Integrated Thermistor-Bias Resistor Die for Compact Temperature Sensing
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Solution Overview
Problem
The integration of thermistors and bias resistors in semiconductor devices has been elusive due to disparate materials and conflicting thermal budget limits, requiring separate components on a circuit board and occupying additional space.
Innovation Solution
An integrated semiconductor die is developed, featuring a thermistor with high temperature coefficient of resistance (TCR) and a bias reference resistor with low or zero TCR, both formed on the same substrate, allowing for independent tuning and integration in a voltage divider configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If thermistors and bias resistors are fabricated as separate discrete components, then each component can be independently optimized for its specific function, but additional space is required for purchase and mounting of two separate products
Solution Approach 1:
The patent combines the thermistor and bias resistor into a single integrated semiconductor die, where the thermistor is formed in an n-well region and the bias resistor is formed in a p-type substrate region. This merging eliminates the need for two separate discrete components, reducing circuit board space while maintaining independent optimization of each component's electrical characteristics through separate doping and fabrication processes.
Solution Approach 2:
The patent transitions from a planar arrangement of discrete components on a circuit board to a vertical integration architecture within the semiconductor die. The thermistor and bias resistor are stacked in different vertical layers (n-well region versus p-type substrate region), allowing three-dimensional utilization of space and enabling both components to coexist on a single die without occupying additional circuit board area.
2Area of stationary object
If thermistors and bias resistors are integrated on the same substrate, then space and cost are minimized, but disparate materials and conflicting thermal budget limits make integration elusive
Solution Approach 1:
The patent applies local quality by creating spatially distinct regions on the semiconductor substrate with different material properties and doping characteristics. The thermistor region (n-well) and bias resistor region (p-type substrate) are locally optimized for their respective functions, allowing each component to be fabricated with appropriate materials and thermal budgets while maintaining overall process compatibility through selective processing steps.
Solution Approach 2:
The patent segments the semiconductor substrate into distinct functional regions: an n-well region for the thermistor and a p-type substrate region for the bias resistor. This segmentation allows independent optimization of fabrication parameters for each component type, enabling integration despite conflicting thermal budget requirements by processing each region with its own optimized parameters.
3Measurement precision
If a voltage divider circuit uses a thermistor with high TCR and a bias reference resistor with low or zero TCR, then precise temperature sensing is achieved, but the circuit requires two separate components increasing device complexity
Solution Approach 1:
The patent merges the thermistor and bias reference resistor into a single integrated voltage divider circuit on one semiconductor die. The thermistor in the n-well region provides high TCR for temperature sensing, while the bias resistor in the p-type substrate region provides low or zero TCR for reference stability. This integration maintains the precise temperature sensing functionality while reducing device complexity by eliminating the need for two separate discrete components and their associated mounting and interconnection requirements.
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 solution minimizes space and cost by integrating both components on a single die, enabling miniaturization and precise resistance tuning, overcoming the limitations of separate component fabrication and thermal budget conflicts.
Implementation Method 1
Thermistors are temperature sensing components that have resistance configured to change with temperature, e.g., having a high temperature coefficient of resistance (TCR) over a suitable range
Implementation Method 2
a bias reference resistor that does not change the resistance (or changes very little) with respect to temperature in an operational range, thereby exhibiting a low or zero TCR
Data Source
AI summary
An electronic device including a thermistor and a bias reference resistor in a voltage divider configuration integrated into a single die and a method of fabricating the same. In an example, the electronic device comprises a substrate including an n-well region, a thermistor formed in the n-well region, and a bias resistor connected in series to the thermistor, the bias resistor formed in a region of the substrate isolated from the n-well region.