Solid-State Imaging Device Dark Current Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Solid-state imaging devices with organic or inorganic photoelectric conversion films face challenges in suppressing dark current during charge storage due to the inability to form semiconductor regions for dark current suppression at the interface of the substrate, leading to accumulated dark current.
Innovation Solution
A solid-state imaging device design where the first electrode of the photoelectric conversion element is connected to the amplifier gate electrode of the amplifier transistor but not directly to the substrate, and a voltage control circuit supplies voltage to the second electrode for charge discharge during reset, eliminating the need for direct substrate contact and thus suppressing dark current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If the first electrode is directly connected to the substrate to store signal charge, then charge storage function is achieved, but dark current accumulates at the substrate interface
Solution Approach 1:
The patent introduces a floating diffusion region as an intermediary between the first electrode and the substrate. This floating diffusion region serves as the actual charge storage location, while being electrically isolated from the substrate to prevent dark current generation. The first electrode connects to the floating diffusion region, which in turn connects to the substrate through a high-resistance path, thus mediating the connection to avoid direct contact-induced dark current.
2Object-generated harmful factors
If the first electrode is connected to the amplifier gate electrode without direct substrate contact, then dark current is suppressed, but charge storage mechanism becomes more complex
Solution Approach 1:
The patent merges the charge storage function with the amplifier gate structure by connecting the first electrode directly to the amplifier gate electrode. The floating diffusion region serves dual purposes: as the charge storage node and as the amplifier input node. This merging eliminates the need for separate charge storage and readout structures, simplifying the overall device architecture while maintaining dark current suppression.
3Ease of operation
If a voltage control circuit is used to supply voltage to the second electrode for reset, then charge discharge during reset is improved, but device complexity increases
Solution Approach 1:
The voltage control circuit connected to the second electrode serves multiple functions: it provides the primary voltage bias for the photoelectric conversion element during normal operation, and it enables the reset function by supplying a reset voltage to discharge accumulated charge. This multi-functional design eliminates the need for separate bias and reset control circuits, reducing overall device complexity while improving ease of operation.
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 design effectively reduces dark current noise by preventing direct contact between the first electrode and the substrate, allowing for improved charge storage and reset operations without accumulating dark current.
Implementation Method 1
a photoelectric conversion film 19 made of an organic material or an inorganic material and generating a signal charge according to the quantity of incident light
Data Source
AI summary
A solid-state imaging device includes a substrate, a photoelectric conversion element provided on the light incidence side of the substrate and including a photoelectric conversion film sandwiched between a first electrode provided separately for each of pixels, and a second electrode provided opposite the first electrode, the photoelectric conversion film being made of an organic material or an inorganic material and generating a signal charge according to the quantity of incident light, an amplifier transistor having an amplifier gate electrode connected to the first electrode, and a voltage control circuit that is connected to the second electrode, and supplies a desired voltage to the second electrode.