Multi-Wavelength Alignment Mark Measurement Device
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Solution Overview
Problem
Existing imprint techniques face challenges in accurately measuring the relative position between alignment marks on a mold and substrate due to variations in reflectance caused by different materials, patterns, and thicknesses, leading to inconsistent light detection and measurement accuracy.
Innovation Solution
A measurement device is developed with an illumination unit emitting light at multiple wavelengths to illuminate alignment marks on both the mold and substrate, a detection unit to capture light from these marks, and a processing unit to adjust the light amounts to ensure consistent detection across different types of marks, thereby improving measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single wavelength light is used to illuminate alignment marks, then the device complexity is reduced, but the measurement precision deteriorates due to varying reflectance of different mark types
Solution Approach 1:
The illumination system is segmented into multiple wavelength channels (first wavelength and second wavelength), with each wavelength specifically suited for illuminating certain types of alignment marks. This segmentation allows optimal illumination conditions for different mark types while maintaining a manageable system structure through independent wavelength control.
Solution Approach 2:
The illumination wavelength parameter is changed and optimized for different alignment mark types. By selecting appropriate wavelengths from multiple available wavelengths, the system adapts to the reflectance characteristics of various mark materials and patterns, thereby improving measurement precision without requiring complex adaptive mechanisms.
2Measurement precision
If illumination light amount is increased to improve detection sensitivity, then the detection capability is enhanced, but measurement precision deteriorates due to saturation and inconsistent detection light amounts
Solution Approach 1:
The illumination intensity parameter is independently optimized for each wavelength channel based on the specific alignment mark type being detected. By adjusting the light amount of each wavelength separately, the system prevents saturation for highly reflective marks while ensuring sufficient signal for low-reflectance marks, thereby maintaining consistent detection quality across all mark types.
Solution Approach 2:
The system incorporates feedback mechanisms to monitor detection light amounts and adjust illumination intensity accordingly. By measuring the actual detection signal levels and comparing them against optimal ranges, the control unit dynamically adjusts the illumination light amounts to maintain precision within the predetermined range.
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
The solution enhances the accuracy of relative position measurement between alignment marks by adjusting light amounts to within a predetermined range, reducing measurement errors and improving the registration of substrate and mold patterns.
Implementation Method 1
a light amount of light reflected from the marks according to the gap between the mold and the substrate changes differently depending on the wavelength
Data Source
AI summary
A measurement device for measuring a relative position between alignment marks includes an illumination unit capable of illuminating the alignment marks at a plurality of wavelengths, a detection unit that detects light from the alignment marks, a processing unit that obtain the relative position between the alignment marks, and an adjustment unit that adjusts a relative amount between light amounts of the plurality of wavelengths so that a relative value between detection light amounts of light from the alignment marks falls within a predetermined range.