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The scanning tunneling microscope (STM) invented by Binnig and Rohrer (1) can map out the topographic and electronic structures of a solid surface at the atomic level by means of a tiny metal tip. In addition to imaging the STM also provides a promising method for manipulating single atoms and processing materials at the atomic level. Preliminary demonstrations, such as the creation of single-atom bits on a germanium surface by Becker and colleagues (2) and the manipulation of single xenon atoms on a nickel surface by Eigler and co-workers (3), suggest the power of this approach. Challenges remain, however, in clearly understanding the physical mechanisms involved, as well as issues of technological feasibility.
Judging from Japan's success in microelectronics, and noting that miniaturization in conventional microelectronics will meet an ultimate limit sometime around the year 2010, it is natural to suppose that we will move toward atomic level material processing with the STM and related methods. Considerable progress has already been made in this field in Japan. Hosoki and colleagues (4) at the Hitachi Central Research Laboratory (HCRL) wrote the letters "PEACE '91 HCRL" on the surface of molybdenum disulfide by extracting sulfur atoms with an STM tip; each letter was only about 1.5 nm high. Although writing such letters itself has no significant value, it is one of the best ways to demonstrate the feasibility of creating bits for data storage and devices with a novel technique at the atomic to nanometer scales. Kobayashi and co-workers (5) of the Aono Atomcraft Project (AACP) Research Development Corporation of Japan (JRDC)! have written nanometer-scale letters on a silicon surface by extracting silicon atoms using an STM tip (see figure). (Figure omitted) They have also studied the physical mechanisms of the extraction of silicon atoms on the basis of extensive experiments (6), which have made it possible to extract single silicon atoms routinely (7). Iwatsuki and co-workers (8), JEOL Corporation, also wrote nanometer-scale lettering on a silicon surface with a similar method using a stable STM...