RELIABILITY OF NITRIDED WET SILICON DIOXIDE THIN-FILMS IN WSI2 OR TASI2 POLYCIDE PROCESS - INFLUENCE OF THE NITRIDATION TEMPERATURE

In this paper it is investigated the influence of two polycide process es using WSi2 chemical vapor deposition (CVD) or TaSi2 deposition by s puttering on the integrity of wet and nitrided tunnel oxides (t(OX) = 6.6 nm) used in Electrical Erasable Programmable Read Only Memory (EEP ROM) under negative Fowler-Nordheim electron injection (FNEI). It was confirmed that the nitridation reduces the generation rates of defects created by FNEI (interface states, neutral traps, positive and negati ve charges) and the stress induced leakage current (SILC). This reduct ion is more pronounced when TaSi2 is used rather than WSi2. In sputter ing TaSi2 process compared to the CVD WSi2 one, it was observed : (i) - the generation of positive charges and the SILC are higher while the generation rates of interface states and negative charges are smaller ; (ii) - the generation rate of neutral traps is higher in wet oxide w hile it is smaller in nitrided oxides. Whatever the polycide process, the generation of the different types of defects created by FNEI is re duced by increasing the nitridation temperature while the SILC is incr eased. (C) 1998 Elsevier Science Ltd. All rights reserved.