JPH07147232A - Manufacture of semiconductor thin film - Google Patents

Abstract

PURPOSE:To form a semiconductor thin film whose impurity concentration is low on an insulating film, and manufacture a semiconductor device having an active region whose characteristics can be controlled. CONSTITUTION:In the manufacturing method of a semiconductor thin film wherein, after an insulating film 2 is formed on a single crystal silicon substrate, and a seed region 3 where a part of the single crystal silicon substrate 1 surface is exposed by partially eliminating the insulating film 2 is formed, a semiconductor thin film is formed on the seed region 3 and the insulating film 2, a process wherein a silicon film containing boron is formed on the surface of the single crystal silicon substrate 1 which is the seed region 3 and the insulating film 2, and a process wherein a semiconductor thin film having desired thickness is formed by repeating a plurality of times the process wherein a silicon oxide film is formed by heat-treating the silicon film, and the process wherein the silicon oxide film is eliminated are contained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor thin film in which a single crystal silicon film is formed on an insulating film.

[0002]

2. Description of the Related Art Conventionally, as a method for forming a single crystal silicon film on an insulating film such as a silicon oxide film, a lateral solid phase growth method (such as that disclosed in Japanese Patent Laid-Open No. 64-39378) ( L-SPE: Lateral Soli
d Phase Epitaxy).

Generally, a single crystal silicon substrate is thermally oxidized to form an insulating film made of a silicon oxide film, a part of the silicon oxide film is removed, and a seed region, which is a region where the surface of the single crystal silicon substrate is exposed, is formed. After etching with a gas containing chlorine, an amorphous silicon film is formed by thermal CVD in the same reaction tube.

After that, a heat treatment for crystallization is performed for about 10 hours in a nitrogen atmosphere maintained under a temperature condition near the formation temperature of the amorphous silicon film to obtain a crystallized silicon layer.

However, in the above-mentioned conventional method, when the plane orientation (100) is used as the single crystal silicon substrate, the crystallization of silicon occurs according to the substrate orientation in the vertical direction, but the crystal growth of silicon shifts in the horizontal direction. At that time, the plane orientation (11
1) will be mixed.

For this reason, there is a drawback that crystal growth does not proceed in a fixed plane orientation, random nucleation occurs, and the lateral solid phase growth distance cannot be extended.

Therefore, even in the prior art, after the amorphous silicon film is formed in order to obtain the solid phase growth distance in the lateral direction, silicon ions are implanted or impurities such as phosphorus and boron are introduced, and then the silicon crystal is formed. Attempts have been made to perform a heat treatment for chemical conversion.

The former is effective in cutting excess silicon ions into the amorphous silicon film, breaking the silicon-silicon bond, and suppressing random nucleation by heat treatment for crystallization.

The latter is, for example, Japanese Patent Publication No. 59-474.
As described in Japanese Patent Laid-Open No. 53-53, it is known that impurities such as phosphorus enter the amorphous silicon film to be crystallized, which has an effect of suppressing nucleation by heat treatment for crystallization. There is.

Furthermore, there is also a method of forming a silicon film containing impurities by introducing a gas containing impurities at the time of forming the amorphous silicon film.

[0011]

However, in the case of the above-mentioned conventional method, although the distance for solid phase growth from the seed region to the insulating film becomes long, the obtained crystallized silicon layer is used as an active layer which becomes a channel of a transistor. When a semiconductor device is formed as described above, the impurity concentration of the active layer is determined when the recrystallized silicon layer is formed. Therefore, there is a problem in that the characteristics such as the specific resistance of the semiconductor device cannot be controlled.

An object of the present invention is to solve the above problems and form a crystallized silicon layer having a low impurity concentration on an insulating film,
An object of the present invention is to provide a method for manufacturing a semiconductor thin film, which can obtain a semiconductor device whose characteristics can be controlled.

[0013]

To achieve the above object, the present invention employs the method described below.

According to the present invention, an insulating film is formed on a single crystal silicon substrate, and the insulating film is partially removed to form a seed region exposing a part of the surface of the single crystal silicon substrate. After that, in the method of manufacturing a semiconductor thin film for forming a semiconductor thin film on the seed region and the insulating film, a step of forming a silicon film containing boron on the single crystal silicon substrate surface which is the seed region and the insulating film, This process includes the steps of heat-treating the silicon film to form a silicon oxide film and removing the silicon oxide film a plurality of times to form a semiconductor thin film having a desired thickness.

According to a second aspect of the present invention, an insulating film is formed on a single crystal silicon substrate, and the insulating film is partially removed to form a seed region exposing a part of the surface of the single crystal silicon substrate. After that, in the method of manufacturing a semiconductor thin film for forming a semiconductor thin film on the seed region and the insulating film, a step of forming a silicon film containing boron on the single crystal silicon substrate surface which is the seed region and the insulating film, The method includes a step of forming a silicon-based refractory metal compound on the silicon film and heat-treating it, and a step of removing the heat-treated silicon-based refractory metal compound and forming a semiconductor thin film having a desired thickness.

[0016]

According to the method of manufacturing a semiconductor thin film of claim 1, after forming a silicon film containing boron, the silicon film is heat treated to form a silicon oxide film and remove the silicon oxide film. Since a semiconductor thin film having a desired thickness is repeatedly formed a plurality of times, it is possible to reduce the boron concentration in the semiconductor thin film and manufacture a semiconductor device having an active layer region in which characteristics such as resistivity can be controlled. it can.

According to the method of manufacturing a semiconductor thin film of the second aspect, after a silicon film containing boron is formed, a silicon-based refractory metal compound is formed on the silicon film, heat-treated, and further heat-treated. Since a metal compound is removed to form a semiconductor thin film having a desired thickness, a boron concentration in the semiconductor thin film can be reduced, and a semiconductor device having an active layer region in which characteristics such as resistivity can be controlled is manufactured. be able to.

[0018]

EXAMPLE An example of a method for manufacturing a semiconductor thin film according to the present invention will be specifically described below with reference to the sectional views of FIGS.

First, as shown in FIG.
0) P-type single crystal silicon substrate 1 is prepared, and a temperature of 1100 is set on the single crystal silicon substrate 1 (on one surface).
A silicon oxide film having a film thickness of about 150 nm is formed as the insulating film 2 in an atmosphere of oxygen / nitrogen partial pressure at 0 ° C. The single crystal silicon substrate 1 may be of N type. Further, although the silicon oxide film is formed as the insulating film 2, other than this, the silicon nitride, a two-layer film of a silicon oxide film and a silicon nitride, or the like may be used as the insulating film 2.

Next, after patterning a resist (not shown) using the photolithography technique, the insulating film 2 is formed as shown in FIG.
Are partially removed with an aqueous solution of hydrofluoric acid to expose the surface of the single crystal silicon substrate 1 to form a seed region 3.

Then, the etching chamber as a pretreatment chamber was evacuated to a pressure of about 1 × 10 ^-6 Torr with a multi-chamber type DC sputtering apparatus, and then argon gas was introduced as shown in FIG. A high frequency power of 1 KW is applied at a pressure of 5 × 10 ⁻³ Torr to etch the surface of the single crystal silicon substrate 1.

By this etching process, the silicon film 4 containing boron, which will be described later, after cleaning the single crystal silicon substrate 1.
Even if a natural oxide film is formed on the seed region 3 before the formation, this natural oxide film can be easily removed.

Then, the sample is moved to the film forming chamber of the same multi-chamber type DC sputtering apparatus, and as shown in FIG.
A boron-doped silicon target having a concentration of 0 ¹⁹ cm ⁻³ is sputtered to form a silicon film 4 containing boron and having a thickness of 500 nm.

After that, heat treatment is performed for 12 hours at a temperature of 570 ° C. in a nitrogen atmosphere with a flow rate of 2000 cc / min.

By carrying out this heat treatment, the silicon film 4 containing boron is first grown vertically into a single crystal according to the plane orientation (100) of the single crystal silicon substrate 1, and then the insulating film 2 is covered. Crystallized in the horizontal direction,
A crystallized silicon layer 6 having a film thickness of 500 nm shown in is obtained.

Further, since the silicon film 4 contains boron as an impurity, compared with the case where no impurity is introduced,
The solid phase growth distance in the lateral direction is also increased by 1 to 2 μm.

Further, as shown in FIG. 5, the crystallized silicon layer 6 is thermally oxidized at a temperature of 1000 ° C. in an oxygen atmosphere to form a silicon oxide film 5 having a film thickness of 200 nm on the surface thereof.

After that, as shown in FIG. 6, the silicon oxide film 5 is removed using a hydrofluoric acid-based aqueous solution.

As a result, the crystallized silicon layer 6 having a film thickness of 500 nm is thinned to a film thickness of 400 nm, and boron, which is an impurity in the silicon film 4, is also diffused outward during the oxidization process, resulting in an impurity concentration. Is reduced by about one digit.

The above-described steps of forming the silicon oxide film 5 and removing the silicon oxide film 5 are repeated four times,
As shown in FIG. 7, the thickness of the crystallized silicon layer 6 is finally reduced to 100 nm.

As a result, the boron concentration in the crystallized silicon layer 6 can be reduced to the order of 10 ¹⁴ cm ^-3 .

As described above, according to the method of this embodiment, the thickness of the silicon film 4 containing boron, the number of times the silicon oxide film 5 is formed and the silicon oxide film 5 is removed repeatedly, and the oxidation time are arbitrarily selected. As a result, the crystallized silicon layer 6
And the impurity concentration in the film of the crystallized silicon layer 6 can be controlled, and a semiconductor device having an active layer region whose characteristics such as specific resistance can be controlled can be manufactured.

In place of the oxidation treatment, a tungsten silicide film (WSi) which is a silicon-based refractory metal compound is used.
Film) by means of a DC sputtering device
It may be formed on top.

In this method of forming a silicon-based refractory metal compound, RTA (R
Heat treatment is performed in an atmosphere of nitrogen using an rapid thermal anneal device under the conditions of a temperature of 1000 ° C. and a treatment time of 1 minute.

By this momentary heat treatment, boron in the silicon film 4 is sucked up by the tungsten silicide film in the vicinity of the interface between the silicon film 4 containing boron and the tungsten silicide film. Then, if the tungsten silicide film is removed, the boron concentration can be reduced as in the case where the formation and removal of the silicon oxide film 5 are repeated. You may repeat this process as needed.

[0036]

As described above, according to the present invention, a silicon film containing boron is heat-treated in a nitrogen atmosphere to form a crystallized silicon layer and then a silicon oxide film is formed. Is repeatedly performed several times.

As a result, it is possible to provide a method for manufacturing a semiconductor thin film, which can reduce the boron concentration in the crystallized silicon layer and can manufacture a semiconductor device having an active layer region in which characteristics such as specific resistance can be controlled.

Further, according to the present invention, a silicon film containing boron is heat-treated in a nitrogen atmosphere to form a crystallized silicon layer, a silicon-based refractory metal compound is formed, and the silicon-based refractory metal is heat-treated. The metal compound is removed.

As a result, it is possible to provide a method for producing a semiconductor thin film which can reduce the boron concentration in the crystallized silicon layer and can produce a semiconductor device having an active layer region in which characteristics such as resistivity can be controlled.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a manufacturing process of an embodiment method of the present invention.

FIG. 2 is a cross-sectional view showing a manufacturing process of an embodiment method of the present invention.

FIG. 3 is a cross-sectional view showing a manufacturing process of an embodiment method of the present invention.

FIG. 4 is a cross-sectional view showing a manufacturing process of an embodiment method of the present invention.

FIG. 5 is a cross-sectional view showing a manufacturing process of an embodiment method of the present invention.

FIG. 6 is a cross-sectional view showing a manufacturing process of a method according to an embodiment of the present invention.

FIG. 7 is a cross-sectional view showing a manufacturing process of a method according to an embodiment of the present invention.

[Explanation of symbols]

 1 Single Crystal Silicon Substrate 2 Insulation Film 3 Seed Region 4 Silicon Film 5 Silicon Oxide Film 6 Crystallized Silicon Layer

Front page continuation (72) Inventor Kenichi Ishii 1-4 Umezono, Tsukuba City, Ibaraki Prefectural Institute of Industrial Technology Electronic Technology Research Institute (72) Inventor Katsuyoshi Aihara 840, Takeno, Shimotomi, Tokorozawa, Saitama Prefecture Chizen Watch Co., Ltd. Technical Research Center

Claims (2)

[Claims] 1. An insulating film is formed on a single crystal silicon substrate, and the insulating film is partially removed to form a seed region exposing a part of the surface of the single crystal silicon substrate. In the method of manufacturing a semiconductor thin film, which comprises forming a semiconductor thin film on the insulating film, a step of forming a silicon film containing boron on the surface of the single crystal silicon substrate, which is the seed region, and the insulating film; and heat treating the silicon film. And a step of forming a silicon oxide film and a step of removing the silicon oxide film are repeated a plurality of times to form a semiconductor thin film having a desired thickness. 2. An insulating film is formed on a single crystal silicon substrate, and the insulating film is partially removed to form a seed region exposing a part of the surface of the single crystal silicon substrate. In a method of manufacturing a semiconductor thin film for forming a semiconductor thin film on the insulating film, a step of forming a silicon film containing boron on the surface of the single crystal silicon substrate which is the seed region and the insulating film, and a silicon film on the silicon film. A method for producing a semiconductor thin film, comprising: a step of forming a heat-resistant high melting point metal compound and heat treatment; and a step of removing the heat-treated silicon-based high melting point metal compound to form a semiconductor thin film having a desired thickness.