Showerhead and substrate processing apparatus

A showerhead comprising:

• a shower plate;
• a base member including a gas flow path, the base member fixing the shower plate;
• and
• gas supply members disposed at a gas diffusion space, the gas diffusion space being provided between the shower plate and the base member, the gas supply members being connected to the gas flow path,
• wherein each of the gas supply members includes:
• a circumferential side surface including outlets configured to discharge gas radially, and
• a bottom surface closing one end of the circumferential side surface,
• wherein the gas supply members include:
• one or more first gas supply members arranged in an inner concentric ring, and a plurality of second gas supply members in an outer concentric ring,
• wherein the circumferential side surface of each of the plurality of second gas supply members includes:
• a first surface region that faces an adjacent second gas supply member, the first surface region having no outlet, and
• a second surface region including the outlets that are arranged at regular intervals in a circumferential direction of the circumferential side surface except for the first surface region, and
• wherein the plurality of second gas supply members are arranged such that the gas discharged via the outlets of the second gas supply members generates a rotational flow.