Urea-Based Semiconductor Cleaning Formulation for Copper Protection
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Solution Overview
Problem
Current cleaning compositions for semiconductor substrates, such as those containing dimethyl acetamide (DMAC), are toxic and environmentally unfriendly, posing risks to workers and the environment, while prior art solutions like organic sulfonic acid-based and amine-based stripping solutions can erode copper wire, leading to discontinuances in circuitry wiring and increased electrical resistance.
Innovation Solution
Aqueous cleaning compositions comprising a urea derivative, such as 1,1-dimethylurea or 1,3-dimethylurea, in combination with a fluoride source like ammonium fluoride, optionally including a water-miscible organic solvent, buffering agent, and corrosion-inhibitor, to effectively remove residues without damaging metal circuitry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dimethyl acetamide (DMAC) is used as a cleaning agent, then cleaning effectiveness is improved, but toxicity and environmental harm increase
Solution Approach 1:
The patent changes the chemical composition parameters by replacing DMAC with a specific aqueous composition containing urea derivative (20-70 wt%), fluoride source (0.1-5 wt%), and water-miscible organic solvent (10-60 wt%), achieving effective cleaning while reducing toxicity
Solution Approach 2:
The patent creates a composite cleaning composition by combining multiple components (urea derivative, fluoride source, water-miscible organic solvent, buffering agent, corrosion inhibitor) to achieve synergistic cleaning effectiveness while eliminating the toxicity of single-component DMAC solutions
2Reliability
If organic sulfonic acid-based or amine-based stripping solutions are used, then residue removal is improved, but copper wire erosion increases
Solution Approach 1:
The patent changes the chemical nature of the cleaning agent by using urea derivatives instead of aggressive organic sulfonic acids or amines, and controls pH through buffering agents to maintain copper safety while achieving effective residue removal
Solution Approach 2:
The fluoride source acts as an intermediary that enables effective removal of inorganic and polymeric residues through complexation, while the urea derivative and corrosion inhibitor mediate protection of copper wire from erosion
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 urea derivative-based compositions provide excellent cleaning properties, are less toxic, and more environmentally acceptable, effectively removing residues without corroding or dulling metal circuitry, thus preventing discontinuances and electrical resistance increases.
Implementation Method 1
aqueous cleaning compositions comprising a urea derivative... effectively removing residues
Implementation Method 2
a fluoride source like ammonium fluoride, effectively removing residues without damaging metal circuitry
Data Source
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AI summary
An aqueous cleaning composition used to remove unwanted organic and inorganic residues and contaminants from substrates, in particular semiconductor substrates, comprises an alkyl and/or alkylol substituted urea such as, for example, dimethyl urea, and a fluoride ion source.