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FEA study of damage and cracking risks in BEoL structures under copper wirebonding impact

 
: Auersperg, J.; Breuer, D.; Machani, K.V; Rzepka, S.; Michel, B.

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Institute of Electrical and Electronics Engineers -IEEE-; IEEE Components, Packaging, and Manufacturing Technology Society:
16th International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems, EuroSimE 2015 : 19-22 April 2015, Budapest, Hungary
Piscataway, NJ: IEEE, 2015
ISBN: 978-1-4799-9949-1 (Print)
ISBN: 978-1-4799-9950-7
ISBN: 978-1-4799-9951-4
5 pp.
International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems (EuroSimE) <16, 2015, Budapest>
English
Conference Paper
Fraunhofer ENAS ()

Abstract
With the recent increase in Gold (Au) wire cost; Copper (Cu) wire becomes an attractive way to manage overall package cost. On the other hand, Copper wire bonding introduces much higher mechanical impact to underlying BEoLstructures and actives because of the higher stiffness and lower ductility of Copper compared to Gold. These trends are accompanied by the application of new porous or nano-particle filled materials like low-k and ultra low-k materials for Back-end of line (BEoL) layers of advanced CMOS technologies. As a result, higher delamination and cracking risks in BEoLstructures underneath bonded areas represent an increasing challenge for the thermo-mechanical reliability requirements. To overcome the related reliability issues the authors performed a two level nonlinear FEM-simulation approach. Initially nonlinear axisymmetric modeling and simulation of the copper bonding process are coupled with a spatial simulation model of the whole BeoL and bond pad structure. Cracking and delamination risks are estimated by a surface based cohesive contact approach and the utilization of a crushing foam constitutive material model for ultra low-k materials.

: http://publica.fraunhofer.de/documents/N-375011.html