CN110571329A - High-reliability phase-change material, phase-change memory and preparation method - Google Patents
High-reliability phase-change material, phase-change memory and preparation method Download PDFInfo
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- 239000012782 phase change material Substances 0.000 title claims abstract description 155
- 238000002360 preparation method Methods 0.000 title claims description 20
- 230000008859 change Effects 0.000 claims abstract description 53
- 238000000034 method Methods 0.000 claims abstract description 26
- 229910017629 Sb2Te3 Inorganic materials 0.000 claims abstract description 15
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- 238000001755 magnetron sputter deposition Methods 0.000 claims description 9
- 238000004519 manufacturing process Methods 0.000 claims description 9
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- 238000001259 photo etching Methods 0.000 claims description 2
- 238000000233 ultraviolet lithography Methods 0.000 claims description 2
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N70/00—Solid-state devices having no potential barriers, and specially adapted for rectifying, amplifying, oscillating or switching
- H10N70/011—Manufacture or treatment of multistable switching devices
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- H10N70/00—Solid-state devices having no potential barriers, and specially adapted for rectifying, amplifying, oscillating or switching
- H10N70/011—Manufacture or treatment of multistable switching devices
- H10N70/021—Formation of switching materials, e.g. deposition of layers
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- H10N70/00—Solid-state devices having no potential barriers, and specially adapted for rectifying, amplifying, oscillating or switching
- H10N70/011—Manufacture or treatment of multistable switching devices
- H10N70/061—Shaping switching materials
- H10N70/066—Shaping switching materials by filling of openings, e.g. damascene method
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- H10N70/00—Solid-state devices having no potential barriers, and specially adapted for rectifying, amplifying, oscillating or switching
- H10N70/801—Constructional details of multistable switching devices
- H10N70/821—Device geometry
- H10N70/826—Device geometry adapted for essentially vertical current flow, e.g. sandwich or pillar type devices
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- H10N70/00—Solid-state devices having no potential barriers, and specially adapted for rectifying, amplifying, oscillating or switching
- H10N70/801—Constructional details of multistable switching devices
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- H10N70/00—Solid-state devices having no potential barriers, and specially adapted for rectifying, amplifying, oscillating or switching
- H10N70/801—Constructional details of multistable switching devices
- H10N70/881—Switching materials
- H10N70/882—Compounds of sulfur, selenium or tellurium, e.g. chalcogenides
- H10N70/8828—Tellurides, e.g. GeSbTe
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Abstract
The invention discloses a high-reliability phase change material which is a superlattice-like phase change material layer formed by circularly and alternately laminating a first phase change material layer and a second phase change material layer, wherein a superlattice-like interface is formed between the first phase change material layer and the second phase change material layer, and the first phase change material layer is Sb2Te3As an inducing layer, the second phase change material layer is Ge15Te85The number of the circularly alternating laminated layers is at least three. Amorphous Sb2Te3The energy required for crystallization of the layer is low and stable lattice orientation is easy to form, so the Sb2Te3 layer can be selected as an inducing layer to induce Ge in amorphous state15Te85The layer has higher phase change speed in the phase change process, and can promote the whole phase change material to be rapidly crystallized; and selected Ge15Te85in the band structure of the layer, the defect state is mainly localized at the tail of the band, but not at the defect level near the Fermi level in the band gap, and the resistance drift due to the relaxation of the defect level does not occurThis has a higher phase change speed during the phase change.
Description
Technical Field
the invention belongs to the field of microelectronics, and particularly relates to a high-reliability phase-change material and a preparation method thereof, and a phase-change memory adopting the high-reliability phase-change material and a preparation method thereof.
background
As a novel memory, the phase change memory perfectly fills up the device fault in the existing memory framework due to proper storage density, erasing speed and power consumption. Moreover, since the phase change memory is highly compatible with the existing CMOS, it is one of the best solutions for the next generation memory architecture, and has great commercial potential in high density, high speed, low power consumption, embedded applications and special environment applications.
The phase change memory adopts a phase change material as a storage medium, joule heat generated by electric pulses is that the resistance state of the phase change material changes, and the resistance value of the phase change material is high resistivity in an amorphous state and low resistivity in a crystalline state generally, so that different resistance values can be obtained by combining the size of a device. Since the phase change material can be partially amorphized, the phase change memory has great advantages in the application of multi-value storage. However, the phase change material has intrinsic resistance drift in an amorphous state, and different resistance states overlap when multi-value storage is performed, thereby causing misreading with high probability.
The following methods are commonly used to reduce the resistance drift of the phase change memory:
firstly, the spontaneous relaxation of the phase-change material is accelerated by low-temperature annealing or other aging accelerating methods, so that the material enters a relatively stable state as soon as possible, and the resistance drift generated in use is reduced.
And the other is to change the read-write mode of the unit, for example, the resistance weight is converted into physical quantities such as voltage or current to represent the stored information.
And thirdly, improving the structure of the device, such as adding a metallized covering layer to inhibit resistance drift.
however, since the resistance drift of a phase change material is determined by the intrinsic properties of the material, regardless of the size of the material and the device on a spatial scale exceeding 10nm, optimization of the device structure cannot substantially reduce the resistance drift of the phase change memory. The improvement of the read-write mode increases the cost of the design of the peripheral circuit on one hand and reduces the read-write speed on the other hand.
Therefore, a novel phase change material with low drift and compatible performance is one of the problems to be solved in the current field.
disclosure of Invention
Aiming at least one of the defects or the improvement requirements in the prior art, particularly how to reduce resistance drift, improve reliability and simultaneously consider the performances of phase change speed and the like, the invention provides a high-reliability phase change material and a phase change memory, wherein a phase change material layer Sb is adopted2Te3And a phase change material layer Ge15Te85Forming a high-reliability quasi-superlattice phase-change material layer by cyclic alternating superposition, wherein the amorphous Sb2Te3The energy required for crystallization of the layer is low and stable lattice orientation is easy to form, so the Sb2Te3 layer can be selected as an inducing layer to induce Ge in amorphous state15Te85the layer has higher phase change speed in the phase change process, and can promote the whole phase change material to be rapidly crystallized; and selected Ge15Te85in the energy band structure of the layer, the defect state is mainly located in a local state of a band tail, but the defect level near the Fermi level in the band gap is not subjected to resistance drift due to relaxation of the defect level, so that the layer has higher phase change speed in the phase change process.
In order to achieve the above object, according to one aspect of the present invention, there is provided a high-reliability phase change material, which is a superlattice-like phase change material layer formed by cyclically and alternately laminating a first phase change material layer and a second phase change material layer, wherein a superlattice-like interface is formed between the first phase change material layer and the second phase change material layer, and the first phase change material layer is Sb2Te3as an inducing layer, the second phase change material layer is Ge15Te85The number of the circularly alternating laminated layers is at least three, and the bottom layer and the top layer are both selected from one of the first phase change material layer and the second phase change material layer.
in order to achieve the above object, according to another aspect of the present invention, there is also provided a method for preparing the phase change material with high reliability as described above, wherein:
the preparation method comprises the step of depositing the first phase change material layer and the second phase change material layer alternately in a circulating mode through a deposition method comprising magnetron sputtering, electron beam evaporation, atomic layer deposition and chemical reaction deposition until the preparation of the superlattice-like phase change material layer is completed.
To achieve the above object, according to another aspect of the present invention, there is provided a phase change memory, including:
A layer of substrate material;
A first electrode;
the insulating medium material layer is provided with a contact hole;
The superlattice phase change material layer is formed by circularly and alternately laminating a first phase change material layer and a second phase change material layer, a superlattice interface is formed between the first phase change material layer and the second phase change material layer, and the first phase change material layer is Sb2Te3as an inducing layer, the second phase change material layer is Ge15Te85The number of the layers is at least three, and the bottom layer and the top layer are both selected from one of the first phase change material layer and the second phase change material layer;
A second electrode;
The superlattice phase change material layer-like part is positioned in the contact hole of the insulating medium material layer and is in contact with the first electrode.
Preferably, the contact area of the superlattice phase change material layer and the first electrode is smaller than the contact area of the second electrode and the superlattice phase change material layer.
Preferably, the bottom layers of the superlattice phase change material layer are of a structure with grooves, and the top layer and the second electrode are planar layers.
In order to achieve the above object, according to another aspect of the present invention, there is also provided a method for manufacturing a phase change memory as described above, including the steps of:
S1: depositing a first electrode on the layer of substrate material;
s2: depositing a layer of insulating dielectric material over the first electrode;
S3: preparing a contact hole;
Forming a contact hole with a preset size on the local surface of the insulating medium material layer by using photoetching;
s4: preparing a superlattice-like phase change material layer;
Forming an electrode pattern by using a first electrode in an etching alignment contact hole, and then circularly and alternately depositing a first phase change material layer and a second phase change material layer in the contact hole and on the periphery by a deposition method until the preparation of the superlattice-like phase change material layer is completed;
S5: preparing a second electrode;
and after the preparation of the superlattice phase change material-like layer is completed, directly depositing a second electrode on the superlattice phase change material-like layer.
Preferably, in steps S1, S2, S4 and S5, the deposition method employs any one of magnetron sputtering, electron beam evaporation, atomic layer deposition and chemical reaction deposition.
preferably, in step S2, the thickness of the insulating medium material layer is adjusted according to the thickness of the superlattice phase change material-like layer, and the thicker the design thickness of the superlattice phase change material-like layer prepared later, the thicker the thickness of the insulating medium material layer deposited earlier.
Preferably, in step S3, the photolithography method employs ultraviolet lithography or electron beam lithography.
Preferably, in step S4, the etching method uses reactive ion etching or coupled plasma etching.
The above-described preferred features may be combined with each other as long as they do not conflict with each other.
generally, compared with the prior art, the above technical solution conceived by the present invention has the following beneficial effects:
1. The invention relates to a high-reliability phase-change material, a phase-change memory and a preparation method thereof2Te3and a phase change material layer Ge15Te85forming a high-reliability quasi-superlattice phase-change material layer by cyclic alternating superposition, wherein the amorphous Sb2Te3the energy required for crystallization of the layer is low and stable lattice orientation is easy to form, so the Sb2Te3 layer can be selected as an inducing layer to induce Ge in amorphous state15Te85The layer has higher phase change speed in the phase change process, and can promote the whole processCarrying out rapid crystallization on the phase-change material; and selected Ge15Te85in the energy band structure of the layer, the defect state is mainly located in a local state of a band tail, but the defect level near the Fermi level in the band gap is not subjected to resistance drift due to relaxation of the defect level, so that the layer has higher phase change speed in the phase change process.
2. According to the high-reliability phase change material, the phase change memory and the preparation method, due to the existence of the superlattice-like interface between the first phase change material layer and the second phase change material layer, the resistance drift is far lower than that of the traditional phase change material, the reliability of the device can be greatly improved on the premise of not changing the structure of the device and not consuming extra circuits, and the development requirement of the device with a small size can be met.
Drawings
FIG. 1 is a schematic cross-sectional view of a phase change memory using a high reliability phase change material according to an embodiment of the present invention;
FIG. 2 is a flow chart of a process for fabricating a phase change memory using a high reliability phase change material according to an embodiment of the present invention;
FIG. 3 is a second flowchart illustrating a process for fabricating a phase change memory using a high reliability phase change material according to an embodiment of the present invention;
FIG. 4 is a third flowchart of a phase change memory fabrication process using a high reliability phase change material according to an embodiment of the present invention;
FIG. 5 is a fourth flowchart illustrating a process for fabricating a phase change memory using a high reliability phase change material according to an embodiment of the present invention;
Fig. 6 is a flow chart of a process for manufacturing a phase change memory using a high-reliability phase change material according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other. The present invention will be described in further detail with reference to specific embodiments.
As shown in fig. 1, the present invention provides a high-reliability phase change material, which is a superlattice-like phase change material layer 106 formed by cyclically and alternately laminating a first phase change material layer 104 and a second phase change material layer 105, wherein a superlattice-like interface is formed between the first phase change material layer 104 and the second phase change material layer 105.
The first phase change material layer 104 is Sb2Te3As an inducing layer, it is used to promote the rapid crystallization of the entire superlattice phase-change material layer 106.
The second phase change material layer 105 is Ge15Te85and the phase change speed is higher in the phase change process. Because the defect state in the energy band structure of the material is mainly located in the local state of the band tail, but not in the defect energy level near the Fermi level in the band gap, the resistance drift can not occur due to the relaxation of the defect energy level.
in the present invention, the number of the cyclically alternating layers is at least three, and the bottom layer (starting layer) and the top layer (ending layer) are not limited to which material is shown in fig. 1 to 6, and may be selected from one of the first phase change material layer 104 and the second phase change material layer 105.
as shown in fig. 5, the present invention further provides a method for preparing the phase change material with high reliability, wherein:
the preparation method comprises the step of depositing the first phase-change material layer 104 and the second phase-change material layer 105 alternately in a circulating mode through a deposition method comprising magnetron sputtering, electron beam evaporation, atomic layer deposition and chemical reaction deposition until the preparation of the superlattice-like phase-change material layer 106 is completed.
As shown in fig. 1, the present invention further provides a phase change memory, which includes:
A substrate material layer 100, the whole memory cell is prepared on the substrate material layer 100 which takes silicon or doped silicon as a main body and has an insulating material on the surface;
a first electrode (bottom electrode) 101, wherein the first electrode 101 extends over the entire surface of the substrate material layer 100 and contacts the bottom surface of the superlattice-like phase change material layer 106;
An insulating medium material layer 103 for forming a confinement structure for the superlattice-like phase change material layer 106, wherein a contact hole 110 is formed in the insulating medium material layer 103;
A quasi-superlattice phase-change material layer 106 formed by circularly and alternately laminating a first phase-change material layer 104 and a second phase-change material layer 105, wherein a quasi-superlattice interface is formed between the first phase-change material layer 104 and the second phase-change material layer 105, and the first phase-change material layer 104 is Sb2Te3as an inducing layer, the second phase change material layer 105 is Ge15Te85the number of the layers is at least three, and the bottom layer and the top layer are both selected from one of the first phase change material layer 104 and the second phase change material layer 105;
A second electrode (top electrode) 102, the second electrode 102 contacting the upper surface of the superlattice-like phase-change material layer 106;
The superlattice phase-change material layer 106 is partially positioned in the contact hole 110 of the insulating medium material layer and is in contact with the first electrode 101.
as shown in fig. 1, the insulating dielectric material layer 103 is formed with a relatively narrow width (which may be a diameter in some embodiments) by etching or the like, and may form an electrode surface area in contact with the superlattice-like phase change material layer 106. The contact area of the superlattice phase-change material layer 106 and the first electrode 101 is smaller than the contact area of the second electrode 102 and the superlattice phase-change material layer 106. Therefore, the current is concentrated on the portion of the superlattice phase change material layer 106 in contact with the first electrode 101.
as shown in fig. 1, the bottom layers of the superlattice phase-change material layer 106 are recessed structures, and the top layer thereof and the second electrode 102 are planar layers.
As shown in fig. 2 to 6, the method for manufacturing a phase change memory of the present invention includes the following steps:
S1: a first electrode 101 is deposited on the layer of substrate material 100.
As shown in fig. 2, the first electrode 101 may be deposited by magnetron sputtering, electron beam evaporation, atomic layer deposition, chemical reaction deposition, or the like. The first electrode 101 includes, but is not limited to, an inert noble metal having a large work function, such as Pt, Au, etc., an inert metal having a high heat generation coefficient, such as tungsten (W), titanium tungsten alloy (TiW), etc., a metal or alloy compatible with the current microelectronics technologies, such as metal nitride MN (M ═ Ti, Ta …), copper (Cu), aluminum (Al), etc. The thickness of the first electrode is adjusted according to the subsequent integration process, and in the present embodiment, the thickness of the first electrode is preferably 100 nm.
S2: a layer of insulating dielectric material 103 is deposited over the first electrode 101.
As shown in fig. 3, the insulating dielectric material layer 103 may be deposited by magnetron sputtering, electron beam evaporation, atomic layer deposition, chemical reaction deposition, or the like. The insulating dielectric material layer 103 includes, but is not limited to, materials suitable for the inner dielectric structure of the memory element, such as silicon oxide (SiO), silicon nitride (SiN), silicon oxynitride (SiON), silicon carbide (SiC), aluminum oxide (AlO), hafnium oxide (HfO), or other materials suitable for the inner dielectric structure of the memory element. The thickness of the insulating medium material layer 103 is adjusted according to the thickness of the superlattice phase change material layer 106, and the thicker the design thickness of the later prepared superlattice phase change material layer 106 is, the thicker the thickness of the insulating medium material layer 103 deposited earlier is. In the present embodiment, the insulating dielectric material layer 103 is preferably 100nm thick silicon dioxide (SiO 2).
S3: contact holes 110 are prepared.
as shown in fig. 4, contact holes 110 of a predetermined size are formed on a partial surface of the insulating dielectric material layer 103 using uv lithography or electron beam lithography.
S4: a superlattice-like phase change material layer 106 is prepared.
as shown in fig. 5, an electrode pattern is formed by aligning the first electrode 101 in the contact hole 110 using Reactive Ion Etching (RIE) or coupled plasma etching (ICP), and then the first phase change material layer 104 and the second phase change material layer 105 are cyclically and alternately deposited in a deposition method in and around the contact hole until the preparation of the superlattice-like phase change material layer 106 is completed; the deposition method adopts any one of magnetron sputtering, electron beam evaporation, atomic layer deposition and chemical reaction deposition.
Wherein, the bottom several layers of the superlattice-like phase change material layer 106 are structures with grooves, and the top layer thereof, such as the first phase change material layer 104, becomes a planar layer.
And the second electrode 102 is a planar layer.
S5: a second electrode 102 is prepared.
As shown in fig. 6, after the preparation of the superlattice phase-change material layer 106 is completed, the photolithography pattern is retained, and the second electrode 102 is directly deposited on the top planar layer of the superlattice phase-change material layer 106 to form a planar second electrode. The deposition method adopts any one of magnetron sputtering, electron beam evaporation, atomic layer deposition and chemical reaction deposition. The second electrode 102 includes, but is not limited to, an inert noble metal having a large work function, such as Pt, Au, etc., an inert metal having a high heat generation coefficient, such as tungsten (W), titanium tungsten alloy (TiW), etc., a metal or alloy compatible with the current microelectronics technologies, such as metal nitride MN (M ═ Ti, Ta …), copper (Cu), aluminum (Al), etc. The thickness of the second electrode is adjusted according to the subsequent integration process, and in the present embodiment, the thickness of the second electrode is preferably 100 nm.
In summary, the present invention has the following advantages:
1. The invention relates to a high-reliability phase-change material, a phase-change memory and a preparation method thereof2Te3And a phase change material layer Ge15Te85forming a high-reliability quasi-superlattice phase-change material layer by cyclic alternating superposition, wherein the amorphous Sb2Te3The energy required for crystallization of the layer is low and stable lattice orientation is easy to form, so the Sb2Te3 layer can be selected as an inducing layer to induce Ge in amorphous state15Te85The layer has higher phase change speed in the phase change process, and can promote the whole phase change material to be rapidly crystallized; and selected Ge15Te85In the band structure of the layer, defect states are mainly localized at the tail of the band, rather than defect levels near the fermi level in the band gap, which are not due to defectsthe relaxation of the trap level causes a resistance drift, and thus a higher phase change rate is achieved during the phase change.
2. according to the high-reliability phase change material, the phase change memory and the preparation method, due to the existence of the superlattice-like interface between the first phase change material layer and the second phase change material layer, the resistance drift is far lower than that of the traditional phase change material, the reliability of the device can be greatly improved on the premise of not changing the structure of the device and not consuming extra circuits, and the development requirement of the device with a small size can be met.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (10)
1. A high-reliability phase-change material is characterized in that: the phase change material layer is a superlattice-like phase change material layer (106) formed by circularly and alternately laminating a first phase change material layer (104) and a second phase change material layer (105), a superlattice-like interface is formed between the first phase change material layer (104) and the second phase change material layer (105), and the first phase change material layer (104) is Sb2Te3As an inducing layer, the second phase change material layer (105) is Ge15Te85The number of the layers which are overlapped in a circulating and alternating mode is at least three, and the bottom layer and the top layer are selected from one of the first phase change material layer (104) and the second phase change material layer (105).
2. A method for preparing a phase change material with high reliability as claimed in claim 1, wherein:
The preparation method comprises the step of depositing the first phase change material layer (104) and the second phase change material layer (105) alternately in a circulating mode through a deposition method comprising magnetron sputtering, electron beam evaporation, atomic layer deposition and chemical reaction deposition until the preparation of the superlattice-like phase change material layer (106) is completed.
3. The phase change memory is characterized by comprising the following components in sequence:
A layer of substrate material (100);
A first electrode (101);
An insulating medium material layer (103), wherein a contact hole (110) is formed in the insulating medium material layer (103);
A quasi-superlattice phase-change material layer (106) formed by circularly and alternately laminating a first phase-change material layer (104) and a second phase-change material layer (105), wherein a quasi-superlattice interface is formed between the first phase-change material layer (104) and the second phase-change material layer (105), and the first phase-change material layer (104) is Sb2Te3as an inducing layer, the second phase change material layer (105) is Ge15Te85The number of the layers is at least three, and the bottom layer and the top layer are selected from one of the first phase change material layer (104) and the second phase change material layer (105);
a second electrode (102);
the superlattice phase change material layer (106) is partially positioned in the contact hole (110) of the insulating medium material layer and is in contact with the first electrode (101).
4. The phase change memory of claim 3, wherein:
The contact area of the superlattice phase change material layer (106) and the first electrode (101) is smaller than the contact area of the second electrode (102) and the superlattice phase change material layer (106).
5. the high reliability phase change material of claim 3, wherein:
the bottom layers of the superlattice phase change material layer (106) are of a structure with grooves, and the top layer and the second electrode (102) are planar layers.
6. A method for manufacturing a phase change memory according to any one of claims 3 to 5, comprising the steps of:
S1: depositing a first electrode (101) on a layer of substrate material (100);
s2: depositing a layer of insulating dielectric material (103) over the first electrode (101);
S3: preparing a contact hole (110);
forming a contact hole (110) with a preset size on the local surface of the insulating medium material layer (103) by using photoetching;
s4: preparing a superlattice-like phase change material layer (106);
Forming an electrode pattern by using etching to align the first electrode (101) in the contact hole (110), and then cyclically and alternately depositing a first phase change material layer (104) and a second phase change material layer (105) in the contact hole and at the periphery by a deposition method until the preparation of the superlattice-like phase change material layer (106) is finished;
s5: preparing a second electrode (102);
After the preparation of the superlattice phase change material-like layer (106) is completed, a second electrode (102) is directly deposited thereon.
7. The method of manufacturing a phase change memory according to claim 6, wherein:
In steps S1, S2, S4, and S5, the deposition method employs any one of magnetron sputtering, electron beam evaporation, atomic layer deposition, and chemical reaction deposition.
8. the method of manufacturing a phase change memory according to claim 6, wherein:
in step S2, the thickness of the insulating medium material layer (103) is adjusted according to the thickness of the superlattice phase change material-like layer (106), and the thicker the design thickness of the later prepared superlattice phase change material-like layer (106), the thicker the thickness of the insulating medium material layer (103) deposited earlier.
9. The method of manufacturing a phase change memory according to claim 6, wherein:
In step S3, the photolithography method uses ultraviolet lithography or electron beam lithography.
10. the method of manufacturing a phase change memory according to claim 6, wherein:
In step S4, the etching method uses reactive ion etching or coupled plasma etching.
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