COMPOSITE SUBSTRATE AND MANUFACTURING METHOD THEREOF

摘要

PROBLEM TO BE SOLVED: To prevent bubbles from being produced in a composite substrate where a piezoelectric substrate and a support substrate are bonded via an adhesive layer.

SOLUTION: (a) A piezoelectric substrate 21 having micro protrusions and recesses formed on the rear surface 11a, and a support substrate 12 having a thermal expansion coefficient smaller than that of the piezoelectric substrate 21 are prepared. (b) A filling layer 23 is formed by coating the rear surface 11a with a filer to fill in the micro protrusions and recesses. (c) Surface of the filling layer 23 is mirror finished so that the arithmetic average roughness Ra becomes smaller than that of the rear surface 11a in (a). (d) Surface 13a of a filling layer 13 and surface of the support substrate 12 are bonded via an adhesive layer 14 to form a composite substrate 20.

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