1. A random sample of 50 dies is collected from each lot in a given processes. Calculate the probability that we will find less than three defective dies in this sample if the yield of the process is 98%.
2. An IC manufacturing process is subject to defects that obey a Poisson distribution with a mean of four defects per wafer.
(a) Assuming that a single defect will destroy a wafer, calculate the functional yield of the process.
(b) Suppose that we can add extra redundant dies to account for the defects. If one redundant die is needed to replace exactly one defective die, how many dies are required to ensure a yield of at least 50%?