CMOS device with metal gate and method of forming same

Abstract

One method includes forming a PMOS device. The method includes: forming a gate dielectric layer above the semiconductor substrate and in the PMOS region; forming a first metal-containing layer above the gate dielectric layer and in the PMOS region; A metal-containing layer is processed; and a second metal-containing layer is formed over the first metal-containing layer and in the PMOS region. The second metal-containing layer has a work function lower than the bandgap center work function of silicon. The first metal-containing layer and the second metal-containing layer form a gate of the PMOS device. The invention also provides a CMOS device with a metal gate.

Description

technical field [0001] The present invention relates to a semiconductor device, in particular to a CMOS device and a forming method thereof. Background technique [0002] Metal-oxide-semiconductor (MOS) devices are the basic building blocks in integrated circuits. Existing MOS devices typically have a gate electrode containing polysilicon doped with p-type or n-type impurities using a doping operation such as ion implantation or thermal diffusion. The work function of the gate electrode can be tuned to the band edge of silicon. For n-type metal-oxide-semiconductor (NMOS) devices, the work function can be tuned to be close to the conduction band of silicon. For P-type metal-oxide-semiconductor (PMOS) devices, the work function can be tuned close to the valence band of silicon. The adjustment of the work function of the polysilicon gate electrode can be achieved by selecting suitable impurities. [0003] MOS devices with polysilicon gate electrodes exhibit carrier depletio...

AI Technical Summary

Problems solved by technology

The depletion effect leads to an increase in the effective gate dielectric thickness, making it more difficult to form an inversion layer on the surface of the semiconductor

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