Precise control of gas concentration ratio in process chamber

A new system for controlling gas concentration in a process chamber was dev eloped using a combination of a new flow controller and a gas pumping syste m. The new flow controller does not exhibit overshooting; thus, a stable ga s flow rate can be realized in a process chamber after valve operation. Fur thermore, very rapid gas displacement in the chamber can be realized by com bined gas flow system and pumping system. As a result, it took only 2 s to stabilize chamber pressure and gas composition from purge gas to process ga ses using Fourier transform infrared spectroscopy (Fr-IR) method. It is pos sible to control process parameters such as gas concentration and working p ressure during the entire process using this system.