Laser Spectrum Waveform Calculation for Fast Pulse-by-Pulse Exposure Control
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Solution Overview
Problem
In semiconductor exposure apparatuses, the use of KrF and ArF excimer lasers results in significant chromatic aberration due to their large spectrum line widths, which can decrease resolution and necessitate the use of line narrowing modules to reduce spectrum line widths, but this process is inefficient and time-consuming, especially when calculating convolution spectrum waveforms for each pulse of laser light.
Innovation Solution
A laser system that includes a spectrometer to acquire measurement waveforms from the interference patterns of laser light and a processor to calculate convolution spectrum waveforms using a deconvolution aerial image function or Fourier transform of the instrument function, allowing for high-speed calculation of convolution spectrum waveforms without the need for real-time deconvolution, thereby increasing calculation frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If real-time deconvolution is performed for each laser pulse to calculate convolution spectrum waveform, then measurement precision is improved, but calculation time increases and productivity decreases
Solution Approach 1:
The patent performs deconvolution of the aerial image function with the instrument function in advance to create a pre-calculated convolution kernel, which is then applied to measurement waveforms without requiring real-time deconvolution. This preliminary action separates the computationally intensive deconvolution step from the measurement process, enabling high-speed calculation while maintaining precision.
Solution Approach 2:
The patent pre-calculates and stores the convolution kernel (deconvolved aerial image function) before actual measurements, so that during operation only a simple convolution operation is needed rather than full deconvolution. This prepares the computational framework in advance to eliminate time-consuming operations during production.
2Manufacturing precision
If line narrowing module is added to narrow spectrum line width, then chromatic aberration is reduced, but device complexity increases
Solution Approach 1:
The patent replaces the need for physical line narrowing modules with a computational approach. By using deconvolution of the aerial image function with the instrument function to create a convolution kernel, the system achieves chromatic aberration compensation through signal processing rather than optical hardware, thereby reducing device complexity.
Solution Approach 2:
The patent introduces a computational intermediary (the convolution kernel derived from deconvolution) that mediates between the measurement waveform and the final spectrum calculation. This mathematical intermediary enables precision control without requiring additional physical components like line narrowing modules.
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 high-speed calculation of convolution spectrum waveforms for each pulse of laser light, improving the efficiency and accuracy of laser control and reducing the time required for deconvolution, thus enhancing the resolution and manufacturing speed in electronic device production.
Implementation Method 1
acquire a measurement waveform from an interference pattern of laser light output from the laser system
Data Source
AI summary
A laser system connectable to an exposure apparatus includes a spectrometer configured to acquire a measurement waveform from an interference pattern of laser light output from the laser system, and a processor configured to calculate a convolution spectrum waveform using the measurement waveform and a first intermediate function obtained through a process of deconvolution of an aerial image function of the exposure apparatus with an instrument function of the spectrometer.