Master-slice 3D MMIC

NTT has developed a novel Master-Slice three-dimensional MMIC technology involving the masterslice concept in the 3D MMIC structure. This technology enables the fabrication of high-density, microwave and millimeter-wave semicustom MMICs that was unsuccessful in conventional planar MMICs. Areas of around 2 × 2 mm, each of which has transistors, resistors and capacitor electrodes closely located, are fabricated in advance over a masterslice wafer, and each area is selectively covered by ground metal to create a space wide enough for the 3D circuits stacked above it. Using this methodology, we achieved a turn-around-time half that of conventional MMICs. This technology is also applied successfully to low-cost Si wafers. Hence, the technology shows excellent potential for more widespread application of MMICs.