Poly/Metal Gate Electrode with Titanium Oxide Diffusion Barrier
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Solution Overview
Problem
Conventional semiconductor devices with metal electrodes, such as titanium nitride or tungsten nitride, face high resistance values due to large interface resistance between polysilicon and metal, which affects the diffusion barrier properties and electron flow.
Innovation Solution
A semiconductor device structure is developed with a polysilicon film, a silicide film, and a metal oxide film, specifically titanium oxide, which serves as a diffusion barrier, reducing interface resistance by maintaining amorphous crystallinity and stabilizing generation energy, thereby forming a poly/metal gate electrode with lower resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal film (titanium nitride or tungsten nitride) is formed as an electrode to ensure diffusion barrier property with polysilicon, then the diffusion barrier property is improved, but the resistance value of the electrode and polysilicon/metal interface resistance becomes large
Solution Approach 1:
An oxide film is introduced as an intermediary layer between the polysilicon film and the metal silicide film. This oxide film serves as a diffusion barrier while simultaneously reducing the interface resistance between polysilicon and metal, resolving the contradiction by mediating the interaction between these two materials.
Solution Approach 2:
The electrode structure uses a composite material approach by combining polysilicon, metal silicide, and oxide film in a multi-layer configuration. This composite structure achieves both the diffusion barrier property and low interface resistance that cannot be obtained with a single material.
2Reliability
If a metal film is used as an electrode, then the diffusion barrier property is ensured, but the specific resistance of the electrode increases
Solution Approach 1:
The oxide film acts as a mediator between the polysilicon and metal silicide, enabling the metal electrode to achieve both diffusion barrier functionality and reduced specific resistance through optimized interface characteristics.
Solution Approach 2:
The invention changes the chemical and physical parameters at the electrode interfaces by introducing the oxide film, which modifies the interface resistance and specific resistance characteristics while maintaining the diffusion barrier property.
3Reliability
If titanium nitride is used as the metal layer, then the diffusion barrier is provided, but grain boundary scattering increases resulting in higher resistance
Solution Approach 1:
The oxide film serves as an intermediary that reduces grain boundary scattering effects at the metal-poly silicon interface, allowing the metal layer to maintain diffusion barrier properties while reducing resistance caused by grain boundary scattering.
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 structure achieves a significant reduction in specific resistance of the tungsten electrode, minimizing grain boundary scattering and ensuring stable diffusion barrier properties, resulting in a lower resistance poly/metal gate electrode compared to conventional titanium nitride-based structures.
Implementation Method 1
an oxide film of the metal formed above the silicide film
Implementation Method 2
a silicide film of a metal formed on the polysilicon film
Data Source
AI summary
According to one embodiment, a semiconductor device includes a polysilicon film formed above a semiconductor substrate, and a silicide film of a metal formed on the polysilicon film. The semiconductor device of the embodiment includes an oxide film of the metal formed above the silicide film, and a film containing tungsten or molybdenum formed on the oxide film.