Method for processing substrate

A processing method of a substrate, wherein the substrate is processed by a substrate processing apparatus, and the substrate processing apparatus comprises a reaction chamber and a secondary chamber surrounding the reaction chamber, the method comprising:

• placing the substrate in the reaction chamber;
• performing a process to increase a pressure in the reaction chamber and a pressure in the secondary chamber, such that the pressure in the secondary chamber is between an atmospheric pressure and the pressure in the reaction chamber and performing at least one cycle of steps which comprise:
• supplying a supercritical fluid and a reaction material into the reaction chamber, so as to increase the pressure in the reaction chamber;
• and
• increasing the pressure in the secondary chamber;
• increasing a temperature in the reaction chamber;
• and
• processing the substrate by using the supercritical fluid in the reaction chamber.