Self-Heating Free I-V Extraction via Thermal Modeling
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Solution Overview
Problem
Conventional methods for obtaining self-heating free I-V characteristics of transistors, such as SOI transistors, are inefficient and inaccurate, leading to inaccuracies in transistor modeling due to self-heating effects during DC operation.
Innovation Solution
A method involving the measurement of drain and substrate currents at varying ambient temperatures to determine self-heating free I-V characteristics by using equations to calculate temperature increases and channel temperatures, allowing for the extraction of accurate self-heating free current models.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If DC operation measurement is used to obtain I-V characteristics, then measurement simplicity is improved, but self-heating effects cause inaccuracy in the characteristics
Solution Approach 1:
The patent introduces an intermediary mathematical model that separates the self-heating effects from the measured I-V characteristics. By using the measured drain current and power dissipation data along with thermal resistance parameters, the model calculates and removes the self-heating component, yielding accurate self-heating free characteristics without requiring complex measurement setups
Solution Approach 2:
The patent changes the parameter space by introducing temperature as a variable parameter. By measuring I-V characteristics at multiple ambient temperatures and using thermal resistance to calculate temperature rises, the method transforms the problem from directly measuring self-heating free characteristics to extracting them through parameter-based mathematical relationships
2Measurement precision
If nanosecond short pulse measurement is used to obtain self-heating free I-V characteristics, then measurement accuracy is improved, but device complexity and measurement setup requirements increase
Solution Approach 1:
The patent replaces the mechanical/pulsed measurement approach with a mathematical modeling approach. Instead of using nanosecond pulses and complex timing circuits to avoid self-heating, the method uses steady-state DC measurements combined with thermal resistance-based mathematical models to extract self-heating free characteristics, substituting physical measurement complexity with computational analysis
3Ease of operation
If AC conductance integration is used to extract self-heating free I-V curves, then measurement procedure is simplified, but modeling accuracy deteriorates
Solution Approach 1:
The patent employs feedback by using the measured power dissipation and thermal resistance to calculate temperature rise, which then feeds back into the I-V characteristic extraction process. The method iteratively adjusts for self-heating effects based on the calculated temperature dependencies, improving accuracy while maintaining procedural simplicity compared to AC conductance integration
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 provides accurate self-heating free I-V characteristics, enabling more precise transistor modeling and improving circuit design and fabrication by accounting for current-temperature relationships.
Implementation Method 1
Self-heating refers to an increase in the temperature of a transistor, such as an SOI transistor, over ambient temperature that can occur under DC operation as a result of large power generation and poor thermal conductivity of the transistor
Data Source
AI summary
According to one exemplary embodiment, a method for determining a self-heating free drain current in a transistor corresponding to a channel temperature not affected by a drain DC current includes measuring at least three unique drain currents of a transistor corresponding to at least three unique ambient temperatures. The method further includes determining at least three unique channel temperatures of the transistor corresponding to the at least three unique drain currents, thereby establishing a current-temperature relationship for the transistor. The method further includes determining the self-heating free drain current of the transistor utilizing the current-temperature relationship.