Method to detect and classify scratch on semiconductor wafer; involves forming list of faulty cells in co-ordinate system to obtain standard deviation, which is compared with number of faulty cells

摘要

The method involves defining a co-ordinate system for a wafer (1). A list of dropped or faulty cells (4) in the co-ordinate system is created, corresponding to the cell errors on the wafer, and is used with a total number of dropped cells on the wafer, to obtain a standard deviation of faulty cells for a number of different angles. A ratio of standard deviations is compared with the number of faulty cells, to determine the presence of a scratch.