Visible-Infrared Sensor Stack Layout With Reduced Thermal Budget
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Solution Overview
Problem
Existing imaging devices that acquire both visible and infrared images of the same scene face challenges in structural configuration and manufacturing methods, which affect their performance and integration.
Innovation Solution
The proposed imaging device includes a visible matrix sensor, an infrared matrix sensor, and a readout integrated circuit with a readout stack located between the sensitive layers of the visible and infrared sensors, and an interconnection stack on the rear face of the infrared sensor, connected by conductive vias.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the readout integrated circuit is assembled on the rear face of the infrared matrix sensor as in prior art, then the integration is achieved, but the thermal budget during manufacturing increases and sensitive layer quality deteriorates
Solution Approach 1:
The readout integrated circuit is segmented into two separate stacks: a readout stack positioned between the visible and infrared sensitive layers, and an interconnection stack positioned on the rear face of the infrared matrix sensor. This segmentation allows each stack to be optimized for its specific function and positioned to minimize thermal impact on the sensitive layers during manufacturing.
Solution Approach 2:
The readout circuit is distributed across multiple dimensional layers: the readout stack in the intermediate space between sensitive layers, and the interconnection stack on the rear face. This multi-dimensional arrangement reduces the thermal budget concentration that would occur with a single rear-face assembly, thereby preserving sensitive layer quality.
2Device complexity
If the readout stack is positioned on the rear face of the infrared sensor as in prior art, then the structure is simplified, but electrical connection efficiency decreases
Solution Approach 1:
The readout stack serves as an intermediary structure positioned between the visible and infrared sensitive layers. It provides direct electrical access to both sensor types through conductive vias, eliminating the need for long interconnection paths through the infrared sensor substrate and improving electrical connection efficiency while maintaining structural organization.
3Ease of manufacture
If a single interconnection stack is used as in prior art, then the manufacturing process is simpler, but thermal management during manufacturing becomes problematic
Solution Approach 1:
The interconnection functions are segmented into two separate stacks: the readout stack that handles signal readout between the sensitive layers, and the interconnection stack on the rear face that handles external connections. This segmentation distributes the thermal load during manufacturing across different locations and functions, preventing excessive thermal budget concentration.
4Volume of moving object
If the readout circuit is integrated monolithically on a single substrate as in prior art, then the overall dimensions are reduced, but the quality of sensitive layers deteriorates due to increased thermal budget
Solution Approach 1:
The readout circuit is distributed across multiple dimensional layers rather than being confined to a single substrate plane. The readout stack occupies the intermediate space between sensitive layers, while the interconnection stack extends to the rear face. This multi-dimensional distribution maintains compact overall dimensions while reducing thermal budget impact on sensitive layers through spatial separation.
Data Source
AI summary
An imaging device for acquiring visible and infrared images, including a visible matrix sensor, and infrared matrix sensor, and a readout integrated circuit superimposed on the visible matrix sensor and on the infrared matrix sensor and formed by a readout stack including electronic elements and an interconnection stack. The readout stack is located between the sensitive layers of the matrix sensors, and the interconnection stack is located on the rear face of the infrared matrix sensor. In addition, conductive vias electrically connect respectively the interconnection stack to electronic elements of the visible matrix sensor, to electronic elements of the readout stack, and to electronic elements of the infrared matrix sensor.