Semiconductor device fabrication methods

Abstract

This disclosure provides a method for fabricating a semiconductor device, comprising: providing a semiconductor substrate, wherein a native oxide layer is formed on the surface of the semiconductor substrate; doping the native oxide layer with fluorine ions; and oxidizing the semiconductor substrate located at the bottom of the native oxide layer to form an oxide layer, wherein the gas used in the oxidation process reacts with the native oxide layer to convert the native oxide layer into gaseous byproducts, thereby removing the native oxide layer. This disclosure can effectively remove the native oxide layer and form a high-quality oxide layer, avoiding the impact of residual native oxide layer on the performance of the oxide layer, thereby improving the performance of the semiconductor device.

Description

Technical Field

[0001] This disclosure relates to the field of semiconductor manufacturing technology, and in particular to a method for preparing a semiconductor device. Background Technology

[0002] With the continuous development of semiconductor technology, the size of semiconductor devices is gradually shrinking, which also places higher demands on the performance of semiconductor devices.

[0003] Semiconductor substrates are prone to oxidation in water and oxygen environments to form native oxide layers. Native oxide layers usually have defects such as lattice defects and uneven thickness. Therefore, it is usually necessary to remove the native oxide layer and reform a high-quality oxide layer.

[0004] However, the original oxide layer is currently difficult to completely remove, resulting in the need to improve the quality of the formed oxide layer, which in turn affects the performance of semiconductor devices. Summary of the Invention

[0005] This disclosure provides a method for fabricating a semiconductor device, which at least improves the ability to remove the native oxide layer or even completely removes the native oxide layer, thereby obtaining a high-quality oxide layer to improve the performance and reliability of the semiconductor device.

[0006] According to some embodiments of this disclosure, one aspect of this disclosure provides a method for fabricating a semiconductor device, comprising: providing a semiconductor substrate, wherein a native oxide layer is formed on the surface of the semiconductor substrate; doping the native oxide layer with fluorine ions; oxidizing the semiconductor substrate located at the bottom of the native oxide layer to form an oxide layer, wherein the gas used in the oxidation process reacts with the native oxide layer to convert the native oxide layer into gaseous byproducts to remove the native oxide layer.

[0007] In some embodiments, the method for fluorine ion doping includes: providing a fluorine-containing gas; subjecting the fluorine-containing gas to decoupled plasma treatment to form a fluorine plasma; and injecting the fluorine plasma into the native oxide layer.

[0008] In some embodiments, the fluorine-containing gas includes fluorine-containing compounds that are gaseous at room temperature.

[0009] In some embodiments, the fluorinated compound includes XeF2.

[0010] In some embodiments, the process parameters used for fluorine ion doping include: a power supply of 1500W to 2200W, a power supply duty cycle of 10% to 50%, and a chamber pressure of 10mt to 50mt.

[0011] In some embodiments, the method for fluorine ion doping includes: forming a fluorine-doped layer on the surface of the native oxide layer; performing an annealing treatment to allow fluorine ions in the fluorine-doped layer to diffuse into the native oxide layer; and removing the fluorine-doped layer.

[0012] In some embodiments, the annealing process includes microwave annealing, flash annealing, or laser annealing.

[0013] In some embodiments, the oxidation process uses gases including hydrogen and oxygen.

[0014] In some embodiments, the primary oxide layer is made of silicon oxide; hydrofluoric acid is formed during the oxidation process, and the hydrofluoric acid reacts with the primary oxide layer to convert the primary oxide layer into gaseous fluorosilicone compounds and water vapor.

[0015] In some embodiments, the oxidation treatment employs an in-situ water vapor generation oxidation method.

[0016] In some embodiments, the oxidation process includes a first oxidation step and a second oxidation step performed sequentially, wherein the flow rate of hydrogen in the first oxidation step is greater than the flow rate of hydrogen in the second oxidation step, and the process temperature used in the first oxidation step is lower than the process temperature used in the second oxidation step.

[0017] In some embodiments, the hydrogen flow rate in the first oxidation step is 1.005 to 1.05 times the hydrogen flow rate in the second oxidation step.

[0018] In some embodiments, the flow rate of hydrogen in the second oxidation step is 0.1 slm to 2 slm.

[0019] In some embodiments, the oxygen flow rate during the oxidation process is 10 slm to 30 slm.

[0020] In some embodiments, the process temperature used in the first oxidation step is 400°C to 600°C; the process temperature used in the second oxidation step is 900°C to 1100°C.

[0021] In some embodiments, the chamber pressure during the oxidation treatment is 8 to 20 torr.

[0022] In some embodiments, prior to the fluorine ion doping, the process further includes pre-cleaning the native oxide layer to reduce its thickness.

[0023] In some embodiments, the oxide layer is a gate oxide layer.

[0024] The technical solutions provided in this disclosure have at least the following advantages:

[0025] Before oxidizing the semiconductor substrate, the native oxide layer is first doped with fluorine ions. During the oxidation process, the fluorine-doped native oxide layer reacts with the gas used in the oxidation process, converting the native oxide layer into gaseous byproducts, thereby achieving the purpose of removing the native oxide layer. In other words, in the embodiments of this disclosure, the native oxide layer can be removed simultaneously during the oxide layer formation process using oxidation, avoiding the adverse effects of residual native oxide layer on the oxide layer, thus obtaining a high-quality oxide layer and improving the performance of the semiconductor device. Attached Figure Description

[0026] One or more embodiments are illustrated by way of example with corresponding pictures in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Unless otherwise stated, the pictures in the accompanying drawings do not constitute a limitation on scale. In order to more clearly illustrate the technical solutions in the embodiments of this disclosure or the conventional technology, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figures 1 to 3 This is a schematic diagram of the structure corresponding to each step of a semiconductor device fabrication method;

[0028] Figures 4 to 9 This is a schematic diagram of the structure corresponding to each step of a method for fabricating a semiconductor device according to an embodiment of this disclosure. Detailed Implementation

[0029] As can be seen from the background technology, there is currently a problem that the quality of the oxide layer needs to be improved.

[0030] Figures 1 to 3 This is a schematic diagram showing the structural steps corresponding to each step of a semiconductor device fabrication method. (Reference) Figure 1 A semiconductor substrate 100 is provided, the surface of which has a native oxide layer 101; Reference Figure 2 Remove the original oxide layer 101; Reference Figure 3An oxide layer 102 is formed on the surface of a semiconductor substrate 100. Using this fabrication method, a portion of the original oxide layer 101 remains on the surface of the formed oxide layer 102. This original oxide layer 101 is retained within the semiconductor device, leading to overall quality deviations in the oxide layer 102 and affecting the electrical performance of the semiconductor device. For example, when the oxide layer 102 serves as the gate oxide layer of the semiconductor device, the gate oxide layer plays a crucial role in controlling the gate switch. The presence of the residual original oxide layer 101 weakens the gate oxide layer's ability to control the gate switch, resulting in reduced reliability and electrical performance of the semiconductor device.

[0031] Analysis revealed that the pre-cleaning process 11 removes the native oxide layer 101; for example, the pre-cleaning process 11 can be a wet cleaning process. However, even after the pre-cleaning process 11, the native oxide layer 101 is still difficult to completely remove. For example, after the pre-cleaning process 11, the surface of the semiconductor substrate 100 may still have a native oxide layer 101 of more than 6 angstroms remaining. If the semiconductor substrate 100 is oxidized on this basis to form an oxide layer 102, the remaining native oxide layer 101 will still be located on the surface of the oxide layer 102.

[0032] This disclosure provides a method for fabricating a semiconductor device, which involves doping a native oxide layer with fluorine ions; oxidizing a semiconductor substrate located at the bottom of the native oxide layer to form an oxide layer; and using a gas in the oxidation process to react with the native oxide layer, converting the native oxide layer into a gaseous byproduct. In this way, the native oxide layer can be removed as much as possible to improve the quality of the formed oxide layer.

[0033] The embodiments of this disclosure will now be described in detail with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been provided in the embodiments of this disclosure to facilitate a better understanding of the disclosure. However, the technical solutions claimed in this disclosure can be implemented even without these technical details and various variations and modifications based on the following embodiments.

[0034] Figures 4 to 9 The following is a schematic diagram of the structure corresponding to each step of a method for fabricating a semiconductor device according to an embodiment of this disclosure:

[0035] refer to Figure 4 A semiconductor substrate 201 is provided, and a native oxide layer 202 is formed on the surface of the semiconductor substrate 201.

[0036] The semiconductor substrate 201 can be made of silicon, germanium, silicon-germanium, or silicon carbide; it can also be silicon-on-insulator (SOI) or germanium-on-insulator (GOI). The semiconductor substrate 201 is easily oxidized in an environment containing water and oxygen to form a native oxide layer 202. The native oxide layer 202 is made of a native oxide. Typically, the quality of the native oxide layer 202 is relatively poor, exhibiting characteristics such as poor density, poor thickness uniformity, or numerous lattice defects.

[0037] In some embodiments, the semiconductor substrate 201 may be a silicon substrate, and correspondingly, the primary oxide layer 202 may be made of silicon oxide. In other embodiments, the semiconductor substrate 201 may be a germanium substrate, and correspondingly, the primary oxide layer 202 may be made of germanium oxide. It is also understood that when the semiconductor substrate 201 is made of germanium-silicon, the primary oxide layer 202 may be made of a germanium-silicon oxide.

[0038] A portion of the surface of the semiconductor substrate 201 may also have a mask layer 203. The mask layer 203 has an opening directly opposite the portion of the surface of the semiconductor substrate 201, and the native oxide layer 202 is located within the opening. The mask layer 203 can protect the portion of the surface of the semiconductor substrate 201, preventing subsequent oxidation treatment of the semiconductor substrate 201 directly beneath the mask layer 203. The material of the mask layer 203 can be silicon nitride or silicon oxynitride. It is understood that in some embodiments, the mask layer 203 may not be formed on the surface of the semiconductor substrate 201, and correspondingly, the native oxide layer 202 may be located on the entire surface of the semiconductor substrate 201.

[0039] Subsequent process steps include doping the native oxide layer 202 with fluorine ions. In some embodiments, prior to fluorine ion doping, a pre-cleaning treatment of the native oxide layer may be performed to reduce its thickness.

[0040] refer to Figure 5 The original oxide layer 202 is pre-cleaned 21 to reduce its thickness.

[0041] By performing a pre-cleaning treatment 21 on the native oxide layer 202, the thickness of the native oxide layer 202 before subsequent fluorine ion doping is made relatively thin. On the one hand, a thinner native oxide layer 202 helps reduce the difficulty of the subsequent fluorine ion doping process, allowing for a shallower fluorine ion implantation depth. On the other hand, the pre-cleaning treatment 21 removes most of the thickness of the native oxide layer 202, making the thickness of the native oxide layer 202 that needs to be removed in the subsequent oxidation process relatively thin, thus making it easier to completely remove the native oxide layer in the subsequent oxidation process.

[0042] In some embodiments, after the pre-cleaning process 21, the thickness of the native oxide layer 202 is 6 to 10 angstroms, for example, the thickness of the native oxide layer 202 can be 7 angstroms, 8 angstroms, or 9 angstroms. Within this thickness range, the thickness of the native oxide layer 202 is not too thin, which helps to prevent fluoride ions from completely penetrating the native oxide layer 202 and entering the semiconductor substrate 201 in the subsequent fluoride ion doping step, thereby avoiding unnecessary doping of the semiconductor substrate 201; in addition, the thickness of the native oxide layer 202 is not too thick, which helps to reduce the difficulty and time required to remove the native oxide layer 202 in the subsequent oxidation process, thereby helping to further improve the degree of removal of the native oxide layer 202.

[0043] A wet cleaning process is used for pre-cleaning treatment 21. In one example, pre-cleaning treatment 21 can be performed using the RCA cleaning method, which is a wet chemical cleaning method. The RCA cleaning method includes four steps: The first step uses SPM reagent, which consists of H2SO4 and H2O2. SPM reagent can remove organic matter and metals from the surface of the original oxide layer 202; The second step uses DHF reagent, which consists of HF and H2O. DHF reagent can remove part of the original oxide layer 202 and inhibit the reformation of the original oxide layer 202; The third step uses APM reagent, which consists of NH4OH, H2O2, and H2O. APM reagent can remove particles attached to the original oxide layer 202; The fourth step uses HPM reagent, which consists of HCl, H2O2, and H2O. HPM reagent can remove sodium, iron, magnesium, and other metal contaminants attached to the original oxide layer 202.

[0044] It is understood that in some other embodiments, the pre-cleaning treatment 21 of the native oxide layer 202 may be omitted, and fluorine ion doping may be performed directly.

[0045] refer to Figure 6 Fluorine ion doping 22 was performed on the native oxide layer 202.

[0046] Fluorine ion doping 22 is performed on the native oxide layer 202 so that fluorine ions are present in the native oxide layer 202 during subsequent oxidation processes. These fluorine ions provide the basis for the chemical reactions required to remove the native oxide layer 202.

[0047] In some embodiments, the method of fluorine ion doping 22 includes: providing a fluorine-containing gas; performing decoupled plasma treatment on the fluorine-containing gas to form a fluorine plasma; and injecting the fluorine plasma into the native oxide layer 202.

[0048] Specifically, the provided fluorine-containing gas is used as the reaction gas, and a method similar to DPN (Decoupled Plasma Nitridation) is used to treat the fluorine-containing gas with decoupled plasma. Before fluorine ion doping 22, the semiconductor substrate 201 is placed in the plasma chamber, and then fluorine plasma is generated through inductive coupling. The fluorine plasma is then injected into the native oxide layer 202 in an ultra-shallow manner. In this way, when fluorine ions are doped into the native oxide layer 202, the fluorine plasma generated by inductive coupling does not easily penetrate into the semiconductor substrate 201, so the structure of the semiconductor substrate 201 is not damaged.

[0049] The fluorine-containing gas includes fluorine-containing compounds that are gaseous at room temperature. The products of the fluorine-containing compounds after decomposition will not affect the subsequent growth of the oxide layer. The products of decoupling plasma treatment of the fluorine-containing compounds are fluoride ions and ions of other elements contained in the corresponding fluorine-containing compounds.

[0050] refer to Figure 7 In some embodiments, the fluorine-containing compound used for fluorine ion doping 22 can be XeF2, and correspondingly, the products of decoupling plasma treatment of XeF2 are fluorine ions and xenon ions. The specific reaction formula is as follows:

[0051] XeF2→Xe + +2F - +e - (1)

[0052] In some embodiments, the process parameters for fluorine ion doping 22 may include: a power supply of 1500W to 2200W (e.g., 1500W, 1800W, or 2000W), a duty cycle of 10% to 50% (e.g., 10%, 30%, or 50%), and a chamber pressure of 10mt to 50mt (m torr, millitor, 1 torr = the pressure of 1 mm mercury column) (e.g., 10mt, 30mt, or 50mt). The concentration of fluorine ions implanted into the native oxide layer 202 is related to the power supply and duty cycle. Setting the power supply in this way allows for faster fluorine ion implantation, while the selection of the duty cycle parameter enables better ultra-shallow implantation of fluorine ions into the native oxide layer 202, avoiding fluorine ion implantation into the semiconductor substrate 201.

[0053] It is understood that the ions of other elements contained in the fluorine-containing compound generated in the fluorine ion doping step 22 will be carried out of the chamber by the carrier gas. In some embodiments, the fluorine-containing compound used for fluorine ion doping step 22 is XeF2, and correspondingly, the xenon ions generated in fluorine ion doping step 22 will be carried out of the chamber by the carrier gas.

[0054] In other embodiments, the method for fluorine ion doping 22 may also include: forming a fluorine-doped layer on the surface of the native oxide layer 202; performing an annealing treatment to allow fluorine ions in the fluorine-doped layer to diffuse into the native oxide layer 202; and removing the fluorine-doped layer. The material of the fluorine-doped layer can be fluorine-containing silicon nitride or fluorine-containing silicon oxynitride. The annealing treatment may include microwave annealing, flash annealing, or laser annealing. The heat energy and thermal oxidation provided by the annealing treatment can achieve ultra-shallow implantation of fluorine ions into the native oxide layer 202, and the fluorine-doped layer can be removed together with the native oxide layer 202 in subsequent oxidation processes.

[0055] refer to Figure 8 and Figure 9 The semiconductor substrate 201 located at the bottom of the native oxide layer 202 is subjected to oxidation treatment 23 to form an oxide layer 203. The gas used in the oxidation treatment reacts with the native oxide layer 202 to convert the native oxide layer 202 into gaseous byproducts, thereby removing the native oxide layer 202.

[0056] In some embodiments, the gases used in the oxidation process 23 include hydrogen and oxygen, hydrofluoric acid is formed in the oxidation process 23, and the hydrofluoric acid reacts with the native oxide layer 202 to convert the native oxide layer 202 into gaseous fluorosilicon compounds and water vapor.

[0057] Specifically, in oxidation treatment 23, hydrogen and oxygen react in the chamber to generate hydroxide ions. The hydroxide ions react with hydrogen ions to generate hydrogen ions and water vapor. The hydrogen ions react with the fluoride ions generated in the fluoride doping step 22 to generate hydrofluoric acid. After the original oxide layer 202 reacts with hydrofluoric acid, it is converted into gaseous fluoride and water vapor, thereby removing the original oxide layer 202.

[0058] In some embodiments, the primary oxide layer 202 is made of silicon oxide, and the corresponding byproducts of the oxidation treatment 23 are gaseous silicon fluoride and water vapor. In other embodiments, the primary oxide layer 202 is made of germanium oxide, and the corresponding byproduct of the oxidation treatment 23 is gaseous germanium fluoride. It can also be understood that when the primary oxide layer 202 is an oxide of germanium silicon, the corresponding byproducts of the oxidation treatment 23 are gaseous germanium silicon fluoride and water vapor. Taking silicon oxide as an example, the products of the reaction between the primary oxide layer 202 and hydrofluoric acid are silicon fluoride and water vapor, as shown in the following reaction formula:

[0059] H₂ + O₂ → 2OH⁻ - (2)

[0060] 2OH - +H2→H2O+H + (3)

[0061] H + +F - →HF (4)

[0062] SiO2O + HF → SiF4↑ + H2O↑ (5)

[0063] In some embodiments, the oxidation treatment 23 employs an in-situ steam generation oxidation method (ISSG), a novel low-pressure rapid oxidation thermal annealing process that can heat and cool the semiconductor substrate 201 in a short time, with low thermal budget and good temperature uniformity. ISSG generates a combustion-like chemical reaction on the surface of the semiconductor substrate 201 under high-temperature conditions in an atmosphere of hydrogen and oxygen. This reaction generates a large number of gaseous active free radicals, which participate in the oxidation process of the semiconductor substrate 201. Through the strong oxidizing effect of oxygen, the oxide layer 204 formed by ISSG has fewer crystal defects, lower interface state density, better thickness uniformity, and higher quality. Furthermore, since ISSG obtains the oxide layer 204 by oxidizing and thermally annealing the semiconductor substrate 201, meaning the raw material for growing the oxide layer 204 comes from the semiconductor substrate 201, the obtained oxide layer 204 is also embedded in a portion of the bottom of the semiconductor substrate 201.

[0064] It is understood that in some embodiments, the semiconductor substrate 201 is a silicon substrate, and correspondingly, the oxide layer 204 is made of silicon oxide. In other embodiments, the semiconductor substrate 201 is a germanium substrate, and correspondingly, the oxide layer 204 is made of germanium oxide. It is also understood that when the semiconductor substrate 201 is a silicon-germanium substrate, the corresponding oxide layer 204 is made of silicon-germanium oxide.

[0065] In some embodiments, the formed oxide layer 204 may be a gate oxide layer.

[0066] Oxidation treatment 23 can remove the native oxide layer 202 and obtain a gate oxide layer with uniform thickness and high quality. The gate oxide layer plays an important role in controlling the gate switch, and the breakdown and leakage of the gate oxide layer are important factors that hinder the development of semiconductor integrated circuits. Improving the quality of the gate oxide layer can greatly improve its performance. The gate oxide layer obtained by oxidation treatment 23 has uniform thickness and high quality, which can improve the electrical performance and reliability of semiconductor devices.

[0067] In some embodiments, the oxidation process 23 includes a first oxidation step and a second oxidation step performed sequentially.

[0068] Specifically, since the method for growing oxide layer 204 involves oxidizing semiconductor substrate 201 using an in-situ water vapor generation oxidation method (23), in the initial stage of oxidation treatment 23, when the primary oxide layer 202 is relatively thick, hydrogen and oxygen have difficulty penetrating the primary oxide layer 202 to contact semiconductor substrate 201. Therefore, the first oxidation step mainly involves the removal of the primary oxide layer 202. As oxidation treatment 23 progresses, the thickness of the primary oxide layer 202 decreases, and hydrogen and oxygen can more easily penetrate the primary oxide layer 202 to contact semiconductor substrate 201. Therefore, the second oxidation step mainly involves the growth of oxide layer 204.

[0069] In some embodiments, the hydrogen flow rate in the first oxidation step is greater than that in the second oxidation step, and the process temperature used in the first oxidation step is lower than that used in the second oxidation step. Since the first oxidation step of oxidation treatment 23 mainly involves the removal of the primary oxide layer 202, which requires a sufficient amount of hydrogen, the relatively large hydrogen flow rate in the first oxidation step helps ensure a relatively large flow rate of hydrogen needed to remove the primary oxide layer 202, thereby improving the ability to remove the primary oxide layer 202. In contrast, the second oxidation step mainly involves the growth of the oxide layer 204, which requires the participation of oxygen and water; therefore, the hydrogen flow rate in the second oxidation step is relatively small. Since the first oxidation step of oxidation treatment 23 mainly removes the native oxide layer 202, the process temperature adopted in the first oxidation step should be conducive to the removal of the native oxide layer 202; while the second oxidation step mainly grows the oxide layer 204, and oxygen and hydrogen need to pass through the remaining native oxide layer 202 to contact the semiconductor substrate 201, and the process temperature adopted in the second oxidation step should be conducive to the formation of the oxide layer 204. Therefore, the process temperature adopted in the second oxidation step is relatively high.

[0070] In some embodiments, the hydrogen flow rate in the first oxidation step can be 1.005 to 1.05 times the hydrogen flow rate in the second oxidation step. For example, the hydrogen flow rate in the first oxidation step can be 1.01, 1.02, or 1.04 times the hydrogen flow rate in the second oxidation step.

[0071] The first oxidation step uses a relatively high hydrogen flow rate to remove most of the native oxide layer 202, resulting in a relatively thin remaining native oxide layer 202. The second oxidation step uses a relatively low hydrogen flow rate for the growth of the oxide layer 204 and the removal of the remaining native oxide layer 202. The use of a relatively high hydrogen flow rate in the first oxidation step to reduce the thickness of the native oxide layer 202 as much as possible helps to reduce the difficulty for hydrogen and oxygen to penetrate the native oxide layer 202 and contact the semiconductor substrate 201 in the second oxidation step, thus shortening the process time of the second oxidation step. Conversely, the second oxidation step requires relatively less hydrogen, and using a relatively low hydrogen flow rate reduces process costs.

[0072] Specifically, the hydrogen flow rate in the first oxidation step is 0.1005 slm to 2.1 slm (Standard Liter per Minute), for example, the hydrogen flow rate in the first oxidation step can be 0.5 slm, 1 slm, or 2.0 slm, and the hydrogen flow rate in the second oxidation step is 0.1 slm to 2 slm, for example, the hydrogen flow rate in the second oxidation step can be 0.4 slm, 0.8 slm, or 1.8 slm.

[0073] The first oxidation step uses a relatively low process temperature, which is suitable for removing the primary oxide layer 202 so that most of the primary oxide layer 202 can be converted and removed. The second oxidation step uses a relatively high process temperature, which accelerates the passage of hydrogen and oxygen through the primary oxide layer 202 and shortens the process time.

[0074] Specifically, the process temperature used in the first oxidation step is 400℃ to 600℃, for example, the process temperature used in the first oxidation step can be 450℃, 500℃ or 550℃; the process temperature used in the second oxidation step is 900℃ to 1100℃, for example, the process temperature used in the second oxidation step can be 900℃, 1000℃ or 1100℃.

[0075] In some embodiments, the process parameters of the oxidation treatment 23 further include: the oxygen flow rate is 10 slm to 30 slm, for example, the oxygen flow rate can be 10 slm, 20 slm or 30 slm; and the chamber pressure is 8 torr to 20 torr, for example, the chamber pressure can be 8 torr, 15 torr or 20 torr.

[0076] Subsequent process steps may also include: forming a gate electrode layer on the surface of the oxide layer 204; and forming source / drain doped regions in the semiconductor substrate 201 on opposite sides of the gate electrode layer.

[0077] The semiconductor device fabrication method provided in this disclosure involves doping a semiconductor substrate with a native oxide layer with fluorine ions to enrich the native oxide layer with fluorine ions, and then oxidizing the semiconductor substrate located at the bottom of the native oxide layer to form an oxide layer. The gas used in the oxidation process reacts with the fluorine-rich native oxide layer to convert the native oxide layer into gaseous byproducts, thereby removing the native oxide layer. In this way, the native oxide layer can be removed as much as possible and a high-quality oxide layer can be formed, thereby improving the reliability and electrical performance of the semiconductor device.

[0078] Those skilled in the art will understand that the above embodiments are specific examples of implementing this disclosure, and in practical applications, various changes in form and detail may be made without departing from the spirit and scope of this disclosure. Any person skilled in the art can make their own modifications and alterations without departing from the spirit and scope of this disclosure; therefore, the scope of protection of this disclosure should be determined by the scope defined in the claims.

Claims

1. A method for fabricating a semiconductor device, characterized in that, include: A semiconductor substrate is provided, wherein a native oxide layer is formed on the surface of the semiconductor substrate; The original oxide layer is doped with fluorine ions; The semiconductor substrate located at the bottom of the primary oxide layer is oxidized to form an oxide layer, and the gas used in the oxidation process reacts with the primary oxide layer to convert the primary oxide layer into gaseous byproducts, thereby removing the primary oxide layer.

2. The method for fabricating a semiconductor device according to claim 1, characterized in that, The method for fluorine ion doping includes: providing a fluorine-containing gas; performing decoupled plasma treatment on the fluorine-containing gas to form a fluorine plasma; and injecting the fluorine plasma into the native oxide layer.

3. The method for fabricating a semiconductor device according to claim 2, characterized in that, The fluorine-containing gas includes fluorine-containing compounds that are gaseous at room temperature.

4. The method for preparing a semiconductor device according to claim 3, wherein the fluorine-containing compound includes XeF2.

5. The method for fabricating a semiconductor device according to claim 2, characterized in that, The process parameters used for fluorine ion doping include: a power supply of 1500W to 2200W, a power supply duty cycle of 10% to 50%, and a chamber pressure of 10mt to 50mt.

6. The method for fabricating a semiconductor device according to claim 1, characterized in that, The method for fluorine ion doping includes: forming a fluorine-containing doped layer on the surface of the native oxide layer; performing an annealing treatment to allow fluorine ions in the fluorine-containing doped layer to diffuse into the native oxide layer; and removing the fluorine-containing doped layer.

7. The method for fabricating a semiconductor device according to claim 6, characterized in that, The annealing process includes microwave annealing, flash annealing, or laser annealing.

8. The method for fabricating a semiconductor device according to claim 1, characterized in that, The oxidation process uses gases including hydrogen and oxygen.

9. The method for fabricating a semiconductor device according to claim 1 or 8, characterized in that, The primary oxide layer is made of silicon oxide; hydrofluoric acid is formed during the oxidation process, and the hydrofluoric acid reacts with the primary oxide layer to convert the primary oxide layer into gaseous fluorosilicone compounds and water vapor.

10. The method for fabricating a semiconductor device according to claim 1, wherein the oxidation treatment employs an in-situ water vapor generation oxidation method.

11. The method for fabricating a semiconductor device according to claim 8, characterized in that, The oxidation process includes a first oxidation step and a second oxidation step performed sequentially, wherein the flow rate of hydrogen in the first oxidation step is greater than the flow rate of hydrogen in the second oxidation step, and the process temperature used in the first oxidation step is lower than the process temperature used in the second oxidation step.

12. The method for fabricating a semiconductor device according to claim 11, characterized in that, The hydrogen flow rate in the first oxidation step is 1.005 to 1.05 times the hydrogen flow rate in the second oxidation step.

13. The method for fabricating a semiconductor device according to claim 11, characterized in that, The flow rate of hydrogen in the second oxidation step is 0.1 slm to 2 slm.

14. The method for fabricating a semiconductor device according to claim 11, characterized in that, The oxygen flow rate during the oxidation process is 10 slm to 30 slm.

15. The method for fabricating a semiconductor device according to claim 11, characterized in that, The process temperature used in the first oxidation step is 400℃~600℃; the process temperature used in the second oxidation step is 900℃~1100℃.

16. The method for fabricating a semiconductor device according to claim 1 or 11, characterized in that, During the oxidation process, the chamber pressure is 8 to 20 torr.

17. The method for fabricating a semiconductor device according to claim 1, characterized in that, Before performing the fluorine ion doping, the process further includes: pre-cleaning the native oxide layer to reduce its thickness.

18. The method for fabricating a semiconductor device according to claim 1, characterized in that, The oxide layer is a gate oxide layer.

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