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Water-soluble material, chemically amplified resist and pattern formation method using the sameRelated Patent Categories: Radiation Imagery Chemistry: Process, Composition, Or Product Thereof, Imaging Affecting Physical Property Of Radiation Sensitive Material, Or Producing Nonplanar Or Printing Surface - Process, Composition, Or Product, Radiation Sensitive Composition Or Product Or Process Of MakingWater-soluble material, chemically amplified resist and pattern formation method using the same description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20070082292, Water-soluble material, chemically amplified resist and pattern formation method using the same. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims priority under 35 U.S.C. .sctn.119 on Patent Application No. 2003-425071 filed in Japan on Dec. 22, 2003, the entire contents of which are hereby incorporated by reference. BACKGROUND OF THE INVENTION [0002] The present invention relates to a water-soluble material, a chemically amplified resist and a pattern formation method using the same for use in pattern formation in fabrication process or the like for semiconductor devices. [0003] In accordance with the increased degree of integration of semiconductor integrated circuits and downsizing of semiconductor devices, there are increasing demands for higher performance of lithography technique. In particular, in order to refine patterns, a chemically amplified resist is currently used as a resist material. In the chemically amplified resist, an acid is generated from an acid generator included therein through exposure and post exposure bake, so as to cause a reaction of the resist by using the generated acid as a catalyst. Thus, the resolution and the sensitivity in the exposure are improved. [0004] Now, a conventional pattern formation method will be described with reference to FIGS. 7A through 7D. [0005] First, a positive chemically amplified resist material having the following composition is prepared: TABLE-US-00001 Base polymer: poly((t-butyloxycarbonylmethyloxystyrene) 2 g (65 mol %)-(hydroxystyrene) (35 mol %)) Acid generator: triphenylsulfonium nonaflate 0.05 g Solvent: propylene glycol monomethyl ether acetate 18 g [0006] Next, as shown in FIG. 7A, the aforementioned chemically amplified resist material is applied on a substrate 1 so as to form a resist film 2 with a thickness of 0.4 .mu.m . [0007] Then, as shown in FIG. 7B, pattern exposure is carried out by irradiating the resist film 2 with exposing light 3 of KrF excimer laser with NA of 0.68 through a mask 4. [0008] After the pattern exposure, as shown in FIG. 7C, the resist film 2 is baked with a hot plate at a temperature of 105.degree. C. for 60 seconds (post exposure bake). [0009] Next, the resultant resist film is developed with a 2.38 wt % tetramethylammonium hydroxide aqueous solution (alkaline developer). In this manner, a resist pattern 2a made of an unexposed portion of the resist film 2 and having a line width of 0.14 .mu.m is formed as shown in FIG. 7D. [0010] As shown in FIG. 7D, however, the resist pattern 2a formed by the conventional pattern formation method has a T-top shaped defective portion designated as an insoluble skin layer 2b on the uppermost portions of the side faces thereof (for example, see O. P. Kishkovich and C. E. Larson, "Amine Control for DUV Lithography: Identifying Hidden Sources", Proc. SPIE, 3999, 699(2000)). [0011] When the resist pattern 2a in such a defective shape is used for etching a target film, the resultant pattern of the target film is also in a defective shape, which disadvantageously lowers the productivity and the yield in the fabrication process for semiconductor devices. [0012] Such an insoluble skin layer in the T-top shape is formed when a positive resist is used, and when a negative resist is used, pattern failure derived from reduction in the film thickness occurs. SUMMARY OF THE INVENTION [0013] In consideration of the aforementioned conventional problem, an object of the invention is forming a fine resist pattern in a good shape without forming an insoluble skin layer in development. [0014] The present inventors have made various examinations to find the reason why an insoluble skin layer is formed in a chemically amplified resist during development, resulting in reaching the following conclusion: In general, an acid generator included in a chemically amplified resist does not have high solubility in a solvent, that is, the resist in this case, and hence, it is difficult to dissolve a sufficient amount of acid generator in the resist. Therefore, the amount of an acid generated through the exposure and the post exposure bake tends to be insufficient. Furthermore, when the acid generated in the exposure in an upper portion of the resist film is neutralized and deactivated by an impurity, such as ammonia, included in the atmosphere, the acid cannot be obtained in a sufficient amount for the development. Also, in the case where the amount of acid generator included in the resist material is originally insufficient, the resolution of the pattern is further lowered, resulting in forming an insoluble skin layer. [0015] Accordingly, the present inventors have found the following: When a water-soluble film including a compound constructing an inclusion compound capable of incorporating an acid generator is formed on a resist film made of a chemically amplified resist or when the compound constructing an inclusion compound is included in a resist material itself, the reduced amount of the acid deactivated in the upper portion of the resist film is compensated, so as to prevent the formation of an insoluble skin layer. [0016] The compound constructing an inclusion compound incorporates a hydrophobic compound to make it dissolve in an aqueous solution. The compound constructing an inclusion compound is a compound having a cavity mainly in the center thereof and having a cylindrical shape with a trapezoidal cross-section (bucket shape), and a hydrophilic group is coordinated in an outer portion thereof and a hydrophobic group is included in an inner portion thereof. In other words, the compound constructing an inclusion compound exhibits different properties between its outer portion and its inner portion. Therefore, when the compound constructing an inclusion compound is included in a water-soluble film formed on a resist film or in a resist film itself, an acid generator, which is generally difficult to dissolve in an aqueous solution, is incorporated into the inclusion compound and hence can be stably included in the water-soluble film or the resist film. Specifically, the acid generator and the hydrophobic group present in the inner portion of the inclusion compound are interacted with each other, and hence, the acid generator is incorporated into the inner portion of the inclusion compound. The hydrophilic group present in the outer portion of the inclusion compound is interacted with a water-soluble film component or a resist component, and thus, a large amount of acid generator can be dissolved in the water-soluble material or the resist. When the water-soluble film including the compound constructing the inclusion compound for incorporating the acid generator is formed on a chemically amplified resist film in this manner and the pattern exposure is performed through the resultant water-soluble film, a large amount of acid is generated from the water-soluble film formed on the resist film. This is because the acid generator incorporated in the inclusion compound generates the acid through irradiation with exposing light, and the generated acid is diffused within the resist film from the upper portion thereof. Alternatively, when the inclusion compound for incorporating the acid generator is included in the resist film itself and the pattern exposure is performed, a large amount of acid is generated in an exposed portion of the resist film. This is because not only an acid generator originally included in the resist film but also the acid generator incorporated in the inclusion compound generate the acid through irradiation with exposing light. As a result, even when the generated acid is deactivated to some extent due to the influence of an impurity included in the atmosphere, the acid necessary for resolution can be sufficiently kept in the resist film owing to the acid generated from the inclusion compound. Thus, the formation of an insoluble skin layer can be prevented, resulting in forming a fine pattern in a good shape. Since the inclusion compound is composed of entangled linear polymers and hence minimally has carbon multiple bonds such as an aromatic ring, even when the acid generator is incorporated therein, sufficient exposure for generating the acid can be attained. [0017] The present invention was devised on the basis of the aforementioned findings, and according to the present invention, the formation of an insoluble skin layer formed in the upper portion of a resist pattern is prevented by adding a compound constructing an inclusion compound capable of incorporating an acid generator to a resist film or a water-soluble film formed on a resist film. Specifically, the invention is practiced as follows: [0018] The water-soluble material of the invention is used for forming a water-soluble film on a chemically amplified resist film and includes a water-soluble polymer; an acid generator; a surface active agent; and an inclusion compound for incorporating the acid generator. [0019] When pattern exposure is performed with the water-soluble film made of the water-soluble material of the invention formed on a chemically amplified resist film, a large amount of acid is generated from the inclusion compound incorporating the acid generator in the water-soluble film. The generated acid is uniformly dispersed from an upper portion of the chemically amplified resist film, and therefore, even when the acid generated in the upper portion of the resist film is deactivated due to the influence of an impurity included in the atmosphere, the amount of acid is sufficient for resolution, and hence, formation of an insoluble skin layer can be prevented. As a result, a fine resist pattern can be formed in a good shape. [0020] The chemically amplified resist of this invention includes an acid generator; and an inclusion compound for incorporating the acid generator. [0021] In the chemically amplified resist of this invention, a large amount of acid is generated in pattern exposure from the inclusion compound incorporating the acid generator. Therefore, even when the acid generated in an upper portion of the resist film is deactivated due to the influence of an impurity included in the atmosphere, the amount of acid is sufficient for resolution, and hence, formation of an insoluble skin layer can be prevented. As a result, a fine resist pattern can be formed in a good shape. Continue reading about Water-soluble material, chemically amplified resist and pattern formation method using the same... Full patent description for Water-soluble material, chemically amplified resist and pattern formation method using the same Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Water-soluble material, chemically amplified resist and pattern formation method using the same patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. 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