DIBL CONSIDERATIONS OF EXTENDED DRAIN STRUCTURE FOR 0.1 MU-M MOSFETS

The drain-induced-barrier-lowering (DIBL) considerations of the extend ed drain structure were studied using two-dimensional (2-D) device sim ulations in the tenth-micrometer regime. We found that the drain exten sion length must be kept at a minimum in order to reduce the transisto r cell area and to improve the device transconductance, G(m). However, without decreasing the deep source/drain junction depth, the minimum value of which is basically limited by the ability to form a good low resistive silicide contact, charge sharing associated with a small ext ension length deteriorates the short channel behavior of the device, v ia DIBL, even if aggressive scaling of the gate oxide thickness and th e junction depth of the drain extension were used, The solution to thi s dilemma would be elevating the source/drain area by selective epitax y to form a shallow, low resistive silicided junction. We propose here a novel device structure using the elevated silicide-as-a-diffusion-s ource (E-SADS), which improves the DIBL-G(m) tradeoff, eliminates the contact problem, and maintains a minimal cell areal increase.