Showing papers by "Wolfram Wersing published in 1997"

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

Abstract: 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°C “in situ” growth of tetragonal PZT could be achieved The films exhibited pyroelectric currents without poling The pyroelectric coefficient was 2×10−4 C/m2K, the dielectric constant was 300 and dielectric loss tan δ was 001 The self polarization disappears after heating the sample to 600°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

Pyroelectric devices based on sputtered PZT thin films

Abstract: After a short description of thermal conditions in a pyroelectric sensor, substantial requirements to pyroelectric thin film and sensor design are derived from the theoretical basics. A planar multi-target sputtering process is used to deposit PZT thin films for application in pyroelectric IR sensors. The self-polarized PZT are characterized by a pyroelectric coefficient p of 2-10−4 Cm−2K−1, a dielectric constant [Sgrave] of 300 and a dielectric loss tan δ of 0.01. These material properties, including a low tensile stress of the sensor layer stack of + 110 Mpa, as well as standard microelectronic technologies make the films suitable for the use in pyroelectric sensor arrays. Fabricated singleelement sensors have a specific detectivity D* (500K, 10 Hz) of 3.108 cmHz1/2W−1. An 11×6 array sensor has been developed for motion detection. The array pixels with a sensitive area of 0.0784 mm2 have a noise equivalent power NEP of less than 0.7 nW at 1 Hz.

A 11×6 element pyroelectric detector array utilizing self-polarized pzt thin films grown by sputtering

Abstract: A planar multi target sputtering approach was used to deposit PbTiO3 (PT) and Pb(Zr, Ti)O3 (PZT) films on TiO2/Pt bottom electrodes for the use in thin film pyroelectric IR detector arrays. PZT films with a Zr content of 28 at% (PZ28T) exhibited the best pyroelectric coefficient of typically 2×10−4 Cm−2K−1. The PZ28T films have been used for fabricating a two dimensional 11×6 pixel pyroelectric detector array on Si wafers. The array pixels with a sensitive area of 280 ×280 μm2 have a noise lequivalent power NEP of less than 0.7 nW at 1 Hz. It is planned to use the detector array in systems for motion detection.

Semiconductor detector for infrared radiation and method for manufacturing same

Abstract: A semiconductor detector for infrared radiation is manufactured by the steps of depositing an auxiliary layer on a main surface of a carrier, depositing a membrane layer provided with at least one opening onto the auxiliary layer, selectively etching the auxiliary layer through the at least one opening of the membrane layer, so that a hollow space arises in the auxiliary layer, sealing the hollow space by depositing a covering on th membrane layer, and fashioning a detector element on the covering by depositing a material sensitive to infrared radiation within a region of the covering that is bounded by the hollow space therebelow.