Enhanced performance of vertical double gate MOSFET (VDGM) with oblique rotating implantation (ORI) method

An enhanced performance of vertical double gate MOSFET (VDGM) structure was revealed by adopting the oblique rotating ion implantation (ORI) method. The device structure was simulated based on TCAD tools and verified by good matching data with the published experimental results. With ORI method a symmetrical self-aligned source/drain regions over the silicon pillar and sharp vertical channel profile was observed. With L_g = 50nm, the V_T is 0.96V in double gate and increased to 1.2V in single gate structure. The sub threshold swing, S = 81.9 mV/dec and S = 87.7 mV/dec were obtained for double and single gate devices respectively. Similarly, large I_Dsat = 370μA/μm was observed for double gate compared to single gate device. By scaling the L_g into 50nm, the V_T remains almost the same when the L_g is larger than 80nm. However, it decreases rapidly when scaled down to 50nm. The leakage current increases rapidly when the L_g is scaled down to 100nm and beyond. However, the ratio of I_ON - I_OFF is seen to be increases even with shorter L_g. These results indicates that ORI method is essential for overcoming various SCE as scaling the channel length down to nanometer regime.