The smaller wavelengths and wide frequency bands that can be allocated at 0.1 to 1 THz hold the promise for enabling radar imaging in visually impaired conditions with an angular resolution capability overlapping with that of lidars, and energy efficient Tbits/sec communication. The state of art of microelectronics in this frequency range that has rapidly advanced over the past decade is reviewed. Two application examples, 420-GHz imaging and 300-GHz high bandwidth wireless communication are used to motivate the IC technology innovation opportunities beyond that for the transistors. The list includes better optimization of the interconnect process, Schottky diodes and MOS varactors, and development of energy efficient passive gain structures, as well as co-integration of antennas and passives with packaging that may be more straightforward to implement and may also lead to superior performance. Enabling built-in self-testing is another innovation opportunity, which is also a necessity.