JP2010037142A - Method and apparatus for producing single crystal silicon - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus for producing single crystal silicon by which the productivity in production and the material yield in processing of products can be improved by growing a single crystal silicon in such a manner that the cross section of the single crystal silicon becomes a polygonal shape. <P>SOLUTION: The apparatus 1 for producing the single crystal silicon T is provided with: a seed rotation control means; a crucible rotation control means; and a seed pulling rate control means for controlling the pulling rate of a seed S within a range of 0.4-2.0 mm/min. Wherein, a seed S, prepared so that the arrangement of the crystal lattice of the contact surface S1 with a silicon melt M becomes (100) direction, is used. Thereby, a single crystal silicon T having a cross section with approximately a tetragon is grown. Similarly, when the arrangement of the crystal lattice is made (111) or (110), the shape of the cross section of the obtained single crystal silicon T is made triangle or hexagonal. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method and an apparatus for manufacturing single crystal silicon.

Single crystal silicon used for a semiconductor substrate or the like is generally manufactured by the Czochralski method (hereinafter referred to as CZ method).
In the CZ method, polycrystalline silicon is placed in a quartz crucible placed in a high pressure-tight airtight chamber, the polycrystalline silicon in the quartz crucible is heated and melted, and seeds are placed on a seed chuck placed above the quartz crucible ( A seed crystal is attached and the seed is immersed in a silicon melt in a quartz crucible, and the seed is pulled while the seed and the quartz crucible are rotated to grow single crystal silicon (for example, see Patent Document 1). .)

In such a method for producing single crystal silicon in the CZ method, when obtaining large single crystal silicon, the seed pulling speed and the like are controlled so that the cross section perpendicular to the longitudinal direction of the single crystal silicon becomes a circle with a large diameter. It was.
In recent years, many polycrystalline silicons have been manufactured. In the manufacturing of polycrystalline silicon, for example, manufacturing by casting as shown in Patent Document 2 is performed.
JP 2001-278696A JP-A-12-290096

However, since the single crystal silicon manufactured by the above method is substantially cylindrical, the shape when sliced into a silicon wafer is circular. For example, when manufacturing a rectangular product such as a solar cell, the outer periphery It is necessary to cut and remove the material into a rectangular shape. As a result, a lot of milling material is generated and the material yield is lowered. When silicon is cut, there is a problem that it is difficult to recycle because SiO2 generated and oxidized is mixed.
In addition, if a portion corresponding to the above-mentioned end material is formed on the outer periphery of the single crystal silicon, there is a problem in that the crystal growth in the quartz crucible shortens the length of the single crystal silicon and decreases the productivity.

  The present invention has been made in consideration of such circumstances. By growing single crystal silicon so that the cross section of the single crystal silicon becomes a polygon, the productivity in manufacturing and the material yield in product processing are improved. An object of the present invention is to provide a method and an apparatus for manufacturing single crystal silicon that can be improved.

In order to achieve the above object, the present invention proposes the following means.
According to the first aspect of the present invention, a seed is immersed in a silicon melt stored in a quartz crucible disposed in an airtight chamber, and the single crystal silicon is pulled up while rotating the seed relative to the quartz crucible. A method for producing single crystal silicon by a CZ method to be grown, comprising controlling a crystal lattice arrangement on a contact surface of the seed with the melt to form a polygonal cross section perpendicular to the pulling direction. Features.

According to the method for producing single crystal silicon according to the present invention, the arrangement of the crystal lattice on the contact surface with the seed melt immersed in the silicon melt is controlled in accordance with the cross-sectional shape of the single crystal silicon to be grown. It is possible to manufacture single crystal silicon having a cross-sectional shape corresponding to the arrangement of crystal lattices. As a result, the length of single crystal silicon in crystal growth can be increased.
Further, by forming single crystal silicon into a polygonal column, it is not necessary to largely remove the outer periphery when processing into a product, and as a result, the material yield can be improved.

  The invention according to claim 2 is the method for producing single crystal silicon according to claim 1, wherein the seed pulling rate is set to 0.4 mm / min to 2.0 mm / min.

  According to the method for manufacturing single crystal silicon according to the present invention, it is possible to grow a polygonal single crystal silicon crystal along the crystal lattice arrangement by lowering the seed from a normal pulling rate. .

  A third aspect of the invention is a method for producing single crystal silicon according to the first or second aspect, wherein the quartz crucible is rotated in the same direction as the seed.

  According to the method for producing single crystal silicon according to the present invention, since the rotation of the seed and the quartz crucible is made in the same direction, the fluid resistance of the melt on the outer periphery of the seed is reduced, and the flow of the melt on the outer periphery of the seed is smooth. Therefore, stable crystal growth can be achieved on the outer periphery of the seed.

  According to a fourth aspect of the present invention, a seed is immersed in a silicon melt stored in a quartz crucible disposed in an airtight chamber, and the seed is pulled up while rotating relative to the quartz crucible to obtain single crystal silicon. An apparatus for producing single crystal silicon to crystallize, wherein a seed rotation control means for controlling the rotation direction and rotation speed of the seed, a crucible rotation control means for controlling the rotation direction and rotation speed of the quartz crucible, and the seed And a seed pulling speed control means capable of controlling the pulling speed from 0.4 mm / min to 2.0 mm / min.

According to the single crystal silicon manufacturing method or single crystal silicon manufacturing apparatus according to the present invention, single crystal silicon having a polygonal cross section perpendicular to the longitudinal direction can be manufactured.
As a result, the material yield at the time of crystal growth and product molding can be improved.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram schematically showing an outline of a single crystal silicon manufacturing apparatus according to an embodiment of the present invention. Reference numeral 1 indicates a single crystal silicon manufacturing apparatus.

  The single crystal silicon manufacturing apparatus 1 includes a pressure-tight and airtight chamber 10, a quartz crucible 15, a seed chuck 17, a heater 19, a crucible support 21, and a seed chuck drive mechanism 30, and is in a reduced pressure state. In the chamber 10, the seed S attached to the seed chuck 17 is immersed in the silicon melt M stored in the quartz crucible 15 and pulled up while rotating to grow single crystal silicon T.

  The chamber 10 includes a main chamber 11, a top chamber 12 connected to the top of the main chamber 11, and a pull chamber 13 connected to the top of the top chamber 12. The main chamber 11 is erected on the bottom 11A and the bottom 11A. The quartz crucible 15 is disposed at the center, and a vacuum pump (not shown) is connected to the exhaust hole 11D so that the inside of the chamber 10 can be depressurized or evacuated. .

  Further, when the spill tray 14 is disposed at the bottom portion 11A of the main chamber 11, and the quartz crucible 15 is broken and the silicon melt M flows out, the silicon melt M directly contacts the bottom portion 11A. It is possible to prevent the chamber from being damaged.

  The pull chamber 13 is formed in a substantially cylindrical shape, has a space for storing the pulled single crystal silicon T, and is connected to the main chamber 11 by the top chamber 12.

  The quartz crucible 15 can hold bulk polycrystalline silicon, which is a raw material of the single crystal silicon T, in the recess of the quartz crucible 15 and can store the silicon melt M generated by heating and melting the polycrystalline silicon. And is stored in a graphite crucible 16.

  The graphite crucible 16 is integrally formed by being held by a pedestal 21 </ b> C disposed on the upper surface of the crucible support base 21, and the crucible support base 21 has a support portion 21 </ b> A at the center of the bottom portion 11 </ b> A of the main chamber 11. And inserted into a through hole 11H formed through the bottom portion 11A and the spill tray 14, and can be rotated and moved up and down relatively with respect to the main chamber 11.

  In addition, a cylindrical heater 19 is disposed around the graphite crucible 16 and a cylindrical heat insulating cylinder 22 is disposed outside the heater 19. The heat insulating cylinder 22 includes an inner heat insulating cylinder 22A made of cylindrical graphite and an inner heat insulating cylinder 22A. The outer heat insulating tube 22B made of cylindrical porous graphite is disposed outside the heat insulating tube 22A, and the heat insulating tube 22 is a disc in which a hole having an inner diameter substantially the same as the inner diameter of the inner heat insulating tube 22A is formed. A disc-shaped upper ring 22D having a hole having an inner diameter substantially the same as the inner diameter of the inner heat retaining cylinder 22A is disposed on the upper lower ring 22C.

The lower side of the heater 19 is fixed to the electrode joint 19A with bolts 19B, and the electrode joint 19A is connected to a power source (not shown) via a graphite electrode 19C disposed in a through hole formed in the spill tray 14.
A flow pipe 24 is attached to the upper end of the heat insulating cylinder 22 via an upper ring 22 </ b> D and an adapter 23.
The flow tube 24 is an inverted frustoconical hollow cylinder whose upper end opening is larger in diameter than the lower end opening, and is made of graphite or SiC.

The seed chuck 17 has a carbon chuck portion 17A having a tip side formed of carbon, and a hole 17B is formed in the center of the tip surface of the carbon chuck portion 17A from the tip side to the base end side. A seed (seed crystal) S is inserted, and the seed S is inserted into a notch SC formed on the outer periphery through a hole formed in the carbon chuck portion 17A, and the seed S is inserted into the carbon chuck portion 17A. It is supposed to be fixed to.
The seed chuck 17 is connected to the wire W at the base end side, and the seed S can be rotated and moved up and down relatively with respect to the main chamber 11 by connecting the wire W to the seed chuck drive mechanism 30.

  The seed chuck drive mechanism 30 is provided in the upper part of the pull chamber 13, and can be rotated relative to the pull chamber 13 with the pulley 31 connected to the proximal end of the wire W and wound, and the wire W as the rotation axis O. A rotation drive unit 32, and the pulley 31 winds up the wire W so that the seed chuck 17 moves up and down, and the rotation drive unit 32 rotates so that the seed chuck 17 turns around the wire W. It has become.

  For example, the seed S has a crystal lattice arrangement (100) as shown in FIG. 3A, and the single crystal silicon T is deposited by depositing the single crystal silicon T using the seed S having such a configuration. A single crystal silicon T having a quadrangular (polygonal) cross section perpendicular to the longitudinal direction is deposited.

  The single crystal silicon manufacturing apparatus 1 includes a control unit 50, and the control unit 50 is configured to be able to control the rotation of the crucible support base 21 and the rotation and elevation of the seed chuck drive mechanism 30. The rotation direction and rotation speed, the rotation direction and rotation speed of the seed chuck 17 by the rotation drive unit 32 in the seed chuck drive mechanism 30, and the raising and lowering and lifting (up) speed of the seed chuck 17 by the pulley 31 can be controlled. ing.

  The control unit 50 includes, for example, a first inverter 51, a second inverter 52, a third inverter 53, and a calculation unit 54, and includes a first inverter 51, a second inverter 52, and a third inverter. The inverter 53 is configured to send a drive signal based on an instruction signal from the calculation unit 54.

For example, the control unit 50 can control the rotation direction and rotation speed of the quartz crucible by changing the frequency of the first inverter 51 and controlling the rotation direction and rotation speed of the motor M1 that rotates the crucible support base 21. The rotational speed of the crucible support 21 can be adjusted from 1.0 rpm to 30 rpm, for example.
The first inverter 51 and the motor M1 constitute a crucible rotation control means.

Similarly, the rotation axis O of the seed chuck 17 is controlled by changing the frequency of the second inverter 52 and controlling the rotation direction and the rotation speed of the motor M2 that rotates the rotation drive unit 32 of the seed chuck drive mechanism 30. The rotation direction (right rotation, left rotation) and rotation speed of the surroundings can be adjusted, and the rotation speed of the seed chuck 17 can be adjusted from 0.5 rpm to 15 rpm.
The second inverter 52 and the motor M2 constitute seed rotation control means.

Further, by changing the frequency of the third inverter 53 and controlling the rotation direction and the number of rotations of the motor M3 that rotates the pulley 31 around which the wire W is wound, the raising / lowering direction and the pulling speed of the seed chuck 17 can be adjusted. The pulling-up speed of the seed chuck 17 can be adjusted from 0.01 rpm to 10 rpm.
The third inverter 53 and the motor M3 constitute seed pulling speed control means.

Next, the operation of the single crystal silicon manufacturing apparatus 1 will be described.
(1) First, bulk polycrystalline silicon as a raw material is filled in a quartz crucible 15, and the quartz crucible 15 is heated by a heater 19 to dissolve the polycrystalline silicon to obtain a silicon melt M at 1420 ° C. The silicon melt M in the vicinity of the portion to be immersed is brought into a supercooled state.
(2) Next, the seed S is inserted and fixed in the carbon chuck portion 17A.
The seed S in this embodiment is prepared so that the crystal lattice arrangement of the contact surface S1 with the silicon melt M is in the (100) direction.
The crystal lattice arrangement is prepared by, for example, analyzing the crystal lattice arrangement by X-ray diffraction and forming the contact surface S1 based on the result.
(3) Next, the seed chuck drive mechanism 30 is driven, the seed chuck 17 is lowered, the seed S is immersed in the silicon melt M, and the seed S is adapted to the silicon melt M.
(4) When the seed S becomes familiar with the silicon melt M, the seed chuck 17 is raised at a speed of 0.4 mm / min to 2.0 mm / min while rotating rightward in plan view at 8 rpm, for example.
At this time, the quartz crucible 15 is rotated to the right in plan view like the seed S, and the rotation speed is, for example, 90 to 110% of the rotation speed of the seed.
(5) By pulling up the seed S and depositing the single crystal silicon T in this way, the single crystal silicon T having a substantially rectangular cross section grows.

  According to the method for manufacturing single crystal silicon T according to this embodiment, the cross section of single crystal silicon T on which the crystal lattice array on the contact surface of seed S immersed in silicon melt M with silicon melt M is grown. Since the control is performed according to the shape, the single crystal silicon T having a square cross section corresponding to the arrangement of the crystal lattice can be manufactured.

As a result, it is possible to increase the length of the single crystal silicon T in the crystal growth process, and to improve productivity.
In addition, by forming the single crystal silicon T into a quadrangular column, it is not necessary to greatly cut the outer periphery when processing a rectangular product such as a solar battery, and as a result, the material yield can be improved.

  Also, the single crystal silicon T having a polygonal cross section along the crystal lattice arrangement is manufactured by pulling up the seed S at a pulling rate of 0.4 mm / min to 0.8 mm / min, which is slower than the normal pulling rate. Can do.

  Further, since the rotation of the seed S and the quartz crucible 15 is in the same direction, the fluid resistance of the silicon melt M on the outer periphery of the seed S becomes small, and the flow of the silicon melt M on the outer periphery of the seed S becomes smooth. The single crystal silicon T can be stably deposited on the outer periphery of the seed S.

  According to the single crystal silicon manufacturing apparatus 1 according to the above-described embodiment, the single-crystal silicon T having a polygonal column can be manufactured stably.

  In addition, about the technical matter described in said embodiment, it is possible to add a various change in the range which does not deviate from the meaning of invention.

  For example, in the above embodiment, the rotation directions and rotation speeds of the motors M1, M2, and M3 are controlled by the inverters 51, 52, and 53, and the rotation direction of the quartz crucible 15 via the pulley 31, the rotation drive unit 32, and the like. In the above description, the horizontal rotation direction and rotation speed of the seed S and the pulling speed of the seed S are adjusted. However, the control means, the drive means, and the transmission means can be freely selected. .

  In the above embodiment, the case where the pulling speed by the pulley 31 is controlled from 0.4 mm / min to 0.8 mm / min has been described. However, the seed S may be pulled by a pulling speed outside this speed range. .

  In the above-described embodiment, the case where both the seed S and the quartz crucible 15 are rotated to the right in plan view has been described. For example, both the seed S and the quartz crucible 15 can be rotated to the left. It is also possible to rotate one of them to the opposite side with the right rotation and the other left rotation.

  In the above embodiment, the case where the crystal lattice arrangement is (100) and the cross-sectional shape of the single crystal silicon T is crystal-grown has been described. For example, the crystal lattice arrangement is (111). The cross-sectional shape of the single crystal silicon T is set to a triangle, or the cross-sectional shape of the single crystal silicon T is set to (110) and the cross-sectional shape of the single crystal silicon T is a hexagon. It is also possible to manufacture single crystal silicon T having the same.

It is a longitudinal cross-sectional view which shows the manufacturing apparatus of the single crystal silicon which concerns on one Embodiment of this invention. It is a figure explaining the seed and the manufacturing method of single crystal silicon concerning one embodiment of the present invention. It is a figure which shows the arrangement | sequence of the crystal lattice of the surface by the side of the melt which concerns on this invention, (A) is a square cross section, (B) is a hexagonal cross section, (C) is a single crystal silicon with a triangular cross section. It is a figure which shows the crystal lattice for manufacturing.

Explanation of symbols

M silicon melt S seed S1 contact surface T single crystal silicon 1 single crystal manufacturing apparatus 10 chamber (airtight chamber)
15 Quartz crucible 50 Control part

Claims (4)

Single crystal silicon by CZ method in which a seed is immersed in a silicon melt stored in a quartz crucible disposed in an airtight chamber, and the seed is pulled up while rotating relative to the quartz crucible to grow single crystal silicon. A manufacturing method of
A method for producing single crystal silicon, comprising: controlling a crystal lattice arrangement at a contact surface of the seed with the melt to form a polygonal cross section perpendicular to the pulling direction. A method for producing single crystal silicon according to claim 1,
A method for producing single crystal silicon, wherein the seed pulling rate is 0.4 mm / min to 2.0 mm / min. A method for producing single crystal silicon according to claim 1 or 2,
A method for producing single crystal silicon, wherein the quartz crucible is rotated in the same direction as the seed. An apparatus for producing single crystal silicon, wherein a seed is immersed in a silicon melt stored in a quartz crucible disposed in an airtight chamber, and the seed is pulled up while rotating relative to the quartz crucible to crystallize single crystal silicon. Because
Seed rotation control means for controlling the rotation direction and rotation speed of the seed;
Crucible rotation control means for controlling the rotation direction and rotation speed of the quartz crucible;
An apparatus for producing single crystal silicon, comprising: a seed pulling speed control means capable of controlling the speed of pulling up the seed from 0.4 mm / min to 2.0 mm / min.

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