Emission of Negative Copper Cluster Ions as a Function of Temperature and Bombarding Ion Energy

The emission of negative copper cluster ions was studied by secondary ion mass spectrometry as a function of the energy of bombarding cesium and sodium ions and the substrate temperature. The emission of negative cluster ions shows an exponential dependence on the energy of bombarding ions in the threshold emission region, which confirms a recombination mechanism of cluster sputtering. The temperature dependences of the yields of atomic and cluster ions during sputtering of copper by Cs+ ions indicate simultaneous desorption of carbon, oxygen, and copper sulfide species. Prolonged annealing leads to desorption of sulfur oxides and results in vacuum thermal cleaning of the copper surface.