Etch Systems

The nanoETCH benchtop system is optimised for soft-etching & flourine-chemistry etching of substrates up to 6″ diameter. Originally developed in collaboration with the graphene group at the National Graphene Institute at the University of Manchester, UK by the requirement for an etching tool that allowed for precision etching of sensitive 2D materials — not available in conventional RIE tools.

The nanoETCH has been optimised to provide Soft Etching of carbon nanomaterials, particularly graphene with Ar and/or O2 gases. The optional Flourinated Process Gas module extends the Soft Etching range to include fine-etch control of harder materials such as 2D materials beyond graphene such as hBN and MoS2 as well as SiO2 and Si.

nanoETCH tools can be fitted with stages for 3″/75mm, 4″/100 mm or 6″/150 mm maximum substrate diameters.

Today, nanoETCH tools are installed globally in leading graphene/2D material research labs including ICFO (Spain), the Cambridge Graphene Centre and the UK National Graphene Institute.

Soft Etching

Soft Etching is the application of precisely-controlled low powers for etching applications involving highly sensitive materials (such as graphene) or where ultra-low etch rates are needed. This allows for the routine use of plasma powers <5 W (down to 100 mW or below, subject to configuration and process), with up to 10 mW control resolution.

Examples of applications of Soft Etching are:

• Substrate preparation for mechanical exfoliation: When preparing 2D material ‘flakes’ via mechanical exfoliation (also known as the sticky-tape method), the nature of the substrate surface is crucial. Soft Etching tools are now being used to obtain the topological and chemical substrate surface properties necessary for producing large flake areas.
• 2D material patterning: Given their thinness, 2D materials are fragile and require finely-controlled etching conditions for device fabrication. Soft Etching technology provides this control and also allows for patterning without cross-linking common mask photoresists (e.g., PMMA).
• Defect engineering: A key research theme for graphene science is defect engineering. Through controlled low plasma-powers, soft-etching technology is being used for creating point defects in lattices for implementing control over this aspect of the material. Fine control is necessary for reproducible results and to avoid uncontrolled material destruction.

For Soft Etching with graphene and 2D materials, tools are typically fitted for Ar and O2 process gases.

Fluorine-Chemistry Etching

For more aggressive etch processes, nanoETCH systems can be configured for use with the fluorine-chemistry etchant gases SF6 or CHF3. For this, tools are equipped with a range of hardware and software enhancements.

Recent applications of fluorine-chemistry nanoETCH tools have included:

• h-BN sidewalls: A pit was etched into a multi-layer stack of h-BN, using Moorfield etching technology contained within a MiniLab 026. With SF6 as the etchant gas and a Soft Etching approach, just 7–8 layers of material were removed during a 2 minute process. Residual roughness at the bottom of the pt was just 1 atomic layer.
• h-BN bulk etching: By changing conditions, much higher etch rates were possible. Users were able to achieve an etch depth of 130 nm at a rate of 1.1 nm/s.
• SiO2 etching: A thermally oxidised Si wafer was etched using a nanoETCH tool using CHF3 as etchant gas. An ultra-low etch rate of ~1.3 Å/s was obtained, allowing for excellent control.