Silicon Technologies: Ion Implantation and Thermal Treatment

347 Pages·17.629 MB·English

Silicon Technologies
Silicon Technologies
Ion Implantation and Thermal Treatment

Edited by
Annie Baudrant
First published 2011 in Great Britain and the United States by ISTE Ltd and John Wiley & Sons, Inc.
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 John Wiley & Sons, Inc.
27-37 St George’s Road 111 River Street
London SW19 4EU Hoboken, NJ 07030
UK USA
www.iste.co.uk www.wiley.com
© ISTE Ltd 2011

The rights of Annie Baudrant to be identified as the author of this work have been asserted by her in
accordance with the Copyright, Designs and Patents Act 1988.
____________________________________________________________________________________
Library of Congress Cataloging-in-Publication Data

Silicon technologies : ion implantation and thermal treatment / edited by Annie Baudrant.
p. cm.
Includes bibliographical references and index.
ISBN 978-1-84821-231-2
1. Semiconductor doping. 2. Ion implantation. 3. Semiconductors--Heat treatment. I. Baudrant, Annie.
TK7871.85.S5485 2011
621.3815'2--dc22
2011008131

British Library Cataloguing-in-Publication Data
A CIP record for this book is available from the British Library
ISBN 978-1-84821-231-2

Printed and bound in Great Britain by CPI Antony Rowe, Chippenham and Eastbourne.
Table of Contents
Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi
Annie BAUDRANT
Chapter 1. Silicon and Silicon Carbide Oxidation . . . . . . . . . . . . . . . . 1
Jean-Jacques GANEM and Isabelle TRIMAILLE
1.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2. Overview of the various oxidation techniques . . . . . . . . . . . . . . . 3
1.2.1. General information . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2.2. Most frequently used methods in the semiconductor industry . . . . 4
1.2.3. Other methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
1.3. Some physical properties of silica . . . . . . . . . . . . . . . . . . . . . . 17
1.3.1. The silica structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
1.3.2. Three useful parameters of silica . . . . . . . . . . . . . . . . . . . . . 21
1.3.3. Transport properties in silica . . . . . . . . . . . . . . . . . . . . . . . 22
1.4. Equations of atomic transport during oxidation . . . . . . . . . . . . . . 28
1.4.1. Transport equations in the general case . . . . . . . . . . . . . . . . . 29
1.4.2. First approximation: C(x) varies slowly with the depth x . . . . . . 30
1.4.3. Second approximation: (x) varies slowly with the depth x . . . . 33
1.4.4. Applications of the transport equations to thermal and
anodic oxidation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
1.5. Is it possible to identify the transport mechanisms taking
place during oxidation? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
1.5.1. Identification using isotopic labeling techniques . . . . . . . . . . . 35
1.5.2. Important results for the thermal oxidation of silicon
under dry O . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
2
1.5.3. Important results for wet thermal oxidation . . . . . . . . . . . . . . 45
vi Silicon Technologies
1.5.4. Conclusions on the atomic transport mechanisms during
silicon thermal oxidation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
1.5.5. Experimental results and conclusions on the transport
mechanisms during the anodic oxidation of silicon . . . . . . . . . . . . . . 46
1.5.6. Important experimental results from dry SiC thermal
oxidation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
1.6. Transport equations in the case of thermal oxidation . . . . . . . . . . . 48
1.6.1. General information on flux and on growth kinetics . . . . . . . . . 48
1.6.2. Flux calculation for neutral mobile species . . . . . . . . . . . . . . . 49
1.6.3. Flux calculation for ion mobile species . . . . . . . . . . . . . . . . . 49
1.7. Deal and Grove theory of thermal oxidation . . . . . . . . . . . . . . . . 53
1.7.1. Flux calculation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
1.7.2. Growth kinetics equations . . . . . . . . . . . . . . . . . . . . . . . . . 57
1.7.3. Remarks on the fluctuations of the oxidation constants
k and k . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
P L
1.7.4. Determination of the oxidation parameters from
experimental results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
1.7.5. Confrontation of the Deal and Grove theory with
experimental results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
1.7.6. Conclusions on the Deal and Grove theory . . . . . . . . . . . . . . . 66
1.8. Theory of thermal oxidation under water vapor of silicon . . . . . . . . 67
1.8.1. Concentration profiles expected for H O . . . . . . . . . . . . . . . . 67
2
1.8.2. Concentration profiles expected for the OH groups . . . . . . . . . . 68
1.8.3. Concentration profiles expected for H . . . . . . . . . . . . . . . . . 68
2
1.8.4. Concentration profiles expected for H . . . . . . . . . . . . . . . . . . 69
1.8.5. Comparison of the expected and the experimental profiles . . . . . 71
1.8.6. Wolters theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
1.9. Kinetics of growth in O for oxide films < 30 nm . . . . . . . . . . . . . 72
2
1.9.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
1.9.2. Oxidation models of thin films . . . . . . . . . . . . . . . . . . . . . . 78
1.9.3. Case of ultra-thin films (< 5 nm) . . . . . . . . . . . . . . . . . . . . . 80
1.9.4. On line simulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
1.9.5. Kinetics and models of SiC oxidation . . . . . . . . . . . . . . . . . . 81
1.10. Fluctuations of the oxidation constants under experimental
conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
1.10.1. Role of the pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
1.10.2. Role of the temperature . . . . . . . . . . . . . . . . . . . . . . . . . 85
1.10.3. Role of the crystal direction . . . . . . . . . . . . . . . . . . . . . . . 88
1.10.4. Role of doping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
1.11. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
1.12. Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
Table of Contents vii
Chapter 2. Ion Implantation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
Jean-Jacques GROB
2.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
2.2. Ion implanters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
2.2.1. General description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
2.2.2. Ion sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
2.2.3. Mass analysis and beam optics . . . . . . . . . . . . . . . . . . . . . . 107
2.2.4. Current measurement. . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
2.2.5. Production throughput, temperature control and charge effects . . . 109
2.3. Ion range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
2.3.1. Binary collision and stopping power . . . . . . . . . . . . . . . . . . 111
2.3.2. Profile of the implanted ions . . . . . . . . . . . . . . . . . . . . . . . 115
2.3.3. Backscattering, surface sputter and channeling . . . . . . . . . . . . 119
2.3.4. Implantation through a mask . . . . . . . . . . . . . . . . . . . . . . . 122
2.4. Creation and healing of the defects . . . . . . . . . . . . . . . . . . . . . . 124
2.4.1. Primary collision and cascade . . . . . . . . . . . . . . . . . . . . . . 124
2.4.2. Point defects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
2.4.3. Accumulation of damages, amorphization . . . . . . . . . . . . . . . 128
2.4.4. Damage healing and dopant activation . . . . . . . . . . . . . . . . . 132
2.5. Applications in traditional technologies and new tendencies . . . . . . . 136
2.5.1. Common implantations . . . . . . . . . . . . . . . . . . . . . . . . . . 137
2.5.2. Other applications and new tendencies . . . . . . . . . . . . . . . . . 140
2.6. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
2.7. Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
Chapter 3. Dopant Diffusion: Modeling and Technological
Challenges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
Daniel MATHIOT
3.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
3.2. Diffusion in solids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157
3.2.1. General information . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157
3.2.2. Elementary mechanisms . . . . . . . . . . . . . . . . . . . . . . . . . . 163
3.2.3. Semiconductor specificities . . . . . . . . . . . . . . . . . . . . . . . . 172
3.3. Dopant diffusion in single-crystal silicon . . . . . . . . . . . . . . . . . . 176
3.3.1. Predeposition methods . . . . . . . . . . . . . . . . . . . . . . . . . . . 176
3.3.2. Main experimental observations . . . . . . . . . . . . . . . . . . . . . 178
3.3.3. Modeling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184
3.4. Examples of associated engineering problems . . . . . . . . . . . . . . . 191
3.4.1. Redistribution of the implanted dopants: transient enhanced
diffusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191
3.4.2. Engineering of ultra-thin junctions . . . . . . . . . . . . . . . . . . . . 193
3.4.3. Reverse short channel effect . . . . . . . . . . . . . . . . . . . . . . . 195
viii Silicon Technologies
3.5. Dopant diffusion in germanium . . . . . . . . . . . . . . . . . . . . . . . . 196
3.5.1. Thermal diffusion process . . . . . . . . . . . . . . . . . . . . . . . . . 197
3.5.2. Implanted dopants and junctions engineering . . . . . . . . . . . . . 199
3.6. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201
3.7. Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201
Chapter 4. Epitaxy of Strained Si/Si1-x Gex Heterostructures . . . . . . . . 209
Jean-Michel HARTMANN
4.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209
4.1.1. General introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209
4.1.2. Chemical vapor deposition from the beginning . . . . . . . . . . . . 210
4.1.3. The Epi Centura epitaxy tool . . . . . . . . . . . . . . . . . . . . . . . 216
4.1.4. Some general concepts of epitaxy . . . . . . . . . . . . . . . . . . . . 219
4.2. Engineering of the pMOSFET transistor channel using
pseudomorphic SiGe layers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222
4.2.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222
4.2.2. Growth kinetics of Si and SiGe in chlorinated chemistry . . . . . . 224
4.2.3. Transposition on patterned substrates . . . . . . . . . . . . . . . . . . 229
4.2.4. pMOS transistors incorporating SiGe layers . . . . . . . . . . . . . . 231
4.3. Engineering of the nMOSFET transistor channel using
pseudomorphic Si C layers; SiGeC diffusion barriers . . . . . . . . . . . . 233
1-y y
4.3.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233
4.3.2. Incorporation of C in Si and SiGe . . . . . . . . . . . . . . . . . . . . 235
4.3.3. Si/Si C /Si stacks for nMOS transistors . . . . . . . . . . . . . . . . 238
1-y y
4.3.4. nMOS transistors incorporating Si C layers or SiGeC
1-y y
diffusion barriers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241
4.4. Epitaxy of Si raised sources and drains on ultra-thin SOI
substrates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243
4.4.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243
4.4.2. Problems encountered on ultra-thin SOI substrates . . . . . . . . . . 245
4.4.3. Method developed in response . . . . . . . . . . . . . . . . . . . . . . 246
4.5. Epitaxy of recessed and raised SiGe:B sources and drains on
ultra-thin SOI and SON substrates . . . . . . . . . . . . . . . . . . . . . . . . . 248
4.5.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 248
4.5.2. Growth kinetics and boron doping of SiGe in chlorinated
chemistry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 249
4.5.3. Recessed and raised SiGe:B sources and drains on FD-SOI
and SON substrates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251
4.6. Virtual SiGe substrates: fabrication of sSOI substrates and
of dual c-Ge / t-Si channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253
4.6.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253
4.6.2. Growth and structural properties of virtual SiGe substrates . . . . . 255
Table of Contents ix
4.6.3. Growth and structural properties of tensily-strained Si layers
on SiGe virtual substrates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262
4.6.4. Fabrication of sSOI and XsSOI substrates & transport
properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 267
4.6.5. c-Ge/t-Si dual channels on Si Ge virtual substrates . . . . . . . . 271
0.5 0.5
4.7. Thin or thick layers of pure Ge on Si for nano and
opto-electronics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 275
4.7.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 275
4.7.2. Structural properties of thick layers of Ge on Si (001)
and of GeOI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 276
4.7.3. Optical and transport properties of thick Ge layers on
Si (001) and of GeOI substrates . . . . . . . . . . . . . . . . . . . . . . . . . 283
4.7.4. Structural and optical properties of Ge islands on Si (001) . . . . . 288
4.8. Devices based on sacrificial layers of SiGe . . . . . . . . . . . . . . . . . 292
4.8.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 292
4.8.2. Selective HCl etching of SiGe selectively compared to Si . . . . . . 293
4.8.3. Localized SOI devices and SON . . . . . . . . . . . . . . . . . . . . . 297
4.8.4. Devices based on multi-wires and on multi-channels . . . . . . . . . 301
4.9. Conclusions and prospects . . . . . . . . . . . . . . . . . . . . . . . . . . . 311
4.9.1. General conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 311
4.9.2. Prospects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 313
4.10. Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 317
List of Authors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 333
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 335
Preface
Electronic components based on semiconductors are at the core of all electrical
and electronic equipment. They are stakeholders of an increasing share of the objects
surrounding and accompanying us. They give to these objects various functions:
capture, storage, transmission or information restoration (cameras, phones, TV, etc.),
control-command, aid to decision-making, safety, etc.
Nowadays, the components aggregate more than 20% of the value of electrical or
electronic equipment, against 7% in 1985. Therefore, there is a global market of the
“semiconductor” sector of 270 billion dollars.
These components are indeed at the heart of all applications, for the “digital
society”, of which they ensure both the engine and the memory, or for the
improvements expected in the fields of transport, aeronautics, health, safety, and
electrical energy management close to the user or within distribution systems.
Broadband available to all, the intelligent and efficient management of energy in
buildings, telehealth, the intelligent road and zero emission cars or even the
replacement of the electrical infrastructure, go inevitably through an increasing use
of electronic components with more complex and powerful semiconductors.
The number of delivered components amounts to billions of parts per week
(3.25 billion of units/week, at the end of December 2009).
This increasing and continuous penetration of electronic components in
equipment was made possible by two other key features of the sector, which have
been permanent over the last four decades:
– the monolithic and collective fulfillment or the increasing integration, of
complex electronic functions (combination of elementary components) on hardware
xii Silicon Technologies
support, which constitutes an integrated silicon circuit, with a fast renewal of
products and technologies;
– the continuous reduction of manufacturing costs and unit prices.
For the driving markets of the memories, of the specific processors and digital
circuits, the production is primarily based on CMOS technologies. They are
characterized by the most critical dimension of the transistors constituting them.
Thus, the “40 nm node” corresponds to the technology, where this lower limit
measures 40 nm.
Nowadays, the most aggressive generation of production is the 40 nm node, but
the 28 nm node will be proposed in production from the next half-year.
The dimensions’ reduction, for which the transistors (elementary components of
the integrated circuits) are produced, is at the heart of two important product
evolutions:
– the rise in performance (transistor speed, related to the minimal size of these
elementary components);
– the integration of a growing number of transistors, today exceeding a billion
per circuit.
The evolution of technologies leading to this increasing integration is fast. It
follows an empirical prediction made by Gordon Moore (cofounder of Intel), of an
integration doubled every 18 months. Unequalled fact in any industrial sector, this
technical evolution of the products has lasted for four decades (see Figure 1).
The manufacturing technologies of electronic components have evolved a lot
since the invention of the first transistor: we went from an element the size of a 1€
coin to submicron dimensions (45 nm previewed at IBM in spring 2006, while in
December 2007, the TSMC group sampled SRAMs in 32 nm technology.
Nowadays, we are heading for 22 nm and below).
Nevertheless, some principles have been preserved, and of course the technology
is subjected to constraints, resulting from the fundamental properties of the
semiconductors, such as they appear in the chapters on the components’ physics. Let
us note however that 32 nm noticeably represents the thickness of a hundred atomic
lines, and that we imperceptibly come near a limit below which we will no longer be
able to go, except by completely changing the principles.