Classifications

• • C—CHEMISTRY; METALLURGY
  • C30—CRYSTAL GROWTH
  • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
  • C30B15/00—Single-crystal growth by pulling from a melt, e.g. Czochralski method
  • C30B15/10—Crucibles or containers for supporting the melt
  • C30B15/12—Double crucible methods
• • C—CHEMISTRY; METALLURGY
  • C30—CRYSTAL GROWTH
  • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
  • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
  • C30B29/02—Elements
  • C30B29/06—Silicon

Definitions

• the present invention relates to an apparatus for manufacturing large-diameter silicon single crystals according to the Czochralski method. More particularly, the invention relates to a silicon single crystal manufacturing apparatus including a rotation-type quartz crucible containing molten silicon, an electric resistance heater for heating the quartz crucible from the side thereof, a quartz partition member arranged to divide the molten silicon into a single crystal growing section and a material melting section within the quartz crucible and having small holes for permitting the passage of the molten silicon therethrough, and starting material feed means for continuously feeding starting material silicon to the material melting section.
• CZ method which is known as a method of manufacturing large-diameter silicon single crystals
• the amount of molten silicon in a crucible is decreased as a silicon single crystal is grown.
• the dopant concentration is increased and the oxygen concentration is decreased in the silicon single crystal.
• the properties of the silicon single crystal are varied in the direction of its growth. Since the quality required for silicon single crystals has been made severer year after year with increase in the level of integration of LSIs, this problem must be overcome.
• a method is known in which as shown in Fig. 8, the interior of a quartz crucible 1 according to the ordinary CZ method is divided by a cylindrical quartz partition member 22 having small holes 12 for molten silicon 4 and a cylindrical silicon single crystal is grown on the inner side of the partition member 22 while continuously feeding starting material silicon 17 to the outer side of the partition member 22 from starting material feed means 14, and many patents have been disclosed (e.g., Patent Publication No. 40-10184, Laid-Open Patent No. 62- 241889, Laid-Open Patent No. 63-23092, Laid-Open Patent No. 63-319287, Laid-Open Patent No. 64-76992 and laid- Open Patent No.1-96087).
• the crucible side wall portion is higher in temperature than the crucible bottom portion.
• the amount of heat input through the crucible side wall portion is greater than the amount of heat supplied from the crucible bottom portion.
• the convection of the molten silicon within the quartz crucible is predominated by such flows as shown in Fig. 9.
• the proportion of the heat input from the crucible bottom portion becomes greater than the amount of heat applied to the single crystal growing section through the crucible side wall.
• a silicon single crystal manufacturing apparatus including a rotation-type quartz crucible containing molten silicon an electric resistance heater for heating the quartz crucible from the side thereof a quartz partition member arrange to divide the molten silicon into a single crystal growing section and a material melting section within the quartz crucible and having small holes for permitting passage of the molten silicon therethrough and starting material feed means for continuously feeding starting material silicon to the material melting section, and the apparatus is characterized in that the partition member is in the form of a crucible type, that the outer surface of the bottom of the crucible-type partition member is closely fitted to the bottom of the quartz crucible and that the portion connecting the side of the crucible-type partition member and the bottom surface of the partion member has a radius of curvature in the range from 10mm to 50mm .
• the inventors, etc. have considered that in order to construct a double structure crucible in which the quartz thickness at the bottom of its single crystal growing section is increased as mentioned above, the equivalent effect may be possibly obtained by arranging inside a quartz crucible a crucible-type partition member which is smaller than the bore of the quartz crucible.
• the shape of the ordinary quartz crucible is determined by a bore D, a crucible bottom radius of curvature R- a radius of curvature R ? of the portion connecting the bottom and side portions of the crucible.
• the radius of curvature R_. of the crucible bottom is increased with increase in the bore D of the crucible.
• a space corresponding to the difference between the radiuses of curvature is formed between the quartz crucible inner surface and the crucible-type partition member bottom outer surface.
• a space of about 30mm at the maximum is formed between the bottom of the crucible-type partition member 11 and the quartz crucible inner surface.
• the amount of heat input through the bottom still amo ⁇ nts to a greater proportion in the amount of heat applied to the single crystal growing section.
• the space is formed between the bottom outer surface of the crucible-type partition member 11 and the inner surface of the quartz crucible 1.
• the temperature distribtion of the molten silicon in the material melting section is higher in temperature in "the molten silicon bottom that the remainder so that the high-temperature molten silicon is present in the bottom of the crucible-type partition member and the proportion of the heat input through the bottom is increase.
• the method of constructing the double structure crucible for stably pulling a silicon single crystal is such that the partition member 11 is formed into a crucible type and arranged in such a manner that the bottom outer surface of the crucible-type partition member is closely fitted to the bottom of the quartz crucible and the radius of curvature of the portion connecting the side and the bottom of the crucible-type partition member is from 10 to 50mm.
• the area of the double wall structure formed by the close fitting of the crucible-type partition member to the quartz crucible is about 50% of the total area of the bottom of the crucible-type partiton member.
• the valve of Renfin is greater, the closely fitted area becomes less than one half the total area of the bottom of the crucible-type partition member and the effect of reducing the amount of heat input through the bottom is also decreased.
• the reason for setting the lower limit of R ? to 10mm resides in that it is impossible to industrially produce a smaller one.
• Fig. 1 is a diagram schematically showing a quartz double crucible in an embodiment of the present invention
• Fig. 2 is a sectional view showing a silicon single crystal manufacturing apparatus employing a quartz double crucible such as shown in Fig. 1
• Fig.3 is a graph showing the relation between the radius of curvature of the bottom of the crucible-type partition member and the yield of single crystal growth
• Fig. 4 is a graph showing the relation between the radius of curvature of the portion connecting the side and bottom of the partition member and the yield of single crystal growth
• Fig. 5 is a diagram schematically showing a double structure crucible in which the bottom of a single crystal growing section is increased in thickness Fig.
• FIG. 6 is a diagram, showing schematically the shape of the ordinary quartz crucible
• Fig. 7 is a diagram showing schematically the quartz crucible and the crucible-type partition member
• Fig. 8 is a diagram showing schematically a conventional silicon single crystal manufacturing apparatus employing the conventional double structure crucible
• Fig. 9 is a diagram schematically showing the convection of the molten silicon in a case where a single structure crucible is used
• Fig. 10 is a diagram schematicaly showing the convection of the molten silicon in a case where the conventional double structure crucible is used.
• numeral 1 designates a quartz crucible, 2 a graphite crucible, 4 molten silicon, 5 a silicon single crystal, 6 a heater, 8 a chamber, 11 a crucible-type partition member, 12 small holes, 14 starting material feed means, 17 starting material silicon, and 22 a cylindrical partition member.
• Fig. 1 is a sectional view of a quartz double crucible in an embodiment of the present invention.
• numeral 1 designates a quartz crucible, and 11 a crucible-type partition member.
• the crucible-type, partition member 11 is arranged within the quartz crucible 1 to be concentric therewith.
• Numeral 12 designates small holes formed through the crucible-type partition member so that during the growing of a silicon single crystal the molten silicon is supplied from the outer side of the partition member to the inner side of the partition member.
• the quartz crucible 1 comprises a quartz crucible having an inner diameter, 484mm; an outer diameter, 500mm; a bottom inner surface radius of curvature, 500mm; and a crucible height, 200mm; and the crucible-type partition member 11 has an inner diameter, 336mm; an outer diameter, 350mm; a bottom outer surface radius of curvature, 500mm; a radius of curvature of the portion connecting the bottom and side of the crucible-type partition membr, 10mm; and a crucible-type partition member height, 250mm.
• the radius of curvature of the portion connecting the bottom side of the crucible-type partition member is selected 10mm on the ground that it has been impossible to manufacture a quartz crucible of smaller radius of curvature for use as a crucible-type partition member.
• Fig. 2 is a sectional view showing a silicon single crystal manufacturing apparatus employing a quartz double crucible such as shown in Fig. 1.
• Numeral 1 designates a quartz crucible which is set in a graphite crucible 2, and the graphite crucible 2 is supported on a pedestal 3 so as to be vertical movably and rotatable.
• Numeral 4 designates molten silicon contained in the crucible 1 and a silicon single crystal 5 grown into a cylindrical shape is pulled from the molten silicon 4.
• Numeral 6 designates an electric resistance heater surrounding the graphite crucible 2, and 7 a hot-zone heat insulating member surrounding the electric resistance heater 6.
• Numeral 14 designates starting material feed means, and 17 starting material silicon.
• Fig. 3 is a graph showing the relation between the radius of curvature of the bottom of the crucible-type partition member and the yield of single crystal growth.
• the term yield of single crystal growth represents a percentage of the production of a silicon single crystal of over 1mm in length when the growing of a single crystal, i.e. , a silicon single crystal of 6 inches in diameter is effected at a pull rate of about Imm/min.
• the crucible 1 is rotated at 10 rpm and the silicon single crystal 5 is rotated at 20 rpm in opposition to the crucible, thereby growing the silicon single crystal of 6 inches in diameter at a " pull rate of about lmm/min while feeding the starting material silicon 17 into the material melting section from the starting material feed means 14.
• the double crucible is constructed by using the crucible-t ⁇ pe partition member in which the radius of curvature of the portion connecting the bottom and side portion is uniform at about 10mm and the radius of curvature of the bottom portion is different.
• the yield of single crystal growth is decreased with increase in the difference between the radius of curvature of the bottom outer surface of the crucible type partition member and the radius of curvature of the bottom inner surface of the quartz crucible.
• Fig. 4 is a graph showing the results obtained by conducting the similar experiments as Fig. 3 by using a double structure crucible constructed by use of a crucible-type partition member which is closely fitted to a crucible with the radius of curvature of the crucible-type partition member bottom outer surface and the radius of curvature of the outer crucible inner surface having the same value of 500mm and the radiuses of the portions connecting the side and bottom portions of the partion member and the crucible being different from each other.
• the radius of curvature of the portion connecting the bottom and side portions of the crucible-type partition member is selected greater than 50mm, the yield of single crystal growth is decreased.
• the silicon single crystal manufacturing apparatus is constructed as described hereinabove as compared with the amount of heat input through the crucible bottom portion within the single crystal growing section, the amount of heat input through the side portion of the crucible-type partition member is increased so that the resulting heat environment of the molten silicon is equivalent to the heat environment within the ordinary single structure crucible and the amount of heat input through the bottom portion of the crucible within the single crystal growing section is reduced, thus increasing the amount of heat input through the side portion of the crucible-type partition member and thereby ensuring the stable pulling of a long silicon single crystal.
• the silicon single crystal manufacturing apparatus of the present invention is not only applicable to the j manufacture of single crystals of silicon material but also applicable to the manufacture of single crystals of other materials than silicon.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Crystallography & Structural Chemistry (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Crystals, And After-Treatments Of Crystals (AREA)
• Liquid Deposition Of Substances Of Which Semiconductor Devices Are Composed (AREA)

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Citations (2)

• 1990
  • 1990-04-27 JP JP2114519A patent/JPH0412084A/ja active Pending
• 1991
  • 1991-04-24 KR KR1019910701851A patent/KR920702733A/ko not_active Withdrawn
  • 1991-04-24 DE DE19914190942 patent/DE4190942T1/de not_active Withdrawn
  • 1991-04-24 WO PCT/JP1991/000547 patent/WO1991017289A1/en active Application Filing

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