JPH06224140A - Manufacture of silicon laminate - Google Patents

Abstract

PURPOSE:To provide a silicon laminate manufacturing method wherein a polycrystalline silicon film which is very thin, large in crystal grain diameter, and hardly separated off from a substrate can be formed in a short time. CONSTITUTION:A carbon fiber woven cloth 21 (carbon base material) is heated at a temperature of 1400 deg.C, a mixed gas of silane, methane, and phosphine (N-type dopant) is fed and made to react with each other in vapor on the woven cloth 21, whereby a N-type dopant-loaded intermediate film 22 of silicon carbide uniform in thickness and quality is formed on the cloth 21, silicon particles are introduced into plasma of high temperature to be fused, the fused silicon particles are turned into a polycrystalline silicon film 23 large in crystal grain diameter on the intermediate film 22, and thus a silicon laminate 20 composed of a woven cloth, an intermediate film, and a polycrystalline silicon film is manufactured. A polycrystalline silicon film can be lessened in film stress by the action of an intermediate film, and furthermore a woven cloth and a polycrystalline silicon film can be ohmically joined together, so that a BSF effect can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carbon-based base material and a polycrystalline silicon film formed on the base material, the main part of which is composed of, for example, a silicon layer forming a part of a solar cell. And a silicon laminate that can be integrally applied as a back surface electrode member, and in particular, a wide selection range of applicable silicon raw materials, a thin film that does not easily peel from the base material, and a large crystal grain size thereof. The present invention relates to a method for manufacturing a silicon laminate, which can form a crystalline silicon film in a short time.

[0002]

2. Description of the Related Art As a method for producing a silicon laminate of this kind using a carbon-based material, for example, Japanese Patent Laid-Open No. 55-73 is used.
The one described in Japanese Patent Publication No. 450 is known.

That is, in this manufacturing method, a carbon fiber woven cloth having a net-like structure having a series of holes is dipped in the melted silicon contained in the melting tank, and the melted silicon is filled in and inside the holes. The silicon laminate manufactured by the method of coating and crystallizing this melt to obtain a silicon laminate is, for example, integrated with the silicon layer of the solar cell shown in FIG. Has been applied.

In FIG. 5, a is a p-type silicon layer and b is n.
A type silicon layer, c is an antireflection layer such as ITO, d is a comb-shaped electrode, e is an ohmic contact layer, and f is a backside electrode.

By the way, when a silicon laminate is manufactured by this method, it is premised that a carbon fiber woven fabric having a net-like structure having a series of holes for holding and crystallizing the molten silicon is applied. In this manufacturing method, there is a drawback that it is difficult to apply a sheet-like base material whose surface and internal structure are in a dense state, and the base material such as the carbon fiber woven cloth has holes. Since the electric resistance becomes large, there is a drawback that it is difficult to improve the photoelectric conversion efficiency of the incorporated solar cell.

Therefore, in the past, the thermal CV is usually used.
A method is adopted in which a polycrystalline silicon film is directly formed on a carbon-based substrate surface by a film forming means such as D method or plasma CVD method to manufacture a silicon laminated body, and the silicon laminated body is incorporated into the solar cell or the like. ing.

[0007]

However, the latter silicon laminated body manufactured by applying the above-mentioned film forming means also has the following problems.

That is, thermal CVD is performed on the surface of the carbon-based substrate.
When a polycrystalline silicon film is formed by a method such as a method, there is a drawback that stress tends to occur in the formed polycrystalline silicon film due to the difference in thermal expansion coefficient between the carbon-based base material and silicon. Unless the thickness of the crystalline silicon film is set to a certain degree, defects and cracks are likely to occur in the film, and the film stress easily causes the polycrystalline silicon film to peel off from the carbon-based substrate. There was a point.

Also in the method of forming a polycrystalline silicon film itself, a silane compound such as SiH ₄ , Si ₂ H ₆ or SiH ₂ Cl ₂ which can easily decompose the silicon raw material applicable to this method in the thermal CVD method, or SiH ₂ Cl ₂ , Limited to silicon halides such as SiHCl ₃ , SiF ₄ , SiCl ₄ , Si ₂ F ₆ ,
Also, it is difficult to decompose silicon halide such as SiH ₂ F ₂ or metal grade silicon particles (MG / Si) that have not been sufficiently purified.
However, the material selection range is narrow because it is difficult to apply, and even if the above silane compounds such as SiH ₄ are applied, the decomposition rate is not so high, and the material supply rate to the substrate is correspondingly high. However, there is a problem in that it takes a long time to form a film of polycrystalline silicon because of slowing down.

On the other hand, the plasma CVD method has a drawback that the selection range of applicable materials is narrow, and the decomposition rate of silicon raw material is low, so that it takes time to form a polycrystalline silicon film as in the thermal CVD method. was there. Further, the plasma CVD method has an advantage that the substrate is not required to have heat resistance because it is performed under a low temperature condition, but on the other hand, since the film forming process is performed at a low temperature, polycrystalline silicon having a large crystal grain size is used. There was a problem that the film was difficult to obtain.

Under such a technical background, the present inventors have made use of a carbon-based substrate such as carbon fiber and silicon carbide formed on the surface of the carbon-based substrate and mixed with an n-type or p-type dopant. We have already created a silicon laminated body in which the main part of the intermediate film is a polycrystalline silicon film formed on this intermediate film.

According to this silicon laminate, an intermediate film made of silicon carbide having an intermediate property between carbon and silicon chemically and physically is provided between the carbon-based substrate and the polycrystalline silicon film. Since it is interposed, the chemical affinity between the carbon-based base material and the polycrystalline silicon film can be improved, and the film stress can be reduced immediately after the polycrystalline silicon film is formed. Since the n-type or p-type dopant is mixed in the intermediate film, it becomes possible to form an ohmic contact between the carbon-based substrate and the polycrystalline silicon film, and the n-type or p-type is formed.
By the action of the type dopant, the electrical resistance of the intermediate film made of silicon carbide can be lowered, and an electric field is generated in the polycrystalline silicon film, so that the BSF effect can be obtained.

Therefore, an object of the present invention is to provide a manufacturing method capable of mass-producing such a silicon laminate easily and economically.

[0014]

That is, the invention according to claim 1 is an intermediate product comprising a carbon-based base material and silicon carbide formed on the surface of the carbon-based base material and mixed with an n-type or p-type dopant. Assuming a method for manufacturing a silicon laminated body composed of a film and a polycrystalline silicon film formed on this intermediate film, gaseous silicon is used for a carbon-based base material set at a temperature just below the melting point of silicon. A mixed gas composed of a raw material, a carbon raw material, and an n-type or p-type dopant gas is supplied,
After reacting this mixed gas on the carbon-based substrate to form an intermediate film made of silicon carbide mixed with an n-type or p-type dopant, a silicon raw material containing silicon atoms is introduced into high temperature plasma. Characterized in that the raw material is melted or decomposed, and the melted or decomposed material is formed on an intermediate film of a carbon-based substrate whose temperature is set just below the melting point of silicon to form a polycrystalline silicon film. It is a thing.

The invention according to claim 1 will be described below in detail with reference to the drawings.

First, as an apparatus applied to this manufacturing method, as shown in FIG. 2, a high temperature plasma generating section 1 for generating high temperature plasma of several thousands to 10,000 degrees, and a high temperature plasma generating section 1 are adjacent to the high temperature plasma generating section 1. And a reaction chamber 3 in which the carbon-based base material 2 is disposed, and the main part thereof is configured, and gaseous silicon is supplied to the carbon-based base material 2 set to a temperature just below the melting point (1430 ° C.) of silicon. A mixed gas composed of a raw material, a carbon raw material, and an n-type or p-type dopant gas is supplied,
Silicon carbide (SiC) in which an n-type or p-type dopant is mixed by reacting this mixed gas on the carbon-based substrate 2
After the formation of an intermediate film consisting of the above, the silicon raw material introduced into the high temperature plasma generating part 1 and melted or decomposed is formed on the intermediate film of the carbon-based substrate 2 which is set at a temperature just below the melting point of silicon. Then, a polycrystalline silicon film is formed.

An exhaust system 4 is provided on the downstream side of the reaction chamber 3 so as to discharge volatile components contained in the silicon raw material and silicon not deposited on the carbon-based substrate 2. Is configured. Further, in FIG. 2, 5 is a container for containing silicon particles 6 as a silicon raw material, 7 is a base material holder for holding the carbon-based base material 2, and 8 is a heating means provided in the base material holder 7. Shown respectively.

Here, as the means for generating the above-mentioned high temperature plasma, there are a direct current method using arc plasma, a high frequency method using induction plasma, and a combination method using both arc plasma and induction plasma. The method can also be applied.

That is, in the DC method, as shown in FIG. 3, an arc discharge is generated between the electrode portion 11 and the cathode portion 12 of the DC plasma torch 16, and the arc discharge flows between the electrode portion 11 and the cathode portion 12. Argon gas, hydrogen gas, etc. are decomposed to generate high temperature plasma. Then, a silicon raw material is introduced into a portion where high-temperature plasma is generated, the silicon raw material is melted and decomposed by high-temperature argon plasma, hydrogen plasma, etc., and the molten or decomposed product is transported to the carbon-based substrate 2 side. Then, a polycrystalline silicon film is formed. On the other hand, in the high frequency method, as shown in FIG. 4, an RF plasma coil 14 is provided at the center of a quartz tube 13 to which argon gas, hydrogen gas, etc. are supplied.
The plasma frame 15 is formed by winding RF coil and generating induction plasma by the RF plasma coil 14 and is wider than the DC method. The combined method is a combination of the direct current method and the high frequency method (see FIG. 2).

The shape of the plasma frame 15 and the melting of the silicon raw material are adjusted by appropriately adjusting the input power of direct current or high frequency, the flow rate of argon gas, hydrogen gas, etc., the input amount of the silicon raw material and the type thereof described below. Alternatively, since it becomes possible to control the decomposition state, the concentration of the silicon component contained in the melted or decomposed product, the flow rate thereof, etc., the film forming conditions for the polycrystalline silicon film can be determined by appropriately selecting these conditions. It becomes possible to adjust.

The pressure condition in the high temperature plasma generating section 1 is usually large in consideration of the ease of supplying the silicon raw material into the high temperature plasma generating section 1 and the simplification of the structure of the manufacturing apparatus. The condition is set to atmospheric pressure or near atmospheric pressure (several hundred Torr), but lower condition, for example, several tens T
Of course, it may be set to orr. When the pressure condition in the high temperature plasma generation unit 1 is set to be low as described above, the plasma flame 15 (plasma space)
As a result, the melting or decomposition product of the silicon raw material can be supplied to a wide region of the carbon-based substrate 2, and an advantage that a large-area and uniform-quality polycrystalline silicon film can be formed on the carbon-based substrate 2. have. However, since the plasma space expands and the amount of energy supplied per unit volume thereof decreases, it is necessary to increase the input power of direct current or high frequency. Moreover, when the pressure condition in the high temperature plasma generation part 1 is set low, the plasma flame 15 may expand and the carbon-based base material 2 may be overheated. In such a case, the above-mentioned overheating phenomenon can be easily avoided by reducing the flow rates of argon gas, hydrogen gas and the like.

Next, as the carbon-based substrate applicable in the invention according to claim 1, a graphite plate or a carbon-carbon composite material (for example, carbon fiber and carbonized resin) having a dense surface and internal structure is used. Components, etc.), and carbon fiber woven fabrics in which the surface and the internal structure are densely knitted in a dense state, and the like. The application of fiber woven cloth is also possible.

Further, for example, SiH ₄ , Si ₂ H ₆ or the like can be applied as the gaseous silicon raw material constituting the above mixed gas, and CH ₄ , C ₂ H ₆ , and C can be used as the gaseous carbon raw material. Saturated hydrocarbons such as ₃ H ₈ and unsaturated hydrocarbons such as ethylene and acetylene can be applied. As the n-type dopant gas, PH ₃ (phosphine) gas, AsH is used.
₃ (arsine) gas or the like, and as the p-type dopant gas, B ₂ H ₆ (diborane) gas, B (CH ₃ ) ₃ (trimethylboron) gas, or the like can be used.

Then, the mixing ratio of the silicon raw material, the carbon raw material, and the n-type or p-type dopant gas and the supply amount thereof are appropriately adjusted, and the mixed gas is subjected to a gas phase reaction on the carbon-based base material. It is possible to form an intermediate film made of silicon carbide (SiC), which is a thin film in which an n-type or p-type dopant is mixed, and whose film thickness and film quality are uniform, on a carbon-based substrate.

On the other hand, as a silicon raw material which is introduced into the high temperature plasma to form a polycrystalline silicon film, silane compounds such as SiH ₄ and Si ₂ H _{6 which} are easily decomposed, Si
Silicon halides such as H ₂ Cl ₂ and SiHCl ₃ can be applied, and SiF ₄ , SiCl ₄ , Si ₂ F ₆ and Si _{2 can be used.}
Cl ₆ , SiH _x F _y , SiH _x Cl _y, or other gas or liquid silicon halide that is difficult to decompose can be applied, and further, the purification treatment is insufficient and the particle size of the metal-grade silicon is about 200 μm or less. Particles (MG / Si, for example, having a Si purity of 99%) and purified solar cell grade silicon particles (SOG, for example, a Si purity of 99.9999%)
It is also applicable to powders containing silicon atoms such as those) because impurities contained in these silicon particles are easily removed as volatile components by high temperature heat treatment.

When metal-grade silicon particles are applied,
Oxygen (O ₂ ) gas and water vapor (H ₂ O) to remove light elements such as B (boron) and C (carbon) contained in the particles
Etc. may be supplied to the high temperature plasma, or fluorides such as calcium fluoride (CaF ₂ ) may be added to the high temperature plasma in order to remove heavy metals such as Ti (titanium) and Fe (iron) contained in the particles. You may supply in plasma. In addition, a pressure control valve may be provided to prevent the pressure in the reaction chamber from fluctuating when the silicon raw material is charged and to keep the pressure in the reaction chamber substantially constant.

Then, a mixed gas composed of a gaseous silicon raw material, a carbon raw material, and an n-type or p-type dopant gas is supplied to the carbon-based base material set to a temperature just below the melting point of silicon. The mixed gas is subjected to a gas phase reaction on the carbon-based base material to form an intermediate film of silicon carbide having an intermediate property between carbon and silicon and having an n-type or p-type dopant mixed therein. In this case, in this manufacturing method, the mixed gas is supplied from the outside and the mixed gas is subjected to a gas phase reaction on the carbon-based substrate to form an intermediate film of silicon carbide (SiC). By properly controlling the mixing ratio of the mixed gas and the supply amount thereof, it is possible to reliably form an intermediate film which is a thin film in which an n-type or p-type dopant is mixed on a carbon-based substrate and whose film thickness and film quality are uniform. Have advantages.

Next, after the intermediate film is formed, a molten or decomposed product of the silicon raw material is formed on the intermediate film of the carbon-based base material set at a temperature just below the melting point of silicon to form a polycrystalline silicon film. Form. In this case, since the polycrystalline silicon film is formed in a state in which the carbon-based base material is set to the temperature just below the melting point of silicon, the difference between the polycrystalline silicon film temperature immediately after the formation and the carbon-based base material temperature. Becomes smaller, and the film stress of the polycrystalline silicon film is reduced accordingly, and the film stress can be further reduced by the action of the silicon carbide intermediate film having an intermediate property between carbon and silicon. Therefore,
Even if the film thickness is set to be small, there is an advantage that defects and cracks are less likely to occur in the formed polycrystalline silicon film, and peeling from the carbon-based substrate is less likely to occur.

In the manufacturing method according to the first aspect, since the intermediate film and the polycrystalline silicon film are formed by using each film forming material supplied from the outside, the silicon carbide (SiC This is done under the condition that both the set temperature of the carbon-based base material for forming the intermediate film and the set temperature of the carbon-based base material for forming the polycrystalline silicon film are both set just below the melting point of silicon. It becomes possible. Therefore, there is an advantage that the temperature of the carbon-based substrate can be easily controlled during the manufacturing process.

Here, in order to adjust the set temperature of the carbon-based substrate, the output of the high temperature plasma may be adjusted, or the heating means provided in the substrate holder may be adjusted. However, the method is arbitrary. Further, the set temperature of the carbon-based base material may be controlled by using the output adjustment of the high temperature plasma and the adjustment of the heating means provided in the base material holder together.

Next, when the carbon-based substrate 2 is placed in the reaction chamber 3, if the distance between the plasma-generating unit 1 and the carbon-based substrate 2 placed is too short, the plasma flame 15 from the plasma-generating unit 1 is increased. As a result, the carbon-based base material 2 may be overheated and damaged. On the contrary, if the distance is too large, it may be difficult to form the silicon film.

Therefore, it is desirable to select an appropriate distance corresponding to the conditions of the pressure inside the plasma generator 1, the shape of the plasma frame 15, the molten or decomposed state of the silicon raw material and the flow velocity of the molten or decomposed product.

When the carbon-based substrate 2 is fixedly arranged, the plasma frame 15 locally overheats the carbon-based substrate 2 to impair the uniformity of the silicon film formed. Therefore, a moving mechanism is provided in the substrate holder 7 that holds the carbon-based substrate 2, and the carbon-based substrate 2 is horizontally moved by this moving mechanism to prevent local overheating of the carbon-based substrate 2. Is desirable.

The application target of the silicon laminate obtained by the manufacturing method according to claim 1 is not limited to the above-mentioned solar cell, but may be an optical sensor or the like.

[0035]

According to the first aspect of the present invention, a mixture of a carbon-based base material set at a temperature just below the melting point of silicon and a gaseous silicon raw material, a carbon raw material, and an n-type or p-type dopant gas is mixed. After supplying a gas and reacting the mixed gas on the carbon-based substrate to form an intermediate film made of silicon carbide mixed with an n-type or p-type dopant, a silicon raw material containing silicon atoms is heated to a high temperature. This raw material is melted or decomposed by introducing it into plasma, and the melted or decomposed product is deposited on an intermediate film of a carbon-based base material set at a temperature just below the melting point of silicon to form a polycrystalline silicon film. There is.

In this manufacturing method, the mixed gas is supplied from the outside and the mixed gas is subjected to a gas phase reaction on the carbon-based substrate to form an intermediate film of silicon carbide (SiC). By properly controlling the mixing ratio of the mixed gas and the supply amount thereof, it becomes possible to reliably form an intermediate film which is a thin film in which an n-type or p-type dopant is mixed and whose film thickness and film quality are uniform.

Further, when the polycrystalline silicon film is formed on the intermediate film, the polycrystalline silicon film is formed under the condition that the temperature of the carbon-based substrate is just below the melting point of silicon. The difference between the temperature of the polycrystalline silicon film immediately after the film and the temperature of the carbon-based base material is reduced, and the film stress of the polycrystalline silicon film is reduced accordingly, and the silicon carbide having an intermediate property between carbon and silicon is obtained. The formed intermediate film also acts, and the synergistic effect of these can significantly reduce the film stress.

Further, when the polycrystalline silicon film is formed, the silicon raw material containing silicon atoms is introduced into the high temperature plasma to melt or decompose it. It is possible to apply high-grade silicon raw materials and metal-grade silicon particles containing impurities, and the melting or decomposition speed of the silicon raw materials is increased, and the supply speed of the melted or decomposed materials onto the interlayer film is also increased. Since the film forming speed can be improved and the whole process is performed under higher temperature conditions than in the past, it is possible to obtain a polycrystalline silicon film having a large crystal grain size.

Further, in this manufacturing method, the set temperature of the carbon-based base material when forming the intermediate film of silicon carbide and the set temperature of the carbon-based base material when forming the polycrystalline silicon film are both set. This is performed under the condition that the temperature is just below the melting point of silicon, and the temperature control of the carbon-based base material during the manufacturing process can be simplified accordingly.

[0040]

EXAMPLES Examples of the present invention will be described in detail below.

Example 1 First, as shown in FIG. 1, the silicon laminated body 20 according to this example has a sheet-like carbon fiber woven fabric 2 having no small holes throughout its entire area.
1, an intermediate film 22 made of silicon carbide formed over the entire surface of the carbon fiber woven fabric 21 and mixed with P (phosphorus) as an n-type dopant, and polycrystalline silicon film formed on the intermediate film 22. The membrane 23 and the main part thereof are constituted.

The carbon fiber woven fabric 21 has carbon fiber cloth (trade name: CFS) manufactured by Arisawa Manufacturing Co., Ltd. whose characteristics are shown in Table 1 below.
1140) has been applied.

[0043]

[Table 1] The silicon stack 20 is manufactured by the method described below. That is, as shown in FIG. 2, a high temperature plasma generating part 1 capable of forming arc plasma and induction plasma, and a reaction chamber 3 provided adjacent to the high temperature plasma generating part 1 and having a substrate holder 7 therein, The carbon fiber woven fabric 21 is arranged in the apparatus constituting the part, and the inside of the reaction chamber 3 is -10 ⁻³ Torr.
After evacuating the air and the like in the reaction chamber 3 until the plasma chamber is ignited, the carbon fiber woven cloth 21 is horizontally attached to the base material holder 7 prior to ignition in order to prevent rapid heating and local overheating after plasma ignition. A moving mechanism (not shown) for moving to (1) was operated.

Next, an argon gas and a hydrogen gas were introduced into the plasma generating section 1 and plasma ignition was performed. As the power source, direct current was first applied and then high frequency was applied.
The shape of the high temperature plasma flame varied considerably depending on the flow rates of argon gas and hydrogen gas, but a stable state could be obtained relatively easily. In addition, a pressure control valve is attached to a gas inlet of argon gas, hydrogen gas, etc. and an inlet of a silicon raw material, and an exhaust system 4 is provided downstream of the reaction chamber 3 in this apparatus. The mechanism keeps the pressure in the reaction chamber 3 at ˜550 Torr.

Then, the carbon fiber woven fabric 21
Is heated by high-temperature plasma and heating means 8 provided in the substrate holder 7 to monitor its surface temperature sufficiently using a radiation thermometer, and the surface temperature is directly below the melting point of silicon. When the temperature reaches 1400 ° C., a mixed gas of silane gas, methane gas, and phosphine gas (n-type dopant gas) is introduced from the gas introduction port, and this mixed gas is subjected to a gas phase reaction on the carbon fiber woven fabric 21. Thus, the intermediate film 22 made of silicon carbide mixed with the n-type dopant was formed.

(Conditions of Forming the Membrane) Pressure in the reaction chamber: 550 Torr DC plasma input power 5 KW RF plasma input power 30 KW Argon gas flow rate 60-80 liters / min Hydrogen gas flow rate 2-4 liters /
min Silane gas flow rate 0.5 liter /
min Methane gas flow rate 0.5 liter /
min Phosphine gas flow rate 0.1 liter /
min distance between high temperature plasma generating part and woven fabric 10 to 20 cm Next, the temperature of the carbon fiber woven fabric 21 is set to 140
While maintaining the temperature at 0 ° C., a fixed amount of silicon particles 6 are introduced from the inlet of the silicon raw material to melt the silicon particles 6 in high temperature plasma, and the melt is the intermediate film of the carbon fiber woven cloth 21. A film was formed on No. 22.

Then, this film forming treatment is performed for 2 to 3 minutes,
Further, even after the supply of the silicon particles 6 is stopped, a high frequency is applied to continue the high temperature plasma of argon to control the cooling for about 5 to 10 minutes to form a polycrystalline silicon film 23 with a film thickness of about 1 mm to form the above silicon laminated body. 20 was produced.

The moving mechanism provided on the base material holder 7 is continuously operated before the formation of the intermediate film 22 and during the cooling control of the silicon film.
The heat input to the surface is made uniform.

(Of a polycrystalline silicon film)
Film formation conditions) Pressure in reaction chamber ~ 550 Torr DC plasma input power 5KW RF plasma input power 30KW Argon gas flow rate 60-80 liters / min Hydrogen gas flow rate 2-4 liters /
min Particle size of silicon particles 75 to 150 μm Supply amount of silicon particles 1 g / min Distance between high temperature plasma generation part and woven fabric 10 to 20 cm TEM observation was conducted on the polycrystalline silicon film 23 thus obtained, and the film was found. It was confirmed that the crystal grain size reached about 100 μm at a thickness of about 1 mm, and that the film characteristics were also uniform.

[Example 2] The pressure in the reaction chamber was set to about 60 To.
rr and set DC plasma input power to 10K
A silicon laminated body was manufactured under substantially the same conditions as in Example 1 except that W and RF plasma input power were set to 50 KW.

Then, when the polycrystalline silicon film of this silicon laminated body was observed by TEM, it was confirmed that it had substantially the same characteristics as the polycrystalline silicon film of Example 1.

[0052]

According to the first aspect of the present invention, an intermediate film made of silicon carbide having a uniform film thickness and a uniform film quality, which is a thin film in which an n-type or p-type dopant is mixed on the surface of a carbon-based substrate, is surely obtained. A polycrystalline silicon film having a large crystal grain size and a small film stress can be formed on the intermediate film as well as being formed, and further, a silicon raw material or impurities having a high decomposition temperature, which is difficult to apply by the conventional method, can be formed. The metal grade silicon particles contained can be applied, and the film formation speed of the polycrystalline silicon film can be improved.

Therefore, there is an effect that a silicon laminated body which is directly applied to a BSF type solar cell or the like and which has a polycrystalline silicon film hardly peeling and which has excellent electric characteristics can be mass-produced easily and economically.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a silicon stack according to an example.

FIG. 2 is a structural conceptual diagram of an apparatus applied to the manufacturing method of the embodiment.

FIG. 3 is a schematic diagram of a high temperature plasma generation unit by a direct current method.

FIG. 4 is a schematic diagram of a high temperature plasma generation unit by a high frequency method.

FIG. 5 is a schematic cross-sectional view of a conventional solar cell.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 High temperature plasma generation part 2 Carbon type base material 3 Reaction chamber 7 Base material holder 8 Heating means 20 Silicon laminated body 21 Carbon fiber woven cloth 22 Intermediate film (SiC) 23 Polycrystalline silicon film

Claims (1)

[Claims] 1. A carbon-based substrate, an intermediate film made of silicon carbide formed on the surface of the carbon-based substrate and mixed with an n-type or p-type dopant, and a polycrystalline film formed on the intermediate film. In a method for manufacturing a silicon laminated body including a silicon film, a carbon-based base material set to a temperature just below a melting point of silicon is composed of a gaseous silicon raw material, a carbon raw material, and an n-type or p-type dopant gas. Gas mixture is supplied, and the mixed gas is reacted on the carbon-based substrate to form an intermediate film made of silicon carbide mixed with an n-type or p-type dopant, and then a silicon raw material containing silicon atoms. Is introduced into a high temperature plasma to melt or decompose the raw material, and the melted or decomposed product is deposited on an intermediate film of a carbon-based substrate whose temperature is set just below the melting point of silicon to form a polycrystalline silicon film. To do A method for manufacturing a silicon laminate, comprising: