Titanium Nitride Plasma Etching for Roughness and Rate Uniformity

Solution Overview

Problem

Plasma etching of titanium nitride films faces challenges in achieving uniform etching rates across pattern densities and suppressing surface roughness, with existing methods either resulting in high roughness or significant differences in etching rates depending on the plasma gas composition.

Innovation Solution

An etching method involving a cycle of alternating plasmas generated from chlorine-containing and fluorocarbon-containing gases, and chlorine-containing gases without fluorocarbons, is used to etch titanium nitride films, with specific timing for each cycle step to achieve a partially etched bottom surface with reduced roughness and uniformity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If plasma etching is performed using a processing gas containing chlorine-containing gas and fluorocarbon gas, then the roughness of the bottom surface is suppressed, but the difference in etching rates according to pattern densities becomes large

Engineering Contradiction:

Improvebottom surface roughnessVSAvoidetching rate uniformity

Core Design Contradiction:

Manufacturing precisionVSManufacturing precision

Solution Approach 1:

The etching process is divided into multiple sequential steps using different plasma processing gases. The first step uses chlorine-containing gas and fluorocarbon gas to etch the upper portion with suppressed roughness, while the second step uses chlorine-containing gas without fluorocarbon to etch the lower portion with uniform etching rate across pattern densities. This segmentation allows each step to optimize for its specific function.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the titanium nitride film (upper portion vs. lower portion) are etched with different plasma gas compositions tailored to their specific requirements. The upper portion receives fluorocarbon-containing plasma for roughness control, while the lower portion receives fluorocarbon-free plasma for uniform etching rate, applying local quality optimization to different parts of the same workpiece.

Inventive Principle:

Principle #3Local quality

2Manufacturing precision

If plasma etching is performed using a processing gas containing only chlorine-containing gas without fluorocarbon gas, then the difference in etching rates according to pattern densities is reduced, but the roughness of the bottom surface increases

Engineering Contradiction:

Improveetching rate uniformityVSAvoidbottom surface roughness

Core Design Contradiction:

Manufacturing precisionVSManufacturing precision

Solution Approach 1:

The etching process is divided into multiple sequential steps using different plasma processing gases. The first step uses chlorine-containing gas and fluorocarbon gas to etch the upper portion with suppressed roughness, while the second step uses chlorine-containing gas without fluorocarbon to etch the lower portion with uniform etching rate across pattern densities. This segmentation allows each step to optimize for its specific function.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the titanium nitride film (upper portion vs. lower portion) are etched with different plasma gas compositions tailored to their specific requirements. The upper portion receives fluorocarbon-containing plasma for roughness control, while the lower portion receives fluorocarbon-free plasma for uniform etching rate, applying local quality optimization to different parts of the same workpiece.

Inventive Principle:

Principle #3Local quality

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

The method effectively suppresses the roughness of the bottom surface and reduces differences in etching rates across pattern densities, ensuring a more uniform etching process for titanium nitride films.

Implementation Method 1

etching a titanium nitride film with a first plasma

Methodology Applied

Scientific EffectPlasma etching: Plasma

Implementation Method 2

plasma etching is performed for processing a film of a substrate

Methodology Applied

Scientific EffectPhysical sputtering: Sputtering

Implementation Method 3

etching the titanium nitride film with a second plasma

Methodology Applied

Scientific EffectPlasma etching: Plasma

Implementation Method 4

plasma generated from a gas containing chlorine and fluorocarbon is used in plasma etching for a titanium nitride film

Methodology Applied

Scientific EffectChemical etching: Chemical Bonding

Data Source

PatentUS11842900B2Etching method and plasma processing apparatus

Publication Date: 2023.12.12 TOKYO ELECTRON LTD

AI summary

A disclosed etching method includes (a) etching a titanium nitride film with a first plasma, and (b) etching the titanium nitride film with a second plasma. The first plasma is generated from a first processing gas, and the second plasma is generated from a second processing gas. One of the first processing gas and the second processing gas contains a chlorine-containing gas and a fluorocarbon gas, and the other of the first processing gas and the second processing gas contains a chlorine-containing gas and does not contain a fluorocarbon gas. A repetition of a cycle including the operations (a) and (b) is performed. The repetition of the cycle is stopped in a state where the titanium nitride film is partially etched in a film thickness direction thereof.