Semiconductor structure and forming method thereof

Abstract

The invention provides a semiconductor structure and a forming method thereof. The forming method comprises the following steps: before filling a first groove on a pretreatment substrate by using a filling material, forming an auxiliary layer covering the inner surface of the first groove; forming a first filling medium and carrying out back etching, wherein the upper surface of the obtained firstfilling medium is higher than the upper surface of the pretreatment substrate; and then forming a second filling medium and executing a second planarization process. Since the grinding amount of thefirst groove region is greater than that of the surrounding region, the first groove region is not easy to sink after the second planarization process is completed; the process of filling the first groove does not need to adopt a photoresist and an exposure process, so that implementation is convenient, and the cost is lower; and according to the semiconductor structure formed by the forming method, the surface with better flatness can be obtained, so that the quality is higher.

Description

technical field [0001] The invention relates to the technical field of semiconductors, in particular to a semiconductor structure and a forming method thereof. Background technique [0002] In the manufacture of integrated circuits, the method of forming STI (Shallow Trench Isolation, Shallow Trench Isolation) is mostly used for the isolation between individual devices fabricated on the substrate, such as different memory cells and different transistors. A commonly used method for making STI includes the following process: first form a pad oxide layer and a silicon nitride layer on the substrate; then sequentially etch the silicon nitride layer, the pad oxide layer, and the substrate in a selected area to form an isolation trench; Next, an isolation dielectric is deposited on the substrate and CMP (Chemical Mechanical Polishing, chemical mechanical polishing) is performed, so that the isolation dielectric filled in the isolation trench is substantially flush with the upper s...

AI Technical Summary

Problems solved by technology

For example, in a method for forming isolated polysilicon units on a substrate, isolation structures higher than the surface of the substrate are first formed on the substrate, and then an oxide layer is formed on the substrate between the isolation structures and filled with polysilicon, and then using CMP removes the part of the polysilicon material higher than the top surface of the isolation structure, but the surface of the polysilicon obtained after CMP often has depressions and poor flatness, and the existing solutions cannot meet the requirements of high efficiency and economy

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