JP2003089594A - Apparatus for manufacturing semiconductor single crystal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus for producing a semiconductor single crystal in which vaporized substances or reaction products from a melt, or the like, can be discharged to the outside of a furnace without bringing them into contact with a graphite crucible or a heater when the single crystal is pulled by a CZ method and which has an inexpensive structure. SOLUTION: An inner tube 11 close to the outer circumferential face of a heater 6 and an outer tube 12 covering the inner circumferential face of an insulating material 7 are provided. The inner tube 11 and the outer tube 12 are made of carbon or a carbon fiber-reinforced carbon. An annular flange part 11a close to the outer circumferential face of a graphite crucible 3 is provided at the upper end of the inner tube 11. Gaseous Ar introduced from the upper part of a chamber 1 is passed through a gap between the lower end of a radiation screen 10 and a melt 4, ascended along the inner face of a quartz crucible 5, then allowed to flow down through a gap between the inner tube 11 and the outer tube 12 and then discharged to the outside of the furnace. It is possible to retard the conversion of the graphite crucible 3 and the heater 6 into silicon carbide and to markedly prolong the service life of these components because gas such as SiO or the like generated from the melt 4 is not brought into contact with the graphite crucible 3 or the heater 6.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor single crystal manufacturing apparatus. 2. Description of the Related Art A high purity silicon single crystal is mainly used for a substrate of a semiconductor device. One of the methods for producing this silicon single crystal is a Czochralski method (hereinafter referred to as a CZ method). is there. In the CZ method, as shown in FIG. 3 as an example, a quartz crucible 5 installed in a chamber 1 of a semiconductor single crystal manufacturing apparatus is filled with polycrystalline silicon, and silicon is heated by a heater 6 provided around the quartz crucible 5. The polycrystal is heated and melted to form a melt 4 and a seed chuck 1
The seed crystal attached to the substrate 4 is immersed in the melt 4, and the seed chuck 14 is pulled up while rotating the seed chuck 14 and the quartz crucible 5 in the same or opposite directions to grow the silicon single crystal 9. In FIG. 3, reference numeral 3 denotes a graphite crucible for accommodating the quartz crucible 5, and reference numerals 7 and 8 denote heat insulating materials. When the silicon polycrystal filled in the quartz crucible 5 dissolves, a reaction between the melt 4 and the quartz crucible 5 causes Si.
O gas is generated. This SiO gas is used for the quartz crucible 5.
Condensed and adhered to the inner surface of the substrate, the surface of the single crystal 9 being pulled up, the inner wall of the chamber 1 and the like, and when it fell into the melt 4, it adhered to the growing single crystal and generated dislocations, thereby deteriorating the yield. Further, when the heater 6, the graphite crucible 3, and the heat insulating cylinder 7 are heated to a high temperature, vapors of C and CO are generated. When these vapors are mixed in the melt 4, the C concentration of the growing single crystal increases. In order to solve such a problem, the evaporant and the reaction product are discharged outside the furnace using an inert gas such as Ar. The inert gas introduced from the upper part of the semiconductor single crystal manufacturing apparatus flows down along the single crystal 9 and then rises from the surface of the melt along the inner wall of the quartz crucible 5 to form a gap between the graphite crucible 3 and the heater 6. Alternatively, the gas is discharged to the outside of the furnace together with the evaporant and the reaction product through an exhaust pipe (not shown) attached to the chamber 1 by flowing down a gap between the heater 6 and the heat insulating cylinder 7. [0004] The above evaporates and reaction products adhere to the graphite crucible 3, the heater 6, the heat insulating cylinder 7, etc. while being transported outside the furnace together with the inert gas. The flow of the inert gas into the graphite crucible 3 promotes SiC conversion by reaction with SiO. The thickness reduction occurs due to the SiC conversion of the divided surface, and the graphite crucible 3 is deformed. Along with this, the quartz crucible 5 accommodated in the graphite crucible 3 is also deformed and the melt surface position is changed, the temperature distribution of the melt 4 is changed and the growth of the single crystal 9 during pulling is inhibited. . On the other hand, the center portion and the slit portion of the heater 6 are rapidly reduced in thickness due to the SiC. As a result, the temperature distribution of the melt 4 changes, which adversely affects the quality of the single crystal, for example, the oxygen concentration. In order to solve the above-mentioned problem, Japanese Patent Application Laid-Open No.
According to 37492, a single crystal growth apparatus is disclosed in which a gas generated from inside a crucible is sucked and discharged together with an inert gas at a position higher than the crucible. However, in the structure of this single crystal growth apparatus, the SiO gas touches the inner wall of the water-cooled chamber above the crucible.
The probability that the iO gas solidifies, adheres and deposits, and falls into the melt with time increases. Therefore, the pulled single crystal becomes polycrystalline, which leads to a decrease in the single crystal acquisition rate and an increase in cost. Further, since the conventional single crystal manufacturing apparatus has an exhaust port provided in the lower portion or the bottom surface of the chamber, the device needs to be modified, which leads to an increase in cost. Japanese Patent Application Laid-Open No. 2-14898 discloses a single crystal manufacturing apparatus characterized in that a space in a chamber is separated into a space including a heater and a space including a crucible, and a shielding wall is provided at the boundary. Have been. The problems with this device are that the thermal barrier is reduced due to the provision of a shielding wall between the heater and the crucible, the service life of the heater is extended but the crucible is not extended, and the conventional single crystal manufacturing equipment must be modified. The cost must be increased because it must be done. The present invention has been made in view of the above-mentioned conventional problems. In pulling up a semiconductor single crystal by the CZ method, an evaporate or a reaction product from a melt is removed from a furnace without touching a graphite crucible or a heater. It is possible to discharge outside,
It is an object of the present invention to provide an inexpensive semiconductor single crystal manufacturing apparatus. In order to achieve the above object, a semiconductor single crystal manufacturing apparatus according to the present invention comprises a crucible for melting a raw material of a semiconductor single crystal and a crucible surrounding the crucible. In a semiconductor single crystal manufacturing apparatus equipped with a heater for heating the raw material and a pulling-up mechanism for pulling up the single crystal by immersing the seed crystal in the melted raw material, an inner cylinder is provided near the outer peripheral surface of the heater, The inner peripheral surface of the heat insulating cylinder arranged so as to surround the heater is covered with the outer cylinder, and the inert gas for purging introduced from the upper part of the semiconductor single crystal manufacturing apparatus is caused to flow down the gap between the inner cylinder and the outer cylinder. Discharge from the semiconductor single crystal manufacturing apparatus. According to the above structure, the inner cylinder close to the outer peripheral surface of the heater of the semiconductor single crystal manufacturing apparatus and the outer cylinder covering the inner peripheral surface of the heat insulating cylinder are provided, and the inert gas for purging is provided. Since the gap between the inner cylinder and the outer cylinder is made to flow down and is discharged outside the apparatus, the evaporant and reaction products from the melt and the like flow down the gap between the inner cylinder and the outer cylinder together with the inert gas. And hardly touch the graphite crucible or heater. Therefore, the use of SiC in the graphite crucible and the heater is avoided, and the useful life can be extended. The inner cylinder and the outer cylinder deteriorate due to contact with the evaporant and the reaction product, and must be replaced at an appropriate cycle. However, the cost is remarkably lower than that of the graphite crucible and the heater. An embodiment of a semiconductor single crystal manufacturing apparatus according to the present invention will be described below with reference to the drawings. FIG.
FIG. 1 is a partial cross-sectional view schematically illustrating a schematic structure of a heat shield type semiconductor single crystal manufacturing apparatus as a first embodiment of the present invention. A graphite crucible 3 is placed at the upper end of a crucible shaft 2 provided at the center of the chamber 1 via a crucible receiver (not shown), and the quartz crucible 5 for storing the melt 4 is the graphite crucible 3.
It is housed inside. The heater 6 and the heat insulating material 7 are provided concentrically around the graphite crucible 3. Single crystal 9 is pulled from the center of quartz crucible 5. A radiation screen 10 is attached to the upper end of the heat insulating material 7. The radiation screen 10 is a heat shield surrounding the single crystal pulling region, and is a conical cylinder whose lower end opening has a diameter smaller than that of the upper end opening. The radiation screen 10 promotes cooling of the single crystal 9 by blocking radiation heat applied to the single crystal 9 from the melt 4, the quartz crucible 5, and the like.
The single crystal pulling speed is increased, and the generation of crystal defects is prevented. In addition, an inert gas introduced from above the chamber 1 is guided around the single crystal 9 to form a gas flow from the center of the quartz crucible 5 to the exhaust hole provided in the chamber 1 through the peripheral edge. Accordingly, a function is provided for removing evaporants and reaction products that inhibit single crystallization, such as SiO generated from the melt 4. In FIG. 1,
Although two types of heat insulating materials 7 and radiation screens 10 having slightly different structures are shown along the left and right sides of the center line, the effect is the same regardless of which one is used. An inner cylinder 11 is installed near the outer peripheral surface of the heater 6 so as to surround the heater 6, and an outer cylinder 12 is mounted on the inner peripheral surface of the heat insulating material 7. The outer cylinder 12 may be in close contact with or close to the inner peripheral surface of the heat insulating cylinder 7. Both the inner cylinder 11 and the outer cylinder 12 are made of carbon or carbon fiber reinforced carbon. At the upper end of the inner cylinder 11, an annular flange portion 11a is provided.
The inner edge of “a” is close to the outer peripheral surface of the graphite crucible 3. When pulling up the single crystal 9, Ar gas introduced from the upper part of the chamber 1 flows down along the outer peripheral surface of the single crystal 9, passes through the gap between the lower end of the radiation screen 10 and the melt 4, It rises along the inner surface of the quartz crucible 5. Then, it flows down the gap between the inner cylinder 11 and the outer cylinder 12 and is discharged out of the chamber 1. Flange part 11 of inner cylinder 11
a Since the inner edge is close to the outer peripheral surface of the graphite crucible 3, A
The r gas hardly flows into the gap between the graphite crucible 3 and the heater 6. Ar gas flows through such a path, so that the evaporant and reaction products generated from the melt 4 and the like are maintained at a high temperature, and the graphite crucible 3 and the heater 6
It can be discharged without touching. Therefore,
SiC of the graphite crucible 3 and the heater 6 is avoided, and the useful life can be greatly extended. Since evaporates and reaction products generated from the melt 4 and the like flow down in the gap between the inner cylinder 11 and the outer cylinder 12 together with Ar gas, the outer peripheral surface of the inner cylinder 11 and the inner peripheral surface of the outer cylinder 12 are formed. Naturally undergoes a chemical reaction and deteriorates.
Therefore, it is necessary to replace it at an appropriate cycle.
The outer cylinder 12 is significantly less expensive than the graphite crucible 3 or the heater 6. Further, in the case of the present embodiment, since no special modification is required for the single crystal manufacturing apparatus, the apparatus cost does not increase. FIG. 2 is a partial sectional view schematically showing a schematic structure of a purge tube type semiconductor single crystal manufacturing apparatus according to a second embodiment of the present invention. Instead of the radiation screen of FIG. 1, a conical or cylindrical purge tube 13 is attached downward at the center of the upper end of the chamber 1,
Ar gas introduced from the upper part of the chamber 1 is guided around the single crystal 9. The other structure including the inner cylinder 11 and the outer cylinder 12 is the same as that of the heat shield type semiconductor single crystal manufacturing apparatus shown in FIG. 1 and the flow path of the Ar gas is also the same, so the description is omitted. I do. In FIG. 2, two types of heat insulating materials 7 having slightly different structures are also shown on the left and right of the center line, but the effect is the same regardless of which one is used. As described above, according to the present invention, C
In a semiconductor single crystal manufacturing apparatus according to the Z method, an inner cylinder close to an outer peripheral surface of a heater and an outer cylinder covering an inner peripheral surface of a heat insulating cylinder are provided, and a purge inert gas is supplied between the inner cylinder and the outer cylinder. Since the gap is made to flow down and discharged outside the furnace, the evaporant and reaction products generated from the melt and the like flow down the gap between the inner cylinder and the outer cylinder together with the inert gas, and pass through the graphite crucible or heater. Hardly touches. Accordingly, the use of SiC in the graphite crucible and the heater is avoided, and the useful life of the graphite crucible and the heater, which had to be replaced relatively early in the past, can be greatly extended. The inner cylinder and the outer cylinder deteriorate due to contact with the evaporant and the reaction product, and must be replaced at an appropriate cycle. However, the cost is remarkably lower than that of the graphite crucible and the heater. Further, in practicing the present invention, there is almost no need to modify the single crystal production apparatus except for the new installation of the inner cylinder and the outer cylinder, and the equipment can be improved at low cost.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial sectional view schematically showing a schematic structure of a heat shield type semiconductor single crystal manufacturing apparatus. FIG. 2 is a partial cross-sectional view schematically showing a schematic structure of a purge tube type semiconductor single crystal manufacturing apparatus. FIG. 3 is a partial sectional view schematically showing a schematic structure of a conventional semiconductor single crystal manufacturing apparatus. [Description of Signs] 3 ... graphite crucible, 5 ... quartz crucible, 6 ... heater, 7 ... heat insulating material, 9 ... single crystal, 11 ... inner cylinder, 12 ... outer cylinder.

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[Procedure amendment] [Submission date] August 15, 2002 (2002.8.1
5) [Procedure amendment 1] [Document name to be amended] Description [Item name to be amended] Claims [Amendment method] Change [Contents of amendment] [Claims] [Claims 1] A crucible for melting the raw material of the semiconductor single crystal;
In a semiconductor single crystal manufacturing apparatus equipped with a heater for heating the raw material in the crucible around the crucible and a pulling mechanism for pulling the single crystal by immersing the seed crystal in the melted raw material, the outer peripheral surface of the heater In addition to providing the located inner cylinder and an outer cylinder arranged on the outer peripheral side with respect to the inner cylinder, the upper end of the inner cylinder is provided with an annular flange portion whose inner edge is close to the outer peripheral surface of the crucible. Producing an inert gas for purging introduced from the top of the semiconductor single crystal manufacturing apparatus through a gap between the inner cylinder and the outer cylinder and discharging the inert gas from the bottom of the semiconductor single crystal manufacturing apparatus. apparatus. 2. A crucible for melting a raw material of a semiconductor single crystal;
In a semiconductor single crystal manufacturing apparatus equipped with a heater for heating the raw material in the crucible around the crucible and a pulling mechanism for pulling the single crystal by immersing the seed crystal in the melted raw material, the outer peripheral surface of the heater A semiconductor single crystal manufacturing apparatus, comprising: an inner cylinder positioned therein; and an outer cylinder disposed on an outer peripheral side with respect to the inner cylinder, and a heat shield surrounding a single crystal pulling region is provided at an upper end of the outer cylinder. An inert gas for purging introduced from the upper part of the semiconductor single crystal manufacturing apparatus, wherein the inert gas for purging flows down the gap between the inner cylinder and the outer cylinder and is discharged from the bottom of the semiconductor single crystal manufacturing apparatus. 3. A crucible for melting a raw material of a semiconductor single crystal;
In a semiconductor single crystal manufacturing apparatus equipped with a heater for heating the raw material in the crucible around the crucible and a pulling mechanism for pulling the single crystal by immersing the seed crystal in the melted raw material, the outer peripheral surface of the heater Provided inner cylinder, and an outer cylinder arranged on the outer peripheral side with respect to the inner cylinder, and a conical or cylindrical purge tube is attached downward at the center of the upper end of the chamber, An inert gas for purging introduced from the top of a semiconductor single crystal manufacturing apparatus is discharged from the bottom of the semiconductor single crystal manufacturing apparatus by flowing down a gap between the inner cylinder and the outer cylinder. . 4. A heat shield surrounding a single crystal pulling region is provided at an upper end of the outer cylinder.
The semiconductor single crystal manufacturing apparatus according to the above. 5. The semiconductor single crystal manufacturing apparatus according to claim 1, wherein a conical or cylindrical purge tube is attached downward at the center of the upper end of the chamber. 6. The semiconductor single crystal manufacturing apparatus according to claim 1, wherein a gas flow is formed from a central portion of the quartz crucible to an exhaust hole provided in the chamber via a peripheral portion. 7. A crucible for melting a raw material of a semiconductor single crystal,
In a semiconductor single crystal manufacturing apparatus equipped with a heater for heating the raw material in the crucible around the crucible and a pulling mechanism for pulling the single crystal by immersing the seed crystal in the melted raw material, the outer peripheral surface of the heater An inner cylinder positioned and an outer cylinder disposed on the outer peripheral side with respect to the inner cylinder are provided, and an inert gas for purging introduced from the upper part of the semiconductor single crystal manufacturing apparatus is moved from the central part of the quartz crucible to the peripheral part. Forming a gas flow reaching one or more exhaust holes provided in the chamber, flowing down a gap between the inner cylinder and the outer cylinder, and discharging the gas from the bottom of the semiconductor single crystal manufacturing apparatus. manufacturing device. 8. A method for producing a semiconductor single crystal, wherein the semiconductor single crystal is pulled by the pulling mechanism of the apparatus for manufacturing a semiconductor single crystal according to claim 1.

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Fumiki Sugita             2612 Shinomiya, Hiratsuka-shi, Kanagawa Komatsu Electronic Gold             Genus Inc. F term (reference) 4G077 AA02 BA04 CF10 EG24 EG25                       HA12

Claims (1)

Claims: 1. A crucible for melting a raw material of a semiconductor single crystal, a heater surrounding the crucible for heating the raw material in the crucible, and a single crystal by dipping a seed crystal in the melted raw material. In a semiconductor single crystal manufacturing apparatus having a pulling mechanism for pulling a crystal, an inner cylinder is provided near an outer peripheral surface of the heater, and an inner peripheral surface of a heat insulating cylinder arranged so as to surround the heater is covered with an outer cylinder. And an inert gas for purging introduced from the top of the semiconductor single crystal manufacturing apparatus is discharged from the bottom of the semiconductor single crystal manufacturing apparatus by flowing down the gap between the inner cylinder and the outer cylinder. manufacturing device.