1) Find the final yield for a nine-mask-level process in which the average fatal defect density per cm2 is 0.1 for four levels, 0.25 for four levels, and 1.0 for one level. The chip area is 50 mm2. Use Y = e-NDA (Note: N = #of levels, D=average number of defects/unit area, A=area of chip)
2) An optical lithographic system has an exposure power of 0.3 mW/cm2. The required exposure energy for a positive photoresist is 140 mJ/cm2 and for a negative photoresist is 9 mJ/cm2. Assuming negligible times for loading and unloading wafers, compare the wafer throughput for positive photoresist and negative photoresist.