CN210120153U - Small-area electrode resistive random access memory with filament mechanism - Google Patents
Small-area electrode resistive random access memory with filament mechanism Download PDFInfo
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- CN210120153U CN210120153U CN201920522337.7U CN201920522337U CN210120153U CN 210120153 U CN210120153 U CN 210120153U CN 201920522337 U CN201920522337 U CN 201920522337U CN 210120153 U CN210120153 U CN 210120153U
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Abstract
The utility model provides a small area electrode resistance random access memory of filament mechanism, resistance random access memory's structure from the top down is a plurality of upper electrodes in proper order, insulating medium film, resistance layer film, bottom electrode layer, substrate layer, and wherein the bottom electrode layer is ohmic contact with resistance layer, insulating medium film's thermal breakdown voltage ET1Film smaller than resistance change layer ET2. The contact area of the upper electrode and the resistive material is reduced by forming the effective area of the conductive path, so that the reduction of the operating current/voltage is realized. And the structure has no requirement on whether the selection of the electrode material can be directly contacted with the resistance change layer to form ohmic contact, and can realize the control of the generation position of an electrode access.
Description
Technical Field
The utility model belongs to semiconductor resistive random access memory field in the super large integrated scale, concretely relates to small area electrode resistive random access memory of filament mechanism.
Background
The resistive random access memory is a novel memory device which changes the resistance value of a resistive material by adding voltages with different polarities and magnitudes so as to store data. The structure mainly comprises an upper electrode, a resistance change material and a lower electrode. Based on the position of the resistive random access memory, the resistive random access memory is mainly divided into two types, one type is an interface effect resistive random access memory, the resistive random access memory is generated at the non-ohmic contact layer interface of a metal/semiconductor or a semiconductor/semiconductor, the other type is a body effect resistive random access memory, the upper electrode and the lower electrode of the body effect resistive random access memory are in ohmic contact with a resistive random access material layer directly, and the resistive random access memory is generated in the resistive random access material layer. The resistance change mechanism of the body-effect resistance change memory is generally a conductive filament mechanism. For the resistive random access memory of a body effect filament mechanism, higher operation current, especially voltage/current from low resistance to high resistance (Reset operation), seriously restricts the application prospect. However, reducing the actual electrode area is one of effective means for reducing the operating current of the filament-mechanism resistive random access memory. The smaller the electrode area is, the smaller the effective area of the electric field loaded on the resistive random access memory is, the more concentrated the positions where the conductive filaments are formed, the less the operating voltage/current is, and meanwhile, the more concentrated the performance parameters of the resistive random access memory, and the fluctuation is reduced. The bottleneck encountered in the prior art is that it is difficult to make the electrode smaller, especially to reach the hundreds nanometer and ten nanometer level, and the cost is very high and the electrode is unstable.
The following three methods are mainly used for forming the effective small-area electrode resistive random access memory in the prior art.
One is the physical shape of the control electrode, and background art 1(CN102891253A) discloses that the upper electrode is embedded within the resistive switching material, with the width of the top of the upper electrode being greater than the width of the bottom thereof. Background art 2(CN104409627A) discloses that a resistance change thin film is confined in a groove of an isolation layer, so that the resistance change thin film naturally forms a V-shape, the size and thickness of an actual device are greatly reduced, and a peak-like structure is naturally formed on the resistance change thin film by a top electrode.
One is to guide the formation of electrode filaments, and background art 3(CN102664235A) discloses a resistance change memory including an Al electrode layer, SiO electrode layer2A layer, a Si layer, a resistance change layer and a lower electrode layer; wherein the Al electrode layer is electrically connected with the resistance change layer through one or more conductive channels, and the conductive channels are formed by Al passing through SiO2The layer defects penetrate into the Si layer to dissolve Si in Al. Background art 4(CN103515534A) discloses the use of a patterned region of a silicon substrate as a bottom electrode and a selective electrodeThe selective heavy doping combined method enables the electric field to be controllably concentrated in the peak range of the local area by selecting the proper ion implantation direction. Background art 5(CN103594622A) discloses a triangular region in a resistive material thin film, in which the doping concentration of metal ions is higher than that of the surrounding region, so that the resistive behavior of the device can be controlled to occur at a sharp peak. Background art 6(CN102738386A) discloses a method of enhancing the local electric field strength in a storage medium by providing a local control electrode on a lower electrode, making conductive filaments easier to form along the control electrode.
Still another is to utilize the interfacial barrier effect, and background art 7(CN107204397A) discloses a first metal oxide layer doped with metal atoms as a resistance change layer; a second metal oxide layer is formed over the first metal oxide layer as a tunneling layer. Background art 8(CN102593351A) discloses a double-layer resistive layer, in which an electron current blocking layer is provided on an upper-layer resistive layer, an upper electrode is provided on the electron current blocking layer, and the energy band difference between the upper electrode and the conduction band of the electron current blocking layer is less than 1 eV. The type of conductive filament is controlled by controlling the dielectric constant and the band width and affinity.
In contrast to the three methods described above, the guided formation of electrode filaments is of great utility since it does not involve fine etching, nor the matching of work function, energy band width and affinity between materials.
However, the method of guiding the electrode filament to reduce the effective electrode area in the prior art still has the following limitations, such as the limitation of selecting the electrode material in the background art 3, which not only requires that the electrode material forming the electrode filament naturally form ohmic contact when contacting with the resistive layer, but also requires that Al is SiO-doped2The penetration of layer defects into the Si layer causes Si to dissolve in the Al forming electrode filaments, and the uncontrollable location of filament formation. In addition to the limitation that ohmic contact is naturally formed when an electrode material for forming an electrode filament is in contact with a resistance change layer, the background technologies 3-4 also change the bulk phase structure of the resistance change material, so that the uncertainty of resistance change behavior is enhanced, and when the structure for forming the conductive filament is guided to be damaged, the whole device is scrapped and cannot be used for multiple times.
Disclosure of Invention
To the technical problem that exists among the above-mentioned prior art, the utility model aims to provide a resistive random access memory of small area electrode of filament mechanism through reducing the area of contact of top electrode and resistance change material to realize the reduction of operating current/voltage. And the structure has no requirement on whether the selection of the electrode material can directly form ohmic contact with the resistance change layer, the electrode structure can be repeatedly used for many times, and the electrode structure can realize the nano-scale accurate control of the position of the electrode.
The utility model discloses a structure is as shown in FIG. 1, and resistive random access memory's structure from the top down is a plurality of upper electrode in proper order, insulating medium film that the thermal conductivity is low, resistive layer film, bottom electrode layer. Wherein the lower electrode layer is in ohmic contact with the resistance change layer, and the thermal breakdown voltage E of the insulating dielectric filmT1Film ET smaller than resistance change layer2. The probe is contacted with the upper electrode, the area of the tip of the probe is smaller than that of the electrode, and a certain DC voltage E is appliedT0In which ET1≤ET0＜ET2The voltage ET0The insulating layer is thermally broken down, and a conductive path is formed between the upper electrode and the resistance change layer, wherein the cross section of the conductive path is the effective area of the upper electrode. The area of the tip is sub-micron or micron, but the area of the channel created by thermal breakdown is generally smaller than the area of the tip. Research shows that the cross-sectional area of the conductive path is proportional to the radius of the conductive filament, which is generally only a few nanometers, so that the effective area of the electrode is also on the nanometer scale.
The design principle of the structure is shown in FIG. 2, when the DC voltage applied to the upper electrode satisfies ET1ET0＜ET2When the resistance change layer thin film is damaged, the insulating medium thin film is thermally broken down, the electrode passage is formed between the upper electrode and the resistance change layer thin film, and the electrode passage formed by thermal breakdown is pricked on the resistance change layer thin film just like a nanometer sharp needle which pricks through the insulating medium thin film, so that a small electrode of the resistance change memory is realized, the actual electrode area is reduced, the current power consumption is reduced, and the performance is optimized.
Electric field intensity of thermal breakdown of insulating dielectric filmWherein A, a and b are constants, d is the dielectric film thickness, σ0Is the initial conductivity; lambda is the thermal conductivity of the dielectric film, the larger lambda is, the larger breakdown field intensity is, the thicker the dielectric film is, the more defects are, and the breakdown field intensity is reduced. The thermal breakdown voltage E of the insulating dielectric film is controlled by controlling the thickness, the thermal conductivity and the internal defects of the insulating dielectric filmT1Film smaller than resistance change layer ET2。
The technical scheme of the utility model is that:
a small-area electrode of a filament mechanism resistance random access memory is characterized by sequentially comprising an upper electrode, an insulating dielectric film, a resistance change layer film and a lower electrode from top to bottom, wherein the lower electrode is in ohmic contact with the resistance change layer, and the thermal breakdown voltage E of the insulating dielectric filmT1Film smaller than resistance change layer ET2Applying a DC voltage E by using a probe having a tip area smaller than that of the upper electrodeT0In which ET1≤ET0＜ET2And thermally breaking down the insulating dielectric film to form a conductive path between the upper electrode and the resistance change layer film, wherein the cross section area of the conductive path is the effective area of the upper electrode.
A preparation method of a small-area electrode filament mechanism resistance random access memory comprises the following steps:
1) sequentially preparing an ohmic contact lower electrode and a resistance change film on the substrate layer;
2) preparing an insulating dielectric film on the resistance change film layer, wherein the thermal breakdown voltage E of the insulating dielectric filmT1Film smaller than resistance change layer ET2；
3) Preparing a plurality of upper electrodes on the insulating medium film;
4) applying a DC voltage E by using a probe having a tip area smaller than an upper electrode areaT0In which ET1≤ET0＜ET2Thermally breaking down the insulating dielectric film to form one or more conductive paths between the upper electrode and the resistance change layer film, wherein the cross-sectional area of one conductive path or the total cross-sectional area of the plurality of conductive paths is the power-onThe effective area of the pole.
The insulating dielectric film is equivalent to a plurality of open switches respectively arranged between a plurality of upper electrodes and the resistance change layer film, is equivalent to a plurality of resistance change memories connected in parallel, and is equivalent to the switch between the upper electrode and the resistance change layer film being closed when thermal breakdown occurs at the position of the insulating dielectric film below one upper electrode. When the resistance variable memory is worn out due to fatigue, other memories can be selected by replacing the electrodes, and the multiplexing of the memory is realized.
Further, the insulating dielectric film is an organic resin film having low thermal conductivity, preferably a BCB (benzocyclobutene) film.
Further, the material of the resistance change layer film is a single layer or a plurality of layers; the lower electrode layer is Pt.
Further, the insulating medium film is private Si prepared by radio frequency sputtering3N4Or Al2O3The thickness of the film is 5-10 nm.
Furthermore, the insulating medium film is TiO prepared by anodic oxidation2The thickness of the film is 5-10 nm.
Compared with the prior art, the utility model discloses an actively the effect does:
the memory can obtain a very small actual electrode by using the conventional technical process cost, reduces the cost, optimizes the device, greatly reduces the operating current, and simultaneously enables the performance parameters of the resistive random access memory to be more concentrated and reduces the fluctuation. The area of the needle tip is submicron or micron, but the area of a channel generated by thermal breakdown is generally smaller than that of the needle tip, and the design can realize smaller actual electrode area with lower cost, thereby achieving the effect of nanometer level. In addition, the electrode structure has no requirement on whether the selection of the electrode material can be directly contacted with the resistance change layer to form ohmic contact, the electrode structure can be repeatedly used for many times, and the position of a conductive path of the electrode structure is generated below the probe, so that the control of the position of the electrode path is realized.
Drawings
Fig. 1 is a structural diagram of a resistive random access memory of the present invention;
FIG. 2 is a schematic diagram of the structure of the present invention;
Detailed Description
The present invention will be described in further detail by way of example, but this is not a limitation of the present invention, and various modifications and improvements can be made according to the basic idea of the present invention, but all within the scope of the present invention as long as they do not depart from the basic idea of the present invention.
[ example 1]
Selecting a copper sheet as a lower electrode, and depositing a boron nitride film on the copper sheet as a resistance change layer by a magnetron sputtering method, wherein the thickness of the boron nitride film is about 50 nm; a plurality of aluminum metal top electrodes of about 150nm thickness were deposited by PVD process using a shadow mask. The electrical characteristics are tested by a semiconductor parameter analyzer, the device is a unipolar resistive random access memory device, unipolar operation can be realized, the Reset voltage is distributed in a concentrated mode at about 1.3V, the distribution interval is plus or minus 0.3V, namely the Reset voltage is distributed at about 1-1.6V, and the Reset voltage is distributed in a concentrated mode at about 1.3V.
Under the same preparation process conditions, an alumina insulating layer with the thickness of 5nm is prepared between an upper electrode and a resistance change layer by using a thermal oxidation process, the device is a unipolar resistance change memory device, unipolar operation can be realized, the Reset voltage is intensively distributed at about 0.7V, the distribution interval is plus or minus 0.2V, namely the Reset voltage is distributed at about 0.9-0.5V, wherein the Reset voltage is distributed at about 0.7V.
[ example 2]
Selecting Pt substrate as lower electrode, and growing N-type TiO with thickness of about 70nm on the Pt substrate by ion beam assisted reactive sputtering2Film on TiO2Preparing a P-type NiO film with the thickness of about 70nm on the film by ion beam assisted reactive sputtering, and preparing the NiO film by TiO2the/NiO laminated structure is used as a resistance change layer; by ion sputtering process, through a mask, on TiO2Au electrodes with the thickness of 30nm are prepared on the/NiO laminated structure. The electrical characteristics are tested by a semiconductor parameter analyzer, the device is a unipolar resistive random access memory device, unipolar operation can be realized, the Reset voltage is intensively distributed at about 1.5V, the distribution interval is plus or minus 0.5V, namely the Reset voltage is distributed at 1-2V, wherein the Reset voltage is intensively distributed atAbout 1.5V.
Under the same preparation process conditions, a BCB (benzocyclobutene) film is prepared between an upper electrode and a resistance change layer by using a spin coating process, the thickness of the BCB film is 10nm, the device is a unipolar resistance change memory device, unipolar operation can be realized, the Reset voltage of the device is intensively distributed at about 0.5, the distribution interval is plus or minus 0.2V, namely the Reset voltage is distributed at about 0.3-0.7V, and the Reset voltage is distributed at about 0.5V.
Claims (6)
1. The small-area electrode resistive random access memory with a filament mechanism is characterized in that the resistive random access memory is sequentially provided with a plurality of upper electrodes, an insulating dielectric film, a resistive layer film, a lower electrode layer and a substrate layer from top to bottom, wherein the lower electrode layer is in ohmic contact with the resistive layer, and the thermal breakdown voltage E of the insulating dielectric filmT1Film smaller than resistance change layer ET2。
2. The small-area resistance change memory of a filament mechanism according to claim 1, wherein the upper electrode is contacted by a probe having a tip area smaller than an electrode area, and a direct current voltage E is appliedT0In which ET1≤ET0＜ET2The voltage ET0The insulating layer is thermally broken down to form a conductive path between the upper electrode and the resistive layer, and the cross-sectional area of the conductive path is the effective area of the upper electrode.
3. The filament-machined small-area electrode resistance change memory according to claim 2, wherein the insulating dielectric film is an organic resin film having low thermal conductivity and is a benzocyclobutene film.
4. The filament-machined small-area resistive random access memory of claim 2, wherein the insulating dielectric film is rf sputter fabricated Si3N4Or Al2O3The thickness of the film is 5-10 nm.
5. Small area resistive switching memory of the filament mechanism as claimed in claim 2The device is characterized in that the insulating medium film is TiO prepared by anodic oxidation2The thickness of the film is 5-10 nm.
6. The filament-machined small area resistive random access memory of claim 2, wherein the material of the resistive layer film is a single layer or a plurality of layers.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN109980083A (en) * | 2019-04-17 | 2019-07-05 | 河南大学 | A kind of small area electrode resistance-variable storing device of filament mechanism and preparation method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN109980083A (en) * | 2019-04-17 | 2019-07-05 | 河南大学 | A kind of small area electrode resistance-variable storing device of filament mechanism and preparation method thereof |
| CN109980083B (en) * | 2019-04-17 | 2024-06-07 | 河南大学 | Small-area electrode resistance random access memory with filament mechanism and preparation method thereof |
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