SCANNING TUNNELING MICROSCOPY WITH BORON-DOPED DIAMOND TIP FOR IN-SITU PROFILOMETRY AND FINISHING IN DIAMOND MICRO-TURNING MACHINES

Abstract

The development of diamond micro-turning methods to improve the quality of micro- and nano-dimensional characteristics of parts is critical for many areas of optics, electronics, space technology, nanotechnology and others. The main problems of the existing methods of diamond micro-turning are the processing of the center of the part and the need to extract the part from the machine for nanoscale evaluation of surface quality. To solve these problems, we have proposed a new scheme for combining scanning tunneling microscopy (STM) with boron-doped diamond tip/cutter and a diamond micro-turning machine. After the standard diamond turning procedure, the STM performs a linear scan of the part surface in several diagonal directions with the stationary part. When defective areas are detected, a quick non-raster scanning procedure of the defective area is performed at a constant height mode and contact nanoprocessing of the defective area is performed. We presented techniques to grow boron-doped single crystals diamond for STM tips/cutters. To determine the optimal level of boron content in the diamond tip/cutter of the combined STM, the reliably measured values ​​of the tunneling current were analyzed at the maximum bias for tunneling and the minimum possible tunneling gap in the STM tip system. It is found that diamonds with a charge carrier concentration of at least 8×10¹⁰ cm^-3, that corresponds to a boron concentration in diamond ≈100 ppm, should be used during finishing and profilometry of silicon surface, and boron concentration in diamond tip should be at the level of ≈10 ppm during processing and scanning of metal surface.