JP2003054932A - Manufacturing device of semiconductor substrate, semiconductor substrate and manufacturing method thereof and solar cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor substrate having reduced warpage and reduced scratch or the like on the surface with a flat shape and a solar cell formed using the substrate. SOLUTION: The manufacturing method of the semiconductor substrate is provided with a part 1 housing a semiconductor molten liquid formed by melting a semiconductor material, a part 2 having a growing substrate 21 for growing the semiconductor substrate 4 and for dipping the surface part of the growing substrate 21 into the semiconductor molten liquid to grow the semiconductor substrate 4 on the surface and after that, pulling up the growing substrate 21 and a carrying part 3 which includes a substrate holding tool 31 having a substrate holding surface for holding the semiconductor substrate 4 and is for stripping the semiconductor substrate 4 from the growing substrate 21 by supplying air between the substrate holding surface and the semiconductor substrate 4 and for holding and carrying the semiconductor substrate 4. as it is. The semiconductor substrate 4 is manufactured using the manufacturing apparatus and the solar cell is manufactured using the semiconductor substrate 4.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a semiconductor substrate manufacturing apparatus, a semiconductor substrate and a manufacturing method thereof, and a solar cell.

[0002]

2. Description of the Related Art Conventionally, a polycrystalline silicon substrate used for a solar cell has been manufactured by the following method, which is a so-called casting method. A high-purity silicon material added with a dopant such as phosphorus or boron in an inert atmosphere is heated and melted in a crucible, and this melt is poured into a mold and cooled and solidified to obtain an ingot. By slicing the ingot, a thin plate-shaped polycrystalline silicon substrate can be obtained.

However, in such a method, a high-cost slicing process is required, and since the portion to be cut and removed in the slicing process is about the same as the thickness of the substrate, only half of the material can be used. There is a problem that this large material loss is an obstacle to cost reduction of the polycrystalline silicon substrate.

Therefore, as a method for directly obtaining a silicon substrate from a silicon melt in order to reduce the cost, Japanese Patent No. 25 has been proposed.
There is a silicon dendrite web crystal growth method disclosed in Japanese Patent No. 75838. By using this method, a thin silicon substrate can be obtained by pulling up dendrite web crystals while growing them in a silicon melt. However, the silicon dendrite web crystal growth method disclosed in Japanese Patent No. 2575838 has a production problem that the growth rate of the silicon substrate is low.

As a method for solving this productivity problem,
Japanese Unexamined Patent Publication No. 10-29895 discloses a silicon ribbon manufacturing apparatus and manufacturing method. A schematic sectional view of the manufacturing apparatus is shown in FIG.

As shown in FIG. 4, a cylindrical rotary cooling body 22 is immersed in a silicon melt 11 placed in an enclosure wall 121 in a crucible 12 to crystallize silicon on the surface thereof. A thin ribbon-shaped silicon substrate is obtained by peeling the silicon ribbon 40 from the surface of the rotary cooling body 22 using the wedge 35 and continuously pulling out the silicon ribbon 40 using the guide roller 9. The silicon melt 11 is stirred by the rotation of the propeller 81 in the stirring propeller component 8, and the pressure of the jet stream is used to pressurize and supply the silicon melt 11 to the outer peripheral surface of the rotary cooling body 22. Since these methods do not require a slicing step, the manufacturing cost of the silicon substrate can be reduced.

[0007]

However, JP-A-10-
In the silicon ribbon manufacturing apparatus and manufacturing method disclosed in Japanese Patent Publication No. 29895, since the silicon ribbon 40 is partially fixed to the surface of the rotary cooling body 22, the guide roller 9 is used.
It was necessary to peel off the fixed portion using the force for pulling out the outer silicon ribbon 40 of the manufacturing apparatus and the wedge 35.

The adhered portions are randomly scattered, and the silicon ribbon 40 shakes at the moment of peeling, causing the surface of the melt to become wavy, resulting in a problem that the surface irregularities of the silicon ribbon become large. In addition, when the area of the fixed portion is extremely large, there is a problem that a part of the silicon ribbon is chipped or broken during peeling, which hinders continuous withdrawal of the silicon ribbon.

In addition, the silicon ribbon 40 grown on the outer periphery of the cylindrical rotary cooling body 22 warps, and it is difficult to obtain a sufficiently flat silicon substrate in a large-area substrate. Further, since the guide roller 9 and the wedge 35 are always in contact with the surface of the silicon ribbon 40, there is a problem that the surface of the silicon substrate is scratched or soiled.

Further, the silicon ribbon manufactured by the method disclosed in Japanese Patent Laid-Open No. 10-29895 is compared with a polycrystalline silicon substrate manufactured by the casting method,
There is a problem that the conversion efficiency of the solar cell is poor.

That is, the ribbon-shaped silicon is grown in a flat shape on the surface of the cooling body and peeled from the cooling body without damage, and the quality of the ribbon-shaped silicon as a solar cell substrate is inferior to the casting method. It has become a challenge.

[0012] Therefore, an object of the present invention is to provide a semiconductor substrate having a flat shape, little warpage, and almost no scratches or stains on the surface, and a solar cell having excellent characteristics using the substrate. .

[0013]

A semiconductor substrate manufacturing apparatus according to the present invention is a semiconductor melt containing component for containing a semiconductor melt in a semiconductor material melt state, and a growth substrate for growing a semiconductor substrate. A semiconductor substrate growth component that has a flat portion of the growth substrate, which is immersed in a semiconductor melt to grow the semiconductor substrate on the flat portion, and then pulls up the growth substrate; and a substrate holding surface for holding the semiconductor substrate. A carrier for separating the semiconductor substrate from the growth substrate by supplying gas between the substrate holding surface and the semiconductor substrate, holding the semiconductor substrate, and transporting the semiconductor substrate in this state. And means.

By growing the semiconductor substrate on the plane portion of the growth substrate as described above, it is possible to grow a semiconductor substrate having a flat shape with less warpage. Further, by supplying gas between the substrate holding surface and the semiconductor substrate in the substrate holder of the present invention, the semiconductor substrate can be cooled, and the difference in the coefficient of thermal expansion between the semiconductor substrate and the growth substrate can be used. The semiconductor substrate can be separated from the growth substrate.
Thereby, it is possible to prevent the surface of the semiconductor substrate from being scratched or soiled during the peeling. Then, by further supplying a gas between the substrate holding surface and the semiconductor substrate, a negative pressure can be generated between them. This allows the semiconductor substrate to exert an attractive force on the substrate holding surface, and the semiconductor substrate can be held by the substrate holder. In this state, the semiconductor substrate can be transferred to the substrate transfer chamber. By using a gas containing hydrogen gas (for example, hydrogen gas or a mixed gas of hydrogen gas and an inert gas), the effect of improving the quality of the semiconductor substrate can be expected.

The semiconductor substrate growth component is preferably
It includes a rotating body having a plurality of growth substrates and rotating to rotate so that the plane portions of the growth substrates are sequentially immersed in the semiconductor melt to grow the semiconductor substrates. Further, the carrying means preferably includes a moving means for moving the substrate holder so that the semiconductor substrate grown on the growth substrate and the substrate holding surface face each other.

Since the semiconductor substrate growth component includes the rotating body as described above, the rotating body can be rotated to continuously grow the semiconductor substrates on the plurality of growth substrates. Further, since the transporting means includes the above moving means, the substrate holder can be moved so that the upper surface of the semiconductor substrate grown on the growth substrate and the substrate holding surface are opposed to each other. By supplying gas between the substrate holding surface and the semiconductor substrate in this state, the semiconductor substrate can be separated from the growth substrate and the semiconductor substrate can be held by the substrate holder as described above.

The semiconductor substrate is preferably a polycrystalline silicon substrate. In general, single crystal silicon is easily cleaved because its crystallographic orientation is uniform, but a polycrystalline silicon substrate has high mechanical strength because its crystallographic orientation is not uniform. Therefore, it is possible to prevent damage to the semiconductor substrate when the semiconductor substrate is transferred by the transfer method according to the present invention.

The semiconductor substrate according to the present invention is manufactured by using the above-described semiconductor substrate manufacturing apparatus. Since the semiconductor substrate is grown on the plane portion of the growth substrate in the manufacturing apparatus, a flat semiconductor substrate with less warp can be obtained, and since members such as wedges are not used at the time of peeling the semiconductor substrate, peeling can be performed. Sometimes, it is possible to avoid scratches and stains on the semiconductor substrate.

The solar cell according to the present invention has excellent characteristics because it is manufactured by using the flat semiconductor substrate with less warpage as described above.

The method of manufacturing a semiconductor substrate according to the present invention comprises a step of immersing a flat portion of a growth substrate for growing the semiconductor substrate in a semiconductor melt to grow the semiconductor substrate on the flat portion, and the semiconductor substrate together with the growth substrate. Is pulled out of the semiconductor melt and moved to a predetermined position, and a substrate holder having a substrate holding surface is moved so that the substrate holding surface is located on the semiconductor substrate, and then gas is blown onto the surface of the semiconductor substrate. And a step of peeling the semiconductor substrate from the growth substrate, holding the semiconductor substrate by the substrate holder, and transporting the semiconductor substrate in this state.

By growing the semiconductor substrate on the flat surface portion as described above, it is possible to grow the semiconductor substrate in a flat shape with less warpage. This semiconductor substrate is pulled up from the semiconductor melt, and gas is blown onto the surface of the semiconductor substrate to peel off the semiconductor substrate from the growth substrate, so that it is possible to prevent the semiconductor substrate from being scratched or soiled during peeling. In addition, since the semiconductor substrate is held by the substrate holder by using the negative pressure generated by blowing the gas onto the surface of the semiconductor substrate, the semiconductor substrate can be held in a non-contact state, and can be transported in this state. You can Accordingly, it is possible to avoid scratches or stains on the semiconductor substrate during transportation.

The gas blown onto the surface of the semiconductor substrate is preferably hydrogen gas or a mixed gas of hydrogen gas and an inert gas.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to FIGS.

FIG. 1 is a schematic cross-sectional view of a semiconductor substrate manufacturing apparatus according to one embodiment of the present invention. The semiconductor substrate manufacturing apparatus according to the present invention includes a substrate manufacturing chamber 5, a substrate unloading chamber 6, and a gate valve 7. In a substrate manufacturing chamber 5, a component 1 for accommodating a semiconductor material in a molten state, a component 2 for growing a semiconductor substrate, and a conveying component 3 for a semiconductor substrate are installed. Details of each component will be described below.

First, the component 1 for containing the semiconductor material in a molten state will be described. This component 1 is a semiconductor melt 11
Crucible 12 for heating, heating means 13 for semiconductor melt 11,
The elevator 14 has a temperature monitor for the semiconductor melt 11 (not shown).

The material of the crucible 12 has no heat to the semiconductor material and has heat resistance, and is made of, for example, high density graphite. The heating means 13 for the melt 11 is, for example, a heater or an induction heating coil, and these may be used together. The temperature monitor of the melt 11 is, for example, a thermocouple or a radiation thermometer, and these may be used together. The crucible 12 is mounted on a lift 14 so that the height of the semiconductor melt surface can be finely adjusted. Further, the melt surface is monitored by a camera (not shown).

Next, a description will be given of the component 2 for growing the semiconductor substrate on the surface of the growth substrate by successively immersing the growth substrate in the melt and then pulling it up. The component 2 has a growth substrate 21 having a substantially flat main surface for growing the semiconductor substrate 4, and a rotary cooling for dipping the semiconductor substrate 11 in the semiconductor melt 11 and pulling it from the melt 11 while cooling the growth substrate 21. It has a body 22. A plurality of growth substrates 21 are attached to the outer periphery of the rotary cooling body 22 at equal intervals, and the growth substrate 21 is cooled by heat exchange with the rotary cooling body 22. The material of the growth substrate 21 is, for example, high density graphite. The main surface on which the semiconductor substrate 4 is grown may remain as high-density graphite,
A coating such as carbon nitride, silicon nitride or boron nitride may be applied. The rotary cooling body 22 can be rotated by an arbitrary angle or stopped at an arbitrary position. Helium gas, nitrogen gas, air, a mixed gas of these, water, or the like can be used as the refrigerant flowing inside the rotary cooling body 22, and the flow rate and supply pressure of the refrigerant are controlled.

Next, the semiconductor substrate carrying component 3 will be described. The carrying part 3 includes a substrate holder 31, a stopper 32, a gas supply pipe 33, and a moving part 34 of the substrate holder 31.
Have. The substrate holder 31 is shown in FIG.

The substrate holding surface 311 of the substrate holder 31 facing the semiconductor substrate 4 is a flat surface having substantially the same size and shape as the semiconductor substrate 4, and a gas supply port 312 is provided at the center of the substrate holding surface 311. is open. The substrate holder 31 is a so-called Bernoulli chuck, and the principle thereof is that the substrate holding surface of the carrier component is arranged so as to face the upper surface of the thin substrate to be transported, and the semiconductor substrate 4 is supplied from the gas supply port of the substrate holding surface. The gas blown toward the upper surface of the substrate is laminarly flowed to form a negative pressure layer, and the negative pressure layer causes the semiconductor substrate 4 to move to the substrate holding surface 3
11 is floated in a non-contact state.

Specifically, by ejecting the gas from the gas supply port 312 toward the semiconductor substrate 4, a negative pressure is generated between the semiconductor substrate 4 and the substrate holding surface 311 and the semiconductor substrate 4 has a substrate. An attractive force acts on the holding surface 311. At the same time, a repulsive force is generated by the gas ejection. The semiconductor substrate 4 is held in a non-contact manner at a position where these forces and gravity of the semiconductor substrate 4 balance each other.

As is well known, the Bernoulli chuck has a function of correcting a minute positional deviation in the horizontal direction so that the force applied to the substrate to be held is not asymmetric in the plane. The semiconductor substrate 4 and the stopper 32 do not come into contact with each other if this positional deviation is minute, but the substrate holder 31 is provided with a stopper 32 in the periphery thereof for correction when the positional deviation is too large.

2A and 2B, the gas supply port 31 is shown.
2 shows only one substrate holder 31 in the center, but the scope of the present invention is not limited to this. For example, as shown in FIGS. A substrate holder 31 having a plurality of gas supply ports 312 arranged symmetrically with respect to the center may be used.

The gas supply pipe 33 is flexible and is arranged so as not to hinder the movement of the substrate holder 31.
The gas whose pressure and flow rate are controlled from the outside is the gas supply pipe 33.
Through to the gas supply port 312. Hydrogen gas or a mixed gas of a rare gas and hydrogen gas is used as the gas. The reason why hydrogen gas is used here is to subject the high-temperature semiconductor substrate 4 to hydrogen treatment immediately after fabrication.

Although energetic research has been continued, there are still many unclear points about the detailed mechanism of hydrogen treatment, and its effect varies depending on process conditions. There are many known examples of improving It is desirable to use high-purity gas for the semiconductor industry. Furthermore, it is desirable to remove particles and impurities such as oxygen and water in the gas by using a filter or a purifying device.

The moving part 34 of the substrate holder 31 is composed of, for example, an arm, a column, a motor and the like. In this case, the substrate holder 31 is horizontally moved by the rotation of the arm around the column, and the substrate holder 31 is vertically moved by vertically moving the column itself. The semiconductor substrate 4 can be carried from the growth substrate 21 to the substrate unloading chamber 6 by interlocking the rotation of the rotary cooling body 22, the gas supply to the substrate holder 31, and the horizontal and vertical movement of the moving component 34 with each other.

The above-mentioned components are arranged in a substrate manufacturing chamber 5 which can be hermetically sealed. By using a gas supply means (not shown) and an exhaust pump, the inside of the substrate forming chamber 5 can be evacuated, or an inert gas such as helium or argon can be constantly flown into the substrate forming chamber 5. The substrate manufacturing chamber 5 is adjacent to the substrate unloading chamber 6 via the gate valve 7.

The semiconductor substrate transfer component 3 can move horizontally between the substrate manufacturing chamber 5 and the substrate unloading chamber 6. There is a substrate unloading component (not shown) in the substrate unloading chamber 6, and the semiconductor substrate 4 is transferred from the carrying component 3 to the substrate unloading component. The gate valve 7 is opened when the semiconductor substrate 4 is moved from the substrate preparation chamber 5 to the substrate unloading chamber 6, and the gate valve 7 is closed when the semiconductor substrate 4 is taken out of the device from the substrate unloading chamber 6. Moreover, the substrate manufacturing chamber 5 has a semiconductor material supply component (not shown), and the semiconductor material can be supplied to the crucible 12 without bringing outside air into the substrate manufacturing chamber 5.

As another embodiment, the internal pressure of the substrate manufacturing chamber 5 may be kept slightly higher than the atmospheric pressure so that external air does not enter the substrate manufacturing chamber 5. In this case, the semiconductor substrate can be continuously transported with the gate valve 7 kept open.

Next, a method of manufacturing a semiconductor substrate using the manufacturing apparatus of the present invention will be described. First, the rotary cooling body 22
The growth substrate 21 is attached to. Next, a predetermined amount of semiconductor material is put into the crucible 12. Depending on the purpose, a doping material may be mixed with the semiconductor material.

Next, an inert gas such as helium or argon is introduced to replace the air in the substrate manufacturing chamber 5. The semiconductor material in the crucible 12 is melted using the heating means 13 while flowing an inert gas into the substrate manufacturing chamber 5.
From the viewpoint of safety, the flow rate of the inert gas introduced into the substrate preparation chamber 5 is 30 times or more the flow rate of hydrogen gas in the gas used for the Bernoulli chuck described later, and the atmosphere in the substrate preparation chamber 5 is set to the lower explosion limit. It is desirable to be less than. At the same time, the refrigerant is made to flow inside the rotary cooling body 22. When the semiconductor material in the crucible 12 is melted, the semiconductor melt 1
Finely adjust the height of the liquid surface of 1.

Next, the growth substrate 21 is immersed in the semiconductor melt 11 in the crucible by rotating the rotary cooling body 22 by a predetermined angle, and the semiconductor substrate 4 is placed on the main surface of the growth substrate 21.
To solidify and grow. The plate thickness of the semiconductor substrate 4 can be controlled by the temperature of the semiconductor melt 11, the flow rate of the coolant in the rotary cooling body 22, the height of the liquid surface of the semiconductor melt 11, the immersion time, and the like. By further rotation of the rotary cooling body 22, the growth substrate 2
1 and the semiconductor substrate 4 grown on the main surface thereof are pulled up from the semiconductor melt 11.

Next, by further rotating the rotary cooling body 22, the growth substrate 21 and the semiconductor substrate 4 attached to the main surface thereof are moved to a position where they are substantially horizontal, and the rotary cooling body 22 is moved.
Stop rotating. Next, the substrate holder 31 is moved,
The substrate holding surface 311 of the transport component 3 is brought close to directly above the semiconductor substrate 4. At this point, both the semiconductor substrate 4 and the growth substrate 21 in contact with the semiconductor substrate 4 are at a high temperature.

Next, the substrate holder 31 is attached to the surface of the semiconductor substrate 4.
Gas is sprayed from the gas supply port 312 of the semiconductor substrate 4
To cool. There is a difference in the coefficient of thermal expansion between the semiconductor substrate 4 and the growth substrate 21. For example, at 400 ° C., the coefficient of thermal expansion when the semiconductor substrate is silicon is 4.0 × 10 ⁻⁶ /
K, the growth substrate is high-density graphite (Toyo Tanso IG-
430), the coefficient of thermal expansion is 4.8 × 10 ⁻⁶ / K.

As the semiconductor substrate 4 is cooled, stress due to thermal contraction is applied. At the same time, the Bernoulli effect exerts an attractive force on the semiconductor substrate 4 toward the substrate holding surface 311. As a result, the semiconductor substrate 4 is separated from the growth substrate 21 and held by the substrate holder 31 in a non-contact manner.

Next, the substrate holder 31 is moved to the substrate unloading chamber 6 by using the component 34 for moving the substrate holder 31 in the horizontal and vertical directions while keeping the semiconductor substrate 4 held by continuously ejecting the gas. . During transportation, the semiconductor substrate 4 only contacts the end portion of the semiconductor substrate 4, and the main surface of the semiconductor substrate 4 does not contact the substrate holding surface 311. If the supply of gas is stopped, the attractive force due to the Bernoulli effect disappears, and the semiconductor substrate 4 is left standing in the substrate unloading chamber 6.

On the other hand, the growth substrate 21 which has been peeled off the semiconductor substrate 4 and left on the rotary cooling body 22 is used again for manufacturing the semiconductor substrate 4 without being exposed to the outside air. Since the amount of the semiconductor melt 11 in the crucible 12 decreases as the semiconductor substrate 4 is continuously manufactured, the height of the liquid surface of the semiconductor melt 11 is finely adjusted using the elevating table 14 or the semiconductor material is crucible. Add to 12. By repeating the above process, a plurality of semiconductor substrates can be continuously manufactured.

Next, a method of manufacturing a solar cell using a semiconductor substrate manufactured by using the semiconductor substrate manufacturing apparatus of the present invention will be described.

(1) Texture processing: Processing is performed so that one surface of the semiconductor substrate, which is the light receiving surface of the solar cell, has an uneven shape. Specifically, for example, a reactive ion etching process, an acid etching process, a groove process with a dicing blade, a sandblast process, or the like is performed.

(2) RCA cleaning: Organic substances on the surface of the semiconductor substrate are removed by using a mixed aqueous solution of hydrogen peroxide and ammonia. Next, the oxide film on the surface is removed by etching with a hydrofluoric acid aqueous solution. Then, the metal impurities on the lower surface are removed using a mixed aqueous solution of hydrogen peroxide and hydrochloric acid. Next, the oxide film on the surface is removed by etching with a hydrofluoric acid aqueous solution.

(3) N ⁺ Diffusion: A semiconductor substrate is put in a quartz tube of a diffusion furnace, and a POCl ₃ mixed gas is caused to flow at a predetermined temperature while heating with a heater around the tube so that phosphorus is deposited on the surface of the semiconductor substrate. Spread. Next, the phosphorus silicon glass film on the surface is removed by etching with a hydrofluoric acid aqueous solution.

(4) Oxidation passivation: A semiconductor substrate is placed in a quartz tube of an oxidation furnace, and a gas containing oxygen is flowed for a predetermined time while heating with a heater around the tube to form an oxide film on the surface of the semiconductor substrate. To do.

(5) Antireflection film formation: CVD is performed on the light-receiving surface of the semiconductor substrate having the unevenness formed by the above texture processing.
An antireflection film of titanium oxide, silicon nitride or the like is formed by using the (Chemical Vapor Deposition) method.

(6) Backside etching: A resist is applied to the surface of the antireflection film. Next, the oxide film and the phosphorus diffusion layer on the back surface and the peripheral portion of the semiconductor substrate are etched using hydrofluoric nitric acid. Next, the resist is peeled off.

(7) Back surface electrolytic layer formation: Aluminum paste is applied to the back surface of the semiconductor substrate. Next, a back surface electric field layer is formed using a firing furnace.

(8) Formation of light-receiving surface electrode: A silver paste is applied to the light-receiving surface of the semiconductor substrate in a fishbone pattern or the like by using a screen printing method or the like. Next, using a firing furnace, the antireflection film is penetrated to bring the silver electrode into contact with the phosphorus diffusion layer of the semiconductor substrate to form a light-receiving surface electrode.

(9) Lead frame bonding: The lead frame is soldered to the surface of the main grid of the light receiving electrode of the semiconductor substrate.

[0057]

EXAMPLES Next, in order to compare the semiconductor substrate manufacturing apparatus, the semiconductor substrate manufacturing method, and the solar cell according to the present invention with the prior art, semiconductor substrates were manufactured under various manufacturing conditions. The details of the study will be described below.

(Example 1) The growth substrate 2 made of high-density graphite (ash content: 10 ppm or less) on the rotary cooling body 22.
I installed 1. The main surface of the growth substrate 21 is 150 mm □,
What was polished by using # 1000 silicon carbide abrasive grains was used. As shown in FIG. 1, the number of growth substrates 21 installed is three, and the number of growth substrates 21 is 12 on the outer circumference of the side surface of the rotary cooling body 22.
It was attached at equal intervals to form an angle of 0 °. The rotary cooling body 22 is cylindrical and has a diameter of 550 mm and a width of 200 mm. The normal line passing through the center of the main surface of the growth substrate 21 attached to the rotary cooling body 22 is in a positional relationship such that it is orthogonal to the rotation axis of the rotary cooling body 22.

Next, high-density graphite (ash content: 10 p
crucible 12 made of pm or less), and a high-purity polycrystalline silicon raw material (purity = 99.9999999999%) 1
00 kg and silicon pellets containing boron (concentration: 0.
02 atom%) and 200 g.

Next, the substrate preparation chamber 5 and the substrate unloading chamber 6 were sealed with the gate valve 7 opened, and the inside was evacuated to 1 Torr (133 Pa) using a vacuum pump. Next, an argon gas from which water and oxygen were removed to 1 ppb or less was supplied to the substrate manufacturing chamber 5 through a getter-type purifying device, and the argon gas was filled until the inside of the chamber became atmospheric pressure. Thereafter, in the same manner, evacuation and filling with argon gas were repeated three times to purge the air in the room.

Next, while flowing argon gas at a flow rate of 600 SLM, a vacuum pump and a pressure regulating valve are used together to keep the inside of the substrate manufacturing chamber 5 at atmospheric pressure, and a heater as a heating means 13 is used to form a crucible 12 in the crucible 12. The silicon raw material put in was heated and heated. The temperature was monitored using a thermocouple in contact with the crucible 12, and the heater power was controlled so that the temperature rising rate was 10 ° C./min. At the same time, nitrogen gas was made to flow inside the rotary cooling body 22 as a refrigerant at a flow rate of 1000 SLM. In this way, the silicon raw material is melted and the temperature of the silicon melt 11 becomes 14
It was kept at 50 ° C.

Next, when the growth substrate 21 attached to the rotary cooling body 22 is immersed deepest in the silicon melt 11,
Using a camera that monitors the liquid surface of the silicon solution 11 through the viewing window of the substrate preparation chamber 5 and the lift table 14 so that the main surface of the growth substrate 21 is located 3 mm below the liquid surface,
The height of the liquid surface of the silicon melt 11 was adjusted by moving the crucible 12 up and down.

Next, the rotary cooling body 22 was rotated by 60 ° and the main surface of the growth substrate 21 was immersed in the silicon melt 11. After the growth of the silicon substrate 4 by immersion for 2 seconds, the rotary cooling body 22 was further rotated by 60 ° in the same direction to pull up the growth substrate 21 from the silicon melt 11.

In this way, the rotary cooling body 22 was repeatedly rotated by 60 °, and the initially grown silicon substrate 4 was moved to a position facing the ceiling surface of the substrate manufacturing chamber 5. Next, using the moving part 34 of the substrate holder 31, the substrate holder 31
Was brought close to a position 1 mm away from the main surface of the silicon substrate 4. The substrate holder 31 is made of synthetic quartz. As shown in FIG. 2, the substrate holding surface 311 is the same as the growth substrate 21.
Gas supply port 3 with a diameter of 50 mm and a diameter of 1 mm in the center
There are twelve. Further, the substrate holder 312 is provided with four stoppers 32 made of synthetic quartz. Stopper 32
Is at a position 1 mm away from the end surface of the substrate holding surface 311 and extends to a position 2 mm below the substrate holding surface 311.

Subsequently, hydrogen gas (purity = 99.99999% or more) was caused to flow from the gas supply port 312 through the gas supply pipe 33 at a flow rate of 20 SLM. Hydrogen gas flows at a high speed between the substrate holding surface 311 and the main surface of the silicon substrate 4,
The silicon substrate 4 was peeled off from the main surface of the growth substrate 21 and held by the substrate holder 31 in a non-contact manner. The size of the silicon substrate 4 is 150 mm □.

Next, the substrate holder 3 with hydrogen gas kept flowing.
The moving part 34 of No. 1 was operated to move the silicon substrate 4 vertically upward. Subsequently, the silicon substrate 4 was moved to the substrate unloading chamber 6 in the same manner. Then, the supply of hydrogen gas was stopped, and the silicon substrate 4 was allowed to stand in the substrate unloading chamber 6.

In parallel with the above steps, a semiconductor material supply component (not shown) is used between the pulling of the growth substrate 21 from the silicon melt 11 and the immersion of the next growth substrate 21 in the silicon melt 11. Then, 13.1 g of silicon raw material having the same boron concentration as that of the silicon melt 11 was melted and additionally supplied to the crucible 12.

In this way, the silicon substrate is continuously
As a result of producing 000 sheets, the yield related to scratches and chips of the silicon substrate was 98%. The average thickness of good products is 2
It was 50 μm. Also, all manufactured silicon substrates were not warped.

The surface roughness of 100 silicon substrates was measured using a contact type surface roughness meter. The measurement was performed along the diagonal line of the substrate within a range of ± 100 mm from the center. When the surface that was in contact with the carbon substrate was the release surface and the surface on the opposite side was the melt surface, the average value of the maximum height Rmax was 32 μm for the melt surface and 21 μm for the release surface.

A solar cell was manufactured using the silicon substrate manufactured as described above. The process procedure is as described above. A solar cell was manufactured by selecting 100 pieces from non-defective products having no scratches or chips on the silicon substrate, and the average conversion efficiency was 15.0%.

Comparative Example 1 For comparison with the prior art,
A silicon substrate was manufactured using the silicon ribbon manufacturing apparatus shown in FIG. Note that, as in Example 1, the manufacturing apparatus in FIG. 4 is in the substrate manufacturing chamber.

As the material of the rotary cooling body 22, high density graphite (ash content: 10 ppm or less) was used. Diameter 500m
A cylindrical shape having a width of m and a width of 150 mm and having an outer peripheral surface polished with # 1000 silicon carbide abrasive grains was used. A carbon net having a width of 150 mm was wound around the outer periphery of the rotary cooling body 22, and the carbon net was passed through the guide roller 9. High-density graphite (ash content: 10 ppm or less) was also used as the material of the guide roller 9.

Next, as shown in FIG. 4, a wedge 35 made of high-density graphite (ash content: 10 ppm or less) whose tip was coated with silicon carbide was installed so as to contact the rotary cooling body 22 and the carbon net. . The peeling between the rotary cooling body 22 and the silicon ribbon 40 is mainly performed by the force of the guide roller 9 pulling up the silicon ribbon 40, and the wedge 35 is merely provided to assist the peeling.

Next, high-density graphite (ash content: 10 p
100 kg of high-purity polycrystalline silicon raw material (purity: 99.99999999999% or more) in a crucible 12 made of pm or less) and an enclosure wall 121 made of the same material.
And 200 g of silicon pellets containing boron (concentration 0.02 atomic%).

Next, argon gas was introduced into the substrate manufacturing chamber to 20 times.
Flowed at a flow rate of 0 SLM. The inside of the substrate preparation chamber was purged by extruding argon gas together with air from the outlet of the silicon ribbon opened on the side wall of the substrate preparation chamber. Next, using a heater (not shown), the crucible 12
The silicon raw material placed in the enclosure wall 121 was heated and heated. The temperature was monitored using a thermocouple in contact with the crucible 12, and the heater power was controlled so that the temperature rising rate was 10 ° C./min. At the same time, nitrogen gas as a refrigerant was caused to flow inside the rotary cooling body 22 at a flow rate of 1000 SLM. In this way, the silicon raw material is melted and the temperature of the silicon melt 11 becomes 1450.
It was kept at ℃.

Next, the propeller 81 of the stirring propeller part 8 made of high-density graphite (ash content: 10 ppm or less) whose surface is coated with silicon carbide is rotated at a rotation speed of 100 rpm, and the upper portion of the wall 121 surrounding the silicon melt 11 is rotated. Of the crucible 12 and the surrounding wall 121 were circulated in the crucible 12 at all times.

Next, a camera that monitors the liquid surface of the silicon melt 11 through the viewing window of the substrate manufacturing chamber so that the lowermost part of the rotary cooling body 22 is located 3 mm below the liquid surface of the silicon melt 11. The height of the liquid surface of the silicon melt 11 was adjusted by raising and lowering the crucible 12 and the surrounding wall 121 by using an elevator (not shown). When the rotary cooling body 22 was immersed in the silicon melt 11, silicon began to grow on the carbon net wound around the rotary cooling body 22.

Subsequently, the rotary cooling body 22 was rotated at an angular velocity of 6 rpm, and the rotation of the guide roller 9 was synchronized with this, and the carbon net was pulled out. The silicon ribbon is crystal-grown at the portion of the outer periphery of the rotary cooling body 22 which is immersed in the silicon melt 11, and is peeled from the surface of the rotary cooling body 22 by the wedge 35. I pulled it out. At the same time, a silicon raw material having the same boron concentration as the silicon melt 11 was melted and continuously supplied to the crucible 12 at a rate of 16.5 g / sec.

Next, the silicon ribbon pulled out of the manufacturing apparatus was cut with a band saw to produce a substrate of 150 mm □.

As a result of continuously producing 1000 silicon substrates in this way, the yield related to scratches and chips of the silicon substrate was 76%. The average plate thickness of the non-defective product was 300 μm. In addition, the manufactured silicon substrate is warped so that the peeling surface becomes concave along the drawing direction,
There was a warp of 0.8 mm on average for 100 good products.

The surface roughness of 100 silicon substrates was measured using a contact type surface roughness meter. We also used a sample stand that was able to attract and flatten the warped substrate. The measurement was performed along the diagonal line of the substrate within a range of ± 100 mm from the center. Assuming that the surface in contact with the carbon substrate was the release surface and the surface on the opposite side was the melt surface, the average value of the maximum height Rmax was 72 μm for the melt surface and 81 μm for the release surface.

A solar cell was manufactured using the silicon substrate manufactured as described above. The process procedure is as described above. When 100 solar cells were prepared from non-defective silicon substrates having no scratches or chips, the average conversion efficiency was 13.2%.

(Comparative Example 2) A silicon substrate was manufactured in the same manner as in Example 1 by using a carrying component using a vacuum chuck instead of a Bernoulli chuck as a substrate holder. The substrate holding surface of the vacuum chuck is the same as that of the first embodiment.
Although it is 0 mm □, there is no stopper around the substrate holder,
The substrate holding surface used was one in which vacuum suction holes were evenly opened at equal intervals. The substrate holding surface was made of synthetic quartz.

The procedure for peeling the silicon substrate from the growth substrate is as follows. First, the moving part of the substrate holder was used to bring the substrate holding surface close to the main surface of the silicon substrate and bring them into close contact. Next, the silicon substrate was vacuum-adsorbed on the substrate holding surface. Subsequently, the substrate holder was vertically moved to separate the silicon substrate from the growth substrate.

In this way, the silicon substrate is continuously
As a result of producing 000 sheets, the yield related to scratches and chips of the silicon substrate was 84%. Also, all manufactured silicon substrates were not warped.

In the same manner as in Example 1, the surface roughness of 100 non-defective silicon substrates without scratches or chips was measured. The average value of the maximum height Rmax was 51 μm on the melt surface and 24 μm on the peeling surface.

A solar cell was manufactured using the silicon substrate manufactured as described above. The process procedure is as described above. When 100 solar cells were produced from good products having no scratches or chips on the silicon substrate, the average conversion efficiency was 13.6%.

(Comparative Example 3) Argon gas (purity: 99.999) was used instead of hydrogen gas as a gas for holding the substrate.
9% or more) was used to manufacture a silicon substrate in the same manner as in Example 1.

As a result of continuously producing 1000 silicon substrates, the yield related to scratches and chips of the silicon substrates was 98%. Also, all manufactured silicon substrates were not warped.

In the same manner as in Example 1, the surface roughness of 100 non-defective silicon substrates without scratches or chips was measured. The average value of the maximum height Rmax was 31 μm on the melt surface and 22 μm on the peeled surface.

A solar cell was manufactured using the silicon substrate manufactured as described above. The process procedure is as described above. A solar cell was manufactured by selecting 100 non-defective silicon substrates without scratches or chips, and the average conversion efficiency was 13.9%. (Comparative Example 4) For comparison with the conventional technique, a solar cell was produced in the same manner as in Example 1 using a polycrystalline silicon substrate produced by a casting method. The size of the silicon substrate is 150 mm □ and the thickness is 25.
It sliced so that it might become 0 micrometer. When 100 solar cells were produced, the average conversion efficiency was 15.2%.

Although the embodiments of the present invention have been described above, it should be considered that the embodiments disclosed this time are exemplifications in all points and not restrictive. The scope of the present invention is defined by the claims, and includes meanings equivalent to the claims and all modifications within the scope.

[0093]

According to the semiconductor substrate manufacturing apparatus and manufacturing method of the present invention, it is possible to manufacture a semiconductor substrate having a flat shape with little warpage and without scratches or dirt on the surface. As a result, a semiconductor substrate having excellent characteristics can be manufactured with high yield and low cost.

Since the semiconductor substrate of the present invention is manufactured by the above-described semiconductor substrate manufacturing apparatus and manufacturing method, the semiconductor substrate has a flat shape with little warpage and almost no scratches or stains on the surface. Further, since the solar cell according to the present invention is manufactured using the semiconductor substrate having excellent characteristics as described above,
It has excellent characteristics at low cost.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a semiconductor substrate manufacturing apparatus according to an embodiment of the present invention.

FIG. 2A is a schematic cross-sectional view showing an example of a substrate holder and a stopper according to the present invention and a positional relationship between the substrate holder and a semiconductor substrate. FIG. 2B is a plan view showing the substrate holder and the stopper shown in FIG.

FIG. 3A is a schematic cross-sectional view showing another example of the substrate holder according to the present invention and the positional relationship between the substrate holder and the semiconductor substrate. FIG. 3B is a plan view showing the substrate holder and the stopper shown in FIG.

FIG. 4 is a schematic cross-sectional view of a conventional semiconductor substrate manufacturing apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Components for containing a semiconductor material in a molten state, 11 Semiconductor melts, 12 crucibles, 121 Enclosing walls, 13 Heating means, 14 Elevating tables, 2 Components for growing semiconductor substrates,
21 growth substrate, 22 rotary cooling body, 3 semiconductor substrate carrying parts, 31 substrate holder, 311 substrate holding surface, 31
2 gas supply holes, 32 stoppers, 33 gas supply pipes,
34 substrate holder moving parts, 35 wedges, 4 semiconductor substrates, 5 substrate preparation chambers, 6 substrate unloading chambers, 7 gate valves, 8 stirring propeller parts, 81 propellers, 40 silicon ribbons, 9 guide rollers.

Claims (8)

[Claims] 1. A semiconductor melt containing component for containing a semiconductor melt in which a semiconductor material is in a melted state, and a growth substrate for growing a semiconductor substrate, wherein the plane portion of the growth substrate is the semiconductor melt. A substrate holding surface having a substrate holding surface for holding the semiconductor substrate, and a semiconductor substrate growing component for pulling up the growth substrate after the semiconductor substrate is grown on the flat surface by immersing the substrate in the flat surface portion; And holding the semiconductor substrate while peeling the semiconductor substrate from the growth substrate by supplying a gas between the semiconductor substrate,
An apparatus for manufacturing a semiconductor substrate, comprising: a transfer unit that transfers the semiconductor substrate in this state. 2. The semiconductor substrate growth component comprises a plurality of the growth substrates, and a rotating body for growing the semiconductor substrates by rotating so that the flat surface portion of the growth substrate is sequentially immersed in the semiconductor melt. The manufacturing of a semiconductor substrate according to claim 1, further comprising: a moving unit that moves the substrate holder so that the semiconductor substrate grown on the growth substrate faces the substrate holding surface. apparatus. 3. The semiconductor substrate manufacturing apparatus according to claim 1, wherein the semiconductor substrate is a polycrystalline silicon substrate. 4. The semiconductor substrate manufacturing apparatus according to claim 1, wherein the gas blown onto the surface of the semiconductor substrate is hydrogen gas or a mixed gas of hydrogen gas and an inert gas. 5. A semiconductor substrate manufactured by using the semiconductor substrate manufacturing apparatus according to claim 1. 6. A solar cell manufactured using the semiconductor substrate according to claim 5. 7. A step of immersing a flat surface portion of a growth substrate for growing a semiconductor substrate in a semiconductor melt to grow the semiconductor substrate on the flat surface portion, and the growth substrate and the semiconductor substrate together with the semiconductor melt. And moving the substrate holder having the substrate holding surface so that the substrate holding surface is located on the semiconductor substrate, and then blowing gas onto the surface of the semiconductor substrate. Separating the semiconductor substrate from the growth substrate, holding the semiconductor substrate by the substrate holder, and transporting the semiconductor substrate in this state. 8. The method of manufacturing a semiconductor substrate according to claim 7, wherein the gas blown onto the surface of the semiconductor substrate is hydrogen gas or a mixed gas of hydrogen gas and an inert gas.