Thermopile Sensor Non-Uniform Gap Metal Interconnect
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Solution Overview
Problem
Thermopile sensors face challenges in increasing sensitivity while maintaining reliability due to issues with forming thin metal films across gaps between thermocouples, leading to potential increases in resistance and breakage.
Innovation Solution
A thermopile sensor design where the metal interconnect crosses a wider gap between PolySi interconnects, with the gap width being 1.5 times or more and 5 times or less than the remaining gap width, and the metal interconnect is disposed on a stable frame to suppress heat escape and thermal stress, ensuring a thicker metal film formation and improved reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the gap between thermocouples is narrowed to increase sensitivity, then sensitivity is improved, but the metal film quality deteriorates and resistance increases
Solution Approach 1:
The gap width is made non-uniform: narrow in most regions for sensitivity, but wide at the metal interconnect crossing portion for reliable film formation. This local variation in gap width allows simultaneous optimization of both sensitivity and metal film reliability.
Solution Approach 2:
The metal interconnect is positioned to cross the gap at a predetermined location where the gap width is intentionally increased. This preliminary design ensures that the metal film can be formed with sufficient thickness and quality before final assembly, preventing later reliability issues.
2Measurement precision
If the metal film is made thin to improve sensitivity, then sensitivity is improved, but the metal film becomes prone to breakage and resistance increase
Solution Approach 1:
The metal interconnect is designed with varying width along its length: thin in regions where high sensitivity is needed, and wide at the gap crossing portion where mechanical strength and film quality are critical. This local variation resolves the contradiction between thinness for sensitivity and thickness for strength.
3Device complexity
If the metal interconnect is placed on the substrate without a frame, then device complexity is reduced, but thermal stability deteriorates
Solution Approach 1:
A frame structure is introduced as an intermediary element between the substrate and the metal interconnect. The frame provides a stable platform that isolates the metal interconnect from direct thermal effects on the substrate, improving thermal stability while maintaining overall device simplicity.
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 configuration enhances the sensitivity and reliability of thermopile sensors by preventing disconnection and resistance increases, allowing for effective temperature difference detection and improved flow rate measurement.
Implementation Method 1
a hot junction located on the same side as a heater and a cold junction located on the opposite side are connected to each other in a thermocouple constituting a thermopile, an electromotive force is generated in accordance with a temperature difference between the hot junction and the cold junction
Implementation Method 2
a width of a portion of the gap where the metal interconnect crosses the gap between the PolySi interconnects is greater than a width of a remaining portion of the gap between the PolySi interconnects
Data Source
AI summary
A thermopile sensor includes a thermopile. The thermopile is formed by connecting thermocouples, in series on an insulating film, in which a first PolySi interconnect and a metal interconnect including a metal portion in at least a part thereof are connected, each of the thermocouples connected in series is arranged side by side with a predetermined gap, the metal interconnect is arranged to overlap the first PolySi interconnect in each of the thermocouples, at a connection portion between a thermocouple and an adjacent thermocouple, the metal interconnect crosses the gap between the first PolySi interconnects, and a first width of a portion of the gap where the metal interconnect crosses the gap between the first PolySi interconnects is greater than a second width of a remaining portion of the gap between the first PolySi interconnects.