Revisiting Charge Trapping/Detrapping in Flash Memories From a Discrete and Statistical Standpoint—Part I: \(V_{T}\) Instabilities

Abstract

This paper and the corresponding Part II [1] revisit charge trapping and detrapping in Flash memories considering some major features of the phenomenon which have been clearly detected on nanoscale technologies: charge discreteness, statistical charge capture and emission, statistical distribution of the threshold-voltage shift following a charge capture/emission event, and spectral distribution of the detrapping time constants over many decades of time. In this Part I, we address threshold-voltage instabilities following charge detrapping from the cell tunnel oxide, highlighting their statistical properties and coming to a powerful formula for their quantitative analysis. These results pave the way to the development of a comprehensive statistical model able to deal with charge trapping/detrapping during whatever on-field array operation, representing the topic of Part II.