KR101035145B1 - Phase Change RAM device and method of manufacturing the same - Google Patents

Abstract

The present invention provides a phase change memory device including a phase change layer, an upper electrode, and a bit line in contact with the upper electrode, wherein the upper electrode and the bit line are stacked on the phase change layer.

Description

Phase change RAM device and method of manufacturing the same

The present invention relates to a phase change memory device and a method of manufacturing the same, and more particularly, to a phase change memory device capable of preventing misalignment between the upper electrode and the upper electrode contact and a manufacturing method thereof.

In general, a memory device is classified into a volatile RAM device that loses input information when a power supply is cut off, and a nonvolatile ROM device that maintains input data storage even when a power supply is cut off. do. The volatile RAM devices may include DRAM and SRAM, and the nonvolatile ROM devices may include a flash memory such as EEPROM.

However, the DRAM has a higher charge storage capacity is required, for this purpose, it is difficult to high integration because the electrode surface area must be increased. In addition, the flash memory 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, research on phase change memory (PRAM) having high characteristics and characteristics of the nonvolatile memory device and simplicity of structure is being actively conducted.

The phase change memory device converts a phase change material into an amorphous phase or a crystalline phase using an electrical signal, and is a memory device that stores and reads information using a difference in electrical conductivity.

On the other hand, one of the most important issues in the development of highly integrated phase change memory devices is to secure programming current, and one of the methods is to apply vertical PN diodes as switching devices.

As described above, the phase change memory device using the vertical PN diode has a higher current flow than the CMOS transistor to secure a programming current, and a cell size smaller than that of a DRAM or flash device. Have

FIG. 1 is a cross-sectional view illustrating a conventional phase change memory device using a vertical PN diode as a cell switching device.

A cell switching element 130 made of a vertical PN diode is formed on the semiconductor substrate, and an impurity region is formed in the surface of the semiconductor substrate to electrically connect the cell switching element 130 to the word line 190. (Not shown) is formed. Here, the vertical PN diode which is the cell switching element 130 is composed of a stacked pattern of an N-type silicon film and a P-type silicon film.

Subsequently, a word line contact is formed to connect between the word line 190 and the impurity region in the active region 110. The word line contact is formed by the first contact plug 151 and the second contact plug 152. Are connected to each other in an on-axis form.

Subsequently, a heater 140 serving as a lower electrode is formed on the cell switching element 130 formed of the vertical PN diode, and the phase change layer 160 and the upper electrode 170 are formed on the heater 140. A stacked pattern of the plurality of layers is formed, and a bit line 180 is formed on the upper electrode 170 in a direction perpendicular to the word line 190. The bit line 180 is connected to the upper electrode 170 by an upper electrode contact 171.

On the other hand, the development of such a phase change memory device is still in its infancy and needs many complementary points. As one of the above, a supplementary point for misalignment between the upper electrode contact 171 connecting the bit line 180 and the upper electrode 170 and the upper electrode 170 is also required.

In general, since the upper electrode contact 171 is formed at the same time as the bit line 180, the contact has a height of about 5000 μs. As such, when the height of the upper electrode contact is high, an etching loss may occur in the upper electrode part.

When the upper electrode contact is formed, if a misalignment occurs due to a slight deviation between the upper electrode and the upper electrode contact, the phase change layer portion may be attacked in a subsequent cleaning process. .

As a result, a misalignment phenomenon between the upper electrode 170 and the upper electrode contact 171 may cause a disturbance in current flow formation during phase change, thereby causing a decrease in the yield of the device.

An object of the present invention is to provide a phase change memory device and a method of manufacturing the same, which can fundamentally solve a misalignment phenomenon occurring between an upper electrode and an upper electrode contact.

According to an aspect of the present invention, there is provided a phase change memory device including a phase change layer, an upper electrode, and a bit line in contact with the upper electrode, wherein the upper electrode and the bit line are stacked on the phase change layer. A change memory device is provided.

In addition, the present invention, a phase change film; And a first metal layer and a second metal layer stacked on the phase change layer.

Here, the first metal film is characterized in that the metal film for the upper electrode.

The first metal film is formed of a laminated film of a Ti film and a TiN film.

The second metal film is a metal film for bit lines.

The second metal film is made of an Al film or a Cu film.

In addition, the present invention provides a method of forming a switching device on an active area of a semiconductor substrate; Forming a lower electrode contact on the switching element; Forming a phase change film, a first metal film for an upper electrode, and a metal film for a second bit line on the lower electrode contact in a stack; And forming a word line in contact with the semiconductor substrate according to the direction of the active region.

Here, the switching device is characterized in that the vertical PN diode.

The first metal film for the upper electrode may be formed as a stacked film of a Ti film and a TiN film.

The bit line second metal film is formed of an Al film or a Cu film.

According to an embodiment of the present invention, a metal film is formed on a phase change film, and the lower metal film of the stacked metal films serves as an upper electrode, and the upper metal film plays a role of a bit line. The contact is possible even without forming the upper electrode contact.

Therefore, the present invention can manufacture a phase change memory device that does not require the upper electrode contact, thereby solving the misalignment phenomenon between the upper electrode and the upper electrode contact, it can be expected to improve the yield of the device.

In addition, the present invention can omit the upper electrode contact and the bit line forming process, through this, it can be expected to improve the productivity by the simplification of the process.

According to the present invention, a first metal film and a second metal film are stacked on top of a phase change film so that the first metal film serves as an upper electrode and the second metal film serves as a bit line.

In this case, since the first metal film becomes the upper electrode and the second metal film becomes the bit line, the upper electrode and the bit line can be contacted with each other without forming the upper electrode contact.

Therefore, since the present invention does not have to form an upper electrode contact connecting the upper electrode and the bit line, it is possible to fundamentally solve the misalignment occurring between the upper electrode and the upper electrode contact, so that the yield of the device can be expected to be improved. have.

In addition, the present invention can omit the upper electrode contact and the bit line forming process, through this, it can be expected to improve the productivity by the simplification of the process.

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

2 is a cross-sectional view illustrating a phase change memory device according to an embodiment of the present invention.

As illustrated, the phase change memory device includes a Ti-based first metal film 270 serving as an upper electrode on the phase change film 260, and an upper portion of the first metal film 270. The second metal layer 280 of a low resistance material serving as a bit line is formed.

As such, according to the present invention, the first metal film 270 may be understood as an upper electrode through the first metal film 270 being formed of a Ti-based film, and the second metal film 280 may be low. The second metal film 280 may be understood as a bit line through being formed of an Al film or a Cu film, which is a material of resistance.

Therefore, the present invention is formed in a structure in which the upper electrode and the bit line are in direct contact, so that the process of forming the upper electrode contact connecting the upper electrode and the bit line does not have to be performed.

Therefore, the present invention can simplify the process by skipping the process of forming the upper electrode contact, and also fundamentally solve the misalignment phenomenon between the upper electrode and the upper electrode contact.

3A to 3D are cross-sectional views of processes for describing a method of manufacturing a phase change memory device according to an exemplary embodiment of the present invention.

Referring to FIG. 3A, after forming a first interlayer dielectric layer 221 on a semiconductor substrate 200 including an active region 210, vertical PNs that are a plurality of switching elements in the first interlayer dielectric layer 221. The diode 230 is formed.

Referring to FIG. 3B, after the second interlayer insulating layer 222 is formed on the first interlayer insulating layer 221 including the vertical PN diode 230, the vertical PN in the second interlayer insulating layer 222 is formed. The lower electrode contact 240 in contact with the diode 230 is formed.

The lower electrode contact 240 serves as a heater, and thus serves as a heat transfer during a subsequent phase change.

Although not shown, the lower electrode contact may not be formed in the contact hole, which is a portion in which the lower electrode contact is formed, and a subsequent phase change layer may be formed in the contact hole. In other words, a process of forming a lower electrode contact by filling a lower electrode material in the contact hole is skipped, and a phase change film having a buried shape is formed in the contact hole by filling a phase change material in the contact hole. Can be.

Thereafter, the second interlayer insulating layer 222 and the first interlayer insulating layer 221 are etched to form a first contact plug 251 that contacts a subsequent word line.

Referring to FIG. 3C, the phase change film 260, the first metal film 270, and the second metal film 280 are sequentially deposited on the second interlayer insulating film 222 including the first contact plug 251. do.

The first metal film 270 is deposited as a stacked film of a Ti film and a TiN film. The second metal film 280 is deposited by using an Al film or a Cu film.

Next, the second metal layer 280, the first metal layer 270, and the phase change layer 260 are etched to contact the lower electrode contact 240 and the phase change layer 260 and the upper electrode agent. A stacked pattern of the first metal film 270 and the second metal film 280 for bit lines is formed.

Here, since the first metal film 270 is formed of a Ti-based film, it serves as an upper electrode, and the second metal film 280 is formed of Al or Cu, which is a low resistance material, and thus serves as a bit line. Will be able to perform

As described above, the present invention forms the first metal film 270, which is a Ti-based film, and the second metal film 280, which is a low resistance material, on the phase change film 260 in a stack, thereby forming a contact during subsequent current flow. It is possible to form a current flow from the second metal film 280 serving as a bit line to the first metal film 270 serving as an upper electrode without using the same.

Therefore, the present invention can be skill in forming a top electrode contact connecting the top electrode and the bit line.

Referring to FIG. 3D, after the third interlayer insulating film 223 is formed to cover the stacked pattern including the phase change film 260, the upper electrode metal film 270, and the bit line metal film 280, A second contact plug 252 is formed in the third interlayer insulating layer 223 to contact the first contact plug 251.

Next, a word line 290 is formed on the semiconductor substrate on which the second contact plug 252 is formed to contact the second contact plug 252 and the first contact plug 251. The word line 290 is formed along the direction of the active region of the semiconductor substrate.

Subsequently, although not shown, a series of subsequent known processes are sequentially performed to manufacture a phase change memory device according to an exemplary embodiment of the present invention.

Meanwhile, in the embodiment of the present invention, the phase change memory device to which the switching element is applied has been illustrated and described. However, the present invention may be applied to the phase change memory device to which the transistor is applied.

As mentioned above, although the present invention has been illustrated and described with reference to specific embodiments, the present invention is not limited thereto, and the following claims are not limited to the scope of the present invention without departing from the spirit and scope of the present invention. It can be easily understood by those skilled in the art that can be modified and modified.

1 is a process cross-sectional view showing a phase change memory device according to the prior art.

Fig. 2 is a sectional view showing a part of the phase change memory device according to the embodiment of the present invention.

3A to 3D are cross-sectional views of processes for describing a method of manufacturing a phase change memory device according to an embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

200: semiconductor substrate 210: active region

221: first interlayer insulating film 222: second interlayer insulating film

223: third interlayer insulating film 230: vertical PN diode

240: lower electrode contact 251: first contact plug

252: second contact plug 260: phase change film

270: first metal film 280: second metal film

290: wordline

Claims (10)

A first interlayer insulating film formed on the active region of the semiconductor substrate; A plurality of switching elements formed in the first interlayer insulating film; A second interlayer insulating film formed on the first interlayer insulating film and the plurality of switching elements; A lower electrode contact formed in the second interlayer insulating layer and in contact with each of the plurality of switching elements; A first contact plug gap-filled by etching the first and second interlayer insulating films; A phase change film stacked on the lower electrode contact, a first metal film for an upper electrode, and a second metal film for a bit line; A third interlayer insulating film formed on the phase change film and the first and second metal films; A second contact plug formed in the third interlayer insulating film and in contact with the first contact plug; A word line formed on the third interlayer insulating layer and the second contact plug to contact the semiconductor substrate; Phase change memory device comprising a. delete delete The method of claim 1, And the first metal film is formed of a laminated film of a Ti film and a TiN film. delete The method of claim 1, And the second metal film is made of an Al film or a Cu film. Forming a first interlayer insulating film on the active region of the semiconductor substrate; Forming a plurality of switching elements in the first interlayer insulating film; Forming a second interlayer insulating film on the first interlayer insulating film and the plurality of switching elements; Forming a bottom electrode contact in contact with each of the plurality of switching elements in the second interlayer insulating film; Etching the first and second interlayer insulating films and gapfilling a first contact plug; Stacking a phase change film, a first metal film for an upper electrode, and a second metal film for a bit line on the lower electrode contact; Forming a third interlayer insulating film on the phase change film and the first and second metal films; Forming a second contact plug in contact with the first contact plug in the third interlayer insulating film; Forming a word line in contact with the semiconductor substrate on the third interlayer insulating layer and the second contact plug; Method for manufacturing a phase change memory device comprising a. The method of claim 7, wherein The switching device is a manufacturing method of a phase change memory device, characterized in that the vertical PN diode. The method of claim 7, wherein And the first metal film for the upper electrode is formed of a laminated film of a Ti film and a TiN film. The method of claim 7, wherein And the second metal film for the bit line is formed of an Al film or a Cu film.

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