Bit reading method for silicon nitride read-only memory unit

Abstract

The invention relates to a method for reading the nitride read-only memory cell, which comprises: first, setting the first reading voltage as the word reading voltage of one memory sector; then, when the sector needs erased, erasing the first bit and second bit of said sector and one dual-bit reference memory cell and measuring the first bit to decide the first critical value; then programming the second bit to be logic zero state; measuring the first bit to decide the second critical value; then based on the first and second critical values, adjusting the first reading voltage to be the second reading voltage; then setting the second reading voltage as the word reading voltage of one memory sector, and arranging the word coupled with said sector to read the nitride read-only memory cell inside the sector.

Description

technical field [0001] The present invention relates to a reading method, and in particular to a method for reading bits of a silicon nitride read-only memory cell. Background technique [0002] Flash memory (flash memory) is a non-volatile (non-volatile) semiconductor storage element, which has the characteristics of small size, high capacity, low power consumption and repeatable reading and writing, so it has been widely used in many portable Type 3C products, such as PDA, mobile phone, card reader, mobile disk, adapter card, etc. [0003] The flash memory stores logical data through an array of memory cells, and each memory cell includes a transistor with a gate, a source, and a drain. Wherein, the gate is coupled to a word line. Traditional memory cells use the polysilicon (polysilicon) layer in the gate to store electrons. Since the polysilicon layer is a conductive layer, electrons can move freely in the polysilicon layer, so each traditional memory cell can only sto...

AI Technical Summary

Problems solved by technology

However, it uses complex erase (erase) program (program) and verification program on the reference memory cell, which not only increases the difficulty of circuit design, but also increases the time required for reading

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