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.