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'''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.
 
'''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.
  

Revision as of 04:50, 28 January 2019

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Yield
wafer yield.svg
Yield
Yield loss
Concepts

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.

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 scraped
  • Die Yield or wafer sort yield (YD) - fraction of dies that are not scraped
  • 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.