Threshold-Sensitivity Minimization of Short-Channel MOSFET´s by Computer Simulation

This paper describes an approach to reducing short-channel effects in small-dimension MOSFET´s, with emphasis focused on the geometrical channel structure along a gate. To minimize threshold-voltage sensitivities, the advantage of an inhomogeneous channel structure with a highly doped region near the source is demonstrated through a theoretical analysis and extensive use of a two-dimensional device simulation. This structure, which can be realized through DSA technology, obtains adequate tolerances for both the channel length and applied drain voltage in the 1-μm channel-length MOSFET; the anticipated channel-length tolerance (Delta L) for maintaining the threshold-voltage fluctuation to within ±10 percent is estimated to be ±0.25 μm when V_d = 5.0 V and gate-oxide thickness t_ox = 30 nm. With this tolerance, threshold sensitivity to drain voltage drops to one-third in a conventional MOSFET. In a 0.5-μm channel-length MOSFET, Delta L is estimated to be ±0.7 μm when V_d = 3.0 V.