Plasma Surface Conditioning via Optical Emission Monitoring
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Solution Overview
Problem
Plasma processing systems in semiconductor manufacturing face challenges in rapidly stabilizing process conditions after equipment changes or exposure to atmospheric air, leading to variability in etch rate and selectivity, which affects the reliability and efficiency of wafer processing.
Innovation Solution
The use of optical emission spectroscopy to assess and condition internal surfaces of plasma processing systems by monitoring emission peaks from plasmas generated within the system, ensuring equilibrium and stability through controlled plasma processes, including the use of hydrogen-containing gases to remove excess oxygen and fluorine radicals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If plasma chamber components are used after exposure to atmospheric air or first-time use, then the equipment can be operated, but the plasma processing parameters become unstable and vary over time
Solution Approach 1:
The patent applies preliminary action by performing surface conditioning of plasma chamber components before actual wafer processing begins. The system automatically conducts conditioning plasma cycles that modify the surface chemistry of chamber walls, electrodes, and other internal surfaces to establish a stable baseline state. This preliminary conditioning eliminates the need for subsequent stabilization periods during production, allowing immediate consistent processing without time loss.
Solution Approach 2:
The patent implements feedback mechanisms by monitoring plasma parameters such as emission spectra, impedance, or other diagnostic signals during conditioning and processing operations. The system uses this feedback to determine when surface conditioning is complete and to maintain stable processing conditions. The feedback loop allows the system to automatically adjust or terminate conditioning based on real-time measurements of surface state, ensuring reliability without excessive conditioning time.
2Reliability
If surface chemistry of plasma system components is changed to stabilize processing, then process stability improves, but equipment downtime increases due to conditioning requirements
Solution Approach 1:
The system performs surface conditioning as a preliminary action that prepares the plasma chamber for stable operation before production processing begins. By automatically conditioning surfaces in advance and establishing a stable chemical state, the system ensures that subsequent processing runs maintain consistent etch rates and selectivity without requiring repeated conditioning cycles, thereby maximizing equipment availability.
Solution Approach 2:
The patent applies self-service by implementing automated conditioning sequences that the system performs without manual intervention. The system autonomously monitors its own surface state through plasma diagnostics and initiates appropriate conditioning plasma cycles to maintain optimal surface chemistry. This self-service capability ensures process stability while minimizing downtime, as the system manages its own conditioning needs without requiring operator attention or equipment shutdown.
3Measurement precision
If optical emission spectroscopy is used to monitor plasma emissions, then surface conditioning can be assessed in real-time, but system complexity increases
Solution Approach 1:
The patent uses optical emission spectroscopy as an intermediary measurement technique that indirectly assesses surface conditioning state by analyzing plasma emission spectra. Rather than directly measuring surface properties, the system monitors the plasma's optical emissions, which are influenced by surface chemistry. This intermediary approach provides precise assessment of conditioning status without requiring direct contact with or complex modification of the chamber surfaces, maintaining relatively simple implementation.
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 method enables rapid stabilization of plasma processing conditions, ensuring predictable and reproducible wafer processing results by monitoring and adjusting plasma emissions to maintain stable etch rates and selectivity, thereby reducing equipment downtime and processing costs.
Implementation Method 1
A power supply provides electrical power across the first and second electrodes to ignite a plasma with the one or more plasma source gases in the plasma generation cavity to produce the plasma products
Implementation Method 2
Optical emissions from the plasma are captured with an optical probe that is disposed adjacent the plasma generation cavity
Data Source
AI summary
In an embodiment, a plasma source includes a first electrode, configured for transfer of one or more plasma source gases through first perforations therein; an insulator, disposed in contact with the first electrode about a periphery of the first electrode; and a second electrode, disposed with a periphery of the second electrode against the insulator such that the first and second electrodes and the insulator define a plasma generation cavity. The second electrode is configured for movement of plasma products from the plasma generation cavity therethrough toward a process chamber. A power supply provides electrical power across the first and second electrodes to ignite a plasma with the one or more plasma source gases in the plasma generation cavity to produce the plasma products. One of the first electrode, the second electrode and the insulator includes a port that provides an optical signal from the plasma.