FOUP Mapping Cameras for Thin Substrate State Detection
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Solution Overview
Problem
Existing load port systems struggle to accurately detect the accommodation states of thin substrates, such as those with a thickness of about 0.2 mm, without increasing manufacturing costs, especially when detecting overlapped or crossed states, due to the need for high-resolution imaging and narrow viewing angles.
Innovation Solution
A mapping device with a combination of a low-magnification camera with a wide horizontal angle and a high-magnification camera with a narrow angle is used, along with a controller to analyze images from both cameras, allowing detection of both doubled and crossed states while reducing costs by avoiding the need for high-resolution imaging devices and dedicated movement mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If imaging magnification is increased to detect thin substrates, then detection precision of substrate thickness is improved, but horizontal angle of view becomes narrower making it impossible to image the entire substrate
Solution Approach 1:
The imaging task is segmented into two parts: a first imaging device captures the entire substrate at low magnification to detect crossed states, while a second imaging device captures a局部 region at high magnification to detect doubled states. This segmentation allows each device to specialize in one aspect, resolving the contradiction between wide coverage and high precision.
2Measurement precision
If high-resolution imaging part is used to detect doubled state and crossed state with one mapping sensor, then detection capability is improved, but manufacturing cost increases
Solution Approach 1:
The system segments the detection function into two imaging devices with different resolutions. The first imaging device uses a lower-resolution sensor for wide-area coverage, while the second uses a higher-resolution sensor only for局部 detailed inspection. This segmentation reduces the total pixel count required compared to using a single high-resolution device, lowering manufacturing costs.
Solution Approach 2:
High imaging quality is applied locally only where needed (for detecting doubled states in a small region), while other areas use lower quality imaging. This local quality approach optimizes resource allocation, using high-resolution capability only when necessary rather than across the entire substrate area.
3Adaptability or versatility
If dedicated device for moving imaging device is provided, then imaging flexibility is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The imaging device is merged with the door assembly, utilizing the door's inherent movement capability to position the imaging device. This combination eliminates the need for a separate dedicated positioning mechanism, reducing device complexity while maintaining imaging flexibility through the door's opening and closing motion.
Data Source
AI summary
The load port includes a FOUP configured to accommodate a plurality of substrates in multiple stages, cameras configured to image each of the substrates accommodated in the FOUP and including a low-magnification camera with a wide horizontal angle of view and a high-magnification camera with a narrow horizontal angle of view, and a CPU configured to detect the accommodation state of each of the substrates based on the imaging data acquired from the low-magnification camera and the high-magnification camera, respectively.