GaN Device Intermittent Life Measurement via Junction Temperature Control
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Solution Overview
Problem
Current methods for measuring the intermittent operating life (IOL) of GaN-based devices are inefficient and costly, particularly for batch processing, due to high costs associated with infrared temperature sensing equipment and slow response times of thermal couples, and require high-precision operational amplifiers and multiple digital signal processors for accurate junction temperature measurement.
Innovation Solution
A system and method that includes a controlling unit to detect signals from the drain and source terminals of a GaN-based device, a stressing unit to increase junction temperature, a cooling unit to decrease it, and a measure-bias unit to supply a regulated drain-source current, allowing for precise measurement of drain-source resistance at different temperature states, thereby eliminating the influence of parasitic parameters and package structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If infrared temperature sensing equipment is used to measure device temperature, then measurement precision is improved, but device complexity and cost increase significantly
Solution Approach 1:
The patent introduces an intermediary substance (thermally conductive paste) and intermediary structure (reference block with known thermal resistance) to transfer and standardize thermal conditions from the heating element to the device under test. This intermediary approach enables accurate temperature measurement through electrical parameters without requiring complex infrared equipment
Solution Approach 2:
The patent replaces the mechanical/optical infrared temperature sensing system with an electrical measurement system. By measuring electrical parameters (voltage, current, resistance) and using thermal-electrical analogies, the system achieves temperature measurement without mechanical contact or complex optical equipment
2Device complexity
If thermal-couple is used to measure device temperature, then device complexity is reduced, but productivity decreases due to slow response speed
Solution Approach 1:
The patent replaces the slow thermal-couple mechanical contact method with an electrical measurement system that uses voltage and current measurements to determine resistance, which directly correlates to temperature. This electrical approach provides rapid response without the thermal inertia limitations of physical thermal couples
Solution Approach 2:
The patent changes the measurement parameter from direct thermal contact (temperature) to electrical parameters (resistance, voltage, current) that correlate with temperature. By measuring resistance changes of the device under test at different temperatures, the system achieves fast temperature assessment without slow thermal coupling
3Measurement precision
If high-precision operational amplifiers and A/D circuits are used to measure drain-source voltage for junction temperature, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent introduces a reference block with known thermal resistance as an intermediary that standardizes the thermal path. This reference block enables temperature determination through simple resistance measurements without requiring complex high-precision amplification and conversion circuits
Solution Approach 2:
The patent changes the measurement approach from directly measuring tiny voltage drops across the device (requiring high-precision amplifiers) to measuring resistance changes through voltage and current measurements. By utilizing the device's own electrical characteristics and thermal-electrical relationships, the system achieves accurate temperature measurement with simpler circuits
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 achieves higher measurement accuracy and reduces costs by directly controlling junction temperature, ensuring consistent thermal resistance across devices and eliminating measurement errors related to package temperature and testing circuit inconsistencies.
Implementation Method 1
a stressing unit configured for applying a regulated stressing power Pstr to the DUT to increase a junction temperature of the DUT to an ON-junction temperature TjON
Implementation Method 2
a cooling unit configured for cooling the DUT to decrease the junction temperature of the DUT to an OFF junction temperature TjOFF
Data Source
AI summary
The present invention provides a system and method for measuring an intermittent operating life (IOL) of a GaN-based device under test (DUT) is provided. The system is operable in a stressing mode, a cooling mode and a measure mode. A power regulation approach is adopted to ensure that DUT of the same thermal resistance have same temperature increase during the IOL test. The present invention eliminates the influence caused by parasitic parameters of testing circuits and the inconsistency of threshold voltage and drain-source resistance of the device itself. Through power regulation, it is the junction temperature of the device, not the housing temperature of the device, being directly controlled. Therefore, higher measurement accuracy can be achieved.