Method for manufacturing semiconductor substrate
By bonding the first substrate to the second substrate of the multi-layer material and self-stop removal is performed using the difference in the characteristics of the material layer, the material crushing problem caused by mechanical thinning is solved, and efficient transfer of thin-layer material and the manufacturing of semiconductor substrate are achieved.
Patent Information
- Application Number
- CN202410091323.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-01-22
- Publication Date
- 2025-07-22
AI Technical Summary
The prior art can easily lead to the breakage of single crystal silicon material during mechanical thinning, and it is difficult to effectively transfer thin single crystal silicon material.
By bonding the first substrate to the second substrate with a multi-layer material, the self-stop material layer is removed by using the characteristics of different material layers to reduce mechanical thinning time, and the multi-layer material is removed by a combination of dry etching and wet corrosion, retaining the thin top layer material.
The risk of material breakage is reduced, the material transfer efficiency is improved, and the semiconductor substrate with thin thickness can be effectively formed.
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Figure CN120356820A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of semiconductor technology, and in particular, to a method for manufacturing a semiconductor substrate. Background Art
[0002] In the fields of microelectromechanical systems (MEMS) and integrated circuit (IC) manufacturing, sometimes it is necessary to transfer a part of the material layer of a substrate to another substrate to form a new semiconductor substrate.
[0003] For example, a single-crystalline silicon layer with a certain thickness is transferred to a substrate having a recess formed on its surface to form a Cavity Silicon-On-Insulator (CSOI) substrate.
[0004] Generally, the method shown in Figure 1 can be used to form a CSOI substrate. As shown in Figure 1 , this method includes: bonding the surface of a single-crystalline silicon substrate 1 to the surface of a substrate 2 having a recess 21 formed thereon; then, removing a part of the single-crystalline silicon material from the back surface of the single-crystalline silicon substrate 1 by mechanical thinning, and retaining a single-crystalline silicon material 11 with a predetermined thickness; finally, polishing the exposed surface of the remaining single-crystalline silicon material 11 by chemical mechanical polishing (CMP) to form a CSOI substrate 100.
[0005] It should be noted that the above introduction of the technical background is only for the convenience of clearly and completely explaining the technical solution of this application and facilitating the understanding of those skilled in the art. It cannot be considered that the above technical solutions are well known to those skilled in the art just because these solutions are described in the background art part of this application. Summary of the Invention
[0006] The inventors of this application have found that Figure 1 the method shown in
[0007] To solve the above problems or at least similar problems, an embodiment of the present application provides a method for manufacturing a semiconductor substrate. This method bonds a first substrate to a second substrate having multiple layers of materials, and thins the second substrate having multiple layers of materials. Thus, it is possible to utilize the characteristic differences of different material layers to perform a self-stopping material layer removal method, reducing the application time of mechanical thinning and lowering the risk of material breakage. In addition, it is possible to transfer the top layer material with a thin thickness among the multiple layers of materials of the second substrate.
[0008] According to one aspect of an embodiment of the present application, a method for manufacturing a semiconductor substrate is provided. The method includes:
[0009] Bonding the surface of the first substrate to the first surface of the second substrate, wherein the second substrate sequentially includes a top layer material, an intermediate layer material, and a substrate layer material in a direction from the first surface to the second surface; and
[0010] Removing the substrate layer material and the intermediate layer material of the second substrate, and retaining the top layer material, wherein the top layer materials of the first substrate and the second substrate form a semiconductor substrate.
[0011] In at least some embodiments, the method further includes:
[0012] Forming a concave portion on the surface of the first substrate before bonding the first substrate and the second substrate; and
[0013] Performing a thermal oxidation treatment on the first substrate formed with the concave portion.
[0014] In at least some embodiments, removing the substrate layer material of the second substrate includes:
[0015] Thinning the substrate layer material to a first predetermined thickness; and
[0016] Using dry etching to remove the remaining substrate layer material.
[0017] In at least some embodiments, removing the intermediate layer material of the second substrate includes:
[0018] Using wet etching or dry etching to remove the intermediate layer material.
[0019] In at least some embodiments, the intermediate layer material is an oxide, and the substrate layer material is silicon.
[0020] The beneficial effects of the present application are as follows: The method bonds a first substrate to a second substrate with multiple layers of materials, and thins the second substrate with multiple layers of materials. Thus, it is possible to utilize the characteristic differences of different material layers to perform a self-stopping material layer removal method, reducing the application time of mechanical thinning and lowering the risk of material breakage. In addition, it is possible to transfer the top layer material with a thin thickness in the multiple layers of materials of the second substrate.
[0021] Reference is made to the following description and the drawings, which disclose in detail specific embodiments of the present application and indicate the ways in which the principles of the present application can be employed. It should be understood that the embodiments of the present application are not limited thereby in scope. Within the spirit and terms of the appended claims, the embodiments of the present application include many variations, modifications, and equivalents.
[0022] Features described and / or illustrated for one embodiment can be used in the same or similar manner in one or more other embodiments, combined with the features in other embodiments, or substitute for the features in other embodiments.
[0023] It should be emphasized that the term "comprising / including" as used herein refers to the presence of features, whole units, steps, or components, but does not exclude the presence or addition of one or more other features, whole units, steps, or components. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] The accompanying drawings included are used to provide a further understanding of the embodiments of the present application, which form a part of the specification, are used to illustrate the embodiments of the present application, and together with the written description are used to explain the principles of the present application. Obviously, the drawings in the following description are only some embodiments of the present application, and for those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts. In the drawings:
[0025] Figure 1 is a schematic diagram of an existing method for forming a CSOI substrate;
[0026] Figure 2 is a schematic diagram of the method for manufacturing a semiconductor substrate of the present application;
[0027] Figures 3 to 4 is a cross-sectional schematic diagram of the substrate corresponding to each step in the method for manufacturing the semiconductor substrate. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0028] Referring to the accompanying drawings, the foregoing and other features of the present application will become apparent from the following description. In the description and drawings, specific embodiments of the present application are specifically disclosed, which show some embodiments in which the principles of the present application can be adopted. It should be understood that the present application is not limited to the described embodiments. On the contrary, the present application includes all modifications, variations, and equivalents falling within the scope of the appended claims.
[0029] In the description of the embodiments of the present application, for convenience of description, the direction parallel to the surface of the first substrate is referred to as "lateral", and the direction perpendicular to the surface of the first substrate is referred to as "longitudinal". The dimension in the "longitudinal" direction can be referred to as "height" or "thickness". In the "longitudinal" direction, the direction from the back surface to the front surface of the first substrate is referred to as the "up" direction, and the opposite direction to the "up" direction is the "down" direction. The first substrate may have a central axis parallel to the "longitudinal" direction, and the direction around the central axis is referred to as the "circumferential" direction, and the radial direction along the radius of the central axis is referred to as the "radial" direction.
[0030] It should be noted that the above "up" direction and "down" direction are only for convenience of description and do not limit the orientation or posture of the semiconductor substrate of the present application during manufacturing or use.
[0031] Embodiment
[0032] Figure 2 is a schematic diagram of a method for manufacturing a semiconductor substrate according to the present application.
[0033] As Figure 2 shown, the method for manufacturing a semiconductor substrate includes:
[0034] Operation 201: Bond the surface of the first substrate to the first surface of the second substrate, where the second substrate sequentially includes a top layer material, an intermediate layer material, and a substrate layer material in the direction from the first surface to the second surface; and
[0035] Operation 202: Remove the substrate layer material and the intermediate layer material of the second substrate, and retain the top layer material, where the top layer materials of the first substrate and the second substrate form a semiconductor substrate.
[0036] According to an embodiment of the present application, a first substrate is bonded to a second substrate having multiple layers of materials, and the second substrate having multiple layers of materials is thinned. Thus, by utilizing the characteristic differences of different material layers, a self-stopping material layer removal method can be carried out, reducing the application time of mechanical thinning and lowering the risk of breakage of the top layer material. In addition, the thin top layer material in the multiple layers of materials of the second substrate can be transferred to the surface of the first substrate, thereby forming a semiconductor substrate with a thin top layer material. For example, the thickness of the top layer material of the second substrate can be less than 10 micrometers, or the thickness of the top layer material of the second substrate can be other thicknesses greater than or equal to 10 micrometers.
[0037] In the present application, the first substrate can be a substrate commonly used in semiconductor manufacturing processes. For example, the first substrate can be a silicon wafer, a silicon-on-insulator (SOI) wafer, a silicon-germanium wafer, a glass substrate, a sapphire substrate, etc. In an embodiment of the present application, the first substrate being a silicon wafer is taken as an example for illustration. Electronic circuits or micro-mechanical structures, etc. can be formed on the surface or the back surface of the first substrate.
[0038] The intermediate layer material of the second substrate can be different from the top layer material and the bottom layer material. Thus, by utilizing the differences between the bottom layer material and the intermediate layer material, the thinning process for the bottom layer material can be stopped at the intermediate layer material. In addition, by utilizing the differences between the intermediate layer material and the top layer material, the thinning process for the intermediate layer material can be stopped at the top layer material.
[0039] In the present application, the top layer material and the bottom layer material can be the same or different.
[0040] In some embodiments: the intermediate layer material can be an oxide; the bottom layer material can be silicon; the top layer material can include at least one of silicon, germanium, and other semiconductor materials. For example, the top layer material can be silicon, silicon-germanium, germanium, or other semiconductor materials. In a specific example, the second substrate can be a silicon-on-insulator (SOI) wafer, where the bottom layer material is silicon, the intermediate layer material is silicon oxide, and the top layer material is silicon.
[0041] In operation 201, the bonding of the first substrate and the second substrate can be direct bonding, or the first substrate and the second substrate can be bonded through a bonding material. After bonding the first substrate and the second substrate together, heat treatment (such as annealing) can be carried out to improve the bonding quality.
[0042] As Figure 2 shown, the method for manufacturing a semiconductor substrate further includes:
[0043] Operation 203, forming a concave portion on the surface of the first substrate before bonding the first substrate and the second substrate; and
[0044] Operation 204: Perform a thermal oxidation process on the first substrate formed with the concave portion.
[0045] Operation 203 and Operation 204 can be performed before Operation 201.
[0046] In Operation 203, a concave portion can be formed on the surface (e.g., the front side) of the first substrate by using dry etching or other etching methods. In Operation 204, a thermal oxidation process is performed on the first substrate. After the thermal oxidation process, an oxide layer covering the front and back surfaces can be formed on the front and back surfaces of the first substrate, and an oxide layer can also be formed at the bottom and side walls of the concave portion. Through Operation 203, when the first substrate and the second substrate are bonded together, the top layer material of the second substrate and the concave portion enclose a cavity; through Operation 204, the first substrate and the second substrate can be bonded by means of this oxide layer, and in addition, an insulating layer can be formed between the first substrate and the second substrate.
[0047] In Operation 202, the underlying layer material of the second substrate is removed, including:
[0048] Operation 2021: Thin the underlying layer material to a first predetermined thickness;
[0049] Operation 2022: Use dry etching to remove the remaining underlying layer material.
[0050] In Operation 2021, the underlying layer material can be thinned from the surface of the underlying layer material (i.e., the second surface of the second substrate) by using mechanical thinning. For example, the underlying layer material is thinned to a first predetermined thickness so that the remaining thickness of the second substrate is about 250 micrometers. In this way, the remaining second substrate can have sufficient mechanical strength to avoid breakage. In addition, the remaining thickness of the second substrate is not limited to about 250 micrometers, and this thickness can be set based on the lateral dimension of the concave portion. For example, if the lateral dimension of the concave portion is larger, the remaining thickness of the second substrate can be larger, so that it has sufficient mechanical strength and will not be damaged.
[0051] In Operation 2022, the remaining underlying layer material can be removed by using dry etching. For example, methods such as deep reactive ion etching (DRIE) or inductively coupled plasma (ICP) etching are used. This dry etching can have a selectivity characteristic, that is, the etching rate of this dry etching for the underlying layer material is high, but the etching rate for the intermediate layer material is low. Therefore, after the underlying layer material is etched, the etching stops at the intermediate layer material.
[0052] In operation 202, after removing the underlayer material of the second substrate, the intermediate layer material is exposed. Removing the intermediate layer material includes: removing the intermediate layer material using wet etching. For example, if the intermediate layer material is silicon oxide, buffered oxide etchant (BOE) can be used to wet-etch the intermediate layer material. In addition, other types of etchants can also be used. Since the wet etching has a high etching rate for the intermediate layer material and a low etching rate for the top layer material (e.g., silicon), the top layer material can be retained.
[0053] Alternatively, in operation 202, dry etching can also be used to remove the intermediate layer material.
[0054] Next, a manufacturing method of a semiconductor substrate according to the present application will be described with reference to an example.
[0055] Figures 3 to 4 is a cross-sectional schematic view of the substrate corresponding to each step in the manufacturing method of the semiconductor substrate. As Figures 3 to 4 shown, in this example, the manufacturing method of the semiconductor substrate includes:
[0056] 1. As Figure 3 shown, the first substrate 31 is a single-crystalline silicon substrate, and its thickness is, for example, about 720 micrometers. The front surface of the first substrate 31 is polished. The back surface of the first substrate 31 is thinned and polished.
[0057] 2. As Figure 3 shown, dry etching (e.g., deep silicon etching) is performed on the front surface of the first substrate 31, so as to form a recess 311 on the surface of the first substrate 31.
[0058] 3. As Figure 3 shown, the first substrate 31 formed with the recess 311 is subjected to thermal oxidation treatment, so as to form an oxide layer 312 on the front and back surfaces of the first substrate 31. Among them, the oxide layer 312 is also formed at the bottom and side walls of the recess 311.
[0059] 4. As Figure 4 shown, the second substrate 32 is a SOI substrate. The second substrate 32 has a top layer material 321 (e.g., top silicon), an intermediate layer material 322 (e.g., buried oxide layer), and an underlayer material 323 (e.g., substrate silicon). Among them, the thickness of the top layer material 321 is, for example, about 5 micrometers. The surface (i.e., the first surface) of the top layer material 321 of the second substrate 32 is bonded to the front surface of the first substrate 31. This bonding is, for example, direct bonding, and annealing is performed after bonding.
[0060] 5. As Figure 4As shown, the underlying layer material 323 is thinned from the second surface of the second substrate 32, so that the underlying layer material 323 is thinned to the first thickness. For example, this thinning uses a mechanical thinning method; after thinning, the remaining thickness of the second substrate 32 is about 250 microns, for example.
[0061] 6. As Figure 4 As shown, dry etching is performed on the remaining underlying layer material 323 to completely remove the underlying layer material 323. Then, wet etching is performed on the intermediate layer material 322 using BOE to completely remove the intermediate layer material 322, or dry etching is used to completely remove the intermediate layer material 322.
[0062] Thereby, a semiconductor substrate 400 is formed by bonding the top layer material 321 and the first substrate 31 together. In this semiconductor substrate 400, the top layer material 321 is formed above the recess 311 (i.e., the cavity) and the thermal oxide layer. Therefore, this semiconductor substrate 400 is a Cavity Silicon-On-Insulator (CSOI) substrate.
[0063] Through the embodiments of the present application, the first substrate is bonded to the second substrate having multiple material layers, and the second substrate having multiple material layers is thinned. Thereby, it is possible to utilize the characteristic differences of different material layers to perform a self-stopping material layer removal method, reducing the application time of mechanical thinning and reducing the risk of breakage of the top layer material; in addition, it is possible to transfer the top layer material with a small thickness in the multiple material layers of the second substrate to the surface of the first substrate, thereby forming a semiconductor substrate having a thin top layer material. For example, the thickness of the top layer material of the second substrate can be less than 10 microns.
[0064] The above describes the present application in combination with specific implementation manners, but those skilled in the art should understand that these descriptions are exemplary and not a limitation on the protection scope of the present application. Those skilled in the art can make various variations and modifications to the present application according to the spirit and principle of the present application, and these variations and modifications are also within the scope of the present application.
Claims
1. A method of manufacturing a semiconductor substrate, characterized in that, The method includes: bonding the surface of a first substrate to a first surface of a second substrate, wherein the second substrate sequentially includes a top layer material, an intermediate layer material, and a bottom layer material in a direction from the first surface to a second surface; and removing the bottom layer material and the intermediate layer material of the second substrate, and retaining the top layer material, wherein the top layer materials of the first substrate and the second substrate form a semiconductor substrate.
2. The method according to claim 1, wherein The method further includes: forming a recess on the surface of the first substrate before bonding the first substrate and the second substrate; and performing a thermal oxidation treatment on the first substrate having the recess formed thereon.
3. The method according to claim 1, wherein removing the bottom layer material of the second substrate includes: thinning the bottom layer material to a first predetermined thickness; and removing the remaining bottom layer material using dry etching.
4. The method according to claim 3, wherein removing the intermediate layer material of the second substrate includes: removing the intermediate layer material using wet etching or dry etching.
5. The method according to claim 4, wherein the intermediate layer material is an oxide, and the bottom layer material is silicon.