Substrate Pre-Alignment With Fish Eye Edge Detection
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Solution Overview
Problem
There is a growing need for accurate and fast alignment of substrates within substrate evaluation systems, particularly during the load lock pressure equalization process, where time-consuming alignment procedures can hinder efficiency.
Innovation Solution
A substrate alignment system that includes an illumination unit to illuminate the entire edge of a substrate, a sensing unit with a fish eye lens to capture the entire edge even when misaligned, and a processing circuit to determine misalignment and execute correction operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional alignment systems are used, then alignment accuracy can be achieved, but the alignment process takes too much time and reduces system throughput
Solution Approach 1:
The alignment operation is performed in advance during the load lock pressure equalization process, which occurs before the substrate enters the evaluation chamber. By executing alignment preliminarily when time is available, the system avoids time-consuming alignment operations during critical evaluation phases, thereby maintaining both high alignment accuracy and system throughput.
Solution Approach 2:
The fish eye lens captures an excessive field of view that covers the entire substrate edge even when misaligned, rather than requiring precise positioning. This partial action of capturing more information than strictly necessary allows the system to achieve accurate alignment measurements without requiring time-consuming precise positioning procedures.
2Measurement precision
If the sensing unit requires precise substrate positioning, then measurement accuracy improves, but the alignment process becomes slower and less efficient
Solution Approach 1:
The sensing unit is designed to capture the entire substrate edge even when misaligned, using a fish eye lens that provides an excessive field of view. This approach allows accurate edge detection without requiring the substrate to be precisely positioned beforehand, significantly reducing alignment time while maintaining measurement precision.
Solution Approach 2:
The system changes the optical parameters by using a fish eye lens with a wide field of view instead of a conventional lens. This parameter change allows the sensing unit to capture the entire substrate edge in a single frame even when misaligned, eliminating the need for time-consuming iterative positioning while maintaining edge detection accuracy.
3Device complexity
If a conventional lens is used in the sensing unit, then the system structure is simpler, but the entire substrate edge cannot be captured when misaligned
Solution Approach 1:
The fish eye lens uses a curved optical design that provides a wide field of view, allowing the entire substrate edge to be captured even when misaligned. This curved optical path enables the system to tolerate substrate misalignment while maintaining the ability to detect edge positions accurately, improving adaptability without significantly increasing overall system complexity.
Solution Approach 2:
The system changes the optical field of view parameter by implementing a fish eye lens that provides a wide-angle view. This parameter change enables the sensing unit to capture the entire substrate edge regardless of misalignment, significantly improving adaptability to misaligned substrates while the lens integration keeps the added complexity minimal.
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 system achieves highly accurate alignment without introducing significant delays, allowing alignment to be performed during the load lock pressure equalization process, thus enhancing the throughput of substrate evaluation systems.
Implementation Method 1
a sensing unit having a field of view that covers the entire edge of the substrate even when the substrate is misaligned, the sensing unit includes a sensor that is preceded by a fish eye lens
Data Source
AI summary
A substrate alignment system that includes (i) an illumination unit that is configured to illuminate an illuminated region that comprises an entire edge of a substrate; (ii) a sensing unit having a field of view that covers the entire edge of the substrate even when the substrate is misaligned, the sensing unit includes a sensor that is preceded by a fish eye lens, the sensor is configured to generate detection signals of the entire edge of the substrate; and (iii) a processing circuit that is configured to process the detection signals and determine whether the substrate is misaligned. A determining that the substrate is misaligned triggers an execution of one or more misalignment correction operation for aligning the substrate.