Work Function Metal Layer Pre-Treatment for Semiconductor Gate Electrodes
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Solution Overview
Problem
Existing semiconductor manufacturing processes face challenges in achieving precise work function tuning for metal gate electrodes, leading to limited device performance due to inadequate tuning knobs and poor metal layer deposition, which results in gaps or voids in the metal layer.
Innovation Solution
A pre-deposition treatment using chlorine or fluorine-based metal precursors is applied to clean and reduce the thickness of the work-function metal layer before subsequent atomic layer deposition, ensuring a clean, void-free metal gate layer and enhancing work function tuning capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional work function tuning approaches are used (adjusting metal layer thickness), then work function can be partially tuned, but the tuning range is limited and metal loading effects cannot be adequately overcome
Solution Approach 1:
The patent applies parameter changes by modifying the chemical composition and thickness of the metal layer to achieve work function tuning. Specifically, it uses a titanium nitride (TiN) layer with controlled thickness (5-20 nm) and composition to achieve the desired work function values, overcoming the limitations of traditional thickness-adjustment methods alone
Solution Approach 2:
The patent employs composite materials by combining titanium nitride (TiN) with other metals or metal compounds to create a multi-component metal gate electrode structure. This composite approach enables broader work function tuning range and better control over metal loading effects compared to single-metal layers
2Object-generated harmful factors
If thicker metal layers are used to overcome work function metal loading effects, then loading effects may be reduced, but device dimensions increase and scaling is compromised
Solution Approach 1:
The patent changes the material parameters by using titanium nitride (TiN) with specific stoichiometry and controlled thickness (5-20 nm). This material selection and thickness optimization reduce metal loading effects while maintaining thin layer dimensions, enabling continued device scaling
Solution Approach 2:
The patent applies local quality by creating a graded or non-uniform metal gate structure where the composition or thickness varies locally to optimize performance. The TiN layer is specifically engineered with controlled thickness distribution to minimize loading effects in critical regions while maintaining overall device scaling
3Ease of manufacture
If conventional metal layer deposition is used, then deposition process is simple, but gaps or voids form in the metal layer deteriorating device performance
Solution Approach 1:
The patent applies preliminary action by performing surface preparation and treatment of the substrate before depositing the metal gate electrode. This includes cleaning and conditioning the surface to ensure optimal adhesion and continuous film formation, preventing gaps and voids while maintaining process simplicity
Solution Approach 2:
The patent optimizes deposition parameters such as deposition temperature, pressure, and rate to achieve continuous, gap-free metal layers. By carefully controlling these parameters during TiN and other metal layer deposition, the process maintains simplicity while ensuring high reliability and uniform film coverage
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 improves the threshold voltage and reliability of semiconductor devices by providing a more precise work function setting, reducing metal surface loading effects and mitigating gap fill issues, resulting in improved device performance.
Implementation Method 1
A pre-deposition treatment using chlorine or fluorine-based metal precursors is applied to clean and reduce the thickness of the work-function metal layer
Implementation Method 2
subsequent atomic layer deposition
Data Source
AI summary
A method and structure for providing a pre-deposition treatment (e.g., of a work-function layer) to accomplish work function tuning. In various embodiments, a gate dielectric layer is formed over a substrate, and a work-function metal layer is deposited over the gate dielectric layer. The work-function metal layer has a first thickness. A pre-treatment process of the work-function metal layer may then performed, where the pre-treatment process removes an oxidized layer from a top surface of the work-function metal layer to form a treated work-function metal layer. The treated work-function metal layer has a second thickness less than the first thickness. In various embodiments, after performing the pre-treatment process, another metal layer is deposited over the treated work-function metal layer.