Nanofog Oxide Seeding for High-k Deposition on Inert 2D Surfaces
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Solution Overview
Problem
Existing methods for forming high-k gate oxides on inert 2D semiconductor surfaces, such as graphene and TMDs, often result in defective oxide layers due to surface functionalization and reactive gas treatments, leading to high leakage currents and degradation of electronic properties.
Innovation Solution
The development of a low-temperature atomic layer deposition (ALD) technique that directly deposits thin, uniform Al2O3 nanoparticles on inert surfaces without prior functionalization, which can be used as a seeding layer for subsequent high-k oxide deposition, enabling the formation of bilayer stacks with improved dielectric properties and reduced equivalent oxide thickness (EOT).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If surface functionalization methods (chemical treatment, reactive gases) are used to deposit oxide on inert surfaces, then oxide deposition is achieved, but defects are introduced and electronic properties are degraded
Solution Approach 1:
The patent introduces an intermediary organic seeding layer (such as PTCDA or TiOPc) that is first deposited on the inert 2D semiconductor surface, then serves as a nucleation site for subsequent oxide deposition. This intermediary layer mediates between the inert substrate and the oxide, enabling defect-free oxide formation without direct chemical treatment of the semiconductor surface.
Solution Approach 2:
The patent performs preliminary deposition of an organic seeding layer before oxide deposition. This preliminary action prepares the surface by creating nucleation sites that enable subsequent uniform oxide growth, avoiding the need for harmful chemical treatments during the oxide deposition process.
2Reliability
If chemical treatment methods (NOx, O3) are used for surface functionalization, then oxide deposition is enabled, but unwanted doping occurs and electronic properties are degraded
Solution Approach 1:
The organic seeding layer acts as a protective intermediary that prevents direct interaction between reactive chemical treatments and the 2D semiconductor surface, thereby avoiding unwanted doping while still enabling oxide deposition on the seeding layer.
Solution Approach 2:
The patent extracts the harmful chemical treatment step from the process by replacing it with organic seeding layer deposition followed by oxide growth on the seeding layer, thereby separating the oxide deposition function from the harmful chemical interactions with the semiconductor.
3Reliability
If polymer based seeding layers are used, then oxide deposition on inert surfaces is achieved, but processing time is increased
Solution Approach 1:
The patent changes the material parameter of the seeding layer from polymer-based to small organic molecules (PTCDA, TiOPc) that can be deposited more rapidly via sublimation, thereby reducing processing time while maintaining the seeding function.
Solution Approach 2:
The patent uses thin films of organic molecules as disposable seeding layers that are quickly deposited and then serve their purpose for oxide nucleation, replacing longer-processing polymer-based seeding approaches.
4Manufacturing precision
If MBE deposited TiOPc monolayer is used as seed layer, then uniform AlOx deposition is achieved, but the technique is not suitable for 3D structures due to directional deposition
Solution Approach 1:
The patent develops an ALD-based oxide deposition process on organic seeding layers that is universal and can be applied to both 2D and 3D structures, replacing the MBE technique which is limited to planar substrates due to its directional deposition characteristic.
Solution Approach 2:
The patent replaces the physical vapor deposition mechanism of MBE with the chemical vapor deposition mechanism of ALD, which provides conformal coverage on 3D structures through surface reaction rather than directional condensation.
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
This approach eliminates the need for surface functionalization, achieves pin-hole-free and continuous Al2O3 films, and allows for the deposition of high-k gate dielectrics on both 2D and 3D structures, including inert metals, resulting in improved electrical properties and reduced leakage currents, making it suitable for various semiconductor devices.
Implementation Method 1
low-temperature atomic layer deposition (ALD) technique that directly deposits thin, uniform Al2O3 nanoparticles on inert surfaces
Implementation Method 2
the nanofog can also consists of sub 1 nm particles. Oxide layers can be formed on the nanofog
Data Source
AI summary
A semiconductor structure includes a nanofog oxide adhered to an inert 2D or 3D surface or a weakly reactive metal surface, the nanofog oxide consisting essentially of 0.5-2 nm Al2O3 nanoparticles. The nanofog can also consists of sub 1 nm particles. Oxide layers can be formed on the nanofog, for example a bilayer stack of Al2O3—HfO2. Additional examples are from the group consisting of ZrO2, HfZrO2, silicon or other doped HfO2 or ZrO2, ZrTiO2, HfTiO2, La2O3, Y2O3, Ga2O3, GdGaOx, and alloys thereof, including the ferroelectric phases of HfZrO2, silicon or other doped HfO2 or ZrO2. The structure provides the basis for various devices, including MIM capacitors, FET transistors and MOSCAP capacitors.