Semiconductor Contact Plug for Solid-State Imaging Noise Reduction
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Solution Overview
Problem
Conventional solid-state imaging devices experience increased noise due to crystal defects at the contact interface between the charge accumulation region and metal plugs caused by silicon alloying reactions.
Innovation Solution
A solid-state imaging device using a semiconductor material for the contact plug to directly connect the photoelectric conversion unit and charge accumulation region, preventing alloying reactions and reducing crystal defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal plugs are used to connect the photoelectric conversion film to the charge accumulation region, then electrical connection is achieved, but crystal defects increase due to silicon alloying reactions at the contact interface
Solution Approach 1:
A semiconductor layer is introduced as an intermediary between the metal plug and the charge accumulation region. This semiconductor layer acts as a mediator that prevents direct contact between metal and silicon, thereby eliminating the silicon alloying reaction that causes crystal defects and noise, while still enabling electrical connection through the intermediate semiconductor material.
2Device complexity
If the photoelectric conversion film is stacked on the top of wiring layers, then integration is achieved, but charges must be transmitted through metal plugs causing noise
Solution Approach 1:
The semiconductor layer serves as an intermediary that replaces the need for metal plugs in transmitting charges from the photoelectric conversion film to the charge accumulation region. This eliminates the noise-generating alloying reaction at the metal-silicon interface while maintaining the layered structure integration.
3Use of energy by moving object
If conventional layered structure with metal plugs is used, then photoelectric conversion is achieved, but noise increases due to alloying reactions at contact interfaces
Solution Approach 1:
The semiconductor layer is positioned between the metal plug and the charge accumulation region, acting as a mediator that enables photoelectric conversion to occur while preventing the harmful alloying reaction. This intermediary layer allows charges generated by photoelectric conversion to be transmitted to the charge accumulation region without the noise-generating interface reactions.
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 decreases noise by eliminating alloying reactions at the contact interface, enhancing the imaging device's performance by reducing crystal defects and leakage current.
Implementation Method 1
a photoelectric converter which converts light into signal charges
Data Source
AI summary
An imaging device includes: a photoelectric converter which converts light into signal charges; a charge accumulation region which is electrically connected to the photoelectric converter, and accumulates the signal charges; a transistor having a gate electrode which is electrically connected to the charge accumulation region; and a contact plug which electrically connects the photoelectric converter to the charge accumulation region, is in direct contact with the charge accumulation region, and comprises a semiconductor material.