Photoresist composition and method for forming photoresist pattern and patterned material layer

Abstract

The invention relates to a photoresist composition and a method for forming a photoresist pattern and a patterned material layer. The photoresist composition includes an organic polymer and a floatable polymer. The floatable polymer has a lower surface energy than the organic polymer. After curing, the floatable polymer forms a surface layer on the photoresist layer formed from the organic polymer. The presence of the surface layer reduces optical flares and chemical flares, thereby improving the critical dimensions of features formed in the material layer below the photoresist layer.

Description

Technical Field

[0001] The present disclosure relates to a photoresist composition and a method for forming a photoresist pattern and a patterned material layer. Background Art

[0002] Integrated circuits are formed on semiconductor wafers. The photolithography patterning process uses ultraviolet light to transfer a mask pattern to a photoresist on the semiconductor wafer. An etching process can then be used to transfer the pattern to the layers below the photoresist. Repeating the process multiple times with different patterns can build up different layers on the wafer substrate and make devices.

[0003] High-resolution lithography processes are needed to achieve smaller feature sizes. An example of one such process is extreme ultraviolet (EUV) lithography, which uses wavelengths of about 10 nanometers (nm) to about 100 nm. However, further improvements are needed. Summary of the invention

[0004] The present disclosure provides a method for forming a photoresist pattern. The method includes the following operations. A substrate is coated with a photoresist composition including an organic polymer and a floatable polymer mixed with the organic polymer, wherein after coating the substrate, the organic polymer forms a photoresist layer on the substrate, and the floatable polymer forms a surface layer on the photoresist layer. The photoresist layer and the surface layer are cured. The photoresist layer is patterned by exposure to radiation. The photoresist layer is developed to form a photoresist pattern.

[0005] The present disclosure also provides a method for forming a patterned material layer. The method includes the following operations. A substrate is coated with a photoresist composition including an organic polymer and a floatable polymer, wherein after coating the substrate, the organic polymer forms a photoresist layer on the substrate, and the floatable polymer forms a surface layer on the photoresist layer. The organic polymer and the surface layer are cured. The photoresist layer is exposed to radiation to pattern the photoresist layer. The coated substrate is optionally subjected to a post-exposure bake. The patterned photoresist layer is developed using a developer. The patterned photoresist layer is optionally hard-baked. The patterned photoresist layer is etched to obtain a patterned material layer on the substrate.

[0006] The present disclosure also provides a photoresist composition, which includes an organic polymer, up to 50 wt% of a floatable polymer, a photoacid generator, a quencher, and a solvent, wherein the surface energy of the floatable polymer is lower than the surface energy of the organic polymer. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The aspects of the present disclosure are best understood from the following detailed description when read in conjunction with the accompanying drawings. It should be noted that, in accordance with standard industry practice, various features are not drawn to scale. In fact, the size of each feature may be arbitrarily increased or decreased for clarity of discussion.

[0008] Figure 1 is a flow chart illustrating a method for preparing a patterned photoresist layer and etching a layer of a semiconductor device according to some embodiments;

[0009] Figure 2A It's the beginning Figure 1 A cross-sectional view of a substrate before the method;

[0010] Figure 2B It's the beginning Figure 1 a cross-sectional view of a substrate having a first material layer on the substrate before the method;

[0011] Figure 2C It's the beginning Figure 1 a cross-sectional view of a substrate having two bottom layers on a first material layer before the method;

[0012] Figure 3 is a cross-sectional view of a substrate having a photoresist layer located above a first material layer and a surface layer located above the photoresist layer;

[0013] Figure 4 is a cross-sectional view of the substrate after exposure to radiation, wherein the photoresist layer now includes soluble regions and insoluble regions;

[0014] Figure 5 is a cross-sectional view of a substrate having a patterned photoresist layer after development;

[0015] Figure 6 is a cross-sectional view of a final structure having a patterned first material layer;

[0016] Figure 7 is a graphical representation of the effect of a surface layer formed by a floatable polymer on subsequent photoresist patterning;

[0017] Figure 8 is an illustration of an extreme ultraviolet (EUV) lithography system for exposing a photoresist layer to EUV radiation according to some embodiments;

[0018] Fig. 9 are images of experimental examples in which no floatable polymer was used in the photoresist composition;

[0019] Fig.10 are images of experimental examples of photoresist compositions containing floatable polymers.

[0020]

Explanation of symbols

[0021] 100: Method

[0022] 105: Steps

[0023] 110: Steps

[0024] 120: Steps

[0025] 122: Steps

[0026] 130: Steps

[0027] 132: Steps

[0028] 140: Steps

[0029] 150: Steps

[0030] 160: Steps

[0031] 170: Steps

[0032] 200:Substrate

[0033] 202: First material layer

[0034] 204: Lower level

[0035] 206: Upper bottom

[0036] 210: Photoresist layer

[0037] 211: Surface layer

[0038] 212: Soluble area

[0039] 214: Insoluble area

[0040] 215:Thickness

[0041] 702: Mask

[0042] 800:EUV lithography system

[0043] 840:EUV light source

[0044] 850: Lighting arc segment

[0045] 852: Field Faceted Mirror

[0046] 854: Relay mirror

[0047] 860: Photomask

[0048] 862:Thin film

[0049] 870: Projection Optical Module

[0050] 872: Illustrative Mirror

[0051] 874: Illustrative Mirror

[0052] Q: Quencher DETAILED DESCRIPTION

[0053] The following disclosure provides many different embodiments or examples for implementing different features of the provided subject matter. Specific examples of components and arrangements are described below to simplify the present disclosure. Of course, these are merely examples and are not intended to be limiting. For example, forming a first feature above or on a second feature in the following description may include an embodiment in which the first feature and the second feature are formed to be in direct contact, and may also include an embodiment in which an additional feature may be formed between the first feature and the second feature so that the first feature and the second feature may not be in direct contact. In addition, the present disclosure may repeat reference numbers and / or letters in various examples. This repetition is for the purpose of simplicity and clarity, and does not itself dictate the relationship between the various embodiments and / or configurations discussed.

[0054] Additionally, spatially relative terms, such as "beneath," "below," "lower," "above," "upper," and the like, may be used herein to facilitate describing the relationship of one element or feature to another element or feature, as exemplified in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, the device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative terms used herein may be interpreted accordingly.

[0055] The numerical values ​​in the specification and claims of the present disclosure should be understood to include the same numerical values ​​when reduced to the same number of significant figures and the numerical values ​​that differ from the numerical values ​​by less than the experimental error of the type of conventional measurement technology used to determine the numerical values ​​described in the present disclosure. All ranges disclosed herein include the listed endpoints.

[0056] The term "about" can be used to include any numerical value that does not change the basic function of the numerical value even if it is changed. When used with a range, "about" also discloses a range defined by the absolute values ​​of the two endpoints, for example, "about 2 to about 4" also discloses a range of "2 to 4". The term "about" can be ±10% of the specified number.

[0057] The present disclosure may be about the temperature in certain method steps. It should be noted that these references refer to the temperature at which the heat source is set, and not specifically to the temperature that the particular material exposed to the heat must reach.

[0058] The term "ambient temperature" or "room temperature" refers to a temperature of 15°C to 30°C.

[0059] The present disclosure relates to structures composed of different layers. When the terms "on" or "upon" are used to refer to two different layers (including a substrate), they simply mean that one layer is located on or above another layer. These terms do not require that the two layers are in direct contact with each other, and allow other layers to be located between the two layers. For example, all layers of a structure can be considered to be "on" a substrate, even if they are not all in direct contact with the substrate. The term "directly" can be used to indicate that two layers are in direct contact with each other without any layers in between. In addition, when it is mentioned that a process step is performed on a substrate, this should be understood according to the context as also performing such a step on any layer that may be present on the substrate.

[0060] As used herein, the term "copolymer" refers to a polymeric molecule derived from two or more monomers, in contrast to a homopolymer, which is a molecule derived from only one monomer. The term "dipolymer" refers to a molecule derived from only two different monomers. The term "terpolymer" refers to a molecule derived from only three different monomers. The term "tetrapolymer" refers to a molecule derived from only four different monomers.

[0061] The terms "monomer" and "repeating unit" are used interchangeably herein. Repeating units are derived from monomers, and their structures are known and varied.

[0062] The term "alkyl" refers to a fully saturated group consisting entirely of carbon atoms and hydrogen atoms (i.e., containing no double or triple bonds). Alkyl groups can be straight chain, branched, and / or cyclic. Alkyl groups can be bonded to one or two other atoms, depending on the context in which the term is used. For example, methyl (-CH3) and methylene (-CH2-) should be considered alkyl groups. As used herein, an alkyl group can contain 1 to 8 carbon atoms.

[0063] The term "aryl" refers to an aromatic group consisting entirely of carbon atoms and, if appropriate, hydrogen atoms along the periphery of the group. As used herein, an aryl group may have from 6 to about 18 carbon atoms. The term "aryl" should not be construed to include substituted aromatic groups, such as methylphenyl (7 carbon atoms). Aromatic groups may be bonded to one or two other atoms, depending on the context in which the term is used. For example, phenyl (-C6H5) and phenylene (-C6H4-) should be considered aromatic groups.

[0064] The term "heteroaryl" refers to a cyclic group consisting of carbon atoms, hydrogen atoms and heteroatoms within the ring of the group, and the cyclic group is aromatic. The heteroatom may be nitrogen, sulfur or oxygen. Exemplary heteroaryl groups include thienyl, pyridyl, furyl, pyrrolyl, indolyl and quinolyl. When describing heteroaryl groups in conjunction with a numerical range of carbon atoms, heteroaryl groups should not be interpreted as including substituted heteroaromatic groups. Depending on the context, heteroaryl groups can form single bonds with one or two different non-hydrogen atoms. For example, the groups -C4H3S and -C4H2S- can both be referred to as thienyl groups and should both be considered heteroaryl groups. As used herein, heteroaryl groups have 5 to about 18 carbon atoms.

[0065] The term "ester" refers to a group of formula -CO-O-.

[0066] The term "carboxyl" refers to a group of the formula -CO-OR" where R" is hydrogen or alkyl, and also to salts thereof. The carboxyl group is bonded via a carbon atom. It should be noted that a carbonate group (-O-CO-OR") should not be considered a carboxyl group.

[0067] The term "hydroxyl" refers to an -OH group.

[0068] The term "amino" refers to a group of the formula -NR 1 R 2 A group in which R 1 and R 2 is independently hydrogen or alkyl. This includes monosubstituted groups (i.e., groups in which R 2 is hydrogen) and a disubstituted group (where R 1 and R 2 are not hydrogen). When R 1 and R 2 When it is an alkyl group, the alkyl chain may be substituted by a fluorine atom.

[0069] The term "alkoxy" refers to an alkyl group attached to an oxygen atom, i.e., -OC n H 2n+1 .

[0070] The term "alkylthio" refers to an alkyl group attached to a sulfur atom, i.e., -SC n H 2n+1 .

[0071] The term "sulfhydryl" refers to a -SH group.

[0072] The term "acylamido" refers to a group of the formula -N(R 1 )-CO-R 2 A group in which R1 and R 2 is independently hydrogen, alkyl, substituted alkyl, aryl or substituted aryl. The amide group is bonded through the nitrogen atom.

[0073] The term "acyloxy" refers to a radical of the formula -O-CO-R, wherein R is hydrogen, alkyl, substituted alkyl, aryl or substituted aryl, and also to salts thereof. The acyloxy radical is bonded via an oxygen atom.

[0074] The term "nitro" refers to the radical -NO2.

[0075] The term "cyano" refers to a group of formula -CN.

[0076] The term "halogen" refers to a fluorine (F), chlorine (Cl), bromine (Br) or iodine (I) atom.

[0077] The term "nitroso" refers to a group of formula -N=O.

[0078] The term "acyl" refers to a radical of the formula -CO-R, wherein R is hydrogen, alkyl, substituted alkyl, aryl or substituted aryl, and also to salts thereof. The acyl radical is bonded through a carbon atom.

[0079] The term "sulfite" refers to a radical of the formula -SO3R, wherein R is hydrogen, alkyl, substituted alkyl, aryl or substituted aryl, and also to salts thereof. The acyl group is bonded via a carbon atom.

[0080] The term "β-dicarbonyl" refers to a radical of the formula -CO-CR 1 R 2 -CO-R 3 A group in which R 1 , R 2 and R 3 is independently hydrogen, alkyl, substituted alkyl, aryl or substituted aryl, and also refers to salts thereof.

[0081] The term "imide" refers to a molecule of the formula -CO-NR 1 -CO-R 2 A group in which R 1 and R 2 is independently hydrogen, alkyl, substituted alkyl, aryl or substituted aryl, and also refers to salts thereof.

[0082] The term "sulfonamide" refers to a sulfonamide of the formula -SO2-NR 1 R 2 A group in which R1 and R 2 is independently hydrogen, alkyl, substituted alkyl, aryl or substituted aryl, and also refers to salts thereof.

[0083] The term "sulfonyl" refers to a radical of the formula -SO2-R, wherein R is hydrogen or alkyl.

[0084] The term "sulfonylurea" refers to a sulfonylurea of ​​the formula -SO2-NR 1 -CO-NR 2 R 3 Or -NR 1 -CO-NR 2 -SO2R 3 A group in which R 1 , R 2 and R 3 is independently hydrogen, alkyl, substituted alkyl, aryl or substituted aryl, and also refers to salts thereof.

[0085] The term "tetrazole" is a group -CHN4, which is a heterocyclic group.

[0086] The term "phosphate" refers to -PO4 3- The group.

[0087] The term "phosphonate" refers to a group of the formula -PO(OR)2, wherein each R is independently hydrogen, alkyl, substituted alkyl, aryl or substituted aryl, and also refers to salts thereof.

[0088] The term "sulfate" refers to -SO4 2- The group.

[0089] The term "substituted" refers to at least one hydrogen atom on a designated group being replaced by another functional group. An exemplary substituted alkyl group is a perhaloalkyl group, in which one or more hydrogen atoms in the alkyl group are replaced by a halogen atom. The alkyl group may be substituted by a hydroxyl or a halogen group. An aryl or heteroaryl group may be substituted by an alkyl group, a substituted alkyl group, a hydroxyl group, and / or a halogen group.

[0090] The term "up to X" is used in this disclosure to indicate the amount of a given material. The term should be interpreted as requiring that the given material be present in an amount greater than zero, or in other words, excluding the value of zero.

[0091] The present disclosure is about the pKa values ​​of various components. The pKa values ​​are measured in water systems according to known methods.

[0092] The present disclosure relates to photoresist compositions and methods for using such compositions in lithography processes for manufacturing integrated circuits / semiconductor devices. In this regard, the photoresist composition is applied to a substrate, for example, by spin coating, and may also be cured by baking. The photoresist contains a photosensitive material. A patterned mask is used to cover portions of the photoresist and expose portions of the photoresist to radiation, such as ultraviolet light or an electron beam. The photoresist is then developed using a chemical solution (referred to as a developer). The developer removes portions of the photoresist (i.e., the exposed portions in a positive photoresist or the unexposed portions in a negative photoresist), thereby transferring the mask pattern to the photoresist layer. The patterned photoresist layer can then be used as an etching mask for a subsequent etching process to transfer the pattern to the material layer below.

[0093] The minimum feature size of the pattern can be affected by the wavelength of light. Deep ultraviolet (UV) lithography uses wavelengths of 193nm or 248nm. Extreme ultraviolet (EUV) light has a wavelength range of 124 nanometers (nm) to 10nm and is currently used to provide smaller minimum feature sizes. At such wavelengths, photosensitive materials need to use light as efficiently as possible. Chemical amplification can be used to improve photoresist efficiency. In chemically amplified resists (or chemically amplified resists, CARs), the photoresist composition includes a photosensitive polymer, a photoacid generator (PAG) and a quencher. After exposure to radiation, the PAG produces an acid. The acid cleaves the acid labile group (ALG) on the polymer to change the solubility of the polymer. This also produces an acid that can continue to react. This chain reaction will only stop when the generated acid comes into contact with a base (also called a quencher). The balance between the acid and the quencher determines the fidelity of the photoresist pattern, such as whether the sidewalls are straight.

[0094] The photoresist composition disclosed herein includes an organic polymer (or resin) and a floatable polymer having a lower surface energy than the organic polymer. Due to the difference in surface energy, the organic polymer and the floatable polymer will spontaneously separate into two different layers during deposition and curing. The organic polymer forms a photoresist layer, and the floatable polymer "rises" to form a surface layer on the photoresist layer. The surface layer can absorb out-of-band (OOB) radiation, reduce optical flare (i.e., unwanted light reaching the substrate), thereby resulting in an increase in the critical dimension (CD) of the groove and a decrease in the line CD in the positive tone development (PTD) process. The surface layer can also reduce or prevent outgassing, thereby reducing chemical flare, and further reducing positive tone development (PTD) and / or scum in the exposed area. The photoresist composition may further include a photoacid generator (PAG), a quencher Q, and a solvent.

[0095] The surface energy of the buoyant polymer is lower than that of the organic polymer forming the light-blocking layer. The surface energy of each polymer can be measured by their contact angle using methods known in the art. In a specific embodiment, the contact angle of the buoyant polymer is about 75 degrees (°) to about 90°. For comparison, the contact angle of an organic polymer is typically about 60° to about 75°.

[0096] The buoyant polymer may be a homopolymer or a copolymer derived from two or more monomers. The buoyant polymer contains a main chain with side groups or side chains extending therefrom. The main chain of the buoyant polymer is typically a hydrocarbon chain, for example formed by polymerization of vinyl groups present in the monomers forming the buoyant polymer. However, other main chain structures of the buoyant polymer are also contemplated. For example, the buoyant polymer may also have a polyester, polycarbonate or polyamide main chain. In terms of stereochemistry, the buoyant polymer may be isotactic, atactic or syndiotactic.

[0097] Typically, the buoyant polymer contains fluorine atoms in order to reduce the surface energy of the buoyant polymer relative to the organic polymer. The surface energy reduction is typically proportional to the number of fluorine atoms in the buoyant polymer.

[0098] In some embodiments of the present disclosure, the buoyant polymer is a homopolymer having the general structure shown in Formula (I):

[0099]

[0100] Wherein the monomer consists of moieties B1, L1 and P1, wherein B1 forms part of the backbone; L1 is a linking group, and P1 is a side group. In a specific embodiment, at least five fluorine atoms are present in the monomer of the homopolymer. Up to 12 fluorine atoms may be present. In additional embodiments, the pKa value of the monomer is less than 13.

[0101] In some specific embodiments, B1 has the general formula (B-1):

[0102]

[0103] wherein R1, R2 and R3 are independently hydrogen, alkyl or alkyl substituted with fluorine atoms; the wavy line indicates the connection to the linking group L1. In more specific embodiments contemplated herein, R1, R2 and R3 are hydrogen.

[0104] In a specific embodiment, the linking group L1 may be an alkyl group which may be substituted by fluorine; an alkoxy group which may be substituted by fluorine; a cycloalkyl group which may be substituted by fluorine; an aryl group which may be substituted by fluorine; a heteroaryl group which may be substituted by fluorine; an ester; a sulfonyl group; or -O-. In a more specific embodiment, L1 is a cycloalkyl group; an aryl group; an ester; or -O-. Specific examples of L1 may include phenyl (-C6H4-) or cyclohexyl (-C6H 10 -).

[0105] The side group P1 may be an alkyl or substituted alkyl group; a carboxyl group; a hydroxyl group; an aryl or substituted aryl group; or an amine group. Specific examples of P1 include -CH(CF3)(CF2OH); -C(CF3)2OH; -CH2CH(CF3)(CF2OH); -COOH; or -OH. The side group P1 may be a fluoroalcohol group. In specific embodiments, the side group P1 contains up to four carbon atoms.

[0106] It should be noted that if there is any ambiguity in the structure of a particular monomer, the structure should be interpreted so that B1, L1, and P1 are all present. For example, 4-vinylbiphenyl should be interpreted as B1 = vinyl; L1 = phenyl (-C6H4); and P1 = phenyl (-C6H5).

[0107] In other embodiments of the present disclosure, the buoyant polymer is a copolymer, which may be formed from two, three, four, five or more different monomers. When the buoyant polymer is a copolymer, the copolymer is typically a random copolymer.

[0108] Some specific copolymer examples of buoyant polymers are shown in the following formulas (II) and (III):

[0109]

[0110] wherein M1, M2 and M3 are different repeating units / monomers respectively; wherein x is the molar ratio of monomer M1; y is the molar ratio of monomer M2; and z is the molar ratio of monomer M3; and wherein in formula (II), x+y=1; and in formula (III), x+y+z=1.

[0111] Monomer M1 can be considered as a first monomer type, monomer M2 can be considered as a second monomer type, and monomer M3 can be considered as a third monomer type. Each monomer type is different from the other monomer types, and therefore the copolymers of formula (II) and (III) are also different from each other. All three monomer types contain moieties B1, L1 and P1 as described in conjunction with formula (I) above. However, although the copolymer itself contains fluorine atoms, not all monomers M1-M3 must contain fluorine atoms. In a specific embodiment, when the monomers of the copolymer are considered together, at least five (5) fluorine atoms are present in the monomer (regardless of the relative molar amounts of each monomer). Up to 12 fluorine atoms may be present in the monomer. It should be noted that although a particular monomer may fall within the definition of more than one of monomers M1, M2 and M3 (as will be discussed below), formulas (II) and (III) should be interpreted as requiring the presence of different monomers.

[0112] In specific embodiments of formula (II) and (III), x is from about 0.20 to about 0.80, or in other words, the copolymer contains from about 20 mol % to about 80 mol % of monomer M1. In some more specific monomers, x is 0.30 or greater. However, other values ​​and ranges are also within the scope of the present disclosure.

[0113] In embodiments of formula (II) and (III), y is from about 0.20 to about 0.80, or in other words, the copolymer contains from about 20 mol % to about 80 mol % of monomer M2. However, other values ​​and ranges are also within the scope of the present disclosure.

[0114] In embodiments of formula (II) and (III), z is up to about 0.50, or in other words, the copolymer contains up to about 50 mol % of monomer M3. However, other values ​​and ranges are also within the scope of the present disclosure.

[0115] Reference is now made to monomer type M1, which contains fluorine atoms and has a pKa value of less than 13. In specific embodiments, monomer type M1 contains at least five fluorine atoms, and more particularly may contain 5 to about 12 fluorine atoms. The fluorine atoms are typically present in the side groups P1, but may also be present in the backbone portion B1 or the linking group L1. Monomer type M1 should also be soluble in the developer that will be used to develop the photoresist. Some specific examples of side groups P1 suitable for monomer type M1 include substituted alkyl groups (typically substituted with fluorine). Specific examples of P1 for monomer type M1 include fluoroalcohol groups, such as -CH(CF3)(CF2OH); -C(CF3)2OH; and -CH2CH(CF3)(CF2OH) side groups. In specific embodiments of monomer type M1, side groups P1 contain up to four carbon atoms. For reference, it should be noted that the pKa value of trifluoromethanol (CF3OH) is 2.42; the pKa value of nonafluorotert-butyl alcohol (C4F9OH) is 5.4; and the pKa value of trifluoroethanol (CF3CH2OH) is 12.5.

[0116] Some illustrative examples of repeating units / monomers M1 are shown below in formulae (M1-a) to (M1-c):

[0117]

[0118] Reference is now made to monomer type M2, which also has a pKa value of less than 13. In addition, this monomer type includes functional groups that are soluble in the solvent of the photoresist composition. Monomer type M2 should also be soluble in the developer that will be used to develop the photoresist. If desired, monomer type M2 may contain fluorine atoms. It should be noted that the combination of monomer types M1 and M2 allows the surface layer to act as a top cover layer, thereby preventing the quencher from outgassing from the photoresist layer. Some specific examples of side groups P1 suitable for monomer type M2 include fluoroalcohols, carboxyls, hydroxyls, β-dicarbonyls, imides, sulfonamides, sulfonylureas, tetrazoles, sulfhydryls, phosphates, phosphonates, and sulfates. Some illustrative examples of repeating units / monomers M2 are shown below in formulas (M2-a) and (M2-b):

[0119]

[0120] Referring now to monomer type M3, monomer M3 may have several different functional groups suitable for various applications. For example, monomer M3 may absorb UV wavelengths (i.e., act as a chromophore), act as a quencher, increase etch resistance or reduce etch rate, reduce rounding of the photoresist layer, contain a photoacid generator (PAG) group, or reduce developer swelling. Monomer type M3 encompasses many monomer subtypes, and one or more M3 subtypes may be present in the floatable copolymer.

[0121] A monomer subtype is designated herein as M3-I, and the monomer subtype absorbs UV wavelengths, particularly wavelengths between 100 nanometers (nm) and 400 nm. Monomer subtype M3-I includes at least one aromatic ring. In a specific embodiment, monomer subtype M3-I has a total of one to five aromatic rings (in L1 and P1). If desired, monomer subtype M3-I may also contain fluorine atoms. Some specific examples of side groups P1 suitable for monomer subtype M3-I include phenyl, naphthyl; phenanthrenyl; furanyl; pyridyl; and derivatives thereof. In addition, these side groups may be substituted with electron-pushing groups such as amine, hydroxyl, alkoxy, alkyl, alkylthio, sulfhydryl, amide, acyloxy; and / or electron-withdrawing groups such as nitro, cyano, halogen, nitroso and acyl. Some illustrative examples of repeating units / monomers M3-I are shown below in formulas (M3-a) to (M3-f):

[0122]

[0123] wherein R is an electron donating or electron withdrawing group as described above; and wherein m is 0 to 5.

[0124] It should be noted that formula (M3-b) should be considered as having a total of three aromatic rings, rather than just two aromatic rings, because the naphthyl group itself has two aromatic rings and should not be considered as having only one aromatic ring.

[0125] Reference is now made to monomer subtype M3-II, which contains a functional group having a pKa value higher than the pKa value of the acid generated by the photoacid generator (PAG) of the photoresist composition. PAGs typically generate acids with a pKa value less than 1. Monomer subtype M3-II can be considered to act as a quencher to neutralize the acid at the surface of the exposed area of ​​the photoresist layer. This reduces the acid concentration at the surface, thereby reducing or preventing rounding at the surface of the photoresist layer. In other embodiments, monomer subtype M3-II has a functional group with a pKa value greater than -10. When the functional group is an ion, the conjugate acid of the pKa value should be used. Some specific examples of side groups P1 suitable for monomer subtype M3-II include amine, carboxyl and sulfite. Phenyl, naphthyl; phenanthrenyl; furanyl; pyridyl; and derivatives thereof. In other embodiments, the side group P1 includes a nitrogen atom having unpaired electrons capable of neutralizing the acid. Some illustrative examples of repeating units / monomers M3-II are shown below in formulas (M3-g) to (M3-j):

[0126]

[0127] Where R 1 and R 2 is as defined above for the amine group, and TPS is the triphenylsulfonium cation.

[0128] Secondly, monomer subtypes M3-III and M3-IV are always used together. They improve the etch resistance of the floatable polymer and the resulting surface layer, and also reduce the rounding of the photoresist layer. In a specific embodiment, the molar ratio of monomers M3-III to M3-IV is about 2:1 to about 1:2.

[0129] The monomer subtype M3-III contains an acid labile group (ALG) which cleaves upon exposure to acid. This cleavage causes the floatable polymer to become more hydrophilic. ALGs are well known in the art. Thus, the monomer subtype M3-III provides chemical amplification. In some embodiments, the ALG contains inorganic atoms such as silicon, phosphorus or sulfur. Some specific examples of side groups P1 suitable for monomer subtype M3-III are illustrated in the non-limiting examples of repeating units / monomers shown below in formulas (M3-k) and (M3-1):

[0130]

[0131] The monomer subtype M3-IV contains a metal coordination complex having a ligand and a metal atom. The metal atom can be any metal or transition metal atom, such as Ti, Fe, Sn, V, Cr, Co, Ni, Zn, Sb, Al, Pt, W, Zr, Mo, Pd or Ag. Some specific examples of side groups P1 suitable for monomer subtype M3-IV are shown in the non-limiting examples of repeating units / monomers shown in the following formulas (M3-m) to (M3-o):

[0132]

[0133] Continuing, monomer subtype M3-V contains a photoacid generating (PAG) side group. In this monomer subtype, the linking group L1 can also be a single bond. In some embodiments, the side group P1 includes a phenyl ring. In some embodiments, the PAG side group includes a halogenated triazine, an onium salt, a diazonium salt, an aromatic diazonium salt, a phosphonium salt, a sulfonium salt, an iodonium salt, an imidosulfonate, an oximesulfonate, a diazodisulfone, a disulfone, an o-nitrobenzylmethylsulfonate, a sulfonated ester, a halogenated sulfonyloxydiformimide, a diazodisulfone, an α-cyanoamine sulfonate, an imidosulfonate, a ketonediazosulfone, a sulfonyldiazoester, a 1,2-di(arylsulfonyl)hydrazine, a nitrobenzyl ester, and / or a s-triazine derivative. In some embodiments, the PAG side group includes a triarylsulfonium group, a diaryliodonium group, a trifluoromethanesulfonate group, or an iodoniumsulfonate group.

[0134] Finally, monomer subtype M3-VI contains pendant groups that mitigate swelling in the developer, particularly when the developer is an aqueous solvent such as TMAH. An example of such a pendant group is a lactone.

[0135] As described above, more than one subtype of monomer M3 can be present in the copolymer at the same time. Referring back to formula (III), when more than one subtype is present, the subtypes are combined together to determine the molar ratio z. In some other embodiments, when more than one subtype is present, each subtype is present in an amount of at least 1 mol%.

[0136] The buoyant polymer may be prepared from suitable monomers using conventional polymerisation techniques. Any suitable step-growth or chain-growth polymerisation process may be used, such as addition polymerisation, free radical polymerisation, condensation polymerisation, emulsion polymerisation, solution polymerisation, suspension polymerisation or precipitation polymerisation.

[0137] The floatable polymer is a component of the photoresist composition. Other components of the photoresist composition include an organic polymer, a photoacid generator (PAG), a quencher, and a solvent. In a specific embodiment, the floatable polymer is up to 50 wt % in the photoresist composition. Other optional additives such as surfactants, sensitizers, crosslinkers, stabilizers, dissolution inhibitors, plasticizers, colorants, adhesion promoters, and / or surface leveling agents may also be present in the photoresist composition.

[0138] In a specific embodiment, the organic polymer is a positive photoresist, which is photosensitive and degrades by exposure to radiation. Thus, the developer will dissolve the areas exposed to light. Such positive photoresists are well known. In other embodiments contemplated herein, the organic polymer is a negative photoresist. The floatable copolymer is compatible with both types of photoresists.

[0139] Non-limiting examples of PAGs may include halogenated triazines, onium salts, diazonium salts, aromatic diazonium salts, phosphonium salts, sulfonium salts, iodonium salts, imide sulfonates, oxime sulfonates, diazodisulfones, disulfones, o-nitrobenzylsulfonates, sulfonated esters, halosulfonyloxydicarboximides, diazodisulfones, α-cyanoamine sulfonates, imide sulfonates, ketonediazosulfones, sulfonyldiazoesters, 1,2-bis(arylsulfonyl)hydrazines, nitrobenzyl esters, and s-triazine derivatives, combinations of these, or the like.

[0140] Specific examples of PAG include α-(trifluoromethylsulfonyloxy)-bicyclo[2.2.1]hept-5-ene-2,3-dicarboximide (MDT); N-hydroxynaphthalene imide (DDSN); benzoin tosylate; tert-butylphenyl-α-(p-toluenesulfonyloxy)-acetate; tert-butyl-α-(p-toluenesulfonyloxy)-acetate; triarylsulfonium and diaryliodonium hexafluoroantimonates; hexafluoroarsenates; trifluoromethanesulfonates; iodonium perfluorooctanesulfonate; N-camphorsulfonyloxynaphthalimide; N-pentafluorobenzenesulfonyloxynaphthalimide; ionic iodonium sulfonic acid salts such as diaryliodonium (alkyl or aryl) sulfonates and bis(di-tert-butylphenyl)iodonium camphenyl sulfonates; perfluoroalkane sulfonates such as perfluoropentane sulfonates, perfluorooctane sulfonates or perfluoromethane sulfonates; aryl triflates such as triphenylsulfonium triflates or bis(tert-butylphenyl)iodonium triflates; pyrogallol derivatives (e.g., pyrogallol trimesylate); triflates of hydroxyimides; α,α'-bissulfonyldiazomethane; sulfonates of nitro-substituted benzyl alcohols; naphthoquinone-4-diazide; ethyl ketones; and alkyl disulfones.

[0141] Quenchers can be used to inhibit the diffusion of the generated acid in the photoresist, thereby improving the stability of the photoresist and also improving the structure of the resist pattern. Non-limiting examples of quenchers include amines and organic acids. The amine can be a second lower aliphatic amine or a lower aliphatic tertiary amine. Specific examples of amine quenchers include trimethylamine; diethylamine; triethylamine; di-n-propylamine; tri-n-propylamine; tripentylamine; diethanolamine; triethanolamine; and other alkanolamines.

[0142] Examples of organic acids that can be used as quenchers may include malonic acid; citric acid; malic acid; succinic acid; benzoic acid; oxalic acid; phosphoric acid and its derivatives, such as di-n-butyl phosphate or diphenyl phosphate; phosphonic acid and its derivatives, such as dimethyl phosphonate, di-n-butyl phosphonate; phenylphosphonic acid, diphenyl phosphonate or dibenzyl phosphonate; phosphinic acid and its derivatives, such as its esters or phenylphosphinic acid.

[0143] The various components are mixed or blended together in a solvent to form a photoresist composition. In a specific embodiment, the solvent is an organic solvent. Examples of suitable organic solvents include propylene glycol monomethyl ether (PGME), propylene glycol methyl ether acetate (PGMEA), and a mixture of PGME and PGMEA commercially known as OK73. Other examples include ketones, alcohols, polyols, ethers, glycol ethers, cyclic ethers, aromatic hydrocarbons, esters, propionates, lactic acid, lactic acid esters, alkylene glycol monoalkyl ethers, alkyl lactates, alkyl alkoxypropionates, cyclic lactones, cyclic monoketone compounds, alkylene carbonates, alkylene alkoxy acetates, alkylene pyruvates, lactates, ethylene glycol alkyl ether acetates, diethylene glycol, propylene glycol alkyl ether acetates, alkylene glycol alkyl ether esters, alkylene glycol monoalkyl esters or the like.

[0144] A surfactant may be present in the photoresist composition. After development, the surfactant may facilitate the removal of residues from the photoresist layer. The surfactant may be an alkyl cationic surfactant, an amide-type quaternary ammonium cationic surfactant, an ester-type quaternary ammonium cationic surfactant, an amine oxide surfactant, a betaine surfactant, an alkoxylate surfactant, a fatty acid ester surfactant, an amide surfactant, an alcohol surfactant, an ethylenediamine surfactant, or a fluorine- and / or silicon-containing surfactant.

[0145] Sensitizers may be present in the photoresist composition. When irradiated, the sensitizer is designed to produce radiation of different wavelengths, so that the sensitivity of the photoresist material is significantly improved. In some embodiments, the sensitizer may include fluorine, metal or phenol groups. For example, the sensitizer may be polyhydroxystyrene (PHS) or polyfluorostyrene. Other sensitizers with high electron beam cross-sections may also be used, such as organic iodides, organic bromides, organic chlorides or magnesium-containing compounds.

[0146] A crosslinking agent may also be added to the photoresist composition. The crosslinking agent may react with the organic polymer after exposure, helping to increase the crosslinking density of the photoresist, thereby helping to improve the photoresist pattern and etching resistance. Examples of the crosslinking agent may include melamine, urea, glycoluril compounds, aliphatic hydrocarbons having hydroxyl groups or thiol or hydroxyalkyl groups, alcohols, and etherified amino resins.

[0147] Stabilizers may be included in the photoresist composition. Stabilizers reduce the diffusion of acids generated during exposure of the photoresist composition. Examples of stabilizers include nitrogen-containing compounds such as aliphatic primary, secondary, and tertiary amines; cyclic amines such as piperidine, pyrrolidine, and morpholine; aromatic heterocycles such as pyridine, pyrimidine, and purine; imines; guanidines; imides; amides; ammonium salts; cationic nitrogen-containing compounds; phenolates; carboxylates; aryl and alkyl sulfonates; sulfonamides; and the like.

[0148] Dissolution inhibitors may be included in the photoresist composition to help control the dissolution of the photoresist during development. Non-limiting examples of dissolution inhibitors include cholic acid, deoxycholic acid, lithocholic acid, deoxycholic acid tertiary butyl ester, lithocholic acid tertiary butyl ester, and 3-α-acetyllithocholic acid tertiary butyl ester.

[0149] Plasticizers can be used in photoresist compositions to reduce delamination and cracks between photoresist and the lower layer on which the photoresist layer is formed. Examples of plasticizers can include monomeric, oligomeric and polymeric plasticizers, such as oligoethylene glycol ethers and polyethylene glycol ethers, alicyclic esters and non-acid reactive steroid derivative materials. Specific examples of materials that can be used for plasticizers include dioctyl phthalate, didodecyl phthalate, triethylene glycol dioctanoate, dimethyl phthalate, tricresyl phosphate, dioctyl adipate, dibutyl sebacate, triacetyl glycerol and the like.

[0150] If necessary, a colorant may be used to help locate defects in the photoresist. The broad categories of colorants include dyes and pigments. More specific examples of colorants may include triarylmethane dyes, crystal violet, methyl violet, ethyl violet, malachite green, diamond green, phthalocyanine pigments, azo pigments, carbon black, titanium oxide, benzophenone compounds; phthalic acid compounds; phenyl acrylate compounds; coumarin compounds; thioxanthone compounds; stilbene compounds; naphthalene dicarboxylic acid compounds; azo dyes; and the like.

[0151] Adhesion promoters may be used in the photoresist composition to promote adhesion between the photoresist and an underlying layer on which the photoresist layer is formed. Examples of adhesion promoters include silane compounds having at least one reactive substituent such as a carboxyl group, a methacryloyl group, an isocyanate group, and / or an epoxy group.

[0152] A surface leveling agent may be added to the photoresist composition for leveling the top surface of the photoresist layer. Examples of surface leveling agents include fluoroaliphatic esters, hydroxyl-terminated fluorinated polyethers, fluorinated glycol polymers, silicones, and acrylic polymer leveling agents.

[0153] The photoresist composition is used to form a photoresist layer, which is used in various methods of forming various structures in integrated circuits or semiconductor devices. Figure 1 One such method 100 for forming a photoresist pattern and patterning a material layer in a semiconductor device is described in .

[0154] Initially, it may be necessary to heat the substrate before starting the photoresist patterning process. This can improve resist adhesion by desorbing water present on the substrate surface and thermally cleaving any hydroxide bonds present on the oxidized surface. The substrate may be heated to a temperature above 100°C, up to, for example, 200°C, for a period of several minutes. The substrate is then cooled back to room temperature.

[0155] In step 105, the photoresist composition is applied to the substrate. It should be noted that the substrate can be any type of material layer that needs to be patterned. The coating can be completed, for example, by spin coating, or by spraying, roller coating, dip coating or extrusion coating. Usually, in spin coating, the substrate is placed on a rotating platen, which may include a vacuum chuck that fixes the substrate in the plate. The photoresist composition is then applied to the center of the substrate. The speed of the rotating platen is then increased so that the photoresist is evenly spread to the periphery of the substrate from the center of the substrate. The rotating speed of the fixed platen is then fixed, thereby the thickness of the final photoresist layer can be controlled.

[0156] In step 110, the photoresist composition is baked or cured to remove the solvent and harden the photoresist layer. In some specific embodiments, baking is performed at a temperature of about 80°C to about 130°C and for a period of about 60 seconds. Baking can be performed using a hot plate or an oven or similar equipment.

[0157] As a result of these steps, the floatable polymer "floats" to the top of the photoresist composition. A photoresist layer is formed on the substrate, and the floatable polymer forms a surface layer on top of the photoresist layer.

[0158] In step 120, the photoresist layer is patterned by exposure to radiation. Although ultraviolet ("UV") radiation is currently commonly used, the radiation can be any wavelength of light that carries the desired mask pattern. UV radiation has a wavelength in the range of about 10 nanometers ("nm") to about 400 nm, such as from a KrF laser (248 nm) or an ArF laser (193 nm). In a specific embodiment, extreme ultraviolet ("EUV") light with a wavelength of about 13.5 nm is used for patterning because this allows for smaller feature sizes. In other embodiments, electron beam radiation is used. This results in some portions of the photoresist layer being exposed to radiation, while some portions of the photoresist layer are not exposed to radiation. This exposure activates the organic polymer so that some portions of the photoresist will be soluble in the developer, while some portions of the photoresist will be insoluble in the developer.

[0159] In optional step 122, an additional photoresist bake step (post exposure bake (PEB)) may occur after exposure to radiation. This may help release acid labile groups (ALGs) or other molecules that play an important role in chemical amplification.

[0160] In step 130, the photoresist layer is developed using a developer. The developer can be an aqueous solution or an organic solution. The soluble portion of the photoresist layer is dissolved and washed away during the development step, leaving the photoresist pattern. There are two types of development processes: positive tone development (PTD) and negative tone development (NTD). PTD generally uses a developer that selectively dissolves and removes the exposed portion of the photoresist layer. The NTD process uses a developer that selectively dissolves and removes the unexposed portion of the photoresist layer. In some embodiments, the PTD developer is an aqueous alkaline developer, such as tetramethylammonium hydroxide (TMAH). In some embodiments, the NTD developer is an organic-based developer, such as n-butyl acetate (n-BA), isoamyl acetate (IAA), or other solvents that can dissolve the unexposed portion of the resist layer. In general, any suitable developer can be used.

[0161] In optional step 132, a post-development bake or "hard bake" may be performed to stabilize the photoresist pattern for optimal performance in subsequent steps.

[0162] Continuing, a portion of the material layer below the photoresist pattern is now exposed. In step 140, the material layer is etched so that the exposed portion of the material layer is removed, thereby transferring the photoresist pattern to the material layer. In a specific embodiment, the etching is performed by dry etching.

[0163] In addition to etching of the material layer, other process steps may alternatively be performed. For example, in alternative step 150, ions may be implanted into the exposed material layer, or, as in alternative step 160, a different material may be deposited on the material layer.

[0164] Finally, the photoresist layer may then be removed in step 170. This may be accomplished, for example, at elevated temperature using various solvents such as N-methyl-pyrrolidone (NMP) or alkaline media or other strippers, or by dry etching using oxygen plasma.

[0165] Figures 2A to 6 Draw Figure 1 These figures provide different perspectives for better understanding.

[0166] First reference Figure 2A , which shows an example of the initial state of substrate 200 before any processing steps. The substrate is typically a wafer made of semiconductor material. Such materials may include silicon, for example, silicon in the form of crystalline Si or polycrystalline Si. In alternative embodiments, the substrate may be made of other elemental semiconductors such as germanium, or may include compound semiconductors such as silicon carbide (SiC), gallium arsenide (GaAs), gallium carbide, gallium phosphide, indium arsenide (InAs), indium phosphide (InP), silicon germanium, silicon germanium carbide, gallium arsenic phosphide or gallium indium phosphide. In a specific embodiment, the wafer substrate is silicon. As shown in the figure, there is no additional layer on the substrate 200.

[0167] In contrast, Figure 2B, a first material layer 202 is present on a substrate 200. The first material layer can be any material that can be used in a semiconductor device or an integrated circuit. For example, the first material layer can be made of an insulating material, such as silicon dioxide (SiO2) or silicon nitride (SiN), silicon oxynitride (SiON), fluorine-doped silicate glass, or other dielectric material. As another example, the first material layer can be made of a conductive material, such as polysilicon or a metal such as aluminum, copper, titanium, or tungsten. The first material layer can generally serve any function. For example, the first material layer can be a high-k dielectric layer, a gate layer, a hard mask layer, an interface layer, a capping layer, a diffusion / barrier layer, a dielectric layer (e.g., SiO2), a conductive layer (e.g., doped polysilicon), or some other layer. The following figures show the first material layer as present for illustrative purposes only, and it should be understood that the substrate can also be etched.

[0168] exist Figure 2C In the embodiment of the present invention, one or more underlayers are applied to the substrate before the photoresist composition is applied. In this regard, the term "underlayer" is relative to the photoresist layer and refers to any layer that can be applied to the layer desired to be etched before the photoresist composition is applied. In other words, any layer between the layer to be etched and the photoresist layer can be considered an underlayer. In this illustration, the lower underlayer 204 and the upper underlayer 206 are applied on the first material layer 202.

[0169] As an example, the lower layer 204 may be a bottom anti-reflective coating (BARC). When a photoresist layer is applied to a reflective substrate, light reflection from the substrate / resist interface may produce light exposure variations, resulting in problems with critical dimension (CD) control. For example, light may be reflected to areas that are not intended to be exposed, thereby changing the desired pattern. BARC may be applied between the substrate and the photoresist layer to minimize or eliminate such problems. Examples of suitable BARC include amorphous carbon and various organic polymers. The BARC layer is typically formed by spin coating, but other methods may also be used. The BARC coating or film is then baked or cured to induce crosslinking and solvent removal and BARC hardening. In some specific embodiments, baking is performed at a temperature of about 125° C. to about 275° C. In a specific embodiment, baking is performed for a period of about 30 seconds to about 250 seconds. Baking may be performed using a hot plate or similar equipment.

[0170] As another example, the upper bottom layer 206 may be a hard mask layer. The hard mask layer may be formed of a dielectric material, a metal, or other suitable material. Examples of suitable dielectric materials may include silicon carbide, silicon nitride, silicon oxycarbide, or silicon oxynitride. The hard mask layer may be formed by any suitable process, such as chemical vapor deposition (CVD), low-pressure CVD (LPCVD), plasma-enhanced CVD (PECVD), physical vapor deposition (PVD), atomic layer deposition (ALD), or spin coating. The BARC layer and the hard mask layer are also typically selected to have significantly different etch sensitivities to the same etchant. In combination with the photoresist layer, the multi-layer photoresist pattern may also help improve line width roughness (LWR).

[0171] Now, since Figure 1 Step 105 starts and Figure 3 As shown, a photoresist composition is applied to the substrate and to a material layer such as the upper bottom layer 206. The photoresist composition can be applied, for example, by spin coating, or by spraying, roller coating, dip coating, or extrusion coating. Typically, in spin coating, the substrate is placed on a rotating platen, which may include a vacuum chuck to fix the substrate in the plate. The photoresist composition is then applied to the center of the substrate. The speed of the rotating platen is then increased to evenly spread the photoresist composition from the center of the substrate to the periphery of the substrate. The rotation speed of the platen is then fixed so that the thickness of the final photoresist layer can be controlled. Reference Figure 3 After coating, the photoresist composition is separated into a photoresist layer 210 and a surface layer 211. The photoresist layer 210 may have a thickness 215 of about 10 nm to about 100 nm.

[0172] Next, in Figure 1 In step 110 and still referring to Figure 3 , pre-bake the photoresist composition to remove the solvent and harden the photoresist layer and the surface layer. This may also be referred to as soft baking. In some specific embodiments, the pre-bake is performed at the following temperatures: about 40°C to about 130°C, including about 250°C to about 800°C or about 80°C to about 130°C. The pre-bake time depends on the thickness of the photoresist layer and the surface layer. The greater the thickness, the longer the pre-bake time, and in a specific embodiment, it is about 10 seconds to about 10 minutes. Baking can be performed using a hot plate or an oven or similar equipment. The substrate and other layers thereon are then cooled to room temperature.

[0173] Continue, in Figure 1In step 120, the photoresist layer 210 is then patterned by exposure to radiation. The radiation can be any wavelength of light that carries the desired mask pattern. In a specific embodiment, EUV light having a wavelength of about 13.5 nm is used for patterning because this allows for smaller feature sizes to be obtained. In other embodiments, electron beam (e-beam) radiation is used. The electron beam is characterized by the energy of the beam, and in some embodiments, the energy of the beam is in the range of about 5 kilovolts (kV) to about 200 kV. This step causes some portions of the photoresist layer to be exposed to the radiation, while some portions of the photoresist layer are not exposed to the radiation. This exposure causes some portions of the photoresist to remain soluble in the developer, while other portions of the photoresist become insoluble in the developer. Now referring to Figure 4 , the photoresist layer 210 now includes soluble regions 212 and insoluble regions 214. For reference, it should be noted that EUV and electron beam radiation exposures typically occur under vacuum. The surface layer 211 may or may not be affected by the radiation exposure in the same manner as the photoresist layer.

[0174] Depending on the situation, Figure 1 In step 122, a post exposure bake (PEB) occurs after exposure to radiation. The PEB step can be used to complete any crosslinking within the photoresist, or to complete any chemical amplification reactions that may occur. In addition, the PEB step can reduce mechanical stress that may be generated in the previous steps. In some specific embodiments, the PEB occurs at a temperature of about 40°C to about 250°C, including about 100°C to about 250°C or about 90°C to about 150°C. The time for PEB can range from about 10 seconds to about 10 minutes, and can vary depending on the thickness of the photoresist layer and the surface layer.

[0175] Then, in Figure 1 In step 130, the photoresist layer 210 is developed using a developer. The developer may be applied by spin coating, spray coating, or other suitable methods. The soluble portion of the photoresist layer dissolves and washes away during the development step, leaving behind a patterned photoresist layer. This may be accomplished, for example, by spin drying. The resulting structure is Figure 5 As shown in the figure, the soluble area has been washed away to form a patterned photoresist layer. In addition, the surface layer has also been washed away.

[0176] exist Figure 1 In the optional step 132, a post-development bake or "hard bake" may be performed after development. This operation can stabilize the developed photoresist pattern so that optimal performance can be achieved in subsequent steps. In some specific embodiments, the hard bake occurs at a temperature of about 100° C. to about 160° C. The time of the hard bake can range from about 1 minute to about 10 minutes and can vary depending on the thickness of the photoresist layer.

[0177] Then continue, such as Figure 5As shown, the upper bottom layer 206, a portion of the lower bottom layer 204, and the first material layer 202 beneath the patterned photoresist layer are now exposed.

[0178] Then, in Figure 1 In step 140, etching is performed through the patterned photoresist layer to transfer the photoresist pattern through the upper bottom layer 206 and the lower bottom layer 204 to the first material layer 202 and obtain a patterned material layer. It is desirable that the etchants used for different layers are significantly different from the etchants for other layers, thereby improving the LWR in the first material layer. It should be understood that the patterned material layer can be the first material layer or the substrate. In some embodiments, the first material layer is an insulating layer, and the etching pattern can then be filled with a conductive material to form a circuit in the insulating layer. In other alternative embodiments, the first material layer is a conductive layer, and the etching pattern is then filled with an insulating material.

[0179] Generally, these etching steps may be performed using wet etching, dry etching, or plasma etching processes (such as reactive ion etching (RIE) or inductively coupled plasma (ICP) or a combination thereof), as appropriate. The etching may be anisotropic. Depending on the material, the etchant may include carbon tetrafluoride (CF4), hexafluoroethane (C2F6), octafluoropropane (C3F8), fluoroform (CHF3), difluoromethane (CH2F2), fluoromethane (CH3F), trifluoromethane (CHF3), carbon fluoride, nitrogen (N2), hydrogen (H2), oxygen (O2), argon (Ar), xenon (Xe), xenon difluoride (XeF2), helium (He), carbon monoxide (CO), carbon dioxide (CO2), fluorine (F2), chlorine (Cl2), oxygen (O2), hydrogen bromide (HBr), hydrofluoric acid (HF), nitrogen trifluoride (NF3), sulfur hexafluoride (SF6), boron trichloride (BCl3), ammonia (NH3), bromine (Br2), nitrogen trifluoride (NF3), or the like or a combination of various ratios thereof. For example, hydrofluoric acid and ammonium fluoride may be used to wet etch silicon dioxide. Alternatively, silicon dioxide may be dry etched using various mixtures of CHF3, O2, CF4 and / or H2.

[0180] In addition to etching of the first material layer, other process steps may alternatively be performed. For example, in alternative step 150, ions may be implanted into the exposed material layer, or, as in alternative step 160, a different material may be deposited on the material layer.

[0181] Then, in Figure 1In step 170, the patterned photoresist layer 210 is removed. The bottom layer is also removed. Conventional means such as plasma stripping, solvent or chemical-mechanical planarization (CMP) can be used to remove the photoresist layer, the upper bottom layer and the lower bottom layer. The resulting structure is as shown in FIG. Figure 6 As shown, the first material layer 202 has been patterned.

[0182] Adding a floatable polymer to a photoresist composition provides a number of advantages. First, Figure 7 As shown, the surface layer 211 covers the photoresist layer 210 on the substrate 200 during exposure to radiation through the mask 702. The surface layer absorbs out-of-band (OOB) radiation, thereby reducing or preventing the curing of the photoresist in the mask and non-exposed areas that would otherwise occur. After the post-exposure bake, the surface layer 211 also acts as a top layer and prevents the components from outgassing from the photoresist layer (degassing is indicated by an upward arrow and degassing is inhibited by an X on the arrow). This reduces chemical flare. The floatable polymer can also provide enhanced etch resistance and reduce top rounding of the photoresist layer. Therefore, after development, there is no loss of critical dimension (CD) in the photoresist, CD variation in the photoresist is reduced, and the resulting features formed thereby also maintain their CD.

[0183] Figure 8 8 is an illustrative schematic diagram, not drawn to scale, showing various components of an extreme ultraviolet (EUV) lithography system that produces radiation to which the photoresist is exposed. Generally, the EUV lithography system 800 begins with an EUV light source 840 that produces EUV light or radiation. Downstream of the EUV light source is an illumination arc segment 850, where the EUV light can be collected and focused into a beam, such as using a field facet mirror 852 to split the beam into multiple light channels. One or more relay mirrors 854 can then be used to direct these light channels onto the plane of the reticle. The reticle 860 can include a film 862 through which the radiation passes before and / or after contacting the reticle. Downstream of the reticle 860 is a projection optical module 870 for imaging the pattern of the reticle onto the semiconductor wafer substrate 200. The projection optical module 870 can include a refractive optical element or a reflective optical element for carrying an image of the pattern defined by the reticle. An illustrative mirror 872 and an illustrative mirror 874 are shown. The lithography system may include other modules or be integrated or coupled with other modules.

[0184] Additional processing steps may be performed to fabricate the semiconductor device or integrated circuit. Examples of these steps may include ion implantation, deposition of other materials, etching, etc.

[0185] Therefore, some aspects of the present disclosure are about a method for forming a photoresist pattern. The method includes the following operations. A substrate is coated with a photoresist composition including an organic polymer and a floatable polymer mixed with the organic polymer, wherein after coating the substrate, the organic polymer forms a photoresist layer on the substrate, and the floatable polymer forms a surface layer on the photoresist layer. The photoresist layer and the surface layer are cured. The photoresist layer is patterned by exposure to radiation. The photoresist layer is developed to form a photoresist pattern. In some embodiments, the surface energy of the floatable polymer is lower than the surface energy of the organic polymer. In some embodiments, the contact angle of the floatable polymer is from about 75° to about 90° and is higher than the contact angle of the organic polymer. In some embodiments, the floatable polymer includes a first monomer and a second monomer, wherein the first monomer contains a plurality of fluorine atoms and has a pKa value of less than 13, and wherein the second monomer is different from the first monomer and includes a functional group soluble in a solvent of the photoresist composition, and the second monomer has a pKa value of less than 13. In some embodiments, the first monomer includes 5 or more fluorine atoms. In some embodiments, the second monomer includes a carboxylic acid group, a fluoroalcohol group, or a phenol group. In some embodiments, the floatable polymer includes 30 mol% or more of the first monomer, or the floatable polymer includes 20 mol% to 80 mol% of the second monomer. In some embodiments, the floatable polymer further includes a third monomer different from the first monomer and the second monomer, wherein the third monomer includes at least one aromatic ring, or wherein the third monomer contains a functional group having a pKa value higher than the pKa value of the photoacid generator of the photoresist composition or contains a functional group having a pKa value greater than -10. In some embodiments, the third monomer includes up to 5 aromatic rings. In some embodiments, the third monomer absorbs wavelengths between 100nm and 400nm. In some embodiments, the floatable polymer includes up to 50 mol% of the third monomer. In some embodiments, the third monomer includes an -NR2 group, a carboxyl group, or a sulfite group, wherein each R is independently hydrogen or an alkyl group. In some embodiments, the floatable polymer further includes a third monomer and a fourth monomer, wherein the third monomer includes an acid labile group and the fourth monomer includes a metal coordination complex. In some embodiments, the third monomer further includes an inorganic atom. In some embodiments, the molar ratio of the third monomer to the fourth monomer is from about 2:1 to about 1:2. In some embodiments, the buoyant polymer further comprises a third monomer, and the third monomer contains a photoacid generating pendant group or a pendant group that mitigates developer swelling.

[0186] Other aspects of the present disclosure are methods for forming a patterned material layer. The method includes the following operations. A substrate is coated with a photoresist composition including an organic polymer and a floatable polymer, wherein after coating the substrate, the organic polymer forms a photoresist layer on the substrate, and the floatable polymer forms a surface layer on the photoresist layer. The organic polymer and the surface layer are cured. The photoresist layer is exposed to radiation to pattern the photoresist layer. The coated substrate is optionally subjected to post-exposure baking. The patterned photoresist layer is developed using a developer. The patterned photoresist layer is optionally subjected to hard baking. The patterned photoresist layer is etched to obtain a patterned material layer on the substrate. In some embodiments, the floatable polymer is a random copolymer.

[0187] In various embodiments, a photoresist composition is also disclosed. The photoresist composition includes an organic polymer, up to 50 wt% of a floatable polymer, a photoacid generator, a quencher, and a solvent, wherein the floatable polymer has a surface energy lower than that of the organic polymer. In some embodiments, the floatable polymer includes fluorine.

[0188] The methods and apparatus of the present disclosure are further illustrated in the following non-limiting working examples, it being understood that these examples are intended to be illustrative only and the present disclosure is not intended to be limited to the materials, conditions, process parameters, and the like recited herein.

[0189] Examples

[0190] Experiments were conducted to demonstrate the effectiveness of using a floatable polymer in controlling the shape of a photoresist layer.

[0191] First, a photoresist composition is applied that does not contain a floatable polymer. Thus, no surface layer is present during development. Fig. 9 It shows the image of the photoresist layer after development.

[0192] In a second experiment, a photoresist composition containing a floatable polymer was applied. Thus, a surface layer was present during development. Fig.10 It shows the image of the photoresist layer after development. Fig. 9 and Fig.10 It can be seen that the use of a floatable polymer results in a photoresist layer with a more square profile and less rounding on the top.

[0193] The features of several embodiments are summarized above so that those skilled in the art can better understand the aspects of the present disclosure. Those skilled in the art should understand that they can easily use the present disclosure as a basis for designing or modifying other processes and structures to achieve the same purposes and / or advantages as the embodiments described herein. Those skilled in the art should also recognize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they can make various changes, substitutions, and modifications without departing from the spirit and scope of the present disclosure.

Claims

1. A method for forming a photoresist pattern, characterized in that: include: coating a substrate with a photoresist composition comprising an organic polymer and a floatable polymer mixed with the organic polymer, wherein after coating the substrate, the organic polymer forms a photoresist layer on the substrate and the floatable polymer forms a surface layer on the photoresist layer; curing the photoresist layer and the surface layer; patterning the photoresist layer by exposing it to radiation; as well as The photoresist layer is developed to form the photoresist pattern.

2. The method according to claim 1, characterized in that The contact angle of the buoyant polymer is about 75° to about 90° and is higher than the contact angle of the organic polymer.

3. The method according to claim 1, characterized in that The buoyant polymer comprises a first monomer and a second monomer; wherein the first monomer contains a plurality of fluorine atoms and has a pKa value less than 13; and The second monomer is different from the first monomer and includes a functional group soluble in a solvent of the photoresist composition, and the second monomer has a pKa value less than 13.

4. The method according to claim 3, characterized in that The second monomer includes a carboxylic acid group, a fluoroalcohol group or a phenol group.

5. The method according to claim 3, characterized in that wherein the buoyant polymer comprises 30 mol % or more of the first monomer; or The buoyant polymer comprises 20 mol % to 80 mol % of the second monomer.

6. The method according to claim 3, characterized in that wherein the buoyant polymer further comprises a third monomer different from the first monomer and the second monomer; wherein the third monomer comprises at least one aromatic ring; or The third monomer contains a functional group with a pKa value higher than a pKa value of a photoacid generator of the photoresist composition, or contains a functional group with a pKa value greater than -10.

7. The method according to claim 3, characterized in that The buoyant polymer further comprises a third monomer and a fourth monomer, wherein the third monomer comprises an acidic unstable group and the fourth monomer comprises a metal coordination complex.

8. A method for forming a patterned material layer, characterized in that: include: coating a substrate with a photoresist composition comprising an organic polymer and a floatable polymer, wherein after coating the substrate, the organic polymer forms a photoresist layer on the substrate and the floatable polymer forms a surface layer on the photoresist layer; curing the organic polymer and the surface layer; exposing the photoresist layer to radiation to pattern the photoresist layer; Optionally performing a post-exposure bake on the coated substrate; Using a developer to develop the patterned photoresist layer; Optionally performing a hard bake on the patterned photoresist layer; as well as The patterned photoresist layer is etched to obtain the patterned material layer on the substrate.

9. The method according to claim 8, characterized in that The buoyant polymer is a random copolymer.

10. A photoresist composition, characterized in that: include: an organic polymer; Up to 50 wt % of a buoyant polymer; a photoacid generator; a quencher; as well as A solvent; A surface energy of the buoyant polymer is lower than a surface energy of the organic polymer.

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