DC Improvements and Low-Frequency 1/f Noise Characteristics of Complimentary Metal–Oxide–Semiconductor Transistors with a Single n+-Doped Polycrystalline Si/SiGe Gate Stack

Complimentary metal–oxide–semiconductor (CMOS) transistors with polycrystalline Si (poly-Si)/SiGe as the gate material are presented. The SiGe integration using a local CMOS process was developed. It uses a single n+-doped poly-Si0.7Ge0.3 gate instead of single n+- or double-doped poly-Si gate. After deposition, both the poly-Si and SiGe films used as gate layers were doped with phosphorus ions. The threshold, subthreshold, and low-frequency 1/ f noises of poly-Si/SiGe CMOS transistors are reported. Improvements in the performance of the poly-Si/SiGe CMOS transistor compared with the poly-Si gate CMOS transistor are presented, indicating that the presence of Ge in the gate material is beneficial, which agrees with results reported in the literature. The n-channel metal–oxide–semiconductor (n-MOS) transistor characteristics in the diode mode (VGS=VDS) are shown, followed by transconductance (Gm) results. Improvements in the current–voltage (I–V) characteristics are observed when poly-Si/SiGe CMOS transistors are compared with poly-Si gate CMOS transistors. Another key point is the low-frequency 1/ f noise characteristic, which makes the latter transistors promising devices for RF applications.