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Contents
8.2.2 Random or Local Process Variability ................................ 287
8.2.2.1 Random Discrete Doping.................................... 287
8.2.2.2 Line-Edge Roughness .......................................... 290
8.2.2.3 Oxide Thickness Variation .................................. 290
8.2.2.4 Other Sources Process Variability ..................... 291
8.3 Characterization of Parametric Variability in MOSFETs ............ 291
8.3.1 Random Variability ............................................................. 291
8.3.2 Systematic Variability .......................................................... 293
8.4 Conventional Process Variability Modeling for Circuit CAD ....294
8.4.1 Worst-Case Fixed Corner Models ...................................... 294
8.4.2 Statistical Corner Models .................................................... 296
8.4.3 Process Parameters–Based Compact Variability
Modeling ............................................................................... 296
8.5 Statistical Compact Modeling ......................................................... 297
8.5.1 Determination of Process Variability-Sensitive
MOSFET Device Parameters .............................................. 298
8.5.1.1 Selection of Local Process
Variability- Sensitive Device Parameters .......... 298
8.5.1.2 Selection of Global Process
Variability- Sensitive Device Parameters .......... 299
8.5.2 Mapping Process Variability-Sensitive
Device Parameters to Compact Model Parameters ......... 301
8.5.2.1 Mapping Local Process Variability-Sensitive
Device Parameters to Compact Model
Parameters ............................................................. 301
8.5.2.2 Mapping Global Process
Variability- Sensitive Device Parameters
to Compact Model Parameters ........................... 302
8.5.3 Determination of Variance for
Process Variability-Sensitive Compact Model
Parameters ............................................................................ 303
8.5.3.1 Variance of Local Process
Variability-Sensitive Compact Model
Parameters ............................................................. 303
8.5.3.2 Variance of the Global Process
Variability- Sensitive Compact Model
Parameters .............................................................304
8.5.4 Formulation of Compact Model for Process
Variability-Aware Circuit Design ......................................304
8.5.5 Simulation Results and Discussions .................................308
8.6 Mitigation of the Risk of Process Variability in VLSI Circuit
Performance ....................................................................................... 309
8.7 Summary ............................................................................................ 311
Exercises ........................................................................................................ 311