BCl3 Atomic Layer Etching Selectivity via H2 Plasma Modification

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Solution Overview

Problem

The existing atomic layer etching method using BCl3 gas has a low etching selection ratio between metal oxide and silicon oxide films, making it difficult to selectively remove metal oxide films without damaging the silicon oxide films.

Innovation Solution

The method involves supplying H2 gas and a processing gas containing BCl3 to a process space, applying high-frequency power to generate plasma while stopping H2 gas supply, and using rare gas plasma to activate the adsorbate, thereby increasing the etching selection ratio between different oxide films.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If BCl3 gas is used for atomic layer etching, then etching of metal oxide films can be achieved, but the etching selection ratio between metal oxide and silicon oxide films is low

Engineering Contradiction:

Improveetching selection ratioVSAvoiddifficulty of selective etching

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent introduces H2 gas as a modifier to change the chemical state of BCl3 during the etching process. By controlling the H2/BCl3 gas ratio and plasma conditions, the etching chemistry is modified to achieve higher selectivity between metal oxide and silicon oxide films, resolving the contradiction between achieving etching and maintaining high selection ratio

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

H2 gas acts as an intermediary substance that mediates between BCl3 and the oxide films. The H2 modifies the BCl3 plasma chemistry to create a more selective etching environment that preferentially attacks metal oxide while sparing silicon oxide, thus enabling selective etching without requiring complete process redesign

Inventive Principle:

Principle #24Intermediary (Mediator)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach significantly enhances the etching selection ratio, allowing for precise removal of metal oxide films without excessive etching of silicon oxide films, thereby maintaining pattern integrity.

Implementation Method 1

applying power of a predetermined frequency to the process space while supplying the H2 gas is stopped, to generate plasma in the process space

Methodology Applied

Scientific EffectPlasma: Plasma

Implementation Method 2

applying power of a predetermined frequency to the process space

Methodology Applied

Scientific EffectHigh-frequency power application: Dielectric Heating

Implementation Method 3

etching the target object by generating plasma of a rare gas in the process space to activate the adsorbate

Methodology Applied

Scientific EffectPlasma: Plasma

Implementation Method 4

generating plasma of a rare gas in the process space to activate the adsorbate

Methodology Applied

Scientific EffectIon bombardment: Ion Beam

Implementation Method 5

adsorbing an adsorbate based on a processing gas containing BCl3 gas onto a target object

Methodology Applied

Scientific EffectAdsorption: Adsorption

Data Source

PatentUS10847379B2Etching method and etching apparatus

Publication Date: 2020.11.24 TOKYO ELECTRON LTD

AI summary

An etching method includes: adsorbing an adsorbate based on a processing gas containing BCl3 gas onto a target object, which serves as a to-be-etched object, by: supplying H2 gas and the processing gas to a process space in which the target object is disposed; and applying power of a predetermined frequency to the process space, while supplying the H2 gas is stopped, to generate plasma in the process space; and etching the target object by generating plasma of a rare gas in the process space to activate the adsorbate.