RF Harmonic Calibration for Accurate Nonsinusoidal Waveform Control
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Solution Overview
Problem
Existing plasma processing systems face challenges in accurately measuring and controlling nonsinusoidal waveforms due to inaccuracies and unreliability of wideband sensors, particularly in high-performance memory and logic device fabrication, which requires precise etching of high aspect ratio features.
Innovation Solution
A system is developed that includes a RF generator outputting a nonsinusoidal signal, wideband sensors to measure voltage and current, and a controller that determines and calibrates harmonic components of the waveform using Fourier analysis and a chain matrix, enabling precise control of active and reactive power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If wideband sensors are used to measure nonsinusoidal waveforms, then measurement bandwidth is improved, but measurement precision deteriorates due to intermodulation distortion and sensor inaccuracies
Solution Approach 1:
The patent segments the nonsinusoidal waveform measurement into multiple sinusoidal harmonic components. By decomposing the complex waveform into individual harmonics and measuring each separately, the system achieves accurate measurement of each component while maintaining overall waveform measurement capability. This segmentation approach allows precise control of each harmonic's magnitude and phase without the intermodulation distortion that affects direct wideband measurement.
Solution Approach 2:
The patent introduces an intermediary computational process that uses Fourier analysis and chain matrix calculations to process sensor outputs. Rather than directly measuring the nonsinusoidal waveform with wideband sensors, the system uses these sensors to capture individual harmonic components and then reconstructs the complete waveform through mathematical computation, eliminating direct measurement errors.
2Manufacturing precision
If harmonic components are calibrated using Fourier analysis and chain matrix, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent implements a feedback control system where the controller continuously monitors the actual harmonic components of the nonsinusoidal waveform and adjusts the RF generator settings accordingly. By using Fourier analysis to measure actual waveforms and comparing them with target waveforms, the system provides real-time feedback to maintain precise etching control, compensating for variations in the plasma process.
Solution Approach 2:
The patent changes the control parameters from direct voltage/current control to harmonic component control. By controlling the magnitude and phase of individual harmonic components rather than the overall waveform directly, the system achieves more precise control over the nonsinusoidal waveform shape, enabling better etching precision through parameter optimization.
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
This system provides accurate and repeatable measurement and control of nonsinusoidal waveforms, enhancing the precision of plasma processing, especially in high aspect ratio feature etching, by minimizing intermodulation distortion and improving etch rate and profile control.
Implementation Method 1
at least one wideband sensor configured to measure at least one of a voltage and a current of the nonsinusoidal signal
Implementation Method 2
determine an uncalibrated value at each of a number of harmonic components of the waveform based on a Fourier analysis of the waveform
Implementation Method 3
generate a calibrated value at each of the number of harmonic components based on the corresponding uncalibrated value and a frequency response of the at least one wideband sensor
Implementation Method 4
a RF generator configured to output a nonsinusoidal signal to a load
Implementation Method 5
The nonsinusoidal carrier signal may be at least one of a rectangular or piecewise linear waveform. The RF generator may be controlled to pulse the carrier signal
Data Source
AI summary
A power supply system includes a RF generator configured to output a nonsinusoidal signal to a load, at least one wideband sensor configured to measure at least one of a voltage and a current of the nonsinusoidal signal, and a controller coupled to the RF generator. The controller is configured to receive a waveform associated with the nonsinusoidal signal from the at least one wideband sensor, determine an uncalibrated value at each of a number of harmonic components of the waveform, and generate a calibrated value at each of the number of harmonic components based on the corresponding uncalibrated value and a frequency response of the at least one wideband sensor. Other example power supplies, computer-readable mediums, and controllers for RF generators are also disclosed.