Improvement on the Gate Oxide Integrity Caused by the TUB Charges in SOI Technology

Silicon-On-Insulator (SOI) technology is fabricated on substrate with Buried OXide layer (BOX). It offers high performance for noise and power consumption with high device density. This paper describes the journey of understanding and improving the Gate Oxide Integrity (GOI) for SOI technology. Investigation shows a strong influence from the charges within a TUB to the GOI performance. The TUB is a WELL region formed by Deep Trench Isolation (DTI) and the BOX layer. The TUB charges are influenced by the processes in the ONO (Oxide- Nitride-Oxide) process loop. The charges affect the surface bonding which defines the surface wettability and hence the cleaning efficiency. Using O2 plasma treatment to modify the surface bonding is proven to improve the GOI performance.