Matsushita Electric Industrial Co., Ltd.

Matsushita Electronics Corporation

Yoshinori Odake

Yasushi Okuda

Toshiki Mori

Akira Asai

Takahiko Hashidzume

Takashi Maejima

Hidenori Tanaka

Mitsuyoshi Andou

Ichirou Nakao

Teruhito Ohnishi

Fumihiko Noro

Ichiro Nakao

Minoru Fujii

Toshimoto Kubota

Youhei Ichikawa

A first conductive film for forming a plurality of word lines is formed in a memory cell array formation region of a semiconductor substrate for a nonvolatile semiconductor memory device, and a second conductive film is formed in a semiconductor device formation region of the semiconductor substrate. Next, openings are formed in the first conductive film by a first dry etching process such that the word lines in the memory cell array formation region are located apart from one another. Thereafter, sidewall insulating films for the word lines are formed in the openings. Next, parts of the sidewall insulating films located adjacent to the ends of the word lines are removed by wet etching. Next, a part of the first conductive film located around a word line formation region is removed by a second dry etching process. The openings are formed in the first conductive film such that a part of the first conductive film remaining after the formation of the openings is continuous with the second conductive film, which is formed on an active region of the semiconductor substrate located outside the memory cell array formation region so as to be electrically connected to the active region.

Nonvolatile semiconductor memory device and method for fabricating the same

A gate structure composed of a tunnel insulation film, a floating gate electrode, a capacitive insulation film and a control gate electrode is formed on a semiconductor substrate. Then, ion injection adjustment films that are in contact with the floating gate electrode at least on the side surfaces of the floating gate electrode are formed. After injecting impurity ions into the active region beside the gate structure in the semiconductor substrate while using the gate structure and the ion injection adjustment film as masks, the injected impurity ions are diffused thermally by performing heat treatment on the active region. Film thickness of the ion injection adjustment film is selected to a value to prevent the impurity ions from being injected into the tunnel insulation film and allows the impurity ions to reach lower portions of side end of the floating gate electrode in the active region as a result of diffusive scattering of impurity ions in the semiconductor substrate.

Method of fabricating nonvolatile semiconductor memory device

A circuit for testing a nonvolatile semiconductor memory includes a serial connection of flash memory cells as a first memory group. In the serial connection, the gates of the flash memory cells have been connected to each other, and a first one of the cells has its source or drain connected to the source or drain of a second one of the cells when the first and second cells are adjacent to each other.

Nonvolatile semiconductor memory test circuit and method, nonvolatile semiconductor memory and method for fabricating nonvolatile semiconductor memory

A stacked gate portion, including a tunnel insulating film, a floating gate electrode, a capacitive insulating film and a control gate electrode, is formed over a p-type Si substrate. In the p-type Si substrate, n,source/drain layers and n,source/drain layers, each layer containing arsenic, are formed. In the drain region, an n,drain layer, containing phosphorus and overlapping with an entire edge of the stacked gate portion in the gate width direction, and a p layer surrounding the bottoms of the n,and the n,drain layers are provided. In such a structure, an electric field applied between the floating gate electrode and the drain is weakened and the drain-disturb characteristics are improved during writing.

LOCOS layers for defining NMOSFET and PMOSFET forming regions Rn and Rp are formed, and then a protective oxide layer is formed. A first resist layer, opened above the region Rn, is then formed on the protective oxide layer. By using the first resist layer as a mask, ion implantation is performed twice to form a threshold control layer and a P- layer functioning as a punch-through stopper or the like. By using the first resist layer as a mask, the substrate is etched to remove a portion of the protective oxide layer. Then, the first resist layer is removed. These processes are also performed on the region Rp. Then, a gate oxide layer is formed. Thus, it is possible to prevent a foreign impurity, introduced during the ion implantation, from diffusing the surrounding regions when the resist layers are removed. As a result, the properties of the gate oxide layer can be improved.

Semiconductor device and method for producing the same

A method for fabricating a nonvolatile semiconductor memory device having a stacked gate portion, including a tunnel insulating film, a floating gate electrode, a capacitive insulating film and a control gate electrode, formed over a p-type Si substrate. In the p-type Si substrate, n.sup.++ source/drain layers and n.sup.+ source/drain layers, each layer containing arsenic, are formed. In the drain region, an n.sup.- drain layer, containing phosphorus and overlapping with an entire edge of the stacked gate portion in the gate width direction, and a p layer surrounding the bottoms of the n.sup.+ and the n.sup.- drain layers are provided. In such a structure, an electric field applied between the floating gate electrode and the drain is weakened and the drain-disturb characteristics are improved during writing.

Method for fabricating nonvolatile semiconductor memory device

An array of non-volatile memory cells arranged in rows and columns is provided. Each memory cell is composed of a transistor made up of a gate, a source, and drain and a capacitance section. Each memory cell is connected to a row decoder through a wordline, to a column decoder through a bitline, and to a source decoder through a sourceline. Arranged in a path extending from a bitline to a sourceline through a transistor is an anisotropic resistance section, e.g., a diode, exhibiting different voltage-current characteristics for different levels of voltages applied thereacross. Because of such arrangement, leakage current occurring to a deselected memory cell in a reading operation can be reduced or can be eliminated. Read errors due to leakage current can be avoided and the power consumption can be reduced.

Method for driving a non-volatile semiconductor memory

Non-volatile semiconductor memory having an array of non-volatile memory

A non-volatile semiconductor memory cell having a novel structure is provided. The memory cell has a ring-shaped channel region formed on a semiconductor substrate, a drain region formed in a zone surrounded by the channel region, and a source region formed outside the channel region. The cell further includes a first gate insulation layer formed on the substrate in such a manner as to cover the boundary between the channel region and the drain region, a ring-shaped floating gate electrode formed on the first gate insulation layer, a second gate insulation layer formed on the floating gate electrode; and a control gate electrode which is capacitive-coupled with the floating gate via the second gate insulation layer.

Non-volatile semiconductor memory having a ring-shaped floating gate

In a CMOS semiconductor device, low-dose ion implant of p-type impurity and n-type impurity is successively conducted to both n-MOSFET and p-MOSFET after formation of gate electrodes. Thereafter, when source/drain regions are formed at each MOSFET, p.sup.- regions function as local punch through stoppers in the n-MOSFET and n.sup.- regions function as the local punch through stoppers in the p-MOSFET. At this time, respective doses of n-type and p-type impurities are adjusted so that lowerings of threshold values of the channel regions are almost equal to each other. Thus, short channel effect is prevented, while reducing the step of forming two resist masks. With side walls, the CMOS semiconductor device with less short channel effect and high durability to hot carrier is manufactured without increase in the step of forming the resist masks.

Method of manufacturing semiconductor device

A semiconductor device is provided comprising a nonvolatile memory cell through which an LSI and a higher operating speed are achieved. A drain region, an insulating layer partly overlaying the drain region, and a gate electrode formed on the insulating layer are formed on a semiconductor substrate thereby making up a memory cell without a source region. An energy gap between the conduction and valence bands of a semiconductor section including the drain region and the semiconductor substrate is preset to a value corresponding to a first set voltage difference between the drain and the gate. The energy gap between the valence bands (or the conduction bands) of the insulating layer and the semiconductor section at the interface between the semiconductor section and the insulating layer is preset to a value corresponding to a second set voltage difference between the drain and the substrate. Write operations are done by trapping in the insulating layer a charge which has jumped the valence band of the insulating layer at a voltage not less than the second set voltage difference. Read operations are done at a voltage not less than the first set voltage but not more than the second set voltage. Erase operations are done by releasing a charge trapped or by implanting a reverse charge.

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Osaka, Japan

Yoshinori Odake