Cooling mechanism with coolant, and treatment device with cooling mechanism

A processing apparatus comprising:

• a processing vessel for containing an object to be processed;
• a showerhead for introducing a process gas into the processing vessel;
• a heater for heating the showerhead to an elevated temperature;
• a main flow line for a cooling liquid, including a cooling passage extending through the showerhead;
• a bypass flow line connected to the main flow line so as to bypass the showerhead;
• and
• a cooling liquid control system controlling a flow of the cooling liquid such that:
• (i) the cooling liquid is caused to flow through only the bypass flow line while the showerhead is being heated to the elevated temperature, and
• (ii) the cooling liquid is caused to flow through both the cooling passage and the bypass flow line while the showerhead is being cooled to a reduced temperature,
• wherein the cooling liquid control system includes:
• an inlet shutoff valve placed between an upstream junction of the main flow line and the bypass flow line, and an inlet side of the cooling passage, in the main flow line;
• an outlet shutoff valve placed between a downstream junction of the main flow line and the bypass flow line, and an outlet side of the cooling passage, in the main flow line;
• a bypass shutoff valve placed in the bypass flow line;
• and
• a valve controller controlling the inlet shutoff valve, the outlet shutoff valve and the bypass shutoff valve.