Editing yield

{{title|Yield}}{{yield}}
'''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.

== Overview == 
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.

:<math>Y = \frac{N_\text{good}}{N_\text{total}}</math>

Where,

* N<sub>good</sub> - number of working dies per wafer
* N<sub>total</sub> - number of dies per wafer

For example, consider a process with a [[defect density|D<sub>0</sub>]] = 0.5/cm², for [[dies]] the size of 360 mm².

: [[File:360mm2 wafer yield 0.05pcm2.svg|500px]]

There are 150 dies per wafer and around 24 defective dies per wafer, therefore the yield is <math>\frac{126}{150} = 84%</math>.

=== 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]] (Y<sub>W</sub>) - fraction of wafers that are not scraped
* [[Die Yield]] or wafer sort yield (Y<sub>D</sub>) - fraction of dies that are not scraped
* [[Assembly Yield]] (Y<sub>A</sub>) - fraction of chips that are not scrapped during the packaging stage
* [[Burn-in Yield]] (Y<sub>B</sub>) - fraction of chips that pass [[burn-in]]

The overall yield is therefore Y = Y<sub>W</sub> ⋅ Y<sub>D</sub> ⋅ Y<sub>A</sub> ⋅ Y<sub>B</sub>

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

* [[Parametric Yield Loss]] - Dies that function but not within the desired specifications
* [[Catastrophic Yield Loss]] - Dies that do not function due to a defect

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 ==
* [[Chiplet]]