50 micron pitch wafer level packaging testbed with reworkable IC-package nano interconnects Conference

Aggarwal, AO, Raj, PM, Sundaram, V et al. (2005). 50 micron pitch wafer level packaging testbed with reworkable IC-package nano interconnects . 2 1139-1146.

cited authors

  • Aggarwal, AO; Raj, PM; Sundaram, V; Ravi, D; Koh, S; Mullapudi, R; Tummala, RR

authors

abstract

  • The decrease in feature sizes of micro-electronic devices has underlined the need for higher number of I/O's in order to increase its functionality. Being able to provide several fold increase in the chip-to-package vertical interconnect density is essential for garnering the true benefits of nanotechnology that will utilize nanoscale devices. This will spur greater interest in developing electronic packages with fine and ultra fine pitches (20-50 microns). Current approaches for chip to package interconnections are limited in terms of either pitch or electrical-mechanical trade-off in properties. For example, lead free solder interconnects fail mechanically as the pitch is brought down from current 200 micron pitch to 20 micron. Compliant leads, on the other hand, solve mechanical reliability but at the expense of electrical performance. We propose reworkable nano interconnects as a new interconnect paradigm for potential low cost, highest performance and reliability - not trading one for the other. This paper describes the design and fabrication of the first 50 micron pitch wafer level packaging test bed to demonstrate reworkable nano-interconnects. Nano-grained electroplated copper is chosen as the primary interconnect material. Reworkability was addressed by a thin, liquid lead-free solder interface between the interconnect and the package. The processing approaches for the electroplated Cu interconnect, Sn-Cu interface and the high-density substrate wiring are presented along with the simulated mechanical and electrical performance of the interconnects. © 2005 IEEE.

publication date

  • September 19, 2005

start page

  • 1139

end page

  • 1146

volume

  • 2