Pulsed Plasma Atomic Layer Etching for Sub-20 nm Precision
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Solution Overview
Problem
Traditional atomic layer etching processes are too slow, damage substrates, and lack precision for fabricating future integrated circuits with sub-20 nm structures, requiring a novel method for efficient and controlled etching with atomic layer resolution.
Innovation Solution
A pulsed plasma source system with a spiral coil electrode, Faraday shield, and counter electrode is used to control ion energy distribution, allowing for precise etching by pulsing RF power and applying bias voltages synchronously with plasma pulses, reducing gas usage and improving etching efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional atomic layer etching processes are used, then etching precision can be achieved, but etching cycle time becomes excessively long
Solution Approach 1:
The patent applies periodic pulsed plasma cycles with multiple distinct phases (chemisorption, purge, etching, evacuation) to achieve atomic layer precision. Each pulse delivers a controlled sequence of reactions that removes exactly one atomic layer, maintaining precision while reducing total cycle time through optimized phase durations and overlapping operations.
Solution Approach 2:
The patent performs preliminary chemisorption of reactant gas onto the substrate surface before the actual etching step. This pre-saturation of the surface with reactants ensures that the subsequent ion bombardment removes only the intended atomic layer, maintaining precision while allowing for faster etching rates through pre-prepared reaction sites.
2Manufacturing precision
If traditional atomic layer etching processes are used, then atomic layer precision can be achieved, but substrate damage occurs
Solution Approach 1:
The patent uses periodic pulsed plasma cycles that alternate between gentle chemisorption phases and controlled etching phases. This periodic action allows the substrate to recover between intense ion bombardment events, reducing cumulative damage while maintaining atomic layer precision through the self-limiting nature of each pulse cycle.
Solution Approach 2:
The patent introduces reactant gases as intermediaries that form chemisorbed layers on the substrate surface before ion bombardment. These intermediate chemical layers facilitate selective removal of material while protecting the underlying substrate from direct ion damage, achieving precision etching with minimal substrate harm.
3Manufacturing precision
If traditional atomic layer etching processes are used, then etching control can be maintained, but productivity becomes too low for practical manufacturing
Solution Approach 1:
The patent implements periodic pulsed plasma cycles with optimized timing for each phase. By carefully controlling the duration and sequencing of chemisorption, purge, etching, and evacuation phases, the process achieves both atomic layer control and improved throughput through efficient use of process time and reduced idle periods between cycles.
Solution Approach 2:
The patent maintains continuous useful action by overlapping process phases and minimizing idle time. The chemisorption phase prepares the surface while the purge phase begins, and the etching phase begins while evacuation starts, ensuring that the substrate is continuously processed without unnecessary waiting periods, thereby improving productivity while maintaining control.
4Manufacturing precision
If gas pulsing is used in traditional ALET, then etching precision can be achieved, but gas consumption increases and pumping time is required
Solution Approach 1:
The patent uses periodic pulsed plasma cycles with controlled gas introduction and removal phases. Reactant gas is introduced only during chemisorption phases and completely purged during dedicated purge phases, minimizing overall gas consumption while maintaining precision through controlled reaction windows. The periodic nature ensures gas is only present when needed for specific process steps.
Solution Approach 2:
The patent applies partial gas pulsing where reactant gas is introduced at controlled partial pressures rather than continuous full flow. This partial action provides sufficient reactants for precise chemisorption and etching while significantly reducing total gas consumption compared to continuous gas flow methods, maintaining precision with reduced material usage.
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
The method significantly reduces etching cycle time, enhances precision, and minimizes substrate damage, enabling the fabrication of nanodevices with atomic layer resolution while reducing gas consumption and operational costs.
Implementation Method 1
generating a plasma containing reactants and ions from the feed gas
Implementation Method 2
spiral coil electrode disposed around a tube
Implementation Method 3
saturating a substrate surface with the reactants to form a product layer
Implementation Method 4
removing the product layer by exposing the product layer to the ions
Data Source
AI summary
A system and method for rapid atomic layer etching (ALET) including a pulsed plasma source, with a spiral coil electrode, a cooled Faraday shield, a counter electrode disposed at the top of the tube, a gas inlet and a reaction chamber including a substrate support and a boundary electrode. The method includes positioning an etchable substrate in a plasma etching chamber, forming a product layer on the surface of the substrate, removing a portion of the product layer by pulsing a plasma source, then repeating the steps of forming a product layer and removing a portion of the product layer to form an etched substrate.