The present application is related to and claims priority of prior co-pending Provisional Patent Application No. 60/419,336, filed Oct. 17, 2002 entitled “Latching Off-Chip Hinge Mechanism for Micromechanical Systems (MEMS) Components”. The contents of this provisional patent application are hereby incorporated by reference herein. 


   RIGHTS OF THE GOVERNMENT 
   The invention described herein may be manufactured and used by or for the Government of the United States for all governmental purposes without the payment of any royalty. 
   CROSS REFERENCE TO RELATED PATENT DOCUMENTS 
   The present document is somewhat related to the co pending and commonly assigned patent application documents “OFF SUBSTRATE FLIP-CHIP APPARATUS AND METHOD”, Ser. No. 10/690,158; and “MICROMECHANICAL DEVICE LATCHING”, Ser. No. 10/690,157; that are filed of even date herewith. The contents of these somewhat related applications are hereby incorporated by reference herein. 
   BACKGROUND OF THE INVENTION 
   Commercial semiconductor foundries often limit designers to a few choices of materials or number of structural layers in a fabricated device. As a result it may not be possible to create many specialized devices required for demanding semiconductor or Micro Electro Mechanical Systems (MEMS) applications without custom fabrication methods, methods that are usually expensive to employ. As an alternative, highly complex structures can be made by flip-chip bonding of surface-micromachined features onto a variety of other substrates or even other chips fabricated in the same process. The original often silicon host substrate is then discarded during a following release etch to provide advanced MEMS devices that are suitable for RF, microwave, or optical applications where specific material properties or additional structural layers are required. 
   In recent years, the use of flip-chip assembly to create advanced MEMS devices has been shown to be a fast, reliable, simple and inexpensive method to produce highly planarized devices consisting of as many as five structural layers on virtually any desired substrate. This process has been demonstrated with a variety of micromirror arrays and variable capacitors fabricated atop ceramic substrates to achieve improved RF characteristics. Even more advanced micromirror arrays have been fabricated atop receiving modules prefabricated in a same processing run as the host module. Numerous styles of cantilever, torsion, and piston micromirror arrays have been demonstrated and these boast a variety of desirable characteristics. Mirror devices can for example achieve CMOS compatible low voltage addressing potentials or more than 3 micrometers of stable mechanical deflection since the mirror surfaces can rest as much as 10 micrometers above the substrate. Typical arrays have been designed with as much as 98.8% active surface area. Torsion and cantilever devices have demonstrated as much as 20 degrees of tilt using a variety of flexure arrangements to reduce needed electrical addressing potentials. The mirror surface of each such device is initially fabricated as the underside of a first releasable structural layer such that no topographical effects are induced. As a result, flip-chip micromirrors consistently demonstrate less than 2 nanometers of root-mean square surface roughness. 
   Flip chip bonding of two integrated circuit sized component modules into a MEMS or other single device has however almost universally required each of the component modules to remain on its fabrication substrate or a substitute substrate during the bonding operation. The known few exceptions to this rule involve especially fabricated modules affording some special form of protection for one module. The present invention changes this situation into one wherein someone with access to the most basic device fabrication capability and its tools can achieve flip chip bonded devices, including devices fabricated on two different and incompatible substrate materials and devices fabricated to include multiple MEMS modules in stacked array. Moreover the present invention eliminates a significant difficulty in correctly aligning two substrate-mounted modules for bonding. Since the present invention allows use of simple visual alignment procedures it eliminates the need for an expensive piece of measurement-capable fabrication equipment and need for the skilled user to operate this equipment. In direct terms, the present invention is thus concerned with improved off-substrate bonding. 
   The prior publication and patent art includes numerous examples of hinge and pivot arrangements used for erecting structural elements in an assembled MEMS device or as an active part of the MEMS device function. The concept of using a hinge or pivot as a key part of the assembly or fabrication procedure for a MEMS device, and especially for off chip rotation of substrate-free MEMS modules, appears however to be significantly less well known in the art. Several examples of prior art documents illustrating this state of the MEMS art are included in the references identified with the filing of the present document. 
   It is therefore an object of the present invention to provide a hinge-based arrangement through which simplified flip chip assembly can be accomplished. 
   It is another object of the present invention to provide a rotation based apparatus and procedure by which simplified flip-chip bonding can be accomplished. 
   It is another object of the invention to provide a lockable rotating hinge apparatus and method for assembling MEMS devices. 
   It is another object of the invention to provide a hinge arrangement that is operable by manual manipulation of hinge and associated latching elements. 
   It is another object of the present invention to provide a release, rotate, bond sequence for a flip-chip device. 
   It is another object of the invention to provide a latching hinge arrangement in which pivot pin and hinge clevis or hinge staple portions are achieved in integrated circuit size elements. 
   It is another object of the invention to provide for the non-wired rotation-based combination of incompatible process modules to form an Integrated Microsystem MEMS device. 
   It is another object of the invention to provide for the hinge-based combination of two or more low cost, perhaps incompatible, module fabrication processes to achieve a complex MEMS module. 
   It is another object of the invention to provide for the direct combination of a MEMS module with a CMOS module to form a CMOS MEMS device that is free of module interconnecting wiring. 
   It is another object of the present invention to provide a MEMS module fabrication arrangement in which multiple layers of MEMS elements may be stacked by rotation to form a complex MEMS device. 
   It is another object of the present invention to provide a MEMS device having two, three, four or more MEMS module layers that have been collected in a substrate free rotational alignment sequence. 
   It is another object of the present invention to provide an N layered flip-chip MEMS device. 
   It is another object of the present invention to provide a rotating hinge arrangement inclusive of provisions for convenient initial release of hinged elements from a sacrificial fabrication substrate member. 
   It is another object of the present invention to provide a procedure and apparatus in which all parts included in the upper layers of a hinge inclusive MEMS module are fully releasable during processing. 
   It is another object of the present invention to provide a procedure and apparatus in which a MEMS hinging and latching mechanism can be fabricated using only two uppermost and existing MEMS module layers in its composition. 
   It is another object of the present invention to provide a MEMS rotating hinge arrangement that is capable of large angle rotations. 
   It is another object of the present invention to provide a rotating hinge arrangement inclusive of rigid fixation apparatus for the rotated element. 
   It is another object of the present invention to provide a rotating hinge arrangement subject to fabrication in as few as two structural material layers. 
   It is another object of the present invention to provide a rotating hinge arrangement subject to fabrication in overlapping element form on a sacrificial substrate. 
   It is another object of the present invention to provide a rotating hinge arrangement providing a plurality of protections for a fragile, substrate-free, rotated MEMS module. 
   These and other objects of the invention will become apparent as the description of the representative embodiments proceeds. 
   These and other objects of the invention are achieved by the method of making a MEMS device comprising the steps of: 
   fabricating an array of MEMS modules and an array of MEMS controller modules on first and second fabrication substrate members; 
   a selected one of said array of modules having a sacrificial fabrication substrate member and including a plurality of connecting elements coupling said array of modules with a physically-stiffening header member; 
   each module of said MEMS array including an electromagnetic field-addressable physically movable active member; 
   each module of said MEMS controller array including an electromagnetic field-generating output member; 
   releasing said selected one of said array of modules from said sacrificial fabrication substrate member into a physically-stiffening header member-supported free state; 
   rotating said released selected one of said array of modules into an off substrate attached position of cantilever supporting by said connecting elements from said physically-stiffening header member; 
   aligning and bonding said released rotated array of modules with corresponding unreleased modules of said array of MEMS modules and array of MEMS controller modules to form an array of MEMS devices each having an electromagnetic field-addressable physically movable active member proximate an electromagnetic field-generating output member. 


   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings incorporated in and forming a part of the specification, illustrate several aspects of the present invention and together with the description serve to explain the principles of the invention. In the drawings: 
       FIG. 1  shows the layout of a micromirror module array on a sacrificial fabrication substrate. 
       FIG. 2  shows the  FIG. 1  module array in a hinge-rotated, latched, off-chip state. 
       FIG. 3  shows the layout of an electronic circuit module on which the  FIG. 1  and  FIG. 2  array may be mounted to form a plurality of micromirror MEMS devices. 
       FIG. 4  shows a representative partial cross section view of a representative MEMS device inclusive of modules of the  FIG. 1 ,  FIG. 2  and  FIG. 3  types. 
       FIG. 5   a  shows a more detailed view of one portion of a  FIG. 1  type of MEMS module. 
       FIG. 5   b  shows the  FIG. 5   a  apparatus in a rotated element condition. 
       FIG. 5   c  shows the  FIG. 5   a  apparatus in a rotated and latched element condition. 
       FIG. 6   a  shows a cross sectional view taken along the section line a-a in  FIG. 5   c.    
       FIG. 6   b  shows a cross sectional view taken along the section line b-b in  FIG. 5   c.    
       FIG. 6   c  shows a cross sectional view taken along the section line c-c in  FIG. 5   c.    
       FIG. 6   d  shows a cross sectional view taken along the section line d-d in  FIG. 5   c.    
       FIG. 6   e  shows a cross sectional view taken along the section line e-e in  FIG. 5   c.    
       FIG. 6   f  shows a cross sectional view taken along the section line f-f in  FIG. 5   c.    
       FIG. 6   g  shows a cross sectional view taken along the section line g-g in  FIG. 5   c.    
       FIG. 6   h  shows a cross sectional view taken along the section line h-h in  FIG. 5   c.    
       FIG. 6   i  shows a cross sectional view taken along the section line i-i in  FIG. 5   c.    
       FIG. 6   j  shows a cross sectional view taken along the section line j-j in  FIG. 5   c.    
       FIG. 6   k  shows a cross sectional view taken along the section line k-k in  FIG. 5   c.    
       FIG. 7  shows details of a typical hinge mechanism usable with the present invention. 
       FIG. 8  shows a first part of another use of latch concepts in the present invention. 
       FIG. 9  shows a second part of another use of latch concepts in the present invention. 
       FIG. 10  shows a completed MEMS device view of the  FIG. 8  and  FIG. 9  latch concepts. 
       FIG. 11  shows a MEMS module alignment result achieved with the present invention. 
   


   DETAILED DESCRIPTION OF THE INVENTION 
   The latching off-chip arrangement of the present invention enables the prerelease of for example MEMS modules into a state that is accessible and convenient for ensuing processing such as bonding with for example an electronic circuit module to form a flip-chip MEMS device. It appears especially desirable that the MEMS module in the present invention is free of its fabrication substrate and yet sufficiently well supported and protected to be of convenient access and manipulation capability during bonding and possibly other steps of the MEMS device fabrication sequence.  FIG. 1 ,  FIG. 2 ,  FIG. 3  and  FIG. 4  in the drawings illustrate the use of this latching off-chip hinge mechanism in a preliminary overall manner. In  FIG. 1 ,  FIG. 2  and  FIG. 3  a flip-chip MEMS array is rotated and latched off the edge of a host module, i.e., off a sacrificial substrate used to fabricate the MEMS module portion of the MEMS device. As may be apparent to those skilled in the MEMS art it is also possible to reverse the roles of the MEMS module array and the electronic circuit module array in this  FIG. 1 ,  FIG. 2 ,  FIG. 3  and  FIG. 4  rotation based sequence with suitable modifications of the arrays. A detailed description of the  FIG. 1  and  FIG. 2  mechanism and its fabrication, assuming selection of a provided optional MEMS module rotation option, follows the present overall introductory discussion. 
   The micromirror array  100  shown in  FIG. 1  is arranged to include an 8×8 modules array of cantilever micromirror modules intended for marriage with similarly sized and compatibly disposed electronic circuit modules that may also be in array form. The present invention is of course also applicable to individual devices that are not disposed in this array form. In  FIG. 1  the micromirror array  100  is attached to a hinge mechanism  102  through tethers  104  that can be severed once the array is rotated and bonded onto for example a CMOS receiving module array as is shown at  300  in  FIG. 3 . The tethers  104  may be of whatever length is needed in order to allow positioning of a MEMS module over the electronic circuit module i.e., tether  104  length is determined by the size and layout of the electronic circuit module and the need to reach across parts of this module in positioning and aligning the MEMS module. 
   After release, the array  100  is rotated off the edge of the chip  106  and latched into place by a slider assembly shown generally at  108  in the  FIG. 1  drawing. An etch plate, or release plate or protective member or shield member or header member  112  (herein primarily referred-to as an etch plate member) is used to connect the tethers  104  to the hinge mechanism  102  and serves the significant additional functions described subsequently herein. The name “etch plate” is recognized as being somewhat generic and non descriptive at first blush for the element  112 , however since one of the functions of this element is to supply structural support for a MEMS device during susceptible parts of an etching process this name is believed not altogether inappropriate. The hinge mechanism  102  is anchored to the substrate  110  of the chip  106  by a row of first hinge portions. A row of second hinge portions connects the etch plate or protective member or header members  112  to the row of first hinge portions and the substrate  110  via a hinge pin, all as described in greater detail below herein. 
   Notably in the  FIG. 2  status the array  100  can be metallized with reflective materials without masking or preprocessing. The array  100  is then aligned over the CMOS receiving module  300  of  FIG. 3  where bonding, using for example one of a variety of conductive adhesive materials, may be accomplished. It is particularly notable that the procedure represented in  FIG. 1 ,  FIG. 2  and  FIG. 3  can be completed using only a standard probe station probe element as a manipulating tool. In the identified example the final MEMS devices will consist of surface-micromachined mirror surfaces that are bonded directly above address electrodes located over, in this instance, latching CMOS addressing circuits. Each mirror surface may be supported by compliant flexures connected to a bonding frame that surrounds it. This frame also provides uniform resting support throughout the array. 
   Additionally in order to better appreciate details of the present invention  FIG. 4  in the drawings illustrates a single MEMS device achievable with the assistance of the invention in which a mirror surface deflects when a CMOS address cell is activated. In the  FIG. 4  cross sectional view an individual cantilever micromirror  400  and  400 ′ (in its two operational positions) of a MEMS module  402  is disposed positions enabling its control by the electrical circuits of a CMOS module  404 . In the  FIG. 4  illustration, the address electrode  406  of the CMOS module  404  is shown wired to the drain of some arbitrary complementary logic circuit transistor to effect this control. The electrode  406  is formed in the upper metal layer of a CMOS process and remains covered with a thin layer of oxide  408  for protection and isolation from the mirror surface. Each feature within a  FIG. 4  type of device is carefully arranged with specific topographical considerations such that mating elements align properly when positioned into the  FIG. 4  condition and no object interferes with the motion of any other. 
   In  FIG. 4  the mirror  400  lower surface will actually come to rest on an area of field oxide at  412 . Without the spacer layers shown under each column of the bonding frame, at  410  for example, some of the mirror  400  surfaces in an array would achieve no more than a 2 degree range of tilt. The spacer layers  410  added to the MEMS module however elevate the mirror  400  enough for many devices to achieve roughly 5 degrees of tilt. The pivot point for the mirror  400  is located on the spacer layers  410  portion of the MEMS module  402  and appears at  412  in  FIG. 4 . The  FIG. 4  drawing illustrates the final disposition of the modules  402  and  404  in a MEMS device preferably following use of the present invention in achieving this disposition. The present invention is of course not limited to micromirror devices as shown in  FIG. 4  but can relate to most MEMS device types. 
     FIG. 5  in the drawings includes the vertically aligned views of  FIG. 5   a ,  FIG. 5   b  and  FIG. 5   c  and shows details previously recited and additional details relevant to the present invention. Identification numbers appearing in the  FIG. 5  drawings and the other drawings herein repeat those used in  FIG. 1  through  FIG. 4  to the best degree possible; in other words element identification numbers remain consistent in the drawings of the present document once assigned, to the best degree possible. New identification numbers including the drawing figure number in the hundreds digit position are assigned in  FIG. 5  and the ensuing drawings as are needed in the related discussion. 
   The array  100  and the  FIG. 5  mechanism may be fabricated from a variety of materials including semiconductor materials. Notably the materials used in the array  100  and the  FIG. 5  mechanism may be either similar to or totally different from and incompatible-with the materials used in the electronic circuit module  300  or  404  with which the array  100  and the  FIG. 5  mechanism are to be married in a completed MEMS device. This is of course one of the major advantages of a MEMS device. One family of materials that are convenient for realization of at least experimental or prototype MEMS modules is based on the Multi-User MEMS Process (MUMPS) that is available from Cronos Incorporated, www.memsrus.com. Cronos Incorporated was acquired by MEMSCAP in November, 2002, see http://www.memscap.com/. The MUMPS process is especially relevant to MEMS device fabrication in a so-called semiconductor foundry setting where a significant volume of and variety of semiconductor devices of individual customer origin are fabricated on a commercial basis. Fundamentally the MUMPS process involves the use of Silicon semiconductor materials and provides two releasable, user-configured, layers of poly-crystalline doped and electrically conductive silicon structural material, herein these layers are identified as “Poly-1” and “Poly-2”. These layers are first and second deposited layers over a substrate or substrate-carried structures, layers that are segregated by an intervening layer of easily etched and removed oxide material such as silicon dioxide. A substrate attached “Poly-0” layer is also present in the MUMPS process however this layer is not used in the flip process described herein. Use of the MUMPS process and these materials is presumed in following portions of this document. The trapped MUMPS process oxide layer is preferably of 0.5 micrometer thickness in the present invention. Notwithstanding this MUMPS process presumption, it is of course realized that MEMS devices can be fabricated from a large variety of materials including, for example Gallium Arsenide, Germanium and other semiconductor materials, and therefore applicant desires not to be limited by this disclosure in terms of the MUMPS and Silicon materials process. 
   The MUMPS process and its two oxide-separated polysilicon layers is in reality a desirably simple and inexpensive process in comparison with for example the SUMIT process which provides up to four releasable layers of semiconductor material. The SUMIT process is known by the more complete name of Sandia Ultraplanar Multi-level MEMS Technology and is available from Sandia National Laboratories at Kirtland Air Force Base in Albuquerque, N. Mex., http://mems.Sandia.gov/scripts/index.asp. Either the SUMIT or the MUMPS process or another process of these natures as is known in the art may be used with the present invention. It is especially notable that even a relatively simple and two layer process such as MUMPS may be enhanced significantly by way of the present invention since the invention easily supports an arrangement wherein multiple MEMS modules are fabricated on the same or on different substrates and are then stacked on top of each other during the bonding process of a MEMS device. In this manner the present invention enables the fabrication of a complex MEMS device of 2, 4, 6, 8 or more layers or even any number, N, layers while using merely a simple and inexpensive, even two layered, fabrication process. The complexity of the fabricated MEMS device can be enhanced significantly by this access to a greater number of releasable layers during fabrication. 
   In  FIG. 5   a  the etch plate  112 , and its associated collection of hinge portions  500 ,  502  and  504  etc. of hinge  512 , rigidly support the tethers  104 . In the arrangement of the present invention these tethers  104  connect with a flip-chip device to be rotated off the edge  506  of the host chip or sacrificial substrate  110  on which the  FIG. 5   a  MEMS module is fabricated. Although hinges for use in MEMS and other surface micromachined devices are believed known in the art, a brief discussion of the  FIG. 5  hinge  512  is believed appropriate herein. Thus, each of the hinge portions  500 ,  502  and  504  appearing in the  FIG. 5  drawings represents a clevis element of an actual pin and clevis hinge of the type shown in greater detail in the  FIG. 7  drawing herein. In  FIG. 5  these clevis element are represented to be attached to the etch plate  112  while the pin elements of each these hinge portions are attached to or integral with the substrate  110 . 
   In the  FIG. 7  drawing the clevis element of a hinge appears at  702  and a contoured form of a pin element appears at  700 . The wings  704  and  706  in the  FIG. 7  hinge attach the clevis element to a substrate member while the pin element  700  attaches to a hinge-anchored rotating element. Thus the  FIG. 7  hinge is a reverse arrangement of the hinge portions appearing in the  FIG. 5  drawing. A hinge of similar arrangement to that of the  FIG. 5  and  FIG. 7  hinge is additionally disclosed in the U.S. Pat. No. 5,994,159 of V. A. Aksyuk et al. and also in the U.S. Pat. No. 6,300,156 of H. L. Decker et al.; patents that are hereby incorporated by reference herein. Notably the Aksyuk et al. and the Decker et al. patents involve the erection of pseudo three dimensional structures on the surface of a MEMS device rather than the rotated, sacrificial substrate-free, processing of a MEMS module. 
   In actually each of the hinge elements appearing in the  FIG. 5  and the  FIG. 7  drawings is comprised of polysilicon in a MUMPS process device. According to this arrangement each of the clevis and wings  702 ,  704 ,  706  are portions fashioned by etching from a single upper layer of polysilicon, i.e., a Poly-2 layer while the pin element  700  is part of a lowermost and first deposited lower Poly-1 layer of polysilicon. These two layers of polysilicon are originally separated by an etch-responsive layer of oxide material that initially fills the interior of the clevis  702  between polysilicon layers until it is removed in a controlled etching sequence to free the pin  700  into the illustrated rotatable condition. During fabrication of the polysilicon layers once the polysilicon 1 hinge pin  700  is formed the oxide layer and the overlying polysilicon 2 layer conform to its shape and thus form the shape of the clevis  702 . Notably the uppermost or Poly-2 of the two polysilicon layers is not required to completely surround the pin element  700  in order to achieve the  FIG. 7  hinge; the lower portion of the clevis  702  is in reality supplied by the substrate of the device. The two polysilicon layers of the MUMPS process are in actually also sufficient to form each of the other MEMS module elements shown in the  FIG. 5  drawing as is noted in appropriate locations of the following paragraphs of description. 
   The etch plate  112  is fabricated with initial tether connections to the anchor member  516  shown in  FIG. 5   a  and  FIG. 5   c . According to this arrangement the etch plate remains captured in its connection with the substrate  110  notwithstanding removal of the oxide layer (or layers) that originally hold it captive, i.e., oxide layers removed during the course of normal fabrication of the MEMS module. As this statement implies, the present invention can be fabricated in structural layers of a device that are elsewhere needed; the addition of layers for present invention purposes is thus not necessary. 
   Tethered release of the etch plate into a rotatable condition in the  FIG. 5  apparatus is therefore a fully controllable event that may be initiated at a convenient point in the fabrication process following the oxide etching event, a point in fact preferably selected to be late in the processing and after release of the array  100 . Remainder portions of the tether elements used to accomplish this retention and release of etch plate  112  from substrate anchor element  516  appear at both  518  and  520  in the  FIG. 5   c  drawing. These remaining portions are joined in the  FIG. 5   a  pre-rotation condition of the MEMS device and are severed by a burn-through electrical current or physical rupture or by laser burning in the manner of the tethers  104  as described elsewhere herein. In the  FIG. 5   a  pre release condition the joined tethers at  518  and  520  oppose the uplifting force of the lifting beams  508  and  510 . Notably processing of the  FIG. 5  modules can be accomplished by way of conventional non-rotating flip-chip processing techniques by omitting the severing of tethers  518  and  520  and thus maintaining the MEMS module in the  FIG. 5   a  condition if desired. Cross sectional details of the substrate anchor element connecting with tethers  104  are shown in the  FIG. 6   a  drawing. 
   The cooperating action of the tethers  518 ,  520  and anchor  516  in holding the etch plate  112  in its substrate adjacent  FIG. 5   a  condition until intentionally terminated by a burn or laser releasing event thus allows the  FIG. 5  apparatus to electively be used in either the hinge-rotated or the conventional non-hinge-rotated bonding modes. If the tethers  518 ,  520  are maintained in integral condition the  FIG. 5  MEMS module may be bonded in the conventional substrate present flip-chip manner since the combination of hinge  512  and anchored tethers immobilize the MEMS module  100  with respect to the substrate. If however these tethers are segregated and hinge rotation of the etch plate and MEMS module are thusly allowed to occur, then the presently discussed off chip bonding mode becomes available. 
   Also appearing in the  FIG. 5   a  and  FIG. 5   c  drawings are a pair of lifting beam members  508  and  510  used in accomplishing an initial separation of the etch plate  112  and the array  100  from the substrate  110  in commencement of the  FIG. 5   b  and  FIG. 5   c  illustrated off chip rotation process after segregation of tethers  104 . The lifting beams  508  and  510  may be simply passive bimorph actuators, fabricated from polysilicon and overlying gold for example, that are used to initially elevate the arrays as a result of temperature-induced thermal stresses generated in the lifting beams following environmental temperature change (e.g. change from fabrication temperature to room temperature). This thermal mismatch between the two layers of each beam  508  and  510  results in an upward force at the rightmost end of the beams  508  and  510  once the module elements are released from the substrate by an oxide etching process; the presence of this lifting force therefore precedes segregation of the tethers at  518  and  520 . 
   The free ends of the lifting beams  508  and  510  are placed near the rotational axis of the hinges  512  in order to maximize the lifting effect on the etch plate  112  and so that the flip-chip structures are sufficiently elevated for convenient access. Preferably this lifting is arrange to permit use of probe tip engagement with etch plate  112  in completing the rotation. Separation distances in the range of 10 to 15 micrometers between the hinge axis and the hinge-adjacent ends of the lifting beams  508  and  510  are found to be suitable. Cross sectional details of the free end of the lifting beams  508  and  510  appear in the  FIG. 6   k  drawing. For stability enhancement purposes the etch plate  112  is arranged to be larger than the largest flip-chip structure to be serviced. The etch plate is preferably the last element on the surface of the host module to be released and therefore the only structure to bear the force of the lifting beams  508  and  510 . Otherwise, delicate features such as micromirror flexures could rupture before the surface is fully released from the sacrificial substrate. The etch plate  112  is preferably composed of a multi layered structure of polysilicon as is illustrated in the  FIG. 6   i  drawing. 
   The thin tethers used in locations  518  and  520  in the  FIG. 5  modules may be removed by a laser cutter or burned off when an electrical potential is applied between for example the anchor and the small pad adjacent to it. The tethers  104  connecting the etch plate to the flip-chip structure are intended to be removed in the same manner once chip rotation and bonding are complete. A small divot or necked-down region in the end of the tethers can concentrate either the mechanical stress or the electrical current density of a burn-through current at a selected point along the edge of the flip-chip structures. A laser cutter is also quite effective for tether disconnection and is in fact the preferred method of removing all forms of tethers from the  FIG. 5  mechanism. The anchor tethers  518 ,  520  are cut to facilitate off-chip hinge bonding while the flip-chip tethers at  104  are severed to permit use of a flip-chip bonding machine and thermo-compression bonding in assembling the modules into an integral flip-chip device. 
   The etch plate  112  is in fact a MEMS module protecting element of some perhaps surprising significance in the overall scheme of the present invention. It is in fact the stabilizing and rigidizing effect of this etch plate member on the flip-chip MEMS module  100  that enables successful manipulation and handling of the module in the espoused removed-substrate state. Without the presence of this etch plate  112  the substrate-removed module  100  would in fact be so fragile and damage susceptible as to be of little or no practical value. Such a substrate-removed module would be vulnerable to distortion and breakage in air currents or washing baths and during manual manipulation for bonding attempts, especially since it is not only thin and fragile in its own right but receives only limited support and contour control by way of elongated severable tethers of for example polysilicon material. 
   According to the present invention the flip-chip MEMS module  100  is in fact effectively no longer rotatable in the  FIG. 5   c  drawing view but is rigidly held in position with respect to substrate  110  by the combined effect of the hinge  512  and the latching slider assembly  105  and its engagement with the etch plate  112  in  FIG. 5   c . This engagement involves the etch plate tongue element  514  as is discussed in subsequent paragraphs below. By way of clarifying summarization therefore, in the  FIG. 5   c  view of the MEMS module the etch plate  112  has been rotated through an angle of substantially one hundred eighty degrees from the  FIG. 5   a  fabrication position, rotated into a tether supported off chip posture, by way of the hinge  512 . The etch plate and thus the MEMS module are held rigidly in this position by the freedom of rotation-only characteristic of the hinge  512  together with the rotation-precluding nature of the latching slider assembly  105 . 
   The latching slider assembly  105  is shown in plan view detail in the  FIG. 5   b  and  FIG. 5   c  drawings. Cross sectional views taken along the slider assembly  105  and through adjacent portions of the  FIG. 5  assembly, views taken along the eleven cutting lines a-a through k-k in  FIG. 5   c , appear in the eleven views of the  FIG. 6  drawing herein and are described in ensuing paragraphs herein. As may be observed with respect to the differences between the slider assembly  105  as it appears in the  FIG. 5   b  and  FIG. 5   c  drawings the leftmost triangular shaped portion  524  of the slider assembly  105  in  FIG. 5   b  becomes segregated into two portions in the  FIG. 5   c  drawing—as a part of the cap portion  522  of the slider assembly being mating with the tongue portion  514  of the etch plate element  112 . This mating may in fact be preferably accomplished by way of a probe tip,  528  in  FIG. 5   c , engaging the aperture  530  in the slider pentagonal portion  524  with a rightward directed force to close the slider assembly gap at  536 , in  FIG. 5   b.    
   The  FIG. 5   b  gap  536  preferably is made of a shorter length than the tongue  514  in order to prevent damage to the tongue  514  and the etch plate  112  from inadvertent excessive rightward movement from the probe tip  528  engagement. According to this arrangement the two slider portions meet at  540  in  FIG. 5   b  before damage to the tongue  514  can occur. Lengths of 45 micrometers and 50 micrometers for the gap  536  and the tongue  514  are found to be satisfactory for this damage limiting purpose. The remainder parts  532  and  534  of the pentagonal shaped slider portion  524  are actually substrate-attached guide rails serving both to hold the slider assembly in a captive substrate-parallel condition and to prevent inadvertent movement of the slider assembly  105  in the leftward direction by the probe tip  528 . The cross sectional shape of the remainder parts  532  and  534  are shown in the drawing of  FIG. 6   b  where the sliding but capturing nature of the remainder parts  532  and  534  also appears. The  FIG. 5   b  and  FIG. 5   c  thin rectangular patterns at  538  in the slider assembly represent dimples resulting from formation of elongated sliding feet  537  as are more visible in the  FIG. 6   d  drawing. The space immediately below the feet  537  in  FIG. 6   d  is of about one-half micrometer thickness and is preserved during the deposition process by the presence of a later removed oxide layer. 
   The latching slider assembly  105  in  FIG. 5  is thus topographically disposed using a vertical spacer plate to elevate the tongue and cap during fabrication. Once rotated, the tongue portion  514  of the etch plate  112  rests beneath the cap  522  of the slider assembly  105  so that the tongue and cap mate when the slider assembly  105  is in the engaged-with-etch-plate position. The tongue portion  514  is formed in the upper or Poly-2 polysilicon layer of the  FIG. 5  device; when rotated into the  FIG. 5   b  and  FIG. 5   c  positions this upper layer tongue thus is disposed in the lower layer of the rotated etch plate  112  where it is engaged by the slider assembly cap  522 . The slider assembly is arranged with left end and right end stops in  FIG. 5  to retard excessive, perhaps manually achieved, motion that may damage the rotated etch plate. 
   After performing a release etch, the etch plate  112  may be rotated and latched into position using the standard micromanipulator of a probe station or even by a hand-held probe tip, as represented at  528  in  FIG. 5   c , with some practice. When thusly rotated the flip-chip structures formed in the MEMS modules ( 402  in  FIG. 4 ) are then ready for bonding to for example CMOS receiving modules ( 404  in  FIG. 4 ) using solder, indium or a variety of conductive adhesives.  FIG. 5   c  shows the slider assembly and etch plate in the latched position and illustrates an additional pad  542  connecting with the tongue  514  that may be used to receive probe tip force and thus accomplish a leveling of the rotated etch plate  112  before the slider assembly can be engaged with the tongue in some instances. 
   With the  FIG. 5  anchor tethers cut, the lifting beams  508  and  510  provide sufficient elevation such that arrays may be easily rotated off the edge of the module in the presence of methanol fluid resistance during a release rinse. Care is however needed when removing the substrate free MEMS module structure from a rinse bath to avoid surface tension damage to delicate elements. After removal from the rinse the arrays can then simply be dried in air rather than using a critical point dryer since they no longer rest above a substrate that would ordinarily damage mirror surfaces or other structure as methanol or another rinse agent evaporates. The lifting beams  508  and  510  appear in cross sectional representation in the FIG.  6   a  drawing where a metallic gold layer is shown at  600 ,  602  and  604  and this gold is shown to overlay a Poly-1 layer. 
     FIG. 6  in the drawings therefore includes the eleven views of  FIG. 6   a ,  FIG. 6   b ,  FIG. 6   c ,  FIG. 6   d ,  FIG. 6   e ,  FIG. 6   f ,  FIG. 6   g ,  FIG. 6   h ,  FIG. 6   i ,  FIG. 6   j  and  FIG. 6   k . Each of these  FIG. 6  drawings is a cross sectional representation of a part of the  FIG. 5   c  MEMS module that is taken along the section lines identified with the same lower case letters in the  FIG. 5   c  drawing. Element identification numbers used in the  FIG. 5   c  drawing and in the other drawings of this document are repeated to the best degree possible in the  FIG. 6  drawings and are believed to thus identify the structure shown in the  FIG. 6  drawings to a degree needing only brief additional clarifying comments. 
   By way of such clarification, the  FIG. 6   a  drawing shows the substrate of the  FIG. 5  devices at  606 ; this substrate may be made of doped silicon in the MUMPS process devices. Overlaying the substrate  606  is a nitride electrical insulation layer  608  that may be of ½ to 5 micrometers thickness for example. The upper surface of the nitride layer  608  may be referred-to as the “fabrication surface” of the  FIG. 6  device. At  516  in the  FIG. 5  and  FIG. 6  drawings is represented the anchor used to hold the etch plate  112  in its pre release condition until the tether-severing release is elected. The anchor  516  is composed of rigidly joined Poly-1, Poly-2 and metal layers. 
   The  FIG. 6   b  drawing represents a cross sectional view taken along the section lines b-b in  FIG. 5 , i.e., through the head  531  portion of the slider assembly  105 . In  FIG. 6   b  the slider head guide rails  532  and  534  may be appreciated to hold the Poly-1 layer  607  of the head  531  captive notwithstanding its movement to the right in the  FIG. 5   c  drawing. The leftwise motion stop portions of the slider head guide rails  532  and  534  may also be appreciated from the  FIG. 5   c  drawing. The nature of the continuous vias  523  and  525  surrounding the periphery of the head  531  and also surrounding the pentagonal opening  530  in the center of the head  531  may also be appreciated from the  FIG. 6   b  drawing. Beneath these vias  523  and  525  lies a permanent joining of the Poly-1 and Poly-2 layers of the slider head at  605  and a trapped oxide space  609  remaining between the Poly-1 and Poly-2 layers as a result of being completely surrounded by the vias  523  and  525  even during an etching step preceding the  FIG. 6   b  view. This trapped oxide transforms the  FIG. 6   b  elements into a three-layer structure of significant rigidity and desirable stiffness. The permanent joining of the Poly-1 and Poly-2 layers of the slider head at  605  in  FIG. 6   b  may of course be achieved by way of forming removed areas in the oxide layer separating the Poly-1 and Poly-2 materials prior to deposition of the Poly-2 layer. 
   The  FIG. 6   c  drawing represents a cross sectional view taken along the section lines c-c in  FIG. 5 , i.e., through the leading portion of the head  531  and the adjoining portion of the slider assembly  105 . The dimples at  527  in both the  FIG. 5   c  and  FIG. 6   c  views of the slider assembly  105  are of interest in the  FIG. 6   c  drawing. These dimples result from a formation of the sliding feet  605 . The two-micrometer thick oxide layer formerly present at  607  in  FIG. 6   c  is etched into a recessed pattern of about ½ micrometer thickness below the feet  605  in order to form the feet. Other features of the  FIG. 6   c  drawing are identified in connection with the  FIG. 6   b  drawing. This ½ micrometer thickness provides movement clearance for the slider assembly  105  during the flipped-over MEMS module latching event. 
   The  FIG. 6   d  drawing represents a cross sectional view taken along the section lines d-d in  FIG. 5 , i.e., through a single Poly-1 layer portion of the slider assembly  105 . The nature of the  FIG. 5  recesses  538  overlying the feet at  537  in  FIG. 6   d  is visible in the  FIG. 6   d  drawing.  FIG. 6   d  is a suitable location in the  FIG. 6  drawings to also appreciate that the slider assembly  105  in the  FIG. 5  drawing is in fact composed of a single elongated strip of the Poly-1 material, material appearing at  543  in the  FIG. 6   d  drawing, and that this single strip of Poly-1 is overlaid at its right most and left most ends in  FIG. 5  with segments of Poly-2 material forming the head and sliding cap portions of the  FIG. 5  assembly. 
   The  FIG. 6   e  drawing represents a cross sectional view taken along the section lines e-e in  FIG. 5 , i.e., through an intermediate portion of the slider assembly  105 . Several somewhat unusual details of the  FIG. 5  assembly appear in the  FIG. 6  drawing; one of these details concerns the manner in which the sliding cap  522  and also the slider assembly  105  are held in captivity adjacent the substrate  606 . This captivity is achieved by way of the guide rails at  540  in both  FIG. 5  and  FIG. 6   e  holding the Poly-1 layer portions at  611  in confinement below the guide rails. The Poly-1 layer portions at  611  are joined to the cap  522  at  610  in  FIG. 6   e  in the joined polysilicon layers manner discussed with respect to the connection  605  in  FIG. 6   b  and thus the two layer portions at  611  and the cap  522  form a single entity that is confined in sliding fashion by the guide rails  540 . Immediately below the cap  522  in the  FIG. 6   e  drawing is a dummy plate member  614  of Poly-1 material used to provide spacing during fabrication of the cap  522  for the tongue  514  that is ultimately held in captivity by the cap  522 . The dummy plate member  614  is in a coplanar relationship with tongue  514  when the etch plate  512  is in the latched condition. The square dots  519  in the guide rails  540  in  FIG. 5  represent anchor points by which the guide rails  540  and an intermediate layer of Poly-1 material are attached to the nitride layer  608  and the substrate  606  as is shown at the two locations  519  in the  FIG. 6   e  drawing. The similar appearing but smaller square dots at  521  in the  FIG. 5   b  drawing represent connecting vias between Poly-1 and Poly-2 layers as appear at  521  in the  FIG. 6   e  drawing. 
   The  FIG. 6   f  drawing represents a cross sectional view taken along the section lines f-f in  FIG. 5 , i.e., through another portion of the slider assembly  105 . The only significant difference between the  FIG. 6   e  drawing and the  FIG. 6   f  drawing lies in the absence of showing the guide rail substrate connections at  519  in  FIG. 6   e  in the  FIG. 6   f  drawing. 
   The  FIG. 6   g  drawing represents a cross sectional view taken along the section lines g-g in  FIG. 5 , i.e., through another portion of the slider assembly  105  as it is engaged with the tongue  514 . Presence of this engaged tongue  514  rather than the dummy plate  614  represents the major difference in  FIG. 6   g  from that shown in  FIG. 6   f . Note also the absence of the guide rails  540  in the  FIG. 6   g  drawing; this absence occurs because the  FIG. 6   g  view actually is taken from a flipped location off the substrate  606 . 
   The  FIG. 6   h  drawing represents a cross sectional view taken along the section lines h-h in  FIG. 5 , i.e., through another off substrate portion of the flipped MEMS module assembly. Although little effort is made to maintain scale consistency either within the  FIG. 5  and the  FIG. 6  drawings or between the  FIG. 5  and  FIG. 6  drawings, the  FIG. 6   h  drawing is the first in which scale inconsistency becomes immediately apparent. This scale difference is notable with respect to the size of the flipped pad  542  in the  FIG. 6   h  drawing and the layer of Poly-1 material at  543  in the  FIG. 6   d  drawing; these two areas are in fact of the same physical size and are moreover of the same physical size as the void area  503  appearing in the  FIG. 5   b  drawing where the pad  542  was actually formed during the process of fabricating the  FIG. 5  MEMS module. As shown in the  FIG. 6   h  drawing the pad  542  is composed of an interconnected combination of Poly-1 and Poly-2 layers. As noted above herein the pad  542  provides a convenient area to which probe tip pressure may be applied in order to flatten parts of the  FIG. 5  module especially during engagement of slider cap  522  with tongue  514 . The void area  503  is hidden by the slider head  531  in the  FIG. 5   c  drawing. Another void area appears at  544  in the etch plated  112  in the  FIG. 5   c  drawing; this void area is of course the location in which the slider head  531  was fabricated; slider head and void area  544  are coincident in the pre-rotation view of  FIG. 5   a.    
   The  FIG. 6   i  drawing represents a cross sectional view taken along the section lines i-i in  FIG. 5 , i.e., through a third off substrate portion of the flipped MEMS module assembly. The notable new feature in the  FIG. 6   i  drawing is the metallic pad  620 ; this metallic pad also appears in the  FIG. 5   a  drawing where its intended purpose is suggested by proximity to the anchor  516 . By way of the pad  620  and the metallic pad portion of the anchor  516 , at  602  in the  FIG. 6   a  drawing, it is possible to lower two probes onto the  FIG. 5  module and pass an electrical current between these two pads in order to burn through the tethers shown in remainder fashion at  518  and  520  in the  FIG. 5  drawing. 
   The  FIG. 6   j  drawing represents a cross sectional view taken along the section lines j-j in  FIG. 5 , i.e., through a fourth off substrate portion of the etch plate  112  of the flipped MEMS module assembly. In the  FIG. 6   j  drawing the void nature of the pentagonal pattern surrounding the tether remainder portions at  520  is clearly visible at  622 . This pentagonal void arises of course from the slider head  531  having been fabricated in this location in the  FIG. 5   a  view and previous conditions of the MEMS module apparatus. The separated but connected two polysilicon layer composition of the etch plate  112  is also apparent in the  FIG. 6   j  drawing. The often trapezoidal cross section nature of the tethers  104  connecting the etch plate  112  with the MEMS module  100  is also apparent in the extreme left and right portions of the  FIG. 6   j  drawing. 
   The  FIG. 6   k  drawing represents a cross sectional view taken along the section lines k-k in  FIG. 5 , i.e., through the movable head or etch plate  112  engaging portion of the lifting beam  510  in the flipped MEMS module assembly. By comparing the  FIG. 6   k  drawing with the  FIG. 6   a  drawing it is possible to see that the head portion of the lifting beams is composed of only polysilicon material without the presence of the metallic layer. 
     FIG. 8  through  FIG. 11  in the drawings show another MEMS device use of the latch arrangement described in the  FIG. 5  and  FIG. 6  drawings. In the  FIG. 8  drawing there appears a flexibly connected electrical interconnection bond pad that is a part of a MEMS module for a MEMS device, i.e., a sacrificial substrate micromechanical module as this module appears following removal of the sacrificial substrate. The  FIG. 8  bond pad  800  is provided with two tongue elements  802  and  804  that are similar in nature to the tongue element  514  appearing in  FIG. 5  herein. The  FIG. 8  tongue elements however accomplish a different and permanent function in the MEMS device in that they hold the bond pad  800  in a continuing electrical connection with a corresponding pad  900  of a MEMS receiving module such as the module of  FIG. 9  herein. 
   As may be anticipated by the presence of the latch elements  902  and  904  in the  FIG. 9  drawing, the  FIG. 8  bond pad  800  is intended for latched mating with the  FIG. 9  bond pad  900  during assembly of the  FIG. 8  and  FIG. 9  modules into a MEMS device. This latched mating may also be accomplished with the use of manually manipulated probe tips after alignment of the  FIG. 8  and  FIG. 9  modules. During the latching part of this sequence one probe tip may be used to hold the aligned modules and pads in pressure fixed position and another probe tip engaged sequentially with each of the sliding caps of latches  902  and  904  to lock the tongues  802  and  804  into a permanent position. In this permanent position the bonding pads  800  and  900  are held in intimate surface contact to complete the desired electrical interconnection between modules. A series of bonding pads of the  800  and  900  types may be dispersed around the periphery of the  FIG. 8  and  FIG. 9  modules; orientation of the tongues and latches for these pads may of course be altered from that shown in  FIG. 8  and  FIG. 9  to allow closer spacing of adjacent pad pairs when needed.  FIG. 10  in the drawings shows an enlarged view of two bonding pads of the  800  and  900  types in their mated condition with the included sliding latch being in the locked or closed condition. 
     FIG. 11  in the drawings shows a view somewhat like that of  FIG. 10  of two flip-chip pads in the aligned and bonded condition. The  FIG. 11  drawing is included herein for the purpose of illustrating the accuracy achievable during a flip-chip bonding operation using the rotated and latched off chip alignment and bonding of the present invention. In the  FIG. 11  drawing, a drawing originating in a microphotograph of an actual bonded MEMS module pair, each of the small tooth-like serrations  1100  surrounding the illustrated bonded flip-chip pads is of two micrometers width and two micrometers length in its physical dimensions. With details of these dimensions being shown in the  FIG. 11  drawing it is clear that a misalignment between the superimposed pads of  FIG. 9  and  FIG. 10  would be clearly visible if it measured so much as one quarter or one half of a micrometer in dimension. As represented in  FIG. 11  however achievement of alignments well within this tolerance is achievable with use of the alignment enabled by the present invention. 
   The foregoing description of the preferred embodiment has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Obvious modifications or variations are possible in light of the above teachings. The embodiment was chosen and described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the inventions in various embodiments and with various modifications as are suited to the particular scope of the invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally and equitably entitled.
A locked hinge based technique for controllably holding surface-micromachined modules off the edge of a substrate for subsequent processing. The mechanism enables reliable, accurate, and low-cost fabrication of even complex multi layer flip-chip MEMS devices using for example only a simple two-layer module processing sequence, a sequence involving materials already in use in the process. The sequence is also free from the interference of an alignment-hindering sacrificial substrate member. The technique is disclosed by way of a micromirror example and is arranged for convenient bypassing where use of another bonding technique is desired.