Chromatic Confocal Area Sensor Eliminates Mechanical Scanning
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Solution Overview
Problem
Current 3D measurement systems in semiconductor manufacturing, such as chromatic confocal sensors, are slow and costly due to mechanical movement requirements, which reduce accuracy and throughput, and often compromise on resolution.
Innovation Solution
A 3D measurement system utilizing a broadband light source, a microlens array, and a tunable color filter to focus and filter light, eliminating mechanical movement by using longitudinal chromatic aberration and independent XY and Z resolution, allowing for high-resolution 3D reconstruction without mechanical scanning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If mechanical movement is used to scan the workpiece in chromatic confocal systems, then the measurement coverage is improved, but the measurement speed and accuracy deteriorate
Solution Approach 1:
The patent replaces the mechanical scanning system with an optical field scanning approach. Instead of moving the sensor or workpiece mechanically, the invention uses a tunable color filter to scan wavelengths and a microlens array to perform parallel optical measurements across the workpiece surface, eliminating mechanical movement while maintaining full measurement coverage.
Solution Approach 2:
The patent divides the measurement task into parallel segments using a microlens array. Each microlens measures a specific point on the workpiece simultaneously, creating multiple measurement channels that operate in parallel. This segmentation allows full area coverage without mechanical scanning, as all points are measured at once for each wavelength.
2Area of stationary object
If mechanical movement is used to scan the workpiece in chromatic confocal systems, then the measurement coverage is improved, but the measurement accuracy deteriorates due to vibrations
Solution Approach 1:
The patent eliminates mechanical movement entirely by using optical field scanning. The microlens array performs parallel optical measurements across the workpiece while the tunable color filter scans wavelengths electronically. This substitution of mechanical scanning with optical field manipulation eliminates vibrations and improves measurement precision while maintaining full area coverage.
3Productivity
If an array of point sources and pinholes is used to eliminate mechanical movement, then the measurement speed is improved, but the resolution deteriorates due to multiplexing compromises
Solution Approach 1:
The patent uses a microlens array to segment the measurement field into multiple parallel measurement channels. Each microlens focuses light from a specific point on the workpiece to a corresponding detector element, enabling simultaneous measurement of multiple points without multiplexing. This segmentation maintains both high measurement speed and high resolution.
Solution Approach 2:
The patent adds a wavelength dimension to the measurement by using a tunable color filter. Instead of multiplexing spatial information on a 2D sensor (which compromises resolution), the invention uses the spectral dimension to encode depth information. Each spatial point has its own measurement channel, and the wavelength tuning provides the third dimension of measurement without affecting spatial resolution.
4Area of stationary object
If a galvo mirror is used to sweep the projected point over the workpiece, then the measurement coverage is improved, but the system complexity and measurement time increase
Solution Approach 1:
The patent replaces the galvo mirror mechanical scanning system with a static microlens array. Instead of using a moving mirror to sweep a single point across the workpiece, the invention uses a fixed array of microlenses to illuminate and detect from multiple points simultaneously. This eliminates the galvo mirror and its associated complexity while achieving full measurement coverage through parallel optical paths.
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 achieves high-resolution 3D reconstruction with improved accuracy and repeatability, faster measurement times, and the ability to skip non-relevant data areas, enhancing semiconductor manufacturing efficiency.
Implementation Method 1
The microlens array focuses the light beam to a plurality of points in a focal plane of the microlens array
Implementation Method 2
The microlens array also is configured as a spatial filter for the light beam that is reflected from the workpiece on the stage thereby only passing the light beam that is in focus at the workpiece on the stage
Implementation Method 3
The lens system is configured to provide longitudinal chromatic aberration whereby different wavelengths are imaged at different distances from the lens system
Implementation Method 4
The tunable color filter is configured to narrow the light beam to a band at a central wavelength
Implementation Method 5
a broadband light source that generates a light beam
Data Source
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AI summary
3D measurements of features on a workpiece, such as ball height, co-planarity, component thickness, or warpage, are determined. The system includes a broadband light source, a microlens array, a tunable color filter, a lens system, and a detector. The microlens array can focus a light beam to a points in a focal plane of the microlens array. The tunable color filter can narrow the light beam to a band at a central wavelength. The lens system can provide longitudinal chromatic aberration whereby different wavelengths are imaged at different distances from the lens system.