Patent ID: 8851106

Claim:
A gas supplying apparatus that supplies a gas to a chamber where a process is carried out with respect to a substrate at a process pressure less than an atmospheric pressure, the gas supplying apparatus comprising: a pressure controller that reduces a primary pressure thereby providing a secondary pressure greater than the process pressure and less than the atmospheric pressure in a secondary pipe; a pressure sensor that measures a pressure in the secondary pipe; a first open/close valve provided in the secondary pipe; an open/close valve controller that opens or closes the first open/close valve; a pressure comparator that compares the pressure measured by the pressure sensor in the secondary pipe with a first set pressure that is greater than the process pressure by a predetermined pressure; a controller that outputs a signal to the open/close valve controller thereby closing the first open/close valve, when the pressure comparator determines that the pressure in the secondary pipe is less than the first set pressure; and a flow rate controller connected to the secondary pipe; wherein the first set pressure is greater than the sum of the process pressure and a pressure difference stipulated in a specification of the flow rate controller; and wherein the first set pressure is less than atmospheric pressure.