Hybrid wafers based on a “Silicon/PPLN thin film” stack for optical and Radio-Frequency applications

In this paper, we propose new structures based on “Silicon/PPLN thin film” hybrid wafers for nonlinear-optical and Radio-Frequency applications. This stack is obtained by home-made room-temperature bonding and wafer thinning techniques. Two main wafer bonding techniques have been developed on 3 and 4-inch wafers. The Au/Au bonding for RF applications and the Au/Au/SiO₂ bonding for optical applications. The RF component, an acousto-electric resonator, is based on the electrical excitation of a PPLN thin film. The piezoelectric effect of the lithium niobate material is used to excite acoustic waves in the PPLN. The optical device is a second harmonic generation based on a waveguide defined by a ridge in the PPLN thin film. The concept, the fabrication process and the characterizations of these ones are presented in this paper.