JP2671359B2 - Method for manufacturing semiconductor device - Google Patents

Description

The present invention relates to a method for manufacturing a semiconductor device.

[Conventional technology]

Trench isolation method of forming a V-shaped groove and filling an insulating layer as one of element isolation methods of a semiconductor device
It has been known.

2 (a) and 2 (b) are cross-sectional views of a semiconductor chip shown in the order of steps for explaining a conventional method of manufacturing a semiconductor device.

As shown in FIG. 2A, a photoresist film 3 is formed on the silicon substrate 1 and patterned to form an opening 4 having a width of about 1 μm. Next, as shown in FIG. 2 (b),
The silicon substrate 1 is etched by using the photoresist film 3 as a mask by the anisotropic etching with KOH to form a V-shaped groove 7.

[Problems to be solved by the invention]

In the above-described conventional method for manufacturing a semiconductor device, since a solution such as KOH is used as an etching method, side etching from the photoresist pattern is unavoidable, so that the width is 1
There is a drawback that it is difficult to form a V-shaped groove of less than μm.

An object of the present invention is to provide a method for manufacturing a semiconductor device in which the degree of integration is improved by forming an element isolation layer having a width of less than 1 μm by a groove filling method.

[Means for solving the problem]

A method of manufacturing a semiconductor device according to the present invention comprises a step of forming a first insulating film on a semiconductor substrate, a step of selectively etching the first insulating film to provide an opening having a width of about 1 μm, Depositing a second insulating film on the surface including the opening to form a void in the opening; and etching back the entire surface of the second insulating film by anisotropic etching to form a void in the lower portion of the void. And a step of forming a V-shaped groove in the semiconductor substrate.

〔Example〕

 Next, the present invention will be described with reference to the drawings.

1 (a) to 1 (e) are sectional views of a semiconductor chip shown in the order of steps for explaining an embodiment of the present invention.

First, as shown in FIG. 1A, a silicon nitride film 2 is deposited on a silicon substrate 1 by, for example, a CVD method.
Next, a photoresist film 3 is applied on the silicon nitride film 2 and patterned, and then CF is used with the photoresist film 3 as a mask.
_The silicon nitride film 2 is etched by plasma etching using ₄ + H ₂ gas to form an opening 4 having a width of about 1 μm.

Next, as shown in FIG. 1B, the photoresist film 3
Are removed by using, for example, O ₂ plasma, and a silicon oxide film 5 is deposited on the surface including the opening 4 by the CVD method. At this time, the step coverage is deteriorated inside the opening 4, and a space (hereinafter referred to as a void) 6 is formed.

Next, as shown in FIG. 1C, the entire surface is ion milled to etch back the silicon oxide film 5. At this time, since there is a void 6 in the opening 4, the insulating film 5 under the void 6 is removed and the upper portion of the silicon substrate 1 is also sequentially etched to form a V-shaped groove 7 having a width of less than 1 μm. .

Next, as shown in FIG. 1D, the silicon oxide film 5 used for the mask is sequentially removed by, for example, hydrofluoric acid and the silicon nitride film 2 by, for example, hot phosphoric acid, and then BPSG is formed on the surface including the groove 7. The film 8 is deposited.

Next, as shown in FIG. 1 (e), the BPSG film 8 was etched back by CF ₄ + H ₂ plasma and buried in the groove 7.
The BPSG film 8 is left as a buried layer for element isolation.

Here, instead of the silicon nitride film 2, a silicon oxide film formed by a CVD method may be used.

〔The invention's effect〕

As described above, according to the present invention, an opening having a width of about 1 μm is provided in the first insulating film provided on the silicon substrate, and a void is generated in the second insulating film deposited in the opening. By providing a V-shaped groove in the silicon substrate by anisotropic etching utilizing the above, an element isolation layer having a width of less than 1 μm can be obtained, which has the effect of improving the integration degree of the semiconductor device.

[Brief description of the drawings]

1 (a) to 1 (e) are cross-sectional views of a semiconductor chip shown in the order of steps for explaining an embodiment of the present invention, and FIGS. 2 (a) and 2 (b) show a conventional method of manufacturing a semiconductor device. FIG. 4 is a cross-sectional view of a semiconductor chip shown in the order of steps for explaining the method. 1 ... Silicon substrate, 2 ... Silicon nitride film, 3 ... Photoresist film, 4 ... Opening part, 5 ... Silicon oxide film,
6 ... Void, 7 ... Groove, 8 ... BPSG film.

Claims (1)

(57) [Claims] 1. A method comprising: forming a first insulating film on a semiconductor substrate; selectively etching the first insulating film to form an opening having a width of about 1 μm; and including the opening. A step of depositing a second insulating film on the surface to generate a void in the opening; and a step of etching back the entire surface of the second insulating film by anisotropic etching and applying V to the semiconductor substrate below the void. And a step of forming a V-shaped groove.