Optical interconnect: a back end integration scheme for waveguides and optoelectronic InP components

Abstract

Photonic on CMOS represents the combination of CMOS technology with integrated optics components. It can bring either a new functionality to the electronic circuit or the driving and the amplifying means to the optical components. In the first case, as global interconnections are expected to face severe limitations in the future, optical interconnects could be an alternative to electrical ones. An integration scheme for an optical signal distribution compatible with a Back End Of the Line microelectronic process is presented. Fabrication of the waveguides on top of Integrated Circuits is followed by the molecular bonding of InP dies, needed to perform the optoelectronic components (sources and detectors). Using PECVD silicon nitride or amorphous silicon coupled to PECVD silicon oxide, optical layers and basic components necessary for an optical distribution were developed. Waveguides with low losses (L 3 N 4 , L 2 square dies and are composed of the epitaxial active layers and especially with a sacrificial, etch-stop layer (InGaAs). Molecular bonding of the dies was performed at room temperature and the thickness of the SiO2 bonding layers ranges up to 1μm. After annealing, the dies can support dicing or other mechanical actions with no degradation of the optical properties.