Resist film forming composition, resist layer, and semiconductor device manufacturing method

Abstract

[Problem] To provide a resist film forming composition capable of forming a resist pattern excellent in adhesion to a workpiece in EUV lithography. [Solution] In an embodiment, this resist film forming composition contains at least one member selected from the group consisting of organometallic structures composed of metal oxide clusters and organic ligands, and a sensitizer.

Description

A composition for forming a resist film, a resist layer, and a method for manufacturing a semiconductor device. 【0001】 This embodiment relates to a resist film forming composition, a resist layer, and a method for manufacturing a semiconductor device. 【0002】 In recent years, with the miniaturization of semiconductor devices, the mass production application of extreme ultraviolet (EUV) lithography technology has been progressing. In EUV lithography, high sensitivity, high resolution, low roughness, and excellent critical dimension (CD) uniformity are required to achieve high precision in pattern formation. 【0003】 To meet these demands, metal oxide resists (MOR), which are primarily composed of metal oxides, are attracting attention. MOR possesses high absorption capacity for EUV light and excellent etching resistance, and also exhibits high performance as a non-chemically amplified resist, making it a promising candidate for next-generation resist materials. 【0004】 However, due to its composition, MOR contains high-density metallic elements that strongly absorb EUV light, which easily leads to differences in EUV light absorption between the upper and lower surfaces of the resist film. As a result, the exposure reaction becomes non-uniform in the film thickness direction, and the cross-sectional shape of the pattern tends to become an inverted triangle. Furthermore, the non-uniformity of the exposure reaction and the reduced reactivity on the lower surface of the film reduce adhesion to the workpiece, making pattern collapse more likely to occur during the development process. 【0005】 Therefore, the present invention provides a resist film forming composition that enables the formation of a resist pattern with excellent adhesion to the workpiece in EUV lithography. 【0006】 The resist film forming composition according to this embodiment comprises at least one organometallic structure composed of a metal oxide cluster and an organic ligand, and a sensitizer. 【0007】This is a cross-sectional view showing an example of a method for manufacturing a semiconductor device according to the first embodiment. an enlarged cross-sectional view of the region P shown by the dotted line in Figure 3 in the first embodiment. This is a cross-sectional view showing an example of a method for manufacturing a semiconductor device according to the second embodiment. This is a cross-sectional view showing an example of a method for manufacturing a semiconductor device according to the second embodiment. This is a cross-sectional view showing an example of a method for manufacturing a semiconductor device according to the second embodiment. This is an enlarged cross-sectional view of the region P shown by the dotted line in Figure 8 in the second embodiment. 【0008】 Embodiments of the present invention will be described below with reference to the drawings. These embodiments are not limiting to the present invention. The drawings are schematic or conceptual. The same elements are denoted by the same reference numerals in the specification and the drawings. 【0009】 <First Embodiment> First, a method for manufacturing a semiconductor device according to the first embodiment will be described. Figures 1 to 5 are cross-sectional views showing an example of a method for manufacturing a semiconductor device according to the first embodiment. 【0010】 The method for manufacturing a semiconductor device according to the first embodiment includes forming a first resist film containing metal oxide fine particles and a sensitizer on a workpiece, forming a second resist film containing an organometallic structure on the first resist film, irradiating the resist layer containing the first and second resist films with EUV light, developing the resist layer to form a resist pattern. In other words, the method for manufacturing a semiconductor device according to this embodiment includes a method for forming a resist pattern, which includes the steps of forming a first resist film on a workpiece (first step), forming a second resist film on the first resist film (second step), irradiating the resist layer with EUV light (third step), and developing the resist layer to form a resist pattern (fourth step). Each step will be described in detail below. 【0011】(First Step) As shown in FIG. 1, in the first step, a first resist film 21 is formed on the workpiece 10. Specifically, first, a composition for forming the first resist film 21 is prepared. The composition for forming the first resist film 21 contains at least metal oxide fine particles and a sensitizer. 【0012】 The metal oxide fine particles (nanoparticles) are oxides of a metal element M that have high absorbability to EUV light (extreme ultraviolet light, for example, having a wavelength of 10 nm to 100 nm or may have a wavelength of 13.5 nm). The particle size of the metal oxide fine particles is not particularly limited, but for example, it is 10 to 100 nm. The metal oxide fine particles may be crystalline or amorphous (amorphous structure). 【0013】 Examples of the metal element M include Sn, Zn, Hf, Zr, Sb, Ti, In, Bi, Al, Fe, Ni, Co, Cr, and Mg. The metal oxide fine particles containing these metal elements M are not particularly limited, and known ones conventionally applied can be used. Among these, from the viewpoints of absorbability to EUV light and generation efficiency of secondary electrons, for example, as the metal oxide fine particles, SnO ２ , ZnO, ZrO ２ , HfO ２ are preferable, and SnO ２ , ZnO, HfO ２ are more preferable. By the composition for forming the first resist film containing these metal oxide fine particles, the exposure sensitivity and pattern forming performance of the first resist film 21 are improved. 【0014】 The sensitizer is an additive for improving the sensitivity to EUV light. The sensitizer is not particularly limited, and known ones conventionally applied can be used. 【0015】 As the sensitizer, a sensitizer that improves the sensitivity of the resist by enhancing the absorption efficiency of EUV light and promoting the generation of secondary electrons may be used. Examples of such a sensitizer include metal salts such as Sn, In, and Te; TeO ２Metal oxide nanoparticles such as etc.; organometallic compounds such as organic Sn and Ge compounds and the like can be mentioned. Among these, Sn salts (tin salts), In salts (indium salts), TeO ２ nanoparticles, Zn salts (zinc salts), and organic Sn compounds are preferable. By including any one or more of these sensitizers in the composition for forming the first resist film, effects such as improvement of exposure sensitivity, promotion of secondary electron generation, reduction of defect rate, and improvement of pattern accuracy can be obtained. 【0016】 As the sensitizer, known sensitizers conventionally applied to metal oxide resist (MOR: Metal Oxide Resist) that absorb EUV light and generate radicals or ions that promote chemical reactions may be used. Such sensitizers include organic halogen compounds such as trifluoromethylbenzene derivatives and iodinated aromatics; carboxylic acid-based sensitizers such as benzoic acid derivatives and phthalic acid derivatives; benzoic acid-based sensitizers such as p-methoxybenzoic acid, p-nitrobenzoic acid, and fluorobenzoic acid; sulfonic acid-based sensitizers such as p-toluenesulfonic acid, benzenesulfonic acid, and naphthalenesulfonic acid; photoacid generators (PAG: Photoacid Generator) such as sulfonic acid type PAG (trifluoromethanesulfonic acid ester), arylazonium type (phenyldiazonium salt), and onium salt type (imidazolium, sulfonium); photoacid generator (PAG) analog substances such as non-conventional inorganic PAG and metal complex type PAG; aromatic ketones such as benzophenone and acetophenone derivatives and the like can be mentioned. Among these, from the viewpoint of the influence on the interface with the second resist film 22, benzoic acid-based sensitizers and sulfonic acid-based sensitizers are preferable. Here, benzoic acid-based sensitizers and sulfonic acid-based sensitizers are generally acids with stronger binding force than carboxylic acids. 【0017】 The composition for forming the first resist film preferably contains at least any one or more of the sensitizers that promote the generation of secondary electrons, and more preferably contains any one or more of the sensitizers that promote the generation of secondary electrons and any one or more of the sensitizers that generate radicals or ions that promote chemical reactions. 【0018】The first resist film forming composition may contain a resin material. The resin material is not particularly limited, and organic polymers known as resin materials for resists in EUV lithography can be used. Specific examples of such resin materials include phenolic polymers, acrylic polymers, molecular resists, and fluororesins. 【0019】 Examples of phenolic polymers include poly(hydroxystyrene) and novolac resins. Phenolic polymers exhibit alkali developability through deprotection reactions with acids. Furthermore, under EUV light, phenolic polymers themselves ionize, activating acid generators. 【0020】 Examples of acrylic polymers include polymethacrylic acid and polyacrylic acid derivatives. Acrylic polymers have a high glass transition temperature (Tg) and are effective in suppressing acid diffusion. Furthermore, acrylic polymers exhibit a large difference in solubility before and after deprotection, enabling the creation of high-contrast resist films. 【0021】 Examples of molecular resists include star-shaped molecules, calixarene derivatives, and dendrimers. Molecular resists have a low molecular size and high uniformity, making them suitable for miniaturization to, for example, 22 nm or less. In addition, molecular resists have a short acid diffusion length, which can reduce the line edge roughness (LER) of the resist pattern. 【0022】 Examples of fluoropolymers include polyfluoroacrylate and polyfluorostyrene. Fluoropolymers have high EUV light absorption, contributing to improved sensitivity of resist films. Furthermore, fluoropolymers exhibit excellent chemical and heat resistance. 【0023】 Furthermore, the resin material may be appropriately designed in terms of deprotection groups (t-BOC, acetoxy groups, etc.), glass transition temperature (Tg), molecular size and uniformity, EUV absorption, developability, etc., in order to achieve the high sensitivity, high resolution, low roughness, and high etching resistance necessary for forming fine patterns. 【0024】The composition for forming the first resist film preferably contains at least one or more metal oxide fine particles, resin materials, and sensitizers. Further, the composition for forming the first resist film may be a so-called hybrid resin in which metal oxide fine particles and sensitizers are dispersed in an organic polymer. 【0025】 The composition for forming the first resist film may contain an organic solvent. The organic solvent is not particularly limited, but in order to disperse the metal oxide fine particles, it is preferably a highly polar organic solvent. Examples of such organic solvents include propylene glycol monomethyl ether acetate (PGMEA), γ-butyrolactone (GBL), N-methylpyrrolidone (NMP), acetone, and isopropyl alcohol (IPA). 【0026】 The contents of the metal oxide fine particles and the sensitizer in the composition for forming the first resist film are not particularly limited and can be appropriately selected according to the composition of the second resist film described later and the relationship with the exposure amount to the resist layer. Specifically, for example, when forming the first resist film, it is preferable to adjust the content of the metal oxide fine particles in the first resist film to be 1 to 50% by mass, and it is preferable to adjust the content of the sensitizer in the first resist film to be 0.1 to 10% by mass. 【0027】 Next, after applying the adjusted composition for forming the first resist film onto the workpiece 10, it is dried to form (film-form) the first resist film 21 on the workpiece 10. 【0028】 The workpiece 10 is not particularly limited, and a semiconductor substrate or the like on which a processed layer such as Si, α-Si, poly-Si, SiO ２ , SiN, SiON, SiGe, GaN, W, TiN, Al, etc. is formed can be used. As the processed layer, Si, SiO ２Examples include Low-k films such as SiON, SiN, poly-Si, α-Si, W, W-Si, Al, Cu, and Al-Si, as well as their stopper films. The processed layer may also be a planarization layer (SOC: Spin On Coating). The film thickness of the processed layer is generally in the range of 50 to 10,000 nm, and particularly preferably in the range of 100 to 5,000 nm. When the processed layer is provided on a semiconductor substrate, it is preferable that the semiconductor substrate and the processed layer be made of different materials. 【0029】 The method for applying the first resist film-forming composition onto the workpiece 10 is not particularly limited, and wet film formation methods such as spin coating, dip coating, inkjet, and spray coating may be used. Among these film formation methods, spin coating is preferred because it allows for easy control of film thickness and enables highly uniform film formation. 【0030】 The thickness of the first resist film 21 is not particularly limited and can be, for example, 5 to 100 nm, but is preferably 10 to 40 nm from the viewpoint of adhesion to the workpiece 10 and pattern formation. 【0031】 The drying method for the first resist film forming composition is not particularly limited, and for example, a bake treatment may be used. Furthermore, as the bake treatment, it is preferable to employ a downward bake method or the like from the viewpoint of preventing distortion of the film due to rapid solvent evaporation. Through these steps, the first resist film 21 is formed on the workpiece 10. 【0032】 After forming the first resist film 21, and before forming the second resist film, at least one of the following treatments—phototherapy, thermal therapy, and chemical therapy—may be applied to the first resist film 21. This treatment generates secondary electrons, a type of active species, in the first resist film 21. As a result, the reactivity of the first resist film 21 when irradiated with EUV light is improved. 【0033】(Second Step) The second step involves forming a second resist film 22 on the first resist film 21, as shown in Figure 2. Specifically, first, a composition for forming the second resist film 22 is prepared. The composition for forming the second resist film includes at least one element from the group consisting of organometallic structures. 【0034】 In this specification, "organometallic structure" means a structure consisting of a metal oxide cluster and an organic ligand, and includes materials generally referred to as metal oxide resist (MOR). 【0035】 A metal oxide cluster (MOR) is a structure in which several to a dozen or so metal atoms (M) and oxygen atoms are bonded at the molecular level. Specifically, metal oxide clusters are molecular structures with a size of about 1 to 2 nm and possess a clear chemical formula and structure. Metal oxide clusters bind to organic ligands to form MORs. When MORs are used as EUV resists, the areas irradiated with EUV undergo a structural change and become insoluble after exposure, resulting in a negative-type resist. 【0036】 Examples of metal elements M include Sn, Zn, Hf, Zr, Sb, Ti, In, Bi, Al, Fe, Ni, Co, Cr, and Mg, which can be used individually or in combination of two or more. The metal oxide clusters containing these metal elements M are not particularly limited, and conventionally applied known clusters can be used. Among these, as metal oxide clusters, from the viewpoint of absorption to EUV light and etching resistance, for example, Sn ６ O ４ (OH) ４ , Hf ６ O ４ (OH) ４ , Zr ６ O ４ (OH) ４ Ti ６ O ４ (OH) ４ Sb ６ O ４ (OH) ４ In６ O ４ (OH) ４ The following are preferred, Sn ６ O ４ (OH) ４ , Hf ６ O ４ (OH) ４ , Zr ６ O ４ (OH) ４ This is preferable. 【0037】 Organic ligands stabilize metal oxide clusters by polydentate coordination, thereby improving their dispersibility. Furthermore, organic ligands decompose and desorb upon EUV light irradiation, rendering the resulting metal oxides insoluble. In other words, organic ligands used in MOR for EUV lithography not only stabilize the structure by binding to metal oxide clusters but also significantly influence reactivity and pattern formation during exposure. 【0038】 The organic ligand is not particularly limited, and conventionally known ligands can be used. Examples of organic ligands include carboxylic acid ligands such as terephthalic acid (BDC: benzene-1,4-dicarboxylic acid) and trimesoic acid (BTC: benzene-1,3,5-tricarboxylic acid), hydroxamic acid ligands such as benzohydroxamic acid, imidazole ligands such as 2-methylimidazole, pyridine ligands such as 4,4'-bipyridine (bpy) and terpyridine (tpy), and amino acid derivatives such as glycine and alanine. 【0039】 The organometallic structure is not particularly limited, and known structures that have been conventionally applied as MORs can be used. Examples of organometallic structures include Zr ６ O ４ (OH) ４ (BDC) ６ , Hf ６ O ４ (OH) ４ (BTC) ６ Sn ６ O ４ (OH) ４ (RCOO)６ These are some examples. 【0040】 In the semiconductor device manufacturing method according to this embodiment, it is preferable to select the metal oxide fine particles used in the first resist film forming composition and the organometallic structure used in the second resist film forming composition so that the first resist film 21 and the second resist film 22 can be developed simultaneously using the same developer. For example, SnO ２ and Sn ６ O ４ (OH) ４ (RCOO) ６ , HfO ２ and Hf ６ O ４ (OH) ４ (BTC) ６ , ZrO ２ and Zr ６ O ４ (OH) ４ (BDC) ６ For example, by using a combination of metal oxide nanoparticles with the same metal element as the core and an organometallic structure, consistency in chemical reactivity during development is ensured, and the difference in interface selectivity between the lower layer, the first resist film 21, and the upper layer, the second resist film 22, is minimized. As a result, the collapse of the pattern shape and the deterioration of LWR (Line Width Roughness) can be suppressed. 【0041】 Furthermore, it is preferable that the sensitivity to EUV light of the metal oxide nanoparticles used in the first resist film forming composition is equal to or greater than that of the organometallic structure used in the second resist film forming composition. An example of such a combination of metal oxide nanoparticles and organometallic structure is a combination in which surface carboxylic acid-modified metal oxide nanoparticles are used in the first resist film. As illustrated, by arranging metal nanoparticles that can exchange sensitizers and ligands in the first resist film 21, which is the underlying film, the sensitivity of the underlying film, which is difficult for EUV light to reach, can be compensated for. 【0042】The second resist film-forming composition may contain an organic solvent for dispersing the organometallic structure. The organic solvent is not particularly limited, and conventionally used known organic solvents can be used. Examples of such organic solvents include propylene glycol monomethyl ether acetate (PGMEA), γ-butyrolactone (GBL), cyclohexane, N-methylpyrrolidone (NMP), and dimethyl sulfoxide (DMSO). 【0043】 The second resist film forming composition may contain, as an organometallic structure, one or more selected from the group consisting of the metal oxide cluster described above, hydrolysates, condensates, and hydrolysis condensates of the metal oxide cluster. By including one or more of these in the second resist film forming composition, the resolution and sensitivity of the second resist film 22 in EUV lithography can be improved. 【0044】 Hydrolyzates of metal oxide clusters are metal alkoxides (e.g., Hf(OR)) ４ , Zr(OR) ４ The precursors, such as ), react with water and undergo hydrolysis. The hydrolyzed product has some M-OH groups formed and is not yet completely condensed. Because the hydrolyzed product is easily stable in solution, it exhibits excellent film formation properties by spin coating. Furthermore, the hydrolyzed product undergoes crosslinking and dehydration condensation upon EUV irradiation, forming a resist pattern. 【0045】 Metal oxide cluster condensates are formed when hydrolyzed M-OH groups undergo dehydration condensation to form M-O-M bonds. These condensates have a higher molecular weight and partially possess a network structure. They exhibit a certain degree of structural stability even before EUV irradiation. Furthermore, they show minimal shrinkage after firing or exposure, resulting in high dimensional stability. 【0046】Hydrolytic condensation products of metal oxide clusters are intermediates or final products resulting from the continuous progression of hydrolysis and condensation. These hydrolytic condensates exhibit a highly developed cluster structure, closely resembling nano-sized metal oxide particles. UV irradiation further crosslinking and decomposition reactions occur within the hydrolytic condensates, forming a resist pattern. The inclusion of hydrolytic condensates in the second resist film-forming composition enables both high EUV absorption and high resolution. 【0047】 Next, the prepared second resist film forming composition is applied onto the first resist film 21, and then dried to form (deposit) the second resist film 22 on the first resist film 21. 【0048】 The method for applying the composition for forming the second resist film onto the first resist film 21 is not particularly limited, as long as it allows for easy control of the film thickness and enables highly uniform film formation. Such an application method preferably involves a wet film formation method, similar to the first step described above, and more preferably a spin coating method. 【0049】 The thickness of the second resist film 22 is not particularly limited and can be, for example, 5 to 100 nm, but is preferably 10 to 40 nm from the viewpoint of pattern formation and durability. It is preferable that the second resist film 22 be formed to be thicker than the first resist film 21. 【0050】 The drying method for the composition for forming the second resist film is not particularly limited, and for example, a bake treatment similar to the first step can be performed. These steps form the second resist film 22 on the first resist film 21. In other words, a resist layer 20 is formed comprising the first resist film 21 provided on the workpiece 10 and the second resist film 22 provided on the first resist film 21. Here, in the resist layer 20, the first resist film 21 contains metal oxide fine particles and a sensitizer, and the second resist film 22 contains at least one of the group consisting of an organometallic structure composed of a metal oxide cluster and an organic ligand. 【0051】(Third Step) In the third step, as shown in Figure 3, the resist layer 20, which is formed by laminating the first resist film 21 and the second resist film 22 on the workpiece 10, is irradiated (exposed) with EUV light. Specifically, the resist layer 20 is exposed to a desired pattern in the direction from the second resist film 22 toward the first resist film 21 (i.e., in the thickness direction of the resist layer 20), either through a predetermined mask or directly. The irradiation amount (exposure amount) is adjusted as appropriate to be suitable for the formed resist layer 20. 【0052】 In the second resist film 22 of the resist layer 20, EUV light irradiation causes the light energy absorbed by the metal oxide clusters to emit photoelectrons. These photoelectrons act on organic ligands bound to the surface of the metal oxide clusters, promoting the decomposition reaction of the organic ligands. 【0053】 This decomposition reaction proceeds primarily through radical reactions or electron transfer reactions, altering the chemical structure of organic ligands in the EUV light-irradiated region (exposure region). This changes the solubility of the resist in the exposure region in the developer, allowing for selective removal or retention. 【0054】 Furthermore, in the first resist film 21 of the resist layer 20, EUV light irradiation causes the light energy absorbed by the metal oxide nanoparticles to emit photoelectrons. When these photoelectrons collide with other molecules, even lower-energy secondary electrons are generated. These break chemical bonds in the resin material and promote decomposition. As a result, the solubility of the resist in the exposed area in the developer changes, allowing for selective removal or retention. 【0055】 After exposure and before development, a post-exposure bake (PEB) may be performed. This bake can accelerate chemical reactions within the resist. As a result, differences in solubility during development become clearer, enabling the formation of fine patterns. There are no particular limitations on the baking process, but for example, it can be performed using a hot plate (contact heating) or an oven (non-contact heating) at a temperature of 90 to 130°C for 30 seconds to several minutes. 【0056】(Fourth step) In the fourth step, as shown in Figure 4, the resist layer is developed to form a resist pattern 20A. Specifically, by developing the exposed resist layer 20 with a developer solution, the unexposed portions dissolve, and a negative-type pattern (resist pattern 20A) consisting of insoluble portions 21A and 22A is formed on the workpiece 10. 【0057】 The development method is not particularly limited, and conventionally applied known methods such as the dipping method, paddle method, and spray method can be used. 【0058】 The developer is not particularly limited, but for example, known developers that have been conventionally used for metal oxide resists can be used. Specifically, it consists of an alkaline developer, an organic solvent-based developer, a buffer solution, or a weakly alkaline developer, or a combination thereof. 【0059】 As the alkaline developer, an aqueous solution containing tetramethylammonium hydroxide (TMAH) is preferably used. The TMAH concentration is preferably adjusted to a range of 0.1 to 2.5% by mass, taking into consideration the stability of the metal oxide particles. 【0060】 As organic solvent-based developers, polar solvents such as isopropyl alcohol (IPA), methanol, and ethanol are used. These can selectively remove the resist in response to the change in polarity of the organic ligands that decompose after exposure. 【0061】 Neutral or weakly alkaline developers, such as carbonate-based buffers and amine-based buffers, enable selective development while suppressing the aggregation and dissolution of metal oxide particles. This improves the dimensional stability and reproducibility of patterns. 【0062】 The conditions for the development process are not particularly limited, but for example, it can be carried out at room temperature or under heated conditions for a time of approximately 30 to 180 seconds. 【0063】After the development process, it is preferable to rinse with pure water or IPA to remove residue and stabilize the pattern. Through these steps, a resist pattern 20A is formed on the workpiece 10. 【0064】 In this embodiment, the semiconductor device manufacturing method involves forming a resist layer 20 on a workpiece 10 by stacking a first resist film 21 containing a sensitizer and a second resist film 22 made of metal oxide resist (MOR) in that order. As shown in Figure 5, the first resist film 21 located on the side of the resist layer 20 opposite to the EUV light irradiation surface (i.e., the side in contact with the workpiece 10) contains a sensitizer, which improves the absorption efficiency of EUV light and promotes the generation of secondary electrons, which are active species R. As a result, the sensitivity of the first resist film 21 is improved, and the reactivity at the interface with the workpiece 10 is improved. This improves the adhesion between the first resist film 21 and the workpiece 10. Furthermore, the active species R generated in the first resist film 21 improves the reactivity at the interface with the second resist film 22. This improves the shape of the resist pattern 20A. 【0065】 In other words, according to the semiconductor device manufacturing method of this embodiment, the shape of the resist pattern 20A is improved, and the adhesion between the resist pattern 20A and the workpiece 10 is improved, thereby suppressing the occurrence of pattern collapse during development. 【0066】 <Second Embodiment> Next, a method for manufacturing a semiconductor device according to the second embodiment will be described. Figures 6 to 10 are cross-sectional views showing an example of a method for manufacturing a semiconductor device according to the second embodiment. Note that Figure 10 corresponds to Figure 5 in the first embodiment. 【0067】The method for manufacturing a semiconductor device according to the second embodiment includes forming a first resist film containing an organometallic structure and a sensitizer on a workpiece, forming a second resist film containing an organometallic structure on the first resist film, irradiating the resist layer containing the first resist film and the second resist film with EUV light, developing the resist layer, and forming a resist pattern. The method for manufacturing a semiconductor device according to this embodiment includes the same first to fourth steps as in the first embodiment. Herein, the method for manufacturing a semiconductor device according to this embodiment differs from the first embodiment described above in that, in the first step, the composition for forming the first resist film contains an organometallic structure and a sensitizer, but the other components are the same as in the first embodiment, so the explanation of the same steps is omitted. 【0068】 (First step) The first step is to form a first resist film 21' on the workpiece 10, as shown in Figure 6. Specifically, first, a first resist film forming composition is prepared for forming the first resist film 21'. The first resist film forming composition (resist film forming composition) includes at least one of the group consisting of organometallic structures and a sensitizer. 【0069】 As the organometallic structure, at least one of the organometallic structures described in the second resist film forming composition of the first embodiment can be used. 【0070】 As the sensitizer, at least one of the sensitizers described in the first resist film forming composition of the first embodiment can be used. 【0071】 The first resist film-forming composition preferably contains at least one sensitizer that generates radicals or ions that promote chemical reactions. Alternatively, the first resist film-forming composition may contain one or more sensitizers that promote the generation of secondary electrons, and one or more sensitizers that generate radicals or ions that promote chemical reactions. 【0072】The first resist film forming composition may contain an organic solvent for dispersing the organometallic structure. As the organic solvent, at least one of the organic solvents described in the second resist film forming composition of the first embodiment can be used. 【0073】 The first resist film forming composition may contain, as an organometallic structure, one or more selected from the group consisting of the above-mentioned metal oxide cluster, hydrolysates, condensates, and hydrolysis condensates of the metal oxide cluster. 【0074】 Next, the prepared first resist film forming composition is applied to the workpiece 10 and then dried to form (deposit) the first resist film 21' on the workpiece 10. Here, the same conditions as those used when forming the second resist film 22 in the first embodiment can be used for the application method and drying method of the first resist film forming composition. 【0075】 After forming the first resist film 21', and before forming the second resist film, at least one of the following treatments—phototherapy, thermal therapy, and chemical therapy—may be applied to the first resist film 21'. This treatment generates secondary electrons, radical species, and ionic species as active species within the first resist film 21'. As a result, the reactivity of the first resist film 21' when irradiated with EUV light is improved. 【0076】 (Second Step) In the second step, as shown in Figure 7, a second resist film 22 is formed on the first resist film 21'. The same composition for forming the second resist film 22 described in the first embodiment can be used. 【0077】 In this embodiment, it is preferable that the organometallic structure used in the first resist film forming composition and the organometallic structure used in the second resist film forming composition are of the same type. By selecting such a combination, the overlap between the exposure conditions in the third step and the development conditions in the fourth step, as described later, is increased, thereby expanding the process margin. 【0078】The combination of organometallic structures used in the first resist film forming composition and the organometallic structures used in the second resist film forming composition may be selected such that the sensitivity to EUV light of the organometallic structure used in the first resist film forming composition is equal to or greater than that of the organometallic structure used in the second resist film forming composition. By selecting such a combination, even if the thickness of the resist layer 20' increases, the sensitivity of the first resist film 21' remains high, and the pattern shape when the resist pattern is formed is good while ensuring adhesion between the first resist film 21' and the workpiece 10. 【0079】 Next, the prepared second resist film forming composition is applied onto the first resist film 21' and then dried to form (deposit) the second resist film 22 on the first resist film 21'. Here, the same conditions as in the second step of the first embodiment can be used for the application method and drying method of the second resist film forming composition. In this way, a resist layer 20' including the first resist film 21' and the second resist film 22 is formed on the workpiece 10. In other words, a resist layer 20' is formed comprising a first resist film 21' provided on the workpiece 10 and a second resist film 22 provided on the first resist film 21'. The first resist film 21' includes at least one organometallic structure composed of a metal oxide cluster and an organic ligand, and a sensitizer, and the second resist film includes at least one organometallic structure. 【0080】 (Third Step) In the third step, as shown in Figure 8, EUV light is irradiated (exposed) onto the resist layer 20', which is formed by laminating the first resist film 21' and the second resist film 22 on the workpiece 10. Specifically, the desired pattern is exposed to the resist layer 20' either through a predetermined mask or directly, in the direction from the second resist film 22 toward the first resist film 21' (i.e., in the thickness direction of the resist layer 20'). The same exposure conditions as in the first embodiment can be used. 【0081】In the second resist film 22 and the first resist film 21' in the resist layer 20', EUV light irradiation causes the light energy absorbed by the metal oxide clusters to emit photoelectrons. These photoelectrons act on organic ligands bound to the surface of the metal oxide clusters, promoting the decomposition reaction of the organic ligands. 【0082】 This decomposition reaction proceeds primarily through radical reactions or electron transfer reactions, altering the chemical structure of organic ligands in the EUV light-irradiated region (exposure region). This changes the solubility of the resist in the exposure region in the developer, allowing for selective removal or retention. 【0083】 After exposure and before development, a post-exposure bake (PEB) may be performed. The same conditions as in the first embodiment can be used for the bake. 【0084】 (Fourth Step) In the fourth step, as shown in Figure 9, the resist layer is developed to form a resist pattern 20'A. Specifically, by developing the exposed resist layer 20' with a developer solution, the unexposed portions dissolve, and a negative-type pattern (resist pattern 20'A) consisting of insoluble portions 21'A and 22A is formed on the workpiece 10. The same development conditions as in the first embodiment can be used. After development, it is preferable to rinse with pure water or IPA to remove residue and stabilize the pattern. Through these steps, the resist pattern 20'A is formed on the workpiece 10. 【0085】In the semiconductor device manufacturing method according to this embodiment, a resist layer 20' is formed on a workpiece 10 by stacking a first resist film 21' containing metal oxide resist (MOR) and a sensitizer, and a second resist film 22 made of MOR, in that order. As shown in Figure 10, the first resist film 21' located on the side of the resist layer 20' opposite to the EUV light irradiation surface (i.e., the side in contact with the workpiece 10) contains a sensitizer, which improves the absorption efficiency of EUV light and promotes the generation of secondary electrons, radical species, and ionic species as active species R. As a result, the sensitivity of the first resist film 21' is improved, and the reactivity at the interface with the workpiece 10 is improved. This improves the adhesion between the first resist film 21' and the workpiece 10. In addition, the active species R generated in the first resist film 21' improve the reactivity of the first resist film 21'. This improves the shape of the lower part (bottom) of the resist pattern 20'A (shape of the insolubilized portion 21'A). 【0086】 In other words, according to the semiconductor device manufacturing method of the second embodiment, similar to the first embodiment described above, the shape of the resist pattern 20'A is improved, and the adhesion between the resist pattern 20'A and the workpiece 10 is improved, thereby suppressing the occurrence of pattern collapse during development. 【0087】 <Third Embodiment> Next, a method for manufacturing a semiconductor device according to the third embodiment will be described. In the first and second embodiments described above, in the fourth step, a resist pattern is formed by simultaneously developing the first resist film and the second resist film using a single developer. In contrast, the method for manufacturing a semiconductor device according to the third embodiment differs from the embodiments described above in that the metal oxide fine particles contained in the first resist film, or the organometallic structure contained in the first resist film and the organometallic structure contained in the second resist film are selected so that the developer for the first resist film and the developer for the second resist film are different, and the first resist film and the second resist film are developed sequentially (separately). 【0088】 In the semiconductor device manufacturing method according to the third embodiment, in the fourth step, the first resist film is developed after the second resist film has been developed. 【0089】Furthermore, in this embodiment, only the second resist film may be developed in the fourth step. This makes it possible to form a resist pattern consisting only of the second resist film on the first resist film. A resist pattern consisting of the second resist film is useful, for example, for use as a metal mask. 【0090】 <Fourth Embodiment> Next, a method for manufacturing a semiconductor device according to the fourth embodiment will be described. In the first and second embodiments described above, a configuration is used to form two resist layers by stacking a first resist film and a second resist film (see Figures 2 and 7). In contrast, the method for manufacturing a semiconductor device according to the fourth embodiment differs from the embodiments described above in that it forms three or more resist layers, with one or more intermediate resist films provided between the first resist film and the second resist film. 【0091】 In the fourth embodiment, it is preferable that one or more intermediate resist films provided between the first resist film and the second resist film contain metal oxide fine particles and a sensitizer, or an organometallic structure and a sensitizer. Furthermore, it is preferable that the amount of sensitizer contained in the first resist film is greater than the amount of sensitizer contained in the one or more intermediate resist films, and that the amount of sensitizer contained in the intermediate resist films decreases from the first resist film 21 side to the second resist film 22 side. 【0092】 According to the semiconductor device manufacturing method of the fourth embodiment, among the three or more resist layers, the first resist film 21 contributes to improving the shape of the lower part (bottom) of the resist pattern, and one or more intermediate resist films contribute to improving the shape of the intermediate part (body) of the resist pattern. As a result, a thick resist pattern can be formed that has excellent adhesion to the workpiece 10 and excellent pattern shape. 【0093】 <Fifth Embodiment> Next, a method for manufacturing a semiconductor device according to the fifth embodiment will be described. The method for manufacturing a semiconductor device according to this embodiment involves processing a workpiece using the formed resist pattern. That is, in addition to the fourth step in the first to fourth embodiments, a step of processing the workpiece (fifth step) may be further included. 【0094】(Step 5) Step 5 involves using the resist pattern formed on the workpiece as a mask to form a predetermined pattern on the workpiece. The pattern formation on the workpiece is not particularly limited and may be carried out by a wet process or a dry process. 【0095】 According to the semiconductor device manufacturing method of the fifth embodiment, when patterning the workpiece, it is possible to form a fine pattern without causing the resist pattern to collapse. 【0096】 10...workpiece 20, 20'...resist layer 20A, 20'A...resist pattern 21, 21'...first resist film 21A, 21'A...insolubilized portion 22...second resist film 22A...insolubilized portion R...active species

Claims

1. A resist film forming composition comprising at least one organometallic structure composed of a metal oxide cluster and an organic ligand, and a sensitizer.

2. The resist film forming composition according to claim 1, wherein the metal element in the metal oxide cluster is one of the group consisting of Sn, Zn, Hf, Zr, Sb, Ti, In, Bi, Al, Fe, Ni, Co, Cr, and Mg.

3. A resist layer comprising a first resist film provided on a workpiece and a second resist film provided on the first resist film, wherein the first resist film contains metal oxide fine particles and a sensitizer, and the second resist film contains at least one of the group consisting of an organometallic structure composed of a metal oxide cluster and an organic ligand.

4. A resist layer comprising a first resist film provided on a workpiece, and a second resist film provided on the first resist film, wherein the first resist film includes at least one organometallic structure composed of a metal oxide cluster and an organic ligand, and a sensitizer, and the second resist film includes at least one organometallic structure.

5. A method for manufacturing a semiconductor device, comprising: forming a first resist film containing metal oxide fine particles and a sensitizer on a workpiece; forming a second resist film on the first resist film containing at least one organometallic structure composed of a metal oxide cluster and an organic ligand; irradiating a resist layer containing the first resist film and the second resist film with EUV light; and developing the resist layer to form a resist pattern.

6. A method for manufacturing a semiconductor device, comprising: forming a first resist film on a workpiece, comprising at least one organometallic structure composed of a metal oxide cluster and an organic ligand, and a sensitizer; forming a second resist film on the first resist film, comprising at least one organometallic structure; irradiating a resist layer comprising the first resist film and the second resist film with EUV light; and developing the resist layer to form a resist pattern.

7. The method for manufacturing a semiconductor device according to claim 6, wherein the second resist film is formed using the same type of organometallic structure as the one used to form the first resist film.

8. The method for manufacturing a semiconductor device according to claim 5 or 6, wherein, after forming the first resist film and before forming the second resist film, at least one of the following treatments is applied to the first resist film: light, heat, and chemical treatment.

9. The method for manufacturing a semiconductor device according to claim 5 or 6, wherein the first resist film and the second resist film are developed simultaneously when developing the resist layer.

10. The method for manufacturing a semiconductor device according to claim 5 or 6, wherein when developing the resist layer, the first resist film is developed first, and then the second resist film is developed.

11. The method for manufacturing a semiconductor device according to claim 5, wherein the metal element in the metal oxide fine particles is one of the group consisting of Sn, Zn, Hf, Zr, Sb, Ti, In, Bi, Al, Fe, Ni, Co, Cr, and Mg.

12. The method for manufacturing a semiconductor device according to claim 5 or 6, wherein one of the group consisting of Sn, Zn, Hf, Zr, Sb, Ti, In, Bi, Al, Fe, Ni, Co, Cr, and Mg is used as the metal element in the metal oxide cluster.

13. The method for manufacturing a semiconductor device according to claim 5 or 6, wherein the organometallic structure is one or more organometallic structures selected from the group consisting of hydrolysates of metal oxide clusters, condensates of metal oxide clusters, and hydrolysates of metal oxide clusters.

14. A method for manufacturing a semiconductor device according to claim 5 or 6, further comprising processing a workpiece using the formed resist pattern.

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