A method for reading data from flash memory of split-gate type double-bit storage unit

Abstract

The invention provides a data reading method of a split gate type double-bit memory cell flash memory. A traditional manner of taking a current of a reference cell under a state of ''11'' as a read judgment standard is changed into a pattern of taking a current of the reference cell under a state of ''10'' multiplied by a fixed proportion as the read judgment standard, so that the sensing margin can be guaranteed and the reliability of data reading of the split gate type double-bit memory cell flash memory can be improved; yield loss caused by programming performance differences between differentlots can be avoided by means of calculating a current average value of a plurality of reference cells; further, after the split gate type double-bit memory cell flash memory is erased by block every time and before a new round of data reading is carried out, each reference cell is re-programmed, and each reference cell is reset to be the state of ''10'', so that the condition that the current value of the reference cell under the state of ''10'' is affected and changed due to the programming strongaftererasure by block can be avoided, and the reliability of data reading of the split gate type double-bit memory cell flash memory can be further improved.

Description

technical field [0001] The invention relates to the technical field of FLASH memory testing, in particular to a method for reading data from a split-gate double-bit storage unit flash memory. Background technique [0002] Flash memory (ie, FLASH memory) is a non-volatile solid-state storage device that can electrically erase or write data. Compared with other memories, the advantages of flash memory include low power, non-volatile storage, high performance, physical stability, portability, etc. Flash memory is widely used in electronic devices, especially portable electronic devices such as digital cameras, personal digital assistants (PDAs), Moving Picture Experts Group-1 (MPEG-1) or Moving Picture Experts Group-2 (MPEG-2) Audio Level III (referred to as MP3) players, mobile phones, tablet computers, etc. These electronic devices can use various interface protocols, such as Secure Digital (SD), Micro Secure Digital (μSD), Embedded Secure Digital (eSD), Embedded Multimedia...

AI Technical Summary

Problems solved by technology

However, in actual situations, due to the existence of process parameter deviations, the actual values ​​of the high and low current or voltage signals generated by the data unit and the reference current Iref or reference voltage Vref signal of the reference unit may deviate from the target design value, resulting in reading Decision Margin Reduction

When the read decision margin cannot overcome the input mismatch of the read circuit itself, read errors may occur, affecting the data read reliability of the memory

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