4.6.3 Load locks and noncorrosive gases
The ACP 120 is an entry-level model of water cooled multi-stage Roots pumps. Pumps in the ACP series are not suitable for pumping down large quantities of corrosive gases. However, ACP series pumps can be used to handle at least traces of corrosive gases. In this case, inert gas purge is used in which the bearings are protected with an inert gas curtain and process gases are diluted by introducing inert gas into the pump stages.
The ACP 120 can either be operated as a stand-alone pump or in combination with a Roots pump as an ACG 600 pumping station that is an ideal solution for industrial use and which benefits from the design of corrosive gas versions for the semiconductor industry. ACP/ACG pumps are ideally suited for clean processes through their friction-free design. They achieve excellent long-term stability and long maintenance intervals.
Figure 4.12: ACP 120
Lock pumps for the semiconductor industry have an ”L“ for ”load lock“ in their designation. In contrast to the ACP 120 described above, they are equipped with a housing and a controller. A frequency converter ensures globally reproducible performance parameters irrespective of the mains voltage and frequency.
L-series pumps are fitted with an operating hour counter, status lights and a and can be operated in a local and remote control mode between local and remote control mode.
Inlet and outlet flanges are fitted to the rear of the pump as well as an input-output interface which allows it to be linked to the control unit of a semiconductor production machine. A serial interface is optionally available to enable the pump, for example, to be connected to a monitoring network. Connections for water cooling and an optional energy-saving option are also located on the rear of the pumps (see Figure 4.13).
The optional energy-saving option (Energy Saving, ES) integrated in the pump housing reduces the pump power consumption by up to 50 %. The cost of ownership for the operator is significantly reduced as a result. Besides saving energy, the A 100 L ES can attain an ultimate pressure of 7 · 10-4 hPa. The noise level is also reduced by 3 dB(A).
Figure 4.13: A 100 L rear side with connections
By keeping the pump surfaces free, the units can also be stacked and therefore minimize the space taken in the cleanroom of a semiconductor fab or in a the basement. Thanks to its combination of a minimal footprint, stackability, high pumping speed even at atmospheric pressure, energy-saving option, low ultimate pressure and high reliability and long-term stability, the L series is the ideal solution for all load-lock processes.
The low final pressure and the reduced noise level make them attractive for analytical and research and development applications.
