Dear colleagues: I want to construct a silicon nitride microbridge above the Si substrate. Polyimide is used to be the sacrificial layer. I have two groups of questions below: 1)Is PECVD or RF magnetron sputtering(not reactive sputtering) Si3N4 suitful for constructure layer of microbridge? How to lessen the stress of the film during the process? 2)When pattern polyimide, how to dry-etch polyimide and control the angle of the side wall in the process? Is dry-etching better than wet-etching using alkaline reagent? When I wet-etch polyimide, there always have a protrusive ring around the rim of the patterned hole, any one can tell me how to prevent it? How to release polyimide after the bridge has been patterned? Any information will be sincerely appreciated. Thank you all in advance. -- Ma Bin 500, Yu Tian Road Shanghai Institute of Technical Physics The Chinese Academy of Sciences Shanghai 200083 P.R.C. Email: mabin@online.sh.cn Tel: 86-021-65420850-13323(13127)