An article in Solid State Technology, “Orthogonal Design for Process Optimization and Its Application to Plasma Etching” by G. Z. Yin and D. W. Jillie (May 1987) describes an experiment to determine the effect of the C2F6 flow rate on the uniformity of the etch on a silicon wafer used in integrated circuit manufacturing. All of the runs were made in random order. Data for two flow rates are as follows:

C Uniformity Observation 2F6 Flow

(SCCM) 1 2 3 4 5 6 125 2.7 4.6 2.6 3.0 3.2 3.8 200 4.6 3.4 2.9 3.5 4.1 5.1

(a) Does the C2F6 flow rate affect average etch uniformity?

Use ???? = 0.05.

(b) What is the P-value for the test in part (a)?

(c) Does the C2F6 flow rate affect the wafer-to-wafer variability in etch uniformity? Use ???? = 0.05.

(d) Draw box plots to assist in the interpretation of the data from this experiment.