UHV/CVD growth of Co on Si(0 0 1) using cobalt carbonyl

We report studies of the growth of cobalt from cobalt carbonyl (Co2(CO)8) under ultrahigh vacuum conditions on Si(1 0 0) wafers. Thermal desorption mass spectroscopy and reflection high energy electron diffraction have been used for in situ studies of the growth process. Desorption of CO has been observed with a peak desorption rate at approximately 230 °C. We extract a sticking coefficient of s=1.5×10−3 at 100 °C on the bare cobalt surface. Growth rate measurements at higher temperatures (175–350 °C) are consistent with a higher value for the sticking coefficient. The lower value of the sticking coefficient during growth is attributed to accumulation of decomposition products on the surface. X-ray diffraction studies show that the as-deposited cobalt is fine-grained, and that it reacts to form cobalt disilicide (CoSi2) upon annealing at 800 °C if there is no intervening SiO2.