Novel shallow trench isolation process using flowable oxide CVD for sub-100 nm DRAM

We have investigated the characteristics of cell leakage and data retention time when using flowable oxide chemical vapor deposition (CVD) as a shallow trench isolation (STI) process of 1-Gbit DRAM. The trench gap filling capability was increased dramatically by combining high-density plasma (HDP) CVD with flowable oxide CVD. The reduced local stress by flowable oxide in narrow trenches leaded to decrease in junction leakage and gate induced drain leakage (GIDL) current and increase in data retention time of DRAM compared to HDP STI. Therefore, it is concluded that the combination of flowable oxide and HDP oxide is the most promising technology for STI gap filling process of sub-100 nm DRAM technology.