SOI RF device and method for forming the same

摘要

A SOI RF device and a method for forming the same are provided. A trench exposed a part of the high resistivity silicon base is formed in the SOI substrate; a non-doped polysilicon layer is disposed on the high resistivity silicon base which is exposed by the trench; and at least a part of the non-doped polysilicon layer is covered by an above metal layer. With effects of the metal layer which is applied with a RF signal or a superposed signal, and fixed charges in the BOX layer, an inversion layer may be formed at a surface of the non-doped polysilicon layer. Since carriers may easily recombine at the grain boundaries of polysilicon, eddy current generated on a surface of the high resistivity silicon base is reduced, loss of the RF signal is reduced, and linearity of the RF signal device is improved.

主权项

1. A Silicon On Insulator (SOI) Radio Frequency (RF) device, comprising:
a SOI substrate, which comprises a high resistivity silicon base, a top silicon layer and a Buried Oxide (BOX) layer disposed between the high resistivity silicon base and the top silicon layer, where two or more active areas are disposed in the top silicon layer, each two adjacent active areas are insulated by a trench formed in the SOI substrate, the trench exposes a part of the high resistivity silicon base, the part of the high resistivity silicon base exposed by the trench is covered by a non-doped polysilicon layer which contacts the high resistivity silicon base, a part of the trench which is not filled with the non-doped polysilicon layer is filled with an insulation layer, and the insulation layer insulates the top silicon layer and the non-doped polysilicon layer; and a plurality of metal interconnection structures formed on the top silicon layer and the insulation layer, where each of the plurality of metal interconnection structures comprises an interlayer dielectric layer formed on the top silicon layer and the insulation layer, and a metal layer formed on the interlayer dielectric layer, and at least a part of the non-doped polysilicon layer is covered by the metal layer.