Titanium film with about 3nm thickness is deposited on SiO2-Si substrate with dual facing targets sputtering method. Nano-oxidation lines are fabricated on this Ti film with various biased voltages and for the first time, current monitoring is performed during the oxidation process using a contact-mode AFM. In the cases of all lines, a flow of current began immediately when the biased voltage was applied and it kept almost unchanged as each of the oxide line was growing. The level of detected currents during the fabrication of oxide lines on Ti film is in the microampere (μA) level. The detected currents increase linearly with the biased voltages, which indicates that the detected current is mainly tunneling current. Thus, the process of nano-oxidation of Ti film is controlled either by the tunneling of electrons or holes through the Ti/water interface.
With the development and application of nanofabrication on nano photoelectron device, the completely oxidized thin metal film such as titanium film by Atomic Force microscope (AFM) tip induced oxidation method has been used to make various nano electric devices. It is more and more important to study the process mechanism for improving the operational stability and reliability of such nano devices. In this paper, the mechanism of AFM tip induced oxidation is analyzed with several aspects. According to the experimental results of AFM tip induced oxidation of titanium under various voltage biases and scanning speeds, we find that the height of the titanium oxidation is linear with the voltage bias and with the negative log of the scanning speed. Based on the formers’ theories, the mechanism and the theoretical modeling of AFM tip induced oxidation are improved. By setting the proper conditions such as voltage bias of 8V and
scanning speed of 0.1μm/s, good nanofabrication results with AFM oxidation of titanium are got and the oxide lines are with good aspect ratio and good continuity.