Electromechanical transducer and method of fabricating the same

A method of fabricating an electromechanical transducer comprising the following steps:

• an oxide film forming step of providing a silicon oxide film on a front surface of a silicon semiconductor substrate;
• a step of providing a silicon nitride film on the silicon oxide film;
• a step of forming a piezoresistance element of a polycrystalline silicon film in which an impurity is implanted on the silicon nitride film;
• a step of patterning the polycrystalline silicon film;
• a step of patterning the silicon nitride film;
• a step of providing a resin film on entire surfaces of top portions of the silicon nitride film and the piezoresistance element of the polycrystalline silicon film;
• a first mask step of forming a first mask on a back surface of the silicon semiconductor substrate;
• a first etching step of selectively performing anisotropic etching to the silicon oxide film toward the front surface from the back surface of the silicon semiconductor substrate by using the first mask, and forming a weight part and a frame-shaped support part;
• a step of removing the silicon oxide film;
• a second mask step of forming a second mask on the front surface of the silicon semiconductor substrate;
• a second etching step of selectively etching the resin film by using the second mask, and forming a beam part in a slim piece shape that is supported by the support part and supports the weight part by a stacked film of the patterned silicon nitride film and the resin film;
• and
• a mask removing step of removing the first mask and second mask respectively.