Processing routes for direct bonding of silicon to epitaxially textured diamond

• Published in: Diamond and related materials 2003-03, Vol.12 (3), p.257-261
• Main Authors: Wolter, S.D., Yushin, G.N., Prater, J.T., Sitar, Z.
• Format: Article
• Language: English
• Subjects: Applied sciences; Cross-disciplinary physics: materials science; rheology; Electronics; Exact sciences and technology; Fullerenes and related materials; diamonds, graphite; Materials science; Microelectronic fabrication (materials and surfaces technology); Microelectronics: LSI, VLSI, ULSI; integrated circuit fabrication technology; Physics; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Silicon-on-diamond; Silicon-on-insulator; Specific materials; Wafer bonding
• ISSN: 0925-9635; 1879-0062
• DOI: 10.1016/S0925-9635(02)00392-8

Direct bonding of (1 0 0) silicon to epitaxially textured diamond is reported. Fusion of the silicon wafers to the diamond specimens was conducted at high temperature, under an applied stress of 32 MPa in a dedicated ultra-high vacuum bonding apparatus. The highly oriented films were characterized by a RMS surface roughness of ∼150.0 nm (via atomic force microscopy) and discrete crystallites that had formed on the otherwise smooth, (1 0 0)-sheet textured surfaces. Consequently, only partial bonding was observed from 950 to 1150 °C; attempts at silicon-to-diamond fusion at lower temperatures were unsuccessful. The diamond films were also mechanically polished to a RMS surface roughness of ∼5.0 nm. Successful bonding of silicon to these films was observed at fusion temperatures ⩾850 °C using the same processing conditions implemented in the unpolished diamond work. Scanning acoustic microscopy revealed a more uniform interface in these silicon-on-diamond specimens.