TEMPERATURE-DEPENDENCE OF LEAD LOSS IN RF MAGNETRON SPUTTERING OF A STOICHIOMETRIC PB(ZR,TI)O-3 TARGET

The temperature dependence of lead loss was studied for r.f. magnetron sputtering of a stoichiometric Pb(Zr,Ti)O-3 target (Zr:Ti ratio of 53 :47). Films deposited at 200 degrees C or below crystallized into pero vskite Pb(Zr,Ti)O-3 on receiving an annealing treatment at 600 degrees C or above. No excess lead was used either during sputtering or durin g post-deposition annealing. The Pb(Zr,Ti)O-3 films thus prepared are highly ferroelectric with a maximum polarization of 37 mu C cm(2), a r emanent polarization of 22 mu C cm(-2), and a coercive field of 40 kV cm(-1) measured at 50 Hz. This suggests that lead loss during depositi on is negligible for deposition temperatures of 200 degrees C or below . Films deposited at 500 degrees C were dielectric as-deposited, and b ecame weakly ferroelectric after being annealed at 800 degrees C for 1 h. X-ray spectroscopy analysis of the film indicates significant loss of lead at 500 OC. Depositions at 600 degrees C, however, resulted in thermally stable and dielectric ZrTiO4 films. The structural and diel ectric properties of the films remained unchanged even after annealing at 800 degrees C for 1 h. X-ray spectroscopy analysis indicates that lead was lost completely during sputtering at 600 degrees C. Utilizing this temperature dependence of lead loss to control the composition o f deposited films, a Pb(Zr,Ti)O-3/ZrTiO4 heterostructure was also prep ared successfully from a single oxide target with a two-step, single d eposition process. (C) 1997 Elsevier Science S.A.