Etching Composition for UBM Layer Impurity Removal
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Solution Overview
Problem
The formation of conductive bumps using electroplating solutions without cyano groups leads to impurities like aluminum, titanium, and oxide residues on the under-bump metallurgy (UBM) layer, which cause errors during electrical die sorting (EDS) processes due to attachment to probe tips, resulting in inappropriate electrical signal analysis and reduced productivity from abrasive cleaning processes.
Innovation Solution
An etching composition comprising hydrogen peroxide, an aqueous basic solution, an alcohol compound, and an ethylenediamine-based chelating agent is used to effectively remove impurities from the UBM layer without damaging adjacent layers, forming a protective oxide layer to prevent residue adhesion and reducing the frequency of probe tip cleaning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If an electroplating solution without cyano groups is used to form conductive bumps, then toxic gas generation is reduced and bump density is improved, but impurities remain on the bump surface causing EDS process errors
Solution Approach 1:
The etching composition is divided into multiple functional components: hydrogen peroxide for oxidation, aqueous basic solution for dissolution, alcohol compound for organic residue removal, and ethylenediamine-based chelating agent for metal ion complexation. Each component targets specific impurity types to comprehensively clean the bump surface without compromising the non-cyano electroplating benefits
Solution Approach 2:
The patent specifies precise concentration ranges for each etching composition component (hydrogen peroxide: 1-10%, aqueous basic solution: 1-10%, alcohol compound: 0.1-5%, ethylenediamine-based chelating agent: 1-10%) to optimize the balance between impurity removal efficiency and bump surface integrity, ensuring reliable EDS testing while maintaining the advantages of non-cyano electroplating
2Measurement precision
If cleaning processes are performed to remove impurities from probe tips, then measurement accuracy is improved, but probe tips are damaged and productivity is reduced
Solution Approach 1:
The etching composition is applied to remove impurities from the conductive bump surface before the EDS testing process begins. This preliminary cleaning action prevents impurity transfer to probe tips during testing, eliminating the need for subsequent abrasive cleaning operations and maintaining both measurement accuracy and high productivity
Solution Approach 2:
The patent converts the potential harm of impurity accumulation during EDS testing into a benefit by using the etching composition to proactively remove impurities beforehand. The controlled chemical etching process selectively removes impurities while leaving the bump surface intact, transforming what would be a harmful contamination issue into a controlled cleaning advantage that eliminates probe tip damage
3Reliability
If impurities are present on the conductive bump, then EDS process reliability is reduced, but additional cleaning steps increase process complexity
Solution Approach 1:
The patent combines multiple cleaning functions (oxidation, dissolution, organic residue removal, and metal ion complexation) into a single etching composition formulation. This unified approach integrates what would otherwise require multiple separate cleaning steps into one process, improving EDS reliability while minimizing additional process complexity
Solution Approach 2:
The etching composition is designed with multi-functionality to address various types of impurities simultaneously: hydrogen peroxide for oxidative cleaning, aqueous basic solution for inorganic residue dissolution, alcohol compound for organic contaminant removal, and ethylenediamine-based chelating agent for metal ion complexation. This universal cleaning solution handles diverse impurity types in a single step, enhancing EDS process reliability without significantly increasing process complexity
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 etching composition efficiently removes impurities, reducing contact resistance and improving EDS process reliability by minimizing residue attachment to probe cards, thereby enhancing productivity and accuracy in semiconductor chip testing.
Implementation Method 1
hydrogen peroxide, which may oxidize a surface of the conductive bump and form a protective layer thereon
Implementation Method 2
an ethylenediamine-based chelating agent, which may enhance cleaning properties of the etching composition
Implementation Method 3
an aqueous basic solution... that may dissolve impurities that may remain on the conductive bump
Data Source
AI summary
In an etching composition for an under-bump metallurgy (UBM) layer and a method of forming a bump structure, the etching composition includes about 40% by weight to about 90% by weight of hydrogen peroxide (H2O2), about 1% by weight to about 20% by weight of an aqueous basic solution including ammonium hydroxide (NH4OH) or tetraalkylammonium hydroxide, about 0.01% by weight to about 10% by weight of an alcohol compound, and about 2% by weight to 30% by weight of an ethylenediamine-based chelating agent. The etching composition may effectively etch the UBM layer including titanium or titanium tungsten and remove impurities. A method of forming a bump structure may employ such an etching composition.