Wafer Aligner Inspection Using Camera and Laser Defect Sensing
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Solution Overview
Problem
Existing semiconductor processing devices face challenges in efficiently detecting defects such as scratches and warpage on wafers during transfer and processing, due to limited space and distortion issues with camera sensors, and the need for separate inspection equipment which reduces overall process efficiency.
Innovation Solution
Integrating a camera sensor and a laser sensor in the aligner of the semiconductor processing device to capture multiple sub-images and measure distances while rotating the wafer, allowing for accurate detection of defects without additional inspection stages, using a controller to combine these images and distance measurements for comprehensive defect analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a camera sensor is used to capture wafer images for defect detection, then surface defects can be detected, but image distortion occurs and detection accuracy is reduced
Solution Approach 1:
The patent introduces a laser sensor as an intermediary measurement tool to detect wafer surface topography and warpage. The laser sensor measures distance information without the distortion issues affecting camera sensors, providing accurate topographical data as a mediator between the wafer and the detection system.
Solution Approach 2:
The patent segments the defect detection function into two separate sensing systems: a camera sensor for capturing surface images and a laser sensor for measuring distance and topography. This segmentation allows each sensor to perform its specialized function optimally without the limitations that would affect a single combined system.
2Measurement precision
If separate inspection equipment is added to detect wafer defects, then detection capability is improved, but device complexity and space requirements increase
Solution Approach 1:
The patent merges the defect detection function into the existing aligner structure. The camera sensor and laser sensor are integrated into the aligner, which already contains a stage for wafer placement and rotation capability. This combining approach adds detection capability without requiring entirely separate inspection equipment.
Solution Approach 2:
The aligner is given multi-functionality by integrating both alignment and defect detection capabilities. The same stage and rotation mechanism used for wafer alignment are also utilized for defect inspection, allowing one device to serve multiple purposes and reducing overall system complexity.
3Measurement precision
If the aligner rotates the wafer for comprehensive inspection, then inspection coverage is improved, but inspection time increases
Solution Approach 1:
The patent implements continuous rotation of the wafer during inspection, allowing the camera and laser sensors to continuously capture data across the entire wafer surface. This continuous action ensures complete inspection coverage without interruption, maximizing the efficiency of the inspection 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
Enables efficient and accurate detection of wafer defects like scratches and warpage within the limited space of the processing device, improving overall process efficiency by integrating defect inspection with alignment, reducing the need for separate inspection stages.
Implementation Method 1
a laser sensor mounted above the stage and configured to measure a distance to an upper surface of the wafer
Implementation Method 2
a lighting device mounted above the stage and configured to irradiate a partial region of the wafer with light, a camera sensor mounted above the stage and configured to image a partial region of the wafer
Data Source
AI summary
A semiconductor processing device includes a stage configured to receive a bare wafer placed thereon, a laser sensor located above the stage in a vertical direction, orthogonal to an upper surface of the bare wafer, a camera sensor located above the stage in a first direction, a lighting device radiating an imaging region imaged by camera sensor with light, and a controller, configured to rotate the bare wafer using the stage, obtain a plurality of sub-images of the bare wafer captured by the camera sensor to generate an original image of the bare ware, and detect a first defect of the bare wafer using the original image, wherein the controller is configured to detect a second defect of the bare wafer by measuring a distance between the laser sensor and the bare wafer, while rotating the bare wafer using the stage.