CRYOGENIC SEMICONDUCTOR DEVICE HAVING BURIED CHANNEL ARRAY TRANSISTOR

A cryogenic semiconductor device includes isolation regions defining an active region having a first P-type ion concentration in a substrate, a gate structure in the substrate, and an ion implantation region having a second P-type ion concentration in the active region below the gate structure, wherein the gate structure includes a gate dielectric layer conformally disposed on inner sidewalls of a gate trench, a lower gate electrode disposed on the gate dielectric layer, and an upper gate electrode disposed on the lower gate electrode, wherein the lower gate electrode has a relatively lower work function than the upper gate electrode.