Magnetic Lithography Research Articles

Magnetic resonance lithography

Magnetic resonance lithography

Magnetolithography: From Bottom‐Up Route to High Throughput

Magnetic lithography is based on a magnetic mask installed on the back of a substrate and the magnet that is set under the mask, which induce a magnetic field toward the substrate through the pattern of the masks. Magnetic nanoparticles are immobilized on selective locations, where the mask induces a magnetic field, resulting in patterned substrates (see image).

Biomolecular Nanopatterning by Magnetic Electric Lithography

Biomolecular Nanopatterning by Magnetic Electric Lithography

Soft magnetic lithography and giant magnetoresistance in superconducting/ferromagnetic hybrids

We demonstrate an approach to create a tunable pinning potential in a superconducting/ferromagnetic (SC/FM) hybrid, allowing the switching of their electronic properties through the application of a small magnetic field. Using direct magneto-optical imaging, macroscopic transport, and magnetic measurements, we show that the alignment of stripe domains in the ferromagnet provides a remarkable directionality for the superconducting vortex motion. An analysis of the anisotropic flux motion demonstrates a substantial critical current anisotropy in the superconductor. The possibility of aligning stable lattices of stripe domains in select directions using in-plane magnetic fields allows the realization of soft magnetic lithography for efficient manipulation of supercurrent flow in SC/FM bilayers. Furthermore, in our samples we observed a pronounced magnetoresistance effect yielding 4 orders of magnitude resistivity change in a few millitesla in-plane field.

Magnetic lithography for servowriting applications using flexible magnetic masks nanofabricated on plastic substrates

Magnetic lithography (ML) is a process qualitatively analogous to contact optical lithography which transfers information from a nanopatterned magnetic mask (analog of optical photomask) to magnetic media (analog of photoresist), and is interesting for applications in instantaneous parallel magnetic recording, in particular for servowriting applications. The magnetic mask consists of nanopatterned magnetically soft material (FeNiCo, FeCo) on a thin flexible plastic substrate, typically Polyethylene teraphtalate (PET) or polyimide. When uniformly magnetized media is brought into intimate contact with the magnetic mask, an externally applied magnetic field selectively changes the magnetic orientation in the areas not covered with the soft magnetic material. Flexible substrate of the magnetic mask offers superior compliance to magnetic media which is likely to have imperfect flatness and surface particulate contamination. We discuss nanofabrication challenges of magnetic masks on plastic substrates, including electron beam lithography, electroplating and lift-off processing on the nanometer scale, adhesion of metal thin films on PET and polyimide substrates, and release of plastic films from rigid substrates used during the processing. We present results on fabricated magnetic masks, magnetic force microscopy images of the magnetic transition patterns and disk spinstand tests of servowritten patterns.

Microcrystalline silicon prepared at magnetic field modified nucleation

We present a complex characterization of thin silicon films, the growth of which has been influenced by permanent magnet, placed under the substrate. The pattern of microcrystalline regions in otherwise amorphous film varied with the orientation of the magnetic field. Study by atomic force microscopy and by micro-Raman spectroscopy revealed that the microcrystalline regions resulted from increased nucleation density of crystalline grains at the locations where the magnetron effect could be expected. This phenomenon allowed us to study in detail the transition between amorphous and microcrystalline growth. Moreover, it can be used as a kind of ‘magnetic lithography’ for preparation of predefined microcrystalline patterns in otherwise amorphous silicon films.

Patterning of hydrogenated microcrystalline silicon growth by magnetic field

A way of influencing growth of silicon films by magnetic field is demonstrated. Permanent magnet(s) placed under the substrate influenced the discharge in a mixture of silane and hydrogen and led to formation of microcrystalline regions in otherwise amorphous film. The pattern of microcrystalline regions varied with the orientation of the magnetic field. Microscopic study by atomic force microscopy and by micro-Raman spectroscopy revealed that the microcrystalline regions resulted from a higher density of crystalline grain nuclei, increased at the locations where the magnetron effect could be expected. This phenomenon could be used to study the transition between amorphous and microcrystalline growth. Moreover, we suggest it as a kind of “magnetic lithography” for the preparation of predefined microcrystalline patterns in otherwise amorphous silicon films.

Flexible magnetics on plastic substrates: magnetic lithography, magnetic nanostructures and other applications

AbstractFlexible Magneticsencompases the design, fabrication and characterization of magnetic devices and systems built on thin flexible substrates. Although device and system functionality is magnetic in nature, flexible magnetics draws interesting parallels to flexible electronics, especially in the challenge of fabrication on plastic substrates. Some of those challenges include substrate surface quality and maximum processing temperature, tooling issues related to mechanical properties of flexible substrates, adhesion of thin films deposited on plastics, as well as thermal stability of fabricated devices.One application of flexible magnetics relevant to the information storage industry is magnetic lithography. Magnetic lithography is a process qualitatively analogous to contact optical lithography. Magnetic lithography transfers information from a patterned magnetic mask (analogous to the optical photomask) to magnetic media (analog of the photoresist), and is interesting for applications in rapid, parallel magnetic recording. The magnetic mask consists of patterned magnetically soft material (FeNiCo, FeCo) on a thin flexible plastic substrate, typically Polyethylene Teraphtalate (PET) or polyimide. When uniformly magnetized media is brought into intimate contact with the magnetic mask, an externally applied magnetic field selectively changes the magnetic orientation in the areas not covered with the soft magnetic material. The flexible magnetic mask offers superior compliance to contaminated or nonplanar magnetic media. We discuss nanofabrication challenges of magnetic masks on plastic substrates, including electron beam lithography, electroplating and lift-off processing on the nanometer scale, adhesion of metal thin films on PET and polyimide substrate, and release of plastic films from the rigid substrates used during the processing. We present results on fabricated magnetic masks, and magnetic force microscopy images of the magnetic transition patterns.Besides fabrication of magnetic nanostructures and devices on plastic substrates, we also present our results on nanoscale patterning of plastic thin film. We will present our results on fabrication of sub-100 nm scale nanochannels in polyimide films, as well as self-assembly of ordered arrays of polyimide nanodots. Nanoscale patterned plastic films are interesting for the potential application in magnetic lithography, as well as for the application in micro- and nanofluidics, due to the mechanical flexibility and biological inertness of plastic materials. We will discuss interesting biosensing systems that may result from the combination of magnetic functionality, electronic control and patterned nanofludic channels on plastic substrates.

Magnetic lithography using flexible magnetic masks: applications to servowriting

Magnetic lithography (qualitatively analogous to optical lithography) is a process that transfers information from a patterned magnetic mask (analog of optical photomask) to magnetic media (analog of photoresist). The mask consists of patterned soft magnetic material (FeNiCo, FeCo) deposited on a thin flexible substrate. A flexible magnetic mask is considered a key element for achieving intimate contact between mask and the media. When uniformly magnetized media is brought into contact with the flexible magnetic mask, an externally applied magnetic field selectively changes the magnetic orientation in the areas not contacted by the soft magnetic material. Samples of submicron patterned FeCo and FeNiCo flexible magnetic masks have been fabricated and magnetic transition patterns successfully transferred to hard disk CrCo-based magnetic media. The authors report on the magnetics of the pattern transfer, fabrication of magnetic masks on flexible plastic substrates, magnetic force microscopy images of the magnetic transition patterns, and disk spinstand tests.

Flexible Magnetics: Magnetic Lithography and Fabrication of Magnetic Masks on Thin Plastic Substrates

AbstractFlexible magnetic lithography is a process qualitatively analogous to contact optical lithography which transfers information from a patterned magnetic mask (analog of optical photomask) to magnetic media (analog of photoresist), and is interesting for applications in instantaneous parallel magnetic recording. The magnetic mask consists of patterned soft magnetic material (FeNiCo, FeCo) on a flexible plastic substrate, typically Polyethylene Teraphtalate (PET). When uniformly magnetized media is brought into intimate contact with the magnetic mask, an externally applied magnetic field selectively changes the magnetic orientation in the areas not covered with the soft magnetic material. Flexible substrate of the magnetic mask o.ers superior compliance to magnetic media which is likely to have imperfect flatness and surface particulate contamination.Although magnetic in physical nature, flexible magnetics draws interesting parallels to flexible electronics, especially in challenges of fabrication of sub-micron patterns on thin flexible plastic substrates. We fabricated samples of sub-micron patterned FeCo and FeNiCo magnetic masks on PET substrates by using combined lamination/release process of PET films. Rigid substrates, typically silicon or quartz were initially laminated with PET films and processed using standard fabrication procedures. After completing magnetic mask device fabrication, PET films were released from the rigid substrates.We successfully transferred patterns from magnetic masks to hard disk CrPtCo-based magnetic media. The details of the method, including physics of the magnetic lithography pattern transfer, fabrication of the magnetic mask on flexible PET substrates, lamination and release of PET films, and magnetic force microscopy (MFM) images of the magnetic transition patterns are reported.

Magnetic lithography using a flexible master: A method for instantaneous magnetic recording on media surfaces with flatness imperfections

A method for instantaneous parallel recording on magnetic media using a flexible master has been developed. Magnetic lithography (qualitatively analogous to optical lithography) transfers information from a patterned magnetic mask (analog of optical photomask) to magnetic media (analog of photoresist). The mask consists of patterned soft magnetic material (FeNiCo, FeCo) on a flexible polyethylene tetraphthalate (PET) substrate. When uniformly magnetized media is brought into intimate contact with the magnetic mask, an externally applied magnetic field selectively changes the magnetic orientation in the areas not covered with the soft magnetic material. Imperfect flatness or the presence of particular contaminants can result in local loss of intimate contact between the master and media, resulting in loss of resolution of submicron features in the transferred magnetic pattern. A flexible master, held against the media via an applied pressure, offers superior compliance to imperfections, even at relatively small applied pressures. We fabricated samples of submicron patterned FeCo and FeNiCo magnetic masks, and successfully transferred patterns to hard disk CrPtCo-based magnetic media. The details of the method, including fabrication of the magnetic mask on flexible PET substrates, physics of the magnetic lithography pattern transfer, and magnetic force microscopy images of the magnetic transition patterns are reported.

Production of an Encoder Plate by Magnetic Lithography

By using the magnetic lithography technique previously reported, an optical grating can be easily formed not only on a plane, but also on a convex or concave surface. The optical characteristics of this relief-type grating depend on its cross-sectional shape. To apply this technology to encoder plates, it is important to investigate the factors determining the shape of a grating produced by magnetic lithography. In order to improve the encoder's performance, proper application of magnetic lithography must control the cross-sectional shape of the grating to produce a grating that has no Fraunhofer zeroth-order diffraction light spot. Results show that there is good repeatability in the grating characteristics in production. The conditions for development of such gratings are investigated.

磁気リソグラフィによるエンコード面の作製

By using the magnetic lithography technique previously reported, an optical grating can be easily formed not only on a plane, but also on a convex or concave surface. since the optical characteristics of this relief-type grating depend on its cross-sectional shape, it is important to investigate the factors determining the shape of the grating in magnetic lithography so that this technology can be applied to an encoder plate. In order to improve the encoder's performance, it is necessary to control the crosssectional shape of the grating and to try to produce a grating that has no Fraunhofer zeroth-order diffraction light spot by means of magnetic lithography. Results show that the characteristics of the gratings have good repeatability in production. Conditions for developement of such gratings are investigated.

Relationship Between a Cross Sectional Shape and Developing Conditions in a Grating Made by Magnetic Lithography

A new method, previously reported, for fabricating optical diffraction gratings involves writing a periodic magnetic pattern in a magnetic memory medium and using a magnetic fluid as magnetic toner to render the pattern visible. Using this method, an optical grating can easily be prepared even on convex and concave surfaces. Because the optical characteristics of such relief-type gratings are determined by the cross-sectional shape, it is important that the cross-sectional shape be studied prior to application of the method in encoder plates or optical components. When the grating constant is small, the positions at which the magnetic fluid is deposited change from domain walls to magnetic domains. By analyzing the Fraunhofer diffraction pattern of such gratings, the relationship between cross-sectional shape and developing conditions was investigated. According to the results, the shape is that of a sinusoidal or circular arc when the grating constant is less than 10 μm.