Improvements in or relating to vacuum pumping arrangements

A vacuum pumping arrangement 70 for a semiconductor fabrication assembly comprises a pump 88 having therein an accumulation member (620, figure 6b), a control module 482 configured to divert a deposition flow and a cleaning flow through a swept volume of the pump during a deposition and a cleaning process respectively, wherein the control module monitors at least one of the accumulation and the removal of deposition residue from the accumulation member and alters a characteristic of the deposition or cleaning step or both to control the level of deposition residue remaining. The accumulation member may comprise a residue thickness (626) monitor coupled therewith, and may further comprise a cooling element for selective operation during the deposition step to increase the rate of accumulation of deposition residue and/or a heating element for selective operation during the cleaning step to increase the rate of removal of deposition residue. A method of controlling a vacuum pumping arrangement is also disclosed.