Atomic Layer Etching Using Sequential Oxidation and Fluorination
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current atomic layer etching techniques are inadequate for materials resistant to plasma ALE and thermal ALE, as they fail to provide controlled etching for materials like elemental metals and those with volatile metal fluorides.
Innovation Solution
A method involving sequential thermal reactions where a metal substrate is oxidized to form a self-passivating metal oxide layer, followed by fluorination to create a volatile metal fluoride, allowing for controlled atomic layer etching through the removal of these layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If plasma ALE or conventional thermal ALE methods are used, then etching can be achieved for some materials, but they fail to provide controlled etching for materials like elemental metals and those with volatile metal fluorides
Solution Approach 1:
The etching process is divided into multiple sequential self-limiting reactions (oxidation step, fluorination step, and optionally ligand-exchange step) that occur in distinct cycles. Each reaction step is independently controlled and self-limiting, enabling precise atomic-layer removal while expanding material compatibility to include elemental metals and compounds with volatile fluorides that resist conventional ALE methods
Solution Approach 2:
The patent employs sequential changes in chemical parameters by introducing different reactants (oxidizing agents like O3 or H2O2, then fluorinating agents like HF or SF4, and optionally ligand-exchange agents) in alternating cycles. Each parameter change enables a specific reaction that contributes to the overall etching process, allowing controlled removal of diverse materials including those with volatile metal fluorides
2Manufacturing precision
If fluorination reactions are used for materials with volatile metal fluorides, then etching can occur, but the fluorides being gases prevent thermal ALE pathways
Solution Approach 1:
An oxide intermediate layer is formed on the substrate surface through oxidation reactions before fluorination. This oxide intermediate serves as a mediator that enables controlled fluorination reactions even for materials with volatile metal fluorides. The oxide layer allows the fluorinating agent to react in a self-limiting manner, producing volatile metal fluorides that can be removed while maintaining atomic-layer precision
Solution Approach 2:
The oxidation step is performed as a preliminary action before fluorination to create a controlled oxide surface layer. This preliminary oxidation enables subsequent fluorination to proceed in a self-limiting fashion, ensuring atomic-layer control even when the final fluoride product is volatile and would otherwise prevent thermal ALE pathways
3Manufacturing precision
If sequential thermal reactions with multiple steps are used, then etching precision is improved, but process complexity increases
Solution Approach 1:
The etching process uses periodic cycling through oxidation and fluorination reactions, with each cycle removing a controlled atomic layer. This periodic action enables high etching precision through self-limiting reactions, while the cyclic nature allows the system to return to a clean state for each new cycle, managing complexity through repetition of standardized steps
Solution Approach 2:
Each reaction step is self-limiting, automatically stopping when the desired atomic layer is removed without requiring external intervention. The oxidation step self-limits when the oxide layer is formed, and the fluorination step self-limits when volatile fluorides are produced. This self-service characteristic reduces process complexity by eliminating the need for complex real-time control mechanisms
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 enables precise and controlled etching of previously challenging materials, achieving etch rates of 0.1-3.0 Å per cycle with improved surface smoothing and defect removal, enhancing the precision of semiconductor processing.
Implementation Method 1
contacting at least a portion of the surface of the solid substrate with an oxidant, whereby a first metal oxide is formed on the portion of surface of the solid substrate contacted with the oxidant
Implementation Method 2
contacting at least a portion of the surface of the first metal oxide with a fluorinating agent, whereby a volatile metal fluoride is formed
Implementation Method 3
whereby ALE of the solid substrate is promoted
Data Source
AI summary
The invention includes a method of promoting atomic layer etching (ALE) of a surface. In certain embodiments, the method comprises contacting a solid substrate comprising a first metal compound with an oxidant, optionally contacting the solid substrate with a second metal compound, and then contacting the modified solid substrate with a fluorinating agent, whereby ALE of the solid substrate is promoted.