Plasma-Free Halogen Etching of Transition Metals
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Solution Overview
Problem
Conventional etching processes face challenges in selectively removing transition-metal-containing materials without damaging delicate substrate features, as they often rely on wet etches that can cause corrosion and pattern deformation, or dry plasmas that may produce electric arcs and charge buildup, leading to substrate damage.
Innovation Solution
The use of plasma-free dry etching methods involving halogen-containing precursors such as nitrogen trifluoride, diatomic fluorine, or chlorine trifluoride, at controlled temperatures and pressures, to selectively remove transition-metal-containing materials like tungsten, molybdenum, and chromium, while protecting surrounding structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If wet etching is used to remove transition-metal-containing materials, then etching capability is improved, but substrate damage and pattern deformation occur
Solution Approach 1:
The invention changes the chemical parameters of the etching process by using halogen-containing precursors (such as NF3, CF4, SF6, or ClF3) in a plasma-free environment at controlled temperatures (200-400°C) and pressures (0.1-50 Torr). This parameter change enables selective removal of transition-metal-containing materials while avoiding the harmful effects of wet etching, thus resolving the contradiction between etching capability and substrate damage.
Solution Approach 2:
The invention creates an inert plasma-free environment using halogen-containing precursor gases. This inert atmosphere allows the etching reaction to proceed selectively on transition-metal-containing materials without causing charge buildup or electric arcs that would damage the substrate, thereby maintaining both high etching capability and substrate integrity.
2Volume of moving object
If dry plasma etching is used to penetrate constrained trenches, then etching access is improved, but electric arcs and charge buildup damage the substrate
Solution Approach 1:
The invention extracts the harmful plasma component from the etching process while retaining the beneficial chemical etching mechanism. By using halogen-containing precursors in a plasma-free environment, the process maintains ability to penetrate constrained trenches through chemical reactions, but eliminates electric arcs and charge buildup that cause substrate damage.
Solution Approach 2:
The halogen-containing precursor gases act as intermediaries that enable etching in constrained trenches without requiring plasma. These precursors chemically react with transition-metal-containing materials to enable penetration into narrow features while avoiding the formation of electric arcs and charge buildup associated with plasma etching.
3Manufacturing precision
If selective etching of transition-metal-containing materials is achieved, then material specificity is improved, but process complexity increases
Solution Approach 1:
The invention achieves selective etching of transition-metal-containing materials by optimizing specific process parameters: temperature (200-400°C), pressure (0.1-50 Torr), and halogen-containing precursor selection. These parameter changes enable high etch selectivity without requiring complex process sequences, as the chemical reactions are inherently selective under these controlled conditions.
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 allows for precise and selective etching of transition-metal-containing films relative to other materials, preventing substrate damage and maintaining high-quality feature integrity, with improved etch selectivity and reduced risk of corrosion or pattern deformation.
Implementation Method 1
Chemical etching is used for a variety of purposes including transferring a pattern in photoresist into underlying layers
Implementation Method 2
Dry etches produced in local plasmas formed within the substrate processing region
Implementation Method 3
oxidizing the exposed region of the transition-metal-containing material to produce an oxidized material
Data Source
AI summary
Exemplary etching methods may include flowing a halogen-containing precursor into a substrate processing region of a semiconductor processing chamber. The methods may include contacting a substrate housed in the substrate processing region with the halogen-containing precursor. The substrate may define an exposed region of a transition-metal-containing material. The methods may also include removing the transition-metal-containing material. The flowing and the contacting may be plasma-free operations.