Re: Problem stsetch SNF 2008-01-16 00:22:49: still observe plasma cutout

Plasma is suppose to cutout if the total He flow is > than 4 sccm. Up until about 2 years ago, the backside He leak interlock had been bypassed. Since then, users have lowered the He pressure setting in order to stay below 4 sccm flow. This practice compromises the wafer because the backside pressure has a larger effect on cooling than does the flow. Now that I have properly adjusted the He dump valve flow, we can now reliably set the backside pressure to 9 Torr without tripping the 4 sccm interlock. Unless the user's wafer is damaged or porous.