Solve Only By Using Minitab 1 (105.66 KiB) Viewed 28 times
Solve Only By Using Minitab 2 (66.23 KiB) Viewed 28 times
Solve Only By Using Minitab 3 (100.27 KiB) Viewed 28 times
6.65. (a) Thirty observations on the oxide thickness of individual silicon wafers are shown in table 68.23. Use these data to set up a control chart on oxide thickness and a moving range chart. Does the process exhibit statistical control? Does oxide thickness follow a normal distribution? TABLE 6E.23 Data for Exercise 6.65 Oxide Oxide Wafer Thickness Wafer Thickness 1 45.4 16 58.4 51.0 3 41.2 47.1 2 18.6 49.5 44.0 509 55.2 45.5 52.8 453 4 5 6 7 8 9 10 11 12 13 14 15 17 18 19 20 21 22 23 24 25 26 27 28 29 30 46,3 45.7 60.6 510 53.0 56.0 47.2 18.0 55.9 50.0 47.9 53.4 ง 53.9 49.8 46.9 49.8 45.1 ū
(b) Following the establishment of the control charts in part (a), 10 new wafers were observed. The oxide thickness measurements are as follows: Wafer Wafer 1 2 3 4 Oxide Thickness 543 57.5 64.8 62.1 59.6 6 7 8 9 10 Oxide Thickness 51.5 58.4 67.5 61.1 63.3 Plot these observations against the control limits determined in part (a). Is the process in control?
(c) Suppose the assignable cause responsible for the out-of-control signal in part (b) is discovered and removed from the process. Twenty additional wafers are subsequently sampled. Plot the oxide thickness against the part (a) control limits. What conclusions can you draw? The new data are shown in Table 68.25. TABLE 6E.25 Additional Data for Exercise 6.65, part (0) Oxide Oxide Wafer Thickness Wafer Thickness 43.4 46.7 44.8 1 2 3 4 5 6 7 & 9 10 51.3 49.2 46.5 48.4 50.1 53.7 45.6 11 12 13 14 15 16 17 18 19 20 50.0 61.2 46.9 44.9 46.2 53.3 44.1 474 513 42.5
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