Walter Hartner

Influence of Ti-content in the bottom electrodes on the ferroelectric properties of SrBi2Ta2O9 (SBT)

Abstract Stress behavior, results of AES analysis and electrical properties of SBT in dependence of electrode structure and annealing conditions are discussed. Evidence for degradation of the electrical properties of SBT due to diffusion of Ti is presented.

Imprint in ferroelectric SrBi2Ta2O9 capacitors for non-volatile memory applications

Abstract Imprint is known as a failure mechanism in ferroelectric capacitors due to a voltage shift in the hysteresis curve. A detailed study to investigate the time, temperature and bias voltage dependence of the voltage shift was performed on MOD SBT thin films. Lifetime extrapolation under operating conditions (125 °C) reveal values for the lifetime of well over ten years.

Influence of dry etching using argon on structural and electrical properties of crystalline and non-crystalline SrBi2Ta2O9 thin films

Abstract After patterning the Platinum/crystalline SrBi2Ta2O9 bilayer by Argon based Reactive Ion Etching (RIE), a degradation of the remanent polarization and leakage current of the capacitors for smaller feature sizes is observed. To simulate the study of the side wall of the capacitors, etching of blanket SBT is used as a model experiment. It is shown that etching of crystalline SBT is damaging the SBT material, resulting in the formation of small crystallites (SEM), the appearance of an unknown peak (XRD) and reduction of the Bismuth content on the SBT surface (AES). Using non-crystalline SBT, neither a degradation of electrical properties for smaller feature sizes nor a structural damage of blanket SBT is found after etching and recrystallization annealing although after etching of non-crystalline SBT also a loss of Bi is seen as indicated by AES. Therefore the following model is proposed: Patterning the Pt/crystalline SBT capacitor leads to a Bi deficient edge of the dielectric. Due to the crystalli...