Atmospheric pressure chemical vapor deposited aluminum oxide films based on trimethyl-aluminum and oxygen as precursors reaching a surface passivation quality comparable to atomic layer deposited aluminum oxide layers are presented. Demonstrated are charge carrier lifetime values up to 8 ms on n-type Cz-Si for fired AlOx/SiNx:H passivation stacks, common to PERC and PERT solar cell designs. The APCVD AlOx layers are highly temperature stable for set peak firing temperatures in the range of 700-920°C allowing for surface recombination velocities < 2 cms- 1. The influence of temperature during AlOx deposition in the APCVD tool is investigated concerning Si material and fundamental passivation effect properties. The latter are investigated in comparison to ALD AlOx determining the underlying causes for higher lifetime after firing for APCVD AlOx films.