Semiconductor device and cleaning method of shallow trench isolation structure

Abstract

The invention discloses a method for cleaning a semiconductor device and a shallow trench isolation structure, and belongs to the technical field of semiconductors, and the method comprises the steps: providing a semiconductor device which comprises a silicon substrate, a multilayer semiconductor structure is stacked on the silicon substrate, in the multilayer semiconductor structure, the surface layer is made of a silicon dioxide material, and the surface layer is made of a silicon oxide material; residues needing to be cleaned exist on the outer surface of the surface layer; processing the outer surface of the surface layer by adopting a plasma nitriding method, so that the outer surface of the surface layer is nitrided to form a silicon oxynitride layer; and etching the silicon oxynitride layer by adopting a sulfuric acid and hydrogen peroxide mixed solution, and stopping etching after the silicon oxynitride layer is removed by etching so as to clean residues on the outer surface of the surface layer. According to the method, silicon dioxide can be cleaned on the premise of controllable silicon dioxide loss.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor, in particular to a semiconductor device, a cleaning method of shallow trench isolation structure and a semiconductor device. BACKGROUND

[0002] In the production process of a semiconductor device, there may be a stage (such as a stage of producing a shallow trench isolation structure) in which the surface of the semiconductor device is silicon dioxide, and there is serious residue on the surface of the silicon dioxide, which needs to be cleaned to improve the production yield of the semiconductor device.

[0003] In the related art, hydrofluoric acid (HF) is usually used to clean the residue on the surface of the silicon dioxide, for example, the silicon dioxide is soaked in a dilute hydrofluoric acid (DHF) solution to clean the residue on the surface of the silicon dioxide.

[0004] However, the etching reaction endpoint of the DHF is difficult to control, and the DHF also reacts with the silicon dioxide, resulting in a large amount of silicon dioxide loss when using the DHF to clean the residue on the surface of the silicon dioxide. SUMMARY

[0005] The present application provides a cleaning method of a semiconductor device and a shallow trench isolation structure, which can clean the silicon dioxide under the premise of controllable silicon dioxide loss. The technical solution at least includes the following schemes: In a first aspect, a cleaning method of a semiconductor device is provided, comprising: providing a semiconductor device, the semiconductor device comprising a silicon substrate, and a multilayer semiconductor structure stacked on the silicon substrate, wherein a surface layer of the multilayer semiconductor structure is made of silicon dioxide, and there is residue on the outer surface of the surface layer that needs to be cleaned; using a plasma nitridation method to process the outer surface of the surface layer, so that the outer surface of the surface layer is nitrided to form a silicon oxynitride layer; and using a sulfuric acid hydrogen peroxide mixed solution to etch the silicon oxynitride layer, and stopping etching after the silicon oxynitride layer is etched and removed, so as to clean the residue on the outer surface of the surface layer.

[0006] Optionally, the thickness of the silicon oxynitride layer is in the range of 1 to 100 .

[0007] Optionally, the thickness of the silicon oxynitride layer is in the range of 5 to 10 .

[0008] Optionally, in the process of using the plasma nitridation method to process the outer surface of the surface layer, the concentration of nitrogen element is greater than .

[0009] Optionally, in the mixed solution of sulfuric acid and hydrogen peroxide, the ratio of sulfuric acid to hydrogen peroxide ranges from 10:1 to 1:10, and the temperature of the sulfuric acid ranges from 70℃ to 200℃.

[0010] Optionally, the step of treating the outer surface of the surface layer by the plasma nitriding method comprises: using a plasma generator to realize the plasma nitriding method, wherein the power of the plasma generator ranges from 500W to 3000W, the working time of the plasma generator ranges from 5 seconds to 50 seconds, and the chamber pressure of the working plasma generator ranges from 5mTorr to 200mTorr.

[0011] Optionally, after the step of stopping etching after the mixed solution of sulfuric acid and hydrogen peroxide is used to etch the silicon oxynitride layer, the method further comprises: using a water washing method to remove the mixed solution of sulfuric acid and hydrogen peroxide remaining on the surface layer, so as to complete the cleaning of the surface layer.

[0012] The second aspect further provides a cleaning method of a shallow trench isolation structure, comprising the following steps: sequentially depositing a first pad silicon oxide layer and a silicon nitride mask layer on a silicon substrate, and forming a photoresist layer with a shallow trench isolation structure pattern, wherein the first pad silicon oxide layer is made of silicon dioxide; using the photoresist layer as a mask to dry-etch part of the silicon substrate to form a shallow trench; removing the photoresist layer; performing thermal oxidation on the sidewall of the shallow trench to form a second pad silicon oxide layer, wherein the second pad silicon oxide layer is made of silicon dioxide; filling silicon dioxide in the shallow trench by using a chemical vapor deposition method; removing the filled silicon dioxide by using a chemical mechanical polishing process, wherein the chemical mechanical polishing process stops at the silicon nitride mask layer; removing the silicon nitride mask layer by using a phosphoric acid wet etching method to obtain a first shallow trench isolation structure; and cleaning the residues on the outer surface of the first shallow trench isolation structure by using the cleaning method of the semiconductor device according to the first aspect.

[0013] Optionally, the residues on the outer surface of the first shallow trench isolation structure comprise silicon impurities left after the silicon nitride mask layer is removed by using the phosphoric acid wet etching method, and organic matter residues in the grinding liquid after the filled silicon dioxide is removed by using the chemical mechanical polishing process.

[0014] The third aspect further provides a semiconductor device, which is obtained by using the cleaning method of the semiconductor device according to the first aspect or the cleaning method of the shallow trench isolation structure according to the second aspect.

[0015] The technical solution provided by the present application brings at least the following unexpected beneficial effects: Since the residue is attached to the outer surface of the surface layer, and the silicon oxynitride layer includes the outer surface, the outer surface residue can be removed at the same time when the silicon oxynitride layer is etched by the hydrogen peroxide-sulfuric acid mixed solution, so that the surface layer can be cleaned. The hydrogen peroxide-sulfuric acid mixed solution has a large difference in etch rate between SiON and SiO2. At room temperature, the etch rate of the hydrogen peroxide-sulfuric acid mixed solution to SiON is 25 , and the etch rate of the hydrogen peroxide-sulfuric acid mixed solution to SiO2 is almost 0.

[0016] In this case, since the etch rate of the hydrogen peroxide-sulfuric acid mixed solution to SiO2 is very low after the silicon oxynitride layer is etched by the hydrogen peroxide-sulfuric acid mixed solution, the end point of the reaction is easy to control (that is, after the silicon oxynitride layer is etched by the hydrogen peroxide-sulfuric acid mixed solution, the hydrogen peroxide-sulfuric acid mixed solution is not easy to etch SiO2), there is sufficient time for removing the hydrogen peroxide-sulfuric acid mixed solution remaining in the surface layer after the silicon oxynitride layer is etched by the hydrogen peroxide-sulfuric acid mixed solution, and the process of removing the hydrogen peroxide-sulfuric acid mixed solution remaining in the surface layer after the silicon oxynitride layer is etched by the hydrogen peroxide-sulfuric acid mixed solution does not easily cause loss of SiO2.

[0017] Part of the SiO2 is lost in the cleaning process, and the lost SiO2 is the part of SiO2 that is nitrided, and only the part of SiO2 that is nitrided is lost, and there is no other loss of SiO2. Since the part of SiO2 that is nitrided is determined by the plasma nitridation process, and the plasma nitridation process can accurately control the part of SiO2 that is nitrided, the loss of SiO2 in the cleaning process according to the present application is controllable. In this way, the cleaning of SiO2 can be realized under the premise that the loss of SiO2 is controllable. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort based on these drawings.

[0019] Figure 1 A flow chart of a cleaning method of a semiconductor device provided by an exemplary embodiment of the present application is shown; Figure 2 A sectional view of a structure formed by related steps of a cleaning method of a semiconductor device provided by an exemplary embodiment of the present application is shown; Figure 3 A flow chart of a cleaning method of a shallow trench isolation structure provided by an exemplary embodiment of the present application is shown; Figure 4A schematic diagram of a semiconductor device cleaning method for cleaning a shallow trench isolation structure. DETAILED DESCRIPTION

[0020] Unless otherwise defined, technical terms or scientific terms used herein shall have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terms "first", "second", "third", and the like, as used in the description and the claims herein, do not have any specific meaning, and are used only to distinguish one element from another. Similarly, the terms "one", "another", "an", and the like, do not limit the size, number, or quantity of the elements being described, but rather are used only to distinguish one element from another. The terms "comprise", "comprising", "include", "including", and the like, mean including but not limited to. The terms "above", "below", "upper", "lower", and the like, are used only to describe relative positions, and are not used to denote absolute positions. The terms "a", "an", and the like, mean one or more.

[0021] In order to make the objects, technical solutions and advantages of the present application clearer, the following will further describe the embodiments of the present application with reference to the accompanying drawings.

[0022] Figure 1 A flow chart of a semiconductor device cleaning method according to an exemplary embodiment of the present application is shown in FIG. 1. Figure 1 The method comprises the following steps: In step 101, a semiconductor device is provided.

[0023] The semiconductor device comprises a silicon substrate, and a multi-layer semiconductor structure is stacked on the silicon substrate. In the multi-layer semiconductor structure, a surface layer is made of silicon dioxide (SiO2), and a residue to be cleaned exists on the outer surface of the surface layer.

[0024] Here, the surface layer refers to the uppermost layer in the multi-layer semiconductor structure stacked on the silicon substrate, and the outer surface of the surface layer structure directly contacts air.

[0025] Figure 2 A sectional view of the structure formed by the related steps of the semiconductor device cleaning method according to an exemplary embodiment of the present application is shown in FIG. 2. Figure 2 Part (a) of FIG. 2 is a structural schematic diagram of a semiconductor device, as shown in Figure 2 As shown in part (a) of FIG. 2, the semiconductor device comprises a silicon substrate 201, and a multi-layer semiconductor structure 202 is stacked on the silicon substrate. In the multi-layer semiconductor structure, a surface layer 203 is made of silicon dioxide, and a residue to be cleaned exists on the outer surface 204 of the surface layer 203.

[0026] In step 102, the outer surface of the surface layer is treated by plasma nitriding, so that the outer surface of the surface layer is nitrided to form a silicon oxynitride layer.

[0027] Plasma nitriding is a nitriding process that can diffuse nitrogen ions from the outer surface of the surface layer inward, thereby changing the properties of a portion of the surface layer, so that a portion of the surface layer is nitrided to form a nitrided layer. In the embodiments of the present application, the surface layer is made of silicon dioxide, and therefore the nitrided layer formed by nitriding a portion of the surface layer is made of silicon oxynitride (SiON). That is, the outer surface of the surface layer is nitrided to form a silicon oxynitride layer.

[0028] In one possible implementation, the thickness of the silicon oxynitride layer ranges from 1 to 100 . The silicon oxynitride layer is formed by nitriding a portion of the silicon dioxide of the surface layer (the nitrided silicon dioxide is equivalent to the lost silicon dioxide), and the silicon oxynitride also needs to be etched later. If the thickness of the silicon oxynitride layer exceeds 100 , it may result in excessive loss of silicon dioxide, and if the thickness of the silicon oxynitride layer is less than 1 , it may result in incomplete cleaning of some residues due to unevenness of the silicon dioxide surface.

[0029] In another possible implementation, the thickness of the silicon oxynitride layer ranges from 5 to 10 . Controlling the thickness of the silicon oxynitride layer to range from 5 to 10 can prevent excessive loss of silicon dioxide and avoid incomplete cleaning of residues due to the silicon oxynitride layer being too thin.

[0030] Optionally, the concentration of nitrogen elements is greater than during the process of treating the outer surface of the surface layer by plasma nitriding. The concentration of nitrogen elements during the process of treating the outer surface of the surface layer by plasma nitriding affects the formation rate of silicon oxynitride and the uniformity of the structure of the silicon oxynitride layer. By controlling the concentration of nitrogen elements to be greater than , the formation rate of the silicon oxynitride layer can be effectively improved, and the non-uniformity or defects of the generated silicon oxynitride layer can be reduced.

[0031] Optionally, step 102 includes: using a plasma generator to implement plasma nitriding.

[0032] The power range of the plasma generator is 500W to 3000W, the time range of the plasma generator working is 5 seconds to 50 seconds, and the chamber pressure range of the plasma generator working is 5mTorr to 200mTorr. In this way, the working efficiency of the plasma generator and the stability of the generated silicon oxynitride layer can be effectively improved.

[0033] Figure 2 Part (b) of FIG. 1 is a schematic diagram of the surface layer being treated by the plasma nitridation method. As shown in part (b) of FIG. 1, the surface layer 203 is originally made of silicon dioxide, and after the nitridation treatment, part of the surface layer (including the outer surface 204) becomes a silicon oxynitride layer 205. Figure 2

[0034] In step 103, the silicon oxynitride layer is etched by using the sulfuric acid-hydrogen peroxide mixed solution. After the silicon oxynitride layer is etched and removed, the etching is stopped to clean the residual material on the outer surface of the surface layer.

[0035] Since the residual material is attached to the outer surface of the surface layer, and the silicon oxynitride layer includes the outer surface, the residual material on the outer surface can be removed at the same time when the silicon oxynitride layer is etched by using the sulfuric acid-hydrogen peroxide mixed solution, thereby achieving the cleaning of the surface layer.

[0036] Optionally, in the sulfuric acid-hydrogen peroxide mixed solution, the sulfuric acid is concentrated sulfuric acid, and the hydrogen peroxide is electronic grade or reagent grade hydrogen peroxide. The ratio of the sulfuric acid to the hydrogen peroxide is 10:1 to 1:10 (volume ratio). When mixing the sulfuric acid and the hydrogen peroxide, the temperature of the sulfuric acid is 70°C to 200°C, and the hydrogen peroxide can be at room temperature before mixing.

[0037] The sulfuric acid-hydrogen peroxide mixed solution has a large difference in etch rate between SiON and SiO2. At room temperature, the etch rate of the sulfuric acid-hydrogen peroxide mixed solution on SiON is 25 While the etch rate of the sulfuric acid-hydrogen peroxide mixed solution on SiO2 is almost 0.

[0038] In this case, after the silicon oxynitride layer is etched by using the sulfuric acid-hydrogen peroxide mixed solution, the etch rate of the sulfuric acid-hydrogen peroxide mixed solution on SiO2 is extremely low, so the end point of the reaction is easy to control (i.e., after the silicon oxynitride layer is etched by using the sulfuric acid-hydrogen peroxide mixed solution, the sulfuric acid-hydrogen peroxide mixed solution is not easy to etch SiO2), there is sufficient time for removing the sulfuric acid-hydrogen peroxide mixed solution remaining on the surface layer, and the sulfuric acid-hydrogen peroxide mixed solution is not easy to cause loss of silicon dioxide during the process of removing the sulfuric acid-hydrogen peroxide mixed solution remaining on the surface layer after the silicon oxynitride layer is etched by using the sulfuric acid-hydrogen peroxide mixed solution.

[0039] ​Part of the silicon dioxide is lost in the cleaning process, and the lost silicon dioxide is the part of the silicon dioxide that is nitrided, and only the part of the silicon dioxide that is nitrided is lost, and there is no other loss of silicon dioxide. Since the part of the silicon dioxide that is nitrided is determined by the plasma nitriding process, and the plasma nitriding process can accurately control the part of the silicon dioxide that is nitrided, the loss of the silicon dioxide in the cleaning process involved in the embodiment of the present application is controllable. In this way, the cleaning of the silicon dioxide can be realized under the premise that the loss of the silicon dioxide is controllable.

[0040] Figure 2 Part (c) of FIG. 1 shows a schematic diagram of the semiconductor device after the cleaning is completed, as shown in Part (c) of FIG. 1, the silicon oxynitride layer 205 is removed, which is equivalent to the removal of the residue, thereby realizing the cleaning of the semiconductor device. Figure 2

[0041] Optionally, after step 103 is performed, the method further comprises: using a water washing method to remove the residual sulfuric acid and hydrogen peroxide mixed solution on the surface layer, thereby completing the cleaning of the surface layer.

[0042] Here, after the silicon oxynitride layer is etched by using the sulfuric acid and hydrogen peroxide mixed solution, some sulfuric acid and hydrogen peroxide mixed solution will be left on the surface layer, at this time, only the residual sulfuric acid and hydrogen peroxide mixed solution needs to be washed away by using water washing.

[0043] Exemplarily, the semiconductor device can be a semiconductor device with a shallow trench isolation (STI) structure. The following will be described in combination with Figure 3 The flow of the cleaning method of the semiconductor device is shown in the case of the semiconductor device with the STI structure.

[0044] Figure 3 A flowchart of a cleaning method of a shallow trench isolation structure provided by an exemplary embodiment of the present application is shown, referring to FIG. 3. Figure 3 The method comprises: In step 301, a first pad silicon dioxide layer and a silicon nitride mask layer are sequentially deposited on a silicon substrate, and a photoresist layer with a shallow trench isolation structure pattern is formed.

[0045] The first pad silicon dioxide layer is made of silicon dioxide.

[0046] In step 302, the photoresist layer is used as a mask to dry etch part of the silicon substrate to form a shallow trench.

[0047] In step 303, the photoresist layer is removed.

[0048] In step 304, the sidewall of the shallow trench is subjected to thermal oxidation to form a second pad silicon dioxide layer.

[0049] ​The second pad silicon oxide layer is made of silicon dioxide.

[0050] In step 305, the shallow trench is filled with silicon dioxide by chemical vapor deposition.

[0051] In step 306, the filled silicon dioxide is removed by chemical mechanical polishing process, and the chemical mechanical polishing process stops at the silicon nitride mask layer.

[0052] In step 307, the silicon nitride mask layer is removed by phosphoric acid wet etching to obtain the first shallow trench isolation structure.

[0053] As can be seen from the above steps 301 to 307, the oxide filled in the shallow trench isolation structure is silicon dioxide (i.e. step 305), and the oxide filled in the shallow trench isolation structure corresponds to the surface layer in step 101.

[0054] In the process of manufacturing the shallow trench isolation structure, steps 306 and 307 will cause a large amount of residues on the surface of the finally obtained shallow trench isolation structure. The chemical mechanical polishing (CMP) technology in step 306 needs to use a polishing liquid, and after the execution of step 306 is completed, the organic matter in the polishing liquid will be left on the outer surface.

[0055] When phosphoric acid wet etching silicon nitride, high selectivity etching of silicon nitride without damaging other materials is needed, and high concentration of silicon ions can adjust the etching rate of phosphoric acid, so as to optimize the selectivity ratio, so that the phosphoric acid only etches the silicon nitride without damaging other materials. Therefore, after the phosphoric acid wet etching in step 307 is completed, the wafer in the phosphoric acid tank will have silicon impurities.

[0056] In summary, the residues on the outer surface of the first shallow trench isolation structure include: silicon impurities left after the silicon nitride mask layer is removed by phosphoric acid wet etching, and organic matter in the polishing liquid left after the filled silicon dioxide is removed by chemical mechanical polishing process.

[0057] In step 308, the residues on the outer surface of the first shallow trench isolation structure are cleaned.

[0058] In the embodiment of the present application, step 308 is realized by the way in steps 101 to 103.

[0059] Figure 4 A schematic diagram of cleaning the shallow trench isolation structure by the cleaning method of the semiconductor device. Figure 4 Part (a) of FIG. 1 is a schematic diagram of the first shallow trench isolation structure. As shown in FIG. 1(a), the first shallow trench isolation structure is formed on the substrate 100. Figure 4The first shallow trench isolation structure shown in part (a) of FIG. 1 includes: a silicon substrate 401, a shallow trench 402, and a shallow trench isolation structure filled oxide 403 (i.e., silicon dioxide). Here, the silicon substrate 401 corresponds to the silicon substrate 201 in FIG. 2, and the shallow trench isolation structure filled oxide 403 corresponds to the surface layer 203 in FIG. 2. Figure 2 Figure 2 The outer surface 404 of the shallow trench isolation structure filled oxide 403 corresponds to the outer surface 204 of the surface layer 203. The outer surface 204 has the residue that needs to be cleaned.

[0060] In addition, the first pad silicon oxide layer, the second pad silicon oxide layer, and the shallow trench isolation structure filled oxide in the aforementioned steps 301-307 are all silicon dioxide, so the shallow trench isolation structure filled oxide 403 in FIG. 3 is used to represent all of them. Figure 4

[0061] When the shallow trench isolation structure is cleaned by the cleaning method of the semiconductor device, a silicon oxynitride layer is first formed on the surface layer (i.e., the shallow trench isolation structure filled oxide 403) by nitridation. As shown in part (b) of FIG. 1, the shallow trench isolation structure filled oxide 403 is nitrided to form a silicon oxynitride layer 405. Figure 4

[0062] Then, the silicon oxynitride layer is etched by a sulfuric acid hydrogen peroxide mixture solution. After the silicon oxynitride layer is etched and removed, the etching is stopped to clean the residue on the outer surface of the surface layer. As shown in part (c) of FIG. 1, the silicon oxynitride layer is etched, and the outer surface 404 originally having the residue is also removed, that is, the residue on the outer surface of the shallow trench isolation structure filled oxide 403 is cleaned. Figure 4

[0063] The related content of step 308 is described in the aforementioned steps 102-103. The surface layer in steps 102-103 is replaced by the first shallow trench isolation filled oxide, and the detailed description is omitted here.

[0064] Since the thickness of the shallow trench isolation structure filled oxide is usually several thousand angstroms, and the thickness of the silicon oxynitride layer is usually within 100 angstroms, the loss of the silicon dioxide is very small for the entire shallow trench isolation structure filled oxide, that is, the loss is acceptable.

[0065] The embodiment of the present application also provides a semiconductor device obtained by the cleaning method of the semiconductor device or the cleaning method of the shallow trench isolation structure.

[0066] ​​​​The above merely describes optional embodiments of the present application, and is not used to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for cleaning a semiconductor device, characterized in that, The method includes: A semiconductor device is provided, the semiconductor device including a silicon substrate, on which a multilayer semiconductor structure is stacked, wherein the surface layer of the multilayer semiconductor structure is made of silicon dioxide, and the outer surface of the surface layer contains residues that need to be cleaned. The outer surface of the surface layer is treated by plasma nitriding, so that the outer surface of the surface layer is nitrided to form a silicon oxynitride layer; The silicon oxynitride layer is etched using a sulfuric acid and hydrogen peroxide mixture. After the silicon oxynitride layer is etched away, the etching is stopped to clean the outer surface residue of the surface layer.

2. The cleaning method for semiconductor devices according to claim 1, characterized in that, The thickness of the silicon oxynitride layer is in the range of 1. Up to 100 .

3. The cleaning method for semiconductor devices according to claim 1, characterized in that, The thickness of the silicon oxynitride layer is in the range of 5. Up to 10 .

4. The cleaning method for semiconductor devices according to claim 2 or 3, characterized in that, During the treatment of the outer surface of the surface layer using plasma nitriding, the nitrogen concentration is greater than... .

5. The method for cleaning semiconductor devices according to claim 1, characterized in that, In the sulfuric acid and hydrogen peroxide mixed solution, the ratio of sulfuric acid to hydrogen peroxide ranges from 10:1 to 1:10, and the temperature of the sulfuric acid ranges from 70°C to 200°C.

6. The method for cleaning semiconductor devices according to claim 1, characterized in that, The step of treating the outer surface of the surface layer using plasma nitriding to form a silicon oxynitride layer includes: The plasma nitriding method is implemented using a plasma generator with a power range of 500W to 3000W, an operating time range of 5 seconds to 50 seconds, and a chamber pressure range of 5 mTorr to 200 mTorr.

7. The cleaning method for semiconductor devices according to claim 1, characterized in that, After the step of using a sulfuric acid-hydrogen peroxide mixture to etch the silicon oxynitride layer, and stopping the etching process after the silicon oxynitride layer has been etched away, the method further includes: The surface layer is cleaned by washing with water to remove the residual sulfuric acid and hydrogen peroxide mixture.

8. A cleaning method for a shallow trench isolation structure, characterized in that, The method includes: A first pad silicon oxide layer and a silicon nitride mask layer are sequentially deposited on a silicon substrate, and a photoresist layer with a shallow trench isolation structure pattern is formed. The first pad silicon oxide layer is made of silicon dioxide. Using the photoresist layer as a mask, a portion of the silicon substrate is dry-etched to form shallow trenches; Remove the photoresist layer; The sidewalls of the shallow trench are thermally oxidized to form a second pad silicon oxide layer, which is made of silicon dioxide. Silica was filled into the shallow trench using chemical vapor deposition. The filled silicon dioxide is removed by a chemical mechanical polishing process, which stops at the silicon nitride mask layer; The silicon nitride mask layer was removed by wet etching with phosphoric acid to obtain the first shallow trench isolation structure. The residue on the outer surface of the first shallow trench isolation structure is cleaned using the method described in any one of claims 1 to 7.

9. The cleaning method for the shallow trench isolation structure according to claim 8, characterized in that, The residues on the outer surface of the first shallow trench isolation structure include: silicon impurities left after removing the silicon nitride mask layer by phosphoric acid wet etching, and organic residues in the polishing slurry after removing the filled silicon dioxide by chemical mechanical polishing.

10. A semiconductor device, characterized in that, The semiconductor device is obtained by the cleaning method of any one of claims 1 to 7, or the semiconductor device is obtained by the cleaning method of the shallow trench isolation structure of any one of claims 8 to 9.

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