Substrate processing method

A substrate processing method performed in a substrate processing apparatus having, within a processing vessel, a processing space in which a preset processing is performed by supplying a gas to a substrate;

• and a gas exhaust space communicating with the processing space and having a pressure lower than a pressure of the processing space by a preset ratio, the substrate processing method comprising:
• a first process of supplying a first gas to the substrate;
• and
• a second process of supplying a second gas different from the first gas to the substrate after the first process,
• wherein, when a distance from an edge of the substrate to a boundary between the processing space and the gas exhaust space is L, a cross sectional area of a space orthogonal to a flow of the second gas is S(x), a supply flow rate of the second gas is Q, a pressure within the processing space is P and a diffusion coefficient of the first gas with respect to the second gas is D, at least one of the distance L from the edge of the substrate to the boundary between the processing space and the gas exhaust space, the cross sectional area S(x) of the space orthogonal to the flow of the second gas and the supply flow rate Q of the second gas in the second process is adjusted such that a Peclet number Pe calculated by an expression (3) becomes larger than 1
• [
• Expression
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• wherein the method further comprises:
• a third process of supplying a third gas to the substrate after the second process;
• and
• a fourth process of supplying a fourth gas different from the third gas to the substrate after the third process,
• wherein at least one of a distance L from the edge of the substrate to the boundary between the processing space and the gas exhaust space, a cross sectional area S(x) of a space orthogonal to a flow of the fourth gas and a supply flow rate Q of the fourth gas in the fourth process is adjusted such that the Peclet number Pe becomes larger than 1.