Hydrogen Peroxide → Hydrogen Peroxide

Beteiligte Stoffe

Reaktionsschritte

In this embodiment, the first wet etching is performed using a mixed solution of the composition of H2SO4 :H2O2 =5:1 at an etchant temperature of 140° C. for 20 minutes. The amount of the titanium disilicide film of the C49 structure etched off during the first etching by this mixed solution is extremely less than the amount of the titanium disilicide film of the C49 structure etched off during the first etching by the mixed solution of ammonia water and hydrogen peroxide (under this condition, about 1 nm of the film is etched off) (FIG. 5). During the first etching by the mixed solution of sulfuric acid and hydrogen peroxide, the titanium nitride film formed during the first rapid thermal annealing is removed in about 10 minutes. In this embodiment, therefore, the first wet etching is performed for 20 minutes including margin. Since the first wet etching is performed at 140° C., the maintenance of the composition of the mixed solution is required. During the first wet etching, the titanium-excess titanium silicide (Ti5 Si3) film is only little removed. In this embodiment, therefore, the second wet etching is performed using the mixed solution having a composition of NH4OH:H2O2 :H2O=1:1:5 at room temperature for 30 minutes.

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