Photoresist, process for producing a silicic acid (hetero)poly(co)condensate with positive resist behavior and silicic acid (hetero)poly(co)condensate

Abstract

Photoresist with positive resist behavior, consisting of a) a silicic acid (hetero)poly(co)condensate with positive resist behavior, preparable from a silane according to the general formula I [P-(Y 1 ) c -X-(Y 2 ) c ] a Si(R 1 ) b (R 2 ) 4-a-b Formula 1 where P is a photolabilizable group and is selected from the group consisting of radicals of the general formula IV where R 3is selected from the group consisting of linear or branched alkyl radicals having 1 to 18 carbon atoms, preferably tertiary alkyl groups, such as t-butyl, 1-ethylnorbornyl, 1-methylcyclohexyl, 1-ethylcyclopentyl, 2-(2-ethyl)adamantyl or t-amyl groups; trialkylsilyl groups, such as trimethylsilyl, triethylsilyl or dimethyl-tert-butylsilyl groups; ester groups, such as t-butoxycarbonyloxy (t-BOC) or oxoalkyl groups (e.g. 3-oxocyclohexyl group), X represents the grouping shown below: where Z is selected from the group consisting of S, O, NR 4 , C(R 4 )2, R 4 is the same or different at each occurrence and is selected from the group consisting of hydrogen and linear or branched alkyl radicals having 1 to 18 carbon atoms, cycloaliphatic groups having 6 to 24 carbon atoms or aromatic groups having 6 to 24 carbon atoms and n is 1, Y 1 and Y 2 are the same or different at each occurrence and are selected from the group consisting of saturated or unsaturated alkylene groups having 1 to 18 carbon atoms, cycloaliphatic groups having 6 to 24 carbon atoms or aromatic groups having 6 to 24 carbon atoms, R 1 is selected from the group consisting of linear or branched alkyl radicals having 1 to 18 carbon atoms, cycloaliphatic groups having 6 to 24 carbon atoms or aromatic groups having 6 to 24 carbon atoms, R 2 a group -OR 3 where R 3 is selected from the group consisting of linear or branched alkyl radicals having 1 to 18 carbon atoms, cycloaliphatic groups having 6 to 24 carbon atoms or aromatic groups having 6 to 24 carbon atoms, a is 1, 2 or 3, b is 0, 1, or 2, with the condition that a and b are chosen such that: 4-ab ≥ 1, c for the remainder Y 1 0 and the remainder Y 2 1, in which the silane of the general formula I under conditions in which hydrolysis, e.g. in the presence of water, of the radical R 2 takes place, is polycondensed or copolycondensed with at least one other hydrolyzable silane compound, b) at least one solvent, and c) a photoactivatable compound which decomposes the photolabilizable group P upon photoactivation.

Description

[0001] The present invention relates to a specific heteropolymer, namely a silicic acid (hetero)poly(co)condensate with positive resist behavior, which is characterized by polycondensation or copolycondensation of specially modified silanes. The silicic acid (hetero)poly(co)condensates according to the invention can be used for a photoresist according to the invention that exhibits positive resist behavior. Furthermore, the invention relates to corresponding processes for producing the silicic acid (hetero)poly(co)condensates and to a process for photochemically structuring the photoresist according to the invention based on the silicic acid (hetero)poly(co)condensates.

[0002] Photoresists are frequently used today in the UV lithographic production of integrated circuits. A distinction is made between positive-tone resists, in which solubility is increased through interaction with light, and negative-tone resists, in which solubility is reduced. Increasing solubility is often achieved by creating functional groups or breaking bonds, thus reducing the molecular weight. When solubility is reduced, polymerization reactions generate products with a higher molecular weight than the starting material, which can then no longer be dissolved in the solvent.Photoresists with positive-tone behavior usually exhibit better resolution than negative-tone resists because the crosslinking reaction in the latter is often based on chain reactions which - compared to the individually induced bond breaks in positive-tone resists - have a larger reaction volume. To enable positive behavior, increased solubility must be generated. This can occur either through bond breaks in the polymer chain, i.e. a reduction in molecular mass, or through chemical reactions that result in the generation of other functional groups and thus lead to a change in polarity. Polar groups such as alcohol or carboxylic acid groups, but in principle also amino functions, are suitable for solubility in aqueous solvents. The reaction to form these functional groups can occur intrinsically or through additional additives or initiators.

[0003] Photoresists are often used either as sacrificial resists or as patternable functional layers. When used as sacrificial resists, the patterned photoresist layer serves as a mask for the deposition of inorganic layers or for etching the materials exposed between the structures. Etch patterning is the most common method. This results in a second requirement for the photoresist. It must remain stable under etching conditions, such as O2 plasma, and must not be removed as well.

[0004] The etch stability of purely organic photoresists can be improved by using inorganic components, partly because, in the case of silicon-organic components, the interaction of the plasma with the silicon-organic films, forming SiO, creates a surface film that is stable under the etching conditions. Based on this, several publications already report the incorporation of silicon-containing compounds into positive-tone photoresists. The resulting silicon-containing positive-tone photoresists are partly based on silicon-organic components.on two-component systems: One component consists of a silicon-containing polymer which is soluble in the aqueous developer, the other component of a polymer which is insoluble in aqueous solvents, such as DNQ, which reacts by interacting with actinic radiation and forms polar groups, whereby the second component and thus the entire photoresist becomes soluble in the aqueous developer after exposure [Y. Kimura, T. Etou, M. Kondo, US 20110008589A1; T. Aoai, K. Mitzutani, EP 410606 A2, 30.01.1991. [3] A. Tanaka, Radiat. Curin Polym. Sci. Technol. 19934381-386; DS Uh, CI Oh, DH Kim, H. C Yun, JK Lee, I. Nam, JS Kim, US 20070148586 A; K. Mizutani, H. Kanda, H. Inabe, US 20070065753 A1] In further studies, these two components, ie silicon-containing monomers and purely organic monomers which possess the photolabile groups, are linked by covalent bonds to form (block) copolymers [AH Gabor, RD Allen, P.Gallagher-Wetmore, CK Ober, Proc. SPIEE - The International Society for Optical Engineering, 1996, 2724, 410-417; EW Van der Drift, JC Van de Grampel, R. Puyenbroek, B. Rousseeuw, WO 9411788 A1; KG Sachdev, RW Kwong, MM Khojasteh, HS Sachdev, US 4665006 A; P. Foster, G. Spaziano, BB De, US 20050042542 A1]. Furthermore, the silicon-containing components can be implemented as so-called macromers by substitution in the side chains of the network even after the formation of the photolabile component network. All of these methods have the fundamental disadvantage that the positive etching properties of the silicon are diluted by the silicon-free components.

[0005] Other studies report the introduction of photolabile groups, e.g., as esters, into the side chains of the network composed purely of silicon-containing monomers. Examples include ladder-like networks, so-called polysilsesquioxanes, which possess photolabile groups in cyclohexyl side chains [J. Hatakeyama, M. Nakashima, I. Kaneko, S. Nagura, T. Ishihara, Proc. SPIEE - The International Society for Optical Engineering, 1998, 333362-72]. The introduction of these protecting groups often occurs by reacting hydroxyl groups of the silsesquioxane side chains with α-halocarboxylic acid esters [T. Nakamura, K. Tamura, T. Yamada, T. Hirayama, D. Kawana, T. Hosono, US20090068586 A1]. In addition, substituents with photolabile groups can be formed by hydrosilylation reactions, ie the catalyzed reaction of a C=C bond of the future substituent with Si-H groups of the silane, or by substitution of hydroxyl groups of polycyclic side chains (e.g. norbornenes) [K.Noda, K. Takemura, Y. Hamada, M. Nakashima, US 20050079443 A1] In addition to ester groups, substituents can also be bonded to the alkoxysilane which possess the above-mentioned DNQ group and are therefore intrinsically photolabile [T. Noguchi, K. Nito, H. Tomita, J. Seto, Polym. Microelectron. Proc. Int. Symp. 1990305-316.].

[0006] In further work, the light-induced reaction of polysilanes to polysiloxanes is used for patterning with positive behavior, since the reaction product is soluble in aqueous solvents [P Gallagher-Wetmore, GM Wallraff, RD Allen, Proc. SPIEE - The International Society for Optical Engineering, 19952438694-708]. Highly hydrolysis-sensitive photoresists, such as silazanes, can be hydrolyzed and decomposed under the influence of light with the protons formed by the catalyst and ambient moisture [W. Li, GS sandu, US 20110065050 A1]. The resulting ceramic-like layer is soluble in aqueous solvents and can be removed. However, since this layer can also be insulating and stable against the plasma used in the etching step, this structuring method follows the development with a further exposure step to form a structured ceramic-like SiO, layer.Another possibility for the introduction of photolabile groups is offered by sulfonamides [S. Kanagasabapathy, GG Barclay, US 20040161698 A1].

[0007] The water solubility of the photoresist can be further increased by additional substituents, such as fluorides [K. Noda, K. Takemura, Y. Hamada, M. Nakashima, US 20050079443 A1]. However, the incorporation of these substituents is not possible in an infinitely high proportion, as this would reduce the etching properties. The introduction of these substituents is also fundamentally possible for the present invention, e.g., through the combined hydrolysis and condensation of the alkoxysilane bearing the photolabile group and a fluorinated alkoxysilane.

[0008] Furthermore, it is possible to increase the resolution of the ORMOCER presented here ®The potential for enhancing the photoresist's performance in a photoresist with positive-tone behavior containing phosphorus can be increased by adding an additional additive that captures the reactive species that lead to the light-induced reaction, thereby preventing the reactive species from diffusing in large numbers into the unexposed areas and inducing the formation of soluble components there as well. Suitable substances for this purpose include amines, as reported in numerous other studies on photoresists with positive-tone behavior.

[0009] ORMOCER ®They are based on hydrolyzed and condensed alkoxysilanes or alkoxy element compounds, such as Ti, Zr. In systems composed of pure alkoxysilanes, the stable Si-C bond allows functional groups to be integrated into the material, which remain in the resulting material even after hydrolysis and condensation of the silane (mono-, di-, or trialkoxysilane). Transition metals, such as Zr or Ti, in contrast, form hydrolysis-sensitive bonds to carbon substituents. The integration of functional groups must therefore occur via stable chelate complexes, since only the metal-ligand bonds formed in this process are hydrolysis-stable.

[0010] The ORMOCER ®They form a class of materials which, due to the versatility of the functional groups that can be integrated into the alkoxysilanes, can possess properties of ceramic materials, silicones, organic polymers or even glasses [K.-H. Haas, Adv. Engin. Mater. 20002(9), 571-582.]. Due to the multitude of possible combinations, the mechanical, electrical, thermal and optical properties of thin ORMOCER ® -Layers can be varied over a wide range. Examples of functional ORMOCER ®-Layers are waveguide materials [N. Kondo, T. Hayashi, M. Popall, L. Fröhlich, R. Houbertz, S. Cochet, US 20090252471 A1], scratch-resistant coatings [K.-H. Haas, S. Amberg-Schwab, K. Rose, Thin Solid Films, 1999351, 198-203.], passivation layers for optical and electronic components [M. Popall, J. Kappel, M. Pilz, J. Schulz, J. Sol-Gel Sci. Technol. 19942, 157-160.], surface coating of soft, flexible polymer substrates and films [C. Sanchez, B. Man, P. Belleville, M. Popall, J. Mater. Chem. 2005, 15 (35-36)3559.] or of temperature-sensitive substrates [K.-H. Haas, Adv. Engin. Mater. 20002(9), 571-582.] as well as dirt-repellent, anti-adhesive or antistatic coatings [K.-H. Haas, S. Amberg-Schwab, K. Rose, Thin Solid Films, 1999351, 198-203.].

[0011] WO 2012 / 129380 A2 discloses a radical-initiated thiol-ene or thiol-yne "click" reaction that offers a simple and efficient route to various trialkoxysilanes. Trialkoxysilanes prepared in this way are obtained in quantitative to near-quantitative yield and with high purity without any or minimal purification. This approach tolerates a broad range of functional groups, and even complex alkenes react with the silane precursors. The modular nature of these radical-based thiol-ene or thiol-yne click reactions enables the coupling of a wide variety of side groups to silane compounds, which can then be coupled to a wide variety of surfaces to alter their material properties. Consequently, such radical-initiated thiol-ene and thiol-yne reactions offer simple and efficient methods for the preparation of an enormous number of surface-active functional trialkoxysilanes.

[0012] DE 198 22 721 A1 relates to a film-forming, selectively removable material for the temporary stabilization and / or functionalization of technical or biological surfaces based on inorganic / organic hybrid polymers and film-forming water- and / or alcohol-soluble polymers.

[0013] From JP 2012-180324 A, it is known to provide a thioether-containing alkoxysilane derivative that has excellent adhesive property-improving properties. The thioether-containing alkoxysilane derivative is a compound represented by Formula 1. [Where m is 1 or 2; n is 0 or 1; R is H, a 1-18C hydrocarbon or a 1-4C hydrocarbon substituted with 1-3C alkoxy; R is methyl or ethyl; and R is a divalent group represented by -CH-CH- or -CH(CH)-].

[0014] EP 1 265 103 A1 relates to an active component suitable for forming minute patterns such as semiconductor integrated circuits using a beam, for example, ultraviolet rays or far ultraviolet rays (including excimer lasers or the like); a photosensitive resin composition (resist composition) using this component; and a method for forming a pattern using this component.

[0015] Based on this, it was the object of the present invention to produce the previously presented hybrid polymer materials (omocers or silicic acid (hetero)poly(co)condensates), in which the previously mentioned good properties of the omocers are supplemented by a positive tone character. It is also the object of the present invention to specify corresponding monomeric materials from which the corresponding omocer polymers can be produced or to demonstrate applications of such polymer systems. It is further the object of the present invention to demonstrate production possibilities for the aforementioned substance classes.

[0016] These objects are achieved according to a photoresist having the features of patent claim 1, a method for photochemically structuring the photoresist according to the invention having the features of patent claim 7, a method for producing a silicic acid (hetero)poly(co)condensate having the features of patent claim 10, and a silicic acid (hetero)poly(co)condensate with positive resist behavior having the features of patent claim 12. The respective dependent patent claims represent advantageous developments.

[0017] According to a first aspect of the present invention, a photoresist with positive resist behavior according to the features of claim 1 is thus provided, consisting of a) a silicic acid (hetero)poly(co)condensate with positive resist behavior, producible from according to the general formula I [P-(Y 1 ) c -X-(Y 2 ) c ] a Si(R 1 )b (R 2 ) 4-a-b Formula 1 described, where P represents a photolabilizable or photolabile group, and is selected from the group consisting of radicals of the general formula IVwherein R 3 is selected from the group consisting of linear or branched alkyl radicals having 1 to 18 carbon atoms, preferably tertiary alkyl groups, such as t-butyl, 1-ethylnorbornyl, 1-methylcyclohexyl, 1-ethylcyclopentyl, 2-(2-ethyl)adamantyl or t-amyl groups; trialkylsilyl groups, such as trimethylsilyl, triethylsilyl or dimethyl-tert-butylsilyl groups; ester groups, such as t-butoxycarbonyloxy (t-BOC) or oxoalkyl groups (e.g. 3-oxocyclohexyl group), X represents the grouping shown below:where Z is selected from the group consisting of S, O, NR 4 , C(R 4 )2, R 4is the same or different at each occurrence and is selected from the group consisting of hydrogen and linear or branched alkyl radicals having 1 to 18 carbon atoms, cycloaliphatic groups having 6 to 24 carbon atoms or aromatic groups having 6 to 24 carbon atoms and n is 1, Y 1 and Y 2 are the same or different at each occurrence and are selected from the group consisting of saturated or unsaturated alkylene groups having 1 to 18 carbon atoms, cycloaliphatic groups having 6 to 24 carbon atoms or aromatic groups having 6 to 24 carbon atoms, R 1 is selected from the group consisting of linear or branched alkyl radicals having 1 to 18 carbon atoms, cycloaliphatic groups having 6 to 24 carbon atoms or aromatic groups having 6 to 24 carbon atoms, R 2 a group -OR 3 where R3 is selected from the group consisting of linear or branched alkyl radicals having 1 to 18 carbon atoms, cycloaliphatic groups having 6 to 24 carbon atoms or aromatic groups having 6 to 24 carbon atoms, a is 1, 2 or 3, b is 0, 1, or 2, with the condition that a and b are chosen such that: 4-ab ≥ 1, c for the remainder Y 1 0 and the remainder Y 2 1 iswherein the silane of the general formula I under conditions in which hydrolysis, e.g. in the presence of water, of the radical R 2 takes place, polycondenses or copolycondenses with at least one other hydrolyzable silane compound b) at least one solvent, and c) a photoactivatable compound which decomposes the photolabilizable group P upon photoactivation.

[0018] The silane according to general formula I has a photolabilizable or photolabile group. A photolabilizable group refers to functional groups that can be cleaved or modified indirectly by photochemical induction. This requires an auxiliary reagent that decomposes upon irradiation, releasing an active species that cleaves or modifies the photolabilizable group. A photolabile group is directly sensitive to light, meaning that direct modification or cleavage of this photolabile group occurs upon light irradiation. These groups preferably exhibit light sensitivity in the visible range of the spectrum, but UV or infrared sensitivity can also be present. The P group can be selected depending on the desired application and tailored to the corresponding requirements.

[0019] The group R 2 represents an oxo group, for example an alkoxy group, in particular an ethoxy or methoxy group. The group R 2 is thus sensitive to hydrolysis, so that the corresponding silane according to formula I can be crosslinked by polycondensation or copolycondensation under appropriate conditions.

[0020] The indices and b can be freely chosen according to the conditions specified above; an exemplary preferred embodiment provides: b=0 a=1.

[0021] The present invention thus offers an extension of the possible reaction paths for introducing the photolabile group. Here, the ester is bonded to the underlying alkoxysilane, for example, by a Michael-type reaction of a thiol group with a C=C bond. Therefore, carboxylic acid esters containing double bonds, in which the C=C groups are bonded on the carboxylate side, are generally suitable as substituents with photolabile groups. Particular preference is given to (meth)acrylic acid esters, which are particularly activated for the addition of a thiol by the conjugation of C=C and C=O bonds. The alkoxy group of the photolabile ester should typically be based on a tertiary alcohol in order to increase the driving force for acid-catalyzed hydrolysis, i.e., deprotection by the photoacid generated by actinic radiation.

[0022] The compound according to the general formula I is prepared by reacting the compounds of the general formula II with compounds of the general formula III. In this case, a compound of the general formula II [X-(Y 1 ) c -X-(Y 2 ) c ] a Si(R 1 ) b (R 2 ) 4-a-b Formula II with a compound of the general formula III P-(Y 1 ) c - X 2 Formula III to the compound of general formula I, wherein in the compounds of general formulas II and III the radicals P, Y 1 , Y 2 , R 1 , R 2 , a, b and c have the meaning given above and X 1 and X 2 are functional groups that react to form functional linkage X.

[0023] The groups X 1 and X 2are functional groups that react to form the functional link X.

[0024] The present invention thus offers an extension of the possible reaction paths for introducing the photolabile group. Here, the ester is bonded to the parent alkoxysilane, for example, by a Michael-type reaction of a thiol group with a C=C bond. Therefore, carboxylic acid esters containing double bonds, in which the C=C groups are bonded on the carboxylate side, are generally suitable as substituents with photolabile groups. Particular preference is given to (meth)acrylic acid esters, which are particularly activated for the addition of a thiol by the conjugation of C=C and C=O bonds. The alkoxy group of the photolabile ester should typically be based on a tertiary alcohol in order to increase the driving force for acid-catalyzed hydrolysis, i.e., deprotection by the photoacid generated by actinic radiation.

[0025] The stoichiometric ratio of the compounds of general formula II and III naturally depends on the type of groupings X used 1 and X 2 to establish the link X groups X are preferred 1 and X 2 chosen which allow the most equimolar ratio of the compounds of formula II and III possible, so that a high economy of the reaction is given.

[0026] The photolabilizable groups P present according to the invention are characterized by the fact that they can be modified by an appropriate reagent generated upon irradiation. In the example case of the grouping according to the above-mentioned formula IV, the modification takes place by saponification of the ester, so that a relatively hydrophilic grouping, for example the free carboxylic acid, can be produced from a relatively hydrophobic residue, which is accompanied by a noticeable change in the polarity of the silane. In the case where the silane is polymer-bound, e.g., in an omocer network (as described in more detail below), the change in polarity naturally also applies to the polycondensates or copolycondensates produced.

[0027] The previously mentioned preferred residues R 3 all represent excellent leaving groups, so that easy and comprehensive saponification of the ester group is possible.

[0028] Preferred photolabile groups that can be directly chemically modified by irradiation are selected in particular from the group consisting of groups that can be dissociated by photoradiation. Such photolabile groups are mentioned, for example, in EP 0 568 476 A2; with regard to possible photolabile groups that can be used for the present invention, reference is also made in particular to this publication. All of the photolabile groups mentioned therein can also be used according to the present invention. A particularly preferred photolabile group is the 1,2-diazonaphthoquinone group.

[0029] A preferred functional link X is selected from one of the following groupings:orwhere Z is selected from the group consisting of S, O, NR 4 , C(R 4 )2, R 4is the same or different at each occurrence and is selected from the group consisting of hydrogen and linear or branched alkyl radicals having 1 to 18 carbon atoms, cycloaliphatic groups having 6 to 24 carbon atoms or aromatic groups having 6 to 24 carbon atoms and n is 0 or 1.

[0030] The group X shown top left can be prepared, for example, by addition reaction, while the group X shown right can be obtained, for example, by cross-coupling etc.

[0031] Thus, the groups X contained in the formulas III given above are 1 and X 2 prefers groups that react with each other by addition, substitution, cross-coupling or metathesis to form the functional linkage X.

[0032] The following are particularly preferred pairings of groups X 1 and X 2which can be used according to the present invention to obtain the functional linkage X. In a first variant, X 1 the grouping shown below and X 2 is selected from the following groupings or

[0033] Here Hal means Cl, Br, or I.

[0034] The variables contained in the aforementioned formulas correspond to the definitions already given above. This also applies to all of the formulas mentioned below and the variables they contain. To avoid repetition and for clarity, these are not specified in detail, but correspond to the definitions given above.

[0035] According to the previously mentioned pairing of the groups X 1 and X 2the functional linkage X can be prepared in particular by addition of the group HZ - to a double bond or by nucleophilic substitution of the corresponding group HZ - to an alkyl halide.

[0036] Alternatively and equally preferably, the polarity of the two groups X 1 and X 2 According to this variant, it is preferred if X 1 selected from the following groupings or and X 2 represents the grouping shown below, where Hal means Cl, Br, or I.

[0037] In a particularly preferred variant, the silane of general formula I has the following structural formula. The corresponding silane can be prepared by reacting compounds of general formula II with the following structure and a compound of general formula III with the following structure. The silane of general formula I is obtained by thiol-ene addition of the compound of general formula II and the compound of general formula III.

[0038] The invention also relates to a process product of the previously presented process according to the invention, ie a silane with positive resist behavior according to the general formula I [P-(Y 1 ) c -X-(Y 2 ) c ] a Si(R 1 ) b (R 2 ) 4-a-b Formula 1

[0039] All of the parameters used (ie the variables specified in formula I) or preferred embodiments with regard to the variables correspond to embodiments already made previously.

[0040] In particular and particularly preferably, the silane according to the invention has the following structure

[0041] According to a further aspect, the present invention relates to a process for the preparation of a silicic acid (hetero)poly(co)condensate having positive resist behavior from a silane of the general formula I as defined above, in which a silane according to the general formula I is reacted under conditions in which hydrolysis, e.g. in the presence of water, of the radical R 2 takes place, polycondensed or copolycondensed with at least one other hydrolyzable silane compound.

[0042] In the simplest case, for example, a previously described silane of general formula I can be subjected to a polycondensation hydrolysis reaction. The hydrolysis can be carried out, for example, by adding water, but can also be carried out by selecting suitable catalysts or under suitable conditions in the absence of water.

[0043] According to a further variant, mixtures of different silanes of general formula I can also be copolycondensed. For example, an embodiment in which the parameters a and b for the silane of formula I are chosen differently is conceivable; for example, silanes with a=1 and b=0 can be copolycondensed with silanes of formula I where a=1 or 2 and b=0 or 1. Through the aforementioned modification, both the concentration of the photolabilizable or photolabile group P and the reactivity, i.e., the hydrolysis susceptibility of the silane, can be specifically adjusted.

[0044] According to a further embodiment, in addition to one or more of the aforementioned silanes of formula I, copolycondensation can be carried out with another hydrolyzable silane. For this purpose, alkoxysilanes, for example, can be used. These alkoxysilanes can be unmodified (i.e., for example, they do not carry a photolabilizable group P) or they can also carry further reactive radicals, for example radicals with unsaturated compounds such as unsaturated double bonds, for example (meth)acrylic acid or (meth)acrylate groups. The presence of further reactive organic radicals thus enables cross-linking of the siloxane backbone obtained by polycondensation.

[0045] According to the invention, the aforementioned hydrolysis reaction is carried out in the presence of a catalyst, preferably ammonium fluoride.

[0046] By-products resulting from polycondensation, in particular compounds according to the formula R 2H are preferably separated from the reaction mixture during and / or after completion of the reaction, in particular by distillation. In particular, alcohols such as methanol or ethanol (the two correspond to the choice of the radical R 2 can thus be easily and almost completely separated from the reaction mixture, so that the equilibrium position of the polycondensation reaction is shifted towards the product side.

[0047] According to a further aspect, the present invention relates to process products of the previously presented polycondensation process, namely silicic acid (hetero)poly(co)condensates with positive resist behavior. Due to the possible crosslinking during the (co)polycondensation, it is not possible to specify a corresponding unambiguous structural formula for the resulting process products. However, the silicic acid (hetero)poly(co)condensate is based on a siloxane network. Depending on whether, for example, additional reactive groups are present, further crosslinking can be carried out, for example by UV irradiation, etc., resulting in an additional, second, organic network.

[0048] The silicic acid (hetero)poly(co)condensates (ORMOCERE) according to the invention exhibit positive resist behavior, in which a chemical modification of the silicic acid (hetero)poly(co)condensate occurs upon photoirradiation (with a photolabile group) or upon addition of a corresponding reagent that forms a reactive species upon photoirradiation that reacts with the photolabilizable group P. This can, for example, be the saponification of an existing ester group (photolabilizable group) or the direct cleavage of an azo group present, for example (photolabile group). In this respect, the silicic acid (hetero)poly(co)condensates according to the present invention exhibit a defined photosensitivity, which leads to changes in properties.

[0049] ORMOCER ®e already offer a wide portfolio of application possibilities and adjustable properties as a separate material class, which is partly due to the photostructurability of the ORMOCER ® e is determined. The currently exclusively used method of negative resist repeatedly reaches its limits due to the organic solvents required in the development step. Users often require photoresists that are soluble in aqueous systems. The present invention offers a solution to this problem, as the exposed areas of the system developed here are soluble in aqueous solutions (e.g., TMAH). In combination with the already very broad application area of ​​ORMOCER ® This opens up new application possibilities for the class of materials described in the present invention.

[0050] This property of the silicic acid (hetero)poly(co)condensates according to the present invention can be used in particular for photoresists. Therefore, a further aspect of the present invention relates to a photoresist with positive resist behavior, comprising a silicic acid (hetero)poly(co)condensate with positive resist behavior as described above, at least one solvent, preferably propylene glycol monomethyl ether 1,2-acetate (PGMEA, CAS No.: 108-65-6), methyl isobutyl ketone, n-propyl acetate, butyl acetate, butyl lactate, ethanol, or mixtures thereof, and, in the case where the photoresist is based on a silicic acid (hetero)poly(co)condensate with a photolabilizable group P, a photoactivatable compound that decomposes the photolabilizable group P upon photoactivation.

[0051] The photoresist can be applied to substrates, for example, and cured by evaporation of the solvent it contains. This allows a homogeneous and thin layer to be created on any substrate.

[0052] Preferred photoactivatable compounds are in particular photoacid generators, which are preferably formed from the group consisting of onium salt photoacid generators, halogen-containing photoacid generators, sulfonic acid or sulfonate-containing photoacid generators.

[0053] Preferred acid generators that can also be used according to the present invention are mentioned, for example, in US 2005 / 007944 A1. All of the photoacid generators described therein can also be used with preference according to the present invention.

[0054] Furthermore, it is possible to increase the resolution of the ORMOCER presented here ®The solvency of a photoresist with positive-tone behavior can be increased by adding an additional additive that captures the reactive species that lead to the light-induced reaction, thus preventing the reactive species from diffusing in large numbers into the unexposed areas and inducing the formation of soluble components there. Suitable additives for this purpose include amines, as reported in numerous other studies on photoresists with positive-tone behavior.

[0055] Furthermore, the resolution in photoresists based on positive-tone behavior is generally better than in the corresponding negative-tone photoresists. Thus, it can be expected that the resolution will be higher compared to conventional ORMOCER ® en is improved, which can be further increased by the contact exposure possible in this case.

[0056] Preferred acid generators that can also be used according to the present invention are mentioned, for example, in US 2005 / 007944 A1. All of the photoacid generators described therein can also be used with preference according to the present invention.

[0057] In addition, the invention relates to a method for photochemical structuring of a previously presented photoresist according to the invention, in which a substrate is coated with the photoresist and the resulting layer of the photoresist is exposed to radiation in certain areas, wherein the photoactivatable compound is activated and thereby the photolabilizable group P is decomposed, or the photolabile group P is decomposed.

[0058] The photoresist can be exposed to specific areas, for example, by partially shading the substrate. For this purpose, methods known from the state of the art, such as UV lithography or multiphoton polymerization, are preferably used.

[0059] After exposure, the substrate provided with the photoresist is preferably subjected to a development step, wherein the coating is treated with an aqueous alkaline solution, in particular an aqueous solution of tetramethylammonium hydroxide.

[0060] By treating the coating, i.e., the photoresist layer, with an aqueous-alkane solution, the areas where decomposition of the photolabilizable group P or the photolabile group P has occurred are dissolved or at least partially dissolved from the polymer matrix. This results in a structural change in the photoresist layer. The unmodified areas, which, for example, exhibit greater hydrophobicity than the areas of the silicic acid (hetero)poly(co)condensate modified by exposure, remain largely intact.

[0061] According to a further preferred embodiment, the coating is thermally treated after application and / or after exposure, preferably at temperatures of 60 to 200 °C, more preferably from 100 to 140 °C and / or preferably over a period of 1 s to 10 min, more preferably from 30 s to 2 min.

[0062] The present invention is described in more detail with reference to the following exemplary embodiments as well as the attached example and the figure, without, however, limiting the invention to the preferred embodiments shown.

[0063] The invention describes the preparation and structuring of an inorganic-organic hybrid polymer based on ORMOCER ®en (organically modified ceramics, registered trademark of the Fraunhofer Society) and the corresponding underlying monomers. This novel hybrid polymer is characterized by the fact that, after application as a layer, it reacts to treatment with actinic radiation with increased solubility in aqueous solvents. This makes it possible to structure the initially uniformly applied polymer layer with actinic radiation using suitable processes (such as UV lithography or multiphoton polymerization). The increase in solubility due to interaction with light is referred to as positive behavior, since the resulting structures are an image of the mask used or the exposure pattern.

[0064] Light-induced decomposition of a catalyst can initiate photolytic decomposition, thus enabling the material to be structured. The underlying reaction is the acid-catalyzed hydrolysis of an ester, which is frequently used for photoresists with positive behavior. The ester function acts as a protecting group for a carboxylic acid function, which, compared to the reactant, has increased solubility in aqueous media and is therefore also referred to as a photolabile group. The ester group is part of an ORMOCER. ® s, ie an oligosiloxane, which was previously produced by hydrolysis and condensation reactions. The basic structure of the ORMOCER ® It thus forms an organically modified, inorganic Si-O network. This can also be modified by adding other so-called crosslinkers.

[0065] The resulting photostructured ORMOCER layer can be used as a so-called sacrificial resist for the subsequent structuring of layers underneath the ORMOCER or, depending on additional functional groups, as a photostructured, functional coating.

[0066] The organic substituents of the ORMOCER ® The underlying alkoxysilanes can, if they have corresponding functional groups, enhance the light-induced polymerizability of the ORMOCER ® s. So far, only ORMOCER ® e with negative tone behavior, e.g., by polymerizable methacrylate, styryl, epoxy, or norbornene-containing groups. In contrast to the above-mentioned two-component systems or (block) copolymers, the distribution of the silicon ions in the ORMOCER according to the invention is ®en very homogeneous, which is why this class of materials is very well suited as a basis for the development of novel positive resists.

[0067] The photolabile group is introduced into the ORMOCER by a thiol-ene reaction ® The underlying alkoxysilane is then integrated. The SiO network is then formed through hydrolysis and condensation reactions with suitable catalysts. Typical catalysts for these reactions are acids or bases. The challenge lies in retaining the acid-labile group, which can be cleaved even under strongly alkaline conditions, in the alkoxysilane and preventing it from being cleaved again. This is achieved in the present invention using ammonium fluoride catalysis. In the photochemical structuring of negative-tone ORMOCER ® When using UV lithography, a distance exposure is absolutely necessary, since even after the temperature treatment in the prebake step, the ORMOCER ®-Film is not yet solid and contact exposure can damage or heavily contaminate the mask. Examples of implementationExample 1 - Synthesis of the monomer

[0068] Monomer production of an ORMOCER ® s with photolabile substituents.

[0069] In a flask purged with argon, 55.45 mmol (7.886 g) of t-butyl methacrylate are placed and diluted with 16.99 g of n-propyl acetate. Then, 55.45 mmol (13.222 g) of 3-mercaptopropyltriethoxysilane are added.

[0070] A freshly prepared 88% KOH solution (3.13 g, 0.55 mmol KOH) is slowly added dropwise to the mixture.

[0071] The conversion to the silane according to the invention takes place by thiol-ene reaction of the thiol group to the unsaturated group of the acrylate group. Example 2 - Preparation of the polycondensate

[0072] After the reaction in Example 1 is complete, 101 µl of a 1.1 M NH4F solution and 16.6 mmol (0.299 g) of water are added to one-fifth of the reaction mixture, and the reaction mixture is stirred at 25°C for 16 h. Subsequently, 22.8 ml of PGMEA are added to the reaction mixture, and the synthesis product is obtained by distillation of the volatile components released during hydrolysis and condensation. The PGMEA solvent is left in the reaction mixture, thus producing a ready-to-use photoresist. Example 3 - Structuring and developing the photoresist

[0073] The synthesis product, which already contains the solvent PGMEA, is applied to a substrate by spin coating after the addition of a photoacid generator (PAG, cyracure 6975). The thickness of the photoresist can be adjusted by dilution, for example 500 - 1000 nm. After spin coating, a pre-bake is carried out at 120°C for 1 minute. The layer is then exposed in a mask exposure unit (Hg vapor lamp, I-line) for 30 seconds. The next step is a post-exposure bake at 120°C for a further 1 minute. The exposed areas can then be developed with an aqueous alkaline solution (TMAH). The unexposed product can also be removed in a later process (stripping), for example using methyl isobutyl ketone. Example 4 - Etch stability

[0074] The layer obtained after photostructuring and development was then exposed to an argon plasma (power: 300 W, argon pressure: 1.0 * 10.3 mbar). The plot of the time-dependent removal shows that the ORMOCER underlying this invention ® with positive-tone behavior towards a backsputtering process (argon plasma) is at least as stable as conventionally cross-linked ORMOCER ® e ( Fig. 1).

[0075] ORMOCER ® e already offer a wide portfolio of application possibilities and adjustable properties as a separate material class, which is partly due to the photostructurability of the ORMOCER ®e is determined. The currently exclusively used method of negative resist repeatedly reaches its limits due to the organic solvents required in the development step. Users often require photoresists that are soluble in aqueous systems. The present invention offers a solution to this problem, as the exposed areas of the system developed here are soluble in aqueous solutions (e.g., TMAH). In combination with the already very broad application area of ​​ORMOCER ® This opens up new application possibilities for the class of materials described in the present invention.

[0076] Furthermore, the resolution in photoresists based on positive-tone behavior is generally better than in the corresponding negative-tone photoresists. Thus, it can be expected that the resolution will be higher compared to conventional ORMOCER ®en is improved, which can be further increased by the contact exposure possible in this case.

Claims

[1] Photoresist with positive resist behavior, consisting of a) a silicic acid (hetero)poly(co)condensate with positive resist behavior, preparable from a silane according to the general formula I [P-(Y 1 ) c -X-(Y 2 ) c ] a Si(R 1 ) b (R 2 ) 4-a-b Formula 1 where P is a photolabilizable group and is selected from the group consisting of radicals of the general formula IVwherein R 3is selected from the group consisting of linear or branched alkyl radicals having 1 to 18 carbon atoms, preferably tertiary alkyl groups, such as t-butyl, 1-ethylnorbornyl, 1-methylcyclohexyl, 1-ethylcyclopentyl, 2-(2-ethyl)adamantyl or t-amyl groups; trialkylsilyl groups, such as trimethylsilyl, triethylsilyl or dimethyl-tert-butylsilyl groups; ester groups, such as t-butoxycarbonyloxy (t-BOC) or oxoalkyl groups (e.g. 3-oxocyclohexyl group), X represents the grouping shown below:where Z is selected from the group consisting of S, O, NR 4 , C(R 4 )2, R 4 is the same or different at each occurrence and is selected from the group consisting of hydrogen and linear or branched alkyl radicals having 1 to 18 carbon atoms, cycloaliphatic groups having 6 to 24 carbon atoms or aromatic groups having 6 to 24 carbon atoms and n is 1, Y 1 and Y 2 are the same or different at each occurrence and are selected from the group consisting of saturated or unsaturated alkylene groups having 1 to 18 carbon atoms, cycloaliphatic groups having 6 to 24 carbon atoms or aromatic groups having 6 to 24 carbon atoms, R 1 is selected from the group consisting of linear or branched alkyl radicals having 1 to 18 carbon atoms, cycloaliphatic groups having 6 to 24 carbon atoms or aromatic groups having 6 to 24 carbon atoms, R 2 a group -OR 3 where R 3 is selected from the group consisting of linear or branched alkyl radicals having 1 to 18 carbon atoms, cycloaliphatic groups having 6 to 24 carbon atoms or aromatic groups having 6 to 24 carbon atoms, a is 1, 2 or 3, b is 0, 1, or 2, with the condition that a and b are chosen such that: 4-ab ≥ 1, c for the remainder Y 1 0 and the remainder Y 2 1, in which the silane of the general formula I under conditions in which hydrolysis, e.g. in the presence of water, of the radical R 2 takes place, polycondensed or copolycondensed with at least one other hydrolyzable silane compound, b) at least one solvent, and c) a photoactivatable compound which decomposes the photolabilizable group P upon photoactivation. [2] Photoresist according to claim 1, characterized by that the silane of general formula I has the following structure [3] Photoresist according to one of the preceding claims, characterized by that the silane of the general formula I is prepared by reacting a compound of general formula II [X-(Y 2 ) c ] a Si(R1 ) b (R 2 ) 4-a-b Formula II with a compound of the general formula III P-(Y 1 ) c -X 2 Formula III is obtained, wherein in the compounds of general formulas II and III the radicals P, Y 1 , Y 2 , R 1 , R 2 , a, b and c have the meaning given above and X 1 represents the grouping shown below and X 2 selected from the following groups or where Hal means Cl, Br, or I and n and R 4 as defined above. [4] Photoresist according to the preceding claim, characterized by , that the compound of general formula III has the following structure and the compound of general formula II has the following structure, wherein the silane of general formula I is obtained by thiol-ene addition of the compound of general formula II and the compound of general formula III. [5] Photoresist with positive resist behavior according to one of the preceding claims, characterized by that the at least one solvent is selected from the group consisting of propylene glycol monomethyl ether 1,2-acetate (PGMEA, CAS No.: 108-65-6), methyl isobutyl ketone, n-propyl acetate, butyl acetate, butyl lactate, ethanol or mixtures thereof. [6] Photoresist according to one of the preceding claims, characterized by that the photoactivatable compound is a photoacid generator which is in particular selected from the group consisting of onium salt photoacid generators, halogen-containing photoacid generators, sulfonic acid- or sulfonate-containing photoacid generators. [7] Method for photochemical structuring of a photoresist according to one of the preceding claims, in which a substrate is coated with the photoresist and the resulting layer of the photoresist is exposed to radiation in regions, wherein a) the photoactivatable compound is activated and thereby the photolabilizable group P is decomposed, or b) the photolabile group P is decomposed. [8] Method according to the preceding claim, characterized by that the photoresist is subjected to a development step after exposure, wherein the coating is treated with an aqueous alkaline solution, in particular an aqueous solution of tetramethylammonium hydroxide. [9] Method according to one of the two preceding claims, characterized bythat the coating is thermally treated after application and / or after exposure, preferably at temperatures of 60 to 200 °C, more preferably from 100 to 140 °C and / or preferably over a period of 1 s to 10 min, more preferably from 30 s to 2 min. [10] Process for the preparation of a silicic acid (hetero)poly(co)condensate with positive resist behavior from a silane of the general formula I, in which a silane according to the general formula I [P-(Y 1 ) c -X-(Y 2 ) c ] a Si(R 1 ) b (R 2 ) 4-a-b Formula 1 where P, Y 1 , Y 2 , R 1 , R 2 , X, a, b, c have the meaning given in claim 1, under conditions in which hydrolysis, e.g. in the presence of water, of the radical R 2 takes place, polycondenses or is copolycondensed with at least one other hydrolyzable silane compound, characterized by that the reaction is carried out in the presence of a catalyst, preferably ammonium fluoride. [11] Method according to the preceding claim, characterized by that condensation products obtained during and / or after completion of the reaction, in particular compounds according to the formula R 2 H, removed from the reaction mixture, in particular distilled off. [12] Silicic acid (hetero)poly(co)condensate with positive resist behavior, producible by a process according to one of claims 10 to 11.

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