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CMOS ACTIVE PIXEL SENSOR DESIGNS FOR FAULT TOLERANCE AND BACKGROUND ILLUMINATION SUBTRACTION Desmond Yu Hin Cheung B.A.Sc. Simon Fraser University 2002 THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF APPLIED SCIENCE in the School of Engineering Science O Desmond Yu Hin Cheung 2005 SIMON FRASER UNIVERSITY Summer 2005 All rights reserved. This work may not be reproduced in whole or in part, by photocopy or other means, without permission of the author. APPROVAL Name: Desmond Yu Hin Cheung Degree: Master of Applied Science Title of Thesis: CMOS Active Pixel Sensor for Fault Tolerance and Background Illumination Subtraction Examining Committee: Chair: Dr. Faisal Beg Assistant Professor Dr. Glenn Chapman Senior Supervisor Professor Dr. Ash Parameswaran Supervisor Professor Dr. Karim Karim Examiner Assistant Professor Date Approved: J,,,,p 13 zoos SIMON FRASER UNIVERSITY PARTIAL COPYRIGHT LICENCE The author, whose copyright is declared on the title page of this work, has granted to Simon Fraser University the right to lend this thesis, project or extended essay to users of the Simon Fraser University L~brary, and to make partial or single copies only for such users or in response to a request from the library of any other university, or other educational institution, on its OWTI behalf or for one of its users. The author has hrther granted permission to Simon Fraser University to keep or make a digital copy for use in its circulating collection. The author has further agreed that permission for multiple copying of this work for scholarly purposes may be granted by either the author or the Dean of Graduate Studies. It is understood that copying or publication of this work for financial gain shali not be aliowed without the author's written permission. Permission for public performance, or lirn~tedpermission for private scholarly use, of any multimedia materials forming part of this work, may have been granted by the author. This information may be found on the separately catalogued multimedia material and m the s~gnedPartial Copyright Licence. The original Partial Copyright Licence attesting to these terms, and signed by this author, may be found in the original bound copy of this work, retained in the Simon Fraser University Archive. W. A. C. Bennett Library Simon Fraser University Burnaby, BC, Canada ABSTRACT As the CMOS active pixel sensor evolves, its weaknesses are being overcome and its strengths start to surpass that of the charge-coupled device. This thesis discusses two novel APS designs. The first novel APS design was a Fault Tolerance Active Pixel Sensor (FTAPS) to increase a pixel's tolerance to defects. By dividing a regular APS pixel into two halves, the reliability of the pixel is increased, resulting in higher fabrication yield, longer pixel life time, and reduction in cost. Photodiode-based FTAPS pixels were designed, fabricated in CMOS 0.18 micron technology, and tested. Experimental results demonstrated that the reliability of the pixel is increased and information that would have been lost without fault tolerance is recovered. The second novel APS pixel was designed to eliminate background illumination when a detector attempts to locate a desired laser signal. This pixel design, namely the Duo-output APS (DAPS), consists of an extra output path, such that a signal can be selectively readout to one of the two paths at different time of a cycle. During one half of a given cycle while the foreground signal is turned on, the sensor detects both the background and foreground levels. During the other half of the cycle, the foreground is off, thus only the background level is detected. The difference of the two outputs is the desired foreground signal without the background noise. DAPS pixels were designed, fabricated in CMOS 0.18 micron technology, and tested. Testing results identified design changes that will improve the background subtraction. ACKNOWLEDGEMENTS First of all, I would like to thank my supervisor Prof. Glenn Chapman for his unlimited support and guidance throughout my graduate study at SFU, enabling the completion of this thesis. He has given me the opportunity to develop skills in various areas, including but not limited to chip design, testing, and conference presentation. I would also like to thank Dr. Ash Parameswaren and Dr. Karim Karim for their technical advice and for their work as my committee members. I would also like to thank Dr. Faisal Beg for his advice and expertise as the thesis defence chair. I would also like to thank Mr. Bill Woods and Dr. Richard Yuqiang Tu for their support with cleanroom and laser room equipment. Both of them have assisted me in preparation, setup, and testing of the image sensors. I would also like to thank Dr. Chinheng Choo for his tremendous support in the development of the LabVlEW software for the APS experiments. Without his help, it would have been a much difficult time to setup the control signals for the APS chips. I would like to thank my colleague Mr. Sunjaya Djaja, whom I have worked closely with, for his inputs and encouragements throughout the entire period of this degree. I would like to thank Hermary Opto Electronics for their supports and encouragements for this project. I thank them for their patience as they waited a long time for the design, fabrication, testing of the chips. I would like to thank Ms. Michelle La Haye and Mr. Cory Jung for proofreading this thesis document. I would like to thank Benjamin Wang and Gary Liaw for their help in setting up the testing equipment. I would also like to thank everyone in the "glenn-sardine" research area for all the fun that we had and their understanding and generosity in sharing the lab and laser equipment. Finally but not least, I would like to thank my parents and my wife for their tremendous support, understanding, and patience during all these years. Most importantly, I would like to thank The Almighty God for His grace and that He has given me the courage, wisdom, and guidance along the way during my time in Simon Fraser University. TABLE OF CONTENTS .. Approval ............................................................................................................................11 ... Abstract .............................................................................................................................111 Acknowledgements ..........................................................................................................iv Table of Contents ............................................................................................................. vi List of Figures ................................................................................................................... ix List of Tables .................................................................................................................. xm... Glossary or List of Abbreviations and Acronyms ...................................................... xiv Chapter One .Introduction .........................................................................1 Active Pixel Sensor ......................................................................................... 1 Digital Camera ................................................................................................. 2 Objectives ....................................................................................................... .5 Sensors and Yield ........................................................................................ 5 Fault Tolerant Active Pixel Sensor .............................................................. 6 Optical Scanning Detector with Background Light Elimination ................. 6 Duo-Output Active Pixel Sensor ................................................................. 7 Overview ........................................................................................................ -8 Chapter Two .Review of Photo-Detectors and Image Sensors ................9 Silicon Photo-Detector for Visible Light ........................................................ 9 Absorption of Optical Signal by Silicon .................................................... 10 Electron-Hole Pair Generation .................................................................. 11 Measurement of Photo-Generated Charges ............................................... 13 Charge-Coupled Device ................................................................................ 14 Operation of CCD ...................................................................................... 16 Figures of Merit for CCD .......................................................................... 18 Future of CCD ........................................................................................... 21 Photodiode ..................................................................................................... 21 Operation of Photodiode ............................................................................23 Photodiode Model ......................................................................................25 Figures of Merit for Photodiode ................................................................26 Active Pixel Sensor .......................................................................................27 Photodiode-Based APS ..............................................................................28 Photogate-Based APS ................................................................................32

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