KR20060075423A - Phase-change memory device - Google Patents

Abstract

The present invention discloses a phase change memory device capable of improving the current driveability of a transistor. Disclosed is a semiconductor substrate having a device isolation film for isolation between devices; An active region formed in the remaining region except for the device isolation layer; A word line formed on a substrate resultant including the active region; Source / drain regions formed in the substrate on both sides of the word line; An interlayer insulating film formed on the substrate product including the word line; A contact plug formed in the interlayer insulating layer to be electrically connected to a source / drain region; A phase change film formed on the substrate product including the contact plug; And an upper electrode formed on the phase conversion film, wherein the word line has a narrow width of the word line in an active region to improve current drive characteristics of the transistor, and a word in the remaining regions. The width of the line is formed wide.

Description

 Phase change memory device {PHASE-CHANGE MEMORY DEVICE}

1 is a diagram for explaining a conventional phase change memory device.

2 is a plan view for explaining a phase change memory device according to an embodiment of the present invention.

3 is a plane for explaining a phase change memory device according to another embodiment of the present invention;

Explanation of symbols on the main parts of the drawings

21 semiconductor substrate 22 device isolation film

23: active area 24: word line

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phase change memory element, and more particularly, to a phase change memory element capable of improving current drive characteristics of a transistor.

Generally, a memory device is a volatile random access memory (RAM) device that loses input information when the power is cut off, and a ROM that keeps the input data stored even when the power is cut off. ) Are largely divided into elements. The volatile RAM devices may include DRAM and SRAM, and the nonvolatile ROM devices may include flash memory devices such as EEPROM (Elecrtically Erasable and Programmable ROM). have.

However, although the DRAM is a very good memory device as is well known, high charge storage capability is required for periodic refresh operation, and for this purpose, it is difficult to achieve high integration since the electrode surface area must be increased. In addition, the flash memory device requires a higher operating voltage than a power supply voltage in connection with a structure in which two gates are stacked, and thus requires a separate boost circuit to form a voltage required for write and erase operations. Therefore, there is a difficulty in high integration.

Accordingly, many studies have been conducted to develop new memory devices having characteristics of non-volatile memory devices and simple structures. For example, a phase change RAM device is proposed. It became.

The phase change memory device uses a difference in resistance between crystalline and amorphous phases because a phase change film interposed between the electrodes through a current flow between the lower electrode and the upper electrode occurs from a crystal state to an amorphous state. It is a storage element for determining the information stored in the.

In other words, the phase-conversion memory device uses a chalcogenide film as a phase-conversion film, which is a compound film composed of germanium (Ge), stevidium (Sb), and tellurium (Te). GST film), a phase change occurs between an amorphous state and a crystalline state by an applied current, that is, Joule heat, wherein the resistivity of the phase change film having an amorphous state is in a crystalline state. Since it is higher than the specific resistance of the phase change film having a value, the current flowing through the phase change film is sensed in the read mode to determine whether the information stored in the phase change memory cell is logic '1' or logic '0'.

1 is a diagram for explaining a conventional phase change memory device.

As shown in FIG. 1, the conventional phase change memory device forms an interlayer insulating film 5 on a semiconductor substrate 1 including a lower electrode 3. Next, the interlayer insulating layer 5 is etched to form the contact plug 7 electrically connected to the source regions, and then the phase change layer 9 is formed on the substrate product including the contact plug 7. Subsequently, an upper electrode 11 is formed on the phase conversion film 9.

When a voltage is applied to program the phase change memory cell, heat is generated at the interface between the phase change film 9 and the contact plug 7 to change the portion 9a of the phase change film into an amorphous state. The heat of the edge C of the phase conversion film 9 and the contact plug 7 may diffuse into the surrounding interlayer insulating film 7 and may not be a temperature necessary for changing the state. As a result, when the phase conversion film is amorphous, abnormal regions in which the edge of the phase conversion film 9 is not amorphous may be generated.

On the other hand, in the phase conversion memory device, a current of 1 mA or more is required for stable phase change of the phase conversion film. Accordingly, the current driveability of the transistor formed in the cell region should be improved. However, the conventional phase change memory device has a problem of low current driveability of a transistor formed in a cell region.

Accordingly, an object of the present invention is to provide a phase change memory device capable of improving the current drive characteristics of a transistor, which is devised to solve the above problems.

The present invention for achieving the above object, a semiconductor substrate provided with a device isolation film for isolation between devices; An active region formed in the remaining region except for the device isolation layer; A word line formed on a substrate resultant including the active region; Source / drain regions formed in the substrate on both sides of the word line; An interlayer insulating film formed on the substrate product including the word line; A contact plug formed in the interlayer insulating layer to be electrically connected to a source / drain region; A phase change film formed on the substrate product including the contact plug; And an upper electrode formed on the phase conversion film, wherein the word line has a narrow width of the word line in an active region to improve current drive characteristics of the transistor, and a word in the remaining regions. The width of the line is formed wide.

Here, the device isolation film is formed in I shape, T shape and Z shape.

The word line is formed in an I shape.

The contact plug and the upper electrode may be made of a polysilicon film or a metal film.

(Example)

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a plan view illustrating a phase change memory device according to an exemplary embodiment of the present invention.

As shown in Fig. 2, in the phase change memory device of the present invention, an element isolation film 22 for inter-element isolation is formed on a semiconductor substrate. The device isolation layer 22 may be formed in an I shape, a T shape, and a Z shape. In this case, the remaining region except for the device isolation layer 22 becomes the active region 23. The word line 24 is formed on the substrate product including the active region 23. In this case, the word line is formed of a polysilicon film or a metal film. Here, in order to improve the current driving characteristics of the transistor, the word line 24 has a narrow width of the word line in the active region, and a wide width of the word line in the remaining region.

The thickness is thin, and the word line is thick in the remaining areas.

When the word line is formed thin in the active region on the substrate, and the word line is formed thick in the remaining region, the voltage drop of the transistor can be prevented, so that the current structure of the transistor formed in the cell region can be prevented. Dynamic characteristics can be improved.

Source / drain regions (not shown) are formed in the substrates on both sides of the word line 24, and an interlayer insulating film (not shown) is formed on the substrate product including the word lines 24, and source / drain regions are formed in the interlayer insulating film. Contact plugs (not shown) are formed that are electrically connected to the areas. A phase conversion film (not shown) is formed on a substrate resultant including the contact plug, and an upper electrode is formed on the phase conversion film. In this case, the contact plug and the upper electrode are formed of a polysilicon film or a metal film.

3 is a plan view illustrating a phase change memory device according to another exemplary embodiment of the present invention, and an isolation layer 32 for isolation between devices is formed on the semiconductor substrate 31. In this case, the remaining region except for the device isolation layer 32 becomes the active region 33. The word line 34 is formed on the substrate product including the active region 33. In this case, the word line 34 is formed in an I shape, and in order to improve the current driving characteristics of the transistor, the word line has a thin thickness in the active region, and the word line has a thick thickness in the remaining regions.

In the above, the present invention has been described with reference to some examples, but the present invention is not limited thereto, and a person of ordinary skill in the art may make many modifications and variations without departing from the spirit of the present invention. I will understand.

As described above, the phase change memory device according to the present invention has a narrow width of the word line in the active region on the substrate and a wide width of the word line in the remaining region, thereby preventing the voltage drop of the transistor. For this reason, the current driveability of the transistor formed in the cell region can be improved.

Claims (4)

A semiconductor substrate having a device isolation film for isolation between devices; An active region formed in the remaining region except for the device isolation layer; A word line formed on a substrate resultant including the active region; Source / drain regions formed in the substrate on both sides of the word line; An interlayer insulating film formed on the substrate product including the word line; A contact plug formed in the interlayer insulating layer to be electrically connected to a source / drain region; A phase change film formed on the substrate product including the contact plug; And an upper electrode formed on the phase change film; And the word line has a narrow width of the word line in the active region and a wide width of the word line in the remaining region in order to improve current driving characteristics of the transistor. The phase change memory device of claim 1, wherein the device isolation layer is formed in an I shape, a T shape, and a Z shape. The phase change memory device of claim 1, wherein the word line is formed in an I shape. The phase change memory device as claimed in claim 1, wherein the contact plug and the upper electrode are made of a polysilicon film or a metal film.

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