KR101622568B1 - Patterning of magnetic thin film using energized ions - Google Patents

Abstract

A method for patterning a magnetic thin film on a substrate includes providing a pattern for the magnetic thin film, wherein selective areas of the pattern allow penetration of activated ions of one or more elements. Active ions having sufficient energy to penetrate selective regions and portions of the magnetic thin film adjacent to the selective regions are generated. The substrate is arranged to receive the activated ions. The portion of the magnetic thin film may be subjected to thermal excitation. The portions of the magnetic thin film are provided to exhibit different magnetic properties from other optional portions. A method for patterning magnetic media with magnetic thin films on both sides of the medium is also disclosed.

Description

BACKGROUND OF THE INVENTION Field of the Invention [0001] The present invention relates to patterning of magnetic thin films using activated ions,

BACKGROUND OF THE INVENTION Field of the Invention The present invention generally relates to patterning of magnetic thin films, and more particularly, to a method of patterning magnetic thin films of magnetic recording media using activated ions.

There is always a need for higher density information storage media for computers. At present, a common storage medium is a hard disk drive (HDD). HDD is a non-volatile storage device that stores digitally encoded data on fast spinning disks with magnetic surfaces. The discs are circular with a central hole. Discs are made of non-magnetic material, typically glass or aluminum, and coated on one or both sides with magnetic films such as cobalt-based alloy thin films. HDDs record data by magnetizing regions of a magnetic film in one of two specific directions to enable binary data storage in the film. The stored data is read by detecting the orientation of the magnetized areas of the film.

A typical HDD design consists of a spindle holding one or more disks spaced apart enough to allow read-write heads to access one or both sides of one or more disks. The disks are secured to the spindle by clamps which are inserted into the central holes in the disks. The disks rotate at a very high speed. The information is written onto and read from the disk as the disk rotates past the read-write heads. The heads move very close to the surface of the magnetic thin film. The read-write head is used to detect and / or modify the magnetization of the material immediately below the read-write head. There is one head for each magnetic disk surface on the spindle. The arm moves the heads across the spindle disks, allowing each head to access almost the entire surface of the corresponding disk.

In conventional magnetic media, each bit cell includes a plurality of randomly dispersed magnetic grains. Ideally, the plurality of magnetic grains are physically separated from each other to provide improved write-ability, signal-to-noise ratio (SNR), and thermal stability.

As the aerial density of the magnetic recording medium increases, the number of bit cells per square inch increases. This reduces the size of the bit cell. In order to efficiently measure transitions, the minimum number of magnetic grains is required in the bit cell. As the bit cell size decreases, the magnetic grain size must correspondingly be reduced to provide the minimum number of magnetic grains in the bit cell. If the isolation in magnetic grains and the reduction in magnetic grain size are improved to insure low noise, the recording density will be limited due to thermal disturbances.

In order to improve the recording density, it is desirable to reduce the recording cell size on the medium, which leads to a decrease in the signal magnetic field intensity generated from the medium. In order to satisfy the SNR required for the recording system, the noise must be reduced corresponding to the decrease in signal strength. Medium noise is mainly caused by fluctuations of magnetization transitions, which are proportional to the magnitude of the magnetization reversal unit made of magnetic grains. Thus, in order to reduce media noise, it is required to isolate magnetic grains by interfering with the exchange interaction between the magnetic grains.

The magnetic energy of an isolated magnetic grain is given by the product of the volume of grain and the anisotropy energy density. It is desirable to reduce the thickness of the medium to reduce the magnetization transition width. It is also desirable to reduce the grain size to meet the requirements for low noise. The reduced magnetic grain size significantly lowers the volume of the magnetic grain and also significantly reduces the magnetic energy of the grain. If the magnetic energy of a given magnetic grain in a magnetic medium is several hundreds times the thermal energy at the operating temperature (e.g., room temperature), the resistance to thermal disturbance is considered sufficient. However, when the magnetic energy of magnetic grains is less than several hundreds of thermal energies, there is a possibility that the magnetization direction of the magnetic grains can be reversed by thermal disturbance, leading to the loss of potentially recorded information.

Various alternatives have been proposed to overcome the problems of thermal disturbances. One alternative is to use magnetic materials with high magnetic anisotropy. These magnetic materials require a higher recording saturated magnetic field from the head to record the magnetic media. Another alternative is to use heat-assisted recording, where a highly anisotropic magnetic material is used and the recording portion is heated by light radiation during recording. The heat lowers the anisotropy of the magnetic grains and the recording saturated magnetic field. This permits recording of magnetic media using a conventional magnetic head.

As the public density increases, there is still a minimum number of magnetic grains still required per bit cell and there is a limit to how small magnetic grains can be practically achieved.

The alternate magnetic medium being explored is a patterned medium, wherein the magnetic portions alternate with non-magnetic portions. For example, a bit patterned medium may have magnetic portions that define magnetic domains with islands surrounded by non-magnetic portions. The track patterned medium may have a center track of magnetic portions separated by, for example, non-magnetic portions.

While various alternatives have been proposed to manufacture such media, there remains a need to find ways to be cost effective and compatible with large volume manufacturing. It is in this context that embodiments of the present disclosure arise.

The ideas and methods of the present disclosure allow high volume fabrication of magnetic media in which some portions of the magnetic film are rendered to exhibit different magnetic properties than other portions of the magnetic film.

In an aspect, this disclosure is a method of patterning a magnetic thin film on a substrate. The method includes providing a pattern for a magnetic thin film, wherein selective regions of the pattern allow penetration of the activated ions of one or more elements through portions of the magnetic thin film and impingement thereon . Activated ions of one or more elements are generated with sufficient energy to penetrate selective regions of the pattern and portions of the magnetic thin film adjacent to the selective regions. The substrate is arranged to receive activated ions. Portions of the magnetic thin film adjacent to the selective regions are rendered to exhibit different magnetic properties than other optional portions of the magnetic thin film.

In another aspect, the disclosure is a method for patterning magnetic media having both sides having magnetic thin films on both sides. The method includes providing a pattern for a magnetic thin film on both sides of the magnetic medium, wherein the selective areas of the pattern include penetration through portions of the magnetic thin film of activated ions of one or more elements and / Allowing them to collide with the top. Activated ions of one or more elements are generated with sufficient energy to penetrate selective areas of the pattern on both sides of the magnetic medium and a portion of the magnetic thin film adjacent to the selective areas. The magnetic medium is arranged to receive the activated ions. Portions of the magnetic thin film adjacent to the selective regions on both sides of the magnetic medium are rendered to exhibit different magnetic properties than other optional portions of the magnetic thin film.

These and other aspects and features of the present invention will become apparent to those skilled in the art upon review of the following description of specific embodiments of the invention in connection with the accompanying drawings,
1 is a process flow diagram of an exemplary method of the present disclosure;
2 is a partial plan view of an exemplary mask for use with a magnetic thin film as a pattern;
Figure 3 is an exemplary resist with a pattern disposed for a magnetic thin film;
4 is a schematic view of a process chamber for use with the present disclosure, showing a first disc holder apparatus of the present disclosure;
5 is a cross-sectional representation of a pattern for a magnetic thin film;
6 is a cross-sectional representation of a magnetic thin film after ion penetration;
Figures 7A and 7B show a helium ion infiltration profile through the resist and the magnetic thin film;
Figure 7c shows the magnetization curves for portions of the magnetic film that are not subjected to helium ion implantation;
Figure 7d shows the magnetization curve for a portion of the magnetic film subjected to helium ion implantation;
Figures 8A and 8B show the boron ion penetration profile through the resist and the magnetic thin film;
Figure 8c shows the concentration of boron and cobalt ions in the magnetic film after boron ion penetration;
Figure 8d shows the magnetization curve for a portion of the magnetic film that is not subjected to boron ion implantation;
8E shows the magnetization curve for a portion of the magnetic film subjected to helium ion implantation;
FIG. 9A shows a silicon ion infiltration profile through a magnetic thin film; FIG.
9B shows the depth profile of the silicon ions in the magnetic thin film after the silicon ion implantation.

The present disclosure will now be described in detail with reference to the drawings, which are provided as illustrative examples of the present disclosure in order to enable those skilled in the art to practice the present disclosure. In particular, the drawings and examples below are not intended to limit the scope of the present disclosure in a single embodiment, but other embodiments are possible by way of interchange of some or all of the elements described or described. In addition, certain elements of the present disclosure may be implemented in whole or in part using known components, and only those portions of these known components that are necessary for the understanding of this disclosure will be described, Will be omitted so as not to obscure the present disclosure. In the present specification, an embodiment showing a single component should not be regarded as a limitation; Rather, unless expressly stated otherwise herein, the present disclosure is intended to encompass other embodiments including a plurality of the same components, and vice versa. Also, applicants do not intend for any term in the detailed description or the claims to be in the unusual or particular sense unless expressly so set forth. In addition, the present disclosure includes current and future known equivalents to known components as referred to herein in an illustrative manner.

In general, the present disclosure contemplates providing a pattern with selective regions that allow penetration of ions of one or more elements through portions of the magnetic thin film and impacts on portions of the magnetic thin film. Active ions of one or more elements having sufficient energy to penetrate selective regions of the pattern and portions of the magnetic thin film adjacent to the selective region are produced. The substrate is arranged to receive the activated ions. Portions of the magnetic thin film adjacent to the selective regions are rendered to exhibit different magnetic properties than other portions of the magnetic thin film. The method is applicable to hard disk drive manufacture and allows very high public density information storage.

An exemplary method of present disclosure is shown in FIG. A method for patterning a magnetic thin film on a substrate includes the steps of: (1) providing a pattern for the magnetic thin film, wherein the selective areas of the pattern are formed by implanting activated ions of one or more elements Allowed; (2) generating activated ions of one or more elements having sufficient energy to penetrate selective regions of the pattern and portions of the magnetic thin film adjacent to the selective regions; (3) disposing the substrate to receive the activated ions; And (4) rendering portions of the magnetic thin film adjacent to the selective regions to exhibit magnetic properties different from other optional portions of the magnetic thin film.

In one embodiment, a mask that does not contribute to the penetration of activated ions having selective regions that allow penetration of ions may be used as the pattern. Figure 2 shows a partial plan view of an exemplary mask 200 for use with a magnetic thin film as a pattern. For example, the mask 200 may include polymeric materials having portions 202 that do not contribute to the penetration of activated ions and selective regions 204 that contribute to the penetration of activated ions, such as polyvinyl alcohol (PVA) material. An exemplary method of generating PVA templates is described by Schaper in U.S. Patent No. 6,849,558, which is incorporated herein by reference. Schaper's teachings can be adapted to produce a mask 200 having portions 202 that do not contribute to the penetration of the activated ions and selective regions 204 that contribute to the penetration of the activated ions. For example, the thickness of the portions 202 may be selected such that the activated ions do not penetrate completely through the portions 202. [ Although portions 202 are shown in a circular fashion, the shape and location of portions 202 may be advantageously chosen, as will be appreciated by those skilled in the art. For example, the shape of the portions 202 may be elliptical, square, rectangular, or any other shape depending on the needs of the present disclosure.

In yet another embodiment, a resist may be coated over the magnetic thin film, for example using nanoimprint lithography, and a pattern may be created in the resist. There are two known types of nanoimprint lithography applicable to this disclosure. The first is thermoplastic nanoimprint lithography [T-NIL], which includes the following steps: (1) coating a substrate with a thermoplastic polymeric resist; (2) contacting a mold having a desired three-dimensional pattern with a resist and applying prescribed pressure; (3) heating the resist beyond the glass transition temperature of the resist; (4) the mold is pressed into the resist when the resist exceeds its glass transition temperature; (5) cooling the resist and separating the mold from the resist, leaving the desired three-dimensional pattern in the resist.

A second type of nanoimprint lithography is Photonano Imprint Lithography (P-NIL), which includes the following steps: (1) adding a photo-curable liquid resist to a substrate; (2) the mold is pressed into the liquid resist until a transparent mold having the desired three-dimensional pattern forms a contact with the substrate; (3) curing the liquid resist to ultraviolet light to convert the liquid resist to a solid; (4) separating the mold from the resist while leaving the desired three-dimensional pattern in the resist. In P-NIL, the mold is made of a transparent material such as fused silica.

Figure 3 shows a cross-sectional representation of an exemplary pattern 300 after nanoimprint lithography. The patterned resist 310 on the magnetic film 320 on the substrate 330 is shown having a depression 340 with selective areas 350 where the resist is substantially removed. However, the selective regions 350 leave a small amount of resist covering the surface of the magnetic thin film 320. [ This is typical for nanoimprint processes. When the resist pattern is used as a mask for ion implantation, the entire resist layer need not be removed in the regions to which the implantation species are to be implanted. However, the remaining layer must be thin enough that a substantial barrier to the implant species will not penetrate through it. Also, the contrast between the areas of thick resist and thin residual resist should be large enough so that the resist in areas with thick resist can stop the ion species before the ion species reach the magnetic thin film. Alternatively, the thin remaining resist in the selective regions 350 may be removed using an anisotropic resist removal process such as a descum process or a slight ash process or any other suitable technique .

In nanoimprint lithography, when the imprint process removes the resist to form the selective regions 350, the mold having a plurality of protrusions corresponding to the recesses 340 is brought into contact with the resist, It is necessary to control the amount of the gas. The width w of the recess 340 may be approximately the same dimension as the depth d of the recess 340 and the height h of the resist may be substantially the same as the depth d of the recess 340. In order to control the amount of resist removed during the stamping process, Is at least as high as the depth d of the concave portion 340. If the depth d of the recess 340 is substantially higher than the width w of the recess 340, the amount of resist displaced is so large that the pattern from the mold is accurately transferred to the resist 310 It can be impractical.

The nanoimprint lithography process can be implemented using a full disk nanoimprint method wherein the mold is large enough to imprint an entire surface. Alternatively, a step and repeat imprint process may be used. In a preferred embodiment, a full disk scheme is used. The nanoimprint process can also be performed on both sides at one time. For example, the disc may be first coated with a layer of resist on both sides. The disc is then subjected to pressure, in which case the molds are pressed against both sides of the disc to simultaneously imprint the desired pattern on both sides of the disc.

Conventional photolithographic processes may also be used, in which case the photoresist is spinned on the disks, followed by exposure of the resist through the mask and development of the exposed resist.

After patterning, the disks have a pattern of resist with selective areas 350 of the pattern that allow penetration and impingement of the activated ions into portions of the magnetic film 320 adjacent to the selective regions 350. Portions of the resist other than the optional regions 350, e.g., portion 360, have a thickness sufficient to prevent transmission of the activated ions, thereby causing the activated ions to collide on the magnetic thin film prevent.

If the mask 200 is used instead, the mask 200 is disposed adjacent to the magnetic thin film and the selective regions 204 of the mask 200 are exposed to the penetration of the activated ions through the mask and to the selective regions 204 Will allow collisions with portions of adjacent magnetic thin films. In one embodiment, the mask 200 is positioned adjacent to the magnetic thin film. In another embodiment, the mask 200 is placed in contact with a magnetic film covered with a magnetic film or coating. The coating can contribute to the adhesion of the mask. The coating may also function as a protective coating on the magnetic film. The coating can be a carbon layer that acts as a protective coating on the magnetic film.

Referring now back to FIG. 1, in step 104, activated ions of one or more elements having sufficient energy to penetrate selective regions of the pattern and impinge on portions of the magnetic thin film adjacent to the selective regions are generated. In one embodiment, a vacuum chamber is provided and one or more gases containing compounds of one or more elements are implanted. The plasma is ignited using a high voltage and the activated ions of one or more elements are discharged.

In step 106, the substrate is placed to receive the activated ions. In one embodiment, the substrate is disposed in a vacuum chamber in which activated ions of one or more elements are generated. In one embodiment, the substrate is disposed in a plasma containing one or more activated ions. In one embodiment, the substrate is biased to attract activated ions. When the mask 200 is used, the activated ions pass through the selective regions 204 of the mask 200 and impinge on portions of the magnetic thin film adjacent to the selective regions 240. When the resist 310 is used as a pattern, the activated ions pass through the selective regions 350 and collide with portions of the magnetic thin film adjacent to the selective regions 350. In one embodiment, the activated ions penetrate into portions of the magnetic film adjacent to the selective regions 350. In one embodiment, the activated ions partially penetrate the portions of the magnetic film adjacent to the selective regions 350. In one embodiment, the activated ions substantially penetrate the portions of the magnetic film adjacent to the selective regions 350. [

In one embodiment, plasma ion implantation may be used to provide a high implant dose at low energies. Since sputtered magnetic films are typically only a few tens of nanometers thick, low ion energies are effective and high doses provide high throughput. Further, as is clear from Fig. 4, plasma ion implantation on both sides of the disks can be performed simultaneously. Although double-sided plasma ion implantation is preferred, single-sided plasma ion implantation can be used without deviating from the teachings of this disclosure. In single-sided plasma ion implantation, the first side will be implanted, then the disk will be inverted and the second side will be implanted.

A plasma ion implantation tool 400 configured to handle the discs is shown in Figure 4, which includes, for example, a magnetic thin film, having a pattern for the magnetic thin film and having one or more elements Lt; RTI ID = 0.0 > of the < / RTI > pattern of magnetic thin films.

Referring to FIG. 4, the chamber 410 is held under vacuum by a vacuum pump 420. A gas supply 430 is connected to the chamber 410 by a pipe 432 and a valve 435. More than one gas may be supplied through valve 435 and multiple gas supplies and valves may be used. For example, dopant gases containing one or more species elements may be supplied to the chamber 410. The rod 440 holds the disks 450. A radio frequency (RF) power supply 460 is connected between the rod 440 and the walls of the chamber 410. The walls of the chamber 410 are connected to an electrical earth. In addition to the RF power supply, a power supply and an impedance matching device for applying a direct current (DC) bias may be included. The rod 440 may be coated with graphite or silicon to protect it from the plasma. The rod and its surface are also highly conductive to facilitate good electrical contact between the rod and the disks. The disks 450 may be held in place using clamps 455 or other means; The clamps 455 not only secure the disks 450 in place, but also ensure good electrical connection between the disks 450 and the rod 440. The load is configured to carry many disks (only three disks 450 are shown for ease of illustration). The chamber 410 is also configured to hold a number of rods loaded with disks for simultaneous plasma ion implantation. The rods 440 are easily moved into and out of the chamber 410.

Processing of the disks in the plasma ion implantation tool 400 proceeds as follows. One or more of the disks 450 are loaded on the rod 440. The rod 440 is loaded into the chamber. The vacuum pump 420 operates to achieve the desired chamber pressure. The desired gas-containing injection species is leaked from the gas supply 430 through the valve 435 to the chamber until the desired operating pressure is reached. The RF power supply 460 is operated to ignite the plasma surrounding the surfaces of one or more of the disks 450. The DC power supply can be used to control the energy of ions implanted into the magnetic thin film. RF biasing can also be used.

The ions that can be easily injected from the plasma and are effective in modifying the magnetic properties of typical sputtered magnetic films such as Co-Pt and Co-Pd include: hydrogen, helium, boron, sulfur, aluminum, lithium, neon and germanium, It is a combination of elements. This list is not complete. Any ions that are easily formed in the plasma and effective to modify the magnetic properties of the magnetic thin film will suffice. Ideally, ions that can change the magnetic properties of the magnetic thin film to the less thermally stable, less magnetic or more magnetic regions in the smallest amount would be desirable.

Further details of plasma ion implantation chambers and process methods are available in U.S. Patent Nos. 7,288,491 and 7,291,545 to Collins et al., All of which are incorporated herein by reference. The main difference between the chamber of this disclosure and the chamber of Collins et al. Is the different configuration for holding the substrate. The disc holders of this disclosure enable the injection of both sides at one time, while the substrates at Collins et al. Are placed on a wafer chuck during processing. Those skilled in the art will understand how plasma ion implantation tools and methods such as Collins et al. Can be utilized in this disclosure.

After placing the substrate to receive the activated ions in step 106, in step 108, a portion of the magnetic thin film adjacent to the selective areas is subjected to thermal excitation. In one embodiment, radio frequency or microwave energy may be used to heat the selective regions. In yet another embodiment, the substrate may be heated. In yet another embodiment, laser or flash annealing may be performed. In some embodiments, a rapid thermal anneal or furnace may be used.

As will be appreciated by those skilled in the art, the thermal excitation step 108 can be performed with the resist layer still on the magnetic thin film. In some embodiments, the resist layer can be removed and the magnetic film is subjected to thermal excitation. In this embodiment, a magnetic thin film having both portions subjected to ion implantation and portions not subjected to ion implantation will be applied to the thermal excitation. This approach can be advantageously used, for example, with certain types of magnetic films that may benefit from thermal excitation on portions of the magnetic film that are not ion implanted.

If a mask 200, e.g., a PVA mask, is used, the process may further include removal of the mask 200. In one embodiment, the PVA mask may be removed, for example, using a process to dissolve the PVA mask 200 using an aqueous solution. In some embodiments, a non-aqueous solution may be used. In some embodiments, after the mask 200 is removed, the magnetic thin film is subjected to thermal excitation. In this embodiment, a magnetic thin film having both portions subjected to ion implantation and portions not subjected to ion implantation will be subjected to thermal excitation. This approach can be advantageously used, for example, with certain types of magnetic films that may benefit from thermal excitation on portions of the magnetic film that are not ion implanted. In some embodiments, the thermal excitation step 108 may be performed with the mask 200 still present.

In some embodiments, the magnetic thin film may be thermally excited in the chamber 410 of the ion implantation tool 400 by incorporating an appropriate heat source in the chamber and selectively turning on the heat source after ion implantation.

After thermal excitation at the activated ion step 106 and / or at step 108, portions of the magnetic thin film adjacent to the selective regions exhibit different magnetic properties than the other alternative regions as shown in step 110 Lt; / RTI > In one embodiment, the activated ions that penetrate into portions of the magnetic thin film adjacent to the selective regions 350 render such that portions of the magnetic thin film adjacent to the selective regions exhibit magnetic properties that are different from other optional regions. When the resist is used as a pattern, the process may further include a resist stripping step. The resist stripping step may be facilitated by conventional discom and ash operations in the plasma ion implantation chamber prior to removal of the discs. The resist stripping step may be a wet chemical process known in the art. In some embodiments, the resist stripping step may be performed prior to the thermal excitation step 108 as described above.

The energy of the ions available from the plasma implantation process is in the range of about 100 eV to about 15 keV. However, for implantation into magnetic thin films tens of nanometers thick, the preferred energy range is from about 1 keV to about 11 keV. The selected energy range is based on the selected element, resist thickness, resist ion stop capability, and desired magnetic properties. For example, bias voltages of about 1 kV to about 11 kV may be used to produce the desired energy range.

5 is a cross-sectional representation of the pattern 510 disposed relative to the magnetic thin film 520, and arrows 530 represent the general direction of impact of the activated ions. The activated ions penetrate through the selective regions 540 of the resist 510 and penetrate the portion 550 of the magnetic thin film 520 adjacent to the selective regions 540.

6 is a cross-sectional representation of the magnetic thin film 520 after ion implantation in which portions 550 have been implanted. The portions 550 of the magnetic thin film 520 are rendered to exhibit different magnetic properties than the other optional portions 560 of the magnetic thin film 520. [

The following examples are provided to illustrate the various applications of ion implantation to achieve desired magnetic properties.

Examples:

Experiments were performed to determine the ion stopping properties of the resist for helium and boron ions for a given bias voltage.

Helium ion implantation: Experiments were performed for helium ion implantation at 7 kV and 2 kV bias voltages. At 7 kV, the resist thickness required to stop the penetration of helium ions through the resist layer was about 120 nm. The resist thickness in selected regions of the pattern may be as high as 45 nm and still provide for penetration of helium ions through the 20 nm thick Co-based magnetic film adjacent to the selective regions of the pattern. At 2 kV, the resist thickness required to stop the penetration of helium ions through the resist layer was about 85 nm. The resist thickness in selected areas of the pattern may be as high as 10 nm and still provide for the penetration of helium ions through the 20 nm thick Co-based magnetic film adjacent to the selective areas of the pattern.

Boron ion implantation: An experiment was performed for boron ion implantation at a 9 kV bias voltage. At 9 kV, the resist thickness required to stop the penetration of boron ions through the resist layer was about 65 nm. The resist thickness in selected areas of the pattern may be as high as 10 nm and still provide for the infiltration of boron ions through the 20 nm thick Co-based magnetic film adjacent to selective areas of the pattern.

Magnetic properties:

Example 1a:

A glass substrate sputtered with a FeNi alloy soft underlayer of about 100 nm was used. Approximately 20 nm magnetic thin film layer of CoCrPt alloy was sputtered on the FeNi alloy soft underlayer. The above prepared sample is treated with a plasma containing He ions, by injecting a dopant gas helium into the process chamber. The processing chamber pressure was about 15 mtorr, the RF bias voltage was about 2 kV, the source power was about 500 watt, the dopant gas helium was injected at a flow rate of about 300 sccm and the injection time was about 25 seconds. Alternatively, an inert gas may also be injected to assist in the generation of the plasma. For example, argon may also be injected at a flow rate of about 16 sccm.

Penetration of He ions into the sample was profiled using the simulation program with the process parameters described above. A simulation program known as TRIM can be used to perform the simulation. The TRIM program is available as part of a group of programs known as SRIM from www.srim.org. Figures 7A and 7B show the results of the simulation. Referring now to FIG. 7A, it is clear that a resist of approximately 85 nm thickness will be sufficient to prevent active He ions from penetrating into the CoCrPt magnetic thin film layer. Referring now to FIG. 7B, it can be seen that about 10 nm of the resist layer and about 28 angstroms of the carbon layer are successfully penetrated by the activated ions and substantially penetrate through the CoCrPt magnetic thin film layer of about 20 nm. .

The magnetic properties of the magnetic film for the sample without He implantation were measured using a Physical Property Measurement System to establish the baseline. After the samples were subjected to He ion implantation, magnetic properties of portions of the magnetic film subjected to He ion implantation were measured using a physical property measurement system. FIG. 7C shows the magnetization curve for a magnetic film not subjected to He ion implantation. From Fig. 7C, it is evident that the saturation magnetic force Ms is about 1.36 Tesla. Figure 7d shows the magnetization curves for portions of the magnetic film subjected to He ion implantation. 7D, the saturation magnetic force (Ms) for the portion of the magnetic film subjected to the He ion implantation dropped to about 0.1 tesla as compared to the baseline magnetic thin film not subjected to He ion implantation. Thus, the magnetic thin film may be subjected to He ion implantation under suitable process conditions to substantially change the magnetic properties in a state where the selective portion exhibits significantly different magnetic properties.

Example 1b:

Samples similar to those used in Example 1a were used in Example 1b, except that the samples were subjected to thermal annealing. The thermal annealing was performed at about 100 DEG C and about 200 DEG C for about one hour at a vacuum of about 10 Torr to about 5 Torr.

After the samples were subjected to thermal annealing, the magnetic properties of portions of the magnetic film subjected to both He ion implantation and thermal annealing were measured using a physical property measurement system. The baseline magnetization curve for a magnetic film without He implantation represents a saturation magnetization (Ms) of about 1.36 Tesla. The magnetization curves for portions of the magnetic film subjected to both He ion implantation and about 100 < 0 > C thermal annealing showed a saturation magnetization (Ms) of about 0.01 Tesla. The magnetization curves for portions of the magnetic film subjected to both He ion implantation and about 200 < 0 > C thermal annealing showed a saturation magnetization (Ms) of about 0.03 Tesla. Based on the results for the samples in Examples 1a and 1b, it is evident that the thermal annealing of the samples further reduces the saturation magnetization (Ms) for the portions of the magnetic film that have been annealed. Thus, the magnetic thin film can be subjected to both He ion implantation and thermal annealing under appropriate process conditions to substantially change the magnetic properties in a state where the selective portion exhibits significantly different magnetic properties. Although the experiment was conducted at a bias voltage of about 2 kV, the bias voltage may be in the range of 1 kV to 11 kV and preferably in the range of 1 kV to 3 kV.

Example 2:

Samples similar to those used in Example 1a were used for the infiltration of boron ions. As described above, the prepared sample was treated with a plasma containing boron ions by injecting a dopant gas BF3 into the processing chamber. The processing chamber pressure was maintained at about 15 mtorr, the RF bias voltage was about 9 kV, the source power was about 500 watt, and the dopant gas BF3 was injected at a flow rate of about 300 sccm and the injection time was about 20 seconds. Alternatively, an inert gas may also be injected to assist in the generation of the plasma. For example, argon may be injected at a flow rate of about 16 sccm.

Penetration of boron ions into the sample was profiled using a simulation program with the process parameters described above. Figures 8A and 8B show the results of the simulation. Referring now to FIG. 8A, it is clear that a about 65 nm thick resistor is sufficient to prevent the activated boron ions from penetrating into the CoCrPt magnetic thin film layer. It can be seen from Figure 8A that about 10 nm of the resist layer and about 28 angstroms of the carbon layer can be successfully penetrated by the activated ions. The activated ions can also substantially penetrate through the CoCrPt magnetic thin film layer of about 20 nm.

Referring to FIG. 8C, the concentrations of boron and Co atoms were determined using a secondary ion mass spectrometer (SIMS). From FIG. 8C, it is evident that the Co concentration left is substantially unchanged. In addition, the boron concentration remained constant for about 10 nm depth and then decreased gradually.

The magnetic properties of the magnetic film for samples not subjected to boron ion implantation were measured using a physical property measurement system to establish a baseline. After the sample was subjected to boron ion implantation, the magnetic film subjected to the boron ion implantation was measured using a physical property measurement system. Figure 8d shows the magnetization curves for the magnetic films without boron ion implantation. From Fig. 8D, it is clear that the saturation magnetic force Ms is about 1.36 Tesla. Figure 8E shows the magnetization curves for portions of the magnetic film subjected to boron ion implantation. 8E, the saturation magnetic force (Ms) for the portion of the magnetic film subjected to the boron ion implantation dropped to about 0.5 Tesla, as compared to the magnetic thin film not subjected to the boron ion implantation. The boron ion implantation under these experimental conditions reduced the magnetization by about 50%.

Thus, the magnetic thin film may be subjected to boron ion implantation under certain process conditions to alter the magnetic properties of the selective portion to exhibit significantly different magnetic properties. For example, the magnetic properties of the selective portions can be altered to lessen the magnetic properties than the portions that are not subjected to boron ion implantation. Although the experiment was conducted at a bias voltage of about 9 kV, the bias voltage may range from 1 kV to 11 kV and preferably from 7 kV to 11 kV.

Example 3:

A silicon substrate sputtered with a Co alloy layer of about 20 nm was prepared as samples for this example. The prepared sample was treated with plasma containing silicon ions by injecting a dopant gas SiH4 into the process chamber. The processing chamber pressure was about 30 mtorr, the RF bias voltage was about 9 kV, the source power was about 500 watt, and the dopant gas SiH4 was injected at a flow rate of about 75 sccm and the injection time was about 20 seconds.

Penetration of the silicon ions into the sample was profiled using the simulation program with the process parameters described above. Figure 9A shows the results of the simulation. Referring now to FIG. 9A, it is clear that Si penetrates to a depth of about 5-6 nm, in some cases to a depth of 10 nm.

After the sample was subjected to silicon ion implantation, the depth profile of Si implantation in the 20 nm Co film was measured using SIMS. Figure 9b shows the depth profile for Si implantation. From Figure 9b it is clear that the Si ions have penetrated about 5-6 nm in depth. It is noteworthy that the profiling Si penetration depth using a simulation program is well correlated with the actual measurement of Si penetration depth.

In some embodiments, after ion implantation, the magnetic thin film may be subjected to thermal excitation, for example, by thermal annealing. It is expected that thermal annealing will further reduce the saturation magnetization (Ms) of the portions of the magnetic thin film that have been thermally excited, as is apparent from Example 1b.

The resist thickness required to stop the penetration of the activated ions through the resist layer and the collision with the magnetic thin film is dependent on the species of elements being used, the process parameters, and the selective areas of the resist layer that allow penetration of charged ions It is clear from the above examples that it depends on the desired depth of penetration of ions into adjacent magnetic films. As the dimensions of the selective areas of the resist layer that allow the penetration of charged ions become smaller, there is a need to reduce the resist thickness to allow an effective nanolithographic process during pattern generation. As the resist thickness decreases, the resist layer may no longer be able to stop the penetration of the activated ions in regions other than the selective regions.

One way to overcome this problem is to add a dopant to the resist which increases the resistance to penetration of charged ions. For example, the resist may be doped with a silicon-containing compound to increase resistance to penetration of charged ions through the resist. Other dopants that can be used to increase the resistance to penetration of charged ions include compounds containing sulfur and phosphorus. In one embodiment, nanoparticles can be added as additives to adjust the resistance to penetration of charged ions. For example, nanoparticles of titanium dioxide (TiO2), ceria (CeO2), silicon dioxide (SiO2), and aluminum oxide (Al2O3) can be used to control the resistance to penetration of charged ions.

It is clear from the above examples that the different element species have different effects on the magnetic properties based on the process parameters and the desired penetration depth of ions into the magnetic thin film. For example, one or more of the elements may be advantageously used to modify the magnetic properties of the magnetic thin film. As an example, a combination of helium and boron may provide additional advantages. For example, helium with a lower molecular weight can penetrate deeper into a magnetic thin film and change magnetic properties using less bias voltage. Boron having a higher molecular weight can be used before or after penetration of helium to further affect the magnetic properties of the magnetic thin film and to function as a barrier to helium ions from deviating from the magnetic thin film over time.

Although a combination of helium and boron has been described, one skilled in the art will appreciate that various other substitutions and combinations of elements may be used sequentially or together to derive magnetic and other properties favorable to the improvement and retention of modifications of magnetic properties I will understand.

It is also apparent from the above examples that different element species can be used to modify the magnetic properties of the magnetic thin film. For example, a compound containing elements that increase the magnetic properties of the thin film upon ion implantation may be used. For example, platinum ion implantation can increase the magnetic properties of magnetic thin films.

The present disclosure can be used for various types of magnetic recording media. For example, the teachings of the present disclosure may be used with recording media having a granular magnetic structure. The present disclosure may be used for multi-layered magnetic films. The magnetic film may also be a continuous magnetic film and may be used with the patterned media. The patterned medium may be a bit patterned medium or a track patterned medium. In one embodiment, the magnetic thin film can be made of a high anisotropic magnetic material suitable for heat-assisted magnetic recording.

This disclosure allows very short process times. For example, it may take about 10 seconds to inject a disc. The input and output vacuum load locks will allow rapid transfer of the disks into and out of the chamber and will avoid wasting time during pump down, thus allowing very high throughput. Those skilled in the art will understand how automated transfer systems, robotics and loadlock systems can be integrated with the plasma ion implanter of this disclosure.

In certain embodiments, the present disclosure provides a method for selectively modifying magnetic properties of portions of a magnetic thin film of a magnetic medium. Optional modifications can be advantageously used to increase one or more of the desired properties, such as the public density, the recording-ability, the SNR and the thermal stability of the magnetic medium.

Although the present disclosure has been particularly described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that changes and modifications in form and details may be made without departing from the spirit and scope of the present disclosure Should be readily apparent to anyone. The appended claims are intended to cover such modifications and variations.

Claims (25)

A method for patterning a thin film on a substrate,
Disposing a magnetic thin film on the substrate;
Disposing a pattern on the magnetic film having selective areas that allow penetration of energized ions;
Positioning the substrate having the pattern thereon in a chamber;
Sequentially injecting helium and boron-containing gases into the chamber, wherein the helium and the boron-containing gas are helium and boron-containing gases, the helium and the boron- And sequentially ionized with a plasma to implant boron ions, and during the implant, the substrate is biased within a range of 1 kV to 11 kV;
And rendering portions of the magnetic thin film adjacent to the selective regions to exhibit magnetic properties different from other optional portions of the magnetic thin film.
A method for patterning a thin film on a substrate. The method according to claim 1,
Wherein disposing the pattern comprises positioning the mask in proximity to the magnetic thin film.
A method for patterning a thin film on a substrate. 3. The method of claim 2,
Wherein the mask comprises polyvinyl alcohol,
A method for patterning a thin film on a substrate. The method according to claim 1,
Wherein the step of arranging the pattern comprises:
Depositing a resist on the surface of the magnetic thin film;
Contacting the resist with a mold having a three-dimensional pattern to create depressions in the resist, the recesses creating regions of thin resist and regions of thick resist, Said thin film resist corresponding to said selective areas allowing penetration of activated ions; And
Curing the resist
/ RTI >
A method for patterning a thin film on a substrate. 5. The method of claim 4,
The activated ions having sufficient energy to penetrate the thin film resist to contact the magnetic thin film,
A method for patterning a thin film on a substrate. 6. The method of claim 5,
And removing the resist.
A method for patterning a thin film on a substrate. 6. The method of claim 5,
The resist is deposited and cured on the surface of the magnetic thin film using thermoplastic nanoimprint lithography or photonanoimprint lithography,
A method for patterning a thin film on a substrate. 6. The method of claim 5,
Wherein disposing the pattern on the magnetic thin film comprises disposing a pattern on both sides of the substrate.
A method for patterning a thin film on a substrate. 1. A method for patterning a magnetic thin film on a substrate,
Disposing a pattern on the magnetic thin film, wherein selective regions of the pattern allow activated ions of one or more elements to contact portions of the magnetic thin film;
Generating activated ions of one or more elements having sufficient energy to penetrate the selective regions of the pattern and a portion of the magnetic thin film adjacent to the selective regions;
Exposing the substrate to the activated ions such that the activated ions are in contact with the magnetic thin film;
Applying a portion of the magnetic thin film adjacent to the selective regions to thermal excitation; And
And rendering portions of the magnetic thin film adjacent to the selective regions to exhibit magnetic properties different from other optional portions of the magnetic thin film.
A method for patterning a magnetic thin film on a substrate. delete 10. The method of claim 9,
Wherein applying the portion of the magnetic thin film adjacent to the selective regions to the thermal excitation further comprises applying to the thermal excitation other optional portions of the magnetic thin film.
A method for patterning a magnetic thin film on a substrate. 12. The method of claim 11,
Further comprising the step of removing said pattern for said optional other portions prior to applying said selectively different portions of said magnetic thin film to a thermal excitation.
A method for patterning a magnetic thin film on a substrate. 10. The method of claim 9,
Wherein the step of arranging the pattern comprises coating a resist on top of the magnetic thin film and imprinting the mold with a plurality of projections corresponding to the selective areas of the pattern, Wherein the resist surrounding the recess has a resist thickness at least as high as the depth of the recess and the thickness of the resist surrounding the recess surrounds the recess Is sufficient to substantially prevent penetration of activated ions through the resist,
A method for patterning a magnetic thin film on a substrate. 14. The method of claim 13,
Wherein applying the portion of the magnetic thin film adjacent to the selective regions to the thermal excitation comprises heating the magnetic thin film by laser annealing, flash annealing, rapid thermal annealing, or microwave energy application.
A method for patterning a magnetic thin film on a substrate. 10. The method of claim 9,
Wherein disposing the pattern comprises coating a resist on top of the magnetic thin film and imprinting the mold with a plurality of protrusions corresponding to the selective areas of the pattern.
A method for patterning a magnetic thin film on a substrate. delete delete delete delete delete delete delete delete delete delete

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