Sumitomo Electric Industries, Limited

Keiichirou Geshi

Masato Hasegawa

Shigeru Nakayama

Ryota Yamaguchi

A ceramic substrate is formed of polycrystalline ceramic and has a supporting main surface. At the supporting main surface of the ceramic substrate, the mean of grain sizes of the polycrystalline ceramic is 0.5 &#x3bc;m or more and less than 15 &#x3bc;m and the standard deviation of the grain sizes is less than 1.5 times the mean.

Layered body, and saw device

A ceramic substrate is formed of polycrystalline ceramic and has a supporting main surface. At the supporting main surface of the ceramic substrate, the mean of grain sizes of the polycrystalline ceramic is 15 &#x3bc;m or more and less than 40 &#x3bc;m and the standard deviation of the grain sizes is less than 1.5 times the mean.

A layered body includes a ceramic substrate formed of a polycrystalline ceramic and having a supporting main surface and a piezoelectric substrate formed of a piezoelectric material and having a bonding main surface that bonds to the supporting main surface through Van der Waals force. The ceramic substrate includes a supporting main surface amorphous layer formed so as to include the supporting main surface. The piezoelectric substrate includes a bonding main surface amorphous layer formed so as to include the bonding main surface. The supporting main surface amorphous layer has a smaller thickness than the bonding main surface amorphous layer.

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Osaka, Japan

Keiichirou Geshi