JP2009155115A - Apparatus for producing single crystal silicon - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for producing single crystal silicon by which a seed crystal can simply be held in such a state that the seed crystal is exactly aligned with a polycrystalline silicon rod. <P>SOLUTION: In the apparatus for producing single crystal silicon, the seed crystal 6 held by a seed crystal holder 7 and a polycrystalline silicon rod S1 held by a polycrystal holder 5 are arranged oppositely to each other in a housing, and the polycrystalline silicon rod is fusion-bonded to the seed crystal 6 while being heated and melted and grown into a single crystal. In the seed crystal holder 7, a housing hole 22 for holding one end part of the seed crystal 6 in an upright posture is formed, a fixing screw 26 for fixing one end part of the seed crystal 6 housed in the housing hole 22 is arranged orthogonally to the axis line of the housing hole 22, and the inner peripheral surface of the housing hole 22 is formed into a tapered face 22a having the gradually increasing diameter toward its opening 21. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a single crystal silicon manufacturing apparatus, and more particularly to a single crystal silicon manufacturing apparatus that grows a polycrystalline silicon rod into a single crystal by FZ method.

  Conventionally, what is shown by patent document 1 is known as a single crystal silicon manufacturing apparatus using this kind of FZ (float zone) method. This single crystal silicon manufacturing apparatus includes a housing in an inert gas atmosphere, and a polycrystalline holder installed on an upper drive shaft (positioning rod) in the housing and holding a polycrystalline silicon rod as a sample at the lower end thereof (Material holder), a seed crystal holder installed on the lower drive shaft (positioning rod) and holding a silicon single crystal seed crystal at the upper end thereof, and a high frequency induction heating coil provided in an intermediate portion of the housing, The polycrystalline silicon rod as a raw material is held in the upper polycrystalline holder, and the seed crystal holder is held with the seed crystal of the silicon single crystal. After melting one end and fusing it to the seed crystal, the polycrystalline silicon rod is relatively moved in the axial direction while rotating relative to the high frequency induction heating coil. , While sequentially zone melting the polycrystalline silicon rod in the axial direction, is to produce a rod of single crystal silicon.

In addition, the polycrystalline holder has a lower end for holding the polycrystalline silicon rod in a suspended state and an upper end connected to the upper drive shaft, and the seed crystal holder has the seed crystal in an upward posture. It has an upper end portion to be held and a lower end portion connected to the lower drive shaft. These both holders are the same so that the polycrystalline silicon rod is arranged vertically above the seed crystal held by the seed crystal holder. It is arranged on the axis. The upper drive shaft and the lower drive shaft are driven up and down and rotated, respectively.
Japanese Patent Laid-Open No. 7-10681

  By the way, the polycrystalline silicon rod and the seed crystal need to be arranged on the same axis exactly, but the seed crystal is rotated at a high speed when fused to the lower end portion of the molten polycrystalline silicon rod. At that time, it is firmly fixed by a set screw so that no slip or the like occurs with the seed crystal holder. In this case, since the set screw is provided in a direction orthogonal to the axis of the seed crystal holder, the seed crystal is pressed in the radial direction. At this time, the seed crystal is easily displaced from the axis of the storage hole. Subtle adjustment work is required between fixing the seed crystal and aligning the core with the polycrystalline silicon rod.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a single crystal silicon manufacturing apparatus that can easily hold a seed crystal in a state where it is accurately aligned with a polycrystalline silicon rod.

  In the single crystal silicon production apparatus of the present invention, a seed crystal held in a seed crystal holder and a polycrystalline silicon rod held in the polycrystalline holder are arranged opposite to each other in a housing, and the polycrystalline silicon rod is heated and melted. An apparatus for producing single crystal silicon that is fused to a seed crystal to grow into a single crystal while the seed crystal holder is formed with a storage hole that holds one end of the seed crystal in an upright posture, and the storage A set screw for fixing one end of the seed crystal accommodated in the hole is provided orthogonal to the axis of the accommodation hole, and the inner peripheral surface of the accommodation hole is a tapered surface that gradually increases in diameter toward the opening. It is characterized by that.

  That is, the inner peripheral surface of the accommodation hole of the seed crystal holder is a tapered surface, and the seed crystal is held by the tapered surface. If the storage hole is straight, when the seed crystal is stored and fastened with a set screw, the seed crystal can easily move in the horizontal direction within the clearance range. It is difficult for the circumference to contact the tapered surface and move in the left-right direction, and therefore, the centering operation with the polycrystalline silicon rod is facilitated. In addition, when the seed crystal is rotated, the seed crystal is held on the tapered surface all around, so that it is difficult to slip.

  In the single crystal silicon manufacturing apparatus of the present invention, the tapered surface has an angle formed with the axis of the storage hole set to 10 to 25 °. By forming the tapered surface within this angular range, the seed crystal can be stably held in an upright posture and an appropriate frictional force can be applied even during rotation.

  Moreover, the single crystal silicon manufacturing apparatus of this invention WHEREIN: The surface roughness of the said taper surface is 10-200 micrometers in average roughness (Ra), It is characterized by the above-mentioned. That is, by setting the surface roughness within this range, the frictional force between the tapered surface of the storage hole and the seed crystal increases, and slipping during rotation can be reliably prevented.

  According to the single crystal silicon manufacturing apparatus of the present invention, by making the accommodation hole of the seed crystal holder into a tapered surface, the entire circumference of the seed crystal is in contact with the tapered surface and hardly moves in the left-right direction. The centering work becomes easier. Further, when the seed crystal is rotated, it is difficult to slip because the tape is held on the entire circumference of the seed crystal. Therefore, the seed crystal can be stably held in an upright posture, and high-quality single crystal silicon can be manufactured.

  Hereinafter, an embodiment of a single crystal silicon manufacturing apparatus according to the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of a single crystal manufacturing apparatus 100 according to an embodiment. In this figure, reference numeral 1 denotes a housing filled with an inert gas (argon gas). An upper drive shaft 2 that is rotationally driven and driven up and down in the vertical direction is provided at the center of the upper wall 1A of the housing 1, and the bottom 1B of the housing 1 has the same axis as the upper drive shaft 2. A lower drive shaft 3 that is rotationally driven and driven up and down in the vertical direction is provided so as to face each other. At the lower end of the upper drive shaft 2 is provided a polycrystalline holder 5 for holding a polycrystalline silicon rod S1 as a sample via a suspension 4 made of molybdenum wire, and at the upper end of the lower drive shaft 3 Is provided with a seed crystal holder 7 for holding a seed crystal 6 of silicon single crystal.

  Between the polycrystalline holder 5 and the seed crystal holder 7 in the housing 1, a high frequency induction heating coil 8 and a heat generating ring 9 covered with quartz are provided. The high frequency induction heating coil 8 is formed in a ring disk shape as a whole, and is held horizontally by a support bar 10 supported on the side wall 1 </ b> C of the housing 1. As shown in FIG. 2, the heat generating ring 9 is formed in a ring shape as a whole, and is horizontally held at a position above the high frequency induction heating coil 8 by a support shaft 11 suspended from the upper wall 1 </ b> A of the housing 1. .

  The support shaft 11 is supported on the upper wall 1A of the housing 1 so as to be able to rotate and move up and down, and an operation means 11A such as a lever is provided at an upper end portion thereof. By operating the operation means 11A, The heating ring 9 held at its lower end is slightly moved up and down, and reciprocates between a heating position disposed between the polycrystalline holder 5 and the seed crystal holder 7 and a retreating position spaced laterally from the heating position. It can be moved.

On the other hand, the seed crystal holder 7 is formed of tantalum (Ta) in a tubular shape as a whole as shown in FIGS. 2 and 3, and gradually increases in diameter toward the upper end opening 21 in most parts except the lower end portion thereof. A conical upper storage hole 22 is formed, and a straight cylindrical lower storage hole 23 is formed at the lower end thereof. These storage holes 22 and 23 are arranged on the same axis C ₁ , the seed crystal 6 is stored in the upper storage hole 22, and the lower storage hole 23 is made of quartz fixed to the tip of the lower drive shaft 3. A rod-like support member 24 is accommodated.

The seed crystal 6 held by the seed crystal holder 7 is formed in a rod shape as a whole, but has a conical shape with tapered ends at the upper end 6a and the lower end 6b from the center in the length direction. Is formed. The support member 24 is formed in a straight cylindrical shape. Then, attach the seed crystal holder 7 on the support member 24, by a state of accommodating the lower end 6b of the seed crystal 6 into the upper receiving hole 22, the axis C ₂ of the seed crystal 6 thereabove multi so that the can be placed on the axis C ₃ and collinear polycrystalline silicon rod S1, held by the crystal holder 5.

  Further, four screw holes 25 along the radial direction are provided at both ends of the seed crystal holder 7 at intervals of 90 ° in the circumferential direction. These screw holes 25 respectively penetrate the wall of the seed crystal holder 7 so as to communicate with the internal upper storage hole 22 and lower storage hole 23. Then, the seed crystal 6 stored in the upper storage hole 22 is fixed by screwing a set screw 26 from the upper screw hole 25, and the support member 24 stored in the lower storage hole 23 is fixed to the lower screw hole 25. It is the structure fixed by screwing.

The tapered surface 22a which forms the inner peripheral surface of the upper receiving hole 22 of the seed crystal holder 7, together with the angle θ formed between the axis C ₁ of the upper housing bore 22 is set to 10 to 25 °, The surface roughness is 10 to 200 μm in terms of average roughness (Ra). If the angle of the taper surface 22a is larger than 25 °, the posture of the seed crystal 6 is not stabilized, so that the so-called “sitting is bad” state, the seed crystal 6 is easily slipped during rotation, and is smaller than 10 °. Misalignment is likely to occur. More preferably, the angle is 17 to 18 °. Further, when the surface roughness is 10 to 200 μm, the seed crystal 6 can be held with an appropriate frictional force during rotation, and the posture can be accurately maintained.

  Further, in the outer peripheral portion of the center portion in the length direction of the seed crystal holder 7, concave portions 27 are respectively formed at symmetrical positions separated by 180 ° in the circumferential direction. These concave portions 27 are used to place the tip of a tool such as pliers when the seed crystal holder 7 is fixed to the support member 24 or the seed crystal 6 is held in the accommodation hole 22, and the cross section is rectangular. A flat surface 27a is formed in parallel with the radial direction so that the tip of the tool can come into contact therewith.

A method of manufacturing single crystal silicon using the single crystal manufacturing apparatus 100 configured as described above will be described below in the order.
(1) The seed crystal 6 is attached to the seed crystal holder 7 and the hanging tool 4 is attached to the polycrystalline silicon rod S1 as a sample so that the polycrystalline silicon rod S1 is supported by the polycrystalline holder 5. At this time, by inserting the lower end portion 6 b of the seed crystal 6 into the upper accommodation hole 22 of the seed crystal holder 7, the tapered surface 22 a of the upper accommodation hole 22 comes into contact with the outer peripheral surface of the seed crystal 6. By automatically aligning the core and fixing it with the set screw 26 in the housed state, the center is maintained.
(2) The heat generating ring 9 is arranged at a position (heating position) between the seed crystal 6 and the polycrystalline silicon rod S1 arranged coaxially in this way.
(3) Lower the upper drive shaft 2 to pass the polycrystalline silicon rod S1 as a sample through the heating ring 9, and the polycrystalline silicon rod S1 so that the lower end of the sample is close to the upper side of the high frequency induction heating coil 8 Position.
(4) The door (not shown) of the housing 1 is closed to make the inside hermetically sealed and filled with an inert gas.

(5) By driving the high frequency induction heating coil 8, the heat generating ring 9 is heated, and the polycrystalline silicon rod is preheated by the radiant heat. This preheating is performed until it is confirmed that the heating ring 9 is red.
(6) The upper drive shaft 2 is raised to separate the polycrystalline silicon rod S1 from the seed crystal 6 and thereby move the heating ring 9 from the gap formed between the polycrystalline silicon rod S1 and the seed crystal 6. Thus, the housing 1 is retracted to a position near the side wall 1C (retracted position). Thereafter, the upper drive shaft 2 is lowered, and the polycrystalline silicon rod S1 is lowered to the vicinity of the high frequency induction heating coil 8.

(7) Increase the output of the high frequency induction heating coil 8 to melt the tip of the polycrystalline silicon rod S1.
(8) The lower drive shaft 3 is raised to bring the seed crystal 6 closer to the polycrystalline silicon rod S1. When the tip of the polycrystalline silicon rod S1 is completely melted, the seed crystal 6 and the polycrystalline silicon rod S1 are brought into contact with each other to transfer the heat of the polycrystalline silicon rod S1 to the seed crystal 6 and melt the seed crystal 6 To do.
(9) The lower drive shaft 3 is rotationally driven to rotate the seed crystal 6 at a high speed.
(10) The molten part and the seed crystal 6 are sufficiently blended while adjusting the shape of the molten part at the lower end of the polycrystalline silicon rod S1.
(11) By moving the upper drive shaft 2 and the lower drive shaft 3 synchronously along the axial direction, the molten portion of the polycrystalline silicon rod S1 is moved relative to the high-frequency induction heating coil 8 in the vertical direction, Thereby, the single crystal silicon S2 is grown on the lower drive shaft 3.
(12) When the single crystal silicon S2 is sufficiently formed, the driving of the upper drive shaft 2, the lower drive shaft 3, and the high frequency induction heating coil 8 is stopped. Thereafter, the formed single crystal silicon is taken out and cooled by a rapid cooling device.

According to the single crystal manufacturing apparatus 100 as described above, the conical outer peripheral surface of the seed crystal 6 is inserted by inserting the seed crystal 6 having both ends 6a and 6b into a conical shape into the upper storage hole 22 of the seed crystal holder 7. Can contact the taper surface 22a of the storage hole 22 over the entire circumference so that the axes C ₁ and C ₂ of both can be made to coincide with each other accurately, so that the axis C ₂ of the seed crystal 6 is arranged above the axis C _2. the axis C ₃ of the polycrystalline silicon rods are matched exactly. That is, by inserting the seed crystal 6 into the storage hole 22, the axes C ₁ and C ₂ are stored in a state where they coincide with each other, and the core C _{3 is} aligned with the axis C ₃ with the polycrystalline silicon rod S 1 thereabove. As a result, the working time for attaching the seed crystal 6 can be greatly shortened. Then, by fixing the set screw 26 in this stored state, the entire circumference of the seed crystal 6 is held by the taper surface 22a. Can be securely fixed.

  The seed crystal 6 may be rotated during the single crystal silicon growing operation. However, since the seed crystal 6 is held by the taper surface 22a of the accommodation hole 22 all around, the slip is generated. Therefore, the center alignment state can be reliably maintained, and therefore, high quality single crystal silicon can be manufactured.

  In addition, this invention is not limited to the said embodiment, A various change can be added in the range which does not deviate from the meaning of this invention. For example, in the seed crystal holder 7 of one embodiment, the upper housing hole 22 is formed on the tapered surface 22a that continues to the opening, but at least a portion of the tapered surface that can contact the entire circumference of the seed crystal is formed. The vicinity of the opening may be a straight cylindrical shape. In addition, the seed crystal inserted into the storage hole is fixed with four set screws, but may be fixed with three set screws.

It is a schematic sectional drawing which shows the whole single crystal manufacturing apparatus in one Embodiment of this invention. It is a longitudinal cross-sectional view which expands and shows the state which hold | maintained the seed crystal in the seed crystal holder in FIG. It is a perspective view which shows the external appearance of the seed crystal holder of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Housing 2 Upper drive shaft 3 Lower drive shaft 4 Hanging tool 5 Polycrystalline holder 6 Seed crystal 6a Upper end 6b Lower end (one end)
7 seed crystal holder 8 high frequency induction heating coil 9 heating ring 10 support rod 11 support shaft 11A operation means 21 opening 22 upper storage hole (storage hole)
22a Tapered surface 23 Lower storage hole 24 Support member 25 Screw hole 26 Set screw S1 Polycrystalline silicon rod

Claims (3)

In the housing, the seed crystal held in the seed crystal holder and the polycrystalline silicon rod held in the polycrystalline holder are arranged to face each other, and the polycrystalline silicon rod is fused to the seed crystal while being heated and melted. A single crystal silicon manufacturing apparatus for growing a crystal,
The seed crystal holder has a storage hole for holding one end of the seed crystal in an upright posture, and a set screw for fixing the one end of the seed crystal stored in the storage hole is perpendicular to the axis of the storage hole. Provided,
The single crystal silicon manufacturing apparatus according to claim 1, wherein an inner peripheral surface of the storage hole is a tapered surface that gradually increases in diameter toward the opening.   The single crystal silicon manufacturing apparatus according to claim 1, wherein the taper surface is set to have an angle of 10 to 25 ° with the axis of the storage hole.   3. The single crystal silicon manufacturing apparatus according to claim 1, wherein the taper surface has an average roughness (Ra) of 10 to 200 μm.

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