CN106941129A - A kind of GeTe/Bi for low power consumption phase changing memory2Te3Superlattice structure storage medium - Google Patents
A kind of GeTe/Bi for low power consumption phase changing memory2Te3Superlattice structure storage medium Download PDFInfo
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- CN106941129A CN106941129A CN201710035000.9A CN201710035000A CN106941129A CN 106941129 A CN106941129 A CN 106941129A CN 201710035000 A CN201710035000 A CN 201710035000A CN 106941129 A CN106941129 A CN 106941129A
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- storage medium
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Classifications
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N70/00—Solid-state devices without a potential-jump barrier or surface barrier, and specially adapted for rectifying, amplifying, oscillating or switching
- H10N70/801—Constructional details of multistable switching devices
- H10N70/881—Switching materials
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11C—STATIC STORES
- G11C13/00—Digital stores characterised by the use of storage elements not covered by groups G11C11/00, G11C23/00, or G11C25/00
- G11C13/0002—Digital stores characterised by the use of storage elements not covered by groups G11C11/00, G11C23/00, or G11C25/00 using resistive RAM [RRAM] elements
- G11C13/0004—Digital stores characterised by the use of storage elements not covered by groups G11C11/00, G11C23/00, or G11C25/00 using resistive RAM [RRAM] elements comprising amorphous/crystalline phase transition cells
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N70/00—Solid-state devices without a potential-jump barrier or surface barrier, and specially adapted for rectifying, amplifying, oscillating or switching
- H10N70/801—Constructional details of multistable switching devices
- H10N70/881—Switching materials
- H10N70/882—Compounds of sulfur, selenium or tellurium, e.g. chalcogenides
- H10N70/8828—Tellurides, e.g. GeSbTe
Abstract
A kind of GeTe/Bi for low power consumption phase changing memory of the present invention2Te3Superlattice structure storage medium.GeTe/Bi2Te3Superlattice structure storage medium includes at least one Bi2Te3Layer and GeTe material layers stack Bi between unit, adjacent cells2Te3Layer and GeTe material layers are arranged alternately；Bi2Te3Layer thickness range is 10~50 angstroms, and GeTe layers of thickness range are 10~25 angstroms；Bi2Te3Layer includes some Bi2Te3Unit, adjacent Bi2Te3Acted on and combined by van der waals between unit.Bi2Te3The application of/GeTe superlattice structures can more effectively reduce phase-change memory device power consumption.
Description
Technical field
The present invention relates to a kind of GeTe/Bi for low power consumption phase changing memory2Te3Superlattice structure storage medium.
Technical background
Phase change memory technology is can based on the Ovshinsky phase-change thin films proposed at beginning of the seventies late 1960s
Set up with the conception applied to phase change memory medium, be a kind of stable memory device of cheap, performance.Phase transformation is deposited
Reservoir can be made in silicon wafer substrate, its critical material be recordable phase-change thin film, heating electrode material, heat-insulating material and
Extraction electrode material etc..The general principle of phase transition storage is to be acted on using electric impulse signal on device cell, makes phase transformation material
Reversible transition occurs between amorphous state and polycrystalline state for material, can by differentiating low-resistance when high resistant and the polycrystalline state during amorphous state
To realize the write-in, erasing and read operation of information.
Phase transition storage produces Joule heat using operation signal and phase-change material is operated, and makes it between different phases
Changed, so as to embody high low-resistance value difference, and then completed the storage to information.Phase transition storage is due to its operation speed
Degree is fast, and data retention is good, and circulate operation ability is strong, compatible with traditional cmos process, and remain in small size holding its
Operating characteristics, so being considered as one of most promising non-volatility memorizer of future generation.It is low with the diminution of device size
Power consumption is still the focus and difficult point of present phase transition storage research.
Simpson in 2011 proposes interfacial phase change memory concept.Information Store is changed by interface atomic structure
Complete, this structure change is a solid-state phase changes process.Need storage being situated between compared to traditional phase transition storage storage medium
Matter melt quenching enters row information write-in, and the atom variable number that solid-state phase changes are related to is few, and do not need a person with the qualifications of a general material fusing, makes information
Energy needed for write-in significantly reduces.So the operation signal needed for interface storage compares conventional phase change memory, with electricity
Force down the characteristics of electric current is small.Simultaneously because phase change memory medium is avoided during signal is erasable melts this pyroprocess,
The diffusion of storage medium interior element is improved, and the service life of memory device is increased dramatically.The excessive behaviour of phase transition storage
It is to limit its wide variety of principal element as electric current, transistor current driving force corresponding to memory cell is challenged.
This small feature of operation electric current of interface storage can effectively solve this problem.
Understanding to interface storage low-power consumption is gradually clear with going deep into for scientific research.Interface storage is by storage
The fine structure degree classification superlattices memory and superlattices memory of medium.The storage medium of class superlattices memory is by more
Layer phase-change material composition, due to the presence at interface, the thermal conductivity of material is reduced, and improves the thermal efficiency of storage medium, so that
The lower power consumption of memory.But class superlattice structure storage medium includes up to a hundred layers of atom of tens layers per layer material, data are write
Enter to still need to by melt material process, all Atomic Arrangements are readjusted.Its advantage, which is mainly derived from the multiple interfaces of introducing, to be caused
The thermal efficiency improve so that the energy needed for reducing operation signal.The storage medium of superlattices memory is using atomic layer to be single
Based on the artificial design arrangement of position, heterogeneous interface both sides can only allow limited differences between lattice constant, and material deposition process becomes
Nearly epitaxial growth.Atom by the atomic layer of specific configuration in interface can carry out structural adjustment under energy excitation, adjust
Material can integrally embody obvious resistance difference before and after whole, can be used for information Store.And the material outside interface keeps stable
Structure, so that the fusing that is erasable and not needing material of data.The atomic structure adjustment of limited quantity reduces required excite
Energy, so as to reduce energy needed for operation signal.
The content of the invention
A kind of present situation of the present invention for existing conventional phase change memory and superlattices phase transition storage, it is proposed that low-power consumption
The GeTe/Bi of phase transition storage2Te3Superlattice structure storage medium.
How further the power consumption of reduction superlattices phase transition storage is the focal issue in current phase research field.Wherein
A kind of mode be to interface outside material adjustment.Although the material outside interface does not participate in atomic structure adjustment, energy directly
Influence the complexity of the structural adjustment of interface atom.One of influence factor is stress.Due to the lattice of heterogeneous interface
Matching difference, the stress that interface two layers of material is all applied by other side.And study and show that stress is bigger, interface atomic structure is adjusted
Whole easier generation.Most common superlattice structure is Sb in current phase transition storage2Te3/ GeTe superlattice structures, its lattice
It is adapted for 2.45% (Sb2Te3A=4.264 angstroms of lattice constant, a=4.162 angstroms of GeTe lattice constants).There is researcher to lead to
Toning whole timber material finds Sb2Te/GeTe super crystal lattice materials have lower power consumption demand, and its lattice fit is 2.59%
(Sb2A=4.27 angstroms of Te lattice constants, a=4.162 angstroms of GeTe lattice constants).This patent proposes to use Bi2Te3/ GeTe superlattices
Structure is storage medium, and its lattice mismatch is 5.24% (Bi2Te3A=4.38 angstroms of lattice constant, GeTe lattice constants a=4.162
Angstrom).Bi2Te3The application of/GeTe superlattice structures can more effectively reduce phase-change memory device power consumption.
Make Bi2Te3The phase transition storage of/GeTe superlattice structures application embodies low power capabilities, it is necessary to note following
Key point：
1.Bi2Te3The size of/GeTe superlattice structures.
Bi in superlattice structure2Te3It is arranged alternately with GeTe material layers.Bi2Te310-50 angstroms of thickness range of layer.GeTe layers
10-25 angstroms of thickness range.
Bi2Te3Layer is some five layers of atomic structure compositions of Te-Bi-Te-Bi-Te, and this five layers of atoms are an entirety, are
One Bi2Te3Unit, thickness is about 10 angstroms.So Bi2Te3The thickness minimum value of layer is a Bi2Te3The thickness of unit, about
10 angstroms.Adjacent Bi2Te3Combined between unit by van der waals effects (van der Waals interaction).With Bi2Te3
Bi in layer2Te3The increase of unit, interface proportion reduces, and material is closer to body material, and superlattices bring performance advantage to subtract
It is weak.So Bi2Te3Layer should be controlled in five Bi2Te3Below unit, about 50 angstroms.
It is not excluded for that thicker Bi can be used in preparation process2Te3, GeTe or Sb2Te3Deposited etc. material layer as material
Cushion (buffering Bi2Te3Or the lattice mismatch of GeTe materials and substrate).So being included in the artificial storage medium of this patent
One Bi2Te3/ GeTe circulations belong to the Bi of this patent description2Te3/ GeTe superlattice structures, regardless of whether in storage medium
In introduce other thickness either material material.
2.Bi2Te3The preparation of/GeTe superlattice structures.
Bi2Te3The preparation of/GeTe superlattice structures can be by physical vapor deposition, chemical vapor deposition, outside molecular beam
Prolong deposition.By controlling preparation condition, the Bi prepared2Te3Layer is in crystalline state with GeTe layers and interface is clear, element-free phase
Counterdiffusion.
In phase change memory chip fabrication process, in Bi2Te3In every technique after the completion of the preparation of/GeTe superlattice structures,
Low chip should be avoided to apply excessive temperature.Excessive temperature can make the atom inside and outside interface carry out structural adjustment, and interface is caused not
Reversible destruction.It should will apply temperature control below 500 DEG C.
3.Bi2Te3The use of/GeTe superlattice structures.
Based on Bi2Te3The signal of the erasable operation of phase transition storage of/GeTe superlattice structures should be controlled in zone of reasonableness, behaviour
Making the energy of signal offer can adjust interface atomic structure, but too high can not cause atomic structure adjustment at the interface outside, cause pair
Superlattice structure causes irreversible destruction.Concrete signal intensity is different and variant with size according to device architecture.As excellent
Choosing, electric impulse signal voltage range is 0.5~4.0V.
Main beneficial effect of the invention is by design, prepared and test b i2Te3/ GeTe superlattices phase transition storages, card
Advantage of the real power consumption of phase-change memory due to embodying low-power consumption using the superlattice structure that the present invention is mentioned, solves tradition
This excessive bottleneck problem of operation electric current of phase transition storage.
Brief description of the drawings
Fig. 1 Bi2Te3/ GeTe superlattice structure schematic diagrames.It is atomic structure schematic diagram on the left of figure, with four layers of Ge, Te in figure
Atom is one layer of GeTe material layer, with four Bi2Te3Unit is one layer of Bi2Te3Layer (20 layers of atom).Right figure is laminar film knot
Structure, A is GeTe layer thickness, about 10-25 angstroms.C is Bi2Te3Thickness degree, about 10-50 angstroms.A+C is a circulation, entirely
Bi2Te3/ GeTe superlattice structures are circulated comprising multiple A+C.
Fig. 2 Bi2Te3Operating result of/GeTe superlattice structures the device under 20ns voltage pulses.
Embodiment
The present invention is further analyzed with reference to specific embodiment.
1.Bi2Te3/ GeTe superlattice structures prepare specific preparation method
Here Bi is enumerated2Te3The magnetron sputtering physical vapor deposition preparation method of/GeTe superlattice structures.In order to be formed
High-quality epitaxy heterogeneous interface, Bi2Te3Preparation with GeTe layers requires that crystal grain is as big as possible, and perfect state is monocrystalline.But
Under the conditions of magnetron sputtering, due to sputtering the limitation of physical principle, crystal formation is difficult, and we can only adjust preparation parameter preparation
Crystallite dimension big Bi as far as possible2Te3With GeTe layers.According to Bi2Te3With the kinetic character of GeTe Crystallizations, to preparing bar
Temperature is as high as possible when part requirement is prepares, and film preparation speed is as slow as possible.Preparation temperature again can not be too high so that boundary simultaneously
Atom outside face can be carried out structural adjustment, so we obtain suitable film deposition temperature for 300 DEG C by experiment.It is thin
Film preparation speed is 2nm/min.
Design parameter is：The local vacuum 2.1 × 10 of sputtering chamber-4Pascal；Sputtering pressure is 2.1 Pascals；Sputter gas
For Ar；300 DEG C of substrate temperature；Bi2Te3Sputtered using radio-frequency power supply, 15 watts of sputtering power；GeTe is sputtered using radio-frequency power, is splashed
Penetrate 10 watts of power.
2.Bi2Te3The test of/GeTe superlattices phase transition storages
Such as Fig. 1, the Bi of 20 atomic layers2Te3It is super that 10 circulations of GeTe layers alternating deposit of layer and 4 atomic layers are formed
Lattice structure is used as the storage medium of phase transition storage, about 50 nanometers of its thickness.Phase-change memory cell uses 190 nanometer diameter tungsten
The T-type structure of hearth electrode, Top electrode is titanium nitride.Phase transition storage is carried out by applying operation signal between upper/lower electrode
The reading of data is erasable, as a result as shown in Figure 2.
Memory cell low resistance is about 800 ohm, and high resistance is about 50000 ohm.Utilize the voltage pulse pair of 20 nanoseconds
Memory cell is operated, and 0.7 volt can be such that resistive memory cell converts from high to low, realize the erasing of data；2.3 volts
Voltage can be such that resistive memory cell converts from low to high, realize the write-in of data.The reading of data uses 0.1 volt of voltage,
Influence will not be produced on the information state of memory cell.
Above-described embodiment is not the limitation for the present invention, and the present invention is not limited only to above-described embodiment, as long as meeting
Application claims, belong to protection scope of the present invention.
Claims (9)
1. a kind of GeTe/Bi for low power consumption phase changing memory2Te3Superlattice structure storage medium, it is characterised in that comprising extremely
A few Bi2Te3Layer and GeTe material layers stack Bi between unit, adjacent cells2Te3Layer and GeTe material layers are arranged alternately；It is described
Bi2Te3Layer thickness range is 10~50 angstroms, and GeTe layers of thickness range are 10~25 angstroms；
Described Bi2Te3Layer includes some Bi2Te3Unit, wherein Bi2Te3Unit is five layers of atom knots of Te-Bi-Te-Bi-Te
Structure；Adjacent Bi2Te3Acted on and combined by van der waals between unit.
2. GeTe/Bi as claimed in claim 12Te3Superlattice structure storage medium, it is characterised in that Bi2Te3Element thickness is about
For 10 angstroms.
3. GeTe/Bi as claimed in claim 12Te3Superlattice structure storage medium, it is characterised in that also comprising other materials
Material, the cushion deposited as material.
4. GeTe/Bi as claimed in claim 12Te3Superlattice structure storage medium, it is characterised in that also comprising other thickness
Bi2Te3Layer, the cushion deposited as material.
5. GeTe/Bi as claimed in claim 12Te3Superlattice structure storage medium, it is characterised in that Bi2Te3Layer and GeTe layers
Crystalline state is in, and interface is clear, element-free phase counterdiffusion.
6. GeTe/Bi as claimed in claim 12Te3The preparation method of superlattice structure storage medium, it is characterised in that utilize
It is prepared by physical vapor deposition, chemical vapor deposition or molecular beam epitaxy deposition.
7. GeTe/Bi as claimed in claim 62Te3The preparation method of superlattice structure storage medium, it is characterised in that physics
The actual conditions that vapor deposition method is used：
The local vacuum 2.1 × 10 of sputtering chamber-4Pascal；Sputtering pressure is 2.1 Pascals；Sputter gas is Ar；Substrate temperature 300
℃；Bi2Te3Sputtered using radio-frequency power supply, 15 watts of sputtering power；GeTe is sputtered using radio-frequency power, 10 watts of sputtering power.
8. GeTe/Bi as claimed in claim 12Te3The application of superlattice structure storage medium, it is characterised in that be used as phase
When transition storage carries out erasable operation, the energy that operation signal is provided can adjust interface atomic structure, and too high can not cause
Atomic structure is adjusted outside interface, causes to cause superlattice structure irreversible destruction.
9. GeTe/Bi as claimed in claim 82Te3The application of superlattice structure storage medium, it is characterised in that be used as phase
When transition storage carries out erasable operation, electric impulse signal voltage range is 0.5~4.0V.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN109935685A (en) * | 2019-01-31 | 2019-06-25 | 华中科技大学 | A kind of method of controlled material Vacancy defect |
| CN110571235A (en) * | 2019-08-30 | 2019-12-13 | 华中科技大学 | three-dimensional superlattice phase change storage array and preparation method and application thereof |
| CN111952363A (en) * | 2017-11-17 | 2020-11-17 | 华中科技大学 | Superlattice [ GeTe/Sb ] capable of realizing surface state regulation of topological insulator2Te3]n material |
| CN112242487A (en) * | 2020-10-15 | 2021-01-19 | 华中科技大学 | Gate tube with quasi-superlattice structure and preparation method thereof |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN111952363A (en) * | 2017-11-17 | 2020-11-17 | 华中科技大学 | Superlattice [ GeTe/Sb ] capable of realizing surface state regulation of topological insulator2Te3]n material |
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| CN110571235A (en) * | 2019-08-30 | 2019-12-13 | 华中科技大学 | three-dimensional superlattice phase change storage array and preparation method and application thereof |
| CN112242487A (en) * | 2020-10-15 | 2021-01-19 | 华中科技大学 | Gate tube with quasi-superlattice structure and preparation method thereof |
| CN112242487B (en) * | 2020-10-15 | 2022-08-12 | 华中科技大学 | Gate tube with quasi-superlattice structure and preparation method thereof |
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