Dual-Band Image Sensor Layout Without Middle-Layer Contacts
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing dual-band image sensors face challenges in fabrication complexity, low yield, and scalability issues, particularly in simultaneous mode operations, and are not compatible with unipolar two-color designs using thin barrier layers.
Innovation Solution
A method for fabricating simultaneous dual-band image sensors with a simpler process involves forming a common ground substrate, layering absorber and diode layers, and creating ring openings to define contacts for each band, allowing for independent and simultaneous signal collection from both bands without requiring middle layer contacts or dopant implantation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a simultaneous dual-band image sensor is fabricated using prior art methods with middle layer contacts or dopant implantation, then dual-band sensing capability is achieved, but fabrication complexity increases and yield decreases
Solution Approach 1:
The patent removes the middle layer contact structure from the device architecture. By eliminating this intermediate contact layer, the fabrication process is simplified and yield is improved, while still achieving simultaneous dual-band sensing through the use of two separate bump contacts on the top layer that directly access the nBn regions for each band.
Solution Approach 2:
The device is segmented into distinct functional regions with separate nBn structures for Band 1 and Band 2, each with its own contact region. This segmentation allows independent optimization of each band's sensing path and simplifies the overall fabrication by avoiding complex inter-layer connections.
2Adaptability or versatility
If two or three bumps are required per pixel for simultaneous mode operation, then both bands can be sensed simultaneously, but fabrication becomes very challenging
Solution Approach 1:
The patent merges the contact structure into a single top layer where both Band 1 and Band 2 contacts are formed. Instead of requiring separate middle layer contacts for each band, the design uses two bump contacts on the top layer that access the respective nBn regions, simplifying the manufacturing process while maintaining simultaneous dual-band capability.
3Manufacturing precision
If dopant implantation or middle layer contact steps are used, then electrical connection is achieved, but scalability to reduced pitch size or increased format size is hampered
Solution Approach 1:
The patent extracts the middle layer contact step from the fabrication process. By forming contacts only on the top layer through simple bump formation and etching, the process becomes scalable to smaller pitch sizes and larger format sizes without the complications of aligning and forming contacts through multiple layers.
4Ease of manufacture
If traditional photodiode detectors are used, then established fabrication processes can be employed, but unipolar two-color designs with thin barrier layers cannot be implemented
Solution Approach 1:
The patent changes the detector type from traditional photodiodes to unipolar nBn detectors with thin barrier layers. This parameter change enables new functionality for simultaneous dual-band operation while the simplified contact structure (without middle layers) makes the fabrication equally accessible to manufacturers familiar with traditional processes.
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 enables scalable, high-yield production of dual-band image sensors that can operate simultaneously, improving fabrication simplicity and compatibility with unipolar designs, allowing for efficient collection of signals from two electromagnetic bands.
Implementation Method 1
forming a Band 1 absorber layer on the common ground layer, forming a barrier layer on the Band 1 absorber layer, forming a Band 2 absorber layer on the barrier layer
Data Source
AI summary
A simultaneous dual-band image sensor having a plurality of pixels includes a substrate, a common ground on the substrate, wherein each pixel includes a Band 1 absorber layer on the common ground layer, a barrier layer on the Band 1 absorber layer, a Band 2 absorber layer on the barrier layer, a ring opening in the pixel formed by a removed portion of the Band 2 absorber layer, a removed portion of the barrier layer and a removed portion of the Band 1 absorber layer, wherein the ring opening does not extend through the Band 1 absorber layer, a first contact on a portion of the Band 2 absorber layer inside the ring, and a second contact on a portion of the Band 2 absorber layer outside the ring. The Band 1 absorber layer and the Band 2 absorber layer are n-type, or the Band 1 absorber layer and the Band 2 absorber layer are p-type.