CN1305033C - Non-crystal vertical magnetic film for high density vertical magnetic record - Google Patents
Non-crystal vertical magnetic film for high density vertical magnetic record Download PDFInfo
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- CN1305033C CN1305033C CNB021387273A CN02138727A CN1305033C CN 1305033 C CN1305033 C CN 1305033C CN B021387273 A CNB021387273 A CN B021387273A CN 02138727 A CN02138727 A CN 02138727A CN 1305033 C CN1305033 C CN 1305033C
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Abstract
The present invention relates to an amorphous perpendicular magnetization film which can be used for high density perpendicular magnetic recording. The present invention comprises a bottom layer and a magnetic layer, wherein the magnetic layer contains 7% to 18% of light rare earth elements, 19% to 28% of heavy rare earth elements, and 53% to 74% of transitional metal; the material of the bottom layer is Cr, Ti, Mo, or W; a top layer for preventing the magnetic layer from being oxidized can be arranged on the magnetic layer, and the material of the top layer is SiO2, SiN, AlNSi or AlN. When an X-ray diffraction measuring apparatus is adopted to analyze the structure of a sample of the SiO2/SmTbCo/Cr/glass sub perpendicular magnetization film, crystal phases of the rare earth elements and the transitional elements (SmTbCo) are not discovered, which shows that the film is an amorphous film. Through the detection and the analysis of the magnetic performance, the magneto-optical characteristics, the magnetic anisotropy constants and the constituents of the sample, the film has high magnetic anisotropy; a Ku value is higher than 4.5 times 10 <6> erg/cm<3>, and thus, the film has good heat stability. Because the film has a large hysteresis loop rectangular degree and is an amorphous film, the present invention has low thermal noise.
Description
Technical field
The invention belongs to the storage medium technical field, be specifically related to a kind of amorphous perpendicular magnetization film that can be used for high-density perpendicular magnetic recording.
Background technology
In more than ten years in the past, magnetic recording density is always in quick growth.This will give the credit to the development of head technology and coding techniques, the main research and development that then will give the credit to magnetic recording media on the one hand.
Is parallel or vertical according to the magnetization vector of representing tracer signal in the disk with magnetic head direction of motion and card surface, it can be divided into vertically or perpendicular recording.At present, Chang Yong hard disk return to zero still is the longitudinal recording mode.But along with the not only raising of recording density, the thermonoise that is caused by demagnetizing field in the longitudinal recording medium is increasing.And perpendicular magnetic recording, high more its demagnetizing field of recording density is more little on the contrary, and media noise also can correspondingly reduce.In addition, along with improving constantly of magnetic recording surface density, the dimension of recorded bit is also more and more littler thereupon, progressively becomes in the super paramagnetic limit.Therefore, when traditional longitudinal magnetic recording mode was subjected to more and more problems puzzlement, people were stepping up to have the research of perpendicular magnetic recording medium of potentiality of developing on a large scale very much again.
Because the development and the practicability of large reluctance magnetic head (GMR), it is applied to perpendicular magnetic recording, solved the key issue of magnetic head aspect in the perpendicular magnetic recording, thereby make perpendicular magnetic recording become the research hot topic of current high density magnetic recording, so again perpendicular magnetic recording medium is had higher requirement.For perpendicular magnetic recording medium, the present thermonoise that focuses on how reducing medium of research, and the thermal stability of amplified medium how.In order to reduce the thermonoise of medium,, often adopt the way that reduces crystal grain and intercrystalline coupling for the polycrystalline magnetic recording media.In order to reduce intercrystalline interaction, people just attempting to make the sort of with the non magnetic material be template, magnetic-particle is distributed in magnetic recording media wherein.Observe and can find with high resolution electron microscopy, nano-magnetic crystal grain is distributed in wherein in the amorphous film that the employing sputtering method is made.Therefore, adopt the thermonoise of the amorphous magnetic film that sputtering method makes can be very low.In addition, theoretical and experiment shows that all high more its thermonoise of vertical magnetized film of magnetic hysteresis loop rectangle degree is low more.
For the thermal stability of magnetic recording media, can adopt recorded bit magnetic storage can with thermal perturbation can ratio---K
uV*/k
BT weighs, and it is generally acknowledged that this ratio should be 50 to 70.Here, K
uRepresent the magnetic anisotropy constant of medium, V* represents the magnetic switch volume of recorded bit, k
BBe the Boltzman constant, the T representation temperature.Along with the not only raising of record surface density, V* only can be more and more littler, and the thermal stability of medium also can be worse and worse.Improve the thermal stability of medium, adopt K
uThe magnetic recording material that value is bigger is to select preferably
With regard to current research gets more CoCr alloy series film, its polycrystalline structure of forming by the hexagonal cylindrulite from a structural point.In order to reduce crystal grain and intercrystalline coupling, people manage to add elements such as Pt or Ta to strengthen the segregation of Cr at the crystal boundary place, to reduce the thermonoise of deielectric-coating in the CoCr film.In order to make the crystal grain in the CoCr alloy vertical magnetized film that good magnetic hysteresis loop rectangle degree can be arranged, also need under the CoCr alloy-layer, add suitable bottom or cushion, people such as M.Futamoto are once with the bottom of metal Ti as the CoCr alloy film, (see M.Futamoto, Y.Honda, Y.Matsuda in the hope of promoting the magnetospheric columnar growth of CoCr, N.Inab, Technical Report of IEICEMR91-46,1991, p.29).However, it is thick that CoCr alloy vertical magnetized film still exists crystal grain, the shortcoming that magnetic anisotropy can be lower.
Except CoCr alloy series film, Co/Pd, Co/Pt, Fe/Pt metallized multilayer film, barium ferrite vertical magnetized film and the Sm-Co amorphous perpendicular magnetization film of studying morely at present in addition.Though metallized multilayer films such as Co/Pd have magnetic characteristic preferably, but because it is the perpendicular magnetic anisotropic that the interface by multilayer film generates, must make each layer do very thinly, film layer structure is similar to superlattice, so the manufacturing process complexity, manufacturing cost is higher.Though the barium ferrite vertical magnetized film adopts general sputtering method just can obtain, but in order to make film crystallization well, post anneal is necessary, and the sputtering technology condition is too big to the influence of the magnetic property of film in the film-forming process, makes its magnetic characteristic be not easy to control.
Because hard disk magnetic medium---the K of transition metal alloy film CoCrPtTa of common usefulness
uBe worth lowlyer, generally have only 0.2 * 10
7Erg/cm
3And rare earth---transition metal films has bigger K
uValue, SmCo in theory
5The K of crystal grain
uValue can be up to 11-20 * 10
7Erg/cm
3Therefore, if can make the SmCo vertical magnetized film, then its thermal stability will inevitably be very high.But, because light rare earth element has higher saturation magnetization Ms, making at light rare earth---(it is very difficult that the field of LRE-TM) prepares amorphous perpendicular magnetization film for transition metal.Nineteen eighty-three, Li Zuoyi etc. once utilized the radio-frequency sputtering technology to prepare amorphous SmCo vertical magnetized film (to see Lee Z Y first, Numata T, Sakurai Y, " Sm-Co AmorphousFilm with Perpendicular Anisotropy ", Jpn J Appl Phys, 1983,22 (9): L600), and when pointing out that content as Sm is at 18%-20%, the magnetic anisotropy constant K in the Sm-Co amorphous perpendicular magnetization film
uMaximum.Because this film is amorphous film, the exchange interaction of superfine crystal grain and intergranule is very little in the film.Therefore, its thermonoise can be very little.But because its saturation magnetization M
sWith coercive force H
cValue be not too big, limited their extensive uses aspect perpendicular magnetic recording.
By contrast, preparation heavy rare earth---transition metal (HRE-TM) the amorphous perpendicular magnetization film ratio is easier to realize, but because the saturation magnetization M of this film
sVery little and coercive force H
cBut very high, make magnetic head all become very difficult aspect the signal counter-rotating obtaining signal and make, therefore, the also not too suitable perpendicular magnetic recording film of doing of this class film.
In sum, if can prepare coercive force H
cWith saturation magnetization M
sSize to fit, magnetic anisotropy constant K
uAnd all higher amorphous perpendicular magnetization film of magnetic hysteresis loop rectangle degree, then can satisfy the requirement of desired low thermonoise of perpendicular magnetic recording medium and high thermal stability.
Summary of the invention
The object of the present invention is to provide a kind of amorphous perpendicular magnetization film that can be used for high-density perpendicular magnetic recording, the coercive force H of this magnetized film
cWith saturation magnetization M
sSize to fit, magnetic anisotropy constant K
uAnd magnetic hysteresis loop rectangle degree is all higher, can satisfy the required low thermonoise of perpendicular magnetic recording medium and the requirement of high thermal stability.
For achieving the above object, a kind of amorphous perpendicular magnetization film that can be used for high-density perpendicular magnetic recording provided by the invention, comprise bottom and magnetosphere, it is characterized in that: described primer is Cr, Ti, Mo, W or Cr alloy, described magnetospheric composition and element ratio are: the light rare earth element of 7.28%-17.85%, the heavy rare earth element of 18.15%-28.72%, the transition metal of 54%-69%; Wherein, light rare earth element is Sm, Nd or Pr element, and heavy rare earth element is Gd, Tb or Dy element, and transition metal is Co or Fe.
According to technique scheme, we have prepared vertical magnetized film.With SiO
2/ SmTbCo/Cr/glasssub vertical magnetized film is an example, when adopting the X-ray diffraction measurement mechanism to analyze these structures of samples, does not find the crystallization phase of rare earth and transition element (SmTbCo), shows that such film is an amorphous film.And adopt vibrations sample magnetometers (VSM) to measure the magnetic property of sample, adopt magneto-optic Kerr effect hysteresiscope to measure the magneto-optical property of sample, adopt automatic magnetic torque instrument to measure the magnetic anisotropy constant of sample, the component of sample that (EDXS) methods analyst has been analyzed in the chromatic dispersion of employing scanning electron microscope X-ray energy spectrum.The magnetic parameter that now provides sample segment with and results of performance analysis such as table 1:
Table 1: the magnetic characteristic that can be used as the sample segment of perpendicular magnetic recording
| Sample film layer structure and component | Rectify object for appreciation power Hc (Oe) | Saturation magnetization Ms (emu/cm 3) | Magnetic hysteresis loop rectangle degree Mr/Ms | Magnetic anisotropy constant Ku (erg/cm 3) |
| SiO 2/Sm 8.86Tb 22.14Co 69/Cr | 3.784×10 3 | 3.41×10 2 | 0.92 | 4.71×10 6 |
| SiO 2/Sm 9.25Tb 21.75Co 69/Cr | 2.558×10 3 | 3.65×10 2 | 0.97 | 4.54×10 6 |
| SiO 2/Sm 17.32Tb 19.68Co 63/Cr | 2.120×10 3 | 3.78×10 2 | 0.96 | 5.32×10 6 |
This as shown in Table 1 film has higher magnetic anisotropy, and the Ku value is higher than 4.5 * 10
6Erg/cm
3Therefore, the good thermal stability that has of this film.And because it has bigger magnetic hysteresis loop rectangle degree, be again amorphous film, its thermonoise will be very low.
Description of drawings
Fig. 1 is the process chart of the inventive method;
Fig. 2 is SiO
2/ Sm
8.86Tb
22.14Co
69(120nm)/Cr (240nm) //glass sub. amorphous magnetized film is perpendicular to the magnetic hysteresis loop of magnetic direction;
Fig. 3 is SiO
2/ Sm
8.86Tb
22.14Co
69(120nm)/Cr (240nm) //the magnetic torque curve of glass sub. amorphous perpendicular magnetization film.
Embodiment
The preparation method of amorphous perpendicular magnetization film provided by the present invention is a magnetron sputtering method, and its technological process as shown in Figure 1.Following embodiment is further described below the present invention.
Embodiment 1:
(1) carries out careful cleaning for substrate, with the greasy dirt of removing substrate surface with attached to other foreign ion on its surface.
(2) adopt the high frequency magnetron sputtering to prepare film.At first install bottom target (as the Cr target), top layer target (as SiO
2) and composition target (or alloys target).Adjust the component of composition target or alloys target, make that the component of target is Sm:7% at atomic ratio---18%, Tb:19%---29%, Co:53%---between 74%.
(3) the base vacuum degree in sputtering system is better than 10
-7Behind the Torr, import sputter gas Ar, make the interior operating air pressure of sputter cavity, respectively target and substrate are carried out several minutes pre-sputter, with cleaning target and substrate surface at 4mT.In sputter procedure, adopt the substrate water-cooled.
(4) because sputtering pressure has certain influence to the surface topography and the grain size of bottom, it is necessary therefore selecting suitable sputtering pressure.Can select suitable sputtering pressure, sputtering power and sputtering time, certain thickness bottom in the first sputter.For example: at the bottom sputtering pressure is 5mT, and sputtering power is 250W, and sputtering time is under the situation of 6min, and thickness is approximately the Cr bottom of 200nm in the sputter.
(5) because the sputtering power size has certain influence for magnetospheric component, and sputtering pressure and sputtering time also can have certain influence to magnetospheric magnetic property.Therefore need to select suitable sputtering pressure, sputtering power and sputtering time, certain thickness magnetosphere in the sputter.For example: can be 3mT at sputtering pressure, sputtering power be 350W, and sputtering time is under the situation of 3min, and thickness is the Sm of 120nm in the sputter
7.15Tb
18.85Co
74Amorphous magnetic layer.
(6) sputter top layer.Certain thickness top layer in the sputter is in order to prevent magnetospheric oxidation.For as the sample of perpendicular magnetic recording, can sputter on certain thickness Cr or SiO
2Layer.For example: can be 2mT at sputtering pressure, sputtering power be that 300W, sputtering time are under the situation of 6min, certain thickness SiO in the sputter
2Layer.
According to embodiment 1, can prepare the sample of other different component, below enumerate the preparation scheme of several different component samples:
Embodiment 2:
| Film layer structure | The rete component | Sputtering power (W) | Sputtering pressure (mTorr) | Sputtering time (min) |
| Top layer magnetosphere bottom | SiO2 Sm 8.86Tb 22.14Co 69Cr | 300 350 250 | 4 4 4 | 3 4 6 |
Embodiment 3:
| Film layer structure | The rete component | Sputtering power (W) | Sputtering pressure (mTorr) | Sputtering time (min) |
| Top layer magnetosphere bottom | SiO 2 Sm 17.85Tb 18.15Co 64 Cr | 300 375 300 | 3 4 5 | 3 3 4 |
Embodiment 4:
| Film layer structure | The rete component | Sputtering power (W) | Sputtering pressure (mTorr) | Sputtering time (min) |
| Top layer magnetosphere bottom | AlN Sm 7.28Tb 28.72Co 64 Cr | 350 400 300 | 4 3 2 | 4 5 4 |
Embodiment 5:
| Film layer structure | The rete component | Sputtering power (W) | Sputtering pressure (mTorr) | Sputtering time (min) |
| Top layer magnetosphere bottom | SiO2 Sm 9.25Tb 21.75Co 69 Cr | 250 275 325 | 2 3 5 | 6 5 3 |
Embodiment 6:
| Film layer structure | The rete component | Sputtering power (W) | Sputtering pressure (mTorr) | Sputtering time (min) |
| Top layer magnetosphere bottom | SiAlN Sm 17.32Tb 27.68Co 54 Ti | 350 400 200 | 4 3 5 | 4 5 6 |
Embodiment 7:
| Film layer structure | The rete component | Sputtering power (W) | Sputtering pressure (mTorr) | Sputtering time (min) |
| Top layer magnetosphere bottom | AlN Nd 14.28Gd 19.72Co 66 W | 300 450 280 | 2 3 4 | 3 5 4 |
Embodiment 8:
| Film layer structure | The rete component | Sputtering power (W) | Sputtering pressure (mTorr) | Sputtering time (min) |
| Top layer magnetosphere bottom | SiAlN Pr 9.67Dy 21.33Fe 69 Cr 85Mo 15 | 285 320 250 | 6 3 4 | 5 5 5 |
Embodiment 9:
| Film layer structure | The rete component | Sputtering power (W) | Sputtering pressure (mTorr) | Sputtering time (min) |
| Top layer magnetosphere bottom | SiN Sm 13.25Gd 23.75Co 63Mo | 350 320 325 | 2 4 5 | 6 4 3 |
Embodiment 10:
| Film layer structure | The rete component | Sputtering power (W) | Sputtering pressure (mTorr) | Sputtering time (min) |
| Top layer magnetosphere bottom | SiO2 Nd 15.74Dy 25.26Fe 59Cr 80V 20 | 300 275 300 | 5 4 6 | 4 6 3 |
According to above-mentioned concrete implementing method, we have prepared SiO
2/ Sm
8.86Tb
22.14Co
69(120nm)/Cr (240nm) //glass sub. amorphous perpendicular magnetization film, and adopt vibrations sample magnetometers (VSM) to measure the magnetic property of sample, adopt automatic magnetic torque instrument to obtain the magnetic torque curve of sample.Fig. 1 and Fig. 2 are respectively the prepared samples vertical of embodiment 1 in the magnetic hysteresis loop and the magnetic torque curve of magnetic direction.
Because the saturation magnetization Ms of heavy rare earth element is less, adopt the sputtering method ratio to be easier to prepare heavy rare earth transition metal (HRE-TM) amorphous perpendicular magnetization film.The magnetic anisotropy constant Ku and the coercivity H of this film are all bigger.But because this film belongs to ferrous magnetic structure, the magnetic moment direction of heavy rare earth element (HRE) is opposite with the magnetic moment direction of transition metal (TM) in the film, causes the saturation magnetization of this film less.And the Ms of light rare earth element is bigger, adopts the sputtering method ratio to be easier to prepare light rare earth transition metal (LRE-TM) face inner membrance, and is not easy to form vertical magnetized film.This film is generally ferromagnetic structure, and the magnetic moment direction of light rare earth element (LRE) is identical with the magnetic moment direction of transition metal (TM) in the film, causes the saturation magnetization of this film higher.Therefore, if a part of heavy rare earth element (HRE) that will form in the amorphous perpendicular magnetization film is replaced by light rare earth element (LRE), the size that can remove the saturation magnetization Ms and the magnetic hysteresis loop rectangle degree of film with (LRE) then.Therefore, in the process of this film of preparation, regulate the ratio (LRE/HRE) of weight rare earth element and the ratio (RE/TR) of rare earth element (RE) and transition metal (TM), can obtain to rectify object for appreciation power and saturation magnetization size to fit, magnetic anisotropy constant and the higher amorphous perpendicular magnetization film of magnetic hysteresis loop rectangle degree, to satisfy the requirement that the perpendicular magnetic recording medium needs reduce thermonoise, increase thermal stability.
For obtained performance amorphous magnetized film preferably, the used substrate of system film must be through strict chemistry and ultrasonic cleaning, and sputtering system also must have higher base vacuum degree, and general base vacuum degree should be better than 10
-7Torr.For the amorphous perpendicular magnetization film that perpendicular magnetic recording is used, bottom can be Cr, Ti, Mo, W or Cr alloy rete.In the process of sputter bottom, the sputtering pressure size can influence the structure and properties of film, therefore, must select suitable sputtering pressure.Oxidized in order to prevent thin magnetic film, must the certain thickness SiO of sputter
2, SiN, AlNSi or AlN layer make protective seam.
Magnetospheric component, thickness and sputtering pressure all can influence its magnetic property.The control of magnetic layer thickness can realize by the control of sputtering time.But the regulation and control of its component are to realize by the component of adjusting composition target or alloys target.The regulation and control of composition target component can ratio (as the number of Sm, Tb sheet) light on Co (or Fe) target by adjusting, heavy rare earth element, and the ratio of rare earth element and transition metal (as the ratio of the content and the Co element of SmTb integral body) realizes.In addition, because the sputter rate of different elements also has difference under identical sputtering power, so the sputtering power size also can influence magnetospheric component.
Select suitable sputtering power, sputtering pressure and sputtering time, adjust the component of target, make the magnetic property of amorphous magnetic layer be: saturation magnetization Ms＞300emu/cm
3, coercivity H between 20000e to 4000Oe, rectangle degree S＞0.9 of magnetic hysteresis loop.The amorphous film that possesses this character can be used as perpendicular magnetic recording medium.
From the known technology of the foregoing description and this area, those of ordinary skills can learn: the light rare earth element among the present invention in the magnetosphere (LRE), heavy rare earth (HRE) element and transition metal (TM) can be wherein any one.But light rare earth element (LRE) is that Sm, Nd, Pr element, heavy rare earth element (HRE) are for Gd, Tb, Dy element, technique effect was better when transition metal (TR) element was Co or Fe.We can also learn from the foregoing description, and the element ratio of light rare earth element is 7%---18%; The element ratio of heavy rare earth element is 19%---28%; The element ratio of transition metal is 53%---74%; Bottom also can be referred to as cushion, all can make primer as Cr, Ti, Mo, W or Cr alloy etc.; Quilting material can be SiO
2, SiN, AlNSi or AlN.
Claims (1)
1. amorphous perpendicular magnetization film that can be used for high-density perpendicular magnetic recording, comprise bottom and magnetosphere, it is characterized in that: described primer is Cr, Ti, Mo, W or Cr alloy, described magnetospheric composition and element ratio are: the light rare earth element of 7.28%-17.85%, the heavy rare earth element of 18.15%-28.72%, the transition metal of 54%-69%; Wherein, light rare earth element is Sm, Nd or Pr element, and heavy rare earth element is Gd, Tb or Dy element, and transition metal is Co or Fe.
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|---|---|---|---|
| CNB021387273A CN1305033C (en) | 2002-06-30 | 2002-06-30 | Non-crystal vertical magnetic film for high density vertical magnetic record |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB021387273A CN1305033C (en) | 2002-06-30 | 2002-06-30 | Non-crystal vertical magnetic film for high density vertical magnetic record |
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| Publication Number | Publication Date |
|---|---|
| CN1392535A CN1392535A (en) | 2003-01-22 |
| CN1305033C true CN1305033C (en) | 2007-03-14 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10177197B2 (en) | 2015-11-16 | 2019-01-08 | Samsung Electronics Co., Ltd. | Magnetic junctions having elongated free layers |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7758982B2 (en) * | 2005-09-02 | 2010-07-20 | Hitachi Global Storage Technologies Netherlands B.V. | SiN overcoat for perpendicular magnetic recording media |
| CN104900242B (en) * | 2015-06-19 | 2017-12-19 | 中国科学院半导体研究所 | A kind of preparation method of the Relation of Ferromagnetic Granular Films with perpendicular magnetic anisotropic |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS63269348A (en) * | 1987-04-27 | 1988-11-07 | Oki Electric Ind Co Ltd | Magneto-optical recording medium |
| JPS6467741A (en) * | 1987-09-09 | 1989-03-14 | Seiko Epson Corp | Manufacture of magneto-optical recording medium |
| US5667887A (en) * | 1989-03-28 | 1997-09-16 | Seiko Epson Corporation | Magneto-optical media |
-
2002
- 2002-06-30 CN CNB021387273A patent/CN1305033C/en not_active Expired - Fee Related
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS63269348A (en) * | 1987-04-27 | 1988-11-07 | Oki Electric Ind Co Ltd | Magneto-optical recording medium |
| JPS6467741A (en) * | 1987-09-09 | 1989-03-14 | Seiko Epson Corp | Manufacture of magneto-optical recording medium |
| US5667887A (en) * | 1989-03-28 | 1997-09-16 | Seiko Epson Corporation | Magneto-optical media |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10177197B2 (en) | 2015-11-16 | 2019-01-08 | Samsung Electronics Co., Ltd. | Magnetic junctions having elongated free layers |
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