Termination Layer for Charge Transfer in Semiconductor Imaging
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Solution Overview
Problem
Conventional semiconductor devices experience noise and afterimage issues due to interface levels acting as charge traps between the silicon substrate and photoelectric conversion layers, which hinder complete charge transfer and result in suboptimal signal quality.
Innovation Solution
A semiconductor device with a stacked structure comprising a silicon substrate, a photoelectric conversion layer, a termination layer, and an electrode layer, where the termination layer terminates dangling bonds on the silicon substrate, allowing complete charge transfer and reducing noise by preventing charge mixing between pixel regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a photoelectric conversion film is connected to a floating diffusion region via a semiconductor region and transfer transistor, then charge transfer is enabled, but noise due to capacitance of the floating diffusion region occurs
Solution Approach 1:
A termination layer is introduced as an intermediary between the silicon substrate and the photoelectric conversion layer. This termination layer terminates dangling bonds at the silicon substrate surface, preventing interface levels from acting as charge traps, thereby enabling complete charge transfer without the noise problem associated with floating diffusion regions
Solution Approach 2:
The invention eliminates the floating diffusion region from the charge transfer path by using a stacked structure where the photoelectric conversion layer directly contacts the silicon substrate through the termination layer. This extraction of the problematic floating diffusion region removes the source of capacitance-induced noise while maintaining charge transfer functionality
2Reliability
If interface levels act as charge traps between silicon substrate and photoelectric conversion layers, then charge transfer is hindered, but adding termination layer increases structural complexity
Solution Approach 1:
The termination layer changes the electrical parameters at the silicon substrate surface by terminating dangling bonds. This parameter change eliminates interface levels that would otherwise act as charge traps, improving signal quality without requiring complex additional structures beyond the necessary layered configuration
3Object-generated harmful factors
If correlated double sampling is used to eliminate noise, then noise reduction is attempted, but noise is not completely eliminated from read signals
Solution Approach 1:
Instead of attempting to eliminate noise after signal reading through correlated double sampling, the invention takes preliminary action by preventing noise generation at the source. The termination layer is positioned to prevent charge mixing at the interface before charge transfer occurs, thereby eliminating noise at its origin rather than attempting post-processing removal
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
The solution effectively reduces noise and afterimages by ensuring complete charge transfer from the photoelectric conversion layer to the silicon substrate, enhancing signal quality and aperture ratio in imaging devices.
Implementation Method 1
a photoelectric conversion layer 20, a termination layer 22... The photoelectric conversion layer 20 is disposed on a first surface side of the silicon substrate 16
Implementation Method 2
The termination layer 22 is disposed between the silicon substrate 16 and the photoelectric conversion layer 20, in contact with the first surface of the silicon substrate 16, and to terminate dangling bonds of the silicon substrate 16
Data Source
AI summary
According to an embodiment, a semiconductor device includes a silicon substrate, a photoelectric conversion layer, a termination layer, and an electrode layer. In the silicon substrate, first semiconductor regions and second semiconductor regions are alternately arranged along a first surface on a light incident side of the silicon substrate. The first semiconductor regions are doped with impurities of first concentration and have a conductivity of either one of p-type and n-type. The second semiconductor regions are doped with impurities of a second concentration lower than the first concentration and have a conductivity of the other type. The photoelectric conversion layer is disposed on a first surface side of the silicon substrate. The termination layer is disposed between the silicon substrate and the photoelectric conversion layer, in contact with the first surface, and to terminate dangling bonds of the silicon substrate. The electrode layer is provided on the light incident side.