JPH0650734B2 - Thin film manufacturing equipment for amorphous silicon solar cells - Google Patents

Description

TECHNICAL FIELD The present invention relates to an apparatus used for an amorphous silicon solar cell and for producing a thin film by utilizing a high frequency plasma reaction.

[Conventional technology]

FIG. 5 is a partial sectional perspective view of an amorphous silicon solar cell, and generally has a structure in which unit cells are connected in series on one substrate as shown in FIG.
That is, the amorphous silicon solar cell in FIG.
Transparent electrode films 2a, 2b, 2c are formed in a strip shape on a glass substrate 1, and amorphous silicon films 3a, 3b, 3c, which are photovoltaic generators, are formed on these, and a metal electrode film is further formed thereon. 4a, 4b, 4c are formed so as to be sequentially stacked. For example, the transparent electrode film 2b of a unit cell is electrically connected to the transparent electrode films 2a, 2c of adjacent unit cells.

Regarding each thin film constituting this solar cell, the transparent electrode films 2a, 2b and 2c are formed by the thermal CVD method and the amorphous silicon film 3
a, 3b and 3c are plasma CVD method, metal electrode film 4a,
4b and 4c are formed by a vapor deposition method, a sputtering method, a printing method or the like. In order to configure each of these thin films as shown in FIG. Is normal.

Here, the amorphous silicon thin films 3a, 3b, 3c of the solar cell
A plasma CVD apparatus used for forming the film will be outlined. FIG. 6 is a cross-sectional view of an essential part showing the structure of the apparatus, and the main constituent parts of this apparatus are an exhaust system 6 for evacuating the reaction container 5 and the reaction container 5 to supply a film forming gas into the reaction container 5. Gas supply system 7, cathode electrode 8, anode electrode 9, RF power source 10 connected to cathode electrode 8, glass substrate 11 located on anode electrode 9, heater located below anode electrode 9 and heating substrate 11 12 and heater power supply 13. In the case of a solar cell, the above-mentioned transparent electrodes 2a, 2b, 2c are already formed on the glass substrate 11, but the illustration thereof is omitted here.

In order to form an amorphous silicon thin film on the glass substrate 11 using the above apparatus, the reaction vessel 5 is first evacuated by the vacuum evacuation system 6 to a degree of vacuum of about several mtorr or less, and then the gas is removed. Si containing SiH ₄ or H ₂ from the supply system 7
A film forming gas such as H ₄ is supplied into the reaction vessel 5 and is partially evacuated by the vacuum exhaust system 6 to maintain the pressure in the reaction vessel 5 at about 1 torr. After that, electric power is supplied from the RF power source 10 to the cathode electrode 8 and the anode electrode 9 to generate plasma between the electrodes 8 and 9. At this time, about 20 by the heater 12 by the power supply 13
The substrate 11 on the anode electrode 9 heated to 0 ° C.
By the plasma generated between both electrodes 8 and 9, an amorphous silicon thin film not shown in FIG. 6 can be formed thereon.

After forming the amorphous silicon thin film in this way, a part of it is cut by a laser or the like, and further, the steps of depositing and processing a metal electrode and finally the amorphous silicon solar cell shown in FIG. It becomes.

[Problems to be Solved by the Invention]

Plasma C for forming the amorphous silicon film of the solar cell
Although the apparatus using the VD method has been described, in principle, even if the above-mentioned apparatus can be used for a thin film apparatus, in actuality, the substrate area is increased or electrodes are formed in one reaction container in order to improve mass productivity. It is also practiced to arrange multiple substrates. However, if this is done, the reaction container, which is a vacuum container, must be made larger, and as a result, the structure for providing the pressure resistance required for the reaction container and the auxiliary equipment for increasing the gas exhaust capacity become large. However, the cost of the device will be high, and it will not always be possible to improve the mass productivity and reduce the manufacturing cost of the solar cell. Furthermore, in the above apparatus, amorphous silicon as a reaction by-product adheres to the wall surface of the reaction container in a cotton shape during film formation,
Since this impairs the characteristics of the solar cell, it is necessary to remove this adhering substance, and it is necessary to regularly clean the inside of the reaction container, which causes a problem of lowering the operation rate of the apparatus.

The present invention has been made in view of the above points, and an object thereof is to provide a thin-film manufacturing apparatus for an amorphous silicon solar cell, which has a large effect of mass production and can be operated efficiently.

[Means for Solving the Problems]

In order to achieve the above object, the thin film manufacturing apparatus for an amorphous silicon solar cell of the present invention uses a glass substrate for forming a thin film, instead of a reaction container which is a conventional vacuum container, and has a plurality of frameworks. A space surrounded by two glass substrates is formed with a support interposed, and this is used as a plasma decomposition chamber, and gas is exhausted from one end of the framework and a film forming gas is introduced from the other end of the frame. RF power is applied by the cathode electrode arranged in the middle or one of the plasma decomposition chambers and the two anode electrodes arranged near the outer peripheral surface of the plasma decomposition chamber to cause plasma decomposition and to be provided around the anode electrode. The heater is used to heat the glass substrate, and the apparatus is used to form the transparent electrode film and the amorphous silicon film by the decomposition of the film-forming gas on the glass substrate which is the inner wall surface of the plasma decomposition chamber. Are those that form.

[Action]

As described above, since the thin film manufacturing apparatus of the present invention is configured such that the glass substrate itself on which the thin film is formed becomes the inner wall surface of the plasma decomposition chamber, even if the area of the thin film increases, a large reaction container or No additional equipment is required, and the support placed inside the plasma decomposition chamber prevents the glass substrate from being deformed or damaged even when the pressure inside the plasma decomposition chamber is reduced. Plays a role of reinforcement,
Since this support does not form a thin film where it contacts the glass substrate, it also functions as a mask. Conventionally, when forming the transparent electrode film and the amorphous silicon film, post-processing was performed for selective removal. By defining the contact position between the support and the glass substrate at a position, it is possible to arrange these thin films generated by the decomposition of the film forming gas in a strip shape at a desired position without post-processing.

〔Example〕

 The present invention will be described below based on examples.

FIGS. 1 and 2 show the structure of a thin film manufacturing apparatus for an amorphous silicon solar cell according to the present invention. FIG. 1 is a cross-sectional view showing the entire main structure of the present invention, and FIG. It is a cross-sectional perspective view. A description will be given below with reference to FIGS. 1 and 2 together.

First, in FIG. 1, this apparatus has a cathode electrode 15 connected to an RF power source 14 and two anode electrodes 16 arranged in parallel on both sides of the cathode electrode 15 at a predetermined interval, and two electrodes are provided in a gap formed between these electrodes. The plasma decomposition chambers 17 are kept in mutual positions so that they are inserted. Plasma decomposition chamber 17
The two frame substrates 18 and 2 are formed by bringing two glass substrates 19 into contact with the opening surface of the long-side frame 18 which is open in the width direction via a sealing material (not shown in FIG. 1). It is a space portion surrounded by one glass substrate 19. The cathode electrode 15, the anode electrode 16 and the two plasma decomposition chambers 17 are arranged vertically long and parallel to each other so as to maintain a predetermined gap. A plurality of gas introduction pipes 20 for introducing a film forming gas are attached to the upper sides of the frame 18 which face each other, a plurality of gas exhaust pipes 21 are attached to the lower side thereof, and each of the plasma decomposition chambers 17 has an internal structure shown in FIG. In FIG. 2, a plurality of supports (not shown) are inserted, and in order to clarify the relationship between them, a partial cross-sectional perspective view is shown and the same reference numerals are used in common with FIG. In FIG. 2, the two glass substrates 19 are in close contact with a sealing material 22 such as an O-ring fitted in a groove of the opening surface of the frame body 18 made of stainless steel, for example, but one glass substrate is shown in FIG. Was omitted. Inside the plasma decomposition chamber 17, a plurality of supports 23, such as ceramic plates, which come into contact with the inner surfaces of the frame 18 and the glass substrate 19 on all sides are provided in a predetermined direction in the vertical direction of the plasma decomposition chamber 17 shown in FIG. A plurality of gas introduction pipes 20 for introducing the film forming gas into the upper side of the frame 18 of each of the plurality of regions partitioned at intervals, and gas introduction into the lower side of the frame 18 as shown in FIG. Although a plurality of gas exhaust pipes 21 for exhausting a part of the film-forming gas are attached to the pipes 20, the gas exhaust pipes 21 are not shown in FIG. These gas introduction pipes 20 are connected to each other to a gas supply system (not shown), and also connected to a gas exhaust pipe 21 to be guided to a vacuum exhaust system (not shown). Plasma decomposition chamber 17
When the frame is evacuated by the gas exhaust pipe 21, the frame 1
It is vacuum-sealed by the sealing material 22 between the eight and two glass substrates 19, so that the glass substrate 19 and the frame 18 can be kept airtight. Further, the heaters 24 for heating the respective glass substrates 19 are provided in the vicinity of the two anode electrodes 16 along these electrodes, respectively, as shown in FIG.

The structure of the thin film manufacturing apparatus of the present invention has been described above.
Next, a procedure for assembling the plasma decomposition chamber 17 will be described. First, the two frameworks 18 to which the gas introduction pipe 20 and the gas discharge pipe 21 are attached are set upright in a vertically long direction as shown in FIG. 1, and the required number of the supports 23 is set to a predetermined number from the opening surface of each framework 18. Insert in position. Each of the support members 23 needs to have a dimensional accuracy such that both end surfaces are held by sliding on the facing inner surfaces of the framework 18. Next, the two glass substrates 19 are put on the sealing material 22 fitted in the opening surface grooves on both sides of each frame 18, and the frame 18 is sandwiched. In this state, the two glass substrates 19 and the frame 18 are formed. Each of the two plasma decomposition chambers 17 holds each glass substrate 19 by using an appropriate number of clamps at appropriate positions. Subsequently, these two plasma decomposition chambers 17 are inserted into the gap between the fixed cathode electrode 15 and the two anode electrodes 16, and then the gas cormorant supply pipes 20 attached to each plasma decomposition chamber 17 are connected and gas is exhausted. The pipe 21 is connected, and further connected to the gas supply system of the apparatus main body and the vacuum gas generation system. These connections can be easily made by using the pipe joint member. Thus, by performing vacuum evacuation, the inside of each plasma decomposition chamber composed of the glass substrate 19 and the frame 18 is decompressed, and the glass substrate 19 can be kept airtight with the frame 18 via the sealing material 22. At this point, an appropriate number of clamps for pressing the glass substrate 19 used previously is unnecessary, so all of them are removed.

Although the plasma decomposition chamber 17 can be assembled as described above, when the plasma decomposition chamber 17 is evacuated,
Since a pressure of 1 kg / cm ² is externally applied to the glass substrate 19 forming the wall surface, if this exceeds the strength of the glass, the glass substrate 19 will be damaged. Support 23
Prevents the glass substrate 19 from being deformed or damaged against the external pressure in such a case, and this is the first effect of the support member 23. Glass substrate 1 with a thickness of 3 mm
The glass substrate 19 can be prevented from being damaged by inserting the support member 23 at an interval of 3 cm with respect to 9.

Next, a process of forming a thin film of an amorphous silicon solar cell using the apparatus of the present invention will be described. First, each plasma decomposition chamber 17
Is evacuated to about several mTorr or less by a vacuum device (not shown) connected to the gas discharge pipe 21, and then the film-forming gas is supplied from the gas introduction pipe 20 to the plasma decomposition chamber 17 by a gas supply system (not shown). And a part of the gas is exhausted through the gas exhaust pipe 21 to keep the plasma decomposition chamber 17 at a pressure of about 1 Torr. After this, the cathode electrode 15 and the anode electrode 1
High-frequency power is applied from the RF power source 14 to the plasma generator 6 to generate plasma of the film forming gas inside the plasma decomposition chamber 17, which is used as a wall surface of the plasma decomposition chamber 17 and is heated to about 200 ° C. by the heater 24. A thin film can be formed on the substrate 19 by decomposition of the film forming gas. This situation will be described with reference to FIG. FIG. 3 is a partial cross-sectional view showing the positional relationship between the glass substrate 19 and the support member 23, in which transparent electrode films 25a, 25b, 25c and amorphous silicon films 26a, 26b, 26c are sequentially formed. Is shown. FIG. 3 (a) shows the initial state of the glass substrate 19 and the support 23 that supports it. First, as the above-mentioned film forming gas, (CH ₃ ) ₄ Sn, N ₂ , O ₂ , CF ₃ When Br was flown at a ratio of 1: 10: 10: 0.1, the transparent electrode film S
nO ₂ : F 25a, 25b, 25c are formed as shown in FIG. 3 (b). These transparent electrode films 25a, 25b, 25c
Each of them has a characteristic value of 5 Ω / □ at a thickness of 1 μm, and has a strip shape divided by the support member 23. Next, the pressure in the plasma decomposition chamber 17 is increased to such an extent that the glass substrate 19 can be moved in parallel, so that the position of the glass substrate 19 is 0.1 to 1 m.
Shift about m as shown in Fig. 3 (c). At this time, since the thickness of each transparent electrode film is about 1 μm, it is easy to shift the glass substrate 19. The plasma decomposition chamber 17 is again set to 1 Torr.
Then, the pressure is set to about 10% SiH ₄ (H ₂ dilution), 0.1% B ₂ H ₆ (H ₂ ) for the P-type amorphous silicon film.
_{Dilution), 1% C 4 H 2} (H 2 dilution), i Katachihi 10% SiH _{4 (H 2} dilution for Si film), n Katachihi amorphous silicon film for the 10% SiH _{4 (H 2} Dilution) and 0.1% pH ₃ (H ₂ dilution) are sequentially supplied to cause plasma decomposition to form the P-type-i-n-type amorphous silicon films 26a, 26b, and 26c in FIG. 3 (d). Can be formed in a laminated manner. In this case, the values of gas composition, temperature, film thickness of each layer, etc. may be the same as usual ones. By finally forming a metal electrode film,
An amorphous silicon solar cell having the same structure as the fifth one can be obtained. Even though the basic structure is the same, the amorphous silicon solar cell manufactured by using the apparatus of the present invention is different from the conventional one in that the transparent electrode films 25a, 25b, 25c and the amorphous silicon films 26a, 26b are different. , 26c does not require post-processing such as laser processing. That is, in the apparatus of the present invention, the support 23 is provided in the plasma decomposition chamber 17, and when the high frequency power is supplied from the plasma decomposition chamber 17 to form a thin film, the support 23 is formed.
Serves as a mask, and a strip-shaped thin film is formed on the glass substrate 19 without forming a thin film on the contact portion between the glass substrate 19 and the support member 23. Therefore, at the place where the groove processing of the thin film was performed in the past,
By positioning the support member 23 so that the glass substrate 19 and the support member 23 are in contact with each other, the thin film processing step can be eliminated. This is the second effect of the support 23.

As described above with reference to FIGS. 1 and 2, the thin film manufacturing apparatus for an amorphous silicon solar cell according to the present invention has a transparent electrode film and an amorphous silicon film on four glass substrates without post-processing. Although this is a highly efficient device capable of continuously forming a film, as can be seen from FIG. 1, the temperature of the glass substrate 19 is close to the heater 24 on the side of the anode electrode 16 and the heater 2.
4, the uniformity becomes slightly worse on the side of the cathode electrode 15 farther away from the cathode electrode 4, and the thin film formed on the glass substrate 19 on the side of the anode electrode 16 and the glass substrate 19 on the side of the cathode electrode 15
There may be a case where the film quality is slightly different from that of the thin film formed in 1. To solve this, only one plasma decomposition chamber is used, and the cathode electrode may be arranged inside this plasma decomposition chamber.

The relationship between the cathode electrode and the support in the plasma decomposition chamber at this time is shown in the partial cross-sectional perspective view of FIG. Figure 4 is second
It is a partial cross-section perspective view of the same plasma decomposition chamber 17a as the figure, and the same code | symbol is used for the same part as FIG. 4 is different from FIG. 2 in that a lattice-shaped cathode electrode 15a is provided in parallel with the glass substrate 19 in the plasma decomposition chamber 17a, and the position where the cathode electrode 15a intersects with the plurality of supports 27 is somehow. Also, a through hole 28 is opened in the support body 27, and the cathode electrode 15a is supported through the through hole 28.
It is connected to a portion that does not intersect with in a lattice shape, and one end thereof is connected to an RF power source (not shown) through a hermetic seal 29 attached to the frame 18. The other parts are the same as in the case of FIG. The method of assembling the plasma decomposition chamber is almost the same as that described above. In this case, the cathode electrodes 15a in the form of a grid are formed in advance through the through holes 28 of the plurality of supports 27, The only difference is that this is inserted into the framework 18 and one end of the cathode electrode 15a is connected to the hermetic seal 29.

In this way, the cathode electrode 15a is connected to the plasma decomposition chamber 17a.
Since the cathode electrode 15a has a lattice shape, the formed thin film has high uniformity. Further, in this case, since the anode electrode and the heater are arranged on both sides of one plasma decomposition chamber 17a, the uniformity of the temperature rising with respect to the glass substrate is improved, but since only two glass substrates 19 are used, the first
Productivity is inferior to that in the figure.

The manufacturing process of the transparent electrode film and the amorphous silicon film, the effect of the support, and the like are the same as those described above, and thus the description thereof is omitted.

〔The invention's effect〕

Amorphous silicon solar cell thin film manufacturing equipment requires a large reaction vessel in order to improve the mass production effect, and post processing is inevitable every time thin film formation is performed, which requires a large amount of equipment and man-hours. In the apparatus of the present invention, as described in the embodiment, the plasma decomposition chamber composed of the frame and the glass substrate is used to form a thin film on the glass substrate which is the inner wall surface of the plasma decomposition chamber, so that the apparatus is compact. In addition to being capable of handling a large area of amorphous silicon solar cells, a plurality of supports provided in the plasma decomposition chamber prevent deformation and damage of the glass substrate. Since it also has a role as a mask during thin film formation, a strip-shaped thin film is formed on the glass substrate without post-processing, and the work of removing the by-products that occur during conventional film formation is not required, and the number of manufacturing steps is short. Improvement of the operating rate is remarkable. That is, when an amorphous silicon solar cell is manufactured using the device of the present invention, the entire device becomes compact and the equipment cost is reduced, and the transparent electrode film and the amorphous silicon film are post-processed on the glass substrate. It is possible to obtain the extremely large effect that the processing cost is reduced without being formed continuously.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a main part of the apparatus of the present invention, FIG. 2 is a partial cross-sectional perspective view of the apparatus of the present invention, and FIG. 3 is a partial cross-sectional view showing a film forming process by the apparatus of the present invention. Is a partial cross-sectional perspective view when the cathode electrode in the device of the present invention is provided inside the plasma decomposition chamber, FIG. 5 is a cross-sectional view of a main part showing the structure of an amorphous silicon solar cell, and FIG. It is a principal part composition sectional view. 1, 11, 19 ... Glass substrate, 2a, 2b, 2c, 2
5a, 25b, 25c ... Transparent electrode film, 3a, 3b, 3
c, 26a, 26b, 26c ... Amorphous silicon film, 5
...... Reaction container, 8, 15, 15a …… Cathode electrode
9,16 ... Anode electrode, 10,14 ... RF power supply,
12, 24 ... Heater, 17, 17a ... Plasma decomposition chamber, 18 ... Framework, 20 ... Gas introduction pipe, 21 ... Gas discharge pipe, 22 ... Sealing material, 23, 27 ... Support, 2
8 ... through hole, 29 ... hermetic seal.

Claims (2)

[Claims] 1. A thin film manufacturing apparatus for an amorphous silicon solar cell using a plasma CVD method, comprising: a. A rectangular framework that opens in the width direction, two glass substrates that are in close contact with each other on both opening surfaces of the framework via a sealing material, and this space inside the box-shaped space surrounded by these glass substrates and the framework. A plasma decomposition chamber composed of a plurality of supports, each of which has one parallel end face in parallel contact with each glass substrate so as to be divided into a plurality of predetermined regions, and the other parallel end faces contact the inner surface of the frame, respectively. b. Corresponding to a plurality of gas supply pipes mounted so as to connect two plasma decomposition chambers to each other in one of the facing frames of the regions divided by the support of the plasma decomposition chamber and the gas supply pipe mounted to the other A plurality of gas exhaust pipes, c. A cathode electrode connected to an RF power source, which is located between two plasma decomposition chambers arranged in parallel at a predetermined interval and is opposed to the glass substrate of each plasma decomposition chamber on both sides, and another of the plasma decomposition chambers. Two anode electrodes disposed so as to face the outer peripheral surface of one of the glass substrates, d. Thin film production of an amorphous silicon solar cell, characterized by comprising two heaters respectively arranged near the two anode electrodes and heating two glass substrates for plasma decomposition chambers via these anode electrodes. apparatus. 2. A thin film manufacturing apparatus for an amorphous silicon solar cell using a plasma CVD method, comprising: a. A rectangular framework that opens in the width direction, two glass substrates that are in close contact with each other on both opening surfaces of the framework via a sealing material, and this space inside the box-shaped space surrounded by these glass substrates and the framework. A plurality of support bodies in which one parallel end face is in contact with each glass substrate in parallel vertically so as to be divided into a plurality of predetermined regions, and the other parallel end faces are in contact with the inner surface of the frame, respectively, and glass in the space is provided. A plasma decomposition chamber, which is assembled in parallel with the substrate in a lattice shape and is connected to each other through a plurality of through holes provided in each support, and one end of which is a cathode electrode connected to an RF power source, b. A plurality of gas supply pipes attached to one of the frames facing each other of the regions of the plasma decomposition chamber divided by the supports and a plurality of gas discharge pipes corresponding to the gas supply pipes attached to the other; c. Two anode electrodes arranged so as to face both outer peripheral surfaces of the two glass substrates of the plasma decomposition chamber, d. An apparatus for manufacturing a thin film of an amorphous silicon solar cell, comprising two heaters which are respectively disposed in the vicinity of two anode electrodes and heat the glass substrate of the plasma decomposition chamber via these anode electrodes.