Patent ID: 8857465

Claim:
A method for realizing a vacuum in at least one vacuum chamber, wherein the method comprises: providing an arrangement comprising a plurality of vacuum chambers, wherein each vacuum chamber is connected to a shared vacuum system comprising: a plurality of turbo molecular pumps, each turbo molecular pump being separately connected to a corresponding vacuum chamber; at least one common fore pump, and a piping system comprising one or more common pipes for connecting the at least one common fore pump to each of the plurality of turbo molecular pumps, the piping system further comprising flow regulators for controlling a flow within the piping system; selecting at least one vacuum chamber for pump-down; and separately pumping down the at least one selected vacuum chamber by means of the shared vacuum system, comprising: activating, in a first pumping stage, the at least one common fore pump for jointly pumping down selected vacuum chambers to a pressure with a first pressure value, and activating, in a second pumping stage, a turbo molecular pump of the at least one selected vacuum chamber for separately pumping down the selected vacuum chambers to a pressure with a second pressure value, the second pressure value being lower than the first pressure value; wherein the method further comprises: de-activating the at least one common fore pump at a predetermined time after activating the turbo molecular pump.