Recent development and application of the XSTM

The development of the cross-section scanning tunneling microscope (XSTM) 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 samples, 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 found to be preferable in obtaining a flat {111} cross-section from both {111} and {001} wafers. Our devices in the mounting angle and the guiding line for the cleavage are also described in detail. Using this XSTM, we observed the {111} cleaved cross-sectional surface of the B-implanted Si{lll} wafer. The local surface structure was found to change on 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 found 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 was determined by the site and the sample bias dependence of protrusions in STM images.