Method for manufacturing a semiconductor structure and semiconductor structure

Abstract

The application belongs to the technical field of semiconductor, and particularly relates to a preparation method of a semiconductor structure and the semiconductor structure, which are used for solving the technical problem of large oxide thickness of the semiconductor structure. The preparation method of the semiconductor structure comprises the following steps: providing a substrate, the substrate comprising a device region and a shallow trench isolation region, the shallow trench isolation region surrounding the device region, and the device region being exposed to a substrate surface; depositing a barrier layer on the substrate, the barrier layer covering at least the device region; forming an initial oxide, the initial oxide being located in the device region and being in contact with the barrier layer; and removing part of the initial oxide to form a device oxide. When the initial oxide is formed, the barrier layer is used to shield the device region, so that the growth rate of the initial oxide can be slowed down, the thickness of the initial oxide can be controlled, a thinner initial oxide can be formed, and finally a thinner device oxide can be formed. In addition, the device oxide is formed after part of the initial oxide is removed, so that the thickness of the device oxide is further reduced.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a method for preparing a semiconductor structure and a semiconductor structure. Background Technology

[0002] With the continuous development of technology, the application of semiconductor structures is becoming increasingly widespread. Fields such as computers and communications require semiconductor structures with different functions. In these semiconductor structures, oxides are typically fabricated to serve as interlayer insulation. For example, gate oxide is usually formed near the gate of a semiconductor structure.

[0003] Oxides are typically silicon oxide, which possesses relatively stable chemical properties and insulating properties, and can prevent impurities from entering, making it widely used in semiconductor structures. In related technologies, oxides can be formed on substrates through oxidation processes. For example, oxides are often formed on substrates using in-situ steam generation (ISSG) technology, which uses oxygen doped with a small amount of hydrogen as the reactant gas. At high temperatures, hydrogen and oxygen undergo a combustion-like chemical reaction, producing a large number of gaseous reactive radicals. These radicals then oxidize the substrate to form the oxide.

[0004] Oxides formed using in-situ water vapor generation processes generally exhibit good density and are less prone to breakdown. However, as the size of semiconductor structures continues to shrink, the required oxide thickness also decreases to achieve the desired electrical properties (e.g., lower threshold voltage in transistor structures). However, because the reaction temperature of in-situ water vapor generation processes is generally high, and the film formation rate is typically fast, the oxide thickness generated using this method is generally large, making it difficult to meet the requirements. Summary of the Invention

[0005] In view of this, embodiments of the present invention provide a method for preparing a semiconductor structure and a semiconductor structure to solve the technical problem of large oxide thickness in semiconductor structures.

[0006] In a first aspect, embodiments of the present invention provide a method for fabricating a semiconductor structure, comprising: providing a substrate, the substrate including a device region and a shallow trench isolation region, the shallow trench isolation region surrounding the device region and the device region being exposed on the surface of the substrate; depositing a barrier layer on the substrate, the barrier layer at least covering the device region; forming an initial oxide located within the device region and in contact with the barrier layer; and removing a portion of the initial oxide to form a device oxide.

[0007] The method for preparing the semiconductor structure provided in this invention has the following advantages:

[0008] In the semiconductor structure fabrication method provided in this embodiment of the invention, a substrate is first provided, which includes a device region and a shallow trench isolation region surrounding the device region. The device region is exposed on the substrate surface to facilitate the subsequent formation of a device oxide. Then, a barrier layer is deposited on the substrate, which at least covers the device region to shield it. Next, an initial oxide is formed, located within the device region and in contact with the barrier layer. By utilizing the shielding effect of the barrier layer on the device region, the growth rate of the initial oxide is slowed down during its formation, making it easier to control its thickness. Consequently, the initial oxide has a smaller thickness, resulting in a thinner final device oxide. Then, a portion of the initial oxide is removed to form the device oxide. By thinning the initial oxide, the thickness of the final device oxide is further reduced, resulting in a thinner device oxide.

[0009] In the semiconductor structure fabrication method described above, the thickness of the device oxide is 1 nm-3 nm.

[0010] In the semiconductor structure fabrication method described above, the device oxide is silicon oxide.

[0011] In the semiconductor structure fabrication method described above, the thickness of the initial oxide is less than or equal to 6 nm.

[0012] In the semiconductor structure fabrication method described above, the step of forming the initial oxide includes: thermally oxidizing the device region using an in-situ water vapor generation process to form the initial oxide.

[0013] In the semiconductor structure fabrication method described above, the temperature of the in-situ water vapor generation process is 1000℃-1500℃.

[0014] In the semiconductor structure fabrication method described above, after the step of forming the initial oxide and before the step of removing a portion of the initial oxide, the method further includes: removing the barrier layer using an etching process.

[0015] In the semiconductor structure fabrication method described above, after the step of forming the initial oxide and before the step of removing the barrier layer using an etching process, the method further includes: performing a nitriding treatment on the initial oxide.

[0016] In the semiconductor structure fabrication method described above, the step of removing a portion of the initial oxide includes: removing a portion of the initial oxide away from the substrate using a diluted hydrofluoric acid solution.

[0017] In the semiconductor structure preparation method described above, the mass ratio of hydrofluoric acid to deionized water in the diluted hydrofluoric acid solution ranges from 1:500 to 1:2000.

[0018] In the semiconductor structure fabrication method described above, the barrier layer is a silicon nitride layer or a silicon oxynitride layer.

[0019] In the semiconductor structure fabrication method described above, the thickness of the barrier layer is 5nm-10nm.

[0020] In the semiconductor structure fabrication method described above, the step of depositing a barrier layer on the substrate includes: depositing the barrier layer on the substrate by an atomic layer deposition process.

[0021] In the semiconductor structure fabrication method described above, the material of the shallow trench isolation region includes silicon oxide.

[0022] In a second aspect, embodiments of the present invention provide a semiconductor structure including a substrate, the substrate including a device region and a shallow trench isolation region, the shallow trench isolation region surrounding the device region, the device region being exposed on the surface of the substrate; and a device oxide located within the device region, the device oxide having a thickness of 1 nm-3 nm.

[0023] The semiconductor structure provided in this embodiment of the invention includes a substrate, which includes a device region and a shallow trench isolation region surrounding the device region. The device region is exposed on the surface of the substrate, and a device oxide is formed in the device region. The thickness of the device oxide is 1nm-3nm, which is relatively small, thus giving the semiconductor structure the advantage of a small oxide thickness.

[0024] In addition to the technical problems solved by the embodiments of the present invention, the technical features constituting the technical solutions, and the beneficial effects brought about by the technical features of these technical solutions described above, the semiconductor structure preparation method and semiconductor structure provided by the embodiments of the present invention, other technical problems that can be solved by the semiconductor structure, other technical features included in the technical solutions, and the beneficial effects brought about by these technical features will be further explained in detail in the specific embodiments. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. It is obvious that the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1This is a flowchart of the semiconductor structure fabrication method in an embodiment of the present invention;

[0027] Figure 2 This is a schematic diagram of the substrate structure in an embodiment of the present invention;

[0028] Figure 3 This is a schematic diagram of the structure after the barrier layer is formed in an embodiment of the present invention;

[0029] Figure 4 This is a schematic diagram of the structure after the initial oxide is formed in an embodiment of the present invention;

[0030] Figure 5 This is a schematic diagram of the structure of the removal layer in an embodiment of the present invention;

[0031] Figure 6 This is a schematic diagram of the structure after removing part of the initial oxide in an embodiment of the present invention;

[0032] Figure 7 This is a schematic diagram of the structure after removing the blocking layer in an embodiment of the present invention;

[0033] Figure 8 This is a schematic diagram of the structure after the formation of the nitriding layer in an embodiment of the present invention;

[0034] Figure 9 This is a schematic diagram of the structure after the partial nitriding layer is formed in an embodiment of the present invention.

[0035] Explanation of reference numerals in the attached figures:

[0036] 10-Base;

[0037] 11-Device region;

[0038] 12- Shallow trench isolation area;

[0039] 20-Blocking layer;

[0040] 30 - Initial oxide;

[0041] 40 - Device oxides;

[0042] 50 - Remove layer;

[0043] 60-Nitrided layer. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.

[0045] Semiconductor structures typically incorporate device oxides for interlayer insulation; for example, a gate oxide film is usually formed on the gate of a transistor element. The device oxide can be silicon oxide, and in related technologies, it is generally formed using an in-situ moisture generation process.

[0046] However, in the process of forming device oxides using in-situ water vapor generation technology, the reaction temperature is generally high, and the film formation rate is usually fast, making it difficult to control the film thickness. The resulting device oxides are generally quite thick, rarely reaching thicknesses below 3 nm. Furthermore, the performance of the resulting device oxides is also poor, with a low breakdown voltage (BV) and a high defect density of states (DIT).

[0047] This invention provides a method for fabricating a semiconductor structure. By forming a barrier layer covering the device region on a substrate, the barrier layer can slow down the growth rate of the initial oxide during subsequent formation of the initial oxide in the device region, thereby controlling the thickness of the initial oxide and forming a thinner initial oxide, which in turn forms a thinner device oxide. Furthermore, removing a portion of the initial oxide, i.e., thinning the initial oxide to obtain the device oxide, further reduces the thickness of the device oxide.

[0048] Example 1

[0049] Reference Figure 1 , Figure 1 This invention provides a method for fabricating a semiconductor structure, which can be used to fabricate device oxides with small thicknesses. The method specifically includes the following steps:

[0050] S101: Provides a substrate, the substrate including a device region and a shallow trench isolation region surrounding the device region, the device region being exposed on the substrate surface.

[0051] Reference Figure 2The substrate 10 includes a device region 11 and a shallow trench isolation (STI) region 12. The shallow trench isolation region 12 may surround the device region 11 to isolate and protect the components in the device region 11. For example, the shallow trench isolation region 12 may isolate and protect devices such as MOS transistors (Metal-Oxide-Semiconductor field-effect transistors) formed in the device region.

[0052] In some possible examples, the shallow trench isolation region 12 can be formed by etching the substrate 10 to form a trench structure, filling the trench structure with oxide, and planarizing the filled oxide. The material of the shallow trench isolation region 12 may include silicon oxide (SiO2) or hafnium oxide (HfO2). This embodiment of the invention does not limit this.

[0053] Continue to refer to Figure 2 The upper surface of device region 11 can be flush with the upper surface of shallow trench isolation region 12, exposing device region 11 to the surface of substrate 10, facilitating oxidation treatment of device region 11. The material of device region 11 can include silicon (Si) or hafnium (Hf), such as monocrystalline silicon or polycrystalline silicon. Device oxide 40 can include silicon oxide or hafnium oxide.

[0054] For ease of description, the embodiments of the present invention and the following embodiments are described in detail with the device region 11 being made of silicon and the shallow trench isolation region 12 being made of silicon oxide as an example.

[0055] S102: Deposit a barrier layer on the substrate, the barrier layer covering at least the device area.

[0056] In some possible examples, a barrier layer 20 is formed on the substrate 10 by a deposition process, such as chemical vapor deposition (CVD), physical vapor deposition (PVD), or atomic layer deposition (ALD). Figure 3 The barrier layer 20 is shown. In this embodiment of the invention, the barrier layer 20 is deposited on the substrate 10 by atomic layer deposition. The formed barrier layer 20 has a uniform thickness and good consistency, which allows for better control of the thickness of the device oxide during the subsequent formation of the device oxide.

[0057] The barrier layer 20 covers the device region 11, shielding it and isolating some oxygen. The barrier layer 20 may only cover the device region 11, i.e., the barrier layer 20 is opposite to the device region 11; or the barrier layer 20 may cover the entire substrate 10, i.e., the barrier layer 20 is opposite to the substrate 10. Figure 3 As shown, the barrier layer 20 is formed on the entire upper surface of the substrate 10.

[0058] The barrier layer 20 can be a silicon nitride (SiN) layer or a silicon oxynitride (SiON) layer. For example, in this embodiment of the invention, the barrier layer 20 is a silicon nitride layer. The thickness of the barrier layer 20 can be 5nm-10nm. With this setting, the internal stress of the barrier layer 20 is relatively small, and the barrier effect of the barrier layer 20 is better. If the thickness of the barrier layer 20 is too small, it is easy to cause the thickness of the initially formed oxide to be too large, which does not meet the requirements, and nitrogen will penetrate into the substrate 10 during the subsequent nitriding process. If the thickness of the barrier layer 20 is too large, it is easy to cause the thickness of the initially formed oxide to be too small, making it difficult to control the thickness of the final device oxide, and the concentration of nitrogen doped into the initial oxide during the subsequent nitriding process is too low, which does not meet the device requirements.

[0059] It should be noted that the barrier layer 20 can be Figure 3 The single-layer structure shown can also be a multi-layer structure, and the embodiments of the present invention are not limited thereto. For example, the barrier layer 20 may include a stacked silicon nitride layer and / or a silicon oxynitride layer.

[0060] S103: Formation of initial oxide, which is located within the device region and in contact with the barrier layer.

[0061] The initial oxide 30 can be silicon oxide, which can be formed by oxidizing the device region 11. In some possible examples, the device region 11 is thermally oxidized using an in-situ moisture generation process, causing the portion of the device region 11 near the barrier layer 20 to be converted into oxide, forming the initial oxide 30. The formed initial oxide 30 is located within the device region 11 and is in contact with the barrier layer 20. Figure 4 As shown, the upper part of device region 11 is oxidized to form initial oxide 30.

[0062] In the process of forming the initial oxide 30 through in-situ water vapor generation, the process temperature can be 1000℃~1500℃ to make the generated initial oxide 30 have a relatively dense structure and good performance. The oxidizing gas can be oxygen (O2), a mixture containing oxygen, nitrous oxide (N2O), or a mixture containing nitrous oxide. Of course, the embodiments of the present invention are not limited to this, and the initial oxide 30 in the embodiments of the present invention can also be formed by other oxidation processes.

[0063] In the above process, by using the barrier layer 20 to shield the device region 11, the growth rate of the initial oxide 30 can be slowed down, making it easier to control the thickness of the initial oxide 30, thereby forming a thinner initial oxide 30, so that the final device oxide 40 is thinner.

[0064] It is understandable that the growth rate of the initial oxide 30 is related to the thickness of the barrier layer 20. The greater the thickness of the barrier layer 20, the slower the growth rate of the initial oxide 30; the smaller the thickness of the barrier layer 20, the faster the growth rate of the initial oxide 30.

[0065] In this embodiment of the invention, the growth rate of the initial oxide 30 can be controlled by adjusting the thickness of the barrier layer 20 to generate an initial oxide 30 with a smaller thickness. For example, the thickness of the initial oxide 30 can be less than or equal to 6 nm. With this configuration, in the subsequent process of forming the device oxide, a device oxide of the desired thickness can be obtained by removing less of the initial oxide 30, making it easier to control the thickness of the device oxide.

[0066] It should be noted that the initial oxide 30 is formed in Figure 4 The initial oxide 30 can also be formed between the two shallow trench isolation regions 12 shown. Figure 4 The initial oxide 30 can also be formed on the outer side of the two shallow trench isolation regions 12 shown, that is, on the base portion located on the left and right sides.

[0067] S104: Removes part of the initial oxide to form device oxide.

[0068] In this embodiment of the invention, a portion of the initial oxide 30 is removed to further thin the initial oxide 30. After removing the portion of the initial oxide 30, a device oxide 40 is formed, and the obtained device oxide 40 is relatively thin.

[0069] In some possible examples, the portion of the initial oxide 30 that is far from the substrate 10 is removed, such as... Figure 5 As shown, the portion of the initial oxide 30 above the dashed line is removed, i.e., the portion located... Figure 5 The base above the dashed line shown is the removal layer 50 that needs to be removed. For example... Figure 6 As shown, after removing part of the initial oxide 30, device oxide 40 is formed. The thickness of device oxide 40 can be 1nm-3nm, and the thickness of device oxide 40 is relatively small.

[0070] In this embodiment of the invention, a portion of the initial oxide 30 can be removed by wet etching. For example, a diluted hydrofluoric acid (DHF) solution is used as the etching solution. The mass ratio of hydrofluoric acid (HF) to deionized water (DIW) in the diluted hydrofluoric acid solution ranges from 1:500 to 1:2000. Using a low-concentration diluted hydrofluoric acid solution can reduce or avoid damage to the portion of the device region 11 located below the initial oxide 30.

[0071] In the semiconductor structure fabrication method provided in this embodiment of the invention, a substrate 10 is first provided. The substrate 10 includes a device region 11 and a shallow trench isolation region 12. The shallow trench isolation region 12 surrounds the device region 11, and the device region 11 is exposed on the surface of the substrate 10 to facilitate the subsequent formation of a device oxide 40 within the device region 11. Then, a barrier layer 20 is deposited on the substrate 10. The barrier layer 20 at least covers the device region 11, thereby shielding the device region 11. Subsequently, an initial oxide 30 is formed, located within the device region 11 and in contact with the barrier layer 20. The barrier layer 20 is then used to... The shielding effect on device region 11 can slow down the growth rate of the initial oxide 30, making it easier to control the thickness of the initial oxide 30, thus forming a thinner initial oxide 30. With this setting, in the subsequent process of forming device oxide 40, the required thickness of device oxide 40 can be obtained by removing less of the initial oxide 30, and the thickness of device oxide 40 is easier to control. Further removal of some initial oxide 30 to form device oxide 40, by thinning the initial oxide 30, further reduces the thickness of the final device oxide 40, making the thickness of device oxide 40 smaller.

[0072] Reference Figure 7 After the step of forming the initial oxide 30 and before the step of removing part of the initial oxide 30, the method for preparing the semiconductor structure in the embodiments of the present invention further includes: removing the barrier layer 20 by means of an etching process.

[0073] This configuration exposes the substrate 10 and the initial oxide 30 formed therein, facilitating subsequent processing of the initial oxide 30. The barrier layer 20 can be removed by etching, for example, by dry etching or wet etching.

[0074] When the barrier layer 20 is a silicon oxynitride layer, in some possible examples, the barrier layer 20 can be dry-etched using a fluorine-containing gas as the etching gas. For example, the etching gas can be carbon tetrafluoride (CF4) gas.

[0075] After the step of forming the initial oxide 30 and before the step of removing the barrier layer 20 using an etching process, the method for preparing the semiconductor structure in this embodiment of the invention further includes: performing a nitriding treatment on the initial oxide 30.

[0076] In some possible examples, the initial oxide 30 can be subjected to remote plasma nitriding (RPN) using microwaves or decoupled plasma nitriding (DPN) using radio frequency to form the initial oxide 30 doped with nitrogen ions.

[0077] By nitriding the initial oxide 30, its electrical properties can be adjusted. For example, the initial oxide 30 can achieve a higher dielectric constant, resulting in a lower threshold voltage for the transistor device at the same thickness. Furthermore, during subsequent dry etching to thin the initial oxide 30, the etching rate can be reduced, allowing for better control of the etching thickness and reducing or preventing the initial oxide 30 from being etched through, thus avoiding damage to the device region 11.

[0078] It should be noted that it is possible to... Figure 8 As shown, the entire initial oxide 30 is nitrided, meaning the entire initial oxide 30 forms a nitrided layer 60; alternatively, as shown... Figure 9 The initial oxide 30 is shown to be nitrided, that is, the initial oxide 30 at the top is nitrided to form a nitrided layer 60. This is not limited in the embodiments of the present invention.

[0079] During nitriding of the initial oxide 30, the barrier layer 20 formed on the substrate 10 allows nitrogen ions to be diffused into the initial oxide 30 by adjusting the nitriding energy and concentration. During nitriding, the barrier layer 20 blocks some nitrogen ions to control the diffusion depth, thereby facilitating control of the thickness of the nitrided layer 60 and preventing nitrogen ions from damaging the portion of the device region 11 located below the initial oxide 30.

[0080] Example 2

[0081] Reference Figure 6 , Figure 6 This is a schematic diagram of the semiconductor structure in an embodiment of the present invention. The semiconductor structure includes a substrate, which includes a device region 11 and a shallow trench isolation region 12. The shallow trench isolation region 12 may be disposed around the device region 11 to isolate and protect the device region 11. Device oxide 40 is formed in the device region 11.

[0082] Device oxide 40 is exposed on the upper surface of the substrate. The thickness of device oxide 40 can be 1nm-3nm, which is relatively small. The material of device region 11 may include silicon, the material of shallow trench isolation region 12 may include silicon oxide, and the material of device oxide 40 may include silicon oxide.

[0083] In some possible examples, the device oxide 40 can be formed by the following steps: providing a substrate including a device region 11 and a shallow trench isolation region 12 surrounding the device region 11, the device region 11 being exposed to the substrate surface; depositing a barrier layer on the substrate, the barrier layer at least covering the device region 11; forming an initial oxide located within the device region 11 and in contact with the barrier layer; and removing a portion of the initial oxide to form the device oxide.

[0084] By blocking the device region 11 with a barrier layer, the growth rate of the initial oxide can be slowed down, resulting in a thinner initial oxide layer, which in turn makes the final device oxide 40 thinner. Furthermore, removing part of the initial oxide and thinning it further reduces the thickness of the final device oxide 40, making it even thinner.

[0085] It should be noted that the semiconductor structure in the embodiments of the present invention may further include a nitriding layer 60. For example, the device oxide 40 is a nitriding layer 60, that is, the nitriding layer 60 is formed after all the device oxide 40 undergoes nitriding treatment; or, a nitriding layer 60 is disposed on the device oxide 40, that is, the nitriding layer 60 is formed after a portion of the device oxide 40 undergoes nitriding treatment, such as... Figure 9 As shown, the upper part of the device oxide 40 is nitrided to form a nitrided layer 60.

[0086] The semiconductor structure in this embodiment of the invention includes a substrate 10, which includes a device region 11 and a shallow trench isolation region 12 surrounding the device region 11. A device oxide 40 is formed in the device region 11. The device oxide 40 has a thickness of 1nm-3nm, which is relatively small, thus giving the semiconductor structure the advantage of a small thickness of the device oxide 40.

[0087] The various embodiments or implementation methods described in this specification are presented in a progressive manner. Each embodiment focuses on the differences from other embodiments, and the same or similar parts between the embodiments can be referred to each other.

[0088] Those skilled in the art should understand that, in the disclosure of this invention, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the system or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as limiting this invention.

[0089] In the description of this specification, references to "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0090] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for fabricating a semiconductor structure, characterized in that, include: A substrate is provided, the substrate including a device region and a shallow trench isolation region surrounding the device region, the device region being exposed on the surface of the substrate; A barrier layer is deposited on the substrate, the barrier layer at least covering the device region; An initial oxide is formed, which is located within the device region and in contact with the barrier layer; Remove a portion of the initial oxide to form a device oxide; The thickness of the oxide in the device is 1nm-3nm; The steps for forming the initial oxide include: The device region is thermally oxidized using an in-situ water vapor generation process to form the initial oxide. The barrier layer is a silicon nitride layer or a silicon oxynitride layer.

2. The method for preparing a semiconductor structure according to claim 1, characterized in that, The oxide of the device is silicon oxide.

3. The method for preparing a semiconductor structure according to claim 1, characterized in that, The thickness of the initial oxide is less than or equal to 6 nm.

4. The method for preparing a semiconductor structure according to claim 1, characterized in that, The temperature of the in-situ water vapor generation process is 1000℃-1500℃.

5. The method for preparing a semiconductor structure according to claim 1, characterized in that, After the step of forming the initial oxide and before the step of removing a portion of the initial oxide, the method further includes: The barrier layer is removed using an etching process.

6. The method for preparing a semiconductor structure according to claim 5, characterized in that, After the step of forming the initial oxide and before the step of removing the barrier layer using an etching process, the method further includes: The initial oxide was subjected to nitriding treatment.

7. The method for preparing a semiconductor structure according to claim 1, characterized in that, The step of removing part of the initial oxide includes: The initial oxide, located away from the substrate, is removed using a diluted hydrofluoric acid solution.

8. The method for preparing a semiconductor structure according to claim 7, characterized in that, The mass ratio of hydrofluoric acid to deionized water in the diluted hydrofluoric acid solution ranges from 1:500 to 1:2000.

9. The method for preparing a semiconductor structure according to claim 1, characterized in that, The thickness of the barrier layer is 5nm-10nm.

10. The method for preparing a semiconductor structure according to any one of claims 1-8, characterized in that, The step of depositing a barrier layer on the substrate includes: The barrier layer is deposited on the substrate using an atomic layer deposition process.

11. The method for preparing a semiconductor structure according to any one of claims 1-8, characterized in that, The material of the shallow trench isolation area includes silicon dioxide.

12. A semiconductor structure, characterized in that, include: A substrate, the substrate including a device region and a shallow trench isolation region surrounding the device region, the device region being exposed on the surface of the substrate; Device oxide, wherein the device oxide is located within the device region and the thickness of the device oxide is 1 nm-3 nm.

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