Uniformity measures in semiconductor manufacturing

One of the critical specifications for a manufactured artifact is that of ´uniformity´, a measure of consistency. Numerous different ways of measuring and reporting uniformity has led to some confusion in discussion. This has a real bearing when trying to compare machine performances, or when relating performance to specifications. This paper describes various ways of reporting the ´uniformity´ of an object-for example, the flatness of a semiconductor wafer. The paper also prescribes a way of deciding on the appropriate measure, using a decision flowchart.