JP2001288573A - Deposited film forming method and deposited film forming equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a homogeneous deposited film on a strip-like substrate 207. SOLUTION: The inside of a vacuum vessel 203 for keeping its inside in a reduced pressure state has a bar-shaped antenna-like discharge electrode 101 having a hollow part connected to a gas-introducing pipe 211b and a plurality of outlet holes 107 communicating from the hollow part to the outside. While discharging source gas to be a raw material for the deposit film via the outlet holes 107, high frequency power is introduced to the discharge electrode 101 to make it discharge electricity. By this procedure, the source gas is formed into plasmic state in the vicinity of the surface of the discharge electrode 101, and the resultant plasmic source gas is practically uniformly introduced to the deposit-film-formation surface of the strip-like substrate 207, by which the homogeneous deposited film can be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deposited film forming method and a deposited film forming apparatus for forming a semiconductor thin film, such as a photovoltaic element, by a plasma CVD method.
In particular, the present invention relates to a deposited film forming method and a deposited film forming apparatus for continuously forming a semiconductor thin film of a photovoltaic element such as a solar cell using amorphous silicon or an amorphous alloy.

[0002]

2. Description of the Related Art For amorphous silicon, Si
A raw material gas containing Si such as H ⁴ or Si ² H ⁶ is decomposed by high-frequency discharge into a plasma state, which is deposited on a substrate placed in the plasma to form a film,
A method of forming a thin film by a plasma CVD method is generally used. Since this amorphous silicon film can be formed into a large-area thin film by a plasma CVD method, a semiconductor device having a large area can be formed relatively easily as compared with crystalline silicon or polycrystalline silicon. For this reason, amorphous silicon films are widely used in semiconductor devices requiring a large area, specifically, solar cells, photosensitive drums of copying machines, image sensors of facsimile machines, thin film transistors for liquid crystal displays, and the like.

An apparatus for manufacturing a semiconductor device having a large area containing amorphous silicon is disclosed in US Pat.
A continuous plasma CVD apparatus adopting a roll-to-roll method described in Japanese Patent No. 0,409 or the like is known.

[0004] This continuous plasma CVD apparatus has a sufficiently long belt-like substrate transfer means, and a plurality of glow discharge chambers provided along the belt-like substrate transfer path. According to this continuous plasma CVD apparatus, in each glow discharge chamber, the strip-shaped substrate is continuously transported in the longitudinal direction thereof while depositing and forming a required conductive semiconductor film. Thus, semiconductor layers are sequentially formed in a plurality of glow discharge chambers, and a large-area semiconductor device in which a plurality of semiconductor layers are sequentially stacked so as to have a semiconductor junction can be continuously formed.

As described above, by using the roll-to-roll type continuous plasma CVD apparatus, a large-area semiconductor device can be efficiently operated by continuously operating for a long time without repeatedly starting and stopping the manufacturing apparatus. Since it can be manufactured, high productivity can be obtained.

In the case of forming an amorphous silicon film by the plasma CVD method, a high frequency of an RF frequency (around 13.56 MHz) has been generally used as a high frequency for discharge. However, recently, plasma CVD using a high frequency of VHF frequency (about 30 to 300 MHz)
Is attracting attention.

For example, "Amorphous Sili"
con Technology "1992, p. 15 ~
26 (Materials Research Soc
iety Symposium Proceeding
s Volume 258) is 13.5 by using the high frequency of the VHF frequency as the high frequency for discharge.
It is described that a film formation rate can be remarkably increased as compared with a case where a high frequency of an RF frequency of 6 MHz is used, and a good deposited film can be formed at a high speed.

[0008]

However, in a roll-to-roll type continuous plasma CVD apparatus for forming a large-area deposited film, VHF is used as a high frequency for discharge.
The use of a high frequency has the following problems.

One problem is that, in order to generate a uniform discharge over a large area, if a large-area flat plate discharge electrode generally used in discharge at an RF frequency is used for discharge at a VHF frequency, the wavelength becomes shorter. As a result, the potential distribution on the surface of the discharge electrode becomes non-uniform, so that a uniform and stable discharge cannot be generated over the entire discharge electrode, and uniform plasma can be generated in a large area. The problem is that you can't.

Therefore, when a rod-shaped or ladder-type antenna-shaped discharge electrode is used, a uniform plasma can be generated directly above the discharge electrode member. The plasma density rapidly decreases as the distance from the discharge electrode increases, and when multiple discharge electrodes are used, the distance between the discharge electrode members, such as the middle area between the rod-shaped discharge electrodes and the gap of the ladder, is reduced. The plasma density is significantly reduced. For this reason, the deposition rate of the semiconductor film is greatly different between a region immediately above the discharge electrode member and a region apart from the discharge electrode member. The difference in the deposition rate leads to the difference in the film quality. Therefore, a semiconductor film having a different film quality is sequentially formed on the belt-shaped substrate as it is transported, and a structure in which a plurality of semiconductor films having different film qualities are stacked is obtained. Originally, it is important that the semiconductor film formed in one glow discharge chamber is uniform and has no interface. If the above-described structure is formed in the semiconductor layer, the characteristics of the semiconductor device are unfavorably affected. Will appear.

Another problem is that when a voltage of a VHF frequency is applied to an antenna-like discharge electrode, local heating that does not occur when a voltage of an RF frequency is applied occurs. Depending on the pressure in the discharge chamber and the input power at the time of discharge, the tip of the discharge electrode, the root, etc.
A portion of the discharge electrode glows during discharge, as if a standing wave had risen there. When such local heating occurs, the band-shaped substrate is heated by radiant heat from the heated portion of the discharge electrode, and the temperature distribution on the band-shaped substrate becomes non-uniform, so that the deposition rate distribution of the semiconductor film is also non-uniform. And the deposition rate over time also changes, thereby deteriorating the uniformity of the film quality. Also, if left undisturbed, the red-hot portion of the discharge electrode will be deformed, and furthermore, the mechanical strength of the red-hot portion will be reduced and will not be able to withstand the weight of the discharge electrode, causing bending, etc.
This will result in severe damage to the deposited film forming apparatus.

Accordingly, an object of the present invention is to stably maintain a uniform discharge over a large area for a long period of time, and to provide a high-quality and excellent uniformity over a large area on a substrate moving on a discharge electrode in a discharge chamber. It is an object of the present invention to provide a deposited film forming method and a deposited film forming apparatus capable of forming a deposited film having a property.

[0013]

In order to achieve the above-mentioned object, a method for forming a deposited film according to the present invention comprises introducing a raw material gas into a vacuum vessel whose inside is kept under reduced pressure through a gas introduction pipe. A step of introducing electric power to a discharge electrode disposed in the vacuum vessel to discharge the plasma, thereby forming a plasma; and a step of depositing the plasma-converted source gas on a substrate disposed in the vacuum vessel. Plasma CVD having
In the method of forming a deposited film by a method, as a discharge electrode, an antenna-like discharge electrode having a hollow portion connected to a gas inlet tube and a plurality of emission holes communicating from the hollow portion to the outside is provided, and the raw material gas is hollow. It is characterized in that it is released from the discharge hole through the part.

According to this method, the raw material gas released from the discharge hole is efficiently turned into plasma near the surface of the antenna-like discharge electrode, and is discharged from the plurality of discharge holes. The source gas uniformly converted into plasma can be introduced.

A more specific method of supplying the raw material gas which has been substantially uniformly turned into plasma onto the substrate is a rod-like shape, in which discharge holes are arranged in one or more rows in the longitudinal direction. There is a method using an antenna-like discharge electrode. By doing so, the source gas can be introduced substantially uniformly in the longitudinal direction of the antenna-like discharge electrode. Further, by discharging the source gas from the emission holes arranged in the base over a width exceeding the width in the longitudinal direction of the antenna-like discharge electrode, the source gas is substantially distributed in the longitudinal direction of the antenna-like discharge electrode over the entire width of the base. Can be introduced evenly.

Further, by discharging the source gas from the discharge holes opened in a plurality of directions from the antenna-like discharge electrode toward the deposition film forming surface of the substrate, the source gas is released from the deposition film forming surface of the substrate. It can be introduced substantially evenly over the entire surface.

In the present invention, the antenna-like discharge electrode is
By using a material having a thermal conductivity of at least 70 W / (m · K) at 500 ° C., local heating of the antenna-like discharge electrode can be effectively reduced. As the material of the antenna-like discharge electrode, it is desirable to use a metal material having a high melting point, so that it has a high thermal conductivity and is not easily deformed even at a high temperature by performing discharge for a long time. Specifically, one of tungsten, molybdenum, and nickel, or an alloy containing at least one of these metals, or a modified metal obtained by adding additives for improving various properties to these metals or alloys It is desirable to use a modified alloy.

In the present invention, a gas introduction passage communicating with the hollow portion of the antenna-like discharge electrode and the gas introduction pipe is provided, and a power supply conductor is connected. Providing a conductive electrode support for transmitting the antenna-like discharge electrode to the electrodes, and providing a dielectric so as to surround a connection between the antenna-like discharge electrode and the conductive electrode support in a vacuum vessel; By providing an earth shield so as to further surround the body, preventing discharge at unnecessary places and suppressing the capacitance component of the power introduction path, thus reducing power loss and efficiently introducing power. Can be.

The method for forming a deposited film according to the present invention has a feature that a uniform deposited film can be formed stably over a long period of time. The mechanism can be suitably applied to a deposition film forming method in which a deposition film is continuously deposited on a belt-shaped substrate while being continuously transported so as to pass near an antenna-shaped discharge electrode.

In the method of forming a deposited film according to the present invention, since an antenna-like discharge electrode is used, it is difficult to generate a uniform plasma when a flat discharge electrode is used. The present invention can be suitably applied to a method of forming a deposited film using power of a frequency as power for plasma generation.

The deposition film forming apparatus according to the present invention comprises a vacuum vessel for keeping the inside of the vacuum vessel in a reduced pressure state, a gas introduction pipe for introducing the raw material gas into the vacuum vessel, and a plasma for converting the raw material gas into plasma by electric discharge. A discharge electrode disposed in a vacuum vessel, and a deposition film forming apparatus for forming a deposited film on a substrate disposed in the vacuum vessel by a plasma CVD method, wherein the discharge electrode is an antenna-like discharge electrode. In addition, it has a hollow portion connected to the gas inlet tube and a plurality of discharge holes communicating from the hollow portion to the outside.

In the deposited film forming apparatus according to the present invention, the input power is set to a relatively high frequency, thereby increasing the plasma density and forming the deposited film at a higher speed. By setting the wavelength to be relatively long, the frequency of the power supplied to the antenna-like discharge electrode is set to 1 so that a more uniform deposited film can be formed.
It is desirable to be able to select appropriately from 3.56 MHz to 2.45 GHz.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. In addition, the knowledge obtained upon completing the present invention, its operation, and the like will also be described.

FIG. 1 shows the structure of a deposited film forming apparatus according to this embodiment.
Vacuum container 2 provided with antenna-like discharge electrode 101
FIG. 1A is a schematic cross-sectional view of FIG. 1A, and FIG. 1B is a cross-sectional view taken along line BB of FIG.
FIG. 2 is a diagram showing a detailed shape of the antenna-like discharge electrode 101 of FIG. 1 together with a dimension example. FIG.
FIG. 2B is a cross-sectional view taken along line AA of FIG. FIG.
1 is an overall schematic diagram of a deposited film forming apparatus of the present embodiment, which is a roll-to-roll type continuous plasma CVD apparatus. FIG. 1 is a conceptual diagram, and details of the heating unit 210 and the like are partially omitted.

As shown in FIG. 3, in this deposited film forming apparatus, a bobbin 206 around which a band-shaped substrate 207 for forming a semiconductor film is wound is disposed, and a feeding mechanism of the band-shaped substrate 207 is disposed. A vacuum vessel 201 having a vacuum vessel 201 and a vacuum vessel 205 in which a winding mechanism for a strip-shaped substrate 205 on which a semiconductor film is formed is disposed;
A transport path for the band-shaped substrate 207 is formed between the vacuum chamber 205 and the vacuum container 205. Along the transport path of the band-shaped substrate 207, a vacuum container 202 for forming a semiconductor layer of the first conductivity type.
And a vacuum container 203 for forming an i-type semiconductor layer and a container 204 for forming a second conductive type semiconductor layer. Between each of the vacuum containers 201 to 205,
Narrow passages through which the band-shaped substrate 207 can pass are provided, and each passage is provided with a gate gas introduction pipe 209a, 209b, 209c, 209d for introducing a gate gas, respectively. Gas gates 208a, 208b, and 208 are provided for preventing gas from flowing between the vacuum vessels 201 to 205.
208c and 208d are formed.

Each of the vacuum vessels 202 to 204 is provided with an exhaust pipe connected to a vacuum pump (not shown) for reducing the pressure inside the exhaust pipe. The exhaust pipe is provided for adjusting the internal pressure. Throttle valves 212a, 212b,
212c is provided. Each vacuum vessel 202-204
Inside, heating means 210a, 210b, 210c for heating the band-shaped substrate 207 to a temperature suitable for processing is provided at a position facing the upper surface of the band-shaped substrate 207.

In the vacuum chambers 202 and 204 for performing the plasma CVD process at the RF frequency, a belt-like substrate 207 is provided.
The flat plate discharge electrodes 213a and 213b connected to a high-frequency power source (not shown) are provided at positions facing the lower surface of the flat plate. Further, the vacuum vessels 202 and 204 are provided with gas introduction pipes 211a and 211c for introducing a source gas serving as a raw material of the semiconductor film from the gas introduction means (not shown) to the vicinity of the flat plate discharge electrodes 213a and 213b. .

On the other hand, the vacuum vessel 203 is for performing a plasma CVD process at a VHF frequency, which is a feature of the present invention. Hereinafter, a configuration around a power supply path for plasma generation in the vacuum container 203 will be described.

As shown in FIGS. 1 to 3, at a position in the vacuum vessel 203 facing the lower surface of the band-shaped substrate 207, the tube extends in a direction substantially perpendicular to the transport direction of the band-shaped substrate 207.
A cylindrical antenna-shaped discharge electrode 101 having a rounded tip is provided. As shown in FIGS. 1 and 2, a hollow portion is provided inside the antenna-like discharge electrode 101 in order to introduce a raw material gas around the antenna-like discharge electrode 101.
A discharge hole 107 communicating from the hollow portion to the outside is provided. The emission holes 107 are arranged in two rows so as to be arranged in the longitudinal direction of the antenna-like discharge electrode 101, and the emission holes 107 of each row are arranged.
Are disposed so as to face in directions inclined about 45 ° to the left and right from the vertical upper direction.

The antenna-like discharge electrode 101 is connected to the power supply conductor 1.
04 and the gas introduction pipe 211b are supported by the conductive electrode support 102 connected thereto. Gas inlet pipe 2
Reference numeral 11b extends to a source gas supply source (not shown) disposed outside the vacuum vessel 203. Inside the conductive electrode support 102, a gas introduction passage communicating with the hollow portion inside the antenna-like discharge electrode 101 and the gas introduction pipe 211b is provided, and the source gas is supplied from the gas supply source to the gas introduction pipe. 211b, is supplied to the antenna-like discharge electrode 101 through the conductive electrode support 102, and is emitted around the antenna-like discharge electrode 101.

Inside the vacuum vessel 203, around the antenna-shaped discharge electrode 101, a discharge box 106 for confining plasma generated by discharge is arranged so that film deposition does not occur in unnecessary regions.

Around the connecting portion between the antenna-like discharge electrode 101 and the conductive electrode support 102, a cylindrical dielectric 10
3, and further around it, an earth shield 105,
Each is arranged so as to surround it with a gap.

Next, each component will be described in more detail. (1) Antenna-shaped discharge electrode, conductive electrode support, and power supply conductor As the power supply conductor 104, a coaxial cable or the like is used. The power supply conductor 104 is for supplying high frequency power.
The high-frequency power extends to a high-frequency power supply (not shown) arranged outside the vacuum vessel 203, and the high-frequency power is supplied to the antenna-like discharge electrode 101 from the high-frequency power supply via the power supply conductor 104 and the conductive electrode support 102. .

The antenna-like discharge electrode 101 and the belt-like base 20
7, the antenna-like discharge electrode 101 and the discharge box 10
It is preferable that the distance from the wall surface 6 is set to a distance that does not cause abnormal discharge in consideration of the pressure in the vacuum vessel 203 at the time of discharge, discharge power, and the like.

The provision of the discharge box 106 has the advantage that film deposition in unnecessary areas can be prevented and the time required for maintenance can be shortened. However, without providing the discharge box 106, the wall of the vacuum vessel 203 can be provided. In addition, a deposition-preventing plate for preventing film deposition on a wall surface may be directly installed. In this case, it is desirable to set the distance between the deposition-preventing plate surface and the antenna-like discharge electrode 101 to a distance where abnormal discharge does not occur.

Since the conductive electrode support 102 is connected to the antenna-like discharge electrode 101 to form one power introduction path, the electric power propagation is performed so as not to form a sudden impedance change portion in this power introduction path. It is desirable that the outer shape of the cross section orthogonal to the direction be as identical as possible to the outer shape of the cross section of the antenna-like discharge electrode 101. The material of the conductive electrode support 102 is generally a stainless steel material. However, in order to improve the power transmission efficiency, for example, A
A treatment for improving conductivity, such as a plating treatment, may be performed.

By setting the power supplied to the antenna-like discharge electrode 101 to a relatively high frequency, the plasma density can be increased and a deposited film can be formed at a higher speed. On the other hand, by setting the input power to a relatively low frequency, that is, a relatively long wavelength, a more uniform deposited film can be formed. Therefore, the frequency of the power supplied to the antenna-like discharge electrode 101 is 13.56 MHz.
As described above, it is desirable that the frequency can be appropriately selected as required from 2.45 GHz or less.

The shape of the antenna-like discharge electrode 101 is as follows.
It is preferable to adopt a structure in which the radiation of the high-frequency power smoothly proceeds and the concentration of the electrolysis is less likely to be concentrated on a specific portion of the radiation surface. Further, it is desirable that the source gas discharge holes 107 are formed in one or more rows in the longitudinal direction of the antenna-like discharge electrode 101, over a length exceeding the width of the strip-shaped base 207. It is desirable that the diameter of the discharge holes 107 be as small as possible so that the gas pressure distribution inside the antenna-like discharge electrode 101 is not significantly affected by gas release from each of the discharge holes 107. The formation interval of the discharge holes 107 is also
Since the discharge holes 107 have an interval, the band-shaped substrate 207 is formed.
It is desirable to make the deposition rate as small as possible so as not to cause a large unevenness in the deposition rate on the substrate.

The material of the antenna-like discharge electrode 101 is made of a material having a high thermal conductivity so that local heating of the antenna-like discharge electrode 101 at a sudden change in the impedance of the power introduction path due to the device structure or the like can be eased. It is desirable. Therefore, the following comparison was made using a deposited film forming apparatus provided with the antenna-like discharge electrodes 101 made of materials A to E having different thermal conductivities. That is, 100 sccm (sc) of SiH ₄ is used as a source gas.
cm: flow rate corresponding to 1 cm ³ / min with gas in a standard state),
H ₂ is supplied at 500 sccm, a high frequency power of 700 W at a frequency of 100 MHz is supplied, the pressure in the vacuum vessel 203 is set to 20 mTorr (2.67 Pa), and the belt-like substrate 207 is supplied.
At a temperature of 350 ° C., a thin film was deposited on the band-shaped substrate 207, the prepared band-shaped substrate 207 was cut out every 10 m, and the thickness distribution of the thin film on the cut-out band-shaped substrate 207 was examined. Table 1 summarizes the resulting film thickness deviations, which are the ratios obtained by dividing the film thickness measured at each position on the belt-shaped substrate 207 by the average film thickness.

[0040]

【table 1】

From the results shown in Table 1, it can be seen that the use of a material having a high thermal conductivity makes it possible to keep the film pressure deviation small. In the deposited film forming apparatus of the present invention, in particular, a material having a thermal conductivity at 500 ° C. of 70 W / (m · K) or more, which can make the film thickness deviation ± 10% or less, is used as the antenna-like discharge electrode. Desirable as the material of 101.

As described above, the antenna-like discharge electrode 101 has a high thermal conductivity, a high melting point and a high melting point, so that the occurrence of local overheating can be suppressed even if the discharge is performed for a long time. It is desirable to use a metal material having a high mechanical strength underneath, such as tungsten, molybdenum, nickel, an alloy containing at least one of these metals, or a metal, alloy It is preferable to use a modified metal or a modified alloy to which various additives for improving characteristics are added. (2) Earth Shield The earth shield 105 has a function of preventing high-frequency power supplied from the high-frequency power supply from being discharged at unnecessary places in order to efficiently transmit power to the antenna-like discharge electrode 101. Therefore, as a constituent material of the earth shield 105, a conductor having no magnetism is suitable. (3) Dielectric By providing the dielectric 103 between the conductive electrode support 102 and the earth shield 105, the distance between the conductive electrode support 102 and the earth shield 105 is increased, and the abnormal discharge is suppressed. In addition, the capacity component of the power introduction path can be suppressed, and as a result, the input power loss can be reduced.

As a constituent material of the dielectric 103, since it is arranged so as to surround the conductive electrode support 103, thermal conductivity, vacuum characteristics (gas release characteristics), mechanical strength,
It is desirable to use a material that is excellent in workability, electrical insulation, heat resistance, high-frequency characteristics, and the like. In particular, ceramics can be suitably used as a material having such characteristics.

With respect to the structure of the dielectric 103, the following points are particularly important, particularly with respect to a portion exposed to plasma. (A) The structure does not contact the discharge electrode.

At the time of forming the deposited film, the surface of the member of the deposited film forming apparatus which is exposed to the plasma, except for the band-shaped substrate 207,
A part of the source gas converted into plasma may form a deposited film. In the case where the deposited film is formed in this manner, particularly when the conductive semiconductor film is formed, the conductive material is applied to the member at the ground potential, particularly to the dielectric 103 arranged near the antenna-like discharge electrode 101. Is formed, the antenna-like discharge electrode 101 and the dielectric 1
03 is deteriorated. Also, even when an insulating deposited film is formed, if the dielectric 103 is heated by contacting the antenna-shaped discharge electrode 101 which has been heated by the discharge, the dielectric 103 is heated.
, The dielectric loss tangent of the first electrode may be significantly increased, and furthermore, local dielectric heating may occur, so that stable discharge may not be maintained.

In order to suppress such adverse effects due to the formation of the deposited film on the dielectric 103, it is desirable that the structure of the dielectric 103 does not contact the antenna-like discharge electrode 101. This is indispensable as a measure for avoiding insulation deterioration between the antenna-like discharge electrode 101 and the dielectric 103, particularly in a deposition film forming apparatus for forming a conductive semiconductor film. (B) An end face shape having no sharp edges.

When a conductive semiconductor film or the like is deposited on the surface of the dielectric 103 and this conductor portion is charged, the charges gather at the sharp edge of the end face to form a strong electric field portion, which is a counter electrode to this portion. There is a concern that abnormal discharge may occur between the antenna-shaped discharge electrode 101 and the antenna-shaped discharge electrode 101. Therefore, in addition to the countermeasure (a), the end face of the dielectric 103 is subjected to processing such as chamfering and R processing to form an end face shape without sharp edges, thereby forming a conductive deposited film. In this case, insulation deterioration between the antenna-like discharge electrode 101 and the dielectric 103 via the deposited film can be more effectively prevented.

In particular, in the case of ceramics, chips and cracks may occur during maintenance work, and sharp edges may be formed. This portion may become a site of abnormal discharge. You need to be careful enough.

Next, a method of forming a deposited film by the deposited film forming apparatus of the present embodiment will be described in accordance with a preparation procedure.

First, the belt-like substrate 20 is placed in the vacuum vessel 201.
The bobbin 206 around which the wire 7 is wound is set, and the belt-shaped substrate 207 is placed on the gas gate 208a, the vacuum chamber 202 for forming a semiconductor layer of the first conductivity type, and the gas gate 208b, i
Vacuum container 203 and gas gate 20 for forming mold semiconductor layer
8c, Vacuum container 20 for producing second conductive type semiconductor layer
4. Pass the gas through the gas gate 208d to the vacuum vessel 205, and adjust the tension to a level that does not cause slack.

Therefore, the inside of each of the vacuum vessels 201 to 205 is
A vacuum is drawn by a vacuum pump (not shown) to reduce the pressure to a predetermined pressure.

Next, the gas gates 208a to 208d are
From gate gas inlet pipe 209A～209d, flushed with H ₂ at a predetermined flow rate as a gate gas, heating means 210a~2
By 10d, the belt-like substrate 207 is heated to a predetermined temperature suitable for forming each deposited film. Then, a raw material gas serving as a raw material of each deposited film is introduced into the gas introducing means 211a to 211c at a predetermined flow rate. At this time, while the gas is being introduced, the pressure in the vacuum vessels 202 to 204 is increased.
In order to have a predetermined pressure suitable for plasma CVD processing,
While looking at the pressure gauge (not shown), the throttle valve 212a
Adjustment is made by changing the opening of 212c.

Thereafter, electric power of a predetermined output RF frequency is introduced into the flat plate discharge electrodes 213a and 213c of the vacuum vessels 202 and 204, and the antenna-like discharge electrode 101 of the vacuum vessel 203 is introduced.
Then, power of a predetermined output VHF frequency is introduced. Then, by transporting the belt-like substrate 207, a first conductive type semiconductor layer, an i-type semiconductor layer, and a second conductive type semiconductor layer are sequentially stacked on the belt-like substrate 207.

In the deposition film forming apparatus of this embodiment, VHF
In the antenna-like discharge electrode 101 which performs discharge at a frequency, since the source gas is released from the discharge hole 107,
The released source gas can be efficiently turned into plasma near the surface of the antenna-shaped discharge electrode 101, and the source gas that has been turned into plasma can be effectively dispersed toward the belt-shaped substrate 207 and supplied. As a result, the antenna-like discharge electrode 10 is not only positioned directly above the antenna-like discharge electrode
The source gas in the form of plasma can be supplied substantially evenly to a region away from the first region, and a deposited film of uniform film quality can be formed at a uniform deposition rate.

Next, an example in which a specific semiconductor element is formed by the above-described method for forming a deposited film according to the embodiment of the present invention will be described. The following examples are exemplifications, and the present invention is not limited to these examples.

(Embodiment 1) In this embodiment, the belt-like substrate 20
7 shows an example in which single-type photovoltaic elements are continuously formed. At this time, as the antenna-like discharge electrode 101,
As shown in FIG. 2, the diameter is 20 mm, the length is 600 mm,
Gas emission holes 107 arranged in two rows in the longitudinal direction
(Tungsten) antenna-shaped discharge electrode having the following characteristics. The discharge hole 107 has a hole diameter of 1.0 mm and a pitch of 50 m.
m. AlN is used as the dielectric 103, and 1 m is provided between the dielectric 103 and the antenna-like discharge electrode 101.
m.

The band-like substrate 207 has a width of 300 mm,
After sufficiently degreased and washed a SUS430BA substrate having a length of 200 m and a thickness of 0.13 mm, a silver thin film of 100 nm (reflection layer) and a ZnO thin film of 1 μm (reflection increase) were formed as a lower electrode by sputtering. Layer) The thing which vapor-deposited was used.

After setting the belt-like substrate 207, each of the vacuum vessels 201 to 205 is evacuated by a vacuum pump (not shown), and the internal pressure is reduced to 1 × 10 ⁻⁴ Torr (1.33 × 1
0 ^-4 hPa) or less. As the gate gas, H2 was used, and each of the gate gas introduction pipes 209a to 209a- ₂ was used.
09d was flowed at a flow rate of 700 sccm. Strip-shaped substrate 2
07 is 350 ° C. in each of the heating means 210a to 210c.
Heated.

Next, as a source gas, a gas introduction pipe 211 is used.
a is SiH_Four160 sccm gas, PH_Three/ H
_Two(PH_ThreeConcentration 2%) gas at 120 sccm, H_TwoGas
700 sccm was introduced. Also, the gas introduction pipe 211b
Is SiH_Four100 sccm of gas, H_Two500 s of gas
ccm was introduced. In addition, Si gas is introduced into the gas introduction pipe 211c.
H_Four10 sccm gas, BF_Three/ H_Two(BF_ThreeConcentration 2%)
250 sccm, H _TwoIntroduce 100 sccm of gas
Was. Pressure in vacuum vessels 202 and 204 after introduction of source gas
To 1.02 Torr (1.36 hPa)
The pressure in 203 is 16 mTorr (2.13 Pa)
It was adjusted.

The electric power for plasma generation is 13.56 MHz, 20 μm for the flat plate discharge electrodes 213a and 213b.
0 W of power is applied to the antenna-like discharge electrode 101 by 100
MHz, 700 W power was introduced.

Under the above conditions, a semiconductor layer of the first conductivity type,
The i-type semiconductor layer and the second conductivity type semiconductor layer are sequentially cut to cut a plurality of substrates by cutting the strip-shaped base 207 which is continuously laminated, and a transparent electrode is formed on the second conductivity type semiconductor layer. , ITO (In ₂ O ₃ + SnO ₂ ) by vacuum evaporation
In addition, Al was vapor-deposited by vacuum vapor deposition to a thickness of 2 μm as a current collecting electrode to form a photovoltaic element.

Table 2 shows the conditions for forming the photovoltaic element of Example 1 described above.

[0063]

[Table 2]

(Comparative Example 1) As Comparative Example 1 with respect to Example 1, the source gas introduced when forming the i-type semiconductor layer was not supplied from the antenna-like discharge electrode 101 but to the bottom of the vacuum vessel 210 (band-like substrate). 207) to produce a single-type photovoltaic device. Other conditions are the same as in the first embodiment.

According to Example 1 and Comparative Example 1, each of the band-shaped substrates 207 in which semiconductor layers were continuously laminated
The photovoltaic element of Example 1 and the photovoltaic element of Comparative Example 1, which were cut out at intervals of 5 cm into 5 cm squares, were prepared using AM-1.5
(100 mW / cm ² ), the device was installed under light irradiation, the photoelectric conversion efficiency was measured, and the results of evaluating the change over time and the yield in the process of creating the photoelectric conversion efficiency are shown in Table 3. Here, the uniformity of the photoelectric conversion efficiency, which is a value for evaluating the change over time in the process of creating the characteristics shown in Table 3, is the value of the device of Example 1 and the device of Comparative Example 1 respectively. Of the photovoltaic efficiency of the photovoltaic element of Example 1 was determined for the magnitude of the variation among the plurality of cut-out elements, that is, the magnitude of the change over time in the production process. The values are shown based on the values of the elements.

[0066]

[Table 3]

As shown in Table 3, the photovoltaic element produced in Example 1 was superior to the photovoltaic element produced in Comparative Example 1 in both uniformity of characteristics and high yield. I knew it was.

This means that, in the deposition film formation by the deposition film forming apparatus of the present invention, the semiconductor film is formed with a more uniform deposition rate,
This means that it is possible to deposit with film quality. That is, in forming a deposited film by the deposited film forming apparatus of the present invention, a uniform deposited film is formed not only immediately above the discharge electrode member 101 of the antenna-like discharge electrode 101 but also including a portion away from the antenna-like discharge electrode member 101. I can do this.

(Embodiment 2) In this embodiment, the frequency of the electric power applied when forming the i-type semiconductor layer is changed from 10 MHz to 10 MHz in the single-type photovoltaic device. It was created. Other conditions were the same as in Example 1.

(Comparative Example 2) As Comparative Example 2 with respect to Example 2, similarly to Comparative Example 1, the source gas introduced when forming the i-type semiconductor layer was not supplied from the antenna-like discharge electrode 101 but was applied to a vacuum. The single-type photovoltaic device was produced by discharging from the bottom of the container 210. Other conditions are the same as in Example 2.
Is the same as

The photovoltaic element produced in Example 2 and the photovoltaic element produced in Comparative Example 2 are described in Example 1
Table 4 shows the results of evaluating the characteristic uniformity and the yield in the same manner as in the comparison with Comparative Example 1. The uniformity of the photoelectric conversion efficiency in Table 4 is shown based on the value of the photovoltaic element of Comparative Example 2.

[0072]

[Table 4]

From the results shown in Table 4, it can be seen that even when the frequency of the electric power introduced into the antenna-like discharge electrode 101 is set to 10 MHz, the embodiment in which the present invention is applied to the photovoltaic element prepared in Comparative Example 2 It was found that the photovoltaic element prepared in No. 2 was more excellent in both uniformity of characteristics and high yield.

(Embodiment 3) In this embodiment, the frequency of the electric power applied when forming the i-type semiconductor layer is changed from 750 MHz to 100 MHz in the first embodiment, and It was created. Other conditions were the same as in Example 1.

(Comparative Example 3) As Comparative Example 2 with respect to Example 2, as in Comparative Example 1, the source gas introduced when forming the i-type semiconductor layer was supplied not from the antenna-like discharge electrode 101 but from the vacuum vessel. The single-type photovoltaic device was produced by emitting light from the bottom surface of 210. Other conditions are the same as in the third embodiment.

The photovoltaic element produced in Example 3 and the photovoltaic element produced in Comparative Example 3 are described in Example 1
Table 5 shows the results of evaluating the property uniformity and the yield as in the case of the comparison with Comparative Example 1. The uniformity of the photoelectric conversion efficiency in Table 5 is shown based on the value of the photovoltaic element of Comparative Example 3.

[0077]

[Table 5]

From the results in Table 5, it can be seen that the antenna-like discharge electrode 10
Even when the frequency of the electric power introduced into 1 was set to 750 MHz, the photovoltaic element produced according to Example 3 to which the present invention was applied had more uniform characteristics than the photovoltaic element produced according to Comparative Example 3. It was found that both the properties and the yield were excellent.

Examples 1 to 3 and Comparative Examples 1 to
Based on the results shown in Tables 2 to 4 in comparison with No. 3, the method for introducing the source gas according to the present invention, that is, the method for introducing the source gas from the emission hole 107 provided in the antenna-like discharge electrode 101 is prepared. It has been found that there is an effect of improving the uniformity of the characteristics of the photovoltaic element and increasing the yield, and this effect can be obtained even when the frequency of the high-frequency power to be supplied is changed.

(Embodiment 4) In this embodiment, as compared with the embodiment 1, the hole diameter of the emission hole 107 of the antenna-like discharge electrode 101 is changed to 0.5 mm and the pitch is changed to 12.5 mm, and the A power element was created. The other conditions are the same as in Example 1.
Same as.

The photovoltaic element manufactured according to the present embodiment,
Table 6 shows the results of evaluating the uniformity of the characteristics and the yield with respect to the photovoltaic element prepared in Comparative Example 1 described above, as in the comparison between Example 1 and Comparative Example 1. In addition,
The uniformity of the photoelectric conversion efficiency in Table 6 is shown based on the value of the photovoltaic element of Comparative Example 1.

[0082]

[Table 6]

As shown in Table 6, the photovoltaic element produced in Example 4 was more uniform than the photovoltaic element produced in Comparative Example 1 in terms of uniformity of characteristics and high yield. Was also found to be excellent. Further, as compared with the photovoltaic element manufactured according to Example 1 shown in Table 3, the uniformity of the characteristics and the height of the yield of the photovoltaic element manufactured according to Example 1 were excellent, and the emission hole was improved. 10
It has been found that reducing the hole diameter and pitch of No. 7 is more preferable.

As described above, it was found that the photovoltaic element produced by the production method of the present invention had high uniformity of characteristics and had excellent characteristics, demonstrating the effect of the present invention.

[0085]

As described above, in the method of forming a deposited film according to the present invention, by introducing a raw material gas from the emission hole provided in the antenna-like discharge electrode, the electrode of the antenna-like discharge electrode is formed in the process of forming the semiconductor thin film. A semiconductor film having a uniform deposition rate and a uniform film quality can be supplied not only directly above the member but also in a region apart from the antenna-like electrode member, in a substantially uniform manner, in the vicinity of the surface of the antenna-like discharge electrode. Can be formed.

Also, by using a material having high thermal conductivity for the antenna-like discharge electrode, electric field concentration due to standing waves caused by the wavelength of the high-frequency power, and sudden change in impedance of the power introduction path due to the device structure can be achieved. Local heating of the antenna-like discharge electrode due to electric field concentration at a site or the like can be reduced. Further, by using a metal material having a high melting point as a constituent material of the antenna-like discharge electrode, an antenna-like discharge electrode that is not easily deformed even if discharge is continued for a long time can be obtained.

Thus, according to the deposited film forming apparatus of the present invention, a semiconductor deposited film having excellent uniformity over a large area is formed on the band-shaped substrate while continuously moving the band-shaped substrate. be able to. Therefore, by incorporating this semiconductor deposited film into a semiconductor device, a semiconductor device having high quality and few defects can be formed with higher reproducibility. In particular, by applying the present invention to the production of a photovoltaic element, a large number of photovoltaic elements having high quality and high photoelectric conversion efficiency can be stably produced.

[Brief description of the drawings]

FIG. 1 is a schematic view of a vacuum vessel portion provided with an antenna-like discharge electrode in a deposited film forming apparatus according to an embodiment of the present invention, and FIG. 1A is a cross-sectional view in a horizontal direction, and FIG. )
FIG. 2 is a sectional view taken along line BB of FIG.

2 is a detailed view of an antenna-like discharge electrode portion of FIG. 1, FIG. 2 (a) is a plan view, and FIG. 2 (b) is a sectional view taken along line AA.

FIG. 3 is a schematic view showing an entire deposition film forming apparatus according to an embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 101 Antenna-shaped discharge electrode 102 Conductive electrode support 103 Dielectric 104 Power supply conductor 105 Earth shield 106 Discharge box 107 Emission hole 201, 202, 203, 204, 205 Vacuum container 206 Bobbin 207 Band-shaped substrate 208a, 208b, 208c, 208d Gas gate 209a, 209b, 209c, 209d Gate gas inlet tube 210a, 210b, 210c Heating means 211a, 211b, 211c Gas inlet tube 212a, 212b, 212c Throttle valve 213a, 213b Flat plate discharge electrode

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court ゛ (Reference) H01L 31/04 T (72) Inventor Masahiro Kanai 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. F-term (reference) 4K030 AA06 AA17 BA29 CA02 CA17 EA05 EA06 FA01 FA04 GA14 HA02 JA18 KA12 KA15 KA17 KA30 KA46 LA16 5F045 AA08 AB04 AC01 AC19 AD07 AE17 AF07 BB01 BB08 BB12 BB16 CA03 E15 BA05 E05 AB12A03B BA14 CA07 CA08 CA16 CA22 CA23 CA35 CA36 CA37 DA04 FA04 FA06 FA23 GA02

Claims (18)

[Claims] 1. A source gas is introduced into a vacuum vessel whose inside is kept in a reduced pressure state through a gas introduction pipe, and electric power is introduced to a discharge electrode arranged in the vacuum vessel to cause a discharge. A method of forming a deposited film by a plasma CVD method, comprising the steps of: forming a plasma; and depositing the plasma-converted source gas on a substrate disposed in the vacuum vessel. An antenna-like discharge electrode having a hollow portion connected to the gas introduction pipe and a plurality of discharge holes communicating from the hollow portion to the outside, and providing the raw material gas through the hollow portion through the discharge hole. And forming a deposited film. 2. The raw material gas is supplied to a longitudinal direction of the antenna-shaped discharge electrode by using the antenna-shaped discharge electrode having a rod-like shape and having the emission holes arranged in one or more rows in a longitudinal direction. The method according to claim 1, wherein the introduction is performed substantially uniformly in the direction. 3. The method according to claim 1, wherein the source gas is supplied from the discharge holes arranged in the base over a width exceeding a longitudinal width of the antenna-like discharge electrode over the entire width of the base. 3. The method according to claim 1, wherein the method is substantially uniformly introduced. 4. The source gas is supplied to the entire surface of the deposition film forming surface of the substrate from the emission holes opened in a plurality of directions from the antenna-like discharge electrode toward the deposition film forming surface of the substrate. The method according to any one of claims 1 to 3, wherein the deposition is performed substantially uniformly. 5. The antenna-like discharge electrode is made of a material having a thermal conductivity of at least 70 W / (m · K) at 500 ° C. to reduce local heating of the antenna-like discharge electrode. The method for forming a deposited film according to any one of claims 1 to 4, wherein: 6. The antenna-like discharge electrode is made of one of tungsten, molybdenum and nickel, an alloy containing at least one of these metals, or these metals and alloys for improving various characteristics. 6. The method according to claim 5, wherein the additive is a modified metal or a modified alloy. 7. A gas introduction passage communicating with a hollow portion of the antenna-like discharge electrode and the gas introduction tube, and a power supply conductor is connected, and power from the power supply conductor is supplied to the antenna-like discharge electrode. Providing a conductive electrode support for supporting the antenna-like discharge electrode, which transmits to the discharge electrode, wherein a dielectric is provided in the vacuum vessel so as to surround a connection portion between the antenna-like discharge electrode and the conductive electrode support. An earth shield is provided so as to further surround the dielectric, and when discharging from the antenna-like discharge electrode, preventing discharge at unnecessary places and suppressing a capacitance component of a power introduction path. 7. The method according to claim 1, wherein:
Item 13. The method for forming a deposited film according to Item 1. 8. A belt-like substrate is used as the substrate, and while the belt-like substrate is continuously transported by a transport mechanism so as to pass near the antenna-like discharge electrode, the deposited film is deposited on the belt-like substrate. The method for forming a deposited film according to claim 1, wherein the deposition is performed continuously. 9. The method according to claim 1, wherein the frequency of the electric power introduced into the antenna-like discharge electrode is a VHF frequency of about 30 to 300 MHz. 10. A vacuum vessel for keeping the inside in a reduced pressure state, a gas introduction pipe for introducing a source gas into the vacuum vessel, and an inside of the vacuum vessel for turning the source gas into plasma by electric discharge. A deposition electrode for forming a deposition film on a substrate placed in the vacuum vessel by a plasma CVD method, wherein the discharge electrode is an antenna-like discharge electrode; An apparatus for forming a deposited film, comprising: a hollow portion connected to the gas inlet tube; and a plurality of discharge holes communicating from the hollow portion to the outside. 11. The antenna-like discharge electrode has a rod-like shape, and the emission holes are arranged in one or more rows along the longitudinal direction of the antenna-like discharge electrode. Item 11. A deposited film forming apparatus according to Item 10. 12. The deposition film forming apparatus according to claim 11, wherein the emission holes are arranged over a width of the base in a longitudinal direction of the antenna-like discharge electrode. 13. The deposition according to claim 10, wherein said emission holes are opened in a plurality of directions from said antenna-like discharge electrode toward a deposition film forming surface of said base. Film forming equipment. 14. The antenna-like discharge electrode has a temperature of 500 ° C.
14. The deposited film forming apparatus according to claim 10, wherein the deposited film is made of a material having a thermal conductivity of 70 W / (m · K) or more. 15. The antenna-like discharge electrode is made of one of tungsten, molybdenum, and nickel, an alloy containing at least one of these metals, or an alloy containing these metals or an alloy for improving various characteristics. 15. A modified metal or a modified alloy to which an additive of (1) is added.
3. The deposited film forming apparatus according to item 1. 16. A gas introduction passage communicating with a hollow portion of the antenna-like member and the gas introduction pipe,
A conductive electrode support that is connected to a power supply conductor and transmits power from the power supply conductor to the antenna-like discharge electrode, the conductive electrode support supporting the antenna-like discharge electrode; and the antenna-like discharge electrode in the vacuum vessel. 16. A dielectric disposed so as to surround a connection between the conductive material and the conductive electrode support, and an earth shield disposed so as to further surround the dielectric. Deposition film forming equipment. 17. The substrate according to claim 10, wherein the substrate is a band-shaped substrate, and a transport mechanism for continuously transporting the band-shaped substrate by passing the antenna-shaped discharge electrode near the antenna-shaped discharge electrode. Deposition film forming equipment. 18. The deposition film forming apparatus according to claim 10, wherein the frequency of the power supplied to the antenna-like discharge electrode can be appropriately selected from 13.56 MHz to 2.45 GHz. .