JP2011035047A - Manufacturing method of single crystal object - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a single crystal object suppressed in the lowering of tightness in a manufacturing device. <P>SOLUTION: The manufacturing method of the single crystal object is that of a single crystal by vapor growth and has a process for supplying nitrogen containing a gas and halogenated hydrogen of a IIIB group element to a seed substrate 3a and reacting the nitrogen containing gas and the halogenated hydrogen of the IIIB group element on the seed substrate 3a, and a process for introducing gas made to flow after the process to an exhaust pipe 14 and heating the gas at a temperature higher than a vaporization temperature of a compound generated by the reaction of the nitrogen containing gas and halogenated hydrogen gas in a heater 16 arranged in the exhaust pipe. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for producing a single crystal by growing the single crystal by a vapor phase growth method.

  Nitride objects such as GaN and AlGaN are used in, for example, light-emitting elements such as light-emitting diodes (LEDs) and semiconductor lasers (LDs), electronic devices such as power devices such as transistors and power FETs (Field Effect Transistors), and the like. , Expansion of use is expected.

  However, group IIIB nitride single crystals such as GaN and AlGaN have a high melting point and a high equilibrium vapor pressure of N (nitrogen), which makes it difficult to produce a bulk single crystal from the liquid phase. is there. Therefore, a thin film made of a group IIIB nitride material is vapor-phase grown on a seed substrate, and the thin film is used for various devices.

  However, when producing a group IIIB nitride single crystal, a hydrogen halide and a nitrogen-containing gas react with each other, and a by-product such as ammonium halide tends to be generated. This ammonium halide has a sublimation property and easily precipitates as a solid at a low temperature, which causes a problem that the exhaust pipe is clogged.

  For example, Patent Document 1 describes a technique in which a heater is provided around a discharge pipe in order to suppress precipitation of ammonium halide.

JP 2001-250820 A

  However, since the required performance differs between the exhaust pipe and the vapor phase growth apparatus, actually, the exhaust pipe and the vapor phase growth apparatus are often different members. For this reason, a connection such as an O-ring is provided between the discharge pipe and the vapor phase growth apparatus to maintain airtightness. However, since the O-ring is made of an elastomer material and is inferior in heat resistance, if a heater is provided around the discharge pipe as in Patent Document 1, the O-ring deteriorates and discharges. There was a problem that the airtightness between the tube and the vapor phase growth apparatus was lowered.

  The present invention has been completed in view of the above-described conventional problems, and an object of the present invention is to provide a method for producing a single crystal in which a decrease in hermeticity in the single crystal production apparatus is suppressed.

  A method for producing a single crystal according to an embodiment of the present invention is a method for producing a single crystal by a vapor phase growth method, supplying a nitrogen-containing gas and a halide of a group IIIB element on a seed substrate, A step 1 of reacting the nitrogen-containing gas and a halide of the group IIIB element on a seed substrate; an exhaust gas flowed after the step 1 is introduced into an exhaust pipe; and the nitrogen-containing gas and the hydrogen halide gas And step 2 of heating the exhaust gas with a heater provided inside the exhaust pipe at a temperature higher than the vaporization temperature of the compound generated by the reaction.

  The heater is rod-shaped and is preferably arranged concentrically with the exhaust pipe.

  It is preferable that the exhaust pipe is composed of two or more pipes, a connection portion of the two pipes is located in the exhaust pipe surrounding the heater in the step 2, and an O-ring is provided in the connection portion.

  Preferably, the method further comprises a step 3 in which the compound heated by the heater in the step 2 is discharged from the exhaust pipe and then cooled to be solidified and collected.

  The vapor phase growth method is preferably a hydride vapor phase growth method.

  The step 1 is preferably performed in a vapor phase growth apparatus, and the step 1 preferably includes a step of flowing an etching gas along the inner wall of the vapor phase growth apparatus.

  The etching gas is preferably a hydrogen halide.

  According to the method for producing a single crystal of the present invention, a nitrogen-containing gas and a group IIIB element halide gas are supplied onto a seed substrate, and the nitrogen-containing gas and a group IIIB element halide gas are supplied onto the seed substrate. The exhaust gas after reacting in step 1 is introduced into the exhaust pipe, and the exhaust gas is introduced into the exhaust pipe at a temperature higher than the vaporization temperature of the compound generated by the reaction between the nitrogen-containing gas and the hydrogen halide gas. Since the heater and the exhaust pipe are separated from each other by heating with the heater provided in the above, even if a connection part such as an O-ring is provided between the exhaust pipe and the vapor phase growth apparatus, the connection part is not Deterioration of the heater due to heat is suppressed. Therefore, since a single crystal can be manufactured while maintaining hermeticity, it is possible to grow a high-quality single crystal with few dislocations and impurities.

(A) is a cross-sectional schematic diagram showing an example of a vapor phase growth apparatus used in the method for producing a single crystal of the present invention. (B) is an enlarged sectional view of the vicinity of the exhaust pipe 14 in the vapor phase growth apparatus shown in (A). It is a cross-sectional schematic diagram which shows an example of the vapor phase growth apparatus used for the manufacturing method of the single crystal of this invention. It is the schematic diagram which looked at the cross section when the reaction heating chamber of the vapor phase growth apparatus S of FIG. 2 was cut | disconnected by the A-A 'line | wire.

  The method for producing a single crystal of the present invention will be described below.

  The present invention is a manufacturing method for producing a single crystal in bulk by growing a single crystal into a seed crystal by a vapor phase growth method.

  As shown in FIG. 1, the seed substrate 3a is placed in the vapor phase growth apparatus S1 while being supported by the support 1. And it heats to 700 degreeC or more with the heaters 4a and 4b, and a single crystal body (especially nitride single crystal body) is made to grow by introduce | transducing carrier gas (not shown) with source gas 5a and 5b. Carrier gas is a laminar flow that prevents turbulent flow, so that reaction products that could not contribute to the growth are transported to the outside of the device, or deposits adhere to the inside of the device. This is a gas flow that is introduced to prevent this. Nitrogen, hydrogen, or a mixed gas thereof can be used as the carrier gas, and the flow rate is several to several tens of times that of the source gases 5a and 5b. Specifically, the flow rate is preferably about 3 to 20 times.

  Examples of the source gas 5a or 5b include a nitrogen-containing gas and a group IIIB halide gas. For example, ammonia is used as the nitrogen-containing gas, for example. Further, for example, gallium chloride is used as the IIIB group element halide gas. In addition, nitrogen, hydrogen, or a mixed gas thereof is used as the carrier gas. When gallium chloride is used as a group IIIB raw material, for example, gallium chloride is generated by causing hydrogen chloride gas to flow through metal gallium at about 800 ° C. for reaction. When reacting gallium chloride and ammonia, it is preferable to heat the support 1 and the seed substrate 3a by setting the temperature of the heaters 4a and 4b to 1000 to 1300 ° C. during single crystal growth.

  In the method for producing a single crystal in the present invention, a heater 15 is provided in the exhaust pipe 14, and ammonium chloride generated from hydrogen chloride gas contained in the gallium chloride gas of the source gas 5a and ammonia of the source gas 5b is used. By-products are prevented from depositing in the exhaust pipe 14. As shown in the enlarged view of the exhaust pipe 14 in FIG. 1B, the exhaust pipe 14 is often one in which two or more pipes are connected. In that case, an O-ring 16 is provided to improve the airtightness. Yes.

  In the present invention, the O-ring 16 and the heater 15 can be separated as much as possible by suitably disposing the rod-shaped heater 15 in the central portion of the exhaust pipe 14 so as to have a coaxial structure with the exhaust pipe 14. . Thereby, the deterioration of the O-ring 16 due to the heat from the heater 15 is suppressed. There is no need to install a heater around the exhaust pipe 14 as has been done so far.

  Note that a small amount of by-products may adhere to the inner wall of the exhaust pipe 14 with only the heater 15 provided at the center of the exhaust pipe 14, but the central portion of the exhaust pipe 14 that is important for exhausting the gas is There is no problem because space is secured. Further, when the by-product adhering to the inner wall adheres to the O-ring, this by-product absorbs and vaporizes heat transmitted from the heater 15 to the O-ring, so that the O-ring is protected from heat. Can do.

  When the heater 15 is cylindrical, the diameter of the heater 15 is preferably 10 to 50, where the inner diameter (diameter) of the exhaust pipe 14 is 100. By being within this range, it is possible to achieve both the securing of the gas flow path in the exhaust pipe 14 and the suppression of heat transfer to the O-ring 16 in the exhaust pipe 14.

  When the by-product is ammonium chloride, the temperature of the heater 15 is set to a temperature higher than the vaporization temperature of ammonium chloride (about 338 ° C.).

  The heater 15 has a structure in which, for example, a wire that generates coiled heat is surrounded by a protective tube made of rod-shaped quartz or the like.

  In FIG. 1, the gas that has passed through the exhaust pipe 14 is cooled in a cooling chamber 17, and byproducts such as ammonium chloride are deposited and collected.

The single crystal obtained by the production method of the present invention as described above has a high quality with a thickness as large as 10 mm or more and a low average dislocation density of 1 × 10 ⁹ cm ⁻² or less.

  Since a plurality of single crystal substrates can be cut out from the bulk seed crystal, a large number of single crystal substrates can be manufactured at one time. The obtained single crystal substrate is excellent in crystallinity and is suitably used as a substrate for growing gallium nitride, for example.

  In addition, the obtained single crystal is processed into a substrate shape by the following method, for example.

  First, the outer periphery of a single crystal grown using a diamond grindstone is ground to a predetermined outer diameter. Next, with a wire saw that cuts the crystal by reciprocating the wire while dripping diamond or SiC abrasive grains into a brass wire with a slurry, the single crystal is fixed to a predetermined thickness. Cut into a wafer shape (for example, 0.6 mm).

  And after rough-polishing both surfaces of a single crystal wafer using a diamond abrasive grain or a SiC abrasive grain, the single crystal substrate is obtained by carrying out mirror polishing of the surface used by a device process using colloidal silica.

  Although the hydride vapor phase growth method has been described as an example of the above vapor phase growth method, a metal organic vapor phase growth method (MOVPE method), a sublimation method, or the like may be used as the vapor phase growth method in the present invention. However, the hydride vapor phase epitaxy method (HVPE method) is preferred because it has a high growth rate, good quality, and is easy to produce a nitride body.

  In the case of a normal HVPE method, the thicker the single crystal is grown, the more by-products are generated as the single crystal is grown. There is a disadvantage that this by-product is mixed into the growing single crystal, or the by-product adheres to the HVPE device and the device fails, resulting in a large thickness and excellent crystallinity. Conventionally, there has been a problem that a single crystal cannot be obtained. Such a problem can be solved by the method for producing a single crystal of the present invention.

  Although FIG. 1 shows a horizontal growth apparatus, the present invention is not limited to this, and a vertical growth apparatus may be used.

  Below, each structure of the vapor phase growth apparatus shown in FIG. 1 is shown.

  Graphite can be used for the support 1, but when corrosive ammonia and hydrogen chloride are used as the source gas, the surface should be coated with one or more selected from the group consisting of SiC, BN and TaC. Is preferred. Examples of the coating method include a CVD method and a sputtering method. Thereby, the corrosion resistance of the support 1 is improved. PBN is preferable among BN. PBN is pyrogenic boron nitride (pyrolytic BN (p-BN)).

  In addition, it is desirable to provide a mechanism (susceptor rotating shaft 1a) for rotating the seed substrate 3a held around the central axis of the support 1 so as to rotate during crystal growth. Thereby, the uniformity of the crystal growing on the seed substrate 3a can be improved. In addition, as rotation speed, it is possible to select from the range of about 2 rpm-50 rpm, for example.

  Here, the seed substrate 3a will be described with an example using a group IIIB nitride single crystal. Specifically, a gallium nitride compound semiconductor such as GaN or AlGaN, AlN, or the like can be used. When the group IIIB nitride single crystal is a GaN single crystal, examples of the seed substrate 3a include sapphire, SiC, GaN single crystal, AlN single crystal, or a mixed crystal of GaN single crystal and AlN single crystal. it can. Among them, GaN single crystals, AlN single crystals, or mixed crystals of GaN single crystals and AlN single crystals are preferably used. The thickness of the seed substrate 3a for growth is about 0.3 to 0.6 mm. The diameter of the seed substrate 3a for growth is 20 mm to 60 mm.

  FIG. 2 shows an example of a vapor phase growth apparatus that can be used in the manufacturing method of the present invention. The vapor phase growth apparatus in FIG. 2 is a vertical type, and an etching gas 10 is flowed in addition to the source gases 5 a and 5 b and the carrier gas 6. FIG. 3 shows a top view of a cross section when the vapor phase growth apparatus S2 shown in FIG. 2 is cut along the line A-A ′. In FIG. 3, the etching gas supply part 12 refers to a gap provided between the first inner cylinder part 9a and the inner cylinder part 9b.

  The etching gas 10 is used to remove excess crystals that have grown in places other than the seed substrate 3a (for example, between the seed substrate 3a and the outer cylinder portion 9b in FIG. 2). As the etching gas 10, a gas capable of etching a single crystal to be grown is selected. For example, when the single crystal is a group IIIB nitride single crystal, examples of the etching gas 10 include hydrogen halides such as hydrogen chloride, hydrogen boride, hydrogen bromide, and hydrogen fluoride. In particular, when the single crystal is GaN, HCl is preferable because it has the best etching performance.

  Thus, as shown in FIG. 2, when the step of flowing an etching gas is included, the etching gas hydrogen gas is added to the hydrogen halide contained in the raw material gas 5b, so that the mixed gas of the etching gas and the raw material gas is used. The concentration of hydrogen halide in the exhaust gas 11 increases. If it does so, it reacts with the source gas 5a in exhaust gas, and a lot of by-products are produced | generated. However, according to the method for producing a single crystal of the present invention, generation of by-products in the exhaust pipe 14 can be suppressed even when hydrogen halide is used as an etching gas. Therefore, a gas passage space in the exhaust pipe 14 can be secured, and crystals that are generated near the seed substrate 3a and suppress the gas flow can also be removed. For this reason, exhaust gas in the vapor phase growth apparatus S2 can be sufficiently exhausted. Thereby, since the flow rate of the source gas to be flowed can be increased, a bulk single crystal having a thickness larger than that of the conventional one can be manufactured.

  In the case of the manufacturing method as shown in FIG. 2, by flowing the etching gas 10 along the inner wall surface of the apparatus, the etching gas 10 mainly flows between the inner wall surface and the seed substrate 3a and hardly flows to the seed substrate 3a. Thus, it is possible to reduce the occurrence of suppression of growth of the single crystal 3b caused by etching. Further, in the case of the etching gas supply unit 12 shown in FIG. 3, the etching gas 10 flows through the etching gas supply unit 12 along the entire inner wall surface of the second inner cylinder part 2a, and is thus released from the etching gas supply unit 12. The etched etching gas 10 is caused to flow along the entire peripheral surface of the inner wall surface also in the reaction heating chamber 2a. For this reason, the by-product which arose on the inner wall face of the reaction heating chamber 2a can be removed evenly.

The single crystal body 3b obtained by the production method of the present invention as described above has a high quality with a thickness as large as 25 mm or more and a low average dislocation density of 1 × 10 ⁹ cm ⁻² or less.

  Note that the vapor phase growth apparatus using the etching gas has been described based on the apparatus of FIG. 2 in the above description, but the present invention is not limited to this.

  As described above, it is possible to manufacture a bulk type and high quality single crystal substrate suitable for epitaxial growth of a single crystal substrate such as a gallium nitride compound semiconductor applied to an optical element and an electronic element.

  Note that the present invention is not limited to the above-described embodiment, and various modifications may be made without departing from the scope of the present invention.

S1, S2: Vapor phase growth apparatus 1: Support 1a: Susceptor rotating shaft 2: Quartz tube 3a: Seed substrate 3b: (Growth) single crystal 4a, 4b: Heater 5a, 5b: Source gas 6: Carrier gas 9a : Inner cylinder part 9b: Outer cylinder part 10: Etching gas 11: Mixed gas (exhaust gas) of etching gas and source gas
12: Etching gas supply unit 14: Exhaust pipe 15: Heater 16 provided in the exhaust pipe 14: O-ring

Claims (8)

A method for producing a single crystal by vapor deposition,
Supplying a nitrogen-containing gas and a group IIIB element halide on a seed substrate, and reacting the nitrogen-containing gas and the group IIIB element halide on the seed substrate;
The exhaust gas flowed after Step 1 is introduced into an exhaust pipe, and the exhaust gas is introduced at a temperature higher than the vaporization temperature of the compound generated by the reaction between the nitrogen-containing gas and the hydrogen halide gas. Step 2 of heating with a heater provided inside the exhaust pipe;
A method for producing a single crystal comprising:   The method for producing a single crystal body according to claim 1, wherein the heater has a rod shape and is arranged concentrically with the exhaust pipe.   The method for producing a single crystal according to claim 2, wherein the heater includes a wire that generates coiled heat and a protective tube that surrounds the wire. The exhaust pipe is composed of two or more pipes, and a connecting portion of the two pipes is located in the exhaust pipe surrounding the heater in the step 2,
The method for producing a single crystal body according to claim 1, wherein an O-ring is provided in the connection portion.   5. The production of a single crystal according to claim 1, further comprising a step 3 in which the compound heated by the heater in the step 2 is discharged from the exhaust pipe and then cooled and solidified to be collected. Method.   6. The method for producing a single crystal according to claim 1, wherein the vapor phase growth method is a hydride vapor phase growth method. Step 1 is performed in a vapor deposition apparatus,
The method for manufacturing a single crystal according to claim 1, wherein the step 1 includes a step of flowing an etching gas along an inner wall of the vapor phase growth apparatus. The method for producing a single crystal body according to claim 1, wherein the etching gas is hydrogen halide.

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