Patent ID: 7512038

Claim:
A method of manufacturing an ultrasonic transducer, comprising the steps of: (a) patterning a conductive film to form a first electrode; (b) forming a first insulation film covering said first electrode; (c) flattening said first insulation film to expose the surface of said first electrode; (d) forming a second insulation film covering said first electrode and said first insulation film; (e) forming a sacrifice layer overlapping said first electrode on said second insulation film; (f) forming a third insulation film covering said sacrifice layer and said second insulation film; (g) forming a second electrode overlapping said sacrifice layer on said third insulation film; (h) forming an interconnection joined to said second electrode; (i) forming a fourth insulation film covering said second electrode, said interconnection and said third insulation film; (j) forming an opening penetrating said third insulation film and said fourth insulation film to reach said sacrifice layer; (k) forming a hollow part by removing said sacrifice layer using said opening; and (l) filling said opening with a fifth insulation film to seal said hollow part.