| 摘要 |
PROBLEM TO BE SOLVED: To obtain a piezoelectric substrate capable of favorably keeping crystallinity of piezoelectric single crystal, readily controlling the thickness and having desired characteristics by joining a single crystal substrate to a piezoelectric single crystal plate having a material different from the substrate by a solid phase reaction. SOLUTION: A sapphire substrate 1 which is a single crystal substrate having 2 inch diameter, 500μm thickness, about 60nm average line roughness and (01-12) orientation is laminated to LiNbO3 single crystal plate which is a piezoelectric single crystal plate having same size as the substrate, about 100nm average line roughness and (10-10) orientation at an ambient temperature under 200g/cm<2> load by loading, e.g. weight to the plate and the substrate and then, the laminate is heat-treated at about 1,100 deg.C for 10hr to join the substrate to the plate. The surface of LiNbO3 single crystal is ground until the thickness becomes about 10μm and the single crystal is planarized until average line roughness becomes about 5μm by CMP derive and LiNbO3 is formed into thin film to provide the objective piezoelectric substrate S1. When the sapphire substrate 1 is joined to the LiNbO3 single crystal plate, an electrode for vibrating surface acoustic wave is formed on the surface of piezoelectric single crystal plate to provide the objective surface acoustic wave derive.
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