Gleb Yushin

Study of fusion bonding of diamond to silicon for silicon-on-diamond technology

Diamond films grown on silicon were polished to a root-mean-square roughness of 15 nm and bonded to (100) silicon in a dedicated ultrahigh vacuum bonding chamber. Successful bonding was observed at temperatures as low as 950u200a°C under a uniaxial mechanical stress of 32 MPa. Scanning acoustic microscopy indicated complete bonding at fusion temperatures above 1150u200a°C, and some cracking of the diamond film. Cross section transmission electron microscopy of the same specimens revealed an intermediate layer consisting of silicon, carbon, and oxygen. This layer was approximately 30 nm thick and had an amorphous structure.

Direct fusion bonding of silicon to polycrystalline diamond

Abstract High temperature fusion of silicon to diamond is reported. Polished, randomly oriented diamond films and unpolished (100) highly oriented diamond films were bonded to single-side polished (100) silicon in a dedicated ultrahigh vacuum bonding apparatus. Direct bonding under an applied uniaxial stress of ∼32 MPa was observed at temperatures above 950xa0°C. The bonded interface was examined by scanning acoustic microscopy revealing only partial bonding at fusion temperatures of 950 and 1050xa0°C. In contrast, complete bonding was evidenced at 1150 and 1200xa0°C, although cracking of the diamond films became more prominent at these higher fusion temperatures.

Influence of relative wafer rotation on the electrical properties of the bonded SiC/SiC interface

Atomically clean SiC wafers with a root-mean-square roughness of 2 nm were bonded in ultrahigh vacuum at 20 MPa of applied uniaxial pressure at temperatures as low as 800u200a°C. Electrical measurements showed that azimuthal orientation of the bonded couple significantly influences the electrical character of the junction. A low-resistance ohmic interface can be created by high-temperature fusion of aligned 6H–SiC/6H–SiC wafers.

Processing routes for direct bonding of silicon to epitaxially textured diamond

Abstract Direct bonding of (1xa00xa00) 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, (1xa00xa00)-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.