Solid-State Imaging Device Charge Leakage Prevention
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Solution Overview
Problem
In solid-state imaging devices with stacked substrates, incomplete charge transfer and kTC noise persist due to charges flowing into electrodes during charge accumulation in the photoelectric conversion layer.
Innovation Solution
A solid-state imaging device design featuring a first substrate with a photoelectric conversion part, a first insulating film, a first electrode, a second electrode, and an impurity ion diffusion region, where the impurity ion diffusion region is disposed in the depth direction of the photoelectric conversion part to prevent charge flow into electrodes during accumulation, and a semiconductor layer with a wider band gap is optionally included to enhance charge transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an insulating film and storage electrode are arranged below the photoelectric conversion layer to accumulate charge, then charge transfer efficiency is improved, but some charges flow into the lower electrode during accumulation
Solution Approach 1:
A blocking layer is introduced as an intermediary component between the insulating film and the lower electrode. This blocking layer prevents charges from leaking into the lower electrode while allowing the insulating film to accumulate charges effectively, thus resolving the contradiction between charge transfer efficiency and charge leakage prevention
Solution Approach 2:
The structure is segmented by dividing the charge accumulation region into distinct functional layers: the insulating film for charge accumulation and the blocking layer for charge prevention. This segmentation allows each layer to perform its specific function optimally without interference
2Speed
If the photoelectric conversion layer is made thinner to improve charge transfer, then charge transfer speed increases, but charge accumulation efficiency decreases
Solution Approach 1:
The thickness and material properties of the insulating film are optimized to compensate for the reduced photoelectric conversion layer thickness. By adjusting the dielectric constant and thickness of the insulating film, sufficient charge accumulation is achieved even with a thinner photoelectric conversion layer, maintaining both speed and 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
The solution effectively prevents charge flow into electrodes during accumulation, reducing noise and improving charge transfer efficiency in solid-state imaging devices.
Implementation Method 1
an impurity ion diffusion region disposed facing the second electrode and disposed in a depth direction of the photoelectric conversion part from an interface between the photoelectric conversion part and the first insulating film
Implementation Method 2
a first insulating film that is disposed closer to the second substrate than the photoelectric conversion part and accumulates and transfers charge photoelectric-converted by the photoelectric conversion part
Data Source
AI summary
To prevent a part of charges from flowing into an electrode during accumulation of photoelectric-converted charges. A solid-state imaging device including a first substrate that performs photoelectric conversion and a second substrate that reads photoelectric-converted photocurrent, the first substrate and the second substrate being stacked, in which the first substrate includes: a photoelectric conversion part; a first insulating film that is disposed closer to the second substrate than the photoelectric conversion part and accumulates and transfers charge photoelectric-converted by the photoelectric conversion part; a first electrode disposed closer to the second substrate than the first insulating film and disposed facing the photoelectric conversion part; a second electrode disposed closer to the second substrate than the first insulating film and disposed apart from the first electrode; and an impurity ion diffusion region disposed facing the second electrode and disposed in a depth direction of the photoelectric conversion part from an interface between the photoelectric conversion part and the first insulating film.