A process method for improving the top fillet of double pattern etching mandrel

Abstract

A method for improving that fillet shape of the top of a core mold in a SADP process in a process node of 38nm and below is disclosed. A large core mold film is selecte by two layers of etch, and thatfilm on the top of the core mold is not etched or less etched in the first core mold thinning proces, and the film on the bottom of the core mold is formed with the isotropic characteristics of wet etching, so that the topography of the film on the top of the core mold is large and the bottom is small. After removing the top film layer of the core mold, the isotropic characteristics of wet etching are utilized again in the second core mold thinning process to form the core mold topography perpendicular to the surface, which is beneficial to the subsequent sidewall and etching process, and greatly improves the subsequent double pattern etching process window.

Description

technical field [0001] The invention relates to the field of semiconductor integrated circuit manufacturing, and in particular to a process method for improving the rounded corners at the top of a double pattern etching mandrel. Background technique [0002] As the process nodes of semiconductor manufacturing continue to advance, the critical dimensions continue to shrink, which has exceeded the physical limit of the current mainstream lithography process. In the manufacture of process nodes of 38nm and below, a self-aligned double patterning process (Self-aligned Double Patterning, SADP) is generally used. In the SADP process, in order to facilitate the subsequent etching process, it is required that the side profile of the spacer used as the hard mask should be as vertical as possible to the wafer surface. This requires that the shape of the top of the core mold (core) of the sidewall be as vertical as possible to the surface of the wafer to avoid "rounding" shape (roundi...

AI Technical Summary

Problems solved by technology

Because the wet process has the characteristics of isotropic etching, it will generally lead to rounded corners on the top of the mandrel 10, which will affect the shape of the subsequent side walls 20, and ultimately affect the subsequent critical dimension etching process.

The current technology can only minimize the effect of the rounded corners at the top of the mandrel 10, which is difficult to avoid completely.

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