November 21, 2014, anysilicon
Fully Depleted Silicon On Insulator, or FD-SOI, is a planar process technology that relies on two primary innovations. First, an ultra-thin layer of insulator, called the buried oxide, is positioned on top of the base silicon.
Then, a very thin silicon film implements the transistor channel. Thanks to its thinness, there is no need to dope the channel, thus making the transistor Fully Depleted.
The combination of these two innovations is called “ultra-thin body and buried oxide Fully Depleted SOI” or UTBB-FD-SOI.
By construction, FD-SOI enables much better transistor electrostatic characteristics versus conventional bulk technology. The buried oxide layer lowers the parasitic capacitance between the source and the drain. It also efficiently confines the electrons flowing from the source to the drain, dramatically reducing performance-degrading leakage currents. (source: ST)