Diagonal MOSFETs characterization for 256M DRAM and beyond

A diagonal MOSFET structure has been designed, fabricated and characterized for 256M DRAM and other general applications. The effective W/L ratio is found to play a very important role in diagonal MOSFET´s characteristics because of its three dimensional current flow pattern. In general, the diagonal MOSFETs have lower drive current but Vt is less sensitive to the scaling in device channel length and width. Our experimental results show that Channel Hot Carrier (CHC) degradation of diagonal MOSFETs is similar to that of conventional MOSFETs, despite the current crowding effect in the diagonal MOSFETs