Wet Etching Chemistry for WdC Hard Mask Selectivity
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Solution Overview
Problem
The scaling down of integrated circuit (IC) feature sizes has increased complexity and challenges in copper-based interconnect structures, particularly due to damage from traditional wet etch/clean chemistry to tungsten-doped carbon (WdC) hard masks, leading to poor metal-filling capabilities and reliability issues.
Innovation Solution
A wet etching chemistry is developed that includes an organic solvent matrix, an Alkali source amine, an inhibitor, and water, without peroxide or chelators, to selectively etch the etch stop layer while minimizing damage to the WdC hard mask and underlying metal layers, improving etching selectivity and reducing by-product accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional wet etch/clean chemistry containing peroxide is used, then etching capability is achieved, but damage to WdC hard mask occurs leading to poor metal-filling capability
Solution Approach 1:
The patent changes the chemical composition parameters of the wet etch/clean chemistry by replacing peroxide-containing formulations with an organic solvent-based system containing specific additives (ammonia, EDTA, HF). This parameter change eliminates the harmful oxidizing effect on WdC hard mask while maintaining effective etching capability through alternative chemical mechanisms.
Solution Approach 2:
The patent introduces organic solvents as intermediary substances that mediate the etching process without causing damage to the WdC hard mask. These organic solvents serve as a bridge between the etching requirement and the protection requirement, enabling selective removal of materials while preserving the hard mask integrity.
2Productivity
If feature size is scaled down to increase functional density, then production efficiency increases, but processing complexity and manufacturing challenges increase
Solution Approach 1:
The patent addresses scaling challenges by changing the chemical parameters of the etching process to work effectively at reduced feature sizes. The organic solvent-based chemistry with controlled additives provides precise etching control necessary for advanced technology nodes, enabling continued scaling while managing processing complexity.
3Manufacturing precision
If peroxide-containing wet etch chemistry is used, then etching performance is achieved, but reliability of IC device decreases due to hard mask damage
Solution Approach 1:
The patent uses organic solvents as intermediary substances that enable etching performance while protecting the hard mask and underlying metal layers. These intermediaries facilitate the etching reaction without the harmful side effects of peroxide, thereby maintaining both manufacturing precision and device reliability.
Solution Approach 2:
The patent employs a disposable organic solvent-based chemistry that performs the etching function effectively without requiring the harsh peroxide components. This approach sacrifices the strong oxidizing power of peroxide in exchange for selective etching capability that preserves critical structures, improving overall process reliability.
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 the reliability of IC devices by maintaining the integrity of the WdC hard mask and metal layers, reducing voids in conductive features and improving the metal-filling capability, thereby increasing the yield and reliability of ICs.
Implementation Method 1
performing a wet etching process by using a wet etching chemistry to extend the opening down to the metal structure
Implementation Method 2
The wet etching chemistry includes an organic solvent matrix, an Alkali source amine, an inhibitor, and water
Data Source
AI summary
A wet etching chemistry to selectively remove a polymer residue on an opening embedded in a low-k dielectric layer and an underlying stop layer in a process of forming an interconnect structure is provided. The wet etching chemistry includes: two type of organic solvents, wherein a concentration of the two type of organic solvents is greater than or equal to 70%; an Alkali source amine, at least comprising a tertiary amine; an inhibitor; and water. In some embodiment, the wet etching chemistry is free of a peroxide to avoid damage to the WdC hard mask.