spezielle anwendungen des vlsi – entwurfs applied vlsi design
DESCRIPTION
Spezielle Anwendungen des VLSI – Entwurfs Applied VLSI design. Phase 5 Reliability - Electromigration Robert Mars. Metal wire. Thickness fixed by process parameters Width can be adapted by designer. Metal r eliability. Blacks´s Equation: lifetime of an interconnect scales with and - PowerPoint PPT PresentationTRANSCRIPT
Institute of Applied Microelectronics and Computer Engineering
College of Computer Science and Electrical Engineering, University of Rostock Slide 1
Spezielle Anwendungen des VLSI – Entwurfs
Applied VLSI design
Phase 5
Reliability - Electromigration
Robert Mars
Institute of Applied Microelectronics and Computer Engineering
College of Computer Science and Electrical Engineering, University of Rostock
Metal wire
• Thickness fixed by process parameters
• Width can be adapted by designer
Slide 2
width
height
length
Institute of Applied Microelectronics and Computer Engineering
College of Computer Science and Electrical Engineering, University of Rostock
Metal reliabilityBlacks´s Equation: lifetime of an interconnect scales with and
Source: ITRS (International Technology Roadmap for Semiconductors) 2011
Slide 3
2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 20260
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
Year
Cu
rre
nt
de
ns
ity
(M
A/c
m²)
Institute of Applied Microelectronics and Computer Engineering
College of Computer Science and Electrical Engineering, University of Rostock
Metal reliability
Slide 4
Growth of voids
Increase in current density
Increase in temperature
Increase in Joule heating
Institute of Applied Microelectronics and Computer Engineering
College of Computer Science and Electrical Engineering, University of Rostock
Electromigration
• Metal ions move towards the anode• Force on ions due to electron scattering in direction of electron flow• Electric field in metal causes electrostatic force on ions• Damage caused by divergences in atomic flux
Slide 5
Institute of Applied Microelectronics and Computer Engineering
College of Computer Science and Electrical Engineering, University of Rostock
Enhancing reliability• Wire Widening
increasing cross-section area• Passivation Layer
prevent diffusion, better dissipation of joule heat• Gold Metallizations
very high activation energy• Alloying of Metallization
addition of Ti-Si or Cu to Al• Deposition Techniques
i.e. MTTF smaller for Sputtering than electron-beam deposition• Wire length
if wire is shorter than Blech length mechanical stress compensates material flow
Slide 6
Institute of Applied Microelectronics and Computer Engineering
College of Computer Science and Electrical Engineering, University of Rostock
Thank you for your attention
Slide 7
Institute of Applied Microelectronics and Computer Engineering
College of Computer Science and Electrical Engineering, University of Rostock
Quellen
• http://www.synopsys.com/Tools/Verification/CapsuleModule/CustomSim-RA-wp.pdf
• http://www.doitpoms.ac.uk/tlplib/electromigration/index.php• http://www.ece.mtu.edu/faculty/goel/EE-4271/Web-Interconnects.pdf
Slide 8
Institute of Applied Microelectronics and Computer Engineering
College of Computer Science and Electrical Engineering, University of Rostock
Stresses
Slide 9
Institute of Applied Microelectronics and Computer Engineering
College of Computer Science and Electrical Engineering, University of Rostock
Jmax Calculation
Quelle: http://www.itrs.net/Links/2011ITRS/2011Chapters/2011Interconnect.pdf
Slide 10
Institute of Applied Microelectronics and Computer Engineering
College of Computer Science and Electrical Engineering, University of Rostock
Blech length
– activation volume (m³)
– hydrostatic component of mechanical stress (kg m-1 s-2)
– electromigration force, which causes atomic migration
- effective valence (represents the sign and the magnitude of the momentum exchange)
– resistivity (
Slide 11