100 mm wafer-scale InP-based (λ=1.6 μm) epitaxial transfer for hybrid silicon evanescent lasers

Abstract

We report the large epitaxial transfer of 100 mm InP/InGaAs/InP wafers to Silicon-on-insulator (SOI) substrates through a low-temperature (300degC) O2 plasma- assisted wafer bonding process. Efficient vertical outgassing channels (VOCs) are developed to eliminate the fundamental obstacle of interfacial voids in bonding due to intrinsic chemical reactions. Generated gas species of H2O and H2 can quickly diffuse to VOCs, etched through-holes to buried oxide layer (BOX), and absorbed by the BOX layer owing to the open network structure and large gas permeability. The interfacial void density is reduced from 55,000 cm-2 down to 3 cm-2, more than five orders of magnitude reduction for appropriate design of VOCs. Uniform patterning of VOCs leads to a no outgassing "dead zone" across the entire bonding area, and decrease of the thermal mismatch-induced interfacial strain potentially as well, which both result in the wafer scale-independent bonding. The bonding strain is observed through X-ray rocking curve measurement conducted on both of a 2 times 2 cm2 bonded pair and 100 mm wafer-scale bonding sample. A variety of devices have been fabricated using this technique. As one example, hybrid silicon evanescent distributed feedback (DFB) lasers integrated with monitor photodiodes have been fabricated using this bonding technique. These highly single mode lasers may find applications in computer interconnects.