Patent ID: 7915177

Claim:
A method of forming a gate insulation film, comprising: carrying a substrate on whose surface a silicon oxide film of insulation film has been formed into a process vessel; subsequently vacuuming the inside of the process vessel to remove residual oxygen in the process vessel; subsequently heating the substrate; subsequently introducing argon gas into the process vessel, then igniting a plasma by using a plane antenna; subsequently setting pressure in the process vessel lower than pressure for the plasma igniting and a flow rate of the argon gas lower than a flow rate of the argon gas at the time of the plasma igniting; subsequently introducing a process gas of nitrogen gas into the process vessel; and subsequently processing of nitridation to the silicon oxide film by the plasma generated from the process gas of argon gas and nitrogen gas in the process vessel, wherein the oxide film is processed by the plasma nitridation so as to have nitrogen concentration of 1 to 30% in atomic percentage.