Low Cost, Contamination-Free, and Damage-Free Fabrication of PZT MEMS on SOI Substrate

2021 ◽  
Author(s):  
Sudhanshu Tiwari ◽  
Randhir Kumar ◽  
Ajay Dangi ◽  
Antony Jeyaseelan A ◽  
Soma Dutta ◽  
...  
Keyword(s):  
Thin Film ◽  
Lead Zirconate Titanate ◽  
Low Cost ◽  
Cost Effective ◽  
Lead Zirconate ◽  
Fabrication Process ◽  
Pzt Thin Film ◽  
Recovery Anneal ◽  
Wet Chemical ◽  
Micro Electromechanical System

Abstract This paper reports a generalised process flow for the fabrication of Lead Zirconate Titanate based Piezoelectric Micro Electromechanical System devices. The optimised process can be used to realise several devices with different 1-D and 2-D geometries on a single wafer. All the state-of-the-art fabrication methods introduce some damage to the active piezoelectric material. This damage entails the need for an additional step of recovery anneal in the fabrication process. Our process was designed and optimised to avoid any such damage to the PZT layer. Remnant polarisation and effective transverse piezoelectric coefficient (e31,f) were used as metrics to quantify the damage to the PZT layer. It is shown that our process does not damage the PZT thin film during the fabrication, and hence no recovery anneal is required. We observe a ~3x improvement in remnant polarisation and ~2x improvement in e31,f of PZT thin film compared to the PZT thin film subjected to our previous fabrication process. Moreover, the process explained here uses only wet chemical methods for patterning of contaminating agents (PZT and platinum), making it a cost-effective process.

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.

scholarly journals Effects of Acetylacetone Additions on PZT Thin Film Processing

1994 ◽  
Vol 361 ◽  
Author(s):  
Robert W. Schwartz ◽  
R.A. Assink ◽  
D. Dimos ◽  
M.B. Sinclair ◽  
T.J. Boyle ◽  
...  
Keyword(s):  
Thin Film ◽  
Lead Zirconate Titanate ◽  
Sol Gel ◽  
Precursor Solution ◽  
Lead Zirconate ◽  
Pzt Thin Film ◽  
Precursor Structure ◽  
Drying Behavior ◽  
Ceramic Microstructure ◽  
Gel Processing

ABSTRACTSol-gel processing methods are frequently used for the fabrication of lead zirconate titanate (PZT) thin films for many electronic applications. Our standard approach for film fabrication utilizes lead acetate and acetic acid modified metal alkoxides of zirconium and titanium in the preparation of our precursor solutions. This report highlights some of our recent results on the effects of the addition of a second chelating ligand, acetylacetone, to this process. We discuss the changes in film drying behavior, densification and ceramic microstructure which accompany acetylacetone additions to the precursor solution and relate the observed variations in processing behavior to differences in chemical precursor structure induced by the acetylacetone ligand. Improvements in thin film microstructure, ferroelectric and optical properties are observed when acetylacetone is added to the precursor solution.

Effects of Added Mass on Lead-Zirconate-Titanate (PZT) Thin-Film Microactuators in Aqueous Environments

2013 ◽  
Author(s):  
Chuan Luo ◽  
Chen-Wei Yang ◽  
G. Z. Cao ◽  
I. Y. Shen
Keyword(s):  
Thin Film ◽  
Lead Zirconate Titanate ◽  
Silicon Substrate ◽  
Laser Doppler Vibrometer ◽  
Lead Zirconate ◽  
Added Mass ◽  
Surrounding Water ◽  
Zirconate Titanate ◽  
Pzt Thin Film ◽  
Aqueous Environments

In this paper, we conduct experimental and theoretical studies of a lead-zirconate-titanate (PZT) thin-film microactuator probe submerged in water. The microactuator consists of a base silicon diaphragm, a layer of bottom electrode, a layer of lead-zirconate-titanate (PZT) thin film, and a layer of top electrode. The diaphragm is anchored on a silicon substrate by etching the silicon substrate from the back to form a cavity under the diaphragm. The diaphragm along with part of its anchor is then diced off from the silicon substrate to form a PZT probe and subsequently packaged with parylene. The probe tip has dimensions of 1 mm × 1 mm × 0.4 mm, while the diaphragm has dimensions of 800 μm × 800 μm × 2 μm. In the experimental study, frequency response functions of actuator displacement are measured via a laser Doppler vibrometer and a spectrum analyzer. The measurements show that the first natural frequency of the microactuator reduces from 80 kHz in air to 20 kHz when the microactuator is submerged in water. A literature search indicates that the surrounding water induces significant added mass to the microactuator. Estimation of the added mass based on theories in fluid mechanics successfully reconcile the predicted frequency to the vicinity of 20 kHz confirming the effects of added mass.

The Role of the Lead Zirconate Titanate (PZT)-Pt Interface in the Anomalous Phase Transformation Kinetics in Sputtered Pzt Thin Film Capacitors at Sub-2000 Å Thicknesses

1991 ◽  
Vol 243 ◽  
Author(s):  
Vinay Chikarmane ◽  
Jiyoung Kim ◽  
C. Sudhama ◽  
Jack Lee ◽  
Al Tasch ◽  
...  
Keyword(s):  
Thin Film ◽  
Phase Transformation ◽  
Lead Zirconate Titanate ◽  
Lead Zirconate ◽  
Initial Increase ◽  
Transformation Kinetics ◽  
Pzt Film ◽  
Zirconate Titanate ◽  
Phase Transformation Kinetics ◽  
Pzt Thin Film

AbstractThe Pt-Lead Zirconate Titanate (PZT) thin film interface plays a key role in determining the electrical properties and phase transformation kinetics of Pt-PZT-Pt thin film capacitor structures. The results of the electrical and material properties of PZT (65/35) films that vary in thickness between 500 Å to 4000 Å deposited by DC-magnetron sputtering under identical deposition conditions, and subjected to the same post-deposition thermal processing conditions shows that the Pt-PZT interface dominates thin film properties at low thicknesses (≦ 2000 Å). The charge storage density (Qc') and maximum polarization (Pmax) shows an anomalous variation with thickness, showing an initial increase followed by a drastic decrease as the film thickness is scaled down to 500Å. Significant interdiffusion at the PZT film-Pt electrode retards the pyrochlore-to-perovskite phase transformation nucleation and growth rate in PZT films of thickness 2000Å and lower. Gate polarity dependence of the time-tobreakdown and the degradation field is observed for all PZT film thicknesses (including 4000Å). This indicates that the ferroelectric film-electrode interface has an important role to play in determining the electrical reliability properties even in the 4000Å thick PZT film, although Qc' and Pmax are not adversely affected at these thicknesses.

Nuclear Reaction Probe of Oxygen Vacancy Migration in Electrically Fatigued PZT Thin Film Capacitors

1994 ◽  
Vol 361 ◽  
Author(s):  
R.L. Pfeffer ◽  
W.D. Wilber
Keyword(s):  
Thin Film ◽  
Lead Zirconate Titanate ◽  
Ferroelectric Thin Film ◽  
Lead Zirconate ◽  
Thin Film Capacitors ◽  
Pzt Thin Film ◽  
Pt Electrodes ◽  
Yttrium Barium Cuprate ◽  
Yttrium Barium ◽  
Accuracy Of Measurement

ABSTRACTThe migration of oxygen vacancies and their entrapment near film-electrode interfaces has been proposed as a cause of fatigue (i.e., polarization weakening) in ferroelectric thin film capacitors. To test this idea, lead zirconate titanate (PZT) thin films were epitaxially deposited by laser ablation on LaAlO3 substrates with yttrium barium cuprate (YBCO) base electrodes. Thin film capacitors were formed by deposition of noble metal (Pt) cap electrodes; half of them were then electrically fatigued by repeated polarization reversals (108 cycles). The distributions of oxygen in the two halves were then compared by means of accelerator-based nuclear backscattering (using the narrow elastic resonance at 3.045 MeV in the scattering of 4He from 16O) throughout the bulk of the PZT films and especially right under the Pt electrodes. We were unable to detect any difference in the oxygen profiles to within the accuracy of measurement, which was about 1 % of the oxygen concentration. Compositional changes, at least involving oxygen, do not seem to be responsible for the striking electrical alterations seen in fatigued PZT.

Improving PZT Thin Film Texture Through Pt Metallization and Seed Layers

2011 ◽  
Vol 1299 ◽  
Author(s):  
L.M. Sanchez ◽  
D.M. Potrepka ◽  
G.R. Fox ◽  
I. Takeuchi ◽  
R.G. Polcawich
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Lead Zirconate Titanate ◽  
Seed Layer ◽  
Film Growth ◽  
Past Research ◽  
Lead Zirconate ◽  
Research Activities ◽  
Pzt Thin Film ◽  
Seed Layers

ABSTRACTLeveraging past research activities in orientation control of lead zirconate titanate (PZT) thin films [1,2], this work attempts to optimize those research results using the fabrication equipment at the U.S. Army Research Laboratory so as to achieve a high degree of {001}- texture and improved piezoelectric properties. Initial experiments examined the influence of Ti/Pt and TiO2/Pt thins films used as the base-electrode for chemical solution deposition PZT thin film growth. In all cases, the starting silicon substrates used a 500 nm thermally grown silicon dioxide. The Pt films were sputter deposited onto highly textured titanium dioxide films grown by a thermal oxidation process of a sputtered Ti film [3]. The second objective targeted was to achieve highly {001}-textured PZT using a seed layer of PbTiO3 (PT). A comparative study was performed between Ti/Pt and TiO2/Pt bottom electrodes. The results indicate that the use of a highly oriented TiO2 led to highly {111}-textured Pt, which in turn improved both the PT and PZT orientations. Both PZT (52/48) and (45/55) thin films with and without PT seed layers were deposited and examined via x-ray diffraction methods (XRD) as a function of annealing temperature. As expected, the PT seed layer provides significant improvement in the PZT {001}-texture while suppressing the {111}-texture of the PZT. Improvements in the Lotgering factor (f) were observed upon comparison of the original Ti/Pt/PZT process (f=0.66) with samples using the PT seed layer as a template, Ti/Pt/PT/PZT (f=0.87), and with films deposited onto the improved Pt electrodes, TiO2/Pt/PT/PZT (f=0.96).

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