TiN Hard Mask Removal Selectivity via Organic Amine Additives

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Solution Overview

Problem

Existing compositions for removing titanium nitride (TiN) hard masks from semiconductor devices lack selectivity between PVD TiN used as a hard mask and CVD TiN used as a liner or adhesion layer, often resulting in unintended etching or loss of the liner/adhesion layer.

Innovation Solution

A composition comprising peroxide, a base, a weak acid, an ammonium salt, a corrosion inhibitor, and long chain organic amine or polyalkylamine, with a pH between 7 to 11.5, is used to selectively remove PVD TiN while minimizing etching of CVD TiN, achieving a selectivity ratio greater than 2.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If existing compositions are used to remove TiN hard masks, then TiN removal is achieved, but CVD TiN liner or adhesion layer is unintentionally etched or lost

Engineering Contradiction:

Improveselectivity between PVD TiN and CVD TiNVSAvoidloss of CVD TiN liner or adhesion layer

Core Design Contradiction:

Manufacturing precisionVSLoss of substance

Solution Approach 1:

The composition modifies chemical parameters by incorporating specific additives (corrosion inhibitors, chelating agents, surfactants) that change the etching behavior to achieve selectivity between PVD TiN and CVD TiN, allowing removal of PVD TiN while preserving CVD TiN

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The composition uses intermediary substances such as corrosion inhibitors and chelating agents that mediate the etching process to differentiate between PVD and CVD TiN, enabling selective removal without damaging the liner or adhesion layer

Inventive Principle:

Principle #24Intermediary (Mediator)

2Manufacturing precision

If existing compositions are used for TiN removal, then hard mask removal is achieved, but copper loss occurs

Engineering Contradiction:

Improvehard mask removal selectivityVSAvoidcopper loss

Core Design Contradiction:

Manufacturing precisionVSLoss of substance

Solution Approach 1:

Corrosion inhibitors act as intermediaries that protect copper from etching while allowing TiN removal to proceed, preventing copper loss during the hard mask removal process

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The composition adjusts chemical parameters through the addition of corrosion inhibitors and chelating agents that modify the etching selectivity to prevent copper dissolution while maintaining TiN removal capability

Inventive Principle:

Principle #35Parameter changes

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 composition effectively removes PVD TiN hard masks while preserving CVD TiN liners, enhancing etch selectivity and preventing copper loss, thereby improving the reliability of semiconductor processing.

Implementation Method 1

A composition comprising peroxide, a base, a weak acid, an ammonium salt, a corrosion inhibitor, and long chain organic amine or polyalkylamine

Methodology Applied

Scientific EffectOxidation: Oxidation

Data Source

PatentUS10711227B2TiN hard mask and etch residue removal

Publication Date: 2020.07.14 VERSUM MATERIALS US LLC

AI summary

Composition, method and system for PVD TiN hard mask removal from 28/20 nm pattern wafers have been disclosed. The composition uses peroxide as oxidizing agent for PVD TiN hard mask removal under slightly basic conditions. The composition comprises bulky or long chain organic amines or polyalkylamine to improve removal/etching selectivity of PVD TiN vs CVD TiN. The composition further comprises long chain organic acids or amines to maintain Co compatibility.