Electric bidirectional stress effects on metal–oxide–silicon capacitors

Abstract

Bidirectional electron injections were performed in thick and thin oxides of metal–oxide–silicon capacitors under a constant oxide electric field. Results show that dissymmetry, due to electron trapping near both oxide interfaces, is accentuated when the oxide is thin. However electron trapping is more marked when oxide is thick. Two kinds of thick oxide were used: wet and dry technologies. Wet oxide contains relatively more defects than dry. This is due to hydrogen incorporation in wet oxide during the oxidation process. But this difference is not well marked, because boron atoms injected after the oxidation process would deactivate hydrogen atoms. We describe the electron trapping by a well-known power law. The exponent of this law depends on oxide field polarity and also on oxide thickness but is technology independent. Results also show a nonexpecting behavior of tunneling current during bidirectional stress at a constant voltage. Here, we describe its causes and effects.

Carrier Storage in Ge Nanocrystals Grown on Silicon Oxide by a Two Step Dewetting / Nucleation Process

“…Let us note that the use of the Fowler-Nordheim tunnelling standard expression can qualitatively lead to determine the density of the carriers trapped in Ge-NCs, or at least it can inform on the trapping efficiency versus the temperature. This approach was previously made in the case of the standard MOS capacitor (DiMaria et al, 1993;El Hdiy & Ziane, 2001) to extract the trapped charge density from I-V measurements. We carefully use it according to the following assumptions: (a) there is no trapped carriers in the oxide, or the eventual stored carriers do not affect the initial oxide field E 0 , (b) the charge contained in the NCs is supposed to be distributed in a thin layer at the NC/oxide interface and (c) the supplementary field caused by the carrier storage process remains lower than E 0 .…”