HF vapour etching is isotropic, so etching square 10µm x 10µm holes 10µm deep is not possible. What you would get is at best a 20µm circular hole. I'm currently using this process to release fragile MEMS structures with some success. It should be noted, that the only thing you need is a container of 40% HF and a way to suspend your wafer above it (etch-side down) in a fumehood- I use a PTFE/Teflon cylindrical shell with a slightly smaller internal diameter than my wafer, which any workshop can make. The etch rate is about 200nm/minute. We use 1.5µm AZ resist, but I can't tell you if that's the best solution. It seems OK for 10µm etches though. // Morten Daniel Drysdale wrote: > Hi James, have you considered HF vapour etching? I know it is pretty useful for SiO2 etching though I am unsure how your resist will react to the HF vapour. There are a couple of companies that I know of that deal with this.. One based at Livingston and also within Edinburgh University at their SMC building is MEMSSTAR who do this kind of work. As I say, I am unsure of the reaction that the vapour would have with the HF but its a possibility i guess.