Transistor Gate Structure With Tungsten pMOS Work Function Layer
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Solution Overview
Problem
As semiconductor devices continue to shrink in feature size, challenges arise in maintaining device performance and reducing resistance, particularly in p-type devices, where existing work function tuning layers with metals like tantalum do not offer optimal results.
Innovation Solution
The use of tungsten-containing work function materials, such as pure tungsten, tungsten nitride, or tungsten carbide, is introduced to form work function tuning layers in p-type devices, which are deposited using atomic layer deposition (ALD) to achieve lower resistance and improved device performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If feature size is reduced to increase integration density, then more components can be integrated into a given area, but resistance increases and device performance deteriorates
Solution Approach 1:
The patent changes the material parameter of the work function tuning layer from traditional metals (tantalum, titanium nitride) to tungsten-containing materials. This material substitution alters the electrical properties, specifically reducing resistance in p-type devices while maintaining the required work function characteristics, thereby preserving device performance despite feature size reduction
Solution Approach 2:
The patent employs composite gate structures consisting of multiple layers including gate dielectric, work function tuning layer, and fill material. The work function tuning layer itself may be composite (e.g., tungsten nitride, tungsten carbide, or tungsten carbonitride). This multi-layer composite approach allows optimization of both work function and resistance properties simultaneously
2Ease of manufacture
If traditional work function tuning materials (tantalum, titanium nitride) are used, then device fabrication is straightforward, but resistance is too high for optimal p-type device performance
Solution Approach 1:
The patent changes the material composition parameter by substituting tungsten-containing materials for traditional work function tuning materials. Tungsten and its compounds (tungsten nitride, tungsten carbide, tungsten carbonitride) provide both the necessary work function characteristics and lower resistance, achieving optimal p-type device performance while maintaining compatibility with existing ALD fabrication processes
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 tungsten-containing work function tuning layers in p-type devices demonstrate lower resistance and enhanced performance compared to layers made with other metals, effectively addressing the challenges of shrinking feature sizes and resistance issues.
Implementation Method 1
which are deposited using atomic layer deposition (ALD)
Data Source
AI summary
In an embodiment, a device includes: a p-type transistor including: a first channel region; a first gate dielectric layer on the first channel region; a tungsten-containing work function tuning layer on the first gate dielectric layer; and a first fill layer on the tungsten-containing work function tuning layer; and an n-type transistor including: a second channel region; a second gate dielectric layer on the second channel region; a tungsten-free work function tuning layer on the second gate dielectric layer; and a second fill layer on the tungsten-free work function tuning layer.