Donor substrate processing method and composite substrate
By employing a double chamfering process and a cover plate for protection, the problem of edge cracking of the donor substrate was solved, the bonding surface quality and uniformity were improved, production costs were reduced, and efficient recycling of the donor substrate was achieved.
Patent Information
- Application Number
- CN202410927677.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-11
- Publication Date
- 2026-01-16
AI Technical Summary
The poor flatness of the edge region of the donor substrate makes it prone to failure during bonding, resulting in edge cracking. Although the existing technology has improved this by performing a chamfering process, there are still problems with unbonded areas and edge cracking, which are particularly significant during multiple recycling.
The process involves two chamfering steps: the first step forms a first L-shaped chamfer, and the second step forms a second L-shaped chamfer. Before the second chamfer, a cover plate is used to protect the bonding surface. Combined with chemical mechanical polishing and ion implantation, this ensures neat edges and high-quality bonding surfaces.
It improves the neatness of the donor substrate edge, avoids damage to the bonding surface caused by particle contamination, improves the bonding surface quality, reduces production costs, and increases production efficiency.
Smart Images
Figure CN121358262A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of semiconductor processing, and in particular to a donor substrate processing method and a composite substrate. BACKGROUND
[0002] The third generation semiconductor material has a wide range of application scenarios, but the production capacity is generally low and the price is high. One way to reduce costs is to use a composite substrate process, transfer the donor substrate to the acceptor substrate by bonding, and then peel off the donor substrate by a splitting process to form a bonded substrate. The peeled donor substrate continues to be used for wafer bonding, so that one piece of donor substrate can be used to form multiple bonded substrates, thereby reducing costs.
[0003] However, the edge region of the donor substrate has poor flatness, which is prone to failure and edge cracking during bonding. In the prior art, a chamfering process is performed on the edge of the donor substrate before bonding to make the edge of the donor substrate a right angle, thereby improving the flatness of the edge. The surface of the chamfered donor substrate is then polished and bonded to the acceptor substrate to form the final bonded substrate. Although the above scheme can effectively improve the bonding quality of the edge of the bonded substrate, the edge of the bonded substrate is still not perfect and there will still be a small amount of un-bonded area, especially as the number of recycling of the donor substrate increases, the edge cracking problem becomes more and more prominent.
[0004] Therefore, there is an urgent need for a donor substrate processing method and a composite substrate to solve the above problems. SUMMARY
[0005] Based on the above, the purpose of the present application is to provide a donor substrate processing method and a composite substrate, which realizes the edge alignment of the donor substrate and the overall quality of the bonding surface of the donor substrate, and avoids the damage of the particles introduced by the second chamfering to the bonding surface.
[0006] To achieve the above purpose, the present application adopts the following technical scheme:
[0007] On the one hand, a donor substrate processing method comprises the following steps:
[0008] S1, performing first chamfering on the edge of the donor substrate and forming a first L-shaped chamfer;
[0009] S2, polishing the bonding surface of the donor substrate;
[0010] S3, connecting a cover plate to the bonding surface, the size of the cover plate being reduced by a preset distance based on the size of the bonding surface, so that the part of the bonding surface not covered by the cover plate forms a to-be-chamfered area, and the to-be-chamfered area is arranged around the bonding surface;
[0011] S4, secondly chamfering the edge of the donor substrate to remove the to-be-chamfered area and form a second L-shaped chamfer, the second L-shaped chamfer corresponding to forming a bonding layer;
[0012] S5, separating the cover plate and the donor substrate to obtain the donor substrate with the bonding layer.
[0013] As a preferred technical scheme of the donor substrate processing method, before the S1 step, the donor substrate is bonded on a support substrate.
[0014] As a preferred technical scheme of the donor substrate processing method, the donor substrate and the support substrate are made of the same material.
[0015] As a preferred technical scheme of the donor substrate processing method, in the S1 step, the depth of the first chamfer is greater than the thickness of the donor substrate.
[0016] As a preferred technical scheme of the donor substrate processing method, in the S3 step, the cover plate is bonded to the bonding surface by using glue.
[0017] As a preferred technical scheme of the donor substrate processing method, the glue completely fills the bonding surface.
[0018] As a preferred technical scheme of the donor substrate processing method, in the S4 step, the depth of the second chamfer is 0.8 μm-1.2 μm.
[0019] As a preferred technical scheme of the donor substrate processing method, the donor substrate processing method further comprises:
[0020] S6, peeling off part of the bonding layer from the donor substrate;
[0021] S7, removing the remaining bonding layer on the donor substrate;
[0022] S8, removing the donor substrate with the bonding layer to enter the S3 step and recycle.
[0023] As a preferred technical scheme of the donor substrate processing method, after the S2 step and before the S3 step, further comprising forming an ion implantation layer on the side of the donor substrate close to the bonding surface;
[0024] The ion implantation layer is located in the bonding layer.
[0025] On the other hand, a composite substrate is provided, which is formed by cracking the bonding layer of the above-mentioned donor substrate and the acceptor substrate after bonding.
[0026] The present application has the following advantages:
[0027] The application provides a donor substrate processing method and a composite substrate, which improves the problem of edge collapse of the donor substrate after polishing the bonding surface of the donor substrate, restores the second L-shaped straight angle of the edge of the donor substrate, ensures the edge of the donor substrate and the overall quality of the bonding surface of the donor substrate, and is crucial for preventing edge damage or fragments in subsequent process steps.
[0028] Furthermore, the application connects a cover plate to the bonding surface before the second chamfering, protects the bonding surface through the cover plate, and avoids damage of the bonding surface caused by particles introduced by the second chamfering. BRIEF DESCRIPTION OF DRAWINGS
[0029] In order to more clearly illustrate the technical solutions in the embodiments of the application, the drawings needed in the description of the embodiments of the application will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative effort on the basis of the contents of the embodiments of the application and the drawings.
[0030] Figure 1 is a flowchart of the donor substrate processing method provided by the specific embodiment of the application;
[0031] Figure 2 is a process flow diagram of the donor substrate processing method provided by the specific embodiment of the application;
[0032] Figure 3 is a structure diagram of the donor substrate in the S4 step of the donor substrate processing method provided by the specific embodiment of the application.
[0033] The drawings are marked as follows:
[0034] 1, donor substrate; 2, cover plate; 3, glue; 4, support substrate; 5, first L-shaped chamfer; 6, second L-shaped chamfer. DETAILED DESCRIPTION
[0035] The application will be further described in detail below in combination with the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the application, but not to limit the application. In addition, it should be noted that, for the convenience of description, only the parts related to the application are shown in the drawings, but not all the structures.
[0036] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.
[0037] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.
[0038] In the description of this embodiment, the terms "upper," "lower," "left," and "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first" and "second" are used only for distinction in description and have no special meaning.
[0039] like Figure 1 and Figure 2 As shown, this embodiment provides a donor substrate processing method, which includes the following steps:
[0040] S1. Perform a first chamfer on the edge of the donor substrate 1 to form a first L-shaped chamfer 5, so that the edge of the donor substrate 1 is neat and free of tearing. The first L-shaped chamfer 5 is a right angle and should not have sharp angles, as sharp angles are prone to breakage and chipping.
[0041] S2, polishing the bonding surface of the donor substrate 1, wherein the polishing is chemical mechanical polishing (CMP), and a suitable polishing pad and polishing liquid are selected in advance, and the polishing parameters such as pressure, rotation speed and time are adjusted. The donor substrate 1 is placed in a polishing device for polishing, and the whole surface contact mode helps to remove the surface damage layer and defects. The edge region of the donor substrate 1 is chamfered to be a right angle, and in the process of chemical mechanical polishing, the first L-shaped chamfer 5 directly contacts the polishing pad, causing the right angle to become a round angle (collapse) abnormality. After the chemical mechanical polishing is completed, the surface polishing liquid residue is cleaned and dried.
[0042] It should be noted that CMP is a technology combining mechanical grinding and chemical corrosion, which can form a smooth and flat surface on the surface of the grinding medium. In the CMP process, the bonding surface of the donor substrate 1 is gradually flattened due to the action of mechanical grinding and chemical corrosion. However, if the chamfer of the edge part is a right angle, the right angle area may directly contact the polishing pad during the CMP process, causing the right angle part to be excessively ground, thereby forming a round angle or collapse. This collapse phenomenon will affect the processing quality of the surface of the donor substrate 1, especially it may cause damage or chipping of the edge part in the subsequent process steps.
[0043] S3, the cover plate 2 is connected to the bonding surface, the size of the cover plate 2 is based on the size of the bonding surface and is reduced by a predetermined distance, so that the part of the bonding surface not covered by the cover plate 2 forms a to-be-chamfered area, and the to-be-chamfered area is annularly arranged on the bonding surface; before the second chamfering, the cover plate 2 is connected to the bonding surface, and the bonding surface is protected by the cover plate 2, avoiding damage to the bonding surface caused by particles introduced by the second chamfering.
[0044] S4, the edge of the donor substrate 1 is chamfered for the second time to remove the to-be-chamfered area and form a second L-shaped chamfer 6, and the second L-shaped chamfer 6 corresponds to the formation of the bonding layer; in order to improve the problem of collapse abnormality of the edge of the donor substrate 1 after polishing the bonding surface of the donor substrate 1, the second chamfering of the donor substrate 1 restores the right angle of the second L-shaped chamfer 6 of the edge of the donor substrate 1, ensures the neatness of the edge of the donor substrate 1 and the overall quality of the bonding surface of the donor substrate 1, and is crucial for preventing damage or chipping of the edge part in the subsequent process steps.
[0045] S5, the cover plate 2 and the donor substrate 1 are separated, and the donor substrate 1 with the bonding layer is obtained.
[0046] S6, part of the bonding layer is peeled off from the donor substrate 1; wherein the donor substrate 1 with the bonding layer is applied to bond with a receiver substrate and is peeled off, and the peeled donor substrate 1 is processed for the next time to realize recycling and reduce production cost.
[0047] S7, removing the remaining bonding layer on the donor substrate; wherein the second L-shaped chamfer 6 corresponds to the bonding layer, the second L-shaped chamfer 6 and the layer where the second L-shaped chamfer 6 is located are polished to remove the remaining bonding layer, so that the diameter of the bonding surface of the donor substrate 1 is the same in each recycling process, meeting the production requirements.
[0048] S8, the donor substrate 1 with the removed bonding layer enters the S3 step and is recycled.
[0049] Preferably, before the S1 step, the donor substrate 1 is bonded to the support substrate 4. The donor substrate 1 is made of a high-quality material sheet source. After the donor substrate 1 is bonded to the support substrate 4, the strength of the donor substrate 1 is increased, and the recycling times are improved. Further preferably, the donor substrate 1 and the support substrate 4 are made of the same material and are bonded with the same material, so that the thermal expansion coefficients are the same and deformation after high temperature is prevented.
[0050] As shown in FIG. 1, in the S1 step, the first chamfering is performed on the donor substrate 1 to remove the circular edge of the donor substrate 1. Figures 1-3 As shown in FIG. 1, in the S1 step, the first chamfering is performed on the donor substrate 1 to remove the circular edge of the donor substrate 1. In this embodiment, the width A of the first chamfering (the removal distance along the radial direction of the donor substrate 1 during chamfering) is 1 mm, and the circular edge of the donor substrate 1 itself is removed. The depth of the first chamfering (the removal distance along the thickness direction of the donor substrate 1 during chamfering) is the thickness of the donor substrate 1 plus 1 μm-10 μm.
[0051] It should be particularly noted that if the first chamfering is not performed to remove the circular edge of the donor substrate 1, and the second chamfering is directly performed to form the bonding layer, the amount of material to be removed each time is large, and the machining stress is large. After the bonding layer is lower than the center line of the donor substrate 1 (the center line is located in the middle of the donor substrate 1 along the thickness direction), the remaining donor substrate 1 is thin, and the edge support of the donor substrate 1 is weak. When chamfering is performed again, edge collapse occurs, resulting in that part of the donor substrate 1 cannot be used. To solve the above problems, in this embodiment, the first chamfering completely removes the circular edge of the donor substrate 1, and the second chamfering forms the bonding layer by chamfering a certain depth each time. The two chamferings reduce the amount of material to be removed each time for the second chamfering, reduce the machining stress, and further reduce the risk of edge collapse of the donor substrate 1.
[0052] It should be noted that after the S2 step and before the S3 step, the donor substrate processing method further includes forming an ion implantation layer on one side of the donor substrate 1 close to the bonding surface; the ion implantation layer is located in the bonding layer. After the bonding layer of the donor substrate 1 is bonded to the acceptor substrate, a composite substrate and a remaining donor substrate 1 are formed after peeling, the remaining bonding layer of the remaining donor substrate 1 is removed, the second chamfering is performed again, and the recycling is performed.
[0053] Preferably, in the S3 step, the cover plate 2 is bonded to the bonding surface by the adhesive 3, facilitating the subsequent separation of the cover plate 2 from the bonding surface. In the embodiment, the adhesive 3 is a foaming adhesive. Further, the size of the cover plate 2 is reduced by a preset distance of 1 mm based on the size of the bonding surface, and the preset distance is the same as the width A of the second chamfering, and the cover plate 2 can effectively prevent the foaming adhesive from directly contacting the grinding wheel during the second chamfering, thereby preventing pollution of the machine and the grinding wheel.
[0054] Further preferably, when the adhesive 3 is applied, the adhesive 3 needs to completely fill the bonding surface to ensure that the outer edge of the donor substrate 1 is not contaminated during the second chamfering. When the amount of the adhesive 3 is too much, the adhesive 3 will overflow the edge of the connection between the cover plate 2 and the bonding surface, and the overflowed adhesive 3 will also be removed during the second chamfering, without affecting the quality of the donor substrate 1.
[0055] Further, in the S4 step, the to-be-chamfered area is chamfered for the second time, and the depth of the second chamfering is 0.8 um-1.2 um, which can be adaptively selected according to the ion implantation layer depth of the donor substrate 1, and the width B of the second chamfering is 1 mm. The second chamfering can effectively remove the edge collapse abnormality caused by CMP, restore the right angle of the chamfered area of the edge of the donor substrate 1, and ensure the edge of the donor substrate 1 to be neat and the overall quality of the bonding surface.
[0056] Further, in the S2 step, the cover plate 2 and the donor substrate 1 are placed in an environment of 100℃-200℃ for 5 min-20 min, and the high temperature promotes the foaming agent inside the foaming adhesive to form bubbles, so that the cover plate 2 and the donor substrate 1 are separated, and the cover plate 2 after separation is used for processing of the next donor substrate 1. Preferably, the roughness of the side of the cover plate 2 close to the bonding surface is greater than the roughness of the bonding surface. In the embodiment, the surface roughness of the polished bonding surface is 0.05 nm-1 nm, and the roughness of the side of the cover plate 2 close to the bonding surface is greater than 5 nm. The high temperature promotes the foaming agent inside the foaming adhesive to form bubbles, and after the cover plate 2 and the donor substrate 1 are separated, the foaming adhesive will be attached to the side with larger roughness, i.e., attached to the cover plate 2; the cover plate 2 with the attached foaming adhesive is cleaned to remove the residual foaming adhesive, and is used for processing of the next donor substrate 1, so that the cover plate 2 is repeatedly used, thereby reducing the production cost.
[0057] The embodiment precisely controls the depth and width of the first chamfering and the second chamfering, combines the CMP processing and the cover plate 2 protection, significantly improves the edge quality of the donor substrate 1, optimizes the entire processing flow, improves the production efficiency and reduces the production cost, and has significant technical effects and economic benefits.
[0058] Further, the embodiment also provides a composite substrate which is formed by cracking the bonding layer of the donor substrate 1 obtained by the donor substrate processing method and a receptor substrate along an ion implantation layer after bonding.
[0059] Note that the above merely describes the preferred embodiments of the present application and the principles of the technology applied. Those skilled in the art will understand that the present application is not limited to the specific embodiments described herein, and that various obvious changes, modifications and substitutions can be made by those skilled in the art without departing from the scope of the present application. Therefore, although the present application has been described in detail through the above embodiments, the present application is not limited to the above embodiments, and can include more other equivalent embodiments without departing from the concept of the present application, and the scope of the present application is determined by the scope of the claims.
Claims
1. A method of processing a donor substrate, the method comprising: The method comprises the following steps: S1, performing first chamfering on the edge of the donor substrate (1) to form a first L-shaped chamfer (5); S2, polishing the bonding surface of the donor substrate (1); S3, connecting the cover plate (2) to the bonding surface, the size of the cover plate (2) is reduced by a preset distance based on the size of the bonding surface, so that the part of the bonding surface not covered by the cover plate (2) forms a to-be-chamfered area, and the to-be-chamfered area is arranged around the bonding surface; S4, performing second chamfering on the edge of the donor substrate (1) to remove the to-be-chamfered area and form a second L-shaped chamfer (6), and the second L-shaped chamfer (6) corresponds to the bonding layer; S5, separating the cover plate (2) and the donor substrate (1) to obtain the donor substrate (1) with the bonding layer.
2. The donor substrate processing method according to claim 1, wherein Before the step S1, the donor substrate (1) is bonded to the support substrate (4).
3. The method of claim 2, wherein The donor substrate (1) and the support substrate (4) are made of the same material.
4. The method of claim 1, wherein In the step S1, the depth of the first chamfering is greater than the thickness of the donor substrate (1).
5. The method of claim 1, wherein In the step S3, the cover plate (2) is bonded to the bonding surface by using the adhesive (3).
6. The method of claim 5, wherein The adhesive (3) completely fills the bonding surface.
7. The method of claim 1, wherein In the step S4, the depth of the second chamfering is 0.8-1.2 μm.
8. The method of claim 1, wherein The donor substrate processing method further comprises: S6, peeling off part of the bonding layer from the donor substrate (1); S7, removing the remaining bonding layer on the donor substrate (1); S8, removing the donor substrate (1) with the bonding layer and recycling it into the step S3.
9. The method of claim 1, wherein After the step S2 and before the step S3, an ion implantation layer is formed on the side of the donor substrate (1) close to the bonding surface. The ion implantation layer is located in the bonding layer.
10. A composite substrate, characterized by, The composite substrate is formed by bonding the bonding layer of the donor substrate (1) as claimed in claim 9 and the acceptor substrate, and then cracking along the ion implantation layer.