US3905883A - Electrolytic etching method - Google Patents

Electrolytic etching method Download PDF

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US3905883A
US3905883A US480472A US48047274A US3905883A US 3905883 A US3905883 A US 3905883A US 480472 A US480472 A US 480472A US 48047274 A US48047274 A US 48047274A US 3905883 A US3905883 A US 3905883A
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etched
potential
mol
anode electrode
electrolytic etching
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US480472A
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Masanobu Hanazono
Osamu Asai
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Hitachi Ltd
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Hitachi Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
    • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
    • H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
    • H01L21/31—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to form insulating layers thereon, e.g. for masking or by using photolithographic techniques; After treatment of these layers; Selection of materials for these layers
    • H01L21/3205—Deposition of non-insulating-, e.g. conductive- or resistive-, layers on insulating layers; After-treatment of these layers
    • H01L21/321—After treatment
    • H01L21/3213—Physical or chemical etching of the layers, e.g. to produce a patterned layer from a pre-deposited extensive layer
    • H01L21/32133—Physical or chemical etching of the layers, e.g. to produce a patterned layer from a pre-deposited extensive layer by chemical means only
    • H01L21/32134—Physical or chemical etching of the layers, e.g. to produce a patterned layer from a pre-deposited extensive layer by chemical means only by liquid etching only
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25F—PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
    • C25F3/00—Electrolytic etching or polishing
    • C25F3/02—Etching
    • C25F3/14—Etching locally
    • 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
    • G11B5/127—Structure or manufacture of heads, e.g. inductive
    • G11B5/31—Structure or manufacture of heads, e.g. inductive using thin films
    • G11B5/3163—Fabrication methods or processes specially adapted for a particular head structure, e.g. using base layers for electroplating, using functional layers for masking, using energy or particle beams for shaping the structure or modifying the properties of the basic layers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
    • H01F41/14—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for applying magnetic films to substrates
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof

Definitions

  • a precise pattern figure can be formed on a thin film of permalloy, iron, nickel, cobalt and copper through an electrolysis with a mixture of ammonium persulfate and nitric acid electrolyte under control of the electrode potential.
  • a desired part of an electrode whose surface is in coexistence with aluminum can be electrolytically etched without damaging the aluminum.
  • the present invention relates to an electrolytic etching method available for preparation of large size integrated circuits incorporated with a number of highly concentrated elements and circuits formed on a substrate, formation of electrodes of semiconductor elements and preparation of other elements and circuit: as well.
  • a mask pattern of photoresist can have highly precise dimension and therefore with photoresist it is possible to form a mask pattern with l ,um precision.
  • precision in a completed pattern is reduced to about um on account of the irregularity of etching and the damage of the photoresist mask.
  • the chemical etching it is usual to raise the temperature for the purpose of promoting the dissolving speed and this often damages the photoresist film.
  • an electrolytic etching softly acts on an object to be etched.
  • electrolysis creates gases which are liable to cause the photoresist film to be peeled off, thus degrading precision in the pattern.
  • a so-called selective electrolytic etching method wherein only one of two kinds of metals electrically connected and exposed from the electrode surface is dissolved has not been used for forming thin film circuit patterns since it requires a special combination of different metals and special conditions.
  • a principal object of the present invention is to provide an electrolytic etching method for forming a precise pattern figure on thin films of permalloy, iron, nickel, cobalt, copper and molybdenum.
  • a second object of the present invention is to provide an electrolytic etching method wherein a metal thin film a part of which is coated with a photoresist pattern film can be etched without damaging the photoresist pattern film.
  • a third object of the present invention is to provide a selective electrolytic etching method wherein permalloy, iron, nickel, cobalt, copper, and molybdenum are each electrically connected to aluminum and under this electrical connection the permalloy, iron, nickel, cobalt, copper or molybdenum is selectively dissolved.
  • a fourth object of the present invention is to provide an electrolytic etching method capable of suppressing the creation of gases.
  • a fifth object of the present invention is to provide an electrolytic etching method wherein etching performance of metals can be observed during the etching process.
  • a sixth object of the present invention is to provide measures of preparing precise electronic parts such as an aluminum strip lead and thin film magnetic heads.
  • FIG. 1 is a schematic representation of one type of electrolytic etching device embodying the invention.
  • FIG. 2 is a graphic representation of etching pattern figures in accordance with different electrolytes and materials of a pattern mask.
  • FIGS. 3a to 3d show photographs of etched permalloy films provided on a glass substrate.
  • FIG. 4 is a diagramatic representation of preparing process of a strip lead to which the invention is applied.
  • FIG. 5 is a perspective view of a thin film magnetic head.
  • the present invention contemplates a method of electrolytic etching with a mixture of ammonium persulfate and nitric acid electrolyte for dissolving permalloys as well as iron, nickel, cobalt, copper and alloys thereof.
  • an electrolytic etching method wherein an electro-chemical action is intentionally applied to an etching reaction. It also involves a case where some electro-cl'nemical means are added for promoting, or sometimes suppressing, the chemical etching reaction.
  • the electro-chemical means is identical to means for changing electrode potential of an object to be etched from the natural electrode potential, which the object bears when immersed alone in an electrolyte, to a desired potential, and it may be constituted, for example, by application of voltage with an external power source or coupling of the object to be etched with a different metal].
  • the electrolyte used herein is an aqueous solution which contains 0.1 to 2.5 mol/l ammonium persulfate [(NH S O and 0.2 to 10 mol/l nitric acid.
  • the dissolving speed of permalloy is caused to differ markedly dependent on compositions of the permalloy and preparing conditions therefor. For example, since the dis solving speed of a vacuum evaporation deposited film is less than that of casting material and plated material by 1/10 to l/lOO, the aqueous solution of ammonium persulfate alone is unsuitable for electrolyte for making an etching pattern of an object coexistent with the casting and plating materials.
  • the electrolyte of ammonium persulfate aqueous solution has a comparatively small etching speed and it will tend to damage anti-etching photoresist films.
  • copper and cobalt-vanadium-iron alloy bear dissolving speeds of about 0.2 pun/min and l um/min, respectively, while the photoresist film of about 2 pm thickness can assume the protective ability within about 10 minutes. Accordingly, with the anti-etching photoresist film the depth of etching is restricted to less than 2 mm for copper and within um even for irons.
  • the electrolytic etching speed is markedly increased owing to the oxidization action of nitric acid and especially difference in the dissolving speed clue to different preparation processes such as plating or evaporation becomes almost negligible.
  • the addition of nitric acid acts to reduce the polarization of an iron object and to increase the passivating range of aluminum
  • the ammonium persulfate aqueous solution added with nitric acid is advantageous to such a selective etching as to etch only the iron and copper of metals coexisting with aluminum.
  • nitric acid ferric chloride, cupric chloride, potassium bichromate, and cerium sulfate are useful as oxidizing acids adapted to be added to the ammonium persulfate.
  • chlorides induce etch pits on an aluminum surface, other additional substances than chlorides should be used when it is necessary to avoid the etch pits on the aluminum surface.
  • supplemental injection of oxygen gas and addition of hydrogen peroxide are effective.
  • concentration of ammonium persulfate within the electrolyte is 0.1 to 2.5 mol/l but 0.8 to 1.5 mol/l is preferred to the practical use, at which the solution assumes pl-l representation of 1.8 to 1.9.
  • the oxygen creation potential (relative to saturated caromel electrode, hereinafter abbreviated as SCE) is about 1.0 volt.
  • SCE saturated caromel electrode
  • the electrode potential at the permalloy electrode adapted to be dissolved can be decreased below the oxygen creation potential, particularly below 1.0 volt (relative to SCE), thereby enabling etching of the permalloy without causing the creation of oxygen gas.
  • the electrode potential at permalloy object to be etched may be selected to -0.1 to 0.5 volts (relative to SCE).
  • the 1 mol/l concentration ammonium persulfate electrolyte, aluminum is passivated over a wide range of the oxygen creation potential of 0.5 to 2.5 volts (relative to SCE). When added with nitric acid, however, the passivation becomes unstable and the etch pit potential is observed.
  • the etch pit potential decreases, especially, at the nitric acid concentration of above 10 mol/l a current flow necessary for maintaining the passivation exceeds 1 mA/cm Accordingly, it will be seen that the additional amount of the nitric acid ranges from 0.2 to 10 ml/l to obtain an aluminum etch pit potential of above 1.7 volts (relative to SCE) and the current flow necessary for passivation of below 0.5 mA/cm Preferably it ranges from 0.5 to 8 mol/l.
  • a rapid etching for magnetic objects such as iron, nickel and cobalt and alloys thereof as well can be achieved with an electrolyte which contains 0.1 to 2.5 mol/l concentration ammonium persulfate and 0.2 to 10 mol/l nitric acid under the application of a potential between the natural electrode potential and the oxygen creation potential to the object.
  • an electrolyte which contains 0.1 to 2.5 mol/l concentration ammonium persulfate and 0.2 to 10 mol/l nitric acid under the application of a potential between the natural electrode potential and the oxygen creation potential to the object.
  • gas evolution is avoided, and it leads to the prevention of the photoresist film from being peeled off, and so aluminum will not be damaged.
  • the aluminum is maintained in the passivation range, so it will not be dissolved.
  • EXAMPLE 1 A permalloy sheet of 30 um thickness provided with a precise mask pattern was subjected to an electrolytic etching to examine the respective preferable kinds of mask material and electrolyte from the etching figure.
  • FIG. 1 designates a permalloy sample to be etched, which sample constitutes an anode electrode.
  • Numeral 2 designates a platinum cathode electrode in the form of a plate, which cathode electrode 2 is separated by an unglazed tube 5 such that gas created therein is prevented to prevail into the electrolyte but is electrically communicated with the etching electrolyte through the unglazed tube 5.
  • Numeral 3 disignates a glass capillary vessel for measuring the electrode potential.
  • electrolyte 4 there are further provided electrolyte 4, an electrolytic bath 6, a gas injection pipe 7 through which gas is injected into electrolyte with need to control the circumferential conditions thereof a magnetic stirrer 8 and a stirrer piece 9 adapted for stirring the electrolyte, saturated KNO solution 10, a salt bridge 1 1, saturated KCl solution 12, a saturated calomel electrode 1-3 and a potentiostat 14 for measuring the anode potential relative to the saturated calomel electrode and maintaining the anode potential at a desired value.
  • the electrolitic etching in accordance with the present invention was carried out by maintaining the anode electrode potential and the oxygen creation potential of the permalloy sample to be etched with a DC. voltage being applied between the platinum cathode elec trode and the anode electrode of the permalloy sample.
  • Table l permalloy compositions of the sample to be etched.
  • permalloy film was coated with a photoresist film of a commercial photoresist made of isobutylene rubber and polycinnamic vinyle and deposited with aluminum by evaporation, with an uncovered partial figure of i 1 pm width and 50 um length.
  • a photoresist film of a commercial photoresist made of isobutylene rubber and polycinnamic vinyle was deposited with aluminum by evaporation, with an uncovered partial figure of i 1 pm width and 50 um length.
  • Three kinds of electrolytes as listed in Table 2 were used. With a 30C temperature electrolyte and under 0.1 volts (relative to SCE) electrode potential, the etching was performed to measure relation between the depth and the width of etched slots.
  • Results are illustrated in FIG. 2.
  • symbol A represents a case where No. 2 electrolyte is used with the protective coating of aluminum evaporation deposition, wherein a sharp slot is formed having the smallest extension in the width direction.
  • symbol B represents a case where No. 2 and No. 3 electrolytes are used with the protective coating of photoresist
  • symbol C represents a case where No. l electrolyte is used with a photoresist film.
  • Symbol D represents a case where No. 2 electrolyte is used with a photoresist film, wherein a chemical etching is performed without passing a current flow. In chemical etching the etching speed was less than one-half that of the electrolytic etching and the dissolved or etched depth remarkably differs in the direction of width.
  • EXAMPLE 2 Permalloy was deposited by means of evaporation upon a glass substrate (No. 7059 glass substrate of Cor ning) to a thickness of about 3,000 A and thereupon a permalloy layer was plated to a thickness of um.
  • Photoresist film (KMER) was used as the protective mask and an electrolytic etching was performed under a constant potential of 0.05 volts (relative to SCE). After the etching, etched pattern figures were photographed as shown in FIG. 3.
  • FIGS. 1 Photoresist film
  • 3a to 3d correspond to electrolytic etchings with 1 mol/l ammonium persulfate electrolyte, 1 mol/l ammonium persulfate and 0.1 mol/l nitric acid electrolyte, 1 mol/l ammonium persulfate and 0.5 mole/l nitric acid electrolyte, and l mol/l ammonium persulfate and 1 mol/l nitric acid electrolyte, respectively.
  • the electrolytic etching corresponding to FIG.
  • EXAMPLE 3 On a glass substrate, a copper evaporation deposition pattern was formed and thereon a nickel plating layer was placed by about pm thick, thereby to form a multiple-layer as shown in FIG. 4a.
  • a glass substrate 1, a copper evaporation deposition layer 2 and a nickel plating layer 3 are illustrated in the figure.
  • the multiple-layer was subjected to a shadowing evaporation with aluminum at 30 incident angle to obtain a resulted structure as illustrated in FIG. 4b. Thereafter, the resulted structure was electrolytically etched in 1.5 moI/l ammonium persulfate 1.5 mol/l nitric acid electrolyte under a constant electrode potential of zero volt (relative to SCE).
  • an aluminum beam lead which takes a shape as shown in FIG. 4c was prepared.
  • EXAMPLE 4 In manufacturing process of a thin-film magnetic head for writing in and reading out recording signals of a magnetic recording medium, a precise finish of figure is required for increasing recording density.
  • a ferrite substrate 1 on which aluminum conductors 2 having an anodic coating on their surfaces are placed, and an upper permalloy magnetic member 3 across the aluminum conductors 2 magnetically communicating with the ferrite substrate 1 at its rear portion.
  • a magnetic gap between the ferrite substrate and the front portion of an upper magnetic member serves as a magnetic head.
  • the width d of the upper permalloy magnetic member equals the track width and therefore the upper permalloy magnetic member is required to be formed with high accuracy.
  • a permalloy thin film layer having a larger area than a desired figure and 20 pm thickness was formed by means of the evaporation and plating, and thereupon a precise pattern of the desired figure was formed with naphthoquinone-diazo positive type photoresist coating.
  • a resulted structure was subjected to an electrolytic etching in 1 mol/l ammonium persulfate-2 mol/l nitric acid electrolyte under a constant potential of 0.2 volts (relative to SCE), thereby to obtain the upper permalloy magnetic member. Errors in the width of the upper permalloy magnetic member thus obtained were within 30 m )i 15 am for one side) with respect to a target width of 200 pm.
  • an electrolytic etching method of the invention it is possible to form precisely figured etching patterns and further it is possible to form comparatively readily a desired pattern figure on an object to be etched, with partly unetched portions if the etching intensity has previously been measured. Easy washing after completion of electrolyte etching and mass-treatment of fine and sophisticated objects to be etched within a short time permit a readily available etching method.
  • An electrolytic etching method for etching precise electrical parts wherein a 0.1 to 2.5 mol/l concentration ammonium persulfate 0.02 to 10 mol/l concentration nitric acid electrolyte is used and a DC voltage is applied between a cathode electrode of insoluble metal and an anode electrode including a metal object to be etched, said metal object being made from a member selected from the group consisting of iron, nickel, cobalt, copper and alloys thereof, whereby a constant potential electrolytic etching is performed by maintaining the anode electrode potential between the natural electrode potential and the oxygen creation potential of said objects to be etched.
  • electrolytic etching method comprises a 0.8 to 1.5 mol/l concentration ammonium persulfate 0.5 to 8 mol/l concentration nitric acid solution.
  • An electrolytic etching method according to claim 1, wherein said anode electrode including said metal objects to be etched is covered with isobutylene rubber, polycinamic vinyle, diazo compound photoresist films at a part other than that to be etched.
  • An electrolytic etching method according to claim 1, wherein said anode electrode including said metal objects to be etched is covered with an aluminum film at a part other than that to be etched.
  • An electrolytic etching method for etching precise electrical parts wherein one end of an anode electrode including an object to be etched is connected to a potentiostat, said object being constituted by an electrically insulative substrate or aluminum layer provided thereon with a thin film made from a member selected from the group consisting of iron, nickel, cobalt and alloys thereof said thin film being coated with a photoresist or aluminum pattern, one end of a cathode electrode including an insoluble metal is connected to said potentiostat, and the other ends of said anode electrode and said cathode electrode are immersed in a 0.8 to 1.5 mol/l concentration ammonium persulfate 0.5 to 8 mol/l nitric acid electrolyte, whereby a constant potential electrolytic etching is performed by maintaining the anode electrode potential between the natural electrode potential and the oxygen creation potential of said anode electrode.
  • An electrolytic etching method wherein after a constant potential electrolysis is performed by maintaining the anode electrode potential between the natural electrode potential of said anode metal and 1.2 volts (relative to SCE), a noble potential than said natural electrode potential is applied to said anode electrode immersed in said electrolyte, whereby a remaining part of metal to be etched which has been electrically insulated is dissolved.
  • An electrolytic etching method according to claim 1, wherein said anode electrode including a metal object to be etched comprises aluminum.

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Cited By (15)

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US4543153A (en) * 1984-05-17 1985-09-24 Psi Star Process and apparatus for etching copper masked by a nickel-gold mask
EP0658220A4 (en) * 1990-10-31 1993-07-23 Omri M Behr METHOD AND DEVICE FOR PRODUCING ETCHING PLATES FOR GRAPHIC PRINTING.
US5248386A (en) * 1991-02-08 1993-09-28 Aluminum Company Of America Milling solution and method
US5509556A (en) * 1994-11-17 1996-04-23 International Business Machines Corporation Process for forming apertures in a metallic sheet
US20010031549A1 (en) * 1999-11-23 2001-10-18 Crawford Ankur Mohan Magnetic layer processing
US20030001713A1 (en) * 1999-11-23 2003-01-02 Gardner Donald S. Integrated transformer
US20030005572A1 (en) * 1999-11-23 2003-01-09 Gardner Donald S. Integrated inductor
US20040157370A1 (en) * 1999-11-23 2004-08-12 Intel Corporation Inductors for integrated circuits, integrated circuit components, and integrated circuit packages
US20040222492A1 (en) * 2003-05-05 2004-11-11 Gardner Donald S. On-die micro-transformer structures with magnetic materials
US20050017837A1 (en) * 1999-11-23 2005-01-27 Gardner Donald S. Integrated transformer
US20050082257A1 (en) * 2001-09-10 2005-04-21 Gust Bierings Method of etching copper on cards
US20070001762A1 (en) * 2005-06-30 2007-01-04 Gerhard Schrom DC-DC converter switching transistor current measurement technique
US20140269228A1 (en) * 2013-03-14 2014-09-18 Seiko Instruments Inc. Metal structure, method of manufacturing metal structure, spring component, chronograph coupling lever for timepiece, and timepiece
US20160053399A1 (en) * 2014-08-25 2016-02-25 Seiko Epson Corporation Forming method and formed article
US11738927B2 (en) 2018-06-21 2023-08-29 First Quality Tissue, Llc Bundled product and system and method for forming the same

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Cited By (48)

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EP0658220A4 (en) * 1990-10-31 1993-07-23 Omri M Behr METHOD AND DEVICE FOR PRODUCING ETCHING PLATES FOR GRAPHIC PRINTING.
US5248386A (en) * 1991-02-08 1993-09-28 Aluminum Company Of America Milling solution and method
US5509556A (en) * 1994-11-17 1996-04-23 International Business Machines Corporation Process for forming apertures in a metallic sheet
US20060163695A1 (en) * 1999-11-23 2006-07-27 Intel Corporation Inductors for integrated circuits
US20030001713A1 (en) * 1999-11-23 2003-01-02 Gardner Donald S. Integrated transformer
US20030005572A1 (en) * 1999-11-23 2003-01-09 Gardner Donald S. Integrated inductor
US20040046630A1 (en) * 1999-11-23 2004-03-11 Gardner Donald S. Integrated transformer
US20040157370A1 (en) * 1999-11-23 2004-08-12 Intel Corporation Inductors for integrated circuits, integrated circuit components, and integrated circuit packages
US6815220B2 (en) * 1999-11-23 2004-11-09 Intel Corporation Magnetic layer processing
US7982574B2 (en) 1999-11-23 2011-07-19 Intel Corporation Integrated transformer
US20040250411A1 (en) * 1999-11-23 2004-12-16 Gardner Donald S. Integrated inductor
US20050017837A1 (en) * 1999-11-23 2005-01-27 Gardner Donald S. Integrated transformer
US6856228B2 (en) 1999-11-23 2005-02-15 Intel Corporation Integrated inductor
US6856226B2 (en) 1999-11-23 2005-02-15 Intel Corporation Integrated transformer
US6870456B2 (en) 1999-11-23 2005-03-22 Intel Corporation Integrated transformer
US20050062575A1 (en) * 1999-11-23 2005-03-24 Gardner Donald S. Integrated transformer
US20100295649A1 (en) * 1999-11-23 2010-11-25 Gardner Donald S Integrated transformer
US6891461B2 (en) 1999-11-23 2005-05-10 Intel Corporation Integrated transformer
US20050146411A1 (en) * 1999-11-23 2005-07-07 Gardner Donald S. Integrated inductor
US6940147B2 (en) * 1999-11-23 2005-09-06 Intel Corporation Integrated inductor having magnetic layer
US6943658B2 (en) 1999-11-23 2005-09-13 Intel Corporation Integrated transformer
US6988307B2 (en) 1999-11-23 2006-01-24 Intel Corporation Method of making an integrated inductor
US7064646B2 (en) 1999-11-23 2006-06-20 Intel Corporation Integrated inductor
US7119650B2 (en) 1999-11-23 2006-10-10 Intel Corporation Integrated transformer
US20010031549A1 (en) * 1999-11-23 2001-10-18 Crawford Ankur Mohan Magnetic layer processing
US7087976B2 (en) 1999-11-23 2006-08-08 Intel Corporation Inductors for integrated circuits
US7791447B2 (en) 1999-11-23 2010-09-07 Intel Corporation Integrated transformer
US7299537B2 (en) 1999-11-23 2007-11-27 Intel Corporation Method of making an integrated inductor
US7327010B2 (en) 1999-11-23 2008-02-05 Intel Corporation Inductors for integrated circuits
US7332792B2 (en) * 1999-11-23 2008-02-19 Intel Corporation Magnetic layer processing
US7434306B2 (en) 1999-11-23 2008-10-14 Intel Corporation Integrated transformer
US20090015363A1 (en) * 1999-11-23 2009-01-15 Gardner Donald S Integrated transformer
US20050082257A1 (en) * 2001-09-10 2005-04-21 Gust Bierings Method of etching copper on cards
US7767074B2 (en) * 2001-09-10 2010-08-03 Obducat Ab Method of etching copper on cards
US20040222492A1 (en) * 2003-05-05 2004-11-11 Gardner Donald S. On-die micro-transformer structures with magnetic materials
US8471667B2 (en) 2003-05-05 2013-06-25 Intel Corporation On-die micro-transformer structures with magnetic materials
US7852185B2 (en) 2003-05-05 2010-12-14 Intel Corporation On-die micro-transformer structures with magnetic materials
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JPS5313177B2 (enrdf_load_stackoverflow) 1978-05-08

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