Crystalline taos with ultrahigh memory window x Resistive random access memory and method of making the same

Abstract

Crystalline taos with ultrahigh memory window x Resistive random access memory and its preparation method, belong to semiconductor thin film and its resistive random access memory technical field. Mainly include: 1) handle (100) oriented single crystal Si substrate; 2) prepare (222) oriented ITO bottom electrode on the substrate by magnetron sputtering method; 3) grow the crystalline TaO with the main crystal direction (100) and the maximum grain size of 30 nm on the ITO bottom electrode by radio frequency reactive magnetron sputtering method x Thin film as resistance layer; 4) deposit Ta electrode on the resistance layer by magnetron sputtering method. The crystalline TaO with the main crystal direction (100) and the maximum grain size of 30 nm is prepared x The thin film has good thin film crystal structure and grain size, fast growth speed and controllable thin film composition, and the crystalline TaO with the thin film as the resistance layer x The resistive random access memory shows ultrahigh memory window, very low operating voltage and strong durability, and can be crystalline TaO x The application provides certain technical guidance for commercialization and industrial application of the resistive random access memory.

Description

Technical Field

[0001] This invention relates to the field of semiconductor thin films and their resistive switching memory technology, specifically to a crystalline TaO with an ultra-high memory window. x Resistive random access memory and its fabrication method. Background Technology

[0002] In recent years, information technology has developed rapidly, and traditional storage devices can no longer meet people's storage requirements. As one of the most attractive alternatives to NAND flash memory, resistive random access memory (RRAM) has attracted widespread attention due to its fast read / write speeds, simple structure, durability, reliability, low power consumption, and ease of integration. TaO... x As one of the most promising resistive random access memory (RRAMs), the most common fabrication method is magnetron sputtering.

[0003] Non-stoichiometric TaO prepared by magnetron sputtering x Different components of the thin film can significantly affect its microstructure and resistive switching properties, thereby influencing TaO. x Storage window and power consumption of resistive random access memory (RRAM). TaO grown by magnetron sputtering. x During the thin film process, because TaO x The thin film is a polycrystalline structure, so TaO grown under different process parameters... x The preferred orientation, grain size, and resistive switching properties of thin films vary greatly. Therefore, the study focuses on crystalline TaO with ultra-high storage windows. x The fabrication of resistive random access memory (RRAM) is a highly promising project. Summary of the Invention

[0004] Technical problem solved: To address the problems existing in the prior art, this invention provides a crystalline TaO with an ultra-high storage window. x Resistive switching memory and its fabrication method: obtaining crystalline TaO with different compositions by optimizing the magnetron sputtering process and adjusting the oxygen partial pressure. x Thin film, thereby optimizing TaO x The resistive switching performance of resistive random access memory (RRAM) increases the storage window, reduces the operating voltage, and improves reliability.

[0005] Technical solution: A crystalline TaO with an ultra-high storage window x The fabrication method of resistive random access memory (RRAM) includes the following steps:

[0006] Step 1. Processing the (100) oriented single-crystal Si substrate, specifically including: cutting a 4-inch (100) oriented single-crystal Si wafer into 1×1cm pieces. 2 The Si substrate was then ultrasonically cleaned in acetone, anhydrous ethanol and deionized water for 25-30 min in sequence, and finally dried with nitrogen.

[0007] Step 2. Prepare a (222) oriented ITO thin film as a bottom electrode on the substrate obtained in Step 1 by magnetron sputtering. The specific process parameters include: 80W radio frequency reactive sputtering power, 1Pa sputtering pressure, 500℃ deposition temperature and 15% oxygen concentration in the sputtering atmosphere.

[0008] Step 3. On the ITO bottom electrode obtained in Step 2, crystalline TaO with a main crystal orientation of (100) and a maximum grain size of 30 nm is grown by radio frequency reactive magnetron sputtering. x The thin film is used as the resistive layer. Specific process parameters include: deposition and crystallization temperature of 750℃, RF reactive sputtering power of 100W, sputtering pressure of 1.6Pa, and oxygen concentration in the sputtering atmosphere ranging from 10% to 30%.

[0009] Step 4. The crystalline TaO obtained in Step 3 x A Ta electrode with good conductivity was deposited on the resistive layer by magnetron sputtering. The DC reaction power was 40 W, the sputtering pressure was 1 Pa, the deposition temperature was 750 °C, and the oxygen concentration in the sputtering atmosphere was 0%, resulting in crystalline TaO with an ultra-high storage window. x Resistive random access memory (RRAM).

[0010] Preferably, in step two, the magnetron sputtering method uses an ITO target with a purity of 99.95%, and the chamber pressure is 2 × 10⁻⁶. -4 Pa, the target and substrate spacing is 60 mm, the purity of the working gas argon and the reactant gas oxygen is 99.999%, the total gas volume in the chamber is set to 40 sccm, the deposition time of the ITO bottom electrode is 10 min, and the deposition thickness is 80 nm.

[0011] Preferably, in step three, the sputtering target in the radio frequency reactive magnetron sputtering method is a Ta target with a purity of 99.95%, and the chamber pressure is 2×10⁻⁶. -4 Pa, the target and substrate spacing is 60 mm, the purity of both the working gas argon and the reactant gas oxygen is 99.999%, the total gas volume in the chamber is set to 40 sccm, and the crystalline TaO is used. x The film deposition time was 30 min, and the deposition thickness was 180 nm.

[0012] Preferably, in step four, when depositing a Ta electrode with good conductivity using magnetron sputtering, the sputtering target is a Ta target with a purity of 99.95%, and the chamber pressure is 2 × 10⁻⁶. -4 Pa, the target and substrate spacing is 60 mm, the purity of the working gas argon and the reaction gas oxygen is 99.999%, the total gas volume in the chamber is set to 40 sccm, the deposition time of the Ta electrode is 10 min, and the deposition thickness is 60 nm.

[0013] Preferably, in step four, when depositing a Ta electrode with good conductivity using magnetron sputtering, a metal mask is used to attach the electrode to the TaO. x On the surface of the resistive layer, the deposited Ta electrode is cylindrical.

[0014] A crystalline TaO with an ultra-high storage window prepared by the above method x Resistive random access memory (RRAM).

[0015] Beneficial effects: Compared with the prior art, the beneficial effects of the present invention are as follows:

[0016] 1. This invention prepares crystalline TaO with a main crystal orientation of (100) and a maximum grain size of 30 nm. x Thin film, confirming crystalline TaO x Optimal deposition and crystallization temperature, optimal radio frequency power, and optimal sputtering gas pressure were achieved for thin-film magnetron sputtering, resulting in crystalline TaO. x Rapid growth of thin films, while accurately controlling the crystalline state of TaO. x The ratio of oxygen to tantalum atoms in the thin film.

[0017] 2. Prepared crystalline TaO x Resistive random access memory (RSM) has an extremely high storage window, very low operating voltage, and strong durability retention, making it suitable for use with crystalline TaO2. x This provides some technical guidance for the commercialization and industrial application of resistive random access memory (RRAM). Attached Figure Description

[0018] Figure 1 This is a flowchart of the process steps of the present invention;

[0019] Figure 2 The crystalline TaO with an ultra-high storage window described in this invention x Schematic diagram of the mezzanine structure of resistive random access memory;

[0020] Figure 3 The ultra-high crystallinity ITO bottom electrode and TaO in Example 4 of this invention x XRD diffraction pattern of the thin film;

[0021] Figure 4 (a) is the current-voltage test curve of Embodiment 1 of the present invention. Figure 4 (b) is the current-voltage test curve of Embodiment 2 of the present invention.

[0022] Figure 5 (a) is the current-voltage test curve of Embodiment 3 of the present invention. Figure 5 (b) is a storage window diagram of Embodiment 3 of the present invention.

[0023] Figure 6 (a) is the current-voltage test curve of Embodiment 4 of the present invention. Figure 6 (b) is a storage window diagram of Embodiment 4 of the present invention.

[0024] Figure 7 (a) is the current-voltage test curve of Embodiment 5 of the present invention. Figure 7 (b) is a storage window diagram of Embodiment 5 of the present invention.

[0025] Figure 8 (a) is a typical current-voltage test curve for Ta thin films. Figure 8 (b) is the current-voltage test curve of the Ta electrode film used in Examples 1-5 of the present invention.

[0026] The numbers in the diagram represent the following: 1. Si substrate; 2. ITO bottom electrode; 3. Crystalline TaO x 4. Ta electrode. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Example 1

[0029] like Figure 1 As shown, the present invention provides a crystalline TaO with an ultra-high storage window. x The fabrication method of resistive random access memory includes the following steps:

[0030] 1) Cut a 4-inch (100) oriented single-crystal Si wafer into 1×1cm pieces. 2 The Si substrate 1 was then ultrasonically cleaned in acetone, anhydrous ethanol and deionized water for 25-30 minutes in sequence, and finally dried with nitrogen gas.

[0031] 2) Place the treated substrate into the chamber and evacuate to 2×10⁻⁶. -4Pa, using ITO (99.95%) as the sputtering target, an ITO thin film with (222) orientation was prepared on the substrate obtained in step 1) by magnetron sputtering to serve as the ITO bottom electrode 2. The distance between the target and the substrate was 60 mm, the RF reactive sputtering power was 80 W, the sputtering pressure was 1 Pa, the deposition temperature was 500 °C, the oxygen flow rate in the sputtering atmosphere was 6 sccm, the argon flow rate was 34 sccm, the purity of the working gas argon and the reactive gas oxygen was 99.999%, the deposition time was 10 min, and the deposition thickness was 80 nm.

[0032] 3) Place the ITO bottom electrode 2 obtained in step 2) into the chamber and evacuate to 2×10⁻⁶. -4 Pa, using Ta (99.95%) as the sputtering target, crystalline TaO with a main crystal orientation of (100) and a maximum grain size of 30 nm was prepared on the bottom electrode obtained in step 2) by radio frequency reactive magnetron sputtering. x Thin film 3 is used as the resistive layer. The target and substrate spacing is 60 mm. The RF reactive sputtering power is 100 W, the sputtering pressure is 1.6 Pa, the deposition and crystallization temperature is 750 °C, the oxygen flow rate in the sputtering atmosphere is 4 sccm, the argon flow rate is 36 sccm, the purity of the working gas argon and the reactive gas oxygen is 99.999%, the deposition time is 30 min, and the deposition thickness is 180 nm.

[0033] 4) Take the crystalline TaO obtained in step 3) x The resistive layer was placed in the chamber and a vacuum was drawn to 2×10⁻⁶. -4 Pa, using Ta (99.95%) as the sputtering target, obtained in step 3) by magnetron sputtering. x Ta electrode 4 was fabricated on a resistive layer with a target-substrate spacing of 60 mm, a DC reaction power of 40 W, a sputtering pressure of 1 Pa, a deposition temperature of 750 °C, an oxygen flow rate of 0 sccm, an argon flow rate of 40 sccm, an argon purity of 99.999%, a deposition time of 10 min, and a deposition thickness of 60 nm. A metal mask was used to deposit the Ta electrode on the TaO layer. x On the surface of the resistive layer, the deposited Ta electrode is cylindrical.

[0034] In this embodiment, crystalline TaO was fabricated. x Resistive random access memory (RRAM), its simple mezzanine structure is as follows: Figure 2 As shown, its current-voltage curve is as follows: Figure 4 As shown in (a), it can be seen from the figure that the high and low resistance values ​​of this device are relatively close, the resistance is gradually changing, and the current jump area is relatively small.

[0035] Example 2

[0036] Same as Example 1, except that step 3) is as follows:

[0037] Place the ITO bottom electrode 2 obtained in step 2) into the chamber and evacuate to 2×10⁻⁶. -4 Pa, using Ta (99.95%) as the sputtering target, crystalline TaO with a main crystal orientation of (100) and a maximum grain size of 30 nm was prepared on the bottom electrode obtained in step 2) by radio frequency reactive magnetron sputtering. x Thin film 3 is used as the resistive layer. The target and substrate spacing is 60 mm. The RF reactive sputtering power is 100 W, the sputtering pressure is 1.6 Pa, the deposition and crystallization temperature is 750 °C, the oxygen flow rate in the sputtering atmosphere is 6 sccm, the argon flow rate is 34 sccm, the purity of the working gas argon and the reactive gas oxygen is 99.999%, the deposition time is 30 min, and the deposition thickness is 180 nm.

[0038] In this embodiment, crystalline TaO was fabricated. x The current-voltage curve of a resistive random access memory is as follows: Figure 4 As shown in (b), it can be seen from the figure that the high and low resistance values ​​of this device are relatively close, the resistance also shows a gradual trend, and the current jump area is also small.

[0039] Example 3

[0040] Same as Example 1, except that step 3) is as follows:

[0041] Place the ITO bottom electrode 2 obtained in step 2) into the chamber and evacuate to 2×10⁻⁶. -4 Pa, using Ta (99.95%) as the sputtering target, crystalline TaO with a main crystal orientation of (100) and a maximum grain size of 30 nm was prepared on the bottom electrode obtained in step 2) by radio frequency reactive magnetron sputtering. x Thin film 3 is used as the resistive layer. The target and substrate spacing is 60 mm. The RF reactive sputtering power is 100 W, the sputtering pressure is 1.6 Pa, the deposition and crystallization temperature is 750 °C, the oxygen flow rate in the sputtering atmosphere is 8 sccm, the argon flow rate is 32 sccm, the purity of the working gas argon and the reactive gas oxygen is 99.999%, the deposition time is 30 min, and the deposition thickness is 180 nm.

[0042] In this embodiment, crystalline TaO was fabricated. x The current-voltage curve of a resistive random access memory is as follows: Figure 5 As shown in (a), its storage window is as follows Figure 5 As shown in (b), it can be seen from the figure that this resistive switching device has a significant resistance switching effect, very obvious resistance switching characteristics, and an opening voltage of 8.7V, exhibiting excellent resistive switching performance.

[0043] Example 4

[0044] Same as Example 1, except that step 3) is as follows:

[0045] Place the ITO bottom electrode 2 obtained in step 2) into the chamber and evacuate to 2×10⁻⁶. -4 Pa, using Ta (99.95%) as the sputtering target, crystalline TaO with a main crystal orientation of (100) and a maximum grain size of 30 nm was prepared on the bottom electrode obtained in step 2) by radio frequency reactive magnetron sputtering. x Thin film 3 is used as the resistive layer. The target and substrate spacing is 60 mm. The RF reactive sputtering power is 100 W, the sputtering pressure is 1.6 Pa, the deposition and crystallization temperature is 750 °C, the oxygen flow rate in the sputtering atmosphere is 10 sccm, the argon flow rate is 30 sccm, the purity of the working gas argon and the reactive gas oxygen is 99.999%, the deposition time is 30 min, and the deposition thickness is 180 nm.

[0046] The ultra-high crystallinity ITO bottom electrode and TaO prepared in this embodiment x See the XRD diffraction pattern of the thin film. Figure 3 .

[0047] In this embodiment, crystalline TaO was fabricated. x The current-voltage curve of a resistive random access memory is as follows: Figure 6 As shown in (a), its storage window is as follows Figure 6 As shown in (b), it can be seen from the figure that the resistance switching effect of this resistive switching device is also significant, the resistance switching characteristics are also obvious, the turn-on voltage is 3.0V, the resistance switching performance is excellent and the power consumption is low.

[0048] Example 5

[0049] Same as Example 1, except that step 3) is as follows:

[0050] Place the ITO bottom electrode 2 obtained in step 2) into the chamber and evacuate to 2×10⁻⁶. -4 Pa, using Ta (99.95%) as the sputtering target, crystalline TaO with a main crystal orientation of (100) and a maximum grain size of 30 nm was prepared on the bottom electrode obtained in step 2) by radio frequency reactive magnetron sputtering. x Thin film 3 is used as the resistive layer. The target and substrate spacing is 60 mm. The RF reactive sputtering power is 100 W, the sputtering pressure is 1.6 Pa, the deposition and crystallization temperature is 750 °C, the oxygen flow rate in the sputtering atmosphere is 12 sccm, the argon flow rate is 28 sccm, the purity of the working gas argon and the reactive gas oxygen is 99.999%, the deposition time is 30 min, and the deposition thickness is 180 nm.

[0051] In this embodiment, crystalline TaO was fabricated. x The current-voltage curve of a resistive random access memory is as follows: Figure 7 As shown in (a), its storage window is as follows Figure 7 As shown in (b), it can be seen from the figure that the resistance switching effect of this resistive switching device is also significant, the resistance switching characteristics are also obvious, the turn-on voltage is 2.1V, the power consumption is very low, and the process of the device switching from low resistance to high resistance shows a gradual trend.

[0052] Table 1 below shows the TaO content of Embodiments 1-5 of the present invention. x The oxygen-tantalum atom ratio of the resistive layer.

[0053] Table 1

[0054]

[0055] Table 2 shows a comparison of the electrical performance of Examples 3-5 of the present invention.

[0056] Table 2

[0057]

[0058] As can be seen from Tables 1 and 2, with the continuous increase of oxygen partial pressure, the entire TaO... x The ratio of oxygen to tantalum atoms in the device structure is also continuously increasing. When the oxygen partial voltage is less than 20%, the resistance in the resistive switching device changes gradually, and the high and low resistance values ​​are relatively close. However, when the oxygen partial voltage reaches 20%, the device exhibits a resistance of 10 at 8.7V. 5 The order-of-magnitude on / off ratio indicates an extremely high storage window. As the oxygen partial pressure continues to increase, the resistance on / off ratio decreases significantly, to 10. 3 The difference is orders of magnitude, but the switching voltage is also significantly reduced.

[0059] Comparative Example 1

[0060] 1) Cut a 4-inch (100) oriented single-crystal Si wafer into 1×1cm pieces. 2 The Si substrate was then ultrasonically cleaned in acetone, anhydrous ethanol and deionized water for 25-30 min in sequence, and finally dried with nitrogen.

[0061] 2) Place the substrate treated in step 1) into the chamber and evacuate to 2×10⁻⁶. -4Pa, using Ta (99.95%) as the sputtering target, a Ta thin film was prepared on the substrate obtained in step 1) by magnetron sputtering. Common Ta thin films were prepared under the conditions of DC reaction power of 40 W, sputtering gas pressure of 1 Pa, deposition temperature of room temperature, and oxygen concentration of 0% in the sputtering atmosphere. The Ta electrode thin films used in Examples 1 to 5 were prepared under the conditions of DC reaction power of 40 W, sputtering gas pressure of 1 Pa, deposition temperature of 750 °C, and oxygen concentration of 0% in the sputtering atmosphere.

[0062] This comparative example shows two Ta films deposited at different temperatures. The current-voltage curves of common Ta films are shown below. Figure 8 As shown in (a), the current-voltage curves of the Ta electrode films used in Examples 1-5 are as follows: Figure 8 As shown in (b), it can be seen from the figure that the Ta electrode film used in Examples 1 to 5 has a clear resistance switching behavior, while the common Ta film does not exhibit any resistance switching behavior. Therefore, the Ta electrode film used in Examples 1 to 5 can greatly improve the resistance switching performance of the resistive switching memory device with it as the top electrode.

[0063] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A crystalline TaO with ultra-high memory window x A method for manufacturing a resistive random access memory, characterized in that, The steps are as follows: Step one. Processing (100) oriented single crystal Si substrate, specifically including: cutting 4-inch (100) oriented single crystal Si wafer into 1 x 1 cm 2 Si substrates, then sequentially ultrasonic cleaning in acetone, anhydrous ethanol and deionized water for 25-30 min, and finally blowing dry with nitrogen; Step two. A (222) oriented ITO film is prepared on the substrate obtained in step one by a magnetron sputtering method as a bottom electrode, and the specific process parameters include: 80 W of radio frequency reaction sputtering power, 1 Pa of sputtering pressure, 500 ℃ of deposition temperature, and 15% of oxygen concentration in the sputtering atmosphere; Step three. The crystalline TaO with the maximum crystal size of 30 nm and the main crystal direction of (100) is grown on the ITO bottom electrode obtained in step two by the radio frequency reactive magnetron sputtering method x The thin film is used as a resistance layer, and the specific process parameters include: a deposition and crystallization temperature of 750℃, a radio frequency reactive sputtering power of 100W, a sputtering pressure of 1.6 Pa, and an oxygen concentration in the sputtering atmosphere ranging from 10% to 30%. Step four. The crystalline TaO obtained in step three is annealed at 750 ℃ for 1 h in an oxygen atmosphere x A Ta electrode is deposited on the resistance layer by a magnetron sputtering method, a direct current reaction power is 40 W, a sputtering pressure is 1 Pa, a deposition temperature is 750 ℃, and an oxygen concentration in a sputtering atmosphere is 0%, so that a crystalline TaO with an ultrahigh storage window is obtained x Resistive random access memory.

2. A crystalline TaO with ultra-high memory window according to claim 1 x A method for manufacturing a resistive random access memory, characterized by, The sputtering target in the magnetron sputtering method in the second step is an ITO target with a purity of 99.95%, the pressure in the chamber is 2x10 -4 The pressure in the chamber is 2x10 The pressure in the chamber is 2x10 3. The crystalline TaO with ultra-high memory window of claim 1 x A method for manufacturing a resistive random access memory, characterized by, The sputtering target in the radio frequency reaction magnetron sputtering method in the third step is a Ta target with a purity of 99.95%, the pressure in the chamber is 2×10 -4 Pa, the distance between the target and the substrate is 60 mm, the purity of the working gas argon and the reaction gas oxygen is 99.999%, the total amount of gas in the chamber is set to 40 sccm, and the crystalline TaO x The deposition time of the thin film is 30 min, and the deposition thickness is 180 nm.

4. The crystalline TaO with ultra-high memory window of claim 1 x A method for manufacturing a resistive random access memory, characterized in that, The sputtering target material is Ta target with purity of 99.95%, the chamber pressure is 2×10 -4 Pa, the target and substrate distance is 60 mm, the purity of the working gas argon and the reaction gas oxygen is 99.999%, the total amount of gas in the chamber is set to 40 sccm, the deposition time of the Ta electrode is 10 min, and the deposition thickness is 60 nm.

5. The crystalline TaO with ultra-high memory window of claim 1 x A method for manufacturing a resistive random access memory, characterized in that, In the step four, when depositing the Ta electrode by the magnetron sputtering method, a metal mask plate is attached to the TaO x The surface of the resistance layer, the deposited Ta electrode is in a cylindrical shape.

6. A crystalline TaO with ultra-high memory window prepared by the method of any one of claims 1-5 x Resistive random access memory.

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