Chromium Nitride Gate Layers With High Work Function Deposition
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Solution Overview
Problem
Conventional gate electrode materials in CMOS devices, such as doped polysilicon, face challenges with surface depletion and non-ideal effective work function, particularly in advanced node applications, where higher work function values are required, and existing alternatives like titanium nitride may not suffice for all applications.
Innovation Solution
The formation of chromium nitride layers using a thermal cyclical deposition process, which involves providing a chromium precursor and a nitrogen reactant in a reaction chamber, without the use of plasma or plasma-activated species, to achieve high work function values suitable for gate electrodes in CMOS devices 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 can be manufactured with conventional processes, but the gate electrode exhibits surface depletion and non-ideal effective work function in advanced node applications
Solution Approach 1:
The patent changes the material composition parameter from doped polysilicon to chromium nitride, which fundamentally alters the work function characteristics and eliminates surface depletion effects. This material substitution enables achieving ideal effective work function for both NMOS and PMOS devices without relying on threshold voltage adjustment implantation processes.
Solution Approach 2:
The patent employs chromium nitride as a composite material that combines the benefits of high work function (suitable for PMOS) with good conductivity and stability. This composite material approach replaces the conventional doped polysilicon while providing superior electrical characteristics and eliminating the need for additional threshold voltage adjustment processes.
2Reliability
If titanium nitride layer is used to replace polysilicon gate material, then the effective work function improves, but the work function value is not high enough for PMOS regions requiring higher work function values
Solution Approach 1:
The patent changes the material parameter from titanium nitride to chromium nitride, which inherently provides a higher work function value. This material substitution directly addresses the insufficient work function of titanium nitride for PMOS applications while maintaining the benefits of plasma-free deposition processes.
3Productivity
If plasma or plasma-activated species are used in the deposition process, then the deposition efficiency is improved, but the process complexity and potential damage to the substrate increase
Solution Approach 1:
The patent extracts and eliminates the plasma component from the deposition process, using only thermal cyclical deposition with chromium precursors and nitrogen reactants. This removal of plasma simplifies the process while maintaining deposition efficiency and avoiding plasma-related substrate damage or process complexity.
Solution Approach 2:
The patent substitutes the plasma-based deposition mechanism with a thermal decomposition mechanism. Instead of using plasma-activated species for deposition, the process relies on thermal energy to decompose chromium precursors and form chromium nitride layers, thereby eliminating plasma complexity while maintaining productivity.
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 chromium nitride layers exhibit high work function values, addressing the limitations of conventional gate electrode materials by providing a suitable alternative for CMOS devices and other applications, such as DRAM, with improved performance and reduced complexity in threshold voltage adjustment.
Implementation Method 1
depositing a layer comprising chromium nitride onto a surface of the substrate. The deposition process can include (e.g., sequentially and separately) providing a chromium precursor to the reaction chamber and providing a nitrogen reactant to the reaction chamber
Data Source
AI summary
Methods and systems for depositing chromium nitride layers onto a surface of the substrate and structures and devices formed using the methods are disclosed. An exemplary method includes using a deposition process, depositing a chromium nitride layer onto a surface of the substrate. The deposition process can include providing a chromium precursor to the reaction chamber and separately providing a nitrogen reactant to the reaction chamber. The deposition process may be a thermal cyclical deposition process.