Dual-Frequency RF Control for Stable Plasma Etching Power
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Solution Overview
Problem
Existing plasma etching apparatuses struggle to achieve desired processing characteristics due to variations in plasma electron density and intermodulation distortion, leading to inconsistent processing results across multiple apparatuses.
Innovation Solution
A substrate processing apparatus with dual radio frequency power supplies operating at different frequencies, coupled with a control system that adjusts the effective power based on detected reflected waves to maintain consistent plasma electron density and suppress intermodulation distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single radio frequency power supply is used for plasma generation, then the device structure is simple, but the processing characteristics cannot be precisely controlled due to variations in plasma electron density
Solution Approach 1:
The single radio frequency power supply is divided into two separate power supplies operating at different frequencies. The first power supply (first frequency) generates plasma, while the second power supply (second frequency, lower than first) controls plasma electron density. This segmentation allows independent optimization of each function, achieving precise processing characteristics control while managing device complexity through modular design
Solution Approach 2:
The invention introduces frequency as a critical control parameter by using two different frequencies. The first power supply operates at a higher frequency for plasma generation, while the second power supply operates at a lower frequency to precisely control electron density. This parameter change enables fine-tuned control of plasma characteristics, directly improving manufacturing precision in substrate processing
2Reliability
If reflected waves are not monitored, then the control system is simple, but the effective power cannot be accurately controlled leading to inconsistent processing results
Solution Approach 1:
A sensor is introduced to detect reflected waves from the substrate support, creating a feedback loop. The control unit receives this reflected wave information and adjusts the power supply output accordingly to maintain effective power at the substrate. This feedback mechanism ensures consistent processing results by compensating for variations in real-time, directly improving reliability while the automated control reduces operational complexity
Solution Approach 2:
The control system automatically adjusts power output based on reflected wave detection without requiring manual intervention. The system self-regulates by continuously monitoring reflected waves and modifying the radio frequency power to maintain optimal effective power levels, ensuring processing consistency while simplifying operation
3Manufacturing precision
If dual frequency power supplies are used, then plasma electron density can be controlled, but intermodulation distortion occurs between the two frequencies
Solution Approach 1:
The invention acknowledges that intermodulation distortion will occur between the two frequency power supplies but converts this harmful effect into a beneficial one. The control unit monitors the intermodulation distortion products and uses this information to adjust the power levels and frequencies, transforming the distortion from a nuisance into a diagnostic tool for optimizing plasma control. This approach maintains the advantage of dual-frequency electron density control while mitigating the harmful effects through active management
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
Enables precise control of plasma processing characteristics, ensuring consistent results across multiple apparatuses by stabilizing electron density and minimizing intermodulation distortion, thereby enhancing processing consistency and reproducibility.
Implementation Method 1
a first radio frequency power supply that outputs first radio frequency power with a first frequency to the substrate support
Implementation Method 2
a sensor that detects reflected waves received from the substrate support
Data Source
AI summary
Provided is a substrate processing apparatus comprising: a substrate support on which a substrate is mounted; a first radio frequency power supply that outputs first radio frequency power with a first frequency to the substrate support; a second radio frequency power supply that outputs second radio frequency power with a second frequency lower than the first frequency to the substrate support; a sensor that detects reflected waves received from the substrate support and a processor that controls the first radio frequency power supply so that an effective power, which is equal to a difference between the power of the reflected waves detected by the sensor and the output power of the first radio frequency power supply, reaches a set value.