OBSERVATION OF THE BOTTOM SURFACE OF CONTACT HOLES BY HOPPING SCANNING ATOMIC-FORCE MICROSCOPY WITH A ZNO WHISKER TIP

In this article, it is demonstrated that atomic force microscopy (AFM) can be useful for observing surface microstructures on the bottom of contact holes used for large scale integrated devices. The AFM employs a zinc-oxide (ZnO) whisker tip with high-aspect ratio and a hopping s canning mode operation. In the hopping scanning mode operation, the pr obing tip is moved up and down with a period synchronized with the mov ement in the x direction to avoid collisions against the acute protrus ions. Some kinds of bottom surfaces of the contact holes with a diamet er of 1 mum and a depth of 1.5 mum have been successfully imaged with nanometer-scale resolution by this AFM technique.