Method of forming a surface acoustic wave (SAW) filter device

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.