Ferroelectric Dielectrics Integrated on Silicon E-Book

• Herausgeber: John Wiley & Sons
• Kategorie: Wissenschaft und neue Technologien
• Sprache: Englisch

Seitenzahl: 679

Veröffentlichungsjahr: 2013

Beschreibung

This book describes up-to-date technology applied to high-K materials for More Than Moore applications, i.e. microsystems applied to microelectronics core technologies. After detailing the basic thermodynamic theory applied to high-K dielectrics thin films including extrinsic effects, this book emphasizes the specificity of thin films. Deposition and patterning technologies are then presented. A whole chapter is dedicated to the major role played in the field by X-Ray Diffraction characterization, and other characterization techniques are also described such as Radio frequency characterization. An in-depth study of the influence of leakage currents is performed together with reliability discussion. Three applicative chapters cover integrated capacitors, variables capacitors and ferroelectric memories. The final chapter deals with a reasonably new research field, multiferroic thin films.

Leseprobe

Table of Contents

Preface

Chapter 1. The Thermodynamic Approach

1.1. Background

1.2. The functions of state

1.3. Linear equations, piezoelectricity

1.4. Nonlinear equations, electrostriction

1.5. Thermodynamic modeling of the ferroelectric–paraelectric phase transition

1.6. Conclusion

1.7. Bibliography

Chapter 2. Stress Effect on Thin Films

2.1. Introduction

2.2. Modeling the system under consideration

2.3. Temperature–misfit strain phase diagrams for monodomain films

2.4. Domain stability map

2.5. Temperature–misfit strain phase diagram for polydomain films

2.6. Discussion of the nature of the “misfit strain”

2.7. Conclusion

2.8. Experimental validation of phase diagrams: state of the art

2.9. Case study

2.10. Results

2.11. Comparison between the experimental data and the temperature–misfit strain phase diagrams

2.12. Conclusion

2.13. Bibliography

Chapter 3. Deposition and Patterning Technologies

3.1. Deposition method

3.2. Etching

3.3. Contamination

3.4. Monocrystalline thin-film transfer

3.5. Design of experiments

3.6. Conclusion

3.7. Bibliography

Chapter 4. Analysis Through X-ray Diffraction of Polycrystalline Thin Films

4.1. Introduction

4.2. Some reminders of x-ray diffraction and crystallography

4.3. Application to powder or polycrystalline thin-films

4.4. Phase analysis by X-ray diffraction

4.5. Identification of coherent domain sizes of diffraction and micro-strains

4.6. Identification of crystallographic textures by X-ray diffraction

4.7. Determination of strains/stresses by X-ray diffraction

4.8. Bibliography

Chapter 5. Physicochemical and Electrical Characterization

5.1. Introduction

5.2. Useful characterization techniques

5.3. Ferroelectric measurement

5.4. Dielectric measurement

5.5. Bibliography

Chapter 6. Radio-Frequency Characterization

6.1. Introduction

6.2. Notions and basic concepts associated with HF

6.3. Frequency analysis: HF characterization of materials

6.4. Bibliography

Chapter 7. Leakage Currents in PZT Capacitors

7.1. Introduction

7.2. Leakage current in metal/insulator/metal structures

7.3. Problem of leakage current measurement

7.4. Characterization of the relaxation current

7.5. Literature review of true leakage current in PZT

7.6. Dynamic characterization of true leakage current: I(t, T)

7.7. Static characterization of the true leakage current: I(V, T)

7.8. Conclusion

7.9. Bibliography

Chapter 8. Integrated Capacitors

8.1. Introduction

8.2. Potentiality of perovskites for RF devices: permittivity and losses

8.3. Bi-dielectric capacitors with high linearity

8.4. STO capacitors integrated on CMOS substrate by AIC technology

8.5. Bibliography

Chapter 9. Reliability of PZT Capacitors

9.1. Introduction

9.2. Accelerated aging of metal/insulator/metal structures

9.3. Accelerated aging of PZT capacitors through CVS tests

9.4. Lifetime extrapolation of PZT capacitors

9.5. Conclusion

9.6. Bibliography

Chapter 10. Ferroelectric Tunable Capacitors

10.1. Introduction

10.2. Overview of the tunable capacitors

10.3. Types of actual tunable capacitors

10.4. Toward new tunable capacitors

10.5. Bibliography

Chapter 11. FRAM Ferroelectric Memories: Basic Operations, Limitations, Innovations and Applications

11.1. Taxonomy of non-volatile memories

11.2. FRAM memories: basic operations and limitations

11.3. Technologies available in 2011

11.4. Technological innovations

11.5. Some application areas of FRAM technology

11.6. Conclusion

11.7. Bibliography

Chapter 12. Integration of Multiferroic BiFeO3 Thin Films into Modern Microelectronics

12.1. Introduction

12.2. Preparation methods

12.3. Ferroelectricity and magnetism

12.4. Device applications

12.5. Bibliography

First published 2011 in Great Britain and the United States by ISTE Ltd and John Wiley & Sons, Inc. Adapted and updated from Diélectriques ferroélectriques intégrés sur silicium published 2011 in France by Hermes Science/Lavoisier © LAVOISIER 2011

Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the Copyright, Designs and Patents Act 1988, this publication may only be reproduced, stored or transmitted, in any form or by any means, with the prior permission in writing of the publishers, or in the case of reprographic reproduction in accordance with the terms and licenses issued by the CLA. Enquiries concerning reproduction outside these terms should be sent to the publishers at the undermentioned address:

ISTE Ltd 27-37 St George's Road London SW19 4EU UKwww.iste.co.uk

John Wiley & Sons, Inc. 111 River Street Hoboken, NJ 07030 USAwww.wiley.com

© ISTE Ltd 2011

The rights of Emmanuel Defaÿ to be identified as the authors of this work have been asserted by him in accordance with the Copyright, Designs and Patents Act 1988.

Library of Congress Cataloging-in-Publication Data

Ferroelectric dielectrics integrated on silicon / edited by Emmanuel Defaÿ.     p. cm.   Adapted and updated from: Dielectriques ferroelectriques integres sur silicium, published in France by Hermes Science/Lavoisier, 2011.   Includes bibliographical references and index.   ISBN 978-1-84821-313-5   1. Ferroelectric thin films. 2. Silicon--Electric properties. 3. Electric batteries--Corrosion. I. Defaÿ, Emmanuel.   QC596.5.F44 2011   621.3815'2--dc23

2011035048

British Library Cataloguing-in-Publication Data

Preface

The idea of this book germinated in 2008 following a discussion with Michel Bruel about the work on materials of the perovskite family carried out at CEA LETI Minatec in Grenoble. It quickly came to our mind to bring together in one document the studies that we have undertaken in this area since the early 2000s. Thus several people have come to lend a hand in the writing of this book by taking charge of a section or a chapter corresponding to their area of expertise. Twenty-one people have contributed to this project, which was eventually split into two volumes: the first, Piezoelectric Materials Integrated on Silicon, published by ISTE in 2011 and dedicated to the study of thin piezoelectric films and the second volume on dielectrics with very high permittivity and ferroelectrics.

In this book, following the same vein as the piezoelectricity book, I wanted to repeat the basic thermodynamic concepts in order to lay down a solid foundation. However, it will be noted that this book is much more focused on technological aspects with nine chapters on this thematic out of twelve in total. Chapter 1 is dedicated to the general theory of thermodynamics, which works very well to explain most of the properties of these materials. Chapter 2 deals with the specific property of thin films on a substrate and the radical change that it induces on the mathematical formulation of this subject. Chapter 3 covers the techniques of deposition and shaping of these specific dielectric layers. Chapter 4 is exclusively dedicated to X-ray diffraction techniques that are fundamental to gauge the structural properties of these layers. Chapter 5 is a more general approach to the physicochemical characterization usually associated with these layers. Chapter 6 tackles a completely different field yet fundamental to the radio-frequency applications of these layers: the radio-frequency characterization. Chapter 7 is an embodiment of high permittivity capacitors of Pb(Zr,Ti)O3 and includes an in-depth treatment of the leakage currents of these materials in thin films. Chapter 8 presents several examples of capacitors integrated on silicon. Chapter 9 deals with the reliability of these high permittivity capacitors, a field that is not often addressed and yet one that is crucial for the integration. Chapter 10 covers the field of tunable ferroelectric capacitors and Chapter 11 describes the implementation of ferroelectric memories.

To complete, I would like to thank those who participated in the elaboration of this book. I would start by Michel Bruel, an emblematic figure of LETI, and Marc Aïd, head of the radio frequencies components laboratory, who have been a constant support throughout these years of work. Then I want to thank Pierre Eymeric Janolin of Ecole Centrale de Paris, who agreed to work on Chapter 2 relating to the influence of substrate on thin films, Chrystel Deguet, who worked on layers transfer (Chapter 3), Bertrand Vilquin, who described the Molecular Beam Epitaxy (MBE) technique (Chapter 3), Gwenael Le Rhun, one of my closest colleagues who greatly contributed to Chapter 3 and almost exclusively to Chapter 5 on the techniques for physicochemical characterization, Patrice Gergaud, who took charge of Chapter 4 on X-ray diffraction, Brahim Dkhil and Pascale Gemeiner, who described the Raman technique in Chapter 5, and Thierry Lacrevaz, who took charge of Chapter 6 on radio-frequency characterization. A special mention goes to Emilien Bouyssou, who wrote all of Chapters 7 and 9 on leakage currents and the reliability of PZT capacitors in thin films, Benoit Guigues, who wrote the overwhelming majority of Chapter 10 in its, and Christopher Muller, who took charge of Chapter 11 on ferroelectric memories. I would finally like to thank Xiaohong Zhu, who wrote the last chapter on multiferroic materials.

Finally, my thoughts go to my wife and two daughters for their everlasting support.

Emmanuel DEFAŸ September 2011

Chapter 1The Thermodynamic Approach1

1.1. Background

Despite several decades of studying microscopic modeling, no theory is yet reliable enough to explain and fully predict the behavior of perovskite in thin films although the ab initio or “from first principle” approach is beginning to give very good results [JUN 03].

However, the phenomenological approach based on thermodynamics, which is a statistical view of the problem, helps to explain a very large proportion of the numerous behaviors of perovskites. Although the case of thin films is more delicate due to extrinsic effects such as residual stresses, interfaces, composition inhomogeneities, lattice, or domain wall motion effects, it is often possible to understand, at least qualitatively, how a device that integrates a perovskite material will behave by using the thermodynamic formalism.

Therefore, in this chapter, we develop the equations that enable us to use this formalism. This energetic method is very useful to understand the several possible couplings that arise in perovskites. The general idea is to have the most general description of the system energy and, therefore, to quantify the conversions of the thermal, mechanical, electrostatic, or magnetic energies.

This theory is often referred to as Landau Ginzburg Devonshire (LGD), all three having sequentially contributed to developing it in the first half of the 20th Century. Landau’s work focused on second-order phase transitions, which are those that do not involve the latent heat of transition. This may be a ferromagnetic or ferroelectric near the Curie temperature, a superconducting material near its transition phase or a fluid near its critical point. All these transitions may behave with many similarities (“universality” concept) and are called “critical phenomena” in the literature, widely studied since the pioneering work of Landau [LIN 77]. In 1950, Landau and Ginzburg adjusted the original Landau theory to the study of transition of a superconductor. In 1949, Devonshire was inspired by this formalism to apply it to the study of ferroelectrics [DEV 49]. This global energetic approach has been a great success and is still used today, especially for thin films. It is thus possible to take into account domain walls, stresses due to the substrate and many couplings.

In this approach, the concept of symmetry is important because there is a loss of symmetry during phase transition (liquid solid, ferromagnetic paramagnetic, and ferroelectric paraelectric) nearly all the time. It is essential to be able to quantify the change in symmetry induced during transition by a parameter that characterizes the system and is called the order parameter.

Thus, in our case, it is the polarization that represents the order parameter to describe the transition between the paraelectric and ferroelectric states. Landau assumes that the free energy of the system undergoing transition can be described by an analytic function of the order parameter and precisely by an expansion in even powers of the latter. For ferroelectrics, this assumption means that the energy of the higher symmetry phase is the same whatever the sign of the applied field associated with the order parameter. This is the case because polarization is always aligned to the applied electric field in the paraelectric phase and thus the electrostatic contribution to the energy is the same irrespective of the field sign. Phase transition is also characterized by a transition temperature. The latter was introduced by Landau in his formalism so that the order parameter is zero in the high-temperature phase of high symmetry and non-zero in the low-temperature phase of lower symmetry.

We elaborate on this account by addressing thermodynamic formalism in Section 1.2.

1.2. The functions of state

This formalism has been widely described in the literature. It is repeated here to bring together the various approaches that have been proposed and to ensure consistency in the notations that we have come across. This section is largely inspired by the articles of Devonshire [DEV 49], Damjanovic [DAM 98], as well as the bookby Lines and Glass [LIN 77].

The fact that several energetic couplings are possible in many cases induces the mixing of several physical domains without a priori there being any link in the development of their respective models. In thermodynamics, such as we might have seen, the microscopic state of a system is described by the decomposition of its internal energy into several distinct contributions: mechanical, electrical, thermal, magnetic, and chemical. All these contributions correspond to global and statistical values, regardless of any microscopic description of the state of the matter in the considered system. If we are able to write the expression of this internal energy, then we can determine the state of the system based on independent macroscopic variables (for instance, the pressure or the electric field) and it becomes possible to determine its equilibrium as a function of these variables.

In the expression of internal energy, the infinitesimal amount of work δW depends on the nature of the system interactions with the external environment. Here, we consider two types of work interactions that may apply to the considered solids: mechanical and electrical. The generalization to other forms of energy (especially magnetic) may be done in the same way. The so-called conjugate pairs of variables to be considered are stresses S and strains T for the mechanical part and electric field E and electric displacement D for electrical components. The heat contribution is described by entropy σ and temperature θ as usual.

Thus, for these two types of work, by using the first principle in the case of a quasi-static transformation, the infinitesimal variation of internal energy is the sum of the infinitesimal variations of heat () and works (we can note that “” is used for heat and work as their variations are generally not differentials):