Sputtering of self-polarized PZT films for IR-detector arrays

Within a 3-year project a pyroelectric detector array based on a tetragonal Pb(Zr,Ti)O/sub 3/ (PZT) thin film on a silicon substrate was developed. Compositions of about 25-30% Zr showed best properties for the application in pyroelectric sensing systems. For the film deposition, planar multi target sputtering from 3 metallic targets in a reactive Ar/O/sub 2/ mixture is used. The advantage of this method is that the perovskite phase can be grown down to relatively low substrate temperatures of about 500/spl deg/C, a strong self polarization for compositions Zr/(Zr+Ti)<0.3 and a convenient control of the stoichiometry simply by varying the power supplied to the individual targets. The developed chip has (11/spl times/6) elements, his overall size is (8/spl times/4,7) mm/sup 2/. The array pixels of 280/spl times/280 /spl mu/m/sup 2/ have a noise equivalent power NEP of less than 0.7 nW at 1 Hz. The achieved specific detectivity D/sup */ at a modulation frequency of 10 Hz is 3/spl middot/10/sup 8/ cm/spl middot/Hz/sup 1/2//W.