Optical Cassette Object Detection Using Dual-Depth Light Blocking
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Solution Overview
Problem
Conventional processing apparatuses cannot reliably determine whether a cassette stores a wafer alone or a frame unit, leading to improper selection of transfer means, especially when the cassette is in a closed condition, such as in an FOUP cassette.
Innovation Solution
A determining apparatus with first and second detecting means, each comprising a light transmitting and receiving portion, is used to differentiate between a wafer and a frame unit by blocking light transmission based on the object's shape, allowing for accurate identification before loading into a processing apparatus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single load port is designed to accommodate both wafer-only cassettes and frame unit cassettes, then the device complexity is reduced and adaptability is improved, but the ability to accurately determine the object type stored in the cassette deteriorates
Solution Approach 1:
The detection system is segmented into multiple detection positions (first detection position and second detection position) along the insertion direction. Each position detects different characteristics of the stored object, enabling accurate identification of object type even in a universal load port configuration.
Solution Approach 2:
The detection approach transitions from single-point detection to multi-point detection along the insertion direction. By adding the depth dimension (insertion direction) to the detection scheme, the system can distinguish between wafer-only and frame unit cassettes based on how light is blocked at different depths.
2Reliability
If the cassette closing mechanism is used to protect the wafer from dust, then the reliability of wafer protection is improved, but the ease of visual inspection of the stored object deteriorates
Solution Approach 1:
The manual visual inspection method is replaced with an automated optical detection system. Light transmitting and receiving portions automatically detect object type by measuring light blockage characteristics, eliminating the need for operators to visually inspect through the opening mechanism.
Solution Approach 2:
The detection system performs automatic object identification without requiring operator intervention. The light-based detection mechanism autonomously determines whether a wafer or frame unit is stored, and this information is provided to the control unit for automatic processing.
3Reliability
If conventional detection methods are used in a closed cassette, then the reliability of object identification is improved, but the ease of operation deteriorates due to manual intervention requirements
Solution Approach 1:
The detection system autonomously identifies objects within closed cassettes using optical detection. The light transmitting and receiving portions automatically detect and differentiate between wafers and frame units without requiring operators to open or manually inspect the cassettes.
Solution Approach 2:
Manual visual inspection and physical handling are replaced with non-contact optical detection. The light-based system penetrates or detects around the closing mechanism to identify stored objects, eliminating the need for mechanical opening and manual examination.
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
Enables reliable determination of the object type within the cassette, ensuring appropriate transfer means are used, even when the cassette is closed, thereby improving operational efficiency and reducing human error.
Implementation Method 1
light transmitted from the light transmitting portion of the first detecting means is blocked by the object and does not reach the light receiving portion of the first detecting means
Implementation Method 2
light receiving portion spaced from each other by a predetermined distance in a horizontal direction
Data Source
AI summary
Apparatus determines whether a stored object is a wafer alone or a frame unit formed by uniting the wafer and a ring frame. The apparatus includes first and second detecting units, the second detecting unit being stored more shallowly than the first detecting unit. The apparatus determines whether light transmitted by the first detecting unit is blocked by the object and does not reach a light receiving portion of the first detecting unit. When light transmitted from the second detecting unit is blocked by the object and does not reach a light receiving portion of the second detecting unit, the apparatus determines that the object is the frame unit, whereas when the light transmitted from the second detecting unit is not blocked by the object and reaches the light receiving portion of the second detecting unit, the apparatus determines that the object is the wafer.