RF CROSSTALK SUPPRESSION BASED ON WAFER-LEVEL PACKAGING CONCEPT
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
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.