JP2949290B2 - Manufacturing method of amorphous silicon based semiconductor film - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing an amorphous silicon-based semiconductor film that can be grown in a vapor phase at a high deposition rate by a glow discharge decomposition method.

[Prior art and its problems]

2. Description of the Related Art Recently, electronic component devices using an amorphous silicon-based semiconductor film formed by a glow discharge decomposition method (hereinafter, amorphous silicon is abbreviated as a-Si) have been put to practical use. For example, a solar cell, an optical sensor, an electrophotographic photosensitive member, a contact image sensor, and the like can be given.

However, when the a-Si film is formed by the glow discharge decomposition method, there is a problem that the film formation rate is low.

In the case of the a-Si photosensitive drum, the thickness of the a-Si film is generally about 20 to 40 μm, and the large thickness of the a-Si film results in a time required for manufacturing of about 5 to 10 hours.

[Object of the invention]

The present inventors have made intensive studies in view of the above circumstances, and as a result, in the glow discharge decomposition method, the gas pressure and high-frequency power inside the reaction chamber and the amount of gas flowing into the reaction chamber were set within predetermined ranges, respectively. In such a case, it was found that the film formation rate was significantly increased.

Accordingly, the present invention has been completed based on the above findings, and an object of the present invention is to provide a method for producing an a-Si-based semiconductor film with a high film formation rate.

[Means for solving the problem]

The method for producing an a-Si-based semiconductor film according to the present invention is such that the inside of a reaction chamber into which an a-Si-based semiconductor film
At a gas pressure of ~ 0.1 Torr, the ratio of the high-frequency power applied to the gas to the amount of gas flowing into the reaction chamber is set to 1 to 6 W / sccm, and the photoconductive layer is formed by glow discharge. .

 Hereinafter, the present invention will be described in detail.

In order to form the a-Si film at a high speed, it is conceivable to increase the amount of gas flowing into the reaction chamber or to increase the applied high frequency power.
High frequency power of ~ 300W is adopted as a manufacturing condition.

On the other hand, in the present invention, the gas pressure inside the reaction chamber is set within the range of 0.01 to 0.1 Torr, and the ratio of the high-frequency power to the inflow gas amount (hereinafter abbreviated as the power / gas amount ratio) is set. When set within the range of 1-6W / sccm,
A feature is that a high film formation rate can be obtained.

The reason for limiting the numerical value in this way is that the gas pressure is 0.01 Torr
When the pressure is less than 0.1 Torr, the high-frequency power is not sufficiently transmitted to the inflow gas, and when the pressure exceeds 0.1 Torr, the reaction speed in the gas phase increases, and the amount of powder generated increases. This is because the above film formation rate becomes small.

If the power / gas amount ratio is less than 1 W / sccm, the power required to decompose the inflowing gas is insufficient, so that undecomposed gas is discharged and the gas use efficiency is reduced. Meanwhile, 6W
If it exceeds / sccm, excess power is applied as compared to the power required to decompose the inflowing gas, thereby lowering the power efficiency.

In the present invention, the object of the present invention can be achieved by adding at least one element of carbon, germanium, tin, oxygen, and nitrogen to the a-Si film. When the composition ratio between the additional element A and silicon Si is expressed as Si1-xAx, the x value may be within the range of 0 <x <0.5.

Various gases as described below are mentioned as vapor growth gases used for producing such a-Si based semiconductor films.

SiH ₄ , Si ₂ H ₆ , Si ₃ H ₈ , SiF ₄ ,
There are SiHF ₃ , SiH ₂ F ₂ , SiH ₃ F and the like.

GeF ₄ , Ge ₂ H ₆ , Ge ₃ H ₈ , G
eF ₄ and others.

CH ₄ , C ₂ H ₂ , C ₂ H ₄ , C ₂ H ₆ , C
F ₄ , C ₆ H _6-n F _n and the like.

Examples of tin element-containing gases include SnH ₄ and Sn (CH ₃ ) ₄ .

O ₂ N ₂ , NO, N ₂ O, NH ₃ as a gas containing oxygen or nitrogen element
and so on.

Furthermore, besides the gas for vapor phase growth, the periodic table III
A doping gas containing a group a element or a group Va element and a carrier gas are mixed as necessary.

The doping gas include _{B 2 H 6, PH 3,} BF 3, AsH 3,
The valence electrons of the a-Si based semiconductor film formed by these gases can be controlled.

The carrier gas is a gas for transporting all the above-mentioned gases, and includes, for example, an H ₂ gas or an inert gas such as He, Ne, or Ar.

Thus, according to the production method of the present invention, a high film formation rate of 10 μm / hour or more, and further, 70 μm / hour or more was obtained by setting the film formation conditions as described above. Moreover, the quality of the film obtained in this way was measured by using an electron spin resonance device (ESR) to measure the spin density corresponding to the defect density, and was found to be 2 × 10 ¹⁶ / cm ³ or less. Was confirmed.

〔Example〕

 Next, the present invention will be described in detail with reference to examples.

(Outline of glow discharge decomposition apparatus) The glow discharge decomposition apparatus used in this example is as shown in FIG.

In the figure, reference numeral 1 denotes a cylindrical reaction vessel made of metal, and inside the reaction vessel 1, a cylindrical glow discharge electrode plate 2 is provided.
Further, a cylindrical substrate indicator 3 and a cylindrical substrate 4 mounted on the substrate indicator 3 are installed inside the electrode plate 2. Further, the substrate support 3 is disposed on the substrate mounting body 5, a thin tubular heater section 6 is connected to the substrate mounting body 5, and the substrate support body 3 is heated by the heater section 6, and 4 is also heated. In addition, a motor unit 7 is provided on the upper part of the reaction vessel 1, and the motor unit 7 is connected to the substrate support 3. Then, the substrate 4 is rotated together with the substrate support 3 by the motor unit 7.

Reference numeral 8 denotes a gas introduction part, and 9 denotes a gas ejection part formed in a large number on the electrode plate 2. The gas for a-Si based semiconductor film vapor phase growth is introduced from the gas introduction part 8, and passes through the gas ejection part 9. Substrate 4
Is sprayed on the surface and is subjected to glow discharge. Then, the residual gas of the discharge is discharged from the gas discharge unit 10. The arrow in the figure indicates the direction of the gas flow.

Reference numeral 11 denotes a high-frequency power source, one output terminal of which is grounded to the ground side, the other output terminal of which is connected to the peripheral wall of the reaction vessel 1 and connected to the electrode plate 2 electrically connected to the peripheral wall. Glow discharge power is applied.

According to the glow discharge decomposition apparatus having the above-described configuration, the substrate 4 is set at a required temperature, and a glow discharge is generated between the substrate 4 and the electrode plate 2 while rotating. As the use gas decomposes, a
-The Si-based semiconductor film grows in vapor phase.

(Example 1) SiH ₄ gas was introduced into the glow discharge decomposition apparatus at 600 sccm, the substrate temperature was set at 260 ° C., the gas pressure was set at 0.05 to 0.5 Torr, and the power / gas amount ratio was set at 0.3 to 3.3 W / sccm. When the film forming rate was measured, the result as shown in FIG. 2 was obtained.

In the figure, ○, ● and △ are measurement plots, and a,
b, c are power / gas amount ratios of 0.3, 1.3, 3.3 W / sccm respectively
Represents a film forming speed characteristic curve in the case of.

As is clear from the results shown in FIG. 2, when the power / gas amount ratio is small, that is, in a low power power region, the film forming speed increases as the gas pressure is increased.
It reaches saturation at around 3 Torr. On the other hand, when the power / gas amount ratio is large, that is, in the high power power region, it can be seen that the growth rate tends to increase as the gas pressure decreases.

(Example 2) Next, when the film formation rate with respect to the ratio of the power / gas amount in the region where the gas pressure was low was measured, the result as shown in FIG. 3 was obtained.

In the figure, ○, ● and △ marks indicate gas pressure of 0.5T respectively.
It is a measurement plot in the case of setting to orr, 0.3 Torr, and 0.05 Torr, and d, e, and f represent the film forming rate characteristic curves.

As is clear from FIG. 3, the curve f, that is, when the gas pressure is 0.
In the case of 05 Torr, it can be seen that the film forming rate increases as the power / gas amount ratio increases.

However, it can be seen that the curve d, that is, when the gas pressure is 0.5 Torr, tends to saturate the film forming speed even when the ratio of the power / gas amount is increased.

The present inventors have set the gas pressure within the range of 0.01 to 0.1 Torr and the ratio of electric power / gas amount within the range of 1 to 6 W / sccm by the above-described embodiment and various repetitive experiments, and thereby, a high film formation can be achieved. It was confirmed that speed could be obtained.

(Example 3) In this example, the gas pressure was set to 0.05 Torr, the high frequency power was set to 2 kw, the substrate temperature was set to 260 ° C., and SiH ₄ gas was diluted with H ₂ gas at 600 sccm as a gas for vapor phase growth. Done B
The ₂ H ₆ gas was introduced at 15～200Sccm, Thus, the ratio B ₂ H ₆ / SiH ₄ of B ₂ H ₆ amount with respect to SiH ₄ amount (absolute amount of B ₂ H ₆ gas excluding H ₂ gas) When the photoconductive layer and the dark conductive layer were changed in the range of 0 to 1000 ppm and various photosensitive layers were formed and the photoconductive and dark conductive layers were measured, the results as shown in FIG. 4 were obtained.
The photoconductivity was determined by irradiating monochromatic light having a wavelength of 600 nm with a light amount of 50 μW / cm ² .

In the figure, the circles and the circles indicate measurement plots of photoconductivity and dark conductivity, respectively, and g and h indicate respective conductivity characteristic curves.

As is clear from FIG. 4, it was confirmed that good photoconductive characteristics were obtained under the condition that a high film formation rate was obtained, and that valence electrons could be controlled by doping.

Example 4 In this example, an a-Si blocking layer and an a-Si photoconductive layer were sequentially formed on the substrate 4 under the conditions shown in Table 1, and the spectral sensitivity of the a-Si photoconductor was measured. And the results as shown in FIG. 5 were obtained.

In this measurement result, the value of the spectral sensitivity is shown as the reciprocal of the half-life exposure amount when the surface of the photoreceptor is charged at a potential of 400 V and then irradiated with monochromatic light of various wavelengths of 50 μW / cm ² .

In FIG. 5, a circle indicates a spectral sensitivity measurement plot, and i indicates a characteristic curve thereof.

As is clear from the figure, it shows good photosensitivity to light having a wavelength in the range of 500 to 700 nm and is suitable as an electrophotographic photosensitive member.

(Example 5) In this example, when the film formation rate with respect to the power / gas amount was measured using Si ₂ H ₆ gas as the gas for vapor phase growth, the result as shown in FIG. 6 was obtained.

In the figure, ○ and Δ indicate gas pressure of 0.05 Torr, respectively.
And measurement plots when set to 0.5 torr, j, k
Represents each film forming speed characteristic curve.

As is clear from the results shown in FIG. 6, it can be seen that the curve j indicates that the film-forming speed increases as the power / gas amount ratio increases. However, in the curve k, the power /
It is understood that when the ratio of the gas amount is increased, the deposition rate tends to be saturated.

In addition, when the results shown in FIG. 6 are compared with the results shown in FIG. 3, it is found that the use of Si ₂ H ₆ gas significantly increases the film formation rate as compared with the Si ₂ H ₄ gas.

That is, when compared at the same gas flow rate, Si ₂ H ₆ gas is S
Approximately twice as much high-frequency power was required as compared to iH ₄ gas, thereby increasing the deposition rate by about twice.

From the above results, it is considered that under the condition of low gas pressure, the gas decomposition efficiency was further increased as the power / gas amount ratio was increased. The present inventors have confirmed that the amount of generated powder is further reduced.

(Example 5) Next, when a mixed gas of SiH ₄ gas and GeH ₄ gas was used as a gas for gas phase growth, and gas phase growth was carried out under the following film forming conditions (i), about 5 μm / hour was obtained. Film deposition rate,
Then, when the composition ratio of the Si element and the Ge element was measured, it was Si _0.8 Ge _0.2 .

Film forming conditions (i) SiH ₄ gas amount: 600 sccm GeH ₄ gas amount: 100 sccm Gas pressure: 0.5 orr Power / gas amount ratio: 1 W / sccm However, under the following film forming conditions (ii) After performing vapor phase growth, the film formation rate was about 25 μm / hour, and the composition ratio was Si
_0.6 Ge _0.4 .

Film formation conditions (ii) SiH ₄ gas amount: 600 sccm GeH ₄ gas amount: 400 sccm Gas pressure: 0.05 orr Power / gas amount ratio: 3 W / sccm (Example 6) Gas for vapor phase growth Was performed under the following film forming conditions (iii) using a mixed gas of SiH ₄ gas and C ₂ H ₂ gas as a gas deposition rate of about 8 μm / hour.
When the composition ratio of the element and the C element was measured, Si _0.6 C _0.4
Met.

Film forming conditions (iii) SiH ₄ gas amount: 600 sccm C ₂ H ₄ gas amount: 300 sccm Gas pressure: 0.5 Torr Power / gas amount ratio: 1 W / sccm However, the following film forming conditions (iv ), The film deposition rate was about 28 μm / hour, and the composition ratio was Si
_0.7 C _0.3 .

Film formation conditions (iv) SiH ₄ gas amount: 600 sccm C ₂ H ₄ gas amount: 300 sccm Gas pressure: 0.05 Torr Power / gas amount ratio: 3 W / sccm (Example 7) Vapor phase growth Using a mixed gas of SiH ₄ gas and SnH ₄ gas as the application gas, and performing a vapor phase growth under the following film forming conditions (V), a film forming rate of about 5 μm / hour was obtained. When the composition ratio of the C element was measured, it was Si _0.8 C _0.2 .

Film forming conditions (V) SiH ₄ gas amount: 600 sccm SnH ₄ gas amount: 100 sccm Gas pressure: 0.5 Torr Electric power / gas amount ratio: 1 W / sccm However, under the following film forming conditions (vi) After vapor phase growth, the film formation rate was about 19 μm / hour, and the composition ratio was Si
_0.9 C _0.1 .

Film formation conditions (vi) SiH ₄ gas amount: 600 sccm SnH ₄ gas amount: 100 sccm Gas pressure: 0.05 Torr Power / gas amount ratio: 3 W / sccm (Example 8) Gas for vapor phase growth As shown in Table 2, any one of oxygen (O ₂ ) gas, nitrogen (N ₂ ) gas, dinitrogen monoxide (N ₂ O) gas, ammonia (NH ₃ ) gas and SiH ₄ gas is used as the gas. Vapor phase growth was performed under the film forming conditions, and the film forming speed and the film composition ratio were measured.

As is clear from the results shown in Table 2, the sample No. (1-
A), (2-A), (3-A) and (4-A) correspond to sample Nos. (1-B), (2-B), (3-B) and (4-A), respectively.
It can be seen that a higher film formation rate was obtained as compared with B).

〔The invention's effect〕

As described above, according to the method for manufacturing an a-Si-based semiconductor film according to the present invention, the film formation rate is significantly increased, thereby improving the manufacturing efficiency and the manufacturing cost.

Further, in the conventional method for producing an a-Si-based semiconductor film, there is a problem that powder adheres to the inside of the reaction chamber for glow discharge as the film is formed. According to the publication, since the high film forming rate was obtained, the generation amount of the powder was remarkably reduced, whereby the powder did not contaminate the a-Si film. Moreover, the obtained a-Si
The system-based semiconductor film has excellent photoconductivity, and as a result, a high-quality and highly-reliable a-Si-based semiconductor film can be provided.

Further, in the above-described embodiment, the case where the a-Si photosensitive drum is manufactured has been described as an example.
The present invention can be applied to various electronic component devices such as an optical sensor, a contact image sensor, and a TFT, and can be provided as a low-cost and high-quality device.

[Brief description of the drawings]

FIG. 1 is a schematic view of a glow discharge decomposition apparatus, and FIGS.
FIG. 4 is a diagram showing a film forming rate, FIG. 4 is a diagram showing electric conductivity,
FIG. 5 is a diagram showing the spectral sensitivity, and FIG. 6 is a diagram showing the film forming speed. 2 ... Glow discharge electrode plate 4 ... Substrate 8 ... Gas introduction part

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C23C 16/22-16/42

Claims (2)

(57) [Claims] A reaction chamber is filled with a vapor growth gas at a gas pressure of 0.01 to 0.1 Torr to vapor-grow an amorphous silicon semiconductor film having photoconductivity on a substrate surface. A method for producing an amorphous silicon-based semiconductor film in which a photoconductive layer is formed by glow discharge in a state where the ratio of the applied high-frequency power to the amount of gas flowing into the reaction chamber is 1 to 6 W / sccm. 2. A glow discharge of a vapor growth gas containing at least one of a carbon element-containing gas, a germanium element-containing gas, a tin element-containing gas, an oxygen element-containing gas, and a nitrogen element-containing gas to produce carbon, germanium, and tin. ,
The composition ratio of the additive element A comprising at least one of oxygen and nitrogen and the silicon element Si is represented by Si _1-x A _x and 0 <x <0.5.
The method for producing an amorphous silicon-based semiconductor film according to claim 1, wherein a photoconductive layer is formed.