Graphene Substrate Transfer on Etch-Resistant Insulative Layers
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Solution Overview
Problem
Existing methods for forming graphene on thinner substrates face challenges such as bowing and contamination, making it difficult to scale up the manufacture of electronic device precursors for commercial production, especially for substrates thinner than 50 μm and larger diameters.
Innovation Solution
A method involving a silicon wafer with a thin insulative layer and a polymer coating is used to form graphene, where the silicon wafer is thinned or removed through etching, with the insulative layer and polymer coating being resistant to etching to prevent contamination and damage to the graphene, allowing for the creation of a thin graphene-based electronic device precursor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If graphene is formed on thinner substrates using conventional methods, then substrate thickness is reduced, but substrate bowing and contamination occur
Solution Approach 1:
The substrate system is segmented into multiple functional layers: a thick support wafer providing mechanical stability, a thin insulative layer providing the actual substrate function, and graphene formed on top. This segmentation allows the thick wafer to prevent bowing while the thin insulative layer enables graphene formation without contamination.
Solution Approach 2:
The insulative layer acts as an intermediary between the support wafer and the graphene. It is resistant to etchants used to remove the support wafer, thereby protecting the graphene from contamination while allowing the support structure to be removed after serving its protective function during manufacturing.
2Length of moving object
If substrate thickness is reduced to below 50 μm, then device weight and thickness are reduced, but manufacturing reliability deteriorates due to bowing and contamination
Solution Approach 1:
The thick support wafer is provided in advance to prevent bowing during graphene formation. The insulative layer is formed on this support structure before graphene deposition, ensuring that the graphene forms on a stable, flat surface. The support wafer is removed only after these preliminary steps are complete, ensuring manufacturing precision is maintained throughout the process.
3Length of moving object
If conventional etching techniques are used to thin substrates, then substrate thickness is reduced, but graphene contamination and damage occur
Solution Approach 1:
The insulative layer serves as a protective intermediary during the etching process. It is specifically selected to be resistant to the etchants used to remove the support wafer, thereby acting as a barrier that prevents etchant contact with the graphene and avoids contamination and damage to the sensitive 2D material.
Solution Approach 2:
The support wafer is a disposable sacrificial element that provides mechanical support during manufacturing but is intentionally removed after serving its purpose. Its removal enables the final thin graphene-based device structure while the insulative layer remains to protect the graphene throughout the process.
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 method enables the production of high-quality, thin graphene-based electronic device precursors that are resistant to thermal insulation, suitable for use in heated environments, and reduces the need for recalibrations, while maintaining the electronic properties of graphene, thus overcoming the limitations of previous techniques.
Implementation Method 1
thinning the silicon wafer, or removing the silicon wafer to provide an exposed surface of the insulative layer, by etching with an etchant
Implementation Method 2
The method of WO 2017/029470 may be performed using vapour phase epitaxy (VPE) systems and metal-organic chemical vapour deposition (MOCVD) reactors
Implementation Method 3
metal-organic chemical vapour deposition (MOCVD) reactors
Data Source
AI summary
A method for the manufacture of an improved graphene substrate and applications therefor There is provided a method (100) for the manufacture of an electronic device precursor, the method comprising: (i) providing a silicon wafer (200) having a growth surface (205); (ii) forming (105) an insulative layer (210) on the growth surface (205) having a thickness of from 1 nm to 10 nm, preferably 2 nm to 1 nm; (iii) forming (110) a graphene monolayer or multi-layer structure (215) on the insulative layer (210); (iv) optionally forming (115, 120) one or more further layers (220) and/or electrical contacts (225, 230) on the graphene monolayer or multi-layer structure (215); (v) forming (125) a polymer coating (235) over the graphene monolayer or multi-layer structure (215) and any further layers (115) and/or electrical contacts (225, 230); (vi) thinning (130) the silicon wafer (200), or removing the silicon wafer (200) to provide an exposed surface of the insulative layer (210), by etching with an etchant, wherein the silicon wafer (200) is optionally subjected to a grinding step before etching; and (vii) optionally dissolving away (135) the polymer coating (235); wherein the insulative layer (210) and the polymer coating (235) are resistant to etching by the etchant. The resulting conductive graphene substrate can be used in (organic) LEDs, capacitor devices, tunnel FETs and Hall sensors.