Interconnects for a multi-layer three-dimensional silicon architecture

As low cost and low volume gain increasing importance in today's technology market, the development of lateral and vertical interconnects for K- through W-band applications using silicon micromachining is a worthwhile endeavor. Thus, lateral components appropriate for multi-layer applications, such as Wilkinson dividers, reactive tees and right angle bends, have been developed at 94 GHz. Wafer-to-wafer interconnects with only 0.1 dB insertion loss have also been developed in addition to vertical through-wafer interconnects with 0.5 dB insertion loss at 94 GHz. These components are integrated into a multi-layer silicon, micromachined power cube, 6 mm in length, 6 mm in width, 1 mm in height, that represents the first W-band (94 GHz) transmit module to date. The multi-layer silicon environment, with appropriate design and packaging, yields a solution to the low power problems of conventional monolithic microwave integrated circuits (MMIC) by providing more power per unit area. This article presents details of the passive components and interconnects involved for a 94 GHz design, although they may also be applied to lower frequencies.