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WO2002024977A1 - Procede de gravure par voie humide - Google Patents

Procede de gravure par voie humide Download PDF

Info

Publication number
WO2002024977A1
WO2002024977A1 PCT/SE2001/002012 SE0102012W WO0224977A1 WO 2002024977 A1 WO2002024977 A1 WO 2002024977A1 SE 0102012 W SE0102012 W SE 0102012W WO 0224977 A1 WO0224977 A1 WO 0224977A1
Authority
WO
WIPO (PCT)
Prior art keywords
substrate
etching
etch
protecting
etchant
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/SE2001/002012
Other languages
English (en)
Inventor
Bjarni Bjarnason
Per Pettersson
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Obducat AB
Original Assignee
Obducat AB
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from SE0003345A external-priority patent/SE517275C2/sv
Application filed by Obducat AB filed Critical Obducat AB
Priority to JP2002529567A priority Critical patent/JP4766823B2/ja
Priority to AU2001290424A priority patent/AU2001290424A1/en
Publication of WO2002024977A1 publication Critical patent/WO2002024977A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/02—Apparatus or processes for manufacturing printed circuits in which the conductive material is applied to the surface of the insulating support and is thereafter removed from such areas of the surface which are not intended for current conducting or shielding
    • H05K3/06—Apparatus or processes for manufacturing printed circuits in which the conductive material is applied to the surface of the insulating support and is thereafter removed from such areas of the surface which are not intended for current conducting or shielding the conductive material being removed chemically or electrolytically, e.g. by photo-etch process
    • H05K3/067—Etchants
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
    • C23F1/00—Etching metallic material by chemical means
    • C23F1/02—Local etching
    • 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

Definitions

  • the invention relates generally to etching of a substrate to produce small structures in the same. More specifically, the invention relates to a method of providing anisotropy in material-dissolving etching.
  • Micro- and nanostructures can be produced in a substrate by etching away selected parts of the surface of the substrate. These parts of the surface of the substrate are contacted with an etchant which is capable of reacting in an etching manner with the substrate material.
  • the substrate is before etching coated with a layer of etch- protecting material (resist) which reacts slowly, if at all, with the etchant.
  • the etch-protecting layer is often produced in a multistage process comprising a coating step, in which the etch-protecting material is applied over the entire substrate surface, and an exposing step, in which a pattern of exposed portions is produced in the etch-protecting material applied to the substrate.
  • the exposing step can be accomplished by the applied etch-protecting material (photo resist) being radiated through a mask and subsequently developed for exposing of either the radiated or unradiated portions thereof.
  • the material-dissolving etching methods can be divided into wet and dry techniques.
  • wet material -dissolving etching methods a liquid etchant is used.
  • chemical wet etching the etchant reacts spontaneously with the substrate material, and in electrochemical wet etching the etchant reacts by electrochemical reactions at the surface of the substrate material when the etchant, with applied voltage, carries a current .
  • the material -dissolving surface reactions which are intended to occur merely on the exposed portions of the substrate also have a certain tendency to occur in the periphery of the exposed portions, and also under the etch-protecting layer, and thus give rise to so-called underetching.
  • underetch- ing restricts the possibilities of producing narrow and deep structures, e.g. to arrange conductors close to each other.
  • US-A-5, 279, 702 discloses a technique for chemical wet etching of a substrate.
  • the substrate which is coated with a patterned resist layer, is immersed in a spontaneously etching etchant.
  • This etchant contains a passivating substance which spontaneously forms an etch- protecting compound on the exposed portions of the substrate, whereby these portions become unreactive to the etchant.
  • the etch-protecting compound is removed in the direction of the radiation so that etching can proceed in exposed portions of the substrate.
  • the etch-protecting compound prevents continued etching at the periphery of the exposed portions, which is protected from radiation by the superposed etch-protecting layer.
  • a barrier thus forms on the side walls of the etching structure, thereby minimizing underetching .
  • an object of the invention is to provide an improved method in wet etching, which obviates the above drawbacks of prior-art technique.
  • the inventive method is based on the understanding that a passivating substance, which during etching forms an etch-protecting compound, is to be arranged in the immediate vicinity of, but not on top of, the portions that are to be etched away.
  • the passivating substance is thus arranged on the substrate to define the pattern which is to be etched in the same.
  • the passivating substance is made to form an etch-protecting compound which defines said pattern on the substrate, whereby thus a barrier of the etch-protecting compound automa- tically is formed on the side walls of the structure and prevents underetching.
  • An etch-protecting layer is usually applied to the substrate before etching. It is preferred for the etch- protecting layer to be applied to the substrate in said pattern to define at least one exposed portion of the substrate, and for the passivating substance to be arranged at the periphery of the exposed portion so that the etch-protecting compound exclusively forms at this periphery. This is provided, according to a preferred embodiment, by the passivating substance being incorporated into the etch-protecting material which is later applied to the substrate to form the etch-protecting layer. This means that the passivating substance is automatically located in the periphery of the exposed portion of the substrate in connection with the forming of the pattern in the etch-protecting layer. During the etching procedure, the passivating substance, or an active substance thereof, leaks out of the etch-protecting layer and forms the etch-protecting compound at the periphery of the exposed portion of the substrate.
  • the etch-protecting layer is essentially an organic material .
  • At least one release layer containing the passivating substance is applied to the substrate before the etch-protecting layer forms thereon.
  • the release layer can thus be given a composition and a thickness which cause a desired local concentration of the passivating substance, or an active substance thereof, at the periphery of the exposed portion.
  • the release layer essentially consists of an organic material .
  • the etchprotecting compound is thus according to the present invention produced by an ion reaction.
  • a major advantage with the method according to the present invention is that the choice of ions may be varied within a wide range due to the fact that the component, which is to react with the active substance of the passivating substance, not has to be an etchant but may be freely chosen so as to achieve a good etchprotecting layer.
  • the passivating substance is preferably contained in an organic material, either in an etch- protective layer or in a release layer.
  • Figs 1-3 are part-sectional views of a substrate to illustrate a method in etching according to a first embodiment of the invention
  • Fig. 4 is a part-sectional view of a substrate to illustrate a method in etching according to a second embodiment of the invention. Description of the Embodiments of the Invention
  • Fig. 1 shows a part of a substrate 1 which is to be etched.
  • an etch-protecting material e.g. a photoresist
  • the etchprotecting layer 2 serves to protect the underlying substrate 1 against etching.
  • selected portions of the etch-protecting layer 2 are removed in a manner known per se, so that the substrate 1 is exposed in a given pattern, as is evident from Fig. 2.
  • the thus-exposed portions 3 of the substrate 1 are then allowed to react with an etchant 4 in a subsequent etching step, as shown in Fig. 3.
  • the etchant 4 is applied in the form of an electrolyte, which is forced electrochemically and/or chemically to etch the substrate 1.
  • the electrolyte 4 usually comprises a neutral salt which is not capable of reacting in an etching manner with the substrate 1, or an acid or a base.
  • the electrolyte 4 can also contain a chemically oxidating component which in itself is capable of reacting in an etching manner with the substrate 1.
  • the electrolyte 4 contains a relatively high content of such a chemically oxidating component.
  • a passivating substance (not shown) is contained in the etch-protecting layer 2.
  • This passivating substance forms during the etching step an etch-protecting compound on the substrate 1.
  • the passivating substance or an active substance thereof leaves the etch-protecting layer 2, as indicated by arrows A in Fig. 3, in order to form, with a component positioned adjacent to the substrate 1, an etch-protecting compound which is difficult to dissolve or unsoluble.
  • This compound settles on the periphery of the exposed portion 3 and forms a local barrier 5 against continued etching.
  • the barrier 5 comprises at least a monolayer of the etch-protecting compound in physical contact with the substrate 1.
  • a gradual and spontaneous composition of the barrier 5 occurs on the side walls 6 of the structure forming in the substrate.
  • the composition of the barrier 5 occurs essentially in a self-regulating process. If the etchant 4 tends to dissolve the substrate 1 also under the etchprotecting layer 2, the exposed surface of the etchprotecting layer 2 to the etchant 4 will increase, and the passivating substance, or its active substance, will to an increased extent leave the etch-protecting layer 2 and react with the above-mentioned component. Consequently also the forming of the etch-protecting compound increases .
  • the degree of barrier effect at the periphery of the exposed portion 3 of the substrate 1 can be controlled by, for example, changing the amount of the passivating substance contained in the etch-protecting material, or the thickness of the etch-protecting layer 2. It may also be advantageous to restrict the amount of the passivating substance contained in the etch-protecting mate- rial, so that the exposing step can be carried out by conventional methods, such as exposure and development.
  • the substrate 1 is made of metal, typically Cu, Cr, Ag, Au, Ni , or an alloy.
  • an etch-protecting layer 2 which is formed of an organic etch-protecting material, such as a liquid photoresist.
  • This passivating substance is in this case typically an ion compound which contains inorganic anions, such as I “ , F “ , Cl “ , Br “ , S 2” , SCN “ , CN “ , S0 4 2” , C 2 0 4 2” , P0 4 3" , C0 3 2 or Cr0 4 2 , and which can be admixed with the organic etch-protecting material.
  • the passivating substance is a compound, such as thioacetamide, which in another manner can be converted to a suitable anion.
  • the passivating substance is suitably selected so that it, or its active substance, e.g. its anion, in reaction with a component positioned adjacent to the substrate 1, forms the compound which is difficult to dissolve and which settles on the substrate 1.
  • This component can be cations which are released from the metallic substrate 1 during etching, or a cation which is included, naturally or as an additive, in the etchant 4.
  • the latter case allows use of a given passivating substance when etching different types of substrate material, since the passivating substance need not cooperate with the substrate material to form the etch-protecting compound.
  • etching of a substrate 1 of copper, or a copper alloy As an example, mention can be made of etching of a substrate 1 of copper, or a copper alloy. According to a conceivable alternative, use is made of a passivating substance containing iodide as an active substance, e.g. tetrabutyl ammonium iodide. During the etching step, iodide ions leave the etch-protecting layer 2 and react with copper ions, which are released from the substrate
  • chloride ions as an active substance, which after leaving the etch-protecting layer
  • etchprotecting silver chloride (AgCl) which settles on the periphery of the exposed portions 3 of the substrate 1.
  • etch-protecting compound instead of an anion, from the passivating substance can act as an active substance and form the compound which is difficult to dissolve, by reaction with the component positioned adjacent to the substrate.
  • Other compounds than ion compounds can also be used if they are soluble in the etch-protecting material, e.g. organic compounds capable of complexing, directly or via an active substance, the component at the substrate, for instance an anion or a cation.
  • Fig. 4 shows an alternative embodiment of the invention.
  • first one or more release layers 7 containing the passivating substance are applied to the substrate 1.
  • the release layer 7 is preferably thin and applied directly to the substrate 1.
  • a thickness of about 50-1000 nm has been found to give satisfactory results. However, also other thicknesses may be used.
  • an etch-protecting material preferably free from the passivating substance, is applied in an etch-protecting layer 2 on the release layer 7, whereupon selected portions of the etch-protecting layer 2 and the release layer 7 are removed in an exposing step, in a manner known per se, so that the substrate 1 is exposed in a given pattern, as is evident from Fig. 4.
  • the passivating substance, or an active substance thereof will locally leave the release layer 7 and form the etch-protecting barrier 5 at the periphery of the exposed portion 3 of the substrate 1. Since the release layer 7 can be arranged with an optional thickness and an optional amount of the passivating substance, the release of the passivating substance, or its active substance, at the periphery of the exposed portion 3 can be guided to optimized values.
  • This embodiment allows, in addition to the advantages of the method according to the first embodiment, a further optimization of the protection against underetching. Moreover this embodiment allows greater freedom in the choice of the passivating substance since this need not be soluble in the etch-protecting layer 2.
  • an extra exposing step such as plasma etching, may possibly be necessary before the etching step in order to completely expose the substrate 1 according to a defined pattern.
  • the active component of the passivating substance may alternatively be a cation.
  • the component is suitably an anion.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Electrochemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • General Chemical & Material Sciences (AREA)
  • Mechanical Engineering (AREA)
  • ing And Chemical Polishing (AREA)
  • Weting (AREA)

Abstract

L'invention concerne un procédé de gravure, selon lequel un agent d'attaque chimique (4), destiné à la gravure d'un substrat (1), est appliqué selon un motif donné. Avant la gravure, une couche de réserve (2) est appliquée sur le substrat (1) selon ce motif pour définir au moins une partie exposée (3) du substrat (1). Pour réduire au minimum la gravure sous-jacente pendant la gravure, on applique avant la gravure une substance de passivation sur le substrat (1) pour également définir ce motif, notamment autour de la partie exposée (3). La substance de passivation permet de former, pendant la gravure, un composé de protection contre la gravure à la périphérie.
PCT/SE2001/002012 2000-09-20 2001-09-20 Procede de gravure par voie humide Ceased WO2002024977A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
JP2002529567A JP4766823B2 (ja) 2000-09-20 2001-09-20 湿式エッチング法
AU2001290424A AU2001290424A1 (en) 2000-09-20 2001-09-20 A method for wet etching

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US23418400P 2000-09-20 2000-09-20
SE0003345-6 2000-09-20
SE0003345A SE517275C2 (sv) 2000-09-20 2000-09-20 Sätt vid våtetsning av ett substrat
US60/234,184 2000-09-20

Publications (1)

Publication Number Publication Date
WO2002024977A1 true WO2002024977A1 (fr) 2002-03-28

Family

ID=26655241

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/SE2001/002012 Ceased WO2002024977A1 (fr) 2000-09-20 2001-09-20 Procede de gravure par voie humide

Country Status (3)

Country Link
CN (1) CN1243849C (fr)
AU (1) AU2001290424A1 (fr)
WO (1) WO2002024977A1 (fr)

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6916584B2 (en) 2002-08-01 2005-07-12 Molecular Imprints, Inc. Alignment methods for imprint lithography
US6921615B2 (en) 2000-07-16 2005-07-26 Board Of Regents, The University Of Texas System High-resolution overlay alignment methods for imprint lithography
US6929762B2 (en) 2002-11-13 2005-08-16 Molecular Imprints, Inc. Method of reducing pattern distortions during imprint lithography processes
US6932934B2 (en) 2002-07-11 2005-08-23 Molecular Imprints, Inc. Formation of discontinuous films during an imprint lithography process
US6990870B2 (en) 2002-12-12 2006-01-31 Molecular Imprints, Inc. System for determining characteristics of substrates employing fluid geometries
US7071088B2 (en) 2002-08-23 2006-07-04 Molecular Imprints, Inc. Method for fabricating bulbous-shaped vias
US7077992B2 (en) 2002-07-11 2006-07-18 Molecular Imprints, Inc. Step and repeat imprint lithography processes
US7122079B2 (en) 2004-02-27 2006-10-17 Molecular Imprints, Inc. Composition for an etching mask comprising a silicon-containing material
US7136150B2 (en) 2003-09-25 2006-11-14 Molecular Imprints, Inc. Imprint lithography template having opaque alignment marks
US7547398B2 (en) 2006-04-18 2009-06-16 Molecular Imprints, Inc. Self-aligned process for fabricating imprint templates containing variously etched features
US8850980B2 (en) 2006-04-03 2014-10-07 Canon Nanotechnologies, Inc. Tessellated patterns in imprint lithography
US9223202B2 (en) 2000-07-17 2015-12-29 Board Of Regents, The University Of Texas System Method of automatic fluid dispensing for imprint lithography processes

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5279702A (en) * 1992-09-30 1994-01-18 Texas Instruments Incorporated Anisotropic liquid phase photochemical copper etch
WO1999045179A1 (fr) * 1998-03-05 1999-09-10 Obducat Ab Procede d'attaque

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5279702A (en) * 1992-09-30 1994-01-18 Texas Instruments Incorporated Anisotropic liquid phase photochemical copper etch
WO1999045179A1 (fr) * 1998-03-05 1999-09-10 Obducat Ab Procede d'attaque

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6921615B2 (en) 2000-07-16 2005-07-26 Board Of Regents, The University Of Texas System High-resolution overlay alignment methods for imprint lithography
US9223202B2 (en) 2000-07-17 2015-12-29 Board Of Regents, The University Of Texas System Method of automatic fluid dispensing for imprint lithography processes
US7077992B2 (en) 2002-07-11 2006-07-18 Molecular Imprints, Inc. Step and repeat imprint lithography processes
US6932934B2 (en) 2002-07-11 2005-08-23 Molecular Imprints, Inc. Formation of discontinuous films during an imprint lithography process
US7338275B2 (en) 2002-07-11 2008-03-04 Molecular Imprints, Inc. Formation of discontinuous films during an imprint lithography process
US6916584B2 (en) 2002-08-01 2005-07-12 Molecular Imprints, Inc. Alignment methods for imprint lithography
US7071088B2 (en) 2002-08-23 2006-07-04 Molecular Imprints, Inc. Method for fabricating bulbous-shaped vias
US6929762B2 (en) 2002-11-13 2005-08-16 Molecular Imprints, Inc. Method of reducing pattern distortions during imprint lithography processes
US6990870B2 (en) 2002-12-12 2006-01-31 Molecular Imprints, Inc. System for determining characteristics of substrates employing fluid geometries
US7136150B2 (en) 2003-09-25 2006-11-14 Molecular Imprints, Inc. Imprint lithography template having opaque alignment marks
US7122079B2 (en) 2004-02-27 2006-10-17 Molecular Imprints, Inc. Composition for an etching mask comprising a silicon-containing material
US8850980B2 (en) 2006-04-03 2014-10-07 Canon Nanotechnologies, Inc. Tessellated patterns in imprint lithography
US7547398B2 (en) 2006-04-18 2009-06-16 Molecular Imprints, Inc. Self-aligned process for fabricating imprint templates containing variously etched features

Also Published As

Publication number Publication date
AU2001290424A1 (en) 2002-04-02
CN1243849C (zh) 2006-03-01
CN1469939A (zh) 2004-01-21

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