Plasma Processing Apparatus Stabilizes Reflection Convergence Time
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Solution Overview
Problem
Plasma processing apparatuses face instability due to variations in reflection convergence time when radio-frequency pulses for bias are driven intermittently, leading to binarization and fluctuation in matching positions, which affect the stability and consistency of plasma processing.
Innovation Solution
A plasma processing apparatus that includes a calculation circuit to acquire and calculate an index value indicating the state of reflected waves from continuous and intermittent pulses, and a determination circuit to derive set parameters for radio-frequency power supplies, optimizing the reflection convergence time by excluding specific pulse ranges to stabilize the matching process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If radio-frequency pulses for bias are driven intermittently, then productivity is improved through pulse-driven processing, but stability deteriorates due to variations in reflection convergence time
Solution Approach 1:
The system performs preliminary actions by calculating index values for multiple set parameters in advance, identifying the optimal parameter combination that minimizes reflection convergence time variations before actual plasma processing begins. This pre-calculation and pre-optimization approach allows the system to establish stable matching conditions that can handle intermittent pulse driving without suffering from reflection convergence issues during actual processing.
Solution Approach 2:
The system implements feedback by continuously monitoring reflection convergence time and using this information to adjust and optimize set parameters. The calculation circuit calculates index values based on actual reflection characteristics, and the determination circuit uses this feedback to identify the optimal parameter combination, creating a closed-loop control system that maintains stability despite intermittent pulse operation.
2Adaptability or versatility
If matching position is adjusted frequently, then adaptability is improved to handle varying conditions, but stability deteriorates due to binarization and fluctuation in matching positions
Solution Approach 1:
The system calculates index values for multiple candidate set parameters in advance and identifies the optimal combination before processing begins. This preliminary optimization creates a predetermined matching strategy that adapts to varying conditions through pre-computed parameters rather than frequent real-time adjustments, thereby maintaining matching position stability while retaining adaptability.
Solution Approach 2:
The system dynamically selects from multiple pre-calculated set parameter combinations based on actual processing conditions. Rather than frequently adjusting matching positions during operation, the system chooses the most appropriate pre-optimized parameter set, providing adaptability through selection while maintaining stability by avoiding continuous adjustments.
Data Source
AI summary
A plasma processing apparatus performs plasma processing in a manner that first and second radio-frequency power supplies generate pulses, respectively, and a matching box controls load-side impedance of the second radio-frequency power supply, and includes: a calculation circuit that acquires power of corresponding reflected wave when the first radio-frequency power supply generates continuous pulse, and the second radio-frequency power supply generates intermittent pulse, based on different set parameters, and calculates an index value indicating the state of reflected wave; and a determination circuit that determines set parameters to be specified in the first and second radio-frequency power supplies, based on variation of each calculated index value, and derives a range to be excluded from a calculation target when the index value to be used for controlling the matcher is calculated.