Dual Damascene Via Cleaning with Carbon Monoxide Ashing
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Solution Overview
Problem
The dual damascene process in semiconductor fabrication faces challenges with residues left on via holes after etching, which affect critical dimension and performance, and current methods require high-cost solvents for cleaning, increasing processing costs.
Innovation Solution
The method employs carbon monoxide (CO) gas during an ash process to effectively remove residues from via holes, followed by deionized water for cleaning, reducing the need for high-cost solvents and maintaining critical dimension integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fluorine-containing gas (CF4) is used to remove photoresist layer, then photoresist removal efficiency is improved, but fluorine-containing residues remain on via hole sidewall and bottom corner
Solution Approach 1:
The patent changes the chemical composition parameters of the ashing gas from fluorine-containing (CF4) to oxygen-containing gas, fundamentally altering the chemical reaction pathway to eliminate fluorine residue generation while maintaining photoresist removal capability
Solution Approach 2:
The patent replaces expensive fluorine-containing gas with inexpensive oxygen-containing gas, using a readily available and cost-effective alternative that achieves the same photoresist removal function without the harmful byproducts
2Manufacturing precision
If high-cost liquid solvent is used to clean via hole, then residues are effectively removed, but processing cost increases
Solution Approach 1:
The patent replaces expensive liquid solvents with inexpensive deionized water for cleaning via holes, using a readily available and cost-effective alternative that effectively removes residues without the high processing costs associated with specialized solvents
Solution Approach 2:
The patent changes the cleaning medium from chemical liquid solvents to deionized water, fundamentally altering the cleaning mechanism from chemical dissolution to physical rinsing, which is equally effective for residue removal but significantly reduces processing costs
3Productivity
If oxygen is used for ash process, then photoresist layer is removed, but polymer residues break down and newly formed photoresist residues remain on dielectric layer
Solution Approach 1:
The patent modifies the ashing gas composition from pure oxygen to oxygen-containing gas with specific compositional parameters, optimizing the chemical reaction conditions to achieve complete photoresist removal while preventing the formation of new residues on the dielectric layer
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
This approach enhances cleaning efficiency, reduces process costs, and ensures improved performance by effectively removing residues without affecting the silicon nitride etching stop layer, thus lowering overall fabrication expenses.
Implementation Method 1
carbon monoxide (CO) and deionized (DI) water for efficiently cleaning residues in a via hole after an etching process
Implementation Method 2
deionized (DI) water for efficiently cleaning residues in a via hole
Data Source
AI summary
A method for fabricating a dual damascene structure contains providing a substrate having a conductive layer, an etching stop layer, a dielectric layer, and a photoresist layer thereon, performing an etching process to remove a portion of the dielectric layer through a via pattern of the photoresist layer for forming a via structure in the dielectric layer, providing CO-containing gas to perform an ash process, filling GFP materials into the via structure, forming a photoresist layer with a trench pattern on the substrate, etching the dielectric layer through the trench pattern to form a trench structure in the dielectric layer, above the via structure, and removing the etching stop layer exposed in the via structure.