Post-Supported Microbolometer Pixel Design
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Solution Overview
Problem
The performance of microbolometer pixels is degraded due to the large area required for the cone-shaped pixel contact structure, which both supports the pixel and provides electrical interconnect, leading to wasted space and poor scalability as pixel sizes are reduced.
Innovation Solution
Replacing the large, sloped cone-shaped structure with small, vertically-sided metal posts that provide both mechanical support and electrical interconnect, fabricated using standard silicon chip processing techniques, allowing for reduced area usage and enhanced active sensing capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large, sloped, cone-shaped structure is used to support the pixel and provide electrical interconnect, then mechanical support and electrical connection are achieved, but the pixel area is significantly reduced and scalability is poor
Solution Approach 1:
The invention divides the support function into multiple discrete posts rather than using a single large cone-shaped structure. Each post is a separate element that provides localized support and electrical connection, allowing the pixel area to be maximized while maintaining necessary mechanical and electrical functions.
Solution Approach 2:
The invention transitions from a two-dimensional planar contact structure to a three-dimensional vertical post structure. By extending the support and interconnect function into the vertical dimension with posts having height, the pixel can maintain full planar area while achieving the necessary mechanical support and electrical connection through vertical pathways.
2Measurement precision
If pixel size is reduced to improve resolution, then image quality improves, but the contact structure represents a larger fraction of pixel area
Solution Approach 1:
By segmenting the contact structure into multiple small posts rather than one large structure, the invention enables pixel size reduction while keeping the total contact area fraction low. Each post occupies minimal space, allowing more of the pixel area to be dedicated to sensing elements even at smaller pixel dimensions.
Solution Approach 2:
The vertical orientation of posts allows the contact structure to occupy minimal planar area while providing sufficient support and electrical connection. This dimensional transition enables continued pixel size reduction for higher resolution without the contact structure becoming a dominant fraction of the pixel area.
3Area of stationary object
If a compact post structure is used to reduce area, then active sensing area increases, but manufacturing complexity may increase
Solution Approach 1:
The invention incorporates support posts and electrical interconnects during the pixel fabrication process itself, rather than adding them as separate subsequent steps. The posts are formed as part of the pixel structure fabrication sequence, integrating multiple functions into a unified manufacturing flow that reduces overall process complexity.
Solution Approach 2:
The invention combines the mechanical support function and electrical interconnect function into a single integrated post structure. This merging of functions eliminates the need for separate support elements and separate electrical contact elements, simplifying the manufacturing process while maximizing the active sensing area.
Data Source
AI summary
A post-supported bolometer pixel and a process for manufacturing it comprising the steps of depositing a sacrificial layer over a substrate with readout integrated circuit pads that connect to the integrated circuit; forming vias through the sacrificial layer to the metal pads connecting to the readout integrated circuit; filling the vias with metal and polishing said metal to the surface of the sacrificial layer; forming microbolometer pixel layers over the filled vias and sacrificial layer; and removing the sacrificial layer to leave a post-supported pixel.