JP2010006657A - Silicon single crystal production apparatus and silicon single crystal production method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a silicon single crystal production apparatus and a silicon single crystal production method which each reduces the collision of a silicon solid raw material against a crucible and suppresses the adhesion of a silicon melt to a raw material filling container. <P>SOLUTION: A crucible 4 which melts a silicon solid raw material, a raw material filling container 18 being a feed apparatus which feeds the solid raw material and containing a raw material feed part 19 which feeds the solid raw material into the crucible 4, and a raw material feed part cover which covers the raw material feed part 19 and tapers toward an opening formed on the crucible side 4. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a silicon single crystal manufacturing apparatus and a silicon single crystal manufacturing method used in the multi-pooling method of the Czochralski method.

  In general, a silicon single crystal is grown by the Czochralski method (CZ method).

  Conventionally, a multi-pooling method is known as a method for reducing the production cost of a silicon single crystal by the Czochralski method (see Non-Patent Document 1). This is a method in which a single crystal having a target length is pulled up from a crucible, an additional supply of silicon solid material corresponding to the weight to be pulled is supplied, and the same single crystal pulling is repeated again. By this method, a plurality of single crystals can be produced from a quartz crucible that can be used only once, and the production yield can be improved and the crucible cost can be reduced.

  As such a method, for example, a silicon solid raw material supply device having a conical bottom lid at the tip of a raw material filling container containing a silicon solid raw material is known (see Patent Document 1).

In addition, in order to produce polycrystalline silicon, a silicon solid material supply device is known in which a funnel is provided with a distance from a raw material filling container containing a silicon solid material (see Patent Document 2).
JP 2006-89294 A Japanese Patent Laid-Open No. 10-139586 Semiconductor Silicon Crystal Technology, Fumio Shimura 1989

  However, in the invention of Patent Document 1, there is a tendency that the solid silicon raw material collides with the inner wall surface of the crucible and impurities are mixed from the crucible into the silicon solid raw material.

  Also in the invention of Patent Document 2, there is a tendency that liquid splash to the raw material filling container occurs on the melt surface at the time of filling the solid raw material of silicon, and the silicon melt adheres to the raw material filling container and the raw material filling container deteriorates. there were.

  Accordingly, the present invention has been completed in view of the above-mentioned problems in the prior art, and its purpose is to reduce the collision of the silicon solid material with the crucible and to adhere the silicon melt to the material filling container. An object of the present invention is to provide a silicon single crystal manufacturing apparatus and a silicon single crystal manufacturing method for suppressing the above.

  The silicon single crystal manufacturing apparatus of the present invention is a silicon single crystal manufacturing apparatus, a crucible for melting a solid raw material of silicon, and a supply apparatus for supplying the solid raw material, wherein the solid raw material is supplied to the crucible. A supply device including a raw material filling container including a raw material supply unit to be supplied, and a raw material supply unit cover that covers the raw material supply unit and tapers toward an opening provided on the crucible side.

  The raw material supply unit cover is preferably made of molybdenum, tungsten, or silicon carbide.

  Moreover, it is desirable that the supply device is disposed so that the center of the opening coincides with the center of the crucible when viewed from above.

  The method for producing a silicon single crystal according to the present invention is a method for producing a silicon single crystal including a supply step of supplying a silicon solid raw material to a crucible, wherein the supply step includes a silicon solid raw material filled in a raw material filling container. A step of discharging from the raw material supply unit; a step of covering the raw material supply unit and dropping the solid raw material into the crucible via a raw material supply unit cover having an opening tapered toward the crucible; including.

  Since the silicon single crystal manufacturing apparatus of the present invention has the above-described configuration, the crucible for the raw material filling container can be used even if liquid splashing occurs on the raw material filling container on the melt surface during filling of the silicon solid raw material. Since the raw material supply part arranged on the side is covered with the raw material supply part cover, deterioration of the raw material filling container caused by the adhesion of the silicon melt can be suppressed. In addition, since the raw material supply unit cover is tapered toward the opening, diffusion of the solid silicon raw material to be released can be reduced, and collision of the solid silicon raw material with the inner wall surface of the crucible can be suppressed. .

  Further, since the raw material supply unit cover is made of heat-resistant molybdenum, tungsten, or silicon carbide, it can be used for a long period of time, thereby sufficiently protecting the raw material filling container from the silicon melt.

  Further, since the supply device is disposed so that the center of the crucible and the center of the opening coincide with each other when viewed from above, the solid material of silicon falls near the center of the crucible, The collision of the silicon solid raw material with the inner wall surface of the crucible or the heat shield shield can be suppressed.

  According to the method for producing a silicon single crystal of the present invention, since the above-described steps are performed, it is possible to suppress contamination of impurities into the silicon solid raw material and to produce a silicon single crystal with high purity.

  Hereinafter, an example of an embodiment of the present invention will be described in detail below, but matters that are not particularly described are the same as those of a solid raw material supply apparatus in a silicon single crystal manufacturing apparatus used by a normal CZ method. It is.

  FIG. 1 is a schematic cross-sectional view showing an example of an embodiment of an apparatus for producing a silicon single crystal according to the present invention. FIG. 2 is a schematic cross-sectional view of a portion of the silicon single crystal manufacturing apparatus of FIG.

  1 and 2, 1 is a main chamber, 2 is a pull chamber, 3 is a silicon melt, 4 is a quartz crucible, 5 is a graphite crucible, 6 is a heater, 7 is a heat insulating material, 8 is a heat shield shield, 9 Are the wire, 10 is the main body of the raw material filling container, 11 is the raw material supply part cover, 12 is the apparatus bottom base, 13 is the support shaft of the crucible, 14 is the exhaust port, 15 is the weight base part, 16 is the opening part, 17 is The locking portion, 18 is a raw material filling container, 19 is a raw material supply portion, and 20A and 20B are connection portions.

  The silicon single crystal manufacturing apparatus in FIG. 1 is a so-called CZ furnace, and includes a main chamber 1 and a pull chamber 2 as furnace bodies. The pull chamber 2 has a smaller diameter than the main chamber 1 and is superimposed on the central portion of the main chamber 1. A crucible is disposed in the center of the main chamber 1.

  In FIG. 1, the crucible has a double structure in which a quartz crucible 4 provided on the inner side and a graphite crucible 5 provided on the outer side thereof are combined. These crucibles are supported by a support shaft 13. The support shaft 13 can be driven to move the crucible up and down or to rotate in the circumferential direction.

  The quartz crucible 4 is used for melting a solid material of silicon. The melting of the solid silicon raw material is performed by exhausting air from the exhaust port 14 to evacuate the quartz crucible 4 and then flowing an inert gas such as Ar gas over the quartz crucible 4.

  A heater 6 is disposed outside the graphite crucible 5. On the further outer side of the heater 6, a heat insulating heat insulating material 7 is disposed on the apparatus bottom pedestal 12 along the inner surface of the main chamber 1. Further, an opening is provided on the heat insulating material, and a heat shield shield 8 having a circumferential portion extending horizontally on the upper side and on the lower side is provided on the lower side.

  A wire 9 as a pulling shaft is suspended in the pull chamber 2. The wire 9 is rotated and driven up and down by a driving mechanism (not shown) provided at the uppermost part of the pull chamber 2.

  In FIG. 1, a solid raw material supply device having a raw material filling container 18 and a raw material supply unit cover 11 is provided below the wire 9.

  The raw material filling container 18 is filled with a silicon solid raw material for supplying silicon to the silicon solid raw material melt in the quartz crucible 4. The raw material filling container 18 includes a main body portion 10 and a raw material supply portion 19.

  The main body 10 is formed of stainless steel or the like, and the shape thereof is, for example, a columnar shape. The main body 10 plays a role of holding a silicon solid raw material filled in the raw material filling container 18.

  The raw material supply unit 19 is a part that supplies the silicon solid material held by the main body unit 10 to the quartz crucible 4. The raw material supply unit 19 has a structure that can be opened and closed at the tip in order to enable both the retention and release of the silicon solid raw material.

  The operation of the raw material filling container 18 is as follows. First, when the raw material filling container 18 of FIG. 1 is lowered, the locking portion 17 comes into contact with a small diameter portion provided in the main chamber, and the lowering of the raw material filling container 18 is stopped. When the wire 9 is further lowered, the raw material supply unit 19 is lowered by its own weight, and the tip of the raw material supply unit 19 is opened. As a result, the solid silicon raw material filled in the raw material filling container 18 is discharged from the raw material supply unit 19 to the outside. Thereafter, the silicon solid raw material falls into the quartz crucible 4 via the raw material supply unit cover 11 and is supplied to the silicon melt.

  The raw material supply unit cover 11 is provided on the lower side of the raw material supply unit 19 so as to cover the raw material supply unit 19. The raw material supply unit cover 11 is connected to the raw material filling container 18 by connecting portions 20A and 20B.

  The raw material filling container 18 is generally made of stainless steel and may deteriorate when approached to a silicon melt exceeding 1410 ° C. In the present invention, the raw material filling container 18 is made of silicon melt. Covering the nearby raw material supply unit 19 with the raw material supply unit cover 11 makes it difficult for silicon melt to adhere due to liquid splashing or the like, and suppresses deterioration of the raw material supply unit 19.

  In particular, if the raw material supply unit cover 11 is formed of a member having excellent heat resistance, the raw material supply unit cover can be used for a long time, thereby sufficiently protecting the raw material filling container 18 from the silicon melt. can do. As such a member having excellent heat resistance, molybdenum, tungsten, or carbon can be used. Note that, under high temperature conditions exceeding 1000 ° C., heat is transmitted as light. Therefore, the material of the raw material supply unit cover 11 is preferably a material that reflects light, that is, has a low emissivity. The emissivity is preferably 0.4 or less, and examples of such a material include molybdenum and tungsten.

  An opening 16 is provided on the leading end side (quartz crucible 4 side) of the raw material supply unit cover 11. The solid silicon raw material released from the raw material supply unit 19 falls from the opening 16 to the quartz crucible 4 via the inside of the raw material supply unit cover 11.

  The tip of the raw material supply unit cover 11 is tapered toward the opening 16. As this shape, for example, the frustum portion 15 is desirable. Such a frustum portion 15 has a trapezoidal vertical cross-sectional shape, and specifically includes a frustum, a truncated pyramid, and the like. By including such a frustum 15, the silicon solid material to be released is less diffused to the inner wall surface of the quartz crucible 4 or the heat shield shield 8, and the collision of the silicon solid material with them is suppressed. Can do.

  Furthermore, it is preferable that the center of the opening 16 and the center of the crucible coincide when viewed from above. As a result, since the silicon solid raw material falls near the center of the crucible, the silicon solid raw material is less likely to collide with the inner wall surface of the quartz crucible 4 or the heat shield shield 8, thereby reducing adverse effects on them. can do.

  By using the silicon single crystal manufacturing apparatus described above, the silicon single crystal manufacturing method of the present invention can be performed. The specific method is as already described in detail in the description of the manufacturing apparatus.

  By using this method for producing a silicon single crystal of the present invention, it is possible to prevent impurities from being mixed into the silicon solid raw material and to produce a silicon single crystal with high purity.

  Note that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present invention.

It is a cross-sectional schematic diagram which shows the structure of the silicon single crystal manufacturing apparatus of this invention. It is a cross-sectional schematic diagram which shows the supply apparatus which concerns on this invention.

Explanation of symbols

1: Main chamber 2: Pull chamber 3: Silicon melt 4: Quartz crucible 5: Graphite crucible 6: Heater 7: Thermal insulation 8: Heat shield 9: Wire 10: Body 11: Raw material supply cover 12: Device bottom pedestal 13: crucible support shaft 14: exhaust port 15: weight base 16: opening 17: locking part 18: raw material filling container 19: raw material supply part 20A, 20B: connection part

Claims (4)

A crucible for melting a solid raw material of silicon;
A supply device for supplying the solid raw material,
A raw material filling container including a raw material supply unit for supplying the solid raw material to the crucible;
An apparatus for producing a silicon single crystal, comprising: a supply device that includes a raw material supply portion cover that covers the raw material supply portion and tapers toward an opening provided on the crucible side. The raw material supply unit cover is
2. The apparatus for producing a silicon single crystal according to claim 1, comprising molybdenum, tungsten or silicon carbide. The supply device includes:
The silicon single crystal manufacturing apparatus according to claim 1 or 2, wherein when viewed from above, the center of the opening is arranged so as to coincide with the center of the crucible. A method for producing a silicon single crystal including a supply step of supplying a solid raw material of silicon to a crucible,
The supply step includes
Discharging the silicon raw material filled in the raw material filling container from the raw material supply unit;
A step of dropping the solid raw material into the crucible through a raw material supply part cover that covers the raw material supply part and has an opening tapered toward the crucible.