Microwave Waveform Correction for Plasma Stability
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Solution Overview
Problem
Plasma processing apparatuses face challenges in maintaining stable plasma conditions due to component tolerances and wear, leading to changes in process characteristics, and existing methods require separate diagnosis recipes that decrease productivity by using different microwave settings for diagnosis and process recipes.
Innovation Solution
A plasma processing apparatus with a controller that measures and corrects the microwave waveform by calculating a correction value based on frequency spectra at different timings, allowing for continuous process recipe execution without the need for a separate diagnosis recipe, thereby reducing characteristic changes and improving productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a separate diagnosis recipe is used to measure microwave characteristics, then measurement precision is improved, but productivity deteriorates due to requiring separate diagnosis steps
Solution Approach 1:
The patent combines the diagnosis function and process execution function into a single unified process. The controller executes both diagnosis and process recipes sequentially, allowing microwave characteristic measurement to be integrated with normal production flow without requiring separate dedicated diagnosis steps, thus resolving the contradiction between measurement precision and productivity
Solution Approach 2:
The controller is designed to universally execute both diagnosis recipes and process recipes using the same microwave generation and measurement system. This multi-functional capability allows the system to perform both measurement and production tasks without requiring separate specialized systems, eliminating the productivity loss associated with separate diagnosis procedures
2Stability of the object's composition
If component tolerances and wear are not corrected, then device complexity is reduced, but plasma stability deteriorates due to characteristic changes
Solution Approach 1:
The patent implements a feedback mechanism where the controller measures microwave characteristics (travelling wave power and reflected wave power) at multiple frequencies, compares them against reference values, and automatically adjusts microwave generation parameters to compensate for component tolerances and wear. This closed-loop feedback system maintains plasma stability without requiring complex manual intervention or system redesign
Solution Approach 2:
The system dynamically changes microwave parameters (frequency, power level) based on measured characteristics and executes correction recipes that adjust these parameters to compensate for component degradation. By changing operational parameters rather than physical components, the system maintains plasma stability while avoiding increased device complexity
3Measurement precision
If frequency sweep measurement is used, then measurement precision is improved, but loss of time increases due to sequential frequency measurement
Solution Approach 1:
The controller performs frequency sweep measurements by periodically sweeping through multiple frequency points in a systematic sequence. This periodic action allows comprehensive frequency characteristic measurement to be completed efficiently by dividing the measurement task into regular intervals, reducing total measurement time while maintaining precision through systematic sampling at multiple frequencies
Solution Approach 2:
The system performs frequency characteristic measurements as preliminary actions before executing process recipes, and also performs corrections during idle periods. By preparing measurement data in advance and utilizing available time windows, the system minimizes the impact of measurements on production time while ensuring accurate frequency characteristic data is available when needed
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 apparatus effectively stabilizes plasma conditions by correcting the microwave waveform, minimizing differences between diagnosis and process recipe results, and enhancing productivity by eliminating the need for a separate diagnosis recipe.
Implementation Method 1
a microwave generator configured to generate a microwave having a center frequency, power, and a bandwidth respectively corresponding to a setting frequency, setting power, and a setting bandwidth
Implementation Method 2
a waveguide configured to guide the microwave output by the microwave generator to the antenna
Implementation Method 3
The demodulator is provided in the waveguide and is configured to measure travelling wave power and reflected wave power of the microwave for each frequency
Implementation Method 4
a plasma processing apparatus that processes a substrate with plasma
Data Source
AI summary
A controller of a plasma processing apparatus stores a frequency spectrum related to a first timing into a storage unit, controls a microwave generator to generate a microwave in correspondence to a setting frequency, setting power, and a setting bandwidth at a second timing, controls a demodulator to measure travelling wave power and reflected wave power of the microwave for each frequency, calculates the frequency spectrum related to the second timing on the basis of a measurement result from the demodulator, calculates a correction value for correcting a waveform of the travelling wave power for each frequency such that a difference for each frequency between the frequency spectrum related to the second timing and the frequency spectrum related to the first timing, stored in the storage unit, is small, and controls the microwave generator on the basis of the calculated correction value for each frequency.