Method for forming silicon epitaxial layer

A method of forming a silicon epitaxial layer on a semiconductor underlayer of a target substrate in a process chamber configured to be selectively supplied with a hydrogen chloride gas, a hydrogen gas, and a silane gas, the method comprising:

• a pressure reducing step of reducing a pressure inside the process chamber in which the target substrate has been loaded;
• a hydrogen chloride treatment step of performing a supply of the hydrogen chloride gas into the process chamber while stopping a supply of the silane gas into the process chamber, to treat an atmosphere inside the process chamber with the hydrogen chloride gas after the pressure reducing step, wherein the atmosphere inside the process chamber is set to a temperature of 500 to 800° C. and a first reduced pressure in the hydrogen chloride treatment step;
• a hydrogen heat treatment step of performing a supply of the hydrogen gas into the process chamber while stopping the supply of the silane gas and the supply of the hydrogen chloride gas into the process chamber, to treat a surface of the semiconductor underlayer with the hydrogen gas after the pressure reducing step, wherein the atmosphere inside the process chamber is set to a temperature higher than 800° C. and a second reduced pressure in the hydrogen heat treatment step;
• and
• a vapor phase growth step of performing the supply of the silane gas into the process chamber while stopping the supply of the hydrogen chloride gas into the process chamber, to form the silicon epitaxial layer on the semiconductor underlayer by vapor phase growth after the hydrogen chloride treatment step and the hydrogen heat treatment step, wherein the atmosphere inside the process chamber is set to a film forming temperature and a third reduced pressure in the vapor phase growth step.