Concentric Loop Fresnel Zone Plate for Image Sensor Light Focusing
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Solution Overview
Problem
Conventional image-sensing devices have limited quantum efficiency and sensitivity due to the inability of microlenses to focus incident light into a deep region of the photo-sensing elements, restricting the effectiveness of pixel cells.
Innovation Solution
An image-sensing device featuring a semiconductor substrate with a photo-sensing element, a passive layer, and a light-collecting element comprising concentric loops with varying refractive indices and widths, which acts as a Fresnel zone plate to focus incident light deeper into the photo-sensing element, improving light collection and sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional microlens structure is used, then light focusing capability is achieved, but the device vertical size is larger
Solution Approach 1:
The conventional microlens mechanical structure is replaced with a planar light-collecting element comprising concentric loops with different refractive indices. This substitution maintains the light focusing capability through optical refractive index variation while dramatically reducing the vertical dimension, as the new structure operates in a planar configuration rather than requiring a three-dimensional lens profile.
Solution Approach 2:
The light focusing function is transitioned from a three-dimensional microlens structure to a two-dimensional planar structure with concentric loops. By utilizing refractive index variation within the planar loops rather than relying on vertical curvature, the device achieves light focusing capability while minimizing vertical size, effectively moving the solution from vertical dimension to planar dimension.
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 solution enhances the quantum efficiency and sensitivity of the image-sensing device by effectively focusing more incident light into the photo-sensing element, while also reducing the device's vertical size compared to conventional designs, allowing for a more compact structure.
Implementation Method 1
The first, second, and third loops comprise different refractive indices
Implementation Method 2
the light-collecting element acts as a Fresnel zone plate to focus incident light deeper into the photo-sensing element
Implementation Method 3
The semiconductor substrate comprises a photo-sensing element
Data Source
AI summary
An image-sensing device includes a semiconductor substrate, a passive layer, and a light-collecting element. The semiconductor substrate includes a photo-sensing element, and the passive layer is disposed over the semiconductor substrate. The light-collecting element is disposed over the passive layer, and includes first, second and third loops. The first loop has a first width. The second loop surrounds the first loop and has a second width that is less than the first width. The third loop surrounds the first and second loops, and has a third width that is less than the second width. The light-collecting element aligns with the photo-sensing element, and the first, second, and third loops include different refractive indices.