Source Follower Transistor with Segmented Semiconductor Layers
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Solution Overview
Problem
Image sensors face challenges in reducing voltage errors and power consumption in source follower transistors, which affect the accuracy of light intensity signals and overall power efficiency.
Innovation Solution
The design includes a source follower transistor with a gate voltage dependent on charges accumulated in a photo detecting device, featuring a gate insulating layer, first and second conductive type semiconductor layers, and a blocking structure like shallow trench isolation to manage carrier movement and reduce power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional source follower transistor is used, then the device can operate with simple structure, but voltage errors in output signals increase and measurement precision deteriorates
Solution Approach 1:
The semiconductor layer is divided into a first semiconductor layer and a second semiconductor layer with different conductive types. This segmentation creates distinct functional regions that reduce voltage errors in the source follower output while maintaining overall structural manageability through clear layer separation.
Solution Approach 2:
Different regions of the transistor are given different conductive types (first conductive type in the first semiconductor layer, second conductive type in the second semiconductor layer). This local differentiation of electrical properties allows specific regions to optimize for voltage error reduction while the overall structure remains relatively simple.
2Use of energy by stationary object
If a conventional source follower transistor is used, then the device can maintain simple configuration, but power consumption increases
Solution Approach 1:
The transistor configuration is segmented into multiple semiconductor layers with different conductive types, allowing power management optimization in each layer independently. This reduces overall power consumption while keeping the configuration organized and manageable.
Solution Approach 2:
The conductive type parameter is changed across different semiconductor layers (from first conductive type to second conductive type), enabling optimization of power consumption characteristics without requiring complete redesign of the overall transistor configuration.
3Measurement precision
If the semiconductor layer has uniform conductive type, then the structure can be simple, but carrier movement control becomes insufficient leading to increased voltage errors
Solution Approach 1:
The semiconductor layer structure implements local quality differentiation by having the first semiconductor layer with first conductive type and the second semiconductor layer with second conductive type. This allows precise control of carrier movement in different regions, reducing voltage errors while maintaining reasonable structural complexity.
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 reduces voltage errors and power consumption, enhancing the accuracy of light intensity signals and improving the overall efficiency of image sensors.
Implementation Method 1
The photo detecting device may generate electric signals according to the intensity of absorbed light. For example, a photo diode may absorb light and thus generate a current.
Implementation Method 2
a gate insulating layer formed under the gate
Implementation Method 3
The source follower transistor may further include a blocking structure that blocks the carriers from moving between the source and the second semiconductor layer.
Data Source
AI summary
Provided is an image sensor including a source follower transistor. The source follower transistor may include a channel structure that is provided between a source and a drain, and includes a first semiconductor layer, a second semiconductor layer, and a blocking structure. The first semiconductor layer may be spaced apart from a gate insulating layer of the source follower transistor by a first depth or more. Carriers may move from the source of the source follower transistor to the drain thereof through the first semiconductor layer.