A high performance and highly reliable dual gate CMOS with gate/n^- overlapped LDD applicable to the cryogenic operation

A dual-gate CMOS structure has been developed which features an overlap LDD (lightly doped drain) NMOS with n⁺ poly gate and a surface channel PMOS with p⁺ poly gate whose source/drain and gate were salicided with low-resistance TiSi₂. The gate/n^- overlapped structure was fabricated by rotational oblique ion implantation. This CMOS structure can realize low-supply-voltage operation due to the small absolute value of threshold voltage without punchthrough. It is demonstrated that, using the overlap LDD NMOS, the circuit speed and the reliability can be improved, compared with the single and the conventional LDD NMOS. The cryogenic operation of the structure is examined.