Nonvolatile memory control device and nonvolatile memory control method

Abstract

Disclosed are a nonvolatile memory control device and a nonvolatile memory control method. The nonvolatile memory control device performs data reading / writing control on partitions of a rewritable nonvolatile semiconductor memory. The device includes an erase cycle counting unit, a read cycle counting unit, a data reading / writing unit and a control unit. The erase cycle counting unit counts the number of erase cycles in total per partition. The read cycle counting unit counts the number of continuous read cycles that same data is read per partition. The data reading / writing unit performs data reading / writing of data on a nonvolatile memory. On the conditions that the number of erase cycles of a specific partion is equal to or larger than a predetermined number of erase cycles and a partition having the greater number of erase cycles than that of the specific partition and the larger number of read cycles than that of the specific partition exsits, the control unit controls the data reading / writing unit to exchange data in the first partition and data in the second partition.

Description

technical field [0001] The present invention relates to a nonvolatile memory control device and a nonvolatile memory control method. Background technique [0002] In the past, rewritable semiconductor nonvolatile memory such as NAND flash memory (abbreviated as nonvolatile memory), writes data by injecting electrons into the floating gate through a tunnel oxide film, and writes data by pulling out electrons. Data Erasure. In addition, reading and writing of data is performed in units of pages consisting of a plurality of cells, and when erasing data is further performed in units of blocks consisting of a plurality of pages. [0003] However, when data in one cell is rewritten, the tunnel oxide film is degraded by electrons passing through the tunnel oxide film, and the lifetime of the cell is exhausted. Therefore, there is a limit to the number of erasing times for each block. In addition, generally, it is often used in units of partitions composed of a plurality of blocks...

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Problems solved by technology

[0007] Therefore, there is a problem that such rewriting of the data itself also occurs in the equalization in the nonvolatile memory device that focuses only on the number of times of rewriting (the number of times of erasing) of the partition as described in Patent Document 1. When the data with many times (erasing times) is stored again in the partition with the most rewriting times (erasing times), there is a possibility that the life of the non-volatile memory will be shortened.

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