TW201541192A - Method for forming pattern using anti-reflective coating composition comprising photoacid generator - Google Patents

Abstract

The present invention relates to a method for forming a pattern by negative tone development (NTD) which is prepared by forming an anti-reflective coating composition layer comprising a photoacid generator between the substrate and the photoresist composition layer, and thus exhibits improved line width (CD) in the pattern and prevents pattern collapse owing to thorough activation of de-blocking of the photoresist composition layer during the exposure process.

Description

Method of forming a pattern using an anti-reflective coating composition comprising a photoacid generator

The present invention is directed to a method of forming a pattern by negative tone development (NTD) in a photolithography process.

The photoresist is a photosensitive composition for transferring an image onto a substrate. After the photoresist coating layer is formed on the substrate, it is exposed to actinic radiation by a photomask. The reticle has an area that is opaque and transparent to actinic radiation. When the photoresist coating is exposed to actinic radiation, a photoinduced chemical modification occurs on the photoresist coating. Therefore, the pattern of the photomask can be transferred to the photoresist coating layer. Thereafter, the photoresist coating layer is developed to form a patterned image that can be selectively processed on the substrate.

Typically, the chemically amplified negatively tuned photoresist comprises an acid labile leaving group of resins and a photoacid generator. When the photoresist is exposed to chemiradiation rays, the photoacid generator forms an acid, and thus the acid formed causes the acid labile group to be detached from the resin during the post-exposure baking process. Acid-labile de-base removal, between exposed and non-exposed areas The difference in solubility characteristics of an aqueous alkaline developer or a hydrophobic organic solvent developer. The exposed region of the resist is soluble in the aqueous alkaline developer and is not soluble in the hydrophobic organic solvent developer. In the manufacturing process of the semiconductor device, the positive-adjusting development process uses an aqueous alkaline developer, leaving only the non-exposed regions of the photoresist on the substrate; conversely, the negative-adjusting development process uses a hydrophobic organic solvent-based developer, and Only the exposed areas of the photoresist are left on the substrate.

In general, photoresists are used to fabricate semiconductors in which a semiconductor wafer (eg, germanium or GaAs (gallium arsenide)) is converted into a composite substrate of an electron conduction path (preferably micro or sub-micron geometry) to perform circuit functions. . For this purpose, proper treatment of the photoresist is quite important. Several operations for processing photoresists are mutually dependent, but one of the most important operations for obtaining high resolution photoresist images is the exposure operation.

In such an exposure operation, when the actinic radiation irradiated onto the photoresist coating layer is reflected, the resolution of the image patterned on the photoresist coating layer may be lowered. For example, when actinic radiation is reflected at the interface between the substrate and the photoresist, the intensity of the actinic radiation that is irradiated onto the photoresist coating layer causes spatial variability, and the actinic radiation is scattered to the unwanted photoresist region, thereby This results in a change in pattern line width or lack of uniformity during development. In addition, since the amount of actinic radiation between the inter-area scattering and reflection is different, the line width may become more inconsistent, for example, depending on the topography of the substrate, the resolution may be limited.

In order to solve the above-mentioned problems associated with reflection, a light absorbing layer, that is, an anti-reflective coating layer, is used between the substrate and the surface of the photoresist coating layer (see U.S. Patent No. 5,939,236, No. 5,886,102, 5,851,738, 5,851,730, etc.).

However, in the case of such a conventional anti-reflective coating layer, when the pattern has a small critical dimension (40 nm or less), negative tone development (NTD) in the photolithography process is often blocked by light. The pattern of the agent is crushed. This phenomenon has caused deterioration in product quality and low yield due to considerable difficulty in ensuring process limits.

Accordingly, in order to overcome the above difficulties, it is an object of the present invention to provide a method of forming a pattern by using negative tone development (NTD) of an anti-reflective coating layer.

To this end, the present invention provides a method of forming a pattern by negative tone development, comprising the steps of: (1) forming on the substrate comprising (a) an organic polymer, (b) a photoacid generator, and (c) An antireflective coating composition layer of the crosslinking agent; (2) forming a photoresist composition layer on the antireflection coating composition layer; (3) a photoresist composition layer and an antireflection coating composition layer Simultaneous exposure to activating radiation followed by baking; and (4) developing the exposed photoresist composition layer with an organic solvent developer.

The method for forming a pattern by negative tone development in the present invention is prepared by forming an anti-reflective coating composition layer containing a photoacid generator between a substrate and a photoresist composition layer, thereby exhibiting an improved pattern line width (CD). And preventing the photoresist pattern from being crushed by completely activating the photoresist layer during the exposure process.

Combined with the drawings (the contents are as follows), and through the following The above and other objects and features of the present invention will be more readily apparent:

Fig. 1 is a view showing the anti-reflective coating composition obtained in Example 1 and Comparative Examples 1 and 2, which was subjected to light lithography which was exposed to negatively developed (NTD) and thereafter exposed to various amounts of light, and the photoresist was formed. SEM image of the line/space pattern of the composition layer.

Exemplary embodiments of the invention are detailed below.

Anti-reflective coating composition for negative tone development (NTD)

The antireflective coating composition for use in the method of forming a pattern by negative tone development in the present invention comprises: (a) an organic polymer, (b) a photoacid generator, and (c) a crosslinking agent.

(a) Organic polymer

The organic polymer comprises: (a-1) at least one unit derived from a cyanurate-based compound having two or more groups selected from a carboxyl group and a carboxyl ester; and (a-2) derived from At least one unit of a glycol or a polyol.

For example, the structural unit (a-1) may be at least one derived from a compound represented by the following formula 1:

In Formula 1, at least two of R ¹ OOC(CX ₂ ) _n -, R ² -, R ³ OOC(CX ₂ ) _m - represent different acid or ester groups; R ¹ , R ² , R ³ and X each independently represents a hydrogen or a non-hydrogen substituent, wherein the non-hydrogen substituent is a substituted or unsubstituted C _1-10 alkyl group, a substituted or unsubstituted C _2-10 alkenyl group, substituted or Unsubstituted C _2-10 alkynyl (eg allyl, etc.), substituted or unsubstituted C _1-10 alkanoyl, substituted or unsubstituted C _1-10 alkoxy (eg A Oxyl, propoxy, butoxy, etc.), epoxy group, substituted or unsubstituted C _1-10 alkylthio group, substituted or unsubstituted C _1-10 alkyl sulfinyl group, Substituted or unsubstituted C _1-10 alkylsulfonyl, substituted or unsubstituted carboxy, substituted or unsubstituted -COO-C _1-8 alkyl, substituted or unsubstituted a C _6-12 aryl group (e.g., phenyl, naphthyl, etc.), or a substituted or unsubstituted 5 to 10 membered heteroalicyclic or heteroaryl group (e.g., methyl phthalimide, N - Methyl-1,8-phthalimide, etc.; and n and m are identical or different from each other, and each is an integer greater than zero

For example, the structural unit (a-2) may be derived from a glycol or a polyol.

Specific examples of suitable glycols may include ethylene glycol; 1,3-propanediol; 1,2-propanediol; 2,2-dimethyl-1,3-propanediol; 2,2-diethyl-1 , 3-propanediol; 2-ethyl-3-methyl-1,3-propanediol; 2-methyl-2-propyl-1,3-propanediol; 2-butyl-2-ethyl-1,3 -propylene glycol; 1,4-butanediol; 2-methyl-1,4-butanediol; 1,2-butanediol; 1,3-butanediol; 2,3-butanediol; 3-dimethyl-2,3-butanediol; 1,5-pentanediol; 1,2-pentanediol; 2,4-pentanediol; 2-methyl-2,4-pentanediol ; 1,6-hexanediol; 2,5-hexanediol; 1,2-hexanediol; 1,5-hexanediol; 2-ethyl-1,3-hexanediol; 2,5- Dimethyl-2,5-hexanediol; 1,7-heptanediol; 1,8-octanediol; 1,2-octanediol; 1,9-nonanediol; 1,10-anthracene Alcohol; 1,2-decanediol; 1,12-dodecanediol; 1,2-dodecanediol; 1,2-tetradecanediol; 1,2-hexadecanediol; 1,16-hexadecanediol; 1,2-cyclobutane dimethanol; 1,4-cyclohexanedimethanol; 1,2-cyclohexanedimethanol; 5-norbornene-2,2- Dimethanol; 3-cyclohexene-1,1-dimethanol; dicyclohexyl-4,4'-diol;1,2-cyclopentanediol;1,3-cyclopentanediol; 2-cyclooctanediol 1,4-cyclooctanediol; 1,5-cyclooctanediol; 1,2-cyclohexanediol; 1,3-cyclohexanediol; 1,4-cyclohexanediol; 1,2-cycloheptanediol; 2,2,4,4-tetramethyl-1,3-cyclobutanediol; 1,2-cyclododecanediol; decalin-1,4- Diol; decalin-1,5-diol; 3-chloro-1,2-propanediol; 1,4-dibromobutane-2,3-diol; 2,2,3,3-tetrafluoro -1,4-butanediol; diethylene glycol; triethylene glycol; tetraethylene glycol; pentaethylene glycol; dipropylene glycol; isosorbide; isomannitol; Alkane-5,5-dimethanol; 1,4-two Alkane-2,3-diol; 1,4-diethane-2,5-diol; 1,2-dithiane-4,5-diol; 2-hydroxyethyl disulfide ; 3,6-dithia-1,8-octanediol; 3,3'-thiodipropanol;2,2'-thiodiethanol;1,3-hydroxyacetone; 1,5-di Hydroxy-2,2,4,4-tetrachloro-3-pentanone; glyceraldehyde; benzopinol; 1,1,4,4-tetraphenyl-1,4-butanediol; 3,4- Bis(p-hydroxyphenol)-3,4-hexanediol; 1,2-benzenedimethanol; 1,4-benzenedimethanol; 2,3,5,6-tetramethyl-p-xylene-α,α '-diol;2,4,5,6-tetrachlorobenzene-1,3-dimethanol;2,3,5,6-tetrachlorobenzene-1,4-dimethanol; 2,2-diphenyl -1,3-propanediol; 3-(4-chlorophenoxy)-1,2-propanediol; 2,2'-(p-phenylenedioxy)-diethanol; 5-nitro-m-xylene -α,α'-diol;1,8-bis(hydroxymethyl)naphthalene;2,6-bis(hydroxymethyl)-p-cresol;O,O' -bis(2-hydroxyethyl)benzene 1,2- O -isopropylidenefuranose; 5,6-isopropylidene ascorbic acid; 2,3- O -isopropylidene threitol and analogues thereof.

Specific examples of suitable triols may contain glycerin; 1,1,1-paraxyl(hydroxymethyl)ethane; 2-hydroxymethyl-1,3-propanediol; 2-ethyl-2-(hydroxymethyl) -1,3-propanediol; 2-hydroxymethyl-2-propyl-1,3-propanediol; 2-hydroxymethyl-1,4-butanediol; 2-hydroxyethyl-2-methyl- 1,4-butanediol; 2-hydroxymethyl-2-propyl-1,4-butanediol; 2-ethyl-2-hydroxyethyl-1,4-butanediol; 1,2, 3-butanetriol; 1,2,4-butanetriol; 3-(hydroxymethyl)-3-methyl-1,4-pentanediol; 1,2,5-pentanetriol; 1,3 , 5-pentanetriol; 1,2,3-trihydroxyhexane; 1,2,6-trihydroxyhexane; 2,5-dimethyl-1,2,6-hexanetriol; Methyl)nitromethane; 2-methyl-2-nitro-1,3-propanediol; 2-bromo-2-nitro-1,3-propanediol; 1,2,4-cyclopentanetriol; , 2,3-cyclopentanetriol; 1,3,5-cyclohexanetriol; 1,3,5-cyclohexanetriethanol; 1,3,5-ginole (2-hydroxyethyl) cyanuric acid; , 2- O - isopropylidene Jiai Du furanose (1,2- O -isopropylideneidofuranose); 1,2- O - isopropylidene-glucofuranose; methyl-xylopyranoside; croconic acid and the like Things.

Particular examples of suitable tetrahydric alcohols may include 1,2,3,4-butanetetraol; 2,2-bis(hydroxymethyl)-1,3-propanediol; 1,2,4,5-pentanediol ; tetrahydroxy-1,4-benzoquinone; α-methylmannose pyranoside; 2-deoxygalactose; 3- O -methyl glucose; ribose; xylose and the like.

The content of the organic polymer may be from 70.0 to 95.0% by weight (wt%) based on the total weight of the antireflective coating composition. More specifically, the content of the organic polymer may be from 78 to 90% by weight.

(b) Photoacid generator

The photoacid generator is not particularly limited and may be used singly or in combination of two or more.

For example, an anthracene salt system or a nitrobenzyl group. Sulfonic acid ester, diazomethane, ethylene dioxane, N -hydroxy quinone sulfonate, and halogen A photoacid generator can be used as the photoacid generator.

The phosphonium salt photoacid generator may be a sulfonate ester, and an anthracene salt including an aromatic group. Specific examples of the phosphonium salt photoacid generator may include triphenylsulfonium trifluoromethanesulfonate, trifluoromethanesulfonic acid (p-t-butoxyphenyl)diphenylphosphonium, trifluoromethanesulfonic acid p-T-butyloxyphenyl) hydrazine, triphenylphosphonium p-toluenesulfonate and the like.

Specific examples of the nitrobenzyl photoacid generator may contain 2-nitrobenzyl p-toluenesulfonate, 2,6-dinitrobenzyl p-toluenesulfonate, 2,4-dinitrobenzyl P-toluenesulfonate and its analogs. Specific examples of the sulfonate-based photoacid generator may contain 1,2,3-cis (methanesulfonyloxy)benzene, 1,2,3-cis (trifluoromethanesulfonyloxy)benzene, 1, 2,3-Sent (p-toluenesulfonyloxy)benzene and its analogs. Specific examples of the diazomethane-based photoacid generator may contain bis(phenylsulfonyl)diazomethane, bis(p-toluenesulfonyl)diazomethane, and the like. Specific examples of the ethylenediamine photoacid generator may contain bis-o-(p-toluenesulfonyl)-α-dimethylglyoxime, bis-o-(n-butylsulfonyl)-α- Dimethylglyoxime and its analogs. Specific examples of the N-hydroxy quinone sulfinate photoacid generator may contain N -hydroxysuccinimide methane sulfonate, N -hydroxysuccinimide trifluoromethane sulfonate, and the like. Halogen Specific examples of the photoacid generator may contain 2-(4-methoxyphenyl)-4,6-bis(trichloromethyl)-1,3,5-tri 2-(4-methoxynaphthyl)-4,6-bis(trichloromethyl)-1,3,5-three And its analogues.

The photoacid generator may be present in an amount of from 0.01 to 15% by weight based on the total weight of the solid content of the antireflective coating composition. More specifically, the photoacid generator may be included in an amount ranging from 3 to 10% by weight.

(c) Crosslinker

The crosslinking agent used in the present invention is not particularly limited, and may be any crosslinking material which can initiate a crosslinking reaction by light and/or heat, preferably a compound which thermally initiates a crosslinking reaction.

When the photoacid generator is exposed to active radiation to release an acid, the above crosslinked substance may be cured, crosslinked or hardened.

Preferred crosslinking agents of the present invention may be, for example, a melamine crosslinking agent, an acetylene urea crosslinking agent, or a benzoquinone. A crosslinking agent, a urea crosslinking agent, and the like. One particular embodiment of the melamine crosslinking agent may be a melamine-formaldehyde resin.

The above cross-linking agents are commercially available, for example, melamine-based cross-linking agents are exemplified by American Cyanamid and sold under the trade names Cymel 300, 301 and 303; acetylene urea-based cross-linking agents are exemplified by American Cyanamid and Cymel 1170 , sold under the trade names of 1171 and 1172; examples of urea-based crosslinkers are manufactured by American Cyanamid and sold under the trade names Beetle 60, 65 and 80; Examples of crosslinkers are available from American Cyanamid and sold under the tradenames Cymel 1123 and 1125.

The content of the crosslinking agent may be from 1 to 20% by weight based on the total weight of the antireflective coating composition. More specifically, the content of the crosslinking agent may be from 5 to 15% by weight.

(d) Thermal acid generator

The antireflective coating composition for negatively developing development may further comprise a thermal acid generator.

The thermal acid generator promotes or improves the crosslinking reaction of the antireflective coating composition layer during the curing process.

Further, the thermal acid generator may be an ionic or substantially neutral thermal acid generator.

In a specific embodiment, the thermal acid generator may be an aromatic hydrocarbon sulfonic acid-based thermal acid generator, more specifically, a benzenesulfonic acid-based thermal acid generator.

The content of the thermal acid generator may be from 0.1 to 2.0% by weight based on the total weight of the antireflective coating composition. More specifically, the content of the thermal acid generator may be from 0.5 to 1.0% by weight.

(e) solvent

The antireflective coating composition may contain a solvent.

Specific examples of the solvent may include oxybutyrate esters such as methyl 2-hydroxyisobutyrate, ethyl lactate and the like; glycol ethers such as 2-methoxyethyl ether, ethylene glycol Monomethyl ether, propylene glycol monomethyl ether and the like; ethers having a hydroxyl moiety, such as methoxybutanol, ethoxylate Butanol, methoxypropanol, ethoxypropanol and the like; esters such as acesulfame acetate, acesulfame acetate, propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether acetate Esters and their analogues; dibasic esters; propylene carbonates; and γ-butyrolactones.

Generally, the solid content of the antireflective coating composition may vary from 0.1 to 2.0 wt%. More specifically, the solid content of the antireflective coating composition may vary from 0.7 to 1.0 wt%.

Method for forming a pattern by negative tone development (NTD)

The method for forming a pattern by negative tone development of the present invention comprises the steps of: (1) forming an anti-reflective coating comprising (a) an organic polymer, (b) a photoacid generator, and (c) a crosslinking agent on a substrate. a composition layer; (2) forming a photoresist composition layer on the anti-reflective coating composition layer; (3) simultaneously exposing the photoresist composition layer and the anti-reflective coating composition layer to activating radiation, Next baking; and (4) developing the exposed photoresist composition layer with an organic solvent developer.

Step (1): formation of an anti-reflective coating composition layer

In this step, an anti-reflective coating composition layer is formed on the substrate.

The antireflective coating composition of the present invention has the same content as described above, and the antireflective coating composition can be prepared by mixing an appropriate amount of the following source materials: an organic polymer, a photoacid generator, a crosslinking agent and the like.

The antireflective coating composition can be applied by any conventional method such as spin coating and the like. The anti-reflective coating composition can be applied to the substrate and it has a dry layer thickness of from 2.0 nm to 50.0 nm. Preferably, the dried layer is between 5.0 nm and 30.0 nm.

Preferably, the applied anti-reflective coating composition layer is cured. The curing conditions will vary depending on the composition of the antireflective coating composition. The curing conditions may be, for example, from 80 ° C to 225 ° C for 0.5 to 40 minutes. The curing conditions preferably render the antireflective coating composition layer substantially insoluble in the photoresist solvent and the aqueous alkaline developer.

The anti-reflective coating composition layer may be formed in a single layer or in multiple layers. For example, before the anti-reflective coating composition layer is formed, a second anti-reflective coating composition layer different from the anti-reflective coating composition layer is formed on the substrate, and the anti-reflective coating composition layer is formed on the first The second anti-reflective coating is on the composition layer.

The formation of the anti-reflective coating composition layer can prevent the deterioration of the pattern quality caused by the reflection of the radiation into the radiation when the photoresist composition layer is exposed to the radiation, and the formation of the anti-reflection coating composition layer can be transmitted during the exposure process. The deblocking of the photoresist composition layer is completely activated to particularly improve the pattern line width (CD) and prevent the pattern pattern from being crushed. In addition, the coating can also improve focus depth, exposure latitude, and line width uniformity.

The substrate may contain one or more layers.

The layer included in the substrate may be one or more conductive layers of aluminum, copper, molybdenum, niobium, titanium, tungsten or alloys thereof; nitride or germanide layer; doped amorphous or doped a polysilicon layer; a dielectric layer such as hafnium oxide, tantalum nitride, hafnium oxynitride or a metal oxide layer; a semiconductor layer such as a single crystal germanium; a glass layer; a quartz layer; and a composition or mixture thereof.

In addition, the layer included in the substrate can pass various technologies. The etching is patterned to form, for example, chemical vapor deposition (CVD) such as plasma enhanced CVD, low pressure CVD or epitaxial growth; physical vapor deposition (PVD) such as sputtering or evaporation; electroplating and the like.

The substrate may contain a hard mask layer. The use of a hard mask layer can be desirable, for example, using a very thin photoresist layer where the layer to be etched requires significant etch depth or a particular etchant has poor photoresist selectivity. When a hard mask layer is used, the photoresist pattern to be formed can be transferred to the hard mask layer and used as a mask for etching the underlying layer.

Typical hard mask materials include, for example, tungsten, titanium, titanium nitride, titanium oxide, zirconium oxide, aluminum oxide, aluminum oxynitride, cerium oxide, amorphous carbon, organic polymers, cerium oxynitride, tantalum nitride. Organic mixed materials of bismuth, but not limited to this. The hard mask layer can be formed by, for example, CVD, PVD or spin coating techniques. The hard mask layer may comprise a single layer or a plurality of layers of different materials.

Step (2): formation of a photoresist composition layer

A photoresist composition layer is formed on the anti-reflective coating composition layer.

The photoresist composition may comprise a matrix polymer, a photoacid generator, and a solvent.

The matrix polymer may comprise at least one unit having an acid cleavable protecting group.

The acid cleavable protecting group may be, for example, an acetal or ester group comprising a quaternary acyclic alkyl carbon (eg, a third butyl group) or a carboxy oxygen quaternary lipid covalently attached to an ester of a matrix polymer. Ring carbon (eg methyl Donkey Kong) alkyl).

Units suitable for inclusion in the matrix polymer may be, for example, units derived from (alkyl) acrylates, preferably units derived from acid cleavable (alkyl) acrylates. Specific examples thereof include tributyl acrylate, t-butyl methacrylate, methyl adamantyl acrylate, methyl adamantyl methacrylate, ethyl decyl acrylate, ethyl decyl methacrylate, and the like. Derived unit.

An embodiment suitable for another unit contained in the matrix polymer may be a unit derived from a non-aromatic cyclic olefin (endocyclic double bond), such as optionally substituted norbornene. There are embodiments which are suitable for use in another unit of the matrix polymer which may be units derived from anhydrides such as maleic anhydride, itaconic anhydride and the like.

Additionally, the matrix polymer may include units of heteroatoms such as oxygen and sulfur, for example, the heterocyclic unit may be fused to the backbone of the matrix polymer.

Further, the matrix polymer may be used in a blend of two or more.

The matrix polymer is commercially available or prepared by those of ordinary skill in the art.

The amount of the matrix polymer of the photoresist composition is sufficient to render the exposed photoresist coating layer developable in a suitable solution, for example, from 50 to 95 parts by weight based on the total weight of the solids content of the photoresist composition. percentage.

The weight average molecular weight (Mw) of the matrix polymer may be less than 100,000, such as 5,000 to 100,000, and more specifically, 5,000 to 15,000.

Further, the photoresist composition may further comprise a photoactive material in an amount sufficient to produce a latent image on the coating layer upon exposure to activating radiation, and particularly comprising a photoacid generator. A suitable photoacid generator may be the same as the photoacid generator set forth in the antireflective coating composition.

In addition, the photoresist composition may contain a solvent such as a glycol ether such as 2-methoxyethyl ether, ethylene glycol monomethyl ether and propylene glycol monomethyl ether; propylene glycol monomethyl ether acetate; a lactate such as ethyl lactate And methyl lactate; propionic acid such as methyl propionate, ethyl propionate, ethyl ethoxypropionate and methyl 2-hydroxyisobutyrate; acesulfame acetate; aromatic hydrocarbons such as toluene and xylene; Ketones such as acetone, methyl ethyl ketone, cyclohexanone and 2-heptanone. These solvents may be used singly or in combination of two or more.

The photoresist composition can be applied to the antireflective coating composition layer by spin coating, dip coating, roll coating or other conventional coating techniques. Preferably, a spin coating method can be used. In the case of spin coating, the solids content of the coating solution can be adjusted to provide the desired film thickness, depending on the particular coating equipment utilized, the viscosity of the solution, the speed of the coating tool, and the time required for spin coating.

The thickness of the photoresist composition layer may be, for example, from 50 nanometers (nm) to 300 nm.

Next, the photoresist composition layer can be soft baked to minimize the amount of solvent in the layer to form a non-stick coating layer and adhesion of the modified layer to the substrate. Soft baking can be carried out on a hot plate or in an oven. The soft bake temperature and time will depend on the particular material and thickness of the photoresist. For example, a typical soft bake is carried out at 90 ° C to 150 ° C for about 30 to 90 seconds.

Alternatively, an overcoat layer may be formed on the photoresist composition layer. The purpose of forming the overcoat layer is to make the photoresist pattern uniform, reduce the reflectance of the photoresist exposure process, improve the depth of focus and exposure latitude, and reduce defects. The overcoat layer can be formed using a topcoat composition by spin coating techniques. The solids content of the coating solution can be adjusted to provide the desired film thickness, depending on the particular coating equipment utilized, the viscosity of the solution, the speed of the coating tool, and the time required for spin coating. The outer coating thickness may be, for example, 200 Å to 1,000 Å.

The outer coating can be soft baked to minimize the amount of solvent in the layer. Soft baking can be carried out on a hot plate or in an oven. A typical soft bake is carried out at 80 ° C to 120 ° C for about 30 to 90 seconds.

Step (3): Exposure

Next, the photoresist composition layer is exposed to activating radiation through a photomask to produce a difference in solubility between the exposed and unexposed regions.

The reticle has optically transparent and optically opaque areas.

The exposure wavelength may be, for example, 400 nm or less, 300 nm or less, or 200 nm or less, preferably 248 nm (such as krypton fluoride (KrF) excimer laser light) or 193. Nano (such as argon fluoride (ArF) excimer laser light).

The exposure energy is typically between about 10 and 80 millijoules (mJ) per square centimeter (cm ² ), depending on the composition of the exposure apparatus and the photosensitive composition.

After the exposure process of the photoresist composition layer, post-exposure bake (PEB) is performed.

Post-exposure bake can be carried out on a hot plate or in an oven. The conditions for post-exposure baking may differ depending on the composition and thickness of the photoresist composition layer. For example, a typical post-exposure bake is carried out at 80 ° C to 150 ° C for about 30 to 90 seconds.

Therefore, the latent image system is generated in the photoresist composition layer due to the difference in solubility between the light exposure and the unexposed regions.

Step (4): development

The outer coating and the exposed photoresist composition layer are then developed to remove unexposed regions to form a photoresist pattern.

The developer is typically an organic developer such as a solvent selected from the group consisting of ketones, esters, ethers, guanamines, hydrocarbons and mixtures thereof.

Specific examples of suitable ketones include acetone, 2-hexanone, 5-methyl-2-hexanone, 2-heptanone, 4-heptanone, 1-octanone, 2-octanone, 1-nonanone, 2-nonanone, diisobutyl ketone, cyclohexanone, methylcyclohexanone, phenylacetone, methyl ethyl ketone, and methyl isobutyl ketone. Specific suitable ester examples include methyl acetate, butyl acetate, ethyl acetate, isopropyl acetate, amyl acetate, propylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol Monobutyl ether acetate, diethylene glycol monoethyl ether acetate, ethyl 3-ethoxypropionate, 3-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate, Methyl formate, ethyl formate, butyl formate, propyl formate, ethyl lactate, butyl lactate and propyl lactate. Specific examples of suitable ethers contain two Alkanes, tetrahydrofuran, and glycol ethers (eg, ethylene glycol monomethyl ether, propylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monoethyl ether, diethylene glycol monomethyl ether, triethylene glycol monoethyl ether, and methoxymethyl) Butanol). Specific examples of suitable guanamines include N -methyl-2-pyrrolidone, N,N -dimethylacetamide, and N,N -dimethylformamide. Particular embodiments of suitable hydrocarbons contain aromatic hydrocarbon solvents such as toluene and xylene.

The developer may include a solvent that can be used in the photoresist composition, such as 2-heptanone, butyl acetate (e.g., n-butyl acetate).

The developer may comprise a mixture of the above solvents, or a mixture of one or more of the above solvents with other solvents or water.

For example, the developer may include a mixture of the first organic solvent and the second organic solvent. Specific examples of the first organic solvent are C _4-9 ketones; hydroxyalkyl esters such as methyl 2-hydroxyisobutyrate, ethyl lactate; and linear or branched C _5-6 alkoxyalkyl groups; An ester such as propylene glycol monomethyl ether acetate, and preferably 2-heptanone or 5-methyl-2-hexanone. Specific examples of the second organic solvent are linear or branched C _6-8 alkyl esters such as n-butyl acetate, n-pentyl acetate, n-butyl propionate, n-hexyl acetate, n-butyl butyrate, and Isobutyl butyrate; and a linear or branched C _8-9 ketone such as 4-octanone, 2,5-dimethyl-4-hexanone, 2,6-dimethyl-4-heptanone, And preferably n-butyl acetate, n-butyl propionate or 2,6-dimethyl-4-heptanone. Specific examples of combinations of the first and second organic solvents contain 2-heptanone/n-butyl propionate, cyclohexanone/n-butyl propionate, PGMEA/n-butyl propionate, 5-methyl-2- Hexanone/n-butyl propionate, 2-heptanone/2,6-dimethyl-4-heptanone, 2-heptanone/n-butyl acetate. Among them, 2-heptanone/n-butyl acetate or 2-heptanone/n-butyl propionate is preferred.

The amount of solvent which may be present in the developer may range from 90 to 100 weight percent, preferably greater than 95 weight percent, greater than 98 weight percent, greater than 99 or 100 weight percent.

The developer may also contain optional additives such as surfactants and the like. These optional additives will typically be present at lower concentrations, for example from about 0.01 to 5 weight percent.

The developer can be applied to the photoresist composition layer by known techniques, such as spin coating or puddle coating. The development time is a period of time during which the unexposed areas of the photoresist are effectively removed. For example, it is developed at room temperature for 5 to 30 seconds.

The developed photoresist composition layer can be further cured by additionally baking at 100 ° C to 150 ° C for several minutes.

The developed substrate may have a substrate area through which the photoresist is removed, and the substrate area may be processed in a selective manner. For example, the substrate area through which the photoresist is removed may be chemically etched or plated using methods known in the art. A hydrofluoric acid etching solution and a plasma gas etchant such as an oxygen plasma etchant can be used as an etchant. For example, a plasma gas etchant can be used to remove the anti-reflective coating composition layer and etch the substrate.

Hereinafter, the present invention will be more specifically described by the following examples, but these examples are for illustrative purposes only, and the invention is not limited thereto.

Suitable for the synthesis of 193 nm anti-reflective coating polymers

In the following Preparations and Examples, the reaction apparatus was a 100 ml (ml) three-necked flask equipped with a round bottom flask equipped with a magnetic stirrer. It consists of a temperature adjustment box, a temperature probe, an oil bath and a condenser.

Preparation Example: Synthesis of Polymer A-1

13.0 g (g) of ginseng (2-hydroxyethyl) isocyanurate, 8.6 g of ginseng (2-carboxyethyl) isocyanurate, 0.24 g of p-toluenesulfonic acid monohydrate, 5.16 g of n-butyl The alcohol and 14.6 grams of anisole were placed in the reaction flask without any particular order. The reaction flask was heated to 140 to 160 ° C and then vigorously stirred for 6 hours to carry out the reaction. Anisole and n-butanol were slowly distilled from the reaction flask. The resulting reaction was diluted with 67.8 g of methyl 2-hydroxyisobutyrate and neutralized with triethylamine.

To 19.2 g of the thus obtained polymer solution, 4.09 g of methyl 2-hydroxyisobutyrate and 9.92 g of tetramethoxymethylacetylene urea were added. The mixture was stirred at 50 ° C for 3 hours to carry out a reaction, cooled to room temperature, and neutralized with triethylamine.

The obtained reactant was precipitated by adding 10 times the amount of isopropanol/heptane (volume ratio 60/40 (v/v)) to the reactant. The resulting precipitate was washed with heptane and filtered through a Buchner funnel to obtain a solid, which was then air-dried and dried under vacuum at 40 to 50 ° C to the next day to obtain a polymer.

Gel permeation chromatography (GPC) was carried out using a polymer in THF, and the polymer showed: molecular weight = 8,500; and molecular weight distribution = 2.9.

Preparation: Synthesis of polymer A-2

27.4 g of t-butylglycidyl bis(2-carboxyethyl)isocyanurate, 14.3 g of ginseng (2-hydroxyethyl)isocyanurate, 8.3 g of 1,2-propanediol and 30 g of Anisole was placed in the reaction flask without any particular order. will The reaction flask was heated to 150 ° C and then vigorously stirred for 6 hours to carry out the reaction. The solvent and reaction by-products were slowly distilled off from the reaction flask. The resulting reaction was diluted with tetrahydrofuran to a solid weight of 30% by weight.

The resulting reactant was precipitated by adding 10 times the amount of isopropanol to the reactant. The resulting precipitate was collected and filtered through a Buchner funnel to obtain a solid, which was then air-dried and vacuum dried at 40 to 50 ° C until the next day to obtain a polymer.

Gel permeation chromatography (GPC) was carried out using a polymer in THF, and the polymer showed: molecular weight = 8,700; molecular weight distribution = 1.96; n193 = 1.94; and k193 = 0.24.

Synthesis of anti-reflective coating composition

The following ingredients were used in the preparation of the examples and comparative examples:

(A-1) and (A-2) polymer: the polymer obtained in the preparation example

(B-1) Acid catalyst: p-toluenesulfonic acid (PTSA)

(C-1) Crosslinker: tetramethoxymethyl acetylene urea (TMGU)

(D-1) Solvent: methyl 2-hydroxyisobutyrate (HBM)

Comparative example 1

2.741 g of (A-1) polymer, 0.0260 g of (B-1) acid catalyst, 0.732 g of (C-1) crosslinker, and 346.5 g of (D-1) solvent were mixed and stirred for 1 hour, followed by polytetrafluoro A 0.45 micron filter made of ethylene (PTFE) was filtered.

Comparative example 2

2.741 g of (A-2) polymer, 0.0260 g of (B-1) acid catalyst, 0.732 g of (C-1) crosslinker, and 346.5 g of (D-1) solvent were mixed and stirred for 1 hour, followed by polytetrafluoro A 0.45 micron filter made of ethylene (PTFE) was filtered.

Example 1

2.982 g of (A-2) polymer, 0.0272 g of (B-1) acid catalyst, 0.509 g of (C-1) crosslinker, and 339.7 g of (D-1) solvent were added, and further 0.204 g of trifluoromethanesulfonate was added. Triphenyl hydrazine (TPS-TF). The mixture was stirred for 1 hour and then filtered through a 0.45 micron filter made of polytetrafluoroethylene (PTFE).

Evaluation of 193 nm Negative Tuning Development lithography

Each of the antireflective coating compositions prepared in the examples and the comparative examples was tested for lithographic efficacy by negative tone development (NTD).

A tantalum substrate was prepared, and then an antireflection layer (n193=1.69, k193=0.63) for reflectance control was formed on the substrate by a spin coating technique, and then baked at 205 ° C to cure the antireflection layer. The antireflective coating composition prepared in the examples and the comparative examples was spin-coated to the substrate of the coated antireflection layer to form a layer. During this process, the 193 nm light reflection caused by the substrate during exposure can be minimized by adjusting the rotational speed. The coating layer thus formed was baked at 205 ° C to cure the antireflective coating composition layer. A negatively developed photoresist composition is applied to the cured coating layer for exposure. Exposure The S610C exposure apparatus was used in the light process (immersion lithography, NA 1.3, X-dipole illumination, σ=0.74 to 0.95, Y-polarization, 41 nm/82 p 6% 180° PSM mask). Next, the coating layer was developed via n-butyl acetate to obtain a line/space pattern.

The pattern formed was observed under a scanning electron microscope to measure the line width of the pattern, and the pattern image obtained by exposure to various amounts of light was as shown in Fig. 1. In addition, the measurement results of the line width CD of each sample are summarized in Table 1 below.

As shown in Table 1, the coating layer prepared from the antireflective coating composition of Example 1 showed an improved line width CD as compared with the coating layers obtained in Comparative Examples 1 and 2. Therefore, when the photoacid generator as used in the composition of Example 1 is employed, the antireflection coating layer used in the lithography process involving negative tone development can exhibit improved properties.

It is apparent that various modifications of the above-described exemplary embodiments of the present invention can be made without departing from the scope of the invention. Accordingly, the intention is to cover all such modifications that are within the scope of the appended claims and their equivalents.

Claims (10)

A method for forming a pattern by negative tone development, comprising the steps of: (1) forming an anti-reflective coating composition comprising (a) an organic polymer, (b) a photoacid generator, and (c) a crosslinking agent on a substrate. (2) forming a photoresist composition layer on the anti-reflective coating composition layer; (3) simultaneously exposing the photoresist composition layer and the anti-reflective coating composition layer to activating radiation, Thereafter baking; and (4) developing the exposed photoresist composition layer with an organic solvent developer. The method of claim 1, wherein the photoacid generator is an osmium salt photoacid generator. The method of claim 2, wherein the onium salt is a salt having an aromatic group and a sulfonate. The method of claim 1, wherein the anti-reflective coating composition comprises 0.01 to 15 weight percent (wt%) of the light based on the total weight of the solid content of the anti-reflective coating composition. Acid generator. The method of claim 1, wherein the anti-reflective coating composition comprises a thermal acid generator. The method of claim 5, wherein the thermal acid generator is a benzenesulfonic acid-based thermal acid generator. The method of claim 1, wherein the crosslinking agent is an acetylene urea crosslinking agent. The method of claim 1, wherein the organic polymer comprises: (a-1) at least one unit derived from a cyanurate-based compound having two or more groups selected from a carboxyl group and a carboxyl ester; and (a-2) derived from At least one unit of a glycol or a polyol. The method of claim 1, wherein the photoresist composition comprises a matrix polymer, a photoacid generator, and a solvent, wherein the matrix polymer comprises at least one unit having an acid cleavable protecting group. The method of claim 1, wherein a second anti-reflective coating composition layer different from the anti-reflective coating composition layer is formed on the substrate before the anti-reflective coating composition layer is formed. And the anti-reflective coating composition layer is formed on the second anti-reflective coating composition layer.