Semiconductor Crack Imaging with Combined Reflected and Transmitted Light
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Solution Overview
Problem
Current defect detection systems in semiconductor manufacturing face challenges such as large equipment footprint, low inspection speed for transmitted light, and high overkill/underkill rates due to reliance on reflected light and separate image acquisition for transmitted and reflected light, which complicates defect identification and increases costs.
Innovation Solution
A system and method that simultaneously acquire reflected and transmitted light images of a workpiece using a single camera exposure, with LEDs as light sources, semi-mirrors to split light paths, and adjustable mirrors and camera positions to accommodate different workpiece sizes and orientations, allowing for improved defect differentiation and reduced overkill/underkill rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If separate inspection apparatuses are used for reflected light and transmitted light imaging, then both imaging modes can be supported, but the equipment footprint becomes large and inspection speed decreases
Solution Approach 1:
The patent combines both reflected light and transmitted light imaging capabilities into a single inspection apparatus. The illumination system includes both reflected light illumination sources and transmitted light illumination sources, allowing the same apparatus to perform both imaging modes without requiring separate equipment, thereby reducing the equipment footprint while maintaining versatility
Solution Approach 2:
The inspection apparatus is designed with multi-functional capabilities to perform both reflected light imaging and transmitted light imaging using the same camera and optical path. The system can switch between different illumination modes (reflected light from first illumination sources or transmitted light from second illumination sources) to inspect the same workpiece, making the apparatus universal and eliminating the need for multiple specialized devices
2Measurement precision
If transmitted light imaging is performed separately, then internal defects can be detected, but inspection speed becomes slow
Solution Approach 1:
The patent enables continuous simultaneous acquisition of both reflected light images and transmitted light images of the workpiece. By using multiple illumination sources that can operate concurrently and a single camera that captures both imaging modes in the same field of view, the system performs transmitted light imaging continuously without separate inspection steps, thereby maintaining high inspection speed while detecting internal defects
3Productivity
If only reflected light imaging is used, then inspection speed is fast, but overkill and underkill rates increase due to dicing marks
Solution Approach 1:
The patent segments the imaging into two complementary modes: reflected light imaging for capturing surface features and transmitted light imaging for capturing internal defect features. By analyzing both segmented imaging results together, the system can distinguish between superficial dicing marks (visible only in reflected light) and actual internal defects (visible in transmitted light), thereby reducing false positives and negatives while maintaining fast inspection speed
4Adaptability or versatility
If reflected and transmitted light images are acquired separately over time, then both imaging modes are captured, but image combination for processing becomes difficult
Solution Approach 1:
The patent performs preliminary alignment by designing the optical system such that both reflected light and transmitted light images are captured in the same field of view and with the same spatial orientation. The illumination sources and optical components are arranged so that the camera simultaneously receives both imaging modes without requiring subsequent complex registration or alignment operations, thereby simplifying image processing while maintaining the ability to capture both imaging modes
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 faster, more accurate defect detection by combining reflected and transmitted light images, reducing overkill and underkill rates, and allowing for inspection of all workpiece sides with a compact apparatus, enhancing yield management in semiconductor manufacturing.
Implementation Method 1
The first mirror is disposed to receive light from the first light source. The first mirror directs the light from the first light source at an outer surface of the workpiece.
Implementation Method 2
The second mirror is disposed to receive light from the second light source. The second mirror directs the light from the second light source at the outer surface of the workpiece.
Implementation Method 3
The first semi-mirror is disposed between the first light source and the first mirror. The first semi-mirror receives the light from the first light source that is reflected from the outer surface of the workpiece and the light from the second light source that is transmitted through the workpiece.
Data Source
Figure 1~2
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AI summary
A first light source is directed at an outer surface of a workpiece in an inspection module. The light from the first light source that is reflected from the outer surface of the workpiece is directed to the camera via a first pathway. The light from the first light source transmitted through the workpiece is directed to the camera via a second pathway. A second light source is directed at the outer surface of the workpiece 180 from that of the first light source. The light from the second light source that is reflected from the outer surface of the workpiece is directed to the camera via the second pathway. The light from the second light source transmitted through the workpiece is directed to the camera via the first pathway.