Plasma Source Surface Conditioning via Optical Emission Spectroscopy
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Solution Overview
Problem
Plasma processing systems face instability issues due to changes in equipment or materials, affecting surface chemistry and requiring conditioning to achieve stable plasma processing parameters, which is crucial for predictable and reproducible semiconductor wafer processing.
Innovation Solution
The use of optical emission spectroscopy to assess and maintain the conditioning of internal surfaces within plasma processing systems by monitoring emission peaks from plasmas ignited within the system, ensuring equilibrium and stability through the introduction and removal of plasma products, such as hydrogen and fluorine radicals, to stabilize etch rates and selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If equipment or materials are changed in plasma processing systems, then new or improved processing capabilities are achieved, but plasma processing stability is disrupted
Solution Approach 1:
The system performs preliminary surface conditioning of internal chamber components before actual plasma processing begins. This involves exposing the internal surfaces to plasma to modify their surface chemistry and establish equilibrium conditions, thereby preventing future disruptions to plasma stability when equipment changes are made.
Solution Approach 2:
The system uses optical emission spectroscopy to continuously monitor plasma characteristics and provide feedback on surface conditioning status. By analyzing emission spectra, the system can detect changes in surface chemistry and adjust conditioning parameters accordingly, ensuring plasma stability is maintained after equipment modifications.
2Reliability
If internal surfaces are conditioned to achieve stable plasma parameters, then processing predictability is improved, but system downtime increases
Solution Approach 1:
The system performs surface conditioning using plasma generated within the chamber itself, eliminating the need for external conditioning equipment or processes. The plasma processing system conditions its own internal surfaces, thereby reducing downtime while achieving stable processing parameters.
Solution Approach 2:
The conditioning process is designed to be performed during scheduled maintenance intervals or between production batches, maximizing equipment utilization. The optical emission spectroscopy monitoring allows for real-time assessment of conditioning progress, enabling the system to transition to production mode as soon as stability criteria are met, thereby minimizing downtime.
3Measurement precision
If optical emission spectroscopy is used to monitor surface conditioning, then process stability assessment is improved, but system complexity increases
Solution Approach 1:
The optical emission spectroscopy system serves multiple functions: it monitors surface conditioning progress, assesses plasma stability, and provides feedback for process control. By using a single diagnostic tool for multiple purposes, the system avoids adding separate monitoring equipment, thereby limiting the increase in system complexity while maintaining high measurement precision.
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 allows for rapid stabilization of plasma processing conditions, ensuring reliable and reproducible results by monitoring and controlling the plasma's interaction with internal surfaces, reducing downtime and maintaining process stability, thereby enhancing the efficiency and reliability of semiconductor processing.
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 and is oriented such that the captured optical emissions are not affected by interaction of the plasma with a workpiece
Data Source
AI summary
A method of conditioning internal surfaces of a plasma source includes flowing first source gases into a plasma generation cavity of the plasma source that is enclosed at least in part by the internal surfaces. Upon transmitting power into the plasma generation cavity, the first source gases ignite to form a first plasma, producing first plasma products, portions of which adhere to the internal surfaces. The method further includes flowing the first plasma products out of the plasma generation cavity toward a process chamber where a workpiece is processed by the first plasma products, flowing second source gases into the plasma generation cavity. Upon transmitting power into the plasma generation cavity, the second source gases ignite to form a second plasma, producing second plasma products that at least partially remove the portions of the first plasma products from the internal surfaces.