Patent ID: 9214378
Filing Date: 2015-12-15
Classification: H01L

Abstract:
1. A method of making a silicon-on-insulator (SOI) semiconductor device, comprising: etching an undercut isolation trench into an SOI substrate, the SOI substrate comprising a bottom substrate, a buried oxide (BOX) layer formed on the bottom substrate, and a top SOI layer formed on the BOX layer, wherein the undercut isolation trench extends through the top SOI layer and the BOX layer and into the bottom substrate such that a portion of the undercut isolation trench is located in the bottom substrate underneath the BOX layer and has a widened lower portion with respect to an upper portion such that the widened lower portion is disposed directly below the BOX layer; completely filling the undercut isolation trench with an undercut fill entirely comprising an insulating material to form an undercut isolation region that isolates active areas of the top SOI layer from one another; forming a field effect transistor (FET) device on the top SOI layer adjacent to the undercut isolation region, wherein the undercut isolation region with the widened lower portion filled entirely with the insulating material extends underneath a source/drain region of the FET; and forming a source/drain contact to the source/drain region of the FET, wherein the source/drain contact has a portion disposed above a top surface of the source/drain region, and also extends into the undercut isolation region and below a bottom surface of the BOX layer, and wherein the source/drain contact is separated from the bottom substrate by the undercut fill so as to prevent shorting between the source/drain contact and the bottom substrate.