Semiconductor structure and formation method thereof

Abstract

The invention relates to a semiconductor structure and a formation method thereof. The formation method comprises the steps of providing a substrate; forming a gate dielectric layer on the substrate;forming a work function layer on the gate dielectric layer; forming a cap layer on the work function layer, wherein the cap layer comprise a Ti layer; and forming a metal layer on the cap layer, wherein the gate dielectric layer, the work function layer, the cap layer and the metal layer are used for forming a gate structure. According to the invention, the cap layer is formed o the work functionlayer before the metal layer is formed, the cap layer comprises the Ti layer, the metal layer generally contains easily diffused F ions, and the F ion is high in electronegativity and easy to be boundwith a Ti ion to form a titanium-fluorine bond. Correspondingly, the Ti ions can well adsorb the F ions. Therefore, the Ti layer can effectively play a role of preventing diffusion of the F ions, sothat the F ions are avoided from being diffused to the work function layer, and thus influences imposed on a work function value of the work function layer are avoided.

Description

technical field [0001] The invention relates to the field of semiconductors, in particular to a semiconductor structure and a forming method thereof. Background technique [0002] The main semiconductor device of an integrated circuit, especially a very large scale integrated circuit, is a metal-oxide-semiconductor field effect transistor (MOS transistor). With the continuous development of integrated circuit manufacturing technology, the technology nodes of semiconductor devices continue to decrease, and the geometric dimensions of semiconductor devices follow Moore's law. When the size of semiconductor devices is reduced to a certain extent, various secondary effects caused by the physical limits of semiconductor devices appear one after another, and it becomes more and more difficult to scale down the feature size of semiconductor devices. Among them, in the field of semiconductor manufacturing, the most challenging thing is how to solve the problem of large leakage curr...

AI Technical Summary

Problems solved by technology

[0004] Although the introduction of high-k metal gates can improve the electrical performance of semiconductor devices to a certain extent, the electrical performance of semiconductor devices formed by the prior art still needs to be improved.

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