CN101162759A - Memory cell of nitridation titanium/zinc oxide resistor type stochastic memory and preparation method - Google Patents
Memory cell of nitridation titanium/zinc oxide resistor type stochastic memory and preparation method Download PDFInfo
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- CN101162759A CN101162759A CNA2007101767504A CN200710176750A CN101162759A CN 101162759 A CN101162759 A CN 101162759A CN A2007101767504 A CNA2007101767504 A CN A2007101767504A CN 200710176750 A CN200710176750 A CN 200710176750A CN 101162759 A CN101162759 A CN 101162759A
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Abstract
The present invention provides a storage location of a resistance type random access memory and a method for preparing the same, and belongs to the micro-electronics semiconductor technical field. The storage location comprises a substrate and a metal-insulator-metal (MIM) structure resistor; the top electrode of the MIM structure resistor is made of titanium nitride; the insulator is a zinc oxide film. As the invention adopts the titanium nitride/ zinc oxide composite structure, the invention appears excellent conversion between a high resistance state and a low resistance state and the memory property in the continuous scanning drive. The invention also further provides the method for preparing the storage location, comprising the following procedures: silicon dioxide or silicon is chose as the substrate material; a bottom electrode is prepared on the substrate by the sputtering method; a zinc oxide film is prepared on the bottom electrode; a titanium nitride film is prepared on the zinc oxide film by the sputtering method; the titanium nitride film is prepared into an electrode pattern by the photoetching and etching method; finally a part structure is prepared by the wet etching method or the dry etching method on the basis of the structure achieved in the previous procedure.
Description
Technical field
The present invention relates to technical field of non-volatile, relate in particular to and a kind ofly have that excellent bistable resistive changes and the memory cell of the resistor type random access memory of memory characteristic and preparation method thereof.
Background technology
Non-volatility memorizer has the advantage that still can keep data message when non-transformer is supplied, and has important status at area information storage, also is one of research focus of current information memory technology.Yet there are problems such as operating voltage height, speed are slow, endurance difference in current main flow nonvolatile memory-flash memory (flash).It is fast that resistor type random access memory RRAM (Resistive Random Access Memory) has shown operating rate, the storage density height, and advantage such as data hold time is long, and endurance is strong is the strong candidate of semiconductor memory of future generation.The basic unit of storage of RRAM comprises a metal-insulator-metal type (MIM) structural resistance device.By voltage or current impulse, the resistance of mim structure is changed, between high low resistance state to realize writing and wiping of data.The key of RRAM work is the electric resistance changing and the memory effect of some material, and reversible, huge change can take place the resistance of these materials under the voltage or the function of current.
Many kinds of transition metal oxide semiconductive thin films are such as TiO
2, NiO and Cu
xO etc. have shown electric resistance changing and memory characteristic.These materials have simple diadactic structure, are easy to current traditional semiconductor device fabrication processes integratedly, have caused people's extensive studies interest.Resistive memory device for reality is used, avoid the high-pressure process in the electric forming, reduce programming (Set-V) and wipe (reset-V) voltage, promote the erasable speed of memory cell, the data hold time of prolongation memory cell and enhancing reliability etc. is very important.At present, how the basic unit of storage of RRAM has that excellent bistable resistive changes and memory characteristic is a problem demanding prompt solution.
Summary of the invention
The object of the present invention is to provide and a kind ofly have that excellent bistable resistive changes and the memory cell of the resistor type random access memory spare of memory characteristic and preparation method thereof.Above-mentioned purpose of the present invention is achieved by the following technical solutions:
A kind of memory cell of titanium nitride/zinc oxide resistor type stochastic memory comprises: substrate and metal-insulator-metal type (MIM) structural resistance device, and wherein, the top electrode of mim structure resistor is a titanium nitride, insulator is a zinc-oxide film.
Zinc-oxide film can mix following element, hafnium (Hf), cobalt (Co), nickel transition metal such as (Ni) or aluminium main group metals such as (Al).Hearth electrode is platinum/titanium (Pt/Ti), gold/titanium (Au/Ti), titanium (Ti), tungsten (W), tantalum (Ta).
A kind of memory cell preparation method of resistor type random access memory, its step comprises:
1) selecting silicon dioxide or silicon is backing material, utilizes sputtering method to prepare hearth electrode on substrate;
2) on above-mentioned hearth electrode, prepare zinc-oxide film;
3) utilize sputtering method on zinc-oxide film, to prepare titanium nitride membrane, and utilize the method for photoetching, etching that described titanium nitride membrane is prepared electrode pattern, as top electrode;
4) utilize the method for wet etching or dry etching on the acquired architecture basics of previous step, to prepare the device architecture of isolation.
In the step 1, the method for utilizing thermal oxidation and chemical vapor deposition (CVD) with silicon dioxide spacer medium layer growth on monocrystalline silicon, as substrate.
In the step 1, utilize sputtering method to prepare metallic film on substrate, metallic film is platinum/titanium alloy, gold/titanium alloy, titanium, tungsten, tantalum or titanium nitride.
In the step 2, the preparation method of zinc-oxide film adopts reactive sputtering, and actual conditions is: (for reactive sputtering) atmosphere argon/oxygen atmosphere, the ratio of argon/oxygen atmosphere is 5: 1, sputtering power 500W.The thickness scope of zinc oxide: 20-50nm.In sputter procedure, can use the main target (zinc) of different materials, secondary target (hafnium, aluminium, nickel etc.), cosputtering is realized the purpose of mixing.The zinc oxide of the film of preparation for mixing.Also can adopt atomic layer deposition (ALD), sol-gel process (Sol-gel), metal-organic chemical gaseous phase are formed sediment and are hit (MOCVD), the perhaps method of thermal oxidation behind the splash-proofing sputtering metal zinc.
After the step 2, carry out annealing in process for zinc-oxide film, actual conditions is: temperature range is the 400-500 degree, and atmosphere is under air atmosphere or the vacuum, and vacuum degree is≤10
-3Pa or nitrogen/oxygen atmosphere, the ratio of nitrogen/oxygen atmosphere are 4: 1.The film that this step finishes the back growth is the zinc-oxide film ZnO of (non-) stoicheiometry
x, the scope of x is 1-2.
In the step 3, utilize the method for reactive sputtering to prepare titanium nitride membrane on zinc-oxide film, actual conditions is: the voltage ratio of argon gas and nitrogen is 18: 2, and vacuum degree is 5 * 10
-7Torr, sputtering power 500W.Titanium nitride thickness is 50-200nm.
In the step 3, utilize the method for reactive ion etching to finish electrode definition, actual conditions is: sulphur hexafluoride is 30sccm:20sccm with the helium gas flow ratio, and operating pressure is 8 * 10
-2Torr, etching power 100W
In the step 4, utilize the method for wet etching zinc oxide to prepare the isolating device structure, actual conditions is: after the first water-bath, and the buffered hydrofluoric acid with 5%, room temperature.Also can directly use RIE, the method for dry etchings such as ICP.
The present invention has the advantage of the following aspects:
The memory cell of resistor type random access memory of the present invention adopts titanium nitride/zinc oxide combining structure, and characteristic is than using common metal/zinc oxide separately or using the combination of titanium nitride/other oxides more excellent separately.Show transformation and memory characteristic between the excellent high low resistance state under direct voltage continuous sweep excitation, the difference between its high low resistance state can be greater than 10
2Doubly, the erasable electric forming process that all do not need of all devices.The cut-in voltage that its high-impedance state changes to low resistance state is less than+1.4V, and the recovery voltage that low resistance state changes to high-impedance state is less than-1.4V.Data hold time after the device outage is greater than 10
5Second, data remain on 10 under 500mV stress applies
4More than second.High-impedance state changes to low resistance state can use 20ns, and the pulse of 4V realizes; Low resistance state changes to high-impedance state can use 60ns, and the pulse of-4V realizes.These characteristics show that the present invention has potential using value in non-volatility memorizer spare field.
Description of drawings
Below in conjunction with accompanying drawing the present invention is illustrated in further detail:
The device architecture schematic diagram of the memory cell of Fig. 1 resistor type random access memory of the present invention;
The bipolar I-V characteristic test result of Fig. 2 resistor type random access memory of the present invention;
The change curve of the electric current of the memory cell high resistance and low resistance attitude of resistor type random access memory of the present invention under Figure 30 .5V constant stress;
Figure 40 .5V reads the change curve with the direct current erase-write cycles of resistance value of the memory cell high resistance and low resistance attitude of resistor type random access memory of the present invention under the voltage;
The pulse respond of Fig. 5 resistor type random access memory of the present invention reads pulse duration 50ns, 0.5V.
Embodiment
Below with reference to accompanying drawing of the present invention, more detailed description goes out most preferred embodiment of the present invention.
With reference to figure 1, the method for utilizing thermal oxidation and chemical vapor deposition (CVD) is with SiO
2 Spacer medium layer 4 is grown on the monocrystalline silicon 5, as substrate, utilize sputtering method to prepare Pt/Ti (100nm/20nm) as hearth electrode 3, utilize reactive sputtering on hearth electrode, to prepare ZnO film 2 again, thickness range (20-40nm), this film is carried out annealing in process under 450 ℃, annealing at nitrogen oxygen than being to carry out under 4/1 the atmosphere.Utilize X-ray diffraction method to measure the structure of film, find that ZnO film presents the plumbous zinc ore structure of six sides, (002) crystal orientation.Utilize the method for sputter, photoetching and etching to make TiN top electrode 1 on ZnO film, electrode size does not wait from 5um to 200um.
With reference to figure 2, Fig. 3, utilize Agilent 4156C analyzing parameters of semiconductor tester to test the I-E characteristic of device.Under voltage continuous sweep pattern, tested the I-E characteristic of this device.Scan bias voltage is added on top electrode test probe and the platinum substrate.The I-E characteristic test result is seen Fig. 2.When 0V began to scan, this device showed the high resistant characteristic to voltage for the first time, and device changes low resistance state suddenly into when voltage is higher than 1.2V (cut-in voltage), needed this moment to set a current limitation value (being 5mA in this example), in order to avoid the excessive damage device of electric current.When voltage again when 1.2V is scanned up to 0V, device remains on low resistance state.Voltage begins to be scanned up to from 0V-and device changes high-impedance state into during 1.4V (recovery voltage).When voltage from-when 1.4V was scanned up to 0V, device remained on high-impedance state.In the device that all were tested, do not need the electric forming process, mean and in very low voltage range, to finish the read-write operation of this device.The transition process of this high low resistance state can repeat, and the transition curve of 500 high low resistance state has been shown among Fig. 3.In 500 change-over periods, the high low resistance state ratio worst case of device shows that still more than 10 times it has good durability.Provided the device height among Fig. 4, the retention performance of low two configurations, under the effect of 500mV constant stress, by the device current of flowing through is sampled, the resistance of observing device is 10
4The extremely small variation of interior generation.Fig. 5 utilizes Agilent54622D mixed signal oscilloscope and the test of Agilent33250A function generator, has provided the erasable characteristic of pulse of device: 4V, and the pulse of 20ns is opened into low resistance state with device from high-impedance state;-4V, the pulse of 60ns returns to high-impedance state with device from low resistance state, has shown the variation of electric current in the circuit of program/erase front and back among the figure.
The foregoing description is of the present invention giving an example, although disclose most preferred embodiment of the present invention and accompanying drawing for the purpose of illustration, but it will be appreciated by those skilled in the art that: without departing from the spirit and scope of the invention and the appended claims, various replacements, variation and modification all are possible.Therefore, the present invention should not be limited to most preferred embodiment and the disclosed content of accompanying drawing.
Claims (10)
1. the memory cell of a titanium nitride/zinc oxide resistor type stochastic memory, comprise: substrate and metal-insulator-metal type mim structure resistor, it is characterized in that: the top electrode of mim structure resistor is a titanium nitride, and insulator is the zinc-oxide film ZnO of non-chemical proportion
x, the scope of x is 1-2.
2. the memory cell of titanium nitride/zinc oxide resistor type stochastic memory as claimed in claim 1 is characterized in that: the hafnium that mixes in zinc-oxide film, cobalt or nickel transition metal or aluminium main group metal.
3. the memory cell of titanium nitride/zinc oxide resistor type stochastic memory as claimed in claim 1 or 2, it is characterized in that: the hearth electrode of mim structure resistor is platinum/titanium alloy, gold/titanium alloy, titanium, tungsten or tantalum.
4. the memory cell of titanium nitride/zinc oxide resistor type stochastic memory as claimed in claim 1 or 2, it is characterized in that: the thickness range of insulator oxide zinc film is 20nm-50nm.
5. the preparation method of a resistor type random access memory memory cell, its step comprises:
1) selecting silicon dioxide or silicon is backing material, prepares hearth electrode on substrate;
2) on hearth electrode, prepare zinc-oxide film;
3) utilize sputtering method on sull, to prepare titanium nitride membrane, utilize the method for photoetching, etching that described titanium nitride membrane is prepared electrode pattern, as top electrode;
4) utilize the method for wet etching or dry etching on the acquired architecture basics of previous step, to prepare the device architecture of isolation.
6. preparation method as claimed in claim 5, it is characterized in that: in the step 2, the preparation method of zinc-oxide film adopts reactive sputtering, actual conditions is: atmosphere argon/oxygen atmosphere, the ratio of argon/oxygen atmosphere is 5: 1, and sputtering power 500W is in sputter procedure, use main target zinc and secondary target hafnium, aluminium or nickel cosputtering.
7. preparation method as claimed in claim 6 is characterized in that: zinc-oxide film is carried out annealing in process, and actual conditions is: temperature range is the 400-500 degree, and atmosphere is under air atmosphere or the vacuum, and vacuum degree is≤10
-3Pa or nitrogen/oxygen atmosphere, the ratio of nitrogen/oxygen atmosphere are 4: 1.
8. as claim 5 or 6 described preparation methods, it is characterized in that: in the step 3, utilize the method for reactive sputtering to prepare titanium nitride membrane on zinc-oxide film, actual conditions is: the voltage ratio of argon gas and nitrogen is 18: 2, and vacuum degree is 5 * 10
-7Torr, sputtering power 500W.
9. preparation method as claimed in claim 5 is characterized in that: in the step 3, utilize the method for reactive ion etching to finish electrode definition, actual conditions is: sulphur hexafluoride is 30sccm: 20sccm with the helium gas flow ratio, and operating pressure is 8 * 10
-2Torr, etching power 100W.
10. preparation method as claimed in claim 5 is characterized in that: in the step 4, utilize the method for wet etching zinc oxide to prepare the isolating device structure, actual conditions is: after the first water-bath, and the buffered hydrofluoric acid with 5%, room temperature.
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| CNA2007101767504A CN101162759A (en) | 2007-11-02 | 2007-11-02 | Memory cell of nitridation titanium/zinc oxide resistor type stochastic memory and preparation method |
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| CNA2007101767504A CN101162759A (en) | 2007-11-02 | 2007-11-02 | Memory cell of nitridation titanium/zinc oxide resistor type stochastic memory and preparation method |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102496631A (en) * | 2011-11-25 | 2012-06-13 | 中山大学 | ZnO-based full transparent non-volatile memory with back electrode structure and preparation method thereof |
| CN102738391A (en) * | 2012-06-07 | 2012-10-17 | 清华大学 | Resistance random access memory with adjustable dielectric layer magnetic property |
| CN102034927B (en) * | 2009-09-25 | 2012-11-28 | 中芯国际集成电路制造(上海)有限公司 | Impedance memorizer and manufacture method thereof |
| CN105679363A (en) * | 2016-01-18 | 2016-06-15 | 南昌大学 | Nonvolatile multi-bit micro/nanometer memory for storing temperature signals and application |
| CN108831992A (en) * | 2018-04-24 | 2018-11-16 | 湖北大学 | A kind of resistance-variable storing device and preparation method thereof of hafnium doping zinc-oxide change resistance layer |
-
2007
- 2007-11-02 CN CNA2007101767504A patent/CN101162759A/en active Pending
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102034927B (en) * | 2009-09-25 | 2012-11-28 | 中芯国际集成电路制造(上海)有限公司 | Impedance memorizer and manufacture method thereof |
| CN102496631A (en) * | 2011-11-25 | 2012-06-13 | 中山大学 | ZnO-based full transparent non-volatile memory with back electrode structure and preparation method thereof |
| CN102496631B (en) * | 2011-11-25 | 2014-05-21 | 中山大学 | ZnO-based full transparent non-volatile memory with back electrode structure and preparation method thereof |
| CN102738391A (en) * | 2012-06-07 | 2012-10-17 | 清华大学 | Resistance random access memory with adjustable dielectric layer magnetic property |
| CN102738391B (en) * | 2012-06-07 | 2014-07-16 | 清华大学 | Resistance random access memory with adjustable dielectric layer magnetic property |
| CN105679363A (en) * | 2016-01-18 | 2016-06-15 | 南昌大学 | Nonvolatile multi-bit micro/nanometer memory for storing temperature signals and application |
| CN108831992A (en) * | 2018-04-24 | 2018-11-16 | 湖北大学 | A kind of resistance-variable storing device and preparation method thereof of hafnium doping zinc-oxide change resistance layer |
| CN108831992B (en) * | 2018-04-24 | 2020-12-18 | 湖北大学 | Resistive random access memory with hafnium-doped zinc oxide resistive layer and preparation method thereof |
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