Question

For a given processor, we have the following data: 4. Wafer diameter 100mm Die area 150mm2 Defects per area- 0.03 per cm2 Cost per wafer-$45 Process Complexity factor, N = 10 wafer yield-90% a. How many dies do we have per wafer? b. What is the die yield for our processor? c. What is the cost of each die for this processor?

Answer 1

Part (a)

We have that the total area of a circular wafer

As the diameter of the wafer is 100 mm so, the radius is (100 /2) mm = 50 mm

= $\pi$ r² = 3.14 * 50 *50 mm² = 7850 mm²

Now as the area of one die is given as 150 mm²

so total number of dies that can be cut from this wafer (7850/150) = 52.33 = 52

So total 52 dies are there per wafer.

Part (b)

We know that the die yield for processor

Die yield = Wafer yield * (1+(Defects per area * die area)/N)^(-N)

Substituting all the values we get,

Die yield = (0.9 * (1 + (0.03 * 1.50) / 10)^-10 = 0.9 * (1.0045)^-10 = (0.9 * 0.93) = 0.837

Thus required die yield is 83.70%

Part (c)

The area of each wafer is 7850 mm²

Each wafer costs = $45

Now as the area of one die is given as 150 mm²

So, each die costs = $ (45 * (150 / 7850)) = $ 0.85

Hope this helps.