Electrical Properties of PZT Thin Film Capacitors with Novel Pt-Ir Based Electrode Barriers for Nonvolatile Memories

1998 ◽  
Vol 541 ◽  
Author(s):  
Chandra S. Desu ◽  
Ramakrishna Vedula ◽  
Kwang B. Lee ◽  
Seshu B. Desu
Keyword(s):  
Thin Film ◽  
Electrical Properties ◽  
Noble Metals ◽  
Hysteresis Loops ◽  
Barrier Structure ◽  
Leakage Currents ◽  
Ferroelectric Capacitor ◽  
Nonvolatile Memories ◽  
Thin Film Capacitors ◽  
Pzt Thin Film

AbstractA new electrode barrier structure based on noble metals Pt and Ir alloys and their oxides was proposed for the integration of PZT capacitors into high density nonvolatile memories. The proposed PtIrOx/PtIr/PtIrOx structure with Pt rich compositions (∼90%) is an excellent conducting electrode for the ferroelectric capacitor and a very good diffusion barrier for species like oxygen and Si. These structures are thermally stable up to the PZT processing temperatures of 650°C. PZT deposited on these electrodes crystallized predominantly in pervoskite phase. The test capacitors showed well saturated hysteresis loops with Pr and Ec of 21.3 µC/cm2 and 43 kV/cm, respectively. An extremely low polarization fatigue of 3% after 1× 1011 repetitions and leakage currents close to those on Pt were observed.

Contribution of electrodes and microstructures to the electrical properties of Pb(Zr0.53Ti0.47)O3 thin film capacitors

1994 ◽  
Vol 9 (11) ◽  
pp. 2968-2975 ◽  
Author(s):  
H.N. Al-Shareef ◽  
A.I. Kingon ◽  
X. Chen ◽  
K.R. Bellur ◽  
O. Auciello
Keyword(s):  
Thin Film ◽  
Electrode Material ◽  
Bottom Electrode ◽  
Low Voltage ◽  
Order Effect ◽  
Major Effect ◽  
Leakage Currents ◽  
Ohmic Behavior ◽  
Thin Film Capacitors ◽  
Pzt Thin Film

Pb(Zr0.53Ti0.47)O3 (PZT) thin film capacitors have been fabricated with four electrode combinations: Pt/PZT/Pt/SiO2Si, RuO2/PZT/Pt/SiO2/Si, RuO2/PZT/RuO2/SiO2/Si, and Pt/PZT/RuO2/SiO2/Si. It is shown that polarization fatigue is determined largely by the electrode type (Pt vs RuO2), and microstructure has only a second-order effect on fatigue. If either the top or bottom electrode is platinum, significant polarization fatigue occurs. Fatigue-free capacitors are obtained only when both electrodes are RuO2. In contrast, the bottom electrode is found to have a major effect on the leakage characteristics of the PZT capacitors, presumably via microstructural modifications. Capacitors with bottom RuO2 electrodes show high leakage currents (J = 10−3-10−5 A/cm2 at 1 V) irrespective of the top electrode material. Capacitors with Pt bottom electrodes have much lower leakage currents (J = 10−8 A/cm2 at 1 V) irrespective of the top electrode material. At low voltage, the I-V curves show ohmic behavior and negligible polarity dependence for all capacitor types. At higher voltages, the leakage current is probably Schottky emission controlled for the capacitors with Pt bottom electrodes.

Correlations Among Degradations in Lead Zirconate Titanate thin Film Capacitors

1993 ◽  
Vol 310 ◽  
Author(s):  
In K. Yoo ◽  
Seshu B. Desu ◽  
Jimmy Xing
Keyword(s):  
Thin Film ◽  
Leakage Current ◽  
Lead Zirconate Titanate ◽  
Oxygen Vacancies ◽  
Lead Zirconate ◽  
Electrical Degradation ◽  
Zirconate Titanate ◽  
Thin Film Capacitors ◽  
Pzt Thin Film ◽  
Degradation Properties

AbstractMany attempts have been made to reduce degradation properties of Lead Zirconate Titanate (PZT) thin film capacitors. Although each degradation property has been studied extensively for the sake of material improvement, it is desired that they be understood in a unified manner in order to reduce degradation properties simultaneously. This can be achieved if a common source(s) of degradations is identified and controlled. In the past it was noticed that oxygen vacancies play a key role in fatigue, leakage current, and electrical degradation/breakdown of PZT films. It is now known that space charges (oxygen vacancies, mainly) affect ageing, too. Therefore, a quantitative ageing mechanism is proposed based on oxygen vacancy migration under internal field generated by either remanent polarization or spontaneous polarization. Fatigue, leakage current, electrical degradation, and polarization reversal mechanisms are correlated with the ageing mechanism in order to establish guidelines for simultaneous degradation control of PZT thin film capacitors. In addition, the current pitfalls in the ferroelectric test circuit is discussed, which may cause false retention, imprint, and ageing.

Characterisation of the fatigued state of ferroelectric PZT thin-film capacitors

1995 ◽  
Vol 29 (1-4) ◽  
pp. 145-148 ◽  
Author(s):  
E.L. Colla ◽  
A.L. Kholkin ◽  
D. Taylor ◽  
A.K. Tagantsev ◽  
K.G. Brooks ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Film Capacitors ◽  
Pzt Thin Film

scholarly journals Synchrotron X-ray Microdiffraction Images of Polarization Switching in Epitaxial PZT Capacitors with Pt and SrRuO3 Top Electrodes

2003 ◽  
Vol 784 ◽  
Author(s):  
Dal-Hyun Do ◽  
Dong Min Kim ◽  
Chang-Beom Eom ◽  
Eric M. Dufresne ◽  
Eric D. Isaacs ◽  
...  
Keyword(s):  
Thin Film ◽  
Bottom Electrode ◽  
Sputter Deposition ◽  
Ferroelectric Polarization ◽  
X Rays ◽  
X Ray ◽  
Pzt Film ◽  
Thin Film Capacitors ◽  
Pzt Thin Film ◽  
Switchable Polarization

ABSTRACTThe evolution of stored ferroelectric polarization in PZT thin film capacitors was imaged using synchrotron x-ray microdiffraction with a submicron-diameter focused incident x-ray beam. To form the capacitors, an epitaxial Pb(Zr,Ti)O3 (PZT) thin film was deposited on an epitaxially-grown conductive SrRuO3 (SRO) bottom electrode on a SrTiO3 (STO) (001) substrate. Polycrystalline SRO or Pt top electrodes were prepared by sputter deposition through a shadow mask and subsequent annealing. The intensity of x-ray reflections from the PZT film depended on the local ferroelectric polarization. With 10 keV x-rays, regions of opposite polarization differed in intensity by 26% in our PZT capacitor with an SRO top electrode. Devices with SRO electrodes showed just a 25% decrease in the remnant polarization after 107 switching cycles. In devices with Pt top electrodes, however, the switchable polarization decreased a by 70% after only 5×104 cycles.

Breakdown mechanisms in PZT thin film capacitors

1995 ◽  
Vol 11 (1-4) ◽  
pp. 269-275 ◽  
Author(s):  
In Kyeong Yoo ◽  
Chang Jung Kim ◽  
Seshu B. Desu
Keyword(s):  
Thin Film ◽  
Thin Film Capacitors ◽  
Pzt Thin Film

Electrical Properties of Lead Lanthanum Titanate Thin-Film Capacitors Prepared by Sol-Gel Method

1995 ◽  
Vol 34 (Part 1, No. 11) ◽  
pp. 6133-6138 ◽  
Author(s):  
Su Jae Lee ◽  
Min Su Jang ◽  
Chae Ryong Cho ◽  
Kwang Yong Kang ◽  
SeokKilHan
Keyword(s):  
Thin Film ◽  
Electrical Properties ◽  
Sol Gel ◽  
Gel Method ◽  
Sol Gel Method ◽  
Thin Film Capacitors ◽  
Lanthanum Titanate ◽  
Titanate Thin Film
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