Stacked Transparent Oxide Semiconductor Image Sensor
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Solution Overview
Problem
Conventional CMOS image sensors face limitations in reducing pixel size due to the arrangement of light sensors on a single layer, which restricts the miniaturization of camera modules and increases production costs.
Innovation Solution
The use of a light-sensitive transparent oxide semiconductor material as a light-sensing layer, with multiple layers stacked in a pixel cell, allowing for improved color separation and reduced pixel size through chromatic aberration and complementary color filters, enabling more efficient light detection and processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If multiple light sensors are arranged on a single layer in conventional CMOS image sensors, then the manufacturing process is simplified, but the pixel size cannot be reduced further and color separation is limited
Solution Approach 1:
The patent transitions from a two-dimensional single-layer arrangement to a three-dimensional stacked configuration. Multiple light sensing layers (first, second, and third light sensing layers) are stacked vertically, allowing light sensors to be arranged in the depth dimension rather than only in the planar dimension. This enables pixel size reduction while maintaining manufacturing simplicity through standard semiconductor stacking processes.
Solution Approach 2:
The patent divides the light sensing function into multiple separate layers, each potentially optimized for different wavelengths or color channels. The first light sensing layer, second light sensing layer, and third light sensing layer are segmented independently, with each layer contributing to different aspects of color detection. This segmentation allows for improved color separation while maintaining a compact pixel structure.
2Device complexity
If multiple light sensors are arranged on a single layer, then device structure is simple, but color separation performance is insufficient
Solution Approach 1:
By stacking light sensing layers in the vertical dimension, the patent creates additional spectral discrimination capability. Each layer can be tuned to respond to different wavelength ranges, and the vertical stacking allows for independent optimization of each layer's spectral response, thereby improving color separation accuracy without significantly increasing lateral device complexity.
Solution Approach 2:
The patent employs a composite structure with multiple light sensing layers made from different materials or with different doping characteristics. Each layer is designed with specific material properties to detect different color wavelengths, creating a composite sensing system that achieves superior color separation through material diversity rather than structural complexity.
3Productivity
If pixel size is reduced to increase production per wafer, then production cost decreases, but light detection efficiency deteriorates
Solution Approach 1:
The stacked configuration allows the light sensing area to extend into the vertical dimension, effectively increasing the total light detection volume within a smaller lateral footprint. This maintains or even enhances light detection efficiency while reducing the lateral pixel size, thereby increasing the number of pixels that can be produced per wafer.
Solution Approach 2:
The patent implements a nested arrangement where multiple light sensing layers are positioned one above another, with each layer nested within the vertical space occupied by the overall pixel structure. This nested configuration maximizes the use of available space, allowing efficient light detection across multiple layers without increasing the lateral pixel dimensions, thus maintaining high detection efficiency while enabling pixel size reduction for increased productivity.
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 the reduction of pixel size beyond existing limitations, improving color separation and light detection efficiency, and potentially lowering production costs by allowing for more compact and cost-effective camera modules.
Implementation Method 1
a light-sensitive oxide semiconductor layer on the gate insulating layer... having electrical characteristics that vary according to an amount of incident light
Implementation Method 2
The at least one light-sensitive oxide semiconductor layer may have light-transmitting properties. For instance, the at least one light-sensitive oxide semiconductor layer may be transparent.
Data Source
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AI summary
An image sensor (100) includes a plurality of light-sensitive transparent oxide semiconductor layers as light-sensing layers (110,120,130), a plurality of filter layers (140,150) and a plurality of transparent insulating layers (115). The light-sensing layers may be stacked in one unit pixel region.