EP2232532A2 - Method for local etching of the surface of a substrate - Google Patents

Method for local etching of the surface of a substrate

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Publication number
EP2232532A2
EP2232532A2 EP08872521A EP08872521A EP2232532A2 EP 2232532 A2 EP2232532 A2 EP 2232532A2 EP 08872521 A EP08872521 A EP 08872521A EP 08872521 A EP08872521 A EP 08872521A EP 2232532 A2 EP2232532 A2 EP 2232532A2
Authority
EP
European Patent Office
Prior art keywords
substrate
plasma
polymer
etching
buffer
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.)
Withdrawn
Application number
EP08872521A
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German (de)
French (fr)
Inventor
Laurent Jalabert
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.)
Centre National de la Recherche Scientifique CNRS
Original Assignee
Centre National de la Recherche Scientifique CNRS
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Filing date
Publication date
Application filed by Centre National de la Recherche Scientifique CNRS filed Critical Centre National de la Recherche Scientifique CNRS
Publication of EP2232532A2 publication Critical patent/EP2232532A2/en
Withdrawn legal-status Critical Current

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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 at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
    • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System 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
    • H01L21/3105—After-treatment
    • H01L21/31058—After-treatment of organic layers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
    • B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
    • B81C1/00—Manufacture or treatment of devices or systems in or on a substrate
    • B81C1/00015—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems
    • B81C1/00206—Processes for functionalising a surface, e.g. provide the surface with specific mechanical, chemical or biological properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y10/00—Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00—Manufacture or treatment of nanostructures
    • 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
    • G03F7/0002—Lithographic processes using patterning methods other than those involving the exposure to radiation, e.g. by stamping
    • 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
    • H01L21/027—Making masks on semiconductor bodies for further photolithographic processing not provided for in group H01L21/18 or H01L21/34
    • H01L21/033—Making masks on semiconductor bodies for further photolithographic processing not provided for in group H01L21/18 or H01L21/34 comprising inorganic layers
    • 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 at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
    • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System 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
    • H01L21/302—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to change their surface-physical characteristics or shape, e.g. etching, polishing, cutting
    • H01L21/306—Chemical or electrical treatment, e.g. electrolytic etching
    • H01L21/3065—Plasma etching; Reactive-ion etching
    • 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 at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
    • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System 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
    • H01L21/302—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to change their surface-physical characteristics or shape, e.g. etching, polishing, cutting
    • H01L21/306—Chemical or electrical treatment, e.g. electrolytic etching
    • H01L21/308—Chemical or electrical treatment, e.g. electrolytic etching using masks
    • H01L21/3081—Chemical or electrical treatment, e.g. electrolytic etching using masks characterised by their composition, e.g. multilayer masks, materials
    • 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 at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
    • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System 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
    • H01L21/3105—After-treatment
    • 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 at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
    • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System 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
    • H01L21/3105—After-treatment
    • H01L21/311—Etching the insulating layers by chemical or physical means
    • H01L21/31127—Etching organic layers
    • H01L21/31133—Etching organic layers by chemical means
    • H01L21/31138—Etching organic layers by chemical means by dry-etching
    • 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 at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
    • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System 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
    • H01L21/3105—After-treatment
    • H01L21/311—Etching the insulating layers by chemical or physical means
    • H01L21/31144—Etching the insulating layers by chemical or physical means using masks

Definitions

  • the present invention relates to a method of localized etching of a surface, in particular to create micrometric and nanometric patterns directly in a substrate.
  • US Patent Application 2007/0269 883 (ULRICH) relates to a method of localized modification of the surface energy of a substrate in which a buffer having through channels is brought into contact with a substrate, giving rise to a spot treatment of the surface because the radicals from the plasma can penetrate through the ends of the channels and locally treat the surface.
  • the basic idea of the invention is to put a substrate locally in contact with species (radicals, ions, atoms) derived from a plasma by using as a selective interface a structured polymer buffer through which the species can diffuse up to in contact with the substrate to locally modify the surface energy and / or to etch the substrate or a thin film deposited on a substrate, or to etch a hydrophobic monolayer deposited by plasma on a substrate or on a thin film.
  • species radicals, ions, atoms
  • the invention thus relates to a method of etching a substrate characterized in that it implements: a) producing a gas permeable polymer pad which comprises patterns in relief; b) contacting the raised patterns with the substrate; c) subjecting the buffer and substrate assembly to a plasma such that species present in the plasma are accelerated and diffuse through the polymer from a surface of the buffer to the substrate through the raised patterns in contact with the substrate.
  • the polymer may be an organic polymer, in particular comprising polycarbonate chains.
  • This may include polydimethylsiloxane PDMS or any other polymer having the property of being permeable in a plasma, for example PPMS, PTFPMS, PPhMS, polychloroprene, PTEMA, polybutadiene (cis), polyisoprene, or else a polyacetylene film, or phosphazene polymer in PTFEP.
  • the device having a surface topography is called a buffer.
  • the buffer may have a thickness of between a few microns and several millimeters, in particular between 40 and 3 mm, and more particularly between 100 and 1 mm.
  • its thickness is chosen so that it can be handled in step b by a user or a machine.
  • the substrate solid or in the form of a thin film deposited on a solid substrate by conventional techniques of microelectronics, can be in particular a metallic material, insulator, semiconductor and / or polymer.
  • the substrate may be, for example, silicon-based or silicon-based, such as SiO 2 , nitride, oxynitrides, glass ("pyrex", fused silica, quartz), or metal, especially Cu, Au, Al, ITO. , Ni, Ti, Pt.
  • silicon-based or silicon-based such as SiO 2 , nitride, oxynitrides, glass ("pyrex", fused silica, quartz), or metal, especially Cu, Au, Al, ITO. , Ni, Ti, Pt.
  • the gas (s) used to generate the plasma may be: C 4 F 8 , CF 4 , SF 6 , CHF 31 N 2 , O 2 , HMDS (hexamethyldisilazane) and / or HMDSO (hexamethyldisiloxane).
  • a carbofluorinated gas can be used to create a plasma that allows the deposition of a hydrophobic PTFE layer.
  • An oxygen-based gas (O 2 , O 3 for example) can be used to create a hydrophilic surface or to engrave a polymer-based material (resins ...) or to etch a layer of PTFE.
  • the method can be characterized in that the plasma contains reactive species capable of etching the surface of the substrate and in that step c) is continued until an etching of said surface is obtained.
  • the surface of the plasma comprises a deposited layer and in that said etching consists in etching said deposited layer until reaching an underlying layer or the substrate itself.
  • FIGS. 1a to 1f illustrate an example of implementation of the invention. method of the invention for locally producing hydrophilic and hydrophobic zones.
  • An application of the present invention relates to the possibility of locally modifying the surface energy of a material by localized etching of a hydrophobic monolayer previously deposited by a plasma method.
  • An application example is described below by relying on the localized etching of said hydrophobic monolayer previously deposited by plasma on a substrate coated with a copper deposit, to allow the localized growth of nanometric gold patterns by deposition. electrochemical.
  • Such localized etching has a significant interest in the development of alternative techniques for deposition or selective growth of metals on a substrate, or on localized etching of nanometric patterns in a substrate.
  • the invention makes it possible to dispense with the known and time-consuming methods that combine electron beam writing on an electron-sensitive resin, developing the resin in a chemical developer to create openings on the substrate. , the deposition of metal on the surface composed of resin patterns and openings on the substrate, then the chemical etching of the resin to reveal only the metal in contact with the substrate (lift-off process).
  • the adhesion of biological products depend on the surface energy of a substrate.
  • the adhesion of biological molecules and the electrochemical growth take place preferentially on hydrophilic surfaces. It is therefore advantageous to have a simple, fast and reliable technique for locally etching a substrate or a thin film, in particular for locally etching a hydrophobic thin film deposited on an initially hydrophilic substrate, so as to create a localized modification of the surface energy of this substrate, particularly at the nanoscale.
  • the invention is based on the combination of the plasma assisted etching and deposition technique and the contact printing technique on a substrate of a polymer pad having a surface topography (called micro-contact printing). ).
  • radicals derived from a plasma diffuse through a polymer buffer having a surface topography and contacted with a substrate, for etching the substrate locally or a thin film deposited on this substrate.
  • the microcontact printing technique on a substrate, a polymer pad having patterns on its surface is well known, in particular for locally depositing molecules initially fixed on the pad by soaking in a chemical solution. Soaking the buffer in a chemical solution makes it possible to cover the entire polymer buffer with monolayers of chemical solution. Due to the surface topography present on the polymer pad, upon contact with a substrate, the chemical solution monolayers are transferred to the substrate from the patterns contacted with the substrate.
  • the monolayer of chemical solution is hydrophobic, which is the case of monolayers based on OTS (orthotrimethylsiloxane) and its derivatives, it is then possible to create hydrophobic units locally on a substrate when a buffer in polymer having a surface topography and pre-soaked with OTS by soaking in a chemical solution, is brought into contact with said substrate.
  • OTS orthotrimethylsiloxane
  • the invention is based on an original combination of the contact printing technique (known as "micro-contact printing") and cold plasma surface etching.
  • a thin polymer film having three-dimensional patterns on one of the faces (called a polymer pad) is contacted with a substrate such that the patterns on the pad are in contact with the substrate.
  • the whole is placed in a cold plasma.
  • the species (radicals, ions, atoms, etc.) produced by the plasma diffuse through the buffer to the substrate via the contact zones defined by the patterns of the polymer buffer.
  • a hydrophobic thin film is deposited by plasma over the entire surface of an initially hydrophilic substrate, for example a substrate based on SiO 2 or any other material whose surface is hydrophilic.
  • the plasma deposition of a hydrophobic thin film uniformly over the entire surface of the hydrophilic substrate can easily be obtained from carbofluorocarbon gas of the C4F8 or CHF3 type (without however being limited to these types of carbofluorinated gas only).
  • the polymer pad is contacted with the hydrophobic thin film substrate such that the patterns on the pad are contacted with the hydrophobic thin film on the surface of the substrate.
  • the patterns of the pad are not open, and the entire surface of the substrate can be covered by the polymer pad.
  • An oxygen based plasma is used to etch a plasma deposited hydrophobic thin film onto a substrate from carbofluorinated gases.
  • the assembly is subjected to an oxygen-based plasma for example, so that the radicals from the plasma diffuse through the buffer until the hydrophobic thin film previously deposited on the substrate. It becomes possible to locally create on a substrate hydrophobic and hydrophilic zones defined by the patterns of the polymer buffer placed in contact with the substrate and subjected to a cold plasma.
  • the polymer pad is obtained by molding a polymer on a rigid mold.
  • the rigid mold comprises three-dimensional patterns on one of the faces.
  • the three-dimensional patterns of the mold can be realized in two main technological steps including a lithography technique and an engraving technique without being limited to the combination of these two only techniques.
  • Electronic lithography, photolithography or nanoimpression are the most commonly used techniques for generating patterns in a resin deposited on a substrate (the resin is called masking resin).
  • This resin serves as a mask for the etching of the substrate.
  • the etching of the substrate can be carried out wet, by dipping in liquid chemical solutions, or by dry process such as cold plasma etching.
  • the masking resin can be removed by surface cleaning techniques, either liquid or dry.
  • the polymer buffer may be obtained for example from PDMS (polydimethylsiloxane) type polymers deposited on the surface of the mold having the 3-dimensional topography.
  • the PDMS type polymer may be in liquid form (low viscosity) to match the shape of the patterns present on the mold. To obtain patterns on the pad, it is necessary to increase the viscosity of the polymer in contact with the mold, to make it manipulable and transferable to the substrate. To do this, it is possible to add a chemical agent promoting crosslinking. Crosslinking occurs especially during thermal annealing.
  • the method of crosslinking the polymer buffer then depends on the properties of the chemical agent used and the annealing conditions.
  • a liquid polymer based on polydimethylsiloxane or PDMS can be crosslinked by adding a chemical agent based on tetramethyltetravinylcyclotetrasiloxane (Dow Corning Company 'Sylgard 184 curing agent'), which by heat treatment, significantly increases the viscosity of the mixture to obtain a thin and flexible at least partially crosslinked film allowing the patterns of the buffer retain their dimension when they are brought into contact with the substrate.
  • the polymer pad is then deposited on a substrate so that the relief patterns present on the structured face are in contact with the substrate. This operation is similar to the micro contact printing technique (micro contact printing) without using a molecular "ink”.
  • the soft buffer / substrate assembly is introduced into a plasma treatment frame.
  • Plasma is generated from ionized gas molecules from capacitive sources (of the RIE type for example) or from high density sources (of the ECR, helicon or ICP-RIE type, for example).
  • the radicals present in the plasma may be in the form of ions, neutral species, atoms or molecules excited and / or partially ionized.
  • the self-biasing voltage allows the diffusion of the radicals towards the substrate, the energy and the density of the radicals depend essentially on the pressure and power of the only generator used to generate the plasma.
  • the energy of the radicals and the density of the plasma can be adjusted separately via two power generators.
  • Region B the region where the patterns are in contact with the substrate.
  • the patterns present in the PDMS buffer are, for example, not open at the ends of the buffer.
  • the periphery of the PDMS buffer is then in contact with the substrate.
  • the buffer is manually removed from the substrate.
  • the patterns present on the polymer buffer (buffer placed in contact with the substrate and subjected to plasma treatment) are then transferred to the substrate.
  • PDMS is a material particularly suitable for producing the flexible pad because of its ease of implementation and its low cost.
  • the radicals created by cold plasma can be obtained in particular from the following gases: C 4 F 8 , CF 4 , CHF 3 , C 2 F 6 , SF 611 N 2 , O 2 , Cl 2 , SiCl 4 , HDMS and / or HDMSO.
  • the substrate may have an initial surface energy (intrinsic depending on the nature of the material) and / or be pretreated to uniformly modify the surface energy over the entire surface.
  • the surface energy of a substrate can initially be modified by a global treatment of the surface of a substrate, for example by soaking the substrate in a chemical solution, or by vapor phase treatment, or by assisted deposition by cold plasma, so that a thin film covers the entire surface of the substrate.
  • the substrate may advantageously have an intrinsic surface energy of hydrophilic type (low contact angle, typically less than 10 ° for a drop of water D1 at 20 ° C.), hydrophobic (high contact angle, typically greater than 90 ° for a drop of water DI at 20 0 C).
  • Substrates having an intermediate surface energy can be used in the context of the present invention.
  • the substrates may be, for example, silicon, glass, plastic, metal, or any type of thin film deposited on a substrate by evaporation, sputtering, plasma assisted deposition, spray deposition techniques, deposition by centrifugation ("spin coating") or deposition by ink jet, ...
  • a hydrophilic treatment may be obtained for example from an oxygen-based plasma, HMDSO or HMDS, or else by vapor phase treatment of HMDS in an enclosure, for example of the YES-3TA type or YES-5TA from Yield Engineering Inc.
  • An oxygen plasma is commonly used to remove polymer-type organic residues, particularly in the case of polymers used in a surface patterning process such as photolithography, electron beam writing, or nanoimprinting.
  • the oxygen plasma is also used to promote the adhesion of PDMS-type polymers to a substrate, in particular to modify the surface energy of the PDMS by oxidation of its surface induced by the oxygen plasma treatment.
  • the PDMS thus treated has a hydrophilic surface which improves its adhesion with another polymer (which may also be PDMS) or a substrate, when the PDMS polymer is brought into contact with the substrate.
  • Another technique for improving the adhesion of two PDMS films (in the English bonding terminology) consists in bringing the two PDMS films into contact, then submitting the assembly to an oxygen plasma: in the latter case, the adhesion Both films are firmly established so that the two films can not be separated.
  • Hydrophobic treatment over the entire surface of the substrate can be obtained by deposition of polymers (especially PTFE) by plasma for example from carbofluorinated gas type C 4 F 8 or CHF 3 commonly used in cold plasma processes.
  • polymers especially PTFE
  • C 4 F 8 or CHF 3 carbofluorinated gas type C 4 F 8 or CHF 3 commonly used in cold plasma processes.
  • As a function of the residence time of radicals originating from the plasma which depends mainly on the pressure and / or the gas flow rates introduced into the chamber of a machine adapted to the cold plasma generation, it is possible to etch a substrate or it is well to deposit some monolayers of polymers, in particular layers based on C x F y (in particular C 2 F 2 ) which have the property of rendering the surface of a substrate hydrophobic.
  • the radicals based on C x F y are generated in a plasma using, for example, carbofluorinated gases of the CHF 3 or C 4 F 8 type .
  • the residence time can be calculated with the formula given in US6749763 (IMAI). It is for example between 1 millisecond and a few seconds, for example 5 seconds.
  • silicone polymers as mentioned in the article by S. G. CHARATI and S. A. STERN "Diffusion of Gases in Silicone Polymers: Molecular Dynamics Simulations" published in Macromolecules, 1998, 31, p. 5529 to 5535, namely poly-propylmethylsiloxane (PPMS), poly-trifluoropropyl-methylsiloxane (PTFPMS) and polyphenylmethylsiloxane (PPhMS), may also be suitable for the practice of the invention.
  • PPMS poly-propylmethylsiloxane
  • PTFPMS poly-trifluoropropyl-methylsiloxane
  • PPhMS polyphenylmethylsiloxane
  • a "master" silicon wafer 1 is manufactured by lithography (by electron beam or photolithography) followed by dry or wet phase etching to obtain the desired hollow and relief patterns on a depth which is for example about 100 nm.
  • the photoresist is then removed by a dry or wet phase attack.
  • a polymer layer 2 for example PDMS, is deposited on the silicon wafer 1.
  • the assembly is heated in an oven to obtain at least partial crosslinking of the polymer.
  • the buffer 2 'of at least partially crosslinked polymer is demolded and the raised patterns 3 of the face 4 of the "master" wafer 1 are reproduced in negative 5 in the face 6 of the buffer 2'.
  • the face 7 of the pad 2 'not in contact with the wafer 1 is flat and the face 6 of the pad 2' has a topography 5 comprising positive nanometric patterns (pads, lines) which is the reverse of the patterns 3 of the face 4 of the plate 1.
  • the face 6 of the buffer 2 ' is applied to the face 11 of a substrate 10 which has been previously treated to be hydrophilic or hydrophobic or which is hydrophilic or hydrophobic in nature.
  • the assembly consisting of the buffer 2 'and the substrate 10 applied against each other is introduced into an ICP-RIE ion-coupling type reactive ion plasma machine ("Inductively Coupled Plasma - Reactive Ion Etching "), for example an Omega 201 Omega machine equipped with two 13.56 MHz radiofrequency sources to control separately the plasma density and the energy of the radicals. It undergoes a treatment in a high density plasma containing carbofluorinated molecules to achieve hydrophobic patterns (on a hydrophilic face 11) or oxygen molecules to achieve hydrophilic patterns (on a hydrophobic face 11).
  • ICP-RIE ion-coupling type reactive ion plasma machine for example an Omega 201 Omega machine equipped with two 13.56 MHz radiofrequency sources to control separately the plasma density and the energy of the radicals. It undergoes a treatment in a high density plasma containing carbofluorinated molecules to achieve hydrophobic patterns (on a hydrophilic face 11) or oxygen molecules to achieve hydrophilic patterns (on a hydrophobic face 11).
  • the species generated by this plasma are not in direct contact with the substrate, but diffuse through the polymer to the interface with the substrate 10 to produce localized treatment at the contact zones between the patterns and the face 11.
  • hydrophobic or hydrophilic zones 12 are present on the face 11, which outside of these zones is respectively hydrophilic or hydrophobic.
  • Step 1 Examples of Pretreatment of a Substrate by Plasma Hydrophobic Thin Film Deposition:
  • the hydrophobic layer deposition on the entire surface of a substrate can be obtained by using an inductively coupled ionic reactive ion etching (ICP-RIE) type cold plasma etching machine such as the Omega machine. 201 from AVIZA-Technology.
  • ICP-RIE inductively coupled ionic reactive ion etching
  • the CHF 3 gas with a flow rate of 50 cm 3 / min, at a pressure of between 30mTorr and 50 mTorr and a source power torque / sample support 500 W / 20 W the residence time of the radicals thus generated is favorable to the deposition of hydrophobic polymer based on C x F y .
  • composition of the hydrophobic polymer based on C x F y namely the x and y values, is poorly identified in the literature. It is sometimes stated that this composition would be C2F2.
  • this type of hydrophobic monolayer deposition is very widely used especially in deep silicon etching (Deep Reactive Ion Etching) processes.
  • hydrophobic layer deposition is commonly used in deep silicon etching (Deep Reactive Ion Etching) processes, which successively involve a C x F x polymer deposition cycle from the C 4 F 8 gas followed by a silicon etching cycle from SF6 / O2 gas.
  • the polymer deposit C x F y is obtained with a flow rate of C 4 F 8 for example between 80 and 110 cm 3 / min, a pressure of between 10 and 20 mTorr, and a source / power torque. 600W / OW sample holder.
  • the hydrophobic polymer deposit C x F y obtained in the case of a plasma generates from the dissociation of the C 4 F 8 gas in the electromagnetic field induced by the application of a radio frequency power. frequency on the source (coil), operates effectively when the power applied on the substrate support (bias) is zero, or OW. In other words, under these conditions, there is no directional bombardment of the radicals towards the substrate since the power applied to the support of the substrate is zero. If the power applied on the support of the substrate is ideally greater than 10W, typically 5OW, the bombardment of the substrate by the radicals of type C x F y becomes effective, leading to a phenomenon no longer deposition of hydrophobic layer, but etching of the substrate.
  • Step 2 Example of preparation of the polymer buffer.
  • the PDMS (Sylgard 184) is introduced into a beaker, then the hardener (for example Sylgard Curing Agent) at a mass proportion of about 10%.
  • the mixture is mixed and then placed under a vacuum bell for, for example, 5 minutes in order to cause the degassing of air bubbles formed in the mixture during homogenization of the PDMS and its curing agent.
  • This degassed and homogenous mixture should be used within a few hours (and at the latest one day) depending on the preparation.
  • the PDMS and its hardener are mixed under vacuum and the mixture is stored under vacuum.
  • DOPAG MICROMIX Cham - Switzerland. This type of equipment makes it possible to reduce the preparation time of the PDMS by avoiding mixing and degassing steps.
  • Step 3 Example of filling a mold with the PDMS / hardener mixture
  • the rigid mold having three-dimensional patterns on one of these faces can be made from a silicon substrate on which patterns have been reported by the combination of standard lithography and etching techniques.
  • the rigid mold is defined as a "master" wafer.
  • the method using the "spinette” implements a machine having a flat disk on which is placed a substrate held by suction in its center. A liquid is deposited on the substrate manually, or using a pipette or an automated system. The disc is rotated. Depending on the speed of rotation of the disc, it is possible to obtain different thicknesses of the polymer). Depending on the rotational speed, typically between 500 rpm and 10000 rpm, the "spin", and the viscosity of the polymer, it is possible to obtain very thin films of PDMS up to 40 ⁇ m thick, but which then require precautions for their handling. This is why a thickness of about one millimeter seems the most advantageous compromise.
  • the assembly is placed in an oven or on a hot plate so that the temperature rise induces the crosslinking of the monomers present in the PDMS via the curing agent.
  • the cooking of the poured or spread PDMS polymer is continued for a few hours (approximately 3 to 4 hours) between 50 ° C. and 80 ° C., or more rapidly at higher temperatures, for example about 10 minutes to 15 minutes at 110 ° C. vs.
  • Step 4 - Example of bringing the PDMS buffer into contact with the substrate:
  • a manual demolding is carried out to remove the PDMS from the "master” wafer.
  • the pads and cavities initially present on the "master” plate are transferred into the PDMS in cavities and pads respectively.
  • the PDMS comprising the patterns after demolding is called a PDMS buffer and is in the form of a transparent thick film.
  • the face of the PDMS buffer comprising the patterns is placed manually in contact with the surface of the substrate to be treated, without introducing bubbles between the buffer and the substrate.
  • Step 5 Demonstration of the effect obtained during the plasma treatment of the assembly defined by the buffer placed in contact with the substrate:
  • the first example relates to the localized modification of the surface energy of a substrate from a PDMS buffer comprising micrometric units: in this case, the observation of the effect produced is easily and rapidly demonstrated by optical microscopy.
  • the second example aims to demonstrate that the effect described by the invention applies to the nanoscale. In this case, the observation by optical microscopy can not be conclusive considering the fact that the localized modification of the surface of the substrate takes place on areas of nanometric dimensions.
  • a Electrochemical metal growth technique is used. This type of growth works favorably on a hydrophilic and conductive substrate. On the other hand, the growth takes place more difficultly with a surface that is not very conductive and hydrophobic.
  • the substrate which in this example is a silicon wafer, is covered with a layer of SiO 2 of 200 nm.
  • the initial contact angle measurement on the substrate is 9 °, reflecting the usual hydrophilic character intrinsic to the SiO 2 layer covering the surface of the substrate.
  • Steps 2, 3 and 4 are identical.
  • the substrate therefore comprises a silicon wafer covered with SiO 2 and a hydrophobic thin film of a few nanometers in thickness.
  • the PDMS buffer covers the entire wafer. The assembly is introduced into the Omega201 plasma ICP-RIE etching machine, to subject the surface of the plasma buffer.
  • Oxygen O 2 is introduced into the chamber with a flow rate of 40 cm 3 / min.
  • the pressure is 25mTorr.
  • a radiofrequency power of 500W to the source (that is to say on the coil surrounding the enclosure of the ICP-RIE machine)
  • the O 2 molecules are dissociated into atom-based radicals. of ionized oxygen.
  • a radio frequency power of 1OW for 3 minutes on the support of the substrate the radicals are attracted to the substrate.
  • region A non-contact
  • the radicals diffused through the PDMS until reaching the hydrophobic layer covering the substrate, and then etching of the hydrophobic layer covering the substrate. Therefore in region A (non-contact), the layer of C x F y is hydrophobic engraved merit' concern the SiO 2 layer hydrophilic.
  • region B contact
  • the radicals diffused through the PDMS until reaching the hydrophobic layer covering the substrate.
  • no change in the contact angle is observed in this region.
  • the substrate Upon removal of the PDMS buffer, the substrate is optically characterized.
  • the treated substrate is positioned on a cell Peltier connected to a temperature controller in the range 5 0 C - 100 0 C. Cooling the substrate, condensation of water droplets present in the atmosphere.
  • micrometric water drops accumulate to form patterns identical to those present on the PDMS buffer.
  • the substrate which is in this example a silicon wafer, is covered with a Si ⁇ 2 layer of 200 nm thick.
  • the initial contact angle measurement on the substrate is 9.6 °, reflecting the usual and intrinsic hydrophilicity to the SiO 2 layer covering the surface of the substrate.
  • the substrate therefore comprises a silicon wafer coated only with hydrophilic SiO 2 .
  • Steps 2, 3 and 4 are identical. Step 1 is not used for this example.
  • the PDMS buffer covers the entire wafer.
  • the assembly is introduced into an Omega201 plasma ICP-RIE etching machine, to subject the surface of the plasma buffer.
  • a mixture based on C 4 F 8 / CHF 3 is introduced into the chamber with flow rates of 80 and 50 cm 3 / min respectively.
  • the pressure is 45mTorr.
  • a radio-frequency power of 500W on the source ie on the coil surrounding the enclosure of the ICP-RIE machine
  • the molecules of CHF 3 are dissociated into C x F y ionized radicals.
  • a radio frequency power of 10W for 3 minutes on the support of the substrate the radicals C x F x are attracted to the substrate.
  • region A non-contact
  • region B contact
  • the radicals diffused through the PDMS buffer until reaching the hydrophilic layer of SiO 2 covering the substrate.
  • the substrate Upon removal of the PDMS buffer, the substrate is optically characterized.
  • the treated substrate is positioned on a Peltier cell connected to a temperature controller in the range 5 0 C - 100 0 C. Cooling the substrate, condensation of water droplets in the atmosphere occurs: micrometric droplets are form in region A (non contact). Therefore this region is hydrophilic despite the plasma treatment. In region B, no formation of drops of water is observed. After plasma treatment, the B region (contact) became locally hydrophobic.
  • This example demonstrates the possibility offered by the invention of locally creating hydrophobic regions on the surface of an initially hydrophilic substrate, in region (B) where the PDMS buffer motifs were in contact with the substrate during plasma treatment. .
  • the modification of the surface energy in the region A could be due to the etching of the hydrophobic monolayer of a few nanometers in thickness (deposited on the surface of the substrate during the pretreatment of the substrate) during the treatment by O 2 plasma of the substrate / PDMS buffer assembly.
  • Region B apparently unchanged, could have undergone surface modification by migration of monomers from PDMS.
  • the origin of the modification of the surface energy in the B region could also be the migration of monomers resulting from the PDMS during the plasma treatment caused by the diffusion of the CxFy radicals during the C plasma treatment. 4 F 8 / CHF 3 of the PDMS buffer / substrate assembly.
  • region A it is possible that an etching of a few nanometers in depth occurred in the SiO 2 layer, and not over the entire initial thickness of SiO 2 . This is why region A retains a hydrophilic character in this case.
  • Example 3 Localized metal growth at the nanoscale.
  • Metal growth by electrochemistry process as follows. A metal substrate or coated with a metal thin film serving as an electrode is immersed in a bath containing metal ions of the metal that it is desired to deposit on the substrate by the electrochemical process. In the electrochemical bath, by applying a current to the substrate, the metal ions contained in the solution exchange electrons with the conductive surface of the substrate. During this exchange of charges, the metal ions of the metal that it is desired to deposit then turn into a metal atom and deposit on the surface of the substrate.
  • Photosensitive resin patterns may be provided on the conductive substrate to mask areas on the surface and thereby limit charge exchange during the electrochemical deposition process.
  • the invention demonstrates the possibility of locally modifying the surface energy of a conductive substrate to limit the exchange of charges between the conductive substrate and metal ions in an electrochemically deposition process.
  • a gold deposit is made on a 4 inch (10.2 cm) silicon wafer over the entire surface (full plate). The thickness of the deposit is not important for the demonstration.
  • the wafer coated with the gold film is introduced into a plasma etching machine, and a deposit described by Example 1 is carried out on the entire surface (full plate).
  • the contact angle is 101 ° (against 86 ° initially: without treatment).
  • the wafer is removed from the machine.
  • PDMS (10% curing agent - annealing 100 ° C - 15 min) is deposited on another silicon wafer comprising nanometric patterns made by electron beam and direct etching in silicon to a depth of about 100 nm. During the deposition, the liquid PDMS conforms to the shape of the patterns etched in the silicon, and hardens during annealing. The PDMS with a thickness close to several millimeters is removed from the mold. The said PDMS is then called “flexible mold” and has positive nanometric patterns (pads, lines) on one of the faces.
  • the flexible mold of about 3 cm side is deposited on the gold covered wafer and on which was deposited some hydrophobic monolayers based on full plate CxFy (Example 1 described above).
  • the pads and lines forming the patterns of the buffer are not in contact with the gold surface covered with hydrophobic monolayers.
  • the borders of the flexible mold are in contact with the substrate so that the patterns present in the flexible mold are not in contact with the external environment (air).
  • the assembly is reintroduced into the etching machine and an oxygen plasma is applied for 3 minutes in order to render hydrophilic the areas that are not in contact. Therefore, in the zone which is not covered by the PDMS, the surface has become very hydrophilic again because the oxygen plasma etches the initially plasma-deposited CxFy layer (described in Example 1) to re-assemble the 'bare gold (contact angle impossible to measure, the drop is perfectly spread).
  • the hydrophobic zones of the substrate in contact with the flexible mold patterns remain hydrophobic under the action of the plasma which diffuses through the flexible mold material.
  • the surface energy is modified.
  • the wafer After removal of the mold flexible, is placed in an electrochemical bath containing copper ions. Under the action of an electric current, the Cu is preferentially deposited on the exposed hydrophilic gold layer, but the gold coated with a hydrophobic residual layer is also covered with a deposit of smaller thickness (because the presence of hydrophobic zones created by the invention inhibits or limits the exchange of electrons between the copper ions and the gold film covering the substrate).
  • Total or partial electron exchange inhibition between the substrate and the metal ions results in the selective deposition of metal on the substrate, or at least a difference in metal thickness between the initially hydrophilic and hydrophobic areas of the substrate. In all cases, the method leads to an observable image contraction by scanning electron microscopy because of the difference in topography between these different areas treated locally by the invention.
  • a layer of PTFE is deposited by plasma on a substrate, then if this layer is put in contact with the polymer buffer comprising the patterns, then by applying an oxygen plasma, it is possible to locally etch the fine PTFE layer in the region where the patterns are not in contact with the surface of the substrate and reach the substrate or the layer deposited thereon.
  • Example 4 Localized etching of a substrate.
  • etching of a substrate at shallow depths is generally very difficult to control by ICP-RIE or RIE plasma etching techniques.
  • plasma etching is known to generate defects in the substrates due to the direct bombardment of the surface by the radicals from the plasma. The defects induced by the dry etching are unacceptable to the good functioning of the advanced electronic components.
  • the invention makes it possible, thanks to the diffusion through the substrate, to perform the localized etching of a substrate at depths between a few nanometers and several tens of nanometers while avoiding the direct bombardment of the substrate by the radicals originating from the plasma. Localized etching of a substrate does not require lithography techniques and wet or dry etching on said substrate.
  • the PDMS buffer comprising patterns defined on one of these faces, is brought into contact with a substrate, for example silicon.
  • the set is placed in an engraving machine by plasma.
  • the reactive gases are chosen so that a chemical reaction between the substrate and the radicals originating from the plasma is possible so that the etching phenomenon is effective.
  • SF6 gas is particularly suitable for engraving a silicon substrate.
  • the appearance of patterns etched in the silicon is optically observed.
  • the plasma or reactive species of the plasma have passed through the buffer to locally reach the substrate where the patterns are not in contact with it and etched the substrate locally. In the areas of contact between the buffer and the substrate, the etching is not observed.
  • the height of the patterns of the stamp is greater (or possibly equal) to the minimum width of the patterns, or in other words that the aspect ratio of the height / width of the patterns of the stamp is greater (or possibly equal) to 1.

Abstract

The invention relates to a method for the local etching of the surface of a substrate, characterised in that it comprises: a) making a gas-pervious polymer pad that comprises three-dimensional patterns on one surface thereof; b) contacting the surface including the pad patterns with the substrate; c) submitting the pad/substrate assembly to a plasma so that the species present in the plasma are accelerated and diffused through the pad until they reach the substrate.

Description

PROCEDE DE GRAVURE LOCALISEE DE LA SURFACE D'UN SUBSTRAT. METHOD OF LOCALLY ENGRAVING THE SURFACE OF A SUBSTRATE
La présente invention a pour objet un procédé de gravure localisée d'une surface, en particulier pour créer des motifs micrométriques et nanométriques directement dans un substrat.The present invention relates to a method of localized etching of a surface, in particular to create micrometric and nanometric patterns directly in a substrate.
On connaît déjà des procédés de modification de l'énergie d'un substrat à l'aide d'un plasma.Methods for modifying the energy of a substrate using a plasma are already known.
La Demande de Brevet US 2007/0269 883 (ULRICH) concerne un procédé de modification localisée de l'énergie de surface d'un substrat dans lequel un tampon présentant des canaux débouchants est mis en contact avec un substrat, donnant lieu a un traitement localisé de la surface du fait que les radicaux issus du plasma puissent pénétrer par les extrémités des canaux et traiter localement la surface.US Patent Application 2007/0269 883 (ULRICH) relates to a method of localized modification of the surface energy of a substrate in which a buffer having through channels is brought into contact with a substrate, giving rise to a spot treatment of the surface because the radicals from the plasma can penetrate through the ends of the channels and locally treat the surface.
Il en va de même de la demande de Brevet US 2006/116001 (WANG) dans laquelle les motifs en relief d'un tampon servent de masque pour soumettre les portions du substrat laissées à découvert à un traitement de modification d'énergie tel que l'exposition à un plasma.The same is true of US Patent Application 2006/116001 (WANG) in which the relief patterns of a stamp serve as a mask for subjecting the portions of the substrate left exposed to an energy modification treatment such that the exposure to a plasma.
L'idée de base de l'invention est de mettre un substrat localement en contact avec des espèces (radicaux, ions, atomes) issues d'un plasma en utilisant comme interface sélective un tampon structuré en polymère à travers lequel les espèces peuvent diffuser jusqu'au contact avec le substrat pour en modifier localement l'énergie de surface et/ou pour graver le substrat ou un film mince déposé sur un substrat, ou encore pour graver une monocouche hydrophobe déposée par plasma sur un substrat ou sur un film mince.The basic idea of the invention is to put a substrate locally in contact with species (radicals, ions, atoms) derived from a plasma by using as a selective interface a structured polymer buffer through which the species can diffuse up to in contact with the substrate to locally modify the surface energy and / or to etch the substrate or a thin film deposited on a substrate, or to etch a hydrophobic monolayer deposited by plasma on a substrate or on a thin film.
L'invention concerne ainsi un procédé de gravure d'un substrat caractérisé en ce qu'il met en œuvre : a) réaliser un tampon en polymère perméable aux gaz qui comporte des motifs en relief ; b) mettre en contact les motifs en relief avec le substrat ; c) soumettre l'ensemble constitué par le tampon et le substrat à un plasma de sorte que des espèces présentes dans le plasma sont accélérées et diffusent à travers le polymère depuis une surface du tampon jusqu'au substrat à travers les motifs en relief en contact avec le substrat.The invention thus relates to a method of etching a substrate characterized in that it implements: a) producing a gas permeable polymer pad which comprises patterns in relief; b) contacting the raised patterns with the substrate; c) subjecting the buffer and substrate assembly to a plasma such that species present in the plasma are accelerated and diffuse through the polymer from a surface of the buffer to the substrate through the raised patterns in contact with the substrate.
Le polymère peut être un polymère organique, comportant notamment des chaînes polycarbonées. Il peut s'agir notamment de polydiméthylsiloxane PDMS ou de tout autre polymère ayant la propriété d'être perméable dans un plasma, par exemple PPMS, PTFPMS, PPhMS, polychloroprène, PTEMA, polybutadiène(cis), polyisoprène, ou bien encore un film de polyacétylène, ou de polymère phosphazène en particulier PTFEP. Le dispositif présentant une topographie de surface est appelé tampon.The polymer may be an organic polymer, in particular comprising polycarbonate chains. This may include polydimethylsiloxane PDMS or any other polymer having the property of being permeable in a plasma, for example PPMS, PTFPMS, PPhMS, polychloroprene, PTEMA, polybutadiene (cis), polyisoprene, or else a polyacetylene film, or phosphazene polymer in PTFEP. The device having a surface topography is called a buffer.
Le tampon peut avoir une épaisseur comprise entre quelques microns et plusieurs millimètres, notamment entre 40μ et 3 mm, et plus particulièrement entre 100μ et 1 mm. Avantageusement son épaisseur est choisie pour qu'il soit manipulable à l'étape b par un utilisateur ou une machine.The buffer may have a thickness of between a few microns and several millimeters, in particular between 40 and 3 mm, and more particularly between 100 and 1 mm. Advantageously, its thickness is chosen so that it can be handled in step b by a user or a machine.
Le substrat, massif ou sous forme de film mince déposé sur un substrat massif par les techniques conventionnelles de la microélectronique, peut être en particulier un matériau métallique, isolant, semiconducteur et /ou polymère.The substrate, solid or in the form of a thin film deposited on a solid substrate by conventional techniques of microelectronics, can be in particular a metallic material, insulator, semiconductor and / or polymer.
Le substrat peut être par exemple en silicium ou à base de silicium comme le Siθ2 , du nitrure, des oxynitrures, du verre ("pyrex", silice fondue, quartz), ou en métal, notamment en Cu, Au, Al, ITO, Ni, Ti, Pt.The substrate may be, for example, silicon-based or silicon-based, such as SiO 2 , nitride, oxynitrides, glass ("pyrex", fused silica, quartz), or metal, especially Cu, Au, Al, ITO. , Ni, Ti, Pt.
Le ou les gaz utilisés pour générer le plasma peut être : C4F8, CF4, SF6, CHF31N2, O2, HMDS (hexaméthyldisilazane) et/ou HMDSO (hexaméthyldisiloxane).The gas (s) used to generate the plasma may be: C 4 F 8 , CF 4 , SF 6 , CHF 31 N 2 , O 2 , HMDS (hexamethyldisilazane) and / or HMDSO (hexamethyldisiloxane).
Un gaz carbofluoré peut être utilisé pour créer un plasma qui permet le dépôt d'une couche de PTFE hydrophobe.A carbofluorinated gas can be used to create a plasma that allows the deposition of a hydrophobic PTFE layer.
Un gaz à base d'oxygène (O2, O3 par exemple) peut être utilisés pour créer une surface hydrophile ou graver un matériau à base de polymère (résines ...) ou encore graver une couche de PTFE.An oxygen-based gas (O 2 , O 3 for example) can be used to create a hydrophilic surface or to engrave a polymer-based material (resins ...) or to etch a layer of PTFE.
Le procédé peut être caractérisé en ce que le plasma contient des espèces réactives aptes à graver la surface du substrat et en ce que l'étape c) est poursuivie jusqu'à l'obtention d'une gravure de la dite surface.The method can be characterized in that the plasma contains reactive species capable of etching the surface of the substrate and in that step c) is continued until an etching of said surface is obtained.
En particulier, il peut être caractérisé en ce que la surface du plasma comporte une couche déposée et en ce que ladite gravure consiste à graver ladite couche déposée jusqu'à atteindre une couche sous-jacente ou le substrat proprement dit.In particular, it can be characterized in that the surface of the plasma comprises a deposited layer and in that said etching consists in etching said deposited layer until reaching an underlying layer or the substrate itself.
D'autres caractéristiques et avantages de l'invention apparaîtront à la lecture de la description ci-après, en liaison avec les dessins dans lesquels les figures 1a à 1f illustrent un exemple de mise en œuvre du procédé de l'invention pour réaliser localement des zones hydrophiles et hydrophobes.Other features and advantages of the invention will appear on reading the description below, in conjunction with the drawings in which FIGS. 1a to 1f illustrate an example of implementation of the invention. method of the invention for locally producing hydrophilic and hydrophobic zones.
Une application la présente invention concerne la possibilité de modifier localement l'énergie de surface d'un matériau par gravure localisée d'une monocouche hydrophobe déposée préalablement par un procédé par plasma. Un exemple d'application est décrit ci-après en s'appuyant sur la gravure localisée de la dite monocouche hydrophobe déposée préalablement par plasma sur un substrat recouvert d'un dépôt de cuivre, pour permettre la croissance localisée de motifs nanométriques en or par dépôt électrochimique.An application of the present invention relates to the possibility of locally modifying the surface energy of a material by localized etching of a hydrophobic monolayer previously deposited by a plasma method. An application example is described below by relying on the localized etching of said hydrophobic monolayer previously deposited by plasma on a substrate coated with a copper deposit, to allow the localized growth of nanometric gold patterns by deposition. electrochemical.
Une telle gravure localisée présente un intérêt important quant au développement de techniques alternatives de dépôt ou croissance sélective de métaux sur un substrat, ou encore sur la gravure localisée de motifs nanométriques dans un substrat. En particulier l'invention permet de s'affranchir des procédés connus et coûteux en temps qui combinent l'écriture par faisceau d'électronique sur une résine sensible aux électrons, le développement de la résine dans un révélateur chimique pour créer des ouvertures sur le substrat, le dépôt de métal sur la surface composée de motifs en résine et d'ouvertures sur le substrat, puis la gravure chimique de la résine pour ne laisser apparaître que le métal en contact avec le substrat (procédé lift-off).Such localized etching has a significant interest in the development of alternative techniques for deposition or selective growth of metals on a substrate, or on localized etching of nanometric patterns in a substrate. In particular, the invention makes it possible to dispense with the known and time-consuming methods that combine electron beam writing on an electron-sensitive resin, developing the resin in a chemical developer to create openings on the substrate. , the deposition of metal on the surface composed of resin patterns and openings on the substrate, then the chemical etching of the resin to reveal only the metal in contact with the substrate (lift-off process).
L'adhésion de produits biologiques (protéines, ADN, cellules...), ou encore la croissance par électrochimie, dépendent de l'énergie de surface d'un substrat. Notamment l'adhésion de molécules biologiques et la croissance électrochimique s'opèrent préférentiellement sur des surfaces hydrophiles. Il est donc intéressant de disposer d'une technique simple, rapide et fiable permettant de graver localement un substrat ou un film mince, notamment permettant de graver localement un film mince hydrophobe dépose sur un substrat initialement hydrophile, pour créer en conséquence une modification localisée de l'énergie de surface de ce substrat, en particulier a l'échelle nanométrique.The adhesion of biological products (proteins, DNA, cells ...), or the growth by electrochemistry, depend on the surface energy of a substrate. In particular, the adhesion of biological molecules and the electrochemical growth take place preferentially on hydrophilic surfaces. It is therefore advantageous to have a simple, fast and reliable technique for locally etching a substrate or a thin film, in particular for locally etching a hydrophobic thin film deposited on an initially hydrophilic substrate, so as to create a localized modification of the surface energy of this substrate, particularly at the nanoscale.
L'invention s'appuie sur la combinaison de la technique de gravure et de dépôt assistés par plasma, et de la technique d'impression par contact sur un substrat d'un tampon en polymère présentant une topographie de surface (dit micro-contact printing). Selon l'invention, des radicaux issus d'un plasma diffusent à travers un tampon en polymère présentant une topographie de surface et mis en contact avec un substrat, pour graver localement le substrat ou un film mince dépose sur ce substrat.The invention is based on the combination of the plasma assisted etching and deposition technique and the contact printing technique on a substrate of a polymer pad having a surface topography (called micro-contact printing). ). According to the invention, radicals derived from a plasma diffuse through a polymer buffer having a surface topography and contacted with a substrate, for etching the substrate locally or a thin film deposited on this substrate.
La technique d'impression par microcontact sur un substrat, d'un tampon en polymère présentant des motifs sur sa surface, est bien connue, en particulier pour déposer localement des molécules fixées initialement sur le tampon par trempage dans une solution chimique. Le trempage du tampon dans une solution chimique permet de recouvrir l'intégralité du tampon en polymère par des monocouches de solution chimique. En raison de la topographie de surface présente sur le tampon en polymère, lors du contact avec un substrat, les monocouches de solution chimique sont transférées sur le substrat depuis les motifs mis en contact avec le substrat. En particulier si la monocouche de solution chimique est hydrophobe, ce qui est le cas des monocouches a base d'OTS (orthotrimethylsiloxane) et de ses dérivés, il est alors possible de créer des motifs hydrophobes localement sur un substrat des lors qu'un tampon en polymère présentant une topographie de surface et préalablement imbibe d'OTS par trempage dans une solution chimique, est mis en contact avec le dit substrat.The microcontact printing technique on a substrate, a polymer pad having patterns on its surface, is well known, in particular for locally depositing molecules initially fixed on the pad by soaking in a chemical solution. Soaking the buffer in a chemical solution makes it possible to cover the entire polymer buffer with monolayers of chemical solution. Due to the surface topography present on the polymer pad, upon contact with a substrate, the chemical solution monolayers are transferred to the substrate from the patterns contacted with the substrate. In particular, if the monolayer of chemical solution is hydrophobic, which is the case of monolayers based on OTS (orthotrimethylsiloxane) and its derivatives, it is then possible to create hydrophobic units locally on a substrate when a buffer in polymer having a surface topography and pre-soaked with OTS by soaking in a chemical solution, is brought into contact with said substrate.
L'invention repose sur une combinaison originale de la technique d'impression par contact (connue sous la dénomination anglaise de "micro-contact printing") et de gravure de surface par plasma froid.The invention is based on an original combination of the contact printing technique (known as "micro-contact printing") and cold plasma surface etching.
Un film mince de polymère présentant des motifs en trois dimensions sur l'une des faces (appelé tampon en polymère), est mis en contact avec un substrat de sorte que les motifs présents sur le tampon soient en contact avec le substrat. L'ensemble est placé dans un plasma froid. Les espèces (radicaux, ions, atomes ...) produites par le plasma diffusent a travers le tampon jusqu'au substrat via les zones de contact définie par les motifs du tampon en polymère.A thin polymer film having three-dimensional patterns on one of the faces (called a polymer pad) is contacted with a substrate such that the patterns on the pad are in contact with the substrate. The whole is placed in a cold plasma. The species (radicals, ions, atoms, etc.) produced by the plasma diffuse through the buffer to the substrate via the contact zones defined by the patterns of the polymer buffer.
Lorsque les radicaux issus du plasma atteignent le substrat localement, il se produit une gravure localisée du substrat et/ou une modification de l'énergie de surface qui dépend de la nature du gaz utilisé dans le plasma et de la nature du substrat ou du film mince éventuellement déposé sur le substrat. Les gaz utilisés dans le plasma sont choisis de sorte qu'une réaction chimique se produise entre les radicaux du plasma et le substrat, pour générer une gravure du substrat. Une application de l'invention concerne la modification localisée de l'énergie de surface d'un substrat. Un film mince hydrophobe est déposé par plasma sur toute la surface d'un substrat initialement hydrophile, par exemple un substrat à base de Siθ2 ou tout autre matériau dont la surface est hydrophile. Le dépôt par plasma d'un film mince hydrophobe uniformément sur toute la surface du substrat hydrophile peut être facilement obtenu a partir de gaz carbofluoré de type C4F8 ou CHF3 (sans se limiter toutefois à ces seuls types de gaz carbofluorés). Le tampon en polymère est mis en contact avec le substrat comportant un film mince hydrophobe de sorte que les motifs présents sur le tampon soient mis en contact avec le film mince hydrophobe présent sur la surface du substrat. Les motifs du tampon ne sont pas débouchants, et la totalité de la surface du substrat peut être recouverte par le tampon en polymère. Un plasma à base d'oxygène permet de graver un film mince hydrophobe déposé par plasma sur un substrat à partir de gaz carbofluorés. L'ensemble est soumis à un plasma à base d'oxygène par exemple, de sorte que les radicaux issus du plasma diffusent à travers le tampon jusqu'à atteindre le film mince hydrophobe préalablement déposé sur le substrat. Il devient possible de créer localement sur un substrat des zones hydrophobes et hydrophiles définies par les motifs du tampon en polymère mis en contact avec le substrat et soumis à un plasma froid.When the radicals from the plasma reach the substrate locally, localized etching of the substrate and / or a modification of the surface energy which depends on the nature of the gas used in the plasma and the nature of the substrate or film thin possibly deposited on the substrate. The gases used in the plasma are chosen so that a chemical reaction occurs between the radicals of the plasma and the substrate, to generate an etching of the substrate. An application of the invention relates to the localized modification of the surface energy of a substrate. A hydrophobic thin film is deposited by plasma over the entire surface of an initially hydrophilic substrate, for example a substrate based on SiO 2 or any other material whose surface is hydrophilic. The plasma deposition of a hydrophobic thin film uniformly over the entire surface of the hydrophilic substrate can easily be obtained from carbofluorocarbon gas of the C4F8 or CHF3 type (without however being limited to these types of carbofluorinated gas only). The polymer pad is contacted with the hydrophobic thin film substrate such that the patterns on the pad are contacted with the hydrophobic thin film on the surface of the substrate. The patterns of the pad are not open, and the entire surface of the substrate can be covered by the polymer pad. An oxygen based plasma is used to etch a plasma deposited hydrophobic thin film onto a substrate from carbofluorinated gases. The assembly is subjected to an oxygen-based plasma for example, so that the radicals from the plasma diffuse through the buffer until the hydrophobic thin film previously deposited on the substrate. It becomes possible to locally create on a substrate hydrophobic and hydrophilic zones defined by the patterns of the polymer buffer placed in contact with the substrate and subjected to a cold plasma.
Un procédé de réalisation du tampon en polymère présentant des motifs sur l'une de ses faces est décrit ci-après. Le tampon en polymère est obtenu par moulage d'un polymère sur un moule rigide. Le moule rigide comprend des motifs en trois dimensions sur l'une des faces. Les motifs en trois dimensions du moule peuvent être réalisés en deux étapes technologiques principales comprenant une technique de lithographie et une technique de gravure sans se limiter toutefois à la combinaison de ces deux seules techniques. La lithographie électronique, la photolithographie ou encore la nanoimpression sont les techniques les plus couramment utilisées pour générer des motifs dans une résine déposée sur un substrat (la résine est dite résine de masquage). Cette résine sert de masque à la gravure du substrat. La gravure du substrat peut être réalisée par voie humide, par trempage dans des solutions chimiques liquides, ou par voie sèche comme la gravure par plasma froid. Après gravure du substrat, la résine de masquage peut être éliminée par des techniques de nettoyage de surface, par voie liquide ou par voie sèche. Le tampon en polymère peut être obtenu par exemple à partir de polymères de type PDMS (polydiméthylsiloxane) déposés à la surface du moule comportant la topographie en 3 dimensions.A method of producing the polymer pad having patterns on one of its faces is described below. The polymer pad is obtained by molding a polymer on a rigid mold. The rigid mold comprises three-dimensional patterns on one of the faces. The three-dimensional patterns of the mold can be realized in two main technological steps including a lithography technique and an engraving technique without being limited to the combination of these two only techniques. Electronic lithography, photolithography or nanoimpression are the most commonly used techniques for generating patterns in a resin deposited on a substrate (the resin is called masking resin). This resin serves as a mask for the etching of the substrate. The etching of the substrate can be carried out wet, by dipping in liquid chemical solutions, or by dry process such as cold plasma etching. After etching the substrate, the masking resin can be removed by surface cleaning techniques, either liquid or dry. The polymer buffer may be obtained for example from PDMS (polydimethylsiloxane) type polymers deposited on the surface of the mold having the 3-dimensional topography.
Le polymère de type PDMS peut se présenter sous forme liquide (faible viscosité) pour épouser la forme des motifs présents sur le moule. Pour obtenir des motifs sur le tampon, il convient d'augmenter la viscosité du polymère en contact avec le moule, pour le rendre manipulable et transférable sur le substrat. Pour ce faire, il est possible d'ajouter un agent chimique favorisant la réticulation. La réticulation se produit en particulier lors d'un recuit thermique.The PDMS type polymer may be in liquid form (low viscosity) to match the shape of the patterns present on the mold. To obtain patterns on the pad, it is necessary to increase the viscosity of the polymer in contact with the mold, to make it manipulable and transferable to the substrate. To do this, it is possible to add a chemical agent promoting crosslinking. Crosslinking occurs especially during thermal annealing.
Le procédé de réticulation du tampon en polymère dépend alors des propriétés de l'agent chimique utilisé et des conditions de recuit. Par exemple, un polymère liquide à base de polydiméthylsiloxane ou PDMS (Dow Corning Sylgard 184) peut être réticulé par ajout d'un agent chimique à base de tetraméthyltetravinylcyclotetrasiloxane (Société Dow Corning 'Sylgard 184 curing agent'), qui par traitement par chauffage, permet d'augmenter considérablement la viscosité du mélange pour obtenir un film mince et souple au moins partiellement réticulé permettant que les motifs du tampon conservent leur dimension lorsqu'ils sont mis en contact avec le substrat.The method of crosslinking the polymer buffer then depends on the properties of the chemical agent used and the annealing conditions. For example, a liquid polymer based on polydimethylsiloxane or PDMS (Dow Corning Sylgard 184) can be crosslinked by adding a chemical agent based on tetramethyltetravinylcyclotetrasiloxane (Dow Corning Company 'Sylgard 184 curing agent'), which by heat treatment, significantly increases the viscosity of the mixture to obtain a thin and flexible at least partially crosslinked film allowing the patterns of the buffer retain their dimension when they are brought into contact with the substrate.
La réalisation d'un tampon souple à partir de polymère de type PDMS est connue dans les domaines de la microfluidique et des micro- nano-bio-technologies.The production of a flexible buffer from PDMS-type polymer is known in the fields of microfluidics and micronano-bio-technologies.
Le tampon en polymère est ensuite déposé sur un substrat de sorte que les motifs en relief présents sur la face structurée soient en contact avec le substrat. Cette opération s'apparente à la technique de microimpression par contact ('micro contact printing') sans utiliser d' « encre » moléculaire.The polymer pad is then deposited on a substrate so that the relief patterns present on the structured face are in contact with the substrate. This operation is similar to the micro contact printing technique (micro contact printing) without using a molecular "ink".
L'ensemble tampon souple / substrat est introduit dans un bâti de traitement par plasma. Le plasma est généré à partir de molécules de gaz ionisées à partir de sources capacitive (de type RIE par exemple) ou de sources de haute densité (de type ECR, hélicon ou ICP-RIE par exemple). En fonction du type de source plasma utilisée, les radicaux présents dans le plasma peuvent se présenter sous la forme d'ions, d'espèces neutres, d'atomes ou molécules excités et/ou partiellement ionisés. Dans le cas d'une source RIE, la tension d'autopolarisation permet la diffusion des radicaux vers le substrat, l'énergie et la densité des radicaux dépendent essentiellement de la pression et de la puissance du seul générateur utilisé pour générer le plasma. Dans le cas d'une source ICP-RIE, l'énergie des radicaux et la densité du plasma peuvent être ajustés séparément via deux générateurs de puissance.The soft buffer / substrate assembly is introduced into a plasma treatment frame. Plasma is generated from ionized gas molecules from capacitive sources (of the RIE type for example) or from high density sources (of the ECR, helicon or ICP-RIE type, for example). Depending on the type of plasma source used, the radicals present in the plasma may be in the form of ions, neutral species, atoms or molecules excited and / or partially ionized. In the case of a RIE source, the self-biasing voltage allows the diffusion of the radicals towards the substrate, the energy and the density of the radicals depend essentially on the pressure and power of the only generator used to generate the plasma. In the case of an ICP-RIE source, the energy of the radicals and the density of the plasma can be adjusted separately via two power generators.
Il a été mis en évidence par les inventeurs la possibilité que des radicaux du plasma, diffusant depuis la gaine vers le substrat polarisé, diffusent aussi à travers les chaînes polycarbonées du tampon en polymère jusqu'atteindre le substrat, alors que le plasma ne peut donc venir directement en contact avec le substrat en dehors des zones où les motifs sont en contact avec le substrat. Deux régions distinctes apparaissent après le traitement par plasma et sont observables par microscopie à force atomique, microscopie optique, microscopie électronique, ou par une technique de condensation de gouttelettes d'eau en utilisant un module Peltier pour refroidir la surface du substrat :It has been demonstrated by the inventors the possibility that radicals of the plasma, diffusing from the sheath to the polarized substrate, also diffuse through the polycarbonate chains of the polymer buffer to reach the substrate, whereas the plasma can not come into direct contact with the substrate outside the areas where the patterns are in contact with the substrate. Two distinct regions appear after the plasma treatment and are observable by atomic force microscopy, light microscopy, electron microscopy, or by a technique of condensation of water droplets using a Peltier module to cool the surface of the substrate:
- Région A - région ou les motifs ne sont pas en contact avec le substrat,- Region A - region where the patterns are not in contact with the substrate,
- Région B - région ou les motifs sont en contact avec le substrat.Region B - the region where the patterns are in contact with the substrate.
Pour éviter ledit contact direct, les motifs présents dans le tampon en PDMS ne sont par exemple pas débouchants aux extrémités du tampon. Le pourtour du tampon en PDMS est alors en contact avec le substrat.To avoid said direct contact, the patterns present in the PDMS buffer are, for example, not open at the ends of the buffer. The periphery of the PDMS buffer is then in contact with the substrate.
Après le traitement par plasma, le tampon est retiré manuellement du substrat. Les motifs présents sur le tampon en polymère (tampon mis en contact avec le substrat et soumis au traitement par plasma), sont alors reportés sur le substrat.After the plasma treatment, the buffer is manually removed from the substrate. The patterns present on the polymer buffer (buffer placed in contact with the substrate and subjected to plasma treatment) are then transferred to the substrate.
Le PDMS est un matériau particulièrement indiqué pour réaliser le tampon souple du fait de sa facilité de mise en œuvre et de son faible coût.PDMS is a material particularly suitable for producing the flexible pad because of its ease of implementation and its low cost.
Les radicaux créés par plasma froid peuvent être obtenus notamment à partir des gaz suivants : C4F8, CF4, CHF3, C2F6, SF611 N2, O2, Cl2, SiCI4, HDMS et/ou HDMSO.The radicals created by cold plasma can be obtained in particular from the following gases: C 4 F 8 , CF 4 , CHF 3 , C 2 F 6 , SF 611 N 2 , O 2 , Cl 2 , SiCl 4 , HDMS and / or HDMSO.
Le substrat peut présenter une énergie de surface initiale (intrinsèque dépendant de la nature du/des matériaux) et/ou être traité préalablement pour modifier uniformément l'énergie de surface sur toute la surface. L'énergie de surface d'un substrat peut être modifiée initialement par un traitement global de la surface d'un substrat, par exemple par trempage du substrat dans une solution chimique, ou encore par traitement en phase vapeur, ou encore par dépôt assisté par plasma froid, de sorte qu'un film mince recouvre toute la surface du substrat.The substrate may have an initial surface energy (intrinsic depending on the nature of the material) and / or be pretreated to uniformly modify the surface energy over the entire surface. The surface energy of a substrate can initially be modified by a global treatment of the surface of a substrate, for example by soaking the substrate in a chemical solution, or by vapor phase treatment, or by assisted deposition by cold plasma, so that a thin film covers the entire surface of the substrate.
Le substrat peut présenter avantageusement une énergie de surface intrinsèque de type hydrophile (faible angle de contact, typiquement inférieur à 10° pour une goutte d'eau Dl à 200C), hydrophobe (fort angle de contact, typiquement supérieur à 90° pour une goutte d'eau Dl à 200C). Des substrats ayant une énergie de surface intermédiaire (typiquement comprise entre 10° et 90° pour une goutte d'eau Dl à 200C) peuvent être mis en œuvre dans le cadre de la présente invention. Les substrats peuvent être par exemple du silicium, du verre, du plastique, du métal, ou bien tout type de film mince déposé sur un substrat par des techniques d'évaporation, de pulvérisation, de dépôt assisté par plasma, de dépôt par pulvérisation, de dépôt par centrifugation ("spin coating") ou de dépôt par jet d'encre, ...The substrate may advantageously have an intrinsic surface energy of hydrophilic type (low contact angle, typically less than 10 ° for a drop of water D1 at 20 ° C.), hydrophobic (high contact angle, typically greater than 90 ° for a drop of water DI at 20 0 C). Substrates having an intermediate surface energy (typically between 10 ° and 90 ° for a drop of water D1 at 20 ° C.) can be used in the context of the present invention. The substrates may be, for example, silicon, glass, plastic, metal, or any type of thin film deposited on a substrate by evaporation, sputtering, plasma assisted deposition, spray deposition techniques, deposition by centrifugation ("spin coating") or deposition by ink jet, ...
Un traitement hydrophile peut être obtenu par exemple à partir d'un plasma à base d'oxygène, d'HMDSO ou d'HMDS, ou bien encore par traitement en phase vapeur d'HMDS dans une enceinte par exemple de type YES-3TA ou YES-5TA de la Société Yield Engineering Inc.A hydrophilic treatment may be obtained for example from an oxygen-based plasma, HMDSO or HMDS, or else by vapor phase treatment of HMDS in an enclosure, for example of the YES-3TA type or YES-5TA from Yield Engineering Inc.
Un plasma d'oxygène est couramment utilisé pour éliminer des résidus organiques de type polymère, en particulier dans le cas des polymères utilisés dans un procédé de structuration de surface comme la photolithographie, d'écriture par faisceau d'électrons, ou la nanoimpression.An oxygen plasma is commonly used to remove polymer-type organic residues, particularly in the case of polymers used in a surface patterning process such as photolithography, electron beam writing, or nanoimprinting.
Le plasma d'oxygène est aussi utilisé pour favoriser l'adhésion de polymères de type PDMS sur un substrat, en particulier pour modifier l'énergie de surface du PDMS par oxydation de sa surface induite par le traitement par plasma oxygène. Le PDMS ainsi traité, présente une surface hydrophile qui améliore son adhésion avec un autre polymère (qui peut être aussi du PDMS) ou un substrat, lors de la mise en contact du polymère en PDMS avec le substrat. Une autre technique pour améliorer l'adhésion de deux films en PDMS (sous la terminologie anglaise bonding) consiste à mettre en contact les deux films de PDMS, puis à soumettre l'ensemble à un plasma oxygène : dans ce dernier cas, l'adhésion des deux films est fortement établie si bien que les deux films ne peuvent être séparés. Ces deux techniques sont fréquemment utilisées dans le domaine des micro-nano-biotechnologies, notamment pour des applications en microfluidique. Un traitement hydrophobe sur toute la surface du substrat peut être obtenu par dépôt de polymères (notamment PTFE) par plasma par exemple à partir de gaz carbofluorés de type C4F8 ou CHF3 couramment utilisé dans les procédés de plasma froid. En fonction du temps de résidence de radicaux issus du plasma, qui dépend principalement de la pression et du/des débits de gaz introduits dans l'enceinte d'une machine adaptée a la génération de plasma froid, il est possible de graver une substrat ou bien de déposer quelques monocouches de polymères notamment des couches à base de CxFy (notamment C2F2) qui ont la propriété de rendre hydrophobe la surface d'un substrat. Les radicaux à base de CxFy sont générés dans un plasma en utilisant par exemple des gaz carbofluorés de type CHF3 ou C4F8. Le temps de résidence peut être calculé avec la formule donnée dans le brevet US6749763 (IMAI). Il est par exemple compris entre 1 milliseconde et quelques secondes, par exemple 5 secondes.The oxygen plasma is also used to promote the adhesion of PDMS-type polymers to a substrate, in particular to modify the surface energy of the PDMS by oxidation of its surface induced by the oxygen plasma treatment. The PDMS thus treated has a hydrophilic surface which improves its adhesion with another polymer (which may also be PDMS) or a substrate, when the PDMS polymer is brought into contact with the substrate. Another technique for improving the adhesion of two PDMS films (in the English bonding terminology) consists in bringing the two PDMS films into contact, then submitting the assembly to an oxygen plasma: in the latter case, the adhesion Both films are firmly established so that the two films can not be separated. These two techniques are frequently used in the field of micro-nano-biotechnologies, particularly for microfluidic applications. Hydrophobic treatment over the entire surface of the substrate can be obtained by deposition of polymers (especially PTFE) by plasma for example from carbofluorinated gas type C 4 F 8 or CHF 3 commonly used in cold plasma processes. As a function of the residence time of radicals originating from the plasma, which depends mainly on the pressure and / or the gas flow rates introduced into the chamber of a machine adapted to the cold plasma generation, it is possible to etch a substrate or it is well to deposit some monolayers of polymers, in particular layers based on C x F y (in particular C 2 F 2 ) which have the property of rendering the surface of a substrate hydrophobic. The radicals based on C x F y are generated in a plasma using, for example, carbofluorinated gases of the CHF 3 or C 4 F 8 type . The residence time can be calculated with the formula given in US6749763 (IMAI). It is for example between 1 millisecond and a few seconds, for example 5 seconds.
D'autres polymères que le PDMS peuvent être mis en œuvre.Other polymers than PDMS can be implemented.
C'est ainsi qu'à part le PDMS, des polymères silicone tels que mentionnés dans l'article de S.G. CHARATI et S.A. STERN "Diffusion of Gases in silicone Polymers : Molecular Dynamics Simulations" publié dans Macromolecules, 1998, 31 , p. 5529 à 5535, à savoir le poly- propylméthylsiloxane (PPMS), le poly-trifluoropropyl-méthylsiloxane (PTFPMS) et le polyphénylméthylsiloxane (PPhMS), peuvent également convenir pour la mise en œuvre de l'invention.Thus, apart from PDMS, silicone polymers as mentioned in the article by S. G. CHARATI and S. A. STERN "Diffusion of Gases in Silicone Polymers: Molecular Dynamics Simulations" published in Macromolecules, 1998, 31, p. 5529 to 5535, namely poly-propylmethylsiloxane (PPMS), poly-trifluoropropyl-methylsiloxane (PTFPMS) and polyphenylmethylsiloxane (PPhMS), may also be suitable for the practice of the invention.
L'article de P. TIEMBLO et Collaborateurs "Gas transport properties of crown-ether methacrylic polymers : poly(1 , 4, 7, 10- tetraoxacyclododecan-2-yl) methyl methacrylate" paru dans Polymer 44 (2003), p. 6773-6780, propose (Tableau 4) en particulier le polychloroprène, le PTEMA, le polybutadiène (cis), le polyisoprène.The article by P. TIEMBLO et al. "Gas transport properties of crown-ether methacrylic polymers: poly (1,4,7,10-tetraoxacyclododecan-2-yl) methyl methacrylate" published in Polymer 44 (2003), p. 6773-6780, proposes (Table 4) in particular polychloroprene, PTEMA, polybutadiene (cis), polyisoprene.
Des films de polymères phosphazène mentionnés dans l'article de TAKUJI HIROSE et Collaborateurs "Gas Transport in Poly[bis(trifluoroethoxy) phosphazène)] - Journal of Applied Polymer Science, Vol. 38, p. 809-820 (1989) - présentent une bonne perméabilité aux gaz, notamment N2 et O2, plus particulièrement en ce qui concerne le PTFEP.Phosphazene polymer films mentioned in the article by TAKUJI HIROSE et al., "Gas Transport in Poly [bis (trifluoroethoxy) phosphazene)" - Journal of Applied Polymer Science, Vol 38, pp. 809-820 (1989) - disclose good gas permeability, especially N 2 and O 2 , more particularly with respect to PTFEP.
Il est également possible d'utiliser des films de polyacétylène tels que ceux mentionnés dans l'article de KOICHI TAKADA et Collaborateurs "Gas Permeability of Polyacetylenes Carrying Substituents) - Journal of Applied Polymer Science - Vol. 30, p. 1605 à 1616 (1985). Les figures 1a à 1f illustrent le procédé.It is also possible to use polyacetylene films such as those mentioned in the article by KOICHI TAKADA and collaborators "Gas Permeability of Polyacetylenes Carrying Substituents" - Journal of Applied Polymer Science - Vol 30, pp. 1605-1616 (1985). ). Figures 1a to 1f illustrate the method.
A la figure 1a, une plaquette de silicium "maître" 1 est fabriquée par lithographie (par faisceau d'électrons ou photolithographie) suivie d'une gravure en phase sèche ou humide pour obtenir les motifs en creux et relief désirés sur une profondeur qui est par exemple de 100 nm environ.In FIG. 1a, a "master" silicon wafer 1 is manufactured by lithography (by electron beam or photolithography) followed by dry or wet phase etching to obtain the desired hollow and relief patterns on a depth which is for example about 100 nm.
Le photorésist est ensuite enlevé par une attaque en phase sèche ou humide.The photoresist is then removed by a dry or wet phase attack.
A la figure 1b, une couche de polymère 2 par exemple PDMS est déposée sur la plaquette de silicium 1. L'ensemble est chauffé dans un four pour obtenir une réticulation au moins partielle du polymère.In FIG. 1b, a polymer layer 2, for example PDMS, is deposited on the silicon wafer 1. The assembly is heated in an oven to obtain at least partial crosslinking of the polymer.
A la figure 1c, le tampon 2' de polymère au moins partiellement réticulé est démoulé et les motifs en relief 3 de la face 4 de la plaquette "maître" 1 sont reproduits en négatif 5 dans la face 6 du tampon 2'.In FIG. 1c, the buffer 2 'of at least partially crosslinked polymer is demolded and the raised patterns 3 of the face 4 of the "master" wafer 1 are reproduced in negative 5 in the face 6 of the buffer 2'.
La face 7 du tampon 2' non en contact avec la plaquette 1 est plane et la face 6 du tampon 2' présente une topographie 5 comportant des motifs nanométriques positifs (plots, lignes) qui est l'inverse des motifs 3 de la face 4 de la plaquette 1.The face 7 of the pad 2 'not in contact with the wafer 1 is flat and the face 6 of the pad 2' has a topography 5 comprising positive nanometric patterns (pads, lines) which is the reverse of the patterns 3 of the face 4 of the plate 1.
A la figure 1d, la face 6 du tampon 2' est appliquée sur la face 11 d'un substrat 10 qui a été traitée au préalable pour être hydrophile ou hydrophobe ou bien qui est par nature hydrophile ou hydrophobe.In FIG. 1d, the face 6 of the buffer 2 'is applied to the face 11 of a substrate 10 which has been previously treated to be hydrophilic or hydrophobic or which is hydrophilic or hydrophobic in nature.
A la figure 1e, l'ensemble, constitué par le tampon 2' et le substrat 10 appliqués l'un contre l'autre, est introduit dans une machine 20 à plasma ionique réactif de type à couplage par ions ICP - RIE ("Inductively Coupled Plasma - Reactive Ion Etching"), par exemple une machine Oméga 201 d'Aviza Technology équipée de deux sources radiofréquence à 13,56 MHz permettant de contrôler séparément la densité du plasma et l'énergie des radicaux. Elle y subit un traitement dans un plasma à haute densité contenant des molécules carbofluorées pour réaliser des motifs hydrophobes (sur une face 11 hydrophile) ou bien des molécules d'oxygène pour réaliser des motifs hydrophiles (sur une face 11 hydrophobe). Les espèces générées par ce plasma ne sont pas en contact direct avec le substrat, mais diffusent à travers le polymère jusqu'à l'interface avec le substrat 10 pour produire un traitement localisé aux zones de contact entre les motifs et la face 11. Après démoulage (figure 1f), des zones hydrophobes ou hydrophiles 12 sont présentes sur la face 11 , qui en dehors de ces zones, est respectivement hydrophile ou hydrophobe.In FIG. 1e, the assembly consisting of the buffer 2 'and the substrate 10 applied against each other is introduced into an ICP-RIE ion-coupling type reactive ion plasma machine ("Inductively Coupled Plasma - Reactive Ion Etching "), for example an Omega 201 Omega machine equipped with two 13.56 MHz radiofrequency sources to control separately the plasma density and the energy of the radicals. It undergoes a treatment in a high density plasma containing carbofluorinated molecules to achieve hydrophobic patterns (on a hydrophilic face 11) or oxygen molecules to achieve hydrophilic patterns (on a hydrophobic face 11). The species generated by this plasma are not in direct contact with the substrate, but diffuse through the polymer to the interface with the substrate 10 to produce localized treatment at the contact zones between the patterns and the face 11. After demolding (FIG. 1f), hydrophobic or hydrophilic zones 12 are present on the face 11, which outside of these zones is respectively hydrophilic or hydrophobic.
Les exemples ci-après permettent de mieux comprendre la mise en œuvre de l'invention.The examples below make it possible to better understand the implementation of the invention.
Etape 1 - Exemples de prétraitement d'un substrat par dépôt de film mince hvdrophobe par plasma :Step 1 - Examples of Pretreatment of a Substrate by Plasma Hydrophobic Thin Film Deposition:
Le dépôt de couche hydrophobe sur toute la surface d'un substrat peut être obtenu en utilisant une machine de gravure par plasma froid de type gravure reactive ionique par couplage inductif (ICP-RIE - Inductively Coupled Plasma Reactive Ion Etching) telle que la machine Oméga 201 de la société AVIZA- Technology. En introduisant dans l'enceinte de la machine ICP-RIE le gaz CHF3 avec un débit de 50 cm3/min, à une pression comprise entre 30mTorr et 50 mTorr et un couple de puissance source/support d'échantillon 500 W/20 W, le temps de résidence des radicaux ainsi génères est favorable au dépôt de polymère hydrophobe à base de CxFy. La composition du polymère hydrophobe a base de CxFy, à savoir les valeurs x et y, est mal identifiée dans la littérature. Il est parfois indiqué cette composition serait C2F2. Cependant ce type de dépôt de monocouche hydrophobe est très largement rependu en particulier dans les procédés de gravure profonde du silicium (Deep Reactive Ion Etching).The hydrophobic layer deposition on the entire surface of a substrate can be obtained by using an inductively coupled ionic reactive ion etching (ICP-RIE) type cold plasma etching machine such as the Omega machine. 201 from AVIZA-Technology. By introducing into the enclosure of the ICP-RIE machine the CHF 3 gas with a flow rate of 50 cm 3 / min, at a pressure of between 30mTorr and 50 mTorr and a source power torque / sample support 500 W / 20 W, the residence time of the radicals thus generated is favorable to the deposition of hydrophobic polymer based on C x F y . The composition of the hydrophobic polymer based on C x F y , namely the x and y values, is poorly identified in the literature. It is sometimes stated that this composition would be C2F2. However, this type of hydrophobic monolayer deposition is very widely used especially in deep silicon etching (Deep Reactive Ion Etching) processes.
Un autre exemple de dépôt de couche hydrophobe est couramment utilise dans les procédés de gravure profonde du silicium (Deep Reactive Ion Etching), qui font intervenir successivement un cycle de dépôt de polymère CxFx a partir du gaz C4F8 suivi d'un cycle de gravure du silicium a partir de gaz SF6/O2. Dans ce cas, le dépôt de polymère CxFy, est obtenu avec un débit de C4F8 par exemple compris entre 80 et 110 cm3/min, une pression comprise entre 10 et 20mTorr, et un couple de puissance source/support d'échantillon 600W/ OW. Il est important de noter que le dépôt de polymère hydrophobe CxFy obtenu dans le cas d'un plasma génère a partir de la dissociation du gaz C4F8 dans le champ électromagnétique induit par l'application d'une puissance radio-fréquence sur la source (coil), s'opère efficacement lorsque la puissance appliquée sur le support du substrat (bias) est nulle, soit OW. En d'autres termes, dans ces conditions, il n'y a pas de bombardement directionnel des radicaux vers le substrat puisque la puissance appliquée sur le support du substrat est nulle. Si la puissance appliquée sur le support du substrat est idéalement supérieure a 10W, typiquement de 5OW, le bombardement du substrat par les radicaux de type CxFy devient effectif, conduisant à un phénomène non plus de dépôt de couche hydrophobe, mais de gravure du substrat.Another example of hydrophobic layer deposition is commonly used in deep silicon etching (Deep Reactive Ion Etching) processes, which successively involve a C x F x polymer deposition cycle from the C 4 F 8 gas followed by a silicon etching cycle from SF6 / O2 gas. In this case, the polymer deposit C x F y is obtained with a flow rate of C 4 F 8 for example between 80 and 110 cm 3 / min, a pressure of between 10 and 20 mTorr, and a source / power torque. 600W / OW sample holder. It is important to note that the hydrophobic polymer deposit C x F y obtained in the case of a plasma generates from the dissociation of the C 4 F 8 gas in the electromagnetic field induced by the application of a radio frequency power. frequency on the source (coil), operates effectively when the power applied on the substrate support (bias) is zero, or OW. In other words, under these conditions, there is no directional bombardment of the radicals towards the substrate since the power applied to the support of the substrate is zero. If the power applied on the support of the substrate is ideally greater than 10W, typically 5OW, the bombardment of the substrate by the radicals of type C x F y becomes effective, leading to a phenomenon no longer deposition of hydrophobic layer, but etching of the substrate.
Etape 2 - Exemple de préparation du tampon en polymère.Step 2 - Example of preparation of the polymer buffer.
Le PDMS (Sylgard 184) est introduit dans un bêcher, puis le durcisseur (par exemple Sylgard Curing Agent) à une proportion massique d'environ 10%. L'ensemble est mélangé puis placé sous une cloche à vide pendant par exemple 5 minutes de façon a provoquer le dégazage de bulles d'air formées dans le mélange lors de l'homogénéisation du PDMS et de son agent durcisseur. Il convient d'utiliser ce mélange dégazé et homogène dans les quelques heures (et au plus tard un jour) suivant la préparation.The PDMS (Sylgard 184) is introduced into a beaker, then the hardener (for example Sylgard Curing Agent) at a mass proportion of about 10%. The mixture is mixed and then placed under a vacuum bell for, for example, 5 minutes in order to cause the degassing of air bubbles formed in the mixture during homogenization of the PDMS and its curing agent. This degassed and homogenous mixture should be used within a few hours (and at the latest one day) depending on the preparation.
Alternativement, le PDMS et son durcisseur sont mélangés sous vide et le mélange est conservé sous vide. Il existe de telles machines qui sont commercialisées par la Société DOPAG MICROMIX (Cham - Suisse). Ce type d'équipement permet de réduire la durée de préparation du PDMS en évitant les étapes de mélange et dégazage.Alternatively, the PDMS and its hardener are mixed under vacuum and the mixture is stored under vacuum. There are such machines that are marketed by DOPAG MICROMIX (Cham - Switzerland). This type of equipment makes it possible to reduce the preparation time of the PDMS by avoiding mixing and degassing steps.
Etape 3 - Exemple de remplissage d'un moule avec le mélange PDMS/durcisseurStep 3 - Example of filling a mold with the PDMS / hardener mixture
Le moule rigide comportant des motifs en trois dimensions sur l'une de ces faces, peut être fabriqué à partir d'un substrat en silicium sur lequel des motifs ont été reportés par la combinaison de techniques standard de lithographie et de gravure. Le moule rigide est défini comme étant une plaquette « maître ».The rigid mold having three-dimensional patterns on one of these faces, can be made from a silicon substrate on which patterns have been reported by the combination of standard lithography and etching techniques. The rigid mold is defined as a "master" wafer.
Si le mélange homogène PDMS/durcisseur est simplement versé sur la plaquette "maître", son épaisseur finale n'est pas contrôlée, mais ce n'est pas en pratique un inconvénient pour la réussite du procédé.If the homogeneous PDMS / hardener mixture is simply poured onto the "master" wafer, its final thickness is not controlled, but this is not in practice a disadvantage for the success of the process.
Pour une meilleure uniformité en épaisseur, il peut être étalé sur le substrat à l'aide d'une "tournette". Le procédé utilisant la « tournette » (sous la dénomination anglophone « spin coating ») met en œuvre une machine présentant un disque plan sur lequel est placé un substrat maintenu par aspiration en son centre. Un liquide est déposé sur le substrat manuellement, ou bien à l'aide d'une pipette ou d'un système automatisé. Le disque est mis en rotation. Selon la vitesse de rotation du disque, il est possible d'obtenir différentes épaisseurs du polymère). Suivant la vitesse de rotation, typiquement entre 500tr/min et 10000tr/min, de la "tournette", et la viscosité du polymère, il est possible d'obtenir des films très fins de PDMS jusqu'à 40μm d'épaisseur, mais qui nécessitent alors des précautions pour leur manipulation. C'est pourquoi une épaisseur de l'ordre d'un millimètre semble le compromis le plus avantageux.For a better uniformity in thickness, it can be spread on the substrate using a "spinette". The method using the "spinette" (under the English name "spin coating") implements a machine having a flat disk on which is placed a substrate held by suction in its center. A liquid is deposited on the substrate manually, or using a pipette or an automated system. The disc is rotated. Depending on the speed of rotation of the disc, it is possible to obtain different thicknesses of the polymer). Depending on the rotational speed, typically between 500 rpm and 10000 rpm, the "spin", and the viscosity of the polymer, it is possible to obtain very thin films of PDMS up to 40 μm thick, but which then require precautions for their handling. This is why a thickness of about one millimeter seems the most advantageous compromise.
Une fois le PDMS versé dans le moule, ou bien étalé sur le moule en utilisant la tournette pour en contrôler l'épaisseur finale, l'ensemble est placé dans un four ou sur une plaque chauffante de sorte que l'élévation de température induise la réticulation des monomères présents dans le PDMS par l'intermédiaire de l'agent durcisseur.Once the PDMS is poured into the mold, or spread on the mold using the spinner to control the final thickness, the assembly is placed in an oven or on a hot plate so that the temperature rise induces the crosslinking of the monomers present in the PDMS via the curing agent.
La cuisson du polymère PDMS versé ou étalé se poursuit pendant quelques heures (environ 3 à 4 heures) entre 500C et 800C, ou bien plus rapidement à des températures plus élevées, par exemple environ 10 mn à 15 mn à 110°C.The cooking of the poured or spread PDMS polymer is continued for a few hours (approximately 3 to 4 hours) between 50 ° C. and 80 ° C., or more rapidly at higher temperatures, for example about 10 minutes to 15 minutes at 110 ° C. vs.
Etape 4 - Exemple de mise en contact du tampon en PDMS avec le substrat :Step 4 - Example of bringing the PDMS buffer into contact with the substrate:
Après le traitement thermique de réticulation du PDMS sur le moule (plaquette « maître »), s'opère un démoulage manuel pour retirer le PDMS de la plaquette « maître ». Les plots et cavités présents initialement sur la plaquette « maître » sont transférés dans le PDMS en cavités et plots respectivement. Le PDMS comportant les motifs après démoulage est appelé tampon en PDMS et se présente sous la forme d'un film épais transparent. La face du tampon en PDMS comportant les motifs (cavités et trous par exemple) est mise manuellement en contact avec la surface du substrat à traiter en évitant d'introduire des bulles entre le tampon et le substrat.After the heat treatment of reticulation of the PDMS on the mold ("master" wafer), a manual demolding is carried out to remove the PDMS from the "master" wafer. The pads and cavities initially present on the "master" plate are transferred into the PDMS in cavities and pads respectively. The PDMS comprising the patterns after demolding is called a PDMS buffer and is in the form of a transparent thick film. The face of the PDMS buffer comprising the patterns (cavities and holes, for example) is placed manually in contact with the surface of the substrate to be treated, without introducing bubbles between the buffer and the substrate.
Etape 5 - Mise en évidence de l'effet obtenu lors du traitement par plasma de l'ensemble défini par le tampon mis en contact avec le substrat :Step 5 - Demonstration of the effect obtained during the plasma treatment of the assembly defined by the buffer placed in contact with the substrate:
Deux exemples sont donnés ci-après. Le premier exemple concerne la modification localisée de l'énergie de surface d'un substrat à partir d'un tampon en PDMS comportant des motifs micrométriques : dans ce cas, l'observation de l'effet produit est facilement et rapidement mis en évidence par microscopie optique. Le deuxième exemple vise à démontrer que l'effet décrit par l'invention, s'applique à l'échelle nanométrique. Dans ce cas, l'observation par microscopie optique ne peut par être concluante compte tenu du fait que la modification localisée de la surface du substrat s'opère sur des zones de dimensions nanométriques. Pour contourner cette difficulté, une technique de croissance de métaux par voie électrochimique est utilisée. Ce type de croissance s'opère favorablement sur un substrat hydrophile et conducteur. En revanche, la croissance s'opère plus difficilement une surface peu conductrice et hydrophobe.Two examples are given below. The first example relates to the localized modification of the surface energy of a substrate from a PDMS buffer comprising micrometric units: in this case, the observation of the effect produced is easily and rapidly demonstrated by optical microscopy. The second example aims to demonstrate that the effect described by the invention applies to the nanoscale. In this case, the observation by optical microscopy can not be conclusive considering the fact that the localized modification of the surface of the substrate takes place on areas of nanometric dimensions. To get around this difficulty, a Electrochemical metal growth technique is used. This type of growth works favorably on a hydrophilic and conductive substrate. On the other hand, the growth takes place more difficultly with a surface that is not very conductive and hydrophobic.
Exemple 1 - motifs micrométriquesExample 1 - Micrometric Patterns
Le substrat, qui est dans cet exemple une plaquette de silicium, est recouvert d'une couche de SiO2 de 200nm. La mesure d'angle de contact initial sur le substrat est de 9°, traduisant le caractère hydrophile habituel et intrinsèque à la couche de SiO2 recouvrant la surface du substrat.The substrate, which in this example is a silicon wafer, is covered with a layer of SiO 2 of 200 nm. The initial contact angle measurement on the substrate is 9 °, reflecting the usual hydrophilic character intrinsic to the SiO 2 layer covering the surface of the substrate.
Après traitement du substrat comme dans l'étape 1 , l'angle de contact est de 110°, traduisant le caractère hydrophobe de la couche de CxFy déposée par plasma. Les étapes 2, 3 et 4 sont identiques.After treatment of the substrate as in step 1, the contact angle is 110 °, reflecting the hydrophobic character of the plasma-deposited C x F y layer. Steps 2, 3 and 4 are identical.
Le substrat comprend donc une plaquette de silicium recouverte de SiO2 et d'un film mince hydrophobe de quelques nanomètres d'épaisseur. Le tampon en PDMS recouvre la totalité de la plaquette. L'ensemble est introduit dans la machine de gravure ICP-RIE par plasma Omega201 , pour soumettre la surface du tampon au plasma.The substrate therefore comprises a silicon wafer covered with SiO 2 and a hydrophobic thin film of a few nanometers in thickness. The PDMS buffer covers the entire wafer. The assembly is introduced into the Omega201 plasma ICP-RIE etching machine, to subject the surface of the plasma buffer.
De l'oxygène O2 est introduit dans l'enceinte avec un débit de 40 cm3/min. La pression est de 25mTorr. En appliquant une puissance radio- fréquence de 500W sur la source (c'est-à-dire sur la bobine entourant l'enceinte de la machine ICP-RIE), les molécules d'O2 sont dissociées en radicaux à base d'atome d'oxygène ionisé. En appliquant une puissance radio-fréquence de 1OW pendant 3 minutes sur le support du substrat, les radicaux sont attirés vers le substrat.Oxygen O 2 is introduced into the chamber with a flow rate of 40 cm 3 / min. The pressure is 25mTorr. By applying a radiofrequency power of 500W to the source (that is to say on the coil surrounding the enclosure of the ICP-RIE machine), the O 2 molecules are dissociated into atom-based radicals. of ionized oxygen. By applying a radio frequency power of 1OW for 3 minutes on the support of the substrate, the radicals are attracted to the substrate.
Dans la région A (non contact) définie précédemment, les radicaux ont diffusé à travers le PDMS jusqu'à atteindre la couche hydrophobe recouvrant le substrat, et se produit alors une gravure de la couche hydrophobe recouvrant le substrat. Par conséquent dans la région A (non contact), la couche de CxFy hydrophobe est gravée jusqu'atteindre la couche de SiO2 hydrophile.In region A (non-contact) defined above, the radicals diffused through the PDMS until reaching the hydrophobic layer covering the substrate, and then etching of the hydrophobic layer covering the substrate. Therefore in region A (non-contact), the layer of C x F y is hydrophobic engraved jusqu'atteindre the SiO 2 layer hydrophilic.
Dans la région B (contact) définie précédemment, les radicaux ont diffusé a travers le PDMS jusqu'à atteindre la couche hydrophobe recouvrant le substrat. Cependant aucune modification de l'angle de contact n'est observée dans cette région.In region B (contact) defined above, the radicals diffused through the PDMS until reaching the hydrophobic layer covering the substrate. However no change in the contact angle is observed in this region.
Lors du retrait du tampon en PDMS, le substrat est caractérisé optiquement. Le substrat traité est positionné sur une cellule Peltier reliée à un contrôleur de température dans la gamme 50C - 1000C. En refroidissant le substrat, se produit une condensation des gouttelettes d'eau présentes dans l'atmosphère.Upon removal of the PDMS buffer, the substrate is optically characterized. The treated substrate is positioned on a cell Peltier connected to a temperature controller in the range 5 0 C - 100 0 C. Cooling the substrate, condensation of water droplets present in the atmosphere.
Dans la région A (non contact), hydrophile, des gouttes d'eau micrométriques s'accumulent pour former des motifs identiques à ceux présents sur le tampon en PDMS.In the hydrophilic region A (non-contact), micrometric water drops accumulate to form patterns identical to those present on the PDMS buffer.
Dans la région B (contact), hydrophobe, aucune goutte d'eau ne peut se former.In region B (contact), hydrophobic, no drop of water can form.
D'une manière générale, il est possible de créer localement des régions hydrophiles à la surface d'un substrat initialement hydrophobe, dans la région A où les motifs du tampon en PDMS n'étaient pas en contact avec le substrat lors du traitement par plasma.In general, it is possible to locally create hydrophilic regions on the surface of an initially hydrophobic substrate in region A where the PDMS buffer patterns were not in contact with the substrate during plasma treatment. .
Exemple 2 - motifs micrométriquesExample 2 - Micrometric Patterns
Le substrat, qui est dans cet exemple une plaquette de silicium, est recouvert d'une couche de Siθ2 de 200nm d'épaisseur. La mesure d'angle de contact initial sur le substrat est de 9.6°, traduisant le caractère hydrophile habituel et intrinsèque à la couche de Siθ2 recouvrant la surface du substrat.The substrate, which is in this example a silicon wafer, is covered with a Siθ 2 layer of 200 nm thick. The initial contact angle measurement on the substrate is 9.6 °, reflecting the usual and intrinsic hydrophilicity to the SiO 2 layer covering the surface of the substrate.
Le substrat comprend donc une plaquette de silicium recouverte seulement de Siθ2 hydrophile. Les étapes 2, 3 et 4 sont identiques. L'étape 1 n'est pas utilisée pour cet exemple.The substrate therefore comprises a silicon wafer coated only with hydrophilic SiO 2 . Steps 2, 3 and 4 are identical. Step 1 is not used for this example.
Le tampon en PDMS recouvre la totalité de la plaquette. L'ensemble est introduit dans une machine de gravure ICP-RIE par plasma Omega201 , pour soumettre la surface du tampon au plasma.The PDMS buffer covers the entire wafer. The assembly is introduced into an Omega201 plasma ICP-RIE etching machine, to subject the surface of the plasma buffer.
Un mélange à base de C4F8/CHF3 est introduit dans l'enceinte avec des débits respectifs de 80 et 50 cm3/min. La pression est de 45mTorr. En appliquant une puissance radio-fréquence de 500W sur la source (c'est-à- dire sur la bobine entourant l'enceinte de la machine ICP-RIE), les molécules de CHF3 sont dissociées en radicaux CxFy ionisés. En appliquant une puissance radio-fréquence de 10W pendant 3 minutes sur le support du substrat, les radicaux CxFx sont attirés vers le substrat. Ces conditions favorisent le dépôt de monocouche hydrophobe.A mixture based on C 4 F 8 / CHF 3 is introduced into the chamber with flow rates of 80 and 50 cm 3 / min respectively. The pressure is 45mTorr. By applying a radio-frequency power of 500W on the source (ie on the coil surrounding the enclosure of the ICP-RIE machine), the molecules of CHF 3 are dissociated into C x F y ionized radicals. By applying a radio frequency power of 10W for 3 minutes on the support of the substrate, the radicals C x F x are attracted to the substrate. These conditions favor the deposition of hydrophobic monolayer.
Dans la région A (non contact) définie précédemment, les radicaux ont diffusé à travers le tampon en PDMS jusqu'à atteindre la couche hydrophile de SiO2 recouvrant le substrat. Dans la région B (contact) définie précédemment, les radicaux ont diffusé à travers le tampon en PDMS jusqu'à atteindre la couche hydrophile de Siθ2 recouvrant le substrat.In region A (non-contact) defined above, the radicals diffused through the PDMS buffer until reaching the hydrophilic layer of SiO 2 covering the substrate. In the region B (contact) defined above, the radicals diffused through the PDMS buffer until reaching the hydrophilic layer of SiO 2 covering the substrate.
Lors du retrait du tampon en PDMS, le substrat est caractérisé optiquement. Le substrat traité est positionné sur une cellule Peltier reliée a un contrôleur de température dans la gamme 50C - 1000C. En refroidissant le substrat, se produit une condensation des gouttelettes d'eau présentes dans l'atmosphère : des gouttelettes micrométriques se forment dans la région A (non contact). Par conséquent cette région est hydrophile malgré le traitement plasma. Dans la région B, aucune formation de gouttes d'eau n'est observée. Après traitement par plasma, la région B (contact) est devenue localement hydrophobe.Upon removal of the PDMS buffer, the substrate is optically characterized. The treated substrate is positioned on a Peltier cell connected to a temperature controller in the range 5 0 C - 100 0 C. Cooling the substrate, condensation of water droplets in the atmosphere occurs: micrometric droplets are form in region A (non contact). Therefore this region is hydrophilic despite the plasma treatment. In region B, no formation of drops of water is observed. After plasma treatment, the B region (contact) became locally hydrophobic.
Cet exemple démontre la possibilité offerte par l'invention de créer localement des régions hydrophobes à la surface d'un substrat initialement hydrophile, dans la région (B) ou les motifs du tampon en PDMS étaient en contact avec le substrat lors du traitement par plasma.This example demonstrates the possibility offered by the invention of locally creating hydrophobic regions on the surface of an initially hydrophilic substrate, in region (B) where the PDMS buffer motifs were in contact with the substrate during plasma treatment. .
Dans l'exemple 1 , la modification de l'énergie de surface dans la région A pourrait être due à la gravure de la monocouche hydrophobe de quelques nanomètres d'épaisseur (déposée sur la surface du substrat lors du prétraitement du substrat) lors du traitement par plasma O2 de l'ensemble substrat/tampon en PDMS. La région B, apparemment inchangée, pourrait avoir subi une modification de surface par migration de monomères issus du PDMS. Ces monomères, de faible masse moléculaire, ont été mis en évidence récemment dans le cas de la technique de d'impression par microcontact (microcontact printing) d'un tampon en PDMS avec une surface, voir l'article de Christophe Thibault, Childérick Séverac, Anne-Françoise Mingotaud, Christophe Vieu, and, Monique Mauzac, "Poly(dimethylsiloxane) Contamination in Microcontact Printing and Its Influence on Patterning Oligonucleotides", Langmuir 2007 23 (21), 10706-10714.In Example 1, the modification of the surface energy in the region A could be due to the etching of the hydrophobic monolayer of a few nanometers in thickness (deposited on the surface of the substrate during the pretreatment of the substrate) during the treatment by O 2 plasma of the substrate / PDMS buffer assembly. Region B, apparently unchanged, could have undergone surface modification by migration of monomers from PDMS. These monomers, of low molecular weight, have recently been demonstrated in the microcontact printing technique of a PDMS buffer with a surface, see the article by Christophe Thibault, Childérick Séverac , Anne-Françoise Mingotaud, Christophe Vieu, and Monique Mauzac, "Poly (dimethylsiloxane) Contamination in Microcontact Printing and Its Influence on Patterning Oligonucleotides ", Langmuir 2007 23 (21), 10706-10714.
Dans l'exemple 2, l'origine de la modification de l'énergie de surface dans la région B pourrait être aussi la migration de monomères issus du PDMS pendant le traitement par plasma entraînés par la diffusion des radicaux CxFy lors du traitement par plasma C4F8/CHF3 de l'ensemble substrat/tampon en PDMS. Dans la région A, il est possible qu'une gravure de quelques nanomètres de profondeur se soit produite dans la couche de Siθ2, et non sur la totalité de l'épaisseur initiale de SiO2. C'est pourquoi la région A conserve un caractère hydrophile dans ce cas.In Example 2, the origin of the modification of the surface energy in the B region could also be the migration of monomers resulting from the PDMS during the plasma treatment caused by the diffusion of the CxFy radicals during the C plasma treatment. 4 F 8 / CHF 3 of the PDMS buffer / substrate assembly. In region A, it is possible that an etching of a few nanometers in depth occurred in the SiO 2 layer, and not over the entire initial thickness of SiO 2 . This is why region A retains a hydrophilic character in this case.
Exemple 3 - croissance localisée de métal a l'échelle nanométrique.Example 3 - Localized metal growth at the nanoscale.
La croissance de métal par électrochimie procédé de la façon suivante. Un substrat en métal ou recouvert d'un film mince métallique servant d'électrode est plonge dans un bain contenant des ions métalliques du métal que l'on souhaite déposer sur le substrat par le procédé d'électrochimie. Dans le bain électrochimique, en appliquant un courant sur le substrat, les ions métalliques contenus dans la solution échangent des électrons avec la surface conductrice du substrat. Lors de cet échange de charges, les ions métalliques du métal que l'on souhaite déposer se transforment alors en atome métallique et se dépose à la surface du substrat.Metal growth by electrochemistry process as follows. A metal substrate or coated with a metal thin film serving as an electrode is immersed in a bath containing metal ions of the metal that it is desired to deposit on the substrate by the electrochemical process. In the electrochemical bath, by applying a current to the substrate, the metal ions contained in the solution exchange electrons with the conductive surface of the substrate. During this exchange of charges, the metal ions of the metal that it is desired to deposit then turn into a metal atom and deposit on the surface of the substrate.
Lorsqu'il n'y a pas de possibilité d'échange de charges entre la surface du substrat et la solution comportant les ions métalliques du métal que l'on souhaite déposer, la réaction électrochimique est alors limitée voire impossible.When there is no possibility of exchange of charges between the surface of the substrate and the solution comprising the metal ions of the metal which it is desired to deposit, the electrochemical reaction is then limited or even impossible.
Des motifs en résine photosensible peuvent être réalises sur le substrat conducteur pour masquer des zones sur la surface et limiter ainsi l'échange de charges lors du procédé de dépôt par électrochimie.Photosensitive resin patterns may be provided on the conductive substrate to mask areas on the surface and thereby limit charge exchange during the electrochemical deposition process.
L'invention démontre la possibilité de modifier localement l'énergie de surface d'un substrat conducteur pour limiter l'échange de charges entre le substrat conducteur et des ions métalliques lors d'un procédé de dépôt de métal par voie électrochimique.The invention demonstrates the possibility of locally modifying the surface energy of a conductive substrate to limit the exchange of charges between the conductive substrate and metal ions in an electrochemically deposition process.
Un dépôt d'or est réalisé sur une tranche de silicium de 4 pouces (10,2 cm), sur toute la surface (pleine plaque). L'épaisseur du dépôt n'a pas d'importance pour la démonstration. La tranche revêtue du film d'or est introduite dans une machine de gravure par plasma, et un dépôt décrit par l'exemple 1 est réalisé sur toute la surface (pleine plaque). L'angle de contact est de 101 ° (contre 86° initialement : sans traitement).A gold deposit is made on a 4 inch (10.2 cm) silicon wafer over the entire surface (full plate). The thickness of the deposit is not important for the demonstration. The wafer coated with the gold film is introduced into a plasma etching machine, and a deposit described by Example 1 is carried out on the entire surface (full plate). The contact angle is 101 ° (against 86 ° initially: without treatment).
La tranche est retirée de la machine.The wafer is removed from the machine.
Du PDMS (10% agent durcissant - recuit 100°C - 15 mn) est déposé sur une autre tranche de silicium comportant des motifs nanométriques réalisés par faisceau électronique puis gravure directe dans le silicium sur une profondeur de 100 nm environ. Lors du dépôt, le PDMS liquide épouse la forme des motifs gravés dans le silicium, et durcit lors du recuit. Le PDMS d'épaisseur proche de plusieurs millimètres est retiré du moule. Le dit PDMS est alors appelé "moule souple" et comporte des motifs nanométriques positifs (plots, lignes) sur l'une des faces.PDMS (10% curing agent - annealing 100 ° C - 15 min) is deposited on another silicon wafer comprising nanometric patterns made by electron beam and direct etching in silicon to a depth of about 100 nm. During the deposition, the liquid PDMS conforms to the shape of the patterns etched in the silicon, and hardens during annealing. The PDMS with a thickness close to several millimeters is removed from the mold. The said PDMS is then called "flexible mold" and has positive nanometric patterns (pads, lines) on one of the faces.
Le moule souple d'environ 3 cm de côté est déposé sur la tranche recouverte d'or et sur laquelle a été déposé quelques monocouches hydrophobes a base de CxFy pleine plaque (exemple 1 décrit précédemment). Les plots et lignes formant les motifs du tampon ne sont pas en contact avec la surface d'or recouverte des monocouches hydrophobes. Les bordures du moule souple sont en contact avec le substrat de sorte que les motifs présents dans le moule souple ne soient pas en contact avec le milieu extérieur (air).The flexible mold of about 3 cm side is deposited on the gold covered wafer and on which was deposited some hydrophobic monolayers based on full plate CxFy (Example 1 described above). The pads and lines forming the patterns of the buffer are not in contact with the gold surface covered with hydrophobic monolayers. The borders of the flexible mold are in contact with the substrate so that the patterns present in the flexible mold are not in contact with the external environment (air).
L'ensemble est réintroduit dans la machine de gravure et un plasma d'oxygène est appliqué pendant 3 minutes de façon à rendre hydrophiles les zones qui ne sont pas en contact. Par conséquent, dans la zone qui n'est pas recouverte par le PDMS, la surface est redevenue très hydrophile car le plasma d'oxygène grave la couche de CxFy initialement déposée par plasma (décrit dans l'exemple 1) pour mettre à nouveau l'or à nu (angle de contact impossible à mesurer, la goutte est parfaitement étalée). Dans la zone recouverte par le moule souple en PDMS, les zones hydrophobes du substrat en contact avec les motifs du moule souple restent hydrophobes sous l'action du plasma qui diffuse à travers le matériau du moule souple. Dans les zones recouvertes par le moule souple et qui ne sont pas en contact avec les monocouches hydrophobes du substrat du fait de la topographie du moule souple, l'énergie de surface est modifiée.The assembly is reintroduced into the etching machine and an oxygen plasma is applied for 3 minutes in order to render hydrophilic the areas that are not in contact. Therefore, in the zone which is not covered by the PDMS, the surface has become very hydrophilic again because the oxygen plasma etches the initially plasma-deposited CxFy layer (described in Example 1) to re-assemble the 'bare gold (contact angle impossible to measure, the drop is perfectly spread). In the zone covered by the flexible PDMS mold, the hydrophobic zones of the substrate in contact with the flexible mold patterns remain hydrophobic under the action of the plasma which diffuses through the flexible mold material. In the zones covered by the flexible mold and which are not in contact with the hydrophobic monolayers of the substrate due to the topography of the flexible mold, the surface energy is modified.
Pour vérifier que les zones de non contact entre le PDMS et l'or sont bien devenues hydrophiles, la tranche, après enlèvement du moule souple, est placée dans un bain électrochimique contenant des ions Cuivre. Sous l'action d'un courant électrique, le Cu se dépose préférentiellement sur la couche d'or hydrophile remise à nu, mais l'or recouvert d'une couche résiduelle hydrophobe est également recouvert d'un dépôt d'épaisseur plus réduite (car la présence de zones hydrophobes crées par l'invention inhibe ou limite l'échange d'électrons entre les ions cuivre et le film d'or recouvrant le substrat). L'inhibition totale ou partielle d'échange d'électrons entre le substrat et les ions métalliques conduit au dépôt sélectif de métal sur le substrat, ou du moins à une différence d'épaisseur de métal entre les zones initialement hydrophiles et hydrophobes du substrat. Dans tous les cas, le procédé conduit à un contracte d'image observable par microscopie électronique a balayage en raison de la différence de topographie entres ces différentes zones traitées localement par l'invention.To verify that the areas of non-contact between the PDMS and gold have become hydrophilic, the wafer, after removal of the mold flexible, is placed in an electrochemical bath containing copper ions. Under the action of an electric current, the Cu is preferentially deposited on the exposed hydrophilic gold layer, but the gold coated with a hydrophobic residual layer is also covered with a deposit of smaller thickness ( because the presence of hydrophobic zones created by the invention inhibits or limits the exchange of electrons between the copper ions and the gold film covering the substrate). Total or partial electron exchange inhibition between the substrate and the metal ions results in the selective deposition of metal on the substrate, or at least a difference in metal thickness between the initially hydrophilic and hydrophobic areas of the substrate. In all cases, the method leads to an observable image contraction by scanning electron microscopy because of the difference in topography between these different areas treated locally by the invention.
Plus généralement, si on dépose une couche de PTFE par plasma sur un substrat, puis si on met en contact avec cette couche le tampon en polymère comportant les motifs, alors en appliquant un plasma d'oxygène, il est possible de graver localement la fine couche de PTFE dans la région où les motifs ne sont pas en contact avec la surface du substrat et d'atteindre le substrat ou la couche déposée sur celui-ci.More generally, if a layer of PTFE is deposited by plasma on a substrate, then if this layer is put in contact with the polymer buffer comprising the patterns, then by applying an oxygen plasma, it is possible to locally etch the fine PTFE layer in the region where the patterns are not in contact with the surface of the substrate and reach the substrate or the layer deposited thereon.
Exemple 4 - gravure localisée d'un substrat.Example 4 - Localized etching of a substrate.
La gravure d'un substrat sur de faibles profondeurs (inférieures par exemple a 10nm) est généralement très difficile a contrôler par les techniques de gravure par plasma ICP-RIE ou RIE. De plus la gravure par plasma est connue pour générer des défauts dans les substrats en raison du bombardement direct de la surface par les radicaux issus du plasma. Les défauts induits par la gravure sèche sont rédhibitoires au bon fonctionnement des composants électroniques avances.The etching of a substrate at shallow depths (for example less than 10 nm) is generally very difficult to control by ICP-RIE or RIE plasma etching techniques. In addition plasma etching is known to generate defects in the substrates due to the direct bombardment of the surface by the radicals from the plasma. The defects induced by the dry etching are unacceptable to the good functioning of the advanced electronic components.
L'invention permet grâce à la diffusion à travers le substrat de réaliser la gravure localisée d'un substrat sur des profondeurs comprises entre quelques nanomètres et plusieurs dizaines de nanomètres en s'affranchissant du bombardement direct du substrat par les radicaux issus du plasma. La gravure localisée d'un substrat ne nécessite pas de techniques de lithographie et de gravure humide ou sèche sur le dit substrat.The invention makes it possible, thanks to the diffusion through the substrate, to perform the localized etching of a substrate at depths between a few nanometers and several tens of nanometers while avoiding the direct bombardment of the substrate by the radicals originating from the plasma. Localized etching of a substrate does not require lithography techniques and wet or dry etching on said substrate.
Dans ce cas, le tampon en PDMS comportant des motifs définis sur l'une de ces faces, est mis en contact avec un substrat, par exemple en silicium. L'ensemble est placé dans une machine de gravure par plasma. Les gaz réactifs sont choisis de sorte qu'une réaction chimique entre le substrat et les radicaux issus du plasma soit possible pour que le phénomène de gravure soit effectif. Le gaz SF6 est particulièrement indiqué pour graver un substrat de silicium.In this case, the PDMS buffer comprising patterns defined on one of these faces, is brought into contact with a substrate, for example silicon. The set is placed in an engraving machine by plasma. The reactive gases are chosen so that a chemical reaction between the substrate and the radicals originating from the plasma is possible so that the etching phenomenon is effective. SF6 gas is particularly suitable for engraving a silicon substrate.
Apres démoulage du tampon, on observe alors optiquement l'apparition de motifs gravés dans le silicium. Le plasma ou les espèces réactives du plasma ont traversé le tampon pour atteindre localement le substrat là où les motifs ne sont pas en contact avec celui-ci et ont gravé le substrat localement. Dans les zones de contact entre le tampon et le substrat, la gravure n'est pas observée.After demolding the buffer, the appearance of patterns etched in the silicon is optically observed. The plasma or reactive species of the plasma have passed through the buffer to locally reach the substrate where the patterns are not in contact with it and etched the substrate locally. In the areas of contact between the buffer and the substrate, the etching is not observed.
Il est préférable que la hauteur des motifs du tampon soit supérieure (ou éventuellement égale) à la largeur minimale des motifs, ou en d'autres termes que le facteur d'aspect hauteur/largeur des motifs du tampon soit supérieur (ou éventuellement égal) à 1. It is preferable that the height of the patterns of the stamp is greater (or possibly equal) to the minimum width of the patterns, or in other words that the aspect ratio of the height / width of the patterns of the stamp is greater (or possibly equal) to 1.

Claims

REVENDICATIONS
1) Procédé de gravure localisée d'une surface d'un substrat caractérisé en ce qu'il met en oeuvre : a) réaliser un tampon en polymère perméable aux gaz qui comporte des motifs en relief sur l'une de ces faces ; b) mettre en contact la face comportant les motifs du tampon avec le substrat ; c) soumettre l'ensemble tampon/substrat à un plasma de sorte que des espèces présentes dans le plasma sont accélérées et diffusent à travers le tampon jusqu'atteindre le substrat.1) A method of localized etching of a surface of a substrate characterized in that it implements: a) producing a gas permeable polymer pad which has patterns in relief on one of these faces; b) contacting the face comprising the patterns of the buffer with the substrate; c) subjecting the buffer / substrate assembly to a plasma so that species present in the plasma are accelerated and diffuse through the buffer to reach the substrate.
2) Procédé selon la revendication 1 , caractérisé en ce que ledit polymère en un polymère organique.2) Process according to claim 1, characterized in that said polymer into an organic polymer.
3) Procédé selon la revendication 2, caractérisé en ce que ledit polymère présente des monomères libres ou en liaison avec d'autres monomères.3) Process according to claim 2, characterized in that said polymer has free monomers or in combination with other monomers.
4) Procédé selon la revendication 2, caractérisé en ce que le polymère est du polydiméthylsiloxane (PDMS).4) Process according to claim 2, characterized in that the polymer is polydimethylsiloxane (PDMS).
5) Procédé selon la revendication 2, caractérisé en ce que le polymère est à base de polydiméthylmétacrylate (PDMA).5) Process according to claim 2, characterized in that the polymer is based on polydimethylmetacrylate (PDMA).
6) Procédé selon une des revendications 2 à 5, caractérisé en ce que le polymère auquel est ajouté un agent réticulant est soumis lors de l'étape b, à un recuit assurant une réticulation au moins partielle.6) Method according to one of claims 2 to 5, characterized in that the polymer which is added a crosslinking agent is subjected in step b, an annealing ensuring at least partial crosslinking.
7) Procédé selon une des revendications précédentes, caractérisé en ce que le tampon à une épaisseur entre 40μ et 3 mm, et plus particulièrement entre 100μ et 1 mm.7) Method according to one of the preceding claims, characterized in that the buffer has a thickness between 40μ and 3 mm, and more particularly between 100μ and 1 mm.
8) Procédé selon une des revendications précédentes, caractérisé en ce que le substrat est en Si ou à base de Si, par exemple nitrure, oxynitrure, en verre, ou bien encore en métal.8) Method according to one of the preceding claims, characterized in that the substrate is Si or Si-based, for example nitride, oxynitride, glass, or even metal.
9) Procédé selon une des revendications précédentes, caractérisé en ce que le substrat comporte un film mince sur sa surface, notamment une couche d'or.9) Method according to one of the preceding claims, characterized in that the substrate comprises a thin film on its surface, in particular a layer of gold.
10) Procédé selon une des revendications précédentes, caractérisé en ce que le plasma comporte au moins un des gaz suivants : C4F8, CF4, SF6, N2, O2, Cl2, CHF3, HDMS et/ou HMDSO. 11) Procédé selon une des revendications 1 à 9, caractérisé en ce que le plasma est à base d'oxygène, notamment pour créer des zones hydrophiles, graver un matériau à base de polymère ou une couche de PTFE.10) Method according to one of the preceding claims, characterized in that the plasma comprises at least one of the following gases: C 4 F 8 , CF 4 , SF 6 , N 2 , O 2 , Cl 2 , CHF 3 , HDMS and / or HMDSO. 11) Method according to one of claims 1 to 9, characterized in that the plasma is based on oxygen, in particular to create hydrophilic areas, etch a polymer-based material or a PTFE layer.
12) Procédé selon une des revendications 1 à 9, caractérisé en ce que le plasma est à base d'un gaz carbofluoré pour créer des- zones hydrophobes.12) Method according to one of claims 1 to 9, characterized in that the plasma is based on a carbofluorinated gas to create hydrophobic zones.
13) Procédé selon une des revendications précédentes, caractérisé en ce que le plasma contient des espèces réactives aptes à graver la surface du substrat et en ce que l'étape c) est poursuivie jusqu'à l'obtention d'une gravure de la dite surface.13) Method according to one of the preceding claims, characterized in that the plasma contains reactive species capable of etching the surface of the substrate and in that step c) is continued until an etching of the said area.
14) Procédé selon la revendication 13, caractérisé en ce que la surface du substrat comporte une couche hydrophobe déposée et en ce que ladite gravure consiste à graver ladite couche déposée jusqu'à atteindre une couche sous-jacente ou le substrat proprement dit. 14) Method according to claim 13, characterized in that the surface of the substrate comprises a hydrophobic layer deposited and in that said etching consists of etching said deposited layer until reaching an underlying layer or the substrate itself.
EP08872521A 2008-01-03 2008-12-23 Method for local etching of the surface of a substrate Withdrawn EP2232532A2 (en)

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FR0800035A FR2926162B1 (en) 2008-01-03 2008-01-03 METHOD FOR LOCALLY CHANGING THE SURFACE ENERGY OF A SUBSTRATE
PCT/FR2008/001820 WO2009103907A2 (en) 2008-01-03 2008-12-23 Method for local etching of the surface of a substrate

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