IR Thermopile Sensor Front-End Implant for Temperature Resolution
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Solution Overview
Problem
Standard thermopile sensor fabrication processes, particularly those using back-end layers, suffer from low temperature resolution due to low temperature coefficients and increased complexity and cost, especially with non-conventional materials like nickel.
Innovation Solution
The implementation of a front-end process for fabricating an infrared thermopile sensor using a silicon substrate with high temperature coefficient implant regions, forming thermocouples in series, and connecting them with metallic interconnects to bond pads, reduces complexity and cost while enhancing temperature resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If back-end layers are used for thermopile sensor fabrication, then the manufacturing process is simpler, but the temperature resolution is low due to low temperature coefficients
Solution Approach 1:
The patent inverts the conventional fabrication sequence by performing the implantation process during front-end processing rather than back-end processing. This allows the use of high temperature coefficient materials in the front-end layers, achieving improved temperature resolution while maintaining compatibility with standard CMOS fabrication workflows.
Solution Approach 2:
The patent changes the temperature coefficient parameter by selecting specific dopant types and concentrations during front-end implantation. By adjusting these parameters, the invention achieves high temperature coefficients in the front-end layers, directly improving temperature resolution without requiring complex back-end material processing.
2Measurement precision
If non-conventional materials like nickel are used in thermopile fabrication, then temperature resolution may improve, but manufacturing complexity and cost increase
Solution Approach 1:
The patent achieves high temperature resolution by changing the dopant concentration and type parameters during standard front-end implantation, eliminating the need for non-conventional materials like nickel. This approach maintains compatibility with existing CMOS processes while achieving the desired temperature sensitivity.
3Measurement precision
If external reference temperature detectors are used, then temperature measurement accuracy improves, but device size and cost increase
Solution Approach 1:
The patent merges the temperature reference function directly into the front-end implantation regions of the thermopile sensor. By integrating this reference functionality into the existing sensor structure during front-end processing, the invention eliminates the need for separate external reference temperature detectors, thereby reducing device size and complexity while maintaining measurement accuracy.
Solution Approach 2:
The front-end implantation regions serve multiple functions: they act as both the temperature reference and part of the thermopile sensing structure. This multi-functionality eliminates the need for dedicated external reference components, reducing overall device complexity and size.
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 results in improved temperature resolution, reduced product size, and eliminates the need for external reference temperature detectors, simplifying the process and lowering costs.
Implementation Method 1
a silicon substrate that has been implanted during front-end processing to form an implant region
Implementation Method 2
A thermopile can include an electronic device that converts thermal energy into electrical energy. It is composed of several thermocouples often connected in series or in parallel. Thermopiles do not respond to absolute temperature, but generate an output voltage proportional to a local temperature difference or a temperature gradient.
Data Source
AI summary
An infrared thermopile sensor, an electronic device, and a method for fabricating an infrared thermopile sensor using a front-end process that employ example techniques in accordance with the present disclosure are described herein. In an implementation, the infrared thermopile sensor includes a silicon substrate that has been implanted during front-end processing to form an implant region; a passivation layer disposed on a first side of the silicon substrate, where the passivation layer forms a membrane; and an interlayer dielectric formed on the passivation layer, where the interlayer dielectric includes at least one thermopile that includes at least one thermocouple in series; and at least one metallic interconnect that electrically couples the at least one thermopile to a bond pad; and at least one bond pad interconnect that electrically couples the implant region to the bond pad.