Copper Salt-Based Stripper Solutions for Semiconductor Metal Conservation
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Solution Overview
Problem
Current stripper solutions for semiconductor devices, particularly those using alkaline compositions, lead to metal loss during the fabrication of sub-micron components due to corrosion, and existing corrosion inhibitors have drawbacks such as residual adhesion, toxicity, and biodegradability issues.
Innovation Solution
A stripper solution containing a copper salt, preferably CuCl or Cu(NO3)2, with a metal conservation factor (MCF) of >0 and ≤1, which reduces metal etch rates and is compatible with existing solutions, can be used to minimize metal loss, and the addition of amines enhances solubility and effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If alkaline stripper solutions are used to remove resist, then resist removal effectiveness is improved, but metal loss through corrosion increases
Solution Approach 1:
Copper salts act as an intermediary substance in the stripper solution that mediates between the alkaline environment and metal surfaces. The copper ions form protective complexes or precipitates on metal surfaces, preventing direct corrosive interaction between the alkaline stripper and metal components while allowing the stripper to maintain its resist-removal functionality.
Solution Approach 2:
The invention changes the chemical composition parameters of the stripper solution by adding copper salts (such as CuCl or Cu(NO3)2) to the alkaline base. This parameter modification transforms the stripper from being purely corrosive to having protective properties, reducing metal etch rates while maintaining resist removal capability through the combined chemical effects.
2Loss of substance
If corrosion inhibitors are added to reduce metal loss, then metal conservation is improved, but residual adhesion and toxicity issues worsen
Solution Approach 1:
The copper salts used in the stripper solution serve as consumable protective agents that can be easily rinsed away with water. Unlike traditional corrosion inhibitors that form persistent protective films, the copper-based system allows for complete removal through simple water rinsing, eliminating residual adhesion problems while maintaining protective function during the stripping process.
Solution Approach 2:
The copper salts in the stripper solution provide self-limiting protection where the copper ions naturally regulate their own deposition and protective effect. The system self-adjusts to prevent over-protection or residual buildup, and the copper compounds are inherently more environmentally benign and biodegradable than traditional corrosion inhibitors.
3Loss of substance
If copper salt concentration is increased to reduce metal etch rate, then metal conservation is improved, but solution effectiveness and solubility worsen
Solution Approach 1:
The invention optimizes the concentration parameter of copper salts in the stripper solution to achieve the minimum effective amount needed for metal protection. By carefully controlling copper salt concentration and adjusting other solution parameters (such as pH, temperature, and composition ratios), the system achieves effective metal conservation without exceeding solubility limits or compromising stripper performance.
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 copper salt-based stripper solution effectively reduces metal etch rates, is easily rinsable, and maintains low toxicity, ensuring minimal metal loss and environmental impact during the semiconductor fabrication process.
Implementation Method 1
A stripper solution containing a copper salt, preferably CuCl or Cu(NO3)2, with a metal conservation factor (MCF) of >0 and ≤1, which reduces metal etch rates
Implementation Method 2
the addition of amines enhances solubility and effectiveness
Data Source
AI summary
Resist stripping agents, useful for fabricating circuits and/or forming electrodes on semiconductor devices for semiconductor integrated circuits with reduced metal etch rates, particularly copper etch rates, are provided with methods for their use. The preferred stripping agents contain low concentrations of a copper salt with or without an added amine to improve solubility of the salt. Further provided are integrated circuit devices and electronic interconnect structures prepared according to these methods.