Gate Electrode Thickness Tuning for Multi-Threshold Transistors
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Solution Overview
Problem
Traditional methods of modulating transistor threshold voltage by doping affect switching speed and increase performance variation due to dopant scattering and random fluctuations, limiting the optimization of power dissipation and clock frequency in integrated circuits.
Innovation Solution
The use of varying thicknesses of gate electrode material to modulate threshold voltages without doping, allowing for multiple threshold voltage devices with improved switching speed and reduced performance variation by altering the workfunction of the gate instead of the Fermi level of the channel body.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If doping is used to modulate threshold voltage, then threshold voltage can be adjusted, but switching speed decreases and performance variation increases
Solution Approach 1:
The patent changes the physical parameter used to modulate threshold voltage from dopant concentration to gate electrode thickness. By varying the thickness of the gate electrode (e.g., from 5nm to 20nm), different threshold voltages are achieved without introducing dopants that would scatter carriers and reduce switching speed. This parameter change eliminates the trade-off between threshold voltage control and switching performance.
Solution Approach 2:
The patent substitutes the chemical doping mechanism with a physical/structural mechanism. Instead of using chemical impurities (dopants) to alter the Fermi level and modulate threshold voltage, the invention uses the physical thickness of the gate electrode to modify the workfunction and control threshold voltage. This substitution eliminates the harmful scattering effects of dopant atoms while maintaining threshold voltage modularity.
2Reliability
If doping is used to modulate threshold voltage, then threshold voltage can be adjusted, but carrier mobility decreases due to dopant scattering
Solution Approach 1:
The patent changes the control parameter from dopant concentration to gate electrode thickness. By adjusting the thickness parameter of the gate electrode, precise threshold voltage control is achieved without introducing dopant atoms that would scatter charge carriers and reduce mobility. The relationship between gate thickness and threshold voltage provides a clean, scatter-free modulation mechanism.
Solution Approach 2:
The patent replaces the chemical doping mechanism with a structural/physical mechanism. Instead of relying on dopant atoms to shift the Fermi level and control threshold voltage, the invention uses the physical dimension (thickness) of the gate electrode to modify the workfunction. This substitution preserves carrier mobility by eliminating dopant-induced scattering while maintaining effective threshold voltage control.
3Loss of energy
If higher dopant levels are used to increase threshold voltage, then power consumption decreases, but performance variation increases due to random dopant fluctuations
Solution Approach 1:
The patent changes from controlling threshold voltage via dopant concentration to controlling it via gate electrode thickness. This parameter change eliminates random dopant fluctuations that cause threshold voltage variation. The thickness parameter can be controlled with atomic-layer precision during deposition, ensuring uniform threshold voltage across all transistors while maintaining the ability to optimize power dissipation through threshold voltage selection.
Solution Approach 2:
The patent substitutes the statistical/chemical doping process with a deterministic physical process. Instead of relying on probabilistic dopant distribution that leads to random fluctuations and performance variation, the invention uses controlled deposition of gate electrode material where thickness can be precisely and uniformly controlled. This substitution eliminates the manufacturing precision issues associated with doping while maintaining power dissipation optimization capabilities.
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 transistors with greater switching speed and carrier mobility for a given leakage level, reducing transistor performance variation and optimizing power dissipation and clock frequency in integrated circuits.
Implementation Method 1
modulating a threshold voltage of the transistor device may include depositing a gate electrode material in a gate electrode region corresponding to the transistor device, wherein the gate electrode material has a thickness that modulates a workfunction of the gate electrode
Data Source
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AI summary
Embodiments of the present disclosure describe multi-threshold voltage devices and associated techniques and configurations. In one embodiment, an apparatus includes a semiconductor substrate, a channel body disposed on the semiconductor substrate, a first gate electrode having a first thickness coupled with the channel body and a second gate electrode having a second thickness coupled with the channel body, wherein the first thickness is greater than the second thickness. Other embodiments may be described and/or claimed.