Dual wafer load lock

A method and apparatus for transferring a substrate between a first environment having a first pressure and a second environment having a vacuum pressure is provided. In one embodiment, the apparatus comprises a chamber body having a first port disposed in a first wall and a second port disposed in a second wall that seals the chamber from the first and second environments. A cooling plate, a first substrate holder and a second substrate holder are disposed within the chamber body. The cooling plate is disposed at the bottom of the chamber body. The first port and the second port are sequentially opened and the pressure within the load lock regulated to allow substrate to pass through the load lock. A window is disposed in the top of the chamber body that allows a metrology device to view the chamber volume.