Bonding method and method for manufacturing SOI substrate

Abstract

This application provides a bonding method and a method for manufacturing an SOI substrate. The bonding method includes the steps of providing a first silicon substrate and a second silicon substrate; performing an activation treatment on the surface of the first silicon substrate and / or the second silicon substrate to adsorb -OH groups onto the surface; temporarily bonding the first silicon substrate and the second silicon substrate to form a composite substrate; and heating the composite substrate after temporary bonding, maintaining the temperature for a predetermined time, and preserving and dehydrating the bonding interface. In this application, the van der Waals forces at the interface are converted into chemical bonding forces using the activation and preservation method, thereby increasing the bonding interface strength and reducing the width of the unbonded region. By applying this to the field of SOI substrate manufacturing, a better support environment for the delamination process can be provided.

Description

Technical Field

[0001] Cross-reference to Related Applications This application claims priority to Chinese Patent Application No. 202311629938.5, titled "Bonding Method and Method for Manufacturing SOI Substrate", filed on November 30, 2023, the content of which is hereby incorporated by reference in its entirety into this application. This application relates to the field of semiconductor processes, and particularly to a bonding method and a method for manufacturing an SOI substrate.

Background Art

[0002] In the semiconductor field, there already exists a low-temperature temporary bonding technology for obtaining an SOI substrate by directly peeling a bonded wafer from a hydrogen implantation surface after high-temperature annealing. However, in this process flow, a wide unbonded floating region remains at the SOI edge after peeling. Therefore, how to improve the bonding process and reduce the width of the unbonded region at the SOI edge is an issue to be solved in the prior art.

Summary of the Invention

[0003] The technical problem to be solved by this application is to provide a bonding method and a method for manufacturing an SOI substrate that can reduce the width of the unbonded region at the edge in the bonding process.

[0004] To solve the above problems, an embodiment of this application provides a bonding method. This method includes the steps of providing a first silicon substrate and a second silicon substrate, performing an activation treatment on the surface of the first silicon substrate and / or the second silicon substrate to adsorb -OH groups on its surface, temporarily bonding the first silicon substrate and the second silicon substrate to form a composite substrate, and heating the composite substrate after temporary bonding, maintaining it for a predetermined time, and keeping the bonding interface warm to dehydrate.

[0005] Optionally, the composite substrate after temporary bonding is heated to 60 - 120°C.

[0006] Optionally, the predetermined time is 3 to 8 hours.

[0007] Optionally, the surfaces of the first silicon substrate and the second silicon substrate are subjected to activation treatment.

[0008] Optionally, at least one surface of the first silicon substrate and the second silicon substrate has an oxide layer.

[0009] To solve the above problems, embodiments of this application further provide a method for manufacturing an SOI substrate. This method includes the steps of: providing a first silicon substrate and a second silicon substrate; performing ion implantation on the first silicon substrate to form a device layer; forming an oxide layer on the surface of the first silicon substrate and / or the second silicon substrate; performing an activation treatment on the surface of the first silicon substrate and / or the second silicon substrate to adsorb -OH groups on its surface; temporarily joining the first silicon substrate and the second silicon substrate to form a composite substrate; and heating the composite substrate after temporary joining, maintaining the heat for a predetermined time, and preserving the bonding interface to dehydrate it.

[0010] Optionally, the composite substrate is heated to 60-120°C after temporary bonding.

[0011] Optionally, the predetermined time is 3 to 8 hours.

[0012] Optionally, the surfaces of the first silicon substrate and the second silicon substrate are subjected to activation treatment.

[0013] Optionally, an oxide layer is formed on the surfaces of both the first silicon substrate and the second silicon substrate.

[0014] This application describes a method of converting van der Waals forces at the interface into chemical bonding forces using activation and heat retention, thereby increasing the strength of the bonding interface and reducing the width of the unbonded region. Applying this to the field of SOI substrate manufacturing can provide a better support environment for the delamination process. [Brief explanation of the drawing]

[0015] [Figure 1] A schematic diagram of the steps for implementing one specific embodiment of the joining method described in this application is shown. [Figure 2] A diagram illustrating the principle of one specific embodiment of the joining method described in this application is shown. [Figure 3] This diagram shows a schematic representation of the steps of one specific embodiment of the SOI substrate manufacturing method described in this application. [Modes for carrying out the invention]

[0016] Specific embodiments of the bonding method and SOI substrate manufacturing method provided in this application will be described in detail below with reference to the attached drawings.

[0017] Figure 1 shows a schematic diagram of the steps of an implementation of a specific embodiment of the bonding method described in this application, and includes: step S10 of providing a first silicon substrate and a second silicon substrate; step S11 of performing an activation treatment on the surface of the first silicon substrate and / or the second silicon substrate to adsorb -OH groups on the surface; step S12 of temporarily bonding the first silicon substrate and the second silicon substrate to form a composite substrate; and step S13 of heating the composite substrate after temporary bonding, maintaining the temperature for a predetermined time, and preserving the bonding interface and dehydrating it.

[0018] Specifically, in step S11, the surfaces of the first silicon substrate and / or the second silicon substrate are subjected to an activation treatment to adsorb -OH groups onto their surfaces. In this step, both the first silicon substrate and the second silicon substrate are subjected to the activation treatment. Furthermore, the first silicon substrate and the second silicon substrate may have an oxide layer on at least one of their surfaces. Regardless of the presence or absence of an oxide layer, the surfaces have silicon atoms and therefore do not affect the adsorption of -OH groups onto the silicon on the surface.

[0019] In step S12, the first silicon substrate and the second silicon substrate are temporarily joined to form a composite substrate. The environment during joining must be extremely clean, free from particle and metal contamination, and the joining wave requires a certain conduction time.

[0020] In step S13, the composite substrate after temporary bonding is heated and maintained for a predetermined time to keep the bonding interface warm and dehydrate it. This step can be performed by using a constant temperature and humidity insulated box to keep the bonded wafer (i.e., the composite substrate after temporary bonding) warm at 60-120°C for 3-8 hours for dehydration. Intermolecular forces (van der Waals forces) gradually form chemical forces (chemical bonds), strengthening the bonding force. The reaction equation on the surface is as follows: Si-OH+HO-Si=Si-O-Si+H2O

[0021] Figure 2 shows a schematic diagram illustrating the principle of the above reaction at the interface.

[0022] After bonding, water can be evaporated from the edges of the substrate by heating, improving the bonding strength at the edges and reducing the width of the unbonded area at the edges. Experiments have shown that the above method can reduce the width of the unbonded area at the edges from 3 mm to 1.5 mm or less.

[0023] FIG. 3 shows a schematic diagram of the implementation steps of a specific embodiment of the method for manufacturing an SOI substrate described in the present application, including step S20 of providing a first silicon substrate and a second silicon substrate, step S21 of performing ion implantation on the first silicon substrate to form a device layer, step S22 of forming an oxide layer on the surface of the first silicon substrate and / or the second silicon substrate, step S23 of performing an activation treatment on the surface of the first silicon substrate and / or the second silicon substrate to adsorb -OH groups on the surface, step S24 of temporarily bonding the first silicon substrate and the second silicon substrate to form a composite substrate, and step S25 of heating the composite substrate after temporary bonding, maintaining it for a predetermined time, and keeping the bonding interface warm and dehydrating.

[0024] Specifically, the ion implantation in step S21 can inject either H, He, or a combination thereof to form a foaming layer, thereby defining the device layer.

[0025] In step S22, an oxide layer is formed on the surface of the first silicon substrate and / or the second silicon substrate. Since the oxide layer serves to provide a buried oxide layer for the SOI substrate, an oxide layer may be formed on the surface of either the first silicon substrate or the second silicon substrate, or simultaneously.

[0026] In step S23, an activation treatment is performed on the surface of the first silicon substrate and / or the second silicon substrate to adsorb -OH groups on the surface. In this step, the activation treatment is performed on both the first silicon substrate and the second silicon substrate. Also, regardless of the presence or absence of an oxide layer on the surface of the first silicon substrate and the second silicon substrate, since the surface has silicon atoms, it does not affect the adsorption of -OH groups on the silicon on the surface.

[0027] In step S25, the composite substrate after temporary bonding is heated and maintained for a predetermined time to keep the bonding interface warm and dehydrate it. This step can be performed by using a constant temperature and humidity insulated box to keep the bonded wafer (i.e., the composite substrate after temporary bonding) warm at 60-120°C for 3-8 hours for dehydration. Intermolecular forces (van der Waals forces) gradually form chemical forces (chemical bonds), strengthening the bonding force. The reaction equation on the surface is as follows: Si-OH+HO-Si=Si-O-Si+H2O

[0028] Figure 2 shows a schematic diagram illustrating the principle of the above reaction at the interface.

[0029] At the edges of the bonded substrate, water can be evaporated by heating, improving the bond strength at the edges, reducing the width of the unbonded area at the edges, and providing a more effective support environment for subsequent delamination of the substrate from the foam layer. Experiments have shown that the above method can reduce the width of the unbonded area at the edges from 3 mm to 1.5 mm or less.

[0030] After the above steps are performed, it is necessary to further peel the first silicon substrate from the foamed layer position by an annealing peeling step to form an SOI substrate. By performing a heat retention step, the width of the unbonded area at the edge is reduced, so that the peeling in this step can be performed more smoothly.

[0031] The foregoing are merely preferred embodiments of the present application, and it will be apparent to those skilled in the art that various improvements or modifications can be made without departing from the principles of the present application, and that these improvements or modifications are also included within the scope of protection of the present application.

Claims

1. The steps include providing a first silicon substrate and a second silicon substrate, The steps include: performing an activation treatment on the surface of the first silicon substrate and / or the second silicon substrate to adsorb -OH groups onto its surface; The steps include: temporarily joining the first silicon substrate and the second silicon substrate to form a composite substrate; The steps include heating the composite substrate after temporary bonding, maintaining the temperature for a predetermined time, and keeping the bonding interface warm and dehydrating it, A joining method that includes [a specific type of joining].

2. The method according to claim 1, characterized in that the composite substrate after temporary bonding is heated to 60 to 120°C.

3. The method according to claim 1, characterized in that the predetermined time is 3 to 8 hours.

4. The method according to claim 1, characterized in that an activation treatment is performed on the surfaces of both the first silicon substrate and the second silicon substrate.

5. The method according to claim 1, characterized in that at least one surface of the first silicon substrate and the second silicon substrate has an oxide layer.

6. The steps include providing a first silicon substrate and a second silicon substrate, The steps include: performing ion implantation on the first silicon substrate to form a device layer; The steps include forming an oxide layer on the surface of the first silicon substrate and / or the second silicon substrate, The steps include: performing an activation treatment on the surface of the first silicon substrate and / or the second silicon substrate to adsorb -OH groups onto its surface; The steps include: temporarily joining the first silicon substrate and the second silicon substrate to form a composite substrate; The steps include heating the composite substrate after temporary bonding, maintaining the temperature for a predetermined time, and keeping the bonding interface warm and dehydrating it, A method for manufacturing an SOI substrate that includes [a specific component].

7. The method according to 6, characterized in that the composite substrate after temporary bonding is heated to 60 to 120°C.

8. The method according to claim 6, characterized in that the predetermined time is 3 to 8 hours.

9. The method according to 6, characterized in that an activation treatment is performed on the surfaces of both the first silicon substrate and the second silicon substrate.

10. The method according to 6, characterized in that an oxide layer is formed on the surface of both the first silicon substrate and the second silicon substrate.

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