CN110729400A - Ti-Ga-Sb phase-change material, phase-change memory and preparation method of Ti-Ga-Sb phase-change material - Google Patents
Ti-Ga-Sb phase-change material, phase-change memory and preparation method of Ti-Ga-Sb phase-change material Download PDFInfo
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Abstract
The invention discloses a Ti-Ga-Sb phase-change material, a phase-change memory and a preparation method of the Ti-Ga-Sb phase-change material, belonging to the field of phase-change memory materialsxGaySb100‑x‑yThe material of (1) is obtained by taking Sb as a base material and doping Ti and Ga into the base material; wherein x and y are atomic number percentage respectively, x is more than 0 and less than 50, y is more than 0 and less than 50, and x + y is more than 0 and less than 60. The Ti-Ga-Sb phase-change material is simple and convenient in preparation method, compared with the traditional phase-change material, the prepared Ti-Ga-Sb phase-change material has smaller phase-change density difference, the crystallization efficiency of the phase-change material can be greatly improved while the thermal stability of the phase-change material is ensured, the stability and the accuracy of information data storage of the phase-change material are ensured, the information storage efficiency of a phase-change memory is improved, and the functionality of the phase-change memory is greatly improved while the service life of the phase-change memory is prolonged.
Description
Technical Field
The invention belongs to the field of phase change storage materials, and particularly relates to a Ti-Ga-Sb phase change material and a preparation method thereof, and application of the Ti-Ga-Sb phase change material in a phase change memory.
Background
In the big data age, the memory has more and more prominent position, and no matter the storage of information data or the transmission of information data, new challenges are provided for the traditional memory, and the development of a novel memory also becomes an important ring of technical innovation. The phase change memory is an excellent nonvolatile memory device, has the characteristics of high read-write speed, large capacity, low production cost and the like, and is one of the most promising next-generation memory devices at present. The phase change memory mainly utilizes the resistance difference between the crystalline state and the amorphous state of the phase change material to realize the function of information storage, and in the using process, the erasing function can be realized only by controlling the size and the time of a current pulse, and simultaneously, the stored information can be read out by a smaller current pulse.
For phase change memories, the performance depends to a large extent on the properties of the phase change material. At present, a phase change material which is mature in application, such as a Ge-Sb-Te based phase change material, has a sufficiently large crystalline-to-amorphous resistance difference, can realize reversible conversion between a stable crystalline state and an amorphous state, can ensure a sufficient resistance difference and a fast phase change speed, and has good stability at normal temperature. However, the crystallization temperature and ten-year data retention temperature of the existing phase-change material are both low, for example, the crystallization temperature of the Ge-Sb-Te phase-change material is 150 ℃, the ten-year data retention temperature is 85 ℃, and the amorphous state thermal stability of the material is poor; this greatly restricts the application of phase change materials in extreme environments.
Meanwhile, when the phase change memory material in the existing phase change memory is used, a large density difference often exists between the crystalline state and the amorphous state, for example, in the amorphous Ge-Sb-Te phase change material, lone pair electrons of the chalcogenide Te element can cause formation of a large number of vacancies, so that a large number of voids are generated inside the phase change material, and the density difference between the crystalline state and the amorphous state is large, and is usually more than 8%. The large phase change density difference far exceeds the influence of expansion with heat and contraction with cold of the phase change material, which easily causes the phase change material to generate cavities in the phase change process, and the cavities are usually gradually gathered at the electrode in the working process, so that the phase change material and the electrode are separated, finally causing the device failure, and influencing the application reliability and the service life of the phase change memory.
Disclosure of Invention
Aiming at one or more of the defects or the improvement requirements of the prior art, the invention provides a Ti-Ga-Sb phase-change material and a preparation method thereof, and provides a phase-change memory applying the Ti-Ga-Sb phase-change material.
In order to achieve the above object, according to one aspect of the present invention, there is provided a Ti-Ga-Sb phase change material, wherein the Ti-Ga-Sb phase change material is Ti, Sb, and the chemical formula of the composition of Ga elements is TixGaySb100-x-yThe material of (a); wherein x and y are atomic number percentage respectively, x is more than 0 and less than 50, y is more than 0 and less than 50, and x + y is more than 0 and less than 60.
As a further improvement of the invention, the value ranges of the x and y values are as follows: x is more than or equal to 10 and less than or equal to y is less than or equal to 30.
In another aspect of the present invention, a phase change memory is provided, which uses the Ti-Ga-Sb phase change material as a phase change memory material, wherein the Ti-Ga-Sb phase change material is a phase change thin film material with a thickness of 20 to 200nm in the phase change memory.
As a further improvement of the invention, the phase change film material is Ti20Ga30Sb50A phase change film material.
As a further improvement of the invention, the Ti-Ga-Sb phase-change material can be prepared by adopting a magnetron co-sputtering method, an electron beam evaporation method, a vapor deposition method or an atomic layer deposition method.
In another aspect of the invention, a preparation method of a Ti-Ga-Sb phase-change material is provided for preparing the phase-change thin film material, which adopts a magnetron co-sputtering method and comprises the following steps,
s1: selecting a sputtering substrate with a corresponding size according to the size of the phase-change film material, and cleaning the sputtering substrate;
s2: respectively preparing a Ga-Sb alloy target and a Ti simple substance target, and correspondingly arranging the positions of the two targets and the sputtering substrate;
s3: adopting high-purity inert gas as sputtering gas, and adjusting the flow and sputtering pressure of the sputtering gas;
s4: respectively setting the sputtering power of the Ga-Sb alloy target and the Ti simple substance target, preparing the phase-change thin film material by adopting a double-target co-sputtering method, and preparing the phase-change thin film material with different thicknesses by controlling the sputtering time.
As a further improvement of the invention, the Ga-Sb alloy target is Ga20Sb80Alloy target and Ga30Sb70Alloy target or Ga40Sb60An alloy target.
As a further improvement of the present invention, the sputtering substrate in the step S1 is SiO2a/Si (100) substrate.
In a further improvement of the present invention, in step S4, the sputtering power of the Ga-Sb alloy target is 30 to 40W, and the sputtering power of the Ti elemental target is 3 to 10W.
As a further improvement of the present invention, before step S4 is started, the surface cleaning process of the Ga-Sb alloy target and the Ti elemental target is also performed by the following method:
and rotating the hollow substrate to target positions which are aligned with the Ga-Sb alloy target and the Ti simple substance target, opening the baffle plates of the two target positions, and pre-sputtering for 5-10 min.
As a further improvement of the invention, the sputtering time in the step S4 is 2-15 min.
Generally, compared with the prior art, the above technical solution conceived by the present invention has the following beneficial effects:
(1) the Ti-Ga-Sb phase-change material is obtained by mutually doping Ti, Ga and Sb, Ga atoms, Ti atoms and Sb atoms are uniformly and randomly distributed and bonded in an amorphous Ti-Ga-Sb phase-change material, so that the Ti-Ga-Sb phase-change material has no obvious phase separation and becomes a stable ternary alloy, and the amorphous Ti-Ga-Sb phase-change material forms a tetrahedral structure taking Ga atoms as the center, so that the stability of the phase-change material in an amorphous state is effectively improved, the amorphous density of the phase-change material is effectively increased, the density difference of the phase-change material in the crystalline state and the amorphous state is reduced, the volume stability of the phase-change material in the phase-change process is improved, and the formation of cavities of the phase-change material in the crystalline state-amorphous state conversion is reduced, the phase change material in the phase change memory is prevented from being separated from the electrode, so that the application reliability of the phase change memory is improved, the service life of the phase change memory is prolonged, and the phase change memory can still keep normal work under long-time repeated erasing and writing;
(2) according to the Ti-Ga-Sb phase-change material, the defect octahedral structure is formed by taking Ti atoms as the center, so that the nucleation time in the crystallization process of the phase-change material can be effectively reduced, the crystallization process of the phase-change material is accelerated, and the ultra-fast phase change of the phase-change material is realized, so that the ultra-fast read-write operation of the Ti-Ga-Sb phase-change material can be realized, the data read-write efficiency of a phase-change memory is improved, and the convenience and the functionality of the application of the phase-change memory are improved;
(3) the Ti-Ga-Sb phase-change material can realize the control and adjustment of the properties of the Ti-Ga-Sb phase-change material by regulating the proportion of Ti and Ga in the phase-change material, so that the properties of the phase-change material, such as poor phase-change density, crystallization rate, thermal stability and the like, are unified to a certain degree, and the stable and reliable application of the Ti-Ga-Sb phase-change material is met20Ga30Sb50The appearance is particularly obvious in the phase change material; meanwhile, the possibility of preparing the phase-change material with different performance requirements is provided by regulating and controlling the contents of Ti and Ga, the application requirements in different phase-change memories are met, the application range of the phase-change material is effectively expanded, and the use cost of the phase-change memory is reduced;
(4) the preparation method of the Ti-Ga-Sb phase-change material utilizes the magnetron co-sputtering method to prepare, has simple steps and simple and convenient operation, and can effectively realize the preparation of Ti-Ga-Sb phase-change materials with different compositions and different performances by controlling the composition of the Ga-Sb alloy target and the power of the direct-current sputtering power supply of the Ti simple substance target; meanwhile, the forming thickness of the phase-change material can be accurately controlled by controlling the sputtering time, namely the thickness, the phase-change density difference, the crystallization temperature and the resistivity of the Ti-Ga-Sb phase-change material can be adjusted by controlling corresponding parameters in the preparation method, so that the phase-change materials with different thicknesses and different performance requirements are prepared, and the application of the phase-change materials in different phase-change memories is met.
Drawings
FIG. 1 is a structural diagram of an amorphous atom of a Ti-Ga-Sb phase-change material calculated based on first-nature-principle molecular dynamics simulated annealing according to a first embodiment of the present invention;
FIG. 2 is an R-T curve of an annealing process of a Ti-Ga-Sb phase-change material prepared in the first embodiment of the invention;
FIG. 3 is a voltage-resistance relationship curve of the Ti-Ga-Sb phase-change material prepared in the first embodiment of the invention under the action of voltage pulse;
FIG. 4 is a comparison of the crystalline state and amorphous state densities of the Ti-Ga-Sb phase-change material prepared in the example of the invention through AFM measurement and first-order simulation calculation.
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 phase change memory material which can be used for the phase change memory in the preferred embodiment of the invention is a Ti-Ga-Sb material, which is an alloy material consisting of Ti element (titanium), Sb element (antimony) and Ga element (gallium), and can be obtained by taking Sb as a base material and doping Ti and Ga into the base material, and the phase change density difference, the crystallization temperature and the resistivity of the alloy material are controlled by controlling the contents of Ti and Ga. Furthermore, the general formula of the chemical composition of the Ti-Ga-Sb phase-change material is TixGaySb100-x-yWherein x is more than 0 and less than 50, y is more than 0 and less than 50, and x + y is more than 0 and less than 60.
The above Ti is used for obtaining better material thermal stability and ensuring that the density difference of the phase-change material when the crystalline state and the amorphous state are transformed is small enoughxGaySb100-x-yThe values of x and y in the phase change material may preferably be: x is more than or equal to 10 and less than or equal to y is less than or equal to 30.
Specifically, when x is 20 and y is 30, Ti is obtained20Ga30Sb50The density difference of the phase-change material is minimum when the crystalline state and the amorphous state are converted, the phase-change speed can reach at least 10ns, and the phase-change material has good amorphous stability and extremely low power consumption and is a phase-change storage material with excellent performance.
Further, the Ti-Ga-Sb phase change material in the preferred embodiment can be prepared by a magnetron sputtering method, an electron beam evaporation method, a vapor deposition method, or an atomic layer deposition method. Meanwhile, the Ti-Ga-Sb phase-change material in the preferred embodiment can be used for manufacturing a phase-change memory device with high stability and high reliability, when the Ti-Ga-Sb phase-change material is applied to a phase-change memory, the Ti-Ga-Sb phase-change material is often processed into a Ti-Ga-Sb phase-change thin film material, and the thickness of the phase-change thin film material is 20-200 mm at most.
The Ti-Ga-Sb phase change material in the preferred embodiment is an ultrafast phase change memory material which can realize reversible conversion between high resistance and low resistance under the condition of applying nanosecond-level electric pulse signals, the change amplitude of the high resistance and the low resistance is more than two orders of magnitude, and the two different resistance states can be just used for representing stored logic '0' state and '1' state respectively.
In view of the above resistance reversible change characteristic of Ti-Ga-Sb phase change material, it can be used to construct an electrically erasable non-volatile memory.
The first embodiment is as follows:
in the embodiment, the chemical general formula of the nano Ti-Ga-Sb phase-change thin film material used in the phase-change memory is TixGaySb100-x-yWherein x is 9.7 and y is 18.5, namely the chemical formula of the Ti-Ga-Sb phase-change material is Ti9.7Ga18.5Sb71.8。
The Ti-Ga-Sb nano film material in the embodiment is preferably prepared by adopting a magnetron co-sputtering method.
Specifically, the target is prepared by selecting a corresponding Ga-Sb alloy target and a Ti simple substance target to carry out double-target co-sputtering, wherein the Ga-Sb alloy target selected in the embodiment is Ga20Sb80An alloy target.
During preparation, high-purity inert gas is used as sputtering gas, the volume percentage of the high-purity inert gas reaches over 99.999 percent, and the sputtering gas pressure is preferably adjusted to 0.5 Pa; in a preferred embodiment, high-purity argon gas with a gas purity of not less than 99.999% is used as the sputtering gas. At the same time, Ga20Sb80The alloy target preferably adopts a direct current power supply, and the power of the power supply is 36W; the Ti simple substance target preferably adopts a direct current power supply, and the power of the power supply is 4W. Of course, the Sb target and the Ga target may also be ac power supplies, and the power supplies of the two power supplies may be adjusted correspondingly.
Specifically, Ti9.7Ga18.5Sb71.8The preparation method of the phase-change film material comprises the following steps:
s1: selecting a sputtering substrate with a certain size, preferably SiO with a size of 1cm × 1cm2the/Si (100) substrate is cleaned on the surface and the back surface to remove dust particles, organic and inorganic impurities. The size of the sputtering substrate is selected to correspond to the size of the phase-change thin film material to be obtained, for example, in the preferred embodiment, phase-change thin film materials with different thicknesses with the size of 1cm × 1cm can be obtained.
The cleaning process for the substrate in the preferred embodiment is as follows:
s11: mixing SiO2Carrying out ultrasonic treatment on a Si (100) substrate in an acetone solution for 10min by using 40W power, and washing by using deionized water;
s12: the treated substrate is treated by ultrasonic treatment for 10min in ethanol solution with 40W of power, washed by deionized water and then treated by high-purity N2And air-drying the surface and the back to obtain the substrate to be sputtered.
S2: the preparation of Ti by adopting a direct current sputtering method is carried out9.7Ga18.5Sb71.8Preparation of the phase change film material.
S21: respectively filled with Ga20Sb80The purity of the alloy target and the Ti elementary substance target respectively reach99.99% (atomic%) and the background is evacuated to 10 deg.C-4Pa；
S22: using high-purity argon as sputtering gas, setting the flow stability of the argon to be 10sccm, and adjusting the sputtering pressure to 0.5Pa and the distance between the target and the substrate to be 150 mm;
s23: ga is set separately20Sb80The power of a direct-current sputtering power supply of the alloy target is 36W, and the power of a direct-current sputtering power supply of the Ti simple substance target is 4W.
S3: the Ti-Ga-Sb nanometer phase change film material is prepared by a direct current double-target co-sputtering method.
S31: while rotating the empty susceptor to Ga20Sb80Opening baffles at two target positions of a target position of the alloy target and a target position of the Ti simple substance target, and performing pre-sputtering for 5-10 min to clean the surface of the target;
s32: to Ga20Sb80After the surfaces of the alloy target and the Ti simple substance target are cleaned, the baffle plates of the two target positions are closed, and the substrate to be sputtered is rotated to Ga20Sb80And opening the baffles of the two target positions between the target position of the alloy target and the target position of the Ti simple substance target, starting double-target co-sputtering and obtaining the Ti-Ga-Sb phase change film with the corresponding thickness.
According to the difference of the sputtering time, Ti-Ga-Sb phase-change films with different thicknesses can be obtained. When the sputtering time is 2min, the prepared Ti-Ga-Sb phase-change film is about 20nm and can be used for measuring the X-ray reflectivity; when the sputtering time is 15min, the thickness of the prepared Ti-Ga-Sb phase-change film is about 200nm, and the Ti-Ga-Sb phase-change film can be used for in-situ resistivity annealing measurement and AFM measurement. Meanwhile, the chemical composition formula of the thin film material prepared in the embodiment is Ti, which can be determined by quantitative analysis of X-ray photoelectron spectrometer (XPS)9.7Ga18.5Sb71.8。
After analyzing the Ti-Ga-Sb phase-change thin film material obtained in the above example, it was found that, in the amorphous Ti-Ga-Sb model calculated based on the first-principle molecular dynamics simulated annealing, three elements of Ti, Ga, and Sb were uniformly and randomly distributed and bonded, and there was no significant phase separation, as shown in fig. 1. Meanwhile, analysis shows that the combination of Ga and Sb in the amorphous phase-change material tends to form a tetrahedron, the formation of the tetrahedron structure increases the difference with a crystalline structure on one hand, so that the stability of the amorphous phase-change material can be improved, and on the other hand, the Ga-Sb bond in the amorphous phase-change material is shorter, the stacking efficiency is higher, and the density of the amorphous phase-change material is effectively increased to be closer to the density of the crystal. In addition, Ti elements tend to form defective octahedra, and these octahedra structures can reduce nucleation time during crystallization to accelerate the crystallization process.
The local structure of the amorphous Ti-Ga-Sb phase-change material explains the action and mechanism of Ga and Ti elements in a system; meanwhile, Ga atoms and Ti atoms are bonded and form a tetrahedral or defected octahedral structure, whether the defected octahedral structure and the tetrahedral structure coexist or not and the proportion of the defect octahedral structure and the tetrahedral structure in coexistence is directly related to the contents of Ga and Ti, the doping of Ti directly determines the crystallization speed of the material, and the doping of Ga can increase the amorphous stability and reduce the phase transition density difference but possibly sacrifice a certain crystallization speed. Therefore, according to the requirements of different application environments, the control and adjustment of the properties of the Ti-Ga-Sb phase-change material can be realized by regulating the ratio of Ti to Ga in the Ti-Ga-Sb phase-change material, and the most appropriate material is manufactured.
Further, FIG. 2 shows the annealed R-T curve of the Ti-Ga-Sb phase-change material obtained in the present example. The as-deposited films obtained by the sputtering process tend to be in the amorphous state and have a resistance higher than 105Ω, a logic "0" for representing a high resistance state; as the annealing process proceeds, the phase-change thin film material crystallizes and its resistance drops to 103The low resistance state of Ω is used to represent a logic "1" for the low resistance state. Meanwhile, it is easy to see that the resistance of the Ti-Ga-Sb phase-change material is suddenly and obviously reduced at about 200 ℃. Thus, Ti was confirmed9.7Ga18.5Sb71.8The crystallization temperature of the phase-change thin film material is about 200 ℃, which is higher than that of the traditional Ge-Sb-Te phase-change material, and shows that the crystallization temperature of the Ti-Ga-Sb phase-change material is improved to a certain extent and the thermal stability is enhanced compared with that of the traditional Ge-Sb-Te phase-change material.
Further, FIG. 3 shows that the Ti-Ga-Sb phase-change material obtained in the present example is electrically conductiveVoltage-resistance curve under the action of voltage pulse. It can be seen from the graph that the transition of high and low resistance values can still be realized at a pulse width of 10ns, indicating that Ti9.7Ga18.5Sb71.8The phase-change film material has an ultrafast phase-change speed, and can realize 10ns of ultrafast read-write operation, and the property enables the ultrafast data read-write operation to be realized when the phase-change film material is applied in a phase-change memory, so that the efficiency of data storage is improved.
Analysis shows that the octahedral structure formed by Ti element is the main reason that the Ti-Ga-Sb phase-change material can realize ultra-fast phase change, and the existence of the octahedral structure accelerates the formation of crystal nucleus. As a typical brittle glass, an amorphous state can be kept stable at normal temperature, the atom movement speed is slow, and the octahedral structures can be kept unchanged; when the temperature rises to the crystallization temperature, a rapid crystallization process is started, the atom movement speed is greatly accelerated, nucleation is rapidly completed on the basis of the octahedrons, the whole crystallization process is greatly accelerated in the crystallization process mainly based on the nucleation, and therefore much nucleation time is saved.
Further, by changing the corresponding conditions in the preparation method of the first embodiment, Ti-Ga-Sb phase change materials with different compositions and different properties can be prepared, as shown in the following several embodiments.
Example two:
in this embodiment, the preparation method of the Ti-Ga-Sb phase-change thin film material is the same as the above steps, and the biggest difference is that Ga in step S21 is used20Sb80Replacement of alloy targets by Ga30Sb70And (4) alloying the target, and adjusting the power of the direct-current sputtering power supply of the Ti simple substance target in the step S23 to 9W.
After the magnetron co-sputtering process, Ti-Ga-Sb phase-change film materials with different thicknesses can be obtained according to different sputtering time. After quantitative analysis by X-ray photoelectron spectroscopy (XPS), the chemical composition formula of the thin film material obtained in this example is Ti19.1Ga24.2Sb56.7。
Example three:
in this example, the preparation method of the Ti-Ga-Sb phase change thin film material is the same as that of the second example, except that Ga in step S21 is used30Sb70Replacement of alloy targets by Ga40Sb60The power of the direct-current sputtering power supply of the Ti simple substance target is still 9W.
After the magnetron co-sputtering process, Ti-Ga-Sb phase-change film materials with different thicknesses can be obtained according to different sputtering time. After quantitative analysis by X-ray photoelectron spectroscopy (XPS), the chemical composition formula of the thin film material obtained in this example is Ti19.1Ga30.6Sb50.3。
Example four:
in this embodiment, the preparation method of the Ti-Ga-Sb phase-change thin film material is the same as that of the first embodiment, except that Ga in step S21 is used20Sb80Replacement of alloy targets by Ga30Sb70And (4) alloying the target, and adjusting the power of the direct current sputtering power supply of the Ti simple substance target in the step S23 to be 6W.
After the magnetron co-sputtering process, Ti-Ga-Sb phase-change film materials with different thicknesses can be obtained according to different sputtering time. After quantitative analysis by X-ray photoelectron spectroscopy (XPS), the chemical composition formula of the thin film material obtained in this example is Ti14.3Ga25.6Sb60.1。
It can be seen that, by using the magnetron co-sputtering method in the first embodiment, Ti-Ga-Sb phase-change thin film materials with different thicknesses can be obtained according to different sputtering times; meanwhile, by changing the sputtering power supply power of the Ga-Sb alloy target and the Ti elementary substance target and/or the composition of the Ga-Sb alloy target, Ti-Ga-Sb phase-change materials with different compositions can be correspondingly obtained, and the chemical composition general formula of the obtained Ti-Ga-Sb phase-change film material meets the requirement of Ti-Ga-Sb phase-change film materialxGaySb100-x-yWherein x is more than 0 and less than 50, y is more than 0 and less than 50, and x + y is more than 0 and less than 60.
Specifically, in the preferred embodiment, in order to obtain the phase-change thin film material with the above chemical composition, the sputtering power of the Ga-Sb alloy target is 30-40W, and the sputtering power of the Ti single-substance target is 3-1The 0W, Ga-Sb alloy target may be Ga20Sb80Alloy target and Ga30Sb70Alloy target or Ga40Sb60An alloy target.
Further, it can be seen from experimental analysis of the phase change materials obtained in the second, third and fourth embodiments that each of the phase change materials has better amorphous thermal stability as the phase change material obtained in the first embodiment. Meanwhile, according to the voltage pulse test results, the phase change thin film materials obtained in the second, third and fourth embodiments can realize the conversion of high and low resistance values under the voltage pulse with the pulse width of 10ns, and the obtained Ti-Ga-Sb phase change thin film materials have the capability of rapid phase change, and can improve the data reading and writing efficiency of the phase change memory when being applied to the phase change memory.
Further, fig. 4 shows the density comparison of different Ti-Ga-Sb phase change materials in crystalline and amorphous states, respectively, obtained by AFM measurements and first-principles simulation calculations. It is found by comparative analysis that the content of Ga element is in direct proportion to the amorphous density. On the one hand, because of Ga element and Sb, Ti element can form Ga-Sb bond and Ga-Ti bond with shorter bond length, and coordination number of Ga atom is larger, which means that the same amount of Ga and coordination atom thereof only needs smaller volume, namely, stacking efficiency is increased; on the other hand, compared with the traditional GST material, the Ti-Ga-Sb material system has no sulfur system elements, and a large number of vacancies do not exist in the amorphous state, so the density of the amorphous Ti-Ga-Sb material is mainly controlled by the content of the Ga element, and the phase change density of the obtained phase change alloy material is less changed.
As can be seen from fig. 4, while the Ga content increases, the density difference of the phase change material in the amorphous and crystalline states gradually decreases, and is at 30% Ga and 20% Ti (i.e. Ti20Ga30Sb50Medium) gave the smallest difference in phase transition density, which indicates that Ti is present20Ga30Sb50The phase change material can be used as a phase change storage material with high reliability, and can realize more cycle phase change times and longer service life. Meanwhile, the voltage pulse test result shows that the voltage pulse test method is used for testing the voltage pulseTi20Ga30Sb50The phase change material can also realize a rapid phase change process of 10ns, namely Ti can be determined20Ga30Sb50The phase change material is a phase change storage material which can simultaneously ensure rapid phase change, high thermal stability and ultra-low phase change density change, thereby being stably applied to a phase change memory.
In summary, it is obvious that the Ti-Ga-Sb phase change material prepared in the preferred embodiment of the present invention can be used as a phase change memory material with fast phase change and low phase change density difference. Among them, the contents of Ga and Ti affect the phase transition speed and the density change, respectively, and they affect each other, so that it is necessary to select an appropriate ratio. According to the AFM measurement and the calculation result of the first principle, Ti can be obtained20Ga30Sb50The phase change material can realize near-zero density change in the phase change process, so that the phase change material is based on Ti20Ga30Sb50The phase change memory of the phase change material has better reliability, can effectively reduce the formation of cavities in the conversion process of the phase change material from a crystalline state to an amorphous state, and avoids the separation of the phase change material from an electrode, thereby improving the application reliability of the phase change memory, prolonging the service life of the phase change memory, and ensuring that the phase change memory can still keep normal work under long-time repeated erasing and writing.
The Ti-Ga-Sb phase-change material has simple and convenient preparation method, the prepared Ti-Ga-Sb phase-change material has lower phase-change density change, can be used as a stable phase change storage material to be applied to a phase change memory, ensures that the phase change memory can still keep normal work under long-time repeated erasing and writing, improves the application stability of the phase change memory and the accuracy of data storage, leads the phase change memory to have longer service life, moreover, the Ti-Ga-Sb phase-change material can realize rapid phase change and has higher crystallization temperature, can greatly improve the read-write efficiency of the phase-change material while effectively improving the thermal stability of the phase-change material, therefore, the efficiency of the phase change memory for storing data is improved, the requirements of the phase change memory for accurately and quickly storing information data are met, and the phase change memory has a good application prospect and a good popularization value.
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. The Ti-Ga-Sb phase-change material is characterized in that the Ti-Ga-Sb phase-change material is Ti, Sb and Ga, and the chemical general formula of the Ti-Ga-Sb phase-change material is TixGaySb100-x-yThe material of (a); wherein x and y are atomic number percentage respectively, x is more than 0 and less than 50, y is more than 0 and less than 50, and x + y is more than 0 and less than 60.
2. The Ti-Ga-Sb phase change material of claim 1, wherein the values of x, y are in the range of: x is more than or equal to 10 and less than or equal to y is less than or equal to 30.
3. A phase change memory using the Ti-Ga-Sb phase change material as claimed in claim 1 or 2 as a phase change memory material,
the Ti-Ga-Sb phase change material is a phase change film material with the thickness of 20-200 nm in the phase change memory.
4. The phase change memory of claim 3, wherein the phase change thin film material is Ti20Ga30Sb50A phase change film material.
5. The Ti-Ga-Sb phase-change material as claimed in any one of claims 1 to 4, wherein the Ti-Ga-Sb phase-change material can be prepared by a magnetron co-sputtering method, an electron beam evaporation method, a vapor deposition method or an atomic layer deposition method.
6. A preparation method of Ti-Ga-Sb phase-change material is used for preparing the phase-change film material in claim 4 or 5, which adopts a magnetron co-sputtering method to prepare the phase-change film material and comprises the following steps,
s1: selecting a sputtering substrate with a corresponding size according to the size of the phase-change film material, and cleaning the sputtering substrate;
s2: respectively preparing a Ga-Sb alloy target and a Ti simple substance target, and correspondingly arranging the positions of the two targets and the sputtering substrate;
s3: adopting high-purity inert gas as sputtering gas, and adjusting the flow and sputtering pressure of the sputtering gas;
s4: respectively setting the sputtering power of the Ga-Sb alloy target and the Ti simple substance target, preparing the phase-change thin film material by adopting a double-target co-sputtering method, and preparing the phase-change thin film material with different thicknesses by controlling the sputtering time.
7. The method of claim 6, wherein the Ga-Sb alloy target is Ga20Sb80Alloy target and Ga30Sb70Alloy target or Ga40Sb60An alloy target.
8. The method of preparing a Ti-Ga-Sb phase-change material according to claim 6 or 7, wherein in step S4, the sputtering power of the Ga-Sb alloy target is 30 to 40W, and the sputtering power of the Ti elemental target is 3 to 10W.
9. The method for preparing a Ti-Ga-Sb phase-change material according to any one of claims 6 to 8, wherein the sputtering time in the step S4 is 2 to 15 min.
10. The method for preparing a Ti-Ga-Sb phase-change material according to any one of claims 6 to 9, wherein before the step S4, the surface cleaning process of the Ga-Sb alloy target and the Ti elementary substance target is further carried out, and the method comprises the following steps:
and rotating the hollow substrate to target positions which are aligned with the Ga-Sb alloy target and the Ti simple substance target, opening the baffle plates of the two target positions, and pre-sputtering for 5-10 min.
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