/WS2 device fabrication using DUV lithography and dry resist

WS2 device fabrication using DUV lithography and dry resist

Leuven | More than two weeks ago

You will explore micro-lithography with solvent-free processing methods

Monolayer MX2 (transition metal dichalcogenides) are considered as alternative channel materials for advanced CMOS devices. The construction of CMOS transistors requires to develop a contact module, which aims at establishing an electrical connection between the MX2 layer and the outer world. In our lab flow, we use the lift-off approach for contacts on WS2, where resist is spun directly on the WS2, patterned by e-beam, contact metal is sputtered then the resist is developed. During development, the metal coated on the resist is removed (lift-off) and only the metal in contact with WS2 remains.


There are two main difficulties of the contact lithography module: first, the presence of residual polymers coming from the transfer step, hindering good electrical connection between the MX2 film and the deposited metal. First, the presence of residual resist which might not be developed correctly. Second, the adverse effect of solvents used for spinning and development of the resist. Fortunately, using the e-beam approach solves these two issues since the solvents used are acetone and anisole which does not modify the WS2. However, e-beam is a slow technique which requires significant resources. There is a significant interest to move to DUV resist based lithography, enabling faster and simpler device manufacturing. The goal of the master thesis is twofold: first, to set up protocol for DUV-based contact ‘lift-off’ lithography on WS2, using a specially designed dry resist. Second, the processing damage to the electrical properties of the WS2 will be studied using WS2 devices made by the new protocol.

Type of project: Thesis, Combination of internship and thesis

Duration: 6 months to 12 months

Required degree: Master of Science, Master of Engineering Technology

Required background: Chemistry/Chemical Engineering, Nanoscience & Nanotechnology, Physics

Supervising scientist(s): For further information or for application, please contact: Jean-Francois de Marneffe (Jean-Francois.deMarneffe@imec.be) and Marina Timmermans (Marina.Timmermans@imec.be)

Imec allowance will be provided for students studying at a non-Belgian university.

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