One embodiment thermal chemical vapor deposition method includes exposing a substrate within a chamber to first and second deposition precursors effective to thermally chemical vapor deposit a material on the substrate, and exhausting unreacted first and second deposition precursors from the chamber through a vacuum pump via a first exhaust line comprising a filter. A reactive gas is flowed to the material on the substrate, with the reactive gas being reactive with the material. After flowing the reactive gas, an inert purge gas is flowed through the chamber and through the vacuum pump. The flowing of the inert purge gas to the vacuum pump is through a second exhaust line not comprising the filter. The exposing, the flowing of the reactive gas, and the flowing of the inert purge gas are repeated effective to deposit material of desired thickness on the substrate.