PZT thin films grown by multi-target sputtering: Analysis of thin film stress

A planar multi target sputtering approach was used to deposit Pb(Zr, Ti)O3 (PZT) films with different composition on Pt bottom electrodes for the use in thin film pyroelectric IR detector arrays. Low stress ferroelectric capacitor stacks are needed in these devices, because the sensing elements are arranged on thin micromachined membranes. PZT films with a Zr content of 10 at% (10/90) and 48 at% (48/52) were analyzed in terms of thin film stress. PZT (10/90) films were found in a slight compressed state and PZT (48/52) under tensile stress after deposition. Stress temperature curves were used to evaluate the Curie temperature of the films. From the stress temperature curves the spontaneous distortion of the ferroelectric given by the lattice parameters can be extracted. The lower Curie temperature in combination with the smaller spontaneous distortion of the PZT (48/52) film is the reason for the difference in the stress state after deposition.