Low energy electron beam lithography with microcolumn

Abstract

A miniaturized electron beam system whch is composed of a cold field emission tip, a source lens, a deflector and an einzel lens was fully fabricated and assembled with MEMS technology.''2 The production possibility of the microcolumn with MEMS technology was shown. This paper describes a fial structure of microcolumn system and the results of low energy electron beam lithography. Our system is divided into two parts. One is device part and the other is jig part. The devices consist of highly doped silicon wafers and pyrex glass wafers. Silicon wafers were used as electrodes and fabricated by deep RIE(Reactive Ion Etching) and pyrex glass wafers were used as a dielectric and bonding material between the silicon electrodes. The jig was fabricated by glass and tefron in order to assemble the devices and connect the wires. The final structure is shown in Fig 1. The use of low-voltage electron beam lithography to reduce proximity effects, improve throughput, and reduce substrate damage caused to underlying materials has been inve~tigated.~ Because the size of microcolumn is very small, we focus the low energy electron beam lithography. Lithography experiments were performed in vacuum chamber. Microcolumn and wafer coated with photoresist are mounted and the wires are connected to the feedthrough. PMMA 950K (Shipley Co., lOOnm thick) was used in this experiment. The energy of electrons can be varied as the voltage of tip. Fowler-Nordheim plot of tungsten cold field emission tip is shown in Fig 2. and the photographs of exposed patterns are shown in Fig 3. The applied voltage to the tip was -8OOV and wafer was OV. And a result of Monte-Carlo simulation with electron beam lithography simulator4 is shown in Fig 4. We will present experiment results compared with simulation.