Chlorination-Based Atomic Layer Etching of Metal Oxides
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Solution Overview
Problem
Conventional atomic layer etching techniques face challenges in achieving precise atomic-scale control and high etch rates, particularly for non-silicon metal oxides, due to reliance on fluorination chemistry, which results in low volatility and damage to sensitive materials.
Innovation Solution
The method employs chlorination-based atomic layer etching using boron trichloride (BCl3) for surface modification and ligand-exchange reagents like borane, amine, alcohol, carboxylic acid, or beta-diketone for removal, avoiding fluorination and enhancing etch rates while preventing damage to other materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If fluorination chemistry is used for atomic layer etching of metal oxides, then atomic-scale control is achieved, but etch rate is low and damage to sensitive materials occurs
Solution Approach 1:
The patent changes the chemical parameters by switching from fluorination chemistry to chlorination chemistry. Specifically, it uses boron trichloride (BCl3) as the precursor gas instead of fluorine-based precursors, and employs ligand-exchange reagents (such as organometallic compounds with beta-diketonate, acetylacetonate, or other ligands) instead of traditional fluorine-based etchants. This parameter change enables both atomic-scale control and significantly improved etch rates for metal oxide films.
Solution Approach 2:
The patent introduces ligand-exchange reagents as intermediary substances that facilitate the etching process. These reagents first adsorb onto the metal oxide surface to form intermediate complexes, which then react with BCl3 to form volatile products. This intermediary mechanism enables precise atomic-layer removal while avoiding the damage caused by direct fluorine attack, thus resolving the contradiction between precision and productivity.
2Productivity
If conventional etching techniques are used, then high etch rate is achieved, but atomic-scale precision and dimensional control are lost
Solution Approach 1:
The patent segments the etching process into distinct sequential steps: (1) surface preparation and ligand-exchange reagent adsorption, (2) BCl3 exposure for controlled reaction, and (3) product removal. This segmentation allows each step to be self-limiting and independently controlled, enabling atomic-scale precision while maintaining high overall etch rates through optimized cycle frequencies.
3Adaptability or versatility
If fluorine-based ALE is used for metal oxide etching, then selective etching is achieved, but fluorine-sensitive materials are damaged
Solution Approach 1:
Instead of using fluorine-based chemistry that attacks metal oxides directly, the patent inverts the approach by using chlorination chemistry with BCl3 combined with ligand-exchange reagents. This inverted chemical pathway achieves selective etching of metal oxides through a different mechanism that does not involve direct fluorine attack, thereby preserving fluorine-sensitive materials while maintaining selectivity.
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 provides selective and precise etching of metal oxides with improved etch rates and material selectivity, suitable for advanced semiconductor applications such as FinFETs and Gate-All-Around transistors, without damaging fluorine-sensitive materials.
Implementation Method 1
exposing the metal oxide containing film to a first gas stream including boron trichloride (BCl3)
Implementation Method 2
exposing the metal mixed-anion compounds to a second gas stream including a borane reagent, an amine reagent, an alcohol, a carboxylic acid, or a beta-diketone
Data Source
AI summary
In one example, a method of processing a substrate includes loading the substrate in a process chamber, where the substrate includes a metal oxide containing film to be etched. The method further includes performing of an atomic layer etching including a plurality of cyclic processes, each of the plurality of cyclic processes including exposing the metal oxide containing film to a first gas stream including boron trichloride (BCl3), and exposing the metal oxide containing film to a second gas stream including borane, amine, alcohol, carboxylic acid, carboxamide, or beta-diketone reagent.