Evaluation of InP-to-silicon heterobonding

In this paper, we evaluate hydrophilic (HP) and hydrophobic (KB) surface pr e-treatments in InP-to-Si direct wafer bonding, Surface roughness and surfa ce chemistry was examined using atomic force microscopy and X-ray photoelec tron spectroscopy, respectively. After bonding: the bonded interfaces were evaluated using infrared transmission imaging, bond-strength and current-vo ltage (I-V) measurements. It was found that HP surface treatment using oxyg en plasma makes room temperature bonding of InP and Si very spontaneous, an d results in high bond-strengths already after low-temperature annealing. T his was not observed when using standard oxidising acids as HP surface trea tment before bonding. HE InP and Si surfaces, also, did nut prove to bond s pontaneously at room temperature and the bond-strength started to increase only after annealing at about 400 degreesC. HE bonding and annealing at 400 degreesC was though the best choice regarding the electrical characteristi cs of the bonded InP/Si heterojunction. (C) 2001 Elsevier Science B.V. All rights reserved.