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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a deposited film forming method for
continuously forming deposited film on a long-size substrate by plasma CVD
method, and a deposited film forming apparatus therefor, and particularly
to a deposited film forming method and a deposited film forming apparatus
for forming deposited film having a composition distribution provided in a
direction of film thickness.
2. Related Background Art
In recent years, the demand for the electric power has been increasing
worldwide, so that the production of the electric power has been more
active, but with the growth of production, problems associated with
thermal power generation or atomic power generation such as environmental
pollution or global warming have appeared. In these situations, the solar
cell generation utilizing the sun rays has been noted because it does not
cause any problems such as environmental pollution or global warming, with
fairer distribution of the resource of the solar rays, and it can meet the
demand for the electric power which will further increase in the future.
To put solar cell electrical generation to practical use, it is required
that the solar cell has a sufficiently high photoelectric conversion
efficiency, as well as excellent characteristics and stability, and is
suitable for mass production. Due larger electrical scale generation, a
larger solar cell will be required. For these reasons, an amorphous
silicon type solar cell has been proposed in which a semiconductor thin
film made of an amorphous silicon is deposited on a substrate made of a
glass or metallic sheet which is relatively cheap by decomposing a readily
available source gas such as silane by glow discharge. This amorphous
silicon type solar cell has been noted because it can provide an improved
mass productivity and a lower cost, compared with a solar cell made of a
single crystal silicon, for which various fabrication methods therefor
have been proposed.
In the solar cell generation, unit modules of the solar cell are
interconnected in series or parallel to form a unit so that a desired
current or voltage is obtained. It is required that in each unit module,
no disconnection or short-circuit may occur, and there is less dispersion
in the output voltage or output current between unit modules. For this
purpose, the uniformity in the characteristics of a semiconductor layer is
the most determinative factor in the step of fabricating the unit module.
Also, to facilitate the module design and simplify the assembling process
of module, the ability to form a semiconductor deposited film having
excellent characteristics over a large area can provide a greater mass
production of the solar cell and yield a great reduction of production
cost.
The semiconductor layer which is an important component of the solar cell
contains semiconductor junctions such as pn junction or pin junction. Such
a semiconductor junction is formed by sequentially laminating
semiconductor layers having different conduction types, or ion implanting
or thermally diffusing a dopant having a different conduction type into
the semiconductor layer of a certain conduction type. In fabricating the
amorphous silicon type solar cell as above described, it is well known
that a source gas containing an element as a dopant such as phosphine
(PH.sub.3) or diborane (B.sub.2 H.sub.6) is mixed into a main source gas
such as a silane gas. The mixed source gas is decomposed by glow discharge
or the like to obtain a semiconductor film having a desired conduction
type, and the semiconductor film is sequentially laminated on a desired
substrate, so that a semiconductor junction is easily obtained. Thus, in
fabricating an amorphous silicon type solar cell, it is common that by
providing a separate film forming chamber corresponding to each
semiconductor layer, each semiconductor layer is formed within this film
forming chamber.
A deposited film forming method relying on the plasma CVD suitable for the
fabrication of such an amorphous silicon type solar cell has been
disclosed in U.S. Pat. No. 4,400,409 with regard to the roll to roll mode.
This deposited film forming method is such that a plurality of glow
discharge regions are provided, a long-size strip-like substrate is
disposed along a passage penetrating through those glow discharge regions
in sequence. Semiconductor layers having necessary conduction types are
deposited in respective glow discharge regions separately provided while
the strip-like substrate is being continuously conveyed in a longitudinal
direction thereof. Thereby, the solar cell having a desired semiconductor
junction can be formed consecutively. Note that in this deposited film
forming method, to prevent a dopant gas for use in each glow discharge
region from diffusing or mixing into other glow discharge regions, the
glow discharge regions are separated from each other by a slit-like
separation passage called as a gas gate, in which separation passage there
is a flow of a scavenging gas such as Ar or H.sub.2. With such a
constitution, the deposited film forming method according to the roll to
roll mode can be suitably applied to the fabrication of semiconductor
elements in the solar cell.
On the other hand, an attempt for improving the photoelectric conversion
efficiency of an amorphous silicon type solar cell has been made in which
it has been found that when group-IV alloy semiconductors such as
a-SiGe:H, a-SiGe:F, a-SiGe:H:F, a-SiC:H, a-SiC:F, a-SiC:H:F is used as the
i-type (intrinsic) semiconductor layer, the forbidden band width (band
gap: E.sub.g.sup.opt) of this i-type semiconductor layer is appropriately
changed continuously in a direction of film thickness from the incident
side of light, so that the open voltage (V.sub.oc) or curve factor (fill
factor: FF) can be greatly improved (20th IEEE PVSC. 1988, "A Novel Design
for Amorphous Silicon Solar Cells" S Guha J. Yang, et al.).
However, the deposited film forming method as above described has a
drawback. The large area deposited film can not be uniformly formed even
though the composition is continuously changed in the direction of film
thickness to change continuously the band gap. This drawback is
specifically described in the following.
In the deposited film forming method according to the roll to roll mode as
above described, the deposited film is formed while the strip-like
substrate is being continuously moved, whereby the formation of the
deposited film on the substrate is carried out while the substrate passes
through the glow discharge regions. Accordingly, the film thickness of the
deposited film can be controlled relatively easily by the deposition rate
and the passing speed through the glow discharge regions. On the other
hand, in order to provide a composition distribution in a direction of
film thickness, it is necessary to provide a distribution in a moving
direction of the substrate in a film forming atmosphere within the glow
discharge region, because the substrate is moved continuously. However, it
is difficult to provide repetitively such a distribution in the film
forming atmosphere which depends on the composition or pressure of source
gas, or the energy density of glow discharge. Also, in a conventional
deposited film forming method with the substrate fixed therein, to provide
the distribution in the film forming atmosphere was not conducted, because
to continuously change the forbidden band width in a direction of film
thickness would impair the uniformity of the deposited film.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a deposited film forming
method and a deposited film forming apparatus wherein a deposited film
having a composition distribution in a direction of film thickness can be
continuously formed on a large substrate without variation in the
characteristics.
In the deposited film forming method and apparatus, a flow of a source gas
containing a plurality of kinds of deposited film source materials is
formed within the vacuum vessel in a forward direction equivalent and
parallel to a moving direction of the substrate and a reverse direction
opposite and parallel to the moving direction of the substrate, while a
substrate is continuously moved in a longitudinal direction of the
substrate within the vacuum vessel. A plasma is excited-within the vacuum
vessel by applying a discharge energy to each of a plurality of discharge
means arranged in a longitudinal direction to the substrate, whereby
deposited film is formed on the substrate. Since the flow of the source
gas containing a plurality of kinds of deposited film source materials is
formed in the forward and reverse directions parallel to the moving
direction of the substrate, and plasma is excited by applying a discharge
energy to each of a plurality of discharge means arranged in the
longitudinal direction of the substrate, the film forming conditions can
vary in respect to the moving direction of the substrate. Thus,
composition of deposited film formed can be varied at different positions
in the moving direction of the substrate. On the other hand, the substrate
is continuously moved, and the deposited film is continuously formed and
grown, so that the deposited film formed on the substrate can have a
different composition in a direction of film thickness.
In the deposited film forming method of the present invention, in order to
form a flow of a source gas containing a plurality of kinds of deposited
film source materials in the forward and reverse directions parallel to
the moving direction of the substrate, it suffices that source gas
discharge means for discharging the source gas uniformly over a width
direction of the substrate is provided opposed to the substrate, and
source gas exhaust means for exhausting the source gas over the width
direction of the substrate is provided. It is desirable that the source
gas discharge means and the source gas exhaust means are provided in a
pair, but it will be appreciated that the source gas exhaust means may be
provided at two positions on the forward and reverse sides along the
moving direction of the substrate. It will be also appreciated that a
plurality of pairs of the source gas discharge means and the source gas
exhaust means are provided. In this case, the source gas flows in a
direction parallel to the moving direction of the substrate in some
portion thereof, but in a direction opposite to the moving direction of
the substrate in the other portion. That is, the source gas can flow
appropriately formed in a combination of the forward and reverse
directions relative to the moving direction of the substrate.
The source gas discharge means is provided with a gas discharge hole for
discharging the source gas into a vacuum vessel. The shape of this gas
discharge hole may be arbitrary such as slit-like, circular, elliptical,
sponge-like or mesh-like, and the number of gas discharge holes may be
also arbitrary, although it is required that the gas be discharged
uniformly over the width direction of the substrate. In this case, it is
desirable that the diameter of the gas discharge hole is adjusted so as to
increase the amount of gas discharged through the gas discharge hole
corresponding to the neighborhood of an end portion of the substrate in
its width direction, to the extent depending on the internal pressure of
vacuum vessel and the flow rate of the source gas, so that the flow of the
source gas parallel to the moving direction of the substrate can be
accomplished.
On the other hand, the source gas exhaust means is provided with a gas
exhaust hole for exhausting the source gas. The shape of this gas exhaust
hole may be arbitrary such as slit-like, circular, elliptical, sponge-like
or mesh-like, and the number of gas exhaust holes may be also arbitrary,
although it is required that the gas be exhausted uniformly over the width
direction of the substrate. In this case, it is desirable to adjust the
diameter of the gas exhaust hole to increase the amount of gas sucked
through the gas exhaust hole corresponding to the neighborhood of an end
portion of the substrate in its width direction, the extent depending on
the internal pressure of vacuum vessel and the flow rate of the source
gas, so that the flow of the source gas parallel to the moving direction
of the substrate can be accomplished.
The source gas contains a plurality of kinds of deposited film source
materials, and desirably has different decomposition and deposition
efficiencies for respective deposited film source materials by plasma,
with which the degree of change in the film forming condition along the
moving direction of the substrate can be made larger. The decomposition
and deposition efficiencies can be changed variously depending on the kind
of the discharge energy or the discharge conditions (e.g., discharge
power, discharge frequency) for generating the plasma, the flow rate, flow
speed and pressure of the source gas within the vacuum vessel, and whether
the dilution gas for diluting the source gas may exist or not.
In the deposited film forming method of the present invention, it is
preferable that within the vacuum vessel, there is provided a film forming
vessel through which the substrate penetrates movably, within which the
source gas flows, plasma is produced, and a deposited film is formed on
the substrate. In this case, in order to prevent the discharge energy or
produced plasma from leaking out of this portion of the film forming
vessel through which the substrate penetrates, a grounded guard electrode
should be provided in this portion near the substrate. The distance
between the guard electrode and the substrate is desirably equal to or
less than the length of a dark space (a dark part of glow discharge) in
the produced plasma, for example, when the discharge energy is at a high
frequency (typically, 13.56 MHz). When the discharge energy is a microwave
(typically, 2.45 GHz), it is preferably one-fourth or less the wavelength
of microwave, and more preferably one-twentieth or less the wavelength.
The length of a portion of the guard electrode opposed to the substrate
along the moving direction of the substrate is preferably five times or
greater the distance between the substrate and the guard electrode, and
more preferably ten times or greater. Of course, the guard electrode is
desirably provided corresponding to the entire width of the substrate in
the width direction thereof.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic cross-sectional view showing the constitution of a
deposited film forming apparatus for use in carrying out a deposited film
forming method according to an embodiment of the present invention.
FIG. 2 is a schematic cross-sectional view showing the constitution of
another deposited film forming apparatus for use in carrying out the
deposited film forming method according to the embodiment of the present
invention.
FIG. 3 is a schematic cross-sectional view showing the constitution of a
continuous deposited film forming apparatus having incorporated the
deposited film forming apparatus as shown in FIG. 1.
FIG. 4 is a schematic cross-sectional view showing the constitution of a
continuous deposited film forming apparatus having incorporated the
deposited film forming apparatus as shown in FIG. 2.
FIGS. 5A to 5D are schematic cross-sectional views showing the
constitutions of solar cell.
FIGS. 6A to 6D are explanation views showing the band gap profiles of
i-type semiconductor layer.
FIGS. 7A to 7D are explanation views showing the fermi level profiles of
i-type semiconductor layer.
FIGS. 8 to 11 are characteristic views showing the results of secondary ion
mass spectrometry.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The preferred embodiments of the present invention will be described below
with reference to the drawings.
A deposited film forming apparatus 100 as shown in FIG. 1 is composed of a
substantially rectangular parallelepiped vacuum vessel 101, and first and
second film forming vessels 102, 103 provided within the vacuum vessel
101. The vacuum vessel 101 and each film forming vessel 102, 103 are made
of metal, and grounded therein. A long-size strip-like substrate 104 on
which deposited film is formed is introduced past a gas gate 129 attached
on a side wall to the left of the vacuum vessel 101, as shown, or on the
inlet side thereof, and led through a first film forming vessel 102 and a
second film forming vessel 103 past a gas gate 130 attached on a side wall
to the right of the vacuum vessel 101 as shown or on the outlet, side
thereof out of the vacuum vessel 101. To each gas gate 129, 130 is
connected a gate gas supply tube 135, 136 for supplying a gate-gas. The
strip-like substrate 104 can be continuously moved from a substrate
delivery vessel (not shown) connected to the gas gate 129 on the inlet
side toward a substrate winding vessel (not shown) connected to the gas
gate 130 on the outlet side. Also, on the vacuum vessel 101, an exhaust
tube 139 is attached to directly exhaust the vacuum vessel 101, and
connected to exhausting means (not shown) such as a vacuum pump.
The first film forming vessel 102 has first and second applicators 105, 106
mounted in juxtaposition along a moving direction of the strip-like
substrate 104 so as to be opposed to the strip-like substrate 104
penetrating through the first film forming vessel 102. Each applicator
105, 106 serves to introduce the microwave energy into the first film
forming vessel 102, and connected to one end of a respective wave guide
111, 112 with the other end thereof connected to a microwave power source
(not shown). At the position of attaching each applicator 105, 106 to the
first film forming vessel 102, there is provided a respective microwave
introducing window 108, 109 made of a material capable of transmitting the
microwave.
A first gas discharger 114 for discharging the source gas is mounted on a
side wall of the first film forming vessel 102 on the outlet side or to
the right thereof, and an exhaust tube 116 is attached to a side wall
thereof on the inlet side or to the left as shown so as to be opposed to
the first gas discharger 114. On the surface of the first gas discharger
114, a number of gas discharge holes (not shown) for discharging the
source gas are provided. The first gas discharger 114 has one end of a gas
supply tube 131 attached thereto which is connected to a source gas supply
source (not shown) such as a gas bomb. On the other hand, the exhaust tube
116 is connected via a connecting tube 118 to exhausting means (not shown)
such as a vacuum pump. On a mounting portion of the exhaust tube 116 on
the first film forming vessel 103 is attached a wire gauze 120 for the
adjustment of the exhaust flow, and preventing the microwave energy from
leaking therefrom.
On the opposite side of the strip-like substrate 104 to the first and
second applicators 105, 106 within the first film forming vessel 102,
there are provided a number of infrared lamp heaters 124 and a lamp house
122 for efficiently concentrating radiant heat from the infrared lamp
heaters 124 onto the strip-like substrate. Also, there is attached a
thermocouple 137 for monitoring the temperature of the strip-like
substrate 104 heated by the infrared lamp heaters 124, in contact with the
strip-like substrate 104.
The second film forming vessel 103 has substantially the same constitution
as the first film forming vessel 102, in which a third applicator 107 is
attached to be opposed to the strip-like substrate 104. The third
applicator 107 has a waveguide 113 attached thereto which is connected to
the microwave power source not shown, with a mounting portion of the third
applicator 107 serving as a microwave introducing window 110.
On the side wall of the second film forming vessel 103 on the inlet side, a
second gas discharger 115 is attached and connected via a source gas
supply tube 132 to a source gas supply source not shown. Also, on the side
wall of the second film forming vessel 103 on the outlet side, an exhaust
tube 117 is attached to be opposed to the second gas discharger 115, and
connected via a connecting tube 119 to exhausting means (not shown). On a
mounting portion of the exhausting tube 117 on the second film forming
vessel 103, there is provided a wire gauze 121. Further, the second film
forming vessel 103, like the first film forming vessel 102, is provided
with infrared lamp heaters 125, a lamp house 123 and a thermocouple 138.
The strip-like substrate 104, penetrating through the first and second film
forming vessels 102, 103, is introduced through an opening portion
provided on a side wall of the inlet side (to the left as shown) into the
first film forming vessel 102, then led out through an opening portion
provided on the side wall of the outlet side (to the right as shown), and
subsequently introduced through an opening portion provided on a side wall
of the inlet side into the second film forming vessel 103, and then led
out through an opening portion of the outlet side. The opening portion of
the first film forming vessel 102 on the inlet side, and the opening
portion of the second film forming vessel on the outlet side, are provided
with guard electrodes 126, 127, respectively. Since the opening portion of
the first film forming vessel 102 on the outlet side and the opening
portion of the second film forming vessel 103 on the inlet side are
adjacent to each other, there is provided a guard electrode 128 so as to
connect these both opening portions. Each of guard electrodes 126 to 128
is provided opposed to and close to the front surface of the strip-like
substrate 104 (which is opposite each applicator 105 to 107) extending
outward of the film forming vessel 102, 103, and grounded by grounding
means not shown. These guard electrodes 126 to 128 serve to prevent the
discharge energy or produced plasma from leaking therefrom.
Next, the operation of this deposited film forming apparatus 100 will be
described below.
First, the strip-like substrate 104 is extended from the substrate delivery
vessel (not shown) connected to the gas gate on the inlet side to the
substrate winding vessel (not shown) connected to the gas gate 130 on the
outlet side so as to penetrate through the deposited film forming
apparatus 100, and the vacuum vessel 101 and each film forming vessel 102,
103 are evacuated to a vacuum through the exhaust tubes 116, 118, 139. If
a determined degree of vacuum is reached, a gate gas is supplied from each
gate gas supply tube 135, 136 to each gas gate 129, 130. The gate gas is
exhausted mainly through the exhaust tube 139 connected to the vacuum
vessel 101.
Subsequently, the strip-like substrate 104 is heated to a predetermined
temperature by activating the infrared lamp heaters 124, while monitoring
the output of the thermocouple 137. And a source gas is supplied from each
source gas supply tube 131, 132 to each of the first and second gas
discharger 114, 115, which then discharges the source gas into each film
forming vessel 102, 103. The source gas supplied to each gas discharger
114, 115 contains a plurality of kinds of deposited film source materials.
A microwave energy is applied via each waveguide 111 to 113 to each
applicator 105 to 107.
Furthermore, substrate delivery means (not shown) provided within the
substrate delivery vessel (not shown) and substrate winding means (not
shown) provided within the substrate winding vessel (not shown) are
activated to move continuously the strip-like substrate 104 from the
substrate delivery vessel toward the substrate winding vessel.
In this way, in a space of the first film forming vessel 102 between the
strip-like substrate 104 and the first and second applicators 105, 106 (a
first film forming space 133), the source gas flows from the first gas
discharger 114 toward the exhaust tube 116, that is, in a direction
opposite to the moving direction of the strip-like substrate 104. Further,
because the microwave power is applied to the first and second applicators
105, 106, a microwave glow discharge is excited within the first film
forming space 133 to produce a plasma, and the source gas is decomposed by
the plasma so that a deposited film is formed on the strip-like substrate
104. At this time, the forming conditions of the deposited film may vary
depending on the position of the strip-like substrate 104 in the moving
direction thereof, because the source gas flows in a direction opposite to
the moving direction of the strip-like substrate 104, and the source gas
contains a plurality of kinds of deposited film source materials, so that
the deposited film formed on the continuously moving strip-like substrate
104 can have a distribution of composition in a direction of film
thickness. By controlling the microwave power to be applied to the first
and second applicators 105, 106, the composition distribution of the
deposited film in the direction of film thickness can be formed more
effectively. Note that due to the provision of guard electrodes 126, 128,
no leakage of the microwave energy or plasma from the first film forming
vessel 102 occurs.
In the second film forming vessel 103, like in the first film forming
vessel 102, a source gas is supplied to the second gas discharger 115, but
the source gas discharged from the second gas discharger flows in a
direction equivalent to the moving direction of the substrate toward the
exhaust tube 117, unlike in the first film forming vessel 102.
By applying a microwave power to the third applicator 107, a plasma
is-generated in a space between the strip-like substrate 104 and the third
applicator 107 (a second film forming space 134), so that a deposited film
is formed on the strip-like substrate 104. This deposited film has a
distribution of composition in the direction of film thickness.
Since the strip-like substrate 104 is continuously moved from the first
film forming vessel 102 toward the second film forming vessel 103, a
deposited film formed in the second film forming vessel 103 is laminated
on the deposited film formed in the first film forming vessel 102. Each
portion of the deposited film formed in each film forming vessel 102, 103
has a distribution of composition-in the direction of film thickness, so
that the entire deposited film has also a distribution of composition in
the direction of film thickness.
The distribution of composition in the direction of film thickness can be
changed abruptly by flowing the source gas in a forward direction
equivalent to the moving direction of the substrate and in a reverse
direction opposite thereto.
Next, a deposited film forming apparatus 200, apart from the deposited film
forming apparatus 100 as above described, for use in carrying out a
deposited film forming method of the present invention as shown in FIG. 2
will be described below. This deposited film forming apparatus 200 is to
excite the plasma by high frequency electric power, in which first and
second cathodes 201, 202 are provided instead of the applicators 105 to
107 for the deposited film forming apparatus 100 as shown in FIG. 1. This
deposited film forming apparatus 200 will be described below based on the
differences from the deposited film forming apparatus 100 as shown in FIG.
1.
A first cathode 201 is mounted via an insulating porcelain 205 within the
first film forming vessel 102 so as to be opposed to the strip-like
substrate 104, and connected via a high frequency lead wire 203 to one end
of a high frequency power source not shown with the other end grounded
therein. On the other hand, a second cathode 202, like the first cathode
201, is mounted via the insulating porcelain 205 within the second film
forming vessel 103, and connected via a high frequency lead wire 204 to
one end of the high frequency power source not shown with the other end
grounded therein.
Next, the operation of this deposited film forming apparatus 200 will be
described below.
Like the deposited film forming apparatus 100 as shown in FIG. 1, if a high
frequency power is applied to the first and second cathodes 201, 202 while
source gases are discharged from the first and second gas dischargers 114,
115 into the first and second film forming vessels 102, 103, respectively,
and the strip-like substrate 104 is continuously moved in its longitudinal
direction, a high frequency glow discharge is excited within each of the
first and second film forming spaces 133, 134, generating a plasma, so
that the deposited film is formed on the strip-like substrate 104. At this
time, the source gas flows in the forward and reverse directions parallel
to the moving direction of the strip-like substrate 104 within each film
forming space 133, 134, whereby the film forming conditions can vary
depending on the position of the strip-like substrate 104 in the moving
direction thereof, so that the deposited film formed has a distribution of
composition in the direction of film thickness.
Next, a continuous deposited film forming apparatus 300 with the deposited
film forming apparatus 100 as shown in FIG. 1 incorporated therein will be
described with reference to FIG. 3.
This continuous deposited film forming apparatus 300 is suitable for
forming a semiconductor element having the pin junction on the strip-like
substrate 104, in which a substrate delivery vessel 301, a first impurity
layer forming vacuum vessel 302, the deposited film forming apparatus 100,
a second impurity layer forming vacuum vessel 303, and a substrate winding
vessel 304 are connected in series via four gas gates 311, 129, 130 and
312. Those gas gates 311, 129, 130, 312 are coupled with gate gas supply
tubes 313, 135, 136, 314 for the supply of gate gas, respectively.
The substrate delivery vessel 301 serves store and deliver the strip-like
substrate 104 to the substrate winding vessel 304, and has a bobbin 321
mounted therein around which the strip-like substrate 104 is wound. Also,
the substrate dilevery vessel 301 has an exhaust tube 322 attached therto
which is connected to exhausting means not shown, and has a throttle valve
323 provided halfway thereof for controlling the pressure within the
substrate delivery vessel 301. Furthermore, the substrate delivery vessel
302 is provided with a pressure gauge 324, a heater 325 for heating the
strip-like substrate 104, and a conveying roller 326 for supporting and
conveying the strip-like substrate 104. Note that the bobbin 321 is
connected to a substrate delivery mechanism not shown for delivering the
strip-like substrate 104.
The first and second impurity layer forming vacuum vessels 302, 303 have
the identical structure to form a p-type or n-type semiconductor layer.
Each impurity layer forming vacuum vessel 302, 303 is coupled with an
exhaust-tube 330 connected to exhausting means not shown, and halfway of
the exhaust tube 330, there {s provided a throttle valve 331 for
controlling the internal pressure of the impurity layer forming vacuum
vessels 302, 303. The strip-like substrate 104 is supported by two
conveying rollers 332, with the end portions thereof in its width
direction supported by support rings 333, so as to be movable along the
lateral surface of a substantially cylindrical space within each of the
impurity layer forming vacuum vessels 302, 303. And a source gas
introducing conduit 334 is provided in a central portion of the
cylindrical space, and an applicator 335 for introducing the microwave
into this cylindrical space at a portion corresponding to a top face of
the cylindrical space. This applicator 335 is connected to a microwave
power source not shown. Further, a heater 336 for heating the strip-like
substrate 104 is provided within each of the impurity layer forming vacuum
vessels 302, 303.
The substrate winding vessel 304 serves to wind the strip-like substrate
104 on which the deposited film is formed, and has a constitution
identical to that of the substrate delivery vessel 301, except that a
bobbin 321 is connected to a substrate winding mechanism not shown for
winding the strip-like substrate 104.
Next, the operation of the continuous deposited film forming apparatus 300
will be described below mainly when forming a semiconductor element having
the pin junction.
First, the strip-like substrate 104 is extended from the substrate delivery
vessel 301 to the substrate winding vessel 304. Subsequently, the
substrate delivery vessel 301, each impurity layer forming vacuum vessels
302, 303, the deposited film forming apparatus 100 and the substrate
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