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Equation 4 · Part 3 · Advanced Semiconductor Fabrication in Practice: An Advanced Technical Guide

=

Y=e−AcD0Y = e^{-A_c D_0}
=

What this part means

The expressions on both sides represent the same quantity under the stated assumptions.

Its job in the formula

The equals sign connects the complete expression on the left with the complete expression on the right. Both sides must have compatible units.

The passage around this formula

A finished, fully-processed 300-millimeter wafer at an advanced node carries somewhere in the neighborhood of several hundred to a few thousand individual dies, and not all of them will work. The simplest model process engineers reach for treats random defects as a Poisson process across the wafer: given an average defect density D0D_0 (critical defects per unit area) and a die’s critical area AcA_c (the area within which a defect is actually fatal to that die’s function), the expected fraction of working die is Y=e−AcD0Y = e^{-A_c D_0}. This Poisson form is known to be pessimistic in practice, because real defects cluster rather than distributing independently across the wafer — a…

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Learn the underlying idea

An equals sign says that the expression on its left and the expression on its right have the same value under the stated definitions and assumptions.

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Sources cited in the article section

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