Exposure Apparatus Sensor Mark Alignment for Measurement Accuracy
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Solution Overview
Problem
Conventional aerial image measurement devices suffer from measurement errors due to deviations between the center of the glass plate opening and the sensitive region of the sensor, affecting light detection and leading to inaccuracies in image performance measurements.
Innovation Solution
The exposure apparatus includes a substrate stage with a measurement device featuring substrate-side marks, where central marks are positioned at the center of the sensitive region and peripheral marks are arranged around them, allowing for accurate light detection and measurement by driving the substrate stage parallel to the optical axis, thereby reducing measurement errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a glass plate with an opening and a sensor are used in the measurement device, then the device structure is simple, but measurement errors occur due to deviation between the opening center and sensor sensitive region center
Solution Approach 1:
The measurement device uses multiple marks (central mark and peripheral marks) instead of a single opening. The central mark is positioned at the center of the sensor's sensitive region, while peripheral marks are positioned at specific locations around it. This segmentation allows the system to use the central mark for accurate light amount measurement and the peripheral marks for other measurements, eliminating the deviation error while maintaining structural simplicity.
2Ease of manufacture
If the opening center of the glass plate is used for measurement, then the device structure is simple, but measurement errors occur due to misalignment with the sensor's sensitive region center
Solution Approach 1:
Different regions of the measurement device have different functions: the central mark region is optimized for light amount measurement by positioning it at the center of the sensor's sensitive region, while peripheral mark regions are positioned at specific locations for telecentricity and overlay measurements. This local optimization ensures that each measurement function has the appropriate reference mark configuration, improving overall measurement precision without complicating the overall device structure.
3Measurement precision
If a single central mark is used for light amount measurement, then measurement accuracy is improved, but the ability to perform multiple types of measurements is reduced
Solution Approach 1:
The measurement device incorporates both a central mark and multiple peripheral marks on the same glass plate. The central mark positioned at the center of the sensor's sensitive region handles light amount measurement, while the peripheral marks positioned at specific locations enable telecentricity measurement, overlay measurement, and other measurement functions. This multi-functional design allows a single measurement device to perform multiple types of measurements with high precision.
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 configuration enhances measurement accuracy by ensuring that light is detected accurately, reducing errors in telecentricity and overlay measurements, and improving the overall performance of the exposure apparatus.
Implementation Method 1
a sensor for detecting light transmitted through a mask-side mark formed on the mask or the mask stage, the projection optical system, and the substrate-side mark, and configured to measure an amount of the light detected by the sensor
Data Source
AI summary
An exposure apparatus comprises a projection optical system for projecting a pattern of a mask, a substrate stage for holding a substrate, and a measurement device installed on the substrate stage, including a plate on which a substrate-side mark is formed, and a sensor for detecting light transmitted through a mask-side mark, the projection optical system, and the substrate-side mark, and configured to measure an amount of the light detected by the sensor. The substrate-side mark includes a central mark arranged in a center of a sensitive region of the sensor, and a peripheral mark arranged in a periphery of the central mark. The central mark is used in measurement of the light amount, including driving the substrate stage in a direction parallel to an optical axis of the projection optical system.