KR101673261B1 - P-type silicon carbide single crystal and growing method for the same - Google Patents

Abstract

A P-type silicon carbide single crystal and a growing method thereof are disclosed. One embodiment of the present invention is a method for manufacturing a semiconductor device, comprising: preparing a mixed powder of Al ₃ C ₄ powder and SiC powder; Charging the mixed powder into the bottom of the crucible; Mounting a SiC seed crystal on top of the crucible; And heating the crucible equipped with the SiC seed crystal to a growth temperature and then growing the single crystal by sublimating the mixed powder charged in the crucible, wherein the crucible equipped with the SiC seed crystal is heated to a growth temperature And growing a single crystal by sublimation of mixed powder charged in the crucible, wherein N ₂ A method for growing a P-type silicon carbide single crystal, which stabilizes a crystal polymorphism by supplying a gas.

Description

P-TYPE SILICON CARBIDE SINGLE CRYSTAL AND GROWING METHOD FOR THE SAME BACKGROUND OF THE INVENTION 1. Field of the Invention [0001]

One embodiment of the present invention relates to a P-type silicon carbide single crystal and a growth method thereof.

SiC (silicon carbide) is a typical next-generation semiconductor element material, and has excellent thermal stability and excellent oxidation resistance. In addition, it has an excellent thermal conductivity of about 4.6 W / Cm ° C and can be produced as a substrate having a diameter of 4 inches or more. Physical vapor transport (PVT) is widely used because of its high yield and high quality silicon carbide by the SiC single crystal growth method.

Meanwhile, recently, as the technology of semiconductor companies has developed remarkably, a power semiconductor device having high voltage (600V ~ 2,000V) such as SiC-SBD and SiC-MOSFET can be realized. In addition, development of a SiC-IGBT power device having a higher voltage (> 2,000 V) is progressing, but the development is relatively delayed due to the structural limitations of the vertical device. SiC-IGBTs have multiple nested structures stacked several times in the order of n-type, p-type or p-type n-type. When an n-type SiC substrate is used, a large number of charges in a channel When the p-type SiC substrate is used, it becomes an electron.

In general, SiC has a higher mobility than electrons, so n-type substrates with a large number of electrons have been developed at a relatively advanced stage, while p-type substrate development has been delayed. Therefore, a p-type substrate is required to realize a SiC IGBT device, and electrons can be used with a large number of charges by using the p-type substrate, thereby greatly improving the performance of the device.

However, there are some limitations in producing a p-type substrate in the physical vapor phase transfer method (PVT method). First, the n-type doping material is a nitrogen-based gas phase, and the p-type is a solid phase such as boron and aluminum, so that the sublimation effect is large due to the difference in vapor pressure. Second, in the case of SiC, various types of polytypes exist depending on the lamination period and the crystal structure. Nitrogen, which is an n-type doping material, contributes to 4H-SiC polymorphism stabilization. Therefore, if nitrogen is not added for p-type production, polymorphic inclusion such as 6H or 15R is produced. Finally, since the resistivity of the p-type substrate is higher than that of the n-type, the electron mobility is relatively low, so that the substrate resistance must be lowered (p type:> 1 Ωcm, n type: ~ 0.015 Ωcm).

In one embodiment of the present invention, polymorphism control is facilitated by adding aluminum carbide (Al ₃ C ₄ ) as a p-type doping material to reduce the influence on the difference in vapor pressure and simultaneously doping nitrogen (Nitrogen) Type p-type silicon carbide single crystal having a resistance of 1? Cm or less, and a method for growing the p-type silicon carbide single crystal.

In one embodiment of the present invention, Al ₃ C ₄ Preparing a mixed powder of powder and SiC powder; Charging the mixed powder into the bottom of the crucible; Mounting a SiC seed crystal on top of the crucible; And heating the crucible equipped with the SiC seed crystal to a growth temperature and then growing the single crystal by sublimating the mixed powder charged in the crucible, wherein the crucible equipped with the SiC seed crystal is heated to a growth temperature And growing a single crystal by sublimation of mixed powder charged in the crucible, wherein N ₂ A method for growing a P-type silicon carbide single crystal, which stabilizes a crystal polymorphism by supplying a gas.

The content of Al ₃ C ₄ powder in the mixed powder may be 5 to 10 wt%.

The content of SiC powder in the mixed powder may be 90 to 95 wt%.

The growth temperature may be 1,800 to 2,000 DEG C at atmospheric pressure.

The growth temperature may be 1,850 to 1,950 DEG C under atmospheric pressure.

The growth of the single crystal may be carried out while being maintained at a growth pressure of 1 to 20 torr.

The N ₂ The gas may be fed independently or in the form of a mixed gas mixed with an inert gas containing Ar gas.

The ratio of the N ₂ gas to the inert gas may be 15 to 25 vol%.

Mounting a SiC seed crystal on top of the crucible; Thereafter, the crucible may be heated to a vacuum pressure of less than 1,000 ° C. to remove impurities in the crucible.

Heating the crucible to a vacuum pressure and less than 1,000 ° C to remove impurities in the crucible, and the heating may be performed for 2 to 3 hours.

Mounting a SiC seed crystal on top of the crucible; Thereafter, an inert gas containing Ar gas is injected into the crucible to purging the air in the crucible.

The step of purging the air in the crucible by injecting an inert gas containing Ar gas into the crucible may be repeated two or more times.

Another embodiment of the present invention provides a P-type silicon carbide single crystal which is produced by the above-described method for producing a P-type silicon carbide single crystal and contains a single crystal polymorphism and has a resistivity of more than 0 and 1 cm or less.

According to an embodiment of the present invention, it is possible to manufacture a low-resistance p-type silicon carbide single crystal of 1 Ωcm or less by utilizing the simultaneous doping of aluminum carbide (Al ₃ C ₄ ) and nitrogen (Nitrogen) Type P-type silicon carbide single crystal and a method of growing the same.

1 is a flowchart illustrating a method of growing a P-type silicon carbide single crystal according to an embodiment of the present invention.
2 is a schematic view showing a P-type silicon carbide single crystal growing apparatus according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited thereto, and the present invention is only defined by the scope of the following claims.

Throughout the specification, when an element is referred to as " comprising ", it means that it can include other elements as well, without excluding other elements unless specifically stated otherwise.

In one embodiment of the present invention, Al ₃ C ₄ Preparing a mixed powder of powder and SiC powder (SlOO); Charging the mixed powder to the bottom of the crucible (S200); Mounting a SiC seed crystal on the crucible (S300); And a step (S400) of growing a single crystal by sublimation of the mixed powder charged in the crucible after the temperature of the crucible equipped with the SiC seed crystal is raised to a growth temperature, wherein the crucible equipped with the SiC seed crystal is heated to a growth temperature Heating the mixed powder charged in the crucible and growing a single crystal, wherein N ₂ A method for growing a P-type silicon carbide single crystal, which stabilizes a crystal polymorphism by supplying a gas.

1 is a flowchart illustrating a method of growing a P-type silicon carbide single crystal according to an embodiment of the present invention.

According to one embodiment of the present invention, aluminum carbide (Al ₃ C ₄ ) is sublimated and decomposed into aluminum and carbon. At this time, aluminum is substituted for the silicon site to form p-type doping, and the remaining carbon contributes to 4H-SiC crystal polymorphism stabilization by making a carbon rich atmosphere together with the SiC raw material powder. Compared to the case of using a single element, the vapor pressure is relatively low, so that the resistance value can be controlled by suppressing the phenomenon of excessive pumping.

Further, according to an embodiment of the present invention, a low-resistance P-type silicon carbide single crystal can be produced by contributing to the stabilization of the crystal polymorphism by the nitrogen (N ₂ ) gas and lowering the resistance value by bonding with Al-N .

Al ₃ C ₄ for the mixed powder The content of the powder is preferably 5 to 10 wt%. Al ₃ C ₄ When the content of the powder is less than 5 wt%, the P-type doping is difficult to be performed, and when the content is more than 10 wt%, the resistance value is increased due to excessive pumping.

The content of SiC powder in the mixed powder is preferably 90 to 95 wt%. When the SiC powder content is less than 90 wt%, aluminum, nitrogen and the like are excessively doped, and when the SiC powder content is more than 95 wt%, doping is inhibited.

The growth temperature may be 1,800 to 2,000 ° C at atmospheric pressure, and more preferably 1,850 to 1,950 ° C. When the growth temperature is lower than 1,800 DEG C, the specific resistance is increased even under the same conditions. This is because the vapor pressure of aluminum is high and the aluminum sublimes quickly at a relatively low temperature. On the other hand, when the temperature exceeds 2,000 DEG C, the specific resistance is decreased, but there is a problem that a crystalline polymorphism such as 6H or 15R is mixed.

The reason for maintaining the atmospheric pressure at this time is to prevent undesired crystal polymorphism from occurring at the initial stage of crystal growth. That is, the mixed powder charged in the crucible is maintained at atmospheric pressure, the temperature of the mixed powder is raised to the growth temperature, and the mixed powder is sublimed while the internal pressure is reduced to 1 to 20 torr to grow single crystals.

, Comprising the steps of: After raising the crucible equipped with the SiC seed affection to the growth temperature, to transform the mixed powder charged in the crucible in growing a single crystal, one embodiment of the invention, as described above; in, N ₂ Gas, wherein the N2 < RTI ID = 0.0 _> The gas may be supplied independently or in the form of a mixed gas mixed with an inert gas containing Ar gas.

Here, when supplied in the form of a mixed gas mixed with an inert gas containing Ar gas, the N ₂ The ratio of the gas is preferably 15 to 25 vol%. The N2 < RTI ID = 0.0 _> If the ratio of the gas is less than 15 vol%, the bonding force between Al-N is reduced to make it impossible to fabricate a substrate with low resistance. If it exceeds 25 wt%, n-type doping may occur.

Hereinafter, examples of the present invention will be described. However, the following examples are only illustrative of the present invention and are not intended to limit the scope of the present invention.

Example

2 is a schematic view showing a P-type silicon carbide single crystal growing apparatus according to an embodiment of the present invention.

2, a P-type silicon carbide single crystal growth apparatus according to an embodiment of the present invention includes a crucible 100 provided with an internal space for charging a mixed powder of an Al ₃ C ₄ powder 10 and a SiC powder 20, A heat insulating material 200 surrounding the crucible 100 and the quartz tube 300 and a heating means 400 provided outside the quartz tube 300 for heating the crucible 100. In one embodiment, a single crystal is grown on the seed crystal 500 using physical vapor transport (PVT).

Example  One

Al ₃ C ₄ is added to the bottom of the crucible 100 A mixed powder containing 7.5 wt% of powder and 92.5 wt% of SiC powder was charged. Also, a mixed gas of nitrogen (N ₂ ) + argon (Ar) was prepared so as to be injected into the crucible. At this time, nitrogen (N 2) for argon (Ar) The gas ratio was 20 vol%.

A seed crystal made of silicon carbide (SiC) is provided and mounted on the upper part of the crucible. The crucible having the seed crystal bonded thereto was introduced into the growth apparatus and heated at a vacuum pressure of less than 1,000 DEG C for 2 to 3 hours to remove impurities contained in the crucible.

Then, an inert gas such as argon (Ar) gas was injected to remove the air remaining in the crucible and between the crucible and the heat insulating material. Here, the purging process using an inert gas was performed about 2 to 3 times.

Subsequently, the pressure was raised to atmospheric pressure, and then the crucible was heated to a temperature of 1,800 to 2,000 DEG C using a heating means. Here, the reason for maintaining the atmospheric pressure is to prevent the generation of undesired crystal polymorphism at the initial stage of crystal growth.

That is, the mixed powder was first heated to the growth temperature while maintaining the atmospheric pressure, and the mixed powder was sublimed while growing the inside of the growth apparatus at a growth pressure of 1 to 20 torr to grow single crystals.

Example  2

In Example 1, Al ₃ C ₄ Single crystal was grown in the same manner as in Example 1, except that 12.5 wt% of powder and 87.5 wt% of SiC powder were used.

Comparative Example  One

In Example 1, Al ₃ C ₄ A single crystal was grown in the same manner as in Example 1, except that 2.5 wt% of powder and 97.5 wt% of SiC powder were used.

Comparative Example  2 to 4

In Example 1, Al ₃ C ₄ Only SiC powder was used instead of the mixed powder of powder and SiC powder, and nitrogen Single crystals were grown in the same manner as in Example 1, except that 10 vol%, 20 vol%, and 30 vol% of gases were used, respectively.

Comparative Example  5

In Example 1, a single crystal was grown in the same manner as in Example 1, except that no nitrogen (N ₂ ) gas was injected.

Comparative Example  6

In Example 2, a single crystal was grown in the same manner as in Example 2 except that no nitrogen (N ₂ ) gas was injected.

Comparative Example  7

In Example 3, a single crystal was grown in the same manner as in Example 3, except that no nitrogen (N ₂ ) gas was injected.

evaluation

The ingots grown according to Examples 1 and 2 and Comparative Examples 1 to 7 were cut and processed to confirm the crystal polymorphism and conduction type.

Dopant Al ₃ C ₄
(wt%) SiC
(wt%) N ₂ / Ar Crystalline polymorph Conductive type Resistivity
(Ω cm) Example 1 Al ₃ C ₄ + N + SiC 7.5 92.5 20/100 4H P type 0.78 Example 2 Al ₃ C ₄ + N + SiC 12.5 87.5 20/100 P type 1.23 Comparative Example 1 Al ₃ C ₄ + N + SiC 2.5 97.5 20/100 n type - Comparative Example 2 N + SiC - 100 10/100 n type - Comparative Example 3 N + SiC - 100 20/100 n type - Comparative Example 4 N + SiC - 100 30/100 n type - Comparative Example 5 Al ₃ C ₄ + SiC 2.5 97.5 - 4H + 6H + 15R (mixed) P type - Comparative Example 6 Al ₃ C ₄ + SiC 7.5 92.5 - P type - Comparative Example 7 Al ₃ C ₄ + SiC 12.5 87.5 - P type -

Referring to Table 1, in Examples 1 and 2, 4H, p type single crystals were observed. As a result of the resistivity measurement using the Hall effect, it was confirmed that the resistance value increases as the weight of the p-type doping material increases.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims. As will be understood by those skilled in the art. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

10: Al ₃ C ₄ Powder 20: SiC powder
100: Crucible 200: Insulation
300: quartz tube 400: heating means
500: seed seed

Claims (13)

Preparing a mixed powder of Al ₃ C ₄ powder and SiC powder;
Charging the mixed powder into the bottom of the crucible;
Mounting a SiC seed crystal on top of the crucible; And
Heating the crucible equipped with the SiC seed crystal to a growth temperature and then sublimating the mixed powder charged in the crucible to grow a single crystal;
Lt; / RTI >
The content of Al ₃ C ₄ powder in the mixed powder is 5 to 10 wt%
The content of SiC powder in the mixed powder is 90 to 95 wt%
Heating the crucible equipped with the SiC seed crystal to a growth temperature and then sublimating the mixed powder charged in the crucible to grow a single crystal,
N ₂ gas is supplied to stabilize the crystal polymorphism,
Wherein the crystalline polymorphism is 4H.
delete delete The method according to claim 1,
Wherein the growth temperature is 1,800 to 2,000 DEG C at atmospheric pressure.
5. The method of claim 4,
Wherein the growth temperature is 1,850 to 1,950 DEG C at atmospheric pressure.
The method according to claim 1,
The growth of the single crystal
Wherein the growth is carried out at a growth pressure of 1 to 20 torr.
The method according to claim 1,
The N ₂ Wherein the gas is supplied independently or in the form of a mixed gas mixed with an inert gas containing an Ar gas.
8. The method of claim 7,
The N2 < RTI ID = 0.0 _> Wherein the ratio of the gas is 15 to 25 vol%.
The method according to claim 1,
Mounting a SiC seed crystal on top of the crucible; Since the,
Heating the crucible to a vacuum pressure of less than 1,000 ° C to remove impurities in the crucible;
Wherein the P-type silicon carbide single crystal growth method further comprises:
10. The method of claim 9,
Heating the crucible to a vacuum pressure of less than 1,000 DEG C to remove impurities in the crucible,
Wherein the heating is performed for 2 to 3 hours.
The method according to claim 1,
Mounting a SiC seed crystal on top of the crucible; Since the,
Injecting an inert gas containing Ar gas into the crucible to purge the air in the crucible;
Wherein the P-type silicon carbide single crystal growth method further comprises:
12. The method of claim 11,
Injecting an inert gas containing Ar gas into the crucible to purge the air in the crucible;
Wherein the p-type silicon carbide single crystal growth is repeated twice or more.
13. A process for the preparation of a compound according to any one of claims 1 to 12,
Wherein the P-type silicon carbide single crystal contains a single crystalline polymorph, and the resistivity is more than 0 and 1? Cm or less.

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