An in situ method for forming a HfO2 high-k dielectric layer in a batch wafer processing system. The method comprises first loading a plurality of wafers into a process chamber, and then pre-treating the plurality of wafers in the process chamber with a first oxidizer. After pre-treating the wafers, and without removing the wafers from the process chamber, the method then comprises depositing HfO2 on the plurality of wafers by atomic layer deposition, which comprises a plurality of deposition cycles, each cycle comprising alternating exposure of the plurality of wafers in the process chamber to a second oxidizer and a hafnium precursor. The hafnium precursor is selected from hafnium tert-butoxide (HTB) or hafnium tetra-diethylamide (TDEAH).