Nano-fabrication on silicon at high temperature in a UHV-STM

The microscopic manipulation of atoms at high temperature has been attempted for the first time. A UHV-STM used for this experiment is designed to facilitate sample heating up to 1300 °C after sample introduction. The UHV-STM employs stacked piezoelectric elements to control the three-dimensional drive of the tip. Nano-fabrication utilizes this fine positioning mechanism and the imaging capability of the STM for ultrafine fabrication of the surface of a solid. The technique for nano-fabrication usually changes the bias voltage between the tip and sample during pattern writing while maintaining the tip-sample distance. This method is applied to a high-temperature silicon sample in which atoms on the sample surface are migrated towards the tip. As a result, a pyramid or a crater is formed on the sample. The method is very effective in fabrication on the atomic level due to thermal excitation of atoms. In the high-temperature nano-fabrication method, the temperature should be controlled as should the bias voltage, the tunnel current, and the distance between the tip and the sample. We succeeded in creating a hexagonal pyramid and crater on an Si(111) surface and a quadrangular pyramid on an Si(100) surface at 600 °C. (5 × 5) domains on the Si(111) surface can be observed on narrow terraces due to the relaxation of surface energy.