D I S S E R T A T I O N

Advanced Methods
for Mechanical Analysis and Simulation of Through Silicon Vias

ausgeführt zum Zwecke der Erlangung des akademischen Grades
eines Doktors der technischen Wissenschaften

eingereicht an der Technischen Universität Wien
Fakultät für Elektrotechnik und Informationstechnik
von

Anderson Pires Singulani

Kleegasse 3/2.11, 8020 Graz, Österreich

geboren am 24. März 1984 in Rio de Janeiro, Brasilien

Wien, im Juni 2014

Abstract
Kurzfassung
Resumo
Acknowledgement
Contents
List of Figures
List of Tables
List of Abbreviations
List of Symbols
1  Introduction
 1.1  History of Device Integration Technology
 1.2  Limitations of the Current Technology
 1.3  Three-Dimensional Integration and TSVs
  1.3.1  Types of Three-Dimensional Integration
  1.3.2  TSV Fabrication
  1.3.3  Via First, Via Middle, and Via Last
 1.4  Challenges and Opportunities
 1.5  Outline of the Thesis
2  Mechanics in Microelectronics
 2.1  Mechanical Systems
 2.2  Mechanical Theory
  2.2.1  Infinitesimal Strain Theory
  2.2.2  Hooke’s Law
  2.2.3  Thermal Expansion
 2.3  Reliability
  2.3.1  Yield
  2.3.2  Yield Criteria
3  Simulation of Mechanical Systems
 3.1  Finite Element Method
  3.1.1  Variational Form
  3.1.2  Galerkin’s Method
  3.1.3  Discretization
  3.1.4  Basis Functions and Domain Partitioning
  3.1.5  Geometrical Interpretation of FEM
  3.1.6  Final Remarks on FEM
 3.2  Elasticity with FEM
 3.3  Time Dependent Problems
4  Mechanical Impact of TSVs in Silicon
 4.1  Properties of Interconnect Materials
 4.2  Design of TSVs
 4.3  Evaluating TSVs’ Mechanical Impact
  4.3.1  Thermo-mechanical Simulation of TSVs
  4.3.2  Analytic Solution for the Stress Around One TSV
  4.3.3  Stress in a Group of TSVs
  4.3.4  Summary and Conclusion
5  Stress Inside TSVs
 5.1  Stress in Thin Films of TSVs
 5.2  Influence of Stress in Metal Layers on TSVs
  5.2.1  Scallop Geometry
  5.2.2  Meshing and Boundary Conditions
  5.2.3  Simulation Results
  5.2.4  Summary and Conclusion
 5.3  Impact of Wafer Bow in TSVs
  5.3.1  Simulation of “Unbow” Wafer Movements
  5.3.2  Summary and Conclusion
 5.4  Strain Relaxation
  5.4.1  Strain Relaxation by Dislocation Glide
  5.4.2  Strain Relaxation Driven by Temperature
 5.5  Simulation of Stress Behavior in Thermal Cycles
  5.5.1  Model Parameters
  5.5.2  Coupling with FEM
  5.5.3  Summary and Conclusion
6  Residual Stress in TSVs
 6.1  Growth of Metal Films
 6.2  Residual Stress Formation
 6.3  Residual Stress Calculation of a Single Droplet
  6.3.1  Hoffman’s Model
  6.3.2  Nix-Clemens Model
  6.3.3  Freund-Chason Model
 6.4  FEM Calculations of Residual Stress in Single Droplets
 6.5  Residual Stress Estimation
  6.5.1  One-Dimensional Volmer-Weber Growth Simulation
  6.5.2  Coalescence Simulation
  6.5.3  Stress Estimate
  6.5.4  Summary and Conclusion
7  Summary and Outlook
A  Properties and Identities of First and Second Rank Tensors
Bibliography
List of Publications

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