Method for forming shallow trench isolation structure and shallow trench isolation structure

Abstract

The invention discloses a method for forming a shallow trench isolation structure and the shallow trench isolation structure. In the process of forming the shallow trench isolation structure, double-layer hard masking films are adopted, namely that an oxide, such as a silicon oxide film is additionally arranged on an original nitride, such as a silicon nitride film. Because the selection ratio ofetching to the silicon oxide is higher than that of the silicon nitride, the surface of the silicon nitride film can not be damaged in the etching process, and the surface of the silicon nitride filmis still smooth and uniform after being etched. The invention ensures that after CMP, the height difference generated between each active region and each adjacent field oxide region on same Wafer plane is consistent, thereby ensuring a uniform outline of grown multi-crystal silicon and ensuring the performance of an integrated circuit.

Description

technical field [0001] The invention relates to the technical field of semiconductor manufacturing, in particular to a method for forming a shallow trench isolation structure and the shallow trench isolation structure. Background technique [0002] With the rapid development of semiconductor manufacturing technology, the integrated circuit manufacturing process has entered the deep submicron era, and the size of semiconductor devices and the isolation structure for isolating semiconductor devices have also shrunk. At a process node below 0.13us, such as a 65nm or even a 45nm node process, the isolation layer between elements in the active area (AA, Active area) of the semiconductor device is mostly formed by a shallow trench isolation (STI, Shallowtrench isolation) process. [0003] Currently, a hard mask such as a silicon nitride (SiN) film is used in forming the shallow trench isolation structure. Figure 1a ~ Figure 1e It is a simplified cross-sectional schematic diagram ...

AI Technical Summary

Problems solved by technology

Due to the variable height difference in the formation of the STI structure, the polysilicon profile will become uneven, and there will be polysilicon residues after the polysilicon is etched later, and these polysilicon residues will cause short circuits or leaks that damage the STI isolation function. current path, degrading the performance of the integrated circuit, leading to reliability issues and device failure

Images