Vertical Microbolometer Leg Structure for Higher Fill Factor
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Solution Overview
Problem
The challenge in designing efficient microbolometer systems is to increase the light-sensitive area while minimizing the area occupied by leg supports, which limits the fill factor of the focal plane array without compromising device performance.
Innovation Solution
The implementation of vertically oriented microbolometer legs, formed using spacer deposition and etch processing, reduces the surface area occupied by the legs while maintaining their structural integrity and performance, allowing for a higher fill factor without reducing the leg's area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If conventional horizontal legs are used to connect microbolometer bridges to contacts, then structural integrity is maintained, but the area occupied by leg supports increases, reducing the fill factor of the array
Solution Approach 1:
The patent transitions from conventional horizontal in-plane legs to vertical out-of-plane legs that extend perpendicular to the substrate surface. This dimensional change allows the legs to connect the bridge to contacts below without occupying significant lateral area, thereby increasing the fill factor while maintaining structural integrity and electrical connection functionality.
2Area of moving object
If the width and length of leg supports are reduced to increase fill factor, then more area is available for light-sensitive elements, but device performance may be compromised
Solution Approach 1:
By moving the legs to the vertical dimension, the patent decouples the area requirements for structural connection from the lateral area available for light-sensitive elements. The vertical legs maintain sufficient cross-sectional area for mechanical and electrical performance while occupying minimal footprint area, allowing the light-sensitive area to be maximized without compromising device performance.
Solution Approach 2:
The patent changes the geometric parameters of the leg structure by orienting it vertically rather than horizontally. This parameter change allows the legs to achieve the necessary structural and electrical performance with a smaller lateral footprint, enabling increased fill factor while maintaining device performance through optimized vertical dimensioning.
3Area of moving object
If vertically oriented legs are implemented to reduce surface area, then fill factor increases, but manufacturing complexity may increase
Solution Approach 1:
The vertical orientation of legs leverages standard semiconductor vertical processing techniques such as spacer deposition and etch release, which are well-established in the industry. While the geometry is more complex than horizontal legs, the manufacturing approaches remain within conventional semiconductor process capabilities, making the transition feasible without requiring entirely new manufacturing methodologies.
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 enhances the fill factor of the microbolometer array by minimizing the area occupied by leg supports while maintaining the necessary structural and performance characteristics, thereby improving the efficiency of infrared detectors.
Implementation Method 1
The leg structure includes a metal layer having a first dimension that extends in a first direction that is substantially perpendicular to the plane and a second dimension that extends in a second direction that is substantially parallel to the plane, where the first dimension is greater than the second dimension
Implementation Method 2
A microbolometer is an example of a type of infrared detector that may be used within an infrared imaging device
Implementation Method 3
The change in resistance of each microbolometer is translated into a time-multiplexed electrical signal
Implementation Method 4
Each microbolometer includes a light-sensitive portion formed from resistive material suspended on a bridge
Data Source
AI summary
Microbolometer systems and methods are provided herein. For example, an infrared imaging device includes a substrate having contacts and a surface. The surface defines a plane. The infrared imaging device further includes a microbolometer array coupled to the substrate. Each microbolometer of the microbolometer array includes a second having a first dimension that extends in a first direction substantially parallel to the plane and a second dimension that extends in a second direction away from the plane. The first dimension is less than the second dimension. The segment includes a metal layer and a layer formed on a side of the metal layer.