A sidewall etching method and sidewall
By introducing a sacrificial layer to protect the oxide layer before sidewall etching and increasing the over-etching amount to remove the pins, the problem of balancing the pins and oxide layer in sidewall etching is solved, resulting in better chip performance and gate angle control.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHANGHAI INTEGRATED CIRCUIT EQUIPMENT & MATERIALS INDUSTRY INNOVATION CENTER CO LTD
- Filing Date
- 2024-12-18
- Publication Date
- 2026-06-19
AI Technical Summary
In the 28HK product, the sidewall etching process cannot effectively remove the base plate and the protective oxide layer at the same time, which affects the chip performance and the gate angle cannot be independently controlled.
A sacrificial layer is introduced before sidewall etching. The base is removed by appropriately increasing the over-etching amount, while protecting the oxide layer. The sacrificial layer is then removed to form the sidewall.
It achieves effective removal of the base plate without loss of oxide layer during sidewall etching, and can fine-tune the gate angle, thereby improving chip performance.
Smart Images
Figure CN122248775A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of semiconductor technology, and in particular to a sidewall etching method and a sidewall. Background Technology
[0002] In 28HK (High-k, high dielectric constant insulating layer) products, Spacer 1 (sidewall) limits the lateral and longitudinal distance between the LDD (lightly doped drain) and the gate, thereby controlling the gate-drain capacitance. Sidewall etching mainly involves two steps: main etching and over-etching. Main etching is the etching of the sidewall material layer, and over-etching is the finishing of the sidewall base.
[0003] like Figure 1 and Figure 2 As shown, in current sidewall etching, it is impossible to completely balance the needs of the base plate 41 and the oxide layer 2. Insufficient OE (Overetch) cannot completely remove the base plate 41, while excessive OE leads to excessive loss of the oxide layer 2. Both factors negatively impact the final chip performance. Furthermore, since the OE amount cannot be arbitrarily adjusted, the Gate ANG (gate angle) can currently only be inherited from the previous layer and cannot be individually controlled at the current station. Therefore, a sidewall etching method is needed to solve the trade-off problem between the base plate and oxide layer in traditional sidewall etching. Summary of the Invention
[0004] The purpose of this application is to provide a sidewall etching method and a sidewall. By introducing a sacrificial layer, the amount of over-etching can be appropriately increased during the sidewall etching process, which can remove the base and ensure that the loss of oxide layer does not increase.
[0005] To achieve the above objectives, this application provides a sidewall etching method, comprising:
[0006] An initial structure is formed on a substrate, the initial structure including an oxide layer formed on the surface of the substrate and at least two gates formed on the surface of the oxide layer;
[0007] A sacrificial layer is deposited such that the sacrificial layer at least covers the oxide layer between adjacent gates;
[0008] A sidewall material layer is deposited, the sidewall material layer at least covering the gate sidewall and the sacrificial layer between adjacent gates;
[0009] The sidewall material layer is etched to remove the sidewall material layer on the top surface of the gate, and the sidewall material layer on the side surface of the gate forms a base.
[0010] The over-etching amount is determined based on the height of the base, and the base is over-etched according to the over-etching amount to remove the base;
[0011] After removing the base, the sacrificial layer is removed to obtain the sidewall.
[0012] Optionally, the deposition of the sacrificial layer, such that the sacrificial layer at least covers the oxide layer between adjacent gates, includes:
[0013] The sacrificial layer is deposited by chemical vapor deposition, so that the sacrificial layer covers the oxide layer between adjacent gates and the top surface of the gate.
[0014] Optionally, the sacrificial layer is a metal oxide layer.
[0015] Optionally, removing the sacrificial layer includes:
[0016] The sacrificial layer is removed by wet etching.
[0017] Optionally, the removal of the sacrificial layer by wet etching includes:
[0018] The sacrificial layer is removed by wet etching using a wet etching solution comprising HCl, H2O2, and H2O.
[0019] Optionally, removing the sacrificial layer includes:
[0020] The sacrificial layer is removed by dry etching.
[0021] Optionally, the removal of the sacrificial layer by dry etching includes:
[0022] The sacrificial layer is removed by dry etching using reactive gases, including Cl2 and BCl3.
[0023] Optionally, the sidewall material layer is a SiN layer.
[0024] Optionally, after removing the base plate and before removing the sacrificial layer, the process further includes:
[0025] The over-etching amount is determined based on the target gate angle, and the sidewall material layer on the side of the gate is over-etched based on the over-etching amount to obtain the target gate angle.
[0026] To achieve the above objectives, this application also provides a sidewall, comprising: a sidewall prepared by the sidewall etching method described above.
[0027] This application provides a sidewall etching method, comprising: forming an initial structure on a substrate, the initial structure including an oxide layer formed on the surface of the substrate and at least two gates formed on the surface of the oxide layer; depositing a sacrificial layer such that the sacrificial layer at least covers the oxide layer between adjacent gates; depositing a sidewall material layer such that the sidewall material layer at least covers the sidewall of the gate and the sacrificial layer between adjacent gates; performing a main etching on the sidewall material layer to remove the sidewall material layer on the top surface of the gate and to form a base plate on the sidewall of the gate; determining an over-etching amount based on the height of the base plate, and performing over-etching on the base plate based on the over-etching amount to remove the base plate; after removing the base plate, removing the sacrificial layer to obtain a sidewall.
[0028] Obviously, because this application deposits a sacrificial layer before depositing the sidewall material layer to protect the oxide layer beneath the substrate, the substrate can be better removed during sidewall etching by appropriately increasing the over-etching amount. Simultaneously, the presence of the sacrificial layer does not affect the oxide layer. This application also provides a sidewall prepared using the sidewall etching method provided in this application, which, compared to traditional sidewalls, does not have a substrate and does not lose the oxide layer. Attached Figure Description
[0029] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.
[0030] Figure 1 This is a schematic diagram of the structure before etching during the traditional sidewall formation process;
[0031] Figure 2 This is a schematic diagram of the structure after the main etching during the traditional sidewall formation process.
[0032] Figure 3 A flowchart of a sidewall etching method provided in this application embodiment;
[0033] Figure 4 This is a schematic diagram of the structure before sidewall etching provided in an embodiment of this application;
[0034] Figure 5 This is a schematic diagram of the structure of the sidewall after etching, provided in an embodiment of this application.
[0035] The annotations in the attached figures are explained as follows:
[0036] 1-Substrate; 11-P-well; 12-N-well; 2-Oxide layer; 3-Gate; 4-Sidewall material layer; 41-Pin; 5-Sacrificial layer. Detailed Implementation
[0037] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0038] Please refer to Figure 3 , Figure 3 A flowchart of a sidewall etching method provided in this application embodiment, the method may include:
[0039] S100: An initial structure is formed on a substrate, the initial structure including an oxide layer formed on the surface of the substrate and at least two gates formed on the surface of the oxide layer.
[0040] It should be noted that before depositing the sacrificial layer 5 on the surface of substrate 1, an oxide layer 2 is pre-formed on the surface of substrate 1; at least two gates 3 are formed on the surface of oxide layer 2 facing away from substrate 1. Substrate 1 may be, but is not limited to, a silicon substrate 1. Gate 3 may include, but is not limited to, a polysilicon layer, a silicon nitride layer, and a silicon oxide layer sequentially disposed along the thickness direction; correspondingly, forming at least two gates 3 on the surface of oxide layer 2 facing away from substrate 1 may include: sequentially forming a polysilicon layer, a silicon nitride layer, and a silicon oxide layer along the thickness direction on the surface of oxide layer 2 facing away from substrate 1; after forming the polysilicon layer, silicon nitride layer, and silicon oxide layer, performing patterning processing to form at least two gates 3.
[0041] Furthermore, before forming oxide layer 2 on the surface of substrate 1, well regions can be formed in substrate 1, including P-well 11 and N-well 12, with gate 3 corresponding to the well regions one-to-one. S101: Deposit a sacrificial layer such that the sacrificial layer at least covers the oxide layer between adjacent gates.
[0042] This embodiment does not limit the specific method of depositing the sacrificial layer 5, as long as the sacrificial layer 5 can cover the oxide layer 2 between adjacent gates 3. For example, the sacrificial layer 5 can be deposited by chemical vapor deposition so that the sacrificial layer 5 covers the oxide layer 2 between adjacent gates 3 and the top surface of the gate 3.
[0043] This embodiment does not limit the specific type of the sacrificial layer 5, as long as it can prevent the oxide layer 2 covering the sacrificial layer 5 from being etched away. For example, the sacrificial layer 5 can be a metal oxide layer, and the metal oxide layer can be an Al2O3 layer.
[0044] S102: Deposit a sidewall material layer, the sidewall material layer covering at least the gate sidewall and the sacrificial layer between adjacent gates.
[0045] This embodiment does not limit the specific type of sidewall material layer 4. Sidewall material layer 4 can be, but is not limited to, a SiN layer. It should be noted that when the sacrificial layer 5 is a metal oxide layer, since SiN has a very high etching selectivity for the sacrificial layer 5, the sacrificial layer 5 will not be lost. Therefore, the oxide layer 2 covering the sacrificial layer 5 can be avoided from being etched away, thereby reducing the loss of oxide layer 2.
[0046] It should be noted that the sidewall material layer 4 deposited in this embodiment at least covers the side of the gate 3 and the sacrificial layer 5 between adjacent gates 3. When the sacrificial layer 5 is deposited on the top surface of the gate 3, the sidewall material layer 4 also covers the sacrificial layer 5 on the top surface of the gate 3, or when the sacrificial layer 5 is not deposited on the top surface of the gate 3, the sidewall material layer 4 also covers the top surface of the gate 3.
[0047] S103: Perform main etching on the sidewall material layer to remove the sidewall material layer on the top surface of the gate and form a base plate on the sidewall material layer of the gate.
[0048] It should be noted that during the main etching in this embodiment, the sidewall material layer 4 on the top surface of the gate 3 is removed, while the sidewall material layer 4 on the side surface of the gate 3 is retained, and the sidewall material layer 4 on the side surface of the gate 3 forms a base.
[0049] S104: Determine the over-etching amount based on the height of the base plate, and perform over-etching on the base plate according to the over-etching amount to remove the base plate.
[0050] It should be noted that the over-etching amount determined based on the height of the base in this embodiment is the maximum over-etching amount that can ensure the complete removal of the base. By over-etching the base according to this over-etching amount, the base can be completely removed. However, in traditional sidewall etching, excessive over-etching can lead to excessive loss of oxide layer 2. Therefore, the over-etching amount in this step is usually not set very high, which may result in the base not being completely removed.
[0051] S105: After removing the base, remove the sacrificial layer to obtain the sidewall.
[0052] It should be noted that in this embodiment, the final sidewall only includes the sidewall material layer 4 covering the side of the gate 3, and does not have a base.
[0053] This embodiment does not limit the specific method of removing the sacrificial layer 5, as long as it can be removed. For example, the following methods can be used:
[0054] (1) The sacrificial layer 5 is removed by wet etching. This embodiment does not limit the specific method of wet etching. The sacrificial layer 5 can be removed by wet etching using a wet etching solution, including HCl, H2O2 and H2O.
[0055] (2) The sacrificial layer 5 is removed by dry etching. This embodiment does not limit the specific method of dry etching, and the sacrificial layer 5 can be removed by dry etching using reactive gases, including Cl2 and BCl3.
[0056] Furthermore, in this embodiment, after removing the base plate and before removing the sacrificial layer 5, the process may further include:
[0057] The over-etching amount is determined based on the target gate angle, and the sidewall material layer 4 on the side of the gate 3 is over-etched based on the over-etching amount to obtain the target gate angle.
[0058] It should be noted that, due to the presence of sacrificial layer 5, the gate angle can be adjusted within a certain range by fine-tuning the over-etching amount during the sidewall over-etching process to better meet the final chip testing requirements. Furthermore, it should be noted that adjusting the over-etching amount only fine-tunes the gate angle; the gate angle is primarily inherited from the previous layer.
[0059] Based on the above embodiments, since a sacrificial layer is deposited before the sidewall material layer to protect the oxide layer under the base, the base can be better removed by appropriately increasing the over-etching amount during sidewall etching. At the same time, the presence of the sacrificial layer will not affect the oxide layer.
[0060] This application embodiment also provides a sidewall, including: a sidewall prepared by the sidewall etching method described above.
[0061] It should be noted that the sidewall in this embodiment only includes the sidewall material layer 4 covering the side of the gate 3, and does not have a base.
[0062] Based on the above embodiments, the sidewall of this application is prepared by the above sidewall etching method. Since a sacrificial layer is deposited before the sidewall material layer is deposited to protect the oxide layer under the base, the base can be better removed by appropriately increasing the over-etching amount during sidewall etching. At the same time, due to the presence of the sacrificial layer, it will not affect the oxide layer. Therefore, compared with the traditional sidewall, the obtained sidewall does not have a base and will not lose the oxide layer.
[0063] The following examples illustrate the sidewall etching process. Please refer to them. Figure 4 and Figure 5 , Figure 4 This is a schematic diagram of the structure before sidewall etching provided in an embodiment of this application; Figure 5This is a schematic diagram of the sidewall after etching, provided in an embodiment of this application. The specific process is as follows:
[0064] 1. A well region is formed in a substrate 1, including a P-well 11 and an N-well 12; an oxide layer 2 is formed on the surface of the substrate 1; a polysilicon layer, a silicon nitride layer, and a silicon oxide layer are sequentially formed along the thickness direction on the surface of the oxide layer 2 facing away from the substrate 1; after forming the polysilicon layer, silicon nitride layer, and silicon oxide layer, patterning is performed to form at least two gates 3; the gates 3 correspond one-to-one with the well regions;
[0065] 2. A sacrificial layer 5 (in this embodiment, the sacrificial layer 2 is an Al2O3 layer) is deposited on the surface of the substrate 1 by chemical vapor deposition, so that the sacrificial layer 5 covers the oxide layer 2 between adjacent gates 3 and the top surface of the gate 3;
[0066] 3. Deposit a sidewall material layer 4 (in this embodiment, a SiN layer) on the surface of the substrate with the sacrificial layer 5, resulting in the structure shown below. Figure 4 As shown; wherein, the sidewall material layer 4 covers the side of the gate 3 and the sacrificial layer 5 between adjacent gates 3, and also covers the sacrificial layer 5 on the top surface of the gate 3;
[0067] 4. Perform main etching on the sidewall material layer 4 to remove the sidewall material layer 4 on the top surface of the gate 3, and make the sidewall material layer 4 on the side of the gate 3 form a base.
[0068] 5. Determine the over-etching amount based on the height of the base plate, and then perform over-etching on the base plate according to the over-etching amount to remove the base plate. The resulting structure is as follows. Figure 5 As shown;
[0069] 6. After removing the base plate, the sacrificial layer 5 is removed by wet etching or dry etching to obtain the sidewall. The sidewall only covers the sidewall material layer 4 on the side of the gate 3 and does not have a base plate.
[0070] This document uses specific examples to illustrate the principles and implementation methods of this application. The various embodiments are progressive, with each embodiment focusing on its differences from others. Similar or identical parts between embodiments can be referred to interchangeably. The descriptions of the embodiments above are merely illustrative of the method and core ideas of this application. For those skilled in the art, various improvements and modifications can be made to this application without departing from its principles, and these improvements and modifications also fall within the scope of protection of the claims of this application.
[0071] It should also be noted that, in this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.
Claims
1. A sidewall etching method, characterized in that, include: An initial structure is formed on a substrate, the initial structure including an oxide layer formed on the surface of the substrate and at least two gates formed on the surface of the oxide layer; A sacrificial layer is deposited such that the sacrificial layer at least covers the oxide layer between adjacent gates; A sidewall material layer is deposited, the sidewall material layer at least covering the gate sidewall and the sacrificial layer between adjacent gates; The sidewall material layer is etched to remove the sidewall material layer on the top surface of the gate, and the sidewall material layer on the side surface of the gate forms a base. The over-etching amount is determined based on the height of the base, and the base is over-etched according to the over-etching amount to remove the base; After removing the base, the sacrificial layer is removed to obtain the sidewall.
2. The sidewall etching method according to claim 1, characterized in that, The deposition of the sacrificial layer, such that the sacrificial layer at least covers the oxide layer between adjacent gates, includes: The sacrificial layer is deposited by chemical vapor deposition, so that the sacrificial layer covers the oxide layer between adjacent gates and the top surface of the gate.
3. The sidewall etching method according to claim 2, characterized in that, The sacrificial layer is a metal oxide layer.
4. The sidewall etching method according to claim 1, characterized in that, The removal of the sacrificial layer includes: The sacrificial layer is removed by wet etching.
5. The sidewall etching method according to claim 4, characterized in that, The removal of the sacrificial layer by wet etching includes: The sacrificial layer is removed by wet etching using a wet etching solution comprising HCl, H2O2, and H2O.
6. The sidewall etching method according to claim 1, characterized in that, The removal of the sacrificial layer includes: The sacrificial layer is removed by dry etching.
7. The sidewall etching method according to claim 6, characterized in that, The removal of the sacrificial layer by dry etching includes: The sacrificial layer is removed by dry etching using reactive gases, including Cl2 and BCl3.
8. The sidewall etching method according to claim 1, characterized in that, The sidewall material layer is a SiN layer.
9. The sidewall etching method according to any one of claims 1 to 8, characterized in that, After removing the base plate and before removing the sacrificial layer, the procedure further includes: The over-etching amount is determined based on the target gate angle, and the sidewall material layer on the side of the gate is over-etched based on the over-etching amount to obtain the target gate angle.
10. A sidewall, characterized in that, include: The sidewall is prepared by the sidewall etching method according to any one of claims 1 to 9.