JPH036815A - Manufacture of semiconductor device and semiconductor device - Google Patents

Abstract

PURPOSE:To form a pattern without damage by patterning an insulating film containing impurity formed on a semiconductor film, and then heat-treating it in an oxidative atmosphere. CONSTITUTION:A polycrystalline silicon film 2 is deposited on a silicon substrate 1 by a CVD method, and a silicon dioxide of an insulating film 3 containing impurity, boron, etc., is deposited on the film 2 by a CVD method. The film 3 is patterned by a normal photolithography and etching. It is heat-treated in an atmosphere having oxidative properties. As a result, only the film 2 under the film 3 is completely varied to silicon dioxide 4, the film 2 of a region having no film 3 is altered only at the surface layer to silicon dioxide 4, and the film 2 remain thereunder without oxidation. Accordingly, a semiconductor film having a pattern inverted from the pattern of the insulating film an be formed without damage.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for manufacturing a semiconductor device and a semiconductor device.

BACKGROUND OF THE INVENTION FIG. 3 is a process diagram showing a conventional method of patterning a polycrystalline silicon film. As shown in FIG. 3(a), a resist pattern 22 is formed on a polycrystalline silicon film 21 formed on a silicon substrate 20 having steps. After that, the resist pattern 22 is used as a mask.
The polycrystalline silicon film 21 having the same pattern as the resist pattern 22 is formed by etching and removing the polycrystalline silicon 1llj21 in the area where the resist pattern 22 does not exist.

At this time, instead of wet etching, which is difficult to form fine patterns, dry etching is used, which can form fine patterns (Figure 3 (b)).
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Problems to be Solved by the Invention However, according to the conventional pattern forming method using dry etching, the underlying layer of the film to be etched is damaged by the bombardment of ions and electrons constituting the plasma, resulting in crystal defects 23 occurs. Further, when anisotropic etching is performed to form a fine pattern, there is a problem in that etching residue 24 is generated on the side wall portion of the step.

The present invention has been attempted in view of the above-mentioned problems, and an object of the present invention is to provide a method for manufacturing a semiconductor device and a semiconductor device that allow pattern formation without causing damage.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides a step of forming a semiconductor film on a semiconductor substrate, then forming an insulating film containing impurities on the semiconductor film, and converting the insulating film into butter. After the coating, all of the semiconductor film under the insulating film is converted into a first oxide film by heat treatment in an oxidizing atmosphere, and only the surface layer of the semiconductor film in the area where there is no insulating film is converted into a second oxide film. It is equipped with a process of.

Effect of the present invention With the above-described structure, impurities are diffused from the insulating film into the semiconductor film under the insulating film containing impurities, and oxidizing species are easily diffused into the insulating film. The film has a higher oxidation rate than the semiconductor film below the region without the insulating film. Therefore, while the entire semiconductor film under the insulating film is oxidized, only the surface layer of the semiconductor film in areas without the insulating film is oxidized, resulting in a pattern that reverses the pattern of the insulating film without causing damage. It becomes possible to form a semiconductor film having the following properties.

Example (Example 1) FIG. 1 is a process diagram showing a method for forming a pattern of a polycrystalline silicon film in a first example of the present invention. Below, the first
A method of patterning a polycrystalline silicon film according to the present invention will be explained with reference to the drawings.

As shown in FIG. 1(a), CVD is applied onto a silicon substrate 1.
A polycrystalline silicon film 2 is deposited by a method, and silicon dioxide, which is an insulating film 3 containing impurities such as boron, arsenic, phosphorus, etc., is further deposited on the polycrystalline silicon film 2 by a CVD method. Next, the impurity-containing insulating film 3 is patterned using conventional photolithography and etching (FIG. 1(b)). Next, heat treatment is performed in an oxidizing atmosphere, for example, an oxygen gas atmosphere. Heat treatment is performed using an electric furnace.
00~l! It is carried out for several minutes to several hours at a temperature of 00°C. As a result, as shown in FIG. 1(C), only the polycrystalline silicon film 2 under the insulating film 3 containing impurities is completely changed to silicon dioxide 4, and the polycrystalline silicon film 2 in the area without the insulating film 3
Only the surface layer changes to silicon dioxide 4, and the polycrystalline silicon film 2 remains without being oxidized underneath.

As described above, a semiconductor film having a pattern that is an inversion of the pattern of an insulating film can be formed without causing damage.

(Example 2) FIG. 2 is a process cross-sectional view of a MOS transistor in a second example of the present invention. Hereinafter, a method for manufacturing a MOS transistor according to the present invention will be explained using FIG.

As shown in FIG. 2(a), a MOS transistor having an impurity region f2 forming a source-drain region and a gate electrode I3 in a region separated by an isolation oxide film 11 is formed on a silicon substrate 10 using a conventional method. form.

Further, an oxide film I4 is formed on the upper side of the gate electrode 13. Next, as shown in FIG. 2(b), the source/drain I
Polycrystalline silicon 15 is deposited so as to be in contact with 2. Next, an insulating film IB containing impurities is deposited and patterned (FIG. 2(C)). This patterning also serves to form a contact hole 17 on the source/drain 12 to connect to the wiring.

Next, as described in Example 1, by performing heat treatment in an oxidizing atmosphere, as a result, the insulating film 1 containing impurities
Only the polycrystalline silicon film 15 under B completely changes to silicon dioxide 18, and only the surface layer of the polycrystalline silicon film 15 in the area where there is no insulating film 16 changes to silicon dioxide 18, and the area below it is not oxidized. However, the polycrystalline silicon film 15 remains. If the insulator 1B is silicon dioxide containing 5 to 8% each of boron and phosphorus as impurities, it will flow at a heat treatment temperature of 850° C. or higher, resulting in a shape as shown in FIG. 2(d). Next, as shown in FIG. 2(e), the silicon dioxide 18 formed on the surface of the polycrystalline silicon 15 in contact with the source/drain 12 is removed by a wet etching process using a hydrofluoric acid solution. Subsequently, wiring 19 is formed (FIG. 2(f)).

As described above, in the semiconductor device of the present invention, polycrystalline silicon in contact with the source/drain can be formed without deteriorating the properties of the underlying silicon surface, and the contact hole connecting the wiring and the source/drain can be patterned. Patterning of polycrystalline silicon can be formed in a self-aligned manner by a single photo process. In addition, insulating films containing impurities can be used as they are for wiring and transistor insulating films, and in particular,
If the insulating film is made of silicon dioxide containing a few percent of boron and phosphorus, it will be flattened during the oxidation process of polycrystalline silicon, resulting in a structure that is less prone to disconnections. Furthermore, the contact area between the wiring and the source/drain is increased by the polycrystalline silicon film, resulting in a contact structure with low resistance.

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, by buttering an insulator containing impurities, it is possible to control the oxidation rate of a polycrystalline silicon film and form a pattern of the polycrystalline silicon film. In the case of a single-crystal silicon substrate, its surface shape and crystallinity do not deteriorate, and its practical effects are great.

[Brief explanation of the drawing]

FIG. 1 is a process diagram showing a method of patterning a polycrystalline silicon film in a first embodiment of the present invention, FIG. 2 is a process cross-sectional view of a MOS transistor in a second embodiment of the present invention, and FIG. FIG. 3 is a process diagram showing a conventional method for forming a pattern of a polycrystalline silicon film. 1.10...Silicon substrate, 2,15...Polycrystalline silicon film, 3,1lli...Insulating film containing impurities, 4
．． 18...Silicon dioxide film.

Claims (2)

[Claims] (1) After forming a semiconductor film on a semiconductor substrate, forming an insulating film containing impurities on the semiconductor film, and after patterning the insulating film, heat treatment is performed in an oxidizing atmosphere so that the area under the insulating film is A method for manufacturing a semiconductor device, comprising the steps of converting all of the semiconductor film into a first oxide film, and converting only the surface layer of the semiconductor film in a region where the insulating film is not present into a second oxide film. (2) between a MOS transistor formed on a semiconductor substrate, an isolation region that electrically isolates the MOS transistors from each other, and a wiring that connects an impurity region that forms the source or drain of the MOS transistor; A gate of a MOS transistor and a semiconductor film pattern extending above the isolation region, wherein an end of an insulating film containing impurities in a region other than the semiconductor film pattern and an end of the semiconductor film pattern are formed in a self-aligned manner. A semiconductor device characterized by: