Solid-State Imaging Device Charge Storage Segmentation
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Solution Overview
Problem
Solid-state imaging devices with photoelectric conversion layer stack configurations are prone to failure when excessive light is incident, leading to burn-in and potential breakdown due to excessive voltage applied to the floating diffusion, regardless of whether holes or electrons are stored in charge storage portions made from impurity layers in the silicon substrate.
Innovation Solution
The device incorporates a charge storage portion with a first and second charge storage region and a separation/connection region in the semiconductor substrate, where holes or electrons are stored differently based on the potential, with the separation/connection region electrically connecting or separating these regions depending on the voltage level, preventing excessive storage in the second charge storage region and thus avoiding potential breakdown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If holes are stored in a charge storage portion made from a p-type impurity layer, then sensitivity is maintained and spectral sensitivity is prevented from broadening, but device failure occurs under excessive light conditions due to potential breakdown
Solution Approach 1:
The charge storage portion is divided into multiple charge storage regions with different potentials. The first charge storage region has a higher potential and the second charge storage region has a lower potential, allowing selective storage of holes based on light intensity. This segmentation prevents excessive charge accumulation in a single region, thereby avoiding breakdown while maintaining sensitivity.
Solution Approach 2:
The invention introduces a dynamic potential control mechanism where the potential of the first charge storage region is set higher than that of the second charge storage region. This dynamic potential difference enables the system to adaptively respond to varying light conditions, directing excess holes to the first region under high light intensity while maintaining normal operation in the second region under standard conditions.
2Device complexity
If a single charge storage region is used, then device structure is simple, but excessive charge accumulation causes breakdown and failure
Solution Approach 1:
The charge storage portion is segmented into multiple charge storage regions (first and second regions) with different potentials. This segmentation distributes the charge storage function across multiple regions, preventing excessive charge accumulation in any single region and thereby avoiding breakdown while maintaining reasonable structural complexity.
Solution Approach 2:
The invention pre-establishes multiple charge storage regions with different potentials before operation. This preliminary configuration enables the system to handle excessive light conditions proactively by providing alternative storage paths, rather than reacting to breakdown conditions after they occur.
3Reliability
If multiple charge storage regions with different potentials are used, then reliability under excessive light is improved, but device complexity increases
Solution Approach 1:
The charge storage portion is divided into a first charge storage region and a second charge storage region with different potentials. This segmentation provides the reliability benefit of preventing breakdown under excessive light by distributing charge storage, while keeping the structural complexity manageable through a clear two-region architecture.
Solution Approach 2:
Different regions of the charge storage portion are assigned different potentials (first region with higher potential, second region with lower potential). This local quality differentiation enables each region to serve a specific function in handling different light intensity conditions, improving reliability while maintaining a systematic and manageable structure.
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 configuration prevents failure and burn-in even under excessive light conditions by ensuring that the potential of the second charge storage region does not exceed a critical value, maintaining device integrity and output quality.
Implementation Method 1
a photoelectric conversion layer stack type solid-state imaging device having a photoelectric conversion portion which is disposed above a silicon substrate and which includes a pair of electrodes and a photoelectric conversion layer sandwiched between the pair of electrodes
Implementation Method 2
A bias voltage (about 5V to 20V, for example, 10V) higher than a power supply voltage VDD (for example, 3V) supplied to the reading circuit is applied to the counter electrode 2 shown in FIG. 14. The bias voltage generates an electric field between the pixel electrode 1 and the counter electrode 2. By the electric field, holes of electric charges generated in the photoelectric conversion layer 3 are moved to the pixel electrode 1
Data Source
AI summary
The invention is directed to a solid-state imaging device in which pixels each including a photoelectric conversion portion formed above a semiconductor substrate and an MOS type signal reading circuit formed at the semiconductor substrate and provided for reading out a signal corresponding to electric charges generated in the photoelectric conversion portion are disposed in an array form, wherein: the photoelectric conversion portion includes a pixel electrode, a counter electrode and a photoelectric conversion layer as defined herein; a bias voltage is applied to the counter electrode as defined herein; the signal reading circuit includes a charge storage portion, an output transistor and a reset transistor as defined herein; the charge storage portion includes a first charge storage region, a second charge storage region and a separation/connection region as defined herein; and the output transistor outputs a signal corresponding to the potential of the second charge storage region.