Stacked Photoelectric Conversion Elements for Deep Pixel Junctions
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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 the formation of deep photoelectric conversion elements into multiple ion implantation steps with different energies. First, high-energy ion implantation creates a deep junction, then low-energy ion implantation forms a shallow junction on top. This segmentation allows achieving deep photoelectric conversion depth without requiring a single high-energy implantation step that would increase manufacturing complexity
Solution Approach 2:
The patent introduces a temporal dimension by performing ion implantation in multiple sequential steps rather than a single step. This multi-step approach in the time dimension allows control over the depth profile of photoelectric conversion elements, achieving deep depth while managing process complexity through staged fabrication
2Measurement precision
If pixel size is decreased to increase resolution, then the resolution is improved, but the light efficiency decreases
Solution Approach 1:
The patent changes the energy parameter of ion implantation to create deep photoelectric conversion elements. By using high-energy ion implantation followed by low-energy ion implantation, the patent forms deep junctions that increase the light absorption volume within each pixel. This parameter change allows small pixels to maintain high light efficiency by capturing more photons through increased conversion depth, thus resolving the trade-off between resolution and light efficiency
3Use of energy by moving object
If deep photoelectric conversion elements are formed to increase light efficiency, then the light efficiency is improved, but the ion implantation energy requirement increases
Solution Approach 1:
The patent segments the ion implantation energy requirement into two separate steps: a high-energy step to create the deep junction and a low-energy step to form the shallow junction. This segmentation distributes the energy requirement across multiple process steps rather than requiring a single extremely high-energy implantation, making the manufacturing process more manageable while achieving deep photoelectric conversion for high light efficiency
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, essential for high-resolution imaging, 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.