Patent ID: 7037746

Claim:
A method for fabricating a capacitive micromachined ultrasound transducer cell, the method comprising: forming a cavity on a topside of a first substrate, wherein the cavity is defined by a plurality of support posts; disposing a diaphragm on the plurality of support posts to form a composite structure with a top portion having a gap between the lower electrode and the diaphragm, wherein the diaphragm comprises one of a first epitaxial layer or a first polysilicon layer wherein the top portion comprises disposing one of the epitaxial layer or the first polysilicon layer on a second substrate, wherein one of the epitaxial layer or the polysilicon layer and the second substrate are oppositely doped and wherein a doping level in the first epitaxial layer is different than a doping level in the substrate; and disposing a stress reducing material comprises geranium in one of the first epitaxial layer or the first polysilicon layer.