Classifications

• • 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
• • 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
  • G03F7/16—Coating processes; Apparatus therefor
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D1/00—Processes for applying liquids or other fluent materials
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D1/00—Processes for applying liquids or other fluent materials
  • B05D1/34—Applying different liquids or other fluent materials simultaneously
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D3/00—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D3/00—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
  • B05D3/06—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by exposure to radiation
  • B05D3/061—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by exposure to radiation using U.V.
  • B05D3/065—After-treatment
  • B05D3/067—Curing or cross-linking the coating
• • 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
  • G03F7/004—Photosensitive materials

Definitions

• the present invention relates to the field of controlling the orientation of the nano-domains of a block copolymer, which are generated at the time of nano-structuring said block copolymer. This orientation depends in particular on the surface energy at each interface of the block copolymer.
• the invention relates to a method for controlling the orientation of the nano-domains of a block copolymer whose upper interface is in contact with a compound, or a mixture of compounds, in liquid form. or solid.
• the invention further relates to a method of manufacturing a nano-lithography mask from a block copolymer, said method comprising the steps of the method of controlling the orientation of the blocks of said block copolymer.
• block copolymers it is possible to structure the arrangement of the constituent blocks of the copolymers, by phase segregation between the blocks thus forming nano-domains, at scales of less than 50 nm. Because of this ability to nanostructure, the use of block copolymers in the fields of electronics or optoelectronics is now well known.
• the block copolymers intended to form nano-lithography masks must have nano-domains oriented perpendicular to the surface of the substrate, so that they can then selectively remove one of the blocks of the block copolymer and create a porous film with the OR the residual block (s).
• the patterns thus created in the porous film can be subsequently transferred, by etching, to an underlying substrate.
• the surface energy (denoted ⁇ ⁇ ) of a given material "x" is defined as being the excess energy at the surface of the material compared to that of the material which has been set in mass. When the material is in liquid form, its surface energy is equivalent to its surface tension.
• Each of the blocks i, ... j of a block copolymer has a noted surface energy ⁇ , ... Vj, which is specific to it and which is a function of its chemical constituents, that is to say -describe the chemical nature of the monomers or comonomers that compose it.
• each of the materials constituting a substrate have their own surface energy value.
• the interaction parameter between two blocks i and j of the block copolymer is therefore denoted x.
• the block copolymer is in contact with two interfaces: an interface called “lower” in the following description, in contact with the underlying substrate, and a so-called “upper” interface, in contact with another compound or mixture of compounds.
• the compound or mixture of compounds at the upper interface consists of ambient air or an atmosphere of controlled composition.
• it may more generally be composed of any compound, or mixture of compounds, molecular constitution and surface energy defined, whether solid or liquid that is to say non-volatile at the auto temperature. -organization of the nano-domains.
• the desired structure that is to say the generation of domains perpendicular to the surface of the substrate, whose patterns may be cylindrical, lamellar, helical or spherical, for example, requires control of surface energies. not only at the lower interface, ie at the interface with the underlying substrate, but also at the upper interface.
• block copolymers as nano-structured masks for applications in microelectronics (lithography, memory point, waveguide ..).
• Graphoepitaxy uses a topological constraint to force the block copolymer to organize in a predefined space and commensurable with the periodicity of the block copolymer.
• graphoepitaxy consists of forming primary patterns, called guides, on the surface of the substrate.
• guides of any chemical affinity with respect to blocks of the block copolymer, delimit zones in which a layer of block copolymer is deposited.
• the guides make it possible to control the organization of the blocks of the block copolymer to form secondary patterns of higher resolution, within these zones.
• the guides are formed by photolithography.
• the surface of the substrate between the guides may be further neutralized so that the surfaces in contact with the subsequently deposited block copolymer do not have a preferential affinity with one of the blocks.
• Mansky et al. in Science, vol. 275, pages 1458-1460 (March 7, 1997) have, for example, shown that a random copolymer of Poly (methyl methacrylate-co-styrene) (PMMA-r-PS) functionalized by an end hydroxyl function chain, allows a good grafting of the copolymer on the surface of a silicon substrate having a native oxide layer (Si / SiO2 native) and obtaining a non-preferential surface energy for the blocks of the copolymer to blocks to nano-structure.
• PMMA-r-PS methyl methacrylate-co-styrene
• the key point of this approach lies in obtaining a grafted layer, to act as a barrier vis-à-vis the clean surface energy of the substrate.
• the inter-facial energy of this barrier with a given block copolymer block is equivalent for each block of the block copolymer, and is modulated by the ratio of comonomers present in the grafted random copolymer.
• the grafting of such a random copolymer thus makes it possible to eliminate the preferential affinity of one of the blocks of the block copolymer for the surface of the substrate, and thus to avoid obtaining a preferential orientation of the nano-domains in parallel with the surface of the substrate.
• the grafting reactions can be obtained by any known means (thermal, photochemical, oxidation-reduction, etc.).
• Chemistry-epitaxy uses, for its part, a contrast of chemical affinities between a pre-drawn pattern on the substrate and the different blocks of the block copolymer.
• a pattern with high affinity for only one block of the block copolymer is pre-drawn on the surface of the underlying substrate, to allow the block copolymer blocks to be oriented perpendicularly, while the rest of the block copolymer is
• the surface has no particular affinity for the blocks of the block copolymer.
• a layer is deposited on the surface of the substrate comprising, on the one hand, neutral zones (constituted, for example, of grafted random copolymer), which do not show any particular affinity with the blocks of the block copolymer to be deposited and of on the other hand, affine areas (consisting of example of graft homopolymer of one of the blocks of the block copolymer to be deposited and serving as anchor of this block of the block copolymer).
• the anchoring homopolymer can be made with a width slightly greater than that of the block with which it has a preferential affinity and allows, in this case, a "pseudo-fair" distribution of the blocks of the block copolymer at the same time. surface of the substrate.
• Such a layer is called “pseudo-neutral” because it allows a fair distribution or “pseudo-fair" blocks of the block copolymer on the surface of the substrate, so that the layer does not exhibit, in its entirety, affinity preferential with one of the blocks of the block copolymer. Therefore, such a chemically epitaxial layer on the surface of the substrate is considered to be neutral with respect to the block copolymer.
• FIG. 1 illustrates the case where the surface energy at the upper interface, between a block copolymer referenced BCP and the ambient air in the example, is not controlled, whereas the lower interface between the underlying substrate and the block copolymer has a chemistry-epitaxial pattern, to guide the orientation of the blocks, with areas shown in black in Figure 1, comprising a homopolymer of one of the blocks of the block copolymer to depositing, and areas shown hatched in Figure 1, comprising a random copolymer neutral to blocks of the block copolymer.
• the chemistry-epitaxial surface does not, as a whole, have a preferential affinity with one of the blocks of the block copolymer, that is to say that the Flory-Huggins parameter Xi -SU bstrat and Xj -SU bstrat is equivalent for each block of the block copolymer. It is then considered that the surface of the substrate, thus chemically-epitaxial, is neutral vis-à-vis the block copolymer.
• a layer of one of the blocks i or j of the block copolymer having the highest affinity with air in FIG. the example of Figure 1, it is block No.
• a first solution could be to anneal the block copolymer in the presence of a gaseous mixture to meet the conditions of neutrality with respect to each block of the block copolymer.
• a gaseous mixture to meet the conditions of neutrality with respect to each block of the block copolymer.
• the composition of such a gas mixture seems very complex to find.
• a second solution when the mixture of compounds at the upper interface consists of ambient air, consists in using a block copolymer whose constituent blocks all have an identical surface energy (or very close) to each other. compared to others, to the temperature of self-organization.
• the perpendicular organization of the nano-domains of the block copolymer is obtained on the one hand, thanks to the neutralized block copolymer / substrate interface, and on the other hand, thanks to the fact that the blocks of the BCP block copolymer naturally have a comparable affinity for the component at the same time. upper interface, in this case the air in the example.
• the surface energy of a given material depends on the temperature.
• the temperature of self-organization for example when we want to organize a block copolymer of large mass or large period, then requiring a lot of energy to obtain a correct organization, it is possible that the difference in surface energy of the blocks then becomes too great for the affinity of each of the blocks of the block copolymer for the compound at the upper interface can still be considered equivalent.
• the increase in the self-organization temperature can then cause the appearance of defects related to the non-perpendicularity of the assembly, due to the difference in surface energy between the blocks of the copolymer to blocks at the self-organizing temperature.
• the top coat is deposited by spin coating (or "spin coating" in English terminology) on the nano-structuring block copolymer film.
• the top coat is soluble in an acidic or basic aqueous solution, which allows its application to the upper surface of the block copolymer, which is insoluble in water.
• the top coat is soluble in a aqueous solution of ammonium hydroxide.
• the top coat is a random or alternating copolymer whose composition comprises maleic anhydride. In solution, the ring opening of maleic anhydride allows the top coat to lose ammonia.
• the cycle of the maleic anhydride of the top coat closes, the top coat undergoes a transformation in a less polar state and becomes neutral with respect to the copolymer. blocks, thus allowing a perpendicular orientation of the nano-domains with respect to the two lower and upper interfaces.
• the top coat is then removed by washing in an acidic or basic solution.
• US 2014238954A describes the same principle as that of US2013 280497, but applied to a block copolymer containing a silsesquioxane type block.
• This solution makes it possible to replace the upper interface between the BCP block copolymer to be organized and a compound or mixture of gaseous compounds, solid or liquid, by a block copolymer interface. top coat.
• the block copolymer is deposited on the surface of the previously neutralized substrate by producing a chemical-epitaxial unit.
• the BCP block copolymer is deposited on a thickness "e" of the order of the Lo period of the copolymer.
• the top coat is deposited. Annealing is then practiced in step 4 in order to nanostruct the block copolymer BCP.
• the top coat is removed in step 5, so as to maintain a nano-structured block copolymer film with nano-domains perfectly perpendicular to the surface of the substrate and on all its thickness "e".
• FIGS. 1 and 2 illustrates the advantage of using a top-coat layer (FIG. 2) when a block copolymer, one of whose blocks (block No. 2) has a preferential affinity with the Ambient atmosphere (Figure 1) is guided via chemistry-epitaxy.
• Figure 1 the top-coat layer makes it possible, during step 4 of annealing nano-structuring, to orient the nano-domains of the block copolymer, perpendicular to the surface of the substrate, over the entire thickness.
• e "of the BCP block copolymer film. This "e” film thickness is at least on the order of a period ("U") of the block copolymer to be able to subsequently transfer the patterns in the substrate.
• the block copolymer film is not at all homogeneous in its thickness "e", i.e. The perpendicularity of the nano-domains in the minimum thickness "e” is not reached because of the preferential affinity of block No. 2 for the ambient atmosphere.
• a first difficulty lies in the deposition of the top-coat layer itself.
• the constituent material of the top-coat layer is soluble in a solvent in which the block copolymer itself is not soluble, otherwise the copolymer will be dissolved again. blocks previously deposited on the substrate.
• the top coat layer can be easily removed, for example by rinsing in a suitable solvent, preferably itself compatible with standard electronic equipment.
• the topcoat layer must have an equivalent interfacial tension for each of the different blocks of the block copolymer to be nanostructured at the time of the heat treatment. Given all these difficulties, the chemical synthesis of the top-coat material may prove to be a challenge in itself. Possible problems of thermal stability of the top coat layer, as well as the density of the top-coat material, which should preferably be lower than that of the block copolymer, may also be mentioned.
• top-coat layer appears to be a priori indispensable for orienting the nano-domains of a block copolymer perpendicular to the substrate, especially when the block copolymer in question is guided through techniques such as graphoepitaxy or chemistry-epitaxy because, otherwise, the efforts made to make the pattern on the substrate to guide the block copolymer would be rendered useless.
• a polymer film on this type of substrate will tend to be strongly inhomogeneous in thickness, and even more so when said polymer is left free to evolve after deposition, for example during a thermal heating beyond beyond the glass transition temperature of the polymer.
• the finer the deposited polymer film is that is to say at least once the gyration radius of a molecular chain of the polymer considered, the more it will tend to be unstable or metastable. more when the surface energy of the substrate is different from that of said polymer and the system is left free to evolve.
• the instability of The polymer film deposited on the substrate is generally all the more important that the torque "annealing temperature / annealing time" is high.
• BCP block copolymers in the form of thin films, for example as lithography masks, it is imperative not only to be able to control the affinity of the upper interface. in order to guarantee the perpendicularity of the patterns with respect to the substrate, but also to be able to guarantee that the BCP block copolymer film covers the entire surface of the substrate without de-wetting it, as well as to guarantee the total absence of dewetting between the deposited BCP block copolymer film and its top coat, when such a top-coat top layer is used.
• the invention therefore aims to remedy at least one of the disadvantages of the prior art.
• the invention aims in particular to propose a simple and industrially feasible alternative solution for controlling the orientation of nano-domains. of any block copolymer, such that the nano-domains are oriented perpendicular to the substrate and the upper interface, over a minimum thickness "e" at least equal to half a period U of the block copolymer and this, without using a top-coat type specific layer that is neutral for the BCP block copolymer.
• the invention also aims to stabilize the block copolymer film deposited on a previously neutralized substrate, vis-à-vis the possible dewetting phenomena with the substrate.
• the subject of the invention is a method for controlling the orientation of the nano-domains of a block copolymer, the lower interface of which is in contact with the previously neutralized surface of a substrate.
• said block copolymer being capable of nano-structuring into nano-domains with a given period, over a minimum thickness at least equal to half of said period, said method being characterized in that it consists in depositing said block copolymer on said substrate, so that its total thickness is at least two times greater than said minimum thickness and preferably at least three times greater than said minimum thickness and then depositing on said block copolymer an interface material making it possible to isolate it of the ambient atmosphere.
• the interface material deposited on the upper interface of the block copolymer has a particular affinity with at least one block of the block copolymer, this affinity being less marked than that of the ambient atmosphere. .
• the thickness of the block copolymer, deposited above the minimum thickness makes it possible, in turn, to compensate for the preferential affinity of one of the blocks of the block copolymer with the component of the interface material.
• this consequent extra thickness also makes it possible to stabilize the BCP block copolymer film deposited with respect to the possible dewetting phenomena with the neutralized substrate.
• the extra thickness allows for example a higher annealing temperature / assembly time, or to slow down the dewetting kinetics or to completely remove it.
• the minimum thickness, on which said block copolymer is intended to nanostructure is chosen equal to an integer or half-integer multiple of the period (U), said multiple being less than or equal to 15 and so preferred, less than or equal to 10;
• a step subsequent to the deposition of the block copolymer consists in proceeding to the self-organization of the block copolymer, so as to nano-structure it on at least said minimum thickness;
• the self-organization of the block copolymer can be carried out by any technique or combination of suitable techniques known to those skilled in the art, the preferred technique being heat treatment;
• the upper interface of the block copolymer is in contact with an interface material comprising a compound, or mixture of compounds of defined molecular constitution and surface energy, which can be solid or liquid at the organization temperature said block copolymer, which makes it possible to isolate the block copolymer film from the influence of the ambient atmosphere or of a defined gas mixture;
• said compound, or mixture of compounds has a particular affinity with at least one block of the block copolymer
• said compound of the upper interface material, in contact with the block copolymer is selected so that its surface energy is at least greater than the value " ⁇ , -5" (in mN / m) and at least lower at the value "y s + 5" (in mN / m), where ⁇ , represents the value of the lowest surface energy among all the values of each block of the block copolymer and where ⁇ 8 represents the value the largest surface energy of all the values of each block of the block copolymer;
• said compound of the upper interface material, in contact with the block copolymer is chosen so that its surface energy is between the values ⁇ , and ⁇ 8 ;
• said compound of the upper interface material is selected so as not to be neutral with respect to each block of the block copolymer
• said compound of the upper interface material is selected as being neutral to each block of the block copolymer;
• the substrate comprises or not patterns, said patterns being pre-drawn by a step or a sequence of lithography steps of any kind prior to the step of depositing the block copolymer film, said patterns being intended to guide the organization of said block copolymer by a technique known as chemistry-epitaxy or graphoepitaxy, or a combination of these two techniques, to obtain a neutralized surface.
• the invention further relates to a method for manufacturing a nano-lithography mask from a block copolymer whose lower interface is in contact with a previously neutralized surface of a substrate under said method comprising the steps of the method for controlling the orientation of the nano-domains of a block copolymer as described above, and being characterized in that after the nano-structuring of the block copolymer, the interface material and an excess thickness of said block copolymer are removed, in order to leave a nanostructured block copolymer film perpendicular to said substrate on said minimum thickness (e) and then at least one of the blocks of said copolymer film is removed to form a porous film suitable for use as a nano-lithography mask.
• the removal step (s) of the interface material and the excess thickness is (are) carried out by a treatment of the chemical-mechanical polishing (CMP) type, solvent, ion bombardment, plasma, or by any combination performed sequentially or concomitantly with said treatments;
• CMP chemical-mechanical polishing
• step (s) removal of the interface material and the extra thickness is (are) performed by plasma dry etching;
• the step of removing one or more blocks of said block copolymer film is carried out by dry etching
• the steps of removal of the interface material, the extra thickness and removal of one or more blocks of the block copolymer film, are performed successively in the same etching frame, by plasma etching;
• the block copolymer may undergo, in whole or in part, a crosslinking / curing step prior to the step of removing said excess thickness;
• the crosslinking / hardening step is carried out by exposing the block copolymer to a light radiation of defined wavelength chosen from ultraviolet, ultraviolet-visible or infra-red, and / or electronic radiation, and / or chemical treatment, and / or atomic or ionic bombardment.
• the invention finally relates to a nano-lithography mask obtained according to the method described above.
• FIG. 1 already described, a diagram seen in section of a block copolymer, deposited on a substrate whose surface has been neutralized by the production of a chemistry-epitaxial unit, before and after the annealing step necessary for its self-assembly, when the surface energy at the upper interface is not controlled,
• FIG. 2 already described, a diagram seen in section of a block copolymer, deposited on a substrate whose surface has been neutralized by the production of a chemistry-epitaxial unit, before and after the annealing step necessary for its self-assembly, when the block copolymer is covered with a specific top surface neutralization layer prior to the annealing step,
• FIG. 3 is a schematic sectional view of a block copolymer at different stages of a method according to the invention for controlling the orientation of the nano-domains of a block copolymer, said method enabling the copolymer to be blocks of nano-structuring such that its nano-domains are oriented perpendicular to the surface of the substrate on a minimum thickness "e".
• polymers is meant either a copolymer (of statistical type, gradient, alternating blocks), or a homopolymer.
• copolymer of statistical type, gradient, alternating blocks
• homopolymer as used refers to a molecule that can undergo polymerization.
• polymerization refers to the process of converting a monomer or mixture of monomers into a polymer.
• copolymer is meant a polymer comprising several different monomeric units.
• random copolymer is understood to mean a copolymer in which the distribution of the monomer units along the chain follows a statistical law, for example of the Bernoullien (Markov zero order) or Markovian first or second order type.
• the repeat units are randomly distributed along the chain, the polymers were formed by a Bernouilli process and are called random copolymers.
• random copolymer is often used, even when the statistical process that prevailed during the synthesis of the copolymer is not known.
• gradient copolymer is understood to mean a copolymer in which the distribution of the monomer units varies progressively along the chains.
• alternating copolymer means a copolymer comprising at least two monomer entities which are distributed alternately along the chains.
• block copolymer is meant a polymer comprising one or more uninterrupted sequences of each of the different polymeric species, the polymer blocks being chemically different from one another, or from one another, and being bound together. by a chemical bond (covalent, ionic, hydrogen bonding, or coordination). These polymer blocks are still referred to as polymer blocks. These blocks have a phase segregation parameter (Flory-Huggins interaction parameter) such that, if the degree of polymerization of each block is greater than a critical value, they are not miscible with each other and separate into nanoparticles. areas.
• phase segregation parameter Flory-Huggins interaction parameter
• miscibility refers to the ability of two or more compounds to mix completely to form a homogeneous or "pseudo-homogeneous" phase, that is to say without crystalline symmetry or quasi -crystalline apparent at short or long distance.
• the miscible character can be determined of a mixture when the sum of the glass transition temperature (Tg) of the mixture is strictly lower than the sum of the Tg of the compounds taken alone.
• period of a block copolymer referred to as U, is meant the minimum distance separating two adjacent domains of the same chemical composition, separated by a domain of different chemical composition.
• minimum thickness "e” is understood to mean the thickness of a block copolymer film serving as a nanolithography mask, below which it is no longer possible to transfer the patterns of the block copolymer film. in the underlying substrate. In general, for block copolymers with a high s phase segregation parameter, this minimum thickness "e” is at least equal to half the period U of the block copolymer.
• porous film refers to a block copolymer film in which one or more nano-domains have been removed, leaving holes whose shapes correspond to the shapes of the nano-domains having been removed and which may be spherical, cylindrical. , lamellar or helical.
• neutral or "pseudo-neutral” surface means a surface which, as a whole, does not have a preferential affinity with one of the blocks of a block copolymer. It thus allows a fair or “pseudoequitable” distribution of blocks of the block copolymer on the surface.
• the neutralization of the surface of a substrate makes it possible to obtain such a "neutral” or "pseudo-neutral” surface.
• lower interface of a block copolymer to be nanostructured, the interface in contact with an underlying substrate on which said block copolymer is deposited. It is noted that throughout the rest of the description, this lower interface is neutralized, that is to say that it does not exhibit, in its entirety, preferential affinity with one of the blocks of the block copolymer.
• upper interface or "upper surface” of a block copolymer to be nano-structured, the interface in contact with a compound, or mixture of compounds, molecular constitution and surface energy defined. , whether solid or liquid, that is to say non-volatile at the self-organization temperature of the nano-domains.
• the compound when the compound is liquid, it may be a solvent or solvent mixture in which the block copolymer is insoluble.
• the compound when solid, it may for example be a copolymer whose affinity with at least one block of the block copolymer is less marked than with the ambient air.
• BCP nano-structuring block copolymer film
• n any integer greater than or equal to 2.
• the block copolymer BCP is more particularly defined by the following general formula:
• A, B, C, D, ..., Z are all blocks "i” ... "j" representing either pure chemical entities, that is to say each block is a set of monomers of identical chemical natures, polymerized together, that is to say a set of co-monomers copolymerized together, in form, in whole or in part, of random or random or gradient or alternating block copolymer.
• the volume fraction of each entity a,..., Z can range from 1 to 99%, in monomer units, in each of the blocks i... Of the BCP block copolymer.
• the volume fraction of each of the blocks i ... j can range from 5 to 95% of the BCP block copolymer.
• the volume fraction is defined as the volume of an entity relative to that of a block, or the volume of a block relative to that of the block copolymer.
• the volume fraction of each entity of a block of a copolymer, or of each block of a block copolymer, is measured in the manner described hereinafter.
• the within a copolymer in which at least one of the entities, or one of the blocks if it is a block copolymer, comprises several comonomers it is possible to measure by proton NMR the mole fraction of each monomer throughout the copolymer, then back to the mass fraction using the molar mass of each monomer unit.
• To obtain the mass fractions of each entity of a block, or each block of a copolymer it is then sufficient to add the mass fractions of the comonomers constituting the entity or the block.
• the volume fraction of each entity or block can then be determined from the mass fraction of each entity or block and the density of the polymer forming the entity or block. However, it is not always possible to obtain the density of polymers whose monomers are co-polymerized. In this case, the volume fraction of an entity or a block is determined from its mass fraction and the density of the bulk majority of the entity or block.
• the molecular weight of the BCP block copolymer can range from 1000 to 500000 g. mol "1 .
• the BCP block copolymer can have any type of architecture: linear, star (tri- or multi-arm), grafted, dendritic, comb.
• the principle of the invention consists in using the preferential affinity of one of the blocks of the BCP block copolymer for the material (liquid, solid, polymer, etc.) of the upper interface, rather than the preferential affinity with the ambient atmosphere, in conjugation with a large thickness of said BCP block copolymer, both to effectively screen this preferential affinity of the lower portions of the block copolymer film and to stabilize the block copolymer film with respect to a possible dewetting phenomenon of the substrate , in order to orient the nano-domains of the block copolymer in a desired direction, over a minimum thickness (e), at the time of the nanostructuring step of said copo BCP block polymer.
• the underlying substrate may be a solid of inorganic, organic or metallic nature. In a particular example, it may be silicon. Its surface is previously neutralized.
• the substrate comprises or not patterns, said patterns being pre-drawn by a step or a sequence of lithography steps of any nature prior to the step of depositing the BCP block copolymer film, said patterns being intended to guide the organization of said BCP block copolymer by a technique known as chemistry-epitaxy or graphoepitaxy, or a combination of these two techniques, to obtain the neutralized surface.
• the block copolymer is capable of nano-structuring into nano-domains with a period (U) over a minimum thickness (e) at least equal to half of said period (U).
• the block copolymer is advantageously deposited on said substrate, with a total thickness (E + e), representing the sum of said minimum thickness (e) and an excess thickness (E), which is at least two times greater than said minimum thickness (e).
• E + e total thickness
• E excess thickness
• any thickness of a liquid or solid material having a particular affinity, even a small one, for at least one of the blocks of the BCP block copolymer is deposited on the BCP block copolymer film, in order to isolate said film BCP of the ambient atmosphere or a defined gas mixture.
• This compound at the upper interface may for example be solid, such as a copolymer for example, or a liquid, such as a solvent, in which the BCP block copolymer is insoluble, or an ionic liquid.
• This method has the enormous advantage, compared to the "top coat" method of the prior art, of not using a higher material which is neutral for the blocks of the BCP block copolymer, but which rather makes it possible to greatly reduce the BCP block copolymer affinity / initial atmosphere.
• the total thickness (E + e) is at least three times greater than said minimum thickness (e).
• the minimum thickness "e” represents the thickness on which the block copolymer must be nanostructured in order to then be able to etch patterns in the underlying substrate by virtue of the nano-structured block copolymer and serving of nano-lithography mask.
• this minimum thickness (e) is at least equal to half the period (Lo) of nano-structuring of the block copolymer.
• FIG. 3 illustrates the step 6 of depositing the BCP block copolymer on the previously neutralized surface, by chemistry-epitaxy, of the substrate and of a layer of interface material intended to serve as a "buffer" layer between the previously deposited block copolymer and the atmosphere.
• This interface material is in solid or liquid form.
• the BCP block copolymer is advantageously deposited over a total thickness (E + e).
• the interface material as well as the "E" allowance of the BCP block copolymer then make it possible to screen and protect the minimum thickness "e" of the BCP block copolymer, the influence of the preferential affinity of the atmosphere with one of the blocks of said block copolymer.
• the air in contact with the interface material deposited on the upper surface of the BCP block copolymer does not affect the depth of the copolymer and in particular the minimum thickness "e".
• the method for controlling the orientation of the nano-domains of a block copolymer according to the invention is therefore universal and applies regardless of the chemical system of the block copolymer.
• the total thickness (E + e) of the BCP block copolymer is chosen so that: (E + e)> 2e, and preferably (E + e)> 3e, with "e" at least equal to to half of Lo.
• the invention is not limited to obtaining a minimum thickness "e" of the order of half of the period Lo.
• this minimum thickness may advantageously be chosen so that it is equal to an integer or half-integer multiple of the period (Lo), said multiple being less than or equal to 15 and preferably less than or equal to 10
• the compound at the upper interface, in contact with the BCP block copolymer may be chosen so that its surface energy is at least greater than the value " ⁇ , -5" (in mN / m).
• the compound at the upper interface, in contact with the block copolymer is chosen such that its surface energy is between the values ⁇ , and ⁇ 8 .
• the compound at the upper interface may be chosen so as not to be neutral with respect to each block of the block copolymer.
• the block copolymer may be deposited according to techniques known to those skilled in the art, such as for example the spin coating technique or “spin coating” in English, “Doctor Blade” “knife System” or “Slot die System”. For this, the BCP block copolymer is premixed in a solvent.
• a step subsequent to the deposition of the BCP block copolymer and the deposition of the material of the upper interface is to carry out the self-organization of the BCP block copolymer so that it is nanostructured on at least l minimum thickness "e" (step referenced 7 in the diagram of Figure 3).
• the self-organization of the block copolymer can be carried out by any technique or combination of appropriate techniques known to those skilled in the art. Preferably, it is carried out by subjecting the obtained stack, comprising the substrate, whose surface has been previously neutralized, the BCP block copolymer and the interface material, to a heat treatment. The block copolymer is then nanostructured under the effect of the heat treatment and the nano-domains obtained are oriented perpendicular to the surface of the substrate on at least said minimum thickness "e".
• the BCP block copolymer when the BCP block copolymer is nano-structured and its patterns are oriented perpendicular to the surface of the substrate, at least said minimum thickness " e ", it is first necessary to remove the material of the upper interface and then to remove the extra thickness" E "(step 8 in Figure 3), to obtain a nano-structured BCP block copolymer film.
• This film is intended to serve as a mask in a subsequent process of nano-lithography, to transfer its patterns in the underlying substrate.
• the removal of the upper interface material and the shrinkage of the "E" allowance of the block copolymer can be carried out, concomitantly or sequentially, by a chemical mechanical polishing (CMP) type treatment. , solvent, ion bombardment, plasma, or any combination of sequentially or concomitantly with these treatments.
• CMP chemical mechanical polishing
• the recesses of the upper interface material and the extra thickness "E" of the block copolymer are made by dry etching, such as plasma etching, for example, whose gas chemistry (s) is used. (s) is chosen so as not to present any particular selectivity for a given block of the BCP block copolymer.
• the etching is done at the same speed for all the blocks of the BCP block copolymer.
• the etching of the "O" thickening is thus performed until leaving on the substrate said minimum thickness "e", previously chosen, BCP block copolymer.
• the block copolymer is for example deposited over a total thickness (E + e) of at least greater than 50 nm, and the upper interface material and the "E" excess thickness are removed in order to maintain a uniform thickness.
• thickness "e" minimum less than 45nm, preferably less than 40nm. This case may, for example, be with a block copolymer of period U equal to 20 nm and for which a minimum thickness "e" equal to U or 21o is required for example.
• the block copolymer Prior to the removal of the excess thickness E, the block copolymer may undergo, in whole or in part, a crosslinking / hardening step. In such a case, the removal of the interface material will be done before removing the extra thickness E, in order to crosslink / cure all or part of the block copolymer.
• This crosslinking / hardening step may be carried out by exposing the BCP block copolymer to a light radiation of defined wavelength selected from ultraviolet, ultraviolet-visible or infrared radiation, and / or electron, and / or chemical treatment, and / or atomic or ionic bombardment.
• a light radiation of defined wavelength selected from ultraviolet, ultraviolet-visible or infrared radiation, and / or electron, and / or chemical treatment, and / or atomic or ionic bombardment.
• a nano-structured BCP block copolymer film on a thickness "e" whose nano-domains are oriented perpendicular to the surface of the substrate under -jacent, as shown in the diagram of Figure 3.
• This block copolymer film is then able to serve as a mask, after removal of at least one of its blocks to leave a porous film and thus be able to transfer its patterns in the underlying substrate by a nano-lithography process.
• the removal of the block or blocks of the block copolymer film can be achieved by any known means such as wet etching using a solvent capable of dissolving the block (s) to be removed while preserving the other blocks or dry etching.
• a stimulus on all or part of said block copolymer film.
• a stimulus can for example be achieved by exposure to UV-visible radiation, an electron beam, or a liquid with acid-base properties or oxidation-reduction, for example.
• the stimulus then makes it possible to induce a chemical modification on all or part of the block copolymer BCP, by cleavage of polymer chains, formation of ionic species, etc.
• Such a modification then facilitates the dissolution of one or more blocks of the copolymer. to remove, in a solvent or mixture of solvents, wherein the other blocks of the BCP copolymer are not soluble before or after exposure to the stimulus.
• the block copolymer intended to serve as a mask is a block copolymer of PS-b-PMMA
• a stimulus by exposure of the block copolymer film to UV radiation will allow the polymer chains of the polymer to be cleaved. PMMA while inducing crosslinking of the PS polymer chains.
• the PMMA units of the block copolymer may be removed by dissolution in a solvent or mixture of solvents judiciously chosen by those skilled in the art.
• Another way to remove a block (s) of the block copolymer film is to use dry etching such as plasma etching for example.
• plasma etching is preferred because it can be carried out in the same frame as the step (s) of removal of the interface material and withdrawal of the "E" extra thickness, alone. the chemistry of the gases constituting the plasma must be changed in order to selectively remove the block (s) to be removed and preserve the other blocks.
• Another advantage of this plasma etching lies in the fact that the removal of the upper interface material, the removal of the extra thickness "E", the removal of (the) blocks of the block copolymer film, and then transferring the patterns of the block copolymer film into the underlying substrate can be made in the same etching frame. In this case, only the chemistry of the plasma gases will have to be changed depending on the materials to be removed.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Plasma & Fusion (AREA)
• Exposure Of Semiconductors, Excluding Electron Or Ion Beam Exposure (AREA)
• Photosensitive Polymer And Photoresist Processing (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Application Of Or Painting With Fluid Materials (AREA)
• Materials For Photolithography (AREA)

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• 2017
  • 2017-07-21 FR FR1756928A patent/FR3069339B1/fr not_active Expired - Fee Related
• 2018
  • 2018-07-20 SG SG11202000393VA patent/SG11202000393VA/en unknown
  • 2018-07-20 CN CN201880048320.0A patent/CN110945426A/zh active Pending
  • 2018-07-20 US US16/631,093 patent/US20200150535A1/en not_active Abandoned
  • 2018-07-20 EP EP18752826.0A patent/EP3655820A1/fr not_active Withdrawn
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