WO2007148486A1

WO2007148486A1 - SINGLE-CRYSTAL SiC, PROCESS FOR PRODUCING THE SAME, AND APPARATUS FOR PRODUCING SINGLE-CRYSTAL SiC

Info

Publication number: WO2007148486A1
Application number: PCT/JP2007/059911
Authority: WO
Inventors: Masanori Ikari; Toru Kaneniwa; Takao Abe
Original assignee: Shin-Etsu Chemical Co., Ltd.
Priority date: 2006-06-23
Filing date: 2007-05-15
Publication date: 2007-12-27
Also published as: KR20090021144A; JP2008001569A; TW200806828A

Abstract

This invention provides a single-crystal SiC for use as a semiconductor device material or an LED material, and a process for producing the same, and an apparatus for producing a single-crystal SiC. In the single-crystal SiC, defects such as micropipes have been suppressed, and the single-crystal SiC has a high quality, is continuous, and has a large diameter. The process for producing a single-crystal SiC comprises the step of fixing an SiC seed single-crystal wafer onto a susceptor, and the step of externally continuously supplying a raw material for single-crystal SiC production onto the SiC seed single-crystal wafer and growing single-crystal SiC. The process is characterized in that the average temperature gradient of the susceptor, SiC seed single-crystal, and single-crystal SiC having a thickness increased with the growth thereof in the vertical direction (longitudinal direction) of the susceptor is not less than 0.5ºC/mm and not more than 9ºC/mm.

Description

Specification

Single crystal SiC, method for manufacturing the same, and apparatus for manufacturing single crystal SiC

Technical field

TECHNICAL FIELD [0001] The present invention relates to single crystal SiC used as a semiconductor device material or LED material, a manufacturing method thereof, and a single crystal SiC manufacturing apparatus.

Background art

[0002] Single crystal SiC is useful as a material for harsh environment devices and power devices because of its large crystal bond energy, large dielectric breakdown electric field, and high thermal conductivity. In addition, its lattice constant is close to that of GaN, so it is also useful as a substrate material for GaN LED.

[0003] Conventionally, this single crystal SiC is manufactured by using the Rayleigh method in which SiC powder is sublimated in a graphite crucible, and the single crystal SiC is recrystallized on the inner wall of the graphite crucible. An improved Rayleigh method in which the SiC seed single crystal is placed in the part to be recrystallized by optimizing the temperature distribution and epitaxially recrystallized, and the gas source is transported onto the heated SiC seed single crystal by the carrier gas and crystallized. Epitaxial growth with chemical reaction on the surface CVD method, sublimation proximity where SiC powder is epitaxially recrystallized on SiC seed single crystal in a state where SiC powder and SiC seed single crystal are in close proximity in a graphite crucible There are laws.

[0004] By the way, at present, each of these single crystal SiC manufacturing methods is considered to have problems. In the Rayleigh method, single crystal SiC with good crystallinity can be produced, but crystals grow on the basis of spontaneous nucleation, so shape control and crystal surface control are difficult, and large-diameter wafers are difficult to control. There is a problem that can not be obtained.

With the improved Rayleigh method, a large-diameter single crystal SiC ingot of about several hundred mZh can be obtained, but since the crystal grows in a spiral shape, the crystal penetrates many crystals called micropipes. There is a problem that minute holes are generated. Although the CVD method can produce high-quality single crystal SiC with high purity and low defect density, it grows epitaxially using a dilute gas source, so the growth rate is slow at around several tens of μmZh. There is a problem that single crystal SiC ingots cannot be obtained. With the sublimation proximity method, high-purity SiC epitaxial growth can be achieved with a relatively simple structure, but due to structural limitations, there is a problem that it is impossible to obtain a long single-crystal SiC ingot.

[0005] Recently, ultrafine silicon dioxide particles and ultrafine carbon particles are supplied onto a SiC seed single crystal that has been heated and held with inert carrier gas, and the diacid oxide is reduced with carbon on the SiC seed single crystal. As a result, a method of epitaxially growing single crystal SiC on SiC seed single crystal has been invented (see Patent Document 1). This method describes that high-quality single-crystal SiC that suppresses defects such as micropipes can be obtained at high speed.

[0006] The manufacturing method disclosed in Patent Document 1 is an SiC manufacturing method for abrasives in that solid silicon dioxide ultrafine particles and solid carbon ultrafine particles are used as raw materials for single crystal SiC manufacturing. It is similar to the famous Atchison method. The Atchison method is a method in which single crystal siC is produced with volume shrinkage by heating caustic anhydride and a carbon source to 2,000 ° C or higher and reducing caustic anhydride with carbon. The Atchison method is complex in reaction, and SiC polycrystals of various polymorphs, sizes, and orientations are produced. In contrast, the manufacturing method disclosed in Patent Document 1 supplies a raw material for producing a single crystal SiC composed of ultrafine particles of diacidic silicon and ultrafine particles of carbon onto a heated and maintained SiC seed single crystal. By controlling the orientation and polymorphism of the single crystal SiC produced while volume shrinking, it is expected that the SiC single crystal will be arranged in an epitaxy on the SiC seed single crystal. It is.

However, in practice, in the manufacturing method disclosed in Patent Document 1, it is difficult to control the crystal growth of single-crystal SiC. When solid-phase reaction between 1 mol of solid silicon dioxide ultrafine particles and 3 mol of solid carbon ultrafine particles produces 1 mol of SiC monoxide gas in addition to lmol of SiC by the reaction of formula (1). . This carbon monoxide gas is presumed to be generated on the Si C seed single crystal where the reaction proceeds.

SiO + 3C → SiC + 2CO † (1)

2

Therefore, unless it is removed from the SiC seed single crystal promptly, the SiC seed single crystal and the reaction growth layer are separated from each other by the carbon monoxide gas. As a result, it is thought that the cause is that the crystal alignment information on the surface of the SiC seed single crystal is not transmitted to the reaction growth layer.

[0008] Patent Document 1: Japanese Patent No. 3505597 Disclosure of the invention

Problems to be solved by the invention

[0009] The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a high-quality long, large-diameter single-crystal SiC in which defects such as micropipes are suppressed, and a method for producing the same. To provide a law. Furthermore, the present invention provides a single crystal that can be suitably used in the production method.

The object is to provide a SiC manufacturing equipment.

Means for solving the problem

[0010] The above problems have been solved by the means described in <1>, <4>, and <5> below.

Preferred embodiments are described below together with 2> and 3>.

<1> A method for producing single crystal SiC, in which a SiC seed single crystal wafer is fixed to a susceptor, and a single crystal SiC raw material is continuously supplied from the outside onto the SiC seed single crystal wafer. Including the step of growing crystalline SiC, the average temperature gradient in the axial direction of the susceptor is 0.5 ° CZ mm or more and 9 ° CZmm or less for the susceptor, the SiC seed single crystal, and the single crystal SiC whose thickness increases with growth. A method for producing single-crystal SiC, characterized in that

<2> The method for producing single crystal SiC according to 1>, wherein the raw material for producing single crystal SiC is silica and carbon,

<3> The method for producing single-crystal SiC according to <1> or <2>, wherein the average temperature gradient is 0.5 ° CZmm or more and 3 ° CZmm or less,

<4> <1> to <3> Single crystal SiC produced by the method according to any one of the above, <5> a chamber provided with a crucible, means for heating the crucible, and a SiC seed single crystal wafer in the crucible A susceptor for fixing a single crystal, and means for supplying a raw material for producing single crystal SiC to a SiC seed single crystal, wherein the susceptor has a controllable thermal function. Manufacturing equipment.

The invention's effect

According to the present invention, it is possible to provide a low-cost single crystal SiC having a high growth rate, a manufacturing method thereof, and a single crystal SiC manufacturing apparatus.

The single crystal SiC obtained by the present invention has reduced generation of micropipes, and is high quality. Quality. Furthermore, according to the present invention, it is possible to provide single crystal SiC having a large large diameter.

Brief Description of Drawings

FIG. 1 is an example of an apparatus for producing the single crystal SiC of the present invention.

Explanation of symbols

[0013] 1 sealed chamber

2 Sealed crucible

3 High frequency induction heating coil

4 types of single crystal wafer

5 Susceptor

6 Supply pipe

7, 7 'Raw material storage tank

8, 8 'control valve

9 Growth layer

10 Vertical direction of susceptor

A inert carrier gas

BEST MODE FOR CARRYING OUT THE INVENTION

[0014] The method for producing a single crystal SiC according to the present invention includes a step of fixing a SiC seed single crystal wafer to a susceptor, and continuously supplying a raw material for manufacturing the single crystal SiC from the outside onto the SiC seed single crystal wafer.

Including the step of growing SiC, the average temperature gradient in the axial direction of the susceptor of the susceptor, the SiC seed single crystal, and the single crystal SiC whose thickness increases with growth is 0.5 ° CZmm or more 9 ° C

It is characterized by being Zmm or less.

The average temperature gradient is 0.5 ° CZmm or more and 9 ° CZmm or less. Force 0.5 ° CZmm or more 3

It is preferable that it is below CZmm.

The average temperature gradient is set so that the SiC single crystal growth layer has a high temperature and the susceptor side has a low temperature.

[0015] By making the average temperature gradient 0.5 ° CZmm or more and 9 ° CZmm or less, the produced single crystal SiC can be grown epitaxially. This is the result of the bonding of the SiC seed single crystal surface. This is probably because crystal orientation information is transmitted to the growth layer of the SiC single crystal.

More specifically, since the average temperature gradient is increased on the growth layer side, which is lower on the susceptor side,

The temperature of the grown single crystal SiC surface is higher than that of the SiC seed single crystal surface. By setting the temperature gradient in this way, the carbon monoxide gas, which is a reaction product, quickly moves to the surface of the growth single crystal SiC by thermal diffusion and is released into the crucible. That is, the generated carbon monoxide gas does not stay inside the grown single crystal SiC, and the SiC seed single crystal and the reaction growth layer are not separated by the carbon oxide gas. As a result, it is thought that the crystal alignment information on the surface of the SiC seed single crystal is well transmitted to the reaction growth layer.

However, if the temperature gradient is greater than 9 ° CZmm, the supersaturation degree of the SiC seed single crystal surface increases, and polymorphic nuclei unrelated to the crystal arrangement information on the SiC seed single crystal surface are generated, and a single crystal cannot be obtained. . On the other hand, if the temperature gradient is less than 0.5 ° CZmm, the growth rate decreases and conversely etching may occur.

In the present invention, the average temperature gradient can be measured as follows.

The temperature gradient is measured on the susceptor side (low temperature side) and the growth layer side (high temperature side), and this temperature difference is the value obtained by dividing the temperature difference by the distance to the temperature sensor force growth layer surface installed at the heat exchanger of the susceptor. is there. Specifically, a temperature sensor is installed in the part of the susceptor where heat exchange is applied, and the temperature is measured to obtain the temperature on the low temperature side. In addition, the correlation between the temperature of the SiC seed single crystal surface and the temperature of the outer surface of the sealed crucible is measured in advance, and the temperature of the outer surface of the sealed crucible is actually measured with a radiation thermometer, and the calculated temperature is measured as the growth layer. It is regarded as the temperature of the surface, and is the temperature on the high temperature side. The average temperature gradient can also be calculated from these temperatures and the temperature sensor from the distance to the susceptor surface, the thickness of the seed single crystal, and the growth rate of the SiC single crystal.

[0017] Any method can be used to bring the average temperature gradient into the above range, but it is preferable to control the temperature gradient because the susceptor has a controllable thermal function.

Specifically, the temperature on the high temperature side is fixed at the manufacturing temperature of the single crystal SiC, and the temperature gradient adjustment can be performed by adjusting the temperature on the low temperature side (the side where the heat exchange of the susceptor is applied). Examples can be shown. The temperature gradient can be adjusted by adjusting the contact area and heat exchange capacity of the susceptor and heat exchanger and controlling the temperature on the low temperature side. When using the above manufacturing equipment without a temperature gradient, the heat exchanger is stopped and a heat insulating material is inserted between the susceptor and the heat exchanger to control the temperature gradient. It is also possible to use it for other purposes without control.

[0018] Preferably, the raw material for producing the single crystal SiC is silica and carbon.

The type, particle size, particle shape and the like of the silica particles used in the present invention are not particularly limited, and for example, high purity silica obtained by flame hydrolysis can be suitably used.

The type, particle size, particle shape and the like of the carbon particles used in the present invention are not particularly limited, and for example, commercially available high purity carbon black can be suitably used.

[0019] The ratio of the continuous supply amount of the silica particles and the carbon particles is not particularly limited, and a desired composition ratio can be appropriately selected. Two or more kinds of the silica particles and the carbon particles may be mixed and used. In addition, the silica particles and carbon particles may be pretreated or a small amount of other components may be added as necessary.

[0020] The supply of the silica particles and the carbon particles onto the SiC seed single crystal wafer is not particularly limited as long as it is a continuous supply method without interruption, and a known method is also used. Can do. Specifically, the one that can transport the powder continuously like a commercially available powder feeder can be exemplified.

When supplying the raw material for producing the single crystal SiC, it is preferable to have a normetic structure substituted with argon or nitrogen in order to prevent oxygen contamination.

[0021] With regard to the supply conditions of the silica particles and the carbon particles onto the SiC seed single crystal wafer, it is sufficient if the raw materials for producing the single crystal SiC are supplied in a mixed state on the SiC seed single crystal wafer. The raw materials for producing the single crystal SiC may be mixed or supplied separately and mixed on the SiC seed single crystal wafer.

In addition, when doping into single crystal SiC, the above single crystal SiC manufacturing raw material may be mixed as a solid source, or the doping component may be mixed as a gas source in the atmosphere inside the single crystal SiC manufacturing apparatus. You may do it.

[0022] The type, size, and shape of the SiC seed single crystal wafer used in the present invention are not particularly limited, and can be appropriately selected depending on the type, size, and shape of the target single crystal SiC. For example, a SiC single crystal obtained by the modified Raley method, or a SiC seed single crystal pretreated if necessary A crystal wafer can be suitably used.

In the present invention, the configuration of the single crystal SiC manufacturing apparatus used for obtaining single crystal SiC is not particularly limited. In other words, the size, heating method, material, raw material supply method, atmosphere adjustment method, temperature control method, etc. depend on the size, shape and type of the target single crystal SiC, the type and amount of the raw material for manufacturing single crystal SiC, etc. It can be selected as appropriate.

The atmosphere of the apparatus preferably has a sealed structure that is preferably substituted with argon or nitrogen in order to prevent oxygen contamination.

In addition, the single crystal SiC production temperature is not particularly limited, and can be set as appropriate according to the size, shape, and type of the target single crystal SiC, and the type and amount of the raw material for producing single crystal SiC. The preferred production temperature is in the range of 1,600-2,400 ° C., for example the temperature outside the closed crucible. The production apparatus used in the present invention is preferably an apparatus capable of controlling the temperature in the temperature range.

In the present invention, any heating method with no particular limitation can be used as the heating method, and high frequency induction heating and electric resistance heating can be exemplified.

[0024] The material of the susceptor holding the SiC seed single crystal wafer is preferably made of graphite in consideration of the operating temperature range, and a cooling mechanism for generating a heat flow in the axial direction of the susceptor is provided. It is preferable. The cooling method is not particularly limited, but is preferably designed so that a preferable temperature gradient can be selected according to the size, shape, and type of the target single crystal SiC.

In the present invention, the SiC single crystal manufacturing apparatus includes a chamber provided with a crucible, means for heating the crucible, a susceptor for fixing a SiC seed single crystal wafer in the crucible, and a SiC seed single connection. It is particularly preferred that the apparatus is for producing single-crystal SiC, characterized in that it has a means for supplying raw materials for producing single-crystal SiC to the crystal, and the susceptor has a controllable thermal function.

FIG. 1 shows an example of an apparatus for producing the single crystal SiC of the present invention. Here, a high frequency induction heating furnace is used.

A carbon-made sealed crucible 2 (diameter 100 mm, height 150 mm) is placed in a water-cooled sealed chamber 1, and a high-frequency induction heating coil 3 is placed outside the water-cooled sealed chamber 1. It is arranged.

A susceptor 5 for holding the SiC seed single crystal wafer 4 is inserted through the lower portion of the sealed crucible. This susceptor extends to the lower side of the hermetic crucible, and can be rotated about the central axis of the susceptor by a rotation mechanism (not shown).

[0027] Further, a controllable heat function is given to the lower end (not shown) of the susceptor, and a heat flow can be generated in the susceptor axial direction 10. Further, the heat flow rate can be adjusted.

The normal direction of the surface holding the SiC seed single crystal wafer at the upper end of the susceptor can be freely set from approximately parallel to the vertical direction of the susceptor to a maximum 45 ° inclination.

[0028] A supply pipe 6 for supplying raw material particles for producing single crystal SiC is inserted through the upper portion of the sealed crucible. Further, the supply pipe is arranged outside the high-frequency induction heating furnace, and a plurality of raw material storage tanks 7 and 7 'whose supply amount can be adjusted independently, and an inert carrier gas supply source (Fig. Connect to each other! / Speak.

When using premixed raw materials for single crystal SiC production, use one raw material storage tank, and when mixing inside the supply pipe, fill the raw material storage tank with silica and carbon powder independently. . Adjust the supply amount from each storage layer with the control valves 8 and 8 ', and then flow the inert carrier gas A while adjusting the flow rate, so that an appropriate amount of raw material for producing single crystal SiC is put inside the sealed crucible. Can be continuously supplied one by one. Examples of the inert carrier gas include nitrogen gas, helium gas, and argon gas. Nitrogen gas and argon gas are preferable, and argon gas can be more preferably used.

In this way, a single crystal SiC layer (growth layer) 9 having a thickness increased with growth is formed on the SiC seed single crystal wafer 4.

[0029] The high-frequency induction heating furnace can be pressure-controlled by a vacuum exhaust system and a pressure control system (not shown), and includes an inert gas mechanism (not shown).

In the embodiment shown in FIG. 1, the supply pipe is arranged on the top and the susceptor is arranged on the bottom. However, the supply pipe can be arranged upside down as long as the operation of the present invention does not change. It is also possible to arrange them diagonally or horizontally.

Example [0030] Examples of the present invention will be described below.

Single crystal SiC was manufactured under the following conditions using the high frequency induction heating furnace. A SiC seed single crystal wafer was fixed to the upper end of the susceptor. The SiC seed single crystal wafers used here are both approximately 10 mm square amorphous single crystal SiC manufactured by the Rayleigh method and single-crystal SiC with a diameter of 2 cm manufactured by the modified Rayleigh method. In addition, each of the just surface, the inclined surface, the C surface, and the Si surface was prepared and used as a seed single crystal.

Carbon (Mitsubishi Chemical's carbon black MA600) and silica (Aerosil 380 manufactured by Nippon Aerosil Co., Ltd.), which are raw materials for producing single crystal SiC, were filled in the raw material storage tanks independently. Moreover, each supply amount ratio adjusted to silica Z carbon = 1.5-5.0 (weight ratio). At this time, SiC powder can be supplied separately if necessary.

[0031] After the inside of the high frequency induction heating furnace was evacuated, the inside of the high frequency induction heating furnace was replaced with an inert gas (high purity argon or high purity nitrogen). Next, the carbon-made closed crucible was heated by the high-frequency induction heating coil and adjusted so that the surface temperature force i of the SiC seed single crystal wafer was in the range of 600 to 2,390 ° C.

Next, the susceptor on which the SiC seed single crystal wafer was fixed was rotated at a rotation speed of 0 to 20 rpm. In this state, the inert carrier gas (high purity argon or high purity nitrogen) is flowed at a flow rate of 0.5 to: LOlZmin, and the raw material for producing single crystal SiC passes through the inside of the supply pipe. Then, it was continuously supplied onto the surface of the SiC seed single crystal wafer disposed in the lower part of the closed crucible, and single crystal SiC was produced for about 2 hours. As a result, single crystal SiC having a thickness of about lmm was obtained.

At this time, the heat exchange mechanism at the lower end of the susceptor is adjusted, and the average temperature gradient in the susceptor axial direction is 0.2 ° CZmm, 0.5 ° C / mm, 3 ° C / mm, 9 ° C / mm, 10 ° CZmm Under these conditions, single-crystal SiC was manufactured.

[0032] Manufacturing results will be described with reference to Table 1. When the average temperature gradient in the susceptor axis direction was 0.5 ° C / mm or more, the average growth rate was equivalent to 50-500 / ζ πιΖΐι. However, under the condition where the average temperature gradient was 0.2 ° CZmm, the growth rate decreased, and in the worst case, etching was performed in reverse. In addition, under the condition that the average temperature gradient is 10 ° CZmm, the obtained SiC is polycrystalline grown in a columnar shape in a direction substantially normal to the SiC seed single crystal wafer. Epitaxial growth on a single crystal wafer was a powerful force. In addition, when the average temperature gradient was 9 ° C Zmm, the amount of force micro-neuve generated by epitaxy growth increased. On the other hand, when the average temperature gradient is 0.5 ° CZmm and 3 ° CZmm, high-quality single-crystal SiC with few defects such as micropipes where polycrystals are mixed in the manufactured single-crystal SiC is manufactured. I was able to.

[Table 1] Average temperature gradient

0.2 0.5 3 9 10 mm mm j

Growth rate -50 to 100 50 to 500 50 to 500 50 to 500 50 to 500 (IX m / h)

Etching Transparent Transparent Transparent Columnar formation Date f occurs Single crystal Single crystal Single crystal Single crystal Defect Micro / Fif Micro-Micro F Micro F

Claims

The scope of the claims

[1] A method for producing single crystal SiC,

Fixing the SiC seed single crystal wafer to the susceptor; and

Including the step of continuously supplying raw materials for single crystal SiC production from the outside onto a SiC seed single crystal wafer to grow single crystal SiC,

The average temperature gradient in the axial direction of the susceptor of the susceptor, the SiC seed single crystal, and the single crystal SiC that increases in thickness with growth is 0.5 ° CZmm or more and 9 ° CZmm or less.

Single crystal SiC manufacturing method.

2. The method for producing single crystal SiC according to claim 1, wherein the raw materials for producing single crystal SiC are silica and carbon.

[3] The method for producing single-crystal SiC according to claim 1 or 2, wherein the average temperature gradient is not less than 0.5 ° CZmm and not more than 3 ° CZmm.

[4] A single-crystal SiC produced by the method according to any one of claims 1 to 3.

[5] a chamber provided with a crucible and means for heating the crucible,

A susceptor for fixing a SiC seed single crystal wafer in the crucible; and

It has means to supply raw material for single crystal SiC production to SiC seed single crystal,

The susceptor has a controllable heat function.

Single crystal SiC manufacturing equipment.