Vanadium Nitride Gate Layer Deposition for CMOS Work Function Control
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Solution Overview
Problem
Conventional gate electrode materials in CMOS devices, such as doped polysilicon, face challenges with gate depletion and non-ideal effective work function, particularly in advanced node applications, necessitating alternative materials with higher work function values for improved performance.
Innovation Solution
Formation of vanadium nitride-containing layers using a thermal cyclical deposition process, involving vanadium and nitrogen precursors, to achieve high work function values suitable for gate electrodes and other applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If doped polysilicon is used as gate electrode material, then the device structure is simple and manufacturing is easy, but gate depletion occurs and effective work function is non-ideal
Solution Approach 1:
The patent uses a composite material structure consisting of a titanium nitride layer and a vanadium nitride layer. The titanium nitride layer provides good conductivity and adhesion, while the vanadium nitride layer provides the desired high work function. This composite structure resolves the contradiction by combining materials with complementary properties to achieve both ease of manufacture and reliable electrical characteristics without gate depletion issues.
2Ease of manufacture
If doped polysilicon is used as gate electrode material, then the manufacturing process is simple, but the effective work function is non-ideal for advanced node applications
Solution Approach 1:
The patent changes the material parameters by transitioning from doped polysilicon to a nitride-based composite material system. Specifically, the vanadium nitride layer is engineered to provide a work function greater than 4.6 eV, which is a significant parameter change from conventional materials. This parameter change enables precise control of threshold voltage and effective work function, meeting the stringent requirements of advanced node applications while maintaining a relatively simple deposition-based manufacturing process.
3Manufacturing precision
If titanium nitride layer is used to replace polysilicon, then effective work function is improved, but higher work function values are still needed for PMOS regions
Solution Approach 1:
The patent applies local quality by using different material compositions and thicknesses in different regions of the gate electrode structure. The vanadium nitride layer can be selectively applied or varied in thickness to achieve different work function values tailored to specific device regions (e.g., higher work function for PMOS, lower for NMOS). This enables the same base structure to be adapted for different device types and performance requirements, enhancing versatility while maintaining precise work function control.
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 vanadium nitride-containing layers provide improved work function values, addressing the limitations of doped polysilicon and enabling more efficient threshold voltage adjustment and performance in CMOS devices.
Implementation Method 1
depositing a vanadium nitride-containing layer onto a surface of the substrate, wherein the deposition process comprises providing a vanadium precursor to the reaction chamber and providing a nitrogen precursor to the reaction chamber
Data Source
AI summary
Methods of forming a vanadium nitride-containing layer. The method comprises providing a substrate within a reaction chamber of a reactor and depositing a vanadium nitride-containing layer onto a surface of the substrate, wherein the deposition process comprises providing a vanadium precursor to the reaction chamber and providing a nitrogen precursor to the reaction chamber. The disclosure further relates to structures and devices comprising the vanadium nitride-containing layer.