Gate Work Function Tuning Layers for N-Type Threshold Voltage
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Solution Overview
Problem
As the minimum feature sizes in semiconductor devices are reduced, challenges arise in achieving optimal integration density and improving threshold voltages of n-type devices.
Innovation Solution
The use of work function tuning layers, specifically comprising Zr, Hf, Nb, Ta, or combinations thereof, in gate electrodes to lower the work function value and shift the effective work function to n-type, thereby improving threshold voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If minimum feature sizes are reduced to improve integration density, then more components can be integrated into a given area, but achieving optimal threshold voltages in n-type devices becomes more difficult
Solution Approach 1:
The patent changes the work function parameter of the gate electrode by incorporating metal nitride layers (such as titanium nitride, tantalum nitride, or tungsten nitride) with specific work function values. This parameter adjustment allows the gate electrode to provide appropriate threshold voltages for n-type devices even as feature sizes are reduced and integration density increases.
Solution Approach 2:
The gate electrode is constructed as a composite structure combining multiple materials with different properties. Specifically, it includes metal nitride layers (providing work function control) integrated with other conductive materials. This composite approach enables simultaneous optimization of both threshold voltage control and compatibility with scaled device geometries.
2Reliability
If conventional gate electrode materials are used, then manufacturing process is simpler, but threshold voltage control in n-type devices is insufficient
Solution Approach 1:
The patent modifies the work function parameter of the gate electrode by selecting metal nitride materials with specific work function values (typically in the range of 4.0-4.8 eV). This parameter change enables better threshold voltage control for n-type devices without requiring complex multi-layer structures, thus balancing performance improvement with manufacturing simplicity.
Solution Approach 2:
The patent employs metal nitride layers that can be deposited using standard sputtering or chemical vapor deposition techniques. These materials provide the necessary work function adjustment in a single或少量 layers, avoiding the need for complex multi-layer stacks or expensive specialized materials, thereby maintaining manufacturing efficiency while improving device performance.
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 enhances the threshold voltages of n-type devices, improving their performance and integration density in semiconductor devices.
Implementation Method 1
work function tuning layers, specifically comprising Zr, Hf, Nb, Ta, or combinations thereof, in gate electrodes to lower the work function value and shift the effective work function to n-type
Data Source
AI summary
An embodiment includes a device having nanostructures on a substrate, the nanostructures including a channel region. The device also includes a gate dielectric layer wrapping around each of the nanostructures. The device also includes a first work function tuning layer on the gate dielectric layer, the first work function tuning layer including a first n-type work function metal, aluminum, and carbon, the first n-type work function metal having a work function value less than titanium. The device also includes a glue layer on the first work function tuning layer. The device also includes and a fill layer on the glue layer.