Nitric Oxide Rapid Thermal Nitridation of Thin Gate Oxides

Abstract

Nitric oxide rapid thermal nitridation of thin gate oxides was investigated. Oxides from 25 to 55 A were grown in 02 and subsequently nitrided in a nitric oxide (NO) ambient using an Applied Materials RTP Centura chamber. Nitrogen incorporation and film thickness growth during NO nitridation were evaluated. Peak nitrogen incorporation was most strongly influenced by temperature and time, with moderate influence by initial oxide thickness, and no significant influence due to NO flow rate. Peak nitrogen concentrations ranged from 1 to 9 atomic percent as characterized by Secondary Ion Mass Spectrometry (SIMS) analysis. Oxide growth during nitridation ranged from 2 A to II A with no degradation in uniformity. These data were used in the design of two 40 A oxynitride processes incorporating 2 and 4 peak atomic percent nitrogen. High quality MOS capacitors were demonstrated with these dielectrics. Performance was compared against a baseline furnace process as well as non-nitrided RTO. Throughout this work, the chamber integrity was monitored using visual inspection, minority carrier lifetime (MCLT) and surface photovoltage (SPV). No contamination, corrosion or other degradation of the process chamber was observed in over 6 months' operation with over 700 NO processes completed. The controllability, uniformity and high nitrogen incorporation of rapid thermal NO nitridation make it an attractive process for deep sub-micron gate insulators.