CN103441214B - A kind of preparation method of resistance-variable storing device - Google Patents
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Abstract
The invention discloses a kind of preparation method of resistance-variable storing device, described resistance-variable storing device comprises hearth electrode, resistive dielectric layer material and the top electrode assembled successively, the preparation of described resistive dielectric layer material comprises the following steps: pass in reactor by the first presoma, the first inert gas, the second presoma, the second inert gas first in order, through a circulation of pyrogen sublayer deposition, hearth electrode deposits one deck single metal oxide film; Then plasma enhanced process is carried out to film; Last cycle alternation carries out above-mentioned steps.The present invention introduces a kind of brand-new in-situ plasma and strengthens hot atom layer deposition techniques in the preparation process of resistive dielectric layer, can regulate surface topography and the defect of metal-oxide film on a large scale; The resistance-variable storing device prepared, can realize the accurate control to device resistance switching characteristic, reach to devices switch ratio, erasable voltage adjustable, and there is splendid resistive stability.
Description
Technical field
The present invention relates to semiconductor applications, particularly relate to a kind of preparation method of resistance-variable storing device.
Background technology
Along with the arriving of integrated circuit technology 32nm technology node, traditional flash storage encounters a series of problem, wherein, topmost problem is, along with tunnel oxide layer thickness is more and more less, the earial drainage of electric charge becomes more and more serious, directly affects the data retention energy of flash storage.In recent years, various novel nonvolatile memory is developed rapidly, as ferroelectric memory, magnetic memory, phase transition storage and resistance-variable storing device (RRAM), RRAM rely on its structure simple, low in energy consumption, can fast reading and writing and can the advantages such as high-density city be realized, become " general " type nonvolatile memory of most competitiveness of future generation.
RRAM utilizes change resistance layer material under voltage effect, has the resistance switch characteristic of resistance states reversible transition, realizes the storage of information.The structure of RRAM comprises substrate, hearth electrode, top electrode and is positioned at the resistive dielectric layer between hearth electrode and top electrode, and wherein, resistive dielectric layer is the core of RRAM, and thickness only has tens nanometers usually.The micromechanism that RRAM realizes electric resistance changing is generation and the fracture of conductive nano silk in resistive dielectric layer.Because conductive nano silk only has a few nanometer usually, the requirement of memory device miniaturization can be met; In addition, resistive dielectric layer is generally simple metal oxide, and preparation technology and microelectronic technique are completely compatible.
The preparation technology of RRAM is simple, wherein it is crucial that the preparation of resistive dielectric layer.At present, the technology of preparing of resistive dielectric layer mainly contains sputtering, chemical vapour deposition (CVD), pulsed laser deposition, electron beam evaporation, ald (ALD) and Sol A MP.AMp.Amp gel etc.Realize the ALD technology of thin film deposition based on ALT pulse endless form, accurately can control film thickness, obtain densification, evenly, there is the large area film of high conformality.Along with the development of nanometer technology and semiconductor integrated circuit technique are to the requirement of device miniaturization, as a kind of emerging ultrathin film technology of preparing, ALD technology rely on its extensive three-dimensional integrated in the advantage of uniqueness, become the important preparation means of one of resistance-variable storing device.
In ALD technology, the growth of film is carried out in a kind of mode of circulation, and a circulation comprises four-stage: (1) the first presoma enters reaction chamber in the mode of gas pulses, and is chemisorbed on substrate surface; (2) after adsorption is saturated, with inert gas by unnecessary presoma blowout reaction chamber; (3) the second presoma enters reaction chamber in the mode of gas pulses, and reacts with the first presoma that the last time is adsorbed on surface; (4) question response completely after, then with inert gas by unnecessary the second presoma and accessory substance blowout reaction chamber thereof.Cycling deposition one deck ultra-thin materials, deposition rate obtains film thickness for often circulating and is about
repetitive cycling is until required film thickness.
The technique for atomic layer deposition preparing resistance-variable storing device in existing research is mainly hot atom layer deposition techniques and plasma enhanced atomic layer deposition (PEALD) technology, the preparation process of two kinds of technology is all deposited as basis with the periodic cycle of ALD: hot atom layer deposition techniques reacts using steam as the second presoma and the first presoma, such as, the people such as J.Zhang (Structural, optical, electrical and resistive switching properties of ZnO thin filmsdeposited by thermal and plasma-enhanced atomic layer deposition, Appl.Surf.Sci.282, 395(2013)) hot atom layer deposition techniques is used to prepare zinc-oxide film, this film demonstrates good conductivity, resistivity can reach 10
-3Ω .cm magnitude, but zinc-oxide film prepared by the method does not possess resistance switch characteristic, plasma enhanced atomic layer deposition technology reacts using plasma as the second presoma and the first presoma, such as, the people such as J.Zhang (Bipolar resistive switching characteristics of low temperature grown ZnOthin films by plasma-enhanced atomic layer deposition, Appl.Phys.Lett, 102, 012113 (2013)) plasma enhanced atomic layer deposition technology is used to prepare zinc-oxide film, with the Al/PEALD-ZnO/Pt resistance-variable storing device of this film preparation, resistance ratio between its high-impedance state and low resistance state is greater than 10
3, but also there is resistive poor stability, the problem that high-impedance state change in resistance scope is large.
, also there is resistive poor stability in other film (as aluminium oxide, titanium oxide etc.) using ALD technology to prepare, erasable voltage is comparatively large, and the problems such as high-impedance state change in resistance scope is large, these all limit the extensive use of ALD technology in resistance-variable storing device field.
Summary of the invention
The invention provides a kind of preparation method of resistance-variable storing device, in the preparation process of the resistive dielectric layer of resistance-variable storing device, introduce a kind of brand-new in-situ plasma strengthen hot atom layer deposition techniques.The resistance-variable storing device prepared, can realize the accurate control to device resistance switching characteristic, finally reach to devices switch ratio, erasable voltage adjustable, and there is splendid resistive stability.
In-situ plasma of the present invention strengthens process, is that all carry out gaseous plasma to metal-oxide film and strengthen process, deposition cycle and the plasma process cycles of metal-oxide film hocket successively after each heat deposition circulation terminates.Described gas plasma process belongs to post-processing technology, and gaseous plasma does not participate in film deposition process, only affects surface topography and the defect of film.Can by controlling plasma generation power, processing time and plasma-generating gas component, flow, the concentration of fixing quantity plasma intermediate ion, electronics and free radical, and then defect kind, the concentration in control film, realize the resistance switch characteristic regulating resistance-variable storing device on a large scale.
The invention discloses a kind of preparation method of resistance-variable storing device, described resistance-variable storing device comprises hearth electrode, resistive dielectric layer material and the top electrode assembled successively, and the preparation of described resistive dielectric layer material comprises the following steps:
1) successively the first presoma, the first inert gas, the second presoma, the second inert gas are passed in reactor, through a circulation of pyrogen sublayer deposition, hearth electrode deposits one deck single metal oxide film;
2) plasma enhanced process is carried out to the single metal oxide film of step 1) deposition;
3) cycle alternation carries out above-mentioned step 1) and 2);
Ald requires that the first presoma has good volatility, thermal stability and reactivity when entering reactor, and the first described presoma is metal alkyl or metal alkoxide.As preferably, the first described presoma is diethyl zinc, trimethyl aluminium or titanium tetraisopropylate, and above three kinds of materials, as presoma, have sufficiently high vapour pressure, can ensure the surface covering hearth electrode fully; Meanwhile, form the chemisorbed layer of monolayer on hearth electrode surface, and the absorption that reaches capacity within shorter circulation timei.
In atomic layer deposition process, must pass into inert gas at different presoma impulses injection interval as carrier gas and cleaning reactor, isolate different presoma pulse, the first described inert gas and the second inert gas are same gas simultaneously.As preferably, in the present invention, adopt argon gas as the inert gas of cleaning reactor.
As preferably, argon gas is 20 mark condition ml/min (sccm) as the volume flow of carrier gas, under this flow, reactant unnecessary in reactor or accessory substance can be cleaned out within the suitable time.
In the sedimentation of pyrogen sublayer, all using water as the second presoma.
Resistive dielectric layer material is the core of RRAM, selects different materials, and the resistive characteristic of RRAM exists larger difference, and the material category with resistive characteristic reported at present is various.Described resistive dielectric layer material is metal-oxide film.Metal oxide have composition simple, be easy to preparation and with the advantage such as CMOS technology is compatible.As preferably, described metal oxide is ZnO, Al
2o
3or TiO
2.The film of these three kinds of metal oxides all has excellent resistance switch characteristic, and the ALD technology of preparing of film is simple, ripe, and deposition process can be carried out at low temperatures.
Metal oxide in the present invention is deposited directly on hearth electrode, and therefore base reservoir temperature is hearth electrode temperature, and described hearth electrode temperature is 50 ~ 400 DEG C, and as preferably, described hearth electrode temperature is 150 ~ 250 DEG C.Temperature is too high, and the metal-oxide film of precursors and reaction preparation easily decomposes or from surface desorption, affects deposition quality; Temperature is too low, and precursors is difficult to fully adsorb at matrix surface and react because of chemical absorption of surface and reaction barrier effect, even occurs the condensation of precursors, reduces reaction rate and affects deposition quality.
Described deposition pressure is 0.1 ~ 2 holder (Torr), and as preferably, described deposition pressure is ~ 1Torr.Deposition pressure affects the free path of the various active particles in plasma significantly.Air pressure is too low, and the free path of active particle is very long, is easy to destroy the membrane structure deposited, and even film bombardment is fallen; Air pressure is too high, and free path is too short, and particle activity is too low, is difficult to react with film.
Various active particles in plasma are made up of ion, electronics and plasma free radical, have higher reactivity, can react with film at low temperatures, the defect in regulation and control film.Plasma described in the present invention regulates and controls the defect in film by removal defect and introducing defect two kinds of modes, and then regulating and controlling the resistance switch characteristic of resistance-variable storing device on a large scale: oxygen gas plasma can effectively remove the defects such as hydrogen impurity, Lacking oxygen, thus the on-off ratio of boost device.Hydrogen, nitrogen and hydrogen mixture plasma can realize the effect to film note hydrogen, note nitrogen, thus generate such defect in the film; Suitably, the injection of qualitative deficiency, can on the basis maintaining certain on-off ratio, the stability of boost device, reduce erasable voltage.
When the first described presoma is diethyl zinc, described plasma is oxygen gas plasma, and the metal-oxide film prepared is ZnO film.Usually containing defects such as hydrogen impurity, Lacking oxygen in the ZnO film using hot atom layer deposition techniques to prepare, these defects make film resistor very little, thus cause device not have resistance switch characteristic or on-off ratio very little.And oxygen gas plasma can remove these defect and impurities effectively.By the process of oxygen gas plasma, the content of hydrogen impurity in film can be reduced, reduce the defects such as Lacking oxygen, improve the resistance of film, thus improve the on-off ratio of resistive memory; Along with the increase in processing power, gas flow, processing time, in film, hydrogen impurity reduces thereupon, and initial resistance increases thereupon, and devices switch is than promoting thereupon.
As preferably, the radio frequency source power of described plasma generation is 300 ~ 1000W; Further preferably, described power is 500W.When power is too small, in film, the minimizing of hydrogen impurity is few, and the on-off ratio of resistance-variable storing device promotes DeGrain; When power is excessive, plasma bombardment makes roughness of film significantly become large, have impact on the stability of device.Therefore, by the radio frequency source power of plasma preferably in above-mentioned scope.
As preferably, the flow of described plasma-generating gas is 30 ~ 200sccm; Further preferably, described flow is 60sccm.Increase with gas flow, in film, defect increases thereupon, if flow is excessive, is unfavorable for that plasma occurs, and on-off ratio also can be made significantly to decline simultaneously.
As preferably, the described plasma enhanced process time is 5 ~ 30s/ circulation; Further preferably, the described processing time is 20s/ circulation.Time too short when treated, the resistance-variable storing device on-off ratio of preparation is too small or do not have resistance switch characteristic; Processing time is long, and roughness of film significantly becomes large.Therefore, by the plasma enhanced process time preferably in above-mentioned scope.
As preferably, described cycle alternation number of times is 100 ~ 1500, and the thickness of gained ZnO film is 10 ~ 300nm.The thickness depositing the ZnO single thin film obtained by atomic heat is about
resistive thickness of dielectric layers in resistive memory is generally no more than 300nm, is therefore limited in above-mentioned scope by cycle alternation number of times.
Be the first presoma with diethyl zinc, when adopting oxygen gas plasma process, as preferably, the radio frequency source power of described plasma generation is 500W, the flow of plasma-generating gas is 60sccm, the plasma enhanced process time is 20s/ circulation time, and in the metal-oxide film obtained, defect content is in optimum value, the optimal stability of the resistance-variable storing device prepared.
When the first described presoma be trimethyl aluminium or titanium tetraisopropylate time, described plasma is hydrogen gas plasma or nitrogen and hydrogen mixture plasma, and the metal-oxide film prepared is Al
2o
3film or TiO
2film.Due to Al
2o
3and TiO
2initial resistance very big, the erasable voltage of the resistance-variable storing device prepared is also very big, causes the stability of device to decline.By the process of hydrogen gas plasma, more hydrogen impurity can be injected in the film, reduce film initial resistance, thus reduce the erasable voltage of resistive memory, improve the stability of device; Along with the increase in processing power, gas flow, processing time, in film, hydrogen impurity increases thereupon, and initial resistance reduces thereupon, and under the prerequisite maintaining certain on-off ratio, the erasable voltage of memory device reduces thereupon, and the stability of device promotes thereupon.By the process of nitrogen and hydrogen mixture plasma, nitrogen element can be injected in the film, form metal oxynitride, thus improve the stability of device; Along with the increase in processing power, gas flow, processing time, in film, nitrogen content increases thereupon, when nitrogen content is in a particular value, and the optimal stability of device.
As preferably, the radio frequency source power of described plasma generation is 100 ~ 800W; Further preferably, described power is 300W.Power is too small, and treatment effect is not obvious; Power is excessive, then on-off ratio significantly declines.
As preferably, the flow of described plasma-generating gas is 10 ~ 100sccm; Further preferably, described flow is 30sccm.Increase with gas flow, in film, defect increases thereupon, if flow is excessive, is unfavorable for that plasma occurs, and on-off ratio also can be made significantly to decline simultaneously.
As preferably, the described plasma enhanced process time is 3 ~ 15s/ circulation, and further preferably, the described processing time is 5s/ circulation.The trace that is introduced as of defect is introduced, and the processing time is long, then defect is introduced too much, and on-off ratio significantly declines.
Described cycle alternation number of times is 100 ~ 3000, and the thickness of gained metal-oxide film is 10 ~ 300nm.Increase with cycle-index, the thickness of metal-oxide film increases, and the monolayer film thickness of deposition is different with the kind of film.Resistive thickness of dielectric layers in resistive memory is generally no more than 300nm.General film is thicker, and initial resistance is larger, and on-off ratio is larger, but erasable voltage is higher.According to actual needs, by the thickness of metal-oxide film preferably in above-mentioned scope.
Be the first presoma with trimethyl aluminium or titanium tetraisopropylate, when adopting hydrogen gas plasma or nitrogen and hydrogen mixture plasma treatment, as preferably, the radio frequency source power of described plasma generation is 300W, the flow of plasma-generating gas is 30sccm, the plasma enhanced process time is 5s/ circulation time, and in the metal-oxide film obtained, defect content is in optimum value, the optimal stability of the resistance-variable storing device prepared.
The construction unit of resistance-variable storing device is followed successively by substrate, hearth electrode, resistive dielectric layer and top electrode from bottom to up.
Described substrate is dielectric substrate, is preferably SiO
2/ Si, glass, quartz or sapphire, the SiO that more preferably technique is simple, structure is ripe
2/ Si substrate.
Described hearth electrode material, requires that it does not react with plasma, has excellent conductivity simultaneously, and as preferably, described hearth electrode material is inert metal, and further preferably, described inert metal is Au or Pt.
As preferably, the method for electron beam evaporation or magnetron sputtering is adopted to prepare hearth electrode in substrate surface deposition.
The selection of top electrode will consider the factors such as the contact interface of stability of material, conductivity, work function, electrode and dielectric layer, described top electrode material is metal, as preferably, described metal is the one in metal Ti conventional in precious metals pt, Au, Ag or CMOS technology, Al.
As preferably, adopt photoetching, metal mask control electrode shape, adopt electron beam evaporation, the method for thermal evaporation or magnetron sputtering prepares top electrode in resistive dielectric layer surface deposition.
In conventional PEALD technology, gaseous plasma reacts as reactant and presoma, its concentration, kind and reaction time all can the growth rates of appreciable impact film, cannot effectively and regulate film defects on a large scale, be difficult to realize the regulation and control to resistance-variable storing device resistance switch characteristic.
Compared with the PEALD technology of routine, in the present invention, gaseous plasma reacts as the film of reactant and generation, and surface chemical reaction and defect Regulation Mechanism are different from PEALD technology completely.The preparation method that the present invention adopts can realize the resistance switch characteristic of adjusting means more broadly.
The invention provides a kind of preparation method of resistance-variable storing device, in the preparation process of the resistive dielectric layer of resistance-variable storing device, introduce a kind of brand-new in-situ plasma strengthen hot atom layer deposition techniques, fully combine the advantage of hot atom layer deposition techniques and plasma enhanced atomic layer deposition technology.
This technology accurately can control the thickness of metal-oxide film, and the film of preparation has high conformality, high-compactness, and can realize large-area uniformity; Meanwhile, strengthen process by in-situ plasma, the defect in metal-oxide film can be regulated on a large scale.
Resistance-variable storing device prepared by this method can realize the accurate control to device resistance switching characteristic, finally reach to devices switch ratio, erasable voltage adjustable, and there is splendid resistive stability.
Accompanying drawing explanation
Fig. 1 is existing resistance variation memory structure schematic diagram;
Fig. 2 is the preparation process schematic diagram of ZnO resistive dielectric layer in embodiment 1 and comparative example 1;
Fig. 3 is the resistance cumulative frequency distributing graph of the high and low resistance state of zno-based resistance-variable storing device prepared respectively in embodiment 1 and comparative example 1;
Fig. 4 is the resistivity-time variation diagram of the high and low resistance state of zno-based resistance-variable storing device prepared respectively in embodiment 1 and comparative example 1.
In Fig. 1: 11-top electrode, 12-resistive dielectric layer, 13-hearth electrode, 14-substrate;
In Fig. 2:
The preparation process of ZnO resistive dielectric layer in (a) embodiment 1;
The preparation process of ZnO resistive dielectric layer in (b) comparative example 1;
In Fig. 3:
The high-resistance resistors cumulative frequency distribution of zno-based resistance-variable storing device prepared by 31-embodiment 1;
The low resistance state resistance cumulative frequency distribution of zno-based resistance-variable storing device prepared by 32-embodiment 1;
The high-resistance resistors cumulative frequency distribution of zno-based resistance-variable storing device prepared by 33-comparative example 1;
The low resistance state resistance cumulative frequency distribution of zno-based resistance-variable storing device prepared by 34-comparative example 1;
In Fig. 4:
The resistivity-time change curve of zno-based resistance-variable storing device high-impedance state prepared by 41-embodiment 1;
The resistivity-time change curve of zno-based resistance-variable storing device low resistance state prepared by 42-embodiment 1;
The resistivity-time change curve of zno-based resistance-variable storing device high-impedance state prepared by 43-comparative example 1;
The resistivity-time change curve of zno-based resistance-variable storing device low resistance state prepared by 44-comparative example 1.
Embodiment
Embodiment 1
1) adopt magnetically controlled sputter method at SiO
2(300nm)/Si (100) substrate surface prepares inert metal Pt hearth electrode, and gained hearth electrode thickness is 150nm, and the temperature of preparation is 150 DEG C, deposits that main gas is argon gas, pressure is 0.5Pa, and sputtering power is 300W.
2) in-situ plasma is adopted to strengthen pyrogen sublayer sedimentation, using diethyl zinc as the first presoma, steam is the second presoma, argon gas is purge gas, on Pt hearth electrode, the zinc-oxide film of one deck individual layer is first formed after the deposition of pyrogen sublayer, then oxygen gas plasma is utilized to carry out in-situ plasma treatment to this film, repeat 250 circulations, finally obtain zinc-oxide film, the thickness of this film is about 42nm.The temperature of Pt hearth electrode is 150 DEG C; Argon carrier flow is 20sccm; Deposition and process air pressure are 1Torr; The radio frequency source power of plasma generator is 500W; Oxygen gas plasma flow is 60sccm, and the processing time is 20s/ circulation.
3) utilize magnetically controlled sputter method at the circular Al top electrode of ZnO film surface preparation, the thickness of top electrode is about 100nm, and diameter is 200um.The temperature of preparation is 25 DEG C, deposits that main gas is argon gas, pressure is 0.5Pa, and sputtering power is 300W.
Comparative example 1
1) adopt magnetically controlled sputter method at SiO
2(300nm)/Si (100) substrate surface prepares inert metal hearth electrode Pt, and gained hearth electrode thickness is 150nm, and the temperature of preparation is 150 DEG C, deposits that main gas is argon gas, pressure is 0.5Pa, and sputtering power is 300W.
2) adopt hot atom layer deposition techniques, using diethyl zinc as the first presoma, steam as the second presoma, argon gas is purge gas, after 250 circulations, obtains the zinc-oxide film that thickness is about 42nm.The temperature of Pt hearth electrode is 150 DEG C; Argon carrier flow is 20sccm; Deposition and process air pressure are 1Torr.
3) oxygen plasma is used to step 2) zinc-oxide film that obtains carries out ex situ process; Deposition and process air pressure are 1Torr; The temperature of Pt hearth electrode is 150 DEG C; Radio frequency source power is 500W; Oxygen gas plasma flow is 60sccm, and the processing time is 250 × 20s.
4) utilize magnetically controlled sputter method to prepare circular top electrode A l at film surface, thickness of electrode is about 100nm, and electrode diameter is 200um.The temperature of preparation is 25 DEG C, deposits that main gas is argon gas, pressure is 0.5Pa, and sputtering power is 300W.
Comparing embodiment 1 and comparative example 1 can find, the two all has ambipolar resistance switch characteristic, and the on-off ratio of resistance-variable storing device is all greater than 100 times.Fig. 3 is the test of resistive memory cyclical stability, and wherein, curve 31,32 is respectively the high and low resistance state resistor value of device described in embodiment 1, the high and low resistance state resistor value that curve 33,34 is device described in comparative example 1; The device information holding time is more than 10
4in s, Fig. 4, curve 41,42 is respectively the high and low resistance state change curve in time of device described in embodiment 1, and curve 43,44 is the high and low resistance state of device change curve in time described in comparative example 1.Device meets the instructions for use of resistance-variable storing device.Through 100 loop tests, the film resistance switches that the original position oxygen plasma treatment that embodiment 1 adopts obtains is 3 times of non-in-situ treatment film than mean value, and large on-off ratio demonstrates in-situ treatment method and is better than ex situ process.
Embodiment 2
1) adopt magnetically controlled sputter method at SiO
2(300nm)/Si (100) substrate surface prepares inert metal Pt hearth electrode, and gained hearth electrode thickness is 150nm, and the temperature of preparation is 150 DEG C, deposits that main gas is argon gas, pressure is 0.5Pa, and sputtering power is 300W.
2) in-situ plasma is adopted to strengthen pyrogen sublayer sedimentation, using diethyl zinc as the first presoma, steam is the second presoma, argon gas is purge gas, on Pt hearth electrode, the zinc-oxide film of one deck individual layer is first formed after the deposition of pyrogen sublayer, then oxygen gas plasma is utilized to carry out in-situ plasma treatment to this film, repeat 250 circulations, finally obtain zinc-oxide film, the thickness of this film is about 42nm.The temperature of Pt hearth electrode is 150 DEG C; Argon carrier flow is 20sccm, and deposition and the process air pressure of reaction chamber are 1Torr, and oxygen gas plasma flow is 60sccm.
3) regulate the radio frequency source power of plasma generator to be 300,500,800W; The oxygen gas plasma processing time is fixed as 20s/ circulation.Utilize magnetically controlled sputter method at the circular Al top electrode of ZnO film surface preparation, the thickness of top electrode is about 100nm, and diameter is 200um.The temperature of preparation is 25 DEG C, deposits that main gas is argon gas, pressure is 0.5Pa, and sputtering power is 300W.
4) the radio frequency source power of plasma generator is fixed as 500W; Regulate the oxygen gas plasma processing time to be 0,5,10,15,20s/ circulation.Utilize magnetically controlled sputter method at the circular Al top electrode of ZnO film surface preparation, the thickness of top electrode is about 100nm, and diameter is 200um.The temperature of preparation is 25 DEG C, deposits that main gas is argon gas, pressure is 0.5Pa, and sputtering power is 300W.
The thin-film device obtained through step 3) process all has ambipolar resistance switch characteristic, and the thin-film device on-off ratio through 300W process is only greater than 50 times; Its on-off ratio of device through 500W and 800W process is all greater than 100 times.
Through the thin-film device that step 4) process obtains, the device of 0s and 5s process does not have resistance switch characteristic; The device of 10s, 15s, 20s process demonstrates ambipolar resistance switch characteristic, and its on-off ratio of the device of 10s and 15s process only has tens times, and the device after 10s process is after 20 times erasable, and device resistance switch performance disappears; Through the device of 20s process, in film, the defect such as hydrogen impurity, Lacking oxygen significantly reduces, and devices switch ratio is greater than 100 times.
Embodiment 3
Adopt hot atom layer deposition techniques to prepare aluminum oxide film resistance-variable storing device, and use hydrogen gas plasma to carry out in-situ treatment, comprise the following steps:
1) adopt magnetically controlled sputter method at SiO
2(300nm)/Si (100) substrate surface prepares inert metal hearth electrode Pt, and gained hearth electrode thickness is 150nm, and the temperature of preparation is 150 DEG C, deposits that main gas is argon gas, pressure is 0.5Pa, and sputtering power is 300W.
2) technique for atomic layer deposition is adopted, using trimethyl aluminium as the first presoma, steam is the second presoma, argon gas is purge gas, on Pt hearth electrode, the aluminum oxide film of one deck individual layer is first formed after the deposition of pyrogen sublayer, then hydrogen gas plasma is utilized to carry out in-situ plasma treatment to this film, repeat 200 circulations, finally obtain aluminum oxide film, the thickness of this film is about 20nm.The temperature of Pt hearth electrode is 300 DEG C; Argon carrier flow is 20sccm; Deposition and process air pressure are 1Torr; The radio frequency source power of plasma generator is 300W; Hydrogen flowing quantity is 30sccm, and the processing time is 5s/ circulation.
3) adopt magnetically controlled sputter method to prepare circular top electrode Ti at film surface, thickness of electrode is about 100nm, and electrode diameter is 200um.The temperature of preparation is 25 DEG C, deposits that main gas is argon gas, pressure is 0.5Pa, and sputtering power is 300W.
Undressed aluminum oxide film film resistance is very large, and ~ 10
9Ω.After carrying out hydrogen plasma process, film initial resistance reduces 2 ~ 3 orders of magnitude.After an electro activation process, device demonstrates ambipolar resistance switch characteristic.Now, film thickness is substantially constant compared with untreated, but activation voltage is reduced to 4 ~ 6V by 6 ~ 8V.Device after electro activation is tested through 100 cyclical stabilities, the resistance switch ratio of device is greater than 100 times, after process, device stability is improved, and write voltage range is reduced to 0.5 ~ 1.7V by 0.6 original ~ 3V, and erasing voltage scope becomes-0.8V ~-2.2V from-1V ~-3V.
Embodiment 4
Adopt hot atom layer deposition techniques to prepare thin film of titanium oxide resistance-variable storing device, and use ammonia plasmas to carry out in-situ treatment, comprise the following steps:
1) adopt magnetically controlled sputter method at SiO
2(300nm)/Si (100) substrate surface prepares inert metal hearth electrode Pt, and gained hearth electrode thickness is 150nm, and the temperature of preparation is 150 DEG C, deposits that main gas is argon gas, pressure is 0.5Pa, and sputtering power is 300W.
2) technique for atomic layer deposition is adopted, using titanium tetraisopropylate as the first presoma, steam is the second presoma, argon gas is purge gas, on Pt hearth electrode, the thin film of titanium oxide of one deck individual layer is first formed after the deposition of pyrogen sublayer, then ammonia plasmas is utilized to carry out in-situ plasma treatment to this film, repeat 2000 circulations, finally obtain thin film of titanium oxide, the thickness of this film is about 40nm.The temperature of Pt hearth electrode is 250 DEG C; Argon carrier flow is 20sccm; Deposition and process air pressure are 1Torr; The radio frequency source power of plasma generator is 300W; Nitrogen and hydrogen mixture (1:1) flow is 30sccm, and the processing time is 5s/ circulation.
3) adopt magnetically controlled sputter method to prepare circular top electrode Pt at film surface, thickness of electrode is about 100nm, and electrode diameter is 200um.The temperature of preparation is 25 DEG C, deposits that main gas is argon gas, pressure is 0.5Pa, and sputtering power is 300W.
After carrying out nitrogen and hydrogen mixture plasma treatment to thin film of titanium oxide, film becomes the titanium oxynitrides film containing trace nitrogen.The conductivity of titanium oxynitrides is better than thin film of titanium oxide, makes the thin-film device through in-situ treatment no longer need electro activation process, can realize reversible monopole type resistance switch characteristic.Device stability is improved, and write voltage becomes 1.1 ~ 1.6V from 1.6 ~ 3.1V, and erasing voltage becomes 0.4 ~ 0.8V from 0.4 ~ 1V.
It should be noted that, above-described embodiment is only not used in for illustration of the present invention and limits the scope of the invention.In addition should be understood that those skilled in the art can make various changes or modifications the present invention, and these equivalent form of values fall within the application's appended claims limited range equally after the content of having read the present invention's instruction.
Claims (2)
1. a preparation method for resistance-variable storing device, described resistance-variable storing device comprises hearth electrode, resistive dielectric layer material and the top electrode assembled successively, it is characterized in that, the preparation of described resistive dielectric layer material comprises the following steps:
1) successively the first presoma, the first inert gas, the second presoma, the second inert gas are passed in reactor, through a circulation of pyrogen sublayer deposition, hearth electrode deposits one deck single metal oxide film;
2) to step 1) the single metal oxide film that deposits carries out plasma enhanced process;
3) cycle alternation carries out above-mentioned step 1) and 2);
The first described presoma is diethyl zinc, and described plasma is oxygen gas plasma, and the radio frequency source power of plasma generation is 100 ~ 800W; The flow of described plasma-generating gas is 10 ~ 100 mark condition ml/min; The described plasma enhanced process time is 3 ~ 15s/ circulation;
Or the first described presoma is trimethyl aluminium or titanium tetraisopropylate, described plasma is hydrogen gas plasma or nitrogen and hydrogen mixture plasma, and the radio frequency source power of plasma generation is 300 ~ 1000W; The flow of described plasma-generating gas is 30 ~ 200 mark condition ml/min; The described plasma enhanced process time is 5 ~ 30s/ circulation.
2. the preparation method of resistance-variable storing device according to claim 1, is characterized in that, described hearth electrode material is inert metal, and described inert metal is Au or Pt.
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| CN104037323A (en) * | 2014-06-16 | 2014-09-10 | 浙江大学 | Preparation method of RRAM (Resistive Random Access Memory) |
| CN104103756B (en) * | 2014-07-25 | 2018-05-04 | 福州大学 | A kind of resistance-variable storing device and the method that multilevel storage is realized using it |
| CN105932154B (en) * | 2016-05-17 | 2018-10-09 | 浙江师范大学 | Material with stable threshold resistance transformation characteristic and dynamic RAM part |
| TWI635539B (en) * | 2017-09-15 | 2018-09-11 | 金巨達國際股份有限公司 | High-k dielectric layer, fabricating method thereof and multifunction equipment implementing such fabricating method |
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