Film forming method and film forming apparatus

A film forming method for forming a predetermined film, the film forming method comprising:

• providing a film forming apparatus including:
• a processing container configured to accommodate therein a substrate to be processed;
• a gas supply configured to supply a source gas and a reactant gas for forming the predetermined film on the substrate to be processed, carrier gases for carrying the source gas and the reactant gas to the processing container and a purge gas for purging an interior of the processing container, respectively;
• and
• a gas discharge configured to discharge gases in the processing container and maintain a vacuum atmosphere in the processing container,
• wherein the gas supply includes a source gas flow path configured to supply the source gas into the processing container, a reactant gas flow path configured to supply the reactant gas into the processing container, a first carrier gas flow path and a second carrier gas flow path connected to the source gas flow path and the reactant gas flow path, respectively, and configured to supply the carrier gases for the source gas and the reactant gas, a purge gas flow path including a first purge gas flow path connected to the first carrier gas flow path and a second purge gas flow path connected to the second carrier gas flow path, and
• wherein the purge gas flow path is configured to supply the purge gas for purging the interior of the processing container into the processing container by controlling a flow rate of the purge gas separately from the first carrier gas and the second carrier gas, an additive gas flow path configured to supply an additive gas having a predetermined function to the predetermined film, and opening/closing valves configured to independently open and close the source gas flow path, the reactant gas flow path, the first and second carrier gas flow paths, the purge gas flow path, and the additive gas flow path, respectively;
• a first process of constantly supplying the carrier gases into the processing container through the first carrier gas flow path and the second carrier gas flow path in a state in which the substrate to be processed is disposed in the processing container;
• a second process of causing the source gas to be adsorbed to a surface of the substrate to be processed by supplying the source gas into the processing container through the source gas flow path;
• a third process of purging the source gas by stopping the supply of the source gas and supplying the purge gas into the processing container through the purge gas flow path;
• a fourth process of causing the source gas and the reactant gas to react with each other by supplying the reactant gas into the processing container through the reactant gas flow path;
• and,
• a fifth process of purging the reactant gas by stopping the supply of the reactant gas and supplying the purge gas into the processing container through the purge gas flow path,
• wherein the purge gas is supplied into the processing container through the first and second purge gas flow paths at a flow rate which is higher than the flow rate of the first carrier gas and the second carrier gas, while not increasing the flow rate of the first and second carrier gases,
• wherein the second to fifth processes are performed in a predetermined cycle, and
• wherein the additive gas having the predetermined function is supplied through the additive gas flow path as at least a part of the purge gas in one or both of the third process of purging the source gas and the fifth process of purging the reactant gas.