Transfer of AlGaAs/GaAs crystalline Bragg mirror from a GaAs substrate to a fused silica substrate by direct bonding
Résumé
Direct bonding has been a major key technology in many fields nowadays. From microelectronic to optoelectronic technologies, it became a technique used for mass production technology in many different applications. Direct bonding of silicon or silicon dioxide is now a well known process. In this article, we explore this technology through the transfer of III-V AlGaAs/GaAs crystalline multilayer from its native GaAs substrate upon a fused silica substrate (SiO2). The goal of this work is to explore the conception of crystalline Bragg mirrors with low mechanical loss and high optical quality for precision measurement applications.
We present the main results obtained for each step of the transfer process. Various experiment such as AFM characterization have been performed on the wafers to probe surface quality. Chemical wet etching with different experimental conditions have been tested to remove the GaAs substrate. We discuss the main challenges of the process, especially the bonding of two rather different materials from the thermo-mechanic point of view. Focus is also made on the chemistry used in the wet etching part to have a selective etching between GaAs and AlGaAs.
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