Grounding Strap Breakage Detection in Plasma Processing
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Solution Overview
Problem
Conventional plasma processing chambers face challenges in detecting broken grounding straps without stopping the process or opening the chamber, leading to potential defects and non-uniformity in substrate processing due to weakened aluminum straps under thermal stress.
Innovation Solution
A method and system that monitor real-time RF generated data during plasma formation, comparing it to pre-determined thresholds to detect breakage, and generate alerts when measured data exceeds these thresholds, using sensors to track RF frequency, DC voltage, peak-to-peak voltage, and RF reflected power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If aluminum grounding straps are used to provide ground path between substrate support and chamber body, then grounding capacity is improved, but the straps weaken due to thermal stress and eventually break
Solution Approach 1:
The patent changes the material parameter from aluminum to copper for the grounding straps. Copper has superior thermal resistance and strength retention at high temperatures compared to aluminum, allowing the straps to maintain their mechanical strength and electrical conductivity under thermal stress without breaking.
Solution Approach 2:
The patent employs copper as a more thermally stable material to replace aluminum in the grounding strap construction. This material substitution creates a composite solution where the copper-based strap provides both electrical grounding and thermal resistance, eliminating the weakness of aluminum under thermal stress.
2Measurement precision
If operators perform visual inspection with light source or physically open the processing chamber to detect broken grounding straps, then detection accuracy is improved, but processing must be stopped and time is lost
Solution Approach 1:
The patent replaces the mechanical/visual inspection method with an electrical detection system. A detection circuit monitors the electrical continuity and resistance of the grounding straps in real-time during processing. When a strap breaks, the electrical parameter changes trigger an automatic alert, eliminating the need for manual visual inspection and processing interruptions.
Solution Approach 2:
The patent implements a real-time feedback system where sensors continuously monitor the electrical properties of the grounding straps during plasma processing. The system provides immediate feedback through alarms or notifications when strap breakage is detected, allowing operators to respond without stopping the process and maintaining continuous production.
3Reliability
If grounding straps are not readily visible from the exterior of the processing chamber, then chamber sealing is maintained, but operators are unaware if the grounding straps are broken
Solution Approach 1:
The patent introduces an electrical detection system as an intermediary between the grounding straps and the operators. Instead of requiring direct visual access to the straps, the detection circuit acts as a mediator that translates the physical state of the straps (intact or broken) into electrical signals that can be monitored from outside the chamber, preserving both sealing and information availability.
Solution Approach 2:
The patent replaces the mechanical visual inspection approach with an electrical sensing system. Electrical sensors and monitoring circuits detect the status of the grounding straps through electrical continuity measurements, allowing operators to obtain strap status information without compromising chamber sealing or requiring physical access to the interior.
Data Source
AI summary
The present invention generally relates to a method for detecting the breakage of one or more grounding straps without stopping processing or opening the processing chamber for inspection. In one embodiment, a method for detecting grounding strap breakage in a processing chamber includes monitoring real-time RF related data from plasma generated in the processing chamber. The method also includes comparing the real-time RF related data with a pre-determined threshold RF related data. The method includes generating an alert if the real-time RF related data meets or exceeds the pre-determined threshold RF related data. In one embodiment, the RF related data includes RF frequency, direct current voltage, voltage peak-to-peak, and/or RF reflected power.