KR20070079647A - Method of manufacturing a phase-changeable memory device - Google Patents

Abstract

A method for manufacturing a phase-changeable memory device is provided to simplify a manufacturing process by forming a contact electrode with a first CMP process. A metal layer pattern(120) separated by a trench is formed by etching a metal layer exposed by a hard mask(122). A dielectric layer pattern(126) is formed to bury the trench. A first insulating layer(128) and a second insulating layer are sequentially formed to cover the hard mask and the dielectric layer pattern. An opening is formed to expose a surface of the metal layer pattern. A conductive layer is formed on the second insulating layer to bury the opening. The conductive layer is electrically connected to the metal layer pattern. A contact electrode(140) is formed by performing a CMP process for the resultant. A phase-changeable material layer is formed on the first insulating layer to be electrically connected to the contact electrode. An upper electrode is formed on the phase-changeable material layer.

Description

METHODS OF MANUFACTURING A PHASE-CHANGEABLE MEMORY DEVICE}

1 is a cross-sectional view schematically showing a phase change memory device disclosed in the above-mentioned publications.

2 to 8 are process cross-sectional views illustrating a method of manufacturing a phase change memory device according to an embodiment of the present invention.

<Description of the code | symbol about the principal part of drawing>

100 semiconductor substrate 120 metal film pattern

122: hard mask 124: trench

126 dielectric layer pattern 128 first insulating film

130: second insulating film 132: opening

140: contact electrode 150: phase change material film

160: upper electrode

The present invention relates to a method of manufacturing a memory device, and more particularly, to a method of manufacturing a phase change memory device manufactured using a phase change material according to heat.

Examples of semiconductor memory devices widely used in recent years include DRAM, SRAM, Flash memory, and the like. Such semiconductor devices may be largely divided into volatile memory devices and nonvolatile memory devices according to the presence or absence of data when the power supply is interrupted. Memory devices used for data storage of digital cameras, MP3 players and mobile phones are mainly used by nonvolatile memory devices, especially flash memory, to store data even in the absence of a power supply.

However, since a flash memory is not a random access memory (RAM), a new semiconductor device has been required because a lot of time is required to read or write data. As such new next-generation semiconductor devices, ferro-electric RAM (FRAM), magnetic RAM (MRAM), phase change memory devices: phase-change RAM (PRAM), and the like have been proposed.

Among them, a phase change material in which a phase change memory device changes in phase between a crystal structure and an amorphous structure depends on heat provided thereto. Examples of phase change materials that are commonly applied include chalcogenides composed of germanium (Ge), antimony (Sb), and tellurium (Te).

In particular, the phase change memory device has a structure in which a current flows through the phase change material film to provide heat to the phase change material. That is, it has a structure which can change the crystal state of a chalcogenide compound depending on the magnitude | size of supply current and supply time. Since the phase change memory device has a different magnitude of resistance depending on the crystal state of the phase change material (the crystal state is low in resistance and the amorphous state is high in resistance), logic information may be determined by detecting a difference in resistance.

1 is a cross-sectional view schematically illustrating a phase change memory device having the above-described characteristics.

Referring to FIG. 1, the phase change memory device includes a substrate 10, a metal film pattern 12, a contact electrode 22, a phase change material film 30, and an upper electrode 40. Here, the contact electrode 22 is interposed in an opening penetrating through the hard mask 14 and the first insulating layer 18 resumed between the metal film pattern 12 and the phase change material film 30. The film pattern 12 and the phase change material film 30 are electrically connected to each other. In the opening, a spacer 20 for adjusting the design rule of the contact electrode is formed.

In order to form the contact electrode 22 of the phase change memory device having the above-described structure, the first insulating film 18 and the second insulating film (not shown) covering the hard mask 14 existing on the metal film pattern 12 are formed. To form sequentially. Subsequently, an opening penetrating the hard mask, the first insulating film, and the second insulating film is formed, and then a conductive film electrically connected to the metal film pattern is formed while filling the opening. Subsequently, a first chemical mechanical polishing is performed to form a preliminary contact electrode until the surface of the second insulating film is exposed, and then an etching process is performed to remove the second insulating film. Next, the upper part of the preliminary contact electrode protruding from the surface of the first insulating film is subjected to second chemical mechanical polishing. As a result, the contact electrode is completed.

However, the above-described method of forming the contact electrode requires a further chemical mechanical polishing process and a process of etching a separate second insulating film, which leads to an increase in time and cost of the phase change memory device manufacturing process. .

An object of the present invention for solving the above problems is to provide a method of a phase change memory device capable of forming a contact electrode only by a primary chemical mechanical polishing process.

In order to manufacture the phase change memory device according to the exemplary embodiment of the present invention, the metal film exposed to the hard mask is etched to form a metal film pattern separated by a trench. A dielectric layer pattern is formed to bury the trench. A first insulating film and a second insulating film covering the hard mask and the dielectric film pattern are sequentially formed. An opening is formed through the hard mask, the first insulating film, and the second insulating film to expose the surface of the metal film pattern. A conductive film electrically connected to the metal film pattern while being filled in the opening is formed on the second insulating film. The resultant is mechanically polished until the surface of the first insulating film is exposed to form the contact electrode. A phase change material film is formed on the first insulating film and electrically connected to the contact electrode. An upper electrode is then formed on the phase change material film. As a result, a phase change memory device is completed.

When the first insulating film includes silicon oxynitride, the second insulating film preferably includes silicon oxide, and when the first insulating film includes silicon nitride, the second insulating film preferably includes silicon oxynitride. Do. In addition, a third insulating film made of silicon oxide may be formed between the first insulating film and the second insulating film.

As described above, the present invention can significantly reduce the manufacturing process of the contact electrode because the second insulating film is removed together with the conductive film during the chemical mechanical polishing process of the conductive film to form the contact electrode.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided to ensure that the disclosed subject matter is thorough and complete, and that the spirit of the present invention to those skilled in the art will fully convey.

In the accompanying drawings, the dimensions of substrates, layers (films), regions, openings, contacts, electrodes, patterns, or structures are shown in larger scale than actual for clarity of the invention. In the present invention, each layer (region), region, opening, contact, electrode, pattern or structure is "on", "on bottom" "on top" or "side" of the substrate, each layer (film) or patterns. Where each layer (film), region, opening, contact, pattern or structure is formed directly over or below a substrate, each layer (film), region, pad, electrode or pattern Alternatively, other layers (films), other regions, other patterns, openings, contacts or other structures may be additionally formed on the substrate. In addition, where each layer (film), region, pattern, electrode or structure is referred to as "first", "second", "third" or top, bottom, it is not intended to limit these members but only each layer. (Film), areas, pads, openings, patterns or structures to distinguish them. Thus, "first", "second" and / or "third" may be used selectively or interchangeably for each layer (film), region, trench, pattern or structure, respectively. In addition, the cleaning and drying generally performed after performing the etching process or the stripping process mentioned in the embodiment of the present invention may be omitted since it is obvious to those skilled in the art.

2 to 8 are process cross-sectional views illustrating a method of manufacturing a phase change memory device according to an embodiment of the present invention.

Referring to FIG. 2, the metal layer pattern 120 separated by the trench 124 and corresponding to the lower electrode is prepared. The metal film pattern 120 is a member formed on the semiconductor substrate 100 and is a transistor for applying an electrical signal between the metal film pattern 120 and the semiconductor substrate, a bit line for connecting an electrical signal, and conductive material. A structure such as a wiring is interposed. The hard mask 122 is formed on the metal layer pattern 120 mentioned above.

Specifically, a silicon oxide film is formed on the substrate 100 on which lower structures (not shown), such as an isolation layer, a contact region, a transistor, a bit line, and a contact plug, are formed. The silicon oxide film may be formed using an oxide such as BPSG and TEOS. The silicon oxide film may be formed using a chemical vapor deposition process, a plasma enhanced chemical vapor deposition (PE-CVD) process, an atomic layer deposition process, or a high density plasma chemical vapor deposition (HDP-CVD) process.

A metal film (not shown) is formed on the silicon oxide film. The metal film includes tungsten (W), aluminum (Al), copper (Cu), titanium (Ti), tantalum (Ta), tantalum nitride (TaN), and the like, and may be formed by performing a plasma chemical vapor deposition or sputtering process. Can be. Subsequently, a hard mask 122 made of silicon nitride is formed on the metal film. The hard mask 122 is formed by forming a silicon nitride film on the metal film and then performing a photolithography process. Thereafter, the metal film exposed to the hard mask 122 is dry-etched to form the metal film pattern 120 separated from each other by the trench 124.

Referring to FIG. 4, after forming the dielectric layer pattern 126 to bury the trench 124, the first insulating layer 128 and the second insulating layer 130 covering the resultant are sequentially formed.

Specifically, a dielectric film (not shown) covering the hard mask 122 is formed while the trench is buried. The dielectric layer may be formed using silicon oxide such as USG, PSG, HSG, SOG, or the like. Thereafter, an etch back process is performed until the surface of the hard mask is exposed to form the dielectric layer pattern 126.

Subsequently, the first insulating layer 128 and the second insulating layer 130 covering the surfaces of the dielectric layer pattern 126 and the hard mask 122 are sequentially formed.

As an example, when the first insulating film 128 is a silicon oxide film made of silicon oxide, the second insulating film 130 may be a silicon oxynitride film made of silicon oxynitride. As another example, when the first insulating film 128 is a silicon nitride film made of silicon nitride, the second insulating film 130 may be a silicon oxynitride film made of silicon oxynitride. As another example, a silicon oxide film, which is a third insulating film (not shown), may be interposed between the first insulating film 128 and the second insulating film 130.

Referring to FIG. 5, an opening 132 is formed through the hard mask 122, the first insulating layer 128, and the second insulating layer 130 to expose the surface of the metal layer pattern 120.

Specifically, after the photoresist pattern (not shown) is formed on the second insulating layer 130, the second insulating layer 130, the first insulating layer 128, and the hard mask 122 exposed to the photoresist pattern are sequentially formed. Dry etching to form an opening 132 to expose the surface of the metal film pattern 120. Due to the formation of the opening 132, the second insulating film is formed by the second insulating film 130 penetrated by the opening, and the first insulating film is formed by the first insulating film 128 penetrating by the opening 132. Is formed. Thereafter, a plasma ashing and stripping process is performed to remove the photoresist pattern.

Referring to FIG. 6, a conductive film 138 for contact electrodes is formed to bury openings 132 penetrating through the hard mask 122, the first insulating film 128, and the second insulating film 130. The conductive film for the contact electrode may be formed using a metal such as tantalum, copper, tungsten, titanium, aluminum, or a nitride thereof.

For example, before forming the conductive layer, a spacer 135 may be further formed on sidewalls of the opening 132. The spacer 135 includes silicon oxide or silicon nitride, and defines the size of the cross-sectional area of the contact electrode formed in a subsequent process.

Referring to FIG. 7, a contact electrode 140 electrically connected to the metal film pattern 120 is formed.

Specifically, the conductive film 140 and the second insulating film 130 are chemically mechanically polished until the top surface of the first insulating film 150 is exposed. As a result, a contact electrode 160 is electrically connected to the metal layer pattern 120 and embedded in the opening 132. Here, since the current provided through the metal film pattern 120 has a narrow cross-sectional area, the contact electrode 140 generates a large heat with a small current in the materialization material layer to facilitate phase change of the phase change material. It plays a role.

Referring to FIG. 8, a phase change material film 150 is formed on the contact electrode 140 and the first insulating film 128. The phase change material film 150 is formed by a sputtering method using a chalcogenide compound.

Here, the chalcogen compound is germanium-antimony-tellurium (GST), arsenic-antimony-tellurium, tin-antimony-tellurium, tin-indium-antimony-tellurium, arsenic-germanium-antimony-tellurium, tantalum , Group 5A elements-antimony-tellurium, tungsten, molybdenum to chromium, etc.-Group 6A elements-antimony-tellurium, group 5A elements-antimony-selenium, group 6A elements-antimony-selenium, etc. do. Preferably, the phase change material film 170 is formed using germanium-antimony-tellurium (GST).

Subsequently, the upper electrode 160 is formed on the phase change material layer 150 using chemical vapor deposition, physical vapor deposition, or atomic layer deposition. The upper electrode 160 is a conductive film formed using a conductive material containing a nitrogen element, a metal, or a metal silicide.

Here, examples of the conductive material containing the nitrogen element include titanium nitride, tantalum nitride, molybdenum nitride, titanium-silicon nitride, titanium-aluminum nitride, titanium-boron nitride, zirconium-silicon nitride, tungsten-silicon nitride, tungsten-boron nitride And zirconium-aluminum nitride, molybdenum-silicon nitride, molybdenum-aluminum nitride, tantalum-silicon nitride, tantalum-aluminum nitride, titanium oxynitride, titanium-aluminum oxynitride, or tungsten oxynitride, tantalum oxynitride, and the like. In addition, any conductive material capable of flowing a sufficient current as a conductor can be used.

As a result, a structure in which a contact electrode 140 connected to the metal layer pattern 120 and a first insulating layer 128, a phase change material layer 150, and an upper electrode 160 through which the contact electrode penetrates are sequentially stacked A phase change memory device having is formed. Thereafter, a third insulating layer may be further formed to insulate the phase change memory device formed adjacent to the phase change memory device.

As described above, in the manufacturing process of the phase change memory device of the present invention, the second insulating film and the conductive film may be removed in a single chemical mechanical polishing process until the surface of the first insulating film is exposed. Therefore, the contact electrode can be manufactured by performing a single chemical mechanical polishing process without performing the two chemical mechanical polishing processes and the separate insulating film removal process, thereby shortening the manufacturing process and reducing the production cost of the phase change memory device. do.

As mentioned above, although preferred embodiment was described about this invention, this invention is not restrict | limited by this, The person of ordinary skill in the art to which this invention belongs is a deformation | transformation in the range which does not deviate from the essential characteristic of this invention. It will be appreciated that the present invention may be implemented in a modified form.

Claims (6)

Etching the metal film exposed to the hard mask to form a metal film pattern separated by the trench; Forming a dielectric layer pattern to bury the trench; Sequentially forming a first insulating film and a second insulating film covering the hard mask and the dielectric film pattern; Forming an opening through the hard mask, the first insulating film, and the second insulating film to expose a surface of the metal film pattern; Forming a conductive film on the second insulating film, the conductive film being electrically connected to the metal film pattern while filling the opening; Chemically polishing the resultant until the surface of the first insulating film is exposed to form the contact electrode; Forming a phase change material film formed on the first insulating film and electrically connected to the contact electrode; And And forming an upper electrode on the phase change material layer. The method of claim 1, wherein the metal pattern is Forming a hard mask on the metal film, the hard mask partially exposing the surface of the metal film; And And etching the metal film exposed to the hard mask to form a phase change memory device. The method of claim 1, wherein the first insulating layer includes silicon oxynitride (SiON), and the second insulating layer includes silicon oxide (SiO 2). The method of claim 1, wherein the first insulating layer includes silicon nitride (SiN) and the second insulating layer includes silicon oxynitride (SiON). 5. The method of claim 4, further comprising forming a third insulating film made of silicon oxide between the first insulating film and the second insulating film. The method of claim 1, further comprising forming an oxide spacer or a nitride spacer in the opening.

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