Method of manufacturing semiconductor device, substrate processing apparatus and non-transitory computer-readable recording medium

A method of processing a substrate, comprising:

• (A) modifying a surface of the substrate into an impurity-containing layer by performing:
• (a) supplying an impurity-containing gas containing an impurity and a dilution gas into a process chamber in which the substrate is accommodated;
• (b) plasma-exciting the impurity-containing gas and the dilution gas;
• and
• (c) supplying an active species containing an impurity generated by plasma-exciting the impurity-containing gas and the dilution gas to the substrate;
• and
• (B) modifying a surface of the impurity-containing layer into an oxide layer after the impurity-containing layer is formed on the surface of the substrate, by performing:
• (d) plasma-exciting an oxygen-containing gas;
• and
• (e) supplying an active species containing oxygen generated by plasma-exciting the oxygen-containing gas to the surface of the substrate,
• wherein a flow rate ratio of the impurity-containing gas to the dilution gas is controlled in (a) such that a partial pressure of the impurity-containing gas in the process chamber is set to a predetermined partial pressure less than a partial pressure at which the impurity-containing gas forms deposits containing a polymer in the process chamber.