Abstract: Methods for depositing silicon oxide in a batch reactor are provided. In some embodiments, a plurality of vertically separated substrates is provided in a reaction chamber. Tetraethyl orthosilicate (TEOS) is pulsed into the reaction chamber by direct liquid injection. Ozone is flowed into the reaction chamber simultaneously or alternately with the TEOS. The deposition is performed at about 10 Torr or less to extend the mean free path length of the ozone molecules. According to some embodiments, the deposition allows openings in the substrates to be filled while the occurrence of voids is maintained at a low level.