Metal Carbon Nitride Gate Stabilization
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Solution Overview
Problem
Tungsten carbon nitride layers in MOSFET devices suffer significant tungsten loss during post-deposition processing, leading to reduced reliability and non-ideal work function values, which complicates the development of gate materials for advanced semiconductor devices.
Innovation Solution
A method involving the formation of a treated metal carbon nitride surface and/or a capping layer overlying the MCN layer, using in-situ surface treatments such as halogen-containing, nitrogen-containing, carbon-containing, and metal-containing reactants, applied through processes like plasma or cyclical chemical vapor deposition to mitigate metal loss and tune properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If tungsten carbon nitride is used as gate metal to provide ideal effective work function, then the work function compatibility with semiconductor material is improved, but significant tungsten loss occurs during post-deposition processing reducing reliability
Solution Approach 1:
A capping layer is formed over the tungsten carbon nitride layer before post-deposition processing to prevent tungsten loss in advance. This preliminary protective action ensures that the tungsten remains stable during subsequent processing steps while maintaining the desired work function properties.
Solution Approach 2:
The capping layer acts as an intermediary between the tungsten carbon nitride layer and the processing environment, preventing direct interaction that causes tungsten loss. This intermediate layer protects the sensitive MCN layer while allowing the device to achieve its intended electrical characteristics.
2Adaptability or versatility
If as-deposited tungsten metal nitride is used to provide ideal effective work function, then the energy needed to extract electron is improved, but the desired work function values are not achieved
Solution Approach 1:
The work function of the tungsten carbon nitride layer is tuned by changing the deposition parameters, including nitrogen flow rate, deposition temperature, and precursor ratios. These parameter adjustments allow precise control of the work function value to match the specific requirements of NMOS or PMOS devices.
Solution Approach 2:
Different regions or depths of the gate structure are optimized for different properties. The tungsten carbon nitride layer composition and stoichiometry are locally adjusted through controlled deposition conditions to achieve the specific work function needed for the intended device type while maintaining overall structural integrity.
3Quantity of substance
If doped polysilicon is used as gate electrode material to provide conductivity, then the conductive property is improved, but gate depletion region forms appearing as extra gate insulator thickness
Solution Approach 1:
The patent replaces the conventional doped polysilicon gate material with a metal carbon nitride layer that provides superior electrical properties without the gate depletion issue. This material substitution eliminates the need for threshold voltage adjustment implants and provides more precise control over the effective gate thickness.
4Quantity of substance
If doped polysilicon is used as gate electrode material to provide conductivity, then the conductive property is improved, but threshold voltage adjustment implantation becomes increasingly complex as device geometries are reduced
Solution Approach 1:
The patent replaces the conventional doped polysilicon gate material with a metal carbon nitride layer that provides superior electrical properties without the gate depletion issue. This material substitution eliminates the need for threshold voltage adjustment implants and provides more precise control over the effective gate thickness.
Solution Approach 2:
The work function of the tungsten carbon nitride layer is tuned by changing the deposition parameters, including nitrogen flow rate, deposition temperature, and precursor ratios. These parameter adjustments allow precise control of the work function value to match the specific requirements of NMOS or PMOS devices.
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 method effectively reduces metal loss and maintains desired properties of the MCN layer, enhancing the reliability and scalability of MOSFET devices by stabilizing mechanical and electrical characteristics.
Implementation Method 1
applying the surface treatment includes a plasma process
Implementation Method 2
forming a deposited metal carbon nitride layer on the substrate
Data Source
AI summary
Methods of forming structures including a layer of metal carbon nitride (MCN) and of mitigating metal loss from and/or tuning the layer of metal carbon nitride are disclosed. Systems for forming the layers and mitigating metal loss and structures formed using the methods are also disclosed.