INFLUENCES OF ION ENERGY ON MORPHOLOGY AND PREFERRED ORIENTATION OF CHROMIUM THIN-FILMS PREPARED BY ION-BEAM AND VAPOR-DEPOSITION

The influences of ion irradiation on morphologies and preferred orient ations of Cr thin films prepared by ion-beam and vapor deposition were studied. Cr films were prepared onto Si (100) wafers by evaporation o f Cr and simultaneous irradiation with Ar ions. The energies of Ar ion s were changed in the range of 0.5-20.0 keV, and transport ratios of i rradiated Ar ions to vaporized Cr atoms, Ar/Cr, to the substrates were kept at 0.033. Vaporized Cr atoms were deposited onto substrates at a n angle of 45 degrees and Ar ions were irradiated normal to the substr ates. Si substrates were kept at low temperature during deposition. Th e experimental results show that the morphologies and the preferred or ientations were varied due to the change of ion irradiating energy tho ugh other conditions were constant. Every Cr film takes a clear column ar structure. The column widths of Cr films are augmented with increas e of ion energy. The columnar growth direction turns toward the deposi tion direction with increase of ion energy up to 5.0 keV. With further increase of ion energy the direction changes to perpendicular to the substrate, parallel to the direction of the ion irradiation. The prefe rred orientation to the substrate normal changes from random to (100) orientation through (110) and (100) orientation with increasing of ion energy. The reasons were understood as the mixed effects of nuclear a nd electronic energy transfers due to the collisions between Cr atoms and irradiated Ar ions. (C) 1998 American Vacuum Society. [S0734-2101( 98)10304-4].