JPH0360109B2 - - Google Patents

Description

[Detailed description of the invention]

(1) Technical Field of the Invention The present invention relates to negative resist materials, and more particularly to negative resist materials for recording high energy radiation such as electron beams, X-rays, gamma rays, etc. This resist material can not only be used advantageously in the fabrication of semiconductor devices, but also widely and advantageously used as a photosensitive material due to its excellent properties. The present invention also relates to a resist pattern forming method using the above-described negative resist material. (2) Background of technology As a recent trend, in the field of semiconductor devices, efforts are being focused on the development of microfabrication technology on the submicron order in order to cope with the increasing degree of integration. It has also been found that exposure equipment that utilizes high-energy radiation such as electron beams, X-rays, gamma rays, etc., is useful for achieving such controlled line exposure with dimensions on the order of submicrons. . Furthermore, in this regard, various types of resist materials have been proposed that can fully demonstrate the performance of the exposure apparatus as described above. Photosensitive polymer materials are usually used as resist materials for ease of use, and from a functional standpoint, the main chain of the polymer in the radiation-irradiated area is cut (reduced in molecular weight) to form the easily soluble portion. One is a positive type, which is based on dissolving and removing in a subsequent development process, and the other is a soluble non-irradiated area, in which the insolubilized area is removed by crosslinking (three-dimensional reticulation) between polymer molecules in the radiation irradiated area. It can be classified into negative type, which is based on dissolving and removing. In particular, positive resist materials have high resolution suitable for submicron microfabrication, and are therefore advantageously used in this technical field. (3) Prior art and problems Although conventional negative resist materials for recording high-energy radiation have relatively good sensitivity, they are not always effective in other qualities such as resolution. I can't tolerate it. This is thought to be due to the fact that in conventional negative resist materials, a negative pattern is formed by a crosslinking reaction between polymer molecules. For example, in conventional negative-tone electron beam resist materials, after electron beam exposure, a crosslinking reaction occurs between polymer molecules within the exposed area, and the insolubilized portions ultimately remain as a negative pattern. do. However, since the crosslinking reaction, which is a reaction of functional groups activated by an electron beam, is a type of chain reaction, it has the disadvantage that the contrast obtained is reduced first. . Second, during the chain reaction, some substances that cannot participate in crosslinking remain, and
These have a very long lifespan. These remaining components cause radical movement, leading to deformation of the pattern over time. As a result of such a chain reaction that proceeds as a dark reaction in a vacuum, it is extremely difficult to control the pattern width obtained. Additionally, this type of e-beam resist material is generally susceptible to pattern swelling, which also contributes to reduced contrast and resolution. For the above reasons, it is difficult to use conventional negative resist materials for recording high-energy radiation to form fine patterns. (4) Purpose of the Invention The purpose of the present invention is to provide a method for recording high-energy radiation, which not only has excellent sensitivity but also has resolution, contrast, etc. equivalent to or higher than that of conventional positive resist materials. An object of the present invention is to provide an improved negative resist material useful for. (5) Structure of the Invention In the course of research to achieve the above-mentioned object, the present inventor discovered a method by controlling the solubility of a specific compound in place of the crosslinking reaction, which is the conventional photosensitive mechanism. We have discovered that it can be expected to have excellent effects. In other words, the current discovery is that the irradiated portions have been crosslinked until now, but are initially alkali-soluble, but are converted to alkali-insoluble by irradiation with high-energy radiation. In one aspect, the present invention comprises an alkali-soluble polymeric compound as a host polymer and an alkali-soluble photosensitive compound capable of producing an alkali-insoluble compound as a result of high-energy radiation. and in the molecule of the photosensitive compound, an organic acid component and a second reactive component capable of reacting with the organic acid component to produce an alkali-insoluble compound as a result of high-energy radiation are present together. It is a negative resist material that is characterized by Moreover, in another aspect of the present invention,
It has an alkali-soluble polymer compound as a host polymer and two types of alkali-soluble photosensitive compounds capable of producing an alkali-insoluble compound as a result of high-energy radiation, and among the photosensitive compounds, an organic acid component in the molecule of one compound, and a second reactive component capable of reacting with the organic acid component to produce an alkali-insoluble compound as a result of high-energy radiation, in the molecule of the other compound; The negative resist material is characterized by the presence of each of them. Furthermore, in another aspect of the present invention, an alkali-soluble polymer compound as a host polymer is mixed in a proportion of 5 to 50% by weight with respect to the polymer compound, and the result is high energy radiation. 1 that can produce an alkali-insoluble compound by the reaction of the organic acid component and the second reaction component as
applying a negative resist material having one or two types of alkali-soluble photosensitive compounds to a substrate; and irradiating the negative resist material with a pattern of high-energy radiation to cause the polymer compounds to react. a step of making the irradiated area alkali-insoluble by reacting the photosensitive compound without irradiation; and a step of removing the negative resist material in the area not irradiated with the high-energy radiation with water or an alkaline developer. A method of forming a resist pattern is characterized by the following. In short, the present invention uses an alkali-soluble polymeric compound as a host polymer in combination with a specific alkali-soluble compound whose alkali solubility disappears upon irradiation with high-energy radiation, that is, produces an alkali-insoluble compound. In this case, after irradiation with high-energy radiation, an alkali-insoluble compound is generated in the alkali-soluble polymer compound in the irradiated area, and the two become blended, and the whole becomes insoluble in alkali, and thus, This mechanism is based on the mechanism that only the non-irradiated areas excluding the irradiated areas can be easily dissolved and removed with water or an alkaline developer in the subsequent development process. As used herein, "high energy radiation"
includes various forms of radiation such as electron beams, x-rays, gamma rays, etc., as is generally recognized in the art. Therefore, although the invention will be described below with particular reference to electron beam exposure, it is understood that the invention is also useful for exposure to other forms of high-energy radiation, such as, for example, X-rays. I want to be In the present invention, the only requirement is that the polymer compound used as the host polymer has alkali solubility. Other conditions may not be required except in special cases. Such a polymer compound usually has an alkali-soluble group such as an acid group or a phenol group in its side chain. Examples of polymer compounds useful in the present invention include the following. Phenolic resin: p-vinylphenol resin: Styrene-acrylic acid copolymer: Styrene-methacrylic acid copolymer: Cresol-novolak resin: Methacrylic acid ester-acrylic acid copolymer: R= _C1 - _C5 alkyl Compounds as photosensitizers that can be used together with these polymeric compounds are not particularly limited as long as they meet the essential requirements as described above. . From research conducted by the present inventors, examples of organic acid components include carboxylic acid, sulfonic acid, chromic acid, and phosphoric acid, and second reaction components that can react with these organic acid components include amines and acids. Halides, alcohols, phenols, basic carbonium dyes, imidazole derivatives, epoxy compounds, etc. have been found to be useful. These components may be arbitrarily combined and both components may be contained in the same compound, or
Otherwise, each can be used in separate compounds. Some preferred examples of combinations of the organic acid component and the second reaction component are listed below. A combination in which the acid component and the second reaction component are present in the same compound:

【formula】 【formula】

Combinations in which the acid component and the second reaction component are present in separate compounds:

[Table] These compounds as photosensitizers are generally advantageously used in an amount of about 5 to 50% by weight (total amount), based on the weight of the polymeric compound used at the same time. However, depending on various factors such as the type of polymer used, the processing conditions applied, the desired results, etc., it is also possible to use amounts outside the above ranges. The above-mentioned photosensitizer compound is rendered alkali insoluble or poorly alkali soluble by irradiation with high-energy radiation, and this is thought to proceed, for example, according to the following reaction mechanism. According to the present invention, first, a resist solution is prepared from a negative resist material containing the above-mentioned polymer compound and photosensitizer compound, and this solution is applied as a resist onto the substrate to be etched. Particularly preferred substrates that may be used herein include semiconductor substrates such as silicon wafers, chromed glass, and metals such as aluminum. To prepare the resist solution, the solvents customary in this field can be advantageously used. Preferred examples of useful solvents include methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, acetone, tetrahydrofuran, benzene, toluene, xylene, dimethylformamide, methyl cellosolve acetate, and the like. Mixtures of these solvents can be used if desired. Conventional coating methods are useful for applying the resulting resist solution to the substrate. Preferred coating methods include spin coating, doctor blade coating, dip coating, hopper coating, and others. After the solvent in the applied resist film is completely removed by prebaking according to a conventional method, the resist film is irradiated with an image-like pattern of high-energy radiation. In this way, the radiation-exposed portions can be kept insoluble and the non-irradiated portions can be kept soluble.
The detailed mechanism of insolubilization is as described in detail above. According to the present invention, in the subsequent development step,
The non-irradiated portion, which is kept soluble first, can be developed with water or an alkaline developer to dissolve and remove the portion. As a result, the irradiated portion remains on the substrate as a resist pattern. Alkaline developers useful in the present invention include, for example, aqueous alkali solutions such as potassium hydroxide, sodium hydroxide, and the like. Although higher concentrations of such alkaline aqueous solutions can be used in consideration of shortening development time, etc., it is generally advantageous to have a concentration of 1 to 30%. If necessary, other alkaline developers can be used, such as an organic amine compound commercially available from Shippley under the trade name MF312. (6) Examples of the invention Next, the present invention will be explained with reference to the following examples. Example 1 Styrene-acrylic acid copolymer (copolymerization ratio
8.5:1.5, Mw=4×10 ⁴ ) and 20 parts by weight of o-aminobenzoic acid were dissolved in methyl cellosolve acetate to prepare a 25 wt% resist solution.
This was applied onto a Si wafer with a thickness of 1 μm by spin coating.
Apply thickly. Next, prebaking is performed at 80° C. for 20 minutes, and then a predetermined pattern is exposed to a 20 KeV electron beam. A sensitivity of 1×10 ⁻⁵ C/cm ² was obtained by developing with a 30% aqueous solution of MF312. The pattern did not swell and had good resolution. Example 2 Cresol-novolak resin (Mw=8000) 80
parts by weight and 20 parts by weight of a mixture of p-toluic acid/p-toluic acid chloride = 1/1 (mole ratio).
A 25wt% resist solution was prepared. This was coated onto a Si wafer with a thickness of 8000Å by spin coating.
Apply thickly. Next, the film was prebaked at 60° C. for 20 minutes, and developed with a 50% aqueous MF312 solution exposing a predetermined pattern to a 20 KeV electron beam to obtain a sensitivity of 8×10 ⁻⁶ C/cm ² . The pattern is
There was no swelling and the resolution was good. (7) Effects of the Invention According to the present invention, it is possible not only to obtain the excellent sensitivity inherent to negative resist materials, but also to obtain the excellent sensitivity inherent in negative resist materials.
Since it does not utilize a cross-linking reaction like the conventional one, it is possible to obtain both enhanced resolution and enhanced contrast. Therefore, the negative resist material according to the present invention can be advantageously used for forming fine patterns by exposure to high-energy radiation.

Claims (1)

[Scope of Claims] 1. A host polymer comprising an alkali-soluble polymer compound and one kind of alkali-soluble photosensitive compound capable of producing an alkali-insoluble compound as a result of high-energy radiation, and In the molecule of the photosensitive compound, an organic acid component and a second reactive component capable of reacting with the organic acid component to produce an alkali-insoluble compound as a result of high-energy radiation are present together. Characteristic negative resist material. 2. It has an alkali-soluble polymer compound as a host polymer and two types of alkali-soluble photosensitive compounds capable of producing an alkali-insoluble compound as a result of high-energy radiation, and an organic acid component in the molecule of one of the compounds, and a second reactive component capable of reacting with the organic acid component to form an alkali-insoluble compound as a result of high-energy radiation; A negative resist material characterized by the presence of each of these. 3 A polymer compound having alkali solubility as a host polymer and 5
1, which is mixed in a proportion of ~50% by weight and capable of producing an alkali-insoluble compound by reaction of the organic acid component with the second reactant component as a result of high-energy radiation.
applying a negative resist material having one or two types of alkali-soluble photosensitive compounds to a substrate; and irradiating the negative resist material with a pattern of high-energy radiation to cause the polymer compounds to react. a step of making the irradiated area alkali-insoluble by reacting the photosensitive compound without irradiation; and a step of removing the negative resist material in the area not irradiated with the high-energy radiation with water or an alkaline developer. A resist pattern forming method characterized by comprising: 4. The photosensitive compound is one type of compound, and the molecule contains an organic acid component and a second reactive component capable of reacting with the organic acid component to produce an alkali-insoluble compound as a result of high-energy radiation. 4. The resist pattern forming method according to claim 3, wherein: 5. The photosensitive compound is a mixture of two compounds, and one of the compounds has an organic acid component in its molecules, and the other compound has an organic acid component that reacts with the organic acid component as a result of high-energy radiation. 4. The method for forming a resist pattern according to claim 3, wherein each second reaction component capable of producing an alkali-insoluble compound is present.