Deep level transient spectroscopy study of the damage induced in n-type silicon by a gate oxide etching in a CHF3/Ar plasma

Deep level transient spectroscopy was used to detect the presence of deep levels correlated to the defects induced in the Si substrate by a CHF3/Ar dry etch of a 550 A gate oxide as a function of the rf power. Several energy levels were observed; some of them were due to the processing before the dry etching. Three traps produced by the dry etching, with Arrhenius plot activation energies, respectively, Ena1=350 meV, Ena2=220 meV, and Ena3=100 meV, and capture cross sections around 10−20 cm2 were detected. The correlation with the surface recombination velocity variations and the F and C diffusion in the Si substrate was investigated.