Problem stsetch SNF 2009-08-08 15:35:23: bad etch

I used my regular DEEP to etch through the wafer. The wafer came out totally charred. I noticed that the backside pressure fluctrated from 9.80 to 9.96, which is probably due to teflon buildup on the wafer o-ring. But this is not the reason for my bad etch. Something is not right with this machine!