I love to use ZnO as a sacrificial layer. It can be removed quickly
(within seconds) in any acid-water mixture (e.g. HCl:H2O 1:50 will remove
2um of ZnO within 30 seconds). You can deposit ZnO be sputtering using
either a ZnO target or a Zn target and N2O+Ar.
Of course Zn is not a very favorable material for many semiconductor
applications but it works great for MEMS.


Marco