Andrew Beckett
Senior Fellow
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Life, don't talk to me about Life...
Posts: 1742
Bracknell, UK
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That's a fairly reasonable first order approximation. Of course, most of the time the actual die placement on the mask (and the corresponding stepper information for when the reticles are stepped) will be optimised to maximise the number of dies. That equation obviously doesn't take into account the wafer flat, or the ring around the edge which can't be used (in some cases), nor if you have test dies on the wafer, and of course the die size needs to include the scribe - you don't necessarily know how big the scribe is up front because it will depend on how many test structures need to be put in the scribe, but normally it is kept to be as small as possible to maximise the utilised area of the wafer.
Regards,
Andrew.
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