title: Novel First-Level Interconnect Techniques for Flip Chip on MEMS Devices.
abstract: Flip-chip packaging is desirable for microelectro-mechanical systems (MEMS) devices because it reduces the overall package size and allows scaling up the number of MEMS chips through 3-D stacks. In this report, we demonstrate three novel techniques to create first-level interconnect (FLI) on MEMS: 1) Dip and attach technology for Ag epoxy; 2) Dispense technology for solder paste; 3) Dispense, pull, and attach technology (DPAT) for solder paste. The above techniques required no additional microfabrication steps, produced no visible surface contamination on the MEMS active structures, and generated high-aspect-ratio interconnects. The developed FLIs were successfully tested on MEMS moveable microelectrodes microfabricated by SUMMiTVTMprocess producing no apparent detrimental effect due to outgassing. The bumping processes were successfully applied on Al-deposited bond pads of 100μm×100μm with an average bump height of 101.3μm for Ag and 184.8μm for solder (63Sn, 37Pb). DPAT for solder paste produced bumps with the aspect ratio of 1.8 or more. The average shear strengths of Ag and solder bumps were 78 MPa and 689 kPa, respectively. The electrical test on Ag bumps at 794 A/cm2demonstrated reliable electrical interconnects with negligible resistance. These scalable FLI technologies are potentially useful for MEMS flip-chip packaging and 3-D stacking.
authors: School of Biological and Health Systems Engineering, Arizona State University, Tempe, AZ 85287-9709 USA.
authors: Jemmy
authors: J
authors: Sutanto
authors: School of Biological and Health Systems Engineering, Arizona State University, Tempe, AZ 85287-9709 USA.
authors: Sindhu
authors: S
authors: Anand
authors: School of Biological and Health Systems Engineering, Arizona State University, Tempe, AZ 85287-9709 USA.
authors: Chetan
authors: C
authors: Patel
authors: School of Biological and Health Systems Engineering, Arizona State University, Tempe, AZ 85287-9709 USA.
authors: Jit
authors: J
authors: Muthuswamy
keywords: 3-D stacks; BioMEMS; flip chip; flux contamination; interconnects; microchip; packaging; solder