Chromatic Confocal Sensor Array for High-Speed Wafer Metrology
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Solution Overview
Problem
Current three-dimensional inspection and metrology systems for bumped wafers are inefficient due to serial data acquisition methods, leading to slower throughput, reduced sampling, and increased complexity and cost, making them incompatible with rapid scanning of large areas.
Innovation Solution
A chromatic confocal technique using a white light source with varying refractive index lenses, coupled with a sensor body of sensors arranged in rows and columns, and a controller for simultaneous 2D and 3D data acquisition, allowing for faster height measurements by focusing different wavelengths at distinct distances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If serial data acquisition methods are used for three-dimensional inspection of bumped wafers, then measurement precision can be maintained, but measurement speed and throughput are significantly reduced
Solution Approach 1:
The patent combines 2D and 3D data acquisition into a single simultaneous operation using a sensor array with multiple sensors positioned at different focal depths. Each sensor captures both lateral position and height information concurrently, merging what were previously separate serial operations into one parallel process, thereby maintaining precision while dramatically increasing throughput
Solution Approach 2:
The patent adds a focal depth dimension to the sensor array, positioning sensors at multiple z-positions to capture 3D information simultaneously. This dimensional extension allows the system to acquire height data alongside lateral position data in a single measurement pass, converting a serial 2D-then-3D process into a simultaneous 3D measurement that improves both speed and capability
2Device complexity
If serial 2D followed by 3D data acquisition is implemented, then system complexity is reduced, but measurement speed becomes significantly slower
Solution Approach 1:
The patent merges 2D and 3D acquisition functions into a single sensor array system where multiple sensors operate simultaneously at different focal depths. This consolidation eliminates the need for separate 2D and 3D scanning operations, reducing overall system complexity while achieving high-speed simultaneous 3D measurement through parallel data capture
3Reliability
If multiple scanning operations are performed to acquire both 2D and 3D data, then comprehensive inspection coverage is achieved, but total inspection time increases significantly
Solution Approach 1:
The patent enables continuous simultaneous 2D and 3D data acquisition through a single scanning operation. The sensor array continuously captures both lateral position and height information across the wafer surface in one pass, eliminating the downtime and repetition associated with multiple sequential scanning operations, thereby maintaining comprehensive coverage while minimizing inspection time
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 approach significantly increases measurement speed and throughput by enabling simultaneous 2D and 3D data acquisition, improving the reliability and reducing the complexity and cost of inspection systems.
Implementation Method 1
A refractive index of the lenses varies a focal distance of each wavelength of the white light from the white light source. Each of the wavelengths of the white light focuses at a different distance from the lenses.
Data Source
AI summary
Systems and methods for height measurements, such as those for bumps, pillars, or film thickness, can use chromatic confocal techniques. The system can include a white light source that emits white light and lenses that vary a focal distance of each wavelength of the white light from the white light source. Each of the wavelengths of the white light focuses at a different distance from the lenses. A sensor body has multiple sensors that are disposed in the sensor body in multiple rows and columns. Each of the rows and the columns has at least two of the sensors.