Sensitized Semiconductor Diode Image Sensors
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Solution Overview
Problem
Conventional image sensors face challenges in achieving high sensitivity, small pixel sizes, and efficient light absorption across various wavelengths due to limitations in optically sensitive materials and pixel architectures, leading to issues with crosstalk and noise.
Innovation Solution
The integration of optically sensitive nanocrystals, such as quantum dots, with semiconductor substrates and pixel circuits that utilize non-metallic contact regions and light-blocking layers to enhance light absorption and reduce crosstalk, allowing for direct electrical communication between the optically sensitive material and charge stores.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional image sensors use traditional optically sensitive materials and pixel architectures, then manufacturing and operation are simpler, but sensitivity is limited and pixel sizes cannot be reduced further due to crosstalk and noise issues
Solution Approach 1:
The pixel architecture is segmented into distinct functional layers: optically sensitive material layer, charge store layer, and readout circuit layer. This vertical segmentation allows each layer to be optimized independently, enabling reduced pixel sizes without increasing lateral complexity, thereby improving sensitivity while managing device complexity.
Solution Approach 2:
The patent transitions from lateral pixel differentiation to vertical layering. By stacking functional layers vertically (optically sensitive material above charge store above readout circuit), the design achieves higher sensitivity and smaller pixel footprints without proportionally increasing overall device complexity, as the vertical arrangement consolidates functions that would otherwise require lateral expansion.
2Area of stationary object
If pixel sizes are reduced to increase sensor resolution, then more pixels fit in the same area, but crosstalk between adjacent pixels increases and noise levels rise
Solution Approach 1:
The charge store is spatially segmented from the readout circuit by placing them in separate vertical layers. This segmentation creates physical isolation between adjacent pixels' charge storage regions, reducing lateral crosstalk even when pixels are closely packed, thereby enabling higher sensor area utilization without proportionally increasing harmful interference.
Solution Approach 2:
A dielectric layer is introduced as an intermediary between the optically sensitive material and the charge store. This intermediary layer acts as an electrical isolation barrier that prevents charge leakage and reduces noise coupling between adjacent pixels, allowing smaller pixel sizes without compromising signal integrity.
3Measurement precision
If non-metallic contact regions are used between optically sensitive material and charge stores, then light absorption efficiency improves and crosstalk is reduced, but electrical communication pathways become more complex
Solution Approach 1:
A dielectric material serves as an intermediary between the optically sensitive material and the charge store. This dielectric layer is transparent to light, allowing photons to pass through to the charge store while providing electrical isolation that reduces crosstalk. The electrical connection is established through controlled interfaces at the boundaries of the dielectric layer, managing complexity through precise interface engineering rather than complex bulk structures.
Solution Approach 2:
The contact region between optically sensitive material and charge store is engineered with local variations in dielectric properties and thickness. By optimizing the local electrical and optical properties at the interface, the design achieves efficient charge transfer and light absorption without requiring complex global structures, thereby improving performance while controlling overall device complexity.
4Object-affected harmful factors
If light-blocking layers are added to reduce crosstalk, then noise from adjacent pixels is reduced, but the device structure and manufacturing processes become more complex
Solution Approach 1:
The light-blocking function is merged with the dielectric layer that already serves as an electrical isolation barrier between the optically sensitive material and charge store. By combining optical blocking and electrical isolation functions into a single layer, the design reduces crosstalk noise without adding separate manufacturing steps, thereby improving ease of manufacture while achieving the desired noise reduction.
Solution Approach 2:
The dielectric layer is designed to perform multiple functions simultaneously: electrical isolation, optical transparency to desired wavelengths, and light blocking to prevent crosstalk. This multi-functionality eliminates the need for separate dedicated light-blocking layers, simplifying the overall device structure and manufacturing process while effectively reducing inter-pixel interference.
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 high sensitivity, small pixel sizes, and efficient light absorption across a wide spectral range while minimizing crosstalk and noise, resulting in improved image sensor performance with increased dynamic range and fill factor.
Implementation Method 1
efficient light absorption across a wide spectral range
Implementation Method 2
optically sensitive material, such as nanocrystals or other optically sensitive material
Data Source
AI summary
An image sensor device includes a semiconductor substrate, including an array of pixel circuits, which define respective pixels of the device. A photosensitive layer is formed over the semiconductor substrate and configured to transfer charge to the pixel circuits in response to light incident on the photosensitive layer. An upper layer is formed over the photosensitive layer and is at least partially transparent to the light. Opaque partitions extend vertically through the upper layer in a checkerboard pattern aligned with the pixels in the array.