An improved filling composition for coated confectionery products, particularly chocolate and chocolate-based confectionery products with an unrefrigerated shelf-life of more than about four weeks, when properly stored and handled is provided. Provided is a filling composition with a significant reduction in fat content, particularly in cocoa butter and other saturated fats, and a significant reduction in overall caloric content when compared to conventional chocolate-based, coated confections. This calorie reduction, for example, may be more than about 40% in a confection of the invention with a 1:1 ratio by weight of coating and filling when compared to similar conventional confections.

The invention generally relates to reduced fat, reduced calorie confectionery products, particularly reduced fat, reduced calorie, coated chocolate confections.
Confectionery products typically are formed from high calorie, high fat compositions made from a variety of fats, sugars, starches, flavorings, nuts and other similar ingredients. Such products include confections with high calorie, high fat, flavored filling mixtures coated by chocolates, chocolate-based coatings, sugared, fat containing coatings, or other such coatings that form a shell-like exterior around the high calorie, high fat filling.
In such coated confections, the filling mixtures typically are a major contributor to the organoleptic characteristics, flavor profiles, textures, and mouth feel characteristics of the confections. In many such coated confections, the fillings provide the dominant sweetness and flavor component of the confection. Thus, the organoleptic properties, dissolution rate and texture of the fillings frequently are a critical concern in ensuring that the confection meets the desired requirements for a commercially acceptable product. In addition, the shelf-life of the filling mixtures and their interactions with the shell-like coatings of such confections are a major factor in the storage conditions required for the confections and their expected shelf-life. Accordingly, the composition and properties of the filling mixtures as they affect the shelf-life of the confectionery products also are significant concerns both in the production of the products and in the development of new, improved confectionery products.
In conventional coated confections with chocolate or chocolate-based fillings, the flavor, texture and organoleptic qualities of the fillings normally are dependent on the fat components of the chocolate or chocolate-based components and also on the high calorie sweeteners, typically sucrose, used in such fillings. Cocoa butter generally is the predominant fat component in chocolate or chocolate based fillings. Cocoa butter has a relatively narrow, sharp melting point range that is sufficiently below normal body temperatures so that the chocolate fillings quickly melt in a consumer""s mouth. Cocoa butter""s rapid melting characteristic further allows for the rapid release of desirable volatile flavor components, and provides a viscous, flowable mass that provides desirable organoleptic, texture and mouth feel characteristics. The use of cocoa butter, in addition, allows for the suspension and fine dispersion of water soluble, high calorie sweeteners throughout the filling. Consequently, those sweeteners may be released from the filling quickly and without gritty or other unwanted residues.
Conventional high fat, high calorie chocolate fillings typically contain very low amounts of water, and thus have a low water activity or aw. As referred to herein, the water activity of a confectionery product component or part of a component is a measure of the free water released by the product as a function of the water vapor pressure produced by the product or product component in a closed space. The aw is expressed as a ratio of this vapor pressure over the vapor pressure of liquid water at the same temperature. Water activity is commonly measured by determining the relative humidity of the air space above a product sample at room temperature, under controlled conditions, which then is divided by 100, the assumed relative humidity of liquid water under those conditions. In other words, a product that produced a relative humidity of 45% at room temperature has an aw of 0.45.
One benefit of low water contents in conventional high fat, high calorie fillings is that such fillings, in combination with conventional coating which also have a low aw, provide a relatively long, unrefrigerated shelf-life when transported and stored under proper conditions. The low water contents and water activities of such confections, and particularly the fillings, inhibits the growth of undesirable spoilage and other microorganisms. The low water contents and aw of conventional coated confections also reduce the risk of deleterious effects on texture, appearance, organoleptic and other properties of the confections due to the presence of significant amounts of free water in the confection.
The release of appreciable amounts of free water from a confectionery product, particularly coated confectionery fillings, encourages the growth of undesirable microorganisms by providing a favorable environment for microorganisms in the presence of readily available food sources, e.g., the fats and sweeteners comprising the confection. Furthermore, the presence of free water in a coated confection often leads to the build up of fluids at the interface between the coating and the filling that can weaken or crack the coating, and may lead to partial dissolution of the water soluble components of the filling coating. If sufficient free water is released, then seepage from confection may occur producing an undesirable appearance, and contaminating surrounding products and surfaces.
The release of excess free water from such fillings further may result in water migration from the filling into the coating which can lead to a variety of coating failures, discoloration or dissolution of the coatings, as well as an undesirable alteration of the confection""s appearance and texture. Further, the release of excess water in such products may lead to the hardening and increasing of the chocolate""s melting point and the undesirable appearance of a xe2x80x9cbloomxe2x80x9d or presence of cocoa fats on the exterior surface of confectionery coatings.
The preferred water activity for the fillings used in coated confectionery products is usually less than about 0.8. This is below the water activity generally necessary to release sufficient free water to support significant undesirable microorganism growth and to cause significant undesirable functional changes in the fillings or the coatings used in conventional confections.
Conventional high fat, high calorie, coated chocolate or chocolate-based confections typically contain about 30% to 60% by weight sugar, about 10% to 70% by weight chocolate liquor (which contains about 50% by weight cocoa butter and finely ground cocoa bean), about 20% to 25% by weight added cocoa butter, and small amounts of other ingredients including nuts, fruits and flavoring. Not only do conventional chocolate confections commonly contain 30% to 34% by weight total fat in the form of cocoa butter, they are usually high in saturated fats. In many instances, such high concentrations of saturated fats in a confection is considered undesirable in view of the established adverse health effects of saturated fats in food products. Similarly, the combination of the amounts of fats in conventional chocolate confections and the relatively high sweetener content of such products results in a product with a relatively high caloric content which is undesirable for those on a reduced calorie diet by choice or due to medical necessity.
Consequently, there has been considerable interest in reducing the fat and calorie contents in coated confectionery products. Several of such efforts have focused on attempts to achieve significant fat and calorie reductions while obtaining flavor, texture, organoleptic and mouth feel properties very similar to, if not identical to those of conventional high fat, high calorie confections.
In one approach, the cocoa and other fats used in conventional confections are replaced by fat substitutes and fat mimetics. One effort using that approach was directed to developing reduced calorie chocolates using fat substitutes and mimetics that simulate the texture and organoleptic properties of cocoa butter, such as those described in Surber et al., U.S. Pat. No. 5,474,795 and the references cited therein.
In those efforts, a primary concern was the development of properties and processing procedures for fat substitutes and mimetics to provide them with organoleptic, rheological and thermal properties closely simulating cocoa butter and cocoa butter containing chocolate products. Such efforts included Surber et al.""s use of non-digestible fatty acids that mimicked the rheological and thermal properties of cocoa butter, and blends of such fat mimetics with sweeteners and flavoring agents, polyesters or polyethers. Others, such as Mentink et al., U.S. Pat. No. 5,360,621, used various polyols as sweetener substitutes and bulking agents for the same purposes. In another approach, such as discussed in De Soete et al., Int. Pub. WO 93/02566, undesirable fats and high calorie sweeteners were replaced with sugars with mixtures of inulins, fructo-oligosaccharides, polyols and other high-intensity sweeteners.
An alternative approach for reducing undesirable fats and high calorie sweeteners in chocolate based confectionery products is to substitute water for various amounts of cocoa butters and high calorie sweeteners. For example, Bodor, EPO Pub. No. 0,145,085, discloses a low calorie chocolate product using an edible, oil-in-water emulsion containing from 8%-70% by weight percent of a monosaccharide, an oligosaccharide, a polysaccharide or mixtures thereof, where at least 5% by weight of the mono-, oligo, or polysaccharide was in the form of crystals or solid particles that did not exceed 40 microns in size. In Cain et al., EPO Pub. No. 0,547,658A1, low calorie confectionery fillings are disclosed containing 5%-50% by weight of fat in a fat continuous emulsion with a water phase of 10%-60% by weight. The remaining 90% to 40% by weight of that product is an acidity regulator, thickener, bulking agent emulsifier, sweetener, flavor, colorant, humectant, and/or preservative.
However, the use of significant quantities of water to reduce fat and caloric content of confectionery products frequently causes significant undesirable changes in the chocolate products, particularly in coated, chocolate confectionery products. For example, the addition of water to many chocolate-based fillings increased the hardness and/or brittleness of the product, as well as the product""s melting point, and may adversely affect the organoleptic and color properties of the product. In many products, the use of significant amounts of water to reduce fat or caloric contents produces products with unpleasant taste and organoleptic properties, gritty textures, and cracking and leaking problems. For example, Cain et al. reports several efforts to produce shelf stable coated chocolate products, but reported inconsistent results due to cracking and disruptions in the chocolate coating. Consequently, Cain et al. recommended the use of a second, sealing, coating surrounding its chocolate-based filling to protect against water loss from the filling and the resulting loss of product properties.
Thus, it is desirable to provide an improved, low fat, low calorie filling for coated chocolate-based product by replacing saturated and other fats and high calorie sweeteners with water to the extent possible. Such improved fillings should have a sufficiently low water activity to reduce, and possibly prevent, the release of free water from the filling in amounts that will adversely affect the coating layer, the microbiological stability of the product, and other organoleptic, taste and texture properties. It also is desirable to incorporate in such fillings fat mimetic that provide further calorie reduction opportunities and beneficial organoleptic, texture and other product properties.
The present invention provides an improved filling composition for coated confectionery products, particularly chocolate and chocolate-based confectionery products with an unrefrigerated shelf-life of more than about four weeks, when properly stored and handled. The invention provides a filling composition with a significant reduction in fat content, particularly in cocoa butter and other saturated fats, and a significant reduction in overall caloric content when compared to conventional chocolate-based, coated confections. This calorie reduction, for example, may be more than about 40% in a confection of the invention with a 1:1 ratio by weight of coating and filling when compared to similar conventional confections.
The filling of the invention comprises water, one or more fat mimetics, one or more reduced calorie sucrose substitutes, a flavoring composition mixture and a humectant. In one preferred embodiment, the fat mimetic also acts as an emulsifier for the water insoluble components of the filling and the sucrose substitutes also serve as humectants providing an aw of less than about 0.75. This filling composition typically is coated with a conventional chocolate and chocolate-based composition, as well as other conventional coating compositions.
In particular, the substitution of water for a relatively large proportion of the saturated fats typically found in conventional conversions permits significant fat reductions, and with the use of reduced calorie sucrose substitutes, significant reductions of the calorie content of the confections of the invention. The use of sucrose substitutes such as monosaccharides, sugar alcohols and artificial sweeteners, and polymeric reduced calorie carbohydrates allows for the use of lower calorie sweeteners with varying sweetness intensities. This provides additional flexibility in adjusting the balance of the confection""s caloric content and its desired sweeteners levels. Lower molecular weight sucrose substitutes preferably are used to provide desired sweetness levels and as humectants to modify the water activity of the filling composition to achieve the desired unrefrigerated shelf-life and other previously mentioned advantageous properties.
In one preferred embodiment, the flavoring composition typically includes cocoa liquor mixtures, milk chocolate mixtures, or chocolate-hazelnut mixtures. Other confectionery flavors, such as nuts and nut oils, fruits and fruit oils and artificial fruit flavorings, mint oils and other conventional flavorings used in coated chocolate products also may be incorporated in the filling composition.
The water content of the filling may be supplied from the addition of liquid water during the preparation of the filling composition, as an ingredient of one or more components of the filling mixture such as milk, or from a combination of different sources. The amount of the total water content of the filling mixture will depend on the desired properties of the filling mixture and the expected composition of the final confectionery product. In one preferred embodiment, the water content of the filling composition is between about 15% to about 25% by weight. In this preferred embodiment, the amount of water incorporated in the filling composition permits significant fat and calorie reductions when compared to conventional high fat, high calorie confections, without significant adverse effects on the hardness, texture, mouth feel and organoleptic properties of the filling.
In one preferred embodiment, inulin or an inulin based composition is used as a fat mimetic to provide fat and calorie reduction, as well as improved organoleptic, texture and melting characteristics. The inulin component also is used to emulsify the water, water-based and fat-containing components of the filling. In that preferred embodiment, a sufficient amount of inulin also is used to provide gelling properties that ensure that the filling texture, consistency and viscosity is suitable for use with chocolate and chocolate based coatings. In this embodiment, the inulin component of the mixture is preferably about 20% by weight of the filling and may be up to about 50% by weight, as long as the inulin component provides sufficient texture and body to the filling composition.
In one preferred embodiment, the humectant used in the invention preferably is one or more of a reduced calorie sucrose substitutes, such as xylitol, the sugar alcohols, glycerol, erythritol, sorbitol, lactitol, maltitol, mannitol, isomalt and other low calorie, relatively low molecular weight carbohydrates and sweeteners. The humectants are present in amounts effective to maintain the aw of the filling preferably at less than about 0.75, and most preferably below about 0.7. Such water activities, in combination with the water activities of conventional coatings, provides a coated, confectionery product with an unrefrigerated shelf-life of at least 4 weeks and as long as six to twelve months when stored at typical room temperatures and unrefrigerated temperatures commonly accepted as suitable for storage of chocolate products.
Texture modifiers and builders such as starch maltodextrins, and starch systems such as tapioca, potato, rice and corn starches also may be incorporated in the filling of the invention as may be needed for certain applications. Similarly, various proteins also may be used as texture and mouth feel modifiers, such as egg whites, low bloom gelatins, casein, milk protein isolates and milk (homogenized, ranging from 18% by weight fat to skim milk). The preferred embodiment of the filling of the invention also may include preservatives such as sorbates, and butter or other fats for flavor or texture modification.
The preferred confectionery coatings are conventional chocolate coatings with a water activity, aw, of about 0.2, or a similar chocolate-based coatings. Other non-chocolate coatings with water activities sufficiently low to provide an extended, unrefrigerated shelf-life when applied to the filling of the invention may also be used. Such coatings typically include white chocolates, fruit flavored coatings, and similar coatings with flavor profiles, hardness and molding characteristics suitable for coating chocolate or chocolate-based confectionery fillings.
The invention accordingly provides a reduced fat, reduced calorie confectionery product with a desirable and commercially acceptable texture, mouth feel flavor profile. The product is shelf stable under unrefrigerated conditions for at least about 4 weeks and may provide greater than 40% reduction in calorie content when compared to conventional filled, coated, chocolate confections. This is accomplished using a combination of fat reduction, moisture addition and sucrose substitute strategies to produce confectionery products with organoleptic, texture, taste and other properties comparable with milk chocolates, as well as other chocolate or chocolate-based compositions.
The confection of the invention preferably comprises a flavored filling composition covered or enrobed by a confectionery coating composition. The invention may also be used for molded, filled confectionery products which include products with a chocolate and hazelnut flavored, soft, readily meltable filling within a conventional molded chocolate shell.
The confectionery coating used in the invention typically includes conventional chocolate coatings, white chocolate coatings, fruit flavored coatings or similar conventional coatings or confectionery products. In addition, reduced fat and reduced calorie confectionery coatings may be used, subject to the coating""s compatibility with the filling composition and the aw of the coating as it may affect the shelf-life of the confection. The coatings used in the invention generally are formulated with a relatively low water content and have an aw commonly in the range of about 0.1 to 0.3, and more preferably about 0.2. Confectionery coatings with a greater or lesser water activities also may be used where the water activities of the filling composition and the coating are adjusted to provide a desired unrefrigerated shelf-life of at least four weeks and preferably from six to twelve months.
The filling of the invention preferably is a combination of water, one or more fat mimetics, one or more sweeteners effective as sucrose substitutes, one or more humectants (which may include the sucrose substitutes), texture modifiers (where necessary), and a flavoring composition, typically a chocolate or chocolate-based composition, or a chocolate-hazelnut flavored composition. The filling composition also may include other components such as nut pieces, nut oils, fruit pieces, fruit oils and other flavorings or flavor components. The flavor components further may include emulsions of flavoring oils and water, with suitable emulsifiers.
To provide significant fat and calorie reduction, the cocoa butter and other saturated fats commonly found in conventional fillings are replaced with water in an amount sufficient to provide the desired fat content reduction and calorie reduction, while maintaining acceptable texture properties, organoleptic properties and a desired dissolution rate of the filling components. The amount of water used in a particular filling composition will vary depending on the specific filling and coating ingredients and, in particular, the amount and nature of the fat mimetic and sucrose substitutes used in the filling composition. The preferred water content of the filling is from about 15 to about 25% by weight, and most preferably about 20% by weight of the filling composition and may be varied depending on the particular use of the invention.
In one preferred embodiment, one or more humectant components are present in amounts effective to provide a predetermined water activity level for the filling alone, and in combination with the aw of the coating, sufficient to produce a shelf stable, commercially acceptable chocolate product with an unrefrigerated shelf-life of at least about four weeks, and as long as about six to twelve months or longer. Thus, by the effective choice of one or more humectants which affect the water activity of the fillings and by increasing or decreasing the amount of humectants, the water activity of the filling composition may be adjusted to provide a water activity sufficient to produce a predetermined minimum shelf-life.
The humectant components preferred for this purpose include relatively low molecular weight sugar alcohols including, for example, xylitol, glycerol, erythritol, sorbitol, lactitol (monohydrate, dehydrate or anhydrous), maltitol (crystalline or syrup), mannitol and isomalt. These sugar alcohols also preferably act as reduced calorie substitutes for the sucrose component of conventional confections. Thus, the preferred low molecular weight sucrose substitutes act in a dual role as humectant controlling the aw of the filling and providing significant source of calorie reductions in the filling.
As presently understood, any of the optical isomers and crystalline forms of such sugar alcohols (and other similar components) may be used as an appropriate humectants, and sucrose substitutes. In addition, several of the preferred sugar alcohols are commercially available as syrups which also may be used in the preferred filling. Other low calorie, low molecular weight carbohydrates that are sufficiently soluble in water to provide water activity control also may be used as effective humectants and sucrose substitutes depending on their particular properties and suitability for use in the filling of the invention.
In one preferred embodiment, the humectants used in the filling composition are effective, in combination with the other filling components, to produce an aw of less than about 0.75, and most preferably an aw below 0.7. The relatively low aw of the filling compositions, notwithstanding their relatively high water contents, discourages the growth of undesirable microorganisms, prevents cracking, substantially reduces the seepage or loss of liquids from the filling, and other adverse changes to the filling or coating composition under typical room temperature storage conditions. Evidence of such undesirable water loss often is apparent in conventional products from cracks and disruptions in the chocolate coating, condensation of water within the chocolate coating and dampness or noticeable leakage from the product, as well as unexpected and undesirable microorganism growth.
While not wishing to be limited by theory, it is believed that the lower molecular weight sucrose substitutes are a sufficiently soluble in the water component in the filling to repress the aw of that component, and to permit the effective adjustment of the water activity of the filling composition. Therefore, alternative candidates for humectants usable in the invention may be selected based on the solubility of such products and their effect on the aw of the water component of the filling and of the filling composition.
The use of sucrose substitutes as humectants further permits the use of such sucrose substitutes as calorie reduction components of the filling. Many of the preferred sugar alcohols and monosaccharides useful as humectants also have a lower calorie content and a sweetener level sufficient to permit the reduction, and in some instances elimination, of the sucrose component of conventional confectionery fillings.
Other alternative sucrose substitutes include monosaccharides such as fructose and dextrose. Fructose is available in crystalline form and as high fructose corn syrups and also provides the potential for formulating a product acceptable to individuals with diabetic conditions. Monosaccharides such as fructose and dextrose typically have calorie values similar to sucrose, but may be used to adjust the sweetness levels of the filling to allow for the optimal use of lower calorie sucrose substitutes employed for calorie reduction and humectant purposes. Similarly, artificial sweeteners also may be used for similar purposes.
Thus, the sweetener level of the filling composition may be adjusted for specific applications by using a combination of two or more sucrose substitutes with different sweetener levels for the filling. In one embodiment, multiple sucrose substitutes are used for calorie reduction and as humectants, allowing tailoring of the fillings aw to a desired level. In this embodiment, the sucrose substitutes xylitol, malbit and dextrose are used in different proportions to provide filling compositions with increased or decreased sweetness levels depending on the expected use of the filling. By using greater proportions of malbit and dextrose, the sweetness levels are increased; and by reducing the malbit and dextrose amounts, and increasing the amount of xylitol, the sweetness level is decreased. Similarly, by the use of multiple sucrose substitutes, the aw of the filling is adjusted to an appropriate level by further adjusting the amounts of malbit and xylitol in the filling. Thus, as mentioned above, such sucrose substitutes can be used to both provide desired sweetener levels and to assist in providing the desired shelf-life for the confectionery product.
In one preferred embodiment, the fat mimetic is inulin or related inulin-based polysaccharides. These naturally occurring and commercially acceptable fat mimetics have organoleptic, texture, melting and gelling characteristics suitable for use in food production. The inulin component of the filling is preferably about 20% by weight of the filling, and may be up to as much as about 50% by weight of the filling, as long as the inulin provides sufficient gelling properties to provide a firm, commercially acceptable filling product for the intended confectionery product.
The preferred inulin is referred to as Raftiline ST which is available commercially from Raffinerie Tirlemontoise S.A., Belgium, and can be prepared with water to produce a stable creme-like composition having acceptable organoleptic, texture and gelling properties. In addition, other forms of inulin may be used depending on commercial availability of such products and the desired properties of the fat mimetic component of the filling composition. Other fat mimetics such as polymeric carbohydrates (e.g, polydextroses) and cellosic systems may be used as well, subject to their acceptance for use in food products and properties suitable for use in the filling of the invention. Thus, the choice of such alternative fat mimetics will depend on the desired texture, organoleptic, flavor, physical properties and desired shelf-life of the filling. In some instances, fat mimetics suitable for use in the filling also may be used as sucrose substitutes based on their sweetness levels and caloric contents.
The preferred inulin product Raftiline ST may be used in a dry powder or crystalline form for ease of handling, although other forms of that product also may be used. When properly blended with water, this inulin product provides an opaque gel which sets and becomes stiffer over time to provide advantages in handling and dispensing of the filling during the production of the confectionery product. It generally is desirable to provide a filling that becomes stiffer and firmer in storage once filling is covered with a confectionery coating or dispensed into a confectionery shell. Furthermore, this gelled component provides desirable water retention, texture and organoleptic properties to the filling composition.
The flavoring component of the preferred filling composition typically provides the primary or dominant contribution to the overall flavor profile of the filling. The flavoring component preferably is prepared from a mixture of a generally water insoluble flavoring ingredients such as cocoa liquor mixed with a hazelnut paste. In that preferred embodiment, the water insoluble cocoa liquor and hazelnut paste flavoring mixture may be emulsified with the water soluble components of the filling or may be used to form a flavoring emulsion that may be combined with the other, water soluble components. This flavoring component preferably is about 10% to about 30% by weight of the filling and more preferably is about 20% by weight of the filling.
The flavoring component may include other flavoring compositions and oils such as fruit flavorings, chocolate substitutes, nut flavorings or other similar products conventionally used to flavor confections, including water soluble flavorings. In one such preferred embodiment, other flavor components such as caramel flavoring, butter and butter flavorings, and similar flavor modifiers are used in conjunction with cocoa liquor and hazelnut paste to provide a desired flavor profile for a specific application.
Other components of the filling (as well as the coating) also may affect the flavor profile of the confection. For example, in milk chocolate flavored fillings, the milk ingredient of the filling provides an important contribution to the overall flavoring profile. Thus, the amount of flavoring component used in the filling may be varied depending on the flavor profile desired for the confectionery product and the flavoring contributions of other ingredients of the confection.
In a preferred embodiment, the inulin or inulin based products used as a fat mimetic also act as an emulsifier for incorporating the flavoring components into the filling composition. Thus, in this preferred embodiment, the inulin component serves both to provide desirable organoleptic, texture and gelling characteristics, and as an important emulsifying component of the mixture used to provide the desired flavor profile to the filling composition. Other protein and non-protein emulsifiers also may be used depending on the desired filling properties and application.
As previously mentioned, the texture of the preferred embodiment of the filling is determined in significant part by the properties of the inulin and sucrose substitute components used in formulating the filling. The texture and mouth feel of the filling also may be modified by the use of starches, starch maltodextrines, and other starch systems such as those derived from tapioca, potato, rice and corn products. Various proteins also may be employed to modify the texture and mouth feel of the fillings, such as those derived from egg whites, low bloom gelatins, casein, milk protein isolates and milk.
For food safety purposes, preservatives may be added to the product including sorbates and other conventional preservatives that are used in small amounts and will not adversely effect the flavor, organoleptic or texture properties of the confectionery product.


A process and apparatus for preparing the process for reducing the power consumption of microprocessor-based devices by reducing the frequency of the oscillator governing the logical operation of the microprocessor during periods of use in which system performance is not critical. In one embodiment of the apparatus, the microprocessor is controlled by a monitor circuit operable with the microprocessor and operated by the variable frequency oscillator. In another embodiment a hardware monitor circuit is utilized and which tracks microprocessor instructions to determine periods of use when performance is not critical. The shift in oscillator speed is mediated by a flip-flop latch circuit connected between one or more clock oscillators and the oscillator input of the controlled microprocessor.

The present invention relates to a method and apparatus for reducing power consumption of a microprocessor based device which is designed to operate from a stored energy source so as to extend the useful life of the stored energy source and therefore the ability to use the microprocessor based device. More particularly, the invention relates to a method and apparatus which reduces the power usage of the microprocessor itself during periods of inactivity or where the full extent of the microprocessor""s capabilities are not necessary for the tasks being performed on the device. The reduction in power usage of the microprocessor is accomplished automatically based upon determinations of such inactivity or other predetermined conditions.
There are a growing number of portable microprocessor-based devices such as laptop computers, which are designed to run on batteries far from utility lines. In these systems, power consumption has been a primary factor limiting system design. Without adequate battery life, normal processing tasks cannot be completed in the operating time available. Consequently, most aspects of the design of portable microprocessor-based devices have been optimized to conserve battery power. The power required by display systems, disk memory, and support circuitry have all been reduced. The known methods used to conserve power are two: first, to develop components that consume less power, and second, to interrupt or suspend component operation during period""s of inactivity. These two methods are effective for all components except the microprocessor itself.
Power savings have been achieved in display systems by the above two strategies. The technologies used for screen displays have shifted from those consuming large power such as cathode ray tube, light emitting diode, and gas-plasma displays, to those with more modest power requirements, principally liquid crystal displays with or without backlighting. In addition, circuitry has been introduced to microprocessor-based devices to automatically shut off the screen, thereby conserving the power that it would use during lengthy periods of system inactivity.
Inactivity is typically determined by the absence of change in the data displayed on the screen or typed at the keyboard of a microprocessor-based device. The power consumed by disk drives has been reduced by using newer designs that are smaller and more energy efficient. In addition, hard disk drives, which normally consume power continuously because their magnetic media must be kept constantly spinning, have been devised which automatically stop their rotation after a predetermined period of microprocessor-based device inactivity. Inactivity is determined by the absence of commands to store data on or retrieve data from the storage medium.
Although these steps have helped to extend the usefulness of portable microprocessor-based devices, there has also been a trend to put increasingly powerful microprocessors into the machines. This exacerbates the battery power drain because more powerful microprocessor-based devices are more complicated, have more internal circuitry, and naturally consume more energy. For example, the Intel 80386 microprocessor comprises about 375,000 separate internal transistors; the newer 80486 comprises over a million, and even newer devices in the future will necessarily be comprised of even larger numbers.
Microprocessor power reduction has been achieved in some portable microprocessor-based devices such as those based on the 8088 and 80286 made by Intel Corporation by using special designs based on low-power Complementary Metal Oxide (CMOS) semiconductor technology, which is an inherently more power-efficient technology than other common semiconductor technologies. As a result, the power required by the microprocessor in such devices is not as large a fraction of the total power required by the entire microprocessor-based system.
However, the more powerful the microprocessor, the greater the fraction of system power resources must be devoted to its operation. The 80386 microprocessor, for instance, can consume five to eight watts, which is more than the total consumption of all the circuitry and components in a less powerful microprocessor-based device combined. Yet more powerful portable microprocessor-based devices, such as those based on the Intel 80386 and other advanced designs already use CMOS internal circuitry. The effects of utilizing more powerful microprocessors such as the Intel 80386 can be seen in one known portable lap-top computer utilizing the 80386 microprocessor which will have a typical operatic time of xc2xd hour before the battery life of the device is exhausted. This assumes that the computer is being used, At least to some degree, for computing tasks which will consume more power than the simple house keeping functions of the microprocessor. In the known laptop computer, the microprocessor is operated at a relatively slow speed of 12.5 MHz., to try and extend the useful life of the device, but also results in non-efficient operation of the device.
Moreover, the other traditional power saving techniques cannot be applied to the microprocessor. The microprocessor cannot be stopped during periods of inactivity. When the microprocessor stops its operation, the microprocessor-based device itself stops operating and is unable to detect when to resume operation when activity is resumed. Also as mentioned before, the microprocessor is never completely inactive. In all practical microprocessor-based devices, the microprocessor constantly engages in housekeeping functions. It continuously executes instructions to monitor the data-input devices, such as sensors or keyboards, as well as its input and output ports for new data input.
This monitoring process typically involves repeatedly executing a looping string of instructions. Stopping the operation of the microprocessor would halt the execution of those instructions necessary for monitoring the system, depriving the microprocessor of the ability to restart itself. Consequently, all current portable microprocessor-based devices must necessarily keep the microprocessor operating at all times.
It is also recognized that the power consumed by a microprocessor is directly related to the frequency of the oscillator driving it. During normal operation, the circuitry inside a microprocessor is constantly active: transistors continuously change state to execute logic operations as governed by the oscillator. Each change of state necessarily consumes a fixed and predetermined amount of power. The more often state changes take place; the more power is consumed by the microprocessor. On the other hand, reducing the oscillator speed also degrades the data processing ability of the microprocessor, contrary to the primary design goal in using a more powerful microprocessor which is to improve performance through higher operations speeds. Thus, unfortunately, the consequence of greater microprocessor speed, and better, more desirable performance characteristics, is greater power consumption.
There are also known in the prior art computers and other devices which are capable of multi-speed operation such is found with a xe2x80x9cturboxe2x80x9d function associated with some personal computers. These devices essentially operate at a normal operating speed under most circumstances but may be changed to operate at a higher speed for compatibility with software which is speed critical. In order to change the operating speed in these devices, a switch or instruction given by the user through the keyboard or other input device will manually convert the speed of operation dependent upon the user requirements. In such a system, the multi-speed operation does not reflect upon power usage of the device as such devices are not designed to be portable and run from a battery or other stored energy source.
Based upon the foregoing, it is a main object of the invention is to reduce the power consumption of microprocessor. Based devices through the application of a specific process and apparatus to perform said process which reduces the frequency of the oscillator driving the microprocessor automatically during the periods in which it is performing non-critical operations. That is, microprocessor speed reduction during periods in which all of the-data processing ability of the microprocessor-based device is not demanded.
It is another object of the invention to provide a method of reducing the power consumption of a microprocessor-based device wherein the microprocessor itself is utilized to determine periods of inactivity or other predetermined conditions to reduce the microprocessors operating speed accordingly.
It is yet another object of the invention to provide the process and apparatus to reduce the power consumption of a microprocessor-based device by utilization of an external circuit which-may be incorporated into the device to determine periods of inactivity or other predetermined conditions to reduce the operating speed automatically.
A further object of the invention is to provide a method and apparatus to reduce the power consumption of a microprocessor-based device which utilizes the occurrence of critical instructions or non-critical instructions or the reoccurrence of non-critical instructions to determine periods of activity or inactivity respectively, from which the operating speed of the device may be automatically changed accordingly.
These and other Objects are realized using the apparatus of the present invention which may be comprised of three parts in addition to the typical circuitry of a microprocessor-based device: a monitoring module, an oscillator latch, and a source of multiple oscillator frequencies.
The monitoring module may be implemented either as a defined process running on an unmodified microprocessor such as the Intel 80386 (or any improved future microprocessor design), as a hardware circuit connected to the data lines of this or any other microprocessor, or as a hardware code internalized inside the microprocessor.
The monitoring module may serve the functions of determining periods of non-critical use and the onset of critical use of the microprocessor. Periods of non-critical use are determined by the lapse of a predetermined time period without the occurrence of a critical defined command (specific interrupts or other predetermined instructions) or the repetition of a pattern of non-critical instructions for a given number of iterations (for example, instructions for polling a keyboard, parity-checking a spreadsheet, or polling sensor devices). The onset of critical use is determined by the occurrence of certain defined interrupts or instructions in the sequence read by the microprocessor.
The monitoring module controls a bi-state logic latch, the second part of the apparatus which selects between two sources for the oscillator frequency to be delivered to the microprocessor. When the latch receives an indication of critical use from the monitoring module, it selects the higher oscillator frequency. Alternatively, when it receives an indication of non-critical use, it selects the lower oscillator frequency.
In its most elementary form, the source of multiple oscillator frequencies is a standard oscillator circuit coupled to a simple frequency divider. Such a design assures that the two oscillator frequencies are constantly synchronized. More design freedom is afforded by using two separate, independently-operating oscillators, which need not be related in frequency. In this case, however, the oscillator latch must incorporate additional logic to match oscillator cycles to maintain an acceptable duty cycle during the switching period.

Process and apparatus for reducing power usage in microprocessor devices according to the type of activity performed by the microprocessor


A table has two end legs arranged in a parallel, laterally spaced apart relationship for support on a floor surface. Two side rails are arranged in a parallel, laterally spaced apart relationship, and are connected with upper portions of the end legs to retain them in an upright orientation, defining a self-supported table frame without intermediate bracing between the side rails, with a central, vertically extending widow. Top support members are connected with the side rails and protrude outwardly therefrom in a cantilevered fashion. A top member is supported on and connected with the table frame and the top support members, defining a plurality of workstations. A utility module configured to route utilities is positioned within the window of the frame, with opposite sides abuttingly supported on the side rails to removably mount the utility module on the frame and thereby accommodate different utility requirements at the workstations.

The present invention relates to furnishings for open office spaces and other similar environments, and in particular to a table construction therefor.
Elongate tables and worksurfaces, such as those used for conference tables, library tables, trader desks, and the like are generally well known in the art. More recently, such tables have been equipped with selected utilities, such as power and data, to support computers, telephones, video equipment and other similar electronic devices that are used on the table. Preferably, power and data ports or connections are positioned along the table for easy user access when working with a computer or like electronic device. While such prior tables have been generally effective, they are not particularly adaptable, and can not be readily reconfigured or expanded to meet different needs and/or users.
Changing technology and changing work processes demand that current office furnishings be readily adaptable to efficiently support the ever-changing needs of workers. Therefore, the quick and easy reconfigurability of a worksurface system is desired to meet these needs. A more recent challenge for such office furnishing is created by the increased use of hotelling, wherein many mobile staffers do not have a permanently assigned office, but rather reserve shared space at the various locations in which they work. These transient workers require even more adaptability in their shared work space to effectively perform tasks in an efficient manner. Hence, office furnishings capable of supporting multiple transient workers in a cost effective manner with minimum floor space are very beneficial, particularly when they can be readily adapted and reconfigured to provide important utilities at each of the various workstations.


A hydraulic binder, includes cement, and a mixture added to the cement and made of moist green vitriol and an inert carrier substance in the form of silica gel or alumina.

This application claims the priority of European Patent Application, Ser. No. 02 017 886.9, filed Aug. 9, 2002, pursuant to 35 U.S.C. 119(a)-(d), the disclosure of which is incorporated herein by reference.
The present invention relates, in general, to a hydraulic binder, and more particularly to a carrier substance for use in a hydraulic carrier.
Cement is typically used in the construction industry as finely ground hydraulic binder for making concrete mortar, concrete stones and finished parts. Oftentimes, cement is manually processed. This is disadvantageous because typical cement contains chromate which can trigger allergic reactions such as skin eczema, so-called cement dermatitis or bricklayer scabies.
Chromate-containing cement includes up to 100 pp, chromium(VI) compounds (chromates) of which about 20% are soluble. Soluble chromate is the cause of the allergic cement eczemas. By utilizing cement which is almost free of chromate and cement-containing preparations that are low in chromate, for example, tile adhesive or dry mortar, diseases of this type can be effectively eliminated. For that reason, cement-containing materials which are handled manually are produced exclusively with low content of chromate. Chromate-containing cement means a cement which contains less than 2 ppm water-soluble chromium(VI) relative to the dry mass.
It is known, to decrease the chromate content in cement through addition of a reducing agent, e.g. iron(II) sulfate. German patent publication no. DE 197 44 035 A1 describes the addition of dry iron(II) sulfate particles to cement at an amount of 0.01 to 1 wt. %, when the cement is withdrawn from a large silo. During preparation of the mortar or concrete mixture, the granular iron(II) sulfate dissolves in the mixing water and contacts the chromate(VI) during mixture to thereby chemically reduce it.
Also Manns, W.; Laskowski, Ch. describe in an article, entitled Eisen(II)sulfat als Zusatz zur Chromatreduzierung [Iron(II) sulfate for chromate reduction] in BE-Z: Beton [Concrete], journal 2/1999, pages 78-85, the use of dry pulverulent iron(II) sulfate for chromate reduction.
Dry iron(II) sulfate looses, however, effectiveness as a result of oxidation with atmospheric oxygen. Therefore, iron(II) sulfate has been added to cement only at a time when the cement is withdrawn from the large silo to thereby decrease the risk of undesired reaction as the granular iron(II) sulfate is added to the cement.
German patent publication no. DE 100 14 468 A1 describes the production of a building material made from a mixture of cement, water and additives and the addition of moist iron(II) sulfate, so-called green (iron) vitriol, to the mixture. Moist green vitriol has the same reduction qualities with respect to chromium(VI) compounds as dry iron(II) sulfate particles, but is significantly more cost-efficient and is in full compliance with all regulations.
To improve handling of moist green vitriol, an inert carrier material is added. Commonly assigned utility model DE 201 19 021, issued on Jan. 31, 2002, by the same inventive entity, and entitled xe2x80x9cHydraulisches Bindemittelxe2x80x9d [Hydraulic Binder], describes the use of ground limestone as carrier substance. Practice has shown, however, that the addition of green vitriol causes problems during metering and the inert carrier substance adversely affects the processing of the finished building material as a result of its grain size.
It would therefore be desirable and advantageous to provide an improved hydraulic binder which obviates prior art shortcomings and which is easy to make and to use while still being almost free of chromate.
According to one aspect of the present invention, a hydraulic binder includes cement, and a mixture added to the cement and made of moist green vitriol and an inert carrier substance in the form of silica gel or alumina.
The use of inert carrier substance within the mixture assumes the function of a drying agent and a moisture buffer. Mixture of the moist green vitriol with the carrier substance in the form of silica gel or alumina provides this mixture with the required properties for use in cement. The drying and buffer action of the carrier substance ensures an optimal setting of the green vitriol. Oxidation with atmospheric oxygen as well as lumping is avoided. The mixture can be added to cement and mixed therewith, without encountering lumping. Iron(II) sulfate is dissolved in the mixing water only during preparation of a mortar mixture or concrete mixture and then contacts chromate(VI) to reduce it chemically.
Screening of the mixture to the desired grain size or fineness is realized in suitable processing devices, such as mills, e.g., ball mils. Material can then be prepared in a fairly simple manner and added to cement without any problems.
According to another feature of the present invention, the mixture may have a graining with a residue of maximal 30%, preferably maximal 20%, on a sieve of 0.2 mm mesh. A fine-grained mixture is easier to meter and better to process.
The inert carrier substance according to the present invention is fine-grained or powdery and may be made of silica gel or alumina. Silica gel involves a solid amorphous silicic acid which is known for use as adsorption agent for gas, vapor and liquids and can be made with pores of different diameter. Silica gels exhibit a large inner surface, which may range up to 800 m2/g, to absorb liquid.
Silica gel can be manufactured synthetically as condensation product from silicon dioxide. Hereby, sodium silicate may be mixed with a mineral acid, e.g. sulfuric acid. A sol (SiO2, Na2SO4, H2O) is produced from these materials and allowed to solidify to form jelly. Sodium sulfate, obtained from comminuted jelly pieces, is then washed out. Different properties, such as pore volume, pore diameter and inner surface may be implemented through suitable control of the washing process with different pH values, temperatures and other parameters. The washed product is called hydrogel and is transformed after drying to silica gel as uneven granulate.
The use of silica gel for use as carrier substance is currently a preferred embodiment for mixture with green vitriol.
Silica gel contains as main ingredient silicate (SiO2) and further includes aluminum (Al2O3), sodium (Na2O), sulfate (SO4) as well as iron (Fe2O3), potassium (K2O), lanthanum (La2O3), ammonium (NH4+), chloride (Clxe2x88x92) and cerium (Ce2O3). Also calcium (Ca) and magnesium (Mg) may be contained.
The inert carrier substance may also be made of alumina, in particular activated alumina. Activated alumina is activated aluminum oxide (Al2O3). Involved here is a natural clay mineral (bentonite) in crumbly form with similar adsorption capability for moisture as silica gel.
According to another feature of the present invention, the mixture of green vitriol and a carrier substance in the form of silica gel or alumina may further include at least one additive selected from the group consisting of zinc, aluminum, phosphorus, and titanium oxide. In this way, the mechanical properties, e.g. toughness or flow behavior, of the building material produced with the assistance of the hydraulic binder according to the present invention can be adjusted. Zinc, for example, promotes strength and is added at an amount of less than 10 wt. %. Phosphorus may be used to delay the solidification time of the cement, and may also be added at an amount of less than 10 wt. %.
According to another feature of the present invention, the mixture of green vitriol and a carrier substance in the form of silica gel or alumina may be added to the cement at an amount between 0.01 wt. % to 5 wt. % in relation to the amount of cement. In this way, the chromate content is effectively reduced to below the level that poses a health hazard.
According to another feature of the present invention, the carrier substance is contained in the mixture at an amount between 5 wt. % to 15 wt. % in relation to the amount of green vitriol.

Carrier substance for a hydraulic binder


The invention relates to a process for producing amplified negative resist structures in which, following exposure and contrasting of the resist in a developing step, the resist structure is simultaneously developed and silylated. This substantially simplifies the production of amplified resist structures.

The invention relates to a process for producing amplified negative resist structures.
In the fabrication of microchips, semiconductor substrates are structured (or patterned) using thin layers of photoresists. The chemical nature of the photoresists can be selectively altered by exposing the photoresists using a photomask or by direct irradiation, with an electron beam, for example. Following a developing step, in which either the exposed or the unexposed areas of the photoresist are removed, a structured photoresist is obtained that is used as a mask for etching the semiconductor substrate, for example. In the case of dry etching, the etching operation is usually carried out with a fluorine or an oxygen plasma. In order to selectively etch only the bare areas of the substrate, therefore, the mask-forming resist structure must possess sufficient resistance to the plasma that is used. When using an etching plasma containing oxygen, the photoresist therefore usually includes groups containing silicon. In the course of the etching operation, these groups are converted into silicon dioxide, which forms an etch-stable protective layer on the photoresist. The silicon atoms either may already be present in the photoresist polymer or may be introduced into the polymer subsequently, following the development of the resist structure, in a consolidation reaction. For this purpose, reactive groups are provided, such as acid anhydride groups, carboxyl groups or acidic phenolic hydroxyl groups, to which the amplifying agent, which carries a corresponding reactive group, an amino group for example, can be chemically attached.
In order to be able to realize low exposure doses and short exposure times when exposing the photoresist, photoresists known as chemically amplified resists (CARs) have been developed. In this case the photoresist includes a photosensitive compound that liberates a catalyst on exposure. In a subsequent amplifying step, the catalyst is able to bring about a chemical reaction that gives rise to a marked change in the chemical nature of the photoresist. With a single quantum of light, which liberates one catalyst molecule, it is therefore possible to bring about a multiplicity of chemical reactions and to achieve a marked differentiation between the exposed and unexposed areas of the photoresist. The catalyst used is usually a strong acid that is liberated by a photoacid generator, an onium compound for example. The polymer contains acid-labile groups, such as tertiary butyl groups, which are eliminated under the action of the acid liberated. The elimination of the acid-labile group is generally accompanied by the liberation of an acidic group: for example, a carboxyl group or an acidic hydroxyl group. This brings about a marked change in the polarity of the polymer, i.e., in its solubility in polar solvents. The polymer originally used in the photoresist, carrying acid-labile groups, is soluble in apolar solvents or solvent mixtures having a low polarity, such as alkanes, but also in alcohols, ketones or esters, whereas the polymer following elimination of the acid-labile groups is soluble in polar solvents, generally water or basic, aqueous-organic developer solutions.
In connection with the production of resist structures, a range of processes have already been developed, which can be divided into two groups.
In the case of positive photoresists, the exposed areas of the photoresist are detached in the developing step and in the structured photoresist, for example, form trenches, whereas the unexposed areas remain on the substrate and form the lines of the photoresist structure.
For producing positive photoresist structures, the procedure described above can be followed. As a result of the exposure, a chemical reaction is initiated within the photoresist, by means of which the photoresist polymer becomes soluble in alkaline developer solutions: for example, a 2.38% strength solution of tetramethylammonium hydroxide in water. On development, then a corresponding positively structured photoresist is obtained.
In the case of negative resists, in contrast to the positive-working resists, the exposed portion of the resist remains on the substrate, whereas the unexposed portion is removed by the developer solution. When working with chemically amplified negative resists, exposure initially likewise liberates a catalyst, usually a strong acid. The catalyst brings about, for instance, a crosslinking reaction in the photoresist, as a result of which the solubility of the polymer in the developer medium is reduced. As a result of the crosslinking, the exposed area becomes insoluble, whereas the unexposed area can be removed in appropriate developers. Developers used are generally aqueous solutions, so that the polymer usually has polar groups in the unexposed state.
For a modification of the developing step, a positive photoresist can also be used to produce a negative resist structure. A process of this kind is described, for example, in U.S. Pat. No. 4,491,628. There, a layer of a positive photoresist that is applied to a substrate is first of all exposed as described above, and an acid is liberated from a photoacid generator. In the subsequent amplifying step, the acid-labile groups in the exposed areas are eliminated by heating, so that the polymer is then in a polar form. In contradistinction to the positive developing process described above, exposure is not carried out with a polar aqueous developer, but instead with an apolar solvent. As a result, only the unexposed areas of the substrate, in which the polymer has retained its original apolar form, are detached. Since the polar fractions of the resist, in which the polar groupsxe2x80x94carboxylic acid groups, for examplexe2x80x94have been produced by the exposure, are insoluble in apolar solvents, they remain as lines on the substrate.
Another negative photoresist includes not only a photobase, but also a thermoacid. A resist of this kind is described, for example, in Published PCT Patent Application PCT/DE00/04237. On exposure of the photoresist, a base is liberated in the exposed areas. In a subsequent amplifying step, an acid is liberated from the thermoacid generator by heating. In the exposed areas the acid is neutralized by the base being liberated beforehand and is therefore no longer available as a catalyst. In the unexposed areas, the acid catalyzes the elimination of the acid-labile groups from the polymer. Accordingly, in the unexposed areas, the polymer is converted from its apolar form into a polar form. In the subsequent developer step, therefore, the unexposed areas can be selectively detached from the substrate using an aqueous-alkaline developer, while the exposed areas remain as lines on the substrate.
As already mentioned, for etching the substrate, the resist structure must possess sufficient etch resistance. For this purpose, for instance, the lines of the resist structure must have a sufficient layer thickness. This is a particular problem in the case of resists for the 157 nm and the 13 nm technology, since at these wavelengths the photoresists known to date exhibit high absorption. Accordingly, only very thin polymer films can be used, in order to ensure that the radiation used for exposure is able to penetrate even into the deep areas of the resist in sufficient intensity, in order to be able to liberate sufficient quantities of catalyst. If insufficient quantities of catalyst are liberated in the lower layers of the photoresist, elimination of the acid-labile groups is incomplete, or in a worst case scenario, does not take place at all. A consequence of this is that following development residues of the polymer remain in the trenches, forming what are known as resist feet. Because of its low layer thickness, the resistance of the structured photoresist to an etching plasma is insufficient, which is why its etch resistance must be increased. For this purpose, following development, the structured resist is chemically amplified. Where the resist structures have a sufficient layer thickness, it is also possible, in addition to an increase in layer thickness, to bring about a narrowing of the trenches, perpendicularly to the substrate surface, by laterally growing layers on the sidewalls of the trenches of the structured resist. As a result it is possible to achieve an improvement in resolution: that is, for example, the reproduction of narrower conductor tracks. A process of this kind is described, for example, in Issued European Patent EP 0 395 917 B1. In order to amplify the resist structure, the amplifying agent in solution in a suitable solvent or else in the gas phase, can be applied to the structured resist. The incorporation of silicon-containing amplifying agents into the polymer is generally referred to as silylation.
The existing processes for producing amplified resist structures involve a multiplicity of worksteps and are therefore very complicated to carry out. Every workstep also increases the error rate in the fabrication of microchips, meaning that a correspondingly high rejection rate must be tolerated. This is also a problem on account of the fact that nondestructive testing is not possible at every step in microchip fabrication. Generally, error testing of this kind is possible only after several production steps, since it is only then that the electrical connections necessary for testing are present in the microchip. In some circumstances, therefore, several weeks may pass between the production step and error testing. Accordingly, an extremely low error rate is required for each production step.
The chemical consolidation requires corresponding reactive xe2x80x9canchorxe2x80x9d groups in the polymer, to which the amplifying agent can be attached. Preparation of these polymers necessitates processes that are likewise complex, since, for example, they must be carried out in the absence of moisture in order to prevent premature hydrolysis of the reactive anchor groups.
It is accordingly an object of the invention to provide a process for producing amplified negative resist structures that is easy to carry out and that has a lower error rate as compared with the existing processes.
With the foregoing and other objects in view there is provided, in accordance with the invention, a process for producing amplified negative resist structures. The process includes steps of: providing a chemically amplified resist including: a polymer including acid-labile groups, which on exposure to an acid, are eliminated and liberate anchor groups bringing about a change in a polarity of the polymer, a photoacid generator, and a solvent; applying the chemically amplified resist to a substrate; removing the solvent to provide a photosensitive resist film; sectionally exposing the resist film to liberate an acid from the photoacid generator in exposed sections of the resist film; and contrasting the exposed resist film such that the acid-labile groups of the polymer are eliminated by the acid, which has been liberated, and the anchor groups are liberated in the exposed sections of the resist film. The process also includes developing the exposed resist film, which has been contrasted, with a developer including: a solvent in which the polymer, when in a state including the acid-labile groups, is soluble and in which the polymer, when in a state after the anchor groups have been liberated, is substantially insoluble or swellable, and a silicon-containing amplifying agent including at least one reactive group that is able to coordinate to the anchor groups of the polymer. In addition, the process includes removing excess developer.
In accordance with an added feature of the invention, the developer includes a swelling promoter that swells the polymer when in the state after the anchor groups have been liberated.
In accordance with an additional feature of the invention, the solvent of the developer is apolar.
In accordance with another feature of the invention, the solvent of the developer has a low polarity.
In accordance with a further feature of the invention, the polymer includes further reactive anchor groups that are able to form a bond with the reactive group of the amplifying agent.
In accordance with a further added feature of the invention, the amplifying agent includes at least two reactive groups.
In accordance with yet an added feature of the invention, the reactive group of the amplifying agent is a basic group.
In accordance with yet an additional feature of the invention, the amplifying agent is an aminosiloxane.
In the process, the resist structure is developed and is amplified with a silicon-containing amplifying agent in one conjoint step. As a result, in comparison to the existing processes, the development of the resist structure with a suitable developer medium in a separate workstep is omitted, together with the subsequent rinsing and drying step. As a result, there is a corresponding reduction in the error rate associated with the production of amplified structured resists. The process of the invention is easier to carry out than the processes used to date and therefore results in a reduction in costs. The process can be carried out using the photoresists customary for producing positive resist structures and the customary silicon-containing amplifying agents. Implementation of the process of the invention into existing production lines requires no special effort apart from a change in the solvent used for developing and amplifying.
Polymers which can be used for the photoresist are those which following exposure and contrasting, liberate a reactive group which is able to enter into reaction with the amplifying agent. The reaction may lead to the formation of a covalent bond between an anchor group and the amplifying agent. However, the amplifying agent may also be attached to the anchor group of the polymer by noncovalent bonds, e.g., ionic interactions or dipole-dipole interactions. Suitable therefore, for example, are the polymers customary for positive photoresists. The polymers must have adequate film-forming properties to be able to produce a uniform film of the photoresist on the substrate. Any polymer can be used which possesses, in the polymer chain or pendantly, acid-labile groups of low alkali solubility which generate reactive groups, such as acidic groups, on the polymer as a result of the catalytic effect of acid, and where appropriate, a simultaneous temperature treatment (contrasting). Examples of suitable acid-labile groups include tert-alkyl ester, tert-butoxycarbonyloxy, tetrahydrofuranyl, tetrahydro-pyranyl, tert-butyl ether, lactone or acetal groups. Tert-Butyl ester groups are particularly preferred. The polymer preferably contains groups which bring about increased transparency of the polymer (and hence of the resist layer) to light of a very short wavelength, 157 nm for example. Such groups are 1,1,1,3,3,3-hexafluoro-2-hydroxy-isopropyl groups, for instance, in which the hydroxyl function is substituted by a tert-butyl ether, tert-butoxy-carbonyloxy, tetrahydrofuranyl, tetrahydropyranyl or acetal radical or by another acid-eliminable radical.
The film-forming polymer may be obtained by polymerization or copolymerization of corresponding monomers. Examples of monomers include acrylates, methacrylates, maleic monoesters and diesters, itaconic monoesters and diesters, norbornenecarboxylic esters or else norbornenedicarboxylic monoesters and diesters. Corresponding repeating units of the polymer are depicted below. Y stands for an acid-labile group, one of the abovementioned groups for example, and R1 stands for a non-acid-labile radical, an alkyl group having from 1 to 10 carbon atoms, for example.
These monomers can be copolymerized with further monomers which may also already include silicon-containing groups. One suitable silicon-containing monomer, for example, is allyltrimethylsilane. Other suitable copolymerisable monomers are, for example, styrene or methyl methacrylate. Besides the monomers mentioned, it is also possible to use other monomers customary for the preparation of polymers for photoresists.
As photoacid generators it is likewise possible to use the photoacid generators which are customary for photoresists. Preference is given to using onium compounds, as described, for example, in European Patent Application EP 0 955 562 A1.
Resist solvents which can be used include, for example, methoxypropyl acetate, cyclopentanone, cyclohexanone, xcex3-butyrolactone, ethyl lactate, diethylene glycol dimethyl ether, or a mixture of at least two of these compounds. In general, however, all common solvents, or mixtures thereof, which are capable of taking up the resist components in a clear, homogeneous, and storage-stable solution can be used, which ensure good layer quality when the substrate is coated.
The photoresist is applied to the substrate by the conventional techniques, such as by spincoating, spray application or dipping methods. The solvent is subsequently removed by conventional methods. For this purpose, generally speaking, the substrate with the resist film is heated.
Thereafter, the resist film is exposed, for which purpose again the conventional methods can be employed. Exposure may take place, for example, by means of a photomask or else by direct exposure with focused electrons or ions. The exposing radiation preferably has a wavelength in the range from 10 to 400 nm. In the exposed areas, the photoacid generator liberates an acid, so that a latent image of the desired structure is generated. Exposure of the resist film is followed by a contrasting step in which the latent image is intensified and is impressed into the polymer of the photoresist, so that the photoresist now has a chemical profile. For this purpose, the substrate with the exposed resist film is heated, generally at temperatures from 80 to 200xc2x0 C. Under the catalytic effect of the acid, the acid-labile groups on the polymer are eliminated and the anchor groups for the attachment of the amplifying agent are liberated. The anchor groups generally have a high polarity, which is why the polymer now likewise has a high polarity and hence a high solubility in polar solvents or a low solubility in apolar solvents. The process of the invention then utilizes the difference in polarity of the polymer in the exposed and unexposed state, in other words its different solubility in the solvent. Where the polymer contains acid-labile ester groups in the unexposed state, then following exposure and contrasting it contains carboxyl groups. The polymer in the unexposed state, therefore, is comparatively apolar and is soluble in apolar or weakly polar solvents, whereas the polymer following exposure and contrasting has a polar nature and is therefore insoluble in apolar or weakly polar solvents. This difference in solubility is then utilized in the developing step. The solvent is selected so that the polymer containing acid-labile groups is soluble and the polymer in which the anchor groups have been liberated is insoluble or swellable. As a result, in the developing step only the unexposed areas of the substrate are detached and in the unexposed areas, structures are formed in which the substrate is bare. The developer further contains a silicon-containing amplifying agent which has at least one reactive group which is able to coordinate to the anchor groups of the polymer. The amplifying agent may therefore be attached to the exposed areas of the photoresist as early as during the developing step, and may act there to increase the layer thickness and etch resistance of the resist. Coordination of the amplifying agent to the polymer preferably takes place by the formation of a chemical bond between the anchor groups of the polymer and the reactive group of the amplifying agent, accompanied, for example, by the formation of an amide bond. Also possible, however, is the formation of a salt or the coordination of polar groups. The amide bond may also be formed such that first of all, in the developing/amplifying step, an ammonium salt is formed by the anchor group and the amplifying agent, and in a subsequent production step, e.g., during drying of the developed and amplified resist, heating is carried out, such that an amide bond between the polymer and the amplifying agent is formed with the elimination of water.
Solvents used for the developer include apolar or weakly polar solvents. All conventional aliphatic, cycloaliphatic, and aromatic solvents are suitable, such as alcohols, aldehydes, ketones, lactones or esters of low polarity, and also mixtures of the solvents. The solvents must take up the components of the developer in the form of an emulsion, or preferably in a clear, homogeneous, and storage-stable solution and must not react with the amplifying agent or with the anchor groups present on the polymer.
Following the development and amplification of the resist structure, excess developer is removed with an appropriate solvent and the resist structure is dried.
In order to ensure a reaction rate that is sufficient for practical application when attaching the amplifying agent to the polymer and to ensure a sufficient increase in layer thickness, the composition of the developer should be such that the resist is swollen by the developer in the exposed areas. This allows the-amplifying agent to penetrate relatively deep layers of the resist structure, and so permits better amplification. Swelling of the resist in the exposed areas may be achieved simply by an appropriate choice of solvents. If, however, the exposed and contrasted resist exhibits only a very low solubility in the developer solvent, or if it is insoluble in the solvent, it is possible to admix to the developer, a swelling promoter that swells the polymer in which the anchor groups are liberated. Suitable swelling promoters include low molecular mass polar compounds, such as water, for instance, low molecular mass alcohols, e.g., methanol and ethanol, and low molecular mass aldehydes and ketones, such as acetone, for instance.
As the silicon-containing amplifying agent it is possible to use any customary amplifying agents which include silicon-containing groups, provided these agents are of sufficient reactivity toward the anchor groups of the polymer and do not react with the solvent of the developer. The silicon-containing amplifying agent should be able to diffuse into the polymer at a rate that is sufficient for reaction in an industrial production process. The amplifying agent should therefore preferably have a molecular weight in the range from 100 to 2,000 g/mol.
Since the anchor group of the polymer is usually an acidic group, such as a carboxyl group or an acidic hydroxyl group, such as phenolic hydroxyl group, the reactive group of the amplifying agent is preferably a basic group. Particularly suitable in this context are amino groups, which are able to react, for example, with a carboxyl group to form an amide bond. The amplifying agent is preferably a silicon compound with basic functionalization, especially an aminosiloxane. Those which have proven particularly appropriate include catenated dimethylsiloxanes containing terminal aminopropyl units and from 2 to 50, but preferably from 2 to 12, silicon atoms per molecule. A catenated dimethylsiloxane of this kind is depicted below with its general structural formula.
Instead of the methyl groups it is also possible for other alkyl groups to be provided in the aminosiloxane, examples being ethyl groups or propyl groups. Further examples of amplifying agents containing amino-functional groups can be represented by the following general structural formula.
where R2xe2x95x90H, alkyl, aryl, cycloalkyl and R3xe2x95x90
A further very suitable reactive group in the amplifying agent is the isocyanate group. It is able to react, in particular, with hydroxyl groups that are present in the polymer.
The inventive process is preferably implemented in such a way that the solvent of the developer is apolar or has a low polarity. The polarity of the solvent relates in this case to its solvency for apolar or polar compounds, respectively.
In the inventive process, the polymer need not per se contain any more groups which serve as reaction anchors for the consolidation of the resist structure. Such anchor groups are formed in the contrasting step on the acid-catalyzed elimination of the acid-labile groups following exposure, in the form, for instance, of acid groups or (acidic) alcoholic groups. This has the advantage that the polymers are much easier to process, since they contain no groups that are sensitive to hydrolysis.
Preferably, however, in addition to the anchor groups protected by an acid-labile group, the polymers include further reactive anchor groups that are able to react with the reactive group of the amplifying agent to form a covalent bond. In this case, in the course of the amplifying step, there is an irreversible fixing of the amplifying agent on the polymer. Suitable for this purpose in particular are acid anhydride groups provided in the polymer, which are introduced into the polymer by copolymerization of unsaturated carboxylic anhydrides. Examples of suitable monomers are maleic anhydride, itaconic anhydride or methacrylic anhydride. The anchor groups liberated by the elimination of the acid-labile groups have the further function, in the case of this variant of the process, of raising the polarity of the polymer and so lowering the solubility of the polymer in the solvent of the amplifying agent.
These reactive anchor groups may also be utilized for further modification of the photoresist. By way of example, the insolubility of the exposed areas in the developer can be increased further if further crosslinking of the polymer is brought about. This can be achieved, for example, by the amplifying agent containing at least two reactive groups. Compounds suitable for this purpose include, for example, the diaminosiloxanes described already above.
The components described above are preferably used in the resist in the following proportions:
Film-forming polymer: 1-50% by weight, preferably 2-10% by weight;
Photoacid generator: 0.01-10% by weight, preferably 0.1-1% by weight; and
Solvent: 80-99% by weight, preferably 88-97% by weight.
The components described can be used in the developer in the following proportions:
Amplifying agent: 0.1-10% by weight, preferably 2-3% by weight;
Swelling promoter: 0.01-10% by weight, preferably 0.5-2% by weight; and
Solvent: 50-99% by weight, preferably 92-97% by weight.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a negative resist process with simultaneous development and silylation, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

Negative resist process with simultaneous development and silylation


In a method for minimizing thermoacoustic oscillations in gas turbine combustion chambers, an inert gas (N2, CO2, H2O) is additionally mixed with the stream of fuel.

The invention relates to a method for minimizing thermoacoustic oscillations in gas turbine combustion chambers.
is known that undesirable thermoacoustic oscillations often occur in combustion chambers of gas turbines. The term xe2x80x9cthermoacoustic oscillationsxe2x80x9d denotes thermal and acoustic disturbances which build up in opposition to one another. In this case, high oscillation amplitudes may occur, which may lead to undesirable effects, such as, for example, to a high mechanical load on the combustion chamber and increased NOx emissions due to inhomogeneous combustion, and even to the flame being extinguished. This applies, in particular, to combustion systems which have only little acoustic damping.
In conventional combustion chambers, the cooling air flowing into the combustion chamber has an important function, since the cooling air film on the combustion chamber wall has a sound insulating effect and therefore contributes to reducing thermoacoustic oscillations. In order to achieve low NOx emissions, in modern gas turbines an increasing proportion of the air is conducted through the burners themselves, that is to say the cooling air stream is reduced. Since there is consequently less sound insulation, therefore, the initially mentioned problems associated with the undesirable oscillations arise to an increased extent in such modern combustion chambers.
One possibility for sound insulation is for Helmholtz dampers to be coupled in the combustion chamber hood or in the region of the cooling air supply. If conditions of space are restricted, however, this being typical of modern combustion chambers of compact design, accommodating such dampers may present difficulties. This method therefore entails a high outlay in terms of construction.
In addition, it is known that the fluidic stability of a gas turbine burner is of critical importance for the occurrence of thermoacoustic oscillations. The fluidic instability waves occurring in the burner lead to the formation of vortices. These vortices, also designated as coherent structures, play an important part in mixing processes between air and fuel. The dynamics of the coherent structures influence, combustion and the associated release of heat. These vortices may therefore lead to a periodic release of the heat of the burner flame and therefore to pressure fluctuations. Particularly when there is no homogeneous intermixing of fuel and air over the entire surface of the burner, the occurrence of coherent vortex structures has a pronounced effect on the formation of thermoacoustic instabilities.
A further possibility for reducing the tendency of a burner to oscillate is therefore to prevent or at least reduce the vortex formation described above. This leads to an improvement in the intermixing of fuel and air and to a reduction in the tendency of the burner to oscillate. In this respect, the type of fuel injection exerts a decisive influence on the mixture quality and therefore on the position and shape of the flame which is established.
Accordingly, one object of the invention is to provide a novel method for minimizing the pressure amplitude of thermoacoustic oscillations in gas turbine combustion chambers. This object is achieved, according to the invention, by means of the method for minimizing the pressure amplitude of thermoacoustic oscillations in a gas turbine according to the invention.
According to the invention, an additional inert gas is mixed in with the fuel stream of the gas turbine burner. The fuel/air pulse ratio is thereby increased, thus leading to a reduction in the formation of coherent structures and to improved intermixing of the fuel/air mixture. In the method according to the invention, therefore, a reduction in the thermoacoustic oscillations can be achieved by varying the quantity of mixed-in inert gas at the gas turbine.
The decrease in pulsations, along with a controlled addition of inert gas, reduces the emission of NOx. The decrease in the emission of NOx is, in this case, proportional to the decrease in the pressure oscillation amplitudes.
Within the scope of the present invention, the term xe2x80x9cinert gasxe2x80x9d is used with regard to the combustion operation taking place in the burner. This means that the inert gas additionally mixed in does not participate in the chemical reactions which take place during the combustion of the fuel. Gases which satisfy the abovementioned preconditions are, for example, nitrogen, carbon dioxide or steam. These gases or else to the present invention. In addition, however, other gases which do not react under the conditions described may also be used. The rare gases He, Ne, Ar, Kr and Xe may be mentioned as examples.
It is pointed out, in this connection, that the additional injection of an inert gas does not change the xcex-number. The xcex-number is generally used for describing the air/fuel ratio in combustion operations. The xcex-value is a measure of the ratio of the air quantity introduced into the combustion space to the air quantity required theoretically for complete combustion. Gas turbine burners of the type used in the present invention are operated, as a rule, in a range of 1.8xe2x89xa6xcexxe2x89xa62.2. By mixing an inert gas in with the fuel stream according to the invention, therefore, the xcex-number is not changed, since the inert gas additionally present does not participate in the combustion operation.
The method according to the invention is not restricted only to double-cone burners, but may also be applied to other burners (AEV, premixing burners, diffusion burners).
The method according to the invention may also be employed as a remedy for combustion-driven oscillations due to soft fuel systems. As a result of the additional injection of inert gas, the pressure loss via fuel injection increases. Pressure fluctuations in the fuel system are thereby prevented.
The quantity of inert gas to be injected can be reduced effectively if modulated injection is selected instead of continuous injection. By modulated injection is meant, according to the invention, any injection of inert gas which varies in time. Modulation may take place, according to the invention, at any desired frequency. Preferably, injection is carried out at a frequency of between 0.3 Hz and 5 kHz, the range of 5 Hz to 150 Hz being particularly preferred.
At the same time, within the scope of the present invention, the quantity of inert gas injected per unit time may be varied in any desired way. Preferably, the gas is injected in the form of a pulse of limited time, and subsequently no gas is added for a specific time. If the period of time of gas injection is designated by taddition and the period of time without gas injection by t0, the duration of the modulation of gas injection is obtained as xcfx84=taddition+t0 and the frequency as xcexd=1/xcfx84=1/(taddition+t0)
Within the scope of the present invention, the ratio of taddition to xcfx84 is expressed as a percentage by means of the term xe2x80x9cduty cyclexe2x80x9d. In the case of a duty cycle of 50%, therefore, the period of time of additional gas injection is equal to the period of time in which no additional gas is injected. The addition of a constant quantity of gas corresponds to a duty cycle of 100%.
The injection of additional inert gas into the premix gas ducts of the burner is carried out, according to the invention, with a duty cycle lower than 100%. The range of 1%xe2x89xa6duty cyclexe2x89xa650% is preferred.

Method for minimizing thermoacoustic oscillations in gas turbine combustion chambers


A golf club securing mechanism includes a rigid member and a flexible member. The flexible member is wovenly engaged with the rigid member to define one or more golf club holding regions between the flexible member and the rigid member. The flexible member can be manipulated to vary a size of the one or more golf club holding regions such that in a loose position a golf club can be positioned within one of the golf club holding regions and in a tightened position the golf club is tightly fixed between the rigid member and the flexible member.

As the popularity of golf continues to rise, and as the proliferation of specialty clubs increases, so has golf club theft. It is not uncommon for the average golfer to have in excess of $2,000.00 of clubs in his or her bag. After completing a round of golf, it is common for a golfer to leave the bag unsecured and unattended for long periods of time. This exposes the individual clubs or entire bag with all its contents to easy theft.
Various devices have been designed and implemented to secure clubs to one another, or integrated bag locks that secure the clubs within the bag. No such device is easily portable from bag to bag, or offers security of a variety of bag configurations and club quantities. Nor typically does the locking device provide a means to secure clubs or bag to a permanent rack, or other object.
One such device is disclosed in U.S. Pat. No. 5,004,100, which discusses a device having a plate designed to fit over the open end of a golf bag. The plate has three slots which are closed at one end and open at the other so that a group of clubs can be laterally inserted therein. A U-shaped arm is pivotally attached to the flat plate to close the open end of the slots. The arm can then be locked in place to prevent removal of the clubs.
Such devices are relatively heavy and thereby tend to discourage golfers who prefer to carry their own bag as they play and wish to keep the bag as light as possible. Also, such devices are non-adjustable as to the distance between the slots. Golf bags are sold in a variety of sizes and configurations. A rigid system of locking the clubs restricts the golfer to bags that fit the limitations of the lock. It is likely that a golfer will purchase two or three different bags over the life of his or her clubs and therefore be forced to purchase a new lock with each as the configurations or size change. Further, with the relatively high cost of the device, this makes it impractical.


A control system of at least one flap of a fluid duct of an intake system of an internal combustion engine, including: a swivel axis, at least one flap connected off-center to the swivel axis by which the at least one flap can be swiveled within the fluid duct between positions with different degrees of opening, a swivel lever connected to the swivel axis, the swivel lever pivoting the swivel axis, an elastic working return element connected directly or indirectly to the swivel lever and applying a force to the at least one flap to return the at least one flap toward a home position.

The US 2008/0223025 A1 discloses a passive, exhaust pressure actuated valve assembly for placement inside a tubular exhaust conduit which is pivotally mounted to an off-center axle for rotation between fully closed and fully opened positions. A bias element forces the valve flap toward the fully closed position. The valve flap is shaped in a manner enabling use of the interior surface of the exhaust conduit to define stops at the full closed and full opened positions. The valve flap shape, in conjunction with the bias element arrangement, enables the flap to lie substantially parallel to a longitudinal axis of the conduit in the fully opened position, which provides for minimum back pressure in the conduit. The valve assembly finds particular advantageous use inside the bypass through pipe of a muffler assembly.

Control system of at least one flap of a fluid duct and fluid duct system