This paper presents the fabrication and the electrical characterization of poly-Si filled through-silicon vias, which were etched in a 180 µm thin silicon device wafer, bonded to a handle wafer by plasma activated oxide-to-silicon bonding. Heavily doped poly-Si was used as interconnection material, which was deposited by low-pressure chemical vapor deposition. Two different via geometries, i.e. stadium shaped, and circular shaped, were tried. Sputtered aluminum metallization layers as double-side redistribution lines and contact pads, were used. Both Kelvin structures and daisy chains were fabricated and their electrical resistances were measured. The electrical resistance of a single stadium-shaped via was measured to be about 24 Ω. The electrical resistance was varying from 60 Ω to 90 Ω for two-vias daisy chains. Measured results indicate that this via-first technology can be used for varying range of sensor applications like microphone, oscillator, resonator, etc where CMOS compatibility and high temperature processing are the prime requirements.
Dixit, P., Vehmas, T., Vähänen, S., Monnoyer, P., & Henttinen, K. (2012). Fabrication and electrical characterization of high aspect ratio poly-silicon filled through-silicon vias. Journal of Micromechanics and Microengineering, 22(5), . https://doi.org/10.1088/0960-1317/22/5/055021