Investigation of charge loss mechanism of thickness-scalable trapping layer by variable temperature Kelvin probe force microscopy

Abstract

In this letter, the retention properties of charge trapping memory with decreased thickness of ultra-thin HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> charge trapping layer are investigated by Kelvin probe force microscopy (KFM) technology. Experiment results show that retention properties became worse with the reducing of HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> thickness and increasing of temperature. Based on total remaining charge density and lateral leakage charge density extracted from the contact potential differences, we find that vertical charge leakage acted as a dominant role of charge loss with respect to lateral charge redistribution. Furthermore, effective trap energies are extracted from KFM analysis at high temperatures and it is concluded that the suppression of lateral charge redistribution in thinner HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> layer results from deeper trap energies.