Fluorine Atom Production Mechanisms From COF2 and NF3 in Uv Laser Etching of Poly-Silicon and Molybdenum

Ultraviolet laser-induced, radical-etching processes developed by us can provide practical etch rates and selectivities for most of the important film layer combinations used in silicon microelectronic devices. These processes have been demonstrated in simple proximity and projection exposure experiments to produce etch features on surfaces with dimensions of a few tenths of a micrometer.Mechanistic studies suggest that, in our etching processes for polysilicon and molybdenum, fluorine atoms responsible for etching are primarily produced from the precursors COF2 and NF3 on the surface rather than in the gas phase. The predominant production process appears to be photodecomposition of surface adsorbed precursor. Contributions due to precursor pyrolysis or precursor reaction with photogenerated charge carriers are found to be unimportant.