Graphene Gate FinFET for Threshold Voltage Control
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Solution Overview
Problem
The challenge in semiconductor manufacturing is to produce FinFET devices with varying threshold voltages, as current techniques face difficulties in uniformly doping small channel lengths and incorporating work-function adjusting metals, leading to performance variations and complexity in device fabrication.
Innovation Solution
The use of a FinFET device with a gate electrode comprised of graphene, where a fin is formed in a semiconducting substrate, a layer of gate insulation material is applied, and a graphene gate electrode is positioned around the fin, with an insulating material on top, allowing for the adjustment of the gate electrode's height and work function to control threshold voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If ion implantation is used to dope channel regions to produce different threshold voltages, then threshold voltage variation can be controlled, but manufacturing precision deteriorates due to inherent variations in the ion implanting process at very small channel lengths (10 nm or less)
Solution Approach 1:
The patent extracts the doping step entirely from the device fabrication process. Instead of using ion implantation to dope channel regions, the invention uses undoped semiconductor material for the channel and achieves threshold voltage control through work function adjustment of the gate electrode only. This eliminates the manufacturing precision problems associated with ion implantation at 10 nm scale while retaining the ability to produce devices with different threshold voltages.
Solution Approach 2:
The patent changes the parameter being adjusted for threshold voltage control from channel doping concentration to gate electrode work function. By modifying the gate electrode material composition or structure to achieve different work functions, the invention can control threshold voltage without relying on precise ion implantation doping, thus avoiding the manufacturing precision deterioration that occurs at very small channel lengths.
2Adaptability or versatility
If work-function adjusting metals are incorporated into gate structures to produce different threshold voltages, then threshold voltage adaptability is improved, but device complexity increases due to the additional materials and fabrication steps required
Solution Approach 1:
The patent makes the gate electrode structure universal by using the same basic structure for all devices regardless of threshold voltage requirements. The gate electrode serves multiple functions: it provides the necessary electrical control and its work function can be adjusted through material selection or structure modification to achieve different threshold voltages. This multi-functionality eliminates the need for additional work-function adjusting metal layers or complex gate structures, thereby reducing device complexity while maintaining threshold voltage adaptability.
3Productivity
If channel length is decreased to improve switching speed and increase device density, then operating speed and productivity are improved, but short channel effects worsen due to reduced separation between source and drain regions
Solution Approach 1:
The patent changes the control mechanism for threshold voltage from channel doping to gate work function adjustment. This parameter change allows for better control of short channel effects because the gate electrode can more effectively control the channel potential when the channel is undoped or lightly doped. The undoped channel reduces junction leakage and improves gate control, thereby maintaining reliability even as channel length decreases to increase device 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 enables the production of FinFET devices with controlled threshold voltages, reducing performance variations and simplifying the fabrication process by utilizing graphene's conductive properties and flexibility in gate electrode formation.
Implementation Method 1
a gate electrode comprised of graphene positioned on the layer of gate insulation material around at least a portion of the fin
Data Source
AI summary
One illustrative device disclosed herein includes at least one fin comprised of a semiconducting material, a layer of gate insulation material positioned adjacent an outer surface of the fin, a gate electrode comprised of graphene positioned on the layer of gate insulation material around at least a portion of the fin, and an insulating material formed on the gate electrode.