Simpler than that. HMDS reacts with exposed positive resist. The acid in the exposed resist acts as a catalyst. The HMDS reaction liberates NH3 and CO2 leaving behind a Si(CH3)3 Silicon Tri-methyl. This is a silicon rich layer that can inhibit diffusion into the resist and Thermal flow. If you can use a true silylation unit that diffuses HMDS into the resist. A higher pressure vapor, 200 to 600 Torr instead of 14 Torr there is a deeper more consistent layer. If you can get a true low pressure plasma system then an Oxygen plasma at 5 millitorr will convert the silicon to silicon dioxide and you have a completely impervious barrier. Bill Moffat -----Original Message----- From: mems-talk-bounces@memsnet.org [mailto:mems-talk-bounces@memsnet.org] On Behalf Of basar bolukbas Sent: Thursday, January 29, 2009 10:11 PM To: mems litho Subject: Re: [mems-talk] Double lithography problem with SU1828-TI35ES Hello Bill, Thank you very much for your answer. What you mean you said ''Silylate''. How can i set to Silicon barrier? Do you you mean SiN deposition? If so i can deposite with PECVD-Sputtering.