Maximizing Output during Ramp by Integrating Capacity and Velocity

In the semi-conductor industry, factories ramp their production capacity in parallel with tool (machine) installations. Ramp capacity, and subsequently wafer starts, are aligned with additional installs of the most expensive tool. Subsequently, starts are set to the full capacity of that limiting toolset. In this paper, we argue that this may not be best method to maximize output over the ramp period and that by keeping ramp starts below constraint capacity, increased levels of cumulative output can be achieved for a desired planning horizon (e.g., the first year of production). A mathematical framework of the problem is provided to support our hypothesis, together with numerical examples and a set of simulation experiments.