SOI substrate and forming method thereof, and semiconductor structure and forming method thereof
By forming an oxide material barrier layer on the back of the silicon wafer in the SOI substrate formation process, the back damage caused by oxygen ion implantation is solved, and the subsequent process technology is facilitated, meeting the market's demand for semiconductor structure research and development.
Patent Information
- Application Number
- CN202411710913.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-27
- Publication Date
- 2025-03-11
AI Technical Summary
In the existing SOI substrate formation process, it is difficult for the polycrystalline silicon film layer to effectively block oxygen ion implantation, resulting in damage to the back of the silicon wafer, and the subsequent process process is difficult to implement, which is difficult to meet market demand.
A barrier layer including an oxide material is formed on the back side of the silicon wafer, oxygen ion implantation is blocked by the oxide material, the back side of the silicon wafer is protected, and the barrier layer is removed in the subsequent process by selective etching to achieve the formation of the back device structure.
Effectively protect the back of the silicon wafer, avoid damage caused by oxygen ion implantation, and facilitate subsequent implementation of process processes on the back to meet the needs of semiconductor structure research and development.
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Figure CN119601528A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of semiconductor manufacturing technology, and in particular to an SOI substrate and a forming method thereof, a semiconductor structure and a forming method thereof. Background Art
[0002] SOI (Silicon-On-Insulator) substrate is a substrate structure with a buried oxide layer inserted between the top silicon and the bottom silicon. SIMOX (Separation by Implanted Oxygen) technology is a process for forming SOI, which is to implant oxygen ions of a certain energy and dose into a silicon wafer, and then eliminate the lattice damage caused by the oxygen ion implantation process through a subsequent long-term high-temperature treatment process, and at the same time form a continuous buried oxide layer inside the silicon wafer, and the buried oxide layer separates the silicon wafer into a top silicon and a bottom silicon. In the process of oxygen ion implantation, in order to avoid damaging the back of the silicon wafer, it is usually necessary to set a polysilicon film layer on the back of the silicon wafer as a barrier layer for oxygen ion implantation. However, with the exploration and deepening of technical research and the continuous development of the semiconductor industry, the demand for adding processes on the back of the SOI substrate is gradually increasing. The polysilicon film layer is difficult to meet the growing process requirements due to its limited effect in blocking oxygen ion implantation and its subsequent defects such as difficulty in removal.
[0003] Therefore, how to effectively protect the back side of the silicon wafer during the formation of the SOI substrate and facilitate the subsequent implementation of the process technology on the back side of the silicon wafer to meet the market demand for semiconductor structure research and development is a technical problem that needs to be solved urgently. Summary of the invention
[0004] The present invention provides an SOI substrate and a method for forming the same, a semiconductor structure and a method for forming the same, which are used to effectively protect the back side of a silicon wafer during the process of forming the SOI substrate, and facilitate the subsequent implementation of a process on the back side of the silicon wafer to meet the market demand for research and development of semiconductor structures.
[0005] According to some embodiments, the present invention provides a method for forming an SOI substrate, comprising the following steps:
[0006] Providing a silicon wafer, wherein the silicon wafer comprises a front side and a back side that are relatively distributed;
[0007] forming a barrier layer including an oxide material on the back side of the silicon wafer;
[0008] Implanting oxygen ions into the silicon wafer from the front side of the silicon wafer to form a buried oxide layer in the silicon wafer, wherein the silicon wafer above the buried oxide layer serves as top silicon, and the silicon wafer below the buried oxide layer serves as bottom silicon, so as to form an SOI substrate including the top silicon, the buried oxide layer and the bottom silicon;
[0009] The barrier layer is removed.
[0010] In some embodiments, before forming a barrier layer comprising an oxide material on the back side of the silicon wafer, the following steps are further included:
[0011] The front side and the back side of the silicon wafer are polished respectively.
[0012] In some embodiments, the specific steps of forming a barrier layer including an oxide material on the back side of the silicon wafer include:
[0013] An oxide material is deposited on the back side of the silicon wafer to form a deposited oxide layer, and the deposited oxide layer is used as the barrier layer.
[0014] In some embodiments, the oxide material is a silicon dioxide material.
[0015] In some embodiments, the specific steps of forming a barrier layer including an oxide material on the back side of the silicon wafer include:
[0016] Depositing an oxide material on the back side of the silicon wafer to form a deposited oxide layer;
[0017] A polysilicon material is deposited on the back side of the silicon wafer to form a polysilicon layer covering the deposited oxide layer, and the deposited oxide layer and the polysilicon layer are used together as the barrier layer.
[0018] In some embodiments, the specific steps of removing the barrier layer include:
[0019] The barrier layer is removed by a wet etching process to expose the back side of the silicon wafer.
[0020] According to some other embodiments, the present invention further provides an SOI substrate formed by the method for forming the SOI substrate as described above.
[0021] According to some further embodiments, the present invention further provides a method for forming a semiconductor structure, comprising the following steps:
[0022] Providing a silicon wafer, wherein the silicon wafer comprises a front side and a back side that are relatively distributed;
[0023] forming a barrier layer including an oxide material on the back side of the silicon wafer;
[0024] Implanting oxygen ions into the silicon wafer from the front side of the silicon wafer to form a buried oxide layer in the silicon wafer, wherein the silicon wafer above the buried oxide layer serves as top silicon, and the silicon wafer below the buried oxide layer serves as bottom silicon, so as to form an SOI substrate including the top silicon, the buried oxide layer and the bottom silicon;
[0025] removing the barrier layer to expose the underlying silicon;
[0026] A backside device structure is formed on a surface of the bottom silicon away from the buried oxide layer.
[0027] In some embodiments, the oxide material is a silicon dioxide material.
[0028] According to some further embodiments, the present invention further provides a semiconductor structure formed by the method for forming a semiconductor structure as described above.
[0029] The SOI substrate and its forming method, the semiconductor structure and its forming method provided by the present invention form a barrier layer including an oxide material as a back sealing structure on the back side of the silicon wafer before oxygen ions are injected into the silicon wafer. On the one hand, the oxide material can better block the damage to the back side of the silicon wafer during the oxygen ion injection process; on the other hand, since the oxide material has a high etching selectivity ratio with the silicon wafer, it is convenient to avoid etching damage to the back side of the silicon wafer while fully removing the barrier layer, ensuring that a process can be implemented on the back side of the silicon wafer to form a back device structure, thereby meeting the market demand for semiconductor structure research and development. BRIEF DESCRIPTION OF THE DRAWINGS
[0030] Figure 1 is a flow chart of a method for forming an SOI substrate in a specific embodiment of the present invention;
[0031] Figure 2 is a schematic diagram of the structure after a barrier layer is formed on the back side of a silicon wafer in a specific embodiment of the present invention;
[0032] Figure 3 is a schematic structural diagram of the process of injecting oxygen ions into the front side of a silicon wafer in a specific embodiment of the present invention;
[0033] Figure 4 is a schematic diagram of the structure after a buried oxide layer is formed in a silicon wafer in a specific embodiment of the present invention;
[0034] Figure 5 is a schematic diagram of the structure after the barrier layer is removed in a specific embodiment of the present invention;
[0035] Figure 6 It is a flow chart of a method for forming a semiconductor structure in a specific embodiment of the present invention. DETAILED DESCRIPTION
[0036] The specific implementation methods of the SOI substrate and the method for forming the same, the semiconductor structure and the method for forming the same provided by the present invention are described in detail below with reference to the accompanying drawings.
[0037] This specific embodiment provides a method for forming an SOI substrate. Figure 1 FIG. 1 is a flow chart of a method for forming an SOI substrate in a specific embodiment of the present invention. Figure 1 As shown, the method for forming the SOI substrate comprises the following steps:
[0038] Step S11, providing a silicon wafer, wherein the silicon wafer comprises a front side and a back side that are relatively distributed;
[0039] Step S12, forming a barrier layer including an oxide material on the back side of the silicon wafer;
[0040] Step S13, implanting oxygen ions into the silicon wafer from the front side of the silicon wafer to form a buried oxide layer in the silicon wafer, wherein the silicon wafer above the buried oxide layer serves as a top silicon layer, and the silicon wafer below the buried oxide layer serves as a bottom silicon layer, so as to form an SOI substrate including the top silicon layer, the buried oxide layer and the bottom silicon layer;
[0041] Step S14, removing the barrier layer.
[0042] Figure 2 2 is a schematic diagram of a structure after a barrier layer is formed on the back side of a silicon wafer in a specific embodiment of the present invention. In some embodiments, before a barrier layer 21 including an oxide material is formed on the back side 202 of the silicon wafer 20, the following steps are also included:
[0043] The front side 201 and the back side 202 of the silicon wafer 20 are polished respectively.
[0044] Specifically, if Figure 2 As shown, the silicon wafer 20 includes a front side and a back side that are relatively distributed along a first direction D1. Before forming the barrier layer 21 on the back side 202 of the silicon wafer 20, the front side 201 and the back side 202 of the silicon wafer 20 are polished respectively to form a double-sided polished wafer, thereby removing the natural oxide layer on the surface of the silicon wafer 20 (including the front side 201 and the back side 202 of the silicon wafer 20) and improving the flatness of the surface of the silicon wafer 20, which is convenient for the implementation of subsequent processes.
[0045] In some embodiments, the specific steps of forming the barrier layer 21 including an oxide material on the back side 202 of the silicon wafer 20 include:
[0046] An oxide material is deposited on the back side 202 of the silicon wafer 20 to form a deposited oxide layer, and the deposited oxide layer is used as the barrier layer 21 .
[0047] In some embodiments, the oxide material is a silicon dioxide material.
[0048] For example, a low-temperature deposition process can be used to deposit silicon dioxide material on the back side 202 of the silicon wafer 20 to form the deposited oxide layer that continuously covers the entire back side of the silicon wafer 20, and the deposited oxide layer is used as the barrier layer 21. By using silicon dioxide material as the barrier layer 21, the back side 202 of the silicon wafer 20 and the oxygen ions in the ion implantation process can be better isolated, and oxygen ions are prevented from entering from the back side 202 of the silicon wafer 20, thereby effectively protecting the back side of the silicon wafer 20. At the same time, silicon dioxide has a high etching selectivity ratio with silicon, which facilitates the subsequent removal of the barrier layer 21 by a selective etching process, ensuring that the process can be implemented on the back side of the silicon wafer to form a back device structure, thereby meeting the market demand for semiconductor structure research and development.
[0049] In some other embodiments, the specific steps of forming a barrier layer including an oxide material on the back side 202 of the silicon wafer 20 include:
[0050] Depositing an oxide material on the back side 202 of the silicon wafer 20 to form a deposited oxide layer;
[0051] A polysilicon material is deposited on the back side 202 of the silicon wafer 20 to form a polysilicon layer covering the deposited oxide layer, and the deposited oxide layer and the polysilicon layer are used together as the barrier layer 21 .
[0052] Specifically, the barrier layer 21 can be a double-layer structure. For example, the barrier layer 21 can include the deposited oxide layer covering the back side 202 of the silicon wafer 20 and the polycrystalline silicon layer covering the surface of the deposited oxide layer away from the silicon wafer 20, so that the back side 202 of the silicon wafer 20 can be sealed by the deposited oxide layer, and the back side 202 of the silicon wafer 20 can be protected by utilizing the impurity absorption characteristics of the polycrystalline silicon. The synergistic effect of the two aspects can better protect the back side 202 of the silicon wafer 20.
[0053] In some embodiments, the specific steps of removing the barrier layer 21 include:
[0054] The barrier layer 21 is removed by a wet etching process to expose the back side of the silicon wafer.
[0055] Figure 3 is a schematic diagram of the structure when oxygen ions are injected into the front side of a silicon wafer in a specific embodiment of the present invention, Figure 4 is a schematic diagram of the structure after a buried oxide layer is formed in a silicon wafer in a specific embodiment of the present invention, Figure 5 2 is a schematic diagram of a structure after removing the barrier layer in a specific embodiment of the present invention. For example, after forming the barrier layer 21 on the back side 202 of the silicon wafer 20, oxygen ions are implanted into the interior of the silicon wafer 20 from the front side 201 of the silicon wafer 20 along the first direction D1, as shown in FIG. Figure 3 As shown. Among them, Figure 3 The solid arrow in the figure indicates the implantation direction of the oxygen ions. After the oxygen ions are implanted into the silicon wafer 20, the silicon wafer is subjected to a high temperature annealing process to form the buried oxide layer 40 which is continuously distributed at least along the second direction D2 and is made of silicon dioxide inside the silicon wafer 20, as shown in FIG. Figure 4 The silicon wafer 20 above the buried oxide layer 40 is used as the top silicon 41, and the silicon wafer 20 below the buried oxide layer 40 is used as the bottom silicon 42, so as to form an SOI substrate including the top silicon 41, the buried oxide layer 40 and the bottom silicon 42. The second direction D2 is parallel to the front side 201 of the silicon wafer 20.
[0056] After forming the SOI substrate, a wet etchant having a high etching selectivity ratio between the barrier layer 21 and the silicon wafer 20 may be used to etch away the entire barrier layer 21 to expose the underlying silicon 42. Figure 5 In one example, the wet etchant may be hydrofluoric acid.
[0057] This specific embodiment also provides an SOI substrate, which is formed by the method for forming the SOI substrate as described above. Figure 1-Figure 5 The structure of the SOI substrate can be found in Figure 5 .
[0058] This specific embodiment also provides a method for forming a semiconductor structure. Figure 6 is a flow chart of a method for forming a semiconductor structure in a specific embodiment of the present invention. The method for forming an SOI substrate during the formation of the semiconductor structure can be found in Figure 1-Figure 5 .like Figure 1-Figure 6 As shown, the method for forming the semiconductor structure comprises the following steps:
[0059] Step S61, providing a silicon wafer 20, wherein the silicon wafer 20 includes a front side 201 and a back side 202 that are relatively distributed;
[0060] Step S62, forming a barrier layer 21 including an oxide material on the back side 202 of the silicon wafer 20;
[0061] Step S63, oxygen ions are implanted into the silicon wafer 20 from the front side 201 of the silicon wafer 20 to form a buried oxide layer 40 in the silicon wafer 20, the silicon wafer 20 above the buried oxide layer 40 serves as a top silicon layer 41, and the silicon wafer 20 below the buried oxide layer 40 serves as a bottom silicon layer 42, so as to form an SOI substrate including the top silicon layer 41, the buried oxide layer 40 and the bottom silicon layer 42;
[0062] Step S64, removing the barrier layer 21 to expose the bottom silicon 42;
[0063] Step S65 , forming a backside device structure on a surface of the bottom silicon 42 away from the buried oxide layer 40 .
[0064] In some embodiments, the oxide material is a silicon dioxide material.
[0065] This specific embodiment also provides a semiconductor structure, which is formed by the semiconductor structure forming method as described above. Figure 6 .
[0066] The SOI substrate and its formation method, the semiconductor structure and its formation method provided in this specific embodiment, before oxygen ions are injected into the silicon wafer, a barrier layer including an oxide material is formed on the back side of the silicon wafer as a back sealing structure. On the one hand, the oxide material can better block the damage to the back side of the silicon wafer during the oxygen ion injection process; on the other hand, due to the high etching selectivity between the oxide material and the silicon wafer, it is convenient to avoid etching damage to the back side of the silicon wafer while fully removing the barrier layer, ensuring that a process can be implemented on the back side of the silicon wafer to form a back device structure in the future, thereby meeting the market demand for semiconductor structure research and development.
[0067] The above is only a preferred embodiment of the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.
Claims
1. A method for forming an SOI substrate, characterized in that: The steps include: Providing a silicon wafer, wherein the silicon wafer comprises a front side and a back side that are relatively distributed; forming a barrier layer including an oxide material on the back side of the silicon wafer; Implanting oxygen ions into the silicon wafer from the front side of the silicon wafer to form a buried oxide layer in the silicon wafer, wherein the silicon wafer above the buried oxide layer serves as top silicon, and the silicon wafer below the buried oxide layer serves as bottom silicon, so as to form an SOI substrate including the top silicon, the buried oxide layer and the bottom silicon; The barrier layer is removed.
2. The method for forming an SOI substrate according to claim 1, characterized in that: Before forming a barrier layer comprising an oxide material on the back side of the silicon wafer, the method further comprises the following steps: The front side and the back side of the silicon wafer are polished respectively.
3. The method for forming an SOI substrate according to claim 1, characterized in that: The specific steps of forming a barrier layer including an oxide material on the back side of the silicon wafer include: An oxide material is deposited on the back side of the silicon wafer to form a deposited oxide layer, and the deposited oxide layer is used as the barrier layer.
4. The method for forming an SOI substrate according to claim 1, characterized in that: The oxide material is silicon dioxide material.
5. The method for forming an SOI substrate according to claim 1, characterized in that: The specific steps of forming a barrier layer including an oxide material on the back side of the silicon wafer include: Depositing an oxide material on the back side of the silicon wafer to form a deposited oxide layer; A polysilicon material is deposited on the back side of the silicon wafer to form a polysilicon layer covering the deposited oxide layer, and the deposited oxide layer and the polysilicon layer are used together as the barrier layer.
6. The method for forming an SOI substrate according to claim 4, characterized in that: The specific steps of removing the barrier layer include: The barrier layer is removed by a wet etching process to expose the back side of the silicon wafer.
7. A SOI substrate, characterized in that: The SOI substrate is formed by the method for forming the SOI substrate as claimed in claim 1.
8. A method for forming a semiconductor structure, characterized in that: The steps include: Providing a silicon wafer, wherein the silicon wafer comprises a front side and a back side that are relatively distributed; forming a barrier layer including an oxide material on the back side of the silicon wafer; Implanting oxygen ions into the silicon wafer from the front side of the silicon wafer to form a buried oxide layer in the silicon wafer, wherein the silicon wafer above the buried oxide layer serves as top silicon, and the silicon wafer below the buried oxide layer serves as bottom silicon, so as to form an SOI substrate including the top silicon, the buried oxide layer and the bottom silicon; removing the barrier layer to expose the underlying silicon; A backside device structure is formed on a surface of the bottom silicon away from the buried oxide layer.
9. The method for forming a semiconductor structure according to claim 8, characterized in that: The oxide material is silicon dioxide material.
10. A semiconductor structure, characterized in that: The semiconductor structure is formed by the method for forming the semiconductor structure as claimed in claim 8.