MOSFET IDR Thermal Sensing Without N-Well Diffusion
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Solution Overview
Problem
Newer semiconductor processes lack N-well diffusion layers, making it difficult to form P/N junctions for thermal sensing, and sub-threshold MOSFET performance is inconsistent, while resistance temperature detectors (RTDs) have limitations in sensing hot spots due to metal layer placement.
Innovation Solution
Inversion diffusivity resistance (IDR) thermal sensors using series-connected MOSFETs provide a temperature-dependent resistance for accurate thermal sensing without N-well diffusion layers, offering an alternative to P/N junctions and RTDs, with improved accuracy and integration with existing MOSFET layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If P/N junction thermal sensing is used, then temperature measurement capability is achieved, but N-well diffusion layers are required which are absent in newer processes
Solution Approach 1:
The patent changes the sensing mechanism from P/N junction voltage measurement to MOSFET inversion layer resistance measurement. By applying gate voltage to MOSFETs and measuring the resistance of the inversion layer in the drain-source path, temperature can be sensed without requiring N-well diffusion layers, thus adapting to newer manufacturing processes while maintaining temperature measurement capability
Solution Approach 2:
The patent substitutes the physical structure requirement (P/N junction) with an electrical field-based measurement (inversion layer resistance in MOSFET). This replacement eliminates the need for specific diffusion layer structures while achieving the same thermal sensing function through field-effect transistor physics
2Measurement precision
If sub-threshold MOSFET operation is used for thermal sensing, then temperature measurement is possible, but performance consistency is poor
Solution Approach 1:
The patent uses MOSFETs operating in the strong inversion region rather than sub-threshold operation. By applying sufficient gate voltage to ensure strong inversion, the measurement operates in a more robust and consistent regime, improving performance reliability while maintaining temperature sensing capability
Solution Approach 2:
The patent utilizes the inherent temperature-dependent properties of the MOSFET inversion layer itself as the sensing element. The inversion layer resistance naturally varies with temperature, and this intrinsic property is directly measured, eliminating the need for external sensing structures and improving consistency
3Measurement precision
If RTD thermal sensing is used, then temperature measurement is achieved, but metal routing must be placed far from the hot spot being monitored
Solution Approach 1:
The patent makes the MOSFET serve dual functions: as a computing element in the processor and as a thermal sensor. The same MOSFET structure used for logic operations also provides temperature sensing through its inversion layer resistance, eliminating the need for separate RTD structures and distant metal routing
Solution Approach 2:
The patent merges the thermal sensing function with the existing MOSFET logic structure. By using the drain-source resistance of standard MOSFETs as the sensing element, the sensor and the computing element are combined into a single structure, allowing temperature measurement at the exact location of hot spots without additional routing
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 IDR thermal sensors enhance temperature monitoring accuracy near hot spots, are independent of MOSFET process changes, and can be easily integrated with core device areas, reducing routing efforts and maintaining consistent performance.
Implementation Method 1
provides a temperature dependent resistance through the drain/source paths
Implementation Method 2
inversion diffusivity resistance (IDR) thermal sensors
Data Source
AI summary
A device including a first plurality of metal-oxide semiconductor field-effect transistors electrically connected in series. Each of the first plurality of metal-oxide semiconductor field-effect transistors includes a first gate structure, a first drain/source region on one side of the first gate structure, and a second drain/source region on another side of the first gate structure. The first gate structure of each of the first plurality of metal-oxide semiconductor field-effect transistors is configured to receive a bias voltage to bias on the first plurality of metal-oxide semiconductor field-effect transistors and provide a temperature dependent resistance through the first plurality of metal-oxide semiconductor field-effect transistors to measure temperatures.