Hi. It depends on what kind of equipments that you have. If you have thick enough resist for lift off 2um of Ni and compatible deposition equipment for 2um Ni evaporation then lift off method will give you better size control and good vertical side wall profile. Only chemicals you have to deal with is photo resist and its developer and Acetone. If above condition could not be achieved in your case then etching afterward would be more convenient. Cause conventional photo resist could be used as mask for Ni etching. So make relatively smaller hole pattern(smaller than actual hole size 20um) on Photo resist pattern and then chemically wet etch Ni using etchant such as FeCl3. Wet chemical etching of Ni in this case will be isotropic so you have to test and confirm lateral etch rate of Ni to control size of holl diameter. BTW you said that what you are dealing with is membrane of Ni, does that mean Ni will not be attached to any other substrate such as Si 500um thickness wafer? I automatically assumed that you will form 2um thick Ni onto some other substrate cause you describe lift off process. Myung Rae Cho >From Seoul. On Fri Jan 24 17:09:58 2014, 김덕수 wrote: > Hi. > > at first, I want you to understand that I don't know english very well. > > > I want to form center holes on Ni membrane. > > diameter of membrane is 3~400um(thickness 2um) and of center hole is 2~30um. > > I want to form 5 center holes. > > So I thought two methods. > > > 1. Using lift-off process, center holes is formed without etching process. > 2. after deposition Ni thin film, etching process is progressed for forming center holes. > > > I want to know which is more efficient. > _______________________________________________ > Hosted by the MEMS and Nanotechnology Exchange, the country's leading > provider of MEMS and Nanotechnology design and fabrication services. > Visit us at http://www.mems-exchange.org > > Want to advertise to this community? See http://www.memsnet.org > > To unsubscribe: > http://mail.mems-exchange.org/mailman/listinfo/mems-talk _______________________________________________ Hosted by the MEMS and Nanotechnology Exchange, the country's leading provider of MEMS and Nanotechnology design and fabrication services. Visit us at http://www.mems-exchange.org Want to advertise to this community? See http://www.memsnet.org To unsubscribe: http://mail.mems-exchange.org/mailman/listinfo/mems-talk