Thinning technology for lithium niobate wafer by surface activated bonding and chemical mechanical polishing

Abstract

A lithium niobate (LiNbO3) hybrid wafer was developed by a combination of wafer bonding and chemical mechanical polishing. In this study, various plasma ambients were applied to activate the surface of LiNbO3 and Si substrate to bond the wafers at room temperature. After the surface activated bonding process, the LiNbO3 substrate was lapped by chemical mechanical polishing. The thickness of the 10cm diameter LiNbO3 substrate can be decreased from 400 to 10 mu m without generating serious cracks. Under the optimum lapping parameters, a 1.5 nm surface roughness of the LiNbO3 film can be obtained.