An article in Solid State Technology (1984, Vol. 29, pp. 281–284) described the use of factorial experiments in photolithography, an important step in the process of manufacturing integrated circuits. The variables in this experiment (all at two levels) are prebake temperature (A), prebake time (B), and exposure energy (C), and the response variable is delta line width, the difference between the line on the mask and the printed line on the device. The data are as follows: (1) = –2.30, a = –9.87, b = –18.20, ab = –30.20, c = –23.80, ac = –4.30, bc = –3.80, and abc = –14.70.

(a) Estimate the factor effects.

(b) Use a normal probability plot of the effect estimates to identity factors that may be important.

(c) What model would you recommend for predicting the delta line width response based on the results of this experiment?

(d) Analyze the residuals from this experiment, and comment on model adequacy.