Semiconductor structure and manufacturing method thereof

Abstract

The invention provides a semiconductor structure and a manufacturing method thereof. The manufacturing method comprises the steps of providing a semiconductor substrate and an epitaxial layer located on the semiconductor substrate; a plurality of main grooves are formed in the epitaxial layer, the bottom surfaces of the main grooves are exposed out of the semiconductor substrate, and the remaining epitaxial layer serves as a plurality of dummy grids; the dummy gate is provided with a top surface and a bottom surface which are opposite to each other, the width of the top surface of the dummy gate is greater than that of the bottom surface, and a contraction part is arranged between the top surface and the bottom surface, so that the subsequently obtained metal gate structure is also in a shape with a wide upper part and a narrow lower part and is provided with the contraction part, and the current control capability of the metal gate structure is improved; the stray capacitance of the metal gate structure is reduced, and the electrical performance of the semiconductor device is further improved. The semiconductor structure provided by the invention comprises the dummy gate or metal gate structure.

Description

technical field [0001] The invention relates to the technical field of semiconductor manufacturing, in particular to a semiconductor structure and a manufacturing method thereof. Background technique [0002] In an advanced manufacturing process, a semiconductor device such as a CMOS (Complementary Metal Oxide Semiconductor, Complementary Metal Oxide Semiconductor) transistor usually includes a metal gate structure. At present, the method for manufacturing a metal gate structure includes: making dummy gates on a semiconductor substrate; filling an isolation dielectric layer between the dummy gates; and replacing the dummy gates with metal gate structures. [0003] When using the existing method to make a dummy gate, the obtained dummy gate usually has a profile with a wide bottom and a narrow top. After replacing the dummy gate with a metal gate structure, the metal gate structure is also wide at the bottom and narrow at the top. The shape of the metal gate structure is not...

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Problems solved by technology

[0003] When using the existing method to make a dummy gate, the obtained dummy gate usually has a profile with a wide bottom and a narrow top. After replacing the dummy gate with a metal gate structure, the metal gate structure is also wide at the bottom and narrow at the top. The shape of the metal gate structure is not conducive to controlling the current close to the semiconductor substrate, which seriously affects the electrical properties of the metal gate structure, which in turn affects the electrical properties of the semiconductor device.

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