High electric field induced positive charges in thin gate oxide

By means of capacitance-voltage technique the positive charging of 9 nm thi ck silicon dioxide after both positive and negative bias Fowler-Nordheim in jection has been evaluated. Measurement results allow to distinguish betwee n two types of positive charge depending on their response to gate voltage variation, i.e. trapped holes (TH) and anomalous positive charge (APC). The se two types of positive charges also show a different location in the oxid e. More precisely, TH are characteristic traps of the SiO2/Si interface and can be found only after negative bias stress, while APC are present in bot h cathodic and anodic oxide regions independently on the stress polarity. ( C) 2001 Elsevier Science Ltd All rights reserved.