A system and/or method for heat treatment of substrates. The system includes a housing that defines a heating chamber and a door assembly that encloses an opening of the heating chamber. The door assembly may be opened and closed. When opened, the door assembly defines a loading slot for loading substrates into and unloading substrates from the heating chamber. The door assembly is coupled to a first actuator and a control unit is coupled to the actuator to move the door assembly between a plurality of loading positions. The system may also include a loading assembly mounted to the door assembly to facilitate insertion and removal of substrates from the heating chamber.