Chang-wook Moon

Patterned Pyroelectric Electron Emitters and their Feasibility Study for Lithography Applications

Patterned electron emitters were fabricated using LiNbO3 (LN) single crystals and their characteristics were investigated for electron-beam lithography applications. Pyroelectrically induced electron emission was suppressed by coating Pt and Ti thin films. However, the electron emission behaviors were not affected by the deposition of SiO2 dielectric layers. Based on these observations, a structure of patterned emitters was suggested; Ti layers and SiO2 layers were used as blocking layers and emission layers, respectively. By using a 1:1 electron beam projection system, 100 µm and 5 µm dots on the exposed resist were obtained from 300 µm and 30 µm dots on emitters. Reduction of patterns might be useful in obtaining fine patterns without complex electron optics.

Self-focused electron beams from pyroelectric LiNbO3 crystals and their pattern-replication capability

We investigated the characteristics of electrons emitted from LiNbO3 single crystals using a current detector and a 1:1 electron projection system. Exposure to a poor vacuum of 10−1Torr restored the screening charges to the crystal during discharge and enabled reproducible electron emission within 1min. We fabricated a patterned Si thin-film mask layer on a LiNbO3 crystal. As conducting thin films suppressed the pyroelectric electron emission from LiNbO3, we could transfer the mask pattern of an array of 10-μm dots to an electron-beam resist using the projection system. The electron beam from the crystal was highly self-focused, and the pattern replication needed neither an electric nor a magnetic field.

Feasibility studies on pyroelectric emission for lithography application

Abstract Electron beam patterns of ferroelectric switching emission, dielectric emission, and field emission were studied by patterning images on electron beam resist. It was observed that the pyroelectric emission is most acceptable for an 1:1 electron projection lithography application. Effects of the initial kinetic energy of electrons and distance between the emitter and the collector on pattern resolution were discussed. An 1:1 electron projection lithography was demonstrated by patterned emitter.

Electron emission behaviors of ferroelectric materials

In this work electron emission generated by polarization switching of ferroelectrics has been investigated. In this work special measurement techniques were used to study the electron emission behaviors. Electron-beam resist coated wafers were used to obtain spatial distribution of the emitted electrons. Triglycine sulphate crystals was studied by varying experimental conditions and heat treatment conditions of the samples. Surface flashover plasma of a ferroelectric origin was observed on a polar ferroelectric surface. In our work plasma formation is proved by correlation between the main switching parameters and emission of electrons from ferroelectrics-coercive field and threshold field of emission.