# Question: An article in Solid State Technology May 1987 describes an

An article in Solid State Technology (May 1987) describes an experiment to determine the effect of flow rate on etch uniformity on a silicon wafer used in integrated-circuit manufacturing. Three flow rates are tested, and the resulting uniformity (in percent) is observed for six test units at each flow rate. The data are shown in Table 4E.7.

a. Does flow rate affect etch uniformity? Answer this question by using an analysis of variance.

b. Construct a boxplot of the etch uniformity data. Use this plot, together with the analysis of variance results, to determine which gas flow rate would be best in terms or etch uniformity (a small percentage is best).

c. Plot the residuals versus predicted flow. Interpret this plot.

d. Does the normality assumption seem reasonable in this problem?

a. Does flow rate affect etch uniformity? Answer this question by using an analysis of variance.

b. Construct a boxplot of the etch uniformity data. Use this plot, together with the analysis of variance results, to determine which gas flow rate would be best in terms or etch uniformity (a small percentage is best).

c. Plot the residuals versus predicted flow. Interpret this plot.

d. Does the normality assumption seem reasonable in this problem?

**View Solution:**## Answer to relevant Questions

An article in the ACI Materials Journal (Vol. 84, 1987, pp. 213-216) describes several experiments investigating the rodding of concrete to remove entrapped air. A 3-in diameter cylinder was used, and the number of times ...Construct and interpret a normal probability plot of the volumes in Exercise 4.1. Consider the control chart shown here. Does the pattern appear random? b. Estimate the process standard deviation. c. What are the limits that you would expect to contain nearly all the process measurements? The viscosity of a polymer is measured hourly. Measurements for the last 20 hours are shown as follows: a. Does viscosity follow a normal distribution? b. Set up a control chart on viscosity and a moving range chart. Does ...Post your question