Offset Gate Projections for Charge Transfer Stability
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Solution Overview
Problem
Conventional solid-state imaging devices experience deteriorated transfer characteristics of electrical charges due to potential dips or barriers formed in the offset gate portion, especially when the offset gate layer is formed over a wide range or when manufacturing errors cause shifts in the relative position of the offset gate electrode, leading to inefficiencies in charge transfer.
Innovation Solution
The implementation of an offset gate portion with a semiconductor substrate-based offset gate layer and electrode, featuring projections adjacent to the second transfer gate portion, which applies a constant voltage and optimizes the electric potential to suppress potential dips and barriers, ensuring effective and speedy charge transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the offset gate layer is formed over a wide range of regions, then the coverage area of the offset gate portion is increased, but a potential dip is formed in the electric potential of the central portion of the offset gate layer which deteriorates transfer characteristics
Solution Approach 1:
The offset gate electrode is positioned to overlap specifically with the peripheral portions of the offset gate layer, creating a localized electric field configuration. This selective positioning ensures that the electric potential is optimized at the edges where charge transfer occurs, while avoiding the formation of potential dips in the central region, thus maintaining both wide coverage and reliable transfer characteristics
Solution Approach 2:
The offset gate electrode acts as an intermediary element that mediates between the wide-area offset gate layer and the charge storage portions. By positioning the electrode to overlap only with peripheral portions, it creates an optimized electric field distribution that prevents potential dips while maintaining the benefits of wide-area charge collection
2Ease of manufacture
If the relative position of the offset gate electrode to the offset gate layer is shifted, then manufacturing flexibility is improved, but a potential dip or potential barrier is formed which deteriorates transfer characteristics
Solution Approach 1:
The offset gate electrode is preliminarily positioned to overlap with the peripheral portions of the offset gate layer before final assembly. This pre-positioning ensures that even if manufacturing variations occur, the critical electric field configuration is already established to prevent potential dips and barriers, maintaining transfer characteristics despite positioning flexibility
Solution Approach 2:
The electrode positioning is optimized to create local electric field enhancement at the peripheral portions where charge transfer is most critical. This localized optimization ensures that transfer characteristics are maintained even when the overall relative position varies during manufacturing
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 enhances the accuracy of signal voltage readout by stabilizing the electric potential between the second transfer gate and charge detecting portions, improving the transfer characteristics and reducing the impact of manufacturing errors on charge transfer efficiency.
Implementation Method 1
a deepest portion of electric potential is formed in a central portion of the offset gate layer... a potential dip is formed in the electric potential of the central portion... a potential dip or a potential barrier is formed in the electric potential between the offset gate portion and a transfer gate portion
Data Source
AI summary
Certain embodiments provide a solid-state imaging device including a pixel portion, a charge storage portion, a first transfer gate portion, a charge detecting portion, a second transfer gate portion, and an offset gate portion. The charge storage portion stores the electrical charges generated in the pixel portion. The first transfer gate portion transfers electrical charges from the pixel portion to the charge storage portion, and the second transfer gate portion transfers the electrical charges from the charge storage portion to the charge detecting portion. The offset gate portion is provided between the second transfer gate portion and the charge detecting portion and is applied with a predetermined constant voltage. This offset gate portion includes an offset gate layer that has a plurality of projections formed at positions adjacent to the second transfer gate portion and an offset gate electrode.