IMPACT OF GATE MICROSTRUCTURE ON COMPLEMENTARY METAL-OXIDE-SEMICONDUCTOR TRANSISTOR PERFORMANCE

This letter reports on the impact of gate microstructure on deep-submi cron complementary metal-oxide-semiconductor (CMOS) device performance . Transistors with different gate microstructures (alpha-Si gate vs po ly-Si gate) were fabricated using a 2.5 V sub-0.25 mu m CMOS process a nd their performances were compared. The alpha-Si gate provides better capability for suppressing boron penetration in p-channel metal-oxide -semiconductor field-effect transistors (MOSFET's), but the depletion effect is more severe than that of the poly-Si gate. A modified gate d oping (MGD) effect, in which the difference of linear transconductance (g(m)) between transistors with two different gate microstructures sh ows a strong gate-length dependence, is reported for the first, time a nd evaluated by the impact of grain boundary segregation on the electr ically activated gate impurity density. The MGD effect makes the poly- Si gate more advantageous in the design of high-performance CMOS trans istors with gate critical lengths shorter than 0.25 mu m.