Distinguishing between oxygen and silicon atoms

Atom-selective imaging and mechanical atom manipulation using the non-contact atomic force microscope AFM; Oxford journals



.....Further, based on the NC-AFM method but using soft nanoindentation, we achieved two kinds of mechanical vertical manipulation of individual atoms: removal of a selected Si adatom and deposition of a Si atom into a selected Si adatom vacancy on the Si(111)7 × 7 surface at 78 K. Here, we carefully and slowly indented a Si atom on top of a clean Si tip apex onto a predetermined Si adatom to remove the targeted Si adatom and onto a predetermined Si adatom vacancy to deposit a Si atom, i.e. to repair the targeted Si adatom vacancy. By combining the atom-selective imaging method with two kinds of mechanical atom manipulation, i.e. by picking up a selected atom species and by depositing that atom one by one at the assigned site, we hope to construct nanomaterials and nanodevices made from more than two kinds of atom species in the near future.

www.oxfordjournals.org



Silicon Nano Crystal Memory Cell


Silicon Nano Crystal Memory Cell, where nano-crystals (NCs) are embedded in gate oxide and act as charge storages, has attracted much attention [ I ] . Physical separation of NCs can improve the retention time by limiting the lateral flow of charge. Thus, many efforts have been directed to explore the suitability as integrated-memory. However, the scaling of NCM cell is difficult without lithography advances or effective design with highly scalable process, because it is hard to reduce memory cell area per bit. To realize over gigabitdensity integration, NCM cell should be dramatically shrunk by introducing highly scalable self-aligned BLs contact. On the other hand, the reliability of NCM is also the critical issue. In an exploration of relationship of NCs controllability with the chemical nature and physical properties of tunelling dielectrics such as stress or roughness, it is essential t0 overcome reliability degradation effectively.

This paper reports the first full process integration of nano-crystal memory (NCM) with 4.6F2 cell (size: 0.0777pm2) based on NOR type, which is achieved by landing plug polysilicon contact (LPC) and direct tungsten (W) bitline (BL). Robust 4-threshold voltage (VT) states for 2bits operation per cell are verified Also, the
comparable characteristics to NCM with conventional silicide BL contact are obtained and NCM reliability is significantly improved by properly fluorinated effect while still keeping process compatibility and controllability, which is the only alternative for volume manufachue of high density NCM.

Integration of Fluorinated Nano-Crystal Memory Cells with 4.6F2 Size by Landing Plug Polysilicon Contact and Direct-Tungsten Bitline; www.google.co.uk