Nonvolatile semiconductor memory with dual latch sense amplifier

摘要

A memory includes first and second select gate transistors, memory cells, a source line, a bit line, a selected word line which is connected to a selected memory cell as a target of a verify reading, a non-selected word line which is connected to a non-selected memory cell except the selected memory cell, a potential generating circuit for generating a selected read potential which is supplied to the selected word line, and generating a non-selected read potential larger than the selected read potential, which is supplied to the non-selected word line, and a control circuit which classifies a threshold voltage of the selected memory cell to one of three groups by verifying which area among three area which are isolated by two values does a cell current of the selected memory cell belong, when the selected read potential is a first value.

主权项

1. A nonvolatile semiconductor memory comprising:
a first transistor; a second transistor; a memory cell unit including memory cells coupled in series; word lines coupled to gates of the memory cells; a sense amplifier including a first node, a third transistor, a fourth transistor and a first capacitor, a first terminal of the third transistor being coupled to the first node, a first terminal of the fourth transistor being coupled to both the first node and the first terminal of the third transistor, and a first terminal of the first capacitor being coupled to the first node; and a controller configured to perform a verify operation including a first operation and a second operation, to apply a first voltage to a gate of the fourth transistor and apply a second voltage to a gate of the third transistor in the first operation, to apply a third voltage to the gate of the fourth transistor and apply a fourth voltage to the gate of the third transistor in the second operation, and to perform the first operation and the second operation during applying a verify voltage to a first word line selected from the word lines, the second voltage being higher than the first voltage and the fourth voltage being higher than the third voltage.