TMD Monolayer Coatings for Flat Optics With Clean Etching
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Solution Overview
Problem
Existing flat optical devices face challenges in integrating materials with poor etch-selectivity and cross-contamination, and materials like graphene lack a bandgap, affecting light absorption and refraction.
Innovation Solution
A flat optical device with a coating layer comprising monolayers of transition metal dichalcogenides such as MoS2, WS2, WSe2, MoSe2, MoTe2, TiS2, ZrS2, ZrSe2, HfS2, PtS2, and SnS2, which are deposited over optical device structures to improve light absorption and refraction, with a capping layer for protection and etch-stop functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If semiconductor materials like germanium are used for coating, then light absorption and refraction are improved, but etch-selectivity is poor and cross-contamination occurs
Solution Approach 1:
The patent changes the material parameter from conventional semiconductor materials (germanium) to transition metal dichalcogenides (MoS2, WS2, WSe2, MoSe2, MoTe2). This material substitution maintains light absorption capabilities while providing superior etch-selectivity and eliminating cross-contamination issues, directly resolving the technical contradiction between optical performance and manufacturing ease
Solution Approach 2:
The patent employs composite material structures by combining transition metal dichalcogenide monolayers with underlying optical device structures (antennas, waveguides) and overlying capping layers. This composite approach enables the coating to provide both optical functionality and manufacturing compatibility through the synergistic properties of different material layers
2Illumination intensity
If graphene is used for coating, then light absorption is achieved, but bandgap is absent and light absorption is affected by Fermi energy level changes
Solution Approach 1:
The patent changes the material parameter from graphene to transition metal dichalcogenides, which possess intrinsic bandgaps (e.g., MoS2 has a bandgap of approximately 1.8 eV). This fundamental material parameter change provides stable light absorption characteristics that are not affected by Fermi energy level variations, directly resolving the reliability issue while maintaining optical absorption capability
Solution Approach 2:
The patent utilizes monolayer thickness of transition metal dichalcogenides, which provides sufficient optical absorption in a single atomic layer. This ultrathin coating achieves the required optical performance with minimal material, analogous to using the thinnest possible effective layer rather than thicker, less efficient materials
3Productivity
If optical device structures are reduced to sub-micron dimensions, then device integration is improved, but manufacturing precision becomes more difficult
Solution Approach 1:
The patent introduces transition metal dichalcogenide monolayers as an intermediary coating between the optical device structures and the etching environment. This intermediary layer provides excellent etch-selectivity, enabling precise etching of sub-micron structures without damaging underlying layers or causing cross-contamination, thus resolving the precision issue while maintaining high device integration
Solution Approach 2:
The patent applies ultrathin monolayer coatings specifically at critical interfaces where etch-selectivity is needed, rather than uniform thick coatings throughout the device. This localized application of the TMD coating provides precise etching control at sub-micron dimensions while minimizing material usage and maintaining manufacturing feasibility
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 solution enhances photon emission efficiency, reduces critical dimensions, and improves light guidance with high indirect band gaps, enabling direct integration with small pitch and thin CMOS devices while maintaining transparency and reducing surface roughness.
Implementation Method 1
semiconductor materials, such as germanium (Ge) are capable of absorbing and refracting light
Implementation Method 2
semiconductor materials, such as germanium (Ge) are capable of absorbing and refracting light
Implementation Method 3
these materials are difficult to integrate with the optical device structures of the flat optical device due to poor etch-selectivity and cross-contamination
Implementation Method 4
maintaining transparency and reducing surface roughness
Implementation Method 5
improves light guidance with high indirect band gaps
Data Source
Figure 1A
Figure 1B~1C
Figure 2A~2B
AI summary
Embodiments described herein relate to flat optical devices with a coating layer including monolayers selected from the group consisting of molybdenum disulfide (MoS2), tungsten disulfide (WS2), tungsten diselenide (WSe2), molybdenum diselenide (MoSe2), molybdenum ditelluride (MoTe2), titanium disulfide (T1S2), zirconium disulfide (ZrS2), zirconium diselenide (ZrSe2), hafnium disulfide (HfS2), platinum disulfide (PtS2), tin disulfide (SnS2), or combinations thereof. The coating layer is disposed over a plurality of optical device structures of the optical device. The monolayers may alternate between the materials to form the coating layer or may be a uniform coating layer of a single material. The coating layer is disposed over each optical device structure of the plurality of optical device structures.