Illumination Field Position Correction in Projection Exposure Apparatus
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Solution Overview
Problem
Projection exposure apparatuses for microlithography often experience irregularities in the dose distribution on wafers due to positional changes of the illumination field during scanning, leading to inaccuracies in the intended dose distribution.
Innovation Solution
A method that involves measuring positional changes of the illumination field along the scanning axis and correcting the dose distribution by modifying operational parameters such as radiation intensity or scanning speed to maintain a consistent dose distribution on the wafer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the illumination field position is monitored and operational parameters are modified to correct dose distribution, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The system implements a feedback mechanism where the actual illumination field position is measured during scanning and this information is fed back to the control device. The control device then modifies operational parameters (scanning speed or radiation intensity) based on the measured deviations to correct dose distribution inaccuracies, thereby resolving the contradiction between improved precision and increased complexity through intelligent control
Solution Approach 2:
The invention dynamically changes operational parameters (scanning speed v or radiation intensity I) in response to measured illumination field position deviations. By adjusting these parameters in real-time, the system compensates for positional drift and maintains accurate dose distribution without requiring fundamental redesign of the exposure apparatus
2Manufacturing precision
If operational parameters are modified in real-time to correct illumination field position, then manufacturing precision is improved, but productivity decreases
Solution Approach 1:
The system dynamically adjusts operational parameters during the exposure process rather than using static settings. The scanning speed or radiation intensity is modified in real-time based on illumination field position measurements, allowing the system to maintain precision while adapting to changing conditions without complete re-exposure
Solution Approach 2:
By changing operational parameters (scanning speed v or intensity I) during the exposure process based on real-time feedback, the system corrects dose distribution errors without stopping the exposure process. This dynamic parameter adjustment maintains productivity while improving precision
Data Source
AI summary
A method is provided for controlling a projection exposure apparatus for microlithography, embodied as a scanner, in the exposure operation, in which a reticle is moved along a scanning axis with respect to a frame of the projection exposure apparatus such that the reticle is scanned by an illumination field radiated thereon, and the radiation of the illumination field is guided onto a wafer after interaction with the reticle in order to generate a desired dose distribution on the wafer. The method comprises the following steps: measuring positional changes of the illumination field in the direction of the scanning axis with respect to the frame of the projection exposure apparatus, and correcting the influence of a measured positional change of the illumination field on the dose distribution on the wafer by modifying at least one operational parameter of the projection exposure apparatus.