Abstract:
A bonded substrate comprising two semiconductor substrates is provided. Each semiconductor substrate includes semiconductor devices. At least one through substrate via is provided between the two semiconductor substrates to provide a signal path therebetween. The bottom sides of the two semiconductor substrate are bonded by at least one bonding material layer that contains a cooling mechanism. In one embodiment, the cooling mechanism is a cooling channel through which a cooling fluid flows to cool the bonded semiconductor substrate during the operation of the semiconductor devices in the bonded substrate. In another embodiment, the cooling mechanism is a conductive cooling fin with two end portions and a contiguous path therebetween. The cooling fin is connected to heat sinks to cool the bonded semiconductor substrate during the operation of the semiconductor devices in the bonded substrate.

Description:
BACKGROUND 
     The present invention relates to bonded semiconductor substrates having a cooling mechanism at or near a bonding surface and design structures for the same. 
     Heat dissipation in a semiconductor chip is a major challenge to scaling of semiconductor devices because the power density, which is the product of areal device density and power consumption per device, of the semiconductor chip increases as the average area of the semiconductor decreases. Managing heat dissipation in a bonded semiconductor substrate, in which at least two semiconductor substrates each containing semiconductor devices are bonded, becomes even more problematic because the vertical stacking of the at least two semiconductor substrates further increases power dissipater per unit area. 
     While prior art methods provide methods of cooling a single semiconductor chip such as attaching a heat sink to the semiconductor chip and forming a cooling structure within a substrate, such methods require many processing steps for the manufacture of the cooling structure or provide inadequate cooling. Particularly, prior art methods do not provide inexpensive and effective cooling mechanisms for a bonded semiconductor substrate, within which heat is generated by semiconductor devices in at least two semiconductor substrates. 
     In view of the above, there exists a need for a semiconductor structure including a cooling mechanism for a bonded semiconductor substrate, and a design structure for the same. 
     SUMMARY 
     The present invention provides a structure, design structure and methods of forming a bonded semiconductor substrate having a cooling mechanism. 
     In the present invention, a bonded substrate comprising two semiconductor substrates is provided. Each semiconductor substrate includes semiconductor devices. At least one through substrate via is provided between the two semiconductor substrates to provide a signal path therebetween. The bottom sides of the two semiconductor substrate are bonded by at least one bonding material layer that contains a cooling mechanism. In one embodiment, the cooling mechanism is a cooling channel through which a cooling fluid flows to cool the bonded semiconductor substrate during the operation of the semiconductor devices in the bonded substrate. In another embodiment, the cooling mechanism is a conductive cooling fin with two end portions and a contiguous path therebetween. The cooling fin is connected to heat sinks to cool the bonded semiconductor substrate during the operation of the semiconductor devices in the bonded substrate. 
     According to an aspect of the present invention, a semiconductor structure is provided, which comprises: 
     a first semiconductor substrate including at least one first semiconductor device; 
     a second semiconductor substrate including at least one second semiconductor device and underlying the first semiconductor substrate; and 
     a dielectric material layer located between the first semiconductor substrate and the second semiconductor substrate and including a contiguous cavity having a first lateral opening and a second lateral opening, wherein the first semiconductor substrate and the second semiconductor substrate are bonded through the dielectric material layer. 
     According to another aspect of the present invention, a semiconductor structure is provided, which comprises: 
     a first semiconductor substrate including at least one first semiconductor device; 
     a second semiconductor substrate including at least one second semiconductor device and underlying the first semiconductor substrate; 
     a dielectric material layer located between the first semiconductor substrate and the second semiconductor substrate, wherein the first semiconductor substrate and the second semiconductor substrate are bonded through the dielectric material layer; and 
     a conductive fin having a first end portion and a second end portion and an embedded portion therebetween, wherein the embedded portion is embedded in the dielectric material layer. 
     According to yet another aspect of the present invention, a design structure embodied in a machine readable medium for designing, manufacturing, or testing a design for a semiconductor structure is provided. The design structure comprises: 
     a first data representing a first semiconductor substrate including at least one first semiconductor device; 
     a second data representing a second semiconductor substrate including at least one second semiconductor device and underlying the first semiconductor substrate; 
     a third data representing a dielectric material layer located between the first semiconductor substrate and the second semiconductor substrate, wherein the first semiconductor substrate and the second semiconductor substrate are bonded through the dielectric material layer; 
     a fourth data representing a contiguous cavity embedded in the dielectric material layer and having a first lateral opening and a second lateral opening; 
     a fifth data representing a through-substrate via that extends from above the at least one first semiconductor device to one of the at least one second semiconductor device; 
     an optional sixth data representing a cooling fluid filling the cavity; 
     an optional seventh data representing an inlet tube attached to the first lateral opening; and 
     an optional eighth data representing an outlet tube attached to the second lateral opening. 
     According to still another aspect of the present invention, a design structure embodied in a machine readable medium for designing, manufacturing, or testing a design for a semiconductor structure is provided. The design structure comprises: 
     a first data representing a first semiconductor substrate including at least one first semiconductor device; 
     a second data representing a second semiconductor substrate including at least one second semiconductor device and underlying the first semiconductor substrate; 
     a third data representing a dielectric material layer located between the first semiconductor substrate and the second semiconductor substrate, wherein the first semiconductor substrate and the second semiconductor substrate are bonded through the dielectric material layer; 
     a fourth data representing a conductive fin having a first end portion and a second end portion and an embedded portion therebetween, wherein the embedded portion is embedded in the dielectric material layer; and 
     a fifth data representing a through-substrate via that extends from above the at least one first semiconductor device to one of the at least one second semiconductor device. 
     In one embodiment, the fourth data represents a conductive fin having a planar top surface that is coplanar with a horizontal surface of the second dielectric material layer and a planar bottom surface that is coplanar with a horizontal surface of the second dielectric material layer, and the planar top surface is parallel to a bottom surface of the first semiconductor substrate and the planar bottom surface is parallel to a bottom surface of the second semiconductor substrate. 
     According to still another aspect of the present invention, a method of forming a semiconductor structure is provided, which comprises: 
     providing a first structure including a first semiconductor substrate having at least one first semiconductor device thereupon; 
     providing a second structure including a second semiconductor substrate having at least one second semiconductor device thereupon; 
     forming a first dielectric material layer directly on the first structure; 
     forming a second dielectric material layer directly on the second structure; 
     patterning the second dielectric material layer to form a contiguous channel having a first lateral opening and a second lateral opening; and 
     bonding the first dielectric material layer and the second dielectric material layer. 
     According to still another aspect of the present invention, a method of forming a semiconductor structure is provided, which comprises: 
     providing a first structure including a first semiconductor substrate having at least one first semiconductor device thereupon; 
     providing a second structure including a second semiconductor substrate having at least one second semiconductor device thereupon; 
     forming a conductive fin directly on the second structure; 
     forming a second dielectric material layer directly on the second structure, wherein the conductive fin has a first end portion and a second end portion and an embedded portion therebetween, and wherein the embedded portion is embedded in the second dielectric material layer; 
     forming a first dielectric material layer directly on the first structure or directly on the second dielectric material layer; and 
     bonding the first dielectric material layer and the second dielectric material layer. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIGS. 1 ,  2 ,  4 - 6  are sequential vertical cross-sectional views of a first exemplary semiconductor structure according to a first embodiment of the present invention at various stages of a manufacturing process. 
         FIG. 3  is a horizontal cross-sectional view of the first exemplary semiconductor structure along the plane X-X′ of  FIG. 2 . The plane Y-Y′ in FIG.  3  represents the plane of the vertical cross-sectional view of  FIG. 2 . 
         FIG. 7  is a horizontal cross-sectional view of the first exemplary semiconductor structure along the plane X-X′ of  FIG. 6 . The plane Y-Y′ in  FIG. 7  represents the plane of the vertical cross-sectional view of  FIG. 6 . 
         FIGS. 8 ,  9 ,  11 - 13  are sequential vertical cross-sectional views of a second exemplary semiconductor structure according to a second embodiment of the present invention at various stages of a manufacturing process. 
         FIG. 10  is a horizontal cross-sectional view of the second exemplary semiconductor structure along the plane X-X′ of  FIG. 9 . The plane Y-Y′ in  FIG. 10  represents the plane of the vertical cross-sectional view of  FIG. 9 . 
         FIG. 14  is a horizontal cross-sectional view of the second exemplary semiconductor structure along the plane X-X′ of  FIG. 13 . The plane Y-Y′ in  FIG. 14  represents the plane of the vertical cross-sectional view of  FIG. 13 . 
         FIGS. 15 ,  16 ,  18 , and  19  are sequential vertical cross-sectional views of a third exemplary semiconductor structure according to a third embodiment of the present invention at various stages of a manufacturing process. 
         FIG. 17  is a horizontal cross-sectional view of the third exemplary semiconductor structure along the plane X-X′ of  FIG. 16 . The plane Y-Y′ in  FIG. 17  represents the plane of the vertical cross-sectional view of  FIG. 16 . 
         FIG. 20  is a horizontal cross-sectional view of the third exemplary semiconductor structure along the plane X-X′ of  FIG. 19 . The plane Y-Y′ in  FIG. 20  represents the plane of the vertical cross-sectional view of  FIG. 19 . 
         FIGS. 21 ,  22 ,  24 - 26  are sequential vertical cross-sectional views of a fourth exemplary semiconductor structure according to a fourth embodiment of the present invention at various stages of a manufacturing process. 
         FIG. 23  is a horizontal cross-sectional view of the fourth exemplary semiconductor structure along the plane X-X′ of  FIG. 22 . The plane Y-Y′ in  FIG. 23  represents the plane of the vertical cross-sectional view of  FIG. 22 . 
         FIGS. 27 ,  28 ,  30  and  31  are sequential vertical cross-sectional views of a fifth exemplary semiconductor structure according to a fifth embodiment of the present invention at various stages of a manufacturing process. 
         FIG. 29  is a horizontal cross-sectional view of the fifth exemplary semiconductor structure along the plane X-X′ of  FIG. 28 . The plane Y-Y′ in  FIG. 29  represents the plane of the vertical cross-sectional view of  FIG. 28 . 
         FIG. 32  is a flow diagram of a design process that may be used in design and manufacture of the semiconductor devices and circuits according to the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     As stated above, the present invention relates to bonded semiconductor substrates having a cooling mechanism at or near a bonding surface and design structures for the same, which are described herein with accompanying figures. As used herein, when introducing elements of the present invention or the preferred embodiments thereof, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of the elements. Throughout the drawings, the same reference numerals or letters are used to designate like or equivalent elements. Detailed descriptions of known functions and constructions unnecessarily obscuring the subject matter of the present invention have been omitted for clarity. The drawings are not necessarily drawn to scale. 
     Referring to  FIG. 1 , a first exemplary semiconductor structure according to a first embodiment of the present invention comprises a first structure  99  derived from a first substrate (substrate  1 ) and a second structure  199 , derived from a second substrate (substrate  2 ). The first structure  99  comprises a first semiconductor substrate  140  including at least one first semiconductor device. For example, the at least one first semiconductor device may include a first field effect transistor having a body region  122  and source and drain regions  124  in the first semiconductor substrate  140  and a gate electrode  142  and a gate spacer  144  directly on and above the first semiconductor substrate  140 . The at least one first semiconductor device is electrically isolated from one another by at least one first shallow trench isolation structure  130  that extends from a top surface of the first semiconductor substrate  140  to a bottom surface of the first semiconductor substrate  140 . 
     A portion of the at least one first semiconductor device is located within a semiconductor portion of the first semiconductor substrate  140 , which comprises a semiconductor material. The semiconductor material may comprise silicon, germanium, silicon-germanium alloy, silicon carbon alloy, silicon-germanium-carbon alloy, gallium arsenide, indium arsenide, indium phosphide, III-V compound semiconductor materials, II-VI compound semiconductor materials, organic semiconductor materials, and other compound semiconductor materials. Typically, the semiconductor material of the semiconductor portion of the first semiconductor substrate  140  comprises an epitaxial semiconductor material, i.e., a single crystalline semiconductor material having atomic alignment throughout the semiconductor material. 
     Optionally, a first insulator layer  120  may be provided directly underneath the first semiconductor substrate  140 . The first insulator layer  120  comprises a dielectric material such as silicon oxide or silicon nitride. A substrate-contact level metal interconnect structure  160  is formed directly on the at least one first semiconductor device and the first semiconductor substrate  140 . The substrate-contact level metal interconnect structure  160  includes a substrate-contact level dielectric layer  150 . The substrate-contact level dielectric layer  150  comprises a dielectric material. The dielectric materials that may be used for the substrate-contact level dielectric layer  150  include, but are not limited to, a silicate glass, an organosilicate glass (OSG) material, a SiCOH-based low-k material formed by chemical vapor deposition, a spin-on glass (SOG), or a spin-on low-k dielectric material such as SiLK™, etc. The silicate glass includes an undoped silicate glass (USG), borosilicate glass (BSG), phosphosilicate glass (PSG), fluorosilicate glass (FSG), borophosphosilicate glass (BPSG), etc. The dielectric material may be a low dielectric constant (low-k) material having a dielectric constant less than 3.0. The dielectric material may non-porous or porous. First contact vias  148  that contact the at least one first semiconductor device and having a top surface coplanar with the top surface of the substrate-contact level dielectric layer  160  are formed within the substrate-contact level dielectric layer  150 . First contact vias  148  comprise a conductive material such as W, Cu, Al, TaN, TiN, Ta, Ti, or a combination thereof. 
     A top handle substrate  181  is attached to the top surface of the substrate-contact level metal interconnect structure  160 , for example, by bonding. The top handle substrate  180  may comprise a ceramic material, a semiconductor material, or a dielectric material such as glass or aluminum oxide. The top handle substrate  181  provides mechanical support to the stack of the first semiconductor substrate  140  and the substrate-contact level metal interconnect structure  160 , and optionally, the first insulator layer  120 , if present. 
     Insulator layer  120  could the insulator in a silicon-on-insulator (SOI) wafer, which was originally composed of a silicon handle wafer, an insulator, and a silicon layer on the surface. If a SOI wafer was used to form the structures on wafer  1 , then the upper surface of wafer  1  would be temporarily attached to a top handle substrate  181  and the original silicon handle on the SOI wafer would be removed by a combination of etching or backside grinding, as known in the art. Alternatively, the stack of the first semiconductor substrate  140  and the substrate-contact level metal interconnect structure  160 , and optionally, the first insulator layer  120 , may be provided by cleaving a portion of a semiconductor substrate after attaching the top handle substrate  181  to the top surface of the substrate-contact level metal interconnect structure  160 . For example, the first semiconductor substrate  140  and the first insulator layer  120  may be an upper portion of a semiconductor-on-insulator (SOI) layer, in which first semiconductor substrate  140  is a top semiconductor layer and the first insulator layer  120  is a buried insulator layer. Alternately, the first semiconductor substrate  140  may be a top portion of a bulk substrate, and the first insulator layer  120  may be absent in the first structure  99 . In this case, the first semiconductor substrate  140  may be separated from the rest of the bulk substrate, for example, by backside grinding or backside etching the substrate, or cleaving at a hydrogen implanted surface. 
     The thickness of the first semiconductor substrate  140  may be from about 50 nm to about 200 μm, and typically from about 100 nm to about 20 μm, although lesser and greater thicknesses are contemplated herein. The thickness of the first insulator layer  120 , if present, may be from about 100 nm to about 10 μm, and typically from about 200 nm to about 1.0 μm, although lesser and greater thicknesses are also contemplated herein. The thickness of the substrate-contact level metal interconnect structure  160  may be from about 200 nm to about 1.0 μm, although lesser and greater thicknesses are also contemplated herein. The thickness of the top handle substrate  181  may be from about 400 μm to about 2,000 μm, although lesser and greater thicknesses are also contemplated herein. The thickness of the first dielectric layer  110  may be from about 50 nm to about 5 μm, and typically from about 200 nm to about 2 μm, although lesser and greater thicknesses are also contemplated herein. 
     After flipping the first structure  99  upside down, a first dielectric layer  110  is applied to the bottom surface of the first insulator layer  120  or to the bottom surface of the first semiconductor substrate  140  if the first insulator layer  120  is not present. The first dielectric layer  110  comprises a bondable material that may be employed for bonding purposes, which may be a bondable dielectric oxide such as silicon oxide or a bondable polymer such as polyimide. The first dielectric layer  110  is lithographically patterned to include a contiguous channel embedded in the first dielectric layer  110  and having a first lateral opening at a first end of the contiguous channel and a second lateral opening at a second end of the contiguous channel. The stack of the first structure  99  and the first dielectric layer  110  is flipped upside down so that the first dielectric layer  110  is located underneath the first structure  99 . 
     The second structure  199  comprises a second semiconductor substrate  240  including at least one second semiconductor device, which is shown upside down so that the top surface of the second semiconductor substrate  240  is shown below the bottom surface of the second semiconductor substrate  240 . For example, the at least one second semiconductor device may include a second field effect transistor having a body region  222  and source and drain regions  224  in the second semiconductor substrate  240  and a gate electrode  242  and a gate spacer  244  directly on and beneath the first semiconductor substrate  140  as positioned upside down. The at least one second semiconductor device is electrically isolated from one another by at least one second shallow trench isolation structure  230  that extends from a top surface of the second semiconductor substrate  240  to a bottom surface of the second semiconductor substrate  240 . 
     A portion of the at least one second semiconductor device is located within a semiconductor portion of the second semiconductor substrate  240 , which comprises a semiconductor material. The semiconductor material in the second semiconductor substrate  240  may comprise any material that may be employed for the first semiconductor substrate  140  as described above. Typically, the semiconductor material of the second semiconductor substrate  240  comprises an epitaxial, polycrystalline, or monocrystalline semiconductor material. 
     Optionally, a second insulator layer  220  may be provided directly on the top surface of the second semiconductor substrate  240 . The second insulator layer  220  comprises a dielectric material such as silicon oxide or silicon nitride, and may consist of the insulator portion of an SOI substrate, as in the substrate  99  discussed above. A second metal interconnect structure  260  is formed directly on the at least one first semiconductor device and the second semiconductor substrate  240  employing methods known in the art. The second metal interconnect structure  260  includes second interconnect level dielectric layers  250  and second metal wiring structures  248  embedded therein. The second interconnect level dielectric layers  250  may comprise any of the dielectric materials that may be employed for the substrate-contact level metal interconnect structure  160  as described above. A second passivation layer  290  is formed on the top surface of the second metal interconnect structure  260 . The second passivation layer  290  comprises a dielectric material such as silicon oxide, silicon nitride, or a combination thereof. 
     A bottom handle substrate  296  is attached to the top surface of the passivation layer  290 , for example, by bonding. The bottom handle substrate  296  is similar to handle substrate  181  and may comprise a ceramic material, a semiconductor material, or a dielectric material such as glass or aluminum oxide. The bottom handle substrate  296  provides mechanical support to the stack of the second semiconductor substrate  240  and the second metal interconnect structure  260 , and optionally, the second insulator layer  220 , if present. 
     The stack of the second semiconductor substrate  240  and the second metal interconnect structure  260 , and optionally, the second insulator layer  220 , may be provided in a similar fashion as the stack of the first semiconductor substrate  140  was, i.e., by cleaving a portion of a semiconductor substrate after attaching the bottom handle substrate  296  to the top surface of the passivation layer  290 , or removing the slower silicon layer from an SOI substrate. For example, the second semiconductor substrate  240  and the second insulator layer  220  may be an upper portion of a semiconductor-on-insulator (SOI) layer, in which the second semiconductor substrate  240  is a top semiconductor layer and the second insulator layer  220  is a buried insulator layer. Alternately, the second semiconductor substrate  240  may be a top portion of a bulk substrate, and the second insulator layer  120  may be absent in the second structure  99 . In this case, the second semiconductor substrate  240  may be separated from the rest of the bulk substrate, for example, by cleaving at a hydrogen implanted surface. 
     The thickness of the second semiconductor substrate  240  may be from about 50 nm to about 200 μm, and typically from about 100 nm to about 20 μm, although lesser and greater thicknesses are contemplated herein. The thickness of the second insulator layer  220 , if present, may be from about 100 nm to about 10 μm, and typically from about 200 nm to about 1.0 μm, although lesser and greater thicknesses are also contemplated herein. The thickness of the second metal interconnect structure  260  may be from about 0.2 μm to about 20 μm, although lesser and greater thicknesses are also contemplated herein. The thickness of the bottom handle substrate  296  may be from about 400 μm to about 2,000 μm, although lesser and greater thicknesses are also contemplated herein. The thickness of the second dielectric layer  210  may be from about 50 nm to about 5 μm, and typically from about 200 nm to about 2 μm, although lesser and greater thicknesses are also contemplated herein. 
     The stack of the second semiconductor substrate  240  and second metal interconnect structure  260 , and the second insulator layer  220 , if present, are positioned upside down in the second structure  199 . A second dielectric layer  210  is applied to the bottom surface of the second insulator layer  220  or to the bottom surface of the second semiconductor substrate  140  if the second insulator layer  220  is not present. The second dielectric layer  210  comprises a bondable material that may be employed for bonding purposes, which may be a bondable dielectric oxide such as silicon oxide or a bondable polymer such as polyimide. The second dielectric layer  210  is lithographically patterned to include a contiguous channel embedded in the second dielectric layer  210  and having a third lateral opening at a first end of the contiguous channel and a fourth lateral opening at a second end of the contiguous channel. In one case, the pattern in the second dielectric layer  210  is a mirror image of the pattern in the first dielectric layer  110 . 
     Referring to  FIGS. 2 and 3 , the first structure  99  and the second structure  199  are bonded through the first dielectric layer  110  and the second dielectric layer  210 . The first structure  99 , the second structure  199 , the first dielectric layer  110 , and the second dielectric layer  210  collectively constitute a bonded substrate. The top surface of the second dielectric layer  210  is bonded to the top surface of the first dielectric layer  110  as positioned upside down. When the second dielectric layer  210  and the first dielectric layer  110  are brought together, the patterns in the second dielectric layer  210  and the first dielectric layer  110  are aligned so that the two channels form an contiguous cavity  100  vertically bounded by an upper surface of the first dielectric layer  110  and a lower surface of the second dielectric layer  210 . The contiguous cavity  100  is laterally bounded by sidewalls of the first dielectric layer  110  and a lower surface of the second dielectric layer  210 . The contiguous cavity  100  is provided with a first lateral opening at a first end of the contiguous cavity  100  and a second lateral opening at a second end of the contiguous cavity  100 . The contiguous cavity  100  has a shape of a pipe, and may include bends. The contiguous cavity  100  is configured to be conducive to fluid flow between the first lateral opening and the second lateral opening, and may include regions having a constant cross-sectional area. The contiguous cavity  100  is “contiguous,” i.e., in one connected volume. The vertical height of the contiguous cavity  100  may be from about 100 nm to about 10 μm, and typically from about 400 nm to about 4 μm, although lesser and greater thicknesses are also contemplated herein. 
     While the present invention is described with the first dielectric layer  110  and the second dielectric layer  210  that are bonded together so that the bonded interface is formed between the first dielectric layer  110  and the second dielectric layer  210 , embodiments are explicitly contemplated in which only one of the first dielectric layer  110  and the second dielectric layer  210  is employed to bond the first structure  99  and the second structure  199 . In this case, one of the first dielectric layer  110  and the second dielectric layer  210  containing a channel is vertically abutted by the first structure  99  and the second structure  199 . In one embodiment, channel  100  has width and height of 10 um and 4 um, respectively. Although perfect alignment between layers  110  and  210  is shown in  FIG. 2 , layers  110  and  210  may have some misalignment due to overlay variations and width differences between the two layers. 
     Referring to  FIG. 4 , the top handle substrate  181  is removed from the top surface of the substrate-contact level metal interconnect structure  160 . Through-substrate via holes are formed from the top surface of the substrate-contact level metal interconnect structure  160  through the at least one shallow trench isolation structure  130  within the first semiconductor substrate  140 , the first insulator layer  120  if present, the first dielectric layer  110 , the second dielectric layer  210 , and the second insulator layer  220  if present, to upper portions of the at least one second semiconductor device located in and beneath the second semiconductor substrate  240 . For example, the through-substrate via holes may be formed to the source and drain regions  224  or the body region  222  of a field effect transistor located in and below the second semiconductor layer. 
     The through-substrate via holes are filled with a conductive material such as a doped semiconductor material or a metallic material to form conductive through-substrate vias  146 . The excess conductive material above the top surface of the substrate-contact level metal interconnect structure  160  is removed, for example, by planarization. Exemplary semiconductor materials that may be employed for the through-substrate vias  146  include doped polycrystalline or amorphous silicon, germanium, silicon germanium, a metal (e.g., tungsten, titanium, tantalum, ruthenium, cobalt, copper, aluminum, lead, platinum, tin, silver, gold), a conducting metallic compound material (e.g., tantalum nitride, titanium nitride, tungsten silicide, tungsten nitride, titanium nitride, tantalum nitride, ruthenium oxide, cobalt silicide, nickel silicide), carbon nanotube, conductive carbon, or any suitable combination thereof. The through substrate vias  146  extend from the above the at least one first semiconductor device in the first semiconductor layer  120 , i.e., from the top surface of the substrate-contact level metal interconnect structure  160 , to the at least one second semiconductor device. 
     Referring to  FIG. 5 , a first metal interconnect structure  180  is formed directly on the substrate-contact level metal interconnect structure  160  employing methods known in the art. The first metal interconnect structure  180  includes first interconnect level dielectric layers  170  and first metal wiring structures  168  embedded therein. The first interconnect level dielectric layers  170  may comprise any of the dielectric materials that may be employed for the substrate-contact level metal interconnect structure  160  as described above. A first passivation layer  290  is formed on the top surface of the first metal interconnect structure  180 . The first passivation layer  190  comprises a dielectric material such as silicon oxide, silicon nitride, or a combination thereof. 
     The first metal wiring structures  168  may include a first set of Controlled Collapse Chip Connection (C4) pads located directly underneath the first passivation layer  190 . The first passivation layer  190  is lithographically patterned to expose the first set of C4 pads. A first set of C4 balls  192  are formed on the exposed first set of C4 pads. The first set of C4 balls  192  may then be bonded to a packaging substrate or another semiconductor chip including a set of C4 pads. 
     Referring to  FIGS. 6 and 7 , the bottom handle substrate  296  is removed off the second passivation layer  290 . The second metal wiring structures  248  may include a second set of C4 pads located directly above the second passivation layer  190 . The second passivation layer  290  is lithographically patterned to expose the second set of C4 pads. A second set of C4 balls  292  are formed on the exposed second set of C4 pads. The second set of C4 balls  292  may then be bonded to a packaging substrate or yet another semiconductor chip including a set of C4 pads for further vertical stacking of semiconductor chips. 
     An inlet tube  400  may be attached to the first lateral opening of the contiguous cavity  100 , and an outlet tube  410  may be attached to the second lateral opening of the contiguous cavity  100  to facilitate connection to a cooling fluid supply line (not shown) and a cooling fluid return line (not shown), which are connected to a cooling fluid circulator (not shown) and an optional heat radiator. A cooling fluid is supplied into the contiguous cavity  100  and circulated through the contiguous cavity  100  during operation of the semiconductor devices in the bonded semiconductor substrate, which may include, from top to bottom, the first set of C4 pads, the first passivation layer  190 , the first metal interconnect structure  180 , the substrate-contact level metal interconnect structure  160 , the first semiconductor substrate  140 , the first insulator layer  120 , the first dielectric layer  110 , the second dielectric layer  210 , the second insulator layer  220 , the second semiconductor substrate  240 , the second metal interconnect structure  260 , the second passivation layer  290 , and the second set of C4 pads  292 . 
     The cooling fluid may comprise any fluid that may be circulated to transfer heat. The cooling fluid may be a liquid or a gas. Exemplary materials for the cooling fluid include, but are not limited to, liquid helium, liquid hydrogen, liquid nitrogen, liquid oxygen, water, glycerin, methyl alcohol, ethyl alcohol, isopropyl alcohol, water, an antifreeze solution, a mineral oil, a castor oil, a silicone oil, a fluorocarbon oil, a transformer oil, a cutting lubricant, a refrigerant, air, nitrogen gas, oxygen gas, an inert gas, a halomethane, anhydrous ammonia, sulfur dioxide, carbon dioxide, and a non-reactive combination thereof. 
     Referring to  FIG. 8 , a second exemplary structure according to a second embodiment of the present invention comprises a first structure  99  and a second structure  199 , which may be the same as in the first embodiment. After flipping the first structure  99  upside down, a first dielectric layer  110  is applied to the bottom surface of the first insulator layer  120  or to the bottom surface of the first semiconductor substrate  140  in the same manner as in the first embodiment. The first dielectric layer  110  comprises a bondable material that may be employed for bonding purposes. The first dielectric layer  110  is lithographically patterned to include a contiguous channel embedded in the first dielectric layer  110  and having a first lateral opening at a first end of the contiguous channel and a second lateral opening at a second end of the contiguous channel. The stack of the first structure  99  and the first dielectric layer  110  is flipped upside down so that the first dielectric layer  110  is located underneath the first structure  99 . 
     A bottom handle substrate  296  is attached to the top surface of the passivation layer  290 , for example, by bonding, in the same manner as in the first embodiment. At least one conductive structure  202  is then formed on the second insulator layer  220 . The at least one conductive structure  202  is formed by lithographic patterning of at least one via hole in the second insulator layer  220  that extends to a top portion of the at least one second semiconductor device in and beneath the second semiconductor substrate  240 . For example, the at least one via hole may extend to an upper surface of the second semiconductor substrate  240 , which is the bottom surface of the second semiconductor substrate  240  as positioned upside down. A conductive material is deposited into the at least one via hole and on the upper surface of the second insulator layer  220  or the second semiconductor substrate  240 . The conductive material may be a doped semiconductor material such as doped polysilicon or a doped silicon-containing alloy, or may be a metallic material such as W, Cu, Al, TaN, TiN, Ta, Ti, etc. The conductive material is lithographically patterned above the upper surface of the second insulator layer  220  to form the at least one conductive structure  202 . The thickness of the at least one conductive structure  202  may be from about 50 nm to about 5 μm, and typically from about 200 nm to about 2 μm, although lesser and greater thicknesses are also contemplated herein. 
     A second dielectric layer  210  is applied over the second insulator layer  220  or the first semiconductor substrate  140 . The second dielectric layer  210  may be subsequently planarized so that the top surface of the second dielectric layer  210  is substantially coplanar with the top surface(s) of the at least one conductive structure  202 . The second dielectric layer  210  comprises a bondable material that may be employed for bonding purposes as in the first embodiment. The second dielectric layer  210  is lithographically patterned to include a contiguous channel embedded in the second dielectric layer  210  and having a third lateral opening at a first end of the contiguous channel and a fourth lateral opening at a second end of the contiguous channel. Each of the at least one conductive structure  202  is laterally embedded in the second dielectric layer  210 . In one case, the pattern in the second dielectric layer  210  is a mirror image of the pattern in the first dielectric layer  110  so that the sidewalls of the second dielectric layer  210  and the first dielectric layer  110  are substantially vertically coincident when the second dielectric layer  210  and the first dielectric layer  110  are brought together. 
     Referring to  FIGS. 9 and 10 , the first structure  99  and the second structure  199  are bonded through the first dielectric layer  110  and the second dielectric layer  210  in the same manner as in the first embodiment. The first structure  99 , the second structure  199 , the first dielectric layer  110 , and the second dielectric layer  210  collectively constitute a bonded substrate. The top surface of the second dielectric layer  210  is bonded to the top surface of the first dielectric layer  110  as positioned upside down. When the second dielectric layer  210  and the first dielectric layer  110  are brought together, the patterns in the second dielectric layer  210  and the first dielectric layer  110  are aligned so that the two channels form an contiguous cavity  100  vertically bounded by an upper surface of the first dielectric layer  110  and a lower surface of the second dielectric layer  210 . The contiguous cavity  100  is laterally bounded by sidewalls of the first dielectric layer  110  and a lower surface of the second dielectric layer  210 . The contiguous cavity  100  has the same geometric features as the continuous cavity  100  in the first embodiment. Embodiments are explicitly contemplated in which only one of the first dielectric layer  110  and the second dielectric layer  210  is employed to bond the first structure  99  and the second structure  199 . 
     Referring to  FIG. 11 , the top handle substrate  181  is removed from the top surface of the substrate-contact level metal interconnect structure  160 . Through-substrate via holes are formed from the top surface of the substrate-contact level metal interconnect structure  160  through the at least one shallow trench isolation structure  130  within the first semiconductor substrate  140 , the first insulator layer  120  if present, and the first dielectric layer  110 , to upper portions of the at least one conductive structure  202  embedded in the second dielectric layer  210 . 
     The through-substrate via holes are filled with a conductive material such as a doped semiconductor material or a metallic material to form through-substrate vias  146 . The excess conductive material above the top surface of the substrate-contact level metal interconnect structure  160  is removed, for example, by planarization. The through-substrate vias  146  may comprise the same material as in the first embodiment. The through substrate vias  146  extend from the above the at least one first semiconductor device in the first semiconductor layer  120 , i.e., from the top surface of the substrate-contact level metal interconnect structure  160 , to the at least one conductive structure  202 . The through substrate vias  146  and the at least one conductive structure  202  collectively constitute conductive electrical connections between the at least one first semiconductor device and the at least one second semiconductor device. 
     Referring to  FIG. 12 , a first metal interconnect structure  180  is formed directly on the substrate-contact level metal interconnect structure  160  in the same manner as in the first embodiment. The first metal wiring structures  168  may include a first set of Controlled Collapse Chip Connection (C4) pads located directly underneath the first passivation layer  190  as in the first embodiment. A first set of C4 balls  192  may be formed on the exposed first set of C4 pads as in the first embodiment. 
     Referring to  FIGS. 13 and 14 , the bottom handle substrate  296  is removed off the second passivation layer  290 . A second set of C4 balls  292  may be formed on an exposed second set of C4 pads as in the first embodiment. An inlet tube  400  and an outlet tube  410  may be attached to the contiguous cavity  100  to facilitate connection to a cooling fluid supply line (not shown) and a cooling fluid return line (not shown), which are connected to a cooling fluid circulator (not shown) and an optional heat radiator. A cooling fluid is supplied into the contiguous cavity  100  and circulated through the contiguous cavity  100  during operation of the semiconductor devices in the bonded semiconductor substrate in the same manner as in the first embodiment. 
     Referring to  FIG. 15 , a third exemplary structure according to a third embodiment of the present invention comprises a first structure  99  and a second structure  199 , which may be the same as in the first embodiment. After flipping the first structure  99  upside down, a first dielectric layer  110  is applied to the bottom surface of the first insulator layer  120  or to the bottom surface of the first semiconductor substrate  140  in the same manner as in the first embodiment. The first dielectric layer  110  comprises a bondable material that may be employed for bonding purposes. The first dielectric layer  110  is lithographically patterned to include a contiguous channel embedded in the first dielectric layer  110  and having a first lateral opening at a first end of the contiguous channel and a second lateral opening at a second end of the contiguous channel. The stack of the first structure  99  and the first dielectric layer  110  is flipped upside down so that the first dielectric layer  110  is located underneath the first structure  99 . 
     A bottom handle substrate  296  is attached to the top surface of the passivation layer  290 , for example, by bonding, in the same manner as in the first embodiment. At least one conductive structure  202  and at least one conductive wiring structure  203  are formed on the second insulator layer  220 . The at least one conductive structure  202  and at least one conductive wiring structure  203  are formed by lithographic patterning of via holes in the second insulator layer  220  that extend to top portions of the at least one second semiconductor device in and beneath the second semiconductor substrate  240 . For example, the via holes may extend to an upper surface of the second semiconductor substrate  240 , which is the bottom surface of the second semiconductor substrate  240  as positioned upside down. A conductive material is deposited into the via holes and on the upper surface of the second insulator layer  220  or the second semiconductor substrate  240  in the same manner as in the second embodiment. Each of the at least one conductive wiring structure  203  provides a resistive electrical connection, i.e., conductive wiring, between one of the at least one second semiconductor device and another of the at least one second semiconductor device in the second semiconductor substrate  240 . 
     A second dielectric layer  210  is applied over the second insulator layer  220  or the first semiconductor substrate  140 . The second dielectric layer  210  may be subsequently planarized so that the top surface of the second dielectric layer  210  is substantially coplanar with the top surface(s) of the at least one conductive structure  202 . The second dielectric layer  210  comprises a bondable material that may be employed for bonding purposes as in the first and embodiments. The second dielectric layer  210  is lithographically patterned to include a contiguous channel embedded in the second dielectric layer  210  and having a third lateral opening at a first end of the contiguous channel and a fourth lateral opening at a second end of the contiguous channel. Each of the at least one conductive structure  202  and at least one conductive wiring structure  203  is laterally embedded in the second dielectric layer  210 . In one case, the pattern in the second dielectric layer  210  is a mirror image of the pattern in the first dielectric layer  110  so that the sidewalls of the second dielectric layer  210  and the first dielectric layer  110  are substantially vertically coincident when the second dielectric layer  210  and the first dielectric layer  110  are brought together. 
     Referring to  FIGS. 16 and 17 , the first structure  99  and the second structure  199  are bonded through the first dielectric layer  110  and the second dielectric layer  210  in the same manner as in the first embodiment. The first structure  99 , the second structure  199 , the first dielectric layer  110 , and the second dielectric layer  210  collectively constitute a bonded substrate. The top surface of the second dielectric layer  210  is bonded to the top surface of the first dielectric layer  110  as positioned upside down. When the second dielectric layer  210  and the first dielectric layer  110  are brought together, the patterns in the second dielectric layer  210  and the first dielectric layer  110  are aligned so that the two channels form an contiguous cavity  100  vertically bounded by an upper surface of the first dielectric layer  110  and a lower surface of the second dielectric layer  210 . The contiguous cavity  100  is laterally bounded by sidewalls of the first dielectric layer  110  and a lower surface of the second dielectric layer  210 . The contiguous cavity  100  has the same geometric features as the continuous cavity  100  in the first embodiment. Embodiments are explicitly contemplated in which only one of the first dielectric layer  110  and the second dielectric layer  210  is employed to bond the first structure  99  and the second structure  199 . 
     Referring to  FIG. 18 , the top handle substrate  181  is removed from the top surface of the substrate-contact level metal interconnect structure  160 . Through-substrate vias  146  are formed in the same manner as in the second embodiment. The through substrate vias  146  and the at least one conductive structure  202  collectively constitute conductive electrical connections between the at least one first semiconductor device and the at least one second semiconductor device. 
     Referring to  FIGS. 19 and 20 , a first metal interconnect structure  180  is formed directly on the substrate-contact level metal interconnect structure  160  in the same manner as in the first and second embodiments. The first metal wiring structures  168  may include a first set of Controlled Collapse Chip Connection (C4) pads located directly underneath the first passivation layer  190  as in the first embodiment. A first set of C4 balls  192  may be formed on the exposed first set of C4 pads as in the first embodiment. The bottom handle substrate  296  is then removed off the second passivation layer  290 . A second set of C4 balls  292  may be formed on an exposed second set of C4 pads as in the first and second embodiments. An inlet tube  400  and an outlet tube  410  may be attached to the contiguous cavity  100  to facilitate connection to a cooling fluid supply line (not shown) and a cooling fluid return line (not shown), which are connected to a cooling fluid circulator (not shown) and an optional heat radiator. A cooling fluid is supplied into the contiguous cavity  100  and circulated through the contiguous cavity  100  during operation of the semiconductor devices in the bonded semiconductor substrate in the same manner as in the first and second embodiments. 
     Referring to  FIG. 21 , a fourth exemplary structure according to a fourth embodiment of the present invention comprises a first structure  99  and a second structure  199 , which may be the same as in the first through third embodiments. A conductive fin  302  having a first end portion and a second end portion and a middle portion connecting the first end portion and the second end portion. The conductive fin  302  may be formed by deposition of a conductive material directly on the upper surface of the second insulator layer  220 , followed by lithographic patterning. The conductive fin  302  may comprise a semiconductor material such as doped polysilicon or a doped silicon-containing alloy, or may comprise a metallic material such as Cu, W, Al, Ti, Ta, Co, Ni, TaN, TiN, etc. The conductive fin  302  is of integral and unitary construction, i.e., in the shape of a single contiguous piece without any interface therein. The conductive fin  302  may include bends, and may include regions having a constant cross-sectional area. The conductive fin  302  is configured allow heat transfer from the middle portion to the first end portion and/or the second end portion. The thickness of the conductive fin  302  may be from about 100 nm to about 10 μm, and typically from about 400 nm to about 4 μm, although lesser and greater thicknesses are also contemplated herein. 
     A second dielectric layer  210  is applied over the conductive fin  302  and one of the second insulator layer  220  and the first semiconductor substrate  140 . The second dielectric layer  210  may be subsequently planarized so that the top surface of the second dielectric layer  210  is substantially coplanar with the top surface of the conductive fin  302 . The second dielectric layer  210  comprises a bondable material that may be employed for bonding purposes as in the first through third embodiments. 
     In one case, a first dielectric material layer  310  is applied over the second dielectric material layer  210 . The first dielectric layer  310  comprises a bondable material, and may comprise any of the materials that may be employed for the first dielectric layer  110  in the first through third embodiments. The thickness of the first dielectric material layer  310  may be from about 50 nm to about 5 μm, and typically from about 200 nm to about 2 μm, although lesser and greater thicknesses are also contemplated herein. 
     In another case, the first structure  99  is flipped upside down, and a first dielectric layer  310  is applied to the bottom surface of the first insulator layer  120  or to the bottom surface of the first semiconductor substrate  140  in the same manner as in the first through third embodiments. The first dielectric layer  310  comprises the same bondable material as the first dielectric material layer  110  of the first through third embodiments. The thickness of the first dielectric material layer  310  may be from about 50 nm to about 5 μm, and typically from about 200 nm to about 2 μm, although lesser and greater thicknesses are also contemplated herein. 
     Preferably, the second dielectric material layer  210  and/or the first dielectric material layer  310  are lithographically patterned to expose the first end portion and the second end portion of the conductive fin  302 , while the middle portion of the conductive fin  302  is embedded in the second dielectric layer  210 . Thus, the first end portion and the second end portion of the conductive fin  302  protrude out of the sidewalls of the second dielectric material layer  210  and/or the sidewalls of the first dielectric material layer  310 . 
     Referring to  FIGS. 22 and 23 , the first structure  99  and the second structure  199  are bonded through the first dielectric layer  310  and the second dielectric layer  210 . In one case, the bonding interface may be between the bottom surface of the first insulator layer  120  and the top surface of the first dielectric layer  310  as deposited directly on the top surface of the second dielectric layer  210 . In another case, the bonding interface may be between the top surface of the second dielectric layer  210  and the top surface of the first dielectric layer  310  as positioned upside down in the same manner as in the first through third embodiments. The first structure  99 , the second structure  199 , the first dielectric layer  310 , the second dielectric layer  210 , and the conductive fin  302  collectively constitute a bonded substrate. Embodiments are explicitly contemplated in which only the second dielectric layer  210  is employed to bond the first structure  99  and the second structure  199  without employing the first dielectric layer  110 . 
     Referring to  FIG. 24 , the top handle substrate  181  is removed from the top surface of the substrate-contact level metal interconnect structure  160 . Through-substrate vias  146  are formed in the same manner as in the second embodiment. The through substrate vias  146  constitute conductive electrical connections between the at least one first semiconductor device and the at least one second semiconductor device. 
     Referring to  FIG. 25 , a first metal interconnect structure  180  is formed directly on the substrate-contact level metal interconnect structure  160  in the same manner as in the first and second embodiments. The first metal wiring structures  168  may include a first set of Controlled Collapse Chip Connection (C4) pads located directly underneath the first passivation layer  190  as in the first embodiment. A first set of C4 balls  192  may be formed on the exposed first set of C4 pads as in the first embodiment. 
     Referring to  FIG. 26 , the bottom handle substrate  296  is then removed off the second passivation layer  290 . A second set of C4 balls  292  may be formed on an exposed second set of C4 pads as in the first and second embodiments. The first end portion and the second end portion of the conductive fin  302  are connected to a heat sink structure so that heat generated by semiconductor devices in the first and second semiconductor substrates ( 140 ,  240 ) are transferred through the middle portion, which is the embedded portion, of the conductive fin  302  through the first and second end portions of the conductive fin  302 , and then to the heat sink structure. 
     Referring to  FIG. 27 , a fifth exemplary structure according to a fifth embodiment of the present invention comprises a first structure  99  and a second structure  199 , which may be the same as in the first through fourth embodiments. 
     A conductive fin  302 , at least one conductive structure  202 , and at least one conductive wiring structure  203  are formed on the second insulator layer  220 . The at least one conductive structure  202  and the at least one conductive wiring structure  203  are formed by lithographic patterning of via holes in the second insulator layer  220  that extend to top portions of the at least one second semiconductor device in and beneath the second semiconductor substrate  240 . For example, the via holes may extend to an upper surface of the second semiconductor substrate  240 , which is the bottom surface of the second semiconductor substrate  240  as positioned upside down. A conductive material is deposited into the via holes and on the upper surface of the second insulator layer  220  or the second semiconductor substrate  240  in the same manner as in the second and third embodiments. The conductive material is lithographically patterned to form the conductive fin  302 , the at least one conductive structure  202 , and the at least one conductive wiring structure  203 . The conductive fin  302  may have the same structure and composition as in the fourth embodiment. The at least one conductive structure  202  and the at least one conductive wiring structure  203  has the same composition as the conductive fin  302 , and has the same structural and functional characteristics as the at least one conductive structure  202  and the at least one conductive wiring structure  203  of the third embodiment. Each of the at least one conductive wiring structure  203  provides a resistive electrical connection, i.e., conductive wiring, between one of the at least one second semiconductor device and another of the at least one second semiconductor device in the second semiconductor substrate  240 . 
     In one case, a first dielectric material layer  310  is applied over the second dielectric material layer  210 . The first dielectric layer  310  comprises a bondable material, and may comprise any of the material that may be employed for the first dielectric layer  110  in the first through third embodiments. The thickness of the first dielectric material layer  310  may be from about 50 nm to about 5 μm, and typically from about 200 nm to about 2 μm, although lesser and greater thicknesses are also contemplated herein. 
     In another case, the first structure  99  is flipped upside down, and a first dielectric layer  310  is applied to the bottom surface of the first insulator layer  120  or to the bottom surface of the first semiconductor substrate  140  in the same manner as in the first through third embodiments. The first dielectric layer  310  comprises the same bondable material as the first dielectric material layer  110  of the first through third embodiments. The thickness of the first dielectric material layer  310  may be from about 50 nm to about 5 μm, and typically from about 200 nm to about 2 μm, although lesser and greater thicknesses are also contemplated herein. 
     Preferably, the second dielectric material layer  210  and/or the first dielectric material layer  310  are lithographically patterned to expose the first end portion and the second end portion of the conductive fin  302 , while the middle portion of the conductive fin  302  is embedded in the second dielectric layer  210 . Thus, the first end portion and the second end portion of the conductive fin  302  protrude out of the sidewalls of the second dielectric material layer  210  and/or the sidewalls of the first dielectric material layer  310 . 
     Referring to  FIGS. 28 and 29 , the first structure  99  and the second structure  199  are bonded through the first dielectric layer  310  and the second dielectric layer  210 . In one case, the bonding interface may be between the bottom surface of the first insulator layer  120  and the top surface of the first dielectric layer  310  as deposited directly on the top surface of the second dielectric layer  210 . In another case, the bonding interface may be between the top surface of the second dielectric layer  210  and the top surface of the first dielectric layer  310  as positioned upside down in the same manner as in the first through third embodiments. The first structure  99 , the second structure  199 , the first dielectric layer  310 , the second dielectric layer  210 , the conductive fin  302 , and the at least one conductive structure  202 , and the at least one conductive wiring structure  203  collectively constitute a bonded substrate. Embodiments are explicitly contemplated in which only the second dielectric layer  210  is employed to bond the first structure  99  and the second structure  199  without employing the first dielectric layer  110 . 
     Referring to  FIG. 30 , the top handle substrate  181  is removed from the top surface of the substrate-contact level metal interconnect structure  160 . Through-substrate vias  146  are formed in the same manner as in the second and third embodiments. The through substrate vias  146  and the at least one conductive structure  202  collectively constitute conductive electrical connections between the at least one first semiconductor device and the at least one second semiconductor device. 
     Referring to  FIG. 31 , a first metal interconnect structure  180  is formed directly on the substrate-contact level metal interconnect structure  160  in the same manner as in the first and second embodiments. The first metal wiring structures  168  may include a first set of Controlled Collapse Chip Connection (C4) pads located directly underneath the first passivation layer  190  as in the first embodiment. A first set of C4 balls  192  may be formed on the exposed first set of C4 pads as in the first embodiment. The bottom handle substrate  296  is then removed off the second passivation layer  290 . A second set of C4 balls  292  may be formed on an exposed second set of C4 pads as in the first and second embodiments. The first end portion and the second end portion of the conductive fin  302  are connected to a heat sink structure so that heat generated by semiconductor devices in the first and second semiconductor substrates ( 140 ,  240 ) are transferred through the middle portion, which is the embedded portion, of the conductive fin  302  through the first and second end portions of the conductive fin  302 , and then to the heat sink structure. 
       FIG. 32  shows a block diagram of an exemplary design flow  900  used for example, in semiconductor IC logic design, simulation, test, layout, and manufacture. Design flow  900  includes processes and mechanisms for processing design structures or devices to generate logically or otherwise functionally equivalent representations of the design structures and/or devices described above and shown in  FIGS. 1-31 . The design structures processes and/or generated by design flow  900  may be encoded on machine-readable transmission or storage media to include data and/or instructions that, when executed or otherwise processes on a data processing system, generate a logically, structurally, mechanically, or otherwise functionally equivalent representation of hardware components, circuits, devices, or systems. Design flow  900  may vary depending on the type of representation being designed. For example, a design flow for building an application specific integrated circuit (ASIC) may differ from a design flow  900  for designing a standard component or from a design flow  900  for instantiating the design into a programmable array, for example, a programmable gate array (PGA) or a field programmable gate array (FPGA) offered by Altera® Inc. or Xilinx® Inc. 
       FIG. 32  illustrates multiple such design structures including an input design structure  920  that is preferably processed by design process  910 . Design structure  920  may be a logical simulation design structure generated and processed by design process  910  to produce a logically equivalent functional representation of a hardware device. Design structure  920  may also, or alternately, comprise data and/or program instructions that, when processed by design process  910 , generate a functional representation of the physical structure of a hardware device. Whether representing functional and/or structural design features, design structure  920  may be generated using electronic computer-aided design (ECAD) such as implemented by a core developer/designer. When encoded on a machine-readable data transmission, gate array, or storage medium, design structure  920  may be accessed and processed by one or more hardware and/or software modules within design process  910  to simulate or otherwise functionally represent an electronic component, circuit, electronic or logic module, apparatus, device, or system such as those shown in  FIGS. 1-31 . As such, design structure  920  may comprise files or other data structures including human and/or machine-readable source code, compiled structures, and computer-executable code structures that when processed by a design or simulation data processing system, functionally simulate or otherwise represent circuits or other levels of hardware logic design. Such data structures may include hardware-description language (HDL) design entities or other data structures conforming to and/or compatible with lower-level HDL design languages such as Verilog and VHDL, and/or higher level design languages such as C or C++. 
     Design process  910  preferably employs and incorporates hardware and/or software modules for synthesizing, translating, or otherwise processing a design/simulation functional equivalent of the components, circuits, devices, or logic structures shown in  FIGS. 1-31  to generate a netlist  980  which may contain design structures such as design structure  920 . Netlist  980  may comprise, for example, compiled or otherwise processed data structures representing a list of wires, discrete components, logic gates, control circuits, I/O devices, models, etc. that describes the connections to other elements and circuits in an integrated circuit design. Netlist  980  may be synthesized using an iterative process in which netlist  980  is resynthesized one or more times depending on design specifications and parameters for the device. As with other design structure types described herein, netlist  980  may be recorded on a machine-readable data storage medium or programmed into a programmable gate array. The medium may be a non-volatile storage medium such as a magnetic or optical disk drive, a programmable gate array, a compact flash, or other flash memory. Additionally, or in the alternative, the medium may be a system or cache memory, buffer space, or electrically or optically conductive devices and materials on which data packets may be transmitted and intermediately stored via the Internet, or other networking suitable means. 
     Design process  910  may include hardware and software modules for processing a variety of input data structure types including netlist  980 . Such data structure types may reside, for example, within library elements  930  and include a set of commonly used elements, circuits, and devices, including models, layouts, and symbolic representations, for a given manufacturing technology (e.g., different technology nodes, 32 nm, 45 nm, 90 nm, etc.). The data structure types may further include design specifications  940 , characterization data  950 , verification data  960 , design rules  970 , and test data files  985  which may include input test patterns, output test results, and other testing information. Design process  910  may further include, for example, standard mechanical design processes such as stress analysis, thermal analysis, mechanical event simulation, process simulation for operations such as casting, molding, and die press forming, etc. One of ordinary skill in the art of mechanical design can appreciate the extent of possible mechanical design tools and applications used in design process  910  without deviating from the scope and spirit of the invention. Design process  910  may also include modules for performing standard circuit design processes such as timing analysis, verification, design rule checking, place and route operations, etc. 
     Design process  910  employs and incorporates logic and physical design tools such as HDL compilers and simulation model build tools to process design structure  920  together with some or all of the depicted supporting data structures along with any additional mechanical design or data (if applicable), to generate a second design structure  990 . Design structure  990  resides on a storage medium or programmable gate array in a data format used for the exchange of data of mechanical devices and structures (e.g. information stored in an IGES, DXF, Parasolid XT, JT, DRG, or any other suitable format for storing or rendering such mechanical design structures). Similar to design structure  920 , design structure  990  preferably comprises one or more files, data structures, or other computer-encoded data or instructions that reside on transmission or data storage media and that when processed by an ECAD system generate a logically or otherwise functionally equivalent form of one or more of the embodiments of the invention shown in  FIGS. 1-31 . In one embodiment, design structure  990  may comprise a compiled, executable HDL simulation model that functionally simulates the devices shown in  FIGS. 1-31 . 
     Design structure  990  may also employ a data format used for the exchange of layout data of integrated circuits and/or symbolic data format (e.g. information stored in a GDSII (GDS2), GL1, OASIS, map files, or any other suitable format for storing such design data structures). Design structure  990  may comprise information such as, for example, symbolic data, map files, test data files, design content files, manufacturing data, layout parameters, wires, levels of metal, vias, shapes, data for routing through the manufacturing line, and any other data required by a manufacturer or other designer/developer to produce a device or structure as described above and shown in  FIGS. 1-31 . Design structure  990  may then proceed to a stage  995  where, for example, design structure  990 : proceeds to tape-out, is released to manufacturing, is released to a mask house, is sent to another design house, is sent back to the customer, etc. 
     While the invention has been described in terms of specific embodiments, it is evident in view of the foregoing description that numerous alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, the invention is intended to encompass all such alternatives, modifications and variations which fall within the scope and spirit of the invention and the following claims.