Curved Diffuser Illumination for Wafer Edge Imaging
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Solution Overview
Problem
Current semiconductor wafer inspection systems face challenges in effectively imaging and detecting defects on the rounded edges of wafers, particularly due to the complexity and sensitivity of modern semiconductor devices, which require precise and uniform illumination across curved surfaces.
Innovation Solution
A compact system incorporating a curved diffuser with multiple light sources and a sensor, integrated into a miniaturized format, provides uniform illumination and imaging of rounded wafer edges from various angles, allowing for the detection of defects on beveled or curved surfaces, including a positioning mechanism for adjustable imaging and a support structure for the light sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conventional optical inspection system is used for wafer edge imaging, then the system can detect defects, but the system size is large and cannot provide uniform illumination over curved surfaces
Solution Approach 1:
The patent employs a curved diffuser with a spherical or dome-shaped internal surface that matches the curvature of the wafer edge. This curved geometry enables uniform light distribution across the rounded wafer periphery while maintaining a compact system footprint. The diffuser's curved surface scatters light from multiple LEDs to achieve homogeneous illumination of the curved wafer edge region.
Solution Approach 2:
The patent integrates multiple functional components into a nested compact structure. The sensor is positioned within the curved diffuser, which itself is integrated with multiple LED light sources. This nested arrangement allows the entire illumination and detection system to be miniaturized while maintaining effective wafer edge imaging capabilities.
2Adaptability or versatility
If multiple light sources are used to illuminate the wafer edge from various angles, then comprehensive defect detection is achieved, but the device complexity increases
Solution Approach 1:
The curved diffuser serves multiple functions simultaneously: it acts as a light scattering element, a structural support for multiple LEDs, a positioning fixture for the sensor, and a geometric adapter to match the wafer's curved edge. This multi-functional design achieves comprehensive multi-angle illumination and detection without proportionally increasing system complexity.
Solution Approach 2:
The patent combines multiple LED light sources, the curved diffuser structure, and the sensor into a single integrated imaging head. This merging of components achieves versatile multi-angle wafer edge imaging while minimizing the overall device complexity through unified design and compact integration.
3Device complexity
If a compact sensor format is used, then the system size is reduced, but the imaging precision may be compromised
Solution Approach 1:
The patent positions the compact sensor at an optimized location within the curved diffuser structure, specifically at the focal region where scattered light from the wafer edge converges. This local optimization of sensor placement compensates for the small sensor size and maintains high imaging precision despite the compact overall system format.
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 enables comprehensive and precise imaging of wafer edges, detecting defects such as chips, cracks, and chemical residues, improving yield by ensuring fault-free semiconductor devices through enhanced inspection capabilities.
Implementation Method 1
a curved diffuser having an internal surface for positioning towards the rounded edge of the sample... so that the diffuser outputs uniform light over the rounded edge of the sample at a plurality of incident angles
Implementation Method 2
a curved diffuser having an internal surface for positioning towards the rounded edge of the sample... so that the diffuser outputs uniform light
Implementation Method 3
a sensor for receiving light scattered from the rounded edge of the sample in response to the incident light and generating a detected signal for generating an image
Data Source
AI summary
Disclosed are methods and apparatus for imaging a rounded edge of a sample, such as a wafer with a beveled edge. In one embodiment, the system includes a curved diffuser having an internal surface for positioning towards the rounded edge of the sample and an external surface opposite the internal surface and light sources for generating a plurality of illumination beams adjacent to a plurality of positions on the external surface of the diffuser so that the diffuser outputs uniform light onto the rounded edge of the sample at a wide range of incident angles. The system further includes a sensor for receiving light scattered from the rounded edge of the sample in response to the incident light and generating a detected signal for generating an image. These elements are partially or entirely integrated into a compact assembly.