Capacitively Coupled Plasma Ion Suppression for Etch Precision
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Solution Overview
Problem
Plasma deposition and etching processes for semiconductor fabrication face challenges in precision control due to energetic plasmas that can over-etch shallow trenches and gaps, and cause unwanted reactions in deposited materials, leading to performance issues.
Innovation Solution
The implementation of an ion suppression element between the plasma and the substrate, which can be part of the gas/precursor delivery equipment or a partition, reduces or eliminates ionically charged species reaching the substrate, allowing for more precise control of etch rate, selectivity, and deposition chemistry by controlling the concentration of ionic species.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional plasma deposition and etching processes are used, then material can be deposited and etched on substrate surfaces, but etching precision deteriorates due to over-etching of shallow trenches and gaps by energetic plasma species
Solution Approach 1:
A plasma gate electrode is introduced as an intermediary component positioned between the plasma source and the substrate. This gate electrode selectively filters plasma species, allowing neutral radicals to pass through while blocking charged ions, thereby preventing over-etching of shallow trenches and gaps while maintaining deposition and etching capabilities
Solution Approach 2:
The plasma gate electrode changes the plasma parameters by controlling the concentration and energy distribution of plasma species reaching the substrate. By adjusting the gate electrode potential and geometry, the system can modulate ion-to-radical ratios and plasma flux, achieving precise control over etching and deposition processes
2Temperature
If conventional plasma processes are used, then reactive radical and ion species can be generated at lower temperatures, but unwanted reactions occur in deposited materials due to energetic ion species
Solution Approach 1:
The plasma gate electrode serves as a selective filter that separates beneficial neutral radical species from harmful charged ion species. Neutral radicals pass through to the substrate for desired chemical reactions and material deposition, while charged ions are blocked, preventing unwanted energetic reactions that would damage deposited materials
Solution Approach 2:
The system creates different plasma species compositions in different spatial regions. The plasma gate electrode establishes a gradient where the plasma source region contains both ions and radicals, while the substrate region receives primarily neutral radicals, providing local quality control over plasma composition
3Productivity
If plasma is positioned close to the substrate surface, then deposition efficiency is improved, but control over plasma components contacting the substrate deteriorates
Solution Approach 1:
The plasma gate electrode is positioned between the plasma source and substrate, acting as a controllable intermediary that maintains efficient plasma-substrate interaction while providing precise control over which plasma components reach the substrate. The gate's potential and geometry can be adjusted to optimize both deposition efficiency and plasma component control
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 the precision and control over plasma-assisted etch and deposition processes, reducing unwanted reactions and improving the performance of deposited materials by minimizing the impact of energetic ions on the substrate.
Implementation Method 1
These processes typically involve the formation of a plasma from plasma-generating gases that are exposed to electric fields of sufficient power inside the processing chamber to cause the gases to ionize
Implementation Method 2
Systems and methods are described for improved control of the environment between a plasma and the surfaces of a substrate wafer... a capacitively coupled plasma (CCP) unit positioned inside the process chamber
Implementation Method 3
The improved control may be realized at least in part by an ion suppression element positioned between the plasma and the substrate that reduces or eliminates the number of ionically-charged species that reach the substrate
Data Source
AI summary
Substrate processing systems are described that have a capacitively coupled plasma (CCP) unit positioned inside a process chamber. The CCP unit may include a plasma excitation region formed between a first electrode and a second electrode. The first electrode may include a first plurality of openings to permit a first gas to enter the plasma excitation region, and the second electrode may include a second plurality of openings to permit an activated gas to exit the plasma excitation region. The system may further include a gas inlet for supplying the first gas to the first electrode of the CCP unit, and a pedestal that is operable to support a substrate. The pedestal is positioned below a gas reaction region into which the activated gas travels from the CCP unit.