Nitrogen-Free ARC Layer for Low-k Dielectric Integrity
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Solution Overview
Problem
The patterning of low-k dielectric materials in integrated circuits is hindered by resist poisoning due to interactions between nitrogen and photoresists, leading to inaccurate feature formation and increased production costs, especially at advanced lithography wavelengths like 193 nm.
Innovation Solution
A substantially nitrogen-free anti-reflective coating (ARC) layer is formed, which also acts as a capping layer, reducing resist poisoning and providing mechanical stability, thus eliminating the need for a separate capping layer and simplifying the process. This ARC layer is composed of silicon dioxide with carbon, formed using nitrogen-free process gases to minimize contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional ARC layer containing nitrogen is used, then the anti-reflective properties are achieved, but resist poisoning occurs due to nitrogen-photoresist interactions leading to inaccurate feature formation
Solution Approach 1:
The patent extracts and removes nitrogen from the ARC layer composition entirely. The nitrogen-free ARC layer is formed using silicon oxide and silicon oxynitride without any nitrogen-containing compounds, thereby eliminating the source of resist poisoning while maintaining the anti-reflective function.
Solution Approach 2:
The patent changes the chemical composition parameters of the ARC layer by eliminating nitrogen content and adjusting the ratio of silicon oxide to silicon oxynitride. This parameter change transforms the ARC layer from a nitrogen-containing composition to a nitrogen-free composition, resolving the resist poisoning issue.
2Manufacturing precision
If the ARC layer is made nitrogen-free to reduce resist poisoning, then feature formation accuracy improves, but the mechanical stability and etch selectivity may be compromised
Solution Approach 1:
The patent uses a composite material structure consisting of multiple layers: a first ARC layer of silicon oxide and a second ARC layer of silicon oxynitride. This composite structure provides both the nitrogen-free environment needed to prevent resist poisoning and the mechanical stability required for reliable processing.
Solution Approach 2:
The patent applies different material compositions to different layers of the ARC structure. The first ARC layer (silicon oxide) provides nitrogen-free properties, while the second ARC layer (silicon oxynitride) provides enhanced mechanical strength and etch selectivity, with each layer optimized for its specific function.
3Reliability
If multiple separate layers (ARC layer and capping layer) are used, then mechanical stability is ensured, but the process complexity increases
Solution Approach 1:
The patent merges the ARC layer and capping layer functions into a single integrated ARC layer structure. This nitrogen-free ARC layer simultaneously provides anti-reflective properties, mechanical protection, and etch selectivity, eliminating the need for a separate capping layer and reducing process complexity.
Solution Approach 2:
The nitrogen-free ARC layer is designed to perform multiple functions: it provides anti-reflective properties for lithography, mechanical protection for the underlying structure, and etch selectivity for subsequent processing steps. This multi-functional design eliminates the need for separate dedicated layers.
4Reliability
If nitrogen is added to silicon carbide to reduce copper electromigration, then copper reliability improves, but the ARC layer composition becomes contaminated with nitrogen
Solution Approach 1:
The patent removes nitrogen from the ARC layer composition entirely, using only silicon oxide and silicon oxynitride without nitrogen-containing compounds. This extraction of nitrogen prevents contamination while maintaining copper reliability through the nitrogen-free environment.
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 nitrogen-free ARC layer significantly reduces resist poisoning effects, enhances etch selectivity, and maintains mechanical stability, ensuring precise feature formation and reliable copper metallization layers, even at critical dimensions below 100 nm, thereby improving production yield and reducing costs.
Implementation Method 1
resist poisoning due to interactions between nitrogen and photoresists
Implementation Method 2
anti-reflective coating (ARC) layer is formed, which also acts as a capping layer
Implementation Method 3
providing mechanical stability
Implementation Method 4
enhances etch selectivity
Data Source
AI summary
The present invention provides a nitrogen-free ARC/capping layer in a low-k layer stack, which, in particular embodiments, is comprised of carbon-containing silicon dioxide, wherein the optical characteristics are tuned to conform to the 193 nm lithography. Moreover, the ARC/capping layer is directly formed on the low-k material, thereby also preserving the integrity thereof during an etch and chemical mechanical polishing process.