TEMPERATURE-DEPENDENCE OF THE ETCH RATE AND SELECTIVITY OF SILICON-NITRIDE OVER SILICON DIOXIDE IN REMOTE PLASMA NF3 CL-2/

The etch rates and selectivity of Si3N4 over SiO2 have been investigat ed by microwave discharging a mixture of NF3 and Cl-2 and flowing the resultant fluorine and chlorine atoms and interhalogenous molecules si multaneously over a silicon wafer covered with low pressure chemical v apor deposition (LPCVD) Si3N4, and a wafer covered with thermally grow n SiO2. The temperature dependence of the etch rates of Si3N4 and SiO2 in the NF3/Cl-2 mixture was examined in the range from 25 to 500 degr ees C, and the selectivity of the nitride etch over the oxide etch as well as nitride etch rate was found to increase with increasing temper ature. It was also found that both etch rates and selectivities increa se with NF3 flow rates within the range used in this study. (C) 1995 A merican Institute of Physics.