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wafer yield.svg
Yield loss

Yield is a quantitative measure of the quality of a semiconductor process. It is the fraction of dies on the yielding wafers that are not discarded during the manufacturing process.


Although the goal of every fabrication process is to produce only working dies, in practice the process is never perfect and not all dies work or operate as desired within specs. Yield is a quantitative measurement of the process quality in terms of working dies.

Equation upper Y equals StartFraction upper N Subscript good Baseline Over upper N Subscript total Baseline EndFraction


  • Ngood - number of working dies per wafer
  • Ntotal - number of dies per wafer

For example, consider a process with a D0 = 0.5/cm², for dies the size of 360 mm².

360mm2 wafer yield 0.05pcm2.svg

There are 150 dies per wafer and around 24 defective dies per wafer, therefore the yield is Equation StartFraction 126 Over 150 EndFraction equals 84 percent-sign .

Measuring yield

The final die yield is the compounded yield of all the independent steps that are required to produce a functional die. Those include:

  • Wafer Yield (YW) - fraction of wafers that are not scrapped
  • Die Yield or wafer sort yield (YD) - fraction of dies that are not scrapped
  • Assembly Yield (YA) - fraction of chips that are not scrapped during the packaging stage
  • Burn-in Yield (YB) - fraction of chips that pass burn-in

The overall yield is therefore Y = YW ⋅ YD ⋅ YA ⋅ YB

Yield loss

Yield loss refers to the source that affects the final yield. Those usually fall into two categories:

During a new process technology bring-up, yield loss can be very high (< 40% yield). The process of identifying yield losses, quantifying them, and improving them is referred to as yield learning.

Yield modeling

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Design for Manufacturability

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See also