Composite substrate, elastic wave element, and production method for composite substrate
AssigneeNGK Insulators, Ltd.
InventorsYuji HORI, Takahiro YAMADERA
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Abstract
A composite substrate includes a supporting substrate composed of quartz, a piezoelectric material substrate composed of a material selected from the group consisting of lithium niobate, lithium tantalate and lithium niobate-lithium tantalate; and an interface layer along a bonding interface between the supporting substrate and the piezoelectric material substrate. The interface layer has amorphous structure and contains constituent components including silicon, oxygen and at least one of tantalum and niobium. The interface layer has concentrations of hydrogen atoms, nitrogen atoms and fluorine atoms of 1×1018 atoms/cm3 or higher and 5×1021 atoms/cm3 or lower, respectively.
Claims5
A composite substrate comprising:
- a supporting substrate comprising quartz;
- a piezoelectric material substrate comprising a material selected from the group consisting of lithium niobate, lithium tantalate and lithium niobate-lithium tantalate;
- and
- an interface layer along a bonding interface between said supporting substrate and said piezoelectric material substrate, said interface layer having amorphous structure and comprising constituent components including silicon, oxygen and at least one of tantalum and niobium,
- wherein said interface layer has concentrations of hydrogen atoms, nitrogen atoms and fluorine atoms of 1×1018 atoms/cm3 or higher and 5×1021 atoms/cm3 or lower, respectively.
A method of producing a composite substrate comprising a supporting substrate comprising quartz and a piezoelectric material substrate comprising a material selected from the group consisting of lithium niobate, lithium tantalate and lithium niobate-lithium tantalate, said method comprising the steps of;
- irradiating a plasma containing nitrogen gas onto a surface of said supporting substrate to provide generate an activated surface;
- irradiating a plasma containing nitrogen gas onto a surface of said piezoelectric material substrate to provide an activated surface;
- contacting said activated surface of said supporting substrate and said activated surface of said piezoelectric material substrate to obtain a bonded body;
- thinning said piezoelectric material substrate by processing to a thickness of 20 μm or smaller;
- and
- subjecting said bonded body to a thermal treatment at a temperature of 250° C. or higher and 350° C. or lower.
Dependencies are inferred from the claim text.