Abnormal silicon oxide growth on cobalt silicide in arsenic-doped N+ active areas

During the deposition process of silicon oxide, we found an unexpected oxide growth on a CoSi 2 layer in an arsenic-doped N+ active area, showing the degradation of contact resistance in this area. The role of arsenic was investigated in order to explain its effects on the abnormal oxidation. This abnormal oxidation was caused by the out-diffusion of silicon atoms from the substrate and was readily influenced by the concentration of arsenic in the silicon substrate and by heat treatment enhancing the out-diffusion of arsenic.