JP2844641B2 - Silicon planarization method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a method for planarizing silicon in a manufacturing process of a semiconductor device.

[Conventional technology]

2. Description of the Related Art With the increase in the degree of integration of semiconductor integrated circuits, the steps for manufacturing semiconductor elements have become diversified. In particular, when manufacturing a semiconductor device using silicon as a semiconductor, irregularities may be formed on a silicon surface on which a semiconductor element is to be formed. When a semiconductor element is formed on silicon having unevenness, the characteristics of the semiconductor element deteriorate. FIG. 2 shows a state in which a semiconductor element is formed on a silicon surface having irregularities. In the figure, 11 is a semiconductor substrate, 12 is an interlayer insulating film, 13 is a single crystal silicon film, 14 is a gate insulating film, 15 is a gate electrode, 16
Is an n-type high concentration impurity diffusion layer.

[Problems to be solved by the invention]

When a semiconductor element is formed on silicon having unevenness, it is necessary to flatten the unevenness because the characteristic of the semiconductor element is deteriorated. A method of applying a molecular organic film or the like to flatten the surface and performing etching under the condition that the etching rate of the polymer organic film is equal to that of silicon to flatten silicon is considered. However, it is not practical under the condition that the etching rate of the polymer organic film is equal to the etching rate of silicon, because the surface of silicon is roughened separately from the unevenness of the silicon surface.

An object of the present invention is to provide a method for planarizing silicon which has solved the above-mentioned problems.

[Means for solving the problem]

In order to achieve the above object, in the method of planarizing silicon according to the present invention, a silicon oxide film is formed on an uneven silicon surface, and the surface is planarized using a high-molecular organic material. After the etching is performed under the condition that the etching rates of the organic film and the silicon oxide film are equal and the surface of the silicon oxide film is flattened, the etching is performed under the condition that the etching rates of the silicon oxide film and the silicon are equal and the silicon surface is flattened. It becomes something.

〔Example〕

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic sectional view showing the structure of a semiconductor device manufactured by using the silicon planarization method of the present invention.

In the figure, an interlayer insulating film 2 and a single crystal silicon film 3 for forming a semiconductor element are sequentially provided on a silicon substrate 1, and a gate insulating film 4 and a gate electrode 5 are formed on the single crystal silicon film 3. Hereinafter, a manufacturing method of the illustrated semiconductor device will be described.

3 (a) and 3 (b) are schematic views sequentially showing a method for planarizing silicon of the present invention. 3 (a), an interlayer insulating film 22 made of a silicon oxide film is formed on a silicon substrate 21, a polycrystalline silicon layer is formed by a CVD method, and a polysilicon layer is formed by a zone melt method. The single crystal silicon film 23 is formed by performing single crystallization. At this time, irregularities occur on the silicon surface due to single crystallization of polysilicon. Next, after forming a silicon oxide film 24 having a thickness equal to or greater than the roughness of the silicon surface on the single-crystal silicon film 23 by a CVD method, a polymer organic film 25 is formed by a spin coating method, and the surface is reflow-baked. Perform planarization. Subsequently, etching is performed up to the arrow 26 by using uniform etching of the polymer organic film and the silicon oxide film. Next, when the silicon oxide film of the interlayer insulating film 22 and the single crystal silicon film 23 are etched at a constant speed up to the arrow 27, the single crystal silicon film 23 is planarized, and the structure of FIG. 3B is obtained. Can be FIG. 1 shows a structure in which a gate insulating film 4 is formed on this single crystal silicon film, a gate electrode 5 is patterned, and then an n-type high-concentration impurity diffusion layer 6 is formed by ion implantation.

As described above, in the example, the unevenness generated when the polycrystalline silicon was single-crystallized by using the zone melt method was flattened, but if the unevenness of the silicon generated during the semiconductor element manufacturing process was flattened, The present invention is not limited to the irregularities generated during the single crystallization of polycrystalline silicon.

〔The invention's effect〕

As described above, according to the present invention, a semiconductor element can be formed on a flat silicon surface, and there is an effect that reliability can be improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a semiconductor device manufactured using the present invention,
FIG. 2 is a schematic diagram showing a conventional example, and FIGS. 3 (a) and 3 (b) are schematic diagrams for explaining a manufacturing process of the present invention. 1,21 ... Silicon substrate, 2,22 ... Interlayer insulation film 3,23 ... Single crystal silicon film, 4 ... Gate insulation film 24 ... Silicon oxide film, 5 ... Gate electrode 25 ... Polymer organic Film 6: n-type high-concentration impurity diffusion layer 26: constant-speed etching end point of polymer organic material and silicon oxide film (arrow) 27: constant-speed etching end point of silicon oxide film and single crystal silicon (arrow)

Claims (1)

(57) [Claims] 1. A method in which a silicon oxide film is formed on an uneven silicon surface, the surface is flattened using a polymer organic material, and then the etching rates of the polymer organic film and the silicon oxide film are equal. A flattening method for a silicon oxide film, wherein the surface of the silicon oxide film is flattened, and then the silicon oxide film is etched under the same etching rate as that of silicon to flatten the silicon surface.