Wafer Aligner Notch Detection Using Rangefinder Edge Scanning
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Solution Overview
Problem
Existing wafer positioning methods often result in incorrect determination of the notch position due to overlapping with the gripper, leading to increased calibration time and irregular deformation of thin wafers, especially when using robotic arms and comparison sensors.
Innovation Solution
A wafer aligner system comprising a lifting gripper, rotating gripper, rangefinder, and control module that alternately transfers wafers between these components, using the rangefinder to detect changes in relative distance along the wafer edge to accurately determine the notch position, thereby avoiding misjudgments and reducing calibration time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a comparison sensor is used to detect the notch position, then the wafer can be positioned, but the notch may overlap with the gripper causing incorrect determination
Solution Approach 1:
The patent extracts the detection function from the gripper area by using a separate rangefinder positioned independently from the gripper. The rangefinder detects the notch position by measuring distance changes along the wafer edge, separating the detection process from the gripping process to avoid overlap interference and improve detection reliability.
2Manufacturing precision
If the wafer is gripped for calibration, then the wafer can be positioned, but thin wafers experience irregular deformation and warping
Solution Approach 1:
The patent replaces the mechanical gripping-based positioning method with an optical/range-based detection system. The rangefinder detects notch position by measuring distance variations, eliminating the need for strong mechanical gripping that causes deformation. The wafer is supported on a pallet rather than clamped, maintaining its flat shape while enabling accurate positioning.
3Measurement precision
If the notch and gripper are staggered to avoid overlap, then misjudgment is reduced, but the time for wafer calibration increases
Solution Approach 1:
The patent introduces an intermediary detection mechanism - the rangefinder - that measures notch position by detecting distance changes along the wafer edge during rotation. This intermediary method allows continuous detection without requiring specific staggered positions, enabling accurate notch identification while maintaining efficient calibration timing.
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 enhances the accuracy and efficiency of wafer positioning by accurately detecting the notch position, reducing the risk of misjudgment and deformation, and improving the overall sensing process.
Implementation Method 1
the rangefinder to detect a change in a relative distance along an edge of the wafer to determine a position of a notch of the wafer
Data Source
AI summary
Disclosed is a wafer aligner device including a platform, a lifting gripper disposed on the platform to be lifted up or lowered down relative to the platform, a rotating gripper disposed on the platform to be rotated relative to the platform, a rangefinder disposed next to the platform, and a control module. The control module is electrically connected to the lifting gripper, the rotating gripper, and the rangefinder. The control module drives the lifting gripper to be lifted up or lowered down to transfer a wafer between the lifting gripper and the rotating gripper. When the wafer is disposed on the rotating gripper, the control module rotates the rotating gripper relative to the platform and drives the rangefinder to detect a change in a relative distance along an edge of the wafer so as to determine a position of a notch of the wafer.