New ultra high resolution Electron Beam Lithography in Winfab
The micro- and nano-fabrication platform - WINFAB - has acquired a new Ultra high-resolution Electron Beam Lithography (EBL) equipment.
The system consists in a high resolution Scanning Electron Microscope equipped with an additional lithography module allowing an accurate control of the electron beam scanning. The combination of these tools enables the definition of extremely small patterns with dimensions down to 10 nm. The system has been funded by a GEQ FNRS project.
Lithography in micro- and nano-fabrication
Micro- and nano-lithography techniques refers to the capability to draw a specific pattern with micrometric/nanometric dimensions into a sensitive resist layer coated on the surface of a substrate.
Standard optical lithography consists in transferring the design from a predefined optical mask to a photosensitive layer by UV exposition.
While photolithography is a fast and powerful technique, its resolution is limited by the wavelength of light, generally to a value of ~ 0.5 µm.
To achieve smaller features, an advanced lithography technique, like EBL, is required.
In this technique, the electron beam of an electron microscope, which has a diameter < 2nm, is used to directly draw the patterns onto an electron sensitive resist layer coated on the sample’s surface.
It is a maskless technique with a less than 10 nm spatial resolution.
The new EBL system is equipped with a laser interferometry stage that allows sample’s positioning with a less than 2 nm accuracy.
It is then possible to perfectly align several successive lithographies or to draw large pattern, i.e. larger than the writefield defined by the microscope’s magnification, by field stitching.
High resolution imaging and metrology
Since the system is built from an electron microscope, it allows high-resolution SEM imaging. Coupled with the laser interferometry stage capabilities, the system turns into an advanced metrology tool that can precisely measure devices’ position or displacement (for example for MEMS devices) in a fully automated way.
Research
Several research projects are already envisioned with this new tool, including the development of molecular sensing platforms based on 2D materials, the fabrication of tailored scanning probes tips with specific functionalities like temperature measurements or SQUID-on-tip, or the fabrication of magic-angle twisted bilayer graphene devices.
Additionally, beyond these research subjects, the EBL will be accessible to all users of the Winfab platform.
Any researcher interested in developing a new activity on the system can contact the WINFAB staff for more information.