JPH0755809B2 - Method for forming high carbon content amorphous silicon film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] A method of forming a high carbon content amorphous silicon (a-Si _1-x C _x : H) film applied to a surface protective layer of an electrophotographic photoreceptor, When a substrate is set in the deposition space where plasma is excited and the source gas is supplied and a high carbon content amorphous silicon film is formed on the surface for the purpose of preventing the denseness and moisture resistance from being impaired. In addition, hydrogen radicals generated by decomposing hydrogen gas by microwaves are sent into the deposition space to form a film.

[Industrial application field]

The present invention relates to a method of forming a high carbon content a-Si _1-x C _x : H film applied to a surface protective layer of an electrophotographic photoreceptor.

The a-Si photoconductor used as an electrophotographic photoconductor is regarded as a promising one because it has high durability and is non-polluting. This photoreceptor is generally constituted by sequentially forming a blocking layer, a photosensitive layer which is a photoconductive layer, and a surface protective layer on a substrate.

[Conventional technology]

Of these, the surface protective layer is required to have excellent insulating properties and excellent translucency in order to prevent carrier injection from the surface to the photosensitive layer. Conventional carbon-containing amorphous silicon (a-Si _1-x Among C _x : H), those with a low carbon content of x <0.5 have been widely used.

[Problems to be Solved by the Invention]

While this a-Si _1-x C _x : H (x <0.5) has sufficient hardness, the photoconductor using this surface protection layer has the drawback that image deletion easily occurs in high humidity. . This image flow is due to the hygroscopicity of Si contained in the a-Si: H film, because Si-OH, H-OH groups, etc. are adsorbed on the surface during corona irradiation under high humidity conditions and the potential flows. It is thought to occur in. The following will be described in detail.

Fig. 4 shows a-Si _1-x C _x : H (x =
0.5) The surface condition when the film was exposed to corona by a -5KV corotron, and measured by high-sensitivity reflection FT-IR (FT-IR-RAS). This figure shows that as the corona irradiation time increases, Si-O-Si (1100 to 1200cm ^-1 ) and Si-OH (3650cm
It can be seen that the peaks of ^-1 ) and H-OH (3300 to 3400 cm ^-1 ) increase. Fig. 5 shows the contact angle at that time.
After 60 minutes, it can be seen that the contact angle is close to 0 ° (part I). The contact angle represents the wettability with water. The larger this angle is, the better the water repellency is and the less water is absorbed. In the experiment of FIG. 5, 60 minutes after corona irradiation
When the a-SiC: H film was washed with methanol and dried by nitrogen blow, the contact angle was recovered to 40 ° (II part). The recovery of this contact angle is measured by IR-RAS, and Si-OH, H-OH
It turns out that it happens because the base etc. disappears. Image flow due to adsorption of Si-OH and H-OH groups is considered to occur in the following process. First, water is decomposed by ozone generated by corona irradiation and adsorbed in the form of Si-OH on the surface of a-SiC: H film to increase the polarity. The polar molecule water (H-OH) is further adsorbed there. When charged in this state, electric charges flow into the conductive water, the latent image is blurred, and as a result, image deletion occurs. From these results, it can be seen that it is desirable to reduce hygroscopic Si in the surface protective layer of the photoconductor. Therefore, the carbon content is high
Although an a-SiC: H film is desired, a dense high carbon content a-SiC: H cannot be produced by the conventional manufacturing method. This will be described in detail as follows.

FIG. 6 is a schematic view of a conventional a-SiC: H film forming apparatus.
1 to 4 are cylinders for supplying raw material gas. For example, cylinder 1 is Si ₂ H ₆ , cylinder 2 is C ₃ H ₈ , cylinder 3 is H ₂
However, each cylinder 4 contains Ar. During film formation, these gases are controlled by the flow rate controller 5 and introduced into the vacuum container 6. Then, the RF power source 8 is applied to the two electrodes 7, 7 '.
To generate plasma by applying 13.56MHz RF power.
A film is deposited on the substrate 9. Exhaust is performed by the mechanical booster pump 10 and the rotary pump 11. When a photoconductor having a surface protective layer of high carbon content a-Si _1-x C _x : H (x ≧ 0.5) is produced by using this apparatus, a photoconductor having no charging potential is produced. It is considered that this is because the denseness of the a-SiC: H film was impaired.

Therefore, there is a need for an a-SiC: film that does not impair the denseness even when it contains a high amount of carbon, and does not adsorb Si-OH, H-OH, etc. even during corona irradiation in high humidity, and a method for producing the film.

It is an object of the present invention to provide a method for forming a high carbon content amorphous silicon film which does not impair the denseness and moisture resistance of the film surface.

[Means for Solving the Problems]

In order to achieve the above object, in the present invention, hydrogen gas is used when a substrate is set in a deposition space where plasma is excited and a source gas is supplied and a high carbon content amorphous silicon film is formed on the surface of the substrate. A hydrogen radical generated by being decomposed by microwaves is fed into the deposition space to form a film.

[Action]

Since hydrogen is supplied to the deposition space in the form of hydrogen radicals, the surface of the reactive species decomposed during film formation is covered with hydrogen to improve the density. This effect cannot be achieved by the method of introducing hydrogen gas together with the raw material gas which has been attempted conventionally. In this conventional method, it is considered that the surface of the decomposed species could not be sufficiently covered with hydrogen because there was insufficient energy to decompose hydrogen.

Therefore, when the surface protective layer of the electrophotographic photoreceptor is formed by the method of the present invention, the hygroscopic Si can be reduced without impairing the compactness, and the problem of image deletion can be solved. .

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS.

When forming an a-SiC: H film containing a high carbon content, it is desired that the surface of the reactive species deposited on the substrate by decomposition is covered with hydrogen in order to improve the denseness. Therefore, the conventional method (RF
In the -CVD method), a method of introducing hydrogen gas together with the raw material gas has been tried, but sufficient results have not been obtained. This is probably because there was not enough energy to decompose hydrogen.

Therefore, in the present invention, the problem is solved by decomposing hydrogen gas by microwaves and sending it into the deposition space in the form of hydrogen radicals. Next, the method of the present invention will be described with reference to FIGS.

FIG. 1 is a plan view showing the structure of a thin film forming apparatus for carrying out the present invention, and FIG. 2 is a perspective view thereof, in which 21 is a microwave oscillator, 22 is a waveguide, and 23 is a quartz tube. 24 is a plasma generation furnace, 25 is a hydrogen gas introduction part, 26 is a vacuum container, 27 is a heater 28
By the base, 29 is the RF electrode, 30 is the source gas (Si
₂ H ₆ , C ₃ H ₈ etc.) introduction part, 31 is an RF power supply, 32 is a mechanical booster pump, and 33 is a rotary pump.

At the time of film formation, the
A base body on a base 27 that forms a deposition space 34 between the RF electrode 29 and
Set 100 and heat it to 250 ℃ with heater 28,
₂ cc / min of Si ₂ H ₆ from the source gas introduction part 30 into the deposition space 34
C ₃ H ₈ at a flow rate of 20 cc / min and RF
RF power of 100 W is supplied from the power supply 31 to the RF electrode 29. At the same time, H ₂ was supplied from the hydrogen gas inlet 25 at a flow rate of 100 cc / min, and this was decomposed by the microwave of power 380 W supplied from the microwave oscillator 21 through the waveguide 22 in the plasma generation furnace 24. The hydrogen radicals are supplied to the deposition space 34.
At this time, the pressure in the vacuum container 26 is set to 0.1 by the pumps 32 and 33.
Keep torr. The _{x of the} a-Si _1-x C _x : H film formed on the surface of the substrate 100 by this step is 0.8, and even when corona irradiation is applied in high humidity of 80% RH, Si- O-Si, Si-OH,
No increase in H-OH peak was observed, indicating that the moisture resistance was improved. Further, the denseness of the film is not impaired.

The effects of using this a-SiC: H film as the surface protective layer of the photoreceptor 101 shown in FIG. 3 are as follows.

In FIG. 3, 102 is an Al substrate, 103 is a 0.56 μm thick B (boron) highly doped a-Si: H blocking layer, 104
Is a B lightly doped a-Si: H photosensitive layer with a film thickness of 10 μm, and 105 is an a-Si film with a film thickness of 0.18 μm formed on the surface by the above process.
_0.2 C _0.8 : H surface protective layer. By adopting the above-described configuration of the photoconductor 101, it was possible to obtain the one having good electric characteristics such as a charging potential of 500 V, a residual potential of 5 V, and a half exposure amount of 1.0 μJ / cm ² . Further, it was confirmed that image deletion did not occur in an atmosphere of 35 ° C. and 85% RH, and that it had excellent moisture resistance.

〔The invention's effect〕

As described above, according to the present invention, by feeding hydrogen radicals into the deposition space, it is possible to form a dense and moisture-resistant high carbon content a-SiC: H film that could not be obtained by the conventional method. became. By using this film as the surface protective layer of the photoreceptor, it was possible to prevent image deletion in high humidity.

[Brief description of drawings]

FIG. 1 is a plan view showing the structure of a thin film forming apparatus according to an embodiment of the present invention, FIG. 2 is a perspective view thereof, and FIG. 3 is a sectional view showing the constitution of a photoconductor to which the present invention is applied. 5 is a graph for explaining the conventional problems, and FIG. 6 is a schematic view of a conventional a-SiC: H film forming apparatus, in which 21 is a microwave oscillator, 24 is a plasma generation furnace, and 25 is Hydrogen gas inlet, 29 RF electrode, 30 source gas inlet, 31 RF
A power source, 34 is a deposition space, and 100 and 102 are substrates.

Claims (1)

[Claims] 1. When a substrate (100) is set in a deposition space (34) into which plasma is excited and a raw material gas is supplied and a high carbon content amorphous silicon film is formed on the surface of the substrate (100), hydrogen gas is used as a micro gas. A method for forming a high carbon content amorphous silicon film, characterized in that hydrogen radicals generated by decomposition by waves are fed into the deposition space (34) to form a film.