Stacked Pixel Lens Structure for Low-Crosstalk Image Sensors
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Solution Overview
Problem
As feature sizes in image sensor devices decrease, improving light collection efficiency becomes increasingly challenging, making it difficult to form devices with high light collection efficiency at smaller sizes.
Innovation Solution
The formation of an image sensor device involves a semiconductor substrate with isolation structures and light-blocking structures to reduce optical crosstalk, combined with a grid layer and lenses to enhance light collection, where the lenses are formed over the light-sensing regions to direct incident light and improve efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If feature sizes are reduced to increase functional density, then the number of interconnected devices per chip area increases, but light collection efficiency deteriorates
Solution Approach 1:
The patent implements a nested lens structure where a first lens and a second lens are positioned one over the other at different heights above the pixel array. The first lens has a larger diameter and is positioned closer to the pixel array, while the second lens has a smaller diameter and is positioned higher. This nested configuration allows both lenses to work together to collect and focus light onto the same photosensitive region, thereby maintaining high light collection efficiency even as feature sizes are reduced to increase functional density.
Solution Approach 2:
The patent addresses the light collection challenge by introducing a vertical dimension to the lens system. Instead of relying solely on a single planar lens, the invention stacks lenses at different heights above the pixel array, utilizing the third dimension (vertical space) to enhance light gathering capability. This multi-level lens arrangement allows light from different angles and positions to be effectively directed onto the photosensitive region, compensating for the reduced light collection area caused by smaller feature sizes.
2Volume of moving object
If feature sizes are reduced, then device miniaturization is achieved, but light collection efficiency becomes more difficult to improve
Solution Approach 1:
The patent implements a nested lens structure where a first lens and a second lens are positioned one over the other at different heights above the pixel array. The first lens has a larger diameter and is positioned closer to the pixel array, while the second lens has a smaller diameter and is positioned higher. This nested configuration allows both lenses to work together to collect and focus light onto the same photosensitive region, thereby maintaining high light collection efficiency even as feature sizes are reduced to increase functional density.
Solution Approach 2:
The patent addresses the light collection challenge by introducing a vertical dimension to the lens system. Instead of relying solely on a single planar lens, the invention stacks lenses at different heights above the pixel array, utilizing the third dimension (vertical space) to enhance light gathering capability. This multi-level lens arrangement allows light from different angles and positions to be effectively directed onto the photosensitive region, compensating for the reduced light collection area caused by smaller feature sizes.
3Device complexity
If a single lens is used, then device complexity is low, but light collection efficiency is insufficient at smaller sizes
Solution Approach 1:
The patent implements a nested lens structure where a first lens and a second lens are positioned one over the other at different heights above the pixel array. The first lens has a larger diameter and is positioned closer to the pixel array, while the second lens has a smaller diameter and is positioned higher. This nested configuration allows both lenses to work together to collect and focus light onto the same photosensitive region, thereby maintaining high light collection efficiency even as feature sizes are reduced to increase functional density.
Solution Approach 2:
The patent addresses the light collection challenge by introducing a vertical dimension to the lens system. Instead of relying solely on a single planar lens, the invention stacks lenses at different heights above the pixel array, utilizing the third dimension (vertical space) to enhance light gathering capability. This multi-level lens arrangement allows light from different angles and positions to be effectively directed onto the photosensitive region, compensating for the reduced light collection area caused by smaller feature sizes.
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 described structure enhances light collection efficiency by reducing optical crosstalk and effectively directing incident light to the light-sensing regions, improving the performance of image sensor devices at smaller sizes.
Implementation Method 1
a first lens and a second lens over the first lens, the first lens being able to direct incident light passing through the second lens to a light-sensing region under the first lens
Data Source
AI summary
An image sensor device is provided. The image sensor device includes a substrate. The image sensor device includes a light-sensing region in the substrate. The image sensor device includes an isolation structure in the substrate. The isolation structure surrounds the light-sensing region. The image sensor device includes a grid layer over the substrate. The grid layer is over the isolation structure. The image sensor device includes a first lens over the light-sensing region and surrounded by the grid layer. The image sensor device includes a color filter layer over and in direct contact with the first lens. The first lens is embedded in the color filter layer. The image sensor device includes a second lens over the color filter layer.