Lithography Pattern Measurement With Region-Specific Signal Balancing
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Solution Overview
Problem
Existing lithography processes face challenges in maintaining measurement accuracy due to variations in detection light intensity caused by reflectance differences between patterns in the same or different layers, leading to decreased productivity and measurement errors.
Innovation Solution
A measurement apparatus that adjusts the sensitivity of different image capturing regions to maintain a relative ratio of detection signal intensities within an allowable range, using a control unit to set specific image capturing regions for each pattern and adjust the image sensor's sensitivity to optimize signal intensity and reduce noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single image capturing region is used to capture multiple patterns, then the measurement process is simplified, but measurement accuracy decreases due to varying detection light intensity from reflectance differences
Solution Approach 1:
The patent divides the image capturing region into multiple separate regions, with each region dedicated to capturing a specific pattern. This segmentation allows independent optimization of detection parameters for each pattern, compensating for reflectance differences and maintaining high measurement accuracy without excessive process complexity.
Solution Approach 2:
The patent applies different detection settings and sensitivity levels to different image capturing regions based on the specific characteristics of each pattern being measured. This local quality approach ensures that each pattern is captured with optimal parameters tailored to its reflectance properties, thereby maintaining high measurement accuracy across all patterns.
2Measurement precision
If the detection sensitivity is increased to improve measurement accuracy, then measurement precision improves, but measurement time increases due to the need for multiple measurements
Solution Approach 1:
The patent performs preliminary determination of the detection signal intensity ratio between different patterns before the actual measurement. Based on this preliminary information, the system pre-adjusts the detection sensitivity and sets appropriate image capturing regions, allowing high-accuracy measurement to be achieved in a single pass without requiring multiple repeated measurements.
Solution Approach 2:
The patent dynamically adjusts detection parameters including sensitivity levels and image capturing region settings based on the determined intensity ratios of different patterns. This parameter optimization allows the system to achieve high measurement accuracy while minimizing measurement time by capturing all necessary data in a single measurement cycle.
3Measurement precision
If the detection sensitivity is adjusted to compensate for reflectance differences, then measurement accuracy improves, but device complexity increases due to additional adjustment mechanisms
Solution Approach 1:
The patent adjusts detection parameters including sensitivity and image capturing region settings based on the determined intensity ratios of different patterns. This software-based parameter optimization achieves measurement accuracy compensation without requiring additional hardware components, thereby maintaining relatively simple device structure.
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 approach allows for accurate measurement of pattern positions despite reflectance differences, enhancing productivity by reducing measurement errors and time requirements.
Implementation Method 1
an image capturing unit including a plurality of pixels which detect light from the first pattern and light from the second pattern
Data Source
AI summary
The present invention provides a measurement apparatus for measuring a position of a first pattern and a position of a second pattern provided in a target object, the apparatus including an image capturing unit including a plurality of pixels which detect light from the first pattern and light from the second pattern, and configured to form an image capturing region used to capture the first pattern and the second pattern by the plurality of pixels, and a control unit configured to adjust the image capturing unit such that a relative ratio of an intensity of a detection signal of the first pattern generated based on an output from a first image capturing region and an intensity of a detection signal of the second pattern generated based on an output from a second image capturing region falls within an allowable range.