| 摘要 |
PROBLEM TO BE SOLVED: To restrain deterioration of crystallinity of a surface of a gallium nitride based compound semiconductor in the course of cooling, by growing a gallium nitride based compound semiconductor thin film, and cooling a substrate in atmospheric gas composed of material gas containing at least nitrogen element and nitrogen gas. SOLUTION: A substrate 2 composed of sapphire is mounted in a reaction tube 1. After a surface is cleaned, a buffer layer is grown, and a gallium nitride based compound semiconductor thin film is grown to be 2 μm thick. After that, supply of subcarrier gas of trimethyl gallium as material gas and Cp2 Mg(biscyclopentadienyl-Mg) gas is stopped, and the temperature of the substrate 2 is reduced down to 400 deg.C while nitrogen gas as main carrier gas and ammonia as atmospheric gas are newly made to flow. When the substrate temperature reaches 400 deg.C, ammonia is stopped, and the substrate temperature is reduced down to a room temperature while only nitrogen gas as atmospheric gas is made to flow. After cooling is performed down to a room temperature, a wafer is taken out from the reaction tube 1. |
