A method for isolating a film from a substrate 50 includes the steps of: providing an N+ layer 52 on the substrate 50; forming an insulation layer 54 onto the N+ doped layer 52; etching a pair of trenches 56, 58 through the insulation layer 52 to thereby form an isolation region 60 of insulation material;...http://www.google.es/patents/US5232866?utm_source=gb-gplus-sharePatente US5232866 - Isolated films using an air dielectric
