HF RF Power Limiter Control for Reflected Power Protection
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Solution Overview
Problem
Existing systems face challenges in controlling the power supply to semiconductor wafers during processing, making it difficult to manage power reflection effectively and protect components from damage.
Innovation Solution
A power limiter system that includes a controller to monitor power reflection and engage a power limiter filter based on predetermined thresholds and mistuned bins, ensuring safe operation of the HF RF generator by adjusting power supply limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a power limiter is engaged to protect components from damage due to reflected power, then component reliability is improved, but processing rate is reduced
Solution Approach 1:
The power limiter filter is dynamically engaged or disengaged based on real-time monitoring of reflected power conditions. The controller continuously evaluates whether the power limiter should be active, allowing the system to adapt between protection mode and high-performance mode, thus resolving the contradiction between reliability and productivity
Solution Approach 2:
The system implements feedback control by monitoring reflected power towards the HF RF generator and using this information to control the power limiter filter. The controller receives feedback on power reflection conditions and adjusts the power limiter state accordingly, enabling intelligent decision-making between protection and performance
2Object-affected harmful factors
If power supply is limited to protect components, then component safety is improved, but power delivery to wafer is reduced
Solution Approach 1:
The power limiter filter is positioned in the power supply path to preemptively block excessive reflected power before it can reach and damage the HF RF generator components. This preliminary protective action prevents harmful power reflection from affecting sensitive components while allowing full power delivery during normal operation
Data Source
AI summary
A method for controlling a limit on power supplied by a high frequency (HF) radio frequency (RF) generator is described. The method includes determining whether average power reflected towards the HF RF generator is less than a maximum limit, and determining whether power reflected towards the HF RF generator for a number of bins during a cycle is less than a predetermined threshold upon determining that the average power is less than the maximum limit. The method further includes determining whether a number of mistuned bins is greater than a predetermined number in response to determining that the power reflected towards the HF RF generator for the number of bins during the cycle is not less than the predetermined threshold. The method includes engaging a power limiter filter upon determining that the number of mistuned bins is not greater than the predetermined number.