A COMPLETE CHARACTERIZATION OF CA-5(PO4)(3)OH SPUTTER-DEPOSITED FILMSBY ION-BEAM ANALYSIS - RBS AND ERD

RF magnetron sputter deposition was used to deposit thin calcium phosp hate (hydroxyapatite) lavers on titanium alloy substrate material. We determined the precise amount of calcium, phosphorus, oxygen, and hydr ogen in these films by combining two ion-beam analysis techniques: Rut herford backscattering spectrometry (RBS) and elastic recoil detection (ERD). Variables were Fewer level partial oxygen pressure, or additio nal water vapor. Also examined was the influence of additional bias po wer to the substrates during deposition and the effect of annealing on the final composition of the deposited layers. Measurements showed th at the Ca/P ratio decreased with increasing oxygen pressure or decreas ing sputtering Fewer. Ln addition, the Ca/P ratio increased when a bia s was applied to the substrates. The O/P ratio of the films decreased with additional oxygen pressure but increased when additional water va por was applied during deposition. AU as-deposited films showed a high er hydrogen content than stoichiometric HA. The hydrogen content in th e films deposited with water vapor was more than 7 times higher than i n the films deposited under pure argon conditions. After annealing, th e hydrogen content decreased to about 3.5 at % whereas in stoichiometr ic HA the hydrogen content amounts to 4.5 at %. After annealing, the o xygen concentration in the film also decreased. We assume that hydroge n disappears out of the film as H2O during annealing. For the targets used in these experiments, sputter deposition at 400 W, with additiona l water vapor and annealing at 500 degrees C, produced films with a st oichiometry closest to that of hydroxyapatite. (C) 1998 John Wiley & S ons, Inc.