Composite substrate
A composite substrate that is obtained by bonding a silicon (Si) wafer having an interstitial oxygen concentration of 2 to 10 ppma to a piezoelectric material substrate as a support substrate, and thinning the piezoelectric material substrate after the bonding.
1 . A composite substrate manufactured by bonding method comprising sequentially order steps of:
preparing a piezoelectric material substrate;
preparing a silicon (Si) wafer having an interstitial oxygen concentration of 2 to 10 parts per million atomic (ppma) as a support substrate;
bonding the piezoelectric material substrate and the silicon wafer; and
thinning the piezoelectric material substrate after the bonding to form the composite substrate,
wherein the preparing further comprises providing an intervening layer on either or both surfaces of the piezoelectric material substrate and the silicon wafer prior to the bonding;
wherein the composite substrate comprises:
the support substrate consisting of the silicon (Si) wafer having the interstitial oxygen concentration of 2 to 10 parts per million atomic (ppma); and
the piezoelectric material substrate provided on the support substrate.
2 . The composite substrate according to claim 1 , wherein the piezoelectric material substrate is a lithium tantalate wafer (LT) substrate or a lithium niobate (LN) substrate.
3 . The composite substrate according to claim 1 , wherein the intervening layer comprises at least one of silicon oxide, silicon nitride, silicon oxynitride (SiON), and amorphous silicon.
4 . The composite substrate according to claim 1 , wherein the intervening layer is thermally oxidized silica.
5 . The composite substrate according to claim 1 , wherein at least one surface of the piezoelectric material substrate and the silicon wafer is non-mirror finished.