Solid-state imaging device ring-shaped charge accumulation layer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In solid-state imaging devices, the wide charge accumulation layer leads to a deep potential well near its center, causing charges to accumulate far from the transfer gate, resulting in a small voltage margin for charge transfer and making it difficult to read charges at low voltages.
Innovation Solution
The implementation of a ring-shaped second charge accumulation layer, which shifts the deepest potential closer to the transfer gate, allowing for a lower voltage application and improved charge transfer efficiency without deteriorating residual image characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a wide charge accumulation layer is used, then the charge accumulation capacity is improved, but the voltage margin for charge transfer deteriorates
Solution Approach 1:
The charge accumulation layer is divided into a first charge accumulation layer (wide area) and a second charge accumulation layer (ring-shaped), where each layer serves a specific function: the first layer provides charge accumulation capacity while the second layer controls potential distribution to improve charge transfer
Solution Approach 2:
Different regions of the charge accumulation structure are given different properties: the first charge accumulation layer has a wide area for high charge capacity, while the second charge accumulation layer has a ring shape with specific impurity concentration to control the potential well depth and position, creating optimal local conditions for charge transfer
2Quantity of substance
If a wide charge accumulation layer is used, then the charge accumulation capacity is improved, but the charge transfer efficiency at low voltage deteriorates
Solution Approach 1:
The charge accumulation layer is segmented into two functional layers: the first layer (wide area) accumulates charge while the second layer (ring-shaped) facilitates efficient charge transfer to the transfer gate by controlling the potential distribution
Solution Approach 2:
The impurity concentration in the second charge accumulation layer is optimized to create an appropriate potential well depth, and the ring-shaped geometry is designed with specific dimensions to ensure that charges can be efficiently transferred to the transfer gate at low voltages while maintaining high charge accumulation capacity
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 enables efficient charge transfer and maintains linearity of light intensity measurement even at low luminance levels, enhancing the voltage margin and image quality by positioning the deepest potential close to the transfer gate, thus overcoming the limitations of traditional solid-state imaging devices.
Implementation Method 1
a first light receiving layer which is provided in a planar shape on the surface of the semiconductor substrate and which produces charge according to a received light amount of incident light
Data Source
AI summary
Certain embodiments provide a solid-state imaging device including a pixel portion including a first light receiving layer, a charge accumulation portion including a first charge accumulation layer which accumulates a charge, a first transfer gate portion, a charge detection portion and a second transfer gate portion. The first transfer gate portion transfers the charge from the pixel portion to the charge accumulation portion, and the second transfer gate portion transfers the charge from the charge accumulation portion to the charge detection portion. The charge detection portion causes a voltage drop corresponding to an amount of the charge transferred to this region. An impurity layer of a ring shape which includes an opening portion is provided on a surface of at least one of the first light reception layer of the pixel portion and the first charge accumulation layer of the charge accumulation portion.