Die yield: definition · Chip Field Guide

Beginner

The share of chips on a wafer that come out working.

Novice

The fraction of chips on a wafer with no fatal defect. It falls as chip area grows, because a bigger chip is more likely to catch one. The simplest model is $Y = e^{-D_0 A}$ , where $D_0$ is defects per cm² and $A$ is the chip’s area.

Expert

Modeled with Poisson, Murphy, Seeds or negative binomial statistics, which differ in how they treat defects that bunch together. Bunching leaves more chips clean than random scattering would, so the Poisson model is pessimistic for large chips; the negative binomial’s cluster parameter $\alpha$ sets how strongly defects bunch.