Photoresist composition and metallization method

Abstract

The invention discloses a photoresist composition and a metallization method. The photoresist composition comprises a polymer comprising a first repeating unit having formula (3) and a second repeating unit having formula (4): wherein: R1 is a hydrogen atom or a substituted or unsubstituted C1-C3 alkyl group; z is a non-hydrogen substituent comprising an acid labile moiety; wherein m and n are numbers of repeating units of the first repeating unit and the second repeating unit, respectively; a compound having formula (6): wherein: R2 is independently a C1-C3 alkyl group or a C1-C3 alkoxy group; and p is an integer from 0 to 4; a photoacid generator; and a solvent. # imgabs0 #

Description

Background Art

[0001] The present disclosure relates to a photoresist composition and a metallization method. In particular, the present disclosure relates to a photoresist composition that prevents the formation of a footprint profile in a photoresist pattern.

[0002] Over the years, mobile devices, devices that are part of the Internet of Things (IoT), and wearable electronic devices have become smaller, lighter, and thinner devices, and despite their increasing miniaturization, they use larger amounts of memory and perform more and more computations.

[0003] The manufacturing and packaging of these electronic devices play an important role in size reduction. For example, flip chip packaging methods have been used to increase the density of I / O (input / output) connections between devices, especially for micro-machined units (MPUs) and dynamic random access memory (DRAM) semiconductor chips.

[0004] Metal pillar bumps, such as copper pillar bumps, are often used as flip-chip interconnects for electronic and optoelectronic packaging, including flip-chip packaging of CPU and GPU integrated circuits (chips), laser diodes, and semiconductor optical amplifiers (SOAs). Metal pillar bumps provide beneficial connection resistance, high-density connections, metal migration resistance, and heat dissipation characteristics. Metal line patterns can also be used, for example, in redistribution layers (RDLs) to provide electrical connections between two components.

[0005] Electroplating has been used to make metal stud bump arrays and line patterns. A photoresist layer is coated on the copper film surface, and then a mask pattern is made using photolithography. Metal structures are then formed on the metal surface by electroplating in the open areas of the mask pattern. The photoresist is then removed and the metal layer previously covered by the resist is removed by etching.

[0006] A method for preparing the plating mask pattern is to use a thick photoresist layer, in response to the thicker and narrower pattern size required for further increasing I / O and device density. Chemically amplified photoresists may be a suitable choice for achieving faster sensitivity and improved transparency required for higher resolution patterns. Such resist compositions include polymers with acid-labile groups, photoacid generators (PAGs) and solvents. However, when chemically amplified resists are formed on metal layers such as copper layers, footprint profile problems caused by the loss of photoacids present at the interface of the metal surface and the resist have been observed.

[0007] The footprint in the resist pattern results in an undercut profile in the plated pattern. This can promote collapse of the plated pattern during downstream processing. Therefore, it is desirable to eliminate the footprint of the photoresist pattern used as a plating mask. Summary of the invention

[0008] Disclosed herein is a photoresist composition comprising a polymer comprising a first repeating unit having formula (3) and a second repeating unit having formula (4): wherein: R1 is a hydrogen atom or a substituted or unsubstituted C1-C3 alkyl group; Z is a non-hydrogen substituent containing an acid-labile moiety; wherein m and n are the number of repeating units of the first repeating unit and the second repeating unit, respectively; a compound having formula (5): (5), wherein: R2 is independently C1-C3 alkyl or C1-C3 alkoxy; and p is an integer from 0 to 4; a photoacid generator; and a solvent.

[0009] Also disclosed herein is a photoresist composition comprising: (a) a polymer; (b) one or more photoacid generators; (c) a first base quencher; (d) a second base quencher; and (e) a solvent; wherein the polymer comprises the following two repeating units: wherein: R1 is a hydrogen atom or a substituted or unsubstituted C1-C3 alkyl group; Z is a non-hydrogen substituent providing an acid-labile moiety; based on the total polymerized units present in the polymer, m is 20 to 90 mol% and n is 10 to 80 mol%; wherein the photoacid generator is selected from N-hydroxynaphthalene dicarboxylic acid imide trifluoromethanesulfonate, N-hydroxynaphthalene dicarboxylic acid imide perfluoro-1-butanesulfonate, N-hydroxynaphthalene dicarboxylic acid imide camphor-10-sulfonate, N-hydroxynaphthalene dicarboxylic acid imide 2-trifluoromethylphenylsulfonate, N-hydroxy-5-norbornene-2,3-dicarboxylic acid imide perfluoro -1-butanesulfonate, N-(trifluoromethanesulfonyloxy)phthalimide and N-hydroxysuccinimide perfluorobutanesulfonate; wherein the first base quencher is selected from N-diethyl dodecylamide, 2,8-dimethyl-6H,12H-5,11-methylenedibenzo[b,f][1,5]diazocine (trogol base), 4-hydroxypiperidine-1-carboxylic acid-1,1-dimethylethyl ester, N-allyl caprolactam, ethyl-3-(morpholino) propionate, 4-(p-tolyl)morpholine, or a combination thereof; wherein the second base quencher is a compound having formula (5): wherein: R2 is independently a C1-C3 alkyl group or a C1-C3 alkoxy group; and p is an integer from 0 to 4; and wherein the solid content of the photoresist composition is from 10 wt % to 60 wt %.

[0010] Also disclosed herein is a method comprising forming a photoresist layer on a metal layer, wherein the photoresist layer comprises: (a) a polymer, (b) a photoacid generator, (c) a first base quencher, and (d) a second base quencher; exposing the photoresist layer to activating radiation in a patterned manner; and contacting the photoresist layer with an alkaline developer to remove the exposed portions of the photoresist layer; and immersing the metal layer in a metal plating solution and depositing metal on the metal layer in the exposed portions of the photoresist layer; wherein the polymer comprises the following two repeating units: wherein: R1 is a hydrogen atom or a substituted or unsubstituted C1-C3 alkyl group; Z is a non-hydrogen substituent that provides an acid-labile moiety; m is 20 to 90 mol% and n is 10 to 80 mol% based on the total polymerized units present in the polymer; and the first base quencher is selected from N-diethyl dodecylamide, 2,8-dimethyl-6H,12H-5,11-methylenedibenzo[b,f][1,5]diazocine (trogol base), 4-hydroxypiperidine-1-carboxylic acid-1,1-dimethylethyl ester, N-allyl caprolactam, ethyl-3-(morpholino)propionate, 4-(p-tolyl)morpholine, or a combination thereof; and the second base quencher is a compound having formula (5): wherein: R2 is independently C1-C3 alkyl or C1-C3 alkoxy; and p is an integer from 0 to 4. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1A An exemplary embodiment of a substrate having a first metal layer disposed thereon is depicted;

[0012] Figure 1B depicts exemplary embodiments of deposition of a photoresist layer on a first metal layer and photopatterning of the photoresist layer and the first metal layer;

[0013] Figure 1C An exemplary embodiment of development of a photoresist layer is depicted;

[0014] Figure 1D is an exemplary depiction of the deposition of metal on a metal layer (by plating);

[0015] Figure 1E depicts the plated metal structure remaining after removal of the remaining photoresist layer;

[0016] Figure 2 depicts Table 1 including data from the working examples;

[0017] Figure 3depicts Table 3 including data from the working examples;

[0018] Figure 4 is a graph of optimum exposure energy for nominal pattern size (Eop) of photoresist compositions versus molar ratio of second base quencher to PAG contained in each composition;

[0019] Figure 5 is a depiction of the weight loss of each of the second base quenchers as determined using thermogravimetric analysis; and

[0020] Figure 6 Table 5 is depicted which includes data from the working examples. DETAILED DESCRIPTION

[0021] As used herein, the terms "a / an" and "the" do not indicate a limitation of quantity and are interpreted to include both the singular and the plural unless otherwise indicated herein or clearly contradicted by the context. Unless explicitly stated otherwise, "or" means "and / or".

[0022] As used herein, "acid-labile groups" refer to groups in which the bonds in the groups are cleaved by the catalytic action of an acid (optionally and typically with a heat treatment), resulting in the formation of polar groups (such as carboxylic acid or alcohol groups) on the polymer, and the portion of the bond that is optionally and typically connected to the cleaved bond is disconnected from the polymer. Such an acid is typically a photogenerated acid in which bond cleavage occurs during post-exposure baking. Suitable acid-labile groups include, for example, tertiary alkyl ester groups, secondary or tertiary aryl ester groups, secondary or tertiary ester groups with a combination of alkyl and aryl groups, tertiary alkoxy groups, acetal groups or ketal groups. Acid-labile groups are also commonly referred to in the art as "acid-cleavable groups", "acid-cleavable protecting groups", "acid-labile protecting groups", "acid leaving groups", "acid-decomposable groups" and "acid-sensitive groups".

[0023] Disclosed herein is a photoresist composition that reduces footprints in a photoresist layer when used as a plating mask. The photoresist composition comprises a polymer containing an acid-labile group; a first base quencher; a second base quencher; and a photoacid generator. Also disclosed herein is a method for manufacturing a semiconductor that minimizes the occurrence of footprints in a photoresist layer during a manufacturing process. Footprints can result in undercutting of a plated pattern, which can promote collapse of the plated pattern during further processing and reliability testing. It is therefore desirable to eliminate or minimize the footprint of a plated pattern.

[0024] The above-mentioned photoresist composition is disposed on a substrate to form a photoresist layer. The photoresist layer is exposed to activating radiation in a patterned manner. The exposed photoresist layer is then developed with an alkaline developer to remove portions of the photoresist layer to form a relief pattern. After the relief pattern is formed, a metal can be plated on the first surface of the substrate.

[0025] Figure 1A-1E A method of forming a plated pattern on a substrate is described. Figure 1A A substrate 100 is depicted with a first metal layer 102 disposed thereon. Figure 1B Depicted is the coating of a photoresist layer 106 on the metal layer 102, and the subsequent photoexposure of the photoresist layer 106. The photoresist layer 106 includes a photoacid generator and a polymer containing acid-labile groups. After coating the photoresist layer 106, the photoresist layer 106 is pattern-wise exposed to activating radiation 108 through a photomask 110 having optically opaque areas and optically transparent areas. UV light having a wavelength of 10 nanometers to 400 nanometers can be used in photopatterning.

[0026] Figure 1C The development of the exposed portions of the photoresist layer 106 is depicted. The exposed portions of the photoresist layer 106 are removed by development, such as from Figure 1C As can be seen in Figure 1D After metal plating, visible in FIG. 1 , the remaining portions of the photoresist layer may be removed (stripped) from the substrate to leave the plated metal structures 112 . Figure 1E Depicted is the plated metal structure 112 that remains after removal of the remaining photoresist layer.

[0027] The various layers described above (depicted in FIG. Figure 1A-1E in) and their respective compositions. Base

[0028] Examples of substrates include, but are not limited to, silicon wafers, glass substrates, and plastic substrates, such substrates optionally including one or more layers or features formed thereon. A preferred substrate is a silicon wafer. Metal layer

[0029] Figure 1AA substrate 100 is depicted with a first metal layer 102 disposed thereon. An optional second metal layer (not shown) may be disposed on the first metal layer 102. The first metal layer may be composed of, for example, titanium, silver, aluminum, gold, copper, or an alloy thereof. In an exemplary embodiment, the first metal layer 102 comprises titanium or copper. When the second metal layer is disposed on the first metal layer, the first metal layer preferably comprises titanium. The metal first layer may be formed using known methods, such as by chemical vapor deposition (CVD), plasma enhanced chemical vapor deposition (PECVD), or physical vapor deposition (PVD) techniques, wherein sputtering and plating are typical. The thickness of the first metal layer 102 is typically 10 nm to 500 nm.

[0030] The optional second metal layer includes tantalum, titanium, copper, silver, aluminum, gold or an alloy thereof. The second metal layer is chemically different from the first metal layer 102. In an exemplary embodiment, the second metal layer includes copper. The second metal layer can be disposed on the surface of the first metal layer via chemical vapor deposition (CVD), plasma enhanced chemical vapor deposition (PECVD), physical vapor deposition (PVD) or a combination thereof. The thickness of the second metal layer is typically 10nm to 500nm. Photoresist layer

[0031] Figure 1B Deposition of a photoresist layer 106 on the first metal layer 102 is depicted. The photoresist composition 106 comprises a polymer comprising an acid-labile group; a photoacid generator; a first base quencher and a second base quencher. The polymer comprises a first repeating unit comprising an acid-labile group. In an embodiment, the polymer comprises a second repeating unit comprising a vinyl aromatic group.

[0032] Acid labile groups are chemical moieties that undergo deprotection reactions in the presence of acid. The deprotection of some acid labile groups used in the examples is caused by heat. Acetal protecting groups are easily deprotected at room temperature. The solubility of the polymer of the photoresist composition in the developer changes, which is the result of the acid reaction with the photoacid generator (contained in the photoresist composition) after soft baking, exposure to activating radiation and post-exposure baking. This is due to the cleavage of the acid labile groups induced by the photoacid causing the polarity of the polymer to change. The acid labile group can be selected from, for example, tertiary alkyl carbonates, tertiary alkyl esters, tertiary alkyl ethers, acetals and ketals. Preferably, the acid labile group is an ester group containing a tertiary non-cyclic alkyl carbon or a tertiary alicyclic carbon covalently linked to the carboxyl oxygen of the ester of the polymer. The cleavage of such acid labile groups results in the formation of a carboxylic acid group.

[0033] In one embodiment, the polymer containing an acid-labile group comprises a polymerized unit having a structure represented by the following formula (1): wherein Z is selected from a hydrogen atom, a substituted or unsubstituted C1-C4 alkyl group, a substituted or unsubstituted C1-C4 fluoroalkyl group or a cyano group; 1 is a non-hydrogen substituent containing an acid labile group which upon cleavage forms a carboxylic acid on the polymer.

[0034] In an embodiment, the acid labile group that decomposes to form a carboxylic acid group on the polymer is preferably a group having the formula -C(O)OC(R 1 )3 or a tertiary ester group having the formula -C(O)OC(R 2 )2OR 3 An acetal group, wherein: R 1 Each independently is a straight chain C 1-20 Alkyl, branched chain C 3-20 Alkyl, monocyclic or polycyclic C 3-20 Cycloalkyl, straight chain C 2-20 Alkenyl, branched C 3-20 Alkenyl, monocyclic or polycyclic C 3-20 Cycloalkenyl, monocyclic or polycyclic C 6-20 Aryl, or monocyclic or polycyclic C 2-20 Heteroaryl, preferably straight chain C 1-6 Alkyl, branched chain C 3-6 Alkyl, or monocyclic or polycyclic C 3-10 Cycloalkyl, each of which is substituted or unsubstituted, each R 1 It may optionally include one or more groups selected from -O-, -C(O)-, -C(O)-O- or -S- as part of its structure, and any two R 1 The groups together optionally form a ring; R 2 are independently hydrogen, fluorine, straight chain C 1-20 Alkyl, branched chain C 3-20 Alkyl, monocyclic or polycyclic C 3-20 Cycloalkyl, straight chain C 2-20 Alkenyl, branched C 3-20 Alkenyl, monocyclic or polycyclic C 3-20 Cycloalkenyl, monocyclic or polycyclic C 6-20 Aryl, or monocyclic or polycyclic C 2-20 Heteroaryl, preferably hydrogen, straight chain C 1-6 Alkyl, branched chain C 3-6 Alkyl, or monocyclic or polycyclic C 3-10 Cycloalkyl, each of which is substituted or unsubstituted, each R 2 optionally includes one or more groups selected from -O-, -C(O)-, -C(O)-O- or -S- as part of its structure, and R 2 The groups together optionally form a ring; and R 3 It is a straight chain C1-20 Alkyl, branched chain C 3-20 Alkyl, monocyclic or polycyclic C 3-20 Cycloalkyl, straight chain C 2-20 Alkenyl, branched C 3-20 Alkenyl, monocyclic or polycyclic C 3-20 Cycloalkenyl, monocyclic or polycyclic C 6-20 Aryl, or monocyclic or polycyclic C 2-20 Heteroaryl, preferably straight chain C 1-6 Alkyl, branched chain C 3-6 Alkyl, or monocyclic or polycyclic C 3-10 Cycloalkyl, each of which is substituted or unsubstituted, R 3 It may include one or more groups selected from -O-, -C(O)-, -C(O)-O- or -S- as part of its structure, and one R 2 With R 3 Together they optionally form a ring. Such monomers are typically vinyl aromatic compounds, (meth)acrylates or norbornyl monomers.

[0035] Suitable acid-labile group-containing units include, for example, acid-labile (alkyl)acrylate units, such as tert-butyl (meth)acrylate, 1-methylcyclopentyl (meth)acrylate, 1-ethylcyclopentyl (meth)acrylate, 1-isopropylcyclopentyl (meth)acrylate, 1-propylcyclopentyl (meth)acrylate, 1-methylcyclohexyl (meth)acrylate, 1-ethylcyclohexyl (meth)acrylate, 1-isopropylcyclohexyl (meth)acrylate, 1-propylcyclohexyl (meth)acrylate, methyladamantyl (meth)acrylate, ethyladamantyl (meth)acrylate, and the like, as well as other cyclic and non-cyclic (alkyl)acrylates including alicyclic ones.

[0036] Acetal and ketal acid labile groups can be replaced by alkali soluble groups such as the hydrogen atom at the end of the carboxyl group, thereby bonding with oxygen atoms. When acid is produced, the acid makes the bond cracking between the oxygen atom to which the group that inhibits dissolution of acetal or ketal groups and acetal-type acids can be dissociated. Exemplary such acid labile groups are described in, for example, U.S. Patent Nos. US6057083, US 6136501 and US 8206886, and European Patent Publication Nos. EP 01008913 A1 and EP 00930542A1. Equally suitable are acetal and ketal groups (its cracking will cause the formation of hydroxyl groups) as a part of sugar-derived structures, such as those described in U.S. Patent Application No. US2012 / 0064456 A1.

[0037] Suitable polymers include, for example, phenolic resins containing acid-labile groups. Particularly preferred resins of this type include: (i) polymers containing polymerized units of vinylphenol and acid-labile (alkyl) acrylates as described above, such as polymers described in U.S. Pat. Nos. 6,042,997 and 5,492,793; (ii) polymers containing polymerized units of vinylphenol, optionally substituted vinylphenyl (e.g., styrene) without hydroxyl or carboxyl ring substituents, and acid-labile (alkyl) acrylates as described above, such as polymers described in U.S. Pat. No. 6,042,997; (iii) polymers containing repeating units comprising acetal or ketal moieties that will react with photoacids and optionally aromatic repeating units (e.g., phenyl or phenolic groups); such polymers are described in U.S. Pat. Nos. 5,929,176 and 6,090,526; and blends of (i) and / or (ii) and / or (iii). Such polymers can be used for imaging at wavelengths of, for example, 200 nm or greater (e.g., 248 nm and 365 nm).

[0038] Suitable polymers include those useful for imaging at certain wavelengths below 200 nm, such as 193 nm, such as those disclosed in European Patent Publication No. EP 930542A1 and U.S. Pat. Nos. 6,692,888 and 6,680, 159. For imaging at 193 nm, the polymer is preferably substantially free (e.g., less than 15 mole %), preferably completely free of phenyl, benzyl or other aromatic groups, where such groups are highly radiation absorbing.

[0039] Other suitable polymers for use in photoresist compositions include, for example, those containing polymerized units of non-aromatic cyclic olefins (endocyclic double bonds) such as optionally substituted norbornenes, such as those described in U.S. Pat. Nos. 5,843,624 and 6,048,664. Still other suitable polymers for use in photoresist compositions include polymers containing polymerized anhydride units, particularly polymerized maleic anhydride units and / or itaconic anhydride units, such as disclosed in European Published Application EP 01008913A1 and U.S. Pat. No. 6,048,662.

[0040] Also suitable for use in the photoresist composition are polymers containing repeating units containing heteroatoms, particularly oxygen and / or sulfur (but not anhydrides, i.e., the units do not contain keto ring atoms). The heteroalicyclic units may be fused to the polymer backbone and may include fused carbon alicyclic units (such as provided by polymerization of norbornene groups) and / or anhydride units (such as provided by polymerization of maleic anhydride or itaconic anhydride). Such polymers are disclosed in International Publication No. WO0186353 A1 and U.S. Pat. No. 6,306,554. Other suitable polymers containing heteroatom groups include polymers containing polymerized carbocyclic aromatic units (e.g., hydroxynaphthyl) substituted with one or more groups containing heteroatoms (e.g., oxygen or sulfur), as disclosed in U.S. Pat. No. 7,244,542.

[0041] The polymer may further comprise a unit containing a lactone moiety for controlling the dissolution rate of the polymer and the photoresist composition. Suitable monomers for polymers containing lactone moieties include, for example, the following:

[0042] In an embodiment, the polymer further typically comprises a unit containing a polar group, which enhances the etch resistance of the polymer and the photoresist composition and provides an additional means of controlling the dissolution rate of the polymer and the photoresist composition. Monomers used to form such units include, for example, the following:

[0043] The polymer may contain one or more additional units of the above type. Typically, the additional units used in the polymer will contain polymerizable groups that are the same or similar to the polymerizable groups used in the monomers used to form the other units of the polymer, but may contain other different polymerizable groups in the same polymer backbone.

[0044] The polymer may also include one or more repeating units derived from the polymerization of a vinyl aromatic monomer. An exemplary vinyl aromatic monomer is styrene. In an embodiment, the polymer derived from a vinyl aromatic monomer has a structure shown in the following formula (2): Where a is 1 to 5 and where Z 2 is hydrogen or an alkyl group having 1 to 5 carbon atoms. In a preferred embodiment, a is 1 and Z 2 is hydrogen. Preferably, the vinyl aromatic monomer has a hydroxyl group located in the para position on the aromatic ring. A preferred vinyl aromatic polymer is poly(p-hydroxystyrene) (abbreviated as PHS).

[0045] In an embodiment, the polymer for the photoresist composition comprises a first repeating unit having formula (3) and a second repeating unit having formula (4): Wherein: R1 is a hydrogen atom or a substituted or unsubstituted C1-C3 alkyl group; Z is a non-hydrogen substituent containing an acid-labile moiety. In an embodiment, m+n (in formula (3) and (4)) is 70 to 100 mole percent (mol%). In an embodiment, based on the total polymerized units present in the polymer, m is 10 to 90 mol%, preferably 25 to 80 mol%, preferably 30 to 40 mol%, and n is 10 to 90 mol%, preferably 20 to 70 mol%. In an embodiment, the molar ratio of n to m is 0.11 to 9, preferably 0.2 to 4.

[0046] When the polymer comprises a third repeating unit (different from the first repeating unit and the second repeating unit), the third repeating unit may be present in the polymer in an amount of 5 to 35 mol %, preferably 10 to 30 mol %, based on the total polymerized units present in the polymer.

[0047] Although not limited thereto, exemplary polymers include, for example, the following:

[0048] Suitable polymers for use in photoresist compositions are commercially available and can be readily prepared by one skilled in the art.The polymer is present in the photoresist composition in an amount sufficient to render the exposed coating of the photoresist developable in a suitable developer solution.

[0049] Typically, the polymer is present in the photoresist composition in an amount of 70 wt % to 100 wt % based on the total solids of the photoresist composition. The weight average molecular weight M of the polymer is w Typically less than 100,000, for example 4000 to 100,000, more typically 4000 to 20,000 grams per mole (g / mol) as measured by gel permeation chromatography using a polystyrene standard. Blends of two or more of the above described polymers may suitably be used in the photoresist compositions of the present invention.

[0050] The photoresist composition comprises a non-ionic photoacid generator. In an embodiment, the photoresist composition may optionally contain an ionic photoacid generator. It is desirable to use a photoacid generator that generates photoacid by Norrish-1 cleavage. The Norrish-I reaction is the photochemical cleavage or homolysis of aldehydes and ketones into two free radical intermediates. The carbonyl group receives a photon and is excited to a photochemical singlet state. In an embodiment, the photoacid generator has the structure shown in formula (5): In formula (4), R4 is a hydrogen atom, a substituted or unsubstituted straight or branched C1 to C 14 An alkyl group, a substituted heterocyclic group, or a halogen atom; and wherein R5 is a substituted or unsubstituted alkyl group having 1 to 18 carbon atoms; a halogen atom, or an aryl group having 6 to 20 unsubstituted carbon atoms.

[0051] Examples of suitable photoacid generators are N-hydroxynaphthalene dicarboxylic acid imide trifluoromethanesulfonate (NHNI-TF), N-hydroxynaphthalene dicarboxylic acid imide perfluoro-1-butanesulfonate (NHNI-PFBS), N-hydroxynaphthalene dicarboxylic acid imide camphor-10-sulfonate, N-hydroxynaphthalene dicarboxylic acid imide 2-trifluoromethylbenzenesulfonate, N-hydroxy-5-norbornene-2,3-dicarboxylic acid imide perfluoro-1-butanesulfonate, N-(trifluoromethylsulfonyloxy)phthalimide, N-hydroxysuccinimide perfluorobutanesulfonate or benzyl cyanide, 2-methyl-α-[2-[[(propylsulfonyl)oxy]imino]-3(2H)-thienyl]-(commercially available as IRGACURE PAG 103). In a preferred embodiment, the photoacid generator may be one or more of the structures of formula (5a) or (5b) shown below:

[0052] The photoacid generator is present in the photoresist composition in an amount of 0.2 to 15 wt %, more typically 0.3 to 5 wt %, and more preferably 0.5 to 2 wt % based on the total solids of the photoresist composition.

[0053] As described above, the photoresist composition comprises a first base quencher and a second base quencher. The base quencher improves the resolution of the developed resist relief image. The first base quencher is preferably a base weaker than a common tertiary amine. The lower basicity prevents the decomposition of the i-line sensitive photoacid generator during the storage of the photoresist composition. The first base quencher is selected from the group consisting of: N-diethyl dodecylamide, 2,8-dimethyl-6H,12H-5,11-methylenedibenzo[b,f][1,5]diazocin (trog base), 4-hydroxypiperidine-1-carboxylic acid-1,1-dimethylethyl ester, N-allyl caprolactam, ethyl-3-(morpholino) propionate, 4-(p-tolyl) morpholine, or a combination thereof.

[0054] The first base quencher is preferably added in an amount effective to impart to the photoresist composition a pKa of less than 7. The amount of the first base quencher in the photoresist layer is preferably 0.001 wt % to 1.0 wt %, more preferably 0.01 wt % to 0.8 wt %, or 0.02 wt % to 0.2 wt %, based on the total weight of solids in the photoresist composition.

[0055] The second base quencher comprises a 2-mercapto aromatic azole analog. In an embodiment, the aromatic azole analog comprises a thiol functional unit in position 2 of the aromatic azole compound. If position 2 is replaced with a chemical moiety other than thiol (such as, for example, a methyl-thio or carboxyl-methyl-thio moiety), it does not improve the footprint profile on the copper substrate.

[0056] Examples of aromatic azole analogs include benzoxazole. Examples of benzoxazoles that can be used as the second base quencher include compounds having formula (6): wherein: R2 is independently a C1-C3 alkyl group or a C1-C3 alkoxy group; and p is an integer from 0 to 4. The amount of the second base quencher is 0.01 wt% to 1 wt% based on the total weight of solids in the photoresist composition. When viewed in cross section, a second base quencher load in an amount greater than 1 wt% (exceeding the load formed by the chemical adsorption layer) may affect the angled pattern profile.

[0057] The photoresist composition further comprises a solvent. The solvent is used to solvate the polymer used in the composition and to promote the miscibility of various ingredients used in the composition.

[0058] Solvents generally suitable for dissolving, dispensing and coating include anisole, alcohols (including 1-methoxy-2-propanol (also known as propylene glycol methyl ether, PGME) and 1-ethoxy-2-propanol), esters (including n-butyl acetate, 1-methoxy-2-propyl acetate (also known as propylene glycol methyl ether acetate, PGMEA), methoxyethyl propionate, ethoxyethyl propionate), ketones (including cyclohexanone, 2,6-dimethyl-4-heptanone, 2-heptanone); ethyl lactate (EL), methyl 2-hydroxyisobutyrate (HBM), γ-butyrolactone (GBL), methyl 3-methoxypropionate, and combinations thereof.

[0059] The amount of solvent can be, for example, 25 wt% to 1900 wt%, preferably 67 wt% to 900 wt%, and more preferably 100 wt% to 150 wt%, based on the total weight of the solids of the photoresist composition. It should be understood that the "polymer" used in the context of the components in the photoresist layer can only mean the polymer disclosed herein (which contains acid-labile groups). It will be understood that the total solids include polymers, photodestructible bases, quenchers, surfactants, photoacid generators, and any optional additives (excluding solvents). The solid content of the composition can be 5 wt% to 80 wt%, preferably 10 wt% to 60 wt%.

[0060] The photoresist composition may contain other optional ingredients, such as one or more surface leveling agents (SLA), adhesion promoters and / or plasticizers. If used, the SLA is preferably present in an amount of 0.001 wt% to 0.1 wt% based on the total weight of the solids of the photoresist composition, and if used, the adhesion promoter and / or plasticizer are each present in an amount of 0.1 wt% to 10 wt% based on the total weight of the solids of the photoresist composition.

[0061] The photoresist composition is applied to the first metal layer 102 to form a photoresist layer 106. In an embodiment, the photoresist layer has a thickness greater than 2 microns. The photoresist composition is usually applied to the surface of the metal layer via spin coating, dipping, roller coating or some other conventional coating techniques. Preferably, spin coating. For spin coating, the solid content of the coating solution can be adjusted based on the specific coating equipment used, the viscosity of the solution, the speed of the coating tool and the time amount allowed to rotate to provide a desired film thickness. In an embodiment, the photoresist composition is applied with a single application.

[0062] The photoresist composition layer is then pattern-wise exposed to activating radiation through a photomask to create a solubility difference between exposed and unexposed areas. Figure 1BAfter the photoresist layer 106 is deposited, a mask 110 is disposed on the photoresist layer 106 to perform photopatterning on the photoresist layer 106. UV light with a wavelength of 10 nanometers to 500 nanometers may be used in the photopatterning. The exposed portion of the photoresist layer may be removed by a suitable alkaline developer, such as from Figure 1C Visible in.

[0063] The exposure of the photoresist composition layer to radiation that has an activating effect on the layer mentioned herein means that the radiation is capable of forming a latent image in the layer. The photomask has optically transparent and optically opaque regions corresponding to the regions to be exposed and unexposed in the resist layer by the activating radiation, respectively. The exposure wavelength is typically below 500 nm, such as UV-visible light of 200 to 500 nm. Preferably, the exposure is carried out with radiation of a 365 nm wavelength (i-line) of a mercury lamp.

[0064] After exposure of the photoresist composition layer, a post-exposure bake (PEB) is typically performed to decompose the acid-labile groups by the acid generated by the PAG during the exposure step. The PEB can be performed, for example, on a hot plate or in an oven. A latent image defined by the boundary between polarity-switched and unswitched regions (corresponding to exposed and unexposed regions, respectively) is thereby formed.

[0065] The photoresist composition layer is then contacted with an alkaline developer solution to remove the exposed portions of the layer, thereby leaving the unexposed areas to form a resist pattern. The developer is typically an aqueous alkaline developer, such as a quaternary ammonium hydroxide solution, for example, a tetraalkylammonium hydroxide solution, such as 0.26 normal (N) (2.38 wt%) tetramethylammonium hydroxide (TMAH).

[0066] A further aspect is a process for depositing metal on the metal layer 102 . Figure 1D 1 is an exemplary depiction of depositing metal (via plating) 112 on metal layer 102. The process includes immersing the metal layer in a metal plating solution and electrodepositing metal on the metal layer in exposed portions of the photoresist composition layer. Metal layer 112 is typically formed on a substrate or on exposed portions of first metal layer 102.

[0067] The substrate with patterned photoresist layer 106 can be immersed in a metal coating solution to plate metal in those areas where the photoresist composition layer has been developed on the exposed first metal layer. The developed area of ​​the photoresist composition layer serves as a mold for metal plating. The metal can be plated, for example, by electroplating. Various types of metal plating solutions known in the art can be used. In addition, two or more different metal layers can be formed, and the layer can be the same or different metal layers. Preferred plated metals include but are not limited to copper, nickel, tin, silver, gold and mixtures thereof and alloys. Suitable metal plating solutions for forming such metals are known in the art and are derived from DuPont Electronics & Industrial. The thickness of the plated metal layer is typically 1 to 100 microns, preferably 5 to 50 microns. The plated metal layer thickness can be less than or exceed the thickness of the photoresist layer.

[0068] After metal plating, the remaining photoresist layer may be removed (stripped) from the substrate to leave the plated metal structure 112 . Figure 1E Depicted is the plated metal structure 112 that remains after removal of the remaining photoresist layer. Suitable photoresist strippers are available from, for example, DuPont Electronic Industries.

[0069] The exposed first metal layer between the plated metal structures can be optionally removed, for example, by an etch-back process, to electrically isolate each of the plated metal structures. The obtained metal structure can have, for example, a line shape, which can be used for a redistribution layer to provide electrical connection between two components. Advantageously, metal lines with small widths and straight (vertical) sidewalls can be formed by the compositions and methods disclosed herein. Such structures are used for electrical connection in, for example, small, light and thin devices. The width of the line can be, for example, 0.8 micron to 100 microns, preferably 1 micron to 50 microns. The height of the line will, for example, depend on the thickness of the photoresist composition resin, but a column height of 2 microns or more can be formed.

[0070] An advantage of the present invention is that a photoresist composition can be used to obtain a line having a larger cross-sectional area at the base than at the top of the pillar. The use of the disclosed photoresist composition prevents the formation of undercuts at the bottom of the metal line. This prevents collapse of the line during further processing of the semiconductor.

[0071] The invention will now be illustrated by the following non-limiting examples. Examples Example 1

[0072] This example was conducted to demonstrate the use of a photoresist composition comprising a first base quencher and a second base quencher, wherein the second base quencher comprises an azole that reduces footprint. Examples were also conducted to determine which specific substituents and the positions of those substituents will have a significant effect on the footprint profile. These examples demonstrate which specific azole analogs can be used to minimize footprint in a photoresist layer.

[0073] The photoresist composition (used in this example) comprises a polymer comprising repeating units having an acid-labile group, repeating units comprising hydroxystyrene, and repeating units comprising styrene, as seen in the following formula (7). The polymer comprises a copolymer of poly(4-hydroxystyrene) in an amount of 70 mol%, polystyrene in an amount of 10 mol%, and poly(tert-butyl acrylate) in an amount of 20 mol%, based on the total polymerized units present in the polymer.

[0074] The weight average molecular weight of the polymer shown in formula (7) was 21,700 g / mole, as determined using styrene standards.

[0075] NHNI-TF (methanesulfonic acid, 1,1,1-trifluoro-, 1,3-dioxo-1H-benzo[de]isoquinolin-2(3H)-yl ester) and NHNI-PFBS (1,3-dioxo-1H-benzo[de]isoquinolin-2(3H)-yl 1,1,2,2,3,3,4,4,4-nonafluorobutane-1-sulfonate) (Toyo Gosei Co.), both of which are shown below as photoacid generators (PAGs) for use. The first base quencher is trogol base (2,8-dimethyl-6H,12H-5,11-methylenedibenzo[b,f][1,5]diazocin) (WAKO Fuji Film Co.). It was diluted to a 1 wt% solution in PGMEA. It was then filtered with a 0.45 μm PTFE filter to remove any insoluble impurities.

[0076] Provides plasticizer LUTONAL TM M40 (polyvinyl ethyl ether) (BASF Japan Co.) and surface leveling agent (SLA) POLYFOX TMPF-656 (OMNOVA Solutions Inc.). PGMEA (propylene glycol monoethyl acetate), PGME (1-methoxy-2-propanol) and γ-butyrolactone were mixed together and used as a solvent in the photoresist composition. These ingredients were placed in a polypropylene bottle and shaken using a roller shaker (Roller Digital 10, Japanese companies( Japan KK)) was stirred at a rotation speed of 10 rpm overnight. After confirming that these components were dissolved, filtration was performed using a 10 μm pore size PTFE membrane filter.

[0077] The composition of each sample is indicated in each section of the corresponding (Formulation) table. The weights of PAG, base quencher and other additives such as SLA, plasticizer, solvent and other ingredients are expressed as parts by weight (pbw) relative to 100 parts of polymer. In addition, the loading level of one or more second base quenchers is also expressed as a molar ratio of PAG.

[0078] A 150 nm thick titanium layer was deposited on a 150 mm silicon substrate. A 200 nm thick copper layer was then deposited on the titanium layer by sputtering. The surface of the copper layer was washed with a 10 wt % sulfuric acid (H2SO4) solution for 30 seconds to remove the surface oxide layer, followed by a rinse with deionized (DI) water. The water was then removed by blowing a pressurized nitrogen stream onto the substrate. The substrate was puddle coated with a 2.38 wt % TMAH solution for 60 seconds, followed by a rinse with deionized water. The substrate was then spin dried.

[0079] The photoresist composition was then spin coated on the copper layer using a Sokudo D-Spin 60A SK-W60A-AVP wafer track. After soft baking at 135° C. for 6 minutes, the spin speed was adjusted to obtain a 50 micrometer (μm) thick photoresist layer.

[0080] The photoresist layer was then subjected to broadband UV exposure using a multi-tone exposure mask with square contact hole patterns of various sizes on a Dainippon Kaken MA-1200 proximity mask aligner. A post-exposure bake (PEB) was performed at 90°C for 3 minutes.

[0081] Then 2.38 wt% TMAH aqueous developer ( The exposed photoresist layer was subjected to puddle development 4 times for 60 seconds each time using CD-26, DuPont Electronic Industries, Inc. After development, the substrate was then rinsed with water and spin dried.

[0082] The contact hole width was measured from top view images taken using an optical microscope (H300, Lasertec, using LIBRA software). Cross-sectional images of the contact holes were obtained using a scanning electron microscope to determine the amount of footprint present. Images were captured at a magnification of 50x. Example 2

[0083] Figure 2 The solubility of the compounds shown in Table 1 was determined by the human eye using a 1 wt% solution in PGMEA. The pKa values ​​were taken from SciFinder n+.

[0084] Table 2 shows different formulations of photoresist compositions that were evaluated to determine which second base quenchers showed useful sensitivity. All samples in Table 2 used Trog base as the first base quencher. As can be seen from Table 2 below, samples 1 to 3 used 2-mercapto 5-methoxybenzothiazole (MBT) as the second base quencher, while samples 4-6 used 2-mercaptobenzoxazole (MBO) as the second base quencher. Samples 7-9 used benzotriazole as a quencher. The molar ratio of the second base quencher to the PAG varied from 0.09 to 0.21 to 0.33. Two PAGs were used, notably NHNI-PFBS and NHNI-TF, in amounts of 0.41 and 0.29 parts by weight per 100 parts by weight of the polymer. Samples 1-3 and 7-9 are comparative examples, while samples 4 to 6 illustrate the present invention. Table 2 Comp = Comparative Example

[0085] The formulations of Table 2 are used in photoresist compositions to determine which second base quencher produces the best sensitivity in the photoresist composition. When ratioed to the total molar PAG loading in the photoresist composition, the molar loading levels of the second base quencher in the corresponding photoresist composition are adjusted to be equal to each other. Sensitivity is defined as the exposure energy that gives an equivalent pattern size (or hole width) for each photoresist composition. When compared with a photoresist composition using a larger amount of exposure energy, a smaller number (amount) of exposure energy (i.e., a lower exposure energy for producing an equivalent pattern size) indicates that the sensitivity of the photoresist composition is greater. A more sensitive photoresist composition (a photoresist composition using less exposure energy) is better for energy consumption and productivity. Figure 3Table 3 in Figure 3 shows the sensitivity of three different photoresist compositions (containing 2-mercapto 5-methoxybenzothiazole (MBT), benzotriazole (BTA) or 2-mercaptobenzoxazole (MBO)) when used to produce 25 micron holes. When used in a photoresist composition, 2-mercaptobenzoxazole (MBO) shows the lowest energy exposure (and therefore the best sensitivity) of the three compounds.

[0086] Figure 4 is a graph depicting the exposure energy (E op ) versus the molar ratio (of the second base quencher to the PAG) contained in each composition. Figure 4 yes Figure 3 The exposure energy (E) for producing a 25 μm hole is shown in FIG. op ). Thus, this graph reflects the sensitivity of the photoresist compositions. 2-Mercaptobenzoxazole (MBO) shows the lowest energy exposure (and therefore the best sensitivity) of the three second base quencher compounds when used in a photoresist composition.

[0087] Figure 5 is a depiction of the weight loss of each of the second base quenchers over a temperature range of 50°C to the corresponding thermal degradation temperature as determined using thermogravimetric analysis. Figure 5 It can be seen that 2-mercaptobenzoxazole (MBO) shows better thermal stability than BTA or MBT. Example 3

[0088] This example was conducted to determine the effect of varying the ratio of the first base quencher to the second base quencher in a photoresist composition.

[0089] The amount of the first base quencher (Trog base) was increased relative to the second base quencher (2-mercaptobenzoxazole) to evaluate its effect on the pattern profile (see Table 4). The loading of the second base quencher (2-mercaptobenzoxazole) showing the copper passivation effect was fixed at 0.053 pbw relative to 100 parts by weight of the polymer. The first base quencher varied from 0.038 pbw to 0.050 pbw to 0.063 pbw. The cross-sectional pattern profiles of the 25, 20 and 15 μm contact hole patterns were formed at exposure energies to achieve a nominal size (Eop) of 25 μm. Table 4

[0090] As from Figure 6 As can be seen in Table 5, all samples exhibit a narrow footprint regardless of the sidewall angle.

Claims

1. A photoresist composition comprising: A polymer comprising a first repeating unit having formula (3) and a second repeating unit having formula (4): (3) (4)， in: R1 is a hydrogen atom or a substituted or unsubstituted C1-C3 alkyl group; Z is a non-hydrogen substituent containing an acid-labile moiety; A compound having formula (6): Wherein: R2 is independently C1-C3 alkyl or C1-C3 alkoxy; and p is an integer from 0 to 4; photoacid generators; and Solvent.

2. The photoresist composition of claim 1, further comprising a base quencher different from the compound of formula (6).

3. The photoresist composition according to claim 2, wherein The base quencher is selected from N-diethyl dodecanamide, 2,8-dimethyl-6H,12H-5,11-methylenedibenzo[b,f][1,5]diazocine (trogol base), 4-hydroxypiperidine-1-carboxylic acid-1,1-dimethylethyl ester, N-allyl caprolactam, ethyl-3-(morpholino) propionate, 4-(p-tolyl)morpholine, or a combination thereof.

4. The photoresist composition according to claim 2 or 3, wherein The molar ratio of the base quencher to the compound of formula (6) is 0.01:1 to 0.5:

1.

5. A photoresist composition as claimed in any one of the preceding claims, wherein The photoacid generator is selected from N-hydroxynaphthalene dicarboxylic acid imide trifluoromethanesulfonate, N-hydroxynaphthalene dicarboxylic acid imide perfluoro-1-butanesulfonate, N-hydroxynaphthalene dicarboxylic acid imide camphor-10-sulfonate, N-hydroxynaphthalene dicarboxylic acid imide 2-trifluoromethylphenylsulfonate, N-hydroxy-5-norbornene-2,3-dicarboxylic acid imide perfluoro-1-butanesulfonate, N-(trifluoromethanesulfonyloxy)phthalimide and N-hydroxysuccinimide perfluorobutanesulfonate.

6. A photoresist composition as claimed in any one of the preceding claims, wherein The molar ratio of the compound having formula (6) to the photoacid generator is 0.01:1 to 0.5:

1.

7. A photoresist composition as claimed in any one of the preceding claims, wherein The compound having formula (6) is 2-mercaptobenzoxazole.

8. A photoresist composition comprising: (a) a polymer; (b) one or more photoacid generators; (c) a base quencher; (d) a mercaptobenzoxazole compound; and (e) a solvent; The polymer comprises the following two repeating units: wherein R1 is a hydrogen atom or a substituted or unsubstituted C1-C3 alkyl group; Z is a non-hydrogen substituent that provides an acid-labile moiety; wherein the photoacid generator is selected from N-hydroxynaphthalene dicarboxylic acid imide trifluoromethanesulfonate, N-hydroxynaphthalene dicarboxylic acid imide perfluoro-1-butanesulfonate, N-hydroxynaphthalene dicarboxylic acid imide camphor-10-sulfonate, N-hydroxynaphthalene dicarboxylic acid imide 2-trifluoromethylphenylsulfonate, N-hydroxy-5-norbornene-2,3-dicarboxylic acid imide perfluoro-1-butanesulfonate, N-(trifluoromethanesulfonyloxy)phthalimide and N-hydroxysuccinimide perfluorobutanesulfonate; wherein the base quencher is selected from N-diethyl dodecanamide, 2,8-dimethyl-6H,12H-5,11-methylenedibenzo[b,f][1,5]diazocine (trogol base), 4-hydroxypiperidine-1-carboxylic acid-1,1-dimethylethyl ester, N-allyl caprolactam, ethyl-3-(morpholino) propionate, 4-(p-tolyl)morpholine, or a combination thereof; The mercaptobenzoxazole compound has the formula (6): in: R2 is independently C1-C3 alkyl or C1-C3 alkoxy; and p is an integer from 0 to 4; and The solid content of the photoresist composition is 10 wt % to 60 wt %.

9. The photoresist composition according to claim 8, wherein The second base quencher is 2-mercaptobenzoxazole.

10. A method comprising: (i) providing a substrate, the substrate comprising a metal layer on a surface of the substrate; (ii) forming a photoresist layer on the metal layer, wherein the photoresist layer is formed from the photoresist composition according to any one of claims 1 to 9; (iii) pattern-wise exposing the photoresist layer to activating radiation; as well as (iv) contacting the photoresist layer with an alkaline developer to remove the exposed portions of the photoresist layer; as well as (v) immersing the substrate in a metal plating solution and depositing metal in the exposed portions of the photoresist layer on the metal layer.

Images