Measuring Device with Selective Diffraction for Alignment Accuracy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing exposure technologies face challenges in accurately measuring the position of existing patterns on photosensitive substrates, which is crucial for aligning light and dark patterns during exposure processes.
Innovation Solution
A measuring device is developed, comprising an illumination system, an image formation system, a diffracted light restricting part, and an imaging part. This device radiates light to a measuring target object, forms a conjugate plane optically conjugated with the object plane, restricts diffracted light to pass specific orders, and images a periodic light and dark pattern formed by the diffracted light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a position measurement optical system images an alignment mark to measure the position of an existing pattern, then the position can be measured, but wave aberrations in the optical system reduce measurement accuracy
Solution Approach 1:
The patent extracts only the necessary diffracted light components (first and second diffracted light) from the complex light field, blocking other diffracted light rays. This selective extraction eliminates wave aberration effects from higher-order diffracted light while preserving the essential information needed for accurate position measurement.
Solution Approach 2:
The patent applies local quality by selectively allowing specific diffracted light rays to pass through the diffracted light blocking part while blocking others. This creates a localized optical path that is optimized for measurement accuracy by permitting only the diffracted light components that do not suffer from wave aberrations.
2Loss of information
If multiple diffracted light rays are used to image the periodic pattern, then the imaging process captures more information, but wave aberrations in the optical system degrade measurement accuracy
Solution Approach 1:
The patent extracts only the essential diffracted light components (first and second diffracted light) from the complex light field, blocking other diffracted light rays. This selective extraction eliminates wave aberration effects from higher-order diffracted light while preserving the essential information needed for accurate position measurement.
Solution Approach 2:
The patent converts the potentially harmful effect of multiple diffracted light rays (which carry wave aberration information) into a benefit by selectively blocking them. The diffracted light blocking part transforms the complex multi-ray field into a simplified two-ray field that provides cleaner measurement information, turning what could be a source of error into a means of improving measurement quality.
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 measuring device achieves accurate position measurement of marks with periodic structures, reducing the impact of wave aberrations and allowing for precise alignment of light and dark patterns during exposure, thereby enhancing the overall exposure process accuracy.
Implementation Method 1
a diffracted light restricting part configured to restrict at least some of a plurality of rays of diffracted light from the measuring target object
Implementation Method 2
an image formation system configured to form a conjugate plane optically conjugated with the object plane
Implementation Method 3
an imaging part disposed on the conjugate plane and configured to image a periodic light and dark pattern formed by the first diffracted light and the second diffracted light
Data Source
AI summary
A measuring device includes an illumination system configured to radiate light to a measuring target object located on an object plane, an image formation system configured to form a conjugate plane optically conjugated with the object plane, a diffracted light restricting part configured to restrict at least some of a plurality of rays of diffracted light from the measuring target object and to pass a first diffracted light and a second diffracted light different from the first diffracted light among the plurality of rays of diffracted light, and an imaging part disposed on the conjugate plane and configured to image a periodic light and dark pattern formed by the first diffracted light and the second diffracted light.