Selective Titanium Nitride Etching with Cu/W Compatible Formulation

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Solution Overview

Problem

Current methods for removing titanium nitride and photoresist etch residues in the semiconductor industry face challenges in achieving high selectivity and etch rates without damaging underlying copper, tungsten, and low-k dielectric materials, particularly as device sizes decrease.

Innovation Solution

A composition comprising an oxidizing agent, etchant, corrosion inhibitor, passivating agent, and solvent, optionally with an iodine scavenger, is used to selectively etch titanium nitride and photoresist residues, ensuring compatibility with copper, tungsten, and low-k dielectric layers by minimizing hydrogen peroxide content and incorporating specific agents to enhance selectivity and control etch rates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional wet etching chemistry is used to remove metal hard mask, then the hard mask can be removed, but the underlying copper and low-k dielectric materials are also affected and damaged

Engineering Contradiction:

Improveselectivity of etchingVSAvoiddamage to metal conductor and insulator layers

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent changes the chemical parameters of the etching composition by using a hydrogen peroxide-free formulation with specific oxidizing agents (iodine-containing compounds like iodine, potassium iodide, sodium iodate), etchants (hydrofluoric acid, ammonium fluoride, tetrafluoroboric acid), corrosion inhibitors, and passivating agents. This parameter change achieves high selectivity for titanium nitride removal while preventing damage to copper and low-k dielectric materials, resolving the contradiction between removal effectiveness and layer protection.

Inventive Principle:

Principle #35Parameter changes

2Object-affected harmful factors

If etching process is made more selective to protect underlying layers, then damage to metal and insulator layers is reduced, but the etch rate of the hard mask decreases

Engineering Contradiction:

Improvedamage to metal conductor and insulator layersVSAvoidetch rate of hard mask

Core Design Contradiction:

Object-affected harmful factorsVSProductivity

Solution Approach 1:

The patent optimizes the concentration and combination of chemical agents in the composition to achieve both high etch rate and high selectivity. The hydrogen peroxide-free formulation with controlled amounts of oxidizing agents, etchants, and additives enables rapid titanium nitride removal while maintaining protection of underlying layers, thus resolving the contradiction between productivity and selectivity.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses a composite chemical formulation combining multiple functional agents: oxidizing agents (for titanium nitride oxidation), etchants (for material removal), corrosion inhibitors (for metal layer protection), and passivating agents (for surface protection). This composite approach enables simultaneous achievement of high etch rate and high selectivity by having different components perform different functions within the same composition.

Inventive Principle:

Principle #40Composite materials

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 solution achieves high selectivity for titanium nitride over tungsten and low-k dielectric materials, with etch rates that are effective and controlled, reducing the risk of damage to underlying layers and improving the efficiency of residue removal.

Implementation Method 1

a composition for selectively removing titanium nitride and/or photoresist etch residue material from the surface of a microelectronic device having same thereon, said composition comprising at least one oxidizing agent

Methodology Applied

Scientific EffectOxidation: Oxidation

Implementation Method 2

Methodology Applied

Scientific EffectChemical etching: Chemical Bonding

Data Source

PatentUS10138117B2Aqueous formulations for removing metal hard mask and post-etch residue with Cu/W compatibility

Publication Date: 2018.11.27 ENTEGRIS INC

AI summary

Compositions useful for the selective removal of titanium nitride and/or photoresist etch residue materials relative to metal conducting, e.g., tungsten, and insulating materials from a microelectronic device having same thereon. The removal compositions are low pH and contain at least one oxidizing agent and at least one etchant as well as corrosion inhibitors to minimize metal erosion and passivating agents to protect dielectric materials.