Phase change memory and preparation method thereof

Abstract

An embodiment of the present disclosure provides a phase change memory and a preparation method thereof. The phase change memory includes: a first conductive line, a phase change memory unit, and a second conductive line stacked in sequence along a first direction, the first conductive line extending along a second direction, and the second conductive line extending along a third direction, the first direction, the second direction, and the third direction being perpendicular to each other; the phase change memory unit includes a phase change memory layer, the composition material of the phase change memory layer includes A-Ga-Sb-Te material, wherein the content of A is a mol%, and 0<a≤20, the content of Ga is b mol%, and 0<b≤50, the content of Sb is c mol%, and 20≤c≤90, and the content of Te is (100-a-b-c) mol%; the A element is used to regulate the cycle capacity of the phase change memory unit.

Description

Technical Field

[0001] The present disclosure relates to the field of semiconductor technology, and in particular to a phase change memory and a preparation method thereof. Background Art

[0002] In the existing storage hierarchy, there's a gap in storage speed and capacity between dynamic random access memory (DRAM) and non-volatile memory (Flash), limiting further advancements in computing power. To address this, storage-class memory (SCM), a type of memory with storage speed and capacity intermediate between DRAM and Flash, has been proposed. Phase-change memory (PCM) is considered the most promising solution for SCM, and through the selection of PCM materials, a balance between performance and cost can be achieved. Summary of the Invention

[0003] According to a first aspect of the present disclosure, a phase change memory is provided, comprising:

[0004] A first conductive line, a phase-change memory unit, and a second conductive line are sequentially stacked along a first direction, the first conductive line extends along a second direction, the second conductive line extends along a third direction, and the first direction, the second direction, and the third direction are perpendicular to each other;

[0005] The phase change memory unit includes a phase change memory layer, and the composition material of the phase change memory layer includes A-Ga-Sb-Te material, wherein the content of A is a mol%, and 0<a≤20, the content of Ga is b mol%, and 0<b≤50, the content of Sb is c mol%, and 20≤c≤90, and the content of Te is (100-abc) mol%; the A element is used to regulate the cycle capacity of the phase change memory unit.

[0006] In some embodiments, the A element includes at least one of carbon, nitrogen, oxygen, or silicon.

[0007] In some embodiments, the phase change memory layer is composed of a material further comprising Ti element; wherein the content of Ti is d mol %, and 0<d≤20, and the content of Te is (100-abcd) mol %.

[0008] In some embodiments, the Ga content satisfies: 5 mol%≤b mol%≤10 mol%.

[0009] In some embodiments, the phase-change memory unit further includes two electrode layers, which are arranged on opposite sides of the phase-change memory layer along the first direction, and the two electrode layers are in contact with the phase-change memory layer;

[0010] The adhesion between the phase change memory layer and the electrode layer is characterized by an energy release rate, and the energy release rate is greater than or equal to 0.7 J / m 2 .

[0011] In some embodiments, the electrode layer is made of tungsten.

[0012] According to a second aspect of the present disclosure, a method for preparing a phase change memory is provided, comprising:

[0013] A first conductive line layer and a memory cell material layer are stacked and formed along a first direction; wherein the memory cell material layer includes a phase change memory material layer, and the material of the phase change memory material layer includes an A-Ga-Sb-Te material, wherein the content of A is a mol%, and 0<a≤20, the content of Ga is b mol%, and 0<b≤50, the content of Sb is c mol%, and 20≤c≤90, and the content of Te is (100-abc) mol%. The first direction is perpendicular to the plane where the first conductive line layer is located.

[0014] forming a plurality of first isolation structures penetrating the first conductive line layer and the memory cell material layer; wherein each first isolation structure extends along the second direction, and the plurality of first isolation structures are arranged in parallel along a third direction; the plurality of first isolation structures divide the first conductive line layer into a plurality of first conductive lines; and the third direction and the second direction are perpendicular to the first direction.

[0015] forming a second conductive line layer covering the first isolation structure and the memory cell material layer;

[0016] A plurality of second isolation structures are formed that penetrate the second conductive line layer and the storage unit material layer; wherein each second isolation structure extends along a third direction, and the plurality of second isolation structures are arranged in parallel along the second direction; the plurality of second isolation structures divide the second conductive line layer into a plurality of second conductive lines; the plurality of first isolation structures and the plurality of second isolation structures divide the storage unit material layer into a plurality of mutually independent phase change memory units, each of the phase change memory units includes a phase change memory layer, and the A element in the phase change memory layer is used to regulate the cyclability of the phase change memory unit.

[0017] In some embodiments, the phase-change memory material layer further comprises Ti element; wherein the content of Ti is d mol %, and 0<d≤20, and the content of Te is (100-abcd) mol %.

[0018] In some embodiments, the Ga content satisfies: 5 mol%≤b mol%≤10 mol%.

[0019] In some embodiments, the memory cell material layer further includes two electrode material layers;

[0020] The forming of the memory cell material layer includes:

[0021] A first electrode material layer, the phase change memory material layer, and a second electrode material layer are stacked along a first direction; wherein both the electrode material layers are in contact with the phase change memory material layer; and the adhesion between the phase change memory material layer and the electrode material layer is characterized by an energy release rate, and the energy release rate is greater than or equal to 0.7 J / m 2 ;

[0022] The forming of a plurality of first isolation structures penetrating the memory cell material layer comprises:

[0023] forming a plurality of first isolation structures penetrating the first electrode material layer, the phase-change memory material layer, and the second electrode material layer;

[0024] The forming of a plurality of second isolation structures penetrating the memory cell material layer comprises:

[0025] A plurality of second isolation structures are formed penetrating the first electrode material layer, the phase-change memory material layer, and the second electrode material layer.

[0026] The phase change memory provided by the present disclosure has a phase change memory layer whose constituent material includes an A-Ga-Sb-Te material, wherein the content of A is a mol%, and 0<a≤20, the content of Ga is b mol%, and 0<b≤50, the content of Sb is c mol%, and 20≤c≤90, and the content of Te is (100-abc) mol%; the A element is used to regulate the cyclic capacity of the phase change memory unit. In the present disclosure, the Ga element can improve the adhesion between the phase change memory layer and the electrode layer, and increase the hardness of the phase change memory layer, thereby reducing the probability of peeling between the phase change memory layer and the electrode layer, reducing production risks, and enabling the A-Ga-Sb-Te material provided by the present disclosure to be applied to mass-produced phase change memories. Furthermore, the A element can regulate the cyclic capacity of the phase change memory unit, so that a phase change memory with a cyclic capacity that meets the requirements can be prepared by adjusting the content of the A element according to actual use requirements. In summary, the present disclosure provides a phase change memory material that can be applied to mass-produced phase change memories, namely, A-Ga-Sb-Te material. The material composition can be flexibly and controllably adjusted, and the proportion of each element can be adjusted within the above-mentioned content range according to performance and cost requirements, thereby obtaining a phase change memory that meets the requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1a and Figure 1b A comparison chart of peeling results of two phase-change memory layers provided in an embodiment of the present disclosure;

[0028] Figure 2 A schematic diagram of the structure of a phase change memory provided by an embodiment of the present disclosure;

[0029] Figure 3 for Figure 2 A partial cross-sectional view of the phase change memory shown;

[0030] Figure 4 A schematic diagram of a sample structure for adhesion testing of a phase change memory material layer and a tungsten layer provided in an embodiment of the present disclosure;

[0031] Figure 5 for Figure 4 Energy release rates of the different specimens shown;

[0032] Figure 6 A schematic flow chart of a method for preparing a phase change memory provided in an embodiment of the present disclosure. DETAILED DESCRIPTION

[0033] The technical solution of the present disclosure is further elaborated in detail below with reference to the accompanying drawings and specific embodiments.

[0034] In the description of the present disclosure, it should be understood that the terms "length", "width", "depth", "up", "down", "outside", etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present disclosure and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present disclosure.

[0035] The basic principle of phase-change memory (PCM) is that a high-value, short-duration (i.e., high and narrow) electric pulse is applied to a PCM cell. Due to Joule heating and other factors, a portion of the initially crystalline PCM layer melts due to temperatures exceeding its melting point. After the pulse is interrupted, the melted portion rapidly cools, reverting to an amorphous state with low atomic order, completing the transition from low resistance to high resistance. This is the erase (reset) process. The melted portion during this process is called the programming volume. If a low-value, long-duration (i.e., low and wide) electric pulse is applied, causing the temperature within the programming volume to rise above the crystallization temperature but below the melting temperature, and the duration is sufficient for the amorphous structure within the programming volume to crystallize, a low-resistance state is achieved. This is the write (set) process. The read process of PCM involves applying a low, narrow electric pulse to the PCM cell, bringing the PCM layer below its crystallization temperature, and then measuring the cell's resistance.

[0036] Phase-change memory materials, the storage medium of phase-change memory, have a direct impact on the device's performance. Typically, the performance of phase-change memory is measured by metrics such as write speed, data retention, and on / off ratio. Therefore, performance research on phase-change memory materials includes studies on parameters such as crystallization rate, crystallization temperature, amorphous structure stability, thermal stability, and resistance window (i.e., the ratio of the resistivity of the amorphous and crystalline states).

[0037] For phase-change memory, write operations typically take longer than erase operations, becoming a key factor limiting its high-speed operation. This write time is related to the crystallization rate of the phase-change memory material. A faster crystallization rate shortens the write time, and the phase-change memory's operating speed increases.

[0038] The data retention of phase-change memory (PCM) is primarily determined by the amorphous structural stability and thermal stability of the PCM material. The better the amorphous structural and thermal stability, the better the data retention and the longer the data storage lifespan. To achieve these high amorphous structural and thermal stability, the PCM material must have a high crystallization temperature and a large crystallization activation energy.

[0039] The on / off ratio of phase-change memory is determined by the resistance window of the phase-change memory material. This resistance window refers to the resistivity difference between the amorphous and crystalline states. A larger resistivity difference between the amorphous and crystalline states creates a larger resistance window, ensuring a larger on / off ratio and enabling accurate and fast data reads.

[0040] The most mature phase-change memory material is the germanium-antimony-tellurium (Ge-Sb-Te, GST) ternary compound. Doping modification based on the Ge-Sb-Te compound is a relatively effective modification method, capable of meeting the application requirements of most devices. However, as the price of germanium (Ge) rises, the price of phase-change memory materials also rises, which in turn leads to an increase in the price of phase-change memory.

[0041] Antimony-tellurium (Sb-Te) compounds have a fast crystallization rate, making them the preferred phase-change memory material for achieving high-speed operation in phase-change memories (PCMs), and they also offer a price advantage. However, Sb-Te compounds often suffer from low crystallization temperatures, poor amorphous structure stability, and insufficient thermal stability. Furthermore, when applied to PCMs, the PCM layer containing Sb-Te compounds easily peels off from the electrode layer, causing damage to the PCM cell. This severely limits the application of Sb-Te compounds in commercial PCMs.

[0042] Figure 1a and Figure 1b A comparison of the peeling results of the two phase change storage layers. Figure 1a and Figure 1b The phase change memory layer and the tungsten layer 40 are sequentially deposited on the substrate 10, and multiple phase change memory cells are formed by etching, wherein: Figure 1a The phase change storage layer is the commonly used GST layer. Figure 1b The phase change memory layer is a Sb-Te layer. An interconnection structure is provided in the substrate 10, and the interconnection structure is used to contact and connect with the GST layer or the Sb-Te layer.

[0043] An electric pulse is applied to the tungsten layer 40 using the electrode 90. Under the action of the electric pulse, the phase change memory layer undergoes a phase change, and it is observed whether the phase change memory layer and the tungsten layer will peel off. Figure 1a As shown, the GST layer and the tungsten layer 40 do not peel off; Figure 1b As shown, the Sb—Te layer and the tungsten layer 40 are peeled off over a large area, exposing the substrate 10 .

[0044] Here, the grayscale of the substrate 10 exposed after the Sb-Te layer and the tungsten layer 40 are peeled off is different from that of the substrate 10 not covered by the Sb-Te layer and the tungsten layer 40. This is because the substrate 10 not covered by the Sb-Te layer and the tungsten layer 40 has a different reflection effect on light after etching.

[0045] Depend on Figure 1a and Figure 1b It can be seen that if the Sb-Te layer is applied to phase change memory, the Sb-Te layer will peel off during the programming operation, causing damage to the phase change memory cell. Therefore, Sb-Te material is difficult to apply to mass-produced phase change memory.

[0046] In view of this, an embodiment of the present disclosure provides a phase change memory, in which a phase change storage material is obtained by doping and modification of a Sb—Te compound. Figure 2 A schematic diagram of the structure of a phase change memory provided by an embodiment of the present disclosure is shown. Figure 3 for Figure 2 A partial cross-sectional view of a phase change memory is shown. Figure 2 and Figure 3 As shown, the phase change memory includes: a first conductive line 100, a phase change memory unit 200, and a second conductive line 300 stacked in sequence along a first direction, the first conductive line 100 extends along a second direction, and the second conductive line 300 extends along a third direction, and the first direction, the second direction, and the third direction are perpendicular to each other;

[0047] The phase change memory unit 200 includes a phase change memory layer 201, and the composition material of the phase change memory layer 201 includes A-Ga-Sb-Te material, wherein the content of A is a mol%, and 0<a≤20, the content of Ga is b mol%, and 0<b≤50, the content of Sb is c mol%, and 20≤c≤90, and the content of Te is (100-abc) mol%. The A element is used to regulate the cyclability of the phase change memory unit.

[0048] Here, the first direction is defined as the Z direction, the second direction is defined as the X direction, and the third direction is defined as the Y direction. The first conductive line 100 and the second conductive line 300 are perpendicular to each other, and the phase-change memory unit 200 is located at the intersection of the first conductive line 100 and the second conductive line 300. For example, the first conductive line 100 can be a bit line, and the second conductive line 300 can be a word line. Alternatively, the first conductive line 100 can be a word line, and the second conductive line 300 can be a bit line.

[0049] See further Figure 3 The phase change memory unit 200 further includes a bottom electrode 202, a gating layer 203, an intermediate electrode 204 and a top electrode 205 sequentially arranged on the first conductive line along the first direction, wherein the phase change memory layer 201 is located between the intermediate electrode 204 and the top electrode 205.

[0050] In some embodiments, the phase change memory unit 200 may also include a bottom electrode 202 , a phase change memory layer 201 , an intermediate electrode 204 , a gating layer 203 and a top electrode 205 sequentially disposed on the first conductive line 100 along the first direction.

[0051] Intermediate electrode 204 is generally considered a heating electrode for phase-change memory layer 201. When an electrical pulse flows through phase-change memory cell 200, it generates Joule heat, raising the temperature of phase-change memory layer 201 and achieving a transition between the crystalline and amorphous states. The heating electrode not only affects the electrical pulses used in write and erase operations, but the adhesion between the heating electrode and phase-change memory layer 201 also directly impacts the lifespan of the phase-change memory.

[0052] It is understood that during the write and erase cycles, the phase-change memory material repeatedly transforms between the amorphous state and the crystalline state. Due to the density difference between the crystalline and amorphous states, the volume of the phase-change memory layer 201 changes during the cycle. If the adhesion between the phase-change memory layer 201 and the heater electrode is poor, the phase-change memory layer 201 and the heater electrode may peel off, resulting in a sharp increase in resistance at the interface between the phase-change memory layer 201 and the heater electrode, causing erase anomalies and device failure. In addition, in some embodiments, when a metal electrode is deposited on the phase-change memory layer 201, the stress applied to the phase-change memory layer 201 by the metal electrode may also cause peeling between the phase-change memory layer and the electrode in contact therewith.

[0053] The material of the phase change memory layer 201 provided in the embodiment of the present disclosure includes gallium (Ga), antimony (Sb), tellurium (Te) and A, wherein the content of A is a mol%, and 0<a≤20, the content of Ga is b mol%, and 0<b≤50, the content of Sb is c mol%, and 20≤c≤90, and the content of Te is (100-abc) mol%. The composition of the phase change memory layer 201 is written in the form of a chemical formula, which can be expressed as A a Ga b Sb c Te (100-a-b-c) , where a satisfies 0<a≤20, b satisfies 0<b≤50, and c satisfies 20≤c≤90.

[0054] The content of Te element is (100-abc) mol%, which can be understood as: when the total amount of A-Ga-Sb-Te material is 100 moles (mol), except for a mole of A element, b moles of Ga element and c moles of Sb element, the rest are Te elements.

[0055] For example, the content of Te element is e mol%, and satisfies 0<e≤80.

[0056] In the phase-change memory layer disclosed herein, the Ga element can improve the adhesion between the phase-change memory layer and the electrode layer, reducing the probability of peeling between the phase-change memory layer and the electrode layer. Furthermore, the Ga element can give the phase-change memory layer a higher hardness, so that when the electrode layer deposited on the phase-change memory layer applies stress to the phase-change memory layer, the phase-change memory layer deforms less and will not tear, thereby reducing the probability of partial peeling between the phase-change memory layer and the electrode layer, improving the reliability of the phase-change memory and extending the service life of the phase-change memory. Furthermore, the Ga element can also increase the crystallization temperature of the phase-change memory layer.

[0057] However, the gallium content should not be too high. According to the research disclosed in this paper, the solid solubility of Ga in Sb-Te materials is low. If the Ga content exceeds the above range, the tendency of the Ga-Sb-Te material to separate will increase significantly, producing a large amount of Sb phase.

[0058] In the phase-change memory layer provided by this disclosure, element A can regulate the cyclability of the phase-change memory cell. When element A is added to the Ga-Sb-Te material, the resulting phase-change memory cell made from the A-Ga-Sb-Te material exhibits significantly improved cyclability compared to a phase-change memory cell made from the Ga-Sb-Te material.

[0059] In some embodiments, the A element improves the cycle capability of the phase change memory cell by suppressing the appearance of the Sb phase. For example, the A element includes at least one of carbon (C), nitrogen (N), oxygen (O), or silicon (Si).

[0060] Atoms A can form bonds with Ga, Sb, and Te atoms, reducing the probability of Sb atoms bonding with each other. This reduces the probability of the Sb phase appearing in the phase-change memory layer when the A content is within the aforementioned range. Furthermore, even if the Sb phase does appear, A can be enriched at the grain boundaries of the Sb phase, inhibiting its grain growth and thus controlling its content within a certain range.

[0061] According to the research disclosed in this paper, the Sb phase has a low crystallization temperature and good thermal stability in the crystalline state, but poor stability in the amorphous state. This means that once the Sb phase precipitates in the phase-change memory layer, it is difficult for the Sb phase to transform into the amorphous state and thus does not participate in the reversible phase transition process. This results in a smaller resistance difference between the high-resistance and low-resistance states of the phase-change memory layer, that is, a smaller resistance window.

[0062] The cyclability of a phase-change memory can be characterized by the number of cycles it can undergo while meeting the resistance window requirement. In the present disclosure, by adding the aforementioned content of element A, the probability of the Sb phase appearing in the phase-change memory layer can be reduced. Once the Sb phase appears, its grain growth can be suppressed, and the Sb phase content can be controlled within a certain range. This ensures that the resistance window of the phase-change memory layer remains within the required range over a greater number of phase-change cycles, thereby improving the cyclability of the phase-change memory.

[0063] In some embodiments, element A can significantly increase the crystallization temperature of the phase change memory layer, thereby improving the thermal stability of the phase change memory layer. Element A can also improve the stability of the amorphous structure of the phase change memory layer, thereby increasing the tolerance of the phase change memory layer to external stress and ambient temperature, thereby improving the data retention capability of the phase change memory.

[0064] In some embodiments, element A can form bonds with Ga, Sb, and Te, strengthening the interaction between adjacent layers and thereby increasing the hardness of the phase-change memory layer. Furthermore, element A can form bonds with W, thereby strengthening the interaction between the A-Ga-Sb-Te material and W, thereby appropriately improving the adhesion between the phase-change memory layer and the tungsten electrode layer.

[0065] Here, the content of element A should not be too high. According to the research disclosed in this disclosure, adding element A to Ga-Sb-Te can improve the stability of the amorphous structure. If the content of element A exceeds the above range, the resistance of the phase change memory layer will remain at a certain resistance value, and high and low resistance states cannot be achieved, that is, reversible phase transition cannot be achieved.

[0066] The present disclosure provides a phase change memory material, namely, an A-Ga-Sb-Te material, that can be applied to mass-produced phase change memories. The phase change memory layer and electrode layer prepared with this material have a low probability of peeling off, which can reduce production risks. In addition, the material composition can be flexibly and controllably adjusted. By adjusting the proportion of each element within the above-mentioned content range, different performance and cost requirements can be met. For example, improvements in operating speed and cycle capacity can be achieved simultaneously, thereby expanding the range of phase change memory materials that can be used in large-scale production.

[0067] For example, in some embodiments, when the content of element A is high, the phase-change memory layer has a higher crystallization temperature, better thermal stability and amorphous structure stability, and thus the phase-change memory has better data retention and cycle capability.

[0068] In some embodiments, when the content of element A is low, the phase-change memory layer has a faster erase and write speed.

[0069] In some embodiments, when the Ga content is high, the adhesion between the phase change memory layer and the electrode layer is high, and the hardness of the phase change memory layer is high, so the probability of peeling off between the phase change memory layer and the electrode layer is reduced. This can reduce production risks and reduce the probability of peeling off between the phase change memory layer and the electrode layer during repeated phase changes of the phase change memory, thereby improving the cycle capacity of the phase change memory.

[0070] In some embodiments, when the Ga content is low, the resistance window of the phase change memory layer is larger, and the phase change memory has a larger switching ratio, which can improve the speed and accuracy of data reading.

[0071] In some embodiments, the chemical formula of the material of the phase change memory layer 201 is ClGa 49 Sb 20 Te 30 、N1Ga 50 Sb 30 Te 19 、O5Ga 40 Sb 40 Te 15 、Si 10 Ga 30 Sb 50 Te 10 、C 15 Ga 20 Sb 60 Te5、N 20 Ga 10 Sb 69 Te1、O1Ga1Sb 80 Te 18 、Si1Ga8Sb 90 Te1, C 10 Ga 10 Sb 20 Te 60 、N1Ga1Sb 20 Te 78 One of them.

[0072] The following combination Figures 4 to 6 The experimental results analyze the adhesion and hardness advantages of A-Ga-Sb-Te materials.

[0073] Figure 4 Schematic diagram of the sample structure for adhesion test of the phase change memory material layer and the tungsten layer provided in an embodiment of the present disclosure. Figure 5 for Figure 4 Energy release rates of different specimens are shown.

[0074] In the adhesion test employed in this disclosure, a phase-change memory material layer and an electrode material layer are sequentially deposited on a substrate. A tensile force is applied to the electrode material layer, causing the two layers to separate. The energy release rate during the separation process is then measured to measure the adhesion between the two layers. For example, a silicon wafer can be attached to the topmost electrode material layer and pulled upward, thereby applying an upward tensile force to the electrode material layer, thereby separating the two layers.

[0075] Energy release rate Gc is a parameter commonly used in the field to measure the adhesion between film layers. The energy release rate can quantitatively characterize the adhesion between different film layers. The energy release rate has the dimension of J / m 2 , which indicates how much energy is required per unit area to break the adhesion between film layers. The greater the energy release rate, the better the adhesion.

[0076] Figure 4 and Figure 5 The adhesion test results shown here use tungsten as the electrode material. In other adhesion tests, amorphous carbon can also be used as the electrode material.

[0077] like Figure 4 As shown, sample No. 1 (#01) is a first tungsten layer 20, an Sb-Te layer 30 and a second tungsten layer 40 deposited in sequence on the substrate 10. Sample No. 2 (#02) is a Sb-Te layer 30 and a tungsten layer 40 deposited in sequence on the substrate 10. Sample No. 3 (#3) is a Ga-Sb layer 50 and a tungsten layer 60 deposited on the substrate 10.

[0078] Here, the thickness of the tungsten layer 40 in Sample No. 1 and Sample No. 2 is the same, and the thickness of the tungsten layer 60 in Sample No. 3 is greater than that of the tungsten layer in Sample No. 1 and Sample No. 2. For example, the thickness of the tungsten layer in Sample No. 3 is greater than the maximum tungsten layer thickness used in mass-produced phase change memories.

[0079] Here, the Sb-Te layer 30 and the Ga-Sb layer 50 are phase change memory material layers. The Sb-Te layer 30 is made of SbTe (i.e., the atomic ratio of Sb to Te is 1:1), and the Ga-Sb layer 50 is made of Ga. 50 Sb 50 In some other adhesion tests, the material of the Ga-Sb layer 50 of sample No. 3 can also be Ga 40 Sb 60 、Ga 30 Sb 70 、Ga 20 Sb 80 、Ga 10 Sb 90 One of them.

[0080] Here, the material of the substrate 10 includes an oxide, such as silicon oxide. In some embodiments, the silicon oxide is formed using a chemical vapor deposition (CVD) process. The silicon oxide has good adhesion to the phase change memory material layer or the electrode material layer 20, ensuring that during the adhesion test, delamination does not occur between the substrate 10 and the phase change memory material layer or the electrode material layer 20, but rather between the phase change memory material layer and the electrode material layer 20. This allows the energy release rate to be determined when the phase change memory material layer and the electrode material layer 20 are delaminated.

[0081] When testing the adhesion of specimens 1, 2, and 3, Figure 4 and Figure 5 As shown in FIG1 , sample No. 1, sample No. 2, and sample No. 3 peeled off from the interface corresponding to the dotted line between the two scissors symbols. Specifically, sample No. 1 peeled off from the interface between the Sb-Te layer 30 and the tungsten layer 40, and the energy release rate was 0.702 J / m 2 Sample No. 2 peeled off not only from the interface between the Sb-Te layer 30 and the tungsten layer 40, but also from the interface between the Sb-Te layer 30 and the substrate 10, and the energy release rate was only 0.35 J / m 2 In actual operation, a slight external force can be applied to sample No. 2 to peel off the tungsten layer 40 from the Sb-Te layer 30, and the Sb-Te layer 30 is also peeled off from the substrate 10, indicating that the adhesion between the Sb-Te layer 30 and the tungsten layer 40 is extremely poor, and the adhesion between the Sb-Te layer 30 and the substrate 10 is also extremely poor.

[0082] Sample No. 3 peeled off from the interface between the Ga-Sb layer 50 and the tungsten layer 60, and the energy release rate was 1.34 J / m 2 , much larger than 0.35J / m of sample No. 2 2 and 0.702J / m of sample No. 1 2 , indicating that the adhesion between the Ga—Sb layer 50 and the tungsten layer 60 is much better than the adhesion between the Sb—Te layer 30 and the tungsten layer 40 .

[0083] Furthermore, the thickness of the tungsten layer 60 in sample No. 3 is greater than the thickness of the tungsten layer 40 in sample No. 1 and sample No. 2. It is understandable that tungsten layers deposited by physical vapor deposition (PVD) often have strong compressive stress, which is equivalent to applying a large external force to the phase change memory material layer. And as the thickness of the tungsten layer increases, the external force on the phase change memory material layer gradually increases, which will aggravate the tendency of the phase change memory material layer to peel off. However, when the tungsten layer 60 is thicker, sample No. 3 achieves a greater energy release rate than sample No. 2, further indicating that the adhesion between the Ga-Sb layer 50 and the tungsten layer is much better than the adhesion between the Sb-Te layer 30 and the tungsten layer.

[0084] also, Figure 5In the figure, the dotted line L parallel to the horizontal axis represents the energy release rate of the GST layer and the tungsten layer peeling. Figure 5 As shown, the energy release rate of sample No. 3 is greater than the energy release rate of the GST layer, indicating that the adhesion between the Ga—Sb layer 50 and the tungsten layer is greater than the adhesion between the GST layer and the tungsten layer.

[0085] In some other embodiments of the present disclosure, the element content of the Ga-Sb material and the material and thickness of the electrode material layer in sample No. 3 were adjusted and multiple tests were conducted. The results showed that the energy release rate when the Ga-Sb layer 50 and the electrode material layer peeled off was greater than or equal to 0.7 J / m 2 .

[0086] In summary, the adhesion between Ga-Sb material and commonly used electrode materials (tungsten and amorphous carbon) is better than that between Sb-Te material and commonly used electrode materials, and the energy release rate of Ga-Sb material and commonly used electrode materials during peeling is greater than or equal to 0.7 J / m 2 , meeting the adhesion requirements of mass-produced phase change memory for the phase change memory layer and the electrode layer.

[0087] Since the atomic radii of Sb and Te are not much different and their bonding modes are similar, the Ga-Sb-Te material obtained by replacing the Sb atoms in the Ga-Sb material with some Te atoms can still maintain good adhesion to the electrode material layer.

[0088] In some other embodiments of the present disclosure, titanium (Ti) is also doped into the Sb-Te compound to obtain a Ti-Sb-Te material. The Ti-Sb-Te material includes Ti 0.5 Sb1Te1, Ti1Sb1Te1 and Ti2Sb1Te1. The adhesion of these Ti-Sb-Te materials to the electrode material layer (including tungsten layer and amorphous carbon layer) was tested respectively. The results can be seen in the following table. Figure 4 and Figure 5 .

[0089] like Figure 4 As shown, sample No. 4 (#04) is a sample in which a first tungsten layer 20, a Ti-Sb-Te layer 70 and a second tungsten layer 40 are deposited in sequence on the substrate 10. Sample No. 5 (#05) is a sample in which a Ti-Sb-Te layer 70 and a tungsten layer 40 are deposited in sequence on the substrate 10. Sample No. 6 (#6) is a sample in which a Ti-Sb-Te layer 70, an adhesion layer 80 and a tungsten layer 40 are deposited on the substrate 10.

[0090] Here, the material of the adhesion layer 80 includes WSiN. In some embodiments, when the material of the phase change memory layer is GST, an adhesion layer is usually provided between the phase change memory layer and the electrode layer to improve the adhesion between the phase change memory layer and the electrode layer, thereby preventing the phase change memory layer from peeling off from the electrode layer after multiple cycles.

[0091] Here, the Ti-Sb-Te layer 70 is a phase change memory material layer, wherein the composition material of the Ti-Sb-Te layer 70 is TiSbTe (i.e., the atomic ratio of Ti, Sb and Te is 1:1:1). In some other adhesion tests, the composition material of the Ti-Sb-Te layer 70 may also include Ti 0.5 Sb1Te1 or Ti2Sb1Te1.

[0092] When testing the adhesion of samples No. 4, No. 5, and No. 6, Figure 4 and Figure 5 As shown in FIG. 4 , the peeling of samples No. 4, No. 5, and No. 6 occurred at the interface corresponding to the dotted line between the two scissors symbols. Specifically, the peeling of samples No. 4 and No. 5 occurred at the interface between the Ti-Sb-Te layer 70 and the tungsten layer 40, but the energy release rate of sample No. 4 was 1.5 J / m 2 , while the energy release rate of sample No. 5 is 0.954J / m 2 This indicates that, compared to providing a tungsten layer on only one side of the phase-change memory material layer and an electrode layer of another material on the other side, providing a tungsten layer on both sides of the phase-change memory material layer simultaneously can achieve a greater energy release rate. In other words, providing tungsten layers on both sides of the phase-change memory material layer simultaneously can improve the adhesion between the phase-change memory material layer and the tungsten layers on each side, significantly reducing the probability of peeling between the phase-change memory material layer and the tungsten layer.

[0093] Sample No. 6 peeled off from the interface between the Ti-Sb-Te layer 70 and the adhesion layer 80, and the energy release rate was only 0.604 J / m 2 , which is less than the energy release rate of sample No. 5. This indicates that providing the adhesion layer 80 between the Ti—Sb—Te layer 70 and the tungsten layer 40 will increase the probability of the Ti—Sb—Te layer 70 peeling off.

[0094] The energy release rates of samples 4 and 5 were both greater than that of sample 1, indicating that the adhesion between the Ti-Sb-Te layer 70 and the tungsten layer was better than that between the Sb-Te layer 30 and the tungsten layer. The energy release rates of samples 4 and 5 were both greater than that of GST, indicating that the adhesion between the Ti-Sb-Te layer 70 and the tungsten layer was better than that between the commonly used phase-change memory material GST and the tungsten layer.

[0095] In some other embodiments, the element content of the Ti-Sb-Te material and the material of the electrode material layer in sample No. 5 were adjusted and multiple tests were conducted. The results showed that the energy release rate when the Ti-Sb-Te layer 70 and the electrode material layer peeled off was greater than or equal to 0.7 J / m 2 .

[0096] However, the phase-change memory layer using Ti-Sb-Te material still suffered from severe peeling during the preparation process. Considering the inherently low hardness and layered structure of Sb-Te material, this paper suggests that the lower hardness of Ti-Sb-Te may be due to this material. Meanwhile, this paper's research has found that Ga-Sb material has a higher hardness, as shown in the table below.

[0097] Table 1 GST and Ga with different element contents x Sb y Hardness value of the material

[0098] GST <![CDATA[Ga 55 Sb 45 ]]> <![CDATA[Ga 40 Sb 60 ]]> <![CDATA[Ga 15 Sb 85 ]]> Crystalline 3.08 5.59 5.22 4.67 Amorphous 3.03 5.06 4.24 3.52

[0099] Unit: GPa

[0100] Ga-Sb materials have high hardness values ​​in both crystalline and amorphous states, greater than that of GST materials. This is because Ga and Sb can form chemical bonds to form a four-coordinate tetrahedral structure. Sb-Te materials have a layered structure, and when doped with a certain amount of titanium, Ti-Sb-Te can still maintain a layered structure. Compared to the layered structure, the tetrahedral structure is more stable and less prone to deformation. Therefore, Ga-Sb materials are harder than Ti-Sb-Te materials. Even though the adhesion of Ti-Sb-Te materials is comparable to that of Ga-Sb materials, due to the greater hardness of Ga-Sb materials, devices using Ga-Sb materials did not peel off during the preparation process, while devices using Ti-Sb-Te materials did peel off during the preparation process.

[0101] According to the research disclosed in this paper, the Sb-Te material has a layered structure, which includes multiple layers, each layer includes multiple layers of atoms, and adjacent layers are connected by van der Waals forces. In this disclosure, when Ga is doped into Sb-Te, Ga and Sb can form chemical bonds, forming tetrahedral structures in parts of the multiple layers, such as at grain boundaries, between adjacent layers, and at defects in the layers, thereby forming a crystal structure that is interwoven with a layered structure and a small amount of tetrahedral structures as a whole, thereby improving the hardness of the entire film layer.

[0102] In the present disclosure, element A is added to the Ga-Sb-Te material. Element A can form bonds with Ga, Sb, and Te, thereby strengthening the interaction between adjacent layer structures and improving the hardness of the phase change memory layer.

[0103] Furthermore, according to the research disclosed herein, the good adhesion between the Ti-Sb-Te material and the tungsten layer is due to the Ti element forming bonds with Sb and W, strengthening the interaction between the Ti-Sb-Te material and W, thereby improving adhesion. Furthermore, the A element can form bonds with Ga, Sb, Te, and W, thereby strengthening the interaction between the A-Ga-Sb-Te material and W, thereby improving adhesion between the phase-change memory layer and the tungsten layer.

[0104] The above analysis shows that to reduce the probability of delamination between the phase-change memory layer and the electrode layer, the adhesion between the two layers should be improved. Furthermore, the hardness of the phase-change memory layer should be increased to reduce deformation and the probability of tearing under external forces. The A-Ga-Sb-Te material provided in the disclosed embodiments combines good adhesion with high hardness, reducing the probability of delamination from the electrode layer and extending the device's service life.

[0105] In the process of studying other properties of Ga-Sb-Te materials and Ti-Sb-Te materials, the present disclosure found that Ti-Sb-Te materials have a larger resistance window than Ga-Sb-Te materials, that is, a larger programming window. Therefore, in some embodiments of the present disclosure, gallium and titanium elements are simultaneously doped into the Sb-Te material to obtain a phase change memory layer with a larger resistance window and not easily peeled off from the electrode layer. Furthermore, the present disclosure also adds light elements and / or ultra-light elements to the Sb-Te material to improve the crystallization temperature, thermal stability and amorphous structure stability of the phase change memory layer.

[0106] Specifically, in this embodiment, the composition material of the phase change memory layer 201 is A-Ti-Ga-Sb-Te material; wherein the content of A is a mol%, and 0<a≤20, the content of Ga is b mol%, and 0<b≤50, the content of Sb is c mol%, and 20≤c≤90, the content of Ti is d mol%, and 0<d≤20, and the content of Te is (100-abcd) mol%. The A element is used to regulate the cycle capacity of the phase change memory unit. The composition material of the phase change memory layer can be expressed in the form of a chemical formula as A a Ti d Ga b Sb c Te (100-a-b-c-d) , where a satisfies 0<a≤20, b satisfies 0<b≤50, c satisfies 20≤c≤90, and d satisfies 0<d≤20.

[0107] Here, the content of Te element is (100-abcd) mol%, which can be understood as: when the total amount of A-Ti-Ga-Sb-Te material is 100 moles, except for a mole of A element, b moles of Ga element, c moles of Sb element and d moles of Ti element, the rest are Te elements.

[0108] For example, the content of Te element is e mol%, and satisfies 0<e≤80.

[0109] In the present disclosure, firstly, by adding the above-mentioned content of Ti element, the adhesion between the A-Ti-Ga-Sb-Te material and the electrode layer can be improved, and the A-Ti-Ga-Sb-Te material has a larger resistance window and thus a larger switching ratio.

[0110] According to the research disclosed in this disclosure, the good adhesion between the A-Ti-Ga-Sb-Te material and the tungsten electrode layer is due to the Ti atoms forming bonds with the Sb atoms and the W atoms, which strengthens the interaction force between the A-Ti-Ga-Sb-Te material and W, thereby improving adhesion.

[0111] However, the Ti content should not be too high. When the Ti content exceeds the above range, a conductive filament-like structure will form in the A-Ti-Ga-Sb-Te material, forming a conductive path and causing the phase change memory layer to be short-circuited.

[0112] In the present disclosure, by adding the aforementioned Ga content, the hardness of the phase-change memory layer can be increased without reducing the adhesion between the phase-change memory layer and the electrode layer, thereby reducing the probability of separation between the phase-change memory layer and the electrode layer. Furthermore, the addition of Ga can also increase the crystallization temperature of the phase-change memory layer.

[0113] According to the research disclosed in this paper, the Sb-Te material has a layered structure, which includes multiple layers, each layer includes multiple layers of atoms, and adjacent layers are connected by van der Waals forces. In this disclosure, when Ga is doped into Sb-Te, Ga and Sb can form chemical bonds, forming tetrahedral structures in parts of the multiple layers, such as at grain boundaries, between adjacent layers, and at defects in the layers, thereby forming a crystal structure that is interwoven with a layered structure and a small amount of tetrahedral structures as a whole, thereby improving the hardness of the entire film layer.

[0114] However, the gallium content should not be too high. According to the research disclosed in this paper, the solid solubility of Ga in Ti-Sb-Te materials is low. If the Ga content exceeds the above content, the tendency of phase separation in Ti-Ga-Sb-Te materials will be greatly increased, and Sb phase will be easily generated.

[0115] In some embodiments, the A element improves the cycle capability of the phase change memory by suppressing the appearance of the Sb phase. For example, the A element includes at least one of carbon, nitrogen, oxygen, or silicon.

[0116] Atoms A can form bonds with Ti, Ga, Sb, and Te atoms, reducing the probability of Sb atoms forming bonds with each other. This reduces the probability of the Sb phase appearing in the phase-change memory layer when the A content is within the aforementioned range. Furthermore, even if the Sb phase does appear, A can be enriched at the grain boundaries of the Sb phase, inhibiting its grain growth and thus controlling its content within a certain range.

[0117] According to the research disclosed in this paper, the Sb phase has a low crystallization temperature and good thermal stability in the crystalline state, but poor stability in the amorphous state. This means that once the Sb phase precipitates in the phase-change memory layer, it will not participate in the phase change process, resulting in a smaller difference between the high-resistance and low-resistance states of the phase-change memory layer, that is, a smaller resistance window.

[0118] The cyclability of a phase-change memory can be characterized by the number of cycles it can undergo while meeting the required resistance window. In the present disclosure, by adding the aforementioned content of element A, the probability of the Sb phase appearing in the phase-change memory layer can be reduced. Once the Sb phase appears, its grain growth can be suppressed, and the Sb phase content can be controlled within a certain range. This ensures that the resistance window of the phase-change memory layer remains within the required range over a greater number of cyclic phase changes, thereby improving the cyclability of the phase-change memory.

[0119] In some embodiments, element A can significantly increase the crystallization temperature of the phase change memory layer, thereby improving the thermal stability of the phase change memory layer. Element A can also improve the stability of the amorphous structure of the phase change memory layer, thereby increasing the tolerance of the phase change memory layer to external stress and ambient temperature, thereby improving the data retention capability of the phase change memory.

[0120] In some embodiments, element A can form bonds with Ti, Ga, Sb, and Te, strengthening the interaction between adjacent layers and thereby increasing the hardness of the phase-change memory layer. Furthermore, element A can form bonds with W, thereby strengthening the interaction between the A-Ti-Ga-Sb-Te material and W, thereby improving the adhesion between the phase-change memory layer and the tungsten layer.

[0121] Here, the content of element A should not be too high. According to the research disclosed in this disclosure, adding element A to Ti-Ga-Sb-Te can improve the stability of the amorphous structure. If the content of element A exceeds the above range, the resistance of the phase change memory layer will remain at a certain resistance value, and high and low resistance states cannot be achieved, that is, reversible phase transition cannot be achieved.

[0122] The A-Ti-Ga-Sb-Te material disclosed herein has flexible and controllable composition adjustment. The proportion of each element can be adjusted within the above-mentioned content range according to performance and cost requirements to obtain the required phase change memory.

[0123] For example, in some embodiments, when the Ti element content is high, the adhesion between the phase change memory layer and the electrode layer is high, and thus the probability of peeling off between the phase change memory layer and the electrode layer is reduced. This can reduce production risks and reduce the probability of peeling off between the phase change memory layer and the electrode layer during repeated phase changes of the phase change memory, thereby improving the cycle capacity of the phase change memory.

[0124] In some embodiments, when the content of element A is high, the phase change memory layer has a higher crystallization temperature, a larger resistance window, better thermal stability and amorphous structure stability, and thus the phase change memory has better data retention and cycle capability.

[0125] In some embodiments, when the content of element A is low, the phase-change memory layer has a faster erase and write speed.

[0126] In some embodiments, when the Ga content is high, the hardness of the phase change memory layer is high, and thus the probability of peeling off between the phase change memory layer and the electrode layer is reduced. This can reduce production risks and reduce the probability of peeling off between the phase change memory layer and the electrode layer during repeated phase changes of the phase change memory, thereby improving the cycle capacity of the phase change memory.

[0127] In some embodiments, when the Ga content is low, the resistance window of the phase change memory layer is larger, and the phase change memory has a larger switching ratio, which can improve the speed and accuracy of data reading.

[0128] In summary, in the present disclosure, the contents of Ti, Ga and A can be flexibly adjusted according to actual requirements for cost, cycle capability, data retention, switching ratio and erase / write speed to obtain the required phase change memory.

[0129] In some embodiments, the A element can increase the crystallization temperature of the A-Ti-Ga-Sb-Te material to greater than or equal to 250° C., which is much greater than the crystallization temperature of the Sb-Te material of 120° C.

[0130] In some embodiments, the chemical formula of the phase change memory layer 201 is C 10 Ti 10 Ga 10 Sb 40 Te 30 , O 20 Ti 12 Ga1Sb 47 Te 20 、N5Ti 15 Ga5Sb 60Te 15 、Si1Ti1Ga 15 Sb 78 Te5、C 15 Ti 20 Ga 30 Sb 20 Te 15 、Si3Ti5Ga 50 Sb 32 Te 10 、N1Ti1Ga7Sb 90 Te1, C 10 Ti 10 Ga 10 Sb 20 Te 50 、C1Ti1Ga1Sb 20 Te 77 One of them.

[0131] In some embodiments, after comprehensively considering the negative impact of Ga on the resistance window and phase composition, and its positive impact on adhesion and hardness, the Ga content is further limited to meet the following requirements: 5 mol% ≤ b mol% ≤ 10 mol%. This minimizes the Sb phase content within the A-Ti-Ga-Sb-Te material, ensuring that the resistance window of the phase-change memory layer remains within the required range over a wide range of phase-change cycles, thereby improving the cyclability of the phase-change memory. Furthermore, the A-Ti-Ga-Sb-Te material exhibits high adhesion and hardness, a high crystallization temperature, good thermal stability, and amorphous structural stability, resulting in a more balanced performance of the phase-change memory, thus achieving better overall performance.

[0132] Furthermore, the comparison of the energy release rates of samples No. 4 and No. 5 in the above experiment shows that, compared to providing a tungsten layer on only one side of the phase-change memory material layer and an electrode layer made of another material on the other side, providing a tungsten layer on both sides of the phase-change memory material layer can achieve a higher energy release rate. Therefore, in some embodiments, the electrode layers on both sides of the phase-change memory layer 201 are both made of tungsten.

[0133] In some embodiments, the electrode layers on both sides of the phase-change memory layer 201 may be a middle electrode 204 and a top electrode 205, and both the middle electrode 204 and the top electrode 205 are made of tungsten. Because the adhesion of the A-Ti-Ga-Sb-Te material to tungsten is better than its adhesion to amorphous carbon, using tungsten for the middle and top electrodes can reduce the probability of delamination between the phase-change memory layer and the middle and top electrodes, thereby extending the service life of the phase-change memory.

[0134] In some embodiments, as Figure 3As shown, the materials of the middle electrode and top electrode of the phase change memory cell can be amorphous carbon, and an electrode layer 206 made of tungsten is provided between the middle electrode 204 and the phase change memory layer 201. Another electrode layer 206 made of tungsten is provided between the top electrode 205 and the phase change memory layer 201. Here, a double-layer electrode is provided on both sides of the phase change memory layer. On the one hand, the middle electrode 204 and the top electrode 205 made of amorphous carbon have low thermal conductivity, which can effectively lock heat near the phase change memory layer 201 and reduce thermal crosstalk caused by thermal diffusion. On the other hand, the two electrode layers 206 made of tungsten can improve the adhesion between the phase change memory layer 201 and the electrode layer 206, reducing the probability of peeling between the phase change memory layer 201 and the electrode layer 206. The two electrode layers 206 can also prevent impurities in the middle electrode 204 and the top electrode 205 from diffusing into the phase change memory layer 201, causing device performance degradation.

[0135] In some embodiments, the adhesion between the phase change memory layer and the electrode layer is characterized by an energy release rate, and the energy release rate is greater than or equal to 0.7 J / m 2 .

[0136] The present disclosure also provides a method for preparing a phase change memory, the method comprising:

[0137] S100: forming a first conductive line layer and a memory cell material layer stacked along a first direction; wherein the memory cell material layer includes a phase change memory material layer, and the phase change memory material layer includes an A-Ga-Sb-Te material, wherein the content of A is a mol%, and 0<a≤20, the content of Ga is b mol%, and 0<b≤50, the content of Sb is c mol%, and 20≤c≤90, and the content of Te is (100-abc) mol%. The first direction is perpendicular to the plane where the first conductive line layer is located;

[0138] S200: forming a plurality of first isolation structures penetrating the first conductive line layer and the memory cell material layer; wherein each first isolation structure extends along the second direction, and the plurality of first isolation structures are arranged in parallel along the third direction; the plurality of first isolation structures divide the first conductive line layer into a plurality of first conductive lines; and the third direction and the second direction are perpendicular to the first direction.

[0139] S300: forming a second conductive line layer covering the first isolation structure and the memory cell material layer;

[0140] S400: forming a plurality of second isolation structures penetrating the second conductive line layer and the storage unit material layer; wherein each second isolation structure extends along the third direction, and the plurality of second isolation structures are arranged in parallel along the second direction; the plurality of second isolation structures divide the second conductive line layer into a plurality of second conductive lines; the plurality of first isolation structures and the plurality of second isolation structures divide the storage unit material layer into a plurality of mutually independent phase change memory cells, each phase change memory cell including a phase change memory layer, and the A element in the phase change memory layer is used to improve the data retention of the phase change memory cell.

[0141] Here, the first direction is defined as the Z direction, the second direction is defined as the X direction, and the third direction is defined as the Y direction.

[0142] For example, the materials of the first and second isolation structures include, but are not limited to, silicon nitride, silicon oxide, and the like. The first and second isolation structures are used to electrically isolate independent phase-change memory cells. The material of the filling layer has low thermal conductivity, which can reduce heat transfer between adjacent phase-change memory cells, thereby reducing crosstalk caused by heat transfer and ensuring high reliability of the phase-change memory.

[0143] It should be noted that the second isolation structure only penetrates the second conductive line layer and the memory cell material layer along the first direction, but does not penetrate the first conductive line layer.

[0144] Here, in step S200, the first isolation structure divides the first conductive line layer, and the remaining material of the first conductive line layer forms a plurality of first conductive lines. In addition, each first conductive line extends along the second direction, and the plurality of first conductive lines are arranged in parallel along the third direction.

[0145] In step S400, the second isolation structure divides the second conductive line layer, and the remaining material of the second conductive line layer forms a plurality of second conductive lines. In addition, each second conductive line extends along a third direction, and the plurality of second conductive lines are arranged in parallel along the third direction.

[0146] The first isolation structure and the second isolation structure divide the memory cell material layer into a plurality of independent phase-change memory cells, which are arranged in an array. Each phase-change memory cell includes a phase-change memory layer. Each phase-change memory cell is connected to a first conductive line and a second conductive line at both ends along a first direction, respectively, for applying an operating pulse to the phase-change memory cell via the first conductive line and the second conductive line, thereby changing the resistance of the phase-change memory layer of the phase-change memory cell.

[0147] In some embodiments, the composition material of the phase change memory layer also includes Ti element, forming A-Ti-Ga-Sb-Te material; wherein the content of A is a mol%, and 0<a≤20, the content of Ga is b mol%, and 0<b≤50, the content of Sb is cmol%, and 20≤c≤90, the content of Ti is d mol%, and 0<d≤20, and the content of Te is (100-abcd) mol%; the A element is used to improve the cycle capacity of the phase change memory unit.

[0148] The composition of the phase change memory layer can be expressed in the form of a chemical formula as A a Ti d Ga b Sb c Te (100-a-b-c-d) , where a satisfies 0<a≤20, b satisfies 0<b≤50, c satisfies 20≤c≤90, and d satisfies 0<d≤20.

[0149] In some embodiments, the content of Te element is e mol %, and satisfies 0<e≤80.

[0150] In some embodiments, the A element includes at least one of carbon, nitrogen, oxygen, or silicon.

[0151] In some embodiments, the phase change memory material layer may be formed by physical vapor deposition, chemical vapor deposition (CVD), atomic layer deposition (ALD), plasma doping, etc. Here, physical vapor deposition includes but is not limited to magnetron co-sputtering and electron beam evaporation.

[0152] In this embodiment, the phase change memory material layer may be formed by co-sputtering, or by co-sputtering and plasma doping.

[0153] For example, according to C a Ti d Ga b Sb c Te (100-a-b-c-d) The C, Ti, Ga, Sb, and Te content in the phase change memory material layer is obtained by co-sputtering a Sb-Te alloy target, a Sb single-substance target, a Ti single-substance target, a Ga single-substance target, and a C (carbon) single-substance target. Here, the C single-substance target can also be replaced with a TiC target.

[0154] For example, according to Si a Ti d Ga b Sb c Te (100-a-b-c-d)The Si, Ti, Ga, Sb and Te elements are added to the Si-Ti-Ga-Sb-Te phase change memory material layer by co-sputtering an Sb-Te alloy target, an Sb single target, a Ti single target, a Ga single target and an Si single target.

[0155] For example, according to N a Ti d Ga b Sb c Te (100-a-b-c-d) The N, Ti, Ga, Sb, and Te content in the phase change memory material layer is obtained by co-sputtering a Sb-Te alloy target, a Sb single target, a Ti single target, a Ga single target, and a TiN target. Here, the TiN target can also be replaced by a GaN target.

[0156] For example, according to O a Ti d Ga b Sb c Te (100-a-b-c-d) The O, Ti, Ga, Sb, and Te content in the phase change memory material layer is obtained by co-sputtering a Sb-Te alloy target, a Sb single target, a Ti single target, a Ga single target, and a TiO2 target. Here, the TiO2 target can also be replaced by a Ga2O3 target.

[0157] For example, according to N a Ti d Ga b Sb c Te (100-a-b-c-d) The N, Ti, Ga, Sb, and Te element contents are adjusted by co-sputtering an Sb-Te alloy target, an Sb single target, a Ti single target, and a Ga single target in a nitrogen atmosphere to obtain an N-Ti-Ga-Sb-Te phase change memory material layer.

[0158] For example, according to O a Ti d Ga b Sb c Te (100-a-b-c-d) The O, Ti, Ga, Sb and Te elements are co-sputtered in an oxygen atmosphere using a Sb-Te alloy target, a Sb single target, a Ti single target and a Ga single target to obtain an O-Ti-Ga-Sb-Te phase change memory material layer.

[0159] Illustratively, the Sb—Te alloy target includes a Sb 2 Te 3 alloy target, a Sb 2 Te 1 target, or a Sb 1 Te 1 target.

[0160] In the present disclosure, in order to address the problems of low crystallization temperature, poor thermal stability, poor amorphous structure stability and easy peeling from the electrode layer of the Sb-Te material, by adding the above-mentioned content of Ti element, the adhesion of the Ti-Sb-Te material can be improved, and the Ti-Sb-Te material has a large resistance window and a short crystallization time, and thus has a large switching ratio and a fast erase operation speed. By adding the above-mentioned content of Ga element, the hardness of the phase change memory layer can be improved without reducing the adhesion of the phase change memory layer and the electrode layer, thereby reducing the probability of peeling of the phase change memory layer and the electrode layer. And the addition of Ga element can also increase the crystallization temperature of the phase change memory layer. By adding the above-mentioned content of A element, the crystallization temperature of the phase change memory layer can be greatly increased, thereby improving the thermal stability and amorphous structure stability of the phase change memory layer, and thereby improving the data retention capability of the phase change memory. Furthermore, element A can reduce the probability of the Sb phase appearing in the phase-change memory layer, and can also inhibit the grain growth of the Sb phase after the Sb phase appears, controlling the content of the Sb phase within a certain range, thereby ensuring that the resistance window of the phase-change memory layer can be maintained within the required range during more cyclic phase changes, thereby improving the cyclic capacity of the phase-change memory.

[0161] In summary, the present disclosure reduces the probability of separation between the phase-change memory layer and the electrode layer by adding Ti, Ga, and A to the Sb-Te material, lowering production risks and expanding the range of phase-change materials suitable for large-scale production. Furthermore, it enables faster programming speeds for phase-change memories, while also improving their cycling performance and data retention.

[0162] In some embodiments, the Ga content satisfies the following conditions: 5 mol% ≤ b mol% ≤ 10 mol%. This allows the A-Ti-Ga-Sb-Te to have a suitable resistance window, high adhesion and hardness, a high crystallization temperature, and a stable phase composition, resulting in a more balanced performance and better overall performance.

[0163] In some embodiments, as Figure 3 As shown, the phase change memory cell 200 further includes a bottom electrode 202, a gate layer 203, an intermediate electrode 204, and a top electrode 205 stacked in sequence along the first direction. Correspondingly, the step of forming the memory cell material layer in S100 further includes:

[0164] Before forming the phase-change memory material layer, a bottom electrode material layer, a gate material layer and an intermediate electrode material layer are sequentially formed on the first conductive line layer;

[0165] After forming the phase-change memory material layer, forming a top electrode material layer on the phase-change memory material layer;

[0166] The step of forming a plurality of first isolation structures penetrating the memory cell material layer in S200 further includes:

[0167] forming a plurality of first isolation structures penetrating the bottom electrode material layer, the gate material layer, the middle electrode material layer, and the top electrode material layer;

[0168] The step of forming a plurality of second isolation structures penetrating the memory cell material layer in S400 further includes:

[0169] A plurality of second isolation structures are formed that penetrate the bottom electrode material layer, the gate material layer, the intermediate electrode material layer, and the top electrode material layer; wherein the plurality of first isolation structures and the plurality of second isolation structures divide the bottom electrode material layer, the gate material layer, the intermediate electrode material layer, and the top electrode material layer into a plurality of bottom electrodes, a plurality of gate layers, a plurality of intermediate electrodes, and a plurality of top electrodes; each phase change memory cell includes a bottom electrode, a gate layer, an intermediate electrode, and a top electrode stacked in sequence along a first direction, and the phase change memory layer is located between the intermediate electrode and the top electrode.

[0170] In some embodiments, the phase change memory unit includes two electrode layers, the two electrode layers are arranged on opposite sides of the phase change memory layer along a first direction, and the two electrode layers are in contact with the phase change memory layer; the adhesion between the phase change memory layer and the electrode layer is characterized by an energy release rate, and the energy release rate is greater than or equal to 0.7 J / m 2 .

[0171] It should be noted that in some embodiments, the two electrode layers may be a middle electrode and a top electrode. Both the middle electrode and the top electrode are made of tungsten. The adhesion of the A-Ti-Ga-Sb-Te material to tungsten is better than its adhesion to amorphous carbon. Therefore, using tungsten for the middle and top electrodes can reduce the probability of delamination between the phase-change memory layer and the middle and top electrodes, thereby extending the service life of the phase-change memory.

[0172] In some other embodiments, the middle electrode and top electrode of the phase-change memory cell may be made of amorphous carbon, and an electrode layer made of tungsten is provided between the middle electrode and the phase-change memory layer. Another electrode layer made of tungsten is provided between the phase-change memory layer and the top electrode layer.

[0173] Correspondingly, the step of forming the memory cell material layer in S100 further includes:

[0174] Before forming the phase change memory material layer, forming a first electrode material layer;

[0175] After forming the phase change memory material layer, a second electrode material layer is formed on the phase change memory material layer; wherein both electrode material layers are in contact with the phase change memory material layer; the adhesion between the phase change memory material layer and the electrode material layer is characterized by an energy release rate, and the energy release rate is greater than or equal to 0.7 J / m 2 ;

[0176] The step of forming a plurality of first isolation structures penetrating the memory cell material layer in S200 further includes:

[0177] forming a plurality of first isolation structures penetrating the first electrode material layer and the second electrode material layer;

[0178] The step of forming a plurality of second isolation structures penetrating the memory cell material layer in S400 further includes:

[0179] A plurality of second isolation structures are formed that penetrate the first electrode material layer and the second electrode material layer; wherein the plurality of first isolation structures and the plurality of second isolation structures divide the first electrode material layer and the second electrode material layer into a plurality of first electrodes and a plurality of second electrodes, and in each phase change memory cell, the first electrode layer and the second electrode layer are arranged on opposite sides of the phase change memory layer along the first direction.

[0180] In some embodiments, the first electrode layer is located between the middle electrode and the phase-change memory layer, and the second electrode is located between the phase-change memory layer and the top electrode.

[0181] Here, both electrode layers are made of tungsten. The A-Ti-Ga-Sb-Te material adheres better to tungsten than to amorphous carbon. This reduces the likelihood of delamination between the phase-change memory layer and the electrode layer, extending the lifespan of the phase-change memory.

[0182] The above embodiments are merely illustrative of the principles and effects of this disclosure and are not intended to limit this disclosure. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of this disclosure. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical concepts disclosed herein shall be covered by the claims of this disclosure.

Claims

1. A phase change memory, characterized in that: include: A first conductive line, a phase-change memory unit, and a second conductive line are sequentially stacked along a first direction, the first conductive line extends along a second direction, the second conductive line extends along a third direction, and the first direction, the second direction, and the third direction are perpendicular to each other; The phase-change memory unit includes a phase-change memory layer, wherein the composition material of the phase-change memory layer includes A-Ga-Sb-Te material, wherein the content of A is a mol%, and 0<a≤20, the content of Ga is b mol%, and 0<b≤50, the content of Sb is cmol%, and 20≤c≤90, and the content of Te is (100-abc) mol%. The A element includes at least one of carbon, nitrogen, oxygen or silicon, and is used to regulate the cycle capacity of the phase-change memory unit. The phase-change memory unit further includes two electrode layers, which are arranged on opposite sides of the phase-change memory layer along the first direction, and the two electrode layers are in contact with the phase-change memory layer; The adhesion between the phase change memory layer and the electrode layer is characterized by an energy release rate, and the energy release rate is greater than or equal to 0.7 J / m 2 .

2. The phase change memory according to claim 1, wherein: The phase change memory layer also includes Ti in its constituent material. The content of Ti is d mol%, and 0<d≤20. The content of Te is (100-abcd) mol%.

3. The phase change memory according to claim 1, wherein: The Ga content satisfies: 5 mol%≤1 mol%≤10 mol%.

4. The phase change memory according to claim 1, wherein: The material of the electrode layer includes tungsten.

5. A method for preparing a phase change memory, characterized in that: include: A first conductive line layer and a memory cell material layer are stacked along a first direction; wherein the memory cell material layer includes a first electrode material layer, a phase change memory material layer, and a second electrode material layer stacked along the first direction, both of the electrode material layers are in contact with the phase change memory material layer, and the material of the phase change memory material layer includes an A-Ga-Sb-Te material, wherein the content of A is a mol%, and 0<a≤20, the content of Ga is b mol%, and 0<b≤50, the content of Sb is c mol%, and 20≤c≤90, and the content of Te is (100-abc) mol%, and the A element includes at least one of carbon, nitrogen, oxygen, or silicon; the adhesion between the phase change memory material layer and the electrode material layer is characterized by an energy release rate, and the energy release rate is greater than or equal to 0.7 J / m 2 The first direction is perpendicular to the plane where the first conductive line layer is located; forming a plurality of first isolation structures penetrating the first conductive line layer and the memory cell material layer; wherein each first isolation structure extends along the second direction, and the plurality of first isolation structures are arranged in parallel along a third direction; the plurality of first isolation structures divide the first conductive line layer into a plurality of first conductive lines; and the third direction and the second direction are perpendicular to the first direction. forming a second conductive line layer covering the first isolation structure and the memory cell material layer; A plurality of second isolation structures are formed that penetrate the second conductive line layer and the storage unit material layer; wherein each second isolation structure extends along the third direction, and the plurality of second isolation structures are arranged in parallel along the second direction; the plurality of second isolation structures divide the second conductive line layer into a plurality of second conductive lines; the plurality of first isolation structures and the plurality of second isolation structures divide the storage unit material layer into a plurality of mutually independent phase change memory units, each of the phase change memory units including a phase change memory layer and two electrode layers arranged on both sides of the phase change memory layer along the first direction, and the A element in the phase change memory layer is used to regulate the cycle capacity of the phase change memory unit.

6. The method for preparing a phase change memory according to claim 5, wherein: The phase change memory material layer also includes Ti element; wherein the content of Ti is d mol%, and 0<d≤20, and the content of Te is (100-abcd) mol%.

7. The method for preparing a phase change memory according to claim 6, wherein: The Ga content satisfies: 5 mol%≤b mol%≤10 mol%.

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