Temporary bonding structures, temporary substrates, and temporary bonding methods

Abstract

This disclosure relates to a temporary bonding structure, a temporary substrate, and a temporary bonding method. The temporary bonding structure includes: a temporary substrate, a device wafer, and bonding adhesive disposed between the temporary substrate and the device wafer; the device wafer has an edge trimming region on the side near the temporary substrate; the temporary substrate has a adhesive storage tank on the side near the device wafer; wherein the orthographic projection of the adhesive storage tank onto the device wafer is at least partially located within the edge trimming region, and the adhesive storage tank is used to store excess bonding adhesive during bonding of the device wafer and the temporary substrate. This disclosure can improve the quality of temporary bonding and ensure the reliability of wafer thinning processes and other back-side processes after temporary bonding.

Description

Technical Field

[0001] This disclosure relates to the field of semiconductor manufacturing technology, and in particular to a temporary bonding structure, a temporary wafer, and a temporary bonding method. Background Technology

[0002] With the development of very large-scale integrated circuits (VLSI) in semiconductors, existing technologies are approaching their physical limits. Driven by the goal of further miniaturizing and multifunctionalizing electronic products, 3D stacking technology is gradually being explored and applied. 3D stacking technology can stack multiple wafers using bonding techniques to achieve electrical interconnections at a three-dimensional level, reduce interconnection distances, improve transmission speed, reduce device size, and provide the possibility of heterogeneous structure integration.

[0003] Currently, wafer bonding technologies include permanent bonding and temporary bonding. Permanent bonding often has strict requirements on the wafer structure to be bonded and the post-bonding processes. Temporary bonding, on the other hand, offers greater flexibility because it allows for debonding processes. Among related technologies, the most common temporary bonding involves using bonding adhesive to bond the device wafer and the carrier wafer together, followed by thinning and a series of back-side processes, and then debonding using certain methods (including mechanical methods, chemical solvents, etc.).

[0004] However, during the aforementioned temporary bonding process, the bonding adhesive can easily coat the wafer edges, negatively impacting wafer thinning or other back-side processes. For example, it can clog grinding wheel teeth, causing wheel slippage and resulting in poor wafer surface roughness. Therefore, improving the quality of temporary bonding and ensuring the reliability of wafer thinning and other back-side processes after temporary bonding has become a pressing problem in the relevant technology. Summary of the Invention

[0005] Based on this, the present disclosure provides a temporary bonding structure, a temporary wafer carrier, and a temporary bonding method, which can improve the quality of temporary bonding and ensure the reliability of wafer thinning and other back-side processes after temporary bonding.

[0006] On one hand, some embodiments of this disclosure provide a temporary bonding structure, including: a temporary carrier, a device wafer, and bonding adhesive disposed between the temporary carrier and the device wafer; the device wafer has an edge trimming area on the side near the temporary carrier; the temporary carrier has a glue storage tank on the side near the device wafer; wherein the orthographic projection of the glue storage tank on the device wafer is at least partially located within the edge trimming area, and the glue storage tank is used to store the excess amount of bonding adhesive after the device wafer and the temporary carrier are bonded.

[0007] In some embodiments, the temporary carrier is provided with at least one overflow port on the side of the device wafer; the overflow port is located on the side of the adhesive storage tank away from the center region of the temporary carrier and connects the adhesive storage tank with the outer edge of the temporary carrier.

[0008] In some embodiments, the glue storage tank includes an annular groove; or, the glue storage tank includes a plurality of segmented arc-shaped grooves.

[0009] In some embodiments, the temporary carrier has a wafer bonding surface; the wall of the adhesive reservoir is connected to the wafer bonding surface, and there is an angle between the wall of the reservoir and the wafer bonding surface; wherein the value of the angle ranges from 90° to 150°.

[0010] In some embodiments, the included angle ranges from 90° to 120°.

[0011] In some embodiments, the longitudinal cross-sectional shape of the glue storage tank includes: T-shaped, inverted trapezoidal, semi-circular, or elliptical; the longitudinal cross-section is perpendicular to the extension direction of the glue storage tank.

[0012] In some embodiments, the volume of the glue storage tank satisfies the formula: V=H×W×L=KH t π(R 2 -r 2 ); where r = RR t Wherein, V is the volume of the glue storage tank, H is the depth of the glue storage tank, W is the equivalent width of the glue storage tank, L is the equivalent length of the glue storage tank, R is the radius of the device wafer, K is the adjustment coefficient, and H... t R is the height of the edge trimming area. t The width of the edge trimming area.

[0013] In some embodiments, the adjustment coefficient may range from 1.2 to 1.3.

[0014] In some embodiments, the width of the glue storage tank ranges from 0.25 mm to 1.05 mm; and / or the depth of the glue storage tank ranges from 130 μm to 200 μm.

[0015] In some embodiments, the width of the overflow port is 2 to 3 times the width of the glue storage tank.

[0016] In some embodiments, the bottom surface of the overflow port is on the same plane as the bottom surface of the glue storage tank; or, the bottom surface of the overflow port is an inclined surface, which is smoothly connected to the bottom surface of the glue storage tank, and the inclined surface is inclined in a direction away from the glue storage tank toward the side of the temporary carrier away from the device wafer.

[0017] In some embodiments, the temporary carrier is provided with a notch mark; there is a gap between the adhesive overflow port and the notch mark.

[0018] On the other hand, some embodiments of this disclosure provide a temporary substrate as described in any of the above embodiments.

[0019] In another aspect, some embodiments of this disclosure provide a temporary bonding method, including the following steps.

[0020] One edge of the device wafer is trimmed to form an edge trimming area.

[0021] A temporary carrier is provided, the temporary carrier having a wafer bonding surface and a glue reservoir located outside the wafer bonding surface.

[0022] Bonding adhesive is applied to one side surface of the device wafer where the edge trimming region is formed and / or to the wafer bonding surface.

[0023] The device wafer is pre-bonded to the temporary carrier using the bonding adhesive.

[0024] The device wafer and the temporary carrier are bonded together, and the excess amount of the bonding adhesive flows into the adhesive storage tank.

[0025] The bonding adhesive is cured to form a temporary bonding structure.

[0026] In some embodiments, the temporary bonding method further includes the following steps.

[0027] Debond the temporary bonding structure to separate the device wafer and the temporary carrier.

[0028] Clean and remove the bonding adhesive from the adhesive reservoir on the temporary carrier.

[0029] In this embodiment, by providing a glue storage tank on one side of the temporary carrier used for bonding the device wafer, the excess glue generated during bonding of the device wafer and the temporary carrier can be stored in the storage tank, thereby preventing the glue from wrapping around the edge of the device wafer. That is, in this embodiment, any glue overflow caused by pressure and / or temperature during the bonding process between the device wafer and the temporary carrier can be effectively stored in the storage tank, preventing the glue from overflowing and wrapping around the edge of the device wafer. This also avoids problems such as glue clogging the grinding wheel teeth or affecting other back-side processes of the device wafer. Therefore, the quality of temporary bonding can be effectively improved, ensuring the reliability of wafer thinning and other back-side processes after temporary bonding.

[0030] Furthermore, in some embodiments, the temporary carrier also has an overflow port connected to the adhesive storage tank. This allows the bonding adhesive stored in the storage tank to be easily and conveniently cleaned and removed through the overflow port after the bonding device wafer and temporary carrier are debonded, thus enabling the temporary carrier to be reused. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a bonding diagram of a temporary bonding structure provided in one embodiment;

[0033] Figure 2 This is a schematic diagram of another temporary bonding structure provided in one embodiment;

[0034] Figure 3 This is a schematic diagram of the structure of a temporary carrier provided in one embodiment;

[0035] Figure 4 for Figure 3 A schematic cross-sectional view of a temporary slide along the A-A' direction is shown.

[0036] Figure 5 This is a schematic diagram of another temporary carrier provided in one embodiment;

[0037] Figure 6 This is a schematic diagram of the structure of yet another temporary carrier provided in one embodiment;

[0038] Figure 7 for Figure 6 A schematic cross-sectional view of a temporary slide along the A-A' direction is shown.

[0039] Figure 8 for Figure 6 Another schematic cross-sectional view of a temporary slide along the A-A' direction is shown;

[0040] Figure 9 This is an enlarged view of the structure of a glue storage tank in a temporary substrate provided in one embodiment;

[0041] Figure 10 This is a flowchart illustrating a temporary bonding method provided in one embodiment;

[0042] Figure 11 This is a flowchart illustrating another temporary bonding method provided in one embodiment;

[0043] Figure 12 This is a schematic diagram of the structure of a device wafer after forming an edge trimming space, provided in one embodiment;

[0044] Figure 13 This is a schematic diagram of the structure of a temporary carrier provided in one embodiment;

[0045] Figure 14 This is a schematic diagram of the structure of a device wafer after coating with bonding adhesive, provided in one embodiment;

[0046] Figure 15 This is a schematic diagram of the structure obtained after pre-bonding a device wafer and a temporary carrier in one embodiment;

[0047] Figure 16 This is a schematic diagram of the structure obtained after curing the bonding adhesive in one embodiment;

[0048] Figure 17 This is a schematic diagram of the structure obtained after thinning the back side of a device wafer in one embodiment;

[0049] Figure 18 This is a schematic diagram of the structure obtained after etching the back side of a device wafer in one embodiment;

[0050] Figure 19 This is a schematic diagram of the structure obtained after forming a circuit layer on the back side of a device wafer, as provided in one embodiment.

[0051] Explanation of reference numerals in the attached figures:

[0052] 1-Temporary carrier, 11-Resin reservoir, 111-Arc-shaped groove, 12-Resin overflow port, 13-Notch marking; S-Wafer bonding surface;

[0053] 2-Device wafer, 21-Device layer, 22-Pad layer, 23-Through silicon via, 24-Backside circuit layer; B-Spacer;

[0054] ETA - Edge Trimming Area, H t - Height of the edge trimming area, R t - Width of the edge trimming area, H- Depth of the glue storage tank,

[0055] W - equivalent width of the glue storage tank, L - equivalent length of the glue storage tank 11, R - radius of the device wafer. Detailed Implementation

[0056] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.

[0057] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0058] It should be understood that when a component or layer is referred to as being "on," "adjacent to," "connected to," or "coupled to" other components or layers, it may be directly on, adjacent to, connected to, or coupled to other components or layers, or there may be intervening components or layers. Conversely, when a component is referred to as being "directly on," "directly adjacent to," "directly connected to," or "directly coupled to" other components or layers, there are no intervening components or layers.

[0059] It should be understood that although the terms first, second, etc., may be used to describe various elements, components, regions, layers, doping types, and / or portions, these elements, components, regions, layers, doping types, and / or portions should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, doping type, or portion from another element, component, region, layer, doping type, or portion. Therefore, without departing from the teachings of this invention, the first element, component, region, layer, doping type, or portion discussed below may be referred to as the second element, component, region, layer, or portion.

[0060] Spatial relation terms such as “below,” “under,” “below,” “under,” “above,” “above,” etc., are used herein to describe the relationship between one element or feature shown in the figure and other elements or features. It should be understood that, in addition to the orientation shown in the figure, spatial relation terms also include different orientations of the device in use and operation. For example, if the device in the figure is flipped, the element or feature described as “below,” “under,” or “below” will be oriented “above” the other element or feature. Therefore, the exemplary terms “below” and “under” can include both above and below orientations. Furthermore, the device may also include other orientations (e.g., rotated 90 degrees or other orientations), and the spatial descriptive terms used herein will be interpreted accordingly.

[0061] When used herein, the singular forms of “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising / including” or “having,” etc., specify the presence of the stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. Meanwhile, in this specification, the term “and / or” includes any and all combinations of the associated listed items.

[0062] Embodiments of the invention are described herein with reference to cross-sectional views that serve as schematic diagrams of ideal embodiments (and intermediate structures), thus allowing for the anticipation of variations in the illustrated shapes due to, for example, manufacturing techniques and / or tolerances. Therefore, embodiments of the invention should not be limited to the specific shapes of the regions shown herein, but rather include shape deviations due to, for example, manufacturing techniques. Consequently, the regions shown in the figures are substantially schematic, and their shapes do not represent the actual shapes of regions of the device, nor do they limit the scope of the invention.

[0063] Wafer bonding technology includes permanent bonding and temporary bonding. The most common temporary bonding involves using bonding adhesive to bond the device wafer and the carrier wafer together, and then, after thinning and a series of back-side processes, using certain methods (including mechanical methods, chemical solvents, etc.) to debond them.

[0064] In some embodiments, please refer to Figure 1 Figure (a) shows a temporary carrier 1 and a device wafer 2. After coating the front side of the device wafer 2 with bonding adhesive 3, the device wafer 2 and the temporary carrier 1 can be aligned and bonded. The temporary bonding structure after bonding the device wafer 2 and the temporary carrier 1 is shown in Figure (a). Figure 1 As shown in Figure (b), the bonding adhesive 3 is prone to encapsulating the edges of the device wafer 2 due to the influence of pressure and / or temperature. Please refer to [the relevant documentation / reference]. Figure 1 As shown in Figure (c), when performing thinning or other back-side processes on the back side of device wafer 2, the portion of the bonding adhesive 3 covering the edge of device wafer 2 is prone to clogging the grinding wheel teeth, causing the grinding wheel to slip and resulting in poor wafer surface roughness, thus adversely affecting the implementation of wafer thinning and other back-side processes.

[0065] Based on this, the present disclosure provides a temporary bonding structure, a temporary wafer carrier, and a temporary bonding method, which can improve the quality of temporary bonding and ensure the reliability of wafer thinning and other back-side processes after temporary bonding.

[0066] Please see Figure 2This disclosure provides a temporary bonding structure in some embodiments, including: a temporary carrier 1, a device wafer 2, and bonding adhesive 3 disposed between the temporary carrier 1 and the device wafer 2. The device wafer 2 has an edge trimming area (ETA) on the side near the temporary carrier 1. The temporary carrier 3 has a glue storage tank 11 on the side near the device wafer 2; wherein the orthographic projection of the glue storage tank 11 onto the device wafer 2 is at least partially located within the edge trimming area (ETA), and the glue storage tank 11 is used to store excess bonding adhesive 3 after the device wafer 2 and the temporary carrier 1 are bonded.

[0067] Optionally, the material of the device wafer 2 can be at least one of the following: silicon, silicon-on-insulator (SOI), silicon-on-insulator (SSOI), silicon-on-insulator (S-SiGeOI), and silicon-on-insulator (SiGeOI).

[0068] Optionally, the device wafer 2 includes a front side and a back side facing each other. The front side of the device wafer 2 may have a device layer 21 and a pad layer 22 formed thereon. The device layer 21 may contain structures constituting various device structures, such as a base region, an emitter region, a gate oxide layer, a gate, and an emitter. The device structure may be, for example, a MOSFET device, an IGBT device, etc. The pad layer 22 is used to realize the lead-out connections of the structures in the device layer 21 and may contain multiple pads or solder balls, etc.

[0069] Understandably, in a temporary bonding structure, the front side of device wafer 2 is typically bonded to temporary carrier 1 using bonding adhesive 3. Please refer to [further details]. Figure 2 An edge trimming area (ETA) is formed on the front side of device wafer 2. This trims the front edge of device wafer 2, removing the sharp edges of device wafer 2. This prevents the device wafer 2 from being damaged or causing other defects due to sharp edges in the temporary bonding process and other subsequent processes.

[0070] Optionally, the temporary carrier 1 can be made of silicon wafer, glass, or ceramic materials. The temporary carrier 1 supports the device wafer 2, facilitating thinning or other back-side processes on the back side of the device wafer 2 after temporary bonding. In some examples, the temporary carrier 1 uses a transparent material (e.g., glass), enabling double-sided alignment of the device wafer 2. Due to the lack of obstruction, the optical imaging quality is high, thus achieving high precision. In other examples, the temporary carrier 1 and the device wafer 2 use the same material, ensuring that the coefficient of thermal expansion of the temporary carrier 1 matches that of the device wafer 2, thereby eliminating side effects such as thermal stress and warpage caused by material differences in subsequent processes.

[0071] It should be added that the material of the temporary carrier 1 can be selected according to the process to be performed after the bonding wafer is formed, with silicon wafers, glass, or ceramic materials being the most common materials. In other embodiments, other materials that are compatible with semiconductor manufacturing processes, such as silicon compounds or germanium compounds, can also be used as the material of the temporary carrier 1.

[0072] Please combine Figure 2 , Figure 3 and Figure 4 It is understood that a glue storage tank 11 is provided on the side of the temporary carrier 3 near the device wafer 2. The shape, size and location of the glue storage tank 11 can be selected and set according to actual needs, with the limit that the orthogonal projection of the glue storage tank 11 on the device wafer 2 can be at least partially located within the edge trimming area (ETA).

[0073] Optionally, such as Figure 3 As shown, the glue storage tank 11 includes an annular groove.

[0074] Optionally, such as Figure 5 As shown, the glue storage tank 11 includes a plurality of segmented arc-shaped grooves 111. The plurality of arc-shaped grooves 111 are, for example, evenly distributed.

[0075] Here, after bonding the device wafer 2 to the temporary carrier 1, the orthographic projection of the adhesive reservoir 11 on the temporary carrier 1 onto the device wafer 2 is at least partially located in the edge trimming area (ETA). This can be manifested in the following specific implementations: the orthographic projection of the adhesive reservoir 11 on the temporary carrier 1 onto the device wafer 2 is located in the edge trimming area (ETA); or, the orthographic projection of the adhesive reservoir 11 on the temporary carrier 1 onto the device wafer 2 is located in the edge trimming area (ETA), and the boundary of the aforementioned orthographic projection near the center region of the device wafer 2 coincides with the boundary of the edge trimming area (ETA) near the center region of the device wafer 2; or, part of the orthographic projection of the adhesive reservoir 11 on the temporary carrier 1 onto the device wafer 2 is located in the edge trimming area (ETA), and the other part is located on the side of the edge trimming area (ETA) near the center region of the device wafer 2.

[0076] Optionally, the bonding adhesive 3 is used to temporarily bond the device wafer 2 and the temporary carrier 1. The material of the bonding adhesive 3 can be one of the following: heat-curing adhesive, ultraviolet light-curing adhesive, heat-decomposing adhesive, or laser-decomposing adhesive.

[0077] It should be added that the bonding adhesive 3 is used for temporary bonding, and its viscosity needs to be controlled during the bonding process. For example, after coating the bonding adhesive 3 on the front side of the device wafer 2, a pre-baking process can be used to ensure that the bonding adhesive 3 is in a solidified state and does not flow. Then, during the process of aligning and bonding the surface of the device wafer 2 coated with the bonding adhesive 3 to the temporary carrier 1, the bonding adhesive 3 is softened and flowed before solidifying through the combined action of pressure and temperature. Here, the pressure and temperature gradually increase and then decrease over time to match the viscosity control of the bonding adhesive 3.

[0078] In addition, the aforementioned adhesive storage tank 11 is used to store the excess amount of bonding adhesive 3 after the device wafer 2 is bonded to the temporary carrier 1. The excess amount of bonding adhesive 3 includes the amount of bonding adhesive 3 that overflows to the edge of the device wafer 2 due to pressure and / or temperature during the bonding process.

[0079] In this embodiment, by providing a glue storage tank 11 on one side of the temporary carrier 1 used for bonding the device wafer 2, the glue storage tank 11 can store excess glue 3 during the bonding of the device wafer 2 and the temporary carrier 1, thereby preventing the glue 3 from wrapping around the edge of the device wafer 2. That is, in this embodiment, any glue 3 overflowing due to pressure and / or temperature during the bonding process between the device wafer 2 and the temporary carrier 1 can be effectively stored in the glue storage tank 11, preventing the glue 3 from overflowing and wrapping around the edge of the device wafer 2. This also avoids the problem of the glue 3 clogging the grinding wheel teeth or affecting other back-side processes of the device wafer 2. Therefore, the quality of temporary bonding can be effectively improved, ensuring the reliability of the wafer thinning process and other back-side processes after temporary bonding.

[0080] In addition, the adhesive storage tank 11 provided on the temporary carrier 1 in this embodiment can also provide extra space for the high-temperature expansion and deformation of the bonding adhesive 3 in subsequent processes, so as to alleviate the defects caused to the device wafer 2 by the high-temperature deformation of the bonding adhesive 3 to a certain extent.

[0081] In some embodiments, please refer to Figure 6 and Figure 7 The temporary carrier 1 is also provided with at least one glue overflow port 12 on the side near the device wafer 2. The glue overflow port 12 is located on the side of the glue storage tank 11 away from the central area of ​​the temporary carrier 1, and connects the glue storage tank 11 with the outer edge of the temporary carrier 1.

[0082] Optionally, the temporary carrier 1 may have at least one glue overflow port 12 on any edge in different directions. For example, if the temporary carrier 1 is a circular piece, a glue overflow port 12 may be provided at the 3 o'clock, 6 o'clock, 9 o'clock and 12 o'clock directions of the temporary carrier 1 in a clockwise direction.

[0083] Optionally, such as Figure 6As shown, the temporary carrier 1 also has a notch mark 13, and there is a gap B between the glue overflow port 12 and the notch mark 13. For example, in a clockwise direction, the temporary carrier 1 has a notch mark 13 at the 6 o'clock position, and a glue overflow port 12 can be provided on the left and right sides of the notch mark 13. Furthermore, the gap B between the glue overflow port 12 and the notch mark 13 can be greater than 5mm, such as 6mm, 8mm, 10mm, or 15mm. Because the gap between the glue overflow port 12 and the notch mark 13 is relatively large, the glue overflow port 12 can be prevented from affecting the identification of the notch mark 13.

[0084] The aforementioned overflow port 12 connects the glue storage tank 11 to the outer edge of the temporary carrier 1. The depth of the overflow port 12 may be the same as or different from the depth of the glue storage tank 11. For some examples, please refer to... Figure 7 The bottom surface of the overflow outlet 12 and the bottom surface of the glue storage tank 11 are located on the same plane. For another example, please refer to... Figure 8 The bottom surface of the overflow port 12 is a slope, which is smoothly connected to the bottom surface of the glue storage tank 11, and the slope is inclined in a direction away from the glue storage tank 11 toward the side of the temporary carrier 1 away from the device wafer 2; for example, there is an included angle β between the slope and the extended plane of the bottom surface of the glue storage tank 11.

[0085] In this embodiment, the temporary carrier 1 is provided with an overflow port 12 that communicates with the adhesive storage tank 11. Thus, the bonding adhesive 3 stored in the adhesive storage tank 11 can be conveniently and easily cleaned and removed through the overflow port 12 after the device wafer 2 and the temporary carrier 1 are debonded, enabling the temporary carrier 1 to be reused. Furthermore, different cleaning agents can be selected for different bonding adhesives 3. For example, the bonding adhesive 3 can be cleaned and removed using the general-purpose cleaner isopropyl alcohol (IPA).

[0086] It is worth mentioning that, in some embodiments, the longitudinal cross-sectional shape of the glue storage tank 11 includes, but is not limited to, a T-shape, an inverted trapezoid, a semi-circle, or an ellipse. For example, the longitudinal cross-sectional shape of the glue storage tank 11 can also be a shape with sloping sides and an arc-shaped bottom. Here, the longitudinal cross-section of the glue storage tank 11 is perpendicular to the extending direction of the glue storage tank 11.

[0087] In some examples, such as Figure 9 As shown, the longitudinal section of the glue storage tank 11 is an inverted trapezoid to facilitate the storage of excess bonding glue 3.

[0088] In some examples, please refer to [link / reference]. Figure 9The temporary carrier 1 has a wafer bonding surface S. Here, the wafer bonding surface S refers to the core surface used to contact the bonding adhesive 3 to bond the device wafer 2. A glue reservoir 11 is formed on the outer side of the wafer bonding surface S. The wall of the glue reservoir 11 is connected to the wafer bonding surface S, and there is an angle α between the wall of the glue reservoir 11 and the wafer bonding surface S; wherein the value of the angle α ranges from 90° to 150°.

[0089] Optionally, the included angle α can range from 120° to 150°. For example, the included angle α can be 120°, 130°, 140°, or 150°.

[0090] Furthermore, it can be understood that the shape and size of the adhesive reservoir 11 can be designed according to the redundancy amount during the application of the bonding adhesive 3. The following provides an example of a possible implementation.

[0091] In some embodiments, please combine Figure 2 , Figure 6 and Figure 7 It is understood that the volume of the glue storage tank 11 satisfies the formula:

[0092] V = H × W × L = KH t π(R 2 -r 2 ); where r = RR t Where V is the volume of the glue storage tank 11, H is the depth of the glue storage tank 11, W is the equivalent width of the glue storage tank 11, L is the equivalent length of the glue storage tank 11, R is the radius of the device wafer 2, K is the adjustment coefficient, and H... t R is the height of the edge trimming region ETA. t The width of the edge trimming area ETA.

[0093] Here, the equivalent width W of the glue storage tank 11 can be defined as: the average width of the longitudinal section of the glue storage tank 11; or, for example, the equivalent width W of the glue storage tank 11 can be a minimum width or a maximum width defined according to requirements, etc. The equivalent length L of the glue storage tank 11 can be defined as: the total extension length of the glue storage tank 11. For example... Figure 6 As shown, the glue storage tank 11 is an annular tank, and the equivalent length of the glue storage tank 11 is the length L of the central annular line. For example... Figure 5 As shown, the glue storage tank 11 includes a plurality of arc-shaped grooves 111, and the equivalent length of the glue storage tank 11 is the sum of the extension lengths of each arc-shaped groove 111.

[0094] In this embodiment, the volume of the adhesive storage tank 11 can be matched with the volume of the edge trimming area ETA, thereby ensuring that the adhesive storage tank 11 can fully store the redundant amount of bonding adhesive 3, and that the bonding adhesive 3 will not wrap around the edge of the device wafer 2.

[0095] Optionally, the adjustment coefficient (K) in the above formula is an amplification coefficient, and the value range of the adjustment coefficient (K) includes: 1.2 to 1.3; for example, it can be: 1.2, 1.25 or 1.3.

[0096] Optionally, the radius R of device wafer 2 is 150 mm.

[0097] In some embodiments, the width of the glue storage tank 11 ranges from 0.25 mm to 1.05 mm; and / or the depth of the glue storage tank 11 ranges from 130 μm to 200 μm.

[0098] Furthermore, in some embodiments, the temporary substrate 1 is provided with an overflow port 12, the width of which is 2 to 3 times the width of the adhesive reservoir 11, for example, 2, 2.5, or 3 times. The wider overflow port 12 facilitates cleaning of the temporary substrate 1.

[0099] On the other hand, some embodiments of this disclosure provide a temporary carrier 1 as described in any of the foregoing embodiments for bonding device wafers 2 and forming the temporary bonding structure described in the foregoing embodiments. The structure of the temporary carrier 1 can be found in the relevant descriptions in the foregoing embodiments, and will not be detailed here.

[0100] On the other hand, please refer to Figure 10 and Figure 11 This disclosure provides a temporary bonding method for preparing the temporary bonded structures described in the foregoing embodiments. The temporary bonding method includes the following steps.

[0101] S100 trims one edge of the device wafer to form an edge trimming area.

[0102] S200 provides a temporary carrier having a wafer bonding surface and a glue reservoir located outside the wafer bonding surface.

[0103] S300, bonding adhesive is applied to one side surface of the edge trimming area of ​​the device wafer and / or the wafer bonding surface of the temporary carrier.

[0104] S400 uses bonding adhesive to pre-bond device wafers onto temporary carriers.

[0105] S500, bonding device wafers and temporary carriers, with excess bonding adhesive flowing into the adhesive reservoir.

[0106] S600 is a curing bonding adhesive that forms a temporary bonding structure.

[0107] It is understood that, in the embodiments of this disclosure, unless otherwise expressly stated herein, the execution order of the steps in the method is not strictly limited. These steps may not necessarily be executed in the described sequence number, and may have other execution methods. Moreover, at least a portion of any step may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily completed at the same time, but may be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but may be executed alternately or in turn with other steps or at least a portion of the sub-steps or stages of other steps.

[0108] The bonding adhesive described above is used to bond device wafers and temporary carriers. In step S300, the bonding adhesive can be applied to one side of the edge trimming area of ​​the device wafer, or to the wafer bonding surface of the temporary carrier, or to both the device wafer and the temporary carrier. This disclosure does not limit the specific application of the adhesive.

[0109] Furthermore, in step S400, the pre-bonding of the device wafer to the temporary carrier based on the bonding adhesive can be specifically manifested as follows: after applying the bonding adhesive, the bonding adhesive is first baked and solidified to a non-flowing state, and then the device wafer and the temporary carrier are aligned and bonded using the bonding adhesive. In steps S500 and S600, the bonding of the device wafer and the temporary carrier, as well as the curing of the bonding adhesive, can be specifically manifested as follows: by controlling the changes in pressure and temperature, the bonding adhesive is first softened and flowed before curing and bonding, thereby obtaining a temporary bonding structure. Here, the pressure and temperature can be increased and then decreased over time; and, in the softened and flowable state, the excess amount of bonding adhesive flows into the adhesive storage tank.

[0110] In this embodiment, during the bonding process between the device wafer and the temporary carrier, any excess bonding adhesive (redundancy) caused by pressure and / or temperature can be effectively stored in the adhesive reservoir, preventing the adhesive from overflowing and covering the edges of the device wafer. This avoids the problem of bonding adhesive clogging the grinding wheel teeth or affecting other back-side processes of the device wafer. Therefore, the quality of temporary bonding can be effectively improved, ensuring the reliability of wafer thinning and other back-side processes after temporary bonding.

[0111] It should be noted that after the bonding adhesive is cured to form a temporary bonding structure in step S600, the back side of the device wafer can be thinned or other back side processes can be performed according to actual needs. For example, the back side thinning of the device wafer can be performed by methods such as mechanical grinding, chemical mechanical polishing (CMP), chemical etching, or plasma etching.

[0112] Based on this, in some embodiments, please refer to Figure 11 The temporary bonding method further includes the following steps.

[0113] S700 debonds temporary bonding structures to separate the device wafer from the temporary carrier.

[0114] S800 cleans and removes bonding adhesive from the adhesive reservoir on the temporary substrate.

[0115] In step S700, the debonding of the temporary bonding structure can be selected based on the material of the bonding adhesive. For example, the temporary bonding structure can be treated by light, heat and chemical reactions, and then the device wafer and temporary carrier can be mechanically separated.

[0116] In step S800, after debonding the temporary bonding structure, the bonding adhesive in the adhesive reservoir on the temporary carrier can be cleaned and removed to enable the temporary carrier to be recycled.

[0117] In addition, in actual production, after debonding the temporary bonding structure, the device wafer can be further processed, such as cleaning or dicing.

[0118] To more clearly illustrate the temporary bonding method in the embodiments of this disclosure, the following is combined with... Figures 12-19 Taking the application of bonding adhesive to the surface of a device wafer as an example, a temporary bonding method in the embodiments of this disclosure is illustrated by way of example.

[0119] In step S100, please refer to Figure 12 One edge of device wafer 2 is trimmed to form the edge trimming area (ETA).

[0120] Optionally, the device wafer 2 includes a front side and a back side facing each other. The front side of the device wafer 2 may have a through-silicon via (STV) 23, a device layer 21, and a pad layer 22 formed therein. The STV 23 may be buried within the device wafer 2. The device layer 21 may contain structures constituting various device structures, such as a base region, an emitter region, a gate oxide layer, a gate, and an emitter. These device structures may be, for example, MOSFET devices, IGBT devices, etc. The device layer 21 may be formed on the surface of the device wafer 2. The pad layer 22 is used to implement the lead-out connections of the structures in the device layer 21 and may contain multiple pads or solder balls. The pad layer 22 may be formed on the side of the device layer 21 opposite to the STV 23.

[0121] Optionally, edge trimming of device wafer 2 can be performed after the aforementioned through-silicon via 23, device layer 21, and pad layer 22 are formed on the front side of device wafer 2. The edge trimming area (ETA) is formed at the front edge of device wafer 2, and the height and width of the edge trimming area (ETA) can be selected and set according to requirements.

[0122] For example, the height H of the edge trimming area ETA tThe width R of the edge trimming area ETA can be determined based on the thinning thickness on the back side of the subsequent device wafer 2. t The height of the edge-trimmed region ETA can be determined based on the edge roundness of the device wafer 2. Optionally, the height range of the edge-trimmed region ETA includes 130μm to 200μm; for example, it can be 130μm, 150μm, 180μm, or 200μm. Optionally, the width range of the edge-trimmed region ETA includes 0.3mm to 1mm; for example, it can be 0.3mm, 0.5mm, 0.8mm, or 1mm.

[0123] Alternatively, after forming the edge trimming area (ETA) at the edge of the device wafer 2, the device wafer 2 can be cleaned with deionized water to remove residue generated from the edge of the device wafer 2.

[0124] In step S200, please refer to Figure 13 A temporary carrier 1 is provided, which has a wafer bonding surface S and a glue storage tank 11 located outside the wafer bonding surface S.

[0125] The structure of the temporary carrier 1 can be found in the relevant descriptions in some of the foregoing embodiments, and will not be repeated here.

[0126] Optionally, the temporary carrier 1 is also provided with an overflow port 12 that connects the glue storage tank 11 with the outer edge of the temporary carrier 1.

[0127] In step S300, please refer to Figure 14 Bonding adhesive 3 is applied to one side of the edge trimming region ETA formed on the device wafer 2.

[0128] Here, the coating thickness of the bonding adhesive 3 depends on the height of the protrusions on the surface of the device wafer 2. For example, the coating thickness of the bonding adhesive 3 is greater than the sum of the thicknesses of the device layer 21 and the pad layer 22 to ensure good sealing of the front side of the device wafer 2. Furthermore, the difference between the coating thickness of the bonding adhesive 3 and the sum of the thicknesses of the device layer 21 and the pad layer 22 can be determined based on the bonding area of ​​the device wafer 2 to ensure a target margin. Optionally, the coating thickness of the bonding adhesive 3 can range from 30 μm to 60 μm; for example, it can be 30 μm, 40 μm, 50 μm, or 60 μm.

[0129] In addition, after coating the bonding adhesive 3 on one side of the edge trimming region ETA formed on the device wafer 2, the bonding adhesive 3 can be solidified to a non-flowing state by baking the device wafer 2.

[0130] In step S400, please refer to Figure 15 The device wafer 2 is pre-bonded to the temporary carrier 1 based on the bonding adhesive 3.

[0131] Here, pre-bonding can specifically mean aligning and bonding the device wafer 2 and the temporary carrier 1 using bonding adhesive 3.

[0132] In step S500, please refer to Figure 16 The redundant amount of bonding adhesive 3 flows into the adhesive storage tank 11, which is used to bond the device wafer 2 and the temporary carrier 1.

[0133] In step S600, please refer to... Figure 16 , cure the bonding adhesive 3, and form a temporary bonding structure.

[0134] Please combine Figure 15 and Figure 16 It is understood that by controlling the changes in pressure and temperature, the bonding adhesive 3 can be softened and flowed before solidifying and bonding, thereby obtaining a temporary bonded structure. Furthermore, the pressure and temperature can be increased and then decreased over time. In this way, when the bonding adhesive 3 is in a softened and flowable state, the overflow (i.e., redundancy) caused by pressure and / or temperature can flow into the adhesive storage tank 11.

[0135] In step S500, optionally, the bonding temperature of the temporary bonding structure can be 250℃~300℃. Optionally, the bonding pressure of the temporary bonding structure can be 0.6 MPa. Optionally, the bonding time of the temporary bonding structure can be 8 min~14 min.

[0136] In step S600, optionally, the curing temperature of the bonding adhesive 3 can be 200℃~275℃. Optionally, the curing time of the bonding adhesive 3 can be 1 hour.

[0137] It should be noted that after the bonding adhesive is cured in step S600 to form a temporary bonding structure, the back side of the device wafer can be thinned or other back side processes can be performed according to actual needs.

[0138] Please see Figure 17 The thickness of device wafer 2 is reduced from the back side to the target thickness, for example, the thickness of device wafer 2 can be reduced to 75 μm.

[0139] Furthermore, after thinning the device wafer 2, chemical mechanical polishing can be used on the thinned surface of the device wafer 2 to improve surface quality. Optionally, the thickness of the device wafer 2 can be reduced to 65 μm by chemical mechanical polishing.

[0140] Please see Figure 18 The polished surface of the device wafer 2 is etched to expose the through-silicon via 23.

[0141] Please see Figure 19 Based on through-silicon vias, a back circuit layer 24 is formed on the device wafer 2.

[0142] Here, the structure of the through-silicon via 23 and the back circuit layer 24 can be selected and configured according to requirements, and this embodiment does not limit it.

[0143] After performing the above-described process on the back side of device wafer 2, the temporary bonding structure can be debonded to separate device wafer 2 and temporary carrier 1. Then, by cleaning to remove the bonding adhesive 3 from the adhesive reservoir 11 on temporary carrier 1, temporary carrier 1 can be recycled.

[0144] In the description of this specification, references to terms such as "some embodiments," "other embodiments," and "ideal embodiments" indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative descriptions of the above terms do not necessarily refer to the same embodiments or examples.

[0145] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features of the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0146] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A temporary bonding structure, characterized in that, include: The device includes a temporary carrier, a device wafer, and bonding adhesive disposed between the temporary carrier and the device wafer; the device wafer has an edge trimming area on the side near the temporary carrier; the temporary carrier has a bonding adhesive reservoir on the side near the device wafer; wherein, The orthogonal projection of the adhesive reservoir onto the device wafer is at least partially located within the edge trimming area, and the adhesive reservoir is used to store excess amount of bonding adhesive after the device wafer is bonded to the temporary carrier.

2. The temporary bonding structure according to claim 1, characterized in that, The temporary carrier is provided with at least one overflow port on the side of the device wafer; the overflow port is located on the side of the adhesive storage tank away from the center area of ​​the temporary carrier and connects the adhesive storage tank with the outer edge of the temporary carrier.

3. The temporary bonding structure according to claim 1 or 2, characterized in that, The glue storage tank includes an annular groove; Alternatively, the glue storage tank may include multiple arc-shaped grooves arranged in segments.

4. The temporary bonding structure according to claim 1 or 2, characterized in that, The temporary carrier has a wafer bonding surface; the wall of the adhesive storage tank is connected to the wafer bonding surface, and there is an angle between the tank wall and the wafer bonding surface; The included angle ranges from 90° to 150°.

5. The temporary bonding structure according to claim 4, characterized in that, The included angle ranges from 90° to 120°.

6. The temporary bonding structure according to claim 1 or 2, characterized in that, The longitudinal cross-sectional shape of the glue storage tank includes: T-shaped, inverted trapezoidal, semi-circular or elliptical; the longitudinal cross-section is perpendicular to the extension direction of the glue storage tank.

7. The temporary bonding structure according to claim 6, characterized in that, The volume of the glue storage tank satisfies the formula: V = H × W × L = KH t π(R 2 -r 2 ); where r = RR t ; Where V is the volume of the glue storage tank, H is the depth of the glue storage tank, W is the equivalent width of the glue storage tank, L is the equivalent length of the glue storage tank, R is the radius of the device wafer, K is the adjustment coefficient, and H t R is the height of the edge trimming area. t The width of the edge trimming area.

8. The temporary bonding structure according to claim 7, characterized in that, The adjustment coefficient ranges from 1.2 to 1.

3.

9. The temporary bonding structure according to claim 1 or 2, characterized in that, The width of the glue storage tank ranges from 0.25mm to 1.05mm. And / or, the depth of the glue storage tank ranges from 130μm to 200μm.

10. The temporary bonding structure according to claim 2, characterized in that, The width of the overflow port is 2 to 3 times the width of the glue storage tank.

11. The temporary bonding structure according to claim 2, characterized in that, The bottom surface of the overflow port and the bottom surface of the glue storage tank are located on the same plane; or, The bottom surface of the overflow port is a slope, which is smoothly connected to the bottom surface of the glue storage tank, and the slope is inclined in a direction away from the glue storage tank toward the side of the temporary carrier away from the device wafer.

12. The temporary bonding structure according to claim 2, characterized in that, The temporary carrier is marked with a notch; there is a gap between the overflow port and the notch mark.

13. A temporary slide as claimed in any one of claims 1 to 12.

14. A temporary bonding method, characterized in that, include: One edge of the device wafer is trimmed to form an edge trimming area; A temporary carrier is provided, the temporary carrier having a wafer bonding surface and a glue reservoir located outside the wafer bonding surface; A bonding adhesive is applied to one surface of the device wafer on which the edge trimming region is formed and / or on the wafer bonding surface; The device wafer is pre-bonded to the temporary carrier based on the bonding adhesive; The device wafer and the temporary carrier are bonded together, and the excess amount of the bonding adhesive flows into the adhesive storage tank. The bonding adhesive is cured to form a temporary bonding structure.

15. The temporary bonding method according to claim 14, characterized in that, The temporary bonding method further includes: Debond the temporary bonding structure to separate the device wafer and the temporary carrier. Clean and remove the bonding adhesive from the adhesive reservoir on the temporary carrier.

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