Image Sensor Transfer Transistor Voltage Control
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Solution Overview
Problem
Current image sensors face challenges in optimizing the control of transfer transistors across pixels, leading to suboptimal electrical characteristics such as full well capacity, image lag, backflow, and leakage, particularly due to variations in process and layout structures.
Innovation Solution
The implementation of a configuration where transfer transistor lines receive voltages of different magnitudes, optimized for each pixel or photodiode, to improve the operational efficiency of transfer transistors, including the use of a connection controller to supply varying voltages to transfer transistor lines, thereby addressing the variability in pixel and photodiode characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a shared pixel structure is used to increase photodiode area, then image sensor sensitivity is improved, but transfer transistor control precision deteriorates
Solution Approach 1:
The patent applies local quality by providing different voltage magnitudes to different transfer transistor lines. Specifically, first transfer transistor lines receive a first voltage magnitude while second transfer transistor lines receive a second voltage magnitude, allowing optimization of transfer characteristics for different pixel groups within the shared pixel structure.
Solution Approach 2:
The patent changes the voltage parameter applied to transfer transistors by configuring multiple transfer transistor lines with different voltage magnitudes. This parameter variation enables compensation for process variations and layout differences, improving transfer transistor control precision while maintaining the shared pixel structure.
2Device complexity
If transfer transistor lines receive uniform voltages, then circuit simplicity is maintained, but electrical characteristics such as full well capacity and image lag are suboptimal
Solution Approach 1:
The patent implements local quality by differentiating voltage magnitudes across different transfer transistor lines. First transfer transistor lines are configured to receive a first voltage magnitude while second transfer transistor lines receive a second voltage magnitude, enabling optimized control for different pixel groups and improving electrical characteristics like full well capacity and image lag performance.
3Productivity
If pixel sizes are decreased to increase array density, then image sensor resolution is improved, but photodiode area and transfer transistor control precision deteriorate
Solution Approach 1:
The patent applies parameter changes by configuring different voltage magnitudes for different transfer transistor lines. This allows compensation for the reduced control precision inherent in smaller pixel sizes, maintaining reliable transfer transistor operation despite decreased pixel dimensions and increased array density.
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 approach enhances the electrical characteristics of image sensors by optimizing transfer transistor operations, improving full well capacity, reducing image lag and backflow, and increasing wafer yield.
Implementation Method 1
Each pixel of the plurality of pixels may include a photodiode and a transfer transistor, respectively. The transfer transistor may be configured to transfer charges accumulated in the photodiode to a floating diffusion region.
Data Source
AI summary
An image sensor may optimize control of each pixel and/or each photodiode therein according to various pixel structures therein. An electronic apparatus may include the image sensor. The image sensor may include a plurality of pixels, each including a photodiode and a transfer transistor configured to transfer charges accumulated in the photodiode to a floating diffusion floating diffusion region, and transfer transistor lines respectively connected to gate electrodes of the transfer transistors of the pixels. The transfer transistor lines may receive voltages having different magnitudes.