JP3261444B2 - Manufacturing method of semiconductor thin film - 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 for manufacturing a semiconductor thin film for forming a single crystal silicon film on an insulating film.

[0002]

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

In general, 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 in which 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 in the same reaction tube by a thermal CVD method.

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

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

For this reason, there is a defect that crystal growth does not proceed in a predetermined plane orientation, nucleation occurs at random, and the solid phase growth distance in the horizontal direction does not increase.

Therefore, conventionally, after an amorphous silicon film is formed in order to obtain a solid phase growth distance in the lateral direction, silicon ions are implanted, or impurities such as phosphorus and boron are introduced. Attempts have been made to carry out a heat treatment for the formation of a layer.

The former has the effect of cutting off the silicon-silicon bond due to excessive silicon ions entering the amorphous silicon film and suppressing random nucleation due to heat treatment for crystallization.

The latter is disclosed, for example, in JP-B-59-474.
As described in Japanese Patent Application Publication No. 53-53, it is known that impurities such as phosphorus enter an amorphous silicon film to be crystallized, and have an effect of suppressing nucleation by a heat treatment for crystallization. I have.

Further, there is 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-described conventional method, although the distance of the solid phase growth from the seed region on the insulating film becomes longer, the obtained crystallized silicon layer is used as an active layer serving as a channel of a transistor. When a semiconductor device is formed as follows, the impurity concentration of the active layer is determined when the recrystallized silicon layer is formed. Therefore, there is a problem that characteristics such as 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,
It is an object of the present invention to provide a method of manufacturing a semiconductor thin film capable of obtaining a semiconductor device whose characteristics can be controlled.

[0013]

In order to achieve the above object, the present invention employs the following method.

According to the first 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. Thereafter, in the method for manufacturing a semiconductor thin film that forms a semiconductor thin film on the seed region and the insulating film, a step of forming a silicon film containing boron on the surface of the single-crystal silicon substrate that is the seed region and the insulating film; The method includes a step of forming a silicon oxide film by heat-treating the silicon film and a step of 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. Thereafter, in the method for manufacturing a semiconductor thin film that forms a semiconductor thin film on the seed region and the insulating film, a step of forming a silicon film containing boron on the surface of the single-crystal silicon substrate that 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 performing a heat treatment, and a step of removing the heat-treated silicon-based refractory metal compound to form a semiconductor thin film having a desired thickness.

[0016]

According to the method of manufacturing a semiconductor thin film according to the first aspect, after forming a silicon film containing boron, the silicon film is heat-treated to form a silicon oxide film and to 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 specific resistance can be controlled. it can.

According to the method of manufacturing a semiconductor thin film according to the second aspect, after forming a silicon film containing boron, a silicon-based high melting point metal compound is formed on the silicon film, heat-treated, and further heat-treated. Since a semiconductor thin film having a desired thickness is formed by removing a metal compound, 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 specific resistance can be controlled is manufactured. be able to.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment 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), a P-type single-crystal silicon substrate 1 is prepared, and a temperature of 1100 is formed 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 oxygen / nitrogen partial pressure atmosphere at a temperature of ° C. Incidentally, as the single crystal silicon substrate 1, an N-type can also be used. In addition, although the silicon oxide film is formed as the insulating film 2, the insulating film 2 may be a silicon nitride, a two-layer film of a silicon oxide film and a silicon nitride, or the like.

Next, after a resist (not shown) is patterned by using a photomechanical technique, as shown in FIG.
Is partially removed with a hydrofluoric acid aqueous solution to expose the surface of the single crystal silicon substrate 1 to form a seed region 3.

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

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

Next, the sample was moved to a 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 with a thickness of 500 nm.

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

By performing this heat treatment, the silicon film 4 containing boron first grows into a single crystal in the vertical direction according to the plane orientation (100) of the single crystal silicon substrate 1, and then the insulating film 2 is covered with the silicon film 4. Crystallization in the horizontal direction
As a result, a crystallized silicon layer 6 having a thickness of 500 nm is obtained.

Further, since the silicon film 4 contains boron as an impurity, the silicon film 4 has a larger thickness than when no impurity is introduced.
The solid phase growth distance in the lateral direction also increases by 1 to 2 μm.

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

Thereafter, 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 thickness of 500 nm is thinned to a thickness of 400 nm, and boron, which is an impurity in the silicon film 4, is also diffused outward during the oxidation process, so that the impurity concentration is reduced. Is reduced by about one digit.

The steps of forming the silicon oxide film 5 and removing the silicon oxide film 5 as described above 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 the present embodiment, the thickness of the silicon film 4 containing boron, the number of repetitions of the formation of the silicon oxide film 5 and the removal of the silicon oxide film 5, and the oxidation time are arbitrarily selected. As a result, the crystallized silicon layer 6
And the impurity concentration in the crystallized silicon layer 6 can be controlled, and a semiconductor device having an active layer region in which characteristics such as specific resistance can be controlled can be manufactured.

In place of the oxidation treatment, a tungsten silicide film (WSi
Film) by a DC sputtering apparatus.
It may be formed on top.

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

By this instant heat treatment, boron in the silicon film 4 is absorbed by the tungsten silicide film near the interface between the silicon film 4 containing boron and the tungsten silicide film. Thereafter, 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. This step may be repeated as necessary.

[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 repeated several times.

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

Further, according to the present invention, after a silicon film containing boron is heat-treated in a nitrogen atmosphere to form a crystallized silicon layer, a silicon-based high melting point metal compound is formed, and after the heat treatment, a silicon-based high melting point metal compound is formed. Metal compounds have been removed.

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

[Brief description of the drawings]

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

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

FIG. 3 is a sectional view showing a manufacturing process of the method according to the embodiment of the present invention.

FIG. 4 is a sectional view showing a manufacturing process of the method according to the embodiment of the present invention.

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

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

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

[Explanation of symbols]

 Reference Signs List 1 single-crystal silicon substrate 2 insulating film 3 seed region 4 silicon film 5 silicon oxide film 6 crystallized silicon layer

──────────────────────────────────────────────────続 き Continuing on the front page (72) Katsuyoshi Aihara, Inventor Takeshi Haseyama, Technical Research Institute, Citizen Watch Co., Ltd. 840, Shimotomi, Tokorozawa, Saitama Prefecture , A) JP-A-6-236894 (JP, A) JP-A-4-196311 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/20

Claims (2)

(57) [Claims] 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 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 serving as the seed region and the insulating film; Forming a silicon oxide film and removing the silicon oxide film 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 the 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 as the seed region and the insulating film; A method of manufacturing a semiconductor thin film, comprising: a step of forming a system-based high melting point metal compound and heat-treating; 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.