In this paper, an overview of today's status and progress, as well as tomorrow's challenges and trends, in the field of advanced nonvolatile memories based on discrete traps is given. In particular, unique features of silicon nanocrystal and SONOS memories will be illustrated through original recent data. The main potentials and main issues of these technologies as candidates to push further the scaling limits of conventional floating-gate Flash devices will be evaluated.

No abstract

In this work, arrays of two transistor (2T) and compact SONOS memory cells are presented together with an extensive reliability investigation. SONOS, which acronym stands f o r semiconductor-oxide-nitride-oxidesemiconductor, is a non-volatile memory concept, which has recently regained strong attention because floating gate flash reaches its scaling limits. The better scaling perspective together with the ease of inregration in a base line CMOS process makes SONOS an excellent candidate for embedded flash in frrture CMOS generations. This is especially true f o r the compact cell variant. which consists of a merged access gate (AG) and control gate (CG), giving extra advantages like smaller cell size and the reduction of short channel effects compared with the discrete two transistor variant.

We have observed a high-temperature thermostimulated exoelectron emission from charged silicon nanocrystals with nitrided surface embedded into the amorphous SiO2 matrix. The developed Auger model allows understanding thermostimulated exoelectron emission origin and estimating energy activation of traps responsible for charge retention in this type of flash memory based on Si nanocrystals. The high activation energy Et of the electrons trapped in the nanocrystals confirms high potential of Si nanocrystal materials for fabrication of semiconductor memories with enhanced retention.