VOx Microbolometer Layout for Lower 1/f Noise
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Solution Overview
Problem
The performance of microbolometers used for detecting electromagnetic radiation is limited by noise associated with the thermistor material, particularly 1/f noise in the thermistor material based on vanadium oxide, which degrades their detection efficiency.
Innovation Solution
A process for fabricating microbolometers with a thermistor material based on vanadium oxide, where an additional chemical element is incorporated by ion implantation into the lateral segments, reducing their electrical resistivity and thereby minimizing excess 1/f noise, while maintaining optimal resistivity in the central segment for effective radiation detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ion implantation is carried out in the VOx to decrease electrical resistivity, then the electrical resistivity is reduced, but the device complexity increases
Solution Approach 1:
The patent applies local quality by performing ion implantation only in specific regions of the VOx layer - namely in the thermally insulating arms and at the borders of the absorbent membrane, while leaving the central region of the membrane unimplanted. This localized treatment reduces electrical resistivity where needed for electrical connection and noise reduction, while preserving the thermal and detection properties of the main sensing area.
Solution Approach 2:
The patent segments the VOx structure into different regions with different electrical properties: the central membrane region maintains higher resistivity for optimal detection, while the thermally insulating arms and border regions receive ion implantation to achieve lower resistivity for better electrical connection and reduced 1/f noise.
2Device complexity
If the VOx is deposited in the thermally insulating arms to avoid using metal, then the material complexity is reduced, but the electrical conductivity is insufficient
Solution Approach 1:
The patent changes the electrical parameter (resistivity) of the VOx material in the thermally insulating arms through ion implantation. By introducing dopant atoms into the VOx lattice in these specific regions, the electrical resistivity is significantly reduced, enabling the VOx to function as both a thermal insulator and an adequate electrical conductor in the biasing electrode function.
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
The process significantly decreases the electrical resistivity of the thermistor material's lateral segments, reducing excess noise and enhancing the overall performance of the microbolometer by making the noise impact negligible, thus improving detection efficiency.
Implementation Method 1
incorporating locally, by ion implantation, into the lateral segments of the thermistor material, an amount of said additional chemical element higher than or equal to the effective amount
Implementation Method 2
The thermistor material 14 is a material that has an electrical resistance that varies with its temperature
Implementation Method 3
the non-zero distance, which is preferably adjusted so as to form a quarter-wave interference cavity that optimizes the absorption by the absorbent membrane 10 of the electromagnetic radiation to be detected
Data Source
AI summary
A process for fabricating a microbolometer includes producing a membrane containing a thermistor material, which is made of a first compound based on vanadium oxide and which is formed from a central segment. The central segment covers an intermediate insulating layer, and the thermistor material is formed from lateral segments, which make contact with biasing electrodes through apertures. The process also includes incorporating locally, by ion implantation, into the lateral segments an amount of an additional chemical element higher than or equal to the effective amount. The electrical resistivity ρL at room temperature of the compound thus modified is lower than or equal to 10% of the electrical resistivity ρc at room temperature of the first compound.