Retro-reflective Sheet for Wafer Detection in Rotating Substrate Processing
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Solution Overview
Problem
Existing liquid processing apparatuses face difficulties in detecting the presence or absence of substrates due to the challenge of guiding light into supply pipes installed through rotating plates, which obstructs the detection process.
Innovation Solution
A substrate processing apparatus is designed with a ring-shaped retro-reflective sheet positioned below the substrate support unit, allowing incident light to be projected and reflected, enabling detection of the substrate's presence or absence based on the intensity of the reflected light, even when a supply pipe penetrates through the rotating plate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a supply pipe penetrates through the rotating plate for liquid supply, then liquid processing can be performed, but substrate detection becomes difficult due to light guidance obstruction
Solution Approach 1:
A retro-reflective sheet is introduced as an intermediary element to facilitate light detection. The sheet reflects light back toward the detector, enabling substrate presence detection without requiring direct light guidance through the supply pipe, thus resolving the conflict between liquid supply and detection capabilities
Solution Approach 2:
The supply pipe structure is designed to serve multiple functions: it acts as both a liquid supply conduit and a support structure for the retro-reflective sheet. This multi-functionality allows the same component to enable both liquid processing and substrate detection without requiring separate dedicated structures
2Measurement precision
If light is projected for substrate detection, then substrate presence can be detected, but the supply pipe structure obstructs the light path
Solution Approach 1:
The retro-reflective sheet serves as a mediator that simplifies the light path configuration. Instead of requiring complex light guidance through the supply pipe, the sheet reflects light back toward the detector, enabling accurate substrate detection with a simpler optical configuration
Solution Approach 2:
Instead of guiding light through the supply pipe to detect substrate presence, the system inverts the approach by using the retro-reflective sheet to reflect light back toward the detector. This inversion of the light path strategy reduces structural complexity while maintaining detection accuracy
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
This solution ensures reliable detection of substrates during liquid processing, allowing the supply pipe to function for both liquid supply and detection purposes without interference, enhancing operational efficiency.
Implementation Method 1
a ring-shaped retro-reflective sheet is disposed below the substrate supported by the substrate support unit. A light projecting part configured to project incident light having a predetermined incident angle to the retro-reflective sheet from a slanted upper side, and a light receiving part configured to receive reflected light reflected in the same direction as the incident angle from the retro-reflective sheet
Data Source
AI summary
A liquid processing apparatus includes a substrate holding and rotating unit provided with a rotating plate and a substrate support unit, and a liquid supply unit. The rotating plate is connected to a rotating shaft and a central portion of the rotating shaft is exposed to outside through an opening of the rotating plate. A ring-shaped retro-reflective sheet is attached to the central portion of the rotating shaft. The central opened part of the ring-shaped retro-reflective sheet is positioned on the extended line of the central axis of the wafer holding and rotating unit. Further, a supply pipe penetrates through the central opened part of the retro-reflective sheet. Laser light is irradiated to the retro-reflective sheet from the slanted upper side, the reflected light is received by the laser light projecting/receiving part, and presence or absence of the wafer is detected by a substrate detection unit.