Exposure Apparatus Stage Position Correction via Force Feedback
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Solution Overview
Problem
Existing exposure apparatuses face challenges in accurately controlling the position of a substrate stage due to deformation of the measurement device's support structure under forces like vibrations, leading to measurement errors, which are not adequately corrected by previous methods using evaluation substrates with overlapping patterns.
Innovation Solution
The exposure apparatus includes a calculation unit that calculates a correction coefficient using an evaluation substrate with multiple shot regions, each containing marks, to measure position deviations and force differences, allowing for accurate correction of the substrate stage's position control system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high rigidity structure is used to support the position measurement unit, then the position measurement precision is improved, but the structure deforms under vibration and reaction forces causing position deviation
Solution Approach 1:
The patent applies feedback by measuring the actual position deviation of the substrate stage using the position measurement unit and feeding this information back to the control system. The control unit then adjusts the substrate stage position based on the measured deviation, creating a closed-loop control system that compensates for structural deformation under vibration and reaction forces.
Solution Approach 2:
The patent changes the control parameter from ideal rigid structure assumption to actual measured position deviation. By continuously monitoring the real position of the substrate stage and comparing it with the commanded position, the system adjusts control parameters dynamically to compensate for structural deformation, transforming the rigid structure requirement into a flexible control approach.
2Measurement precision
If evaluation substrate with overlapping patterns is used to calculate correction coefficient, then position deviation can be measured, but the position deviation and force difference are too small to achieve successful calibration
Solution Approach 1:
The patent segments the evaluation substrate into multiple regions with distinct patterns, including first and second mark regions with different spatial frequencies and orientations. This segmentation creates sufficiently large position deviations and force differences when exposing different regions, enabling accurate calculation of correction coefficients for calibration.
Solution Approach 2:
The patent introduces multiple dimensions of pattern variation on the evaluation substrate, including different spatial frequencies, orientations, and positions of marks in various regions. This multi-dimensional approach generates sufficient position deviation information and force difference data across multiple dimensions, overcoming the limitation of single-dimensional overlapping patterns.
Data Source
AI summary
The present invention provides an exposure apparatus which exposes a substrate to light, the apparatus comprising a substrate stage, a position measurement unit configured to measure a position of the substrate stage, a structure configured to support the position measurement unit, a force measurement unit configured to measure a force that acts on the structure, a correction unit configured to correct a command for controlling the position of the substrate stage, based on the measurement value obtained by the force measurement unit, and a correction coefficient, and a calculation unit configured to calculate the correction coefficient based on position deviation information between adjacent shot regions in an evaluation substrate including a plurality of shot regions exposed without correction by the correction unit, and the measurement value obtained by the force measurement unit in exposing each shot region.