After pulsing the second purging gas, a zirconium-containing precursor is pulsed into reaction chamber 220, at block 430. In an embodiment, the zirconium-containing precursor is ZTB. In other embodiments, a zirconium-containing precursor includes but is not limited to ZrCl.sub.4 and ZrI.sub.4. The ZTB precursor is pulsed into reaction chamber 220 through the gas-distribution fixture 240 on substrate 210. Mass-flow controller 258 regulates the flow of the ZTB from gas source 253. In an embodiment, the substrate temperature is maintained at about 200.degree. C. The ZTB aggressively reacts at the current surface of substrate 210.