Studies of defects and buried oxides in SIMOX based SOI materials

A detailed study of detects and buried-oxide interface properties has been made on SOI devices fabricated from SIMOX (separation of implantation of oxygen) wafers implanted by Eaton NV-200 in 1986 and devices built from more recently acquired wafers. The analysis includes C-V and C-t measurements on buried-oxide capacitors, and I-V, C-V, and DLTS measurements on n⁺/p and p ⁺/n diodes fabricated on SIMOX substrates. The old SIMOX wafers received oxygen implants of 1.8 or 2.0×10¹⁸ cm ^-2 and were annealed at 1250°C for 2 h. The oxygen dose for the recent SIMOX wafers was also 1.8×10¹⁸, but it received a 1285°C, 2-h anneal. Improved characteristics are reported for new SIMOX devices and are attributed in part to the higher postimplant annealing temperature used. Another possible reason for the increase in device quality is a reduction in the amount of metallic impurity contamination during oxygen implantation. Therefore, the improved performance and characteristics of the new devices most likely reflect lower densities of oxygen-related defects and metallic impurities