Three-dimensional multi-point compression bonding arm for advanced integration

Abstract

Aspects of the present disclosure provide a bonding apparatus for bonding two wafers. For example, a bonding apparatus may include a first bonding chuck and a second bonding chuck. The first bond chuck may have a first bond head for mounting a first wafer thereon. The second bond chuck may have a plurality of second bond heads for mounting a second wafer thereon. The second bond head may be individually controlled to apply a local pressure to the second wafer to move the second wafer toward the first wafer to bond the second wafer to the first wafer, the local pressure corresponding to bending measurements of the first wafer and the second wafer.

Description

[0001] Cross - Reference to Related Applications

[0002] This application claims the benefit of U.S. Non - Provisional Application No. 18 / 081,207, filed on December 14, 2022, which is hereby incorporated by reference in its entirety. Technical Field

[0003] This disclosure relates to semiconductor manufacturing, and more particularly to wafer bending, wafer - to - wafer bonding, and wafer - to - die bonding. Background Art

[0004] The background art description provided herein is for the purpose of generally presenting the background of the disclosure. To the extent that the work of the current inventors is described in this background art section and aspects of this description that may not be prior art at the time of filing are neither expressly nor implicitly admitted to be prior art to the disclosure.

[0005] Semiconductor manufacturing involves a number of different steps and processes. A typical manufacturing process is called lithography (also known as microlithography). Lithography uses radiation such as ultraviolet or visible light to generate fine patterns in semiconductor device designs. Many types of semiconductor devices such as diodes, transistors, and integrated circuits can be constructed using semiconductor manufacturing techniques including lithography, etching, film deposition, surface cleaning, metallization, and so on.

[0006] Exposure systems (also known as tools) are used to implement lithography techniques. An exposure system typically includes an illumination system, a mask (also known as a photomask) or a spatial light modulator (SLM) for generating a circuit pattern, a projection system, and a wafer alignment stage for aligning a semiconductor wafer covered with a photosensitive resist. The illumination system illuminates an area of the mask or SLM with a (preferably) rectangular slit illumination field. The projection system projects an image of the illuminated area of the mask pattern onto the wafer. For accurate projection, it is important to expose the light pattern on a relatively flat or planar (preferably, height deviation less than 10 microns) wafer. Bonding of two or more semiconductor wafers and / or dies provides higher performance for high - density semiconductor devices. Summary of the Invention

[0007] Aspects of the present disclosure provide a system for bonding two wafers. For example, the system may include a bend measurement device, a bonding device, and a controller. The bend measurement device may be configured to measure a first wafer and a second wafer to identify bend measurement results of the first wafer and the second wafer. The bonding device may be configured to bond the first wafer to the second wafer. The controller may be coupled to the bend measurement device and the bonding device and be configured to control the bonding device to apply pressure to the first wafer and the second wafer based on the bend measurement results to bond the first wafer to the second wafer. In an embodiment, the second wafer is a die.

[0008] In an embodiment, the system may further include a film forming device coupled to the controller, the film forming device being configured to form a bonding film on a first surface of a first wafer and a second wafer. For example, the system may further include a heat generator coupled to the controller, the heat generator being configured to generate a heat pattern, wherein the film forming device is further configured to form a first stress modifying film and a second stress modifying film on second surfaces of the first wafer and the second wafer respectively, the first stress modifying film and the second stress modifying film being responsive to heat such that the applied heat modifies internal stresses of the first stress modifying film and the second stress modifying film, the bending measurement device being further configured to measure the first wafer and the second wafer when the first stress modifying film and the second stress modifying film are respectively formed on the second surfaces of the first wafer and the second wafer and the internal stresses of the first stress modifying film and the second stress modifying film have been modified, to identify bending measurement results of the first wafer and the second wafer, the bending measurement device being further configured to measure the first wafer and the second wafer when no stress modifying film is formed on the second surfaces of the first wafer and the second wafer, to identify another bending measurement result of the first wafer and the second wafer, and the controller being further configured to control the heat generator to generate a heat pattern and apply the heat pattern to the first stress modifying film and the second stress modifying film, the heat pattern corresponding to the another bending measurement result. As another example, the system may further include a light generator coupled to the controller, the light generator being configured to generate a pattern of light of a first wavelength and a second wavelength, wherein the film forming device is further configured to form a first stress modifying film and a second stress modifying film on second surfaces of the first wafer and the second wafer respectively, the first stress modifying film and the second stress modifying film being responsive to light of the first wavelength and light of the second wavelength respectively such that exposure to light of the first wavelength and light of the second wavelength respectively modifies internal stresses of the first stress modifying film and the second stress modifying film, the bending measurement device being further configured to measure the first wafer and the second wafer when the first stress modifying film and the second stress modifying film are respectively formed on the second surfaces of the first wafer and the second wafer and the internal stresses of the first stress modifying film and the second stress modifying film have been modified, to identify bending measurement results of the first wafer and the second wafer, the bending measurement device being further configured to measure the first wafer and the second wafer when no stress modifying film is formed on the second surfaces of the first wafer and the second wafer, to identify another bending measurement result of the first wafer and the second wafer, and the controller being further configured to control the light generator to generate a pattern of light of the first wavelength and the second wavelength and apply the pattern of light of the first wavelength and the second wavelength to the first stress modifying film and the second stress modifying film respectively, the pattern of light of the first wavelength and the second wavelength corresponding to the another bending measurement result.

[0009] Aspects of the present disclosure provide a method for bonding two wafers. For example, the method may include: receiving a first wafer and a second wafer; measuring the first wafer and the second wafer to identify bending measurements of the first wafer and the second wafer; and applying pressure to a second surface of the first wafer and the second wafer based on the bending measurements of the first wafer and the second wafer to bond the first wafer to the second wafer.

[0010] In an embodiment, the method may further include forming a bonding film on a first surface of the first wafer. For example, the method may further include: measuring the first wafer in the absence of any stress modifying film on a second surface of the first wafer to identify another bending measurement of the first wafer; forming a stress modifying film on the second surface of the first wafer, the stress modifying film being responsive to heat such that applied heat modifies an internal stress of the stress modifying film; and applying a heat pattern to the stress modifying film to modify the internal stress of the stress modifying film, the heat pattern corresponding to the another bending measurement, wherein measuring the first wafer and the second wafer to identify bending measurements of the first wafer and the second wafer includes measuring the first wafer and the second wafer in the presence of a stress modifying film on the second surface of the first wafer and with the internal stress of the stress modifying film modified to identify bending measurements of the first wafer and the second wafer. As another embodiment, the method may further include: measuring the first wafer in the absence of any stress modifying film on a second surface of the first wafer to identify another bending measurement of the first wafer; forming a stress modifying film on the second surface of the first wafer, the stress modifying film being responsive to light of a certain wavelength such that exposure to the wavelength of light modifies an internal stress of the stress modifying film; and applying a pattern of light of the certain wavelength to the stress modifying film to modify the internal stress of the stress modifying film, the pattern of light of the certain wavelength corresponding to the another bending measurement, wherein measuring the first wafer and the second wafer to identify bending measurements of the first wafer and the second wafer includes measuring the first wafer and the second wafer in the presence of a stress modifying film on the second surface of the first wafer and with the internal stress of the stress modifying film modified to identify bending measurements of the first wafer and the second wafer.

[0011] In an embodiment, the method may further include: measuring another die to identify another bending measurement of the another die; and applying another pressure to a first surface of the another die based on the another bending measurement to bond the another die to the die. In another embodiment, the method may further include: measuring another die to identify another bending measurement of the another die; and applying another pressure to a first surface of the another die based on the another bending measurement to bond the another die to the second wafer.

[0012] Aspects of the present disclosure provide a bonding apparatus for bonding two wafers. For example, the bonding apparatus may include a first bonding chuck and a second bonding chuck. The first bonding chuck may have a first bonding head for mounting a first wafer thereon. The second bonding chuck may have a plurality of second bonding heads for mounting a second wafer thereon. The second bonding heads may be configured to be individually controlled to apply local pressure to the second wafer to move the second wafer towards the first wafer so as to bond the second wafer to the first wafer, the local pressure corresponding to the bending measurements of the first wafer and the second wafer.

[0013] In an embodiment, the first bonding head may apply a global pressure to the first wafer to move the first wafer towards the second wafer so as to bond the first wafer to the second wafer. In another embodiment, the first bonding chuck may further include one or more heating units disposed in the first bonding head, the heating units being configured to provide heat to cure a bonding film for bonding the first wafer to the second wafer.

[0014] In an embodiment, the second wafer may be a die, and the second bonding heads may be arranged in a manner matching the die size. In another embodiment, the first of the second bonding heads may be in a first shape, and the second of the second bonding heads may be in a second shape different from the first shape. For example, the first shape may be circular, rectangular, or crescent-shaped.

[0015] Note that the present summary section does not specify every embodiment and / or incremental novel aspect of the present disclosure or the claimed invention. Rather, the present summary only provides a preliminary discussion of different embodiments and corresponding novel points that are superior to conventional techniques. For additional details and / or possible perspectives of the present disclosure and embodiments, the reader should refer to the detailed description section of the present disclosure and the corresponding drawings discussed further below. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The different embodiments of the present disclosure presented as examples will be described in detail with reference to the following drawings, in which like reference numerals refer to like elements, and in which:

[0017] Figures 1A to 1C The first-order bending and second-order bending of a wafer are shown.

[0018] Figure 2 is a functional block diagram of an exemplary system for bonding two wafers and / or dies according to some embodiments of the present disclosure;

[0019] Figure 3 is shown by Figure 2 the exemplary heat pattern generated by the heat generator of the exemplary system shown;

[0020] Figure 4 is a schematic diagram of a first exemplary bonding device according to some embodiments of the present disclosure;

[0021] Figure 5 shows according to some embodiments of the present disclosure Figure 4 the shape of the top bonding head of the bonding device;

[0022] Figure 6 is a flowchart showing a first exemplary method (or process flow) of bonding two wafers by using a bonding device according to some embodiments of the present disclosure;

[0023] Figure 7 is a schematic diagram of a second exemplary bonding device according to some embodiments of the present disclosure;

[0024] Figure 8 is a flowchart showing a second exemplary method (or process flow) of bonding two wafers by using a bonding device according to some embodiments of the present disclosure; and

[0025] Figure 9 is a flowchart showing a third exemplary method (or process flow) of bonding two wafers by using a bonding device according to some embodiments of the present disclosure. DETAILED DESCRIPTION

[0026] To obtain the best resolution when using a mask with a laser or EMSλ (electromagnetic spectrum wavelength) sensitive photoresist to define the areas that are blocked or opened for subsequent pattern transfer or implantation, it is necessary to have the best shape of the wafer surface before the light / lithography process. The techniques disclosed herein include stress modulation of the film on the wafer to achieve the target curvature or correction. The techniques herein can use all types of light-sensitive wavelengths / lithography types in the electromagnetic spectrum (some examples are lithography, electron beam lithography, direct laser writing, and x-ray lithography). The techniques disclosed herein also include applying local pressure to two wafers based on the bending measurements of the two wafers to bond them to each other such that the two wafers so bonded have the best wafer shape.

[0027] The techniques disclosed herein define several process flows (using semiconductor stress film tuning or tuning its lattice) to obtain the best starting wafer shape before using a light process on the working surface of the wafer. As an option, the process flows herein include a one-time stress tuning film on the backside surface of the wafer. Another option is to leave the stress tuning film in place for subsequent processing, for some cases where several steps of low-temperature processing can be performed.

[0028] By using a photoresist film that can be patterned with a mask or directly written with photolithographic stress film features. A unique aspect of the present disclosure is that, due to the sensitivity of the photoresist emulsion to a certain laser or EM wavelength, the deposited photoresist film can be in compressive stress, tensile stress, or neutral stress under deposition conditions. Thus, micro-stress regions can be defined by masking and etching the deposited film, or by direct writing regions (or direct writing options) in cases where selective compressive / neutral / tensile regions are desired. The process can also be replicated with two different depositions (i.e., one sensitive to a first laser wavelength and the other to a second laser wavelength) to eliminate wafer bending after laser processing.

[0029] The techniques herein include wafer stress modification techniques for modifying wafer bending and curvature to improve wafer overlay accuracy. For all processes with wafer clamping options, stress film deposition can be performed for all process flows either with the wafer surface facing up or down. The techniques herein also include bonding two wafers by applying local pressure based on the bending measurements of the two wafers.

[0030] The microfabrication of the semiconductor structure 100 begins with a flat substrate or wafer 110, such as Figures 1A to 1C those shown. During the microfabrication of the semiconductor structure 100, multiple processing steps are performed, which may include depositing materials, removing materials, implanting dopants, annealing, baking, etc. on the wafer 110. The resulting different material and structural forms 120 may induce internal stress in the wafer 110, which causes the semiconductor structure 100 to bend, thereby affecting overlay accuracy and typically resulting in overlay errors of various magnitudes. For example, Figure 1A and Figure 1B respectively illustrate how different material and structural forms 120 can induce compressive stress or tensile stress in the wafer 110, resulting in first-order bending, where the bending measurement shows the deviation of the z-direction height from a reference plane (not shown). As another example, Figure 1C illustrates the second-order bending of the wafer 110, where two bending measurements respectively identify the positive z-direction height deviation and the negative z-direction height deviation.

[0031] If some regions of two wafers among the wafers 110 to be bonded to each other contain compressive stress or tensile stress, multiple pressure heads can be used to enable more effective bonding processes with local pressure, and thus improve die yield in the case of the best wafer shape. In each of the local nano-stress regions, the opposite type of stress can be applied. By modifying the internal stress of the stress modification film using a thermal / optical zone or position array on the wafer chuck, the best wafer shape can be achieved quickly and at the lowest cost.

[0032] Figure 2 is a functional block diagram of an exemplary system 200 for bonding two or more wafers and / or dies in accordance with some embodiments of the present disclosure. For example, system 200 may include metrology equipment (e.g., bend measurement device 210), which is configured to measure a substrate, die, or wafer (e.g., Figures 1A to 1C wafer 110 as shown) to identify bend measurement results of wafer 110. In an embodiment, bend measurement device 210 may use optical (e.g., using scanning laser technology), acoustic, and other mechanisms to measure z-direction height deviations on the surface of wafer 110 and store the height deviations by (x, y) coordinates in order to identify multiple sub-bend measurement results (x, y) in the bend measurement results. The z-direction height deviations may be mapped at various resolutions and / or desired resolutions depending on the type of metrology equipment used. The bend measurement results (and sub-bend measurement results) may include raw bend data or be represented as bend features with relative values. In an embodiment, wafer 110 has a working surface 110A and a backside surface 110B opposite the working surface 110A, on which different material and structural forms 120 may be formed, as Figure 1A shown. Since one or more microfabrication processing steps have been performed to create at least a portion of a semiconductor structure (e.g., semiconductor structure 100) on the working surface 110A of wafer 110, wafer 110 may have a certain amount of wafer bend. For example, a transistor gate may be complete or only partially complete.

[0033] System 200 may further include a deposition module (e.g., film-forming device 220), which is configured to deposit and form films (e.g., stress modification films and bonding films) on the backside surface 110B and / or working surface 110A of wafer 110 and / or die. For example, film-forming device 220 may deposit a stress modification film and a bonding film on the backside surface 110B and working surface 110A of wafer 110 respectively by spin coating, lamination, spraying, or other suitable deposition techniques. When the stress modification film is exposed to heat / light and reacts to heat / light, the internal stress of the stress modification film may be modified by heat / light. Film-forming device 220 may be configured to form two or more stress modification films with different (e.g., opposite) stresses. The bonding film may bond wafers and dies to each other.

[0034] System 200 may further include a heat / light generator 230, which is configured to generate a heat / light pattern 300, as Figure 3As shown. In an embodiment, the thermal / optical generator 230 can generate a laser (e.g., direct laser writing) and light of multiple wavelengths. In another embodiment, the thermal / optical generator 230 can include a plurality of heating / illuminating units, which can be mounted on the wafer chuck and have an arrangement corresponding to the thermal / optical pattern 300. For example, the thermal / optical generator 230 can include heating / illuminating units (3, 1) to (6, 1), (2, 2) to (7, 2), (1, 3) to (8, 3), (1, 4) to (8, 4), (1, 5) to (8, 5), (1, 6) to (8, 6), (2, 7) to (7, 7), and (3, 8) to (6, 8), a total of 52 heating / illuminating units, and the bending measurement device 210 can measure the wafer 110 to identify the bending measurement result of the wafer 110, which includes corresponding sub-bending measurement results (3, 1) to (6, 1), (2, 2) to (7, 2), (1, 3) to (8, 3), (1, 4) to (8, 4), (1, 5) to (8, 5), (1, 6) to (8, 6), (2, 7) to (7, 7), and (3, 8) to (6, 8). The (Poseidon) thermal / optical micro-pattern 300 herein can eliminate warping, such that high-resolution lithographic patterning can be maintained in all process steps of 3D stacking.

[0035] The thermal / optical generator (or thermal generator) 230 can generate heat in multiple temperature ranges. For example, the thermal generator 230 can generate heat in a first temperature range up to 200 °C, heat in a second temperature range between 200 °C and 500 °C, heat in a third temperature range between 500 °C and 800 °C, and heat in a fourth temperature range above 800 °C.

[0036] Return to Figure 2 , the system 200 can further include a bonding device 240, which is configured to apply pressure to two wafers and / or dies (at least one of the surfaces (e.g., working surfaces) of the two wafers and / or dies has a bonding film formed thereon) to bond the two wafers and / or dies to each other.

[0037] System 200 may further include a controller 250, which is coupled to the bending measurement device 210, the film forming device 220, the heat / light generator 230, and the bonding device 240. The controller 250 may be configured to: control the bending measurement device 210 to measure the wafer (and / or die) 110 to identify the bending measurement results (and sub-bending measurement results) of the wafer 110; control the film forming device 220 to form a stress modification film and / or a bonding film on the back surface 110B and / or the working surface 110A of the wafer 110; control the heat / light generator 230 to generate a heat / light pattern 300 and apply the heat / light pattern to the stress modification film, the heat / light pattern corresponding to the bending measurement results (and sub-bending measurement results); and control the bonding device 240 to bond two wafers 110 to each other. The controller 250 may be a computer processor located within the system 200 or a computer processor that is remotely located but communicates with the components of the system 200.

[0038] System 200 may further include other components, such as a wafer chuck for placing the wafer thereon, a robotic arm configured to flip the wafer 110 and transfer the wafer between various devices and / or chambers, a wafer gripper configured to hold the wafer 110, a coating device configured to coat the back surface 110B of the wafer 110 with a radiation-sensitive material (such as photoresist), a baking device configured to bake the photoresist, an imaging device configured to expose the photoresist to a photochemical radiation pattern, a developing device configured to develop a latent image in the photoresist, and an etching device configured to use plasma or vapor etching or wet etching.

[0039] Figure 4 is a schematic diagram of an exemplary bonding device 400 (e.g., the bonding device 240 of the system 200) according to some embodiments of the present disclosure. In an embodiment, the bonding device 400 may include a bottom (or first) bonding chuck 410 and a top (or second) bonding chuck 420, which are controlled by a controller (e.g., the controller 250) to move towards and away from each other and apply pressure to a first wafer 430 and a second wafer 440 (e.g., the wafer 110), at least one of the first wafer and the second wafer having a bonding film 450 formed on its surface (e.g., the working surface 110A), to bond the first wafer 430 and the second wafer 440 to each other. In an embodiment, the bonding film 450 may be insulating and include an epoxy resin, a metal, or a combination thereof.

[0040] In an embodiment, the bottom bonding chuck 410 may include a bottom bonding (or pressing) head 411 (e.g., circular) for mounting the first wafer 430 thereon. The bottom bonding head 411 may apply a global pressure (i.e., force / first wafer area) to the first wafer 430. The bottom bonding chuck 410 may further include one or more holes or perforations (not shown) formed in its mounting surface 410A. A vacuum system may be coupled to the bottom bonding chuck 410 and transmit a negative pressure to the first wafer 430 through the holes or perforations to hold the first wafer 430 in place during a subsequent bonding process.

[0041] In an embodiment, the top bonding chuck 420 may include a plurality of top bonding (or pressing) heads 421 for mounting the second wafer 440 thereon. For example, the top bonding heads 421 may be arranged, for example, in a manner corresponding to the thermal / optical pattern 300 and individually controlled by the controller 250 based on the bending measurement results of the second wafer 440 to apply a local pressure to the second wafer 440. The top bonding chuck 420 may also include one or more holes or perforations (not shown) formed in its mounting surface 420A. A vacuum system may be coupled to the top bonding chuck 420 and transmit a negative pressure to the second wafer 440 through the holes or perforations to hold the second wafer 440 in place during a subsequent bonding process. The top bonding heads 421 may be of various shapes. For example, as Figure 5 shown, the bonding device 500 may include a first group 521A of rectangular (e.g., square) top bonding heads 421, a second group 521B of circular top bonding heads 421, and a third group 521C of crescent-shaped top bonding heads 421. In some embodiments, the thermal / optical generator 230 may include one or more groups of heating / illuminating units having different shapes.

[0042] Figure 6 FIG. shows a flowchart of an exemplary method (or process flow) 600 for bonding two wafers using a bonding device according to some embodiments of the present disclosure. In different embodiments, some steps of the illustrated method 600 may be performed simultaneously or in a different order than shown, may be replaced by other method steps, or may be omitted. Additional method steps may also be performed as needed. Aspects of the method 600 may be implemented by a system (such as the system 200 shown and described with respect to the previous figures).

[0043] In step S610, the curvatures / bendings of the first wafer 430 and the second wafer 440 to be bonded to each other are measured. For example, the bending measurement device 210 may be used to measure the first wafer 430 and the second wafer 440 to identify the bending measurement results of the first wafer 430 and the second wafer 440.

[0044] In step S620, optionally, a stress modification film 610 may be formed on the backside surfaces of the first wafer 430 and the second wafer 440 and the stress modification film may be exposed to heat / light so that the internal stress of the stress modification film is modified by the heat / light, thereby modifying the curvature / bending of the first wafer 430 and the second wafer 440. For example, a film forming apparatus 220 may be used to deposit and form the stress modification film 610 on the backside surfaces of the first wafer 430 and the second wafer 440, and a heat / light generator 230 may be used to generate a heat / light pattern based on the bending measurement results of the first wafer 430 and the wafer 440 to modify the internal stress of the stress modification film 610. Then, method 600 may return to step S610 to measure the curvature / bending of the first wafer and the second wafer with the stress modification film 610 formed on the backside surfaces of the first wafer 430 and the second wafer 440.

[0045] In step S630 after step S610 or step S620, a bonding film (e.g., bonding film 450) may be formed on the working surface of at least one of the first wafer 430 and the second wafer 440. In an exemplary embodiment, a first bonding film 651 and a second bonding film 652 may be respectively formed on the working surfaces of the first wafer 430 and the second wafer 440. For example, a film forming apparatus 220 may be used to sequentially deposit and form the first bonding film 651 on the working surface of the first wafer 430 and deposit and form the second bonding film 652 on the working surface of the second wafer 440.

[0046] In step S640, the first wafer 430 (on whose working surface the first bonding film 651 is formed) is mounted on the bottom bonding head 411 of the bottom bonding chuck 410. Then, the vacuum system may be turned on to transfer negative pressure to the first wafer 430 through the holes or perforations in the mounting surface 410A ( Figure 4 as shown) so as to hold the first wafer 430 in place during subsequent bonding processes.

[0047] In step S650, the second wafer 440 (on whose working surface the second bonding film 652 is formed) is mounted on the top bonding head 421 of the top bonding chuck 420. The vacuum system may transfer negative pressure to the second wafer 440 through the holes or perforations in the mounting surface 420A ( Figure 4 as shown) so as to hold the second wafer 440 in place during subsequent bonding processes. In an embodiment, steps S640 and S650 may be performed in a different order.

[0048] In step S660, the first wafer 430 and the second wafer 440 are bonded to each other. For example, the controller 250 can control the bottom bonding chuck 410 and the top bonding chuck 420 to align and move towards each other until the first bonding film 651 contacts the second bonding film 652, and control the bottom bonding head 411 to apply a global pressure to the first wafer 430 and control the top bonding head 421 to apply a local pressure to the second wafer 440 based on the bending measurement result of the second wafer 440, so as to bond the second bonding film 652 to the first bonding film 651 and thus bond the second wafer 440 to the first wafer 430. In an embodiment, the bonding technique of the first bonding film 651 and the second bonding film 652 may include direct bonding, anodic bonding, adhesive bonding, welding bonding, eutectic bonding, etc.

[0049] In step S670, the bonded first wafer 430 and second wafer 440 are removed from the bottom bonding chuck 410 and the second bonding chuck 420 respectively for subsequent processing options (e.g., dicing into dies). For example, the vacuum system can be turned off, and the bonded first wafer 430 and second wafer 440 can be released from the holding of the bottom bonding chuck 410 and the second bonding chuck 420 respectively. Thus, the bonded first wafer 430 and second wafer 440 have an optimal wafer shape.

[0050] Figure 7 is a schematic diagram of an exemplary bonding device 700 (e.g., the bonding device 240 of the system 200) according to some embodiments of the present disclosure. The bonding device 700 may include a top bonding chuck 420 and a bottom bonding chuck 710. Compared with Figure 4 the bottom bonding chuck 410 of the bonding device 400 shown, the bottom bonding chuck 710 of the bonding device 700 further includes one or more heating units 721, which are disposed in the bottom bonding head 411 and are controlled by the controller 250 to provide heat for curing the bonding film 450.

[0051] Figure 8A flowchart of an exemplary method (or process flow) 800 for bonding two wafers by using a bonding device (e.g., bonding device 700) in accordance with some embodiments of the present disclosure is shown. Aspects of method 800 may be implemented by a system (such as system 200 shown and described with respect to the previous figures). Method 800 may also include steps S610 to S650 and S670 of method 600. In an embodiment, the method may further include step S760 performed between steps S650 and S670. At step S760, the first wafer 430 and the second wafer 440 are bonded to each other. For example, the controller 250 may control the bottom bonding chuck 710 and the top bonding chuck 420 to align and move towards each other until the first bonding film 651 contacts the second bonding film 652, control the bottom bonding head 411 to apply a global pressure to the first wafer 430 and control the top bonding head 421 to apply a local pressure to the second wafer 440 based on the bending measurement result of the second wafer 440, and control the heating unit 721 to provide heat to cure the first bonding film 651 and the second bonding film 652 to bond the second bonding film 652 to the first bonding film 651 and thus bond the second wafer 440 to the first wafer 430.

[0052] Figure 9 A flowchart of an exemplary method (or process flow) 900 for bonding a plurality of dies to a wafer by using a bonding device in accordance with some embodiments of the present disclosure is shown. Aspects of method 900 may be implemented by a system (such as system 200 shown and described with respect to the previous figures). Method 900 is different from method 800 in that, in method 900, the top bonding chuck 920 and the plurality of dies 940 replace Figure 8 the top bonding chuck 420 and the second wafer 440 used in the method 800 shown.

[0053] At step S910, the curvature / bending of the first wafer 430 and the die 940 to be bonded to each other is measured. For example, the bending measurement device 210 may be used to measure the first wafer 430 and each die 940 to identify the bending measurement results of the first wafer 430 and the die 940.

[0054] In step S920, optionally, a stress modification film 610 and a stress modification film 910 may be formed on the back surfaces of the first wafer 430 and the die 940 and these stress modification films may be exposed to heat / light so that the internal stress of these stress modification films is modified by the heat / light, thereby modifying the curvature / bending of the first wafer 430 and the die 940. For example, a film forming apparatus 220 may be used to deposit and form the stress modification films 610 and 910 on the back surfaces of the first wafer 430 and the die 940 respectively, and a heat / light generator 230 may be used to generate a heat / light pattern based on the bending measurement results of the first wafer 430 and each die 440 to modify the internal stress of the stress modification films 610 and 910. Then, method 900 may return to step S910 to measure the curvature / bending of the first wafer and the die with the stress modification films 610 and 910 formed on the back surfaces of the first wafer 430 and the die 940.

[0055] In step S930, which is after step S910 or step S920, a bonding film (e.g., bonding film 450) may be formed on the working surface of the first wafer 430 and / or the die 940. In an exemplary embodiment, a first bonding film 651 and a second bonding film 952 may be formed on the working surfaces of the first wafer 430 and the die 940 respectively. For example, a film forming apparatus 220 may be used to deposit and form the first bonding film 651 on the working surface of the first wafer 430 in sequence and deposit and form the second bonding film 952 on the working surface of the die 940.

[0056] In step S940, the first wafer 430 (on whose working surface the first bonding film 651 is formed) is mounted on the bottom bonding head 411 of the bottom bonding chuck 710 (or bottom bonding chuck 410). Then, the vacuum system may be turned on to transmit a negative pressure to the first wafer 430 through the holes or perforations in the mounting surface 410A ( Figure 4 as shown) so as to hold the first wafer 430 in place during the subsequent bonding process.

[0057] In step S950, the die 940 (on whose working surface a second bonding film 952 is formed) is mounted one by one onto the top bonding head 921 of the top bonding chuck 920. In an embodiment, the top bonding head 921 may be arranged, for example, in a manner corresponding to the thermal / optical pattern 300 and is individually controlled by the controller 250 based on the bending measurement results of the die 440. The top bonding chuck 920 may also include one or more holes or perforations (not shown) formed in its mounting surface 920A. A vacuum system may be coupled to the top bonding chuck 920 and transmit a negative pressure to each die 940 through the holes or perforations to hold the die 940 in place during subsequent bonding processes. The top bonding head 921 may be in various shapes. In step S950, the vacuum system may be turned on and a negative pressure may be transmitted to the die 940 through the holes or perforations in the mounting surface 920A, thereby holding the die 940 in place during subsequent bonding processes. In an embodiment, steps S940 and S950 may be performed in a different order.

[0058] In step S960, one of the first wafer 430 and the die 940 is bonded to each other. For example, the controller 250 may control the bottom bonding chuck 410 and the top bonding chuck 920 to align and move towards each other until the first bonding film 651 contacts the second bonding film 952, and control the bottom bonding head 411 to apply a global pressure to the first wafer 430 and control the top bonding head 921 to apply a local pressure to the die 940 based on the bending measurement results of the die 940, so as to bond the second bonding film 952 to the first bonding film 651 and thus bond the die 940 to the first wafer 430.

[0059] In step S970, the die 940 is removed from the top bonding chuck 920 for subsequent processing options (such as bonding another die). For example, the vacuum system may be turned off, and the last die 940 may be released from the holding of the top bonding chuck 920. The thus-bonded first wafer 430 and die 940 have an optimal wafer / die shape.

[0060] In step S971, the unbonded portion of the first bonding film 651 that is not bonded to the second bonding film 952 may be etched and removed, and replaced with a dielectric layer 960 that separates and insulates the dies 940 from each other.

[0061] In step S972, the curvature / bending of each of another plurality of dies 930 to be bonded to die 940 is measured, a first bonding film 951 and a second bonding film 932 are respectively formed on the back surfaces of die 940 and another die 930, another die 930 is mounted on the top bonding head 921 of the top bonding device 920, and the top bonding device 920 and the bottom bonding device 410 are controlled to align and move towards each other so as to bond the first bonding film 951 and the second bonding film 932 to each other.

[0062] In step S973, die 940 and another die 930 are bonded to each other. For example, the controller 250 may control the bottom bonding chuck 410 and the top bonding chuck 920 to align and move towards each other until the first bonding film 951 contacts the second bonding film 932, and control the bottom bonding head 411 to apply a global pressure to die 940 and control the top bonding head 921 to apply a local pressure to another die 930 based on the bending measurement result of another die 930, so as to bond the second bonding film 932 to the first bonding film 951 and thus bond die 940 to another die 930.

[0063] In the foregoing description, specific details have been set forth, such as the specific geometry of the processing system and the description of various components and processes used therein. However, it should be understood that the techniques herein may be practiced in other embodiments without departing from these specific details, and such details are for purposes of explanation rather than limitation. The embodiments disclosed herein have been described with reference to the drawings. Similarly, for purposes of explanation, specific numbers, materials, and configurations have been set forth to provide a thorough understanding. However, the embodiments may be practiced without such specific details. Components having substantially the same functional construction are denoted by like reference characters, and thus any redundant description may be omitted.

[0064] Of course, for clarity, the order of discussion of the different steps as described herein has been presented. Generally, these steps may be performed in any suitable order. Additionally, although each of the different features, techniques, configurations, etc. herein may be discussed in different places in this disclosure, it is intended that each of the concepts may be performed independently of each other or in combination with each other. Accordingly, this disclosure may be implemented and viewed in many different ways.

[0065] Various techniques have been described as a number of discrete operations to assist in understanding the various embodiments. The order of description should not be construed to imply that these operations necessarily depend on order. In fact, these operations do not need to be performed in the order presented. The described operations may be performed in an order different from the order of the described embodiments. In additional embodiments, various additional operations may be performed and / or the described operations may be omitted.

[0066] As used herein, "substrate" or "target substrate" generally refers to an object to be processed in accordance with the present disclosure. A substrate can include any material part or structure of a device (particularly a semiconductor or other electronic device), and can be, for example, a base substrate structure (such as a semiconductor wafer, a mask), or a layer on or overlying a base substrate structure (such as a thin film). Thus, a substrate is not limited to any particular base structure, underlying layer, or overlying layer, whether patterned or unpatterned, but is envisioned to include any such layer or base structure, as well as any combination of layers and / or base structures. This description may refer to a particular type of substrate, but this is for illustrative purposes only.

[0067] Those skilled in the art will also understand that many changes can be made to the operation of the techniques explained above while still achieving the same purpose of the present disclosure. The scope of the present disclosure is intended to cover such variations. Thus, the foregoing description of embodiments of the present disclosure is not intended to be limiting. Rather, any limitations of embodiments of the present disclosure are provided in the appended claims.

Claims

1. A system for bonding two wafers, the system comprising: A bending measurement device configured to measure a first wafer and a second wafer to identify bending measurement results of the first wafer and the second wafer; A bonding device configured to bond the first wafer to the second wafer; And A controller coupled to the bending measurement device and the bonding device, the controller being configured to control the bonding device to apply pressure to the first wafer and the second wafer based on the bending measurement results to bond the first wafer to the second wafer.

2. The system according to claim 1, further comprising: A film forming device coupled to the controller, the film forming device being configured to form a bonding film on a first surface of the first wafer and the second wafer.

3. The system according to claim 2, further comprising: A heat generator coupled to the controller, the heat generator being configured to generate a heat pattern, Wherein the film forming device is further configured to form a first stress modifying film and a second stress modifying film on second surfaces of the first wafer and the second wafer respectively, the first stress modifying film and the second stress modifying film being responsive to heat such that the applied heat modifies internal stresses of the first stress modifying film and the second stress modifying film, The bending measurement device is further configured to measure the first wafer and the second wafer when the first stress modifying film and the second stress modifying film are respectively provided on the second surfaces of the first wafer and the second wafer and internal stresses of the first stress modifying film and the second stress modifying film have been modified to identify bending measurement results of the first wafer and the second wafer, The bending measurement device is further configured to measure the first wafer and the second wafer when no stress modifying film is formed on the second surfaces of the first wafer and the second wafer to identify another bending measurement result of the first wafer and the second wafer, and The controller is further configured to control the heat generator to generate the heat pattern and apply the heat pattern to the first stress modifying film and the second stress modifying film, the heat pattern corresponding to the another bending measurement result.

4. The system according to claim 2, further comprising: A light generator coupled to the controller, the light generator being configured to generate a pattern of light of a first wavelength and a second wavelength, Wherein the film forming device is further configured to form a first stress modifying film and a second stress modifying film on second surfaces of the first wafer and the second wafer respectively, the first stress modifying film and the second stress modifying film being responsive to the light of the first wavelength and the light of the second wavelength respectively such that exposure to the light of the first wavelength and the light of the second wavelength respectively modifies internal stresses of the first stress modifying film and the second stress modifying film, The bending measurement device is further configured to measure the first wafer and the second wafer when the first stress modification film and the second stress modification film are respectively formed on the second surfaces of the first wafer and the second wafer and the internal stresses of the first stress modification film and the second stress modification film have been modified, so as to identify the bending measurement results of the first wafer and the second wafer. The bending measurement device is further configured to measure the first wafer and the second wafer when no stress modification film is formed on the second surfaces of the first wafer and the second wafer, so as to identify another bending measurement result of the first wafer and the second wafer, and The controller is further configured to control the light generator to generate patterns of light with the first wavelength and the second wavelength and apply the patterns of light with the first wavelength and the second wavelength to the first stress modification film and the second stress modification film respectively, and the patterns of light with the first wavelength and the second wavelength correspond to the another bending measurement result.

5. The system according to claim 1, wherein, The second wafer is a die.

6. A method for bonding two wafers, the method comprising: Receiving a first wafer and a second wafer; Measuring the first wafer and the second wafer to identify the bending measurement results of the first wafer and the second wafer; And Applying pressure to the second surfaces of the first wafer and the second wafer based on the bending measurement results of the first wafer and the second wafer to bond the first wafer to the second wafer.

7. The method according to claim 6, further comprising: Forming a bonding film on the first surface of the first wafer.

8. The method according to claim 6, further comprising: Measuring the first wafer when no stress modification film is formed on the second surface of the first wafer to identify another bending measurement result of the first wafer; Forming a stress modification film on the second surface of the first wafer, the stress modification film being responsive to heat such that the applied heat modifies the internal stress of the stress modification film; And Applying a heat pattern to the stress modification film to modify the internal stress of the stress modification film, the heat pattern corresponding to the another bending measurement result, wherein measuring the first wafer and the second wafer to identify the bending measurement results of the first wafer and the second wafer includes measuring the first wafer and the second wafer when the stress modification film is formed on the second surface of the first wafer and the internal stress of the stress modification film has been modified, so as to identify the bending measurement results of the first wafer and the second wafer.

9. The method according to claim 6, further comprising: Measuring the first wafer when no stress modification film is formed on the second surface of the first wafer to identify another bending measurement result of the first wafer; Forming a stress modification film on the second surface of the first wafer, the stress modification film being responsive to light of a certain wavelength such that exposure to the light of the wavelength modifies the internal stress of the stress modification film; And Applying a pattern of light of a certain wavelength to the stress modification film to modify the internal stress of the stress modification film, the pattern of light of a certain wavelength corresponding to the another bending measurement result. Among them, measuring the first wafer and the second wafer to identify the bending measurement results of the first wafer and the second wafer includes measuring the first wafer and the second wafer when a stress modification film is formed on a second surface of the first wafer and the internal stress of the stress modification film has been modified, so as to identify the bending measurement results of the first wafer and the second wafer.

10. The method according to claim 6, wherein, The first wafer is a die.

11. The method according to claim 10, further comprising: measuring another die to identify another bending measurement result of the another die; and applying another pressure to a first surface of the another die based on the another bending measurement result to bond the another die to the die.

12. The method according to claim 10, further comprising: measuring another die to identify another bending measurement result of the another die; and applying another pressure to a first surface of the another die based on the another bending measurement result to bond the another die to the second wafer.

13. A bonding device for bonding two wafers, the bonding device comprising: a first bonding chuck having a first bonding head for mounting a first wafer thereon; and a second bonding chuck having a plurality of second bonding heads for mounting a second wafer thereon, the second bonding heads being configured to be individually controlled to apply local pressures to the second wafer to move the second wafer towards the first wafer so as to bond the second wafer to the first wafer, the local pressures corresponding to the bending measurement results of the first wafer and the second wafer.

14. The bonding device according to claim 13, wherein, The first bonding head applies a global pressure to the first wafer to move the first wafer towards the second wafer so as to bond the first wafer to the second wafer.

15. The bonding device according to claim 13, wherein, The first bonding chuck further includes one or more heating units provided in the first bonding head, the heating units being configured to provide heat to cure a bonding film for bonding the first wafer to the second wafer.

16. The bonding device according to claim 13, wherein, The second wafer is a die, and the second bonding heads are arranged in a manner matching the size of the die.

17. The bonding device according to claim 13, wherein, The first bonding head among the second bonding heads has a first shape, and the second bonding head among the second bonding heads has a second shape different from the first shape.

18. The bonding device according to claim 17, wherein, The first shape is circular.

19. The bonding device according to claim 17, wherein, The first shape is rectangular.

20. The bonding device according to claim 17, wherein, The first shape is crescent-shaped.

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