Substrate processing apparatus and gas supply method

A substrate processing apparatus comprising:

• a hydrogen fluoride gas supply unit which provides hydrogen fluoride gas at a predetermined temperature as a processing gas into a processing chamber;
• a pressure-reducing and heating unit connected to the hydrogen fluoride gas supply unit, configured to decrease a pressure of the hydrogen fluoride gas, and configured to heat the hydrogen fluoride gas after adiabatic expansion to maintain the hydrogen fluoride gas at the predetermined temperature;
• and a hydrogen fluoride gas supply pipe connected between the pressure-reducing and heating unit and the processing chamber;
• wherein said hydrogen fluoride gas supply unit comprises a plurality of gas supply holes for introduction of the hydrogen fluoride gas into the processing chamber, each of said gas supply holes is configured to uniformly supply the hydrogen fluoride gas into the processing chamber and prevent liquefaction of the hydrogen fluoride gas when supplied into the processing chamber, said pressure-reducing and heating unit is disposed on-a upstream from the hydrogen fluoride gas supply pipe through which the hydrogen fluoride gas passes before supplying the processing gas into the processing chamber and performs both a reduction of a pressure of the hydrogen fluoride gas and a heating of the hydrogen fluoride gas such that clusters of molecules of the hydrogen fluoride gas are dissociated before supplying the hydrogen fluoride gas into the processing chamber, wherein said pressure-reducing and heating unit reduces the pressure of the hydrogen fluoride gas from more than atmospheric pressure to less than atmospheric pressure.