Blanket tilt implanted shallow trench isolation (BTI-STI) process for enhanced DRAM retention time characteristics

Blanket tilt implanted shallow trench isolation (BTI-STI) process is proposed and investigated for enhanced retention time characteristics of high density DRAM. It is confirmed that BTI-STI process can improve the tail retention time due to low surface channel doping and no degradation is observed for buried-channel p-MOSFET even at narrow width. The proposed process is useful for realizing future high density DRAM without increase in process complexity.