Gate Electrode Barrier Patterns for Threshold Voltage Control
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Solution Overview
Problem
As semiconductor devices are scaled down, the operating characteristics of MOSFETs deteriorate, leading to challenges in achieving superior performance and integration, particularly in maintaining effective work functions and preventing material diffusion that affects transistor threshold voltages.
Innovation Solution
The semiconductor device incorporates a gate electrode structure with a p-type work function metal, an n-type work function metal, an amorphous tungsten carbon nitride barrier layer, and a thicker p-type work function metal barrier layer to control threshold voltages and prevent material diffusion, including the use of a ferroelectric gate dielectric material for negative capacitance effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If MOSFETs are scaled down to improve integration density, then device size is reduced, but operating characteristics deteriorate
Solution Approach 1:
The gate electrode structure employs different materials with specific work functions at different locations: p-type work function metal (titanium nitride) at the source end, n-type work function metal (tantalum nitride) at the drain end, and tungsten carbon nitride barrier layers throughout. This local differentiation of material properties enables precise control of threshold voltages in scaled-down devices while maintaining reliable operation.
Solution Approach 2:
The gate electrode is constructed as a composite structure combining multiple materials: titanium nitride (p-type work function metal), tantalum nitride (n-type work function metal), and tungsten carbon nitride (barrier layer). This composite approach allows simultaneous optimization of work function characteristics and diffusion barrier properties in miniaturized MOSFETs.
2Reliability
If material diffusion is prevented to maintain threshold voltages, then device performance is improved, but device complexity increases
Solution Approach 1:
Tungsten carbon nitride barrier layers are introduced as intermediary structures between the work function metals and the channel. These barrier layers specifically prevent fluorine diffusion from aluminum oxide layers into the work function metals, thereby stabilizing threshold voltages without requiring complex additional structures.
Solution Approach 2:
The gate electrode is segmented into multiple functional layers: p-type work function metal layer, n-type work function metal layer, and tungsten carbon nitride barrier layers. This segmentation allows each layer to perform its specific function (work function adjustment, diffusion barrier) independently, simplifying the overall design compared to using a single complex material.
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 configuration enhances electrical characteristics, such as sub-threshold swing and reduces operating voltage, while preventing fluorine diffusion and maintaining desired threshold voltages by inhibiting material diffusion through the amorphous barrier layer.
Implementation Method 1
a first barrier pattern on the second metal pattern, the first barrier pattern including an amorphous metal layer that includes tungsten (W), carbon (C), and nitrogen (N)
Implementation Method 2
including the use of a ferroelectric gate dielectric material for negative capacitance effects
Data Source
AI summary
Semiconductor devices are provided. A semiconductor device includes a first active pattern on a first region of a substrate, a pair of first source/drain patterns on the first active pattern, a first channel pattern between the pair of first source/drain patterns, and a gate electrode that extends across the first channel pattern. The gate electrode is on an uppermost surface and at least one sidewall of the first channel pattern. The gate electrode includes a first metal pattern including a p-type work function metal, a second metal pattern on the first metal pattern and including an n-type work function metal, a first barrier pattern on the second metal pattern and including an amorphous metal layer that includes tungsten (W), carbon (C), and nitrogen (N), and a second barrier pattern on the first barrier pattern. The second barrier pattern includes the p-type work function metal.