JP3003804B2 - Method for manufacturing semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device effective for forming a contact hole in a self-aligned contact.

[0002]

2. Description of the Related Art A conventional method for manufacturing a semiconductor device will be described below. FIG. 2 is a process sectional view of a conventional semiconductor device manufacturing method. First, as shown in FIG. 2A, a polysilicon gate 2 is formed on a silicon substrate 1 via a silicon oxide film 1a, and a silicon nitride film 3 is
0 ° is formed. A polysilicon film 4, a silicon nitride film 5, and a polysilicon film 6 are formed thereon.

Further, after forming a photoresist pattern and etching the silicon oxide film 7 containing boron (B) and phosphorus (P) by reactive ion etching (RIE), the photoresist is removed and the polysilicon film 6 contains chlorine. Dry etching using an etching gas to be performed. Next, as shown in FIG. 2 (b), a silicon oxide film 10 was deposited by thermal decomposition of alkoxysilane (TEOS) by a reduced pressure CVD method at about 1000 °. Then Figure 2
As shown in (c), the entire surface of the silicon oxide film 10 is etched. At this time, the underlying nitride film 3 is also etched off at the same time, exposing the silicon substrate 1. This leaves the silicon oxide film 10a on the side wall of the hole.

[0004]

However, in the above-mentioned conventional method for manufacturing a semiconductor device, the silicon oxide film 10 must be over-etched to expose the silicon substrate 1 as shown in FIG. . Therefore, there is a problem that a crown-shaped protrusion is formed on the upper surface of the contact as shown in FIG.
The protrusion is caused by a difference in dry etching rate between the silicon oxide film 10 and the silicon oxide film 7 including B and P under the silicon oxide film 10.

An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide a method of manufacturing a semiconductor device capable of improving the dielectric strength of a contact portion.

[0006]

In order to achieve this object, a method of manufacturing a semiconductor device according to the present invention comprises forming a contact hole in a silicon oxide film containing B and P,
An oxide film containing P is deposited by a method, and heat treatment is performed in an oxygen atmosphere at 800 ° C. or higher.

[0007]

With this configuration, the silicon oxide film containing P deposited by the normal pressure CVD method has a dry etching rate substantially equal to that of the silicon oxide film containing B and P which are the bases. It became possible to prevent. Further, by performing the heat treatment, the dielectric strength at the contact portion of the polysilicon film can be improved more than the conventional method.

[0008]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a process sectional view of a method of manufacturing a semiconductor device according to an embodiment of the present invention. First, as shown in FIG. 1A, a polysilicon gate 2 is formed on a silicon substrate 1 via a silicon oxide film 1a, and a silicon nitride film 3 is formed thereon by about 400.degree. A polysilicon film 4, a silicon nitride film 5, and a polysilicon film 6 are formed thereon. Further, after forming a photoresist pattern and etching the silicon oxide film 7 containing B and P by RIE, the photoresist is removed, and the polysilicon layer 6 is dry-etched using an etching gas containing chlorine. Then, as shown in FIG. 1B, a silicon oxide film 8 containing P is deposited by normal pressure CVD. afterwards,
A heat treatment is performed at 900 ° C. in an oxygen atmosphere for 30 minutes.
Next, as shown in FIG. 1C, the silicon oxide film 8 is etched to leave the silicon oxide film 8a on the side wall of the hole. At this time, the underlying nitride film 3 is simultaneously etched to expose the silicon substrate 1. 1 (b) and 1 (c).
9 is a polysilicon oxide film.

[0010]

As described above, according to the present invention, a P-containing silicon oxide film is formed by a normal pressure CVD method,
By performing the heat treatment in an oxidizing atmosphere at a temperature of 00 ° C. or higher, it is possible to prevent the occurrence of a crown-shaped protrusion on the upper surface of the contact, and to further improve the withstand voltage in the contact portion of the polysilicon film. An excellent method of manufacturing a semiconductor device can be realized.

[Brief description of the drawings]

FIG. 1 is a process sectional view of a method for manufacturing a semiconductor device according to an embodiment of the present invention.

FIG. 2 is a process sectional view of a conventional semiconductor device manufacturing method.

[Explanation of symbols]

 Reference Signs List 1 silicon substrate (semiconductor substrate) 5 silicon nitride film 6 polysilicon film 7 silicon oxide film 8 silicon oxide film

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21/3205 H01L 21/321 H01L 21/3213 H01L 21/768 H01L 21/3065 H01L 27/108

Claims (1)

(57) [Claims] A step of forming a photoresist pattern on a silicon oxide film containing boron and phosphorus formed on a semiconductor substrate and anisotropically etching the silicon oxide film using the photoresist pattern as a mask; After the photoresist pattern is removed, a polysilicon film formed under the silicon oxide film is selectively etched with respect to a silicon nitride film as an underlayer, and phosphorus is contained by a normal pressure chemical vapor deposition method. A method for manufacturing a semiconductor device, comprising: a step of depositing a silicon oxide film; a step of performing heat treatment at 800 ° C. or higher in an oxygen atmosphere; and a step of selectively etching the silicon nitride film with respect to the semiconductor substrate.