The dependence of the etching property of CoSi2 films in diluted HF solutions on the formation conditions

Three series of CoSi2 thin films which were fabricated by solid state reaction of evaporated Co, Ti/Co and Co/Ti on p-type Si (1 0 0) substrates with different annealing procedures, have been etched in a diluted hydrogen fluoride (0.5 wt.% HF) solution at 30°C. The etching rate ranges from 0.08 to 0.36 nm/s and the induction period (a period in the beginning of the etching process when there is no change in the sheet resistance value) ranges from 48 to 660 s for all those samples. The CoSi2 films formed with a Ti capping layer depends on the annealing parameters more significantly than other two series. The induction period reduces dramatically, but does not eliminate, if a previous step of selective etching in the H2O2–H2SO4 solution and (or) the NH3–H2O2–H2O solution is performed. The surface roughness of the etched samples is monitored by atomic force microscopy (AFM) measurements.