Method for cleaning SiC monocrystal growth furnace

A method of cleaning a SiC monocrystal growth furnace by using a gas to clean a SiC monocrystal growth furnace provided with an in-furnace substrate composed of a 3C—SiC polycrystal having at least a surface in which an intensity ratio of a (111) plane with respect to other crystal planes is at least 85% but not more than 100% according to powder XRD analysis, the method comprising:

• flowing a mixed gas in a non-plasma state through an inside of the SiC monocrystal growth furnace, thereby selectively removing a SiC deposit deposited inside the SiC monocrystal growth furnace,
• wherein the SiC deposit is a 3C—SiC polycrystal having an intensity ratio of the (111) plane with respect to the other crystal planes of less than 85% according to powder XRD analysis,
• wherein the mixed gas comprises at least 1 vol % but not more than 20 vol % of F2 gas, and at least 80 vol % but not more than 99 vol % of the inert gas, and a temperature of the inside the SiC monocrystal growth furnace is 280° C. 400° C.,
• wherein the in-furnace substrate comprises an inner wall and members of the SiC monocrystal growth furnace, and
• wherein the mixed gas consists of F2 gas and an inert gas, or consists of F2 gas, an inert gas and air.