CN112397644B - Phase change material, phase change memory unit and preparation method thereof - Google Patents
Phase change material, phase change memory unit and preparation method thereof Download PDFInfo
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- 239000012782 phase change material Substances 0.000 title claims abstract description 126
- 230000008859 change Effects 0.000 title claims abstract description 70
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- 238000002360 preparation method Methods 0.000 title claims abstract description 11
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- 239000000463 material Substances 0.000 claims abstract description 34
- 229910052691 Erbium Inorganic materials 0.000 claims abstract description 18
- 229910052714 tellurium Inorganic materials 0.000 claims abstract description 14
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- 230000008569 process Effects 0.000 claims abstract description 5
- UYAHIZSMUZPPFV-UHFFFAOYSA-N erbium Chemical compound [Er] UYAHIZSMUZPPFV-UHFFFAOYSA-N 0.000 claims abstract description 4
- PORWMNRCUJJQNO-UHFFFAOYSA-N tellurium atom Chemical compound [Te] PORWMNRCUJJQNO-UHFFFAOYSA-N 0.000 claims abstract description 4
- FAWGZAFXDJGWBB-UHFFFAOYSA-N antimony(3+) Chemical compound [Sb+3] FAWGZAFXDJGWBB-UHFFFAOYSA-N 0.000 claims abstract description 3
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- 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
- H10N70/801—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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- 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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- 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
- H10N70/021—Formation of switching materials, e.g. deposition of layers
- H10N70/023—Formation of switching materials, e.g. deposition of layers by chemical vapor deposition, e.g. MOCVD, ALD
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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
- H10N70/026—Formation of switching materials, e.g. deposition of layers by physical vapor deposition, e.g. sputtering
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- H10N70/00—Solid-state devices having no potential barriers, and specially adapted for rectifying, amplifying, oscillating or switching
- H10N70/20—Multistable switching devices, e.g. memristors
- H10N70/231—Multistable switching devices, e.g. memristors based on solid-state phase change, e.g. between amorphous and crystalline phases, Ovshinsky effect
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Abstract
The invention provides a phase-change material, a phase-change memory cell and a preparation method thereof, wherein the phase-change material comprises erbium element, antimony element and tellurium element, and the chemical formula of the phase-change material is Er x Sb y Te z Wherein x, y, z each refer to an atomic composition of an element and satisfy 0<x/(x+y+z) is not more than 2/9, and 1/3 is not more than z/y is not more than 3/2. Er of the invention x Sb y Te z The phase change material has good thermal stability, higher data retention, faster crystallization speed and lower density change rate, and the phase change memory unit adopting the phase change material has higher operation speed and better cycle times, and the reliability of the device is greatly improved. Meanwhile, the phase change preparation method disclosed by the invention is simple in process and convenient for precisely controlling the material components.
Description
Technical Field
The invention belongs to the technical field of microelectronics, and relates to a phase change material, a phase change memory unit and a preparation method thereof.
Background
Phase Change Memory (PCM) is a nonvolatile semiconductor memory that has been rapidly developed in recent years. Compared with the traditional memory, the memory has the advantages of strong size scalability, high read-write speed, high data retention, low power consumption, long cycle life, excellent anti-irradiation performance and the like. Therefore, the phase change memory becomes a powerful competitor in various novel memory technologies, is extremely expected to replace Flash memory flash+DRAM technology, becomes a main stream memory technology of the next generation of non-volatile memory, and has wide market prospect. Meanwhile, it can produce new applications in some fields which are not achieved by the common memories, such as the fields of space, aerospace technology and military.
Application of phase change memory is based on reversible conversion of phase change material between high and low resistance under operation of electric pulse signal to realize writing and reading of ' 0 ' and ' 1And (5) wiping. The core of the phase change memory is a phase change memory medium material, and the traditional phase change material is mainly Ge 2 Sb 2 Te 5 Because of its good combination of properties, it has been widely used in phase-change optical discs and phase-change memories. However, there are still some problems with this material: 1) The crystallization temperature is low, the thermal stability is poor, the data retention is not guaranteed, and the risk of data loss is faced. For example, in the automotive electronics field, the temperature requirements for which the memory device may be in service are higher than 120 ℃, while Ge 2 Sb 2 Te 5 The working temperature of the data storage which can be provided for 10 years is only about 85 ℃; 2) The phase change speed is low, and researches show that the phase change is based on Ge 2 Sb 2 Te 5 The electric pulse for realizing stable SET operation of the phase change memory is at least of the order of hundred nanoseconds, and the electric pulse for realizing stable RESET operation also needs 20ns, so that the speed requirement of the dynamic random access memory cannot be met; 3) The density change is too large, and after crystallization, the density change rate reaches 6%, which is unfavorable for the reliability of the device.
Therefore, how to find a phase change film material with high speed, high data retention and low density change rate, so that the phase change film material has a wide temperature range working range, is an important technical problem to be solved by those skilled in the art.
Disclosure of Invention
In view of the above-mentioned drawbacks of the prior art, an object of the present invention is to provide a phase change material, a phase change memory cell and a method for manufacturing the same for solving the problems of the prior art of Ge 2 Sb 2 Te 5 The phase change material has low crystallization temperature, poor thermal stability, no guarantee of data retention, data loss, low device reliability and low phase change speed caused by too high density change rate before and after crystallization of the phase change material, and cannot meet the speed requirement of the dynamic random access memory.
To achieve the above and other related objects, the present invention provides a phase change material comprising erbium element, antimony element and tellurium element, wherein the chemical formula of the phase change material is Er x Sb y Te z Wherein x, y, z all refer to elementsAtomic composition, and satisfies 0<x/(x+y+z)≤2/9，1/3≤z/y≤3/2。
Optionally, the Er x Sb y Te z In the formula, x/(x+y+z) is more than or equal to 1/100 and less than or equal to 1/9, and z/y is more than or equal to 1/3 and less than or equal to 3/2.
Optionally, the Er x Sb y Te z In the formula, x is more than or equal to 0.01 and less than or equal to 0.35, y is more than or equal to 2, and z is more than or equal to 1.
Optionally, the Er x Sb y Te z In the formula, x is more than or equal to 0.03 and less than or equal to 0.3, y is more than or equal to 2, and z is more than or equal to 1.
Optionally, the Er x Sb y Te z In the formula, x is more than or equal to 0.05 and less than or equal to 0.25, y is more than or equal to 2, and z is more than or equal to 1.
The invention also provides a phase change memory cell, which comprises a phase change material layer, wherein the material of the phase change material layer comprises the phase change material as described in any one of the above.
Optionally, the thickness of the phase change material layer ranges from 40nm to 200nm.
Optionally, the phase change memory unit further includes a lower electrode layer, an adhesive layer and an extraction electrode layer, the phase change material layer is disposed on the lower electrode layer, the adhesive layer is disposed on the phase change material layer, and the extraction electrode layer is disposed on the adhesive layer.
Optionally, the materials of the lower electrode layer, the bonding layer and the extraction electrode layer respectively include at least one of W, pt, au, ti, al, ag, cu and Ni, or a nitride or an oxide of at least one of them.
The invention also provides a preparation method of the phase change material, which adopts any one of a magnetron sputtering method, a chemical vapor deposition method, an atomic layer deposition method and an electron beam evaporation method to prepare the phase change material.
Optionally, according to the chemical formula Er of the phase change material x Sb y Te z Adopts Er simple substance target and Sb y Te z And co-sputtering alloy targets to prepare the phase change material.
Optionally, the Er elemental target and the Sb are adopted y Te z In the co-sputtering process of the alloy targets, the background vacuum degree is less than 3.0x10 -4 Pa, sputtering gas including argon, sputtering pressure ranging from 0.40Pa to 0.45Pa, sputtering temperature ranging from 1 ℃ to 80 ℃ and sputtering time ranging from 10 minutes to 30 minutes.
The invention also provides a preparation method of the phase-change memory unit, which comprises the following steps:
forming a lower electrode layer;
forming a phase change material layer on the lower electrode layer, wherein the material of the phase change material layer comprises the phase change material according to any one of the above;
forming an adhesive layer on the phase change material layer,
forming an extraction electrode layer on the bonding layer.
Optionally, the methods for forming the lower electrode layer, the adhesive layer and the extraction electrode layer include any one of sputtering, evaporation, chemical vapor deposition, plasma enhanced chemical vapor deposition, low pressure chemical vapor deposition, metal compound vapor deposition, molecular beam epitaxy, atomic vapor deposition and atomic layer deposition, respectively; the method for forming the phase change material layer comprises any one of a magnetron sputtering method, a chemical vapor deposition method, an atomic layer deposition method and an electron beam evaporation method.
As described above, er of the present invention x Sb y Te z The phase change material can obtain storage materials with different crystallization temperatures, resistivities and crystallization activation energies by adjusting the content of Er elements, and the phase change material of the system has large difference of resistances before and after phase change and very strong adjustability, so that specific performances can be provided according to actual requirements. Wherein Er is as follows 0.17 Sb 2 Te has better data retention, and also has faster operation speed and better cycle number when being applied to a device unit in the phase change memory, thus being a suitable storage medium material for preparing the phase change memory. Er of the invention x Sb y Te z Phase change material, and conventional Ge 2 Sb 2 Te 5 Compared with the prior art, the heat-resistant material has better heat stability,stronger data retention, faster crystallization speed, lower density change rate. The preparation method of the phase change material provided by the invention is simple in process and convenient for precisely controlling the material components.
Drawings
FIG. 1 shows as Sb 2 Te and Er with different components provided by the invention x Sb y Te z Resistance versus temperature plot for phase change materials.
FIG. 2 shows as Sb 2 Te and Er with different components provided by the invention x Sb y Te z And calculating a result graph of the data retention capacity of the phase change material.
FIG. 3 shows the use of Er provided for the present invention 0.17 Sb 2 Fitting density change rate diagram of the phase change memory of Te phase change material.
FIG. 4 shows the use of Er provided for the present invention 0.17 Sb 2 Resistance-voltage relationship diagram of a phase change memory of Te phase change material.
FIG. 5 shows the use of Er provided for the present invention 0.17 Sb 2 Fatigue performance diagram of phase change memory of Te phase change material.
Detailed Description
Other advantages and effects of the present invention will become apparent to those skilled in the art from the following disclosure, which describes the embodiments of the present invention with reference to specific examples. The invention may be practiced or carried out in other embodiments that depart from the specific details, and the details of the present description may be modified or varied from the spirit and scope of the present invention.
Please refer to fig. 1 to 5. It should be noted that, the illustrations provided in the present embodiment merely illustrate the basic concept of the present invention by way of illustration, and only the components related to the present invention are shown in the drawings and are not drawn according to the number, shape and size of the components in actual implementation, and the form, number and proportion of the components in actual implementation may be arbitrarily changed, and the layout of the components may be more complex.
Example 1
In this embodiment, a phase change material is provided, where the phase change material includes erbium (Er) element, antimony (Sb) element, and tellurium (Te) element, and the chemical formula of the phase change material is Er x Sb y Te z Wherein x, y, z each refer to an atomic composition of an element and satisfy 0<x/(x+y+z)≤2/9，1/3≤z/y≤3/2。
Specifically, the Er x Sb y Te z The contents of the three elements Er, sb and Te can be adjusted to obtain the storage materials with different crystallization temperatures, resistivities and crystallization activation energies. For example, the Er x Sb y Te z Can further satisfy that x/(x+y+z) is more than or equal to 1/100 and less than or equal to 1/9, and z/y is more than or equal to 1/3 and less than or equal to 3/2.
As an example, the Er x Sb y Te z In the formula, the atomic composition ratio z/y of Te and Sb is 1/2, and when y=2 and z=1, the composition of Er satisfies 0.01-0.35. Of course, the atomic composition of Er can further satisfy 0.03.ltoreq.x.ltoreq.0.3, or further satisfy 0.05.ltoreq.x.ltoreq.0.25.
By way of example, the phase change material is present in the form of a thin film and the thickness of the thin film ranges from 40nm to 200nm.
Referring to FIG. 1, shown as Sb 2 Te and Er with different compositions x Sb y Te z Resistance versus temperature plot for phase change materials. In this example, three different compositions of Er are provided x Sb y Te z Phase change materials, er respectively 0.05 Sb 2 Te、Er 0.17 Sb 2 Te、Er 0.25 Sb 2 Te。
In this embodiment, not only Er x Sb y Te z Phase change material and Sb 2 Te is also compared with Ge 2 Sb 2 Te 5 (abbreviated as GST) is compared. Since GST is now studied in detail, its related data are not shown in this and the following examples.
As can be seen from fig. 1, er x Sb y Te z The crystallization temperature of the phase-change material can be adjusted between 190 ℃ and 240 ℃ compared with Sb 2 Te (about 150 ℃ C.) and Ge 2 Sb 2 Te 5 (about 150 ℃, not shown) is significantly improved.
In addition, it can be seen that Er x Sb y Te z The high-low resistance value of the phase-change memory material increases with the increase of the content of Er, and the crystallization temperature of the phase-change memory material increases with the increase of the content of Er. Therefore, the crystallization temperature of the Er-Sb-Te phase change material can be controlled by adjusting the content of Er.
Referring to FIG. 2, shown as Sb 2 Te and Er with different compositions x Sb y Te z And calculating a result graph of the data retention capacity of the phase change material. In this example, three different compositions of Er are provided x Sb y Te z Phase change materials, er respectively 0.05 Sb 2 Te (noted as sample EST-1), er 0.17 Sb 2 Te (noted as sample EST-2), er 0.25 Sb 2 Te (designated as sample EST-3). As can be seen from fig. 2, er x Sb y Te z The 10 year data retention temperature of the phase change material increases with increasing Er content. At the same time, it can be seen that Er x Sb y Te z 10 year data retention of Material System compared to Sb 2 Te and Ge 2 Sb 2 Te 5 (not shown) is greatly improved. Wherein Er is as follows 0.25 Sb 2 The data retention of Te was as high as 138 ℃. Thus, er x Sb y Te z The thermal stability and data retention of the phase change material can be optimized by adjusting the content of Er.
From the above, er of this example x Sb y Te z The phase change material has at least two stable resistance states under the action of electric pulse, can realize reversible conversion of high and low resistance values under the operation of electric pulse signals, and has the resistance value unchanged under the operation without the electric pulse signals, thus being a suitable storage medium material for preparing the phase change memory. At the same time, the Er x Sb y Te z The ten-year data retention of the phase change material is stronger, and compared with the traditional phase change material, the phase change material has better thermal stability and stronger data retention.
Example two
In the present embodimentA phase change memory cell is provided, the phase change memory cell comprising a phase change material layer comprising Er as described in embodiment one x Sb y Te z Phase change materials.
As an example, the thickness of the phase change material layer ranges from 40nm to 200nm.
As an example, the phase change memory cell further includes a lower electrode layer, an adhesive layer, and an extraction electrode layer, wherein the phase change material layer is disposed on the lower electrode layer, the adhesive layer is disposed on the phase change material layer, and the extraction electrode layer is disposed on the adhesive layer. The bonding layer is used for increasing the bonding degree between the upper electrode layer and the phase change material, and the bonding layer material is required to be stable in chemical property and not react with the phase change material in a higher temperature range. The extraction electrode layer is used for protecting the phase change material layer and is used as an upper electrode when the device is subjected to electrical test.
As an example, the materials of the lower electrode layer, the adhesive layer and the extraction electrode layer include at least one of W, pt, au, ti, al, ag, cu and Ni, or a nitride or an oxide of at least one of them, respectively. In this embodiment, the material of the extraction electrode layer is preferably Al, and the material of the adhesion layer is preferably TiN.
It should be noted that if the material of the extraction electrode layer is high in bonding strength with the phase change material, and does not react with the phase change material during heating, an adhesive layer may not be required, or the material of the adhesive layer and the extraction electrode layer may be considered to be the same.
Referring to FIG. 3, an illustration of Er is shown 0.17 Sb 2 Fitting density change rate diagram of a phase change memory of Te phase change material, wherein the phase change memory comprises a plurality of phase change memory units, and Er is adopted in the phase change memory units 0.17 Sb 2 The thickness of the phase change material layer of the Te phase change material is 40nm, and the density change rate after crystallization is 2.4% through calculation fitting. In contrast to Ge 2 Sb 2 Te 5 The 6% density change rate of the phase change material is already quite largeThe improvement is beneficial to further improving the reliability of the device.
Incidentally, with Sb 2 Te and Ge 2 Sb 2 Te 5 In comparison, er 0.05 Sb 2 Te、Er 0.25 Sb 2 The density change rate of the Te phase change material is similarly reduced (not shown). Thus, er-doped Er x Sb y Te z The reliability of the material system for the device is greatly improved.
Referring to FIG. 4, an illustration of Er is shown 0.17 Sb 2 Resistance-voltage relationship diagram of a phase change memory of Te phase change material. It can be seen that the phase change memory achieves a reversible phase change under the action of the electrical pulse. The voltage pulses used for the tests were 70 ns, 50 ns, 30 ns and 10 ns. Under the electric pulse of 70 nanoseconds, the phase change memory can be obtained to realize the operations of wiping (high resistance to low resistance) and writing (low resistance to high resistance) at 1.3V and 2.7V respectively.
Notably, er x Sb y Te z The phase change memory cell device prepared from the material can realize the erasing operation under the electric pulse as short as 10 nanoseconds, and the operation speed is far faster than that of Ge 2 Sb 2 Te 5 Operating speeds on the order of hundred nanoseconds of material. Wherein, er is adopted 0.17 Sb 2 The phase change memory of Te phase change material has operation voltages of 2.3V and 4.0V for wiping and writing of unit device under electric pulse of 10 nanoseconds.
The Er is adopted 0.05 Sb 2 Te、Er 0.17 Sb 2 Te、Er 0.25 Sb 2 The erasing speed of Te phase change memory cell device can reach 10ns, but the window RESET voltages are different and are respectively 4.9V (Er 0.05 Sb 2 Te)、4.1V(Er 0.17 Sb 2 Te)、5.5V(Er 0.25 Sb 2 Te). While three-component devices have higher RESET voltages and higher power consumption respectively with little difference in crystalline resistances. It can be seen that compared to Er 0.05 Sb 2 Te and Er 0.25 Sb 2 Te, er is adopted 0.17 Sb 2 Te phase-change material deviceWith lower power consumption.
Referring to FIG. 5, an illustration of Er is shown 0.17 Sb 2 Fatigue performance diagram of phase change memory of Te phase change material. As can be seen, the device repeatedly erases and writes up to 1.0X10 times without fatigue 5 And the high and low resistance states have stable resistance values, so that the reliability required by the application of the device is ensured.
The Er is adopted 0.05 Sb 2 Te phase change material or Er 0.25 Sb 2 The erasing and writing cycle times of the phase change memory of Te phase change material are all close to 5 multiplied by 10 4 Less times, relatively lower than using Er 0.17 Sb 2 Phase change memory of Te phase change material.
The phase change memory cell of this embodiment employs Er x Sb y Te z The phase change material enables the phase change memory to have higher operation speed, better cycle times and higher stability, and the reliability of the device can be further improved by the lower density change rate. Wherein Er is as follows 0.17 Sb 2 Te has better comprehensive performance, faster erasing speed and more cycle times.
Example III
In this embodiment, a method for preparing a phase change material is provided for preparing Er as described in embodiment one x Sb y Te z Phase change materials.
Specifically, any one of magnetron sputtering, chemical vapor deposition, atomic layer deposition and electron beam evaporation may be used for the Er x Sb y Te z Phase change materials. In this embodiment, the Er is preferably prepared by magnetron sputtering x Sb y Te z The phase change material can more conveniently adjust Er x Sb y Te z The contents of three elements in the phase change material are used for obtaining the storage materials with different crystallization temperatures, resistivities and crystallization activation energies.
As an example, er is according to the chemical formula of the phase change material x Sb y Te z Adopts Er simple substance target and Sb y Te z And co-sputtering alloy targets to prepare the phase change material.
In this example, the Er elemental targets and Sb were used 2 Co-sputtering Te alloy target to prepare Er x Sb 2 Te phase change material.
As an example, the Er elemental target adopts a radio frequency power source, and the sputtering power range of the radio frequency power source is 5W to 15W. The Sb is as follows 2 The Te alloy target adopts a radio frequency power supply, and the sputtering power of the radio frequency power supply is 20W. The Er with three components is obtained by adjusting the power of the Er simple substance target x Sb 2 Te phase change material: er (Er) 0.05 Sb 2 Te、Er 0.17 Sb 2 Te、Er 0.25 Sb 2 Te. Of course, in other embodiments, the Sb 2 The sputtering power employed for the Te alloy target may take other values, such as in the range of 10W-30W, without unduly limiting the scope of the invention herein.
As an example, in co-sputtering engineering, the background vacuum is less than 3.0X10 -4 Pa, sputtering gas including argon, sputtering pressure ranging from 0.40Pa to 0.45Pa, sputtering temperature ranging from 1 ℃ to 80 ℃ and sputtering time ranging from 10 minutes to 30 minutes. Phase change material layers with different thicknesses can be obtained by adjusting the sputtering time.
Example IV
The embodiment provides a preparation method of a phase change memory unit, which comprises the following steps:
s1: forming a lower electrode layer;
s2: forming a phase change material layer on the lower electrode layer, wherein the material of the phase change material layer comprises the phase change material in the first embodiment;
s3: forming an adhesive layer on the phase change material layer,
s4: forming an extraction electrode layer on the bonding layer.
As an example, the lower electrode layer may be prepared using any one of a sputtering method, an evaporation method, a chemical vapor deposition method, a plasma enhanced chemical vapor deposition method, a low pressure chemical vapor deposition method, a metal compound vapor deposition method, a molecular beam epitaxy method, an atomic vapor deposition method, and an atomic layer deposition method. The material of the lower electrode layer may include at least one of W, pt, au, ti, al, ag, cu and Ni, or may be at least one of nitride or oxide thereof. In this embodiment, the material of the lower electrode layer is preferably W.
As an example, the phase change material layer may be prepared using any one of a magnetron sputtering method, a chemical vapor deposition method, an atomic layer deposition method, and an electron beam evaporation method. In this embodiment, the Er is preferably prepared by magnetron sputtering x Sb y Te z The phase change material can more conveniently adjust Er x Sb y Te z The contents of three elements in the phase change material are used for obtaining the storage materials with different crystallization temperatures, resistivities and crystallization activation energies. Phase change material layers with different thicknesses can be obtained by adjusting the sputtering time.
As an example, the adhesive layer may be prepared using any one of a sputtering method, an evaporation method, a chemical vapor deposition method, a plasma enhanced chemical vapor deposition method, a low pressure chemical vapor deposition method, a metal compound vapor deposition method, a molecular beam epitaxy method, an atomic vapor deposition method, and an atomic layer deposition method. The bonding layer is used for enhancing the bonding force between the phase change material layer and the extraction electrode layer, and the material of the bonding layer can comprise at least one of W, pt, au, ti, al, ag, cu and Ni, or can be nitride or oxide of at least one of W, pt, au, ti, al, ag, cu and Ni. In this embodiment, the material of the adhesion layer is preferably TiN.
As an example, the extraction electrode layer may be prepared using any one of a sputtering method, an evaporation method, a chemical vapor deposition method, a plasma-enhanced chemical vapor deposition method, a low-pressure chemical vapor deposition method, a metal compound vapor deposition method, a molecular beam epitaxy method, an atomic vapor deposition method, and an atomic layer deposition method. The material of the extraction electrode layer may include at least one of W, pt, au, ti, al, ag, cu and Ni, or may be a nitride or an oxide of at least one of them. In this embodiment, the material of the lower electrode layer is preferably Al.
In conclusion, er of the invention x Sb y Te z The phase-change material can be used asThe storage materials with different crystallization temperatures, resistivities and crystallization activation energies are obtained by adjusting the content of Er element, and the phase change material of the system has large resistance difference before and after phase change and very strong adjustability, so that specific performances can be provided according to actual requirements. Wherein Er is as follows 0.17 Sb 2 Te has better data retention, and also has faster operation speed and better cycle number when being applied to a device unit in the phase change memory, thus being a suitable storage medium material for preparing the phase change memory. Er of the invention x Sb y Te z Phase change material, and conventional Ge 2 Sb 2 Te 5 Compared with the prior art, the method has better thermal stability, stronger data retention, faster crystallization speed, lower rate of density change. The preparation method of the phase change material provided by the invention is simple in process and convenient for precisely controlling the material components. Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.
The above embodiments are merely illustrative of the principles of the present invention and its effectiveness, and are not intended to limit the invention. Modifications and variations may be made to the above-described embodiments by those skilled in the art without departing from the spirit and scope of the invention. Accordingly, it is intended that all equivalent modifications and variations of the invention be covered by the claims, which are within the ordinary skill of the art, be within the spirit and scope of the present disclosure.
Claims (14)
1. A phase change material, characterized by: the phase change material comprises erbium element, antimony element and tellurium element, and the chemical formula of the phase change material is Er x Sb y Te z Wherein x, y, z each refer to an atomic composition of an element and satisfy 0<x/(x+y+z)≤2/9，1/3≤z/y≤3/2。
2. The phase change material of claim 1, wherein: the Er is x Sb y Te z In the formula, x/(x+y+z) is more than or equal to 1/100 and less than or equal to 1/9, and z/y is more than or equal to 1/3 and less than or equal to 3/2.
3. The phase change material of claim 1, wherein: the Er is x Sb y Te z In the formula, x is more than or equal to 0.01 and less than or equal to 0.35, y is more than or equal to 2, and z is more than or equal to 1.
4. The phase change material of claim 1, wherein: the Er is x Sb y Te z In the formula, x is more than or equal to 0.03 and less than or equal to 0.3, y is more than or equal to 2, and z is more than or equal to 1.
5. The phase change material of claim 1, wherein: the Er is x Sb y Te z In the formula, x is more than or equal to 0.05 and less than or equal to 0.25, y is more than or equal to 2, and z is more than or equal to 1.
6. A phase change memory cell, characterized by: the phase change memory cell comprises a phase change material layer, wherein the phase change material layer comprises the phase change material as claimed in any one of claims 1-5.
7. The phase change memory cell of claim 6, wherein: the thickness of the phase change material layer ranges from 40nm to 200nm.
8. The phase change memory cell of claim 6, wherein: the phase change memory unit further comprises a lower electrode layer, an adhesive layer and an extraction electrode layer, wherein the phase change material layer is arranged on the lower electrode layer, the adhesive layer is arranged on the phase change material layer, and the extraction electrode layer is arranged on the adhesive layer.
9. The phase change memory cell of claim 8, wherein: the materials of the lower electrode layer, the bonding layer and the extraction electrode layer respectively comprise at least one of W, pt, au, ti, al, ag, cu and Ni or nitride or oxide of at least one of W, pt, au, ti, al, ag, cu and Ni.
10. A preparation method of a phase change material is characterized by comprising the following steps: the phase change material according to any one of claims 1 to 5 is prepared by any one of magnetron sputtering, chemical vapor deposition, atomic layer deposition and electron beam evaporation.
11. The method of preparing a phase change material according to claim 10, wherein: according to the chemical formula Er of the phase change material x Sb y Te z Adopts Er simple substance target and Sb y Te z And co-sputtering alloy targets to prepare the phase change material.
12. The method of preparing a phase change material according to claim 11, wherein: adopting the Er simple substance target and the Sb y Te z In the co-sputtering process of the alloy targets, the background vacuum degree is less than 3.0x10 -4 Pa, sputtering gas including argon, sputtering pressure ranging from 0.40Pa to 0.45Pa, sputtering temperature ranging from 1 ℃ to 80 ℃ and sputtering time ranging from 10 minutes to 30 minutes.
13. A method of fabricating a phase change memory cell, comprising the steps of:
forming a lower electrode layer;
forming a phase change material layer on the lower electrode layer, wherein the material of the phase change material layer comprises the phase change material according to any one of claims 1-5;
forming an adhesive layer on the phase change material layer,
forming an extraction electrode layer on the bonding layer.
14. The method of fabricating a phase change memory cell according to claim 13, wherein: the methods for forming the lower electrode layer, the adhesive layer and the extraction electrode layer respectively comprise any one of a sputtering method, an evaporation method, a chemical vapor deposition method, a plasma enhanced chemical vapor deposition method, a low-pressure chemical vapor deposition method, a metal compound vapor deposition method, a molecular beam epitaxy method, an atomic vapor deposition method and an atomic layer deposition method; the method for forming the phase change material layer comprises any one of a magnetron sputtering method, a chemical vapor deposition method, an atomic layer deposition method and an electron beam evaporation method.
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