Flash Memory Testing

This chapter is not aimed at providing a complete testing theory about Flash; its objective is to present and analyze the most critical aspects related to Flash testing, the tools and methods to improve their testability; to give an idea of the test flow, and of its relation with the excellent quality and reliability that Flash have reached. Aspects related to test cost and productivity are also presented.The subject is seen from the viewpoint of the Flash manufacturer and treated in very practical terms, with the intent to give an insight into these aspects to the non-expert reader.Although most of the aspects may be valid for other Flash technologies, this chapter refers to the mainstream Flash technology: NOR architecture, erased by Fowler-Nordheim, programmed by Channel Hot Electrons.The subjects of testing Known-Good-Die, Flash Cards or embedded Flash are not presented: each one would have required a dedicated chapter.For the reader interested in a more theoretical and formal insight into Semiconductor Memory testing, excellent books exist (e.g. [1]); for the test engineer with the need to go more deeply in the practical details of Flash testing, exhaustive datasheets and application notes are published by Flash manufacturers.