Classifications

• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
  • C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
  • C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
  • C23C18/18—Pretreatment of the material to be coated
  • C23C18/1803—Pretreatment of the material to be coated of metallic material surfaces or of a non-specific material surfaces
  • C23C18/1824—Pretreatment of the material to be coated of metallic material surfaces or of a non-specific material surfaces by chemical pretreatment
  • C23C18/1837—Multistep pretreatment
  • C23C18/1844—Multistep pretreatment with use of organic or inorganic compounds other than metals, first
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
  • C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
  • C23C18/1601—Process or apparatus
  • C23C18/1603—Process or apparatus coating on selected surface areas
  • C23C18/1607—Process or apparatus coating on selected surface areas by direct patterning
  • C23C18/1608—Process or apparatus coating on selected surface areas by direct patterning from pretreatment step, i.e. selective pre-treatment
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
  • C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
  • C23C18/18—Pretreatment of the material to be coated
  • C23C18/1803—Pretreatment of the material to be coated of metallic material surfaces or of a non-specific material surfaces
  • C23C18/1824—Pretreatment of the material to be coated of metallic material surfaces or of a non-specific material surfaces by chemical pretreatment
  • C23C18/1827—Pretreatment of the material to be coated of metallic material surfaces or of a non-specific material surfaces by chemical pretreatment only one step pretreatment
  • C23C18/1834—Use of organic or inorganic compounds other than metals, e.g. activation, sensitisation with polymers
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
  • C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
  • C23C18/18—Pretreatment of the material to be coated
  • C23C18/1851—Pretreatment of the material to be coated of surfaces of non-metallic or semiconducting in organic material
  • C23C18/1872—Pretreatment of the material to be coated of surfaces of non-metallic or semiconducting in organic material by chemical pretreatment
  • C23C18/1875—Pretreatment of the material to be coated of surfaces of non-metallic or semiconducting in organic material by chemical pretreatment only one step pretreatment
  • C23C18/1882—Use of organic or inorganic compounds other than metals, e.g. activation, sensitisation with polymers
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
  • C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
  • C23C18/18—Pretreatment of the material to be coated
  • C23C18/1851—Pretreatment of the material to be coated of surfaces of non-metallic or semiconducting in organic material
  • C23C18/1872—Pretreatment of the material to be coated of surfaces of non-metallic or semiconducting in organic material by chemical pretreatment
  • C23C18/1886—Multistep pretreatment
  • C23C18/1893—Multistep pretreatment with use of organic or inorganic compounds other than metals, first
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
  • C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
  • C23C18/18—Pretreatment of the material to be coated
  • C23C18/20—Pretreatment of the material to be coated of organic surfaces, e.g. resins
  • C23C18/28—Sensitising or activating
  • C23C18/30—Activating or accelerating or sensitising with palladium or other noble metal
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
  • C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
  • C23C18/31—Coating with metals
• • 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
  • H01L21/70—Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
  • H01L21/71—Manufacture of specific parts of devices defined in group H01L21/70
  • H01L21/768—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics
  • H01L21/76838—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the conductors
  • H01L21/76841—Barrier, adhesion or liner layers
  • H01L21/76843—Barrier, adhesion or liner layers formed in openings in a dielectric
  • H01L21/76849—Barrier, adhesion or liner layers formed in openings in a dielectric the layer being positioned on top of the main fill metal
• • 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
  • H01L21/70—Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
  • H01L21/71—Manufacture of specific parts of devices defined in group H01L21/70
  • H01L21/768—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics
  • H01L21/76838—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the conductors
  • H01L21/76841—Barrier, adhesion or liner layers
  • H01L21/76871—Layers specifically deposited to enhance or enable the nucleation of further layers, i.e. seed layers
  • H01L21/76874—Layers specifically deposited to enhance or enable the nucleation of further layers, i.e. seed layers for electroless plating
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
  • C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
  • C23C18/31—Coating with metals
  • C23C18/32—Coating with nickel, cobalt or mixtures thereof with phosphorus or boron
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T29/00—Metal working
  • Y10T29/49—Method of mechanical manufacture
  • Y10T29/49002—Electrical device making
  • Y10T29/49117—Conductor or circuit manufacturing
  • Y10T29/49124—On flat or curved insulated base, e.g., printed circuit, etc.
  • Y10T29/49155—Manufacturing circuit on or in base

Definitions

• the present invention relates to a process for the selective coating of certain areas of a composite surface with a conductive film, to a process, a process for the selective coating of a composite surface, the manufacture of interconnections in microelectronics using this process, and integrated circuits.
• microelectronics interconnection manufacturing as well as methods and methods of manufacturing integrated circuits, and more particularly the formation of metal interconnection networks, as well as methods and methods of manufacturing microsystems and connectors.
• An interconnection system consists of several levels. Each level is formed by metal lines and these lines are connected together by contacts called "interconnection holes" or "vias".
• the response time of an interconnection circuit is characterized by a constant RC, which roughly corresponds to the product of the resistance R of the metal levels and their capacitive coupling represented by the constant C, mainly determined by the nature of the dielectric separating the lines. In terms of metallization, the reduction in the response time of the interconnections therefore involves a reduction in the resistance of the lines.
• metallization takes place in three main stages: Stage 1: deposition of a thin barrier layer to the diffusion of copper, by physical vapor deposition ("Physical Napour Deposition: PND) or chemical vapor deposition ("Chemical Vapor Deposition: CVD); Step 2: depositing a thin copper bonding layer also serving as a germination layer for the next deposit; Step 3: electrolytic deposition of copper, during which the substrate acts as a cathode on which the metal is deposited from a solution of its salt. Once the copper deposit has been made, the excess copper is removed by CMP.
• the surface obtained then takes the form of a composite surface comprising alternating strips of copper and dielectric, each of the copper strips being bordered by a very thin semiconductor strip, a vestige of the barrier layer installed in the trenches. before filling with copper, and sliced during polishing.
• These copper strips and the dielectric being formed they are then traditionally encapsulated by a layer, uniform and which covers the entire composite surface, barrier to the diffusion of copper, of SiC or SiC ⁇ type.
• these deposits are insulating, but have a relatively high dielectric constant, which increases the capacitive couplings between copper lines.
• this encapsulation barrier is very adherent with copper, the mobility of copper at the copper-encapsulation barrier interface is greatly reduced and, consequently, the electric current supported by the copper line, without degradation, more important and resistance to electromigration increased.
• the encapsulation barrier must be self-aligned with the underlying copper in order to avoid leakage currents between neighboring copper lines.
• the metallic deposits which may have barrier properties are deposits based on refractory metals such as tungsten, cobalt, nickel or their alloys and mixtures, possibly with certain additive elements such as phosphorus or boron.
• refractory metals such as tungsten, cobalt, nickel or their alloys and mixtures, possibly with certain additive elements such as phosphorus or boron.
• CoWP, CoWB, NiMoP which all have in common to be obtained from electroless solutions comprising in particular salts of cobalt, tungsten, nickel, molybdenum ..., respectively, necessary for the barrier material, as well as a reducing agent (for example dimethyl amino borane or DMAB).
• DMAB dimethyl amino borane
• the copper in the metal lines can provide this catalytic action: the deposition would then take place exclusively on the surface of the copper lines.
• copper is not sufficiently catalytic to allow good growth of the deposit under these conditions.
• palladium activation comprising a step of forming palladium aggregates on the copper lines, followed by a step of locally catalyzed growth of the metallic barrier layer.
• this stage of CMP does not necessarily allow a planarization updating the copper lines well compared to the dielectric lines, a certain number of residues of CMP remain adsorbed on the copper tracks, and cover them with a layer which prevent their reactivity from being expressed, and in particular their redox reactivity.
• the reduction of these ions can, in principle, take place in the entire electroless bath, but it remains catalyzed above all above the copper lines. In fact, this leads to having only one step of cleaning the copper tracks by way of activation (generally by an acid treatment), followed by a step of contact with an electroless bath containing sufficient additives. to enhance the catalytic effect of copper.
• the disadvantage of these alternatives is the intrinsic instability of electroless solutions, and in particular those which must also contain reinforcers of the catalytic effect of copper.
• the inventors have therefore set themselves the goal of providing a process making it possible to meet all of these needs, satisfying the aforementioned specifications, and making it possible to further solve the many aforementioned problems of the prior art, in particular for the manufacture of metallic interconnections, integrated circuits or other microsystems.
• the surfaces concerned by the present invention have the particularity of being composite surfaces, that is to say made up of a tiling of zones differing at least in the work of leaving the material from which they are made.
• the output work of a material is expressed in electronvolts and corresponds to the energy to be supplied, in vacuum, to a surface to extract an electron from it. More particularly and as will be described below, the present invention applies to composite surfaces of which at least one subset of zones is electrically conductive.
• the present invention therefore has as its first object a process for coating a composite material consisting of metallic areas which are electrically conductive or semi-conductive, in particular copper, and areas which are not electrically conductive, said process comprising at least at least one step of electroless growth of a metal layer directly above said electrically conductive or semi-conductive metal areas, characterized in that, the non-electrically conductive areas of the composite material are not formed starting from organic polymers and that prior to said electroless growth step, said method further comprises at least a first step of forming a germination layer by covalent or dative grafting of an organic or organometallic film on and only on said areas conductive metal or semiconductor of electricity, by bringing said composite material into contact with bifunctional, organic or organometallic precursors, of formula (I) below: A- (X) n -B (I) in which: - A is a group comprising at least one reactive chemical function allowing the covalent and selective fixation of said organic precursor on the surface of said electrically conductive areas, -
• the film thus formed has a thickness such that the free face of this film conforms in accordance with the local topology of said composite surface on which it is arranged.
• the thickness of this film is between 1 and 100 nm, more preferably between 1 and 10 nm, and even more preferably between 1 and 5 nm.
• the layer serving for the selective growth of the metallic layer therefore comprises an organic or organometallic film.
• the film is organometallic
• it can be obtained either directly thanks to precursors of formula (I) themselves organometallic, that is to say in which B is a group comprising at least one ligand function complexing metal ions, or via organic precursors leading to an organic film then treated with a solution of metal precursors which are inserted on or in said film, and making it possible to “etch” the grafted organic film.
• This organometallic film therefore comprises an organic part and a metallic material intermingled, with or without chemical interactions or bonds between them, depending on the nature of the chemical materials used.
• the method further comprises a second etching step during which the organic or organometallic film formed on the conductive or semi-conductive metallic areas of the is brought into contact.
• electricity with an etching solution comprising either at least one precursor of a metallic material - or at least one precursor of a catalyst for its deposition, said second step being carried out at the same time as or after the first step of forming the organic film or organometallic.
• the method further comprises, before carrying out the step of electroless growth of the metal layer, a third step consisting in reducing said organometallic compound of formula (I) and / or said precursor of the metallic material or the precursor of a catalyst for its deposition in a metallic material, respectively in a catalyst for its deposition.
• the metallic material is formed in accordance with the topology of the conductive or semi-conductive areas of said composite surface to be coated and on or within said organic film to form with the latter a layer consisting either of a film or of a field of aggregates, respectively, serving either for germination or for catalysis, respectively, of the growth of a metallic layer from an electroless solution.
• the germination or catalysis layer will be called “germination layer”, without further details concerning its effective role in the construction of the upper metallic layer.
• Table I summarizes the various embodiments of the manufacture of the germination layer in accordance with the process according to the invention, depending on the nature of the grafted layer: TABLE I
• the inventors have in fact first of all found that the use of an organic film makes it possible to significantly increase the selectivity of the deposition of the germination layer and therefore of the upper metal layer, in particular because the spontaneous surface chemistry and / or the chemical reactions initiated from the surface to obtain the organic film makes it possible to respect the geometric topology of the composite surface when they are accompanied by a reaction of chemical grafting, that is to say when the adduct of the reaction of the surface with the precursors of these organic or organometallic films leads to chemisorbed species on - that is to say forming a dative or covalent bond with - the conductive or semi-conductive areas of the composite surface.
• the inventors have observed that the selectivity obtained with this type of reaction is greater than that obtained according to the techniques known from the prior art, that is to say by chemical redox deposition by the wet method (electroless). , directly. Furthermore, the non-polymeric nature of the non-electrically conductive areas of the composite material used in accordance with the method of the invention makes it possible to orient the selective fixing of the organic film only directly above the conductive or semiconductive areas of the electricity insofar as the compounds of formula (I) as defined above cannot be attached thereto via covalent or dative bonds.
• the Inventors also noted the property of numerous organic materials constituting such films to be able to shelter and / or to support one or more precursor (s) of metallic materials and to allow the transformation of these precursors into said metallic materials. within or on the surface of these organic films, in particular when these films have reactive functions capable of allowing the formation of dative or covalent bonds with precursors of metallic materials or with the metallic materials themselves.
• the process in accordance with the invention thanks to the presence of organic film directly above the conductive or semi-conductive areas of electricity, makes it possible to considerably reduce the concentration of solutions of metal ions , and in particular palladium, used to carry out the etching step.
• this organic film makes it possible in particular to use solutions of metal ions having a concentration of less than 10 ⁇ 4 M, that is to say much less concentrated than the solutions usually used according to the processes of the art prior. They then used these observations in a very clever way, combining the use of these organic films and these precursors of metallic materials to form germination films on surfaces conforming to the topology of the initial composite surface, even on very small scales, thus solving the many aforementioned problems of the prior art.
• the reactive function of the groups A of bifunctional, organic or organometallic precursors, of formula (I) above is chosen from the functions carrying free doublets such as the amino, pyridine, thiol functions , ester, carboxylic acid, hydroxamic acid, thiourea, nitriles, salicylic, amino acid and triazene; the radicals obtained from cleavable functions such as the disulfide, diazonium (-N 2 + ), sulfonium, iodonium, ammonium, alkyl or aryl iodides; carbocations; carbanions (and in particular those obtained via organomagnesium, organo-zinc, organo-cadmian, organo-cuprate and alkyne).
• the functions carrying free doublets such as the amino, pyridine, thiol functions , ester, carboxylic acid, hydroxamic acid, thiourea, nitriles, salicylic, amino acid and tria
• X is a spacer arm covalently linked to the groups A and B, which can contribute to the stability of the molecule.
• X is preferably chosen from cycles or sets of aromatic cycles, conjugated or not, aliphatic chains, saturated or not, branched or not, and the assemblies of these two types of functions, optionally substituted by electron-withdrawing or electron-donating groups to contribute to the stability of the whole molecule.
• spacer arm X of the linear or branched alkane chains (- (CH 2 ) m -, with l ⁇ m ⁇ 25) such as, for example, the methylene groups (-CH 2 -); the phenylene group (-C 6 H 4 -); phenylene groups substituted by electron-withdrawing groups such as nitro, cyano, hydroxyl, etc., or electron-donor groups such as alkyl groups, preferably having from 1 to 4 carbon atoms such as, for example, the methyl group; groups carrying several fused aromatic rings such as naphthylene, anthrylene groups, etc., themselves themselves optionally substituted by one or more electron-donor or electron-attractor groups; as well as structures made up of combinations of these groupings.
• the spacer arms X of formula - (CH 2 ) m in which m is an integer less than or equal to 10 are particularly preferred according to the invention.
• ligand functions defined above for part B of the bifunctional, organic or organometallic precursors, of formula (I) mention may be made in particular of amines, amides, pyridines, nitriles, amino acids, triazenes, bipyridines, terpyridines, quinolines, orthophenanthroline compounds, ethers, carbonyls, carboxyls and carboxylates, esters, hydroxamic acids, salicylic acids, phosphines, phosphine oxides, thiols, thioethers, disulfides, ureas, thioureas, crown ether, aza-crowns, thio-crowns, cryptands, sepulchrates, podands, porphyrins, calixarenes, naphthols
• the precursor of formula (I) is an organometallic precursor.
• the function X can be “fused” in a single and same grouping with the groups A or B: this is the case for example when we consider a pyridine carrying a group graftable on a metal, the latter grouping being example in the para position of pyridine nitrogen.
• the reactive function is this graftable group
• the pyridine ring takes the place of both X and of ligand function, X being the carbon part of the pyridine ring, the ligand function being the nitrogen of the pyridine ring, of which we know that it has complexing functions with respect to metals.
• Pyrimidines also fall into this category, for example.
• aryl diazonium salts there may be mentioned very particularly 4-ethylammonium phenyl diazonium tetrafluoroborate, 4- (2-aminoethyl) benzenediazonium di-tetrafluoroborate, 4-cyanobenzene-diazonium tetrafluoroborate, 4-carboxy tetrafluoroborate -3-hydroxy-benzene diazonium, 3-carboxy-4-nitrobenzene diazonium tetrafluoroborate, 4-carboxy-benzene diazonium tetrafluoroborate and 4-thioethanol phenyl diazonium tetrafluoroborate.
• the compounds of formulas (I-1-) to (1-14) below are examples of grafting adducts obtained for example from aryl diazonium salts, the cleavage of which leads to the formation of carbon covalent bonds /metal :
• the present invention certainly makes it possible to bring a significant improvement to coating processes comprising an activation step with palladium, but also allows immediate transposition to activations outside palladium (as it appears in Table I above, embodiments I, II, NI and VII, the etching may be carried out following grafting, but with other metal precursors than the palladium precursors, and in particular with cobalt or nickel precursors , or any other element then present in the electroless solution), or even without palladium (etching is not carried out, and the electroless solution is used directly on the grafted layer as is the case of embodiment III of the Table I above).
• the molecules of formula (I) described above can be deposited in various ways on the conductive areas of the composite surfaces, depending in particular on the nature of the functional group A: in most cases, it is observed that the aforementioned groups can react spontaneously and preferably on the conductive or semi-conductive areas of the composite surfaces, to lead to the formation of grafted organic layers, excluding the insulating areas, in which case a simple contacting of the composite surface with a solution containing the molecules of formula (I) (for example by soaking, by centrifugation or by nebulization) may be suitable. It is then a chemical grafting of the organic film onto the conductive or semi-conductive areas of the composite surface.
• the activation of the conductive zones of the composite surface comprises two stages: a stage of activation by grafting and a stage of etching by a metal salt (for example a palladium salt).
• a metal salt for example a palladium salt.
• the surface of the composite material is first treated with the solution containing the precursors of formula (I), according to one of the procedures previously described. This step leads to the formation of a film of bifunctional precursors of formula (I) A- (X) n -B as defined above, grafted onto the conductive areas of the composite material, and offering the groups B comprising at least a ligand function to accommodate metallic precursors.
• the surface is then brought into contact with a solution comprising metal ions M (n +) which can be complexed by the ligand functions of the groups B of the compounds of formula (I) fixed on the conductive areas of the composite material, by soaking, centrifuging or nebulization.
• This treatment allows complexation, which converts the organic film into an organometallic film containing the metal ions of the etching bath.
• the complexation is spontaneously followed by a reduction of the M (n +) ions in metal M °, leading to the spontaneous formation of an organometallic film comprising grafted bifunctional precursors of formula (I) and grafted metal atoms and / or aggregates, via the bifunctional precursors of formula (I), on the conductive zones.
• the atoms or aggregates M ° thus formed are generally catalysts for the reduction of other ions, they favor the pursuit of reduction of M ions ( , if although aggregates grafted onto the conductive areas are quickly obtained rather than single atoms, in a process analogous to that which occurs for palladium directly on copper in the absence of grafting.
• the contact time with the solution of ions M (n +) makes it possible to adjust the size of the aggregates obtained.
• grafting precursors whose spacer X is not too long, typically of a length less than about 5 nanometers (which leads to favoring compounds of formula (I) in which X represents - (CH 2 ) m - with m representing an integer less than or equal to 10, so as to avoid the formation of layers self-assembled in which the chains are straight and move the ligand function of group B too far from the surface).
• the inventors have in fact found that an electroless deposition of metal aggregates on a copper surface only leads to metal / metal bonds if the crystal structures of the two metals are commensurable, that is to say if the geometric parameters of the two types of materials are equal. This is generally not the case, and it is very rare to be able to form metal / metal bonds between the aggregates formed spontaneously on the conductive zones, so that one does not in fact benefit from the enthalpies of metal / metal bond .
• a grafting point is sufficient to constitute a point of attachment for an entire aggregate, which will have been formed from an ion M (n + ) initially complexed, so that each time benefits from improved membership due to the grafting reaction. From this observation, we also conclude that it is the grafting rate of the organic film which can play the role of upper limit of the grafting density of the aggregates: this therefore offers an additional degree of freedom to limit the amount of palladium which will be present at the copper / barrier cover interface in the case of self-aligned barriers.
• the organic or organometallic precursors of formula (I) of the present invention are chosen to carry out a grafting with the conductive or semi-conductive areas of the composite surface, that is to say that the reactive chemical functions of the groups A have a strong affinity for these areas. As illustrated in the exemplary embodiments illustrating the present application, it is found that this affinity is such that the grafting can take place even when no prior cleaning of the conductive areas is carried out. Thus, it is observed that the grafting leads to connections between the part A and the conductive area which are stronger than those maintained by the conductive area - before treatment - with numerous impurities.
• the activation treatment by grafting therefore makes it possible to obtain, on the conductive zones, a grafting which displaces and "resets" the surface state of these zones whatever the treatments which they have undergone in the preceding stages.
• activation by grafting we know that activation by grafting leads to the presence of molecules on the conductive areas, but we know what these molecules are, and we also know that these molecules will promote the selective metallization of these areas.
• the method of the present invention makes it possible to activate, in the same way, the fine strips of semiconductor (TiN, TiNSi, TaN, TaN / Ta, WN.
• vestiges of the barrier layer deposited before filling and CMP it makes it possible to control the adhesion of the self-aligned barrier / line interface not only directly below the copper strip, but also vis-à-vis screw the edges.
• the present invention makes it possible to "seal" the barrier cover (in English “barrier capping”). Because of their redox nature, this property cannot be obtained by the methods of the prior art, the very principle of which is to operate only directly above conductive surfaces.
• the activation of the conductive zones of the composite surface comprises three stages: a stage of activation by grafting, a stage of etching with a metal salt (for example a cobalt salt) and a stage of reduction of the salt thus trapped on conductive areas.
• the additional step added compared to embodiment (1) is generally necessary when the redox potential of the couple (M (n +) / M °) is lower than that associated with the conductive areas of the composite surface: the reduction of ions M (n +) complexed in the grafted film does not occur spontaneously, and must be caused by an external reducing agent.
• any reducer defined as a compound R associated with a couple (R (n +) / R) whose redox potential is lower than that of the couple (M (n +) / M °).
• these reducing agents mention may in particular be made of glucose which allows the reduction of cupric ions (Fehling liquor), and DiMethyl Amino Borane (DMAB) which allows the reduction of most of the transition metal ions.
• DMAB DiMethyl Amino Borane
• the use of this embodiment has the advantage of allowing the formation of metal aggregates of a different nature than palladium, and in particular of aggregates of a metal already present in the electroless solution then used (Co, Ni. ..etc).
• this embodiment allows better control of the size of the aggregates formed (the reduction solution used may - for example - not be contain M (n +) ions to feed the growth of aggregates).
• the reduction solution used may - for example - not be contain M (n +) ions to feed the growth of aggregates).
• this embodiment has the disadvantage of requiring an additional step. Aside from this characteristic, the advantages listed for embodiment (1) remain valid; 3) the activation of the conductive areas of the composite surface comprises a single step: the activation step by grafting an organic layer.
• the electroless solution is used directly on the composite surface thus treated, betting on the fact that this solution contains both metal ions and reducers, for example of the DMAB type.
• the complexation, reduction and electroless growth take place in a single step, which makes it possible to restrict the number of steps in an entirely advantageous manner. Thanks to activation by grafting, the advantages mentioned above, and in particular the insensitivity to the steps preceding activation, the high selectivity offered by grafting, and the additional degree of freedom offered by grafting for the growth of the electroless deposit; 4) the activation of the conductive areas of the composite surface comprises two stages: a stage of activation by grafting from an organometallic precursor, and a stage of reduction of the metal sites carried by these precursors.
• This embodiment makes it possible to directly take advantage of the selectivity of the grafting to fix the metallic seeds on the conductive areas, and therefore to avoid the losses of selectivity which may occur during the etching step, for example.
• This embodiment is particularly suitable for the case where the complementary areas of the conductive areas are made of porous materials, as for example in the activation for electroless barriers in the case where the dielectric separating the conductive lines is a dielectric of low permeability of the type porous; 5) the activation of the conductive areas of the composite surface comprises a single step: an activation step by grafting of organometallic precursors constituting direct catalysts for the electroless growth of the metal layer.
• the ligand functions of the groups B are "charged" with ions M (n + ⁇ associated with a redox couple (M (n +) / M °) fast whose potential is greater than that in which the conductive zones can intervene (such as for example a palladium acetate facing a surface of metallic copper), or else charged directly with metallic aggregates at the degree of zero oxidation; 6) the activation of conductive areas of the composite surface comprises two steps: a step of activating by grafting an organometallic precursor and a step of etching with a metal salt (for example a palladium salt).
• a metal salt for example a palladium salt
• the grafting of a "charged" precursor has been carried out with ions which are not spontaneously reduced by the conductive zones, and the substitution of these ions is carried out during the second step which performs etching, with ions which are spontaneously reduced on the conductive zones (for example palladium ions on conductive zones of copper).
• This embodiment is particularly useful when it is desired to produce a metallic composite deposit on a composite surface consisting of a paving of conductive zones. (SI) or semiconductor (S2) having quite similar output works (W) (W (S1) ⁇ W (S2)).
• organometallic grafting precursors charged with metal ions Ml (n +) it is possible to use organometallic grafting precursors charged with metal ions Ml (n +) , and to carry out the grafting so as to obtain a uniform grafted film (which is possible in areas having output works that are too close for the the selectivity is total, especially if the composite surface has been generally heated or irradiated). Then the composite surface is treated with an etching bath comprising ions M2 (n + - > such that they are spontaneously reduced on S2 but not on SI, which is possible since W (S1) ⁇ W (S2). then a metallic deposit of M2 on S2, but not on SI.
• the activation of the conductive zones of the composite surface comprises three stages: an activation stage by grafting of organometallic precursors, a step of etching with a metal salt not spontaneously reduced on the conductive areas, and a step of reducing the etched ions.
• the difficulty of obtaining a self-aligned germination film by the techniques of the prior art has been postponed and resolved on the basis of the ability to produce an adherent, selective organic film, conforming to the conductive or semi-conductive areas.
• the surfaces concerned by the present invention are as numerous as the different possible applications of the present invention. They can be conductive or semiconductive surfaces of three-dimensional objects, or totally or partially semiconductive surfaces. By three-dimensional surface is meant a surface whose topological irregularities are dimensionally not negligible compared to the thickness of the coating that one seeks to obtain.
• the substrate may for example be an inter-level layer for the manufacture of an integrated circuit, and in particular the surface obtained by chemical mechanical polishing (CMP) following a step of thick electrochemical deposition of copper and filling. trenches and / or vias in the realization of copper interconnections according to the Damascene or Dual Damascene process.
• CMP chemical mechanical polishing
• the composition material comprises surfaces which are almost flat, and made up of alternating copper tracks of width L, separated from dielectric tracks.
• the thinnest widths are those of the first level of metal (level Ml).
• the roadmap for implementing microelectronics manufacturing processes establishes that the width L is around 120 nm for the technological generation at 90 nm, 85 nm for the generation at 65 nm, and 50 nm for the 45 nm generation and 40 nm for the 32 nm generation. According to the invention, this width L is therefore preferably between approximately 150 and 30 nm. It therefore appears that the present invention is all the more relevant when we consider the technological development of the decades to come, given the need to be able to obtain good selectivity of electroless metallic deposition to achieve encapsulation ("capping"). , in English) of increasingly narrow and separate copper lines from increasingly narrow dielectric tracks.
• the method of the present invention therefore solves the many aforementioned problems of the prior art implementing methods which, at these scales, lead to coatings passing over the dielectric tracks and producing an undesirable short circuit of the copper.
• the method of the invention also gives access to dimensions of metallic interconnections never reached.
• the precursors of the metallic material used for the germination layer and used in the mordanting solution during the second step of the process in accordance with the present invention are preferably chosen from metal ions among which mention may be made of ions of copper, zinc, gold, tin, titanium, vanadium, chromium, iron, cobalt, lithium, sodium, aluminum, magnesium, potassium, rubidium, cesium, strontium, yttrium, niobium, molybdenum, ruthenium, rhodium, palladium, silver, cadmium, indium, lutetium, hathium, tantalum, tungsten, rhenium, osmium, iridium, platinum, mercury, thallium, lead, bismuth, lanthanides and actinides and their mixtures.
• the metal precursor can advantageously consist of ions of copper, palladium or platinum.
• the concentration of metal ions within the etching solution used to produce this germination layer is preferably less than or equal to 10 "4 M and even more preferably less than or equal to 10 " 5 M.
• the organometallic precursor may not contain metal ions, but directly metal particles or aggregates.
• the method in accordance with the invention then preferably comprises a step of liberating the particles or metallic aggregates from their gangue in addition to the grafting step.
• the attachment of the metal precursor to, or insertion into, the grafted organic film can be carried out using any suitable technique taking into account the chemical nature of the film and the precursor of the metallic material.
• the method according to the invention makes it possible to force the localization of the precursor of the metallic material on the conductive or semiconductive zones of the surface of the composite material, within the organic film. laterally conforms to the topology of said surface.
• the etching solution used during the second step according to the process according to the invention is a solution which makes it possible to transport the precursor of the metallic material up to the ligand functions of the B groups of the compounds of formula (I) thus allowing their complexation on and / or within the grafted organic film. It is therefore a solution which allows solubilization or sufficient dispersion of the metal precursor for the implementation of the present invention.
• this solution should preferably be able to disperse the precursor of the metallic material sufficiently to be able to allow this precursor to be inserted into the organic film.
• the etching solution will therefore be chosen according to many criteria.
• the solvent of the etching solutions is preferably chosen from solvents having a good power to dissolve ions, and therefore a satisfactory dissociating power, such as water; alcohols such as ethanol, methanol or isopropanol; dimethylformamide (DMF); dimethyl sulfoxide (DMSO); or even acetonitrile.
• solvents having a good power to dissolve ions such as water; alcohols such as ethanol, methanol or isopropanol; dimethylformamide (DMF); dimethyl sulfoxide (DMSO); or even acetonitrile.
• the subject of the invention is also the composite material comprising at least one surface consisting of an alternation of electrically conductive or semi-conductive areas and of non-electrically conductive areas capable of being obtained by implementing the process according to the present invention and as described above, characterized in that the electrically non-conductive areas of the composite material are not formed from organic polymers and that the conductive or semiconductive areas of the electricity are covered with a germination layer grafted covalently or datively and consisting of bifunctional, organic or organometallic compounds, of formula (I) below: A- (X) protest- B (I) in which: - A is a group comprising at least one reactive chemical function allowing the covalent and selective fixing of said organic precursor on the surface of said conductive zones of the electricity, - X is a spacer arm covalently linked to A and B, - n is an integer equal to 0 or 1, - B is a group comprising at least one ligand function for metal ions or for metal aggregates , that is to say allowing the complex
• A, X and B are as defined above.
• the implementation of the process according to the invention is particularly advantageous in the field of microelectronics.
• the present invention also relates to a process for manufacturing interconnections in microelectronics, electronic microsystems or integrated circuits, characterized in that said process comprises at least one step of grafting a film of bifunctional precursors of formula (I ) according to the coating method as described above, said interconnections being made of a metallic material.
• the method of fabrication of metallic interconnects is characterized in that it comprises, in this order, the steps consisting in: a) etching in a dielectric substrate interconnection patterns, said patterns forming trenches and / or vias, on and / or through said substrate, b) depositing on said etched dielectric substrate a conductive barrier layer preventing the migration of the metallic material of interconnections in said substrate, said barrier layer having a thickness such that the free face of this layer follows in accordance with the interconnection patterns of said substrate on which it is deposited, c) coating the conductive barrier layer deposited on the substrate etched with a germination film of a metallic material, d) filling the trenches and / or vias by said metallic material from said germination film to form said metallic interconnections made up of said mat metallic riau, e) achieve uniform and homogeneous abrasion of the surface, for example by chemical mechanical polishing, for a time sufficient to clip the protruding parts
• the present invention finally relates to the use of such a method for the manufacture of interconnection elements in microelectronics, electronic microsystems or integrated circuits as well as interconnection elements in microelectronics, electronic microsystems and circuits integrated obtained by implementing such a method.
• the coating method according to the invention can also be applied to the selective metallization of the source and drain of MOS transistors.
• the invention also comprises other provisions which will emerge from the description which follows, which refers to examples of activation of copper lines of integrated circuits after CMP by grafting a cysteamine film , 4-ethyl tetrafluoroborate (tetrafluoroborate-ammonium) diazonium or ethylenediamine, to an example of grafting on metals of different diazonium salts, to an example of realization of self-aligned barriers according to a process comprising an activation step by grafting according to the method of the invention, to an example of regio-selective grafting of palladium aggregate via a grafting step according to the method of the invention, as well as to the appended FIGS.
• FIG. 1 to 18 in which: - the figure 1 represents a perspective view by scanning electron microscopy at a magnification of 50,000 of the surface of a coupon of 5 x 1 cm 2 obtained by cleavage of a silicon wafer engraved and comprising alternating copper and dielectric lines after CMP but before cleaning; - Figure 2 shows a view through the edge of the coupon shown in Figure 1 at a magnification of 100,000: - Figure 3 shows a perspective view at a magnification of 50,000 of the coupon of Figure 1, but after cleaning with a cleaning solution; - Figure 4 shows a sectional view at a magnification of 100,000 of the coupon of Figure 2, but after cleaning with a cleaning solution; - Figure 5 shows a perspective view at a magnification of
• FIG. 6 shows a sectional view at a magnification of 100,000 of the coupon of Figure 4, after activation of the surface by grafting a cysteamine film and etching with a palladium solution
• - Figure 7 shows a view by the section at a magnification of 80,000 of the coupon of Figure 3 after treatment with a solution for depositing a metal layer according to an electroless process
• FIG. 8 represents the infrared reflection spectra (IRRAS) of silicon coupons (intensity of the peak as a function of the wavelength in cm ⁇ 1 ) and illustrates the evolution of the grafting of an anhydride diazo film after 2 , 10, 30 or 60 minutes of soaking in an anhydride diazo grafting solution.
• IIRRAS infrared reflection spectra
• the highest curve corresponds to the soaking time of 2 minutes, then those which follow down and in this order the times of soaking 10, 30 and 60 minutes;
• - Figure 9 represents the IRRAS spectra of two layers of anhydride diazo obtained by soaking, for 30 minutes at room temperature, of two semi-polished copper surfaces in a 2.10 " mol grafting solution / 1 in diazo anhydride in acetonitrile, before and after soaking in an ultrasonic bath in acetonitrile for 1 hour (low curve: before soaking; high curve: after soaking);
• - Figure 10 shows the patterns "combs / coil" of an integrated circuit comprising alternating copper and dielectric lines;
• - Figure 11 shows the leakage current expressed in amperes as a function of the size of the etching, that is to say the distance of the serpentine comb expressed in ⁇ m, on a circuit conforming to that of Figure 13 according to a process conventional not implementing an organic or organometallic film grafting step;
• FIG. 12 represents the leakage current expressed in amperes as a function of the size of the etching, that is to say the distance of the serpentine comb expressed in ⁇ m, on a circuit conforming to that of FIG. 13 according to a method in accordance with the present invention, that is to say comprising a step of grafting a cysteamine film -
• FIG. 13 is a SEM view at a magnification of 50,000 in perspective of a silicon coupon comprising engravings 0.16 ⁇ m copper after treatment according to a conventional process of the prior art not comprising a step of grafting a compound of formula (I): FIG.
• FIG. 14 is a SEM view at a magnification of 50,000 in perspective of a silicon coupon comprising copper engravings at 0.16 ⁇ m after treatment according to the process according to the invention, that is to say say comprising a step of grafting a cysteamine film, said method further comprising a step of cleaning after CMP using a citric acid solution;
• FIG. 14 is a SEM view at a magnification of 50,000 in perspective of a silicon coupon comprising copper engravings at 0.16 ⁇ m after treatment according to the process according to the invention, that is to say say comprising a step of grafting a cysteamine film, said method further comprising a step of cleaning after CMP using a citric acid solution;
• FIG. 14 is a SEM view at a magnification of 50,000 in perspective of a silicon coupon comprising copper engravings at 0.16 ⁇ m after treatment according to the process according to the invention, that is to say say comprising a step of grafting a cysteamine film, said method further compris
• - Figure 16 is a SEM view at a magnification of 50,000 in perspective of a silicon coupon comprising an alternation of copper and dielectric lines and treated according to the process according to the invention, that is to say comprising a step of grafting a cysteamine film with a solution of 56.8 g of aminoethanethiol, 98% HCl (cysteamine) in 100 ml of ethanol;
• - Figure 17 is a SEM view at a magnification of 50,000 in perspective of a silicon coupon comprising an alternation of copper and dielectric lines and treated according to the process according to the invention, that is to say comprising a step of grafting a cysteamine film with a solution of 56.8 g of aminoethanethiol, 98% HCl (cysteamine) in 100 ml of ethanol;
• - Figure 17 is a SEM view at a magnification of 50,000 in perspective of a silicon coupon comprising an alternation of copper and dielectric lines and
• EXAMPLE 1 ACTIVATION OF COPPER LINES AFTER CMP BY GRAFTING A FILM OF AMINOETHANETHIOL (CYSTEAMINE).
• This example makes it possible to demonstrate the selective formation of catalytic aggregates of palladium on copper lines 200 nm wide, via grafting. prior to an organic layer from cysteamine as a compound of formula (I).
• the composite surfaces used are coupons of 5 x 1 cm 2 , obtained by cleavage of integrated circuits (silicon wafers) etched, after deposition of a TiN barrier, formation of a layer of germination of copper by physical phase deposition steam, electrochemical filling of copper by electrodeposition then chemical mechanical polishing until clipping of the dielectric projections, so as to produce surfaces made of alternating tracks of copper and dielectric (SiO 2 ).
• the surface is cleaned successively with a cleaning solution (SN), the surface treatment with the grafting solution (SG), then with the catalysis solution containing palladium ions as metal precursors (SC).
• SN cleaning solution
• SG grafting solution
• SC catalysis solution containing palladium ions as metal precursors
• Figures 5 and 6 show (at the same magnifications) the result obtained after activation by grafting (SG) then etching by the palladium solution (SC).
• SG grafting
• SC palladium solution
• Figure 7 shows a sectional view of a surface as obtained in Figures 5 and 6 after treatment with a solution of metal ions allowing a metallic deposit according to an electroless process. A localized deposit of about 30 nm is observed at the base of the copper lines, which allows their selective encapsulation, without producing a short circuit between these deposits.
• the grafting solution (SG) is composed of 64.6 mg of DZ-NH 3 + in 100 ml of acetonitrile
• the copper / SiO 2 composite surfaces are cleaned according to the same protocol as described above in Example n ° l, then soaked for 15 minutes in the grafting solution, rinsed with an aqueous sodium hydroxide solution at 0.1 mol / 1, then etched with the catalysis solution as in Example 1.
• An observation with SEM reveals (not shown), as in Example 1 above, the very selective formation of palladium aggregates directly above the copper lines.
• EXAMPLE 3 ACTIVATION OF COPPER LINES AFTER CMP BY GRAFTING OF ETHYLENE DIAMINE (EDA) AS A COMPOUND OF FORMULA (I).
• EDA ETHYLENE DIAMINE
• I COMPOUND OF FORMULA
• EXAMPLE 4 GRAFTING ON METALS OF DIFFERENT DIAZONIUM SALTS This example makes it possible to demonstrate the spontaneous grafting of different diazonium salts on copper surfaces.
• the diazonium salts used in this example are the following:
• the samples used are approximately 5 x silicon coupons
• Figure 9 attached shows the IRRAS spectra of two layers of anhydride diazo obtained by soaking for 30 minutes at temperature. ambient, of two semi-polished copper surfaces in a 2.10 "3 mol / 1 grafting solution in diazo anhydride in acetonitrile, one of which was then treated in an ultrasonic bath in acetonitrile for 1 hour (high curve).
• the results obtained are significant of a reduction in the intensity of the peaks characteristic of the diazo, but not of their disappearance. Even after one hour under ultrasound, the diazo film is still perfectly detectable, which illustrates the strength of the chemical grafting on the metal surface of the composite material in accordance with the method according to the invention.
• EXAMPLE 5 REALIZATION OF SELF-ALIGNED BARRIERS USING AN ACTIVATION STAGE BY GRAFTING - ELECTRIC TESTS.
• This example illustrates the performance improvements brought about by grafting according to the process according to the invention in the activation of composite surfaces during the manufacture of self-aligned barriers.
• Self-aligned barriers are produced for this in the form of electroless deposits of metal alloys, from an electroless solution based on a cobalt salt as described in US Pat. No. 5,695,810. This solution allows a metallic deposit, barrier to the diffusion of copper, by electroless growth catalyzed by the presence of palladium aggregates.
• the solutions and the protocols on the one hand for cleaning (citric acid) and on the other hand for palladium activation are those described above in Example 1.
• the substrates used are coupons of 5 ⁇ 1 cm 2 obtained by cleavage of etched silicon wafers comprising - as in the previous examples - a layer of SiO 2 (the dielectric), a layer of TiN, a layer of germination of copper formed by physical vapor deposition and a layer of thick copper obtained by electroplating, then treated with a CMP step until the dielectric lines are discovered.
• the starting surfaces are therefore composite surfaces made up of alternating copper and dielectric lines. For this example, specific patterns have been chosen.
• FIG. 10 are engraving patterns of the "comb / coil” type, which are ideal for testing the electrical performance of the deposits obtained.
• the tracks shown in FIG. 10 are copper tracks, on which one seeks to come to effect a very selective deposition of a metal barrier.
• the so-called “leakage currents” are measured, by measuring the electric current which passes between a comb and the coil, when they are subjected to a potential difference. If the deposit is ultra-selective, there is no short circuit between the combs and the coil, and a leakage current is measured identical to, or close to, that measured at the start between the copper tracks naked.
• the structures are such that the coils have a total length of 12 and 70 mm.
• Each sample coupon carries several structures, in which the spacing between the combs and the coil is different each time. This makes it possible to test, on the same sample, decreasing structure sizes, and to highlight the contributions of the encapsulation technology for the finest structures. The corresponding results are reported in FIGS.
• FIG. 11 shows the leakage currents obtained for the samples treated according to the conventional methods of the prior art and therefore not forming part of the invention, namely a starting copper / SiO 2 composite substrate, and the composite substrate Cu / SiO 2 after cleaning, palladium activation and electroless deposition. It is observed that the leakage currents obtained are higher on small structures (0.2 ⁇ m in particular).
• Figure 12 shows the results obtained in accordance with the method of the invention when a grafting step is first inserted to enhance the palladium activation. The following sequence was then generally used for the activation: cleaning of the support, grafting of the cysteamine according to the protocol described above in Example 1, activation with palladium + electroless deposition. It is observed that the leakage currents obtained are significantly lower than those obtained above with the conventional method of the prior art not comprising a step of grafting a bifunctional precursor of formula (I).
• Figures 13, 14 and 15 are photographs taken by SEM at a magnification of 50,000 which show the morphology of the deposits obtained on engravings at 0.16 ⁇ m respectively with the traditional protocol not forming part of the invention (without grafting ), according to the invention, that is to say comprising a step of grafting cysteamine as a bifunctional precursor of formula (I), according to the protocol defined in Example 1 above, with or without prior cleaning at the grafting stage. It is noted first of all that the selectivity is - obviously - higher with the process according to the invention, that is to say comprising a grafting step (comparison of Figures 13 and 14), and that morphologies identical are obtained with or without cleaning prior to the grafting step (comparison of Figures 14 and 15).
• PALLADIUM VIA A GRAFTING STAGE This example illustrates the control that grafting allows in controlling the densities and sizes of aggregates obtained during palladium activation. Is carried out, on Cu / SiO 2 composite surfaces identical to those used above in Example 1, a sequence comprising: a cleaning step, a cysteamine grafting step and a palladium etching step. The solutions and protocols used are the same as those described above in Example 1. Only the concentration of cysteamine in the grafting solution has been adjusted.
• - SG F with a cysteamine concentration equal to half the concentration of the grafting solution of Example 1, ie 56.8 g of aminoethanethiol, 98% HCl in 100 ml ethanol
• - SG M with a concentration identical to that of Example 1, ie 113.6 g of aminoethanethiol, 98% HCl in 100 ml of ethanol
• - SG H concentration double that of Example 1, or 227.2 g of aminoethanethiol, HCl 98% in 100 ml of ethanol.
• the etching is carried out with a palladium solution identical to that of Example 1.
• Figure 16 shows a SEM photograph at 50 ⁇ magnification of the results obtained with a grafting step using the SG F grafting solution.
• Figure 17 shows the results obtained with the SG M grafting solution, and Figure 18 with the solution of grafting SG H. It is observed that with identical palladium etching protocol and solution, the concentration of grafting precursor in the organic bath makes it possible to adjust the density and the size of the aggregates, the SG H solution effectively delivering a palladium deposit. more important than the SGM solution, which itself gives a denser deposit than the SG F solution. This also reinforces the idea that grafting has a preponderant role in the quality of the selectivity obtained, since this is identical whatever the density of aggregates produced.

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