AVS 46th International Symposium
    Manufacturing Science and Technology Group Monday Sessions
       Session MS-MoA

Paper MS-MoA6
Gas Distribution System Using an Advanced Flow Controller

Monday, October 25, 1999, 3:40 pm, Room 611

Session: Ultra-Clean Society and Contamination Free Manufacturing
Presenter: M. Nagase, Tohoku University, Japan
Authors: M. Nagase, Tohoku University, Japan
O. Nakamura, Tohoku University, Japan
M. Kitano, Tohoku University, Japan
Y. Shirai, Tohoku University, Japan
T. Ohmi, Tohoku University, Japan
Correspondent: Click to Email
In a single wafer treatment, an individual process is carried out within 30-40 sec. And an accurate control of the working pressure and composition ratio of all source-gases in the process chamber through the entire process period is essentially required for establishing high quality processes. We have developed a total gas system combining a distribution system and a pumping system in order to satisfy this requirement and the system evaluated using FT-IR method. The gas distribution system consists of an advanced flow controller(FCS) and an electrically controlled valve(ECV). The FCS is introduced into the principal that the flow rate is directly proportional to the upstream pressure when the upstream pressure of a orifice is two times higher than the downstream pressure. The advanced distribution system using the FCS and the ECV does not observe overshoot phenomena and so stable gas flow rate can be distributed in the chamber after valve operation. However, in the case of combination chamber volume and gas flow rate, it occurred time lag to become stable gas concentration in chamber. To solve this problem, we developed the multi-step flow rate control. Consequentially, the working pressure rises momentarily because more gas distributes than steady state gas flow rate. This problem is solved to control the pumping property by changing the purge gas flow rate which supplying into the drug screw pump with the FCS. Combining the advanced gas distribution system using the FCS and the ECV and the pumping system, we can perfectly control process parameters such as gas composition and the working pressure on the moment.