Gate Contact Layer Stack for Uniform Resistance and Fewer Defects
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Solution Overview
Problem
Semiconductor devices face challenges in achieving improved quality, yield, performance, and reliability due to issues related to resistance uniformity during the scaling-down process, particularly in the formation of conductive layers.
Innovation Solution
A conductive layer stack is designed with an intervening layer of tungsten silicide and a filler layer of tungsten, both positioned on a titanium nitride under-layer with a columnar grain structure, where the intervening layer's thickness is greater than 4.1 nm, and the filler layer is deposited using germanium-containing reducing agents to promote alpha-tungsten growth, reducing defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the intervening layer thickness is increased to improve resistance uniformity, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent applies parameter changes by specifying a minimum thickness of 4.1 nm for the tungsten silicide intervening layer. This quantitative parameter change ensures sufficient material volume to maintain uniform resistance characteristics during device operation, directly addressing the reliability improvement while keeping the structural complexity manageable through a defined threshold rather than continuous optimization.
Solution Approach 2:
The patent employs composite materials by creating a multi-layer structure consisting of titanium nitride under-layer, tungsten silicide intervening layer, and tungsten filler layer. This composite approach combines materials with complementary properties: titanium nitride provides structural stability, tungsten silicide provides controlled conductivity and uniformity, and tungsten provides low resistance, collectively solving the resistance uniformity issue while managing overall device complexity.
2Manufacturing precision
If the intervening layer thickness is increased to reduce resistance uniformity issues, then manufacturing precision is improved, but loss of substance increases
Solution Approach 1:
The patent establishes a specific thickness parameter of greater than 4.1 nm for the tungsten silicide intervening layer. This precise parameter definition optimizes the balance between achieving sufficient resistance uniformity (manufacturing precision) and minimizing excessive material consumption, providing a clear fabrication target that prevents both under-deposition and over-deposition waste.
Solution Approach 2:
The patent applies local quality by making the intervening layer thickness specifically greater than 4.1 nm only where needed for resistance uniformity control, rather than uniformly increasing thickness throughout the entire device structure. This localized approach ensures manufacturing precision is improved where critical while minimizing unnecessary material consumption in non-critical regions.
3Reliability
If germanium-containing reducing agents are used to promote alpha-tungsten growth, then reliability is improved by reducing defects, but manufacturing complexity increases
Solution Approach 1:
The patent changes the chemical composition parameter of the reducing agent by specifying germanium-containing compounds. This parameter change promotes the formation of alpha-tungsten phase with fewer defects, improving reliability. The specific chemical composition adjustment provides a straightforward process modification that achieves defect reduction without requiring complex process equipment or multiple deposition steps.
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 design enhances the reliability, yield, and performance of semiconductor devices by improving resistance uniformity and reducing defects, leading to better overall device performance.
Implementation Method 1
the filler layer deposited using germanium-containing reducing agents may reduce resistance, thin filler nucleation layer that yield alpha-tungsten growth
Data Source
AI summary
The present application discloses a conductive layer stack, a semiconductor device and methods for fabricating the conductive layer stack and the semiconductor device. The conductive layer stack includes an intervening layer comprising tungsten silicide and positioned on an under-layer; a filler layer comprising tungsten and positioned on the intervening layer. The under-layer comprises titanium nitride and comprises a columnar grain structure. A thickness of the intervening layer is greater than about 4.1 nm.