Source: http://www.google.com/patents/US8049993?dq=7222078
Timestamp: 2015-08-02 16:33:05
Document Index: 790875394

Matched Legal Cases: ['Application No. 2007', 'Application No. 2009', 'Application No. 10', 'Application No. 2007', 'Application No. 2009', 'Application No. 200810099507']

Patent US8049993 - Magnetic recording medium and magnetic storage device - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inAdvanced Patent SearchPatentsA magnetic recording medium includes: a substrate; a recording layer that is formed on the substrate to have a grooved pattern; and a protection layer formed on the recording layer to fill in the grooved pattern, wherein the recording layer is defined to have a servo portion that retains servo data and...http://www.google.com/patents/US8049993?utm_source=gb-gplus-sharePatent US8049993 - Magnetic recording medium and magnetic storage deviceAdvanced Patent SearchPublication numberUS8049993 B2Publication typeGrantApplication numberUS 12/076,004Publication dateNov 1, 2011Filing dateMar 12, 2008Priority dateMay 14, 2007Fee statusPaidAlso published asCN101308669A, US20080285174Publication number076004, 12076004, US 8049993 B2, US 8049993B2, US-B2-8049993, US8049993 B2, US8049993B2InventorsSatoshi Shirotori, Yoshiyuki Kamata, Kaori KimuraOriginal AssigneeKabushiki Kaisha ToshibaExport CitationBiBTeX, EndNote, RefManPatent Citations (105), Non-Patent Citations (6), Referenced by (4), Classifications (7), Legal Events (2) External Links: USPTO, USPTO Assignment, EspacenetMagnetic recording medium and magnetic storage device
US 8049993 B2Abstract
A magnetic recording medium includes: a substrate; a recording layer that is formed on the substrate to have a grooved pattern; and a protection layer formed on the recording layer to fill in the grooved pattern, wherein the recording layer is defined to have a servo portion that retains servo data and a recording track portion that retains recording data, and wherein a first film thickness of the protection layer at the servo portion is larger than a second film thickness of the protection layer at the recording track portion by a thickness that is in a range from 1 nm to 10 nm.
The present disclosure relates to the subject matters contained in Japanese Patent Application No. 2007-128318 filed on May 14, 2007, which is incorporated herein by reference in its entirety.
The present invention relates to a patterned servo-type magnetic recording medium whose servo portion is patterned in response to whether or not a magnetic substance is provided or grooves are formed and a storage device provided with the magnetic recording medium.
Due to a significant functional improvement of information equipments, such as a personal computer, in recent years, an amount of information handled by a user is enormously increasing. In such circumstances, a storage device having recording density that is tremendously higher than those being conventionally available and a semiconductor device having higher integration degree are required.
According to one aspect of the invention, there is provided a magnetic recording medium including: a substrate; a recording layer that is formed on the substrate to have a grooved pattern; and a protection layer formed on the recording layer to fill in the grooved pattern, wherein the recording layer is defined to have a servo portion that retains servo data and a recording track portion that retains recording data, and wherein a first film thickness of the protection layer at the servo portion is larger than a second film thickness of the protection layer at the recording track portion by a thickness that is in a range from 1 nm to 10 nm.
The protection layer 3 is formed to cover the pattern of the ferromagnetic layer 2. In this case, a thickness of the protection layer 3 on the ferromagnetic layer 2 formed in the servo portion is set larger than a thickness of the protection layer 3 on the ferromagnetic layer 2 formed in the recording track within a range of 1 nm or more but 10 nm or less. In the DTR medium, the rewritable data “1”, “0” must be recorded/played in the recording track portion, and therefore the recording must be executed by the magnetic head. In contrast, the data are patterned based on the presence/absence of the magnetic substance in the servo portion, and therefore there is no need to rewrite the signal after the servo data are written once by applying the DC-transparent magnetic field in one way. The magnetic head can apply only the magnetic field of about 2T due to the material characteristic of a magnetoresistive element. In this case, since the servo portion is patterned depending on the presence/absence of the magnetic substance, the strong magnetic field can be applied in one way, and thus the strong magnetic field can be applied collectively by the magnet, or the like. In other words, the magnetic field applied to the ferromagnetic layer 2 is weakened because of a magnetic spacing, it is difficult to write the servo data unless the magnetic field larger than the magnetic field that the magnetic head can generate normally can be generated. As described above, since the servo portion is patterned depending on the presence/absence of the magnetic substance, the strong magnetic field can be applied in one way and thus the strong magnetic field can be applied all together by the magnet, or the like, so that it is feasible to write the servo signal without the consideration for the load to the magnetic head. As a result, the protection layer 3 in the servo portion can be formed thick.
When the magnetic disk 200 is rotated, a medium opposing surface (ABS: Air Bearing Surface) of the head slider 153 is held at a predetermined floating height from a surface of the magnetic disk 200. In this case, a so-called “contact type”, i.e., the slider contacts the magnetic disk 200 may be used instead of such floating type. The suspension 154 is connected to one end of an actuator arm 155 that is equipped with a bobbin portion to hold a driving coil (not shown), and the like. A voice coil motor 156 as one type of a linear motor is provided to the other end of the actuator arm 155. The voice coil motor 156 is configured by a driving coil (not shown) being wound up in the bobbin portion of the actuator arm 155, and a magnetic circuit including a permanent magnet and an opposing yoke being arranged to oppose with each other while sandwiching the coil therebetween.
As an Example 1, the DTR medium only on the servo portion of which the protection layer was formed thick was manufactured by the above method of manufacturing the magnetic recording medium shown in FIG. 3 to FIG. 8. The protection layer was formed of Ru. The film formation of a 50 nm thickness by the sputtering method and the etching back of 30 nm thickness are repeated five times respectively, and finally a surface of the recording track was planarized by executing the etching back of 100 nm thickness. At this time, when Rmax of a 5 μm square was measured by using the atomic force microscope (AFM), it was confirmed that the track portion was 3 nm and the servo portion was 7 nm and therefore the protection layer overlying the recording layer in the servo portion was thicker than that in the track portion by 4 nm in terms of Rmax (see Table 1).
As an Example 2, the DTR medium only on the servo portion of which the protection layer is thick was formed by the method shown in FIG. 3 to FIG. 8, and NiNbTiHf was used as the protection layer (Table 1). The film formation of a 50 nm thickness by the sputtering method and the etching back of 30 nm thickness are repeated five times respectively, and finally a surface of the recording track was planarized by executing the etching back of 100 nm thickness. At this time, when Rmax of the 5 μm square was measured by using the atomic force microscope (AFM), it was confirmed that the track portion was 3 nm and the servo portion was 6 nm and therefore the protection layer overlying the recording layer in the servo portion was thicker than that in the track portion by 3 nm in terms of Rmax. When Ra of a 100 nm square overlying the recording layer was measure by the AFM, it was confirmed that the surface flatness is excellent like 0.3 nm. After the filling process, the DLC was formed by the CVD method, and the lubricant was coated as the protection layer. When this medium was measured in the atmospheric pressurization by the digital Laser Doppler Vibration meter (LDV), the resonance caused due to the unevenness of the servo portion was not found. Also, when the floating evaluation was made by the glide height tester using the magnetic head having a floating height of 15 nm, the crash due to the unevenness of the protection layer was not found. When the DC demagnetization was executed by the magnet using the spin stand and the drive durability test was executed by installing the head into the drive, the BER of −6.0-th power was obtained.
As an Example 3, the DTR medium only on the servo portion of which the protection layer is thick by 10 nm was formed by the method shown in FIG. 2 to FIG. 8. Ru was used as the protection layer (Table 1). In order to get a difference in film thickness between the protection layer overlying the recording layer and the protection layer overlying the non-recording layer, the film formation of a 50 nm thickness by the sputtering method and the etching back of 30 nm thickness are repeated three times respectively. Thus, a difference of 10 nm of Rmax between the recording track layer and the servo portion was obtained. Finally a surface on the recording track was planarized by executing the etching back of 100 nm thickness. After the filling process, the DLC was formed by the CVD method, and the lubricant was coated as the protection layer. When the DC demagnetization was executed by the magnet using the spin stand and the drive durability test was executed by installing the head into the drive, the BERs of −5.0-th power and −4.0-th power were obtained from the media using Ru and SiO2 as the protection layer respectively.
Except the filling/planarization were executed by the bias sputtering method to align the unevenness in the track portion and the servo portion, the DTR medium whose protection layer is thin in both the track portion and the servo portion was formed by the same method as Example 1. SiO2 was used as the protection layer and Rmax after the planarization by the filling was 4 nm in both the track portion and the servo portion (Table 1).
Except the CVD protection layer after the filling was thick by 10 nm, the DTR medium whose protection layer is thick in both the track portion and the servo portion was formed by the same method as that in Comparative Example 1.
The DTR medium only on the servo portion of which the protection layer is thick by 20 nm was formed by the method shown in FIG. 2 to FIG. 8. SiO2 was used as the protection layer. In order to obtain a difference in film thickness between the protection layer overlying the recording layer and the protection layer overlying the non-recording layer, the film formation of a 50 nm thickness by the sputtering method and the etching back of 30 nm thickness are executed once respectively. Thus, a difference of unevenness of 20 nm was obtained (Table 1). The corrosion test in the high-temperature and high-humidity circumstance, the floating stability evaluation using the AE sensor, and the signal strength comparison in the servo portion by the spin stand were applied to the resultant medium (Table 3).
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English-language translation thereof.6Office Action in Chinese Patent Application No. 200810099507.1, dated Nov. 27, 2009, and English-language translation.Referenced byCiting PatentFiling datePublication dateApplicantTitleUS8760980 *Feb 26, 2013Jun 24, 2014Seagate Technology LlcProtective overcoat layer of carbon and a selected transition metalUS8946835 *Sep 14, 2012Feb 3, 2015Seagate Technology LlcMagnetic device with different planarization areasUS20130017413 *Sep 14, 2012Jan 17, 2013Seagate Technology LlcDiscrete Track MediaUS20130070370 *Sep 14, 2012Mar 21, 2013Seagate Technology LlcPlanarization Method for Media* Cited by examinerClassifications U.S. Classification360/135International ClassificationG11B5/82, G11B5/72Cooperative ClassificationG11B5/72, G11B5/855European ClassificationG11B5/855, G11B5/72Legal EventsDateCodeEventDescriptionApr 16, 2008ASAssignmentOwner name: KABUSHIKI KAISHA TOSHIBA, JAPANFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:SHIROTORI, SATOSHI;KAMATA, YOSHIYUKI;KIMURA, KAORI;REEL/FRAME:020833/0725Effective date: 20080410Apr 15, 2015FPAYFee paymentYear of fee payment: 4RotateOriginal ImageGoogle Home - Sitemap - USPTO Bulk Downloads - Privacy Policy - Terms of Service - About Google Patents - Send FeedbackData provided by IFI CLAIMS Patent Services