Cleaning Formulation for Semiconductor Residue Removal
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Solution Overview
Problem
Current cleaning compositions for semiconductor substrates are inadequate in removing post-etch and post-ash residues without damaging metal circuitry or increasing the dielectric constant of low-k dielectric materials, often eroding copper wires and altering the dielectric properties of porous interlayer dielectrics.
Innovation Solution
A cleaning composition comprising 25-80% water, 0.01-5% fluoride ions, 0.01-10% sulfuric acid, 1-50% alkanolamine, and 1-25% organic acid, with a pH of 7-9, which effectively removes residues without significantly etching metals or altering the dielectric constant, specifically designed for use on substrates with cobalt-containing residues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional cleaning compositions are used to remove post-etch and post-ash residues, then residue removal effectiveness is improved, but metal circuitry (copper wires) is eroded and damaged
Solution Approach 1:
The patent changes the chemical parameters of the cleaning composition by using a buffered pH range (7-9) and specific component concentrations ( HF: 0.01-5%, H2SO4: 0.01-10%, alkanolamine: 1-50%, organic acid: 1-25%) to achieve effective residue removal while controlling metal etch rates. This parameter optimization resolves the contradiction between cleaning effectiveness and metal protection.
2Reliability
If aggressive cleaning compositions are used to remove highly adherent residue, then cleaning power is improved, but the dielectric constant of low-k dielectric materials is increased
Solution Approach 1:
The patent optimizes the chemical composition parameters including buffered pH (7-9), fluoride ion concentration (0.01-5%), and specific ratios of cleaning agents to control the interaction with low-k dielectric materials. This ensures sufficient cleaning power while maintaining the dielectric constant stability (increase ≤0.50).
3Reliability
If plasma ashing is used to convert organic residues to volatile species, then organic residue removal is improved, but inorganic residue is left on the substrate
Solution Approach 1:
The patent uses a specifically formulated liquid cleaning composition as an intermediary to remove the inorganic residue left after plasma ashing. The buffered solution with fluoride ions and chelating agents effectively dissolves and removes inorganic residues without damaging the substrate, complementing the plasma ashing process.
4Productivity
If reactive ion etching is used to produce vias through interlayer dielectric, then via formation is improved, but complex residue mixture is deposited on the substrate
Solution Approach 1:
The patent optimizes the cleaning composition parameters including pH buffering (7-9), fluoride ion content (0.01-5%), and surfactant concentrations to effectively dissolve and remove the complex residue mixture containing re-sputtered oxide, polymeric material, and organic resist components deposited during RIE via formation.
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 composition achieves a low metal etch rate and maintains the dielectric constant of low-k dielectric materials, ensuring effective residue removal without damaging the substrate or increasing electrical resistance, making it suitable for complex semiconductor devices.
Implementation Method 1
The cleaning composition comprises water, a source of fluoride ions, sulfuric acid, an alkanolamine, and an organic acid, with a pH of 7-9, designed to remove post-etch and post-ash residues through chemical dissolution
Implementation Method 2
The alkanolamine and organic acid components form chelating agents that bind to metal ions in the residue, facilitating removal of metal-containing deposits without eroding copper wires
Implementation Method 3
The source of fluoride ions reacts with inorganic residue materials through chemical etching to remove highly adherent post-etch and post-ash deposits from the substrate surface
Implementation Method 4
Sulfuric acid in the cleaning composition oxidizes organic residue components from the dry etching process, converting them to species that can be easily removed from the substrate
Implementation Method 5
The alkanolamine and organic acid form a buffered system that maintains pH between 7-9, stabilizing chemical conditions to prevent excessive metal dissolution and alterations to dielectric properties of low-k materials
Data Source
AI summary
A composition and method for removing copper-containing post-etch and/or post-ash residue from patterned microelectronic devices is described. The removal composition includes water, a fluoride ion source, an alkanolamine, sulfuric acid, and an organic acid. The compositions effectively remove the copper and cobalt-containing post-etch residue from the microelectronic device without damaging exposed low-k dielectric and metal interconnect materials.