A method is disclosed for producing integrated circuit apparatus in which electroconductive interconnection films are disposed adjacent to each other and have an insulating film sandwiched therebetween. The electroconductive films are electrically connected with each other via a through-hole formed in the insulating film. First, a through-hole is formed in an insulating film so as to extend to the surface of a first electroconductive interconnection film. Then, extraneous materials existing on the surfaces of the insulating film and the electroconductive film exposed in the through-hole are removed by a sputter etching method. Next, an insulating film covering film ("covering film") is formed by a sputtering method on said insulating film by using a material which is the same material that is used for forming a second electroconductive interconnection film. Subsequently, the sputter etching method is used again to remove the covering film. Finally, the second electroconductive interconnection film is formed on the insulating film and makes electrical contact with the first electroconductive film via the through-hole.

1. Field of the Invention
This invention relates to a method of producing integrated circuit apparatus and more particularly, to a method of producing integrated circuit apparatus in which electroconductive interconnection films adjacently disposed having an insulating film sandwiched therebetween are electrically connected with each other via a through-hole formed in the insulating film.
2. Description of the Prior Art
Recently, semiconductor large scale integrated circuits (LSI) are formed in a multilevel interconnection structure in many cases in order to meet the requirements of high density and high speed. The multilevel interconnection structure is formed as follows; First, a first electroconductive interconnection film is formed on a substrate to be patterned, and an interlayer insulating film is formed on the first electroconductive interconnection film thus patterned. Next, after an opening through which an electrical connection is taken therebetween has been formed in the interlayer insulating film, a second electroconductive interconnection film is formed on the interlayer insulating film to be patterned. Also, in the same manner as above, an interlayer insulating film is formed on the second electroconductive film thus patterned, then, an opening is formed in the interlayer insulating film, and a third electroconductive interconnection film is further formed on the interlayer insulating film. As shown above, the multilevel interconnection structure is formed such that an insulating film and an electroconductive interconnection film are laminated alternately on a substrate. The opening formed in the insulating film is called "through-hole", through which the electrical connection is taken between upper and lower electroconductive films.
As the electroconductive interconnection film, a metal film made of aluminum or its alloy has been widely used. On the other hand, as the interlayer insulating film, a silicon oxide film and silicon nitride film have been used in many cases. However, the recent trend is that such an oxygen containing insulating film that is formed of silicon oxide, silicon oxide nitride or the like by, for example, the plasma CVD is mainly used for this purpose. This is because the use of oxygen containing insulating film allows to reduce the stress to be applied to an electroconductive interconnection film as compared with the use of silicon nitride film, so that the stress migration of the electroconductive film can be effectively prevented and at the same time, the dielectric capacity can be reduced to improve the signal transmission speed.
With the multilevel interconnection structure, in order to planarize the surface of a film to be formed, it is general to sandwich a silicon compound layer including silica film between insulating films, or to use a silicon compound such as silicon polyimide incombination therewith. These silicon compounds contain oxygen, so that similar to the case of using silicon oxide or silicon oxide nitride as shown above, the stress-migration of an electroconductive interconnection film can be effectively prevented.
In case of producing a semiconductor integrated circuit apparatus in the above-described multilevel interconnection structure, after perforating a through-hole in an interlayer insulating film formed on a first electroconductive interconnection film, a second electroconductive interconnection film is formed on the interlayer insulating film through the steps or the following processes in order to provide a good ohmic contact between the adjacent electroconductive films;
First, the through-hole is perforated in the interlayer insulating film by an etching method with a photo-resist as the mask, and then, the photo-resist is subjected to a dry/wet treatment to be separated and removed therefrom (through-hole forming process). Next, sputter etching is applied thereto under the vacuum condition thereby removing extraneous materials existing on the surfaces of the interlayer insulating film and the electroconductive interconnection film exposed into the through-hole (extraneous materials removing process). In this case, as an extraneous material to be removed therefrom, there can be pointed out, for example, a metal oxide which is produced by reacting a component of the electroconductive interconnection layer with the oxygen in the air to be adhered onto the surface of the electroconductive film exposed into the through-hole, and a reaction product which is produced in the through-hole forming process to be adhered onto the surface of the electroconductive film and the side surface of the insulating film in the through-hole and residually existed even after the photo-resist removing process.
Subsequently, the second electroconductive interconnection film is formed on the interlayer insulating film thus obtained as above by a sputtering method under the same vacuum condition as applied in the extraneous materials removing process (electroconductive interconnection film forming process). As shown above, the sputter etching process for removing these extraneous materials and the sputtering process for forming the second electroconductive interconnection film are carried out subsequently under the same vacuum condition.
In case of an existing silicon compound layer between insulating films, or in case of a silicon compound layer in combination with the other insulating film(s) and insulating films, by heating the substrate under the same vacuum condition as applied in the electroconductive film forming process, gases including moisture are to be sufficiently removed from the silicon compound layer in advance.
In this case, however, according to the experiments, with the conventional method as shown above, it is found that even if the etching conditions in the through-hole forming process and the sputter etching conditions in the extraneous materials removing process are optimized, the ohmic contact between electroconductive interconnection films becomes disadvantageously unstable, and it cannot be taken at all depending on, for example, the temperature hysteresis occurring thereafter. Why such a problem as shown above is arisen was examined variously and found to occur for the following reasons;
First, when the sputter etching technique is applied thereto in the extraneous materials removing process, molecules of the interlayer insulating film are dissociated from its top surface and/or side surface to be adhered onto the surface of the electroconductive film exposed into the through-hole. In the case of being used an oxygen containing insulating film such as to be made of silicon oxide or silicon oxide nitride, the oxygen dissociated from the insulating film is re-combined with a metal component of the electroconductive film exposed into the through-hole thereby to generate a metal oxide to be adhered onto the surface of the electroconductive film itself. As a result, the extraneous materials thus adhered thereonto hamper the complete interface connection of the adjacent electroconductive films, resulting in unstable ohmic contact between the adjacent interconnection layers.
In addition, if a temperature change is additionally applied thereto while the complete interface connection between the electroconductive films cannot be provided, or if an electric current is applied thereto, the stress-migration and/or electro-migration will be generated at the interface thereof, so that the both of electroconductive films can be completely shielded finally. This means that the ohmic contact cannot be obtained at all between the electroconductive films.
This invention was made in consideration of the above-mentioned disadvantageous situation, and an object of this invention is to provide a method of producing integrated circuit apparatus capable of providing a stable and superior ohmic contact between adjacent electroconductive interconnection films and a good resistance to the stress-migration and electro-migration of the electroconductive interconnection films.

Method of forming multilevel interconnections in a semiconductor integrated circuit


An optical module includes a waveguide substrate including an optical waveguide and electrodes that apply electronic signals to the optical waveguide; a relay substrate disposed adjacent to the waveguide substrate; a terminal substrate disposed adjacent to the waveguide substrate and opposite to the relay substrate across the waveguide substrate; and a carrier substrate on which the waveguide substrate, the relay substrate, and the terminal substrate are mounted. The electrodes have a first interconnect unit from the relay substrate to the terminal substrate via the waveguide substrate and second interconnect units from the first interconnect unit and branching on the terminal substrate. Among the second interconnect units, a first interconnect branch includes a capacitor and a terminal resistor; and a second interconnect branch is connected to an interconnect of the carrier substrate via a bias resistor, passes under the waveguide substrate to a DC electrode for bias-adjusting on the relay substrate.

An optical waveguide device using, for example, an electrooptical crystal substrate, such as an LiNbO3 (LN) substrate and LiTaO2 substrate, or a semiconductor substrate, such as GaAs substrate and InP substrate, is known as an optical module. This optical waveguide device is created by forming a metal film made of titanium (Ti) on part of the substrate and causing the film to thermally diffuse, or by executing proton exchange in a benzoic acid after patterning treatment. An electrode is then formed near the optical waveguide to construct the optical module, such as optical modulator.
When such an optical modulator is driven at high speed, the terminal of a signal electrode is assumed to be connected to the terminal of a ground electrode via resistance, thereby forming a traveling wave electrode, and a high-speed microwave signal (electronic signal) is applied from the input side to an RF terminal. At this time, an electric field shifts the refraction factors of a pair of parallel waveguides A and B by +Δ and −Δ, respectively, which consequently shifts the phase difference between the parallel waveguides A and B. In this manner, the signal passing through a Mach-Zehnder interferometer is output from an outgoing waveguide, as intensity-modulated signal light.
By matching the speed of light and the speed of the high-speed microwave signal (electronic signal), high-speed optical response characteristics can be achieved. After traveling through the optical modulator, the electronic signal travels through a capacitor and is terminated at a terminal resistor. Before the capacitor, the electrode is branched into one portion that extends through a bias resistor to be connected to a DC terminal and the other portion that is terminated at a terminal resistor. The optical modulator with this configuration functions as a bias. By applying a voltage to the DC terminal, a bias point and a drive voltage of the Mach-Zehnder unit can be controlled.
Such an optical modulator includes a Mach-Zehnder modulator unit and a relay substrate to which an electronic signal for driving the Mach-Zehnder modulator unit is input. As a technique related to the relay substrate, for example, a technique is known according to which the Mach-Zehnder modulator unit is disposed between a signal input substrate and a signal terminating substrate having a terminal resistor, etc. (see, e.g., Japanese Laid-Open Patent Publication Nos. 2007-139987 and 2003-015096). Another technique is also known according to which a signal input substrate and a signal terminating substrate are disposed on one side of a modulator (see, e.g., Japanese Laid-Open Patent Publication No. 2003-295139). Still another technique is also known according to which a relay substrate is provided as a unit separated from to an optical modulator unit and electrode intervals between RF terminals on the relay substrate are widened (see, e.g., Japanese Laid-Open Patent Publication No. 2010-185979).
In recent years, accompanying advances in techniques for multi-value processing and optical-polarization division multiplexing aimed at large-capacity optical communication, the configuration of the modulator has become more complicated. For example, a modulation method is adopted for the modulator such that two sets of Mach-Zehnder modulator units each having a pair of parallel waveguides are provided and an independent signal is input to the two sets of Mach-Zehnder modulator units to generate multi-value signals multiplexed by optical-polarization division.
According to the configuration that includes the two sets of Mach-Zehnder modulator units, however, the number of signal paths for electronic signals is doubled on a substrate having the Mach-Zehnder modulator units, which brings about a need for space to arrange the signal paths. Accordingly, the number of RF terminals, DC terminals, capacitors, bias resistors, and terminal resistors is also doubled on the relay substrate. This brings about a problem in that the size of the relay substrate, e.g., a length along the parallel waveguides of the Mach-Zehnder modulator units increases and the size of a module accommodating the Mach-Zehnder modulator units increases as well.


A context sensitive undo feature undoes a first change in a document without affecting other changes made by other contexts. A first change is applied within a document. A context of the first change is determined. First data related to the first change is stored in a first stack in response to determining that the first change is associated with a first context. A second change is applied within the document, the second change occurring after the first change. A context of the second change is determined. Second data relating to the second change, associated with a second context, is stored in a second stack. An instruction to undo the first change is received, and an undo function to undo the first change based on the first data is performed without affecting the second change in response to determining that the undo instruction is associated with the first context.

Existing document editing systems may allow for manipulation of more than text. Other contexts that may be edited include, for example, images, tables, and other forms of multi-media. Existing document editing systems allow users to undo edits to a document using an undo command. In existing systems, the undo command may be invoked, for example, through the use of keystrokes (e.g. CTRL+Z) or by selection of an icon (e.g. an undo icon displaying an arrow pointing left). Upon being initiated or selected, the undo command typically causes the most recent change made within the document to be reversed, causing the document to revert to a previous state.

System and method for providing a context sensitive undo function


A combination tool is described that has a housing that includes a first side and an opposed second side, a third side and an opposed fourth side. The sides connect together to define the housing. The housing includes a first end portion and an opposed second end portion that define a longitudinal axis. The combination tool includes a razor mechanism that is connected to the housing. The razor mechanism receives and moves a cutting blade between a first position in the cavity and a second position wherein the cutting blade extends through the housing. The housing defines a channel that includes a floor, a first sidewall and a second sidewall. The first sidewall and the second sidewall have first edges that are connected to the floor and second edges that connect to the first side of the housing. The first sidewall includes a first slot and the second sidewall includes an opposed second slot. The first slot and second slot are positioned in fixed spaced relation from the floor and the second edge. The slots are configured to receive a rasp. The slots are positioned to recess a cutting surface of the rasp in the channel such that at least a portion of the sidewalls extend between the cutting surface and the second edges. A claw is defined in the housing that includes a first tong and a second tong. The claw extracts fasteners from soft materials.

1. Field of the Invention
The present disclosure relates to combination tools used in construction and in particular, to a combination tool that aids in the installation of panels.
2. Description of the Related Art
Combination tools are multi-purpose devices that can be specialized or encompass a broad range of applications. Construction and remodeling often requires the installation of panels or sheeting such as wallboard, cellulose based sheeting, polymers and insulation panels. The installation of paneling requires repetitive tasks such cutting the panel such as a piece of wallboard to the desired dimensions, resurfacing the cut edges for a smooth tight fitting joint, installing and joining the pieces of wallboard together. The resurfacing of the cut edge of the piece of wallboard is required because of the rough surface of the edges after a piece of wallboard is cut and the need for a precision uniform mating surface for any edge in a joint with another piece of wallboard. The skilled tasks of cutting to size and then the resurfacing of the edges remain awkward because of the need to handle multiple tools to perform this task.
Retractable cutting knifes or utility knifes are routinely used to cut or scar the surface of materials such as wallboard for separation into pieces. Utility knifes typically have handles that have an overall ergonomic shape for gripping that includes an approximately rectangular cross-section similar to the handle of a large knife. The elongate length of the handle is aligned with the retractable cutting blade and the relatively narrow width of the housing aids in the handling and alignment of the cutting process.
In contrast, rasps configured for cutting the edges of panels are bulky in that they are separate tools with a flat cutting surfaces that includes an extended handle or are U-shaped with a channel that has a width suitable for the positioning of the edge of the panel. Rasps that have the U-shaped channel configuration for the resurfacing of the edge of a piece of paneling do not require a separate alignment of the rasp with the edge for a precision cut because the channel sides guide the cutting of the rasp. Rasps are also limited in that they typically only cut in a single longitudinal direction. A multifunctional tool is needed that has a housing that is a handle that readily fits into a user's hand for accurate cutting with a retractable blade that can also be rotated to use a rasp positioned in a channel in the housing to resurface the edge of a piece of paneling.
Paneling is routinely fastened onto the structure of a building using threaded fasteners that can be rapidly drilled through the panel and into the supporting structure. It is not uncommon, however, that the fastener is accidentally imbedded into the panel without being connected to a stud or the threads of the fastener no longer engage the panel. The use of a large flat bladed claw hammer commonly found in construction operations to extract the fastener under these circumstances causes excessive damage to the panel. A specialized claw is needed for panels and similar soft material applications that can remove a fastener with a minimal amount of damage to the panel.
A combination tool is needed that is contained in a housing that can be readily manipulated to switch between cutting as a utility knife and resurfacing a rough edge with a rasp positioned in a channel. A further need is for the combination tool to include a claw that can extract a fastener from softer materials.


Provided is a semiconductor device having a high-frequency interconnect, first dummy conductor patterns, an interconnect, and second dummy conductor patterns. The first dummy conductor patterns are arranged in the vicinity of the high-frequency interconnect, and the second dummy conductor patterns are arranged in the vicinity of the interconnect. The minimum value of distance between the high-frequency interconnect and the first dummy conductor patterns is larger than the minimum value of distance between the interconnect and the second dummy conductor patterns.

1. Technical Field
The present invention relates to a semiconductor device.
2. Related Art
FIG. 3 is a plan view showing a conventional semiconductor device. In a semiconductor device 100, dummy conductor patterns 102 are arranged in the vicinity of a high-frequency interconnect 101. The dummy conductor patterns are provided for the purpose of suppressing production of pits, called erosion, which tends to occur in the process of CMP when a pattern of an interconnect layer has dense and scarce portions. More specifically, provision of the dummy conductor patterns 102 facilitates processing of a layer containing the high-frequency interconnect 101 when the semiconductor device 100 is manufactured. The high-frequency interconnect 101 herein functions as an inductor.
Preceding technical literatures relevant to the present invention may be exemplified by Japanese Laid-Open Patent Publication No. 2001-267322, and Ali Hajimiri et al., "Design Issues in CMOS Differential LC Oscillators", IEEE JOURNAL OF SOLID-STATE CIRCUITS, Vol. 34, No. 5, May 1999, pp. 717-724.
A problem, however, arises when high-frequency current flows through the high-frequency interconnect 101 in the semiconductor device 100 shown in FIG. 3. More specifically, eddy current may be produced in the dummy conductor pattern 102 in the vicinity of the high-frequency interconnect as shown in FIG. 4, due to a magnetic field induced around the high-frequency interconnect 101. The drawing is a plan view showing an enlarged view of the portion surrounded by the dashed line in FIG. 3. Arrow A1 in the drawing expresses the direction of current flowing through the high-frequency interconnect 101, and arrows A2 express the direction of eddy current flowing in the dummy conductor pattern 102.
When the eddy current appears in this way, another magnetic field will appear in the direction of canceling the above-described magnetic field, based on Lentz's law. Circuit constants of the high-frequency interconnect 101 may fluctuate, and as a consequence, transmission characteristics of the high-frequency interconnect 101 may fluctuate.

Semiconductor device with a high-frequency interconnect


The disclosed embodiments automate context-compensated rendering of text in a graphical environment. In the disclosed embodiments, the system first receives a specification of the graphical environment that includes text to be rendered in the graphical environment. Next, the system determines the parameters of the local environment near the text (e.g., character size and perturbations for perspective and tilt, pixel density, adjacent (local or background) color and brightness, illumination and shadow effects, etc.). The system then dynamically renders text to compensate for those parameters, in order to display the text more clearly.

1. Field of the Invention
The present invention relates to the display of text in a virtual graphical environment. More specifically, the present invention relates to a method and an apparatus for automated context-compensated rendering of text in a virtual graphical environment. This is particularly useful for text compatible with virtual 3D displays, and with a disparate range of displays.
2. Related Art
Modern computer display technology increasingly provides support for rendering objects in virtual graphical environments, particularly virtual three-dimensional (3D) graphical environments, such as isometric images. These incorporate many more dynamic graphical effects than traditional two-dimensional graphical environments. However, these effects can have a negative impact on the clear display of text. Existing systems that support virtual graphical environments typically render text using static font images with one or more parameters that do not change according to the graphical environment. For example, two-dimensional fonts are typically based on a fixed map and one or more parameters, such as point-size, style, and color. These do not depend on the graphical environment in which the character will be displayed. Therefore the rendered text often may have poor visibility in the graphical environment.
In the prior art, a skillful artist can manually create an illustration, including 3D-like isometric objects, text and lighting effects. A skillful artist may modify the appearance of the text to provide appropriate readability and graphical compatibility with the remainder of the illustration. However, the success of such changes depends upon the skill of the artist. In partly-automated illustrations, such modifications are not automatically provided, and may or may not be achieved by manual human intervention.
During the European Renaissance, talented artists and scientists created "perspective rules" describing how the painting of an object should vary with its apparent location (especially depth) in the graphical environment (such as a landscape). While such rules can be used to display computer-generated images, these rules do not provide for a clear display of text.
In highly-automated illustration techniques, the appearance of text often suffers from poor readability against the graphical context. A common example of this problem is a movie with subtitles. Typically the subtitles are rendered with a fixed graphical style, and these are superimposed on scenes with various graphical properties, such as brightness and color. In some scenes, the subtitles are clearly readable, but in others the subtitles are difficult to read.
Another problem is type-font poor compatibility across disparate displays. Some type-fonts are optimal for low-resolution monochrome (black and white) displays, and others are optimal for high-resolution polychrome (color) displays. A single type-font is typically not optimal across disparate displays, which presents problems for an image on a centralized server computer that is downloaded to disparate client computers and viewed on disparate displays. As a result, customizing an image on a server for a specific client involves notifying the server of client display parameters and the server creating a customized image that is then downloaded and displayed on the client. This approach can significantly increase server load.
Hence, what is needed is a method and an apparatus for rendering text more clearly in a graphical environment, without the limitations of existing systems.

Automated context-compensated rendering of text in a graphical environment


The present invention relates to electrochemical methods for the recovery of ascorbic acid from an ascorbate salt without the co-generation of a waste salt stream and while maintaining high conductivity of the electrochemical cell thereby providing for quantitative conversion of the salts to ascorbic in both batch and continuous mode processes. In one embodiment the feed stream comprising an ascorbate salt is dissociated under the influence of an electric field and subjected to water splitting electrodialysis. The ascorbate ion combines with a proton and the salt cation combines with a hydroxyl ion to form ascorbic acid and base, respectively. The feed stream further comprises an inorganic salt which maintains high conductivity in the cell, facilitates quantitative conversion of ascorbate salts to ascorbic acid in both batch and continuous mode processes, and promotes precipitation and crystallization of ascorbic acid as a fine powder. Electrochemical cells useful in the methods include arrangements with a combination of at least one cation membrane, and at least one bipolar membrane in combination with at least one cation membrane.

Vitamin C is synthesized in plants and most higher animals from D-glucose. However, humans have a genetic defect that prevents the synthesizing of vitamin C. In this regard, humans must consume the required vitamin C in their diets or by supplementation. Because of the recognized need and demand for vitamin C, several different methods for synthesizing it are currently utilized, including the Reichstein process. The starting material for the Reichstein process is glucose, which is converted in several steps to 2-Keto-L-gulonic acid (KLG). KLG is esterified with methanol and acid to form the KLG methyl ester, which is then treated with sodium methoxide in methanol to give sodium ascorbate. Sodium ascorbate is then acidified with sulfuric or hydrochloric acid to give the ascorbic acid product plus an equimolar quantity of an unwanted waste salt.
To eliminate the need of introducing an acid into the ascorbate salt solution which forms a waste salt stream, U.S. Pat. No. 5,702,579 discloses a method of protonating ascorbate salts via electrodialysis using bipolar membranes and monopolar membranes. In this patent publication, the feed stream introduced into the electrochemical cell is limited to an ascorbate salt solution. By limiting the feed stream to just an ascorbate salt solution the conductivity of the electrochemical cell constantly decreases. As such, cell voltage during constant current operation will constantly increase to compensate for the decreased conductivity thereby increasing the overall cost of converting the ascorbate salt to ascorbic acid. Also, continuous conversion of ascorbate salts to ascorbic acid is not efficiently achieved because the presence of increased amounts of ascorbate salts in solution increases the solubility of ascorbic acid thereby rendering it less likely to precipitate out of solution and form fine powder crystals on a continuous basis.
Accordingly, simple electrochemical methods are needed which convert ascorbate salt to ascorbic acid without producing a stream of waste salt, which offer improved conductivity of the feed solution thereby reducing high voltage requirements, and which offer the ability to operate at quantitative conversion of ascorbate salt to ascorbic acid in both batch and continuous mode.

Electrochemical methods for recovery of ascorbic acid


A method for measuring a flow of a fluid in a tube includes heating the fluid in the tube with a heating element. A first signal is measured with a first temperature sensing element at a first location. A second signal is measured with a second temperature sensing element at a second location. At least one temperature signal is calculated based on the first signal and the second signal. The at least one temperature signal includes a difference temperature signal and a sum temperature signal. The difference temperature signal is calculated based on a difference between the second signal and the first signal. The sum temperature signal is calculated based on a sum of the second signal and the first signal. The flow is derived based on the difference temperature signal, the sum temperature signal, or a combination thereof.

What is applied in HPLC are pumps that generate a solvent flow with a defined flow rate (generally referred to as a flow in the following). In so-called isocratic applications, the solvent composition is constant. In contrast to that, in solvent gradients (referred to in short as gradients in the following) two or more solvents are combined with a settable mixing ratio, wherein the mixing ratio is varied in a defined, predetermined manner depending on the time. The use of gradients has great advantages with respect to chromatography and is therefore very widely used in HPLC, in particular in the low flow range.
Generally, in field of liquid chromatography (HPLC=high performance liquid chromatography), the low flow range relates to a flow range with flow rates between just a few nL/min (nanoliters per minute) up to approximately 100 μL/min (microliters per minute). Commonly, a distinction is made here between the nano HPLC with flow rates between approximately 10 nL/min (nanoliters per minute) and approximately 2 μL/min, the capillary HPLC with flow rates between approximately 1 μl/min and approximately 10 μL/min, and the micro HPLC with flow rates between approximately 5 μL/min and 100 μL/min.
In most applications, the total flow of the mixed solvent is constant, but it can also be varied for special purposes in a defined, predetermined manner depending on the time.
For reasons of simplification, so-called binary gradients, i.e. mixtures of 2 solvents, are regarded in the following explanation. The observations also apply in an analogous manner to gradients having more than 2 solvents.
In HPLC, the requirements with respect to the precision of the generated flow rates and to the mixing ratios are very high. Even more important than absolute precision is reproducibility. Here, deviations in the per mil range can already result in inacceptable changes in retention time.
According to the state of the art, the gradients for HPLC are generated either by low-pressure gradient pumps (low pressure gradient=LPG) or by high-pressure gradient pumps (high pressure gradient=HPG). Among other things, HPG pumps have the advantage that the combination of the different solvent flows occurs only at the outlet of the pump, so that changes in mixing ratios take effect immediately. This may be particularly advantageous for the low flow range. In LPG pumps, the mixing occurs at the pump inlet. LPG pumps will not be regarded in any more detail in the below consideration.
When gradients are generated according to the HPG principle, each solvent is conveyed through a dedicated pump block that provides the desired partial flow. The partial flows are combined inside a mixer at the high-pressure side, i.e. near the outlet of the pump, thus resulting in the total flow. The mixing ratio is set by controlling the pump blocks in a suitable manner.
The following observations refer to binary pumps that work with two solvents. This is the simplest case that is most frequently used in the low flow range. Pumps with more than two solvents can be realized in the exact same manner, only that in that case almost all components, such as pump blocks and flow sensors, need to be correspondingly provided more than twice.
A binary HPG pump consists of two pump blocks, wherein the first block conveys a first solvent and the second block conveys a second solvent, with these two partial flows being combined and mixed at the pump outlet. The generation of solvent gradients with a binary HPG pump is explained based on the example of a linear gradient of 0 to 100%. Here, the total flow at the pump outlet is to be constant, and the concentration of the second solvent is to be gradually increased from 0% to 100%.
For this purpose, initially only the first block conveys the first solvent, while the second block stands still. Then, the conveying speed of the first block is continuously decreased while the conveying speed of the second block is increased to the same extent, until finally the first block stands still and the second block provides the entire flow. The sum of the two partial flows, and thus the total flow, is constant in such a gradient.
There are some general problems and challenges in the prior art, particularly occurring in low flow conditions.
In the so-called analytical HPLC, the required flow rates lie in the order of magnitude of just few milliliters per minute. According to the state of the art, such flows are generated by piston pumps based on the displacement principle. Here, the movements of the piston are controlled in such a manner that the required volume per time is displaced, thus resulting in the desired flow. Usually it is not necessary to measure or control the generated flows.
In the low flow range, there is the problem that the movements of the piston cannot always be controlled in such a precise manner that exactly the desired flows are displaced. In addition to that, a relevant part of the displaced flow can be lost due to unavoidable leaks, for example of the pump seals or the valves. Further, the amount of the liquid that is present inside the pump can vary, for example as a result of changes in temperature and pressure that affect the density of the liquid. The flow that is provided at the exit of the pump is accordingly increased or decreased in the course of such volume variations. In the low flow range, in particular in the range of nano HPLC, the flow errors that are caused as a result of this lie in the same order of magnitude as the desired flows themselves and must therefore be compensated for.
The flow may be controlled with the help of flow sensors.
In low flow pumps according to the state of the art, the flows of the individual pump blocks are therefore measured by means of respective sensors. In the event that the flows differ from the desired values, the conveying speeds of the pump blocks are adjusted by corresponding control circuits so as to compensate for the errors.
In this manner, the above-mentioned disturbing effects can be compensated for. In this case, the precision and reproducibility of the flow generation is determined mainly by the precision or reproducibility of the sensors. The characteristics of the pump blocks only play a subordinate role, as they can be largely compensated for by means of the control.
Thus, what is desirable for low flow pumps are sensors that can measure the flows of the pump blocks with a high precision and above all with a high level of reproducibility.
What is usually used for the measurement of the flows in nano HPLC and capillary HPLC are thermal flow sensors or flow sensors according to the shunt principle. There are numerous publications for realizing such controlled pumps, in particular for the low flow range.
U.S. Pat. No. 7,674,375 by Waters Company (see FIG. 1) describes a solution in which a controller 120 controls the two pumps 102 and 104 which generate the two partial flows. They pass the two fluidic resistance elements 108 and 114 and are combined at the outlet by the mixer 110. The pressure drop at each resistance element is proportional to the corresponding flow, and thus represents a measure for the actual partial flow. In total 3 pressure sensors 106, 112 and 116 are provided for measuring the pressure drops, so that the controller 120 can determine the pressure drop at the upper capillary as the difference between the signals of the pressure sensors 106 and 116, and analogously can determine the pressure drop at the lower capillary as the difference between the signals of the pressure sensors 112 and 116.
The partial flows are obtained by dividing the pressure drop by the (previously determined) flow resistance of the respective resistance element.
Exactly the same measuring principle is also described in U.S. Pat. No. 7,927,477 B2 by AB Sciex LLC Company, as well as further members of this patent family.
The measurement by means of dedicated flow sensors is already known from U.S. Pat. No. 3,917,531 by Spectra Physics Company (see FIG. 2). Here, a flow transducer 23 or 23′ that measures the actual flow is used in every flow path.
The signals of the sensors that are referred to as "flow transducers" are transferred to the control devices 26 and 26′ that control the motors 16 and 16′ in such a manner that the flows correspond to the desired values.
This solution is also claimed by various substantially later patents, such as for example U.S. Pat. No. 8,679,333 B2.
Thermal flow sensors according to the state of the art, which can measure the flows that are of interest in the low flow range, are commercially available, for example from Bronkhorst BV Company, Netherlands, or Sensirion AG Company, Switzerland.
However, such prior art flow sensors have certain problems and limitations.
Since flow measurement and flow control by means of flow sensors may also be of interest for the present invention, some aspects of this technology will be regarded in more detail in the following.
There are certain requirements for the flow sensors, which requirements may depend on the field the flow sensors are used in.
HPLC pumps are supposed to cover a flow and pressure range that is as large as possible, so that they may be used versatilely for a wide range of different HPLC columns. For low flow pumps, this requirement also applies to the used flow sensors.
Here, it is advantageous for HPLC that the precision and above all the reproducibility of all processes is to be as high as possible. Thus, the total flow as well as the mixing ratio are advantageously maintained so as to be extremely reproducible.
As has already been explained, in HPLC pumps for the low flow range according to the state of the art, each partial flow is measured by a flow sensor, and the corresponding pump block is controlled by a control circuit in such a manner that the measured flow corresponds to the desired value as precisely as possible. In the event that measuring errors occur in the flow sensors, the actually provided partial flows are correspondingly controlled in a faulty manner. In this case, the total flow as well as the mixing ratio may be flawed.
As has already been mentioned, gradients are often run in HPLC, i.e. the mixing ratio of the solvents is varied in the range between 0 and 100% during each measurement cycle depending on the time. At 0 or 100%, one of the partial flows becomes zero. If in that case the respective pump block was simply stopped, changes in pressure and temperature as well as possible leaks would result in undesired flows, wherein also a negative partial flow, i.e. in the direction of the pump block, could occur. In order to avoid this, each partial flow must always be actively controlled.
If a partial flow is zero, a percentage accuracy specification is not possible for the flow sensor. In this case, what may be looked at instead is the worst case zero signal that is provided by the sensor at actual flow=zero. The zero signal comprises an offset error (mean value) and noise. These values yield the lowest measurable flow, which is just enough to be reliably differentiated from the zero signal.
In the following, the ratio between this lowest and the highest measurable or usable flow is referred to as the dynamic range of the sensor.
The flow rate range in which the HPLC pump with flow sensors can be operated in an expedient manner is determined by the dynamic range of the flow sensors. As a rule of thumb for a sufficient precision and reproducibility, the total flow of the pump should be higher by at least 2 orders of magnitude than the lowest measurable flow of the sensors. Thus, the operating range of the pump (wherein the range is the quotient of the highest and smallest flow rate) is lower than the dynamic range of the used flow sensors by the factor 100.
The above considerations apply for all types of flow sensors, be it thermal flow sensors or flow sensors according to the shunt principle or any other kind of flow sensors.
In the following specific limitations of flow measurement and flow control according to the shunt principle are considered.
The flow measurement according to the shunt principle corresponds to the measurement of electric current according to the shunt principle. Here, a known resistance is inserted into the current-carrying conductor, and the voltage drop at the resistance is measured. The current then results as the quotient of the measured voltage and the resistance value.
In analogy to that, the partial flow to be measured is guided through a known fluidic resistance, and the pressure drop at the resistance element is measured. Then, the flow rate of the partial flow results as the quotient of the measured pressure drop and the fluidic resistance.
The overall structure of a binary gradient pump with flow measurement and regulation according to the shunt principle is shown in FIG. 1 (state of the art). The partial flows that are provided by the two pump blocks 102 or 104 pass the fluidic resistance elements 108 or 114 and are subsequently combined by the mixer 110. The two pressure sensors 106 and 112 measure the pressures at the entrances of the resistance elements or at the exits of the pump blocks. In the following, they are referred to as primary pressures. The pressure sensor 116 measures the pressure behind the resistance elements or at the exit of the entire pump. In the following, it is referred to as the system pressure.
The pressure drop at the resistance element 108 is the difference between the signal of the primary pressure sensor 106 and the system pressure sensor 116. For the resistance element 114, the pressure drop can be gathered from the signals of the primary pressure sensor 112 and the system pressure sensor 116. The system controller determines these pressure drops, calculates the measured partial flows based on them, and controls the pump blocks in such a manner that the measured partial flows correspond to the desired values.
Suitable fluidic resistance elements are for example capillaries with a relatively small internal diameter or with a filling made of porous material. The liquid that flows through them creates a pressure drop that depends on the geometry of the resistance element, the viscosity of the liquid, as well as on the flow rate. If the resistance element is designed in a suitable manner, the relation between the pressure drop and the flow is approximately linear. If the characteristics of the resistance elements as well as the viscosities of the liquids are known, the partial flows can be calculated from the pressure drops. At that, the resistance elements have to be designed in such a manner that in the flow range of interest the pressure drops are high enough so that they can be measured with sufficient accuracy. On the other hand, the resistance elements must not generate too much backpressure, since the pump blocks have to provide this additional pressure.
Usual pressure sensors for high pressures, as they are used in HPLC, are constructed in such a manner that they measure the pressure difference to the ambient pressure, or the absolute pressure, if necessary. However, what is of interest for determining the flow is the pressure drop, i.e. the pressure difference between the entrance and the exit of the resistance element. Differential pressure sensors that can measure a relatively small difference between two very high pressures with good precision would be technically extremely challenging and are not readily available at reasonable costs. Thus, for the flow measurement according to the shunt principle, individual conventional pressure sensors are used, and the differences are calculated either electronically or by means of software, as shown in FIG. 1.
As has already been explained, extremely high requirements have to be met in HPLC concerning the precision and in particular the reproducibility of the partial flows. For this reason, the pressure drops must be measured in an extremely precise and reproducible manner. Good and readily available pressure sensors reach precisions in the order of magnitude of 0.1% of the maximum pressure. However, what is important in the flow measurement according to the shunt principle is the (comparatively low) pressure difference that is created at the resistance element. In this way, inaccuracies of the pressure sensors correspondingly have a stronger effect percentagewise. This will be explained based on an example.
Assume that the pump blocks can provide primary pressures of up to 1000 bar, and the system is designed for a nominal flow of 500 nL/min and a nominal pressure of 800 bar. Here, the nominal pressure is the maximal system pressure that can be reached at the nominal flow.
The resistance elements are designed in such a manner that a maximum pressure drop of 200 bar occurs in them at nominal conditions. This pressure drop is a measure for the actual flow and is measured with the help of the pressure sensors. At that, the primary pressure and system pressure sensors must be designed for 1000 bar. Thus, with pressure sensors with a precision of 0.1%, measuring errors of up to ±1 bar per sensor have to be expected, which may add up to ±2 bar in the most unfavorable case. Based on a pressure difference of 200 bar, this corresponds to an error of up to ±1%, which leads to a flow error of up to ±1%. This is sufficient for chromatographic purposes, as the reproducibility of measurement is usually better by about 1 to 2 orders of magnitude than the absolute precision, thus lying between 0.01% and 0.1%.
If it is desired is to work with the same system with a lower total flow, for example 100 nL/min instead of 500 nL/min, the pressure difference to be measured is now only 40 bar. Now, the maximal measuring error of ±2 bar already has a resulting flow error of ±5%. If the flow setting is even lower, the error increases further.
Conversely, the same system can also provide flows that are higher than the nominal flow. In this case, the pressure differences correspondingly increase at the resistance elements, for example to 600 bar with 1500 nL/min. Accordingly, in that case the system can only provide a maximal pressure of 400 bar.
Thus, the usable flow range of the system is limited at the lower end by the increasing measuring error, and at the upper end by the available column pressure. Depending on what amount of flow errors and which restrictions regarding the column pressure are considered acceptable, the flow measurement of such a system has a dynamic range in the order of magnitude of 1:1000 to 1:2000. This corresponds to a pump operating range from 1:10 to 1:20.
In the following specific limitations of flow measurement and flow control by thermal flow sensors are considered.
Thermal flow sensors for the low flow range according to the state of the art work with a capillary through which the flow to be measured is guided. The capillary is heated by at least one heating element that is attached outside the capillary in the middle of the measuring zone. Temperature sensors are attached outside at the capillary at both ends of the measuring zone, i.e. in the direction of the capillary axis, symmetrically in front and behind the heating element. If there is no flow flowing through the capillary, a symmetrical temperature profile is formed in the measuring zone, since the heat is dissipated evenly towards both sides, i.e. both temperature sensors have the same temperature. If a flow is guided through the capillary, it causes an additional heat transport in flow direction. In this manner, the temperature sensor that is positioned in front of the heating element is cooled off, and the temperature sensor behind the heating element is heated. The difference between the temperatures (referred to as the differential temperature in the following) is a measure for the flow. The differential temperature is measured and converted into a flow rate with the help of a calibration table. Different embodiments of such thermal flow sensors are known, for example from U.S. Pat. No. 5,936,701 A of Bronkhorst B.V. Company, as well as from EP 1144958 B1 of Sensirion AG Company. The function of such flow sensors will be explained in more detail in the following.
One problem of this thermal measuring principle is that, as the flow increases, not only the temperature profile becomes asymmetrical, but also the heat dissipation through the liquid becomes increasingly relevant. Thus, the differential temperature measured by the temperature sensors rises with increasing flow only in the low flow range. In the case that the flow is higher, the heat output of the heating element is dissipated better and better, so that the temperature of both temperature sensors drops as the flow increases. This effect predominates above a certain flow, so that the difference of the temperatures keeps dropping further. Consequently, the sensor signal increases with the flow rate at a low flow, then goes into saturation, and subsequently drops again if the flow is increased even more. Since thermal flow sensors according to the state of the art analyze the differential temperature, the flow signal that is calculated by the sensor drops as well. This can be avoided within certain limits by taking into account the heat removal when calculating the flow signal. This can for example be effected by changing the reference voltage of the analog to digital converter depending on the average temperature of the two temperature sensors, as described in the patent document U.S. Pat. No. 7,490,511.
Even with this improvement, the dynamic range in which a correct and sufficiently precise flow measurement is possible is limited with thermal flow sensors. What can be reached is a dynamic range of approximately 1:5000, that is, such a thermal flow sensor can measure flows in the range between 1 nL/min to 5000 nL/min, for example.
This is a considerably larger dynamic range than in the flow measurement according to the shunt principle, and it facilitates the manufacture of low flow pumps with an operating range of approximately 1:50, and thus a wider area of application. Another advantage is that the thermal flow sensors cause only a small pressure drop, hence the primary pressures have to be only slightly higher than the system pressure. Depending on the design of the system, it is thus possible to either provide system pressures that are higher as compared to the shunt principle, or one can reach a given system pressure using pump blocks that have a lower pressure rating and are thus cheaper.
However, the flow measurement according to the state of the art has certain disadvantages.
A general disadvantage of the flow measurement according to the state of the art is that the dynamic range is still relatively limited. For this reason, low flow pumps with this technology can only be used in a limited flow range. If the desired flow lies below this range, interfering influences of the sensors, such as noise and drift phenomena, become relevant. This leads to measuring inaccuracies, so that the very high level of reproducibility of the total flow and of the solvent composition, as it is required in chromatography, cannot be reached. In the flow measurement according to the shunt principle, the pressure drop at the fluidic resistance elements that are used for measuring becomes too high at the upper end of the dynamic range, so that the pump can no longer generate a sufficiently high system pressure. When it comes to thermal flow sensors, a correct measurement is only possible up to a certain maximal flow, since the measurement signal goes into saturation.
There have been some attempts to solve these problems.
One attempt makes use of replaceable components.
Since the limited flow range is caused by the design of the flow measurement components, one measure is to accommodate these components inside a replaceable module and to offer different modules that are designed so as to be suitable for different specific flow ranges. If the user wishes to work in another flow range, all they have to do is install the respective module.
As far as the flow measurement according to the shunt principle is concerned, it is even only necessary to replace the (comparatively inexpensive) fluidic resistance elements in order to change the flow range. In this manner, the manufacturer of such a low flow pump can offer multiple replaceable resistance elements, so that the entire flow range of interest can be covered.
As far as the flow measurement with thermal flow sensors is concerned, the sensors themselves have to be exchanged. As the sensors are costly, this is not desirable.
The disadvantage of these simple solutions is that such an exchange of sensitive components by the user involves an increased risk of error. For this purpose, the resistance elements have to be designed in such a manner that an exchange can be performed in a simple and functionally reliable way. This is particularly difficult in the low flow range, since the fluidic connections are especially critical here. For instance, dirt particles can get into the system during the exchange, which may lead to plugging or leaks, for example. Moreover, the exchange is an additional work step for the user, which is desirable to avoid.
Low flow systems with replaceable components that work according to the Shunt principle are available on the market. The system NanoLC 400 by Sciex Company works with replaceable flow modules that contain the resistance elements and are offered for three different flow ranges. In the system RSLCnano, which is offered by the applicant, the resistance elements are also replaceable. In addition to that, in this system it is even possible to replace the entire flow measuring system with a module that works with thermal flow sensors instead of the shunt principle.
A further attempt to overcome the disadvantages employs switchable components.
In order to avoid the problems that are associated with the exchange of components, a manual or automatic switching of the flow ranges is also conceivable. For this purpose, multiple flow measuring systems would have to be present in parallel, the exits of which may be switched either by means of establishing respective capillary connections or by high-pressure switch valves.
However, this would result in a high effort and space requirements for the components.
Another solution relates to a flow sensor with an expandable linear measuring range.
WO 2011/075571 A1 proposes a flow sensor that has an expanded dynamic range (see FIG. 3). The measurement is carried out based on the same principle as in the thermal flow sensors that have already been described above. The capillary (404), through which the flow to be measured flows, is heated by a central heating element (406). Two temperature sensors (402a and 402b) are attached at the capillary in a symmetrical manner with respect to the heating element, determining the temperatures in front and behind the heating element. The difference between these temperatures represents a measure for the flow.
A further temperature sensor (402c) is arranged at the heating element, directly detecting the temperature of the heating element. The temperature of the heating element is controlled to the appropriate value (heater setpoint) via a closed control loop.
In this manner, it is avoided that the temperature of the heating element drops at a high flow. Thus, even at higher flow rates, the differential temperature between the two temperature sensors 402a and 402b keeps rising as the flow rate increases. Such a flow sensor can still provide precise measurements of low as well as relatively high flow rates, and thus has a considerably higher dynamic range than conventional thermal flow sensors. However, in the event of even higher flow rates, the thermal resistance between the heating element and the liquid becomes relevant. In that case, even though the temperature of the heating element remains constant, the temperature of the liquid drops with increasing flow. Within certain limits, this can be counteracted through a higher temperature of the heating element, or/and this effect can be taken into account when converting the differential temperature into the flow.
A more severe problem of this solution is that the controlled heating power, and consequently also the temperature difference to be measured, is the smaller the higher the temperature of the inflowing liquid becomes. This is easy to understand by looking at the extreme case that the temperature of the liquid is equal to the target temperature of the heater, or that it exceeds the same. In that case, the heat output becomes zero, i.e. the measured differential temperature also remains zero independently of the flow rate, so that obviously no flow measurement is possible.
As long as the temperature of the inflowing liquid remains below the target temperature of the heating element, the effect can be compensated including the required heating power in the calculation, for example by multiplying the differential temperature by the inverse of the heating power.
However, this entails the disadvantage that the control loop for the heating power reacts relatively slowly. If there are changes of the flow, it takes some time until the controller is settled and the sensor indicates the flow rate correctly again. Thus, such a sensor detects flow changes only with a certain delay.
If such a slow flow sensor is used in an HPLC pump to control the flow, the flow-control loop must be designed to be very slow as well to avoid instabilities. Such an slow control circuit fails to remove flow deviations fast enough, thus the performance of the entire pump remains suboptimal.
Disregarding these problems, a dynamic range of up to approximately 1:10000 can be achieved with such an improved flow sensor according to the state of the art, corresponding to an operating range of the pump of 1:100. This is considerably better than with conventional thermal flow sensors, but still does not cover the entire low flow range.
In light of the above, it is an object to overcome or at least alleviate the shortcomings and disadvantages of the prior art. More particularly, it is an object of the present invention to provide a technology allowing a measurement of a flow of a fluid over a wide range of fluid flows. The technology should yield accurate and reproducible results, and should be simple and easy to use. According to some embodiments, its accuracy and reproducibility should be sufficient for HPLC usage.


Representative implementations of devices and techniques provide gain calibration for analog to digital conversion of time-discrete analog inputs. An adjustable capacitance arrangement is used to reduce or eliminate gain error caused by capacitor mismatch within the ADC. For example, the capacitance arrangement may include an array of multiple switched capacitances arranged to track gain error during search algorithm operation.

Analog-to-digital converters (ADCs) convert time-discrete analog input values to a digital form. A type of ADC, the successive approximation register (SAR) ADC, digitizes the analog input values using a successive approximation search algorithm. While the internal circuitry of the SAR ADC may run at a higher frequency (such as several megahertz (MHz), for example), the sample rate of the SAR ADC is generally a fraction of that frequency (such as several kilohertz (kHz), for example) due to the successive approximation search algorithm used. For example, normally each bit of the SAR ADC is fully realized prior to proceeding on to the next bit.
In general, many of today's microcontroller products can have several SAR ADCs on a single chip. In some high-end products, up to 20 or more ADC instances may be placed on the chip. To reduce the amount of ADC instances, a passive sample and hold (SH) ADC structure can be used with a time multiplexed operating scheme.
In some cases, an external voltage reference may be provided to the ADC. This external reference can be a direct supply to the ADC and also a supply to the sensors of the application, for instance. In such an application, the output of the sensors can be a ratiometric voltage based on the supply, which is converted by the ADC to a digital form for use by the microcontroller. The absolute value of the reference/supply voltage is generally cancelled in this scheme, making the external ADC reference desirable. In another implementation, the voltage reference may be provided by the ADC.
However, gain error can occur within passive SH ADCs, due to the use of two different capacitors: one for analog input sampling and one for the conversion process (internal digital-to-analog conversion). The gain error is associated with a mismatch of these two capacitors. In some cases, an on-chip reference voltage can provide at least a partial remedy for the gain error. Generally though, an on chip reference uses a reference buffer for the switched capacitor load of the ADC. This buffer uses chip area and current, and can produce noise. Further, the use of an on-chip reference disallows many of the benefits of an external reference, including those mentioned above.

Gain calibration for ADC with external reference


An unbalanced magnetron rotatable about the back of a sputtering target and including a nested magnetron part having an outer magnetic pole of a first magnetic polarity surrounding an inner magnetic pole of an opposed second magnetic polarity and an auxiliary magnet increasing the unbalance and adjusting the uniformity of sputtering. In a first embodiment, the auxiliary magnet is horizontally magnetized and placed between the inner pole and the portion of the outer pole near the target periphery. This embodiment most strongly affects the sputtering erosion pattern near the target periphery. In a second embodiment, the auxiliary magnet is vertically magnetized and placed on an opposite side of the rotation axis from the major portion of the nested magnetron part. This embodiment most strongly affects the vertical magnetic field distribution near the wafer and can produce a more uniform magnetic field at the wafer. The two embodiments can be combined.

1. Field of the Invention
The invention relates generally to sputtering of materials. In particular, the invention relates to a magnetron creating a magnetic field to enhance sputtering.
2. Background Art
Sputtering, alternatively called physical vapor deposition (PVD), is the most prevalent method of depositing layers of metals and related materials in the fabrication of semiconductor integrated circuits. The semiconductor industry typically uses DC magnetron sputtering in which a wafer to be sputter deposited is placed in opposition to a metal target across a plasma reactor chamber filled with an argon working gas. The target is biased sufficiently negatively with respect to the chamber that the argon is excited into a plasma. The positively charged argon ions are strongly accelerated toward the negatively biased target and sputter metal atoms from it. The metal atoms dislodged from the target fall at least in part on the wafer and are deposited in a layer thereon.
In metal sputtering, the target or at least its inner surface has substantially the same metallic composition as that desired for the sputter deposited layer, for example, aluminum, copper, titanium, tantalum, tungsten, etc. In reactive sputtering, a chemically reactive gas such as nitrogen is additionally supplied into the chamber and the reactive gas reacts with sputtered metal atoms at the wafer surface to deposit a metal compound on the wafer, such as the refractory metal nitrides TiN, TaN, WN. The refractory nitrides are particularly useful as barrier layers between a dielectric and a later sputtered metal layer, and a layer of the associated refractory metal is sputtered first onto the dielectric to serve as a glue layer promoting adhesion of the metal to the dielectric. Accordingly, it is often advantageous to use the same sputter reactor to deposit a bilayer liner of, for example, Ti/TiN, Ta/TaN, or W/WN. Sputtering is also used to coat the sides of a via hole with a thin copper seed layer that nucleates and provides an electrode for subsequent filling of copper into the hole by electrochemical plating (ECP).
However, for advanced integrated circuits, sputtering suffers from the problem that sputter deposition, as described above, involves a fundamentally ballistic process of transporting sputtered atoms from the target to the wafer. In the process, the sputtered atoms are emitted in a broad pattern about the normal to the target. Such a distribution is ill suited to filling narrow holes, such as via holes extending through an inter-level dielectric layer separating two layers of metallization. Such via holes in advanced devices may have aspect ratios of 3:1 and greater. A broad sputtering pattern causes the top of the high aspect-ratio hole to close before the bottom is filled. As a result, voids form in the sputtered via metallization. Similarly, the sputtered liner layers tend to be much thicker at the top of the via hole than at the bottom.
One method of adapting sputtering to deep hole filling, as well as to other applications, is self-ionized plasma (SIP) sputtering, as disclosed by Fu in U.S. Pat. No. 6,183,614, by Chiang et al. in U.S. patent application, 09/414,614, filed Oct. 8, 1999now U.S. Pat. No. 6,398,929, and by Fu et al. in U.S. patent application, Ser. No. 09/546,798, filed Apr. 11, 2000 and now issued as U.S. Pat. No. 6,306,265, all three incorporated herein by reference in their entireties. SIP sputtering allows a significant fraction of the sputtered atoms to be ionized using a somewhat conventional sputtering reactor. The charged sputtered metal ions can be electrically attracted into narrow via holes in the wafer. Furthermore, the sputtered metal ions can in part be attracted back to the target to further sputter the target, thereby allowing the pressure of the argon working gas to be significantly decreased. In the case of copper, it is possible to eliminate the need for the argon working gas after the plasma has been ignited in a process called sustained self-sputtering (SSS).
Most SIP magnetrons include an outer pole of a first magnetic polarity arranged in a closed band surrounding an inner pole of an opposed, second magnetic polarity. Further, the total magnetic flux integrated over the area of the outer pole, also called the total magnetic intensity, is significantly larger than that of the inner pole, preferably by a factor of at least 1.5. The resultant unbalanced magnetron produces a magnetic field component projecting from the outer pole towards the wafer before that component bends back to close on the back of the outer pole. Such a projecting magnetic field has several advantages. It extends the plasma farther away from the target; it guides ionized sputtered particles towards the wafer; and, it reduces plasma electron leakage to the chamber walls.
An SIP magnetron should be relatively small in order to increase the effective plasma power density, which for a fixed target power increases inversely with the area of the magnetron. A prevalent design for a SIP magnetron includes an outer pole having a generally triangular shape with the triangular base of the outer pole positioned near the periphery and the triangular apex located near the central axis of the chamber about which the magnetron is rotated to provide angularly uniform sputtering of the target.
Such a simply shaped magnetron is relatively constrained in the ease of optimizing its design for the various requirements of a magnetron intended for commercial usage, such as sputtering uniformity, high sputtering rate, projection of the magnetic field, and low operating pressure. A further problem is that sputtered material tends to redeposit at the periphery of the target where the magnetic field tends to be less. The redeposited material is not effectively resputtered and has a crystallography different than the original target. As a result, the redeposited material grows in thickness and tends to flake off, thereby producing deleterious particles which significantly reduce chip yield.
One technique for increasing the peripheral magnetic field and hence preventing redeposition from accumulating includes moving the inner pole closer to the outer pole near the target periphery. However, this change pushes the high-density plasma closer to the grounded or floating shield near the target edge. The proximity of the plasma to such an electrically biased shield has been observed to cause problems with the stability of the plasma as the magnetron sweeps the plasma around the target periphery. Arcing to the shields may occur, which also produces particles. The plasma may shrink away from the shields or even collapse in some situations, obviously severely impacting deposition uniformity and yield. SIP sputtering typically relies upon high target powers, usually identified by high target voltage, for example, around xe2x88x92500 to xe2x88x92800 VDC and requiring powers of 30 kW or more. For reasons of economy, the size of the power supply is selected to operate near its limit. With the plasma positioned close to the shields, plasma fluctuations have been observed which temporarily raise the target voltage to xe2x88x921000 VDC, sufficient to bum out the typically used power supplies.
Accordingly, it is desired to provide an unbalanced magnetron having additional design freedom. It is also desired to increase the sputtering rate near the target periphery without bringing the principal magnetic field too close to the periphery. It is further desired to improve the uniformity of sputter deposition.
A further problem arises from the desire to reduce the argon pressure so that the plasma is barely supported and is operating in conditions close to extinguishment. Such a plasma is unstable. Even if it does not extinguish, it may change in intensity and distribution, effects which degrade the desired uniformity of sputter deposition.
An unbalanced magnetron useful for DC sputtering having a nested magnetron and an auxiliary magnet. The magnetron is rotated about a center of the target being sputtered.
In one aspect of the invention, the auxiliary magnet is a horizontally magnetized planar magnet placed between the inner and outer poles on the side of the inner pole closer to the target periphery. The poles of the planar magnet may be chosen to reinforce the pole of the inner and outer magnetic poles closer to the target. Such a planar auxiliary magnet increases the sputtering rate near the outer target periphery.
In another aspect of the invention, the auxiliary magnet is a vertically magnetized magnet placed on an opposite side of the rotation axis from the major portion of the nested magnetron. Preferably, the polarity of the auxiliary magnet corresponds to the polarity of the outer magnetic pole. Such a vertical auxiliary magnet increases the vertical magnetic field adjacent the wafer.
The two aspects may be combined in a single magnetron.
The nested magnetron has an inner pole of one magnetic polarity surrounded by an outer pole of another polarity and including an auxiliary magnet and is preferably an unbalanced magnetron in which the total magnetic flux of the outer pole is significantly greater than that of the inner pole, for example, in a ratio of at least 1.5. The nested magnetron may have a generally triangular outer shape with the axis of rotation near the apex of the triangle and the base of the triangle near the target periphery.
The auxiliary magnet may be used to optimize various portions of the magnetic field distribution. One effect of the auxiliary magnet may be to increase the unbalance of the magnetic field distribution.

Auxiliary in-plane magnet inside a nested unbalanced magnetron


An apparatus comprising a needle probe comprising a sheath, a heating element, a temperature sensor, and electrical insulation that allows thermal conductivity to be measured in extreme environments, such as in high-temperature irradiation testing. The heating element is contained within the sheath and is electrically conductive. In an embodiment, the heating element is a wire capable of being joule heated when an electrical current is applied. The temperature sensor is contained within the sheath, electrically insulated from the heating element and the sheath. The electrical insulation electrically insulates the sheath, heating element and temperature sensor. The electrical insulation fills the sheath having electrical resistance capable of preventing electrical conduction between the sheath, heating element, and temperature sensor. The control system is connected to the heating element and the temperature sensor.

Current techniques for measuring thermophysical properties, particularly thermal conductivity, in high-temperature, in-pile applications are both slow and inaccurate. For instance, thermophysical properties must be known before new fuel compositions and structural materials are deployed in nuclear reactors. Thermal conductivity is one of the most important properties for predicting fuel and material performance, and is highly dependent on physical structure, chemical composition, and state of matter. During irradiation, the physical structure and chemical composition of nuclear fuels and components change as a function of time and position within the reactor.
Measurement of thermal conductivity of nuclear fuels and materials is currently primarily done in "hot cells." In these cells, previously-irradiated samples are removed from their environment for testing. This technique has several disadvantages: it is expensive and time consuming to repeatedly remove and return samples to the in-pile testing environment, the process may disturb the physical properties of the sample, and this method can only provide a snapshot of the sample's physical properties at the end state when the measurement is made.
Currently, a thermocouple approach is the only technique used to detect thermal conductivity in high-temperature reactor applications (i.e. in-pile testing of nuclear fuel). Typically this approach uses thermocouples inserted into the interior and exterior of a sample. This approach assumes several conditions about the sample: uniform composition, uniform density, minimal gap conductance effects, and uniform heat generation. Additionally, this method of testing requires specially designed samples to minimize these factors. Hence, the current approach requires specialized (non-prototypical) samples and is susceptible to high levels of uncertainty due to the assumptions made. Therefore, a need for an accurate way of measuring thermal conductivity without removing samples is needed.
Additionally, in nuclear applications, transmutation of elements can alter the performance of probe materials as well as potentially cause damage to probe components. For example, tungsten and rhenium thermocouples can be decalibrated by transmutation in-pile. Thus, there is a significant need for probes with both temperature and radiation resistance.

Hot wire needle probe for thermal conductivity detection


A support apparatus for a steering column of an automotive vehicle. The support apparatus comprises an upper and lower brackets through which a lower housing of the steering column is installed to a vehicle body. The lower housing is releasable from the vehicle body through first and second releasing mechanisms. The second releasing mechanism includes a part defining a through-hole through which the front end section of the lower housing is projectable forward. An engaging and releasing device is provided such that the lower housing is engageable with the lower bracket and releasable from the lower bracket when a forward load is applied to the steering column through the engaging and releasing device. Additionally, a guide member is disposed forward of the through-hole to slidingly guide the bottom surface of the lower housing forward generally when the lower housing exits the through-hole.

This invention relates to improvements in a support apparatus for a steering column, and more particularly to the support apparatus for preventing the steering wheel side of a steering column from unexpected jumping when the steering column moves forward upon striking of a vehicle occupant at a vehicle collision.
As well known, a variety of support apparatuses for a steering column have been hitherto developed in order to prevent a so-called secondary collision of a vehicle occupant upon vehicle collision accident. One of them is disclosed in Japanese Patent Provisional Publication No. 11-115770. This support apparatus for a steering column is arranged as follows: The support apparatus includes an upper support structure and a lower support structure which are spaced from each other in the axial direction of a steering column in order to releasably fix the steering column at upper and lower two points to a vehicle body. The steering column is provided with a steering wheel which encases therein an airbag. The upper and lower support structures are in such a support condition to the steering column that each of them allows the steering column to release the steering column toward the front side of a vehicle body under an airbag inflation reaction applied to the steering column when a vehicle collision occurs. Thus, an impact absorption on the side of the steering column is cooperated with an impact absorption by the airbag. Accordingly, the above support apparatus is intended to achieve a secure impact absorption with a low cost.
In the above conventional support apparatus, when the airbag is operated or inflated, the steering column can move forward upon release of the engagement of the steering column from the vehicle body through the upper and lower support structures under the airbag inflation reaction applied to the steering column. However, in this event, the front (lower) end side of the steering column can merely move forward from the lower support structure but is restricted in releasing direction. In other words, the front end section of the steering column is not restricted in at least movement in vertical direction after it has released from the lower support structure. Accordingly, when the steering column moves forward upon receiving the airbag inflation reaction, there is the fear that the rear (upper) end section of the steering column unavoidably jumps upward under collision reaction of the vehicle occupant to the airbag. As a result, the airbag itself will jump upward through the steering wheel so that the vehicle occupant becomes out of a suitable striking position to the airbag.


In one example, the method includes operating a process tool that has a plurality of sensors for sensing at least one parameter associated with the operation of the process tool, obtaining data from the sensors and determining at least one maintenance activity for the process tool based upon the data obtained from the sensors. In another example, data from the sensors is provided to a controller that analyzes the data and indicates desired variations in at least one maintenance activity to be performed on the process tool based upon the analysis of the data. In yet another example, the controller identifies a plurality of maintenance activities to be performed on the process tool based upon the analysis of the data.

1. Field of the Invention
This invention relates generally to the field of semiconductor device manufacturing and, more particularly, to a method of dynamically designing a preventative maintenance schedule based upon sensor data, and a system for accomplishing same.
2. Description of the Related Art
There is a constant drive within the semiconductor industry to increase the quality, reliability and throughput of integrated circuit devices, e.g., microprocessors, memory devices, and the like. This drive is fueled by consumer demands for higher quality computers and electronic devices that operate more reliably. These demands have resulted in a continual improvement in the manufacture of semiconductor devices, e.g., transistors, as well as in the manufacture of integrated circuit devices incorporating such transistors. Additionally, reducing the defects in the manufacture of the components of a typical transistor also lowers the overall cost per transistor as well as the cost of integrated circuit devices incorporating such transistors.
Semiconductor devices are manufactured from wafers comprised of a semiconducting material. Layers of materials are added, removed, and/or treated during fabrication to create the electrical circuits that make up the device. The fabrication essentially comprises four basic operations. Although there are only four basic operations, they can be combined in hundreds of different ways, depending upon the particular fabrication process.
Four operations typically used in the manufacture of semiconductor devices are:                layering, or adding thin layers of various materials to a wafer from which a semiconductor device is produced;        patterning, or removing selected portions of added layers;        doping, or placing specific amounts of dopants in the wafer surface through openings in the added layers; and        heat treatment, or heating and cooling the materials to produce desired effects in the processed wafer.
The technologies underlying semiconductor processing tools have attracted increased attention over the last several years, resulting in substantial refinements. However, despite the advances made in this area, many of the processing tools that are currently commercially available suffer certain deficiencies. In particular, such tools often lack advanced process data monitoring capabilities, such as the ability to provide historical parametric data in a user-friendly format, as well as event logging, real-time graphical display of both current processing parameters and the processing parameters of the entire run, and remote, i.e., local site and worldwide, monitoring. These deficiencies can engender nonoptimal control of critical processing parameters, such as throughput, accuracy, stability and repeatability, processing temperatures, mechanical tool parameters, and the like. This variability manifests itself as within-run disparities, run-to-run disparities and tool-to-tool disparities that can propagate into deviations in product quality and performance, whereas an ideal monitoring and diagnostics system for such tools would provide a means of monitoring this variability, as well as providing means for optimizing control of critical parameters.
Most modern integrated circuit device manufacturing facilities make great efforts in attempting to control the various process operations performed in manufacturing integrated circuit devices. Such efforts typically involve the collection of large amounts of data from a variety of sensors employed in the fabrication facility. These sensors may be integrated within the various processing tools, or they may be part of various offline metrology tools. The data for such sensors may be collected on a routine or random basis. At least some of the data obtained by the sensors is typically stored, at least for some period of time, in one or more databases. Some of the data collected may not be stored for any significant duration. For example, collected data that indicates that the monitored process is performing within an acceptable operating range may be discarded after a period of time.
A variety of different types of process tools are employed in the manufacture of integrated circuits. Examples of such tools are deposition tools, etching tools, ion implant tools, chemical mechanical polishing tools, furnaces, rapid thermal anneal chambers, etc. These types of tools perform, in some cases, very complex and important process operations. Moreover, the tools themselves are very complex pieces of equipment that must be properly maintained so that they can continue to produce the desired results during operation. Accordingly, a preventative maintenance program is normally established for the tools. The preventative maintenance program often involves checking a great number of operating aspects of the process tool. Preventative maintenance programs are typically standardized in the sense that all tools of the same type, e.g., a particular manufacturer's deposition tool, will be subjected to the same type of preventative maintenance procedures. In many cases, the tool manufacturer specifies the precise preventative maintenance procedures to be performed on the tool. Such preventative maintenance, while desirable in one respect, can be very time-consuming to complete. While such tools are down for preventative maintenance care, the overall efficiency of the fabrication facility may suffer. What is desirable is a method and system for performing an appropriate degree of preventative maintenance on the process tools without having excessive down-time for the tools during the preventative maintenance program.
The present invention is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above.

Method of dynamically designing a preventative maintenance schedule based upon sensor data, and system for accomplishing same


A fluoroelastomer comprising 74 to 80% by mole of vinylidene fluoride, 4 to 12% by mole of tetrafluoroethylene, 14 to 18% by mole of hexafluoropropene and 0.3 to 1.3% by mole of perfluoro(alkyl vinyl ether), the sum total being 100% by mole, gives vulcanization products having well balanced high levels of low-temperature characteristics and methanol resistance, and suppressed change in the hardness with time after the secondary vulcanization.

1. Field of the Invention
The present invention relates to a fluoroelastomer and its cross-linkable composition and more particularly to a fluoroelastomer capable of producing vulcanization products having distinguished low-temperature characteristics and methanol resistance, and its vulcanizable composition.
2. Related Prior Art
(1) An elastomeric terpolymer comprising 57 to 61% by weight (71.1 to 76.0% by mole) of vinylidene fluoride, 10 to 14% by weight (13.5 to 17.9% by mole) of tetrafluoroethylene and 27 to 31% by weight (8.1 to 11.6% by mole) of hexafluoropropene, the sum total being 100% by weight (or by mole), disclosed in JP-B-62-1965 (U.S. Pat. No. 4,123,603), produces vulcanization products having a low glass transition temperature (Tg), a low compression set at low temperature and low pressure, and also a good methanol resistance, but have no satisfactory level of low-temperature characteristics (TR-10) yet. The elastomeric terpolymer has a low vulcanization speed with a polyol-based cross-linking agent. Thus, injection molding, etc. cannot be effectively used for the elastomeric terpolymer.
(2) A fluoroelastomer comprising 60.5 to 64% by weight (76.6 to 79.4% by mole) of vinylidene fluoride, 5 to 8% by weight (4.0 to 6.5% by mole) of tetrafluoroethylene and 30 to 33% by weight (15.0 to 17.4% by mole) of hexafluoropropene, the sum total being 100% by weight (or by mole), disclosed in JP-A-6-49138 (Italian Patent Application No. 41,003A/90), discloses its vulcanization products having not only the similar low-temperature characteristics to those of the vulcanization products from the elastomeric terpolymer (1), but also a lower TR (temperature contraction) value and a lower degree of crystallization and furthermore a higher vulcanization speed than that of the vulcanization products from the elastomeric terpolymer (1). But, as the vulcanization products from the fluoroelastomer (2) has a poor methanol resistance, its applications are limited. To overcome the poor methanol resistance by adjusting the vulcanizable composition with some additives, i.e. a filler, a mixing ratio of the filler must be increased, resulting in an increase in the hardness of vulcanization products. Its applications are likewise limited.
As to the low-temperature characteristics to be good, TR-70 is still below the satisfactory level. To improve TR-70 within the said composition range of the fluoroelastomer, it would be effective to increase the proportion of hexafluoropropene, but the increase of hexafluoropropene would inevitably deteriorate a TR-10 value of vulcanization products. That is, it is difficult to maintain a good balance between physical properties. As to the hardness of vulcanization products, the hardness tends to unfavorably increase with time in the said composition range of the fluoroelastomer.
(3) A fluoroelastomeric copolymer comprising 48 to 65% by weight (64.7 to 81.4% by mole) of vinylidene fluoride, 0 to 17% by weight (0 to 15% by mole) of tetrafluoroethylene, 21 to 36% by weight (10.8 to 21.9% by mole) of hexafluoropropene and 3 to 9% by weight (1.4 to 4.9% by mole) of perfluoro(alkyl vinyl ether), the sum total being 100% by weight (or by mole), where "% by mole" shows proportions of individual comonomers, when perfluoro(methyl vinyl ether) is used as perfluoro(alkyl vinyl ether), disclosed in JP-A-6-128334, is directed to improvement of the low-temperature characteristics of vulcanization products from the said fluoroelastomer (2), where a portion of hexafluoropropene of the fluoroelastomer (2) is replaced with about 8% by weight (about 4% by mole) of perfluoro(methyl vinyl ether) in the said composition range of the fluoroelastomeric copolymer (2), whereby the TR-10 value of the vulcanization products was inproved by 3.degree. C., as shown in Tables 3 and 4.
However, the fluoroelastomeric copolymer within the above-mentioned composition range has a low vulcanization speed with a polyol-based cross-linking agent. To obtain a practical vulcanization speed, the mixing ratio of a vulcanization promoter must be increased, resulting in an increase in the vulcanization minimum torque. Injection molding thus will be unfavorable.
(4) A fluoroelastomeric copolymer comprising 30 to 47% by weight (45.4 to 67.5% by mole) of vinylidene fluoride, 10 to 30% by weight (8.9 to 29.4% by mole) of tetrafluoroethylene, 18 to 40% by weight (11.2 to 27.9% by mole) of hexafluoropropene and 3 to 20% by weight (1.5 to 11.7% by mole) of perfluoro(alkyl vinyl ether), the sum total being 100% by weight (or by mole), where "% by mole" shows proportions of individual comonomers, when perfluoro(methyl vinyl ether) is used as perfluoro(alkyl vinyl ether), disclosed in JP-A-6-145252, is suitable for the production of shaft seals and fuel hoses in contact with motor oil or gasoline containing an alcohol, particularly methanol, but its vulcanization products have low-temperature characteristics, for example a TR-10 value as low as -13 to -16.5.degree. C. Thus, the service temperature will be limited.
(5) A fluoroelastomer comprising 48 to 65% by weight (66. 1 to 87.0% by mole) of vinylidene fluoride, 4 to 15% by weight (2.2 to 13.3% by mole) of tetrafluoroethylene, 8 to 23% by weight (2.9 to 13.9% by mole) of hexafluoropropene and 17 to 30% by weight (5.6 to 16.1% by mole) of perfluoro(alkyl vinyl ether), the sum total being 100% by weight (or by mole), where "% by mole" shows proportions of individual comonomers, when perfluoro(methyl vinyl ether) is used as perfluoro(alkyl vinyl ether), disclosed in JP-B-53-4035, shows that the vulcanization products have good low-temperature characteristics, but its Examples show the fluoroelastomer has a low vulcanization speed, that is, requirements of 168.degree. C. for 20 minutes (Example 5) or 177.degree. C. for 15 minutes (Example 7) for the primary vulcanization and further requirements of long time for the post-curing. Thus, injection molding will be difficult to conduct.

Fluoroelastomer and its cross-linkable composition


The invention concerns the use of compounds of formula (I), in which R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, m and n have the meanings indicated herein for use in the treatment of sigma-receptor modulated disorders. ##STR1##

British Patent 1313781 describes substituted piperidines which are distinguished by a long-lasting, centrally stimulating action. One of the active compounds coming under the British patent, for which the INN budipine was later recommended, is being tested in the therapy of Parkinsonism. Furthermore, the prior art (e.g. German Patent Specification 10 05 067, German Patent Specification 871 899, German Patent Specification 875 660, East German Patent Specification 50 603 and U.S. Pat. No. 2,411,664) discloses a number of 1-pyrrolidino- and 1-piperidinopropanols and -butanols, such as, for example, biperidin, cycrimine, pridinol, procyclidine, trihexyphenidyl, triperidin or difenidol, which in some cases can likewise be employed in the therapy of Parkinsonism.

Substituted piperidine or pyrrolidine compounds for treating sigma-receptor modulated disorders

Byk Gulden Lomberg Chemische Fabrik GmbH