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Frank Hartmann

Evolution of SiliconSensor Technologyin Particle Physics

123

Frank HartmannInstitut fur Experimentelle KernphysikUniversitat KarlsruheForschungszentrum KarlsruheHermann-v.-Helmholtz-Platz 176344 Eggenstein-LeopoldshafenGermanyFrank.Hartmann@CERN.CH

F. Hartmann, Evolution of Silicon Sensor Technology in Particle Physics, STMP 231(Springer, Berlin Heidelberg 2009), DOI 10.1007/ 978-3-540-44774-0

ISBN 978-3-540-25094-4 e-ISBN 978-3-540-44774-0

DOI 10.1007/978-3-540-44774-0

ISSN 0081-3869 e-ISSN 1615-0430

Physics and Astronomy Classification Scheme (PACS):SEMICONDUCTOR DETECTORS FOR NUCLEAR PHYSICS, 29.40.WK

Library of Congress Control Number: 2008936955

c© Springer-Verlag Berlin Heidelberg 2009

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Preface

In the post era of the Z and W discovery, after the observation of Jets at UA1 andUA2 at CERN, John Ellis visioned at a HEP conference at Lake Tahoe, Californiain 1983 “To proceed with high energy particle physics, one has to tag the flavour ofthe quarks!”

This statement reflects the need for a highly precise tracking device, being able toresolve secondary and tertiary vertices within high-particle densities. Since the dis-tance between the primary interaction point and the secondary vertex is proportionalto the lifetime of the participating particle, it is an excellent quantity to identify parti-cle flavour in a very fast and precise way. In colliding beam experiments this methodwas applied especially to tag the presence of b quarks within particle jets. It was firstintroduced in the DELPHI experiment at LEP but soon followed by all collider ex-periments to date. The long expected t quark discovery was possible mainly withthe help of the CDF silicon vertex tracker, providing the b quark information. Inthe beginning of the 21st century the new LHC experiments are beginning to takeshape. CMS with its 206 m2 of silicon area is perfectly suited to cope with the highluminosity environment. Even larger detectors are envisioned for the far future, likethe SiLC project for the International Linear Collider. Silicon sensors matured fromsmall 1 in. single-sided devices to large 6 in. double-sided, double metal detectorsand to 6 in. single-sided radiation hard sensors. A large group of researchers insidethe high energy physics community is steadily developing and investigating newdevices and is pushing the technology to new limits. These larger and larger devicesare the driving force to improve industrial processing and quality control. Also thereadout electronics evolved from microsecond to nanosecond integration times andto radiation-tolerant sub-micron technology devices.

This review describes the successes in high energy physics as well as the devel-opments in technology from the early days of NA11 to the current detector CMS atthe LHC, ending with an outlook for detectors in a very early design phase for thefuture linear collider and the super-LHC. Also the day-to-day life in a silicon labora-tory and the practical handling and testing strategies are described. Particle Physicsexamples will be given to underline the importance of silicon tracking devices forhigh energy physics.

Karlsruhe,August 2008 Frank Hartmann

v

Acknowledgments

I truly thank all my colleagues from DELPHI, CDF, CMS of the last decade andmore for either supporting me or making my life interesting! I am well aware thatunfortunately I am not able to credit every person individually for all their invaluableimpact on all the projects. The author lists of DELPHI, CDF and CMS are simplytoo long. I apologize if your name does not explicitly appear where it should.

I am especially grateful to Wim de Boer and Thomas Muller, Joe Incandela andLuigi Rolandi who supported me so much and who always had such confidencein me.

With great pleasure I also acknowledgeHans Dijkstra, Paul Collins and Gunnar Maehlum for insights during my under-

graduate thesis and for the Delphi structures which I was able to borrow – the sourceof many photos here;

Pia Steck and Tobias Barvich from Karlsruhe who relentlessly made many photosand drawings, now published here;

Duccio Abbaneo, Thomas Bergauer, Gino Bolla, Peter Blum, Alexander Dier-lamm, Guido Dirkes, Diana Fellner, Jean-Charles Fontaine, Karl Gill, Oliver Holme,Joe Incandela, Manfred Krammer, Jacek Marczewski, Michael Moll, Thomas Muller,Steve Nahn and Robert Stringer; without their meticulous proof reading and invalu-able comments, publishing this monography would have been impossible;

The German Bundesministerium fur Bildung und Forschung BMBF, the DeutscheForschungsgemeinschaft and the Land of Baden-Wurttemberg making the describedresearch possible by financially supporting it;

The people dearest to me: Dana and Gwen, my daughter Sara and my motherMarianne who endured many hours of absence either due to my “detector obliga-tions” or writing this monography.

Several schematics are inspired by Bergmann and Schafer, Sze, from Hyper-script of H. Foll and lectures of Carl Haber, Alan Honma, Paula Collins, ManfredKrammer, Michael Moll and Lucia Silvestris.

Missing even a single one of the dear people mentioned above, I never wouldhave been able to finish this monography.

Frank Hartmann

vii

Contents

1 Basic Principles of a Silicon Detector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.1 Fundamental Silicon Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.1.1 Just Silicon and Some Impurities . . . . . . . . . . . . . . . . . . . . . . . 21.1.2 The pn-Junction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71.1.3 SiO2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151.1.4 Summary of Silicon Properties . . . . . . . . . . . . . . . . . . . . . . . . . 18

1.2 Ingredients to Use Silicon as Detector Basis . . . . . . . . . . . . . . . . . . . . 191.3 Working Principle of a Silicon Tracking Device . . . . . . . . . . . . . . . . . 211.4 Single Sided–Double Sided, Double Metal . . . . . . . . . . . . . . . . . . . . . 261.5 Noise Contributions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261.6 Sensor Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

1.6.1 Global Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301.6.2 Bias-, Guard- and Outside Protection Rings . . . . . . . . . . . . . . 321.6.3 Design of Strip Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

1.7 Practical Aspects of Handling and Testing Silicon Strip Devices . . . 441.7.1 Standard/Exhaustive Set of Quality Assurance Tests . . . . . . . 45

1.8 Production of Silicon Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 471.8.1 From Pure Sand to Detector Grade Silicon . . . . . . . . . . . . . . . 481.8.2 Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

1.9 Readout Electronics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 581.10 Radiation Damage in Silicon Detector Devices . . . . . . . . . . . . . . . . . . 64

1.10.1 Bulk Damage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 641.10.2 Surface Damage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

1.11 Other Silicon Detector Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 801.11.1 Hybrid Pixels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 801.11.2 CMOS Detectors – Monolithic Active Pixels (MAPS) . . . . . 821.11.3 Silicon on Insulator Detector SOI . . . . . . . . . . . . . . . . . . . . . . . 831.11.4 Silicon Drift Detector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 841.11.5 Depleted Field Effect Transistors (DEPFET) Detectors . . . . 851.11.6 3D Silicon Detectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 861.11.7 Technology Advantage–Disadvantage – Usage . . . . . . . . . . . 88

1.12 Some Last Words About the Design of Detectors for High EnergyPhysics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

1.13 Some Always Unexpected Problems Along the Way . . . . . . . . . . . . . 90

ix

x Contents

2 First Steps with Silicon Sensors: NA11 (Proof of Principle) . . . . . . . . . . 972.1 From Semiconductor Detectors in the 1950s as Spectroscopes to

First Tracking Devices in the 1980s . . . . . . . . . . . . . . . . . . . . . . . . . . . 972.2 Development of the First Silicon Strip Detector for High Energy

Physics NA11 and NA32 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 982.3 Distinguish c Quarks from Others . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100

3 The DELPHI Microvertex Detector at LEP . . . . . . . . . . . . . . . . . . . . . . . 1033.1 Design and Strategies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1033.2 The DELPHI Microvertex Detector 1996/1997 . . . . . . . . . . . . . . . . . . 1073.3 The Silicon Sensors of the DELPHI Microvertex Detector (MVD) . 1123.4 Silicon Labs in Universities to Build a Large Device . . . . . . . . . . . . . 1173.5 Physics with the DELPHI Microvertex Detector . . . . . . . . . . . . . . . . . 118

4 CDF: The World’s Largest Silicon Detector in the 20th Century;the First Silicon Detector at a Hadron Collider . . . . . . . . . . . . . . . . . . . . 1234.1 Historical Evolution of the CDF Vertex Detector . . . . . . . . . . . . . . . . 1234.2 Design, How to Cover |η ≤ 2| Without Endcap . . . . . . . . . . . . . . . . . 128

4.2.1 Tracking System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1284.3 Six Inch, a New Technology Step for Large Silicon Applications . . . 1374.4 Lessons Learned from Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1424.5 The t Discovery, CP Violation in the b Quark Sector . . . . . . . . . . . . . 144

5 CMS: Increasing Size by 2 Orders of Magnitude . . . . . . . . . . . . . . . . . . . 1475.1 Design, How to Survive 10 Years in the Radiation Environment

of LHC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1575.1.1 Electronics – Quarter Micron Technology . . . . . . . . . . . . . . . . 1585.1.2 Silicon Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159

5.2 Construction Issues for Large Detector Systems with IndustryInvolvement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1665.2.1 Quality Assurance and Problems During the Process . . . . . . . 1675.2.2 Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169

5.3 Physics with the CMS Tracker and High-Level Trigger . . . . . . . . . . . 172

6 Continuing the Story: Detectors for the SLHC and the ILC . . . . . . . . . 1796.1 A Silicon Tracker for the Super Large Hadron Collider (SLHC) . . . . 1806.2 A Silicon Tracker for the International Linear Collider (ILC) . . . . . . 183

7 Conclusion and Outlook . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197

Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203