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This paper presents design, fabrication, and high-frequency characterization of through-silicon-vias (TSVs) with benzocyclobutene (BCB) as the dielectric liner to exploit its low dielectric constant. Fabrication processes for BCB polymer liner TSVs are developed, and BCB-liner TSVs have been successfully fabricated in both low-resistivity silicon and high-resistivity silicon substrates for comparison. A de-embedding method that enables extraction of S-parameters from cascade TSV chains is developed based on the thru-reflect-line calibration algorithm, and the S-parameters of BCB-liner TSVs have been obtained from the measured transmission properties of cascade TSV chains with frequencies up to 25 GHz. Measurement results show that the BCB liner improves transmission properties of TSVs up to 10 GHz compared with SiO2-liner TSVs, and sub-strate resistivity dominates transmission properties for frequencies higher than 10 GHz. [ABSTRACT FROM AUTHOR]

The use of air gaps instead of SiO2 as insulators for through-silicon vias (TSVs) has been demonstrated to reduce the thermal stresses and the TSV capacitance of a 3-D integrated system. However, since the Cu plug in air-gap TSVs lacks support and fixation at the sidewalls, the mechanical strength is a serious concern. This paper for the first time reports the mechanical and humidity reliabilities of air-gap TSVs. Reliability tests including free drop test, vibration test, and accelerated moisture test are performed, and the failure mechanisms are analyzed. The residual stresses in silicon substrates are also measured using micro-Raman Spectroscopy. Experimental results show that the premetal dielectric that acts as the only support for Cu plugs is the weak point causing mechanical reliability issues, and oxidation of Cu plugs at high moisture and high temperature is the main reason for humidity reliability problems. Multilayer bonding of TSV chips to constitute a 3-D system remarkably increases the mechanical and humidity reliabilities of air-gap TSVs because of the support and protection provided by the bonding chips. [ABSTRACT FROM AUTHOR]

In this paper, the development of an innovative micro-coaxial line technology is presented and developed for dc-to-millimeter-wave broadband applications. This nondispersive line is fabricated using a simple photoimageable thick-film process. Wave-guiding properties of the developed micro-coaxial line are extracted from 1 to 110 GHz, showing an extremely broadband operation. A single transition from micro-coaxial line to grounded coplanar waveguide is used to cover the entire frequency range available through single vector network analyzer. Passive devices are then demonstrated in the form of a 60 GHz band-pass filter and an 8 dB coupler using vertically coupled lines. Measured results of the demonstrative filter show an excellent agreement with simulated results, which present very good performances with 1.5 dB insertion loss over the frequency band of interest. The broadband coupler exhibits an exceptional multioctave bandwidth (from 20 to 82 GHz) and low loss at 1.5 dB. [ABSTRACT FROM PUBLISHER]