Gate-first high-k/metal gate DRAM technology for low power and high performance products

It is the first time that the high-k/metal gate technology was used at peripheral transistors for fully integrated and functioning DRAM. For cost effective DRAM technology, capping nitride spacer was used on cell bit-line scheme, and single work function metal gate was employed without strain technology. The threshold voltage was controlled by using single TiN metal gate with La2O3 and SiGe/Si epi technology. The optimized DRAM high-k/metal gate peripheral transistors showed current gains of 65%/55% and DIBL improvements of 52%/46% for nMOSFET and pMOSFET, respectively. The results in process yield, performance, and reliability characteristics of the technology on 4Gb DRAM have shown that the gate-first high-k/metal gate DRAM technology can be regarded as one of the major candidates for next-generation low power DRAM products.