Method used for improving short-channel effect and semiconductor structure

Abstract

The invention provides a method used for improving short-channel effect and a semiconductor structure. The method includes providing a substrate including an NMOS area; forming a gate structure on thesubstrate; forming N region grooves in the substrate and on two sides of the gate structure in the NMOS area; forming at least one N-type bottom doped epitaxial layer and an N-type top doped epitaxial layer in sequence on the side wall and the bottom part of each N region groove; the doping concentration of the N-type top doped epitaxial layers is greater than that of the N-type bottom doped epitaxial layer; when the number of N-type bottom doping epitaxial layers is plural, the doping concentration of the N-type bottom doping epitaxial layers increases gradually during the step of forming the N-type bottom doping epitaxial layers; an N-type doping epitaxial layer is formed by the N-type bottom doping epitaxial layers and the N-type top doped epitaxial layers. According ot the invention,the N-type doping epitaxial layer having gradient concentration is formed, so that the doping concentration at a position adjacent to a device channel region of the N-type doping epitaxial layer is comparatively small, so that the short-channel effect of the device is improved.

Description

technical field [0001] The invention relates to the field of semiconductors, in particular to a method for improving short channel effects and a semiconductor structure. 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 semicon...

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Problems solved by technology

[0004] However, the improvement effect of the existing technology on the short channel effect still needs to be improved

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