Method of manufacturing amorphous silicon electrophotographic photosensitive member

A method for stably manufacturing, with improved reproducibility, a good amorphous silicon electrophotographic photosensitive member improved in potential characteristics such as chargeability and photoresponse as well as in the effect of reducing photo-memory and defects which cause spot image defects. A film is formed by plasma CVD on a base of the photosensitive member by using electromagnetic waves having a frequency of 13.56 MHz or higher as power for forming plasma under conditions that the spatial potential of plasma generated by the electromagnetic waves with respect to a base of the photosensitive member is not higher than 120 V and the current density of ions incident upon the base is not lower than 0.4 mA/cm.sup.2.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a method for manufacturing a photosensitive 
member for electrophotography composed of amorphous silicon, amorphous 
silicon carbide or the like (hereinafter referred to as "a-Si") with 
improved reproducibility and stability. 
2. Description of the Related Art 
In the field of image forming, there is a need for photoconductive 
materials forming photosensitive members for electrophotography to have 
certain characteristics: a high sensitivity, a high S/N ratio 
photocurrent (Ip)/dark current (Id)!, an absorption spectrum matching 
with spectrum characteristics of irradiated electric waves, a fast 
photo-response, a desired dark resistance value, and causing no harm to 
the human body during use. In the case of an electrophotographic 
photosensitive member incorporated in electrophotographic apparatuses used 
for office work or the like, the quality of being harmless during use 
mentioned above is particularly important. It is also important that the 
electrophotographic photosensitive member should have little impact upon 
the environment after the completion of the useful life of the apparatus. 
From this viewpoint, attention has been directed again to amorphous silicon 
as a photoconductive material. For example, in German Patent Laid-Open 
Publication Nos. 2746967 and 2855718, applications of amorphous silicon as 
an electrophotographic photosensitive material are described. 
In German Patent Laid-Open Publication No. 3046509 there is proposed an 
electrophotographic photosensitive member formed of an electroconductive 
support and an a-Si photoconductive layer having halogen atoms as a 
constituent. According to the art disclosed in this publication, 
electrical and optical characteristics suitable for a photosensitive layer 
of an electrophotographic photosensitive member can be achieved by adding 
1 to 40 atomic percent of halogen atoms to a-Si. 
On the other hand, amorphous silicon carbide (hereinafter referred to as 
"a-SiC") is known as a material having high heat resistance and high 
surface hardness, having a high dark resistivity in comparison with a-Si 
and capable of exhibiting an optical band gap through the range of 1.6 to 
2.8 eV by selecting the carbon content. In U.S. Pat. No. 4,471,042 there 
is proposed an electrophotographic photosensitive member having a 
photoconductive layer formed of such a-SiC. In the art disclosed in this 
publication, a photoconductive layer of an electrophotographic 
photosensitive member is formed by using a-Si containing 0.1 to 30 atomic 
percent of carbon as a chemical modifier to achieve improved 
electrophotographic characteristics, i.e., high dark resistance and high 
photo-sensitivity. 
Further, in Japanese Patent Publication No. 63-35026 there is proposed an 
electrophotographic photosensitive member having, on an electroconductive 
support, an intermediate layer of a-Si having carbon atoms and hydrogen 
atoms and/or fluorine atoms as constituents (hereinafter referred to as 
"a-SiC (H, F)", and an a-Si photoconductive layer. The a-SiC (H, F) 
intermediate layer containing at least hydrogen atoms and/or fluorine 
atoms is provided to reduce cracks and separation of the a-Si 
photoconductive layer without impairing the desired photoconductive 
characteristics. 
Plasma chemical vapor deposition (CVD) processes and sputtering processes 
are known as processes for forming such a-Si photosensitive members. Among 
plasma CVD processes used for this purpose, RF plasma CVD (RF-PCVD) 
processes are known as an ordinary forming process. An apparatus and a 
method for forming a deposited film by an RF-PCVD process will be 
described below. 
FIG. 1 is a schematic diagram showing an example of an apparatus for 
manufacturing an electrophotographic photosensitive member supported on 
RF-PCVD. This apparatus is mainly constituted of a deposition unit 2000, a 
raw material gas supply unit 2200, and an evacuation unit (not shown) for 
reducing the internal pressure of a reaction chamber 2111. In the reaction 
chamber 2111 of the deposition unit 2000, a heater 2113 for heating a 
support 2112 and pipes 2114 for introducing raw material gases having raw 
material gas introducing holes are provided. A high frequency matching box 
2115 is connected to the reaction chamber 2111. The support 2112 on which 
a layer or layers of a-Si photosensitive member are formed has, for 
example, a cylindrical shape such as that shown in FIG. 1, and is placed 
in a desired position in the reaction chamber 2111. 
The raw material gas supply unit 2200 has bombs 2221 to 2226 containing raw 
material gases necessary for forming the desired layers, e.g., SiH.sub.4, 
H.sub.2, CH.sub.4, NO, NH.sub.3, and SiF.sub.4, valves (2231 to 2236, 2241 
to 2246, 2251 to 2256), and mass flow controllers 2211 to 2216. The raw 
material gas bombs are connected to gas introducing pipes 2114 in the 
reaction chamber 2111 through a valve 2260. 
A deposited film can be formed by using this apparatus, for example, as 
described below. A cylindrical support 2112 is first placed in the 
reaction chamber 2111, and the interior of the reaction chamber 2111 is 
evacuated by the evacuation unit, not shown (e.g., a vacuum pump). Then, 
the temperature of the cylindrical support 2112 is controlled with the 
supporting member heater 2113 to be maintained at a predetermined 
temperature of 20.degree. to 500.degree. C. 
To introduce raw material gases for forming a deposited film into the 
reaction chamber 2111, the closed state of each of the valves 2231 to 2236 
of the gas bombs and a leak valve 2117 of the reaction chamber is 
confirmed, the opened state of each of the outflow valves 2251 to 2256 and 
the auxiliary valve 2260 is also confirmed, and a main valve 2118 is 
thereafter opened to evacuate the reaction chamber 2111 and a gas piping 
2116. 
Next, when a vacuum meter 2119 reads about 5.times.10.sup.-5 Torr, the 
auxiliary valve 2260 and the outflow valves 2251 to 2256 are closed. 
Thereafter, the gases are introduced from the gas bombs 2221 to 2226 by 
opening the valves 2231 to 2226, and the pressure of each gas is regulated 
at 2 kg/cm.sup.2 with pressure regulators 2261 to 2266. Then, the inflow 
valves 2241 to 2246 are gradually opened to introduce the gases into the 
mass flow controllers 2211 to 2216. 
After a film forming preparation step has been completed in the 
above-described manner, and when the temperature of the cylindrical 
support 2112 is maintained at the desired temperature, the needed outflow 
valves 2251 to 2256 and the auxiliary valve 2260 are gradually opened to 
introduce desired gases from the gas bombs 2221 to 2226 into the reaction 
chamber 2111 through the gas introducing pipes 2114. 
Next, the flow rates of the raw material gases are controlled so as to be 
set to predetermined values by the mass flow controllers 2211 to 2216. 
Simultaneously, the opening of the main valve 2118 is adjusted while 
reading the vacuum meter 2119 so that the pressure in the reaction chamber 
2111 is set to a desired pressure not higher than 1 Torr. When the 
internal pressure of the reaction chamber 2111 is stabilized, power from 
an RF power source (not shown) is set to a predetermined level, and the RF 
power is introduced into the reaction chamber 2111 through the 
high-frequency matching box 2115 to cause RF glow discharge. By the energy 
of this discharge, the raw material gases introduced into the reaction 
chamber 2111 are decomposed and a deposited film having predetermined 
silicon as a main component is formed on the cylindrical support 2112. 
When the thickness of the formed film becomes equal to a desired 
thickness, the outflow valves are closed to stop the gas flow into the 
reaction chamber 2111, thereby terminating the formation of the deposited 
film. 
The same operations are repeated a certain number of times to form a 
desired multilayer photosensitive member. 
Needless to say, when each layer is formed, the outflow valves other than 
those for introducing necessary gases are closed. Also, the operation of 
closing the outflow valves 2251 to 2256, opening the auxiliary valve 2260 
and fully opening the main valve 2118 to evacuate the system to high 
vacuum is performed to remove remaining gases in the reaction chamber 2111 
and in the piping between the outflow valves 2251 to 2256 and the reaction 
chamber 2111, if necessary. 
To improve the uniformity of film formation, the cylindrical support 2112 
may be rotated at a desired speed by a drive unit (not shown) during film 
formation. 
Needless to say, the kinds of gas and the valve operation described above 
may be changed according to conditions of formation of each layer. 
A heating member adapted to use in vacuum may be used as a means for 
heating the support. Examples of the heating member are a sheath type 
wound heater, a plate-like heater, an electrical resistance heating 
member, such as a plate heater or a ceramic heater, a heat radiating lamp 
heating member, such as a halogen lamp or an infrared lamp, and a heating 
member having heat exchange means using a liquid or a gas as a thermal 
medium. As a surface material of the heating means, a metal, such as 
stainless steel, nickel, aluminum or copper, a ceramic, a heat-resistant 
macromolecular resin or the like may be used. Other heating means may also 
be used. For example, a special heating chamber other than the reaction 
chamber may be provided to heat the support, and the heated support may be 
transported into the reaction chamber while being maintained in a vacuum. 
Next, an apparatus and a method for forming a deposited film supported on 
another kind of plasma CVD process known as a microwave plasma CVD process 
will be described. FIG. 2 is a schematic diagram of the construction of an 
example of a reactor for forming a deposited film for an 
electrophotographic photosensitive member by a microwave plasma CVD 
(hereinafter referred to as ".mu.W-PCVD"), and FIG. 3 is a schematic 
cross-sectional view of the reactor. 
An apparatus for manufacturing an electrophotographic photosensitive member 
by .mu.W-PCVD, constructed as described below, can be formed by connecting 
a deposition unit 3100 shown in FIG. 2, which is used in place of the 
deposition unit 2000 for RF-PCVD in the manufacturing apparatus shown in 
FIG. 1, to the raw material gas supply unit 2200. 
This apparatus is constituted of a reaction chamber 3111 having a vacuum 
airtight structure and capable of being evacuated, the raw material gas 
supply unit 2200, and an evacuation unit (not shown) for decompressing the 
interior of the reaction chamber. In the reaction chamber 3111 are 
provided microwave introducing windows 3112 formed of a material through 
which microwave electric power can be efficiently transmitted to the 
interior of the reaction chamber and which can maintain a vacuum airtight 
condition (e.g., quartz glass, alumina ceramic or the like), microwave 
waveguides 3113 connected to a microwave power source (not shown) through 
a stab tuner (not shown) and an isolator (not shown), support heaters 
3116, a raw material gas introducing pipe 3117, and an electrode 3118 for 
applying an external electrical bias for controlling a plasma potential. 
The interior of the reaction chamber 3111 communicates with a diffusion 
pump (not shown) through an evacuation pipe 3121. The raw material gas 
supply unit 2200 has bombs 2221 to 2226 containing necessary raw material 
gases, e.g., SiH.sub.4, H.sub.2, CH.sub.4, NO, NH.sub.3, and SiF.sub.4, as 
in the case of RF-PCVD, valves (2231 to 2236, 2241 to 2246, 2251 to 2256), 
and mass flow controllers 2211 to 2216. The raw material gas bombs are 
connected to the gas introducing pipe 3117 in the reaction chamber 2111 
through a valve 2260. A space 3130 surrounded by cylindrical supports 
3115, which are placed in the reaction chamber 3111 and on which a layer 
or layers of an amorphous silicon photosensitive member is formed, is 
formed as a discharge space. 
A deposited film can be formed by .mu.W-PCVD using this apparatus as 
described below. Cylindrical supports 3115 are first placed in the 
reaction chamber 3111 and are rotated by driving devices 3120, and the 
interior of the reaction chamber 3111 is evacuated by the unillustrated 
evacuation unit (e.g., a vacuum pump) through the evacuation pipe 3121. 
The pressure in the reaction chamber 3111 is controlled so as to be 
maintained at 1.times.10.sup.-6 Torr or lower. Then, the temperature of 
the cylindrical supports 3115 is increased and maintained at a 
predetermined temperature of 20.degree. to 500.degree. C. by the support 
heaters 3116. 
To introduce raw material gases for forming a deposited film into the 
reaction chamber 3111, the closed state of each of the valves 2231 to 2236 
of the gas bombs and a leak valve of the reaction chamber is confirmed, 
the opened state of each of the outflow valves 2251 to 2256 and the 
auxiliary valve 2260 is also confirmed, and a main valve (not shown) of 
the reaction chamber 3111 is thereafter opened to evacuate the reaction 
chamber 3111 and gas pipe system of the same. 
Next, when a vacuum meter (not shown) reads about 5.times.10.sup.-5 Torr, 
the auxiliary valve 2260 and the outflow valves 2251 to 2256 are closed. 
Thereafter, the gases are introduced from the gas bombs 2221 to 2226 by 
opening the valves 2231 to 2226, and the pressure of each gas is regulated 
at 2 kg/cm.sup.2 with pressure regulators 2261 to 2266. Then, the inflow 
valves 2241 to 2246 are gradually opened to introduce the gases into the 
mass flow controllers 2211 to 2216. 
After a film forming preparation step has been completed in the 
above-described manner, and when the temperature of the cylindrical 
supports 3115 is maintained at the desired temperature, necessary ones of 
the outflow valves 2251 to 2256 and the auxiliary valve 2260 are gradually 
opened to introduce desired ones of the gases from the gas bombs 2221 to 
2226 into the reaction chamber 3111 through the gas introducing pipe 3117. 
Next, the flow rates of the raw material gases are controlled so as to be 
set to predetermined values by the mass flow controllers 2211 to 2216. 
Simultaneously, the opening of the main valve is adjusted while reading 
the vacuum meter so that the pressure in the reaction chamber 3111 is set 
to a predetermined pressure not higher than 1 Torr. When the internal 
pressure of the reaction chamber 3111 is stabilized, microwaves having a 
frequency of 500 MHz or higher, more preferably 2.45 GHz, are generated by 
the microwave power source, the power from the microwave power source is 
set to a desired level, and microwave energy is introduced into the 
discharge space 3130 through the wave guides 3113 and microwave 
introducing windows 3112 to cause microwave glow discharge. 
Simultaneously, an electric bias, e.g., a direct current, is applied to 
the electrode 3118 from a power source 3119. As a result, in the discharge 
space 3130 surrounded by the supports 3115, the introduced raw material 
gases are dissociated by being excited with the microwave energy to form 
the desired deposited film on the cylindrical supports 3115. At this time, 
to improve the uniformity of film formation, the cylindrical supports 3115 
are rotated at a desired speed by support rotating motors 3120. 
When the thickness of the formed film becomes equal to a desired thickness, 
the supply of microwaves is stopped and the supply of the gases to the 
reaction chamber is stopped by closing the outflow valves, thereby 
terminating the formation of the deposited film. 
The same operations are repeated a certain number of times to form a 
desired multilayer photosensitive member. 
Needless to say, when each layer is formed, the outflow valves other than 
those for introducing necessary gases are closed, as in the case of 
RF-PCVD. Also, the operation of closing the outflow valves 2251 to 2256, 
opening the auxiliary valve 2260 and fully opening the main valve to 
evacuate the system to high vacuum is performed to remove remaining gases 
in the reaction chamber 3111 and in the piping between the outflow valves 
2251 to 2256 and the reaction chamber 3111, if necessary. 
Needless to say, the kinds of gas and the valve operation described above 
may be changed according to conditions of formation of each layer. 
A heating member adapted to use in vacuum may be used as a means for 
heating the support, as in the case of the above-described RF-PCVD 
process. Alternatively, a special heating chamber other than the reaction 
chamber may be provided to heat the support, and the heated support may be 
transported into the reaction chamber while being maintained in a vacuum. 
In the .mu.W-PCVD process, the pressure in the discharge space is set, 
preferably, in the range of 1.times.10.sup.-3 to 1.times.10.sup.-1 Torr, 
more preferably, in the range of 3.times.10.sup.-3 to 5.times.10.sup.-2 
Torr, and most preferably, in the range of 5.times.10.sup.-3 to 
3.times.10.sup.-2 Torr. 
The pressure outside the discharge space may be set to any pressure lower 
than that in the discharge space. However, the effect of improving the 
properties of the deposited film is particularly high, if the pressure in 
the discharge space is three times the pressure outside the discharge 
space or higher when the pressure in the discharge space is 
1.times.10.sup.-1 Torr or lower, more particularly when it is 
5.times.10.sup.-2 Torr or lower. 
Microwaves are guided to the reactor, for example, by a method of using a 
waveguide, and are introduced into the reactor, for example, by a method 
of introduction through one or a plurality of dielectric windows. Such a 
microwave introducing window is ordinarily formed of a material of a small 
microwave loss, such as alumina (Al.sub.2 O.sub.3), aluminum nitride (AlN) 
, boron nitride (BN), silicon nitride (SiN), silicon carbide (SiC), 
silicon oxide (SiO.sub.2), berylium oxide (BeO), Teflon or polystyrene. 
The waveform and frequency of the voltage applied to the electrode are not 
particularly limited and the size and shape of the electrode may be 
selected freely as long as discharge is not disturbed. For practical use, 
it is preferable to form the electrode into the shape of a cylinder having 
a diameter in the range of 0.1 to 5 cm. Also, the length of the electrode 
may be set arbitrarily as long as an electric field is thereby applied 
uniformly to the support. 
The electrode may be formed of any material as long as it has an 
electroconductive surface. Ordinarily, the electrode is, for example, a 
member formed of a metal, such as stainless steel, Al, Cr, Mo, Au, In, Nb, 
Te, V, Ti, Pt, Pd or Fe, an alloy of these metals, or a glass, ceramic or 
plastic member having a processed electroconductive surface. 
FIG. 4 is a schematic cross-sectional view of an example of a-Si 
photosensitive members formed in the above-described manner. The 
illustrated photosensitive member has an electroconductive support 501 
formed of Al or the like, a charge injection obstruction layer 502 for 
obstructing injection of charge from the electroconductive support 501, 
which is formed if necessary, a layer 503 formed of an amorphous material 
containing at least silicon atoms and having a photoconductive property, 
and a surface layer 504 provided if necessary by being formed of a 
material containing silicon atoms and carbon atoms and, if necessary, 
hydrogen atoms and/or halogen atoms. The surface layer 504 has a function 
of retaining electric charge and/or a function of improving 
characteristics relating to external factors, such as wear resistance and 
moisture resistance. 
As described above, good electrophotographic photosensitive members have 
been manufactured by the electrophotographic photosensitive member 
manufacturing methods using RF-PCVD and .mu.W-PCVD processes. However, 
there is a need to provide an electrophotographic photosensitive member 
having further improved performance in order to meet various demands with 
respect to recent electrophotographic apparatuses, for example, for a 
further reduction in the size of the apparatus, an increase in the 
operating speed of the apparatus and an improvement in image quality. 
More specifically, when the size of an electrophotographic apparatus is 
reduced, a main charging device is also reduced in size with a reduction 
in the size of the apparatus. As a result, the corona current supplied to 
a photosensitive member is reduced. Therefore, it is necessary to achieve 
a further improvement in charging performance of the photosensitive member 
in order to obtain a required dark potential. 
With respect to realization of high speed image formation, an improvement 
in chargeability of a photosensitive member is inevitably required with a 
reduction in charging time. Further, the photo-response must also be 
improved since the time period taken to transport a photosensitive member 
after the formation of a latent image by irradiation of image exposure 
light to a development device for developing the latent image is reduced. 
With respect to improvements in image qualities, it is required that image 
defects such as spot defects appearing as black or white dots in an image 
should be reduced and that occurrence of ghosts or the like, i.e., a 
phenomenon of density unevenness caused in an image by a preceding-time 
latent image remaining as a photo-memory during image formation repeated a 
number of times, should be further reduced. 
SUMMARY OF THE INVENTION 
In view of these problems, an object of the present invention is to provide 
a manufacturing method whereby a good photosensitive member improved in 
potential characteristics such as chargeability and photo-response as well 
as in the effect of reducing photo-memory and defects which cause spot 
image defects can be stably manufactured with improved reproducibility. 
To achieve this object, according to the present invention, there is 
provided a method of manufacturing an amorphous silicon 
electrophotographic photosensitive member by a plasma CVD process using 
electromagnetic waves having a frequency of 13.56 MHz or higher as power 
for generating plasma, in which a film is formed on a base of the 
photosensitive member under conditions that the spatial potential of 
plasma generated by the electromagnetic waves with respect to the base is 
not higher than 120 V and the current density of ions incident upon the 
base is not lower than 0.4 mA/cm.sup.2.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The inventors of the present invention have conducted studies and have 
found that, in manufacturing an amorphous silicon electrophotographic 
photosensitive member, the spatial potential of plasma on a base and the 
current density of ions incident upon the base are important factors for 
improvements in the photosensitive member. The present invention has been 
achieved on the basis of this finding. 
That is, according to this finding, it is important that in a method of 
manufacturing an amorphous silicon electrophotographic photosensitive 
member by a plasma CVD process using at least electromagnetic waves having 
a frequency of 13.56 MHz or higher as power for generating plasma, the 
spatial potential of plasma generated by the electromagnetic waves with 
respect to a base and the current density of ions incident upon the base 
are set within predetermined ranges. 
More specifically, according to this finding, the above-mentioned objects 
of the invention can be effectively achieved by setting the spatial 
potential of plasma generated by electromagnetic waves with respect to a 
base to a potential not higher than 120 V and the current density of ions 
incident upon the base to a value not smaller than 0.4 mA/cm.sup.2 to form 
a film. 
That is, if the spatial potential and the ion current density are set 
within the above-mentioned ranges, the manufactured amorphous silicon 
photosensitive member is improved in potential characteristics such as 
chargeability, photo-response and residual potential while photo-memory 
and defects which cause spot image defects are reduced. 
This effect is particularly high 
(a) if electromagnetic waves in the microwave band, particularly 
electromagnetic waves having a frequency of 2.45 GHz, are used as power 
for generating plasma, 
(b) if a film having a thickness of 3 .mu.m or more is formed on the base 
under conditions that the spatial potential is not higher than 120 V and 
the incident ion current density is not lower than 0.4 mA/cm.sup.2, and 
(c) if ions of atoms in the group VII and/or the group VI in the periodic 
table are caused to exist in plasma, preferably, to an amount of 
1.times.10.sup.5 /cm.sup.3 or more and, more preferably, to an amount in 
the range of 1.times.10.sup.5 /cm.sup.3 to 1.times.10.sup.8 /cm.sup.3. 
This effect can be stably obtained with high reproducibility by increasing 
the current density of ions incident upon the base relative to that of 
ions incident upon places other than the base of the photosensitive 
member. 
The cause or mechanism of realizing this effect is not clear but it is 
thought with certainty that good film growth is promoted by ion 
irradiation supplying suitable energy to atoms contributing to film 
deposition on the base surface. 
As a means for supplying energy to atoms contributing to film deposition on 
the base surface, heating with a heater on the base surface may be 
performed. With respect to such a heating means, however, it is known that 
if the heating temperature is excessively high, the amount of hydrogen in 
the formed film is so reduced that dangling bond compensation is 
insufficient, resulting in a deterioration in film characteristics. In 
this case, the same energy supplying effect as that of ion irradiation 
cannot be obtained. 
Japanese Patent Laid-Open Publication No. 61-283116 discloses a method of 
manufacturing a good electrophotographic photosensitive member by placing 
a bias application electrode in plasma and by applying a bias to this 
electrode. This methods suggests that a photosensitive member 
characteristic can be improved by increasing the spatial potential of 
plasma. However, with respect to a further improvement in photosensitive 
member characteristics and, in particular, a sufficient improvement in the 
effect of reducing defects which cause spot image defects, the amount of 
improvement is not sufficiently increased if only a bias is applied. 
According to the present invention, the spatial potential of plasma is 
positively limited to a value not higher than 120 V, and the current 
density of ions incident upon the base, which has not specially been 
controlled as a particular parameter, is maintained at a value not smaller 
than 0.4 mA/cm.sup.2, whereby potential characteristics and photo-memory 
characteristics are improved while defects which cause spot image defects 
are reduced. The method of the present invention is particularly effective 
in reducing spot defects, the occurrence of which has been a considerable 
hindrance to the improvements in photosensitive member characteristics. 
The present invention will be described in detail with respect to various 
experimental examples. 
(Experimental Example 1) 
An RF-PCVD apparatus illustrated in FIG. 5 was used to make an experiment 
on controlling the spatial potential of plasma and the current density of 
ions incident upon a base. In FIG. 5 are illustrated a reaction chamber 
601, a cylindrical support 602, a support heating heater 603, raw material 
gas introducing pipes 604, first coils 605 for forming a magnetic field, 
and second coils 606 for forming a magnetic field. 
A magnetic field was formed in the reaction chamber 601 as schematically 
shown in FIG. 6 by controlling the currents through the first magnetic 
field forming coils and the second magnetic field forming coils. In this 
experiment, the maximum magnetic field strength in the cylindrical 
reaction chamber 601 could be controlled in the range of 0 to 2 kG. The 
current density of ions incident upon the base was measured at a center of 
the base, and the plasma potential was measured with a Langmuir probe 
inserted in plasma. 
FIG. 7 shows the relationship between the maximum magnetic field strength 
in the reaction chamber 601, the spatial potential of plasma and the 
current density of ions incident upon the base under the conditions of a 
first photoconductive layer shown in Table 1. In FIG. 7, the ion current 
density and the plasma spatial potential are shown in arbitrary units (a. 
u.). In the apparatus shown in FIG. 6, the current density of ions 
incident upon the base can be mainly controlled without changing the film 
formation conditions. 
(Experimental Example 2) 
A .mu.W-PCVD apparatus illustrated in FIG. 8 was used to make an experiment 
on controlling the spatial potential of plasma and the current density of 
ions incident upon a base. In FIG. 8 are illustrated a reaction chamber 
901, cylindrical supports 902, driving devices 903, support heating 
heaters 903, waveguides 905, microwave introducing windows 906, a 
discharge space 907, a gas introducing pipe 908, magnetic field forming 
coils 909, and a bias electrode 910. 
A mirror magnetic field was formed in the reaction chamber 901 as 
schematically shown in FIG. 9 by controlling the currents through the 
magnetic field forming coils 910. In this experiment, the maximum magnetic 
field strength in the cylindrical reaction chamber 901 could be controlled 
in the range of 0 to 1.5 kG. The current density of ions incident upon the 
base was measured at a center of the base, and the plasma potential was 
measured with a Langmuir probe inserted in plasma. 
FIG. 10 shows the relationship between the maximum magnetic field strength 
in the reaction chamber 901 and the current density of ions incident upon 
the base under the conditions of a first photoconductive layer shown in 
Table 2. The spatial potential of plasma was maintained always constantly 
by controlling the potential of the bias electrode 910. In FIG. 10, the 
ion current density is shown in an arbitrary unit (a. u.). 
FIG. 11 shows the relationship between the bias electrode potential and the 
plasma spatial potential under the conditions shown in Table 2. The 
current density of ions incident upon the base was maintained always 
constantly by controlling the coil current. 
From the results shown in FIGS. 10 and 11, it was understood that both the 
spatial potential of plasma and the current density of ions incident upon 
the base could be controlled in the apparatus of this experiment. 
(Experimental Example 3) 
A photosensitive member was manufactured under the conditions shown in 
Table 3 by using the apparatus used in Experimental Example 2, and the 
effects of the spatial potential of plasma and the current density of ions 
incident upon the base were examined. The time for forming film of each 
photoconductive layer was finely controlled so that the film thicknesses 
of the photosensitive member were equal with respect to all the 
conditions. 
FIGS. 12(a) through 12(c) show changes in the chargeability, the 
sensitivity and the number of spot defects of the photosensitive member 
measured when the spatial potential of plasma was changed. The 
chargeability is represented by the surface potential of the 
photosensitive member measured when the photosensitive member was charged 
with a constant current value by corona discharge in a dark condition. The 
sensitivity is represented by the quantity of light required to reduce the 
surface potential of the photosensitive member to 50 V by halogen light 
after setting the surface potential to 400 V in a dark condition. The 
number of spot defects is represented by the number of spherical 
protrusions of 10 .mu.m or greater existing in 9 cm.sup.2 on the 
photosensitive member surface counted by microscopic observation. The ion 
current densities i.sub.s in the measurements shown in FIGS. 12(a) to 
12(c) are 4 mA/cm.sup.2, 1.3 A/cm.sup.2 and 0.4 mA/cm.sup.2, respectively. 
FIGS. 13(a) through 13(c) show changes in the chargeability, the 
sensitivity and the number of spot defects of the photosensitive member 
measured when current density of ions incident upon the base was changed. 
The plasma potentials Vp in the measurements shown in FIGS. 3(a) to 13(c) 
are 120 V, 60 V and 20 V, respectively. 
From the results shown in FIGS. 12a through 12c and FIGS. 13a through 13c, 
the following is recognized. As the plasma spatial potential is increased, 
both the chargeability and the sensitivity are improved but the number of 
spot defects is steeply increased. On the other hand, with respect to the 
increase in the current density of ions incident upon the base, the 
chargeability and the sensitivity are improved when the ion current 
density is higher than 0.4 mA/cm.sup.2, while the number of spot defects 
is constant. This effect is particularly high when the plasma spatial 
potential is higher. Thus, in manufacturing a photosensitive member having 
improved chargeability and sensitivity and a smaller number of spot 
defects, setting the plasma spatial potential to a potential not higher 
than 120 V and the current density of ions incident upon the base to a 
value not smaller than 0.4 mA/cm.sup.2 is effective. 
(Experimental Example 4) 
An RF-PCVD apparatus illustrated in FIG. 14 was used to make an experiment 
on controlling the spatial potential of plasma and the current density of 
ions incident upon a base. In FIG. 14 are illustrated a reaction chamber 
1501, a cylindrical support 1502, a support heating heater 1503, raw 
material gas introducing pipes 1504, first coils 1505 for forming a 
magnetic field, second coils 1506 for forming a magnetic field, and a 
mesh-like bias electrode 1507. 
Changes in the spatial potential of plasma and the current density of ions 
incident upon the base were measured while the magnetic field strength was 
changed through the voltage applied to the mesh-like bias electrode 1507 
and the currents through the magnetic field forming coils. 
FIG. 15 shows the relationship between the maximum magnetic field strength 
in the reaction chamber and the current density of ions incident upon the 
base under the conditions of the first photoconductive layer shown in 
Table 2. The spatial potential of plasma was maintained always constantly 
by controlling the potential of the bias electrode 1507. 
FIG. 16 shows the relationship between the bias electrode potential and the 
plasma spatial potential under the conditions of the first photoconductive 
layer shown in Table 2. The current density of ions incident upon the base 
was maintained always constantly by controlling the coil current. 
From the results shown in FIGS. 15 and 16, it was understood that both the 
spatial potential of plasma and the current density of ions incident upon 
the base could be controlled in the apparatus of this experiment. 
(Experimental Example 5) 
A photosensitive member was manufactured under the conditions shown in 
Table 1 by using the apparatus used in Experimental Example 4, and the 
effects of the spatial potential of plasma and the current density of ions 
incident upon the base were examined. The time for forming film of each 
photoconductive layer was finely controlled so that the film thicknesses 
of the photosensitive member were equal with respect to all the 
conditions. 
FIGS. 17(a) through 17(c) show changes in the chargeability, the 
sensitivity and the number of spot defects of the photosensitive member 
measured when the spatial potential of plasma was changed. The 
chargeability is represented by the surface potential of the 
photosensitive member measured when the photosensitive member was charged 
with a constant current value by corona discharge in a dark condition. The 
sensitivity is represented by the quantity of light required to reduce the 
surface potential of the photosensitive member to 50 V by halogen light 
after setting the surface potential to 400 V in a dark condition. The 
number of spot defects is represented by the number of spherical 
protrusions of 10 .mu.m or greater existing in 9 cm.sup.2 on the 
photosensitive member surface counted by microscopic observation. The ion 
current densities i.sub.s in the measurements shown in FIGS. 17(a) to 
17(c) are 4 mA/cm.sup.2, 1.3 A/cm.sup.2 and 0.4 mA/cm.sup.2, respectively. 
FIGS. 18(a) through 18(c) show changes in the chargeability, the 
sensitivity and the number of spot defects of the photosensitive member 
measured when current density of ions incident upon the base was changed. 
The plasma potentials Vp in the measurements shown in FIGS. 18(a) to 18(c) 
are 120 V, 60 V and 20 V, respectively. 
As can be understood from FIGS. 17a through 17c and FIGS. 18a through 18c, 
the same results as those in Experimental Example 3 were obtained. It was 
thereby understood that, in manufacturing a photosensitive member having 
improved chargeability and sensitivity and a smaller number of spot 
defects, setting the plasma spatial potential to a potential not higher 
than 120 V and the current density of ions incident upon the base to a 
value not smaller than 0.4 mA/cm.sup.2 is effective. 
(Experimental Example 6) 
An a-SiC photosensitive member was manufactured by a process using the 
apparatus used in Experimental Example 3, in which, under the conditions 
of the second photoconductive layer shown in Table 3, CO.sub.2 was 
introduced, the amount of B.sub.2 H.sub.6 was finely controlled and the 
oxygen ion density in plasma was changed. FIGS. 19(a) through 19(c) and 
20(a) through 20(c) show changes in the chargeability, the sensitivity and 
the number of spot defects of the photosensitive member measured when the 
plasma spatial potential, the current density of ions incident upon the 
base and the oxygen ion density in plasma were changed. The chargeability, 
the sensitivity and the number of spot defects were evaluated in the same 
manner as Experimental Example 5. Also in this case, measurements were 
performed by setting the same values of the ion current density i.sub.s 
and the plasma spatial potential Vp as in the case of Experimental Example 
5. 
From the results of these measurements, it was understood that a 
particularly high effect could be obtained by setting the current density 
of ions incident upon the base to 0.4 mA/cm.sup.2 or higher and the oxygen 
ion density in plasma, preferably, to 1.times.10.sup.5 /cm.sup.3 and, more 
preferably, within the range of 1.times.10.sup.5 /cm.sup.3 to 
1.times.10.sup.8 /cm.sup.3. 
The same experiments were made with respect to ions of other atoms in the 
groups VI and VII in the periodic table. It was confirmed that the same 
effect can be achieved with respect to these ions. 
(Experimental Example 7) 
The apparatus used in Experimental Example 4 was remodeled and three 
auxiliary electrodes 2007 to 2009 provided as a first to third auxiliary 
electrodes, respectively, were placed as shown in FIG. 21. Photosensitive 
members were manufactured 100 times under the conditions shown in Table 1 
while setting the first and third auxiliary electrodes to the same 
potential and selecting and controlling the potential of the second 
auxiliary electrode so as to change the current density of ions incident 
upon the second electrode. The reproducibility of the photosensitive 
member was thereby examined. The plasma potential was set to 80 V and the 
current density of ions incident upon the case was set to 1 mA/cm.sup.2. 
The potential characteristics and the image characteristics of the 
manufactured photosensitive members were evaluated in the same manner as 
Experimental Example 5. 
FIGS. 22(a) through 22(c) show deviations of the chargeability, the 
sensitivity an the number of spot defects through 100 times. From these 
results, it was understood that the effect of the present invention can be 
obtained stably with improved reproducibility by increasing the current 
density of ions incident upon the base relative to that of ions incident 
upon places other than the base. 
Examples of the present invention will be described to further explain the 
invention. However, the present invention is not limited to the examples 
described below. 
(Example 1) 
An a-Si photosensitive member was manufactured by using the apparatus used 
in Experimental Example 4 under the conditions shown in Table 1. The 
plasma potential was set to 60 V and the current density of ions incident 
upon the base was set to 2 mA/cm.sup.2. Table 4 shows the results of 
measurements of the potential and image characteristics of the 
manufactured photosensitive member. A copying machine NP-5060 made by 
Canon Inc. was used to evaluate the image characteristics, and the 
potential characteristics were evaluated by setting a potential measuring 
jig in place of the development device in the machine NP-5060. 
For the evaluation, methods shown below were used with respect to 
evaluation items. 
Chargeability . . . The dark portion potential at a development device 
position is measured when a constant current is caused to flow through the 
main charging device of the copying machine. Accordingly, the 
chargeability is higher if the dark current potential is higher. 
Sensitivity . . . The sensitivity is evaluated by adjusting the main 
charging device current so that the dark portion potential at the 
development device position is set to a constant value, by using white 
paper having a reflection density of 0.01 or lower as an original and by 
measuring the image exposure light quantity adjusted so that the bright 
portion potential at the development device position is set to a 
predetermined value. Accordingly, the sensitivity is better if the image 
exposure light quantity is smaller. 
Combined potential characteristic . . . Four evaluation items, including 
potential non-uniformity and potential shifts as well as chargeability and 
sensitivity, are synthetically evaluated. Potential non-uniformity and 
potential shifts are evaluated by the following methods. 
Potential non-uniformity . . . Dark portion nonuniformity at the 
development device position when a constant current is caused to flow 
through the main charging device of the copying machine, and Bright 
portion non-uniformity at the development device position when white paper 
having a reflection density of 0.01 or lower is used as an original are 
measured and evaluated. 
Potential shifts . . . Continuous copying operation is performed by causing 
a constant current through the main charging device, and changes in the 
dark portion potential at the development device position are measured. 
Photo-memory . . . The current value of the main charging device is 
adjusted so that the dark portion potential at the development device 
position is set to a predetermined value, and the image exposure light 
quantity is thereafter adjusted so that the bright portion potential when 
predetermined white paper is used as an original is set to a predetermined 
value. In this state, a sheet prepared by attaching black circular marks 
having a reflection density of 1.1 and a diameter of 5 mm to a ghost chart 
made by Canon (part number: FY9-9040) is placed on the original table, and 
a half-tone chart made by Canon is superposed on this sheet. A copy image 
is formed in this manner. In the obtained copy image, the difference 
between the reflection density of the 5 mm diameter black circles of the 
ghost chart recognized on the half-tone copy and the reflection density of 
the half-tone portion is measured. 
Spot defects . . . Copying is performed without lighting the original 
illumination lamp of the copying machine, and the number of white dots 
having a diameter of 0.3 mm or larger in the obtained black copy image is 
counted. 
Combined image characteristic . . . The copied image is synthetically 
evaluated with respect to the characteristics including photo-memory and 
spot defects. 
Combined . . . The combined potential characteristic and the combined image 
characteristic are synthetically evaluated. 
The above-described evaluation uses ten ranks: an average evaluated value 
is set to rank 5, lower values are shown as lower ranks 4, 3, 2 and 1 in 
accordance with the inferiority degree, and higher levels are shown as 
higher ranks 6, 7, 8, and 10. 
In this example, as shown in Table 4, both the potential characteristics 
and the image characteristics were good. In particular, a very good result 
was obtained with respect to spot defects. Thus, the effect of the present 
invention was confirmed. 
(Comparative Example 1) 
An a-Si photosensitive member was manufactured in the same manner as 
Example t except that the current density of ions incident upon the base 
was set to 0.2 mA/cm.sup.2. Table 4 shows the results of measurements of 
the potential and image characteristics of the manufactured photosensitive 
member. The potential and image characteristics were evaluated in the same 
manner as Example 1. In comparison with Example 1, reductions in 
chargeability and sensitivity and an increase in photo-memory were 
recognized. 
Although substantially no influence of photo-memory was recognized at the 
time of copying a character original, the level of photo-memory at the 
time of copying an image original such as a photograph having many 
half-tone portions was so high that the influence was definitely 
recognizable. A definite difference was recognized from the photo-memory 
effect of Example 1 in which substantially no memory was recognized a the 
time of copying the same original. Also, with a reduction in sensitivity, 
a fog was caused when a character original on color paper was copied, and 
the resulting copied image was not sufficiently clear. 
(Example 2) 
An a-SiC photosensitive member was manufactured by using the apparatus used 
in Experimental Example 3 under the conditions shown in Table 3. The 
plasma potential was set to 120 V and the current density of ions incident 
upon the base was set to 2 mA/cm.sup.2. The results of measurements of the 
potential and image characteristics of the manufactured photosensitive 
member are shown in Table 4. The potential and image characteristics were 
evaluated in the same manner as Example 1. Both the potential 
characteristics and the image characteristics were very good. In 
particular, a very good result was obtained with respect to photo-memory 
and the effect of the present invention was confirmed. 
(Comparative Example 2) 
An a-SiC photosensitive member was manufactured in the same manner as 
Example 2 except that the current density of ions incident upon the base 
was set to 0.2 mA/cm.sup.2. The results of measurements of the potential 
and image characteristics of the manufactured photosensitive member are 
shown in Table 4. The potential and image characteristics were evaluated 
in the same manner as Example 1. In comparison with Example 1, a 
deterioration was recognized in every respect excepting spot defects. 
With a reduction in sensitivity, a fog was caused when a character original 
on color paper was copied, and the resulting copied image was not 
sufficiently clear. 
(Comparative Example 3) 
An a-SiC photosensitive member was manufactured in the same manner as 
Example 2 except that the plasma potential was set to 140 V. The results 
of measurements of the potential and image characteristics of the 
manufactured photosensitive member are shown in Table 4. The potential and 
image characteristics were evaluated in the same manner as Example 1. In 
comparison with Example 1, a deterioration was recognized with respect to 
spot defects. 
The number of spot defects having a diameter of 0.1 mm or less was 
particularly large, although the influence was practically negligible. 
However, when an image original was copied, a certain difference in image 
quality from Example 2 was recognized. 
(Example 3) 
An a-Si photosensitive member was manufactured by using the apparatus used 
in Experimental Example 5 under the conditions shown in Table 2. The 
plasma potential was set to 100 V and the current density of ions incident 
upon the base was set to 2 mA/cm.sup.2. The results of measurements of the 
potential and image characteristics of the manufactured photosensitive 
member are shown in Table 4. The potential and image characteristics were 
evaluated in the same manner as Example 1. Both the potential 
characteristics and the image characteristics were very good and the 
effect of the present invention was confirmed. 
(Comparative Example 4) 
An a-Si photosensitive member was manufactured in the same manner as 
Example 3 except that the current density of ions incident upon the base 
was set to 0.2 mA/cm.sup.2. The results of measurements of the potential 
and image characteristics of the manufactured photosensitive member are 
shown in Table 4. The potential and image characteristics were evaluated 
in the same manner as Example 1. In comparison with Example 3, a 
deterioration was recognized with respect to photo-memory. 
In particular, with a reduction in chargeability, the contaminated state of 
the main charging device after long-term copying was largely different 
from that of Example 3. A definite difference in maintenance performance 
from Example 3 was recognized. 
(Comparative Example 5) 
An a-Si photosensitive member was manufactured in the same manner as 
Example 3 except that the plasma potential was set to 140 V. The results 
of measurements of the potential and image characteristics of the 
manufactured photosensitive member are shown in Table 4. The potential and 
image characteristics were evaluated in the same manner as Example 1. In 
comparison with Example 3, a deterioration with respect to spot defects 
was considerable. 
The number of spot defects having a diameter of 0.1 mm or less was 
particularly large, although the influence was practically negligible. 
However, when an image original was copied, a certain difference in image 
quality from Example 3 was recognized. 
(Example 4) 
An a-Si photosensitive member was manufactured by using the apparatus used 
in Example 2 under the conditions shown in Table 2. The current density of 
ions incident upon the base was set to 2 mA/cm.sup.2 and the plasma 
potential was set to 100 V when a 3 .mu.m thick film was formed on the 
base and to 140 V under the other conditions. The results of measurements 
of the potential and image characteristics of the manufactured 
photosensitive member are shown in Table 4. The potential and image 
characteristics were evaluated in the same manner as Example 1. Both the 
potential characteristics and the image characteristics were very good and 
the effect of the present invention was confirmed. 
(Comparative Example 6) 
A photosensitive member was manufactured by using the same apparatus and 
same conditions as Example 4 except that the plasma potential was set to 
100 V when a 2 .mu.m thick film was formed on the base and to 140 V under 
the other conditions. The results of measurements of the potential and 
image characteristics of the manufactured photosensitive member are shown 
in Table 4. In comparison with Example 4, a considerable deterioration 
with respect to spot defects was recognized. 
The number of spot defects having a diameter of 0.1 mm or less was 
particularly large, although the influence was practically negligible. 
However, when an image original was copied, a certain difference in image 
quality from Example 4 was recognized. 
(Example 5) 
An a-SiC photosensitive member was manufactured by using the apparatus used 
in Example 2, introducing CO.sub.2 and setting the oxygen ion density in 
plasma to 1.times.10.sup.6 /cm.sup.3 under the conditions shown in Table 
3. The plasma potential was set to 100 V and the current density of ions 
incident upon the base was set to 2 mA/cm.sup.2. The results of 
measurements of the potential and image characteristics of the 
manufactured photosensitive member are shown in Table 4. The potential and 
image characteristics were evaluated in the same manner as Example 1. Both 
the potential characteristics and the image characteristics were very good 
and the effect of the present invention was confirmed. 
(Comparative Example 7) 
An a-SiC photosensitive member was manufactured in the same manner as 
Example 5 except that the current density of ions incident upon the base 
was set to 0.2 mA/cm.sup.2. The results of measurements of the potential 
and image characteristics of the manufactured photosensitive member are 
shown in Table 4. The potential and image characteristics were evaluated 
in the same manner as Example 1. In comparison with Example 1, 
deteriorations were recognized with respect to chargeability, sensitivity 
and photo-memory. 
In particular, with a reduction in chargeability, the contaminated state of 
the main charging device after long-term copying was largely different 
from that of Example 5. A definite difference in maintenance performance 
from Example 5 was recognized. 
With a reduction in sensitivity, a fog was caused when a character original 
on color paper was copied, and the resulting copied image was not 
sufficiently clear. 
(Example 6) 
An a-SiC photosensitive member was manufactured by using the apparatus used 
in Experimental Example 7 under the conditions shown in Table 3. The 
plasma potential was set to 80 V and the current density of ions incident 
upon the base was set to 1 mA/cm.sup.2. The current density of ions upon 
the first to third auxiliary electrodes was set to 0.5 mA/cm.sup.2. The 
results of measurements of the potential and image characteristics of the 
manufactured photosensitive member are shown in Table 4. The potential and 
image characteristics were evaluated in the same manner as Example 1. Both 
the potential characteristics and the image characteristics were good and 
no problems were found. 
TABLE 1 
__________________________________________________________________________ 
RF Internal 
Support 
Layer 
Name of Used gas/flow 
power 
pressure 
temper- 
thick- 
layer rate (sccm) 
(W) (Torr) 
ature (.degree.C.) 
ness (.mu.m) 
__________________________________________________________________________ 
Second photo- 
SiH.sub.4 
200 
ppm 
300 0.5 250 3 
conductive 
B.sub.2 H.sub.6 
1000 
layer (relative 
to SiH.sub.4) 
H.sub.2 
200 
First photo- 
SiH.sub.4 
500 500 0.5 250 20 
conductive 
H.sub.2 
300 
layer 
Surface layer 
SiH.sub.4 
10 300 0.5 250 0.5 
CH.sub.4 
750 
__________________________________________________________________________ 
TABLE 2 
__________________________________________________________________________ 
.mu.W 
Internal 
Support 
Layer 
Name of Used gas/flow 
power 
pressure 
temper- 
thick- 
layer rate (sccm) 
(W) (mTorr) 
ature (.degree.C.) 
ness (.mu.m) 
__________________________________________________________________________ 
Second photo- 
SiH.sub.4 
300 
ppm 
1000 
10 250 3 
conductive 
H.sub.2 
100 
layer B.sub.2 H.sub.6 
1000 
(relative 
to SiH.sub.4) 
First photo- 
SiH.sub.4 
250 
ppm 
1000 
10 250 25 
conductive 
B.sub.2 H.sub.6 
2 
layer (relative 
to SiH.sub.4) 
H.sub.2 
250 
Surface layer 
SiH.sub.4 
75 1000 
10 250 0.5 
CH.sub.4 
800 
__________________________________________________________________________ 
TABLE 3 
__________________________________________________________________________ 
.mu.W 
Internal 
Support 
Layer 
Name of Used gas/flow 
power 
pressure 
temper- 
thick- 
layer rate (sccm) 
(W) (mTorr) 
ature (.degree.C.) 
ness (.mu.m) 
__________________________________________________________________________ 
Second photo- 
SiH.sub.4 
300 
ppm 
1000 
10 250 17 
conductive 
CH.sub.4 
150 
layer B.sub.2 H.sub.6 
3 
(relative 
to SiH.sub.4) 
H.sub.2 
250 
First photo- 
SiH.sub.4 
250 
ppm 
1000 
10 250 3 
conductive 
B.sub.2 H.sub.6 
2 
layer (relative 
to SiH.sub.4) 
H.sub.2 
250 
Surface layer 
SiH.sub.4 
75 1000 
10 250 0.5 
CH.sub.4 
800 
__________________________________________________________________________ 
TABLE 4 
__________________________________________________________________________ 
Comb. Spot Comb. 
Vd Sensitivity 
pot. char. 
Memory 
Defects 
image char. 
Comb. 
__________________________________________________________________________ 
Example 1 
9 9 9 10 10 10 10 
Comp. 7 5 5 5 10 6 6 
Ex. 1 
Example 2 
9 9 9 10 9 10 10 
Comp. 7 5 5 7 9 8 7 
Ex. 2 
Comp. 9 9 9 10 7 9 9 
Ex. 3 
Example 3 
9 9 9 10 9 10 10 
Comp. 5 5 5 7 9 5 5 
Ex. 4 
Comp. 9 9 9 10 5 7 8 
Ex. 5 
Example 4 
9 9 9 10 9 10 10 
Comp. 9 9 9 10 6 8 9 
Ex. 6 
Example 5 
10 10 10 10 9 10 10 
Comp. 5 5 5 7 9 5 5 
Ex. 7 
Example 6 
10 10 10 10 10 10 10 
Worse .rarw..rarw..rarw..rarw..rarw. Average .fwdarw..fwdarw..fw 
darw..fwdarw..fwdarw. Better 
Ranks 1 2 3 4 5 6 7 8 9 10 
__________________________________________________________________________ 
Vd: chargeability 
Comb. pot. char.: combined potential characteristic 
Memory: Photomemory 
Comb. image char.: combined image characteristic 
According to the present invention, as described above, potential 
characteristics such as chargeability and photo-response and the effect of 
reducing photo-memory and defects which cause spot image defects can be 
simultaneously improved. Thus, the characteristics of photosensitive 
members can be improved and the proportion of non-defectives in a 
production process can also be improved. 
According to the present invention, in a method of manufacturing an 
amorphous silicon electrophotographic photosensitive member by a plasma 
CVD process, at least electromagnetic waves having a frequency of 13.56 
MHz or higher are used as power for generating plasma, and a film is 
formed under conditions that the spatial potential of plasma generated by 
the electromagnetic waves with respect to a base is not higher than 120 V 
and the current density of ions incident upon the base is not lower than 
0.4 mA/cm.sup.2, thereby improving the potential characteristics and 
reducing spot defects causing image defects and photomemory. 
This effect is particularly high if electromagnetic waves having a 
frequency of 2.45 GHz are used as power for generating plasma, if a film 
having a thickness of 3 .mu.m or more is formed on the base under 
conditions that the spatial potential is not higher than 120 V and the 
incident ion current density is not lower than 0.4 mA/cm.sup.2, and if 
ions of atoms in the group VII and/or the group VI in the periodic table 
are caused to exist in plasma, preferably, to an amount of 
1.times.10.sup.5 /cm.sup.3 or more and, more preferably, to an amount in 
the range of 1.times.10.sup.5 /cm.sup.3 to 1.times.10.sup.8 /cm.sup.3. 
This effect can be obtained stably with improved reproducibility by 
increasing the current density of ions incident upon the base relative to 
the current density of ions incident upon places other than the base. 
Further, it has been found that an unexpected effect shown below can also 
be achieved by the present invention. In a copying machine using an a-Si 
photosensitive member manufactured in accordance with the present 
invention, the wear of a cleaning blade of a cleaning section is small and 
the life of the cleaning blade can be extended by 1 to 20% in comparison 
with copying machines using a-Si photosensitive members manufactured by 
the conventional manufacturing methods. A similar result has also been 
recognized in the case of comparison using photosensitive members equal to 
each other in the number of spherical protrusions. This effect is thought 
to be due to some state change in the normal portion of the photosensitive 
medium surface.