Cubic perovskite Ba(Ti1-xZrx)O-3 (BTZ) thin films of x = 0.12 and 150-180 nm thick were prepared on Pt/Ti/SiO2/Si substrate by rf magnetron sputtering deposition at high temperatures. A satisfactory dielectric constant of 250-305 was obtained for the films deposited at 400 degrees C and 500 degrees C, respectively, but reduced to 210 for that deposited at 600 degrees C. The two films deposited at lower temperatures also had a lower reduction of capacitance against biasing voltage than that at 600 degrees C, and, more importantly, the two exhibited a high and very stable insulating characteristics against biasing. A low leakage current density less than 3 x 10(-9) A/cm(2) was maintained up to a high biasing voltage of 1-2 MV/cm before the onset of an abrupt non-ohmic emission for the two films in a Pt/BTZ/Pt capacitor configuration, and no time-dependent degradation of electric resistance was observed for the two films subjected to a field as high as 2 MV/cm at room temperature. Moreover, a tunneling-like current relation was also found for the non-ohmic current emission in the 500 degrees C-deposited BTZ specimen measured at temperatures ranging from room temperature to 420K. However, the leakage current characteristic of the 600 degrees C-deposited film was greatly degraded.