Photolithography Stripping Solution with Stable Etching

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Solution Overview

Problem

The existing stripping solutions for photolithography used in semiconductor and liquid crystal panel manufacturing face issues with decreased etching rate and composition alteration over time, leading to variations in product performance due to metal film thickness differences, despite maintaining anticorrosion properties.

Innovation Solution

A stripping solution comprising hydrofluoric acid, a basic compound with a specific structure, water, and an N,N-dialkyl fatty acid amide as an organic solvent, which maintains effective stripping and anticorrosion properties without significant changes in etching rate even when continuously used for long periods.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional stripping solutions (hydrofluoric acid with ammonia or 1,8-diazabicyclo[5.4.0]undecene-7) are used, then stripping ability is improved, but metal corrosion progresses and composition alters over time

Engineering Contradiction:

Improvestripping abilityVSAvoidmetal corrosion

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the chemical parameters by selecting a basic compound with pKb of 5.0 or more (weaker base) and controlling its concentration ratio to hydrofluoric acid at 0.01 to 2.0. This parameter adjustment reduces the corrosiveness while maintaining effective stripping ability, resolving the contradiction between stripping performance and metal corrosion prevention

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite chemical system by combining hydrofluoric acid with a basic compound having specific properties (pKb ≥ 5.0) in controlled proportions. This composite formulation achieves synergistic effects where the weaker base protects metal surfaces while hydrofluoric acid provides etching capability, simultaneously addressing both stripping ability and corrosion resistance

Inventive Principle:

Principle #40Composite materials

2Productivity

If stripping solution is cyclically used, then productivity is improved, but etching rate decreases and composition alters

Engineering Contradiction:

Improvecyclic usabilityVSAvoidetching rate consistency

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent employs a basic compound with high pKb value (weaker base) that is more resistant to degradation during cyclic use. This compound maintains solution composition stability over multiple cycles, preventing etching rate variations and enabling consistent productivity across production batches

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

Instead of using a strong base that degrades quickly (conventional approach), the patent inverts the approach by using a weaker base (pKb ≥ 5.0) that remains stable during cyclic use. This inversion of base strength selection resolves the contradiction between cyclic usability and etching rate consistency

Inventive Principle:

Principle #13The other way round (Inversion)

3Reliability

If heating is applied to improve stripping performance, then stripping ability is improved, but composition alteration and metal corrosion worsen

Engineering Contradiction:

Improvestripping performanceVSAvoidsolution composition stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent changes the chemical parameters by selecting a basic compound with high pKb value that exhibits greater thermal stability. This compound maintains solution composition stability even when heated, allowing improved stripping performance without the composition alteration and metal corrosion problems associated with conventional solutions

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 solution effectively strips photoresist and etching residues with consistent anticorrosion performance and stable etching rates, suitable for cyclic use in manufacturing processes, reducing variations in product performance across different production lots.

Implementation Method 1

it has an ability to effectively strip residual materials of a photoresist pattern and etching residual materials

Methodology Applied

Scientific EffectChemical etching: Chemical Bonding

Implementation Method 2

use of hydrofluoric acid and a compound containing ammonia as a counter amine thereof, hydrofluoric acid and a compound containing 1,8-diazabicyclo[5.4.0]undecene-7 as a counter amine thereof

Methodology Applied

Scientific EffectAcid-base reaction: Chemical Bonding

Data Source

PatentEP2930565B1Stripping solution for photolithography and pattern forming process

Publication Date: 2016.11.30 TOKYO OHKA KOGYO CO LTD

AI summary

Provided are a stripping solution for photolithography that can effectively strip away photoresist pattern residues and etching residues, has an excellent anticorrosion property with respect to metals, and can be continuously used for a long time; and a pattern forming process using the stripping solution. The stripping solution for photolithography contains (A) hydrofluoric acid, a (B) basic compound having a specific structure, (C) water, and a (D) organic solvent comprising an N,N-dialkyl fatty acid amide represented by formula (d-1). In formula (d-1), R1d represents an isopropyl group or a 1-hydroxy-1-methylethyl group; and R2d and R3d each independently represent an alkyl group having 1 to 4 carbon atoms.