Image Sensor Light Guide Region for Crosstalk Reduction
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Solution Overview
Problem
In miniaturized image sensors, the reduced spacing between pixels leads to severe optical scattering noise, resulting in lower quantum efficiency, light sensitivity, and spatial resolution due to optical crosstalk, as well as color mixing and image noise.
Innovation Solution
A light guide region is formed in the substrate alongside isolation structures, with a depth greater than the isolation structures and a lower refractive index than the substrate, to block incident light from entering adjacent pixels, reducing optical crosstalk by using a separation by implanted oxygen method and forming the light guide region aside the sidewall and bottom portion of the isolation structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the spacing between pixels is reduced to achieve miniaturization, then the device size is reduced, but optical crosstalk between pixels increases
Solution Approach 1:
The patent introduces light guide regions that segment the optical path between adjacent pixels. These light guide regions act as optical isolators that divide and direct light specifically to intended pixels, preventing light from spilling into adjacent pixels. This segmentation approach allows pixels to be placed closer together while maintaining optical isolation.
Solution Approach 2:
The light guide regions serve as intermediary structures between adjacent pixels. These regions mediate the optical interaction by guiding light from the incident surface to the specific photosensitive region, preventing direct optical crosstalk between neighboring pixels. The light guide regions act as optical mediators that control light distribution in the miniaturized pixel array.
2Quantity of substance
If the spacing between pixels is reduced, then the pixel density increases, but the quantum efficiency and light sensitivity deteriorate
Solution Approach 1:
The patent applies local quality by creating light guide regions with specific optical properties (different refractive index) in localized areas between pixels. These regions have tailored optical characteristics that guide light efficiently to specific pixels while blocking crosstalk. This local modification of optical properties allows high pixel density while maintaining individual pixel sensitivity and quantum efficiency.
3Volume of moving object
If the spacing between pixels is reduced, then the device size is reduced, but the spatial resolution deteriorates
Solution Approach 1:
The light guide regions segment the optical paths to ensure that light from each incident location is directed to the correct pixel. This segmentation prevents optical crosstalk that would otherwise blur spatial information. By maintaining clear optical boundaries between pixels through light guide regions, the patent preserves spatial resolution even when pixels are densely packed in a miniaturized device.
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 increases the sensitivity and quantum efficiency of pixels, enhancing spatial resolution and overall sensitivity by preventing light from entering adjacent pixels, while being compatible with existing manufacturing processes without significant increases in cost or time.
Implementation Method 1
the index of refraction of the light guide region is less than the index of refraction of the substrate
Data Source
AI summary
A manufacturing method of an image sensor is provided. A substrate is provided, and the substrate includes a pixel array region. A plurality of openings is formed in the pixel array region of the substrate. A light guide region is formed in the substrate aside each of the openings, wherein a portion of the substrate is disposed between the light guide region and the opening, and the depth of the light guide region in the substrate is greater than the depth of the opening aside the light guide region in the substrate. Isolation structures are formed in the openings to define a plurality of pixel regions respectively located between two adjacent isolation structures in the pixel array region. A photosensitive region is formed in each of the pixel regions of the substrate. A conductive line layer is formed on each of the pixel regions of the substrate.