Patent attributes
An antenna with air-filled trench is integrated with a radio frequency (RF) circuit. The trench locates directly under the metal lines that made up the antenna and is formed by etching from the back side of the semiconductor substrate until all the substrate material in the trench is removed. The air-filled trench greatly reduces the losses due to the semiconductor substrate; therefore the performance of the antenna improves greatly. When the antenna is a large planar spiral inductor, the air-filled trench means the semiconductor substrate inside the spiral inductor is untouched; hence integrated circuit can be built inside the antenna and on that substrate. Therefore the RF integrated circuit has a smaller size. Air-filled trench can also be used to reduce the semiconductor substrate noise coupling between digital circuit block and analog/RF circuit block. This air-filled trench and the air-filled trench under the antenna are formed at the same time.
