Method of producing composite substrate for surface acoustic wave device
AssigneeShin-Etsu Chemical Co., Ltd.
InventorsShoji Akiyama, Masayuki Tanno, Shozo Shirai
Life of this patent
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Abstract
Provided is a composite substrate for surface acoustic wave device which does not cause peeling of an entire surface of a piezoelectric single crystal film even when heating the film to 400° C. or higher in a step after bonding. The composite substrate is formed by providing a piezoelectric single crystal substrate and a support substrate, forming a film made of an inorganic material on at least one of the piezoelectric single crystal substrate and the support substrate, and joining the piezoelectric single crystal substrate with the support substrate so as to sandwich the film made of the inorganic material.
Claims19
A method of producing a composite substrate for surface acoustic wave device, comprising:
- providing a piezoelectric single crystal substrate and a support substrate;
- forming a film made of inorganic material on at least one of the piezoelectric single crystal substrate and the support substrate;
- and
- joining the piezoelectric single crystal substrate with the support substrate so as to sandwich the film made of the inorganic material;
- wherein
- an uneven structure is formed on at least one of the piezoelectric single crystal substrate and the support substrate,
- the film made of the inorganic material is formed on the uneven structure, and
- a numerical value of roughness RSm/wavelength, which is a ratio of the roughness RSm of the uneven structure to the wavelength when the substrate is used as a surface acoustic wave device, is equal to or more than 0.2 and equal to or less than 7.
Dependencies are inferred from the claim text.