Tin Etch Composition with Tungsten Inhibitor
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Solution Overview
Problem
Current semiconductor/IC production processes face challenges in tuning the etch rates of titanium nitride (TiN) and tungsten (W) while effectively removing organic and inorganic residues, including those containing fluorine, without damaging the tungsten plug or low-k dielectric materials.
Innovation Solution
A composition comprising aromatic or aliphatic sulfonic acid, inhibitors such as polyethyleneimines or imidazolidinones, an aprotic solvent like dimethyl sulfoxide, a glycol ether, and water, which allows for controlled etching of TiN and W, and the optional use of an oxidant and stabilizer to manage etch rates and residue removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If oxidants such as hydrogen peroxide are added to increase TiN etching rate, then TiN etching rate is improved, but W etching rate also increases undesirably
Solution Approach 1:
A tungsten inhibitor is introduced as an intermediary substance that selectively suppresses the etching of tungsten while allowing TiN etching to proceed. The inhibitor acts as a mediator between the oxidant and the metal surfaces, preventing the oxidant from attacking tungsten plugs while maintaining its effectiveness on TiN layers.
Solution Approach 2:
The composition modifies the chemical parameters of the etching solution by adding specific inhibitors and chelating agents that change the selectivity of the etching process. This allows the same oxidant environment to etch TiN at high rates while protecting tungsten through parameter adjustment in the solution chemistry.
2Productivity
If strong etchants are used to remove organic and inorganic residues, then cleaning efficiency is improved, but damage to low-k dielectric materials increases
Solution Approach 1:
The solution composition is adjusted by adding chelating agents and buffer components that modify the chemical aggressiveness of the etchant. This allows strong etching action on organic and inorganic residues while the chelating agents selectively bind to metals and the buffers control pH, preventing excessive damage to low-k dielectric materials.
Solution Approach 2:
The cleaning composition is formulated as a composite solution containing multiple components including oxidants, chelating agents, buffers, and inhibitors that work synergistically. This composite formulation provides multi-functional action: removing residues effectively while simultaneously protecting sensitive low-k materials through the combined effects of its components.
3Speed
If etch rate of TiN is increased to remove TiN layers, then TiN removal is improved, but selectivity against W and Cu plugs deteriorates
Solution Approach 1:
Metal-specific inhibitors are introduced as intermediary substances that selectively adsorb onto tungsten and copper surfaces, forming protective layers that prevent etching. These inhibitors act as mediators that allow the etchant to selectively attack TiN while being blocked from attacking the metal plugs through the inhibitor layer.
Solution Approach 2:
The etching solution exhibits different local chemical properties at different surfaces due to selective inhibitor adsorption. The inhibitor concentration and binding affinity vary locally at metal surfaces versus TiN surfaces, creating locally different etching rates that achieve high selectivity while maintaining overall high TiN etching speed.
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 controlled etch rate ratio for TiN and W, effectively removing fluorine-containing residues while protecting the tungsten surface and maintaining low etch rates on low-k materials, as demonstrated by experimental results showing enhanced TiN etching rates without increasing W etching rates.
Implementation Method 1
formulations capable of tuning the etch rates of titanium nitride (TiN) and tungsten (W) with the purpose of removing TiN
Implementation Method 2
the presence of oxidants in the formulations, such as hydrogen peroxide, can be necessary to achieve a sufficiently high etching rate of TiN
Implementation Method 3
capable of removing organic and/or inorganic residues (e.g. F-containing) from the wafer surface
Data Source
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AI summary
The present invention relates to a novel composition that may be used to control the etching rate of TIN with respect to W, and remove any residues from the surface, e.g. organic or inorganic residues that could contain fluorine (F), which composition comprises a) an aliphatic or aromatic sulfonic acid; b) one or more inhibitor(s); c) an aprotic solvent; d) a glycol ether; and e) water. The present invention also relates to a kit comprising said composition in combination with an oxidant and optionally a stabilizer of the oxidant, and the use thereof.