Patent ID: 8430962

Claim:
A gas supply device for supplying a gas into a processing chamber in which a target substrate is arranged, comprising: a gas introduction member including therein a gas diffusion space, through which the gas is introduced into the processing chamber, the gas diffusion space having a first gas diffusion space positioned at a central region of the gas introduction member, a second as diffusion space positioned outside the first as diffusion space, and a third gas diffusion space positioned outside the second gas diffusion space; a processing gas supply unit configured to supply a processing gas into the gas introduction member, the processing gas being used to process the target substrate; a processing gas supply path, connected to the processing gas supply unit, through which the processing gas flows from the processing gas supply unit; branch paths branched off from the processing gas supply path and connected to the gas introduction member, the branch paths having a first branch path configured to supply only the processing gas to the first gas diffusion space and a second branch path configured to supply only the processing gas to the second gas diffusion space; an additional gas supply unit configured to supply an additional gas into the gas introduction member, the additional gas being used to adjust processing characteristics of the processing gas; an additional gas supply path separate from the branch paths, and connected to the additional gas supply unit and the gas introduction member, through which the additional gas flows from the additional gas supply unit to the third gas diffusion space; a branch flow controller having a first flow rate control valve and a first pressure sensor in the first branch path, and having a second flow rate control valve and a second pressure sensor in the second branch path; a bypass passage configured to connect the second branch path to the additional gas supply path; and a bypass valve arranged at at least one of the bypass passage and the additional gas supply path, wherein, in a case where the additional gas is introduced into the processing chamber, the bypass valve is configured to disconnect the third gas diffusion space from the bypass passage so that the additional gas is supplied into the third gas diffusion space, and, in a case where the additional gas is not introduced into the processing chamber, the bypass valve is configured to disconnect the third gas diffusion space from the additional gas supply unit so that the processing gas is supplied into the third gas diffusion space through the bypass passage, and wherein the branch flow controller is configured to control a ratio of a flow rate of the processing gas supplied through the first branch path to that of the processing gas supplied through the second branch path by adjusting an opening degree of each of the first and the second flow rate control valves based on the first and the second pressure sensors.