Maybe that is due to the deposition of the etching byproduct, my advice is to clean your chamber. ÔÚÄúµÄÀ´ÐÅÖÐÔø¾Ìáµ½: >From: yuzhul@eden.rutgers.edu >Reply-To: General MEMS discussion>To: mems-talk@memsnet.org >Subject: [mems-talk] what is the problem with our STS ICP? >Date:Thu, 18 Sep 2008 21:22:55 -0400 (EDT) > >Hi, We have a STS ICP, working fine until recently. > > Problem is when using pure gas, such as O2 or CF4 alone, then plasma is > stable. However if using mixed gas, O2+CF4, then plasma unstable. Lower > top coil power helps but etch rate would be much slower compare to before. > > Can someone give a suggestion? Thanks.