RECENT DEVELOPMENT AND APPLICATION OF THE XSTM

The development of the cross-section scanning tunneling microscope (XS TM) and its application to the study of the cross-section of boron(B)- implanted Si wafers are reported. To obtain a cross-section of wafer s amples, we examined the cleavage on the {111} plane in two ways. As a result the cleavage, by pushing the side of the sample wafer, vias fou nd to be preferable in obtaining a flat {111} cross-section from both {111} and {001} wafers. Our devices in the mounting angle and the guid ing line for the cleavage are also described in detail. Using this XST M, we observed the {111} cleaved cross-sectional surface of the B-impl anted Si{lll} wafer. The local surface structure was found to change o n the cleaved cross-section from the 7 x 7 to the (root 3 x root 3)R30 degrees reconstruction through the disordered phase. The change was f ound to be consistent with the depth profile of the implanted B in the Si wafer. The arrangement of B and Si atoms in the disordered phase w as determined by the site and the sample bias dependence of protrusion s in STM images.