Method for forming a deposited film from a gaseous silane compound heated on a substrate and introducing an active species therewith

A process for forming a deposited film which comprises introducing a linear, branched or cyclic gaseous silane compound represented by a general formula: EQU Si.sub.x H.sub.y X.sub.z wherein X stands for a halogen atom, x is an integer 3, 4, 5 or 6, and y+z=2x or 2x+2; into a film forming space for forming a deposited film on a substrate, activating said silane compound on the surface of the heated substrate to generate a precursor functioning as a raw material for forming the deposited film, generating an active species capable of an interaction with said precursor in a separate activating space, and introducing said active species into the film forming space to form a deposited film on said substrate.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a method suitable for forming a deposited 
film, particularly a functional film, and more particularly an amorphous 
or crystalline deposited film adapted for use in semiconductor devices, 
electrophotographic photosensitive devices, image reading line sensors, 
image pickup devices, photoelectric elements or the like. 
2. Related Background Art 
As an example, for formation an amorphous silicpn film, various methods 
have been tried methods such as vacuum deposition, plasma CVD, CVD, the 
reactive sputtering, ion plating, photochemical vapor deposition etc. 
Generally, the plasma CVD method has been widely used and industrialized. 
However, such deposited film of amorphous silicon still needs to be 
improved in their electrical and optical properties, fatigue 
characteristic due to repeated use, resistance to environmental 
conditions, productivity, and mass producibility including uniformity and 
reproducibility. 
The reaction process in the plasma CVD process commonly used up to now in 
the formation of an amorphous silicon film is considerably more complex in 
comparison with that of the conventional CVD process, and has not fully 
been analyzed. Also the deposited film formation involves various 
parameters such as the substrate temperature, flow rates and ratio of 
introduced gases, pressure during film deposition, high-frequency electric 
power, structure of electrodes, structure of reactor vessel, rate of gas 
discharge, method of plasma formation etc. of which adjusting a 
combination thereof often results in an unstable plasma or undesirable 
effects on the formed film. Besides, since each apparatus has its own 
specific parameters, it is difficult to generalize the production 
conditions. 
On the other hand, the plasma CVD method is presently considered best for 
forming an amorphous silicon film having electrical and optical properties 
for various applications. 
However, for certain applications requiring reproducible mass production of 
a large area with uniform thickness and quality, the plasma CVD method 
requires a significant investment in equipment. Use of such equipment is 
inevitably concerned with complex items of control, narrower tolerances 
and delicate adjustments. For this reason improvements on these points 
have been longed for. 
On the other hand, the conventional CVD process requires a high 
temperature, and is unable to produce a deposited film having 
substantially acceptable properties. 
In this manner, there has been desired a process for forming an amorphous 
silicon film with an inexpensive apparatus while maintaining substantially 
acceptable properties and uniformity. 
For avoiding such drawbacks of the plasma CVD process, there is already 
proposed a novel process of activating a material for film formation in a 
separate "activating space" to obtain an active species, and introducing 
said active species alone into a film forming space for effecting film 
formation. 
However, since such process generally employs a commercially available and 
relatively stable lower order silane compound such as SiF.sub.4 or 
Si.sub.2 F.sub.6 as the material for producing a precursor for film 
formation in the activating space, such process requires a relatively 
large excitation energy such as electrical energy obtained for example by 
microwave, high-frequency current or DC current, thermal energy obtained 
for example by resistor heating or high-frequency heating or optical 
energy. Consequently, in this process it is difficult to improve the 
efficiency of activation beyond a certain point, as well as requiring 
further improvements in terms of the amount of energy required and the 
efficiency of consumption of the raw material gas, in order to achieve 
mass production with a low cost in a simple apparatus. 
SUMMARY OF THE INVENTION 
In consideration of the foregoing, the object of the peesent invention is 
to provide a process for forming a deposited film, capable of 
significantly improving the consumption efficiency of the raw material gas 
and simplifying the film forming equipment by activating a raw material 
gas for film formation directly on a heated substrate to generate a 
precursor. 
The above-mentioned object can be achieved, according to the present 
invention, by a process of introducing a linear, branched or cyclic 
gaseous silane compound represented by a general formula: 
EQU Si.sub.x H.sub.y X.sub.z 
wherein X stands for a halogen atom, x is an integer 3, 4, 5 or 6, and 
y+z=2x or 2x+2; into a film forming space for forming a deposited film on 
a substrate, activating said silane compound on the surface of the heated 
substrate thereby generating a precursor functioning as a material for 
film formation, also generating an active species capable of an 
interaction with said precursor in a separate activating space, and 
introducing said active species into the film forming space to formed a 
deposition film on said substrate.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Due to the absence of plasma in the film forming space for forming a 
desired deposition film, the film forming parameters of the process of the 
present invention are limited to the amounts of the introduced raw 
material gases for forming a deposited film and the active species, 
substrate temperature and pressure in the film forming space. 
Consequently, the cohtrol of the conditions for film formation becomes 
easier, and the deposited film can be mass produced in reproducible 
manner. 
In the present invention, the term of "precursor" means a substance capable 
of functioning as a raw material of the film to be formed. On the other 
hand, the term of "active species" means a substance capable of causing a 
chemical interaction with said precursor, thereby giving energy to the 
precursor or chemically reacting therewith, to render the precursor 
capable of more effectively forming the deposited film. Consequently, the 
active species may or may not contain a component constituting the film to 
be deposited. 
In the present invention, the active species introduced from the activating 
space A into the film forming space has a life 10 seconds or less, 
preferably 5 seconds or less, and most preferably 2 seconds or less. At 
the formation of deposited film in the film forming space, said active 
species interacts chemically with said precursor containing a component 
which becomes a principal constitutent of the film to be deposited. Thus, 
a desired film can be easily deposited on a desired substrate. 
Since the deposited film obtained according to the process of the present 
invention is formed without using plasma in the film forming space, the 
deposited film is substantially free from the undesirable influence of 
etching or abnormal discharge. Also the present invention can provide a 
more stable CVD process through the control of the temperature of the 
atmosphere in the film forming space and the substrate temperature. 
The process of the present invention is different from the conventional CVD 
process in that it employs a linear, branched or cyclic gaseous silane 
compound which can be activated at a low temperature and which is 
represented by a general formula Si.sub.x H.sub.y X.sub.2 wherein X is a 
halogen atom, x is an integer 3, 4, 5 or 6, and y+z=2x or 2x+2, to 
generate a precursor functioning as a raw material for the film to be 
formed on the surface of a substrate. An active species capable of a 
chemical interaction with said precursor is generated in a space separate 
from the film forming space and is introduced into the film forming space 
to interact with the precursor to form a deposited film on the substrate. 
In this manner, it is rendered possible to obtain a deposited film of a 
higher quality than that in the conventional CVD process, with a 
significantly higher deposition speed and at a lower substrate 
temperature. Thus, a deposited film of a stable quality can be obtained in 
industrial quantity with a lower cost. 
The halogen atom contained in the silane compound Si.sub.x H.sub.y X.sub.z 
employed in the present invention can be F, Cl, Br or I, preferably F or 
Cl. 
The number y of the hydrogen atoms contained in the silane compound 
Si.sub.x H.sub.y X.sub.z employed in the present invention is suitably 
determined by the number x of the silicon atoms constituting said silane 
compound. It is preferably in a range of 0.ltoreq.y.ltoreq.2x-2 if y+z=2x, 
or 0.ltoreq.y.ltoreq.2x if y+z=2x+2, and most preferably in a range of 
0.ltoreq.y.ltoreq.2x-4 if y+z=2x, or 0.ltoreq.y.ltoreq.2x-2 if y+z=2x+2. 
In a silane compound (Si.sub.x H.sub.y X.sub.z), the Si-Si dissociation 
energy becomes lower as the molecular structure becomes longer while the 
Si-halogen bonding energy is higher, particularly for F or Cl. 
Consequently, said silane compound Si.sub.x H.sub.y X.sub.z can be 
decomposed at lower temperature than that in silane compounds such as 
SiH.sub.4, SiF.sub.4, Si.sub.2 H.sub.6 or Si.sub.2 F.sub.6 and generates 
therefore radicals such as :SiHX constituting a precursor for forming an 
amorphous silicon film of a high quality. 
The silane compounds Si.sub.x H.sub.y X.sub.z employed in the present 
invention have to be activated on the surface of the heated substrate, and 
the substrate temperature is preferably in a range from 50.degree. to 
700.degree. C., more preferably from 80.degree. to 500.degree. C., and 
most preferably from 100.degree. to 350.degree. C., in order to prevent 
thermal deterioration or thermal deformation of the substrate and to 
obtain amorphous silicon film of satisfactory quality. 
The silane compounds Si.sub.x H.sub.y X.sub.z employed in the present 
invention are activated only on the surface of the heated substrate. 
Consequently, a local formation of the deposited film is possible by 
locally heating the substrate where the deposited film is required. Also, 
even if the substrate has a very large area, a deposited film of uniform 
quality can be obtained by heating entirely the substrate. 
Representative silicon skeleton structures of the silane compounds Si.sub.x 
H.sub.y X.sub.z advantageously employed n the present invention are shown 
in the following: 
##STR1## 
Examples of the material that can be introduced into the activating space A 
for generating the active species in the present invention are H.sub.2, 
SiH.sub.4, SiH.sub.3 F, SiH.sub.3 Cl, SiH.sub.3 Br, SiH.sub.3 I, and a 
rare gas such as He or Ar. 
In the present invention, the active species is generated in the activating 
space A by means of a suitable activation energy, such as an electrical 
energy with a microwave, a high-frequency current, a low-frequency current 
or a DC current, a thermal energy by a heater or an infrared heating, or a 
light energy, taking various conditions and apparatuses in consideration. 
In case there are employed plural gasses for film formation, they can be 
introduced into the activating space either as a premixture or 
independently from separate feeding sources. 
In the present invention, a catalyst may be employed in addition to the 
above-mentioned activation energy. 
Examples of such catalyst are preferably transition metals, non-transition 
metals, alloys thereof, and oxides thereof. 
More specifically, there can be employed Ti, Nb, Cr, Mo, W, Fe, Ni, Co, Rh, 
Pd, Mn, Ag, Zn, Cd, Na, K, Li, Pd-Ag, Ni-Cr, TiO.sub.2, NiO, V.sub.2 
O.sub.5, and the like. 
For activation, said catalyst may be directly heated by resistance heating 
through a current supply to said catalyst, or indirectly heated with an 
electric furnace or an infrared furnace incorporating a quartz tube filled 
with said catalyst. 
Said catalyst can be formed as granules, or fine metallic particles 
deposited on an inorganic porous carrier, a filament, a mesh, a tube or a 
honeycomb, and one of such forms can be suitably selected to control the 
cross section of generating the active species, thereby controlling the 
reaction between the precursor and the active species and achieving the 
formation of a uniform deposited film. 
In the following, the present invention will be clarified further by a 
representative example of the formation of an electrophotographic image 
forming member according to the process of the present invention. FIG. 1 
schematically shows the structure of a representative photoconductive 
member obtainable with the process of the present invention. 
The photoconductive member 10 shown in FIG. 1, applicable as an 
electrophotographic image forming member, has a layer structure comprising 
a substrate 11, an eventual intermediate layer 12, and a photosensitive 
layer 13. 
The substrate 11 can be electroconductive or electrically insulating. A 
conductive substrate can be composed of a metal such as NiCr, stainless 
steel, Al, Cr, Mo, Au, Ir, Nb, Ta, V, Ti, Pt or Pd, or an alloy thereof. 
An insulating substrate can be composed of a plastic film or sheet 
composed, for example, of polyester, polyethylene, polycarbonate, 
cellulose acetate, polypropylene, polyvinyl chloride, polyvinylidene 
chloride, polystyrene or polyamide, glass, ceramics or paper. Such 
insulating substrate is preferably rendered electroconductive at least one 
surface thereof, and is desirably provided with other layers on said 
conductive surface. 
For example, a glass substrate is rendered surfacially conductive by 
forming, on a surface thereof, a thin layer of NiCr, Al, Cr, Mo, Au, Ir, 
Nb, Ta, V, Ti, Pt, Pd, In.sub.2 O.sub.3, SnO.sub.2, ITO (In.sub.2 O.sub.3 
+SnO.sub.2) or the like. Also a plastic film such as a polyester film is 
rendered surfacially conductive by vacuum deposition, electron beam 
deposition, sputtering or lamination with a metal such as NiCr, Al, Ag, 
Pb, Zn, Ni, Au, Cr, Mo, Ir, Nb, Ta, V, Ti or Pt. Said substrate can be 
arbitrarily formed as a cylinder, a belt or a plate according to the 
application. It is preferably formed as an endless belt or a cylinder if 
the photoconductive member 10 shown in FIG. 1 is used as an 
electrophotographic image forming member for continuous high-speed 
copying. 
The intermediate layer 12 has a function of effectively preventing the 
entry of carriers from the substrate 11 to the photosensitive layer 13, 
and allowing easily the movement of photocarriers, generated in the 
photosensitive layer 13 by irradiation with an electromagnetic wave, from 
said layer 13 into the substrate 11. 
Said intermediate layer 12 is composed of amorphous silicon containing 
hydrogen atoms (H) and/or halogen atoms (X), represented as A-Si(H, X), 
and further contains, as a material for regulating the 
electroconductivity, a p-type impurity such as boron (B) or an n-type 
impurity such as phosphor (P). 
In the present invention, the amount of such conductivity regulating 
material such as B or P in the intermediate layer 12 is preferably in a 
range of 0.001-5.times.10.sup.4 atomic ppm, more preferably 
0.5-1.times.10.sup.4 atomic ppm, and most preferably 1-5.times.10.sup.3 
atomic ppm. 
The formation of the intermediate layer 12 can be continuously followed by 
the formation of the photosensitive layer 13. In such case, a silane 
compound Si.sub.x H.sub.y X.sub.z gas for forming the intermediate layer 
is introduced, eventually mixed with a diluting gas such as He or Ar with 
a predetermined ratio, into the film forming space containing a heated 
substrate 11 to generate the precursor on the surface thereof. Also into 
the activating space A, there is introduced a hydrogen-containing gas, 
eventually together with a compound containing an impurity element, to 
generate an active species eventually under the influence of catalyst, and 
said active species is introduced into the film forming spac to form the 
intermediate layer 12 on said substrate 11. 
Examples of the effective starting material to be introduced into the 
activating space A for generating the active species for forming the 
intermediate layer 12 include H.sub.2 ; Si-H compounds such as SiH.sub.4 ; 
hydrogen-rich halosilanes such as SiH.sub.3 Cl, SiH.sub.3 F or SiH.sub.3 
Br; gaseous or gasifiable nitrogen compounds, nitrides and azides 
containing N atoms or N and H atoms such as nitrogen (N.sub.2), ammonia 
(NH.sub.3), hydrazine (H.sub.2 NNH.sub.2), hydrogen azide (HN.sub.3) or 
ammonium azide (NH.sub.4 N.sub.3): hydrocarbons containing C and H atoms, 
for example, saturated hydrocarbons having 1-5 carbon atoms such as 
methane (CH.sub.4), ethane (C.sub.2 H.sub.6), propane (C.sub.3 H.sub.8), 
n-butane (n-C.sub.4 H.sub.10) or pentane (C.sub.5 H.sub.12); ethylenic 
hydrocarbons having 2-5 carbon atoms such as ethylene (C.sub.2 H.sub.4), 
propylene (C.sub.3 H.sub.6), 1-butene (C.sub.4 H.sub.8), 2-butene (C.sub.4 
H.sub.8), isobutylene (C.sub.4 H.sub.8) or pentene (C.sub.5 H.sub.10); 
acetylenic hydrocarbons having 2-4 carbon atoms such as acetylene 
(C.sub.2 H.sub.2), methylacetylene (C.sub.3 H.sub.4) or butyne (C.sub.4 
H.sub.6): oxygen (O.sub.2); ozone (O.sub.3); carbon monoxide (CO); carbon 
dioxide (CO.sub.2); nitrogen monoxide (NO); nitrogen dioxide (NO.sub.2); 
dinitrogen monoxide (N.sub.2 O); and the like. 
Such starting material for forming the intermediate layer 12 is suitably 
selected at the layer formation in such a manner that desired atoms are 
included as constituents in the intermediate layer 12. 
The thickness of the intermediate layer 12 is preferably in a range of 30 
to 1000 .ANG., more preferably 50 to 600 .ANG.. 
The photosensitive layer 13 is composed, for exhibiting photoconductivity 
suitable for an electrophotographic image forming member, of amorphous 
silicon A-Si(H, X) which is composed of silicon atoms as matrix and 
contains halogen atoms (X) eventually combined with hydrogen atoms (H). 
Also in forming the photosensitive layer 13, a silane compound Si.sub.x 
H.sub.y X.sub.z is introduced into the film forming space containing the 
heated substrate 11 and is excited and decomposed on the surface thereof 
to generate a precursor, in the same manner as in the formation of the 
intermediate layer 12. On the other hand, a starting gas such as H.sub.2, 
SiH.sub.4 or SiH.sub.3 F is introduced into the activating space A and 
generates an active species, eventually under the function of a catalyst. 
Said active species is introduced into the film forming space and causes a 
chemical interaction with the precursor generated on the surface of the 
substrate, thereby depositing a desired photosensitive layer 13. The 
thickness thereof is suitably determined according to the purpose of use. 
The thickness of the photosensitive layer 13 shown in FIG. 1 is suitably 
determined in relation to the thickness of the intermediate layer 12 in 
such a manner that said both layers 12 and 13 respectively function 
effectively, and is usually several hundred to several thousand times 
larger than that of the intermediate layer 12. 
More specifically said thickness is preferably in a range of 1 to 100.mu., 
more preferably 2 to 50.mu.. 
In the photoconductive layer shown in FIG. 1, the amount of H or X (halogen 
atoms such as F) contained therein is preferably in a range of 1 to 40 
atomic %, more preferably 5 to 30 atomic %. 
The photoconductive member shown in FIG. 1 may be eventually provided, on 
the photosensitive layer 13, with a surface layer. Said surface layer can 
be composed, for example, of silicon carbide and can be formed by 
introducing suitable gasses such as SiH.sub.4, CH.sub.4 and H.sub.2 or 
SiH.sub.4 and SiH.sub.2 (CH.sub.3).sub.2 into the activating space A to 
generate an active species with an excitation energy eventually combined 
with a catalyst and introducing said active species into the film forming 
space Said surface layer is preferably provided with a wide band gap, such 
as in a silicon nitride layer or a silicon oxide layer, and the film 
composition may be continuously changed from the photosensitive layer 13 
to the surface layer. Such surface layer, if present, is preferably 
provided with a thickness of 0.01 to 5.mu., more preferably 0.05 to 1.mu.. 
The deposited films formed by the process of the present invention can be 
doped with impurity elements during or after the film formation. Examples 
of p-type dopant are elements in the group IIIA of the periodic table such 
as B, Al, Ga, In or Tl, while those of n-type dopant are elements in the 
group VA such as N, P, As, Sb or Bi, and particularly preferred ones are 
P, Sb, As, and the like. 
For starting material for introducing such impurity, a materials are 
employed which are gaseous under normal temperature and pressure or are 
easily gasifiable at least under the film forming conditions. Specific 
examples of materials employable for the introduction of the impurity are 
PH.sub.3, P.sub.2 H.sub.4, PF.sub.3, PF.sub.5, PCl.sub.3, AsH.sub.3, 
AsF.sub.3, AsF.sub.5, AsCl.sub.3, SbH.sub.3, SbF.sub.5, BiH.sub.3, 
BF.sub.3, BCl.sub.3, BBr.sub.3, B.sub.2 H.sub.6, B.sub.4 H.sub.10, B.sub.5 
H.sub.9, B.sub.5 H.sub.10, B.sub.6 H.sub.10, B.sub.6 H.sub.12, AlCl.sub.3, 
and the like. 
Such impurity material may be activated either in the activating space A 
together with the material for generating the active species, or in 
another activating space B. 
EXAMPLE 1 
A-Si(H, X) deposited films of i-, p-, and n-type were prepared in the 
following operations by means of an apparatus shown in FIG. 3. 
In FIG. 3, a film forming chamber 101 is provided therein with a substrate 
support 102, for supporting a desired substrate 103. 
A substrate heater 104, for heating the substrate 103 prior to the film 
formation or annealing the formed film for improving the characteristics 
thereof, is powered through a cable 105. 
Gas sources 106-109 are provided according to the species of the film 
forming gas, eventually employed inert gas, and impurity-containing gas. 
Suitable gasifiers are provided if said gasses are liquid in the normal 
conditions. 
In said gas sources 106-109, there are provided branch tubes a flow meters 
b, pressure gauges c for measuring the pressure at the high-pressure side 
of said flow meters, and valves d and e for regulating flow rate. An 
activating chamber A 123 is provided for generating the active species. A 
tungsten catalyst 125 formed into a honeycomb structure is heated by a 
current supplied through wires 122. The raw material for generating the 
active species, supplied through a gas inlet pipe 110, is activated in the 
activating chamber A under the function of the heated catalyst, and the 
resulting active species is introduced into the film forming chamber 101 
through a pipe 124. There are also provided a gas pressure gauge 111, a 
discharge valve 120, and a discharge pipe 121. 
At first, a substrate 103 of "Corning 7059" (produced by Corning Comp.) was 
placed on the support 102, and the film forming chamber 101 was evacuated 
to ca. 10.sup.-6 Torr with a vacuum pump. Then, a current was supplied 
through the cable 105 to heat the substrate 103 to a surface temperature 
of 300.degree. C. 
Then, the tungsten catalyst 125 of honeycomb form, placed in the activating 
chamber 125, was heated to red-hot state by an electric current supplied 
through the wires 122. Then, 50 SCCM of H.sub.2 gas, or together with 40 
SCCM of PH.sub.3 or B.sub.2 H.sub.6, diluted to 1000 ppm with hydrogen, 
was introduced from a gas container 106 into the activating chamber A 123 
through the pipe 110. The hydrogen and other gases introduced into said 
chamber A 123 were activated with the tungsten catalyst in red-hot state 
to give active hydrogen etc. and introduced into the film forming chamber 
101 through the pipe 124. 
On the other hand, a silane compound Si.sub.4 F.sub.10 was introduced from 
an unrepresented container, through a pipe 115, to generate a precursor 
SiF.sub.2 * on the surface of the substrate heated to 300.degree. C. Said 
SiF.sub.2 * and the active hydrogen immediately caused chemical 
interaction to form a non-doped or doped A-Si(H, X) film of 700 .ANG. 
thickness on the surface of the substrate, with a rate of 35 .ANG./sec. 
The pressure in the film forming chamber was maintained at 0.7 Torr. 
The specimen with thus obtained non-doped or p-type A-Si(H, X) film was 
placed in a deposition chamber, and comb-shaped aluminum gap electrodes 
(gap length 250.mu., width 5 mm) were formed under a pressure of 10.sup.-5 
Torr. The properties of obtained films were evaluated by measuring the 
dark current at an applied voltage of 10 V and determining the dark 
conductivity .sigma.d with a microamperemeter (YHP 4140 B manufactured by 
YOKOKAWA HEWLETT-KARD Company). The film thickness was measured with a 
layer thickness measuring apparatus of Alpha-Step (manufactured by TENCOR 
Comp.) The results are summarized in Table 1. 
EXAMPLE 2 
A-Si(H, X) films were prepared in the same procedure as in the Example 1, 
except that the silane compound Si.sub.4 F.sub.10 was replaced by a silane 
compound Si.sub.5 H.sub.2 F.sub.10. Obtained results on the measured dark 
conductivity are summarized in Table 1. The film thickness and .delta.d 
were measured in the same manner as used in Example 1. Table 1 indicates 
that the process of the prevent invention can provide an A-Si(H, X) film 
of excellent electrical properties and such film with sufficient doping. 
TABLE 1 
______________________________________ 
Example 1 
Example 2 
______________________________________ 
Silane compound Si.sub.4 F.sub.10 
Si.sub.5 H.sub.2 F.sub.10 
Substrate temp. 300.degree. C. 
300.degree. C. 
Gas for active species 
H.sub.2 H.sub.2 
Catalyst W W 
.sigma.d (non-doped) (.OMEGA.cm).sup.-1 
5.0 .times. 10.sup.-10 
3.1 .times. 10.sup.-10 
.sigma.d (B-doped) (.OMEGA.cm).sup.-1 
5.2 .times. 10.sup.-9 
2.8 .times. 10.sup.-9 
.sigma.d (P-doped) (.OMEGA.cm).sup.-1 
7.1 .times. 10.sup.-8 
6.9 .times. 10.sup.-8 
______________________________________ 
EXAMPLE 3 
A drum-shaped electrophotographic image forming member of a layer structure 
as shown in FIG. 1 was prepared in the following manner, with an apparatus 
shown in FIG. 4. 
In FIG. 4, there are shown a film forming chamber 201, a silane compound 
introducing pipe 206, a motor 207, a heater 208 similar the heater 104 
shown in FIG. 3, blow pipes 209 and 210, a cylindrical aluminum substrate 
211, a discharge valve 212, gas sources 213-216 similar to those 106-109 
shown in FIG. 3, and a gas inlet pipe 217-1. 
The cylindrical aluminum substrate 211 was suspended in the film forming 
chamber 201, heated to 250.degree. C. by the heater 208 provided therein 
and rotated by the motor 207. 
A silane compound Si.sub.5 F.sub.12 was introduced from an unrepresented 
container, through a pipe 206, into the film forming chamber 201, and 
activated on the surface of the heated substrate whereby the substrate was 
covered with the precursor SiF.sub.2 *. 
On the other hand, a tungsten catalyst 222 of honeycomb form, placed in the 
activating chamber A, was heated to a red-hot state by a current supplied 
through wires 221. Then, H.sub.2 gas was introduced, through the pipe 
217-1, into the activating chamber A 220 and transformed into active 
hydrogen by the function of the catalyst, and the active hydrogen was 
introduced into the film forming chamber 201 through an inlet pipe 217-2. 
Simultaneously, an impurity gas such as PH.sub.3 or B.sub.2 H.sub.6 was 
introduced into the activating chamber A 220 and activated if necessary. 
The cylindrical aluminum substrate 211 was rotated, and the exhaust gas was 
discharged by suitably regulating the aperture of the discharge valve 212. 
The photosensitive layer 13 was prepared in this manner. 
Also the intermediate layer 12 was prepared with a thickness of 2000 .ANG., 
by introducing a gaseous mixture H.sub.2 /B.sub.2 H.sub.6, containing 
B.sub.2 H.sub.6 in 0.2 vol. %, through the inlet pipe 217-1. 
The film thickness and performances of the thus prepared member were 
measured in the same manner as used in Example 1. 
REFERENCE EXAMPLE 1 
An electrophotographic image forming member of a structure shown in FIG. 1 
was prepared with SiF.sub.4, H.sub.2, and B.sub.2 H.sub.6 through an 
ordinary plasma CVD process, in a film forming chamber which is similar to 
the chamber 201 except that it is provided with a high-frequency generator 
of 13.56 MHz. 
The film thickness and performances of the thus prepared member were 
measured in the same manner as used in Example 1. 
Table 2 summarizes the manufacturing conditions and performances of the 
electrophotographic image forming drums obtained in the Example 3 and the 
Reference Example 1. 
TABLE 2 
______________________________________ 
Example 3 
Ref. Example 1 
______________________________________ 
Gas for precursor 
Si.sub.5 F.sub.12 
-- 
Substrate temp. 250.degree. C. 
-- 
Main active species 
SiF.sub.2 * 
-- 
Amount introduced 
100 SCCM -- 
into film forming 
chamber 
Gas for active species 
H.sub.2 -- 
Catalyst W -- 
Amount from active. 
40 SCCM -- 
cham. A 
Amounts from containers 
-- SiF.sub.4 200 SCCM 
-- B.sub.2 H.sub.6 100 SCCM 
-- H.sub.2 100 SCCM 
Pressure in film 
0.9 Torr 1.00 Torr 
forming chamber 
Film forming rate 
20 .ANG./sec 
6 .ANG./sec 
Discharge power -- 1.8 W/cm.sup.2 
Thickness of photoses. 
22.mu. 22.mu. 
layer 13 
Average number of 
3 14 
defects in 10 drums 
Potential fluctuation 
in circumferential 
.+-.11 V .+-.28 V 
direc. 
in axial direction 
.+-.17 V .+-.32 V 
Note Process of Conventional CVD 
this substrate 
invention temperature 250.degree. C. 
______________________________________ 
EXAMPLE 4 
A PIN diode shown in FIG. 2 was prepared with the apparatus shown in FIG. 
3. 
At first a polyethylene terephthalate film 21, bearing a deposited ITO film 
22 of 1000 .ANG., was placed on the support, and the chamber was evacuated 
to 10.sup.-6 Torr. Then, in the same manner as in the Example 1, Si.sub.4 
H.sub.2 F.sub.8 was introduced through the inlet pipe 116, and H.sub.2 and 
PH.sub.3 gases, diluted to 1000 ppm with hydrogen gas, were introduced 
through the inlet pipe 110, into the activating chamber A 123, and 
activated in the presence of a tungsten catalyst. Subsequently, thus 
activated gasses were introduced, through the inlet pipe 124, into the 
film forming chamber 101, and an n-type A-Si(H, X) film 24 doped with P of 
700 .ANG. thickness was formed at an internal pressure of 0.4 Torr in said 
film forming chamber 101. 
Then, an i-type A-Si film 25 of 5000 .ANG. thickness was prepared in the 
same procedure except that PH.sub.3 gas was replaced by B.sub.2 H.sub.6 
gas diluted to 1000 ppm with hydrogen as. 
Subsequently, a p-type A-Si(H, X) film 26 doped with B of 700 .ANG. 
thickness was prepared in the same conditions as for the i-type film, 
except that diborane gas B.sub.2 H.sub.6, diluted to 1000 ppm with 
hydrogen, was introduced together with H.sub.2 gas. Then, an aluminum 
electrode 27 of 1000 .ANG. thickness was formed by vacuum deposition on 
said p-type film to obtain the PIN diode. 
The diode thus obtained (area 1 cm.sup.2) was subjected to the measurement 
of I-V characteristic to evaluate the rectifying and photovoltaic 
performances. The obtained results are summarized in Table 3. 
Also light irradiation characteristic was measured by introducing light 
through the substrate, and, at a light intensity of ca. 100 mW/cm.sup.2, 
there were obtained a conversion efficiency of 8.6% or higher, an open-end 
voltage of 0.94 V, and a shortcircuit current of 11 mA/cm.sup.2. 
The film thickness was measured in the same manner as used in Example 1. 
EXAMPLE 5 
A PIN diode was prepared in the same manner as in the Example 4, except 
that Si.sub.6 H.sub.2 F.sub.12 gas was introduced from the inlet pipe 115 
instead of Si.sub.4 H.sub.2 F.sub.8 gas. Rectifying characteristic and 
photovoltaic property measured on this sample are shown in Table 3. 
The film thickness was measured in the same manner as used in Example 1. 
TABLE 3 
______________________________________ 
Example 4 Example 5 
______________________________________ 
Silane for film forming 
Si.sub.4 H.sub.2 F.sub.8 
Si.sub.5 H.sub.2 F.sub.12 
Substrate temp. 260.degree. C. 
240.degree. C. 
Rectify. ratio of 
8.0 .times. 10.sup.2 
6.3 .times. 10.sup.2 
diode (*1) 
n value of diode (*2) 
1.2 1.3 
______________________________________ 
(*1) Ratio of forward current to reverse current at 1 Vol. 
(*2) n value (quality factor in a current equation of a pn junction 
##STR2## 
Table 3 indicates that the present invention can provide a PIN diode of 
A-Si(H, X) films with optical and electrical properties superior to those 
obtainable with the conventional technology. 
The film depositing process of the present invention can improve the 
electrical, optical, photoconductive, and mechanical properties of the 
deposited film, and is also capable of high-speed film forming without 
maintaining the substrate at a high temperature. Besides, it improves the 
reproducibility in film forming and the film quality, enables one to 
obtain uniform film quality, is suitable for forming a film of a large 
area, allows one to easily achieve mass production and to improve the film 
productivity. Also, since the precursor is generated by direct activation 
on the substrate, it is not necessary to employ separately an activation 
chamber for generating the precursor and it is made possible to save 
energy and to improve the efficiency of activation. Consequently, the 
consumption of the raw material gasses is significantly economized, and 
the film forming process is also simplified, so that a mass production 
with a low cost is rendered possible.