Method of plasma-enhanced atomic layer etching

Abstract

A method for etching a layer on a substrate includes at least one etching cycle, wherein an etching cycle includes: continuously providing an inert gas into the reaction space; providing a pulse of an etching gas into the continuous inert gas flow upstream of the reaction space to chemisorb the etching gas in an unexcited state on a surface of the substrate; and providing a pulse of RF power discharge between electrodes to generate a reactive species of the inert gas in the reaction space so that the layer on the substrate is etched.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention generally relates to a method of atomic layer etching (ALE), particularly to a method of plasma-enhanced ALE (PEALE).[0003]2. Description of the Related Art[0004]In order to cope with various processing accompanying microminiaturization and complex structures of semiconductor devices, precision of processing has been remarkably improved by new technology such as double-patterning. However, conventional etching technology such as continuous etching using excited reaction species may be difficult to form fine, narrow convex-concave patterns and may cause defects of shape. Thus, development of etching technology which is capable of performing atomic layer-level etching and is suitable for e.g., double-patterning processes, becomes important. However, low etching rate, poor controllability over directionality of etching, or the like need to be improved.[0005]Any discussion of problems and solutions in ...

AI Technical Summary

Benefits of technology

[0006]Some embodiments provide a method of atomic layer-level etching (referred to as atomic layer etching, ALE) characterized by one or more of the following features: (a) An etching gas is supplied to a reaction space through a mass flow controller, together with an inert gas, wherein the etching gas and the inert gas converge downstream of the mass flow controller, and the inert gas is supplied continuously, whereas the etching gas is supplied in pulses, thereby increasing efficiency of purging; (b) a plasma is used for etching, wherein an inert gas or nitrogen gas is supplied as an essential reactant gas to the reaction space for generating a plasma therein, wherein etching rate is controlled by selectively adding an oxidizing gas such as oxygen gas, or reducing gas such as hydrogen gas as an additional reactant gas; (c) the process temperature is controlled at 0° C. to 250° C.; and (d) directionality of etching is controlled to perform either anisotropic or isotropic etching by selecting the type of reactant gas and etching conditions.

Problems solved by technology

However, conventional etching technology such as continuous etching using excited reaction species may be difficult to form fine, narrow convex-concave patterns and may cause defects of shape.

However, low etching rate, poor controllability over directionality of etching, or the like need to be improved.

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