Wet Atomic Layer Etching Purge Timing for Throughput and Surface Roughness
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Solution Overview
Problem
Conventional wet atomic layer etching (ALE) processes are slow and inefficient, leading to low throughput in high-volume manufacturing due to stringent requirements for reaction saturation and purge steps, which often result in increased post-etch surface roughness, especially when etching polycrystalline materials.
Innovation Solution
A dynamic ALE cycle timing schedule is implemented, adjusting purge times between cycles and individual surface modification and dissolution steps to balance throughput, etch rate, and post-etch surface roughness, allowing for increased etch rates initially while maintaining low roughness in later stages by dynamically adjusting purge times based on aspect ratio changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional wet ALE processes use long purge times to ensure reaction saturation and prevent mixing, then etching specificity and surface quality are improved, but throughput and productivity deteriorate
Solution Approach 1:
The patent implements dynamic purge timing where the purge duration is adjusted based on the aspect ratio of the substrate features. For low aspect ratio features, shorter purge times are used to increase throughput, while for high aspect ratio features, longer purge times are maintained to ensure complete reactant removal and prevent mixing. This dynamic adjustment resolves the contradiction by adapting the purge time to the specific geometric requirements rather than using a fixed conservative value for all cases.
Solution Approach 2:
The patent changes the purge time parameter dynamically during the etching process based on monitored aspect ratio changes. By adjusting this critical process parameter in real-time, the system achieves optimal balance between etching specificity (requiring sufficient purge time) and productivity (requiring minimal cycle time), thereby resolving the technical contradiction between these two opposing requirements.
2Manufacturing precision
If conventional wet ALE processes use extended purge steps to maintain low surface roughness, then post-etch surface quality is improved, but process time and productivity worsen
Solution Approach 1:
The system dynamically adjusts purge timing based on aspect ratio monitoring to maintain surface quality while reducing overall process time. For features where aspect ratio indicates low risk of solution mixing, the purge time is reduced accordingly, maintaining surface roughness control only where necessary while minimizing time loss in other regions.
Solution Approach 2:
The patent applies different purge timing strategies to different regions or feature types based on their aspect ratios. Rather than uniformly extending purge time for all features, the system applies extended purge only where geometric characteristics indicate it is necessary to prevent solution mixing and maintain surface quality, thereby reducing overall process time while maintaining surface roughness control where critical.
3Productivity
If conventional wet ALE processes reduce purge times to increase throughput, then productivity is improved, but solution mixing occurs leading to increased surface roughness
Solution Approach 1:
The patent implements real-time monitoring of aspect ratio during the etching process and dynamically adjusts purge timing in response. When aspect ratio indicates that solution mixing is unlikely, shorter purge times are used to maximize throughput. When aspect ratio changes indicate potential mixing risks, purge time is extended to prevent surface roughness degradation. This dynamic response resolves the contradiction by adapting purge time to actual process conditions rather than using fixed conservative values.
Solution Approach 2:
The system uses feedback from aspect ratio monitoring to control purge timing. The monitored aspect ratio provides real-time information about the etching progress and solution distribution, which feeds back to the purge timing control system. This closed-loop feedback mechanism enables the system to automatically adjust purge duration to maintain surface quality while optimizing throughput, resolving the contradiction between these two parameters.
4Reliability
If conventional wet ALE processes use multiple cycles with full purge steps, then complete material removal is achieved, but manufacturing efficiency deteriorates
Solution Approach 1:
The patent dynamically determines when to terminate etching cycles based on real-time aspect ratio monitoring rather than using a fixed predetermined number of cycles with full purge steps. The system continues cycles only as long as aspect ratio indicates complete material removal has not been achieved, and terminates early when monitoring confirms completion. This dynamic termination criterion ensures reliable complete removal while eliminating unnecessary cycles and purge steps, thereby improving manufacturing efficiency.
Solution Approach 2:
The etching process monitors its own progress through aspect ratio changes and self-determines when material removal is complete, eliminating the need for external inspection or fixed-cycle protocols. The process serves itself by using the etching-induced aspect ratio changes as the termination criterion, which ensures complete removal reliability while maximizing efficiency by avoiding unnecessary additional cycles.
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 enhances throughput and maintains acceptable surface roughness, improving the efficiency and quality of the etching process for polycrystalline materials by optimizing purge times throughout the etching process.
Implementation Method 1
chemically modifying an exposed surface of the material to provide a modified surface layer, wherein the exposed surface is chemically modified by oxidation of the material
Implementation Method 2
selectively removing the modified surface layer of the material by exposing the modified surface layer to a dissolution solution to dissolve the modified surface layer
Data Source
AI summary
The present disclosure provides various embodiments of an improved wet atomic layer etching (ALE) process. More specifically, the present disclosure provides various embodiments of methods that improve a wet ALE process by providing a dynamic ALE cycle timing schedule that balances throughput and etch rate with post-etch surface roughness. As described in more detail below, the methods disclosed herein may adjust the purge timing between ALE cycles and/or between individual surface modification and selective dissolution steps to provide a desired throughput, etch rate and/or post-etch surface roughness in a wet ALE process.