SUBSTRATE, MANUFACTURING METHOD OF SUBSTRATE, SAW DEVICE, AND DEVICE

摘要

Provided is a substrate that can be made to have a suitable strength with low-cost and that can be bonded firmly to a piezoelectric substrate. The substrate (1), which is for SAW devices, consists of spinel, and the PV value of the difference in level of one of the main faces (1A) of the substrate (1) is 2 nm to 8 nm inclusive. The average roughness (Ra) value of the one of the main faces (1a) of the substrate (1) is preferably 0.01 nm to 3.0 nm inclusive, more preferably 0.01 nm to 0.5 nm inclusive. Also the Young's modulus of the spinel substrate (1), which is for the SAW device (2) or other devices, is preferably 150 GPa to 350 GPa inclusive.