Semiconductor storage device, method for controlling the same and control program

摘要

According to one embodiment, a semiconductor memory stores a program for causing a memory controller to operate in at least one of first and second modes. In the first mode, for each of the blocks, the memory controller autonomously erases and writes data and reads the written data, and determines that the block or the semiconductor storage device is defective when a count of errors in the read data exceeds a correction capability or a threshold. In the second mode, when error correction of read substantial data fails, the memory controller reads the substantial data which failed in the error correction using a read level shifted from the present read level.

主权项

1. A semiconductor storage device comprising:
a semiconductor memory comprising blocks, the blocks including memory cells; and a memory controller, wherein the semiconductor memory stores a firmware for causing the memory controller to operate in at least one of a first mode and a second mode; and the memory controller
writes substantial data and redundant data in the semiconductor memory,reads substantial data and corresponding redundant data from the semiconductor memory, and corrects an error, if any, in the read substantial data based on the read redundant data,reads the firmware when power is supplied, and enters the first or second mode in accordance with the firmware when the firmware is executed by the memory controller,in the first mode, for each of the blocks, erases data, writes data, and reads the written data, corrects errors of the read data, and determines that the block or the semiconductor storage device is defective when the read data is uncorrectable, andin the second mode, reads substantial data from the semiconductor memory using a first read level, corrects an error in the read substantial data when the error in the read substantial data is detected, reads the substantial data using a second read level when the error correction of the read substantial data fails, the second read level being shifted from the first read level.