Selective Metal Etching Without Plasma Damage in Deep Features
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Solution Overview
Problem
Conventional etching processes face challenges in selectively removing metal-containing materials without causing damage, deformation, or residue formation, particularly in high aspect ratio features and delicate structures, due to issues with wet etching and plasma etching.
Innovation Solution
A plasma-free etching process using chlorine-containing and oxygen-containing precursors, such as boron trichloride and diatomic oxygen, is employed to selectively remove metal-containing materials like tungsten, molybdenum, or titanium, at controlled temperatures and pressures, without plasma exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If wet etching is used to remove metal-containing materials, then the etching process is simple and cost-effective, but the process cannot penetrate constrained trenches and deforms remaining material structures
Solution Approach 1:
The patent replaces wet chemical etching with a thermal field-based etching process using chlorine and oxygen precursors. The thermal energy activates the precursors to react with metal-containing materials, enabling penetration into constrained trenches while maintaining material structure integrity through controlled thermal reactions rather than mechanical or chemical degradation.
Solution Approach 2:
The patent changes the etching parameters by using specific temperature ranges (250-650°C) and pressure conditions (0.5-30 Torr) to activate chlorine-containing and oxygen-containing precursors. These parameter changes enable the etching process to selectively remove metal-containing materials while preserving the integrity of surrounding delicate structures.
2Manufacturing precision
If plasma etching is used to penetrate constrained trenches, then the etching capability improves, but the substrate is damaged through electric arcs
Solution Approach 1:
The patent substitutes plasma-based etching with a thermal field-based etching process. Instead of using ionized plasma and electric arcs to etch materials, the process uses thermally activated chemical reactions between chlorine/oxygen precursors and metal-containing materials. This eliminates electric arc damage while maintaining effective trench penetration capability.
Solution Approach 2:
The patent introduces chlorine-containing and oxygen-containing precursors as intermediary substances that mediate the etching process. These precursors thermally decompose and react with metal-containing materials to enable trench penetration without requiring direct plasma-substrate interaction, thereby avoiding electric arc damage to the substrate.
3Productivity
If conventional etching processes are used to remove metal-containing materials, then the etching speed is adequate, but residue formation and selectivity control are problematic
Solution Approach 1:
The patent optimizes etching parameters including temperature (250-650°C), pressure (0.5-30 Torr), and precursor flow rates to achieve both high etching speed and excellent selectivity. The chlorine-containing precursor provides aggressive etching for metal-containing materials while the oxygen-containing precursor enhances selectivity and prevents residue formation through controlled oxidation reactions.
Solution Approach 2:
The patent uses a composite etching approach combining chlorine-containing and oxygen-containing precursors. The chlorine component provides high etching rate for metal-containing materials, while the oxygen component enhances selectivity and prevents residue formation. This composite chemical system achieves both productivity and precision requirements.
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 allows for precise and residue-free removal of metal-containing materials, protecting surrounding structures and maintaining etch selectivity, suitable for high aspect ratio and delicate features.
Implementation Method 1
contacting the substrate with the etchant precursor and the oxygen-containing precursor. The methods include selectively removing at least a portion of the metal-containing material relative to the second material
Implementation Method 2
Removing the portion of the metal-containing material may be performed at a temperature less than or about 550° C.
Data Source
AI summary
Exemplary semiconductor processing methods may include providing an etchant precursor and an oxygen-containing precursor into a processing region of a semiconductor processing chamber. A substrate may be housed within the processing region. The substrate may define an exposed region of a metal-containing material and an exposed region of a second material. The methods may include contacting the substrate with the etchant precursor and the oxygen-containing precursor. The methods may include selectively removing at least a portion of the metal-containing material relative to the second material.