Stacked Image Sensor Light Shielding for Hot Carrier Luminescence
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Solution Overview
Problem
Solid state imaging devices face challenges in achieving high-speed signal transmission due to the close proximity of photoelectric conversion units and peripheral circuits, which leads to noise interference from heat and electromagnetic fields, and hot carrier luminescence affecting image quality.
Innovation Solution
A light shielding member is strategically placed between the pixel region and the peripheral circuit unit to shield light emitted from active elements, reducing noise interference and improving image quality by minimizing the infiltration of hot carrier luminescence into photoelectric conversion units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If photoelectric conversion units and peripheral circuits are arranged in close proximity to achieve miniaturization, then device size is reduced, but noise interference from heat and electromagnetic fields increases
Solution Approach 1:
The device is divided into distinct functional regions: a pixel region containing photoelectric conversion units and a peripheral circuit region containing signal processing circuits. This spatial segmentation allows miniaturization while maintaining functional separation to reduce noise interference between regions.
Solution Approach 2:
A light shielding member is introduced as an intermediary structure between the pixel region and peripheral circuit region. This mediator blocks hot carrier luminescence and electromagnetic noise from the peripheral circuits from reaching the photoelectric conversion units, enabling close proximity arrangement without compromising image quality.
2Speed
If signal processing circuits are integrated close to photoelectric conversion units, then transmission distance is reduced for high-speed connection, but hot carrier luminescence from transistors affects image quality
Solution Approach 1:
A light shielding member is positioned between the peripheral circuit region and pixel region to block hot carrier luminescence from transistors in the signal processing circuits from reaching the photoelectric conversion units. This intermediary structure enables short transmission distances for high-speed signaling while preventing luminescence-induced image degradation.
Solution Approach 2:
The harmful effect of hot carrier luminescence is extracted and blocked by the light shielding member, separating the beneficial function of close circuit integration from its harmful side effect. This allows the circuit arrangement to maintain short transmission distances while removing the luminescence interference.
3Volume of moving object
If multiple chips are combined in one package using SIP technique for miniaturization, then device size is reduced, but transmission distance increases making high-speed connection difficult
Solution Approach 1:
Multiple functional regions (pixel region and peripheral circuit region) are merged into a single integrated device structure on one semiconductor substrate. This combination achieves miniaturization while keeping signal transmission distances short, enabling high-speed connections without requiring multiple separate chips in a package.
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
The implementation of a light shielding member effectively suppresses the infiltration of light from active elements, enhancing the image quality of solid state imaging devices by reducing noise interference and improving signal transmission efficiency.
Implementation Method 1
a light shielding member that is formed between the pixel region and the peripheral circuit unit and that shields the incidence of light, emitted from an active element, to the photoelectric conversion units
Implementation Method 2
a pixel region that is formed on a light incidence side of a substrate and to which a plurality of pixels that include photoelectric conversion units is arranged
Data Source
AI summary
A solid state imaging device including: a pixel region that is formed on a light incidence side of a substrate and to which a plurality of pixels that include photoelectric conversion units is arranged; a peripheral circuit unit that is formed in a lower portion in the substrate depth direction of the pixel region and that includes an active element; and a light shielding member that is formed between the pixel region and the peripheral circuit unit and that shields the incidence of light, emitted from an active element, to the photoelectric conversion unit.