Optimal maintenance headcount allocation: an application of Chebyshev Goal Programming

In a semiconductor wafer fabrication facility (as well as virtually any type of factory), the allocation of maintenance technicians to tool sets (or clusters of tools) plays a crucial role in the determination of tool set availability. Tool availability, in turn, determines factory capacity and serves to drive factory performance in terms of outs, inventory, cycle time and WIP velocity. With tools now composing 70% or more of the cost of current (i.e. 300 mm wafer) multi-billion dollar facilities, even seemingly slight increases in tool set availability can translate into savings on the order of millons or hundreds of millions of dollars. In this paper, an approach for deriving the allocation of maintenance technicians for this problem by means of Chebyshev Goal Programming is described and illustrated.