Local melting with scanning tunneling microscopy and its application: Micro-bonding between silicon and glass at room temperature

During the STM-based surface modification process, the phenomena of tip-sample interaction in the case of sample bias voltage were studied in the paper. It's found that the high local current density in the tip-to-sample spacing can raise the temperature in a very small volume near the surface of sample. The local high temperature environment resulted to local melting of SiO₂ glass substrate with Cr film coating. During the modification process, the Si tip oscillated with large amplitude and inserted into the glass substrate due to attractive capillary force of molten liquid. The surface can be modified and a Cr-rich hillock formed in the scanning process. A jump-to-contact mechanism can be applied to explain the surface modification process. In some special conditions, the Si tip can be bonded with glass substrate in the area on micrometer scale. The bonding strength is high. The micro-bonding technique can be applied for assembly and repair of complicated MEMS.