CHARACTERIZATION OF NANOMETER SCALE TITANIUMFILM OXIDATION LINES AND MIM TUNNELINGJUNCTION STRUCTURES

摘要

In the novel photoconductive semiconductor switch (PCSS)used in ultra-high speed electric-opto sampling system (EOS),the nanometre scale metal-oxide-metal (MIM) junction is thebasic structure of the PCSS. The substrate is LT-GaAs oroxygen ion implanted SOS material. Above it, there is a3～5nm thick sputtered Ti film that are fabricated into MIMstructure by the Atomic Force Microscope (AFM) usinganodic induced oxidation method combined with photolithography method. The chemical/physical characteristics ofnano Ti film and nano oxidation line determine the operatingproperty and reliability of such nano devices. In this paper,the characteristics of nano Ti film, nano oxidation lines andMIM junctions are measured by AFM, X-ray PhotoelectronSpectroscopy (XPS) and semiconductor analyzer. The nanooxidationlines are fabricated under air ambient, roomtemperature, the relative humidity is about 30%, oxygendensity is about 20% and with tip scan speed is about 0.1μm/sduring the fabrication process. The results indicate that withvarious bias voltages between AFM tip and Ti film duringfabrication, different line width and different MIM's I-Vcharacteristic can be obtained, and the methods mentionedabove optimized the fabrication conditions further.