Fast atom beam-activated n-Si/n-GaAs wafer bonding with high interfacial transparency and electrical conductivity

• DOI: 10.1063/1.4807905
• Publication Date: 2013-05-29T03:41:36Z
• Authors: S. Essig; O. Moutanabbir; A. Wekkeli; H. Nahme; E. Oliva; A. W. Bett; F. Dimroth
• Keywords: 02 engineering and technology; 0210 nano-technology; 7. Clean energy

Optically transparent, electrically conductive n-Si/n-GaAs direct wafer bonds are achieved by a thorough optimization of surface conditioning using fast atom beams. Bonding at room temperature under high-vacuum conditions is systematically investigated after in situ surface deoxidization using either argon or helium fast atom beams. Using argon, high bond energies of up to 900 mJ/m2 are obtained and further enhanced to achieve bulk strength through rapid annealing at 290 °C, thereby enabling the production of thermally stable and mechanically robust hybrid substrates. Moreover, the interface conductivity is significantly improved by an additional thermal annealing at 400 °C. Although it is anticipated to induce higher quality interfaces, helium treatment yields, however, limited and unstable bonding. This difference is attributed to an important surface nano-texturing that occurs during fast atom beam processing, a phenomenon that is peculiar to helium and absent in argon treatment.