Patent ID: 9012996
Filing Date: 2015-04-21
Classification: H01L

Abstract:
1. A method of forming a silicon-on-insulator (SOI) radio-frequency (RF) device, comprising the following steps in the sequence set forth: providing a silicon substrate; forming a buried oxide layer on the silicon substrate; forming a device layer on the buried oxide layer, the device layer comprising an RF device; forming a first dielectric layer covering the device layer; forming a deep trench structure extending through, from the top downward, the first dielectric layer, the device layer and the buried oxide layer to an interface between the buried oxide layer and the silicon substrate; and forming a second dielectric layer covering both of the first dielectric layer and the deep trench structure, wherein forming the deep trench structure includes the steps of: etching the first dielectric layer, the device layer and the buried oxide layer until the interface between the buried oxide layer and the silicon substrate is reached to form a deep trench; filling polysilicon in the deep trench until the deep trench is completely filled with the polysilicon and a portion of the polysilicon is deposited over the first dielectric layer; and etching away the portion of the polysilicon over the first dielectric layer to form the deep trench structure such that a top surface of the deep trench structure is level with a top surface of the first dielectric layer.