Abstract: A substrate bonding apparatus for bonding a first substrate to a second substrate includes a first bonding chuck supporting the first substrate, a second bonding chuck disposed above the first bonding chuck and supporting the second substrate, a resonant frequency detector detecting a resonant frequency of a bonded structure with the first substrate and the second substrate which are at least partially bonded to each other, and a controller controlling a distance between the first bonding chuck and the second bonding chuck according to the detected resonant frequency of the bonded structure.

Abstract: A 3D semiconductor device including: a first level including a single crystal silicon layer and a plurality of first transistors each including a single crystal channel; a first metal layer overlaying the plurality of first transistors; a second metal layer overlaying the first metal layer; a third metal layer overlaying the second metal layer; a second level, where the second level overlays the first level and includes a plurality of second transistors; a fourth metal layer overlaying the second level; and a connective path between the fourth metal layer and either the third metal layer or the second metal layer, where the connective path includes a via disposed through the second level and has a diameter of less than 500 nm and greater than 5 nm, where the third metal layer is connected to provide a power or ground signal to at least one of the second transistors.

Abstract: A 3D semiconductor device, the device including: a first level including a plurality of first metal layers; a second level, where the second level overlays the first level, where the second level includes at least one single crystal silicon layer, where the second level includes a plurality of transistors, where each of the plurality of transistors includes a single crystal channel, where the second level includes a plurality of second metal layers, where the plurality of second metal layers include interconnections between the plurality of transistors, and where the second level is overlaid by a first isolation layer; and a connective path between the plurality of transistors and the plurality of first metal layers, where the connective path includes a via disposed through at least the single crystal silicon layer, and where the via has a diameter of less than 400 nm and greater than 5 nm.

Abstract: A method for manufacturing a semiconductor package includes following operations. A die having a first surface and a second surface opposite to the first surface is provided. A polymeric film is disposed over the second surface of the die. An adhesive film is provided. The die and the polymeric film are attached to a carrier substrate through the adhesive film. The die, the polymeric film and the adhesive film are molded with a molding compound. The polymeric film is sandwiched between the die and the adhesive film upon attaching to the carrier substrate.

Abstract: An apparatus for and a method of bonding a first substrate and a second substrate are provided. In an embodiment a first wafer chuck has a first curved surface and a second wafer chuck has a second curved surface. A first wafer is placed on the first wafer chuck and a second wafer is placed on a second wafer chuck, such that both the first wafer and the second wafer are pre-warped prior to bonding. Once the first wafer and the second wafer have been pre-warped, the first wafer and the second wafer are bonded together.

Abstract: The semiconductor manufacturing device includes: a lower substrate support base configured to support a diamond substrate; an upper substrate support base configured to support a semiconductor substrate; a support base drive unit configured to move the lower substrate support base and the upper substrate support base to bring the diamond substrate and the semiconductor substrate into close contact with each other under a state in which a pressure is applied to the diamond substrate and the semiconductor substrate in a thickness direction; and a second mechanism configured to deform a surface of the upper substrate support base opposed to the lower substrate support base so that a surface of the semiconductor substrate opposed to the diamond substrate forms a parallel surface or a parallel plane with respect to a surface of the diamond substrate opposed to the semiconductor substrate.

Abstract: In some embodiments, the present disclosure relates to a method for bonding a first wafer to a second wafer. The method includes aligning a first wafer with a second wafer, so the first and second wafers are vertically stacked and have substantially planar profiles extending laterally in parallel. The method further includes bringing the first and second wafers into direct contact with each other at an inter-wafer interface. The bringing of the first and second wafers into direct contact includes deforming the first wafer so that the first wafer has a curved profile and that the inter-wafer interface is localized to a center of the first wafer. The second wafer maintains its substantially planar profile throughout the deforming of the first wafer. The method further includes deforming the first wafer and/or the second wafer to gradually expand the inter-wafer interface from the center to an edge of the first wafer.

Abstract: A method and a device for bonding a first substrate with a second substrate at mutually facing contact faces of the substrates.

Abstract: Provided is a silicon wafer manufacturing method capable of reducing the warpage of the wafer occurring during a device process and allowing the subsequent processes, which have been suffered from problems due to severe warping of the wafer, to be carried out without problems and its manufacturing method. A silicon wafer manufacturing method according to the present invention is provided with calculating a target thickness of the silicon wafer required for ensuring a warpage reduction amount of a silicon wafer warped during a device process from a relationship between an amount of warpage of a silicon wafer and a thickness thereof occurring due to application of the same film stress to a plurality of silicon wafers having mutually different thicknesses; and processing a silicon single crystal ingot to thereby manufacture silicon wafers having the target thickness.

Abstract: Embodiments of methods and systems for wafer bonding alignment compensation are disclosed. The method comprises bonding a first pair of wafers including a first wafer and a second wafer, wherein the first pair of wafers have a plurality of corresponding bonding alignment mark pairs each including a first bonding alignment mark on the first wafer and a second bonding alignment mark on the second wafer; measuring alignment positions of the plurality of bonding alignment mark pairs; determining a mean run-out misalignment between the first pair of wafers using the alignment measurement, wherein the mean run-out misalignment indicates a deformation of at least one of the first pair of wafers; and during bonding of a second pair of wafers, controlling a wafer deformation adjustment module to compensate for the run-out misalignment based on the mean run-out misalignment of the first pair of wafers.

Abstract: A semiconductor package includes a die including a first surface and a second surface opposite to the first surface, a warpage control unit disposed over the second surface of the die and entirely overlapping the second surface of the die, and a molding compound surrounding the die and the warpage control unit. The warpage control unit includes an adhesive portion disposed over the second surface of the die and a warpage adjustable portion sandwiched between the adhesive portion and the die.

Abstract: A substrate bonding apparatus and a method of bonding substrates, the apparatus including an upper chuck securing a first substrate onto a lower surface thereof such that the first substrate is downwardly deformed into a concave surface profile; a lower chuck arranged under the upper chuck and securing a second substrate onto an upper surface thereof such that the second substrate is upwardly deformed into a convex surface profile; and a chuck controller controlling the upper chuck and the lower chuck to secure the first substrate and the second substrate, respectively, and generating a shape parameter for changing a shape of the second substrate to the convex surface profile from a flat surface profile.

Abstract: Techniques and mechanisms for forming a bond between wafers using a compliant layer. In an embodiment, a layer or layers of one or more compliant materials is provided on a first surface of a first wafer, and the one or more compliant layers are subsequently bonded to a second surface of a second wafer. The bonded wafers are heated to an elevated temperature at which a compliant layer exhibits non-elastic deformations to facilitate relaxation of stresses caused by wafer distortions. In another embodiment, a material of the compliant layer exhibits viscoelastic behavior at room temperature, wherein stress is mitigated by allowing wafer distortion to relax at room temperature.

Abstract: In various embodiments, a method for producing an optoelectronic device is provided. The method may include in the following order: providing a substrate, having a first state having a non-planar shape, reshaping the substrate into a second state. The second state has a planar or substantially planar shape. The method may further include forming at least one optoelectronic component on the substrate and reshaping the substrate into a third state. The third state is identical or substantially identical to the first state.

Abstract: Embodiments of methods and systems for adjusting wafer deformation during wafer bonding are provided. The method comprises: releasing inner rings of a first wafer, and applying a first gas pressure to the inner rings of the first wafer, such that the inner rings of the first wafer are in contact with a second wafer; releasing middle rings of the first wafer, such that the middle rings of the first wafer are deformed under a second gas pressure and in contact with the second wafer; releasing inner rings of the second wafer, and applying a third gas pressure less than the first gas pressure to the inner rings of the second wafer; releasing middle rings of the second wafer; and releasing outer rings of the first wafer and releasing outer rings of the second wafer simultaneously.

Abstract: A method for bonding a first substrate with a second substrate at respective contact faces of the substrates with the following steps: holding the first substrate to a first sample holder surface of a first sample holder with a holding force FH1 and holding the second substrate to a second sample holder surface of a second sample holder with a holding force FH2; contacting the contact faces at a bond initiation point and heating at least the second sample holder surface to a heating temperature TH; bonding of the first substrate with the second substrate along a bonding wave running from the bond initiation point to the side edges of the substrates, wherein the heating temperature TH is reduced at the second sample holder surface during the bonding.

Abstract: Provided are laminating apparatus and method. A laminating apparatus includes a jig assembly, which includes the first jig and an elastic member, and a second jig. A laminating method includes placing a first plate on a jig assembly, placing a second plate on a second jig which is placed to face the first jig, bringing the second plate into contact with the adhesive layer by making the jig assembly and the second jig approach each other, and, attaching the first plate and the second plate to each other by making the jig assembly and the second jig approach closer to each other. The jig assembly includes a first jig and an elastic member which comprises a top portion and sloping portions sloping downward from the top portion. An adhesive layer is disposed between the first plate and the second plate.

Abstract: In one embodiment there is disclosed a method for manufacturing an integrated circuit in a semiconductor substrate including through vias and a coplanar line, including the steps of: forming active components and a set of front metallization levels; simultaneously etching from the rear surface of the substrate a through via hole and a trench crossing the substrate through at least 50% of its height; coating with a conductive material the walls and the bottom of the hole and of the trench; and filling the hole and the trench with an insulating filling material; and forming a coplanar line extending on the rear surface of the substrate, in front of the trench and parallel thereto, so that the lateral conductors of the coplanar line are electrically connected to the conductive material coating the walls of the trench.

Abstract: A method includes forming a stress compensation layer over a first side of a semiconductor substrate and forming a Group III-nitride layer over a second side of the substrate. Stress created on the substrate by the Group III-nitride layer is at least partially reduced by stress created on the substrate by the stress compensation layer. Forming the stress compensation layer could include forming a stress compensation layer from amorphous or microcrystalline material. Also, the method could include crystallizing the amorphous or microcrystalline material during subsequent formation of one or more layers over the second side of the substrate. Crystallizing the amorphous or microcrystalline material could occur during subsequent formation of the Group III-nitride layer and/or during an annealing process. The amorphous or microcrystalline material could create no or a smaller amount of stress on the substrate, and the crystallized material could create a larger amount of stress on the substrate.

Abstract: To provide a resource-saving photoelectric conversion device with excellent photoelectric conversion characteristics. Thin part of a single crystal semiconductor substrate, typically a single crystal silicon substrate, is detached to structure a photoelectric conversion device using a thin single crystal semiconductor layer, which is the detached thin part of the single crystal semiconductor substrate. The thin part of the single crystal semiconductor substrate is detached by a method in which a substrate is irradiated with ions accelerated by voltage, or a method in which a substrate is irradiated with a laser beam which makes multiphoton absorption occur. A so-called tandem-type photoelectric conversion device is obtained by stacking a unit cell including a non-single-crystal semiconductor layer over the detached thin part of the single crystal semiconductor substrate.

Abstract: Methods and structures for GaN on silicon-containing substrates are disclosed, comprising a texturing process to generate a rough surface containing (111) surface, which then can act as an underlayer for epitaxial GaN. LED devices are then fabricated on the GaN layer. Variations of the present invention include different orientations of silicon layer instead of (100), such as (110) or others; and other semiconductor materials instead of GaN, such as other semiconductor materials suitable for LED devices.

Abstract: Provided is a composite substrate manufacturing method, including at least: a first raw board deforming step of preparing a first substrate by deforming a first raw board having at least one surface as a minor surface into a state in which the minor surface warps outward; and a joining step of joining, after the first raw board deforming step, a protruding surface of the first substrate and one surface of a second substrate to each other, thereby manufacturing a composite substrate including the first substrate and the second substrate, in which the second substrate is any one substrate selected from a substrate having both surfaces as substantially flat surfaces and a substrate that warps so that a surface thereof to be joined to the first substrate warps outward. Also provided are a semiconductor element manufacturing method, a composite substrate and a semiconductor element manufactured.

Abstract: A deformable focal plane array (DFPA) for imaging systems is disclosed. In one embodiment, the DFPA includes a detection circuitry on one side. For example, the thickness of the DFPA is in a range of about 5 to 40 microns. In one exemplary embodiment, the DFPA when warped to a desired shape provides a substantially wider field of view (FOV) than a flat focal plane array (FPA).

Abstract: A semiconductor device and a method for fabricating the semiconductor device. The device includes: a doped semiconductor having a source region, a drain region, a channel between the source and drain regions, and an extension region between the channel and each of the source and drain regions; a gate formed on the channel; and a screening coating on each of the extension regions. The screening coating includes: (i) an insulating layer that has a dielectric constant that is no greater than about half that of the extension regions and is formed directly on the extension regions, and (ii) a screening layer on the insulating layer, where the screening layer screens the dopant ionization potential in the extension regions to inhibit dopant deactivation.

Abstract: A method for bonding a first substrate having a first surface to a second substrate having a second surface. This method includes the steps of holding the first substrate by at least two support points, positioning the first substrate and the second substrate so that the first surface and the second surface face each other, deforming the first substrate by applying between at least one pressure point and the two support points a strain toward the second substrate, bringing the deformed first surface and the second surface into contact, and progressively releasing the strain to facilitate bonding of the substrates while minimizing or avoiding the trapping of air bubbles between the substrates.

Abstract: A multilayer substrate structure comprises a substrate, a thermal matching layer formed on the substrate and a lattice matching layer above the thermal matching layer. The thermal matching layer includes at least one of molybdenum, molybdenum-copper, mullite, sapphire, graphite, aluminum-oxynitrides, silicon, silicon carbide, zinc oxides, and rare earth oxides. The lattice matching layer includes a first chemical element and a second chemical element to form an alloy. The first and second chemical element has similar crystal structures and chemical properties. The coefficient of thermal expansion of the thermal matching layer and the lattice parameter of the lattice matching layer are both approximately equal to that of a member of group III-V compound semiconductors. The lattice constant of the lattice matching layer is approximately equal to that of a member of group III-V compound semiconductor.

Abstract: Room temperature IR and UV photodetectors are provided by electrochemical self-assembly of nanowires. The detectivity of such IR detectors is up to ten times better than the state of the art. Broad peaks are observed in the room temperature absorption spectra of 10-nm diameter nanowires of CdSe and ZnS at photon energies close to the bandgap energy, indicating that the detectors are frequency selective and preferably detect light of specific frequencies. Provided is a photodetector comprising: an aluminum substrate; a layer of insulator disposed on the aluminum substrate and comprising an array of columnar pores; a plurality of semiconductor nanowires disposed within the pores and standing vertically relative to the aluminum substrate; a layer of nickel disposed in operable communication with one or more of the semiconductor nanowires; and wire leads in operable communication with the aluminum substrate and the layer of nickel for connection with an electrical circuit.

Abstract: There is disclosed methods of making photosensitive devices, such as flexible photovoltaic (PV) devices, through the use of epitaxial liftoff. Also described herein are methods of preparing flexible PV devices comprising a structure having a growth substrate, wherein the selective etching of protective layers yields a smooth growth substrate that us suitable for reuse.

Abstract: A method for forming an electronic circuit on a strained semiconductor substrate, including the steps of: forming, on a first surface of a semiconductor substrate, electronic components defining electronic chips to be sawn; and forming at least portions of a layer of a porous semiconductor material on the side of a second surface of the semiconductor substrate, opposite to the first surface, to bend the semiconductor substrate.

Abstract: Systems, apparatuses, and methods related to the design, fabrication, and manufacture of gallium arsenide (GaAs) integrated circuits are disclosed. Copper can be used as the contact material for a GaAs integrated circuit. Metallization of the wafer and through-wafer vias can be achieved through copper plating processes disclosed herein. To avoid warpage, the tensile stress of a conductive layer deposited onto a GaAs substrate can be offset by depositing a compensating layer having negative stress over the GaAs substrate. GaAs integrated circuits can be singulated, packaged, and incorporated into various electronic devices.

Abstract: A semiconductor body comprised of a semiconductor material includes a first monocrystalline region of the semiconductor material having a first lattice constant along a reference direction, a second monocrystalline region of the semiconductor material having a second lattice constant, which is different than the first, along the reference direction, and a third, strained monocrystalline region between the first region and the second region.

Abstract: A method of fabricating a memory cell comprises forming a plurality of doped semiconductor layers on a carrier substrate. The method further comprises forming a plurality of digit lines separated by an insulating material. The digit lines are arrayed over the doped semiconductor layers. The method further comprises etching a plurality of trenches into the doped semiconductor layers. The method further comprises depositing an insulating material into the plurality of trenches to form a plurality of electrically isolated transistor pillars. The method further comprises bonding at least a portion of the structure formed on the carrier substrate to a host substrate. The method further comprises separating the carrier substrate from the host substrate.

Abstract: A method for alignment of a first substrate coupled to a second substrate includes determining an inclination angle for the first substrate or the second substrate due to warpage. The method includes determining a joint height difference based on the inclination angle and configuring a size for one or more bond pads based on the joint height difference.

Abstract: An electronic device manufacturing method includes a cutting step at which a wafer is cut to obtain chips before pattern formation and a polishing step at which cut surfaces of the obtained chips are subjected in one batch to barrel polishing. The method further includes an aligning step at which the polished chips are aligned so that front surfaces thereof face in an upward direction. The method further includes a bonding step at which the cut surfaces of the aligned chips are bonded together with an adhesive to thereby form a chip assembly. The method further includes a pattern forming step at which a circuit pattern is formed on each of the chips of the chip assembly and a melting step at which the adhesive on the chip assembly is melted to thereby separate the chip assembly into chips after pattern formation.

Abstract: A method is provided for preparing multilayer semiconductor structures, such as silicon-on-insulator wafers, having reduced warp and bow. Reduced warp multilayer semiconductor structures are prepared by forming a dielectric structure on the exterior surfaces of a bonded pair of a semiconductor device substrate and a semiconductor handle substrate having an intervening dielectric layer therein. Forming a dielectric layer on the exterior surfaces of the bonded pair offsets stresses that may occur within the bulk of the semiconductor handle substrate due to thermal mismatch between the semiconductor material and the intervening dielectric layer as the structure cools from process temperatures to room temperatures.

Abstract: At least one exemplary embodiment is directed to a method of forming a multilayered gettering structure that can be used to control wafer warpage.

Abstract: An integrated circuit chip is formed with an active layer and a trap rich layer. The active layer is formed with an active device layer and a metal interconnect layer. The trap rich layer is formed above the active layer. In some embodiments, the active layer is included in a semiconductor wafer, and the trap rich layer is included in a handle wafer.

Abstract: A method is disclosed which includes: forming at least one layer of material on at least part of a surface of a first substrate, wherein a first surface of the at least one layer of material is in contact with the first substrate thereby defining an interface; attaching a second substrate to a second surface of the at least one layer of material; forming bubbles at the interface; and applying mechanical force; whereby the second substrate and the at least one layer of material are jointly separated from the first substrate. Related arrangements are also described.

Abstract: Some embodiments discussed relates to an apparatus for holding a substrate, comprising a body with a surface for a semiconductor wafer to rest on, with the surface having a first surface area on which a first area of the semiconductor wafer can rest, and a second surface area on which a second area of the semiconductor wafer can rest, wherein the second surface area protrudes with respect to the first surface area.

Abstract: The invention pertains to a combination of a substrate and a wafer, wherein the substrate and the wafer are arranged parallel to one another and bonded together with the aid of an adhesive layer situated between the substrate and the wafer, and wherein the adhesive is chosen such that its adhesive properties are neutralized or at least diminished when a predetermined temperature is exceeded. According to the invention, the adhesive layer is only applied annularly between the substrate and the wafer in the edge region of the wafer.

Abstract: Aspects and examples include electrical components and methods of forming electrical components. In one example, a method includes selecting a substrate, forming a pattern of a first conductive material on a top surface of the substrate, forming a pattern of a second conductive material on a bottom surface of the substrate, dicing the substrate into one or more die having a first diced surface and a second diced surface, securing the first diced surface of each of the one or more die to a retaining material, encapsulating the one or more die in an encapsulent to form a reconstituted wafer, and forming a pattern of a third conductive material on the second diced surface by metalizing a surface of the reconstituted wafer.

Abstract: An anodic bonding apparatus includes a first electrode and a second electrode. The first electrode has a first surface, and the second electrode has a second surface facing the first surface. The first surface includes a first central area; a first substrate placing area for placing a laminated substrate; and a first peripheral area surrounding the first substrate placing area. The second surface includes a second central area corresponding to the first central area; a second substrate placing area surrounding the second central area; and a second peripheral area corresponding to the first peripheral area and surrounding the second substrate placing area. Further, the second electrode includes a curved portion curved toward the first electrode, so that a distance between the first central area and the second central area becomes smaller than a distance between the first peripheral area and the second peripheral area.

Abstract: Methods are provided for enhancing properties, including polarization, of thin-film ferroelectric materials in electronic devices. According to one embodiment, a process for enhancing properties of ferroelectric material in a device having completed wafer processing includes applying mechanical stress to the device, independently controlling the temperature of the device to cycle the temperature from room temperature to at or near the Curie temperature of the ferroelectric material and back to room temperature while the device is applied with the mechanical stress, and then removing the mechanical stress. Certain of the subject methods can be performed as part of a back end of line (BEOL) process, and may be performed during the testing phase at wafer or die level.

Abstract: A chip-to-wafer bonding method and a three-dimensional integrated semiconductor device are provided. The method comprises providing a chip and a wafer having a bonding region of the same size and shape as the chip; preparing hydrophilic areas and hydrophobic areas on the chip; preparing in the bonding region hydrophilic areas and hydrophobic areas respectively corresponding to the hydrophilic and hydrophobic areas on the chip; adding a liquid drop onto the hydrophilic areas in the bonding region; and pre-aligning and placing the chip on the bonding region of the wafer, such that the hydrophilic areas on the chip each contacts the corresponding hydrophilic area in the bonding region via the liquid. The sum of perimeters of the hydrophilic areas on the chip is larger than a perimeter of the chip. The sum of perimeters of the hydrophilic areas in the bonding region is larger than a perimeter of the bonding region.

Abstract: Provided is an organic EL apparatus including: an organic EL panel including organic EL devices; a heat releasing member; and a pair of film sheets of which at least one is transparent, wherein the organic EL panel and the heat releasing member overlap and are interposed and encapsulated by the pair of film sheets in a state where a portion of the heat releasing member is exposed outside the pair of film sheets.

Abstract: A method of processing an epistructure or processing a semiconductor device including associating a conformal and flexible handle with the epistructure and removing the epistructure and handle as a unit from the parent substrate. The method further includes causing the epistructure and handle unit to conform to a shape that differs from the shape the epistructure otherwise inherently assumes upon removal from the parent substrate. A device prepared according to the disclosed methods.

Abstract: A method is provided for bonding a semiconductor chip to a packaging substrate while minimizing the variation in the solder ball heights and controlling the stress in the solder balls and the stress in the packaging substrate. During the solder reflow, the warp of the packaging substrate, including the absolute warp, thermal warp, and substrate to substrate variations of the warp, is constrained at a minimal level by providing a clamping constraint to the packaging substrate. During cool down of the solder balls, the stresses and strains of the solder joints are maintained at levels that do not cause tear of the solder joints or breakage of the packaging substrate by removing the clamping constraint. Thus, the bonding process provides both uniform solder height with minimized solder non-wets and stress minimization of the solder balls and the packaging substrate.

Abstract: A composite-substrate manufacturing method is provided with: a step of carrying out implantation of ions through a surface of a bulk substrate composed of the nitride compound semiconductor; a step of setting said surface of the bulk substrate against the second substrate, and bonding the bulk substrate and the second substrate together to obtain a bonded substrate; a step of elevating the temperature of the bonded substrate to a first temperature; a step of sustaining the first temperature for a fixed time; and a step of producing a composite substrate by severing the remaining portion of the bulk substrate from the bonded substrate; characterized in that a predetermined formula as for the first temperature, the thermal expansion coefficient of the first substrate, and the thermal expansion coefficient of the second substrate is satisfied.

Abstract: A semiconductor device includes a first wafer having at least one first integrated-circuit chip and a first support layer surrounding the first integrated circuit chip. A first electrical-connection layer is placed on a frontside of the first wafer and includes a first electrical-connection network. A second wafer is placed on a frontside of the first electrical-connection layer. The second wafer includes at least one second integrated-circuit chip and a second support layer surrounding the second integrate circuit chip. The second integrated circuit chip has an active side facing the first electrical-connection layer, and one or more through-holes filled with a conductor forming electrical-connection vias. A second electrical-connection layer is placed on the backside of the second wafer and includes a second electrical-connection network.

Abstract: A method for the direct bonding of a first wafer having an intrinsic curvature before bonding to a second wafer having an intrinsic curvature before bonding, at least one of the two wafers including at least one series of microcomponents. The method includes bringing the two wafers into contact with each other so as to initiate the propagation of a bonding wave therebetween while imposing a predefined bonding curvature in the form of a paraboloid of revolution on one of the two wafers depending at least upon the intrinsic curvature before bonding of the wafer that includes the microcomponents, with the other wafer being free to conform to the predefined bonding curvature.