Aqueous Alkaline Cleaning Compositions for Semiconductor Substrates

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Solution Overview

Problem

Aqueous alkaline cleaning compositions used in semiconductor fabrication are prone to rapid discoloration and degradation upon oxygen exposure, leading to loss of cleaning efficacy and erroneous sensor outputs, and fail to effectively remove residues from copper metallization surfaces, causing roughening and contamination issues.

Innovation Solution

The development of aqueous alkaline cleaning compositions comprising thioamino acids, quaternary ammonium hydroxides, chelating/corrosion inhibiting agents, and nonionic surfactants, which are free from organic solvents and metal ion-free silicates, specifically designed to maintain stability and enhance cleaning efficiency, particularly for post-CMP cleaning processes in semiconductor fabrication.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional aqueous alkaline cleaning compositions are used, then cleaning operation is performed, but rapid discoloration and degradation occur upon oxygen exposure leading to loss of cleaning efficacy

Engineering Contradiction:
Improvecleaning efficacyVSAvoidcomposition stability
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent changes the chemical parameters of the cleaning composition by replacing conventional ingredients (ammonium hydroxide, hydrogen peroxide, surfactants) with alternative compositions that have different chemical stability properties, thereby maintaining cleaning efficacy while preventing rapid discoloration and degradation upon oxygen exposure

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent develops single-use pre-moistened towelettes that contain the stable cleaning composition, eliminating the need for reusable cleaning systems that would require maintaining composition stability over time. Each towelette is freshly prepared and used once, then discarded, avoiding the stability issues of stored liquid compositions

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

2Productivity

If conventional cleaning compositions are used, then cleaning operation is performed, but erroneous sensor outputs occur

Engineering Contradiction:
Improvefabrication process efficiencyVSAvoidsensor output accuracy
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The patent employs disposable pre-moistened towelettes that are freshly prepared and used once, eliminating contamination and sensor interference issues associated with reusable cleaning systems and stored compositions. This ensures accurate sensor outputs during fabrication process monitoring

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Reliability

If conventional cleaning compositions are used, then cleaning operation is performed, but residues remain on copper metallization surfaces causing roughening

Engineering Contradiction:
Improvesurface qualityVSAvoidsurface roughening
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent changes the chemical composition parameters by using alternative cleaning agents in the towelettes that are specifically effective at removing residues from copper metallization surfaces without causing roughening, thereby improving surface quality while eliminating harmful effects

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 compositions demonstrate improved stability and cleaning efficacy, preventing surface roughening and contamination, maintaining effectiveness even after prolonged storage and exposure to oxygen, and efficiently removing residues from semiconductor substrates and tools without causing damage.

Implementation Method 1

the copper ion concentration can exceed the maximum solubility of the copper-inhibitor complexes during CMP. Therefore, the copper-inhibitor complexes can precipitate from solution

Methodology Applied
Scientific EffectChelation:

Implementation Method 2

aqueous alkaline cleaning compositions for processing substrates useful for fabricating electrical and optical devices

Methodology Applied
Scientific EffectAlkaline cleaning:

Implementation Method 3

at least one nonionic surfactant (D) selected from the group of alkyloxylated, preferably ethoxylated, sorbitan monocarboxylic acid mono esters

Methodology Applied
Scientific EffectSurfactant action: Surfactant

Implementation Method 4

remove residues from copper metallization surfaces, causing roughening and contamination issues

Methodology Applied
Scientific EffectChemical dissolution:

Data Source

PatentEP2596091B1Aqueous alkaline cleaning compositions and methods of their use
Publication Date: 2019.09.18 BASF SE

AI summary

Aqueous alkaline cleaning composition free from organic solvents and metal ion-free silicates, the said compositions comprising (A) a thioamino acid having at least one primary amino group and at least one mercapto group, (B) a quaternary ammonium hydroxide, (C) a chelating and/or corrosion inhibiting agent selected from the group consisting of aliphatic and cycloaliphatic amines having at least two primary amino groups, and aliphatic and cycloaliphatic amines having at least one hydroxy group, (D) a nonionic surfactant selected from the group of acetylenic alcohols, alkyloxylated acetylenic alcohols and alkyloxylated sorbitan monocarboxylic acid mono esters; the use of the alkaline cleaning composition for the processing of substrates useful for fabricating electrical and optical devices; and a method for processing substrates useful for fabricating electrical and optical devices making use of the said aqueous alkaline cleaning composition.