ISBN: 3540661999
TITLE: Technology of Integrated Circuits
AUTHOR: D. Widmann, H. Mader, H. Friedrich
TOC:

List of Symbols XIII
Key to the different layers in integrated circuits XVIII
1 Introduction 1
2 Basic principles of integrated circuits technology 3
3 Film technology 13
3.1 Film production processes 13
3.1.1 The CVD process 13
3.1.2 Thermal oxidation 20
3.1.3 Vapour phase deposition 27
3.1.4 Sputtering 29
3.1.5 Spin coating 33
3.1.6 Film production by ion implantation 34
3.1.7 Film production using wafer-bonding and back-etching 34
3.1.8 Annealing techniques 35
3.2 The monocrystalline silicon wafer 38
3.2.1 Geometry and crystallography of silicon wafers 38
3.2.2 Doping of silicon wafers 39
3.2.3 Monocrystalline silicon growing techniques 39
3.3 Epitaxial layers 41
3.3.1 Uses for epitaxial layers 41
3.3.2 Diffusion of doping atoms from the substrate into the epitaxial layer 43
3.4 Thermal SiO_2 layers 46
3.4.1 Uses of thermal SiO_2 layers 46
3.4.2 The LOCOS technique 47
3.4.3 Properties of thin thermal SiO_2 films 53
3.5 Deposited SiO_2 films 59
3.5.1 Creating deposited SiO_2 films 59
3.5.2 Applications of deposited SiO_2 films 60
3.5.3 Spacer technology 60
3.5.4 Trench isolation 62
3.5.5 SiO_2 isolation films for multi-level metallization 62
3.6 Phosphorus glass films 63
3.6.1 Producing phosphorus glass films 64
3.6.2 Flow-glass 66
3.6.3 Thermal phosphorus glass 67
3.7 Silicon nitride films 67
3.7.1 Producing silicon nitride films 68
3.7.2 Nitride films as an Oxidation barrier 68
3.7.3 Nitride films as a capacitor dielectric 69
3.7.4 Using nitride films for passivation 70
3.8 Polysilicon films 70
3.8.1 Producing polysilicon films 70
3.8.2 Grain structure of polysilicon films 71
3.8.3 Conductivity of polysilicon films 72
3.8.4 Uses of polysilicon films 74
3.9 Silicide films 78
3.9.1 Producing silicide Films 79
3.9.2 Polycide films 81
3.9.3 Silication of source/drain regions 83
3.10 Refractory metal films 83
3.11 Aluminium films 85
3.11.1 Producing aluminium films 85
3.11.2 Crystal structure of aluminium films 86
3.11.3 Electromigration in aluminium interconnections 87
3.11.4 Aluminium-silicon contacts 88
3.11.5 Aluminium-aluminium contacts 90
3.12 Organic films 91
3.12.1 Spin-On glass films 91
3.12.2 Polyimide films 92
4 Lithography 95
4.1 Linewidth dimension, placement errors and defects 96
4.2 Photolithography 98
4.2.1 Photoresist films 98
4.2.2 Formation of photoresist patterns 102
4.2.3 Light intensity variation in the photoresist 105
4.2.4 Special photoresist techniques 110
4.2.5 Optical exposure techniques 116
4.2.6 Resolution capability of optical exposure techniques 119
4.2.7 Alignment accuracy of optical exposure equipment 130
4.2.8 Defects occurring in optical lithography 133
4.3 X-raylithography 134
4.3.1 Wavelength region for X-ray lithography 135
4.3.2 X-ray resists 136
4.3.3 X-ray sources 137
4.3.4 X-raymasks 142
4.3.5 Alignment procedure for X-ray lithographv 144
4.3.6 Radiation damage in X-ray lithography 144
4.3.7 Opportunities for Y-ray lithography 144
4.4 Electron lithography 145
4.4.1 Electron resists 145
4.4.2 Resolution capability of electron lithography 146
4.4.3 Electron beam pattern generators 148
4.4.4 Electron projection equipment 153
4.4.5 Alignment techniques in electron lithography 154
4.4.6 Radiation damage in electron lithography 154
4.5 Ion lithography 156
4.5.1 Ion resists 156
4.5.2 Ion beam writing 158
4.5.3 Ion beam projection 160
4.5.4 Resolution capability of ion lithography 162
4.6 Pattern generation without using lithography 166
5 Etching technology 169
5.1 Wet etching 170
5.1.1 Wet Chemical etching 170
5.1.2 Chemical-mechanical polishing 171
5.2 Dry etching 174
5.2.1 Physical dry etching 174
5.2.2 Chemical dry etching 176
5.2.3 Physical-chemical dry etching 178
5.2.4 Chemical etching reactions 186
5.2.5 Etching gases 188
5.2.6 Process optimization 188
5.2.7 Endpoint detection 193
5.3 Dry etch processes 196
5.3.1 Dry etching of silicon nitride 197
5.3.2 Dry etching of polysilicon 197
5.3.3 Dry etching of monocrystalline silicon 199
5.3.4 Dry etching of metal silicides and refractory metals 200
5.3.5 Dry etching of silicon dioxide 201
5.3.6 Dry etching of aluminium 203
5.3.7 Dry etching of polymers 205
6 Doping technology 207
6.1 Thermal doping 208
6.2 Doping by ion implantation 209
6.2.1 Ion implantation machines 209
6.2.2 Implanted doping profiles 211
6.3 Activation and diffusion of dopant atoms 219
6.3.1 Activating implanted dopant atoms 219
6.3.2 Intrinsic diffusion of dopant atoms 220
6.3.3 Diffusion for high concentrations of dopant atoms 223
6.3.4 Oxidation enhanced diffusion 224
6.3.5 Diffusion of dopant atoms at interfaces 225
6.3.6 Diffusion of dopant atoms in films 227
6.3.7 Sheet resistance of doped layers 229
6.3.8 Diffusion at the edge of doped regions 230
6.4 Diffusion of non-doping materials 231
7 Cleaning technology 235
7.1 Contaminants and their effect 235
7.2 Clean rooms, clean materials and clean processes 239
7.2.1 Clean rooms 239
7.2.2 Clean materials 242
7.2.3 Clean processing 244
7.3 Wafer cleaning 244
8 Process integration 249
8.1 The various MOS and bipolar technologies 249
8.1.1 Active components in integrated circuits 249
8.1.2 Comparsion of MOS and bipolar technologies 249
8.1.3 Passive components in integrated circuits 252
8.2 Technology architecture 252
8.2.1 Architecture of MOS technology 252
8.2.2 Architecture of bipolar and BICMOS technologies 254
8.3 Transistors in integrated circuits 256
8.3.1 Design of MOS transistors and their isolation 256
8.3.2 Design of DMOS transistors 262
8.3.3 Design of bipolar transistors and their isolation 264
8.4 Memory cells 267
8.4.1 Design of static memory cells 267
8.4.2 Design of dynamic memory cells 269
8.4.3 Design of non-volatile memory cells 272
8.5 Multilayer metallization 276
8.5.1 Planarization of surfaces in integrated circuits 277
8.5.2 Contacts in integrated circuits 281
8.5.3 Metallization in integrated ciruits 284
8.5.4 Passivation of integrated circuits 285
8.6 Detailed process sequence of selected technologies 286
8.6.1 Digital CMOS process 286
8.6.2 BICMOS process 286
8.6.3 Microwave bipolar process 286
8.6.4 DRAM process 295
References 323
Subject Index 329
END
