Microlens Shutter Array for Semiconductor Wafer Defect Detection
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Solution Overview
Problem
Current defect detection systems for semiconductor wafers face challenges in achieving high sensitivity and high throughput for all defect types due to the complexity and size of spatial filter mechanisms, as well as low aperture ratios in existing MEMS shutter arrays.
Innovation Solution
A defect detection device and method utilizing a multi-shutter device with a microlens array and shutter array configuration that condenses and controls light to form a spatial filter, allowing for high-speed and sensitive defect detection without the need for numerous mechanical filters, thereby reducing system size and increasing aperture ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a large number of spatial filters are mounted in advance to detect all defect types, then defect detection versatility is improved, but device complexity and size increase
Solution Approach 1:
The patent changes the state of the spatial filter from a mechanical selection among multiple discrete filters to a continuously adjustable optical parameter. By using a liquid crystal shutter array that can be electrically controlled to create different transmission patterns, the system achieves multiple filter configurations without physical filter changes, resolving the contradiction between versatility and complexity
Solution Approach 2:
The patent replaces the mechanical filter switching mechanism with an electrical control system. The liquid crystal shutter array is controlled by electrical signals to create different spatial filter patterns, eliminating the need for mechanical filter mounts, switches, and alignment mechanisms, thus reducing device complexity while maintaining defect detection versatility
2Adaptability or versatility
If a mechanical filter switching mechanism is used to select required filters, then adaptability is improved, but device size increases
Solution Approach 1:
The patent substitutes mechanical filter switching with an electrical control system using a liquid crystal shutter array. This eliminates the need for physical filter storage, mechanical switching mechanisms, and associated alignment systems, significantly reducing the overall device volume while maintaining the ability to select different filter configurations
3Speed
If an open and close MEMS shutter array is used for high-speed filter switching, then switching speed is improved, but aperture ratio decreases
Solution Approach 1:
The patent changes the material state and control mechanism from MEMS mechanical shutters to liquid crystal-based optical shutters. The liquid crystal shutters can be rapidly switched between transparent and opaque states using electrical signals, achieving high switching speed while maintaining a larger aperture ratio because the shutters can be made thinner and more transparent in their open state compared to mechanical MEMS shutters
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 highly sensitive and high-speed detection of various defects with reduced system size and improved aperture ratio, enhancing the detection of multiple defect types and finer defects compared to traditional methods.
Implementation Method 1
a first microlens array configured to condense parallel light transmitted through the objective lens
Implementation Method 2
a shutter array including a light transmission unit at a focus position of the first microlens array
Implementation Method 3
a second microlens array disposed on a side opposite to the first microlens array with respect to the shutter array
Implementation Method 4
an image capturing optical system configured to capture an image of scattered light generated on the wafer irradiated with light
Data Source
AI summary
A defect detection device including an illumination optical system, an image capturing optical system configured to capture an image of scattered light generated by the illumination optical system irradiating the wafer, and an image processing unit configured to process a picture of the image of the scattered light to extract a defect on the wafer. The image capturing optical system includes an objective lens, a filter unit configured to shield a part of light transmitted through the objective lens, and an imaging lens configured to form an image of light transmitted through the filter unit. The filter unit includes a first microlens array configured to condense parallel light transmitted through the objective lens, a shutter array including a light transmission unit at a focus position of the first microlens array, and a second microlens array disposed opposite to the first microlens array with respect to the shutter array.