Silicon Nitride Etching With Cyclic Fluorination and Inert Plasma
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Solution Overview
Problem
Conventional etching processes for silicon nitride materials face challenges in achieving high-quality device fabrication due to issues such as non-uniform etching profiles, pattern loading, bending of structures, and the use of greenhouse gases, which can lead to arcing and environmental concerns.
Innovation Solution
A cyclic etching process using a fluorine-containing precursor followed by an inert precursor is employed, conducted at low temperatures and controlled conditions to form a fluorinated portion of the silicon-and-nitrogen-containing material, which is then removed using plasma effluents of the inert precursor, without the need for polymeric passivation and greenhouse gases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If wet HF etch is used to preferentially remove silicon oxide, then selectivity towards silicon oxide is improved, but penetration into constrained trenches is poor and deformation of remaining material occurs
Solution Approach 1:
The patent changes the physical state of the etching medium from liquid (wet HF) to gaseous/plasma phase, enabling the etchant to penetrate constrained trenches effectively while maintaining selectivity through controlled chemical reactions with silicon oxide
Solution Approach 2:
The patent replaces the chemical wet etching mechanism with a plasma-based physical-chemical etching process, using ion bombardment and reactive species to achieve both trench penetration and selective removal of silicon oxide without liquid deformation issues
2Ease of operation
If local plasma is used to penetrate constrained trenches, then trench penetration capability is improved, but substrate damage through electric arcs occurs
Solution Approach 1:
The patent uses an inert or controlled atmosphere plasma process that prevents uncontrolled arcing and electric discharge on the substrate, maintaining trench penetration capability while eliminating substrate damage through controlled plasma chemistry and reduced ion bombardment energy
Solution Approach 2:
The patent adjusts plasma process parameters such as power density, gas composition, and pressure to achieve controlled etching without excessive ion bombardment that causes substrate damage, maintaining penetration capability while reducing harmful effects
3Productivity
If conventional etching processes are used for silicon nitride, then etching capability is achieved, but non-uniform etching profiles and pattern loading occur
Solution Approach 1:
The patent employs a cyclic etching process with periodic alternation between etching steps and pause intervals, allowing uniform reaction progression and preventing pattern loading effects while maintaining high etching capability through repeated controlled cycles
Solution Approach 2:
The patent maintains continuous fluorine precursor exposure during etching cycles to ensure uniform reaction progression across the substrate surface, preventing non-uniform profiles while achieving high etching rates through sustained chemical activity
4Productivity
If greenhouse gases are used in etching processes, then etching performance is achieved, but environmental impact and arcing increase
Solution Approach 1:
The patent replaces harmful greenhouse gas precursors with environmentally benign alternatives such as fluorine-containing compounds that decompose into harmless byproducts, maintaining etching performance while eliminating environmental damage and reducing arcing through controlled chemistry
Solution Approach 2:
The patent changes the chemical composition of etching precursors from greenhouse gases to environmentally friendly fluorine-containing compounds, maintaining etching effectiveness through alternative chemical mechanisms while eliminating harmful environmental effects
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 method achieves a high-directional etch with reduced arcing and environmental impact, ensuring uniform etching profiles and minimizing lateral etching, while maintaining substrate integrity.
Implementation Method 1
contacting the substrate with the fluorine-containing precursor. The contacting may form a fluorinated portion of the silicon-and-nitrogen-containing material
Implementation Method 2
flowing an inert precursor into the processing region of the semiconductor processing chamber. The methods may include forming plasma effluents of the inert precursor
Implementation Method 3
contacting the substrate with the plasma effluents of the inert precursor. The contacting may remove the fluorinated portion of the silicon-and-nitrogen-containing material
Data Source
AI summary
Exemplary semiconductor processing methods may include flowing a fluorine-containing precursor into a processing region of a semiconductor processing chamber. A substrate may be positioned within the processing region. The substrate may include a layer of a silicon-and-nitrogen-containing material. The methods may include contacting the substrate with the fluorine-containing precursor. The contacting may form a fluorinated portion of the silicon-and-nitrogen-containing material. The methods may include flowing an inert precursor into the processing region of the semiconductor processing chamber. The methods may include forming plasma effluents of the inert precursor. The methods may include contacting the substrate with the plasma effluents of the inert precursor. The contacting may remove the fluorinated portion of the silicon-and-nitrogen-containing material. The method may be performed at a chamber operating temperature of less than or about 20° C.