FinFET Gate Dielectric Hydrogen Profiling for Threshold Voltage Stability
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Solution Overview
Problem
As semiconductor devices, particularly FinFETs, scale down, challenges arise in maintaining performance due to increased interface defects and threshold voltage shifts caused by hydrogen introduction during high-pressure anneal processes, which affect carrier mobility and reliability.
Innovation Solution
A method involving a high-pressure anneal process to introduce hydrogen into the interfacial region of FinFETs, followed by a post-anneal treatment process to maintain hydrogen at the interface while reducing its concentration in the bulk gate dielectric layer, thereby improving carrier mobility and recovering threshold voltage shifts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-pressure anneal process is used to improve carrier mobility, then carrier mobility is improved, but threshold voltage shifts occur
Solution Approach 1:
The patent divides the dielectric layer into two distinct regions: a first dielectric layer in contact with the channel region and a second dielectric layer on top. This segmentation allows differential hydrogen distribution where the first layer maintains higher hydrogen concentration for mobility improvement while the second layer has reduced hydrogen to prevent threshold voltage shifts.
Solution Approach 2:
The patent applies local quality by creating different hydrogen concentration profiles in different regions of the dielectric structure. The first dielectric layer near the channel interface maintains high hydrogen concentration locally to improve carrier mobility, while the second dielectric layer has lower hydrogen concentration to stabilize threshold voltage.
2Reliability
If hydrogen is introduced into the gate dielectric layer to improve carrier mobility, then carrier mobility is improved, but interface defects increase
Solution Approach 1:
The patent creates a localized hydrogen concentration gradient where the first dielectric layer near the channel interface has optimized hydrogen content to improve mobility without creating excessive defects, while the second dielectric layer has reduced hydrogen content to minimize interface defect formation.
Solution Approach 2:
The patent performs preliminary hydrogen introduction during the high-pressure anneal process before final device operation, allowing hydrogen to occupy beneficial sites that improve mobility while avoiding harmful accumulation that would create interface defects during subsequent processing.
3Manufacturing precision
If hydrogen concentration is increased in the gate dielectric layer to recover threshold voltage shifts, then threshold voltage stability is improved, but carrier mobility decreases
Solution Approach 1:
The patent segments the dielectric layer into two functional regions with different hydrogen concentrations: the first dielectric layer maintains higher hydrogen for mobility while the second dielectric layer has lower hydrogen to stabilize threshold voltage, resolving the trade-off between these two parameters.
Solution Approach 2:
The patent changes the hydrogen concentration parameter differentially across the dielectric layer structure, creating a gradient where hydrogen content varies by location to simultaneously optimize both carrier mobility and threshold voltage stability.
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
The approach enhances carrier mobility and reduces threshold voltage shifts, achieving improved device performance by optimizing hydrogen distribution within the gate dielectric layers.
Implementation Method 1
a high-pressure anneal process to introduce hydrogen into the interfacial region of FinFETs
Implementation Method 2
a post-anneal treatment process to maintain hydrogen at the interface while reducing its concentration in the bulk gate dielectric layer
Data Source
AI summary
Embodiment described herein provide a thermal treatment process following a high-pressure anneal process to keep hydrogen at an interface between a channel region and a gate dielectric layer in a field effect transistor while removing hydrogen from the bulk portion of the gate dielectric layer. The thermal treatment process can reduce the amount of threshold voltage shift caused by a high-pressure anneal. The high-pressure anneal and the thermal treatment process may be performed any time after formation of the gate dielectric layer, thus, causing no disruption to the existing process flow.