The present disclosure generally relates to methods and apparatus for heating a substrate as well as a slot management method for a thermal treatment chamber that in one embodiment includes providing a first substrate to a first slot of a carrier in the thermal treatment chamber via a transfer opening formed in the thermal treatment chamber, the first substrate having a specified anneal time, heating the substrate, moving the carrier to a lowermost position in the thermal treatment chamber using an elevator mechanism coupled to the carrier, and moving the carrier such that the first slot is in a position adjacent to the transfer opening using the elevator mechanism within a carrier transfer time period and transferring the first substrate out of the thermal treatment chamber at a determined time period for anneal.