Capacitive Probe Calibration for Substrate Impedance
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Solution Overview
Problem
Existing probe systems for capacitive height sensing measurements in silicon photonics coupling techniques fail to accurately account for dielectric and resistivity properties of devices under test (DUTs) and substrates with varied material properties, leading to inaccuracies in distance calculations.
Innovation Solution
A probe system with a capacitive displacement sensor and a controller that calculates layer impedance magnitudes of substrate layers, measures impedance, and adjusts for material properties to generate calibrated capacitive height measurements, improving accuracy by accounting for the impedance of the substrate structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If general material properties are used for capacitive height sensing measurements, then the measurement process is simple, but the measurement precision is poor due to not accounting for varied dielectric and resistivity properties of DUT structures and substrates
Solution Approach 1:
The system performs preliminary calibration by measuring the impedance magnitude of the substrate structure before conducting capacitive height sensing measurements. This pre-measurement of substrate impedance characteristics allows the system to compensate for varied dielectric and resistivity properties, thereby improving measurement precision without adding significant operational complexity during the actual sensing process
Solution Approach 2:
The system uses the measured impedance magnitude as feedback to adjust and calibrate the capacitive height sensing measurements. By comparing the actual impedance measurement with expected values based on substrate architecture, the system can compensate for material property variations and improve measurement accuracy dynamically
2Measurement precision
If impedance measurement and calibration steps are added to account for substrate material properties, then measurement precision improves, but the measurement process becomes more complex
Solution Approach 1:
The system combines the impedance measurement and capacitive height sensing measurements into a single integrated process. By using the same capacitive displacement sensor to perform both functions, the system eliminates the need for separate measurement devices and reduces overall process complexity despite adding calibration steps
Solution Approach 2:
The capacitive displacement sensor is designed to serve multiple functions: it can measure both impedance magnitude and capacitive height. This multi-functionality allows the system to perform substrate characterization and height sensing with a single device, improving measurement precision while minimizing the increase in process complexity
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 solution provides more accurate capacitive height measurements by accounting for the material properties of the substrate, enhancing the precision of distance calculations and improving the alignment between optical fibers and DUTs, thereby optimizing power transfer and test accuracy.
Implementation Method 1
capacitive height sensing measurements to determine a separation distance between the DUT and the optical fiber
Implementation Method 2
do not account for the dielectric and resistivity properties of DUT structures and/or substrates with varied material properties
Implementation Method 3
calculating, with the controller and based, at least in part, on the height calibration structure architecture, a layer impedance magnitude of each substrate layer
Data Source
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AI summary
Probe systems and methods for calibrating capacitive height sensing measurements. A probe system includes a probe assembly with a probe support body that supports a capacitive displacement sensor that terminates in a sensing tip relative to a substrate and that is configured to generate an uncalibrated capacitive height measurement. A method of utilizing the probe system to generate a calibrated capacitive height measurement includes receiving a height calibration structure architecture; calculating a layer impedance magnitude of each substrate layer of the height calibration structure; and calculating a total layer impedance magnitude of the height calibration structure. The method further includes measuring a measured impedance magnitude and calculating the calibrated capacitive height measurement.