Patent ID: 7911014

Claim:
A method of improving the range of an antenna attached to a monolithic integrated circuit by reducing electromagnetic losses incurred in semiconductor substrate comprising the steps of: providing a semiconductor substrate having a top and bottom surfaces; forming a plurality of circuit elements that include active and passive components on the top surface of the semiconductor substrate; forming multilevel interconnects layers that include metal lines, vias, contacts, and insulators to interconnect among the circuit elements; forming an antenna with a top metallization layer, the antenna electrically coupled to at least one of the circuit elements, the antenna being spiral-shaped, and the antenna being laid out along the edges of a die that contains part of or all of the integrated circuit inside the antenna and a distance away from other parallel interconnects and circuit elements; forming proper grounding structures to reduce the electromagnetic interference between the antenna and the rest of the integrated circuit; forming an air-filled trench in the area directly underneath metal lines that made up the spiral-shaped antenna, the width of the trench being equal or larger than the width of all the metal lines that made up the antenna, the trench being formed by selectively etching the semiconductor substrate from its bottom surface to its top surface wherein the semiconductor substrate lying over a buried oxide and a handling semiconductor substrate; wherein additional steps of thinning down the handling semiconductor substrate, and of etching through the handling semiconductor substrate, the buried oxide, and the top semiconductor substrate to formed the air-filled trench.