| 摘要 |
In a composite substrate 10, a back surface 14b of a piezoelectric substrate 14 and a front surface 12a of a support substrate 12 are bonded to each other with an adhesive layer 16. The adhesive layer 16 includes a swelling portion 16a at an outer peripheral area thereof, and the piezoelectric substrate 14 is bonded to the support substrate 12 in an area excluding the swelling portion 16a. Accordingly, air bubbles do not easily enter between the swelling portion 16a of the adhesive layer 16 and the piezoelectric substrate 14, and separations caused by the air bubbles can be prevented. As a result, the support substrate and the piezoelectric substrate can be reliably bonded to each other with the adhesive layer including the swelling portion in the outer peripheral area thereof. |
