Plasma Source RF Frequency Tuning for Faster Low-Reflection Startup
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Solution Overview
Problem
Existing plasma processing apparatuses face challenges in stabilizing plasma quickly and efficiently, particularly in suppressing the degree of reflection of radio frequency power, which affects processing stability and efficiency.
Innovation Solution
A plasma processing apparatus that includes a chamber, a radio frequency power supply, and a controller. The controller sets the source frequency of the source radio frequency power when supplied alone to suppress the degree of reflection, using pulsed high-frequency (HF) RF to quickly stabilize the plasma.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional plasma processing apparatus supplies source radio frequency power continuously, then plasma generation is maintained, but the degree of reflection of radio frequency power increases and plasma stabilization is slow
Solution Approach 1:
The patent applies periodic action by pulsing the source radio frequency power in alternating periods with the bias radio frequency power, rather than supplying source power continuously. This periodic supply pattern reduces the degree of reflection of source radio frequency power and accelerates plasma stabilization. The controller alternates between supplying source power alone, bias power alone, or both powers in a coordinated periodic manner.
2Loss of energy
If source radio frequency power is supplied alone at fixed frequency, then plasma generation is achieved, but the degree of reflection cannot be suppressed effectively
Solution Approach 1:
The patent implements dynamics by making the source frequency variable rather than fixed. The controller dynamically adjusts the source frequency based on the degree of reflection of source radio frequency power, changing it from an initial frequency to a different frequency when reflection exceeds a threshold. This dynamic frequency adjustment suppresses radio frequency power reflection while maintaining plasma generation.
Solution Approach 2:
The patent employs feedback control where the controller monitors the degree of reflection of source radio frequency power and adjusts the source frequency accordingly. When the degree of reflection exceeds a predetermined threshold, the controller changes the source frequency to a different value to reduce reflection. This closed-loop feedback mechanism optimizes power transfer efficiency.
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
The solution effectively reduces the degree of reflection of the source radio frequency power, accelerates plasma stabilization, suppresses abnormal discharges, and improves the reproducibility of the effective power level, leading to enhanced processing stability and efficiency.
Implementation Method 1
a radio frequency power supply configured to supply a source radio frequency power to generate a plasma from a gas in the chamber
Implementation Method 2
a bias radio frequency power to attract ions from the plasma generated in the chamber into the substrate
Data Source
AI summary
A disclosed plasma processing apparatus includes a chamber, a radio frequency power supply, and circuitry. The radio frequency power supply is configured to supply a source radio frequency power to generate a plasma from a gas in the chamber. The circuitry is configured to set a source frequency of the source radio frequency power when the source radio frequency power is supplied alone to suppress a degree of reflection of the source radio frequency power in accordance with the source frequency and the degree of reflection of the source radio frequency power when the source radio frequency power is supplied alone beforehand.