CN100409379C - Crystal size-controllable polycrystalline Fe3O4 thin-film material and its preparation method - Google Patents

Crystal size-controllable polycrystalline Fe3O4 thin-film material and its preparation method Download PDF

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CN100409379C
CN100409379C CNB2006100130551A CN200610013055A CN100409379C CN 100409379 C CN100409379 C CN 100409379C CN B2006100130551 A CNB2006100130551 A CN B2006100130551A CN 200610013055 A CN200610013055 A CN 200610013055A CN 100409379 C CN100409379 C CN 100409379C
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polycrystalline
preparation
film material
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film
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CN1805080A (en
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刘晖
王健
王雅欣
孙云
张德贤
李养贤
李志青
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Nankai University
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Abstract

The present invention belongs to a polycrystalline Fe3 O4 film material with controllable crystal grain size and a preparation method of the polycrystalline Fe3 O4 film material. A polycrystalline Fe3 O4 film is formed on a basal piece, the diameter of a crystal grain is from 19 to 42 nanometers, and the magnetoelectric numerical value of the film is from 11 to 12% at room temperature. The present invention adopts a dc magnetron sputtering technique, the film is firstly formed by sputtering in the mixed atmosphere of argon gas and oxygen, and then, the polycrystalline Fe3 O4 film material is prepared by the continuous control of annealing temperature and the annealing time. The materials of the basal piece are glass, quartz, single crystal silicon, single crystal gallium arsenide, etc. and the basal piece is not heated at the time of sputtering. Compared with the existing congener materials, the polycrystalline Fe3 O4 film material obtained by the present invention has the advantages of continuous control of crystal grain size, high magnetoelectric numerical value at the room temperature, simple preparation process, adaption to various basal pieces, etc.

Description

The polycrystalline Fe that grain size is controlled 3O 4Thin-film material and preparation method thereof
Technical field
The present invention relates to the controlled polycrystalline Fe of grain size 3O 4Thin-film material and preparation method thereof, it is to have the polycrystalline Fe that the grain size of higher room-temperature magnetoresistance numerical value can continuous control 3O 4Thin-film material and preparation method.
Background technology
Seminar from French scientist A.Fert in 1988 has found giant magnetoresistance (giant magnetoresistance, GMR) since the effect, because giant magnetic resistor material has highfield sensitivity, therefore be widely applied to computer magnetic reading head, Weak magentic-field detection, position probing or the like magneto-dependent sensor spare very soon, relate to ambits such as information technology, medical science, chemistry, biology.Over particularly nearest more than 10 years, the application and development of magnetic resistance material is obtained progress rapidly, receive tangible economic benefit and social benefit.
Giant magnetoresistance effect derives from the electronic transmission process and scattering effect spin correlation or tunneling effect, and it is relevant with the spin polarizability of the relative orientation of the magnetization of adjacent magnet unit and conduction electron.In the giant magnetoresistance effect of MTJ or magnetic metal-insulator particle system, the transport mechanism of electronics is a tunnel effect, this giant magnetoresistance effect be also referred to as usually tunnelling type magneto-resistor (tunnel magnetoresistance, TMR).The magneto-resistance effect of tunnelling type is proportional to the spin polarizability of ferromagnetic material, has high magneto-resistor numerical value.Therefore, seeking and successfully prepare the magnetic material with high spinning polarizability is present this field one of active subject the most.
Fe 3O 4, CrO 2, materials such as LaSrMnO, NiMnSb band structure between metal and insulator, be called as semimetal (half-metal) material.For a spin direction, the band structure of semi-metallic has metallic character, has certain density of states near Fermi surface; And to another kind of spin direction, its band structure has the insulator characteristic, near Fermi surface the density of states be zero or electronics be localization, therefore, semi-metallic should have 100% spin polarizability and the highest magneto-resistor numerical value.
In known semi-metallic, Fe 3O 4The highest high-curie temperature with 850K, in addition, Fe 3O 4Have also that crystal structure is simple, phase structure is stable, still can strictly keep its stoicheiometry and structure than metal material resistance to oxidation, below 10nm, low or the like the advantage of preparation cost, becomes the preferred material of magnetoelectronic devices materials such as magnetic recording magnetic reading head, magnetic random memory.
At present, the Fe of bibliographical information 3O 4The preparation method of film has multiple, can be divided into from preparing on the raw-material type: prepare the iron film earlier, be oxidized to Fe then 3O 4Film; Evaporation or sputter iron material directly prepare Fe under oxygen atmosphere 3O 4Film; With direct evaporation or sputter Fe 3O 4Material forms Fe 3O 4Three classes such as film.On used device type, preparation Fe 3O 4The method of film can be divided into pulsed laser deposition, molecular beam epitaxy, magnetron sputtering, electron beam evaporation or the like, sees Table 1.At above-mentioned preparation Fe 3O 4In the method for film, the employed substrate overwhelming majority is a monocrystal material, and preparation temperature is more than 250 ℃, and complicated process of preparation, the difficult control of condition.And above-mentioned document does not relate to concrete preparation method.
Magneto-resistance effect is a kind of extrinsic performance of material, and its size is closely related with material interface or granule boundary, for example the Fe of block 3O 4The magneto-resistor numerical value of monocrystalline approaches zero.Therefore, for Fe 3O 4Film is used as the material in the magneto-resistance device, must find have high room-temperature magnetoresistance numerical value, preparation technology is simple, grain size can continuous control, be applicable to the polycrystalline Fe of multiple substrate 3O 4The thin-film material preparation methods.
Table 1: the Fe that reports in the document 3O 4Several preparation methods in the film
The preparation method Substrate Growth temperature Raw material The document source
Pulsed laser deposition Monocrystalline MgO (001) or single crystalline Si (001) 340 ℃ Fe 3O 4Target D.Reisinger，P.Majewski，M.Opel，et. al.，Appl.Phys.Lett.85，4980(2004).
Oxonium ion accessory molecule beam epitaxy Monocrystalline MgO (100) 250 ℃ Iron Y.Zhou，X.Jin，and I.V.Shvets，J. Appl.Phys.95，7357(2004).
Dijection frequency power magnetron sputtering Single crystalline Si (100) Room temperature Iron J.P.Hong，S.B.Lee，Y.W.Jung，et. al.，Appl.Phys.Lett.83，1590(2003).
Electron beam evaporation Monocrystalline GaAs (100) Room temperature The oxidation of iron film Y.X.Lu，J.S.Claydon，Y.B.Xu，et. al.，Phys.Rev.B 70，233304-1～4 (2004).
Magnetically controlled DC sputtering Monocrystalline GaAs (100) 400 ℃ Iron S.M.Watts，K.Nakajima，S.van Dijken，et.al.，J.Appl.Phys.95，7465 (2004).
Molecular beam epitaxy Monocrystalline α-Al 2O 3 (0001) 300 ℃ Iron H.Li，Y.Wu，Z.Guo，et.al.，Appl. Phys.Lett.86，252507(2005)
Summary of the invention
The purpose of this invention is to provide the controlled polycrystalline Fe of a kind of grain size 3O 4Thin-film material and preparation method thereof can solve Fe in the prior art 3O 4The problem that exists in thin-film material and the preparation process thereof.The polycrystalline Fe that it is prepared 3O 4Thin-film material has higher room-temperature magnetoresistance numerical value, and the size of crystal grain can continuously change in 19～42nm scope in the film.
The polycrystalline Fe that a kind of grain size provided by the invention is controlled 3O 4Thin-film material is to deposit polycrystalline Fe earlier on substrate 3O 4Film, then by annealing under different temperature and control annealing time preparation, Fe 3O 4Crystal particle scale is 19～42 nanometers, and the thickness of film is about 100～500nm, and the crystal grain random orientation does not have texture, and the room-temperature magnetoresistance numerical value of film is 11～12%; Described substrate is glass, quartz, polyester, monocrystalline silicon or monocrystalline GaAs etc.
The polycrystalline Fe that grain size of the present invention is controlled 3O 4The preparation method of thin-film material comprises the following steps:
1) adopt general superhigh vacuum magnetron sputtering film-plating machine, installation purity is 99.99% iron target on the target platform, and the thickness of target is 2.5mm, and diameter is 60mm;
2) with after substrate cleaning, the oven dry, be installed on the substrate turntable, the distance of substrate and iron target is 8cm;
3) vacuumize, make the back of the body of sputter vacuum chamber at the bottom of vacuum degree be better than 3 * 10 -7Torr;
4) 99.999% highly purified argon gas is fed vacuum chamber, argon flow amount is 10sccm;
5) drop to 3 * 10 in vacuum degree -4During Torr, the open degree of ultra high vacuum slide valve is set at 20%;
6) 99.999% highly purified oxygen is fed vacuum chamber, oxygen flow is 3.8～4.2sccm;
7) treat vacustat after, on the iron target, be set at 150 watts direct current power, pre-sputter 10～15 minutes;
8) open the baffle plate spatter film forming of iron target and substrate, substrate is with 20～25 rev/mins speed Rotating with Uniform, and substrate is not heated.
9) after sputtering sedimentation is finished, continue to keep the argon gas and the oxygen of same traffic under 100～400 ℃ temperature, to anneal half an hour.
10) closure molecule pump and mechanical pump are opened vacuum chamber, take out the prepared film sample.
Described polycrystalline Fe 3O 4The preparation method of thin-film material is to use direct current magnetron sputtering process to prepare in the mixed atmosphere of argon gas and oxygen, and substrate does not heat in the deposition process.
Described polycrystalline Fe 3O 4The preparation method of thin-film material is the preparation of annealing under 100 ℃ to 400 ℃ temperature in the mixed atmosphere of argon gas and oxygen.
Described polycrystalline Fe 3O 4The preparation method of thin-film material, oxygen flow is 4.0sccm in preparation process.
Described polycrystalline Fe 3O 4The used substrate of the preparation method of thin-film material is glass, quartz, monocrystalline silicon or monocrystalline GaAs.
Described polycrystalline Fe 3O 4The application of thin-film material is to can be used to make magneto-dependent sensor spares such as computer magnetic reading head, magnetic random memory, Weak magentic-field detection or position probing.
The polycrystalline Fe that the present invention prepares 3O 4Thin-film material is compared with present same type of material of depositing, and its grain size can continuously change in 19～42nm scope, and have higher room-temperature magnetoresistance numerical value, preparation technology simple, be applicable to advantage such as multiple substrate.
Description of drawings
Fig. 1 is that the thickness of embodiment 1 preparation is the bright field image of transmission electron microscope of the polycrystalline Fe3O4 thin-film material of 310nm.
Fig. 2 is that the thickness of embodiment 1 preparation is the polycrystalline Fe of 310nm 3O 4The room-temperature magnetoresistance test result of thin-film material.
Fig. 3 is the polycrystalline Fe of embodiment 2 preparations 3O 4The bright field image of the transmission electron microscope of thin-film material.
Fig. 4 is the polycrystalline Fe of embodiment 3 preparations 3O 4The bright field image of the transmission electron microscope of thin-film material.
Fig. 5 is the polycrystalline Fe of embodiment 4 preparations 3O 4The bright field image of the transmission electron microscope of thin-film material.
Embodiment
Below will the present invention is further illustrated by specific embodiment.
Polycrystalline Fe 3O 4The magneto-resistance effect of thin-film material is a kind of extrinsic performance of material, and is closely related with factors such as the grain size of material, thickness, intergranular interactions.The present invention utilizes magnetically controlled sputter method, earlier deposition polycrystalline Fe on substrates such as glass, quartz, monocrystalline silicon, monocrystalline GaAs 3O 4Thin-film material then, by annealing under different temperature and control annealing time, obtains the polycrystalline Fe that grain size can continuously change in 19～42nm scope 3O 4Thin-film material.Use glass to be substrate among the embodiment, processing method for substrate is: substrate is placed in the absolute methanol with ultrasonic waves for cleaning three times each three minutes and renew liquid; Use rinsed with deionized water then five times, each three minutes and renew liquid; Compressed nitrogen with drying dries up.
Embodiment 1
1) the DPS-III type superhigh vacuum magnetron sputtering film-plating machine at Shenyang section of employing Chinese Academy of Sciences instrument center, installation purity is 99.99% iron target on the target platform, and the thickness of target is 2.5mm, and diameter is 60mm;
2) with after substrate cleaning, the oven dry, be installed on the substrate turntable, the distance of substrate and iron target is 8cm;
3) vacuumize (promptly less than) 3 * 10 that make that vacuum degree is better than at the bottom of the back of the body of sputter vacuum chamber -7Torr;
4) 99.999% highly purified argon gas is fed vacuum chamber, argon flow amount is 10sccm;
5) drop to 3 * 10 in vacuum degree -4During Torr, the open degree of ultra high vacuum slide valve is set at 20%;
6) 99.999% highly purified oxygen is fed vacuum chamber, oxygen flow is 4.0sccm;
7) treat vacustat after, on the iron target, be set at 150 watts direct current power, pre-sputter 15 minutes;
8) open the baffle plate spatter film forming of iron target and substrate, substrate is with 25 rev/mins speed Rotating with Uniform, and substrate is not heated.
9) after sputtering sedimentation is finished, close the DC power supply of iron target, continue to keep argon gas and oxygen half an hour of same traffic.
10) closure molecule pump and mechanical pump are opened vacuum chamber, take out the prepared film sample.
The employing model is that the transmission electron microscope of JEOL 2010F is the polycrystalline Fe of 310nm to embodiment 1 prepared thickness 3O 4Thin-film material is tested, and its mean particle size is seen Fig. 1 at 19.7nm.
The physical property measuring instrument PPMS-9 that utilizes U.S. Quantum Design company to produce, the thickness of having measured embodiment 1 preparation is the polycrystalline Fe of 310nm 3O 4The room temperature magneto-resistor of thin-film material, institute adds magnetic field and is parallel to film surface, and the magneto-resistor numerical value that records is 12.1% under the magnetic field of 50KOe, the results are shown in Figure 2.
Embodiment 2
1) the DPS-III type superhigh vacuum magnetron sputtering film-plating machine at Shenyang section of employing Chinese Academy of Sciences instrument center is the polycrystalline Fe of 310nm with embodiment 1 prepared thickness 3O 4Thin-film material is placed on the annealing furnace;
2) vacuumize, make the back of the body of sputter vacuum chamber at the bottom of vacuum degree be better than 3 * 10 -7Torr;
3) 99.999% highly purified argon gas is fed vacuum chamber, argon flow amount is 10sccm;
4) drop to 3 * 10 in vacuum degree -4During Torr, the open degree of ultra high vacuum slide valve is set at 20%;
5) 99.999% highly purified oxygen is fed vacuum chamber, oxygen flow is 4.0sccm;
6) under 100 ℃ temperature, anneal half an hour.
7) closure molecule pump and mechanical pump are opened vacuum chamber, take out sample.
The employing model is that the transmission electron microscope of JEOL 2010F is the polycrystalline Fe of 310nm to embodiment 2 prepared thickness 3O 4Thin-film material is tested, and its mean particle size is seen Fig. 3 at 21.0nm.
Embodiment 3
1) the DPS-III type superhigh vacuum magnetron sputtering film-plating machine at Shenyang section of employing Chinese Academy of Sciences instrument center is the polycrystalline Fe of 310nm with embodiment 1 prepared thickness 3O 4Thin-film material is placed on the annealing furnace;
2) vacuumize, make the back of the body of sputter vacuum chamber at the bottom of vacuum degree be better than 3 * 10 -7Torr;
3) 99.999% highly purified argon gas is fed vacuum chamber, argon flow amount is 10sccm;
4) drop to 3 * 10 in vacuum degree -4During Torr, the open degree of ultra high vacuum slide valve is set at 20%;
5) 99.999% highly purified oxygen is fed vacuum chamber, oxygen flow is 4.0sccm;
6) under 200 ℃ temperature, anneal half an hour.
7) closure molecule pump and mechanical pump are opened vacuum chamber, take out sample.
The employing model is that the transmission electron microscope of JEOL 2010F is the polycrystalline Fe of 310nm to embodiment 3 prepared thickness 3O 4Thin-film material is tested, and its mean particle size is seen Fig. 4 at 23.0nm.
Embodiment 4
1) the DPS-III type superhigh vacuum magnetron sputtering film-plating machine at Shenyang section of employing Chinese Academy of Sciences instrument center is the polycrystalline Fe of 310nm with embodiment 1 prepared thickness 3O 4Thin-film material is placed on the annealing furnace;
2) vacuumize, make the back of the body of sputter vacuum chamber at the bottom of vacuum degree less than 3 * 10 -7Torr;
3) 99.999% highly purified argon gas is fed vacuum chamber, argon flow amount is 10sccm;
4) drop to 3 * 10 in vacuum degree -4During Torr, the open degree of ultra high vacuum slide valve is set at 20%;
5) 99.999% highly purified oxygen is fed vacuum chamber, oxygen flow is 4.0sccm;
6) under 400 ℃ temperature, anneal half an hour.
7) closure molecule pump and mechanical pump are opened vacuum chamber, take out sample.
The employing model is that the transmission electron microscope of JEOL 2010F is the polycrystalline Fe of 310nm to embodiment 4 prepared thickness 3O 4Thin-film material is tested, and its mean particle size is seen Fig. 5 at 41.7nm.
The polycrystalline Fe that the present invention prepares3O 4Thin-film material is compared with present same type of material of depositing, and its grain size can continuous control between 20～42 nm, and have higher room-temperature magnetoresistance numerical value, preparation technology simple, be applicable to the advantage such as multiple substrate.

Claims (6)

1. polycrystalline Fe that grain size is controlled 3O 4The preparation method of thin-film material is characterized in that comprising the following steps:
1) adopt general superhigh vacuum magnetron sputtering film-plating machine, installation purity is 99.99% iron target on the target platform, and the thickness of target is 2.5mm, and diameter is 60mm;
2) with after substrate cleaning, the oven dry, be installed on the substrate turntable, the distance of substrate and iron target is 8cm;
3) vacuumize, make the back of the body of sputter vacuum chamber at the bottom of vacuum degree less than 3 * 10 -7Torr;
4) 99.999% highly purified argon gas is fed vacuum chamber, argon flow amount is 10sccm;
5) drop to 3 * 10 in vacuum degree -4During Torr, the open degree of ultra high vacuum slide valve is set at 20%;
6) 99.999% highly purified oxygen is fed vacuum chamber, oxygen flow is 3.8～4.2sccm;
7) treat vacustat after, on the iron target, be set at 150 watts direct current power, pre-sputter 10～15 minutes;
8) open the baffle plate spatter film forming of iron target and substrate, substrate is with 20～25 rev/mins speed Rotating with Uniform, and substrate is not heated;
9) after sputtering sedimentation is finished, continue to keep the argon gas and the oxygen of same traffic under 100～400 ℃ temperature, to anneal half an hour;
10) closure molecule pump and mechanical pump are opened vacuum chamber, take out the prepared film sample.
2. polycrystalline Fe according to claim 1 3O 4The preparation method of thin-film material is characterized in that using direct current magnetron sputtering process to prepare in the mixed atmosphere of argon gas and oxygen, and substrate does not heat in the deposition process.
3. polycrystalline Fe according to claim 1 3O 4The preparation method of thin-film material is characterized in that in the mixed atmosphere of argon gas and oxygen annealing under the temperature of 100 ℃ or 400 ℃.
4. polycrystalline Fe according to claim 1 3O 4The preparation method of thin-film material is characterized in that oxygen flow is 4.0sccm in preparation process.
5. polycrystalline Fe according to claim 1 3O 4The preparation method of thin-film material is characterized in that substrate for use is glass, quartz, monocrystalline silicon or monocrystalline GaAs.
6. the polycrystalline Fe of the described preparation method of claim 1 preparation 3O 4The application of thin-film material is characterized in that being used for making computer magnetic reading head, magnetic random memory, Weak magentic-field detection or position probing magneto-dependent sensor spare.
CNB2006100130551A 2006-01-16 2006-01-16 Crystal size-controllable polycrystalline Fe3O4 thin-film material and its preparation method Expired - Fee Related CN100409379C (en)

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JP4832442B2 (en) * 2006-01-24 2011-12-07 パナソニック株式会社 ELECTRIC ELEMENT AND MEMORY DEVICE
CN101345287B (en) * 2008-09-03 2010-06-02 南开大学 Method for regulating resistivity of polycrystal Fe3O4 thin-film material

Non-Patent Citations (5)

* Cited by examiner, † Cited by third party
Title
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. .;高温退火Fe3O4薄膜的结构和磁输运性质研究. 张国民等.中央民族大学学报（自然科学版），第13卷第2期. 2004 *
退火温度对溅射Al膜微结构及光学常数的影响. 宋学萍等.安徽大学学报（自然科学版），第29卷第3期. 2005
退火温度对溅射Al膜微结构及光学常数的影响. 宋学萍等.安徽大学学报（自然科学版），第29卷第3期. 2005 *
高温退火Fe3O4薄膜的结构和磁输运性质研究. 张国民等.中央民族大学学报（自然科学版），第13卷第2期. 2004

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