Manufacturing method and apparatus for manufacturing silicon carbide epitaxial wafer

Abstract

A manufacturing method for manufacturing a silicon carbide epitaxial wafer includes: introducing a cleaning gas into a growth furnace to remove dendrite-like polycrystal of silicon carbide attached to an inner wall of the growth furnace; after introducing the cleaning gas, bringing a silicon carbide substrate in the growth furnace; and growing a silicon carbide epitaxial layer on the silicon carbide substrate by introducing a processing gas into the growth furnace to manufacture a silicon carbide epitaxial wafer, wherein the cleaning gas having fluid energy of 1.6E−4 [J] or higher is introduced into the growth furnace.

Description

BACKGROUND OF THE INVENTIONField of the Invention[0001]The present invention relates to a manufacturing method and apparatus for manufacturing a silicon carbide epitaxial wafer.Background Art[0002]In recent years, a silicon carbide (hereinafter referred to as SiC) semiconductor has attracted attention mainly as a material for power devices for power control because its bandgap, dielectric breakdown electric field intensity, saturated drift speed and thermal conductivity are higher than those of silicon semiconductors. In fact, a power device using the SiC semiconductor is capable of largely reducing power loss, being reduced in size and realizing energy saving at the time of power supply power conversion and can therefore be a key device for, for example, improving the performance of electric vehicles and improving the functions of solar battery systems or the like in realization of a low-carbon society.[0003]In making a SiC power device, a layer to be provided as an active region o...

AI Technical Summary

Benefits of technology

The present invention provides a method and apparatus for manufacturing silicon carbide epitaxial wafers with reduced crystal defects while avoiding damage to the growth furnace and wafer holder. This is achieved by introducing a cleaning gas with high fluid energy into the growth furnace. The technical effects include improved quality of the manufactured wafers and reduced production costs.

Problems solved by technology

If the silicon carbide epitaxial wafer has defects, the silicon carbide semiconductor device locally fails to hold a high voltage, resulting in generation of a leak current.

The attached silicon carbide is structurally brittle and can therefore form silicon carbide particles easily.

If silicon carbide particles are attached to the wafer surface, crystal defects such as downfalls and triangular defects are generated starting from the attachment points.

In the case of the method disclosed in Japanese Patent No. 5542560, not only the attached silicon carbide but also the silicon carbide film formed as protective film on internal members of the growth furnace and the wafer holder is etched and it is, therefore, difficult to perform cleaning management.

Also, special expelling equipment is required to enable use of chlorine trifluoride, for example, because it corrodes the apparatus and piping.

The method thus entails problems in terms of operation and cost.

Further, because the rate of etching of silicon carbide is lower than that of etching of silicon, a long time is taken to complete cleaning and it is difficult to completely remove silicon carbide.

In the case of the method disclosed in Japanese Patent Laid-Open No. 2014-154865, iodine heptafluoride, which does not etch graphite, is used but the silicon carbide film formed as protective film on the wafer holder and internal members of the growth furnace are thereby etched, as in the case of the method disclosed in Japanese Patent No. 5542560, and it is difficult to perform cleaning management.

Thus, use of a fluorine-based gas as cleaning gas entails the problem of members other than the attached silicon carbide being etched.

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