KR20190078250A - Method for growing sic single crystal - Google Patents

Abstract

Provided is a method for growing a silicon carbide single crystal. The method for growing a silicon carbide single crystal according to the present invention controls a ratio of C/Si so that the silicon carbide single crystal can be grown while preventing intrusion of polymorphs and other polymorphs to be grown before performing a raw material injection step.

Description

METHOD FOR GROWING SIC SINGLE CRYSTAL [0002]

The present invention relates to a silicon carbide single crystal growth method.

Generally,

Semiconductor device materials such as SiC, GaN, AlN and ZnO are attracting attention as next-generation semiconductor device materials as silicon (Si) used as a representative semiconductor device material has physical limitations.

Silicon carbide (SiC) is superior to GaN, AlN and ZnO in terms of thermal stability and oxidation resistance.

Silicon carbide (SiC) has an excellent thermal conductivity of about 4.6 W / Cm ° C and is advantageous in that it can be produced as a large diameter substrate having a diameter of 2 inches or more. Thus, it is more lighted than a substrate such as GaN, AlN and ZnO have.

Such SiC crystals are classified into various types depending on the growth temperature. Among them, SiC is used as a typical silicon carbide (SiC), 6H-SiC single crystal is used as an LED device, and 4H-SiC single crystal is used as a power device.

Currently, a method of manufacturing a 4H-SiC single crystal substrate is gaining popularity in view of environment friendliness and power loss reduction.

In order to manufacture a 4H, 6H-SiC substrate of 2 inches or more, a physical vapor phase transfer method (PVT method) is generally used. A seed crystal (4H, 6H-SiC) is attached on a seed crystal holder, , 6H-SiC), a 4H, 6H-SiC single crystal is grown.

For this purpose, the seed crystal (4H, 6H-SiC) is attached to the seed holder to be in contact. 4H, 6H-SiC single crystal is grown on the seed crystal (4H, 6H-SiC) as the process time passes.

On the other hand, proper temperature and pressure are necessary to grow the 4H-SiC single crystals that are being spotlighted.

When the growth temperature and pressure deviate from a certain range, polymorphs such as 6H or 15R are invaded. Therefore, the temperature and pressure control of the inner wall of the crucible and the crucible center must be controlled so that a high-quality ingot can be grown.

In addition, the temperature difference between the seed center and the edge and the temperature between the seed crystal and the powder is the most important factor controlling the 4H polymorphism.

In general, an inert gas such as argon and nitrogen is supplied during the growth of a single crystal. It is known that the larger the amount of nitrogen, the more easily the 4H polymorphism is controlled.

However, when the amount of nitrogen atoms substituted with carbon atoms is large, nitrogen atoms having a smaller atomic size than carbon atoms may cause problems in lattice distortion or post-processing epitaxy.

Therefore, 4H-SiC should be controlled to have a nitrogen doping concentration of 1.0E + 19 or less.

The present invention provides a silicon carbide single crystal growth method for growing a 4H-SiC single crystal ingot through induction heating or resistance heating, which can obtain a high-quality ingot free from polymorphism while controlling the nitrogen doping concentration to 1.0E + 19 or less I want to.

A silicon carbide single crystal growth method according to an embodiment of the present invention is a method of growing a silicon carbide single crystal using a silicon carbide single crystal growth apparatus including a crucible, a seed crystal, a seed crystal holder, and a heating means.

The silicon carbide single crystal growth method may include a step of charging a raw material into a crucible and a step of mounting a seed holder in a crucible by pulling a seed holder with seed crystal into a hydrocarbon single crystal growth apparatus have.

The silicon carbide single crystal growth method includes an impurity removing step for removing impurities contained in the crucible by heating the crucible, and a purging step for removing air remaining in the crucible by injecting an inert gas into the crucible.

The silicon carbide single crystal growth method may also include a single crystal growth step of heating the crucible to a single crystal growth temperature using a heating means to sublimate the raw material to grow a single crystal.

The silicon carbide single crystal growth method is characterized in that before the step of injecting the raw material, the carbon and silicon ratio control which controls the ratio of C / Si is controlled so that the silicon carbide single crystal can be grown while preventing the intrusion of polymorphism and other polymorphism Step < / RTI >

The step of controlling the ratio of carbon and silicon may include a step of adding a carbon powder to adjust the ratio of carbon to silicon by adding carbon powder to the raw material silicon carbide (SiC) powder.

In the step of adding the carbon powder, the carbon powder may be added in a proportion of 2 to 10 wt% based on the weight of the silicon carbide powder.

The particle size of the carbon powder in the step of adding the carbon powder may be set in the range of 5 to 20 mu m.

According to the embodiment of the present invention, by controlling the C / Si ratio by adding carbon powder to the silicon carbide powder, it is possible to form an atmosphere capable of growing 4H-SiC single crystal without intrusion of polymorphism and other polymorphism have.

Thus, a high quality single crystal (ingot) can be obtained by controlling various defects.

1 is a schematic cross-sectional view of a hydrocarbon single crystal growth apparatus used in a hydrocarbon single crystal growth method according to an embodiment of the present invention.
2 is a schematic configuration diagram of a silicon carbide single crystal growth method according to an embodiment of the present invention.
3 is a photograph of the sample of Table 1 taken using a UVF analyzer showing the result of comparison with the addition of carbon powder.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Wherever possible, the same or similar parts are denoted using the same reference numerals in the drawings.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms as used herein include plural forms as long as the phrases do not expressly express the opposite meaning thereto. Means that a particular feature, region, integer, step, operation, element and / or component is specified, and that other specific features, regions, integers, steps, operations, elements, components, and / And the like.

All terms including technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention belongs. Predefined terms are further interpreted as having a meaning consistent with the relevant technical literature and the present disclosure, and are not to be construed as ideal or very formal meanings unless defined otherwise.

1 is a schematic cross-sectional view of a hydrocarbon single crystal growth apparatus used in a hydrocarbon single crystal growth method according to an embodiment of the present invention.

1, a hydrocarbon single crystal growth apparatus includes a crucible 200 to which a raw material 100 is charged, a seed holder 600 to which a seed crystal 500 is attached,

And a heat insulating material 300 surrounding the crucible 200.

The hydrocarbon single crystal growth apparatus includes a quartz tube 400 having upper and lower openings and surrounding the heat insulating material 300 and a heater 400 for heating the crucible 200 from the outside of the quartz tube 400 by an induction heating method Means 700 may be included.

The upper and lower portions of the quartz tube 400 may be closed by a flange (not shown).

And may include a guide 610 spaced apart from the seed holder 600 and positioned on the inner circumferential surface of the crucible 200.

The crucible 200 may be heated by induction heating in the quartz tube 400.

The crucible 200 is preferably made of a material having a melting point higher than the sublimation temperature of silicon carbide (SiC). For example, a material made of graphite or having a melting point higher than the sublimation temperature of silicon carbide (SiC) on the graphite material may be applied.

The seed holder 600 is manufactured by using high-density graphite as means for supporting the seed crystal 500.

The seed holder 600 with the seed crystal 500 attached thereto is mounted on top of the crucible 200 to form a single crystal on the seed crystal 600.

The heat insulating material 300 and the quartz tube 400 are provided outside the crucible 200 to maintain the temperature of the crucible 200 at a crystal growth temperature.

The guide 610 functions to guide the raw material 100 to be sublimated and attached to the seed crystal 500 easily.

The heating means 700 is provided outside the quartz tube 400 and heats the crucible 200 by an induction heating method using a high frequency induction coil to heat the raw material 100 in the crucible 200 into a single crystal Heat to the temperature for sexual maturity.

A method of growing silicon carbide single crystal according to an embodiment of the present invention includes growing a single crystal by using a silicon carbide single crystal growing apparatus including a crucible 200, a seed crystal 500, a seed crystal holder 600, .

The silicon carbide single crystal growth method may include a step S10 of loading a raw material into the crucible 200 to load the raw material 100 therein.

After the raw material charging step S10 is performed, the seed holder 600 with the seed crystal 500 attached thereto is drawn into a hydrocarbon single crystal growth apparatus (not shown) The positive holder mounting step (S20) can be performed.

After the seed holder holder mounting step S20 is performed, an impurity removing step (S30) for removing the impurities contained in the crucible 200 by heating the crucible 200 under the set temperature and pressure can be performed.

After the impurity removing step S30 is performed, an inert gas such as argon and nitrogen is injected into the crucible 200 to remove air remaining in the crucible 200 and between the crucible 200 and the heat insulating material 300 A purging step (S40) may be performed.

After the purging step S40, the single crystal growth step (S50) in which the crucible 200 is heated to the single crystal growth temperature using the heating means 700 to sublimate the raw material 100 to grow a single crystal can be performed have.

Before performing the step of injecting the raw material (S10), a carbon and silicon ratio control step (step S11) is performed to control the ratio of C / Si so that the silicon carbide single crystal can be grown while preventing intrusion of polymorphism and other polymorphism S11) can be performed.

The carbon and silicon ratio control step S11 may include a carbon powder addition step S12 for adding a carbon particle to the silicon carbide powder as a raw material to control the ratio of carbon to silicon.

In addition, in the carbon powder addition step (S12), the carbon powder may be added in a proportion of 2 to 10 wt% with respect to the weight of the silicon carbide powder so that the ratio of carbon to silicon can be accurately controlled at a desired ratio.

In the carbon powder addition step (S12), the carbon powder may be added in a proportion of 5 to 10 wt% based on the weight of the silicon carbide powder so that the ratio of carbon to silicon can be controlled more precisely at a desired ratio.

In addition, in the carbon powder addition step (S12), the particle size of the carbon powder can be set in the range of 5 to 20 mu m so as to more accurately control the ratio of carbon to silicon at a desired ratio.

The seed crystal 500 in the seed crystal holder attaching step S20 may be attached to the seed crystal holder 600 in advance using an adhesive or the like before carrying out the seed crystal holder attaching step S20.

The impurity removing step S30 may be performed by heating the crucible 200 for a set time, for example, 2 hours to 3 hours at a temperature of less than 1000 占 폚 and a vacuum pressure.

The purging step S40 may be performed by injecting an inert gas such as argon and nitrogen gas into the crucible 200. [

In the single crystal growth step S50, the crucible 200 is heated to 2000 ° C. to 3000 ° C. by using the heating means 700, and then the raw material 100 is sublimed by pressure reduction to 0.2 to 20 torr, Respectively.

Hereinafter, a process of a silicon carbide single crystal growth method according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG.

In the silicon carbide single crystal growth method, a single crystal was grown on the seed crystal (500) by the PVT method.

For this purpose, in order to control the ratio of C / Si so that the silicon carbide single crystal can be grown while preventing the polymorphism and other polymorphism to be grown first, the carbon powder is mixed with the silicon carbide (SiC) powder Lt; / RTI >

At this time, the carbon powder is added in a proportion of 2 to 10 wt% with respect to the weight of the silicon carbide powder, and the particle size of the carbon powder is formed in the range of 5 to 20 μm.

Thus, silicon carbide (SiC) powder (D50 to 200 mu m) to which carbon powder is added is charged into the crucible 200.

Then, the seed crystal 500 and the seed crystal holder 600 made of silicon carbide are fixed to the top of the crucible 200, and then introduced into the hydrocarbon single crystal growth apparatus.

Then, in order to remove the impurities contained in the crucible 200 prior to the growth of the single crystal, the crucible is heated at a temperature of less than 1000 占 폚 at a vacuum pressure for 2 to 3 hours.

Then, argon and nitrogen gas, which are inert gases, are injected into the crucible 200 to remove air remaining in the crucible 200 and between the crucible 200 and the heat insulating material 300.

 In the single crystal growth step S50, the crucible 200 is heated to a temperature of 2000 to 2300 DEG C by using the heating means 700, and then the inside of the silicon carbide single crystal growth apparatus is reduced to 0.2 to 20 torr, So that the seed crystal 500 is grown by single crystal growth.

Thus, by adding carbon powder to the raw material silicon carbide powder at a predetermined ratio, the ratio of carbon to silicon can be accurately controlled during the growth of silicon carbide single crystal.

Accordingly, the silicon carbide single crystal can be grown while controlling the ratio of carbon to silicon to prevent intrusion of the polymorphism and other polymorphism to be grown into silicon carbide single crystal.

Therefore, it is possible to control the polymorphism by increasing the ratio of carbon to silicon while supplying a small amount of nitrogen gas, which is an atmospheric gas, in the growth of silicon carbide single crystal.

(Example)

4H-SiC single crystal was grown by adjusting the ratio of silicon carbide (SiC) powder to carbon powder to 5 wt% based on weight.

After monocrystal growth, the incorporation of polymorphism was confirmed using UVF (Ultra Violet Fluorescence) analyzer of different colors according to energy band gap difference. As a result, polymorphism other than 4H such as 6H or 15R did not invade (refer to FIG. 3) .

(Comparative Example)

Samples (A to E) of Table 1 in which the ratio of silicon carbide powder and carbon powder were adjusted to 0 wt%, 1 wt%, 2 wt%, 5 wt%, and 10 wt%, respectively, Was confirmed by UVF analysis after single crystal growth as in the examples (see Fig. 3).

[Table 1]

In the case of Sample A in which no carbon powder was contained, it can be seen that the conversion from 4H (green) to 6H (yellow) and 15R (orange) was performed during the growth of the single crystal.

It can be seen that 6H penetrates even in the case of the sample B in which the ratio of the carbon powder is 1 wt% and in the case of the sample C in which the carbon powder ratio is 2 wt%. However, in the case of Sample C, it can be seen that 6H penetrated into a range much smaller than that of Sample B.

Further, in the case of the samples D and E in which the carbon powder ratio is 5 wt% and 10 wt%, the amount of the carbon (C) powder is sufficiently large, and it can be seen that all of 4H is stably grown.

100: raw material
200: Crucible
300: Insulation
400: quartz tube
500: seed seed
600: seed holder
700: heating means

Claims (4)

A method for growing a silicon carbide single crystal by using a silicon carbide single crystal growing apparatus including a crucible, a seed crystal, a seed crystal holder, and a heating means,
A step of charging a raw material into the crucible,
A seed holder holding step of pulling the seed holder with the seed crystal into a hydrocarbon single crystal growth apparatus and mounting the seed holder on an upper part of the crucible;
An impurity removing step of heating the crucible to remove impurities contained in the crucible,
A purging step of injecting an inert gas such as argon and nitrogen into the crucible to remove air remaining in the crucible,
A single crystal growing step of heating the crucible to a single crystal growth temperature by using the heating means to sublimate the raw material to grow a single crystal,
A carbon and silicon ratio control step of controlling the ratio of C / Si so that the silicon carbide single crystal can be grown while preventing the intrusion of the polymorphism and other polymorphs to be grown,
Wherein the silicon carbide single crystal growth method comprises: The method according to claim 1,
Wherein the step of controlling the ratio of carbon and silicon comprises adding a carbon powder to a silicon carbide (SiC) powder as a raw material to adjust the ratio of carbon to silicon. 3. The method of claim 2,
Wherein the carbon powder is added in a proportion of 2 to 10 wt% based on the weight of the silicon carbide powder in the step of adding the carbon powder. The method according to claim 2 or 3,
Wherein the particle size of the carbon powder in the step of adding the carbon powder is set in the range of 5 to 20 mu m.

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