Electronic and optical applications of electrón beam lithography on insulating substrates

L. ARZUBIAGA; F. GOLMAR; F. CASANOVA; M. SCHNELL; P. ALONSO; R. HILLENBRAND; L. HUESO

Oviedo, España

Conferencia; NANOLITHO 2010, 4th Spanish Workshop on Nanolithography; 2010

Centro de Investigación en Nanomateriales y Nanotecnología

There is a current demand of advanced lithographic techniques for both the fabrication of emerging research devices and the study of materials at nanometre level [1, 2]. Electron beam lithography (EBL) offers great advantages for building such nanoscale devices at high resolution. EBL allows transferring a pattern to a substrate by means of an electron-sensitive polymer (e-beam resist), which is exposed with an electron beam. However, diverse fabrication procedures might be needed depending on the conditions in which this technique is going to be used and the properties of the materials under study. For instance, it is especially difficult patterning directly with an electron beam on insulating substrates. The aberrations produced by the charge accumulation give way to mismatching of features in the transferred pattern. Our work has focused on the search of a suitable procedure and working conditions for performing EBL on insulating substrates. A strategy was proposed for overcoming the problem of charge accumulation and each step of the EBL process was then optimized. We present two practical examples for the proposed protocol: 1) Fabrication of nanogap electrodes on hafnium oxide (HfO2) thin films grown on glass. Electrodes with well-defined and smooth edges and a gap of around 40nm were obtained [Figure 1]. 2) Fabrication of infrared radiation antennas on calcium fluoride (CaF2) substrates, with a minimum feature size of 50 nm [Figure 2].