WO2012063743A1 - n型SiC単結晶の製造方法 - Google Patents
n型SiC単結晶の製造方法 Download PDFInfo
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- WO2012063743A1 WO2012063743A1 PCT/JP2011/075483 JP2011075483W WO2012063743A1 WO 2012063743 A1 WO2012063743 A1 WO 2012063743A1 JP 2011075483 W JP2011075483 W JP 2011075483W WO 2012063743 A1 WO2012063743 A1 WO 2012063743A1
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- crucible
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- single crystal
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- 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
-
- 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
- C30B15/20—Controlling or regulating
-
- 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
- C30B15/30—Mechanisms for rotating or moving either the melt or the crystal
-
- 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
- C30B15/36—Single-crystal growth by pulling from a melt, e.g. Czochralski method characterised by the seed, e.g. its crystallographic orientation
-
- 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
- C30B17/00—Single-crystal growth onto a seed which remains in the melt during growth, e.g. Nacken-Kyropoulos method
-
- 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
- C30B19/00—Liquid-phase epitaxial-layer growth
- C30B19/02—Liquid-phase epitaxial-layer growth using molten solvents, e.g. flux
-
- 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
- C30B29/10—Inorganic compounds or compositions
- C30B29/36—Carbides
Definitions
- SiC Silicon carbide
- SiC is a thermally and chemically stable compound semiconductor.
- SiC has a superior band gap, breakdown voltage, electron saturation rate and thermal conductivity compared to silicon (Si). Therefore, SiC attracts attention as a next-generation power device material.
- SiC is well known as a substance having a crystalline polymorph. Typical crystal polymorphs of SiC are 6H type (hexagonal system having 6 molecules per period), 4H type (hexagonal system having 4 molecules per period), and 3C type (3 per period). A cubic system having molecules).
- the SiC used for the power device material is preferably a single crystal composed of one crystal polymorph, and it is preferable that the SiC single crystal has fewer crystal defects.
- an n-type SiC single crystal having a low electric resistance is applied to a vertical power device such as a SBD (Shotky Barrier Diode) or a MOSFET (Metal-Oxide-Semiconductor Conductor Field Effect Transistor).
- a vertical power device such as a SBD (Shotky Barrier Diode) or a MOSFET (Metal-Oxide-Semiconductor Conductor Field Effect Transistor).
- SBD Silicon Barrier Diode
- MOSFET Metal-Oxide-Semiconductor Conductor Field Effect Transistor
- a method for producing a SiC single crystal by a sublimation method is disclosed in, for example, Japanese Patent Laid-Open No. 05-262599 (Patent Document 1).
- a method for producing a SiC single crystal by a liquid phase growth method is disclosed in, for example, Japanese Patent Application Laid-Open No. 2004-2173 (Patent Document 2).
- the liquid phase growth method is easier to obtain a single crystal with fewer crystal defects than the sublimation method.
- a seeded solution growth method (hereinafter, referred to as a TSSG method), which is one of liquid phase growth methods, an SiC seed crystal composed of an SiC single crystal is immersed in an SiC solution stored in a crucible. Next, the TSSG method grows a SiC single crystal on the SiC seed crystal while pulling up the SiC seed crystal.
- the TSSG method grows a SiC single crystal while pulling up a SiC seed crystal. Therefore, the SiC single crystal can be made long.
- the TSSG method is similar to the Czochralski (CZ) method because the SiC single crystal is grown while pulling up the SiC seed crystal. Therefore, the Si single crystal large diameter technology in the CZ method can be diverted to TSSG. Therefore, the TSSG method has few crystal defects and is suitable for manufacturing a large-diameter and long SiC single crystal ingot.
- An n-type SiC single crystal manufacturing method includes a step of preparing a manufacturing apparatus including a chamber having a region in which a crucible is disposed, heating a region in which the crucible is disposed, and a chamber Evacuating, after evacuating, filling the chamber with a mixed gas containing a rare gas and nitrogen gas, melting the raw material stored in the crucible arranged in the region by heating, A step of generating a SiC solution containing silicon and carbon, and a step of growing an n-type SiC single crystal on the SiC seed crystal by immersing the SiC seed crystal in the SiC solution under a mixed gas atmosphere.
- the method for manufacturing an n-type SiC single crystal according to an embodiment of the present invention can reduce variations in dopant concentration (nitrogen concentration) of the plurality of manufactured n-type SiC single crystal ingots.
- a SiC single crystal is manufactured by the following steps. First, a crucible is placed in the chamber. The chamber is filled with a rare gas. The crucible is heated with a heating device. At this time, the raw material of the SiC solution stored in the crucible melts to become a melt. Furthermore, carbon melts into the melt from the crucible, and an SiC solution is generated.
- the inventors filled a chamber with a mixed gas composed of a rare gas and a nitrogen gas instead of a rare gas, and grown an SiC single crystal to produce an n-type SiC single crystal ingot. Tried. As a result, an n-type SiC single crystal was produced. However, the variation in nitrogen concentration of the plurality of manufactured n-type SiC single crystals was large.
- the present inventors examined the cause of the variation in the nitrogen concentration of the n-type SiC single crystal in the above production method. As a result, the present inventors considered that the nitrogen concentration of the n-type SiC single crystal varies greatly between the n-type SiC single crystals due to the following reasons.
- a nitrogen source exists in the chamber. Specifically, since nitrogen gas is adsorbed in advance to each member in the chamber, each member serves as the nitrogen source. The amount of nitrogen gas released from the nitrogen source in the chamber is so large that it cannot be ignored relative to the amount of nitrogen gas intentionally introduced. Further, every time an n-type SiC single crystal is manufactured (that is, between manufacturing batches), the amount of nitrogen gas released from the nitrogen source in the chamber varies. As a result, the nitrogen concentration of the manufactured n-type SiC single crystal varies greatly for each manufacturing batch, that is, between the SiC single crystals.
- impurity nitrogen gas the nitrogen gas released from the nitrogen source in the chamber by heating is referred to as “impurity nitrogen gas”.
- a method of adjusting the nitrogen gas concentration in the mixed gas in consideration of impurity nitrogen gas is also conceivable.
- the amount of impurity nitrogen gas generated is difficult to quantify. Therefore, the present inventors have previously evacuated the impurity nitrogen gas outside the chamber before growing the n-type SiC single crystal, and then introduced the mixed gas into the chamber to produce the n-type SiC single crystal. It was considered that the variation in nitrogen concentration between n-type SiC single crystal ingots was reduced.
- the present inventors before growing the n-type SiC single crystal, the present inventors heated at least a region where the crucible is disposed in the chamber, and from a member disposed near the region where the crucible is disposed. It was thought that impurity nitrogen gas released by heating should be evacuated.
- the present inventors further examined a preferable heating temperature and degree of vacuum when the impurity nitrogen gas was evacuated.
- a preferable nitrogen concentration in the n-type SiC single crystal is 8.0 ⁇ 10 18 to 3.0 ⁇ 10 19 cm ⁇ 3 .
- the temperature of at least the region where the crucible is arranged is set to 1100 ° C. or higher, and the degree of vacuum in the chamber is set to 1.0 ⁇ 10 ⁇ 1 Pa or lower. It has been found that if the impurity nitrogen gas is exhausted, the variation in the nitrogen concentration of the manufactured n-type SiC single crystal is significantly reduced.
- the method for producing an n-type SiC single crystal according to the present embodiment is based on the above knowledge, and the outline thereof is as follows.
- the region where the crucible is arranged is heated to a temperature higher than the crystal growth temperature of the n-type SiC single crystal.
- the manufacturing method further includes a step of disposing the crucible at a position away from the region in the chamber when the chamber is evacuated, and a step of disposing the crucible in the region after evacuation.
- the raw material in the crucible does not melt in the vacuum exhaust process. Therefore, it is possible to suppress the impurity nitrogen gas generated during the evacuation process from entering the raw material of the crucible.
- the crucible includes a lid member having a through hole.
- the manufacturing apparatus further includes a shaft and a hook member.
- a SiC seed crystal is attached to the lower end of the shaft, and the inside of the chamber can be moved up and down.
- the lower end is disposed in the crucible through the through hole.
- a hook member is arrange
- the step of disposing the crucible at a position away from the region the crucible suspended by the hook member is disposed above the region, and in the step of disposing the crucible in the region, the shaft is lowered and the crucible is disposed in the region.
- a getter that adsorbs nitrogen gas is accommodated in the chamber.
- the SiC single crystal manufacturing apparatus houses a crucible.
- the manufacturing apparatus includes a chamber, an exhaust device that evacuates the chamber, a shaft, and a hook member.
- a SiC seed crystal can be attached to the lower end of the shaft, and the shaft can be raised and lowered.
- a hook member is arrange
- the crucible can be moved up and down by the shaft.
- the crucible includes a lid member having a hole into which the shaft is inserted.
- a hook member is arrange
- the crucible is easily suspended.
- FIG. 1 is a schematic diagram of a SiC single crystal manufacturing apparatus according to the present embodiment.
- the manufacturing apparatus 100 includes a chamber 1, a heat insulating member 2, a heating device 3, an elevating device 4, a rotating device 5, and an exhaust device 6.
- the chamber 1 houses the heat insulating member 2 and the heating device 3. When the n-type SiC single crystal is manufactured, the chamber 1 is water-cooled.
- the chamber 1 includes a main room 11 and a sub room 12. In FIG. 1, the sub room 12 is disposed above the main room 11 and is partitioned by a gate valve 13. In FIG. 1, the gate valve 13 is open.
- the main room 11 has a region where the crucible 7 is arranged.
- the rotating device 5 includes a rotating member 51 and a drive source 52.
- the rotating member 51 includes a rotating table 511 and a shaft 512.
- the drive source 52 is disposed below the chamber 1.
- a lower end portion of the shaft 512 is disposed below the chamber 1, and an upper end of the shaft 512 is disposed in the chamber 1.
- the lower end of the shaft 512 is connected to the drive source 52.
- the turntable 511 is attached to the upper end of the shaft 512.
- the crucible 7 is disposed in the area on the rotary table 511. Specifically, the crucible 7 is disposed on the upper surface of the rotary table 511.
- a plurality of pyrometers (pyrometers) are arranged in an area (hereinafter also referred to as an arrangement area) where the crucible 7 is arranged on the rotary table 511.
- the rotating device 5 rotates the crucible 7. Specifically, the drive source 52 rotates the shaft 512. Therefore, the crucible 7 arranged on the rotary table 511 rotates.
- the crucible 7 includes a casing-like main body 71 and a lid member 72.
- the crucible 7 accommodates the SiC solution 8.
- the SiC solution 8 is an n-type SiC single crystal raw material and contains silicon (Si) and carbon (C).
- the SiC solution 8 may further contain one or more metal elements other than Si and C.
- the SiC solution 8 is generated by melting the raw material of the SiC solution by heating.
- the main body 71 is a casing having an opening at the upper end.
- the main body 71 is made of graphite.
- the lid member 72 is plate-shaped.
- the lid member 72 has a lower surface 74.
- the lid member 72 further has a through hole 73 in the center.
- the lifting device 4 includes a seed shaft 41 and a drive source 42.
- the drive source 42 is disposed above the chamber 1.
- the seed shaft 41 is rod-shaped.
- a lower end portion of the seed shaft 41 is disposed in the chamber 1.
- the upper end portion of the seed shaft 41 is disposed above the chamber 1.
- the upper end portion of the seed shaft 41 is connected to the drive source 42.
- the drive source 42 moves the seed shaft 41 up and down.
- the drive source 42 further rotates the seed shaft 41 around the axis of the seed shaft 41.
- the lower end of the seed shaft 41 is disposed in the crucible 7 through the through hole 73.
- An SiC seed crystal 9 is attached to the lower end of the seed shaft 41.
- the SiC seed crystal 9 has a plate shape and is made of a SiC single crystal.
- the seed shaft 41 is lowered and the SiC seed crystal 9 is immersed in the SiC solution 8.
- the arrangement region is kept at the crystal growth temperature.
- the temperature of the arrangement region is, for example, the surface temperature of the rotary table 511 and is measured by the above-described pyrometer.
- the crystal growth temperature depends on the composition of the SiC solution. A typical crystal growth temperature is 1600 to 2000 ° C.
- the seed shaft 41 further includes a hook member 43.
- the hook member 43 is attached to the seed shaft portion above the lower end of the seed shaft 41.
- the hook member 43 has an annular shape, and the seed shaft 41 is inserted therein.
- the hook member 43 is fixed to the seed shaft 41.
- the hook member 43 is stored in the crucible 7.
- the outer diameter of the hook member 43 is larger than the diameter of the through hole 73.
- the hook member 43 suspends the crucible 7 when the hook member 43 contacts the lower surface 74 of the lid member 72. In this case, the crucible 7 moves up and down together with the seed shaft 41.
- Rotating device 5 rotates crucible 7 when producing a SiC single crystal. Further, the lifting device 4 rotates the seed shaft 41. In short, the crucible 7 and the SiC seed crystal 9 rotate. The seed shaft 41 and the shaft 512 are arranged coaxially. The lifting device 4 further gradually lifts the seed shaft 41 while rotating it. At this time, a SiC single crystal is grown on the surface of the SiC seed crystal.
- the heating device 3 is arranged around the crucible 7.
- the heating device 3 is an annular high-frequency coil, and is arranged coaxially with the seed shaft 41 and the shaft 512.
- the heating device 3 induction heats the arrangement region and the crucible 7, and melts the raw material stored in the crucible 7 to generate the SiC solution 8.
- the heat insulating member 2 has a casing shape, and has a side wall, an upper lid, and a lower lid.
- the side wall of the heat insulating member 2 is disposed between the heating device 3 and the crucible 7.
- the side wall of the heat insulating member 2 is disposed around the crucible 7.
- the upper lid of the heat insulating member 2 is disposed above the lid member 72.
- a through hole 21 for passing the crucible 7 is formed in the upper lid.
- the lower lid of the heat insulating member 2 is disposed below the rotary table 511.
- the lower lid has a through hole through which the shaft 512 passes. In short, the heat insulating member 2 covers the entire crucible 7.
- the heat insulating member 2 includes a well-known heat insulating material.
- the heat insulating material is a fiber-based or non-fiber-based molded heat insulating material. In order to form a SiC single crystal having a diameter of 2 inches or more, it is necessary to maintain high heating efficiency.
- the heat insulating member 2 can maintain high heating efficiency.
- the chamber 1 further includes a gas introduction pipe 110 and gas discharge pipes 111 and 112.
- the gas introduction pipe 110 is connected to the main room 11.
- the gas exhaust pipe 111 connects the main room 11 and the exhaust device 6.
- the gas exhaust pipe 112 connects the sub room 12 and the exhaust device 6.
- Each tube 110 to 112 includes a valve (not shown).
- the exhaust device 6 is, for example, a vacuum pump.
- the exhaust device 6 exhausts the gas in the chamber 1 to the outside through the gas exhaust pipes 111 and 112, and makes the chamber 1 almost vacuum.
- a pressure gauge (not shown) is disposed in the chamber 1. When the exhaust device 6 is operating, the valve of the gas introduction pipe 110 is closed.
- a mixed gas composed of a desired component is introduced into the gas introduction pipe 110.
- the mixed gas contains a predetermined amount of nitrogen gas, and the remainder consists of a rare gas.
- the rare gas is, for example, helium, neon, argon, krypton, xenon, or radon.
- Nitrogen gas becomes an n-type SiC single crystal dopant.
- the nitrogen gas content in the rare gas is determined according to the desired nitrogen concentration of the n-type SiC single crystal.
- the chamber 1 further includes a storage room 14.
- the storage room 14 is arranged next to the main room 11.
- the storage room 14 and the main room 11 are partitioned by an opening / closing door 141. When the open / close door 141 is closed, the storage room 14 is sealed.
- a transport device 142 is disposed in the storage room 14.
- a getter 15 is disposed on the transport device 142.
- the transport device 142 can be moved from the storage room 14 to the main room 11 by a drive source (not shown).
- the getter 15 absorbs nitrogen gas.
- the getter 15 contains one or more selected from the group consisting of titanium (Ti), zirconium (Zr), vanadium (V), and chromium (Cr). All of these elements have a high affinity for nitrogen.
- the method for manufacturing an n-type SiC single crystal according to the present embodiment uses the manufacturing apparatus 100 described above.
- the method for producing an n-type SiC single crystal according to the present embodiment includes an impurity evacuation step, a crucible arrangement step, a mixed gas filling step, an SiC solution generation step, and a single crystal growth step.
- an impurity evacuation step a crucible arrangement step
- a mixed gas filling step a mixed gas filling step
- SiC solution generation step SiC solution generation step
- the chamber 1 is sealed without arranging the crucible 7 in the arrangement area on the rotary table 511. Then, the inside of the chamber 1 is heated by the heating device 3. At this time, the temperature of the arrangement region rises. Further, the chamber 1 is evacuated by the exhaust device 6 while the arrangement region is heated.
- a preferable temperature (also referred to as a heating temperature) of the arrangement region is 1100 ° C. or higher. More specifically, a preferable temperature on the surface of the turntable 511 is 1100 ° C. or higher.
- the heating temperature is 1100 ° C. or higher, most of the nitrogen adhering to each member of the chamber 1 (the heat insulating member 2, the rotating member 51, the seed shaft 41, etc.) is released. Further, the preferable degree of vacuum of the chamber 1 when the arrangement region reaches the heating temperature is 1.0 ⁇ 10 ⁇ 1 Pa or less. In this case, most of the separated impurity nitrogen gas can be exhausted.
- the degree of vacuum in the chamber 1 is 1.0 ⁇ 10 ⁇ 1 Pa or less at a heating temperature of 1100 ° C. or higher, the variation in the nitrogen concentration of the manufactured n-type SiC single crystal is remarkably reduced.
- a preferable degree of vacuum is 5.0 ⁇ 10 ⁇ 2 Pa or less. However, it is not necessary to set it to 1.0 ⁇ 10 ⁇ 2 Pa or less. This is because if the variation in nitrogen concentration can be reduced, the degree of vacuum need not be excessively lowered. Furthermore, excessive reduction in the degree of vacuum lowers production efficiency and increases equipment costs.
- the arrangement region is heated to a temperature higher than the crystal growth temperature.
- the “crystal growth temperature” here means the temperature of the SiC solution in the vicinity of the SiC seed crystal in the single crystal growth step described later. In this case, almost no impurity nitrogen gas is generated in the step of growing the n-type SiC single crystal. This is because the impurity nitrogen gas generated when the arrangement region is maintained at the crystal growth temperature has already been generated in the impurity exhaust process and is exhausted to the outside by the exhaust device 6. Therefore, the variation in the nitrogen concentration of the manufactured SiC single crystal is significantly reduced.
- the preferable degree of vacuum at this time is 1.0 ⁇ 10 ⁇ 1 Pa or less, and more preferably 5.0 ⁇ 10 ⁇ 2 Pa or less.
- the upper limit of the preferred heating temperature is the crystal growth temperature + 100 ° C.
- the preferable holding time of the heating temperature varies depending on the amount of impurity gas adsorbed on the member, but is typically about 1 to 2 hours.
- a getter may be used in the impurity exhaust process.
- the getter 15 is transferred into the main room 11 before the impurity exhausting step is executed. Specifically, the opening / closing door 141 is opened. Then, the transfer device 142 is slid to move from the storage room 14 to the main room 11. The getter 15 is arranged in the main room 11 through the above steps. While the impurity exhaust process is performed, the getter 15 absorbs impurity nitrogen gas. Therefore, the impurity nitrogen gas hardly remains in the chamber 1. After the impurity exhausting process is completed, the getter 15 is stored in the storage room 14. After the getter 15 is stored, the open / close door 141 is closed and the storage room 14 is sealed.
- crucible placement process After carrying out the impurity evacuation step, the crucible 7 is placed on the rotary table 511 (crucible placement step).
- a crucible arrangement process is performed by the following methods, for example.
- the crucible 7 is accommodated in the sub-room 12 as shown in FIG. In FIG. 2, the hook member 43 is in contact with the lower surface 74 of the lid member 72, and the crucible 7 is suspended from the hook member 43. Therefore, the crucible 7 is accommodated in the sub room 12 while being attached to the seed shaft 41. At this time, the gate valve 13 is closed. The SiC seed crystal 9 is attached to the lower end of the seed shaft 41.
- the crucible 7 stores a raw material 80 of the SiC solution 8.
- the raw material 80 may be Si alone or may contain Si and other metal elements.
- the metal element contained in the raw material 80 is, for example, titanium (Ti), manganese (Mn), chromium (Cr), cobalt (Co), vanadium (V), iron (Fe), or the like.
- Preferred elements contained in the raw material 80 are Ti and Mn, and a more preferred element is Ti.
- the subroom 12 is also evacuated by the exhaust device 6.
- the degree of vacuum of the subroom 12 is also set to 1.0 ⁇ 10 ⁇ 1 Pa or less. That is, the degree of vacuum of the sub room 12 is set to be equal to or lower than the degree of vacuum of the main room 11.
- the valves (not shown) of the gas exhaust pipes 111 and 112 are closed. Then, the gate valve 13 is opened and the seed shaft 41 is lowered. At this time, the crucible 7 is lowered.
- the crucible 7 is inserted into the heat insulating member 2 as shown in FIG.
- the seed shaft 41 is further lowered, the crucible 7 is placed on the rotary table 511.
- the hook member 43 is separated from the lower surface of the lid member 72. Therefore, the crucible 7 does not move and only the seed shaft 41 descends.
- the crucible 7 is arranged on the rotary table 511 by the above method.
- positioning the crucible 7 on the turntable 511 is not limited to the said method.
- a transfer device different from the seed shaft 41 may be attached in the chamber 1 and the crucible 7 may be arranged on the rotary table 511 using the transfer device.
- the transfer device is, for example, a robot arm that can hold the crucible 7.
- the chamber 1 is filled with a mixed gas.
- the mixed gas contains nitrogen gas, and the balance consists of one or more rare gases.
- the concentration of nitrogen gas contained in the mixed gas is determined based on the amount of nitrogen that the n-type SiC single crystal should contain. As described above, the preferable nitrogen concentration of the n-type SiC single crystal is 8.0 ⁇ 10 18 to 3.0 ⁇ 10 19 cm ⁇ 3 . In this case, the preferred nitrogen concentration in the mixed gas is 0.02 to 0.10% by volume.
- a preferable pressure in the chamber 1 is atmospheric pressure. This is because if the pressure inside the chamber 1 is set to atmospheric pressure, the subsequent steps can be easily operated. However, the pressure in the chamber 1 may be greater than or equal to atmospheric pressure or less than atmospheric pressure.
- SiC solution generation process and single crystal growth process After filling the mixed gas into the chamber 1, an n-type SiC single crystal is generated (SiC solution generation step and single crystal growth step).
- the SiC solution 8 is generated (SiC solution generation step).
- the raw material 80 in the crucible 7 is heated to the melting point or higher by the heating device 3.
- the SiC solution 8 may further contain other metal elements.
- the carbon in the crucible 7 dissolves in the SiC solution 8, the carbon concentration in the SiC solution 8 approaches the saturation concentration.
- an n-type SiC single crystal is grown (single crystal growth step). Specifically, the seed shaft 41 is further lowered. At this time, the hook member 43 is separated from the lower surface of the lid member 72. Therefore, the crucible 7 does not move and only the seed shaft 41 is lowered. Then, SiC seed crystal 9 is immersed in SiC solution 8.
- At least the arrangement region is held at the crystal growth temperature by the heating device 3. Further, at least a portion in the vicinity of the SiC seed crystal 9 in the SiC solution 8 is supercooled to bring the SiC in the SiC solution 8 into a supersaturated state.
- the vicinity of the SiC seed crystal 9 is simply referred to as “proximal part”.
- a method for cooling at least the vicinity of the SiC solution 8 is as follows.
- the heating device 3 is controlled so that the temperature in the vicinity is lower than the temperature in the other part of the SiC solution 8. Moreover, you may cool the vicinity part with a refrigerant
- the refrigerant is circulated inside the seed shaft 41.
- the refrigerant is, for example, water. If the coolant is circulated in the seed shaft 41, the SiC seed crystal 9 is cooled. Since the vicinity portion is located around the SiC seed crystal 9, if the SiC seed crystal 9 is cooled, the vicinity portion is also cooled. If the vicinity part becomes a supercooled state by the above method, the SiC concentration in the vicinity part of the SiC solution 8 will rise and it will be in a supersaturated state.
- the SiC seed crystal 9 and the SiC solution 8 are rotated while the SiC in the vicinity of the SiC solution 8 is in a supersaturated state.
- the SiC seed crystal 9 rotates.
- the rotating member 51 By rotating the rotating member 51, the crucible 7 rotates.
- the rotation direction of SiC seed crystal 9 may be the reverse direction to the rotation direction of crucible 7 or the same direction. Further, the rotation speed may be constant or may vary.
- the seed shaft 41 gradually rises while rotating. At this time, a SiC single crystal is grown on the surface of the SiC seed crystal 9 immersed in the SiC solution 8 in which SiC is supersaturated.
- nitrogen in the mixed gas in the chamber 1 is taken into the SiC single crystal. Therefore, an n-type SiC single crystal is grown on the surface of SiC seed crystal 9.
- the crystal growth is promoted and the crystal growth becomes uniform.
- the SiC seed crystal 9 is a SiC single crystal having a 4H type crystal structure.
- the grown n-type SiC single crystal also has a 4H type crystal structure.
- the surface of SiC seed crystal 9 (corresponding to the lower surface of SiC seed crystal in FIG. 1) is a (0001) plane or a plane inclined at an angle of 8 ° or less from (0001) plane.
- the method for producing an n-type SiC single crystal As described above, in the method for producing an n-type SiC single crystal according to the present embodiment, nitrogen adhering to various members in the chamber 1 is released by the impurity exhaust process, and the impurity nitrogen gas is exhausted to the outside of the chamber 1. . Thereafter, in the mixed gas filling step, the chamber 1 is filled with a mixed gas having a desired nitrogen concentration. Thereafter, an n-type SiC single crystal is grown. Therefore, variation in the nitrogen concentration of the n-type SiC single crystal due to the impurity nitrogen gas in the chamber 1 can be suppressed.
- the heating temperature of the arrangement region is 1100 ° C. or more and the degree of vacuum is 1.0 ⁇ 10 ⁇ 1 Pa or less, the variation in the nitrogen concentration of the n-type SiC single crystal is remarkable. Becomes smaller. Furthermore, if the heating temperature of the arrangement region is equal to or higher than the crystal growth temperature, the variation in the nitrogen concentration of the n-type SiC single crystal is further significantly reduced.
- the nitrogen concentration in the n-type SiC single crystal can be controlled by adjusting the nitrogen concentration in the mixed gas.
- the crucible 7 is arranged in the subroom 12 away from the rotary table 511 in the impurity exhaust process.
- the impurity evacuation process may be heated while the crucible 7 is placed on the turntable 511.
- the heating temperature is preferably less than the melting point of the raw material of the SiC solution in the crucible 7. This is because if the heating temperature is equal to or higher than the melting point of the raw material, an SiC solution may be generated in the crucible 7 in the impurity exhaust process.
- a preferable heating temperature in this case is 1100 ° C. or higher and lower than 1400 ° C.
- the chamber 1 includes the main room 11 and the sub room 12, and the main room 11 and the sub room 12 are partitioned by the gate valve 13.
- the chamber 1 includes only the main room 11 and does not need to include the sub room 12 and the gate valve 13.
- the crucible 7 is arranged on the upper portion of the chamber 1 while being suspended from the hook member 43. That is, the crucible 7 is disposed away from the region (on the rotary table 511) where the crucible 7 is disposed.
- the temperature of the raw material in the crucible 7 will be less than the temperature on the turntable 511 even if the temperature on the turntable 511 is 1100 ° C. or higher in the impurity exhaust process. Become. Therefore, the SiC solution 8 is difficult to be generated.
- the graphite crucible 7 is used.
- the crucible 7 is not limited to being made of graphite.
- a film made of SiC may be formed on the inner surface of the crucible 7. In this case, SiC in the coating is dissolved in the melt, and a SiC solution 8 is generated.
- the crucible 7 may not contain carbon, and the raw material may contain carbon (graphite or the like).
- the SiC solution 8 may be generated by the following method. Hydrocarbon gas is introduced into the chamber 1 that houses the crucible 7 having the raw material 80.
- the hydrocarbon gas is, for example, methane or propane.
- the solution in the crucible 7 is heated by the heating device 3 in the chamber 1 into which the hydrocarbon gas has been introduced. At this time, carbon is generated by the thermal decomposition of the gas, and the carbon dissolves in the solution. As a result, the SiC solution 8 is manufactured.
- a mixed gas containing a rare gas and nitrogen gas flows into the chamber 1 from the outside.
- a rare gas and a nitrogen gas may separately flow into the chamber 1 to generate a mixed gas in the chamber 1.
- a plurality of n-type SiC single crystals were manufactured by the TSSG method using a manufacturing apparatus having the same configuration as in FIG.
- Test number 1 In the test of test number 1, a SiC single crystal was produced by the following method.
- impurity gas including impurity nitrogen gas
- positioning process was implemented and the crucible was arrange
- the gas which does not contain nitrogen was flowed in in the chamber 1 by the atmospheric gas adjustment process, and the SiC single crystal production
- helium having a purity of 6N (99.9999% by mass) was introduced into the chamber, and the pressure in the chamber was set to atmospheric pressure.
- the crucible of the chamber was heated to 1850 ° C. by the heating device 3 and held for 1 hour.
- the SiC seed crystal was disk-shaped with a diameter of 2 inches.
- the SiC seed crystal was a SiC single crystal having a 4H type crystal structure and was an on-axis crystal.
- the SiC single crystal was grown by immersing the SiC seed crystal in the SiC solution in the crucible for 5 hours. The crystal growth temperature at this time was 1850 ° C. Further, the heating device was controlled so that the temperature of the surrounding solution in which the SiC seed crystal was immersed was about 15 ° C. lower than the temperature of the other part of the solution.
- the part in which the SiC seed crystal was immersed in the solution was in a supercooled state. Further, the seed shaft and the crucible were constantly rotated in opposite directions. The number of rotations was 10 rpm for both the seed shaft and the crucible. After 5 hours, the seed shaft was raised by 20 mm, the produced SiC single crystal was taken out of the SiC solution, and crystal growth was interrupted.
- the seed shaft was lowered and the SiC single crystal was immersed in the SiC solution. And the production
- the crystal growth production conditions (crystal growth temperature, solution temperature around the SiC seed crystal, and rotation speed of the seed shaft and crucible) were the same as those in the undoped material growing step. After 5 hours had passed since the production of the SiC single crystal was resumed, the SiC single crystal was taken out of the SiC solution and crystal growth was completed. Through the above steps, a SiC single crystal that was not doped with nitrogen and a SiC single crystal that was doped with nitrogen were obtained.
- FIG. 4 A cross-sectional photograph of the SiC single crystal obtained by the above method is shown in FIG. 4, and a schematic diagram thereof is shown in FIG. Referring to FIGS. 4 and 5, SiC single crystal 91 not grown with nitrogen is grown on SiC seed crystal 9. Furthermore, a nitrogen-doped SiC single crystal 92 was generated on the SiC single crystal 91.
- the SiC single crystal 91 that is not nitrogen-doped is referred to as an “undoped material”
- the SiC single crystal 92 that is nitrogen-doped is referred to as a “doped material”.
- the reasons for creating the undoped material and the doped material are as follows.
- the nitrogen content of the undoped material corresponds to the nitrogen content (impurity nitrogen gas amount) that is inevitably taken into the SiC single crystal.
- the amount of nitrogen taken into the doping material corresponds to the content of nitrogen intentionally doped. Therefore, the nitrogen content corresponding to the impurity nitrogen gas amount can be quantitatively compared with the intentionally doped nitrogen content.
- Test number 4 In test number 4, compared to test number 1, the degree of vacuum in the impurity exhaust process was different. Specifically, the degree of vacuum was 4.0 ⁇ 10 ⁇ 2 Pa. The other conditions were the same as in test number 1.
- test number 5 a getter containing Ti and Zr was placed in the chamber. Further, the degree of vacuum in the impurity exhaust process was 2.0 ⁇ 10 ⁇ 2 Pa. Furthermore, the mixed gas in the dope material growing step contained 0.06% volume ratio of nitrogen, and the balance was helium gas. The other conditions were the same as in test number 1.
- test number 6 the same getter as test number 5 was stored in the chamber. Further, the heating temperature in the impurity evacuation process was 1900 ° C., and the degree of vacuum was 8.0 ⁇ 10 ⁇ 2 Pa. Heating in the impurity exhaust process was stopped, and the chamber was cooled to room temperature (25 ° C.). The ultimate vacuum at room temperature was 3.0 ⁇ 10 ⁇ 4 Pa. Further, in the dope material growing step, a mixed gas composed of helium gas containing 0.07% by volume of nitrogen gas and having a purity of 99.9999% by mass was used. The other conditions were the same as in test number 1.
- test number 7 the same raw material as test number 2 was used. Then, the same getter as test number 5 was used. The heating temperature in the chamber in the impurity evacuation process was 1900 ° C., and the degree of vacuum was 8.8 ⁇ 10 ⁇ 2 Pa. After stopping heating, it cooled to room temperature (25 degreeC). The ultimate vacuum in the chamber at room temperature was 2.9 ⁇ 10 ⁇ 4 Pa. The same gas as in test number 6 was used as the mixed gas in the dope material growing step. Other conditions were the same as those in Test No. 1.
- Test number 8 In test number 8, the degree of vacuum in the impurity exhaust process was 2.0 ⁇ 10 ⁇ 1 Pa. The other conditions were the same as in test number 1.
- Test number 9 In test number 9, the heating temperature in the impurity exhaust process was 1000 ° C. The degree of vacuum was 9.5 ⁇ 10 ⁇ 2 Pa. Other conditions were the same as those in Test No. 1.
- test number 10 the same raw material as test number 1 was used. In test number 10, the impurity exhaust process was not performed. Specifically, the crucible containing the raw material was housed in the chamber and then evacuated at room temperature. And 99.9999 mass% helium gas was flowed into the chamber until the inside of the chamber became atmospheric pressure. After injecting helium gas, the undoped material growing step and the doped material growing step were performed in the same manner as in Test No. 1. The crystal growth temperature in the undoped material growing step and the doped material growing step was 1850 ° C. In the dope material growing step, a mixed gas composed of helium gas containing 0.02% by volume of nitrogen gas and the balance having a purity of 99.9999% by mass was used.
- the variation value V (%) of the nitrogen concentration of the dope material of each test number was obtained by the following equation (1).
- the “raw material” column in Table 1 shows the raw material of the melt used in each test number.
- “impurity evacuation process” column “implementation” indicates that the impurity evacuation process is performed, and “none” indicates that the impurity evacuation process is not performed. Further, “getter combined use” indicates that the getter is used in the impurity exhaust process.
- the “heating temperature” column indicates the heating temperature (° C.) in the chamber 1 in the impurity exhaust process.
- the “degree of vacuum” column indicates the degree of vacuum (Pa) in the impurity exhaust process.
- the “crystal growth temperature” column indicates the heating temperature (° C.) in the undoped material generation step and the dope material generation step.
- the “used gas” column shows the chemical composition of the atmospheric gas used in the undoped material generation step and the dope material generation step.
- the “nitrogen amount in crystal” column shows the ranges of the five undoped materials and the nitrogen concentration (cm ⁇ 3 ) of the five doped materials obtained for each test number. Further, the “V value” column indicates the variation value V (%) of the nitrogen concentration of the dope obtained by the equation (1).
- “Judgment” column shows the judgment result of whether or not doping control is possible. “Yes” in the “Judgment” column indicates that the V value is 20% or less. “Good” indicates that the V value is 10% or less. “Excellent” indicates that the V value is 1% or less. “Not possible” indicates that the V value exceeds 20%.
- FIG. 6 is a bar graph of the V value of each test number.
- test numbers 1 to 9 an impurity exhaust process was performed. Therefore, the V value was 20% or less.
- the heating temperature in the impurity exhaust process was 1100 ° C. or higher, and the degree of vacuum was 1.0 ⁇ 10 ⁇ 1 Pa or lower. Therefore, the V value was 10% or less.
- the heating temperature was 1900 ° C., which was equal to or higher than the heating temperature (1850 ° C.) when producing the SiC solution. Therefore, the V value was 1% or less.
- the impurity exhaust process was not performed. Therefore, the V value greatly exceeded 20%.
- the V value when the impurity exhaust process was performed was significantly smaller than the V value when the impurity exhaust process was not performed (test number 10).
- FIG. 7 is a bar graph of V values of the same test numbers (test numbers 1, 4 to 6, 8 to 10) for the raw materials in the crucible.
- the V value of test number 10 in which the impurity evacuation process was not performed is the other test numbers (test numbers 1, 4 to 6, It was significantly larger than the V values of 8 and 9).
- test numbers 8 and 9 the heating temperature in the impurity evacuation process was less than 1100 ° C., or the degree of vacuum did not reach 1.0 ⁇ 10 ⁇ 1 Pa.
- the heating temperature in the impurity exhaust process was 1100 ° C.
- test numbers 1 and 4 to 6 were significantly smaller than the V values of test numbers 8 and 9.
- the heating temperature in the impurity exhaust process was lower than the crystal growth temperature.
- the heating temperature in the impurity exhaust process was higher than the crystal temperature. Therefore, the V value of test number 6 was significantly smaller than the V values of test numbers 1, 4 and 5.
- test number 4 Comparing test number 1 and test number 4, in test number 1, the degree of vacuum in the impurity exhaust process did not reach 5.0 ⁇ 10 ⁇ 2 Pa, but in test number 4, the degree of vacuum was 5. 0 ⁇ 10 ⁇ 2 or less. Therefore, the V value of test number 4 was smaller than the V value of test number 1.
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Abstract
Description
本実施の形態によるn型SiC単結晶の製造方法は、TSSG法を利用する。図1は、本実施の形態によるSiC単結晶の製造装置の模式図である。
本実施の形態によるn型SiC単結晶の製造方法は、上記製造装置100を利用する。本実施の形態によるn型SiC単結晶の製造方法は、不純物排気工程と、坩堝配置工程と、混合ガス充填工程と、SiC溶液生成工程と、単結晶育成工程とを備える。以下、各工程の詳細を説明する。
不純物排気工程では、チャンバ1内の不純物窒素ガスを外部に排気する。
不純物排気工程を実施した後、坩堝7を回転テーブル511上に配置する(坩堝配置工程)。坩堝配置工程は、たとえば、以下の方法で行われる。
坩堝配置工程を実行した後、チャンバ1内に混合ガスを充填する。混合ガスは、窒素ガスを含有し、残部は1又は2種以上の希ガスからなる。
混合ガスをチャンバ1に充填した後、n型SiC単結晶を生成する(SiC溶液生成工程及び単結晶育成工程)。
試験番号1の試験では、以下の方法によりSiC単結晶を製造した。
99.9999質量%の純度を有する高純度Si原料と、99.995質量%の純度を有する高純度Ti原料とを、Si:Ti=80:20(モル比)で混合した原料を黒鉛坩堝に収納した。サブルームに坩堝を収納した。次に、不純物排出工程を実施した。具体的には、製造装置内の加熱装置により高周波誘導加熱を行い、チャンバ内を加熱した。さらに、チャンバ内を加熱しながら、チャンバを真空排気した。加熱によりチャンバ内で不純物ガス(不純物窒素ガスを含む)が発生すると、チャンバ内の真空度が悪くなる。そこで、真空度が5×10-1Pa以上となったとき、真空度が5×10-1Pa以下になるまで加熱を停止した。加熱を繰り返しながら、チャンバ内の配置領域(回転テーブル511上の領域)の温度を1100℃とし、真空度を9.0×10-2Paにした。その後、加熱を停止してチャンバ1内の温度を室温(25℃)まで低下させた。このとき、チャンバ1内の真空度は、1×10-3Paであった。
続いて、坩堝配置工程を実施し、坩堝を回転テーブル上に配置した。そして、雰囲気ガス調整工程で窒素を含有しないガスをチャンバ1内に流入し、SiC単結晶生成工程(アンドープ材育成工程)を実行した。具体的には、6N(99.9999質量%)の純度を有するヘリウムをチャンバ内に流入し、チャンバの圧力を大気圧にした。続いて、加熱装置3により、チャンバの坩堝を1850℃に加熱し、1時間保持した。
続いて、ドープ材育成工程を実施した。チャンバ内のヘリウムガスを排出し、代わりに、混合ガスをチャンバ内に流入してチャンバ内の圧力を大気圧にした。混合ガスは、0.05体積%の窒素を含有し、残部は6Nの純度を有するヘリウムガスであった。
試験番号2では、試験番号1と比較して、原料と、不純物排気工程での真空度とが異なっていた。試験番号2では、99.9999質量%の純度を有するSiと、99.9質量%の純度を有するCrとからなる原料を使用した。原料中のSiとCrとの比率は、モル比でSi:Cr=50:50であった。また、不純物排気工程での真空度は9.1×10-2Paであった。その他の条件は、試験番号1と同じであった。
試験番号3では、試験番号1と比較して、原料が異なっていた。試験番号3では、99.9999質量%の純度を有するSiと、99.8質量%の純度を有するTiとからなる原料を使用した。原料中のSiとTiとの比率は、モル比で、Si:Ti=80:20であった。その他の条件は、試験番号1と同じであった。
試験番号4では、試験番号1と比較して、不純物排気工程における真空度が異なっていた。具体的には、真空度が4.0×10-2Paであった。その他の条件は、試験番号1と同じであった。
試験番号5では、チャンバ内にTiとZrとを含有するゲッタを配置した。さらに、不純物排気工程における真空度が2.0×10-2Paであった。さらに、ドープ材育成工程における混合ガスは、0.06%体積率の窒素を含み、残部はヘリウムガスであった。その他の条件は、試験番号1と同じであった。
試験番号6では、試験番号5と同じゲッタをチャンバに収納した。さらに、不純物排気工程における加熱温度は1900℃であり、真空度は8.0×10-2Paであった。不純物排気工程における加熱を停止し、常温(25℃)までチャンバを冷却した。常温での到達真空度は3.0×10-4Paであった。さらに、ドープ材育成工程において、0.07体積%の窒素ガスを含み、残部は純度が99.9999質量%のヘリウムガスからなる混合ガスを利用した。その他の条件は、試験番号1と同じであった。
試験番号7では、試験番号2と同じ原料を用いた。そして、試験番号5と同じゲッタを用いた。不純物排気工程におけるチャンバ内の加熱温度は1900℃であり、真空度は8.8×10-2Paであった。加熱を停止した後、室温(25℃)まで冷却した。室温でのチャンバ内の到達真空度は2.9×10-4Paであった。ドープ材育成工程における混合ガスは、試験番号6と同じものを使用した。その他の条件は試験番号1と同じであった。
試験番号8では、不純物排気工程における真空度は2.0×10-1Paであった。その他の条件は、試験番号1と同じであった。
試験番号9では、不純物排気工程における加熱温度が1000℃であった。また、真空度は9.5×10-2Paであった。その他の条件は試験番号1と同じであった。
試験番号10では、試験番号1と同じ原料を使用した。試験番号10では、不純物排気工程を実施しなかった。具体的には、原料を含む坩堝をチャンバ内に収納した後、室温にて真空排気した。そして、99.9999質量%のヘリウムガスを、チャンバ内が大気圧になるまでチャンバに流入した。ヘリウムガスを流入した後、試験番号1と同様に、アンドープ材育成工程及びドープ材育成工程を実施した。アンドープ材育成工程及びドープ材育成工程での結晶成長温度は1850℃であった。ドープ材育成工程では、0.02体積%の窒素ガスを含み、残部は99.9999質量%の純度を有するヘリウムガスからなる混合ガスを使用した。
試験番号1の試験方法で述べたとおり、各試験番号では、5つのアンドープ材と、5つのドープ材とが製造された。製造された各SiC単結晶(アンドープ材及びドープ材)の窒素濃度を、二次イオン質量分析計(Secondary Ion-Microprobe Mass Spectrometer)で測定した。
V=(5つの窒素濃度の標準偏差/5つの窒素濃度の平均値)×100(%) (1)
[評価結果]
評価結果を表1に示す。
Claims (9)
- 坩堝が配置される領域を有するチャンバを備えた製造装置を準備する工程と、
前記坩堝が配置される領域を加熱し、かつ、前記チャンバを真空排気する工程と、
前記真空排気した後、希ガスと窒素ガスとを含有する混合ガスを前記チャンバ内に充填する工程と、
前記領域に配置された坩堝に収納された原料を加熱により溶融して、シリコンと炭素とを含有するSiC溶液を生成する工程と、
前記混合ガス雰囲気下において、SiC種結晶を前記SiC溶液に浸漬して、前記SiC種結晶上にn型SiC単結晶を育成する工程とを備える、n型SiC単結晶の製造方法。 - 請求項1に記載の製造方法であって、
前記真空排気する工程では、前記領域を1100℃以上に加熱し、かつ、前記チャンバの真空度を1.0×10-1Pa以下にする、製造方法。 - 請求項1又は請求項2に記載の製造方法であって、
前記真空排気する工程では、前記領域を、前記n型SiC単結晶の結晶成長温度以上に加熱する、製造方法。 - 請求項2又は請求項3に記載の製造方法であって、
前記真空排気する工程では、前記チャンバの真空度を5.0×10-2Pa以下にする、製造方法。 - 請求項1~請求項4のいずれか1項に記載の製造方法であって、
前記製造方法はさらに、
前記チャンバを真空排気するとき、前記坩堝を前記チャンバ内の前記領域から離れた位置に配置する工程と、
真空排気後、前記坩堝を前記領域に配置する工程とを備える、製造方法。 - 請求項5に記載の製造方法であって、
前記坩堝は、
貫通孔を有する蓋部材を備え、
前記製造装置はさらに、
下端に前記SiC種結晶が取り付けられ、前記チャンバ内を昇降可能であり、前記下端が前記貫通孔を通って前記坩堝内に配置されるシードシャフトと、
前記シードシャフトの下端から離れたシャフト部分に配置され、前記蓋部材の下面と接触したとき前記坩堝を懸架するフック部材とを備え、
前記坩堝を前記領域から離れた位置に配置する工程では、前記フック部材に懸架された前記坩堝を前記領域の上方に配置し、
前記坩堝を前記領域に配置する工程では、前記シードシャフトを降下して前記坩堝を前記領域に配置する、製造方法。 - 請求項1~請求項6のいずれか1項に記載の製造方法であって、
前記チャンバを真空排気する工程では、窒素ガスを吸着するゲッタを前記チャンバ内に収納する、製造方法。 - 坩堝を収納可能なSiC単結晶の製造装置であって、
チャンバと、
前記チャンバを真空排気する排気装置と、
下端にSiC種結晶を取り付け可能であり、前記チャンバ内を昇降可能なシードシャフトと、
前記シードシャフトの下端から離れたシャフト部分に配置され、前記坩堝を懸架するフック部材とを備える、製造装置。 - 請求項8に記載の製造装置であって、
前記坩堝は、
前記シードシャフトが挿入される穴を有する蓋部材を備え、
前記フック部材は、前記坩堝内に配置され、前記蓋部材の下面と接触することにより前記坩堝を懸架する、製造装置。
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EP11840494.6A EP2639344B1 (en) | 2010-11-09 | 2011-11-04 | METHOD FOR PRODUCING n-TYPE SiC MONOCRYSTAL |
US13/883,350 US9512540B2 (en) | 2010-11-09 | 2011-11-04 | Method for manufacturing N-type SiC single crystal by solution growth using a mixed gas atmosphere |
CN201180054125.7A CN103210127B (zh) | 2010-11-09 | 2011-11-04 | n型SiC单晶的制造方法 |
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EP2857562A1 (en) * | 2012-06-05 | 2015-04-08 | Toyota Jidosha Kabushiki Kaisha | SiC SINGLE-CRYSTAL INGOT, SiC SINGLE CRYSTAL, AND PRODUCTION METHOD FOR SAME |
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US9732436B2 (en) | 2012-06-05 | 2017-08-15 | Toyota Jidosha Kabushiki Kaisha | SiC single-crystal ingot, SiC single crystal, and production method for same |
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EP2639344A4 (en) | 2014-06-25 |
CN103210127B (zh) | 2016-01-13 |
EP2639344B1 (en) | 2016-04-20 |
CN103210127A (zh) | 2013-07-17 |
TWI513866B (zh) | 2015-12-21 |
JP5355533B2 (ja) | 2013-11-27 |
US20130220212A1 (en) | 2013-08-29 |
EP2639344A1 (en) | 2013-09-18 |
US9512540B2 (en) | 2016-12-06 |
JP2012101960A (ja) | 2012-05-31 |
KR101488124B1 (ko) | 2015-01-29 |
KR20130109177A (ko) | 2013-10-07 |
TW201235519A (en) | 2012-09-01 |
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