Deposition of self-polarized PZT films by planar multi-target sputtering

A planar multi target sputtering approach was used to deposit self polarized PZT films on TiO2/Pt bottom electrodes for the use in thin film pyroelectric IR detector arrays. By using elevated substrate temperatures of about 450 degrees C ''in situ'' growth of tetragonal PZT could be achieved. The films exhibited pyroelectric currents without poling. The pyroelectric coefficient was 2 x 10(-4) C/m(2)K, the dielectric constant was 300 and dielectric loss tan delta was 0.01. The self polarization disappears after heating the sample to 600 degrees C. Stresses were studied in the thin film processing for the bottom electrode and the PZT film. The TiO2/Pt electrode is under high tensile stress of 900 MPa after preparation. PZT has a small compressive stress of -60 MPa, the whole TiO2/Pt/PZT stack has a tensile stress of +80 MPa. This low stress level together with the self polarization and the good electrical properties makes the films suitable for the use in pyroelectric detector arrays.