An alpha immune and ultra low neutron SER high density SRAM

Terrestrial radiations, such as neutrons or alpha, create charges which, when collected by sensitive memory nodes, can destroy its stored information. Such a failure is called a soft error since only the data is destroyed while the circuit itself is not permanently damaged. Today, as the dimensions and operating voltages of semiconductor devices are continually reduced, the intrinsic SRAM sensitivity to ionizing radiations significantly increases. Whereas there is a linear and moderate increase on a per Mbit basis, the system SER significantly grows up together with the amount of SRAMs embedded in the chips. To meet the increasing need for both robust and highly integrated SRAMs, an original 3D memory device has been developed mixing SRAM and eDRAM capacitors. This memory cell, named rSRAM™ cell (r standing for robust), has been validated through a testchip manufactured in a standard 120 nm CMOS technology.