Yong-woo Hyung

Development and Optimization of Re-Oxidized Tunnel Oxide with Nitrogen Incorporation for the Flash Memory Applications

The reliability properties of NOR flash memory with 65nm node being developed in Samsung electronics are greatly improved by using the newly proposed re-oxidized tunnel oxide. Especially, by optimizing the process variables such as the re-oxidation thickness/time, the partial pressure of NO during annealing, and the kinds of re-oxidizing materials, the Vth shifts post cycling and after post-cycling bake were decreased to the level of 28% and 42% of conventional NO annealed tunnel oxide, respectively.

Ge Implantation to Improve Crystallinity and Productivity for Solid Phase Epitaxy Prepared by Atomic Mass Unit Cross Contamination-Free Technique

Germanium (Ge) ion implantation was investigated for crystallinity enhancement during solid phase epitaxial (SPE) regrowth. Electron back-scatter diffraction (EBSD) measurement showed numerical increase of 19% of (100) signal, which might be due to the effect of pre-amorphization implantation (PAI) on silicon layer. On the other hand, electrical property such as off-leakage current of n-channel metal oxide semiconductor (NMOS) transistor degraded in specific regions of wafers. It was confirmed that arsenic (As) atoms were incorporated into channel area during Ge ion implantation. Since the equipment for Ge PAI was using several source gases such as BF3 and AsH3, atomic mass unit (AMU) contamination during PAI of Ge with AMU 74 caused the incorporation of As with AMU 75 which resided in arc-chamber and other parts of the equipment. It was effective to use Ge isotope of AMU 72 to suppress AMU contamination. It was effective to use enriched Ge source gas with AMU 72 in order to improve productivity.