JP2009073696A - SINGLE CRYSTAL SiC AND ITS PRODUCTION METHOD - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing single crystal SiC by which single crystal SiC having unconventionally extremely high quality and large surface area can be stably, continuously and epitaxially grown, and to provide the high quality single crystal SiC obtained by the method. <P>SOLUTION: The method for producing the single crystal SiC includes: an arrangement process for arranging a susceptor 5 to which a SiC seed crystal 4 is fixed and a raw material feeding tube 6 in a crucible 2; and a growth process for growing the single crystal SiC 9 by feeding raw materials for producing the single crystal SiC together with an inert gas A onto the SiC seed crystal 4 in the crucible 2 having a high temperature atmosphere. In the growth process, a process for feeding three raw material components comprising SiC particles, SiO<SB>2</SB>particles and carbon particles as the raw materials for producing the single crystal SiC is included. In the method, the tip end of the raw material feeding tube 6 is processed to have an inner diameter of ≥80% of the crystal diameter of the SiC seed crystal 4. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to single crystal SiC used as a semiconductor device material or LED material, and a method for manufacturing the same.

  Single crystal SiC (silicon carbide) has a large crystal bond energy, a large dielectric breakdown electric field, and a high thermal conductivity, and thus is useful as a material for a device for harsh environments and power devices. Moreover, since the lattice constant is close to the lattice constant of GaN, it is also useful as a substrate material for GaN-LED.

  Conventionally, for the production of single crystal SiC, the Rayleigh method in which SiC powder is sublimated in a graphite crucible and single crystal SiC is recrystallized on the inner wall of the graphite crucible, and the raw material arrangement and temperature distribution are optimized based on this Rayleigh method. An improved Rayleigh method in which a SiC seed single crystal is placed in the recrystallized portion and epitaxially recrystallized, and the gas source is transported onto the SiC seed single crystal heated by the carrier gas and epitaxially grown while chemically reacting on the crystal surface. There is a CVD method, a sublimation proximity method in which SiC powder is epitaxially recrystallized on the SiC seed single crystal in a state where the SiC powder and the SiC seed single crystal are brought close to each other in a closed graphite crucible (Non-patent Document 1). (See Chapter 4).

  By the way, at present, each of these single crystal SiC manufacturing methods is considered to have a problem. Although the Rayleigh method can produce single crystal SiC with good crystallinity, crystal growth is based on spontaneous nucleation, so that shape control and crystal surface control are difficult, and a large-diameter wafer can be obtained. There is no problem. In the improved Rayleigh method, a SiC solid raw material is sublimated and recrystallized, and a single crystal SiC ingot having a large diameter can be obtained at a high speed of about several hundreds μm / h. There is a problem that a large number of micropipes are generated. Furthermore, since it is a batch growth method, there is a limit to continuously producing a long single crystal SiC ingot. The CVD method can produce high-quality single crystal SiC with high purity and low defect density, but because of epitaxial growth with a dilute gas source, the growth rate is as slow as about 10 μm / h, and a long single crystal SiC ingot is formed. There is a problem that it cannot be obtained. In the sublimation proximity method, high-purity SiC epitaxial growth can be realized with a relatively simple structure, but there is a problem that it is impossible to obtain a long single-crystal SiC ingot due to structural restrictions.

Also, recently, by supplying silicon dioxide ultrafine particles and carbon ultrafine particles with an inert carrier gas onto a heated SiC seed single crystal, and reducing the silicon dioxide with carbon on the SiC seed single crystal, the formula ( A method has been reported in which single-crystal SiC is epitaxially grown at a high speed on a SiC seed single crystal by the reaction of 1) (see Patent Document 1).
SiO ₂ + 3C → SiC + 2CO ↑ (1)

Japanese Patent No. 3505597 Edited by Hiroyuki Matsunami, “Semiconductor SiC Technology and Applications”, Nikkan Kogyo Shimbun (published first edition in March 2003)

  In the method for producing single crystal SiC disclosed in the above-mentioned Patent Document 1, since the fine solid material is supplied, the raw material concentration can be kept high, and the occurrence of defects such as micropipes can be suppressed. However, the manufacturing method disclosed in Patent Document 1 is a method in which a SiC single crystal is grown on a SiC seed crystal using a chemical reaction in which silicon dioxide is reduced with carbon on the surface of the SiC seed crystal to obtain single crystal SiC. Therefore, various changes such as volume change and temperature change due to chemical reaction, complicated flow change due to precipitation at multiple locations of raw material that did not contribute to single crystal SiC growth while being supplied, and variations in partial pressure concentration etc. Has unstable elements. Therefore, it is difficult to stably grow high-quality single crystal SiC.

A first object of the present invention is a single-crystal SiC manufacturing method capable of epitaxially continuously growing an extremely stable high-quality single-crystal SiC, which has been a problem, based on the above knowledge, and its The object is to provide the resulting high quality single crystal SiC.
Another object of the present invention is to produce a single-crystal SiC capable of continuously producing a high-quality single-crystal SiC on a larger area SiC seed crystal by utilizing the extremely stable production method. The method and the resulting high quality large area single crystal SiC.

Said subject was solved by the means as described in <1> or <5> below. It is described below together with <2> to <4> which are preferred embodiments.
<1> An arrangement step of arranging a seed crystal for growing a SiC single crystal and a raw material supply pipe for supplying a raw material for producing single crystal SiC in a crucible capable of being heated and maintained at a high temperature, and a high temperature A growth step of growing the SiC single crystal by supplying the raw material for manufacturing the single crystal SiC together with an inert gas through the raw material supply pipe into the crucible in an atmosphere, and the SiC crystal, SiO Including a step of supplying _two raw materials and three raw materials of carbon (C) particles, wherein the inner diameter of the tip of the raw material supply pipe is processed so as to be 80% or more of the crystal diameter of the SiC seed crystal. Method for producing single crystal SiC,
<2> The three raw materials have a molar ratio of SiC particles to SiO ₂ particles in the range of 1: 0.43 to 1: 1.2, and the molar ratio of SiO ₂ particles to carbon (C) particles is 1. : The method for producing single-crystal SiC according to <1>, wherein the single crystal SiC is supplied so as to be in a range of 2 to 1: 3,
<3> The three raw materials have a molar ratio of SiC particles to SiO ₂ particles in the range of 1: 0.54 to 1: 1, and the molar ratio of SiO ₂ particles to carbon (C) particles is 1: The method for producing single-crystal SiC according to <1>, wherein the single-crystal SiC is supplied so as to be within a range of 2 to 1: 3,
<4> The method for producing single crystal SiC according to any one of <1> to <3>, wherein the inert gas is Ar gas,
<5> Single-crystal SiC manufactured by the manufacturing method according to any one of <1> to <4>.

  According to the present invention, a large-area SiC seed single crystal is used to stably reproduce a high-quality large-area single crystal SiC (same size as the seed single crystal) with a smaller defect density than the SiC seed single crystal. It was possible to provide a method for producing single-crystal SiC capable of epitaxial growth with good quality and high-quality single-crystal SiC obtained as a result.

The method for producing single crystal SiC according to the present invention includes a SiC seed crystal for growing a SiC single crystal and a raw material supply pipe for supplying a raw material for producing single crystal SiC in a crucible capable of being heated at high temperature. And a growth step of growing the SiC single crystal by supplying the raw material for producing the single crystal SiC together with an inert gas through the raw material supply pipe into the crucible having a high-temperature atmosphere. Including a step of supplying three raw materials of SiC particles, SiO ₂ particles and carbon (C) particles as a raw material for producing single crystal SiC, the inner diameter of the tip of the raw material supply pipe being 80% or more of the crystal diameter of the SiC seed crystal It is processed so that it becomes.

  According to the present invention, it is caused by various unstable factors such as changes in temperature and carrier gas flow and variations in partial pressure concentration, which have been a problem in the method for producing single crystal SiC disclosed in Patent Document 1. It is possible to solve the low stability reproducibility related to the crystal quality of the manufactured single crystal SiC.

  The excellent reproducibility of the above stable production is something that one skilled in the art cannot expect. It is estimated that the reason why extremely high yield can be achieved is that the manufacturing window with good quality is considerably wide. We are currently studying the mechanism of this stable reproducibility, but we have not yet clarified exactly. However, irrespective of this academic mechanism elucidation, the method for producing a SiC single crystal of the present invention can be specified as described in the above <1>, thereby completing the present invention.

  According to the present invention, since the supply area of the SiC manufacturing raw material is defined so that the SiC manufacturing raw material can be supplied uniformly over the entire surface of the large area SiC seed crystal, the large area SiC seed crystal is used. However, it is presumed that an extremely high quality large-area single-crystal SiC can be manufactured with good reproducibility without deterioration of crystal quality and in-plane unevenness of crystal quality.

The method for producing single crystal SiC according to the present invention includes a SiC seed crystal for growing a SiC single crystal and a raw material supply pipe for supplying a raw material for producing single crystal SiC in a crucible capable of being heated at high temperature. And an arranging step of arranging.
The arrangement process will be described below.

The method for producing single-crystal SiC according to the present invention includes a SiC seed crystal for growing a SiC single crystal in a crucible that can be heated and maintained at a high temperature, and a raw material for supplying a raw material for producing single-crystal SiC. An arrangement step of arranging the supply pipe; In addition, the raw material supply pipe is processed so that the inner diameter of the tip of the raw material supply pipe is 80% or more of the crystal diameter of the SiC seed crystal.
In addition, when raw material powder can be previously stored in the crucible by an appropriate method, the raw material supply pipe may be used as an inert gas supply pipe for supplying only an inert gas.

  The crucible used in the present invention may be any crucible that can raise the temperature to 1,600 to 2,400 ° C., which is a single crystal SiC production temperature, and maintain this temperature. The shape of the crucible is not particularly limited as to its outer shape, and can be appropriately selected according to the size and shape of the target single crystal SiC. The material of the crucible is preferably made of graphite in consideration of the operating temperature range.

  The SiC seed crystal used in the production method of the present invention is preferably a SiC seed single crystal, more preferably a SiC seed single crystal wafer, the type, size and shape are not particularly limited, and the target single crystal It can be appropriately selected depending on the type, size, and shape of SiC. For example, a SiC seed single crystal wafer obtained by pretreating a SiC seed single crystal obtained by an improved Rayleigh method as necessary can be suitably used. The seed crystal may be a just substrate or an off-angle substrate. Examples of the SiC seed single crystal include a just-surface Si surface substrate and a (0001) Si surface substrate having an off angle of several degrees.

In the arrangement step of the manufacturing method according to the present invention, the raw material supply pipe is inserted so as to penetrate the crucible wall and reach the vicinity of the SiC seed crystal in the crucible from the outside of the crucible. This raw material supply pipe flows an inert gas as a carrier, and a mixture of three raw materials of SiC particles, SiO ₂ (silica) particles, and carbon particles, which are raw materials for producing single crystal SiC, is accompanied by an inert gas. It is for supplying to the seed crystal. The inner diameter and cross-sectional shape of the raw material supply pipe are not particularly limited, and can be appropriately selected according to the size and shape of the single crystal SiC to be manufactured. The cross-sectional shape is preferably circular. It is preferable that the other end of the raw material supply pipe is connected to an inert gas storage tank, and a flow rate adjusting valve is provided in the middle of the pipe to adjust the flow rate of the inert gas. The material of the raw material supply pipe in the crucible and in the vicinity of the crucible is preferably made of graphite in consideration of the operating temperature range.

  Processing is performed so that the inner diameter of the tip of the raw material supply pipe is 80% or more of the crystal diameter of the SiC seed crystal. Here, the raw material supply pipe is composed of a pipe portion inserted from the supply source of the inert gas to the inside of the crucible through the raw material storage tank connection portion and a tip portion near the seed crystal. The piping portion is intended to transport the three raw materials, and the inner diameter thereof is 50% or less, preferably 10 to 50%, of the crystal diameter of the SiC seed crystal. The tip portion of the raw material supply pipe is a portion that supplies the three raw material components that have been transported to the SiC seed crystal while accompanying the chemical reaction (1) or sublimation of SiC. The inventors have found that it is useful that the inner diameter of the tip of the raw material supply pipe is processed so as to be 80% or more, preferably 80 to 120% of the crystal diameter of the SiC seed crystal.

FIG. 1 is a conceptual schematic diagram showing an example of an apparatus for producing the single crystal SiC of the present invention. Detailed description will be given later. The crystal diameter d of the SiC seed crystal 4 is also illustrated. The inner diameter r of the tip of the raw material supply pipe is r ≧ 0.8d, preferably 2.0d ≧ r ≧ 0.8d, and more preferably 1.2d ≧ r ≧ 0.8d.
The tip of the raw material supply pipe preferably has a circular end shape, and the tip circular portion is disposed in the vicinity of the SiC seed crystal and is preferably substantially parallel to the seed crystal surface.
A method of processing from a relatively thin pipe portion to a relatively wide tip portion can be arbitrarily selected. FIG. 2 schematically illustrates specific tip shapes (1) to (5).
The material supply pipe is preferably made of graphite in consideration of the operating temperature range for the tip and the piping near the crucible.

The method for producing single-crystal SiC of the present invention includes a single-crystal SiC growth step subsequent to the above-described arrangement step.
In the growth step, single-crystal SiC is produced by supplying three raw materials of SiC particles, silica particles, and carbon particles, which are raw materials for producing single-crystal SiC, together with an inert gas into the crucible in a high-temperature atmosphere. It is a process of growing.

  As the raw material SiC particles used in the production method of the present invention, any crystalline polymorphic SiC crystal can be used. included. Among these, commercially available 3C—SiC can be suitably used. In addition, the SiC particles may be pretreated as necessary. Commercially available 3C—SiC particles are preferable because they are fine particles, have high purity, and are easily available.

  The SiC particles have a particle diameter of preferably 400 nm or less, more preferably 100 nm or less, still more preferably 10 to 100 nm, and particularly preferably 10 to 85 nm. The particle diameter of SiC particles means the weight average particle diameter of primary particles. The particle shape of the SiC particles is not particularly limited. The SiC primary particles are preferably supplied as aggregates.

The kind of SiO ₂ particles, the particle shape, etc. are not particularly limited. The fine particle having a particle size of 100 nm or less is preferable, an ultrafine particle of 10 to 100 nm is more preferable, and an ultrafine particle of 10 to 50 nm is particularly preferable. For example, high-purity silica obtained by a flame hydrolysis method can be suitably used because it satisfies the particle diameter range and has high purity.

  The kind of carbon (C) particle | grains, particle shape, etc. are not specifically limited. The fine particle having a particle size of 100 nm or less is preferable, an ultrafine particle of 10 to 100 nm is more preferable, and an ultrafine particle of 10 to 50 nm is particularly preferable. For example, high-purity acetylene black can be suitably used because it satisfies the above particle diameter range and has high purity.

Any of the above SiC particles, SiO ₂ particles, and carbon (C) particles may be used as a mixture of two or more thereof, or may be mixed and integrated. Further, the SiC particles, the SiO ₂ particles, and the carbon particles may be pretreated as necessary.

The feed ratio of the three raw materials composed of the SiC particles, SiO ₂ particles and carbon (C) particles is such that the molar ratio of SiC particles to SiO ₂ particles is in the range of 1: 0.43 to 1: 1.2. In addition, the molar ratio of SiO ₂ particles to carbon (C) particles is preferably in the range of 1: 2 to 1: 3, and the molar ratio of SiC particles to SiO ₂ particles is 1: 0.54 to 1: 1. More preferably, the molar ratio of SiO ₂ particles to carbon (C) particles is in the range of 1: 2 to 1: 3.

The supply of the supply material (hereinafter also referred to as “raw material 3 component”) composed of SiC particles, SiO ₂ particles and carbon (C) particles, which are the raw materials for producing SiC, is interrupted on the SiC seed single crystal. It is preferable that the method can be continuously supplied, and the specific method is not particularly limited. For example, a commercially available powder feeder that can continuously transport powder can be used. However, the inside of the supply pipe and the single crystal SiC manufacturing apparatus preferably has a hermetic structure replaced with an inert gas such as argon or helium, preferably with argon gas, in order to prevent oxygen contamination.

In addition, when doping is performed in single crystal SiC, if it is p-type, it is easy to mix, for example, Al ₂ O ₃ particles at a high concentration (0.1 to 0.2%) with raw material particles. Moreover, p-type single crystal SiC can be produced even if Al (CH ₃ ) ₃ , B ₂ H _6, etc. are used as a gas source, and n-type single crystal SiC can be easily produced by introducing nitrogen gas into the atmosphere. it can.

The single crystal SiC production temperature is not particularly limited, and can be appropriately set according to the size, shape, type, etc. of the target single crystal SiC, but the preferred production temperature is in the range of 1,600 to 2,400 ° C. The temperature can be measured, for example, as the temperature outside the crucible.
The structure of the single crystal SiC manufacturing apparatus used for the single crystal SiC manufacturing method of the present invention is not particularly limited. That is, the seed crystal size, crucible heating method, crucible material, raw material particle supply method, atmosphere adjustment method, growth pressure, temperature control method, etc. are the target single crystal SiC size, shape, type, SiC particle type, amount, etc. It can be appropriately selected depending on the situation. For example, PID temperature control technology can be used for temperature measurement and temperature control.

  The shape of the susceptor holding the SiC seed single crystal is not particularly limited, and can be appropriately selected according to the size and shape of the target single crystal SiC. The material of the susceptor is preferably made of graphite in consideration of the operating temperature range. The SiC seed crystal can be directly fixed to the end surface of the susceptor with a carbon adhesive.

When holding the SiC seed crystal on the susceptor, a holding method in which no stress is applied to the SiC seed crystal is preferable. That is, it is preferable that the SiC seed crystal is not fixed directly to the susceptor with a carbon adhesive or the like, but is gently placed on the SiC seed crystal holding means by its own weight. The holding means preferably supports the entire periphery of the SiC seed crystal or a part of the periphery from below in the vertical direction. It is preferable that the SiC seed crystal be simply placed on the holding means without using bonding, sandwiching, fixing with a wedge or the like.
Examples of susceptor holding means that satisfy such conditions include three claw-type holders and a ring-type holder.
Here, the claw-shaped holder has three (or four) claw portions that descend vertically from the periphery of the end surface of the susceptor and are bent substantially perpendicularly to the inside at the tip.
The ring-type holder has a circular (ring) shape with a through hole in the center, has a L-shaped cross section, and supports the periphery of the SiC seed crystal at the horizontal portion of the L-shaped portion. It is a tool.
The material of the holding means connected to the susceptor is preferably made of graphite in consideration of the operating temperature range.

  In addition, the susceptor has a separate independent control structure in which a preferable distance is always maintained by separating the relative distance from the raw material supply pipe for continuously supplying the raw material for producing single crystal SiC as the thickness increases due to the growth of single crystal SiC. It is preferable.

  The shape of the raw material supply tube for continuously supplying the raw material for producing single crystal SiC is not particularly limited, and can be appropriately selected according to the size and shape of the target single crystal SiC. As already mentioned, it is preferable that the size of the SiC seed single crystal to be used is 80% or more of the crystal diameter, so that it falls within the range of 80 to 120%. More preferred.

  The raw material supply direction of the raw material supply pipe (the central axis direction of the tip) and the normal direction of the surface of the SiC seed single crystal can be freely arranged in a range from substantially parallel to the maximum perpendicular direction.

FIG. 1 is a conceptual cross-sectional view showing an example of an apparatus for producing single-crystal SiC of the present invention. Here, a high-frequency induction heating furnace 10 is used.
A carbon-made cylindrical crucible 2 (diameter 130 mm, height 180 mm) is disposed in a water-cooled cylindrical chamber 1, and a high-frequency induction heating coil 3 is disposed outside the water-cooled cylindrical chamber 1.
A susceptor 5 for holding the SiC seed crystal 4 is inserted through the upper portion of the cylindrical crucible 2. The susceptor 5 extends to the inside of the cylindrical crucible, and can be rotated about the central axis of the susceptor by a rotation mechanism (not shown).
Further, a controllable heat exchange mechanism is provided at the upper end (not shown) of the susceptor, and a heat flow can be generated in the vertical direction (longitudinal direction) of the susceptor. The heat flow rate can be adjusted. The SiC seed crystal holding portion can be freely set from approximately parallel to the vertical direction of the susceptor to a maximum inclination of 45 °. A SiC single crystal growth layer 9 is grown on the SiC seed crystal 4.

  In the lower part of the cylindrical crucible 2, a raw material supply pipe 6 for supplying three raw materials for producing single crystal SiC is inserted through. Here, the inner diameter of the tip of the raw material supply pipe is designed to be 80% or more of the crystal diameter of the SiC seed single crystal to be used. The raw material supply pipe 6 extends outside the previous high frequency induction heating furnace 10 and has a plurality of raw material storage tanks 7, 7 whose supply amounts can be adjusted independently by the control valves 8, 8 ', 8' '. ', 7' 'and a supply source (not shown) of an inert carrier gas A whose flow rate can be adjusted. The supplied inert carrier gas is discharged from a duct (not shown) provided in the cylindrical chamber 1.

  FIG. 2 is a conceptual cross-sectional view showing another example of an apparatus that can be used to manufacture the single crystal SiC of the present invention. 2 is different from the apparatus shown in FIG. 1 in that three claw-shaped holders are used as seed crystal holding means for holding the SiC seed crystal 4 by the susceptor 5. Other configurations are the same as those of the apparatus shown in FIG. 1, and the description of the reference numerals is also the same as that of FIG.

  The high-frequency induction heating furnace can be controlled by a vacuum exhaust system and a pressure control system (not shown), and includes an inert gas replacement mechanism (not shown). In the embodiment of FIG. 1 or FIG. 2, a high-frequency induction heating furnace having a configuration in which the normal direction of the supply pipe and the susceptor is substantially parallel is shown, but the supply pipe is used as a susceptor within the range where the operation of the present invention does not change. On the other hand, it can be arranged obliquely or horizontally.

In the following, further description will be given based on examples and comparative examples. First, examples will be described.
Using the high frequency induction heating furnace, single crystal SiC was manufactured under the following conditions.
A description will be given with reference to FIG.
3C-SiC particles (trade name NanoPowder, average particle size 45, 55, 82 nm), silica (SiO ₂ particles) (Aerosil 380 manufactured by Nippon Aerosil Co., Ltd.), carbon (C) particles Denka black powder (acetylene black) manufactured by Denki Kagaku Kogyo Co., Ltd. was filled in the raw material storage tank independently. Each supply ratio was adjusted to be as shown in Table 1.

  An SiC seed single crystal wafer was disposed at the lower end of the susceptor. The SiC seed single crystal wafer used here was a large-area 4-inch single crystal SiC substrate manufactured by an improved Rayleigh method. The SiC seed single crystal was set on the susceptor so that no stress was applied to the seed crystal without going through an adhesion process or the like. The tip has an inner diameter of φ80 mm (80% of the crystal diameter of 4 inch single crystal SiC), φ100 mm (100% of the crystal diameter of 4 inch single crystal SiC), and φ120 mm (greater than the crystal diameter of 4 inch single crystal SiC). Each of the three types of raw material supply pipes was repeated and set in a high frequency induction heating furnace. Each time after that, the inside of the high frequency induction heating furnace was evacuated, and then the inside of the high frequency induction heating furnace was replaced with an inert gas (high purity argon). Next, the carbon cylindrical crucible was heated by the high-frequency induction heating coil, and the surface temperature of the SiC seed single crystal wafer was adjusted to be in the range of 1,600 to 2,400 ° C.

Next, the susceptor on which the SiC seed single crystal wafer was set was rotated at a rotation speed of 0 to 20 rpm. In this state, the inert carrier gas (high purity argon) is adjusted to flow in a range of 0.05 to 10 L / min, and the raw material for producing single crystal SiC (3C-SiC particles, silica (SiO ₂ particles), Carbon (C) particles) were continuously supplied on the surface of the SiC seed single crystal wafer disposed in the upper part of the cylindrical crucible through the raw material supply pipe, thereby producing single crystal SiC. The raw material supply pipe was moved in a direction away from the susceptor at a speed in accordance with the growth rate of the single crystal SiC. In addition, about the conditions (No. 1 to 4) of each Example, manufacture of single crystal SiC was repeated 10 times each using three types of raw material supply pipes. In other words, production was performed 120 times. The production thickness was all about 1 mm.

  Thereafter, the defect density and the in-plane variation of the defect density were measured by visual inspection, reflection X-ray topography, and optical microscope observation of the cross section after molten KOH etching (450 to 550 ° C., 3 to 10 minutes). . Table 2 summarizes the evaluation results of the production of 1 mm thick single crystal SiC on a 4-inch wafer. Here, each measurement result is to display the extent to which each of the batches having the highest defect density in 10 times each of the raw material molar ratios is contained. In addition, the defect density of the SiC seed single crystal wafer is also measured in advance, and compared with the defect density of the single crystal SiC manufactured on the SiC seed single crystal wafer by the single crystal SiC manufacturing method of this patent, the crystal quality is deteriorated. It was judged whether it was equivalent, improved or improved.

  From the above results, in all of the obtained SiC single crystals, no in-plane color unevenness or generation of a minute polycrystalline region was observed over the entire surface.

Furthermore, the mixing ratio of the raw material for producing single crystal SiC is in the range of 1: 0.67 to 1: 1 in terms of the molar ratio of SiC particles to SiO ₂ particles, and 1: in the molar ratio of SiO ₂ particles to carbon (C) particles. When adjusted from 2 to 1: 3, it was confirmed that the crystal quality of the produced single crystal SiC was improved as compared with the SiC seed single crystal.
In addition, the mixing ratio of the raw material for producing single crystal SiC is in the range of 1: 0.43 to 1: 1.2 in terms of the molar ratio of SiC particles to SiO ₂ particles, and in the molar ratio of SiO ₂ particles to carbon (C) particles. Even when adjusted from 1: 2 to 1: 3, it was confirmed that the crystal quality of the manufactured single crystal SiC was equivalent to that of the SiC seed single crystal.

Next, Comparative Example 1 will be described.
Using the high frequency induction heating furnace, single crystal SiC was manufactured under the following conditions.
3C-SiC particles (trade name NanoPowder, average particle size 45, 55, 82 nm), silica (SiO ₂ particles) (Aerosil 380 manufactured by Nippon Aerosil Co., Ltd.), carbon (C) particles Denka black powder (acetylene black) manufactured by Denki Kagaku Kogyo Co., Ltd. was filled in the raw material storage tank independently. Each supply amount ratio was adjusted so as to be as described in Table 1 above.

  An SiC seed single crystal wafer was disposed at the lower end of the susceptor. The SiC seed single crystal wafer used here was a large-area 4-inch single crystal SiC substrate manufactured by an improved Rayleigh method. In addition, the SiC seed single crystal was set on the susceptor so that an excessive stress was not applied without an adhesion process or the like. Processed in advance to an inner diameter of φ60 mm (60% of the crystal diameter of 4 inch single crystal SiC), φ40 mm (40% of the crystal diameter of 4 inch single crystal SiC), and φ20 mm (20% of the crystal diameter of 4 inch single crystal SiC). Each of the three types of raw material supply pipes was repeated and set in a high frequency induction heating furnace. Each time after that, the inside of the high frequency induction heating furnace was evacuated, and then the inside of the high frequency induction heating furnace was replaced with an inert gas (high purity argon). Next, the carbon cylindrical crucible was heated by the high-frequency induction heating coil, and the surface temperature of the SiC seed single crystal wafer was adjusted to be in the range of 1,600 to 2,400 ° C.

Next, the susceptor on which the SiC seed single crystal wafer was set was rotated at a rotation speed of 0 to 20 rpm. In this state, the inert carrier gas (high purity argon) is adjusted to flow in a range of 0.05 to 10 L / min, and the raw material for producing single crystal SiC (3C-SiC particles, silica (SiO ₂ particles), Carbon (C) particles) were continuously supplied on the surface of the SiC seed single crystal wafer disposed in the upper part of the cylindrical crucible through the raw material supply pipe, thereby producing single crystal SiC. The raw material supply pipe was moved in a direction away from the susceptor at a speed in accordance with the growth rate of the single crystal SiC. In addition, about the conditions (No. 1 to 4) of each Example, manufacture of single crystal SiC was repeated 10 times each using three types of raw material supply pipes. In other words, production was performed 120 times. The production thickness was all about 1 mm.

  Thereafter, the defect density and the in-plane variation of the defect density were measured by visual inspection, reflection X-ray topography, and optical microscope observation of the cross section after molten KOH etching (450 to 550 ° C., 3 to 10 minutes). . Table 3 summarizes the evaluation results of the production of 1 mm-thick single crystal SiC on a 4-inch wafer. Here, each measurement result is to display the extent to which each of the batches having the highest defect density in 10 times each of the raw material molar ratios is contained. In addition, the defect density of the SiC seed single crystal wafer is also measured in advance, and compared with the defect density of the single crystal SiC manufactured on the SiC seed single crystal wafer by the single crystal SiC manufacturing method of this patent, the crystal quality is deteriorated. It was judged whether it was equivalent, improved or improved. Table 3 summarizes the evaluation results of 4 inch wafer × 1 mm thick single crystal SiC production.

  From the above results, it was confirmed that in all of the obtained SiC single crystals, in-plane color unevenness and clustering of minute polycrystalline regions were generated particularly in the outer peripheral portion.

Furthermore, the mixing ratio of the raw material for producing single crystal SiC is such that the SiC particles and the SiO ₂ particles have a molar ratio of 1: 0.43 to 1: 1.2, and the molar ratio of the SiO ₂ particles to the carbon (C) particles. In all cases adjusted from 1: 2 to 1: 3, it was confirmed that the crystal quality of the produced single crystal SiC was significantly inferior to that of the SiC seed single crystal.

Further, Comparative Example 2 will be described.
Using the high frequency induction heating furnace, single crystal SiC was manufactured under the following conditions.
3C-SiC particles (trade name NanoPowder, average particle size 45, 55, 82 nm), silica (SiO ₂ particles) (Aerosil 380 manufactured by Nippon Aerosil Co., Ltd.), carbon (C) particles Denka black powder (acetylene black) manufactured by Denki Kagaku Kogyo Co., Ltd. was filled in the raw material storage tank independently. Each supply ratio was adjusted to be as described in Table 4 above.

  An SiC seed single crystal wafer was disposed at the lower end of the susceptor. The SiC seed single crystal wafer used here was a large-area 4-inch single crystal SiC substrate manufactured by an improved Rayleigh method. In addition, the SiC seed single crystal was set on the susceptor so that an excessive stress was not applied without an adhesion process or the like. The inner diameter is previously processed to φ80 mm (80% of the crystal diameter of 4 inch single crystal SiC), φ100 mm (100% of the crystal diameter of 4 inch single crystal SiC), and φ120 mm (greater than the crystal diameter of 4 inch single crystal SiC). The three types of raw material supply pipes were repeatedly set in a high-frequency induction heating furnace. Each time after that, the inside of the high frequency induction heating furnace was evacuated, and then the inside of the high frequency induction heating furnace was replaced with an inert gas (high purity argon). Next, the carbon cylindrical crucible was heated by the high-frequency induction heating coil, and the surface temperature of the SiC seed single crystal wafer was adjusted to be in the range of 1,600 to 2,400 ° C.

Next, the susceptor on which the SiC seed single crystal wafer was set was rotated at a rotation speed of 0 to 20 rpm. In this state, the inert carrier gas (high purity argon) is adjusted to flow in a range of 0.05 to 10 L / min, and the raw material for producing single crystal SiC (3C-SiC particles, silica (SiO ₂ particles), Carbon (C) particles) were continuously supplied on the surface of the SiC seed single crystal wafer disposed in the upper part of the cylindrical crucible through the raw material supply pipe, thereby producing single crystal SiC. The raw material supply pipe was moved in a direction away from the susceptor at a speed in accordance with the growth rate of the single crystal SiC. In addition, about the conditions (No. 5 to 9) of each Example, manufacture of single crystal SiC was repeated 10 times each using three types of raw material supply pipes. In other words, it was manufactured 150 times. The production thickness was all about 1 mm.

  Thereafter, the defect density and the in-plane variation of the defect density were measured by visual inspection, reflection X-ray topography, and optical microscope observation of the cross section after molten KOH etching (450 to 550 ° C., 3 to 10 minutes). It was. Table 5 summarizes the evaluation results of the production of 1 mm thick single crystal SiC on a 4-inch wafer. Here, each measurement result is to display the extent to which each of the batches having the highest defect density in 10 times each of the raw material molar ratios is contained. In addition, the defect density of the SiC seed single crystal wafer is also measured in advance, and compared with the defect density of the single crystal SiC manufactured on the SiC seed single crystal wafer by the single crystal SiC manufacturing method of this patent, the crystal quality is deteriorated. It was judged whether it was equivalent, improved or improved. Table 5 shows the evaluation results of manufacturing a 1 mm thick single crystal SiC of a 4-inch wafer.

From the above results, in all of the obtained SiC single crystals, in-plane color unevenness and generation of minute polycrystalline regions were not observed over the entire surface, but the mixing ratio of raw materials for producing single crystal SiC was in molar ratio. Even if SiO ₂ particles are 0.33 or less (and the molar ratio of SiO ₂ particles to carbon (C) particles is 1: 2 to 1: 3) with respect to SiC particles 1, they are 2.33 or more (and SiO ₂ particles and carbon (C ) Even when the molar ratio of the particles is 1: 2 to 1: 3), the crystal quality of the produced single crystal SiC is inferior to that of the SiC seed single crystal, and the No. 1 that supplied the two raw materials. 5 or No. It was confirmed to be superior to 9.

From the above results, the raw material supply pipe is processed so that the inner diameter is 80% or more of the crystal diameter of the SiC seed crystal, and the mixing ratio of the raw material for producing single crystal SiC is the molar ratio of SiC particles to SiO ₂ particles. When the molar ratio of SiO ₂ particles to carbon (C) particles is adjusted from 1: 2 to 1: 3 in the range of 1: 0.67 to 1: 1, the seeds are formed on a large-area SiC seed single crystal. It was confirmed that it is possible to produce large-area single-crystal SiC having a crystal quality equivalent to or higher than that of crystals. In addition, since the raw material can be continuously supplied from the outside in the manufacturing method of the present invention, it is theoretically possible to manufacture single-crystal SiC having a crystal quality higher than that of the SiC seed single crystal as much as possible.

It is a conceptual sectional view showing an example of an apparatus for manufacturing single crystal SiC of the present invention. It is a conceptual sectional view showing another example of an apparatus for manufacturing single crystal SiC of the present invention. It is typical sectional drawing which shows the specific example of the shape from the piping part of the raw material supply pipe | tube used for this invention to a front-end | tip part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cylindrical chamber 2 Cylindrical crucible 3 High frequency induction heating coil 4 SiC seed crystal 5 Susceptor 6 Raw material supply pipe 7, 7 ', 7''Raw material storage tank 8, 8', 8 '' Control valve 9 Growth layer 10 High frequency induction heating Furnace A Inert carrier gas

Claims (5)

An arrangement step of arranging a SiC seed crystal for growing a SiC single crystal and a raw material supply pipe for supplying a raw material for producing single crystal SiC in a crucible capable of being heated and maintained at a high temperature, and
Including a growth step of growing the SiC single crystal by supplying the raw material for producing the single crystal SiC together with an inert gas through the raw material supply pipe into the crucible in a high temperature atmosphere,
The growth step includes a step of supplying three raw materials of SiC particles, SiO ₂ particles and carbon (C) particles as raw materials for producing single crystal SiC.
A process for producing single-crystal SiC, wherein the inner diameter of the tip of the raw material supply pipe is processed to be 80% or more of the crystal diameter of the SiC seed crystal. The three raw material components have a molar ratio of SiC particles to SiO ₂ particles in the range of 1: 0.43 to 1: 1.2, and the molar ratio of SiO ₂ particles to carbon (C) particles is 1: 2. The method for producing single crystal SiC according to claim 1, wherein the single crystal SiC is supplied so as to fall within a range of 1: 3. The three raw material components are such that the molar ratio of SiC particles to SiO ₂ particles is in the range of 1: 0.54 to 1: 1, and the molar ratio of SiO ₂ particles to carbon (C) particles is from 1: 2 to 1. The method for producing single crystal SiC according to claim 1, wherein the single crystal SiC is supplied so as to fall within a range of 3:   The method for producing single crystal SiC according to any one of claims 1 to 3, wherein the inert gas is Ar gas.   Single crystal SiC manufactured by the manufacturing method according to any one of claims 1 to 4.

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