Method and apparatus for controlling thickness of injection protective layer

Abstract

The application discloses an injection protection layer thickness control method and device, which comprises the following steps: in the stage of etching the gate side wall, oxygen in the etching gas is ionized to oxidize the surface of a substrate, and a native oxide layer is formed on the surface of the substrate; and in the etching stage, the thickness of the native oxide layer is controlled by setting a bias power according to the thickness control specification requirements, so that the injection protection layer with the thickness meeting the thickness control specification is formed, the injection concentration and depth during the source-drain injection can meet the requirements, the electrical performance of a device is ensured, and the application range of the etching technology is expanded.

Description

Technical Field

[0001] This invention relates to the field of semiconductor integrated circuit technology, and in particular to a method and apparatus for controlling the thickness of an implantation protective layer. Background Technology

[0002] During the sidewall etching stage of the metal gate process, a native oxide layer naturally forms on the silicon substrate surface while the sidewalls are being formed. This native oxide layer is generally used as a protective layer during subsequent shallow doped source / drain implantation. Since the thickness of this native oxide layer has a certain influence on the implantation concentration and depth, its growth thickness needs to be monitored.

[0003] However, current technology has not made a clear study on the formation mechanism and control method of the above-mentioned primary oxide layer; at the same time, there is no specific research on how to control the thickness of the dielectric layer of the primary oxide layer during the sidewall etching process.

[0004] Therefore, it is necessary to provide a technique for growth control of the injected protective layer thickness to solve the above-mentioned problems in the prior art. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned defects in the prior art and to provide a method and apparatus for controlling the thickness of the injected protective layer.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] This invention provides a method for controlling the thickness of an injected protective layer, comprising:

[0008] Provides a semiconductor substrate on which gates are formed;

[0009] During the gate sidewall etching stage, oxygen in the etching gas is plasma-ionized to oxidize the substrate surface and form a native oxide layer on the substrate surface.

[0010] During the etching stage, the thickness of the primary oxide layer is controlled by setting a bias power according to the thickness control specifications, so as to form an injection protective layer that meets the thickness control specifications.

[0011] Furthermore, by adjusting the magnitude of the bias power during the setting, the depth of the formed oxygen plasma entering the substrate surface is adjusted, thereby adjusting the oxidation depth when oxidizing the substrate surface and achieving control over the thickness of the primary oxide layer.

[0012] Furthermore, by increasing the bias power, the depth of the oxygen plasma entering the substrate surface is increased, thereby increasing the thickness of the primary oxide layer; by decreasing the bias power, the depth of the oxygen plasma entering the substrate surface is decreased, thereby reducing the thickness of the primary oxide layer.

[0013] Furthermore, by detecting the thickness of the native oxide layer formed on the previous substrate and comparing it with the control specification, when the detection result is greater than the upper limit of the control specification, the bias power is reduced before the gate sidewall etching is performed on the next substrate; when the detection result is less than the lower limit of the control specification, the bias power is increased before the gate sidewall etching is performed on the next substrate, so that the thickness of the native oxide layer is kept within the control specification.

[0014] Furthermore, by utilizing the relationship between the bias voltage and the bias power, the magnitude of the bias power can be adjusted by regulating the level of the bias voltage.

[0015] Furthermore, it also includes: establishing a relationship model between the bias voltage and the thickness of the primary oxide layer, for automatic control of the thickness of the primary oxide layer.

[0016] The present invention also provides an injection protective layer thickness control device, comprising:

[0017] The detection module is used to detect the thickness of the native oxide layer formed on the substrate surface during the gate sidewall etching stage.

[0018] The adjustment module, located on the etching equipment, is used to set the bias power during the etching process;

[0019] The control module is used to control the thickness of the primary oxide layer by setting the bias power through the adjustment module during the etching stage, according to the thickness control specifications, so as to form an injection protective layer that meets the thickness control specifications.

[0020] Furthermore, the control module adjusts the bias power by controlling the adjustment module during the setting process, thereby regulating the depth of the oxygen plasma formed by ionizing oxygen in the etching gas into the substrate surface. This regulates the oxidation depth during substrate surface oxidation, thus controlling the thickness of the primary oxide layer. Specifically, increasing the bias power increases the depth of the oxygen plasma into the substrate surface, thereby increasing the thickness of the primary oxide layer; conversely, decreasing the bias power decreases the depth of the oxygen plasma into the substrate surface, thereby reducing the thickness of the primary oxide layer.

[0021] Furthermore, the control module compares the thickness detection result of the native oxide layer formed on the previous substrate with the control specification. When the detection result is greater than the upper limit of the control specification, the bias power is reduced before the gate sidewall etching is performed on the next substrate. When the detection result is less than the lower limit of the control specification, the bias power is increased before the gate sidewall etching is performed on the next substrate, so that the thickness of the native oxide layer is kept within the control specification.

[0022] Furthermore, the adjustment module adjusts the bias power by regulating the level of the bias voltage.

[0023] As can be seen from the above technical solution, this invention, by setting and adjusting the bias power during the gate sidewall etching stage, can regulate the depth of oxygen plasma entering the substrate surface during etching. This allows for adjustment of the oxidation depth of the substrate surface during oxygen plasma oxidation, thereby achieving effective control over the thickness of the native oxide layer. Specifically, the bias power can be increased by increasing the bias voltage to increase the depth of oxygen plasma entering the substrate surface, thus increasing the thickness of the native oxide layer; conversely, the bias power can be decreased by decreasing the bias voltage to decrease the depth of oxygen plasma entering the substrate surface, thus reducing the thickness of the native oxide layer. Thus, when the thickness of the native oxide layer formed on the previous substrate is detected to be greater than the upper limit or less than the lower limit of the control specification, the bias voltage can be adjusted accordingly before gate sidewall etching on the subsequent substrate, ensuring that the thickness of the native oxide layer formed on the subsequent substrate remains within the control specification. Furthermore, by establishing a relationship model between the bias voltage and the native oxide layer thickness, automatic control of the native oxide layer thickness can be achieved, ensuring that the implantation concentration and depth during subsequent ion implantation meet the requirements, thus guaranteeing the electrical performance of the device. Attached Figure Description

[0024] Figure 1 This is a flowchart of a preferred embodiment of the present invention for controlling the thickness of an injection protective layer;

[0025] Figure 2 This is a schematic diagram of the structure of an injection protective layer thickness control device according to a preferred embodiment of the present invention;

[0026] Figure 3 This is a schematic diagram illustrating the relationship between bias voltage and native oxide layer thickness according to a preferred embodiment of the present invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art. The terms "comprising" and similar expressions used herein mean that the element or object preceding the word covers the element or object listed after the word and its equivalents, but does not exclude other elements or objects.

[0028] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0029] Please see Figure 1 , Figure 1 This is a block diagram illustrating the principle of a method for controlling the thickness of an injection protective layer according to a preferred embodiment of the present invention. Figure 1 As shown, a method for controlling the thickness of an injection protective layer according to the present invention includes:

[0030] Provides a semiconductor substrate on which gates are formed;

[0031] During the gate sidewall etching stage, oxygen in the etching gas is plasmaized to oxidize the substrate surface and form a native oxide layer on the substrate surface.

[0032] During the etching stage, the thickness of the native oxide layer is controlled by setting the bias power according to the thickness control specifications, so as to form an injection protective layer that meets the thickness control specifications.

[0033] In some embodiments, the substrate may be a silicon substrate, a germanium substrate, or a silicon-on-insulator substrate, a germanium-on-insulator substrate, or other materials that can be oxidized. The following description uses a silicon substrate as an example.

[0034] In some embodiments, the gate may be a conventional polysilicon gate or a metal gate. The gate sidewall may be a conventional silicon nitride sidewall.

[0035] In some embodiments, the process gas used for gate sidewall etching may be an etching gas from a conventional sidewall etching process menu; such conventional etching gases contain oxygen.

[0036] In some embodiments, a silicon wafer substrate may be used, and a gate, such as a metal gate, may be formed on the silicon substrate using conventional CMOS processes.

[0037] Next, a sidewall material layer, such as a silicon nitride sidewall material layer, can be grown on the surface of the silicon substrate using a conventional deposition process.

[0038] Then, a conventional sidewall process can be used to form a sidewall structure on both sides of the gate.

[0039] During gate sidewall etching, since the etching gas contains oxygen, the oxygen in the etching gas can be plasmaized to oxidize the silicon substrate surface while etching the silicon nitride sidewall material, thereby forming a native oxide layer of silicon oxide on the silicon substrate surface.

[0040] The aforementioned native silicon oxide layer can be used as a protective layer during subsequent source / drain implantation of the silicon substrate, thus saving the step of depositing a dielectric layer as an implantation protective layer. Since the thickness of this native silicon oxide layer has a certain influence on the implantation concentration and depth, its growth thickness needs to be monitored. Furthermore, the thickness of the native silicon oxide layer can be controlled by adjusting the bias power during etching to form a silicon oxide implantation protective layer that meets thickness control specifications, ensuring that the subsequent ion implantation concentration and depth meet the requirements and guaranteeing the device's electrical performance.

[0041] Since silicon substrates are oxidized starting from the surface, and to form an oxide layer on the silicon substrate surface, the silicon substrate surface needs to be in full contact with oxygen. Therefore, the depth to which the oxygen plasma formed during etching can penetrate the silicon substrate directly determines the formation depth of the primary silicon oxide layer. Furthermore, since the intensity of the oxygen plasma is directly proportional to the depth to which it can penetrate the silicon substrate, and the intensity of the oxygen plasma can be adjusted by changing the bias power, the depth to which the oxygen plasma formed during etching penetrates the silicon substrate surface can be adjusted before each etching operation. This allows for control over the oxidation depth of the silicon substrate surface and the thickness of the primary silicon oxide layer.

[0042] In some embodiments, by increasing the bias power, the depth of oxygen plasma penetrating the silicon substrate surface can be increased, thereby increasing the thickness of the native silicon oxide layer. Conversely, by decreasing the bias power, the depth of oxygen plasma penetrating the silicon substrate surface can be decreased, thereby reducing the thickness of the native silicon oxide layer.

[0043] In some embodiments, the thickness of the original silicon oxide layer formed after etching can be detected to monitor whether the thickness of the original silicon oxide layer meets the control specifications.

[0044] After obtaining the thickness data of the native silicon oxide layer on the current silicon substrate, the thickness detection results can be compared with the control specifications, and based on the comparison results, it can be determined whether the thickness of the native silicon oxide layer on the subsequent silicon substrate needs to be adjusted.

[0045] In some embodiments, when the thickness of the native silicon oxide layer on the preceding silicon substrate (or multiple preceding silicon substrates) exceeds the upper limit of the control specification, the bias power can be reduced before gate sidewall etching of the subsequent silicon substrate. This reduces the intensity of the oxygen plasma, decreasing the depth of the oxygen plasma penetrating the surface of the subsequent silicon substrate, thus correspondingly reducing the thickness of the native silicon oxide layer. Consequently, the thickness of the native silicon oxide layer detected on the subsequent silicon substrate is less than the upper limit of the control specification and falls within the control specification. Conversely, when the thickness of the native silicon oxide layer on the preceding silicon substrate (or multiple preceding silicon substrates) is less than the lower limit of the control specification, the bias power can be increased before gate sidewall etching of the subsequent silicon substrate. This increases the intensity of the oxygen plasma, increasing the depth of the oxygen plasma penetrating the surface of the subsequent silicon substrate, thus correspondingly increasing the thickness of the native silicon oxide layer. Consequently, the thickness of the native silicon oxide layer detected on the subsequent silicon substrate is greater than the lower limit of the control specification and falls within the control specification.

[0046] If the detected thickness of the native silicon oxide layer is within the normal range of the control specifications, there is no need to adjust the existing bias power.

[0047] Furthermore, by utilizing the positive correlation between bias voltage and bias power, the bias voltage can be adjusted by modifying parameters in the etching process menu during setup, thereby adjusting the magnitude of the bias power.

[0048] In a preferred embodiment, a model relating bias voltage to native oxide layer thickness can be established for automatic control of the native oxide layer thickness. This can be achieved by collecting native oxide layer thickness detection data corresponding to a specific bias voltage over a long period and analyzing the relative error of the detected native oxide layer thickness under different bias voltages, thus establishing a database. In this way, a model relating native oxide layer thickness to bias voltage can be established through mathematical calculations and fitting. This allows for the simple and quick acquisition of the corresponding bias voltage through data processing and database queries, based on different injection concentrations and depth requirements for source / drain implantation, and its setting on the sidewall etching process menu, eliminating the need for experimental acquisition of the corresponding bias voltage.

[0049] Subsequently, it is only necessary to continuously monitor the thickness of the native oxide layer and use process control technology to ensure that the actual thickness of the native oxide layer obtained on each silicon substrate under controlled conditions falls within the control specifications and meets the CPK requirements under the ±3σ control limit.

[0050] The following detailed description of an injection protective layer thickness control device according to the present invention, with reference to specific embodiments and accompanying drawings, will provide a detailed explanation.

[0051] Please see Figure 2 The present invention provides an injection protective layer thickness control device, which can be used to implement the injection protective layer thickness control method of the present invention described above. The injection protective layer thickness control device includes several main components such as a detection module, an adjustment module, and a control module.

[0052] An etching apparatus for etching the gate sidewalls can be used, and an adjustment module can be mounted on the etching apparatus. The detection module, adjustment module, and control module can establish communication with the etching apparatus.

[0053] The detection module is used to detect the thickness of the native oxide layer formed on the substrate surface during the gate sidewall etching stage.

[0054] Since the thickness of the native oxide layer is relatively thin, typically around 10 angstroms, and since the native oxide layer that actually needs to be controlled is located in the small source / drain injection regions on both sides of the gate, the thickness of the native oxide layer at the source / drain injection region can be indirectly characterized by detecting the thickness of the silicon oxide layer on the test PAD on the substrate, which is dedicated to detecting the film thickness, and a corresponding control specification can be established.

[0055] In a preferred embodiment, the control specification can be set, for example, to 26.9 ± 3 angstroms. That is, if the thickness data obtained from measuring the silicon oxide layer thickness on the test PAD falls within the control specification of 26.9 ± 3 angstroms, it indicates that the native silicon oxide layer thickness at the source / drain implantation region is within approximately 10 angstroms, which meets the implantation process requirements. The effectiveness of this control specification can be verified through offline testing.

[0056] The adjustment module is used to set and adjust the bias power during the etching process.

[0057] In a preferred embodiment, the positive correlation between bias voltage and bias power can be utilized to adjust the bias voltage and thus adjust the bias power. For example, an RF bias power supply on an etching device can be used, and the adjustment module can be connected to the RF bias power supply to control the bias voltage, i.e., the bias power.

[0058] The radio frequency (RF) bias power supply can convert the gas introduced into the etching reaction chamber into plasma, which is used to etch films on silicon substrates, such as silicon nitride sidewall material films. In this way, the oxygen in the etching gas also forms oxygen plasma under the action of the RF bias power supply, which can participate in the etching of silicon nitride sidewall material films on silicon substrates while simultaneously oxidizing the surface of the silicon substrate.

[0059] In a preferred embodiment, the adjustment module may be an actuator module disposed on an etching device that controls the adjustment of the bias voltage generated by the RF bias power supply.

[0060] The control module is used during the etching stage to control the thickness of the native oxide layer by adjusting the bias voltage (i.e., setting the bias power) according to the thickness control specifications, so as to form an injection protective layer that meets the thickness control specifications.

[0061] In a preferred embodiment, the control module can adjust the bias voltage by controlling the adjustment module at the set time to adjust the bias power, thereby adjusting the intensity of the formed oxygen plasma and thus adjusting the depth of the oxygen plasma entering the substrate surface, thereby adjusting the oxidation depth when oxidizing the substrate surface and controlling the thickness of the primary oxide layer.

[0062] Specifically, by controlling the bias voltage to increase the bias power, the depth of oxygen plasma penetration into the substrate surface can be increased, thereby increasing the thickness of the primary oxide layer. Conversely, by controlling the bias voltage to decrease the bias power, the depth of oxygen plasma penetration into the substrate surface can be decreased, thereby reducing the thickness of the primary oxide layer.

[0063] Furthermore, the control module can compare the current native oxide layer thickness on the silicon substrate detected by the detection module with the control specifications, and decide whether to adjust the thickness of the native silicon oxide layer on the silicon substrate in the future based on the comparison results.

[0064] For example, when the thickness of the native silicon oxide layer on the previous silicon substrate (or multiple silicon substrates) exceeds the upper limit of the control specification, the bias voltage can be lowered by the control adjustment module before the gate sidewall etching of the subsequent silicon substrate. This reduces the bias power and decreases the intensity of the oxygen plasma, thereby reducing the depth of the oxygen plasma entering the surface of the subsequent silicon substrate. This results in a corresponding reduction in the thickness of the native silicon oxide layer, ensuring that the thickness of the native silicon oxide layer detected on the subsequent silicon substrate is less than the upper limit of the control specification and falls within the control specification. Conversely, if the thickness of the native silicon oxide layer on the current silicon substrate (or the preceding silicon substrates) is less than the lower limit of the control specification, the bias voltage can be increased by the control adjustment module before the gate sidewall etching of the subsequent silicon substrate. This increases the bias power and the intensity of the oxygen plasma, thereby increasing the depth of the oxygen plasma into the surface of the subsequent silicon substrate. This results in a corresponding increase in the thickness of the native silicon oxide layer, ensuring that the thickness of the native silicon oxide layer detected on the subsequent silicon substrate is greater than the lower limit of the control specification and falls within the control specification.

[0065] If the test results fall within the control specifications and are under control, there is no need to adjust the existing bias power.

[0066] Please see Figure 3 Through wafer fabrication experiments involving silicon nitride sidewall etching on patterned wafers with gates, and controlling variables solely by adjusting the bias voltage, the relationship between the thickness of the native silicon oxide layer and the bias voltage was observed. The results showed that as the bias voltage (bias power) decreased, the thickness of the native oxide layer also gradually decreased. Therefore, by adjusting the bias power of the sidewall etching step, the thickness of the native oxide layer was successfully controlled. Furthermore, the obtained native oxide layer exhibited a uniform thickness distribution across the entire wafer surface. Simultaneously, the key dimensions and morphology of the final silicon nitride sidewalls remained largely unchanged, demonstrating the practical feasibility of this invention.

[0067] In a preferred embodiment, the control module may include a host computer. The host computer is connected to the production execution system of the etching equipment and can control the radio frequency bias power supply of the etching equipment through the production execution system to ensure that the bias voltage generated meets the control requirements.

[0068] In a preferred embodiment, an editor can be established on the host computer. By collecting primary oxide layer thickness detection data corresponding to a certain bias voltage over a long period, the relative error of the detected primary oxide layer thickness under different bias voltages can be analyzed, and a database can be established. Thus, through mathematical calculations and fitting, a correspondence model between primary oxide layer thickness and bias voltage can be established. This allows for the simple and quick acquisition of the corresponding bias voltage through data processing and database queries, based on different injection concentrations and depth requirements for source / drain implantation, and its setting on the sidewall etching process menu, eliminating the need to obtain the corresponding bias voltage experimentally.

[0069] In a preferred embodiment, a process control module can be established on the host computer. Subsequently, it is only necessary to continuously monitor the thickness of the native oxide layer online, and process control technology can be used to ensure that the actual thickness of the native oxide layer falls within the control specifications and meets the CPK requirements under the ±3σ control limit.

[0070] In a preferred embodiment, a control module operation menu (sidewall etching process menu) can be set on the graphical user interface of the etching equipment. This allows for the monitoring of the bias voltage setting based on the native oxide layer thickness detection results displayed on the graphical user interface, and the bias voltage setting value on the sidewall etching process menu can be modified on-site via the graphical user interface. Therefore, two-level control of the sidewall etching step, both on-site and remote, can be achieved.

[0071] In summary, this invention, by adjusting the bias power during the gate sidewall etching stage, can regulate the depth of oxygen plasma entering the substrate surface during etching. This allows for control over the oxidation depth of the substrate surface during oxygen plasma oxidation, thereby achieving effective control over the thickness of the native oxide layer. Specifically, increasing the bias voltage increases the bias power, thus increasing the depth of oxygen plasma penetration and increasing the native oxide layer thickness; conversely, decreasing the bias voltage decreases the bias power, thus decreasing the thickness of the native oxide layer. Therefore, when the thickness of the native oxide layer formed on the previous substrate is detected to be greater than the upper limit or less than the lower limit of the control specification, the bias voltage can be adjusted accordingly before gate sidewall etching on the subsequent substrate to keep the thickness of the native oxide layer formed on the subsequent substrate within the control specification. Furthermore, by establishing a model relating the bias voltage and the native oxide layer thickness, automatic control of the native oxide layer thickness can be achieved, ensuring that the implantation concentration and depth during subsequent ion implantation meet requirements and guaranteeing the device's electrical performance.

[0072] Meanwhile, this invention expands the application scope of etching technology by using etching technology to grow a dielectric layer with adjustable thickness on the surface of a wafer substrate.

[0073] While embodiments of the present invention have been described in detail above, it will be apparent to those skilled in the art that various modifications and variations can be made to these embodiments. However, it should be understood that such modifications and variations fall within the scope and spirit of the invention as set forth in the claims. Furthermore, the invention described herein may have other embodiments and can be implemented or carried out in various ways.

Claims

1. A method for controlling the thickness of an injection protective layer, characterized in that, include: Provides a semiconductor substrate on which gates are formed; During the gate sidewall etching stage, oxygen in the etching gas is plasma-ionized to oxidize the substrate surface and form a native oxide layer on the substrate surface. In the etching stage, the thickness of the primary oxide layer is controlled by setting a bias power according to the thickness control specifications, so as to form an implantation protective layer that meets the thickness control specifications. The bias power is used to adjust the intensity of the oxygen plasma formed in the oxygen plasma ionization. By adjusting the magnitude of the bias power during the setting, the depth of the formed oxygen plasma entering the substrate surface can be adjusted to regulate the oxidation depth when oxidizing the substrate surface, thereby controlling the thickness of the primary oxide layer. By detecting the thickness of the native oxide layer formed on the previous substrate and comparing it with the control specification, if the detection result is greater than the upper limit of the control specification, the bias power is reduced before the gate sidewall etching is performed on the next substrate. If the detection result is less than the lower limit of the control specification, the bias power is increased before the gate sidewall etching is performed on the next substrate, so that the thickness of the native oxide layer is kept within the control specification.

2. The method for controlling the thickness of the injected protective layer according to claim 1, characterized in that, The thickness of the primary oxide layer is increased by increasing the bias power to increase the depth of the oxygen plasma entering the substrate surface; the thickness of the primary oxide layer is reduced by decreasing the bias power to decrease the depth of the oxygen plasma entering the substrate surface.

3. The method for controlling the thickness of the injected protective layer according to claim 1, characterized in that, By utilizing the relationship between bias voltage and bias power, the magnitude of bias power can be adjusted by regulating the level of the bias voltage.

4. The method for controlling the thickness of the injected protective layer according to claim 3, characterized in that, Also includes: A model is established to establish the relationship between the bias voltage and the thickness of the primary oxide layer, which is used to automatically control the thickness of the primary oxide layer.

5. A device for controlling the thickness of an injection protective layer, characterized in that, include: The detection module is used to detect the thickness of the native oxide layer formed on the substrate surface during the gate sidewall etching stage. An adjustment module, located on the etching equipment, is used to set the bias power, which is used to adjust the intensity of the oxygen plasma formed by ionizing oxygen in the etching gas. The control module is used to control the thickness of the primary oxide layer by setting the bias power through the adjustment module during the etching stage, according to the thickness control specifications, so as to form an injection protection layer that meets the thickness control specifications. The control module adjusts the bias power by controlling the adjustment module at the set time, thereby adjusting the depth of the oxygen plasma formed by ionizing the oxygen in the etching gas into the substrate surface, so as to adjust the oxidation depth when oxidizing the substrate surface and achieve control of the thickness of the primary oxide layer. The control module compares the thickness detection result of the native oxide layer formed on the previous substrate with the control specification. When the detection result is greater than the upper limit of the control specification, the bias power is reduced before the gate sidewall etching is performed on the next substrate. When the detection result is less than the lower limit of the control specification, the bias power is increased before the gate sidewall etching is performed on the next substrate, so that the thickness of the native oxide layer is kept within the control specification.

6. The injection protective layer thickness control device according to claim 5, characterized in that, in, The thickness of the primary oxide layer is increased by increasing the bias power to increase the depth of the oxygen plasma entering the substrate surface; the thickness of the primary oxide layer is reduced by decreasing the bias power to decrease the depth of the oxygen plasma entering the substrate surface.

7. The injection protective layer thickness control device according to claim 5, characterized in that, The adjustment module adjusts the bias power by regulating the level of the bias voltage.

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