Surface processing by gas cluster ion beams

Clusters consisting of hundreds to thousands of weakly bound atoms or molecules can be formed from various gases by expanding the gas through a small nozzle into high vacuum. Gas clusters can be ionized and subjected to acceleration potentials so as to produce beams of cluster ions which possess high total energy, mass and momentum in combination with low energy per constituent atom. Gas cluster ion beams have been shown to be capable of producing processing effects which have not been available with monomer ions, A number of prospective applications for gas cluster ions have been identified and commercial gas cluster ion beam equipment is now being developed, This paper reviews the status of gas cluster ion technology and includes discussion of methods for generation of the gas cluster beams, kinetics of the interactions of cluster ions with solid materials and anticipated applications.