Patent ID: 7213314

Claim:
A method of forming a surface acoustic wave (SAW) filter device, the method comprising: providing a piezoelectric substrate having a thickness at least twice an acoustic wavelength of a SAW; polishing a surface of the piezoelectric substrate; depositing a silicon oxide film onto the surface of the piezoelectric substrate; polishing an exposed film surface of the silicon oxide film deposited on the piezoelectric substrate; providing a surrogate substrate characterized by an expansion coefficient less than that of the piezoelectric substrate, and a thermal conductivity for facilitating thermal diffusion; polishing one surface of the surrogate substrate; depositing a silicon oxide film onto the one surface of the surrogate substrate; polishing an exposed surface of the silicon oxide film deposited on the surrogate substrate; while at a normal temperature, compressing the exposed film surfaces of the silicon oxide films against each other while providing a force sufficient for bonding the piezoelectric substrate to the surrogate substrate; and forming transducers on an exposed surface of the piezoelectric substrate.