Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
  • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
  • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
  • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
  • H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
  • H01L21/31—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to form insulating layers thereon, e.g. for masking or by using photolithographic techniques; After treatment of these layers; Selection of materials for these layers
  • H01L21/3105—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 potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
  • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
  • H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
  • H01L21/302—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 potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
  • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
  • H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
  • H01L21/302—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 potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
  • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
  • H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
  • H01L21/31—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to form insulating layers thereon, e.g. for masking or by using photolithographic techniques; After treatment of these layers; Selection of materials for these layers
  • H01L21/3105—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 potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
  • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
  • H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
  • H01L21/31—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to form insulating layers thereon, e.g. for masking or by using photolithographic techniques; After treatment of these layers; Selection of materials for these layers
  • H01L21/3105—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 potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
  • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
  • H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
  • H01L21/31—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to form insulating layers thereon, e.g. for masking or by using photolithographic techniques; After treatment of these layers; Selection of materials for these layers
  • H01L21/3105—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.

Landscapes

• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Manufacturing & Machinery (AREA)
• General Physics & Mathematics (AREA)
• Condensed Matter Physics & Semiconductors (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Computer Hardware Design (AREA)
• Power Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Nanotechnology (AREA)
• Crystallography & Structural Chemistry (AREA)
• Plasma & Fusion (AREA)
• Inorganic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Mathematical Physics (AREA)
• Theoretical Computer Science (AREA)
• Health & Medical Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• General Health & Medical Sciences (AREA)
• Molecular Biology (AREA)
• Treatments Of Macromolecular Shaped Articles (AREA)
• Drying Of Semiconductors (AREA)
• Micromachines (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=39689404

Family Applications (1)

Country Status (5)

Families Citing this family (9)

Family Cites Families (5)

• 2008
  • 2008-01-03 FR FR0800035A patent/FR2926162B1/fr not_active Expired - Fee Related
  • 2008-12-23 WO PCT/FR2008/001820 patent/WO2009103907A2/fr active Application Filing
  • 2008-12-23 JP JP2010541081A patent/JP5715421B2/ja not_active Expired - Fee Related
  • 2008-12-23 US US12/811,467 patent/US8475671B2/en not_active Expired - Fee Related
  • 2008-12-23 EP EP08872521A patent/EP2232532A2/fr not_active Withdrawn

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events