Thin cobalt layers have been grown on and in porous silicon by chemica
l vapour infiltration and deposition using HCo(CO)(4). The process can
be controlled to give a capping layer with or without metal in the po
res. Thin coats on the pore walls have been measured to depths of seve
ral mu m and thick coats to depths of 0.1 mu m. Results from mass spec
troscopy indicate that when a cobalt hydride precursor molecule decomp
oses on a pore wall it releases its hydrogen atom accompanied by three
from the pore wall, so forming direct metal-silicon bonds.