Bolometer Absorber Suspension via Vertical Segmentation
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Solution Overview
Problem
Previous bolometer infrared sensors face issues with stress-induced buckling and shifting of the absorber element due to integrated support structures, leading to reduced planarity and non-uniform spacing, which affects accuracy and consistency, and the L-shaped arms reduce the fill factor.
Innovation Solution
A bolometer infrared sensor design featuring a fixed beam suspension structure predominantly at one level and an absorber structure at a second level, using multiple sacrificial layers and atomic layer deposition for precise control, with a pillar structure to thermally isolate and decouple the absorber from stress, allowing for separate materials and larger supports without reducing fill factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the absorber element and support structure are integrated and suspended at the same level, then the structure is simplified and easier to manufacture, but stress-induced buckling and shifting occur reducing planarity and accuracy
Solution Approach 1:
The patent divides the previously integrated absorber-support structure into two separate structures: an absorber structure suspended at a first level and a support structure suspended at a second level. This segmentation allows each structure to be independently designed and optimized, preventing stress transfer that causes buckling while maintaining manufacturing simplicity through separate deposition processes.
Solution Approach 2:
The patent introduces a vertical dimension separation by suspending the absorber and support structures at different heights above the substrate. This three-dimensional arrangement decouples the stress fields of the two structures, eliminating the buckling problem while preserving the integrated design benefits through vertical stacking rather than horizontal integration.
2Reliability
If L-shaped arms are used to suspend the absorber and support structure, then the structures are effectively suspended above the substrate, but the fill factor is reduced
Solution Approach 1:
By separating the absorber and support structures into different vertical levels, the patent eliminates the need for L-shaped connecting arms. Each structure can be suspended directly from the substrate via independent support beams, creating a more compact footprint that maximizes the fill factor while maintaining reliable suspension.
Solution Approach 2:
The patent transitions from a two-dimensional planar suspension arrangement with L-shaped arms to a three-dimensional vertical stacking arrangement. This dimensional change allows both structures to be suspended effectively without requiring horizontal extension arms, thereby increasing the active area and fill factor.
3Device complexity
If the absorber and support structure are at the same level, then the device structure is compact, but non-uniform spacing between absorber and substrate occurs affecting accuracy
Solution Approach 1:
The patent segments the device into vertically stacked functional layers with the absorber at a first level and support structure at a second level. This segmentation enables uniform spacing control for each layer independently, ensuring consistent detection accuracy while maintaining overall device compactness through vertical integration.
Solution Approach 2:
By arranging the absorber and support structure at different vertical levels, the patent creates uniform horizontal spacing between each structure and the substrate. This vertical separation eliminates the non-uniform spacing problem that occurs in co-planar designs, improving measurement precision while keeping the device footprint compact.
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 design enhances the planarity and accuracy of the sensor, reduces stress-induced issues, and maintains a high fill factor by thermally isolating the absorber and decoupling it from stress, improving the overall performance and reliability of the infrared radiation detection.
Implementation Method 1
an absorber element for absorbing infrared radiation
Implementation Method 2
heat generated by the absorbed radiation is transferred to the transducer element
Implementation Method 3
a transducer element in thermal contact with the absorber element that has an electrical resistance that varies with temperature
Implementation Method 4
using multiple sacrificial layers and atomic layer deposition for precise control
Data Source
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Figure 2
AI summary
A semiconductor device includes a substrate having an upper surface that defines a sensing region. A fixed beam structure is supported at a first level above the sensing region. The fixed beam structure includes fixed beam supports that extend upwardly from the upper surface of the substrate to position the fixed beam structure at the first level above the sensing region. An absorber structure is supported above the fixed beam structure at a second level above the sensing region. The absorber structure includes a pillar support that extends upwardly from the fixed beam structure to position the absorber structure at the second level above the sensing region.