C4F8O/O2/N-BASED ADDITIVE GASES FOR SILICON NITRIDE PLASMA ENHANCED CHEMICAL VAPOR DEPOSITION CHAMBER CLEANING WITH LOW GLOBAL WARMING POTENTIALS

N2O and NO were added as additive gases to C4F8O/O2 for PECVD Si3N4 chamber cleaning and their effects on the emission properties of perfluorocarbon compounds (PFCs) were investigated. The cleaning rate, destruction and removal efficiencies, and million metric tons of C equivalent (MMTCE) were studied as a function of flow rates of PFCs and additive gases. The use of C4F8O/O2 alone showed the highest cleaning rate and the lowest emission properties at the cleaning condition of 20%C4F8O/80%O2, working pressure of 500 mTorr, and 13.56 MHz rf power of 350 W. By the addition of about 20% NO or 20% N2O to the optimized C4F8O/O2, the additional reduction of MMTCE higher than 50% could be obtained. The addition of NO resulted in lower MMTCE compared to that in the case of the addition of N2O mostly due to the higher Si3N4 cleaning rate in the latter case. 17 refs.