Semiconductor structure and forming method thereof

Abstract

The invention relates to a semiconductor structure and a forming method thereof, and the forming method comprises the steps: providing a base which comprises a substrate, discrete fin parts protrudingout of the substrate, and a pseudo gate structure stretching across the fin parts; forming a first side wall layer on the side walls of the pseudo gate structure; forming source-drain doping layers in the fin parts on the two sides of the pseudo gate structure; forming a dielectric layer covering the source-drain doping layers; forming a second side wall layer with the vertical length smaller than that of the first side wall layer at the top end or the bottom end of the first side wall layer; removing the pseudo gate structure; after removing the pseudo gate structure and forming the second side wall layer, forming a trench in the dielectric layer; and forming a metal gate structure filling the trench. According to the embodiment of the invention, the metal gate structure formed in the trench is of a T-shaped or inverted T-shaped structure, the space of the trench is small, and correspondingly, the size of the metal gate structure is small, so that the capacitance coupling effect between the metal gate structure and the source-drain doping layers and between the metal gate structure and a contact hole plug formed in the later period is reduced, and then the parasitic capacitance in the semiconductor structure is reduced.

Description

technical field [0001] Embodiments of the present invention relate to the field of semiconductor manufacturing, and in particular, to a semiconductor structure and a method for forming the same. Background technique [0002] In semiconductor manufacturing, with the development trend of ultra-large-scale integrated circuits, the feature size of integrated circuits continues to decrease. In order to adapt to smaller feature sizes, metal-oxide-semiconductor field-effect transistors (Metal-Oxide-Semiconductor Field-Effect Transistor , MOSFET) channel length has 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 ability of the gate structure to control the channel becomes worse, and the gate voltage pinches off the channel. The channel becomes more and more difficult, making subthreshold leakage (subthreshold leakage), the so-called short-channel effect (SCE:...

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Problems solved by technology

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 ability of the gate structure to control the channel becomes worse, and the gate voltage pinches off the channel. The difficulty of the channel 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

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