Curing of 1-Transistor-DRAM by Joule Heat From Punch-Through Current

Abstract

The 1-transistor-DRAM (1T-DRAM) with a floating body is iteratively operated and deteriorated as the number of programming cycles is increased. This aging results an increase in the interface trap density ( Nit) . Internal electro-thermal annealing (ETA) using Joule heat generated by punch-through current flowing from the source via the channel to the drain, reduces the Nit and eventually cures the operating damage of the 1T-DRAM. To quantitatively analyze the Nit before and after curing, a synchronized optical charge pumping (SOCP) method that is applicable even to a floating body (FB) device, was used. By adopting self-curing during 1T-DRAM operations, endurance was notably increased by reducing Nit . It is expected that aged 1T-DRAMs can be recovered when such ETA is enabled at the moment of system rebooting.