Vanadium Nitride Electrode Layers for PMOS Work Function Tuning
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Solution Overview
Problem
Conventional semiconductor device scaling techniques face challenges in finding suitable conducting materials for gate electrodes, particularly for PMOS regions in CMOS devices, and for materials needed in MIM structures, DRAM capacitors, and VNAND cells, where higher work function values and tunable properties are required.
Innovation Solution
A method for depositing layers comprising vanadium, nitrogen, and another element such as molybdenum, tantalum, niobium, aluminum, or silicon using a chemical vapor deposition process in a reactor chamber, where precursors and reactants are carefully controlled to form layers with tunable properties for work function adjustment and threshold voltage tuning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional gate materials like titanium nitride are used, then the device structure is simple and manufacturing is easy, but the work function value is insufficient for PMOS regions requiring higher work function values
Solution Approach 1:
The patent employs composite materials by forming a gate electrode structure comprising multiple layers: a first gate electrode layer (titanium nitride), a second gate electrode layer (vanadium-based material with higher work function), and an optional third gate electrode layer. This composite structure combines materials with different work function values to achieve the desired higher effective work function for PMOS regions while maintaining manufacturing feasibility through established deposition processes.
Solution Approach 2:
The patent changes the material composition parameters of the gate electrode by introducing vanadium-based materials (such as vanadium nitride, vanadium oxynitride, or vanadium oxide) with inherently higher work function values (5.0-6.0 eV) compared to conventional titanium nitride (4.5-4.7 eV). This parameter change in material composition directly addresses the insufficient work function value problem while allowing tuning of the effective work function through compositional control.
2Reliability
If higher work function materials are used in gate electrodes, then the work function value improves for PMOS regions, but the device structure and material selection become more complex
Solution Approach 1:
The patent applies local quality by implementing a dual-layer or triple-layer gate electrode structure where different materials are strategically positioned: the titanium nitride layer provides good adhesion and interface quality, while the vanadium-based layer (with higher work function) is placed in specific regions or as a top layer to locally enhance the work function where needed for PMOS operation. This localized material placement achieves the required work function enhancement without unnecessarily complicating the entire device structure.
3Reliability
If new materials are used for MIM structures, DRAM capacitors, and VNAND cells, then the performance and tunable properties improve, but the manufacturing process becomes more complex
Solution Approach 1:
The patent achieves universality by developing a multi-functional vanadium-based material system that can serve multiple device types and applications. The same vanadium-based materials (nitride, oxynitride, oxide) and deposition processes can be used for gate electrodes in CMOS devices, MIM structures, DRAM capacitors, and VNAND cells, providing tunable properties (work function, stress, resistivity) across different device architectures without requiring entirely separate material systems for each application.
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 allows for the formation of layers with highly tunable electron work function, stress, and resistivity, suitable for use in gate stack work function tuning in PMOSFETS, MIM metal electrodes, and VNAND contacts, addressing the need for materials with higher work function values and improved performance in semiconductor devices.
Implementation Method 1
The deposition process comprises providing a first precursor to the reactor chamber, the first precursor comprising vanadium. In addition, the deposition process comprises providing a second precursor to the reactor chamber, the second precursor comprising an element selected from the list consisting of molybdenum, tantalum, niobium, aluminum, and silicon. In addition, the deposition process comprises providing a reactant to the reactor chamber, the reactant comprising nitrogen.
Data Source
AI summary
Disclosed are methods and systems for depositing layers comprising vanadium, nitrogen, and element selected from the list consisting of molybdenum, tantalum, niobium, aluminum, and silicon. The layers are deposited onto a surface of a substrate. The deposition process may be a cyclical deposition process. Exemplary structures in which the layers may be incorporated include field effect transistors, VNAND cells, metal-insulator-metal (MIM) structures, and DRAM capacitors.