Semiconductor structures and methods of forming them

Abstract

A semiconductor structure and a method of forming the same are provided, the method comprising: providing a substrate including a first region, a second region and a third region, the first region, the second region and the third region for forming a device of different threshold voltages; forming a high-k gate dielectric layer on the substrate; forming a first work function layer on the high-k gate dielectric layer; forming an amorphous silicon layer on the first work function layer of the third region; performing a nitrogen doping process on the high-k gate dielectric layer in the first region; annealing the substrate so that the amorphous silicon layer and the first work function layer in the third region react to form a second work function layer; removing the remaining amorphous silicon layer. The present invention makes the devices formed in the first region, the second region and the third region have different threshold voltages through the scheme of nitrogen doping the high-kgate dielectric layer in the first region and the scheme of reacting the amorphous silicon layer and the first work function layer in the third region to form the second work function layer.

Description

technical field [0001] The invention relates to the field of semiconductor manufacturing, in particular to a semiconductor structure and a forming method thereof. Background technique [0002] In semiconductor manufacturing, with the development trend of VLSI, the feature size of integrated circuits continues to decrease. In order to accommodate the reduction in feature size, the channel length of MOSFETs has also been shortened accordingly. However, as the channel length of the device is shortened, the distance between the source and the drain of the device is also shortened, so the control ability of the gate to the channel becomes worse, and the gate voltage pinches off the channel. The difficulty is also increasing, making the phenomenon of subthreshold leakage (subthreshold leakage), the so-called short-channel effect (SCE: short-channel effects) more likely to occur. [0003] Therefore, in order to better adapt to the reduction of the feature size, the semiconductor ...

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Problems solved by technology

[0004] However, after the introduction of fin field effect transistors, it is difficult to obtain semiconductor devices with different threshold voltages

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