Selective TaN Barrier Layer Etching Using Azole Peroxy Chemistry

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

The semiconductor industry faces challenges in selectively removing barrier layers, such as tantalum nitride (TaN), during the fabrication of fully aligned vias (FAVs), particularly when aligning metal interconnects, as existing processes lack effective wet or dry methods for selective removal without affecting underlying structures like copper (Cu), cobalt (Co), ruthenium (Ru), and ultra-low K dielectrics (ULKs).

Innovation Solution

The use of an etching composition comprising compounds like benzotriazole, hydrogen peroxide, alkaline metal hydroxides, and water, along with copper complexants, allows for selective and non-selective removal of TaN barrier layers with respect to Cu, Co, Ru, and ULKs, enabling precise etching by tuning selectivity through concentration variations and pH adjustments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional etching methods are used to remove barrier layers, then the barrier layer can be removed, but the underlying materials (Cu, Co, Ru, ULKs) are also affected and damaged

Engineering Contradiction:

Improveselective removal precisionVSAvoiddamage to underlying materials

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent modifies the chemical parameters of the etching solution by incorporating specific complexing agents (EDTA, ammonia, amines) that change the etching chemistry to be selective for TaN over Cu, Co, Ru, and ULK materials. This parameter change enables precise removal of the barrier layer without damaging underlying structures

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces complexing agents as intermediary substances that mediate between the etchant and the materials being etched. These agents selectively bind to TaN while protecting Cu, Co, Ru, and ULK materials, enabling selective removal without cross-contamination or damage to underlying layers

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of manufacture

If the barrier layer is completely removed, then subsequent processing can proceed, but overlay error and misalignment issues arise in fully aligned via fabrication

Engineering Contradiction:

Improveprocessing continuityVSAvoidvia alignment precision

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent applies partial removal of the barrier layer rather than complete removal. The etching process is controlled to remove only the necessary portion of TaN to enable subsequent processing, while leaving sufficient barrier material to maintain alignment precision and prevent overlay errors in fully aligned via fabrication

Inventive Principle:

Principle #16Partial or excessive action

3Productivity

If existing etching compositions are used, then the etching process can proceed, but selectivity against Cu, Co, Ru, and ULKs is insufficient

Engineering Contradiction:

Improveetching efficiencyVSAvoidmaterial selectivity

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent creates a composite etching solution containing multiple components: hydrogen peroxide (oxidant), acetic acid (pH buffer), and specific complexing agents (EDTA, ammonia, amines). This composite composition provides both high etching efficiency and superior selectivity against Cu, Co, Ru, and ULK materials through synergistic chemical interactions

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

This approach enables selective etching of TaN with respect to Cu and Co, Ru, and ULKs, achieving high selectivity and efficient removal of barrier layers while minimizing impact on underlying materials, thereby improving the fabrication of FAVs and enhancing interconnect reliability.

Implementation Method 1

removing a portion of the barrier layer from each one of the plurality of openings, wherein at least the removal of the portion of the barrier layer is performed using an etchant including: (a) a compound selected from group consisting of -azole, -triazole, and combinations thereof; (b) a compound containing one or more peroxy groups

Methodology Applied

Scientific EffectChemical Etching: Chemical Bonding

Implementation Method 2

Methodology Applied

Scientific EffectpH Adjustment: Electrolyte

Data Source

PatentUS10002831B2Selective and non-selective barrier layer wet removal

Publication Date: 2018.06.19 INTERNATIONAL BUSINESS MACHINE CORPORATION

AI summary

A method for manufacturing a semiconductor device includes forming a dielectric layer on a substrate, forming a plurality of openings in the dielectric layer, conformally depositing a barrier layer on the dielectric layer and on sides and a bottom of each one of the plurality of openings, depositing a contact layer on the barrier layer in each one of the plurality of openings, removing a portion of each contact layer from each one of the plurality of openings, and removing a portion of the barrier layer from each one of the plurality of openings, wherein at least the removal of the portion of the barrier layer is performed using an etchant including: (a) a compound selected from group consisting of -azole, -triazole, and combinations thereof; (b) a compound containing one or more peroxy groups; (c) one or more alkaline metal hydroxides; and (d) water.