Semi-Aqueous Stripping Formulation for Metal Substrates
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Solution Overview
Problem
Current methods for removing photoresist and residues from semiconductor substrates often corrode, dull, or chemically alter metal surfaces, and there is a need for a cost-effective cleaning formulation that can address this issue without hydroxylamine-based strippers.
Innovation Solution
A formulation comprising alkanolamine, a water miscible organic co-solvent, a quarternary ammonium compound, and a non-free acid functionality corrosion inhibitor, with a pH greater than 9, is used to remove bulk photoresists and post-etched and post-ashed residues from metal substrates, including aluminum and copper.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wet chemical means are used to remove photoresist from substrate, then photoresist removal is achieved, but the surface of metallic circuitry is corroded, dissolved, and/or dulled
Solution Approach 1:
The patent changes the chemical parameters of the cleaning solution by using a non-aqueous solvent system (glycol ether, ketone, ester) instead of traditional aqueous solutions, and controls the pH to be between 8-10. This parameter change allows effective photoresist removal while preventing metal corrosion that occurs with conventional wet chemical methods
Solution Approach 2:
The patent introduces a corrosion inhibitor as an intermediary substance that mediates between the cleaning formulation and the metallic circuitry. This inhibitor layer protects the metal surfaces from harmful chemical interactions while allowing the formulation to remove photoresist and residues effectively
2Reliability
If hydroxylamine-based strippers are used for photoresist removal, then effective stripping is achieved, but the cost of ownership increases
Solution Approach 1:
The patent replaces expensive hydroxylamine-based strippers with a cost-effective formulation using common, inexpensive solvents such as glycol ethers, ketones, and esters. This substitution maintains stripping effectiveness while significantly reducing material costs and overall cost of ownership
Solution Approach 2:
The patent changes the chemical composition parameters from hydroxylamine-based to a solvent system comprising glycol ether (20-60 wt%), ketone (10-40 wt%), and ester (10-40 wt%), achieving comparable or superior performance at lower cost
3Manufacturing precision
If RIE process is used for pattern transfer, then via, metal line and trench formation is achieved, but residues including re-sputtered oxide material and organic materials remain on substrate
Solution Approach 1:
The patent creates a universal cleaning formulation that performs multiple functions: removing photoresist, eliminating RIE residues (re-sputtered oxide and organic materials), and cleaning ashing byproducts. This multi-functional approach addresses all residue types generated during semiconductor manufacturing in a single process step
Solution Approach 2:
The patent uses a composite solvent system combining glycol ethers, ketones, and esters, along with corrosion inhibitors and surfactants, to create a formulation that can dissolve and remove diverse residue compositions including inorganic oxides and organic materials that result from RIE processing
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 formulation effectively removes residues and contaminants from semiconductor substrates without corroding or dulling the surfaces, offering a lower cost of ownership compared to hydroxylamine strippers and demonstrating improved performance with specific corrosion inhibitors like pyrogallol and t-butylcatechol.
Implementation Method 1
The formulation comprises an alkanolamine, a water miscible organic co-solvent, a quarternary ammonium compound, a non-free acid functionality corrosion inhibitor, and remainder water
Implementation Method 2
The formulation effectively removes residues and contaminants from semiconductor substrates without corroding or dulling the surfaces
Implementation Method 3
a quarternary ammonium compound
Implementation Method 4
a non-free acid functionality corrosion inhibitor
Data Source
AI summary
The present invention relates to semi-aqueous formulations and the method using same, to remove bulk photoresists, post-etched and post-ashed residues, as well as contaminations. The formulation comprises: an alkanolamine, a water miscible organic co-solvent, a quarternary ammonium compound, a non-free acid functionality corrosion inhibitor, and remainder water. The pH is greater than 9.