Classifications

• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/20—Exposure; Apparatus therefor
  • G03F7/2022—Multi-step exposure, e.g. hybrid; backside exposure; blanket exposure, e.g. for image reversal; edge exposure, e.g. for edge bead removal; corrective exposure
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B11/00—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor
  • G11B11/10—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor using recording by magnetic means or other means for magnetisation or demagnetisation of a record carrier, e.g. light induced spin magnetisation; Demagnetisation by thermal or stress means in the presence or not of an orienting magnetic field
  • G11B11/105—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor using recording by magnetic means or other means for magnetisation or demagnetisation of a record carrier, e.g. light induced spin magnetisation; Demagnetisation by thermal or stress means in the presence or not of an orienting magnetic field using a beam of light or a magnetic field for recording by change of magnetisation and a beam of light for reproducing, i.e. magneto-optical, e.g. light-induced thermomagnetic recording, spin magnetisation recording, Kerr or Faraday effect reproducing
  • G11B11/10582—Record carriers characterised by the selection of the material or by the structure or form
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
  • G11B5/84—Processes or apparatus specially adapted for manufacturing record carriers
  • G11B5/8404—Processes or apparatus specially adapted for manufacturing record carriers manufacturing base layers
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
  • G11B5/84—Processes or apparatus specially adapted for manufacturing record carriers
  • G11B5/855—Coating only part of a support with a magnetic layer
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
  • G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
  • G11B7/26—Apparatus or processes specially adapted for the manufacture of record carriers
  • G11B7/261—Preparing a master, e.g. exposing photoresist, electroforming
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/20—Exposure; Apparatus therefor
  • G03F7/2051—Exposure without an original mask, e.g. using a programmed deflection of a point source, by scanning, by drawing with a light beam, using an addressed light or corpuscular source
  • G03F7/2059—Exposure without an original mask, e.g. using a programmed deflection of a point source, by scanning, by drawing with a light beam, using an addressed light or corpuscular source using a scanning corpuscular radiation beam, e.g. an electron beam

Definitions

• the present invention relates to a method, a device and a computer program product for forming, by exposure to a lithographic beam, a groove of a material, exposed to a predetermined degree, in a surface layer of an essentially flat, rotatable substrate.
• the grooves may have a width in the order of 1-100 nanometers.
• lithography A method known for this purpose is referred to as lithography, in which a substrate is exposed to a lithographic beam, for instance a particle beam, such as an ion beam or an electron beam.
• a lithographic beam for instance a particle beam, such as an ion beam or an electron beam.
• a beam can be very small in cross-section.
• a point of exposure is formed, whose area essentially corresponds to the cross-section of the lithographic beam.
• This type of lithography can be used for making a relief pattern for a stamp for imprint lithography, which is described in more detail, for instance, in WO01/42858A1 and WO01/69317, which are incorporated herewith by reference.
• This technology may become interesting in the manufacture of the new generation hard disks, where the sur- face is provided with a structure for high storage capacity.
• magnetizable areas in each of the layers, which areas are separated.
• magnetizable areas can take the form of concentric rings, hereinafter referred to as "grooves" , which are distributed over the surface of a rotatable disk.
• a problem in connection with the making of such concentric grooves involves tolerance variations in the groove made by the lithographic beam, which are caused by mechanical slack or play that arises in the equipment used and that is uncontrollable per se and difficult to handle. This problem occurs especially in conjunction with very small structures being made with great accuracy on a relatively large surface.
• particle beams such as electron or ion beams, since electromagnetic radiation, in case of e.g. optical wavelengths or X-ray wavelengths, usually cannot be focused to the same small dimensions.
• US 5,621,216 discloses a method of handling position errors at spot boundaries when manufacturing X-ray masks for E-beam lithography. This is done by the electron beam resist being partially exposed during a plurality of exposures, whereby an average exposure is achieved.
• the technology suggested in US 5,621,216 is, however, only suited for exposure of small surfaces since the electron beam can only be controlled over a very small area.
• An object of the present invention thus is to provide a method, a device and a computer program product for lithography, by means of which the above problems are wholly or partly eliminated.
• the method is characterized in that the lithographic beam and the axis, during rotation of the substrate about the axis, are controlled relative to each other so that part of the groove is subjected to more than one exposure to the lithographic beam, the groove being formed as a sum of said more than one exposure.
• the predetermined degree to which the groove is exposed is sufficient to enable subsequent treatment of the surface layer, for example, by developing the surface layer when it is in the form of a resist.
• essentially flat is meant that the substrate is sufficiently flat to be exposed to lithographic processing by the lithographic beam.
• the flatness of the substrate and the depth of field of the beam are adapted to each other.
• the lithographic beam and the axis may be held at an essentially constant distance from each other while the substrate is rotated several times about the axis, for forming a circular groove which is concentric with the axis.
• the lithographic beam and the axis can then be controlled relative to each other to form a plurality of grooves which are concentric with the axis, each groove being exposed to essentially said predetermined degree of exposure, independently of the radial distance of the groove to the axis.
• a plurality of grooves with the same degree of exposure can be provided. This may take place in various ways.
• the number of exposures to which the groove is subjected may be a function of the radial distance of the groove to the axis.
• the intensity of the lithographic beam may be controlled so as to be a function of the radial distance of the groove to the axis. This results in a more accurate exposure, but requires that the intensity of the lithographic beam can be controlled.
• an angular speed at which the substrate is rotated may be a function of the radial distance of the groove to the axis. This results in a more accurate exposure and is usable if the intensity of the lithographic beam cannot be controlled.
• the groove may be subjected to continuous exposure to the lithographic beam, to form a continuous groove of exposed material, or to intermittent exposure to the lithographic beam, to form a groove consisting of a plurality of portions of exposed material which are wholly or partly separated in the direction of the tangent .
• the lithographic beam and the substrate may be controlled relative to each other to form an essentially spiral groove, at a varying radial distance from the axis.
• the lithographic beam and the substrate may be controlled relative to each other according to that described above for the purpose of forming a plurality of grooves or groove portions with essentially the same degree of exposure.
• a computer program product comprises instructions which during execution control a device, in which a lithographic beam forms a groove of a material, exposed to a predetermined degree, in a surface layer of an essentially flat substrate rotatable about an axis.
• the instructions of the computer program product are characterized in that they ensure that the lithographic beam and the axis, during rotation of the substrate about the axis, are controlled relative to each other so that part of the groove is subjected to more than one exposure to the lithographic beam, the groove being formed as a sum of said more than one exposure .
• the computer program product can be a memory medium which is suitable for the purpose and on which software and/or control instructions for controlling the lithographic device are stored and which, during execution, performs the method according to the invention.
• Examples of such storage media are diskettes, CD-ROMs, DVD- ROMs, hard disks etc. It is also conceivable to distribute the instructions via a computer network, such as the Internet .
• a device for lithography comprises a radiation source for generating a lithographic beam, a rotating means for supporting an essentially flat substrate rotatable on said rotating means, a positioning means for moving the lithographic beam and the substrate relative to each other, and a control means for controlling said lithographic beam, rotating means and positioning means.
• the device is characterized in that said control means, during rotation of the substrate on the rotating means, controls the lithographic beam and the rotating means relative to each other, so that part of the groove is subjected to more than one exposure to the lithographic beam, the groove being formed as a sum of said more than one exposure .
• said radiation source may be a particle source, preferably an ion source or an electron source.
• an electromagnetic source such as an X-ray source or a light source, may be used, although the radiation from this type of sources usually cannot be focused just as well as particle radiation.
• light source is meant, for instance, a point light source which is reproduced on the surface layer or a laser whose light is focused on the surface layer.
• the rotating means may be a device, on which the substrate is arranged to be rotated about a rotational axis with sufficient accuracy and at a sufficient speed.
• the positioning means may be a device for moving the lithographic beam relative to the substrate.
• the radiation source or the substrate may be displaced, or the beam may be controlled in prior-art manner by, for instance, deflection.
• the control means may be, for example, a prior-art numerical control system for generating signals to the positioning means and, optionally, also to the rotating means and/or the radiation source.
• Fig. 1 is a schematic perspective view of a first system with which the present invention can be implemented .
• Fig. 2 is a more detailed schematic top plan view of a substrate which can be obtained according to the present invention.
• Fig. 3 is a schematic top plan view of a first variant of a substrate according to the present invention.
• Fig. 4 is a schematic top plan view of a second variant of a substrate according to the present invention.
• Fig. 5 is a schematic top plan view of a third variant of a substrate according to the present invention.
• Fig. 6 is a schematic top plan view of a fourth variant of a substrate according to the present invention.
• Fig. 7 is a schematic cross-sectional view of a device for lithography, by means of which the present invention can be implemented. Description of Embodiments of the Invention
• Fig. 1 shows a system for forming essentially circular grooves in a surface layer of a rotatable medium, such as an optical or magnetic memory medium, or a template/stamp for making such memory media.
• a essentially flat substrate 3 is rotatably arranged about an axis 5.
• a surface layer 4 arranged on the substrate 3 may be essentially flat, i.e. sufficiently flat to be subjected to lithographic processing by means of a lithographic beam 2, for the purpose of making a groove 6 on the layer 3.
• the lithographic beam 2 may be emitted from a radiation source 1 and be an electron beam or ion beam. Other types of particle beams which are suited for lithography are also conceivable.
• an electromagnetic radiation source for instance an X-ray source or a light source
• an electromagnetic radiation source for instance an X-ray source or a light source
• light source is meant, for instance, a point light source which is reproduced on the surface layer or a laser whose light is focused on the surface layer.
• the surface layer 4 can be made of a material suitable for lithography, such as a positive or negative resist. It will also be appreciated that the substrate 3 can be provided with a plurality of wholly or partly overlapping surface layers, one of them haying such properties as to be influenced by the lithographic beam 2.
• the lithographic beam 2 falls on the surface layer of the substrate on a small spot only, whose cross-section essentially corresponds to the cross- section of the lithographic beam 2.
• the radiation source 1 and the substrate 3 are arranged in such a manner that the lithographic beam incident on the surface layer 4 of the substrate can be displaced in at least one direction across the surface layer 4 of the substrate. This may take place, for instance, by the radiation source or the substrate being displaced so that the lithographic beam incident on the surface layer 4 is moved along a radius on the rotatable substrate 3.
• the displacement of the lithographic beam can take place in a suitable prior-art manner by, for instance, physical movement of the radiation source 1, by physical displacement of the substrate 3, or by a combination thereof.
• the substrate 3 can be suspended from the axis .5 by means of a rotation bearing suitable for the pose, such as a high precision rotation bearing (not shown) , and be provided with a drive mechanism (not shown) .
• the system in Fig. 1 functions in such a manner that the surface layer 4 of the substrate in one spot is exposed to the lithographic beam 2 while the substrate is rotated about the axis 5. If the lithographic beam 2 is held at a constant distance from the center of rotation, a groove 6, concentric with the rotational axis, of exposed material will be formed in the surface layer 4 of the substrate.
• the surface layer 4 In lithography, the surface layer 4 must be exposed to a predetermined degree to allow the pattern to be developed. Development is performed by dissolving the exposed or unexposed parts of the surface layer, depending on whether the surface layer consists of a positive or negative resist. Then some type of aftertreatment , such as depositing a further layer or etching, may be carried out. Optionally, depositing may be carried out before developing, thereby producing hollow structures.
• the predetermined degree of exposure is, according to the invention, such that the desired aftertreatment of the surface layer 4 can take place.
• the groove 6 is formed by the surface layer 4 where the groove is desired is repeatedly exposed to the lithographic beam 2, each exposure giving a degree of exposure which is smaller than the predetermined degree of exposure which is necessary for the forming of the desired groove .
• this repeated exposure can be performed by the substrate 3 being rotated several turns about the axis 5 while at the same time the lithographic beam 2 is held at a constant distance from the center of rotation.
• the influence exerted by any slack or play associated with the mechanical suspension and rotation mechanism (not shown) can be reduced.
• the lithographic beam 2 being held in a fixed position.
• the predetermined degree of exposure is Q
• the deviation of each exposure will only contribute 10% to the total deviation while the "average area" of the exposures obtains essentially complete exposure corresponding to the predetermined degree of exposure .
• 100 exposures at a degree of exposure Q/100 are selected, where the deviation of each exposure contributes 1% to the total deviation. It will be appreciated that other numbers of exposures may be chosen and that the intensity of the lithographic beam may be varied within an exposure sequence .
• the number of exposures to which the groove is subjected may be a function of the radius of the groove .
• the intensity of the lithographic beam may be controlled so as to be a function of the radius of the groove.
• an angular speed at which the lithographic beam and the surface layer are controlled relative to each other may be a function of the radial distance of the groove to the axis 5.
• Fig. 2 is a more detailed schematic top plan view of a substrate which can be obtained according to the present invention.
• Fig. 2 shows specifically a groove 6 of exposed material, which has been formed by the lithographic beam 2 being moved relative to the substrate 3 on three occasions, so that three grooves 10, 11 and 12 of exposed material are formed.
• each of the three grooves 10, 11 and 12 deviates from the desirable groove 13.
• This deviation may be a result of, for instance, play in the rotation bearing or interference in the lithographic beam caused by ambient static electricity, magnetic fields or electric fields.
• the contribution from the deviation of each exposure however is smaller than in the case where only one exposure had been made, and therefore a groove 6 is obtained in the form of a sum of the three grooves 10, 11 and 12, which sum better approximates the desirable groove 13.
• Fig. 3 is a schematic top plan of a first variant of a substrate according to the present invention.
• a plurality of continuous grooves 6, which are concentric with the rotational axis of the substrate 3 have been formed in the surface layer 4 of the substrate according to one of the methods described above.
• Fig. 4 is a schematic top plan view of a second variant of a substrate according to the present invention.
• a plurality of non-continuous grooves 6, which are concentric with the rotational axis of the substrate (3) are formed in the surface layer 4 of the substrate according to one of the methods described above.
• the grooves 6 consist of a plurality of portions of exposed material which are wholly or partly separated in the direction of the tangent.
• These non- continuous grooves may be formed by being exposed intermittently, i.e. by the lithographic beam 2 being caused to fall on the surface layer in the form of pulses. This can be provided by the actual lithographic beam being pulsed or by a constant lithographic beam passing through a radiation valve.
• Fig. 5 is a schematic top plan view of a third variant of a substrate according to the present invention.
• a spiral, continuous groove 6 is formed in the surface layer 4 of the substrate according to one of the methods described above.
• This spiral groove can be formed by the surface layer 4 of the substrate being repeatedly exposed to the lithographic beam while the lithographic beam is displaced radially relative to the substrate 3, as illustrated in Fig. 1.
• the groove may be formed by deflection, as shown in Fig. 4. It will be appreciated that a plurality of spiral grooves can be formed on the surface layer of the substrate .
• Fig. 6 is a schematic top plan view of a fourth variant of a substrate according to the present invention.
• a spiral, non-continuous groove 6 is formed in the surface layer 4 of the substrate according to one of the methods described above. These grooves consist of a plurality of portions of exposed material which are wholly or partly separated in the direction of the tangent.
• Fig. 7 is a schematic cross-sectional view of a device for lithography, by means of which the present invention can be implemented.
• the device comprises a radiation source 1 of a desirable type, for instance a particle radiation source such as an ion source or an electron source, and the components that are required to produce a lithographic beam 2 which is suitable for the purpose.
• a radiation source 1 of a desirable type for instance a particle radiation source such as an ion source or an electron source, and the components that are required to produce a lithographic beam 2 which is suitable for the purpose.
• an electromagnetic radiation source such as an X-ray source or a light source, may be used even if the radiation from this type of sources normally cannot be focused just as well as particle radiation.
• light source is meant, for instance, a point light source which is reproduced on the surface layer or a laser whose light is focused on the surface layer.
• the device has a means 5 for rotationally supporting a substrate 3 with a surface layer 4 which is intended to be exposed to the lithographic beam 2.
• the rotating means 5 is to be arranged so as to be able to cause the substrate 3 to rotate with a minimum slack or play and at a well controllable speed.
• the rotating means has a rotatable body on which the substrate is arranged and is optionally fixed during the treatment .
• the rotating means 5 can be provided with an antifriction bearing suitable for the purpose and a drive mechanism for driving the rotation of the rotating means 5.
• the device comprises a positioning means 7 for positioning the radiation source 1 relative to the substrate 3.
• the positioning means 7 can be configured in various ways. For instance, as shown in Fig. 7, it may comprise a carriage 7 which is displaceable along a radius of the substrate, the radiation source 1 being fixedly arranged and the substrate 3 being displaced relative to the radiation source.
• the radiation source can be displaceable or rotatable and the rotating means 5 supporting the substrate can be fixedly arranged.
• the lithographic beam can be deflectable by means of a suitable field, such as a magnetic field or electric field (not shown) . Combinations of the above-mentioned different types of positioning means are also feasible.
• control means 14 which may be a control unit suitable for the purpose.
• a microcomputer (not shown) connected to suitable control loops (not shown) may be used for controlling one or more of the radiation source 1, the rotating means 5 and the positioning means 7.
• the control means may be provided with instructions controlling the device according to the method described above .
• the inventive method may also be implemented by means of a computer program product for controlling a lithography device.
• a computer program product may contain instructions by means of which the lithography device is controlled according to one of the methods above .

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• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Exposure And Positioning Against Photoresist Photosensitive Materials (AREA)
• Manufacturing Optical Record Carriers (AREA)
• Moulds For Moulding Plastics Or The Like (AREA)
• Shaping Of Tube Ends By Bending Or Straightening (AREA)

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• 2003
  • 2003-04-24 AU AU2003224565A patent/AU2003224565A1/en not_active Abandoned
  • 2003-04-24 WO PCT/SE2003/000654 patent/WO2003091805A1/en not_active Ceased
  • 2003-04-24 CN CNB03809147XA patent/CN1313884C/zh not_active Expired - Fee Related
  • 2003-04-24 EP EP03721234A patent/EP1497698A1/en not_active Withdrawn
  • 2003-04-24 US US10/512,274 patent/US7468784B2/en not_active Expired - Lifetime
  • 2003-04-24 JP JP2004500121A patent/JP2005524104A/ja active Pending
• 2010
  • 2010-11-02 JP JP2010246532A patent/JP5248574B2/ja not_active Expired - Lifetime

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