Wafer Transfer Gripper Weight Sensing for Drop Detection
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Solution Overview
Problem
Current wafer treatment equipment cannot confirm if a wafer is held by the transport mechanism during transport, leading to delays and inefficiencies when wafers fall off, which affects processing and can render other wafers unusable.
Innovation Solution
Incorporating a wafer gripping mechanism with openable and closable hands, a rotation mechanism, and sensors that measure weight applied to the hands, allowing real-time determination of wafer presence and immediate stopping of operations if an abnormality is detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If optical sensors are used to detect wafer presence at module entrances/exits, then wafer presence can be determined at transport start and completion, but wafer presence cannot be confirmed during transport, causing delays when wafers fall off
Solution Approach 1:
A weight sensor is introduced as an intermediary element in the wafer gripping mechanism to detect wafer presence during transport. The weight sensor measures the weight of the wafer held by the gripping mechanism, providing real-time confirmation of wafer presence throughout the transport process, not just at start and completion points.
Solution Approach 2:
The patent replaces optical detection methods with a mechanical weight-based detection system. Instead of using optical sensors that can only detect wafer presence at fixed points, a weight sensor integrated into the gripping mechanism provides continuous mechanical measurement of wafer weight during transport, enabling real-time monitoring.
2Reliability
If real-time weight measurement is implemented in the wafer gripping mechanism, then wafer presence can be confirmed during transport, but the device complexity increases
Solution Approach 1:
The weight sensor is merged with the existing wafer gripping mechanism, combining the functions of wafer holding and weight measurement into a single integrated system. This reduces overall device complexity compared to adding a separate detection system, as the weight measurement capability is built into the gripping mechanism itself.
Solution Approach 2:
The wafer gripping mechanism is enhanced to perform multiple functions: it not only grips and transports wafers but also measures wafer weight through the integrated weight sensor. This multi-functionality reduces the need for separate dedicated weight measurement equipment, thereby managing device complexity.
3Loss of time
If continuous monitoring during transport is implemented, then transport errors can be detected immediately, but the measurement and control systems become more complex
Solution Approach 1:
The wafer gripping mechanism performs self-monitoring through the integrated weight sensor, automatically detecting when a wafer is missing or dropped during transport. The system serves itself by using its own structural elements (the gripping mechanism and weight sensor) to monitor its operational status, eliminating the need for external complex monitoring infrastructure.
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 rapid detection and response to transport errors, reduces downtime, and ensures accurate tracking of wafer position, improving overall processing efficiency by confirming wafer presence during transport.
Implementation Method 1
a sensor that measures a value corresponding to a weight applied to the pair of hands when the pair of hands are in a closed state
Data Source
AI summary
A cleaning and transfer equipment includes cleaning modules disposed in series, a wafer transport mechanism transporting a wafer between the cleaning modules, and a control device controlling an operation of the wafer transport mechanism. The wafer transport mechanism includes a wafer gripping mechanism gripping the wafer, a vertical moving mechanism vertically moving the wafer gripping mechanism, and an arrangement direction moving mechanism moving the wafer gripping mechanism in an arrangement direction of the cleaning modules. The wafer gripping mechanism includes a pair of hands openable and closeable, a rotation mechanism rotating the hands about a rotation shaft parallel to an opening/closing direction, and a sensor measuring a value corresponding to a weight applied to the hands when the hands are in a closed state. The control device compares measurement data of the sensor with a predetermined threshold value to determine whether the wafer is held on the hands.