Optical MOSFET Degradation Sensing for In-Situ Threshold Drift Monitoring
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Solution Overview
Problem
Existing methods for measuring MOSFET device degradation, such as those used in solar or automotive inverters, are difficult due to the need for complex electronics, require circuit interruption, and struggle with high-frequency gate signals that trigger degradation mechanisms, making it challenging to monitor threshold voltage shifts accurately.
Innovation Solution
An optical device degradation sensor, such as a photodetector, is integrated with the MOSFET to measure photonic emissions from carrier recombination at the semiconductor-insulator interface, allowing in-situ monitoring of threshold voltage drift by analyzing light intensity and spectrum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If threshold voltage is measured by removing MOSFET from application circuitry, then measurement can be performed, but circuit operation must be interrupted and disassembly required
Solution Approach 1:
The patent replaces electrical measurement methods with optical detection. A photodetector senses light emitted during carrier recombination at the semiconductor-insulator interface, converting the measurement from an electrical process to an optical one. This allows threshold voltage monitoring without electrical contact or circuit interruption, resolving the contradiction between measurement capability and operational continuity.
Solution Approach 2:
The patent introduces light as an intermediary medium between the MOSFET and the detection system. The photodetector detects photons emitted during carrier recombination, using light as a mediator to transfer information about threshold voltage changes without requiring direct electrical connection or circuit disassembly, thus enabling continuous monitoring.
2Measurement precision
If miller plateau voltage measurement method is used, then threshold voltage can be measured during application, but complex electronics and computations are required
Solution Approach 1:
The patent replaces complex electrical measurement circuits with a simple photodetector-based optical system. Instead of measuring miller plateau voltage through complex electronics and computations, the system uses optical detection of carrier recombination light, significantly reducing measurement system complexity while maintaining accuracy.
Solution Approach 2:
The patent extracts the measurement function from the complex electrical domain and places it in the optical domain. By detecting light emitted during carrier recombination, the measurement capability is separated from the complex electronics required by traditional electrical measurement methods, simplifying the overall system.
3Productivity
If MOSFET is operated with high frequency gate signal, then application performance is improved, but degradation mechanism is triggered that is difficult to measure
Solution Approach 1:
The patent replaces electrical measurement methods with optical detection to measure degradation under high-frequency operation. The photodetector continuously monitors light intensity from carrier recombination, providing a measurement method that works effectively under high-frequency gate signals where traditional electrical measurement becomes difficult.
Solution Approach 2:
The patent enables continuous monitoring of degradation during high-frequency operation. The optical detection system operates continuously without interruption, measuring threshold voltage drift in real-time even when the MOSFET is subjected to high-frequency gate signals, ensuring uninterrupted monitoring capability.
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 accurate, non-invasive monitoring of MOSFET degradation during operation, providing early warnings for device failure and enabling predictive maintenance without disrupting circuit operation.
Implementation Method 1
an optical device degradation sensor, such as a photodetector, is integrated with the MOSFET to measure photonic emissions from carrier recombination
Data Source
Figure 1~2C
Figure 2A~2B
Figure 3
AI summary
A semiconductor device includes: a semiconductor body (100); an electrical device (102) formed in an active region (104) of the semiconductor body (100), the active region (104) including an interface between the semiconductor body (100) and an insulating material; and a sensor (106) having a bandwidth tuned to at least part of an energy spectrum of light (604) emitted by carrier recombination at the interface when the electrical device (102) is driven between accumulation and inversion, wherein an intensity of the emitted light (604) is proportional to a density of charge trapping states (108) at the interface, wherein the sensor (106) is configured to output a signal that is proportional to the intensity of the sensed light. Corresponding methods of monitoring and characterizing the semiconductor device and a test apparatus are also described.