Method for forming silicon thin film

Abstract

The forming method of the silicon thin film comprises the following steps: providing a substrate; depositing and forming a first silicon thin film on the substrate; performing oxidation treatment on the surface of the first silicon thin film to form a silicon oxide layer; and a second silicon film is grown on the silicon oxide layer, and crystal grains of the first silicon film and the second silicon film are hemispherical. According to the method, the silicon film with the hemispherical crystal grains and good uniformity is formed on the substrate, so that the yield of products is improved, and the method is simple and convenient to prepare, easy to control and suitable for large-scale production and manufacturing.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor manufacturing, and in particular to a method for forming a silicon thin film. Background Art

[0002] At present, thin film crystal structures are often formed on semiconductor substrates to control the performance of semiconductors. Silicon thin films are composed of many small silicon grains with different crystal orientations. The grains can be combined to form polycrystalline silicon. Polycrystalline silicon is an important semiconductor material and plays an important role in semiconductor manufacturing processes.

[0003] Currently, silicon thin films are commonly deposited by LPCVD (low-pressure chemical vapor deposition). Most LPCVD silicon thin films are produced in a furnace with a silane atmosphere at around 600 degrees Celsius. The resulting grains have different shapes and sizes and poor uniformity.

[0004] Therefore, it is urgent to provide an improved method for forming a silicon thin film to overcome the above defects. Summary of the invention

[0005] The purpose of the present invention is to provide an improved method for forming a silicon thin film, which forms a silicon thin film with hemispherical grains with good uniformity on a substrate, thereby improving the yield of the product. Moreover, the method is simple to prepare and easy to control, and is suitable for large-scale production.

[0006] To achieve the above object, the method for forming a silicon thin film of the present invention comprises the following steps:

[0007] providing a substrate;

[0008] Depositing a first silicon thin film on the substrate;

[0009] Performing oxidation treatment on the surface of the first silicon film to form a silicon oxide layer;

[0010] A second silicon thin film is grown on the silicon oxide layer, wherein the crystal grains of the first silicon thin film and the second silicon thin film are hemispherical.

[0011] Compared with the prior art, the present invention first deposits a first silicon film on a substrate, for example, by hot wire vapor deposition (HWCVD). During the deposition process, since HWCVD uses a high carbon electrode, the deposited silicon material is relatively carbon-rich, and the morphology of the film can be well controlled. Then, the surface of the first silicon film is oxidized to form a silicon oxide layer, and then a second silicon film is grown on the silicon oxide layer, for example, by HWCVD, so that the grains of the first silicon film and the second silicon film can be well controlled to be hemispherical. The grain uniformity of the first silicon film and the second silicon film is good, which improves the performance of the substrate and the yield rate. Moreover, the first silicon film and the second silicon film are regulated by the silicon oxide layer, which is more conducive to the performance of the substrate. The formation methods of the first silicon film and the second silicon film are similar, and only some parameters need to be changed. The preparation is simple and easy to control, and it is suitable for large-scale production.

[0012] Preferably, the substrate is a single crystal silicon substrate.

[0013] In a preferred embodiment, the method further comprises: forming the first silicon thin film by hot-wire vapor deposition.

[0014] Preferably, in the hot filament vapor deposition, SiH4 gas is used, and the flow rate of the SiH4 gas is 0.2-0.6 sccm.

[0015] Preferably, in the hot wire vapor deposition, the operating power is controlled to be 30-50W.

[0016] Preferably, the oxidation treatment includes wet oxidation and dry oxidation.

[0017] Preferably, the thickness of the silicon oxide layer is 10-20 nm.

[0018] In another preferred embodiment, the method further comprises: forming the second silicon film by hot-wire vapor deposition.

[0019] Preferably, in the hot filament vapor deposition, SiH4 gas and H2 gas are used, the flow rate of the SiH4 gas is 0.2-0.6 sccm, and the flow rate of the H2 gas is 0.6-0.8 sccm.

[0020] Preferably, during the hot wire vapor deposition, the operating power is controlled to be greater than 50W. DETAILED DESCRIPTION

[0021] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with some embodiments. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0022] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0023] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0024] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0025] In the present application, unless otherwise clearly specified and limited, a first feature being “above” or “below” a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being “above”, “above”, and “above” a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being “below”, “below”, and “below” a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0026] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be the only implementation method.

[0027] The method for forming a silicon thin film of the present invention is further described below in conjunction with an embodiment, but the present invention is not limited thereby. The method of the present invention is intended to provide an improved method for forming a silicon thin film, which forms a silicon thin film with hemispherical grains of good uniformity on a substrate, thereby improving the yield of the product, and the method is simple to prepare, easy to control, and suitable for large-scale production.

[0028] In one embodiment of the method for forming a silicon thin film of the present invention, the following steps are included:

[0029] providing a substrate;

[0030] Depositing a first silicon thin film on the substrate;

[0031] Performing oxidation treatment on the surface of the first silicon film to form a silicon oxide layer;

[0032] A second silicon thin film is grown on the silicon oxide layer, wherein the crystal grains of the first silicon thin film and the second silicon thin film are hemispherical.

[0033] The present invention first deposits a first silicon film on a substrate, for example, by hot wire vapor deposition (HWCVD). Specifically, HWCVD, also known as catalytic chemical vapor deposition, utilizes molecules to undergo a catalytic decomposition reaction on a heated metal wire, and deposits and polymerizes on the surface of the substrate to form a film. During the deposition process, HWCVD uses a high-carbon electrode, so the deposited silicon material is relatively carbon-rich, and the morphology of the film can be well controlled. Then, the surface of the first silicon film is oxidized to form a silicon oxide layer, and then a second silicon film is grown on the silicon oxide layer, for example, by HWCVD, so that the grains of the first silicon film and the second silicon film can be well controlled to be hemispherical. The grain uniformity of the first silicon film and the second silicon film is good, which improves the performance of the substrate and the yield rate. Moreover, the first silicon film and the second silicon film are regulated by the silicon oxide layer, which is more conducive to the performance of the substrate. The formation methods of the first silicon film and the second silicon film are similar, and only some parameters need to be changed. The preparation is simple and easy to control, and it is suitable for large-scale production.

[0034] Specifically, the substrate is a single crystal silicon substrate. On the substrate, a hot wire vapor deposition technology (HWCVD) with a wide temperature window is used to deposit the first silicon film. Specifically, SiH4 gas is used, the flow rate of SiH4 gas is 0.2-0.6sccm, and the working power is controlled to be 30-50W. Deposition is carried out in this condition atmosphere to grow the first silicon film, and the grains are hemispherical. During the deposition process, since HWCVD uses a high carbon electrode, the deposited silicon material is relatively carbon-rich, and the morphology of the film can be well controlled.

[0035] Next, the surface of the first silicon film is oxidized to form a silicon oxide layer with a thickness of about 10 nm. In the oxidation treatment, conventional wet oxidation methods, dry oxidation methods, etc. can be used to oxidize the surface of the first silicon film to form a silicon oxide layer. The thickness of the silicon oxide layer can be adjusted according to actual needs.

[0036] Next, a second silicon film is grown on the silicon oxide layer. Preferably, the second silicon film is deposited by using a hot wire vapor deposition technique (HWCVD) with a wide temperature window. Specifically, SiH4 gas and H2 gas are used, the flow rate of SiH4 gas is 0.2-0.6sccm, the flow rate of H2 gas is 0.6-0.8sccm, and the working power is controlled to be greater than 50W. Deposition is performed in this condition atmosphere to grow the second silicon film, and the grains are hemispherical.

[0037] Based on this, the present invention first deposits a first silicon film on a substrate, for example, by hot wire vapor deposition (HWCVD). During the deposition process, since HWCVD uses a high carbon electrode, the deposited silicon material is relatively carbon-rich, and the morphology of the film can be well controlled. Then, the surface of the first silicon film is oxidized to form a silicon oxide layer, and then the second silicon film is grown on the silicon oxide layer, for example, by HWCVD, so that the grains of the first silicon film and the second silicon film can be well controlled to be hemispherical. The first silicon film and the second silicon film have good grain uniformity, which improves the performance of the substrate and the yield rate. Moreover, the first silicon film and the second silicon film are regulated by the silicon oxide layer, which is more conducive to the performance of the substrate. The formation methods of the first silicon film and the second silicon film are similar, and only some parameters need to be changed. The preparation is simple and easy to control, and it is suitable for large-scale production.

[0038] The above disclosure is only a preferred embodiment of the present invention, which certainly cannot be used to limit the scope of rights of the present invention. Therefore, equivalent changes made according to the scope of the patent application of the present invention are still within the scope covered by the present invention.

Claims

1. A method for forming a silicon thin film, characterized in that: The following steps are involved: providing a substrate; Depositing a first silicon thin film on the substrate; Performing oxidation treatment on the surface of the first silicon film to form a silicon oxide layer; A second silicon thin film is grown on the silicon oxide layer, wherein the crystal grains of the first silicon thin film and the second silicon thin film are hemispherical.

2. The method for forming a silicon thin film according to claim 1, wherein: The substrate is a single crystal silicon substrate.

3. The method for forming a silicon thin film according to claim 1, wherein: Also includes: The first silicon thin film is formed by hot-wire vapor deposition.

4. The method for forming a silicon thin film according to claim 3, wherein: In the hot wire vapor deposition, SiH4 gas is used, and the flow rate of the SiH4 gas is 0.2-0.6 sccm.

5. The method for forming a silicon thin film according to claim 3, wherein: In the hot wire vapor deposition, the operating power is controlled to be 30-50W.

6. The method for forming a silicon thin film according to claim 1, wherein: The oxidation treatment includes wet oxidation and dry oxidation.

7. The method for forming a silicon thin film according to claim 1, wherein: The thickness of the silicon oxide layer is 10-20 nm.

8. The method for forming a silicon thin film according to claim 1, wherein: Also includes: The second silicon thin film is formed by hot wire vapor deposition.

9. The method for forming a silicon thin film according to claim 8, wherein: In the hot filament vapor deposition, SiH4 gas and H2 gas are used, the flow rate of the SiH4 gas is 0.2-0.6 sccm, and the flow rate of the H2 gas is 0.6-0.8 sccm.

10. The method for forming a silicon thin film according to claim 9, wherein: In the hot wire vapor deposition, the operating power is controlled to be greater than 50W.