Analysis Of Error Characteristics Based On NAND Flash

NAND Flash is a non-volatile memory that has been widely used in various storage applications.Multi-level memory cells(MLC)have the advantage of low price and large capacity compared to single-level memory cells(SLC).From the physical structure characteristics of NAND Flash,bit flip is inevitable;and MLC has higher storage density than SLC,so the threshold voltage difference between the logic states of MLC is smaller than that of SLC,which makes MLC NAND Flash more prone to bit flip than SLC NAND Flash.How to ensure the integrity and reliability of data has become an important research topic.This thesis focuses on the research and analysis of the influence of the external environment and flash memory characteristics on the NAND Flash bit error rate and bit flip feature,and reflects the current life and reliability state of NAND Flash through the bit error rate.The work of this paper is mainly composed of four parts:The first part is introduced by the micro level and elaborated at the macro level firstly.The micro level mainly involves the structure principle of the storage cell.The difference between the number of bits saved by the Flash basic cell is introduced.The three commonly used Flash types are introduced respectively.The macro level content is expanded from the basic cell to the cell.Flash overall chip architecture,and based on this,the basic operation of NAND Flash is introduced in detail.The second part summarizes the error characteristics of the main research objects in this paper.The types of errors are mainly divided into four types:erase error,data resident error,read interference error and programming error.The environmental factors are mainly used to study the effect of temperature on its bit flipping.Starting with the characteristic factors,the overall impact of the four errors is studied.The third part involves the construction of the experimental environment and the preparation of the test firmware,and the research-oriented experimental test plan is based on the cause of the error.In the fourth part,based on the previous research on the error characteristics,the specific test experiments are carried out,and the relevant experimental results are obtained.The influence of these environmental factors and characteristic factors on the NAND Flash bit error rate and bit flip is analyzed,and the relevant conclusions are summarized.The research on Flash characteristics is mainly considered from the practical aspects.Since the generation of errors in the use of Flash chips are inevitable,the method of correcting these errors is the top priority of the research.There are many error correction methods in the application field.The error correction by hardware is very large for the resources that are not rich enough.How to reduce or avoid the mistakes through other levels is the main purpose of this paper.The error analysis results obtained in this paper are of great significance for the subsequent coding error correction research.