Integrated Thin-Film Resistor Thermal Calibration
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Solution Overview
Problem
Current integrated circuits with integrated thin-film resistive sensors require extensive factory-level testing in a thermally-controlled environment for accurate temperature calibration and compensation, which is costly and time-consuming, especially in high-volume production.
Innovation Solution
The integrated circuit design includes a substrate with a first and second metal layer surrounding the resistive layer, thermally conductive vias for temperature equalization, and a controllable heat source and reference temperature sensor for on-line, wafer-level, or die-level thermal calibration, allowing for accurate resistance measurement and compensation without extensive factory-level testing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If extensive factory-level testing in a thermally-controlled environment is performed for accurate temperature calibration and compensation, then measurement precision is improved, but productivity deteriorates and manufacturing cost increases
Solution Approach 1:
The patent implements preliminary thermal calibration by integrating a heater and temperature sensor directly with the sense resistor on the same die. This allows calibration measurements to be performed early in the manufacturing process (wafer-level or die-level) before final assembly, eliminating the need for costly post-assembly thermal testing. The heater pre-heats the resistor to various temperatures while the sensor records resistance values, enabling creation of a calibration lookup table that compensates for temperature variations in final application.
Solution Approach 2:
The patent merges the sense resistor, heater, and temperature sensor into a single integrated structure on the same die. The heater is positioned adjacent to the sense resistor with thermal coupling, and the temperature sensor is integrated to measure the resistor's temperature directly. This integration ensures that all three elements experience identical thermal conditions, eliminating thermal gradient errors and enabling accurate in-situ calibration without requiring separate thermal testing equipment.
2Measurement precision
If extensive factory-level testing in a thermally-controlled environment is performed for accurate temperature calibration and compensation, then measurement precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent implements preliminary thermal calibration by integrating a heater and temperature sensor directly with the sense resistor on the same die. This allows calibration measurements to be performed early in the manufacturing process (wafer-level or die-level) before final assembly, eliminating the need for costly post-assembly thermal testing. The heater pre-heats the resistor to various temperatures while the sensor records resistance values, enabling creation of a calibration lookup table that compensates for temperature variations in final application.
Solution Approach 2:
The integrated heater and temperature sensor enable the sense resistor to perform its own thermal calibration without requiring external testing equipment or thermally-controlled environments. The heater generates the necessary temperature range, the sensor measures the actual temperature, and the system automatically creates a calibration lookup table stored in memory, making the entire calibration process self-contained and eliminating costly external testing facilities.
3Measurement precision
If extensive factory-level testing in a thermally-controlled environment is performed for accurate temperature calibration and compensation, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The patent implements preliminary thermal calibration by integrating a heater and temperature sensor directly with the sense resistor on the same die. This allows calibration measurements to be performed early in the manufacturing process (wafer-level or die-level) before final assembly, eliminating the need for costly post-assembly thermal testing. The heater pre-heats the resistor to various temperatures while the sensor records resistance values, enabling creation of a calibration lookup table that compensates for temperature variations in final application.
Solution Approach 2:
The calibration process uses continuous heating cycles where the heater progressively raises the temperature through multiple steps (e.g., 25°C, 50°C, 75°C, 100°C, 125°C), with the temperature sensor continuously monitoring and the system automatically recording resistance values at each step. This continuous automated process eliminates idle time between measurements and enables complete calibration in a single uninterrupted sequence, significantly reducing total calibration time compared to manual methods.
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 enables accurate thermal calibration and compensation of resistive sensors within integrated circuits, reducing production costs and time by allowing for on-line or package-level calibration, ensuring precise resistance measurements across varying temperatures.
Implementation Method 1
a plurality of thermally conductive vias bonded to the first metal layer and the second metal layer to provide thermal flow to at least partially equalize a temperature of the first metal layer and the second metal layer
Implementation Method 2
the first metal layer and the second metal layer at least partially equalize a temperature along a length and a width of the resistive layer
Data Source
AI summary
An integrated circuit (IC) provides on-line, wafer-level, die-level, or package-level thermal calibration of an integrated thin-film resistor, by thermally enclosing the thin-film resistor with metal layers formed above and below the thin-film resistor along its length and width. Metal vias thermally couple the metal layers to the substrate to at least partially equalize the temperature of the metal layers and the thin-film resistor and the substrate. A controllable heat source, which may be provided by another thin-film resistor integrated on or below the substrate, and a reference temperature sensor provide heating/calibration measurement of the resistance of the thin-film resistor over a range of temperature. The reference temperature sensor may be provided within the IC, for example, integrated on the substrate or packaged with the die containing the thin-film resistor, or may be otherwise thermally coupled to the metal layers, e.g., by an extension of one of the metal layers.