Transistor Threshold Voltage Control via Interface Layer
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Solution Overview
Problem
Conventional oxide transistors with oxide channel layers face challenges in controlling threshold voltage due to self-compensation, making it difficult to fabricate n-channel and p-channel metal-oxide semiconductor transistors with adjustable threshold voltages.
Innovation Solution
Incorporating a threshold voltage adjusting layer with a work function different from the channel layer, which can be a metal or doped semiconductor, to control the threshold voltage by altering the energy bands and allowing for the formation of both enhancement and depletion mode transistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If doping is used to control threshold voltage in oxide transistors, then threshold voltage control is attempted, but self-compensation occurs making control difficult
Solution Approach 1:
An interface layer is introduced between the oxide channel layer and the gate electrode to mediate the interaction. This interface layer serves as an intermediary that enables threshold voltage control through its work function properties without causing self-compensation issues in the oxide channel layer itself.
Solution Approach 2:
The threshold voltage is controlled by changing the work function parameter of the interface layer rather than doping the oxide channel layer. This parameter change approach allows for reliable threshold voltage control without triggering self-compensation mechanisms.
2Reliability
If oxide material is used for channel layer, then high carrier mobility is achieved, but threshold voltage control becomes difficult
Solution Approach 1:
The gate structure is segmented into multiple functional layers: the oxide channel layer for high carrier mobility and the separate interface layer for threshold voltage control. This segmentation allows each layer to optimize its specific function without interfering with the other.
Solution Approach 2:
The interface layer acts as a mediator between the oxide channel layer and the gate electrode, enabling threshold voltage control while preserving the high carrier mobility properties of the oxide material.
3Ease of manufacture
If conventional oxide transistor structure is used, then fabrication is simplified, but both enhancement and depletion mode transistors cannot be easily fabricated
Solution Approach 1:
The interface layer provides a universal mechanism for threshold voltage control that works for both enhancement mode and depletion mode transistors. By adjusting the interface layer's work function, either mode can be achieved using the same basic fabrication process.
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 enables precise adjustment of threshold voltage, allowing for the fabrication of transistors with distinct threshold voltages, enhancing operational flexibility and reducing the need for doping processes, thereby improving transistor performance and manufacturing efficiency.
Implementation Method 1
The first threshold voltage adjusting layer may have a work function that is different from a work function of the first channel layer
Data Source
AI summary
A transistor, a semiconductor device including the transistor and methods of manufacturing the same are provided, the transistor including a threshold voltage adjusting layer contacting a channel layer. A source electrode and a drain electrode contacting may be formed opposing ends of the channel layer. A gate electrode separated from the channel layer may be formed. A gate insulating layer may be formed between the channel layer and the gate electrode.