Metal plug and forming method thereof

Abstract

The invention provides a metal plug and a forming method thereof, and the method comprises the steps: forming an insulating dielectric layer on a substrate, the insulating dielectric layer sequentially comprises a first interlayer dielectric layer, a stop layer and a second interlayer dielectric layer from bottom to top, the insulating dielectric layer is internally provided with a filling layer, and the filling layer penetrates through the insulating dielectric layer and is in contact with the substrate, the surface of the insulating dielectric layer is also covered; grinding the filling layer for the first time, and stopping grinding on the second interlayer dielectric layer; grinding the filling layer for the second time to enable the surface of the filling layer to be located between the upper surface of the second interlayer dielectric layer and the upper surface of the stop layer; grinding the second interlayer dielectric layer, and stopping grinding on the stop layer; and the filling layer is ground for the third time and metal contact is formed, so that the surface of the metal contact is located below the lower surface of the stop layer, the polishing sequence is adjusted, one-time over-polishing is divided into two times, the single-time grinding stress is reduced, the stripping risk of the metal contact center is eliminated, and the yield loss is reduced.

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