Vertically scaled, high reliability EEPROM devices with ultra-thin oxynitride films prepared by RTP in N/sub 2/O/O/sub 2/ ambient

Vertical scaling of FLOTOX EEPROM cells for producing high density, low voltage programmable, reliable memories is achieved by thinning the tunnel insulator in the EEPROM cell. Factors which limit scaling of tunnel oxides, such as program-erase cycling induced leakage current, are examined in detail for insulators in the practical thickness range of 60-90 AA. We have also developed a new RTP oxynitridation process using gas mixtures of O/sub 2/ and N/sub 2/O, providing us robust ultra-thin tunnel insulators. The performance of memory cells fabricated with tunnel dielectrics using conventional, furnace grown, dry thermal oxides and the new RTP oxynitridation process are compared. The latter group of devices are found to have superior retention, endurance and programming characteristics. We demonstrate that the scalability of the cell is improved by using the oxynitride tunnel films.<>