Thermal Characteristics of InP-Al2O3/Si Low Temperature Heterogeneous Direct Bonding for Photonic Device Integration

Abstract

Thermal characteristics of InP-Al2O3/Si bonding for photonic integrated circuits application have been reported in this work. This paper firstly demonstrates low temperature heterogeneous direct bonding assisted by a thin layer of high-κ dielectric material (Al2O3). The InP samples with epitaxial growth layer are bonded to a thin Al2O3 layer coated Si wafer at 250°C under a bonding pressure of 3 MPa for 10 hours in vacuum (∼2.5 × 10−4 mbar) ambient. Focused ion beam (FIB) results show an excellent bonding interface and no voids are observed. Compared with samples using SiO2 as the intermediate layer, the simulation results obtained by COMSOL show an outstanding advantage of thermal dissipation using Al2O3 as the intermediate layer. Thermal characterization is accomplished through a Kelvin structure gold (Au) lines on the Al2O3 and SiO2 layer. Due to the excellent thermal conductivity performance of Al2O3, this high quality heterogeneous direct bonding has potential applications for enhancing the performance of Si photonic integrated devices.