An article in the IEEE Transactions on Electron Devices (Nov. 1986, pp. 1754) describes a study on polysilicon doping. The experiment shown below is a variation of their study. The response variable is base current.

Anneal Temperature (∘ Polysilicon C)

Doping (ions) 900 950 1000 1 × 1020 4.60 10.15 11.01 4.40 10.20 10.58 2 × 1020 3.20 9.38 10.81 3.50 10.02 10.60

(a) Is there evidence (with ???? = 0.05) indicating that either polysilicon doping level or anneal temperature affects base current?

(b) Prepare graphical displays to assist in interpreting this experiment.

(c) Analyze the residuals and comment on model adequacy.

(d) Is the model y = ????0 + ????1x1 + ????2x2

+ ????22x2 2 + ????12x1x2 + ????

supported by this experiment (x1 = doping level, x2 =

temperature)? Estimate the parameters in this model and plot the response surface.