Silicon Nitride Insulating Layer Coupling for Dark Current Suppression
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Solution Overview
Problem
In imaging devices, optical black (OB) pixels experience higher dark current levels due to incomplete hydrogen sintering processing, as they are covered by the light blocking member, making it difficult to lower the interface state and reduce dark current effectively.
Innovation Solution
Forming the same silicon nitride insulating layer over both effective and OB pixels, allowing for coupling between these layers, which reduces dark current without the need for an additional hydrogen diffusion preventing film, simplifying the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hydrogen diffusion preventing film is formed between the hydrogen supply film and light blocking member in the OB pixel, then the dark current level in OB pixel is suppressed, but the manufacturing process becomes cumbersome
Solution Approach 1:
The patent merges the light blocking member and hydrogen diffusion preventing film into a single integrated structure. The light blocking member is configured to simultaneously block light and prevent hydrogen diffusion, eliminating the need for a separate hydrogen diffusion preventing film layer. This integration maintains dark current suppression functionality while simplifying the manufacturing process by reducing the number of fabrication steps and material layers required.
2Object-affected harmful factors
If the OB pixel is covered by a light blocking member, then light blocking functionality is achieved, but hydrogen sintering processing effect is reduced and dark current increases
Solution Approach 1:
The light blocking member is designed with dual functionality: it blocks incident light from reaching the OB pixel while simultaneously serving as a hydrogen diffusion barrier. By integrating these two functions into a single component, the patent ensures that OB pixels receive adequate hydrogen supply for sintering processing while maintaining their light-blocking capability, thereby reducing dark current without compromising light blocking performance.
Solution Approach 2:
The light blocking member is transformed into a multi-functional element that performs both light blocking and hydrogen diffusion prevention. This universal design allows a single structure to address multiple technical requirements, eliminating the need for additional specialized layers and simplifying the overall device architecture while maintaining both light blocking effectiveness and dark current suppression.
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 effectively lowers the dark current in OB pixels by utilizing the existing antireflection film, eliminating the requirement for a new layer and simplifying the manufacturing process, while maintaining the light-blocking functionality of OB pixels.
Implementation Method 1
a hydrogen supply film and a light blocking member in the OB pixel. The hydrogen diffusion preventing film prevents outward diffusion of hydrogen supplied from the hydrogen supply film
Implementation Method 2
The effective pixel is a pixel that receives incident light and obtains an electrical charge by a photoelectric effect
Implementation Method 3
hydrogen sintering processing may be performed after an uppermost wiring layer is formed. By this hydrogen sintering processing, a dangling-bond, which is an uncombined hand, generated in a gate insulating layer or the dike is terminated by hydrogen
Data Source
AI summary
An imaging device and a manufacturing method of the imaging device are provided, which can lower the level of a dark current in an optical black pixel without forming a new layer such as a hydrogen diffusion preventing film.Both of an insulating layer over a photodiode arranged over an effective pixel region and an insulating layer over a photodiode arranged over an OB pixel region include silicon nitride, are formed of the same layer, and are coupled with each other.