Materials Processing by Cluster Ion Beams

146 Materials Processing by Cluster Ion Beams

The surfaces were examined by AFM. The scan area of the

AFM was either 1 × 1 μm or 10 × 10 μm. Figure6.11 shows

the AFM images of the Cu surfaces. The initial Cu surface

(Figure6.11a) had many grains typically about 400 nm wide

and 15 nm in height, and the average roughness was 5.8 nm.

Following Ar monomer ion bombardment (Figure6.11b), there

were still many grains on the surface, and small hillocks

caused by the energetic ion bombardment were observed. The

average roughness of this surface was 4.9 nm, which means

that the surface roughness was only slightly improved by the

20keV Ar monomer ions at normal incidence.

When the Cu target was irradiated by an Ar cluster ion

beam (Figure 6.11c)