Composite substrates and their manufacturing methods, and surface acoustic wave elements

Abstract

A composite substrate is provided that suppresses surface acoustic wave leakage and breakage, and exhibits excellent reliability. According to an embodiment of the present invention, the composite substrate sequentially comprises a piezoelectric layer, a first intermediate layer, a second intermediate layer, and a supporting substrate. The first intermediate layer comprises silicon oxide, and the second intermediate layer comprises silicon oxynitride. The silicon content in the second intermediate layer is 25 atomic% or more, and the nitrogen content in the second intermediate layer is greater than the oxygen content.

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