Mercury Cadmium Telluride Imagers A Patent-oriented Survey HANDBOOK OF SENSORS AND ACTUATORS Series Editor: S. Middelhoek, Delft University of Technology, The Netherlands Volume 1 Thick Film Sensors (edited by M. Prudenziati) Volume 2 Solid State Magnetic Sensors (by C.S. Roumenin) Volume 3 Intelligent Sensors (edited by H. Yamasaki) Volume 4 Semiconductor Sensors in Physico-Chemical Studies (edited by L. Yu. Kupriyanov) Volume 5 Mercury Cadmium Telluricle Imagers (A. Onshage) HANDBOOK OF SENSORS AND ACTUATORS 5 Mercury Cadmium Tel luride I magers A Patent-oriented Survey Anders C. Onshage European Patent Office The Hague, The Netherlands 1997 ELSEVIER Amsterdam - Lausanne - New York - Oxford - Shannon - Tokyo ELSEVIER SCIENCE B.V. Sara Burgerhartstraat 25 P.O. Box 211, 1000 AE Amsterdam, The Netherlands ISBN: 0 444 82790 0 (cid:14)91 997 Elsevier Science B.V. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior written permission of the publisher, Elsevier Science B.V., Copyright & Permissions Department, P.O. Box 521, 1000 AM Amsterdam, The Netherlands. Special regulations for readers in the U.S.A. - This publication has been registered with the Copyright Clearance Center Inc. (CCC), 222 Rosewood Drive, Danvers, MA 01923. Information can be obtained from the CCC about conditions under which photocopies of parts of this publication may be made in the U.S.A. All other copyright questions, including photocopying outside of the U.S.A., should be referred to the publisher, Elsevier Science B.V. No responsibility is assumed by the publisher for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions or ideas contained in the material herein. This book is printed on acid-free paper. Printed in The Netherlands Introduction to .the Series The arrival of integrated circuits with very good performance/price ratios and relatively low- cost microprocessors and memories has had a profound influence on many areas of technical endeavour. Also in the measurement and control field, modern electronic circuits were introduced on a large scale leading to very sophisticated systems and novel solutions. However, in these measurement and control systems, quite often sensors and actuators were applied that were conceived many decades ago. Consequently, it became necessary to improve these devices in such a way that their performancedpdce ratios would approach that of modem electronic circuits. This demand for new devices initiated worldwide research and development programs in the field of "sensors and actuators'. Many generic sensor technologies were examined, from which the thin- and thick-film, glass fiber, metal oxides, polymers, quartz and silicon technologies are the most prominent. A growing number of publications on this topic started to appear in a wide variety of scientific journals until, in 1981, the scientific journal Sensors and Actuators was initiated. Since then, it has become the main journal in this field. When the development of a scientific field expands, the need for handbooks arises, wherein the information that appeared earlier in journals and conference proee~ings is systematically and selectively presented. The sensor and actuator field is now in this position. For this reason, Elsevier Science took the initiative to develop a series of handbooks with the name "Handbook of Sensors and Actuators" which will contain the most meaningful background material that is important for the sensor and actuator field. Titles like Fundamentals of Transducers, Thick Film Sensors, Magnetic Sensors, Micromachining, Piezoelectric Crystal Sensors, Robot Sensors and Intelligent Sensors will be part of this series. The series will contain handbooks compiled by only one author, and handbooks written by many authors, where one or more editors bear the responsibility for bringing together topics and authors. Great care was given to the selection of these authors and editors. They are all well known scientists in the field of sensors and actuators and all have impressive international reputations. Elsevier Science and I, as Editor of the series, hope that these handbooks will receive a positive response from the sensor and actuator community and we expect that the series will be of great use to the many scientists and engineers working in this exciting field. Simon Middelhoek Mercury. Cadmium Teiluride Imagers Summary The evolution of imager structures using Mercury Cadmium Telluride (HgCdTe) is described based on published patents and patent applications. The book is divided into two parts. The first describes monolithic arrays, with the detector elements and read-out means integrated in the same semiconductor body. The second part describes hybrid arrays, with the detector elements and the read-out means formed in separate semiconductor bodies. The types of monolithic arrays discussed are charge coupled device imagers, ambipolar driR field imagers, static induction transistor imagers, charge injection device imagers and charge imaging matrices. The part on hybrid arrays has specific chapters on flip-chip arrangements, Z- technology arrangements, and arrays with the detector array directly contacting the read-out chip. The remaining hybrid arrays are separated according to whether the detector elements are provided with individual read-out leads or not. The cited documents are presented with an introductory part followed by a descriptive part which in most cases includes one or more figures. An overview of the subject of this book may be aquired by reading only the introductory parts in combination with the figures. A patent number index with information about the patent applicants, inventors, priorities and patent-families, an inventor index, a company index, and a subject index can be found at the end of the book. VI.oI Preface This book is an attempt to describe the evolution of mercury cadmium telluride (HgCdTe) imager structures based on published patents and patent applications. Most of the patent documents cited in this book originate from the part of the systematic documentation at the European Patent Office (EPO) which corresponds to the International Patent Classification (IPC) H01L27/14 Focus has been directed to the structures of the imagers. The steps of manufacturing of the structures have been included when steps of specific interest have been disclosed. It has been necessary to exclude documents not explicitly mentioning mercury cadmium telluride to reduce the material to a manageable size. It should be noted that no verification of the feasibility of a device or its operation is needed to render it patentable. The analysis of certain Japanese patent applications have been limited to the published Patent Abstract of Japan. The patent number, the name of the applicant and the date of publication are indicated for each document cited in the book. A patent number index, an inventors index, a company index and a subject index is found at the end of the book. It is not unusual that a patent application has been filed in several countries referring to a common first filing i.e. priority. These applications are said to belong to the same patent- family. In this book English-speaking documents of the patent-families have been selected provided it has been possible. The patent numbers or patent application numbers of other documents belonging to the same patent-family as a cited document may be found in the patent number index at the end of the book. I HO1L27/14: Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate, including semiconductor components sensitive to infra-red radiation, light, electromagnetic radiation of a shorter wavelength, or corpuscular radiation of a shorter wavelength, or corpuscular radiation and adapted for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation. viii Mercury Cadmium Telluride Imagers The book is separated into a first part with monolithic arrays and a second part with hybrid arrays. Each part comprises five chapters. The documents of each chapter are placed in a chronological order with the documents with earliest priority placed first. The documents are separated by a star '*' Sometimes a document has been placed at a position which is earlier than that which corresponds to its priority date. This has been done when the document shares basic features with a document already presented in the chapter. The document then follows directly after the earlier document and the documents are separated by two stars'* *' I would like to express my appreciation to all the people who have assisted me in this work and especially to S. Behmo and A. Cardon, Directors at the EPO, L.J.L. Fransen, S. Greene, P. Gori and A. Visentin, Examiners at the EPO. It is my hope that this monography will serve as a useful summary of the patents and patent applications in the field of mercury cadmium telluride imagers. Rij swijk, 1995 A. C. Onshage Contents Introduction xi Part One: Monolithic Arrays Detector elements and read-out means are provided in the samq semiconductor body. 1.1 ChargeC oupled Device Imagers 1.2 AmbipolarD rift Field Imagers 21 1.3 StaticI nduction Transistor Imagers 39 1.4 ChargeI njection Device Imagers 49 1.5 ChargeI maging Matrices 71 Part Two: Hybrid Arrays 83 Detector elements and read-out means are provided in separate semiconductor bodies. 2.1 Detector Arrays with Individual Detector Element Read-Out Leads 85 Detector elements are provided with individual read-out leads formed in or on a non-active supporting substrate. 2.2 Detector Arrays without Individual Detector Element Read-Out Leads 123 Individual detector elements are provided with bump connectors or with no connectors at all. - Cross-TalkP reventing Measures 202 - Passivationa nd Leakage Current Preventing Measures 253 2.3 Flip-ChipA rrangements 269 - ThermalS tress Preventing Measures 289 2.4 Z-TechnologyA rrangements 309 2.5 Detector Arrays Directly Contacting the Read-Out Chip 329 - Connectionsm ade by Through Hole Technologies 374 Patent Number Index 401 Inventor Index 421 Company Index 433 Subject Index 437