CMOS transistor reliability and performance impacted by gate microstructure

This paper investigate the impact of CMOS (complementary metal-oxide-semiconductor) gate microstructure on the reliability and performance of deep-submicrometer CMOS transistors. The amorphous silicon (α-Si) gate provides better capability for suppression of boron penetration in p⁺ doped gate p-channel MOSFETs, but gate depletion in the α-Si gate is slightly more severe than that of the poly-Si gate. The gate-length-dependent gate-depletion effect, in which the difference in linear g_m between MOSFETs with two different gate microstructures shows a strong L_g-dependence, is reported and interpreted by impurity diffusion along the grain boundary. A gate nitrogen implant as an effective method for suppression of the boron diffusion is also discussed with emphasis on the impact on both device reliability and performance