Cratering on thermosonic copper wire ball bonding

  • Tan Chee Wei
  • Abdul Razak Daud
Article

Abstract

Copper wire bonding offers several mechanical and electrical advantages as well as cost saving compared to its gold wire predecessor. Despite these benefits, silicon cratering, which completes the fracture and removal of bond pad underlayers, has been a major hurdle to overcome in copper wire bonding. Copper wire is harder than gold, and thus needs greater ultrasonic power and bond force to bond it onto metal pads such as aluminum. This paper reports a study on the influence of wire materials, bond pad hardness, and bonding-machine parameters (i.e., ultrasonic power and bond force) on silicon cratering phenomenon. Ultrasonic power and z-axis bond force were identified as the most critical bonding machine parameters in silicon cratering defects. A combination of greater bond force and lower ultrasonic power avoids silicon cratering and gives the desired effects. Results also show that a harder bond pad provides relatively good protection from silicon cratering.

Keywords

bond force copper wire bonding silicon cratering ultrasonic power 

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Copyright information

© ASM International 2002

Authors and Affiliations

  • Tan Chee Wei
    • 1
  • Abdul Razak Daud
    • 2
  1. 1.ON Semiconductor, SCG Ind. (M) Sdn. Bhd., Senawang Industrial Estate, Seremban, Malaysia and School of Applied PhysicsUniversiti Kebangsaan MalaysiaBangi, Selangor Darul EhsanMalaysia
  2. 2.School of Applied PhysicsUniversiti Kebangsaan MalaysiaBangi, Selangor Darul EhsanMalaysia

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