KR20090001397A - Method for recording resistance switching element, method for manufacturing resistance switching element and resistance switching element having the same - Google Patents

Abstract

The method for recording resistance switching element, the method for manufacturing resistance switching element and the resistance switching element having the same are provided to shorten the resistance switching time and to improve the speed of device by using the anode plate resistance switching characteristic. The resistance switching element comprises the bottom electrode(120), the transition metal oxide thin film(130) formed on the bottom electrode and the upper electrode(140) formed in the transition metal oxide thin-film. In the information recording method of the resistance switching element, the anode plate resistance switching forming is performed on the transition metal oxide thin film to obtain the bipolar resistance switching, BRS property by applying voltage o the transition metal oxide thin film. The voltage that is lower than the set voltage of USR and higher than the soft set voltage is applied to the forming transition metal oxide thin film. The resistance of the transition metal oxide thin film is changed.

Description

Information recording method of resistance change recording element, manufacturing method of resistance change recording element and resistance change recording element using same {Method for recording resistance switching element, method for manufacturing resistance switching element and resistance switching element having the same}

1 is a voltage-current diagram showing unipolar resistance switching (URS) characteristics,

2 is a flowchart illustrating a process of performing a preferred embodiment of the method for manufacturing a resistance change recording device according to the present invention;

3 is a view showing a schematic structure of a preferred embodiment of a resistance change recording element according to the present invention;

4 is a flowchart showing a process of performing a preferred embodiment of the information recording method of the resistance change recording element according to the present invention;

5 is a voltage-current diagram showing a soft set of bipolar resistance switching (BRS);

6 is a voltage-current diagram showing anode resistance switching characteristics;

FIG. 7 is a voltage-current diagram showing the voltage and current of FIG. 6 on a logarithmic scale;

8 is a flowchart showing a process of performing another preferred embodiment of the information recording method of the resistance change recording element according to the present invention;

9 is a voltage-current diagram showing a second anode resistance switching characteristic,

10 is a voltage-current diagram showing both the first anode resistance switching characteristic and the second anode resistance switching characteristic;

FIG. 11 is a voltage-current diagram illustrating the voltage and current of FIG. 10 on a logarithmic scale.

The present invention relates to a resistance change recording device, and more particularly, to an information recording method of a resistance change recording device using a bipolar resistance switching (BRS) characteristic, a method of manufacturing a resistance change recording device, and a resistance using the manufacturing method. A change recording device.

Recently, due to the remarkable development of the information and communication industry, the demand for various memory devices is increasing. In particular, memory devices required for portable terminals, MP3 players and the like are required to be nonvolatile, in which recorded data is not erased even when the power is turned off. Such nonvolatile memory devices can be electrically stored and erased, and data can be stored even when power is not supplied. Therefore, their applications are increasing in various fields. However, the conventional dynamic random access memory (DRAM) constructed by using a semiconductor has a volatile characteristic that loses all stored information when power is not supplied. Research is being done.

Among these nonvolatile memory devices, phase transition random access memory (phase RAM, PRAM) using phase transition phenomenon, magnetic random access memory (magnetic RAM, MRAM) using magnetoresistance change phenomenon, ferroelectric random access memory using spontaneous polarization phenomenon of ferroelectric In addition to (ferroelectric RAM, FRAM), a resistance change recording device (resistance RAM, ReRAM) using the resistance switching or conductivity switching of the metal oxide thin film is the subject of research. In particular, ReRAM has attracted much attention recently because of its very simple device structure and relatively simple manufacturing process compared with other nonvolatile memory devices.

ReRAM is a metal-oxide-metal (MOM) basic device structure that changes from a high resistance state (HRS) to a low resistance state (LRS) when an appropriate electrical signal is applied. Will appear. In other electrical signals, the low resistance state is changed to a high resistance state. Through this switching phenomenon, the information is recorded and read.

In order to realize a good ReRAM, the ratio of the resistance value of the high resistance state to the resistance value of the low resistance state must be large, and the driving voltage must be small to reduce the power consumption of the entire memory. In addition, the data retention function should be excellent to keep the recorded information for a long time, and the endurance should be excellent even for a large number of switching for repeated recording. In addition, the switching time must be short for fast operation. That is, it should exhibit excellent resistance switch characteristics. To this end, research on unipolar resistance switching (URS) characteristics among resistance switch characteristics has been made.

1 is a voltage-current diagram showing a single-pole resistance switching characteristic.

In FIG. 1, a resistive change recording device is constructed by using a TiO ₂ thin film as an oxide and a Pt electrode as an upper and lower electrode. The newly formed TiO ₂ thin film is in a high resistance state as an insulating film. The TiO ₂ thin film has little current and no resistance change even when the voltage is increased. Therefore, in order to exhibit resistance change characteristics, it is necessary to first make a state in which resistance change is possible. Making such a change in resistance possible is called forming. Forming to exhibit a unipolar resistance switching characteristic is to apply a voltage (V _f ) that breakdown occurs to the freshly formed TiO ₂ thin film corresponds to the reference numeral 10 of FIG. At this time, by applying a compliance current (I _c ), it is necessary to apply a constraint so that the current flowing through the TiO ₂ thin film does not flow more than the compliance current. This causes excessive current to flow without applying the compliance current I _c while applying the voltage V _{f at} which the breakdown occurs, and the insulating property is destroyed again and is not recovered.

After such forming, voltage sweep in a positive direction from 0V causes a current increase as shown by the solid line 20 in FIG. 1, indicating that the TiO ₂ thin film is in a low resistance state. . During the voltage sweep, it can be seen that if a specific voltage or more is applied, the current rapidly decreases (40), thereby dramatically increasing the resistance of the TiO ₂ thin film. This particular voltage is referred to as the monopole resistance switching reset voltage (V _URSreset ). Subsequently, when the voltage is swept again from 0 V, almost no current flows as shown by the solid line 30 in FIG. 1. That is, the TiO ₂ thin film is changed to a high resistance state.

If the voltage applied to the TiO ₂ thin film in the high resistance state is continuously increased, a current jump appears at another specific voltage larger than the monopolar resistance switching reset voltage V _URSreset (50). . This other specific voltage is called the monopole resistance switching set voltage (V _URSset ). If the voltage is gradually increased again from 0 V after such a current jump, current flows again as shown by the solid line 20 of FIG. 1, and the TiO ₂ thin film is changed back to a low resistance state.

That is, the set voltage means a voltage for changing an oxide in a high resistance state to a low resistance state, and on the contrary, the reset voltage is defined as a voltage for changing an oxide in a low resistance state to a high resistance state. The set and reset voltages of the phases follow this definition.

As a result, the voltage sweep after the foaming enables reproducible switching between low and high resistance states. The resistance switching characteristics shown in FIG. 1 occur in both a positive voltage and a negative voltage, regardless of the polarity of the voltage. Therefore, such resistance switching is called unipolar resistance switching. That is, the single-pole resistance switching characteristic has a characteristic of switching between a low resistance state and a high resistance state by applying only one polarity irrespective of the polarity of the applied voltage.

If the ReRAM is implemented by using the single-pole resistance switching characteristic, the resistance difference between the low resistance state and the high resistance state is very large, which is advantageous for reading the device in which the information is recorded. There is a problem that consumption occurs. In addition, in order to switch from the low resistance state to the high resistance state, or from the high resistance state to the low resistance state, it is preferable to apply a pulse voltage. In the case of single-pole resistance switching, there is a problem in that the switching time is long. In particular, when applying a pulse voltage for the reset, there is a problem that takes a long time to switch from the high resistance state to the low resistance state. In addition, as the switching is repeated, there is a problem that the start voltage and the restart voltage are not constant and fluctuate.

An object of the present invention is to provide an information recording method of a resistance change recording device having a low driving voltage and low power consumption and a short switching time.

Another object of the present invention is to provide a resistance change recording device manufacturing method having a low power consumption and a short switching time due to a low driving voltage, and a resistance recording device using the manufacturing method.

In order to achieve the above technical problem, an information recording method of a resistance change recording device according to the present invention includes a structure of a lower electrode, a transition metal oxide thin film formed on the lower electrode, and an upper electrode formed on the transition metal oxide thin film. An information recording method of a resistance change recording device, comprising: applying a voltage to the transition metal oxide thin film to form a bipolar resistance switching (BRS) characteristic of the transition metal oxide thin film to exhibit bipolar resistance switching (BRS) characteristics step; Without a current applied to the formed transition metal oxide thin film, less than the set voltage of unipolar resistance switching (URS) of the transition metal oxide thin film, the magnitude of the soft set voltage Varying the resistance of the transition metal oxide thin film by applying a voltage having a greater mutually opposite polarity, respectively; And assigning "0" or "1" according to the resistance of the transition metal oxide thin film, wherein the softset voltage is applied to the transition metal oxide thin film by voltage sweep. In this case, the current is discontinuously increased at a voltage smaller than the set voltage of the single-pole resistance switching.

In order to achieve the above technical problem, another information recording method of the resistance change recording device according to the present invention includes a structure of a lower electrode, a transition metal oxide thin film formed on the lower electrode, and an upper electrode formed on the transition metal oxide thin film. An information recording method of a resistance change recording device comprising: forming a voltage of the transition metal oxide thin film to exhibit an anode resistance switching characteristic by applying a voltage to the transition metal oxide thin film; A voltage greater than the reset voltage of the first anode resistance switching and less than the set voltage of the unipolar resistance switching is applied to the formed transition metal oxide thin film, or greater than the reset voltage of the first anode resistance switching. After applying a voltage smaller than the set voltage of the single-pole resistance switching, and applying a voltage greater than the set voltage of the first positive-resistance switching and smaller than the set voltage of the single-pole resistance switching, or the set of the second positive-resistor switching. Varying the resistance of the transition metal oxide thin film by applying a compliance current that is greater than the magnitude of the voltage and less than the magnitude of the set voltage of unipolar resistance switching and limits the increase in current magnitude; And allocating "0", "1" or "2" according to the resistance of the transition metal oxide thin film, wherein the first anode resistance switching is an anode resistance switching in a state in which no current is applied. The second anode resistance switching may be a cathode resistance switching in a state in which a compliance current is applied to limit an increase in the magnitude of the current.

In the information recording method of the resistance change recording device according to the present invention, the anode resistance switching forming step includes: forming a single pole resistance switching so that the unipolar resistance switching characteristic appears on the transition metal oxide thin film; And applying a voltage to the transition metal oxide thin film formed so that the unipolar resistance switching characteristic is greater than the reset voltage of the unipolar resistance switching and smaller than the set voltage of the unipolar resistance switching.

In the information recording method of the resistance change recording element according to the present invention, the voltage applied to the step of changing the resistance may be a voltage in the form of a pulse.

In order to achieve the above technical problem, the resistance change recording device manufacturing method according to the present invention comprises the steps of forming a lower electrode; Forming a transition metal oxide thin film on the lower electrode; Forming an upper electrode on the transition metal oxide thin film; Unipolar resistance switching forming so that the unipolar resistance switching characteristic appears on the transition metal oxide thin film; And applying a voltage greater than the magnitude of the unipolar resistance switching reset voltage and less than the magnitude of the unipolar resistance switching set voltage to the transition metal oxide thin film formed to exhibit the unipolar resistance switching characteristic.

In order to achieve the above technical problem, the resistance translation recording device according to the present invention is manufactured by the above method.

According to the present invention, power consumption can be reduced by lowering the driving voltage of the resistance change recording element, and the writing speed of the resistance change recording element can be improved by shortening the switching time.

Hereinafter, exemplary embodiments of an information recording method of a resistance change recording device according to the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various forms, and only the present embodiments are intended to complete the disclosure of the present invention and to those skilled in the art to fully understand the scope of the invention. It is provided to inform you.

2 is a flowchart illustrating a process of carrying out a preferred embodiment of the method for manufacturing a resistance change recording device according to the present invention, and FIG. 3 is a schematic structure of the resistance change recording device according to the present invention manufactured by the method of FIG. It is a figure which shows.

2 and 3, first, the lower electrode 120 is formed on the substrate 110 (S210). The lower electrode 120 is formed of a thin film including at least one selected from Pt, Ru, Ir, Ag, Al, or TiN, and preferably, a thin film of Pt. The Pt thin film is formed using an e-beam evaporation method, and is formed of a thin film having a thickness of about 500 μs.

Next, the transition metal oxide thin film 130 is formed on the lower electrode 120 (S220). The transition metal oxide thin film 130 is composed of a single layer or a multi layer composed of at least one selected from TiO ₂ , NiO, HfO ₂ , Al ₂ O ₃ , ZrO _2, and ZnO. It is made of a TiO ₂ thin film. The TiO ₂ thin film is formed using a plasma enhanced atomic layer deposition (PEALD) method, and is formed as a thin film having a thickness of about 100 to 600 Å.

Next, the upper electrode 140 is formed on the transition metal oxide thin film 130 (S230). Like the lower electrode 120, the upper electrode 120 is made of a thin film including at least one selected from Pt, Ru, Ir, Ag, Al, or TiN, and preferably, a Pt thin film having a thickness of about 100 μs is formed. do. The upper electrode 140 is patterned by using a lift-off method.

Next, the transition metal oxide thin film 130 is formed to exhibit unipolar resistance switching characteristics (S240). As described above, the voltage corresponding to V _f of FIG. 1 is applied between the upper electrode 140 and the lower electrode 120 in a state in which a compliance current such as I _c of FIG. 1 is applied. Anode resistance switching is different from unipolar resistance switching, in which switching is performed by applying a voltage having a different polarity when changing from a high resistance state to a low resistance state and a polarity used when changing from a low resistance state to a high resistance state. it means. In order to form such a cathode resistance switching characteristic, first, the transition metal oxide thin film 130 is formed so as to exhibit a unipolar resistance switching characteristic to change from a high resistance state to a low resistance state.

Next, a voltage greater than the reset voltage of the unipolar resistance switching and smaller than the set voltage of the unipolar resistance switching is applied to the transition metal oxide thin film 130 (S250). This is to _{apply a} voltage between the upper electrode 140 and the lower electrode 130 that is greater than the voltage corresponding to V _URSreset of FIG. 1 and smaller than the voltage corresponding to V _URSset of FIG. 1. Through this process, the transition metal oxide thin film 130 is changed from a low resistance state to a high resistance state, and the transition metal oxide thin film 130 is in a state capable of switching anode resistance.

By the above method, the resistance change recording device according to the present invention can be manufactured.

4 is a flowchart showing a process of performing a preferred embodiment of the information recording method of the resistance change recording element according to the present invention.

Referring to FIGS. 3 and 4, first, as shown in FIG. 3, a resistance change recording device having a lower electrode 120, a transition metal oxide thin film 130, and an upper electrode 140 formed on a substrate 110 may be formed. 100) to prepare (S310).

Next, the transition metal oxide thin film 130 is formed to exhibit the anode resistance switching characteristic (S320). The method of forming the transition metal oxide thin film 130 to show the anode resistance switching characteristic may be performed through steps S240 and S250 of FIG. 2.

The resistance switching characteristics of the transition metal oxide thin film 130 formed by applying a positive voltage in step S320 will be described. In the case of forming by applying a negative voltage, only the opposite polarity is the same.

To this end, applying a voltage to the transition metal oxide thin film 130 formed by applying a positive voltage in step S320 and performing a voltage sweep in a negative direction at 0V, a voltage-current diagram as shown in FIG. 5 is obtained. Can be. After forming for the anode resistance switching, the transition metal oxide thin film 130 is in a high resistance state, so that little current flows at a small voltage as indicated by reference numeral 410. Then, when a certain voltage is reached, a current jump phenomenon in which the current suddenly increases greatly discontinuously appears (420). This phenomenon is different from the set of single-pole resistance switching, which is called a soft set, and a specific voltage corresponds to a soft set voltage (V _softset ). After this _softset voltage V _softset , even if the voltage is increased, the current change is insignificant as shown by reference numeral 430. When the voltage is increased to reach the set voltage V _{URSset of the} single-pole resistance switching, the single-pole resistance switching set will appear (440).

However, without increasing the voltage up to the set voltage (V _URSset ) of unipolar resistance switching, the voltage increase is stopped after reaching the _softset voltage (V _softset ), and a positive resistance switching characteristic appears when a voltage having a reverse polarity is applied. .

FIG. 6 is a voltage-current diagram showing the anode resistance switching characteristic, and FIG. 7 is a voltage-current diagram showing the voltage and current of FIG. 6 on a logarithmic scale.

6 and 7, the transition metal oxide thin film 130 uses a TiO ₂ thin film, and the upper electrode 140 and the lower electrode 130 constitute a resistance change recording device 100 using a Pt electrode. It was. 6 and 7, after forming the TiO ₂ thin film for anode resistance switching and performing a voltage sweep in the negative direction, as shown by reference numeral 530, there is almost no change in current at a small voltage. When the voltage is reached, a current jump appears (510). This corresponds to the softset described above. If the sweep continues after this particular voltage, the current decreases little by little.

If the voltage sweep is stopped before the unipolar resistance switching set appears and the voltage sweep is performed in the positive direction again at 0 V, an area with little current change appears at a small voltage as shown by reference numeral 550. However, as the voltage continues to increase, a current jump appears (520) when another specific voltage is reached. This also corresponds to the softset described above. Anode resistance switching is symmetrical in polarity of the applied voltage, so softsets appear one by one according to their polarity. Also in this case, the voltage sweep is stopped without increasing the voltage to the voltage at which the single-pole resistance switching set appears. If the voltage sweep is reversed up to 0V, the current change with the voltage becomes as shown by reference numeral 570. If the voltage sweep is continued in this manner, the above process is repeated.

7 clearly shows the difference between the current (-?-) Indicated by reference numeral 570 and the current (-?-) Indicated by reference numeral 550. FIG. Referring to FIG. 7, at 0.1 to 0.2 V, the current (-?-) Indicated by reference numeral 550 is about 6 × 10 ^-5 A, and the current (-■-) indicated by reference numeral 570 is about 2 × 10 ^-4 A to be. When this is changed to resistance, the state corresponding to reference number 570 corresponds to the low resistance state, and the state corresponding to reference number 550 corresponds to the high resistance state, and the resistance value of the high resistance state corresponds to the resistance value of the low resistance state. 2 to 10 times larger than.

That is, after the softset 510 appears in the negative voltage region, the curve 550 drawn corresponds to a high resistance state, and the curve 570 drawn after the softset 520 appears in the positive voltage region is shown. Corresponds to the low resistance state. That is, the soft set 520 appearing in the positive voltage region corresponds to the set because the high resistance state 550 is changed to the low resistance state 570, and the high resistance state 550 is changed to the low resistance state 570. The voltage to be changed is called the set voltage V _BRSset of the anode resistance switching. In addition, the softset 510 that appears in the negative voltage region corresponds to a reset because the low resistance state 570 is changed to the high resistance state 550, and the low resistance state 570 is changed to the high resistance state 550. The voltage to change is referred to as the positive resistance switch switching voltage (V _BRSreset ). That is, in the anode resistance switching characteristic, a voltage having a different polarity is applied to change the transition metal oxide thin film 130 from the low resistance state 570 to the high resistance state 550, or the low resistance state in the high resistance state 550. State 570 is to change the state.

Next, a voltage is applied to the formed transition metal oxide thin film 130 to switch the transition metal oxide thin film 130 to a low resistance state or a high resistance state (S330). In the actual driving of the device, as shown in FIGS. 6 and 7, it is preferable to drive the device by applying a pulse of a voltage that can be easily controlled, rather than performing a voltage sweep. When the transition metal oxide thin film 130 is in the high resistance state 550, a voltage greater than the set voltage V _BRSset of the anode resistance switching is applied (520) to bring the transition metal oxide thin film 130 into the low resistance state. 570. On the contrary, when the transition metal oxide thin film is in the low resistance state 570, a voltage smaller than the magnitude of the reset voltage V _BRSreset of the anode resistance switching is applied (510) to change the state of the transition metal oxide thin film 130 to the high resistance state. 550.

That is, to switch the transition metal oxide thin film 130 to the low resistance state 570, a voltage greater than the magnitude of the anode resistance switching set voltage V _BRSset is applied to the transition metal oxide thin film 130. In order to switch the transition metal oxide thin film 130 to the high resistance state 550, a voltage greater than the magnitude of the reset voltage V _BRSreset of the anode resistance switching is applied.

However, in all of the above cases, a voltage having a range greater than or equal to the set voltage of single-pole resistance switching corresponding to V _URSset of FIG. 5 should not be applied. When applying a voltage having a set voltage (V _URSset) size range than in unipolar resistance switching, and after that does not exhibit a positive resistance switching properties, exhibit a unipolar resistance switching characteristics because the set voltage (V _URSset) of the single-pole resistance switching Do not apply more than the magnitude of the voltage. If a voltage having a range greater than or equal to the unipolar resistance switching set voltage V _URSset is applied, the unipolar resistance switching reset voltage corresponding to V _URSreset of FIG. 1 is applied again to form a positive resistance switching characteristic.

4 again, “0” and “1” are allocated according to the resistance state of the transition metal oxide thin film 130 (S340). In general, the information is recorded by assigning a low resistance state with a large current to "1" and a high resistance state with a small current as "0".

In the above, the case where the information is recorded in two forms by using the resistance change recording element 100 has been described. Since the information is recorded in three forms, it helps to record a larger amount of information in various ways. In this section, we look at three cases of recording information.

8 is a flowchart showing another preferred embodiment of the information recording method of the resistance change recording element according to the present invention.

Referring to FIGS. 3 and 8, first, as shown in FIG. 3, a resistance change recording device having a lower electrode 120, a transition metal oxide thin film 130, and an upper electrode 140 formed on a substrate 110 may be formed. 100) to prepare (S710).

Next, the transition metal oxide thin film 130 is formed to exhibit the anode resistance switching characteristic (S720). The method of forming the transition metal oxide thin film 130 to show the anode resistance switching characteristic may be performed through steps S240 and S250 of FIG. 2.

In order to record information in three forms, in order to make the transition metal oxide thin film 130 have resistance values in three states, other methods besides the above-described switching method should be additionally used. First, the transition metal oxide thin film 130 may be changed into an intermediate resistance state and a high resistance state by the above-described switching method. Here, the intermediate resistance state corresponds to the low resistance state 570 of FIG. 6, and the high resistance state corresponds to the high resistance state 550 of FIG. 6. Therefore, in order to obtain a lower resistance state than the low resistance state 570 of FIG. To this end, while applying a _softset voltage corresponding to V _softset of FIG. 5 to the transition metal oxide thin film 130, a switching type of limiting the current jump occurs by applying a compliance current that restricts the increase in current. Method is used.

FIG. 9 is a voltage-current diagram illustrating anode resistance switching characteristics with other types of characteristics using compliance currents.

9, the transition metal oxide thin film 130 is formed of a TiO ₂ thin film, and the upper electrode 140 and the lower electrode 130 are formed of a resistance change recording device 100 using a Pt electrode. Referring to FIG. 9, first, a positive voltage is applied to change the reset state of the monopole resistance switching (this corresponds to the forming of the anode resistance switching as described above), and then when the voltage is swept in the negative direction at 0V. The compliance current I _c is applied. When the voltage sweep is performed, a current jump occurs at a _softset voltage corresponding to V _softset of FIG. 5 as described with reference to FIG. 5, as shown in FIG. 5 (810). In this case, however, the amount of the jumping current is limited by the compliance current I _c , and thus the magnitude of the jumping current cannot be greater than or equal to the compliance current I _c .

Then, when the voltage is swept in the positive direction again at 0V, it can be seen that a relatively large current flows as shown by reference numeral 830. Accordingly, the transition metal oxide thin film 130 is in a low resistance state, which corresponds to a state in which the resistance is lower than the low resistance state 570 described with reference to FIG. 5. The magnitude of the resistor depends on the magnitude of the compliance current I _c . When the voltage is continuously increased to reach a specific voltage (860), the current does not increase or the increase rate of the current changes. This particular voltage depends on the magnitude of the compliance current I _c . If the voltage is continuously increased to a voltage larger than this specific voltage, an area where the change in current is not large as shown by reference numeral 840 appears.

After the voltage sweep in the positive direction at 0V again, as shown by reference numeral 850, the magnitude of the current decreases, indicating that the transition metal oxide thin film 130 has a high resistance state.

In order to distinguish the anode resistance switching from the anode resistance switching described with reference to FIG. 6, the anode resistance switching described with reference to FIG. 6 is referred to as a first anode resistance switching, and the anode resistance switching described with reference to FIG. 9 is referred to as a second anode resistance switching. When the first anode resistance switching and the second anode resistance switching are used at the same time, the state of the resistor can be changed into three states. In the case of the second anode resistance switching, when the voltage corresponding to the softset appearing in the negative voltage region is applied, the transition metal oxide thin film 130 is changed from the high resistance state 850 to the low resistance state 830. Corresponding to the set of the second positive resistance switching, this voltage is the set voltage V _{BRS II set} of the second positive resistance switching. When the voltage corresponding to the reference numeral 860 of FIG. 9 is applied, the transition metal oxide thin film 130 is changed from the low resistance state 830 to the high resistance state 850 and thus corresponds to the reset of the second anode resistance switching. This voltage may be referred to as a reset voltage V _{BRS II} reset of the second positive resistance switching.

Such switching characteristics are shown in FIGS. 10 and 11. 10 and 11, the transition metal oxide thin film 130 uses a TiO ₂ thin film, and the upper electrode 140 and the lower electrode 120 constitute a resistance change recording element 100 using a Pt electrode. It was. FIG. 10 is a voltage-current diagram showing both the first anode resistance switching characteristic and the second anode resistance switching characteristic, and FIG. 11 is a voltage-current diagram showing the voltage and current of FIG. 10 on a logarithmic scale.

When both the first positive electrode resistance switching and the second positive electrode resistance switching are formed by applying a positive voltage, and then performing a voltage sweep by applying a negative voltage, the first positive electrode resistance switching is not applied when the compliance current I _c is not applied. Same as the characteristics. In the first anode resistance switching, when the current jump occurs on the positive voltage side, the transition metal oxide thin film 130 changes from the high resistance state to the low resistance state. In this case, since the transition metal oxide thin film 130 is changed from a low resistance state to a high resistance state, the first anode resistance switching is reset.

In contrast, the second anode resistance switching is in a high resistance state as described above when the voltage sweep is performed by applying a negative voltage in a state in which a compliance current is applied. When a voltage sweep is performed by applying a positive voltage, a low resistance state is applied when a voltage equal to or greater than a predetermined voltage at which an increase change in current is changed. That is, in this case, when the current jump occurs on the negative voltage side, it is changed from the high resistance state to the low resistance state, so it becomes the set of the second anode resistance switching, and when the increase rate of change of the current on the positive voltage side changes, Since the resistance state is changed, the second positive resistance switching is reset, which is opposite to the first positive resistance switching.

There is almost no difference in resistance between the high resistance state 950 (− ▲ −) of the first positive electrode resistance switching or the high resistance state 960 (− • −−) of the second positive electrode resistance switching. The low resistance state 970 (->-) in the first positive resistance switching is always greater than the low resistance state 980 (-)-in the second positive resistance switching, so that the low value of the first positive resistance switching is low. The resistance state 970 may be referred to as an intermediate resistance state, and the low resistance state 980 in the second anode resistance switching may be referred to as a low resistance state. In this way, three resistance states can be created depending on whether or not a compliance current is applied.

Next, a voltage is applied to the transition metal oxide thin film 130 to change the transition metal oxide thin film 130 into a high resistance state, an intermediate resistance state and a low resistance state (S730). As described above, in the actual driving of the device, it is not appropriate to change the resistance state of the transition metal oxide thin film 130 through voltage sweep, so that the resistance state of the transition metal oxide thin film 130 is changed by applying a pulse voltage. .

First, a case in which the transition metal oxide thin film 130 is changed from the high resistance states 950 and 960 to the intermediate resistance state 970 will be described. In order to change from the high resistance state 950 of the first anode resistance switching to the intermediate resistance state 970, the first anode resistance switching set voltage V _{BRS I set} or more is applied (920). In order to change from the high resistance state 960 of the second anode resistance switching to the intermediate resistance state 970, the first anode resistance is applied after the first anode resistance switching reset voltage V _{BRS I reset} or less is applied 920. More than the switching set voltage V _{BRS I set} is applied (910).

In addition, the case where the transition state of the transition metal oxide thin film 130 is changed from the high resistance states 950 and 960 to the low resistance state 980 will be described. In order to change from the high resistance state 950 of the first anode resistance switching to the low resistance state 980, the second anode resistance switching set voltage V _{BRS II set} or less is applied and the compliance current I _c is applied. (930). Similarly, in order to change from the high resistance state 960 of the second anode resistance switching to the low resistance state 980, -0.6 V or less which is equal to or less than the second anode resistance switching set voltage V _{BRS II set} is applied, and the compliance current ( I _c ) is applied (930).

Next, a case in which the transition state of the transition metal oxide thin film 130 is changed from the intermediate resistance state 970 to the high resistance states 950 and 960 will be described. In order to change from the intermediate resistance state 970 to the high resistance state 950 of the first positive electrode resistance switching, the first positive electrode resistance switching reset voltage V _{BRS Ireset} or less is applied (910). To change from the intermediate resistance state 970 to the high resistance state 960 of the second positive resistance switching, a second positive resistance switching set voltage V _{BRS II set} or less is applied and the compliance current I _c is applied. After operation 930, the second positive electrode resistance switching reset voltage V _{BRS II reset} or more is applied (940).

In order to change the resistance state of the transition metal oxide thin film 130 from the intermediate resistance state 970 to the low resistance state 980, the second anode resistance switching set voltage V _{BRS Ⅱset} or less is applied, and the compliance current is applied. (I _c ) is applied (930).

Next, a case in which the transition metal oxide thin film 130 is changed from the low resistance state 980 to the high resistance states 950 and 960 will be described. To change from the low resistance state 980 to the high resistance state 950 of the first positive electrode resistance switching, the first positive electrode resistance switching reset voltage V _BRSI reset or less is applied (910). In order to change from the low resistance state 980 to the high resistance state 960 of the second positive electrode resistance switching, the second positive electrode resistance switching reset voltage V _{BRS II reset} or more is applied (940).

In order to change the transition metal oxide thin film 130 from the low resistance state 980 to the intermediate resistance state 970, after applying the first anode resistance switching reset voltage V _{BRS I reset} or less (920), The first anode resistance switching set voltage V _{BRS I set} or more is applied (910).

Summarizing the above results, in order to change the transition metal oxide thin film 130 into the high resistance states 950 and 960, the first anode resistance switching reset voltage V _{BRS I reset} is lower than the current resistance state. This may be applied (920). The high resistance states 950 and 960 have a high resistance state 950 of the first positive resistance switching and a high resistance state 960 of the second positive resistance switching, but the resistance magnitudes of the two high resistance states 950 and 960 Since it is almost the same, you may change to any state. However, since it is easy to create the high resistance state 950 of the first anode resistance switching, the first anode resistance switching reset voltage V _{BRS I reset} or less is applied (920). In order to change the transition metal oxide thin film 130 to the intermediate resistance state 970, the first anode resistance switching reset voltage V _{BRS I reset} or less is applied 920 regardless of the current resistance state. At least one anode resistance switching set voltage V _{BRS I set} is applied (910). Also, in order to change the transition metal oxide thin film 130 to the low resistance state 980, the second anode resistance switching set voltage V _{BRS IIset} or less is applied regardless of the current resistance state, and the compliance current I _c is applied. Apply (930).

However, in all of the above cases, a voltage having a range greater than or equal to the set voltage of the single-pole resistance switching, which is a voltage corresponding to V _URSset of FIG. 5, should not be applied. If a voltage having a range greater than or equal to the set voltage (V _URSset ) of the unipolar resistance switching is applied, the unipolar resistance switching characteristic will not be exhibited after that, and therefore, the voltage above this voltage should not be applied. If a voltage having a range greater than or equal to the monopolar resistance switching set voltage (V _URSset ) is applied, the voltage must be formed to exhibit positive polarity resistance switching characteristics by applying the monopolar resistance switching reset voltage corresponding to V _URSreset of FIG. 1 again. .

8, according to the resistance state of the transition metal oxide thin film 130, the information is recorded by assigning the high resistance state to "0", the middle resistance state to "1", and the low resistance state to "2" ( S740).

In the above description, a case in which the positive voltage is applied to form the positive resistance switching and the negative voltage is applied to the positive resistance switching characteristics are described, but the present invention is not limited thereto. Only the polarity is reversed, but the rest of the process is the same.

Although the preferred embodiments of the present invention have been shown and described above, the present invention is not limited to the specific preferred embodiments described above, and the present invention belongs to the present invention without departing from the gist of the present invention as claimed in the claims. Various modifications can be made by those skilled in the art, and such changes are within the scope of the claims.

According to the information recording method of the resistance change recording device according to the present invention, it is possible to reduce the power consumption by lowering the driving voltage of the resistance change recording device by using the anode resistance switching characteristics, and to improve the speed of the device by shortening the resistance switching time. It becomes possible. In addition, the data retention function characteristics and the ability to switch a lot can be improved. In addition, a magnetic change recording device having a plurality of states as well as two states of “0” and “1” may be implemented by applying a compliance current.

Claims (8)

An information recording method of a resistance change recording element comprising a structure of a lower electrode, a transition metal oxide thin film formed on the lower electrode, and an upper electrode formed on the transition metal oxide thin film, Applying a voltage to the transition metal oxide thin film to form a bipolar resistance switching (BRS) characteristic of the transition metal oxide thin film to exhibit bipolar resistance switching (BRS) characteristics; Less than the set voltage of unipolar resistance switching (URS) of the transition metal oxide thin film and the magnitude of the soft set voltage without applying a current to the formed transition metal oxide thin film Varying the resistance of the transition metal oxide thin film by applying a voltage having a greater mutually opposite polarity, respectively; And And assigning "0" or "1" according to the resistance size of the transition metal oxide thin film. The softset voltage is a voltage at which the magnitude of current discontinuously increases at a voltage smaller than the set voltage of single-pole resistance switching when voltage sweep is applied to the transition metal oxide thin film. An information recording method of a resistance change recording element. An information recording method of a resistance change recording element comprising a structure of a lower electrode, a transition metal oxide thin film formed on the lower electrode, and an upper electrode formed on the transition metal oxide thin film, Applying a voltage to the transition metal oxide thin film to form the transition metal oxide thin film to exhibit an anode resistance switching characteristic; Applying a voltage to the formed transition metal oxide thin film that is greater than the reset voltage of the first anode resistance switching and less than the set voltage of the unipolar resistance switching, or After applying a voltage that is greater than the magnitude of the reset voltage of the first positive resistance switching and less than the magnitude of the set voltage of the monopolar resistance switching, is greater than the magnitude of the set voltage of the first positive resistance switching and less than the magnitude of the set voltage of the monopolar resistance switching. Apply voltage, Varying the resistance of the transition metal oxide thin film by applying a compliance current that is greater than the set voltage of the second anode resistance switching and less than the set voltage of the unipolar resistance switching and limits the increase in current magnitude. ; And And assigning "0", "1", or "2" according to the resistance of the transition metal oxide thin film. The first anode resistance switching is a cathode resistance switching in a state in which no additional current is applied, and the second anode resistance switching is a cathode resistance switching in a state in which a compliance current for limiting an increase in current is applied. Information recording method of resistance change recording element. The method according to claim 1 or 2, The anode resistance switching forming step, Unipolar resistance switching forming so that the unipolar resistance switching characteristic appears on the transition metal oxide thin film; And And applying a voltage greater than the magnitude of the unipolar resistance switching reset voltage and less than the set voltage of the unipolar resistance switching to the transition metal oxide thin film formed to exhibit the unipolar resistance switching characteristic. How to record information. The method according to claim 1 or 2, And the voltage applied to the step of changing the resistance is a voltage in the form of a pulse. Forming a lower electrode; Forming a transition metal oxide thin film on the lower electrode; Forming an upper electrode on the transition metal oxide thin film; Unipolar resistance switching forming so that the unipolar resistance switching characteristic appears on the transition metal oxide thin film; And Applying a voltage to the transition metal oxide thin film formed so that the unipolar resistance switching characteristic is greater than the reset voltage of the unipolar resistance switching and smaller than the set voltage of the unipolar resistance switching. Method of manufacturing recording element. A resistance change recording device manufactured by the method of claim 5. The method of claim 6, The transition metal oxide thin film is a resistance change, characterized in that the single layer (multi-layer) or a multi-layer consisting of one or more selected from TiO ₂ , NiO, HfO ₂ , Al ₂ O ₃ , ZrO ₂ and ZnO. Recording element. The method of claim 6, And at least one of the lower electrode and the lower electrode is at least one of Pt, Ru, Ir, Ag, Al, and TiN.

Images