Yield
The manufacturer of integrated circuited is ultimately interested in how many finished chips will be available for sale. Wafer yield is related to the complexity of the process and is strongly dependent on the area of the integrated-circuit die.

Uniform defect densities

A classical problem in probability theory in which n defects are randomly placed in N die sites. The probability P_k

k - exactly # of defects
n - # of defects per wafer
N- # of die sites

for large n and N

where l = n/N

The yield is given by the probability that a die is found with no defects

Y = P_o = e ^-l

A - area of single die

wafer area = NA

D_o - density of defects

l = n/N = D_oA

Y = e ^-DoA

Nonuniform Defect Densities

f(D) probability density for D

The final yield depends on the form of f(D). Here are just three examples: