Unlike some other technologies, FD-SOI does not change the fundamental geometry of the transistor. In FD-SOI, the innovation lies in adding a thin layer of insulator, called the buried oxide, positioned just below the channel—the UTBB. This buried oxide layer eliminates the need to add dopants to the channel, thus making it fully depleted.
This video explains some of the challenges of transistor design and how FD-SOI meets these challenges in a simple and cost-effective way today.