SIMS depth profile study using metal cluster complex ion bombardment

SIMS depth profiles using a metal cluster complex ion of Ir4(CO)7+ were studied. An unusual increase of the sputtering yield under the condition of small incident angle may be attributed to the suppression of taking oxygen from flooding O2 by the formation of a carbon cover-layer derived from Ir4(CO)7+ ion. Even though the roughness of the sputtered surface is small, the depth resolution was not improved by decreasing the cluster ion energy to less than 5 keV, because the carbon cover-layer prevents the formation of surface oxide that buffers atomic mixing. To overcome this issue, it will be necessary to eliminate carbon from the cluster ion.