Using Q-YIELD: A Case Study
In this case study, we assume that
you are responsible for a semiconductor manufacturing process.
Recently you have been observing serious fluctuations in
the number of device failures.
As a first step, you plot a graph of failures per wafer against
(Click image to enlarge)
There doesn't appear to be any pattern to this data. In
particular, there aren't any obvious correlations with events
such as equipment changes or preventative maintenance. Now
you need to look harder.
From your production database you download all the process
parameters of the batches in question. In this (simplified)
example there are 61 process parameters and 367 process
You consider creating scatter plots of the number of failures
against each of the 61 variables.
But perhaps the relationship is of more than one variable.