Stacked Photoelectric Conversion Elements for Deep Pixel Light Capture
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Solution Overview
Problem
Current image sensing devices face challenges in achieving high light efficiency due to limitations in forming photoelectric conversion elements with deep depth, which requires high ion implantation energy, especially as pixel sizes decrease and resolution increases.
Innovation Solution
The proposed solution involves forming an image sensing device with a stacked structure of first and second photoelectric conversion elements in separate substrates, where each element is formed using different ion implantation processes with lower energy, allowing for a deep depth photoelectric conversion element without the need for high ion implantation energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If high ion implantation energy is used to form deep photoelectric conversion elements, then the depth of photoelectric conversion elements is increased, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent divides a single deep photoelectric conversion element into multiple stacked photoelectric conversion elements formed at different depths in the substrate. Each element is formed using separate ion implantation processes with lower energy levels, avoiding the need for single high-energy implantation while achieving equivalent total depth for light absorption.
Solution Approach 2:
The patent transitions from a single-depth photoelectric conversion structure to a multi-layer stacked structure in the vertical dimension. By stacking multiple photoelectric conversion elements at different depths, the system achieves deep light absorption capability without requiring high ion implantation energy for a single element.
2Measurement precision
If pixel size is decreased to increase resolution, then the resolution is improved, but the light efficiency decreases due to insufficient photoelectric conversion depth
Solution Approach 1:
The patent segments the photoelectric conversion function across multiple stacked elements at different depths within each pixel. This allows small pixels to maintain adequate light absorption capacity by distributing the conversion function vertically, compensating for the reduced pixel area while preserving resolution.
Solution Approach 2:
The patent implements nested photoelectric conversion elements where multiple conversion layers are positioned at different depths within the same pixel footprint. This nested vertical arrangement enables small pixels to capture light effectively across multiple depth levels, maintaining light efficiency despite reduced lateral dimensions.
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 light efficiency by reducing the required ion implantation energy and enabling the formation of photoelectric conversion elements with deep depth, suitable for high-resolution applications, while minimizing the height of the ion implantation mask.
Implementation Method 1
forming a first photoelectric conversion element by implanting first-type impurities into the first substrate using the first mask pattern as an ion implantation mask
Implementation Method 2
configured to generate photocharges through conversion of incident light
Data Source
AI summary
An image sensing device and a method for forming the same are disclosed. The image sensing device includes a first substrate, first photoelectric conversion elements formed in the first substrate and configured to generate photocharges in response to a reception of light, a second substrate formed over the first substrate, and second photoelectric conversion elements formed in the second substrate and configured to generate photocharges in response to a reception of light, the second photoelectric conversion elements contacting corresponding the first photoelectric conversion elements, respectively.