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Approaching the limit of the SiO2 possibilities for application in nanoscale microelectronics

N. NOVKOVSKI1,* , E. ATANASSOVA2

Affiliation

  1. nstitute of Physics, Faculty of Natural Sciences and Mathematics, P.O.Box 162, Skopje, 1000, Macedonia
  2. Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee blvd., Sofia, 1784, Bulgaria

Abstract

Silicon dioxide insulating layers play crucial role in the functioning of the contemporary microelectronic devices. The incessant increase of the integration level requires appropriate decreasing of the dimensions of all of the layers. That scaling affects mostly the ultrathin insulating layers with thicknesses approaching now the value of 1 nm, by exposing them to enormous electric fields, reaching the values of order of 109 V/m = 1 V/nm. The above high fields produce enormous leakage currents through these insulating layers, owing to different mechanisms, and cause rapid wear-out of the layers leading to their final destruction or loose of the insulating properties. For thicker films the high leakage is a result of the degradation during the fabrication or wear-out during the functioning, while for the extremely thin films (1 nm) fundamental mechanisms like direct tunneling take place. In the present paper our results are presented concerning the improvements of the properties of the insulating films, as well as the possible alternative technologies to obtain insulating films with better quality. The physical mechanisms of thus obtained improvements are explained, in order to benefit at most from technological solutions and find the directions for the further research in the corresponding technologies. Three types of technological solutions are discussed: a) Nitridation of the silicon dioxide layer or growth of an Si-oxynitride layer (SiO2 and SiOxNy layers); b) Growth of a layer of high permittivity (high-k) on silicon, specifically Ta2O5 (Ta2O5/SiO2 stacked layers) and c) Nitridation of the silicon prior to the Ta2O5 deposition, (Ta2O5/SiOxNy stacked layers). Though the additional technological steps and layers give striking improvements of the dielectric properties, the exceptional properties of the SiO2 play important role in the conduction mechanisms ensuring the acceptable leakage currents for new generations of integrated microelectronic circuits..

Keywords

Ultra-thin insulating films, Reliability, High-k dielectrics.

Submitted at: April 10, 2006
Accepted at: May 18, 2006

Citation

N. NOVKOVSKI, E. ATANASSOVA, Approaching the limit of the SiO2 possibilities for application in nanoscale microelectronics, Journal of Optoelectronics and Advanced Materials Vol. 8, Iss. 3, pp. 1238-1242 (2006)