Wafer Alignment Device for Overlay Measurement
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Solution Overview
Problem
Conventional overlay measurement devices face challenges in accurately and efficiently calibrating the position of semiconductor wafers due to decreasing feature sizes and increasing overlay requirements, necessitating more data points for improved accuracy.
Innovation Solution
A substrate alignment device featuring state detection units and a multidimensional robot arm that adjusts the substrate's position based on detected edge positions, combined with a rail structure and optical system for precise alignment and mark detection, allowing for efficient overlay measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional optical imaging or scanning inspection is used to measure relative positional deviation between marks, then overlay measurement can be performed, but it takes 0.5 to 1 second to position marks to center and capture image, which is too slow for high-speed production requirements
Solution Approach 1:
The system performs preliminary wafer calibration by detecting edge positions and calculating transformation parameters (translation, rotation, scaling) before the actual overlay measurement. This pre-positioning action ensures that subsequent mark measurements can be performed rapidly without repeated positioning operations, thus improving measurement speed while maintaining accuracy
Solution Approach 2:
The invention replaces the conventional mechanical/optical positioning system with an automated robot arm system that uses vision guidance and pre-calculated transformation parameters. The robot arm can rapidly position the wafer based on electronic control signals rather than manual or slow optical positioning, significantly increasing measurement speed while maintaining precision through automated feedback control
2Measurement precision
If more data points are taken to improve accuracy of overlay measurements, then measurement precision improves, but measurement time increases
Solution Approach 1:
The system performs wafer calibration and edge detection on a subset of the wafer perimeter (using 4 state detection units at quadrilateral vertices) rather than scanning the entire surface. This partial action provides sufficient calibration data to calculate transformation parameters quickly, enabling accurate overlay measurement without the time cost of complete surface scanning
Solution Approach 2:
The edge detection and calibration operations are performed as preliminary steps before the actual overlay measurement. By pre-establishing the wafer position and orientation through edge detection, the system determines the optimal measurement locations and reduces the number of data points needed during the subsequent overlay measurement phase, thus maintaining accuracy while reducing total measurement time
3Measurement precision
If wafer position calibration is performed to ensure accuracy of overlay measurements, then measurement precision improves, but additional time is required for calibration operations
Solution Approach 1:
The system merges the calibration operations with the measurement process by using the same robot arm and detection systems for both edge detection/calibration and subsequent overlay measurement. The calibration data is immediately used to guide the measurement process, eliminating separate calibration and measurement phases, thus reducing total time while maintaining accuracy
Solution Approach 2:
Wafer calibration through edge detection is performed as a preliminary action that establishes transformation parameters (translation, rotation, scaling) before overlay measurement. These pre-calculated parameters are then used to rapidly position and orient the wafer for measurement, eliminating the need for repeated positioning operations during measurement and thus reducing calibration time impact on overall process
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 enables high-speed and accurate calibration of substrates, reducing the time required for overlay measurements and improving the accuracy of subsequent overlay operations.
Implementation Method 1
the photo sensor includes a light source for irradiating light onto the substrate and a light receiver for receiving light reflected from the irradiated substrate
Data Source
AI summary
A substrate alignment device includes a plurality of state detection units, each of which is configured to move from a standby position to a detection position for detecting a positional state of a substrate and return back from the detection position back to the standby position, and a multidimensional robot arm configured to receive and support the substrate, transfer the substrate to a substrate detection site, and adjust the substrate in at least one orientation or position according to the detected positional state of the substrate to position the substrate to a target position for overlay mark measurements.