Post-CMP Cleaning Liquid for CuO Removal and Re-Oxidation Control
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Solution Overview
Problem
Conventional cleaning solutions for semiconductor chips after chemical mechanical polishing (CMP) are inadequate in removing copper oxide (CuO) and prone to re-oxidation, leading to secondary contamination, reduced reliability of gate oxide layers, and increased circuit impedance due to CuO film formation during waiting times.
Innovation Solution
A post-CMP cleaning solution comprising 5-20 parts of a strong base, 5-30 parts of a weak base, 0.5-3 parts of a cellulose derivative, and 0.5-2 parts of a chitin derivative, which forms a monomolecular adsorbent layer to prevent re-oxidation and remove CuO, using renewable biomass derivatives to avoid petroleum-based additives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If acidic cleaning solution is used to remove CuO, then cleaning effectiveness is improved, but copper substrate corrosion increases
Solution Approach 1:
The patent changes the chemical parameters of the cleaning solution by using alkaline environment (pH 10-13) instead of acidic, and specifically controls the oxidation-reduction potential and composition ratios of different bases to achieve effective CuO removal while protecting copper substrate from corrosion
Solution Approach 2:
The cleaning solution uses a composite formulation containing multiple components including strong base (5-20 parts), weak base (5-30 parts), cellulose derivative (0.5-3 parts), and chitin derivative (0.5-2 parts), where each component contributes different functions to achieve synergistic cleaning effect without substrate damage
2Loss of time
If wafer is left in O2-containing environment during waiting time, then process scheduling flexibility is improved, but re-oxidation of Cu2O occurs
Solution Approach 1:
The cleaning solution applies preliminary protective action by forming a passivation layer on the copper surface during cleaning, which prevents or slows down subsequent re-oxidation of Cu2O to CuO during the waiting period, thereby extending the safe waiting time window
Solution Approach 2:
The cleaning solution creates a chemically inert environment on the copper surface through the formed protective layer, which acts as a barrier against oxygen diffusion and prevents re-oxidation reactions during the waiting time between CMP and deposition processes
3Device complexity
If conventional cleaning solution is used, then cleaning process simplicity is maintained, but secondary contamination occurs
Solution Approach 1:
The patent uses biodegradable natural polymers (cellulose and chitin derivatives) that break down easily and do not leave harmful residues, replacing conventional petroleum-based surfactants and cleaning agents that cause secondary contamination
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 removes CuO, inhibits re-oxidation, and enhances the reliability of semiconductor devices by extending the process window, reducing circuit impedance, and improving electrostatic repulsion of contaminants.
Implementation Method 1
Acidic post-CMP cleaning solutions can dissolve CuO and Cu 2 O on the copper surface, and alkaline post-CMP cleaning solutions for semiconductor chips can selectively dissolve CuO
Implementation Method 2
the chitin derivative generates a monomolecular adsorbent layer on the Cu surface, thereby effectively suppressing re-oxidation of the Cu surface within the waiting time
Implementation Method 3
The cleaning solution provides an alkaline environment, which can improve electrostatic repulsion between particle contaminants and substrates
Data Source
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AI summary
A post-chemical mechanical polishing cleaning solution of semiconductor chips, a preparation method and use thereof are provided. The post-chemical mechanical polishing cleaning solution of semiconductor chips includes, parts by mass: 5-20 parts of a strong base; 5-30 parts of a weak base; 0.5-3 parts of a cellulose derivative; 0.5-2 parts of a chitin derivative; 70-95 parts of ultrapure water. The cellulose derivative is one or more of 2,5-furandicarboxylic acid, levulinic acid, and 5-aminolevulinic acid. The chitin derivative is one or more of chitosan oligosaccharide, carboxymethyl chitosan, N-acetyl glucose, glucosamine, and carboxymethyl glucosamine.