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#4. Three different plasma etch processes (a, b, and c) each involve ion enhanced etching but have very different characteristics. The etch rate versus ion flux behavior in each is shown below. For each process, sketch what the etch profile would look like if you are using that process to etch the material with a mask, as shown below on the top left (assume zero etch rate for the mask). Explain. (12 points - 4 for each part). Etch RateIon flux00(a)Etch RateIon flux00(b)Etch RateIon flux00(c)Mask
9 #5. In the CMOS process we described in class, it is the case that when the gate oxide is regrown just before the poly gate deposition (page 7 in the class notes), some annealing of the implant damage will occur. The damage present when the gate oxide is regrown, is due to the VTHimplants (page 6). Suppose the B+implant is 2x1012cm−2@50KeV. Further suppose that the gate oxidation is at 800 ˚C for 10 minutes. Approximately what fraction of the implant damage is actually repaired during the gate oxide growth? (10 points).