Gas supply unit, substrate processing apparatus, and supply gas setting method

A substrate processing apparatus, comprising:

• a processing chamber accommodating therein a substrate;
• a plurality of gas supply sources;
• a mixing line for mixing a plurality of gases supplied from the gas supply sources to make a gaseous mixture;
• a multiplicity of branch lines for branching the gaseous mixture to be supplied to a multiplicity of places in the processing chamber;
• and
• an additional gas supply unit for supplying a specified additional gas to a gaseous mixture flowing in at least one branch line.

A supply gas setting method using the gas supply unit which includes:

• a plurality of gas supply sources;
• a mixing line for mixing a plurality of gases supplied from the gas supply sources to make a gaseous mixture;
• a multiplicity of branch lines for branching the gaseous mixture to be supplied to a multiplicity of places in the processing chamber;
• an additional gas supply unit for supplying a specified additional gas to a gaseous mixture flowing in at least one branch line;
• and
• valves and pressure gauges for adjusting gas flow rates in the branch lines, respectively,
• the method comprising the following sequential steps of:
• controlling a pressure ratio of the gaseous mixtures branched into the branch lines to be a specified pressure ratio by adjusting the valves under a condition in which the additional gas is not supplied to said at least one branch line from the additional gas supply unit and, then, fixing opening degrees of the valves of the branch lines to values obtained under the condition;
• and
• supplying an additional gas of a specified flow rate to said at least one branch line from the additional gas supply unit.