Semiconductor memory device, method for driving the same and portable electronic appararus

Abstract

A method for driving a semiconductor memory device includes a memory array having a plurality of memory cells arranged in rows and columns. Each memory cell includes a gate electrode formed on a semiconductor layer via a gate insulating film, a channel region disposed below the gate electrode, a source and a drain as diffusion regions disposed on both sides of the channel region and having a conductive type opposite to that of the channel region, and memory functional units formed on both sides of the gate electrode and having a function of retaining charges. The method includes the steps of: selecting a row line connected to the gate electrode of a memory cell to be selected; grounding a first column line connected to the source of the memory cell to be selected; and applying a first potential to a second column line and a second potential to a third column line at the same time.

Description

technical field [0001] The present invention relates to a semiconductor memory device using a nonvolatile memory, a method of driving the semiconductor memory device, and a portable electronic device. Background technique [0002] In general, flash memory is typically used as nonvolatile memory. [0003] Such as Figure 24 As shown, in the flash memory, a floating gate 902, an insulating film 907, and a word line 903 (control gate) are formed in this order on a semiconductor substrate 901 via a gate insulating film. A source line 904 and a bit line 905 are formed on both sides of the floating gate 902 by diffusion regions, thereby constituting a memory cell. A device isolation region 906 is formed around the memory cell (see, for example, Japanese Unexamined Patent Publication No. Hei 5-304277 (1993)). [0004] The memory cell holds data according to the amount of charge in the floating gate 902 . In a memory cell array constructed by arranging memory cells, rewriting / rea...

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Problems solved by technology

[0006] However, in this flash memory, from a functional point of view, it is necessary to arrange an insulating film 907 for separating the floating gate 902 and the word line 903.

In addition, in order to prevent leakage of charges from the floating gate 902, it is difficult to reduce the thickness of the gate insulating film

Therefore, it is difficult to effectively reduce the thicknesses of the insulating film 907 and the gate insulating film, thereby hindering the reduction in the size of the memory cell.

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