A grounded body SOI (GBSOI) MOSFET has been proposed, fabricated and characterized to verify the applicability for high speed and low power VLSI circuits including digital and analog circuits.
The device that had a body tied to a grounded $p^+$ polysilicon layer buried under the channel region was realized by a wafer bonding and polishing technology.
The GBSOI device with a buried electrode eliminated body floating effects such as drain current kink and single transistor latch, and it increased drain breakdown voltage. An occurrence of drain current kink depending on the buried electrode resistance was monitored by connecting various external resistors to the $p^+$ polysilicon of the buried electrode. As a result, the kink effect was not observed for a buried electrode resistance below 100 kΩ. A significant damage in the gate oxide/silicon interface was not observed during the wafer bonding and polishing steps, which was confirmed by the measurement of interface trap density through the charge pumping and subthreshold current methods.
The proposed structure is proved to greatly improve the performances of SOI MOSFET by eliminating parasitic bipolar actions originated from the body floating.
