RF Matching Network Phase-Gap Sensing for Substrate Processing
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Solution Overview
Problem
Existing RF sensors in substrate processing tools face challenges in accurately calculating impedance or power due to phase differences between voltage and current approaching ±90 degrees, which can lead to inaccurate measurements and increased noise or modeling errors.
Innovation Solution
The use of voltage/current (V/I) probes connected to the input and output sides of a matching network, coupled with a processor, to detect a minimum phase gap between voltage and current, enabling precise impedance tuning and process control by measuring peak or RMS values and phase at a target frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If RF sensors use analog circuits or half analog circuits to calculate impedance using measured voltage/current, then chamber matching can be maintained, but measurement accuracy deteriorates when phase difference between voltage and current approaches ±90 degrees due to increased noise and modeling errors
Solution Approach 1:
The patent replaces analog circuit-based impedance calculation with a digital signal processing approach. V/I probes measure voltage and current signals, which are then processed digitally by a processor that applies mathematical models and algorithms to calculate impedance. This substitution of digital processing for analog computation eliminates the phase-dependent accuracy issues inherent in analog circuits, as digital systems can accurately handle signals across the full phase range including ±90 degrees without the noise and modeling errors that plague analog implementations.
2Productivity
If phase difference between voltage and current approaches ±90 degrees in RF transmission lines, then chamber matching operation can continue, but measurement accuracy deteriorates due to increased noise and modeling errors
Solution Approach 1:
The patent replaces analog circuit-based impedance calculation with a digital signal processing approach. V/I probes measure voltage and current signals, which are then processed digitally by a processor that applies mathematical models and algorithms to calculate impedance. This substitution of digital processing for analog computation eliminates the phase-dependent accuracy issues inherent in analog circuits, as digital systems can accurately handle signals across the full phase range including ±90 degrees without the noise and modeling errors that plague analog implementations.
Solution Approach 2:
The patent implements comprehensive signal processing that goes beyond simple impedance calculation. The system measures both magnitude and phase of voltage and current signals, applies multiple mathematical models, and performs detailed analysis to compensate for potential errors. This excessive measurement and processing approach ensures accurate impedance determination even in challenging phase conditions where simpler methods would fail.
Data Source
AI summary
Methods and apparatus for processing a substrate are provided herein. For example, apparatus can include a first voltage/current (V/I) probe configured to connect to an input side of a matching network of the processing chamber and a second V/I probe configured to connect to an output side of the matching network and a processor coupled to the first V/I probe and the second V/I probe and configured to, based on a phase gap between a V and I of an RF signal detected by at least one of the first V/I probe or the second V/I probe at a target frequency, detect a minimum phase gap between the V and I, and control at least one of impedance tuning of the matching network or process control of the processing chamber using at least one of a peak or RMS of V, I and phase measured at the target frequency or under sweeping frequency.