CN106449973A - Flexible resistive random access memory and preparing metod thereof - Google Patents

Abstract

The invention discloses a flexible resistive random access memory. The flexible resistive random access memory structurally comprises a mica flexible substrate, an InGaZnO bottom electrode film layer, a ZrHfO dielectric film layer and a TiN top electrode film layer from bottom to top. The invention further discloses a preparing method of the resistive random access memory. The preparing method comprises the steps of adopting a mica material with a certain thickness as a flexible substrate to form the InGaZnO bottom electrode film layer, the ZrHfO dielectric film layer and the TiN top electrode film layer in sequence on the flexible substrate with a magnetron sputtering method. The flexible resistive random access memory has the advantages of being simple in structure, novel and unique in substrate, small in size, easy to bend, fast to read and write, resistant to high temperature and corrosion, high in bending resistance and the like. The flexible resistive random access memory is stable in storage performance, low in cost, high in density, high in operation speed, low in power consumption, strong in fatigue resistance and wide in application prospect, and is applicable to use and popularization in different kinds of electronic equipment.

Description

A kind of flexible resistive memory and preparation method thereof

technical field

The invention relates to a storage device and a preparation method thereof, in particular to a flexible resistive variable memory and a preparation method thereof.

Background technique

In recent years, with the continuous shrinking of the size of electronic equipment and the continuous enhancement of data processing capabilities, the resistive variable memory with continuously shrinking volume, high density, high speed and low power consumption has become the development trend of a new generation of memory.

Resistive RAM (RRAM) is a next-generation non-volatile memory based on the reversible switching between high and low resistance states by the resistance of non-conductive materials under the action of an external electric field. As early as 1967, someone studied the resistance transition of the Au/SiO/Al structure. Due to the influence of various factors such as experimental means and requirements, in 2000, someone studied the conversion characteristics of oxide film resistors. Structurally speaking, the resistive variable memory is a typical "sandwich" structure, and the top and bottom are resistive materials that can be switched. It can change the resistance of the device from high resistance to low resistance under the action of external bias voltage. Since the advantages of RRAM can just overcome the problem of charge leakage caused by the thinning of the oxide film in Flash, RRAM at a node below 32nm may replace Flash memory in the future.

In recent years, with the continuous development of flexible electronics, flexible electronic devices have attracted widespread attention due to their light weight, convenience and good mechanical properties. Then, under the premise of the rapid development of flexible electronic technology, realizing the flexibility of RRAM will be of great significance to broaden the application of RRAM. At present, there have been some research reports on PET flexible RRAM in the industry. However, due to the limited high temperature resistance of PET flexible substrates, the resistive switching layer must be prepared and used at low temperature. In addition, the prepared flexible RRAM has After repeated bending, it is easy to make the resistance change stability worse and even lose the resistance change performance, and there are also problems such as poor flexibility, not easy to bend, limited high temperature resistance, and poor corrosion resistance.

Contents of the invention

The purpose of the present invention is to provide a flexible resistive variable memory and its preparation method to solve the problem that the existing flexible resistive variable memory has limited high temperature resistance of the flexible substrate, which leads to the fact that its resistive variable conversion layer must be prepared and used at low temperature. In the secondary bending, the stability of the resistance value transition becomes poor and even the resistance switching performance is lost.

The purpose of the present invention is achieved through the following technical solutions: a flexible resistive variable memory, its structure from bottom to top is: mica flexible substrate, InGaZnO bottom electrode film layer, ZrHfO dielectric film layer and TiN top electrode film layer.

The thickness of the ZrHfO dielectric film layer is 3-8nm.

The thickness of the InGaZnO bottom electrode film layer is 60-190 nm, preferably 150-190 nm.

The thickness of the TiN top electrode film layer is 40nm-150nm.

The thickness of the mica flexible substrate is 0.01-0.04mm.

The present invention also provides a method for preparing a flexible resistive memory, comprising the following steps:

(a) Fix the mica flexible substrate on the substrate table in the chamber of the magnetron sputtering equipment, place the InGaZnO target and the ZrHfO target on the two target tables respectively, and vacuum the chamber to 1×10 ^-4 ~4×10 ^-4 Pa; Introduce 25~50sccm Ar into the chamber, adjust the gate valve to maintain the pressure in the chamber at 0.1~3Pa, turn on the RF source to control the ignition of the InGaZnO target, and adjust the RF source The power is 180~220W, the pressure is 0.2~1.5Pa, make the InGaZnO target glow, pre-sputter for 7~13min, open the baffle of the InGaZnO target and sputter for 17~23min, and form an InGaZnO bottom on the mica flexible substrate. Electrode film layer to obtain a composite structure of mica flexible substrate/InGaZnO bottom electrode film layer;

(b) Close the baffle of the InGaZnO target, re-evacuate to 1×10 ^-4 ~4×10 ^-4 Pa, feed 10~40sccm O ₂ and 20~70sccm Ar, and adjust the gate valve to make the pressure in the cavity Keep it at 2~7Pa, turn on the RF source that controls the ZrHfO target ignition, adjust the RF source power to 50~100W, and the pressure 1~5Pa; make the ZrHfO target glow, pre-sputter for 7~13min; open the ZrHfO target block The plate is formally sputtered for 28~33 minutes, and a ZrHfO dielectric film layer is formed on the InGaZnO bottom electrode film layer on the mica flexible substrate, and a composite structure of mica flexible substrate/InGaZnO bottom electrode film layer/ZrHfO dielectric film layer is obtained;

(c) Close the baffle of the ZrHfO target, close the radio frequency source, gas filling valve, gate valve, open the cavity of the magnetron sputtering equipment, and form the InGaZnO bottom electrode film layer and the ZrHfO dielectric film layer on the mica flexible substrate Place the mask plate and fix it on the substrate table of the cavity of the magnetron sputtering equipment; vacuumize the cavity to 1×10 ^-4 ~4×10 ^-4 Pa, pass 20~30sccm of Ar into the cavity, Keep the pressure in the chamber at 0.1~3Pa, turn on the DC source, adjust the power of the DC source to 13~17W, and the pressure to 0.5~1Pa to make the TiN target glow, pre-sputtering for 7~13min; formal sputtering for 55~65min , forming a TiN top electrode film layer on the ZrHfO dielectric film layer, and obtaining a flexible resistive variable memory with a composite structure of mica flexible substrate/InGaZnO bottom electrode film layer/ZrHfO dielectric film layer/TiN top electrode film layer.

The present invention provides that the mica flexible substrate described in step (a) of the preparation method can be thinned to an ideal thickness by knife cutting and tape sticking. The bendable property of flexible substrates.

The invention provides that the thickness of the InGaZnO bottom electrode film layer in the step (a) of the preparation method is 60-190 nm; preferably 150-190 nm.

The invention provides that the thickness of the ZrHfO dielectric film layer in the step (b) of the preparation method is 3-8 nm.

Circular holes with a diameter of 60-300 μm are evenly distributed on the mask plate described in step (c) of the preparation method provided by the present invention.

The TiN top electrode film layer described in step (c) of the preparation method provided by the present invention includes several circular electrodes with a diameter of 60-300 μm uniformly distributed on the ZrHfO dielectric film layer; the thickness thereof is 40-150 nm.

The InGaZnO target material, ZrHfO target material and TiN target material used in the present invention are commercially available.

The present invention selects the mica material of appropriate thickness as the flexible substrate, and sequentially forms the InGaZnO bottom electrode film layer, the ZrHfO dielectric film layer and the TiN top electrode film layer on the mica flexible substrate by the method of magnetron sputtering, and obtains high Density flexible resistive memory. In the present invention, the mica material with a high temperature resistance of up to 1500°C is selected as the flexible substrate, and the flexible substrate also has the characteristics of strong corrosion resistance, high toughness, small volume, and easy bending. It is applied to various Flexible electronic devices have a positive role in promoting the development of industry technology. The resistive variable memory provided by the present invention exhibits a relatively stable change in resistance value, the distribution of resistance values in high and low resistance states is very concentrated, and there is a large difference between high resistance value and low resistance value, so it is not easy to cause high and low resistance values. The resistance value is confused, and it is not easy to cause misreading when reading data; after repeated bending, the resistance value change can be controlled within a small fluctuation range, and the performance is very stable. In addition, the flexible resistive memory provided by the present invention has a significant switching effect, and the memory performs excellent in fatigue resistance tests both in the high-resistance state and the low-resistance state.

In short, the flexible resistive memory provided by the present invention has good performances such as simple structure, novel and unique substrate, small size, easy bending, fast reading and writing data, high temperature resistance, corrosion resistance, and strong bending resistance. , low cost, high density, fast operation speed, low power consumption, strong fatigue resistance, broad application prospects flexible resistive memory, suitable for popularization and use in various electronic devices.

Description of drawings

FIG. 1 is a schematic structural view of the flexible resistive memory provided by the present invention.

Fig. 2 is a schematic structural diagram of the magnetron sputtering equipment used in the preparation of the flexible resistive memory in Example 2.

FIG. 3 is a voltage-current characteristic diagram of the flexible resistive memory manufactured in Example 2. FIG.

FIG. 4 is a graph showing HRS and LRS retention characteristics of the flexible resistive memory manufactured in Example 2. FIG.

FIG. 5 is a graph showing the bending characteristics of the flexible resistive variable memory manufactured in Example 2. FIG.

detailed description

The following examples are used to further describe the present invention in detail, but the examples do not limit the present invention in any form. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the technical field. But it does not limit the present invention in any form.

Example 1

The structure of the flexible resistive memory prepared by the present invention is shown in Figure 1, including the bottom mica flexible substrate 1, an InGaZnO bottom electrode film layer 2 grown on the mica flexible substrate 1 by magnetron sputtering, A ZrHfO dielectric film layer 3 grown on the InGaZnO bottom electrode film layer 2 , and a TiN top electrode film layer 4 grown on the ZrHfO dielectric film layer 3 .

The thickness of the mica flexible substrate 1 is 0.01-0.04 mm, preferably 0.02 mm. In actual use, the mica sheet can be thinned to an ideal thickness by methods such as knife cutting and tape sticking.

Wherein the thickness of the ZrHfO dielectric film layer 3 is 3-8nm, preferably 5nm; the thickness of the InGaZnO bottom electrode film layer 2 is 60-190nm, preferably 150-190nm, more preferably 170nm;

The TiN top electrode film layer 4 includes a number of circular electrodes with a diameter of 200 μm uniformly distributed on the ZrHfO dielectric film layer 3 ; the thickness thereof is 40 nm to 150 nm, preferably 40 nm.

Example 2

The preparation method of the resistive memory provided by the present invention comprises the following steps:

(1) Using the magnetron sputtering equipment shown in 2, two target stages 5 are arranged below the substrate stage 7 in the cavity 9, and the upper parts of the target stages 5 are respectively placed with targets 6; turn on the magnetron sputtering In the cavity 9 of the irradiation equipment, the mica flexible substrate with a thickness of 0.02 mm is first placed on the substrate support 8 and fixed on the substrate table 7 in the cavity 9, and the InGaZnO target and the ZrHfO target are respectively placed on two On a target stage 5, close the cavity 9 after fixing it, and evacuate the cavity 9 and the gas path to 2×10 ^-4 Pa; pass 25 sccm of Ar into the cavity through the inflation valve 11, and adjust the gate valve 10 so that The pressure in the cavity 9 is maintained at 0.5Pa, and the radio frequency source that controls the ignition of the InGaZnO target is turned on, the power of the radio frequency source is adjusted to 200W, and the pressure is 0.5Pa, so that the InGaZnO target is illuminated, and the pre-sputtering is performed for 10 minutes; after the pre-sputtering, Open the InGaZnO target baffle and start sputtering for 20 minutes to form the first layer of InGaZnO bottom electrode film with a thickness of 170nm on the mica flexible substrate;

(2) Close the baffle plate of the InGaZnO target, and re-evacuate to 2×10 ^-4 Pa, and feed 25 sccm O ₂ and 50 sccm Ar through the gas filling valve 11 to maintain the pressure in the cavity at 3 Pa, and open the control ZrHfO target For the starting radio frequency source, adjust the power of the radio frequency source to 80W and the pressure to 3Pa; make the ZrHfO target material glow, and pre-sputter for 10 minutes; A ZrHfO dielectric film layer with a thickness of 5 nm is formed on the InGaZnO bottom electrode film layer;

(3) Close the baffle of the ZrHfO target material, close the radio frequency source, the gas filling valve 11, and the gate valve 10, open the cavity 9 of the magnetron sputtering equipment, take out the mica flexible substrate that has been coated with two layers of films, and place it in the ZrHfO A mask is placed on the dielectric film, and circular holes with a diameter of 200 μm are evenly distributed on the mask. After the growth of the electrode film is completed, the size of these circular holes is the size of the effective working area of the memory; and the substrate is taken out The bottom platform 8 is polished with sandpaper until it shines, and the polished waste and organic matter attached to the surface are cleaned with acetone, and finally wiped clean with alcohol, and the processed substrate platform 8 is placed into the substrate holder 7 in the cavity 9 After fixing, close the chamber 9, vacuumize the chamber 9 of the magnetron sputtering equipment to 2×10 ^-4 Pa through the mechanical pump and the molecular pump, pass 25 sccm Ar into the chamber, and adjust the gate valve 10 Keep the pressure in the cavity at 0.8Pa, turn on the DC source, adjust the power of the DC source to 15W, and the pressure to 0.8Pa to make the TiN target glow, pre-sputter for 10 minutes, and formally sputter for 60 minutes to form a thickness of A resistive variable memory with a composite structure of mica flexible substrate/InGaZnO bottom electrode film layer/ZrHfO dielectric film layer/TiN top electrode film layer was obtained.

The above-mentioned implementation mode is any embodiment of the preparation method protected by the present invention, and those skilled in the art can obtain the following parameters according to the claims and the scope of the process parameters described in the description (mica flexible substrate thickness, its magnetic controlled sputtering chamber vacuum degree, RF source power, pre-sputtering time and official sputtering time, etc.), the flexible resistive memory to be protected in Embodiment 1 of the present invention can be obtained, and the prepared flexible resistive memory and The devices prepared in this example have basically similar properties.

Embodiment 3 performance test

The current-voltage characteristic curve was measured by applying the scanning voltage to the flexible resistive memory prepared in Example 2, and the results are shown in FIG. 3 . As shown in Figure 3, a positive voltage is applied to the TiN electrode of the resistive switching element prepared in Example 2. When the voltage reaches the turn-on voltage (Set Voltage), the resistive switching element changes from a high-resistance state to a low-resistance state (1→ 2), as the scan voltage decreases to the positive turn-off voltage (Reset Voltage), the resistance value of the resistive variable element changes from a low resistance state to a high resistance state (3→4), and the same is true when the reverse scan voltage is applied .

By testing the retention characteristics of the high resistance state and low resistance state of the flexible substrate varistor prepared in Example 2, the results are shown in Figure 4. The high resistance state (order of magnitude is 10 ⁹ ) and the low resistance state (order of magnitude At 10 ⁶ ), the characteristics are very stable under a long-term test with a duration of more than 10 ⁴ seconds. The ratio of the high-resistance state to the low-resistance state exceeds 10 ³ orders of magnitude. It has very good resistance-change characteristics and is not prone to misreading.

The flexible substrate varistor prepared in Example 2 was tested for high and low configurations after 1000 times of bending, and the results are shown in Figure 5. It can be maintained in a relatively small range of changes, indicating that the resistive variable element has flexible and bendable properties. This feature has broad application prospects in future electronic devices.

The above-mentioned embodiment is a preferred embodiment of the present invention, but the embodiment of the present invention is not limited by the embodiment, and any other changes, modifications, substitutions and combinations made without departing from the spirit and principle of the present invention , simplification, all should be equivalent replacement methods, and are all included in the protection scope of the present invention.

Claims (10)

1. a kind of flexibility resistance-variable storing device is it is characterised in that its structure is followed successively by from top to bottom：Muscovitum flexible substrate, InGaZnO Hearth electrode film layer, ZrHfO media coating and TiN top electrode film layer.

2. flexibility resistance-variable storing device according to claim 1 is it is characterised in that the thickness of described ZrHfO media coating is 3 ~8nm.

3. flexibility resistance-variable storing device according to claim 1 is it is characterised in that the thickness of described InGaZnO hearth electrode film layer Spend for 60 ~ 190nm.

4. flexibility resistance-variable storing device according to claim 1 is it is characterised in that the thickness of described TiN top electrode film layer is 40nm~150nm.

5. the flexible resistance-variable storing device according to claim 1,2,3 or 4 is it is characterised in that described Muscovitum flexible substrate Thickness is 0.01 ~ 0.04mm.

6. a kind of preparation method of flexibility resistance-variable storing device is it is characterised in that comprise the following steps：

（a）Muscovitum flexible substrate is fixed on the substrate table in magnetron sputtering apparatus cavity, by InGaZnO target and ZrHfO Target is individually placed on two target platforms, and cavity is evacuated to 1 × 10^-4~4×10^-4Pa；It is passed through 25 ~ 50sccm into cavity Ar, adjustment slide valve make the pressure in cavity maintain 0.1 ~ 3Pa, open control InGaZnO target build-up of luminance radio frequency source, adjust Whole RF source power is 180 ~ 220W, pressure 0.2 ~ 1.5Pa, makes InGaZnO target build-up of luminance, pre-sputtering 7 ~ 13min, opens The baffle plate formal sputtering 17 ~ 23min of InGaZnO target, in the upper formation InGaZnO hearth electrode film layer of Muscovitum flexible substrate, obtains Composite construction to Muscovitum flexible substrate/InGaZnO hearth electrode film layer；

（b）Close the baffle plate of InGaZnO target, be again evacuated to 1 × 10^-4~4×10^-4Pa, is passed through 10 ~ 40sccm O₂With 20 ~ 70sccm Ar, adjustment slide valve makes the pressure in cavity maintain 2 ~ 7Pa, opens the radio frequency source controlling ZrHfO target build-up of luminance, Adjustment RF source power is 50 ~ 100W, pressure 1 ~ 5Pa；Make ZrHfO target build-up of luminance, pre-sputtering 7 ~ 13min；Open ZrHfO target Baffle plate formal sputtering 28 ~ 33min, forms ZrHfO media coating in the InGaZnO hearth electrode film layer in Muscovitum flexible substrate, Obtain the composite construction of Muscovitum flexible substrate/InGaZnO hearth electrode film layer/ZrHfO media coating；

（c）Close the baffle plate of ZrHfO target, close radio frequency source, charge valve, slide valve, open the cavity of magnetron sputtering apparatus, Formed and place mask plate in InGaZnO hearth electrode film layer and the Muscovitum flexible substrate of ZrHfO media coating, be fixed to magnetron sputtering On the substrate table of equipment cavity；Cavity is evacuated to 1 × 10^-4~4×10^-4Pa, is passed through the Ar of 20 ~ 30sccm into cavity, Make the pressure in cavity maintain 0.1 ~ 3Pa, open DC source, the power of adjustment DC source is 13 ~ 17W, pressure 0.5 ~ 1Pa, Make TiN target build-up of luminance, pre-sputtering 7 ~ 13min；Formal sputtering 55 ~ 65min, forms TiN top electrode film on ZrHfO media coating Layer, has obtained Muscovitum flexible substrate/InGaZnO hearth electrode film layer/ZrHfO media coating/TiN top electrode film layer composite construction Flexible resistance-variable storing device.

7. the preparation method of flexibility resistance-variable storing device according to claim 6 is it is characterised in that step（a）Described cloud The thickness of female flexible substrate is 0.01 ~ 0.04mm.

8. the preparation method of flexibility resistance-variable storing device according to claim 1 is it is characterised in that step（a）Described The thickness of InGaZnO hearth electrode film layer is 60 ~ 190nm.

9. the preparation method of flexibility resistance-variable storing device according to claim 1 is it is characterised in that step（b）Described ZrHfO The thickness of media coating is 3 ~ 8nm.

10. the preparation method of flexibility resistance-variable storing device according to claim 1 is it is characterised in that step（c）Described TiN The thickness of top electrode film layer is 40nm ~ 150nm.