Saw device manufacturing method

A surface acoustic wave device manufacturing method comprising:

• a piezoelectric ceramic substrate providing step of providing a piezoelectric ceramic substrate having a first surface and a second surface opposite to each other;
• a support substrate providing step of providing a support substrate having a first surface and a second surface opposite to each other, the support substrate having a thermal expansion coefficient lower than that of the piezoelectric ceramic substrate;
• a piezoelectric ceramic substrate polishing step of polishing the first surface of the piezoelectric ceramic substrate to thereby planarize the first surface of the piezoelectric ceramic substrate;
• a support substrate polishing step of polishing the first surface of the support substrate to thereby planarize the first surface of the support substrate;
• a bonding step of bonding the first surface of the piezoelectric ceramic substrate to the first surface of the support substrate after performing the piezoelectric ceramic substrate polishing step and the support substrate polishing step, thereby forming a stacked substrate composed of the piezoelectric ceramic substrate and the support substrate;
• a grinding step of grinding the second surface of the piezoelectric ceramic substrate of the stacked substrate after performing the bonding step, thereby reducing a thickness of the piezoelectric ceramic substrate to a predetermined thickness;
• a vibration diffusion layer forming step of applying a laser beam to the stacked substrate in a condition where a focal point of the laser beam is positioned entirely inside the support substrate at a depth higher in level than a middle of a thickness of the support substrate towards the first surface of the support substrate after performing the grinding step, the laser beam having a transmission wavelength to the support substrate, thereby forming a modified layer as a vibration diffusion layer inside the support substrate at the depth higher in level than the middle towards the first surface of the support substrate, wherein the piezoelectric ceramic substrate faces upwardly during the vibration diffusion layer forming step;
• and
• an electrode forming step of forming an electrode pattern on the second surface of the piezoelectric ceramic substrate of the stacked substrate after performing the vibration diffusion layer forming step.

A surface acoustic wave device manufacturing method comprising:

• a piezoelectric ceramic substrate providing step of providing a piezoelectric ceramic substrate having a first surface and a second surface opposite to each other;
• a support substrate providing step of providing a support substrate having a first surface and a second surface opposite to each other, the support substrate having a thermal expansion coefficient lower than that of the piezoelectric ceramic substrate;
• a piezoelectric ceramic substrate polishing step of polishing the first surface of the piezoelectric ceramic substrate to thereby planarize the first surface of the piezoelectric ceramic substrate;
• a support substrate polishing step of polishing the first surface of the support substrate to thereby planarize the first surface of the support substrate;
• a bonding step of bonding the first surface of the piezoelectric ceramic substrate to the first surface of the support substrate after performing the piezoelectric ceramic substrate polishing step and the support substrate polishing step, thereby forming a stacked substrate composed of the piezoelectric ceramic substrate and the support substrate;
• a grinding step of grinding the second surface of the piezoelectric ceramic substrate of the stacked substrate after performing the bonding step, thereby reducing a thickness of the piezoelectric ceramic substrate to a predetermined thickness;
• a vibration diffusion layer forming step of applying a laser beam to the stacked substrate in a condition where a focal point of the laser beam is positioned entirely inside the piezoelectric ceramic substrate at a depth near the first surface of the piezoelectric ceramic substrate after performing the grinding step, the laser beam having a transmission wavelength to the piezoelectric ceramic substrate, thereby forming a modified layer as a vibration diffusion layer inside the piezoelectric ceramic substrate at the depth near the first surface of the piezoelectric ceramic substrate;
• and
• an electrode forming step of forming an electrode pattern on the second surface of the piezoelectric ceramic substrate of the stacked substrate after performing the vibration diffusion layer forming step.