Appeal No. 2001-1512 10 Application No. 09/273,541 valve 17 is closed and the gas flow rate necessarily corresponds to the leakage rate at the wafer-chuck interface. Turning now to White, we find that the reference is directed to a similar vacuum processing apparatus that includes an electrostatic chuck and a cooling gas flowing in the gap between the wafer and the chuck. However, as also indicated by Appellant (brief, page 18), White introduces a constant flow of cooling gas at the interface between the workpiece (wafer) and the platen (chuck) having a controlled flow rate of approximately 0.25 sccm (col. 5, lines 16-20). White’s constant flow rate of the cooling gas is comparable to Tezuka’s desired flow rate which is indicated by pressure gage 19. We further find that White teaches that the tightness of contact between the wafer and the chuck may be compromised if the wafer is separated from the chuck due to incorrect placement of the wafer or the presence of particles (generated from the process) landing on the chuck (col. 10, lines 20-44). White also indicates that such separation decreases capacitance between the wafer and the electrode on the chuck and causes the current flow to the electrodes of the electrostatic chuck be reduced (id.). Therefore, White keeps the cooling gas flow at a constant level without corresponding the flow rate to the leakage rate from the gap between the wafer andPage: Previous 1 2 3 4 5 6 7 8 9 10 11 12 13 NextLast modified: November 3, 2007