Solid-State Imaging Charge Transport via Segmented Impurity Layers
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Solution Overview
Problem
Conventional solid-state imaging apparatuses face inefficiencies in charge transport from photodiodes to floating diffusion due to the depth and structure of impurity layers, affecting light sensitivity across different wavelengths.
Innovation Solution
The implementation of a first impurity layer with a constant depth and a second impurity layer that becomes shallower in the direction of charge transport, along with a third impurity layer spaced apart, enhances charge transport efficiency and maintains consistent light sensitivity across wavelengths by forming a wider depletion layer and optimizing the potential gradient.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If an n impurity layer is formed deep in a stair-like manner through multiple ion implantation to improve charge transport efficiency, then charge transport efficiency is improved, but manufacturing complexity and process time increase
Solution Approach 1:
The impurity layer is divided into multiple regions with different depths: a first impurity layer at a constant depth and a second impurity layer that becomes shallower in the charge transport direction. This segmentation allows the formation of a stair-like potential structure through single ion implantation processes rather than multiple sequential implantations, reducing manufacturing complexity while maintaining improved charge transport efficiency.
Solution Approach 2:
The patent changes the depth parameter of the impurity layer from a uniform deep structure to a variable depth structure where the second impurity layer becomes shallower toward the charge transport direction. This parameter change creates the desired stair-like potential gradient that improves charge transport while being achievable through optimized single ion implantation processes rather than multiple implantations.
2Productivity
If an n impurity layer is formed deep in a stair-like manner through multiple ion implantation to improve charge transport, then charge transport efficiency is improved, but manufacturing time increases
Solution Approach 1:
The impurity layer is segmented into first and second regions with different depth characteristics. This segmentation enables the creation of a stair-like potential structure that improves charge transport efficiency while being formable through single ion implantation processes, thereby reducing the total manufacturing time compared to multiple sequential implantation approaches.
Solution Approach 2:
The patent designs the impurity layer depth profile in advance such that the second impurity layer is positioned to become shallower in the charge transport direction. This preliminary design allows the desired stair-like potential structure to be achieved through optimized single ion implantation, eliminating the need for multiple implantation steps and reducing manufacturing time.
3Productivity
If a deep impurity layer structure is used to improve charge transport, then charge transport efficiency is improved, but light sensitivity consistency across wavelengths deteriorates
Solution Approach 1:
The patent applies local quality by creating different impurity layer depths in different spatial regions: a first impurity layer at a constant depth and a second impurity layer that becomes shallower toward the charge transport direction. This local variation in impurity depth creates a stair-like potential structure that improves charge transport efficiency while maintaining consistent light sensitivity across different wavelengths by preserving adequate photoelectric conversion volume.
Solution Approach 2:
The patent changes the depth parameter of the impurity layer from uniform to variable, with the second impurity layer becoming shallower in the charge transport direction. This parameter change creates the stair-like potential gradient that enhances charge transport while maintaining consistent optical response across wavelengths by ensuring sufficient photoelectric conversion volume throughout the structure.
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 configuration improves charge transport efficiency and maintains consistent light sensitivity for visible light across wavelengths, addressing the limitations of conventional designs.
Implementation Method 1
a photodiode which generates a certain amount of electrical charges based on an amount of light irradiation
Implementation Method 2
This n impurity layer is formed through a plurality of times of ion implantation
Data Source
AI summary
Certain embodiments provide a solid-state imaging apparatus including a first impurity layer, a second impurity layer, a third impurity layer, and an electrode. The first impurity layer is a photoelectric conversion layer, and is formed to have a constant depth on a semiconductor substrate. The second impurity layer is formed on a surface of the first impurity layer, to have a depth which becomes shallower toward a direction from the first impurity layer to the third impurity layer. The third impurity layer is formed in a position spaced apart from the first impurity layer and the second impurity layer on the surface of the semiconductor substrate. The electrode can transport electric charges from the first impurity layer to the third impurity layer, and is formed between the second impurity layer and the third impurity layer, on the surface of the semiconductor substrate.