Multi-layer inductor formed in a semiconductor substrate and having a core of ferromagnetic material

Abstract

A thin-film multilayer high-Q inductor having a ferromagnetic core and spanning at least three metal layers is formed by forming a plurality of parallel first metal runners on the semiconductor substrate. A plurality of first and second vertical conductive vias are formed in electrical connection with each end of the plurality of metal runners. A plurality of third and fourth conductive vias are formed over the plurality of first and second conductive vias and a plurality of second metal runners are formed interconnecting the plurality of third and fourth conductive vias. The first metal runners and second metal runners are oriented such that one end of a first metal runner is connected to an overlying end of a second metal runner by way of the first and third vertical conductive vias. The other end of the second metal runner is connected to the next metal one runner by way of the second and fourth vertical conductive vias., forming a continuously conductive structure having a generally helical shape. An inductor core is formed by first forming a silicon layer between each one of the plurality of first metal runners. A germanium layer is formed thereover and the structure is annealed, causing formation of quantum dots of germanium. A cobalt layer is then formed over the quantum dots and another anneal process drives the cobalt into the quantum dots, where it is captured to form the ferromagnetic core.