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On-Line Monitoring When the Process Yields a Linear Profile

2000; Taylor & Francis; Volume: 32; Issue: 4 Linguagem: Inglês

10.1080/00224065.2000.11980027

2575-6230

Lan Kang, Susan L. Albin,

Advanced Statistical Methods and Models

Control charts monitor processes where performance is measured by one or multiple quality characteristics. Some processes, however, are characterized by a profile or a function. Here we focus on monitoring a process in semiconductor manufacturing that is characterized by a linear function. While the linear function is the simplest, it occurs frequently, for example in calibration studies. Two monitoring approaches are proposed: (1) monitor parameters, slope and intercept, with multivariate T2 and (2) monitor average residuals between sample and reference lines with EWMA and R charts. Simulation studies indicate that both methods work well. Both methods are extendable to complex functions.