Microprobe array with electrical interconnection for thermal imaging and data storage

In this work, new novel methods for fabricating a thermal probe array with 32 × 32 probes on one chip are proposed. It consists of silicon micromachined probe, AIN actuator, pyramidal SiO₂ tip on which the nano-scale metal-metal junction is formed using a self-alignment technique. The nano-junction can be used as a thermocouple to measure a local temperature on a sample surface or as a nano-heater to make a local deformation on a media. In self-alignment process, a metal layer (Pt/Ni) is deposited on the inside of SiO₂ hollow tip fabricated by low temperature (950 °C) oxidation of silicon etch pit. This low temperature oxidation results in a smaller oxide thickness at the tip apex than other flat area. Therefore, after selective etching the SiO₂ in buffered HF, a small hole surrounding the Pt/Ti tip apex can be created. Another metal (Ni) is deposited outside the Pt/Ti tip to make the nano-junction. For electrical interconnection between the thermal probe and an IC chip, a hole array with 30 μm of a hole diameter is made by dry etching through the 150-μm-thick Pyrex glass, and then Ni is electroplated into the through etched-hole. Finally the Pyrex glass plate was anodically bonded to the probe array. Using the fabricated thermal probe, temperature distribution is measured on a prepared sample surface and the local heating capability of the thermal probe is confirmed. Preliminary experiments for data writing and reading are performed on a phase change medium.