Mitigation of asymmetrical profile in self aligned patterning etch

摘要

A method which is particularly advantageous for improving a Self-Aligned Pattern (SAP) etching process. In such a process, facets formed on a spacer layer can cause undesirable lateral etching in an underlying layer beneath the spacer layer when the underlying layer is to be etched. This detracts from the desired vertical form of the etch. The etching of the underlying layer is performed in at least two steps, with a passivation layer or protective layer formed between the etch steps, so that sidewalls of the underlying layer that was partially etched during the initial etching are protected. After the protective layer is formed, the etching of the remaining portions of the underlying layer can resume.

主权项

1. A method for self-aligned pattern etching, the method comprising:
providing a substrate having spacers formed on a sidewall of one or more mandrels, wherein the spacers are formed on an underlying layer, and the spacers are formed of a first material, and wherein the underlying layer is formed of a second material; removing the one or more mandrels, such that the resulting spacers have a cross sectional shape in which a first sidewall is relatively planar and a second sidewall, on an opposite side of a respective spacer, is faceted having a non-planar surface; etching a first portion of the underlying layer using the spacers as a mask; depositing or growing a protective layer on sidewalls of the underlying layer created during etching of the first portion; and etching a remaining portion of the underlying layer using the spacers as a mask; wherein the etching of the first portion and the etching of the second portion are performed by plasma etching; wherein etching is stopped during the depositing or growing of the protective layer; wherein during the depositing or growing of the protective layer upon the sidewalls that are formed during the etching of the first portion, the protective layer is also deposited on a bottom wall of the underlying layer, and wherein the method further comprises performing a breakthrough etch to etch through the protective layer on the bottom wall of the underlying layer; and wherein during the breakthrough etch, both:
(a) a plasma gas chemistry is used which is different than a plasma gas chemistry used during etching of the remaining portion of the underlying layer; and(b) a pressure in a processing chamber is reduced compared to a pressure used during the depositing or growing of the protective layer.