Institute of Microelectronics - Research Projects

This new title of project II.2 (instead of nanocrystal memories) is more representative of our last 2 year-activities

Project leader: Dr P. Normand
Key Researchers: Dr P. Normand, Dr V. Ioannou-Sougleridis
Post-doctorals: Dr D. Skarlatos, Dr V. Vamvakas
PhD candidates: P. Dimitrakis, E. Kapetanakis, S. Kolliopoulou
Main External Collaborators in 2005: Prof. D. Tsoukalas (NTUA), Dr C. Bonafos and Dr G. BenAssayag (CEMES/CNRS), Dr B. Schmidt (FZR), Dr M. Petty (Univ. Durham), Dr A. Nylandsted (Univ. Aarhus)

To develop novel high-throughput synthesis routes and techniques for creating nanoparticles in dielectrics, such as silicon nanocrystals in SiO2 films by low-energy ion-beam-synthesis.
To investigate the structural and electrical properties of the generated nanostructured materials and demonstrate material characteristics enabling the development of low-voltage high-density memory devices.
To realize and evaluate nanostructure-based-memory devices and assess the manufacturability of the developed nanofabrication routes in an industrial environment.

Research orientation:
By associating the finite-size effects (e.g. Coulomb blockade) of nanocrystals and the benefits (robustness and fault-tolerance) of a stored charge distribution, the nanocrystal memories (NCMs) offer an attractive alternative for extending the scaling of conventional floating-gate memories (e.g. Flash EEPROMs). Our activities in this area started in 1996 through the development of the low-energy ion-beam-synthesis (LE-IBS) technique for producing nanocrystals in thin gate dielectrics. In collaboration with the University of Salford and the University of Thessalonique, generation of a 2D-array of Si nanocrystals in SiO2 films by LE-IBS was demonstrated in 1997. This activity was further supported by the EU project, FASEM (1997-2000). LE-IBS Si-NCMs with endurance and write/erase times that approach those of DRAM were demonstrated in 1999. Observations of room-temperature single-electron storage effects in large-area n-channel Si-NC-MOSFETs were reported for the first time in 2002. Development of the LE-IBS technique with target the realization of manufactory non-volatile NCMs, has been conducted within the framework of the EU project, NEON (2001-2004), in collaboration with the US implanter manufacturer Axcelis.

In addition to our LE-IBS-NCM activities, major efforts have been devoted the last three years to the development of novel NCMs alternatives including, (a) Memory devices by Si+ irradiation through poly-Si/SiO2 gate stack in collaboration with Research Center Rossendorf and Zentrum Mikroelektronik Dresden, (b) Memory devices using Ge nanocrystals produced by molecular-beam epitaxy and rapid-thermal processing in collaboration with Aarhus University, (c) hybrid silicon-organic and SiGe-organic memories in collaboration with the University of Durham; this last activity was initiated within the framework of the EU IST-FET project, FRACTURE (2001-2003).

Low-voltage Si nanocrystal memories obtained by low-energy ion-beam-synthesis
Channel edge effects in shallow-trench-isolated nanocrystal memories
Hybrid SiGe/organic MOSFET with self-assembled Au-nps for memory applications
Oxide/nitride/oxide dielectric stacks with Si nanocrystals embedded in nitride

Specific targets for 2006 include: (a) Fabrication of Si NCs of controlled size and interspacing by block-copolymer-assisted-nanopatterning in collaboration with project I.1, (b) development of a novel Si-NC synthesis route based on plasma-immersion ion-implantation in collaboration with CEMES/CNRS and one French SME (Ion Beam Services), (c) formation of oxide/nitride/oxide dielectric stacks with Si-NCs embedded in the nitride layer by LE-IBS and LPCVD for achieving fast memory devices with improved non-volatility.