Raw material gas supply apparatus, raw material gas supply method and storage medium

A raw material gas supply method for supplying a raw material gas obtained by vaporizing a solid or liquid raw material in a raw material container along with a carrier gas to a film forming unit for forming a film on a substrate by using a raw material gas supply apparatus including:

• a carrier gas supply line for supplying a carrier gas to the raw material container;
• a bypass channel branched from the carrier gas supply line and connected to the raw material gas supply line while bypassing the raw material container;
• a dilution gas supply line connected to the raw material gas supply line at a downstream side of a connection portion to which the bypass channel is connected, the dilution gas supply line serving to allow a dilution gas to join with the raw material gas;
• a first mass flow controller and a second mass flow controller connected to the carrier gas supply line and the dilution gas supply line, respectively;
• a mass flow meter provided in the raw material gas supply line at a downstream side of a joining portion to which the dilution gas supply line is connected;
• and a switching mechanism configured to selectively allow a carrier gas to flow through an inside of the raw material container or through the bypass channel, the method comprising:
• obtaining an offset value that is a value of (m3−(m1+m2)), m1, m2 and m3 being respective measurement values of the first mass controller, the second mass flow controller and the mass flow meter, by supplying the carrier gas and the dilution gas in a state where the carrier gas flows through the bypass channel;
• obtaining an actual measurement value of a flow rate of the raw material by subtracting the offset value from a value of (m3−(m1+m2)) obtained by supplying the carrier gas and dilution gas in a state where the carrier gas flows through the inside of the raw material container and calculating a difference between a target value of the flow rate of the raw material and the actual measurement value;
• and
• adjusting a set value of the first mass flow controller such that the flow rate of the raw material becomes the target value based on relationship between the difference, increase/decrease in the flow rate of the raw material, and increase/decrease in the flow rate of the carrier gas.