A substrate processing chamber for processing a plurality of wafers in batch mode. In one embodiment the chamber includes a vertically aligned housing having first and second processing areas separated by an internal divider, the first processing area positioned directly over the second processing area; a multi-zone heater operatively coupled to the housing to heat the first and second processing areas independent of each other; a wafer transport adapted to hold a plurality of wafers within the processing chamber and move vertically between the first and second processing areas; a gas distribution system adapted to introduce ozone into the second area and steam into the first processing area; and a gas exhaust system configured to exhaust gases introduced into the first and second processing areas.