A transition metal sulfide-doped single-element phase change memory material and its preparation method

Abstract

The present invention discloses a transition metal sulfide-doped single-element phase change memory material and a preparation method thereof, wherein the material is a MoS2-doped Sb thin film material, and the chemical structure of the thin film material is Sb x (MoS2) 100‑x , where 65at.%≤x≤85at.%, is obtained by dual-target sputtering of Sb single-element target and sulfur compound MoS2 target in a magnetron sputtering coating system. The advantage is that compared with GST phase change material, this phase change memory material has a higher crystallization temperature and a lower melting temperature, higher crystallization activation energy and ten-year data retention temperature, and greatly reduced resistance drift. In addition, the performance of single-element phase change Sb is successfully improved by doping with sulfur compounds, supporting the storage stability and reliability of phase change memory devices under long periods and high cycle numbers.

Description

Technical Field

[0001] The present invention belongs to the field of information storage phase change materials, and in particular relates to a transition metal sulfide-doped single-element Sb-MoS2 phase change storage material and a preparation method thereof. Background Art

[0002] Phase change memory (PCM) is a non-volatile memory that uses the properties of phase change materials to store data. Its core lies in the ability of phase change materials to reversibly change between amorphous and crystalline states under external stimulation, corresponding to different resistance states to achieve data storage. It is compatible with existing integrated circuit semiconductor processes (CMOS) and has a long cycle life (greater than 10 12 ), fast read / write speed (20 ns / 10 ns), and little impact from the environment can meet the needs of modern electronic devices for high stability, high storage density and high-speed data access. These advantages have jointly enabled phase change memory to occupy an important position in the storage field and provided strong support for the future development of storage technology.

[0003] Among the materials currently used in phase-change memory, Ge2Sb2Te5 (GST) is recognized by the industry as the most suitable storage material for PCM applications. Its crystallization process consists of two steps: at around 175°C, it changes from an amorphous state to a metastable face-centered cubic (fcc) structure, and then at around 280°C, it continues to change from fcc to a hexagonal close-packed (hex) structure. However, due to the ternary alloy system of GST, repeated phase change cycles easily induce component segregation, resulting in severe resistance drift (resistance drift coefficient). v =0.11), which shortens the device's service life and reduces its reliability, becoming the core bottleneck restricting breakthroughs in phase-change memory performance.

[0004] Among the innovations in phase-change material systems, single-element phase-change memory materials have demonstrated groundbreaking potential. Compared to traditional Ge-Sb-Te (GST) alloys, single-element Sb materials achieve superior physical properties by simplifying their composition: First, the single-atom system avoids the complexity of interfacial bonding in multi-element materials, significantly improving the orderliness of atomic arrangement and making the phase change process more controllable and repeatable. Second, the single-atom structure gives the material greater dimensional adaptability, maintaining stable phase change capabilities even at a thickness of 5nm, providing a physical basis for three-dimensional stacking of memory cells. These properties have enabled single-element phase-change memory to achieve orders of magnitude improvements in storage density, data retention, and durability. However, single-element Sb has extremely poor thermal stability and is prone to spontaneous crystallization at room temperature, severely inhibiting the development of single-element phase-change memory. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a transition metal sulfide-doped single-element phase change storage material and a preparation method thereof, which has a higher crystallization temperature and phase transition temperature, higher crystallization activation energy and ten-year data retention temperature, smaller resistance drift, and can achieve long-term stable storage.

[0006] The technical solution adopted by the present invention to solve the above technical problems is: a single-element phase change memory material doped with transition metal sulfide, which is a MoS2 doped Sb thin film material.

[0007] Preferably, the chemical structural formula of the film material is Sb x (MoS2) 100-x , where 65 at.%≤x≤85at.%.

[0008] Preferably, the chemical structural formula of the film material is Sb 79 (MoS2) 21 .

[0009] Preferably, the chemical structural formula of the film material is Sb 85 (MoS2) 15 .

[0010] Preferably, the chemical structural formula of the film material is Sb 70 (MoS2) 30 .

[0011] Preferably, the chemical structural formula of the film material is Sb 65 (MoS2) 35 .

[0012] The present invention also provides a method for preparing the above-mentioned MoS2-doped Sb thin film material, which comprises the following steps: obtaining the material by dual-target co-sputtering of a Sb single target and a MoS2 sulfur compound target in a magnetron sputtering coating system.

[0013] Furthermore, the specific steps are as follows: in a magnetron sputtering coating system, a single-element silicon wafer or a quartz wafer is used as a substrate, a Sb single-element target is installed in a magnetron DC sputtering target, a MoS2 target is installed in a magnetron RF sputtering target, and a sputtering chamber of the magnetron sputtering coating system is evacuated until the vacuum degree in the chamber reaches 9×10 -6 Pa, and then high-purity argon gas with a volume flow rate of 50 ml / min is introduced into the sputtering chamber until the pressure in the sputtering chamber reaches the ignition pressure of 0.3 Pa required for sputtering. Then, the sputtering power of the Sb single target is fixed at 30-50 W, and the sputtering power of the sulfide MoS2 target is adjusted to 22-40 W. The dual targets are co-sputtered at room temperature. After the sputtering thickness reaches 80 nm, the deposited Sb-MoS2 thin film material is obtained, and its chemical structure is Sb x(MoS2) 100-x , where 65 at.%≤x≤85 at.%.

[0014] Compared with the prior art, the advantages of the present invention are: the present invention provides a single element Sb-Mo-S thin film material doped with transition metal sulfide for phase change memory and its preparation method, the chemical structure of which is Sb x (MoS2) 100-x , where 65 at.%≤x≤85 at.%, and MoS2, as a transition metal sulfide semiconductor material, easily bonds with Sb elements to form an amorphous structure, thereby inhibiting Sb crystallization, improving the amorphous thermal stability and structural order of the material, enhancing the amorphous thermal stability of the film and maintaining the phase change ability. The preferred phase change material Sb 79 (MoS2) 21 Has a higher crystallization temperature ( T c ) is 232 ℃, the larger crystallization activation energy ( E a ) is 4.16V, strong ten-year data retention ( T 10-year ) is 148.6 ℃, and a lower resistance drift coefficient ν The resistance of the Sb phase-change memory film is 0.0004, which successfully solves the problem of poor thermal stability of the Sb single-element phase-change memory film. Compared with the common GST phase-change material, it has a higher crystallization temperature, higher crystallization activation energy, ten-year data retention temperature and ultra-low resistance drift coefficient. It is expected to improve the stability of the phase-change memory and reduce the power consumption of the device, and be used in long-cycle, high-cycle PCM. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The relationship curve of the resistance of the SSB0-SSB3 phase change film of the present invention as a function of temperature;

[0016] Figure 2 This is a ten-year data retention diagram of the SSB0-SSB2 phase change film of the present invention;

[0017] Figure 3 This is a resistance drift analysis diagram of the deposited SSB0-SSB3 of the present invention;

[0018] Figure 4 This is an X-ray diffraction analysis diagram of the SSB0 film of the present invention in a 150°C-350°C annealing state;

[0019] Figure 5 This is an X-ray diffraction analysis diagram of the SSB1 film of the present invention in a 150°C-350°C annealing state;

[0020] Figure 6This is an X-ray diffraction analysis diagram of the SSB2 film of the present invention in the annealing state of 150°C-350°C;

[0021] Figure 7 This is an X-ray diffraction analysis diagram of the SSB3 film of the present invention in the annealing state of 150℃-350℃. DETAILED DESCRIPTION

[0022] The present invention will be described in further detail below with reference to the accompanying drawings and embodiments.

[0023] 1. Specific Example: Single-element phase change memory material doped with transition metal sulfide, the material is MoS2 doped with Sb thin film material, the chemical structure of the thin film material is Sb x (MoS2) 100-x , where 65 at.%≤x≤85 at.%.

[0024] Example 1, Sb 85 (MoS2) 15 Preparation of phase change memory films.

[0025] In the magnetron sputtering coating system, a single-element silicon wafer or quartz wafer is used as the substrate, the Sb single-element target is installed in the magnetron DC sputtering target, and the MoS2 target is installed in the magnetron RF sputtering target. The sputtering chamber of the magnetron sputtering coating system is evacuated until the vacuum degree in the chamber reaches 9×10 -6 Pa, and then high-purity argon gas with a volume flow rate of 50 mL / min was introduced into the sputtering chamber until the pressure in the sputtering chamber reached the ignition pressure of 0.3 Pa required for sputtering. Then, the sputtering power of the Sb single target was fixed at 50 W, and the sputtering power of the sulfide MoS2 target was adjusted to 30 W. The dual targets were co-sputtered at room temperature. After the sputtering thickness reached 80 nm, the deposited Sb-MoS2 thin film material was obtained, and its chemical structure is Sb 85 (MoS2) 15 .

[0026] The prepared thin film material was subjected to in-situ resistance and resistance drift tests and XRD analysis, and the performance indicators of the thin film prepared in this embodiment were as follows: crystallization temperature T c The temperature is 185℃, the crystallization activation energy is 3.20eV, the ten-year data retention temperature is 107.4℃, and the resistance drift coefficient ν Compared with traditional GST materials, the same thickness of Sb 85 (MoS2) 15 The crystallization temperature is higher and the resistance drift coefficient is reduced by 2 orders of magnitude.

[0027] Example 2, Sb 79 (MoS2)21 Preparation of phase change memory films.

[0028] The same as the above embodiment 1, except that: during the sputtering process, the sputtering power of the Sb single target is controlled to be 30W, and the sputtering power of the MoS2 target is controlled to be 22W. The dual targets are co-sputtered at room temperature, and the sputtering thickness is 80 nm. The deposited preferred Sb / MoS2 phase change thin film material is obtained, and its chemical structure is Sb 79 (MoS2) 21 .

[0029] The prepared thin film material was subjected to in-situ resistance and resistance drift tests and XRD analysis, and the performance indicators of the thin film prepared in this embodiment were as follows: crystallization temperature T c The temperature is 232℃, the crystallization activation energy is 4.16eV, the ten-year data retention temperature is 148.6℃, and the resistance drift coefficient ν is 0.0004. Compared with Sb 85 (MoS2) 15 As the crystallization temperature of the material increases, the crystallization activation energy increases, the ten-year data storage temperature increases, and the resistance drift coefficient decreases significantly.

[0030] Example 3, Sb 70 (MoS2) 30 Preparation of phase change memory films.

[0031] The same as the above embodiment 1, except that: during the sputtering process, the sputtering power of the Sb single target is controlled to be 30W, the sputtering power of the MoS2 target is controlled to be 30W, and the dual targets are co-sputtered at room temperature. After the sputtering thickness is 80 nm, the deposited Sb-MoS2 phase change thin film material is obtained, and its chemical structure is Sb 70 (MoS2) 30 .

[0032] The prepared thin film material was subjected to in-situ resistance and resistance drift tests and XRD analysis, and the performance indicators of the thin film prepared in this embodiment were as follows: crystallization temperature T c The temperature is 252℃, the crystallization activation energy is 6.01eV, the ten-year data retention temperature is 194.2℃, and the resistance drift coefficient ν is 0.0021. Compared with Sb 79 (MoS2) 21 For materials, the crystallization temperature increases, the crystallization activation energy and the ten-year data retention temperature increase, but the resistance drift coefficient increases.

[0033] Example 4, Sb 65 (MoS2) 35 Preparation of phase change memory films.

[0034] The same as the above embodiment 1, except that: during the sputtering process, the sputtering power of the Sb single target is controlled to be 30W, and the sputtering power of the MoS2 target is controlled to be 40W. The dual targets are co-sputtered at room temperature. After the sputtering thickness is 80 nm, the deposited Sb-MoS2 phase change thin film material is obtained. Its chemical structure is Sb 65 (MoS2) 35 .

[0035] The prepared thin film material was subjected to in-situ resistance and resistance drift tests and XRD analysis, and the performance indicators of the thin film prepared in this embodiment were as follows: crystallization temperature T c At 267°C, the resistance drift coefficient ν is 0.0046. Compared with Sb 79 (MoS2) 21 The material has a slightly increased crystallization temperature and a higher resistance drift coefficient.

[0036] Control experiment, preparation of Ge2Sb2Te5 phase change memory film.

[0037] The method is basically the same as Example 1, except that the alloy Ge2Sb2Te5 target is installed in a magnetron RF sputtering target, the sputtering power is set to 30W, and a single target sputtering coating is performed at room temperature. After the sputtering thickness reaches 80 nm, a pure Ge2Sb2Te5 phase change memory film is obtained. The prepared film is subjected to in-situ resistance performance testing, and the performance indicators of the film prepared in the control experiment are as follows: crystallization temperature ( T c ) is 176 ℃, the crystallization activation energy is 2.98 eV, the ten-year data retention temperature is 89 ℃, and the resistance drift coefficient is 0.11.

[0038] The target sputtering power, Sb, MoS2 content and related thermal parameters of the above different embodiments are shown in Table 1.

[0039] Table 1 Composition and related thermal parameters of 80 nm Sb-Mo-S phase change thin films prepared under different conditions

[0040]

[0041] 2. Experimental results analysis: The results of different embodiments in the specific embodiments are analyzed as follows.

[0042] Figure 1 The relationship between the resistance and temperature of SSB0-SSB3 films tested at a heating rate of 30℃ / min is given. We can see that the resistance of all films decreases gradually with increasing temperature. 85 (MoS2)15 The film has a large resistance change at about 185℃, and phase change crystallization occurs. As the content of MoS2 increases, the crystallization temperature of the film gradually rises. 79 (MoS2) 21 、Sb 70 (MoS2) 30 Thin film and Sb 65 (MoS2) 35 The crystallization temperatures of the films are ~232, ~252 and ~267℃, respectively, showing a gradually increasing trend. Compared with GST material films and pure Sb films, they have better phase change characteristics and thermal stability.

[0043] Figure 2 The ten-year data retention diagram of SSB0-SSB2 phase change film is given. It can be found that Sb 85 (MoS2) 15 The crystallization activation energy of the film is 3.20eV, and the ten-year data retention temperature is 107.4℃. 79 (MoS2) 21 The crystallization activation energy of the film is 4.16eV, and the ten-year data retention temperature is 148.6°C. 70 (MoS2) 30 The crystallization activation energy of the film is 6.01eV, and the ten-year data retention temperature is 194.2°C. x (MoS2) 100-x The film crystallization activation energy and ten-year data retention temperature gradually increase with the increase of MoS2 content, and the film stability gradually increases.

[0044] Figure 3 The resistance drift analysis of SSB0-SSB3 thin films at room temperature is given. It can be found that Sb 85 (MoS2) 15 The resistance drift coefficient of the film is 0.0024, Sb 79 (MoS2) 21 The resistance drift coefficient of the film is 0.0004, Sb 70 (MoS2) 30 The resistance drift coefficient of the film is 0.0021, Sb 65 (MoS2) 35 The resistance drift coefficient of the film is 0.0046. The resistance drift decreases first and then increases with the increase of MoS2 content. The preferred material Sb 79 (MoS2) 21 Compared with GST materials, it is improved by 3 orders of magnitude.

[0045] Figure 4The X-ray diffraction analysis of SSB0 film annealed at 150℃-350℃ is given. It can be found that Sb 85 (MoS2) 15 The Sb(012) and Sb(110) phases begin to precipitate in the film when annealed at 150°C, indicating that the material begins to undergo a phase transition at 150°C. The Sb phase peak increases with increasing temperature, indicating that the material's crystallinity gradually increases and its structure tends to be stable.

[0046] Figure 5 The X-ray diffraction analysis of SSB1 film annealed at 150℃-350℃ is given. It can be found that Sb 79 (MoS2) 21 The film precipitates Sb(012) crystal phase when annealed at 200℃, and Sb(110) crystal phase when annealed at 250℃, indicating that the material begins to undergo phase transition at 200℃. 85 (MoS2) 15 As the film's phase transition temperature increases, the isothermal crystallization peak decreases, indicating that Sb crystallization is somewhat suppressed. The Sb crystal phase peak rises with increasing temperature, indicating that the material's crystallinity gradually increases and its structure stabilizes.

[0047] Figure 6 The X-ray diffraction analysis of SSB2 film annealed at 150℃-350℃ is given. It can be found that Sb 70 (MoS2) 30 The Sb(012) crystal phase precipitated in the film under 250℃ annealing condition, indicating that the material began to undergo phase transition at 250℃. 79 (MoS2) 21 As the film phase transition temperature increases, the Sb crystal peak is lower at the same temperature and no Sb(110) crystal phase precipitates, indicating that MoS2 inhibits the crystallization of Sb. The Sb crystal phase peak increases with increasing temperature, indicating that the material's crystallinity gradually increases and the structure tends to be stable.

[0048] Figure 7 The X-ray diffraction analysis of SSB2 film annealed at 150℃-350℃ is given. It can be found that Sb 65 (MoS2) 35 The Sb(012) crystal phase precipitated in the film under 250℃ annealing condition, indicating that the material began to undergo phase transition at 250℃. 70 (MoS2) 30 The Sb crystal peak is lower at constant temperature, further indicating that MoS2 inhibits the crystallization of Sb. The Sb crystal phase peak increases with increasing temperature, indicating that the material's crystallinity gradually increases and the structure tends to be stable.

[0049] In summary, the crystallization temperature of a transition metal sulfide-doped single-element Sb-MoS2 phase change memory material prepared by the present invention is increased to above 232°C, and the resistance drift coefficient reaches 0.0004, which solves the problems of poor thermal stability and severe resistance drift of traditional phase change materials. Compared with traditional GST phase change materials, preferably Sb 79 (MoS2) 21 The film has a higher crystallization temperature and phase transition temperature, higher activation energy and ten-year data retention temperature, and smaller resistance drift, which improves storage stability and reliability under long periods and high cycle numbers.

[0050] The above description is not intended to limit the present invention, and the present invention is not limited to the above examples. Any changes, modifications, additions, or substitutions made by a person skilled in the art within the spirit and scope of the present invention shall also fall within the scope of protection of the present invention, and the scope of protection of the present invention shall be subject to the claims.

Claims

1. A transition metal sulfide-doped single-element phase change memory material, characterized in that: The material is a MoS2 doped Sb thin film material, the chemical structure of which is Sb x (MoS2) 100-x , wherein 65 at.%≤x≤85 at.%, and the MoS2 doped Sb thin film material is obtained by dual-target sputtering of a Sb single-substance target and a sulfur compound MoS2 target in a magnetron sputtering coating system.

2. The transition metal sulfide-doped single-element phase change memory material according to claim 1, characterized in that: The chemical structural formula of the film material is Sb 79 (MoS2) 21 .

3. The transition metal sulfide-doped single-element phase change memory material according to claim 1, characterized in that: The chemical structural formula of the film material is Sb 85 (MoS2) 15 .

4. The transition metal sulfide-doped single-element phase change memory material according to claim 1, characterized in that: The chemical structural formula of the film material is Sb 70 (MoS2) 30 .

5. The transition metal sulfide-doped single-element phase change memory material according to claim 1, characterized in that: The chemical structural formula of the film material is Sb 65 (MoS2) 35 .

6. The method for preparing a transition metal sulfide-doped single-element phase change memory material according to any one of claims 1 to 5, characterized in that The specific steps are as follows: In the magnetron sputtering coating system, a single-element silicon wafer or quartz wafer is used as the substrate, the Sb single-element target is installed in the magnetron DC sputtering target, the MoS2 target is installed in the magnetron RF sputtering target, and the sputtering chamber of the magnetron sputtering coating system is evacuated until the vacuum degree in the chamber reaches 9×10 -6 Pa, and then high-purity argon gas with a volume flow rate of 50 ml / min is introduced into the sputtering chamber until the pressure in the sputtering chamber reaches the ignition pressure of 0.3 Pa required for sputtering. Then, the sputtering power of the Sb single target is fixed at 30-50 W, and the sputtering power of the sulfide MoS2 target is adjusted to 22-40 W. The dual targets are co-sputtered at room temperature. After the sputtering thickness reaches 80 nm, the deposited Sb-MoS2 thin film material is obtained, and its chemical structure is Sb x (MoS2) 100-x , where 65 at.%≤x≤85 at.%.

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