Characterization of nanometer scale titanium film oxidation lines and mim tunneling junction structures

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 the basic structure of the PCSS. The substrate is LT-GaAs or oxygen ion implanted SOS material. Above it, there is a 3∼5nm thick sputtered Ti film that are fabricated into MIM structure by the Atomic Force Microscope (AFM) using anodic induced oxidation method combined with photo lithography method. The chemical/physical characteristics of nano Ti film and nano oxidation line determine the operating property and reliability of such nano devices. In this paper, the characteristics of nano Ti film, nano oxidation lines and MIM junctions are measured by AFM, X-ray Photoelectron Spectroscopy (XPS) and semiconductor analyzer. The nano-oxidation lines are fabricated under air ambient, room temperature, the relative humidity is about 30%, oxygen density is about 20% and with tip scan speed is about 0.1μm/s during the fabrication process. The results indicate that with various bias voltages between AFM tip and Ti film during fabrication, different line width and different MIM’s I–V characteristic can be obtained, and the methods mentioned above optimized the fabrication conditions further.