JPH0573830B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a film containing polysilane as a main component by a low temperature reduced pressure vapor phase method (referred to as LT CVD method).

This invention uses polysilane as a reactive gas at 370 to 650
By heating the surface to a temperature of 150°C and decomposing it, and keeping the surface on which it is formed at a temperature of 150 to 350°C, a silicon-based non-containing material containing an amorphous structure with hydrogen added as a recombination center neutralizing agent is produced. The present invention relates to a method for manufacturing a single crystal semiconductor.

This invention is a method for performing LT CVD using a reactive gas of silane including monosilane.
The method is characterized in that by irradiating the surface to be formed or the reactive gas with ultraviolet light having a wavelength of less than m, the density of the reactive gas is increased and the rate of film formation is increased. That is, it is characterized by the combined use of the optical CVD method and the LT CVD method.

The present invention is characterized in that it does not cause spatter (damage) on the surface on which the film is formed, which is observed when using the plasma CVD method, and in addition, it increases the substantial growth rate of the film.

Conventionally, the reduced pressure vapor phase method (hereinafter referred to as CVD method)
In this method, the inside of the reactor was kept under reduced pressure, the substrate having the surface to be formed had the highest temperature, and the temperature of the reactive gas was equal to or lower than that.

As an example, an invention by the present inventor (Tokuko Sho
51-1389 Method of forming polycrystalline semiconductor film, Special Publication 1987
-49133 Method of forming semiconductor film, Special Publication No. 53-14518
A method for manufacturing a silicon nitride film, a method for manufacturing a semiconductor device in Japanese Patent Publication No. 53-33667, and a method for manufacturing a silicon oxide film in Japanese Patent Publication No. 56-52877 are known.

However, the method of the present invention, on the contrary, relates to a low-temperature gas phase reaction method characterized in that the temperature of the surface to be formed is lower than the temperature of the reactive gas. Furthermore, the present invention is characterized by the LT CVD method using polysilane as a reactive gas or the LT CVD method using silane in combination with light energy. The constituent requirement is that hydrogen be added to the semiconductor film at a concentration of 1 to 15 atom%, and the semiconductor film can be formed at a rate of 50 Å/min or more without sputtering (damaging) the surface to be formed. A high film growth rate was obtained.

The present invention will be described below with reference to the drawings.

FIG. 1 shows an outline of the horizontal CVD apparatus used in the present invention.

In the drawing, the reaction system 10 includes a quartz reactor 2,
Light with a wavelength of 300nm or less, e.g. 185nm, 254nm
a mercury lamp 9 that supplies light energy, a resistance heating furnace 3 that performs external heating to heat a reactive gas, an oil film 48 that prevents a film from being coated on quartz, a substrate 1 having a surface to be formed, a substrate holder 4, and a holder. A cooling medium supply source 5, a flow meter 6, and a nozzle 8 were used to set the temperature to a predetermined temperature.

After cooling the substrate 1 to a predetermined temperature of 150 to 350°C,
It is discharged to the outside by a vacuum pump 7.

In this drawing, nitrogen was used as the cooling medium. To the gas system 20, polysilane (the main component is disilane [Si ₂ H ₆ ]) or silane, generally monosilane (SiH ₄ ), was added through a flow meter 29 and a valve 28 . Further, hydrogen as a carrier gas or purge gas was supplied from 27.

The exhaust system 30 is connected to the vacuum pump 12 via the valve 13.
Exhaust by.

Figure 2 shows the growth rate of a film produced by the LT CVD method in the reactor shown in Figure 1.

In the drawing, the relationship between the temperature of the coating surface and the coating growth rate is shown. Curve 15 has a space temperature of 370°C, 500°C 16, 570°C 17, and 650°C 18, respectively. In this case, the disilane is 5 c.c./min, and the pressure is 10 ~
0.5torr, especially 2torr. When monosilane (SiH ₄ ) was used instead of disilane, only curve 14 was obtained. It has been impossible to achieve a practical film growth rate (more than 50 Å/min) at temperatures below 400°C, preferably from 350 to 150°C, containing hydrogen.

On the other hand, as shown in the present invention, using polysilane increases the film growth rate from 50 Å/min to 150 Å/min.
It has been found that the process can be carried out within a practically possible range of Å/min, and is extremely effective.

In Figure 2, the temperature of the reaction space is
650℃ (curve 18), 570℃ (curve 17), 470℃
(Curve 16) and 370°C (Curve 15).

Furthermore, if the temperature of the surface to be formed is 150℃ or less,
What was formed was a mixture of flakes in addition to the film, making it impossible to obtain semiconductor characteristics in practice. For such a reaction temperature, ultraviolet light having a wavelength of 300 nm or less (5 to 500 mW/cm2, e.g. 250 mW/cm ²
W/cm ² ) and carried out as PhotoLT CVD. As a result, even when monosilane was used, the film growth rate could be further improved from curve 14 to curve 24. What is more important is the electrical properties of the formed film. That is, as shown in Fig. 1, when ultraviolet light (254 nm, 185 nm) is irradiated, even if the silicon film is not doped with impurities, the power of AM1 (100 mW/cm ² ) is 8.
×10 ⁴ (Ωcm) ^-1 and dark conductivity of 3 × 10 ¹¹ (Ωcm) ^-1 were obtained. When not irradiating ultraviolet light, use 1×
10 ⁴ (Ωcm) ^-1 and 1×10 ¹⁰ (Ωcm) ^-1 . That is, it has been found that the photosensitivity can be improved by one order of magnitude or more.

When this was used in combination with ultraviolet light to form a reactive gas for polysilane, a six-digit photosensitivity could be obtained.

In the method of the present invention, the content of impurities is
When examined using SIMS (3F model manufactured by Camera Company) and FTIR (Fourier infrared spectroscopy), the amount of oxygen in it is less than 5×10 ¹⁷ cm ^-3 and the amount of carbon is 5×10 ¹⁷ cm ^-3
It was below. This is presumed to be because, in the method of the present invention, water or hydrocarbons as impurities do not react with disilane at such temperatures, and as a result, silicon oxide and silicon carbide as reaction products are not incorporated into the film.

This means that when compared to the PCVD method (plasma vapor phase reaction method), the degree of impurity contamination is generally 1
Considering that it is ~20×10 ¹⁹ cm ⁻³ , it has been found that an industrial margin can be given to the purity of the starting material.

Furthermore, when ultraviolet light was irradiated, even if the reactive gas was monosilane, the film growth rate could be changed from curve 14 in FIG. 2 to curve 24. Therefore, the light energy was 1 KW output (250 mW/cm ² for a substrate area of 2×20 cm ² (40 cm ² )).

The fact that it has become possible to decompose silane without using mercury excitation by using thermal energy at a temperature of 370 to 650°C has an extremely large industrial effect. In particular, polysilane has a
Whereas monosilane costs 10,000 to 20,000 yen per gram.
Considering that the price is 100 to 130 yen, it is estimated that even if light energy is required for the reaction, it will be commercially viable.

In addition, in the method of the present invention, as a reactive gas
The LT CVD method is characterized by the use of polysilane, or the combination of light energy and the use of monosilane or polysilane in the LT CVD method. However, when carrying out the method of the present invention, these are P containing simultaneously added diborane or phosphin as a valence or valence impurity.
Alternatively, an N-type hydrogen-doped silicon semiconductor may be formed.

In the present invention, in far infrared rays of 8μ or more, especially at wavelengths of 10 to 13μ where Si-H resonance absorption occurs,
Adding light energy of 1 W/cm is also effective, as is ultraviolet light irradiation.

Furthermore, by adding phosphin, methane, and germane as additives to silicon semiconductors, Si _x C _1-x (0<
x<1), Si ₃ N _4-x (0<x<4), Si _x Ge _1-x (0<
x<1).

[Brief explanation of the drawing]

FIG. 1 shows an outline of the apparatus used in the present invention. FIG. 2 shows the characteristics of the film growth rate obtained by the method of the present invention.

Claims (1)

[Scope of Claims] 1. When a reactive gas containing polysilane as a main component is introduced under reduced pressure to produce a film containing hydrogen as a main component and non-single-crystal silicon added to the surface to be formed, the reactive gas is A reduced pressure vapor phase method characterized in that gaseous polysilane is heated to a temperature of 370 to 650°C, and the surface of the coating is maintained at 150 to 350°C. 2. When introducing a reactive gas mainly composed of silane under reduced pressure and producing a film mainly composed of non-single crystal silicon to which hydrogen has been added to the surface to be formed, the reactive gas silane is While heating to a temperature of 650°C, the coating surface is maintained at 150 to 350°C, and in addition, optical energy of ultraviolet light with a wavelength of 300 nm or less or far infrared light with a wavelength of 8 μ or more is applied to the surface to be formed or the reactive gas. A reduced pressure vapor phase method characterized by irradiation.