KR100931966B1 - Phase change structure and its formation method - Google Patents

Abstract

Phase change structures with reduced amounts of defects and methods for making the same are disclosed. First, the laminated composite film (i) forms a phase change film containing a chalcogenide (ii) forms an etch stopper film having a first etch rate with respect to the first etching material containing chlorine on the phase change film, (iii ) By forming a conductive film having a second etching rate greater than the first etching rate with respect to the first etching material on the etch stop layer. The conductive layer is etched using the first etching material to form the upper electrode. The etch stop layer and the phase change layer are etched with the second etching material containing little chlorine to form an etch stop pattern and a phase change pattern. According to the present invention, the phase change pattern located between the lower electrode and the etch stop pattern has a side portion and an upper surface portion with few defects.

Description

Phase changeable structure and method of forming the same

1 is a cross-sectional view illustrating a phase change structure having conventional defects.

2 is a cross-sectional view showing a phase change structure according to an embodiment of the present invention.

3 to 5 are cross-sectional views illustrating a method of forming the phase change structure shown in FIG. 2.

Explanation of symbols on the main parts of the drawings

10 hole 100 insulating film

200: lower electrode 300: phase change film

310: phase change pattern 330: etch stop pattern

350: etch stop film 400: conductive film

410: upper electrode 500: mask pattern

The present invention relates to a phase change structure and a method of forming the same. More particularly, the present invention relates to a phase change structure having reduced defects and a method of forming the same.

Nonvolatile memory devices made of a phase change structure have recently been of great interest. Referring to FIG. 1, a phase change structure generally includes a lower electrode 200, a phase change pattern 310, and an upper electrode 410 formed in a substrate (eg, an insulating layer). The phase change pattern may be formed by etching the phase change film using a mask pattern. The phase change pattern is generally located between the lower electrode and the upper electrode and the phase change pattern may include a chalcogenide.

In general, since a predetermined current generated by the voltage difference generated between the lower electrode and the upper electrode is supplied to the phase change pattern, the resistance of the phase change pattern is relatively low in a single crystal state where the resistance is relatively low. Change to a high amorphous state. Also, when the current supplied to the phase change pattern is reduced or removed, the phase of the phase change pattern changes from an amorphous state to a single crystal state.

In general, after the conductive material is deposited on the phase change film and the phase change film to form a stacked composite material film, a first etching process is performed on the conductive material to form an upper electrode. Thereafter, a second etching process is performed on the phase change film to form a phase change pattern.

When using a conventional etching material (eg, chlorine-containing material) in the first etching process for forming the upper electrode, there is a problem that defects beyond the allowable value occur in the upper surface portion of the phase change pattern in contact with the upper electrode. In addition, when using a conventional etching material (for example, chlorine-containing material) in the second etching process for forming a phase change pattern, at the interface between the phase change pattern and the upper electrode and / or the side portion of the phase change pattern There is a problem that more than allowable defects occur. This is presumably because chlorine remains at the side portion of the phase change pattern or at the interface between the phase change pattern and the upper electrode. Or it is presumed that the remaining chlorine residues or by-products thereof contribute to the formation of defects such as erosion in subsequent processes.

Examples of typical defects that may be formed are shown in FIG. 1. Defects may occur between the phase change pattern 310 and the upper electrode 410 as described with reference 302 in one or both portions of the phase change structure. Defects may also occur in terms of the phase change pattern 301 as indicated at 304 and 306. In addition, defects may be formed between the phase change pattern 310 and the substrate 100 as indicated by reference numeral 306.

It is an object of the present invention to provide a phase change structure comprising a phase change pattern with few defects.

It is a second object of the present invention to provide a method of manufacturing the above-described phase change structure.

According to an embodiment of the present invention for achieving the first object, the phase change structure is a lower electrode, a phase change pattern formed on the lower electrode, a conductive etch stop pattern formed on the phase change pattern and comprises zirconium and And an upper electrode formed on the conductive etch stop pattern.

The phase change pattern may include chalcogenides. Chalcogenides may include germanium, antimony and tellurium. The conductive layer and the conductive etch stop layer may include titanium nitride and zirconium, respectively.

According to an embodiment of the present invention for achieving the second object, first, a lower electrode is formed. A phase change film including a chalcogenide is formed on the lower electrode. A conductive etch stop layer having a first etch rate with respect to the first etch material including chlorine is formed on the phase change layer. A conductive film having a second etching rate greater than the first etching rate with respect to the first etching material is formed on the etch stop layer. The conductive layer is etched using the first etching material to form the upper electrode. The etch stop layer and the phase change layer are etched with a second etching material substantially free of chlorine to form an etch stop pattern and a phase change pattern.

Chalcogenides may include germanium, antimony and tellurium. The conductive layer and the etch stop layer may include titanium nitride and zirconium, respectively. The first etching material may further include an inert gas including helium, neon, argon, krypton, xenon, radon or a mixture thereof. The first etching material may have a plasma state. The conductive film may be etched in a chamber having a source electrode and a bias electrode. The first power and the second power may be applied to the source electrode and the bias electrode, respectively. The ratio of the first power to the second power may be about 2.5: 1 to about 20: 1. The pressure in the chamber may be about 1 mTorr to about 20 mTorr. The first etching material may include chlorine and argon. The ratio of the flow rate of argon to the flow rate of chlorine may be about 2: 1 to about 5: 1. The second etching material may include helium, neon, argon, krypton, xenon, radon or mixtures thereof. The second etching material may have a plasma state. The second etching material may further include fluorine. Fluorine can be provided from tetrafluoromethane, trifluoromethane, difluoromethane, monofluoromethane or mixtures thereof.

According to the present invention, the phase change pattern located between the lower electrode and the etch stop pattern has a side portion and / or an upper surface portion with few defects.

Hereinafter, with reference to the accompanying drawings will be described in detail with respect to the method of forming a phase change structure according to the preferred embodiments of the present invention, the present invention is not limited to the following embodiments, it is common knowledge in the art Persons having the present invention may implement the present invention in various other forms without departing from the spirit of the present invention. In the accompanying drawings, the dimensions of the components are enlarged than actual for clarity of the invention. When components are referred to as "first," "second," "third," and / or "fourth," they are not intended to limit these components but merely to distinguish them. Thus, "first", "second", "third" and / or "fourth" may be used selectively or interchangeably with respect to the components, respectively. When the first component is referred to as being formed "on" of the second component, the first component may be formed between the first component and the second component as well as when the first component is directly formed on the second component. Three components may be interposed.

Phase change  structure

2 is a cross-sectional view showing a phase change structure according to an embodiment of the present invention.

Referring to FIG. 2, the phase change structure includes an insulating layer 100, a lower electrode 200, a phase change pattern 310, an etch stop pattern 330 including zirconium, and an upper electrode 410. The phase change pattern 310 is positioned on the insulating layer 100 and the lower electrode 200 to be in electrical contact with the lower electrode 200. The etch stop pattern 330 is positioned on the phase change pattern 310. The upper electrode 410 is positioned on the etch stop pattern 330.

The upper electrode 410 may be formed by etching the conductive layer. The conductive layer may be etched with a first etching material including chlorine. The conductive film may include a first conductive material that allows the conductive film to have a first etching rate with respect to the first etching material. The conductive materials of the upper electrode are tungsten, titanium, titanium nitride, tantalum, tantalum nitride, molybdenum nitride, niobium nitride, titanium silicon nitride, aluminum, titanium aluminum nitride, titanium boron nitride, zirconium silicon nitride, tungsten silicon nitride, tungsten boron nitride, Zirconium aluminum nitride, molybdenum silicon nitride, molybdenum aluminum nitride, tantalum silicon nitride, copper, aluminum copper, alloys thereof or combinations thereof. Alternatively the conductive material for forming the upper electrode may preferably comprise titanium nitride.

The etch stop pattern 330 may be formed by etching the etch stop layer with a second etch material having almost no chlorine. The etch stop layer may include a conductive material that allows the etch stop layer to have a second etch rate greater than the first etch rate with respect to the first etch material. When the conductive material included in the upper electrode is titanium nitride, the conductive material included in the etch stop layer may be zirconium.

As described above, the first etching material may include a chlorine-containing compound such as C12 or BC13. In addition, the first etching material may further include helium, neon, argon, krypton, xenon, radon or a mixture thereof as other useful compounds, but is not limited thereto. It is preferable that the first etching material has a plasma state.

As mentioned above, the second etching material contains almost no chlorine. The second etching material may include an inert gas such as helium, neon, argon, krypton, xenon, radon or mixtures thereof. Preferably, the second etching material has a plasma state.

The second etching material may further comprise a fluorine-containing compound and / or a hydrogen-comprising compound. Non-limiting examples of fluorine containing compounds that can be used in this case can be provided from tetrafluoromethane, trifluoromethane, difluoromethane, monofluoromethane or mixtures thereof. Non-limiting examples of hydrogen containing compounds that can be used may be H2, HBr, NH3, N2H4, CxHy (eg CH4) and mixtures thereof. CxHy gases that may be used may be ringed or straight-chained. These additional etching materials can be used with helium, neon, argon, krypton, xenon, radon or mixtures thereof.

The phase change film is etched to form the phase change pattern 310. It is desirable to etch the etch stop layer followed by etching the phase change film in one subsequent etch process. The phase change pattern 310 may be formed by etching the phase change layer with the same second etching material used when etching the etch stop layer. The phase change film 300 includes a chalcogenide. As a non-limiting example, chalcogenides may include germanium (Ge), antimony (Sb) and tellurium (Te), and their atomic ratio may be any ratio.

The insulating film 100 has a hole 10. The insulating film 100 includes an oxide or nitride. For example, the insulating film 100 may be formed of phosphosilicate glass (PSG), boro-phosphosilicate glass (BPSG), undoped silicate glass (USG), spin on glass (SOG), tetra ethyl ortho silicate (TEOS), and PE-TEOS. (Plasma Enhanced-TEOS), FOX (Flowable Oxide), HDP-CVD (High Density Plasma-Chemical Vapor Deposition) oxide or silicon nitride.

The lower electrode 200 is located in the hole 10. The lower electrode 200 may include a metal, a metal nitride, or a mixture thereof. For example, the lower electrode 200 may include tungsten, titanium, titanium nitride, tantalum, tantalum nitride, molybdenum nitride, niobium nitride, titanium silicon nitride, aluminum, titanium aluminum nitride, titanium boron nitride, zirconium silicon nitride, tungsten silicon nitride, Tungsten boron nitride, zirconium aluminum nitride, molybdenum silicon nitride, molybdenum aluminum nitride, tantalum silicon nitride, tantalum aluminum nitride, copper, aluminum copper, these may be formed using alloys or mixtures thereof. Alternatively, the lower electrode 200 may include polysilicon doped with impurities. Here, the top surface of the insulating layer 100 is positioned on the same plane as the top surface of the lower electrode 200.

Phase change  How to Form Structure

3 to 5 are cross-sectional views illustrating a method of manufacturing the phase change structure shown in FIG. 2.

Referring to FIG. 3, a hole 10 is formed in the insulating film 100. The insulating film 100 is formed using an oxide or nitride through known processes. For example, the insulating film 100 may be formed of phosphosilicate glass (PSG), boro-phosphosilicate glass (BPSG), undoped silicate glass (USG), spin on glass (SOG), tetra ethyl ortho silicate (TEOS), and PE-TEOS. (Plasma Enhanced-TEOS), Flowable Oxide (FOX), High Density Plasma-Chemical Vapor Deposition (HDP-CVD) oxide or silicon nitride.

Subsequently, the lower electrode 200 is formed in the hole 10. The lower electrode 200 may be formed using a metal, a metal nitride, or a mixture thereof. For example, the lower electrode 200 may include tungsten, titanium, titanium nitride, tantalum, tantalum nitride, molybdenum nitride, niobium nitride, titanium silicon nitride, aluminum, titanium aluminum nitride, titanium boron nitride, zirconium silicon nitride, tungsten silicon nitride, Tungsten boron nitride, zirconium aluminum nitride, molybdenum silicon nitride, molybdenum aluminum nitride, tantalum silicon nitride, tantalum aluminum nitride, copper, aluminum copper, alloys thereof or mixtures thereof. Alternatively, the lower electrode 200 may include polysilicon doped with impurities. Here, the upper surface of the insulating film 100 of 200 is positioned on the same plane as the upper surface of the lower electrode 200.

Next, the phase change film 300 is formed on the insulating film 100 and the lower electrode 200. The phase change film 300 includes a chalcogenide. Chalcogenides may include germanium (Ge), antimony (Sb) and tellurium (Te).

Thereafter, an etch stop layer 350 is formed on the phase change layer 300. The etch stop layer 350 is formed using a first conductive material that allows the etch stop layer 350 to have a first etch rate with respect to the first etch material including chlorine.

Subsequently, the conductive layer 400 is formed on the conductive etch stop layer 350 using a conductive material for an etch stop layer. The conductive layer 400 is formed using a conductive material for an etch stop layer such that the conductive layer 350 has a second etching rate greater than the first etching rate with respect to the first etching material.

Conductive materials for the upper electrode include tungsten, titanium, titanium nitride, tantalum, tantalum nitride, molybdenum nitride, niobium nitride, titanium silicon nitride, aluminum, titanium aluminum nitride, titanium boron nitride, zirconium silicon nitride, tungsten silicon nitride, tungsten boron nitride, Zirconium aluminum nitride, molybdenum silicon nitride, molybdenum aluminum nitride, tantalum silicon nitride, copper, aluminum copper, alloys thereof or combinations thereof. Alternatively the conductive material for forming the upper electrode may preferably comprise titanium nitride.

For example, when the conductive material for the etch stop layer is zirconium, the conductive material for the upper electrode may be titanium nitride. When the etch stop layer 350 and the conductive layer 400 include zirconium and titanium nitride, respectively, the etch rate of the etch stop layer 350 with respect to the first etched material is greater than that of the first etch material of the conductive layer 400. This is because it is larger than the etching rate for.

The conductive film 400 may be formed using known processes. Non-limiting examples of such processes include sputtering processes, chemical vapor deposition (CVD) processes, electron beam deposition processes, atomic layer deposition (ALD) processes or pulsed lasers. Pulse laser deposition (PLD) process.

Next, a mask pattern 500 is formed on the conductive film 400. The mask pattern 500 may include a material that is hardly removed while the conductive layer 400, the etch stop layer 350, and the phase change layer 300 are etched.

Referring to FIG. 4, a first etching process is performed on the conductive layer 400 using the mask pattern 500 as an etching mask. Therefore, the conductive film 400 is changed into a plurality of upper electrodes 410.

The first etching process may be performed using a first etching material including chlorine containing compounds (eg, Cl 2 and BCl 3). The first etching material may further include other useful etching compounds, including, but not limited to, helium (He: helium), neon (Ne: neon), argon (Ar: argon), krypton (Kr: krypton), And xenon (Xe: Xenon), radon (Rn: radon), or a mixture thereof. When the first etching material further includes helium, neon, argon, krypton, xenon, radon or a mixture thereof, the first etching material may have a plasma state.

The first etching process may be performed in a chamber having a source electrode and a bias electrode. In general, the bias electrode is installed in a chuck located at the bottom of the chamber. The source electrode is located at the top of the chamber. Here the source electrode and the bias electrode are used to make the state of the first material into a plasma.

Specifically, a first electric power and a second electric power are applied to the source electrode and the bias electrode, respectively. When the ratio of the first power to the second power is less than about 2.5: 1, there is a problem that the efficiency of the first etching process is low. On the other hand, when the ratio of the first power to the second power exceeds about 20: 1, there is a problem that it is difficult to effectively control the first etching process. Thus, the ratio of the first power to the second power may be about 2.5: 1 to about 20: 1.

If the pressure of the chamber is less than about 1 mTorr, there is a problem that the efficiency of the first etching process is low. On the other hand, if the pressure of the chamber exceeds 20mTorr, there is a problem that can not effectively control the first etching process. Thus, the pressure in the chamber may be about 1 mTorr to about 20 mTorr.

When the ratio of the flow rate of argon to the flow rate of chlorine is less than about 2: 1, there is a problem that the first etching material is difficult to have a plasma state. On the other hand, when the ratio of the flow rate of argon to the flow rate of chlorine exceeds about 5: 1, there is a problem that the conductive film 400 cannot be etched effectively. Thus, the ratio of the flow rate of argon to the flow rate of chlorine may be about 2: 1 to about 5: 1.

If the first etching material (eg, including nitrogen) is provided to the phase change layer 300 in the first etching process, the first etching material chemically reacts with the phase change layer 300 to remove defects. Generate. Specifically, when the phase change film 300 includes germanium, antimony and tellurium, chlorine excessively reacts with antimony. Therefore, the atomic ratio of the chalcogenide changes undesirably.

However, according to the present invention, in order to prevent the atomic ratio of the chalcogenide from changing undesirably, since the etch stop layer 350 is present under the conductive film 400, the first etching process is performed. The first etching material is not provided to the phase change layer 300. That is, during the first etching process, the etch stop layer 350 physically protects the phase change layer 300. Therefore, the phase change layer 300 is not damaged by the first etching material.

In addition, since the etch stop layer 350 is present under the conductive layer 400, the first etching process may be performed until sufficient bridges that may be formed between the upper electrodes 410 are removed. have.

Referring to FIG. 5, a second etching process using a second etching material containing almost no chlorine in the etching stop layer 350 and the phase change layer 300 is performed. Therefore, the etch stop layer 350 and the phase change layer 300 are changed to the etch stop pattern 330 and the phase change pattern 310. The etch stop pattern 330 and the phase change pattern 310 are positioned between the upper electrode 410 and the lower electrode 200.

As described above, when the second etching material includes chlorine, chlorine chemically reacts with the phase change film 300 to generate defects. That is, defects are generated in the side portion of the phase change pattern 310. Therefore, the size of the side portion is reduced.

Specifically, when the phase change film 300 includes germanium, antimony and tellurium, chlorine excessively reacts with antimony to reduce the atomic percentage of antimony. As a result, the second etching material preferably does not contain chlorine.

The second etching material may further include an inert gas consisting of helium, neon, argon, krypton, xenon, radon or a mixture thereof. The second etching material preferably has a plasma state.

The second etching material may further comprise a fluorine containing compound and / or a hydrogen-containing compound. Non-limiting examples of fluorine containing compounds that can be used in this case can be provided from tetrafluoromethane, trifluoromethane, difluoromethane, monofluoromethane or mixtures thereof. Non-limiting examples of hydrogen containing compounds that can be used may be H2, HBr, NH3, N2H4, CxHy (eg CH4) and mixtures thereof. CxHy gases that may be used may be ringed or straight-chained. These additional etching materials can be used with helium, neon, argon, krypton, xenon, radon or mixtures thereof.

First Experimental Example

The chamber was prepared. At the bottom of the chamber was a chuck with a bias electrode. At the top of the chamber was a source electrode. The titanium nitride film was then placed on the chuck. In this example, the chuck was used to replace the wafer.

The pressure in the chamber was about 15 mTorr. The first etchant was introduced into the chamber. The first etchant included argon and chlorine. At this time, the ratio of the flow rate of argon to the flow rate of chlorine was about 3.3: 1. Specifically, the flow rate of argon and the flow rate of chlorine were about 100 Sccm and about 30 Sccm, respectively.

The first power and the second power were applied to the source electrode and the bias electrode, respectively. The ratio of the first power to the second power was about 13.3: 1. Specifically, the first power and the second power were about 1,000 Watts and about 75 Watts, respectively. Here, because of the first and second powers, the first material had a plasma state.

Subsequently, the titanium nitride layer was etched using the first etching material. The etch rate of the titanium nitride film was about 33.4 Å / sec.

Thereafter, the titanium nitride film was removed from the chamber. The zirconium film was placed on the chuck of the chamber. The zirconium film was etched under the same conditions as those used when etching the titanium nitride film. At this time, the etching rate of the zirconium film was about 1.19 dl / sec.

That is, the ratio of the etching rate of the titanium nitride film to the etching rate of the zirconium film was about 28.1: 1. Since the ratio of the etch rate of the titanium nitride film to the etch rate of the zirconium film is relatively large, the zirconium film could function as an etch stopper when the titanium well film was etched using the first etching material.

2nd Experimental Example

The chamber was prepared. At the bottom of the chamber was a chuck with a bias electrode. The source electrode is located at the top of the chamber. The titanium nitride film was then placed on the chuck. In this example, the chuck was used to replace the wafer.

The pressure in the chamber was about 10 mTorr. The first etchant was introduced into the chamber. The first etchant included argon and chlorine. At this time, the ratio of the flow rate of argon to the flow rate of chlorine was about 3: 1. Specifically, the flow rate of argon and the flow rate of chlorine were about 60 Sccm and about 20 Sccm, respectively.

The first power and the second power were applied to the source electrode and the bias electrode, respectively. The ratio of the first power to the second power was about 18.7: 1. Specifically, the first power and the second power were about 14,00 Watts and about 75 Watts, respectively. Here, because of the first and second powers, the first material had a plasma state.

Subsequently, the titanium nitride layer was etched using the first etching material. The etch rate of the titanium nitride film was about 21 kW / sec.

Thereafter, the titanium nitride film was removed from the chamber. The zirconium film was placed on the chuck of the chamber. Zirconium films were etched under the same conditions used to etch titanium nitride films. At this time, the etching rate of the zirconium film was about 1.2 mW / sec.

That is, the ratio of the etching rate of the titanium nitride film to the etching rate of the zirconium film was about 17.5: 1. Since the ratio of the etch rate of the titanium nitride film to the etch rate of the zirconium film is relatively large, the zirconium film could function as an etch stopper when the titanium well film was etched using the first etching material.

According to the present invention, the phase change pattern located between the lower electrode and the etch stop pattern has a side portion and an upper surface portion with few defects.

Although described with reference to the preferred embodiments of the present invention as described above, those skilled in the art will be variously modified and modified within the scope of the present invention without departing from the spirit and scope of the invention described in the claims below. It will be appreciated that it can be changed.

Claims (19)

delete delete delete delete delete Forming a lower electrode; Forming a phase change film including a chalcogenide on the lower electrode; Forming an etch stop layer having a first etch rate with respect to the first etch material including chlorine on the phase change layer; Forming a conductive layer on the etch stop layer, the conductive layer having a second etch rate greater than the first etch rate with respect to the first etch material; Etching the conductive layer using the first etching material to form an upper electrode; And Etching the etch stop layer and the phase change layer with a second etch material comprising helium, neon, argon, krypton, xenon, radon or a mixture thereof to form an etch stop pattern and a phase change pattern Forming method. 7. The method of claim 6, wherein the chalcogenide comprises germanium, antimony and tellurium. The method of claim 6, wherein the conductive film is tungsten, titanium, titanium nitride, tantalum, tantalum nitride, molybdenum nitride, niobium nitride, titanium silicon nitride, aluminum, titanium aluminum nitride, titanium boron nitride, zirconium silicon nitride, tungsten silicon nitride, tungsten A method of forming a phase change structure comprising a conductive material that is boron nitride, zirconium aluminum nitride, molybdenum silicon nitride, molybdenum aluminum nitride, tantalum silicon nitride, copper, aluminum copper, alloys thereof, or a combination thereof. The method of claim 8, wherein the conductive layer and the etch stop layer comprise titanium nitride and zirconium, respectively. The method of claim 6, wherein the first etching material comprises helium, neon, argon, krypton, xenon, radon or mixtures thereof, The method of claim 1, wherein the first etching material has a plasma state. The method of claim 10, wherein the etching of the conductive film is performed in a chamber having a source electrode and a bias electrode. A first power and a second power are respectively applied to the source electrode and the bias electrode, And a ratio of the first power to the second power is 2.5: 1 to 20: 1. 12. The method of claim 11 wherein the pressure in the chamber is between 1 mTorr and 20 mTorr. The method of claim 11, wherein the first etching material comprises chlorine and argon, The ratio of the flow rate of argon to the flow rate of chlorine is 2: 1 to 5: 1 method of forming a phase change structure. The method of claim 6, wherein the second etching material has a plasma state. The method of claim 6, wherein the second etching material further comprises a fluorine-containing compound. The method of claim 15, wherein the fluorine containing compound is provided from tetrafluoromethane, trifluoromethane, difluoromethane, monofluoromethane or mixtures thereof. The method of claim 6, wherein the second etching material further comprises a hydrogen-containing compound. 18. The method of claim 17, wherein the hydrogen containing compound is selected from the group consisting of H2, HBr, NH3, N2H2, CH4, and combinations thereof. The method of claim 6, wherein the second etching material is helium, neon, argon, krypton, xenon, radon, tetrafluoromethane, trifluoromethane, difluoromethane, monofluoromethane, H2, HBr, NH3, N2H2, CH4 and Phase change structure formation method characterized in that the compound selected from a combination of these.

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