Cyclical Molybdenum Nitride Gate Film for Reduced Gate Depletion
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Solution Overview
Problem
Conventional CMOS technologies using doped polysilicon as gate electrodes face issues such as gate depletion and non-ideal effective work function, which become significant in advanced technology nodes, leading to inefficiencies and complex threshold voltage adjustment implantation processes.
Innovation Solution
The use of a cyclical deposition process to deposit a molybdenum nitride film on a substrate, involving unit deposition cycles with a molybdenum halide precursor and a nitrogen precursor, to form a gate stack with a preferred effective work function for both NMOS and PMOS devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If doped polysilicon is used as gate electrode material, then the gate electrode can be formed with conventional processes, but gate depletion occurs creating extra gate insulator thickness and non-ideal effective work function
Solution Approach 1:
The patent changes the material parameter from doped polysilicon to metal nitride (such as molybdenum nitride), fundamentally altering the electrical properties of the gate electrode to eliminate gate depletion effects while maintaining manufacturability through cyclical deposition processes
Solution Approach 2:
The patent employs composite gate electrode structures combining metal nitride layers with other materials to achieve both low electrical resistivity and ideal effective work function characteristics, resolving the reliability issues of conventional polysilicon gates
2Ease of manufacture
If doped polysilicon is used as gate electrode material, then the gate electrode can be formed, but the effective work function is non-ideal for both NMOS and PMOS devices
Solution Approach 1:
The patent changes the material composition from polysilicon to metal nitride, which inherently provides ideal effective work function values for both NMOS and PMOS devices, eliminating the need for threshold voltage adjustment implantation processes
3Object-generated harmful factors
If threshold voltage adjustment implantation is used to correct non-ideal effective work function, then the work function can be adjusted, but the process becomes increasingly complex in advanced technology nodes
Solution Approach 1:
The patent extracts the effective work function control from post-fabrication implantation processes and integrates it into the gate electrode material selection itself, using metal nitride materials that inherently provide ideal work function values without requiring additional complex processing steps
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 molybdenum nitride film deposited using this method provides a low electrical resistivity gate electrode with an optimal effective work function, reducing gate depletion and improving semiconductor device efficiency, especially in advanced technology nodes.
Implementation Method 1
depositing a molybdenum nitride film directly on the surface of the substrate by performing one or more unit deposition cycles of a cyclical deposition process, wherein a unit deposition cycle comprises: contacting the substrate with a first vapor phase reactant comprising a molybdenum halide precursor; and contacting the substrate with a second vapor phase reactant comprising a nitrogen precursor
Data Source
AI summary
Methods for depositing a molybdenum nitride film on a surface of a substrate are disclosed. The methods may include: providing a substrate into a reaction chamber; and depositing a molybdenum nitride film directly on the surface of the substrate by performing one or more unit deposition cycles of cyclical deposition process, wherein a unit deposition cycle may include, contacting the substrate with a first vapor phase reactant comprising a molybdenum halide precursor, and contacting the substrate with a second vapor phase reactant comprising a nitrogen precursor. Semiconductor device structures including a molybdenum nitride film are also disclosed.