;In this paper, we use Boomerang Chart that we published in the past to analyze the classified wafer maps in a great view, whether the distribution of defects uniform or not and verify it in mass production. At first, we choose several kinds of size of wafers that we would like to analyze, and simulate basic curve according to these several kinds of size. In this experiment, we will create parameters NBD and NCD from every wafer in every data, and normalize the two parameters to create two new parameters, NNBD and NNCD. We will get the standard deviation according to the two parameters and compare with basic standard deviation to observe every failure type’s on the change in value, we will judge whether a wafer uniform or not and the situation of clustering of bad dice by this. Then, we will view whether there are systematic errors in non-classified data based on the result.
In this experiment, we use the relationship between standard deviation and normal distribution , To identify whether the system is a systematic error type by observing the feature value , and find out the position and the situation of clustering of every failure type by observing Z-Score. Finally confirm the practicability of Z-Score through non-classified data set to get the achievement of increasing yield、testing efficiency and reduce the production cost.
