What does the fabrication yield mean ?

[zahrein]

Fabrication yield?

It is mentioned in the book,

"By making the 1C chips as small as possible, the processing cost per chips decreases and fabrication yield increases, both contributing to lower cost."


I cant understand the meaning of fabrication yield?
Can anyone explain or give me some links that i can understand the key word above.

 

[yoho]

Re: Fabrication yield?

fab yield = number of good dies / total number of dies = number of good dies /(number of good dies + number of bad dies)

 

[rajesh13]

Re: Fabrication yield?

It is mentioned in the book,

"By making the 1C chips as small as possible, the processing cost per chips decreases and fabrication yield increases, both contributing to lower cost."


I cant understand the meaning of fabrication yield?
Can anyone explain or give me some links that i can understand the key word above.

This simply means that if you shrink your design, then on the same wafer you can fabricate more no. of chips. That simply ammounts to more no. of chips at the same processing cost. But in reality it is not that straight forward. Because with the shrinkage, more & more complex things will come into picture, & things will not be that easy.

 

[Colbhaidh]

Re: Fabrication yield?

It is also related to what the Fabs call defect density. Every fab will have an intrinsic defect density where random defects cause devices to fail. This is measured in defects per square cm. So if you have a fixed defect density, the smaller the device size the less chance it has of being killed by random defects.
However, new technologies (shrinks) often have lower yields because they are not mature and may still have systematic defects. So it is not always true that making the devices smaller = better yield.
Also when you go too small, the devices begin to think they are toasters !