Selective Ion Mass Segregation in Pulsed Plasma Atomic Layer Etching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Atomic layer etching processes face challenges in achieving high selectivity and throughput due to the need for physical separation of reactive and inert precursors, which increases cycle time and limits scalability beyond nanometer scales, especially in high-volume manufacturing.
Innovation Solution
The method utilizes the difference in ion mass between lighter, inert ions and heavier, reactive ions in conjunction with bias voltage modulation to achieve surface modification and etching without physical separation of precursors, allowing the same gas chemistry to be maintained in the process chamber during an ALE cycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If physical separation of reactive and inert precursors is implemented through cyclic feeding and purging, then selectivity and control are improved, but cycle time increases and throughput decreases
Solution Approach 1:
The patent applies periodic pulsing of the plasma source power to alternately generate reactive ions for surface modification and inert ions for etching. This temporal periodic action allows both precursors to be present simultaneously in the chamber while achieving sequential surface modification and removal, thereby eliminating the need for purging cycles and improving throughput while maintaining etch selectivity
Solution Approach 2:
The patent dynamically modulates the plasma source power between different levels to control the type of ions generated. By adjusting the power dynamically, the system transitions between generating reactive ions (for modification) and inert ions (for etching), enabling precise control over the surface modification and removal process without physical separation of precursors
2Productivity
If fast switching mass flow controllers and small chamber volumes are used to reduce cycle time, then throughput is improved, but device complexity and cost increase
Solution Approach 1:
The patent changes the operational parameters of the plasma source by modulating the RF power level between two distinct states. This parameter change allows the same plasma source to generate different ion types (reactive vs. inert) without requiring additional hardware components, thereby reducing device complexity while achieving fast cycle times
3Productivity
If reactive precursor and inert gas are continuously present in the chamber, then etch rate and throughput are improved, but unwanted bombardment and exposure to wrong species occur
Solution Approach 1:
The patent uses periodic pulsing of the plasma source power to control which ions are present in the chamber at any given time. During the modification phase, reactive ions are generated; during the etching phase, inert ions are generated. This periodic control prevents unwanted bombardment while allowing continuous presence of both precursors, thereby achieving high etch rates without harmful effects
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 etch rate, throughput, and cost-efficiency by enabling preferential ion bombardment with lighter ions, reducing the need for purging and allowing continuous use of reactive precursor and inert gas combinations, thus improving the efficiency of the plasma ALE process.
Implementation Method 1
The difference in ion mass of lighter, inert ions (which have a higher mobility) and heavier, reactive ions is advantageously utilized in conjunction with bias voltage modulation of the ALE process
Implementation Method 2
By modulating the bias voltage, preferential lighter ion bombardment is achieved with lighter inert ions (or lighter less reactive ions) without the need to physically separate or purge the reactive precursors and inert gases supplied to the process chamber
Implementation Method 3
performing the layer modification step by applying a source voltage to a first electrode disposed within the process chamber to generate an electric field that dissociates and converts the first process gas and the second process gas into a plasma
Data Source
AI summary
Differences in ion mass of lighter ions (having a higher mobility) and heavier ions are utilized in conjunction with bias voltage modulation of an atomic layer etch (ALE) to provide a fast ALE process. The difference in ion mobility achieves surface modification with reactive neutral species in the absence of a bias voltage, and ion bombardment with lighter ions (e.g., inert or less reactive ions) in the presence of a bias voltage. By modulating the bias voltage, preferential ion bombardment is achieved with lighter ions without the need to physically separate or purge the reactive precursors and inert gases supplied to the process chamber for a given ALE cycle. A “fast” plasma ALE process is provided which improves etch rate, throughput and cost-efficiency by enabling the same gas chemistry composition (e.g., reactive precursor and inert gas combination) to be kept in the process chamber during a given ALE cycle.