An experiment was run in a semiconductor fabrication plant in an effort to increase yield. Five factors, each at two levels, were studied. The factors were A= aperture setting (small, large), B= exposure time (20% below nominal, 20% above nominal), C= development time (30 and40 s), D= mask dimension (small, large), and E= etch rate (14.5 and 15.5 min). The unreplicated design was used with the results in standard order.

(1) = 7 d= 8 e= 8 de= 6
a= 9 ad= 10 ae= 12 ade= 10
b= 34 bd= 32 be= 35 bde= 30
ab= 55 abd= 50 abe= 52 abde= 53
c= 16 cd= 18 ce= 15 cde= 15
ac= 20 acd= 21 ace= 22 acde= 20
bc= 40 bcd= 44 bce= 45 bcde= 41
abc= 60 abcd= 61 abce= 65 abcde= 63

(a) Construct a normal probability plot of the effect estimates. Which effects appear to be large?
(b) Conduct an analysis of variance to confirm your findings for part (a) Hint: Conduct analysis of variance with the large effects found in (a), and draw conclusion.
(c) Write down the fitted regression model relating yield to the significant process variables found in (b).
(d) Plot the residuals on normal probability paper. Is the plot satisfactory?
(e) Plot the residuals versus each of the five factors. Comment on the plots.
(f) Interpret any significant interaction. Hint: Construct an interaction plot.
(g) What are your recommendations regarding process operating conditions?