IWLPC (Wafer-Level Packaging) Conference Proceedings


Authors: S.M. Sinaga, A. Polyakov, M. Bartek, and J.N. Burg
Company: Laboratory of High Frequency Technology and Compon
Date Published: 11/1/2006   Conference: IWLPC (Wafer-Level Packaging)

Abstract: In this paper, new through-substrate trenching schemes for radio-frequency (RF) substrate crosstalk suppression are introduced. Wafer-level chip-scale packaging (WLCSP) technology, in which the active silicon substrate is bonded to a low-loss supporting substrate for maintaining mechanical integrity, is employed. Air-filled trenches are primarily useful at low RF, at which they effectively block low-frequency parasitic signals. At high RF the crosstalk signals propagate more easily across such trench barriers, which simply feature a locally minimized permittivity. Providing a grounded metal within the trench provides a means of draining the signal to ground besides blocking it. At 10GHz such a grounded trench gives an isolation that is ~40dB better than that of a control reference structure, while with the air trench only ~10dB improvement is achieved. The effectiveness of the grounded trench depends on the minimization of the parasitic impedance between the metal in the trench and the physical ground potential.

Key words: Isolation, substrate coupling, wafer-level packaging, trench.

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