Vertically Constructed Thermistor for High Resistance
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Solution Overview
Problem
Conventional thermistor structures with large temperature-sensitive silicon areas limit resistance values to 1-2 kΩ due to current spreading, making it difficult to achieve high resistance and tight tolerance in temperature-sensing applications.
Innovation Solution
A vertically constructed thermistor design with a reduced cross-sectional area and an isolation trench, coupled with a modular thermistor array and bondpad connections, allows for the generation of high resistance thermistor units that can be trimmed to achieve precise resistance values up to 100 kΩ.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional thermistor structures with large temperature-sensitive silicon areas are used, then current spreading is reduced, but resistance values are limited to 1-2 kΩ
Solution Approach 1:
The patent transitions from a planar thermistor structure to a vertically constructed structure. The temperature-sensitive region is formed as a vertical column between upper and lower contacts, utilizing the vertical dimension rather than expanding the horizontal silicon area. This dimensional change allows current to flow vertically through a confined cross-sectional area, achieving high resistance without requiring large silicon areas.
Solution Approach 2:
The patent divides the temperature-sensitive region into multiple segments or regions with different doping concentrations along the vertical axis. This segmentation allows different portions of the vertical column to contribute differently to the overall resistance, enabling precise control of the total resistance value while maintaining a compact structure.
2Use of energy by moving object
If high resistance thermistors are designed to reduce power consumption, then bias current and power consumption are reduced, but achieving high resistance with tight tolerance becomes difficult
Solution Approach 1:
The patent employs parameter changes by varying the doping concentration, cross-sectional area, and length of the vertical temperature-sensitive region to achieve different resistance values. By controlling these parameters during fabrication, the patent can achieve high resistance values with tight tolerances. The vertical structure allows independent control of cross-sectional area and length, providing additional degrees of freedom for resistance optimization.
Solution Approach 2:
The patent incorporates trimming mechanisms that allow post-fabrication adjustment of the resistance value. This feedback approach enables fine-tuning of the resistance to achieve tight tolerances after the initial fabrication, ensuring that high resistance values meet specified tolerance requirements.
3Manufacturing precision
If vertically constructed thermistor design with reduced cross-sectional area is used, then resistance can be increased beyond conventional limits, but device complexity increases
Solution Approach 1:
The vertical construction methodology can be applied to various thermistor designs and integrated into different circuit configurations. The same basic vertical structure principle can achieve different resistance values by modifying doping profiles or dimensions, providing a universal approach that reduces overall device complexity through standardization.
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 design effectively increases thermistor resistance beyond conventional limits, enabling high resistance and tight tolerance requirements while allowing for adjustment through trimming, thereby reducing power consumption in temperature-sensing applications.
Implementation Method 1
a third doped region between the first and second doped regions, the third doped region including a temperature sensitive semiconductor material
Data Source
AI summary
Methods and apparatus providing a vertically constructed, temperature sensing resistor are disclosed. An example apparatus includes a semiconductor substrate including a plurality of resistor unit cells arranged in an array, each resistor unit cell formed within the semiconductor substrate and including a top contact. A conductive layer located over the semiconductor substrate electrically connects to a subset of the top contacts.