Improved Gate Structures for Reliable Transistor Performance
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Summary
Problems
As semiconductor devices continue to shrink in feature size, challenges arise in maintaining device performance due to issues with gate dielectric and work function metal layer retention, leading to instability in flatband voltage and threshold voltage, which affects integration density and overall device efficiency.
Innovation solutions
The implementation of an aluminum treatment followed by a fluorine treatment on gate dielectrics and work function metal layers, respectively, to improve fluorine retention and diffusion, resulting in enhanced gate stack performance by increasing flatband voltage towards the band edge of the metal and decreasing threshold voltage.
TRIZ Analysis
Specific contradictions:
General conflict description:
Principle concept:
If fluorine treatment is applied to work function metal layer, then flatband voltage is increased towards band edge, but fluorine dissociates from work function metal layer
Why choose this principle:
An aluminum layer is introduced as an intermediary between the gate dielectric and the work function metal layer. The aluminum layer serves as a mediator that attracts and retains fluorine atoms, preventing fluorine dissociation from the work function metal layer while still enabling the desired flatband voltage adjustment. The aluminum layer acts as a fluorine reservoir that maintains fluorine concentration in the gate stack.
Principle concept:
If fluorine treatment is applied to work function metal layer, then flatband voltage is increased towards band edge, but fluorine dissociates from work function metal layer
Why choose this principle:
The aluminum layer is deposited on the gate dielectric before the work function metal layer is applied. This preliminary placement of aluminum creates a structure that is pre-configured to retain fluorine during subsequent fluorine treatment processes, preventing the harmful dissociation effect from occurring in the first place.
Application Domain
Data Source
AI summary:
The implementation of an aluminum treatment followed by a fluorine treatment on gate dielectrics and work function metal layers, respectively, to improve fluorine retention and diffusion, resulting in enhanced gate stack performance by increasing flatband voltage towards the band edge of the metal and decreasing threshold voltage.
Abstract
In some embodiments, a method includes forming a plurality of nanostructures over a substrate; etching the plurality of nanostructures to form first recesses; forming source/drain regions in the first recesses; removing first nanostructures of the plurality of nanostructures leaving second nanostructures of the plurality of nanostructures; depositing a gate dielectric over and around the second nanostructures; performing an aluminum treatment on the gate dielectric; depositing a first conductive material over and around the gate dielectric; performing a fluorine treatment on the first conductive material; and depositing a second conductive material over and around the first conductive material.