KR20090036771A - Method of fabricating phase change memory device having a doped phase change material layer - Google Patents

Abstract

A manufacturing method of a phase change memory device is provided to have a large difference of a resistance value between phase change patterns of a reset state and phase change patterns of a set state by forming a phase change material film inside a localized structure such as a contact hole without a void. A substrate having an opening part is loaded in a chamber. A first source gas is supplied to the chamber during t1 time(t1). The first source gas is changed into a plasma state in order to form a Ge film by supplying plasma to the chamber. A second source gas is supplied to the chamber during t3 time(t3). A second material film is formed on a top of a doped Ge film. The second source gas is changed into a plasma state by supplying plasma to the chamber. A plasma doping process of dopant is performed during t4 time(t4) shorter than t3 time. A third source gas is supplied to the chamber during t5 time(t5). A third material film is formed on a top of a doped tellurium film. The third source gas is changed into a plasma state by supplying plasma to the chamber.

Description

Method of fabricating phase change memory device having a doped phase change material layer

The present invention relates to a method of manufacturing a semiconductor device, and more particularly, to a method of manufacturing a phase change memory device having a doped phase change material film.

The semiconductor memory devices may be divided into volatile memory devices and nonvolatile memory devices according to whether data is retained when power supply is interrupted. The nonvolatile memory devices have an advantage that data stored therein is not destroyed even if their power is cut off. Accordingly, the nonvolatile memory device is widely adopted in a mobile communication system and a mobile memory device.

There have been many efforts to develop a new memory device having a nonvolatile memory characteristic and an efficient structure for improving the integration, and a representative of the phase change memory device has been shown. The unit cell of the phase change memory device may include an access device and a data storage element serially connected to the access device. The data storage element has a bottom electrode electrically connected to the access element and a phase change material film in contact with the bottom electrode. The phase change material film is a material film that is electrically switched between an amorphous state and a crystalline state or between various resistance states under the crystalline state, depending on the amount of current provided. .

1 is a partial cross-sectional view schematically showing a conventional phase change memory device.

Referring to FIG. 1, a typical phase change memory device includes a lower interlayer insulating film 12 disposed in a predetermined region on a semiconductor substrate 10, a lower electrode 14 penetrating through the lower interlayer insulating film 12, and the lower interlayer. An upper interlayer insulating film 20 covering the insulating layer 12, a bit line 22 disposed on the upper interlayer insulating film 20, and an upper interlayer insulating film 20 disposed in the upper interlayer insulating film 20 and in contact with the lower electrode 14. A phase change pattern 16 and an upper electrode 18 electrically connecting the phase change pattern 16 to the bit line 22 are provided. In addition, although not shown, the lower electrode 14 is electrically connected to an access element such as a diode or a transistor.

Joule heat at the interface between the phase change pattern 16 and the lower electrode 14 (hereinafter referred to as an 'active contact surface') when a program current flows through the lower electrode 14. Is generated. This joule heat converts a portion of the phase change pattern 16 (hereinafter referred to as a 'transition region') into an amorphous state or crystalline state. For example, by applying a high current to the phase change pattern 16 for a short time, the phase change pattern 16 can be converted to a reset state of the amorphous state (corresponding to storage of logic " 1 "). have. In contrast, by applying a low current to the phase change pattern 16 for a long time, it can be converted to the set state of the crystalline state (corresponding to the storage of logic "0"). In this case, the resistance of the transition region 24 having the reset state is higher than the resistance of the transition region 24 having the set state. Accordingly, by sensing the current flowing through the transition region 24 in the read mode, it is possible to determine whether the information stored in the unit cell of the phase change memory device is logic '1' or logic '0'.

Here, the larger the transition region 20, the larger the reset current and the set current should be. In this case, the access element should be designed to have sufficient current driving capability to supply the currents. However, in order to improve the current driving capability, the area occupied by the access element is increased. In other words, the smaller the transition region 20 is, the better the integration degree of the phase change memory device is.

In order to improve this, an attempt has been made to form the phase change pattern in a contact hole having a narrow space. For example, a phase change pattern made of the GST film is formed in a confined structure such as a contact hole. In this case, a process of physical vapor deposition such as sputtering is used to deposit the GST film in the contact hole. However, by using the physical vapor deposition process, not only the GST film does not have a dense structure, but also the grain size of the GST film may be too large. Thus, in filling the phase change pattern in the localized structure, voids or seams may be generated in the phase change pattern. The voids and / or shims degrade the characteristics of the phase change pattern. For example, the void and / or shim formed part of the phase change pattern may have a very high resistance. Accordingly, even if the phase change pattern is converted into a crystalline state or an amorphous state, the resistance change of the phase change pattern may be insensitive. In other words, the difference in resistance between the reset state and the set state can be reduced due to the voids and / or shims. As a result, the sensing margin of the phase change memory device can be reduced. Also, due to the voids and / or shims, uniformity of resistances of the reset state (or the set state) of the unit cells in the phase change memory device may be reduced, resulting in malfunction of the phase change memory device.

SUMMARY OF THE INVENTION The present invention has been made in an effort to provide a method for manufacturing a phase change memory device, which contributes to improving the reliability of a semiconductor device by forming a phase change material film having small grains.

According to one aspect of the present invention for achieving the above technical problem, a method of manufacturing a phase change memory element is provided. The method of manufacturing the phase change memory device includes at least one source gas from a group consisting of source gases each containing elements of a phase change material film containing germanium (Ge), tellurium (Te), and antimony (Sb). Supplying and depositing a first material film on the substrate. The dopant is plasma-doped with the first material layer.

In some embodiments of the present invention, the first material film may be formed using plasma enhanced cyclic PECVD or plasma enhanced atomic layer deposition (PEALD).

In other embodiments, the impurity may contain oxygen, nitrogen or carbon.

In still other embodiments, the first source gas containing germanium, the second source gas containing tellurium and the third source gas containing antimony may be MeGe (NEtMe) _3, Te (t−) _, respectively. Bu) ₂ and Sb (i-Pr) ₃ .

In still other embodiments, the deposition of the first material layer and the doping of the impurities may be performed in-situ.

In still other embodiments, the method may further include forming an interlayer insulating film having an opening on the substrate before depositing the first material film on the substrate, wherein the first material film may be formed to fill the opening. .

In still other embodiments, the formation of the first material layer and the doping of the impurities may be repeatedly performed at least once.

In still other embodiments, when the first material film is formed by supplying a first source gas, after the doping of the impurity, a second material film is supplied onto the doped first material film by supplying a second source gas. Can be formed. The impurity may be plasma-doped to the second material layer. The third material layer may be formed by supplying a third source gas on the doped second material layer. The impurity may be plasma doped into the third material layer.

In still other embodiments, when the first material film is formed by supplying first and second source gases, after the doping of the impurity, the second and third source gases are supplied to supply the doped first material. A fourth material film may be formed on the film. The impurity may be plasma doped into the fourth material layer. In this case, before depositing the first material film on the substrate, a lower electrode may be formed on the substrate. After the doping of the impurity, a combination material layer stacked with the material layers may be patterned to form a phase change material pattern. An upper electrode may be formed on the phase change pattern.

According to the present invention, by using cyclic PECVD or PEALD to form a material film containing germanium, tellurium and antimony, respectively, and after forming the material film of each element, the phase change material film by plasma doping the material film with impurities It is formed to have a small grain size. Accordingly, the phase change material film in a confined structure such as a contact hole may be formed without voids and / or seams. As a result, the resistance values between the phase change patterns of the reset state and the phase change patterns of the set state not only have a large difference, but also the phase change patterns of the unit cells in the phase change memory device have a uniform reset state (or the Set resistances).

In addition, the impurity doped phase change material film may be formed to have a greater resistance than the undoped phase change material film. As a result, the amount of current for converting the phase change material film into the reset or set state is reduced, so that the phase change memory device can be operated at low power. In conclusion, it is possible to secure the reliability of the phase change memory device.

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 scope of the invention to those skilled in the art will fully convey. In the drawings, the thicknesses of layers and regions are exaggerated for clarity. Like numbers refer to like elements throughout. Also, an element or layer is referred to as "on" or "on" of another element or layer by interposing another layer or other element in the middle as well as directly above the other element or layer. Include all cases.

2 to 8B, a method of manufacturing a phase change memory device according to an embodiment of the present invention will be described. 2 is a plan view illustrating a portion of a cell array region of a phase change memory device according to an embodiment of the present invention, and FIGS. 3 to 7 illustrate a method of manufacturing a phase change memory device according to an embodiment of the present invention. 2 are cross-sectional views taken along the line II ′ of FIG. 2. 8A and 8B illustrate process flows illustrating a process of forming a phase change material film in a method of manufacturing a phase change memory device according to example embodiments.

2 and 3, an isolation layer 112 may be formed on the substrate 110 to define word lines 114 and WL. The substrate 110 may be formed of a semiconductor substrate such as a silicon wafer. The device isolation film 112 may be formed using a trench device isolation technology. The device isolation film 112 may be formed of an insulating film such as a silicon oxide film, a silicon nitride film, a silicon oxynitride film, or a combination thereof. The word lines 114 and WL may be formed as high concentration impurity ion implantation regions. For example, the word line 114 may be doped with n-type impurities. In another embodiment, the word line WL may be formed of conductive wires stacked on the substrate 110. The conductive wiring may be formed of a metal wiring or an epitaxial semiconductor pattern.

An insulating layer 120 may be formed on the word line 114 and the device isolation layer 112. The insulating film 120 may be formed of an insulating film such as a silicon oxide film, a silicon nitride film, a silicon oxynitride film, or a combination thereof. A diode D may be formed in the insulating layer 120. The diode D may be formed by sequentially stacking a first semiconductor pattern 124 and a second semiconductor pattern 126 on a predetermined region of the word line 114.

The first semiconductor pattern 124 may be formed of an n-type or p-type semiconductor film. The second semiconductor pattern 126 may be formed of a conductive semiconductor layer different from the first semiconductor pattern 124. For example, the first semiconductor pattern 124 may be formed of an n-type semiconductor film, and the second semiconductor pattern 126 may be formed of a p-type semiconductor film.

The diode electrode 128 may be formed on the second semiconductor pattern 126. The diode electrode 128 may be formed of a conductive film such as a metal film or a metal silicide film. The upper surfaces of the insulating layer 120 and the diode electrode 128 may be planarized. In this case, the upper surface of the diode electrode 128 may be exposed.

A lower interlayer insulating layer 130 may be formed to cover the insulating layer 120. The lower interlayer insulating film 130 may be formed of an insulating film such as a silicon oxide film, a silicon nitride film, a silicon oxynitride film, or a combination thereof. An opening 132 may be formed through the lower interlayer insulating layer 130 to expose the diode electrode 128.

Subsequently, a lower electrode 134 may be formed on the diode electrode 128 in the opening 132. The lower electrode 134 may be formed of a ternary layer including a transition metal film, a transition metal nitride film, and a transition metal. For example, the lower electrode 134 includes one selected from the group consisting of a titanium film, a titanium nitride film, a titanium aluminum nitride film, a tungsten film, a tungsten nitride film, a tantalum film, a tantalum nitride film, a tantalum carbon nitride film, and a tungsten carbon nitride film. It can be formed to. The lower electrode 134 may be formed by forming a conductive film filling the opening 132 and etching back the conductive film. Although not shown in the present embodiment, an insulating spacer may be formed on sidewalls of the opening 132. This is to reduce the phase change pattern formed afterwards and the contact area with the lower electrode 134.

2 and 4, a first material layer 136 may be deposited on the lower electrode 134 in the opening 132. In the present embodiment, the first material film 136 is formed as a germanium film will be described as an example. The germanium layer 136 may be formed of a plasma enhanced chemical vapor deposition (hereinafter referred to as cyclic PECVD) or plasma enhanced atomic layer deposition (hereinafter referred to as PEALD). It can be formed using. In this case, the first source gas containing germanium is MeGe (NEtMe) ₃ , Ge (iPro) ₃ H, Ge (Me) ₄ , Ge (Me) ₄ N ₃ , Ge (Et) ₄ , Ge ( Et) ₄ , Sb (GeMe ₃ ) ₃ , Ge (nBu) _4, and Sb (GeEt ₃ ) ₃ and at least one selected from the group consisting of. Specifically, as shown in FIG. 8A, the substrate 110 having the opening 132 is loaded into a chamber (not shown) of the apparatus for performing the processes, and the first source into the chamber for t1 time. Supply gas. At the same time, plasma may be supplied to the chamber to convert the first source gas into plasma, thereby contributing to the formation of the germanium layer 136.

After the germanium layer 136 is formed to have a predetermined thickness, the supply of the first source gas is stopped and a purge gas such as argon gas or nitrogen gas is supplied to the chamber to supply the first source gas. Can be purged.

2 and 5, an impurity 30 may be implanted into the germanium layer 136. Specifically, as shown in FIG. 8B, the plasma containing the impurity 30 may be supplied to the chamber, and the gas containing the impurity 30 may be supplied for a time t2 shorter than the time t1. In this case, the formation of the germanium film 136 and the doping of the impurity 30 may proceed in-situ.

In this case, the impurity 30 may contain oxygen, nitrogen or carbon. Accordingly, the gases containing the impurity 30 may be O ₂ , NH ₃ or C ₂ H ₄ , respectively. In addition, when the impurity 30 is carbon, carbon among the components of the first source gas remaining in the chamber may be plasma doped into the germanium layer 136. At this time, H2 gas or He gas may be supplied to the chamber as a reaction gas.

As a result, the germanium film 138 doped with the impurity 30 may be formed by the aforementioned plasma doping. As a result, the resistance of the doped germanium layer 138 may be increased.

Thereafter, the gas containing the impurity 30 may be purged using argon gas or nitrogen gas.

Referring to FIGS. 2 and 6, the second material film may be formed on the doped germanium film 138 by supplying a second source gas to the chamber for t3 time as in the process flow shown in FIG. 8A. . At the same time, the second source gas may be plasma-supplied by plasma supply to the chamber to contribute to the formation of the second material film. That is, the second material film may be formed using cyclic PECVD or PEALD. In the present embodiment, the second material film is exemplified as being formed of a tellurium film. In this case, the second source gas containing tellurium is Te (t-Bu) ₂ , Te (Me) ₂ , Te (Et) ₂ , Te (n-Pr) ₂ and Te (i-Pr) It may include at least one selected from the group consisting of _two .

After the tellurium film is formed to have a predetermined thickness, the supply of the second source gas is stopped, and a purge gas such as argon gas or nitrogen gas is supplied to the chamber to purge the second source gas. Can be.

Subsequently, an impurity may be plasma-doped with the tellurium film to form a telerium film 140 doped with the impurity. The plasma doping of the impurity may be performed for a t4 time shorter than t3, as shown in FIG. 8A. Since the impurity gas type and the doping process are substantially the same as the method described with reference to FIG. 5, a description thereof will be omitted.

Subsequently, a third source gas is supplied to the chamber for t5 hours as shown in FIG. 8A on the doped telerium film 140, and then the third source gas is formed on the doped telluridium film 140. A material film can be formed. At the same time, plasma may be provided to the chamber to plasma the third source gas, thereby contributing to the formation of the third material layer. That is, the third material film may be formed using cyclic PECVD or PEALD. In the present embodiment, the third material film is exemplified as an antimony film. In this case, the third source gas containing the antimony is Sb (i-Pr) ₃ , Sb (i-bu) ₃ , Sb (Me) ₃ , Sb (Et) ₃ , Sb (n-Pr) ₃ , Sb (t-Bu) ₃ and Sb [N (Me) ₂ ] ₃ .

Subsequently, the antimony film may be plasma-doped with impurities to form an antimony film 142 doped with the impurities. The plasma doping of the impurity may be performed for a time t6 shorter than t5, as shown in FIG. 8A. Since the impurity gas type and the doping process are substantially the same as the method described with reference to FIG. 5, a description thereof will be omitted.

As a result, a phase change material film including a doped germanium film 138, the doped tellurium film 140, and the doped antimony film 142 may be formed by filling the opening 132. do. The phase change material layer may have a higher resistance than the undoped GST layer by including the GST layer doped with the impurity.

In the present exemplary embodiment, the doped germanium layer 138, the doped tellurium layer 140, and the doped antimony layer 142 fill the opening 132 by one deposition. However, the present invention is not limited thereto, and the doped layers 138, 140, and 142 may be repeatedly formed to fill the openings 132.

In addition, in another embodiment, as shown in the process flow of FIG. 8B, the first and second source gases may be mixed and supplied to the chamber of the cyclic PECVD or PEALD apparatus for t1 hour. In this case, plasma can be supplied to the chamber. For example, the first and second source gases may be gases containing the germanium and the tellurium, respectively. The first and second source gases may be the listed source gases described with reference to FIGS. 4 and 6. As a result, a binary alloy film of the germanium and the tellurium may be formed, and a first alloy material film may be formed on the lower electrode 134 of the opening 132. Thereafter, the first and second source gases may be purged from the chamber to the outside.

Next, as shown in FIG. 8B, the plasma containing the impurity may be supplied to the chamber, and the gas containing the impurity may be supplied for a t2 time shorter than the t1 time. In this case, the formation of the first alloy material layer and the doping of the impurities may be performed in-situ. As a result, the first alloy material layer doped with the impurity may be formed by implanting the impurity into the first alloy material layer by the plasma doping. In this case, the impurities may contain oxygen, nitrogen or carbon. Accordingly, the gases containing the impurity may be O 2, NH 3 or C 2 H 4, respectively. Thereafter, the gas containing the impurity may be purged using argon gas or nitrogen gas.

Subsequently, the second source gas and the third source gas may be mixed and supplied to the chamber for t3 hours. Even in this case, plasma can be supplied to the chamber. For example, the second and third source gases may be gases containing the tellurium and the antimony, respectively. In this case, the second and third source gases may be the listed source gases described with reference to FIG. 6. As a result, a binary alloy film of the tellurium and the antimony may be formed, and a second alloy material film may be formed on the first alloy material film.

Subsequently, as shown in FIG. 8B, the plasma containing the impurity may be supplied to the chamber, and the gas containing the impurity may be supplied for a t4 time shorter than the t3 time. As a result, the second alloy material layer doped with the impurity may be formed by implanting the impurity into the second alloy material layer by the above-described plasma doping. Since the impurity gas type and the doping process are substantially the same as the doping method for the first alloy material layer, description thereof will be omitted.

In this embodiment, the doped first alloy material film and the doped second alloy material film may each fill the opening by one deposition, or the doped films may be repeatedly formed to fill the opening.

2 and 7, the phase change pattern 144 may be formed by planarizing the phase change material layer protruding from the opening 132 so that the upper surface of the lower interlayer insulating layer 130 is exposed. The planarization can be carried out using chemical mechanical polishing (CMP).

Subsequently, an upper interlayer insulating layer 146 may be formed to cover the lower interlayer insulating layer 130. The upper interlayer insulating film 146 may be formed of an insulating film such as a silicon oxide film, a silicon nitride film, a silicon oxynitride film, or a combination thereof.

An upper electrode 148 may be formed on the phase change pattern 144 in the upper interlayer insulating layer 146. The upper electrode 148 may be formed to cover the opening 132. Bit lines 150 and BL may be formed on the upper interlayer insulating layer 146 to cross the upper electrode 148. The upper electrode 148 may be formed to include one selected from the group consisting of a titanium film, a titanium nitride film, a titanium aluminum nitride film, a tungsten film, a tungsten nitride film, a tantalum film, a tantalum nitride film, a tantalum carbon nitride film, and a tungsten carbon nitride film. . The bit line 150 may be formed of a conductive film such as a metal film, a polysilicon film, a metal silicide film, or a combination thereof.

Experimental Examples

9A and 9B illustrate a morphology of a conventional phase change material film surface and a surface of the phase change material film prepared according to an embodiment of the present invention. 9A and 9B, the germanium-containing first source gas, the tellurium-containing second source gas, and the antimony-containing third source gas may be MeGe (NEtMe). _3, Te (t-Bu) ₂ and Sb (i-Pr) ₃ were used. The phase change material layers were formed on the interlayer insulating layer having an opening on the silicon substrate by supplying the source gases.

Specifically, the phase change material film of FIG. 9A was formed using CVD, and the CVD process was performed at a temperature of 350 ° C. Meanwhile, the phase change material film of FIG. 9B was formed of a Ge ₂₇ Sb ₁₃ Te ₅₉ film doped with oxygen, and formed using PEALD. According to the process of manufacturing a phase change material film according to the present invention, the germanium film, the tellurium film, the antimony film, and the tellurium film were sequentially formed according to the process flow shown in FIG. 8A. In this case, the PEALD process was carried out at a temperature of 200 ° C. In addition, the doping of the impurity is conducted using an O ₂ gas, the O ₂ gas was supplied to the chamber at a flow rate of 100sccm. In addition, the source power supplied to the chamber was provided at 50W and the pressure in the chamber was provided at 1torr. The O ₂ gas was supplied at 3 seconds, 2 seconds, 2 seconds and 2 seconds respectively after formation of the listed films.

The conventional phase change material film shown in FIG. 9A has a large grain size and exhibits poor morphology. On the other hand, the phase change material film produced by the present invention shown in FIG. 9B has a smaller grain size than the conventional one and exhibits good morphology. For this reason, the phase change material film produced by the present invention can be formed well in the localized structure such as the opening. That is, the phase change material film has excellent gap fill characteristics. 10 is a cross-sectional view of a phase change material film manufactured according to an embodiment of the present invention. As shown in FIG. 10, the phase change material layer 144a may be formed in the opening without voids and / or seams.

FIG. 11A is a graph showing an X-ray diffraction pattern (XRD) of a conventional phase change material film, and FIG. 11B shows an X-ray diffraction pattern of a phase change material film prepared according to an embodiment of the present invention. One graph. In FIGS. 11A and 11B, the abscissa is the angle (2θ) between the X-ray light source and the detector centered on the specimen (substrate with the phase change material film described with reference to FIGS. 9A and 9B) in the X-ray diffractometer, The vertical axis represents intensity of light diffracted by the phase change material film, that is, intensity.

In FIG. 11A, a conventional phase change material film has a hexagonal closed-packed lattice (HCP) structure. In contrast, in FIG. 11B, the phase change material film produced by the method of the present invention exhibits a face centered cubic lattice (FCC) structure. Accordingly, the phase change material film according to the present invention may have better electrical characteristics than the conventional phase change material film.

1 is a partial cross-sectional view schematically showing a conventional phase change memory cell.

2 is a plan view illustrating a portion of a cell array region of a phase change memory device according to an embodiment of the present invention.

3 to 7 are cross-sectional views taken along the line II ′ of FIG. 2 to explain a method of manufacturing a phase change memory device according to an embodiment of the present invention.

8A and 8B are process flows illustrating a process of forming a phase change material film in a method of manufacturing a phase change memory device according to embodiments of the present invention.

9A and 9B are diagrams illustrating morphologies of a conventional phase change material film surface and a phase change material film surface manufactured according to an embodiment of the present invention, respectively.

10 is a cross-sectional view of a phase change material film manufactured according to an embodiment of the present invention.

11A and 11B are graphs showing X-ray diffraction patterns of a conventional phase change material film and a phase change material film prepared according to an embodiment of the present invention, respectively.

Claims (10)

The first material film is supplied onto the substrate by supplying at least one source gas from a group consisting of source gases each containing elements of the phase change material film containing germanium (Ge), tellurium (Te), and antimony (Sb). Deposited on, And plasma doping impurities into the first material layer. The method of claim 1, And the first material film is formed using plasma enhanced cyclic PECVD or plasma enhanced atomic layer deposition (PEALD). The method of claim 1, And the impurity contains oxygen, nitrogen, or carbon. The method of claim 1, The first source gas containing germanium, the second source gas containing tellurium and the third source gas containing antimony are MeGe (NEtMe) _3, Te (t-Bu) ₂ and Sb (i -Pr) A method for manufacturing a phase change memory device formed of ₃ . The method of claim 1, The method of claim 1, wherein the deposition of the first material layer and the doping of the impurities are performed in-situ. The method of claim 1, And forming an interlayer insulating film having an opening on the substrate before depositing the first material film on the substrate, wherein the first material film is formed to fill the opening. The method of claim 1, The method of claim 1, wherein the formation of the first material layer and the doping of the impurities are repeatedly performed at least once. The method of claim 1, When the first material film is formed by supplying a first source gas, after doping the impurity, a second source gas is supplied to form a second material film on the doped first material film, Plasma doping the impurity into the second material layer, Supplying a third source gas on the doped second material layer to form a third material layer, And plasma doping the impurity into the third material layer. The method of claim 1, When the first material film is formed by supplying first and second source gases, after the doping of the impurity, the second material film is supplied onto the doped first material film by supplying the second and third source gases. Forming, And plasma doping the impurity into the fourth material layer. The method according to any one of claims 8 and 9, Before depositing the first material film on the substrate, forming a lower electrode on the substrate, After the doping of the impurity, a combination material film stacked with the material films is patterned to form a phase change material pattern, And forming an upper electrode on the phase change pattern.

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