NO-lnduced fast chemical dry thinning of Si wafer in NF ₃ remote plasmas

In this work, a fast chemical dry thinning process of a Si wafer was investigated in NF ₃ remote plasmas with direct injection of NO gas into the reactor. Direct injection of NO gas during the supply of F radicals from NF ₃ remote plasmas was very effective in increasing the thinning rate. The NO-induced surface reactions on a roughened Si surface promote chemical reaction of the fluorine atoms with the silicon and as a result, the effective removal of silicon atoms from the silicon wafer via SiF ₄ formation significantly enhances the chemical dry thinning rate. A Si wafer thinning rate as high as 24.4 μm/min was obtained at room temperature. The process regime for enhancement of the silicon wafer thinning rate was extended at elevated temperatures.