Study On The Preparation Of Sputtered PZT Films Induced By Buffer Layer

During the recent years,PZT films with preferred orientation have been widely applied in energy collector,infrared sensor,ferroelectric memory and inkjet printing head.In this paper,PZT thin films were prepared on the sol-gel buffer layer by magnetron sputtering.It mainly includes the following contents:(1)The preparation process of PZT ceramic targets were studied.In this paper,PZT ceramic targets with different components were prepared by solid-state sintering method.The technological parameters were:The milling speed was 300 r/min,the milling time was 24 h;The pre sintering temperature was 850?,the holding time was 2 h;The sintering temperature was kept at 1050?,the holding time was 2.5 h.the PZT thin films obtained by sputtering method with self-made target showed(111)preferred orientation and completely perovskite structure.(2)The effect of the variation of Zr/Ti ratio of buffer layers on the properties of PZT thin films was researched.First,the sol-gel buffer layers Pb_1.10(Zr_x,Ti_1-x)O₃(x=0.25,0.35,0.45,0.55,0.65,0.75)were prepared,and Pb_1.10(Zr_0.52,Ti_0.48)O₃ thin films were deposited on the buffer layer by magnetron sputtering.The result of testing shown:The increase of Zr/Ti of buffer layer makes the crystallization of the thin films more difficult;When x=0.75,pyrochlore phase appeared in the thin films;When x=0.65,PZT thin film exhibited strong(111)peak and the best crystallization quality,with the largest average grain size of 200.7 nm;While x=0.65,the maximum dielectric constant,?_r=959.5 and the best ferroelectric properties,P_r=17.0?C/cm²,E_c=42.9 k V/cm are obtained.(3)Double layer buffer layers consist of Pb_1.10(Zr_1-x,Ti_x)O₃/Pb_1.10(Zr_x,Ti_1-x)O₃(x=0.25,0.35,0.45)and Pb_1.10(Zr_0.52,Ti_0.48)O₃(Zr/Ti,52/48)were introduced,and PZT thin films were deposited on the buffer layer by sputtering to study the effect of composition of Zr/Ti complementary buffer layers on the properties of PZT thin films.When x=0.45,the samples have the highest(100)preferred orientation,?(100)=89.1%;When x=0.45,PZT thin film exhibited dense columnar structure,the best dielectric properties?_r=1262.17(1 k Hz)and ferroelectric properties(P_r=24.7?C/cm²).Sample x=0.45 film showed the smallest leakage current density,J=3.15×10^-6 A/cm²(141 k V),which is about 1/2 of the leakage current density of sample 52/48(6.16×10^-6 A/cm²).(4)The influence of the number of layers of PZT films with different Pb content on the properties of the films was studied.Ferroelectric multilayer PZT thin films composed of Pb_1.10(Zr_0.52,Ti_0.48)O₃ and Pb_1.25(Zr_0.52,Ti_0.48)O₃were prepared on Pb_1.10(Zr_0.52,Ti_0.48)O₃ buffer layers with RF magnetron sputtering method.All films showed single perovskite phase and(111)preferred orientation.The best dielectric properties were obtained in L-8 film,?_r=1092(1 kHz).The sample L-8 exhibited saturated P-E hysteresis curve.The minimum leakage current density of J=5.49×10^-6 A/cm² at 117 k V electric field was measured in L-8 film.(5)Piezoelectric coefficient of PZT film was measured,piezoelectric microactuator was prepared and characterized.The transverse piezoelectric coefficient e₃₁ of PZT thin films with Pb_1.10(Zr_1-x,Ti_x)O₃/Pb_1.10(Zr_x,Ti_1-x)O₃ buffer layers were measured by cantilever method;The piezoelectric micro actuator were fabricated by MEMS technology,and the amplitudes of the microactuators were characterized by laser Doppler system.The sample x=0.45 exhibited the maximum piezoelectric coefficient and amplitude.