David Novosel

G. Campardo · R. Micheloni · D. Novosel VLSI-Design of Non-Volatile Memories Giovanni Campardo · Rino Micheloni · David Novosel VLSI-Design of Non-Volatile Memories With 568 Figures Giovanni Campardo Rino Micheloni STMicroelectronics Srl Memory Product Groups Flash Division Via C. Olivetti 2 20041 Agrate Brianza (MI) Italy David Novosel IMD Intelligent Micro Design, Inc. Mercer-West Middlesex Road 2456 West Middlesex, PA 16159 U.S.A. ISBN 3-540-20198-X Springer Berlin Heidelberg New York Library of Congress Control Number: 2004116726 This work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilm or in other ways, and storage in data banks.Duplicationofthispublicationorpartsthereofispermittedonlyundertheprovisions of the German Copyright Law of September 9, 1965, in its current version, and permission for use must always be obtained from Springer-Verlag. Violations are liable to prosecution under German Copyright Law. SpringerisapartofSpringerScience+Business Media springeronline.com c Springer-Verlag Berlin Heidelberg 2005 Printed in Germany The use of general descriptive names, registered names, trademarks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. Typesetting: Data conversion by the author. Final processing by PTP-Berlin Protago-TEX-Production GmbH, Germany Cover-Design: medionet AG, Berlin Printed on acid-free paper 62/3141/Yu-543210 Preface The electronics and information technology revolution continues, but it is a critical time in the development of technology. Once again, we stand on the brink of a new era where emerging research will yield exciting applications and products destined to transform and enrich our daily lives! The potential is staggering and the ultimate impact is unimaginable, considering the continuing marriage of technology with fields such as medicine, communications and entertainment, to name only a few. But who will actually be responsible for transforming these potential new products into reality? The answer, of course, is today’s (and tomorrow’s) design engineers! The design of integrated circuits today remains an essential discipline in sup- port of technological progress, and the authors of this book have taken a giant step forward in the development of a practice-oriented treatise for design engineers who are interested in the practical, industry-driven world of integrated circuit design. The authors, Giovanni Campardo and Rino Micheloni, are very well qualified to effectively address this challenging objective. Both have a solid track record of leading design activities at the STMicroelectronics Flash Division. I should probably mention at this point my association with and knowledge of the accom- plishments of these authors. In April 2003, they published a unique Special Issue on the subject of Flash Memories for the Proceedings of the IEEE, the journal for which I am Managing Editor. Therefore, I have firsthand knowledge of their approach to the development of very well crafted technical material. In addition, a third member of the author team, David Novosel, has provided invaluable assistance, particularly in the translation efforts on this material. David is President and founder of Intelligent Micro Design, Inc. which specializes in the design of custom memories and analog circuits, which is located in Pitts- burgh, PA. This book is intended for Electrical Engineering graduates who want to enter into the integrated circuit design world. Nonvolatile memories, in many cases, are treated as an example to explain general design concepts (basic circuits, layout, design flow, etc.). Practical illustrative examples of nonvolatile memories, includ- ing flash types, are showcased to give insightful examples of the design ap- proaches that are discussed. The authors introduce the key nonvolatile memories design issues in the first section and they discuss the various functions and capa- bilities of these memories; much of these discussions are based on their recently published Special Issue on the subject of Flash memories. VI Preface After a complete review of the general design issues, the authors begin to focus on the important concepts that should be understood. For example, they introduce MOS Process and briefly review the CMOS building blocks and the four available components. In the next section the authors describe Memory cell operations in- cluding Read and Erase operations, as well as coverage of software and program issues. Comprehensive sections on Design Building Blocks, Integrated circuits layout, and Matrix architecture are included. They explore in some depth Input buffers, Output Buffers Decoders and Program and Erase operations circuitry. They discuss the subjects of Timers and Read operation sensing techniques. Two sections deal with quality and dependability-related issues, and cover the subjects of Redundancy and Test Modes. Coverage is also provided on ESD & latch-up issues as well as Embedded Flash algorithms. A collection of photos is included to make the reader familiar with silicon as- pects. Throughout all parts of this book, the authors have taken a practical and applications-driven point of view, providing a comprehensive and easily understood approach to all the concepts discussed. I greatly appreciate the very kind invitation of the authors to submit these words of introduction for their exciting new book. I wish them continued success in their latest publishing enterprise, but more importantly I hope that all who are reading these words will derive knowledge and understanding from the sincere and dedicated efforts of the authors. Jim Calder Managing Editor PROCEEDINGS OF THE IEEE Acknowledgements Introducing this book, we want to acknowledge the contribution of all those people who greatly helped us in the preparation of the manuscript. Our colleague Roberto Ravasio, who took care of the sections related to the logic, the burst, the description of the algorithms executed by the Flash and related implementation, either using PLA methodology or the sequencer. Our colleagues Miriam Sangalli and Ilaria Motta for the section related to charge pumps and regulators, and again Ilaria Motta for the High Voltage Man- agement section. We also wish to thank Paolo Cappelletti, ST Non Volatile Memory Technology Development Director in Agrate, who wrote the foreword for this book. Paolo, who has always supported the various initiatives that we have undertaken in these years, has shown once again his availability and his passion for this kind of activities. We also want to thank Jim Calder, Managing Editor for the Proceedings of the IEEE: the publication of the Proceedings allowed us to contact the Editor for this book. Jim has written the preface to the text. We have to thank Dieter Merkle for giving us the possibility of publishing this work together with Gaby Maas who greatly helped us as editor. Special thanks to Adalberto Micheloni for drafts review. Last but not least, we wish to thank our colleagues Marcello Pesare and Stefano Commodaro, who have taken care of the translation of the text from Italian to English. Our thanks go to all these people and to many others who have indirectly con- tributed to this book with their job work and dedication. Gianni, Rino and Dave Contents Foreword: Non-Volatile Memory Technology Evolution ...............................................XVII Systems Needs for Non-Volatile Storage.................................................XVIII NOR Flash Memory................................................................................... XXI NAND Flash Memory..............................................................................XXIII New Memory Concepts.............................................................................XXV Conclusions...........................................................................................XXVIII 1 Non-Volatile Memory Design....................................................................... 1 1.1 Introduction ........................................................................................ 1 1.2 Main Features of Non-Volatile Memories.......................................... 2 1.3 Program .............................................................................................. 3 1.4 Erase ................................................................................................... 4 1.5 Distributions and Cycles..................................................................... 4 1.6 Read Mode Architecture..................................................................... 7 1.7 Write Mode Architecture.................................................................... 8 1.8 Erase Mode Architecture .................................................................... 9 1.9 Elements of Reliability ..................................................................... 10 1.10 Influence of Temperature and Supply Voltage................................. 10 1.11 Lab Activities ................................................................................... 11 1.12 Working Tools.................................................................................. 12 1.13 Shmoo Plots.....................................................................................

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