Low temperature wafer bonding by spin on glass

Abstract

We report the development of a low temperature (∼400 °C) and low pressure (∼0.5 kg/cm2) spin-on-glass (SOG) wafer bonding technique that can bond compound semiconductors and silicon without using chemical-mechanical polishing, surface etching or other intermediate materials in the bonding process. The relation of bonding quality and applied bonding pressure was studied. Cross sectional transmission electron microscopy analysis shows that the bonding interface is smooth, uniform and did not generate dislocations. Using this SOG bonding method, simulated vertical-cavity surface-emitting laser (VCSEL) structures that consist of GaInAs and InP cavities sandwiched by Al–oxide/Si distributed Bragg reflectors (DBRs) were successfully bonded to a silicon substrate with the bonding interface located outside the bottom DBR away from the VCSEL cavity.