Nano-Pillar Image Sensor Structure for Optical Crosstalk Isolation
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Solution Overview
Problem
The challenge in image sensor technology is to minimize optical crosstalk between light sensors while achieving high-resolution images, particularly in miniaturized and integrated image sensors.
Innovation Solution
The image sensor structure incorporates a nano-pillar structure with balanced red, green, and blue photosensitive regions, separated by a transparent barrier layer and optoelectronic thin film, which improves spectral characteristics and reduces optical crosstalk through the use of a backside illumination design that isolates adjacent pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If image sensors are integrated towards high resolution and miniaturization, then resolution is improved, but optical crosstalk between light sensors increases
Solution Approach 1:
The pixel array is divided into multiple color filter regions (red, green, blue) with each region containing light sensors of corresponding wavelengths. Isolation structures are introduced between adjacent pixels to segment the optical paths, preventing crosstalk while maintaining high resolution imaging capability
Solution Approach 2:
Isolation structures including dielectric layers and reflective layers are introduced as intermediary elements between adjacent light sensors. These intermediate structures reflect or absorb stray light, preventing optical crosstalk between neighboring pixels while allowing the sensors to maintain high resolution
2Object-affected harmful factors
If isolation structures are added between pixels, then optical crosstalk is reduced, but device complexity increases
Solution Approach 1:
Multiple functions are merged into the isolation structures: dielectric layers provide both electrical isolation and optical reflection, while reflective layers simultaneously serve as part of the interconnection structure and crosstalk prevention mechanism. This integration reduces the number of separate components needed
Solution Approach 2:
The isolation structures serve multiple purposes: they provide electrical isolation between doped layers, reflect stray light to prevent crosstalk, and in some cases serve as interconnection elements. This multi-functionality reduces overall device complexity while achieving crosstalk prevention
3Manufacturing precision
If nano-pillar structure with stacked doped layers is used, then pixel photosensitive area is reduced, but manufacturing precision is improved
Solution Approach 1:
Multiple doped layers (first, second, and third doped layers with different doping types) are stacked vertically within the nano-pillar structure, with each layer nested within the same lateral footprint. This vertical nesting achieves precise doping control without increasing pixel area
Solution Approach 2:
The doping structure transitions from lateral expansion to vertical stacking. By adding the vertical dimension with multiple stacked doped layers, the patent achieves precise doping control and spectral separation without increasing the lateral pixel area, thus maintaining high resolution
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 design enhances the isolation effect between adjacent pixels, balances RGB photosensitive regions, and effectively avoids optical crosstalk, improving the filling factor and quantum efficiency of the image sensor.
Implementation Method 1
Each light sensor absorbs a part of the incident image light and generates image charges after absorbing the image light. Because the amount of image charges is proportional to the intensity of the image light
Implementation Method 2
The optoelectronic thin film structure is disposed on the transparent barrier layer and electrically connected to the interconnection layer. The optoelectronic thin film structure includes a photoconductive film portion corresponding to the nano-pillar structure
Data Source
AI summary
An image sensor structure includes a semiconductor substrate; an interconnection layer on the semiconductor substrate; nano-pillar structures, each including a first doped layer, a second doped layer and a third doped layer stacked in sequence; conductive structures, respectively electrically connected to the first doped layer and the interconnection layer, the second doped layer and the interconnection layer, and the third doped layer and the interconnection layer; a first insulating layer on the interconnection layer and wrapping the nano-pillar structures and the conductive structures, wherein the first doping layer is exposed on the first insulating layer; a transparent barrier layer on the first insulating layer; and a photoelectric thin film structure on the first insulating layer and electrically connected to the interconnection layer. The photoelectric thin film structure includes photoconductive film portions. The image sensor structure has a good isolation effect between adjacent pixels and effectively avoids optical crosstalk.