Based on resistance-variable storing device of vanadium oxide/Zinc oxide laminate structure and preparation method thereof
Technical field
The invention belongs to microelectronics technology, be specifically related to a kind of resistance-variable storing device based on vanadium oxide/Zinc oxide laminate structure and preparation method thereof.
Technical background
Resistance-variable storing device is owing to having higher integration density, faster erasable speed, long retention time, and the potential of multilevel storage is arranged, and has been subject to researcher's extensive concern recent years.The design of resistive research on mechanism, new structure, the proposition of new material, the researcher is pursuing higher integration density, the faster breakthrough of read or write speed, multilevel storage.
The structure of resistance-variable storing device is simple metal-insulator-metal (MIM) structure, i.e. the sandwich structure of upper/lower electrode and middle change resistance layer, and most of change resistance layers are single layer structure.In recent years, because double-deck advantage, the researcher began to have proposed some lamination resistive structures, and performance of devices is improved.(Reliable resistiveswitching device based on bi-layers of ZrO in the document of Gwangju, Korea Science and Technology research institute in 2009
x/ HfO
xFilms), the people such as J.Lee adopts ZrO
x/ HfO
xLaminated construction, obtained stable bipolarity resistive characteristic, and this device has the characteristic potential of multilevel storage.U.S.'s University of Toledo document (Switching Characteristicsof Ru/HfO in 2012
2/ TiO
2-x/ Ru RRAM Devices for Digital and Analog NonvolatileMemory Applications) in, the people such as B.Long and Y.Li pass through HfO
2/ TiO
2-xLaminated construction has obtained higher conforming bipolar structure.
Novel laminated structure can overcome the deficiency that exists in the single layer structure, in conjunction with the advantage of single layer structure, improve the performance of single layer structure, the exploration of novel laminated structure and research become researcher's a focus.
In a kind of resistance-variable storing device based on vanadium oxide film and preparation method thereof (CN102130295A), this seminar uses vanadium oxide as the dielectric layer of resistance-variable storing device, obtained a kind of resistance-variable storing device of single-stage, the reset electric current is 40mA, the vanadium oxide film of individual layer has larger reset electric current during as the change resistance layer material; In a kind of controlled resistance-variable storing device of polarity of zinc oxide and preparation method thereof (CN102194995A), this seminar can obtain single-stage, bipolarity, non-polar resistance-variable storing device by depositing different upper/lower electrodes, the reset electric current is 10mA, but consistency and repeatability still need to improve.
Summary of the invention
The objective of the invention is the technical problem for above-mentioned existence, a kind of resistance-variable storing device based on vanadium oxide/Zinc oxide laminate structure and preparation method thereof is provided, this resistance-variable storing device has zinc oxide bipolarity and the controlled advantage of unipolarity polarity, can improve consistency and the repeatability of device.
Technical scheme of the present invention:
A kind of resistance-variable storing device based on vanadium oxide/Zinc oxide laminate structure is made of bottom electrode, change resistance layer and top electrode, and change resistance layer is the laminated construction that is comprised of vanadium oxide dielectric layer and zinc oxide dielectric layer, and the composition of zinc oxide is ZnO
1-x, 0<x<0.5 wherein, the thickness of zinc oxide dielectric layer is 1-500nm; The composition of vanadium oxide is VO
y, 0.5<y<2.5 wherein, the thickness of vanadium oxide dielectric layer is 1-500nm.
Described upper/lower electrode material is conducting metal, metal alloy and conductive metallic compound, and wherein conducting metal is Ta, Cu, Ag, W, Ni, Al or Pt; Metal alloy is Pt/Ti, Ti/Ta, Cu/Ti, Cu/Au, Cu/Al or Al/Zr; Conductive metallic compound is TiN or ITO.
A kind of preparation method of described resistance-variable storing device based on vanadium oxide/Zinc oxide laminate structure, step is as follows, and wherein vanadium oxide dielectric layer and zinc oxide dielectric layer thin film technology do not limit precedence:
1) take the Si sheet as substrate, utilize the method for thermal oxidation to prepare SiO
2Insulating barrier;
2) at SiO
2Utilize the method for ion beam sputtering to prepare the Ti adhesion layer on the insulating barrier;
3) prepare bottom electrode at the Ti adhesion layer;
4) adopt direct current sputtering or radio frequency sputtering method deposition vanadium oxide film at bottom electrode, the sputtering technology condition is: base vacuum is less than 10
-4Pa, underlayer temperature are that room temperature-200 ℃, operating pressure 0.1-2Pa, partial pressure of oxygen are that 5%-30%, sputtering power are 50-250W;
5) adopt direct current sputtering or radio frequency sputtering method depositing zinc oxide film at vanadium oxide film, the sputtering technology condition is: base vacuum is less than 10
-4Pa, underlayer temperature are that room temperature-300 ℃, operating pressure are that 0.1-2Pa, partial pressure of oxygen are that 5%-40%, sputtering power are 50-250W;
6) prepare top electrode at zinc-oxide film;
7) utilize method growth one deck SiO of PECVD at top electrode
2As protective layer.
The described method for preparing upper/lower electrode is ion beam sputtering, magnetron sputtering or electron beam evaporation process.
Technical Analysis of the present invention:
The difference of this resistance-variable storing device and traditional single layer structure is, there are two-layer dielectric layer vanadium oxide, zinc oxide, under the effect of extra electric field, the generation rate in a kind of material oxygen room is greater than another material, in a kind of material, just preferentially form like this conductive channel in oxygen room, then the electric field of another material just reaches the requirement that produces the oxygen room, forms the passage in oxygen room.Just the opposite in the Reset process, preferentially form the rear fracture of oxygen space channels.This vanadium oxide/Zinc oxide laminate structure owing to the process at reset is a progressive process, can obtain by the reset voltage of various amplitude the resistance of different high-impedance states.
Advantage of the present invention and beneficial effect are:
This resistance-variable storing device adopts vanadium oxide/Zinc oxide laminate structure, has zinc oxide bipolarity and the controlled advantage of unipolarity polarity, has improved consistency and the repeatability of device; Compare with mono-layer oxidized vanadium, the reset electric current has dropped to below the 10mA; In the bipolarity test process, have a progressive reset process, can obtain by the reset voltage of various amplitude the resistance of different high-impedance states, can obtain at least 3 resistance values, and the resistance value ratio more than 10 times is arranged between each resistance value.
Description of drawings
Fig. 1 is this resistance variation memory structure schematic diagram.
Among the figure: 1. bottom electrode 2. vanadium oxide dielectric layers 3. zinc oxide dielectric layers 4. top electrodes
Fig. 2 is this resistance-variable storing device unipolarity electrology characteristic curve.
Fig. 3 is that this resistance-variable storing device uses analyzing parameters of semiconductor instrument DC scanning, the ambipolar curve of set process and progressive reset process.
Fig. 4 be this resistance-variable storing device when bipolarity, the reset process adopt amplitude be-0.5V and-the endurance curve of three attitudes of 0.85V acquisition, resistance ratio is greater than 10 times between each attitude.
Embodiment
Embodiment 1:
A kind of resistance-variable storing device based on vanadium oxide/Zinc oxide laminate structure as shown in Figure 1, is made of bottom electrode 1, change resistance layer and top electrode 4, and change resistance layer is the laminated construction that is comprised of vanadium oxide dielectric layer 2 and zinc oxide dielectric layer 3, and the composition of zinc oxide is ZnO
1-x, wherein x is 0.1, the thickness of zinc oxide dielectric layer is 30nm; The composition of vanadium oxide is VO
y, wherein y is 0.15, the thickness of vanadium oxide dielectric layer is 30nm; Bottom electrode is that Pt, thickness are 50nm, and powering on very, W, thickness are 50nm.
The preparation method of this resistance-variable storing device, step is as follows:
1) take the Si sheet as substrate, use the oxide-diffused stove, the method by thermal oxidation prepares SiO at silicon substrate
2Insulating barrier;
2) at SiO
2Utilize the method for ion beam sputtering to prepare the thick Ti adhesion layer of one deck 10nm on the insulating barrier;
3) adopt the method for electron beam evaporation at the thick Pt bottom electrode of Ti adhesion layer deposition 50nm;
4) adopting the radio frequency sputtering method deposit thickness at bottom electrode is the 30nm vanadium oxide film, and the sputtering technology condition is: target is φ 60mm vanadium oxide ceramic target, and the target intercept is 6.5cm, and base vacuum is less than 10
-4Pa, underlayer temperature are that 200 ℃, operating pressure 1.0Pa, partial pressure of oxygen are 20%, sputtering power is 100W;
5) adopting the radio frequency sputtering method deposit thickness at vanadium oxide film is the 30nm zinc-oxide film, and the sputtering technology condition is: target is φ 60mm zinc oxide ceramic target, and the target intercept is 6.5cm, and base vacuum is less than 10
-4The Pa underlayer temperature is that 200 ℃, operating pressure are that 0.5Pa, partial pressure of oxygen are 20%, sputtering power is 50W;
6) be 50nm tungsten top electrode by Deposited By Dc Magnetron Sputtering thickness on zinc-oxide film, the process conditions of magnetically controlled DC sputtering are: target is φ 60mm metal tungsten target, and the target intercept is 6.5cm, operating pressure 0.5Pa, and Ar flow 20sccm, sputtering power are 50W;
7) utilize method growth one deck SiO of PECVD at top electrode
2As protective layer.
Electrology characteristic is tested by analyzing parameters of semiconductor, and this device is a kind of non-polar device, can realize the bipolarity operation, as shown in Figure 2; Also can realize the unipolarity operation, as shown in Figure 3; By adjusting the amplitude of reset voltage, when reset voltage was 0.5, high-impedance state was about 600ohm, and when the amplitude of reset voltage was 0.85, high-impedance state was about 60kohm, as shown in Figure 4.
Embodiment 2:
A kind of resistance-variable storing device based on vanadium oxide/Zinc oxide laminate structure, structure is substantially the same manner as Example 1, and difference is take W as bottom electrode, thickness is 50nm, and TiN is that top electrode, thickness are 100nm.
The preparation method of this resistance-variable storing device, step is as follows:
1), 2) identical with embodiment 1;
3) be 50nm tungsten bottom electrode by Deposited By Dc Magnetron Sputtering thickness on the Ti adhesion layer, the technological parameter of magnetically controlled DC sputtering: target is φ 60mm metal tungsten target, and the target intercept is 6.5cm, and operating pressure is 0.5Pa, and the Ar flow is 20sccm, and sputtering power is 50W;
4) adopting the radio frequency sputtering method deposit thickness at bottom electrode is the 30nm vanadium oxide film, and the sputtering technology condition is: target is φ 60mm vanadium oxide ceramic target, and the target intercept is 6.5cm, and base vacuum is less than 10
-4Pa, underlayer temperature are that 200 ℃, operating pressure 1.0Pa, partial pressure of oxygen are 20%, sputtering power is 100W;
5) adopting the radio frequency sputtering method deposit thickness at vanadium oxide film is the 30nm zinc-oxide film, and the sputtering technology condition is: target is φ 60mm zinc oxide ceramic target, and the target intercept is 6.5cm, and base vacuum is less than 10
-4The Pa underlayer temperature is that 200 ℃, operating pressure are that 1.0Pa, partial pressure of oxygen are 40%, sputtering power is 100W;
6) on zinc-oxide film, be the 100nmTiN top electrode by Deposited By Dc Magnetron Sputtering thickness, the technological parameter of magnetically controlled DC sputtering: target is φ 60mm metal titanium targets, and the target intercept is 6.5cm, and operating pressure is 0.5Pa, nitrogen partial pressure is 7%, and sputtering power is 100W;
7) utilize method growth one deck SiO of PECVD at top electrode
2As protective layer.
Electrology characteristic is by the test of analyzing parameters of semiconductor instrument, and device shows as the bipolarity characteristic, and device has preferably consistency.
Embodiment 3:
A kind of resistance-variable storing device based on vanadium oxide/Zinc oxide laminate structure, structure is substantially the same manner as Example 1, and difference is that take W as bottom electrode, W is top electrode, and thickness is 50nm.
The preparation method of this resistance-variable storing device, the preparation technology of step and W electrode is identical with embodiment 1.
Embodiment 4:
A kind of resistance-variable storing device based on vanadium oxide/Zinc oxide laminate structure, structure is substantially the same manner as Example 1, and difference is that take Pt as bottom electrode, Cu is top electrode, and thickness is 50nm.
The preparation method of this resistance-variable storing device, the preparation technology of step and Pt electrode is identical with embodiment 1.
Top electrode Cu is by the method preparation of magnetically controlled DC sputtering, and the concrete technology condition is: target is φ 60mm metallic copper target, and the target intercept is 6.5cm, and operating pressure is 1Pa, and the Ar flow is 20sccm, and sputtering power is 50W.
The testing result summary sheet of embodiment 1-4: