Integrated Multi-Band Focal Plane Array Thermal Mismatch
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Solution Overview
Problem
Conventional infrared detector arrays require separate focal plane arrays for visible and infrared spectra, leading to increased complexity and cost due to thermal mismatch issues with non-silicon-based window materials, which complicates packaging and reduces efficiency.
Innovation Solution
An integrated multi-band focal plane array is developed, allowing simultaneous imaging in both visible and infrared spectra using a single array, with visible radiation reaching CMOS imaging circuitry through openings in the microbolometer membrane, enabling high-performance infrared detection with reduced thermal response time and frame rate capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate focal plane arrays are used for visible and infrared spectra, then detection capability for each spectrum is improved, but device complexity and packaging difficulty increase due to thermal mismatch issues with non-silicon-based window materials
Solution Approach 1:
The patent combines visible and infrared detection capabilities into a single integrated focal plane array. The microbolometer membrane structure serves dual purposes: it enables infrared detection while containing openings that allow visible light to reach underlying CMOS imaging circuitry. This merging eliminates the need for separate focal plane arrays and complex multi-material packaging, reducing thermal mismatch issues while maintaining detection capabilities for both spectra.
Solution Approach 2:
The microbolometer membrane structure is designed to perform multiple functions simultaneously: it acts as the infrared-sensitive detection element, provides thermal isolation, and serves as an optical window with integrated openings for visible light transmission. This multi-functionality reduces the number of separate components needed and simplifies the overall device architecture, addressing the packaging complexity issue while maintaining reliable detection for both visible and infrared spectra.
2Reliability
If thermal isolation of microbolometer is increased to improve sensitivity, then sensitivity is improved, but response time becomes slower
Solution Approach 1:
The patent applies local quality by creating a non-uniform thermal isolation structure. The microbolometer membrane has regions of high thermal isolation (the membrane itself and its support legs) to maintain sensitivity, while also incorporating localized thermal conduction paths through the openings in the membrane. These openings allow controlled heat dissipation to underlying structures, enabling the device to achieve both high sensitivity and fast response time by optimizing thermal properties in different local regions.
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 enables cost-effective, high-performance multi-spectral imaging by integrating visible and infrared detection within a single focal plane array, reducing thermal response time and allowing for higher frame rates while addressing thermal mismatch issues.
Implementation Method 1
Infrared (IR) detectors are often utilized to detect fires, overheating machinery, planes, vehicles, people, and any other objects that emit thermal radiation
Implementation Method 2
Microbolometers are infrared radiation detector elements that are fabricated on a substrate material using traditional integrated circuit fabrication techniques
Implementation Method 3
visible radiation reaching CMOS imaging circuitry through openings in the microbolometer membrane
Data Source
AI summary
Systems and methods for bonding semiconductor devices and/or multiple wafers, in the form of a first segmented wafer and a second unsegmented wafer which may have different temperature coefficients of expansion (TCE), and which may be bonded together, with or without the presence of a vacuum.