Matsushita Electric Industrial Co., Ltd.

Matsushita Electronics Corporation

Masafumi Doi

Keita Takahashi

Hiroyuki Doi

Yasushi Okuda

Nobuyuki Tamura

Hirotsugu Honda

A memory transistor and a select transistor are disposed side by side on a semiconductor substrate between source/drain diffusion layers thereof, with an intermediate diffusion layer interposed therebetween. The memory transistor includes: a gate insulating film having such a thickness as to allow tunneling current to pass therethrough; a floating gate electrode; an interelectrode insulating film; and a control gate electrode. The select transistor includes a gate insulating film and a select gate electrode. Tunneling current, allowing electrons to pass through the gate insulating film under the floating gate electrode, is utilized during the removal and injection of electrons from/into the floating gate electrode. As a result, higher reliability can be attained and rewriting can be performed at a lower voltage. Also, since the select transistor is provided, reading can also be performed at a lower voltage. Improvement of reliability and rewrite and read operations at respective lower voltages are realized for a nonvolatile semiconductor memory device, in which a memory cell includes a floating gate electrode and a control gate electrode.

Nonvolatile semiconductor memory device and method for driving the same

A semiconductor device providing an improved effect of suppressing variation with time of reverse breakdown voltage applied to PN junction, particularly, a voltage-regulator device, is provided. The semiconductor device includes an impurity diffusion layer formed on a surface of a certain-conductivity-type semiconductor substrate or well, the impurity diffusion layer having a conductivity opposite to that of the semiconductor substrate or well, and a device separating insulation film formed at a distance from the impurity diffusion layer, and a distance between an end of the impurity diffusion layer and an end of the device separating insulation film is defined to be not less than 1.2 &mgr;m.

Semiconductor device having a voltage-regulator device

A memory transistor and a select transistor are disposed side by side on a semiconductor substrate between source/drain diffusion layers thereof, with an intermediate diffusion layer interposed therebetween. The memory transistor includes: a gate insulating film having such a thickness as to allow tunneling current to pass therethrough; a floating gate electrode; an interelectrode insulating film; and a control gate electrode. The select transistor includes a gate insulating film and a select gate electrode. Tunneling current, allowing electrons to pass through the gate insulating film under the floating gate electrode, is utilized during the removal and injection of electrons from/into the floating gate electrode. As a result, higher reliability can be attained and rewriting can be performed at a lower volt age. Also, since the select transistor is provided, reading c an also be performed at a lower voltage. Improvement of reliability and rewrite and read operations at respective lower voltages are realized for a nonvolatile semiconductor memory device, in which a memory cell includes a floating gate electrode and a control gate electrode.

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Kyoto, Japan

Masafumi Doi