Method of forming contact hole

Abstract

A method of forming contact hole is disclosed, including the steps of: providing a semiconductor substrate having a first dielectric layer, a second dielectric layer and a third dielectric layer formed thereon in this order; forming a first contact hole through the third dielectric layer, the second dielectric layer and the first dielectric layer by using an etching process to expose the semiconductor substrate; removing the third dielectric layer; forming a fourth dielectric layer over the second dielectric layer, the fourth dielectric layer filling the first contact hole; forming a second contact hole through the fourth dielectric layer, the second dielectric layer and the first dielectric layer to expose the semiconductor substrate; and removing the fourth dielectric layer. The method is capable of improving the stability of the contact-hole formation process.

Description

CROSS-REFERENCES TO RELATED APPLICATIONS[0001]This application claims the priority of Chinese patent application number 201210451655.1, filed on Nov. 12, 2012, the entire contents of which are incorporated herein by reference.TECHNICAL FIELD[0002]The present invention relates to semiconductor fabrication, and more particularly, to a method of forming contact hole.BACKGROUND[0003]With the development of the semiconductor fabrication into the 40 nm technology node and below, the reduction in both the size of contact holes and the interval between contact holes has imposed great challenges to the photolithography / etching processes during the formation of contact holes. It has become an important issue to both ensure a good exposure result and prevent a short circuit of the contact holes after etching.[0004]FIGS. 1 to 8 show a method of forming contact hole of the prior art. Reference is first made to FIG. 1 which illustrates a semiconductor substrate 10 on which a first dielectric laye...

AI Technical Summary

Benefits of technology

The present invention provides a method for forming contact holes that addresses the issue of contact hole diameter increase and improves the stability of the contact-hole formation process. The method involves first forming a first contact hole and then overing it with a fourth dielectric layer to protect it during subsequent etching processes. This prevents the influence of repetition processes on the diameter of the first contact hole and enhances the stability of the whole process.

Problems solved by technology

With the development of the semiconductor fabrication into the 40 nm technology node and below, the reduction in both the size of contact holes and the interval between contact holes has imposed great challenges to the photolithography / etching processes during the formation of contact holes.

In such repetition process, the third opening may be damaged and widened during the etching step for removing the second BARC layer 17, which will lead to a too large diameter of the first contact hole that will be formed under the third opening.

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