JPH085654B2 - Method for producing SiC powder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a method for producing SiC powder most suitable as a raw material for a sublimation method.

(B) Conventional technology Since SiC single crystal is a material that is physically and chemically stable and can withstand high temperatures and radiation, it is expected to be applied as an environment-resistant semiconductor material. In particular, 6H-type SiC single crystal has a band gap of about 3.0 eV at room temperature and is used as a material for blue light emitting diodes.

When growing such a SiC single crystal ingot, a sublimation method is mainly adopted. A conventional method for growing a p-type SiC single crystal by this sublimation method is Al.
(Aluminum) powder is mixed with SiC crystal, and this is used as a raw material and heated and sublimated under a low pressure of 1 to 10 Torr to dope vaporized Al in the process of growing the SiC single crystal on the seed crystal consisting of the SiC single crystal. There is a way to do it (“Physical properties” 19
May 1970, P263-P.269).

However, in the above method, the growth temperature is 2000 to 2500 ° C.
Since it is extremely higher than the boiling point (1500 to 1600 ° C) of Al, only Al vaporizes during the temperature rise to the growth temperature. For this reason, the carrier concentration of Al was very high at the early stage of growth of the SiC single crystal, and the carrier concentration of Al decreased as the growth progressed, and finally the n-type SiC single crystal containing no Al grew. .

In addition, Al vaporized before reaching the growth temperature adheres to the surface of the seed crystal, which deteriorates the crystallinity of the SiC single crystal grown on the surface.

Therefore, it is conceivable to use SiC powder in which impurities are doped in advance as a raw material used in the sublimation method. According to such a method, since SiC and impurities are crystallographically bonded, the impurities do not vaporize alone even when the raw material is heated to a high temperature.

(C) Problems to be Solved by the Invention However, conventionally, no consideration has been given to the method for producing SiC powder doped with a predetermined amount of impurities.

For example, in the conventionally known SiC manufacturing methods such as the Acheson method and the silica reduction carbonization method, SiC that becomes an abrasive, a heat-resistant mechanical material, etc.,
That is, since the purpose was only to manufacture SlC that does not require impurity doping, no consideration was given to manufacturing SiC powder in which a predetermined amount of impurities were doped.

(D) Means for Solving the Problems The present invention has been made in view of the above points, and a structural feature thereof is a method for producing a SiC powder doped with a predetermined amount of impurities, wherein the impurities are And SiC powder are heat-treated in an inert gas atmosphere at 1800 ° C. or higher.

(E) Action When SiC powder is heated to 1800 ℃ or higher, SiC decomposes and crystallizes with impurities.

(F) Example As an example of the present invention, SiC powder not doped with impurities and Al as an impurity were placed in a closed container in an Ar gas (inert gas) atmosphere, and SiC and Al
Is heated for a predetermined time.

FIG. 1 shows the Al doping amount (Al) in the SiC powder when the heating temperature, the Ar gas pressure, the heating time, and the Al amount (Al addition amount) relative to the SiC powder were variously changed.
Quantitative value) is shown.

As is clear from FIG. 1, the amount of Al doped in the SiC powder can be set to a predetermined value by changing the conditions such as the heating temperature.

Also, for example, if the Ar gas pressure is changed while the heating temperature is 2250 ° C to 2300 ° C, the heating time is 1 hour, and the amount of Al added is fixed at 0.5 at.%, The Ar gas pressure changes as shown in Fig. 2. Therefore, the quantitative value of Al also changes. It was confirmed by experiments that this tendency was the same even when various conditions other than Ar gas pressure were changed.

Therefore, the quantitative value of Al can be arbitrarily set only by changing the Ar gas pressure.

In addition, although the heating temperature is set to 2200 ° C. to 2400 ° C. in this example, it was confirmed by an experiment that such a temperature may be 1800 ° C. or higher, which is the decomposition start temperature of SiC. Although Ar gas is used as the inert gas, other inert gas such as He may be used.

(G) Effect of the Invention According to the method of the present invention, it is possible to dope impurities into the SiC powder with good controllability.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention, and FIG. 2 is a schematic diagram showing the relationship between Ar gas pressure and Al quantitative value.

Claims (1)

[Claims] 1. A method for producing a SiC powder doped with a predetermined amount of impurities, wherein the impurities and the SiC powder are heat-treated in an inert gas atmosphere at 1800 ° C. or higher.
Method of manufacturing SiC powder.