Lithography can modify or deteriorate the sample properties e.g. by exposure to high-energy charged particles like electrons or ions. This can lead to unwanted creation of covalent bonds with the organic resist, trapped charges or lattice defects. The resulting contaminations or defects can strongly deteriorate the device performance when using chip designs with insulating layers or devices comprising sensitive materials like 2D materials or nanowires.
The heated tip of the standard NanoFrazor lithography process only heats the top resist layer. Sensitive materials below the resist stack are not heated perceptibly and remain completely unharmed during patterning of the top resist layer.
The NanoFrazor can be also incorporated inside a glovebox. This facilitates nanolithography on samples that deteriorate in air.
Superior electrical contacts on MoS2
A side-by-side comparison of NanoFrazor- and electron beam lithography (EBL)-patterned contact electrodes on single-layer MoS2 flakes. EBL produced thickened edges and left residues of the PMMA resist, which were not removed in a standard developing process. After NanoFrazor patterning and developing, no evidence of such artifacts was observed. The electrical quality of the metal contacts patterned by NanoFrazor was significantly superior enabling record-breaking transistors. Courtesy of Prof. Elisa Riedo, NYU, publication Zheng et al. Nat. Electr. 2019
Top-gates for InAs nanowire transistors
Indium arsenide (InAs) nanowires are notoriously sensitive to trapped charges. Gate oxides are insulating and charge introduced by electron beam lithography is difficult to remove and deteriorate the device performance by strongly shifting the switching voltage. Such trapped charges are typical the fabrication with electron beam lithography. The InAs nanowire device with high resolution top gates fabricated by NanoFrazor lithography switched exactly as 0 V and close to the theoretical limit of 60 mV/dec. Courtesy of IBM Research Zurich, publication 2019
Contacts to single-walled carbon nanotubes
Single-walled carbon nanotubes (SWNTs) have remarkable electrical properties, which are also very sensitive to changes in the environment. That’s why contacting them is a critical step in fabrication of high-performance SWNT devices. SWNTs tend to be spread randomly on the substrate surface and are often imaged and patterned using focused electron beams. This process leads to the material damage and impurities deposition. Using NanoFrazor lithography, the SWNTs can be located and contacted without any exposure to charged particle beams, enabling characterization of the intrinsic SWNT properties. In collaboration with Prof. Tai-Cheng Lee, NTU, Taiwan