Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D133/00—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Coating compositions based on derivatives of such polymers
  • C09D133/04—Homopolymers or copolymers of esters
  • C09D133/14—Homopolymers or copolymers of esters of esters containing halogen, nitrogen, sulfur or oxygen atoms in addition to the carboxy oxygen
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D133/00—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Coating compositions based on derivatives of such polymers
  • C09D133/04—Homopolymers or copolymers of esters
  • C09D133/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, the oxygen atom being present only as part of the carboxyl radical
  • C09D133/062—Copolymers with monomers not covered by C09D133/06
  • C09D133/066—Copolymers with monomers not covered by C09D133/06 containing -OH groups
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D139/00—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a single or double bond to nitrogen or by a heterocyclic ring containing nitrogen; Coating compositions based on derivatives of such polymers
• • 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
  • G03F7/26—Processing photosensitive materials; Apparatus therefor
  • G03F7/40—Treatment after imagewise removal, e.g. baking

Definitions

• the present invention relates to a composition for coating over a photoresist pattern to improve lithographic performance and also relates to a process for using such a coating for making an image on a substrate.
• Ultra-fine patterns are typically created by forming patterns in a photoresist coating using photolithographic techniques.
• a thin coating of a film of a photoresist composition is first applied to a substrate material, such as silicon wafers used for making integrated circuits.
• the coated substrate is then baked to evaporate any solvent in the photoresist composition and to fix the coating onto the substrate.
• the baked coated surface of the substrate is next subjected to an image-wise exposure to radiation. This radiation exposure causes a chemical transformation in the exposed areas of the coated surface.
• Visible light, ultraviolet (UV) light, electron beam and X-ray radiant energy are radiation types commonly used today in microlithographic processes.
• the coated substrate is treated with a developer solution to dissolve and remove either the radiation-exposed or the unexposed areas of the photoresist.
• Miniaturization of integrated circuits requires the printing of narrower and narrower dimensions within the photoresist.
• Various technologies have been developed to shrink the dimensions to be printed by the photoresist, examples of such technologies are, multilevel coatings, antireflective coatings, phase-shift masks, photoresists which are sensitive at shorter and shorter wavelengths, etc.
• the top coating layer or shrink material may be an inorganic layer such as a dielectric material, or it may be organic such as a crosslinkable polymeric material.
• Dielectric shrink materials are described in US 5,863,707, and comprise silicon oxide, silicon nitride, silicon oxynitride, spin on material or chemical vapor deposited material.
• Organic polymeric coatings are described in US 5,858,620, where such coatings undergo a crosslinking reaction in the presence of an acid, thereby adhering to the photoresist surface, but are removed where the top shrink coating has not been crosslinked.
• US 5,858,620 discloses a method of manufacturing a semiconductor device, where the substrate has a patterned photoresist which is coated with a top layer, the photoresist is then exposed to light and heated so that the photogenerated acid in the photoresist diffuses through the top layer and can then crosslink the top layer. The extent to which the acid diffuses through the top coat determines the thickness of the crosslinked layer. The portion of the top layer that is not crosslinked is removed using a solution that can dissolve the polymer.
• Figure 1 illustrates the imaging process using the shrink material, where (I) denotes a photoresist, (II) denotes an antireflective coating, (III) denotes silicon, (IV) denotes a photoresist pattern. (V) denotes a shrink coating, and (Vl) denotes an interface layer.
• the present invention relates to an aqueous coating composition for coating a photoresist pattern, comprising a polymer comprising at least one unit with an alkylamino group, where the unit has a structure (1 ),
• R 1 to R 5 are independently selected from hydrogen and C 1 to C 6 alkyl, and W is C 1 to C 6 alkylene.
• R 5 is C 1 to C 6 alkyl, more preferably both R 4 and R 5 are C 1 to C 6 alkyl.
• the invention also relates to a process for imaging a photoresist layer using the present novel composition.
• the present invention relates to a coating composition of a shrink coating material comprising a water soluble polymer comprising preferably dialkylamino (-N(alkyh) (alkyl 2 ))groups, that is, the pendant nitrogen attached to the polymer is preferably alkylated with (alkyh) and (alkyl 2 ) groups and free of hydrogen.
• a polymer which is water soluble and comprises the alkylamino group is particularly useful for coating over photoresists sensitive in the deep ultraviolet, especially at 248 nm, 193 nm and 157 nm, where the photoresist polymer comprises groups that can react with the alkylamino group.
• the object of the invention is to form a coating over the imaged photoresist pattern which reacts with the photoresist and stabilizes the photoresist pattern and further increases the dimensional thickness of the photoresist such that narrow spaces can be defined. It has been unexpectedly found that the use of this novel coating shrink composition leads to improved pattern definition, higher resolution, low defects, smaller feature sizes, less temperature sensitivity and stable pattern formation of imaged photoresist.
• the present invention relates to a novel aqueous shrink coating composition
• a water soluble polymer containing preferably at least one alkylamino (preferably dialkylamino) group.
• the polymer is dissolved in a water based solvent composition.
• the composition may be free of additives, such as crosslinking agents, photoacid generators, aminoalcohol compounds, amide compounds, amidoacrylate compounds, and acrylate compounds.
• the composition may contain the novel polymer, and optionally a surfactant, dissolved in water.
• the invention also relates to a process for manufacturing a microelectronic device for reducing the critical dimensions of the patterned photoresist substrate, comprising forming a layer of the novel shrink coating composition on top of an imaged photoresist pattern, reacting a portion of the shrink composition near the photoresist interface, and removing the unreacted, soluble portion of the shrink material with a removal solution.
• Figure 1 illustrates the process for using the shrink material to reduce the spaces between the photoresist patterns, where the photoresist (I) is coated over an antireflective coating (II), imaged to form a photoresist pattern (IV) and then coated with the shrink material composition (V).
• the substrate is heated to form an interface layer (Vl).
• the unreacted shrink layer is removed, thus forming a photoresist/interface layer pattern with a narrower space than with the photoresist alone.
• the novel aqueous shrink coating composition for coating a photoresist pattern comprises a water soluble polymer or essentially a water soluble polymer comprising at least one alkylamino group, where the monomeric unit comprising the dialkylamino group has a structure (1),
• R 1 to R 5 are independently selected from hydrogen and Ci to C 6 alkyl, and W is Ci to C 6 alkylene.
• R 5 is Ci to C 6 alkyl, more preferably R 4 and R 5 are Ci to C 6 alkyl.
• W may be a branched or linear Ci to C 6 alkylene. In one embodiment W may be selected from ethylene, propylene and butylene. In another embodiment R 4 and R 5 may be independently selected from methyl, ethyl, propyl and butyl.
• Ri and R 2 are hydrogen, R 3 is hydrogen or methyl, W is ethyl or propyl, and R 4 and R 5 may be selected from methyl, ethyl, propyl and butyl.
• monomers that may be used to form the monomeric unit of structure (1) are dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate and dimethylaminopropylmethacrylate.
• the polymer may be a homopolymer of the monomeric unit of structure (1 ).
• the polymer may also comprise at least one monomeric unit of structure (1) and at least one other comonomeric unit.
• the comonomeric unit may be a vinyl monomer.
• the polymer in one embodiment, the polymer comprise, a unit of structure (1) and at least one unit of structure (2),
• R 6 to R 8 are independently selected from hydrogen and C 1 to C 6 alkyl
• X, Y, Z and N (nitrogen) combine to form a cyclic structure
• X is selected from Ci to C 6 alkylene, unsaturated Ci to C 6 alkylene, direct bond, and mixtures thereof,
• Y is selected from Ci to C 6 alkylene, unsaturated Ci to C 6 alkylene, direct bond, and mixtures thereof,
• the nitrogen containing ring in structure 2 may comprise one or more saturated bonds, one or more unsaturated bonds, be aromatic or mixtures thereof.
• the unsaturated bond may be a double bond.
• Alkylene is generally referred to as linear or branched within the present invention.
• Examples of the nitrogen containing cyclic group may be without limitation imidazole, N-pyrrolidone, caprolactam, N-morpholine, piperidine, aziridine and triazine.
• monomeric units of structure 2 are monomeric units of structure (2a) and (2b), R7 R a R 7 R n
• R 6 to R 8 are independently selected from hydrogen and Ci to C 6 alkyl, and moiety defined by X, Y, Z are as above in structure 2.
• the nitrogen containing cyclic moiety of structures 2a and 2b may comprise one or more saturated bonds in the cyclic structure, one or more unsaturated bonds in the cyclic structure, be an aromatic ring, or mixtures thereof.
• Examples of the cyclic moiety are imidazole, N-pyrrolidone, caprolactam, N-morpholine, piperidine, aziridine and triazine.
• units of structure (2) are,
• the polymer may comprise at least one monomeric unit of structure (1) as above, optionally a monomeric unit of structure (2) as above, and a third monomeric unit of structure (3),
• R 9 is H or Ci to C 6 alkyl and B is Ci to C 6 alkylene.
• B may be a branched or linear Ci to C- ⁇ alkylene.
• the group B may be ethylene, propylene or butylene, and R 9 may be hydrogen or methyl.
• One example of a monomer which provides the unit of structure (3) is hydroxyethymethacrylate.
• the monomer which provides the monomeric unit of structure (1) may be copolymerized with other vinyl monomers, such as exemplified without limitation by those of structure 2 and 3 and also exemplified by N-vinyl pyrrolidone, acrylic acid, vinyl alcohol, methacrylic acid, N-vinylimidizole, acrylamide, allylamine, vinyl triazines, 2-vinyl-4,6-diamino-1 ,3,5-triazine, diallylamine, vinylamine; N- acryloylmorpholine, piperidinyl methacrylate; and bifunctional monomers such as ethyleneglycoldiacrylate, and ethyleneglycoldimethacrylate.
• the polymer may comprise a mixture of several monomeric units.
• the polymer is free of pendant acrylate groups and/or amide groups.
• the polymer does not use monomers such as (meth)acrylamide in the synthesis of the present inventive polymer.
• the composition contains 1 ) the polymer comprising structure 1 and is free of any amide groups, such as monomeric units derived from (meth)acrylamide, 2) optionally a surfactant, and 3) water.
• the polymer is polymerized from mixtures of at least one of 2-dimethylaminoethyl methacrylate, and at least one of acryloyl morpholine, N-vinyl caprolactam, and N vinyl pyrrolidone.
• the copolymers containing the alkylamino group are exemplified by poly(2-dimethylaminoethyl methacrylate-co-vinyl amine), poly(2-dimethylaminoethyl methacrylate-co-allyl amine), poly(2- dimethylaminoethyl methacrylate-co-diallyl amine), poly(2-dimethylaminoethyl methacrylate-co-acryloyl morpholine), poly(2-dimethylaminoethyl methacrylate- co-N-vinyl caprolactam) and poly(2-dimethylaminoethyl methacrylate-co- piperidinyl methacrylate).
• the polymer comprising the alkylamino group in one embodiment is free of any aromatic moiety or absorbing chromophore, such as groups containing phenyl moiety.
• the polymer or the composition does not absorb the radiation used to image the photoresist which is coated beneath the shrink layer.
• the composition may be free of a photoacid generator such that the composition is not photoimageable.
• the water soluble polymer can be made by any polymerization technique. Bulk or solution polymerization may be used. Typically the vinyl monomers are polymerized using a polymerization initiator, such as azo or peroxide initiators. Examples of peroxide initiators are acetyl peroxide, benzoyl peroxide, lauryl peroxide, cumenehydroperoxide, etc.
• azo initiators examples include azobisisobutyronitrile (AIBN), 2,2'-diamidino-2,2'-azodipropane dihydrochloride, 2,2'-azobis[2-(2-imidazolin-2-yl)propane]dihydrochloride, 2,2'-azobis(2-amidino propane)dihydrochloride, 2,2'-azobis[2-(2-imidazolin-2-yl)propane]dihydrochloride and examples of persulfates are such as ammonium persulfates and potassium persulfates.
• AIBN azobisisobutyronitrile
• 2,2'-diamidino-2,2'-azodipropane dihydrochloride 2,2'-azobis[2-(2-imidazolin-2-yl)propane]dihydrochloride
• 2,2'-azobis(2-amidino propane)dihydrochloride 2,2'-azobis[2-
• the polymerization can be carried out in the presence of a solvent, examples of which are acetonitrile, methanol, ethanol, isopropanol, 2-butanone and water, preferably for some reactions, isopropanol is used.
• the reaction can be carried out for a suitable amount of time and at a suitable temperature.
• the reaction time can range from about 3 hours to about 18 hours.
• the reaction temperature can range from about 40°C to about 80°C.
• the weight average molecular weight of the polymer for the shrink coating material ranges from approximately 3,000 to 100,000, preferably from Mw 5,000 to 100,000, and more preferably from 10,000 to 50,000, but any polymer with the appropriate molecular weight may be used.
• the unit of structure (1) may range from about 20 mole% to about 80 mole%; the unit of structure (2) when used in the polymer may range from about 30 mole% to about 80 mole%; the unit of structure (3) when used in the polymer may range from about 20 mole% to about 60 mole%.
• the copolymer may also comprise the unit of structure (1) in the range from about 20 mole% to about 60 mole% and the unit of structure (2) in the range from about 40 mole% to about 80 mole%.
• the copolymer may also comprise the unit of structure (1) in the range from about 20 mole% to about 60 mole% and the unit of structure (3) in the range from about 40 mole% to about 60 mole%.
• the shrink coating material composition of the present invention comprises the novel water soluble polymer containing the dialkylamino (- N(R 4 )R 5 ) group and water, where the polymer concentration ranges from about 1 weight% to about 20 weight%, preferably 2-10 weight%, and more preferably 2-6 weight% of the composition, depending on the physical parameters of the polymer and the different chemical compositions of the polymer.
• Additives and/or other solvents that are miscible with water may be added to the composition, such as crosslinking agents, water soluble surfactants, alcohols, aminoalcohols, amines, surfactants, thermal acid generators, free acids, photoacid generators, and water soluble polymers other than those containing an alkylamine or amido group.
• water miscible solvents can be used in order to get a uniform coating.
• the water miscible organic solvents used are exemplified by (CrC 8 )alcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol, diols (such as glycols) and triols (such as glycerol); ketones such as acetone, methyl ethyl ketone, 2-heptanone, cyclohexanone; esters such as methyl acetate and ethyl acetate; lactates such as methyl lactate and ethyl lactate, lactones such as gamma-butyrolactone; amides such as N.N-dimethyl acetamide; ethylene glycol monoalkyl ethers such as ethylene glycol monomethyl ether, and ethylene glycol monoethyl ether; ethylene glycol monoalkyl ether acetates such as ethylene glycol
• Solvents such as (Ci-C 8 )alcohols, particularly, isopropanol, methyl alcohol, ethyl alcohol may be added.
• the solvent may be added to the composition at up to about 30 weight% or up to 20 weight% of the total composition.
• Some additives which are added to the shrink material composition comprising the polymer and water can be exemplified by aminoalcohols, such as monoethanolamine, diethanolamine, triethanolamine, 2-(2-aminoethoxy)ethanol, N,N-dimethylethanolamine, N,N-diethanolamine, N-methyldiethanolamine; amines such as monoisopropylamine, diisopropylamine and triisopropylamine, polyalkylenepolyamines, 2-ethylhexylamine, dioctylamine, tripropylamine, tributylamine, triallylamine; and cyclic amines such as piperazine, piperidine, 1 ,4- diazabicyclo[2.2.2]octane, N-methylpiperazine and hydroxyethylpiperazine.
• aminoalcohols such as monoethanolamine, diethanolamine, triethanolamine, 2-(2-aminoethoxy)ethanol, N,N-dimethyl
• Crosslinking agents such as any known crosslinker may be used as an additive, like glycolurils, melamines, urea/formaldehyde polymers, etc.
• the coating composition does not contain a crosslinking agent, especially melamine and urea based crosslinking agents.
• Crosslinking agents are not necessary for the reaction between the polymer of the top coat and the photoresist polymer, since it is believed but not bound by theory, that the present invention involves a base induced reaction of the functionality in the photoresist polymer with the novel polymer of the present invention. Therefore, in one embodiment the shrink material composition is free of crosslinking agents. Surfactants, if necessary, may be added to the shrink composition to enable better film forming properties.
• surfactants are cationic compounds, anionic compounds and nonionic polymers.
• surfactants are Surfynols® sold by Air Products Corp., which are acetylene alcohols. Others can be acetylene glycols, polyethoxylated acetylene alcohols and polyethoxylated acetylene glycols.
• Other water soluble polymers may be added to the composition, such as polyvinyl alcohol, partially acetal capped polyvinyl alcohol, polyallylamine, polyacrylic acid, polymethacrylic acid, poly(vinylpyrrolidone-co- vinyl alcohol), poly(vinylpyrrolidone-co-vinyl melamine), etc.
• These polymers may be added at up to 30 weight% of the solids.
• Free acids such as p- toluenesulphonic acid, perfluorobutanesulphonic acid, perfluorooctanesulphonic acid, ( ⁇ ) camphorsulphonic acid and dodecylbenzenesulphonic acid may be added to the composition.
• thermal acid generators and photoacid generators that are water soluble may be added alone or as mixtures to the novel composition.
• Suitable examples of acid generating photosensitive compounds include, without limitation, ionic photoacid generators (PAG), such as diazonium salts, iodonium salts, sulfonium salts.
• PAG ionic photoacid generators
• the thermal acid generator (TAG) used in the present invention may be any that upon heating generates an acid which can cleave the acid cleavable bond present in the invention, particularly a strong acid such as a sulfonic acid.
• the thermal acid generator is activated at 90°C and more preferably at above 120°C, and even more preferably at above 150°C.
• the photoresist film is heated for a sufficient length of time to react with the coating.
• the free acid, photoacid generator and/or the thermal acid generator may be incorporated in a range from about 0.1 to about 10 weight % by total solids of the composition, preferably from 0.3 to 5 weight % by solids, and more preferably 0.5 to 2.5 weight % by solids.
• the composition and/or the polymer is free of amides.
• the composition is free of amides and additives, that is, the composition contains the present inventive polymer and an aqueous solvent composition.
• the polymer comprising structure (1) is crosslinkable and does not require an additional crosslinking agent.
• the polymer in the composition is free of the carboxylic acid group.
• the composition may also be free of carboxylic acids, amido groups and additives, that is, the composition contains the polymer and a solvent composition comprising water.
• the polymer comprising structure (1) is crosslinkable and does not require a crosslinking agent.
• An imaged pattern of photoresist is formed on a substrate according to processes well-known to those skilled in the art. Photoresists can be any of the types used in the semiconductor industry. There are two types of photoresist compositions, negative-working and positive-working.
• Photoresist resolution is defined as the smallest feature which the photoresist composition can transfer from the photomask to the substrate with a high degree of image edge acuity after exposure and development.
• a photoresist comprises a polymer and a photosensitive compound.
• photoresist systems are novolak/diazonaphthoquinone, polyhydroxystyrene/onium salts, capped polyhydroxystyrene/onium salts, cycloaliphatic polymers/onium salts, cycloaliphatic acrylate polymers/onium salts, and fluoropolymers/onium salts, etc.
• photoresists are well-known for use at wavelengths ranging from 436nm to 13nm. Any type of photoresist that is capable of forming an image may be used.
• a photoresist is coated on a substrate, and the photoresist coating is baked to remove substantially all of the coating solvent. The coating is then exposed with the appropriate wavelength of light, and developed with a suitable developer.
• Suitable device substrates include, without limitation, silicon, silicon substrate coated with a metal surface, copper coated silicon wafer, copper, aluminum, polymeric resins, silicon dioxide, metals, doped silicon dioxide, silicon nitride, silicon carbide, tantalum, polysilicon, ceramics, aluminum/copper mixtures, glass, coated glass; gallium arsenide and other such Group Ill/V compounds.
• the substrate may comprise any number of layers made from the materials described above. Generally one or more layers of an anti reflective coating are coated over the device substrate and the photoresist is coated over the anti reflective coating(s).
• the photoresist layer is formed by coating the photoresist composition over the substrate. Photoresists sensitive to deep ultraviolet radiation, typically 248 nm, 193 nm, and 157 nm are preferred. The photoresist is imaged through a mask and optionally baked. The photoresist is then developed, typically with an aqueous alkaline developer such as tetramethyl ammonium hydroxide solution. The imaging process of a photoresist is known in the art.
• the novel shrink material of the present invention is coated over the substrate with the photoresist pattern and reacted with the surface of the photoresist to form an interface layer which is insoluble in the aqueous removing solution.
• a rinsing solution can remove the shrink material that has not reacted to form the interface layer.
• the interface layer is formed by heating the shrink material coated photoresist pattern at a suitable temperature for a suitable time. The interface layer will increase the width of the photoresist pattern. Thus the space between two adjacent photoresist features will become smaller after the formation of the interface layer, and this narrower space can be used to define smaller features than the photoresist alone.
• Figure 1 illustrates the process of using the shrink composition.
• the novel shrink material of the present invention is coated over the patterned photoresist and reacted with the photoresist.
• the thickness of the reacted shrink interface layer can range from about 10 nm to about 500 nm, preferably 10 nm to 100 nm and more preferably 10 nm to 60 nm.
• the reaction between the shrink coating material and the photoresist to form the interface layer typically occurs during the heating step.
• the opening can be trench or a hole in the photoresist pattern.
• the shrinkage% can range from about 10% to about 60% or about 10% to about 45% or about 10% to about 35%.
• the substrate may be heated between 8O 0 C and 200 0 C, preferably 9O 0 C and 190 0 C, and more preferably between 100 0 C and 180 0 C for 30 seconds to 180 seconds on a hotplate to react the shrink layer and form the interface layer over the photoresist.
• the residual portion of the shrink material that is not reacted with the photoresist to form the interface layer is removed using a removal solution.
• the removal solution may be water or comprises an aqueous solution of a surfactant, which may further comprise an alkali and/or a water-miscible solvent.
• a surfactant such as tetramethyl ammonium hydroxide, tetraethyl ammonium hydroxide, choline or mixtures thereof.
• Water-miscible solvents as also described previously are, for example, lower aliphatic alcohols such as ethanol or isopropanol; multifunctional alcohols such as ethylene glycol, propylene glycol, glycerol, or their monomethyl ethers, in particular propylene glycol monomethyl ether (PGME).
• PGME propylene glycol monomethyl ether
• Water-soluble nonionic surfactants and anionic surfactants were found to provide good lithographic results. Examples of nonionic surfactants are ethylene oxide/propylene oxide polymers, terminated by alkyl, fluoroalkyl, or aromatic groups.
• Anionic surfactants also gave superior lithographic performance, and examples of such surfactants are, salts of longer-chain alkanoic acids, such as laurates, stearates, or heptanoates, salts of alkyl or aralkyl sulfonic acids, such as laurylsulfonic acid, or variously substituted salts of sulfonic acid amides, or the partially or completely fluorinated derivatives of the above classes of compounds.
• Ammonium, tetramethyl ammonium, tetraethyl ammonium, or other alkyl ammonium ions are useful counter ions.
• the actual composition of the removal solution is dependent on factors such as, the shrink material, the desired lithographic performance, compatibility of materials, production specifications, etc.
• the removal solution is applied on the surface of the substrate in a manner known in the art. Puddle development, immersion development, spray development or any mixtures of these techniques may be used to remove chemical compositions from the substrate. The time and temperature of the removal process is varied to give the best lithographic properties. Desirable lithographic properties being, for example, (a) cleanliness of the substrate after removal of the unreacted shrink material, that is, the substrate is free from insoluble deposits, stringers, bridges, etc, (b) vertical wall angles, and (c) smooth surfaces.
• a space reduction of photoresist features obtained with the interface layer over the photoresist of between of from about 10 nm to about 60 nm, preferably about 20 nm to about 50 nm.
• the exact space width reduction requirement is highly dependent on the type of microelectronic devices being manufactured.
• the molecular weight of the polymers was measured on a Gel Permeation Chromatograph.
• the defects were measured using a defect inspection tool, KLA2360 (pixel size 0.25 ⁇ m, manufactured by KLA Tencor Co., San Jose, California, in the exposed and unexposed areas after development.
• KLA2360 pixel size 0.25 ⁇ m, manufactured by KLA Tencor Co., San Jose, California
• N.N-dimethylaminoethylacrylate 25.70 g, 0.1795 mol
• N- vinylpyrrolidone N- vinylpyrrolidone
• initiator azo- bisisobutyronitrile(AIBN)
• 97.50 g of acetonitrile were added to a 500ml round bottom flask equipped with water condenser and nitrogen inlet.
• the initiator concentration was 15 wt% relative to the total weight of the monomers.
• Other solvents such as isopropylalcohol (IPA), 2-butanone and methanol can also be used instead of acetonitrile.
• IPA isopropylalcohol
• 2-butanone 2-butanone
• methanol can also be used instead of acetonitrile.
• a bottom anti-reflective coating material (B.A.R.C), AZ® ArF-1C5D (manufactured by AZ® EM USA Corp, 70 Meister Ave., Somerville, NJ) was spin coated on a silicon substrate and baked at 200 0 C for 60 seconds to prepare an anti reflective coating layer of 0.037 ⁇ m in thickness. Then AZ® AX2050P photoresist solution (a 193 nm photoresist manufactured by AZ EM USA Corp, 70, Meister Ave., Somerville, NJ) was spin-coated on the bottom anti-reflective coated (B.A.R.C) silicon substrate. The photoresist film was baked at 110 0 C for 60 seconds to give a thickness of 0.15 ⁇ m.
• the photoresist film was exposed on a 193 nm scanner (numerical aperture of 0.78 and coherence of 0.9) using a 6% attenuated phase shift mask.
• the wafer was post-exposure baked at 110 0 C for 60 seconds and developed using AZ®626 MIF Developer (manufactured by AZ EM USA Corp, 70, Meister Ave., Somerville, NJ), for 60 seconds, to form a contact hole (C/H) pattern having a diameter of 90nm with 180nm pitch (pitch is the distance between the start of the one hole and the start of the second hole).
• the photoresist patterns were then observed on a scanning electron microscope and the contact hole diameter measured.
• the above described shrink material composition or (RELACS material, Resolution Enhancement Lithography Assisted by Chemical Shrink material) was applied onto the previously photoresist patterned substrate and the thickness of the RELACS or shrink film was 100nm.
• the substrate was subjected to heat treatment (i.e. mixing bake) at 150 0 C for 60 seconds on a hotplate.
• the unreacted shrink material was removed using Dl water puddle for 60 seconds and rinsed for 30 seconds.
• Different experiments were run using different mixing bake temperatures varying from 120°C-160°C for 60 seconds in order to promote a crosslinking reaction at the interface between the photoresist and RELACS layer without an additive, since the polymer is self crosslinkable.
• Shrinkage is a measure of critical dimension (CD) difference of the contact hole diameter (C/H) or trench before and after the RELACS (shrink) process.
• CD critical dimension
• C/H contact hole diameter
• RELACS resistive electrospray
• Shrinkage was measured using CD-SEM (scanning electron microscopy).
• the diameter of the hole in the photoresist/RELACS pattern was reduced by up to 24.4nm from its initial hole diameter in the photoresist pattern. It was found that there is a change in the shrinkage (12nm-25nm) when bake temperature is varied from 120°C -160 0 C.
• the lithographic example as shown above was carried out for Polymers 1-6 and the details are summarized in Table 1. Increasing the mixing temperature increased the shrinkage of the hole.
• the final copolymer (Polymer 9) was vacuum dried at 40 0 C and the yield was 75%.
• the copolymer was characterized by NMR, GPC, and lithographic analysis.
• the weight average molecular weight of the polymer was 19,340 (Mw) and polydispersity was 4.0.
• the synthesis was repeated by varying the mole % of the monomers, dimethylaminoethylacrylate (20-60%), acryloylmorpholine (40-80%), for the different polymers is summarized in Table 3 (Polymers 7-11).
• the molecular weight (Mw) of the polymers was in the range of 15,000-33,000 and the polydispersity was in the range of 2.0-5.0.
• the experimental setup, reaction conditions and isolation process after the reaction were the same as in Example 2.
• the final copolymer (Polymer 22a) was vacuum dried at 40 0 C and the yield was 78%.
• the copolymer was characterized by NMR, GPC, and lithographic analysis.
• the weight average molecular weight of the polymer was 64,401 (Mw) and polydispersity was 6.0.
• the mole % of the monomers, dimethylaminoethylacrylate (10-60%), acryloylmorpholine (30-80%), vinylcaprolactam (10%-60%) for the different polymers (Polymers 12-22d) is summarized in Table 3.
• the molecular weight (Mw) of the polymers was in the range of 16,000-65,000 and the polydispersity was in the range of 2.0-6.0.
• Table 3 Polymerization Data and Shrinkage performance of poMAMOR/DMAEA/VCL) without additive on AZ 2050P (90nm 1 :1 Contact Hole photoresist)
• the mole % of the monomers, dimethylaminoethylacrylate (23-60%), acryloylmorpholine (30-54%), vinylcaprolactam (10%-60%) for the different polymers (Polymers 23-28) is summarized in Table 4.
• the weight average molecular weight (Mw) of the polymers was in the range of 20,000-40,000 and the polydispersity was in the range of 2.0-7.0.
• Table 4 Polymerization Data and Shrinkage performance of polv(AMQR/DMAEA/VC ⁇ on AZ 2050P (90nm 1:1 Contact Hole photoresist) at
• the formulation using Polymer 29 was the same as example 4 (1.8g polymer and 58.9g water). Photoresist and RELACS lithographic process conditions were the same as Example 1.
• the composition with Polymer 29 without any additive showed a hole shrinkage of 8.4nm at mixing temperature of 120°C, 12.0nm at mixing temperature of 130 0 C, 15.4nm at mixing temperature of 140 0 C, 18.3nm at mixing temperature of 150 0 C and 19.9nm at mixing temperature of 160 0 C for 90nm 1 :1 contact hole.
• the formulation using Polymer 30 was the same as example 4, (1.8g polymer and 58.9g water). Photoresist and RELACS lithographic process conditions were the same as Example 1. Composition with Polymer 30 without any additive showed a hole shrinkage of 17.5 nm at mixing temperature of 140°C for 90nm 1 :1 contact hole.
• Example 7a Defect inspection of poly(DMAEA-co-NVP/(40/60)), by KLA
• An anti-reflective coating material AZ® ArF-1C5D (manufactured by AZ EM USA Corp, 70 Meister Ave., Somerville, NJ) was spin coated on a silicon substrate and baked at 200 0 C for 60 seconds to prepare an anti-reflective coating of 0.037 ⁇ m in thickness. Then AZ® AX2050P photoresist solution (manufactured by AZEM USA Corporation, 70, Meister Ave., Somerville, NJ) was spin-coated on the bottom antireflective coated (B.A.R.C) silicon substrate. The photoresist film was baked at 110°C for 60 seconds to give a thickness of 0.15 ⁇ m.
• the photoresist film was exposed on a 193 nm scanner (numerical aperture of 0.78 and coherence of 0.9) using a 6% attenuated phase shift mask. After exposure, the wafer was post-exposure baked at 110 0 C for 60 sec. and developed using AZ®626 MIF Developer (manufactured by AZ EM USA Corp, 70 Meister Ave., Somerville, NJ), for 60 seconds, to form a contact hole pattern having a diameter of 90nm with 180nm pitch. The photoresist patterns were then observed on a scanning electron microscope.
• the shrink coating material made as in Table 1 using Polymer 4 was applied over the photoresist patterned substrate and the shrink film had a thickness of 100nm and was subjected to heat treatment (i.e. mixing bake) at 140 0 C for 60 seconds. Subsequently, the shrink material was removed using Dl water puddle for 60 seconds and rinsed for 60 seconds.
• the defect measurement was done using KLA2360 (pixel size 0.25 ⁇ m (manufactured by KLA Tencor Co.)) in the exposed and unexposed areas after development.
• a smudge defect is where the defect is not a particle but an elliptical smudge-like defect on the surface.
• Example 7b poly(AMOR/DMAEA/VCL) on ArF photoresist, AZ AX2050P (90nm C/H with 180nm pitch)
• An anti-reflective coating material AZ® ArF-1C5D (manufactured by AZ EM USA Corp., 70, Meister Ave., Somerville, NJ) was spin coated on a silicon substrate and baked at 200 0 C for 60s to prepare an anti-reflective coating of 0.037 ⁇ m in thickness. Then AZ® AX2050P photoresist solution (manufactured by AZ EM USA Corp, 70, Meister Ave., Somerville, NJ) was spin-coated on the bottom antireflective coated (B.A.R.C) silicon substrate. The photoresist film was baked at 110 0 C for 60 seconds to give a thickness of 0.15 ⁇ m.
• the photoresist film was exposed on a 193 nm scanner (numerical aperture of 0.78 and coherence of 0.9) using a 6% attenuated phase shift mask. After exposure, the wafer was post-exposure baked at 110 0 C for 60 seconds and developed using AZ®626 MIF Developer (manufactured by AZEM USA Corporation, 70 Meister Ave., Somerville, NJ), for 60 seconds, to form a contact hole pattern having a diameter of 90nm with 180nm pitch. The photoresist patterns were then observed on a scanning electron microscope. The shrink coating material made as in Table 3 using Polymer 22b, was applied onto the patterned photoresist and the thickness of the shrink film was 100nm.
• the substrate was subjected to heat treatment (i.e. mixing bake) at 150 0 C for 60 seconds. Subsequently, the unreacted shrink material was removed using Dl water puddle for 60 seconds and rinse for 30 seconds.
• the mixing bake temperature was varied from 160°C-170 0 C for 60 seconds in order to promote a crosslinking reaction at the interface between the photoresist and shrink layer.
• Shrinkage is a measure of critical dimension (CD) difference of the contact hole (C/H) or trench before and after the shrink process.
• CD critical dimension
• the defect data is summarized in Table 5. The data in Table 5 shows that the particle defects observed were in the acceptable range. The data further showed that there were no smudge defects.

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