Gate Terminal Surface Oxidation for Work Function Tuning
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In advanced semiconductor manufacturing, particularly for FinFET and gate-all-around (GAA) structures, the correlation between gate material thickness and work function breaks down, making it difficult to tune threshold voltages without increasing gate stack thickness and incurring leakage penalties.
Innovation Solution
A plasma oxidation treatment is applied to the surface of a metallic nitride layer in the gate stack to enhance the work function, allowing for precise tuning of threshold voltages without increasing thickness, using a controlled radical-rich plasma process to limit oxidation to a few monolayers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If gate material thickness is increased to tune threshold voltage, then work function is improved, but dielectric thickness increases causing leakage penalties
Solution Approach 1:
The patent applies a plasma oxidation treatment specifically to the outer surface of the metallic nitride layer, creating a localized oxidation layer only where needed. This local modification enhances the work function by 50-80 mV without requiring increase in overall gate stack thickness, thereby resolving the contradiction between threshold voltage tuning and gate stack thickness control
Solution Approach 2:
The patent changes the chemical composition parameter of the gate terminal surface by introducing an oxidation layer with at least 50% metallic dioxide through plasma treatment. This parameter change (surface composition) achieves work function enhancement without changing the physical dimension parameter (thickness), thus resolving the technical contradiction
2Manufacturing precision
If plasma oxidation is applied to enhance work function, then threshold voltage tuning is improved, but oxidation layer thickness must be controlled to avoid leakage
Solution Approach 1:
The patent applies plasma oxidation treatment in a controlled manner to achieve partial oxidation, creating an oxidation layer comprising at least 50% metallic dioxide. This partial oxidation approach provides sufficient work function enhancement (50-80 mV) while avoiding excessive oxidation that would create thick dielectric layers and cause leakage penalties
Solution Approach 2:
The patent replaces traditional mechanical/thick-film approaches to work function tuning with a chemical/plasma-based surface treatment. The plasma oxidation process uses radical-rich plasma chemistry to modify the surface properties of the metallic nitride layer, achieving work function enhancement through chemical composition change rather than physical thickness increase
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 method effectively boosts the work function by 50 mV to 80 mV, improving transistor performance without affecting dielectric thickness or process flow, and is suitable for high-volume manufacturing.
Implementation Method 1
a plasma oxidation treatment after a metallic nitride (e.g., MoN film) has been deposited
Implementation Method 2
using a controlled radical-rich plasma process to limit oxidation to a few monolayers
Data Source
AI summary
In some embodiments, the strength of the work function (WF) for P-type MOS transistors may be boosted by doping a gate layer surface using a plasma oxidation treatment after a metallic nitride (e.g., MoN film) has been deposited.