Patent ID: 7469461

Claim:
A method for making a diaphragm unit of a condenser microphone, comprising: forming a spacer-forming groove in a substrate; forming a pattern of liftoff protrusions on the substrate such that the spacer-forming groove is disposed around the liftoff protrusions; forming a liftoff layer on the substrate, the liftoff layer being formed on and contouring along an exposed surface of the substrate and exposed surfaces of the liftoff protrusions such that the liftoff layer is formed into a folding region that covers the liftoff protrusions, and a spacer region that extends from the folding region and that is disposed in the spacer-forming groove; forming an insulator spacer layer on the spacer region of the liftoff layer such that the spacer layer fills the spacer-forming groove; forming an insulator diaphragm film on the liftoff layer, the diaphragm film being formed on and contouring along the folding region of the liftoff layer and an exposed surface of the spacer layer such that the diaphragm film is formed into a folding area that overlaps the folding region of the liftoff layer, and an electrode-forming area that overlaps the spacer region of the liftoff layer; forming a sacrificial layer on the folding area of the diaphragm film; and removing the liftoff layer from the diaphragm film and the substrate so as to separate the diaphragm film from the substrate.