THIN FLUORINATED GATE DIELECTRICS GROWN BY RAPID THERMAL-PROCESSING IN O2 WITH DILUTED NF3

This paper reports the application of rapid thermal processing (RTP) to the fabrication of ultrathin (approximately 10 nm) high-quality fluorinated oxides in O2 + NF3 (100 ppm diluted in N2). NF3 was used as F source gas and was introduced either prior to rapid thermal oxidation (RTO) or with O2 during the initial stage of RTO. The oxidation rate is enhanced because of the presence of NF3. In addition, F depth profiles in fluorinated oxides are dependent upon the process conditions. The electrical characteristics of MOS capacitors have been studied and correlated with the chemical properties. The initial interface state density (D(it)) is found to decrease with F incorporation. Both the amount of F and its depth profiles determine the hot-electron and radiation immunity of resulting fluorinated oxides. Excessive amount of F incorporation enhances the generation of positive charges and interface states during the stress. It is speculated that F not only terminates some Si dangling bonds, but also creates defects such as nonbridging oxygen centers and/or oxygen deficiencies which act as fixed charges, the precursors of interface states, and hole traps during hot-electron injection or irradiation.