THE DOUBLE-SIDED RUGGED POLY SI (DSR) TECHNOLOGY FOR HIGH-DENSITY DRAMS

The Double-Sided Rugged poly Si (DSR) technology has been developed fo r high density DRAMs. The DSR technology was achieved using transforma tion of rugged poly Si caused by ion implantation. The DSR can increas e the surface area of the storage electrode, because it has rugged sur faces on both upper and lower sides. The 2-FINs STC (STacked Capacitor cell) with DSR was fabricated in the cell size of 0.72 mu m(2), and i t is confirmed that the DSR can increase the surface area 1.8 times la rger than that of smooth poly Si. It is expected that 25 fF/bit is obt ained with a 300 nm-thick storage electrode. These effects show that s ufficient capacitance for 256 Mb DRAMs is obtained with a low storage electrode. It is confirmed that there is no degradation in C-V and I-V characteristics. Moreover, the DSR needs neither complicated process steps nor special technologies. Therefore, the DSR technology is one o f the most suitable methods for 256 Mb DRAMs and beyond.