KR100208321B1 - Pattern forming method - Google Patents

Abstract

As a pattern formation method which can easily form a resist pattern having a good cross-sectional shape, a resist film containing an acid generator is formed on a coated glass film or a silicone resin film to perform radiation irradiation such as sulfur to form a resist pattern. In order to prevent uneven distribution of acid in the resist film generated due to the coated glass film or silicone resin film, an acid generator or an acid generator is added to the coated glass or silicone resin film in advance. The organic polymer film containing is used to suppress the nonuniformity of the acid distribution in the resist film.

By using such a pattern formation method, the defect of the cross-sectional shape of the resist pattern which arises due to the nonuniformity of an acid distribution is prevented, and the resist pattern which is spherical in cross-sectional shape is formed.

Description

Pattern Formation Method

1 (a) and 1 (b) are diagrams for explaining the principles of the present invention.

2 (a) and 2 (b) are diagrams for explaining a phenomenon in which the cross-sectional shape of the resist pattern becomes poor.

3 (a) and 3 (b) show Embodiment 1 of the present invention.

4 (a) and 4 (b) show a second embodiment of the present invention.

5 (a) and 5 (b) show a third embodiment of the present invention.

6 (a) and 6 (b) show a fourth embodiment of the present invention.

7 (a) and 7 (b) show a fifth embodiment of the present invention.

8 shows a general structure of an application glass.

The present invention relates to a pattern forming method, and more particularly, to a pattern forming method capable of easily forming a resist pattern having a good cross-sectional shape.

High density density of ULSI (Ultra Large Scale Integrated Circuit) is progressing four times every three years, and mass production of 4Mbit DRAM and trial production of 16Mbit DRAM are already being carried out. The minimum dimension required for the production of these ULSI is gradually getting finer to 0.8 µm to 0.5 µm, and further to 0.5 µm or less. In order to cope with such a tendency of miniaturization, the examination which improves the resolution in various lithographic techniques is advanced.

In photolithography, which is the mainstream of current lithography, a pattern formation method using light having a wavelength shorter than that used in mass production has been examined to improve resolution. However, when the wavelength of light is shortened, absorption of light in the resist film increases, so that the shape of the pattern tends to be lowered. In order to solve this problem, a high light transmittance resist material is required. In addition, in the electron beam lithography for the next generation, a highly sensitive resist material is desired to improve productivity.

Recently, see, eg, J. Vac. Sci. Technol. B6 (1), Jan / Feb'88, pp319-322, Nano lithography with an acid catalyzed resist and winter solstice pp 379-383, Characterization of a high-resolution novolak based As disclosed in the negative electron-beam resist with 4 μC / cm ² sensitivity, new high-performance resist materials using chemical amplification reactions, or catalysis, are attracting attention.

The resist material using this chemical amplification reaction includes a material that generates a substance that is catalyzed by the irradiation of energy rays, and the intermediate material generated by the irradiation of energy rays is used for the reaction of the resist during processing such as heat treatment. It is characterized by being a catalyst that the reaction proceeds efficiently. For this reason, the transmittance | permeability and a sensitivity can be made high compared with the conventional resist material.

However, the chemically-amplified resist is coated with a glass (dopoglass is generally referred to a compound having a siloxane structure as shown in Fig. 8. Here, Z1 and Z2 are alkyl, alkoxy and acetoxy groups, respectively). And n is the average condensation number of the coated glass), and when the resist pattern is formed by performing exposure and development normally, an abnormality occurs in the resist pattern cross-sectional shape. It became clear by the experiment of this inventor. This abnormality in the shape of the cross section of the resist film is considered to occur because the catalyst material in the resist material decreases in the vicinity of the following film and a nonuniform distribution of the catalyst material occurs in the thickness direction of the resist film. In particular, in the negative resist in which the portion irradiated with the energy ray remains after development, abnormal corrosion occurs in the bottom portion of the pattern, which leads to breakage or peeling of the resist pattern, which is an important problem that must be solved. This phenomenon will be described in more detail with reference to FIG.

By a three-layer resist method using an antireflection film 204 made of an organic compound as a lower layer, a coated glass film 203 as an intermediate layer, and a chemical amplification resist film 202 of a negative type as an upper layer, respectively, for example. In the case of forming a resist pattern, a catalyst material 205 is formed in the portion irradiated with the energy ray 201, and an ugly pattern of the pattern is formed. However, since the catalytic material 205 in the resist film 202 is reduced by the coated glass film 203, the portion 206 without the catalyst material 205 in the resist film 202 is generated. Therefore, the distribution state of the catalyst material 205 in the resist film 202 becomes nonuniform as shown in FIG. Since the catalyst material 205 functions to promote the crosslinking reaction, the crosslinking reaction does not occur in the portion where the catalyst material 205 is not present, and therefore, as shown in FIG. The cross-sectional shape of 202 becomes strange. For this reason, the kind of flooring material which can be processed into a predetermined shape using a chemical amplification resist becomes remarkably narrow, and it becomes difficult to use this resist for ULSI manufacture.

SUMMARY OF THE INVENTION An object of the present invention is to provide a pattern forming method which can prevent such an abnormal occurrence of a pattern cross section and can form a desired pattern using the resist material.

The above object is to include a catalyst generating agent in the coating glass to form the resist film thereon or to under the coating glass when the resist material using a chemical amplification (catalyst) reaction is adapted to photolithography. This is achieved by disposing a film containing a generator of. Generally, an acid is used as this catalyst and an acid generator is used as a catalyst generating agent in many cases. In the following description, the material of this acid catalyst is used.

As shown in FIG. 1A, an organic compound film 4 containing an acid generator, a coated glass film 3, and a chemically amplified resist film 2 are formed on the substrate 7 so as to overlap each other. When the line 1 is irradiated to a predetermined region, an acid 5 is generated in the resist film 2. However, since the energy ray 1 passes through the coating-type glass film 3 and reaches the organic compound film 4, an acid 6 is generated in the organic compound film 4 as well. In the resist film 2, the acid 5 is unevenly distributed as described above, so that a portion free of acid 5 occurs. However, the acid 6 generated in the organic compound film 4 is coated with a glass film. (3) diffuses into the resist film 2, and the diffused acid 6 compensates for the deficiency of the acid 5 in the resist film 2, so that the concentration distribution of the acid 5 is uniform. Done. As a result, as shown in Fig. 1B, a resist pattern 2 having a good cross-sectional shape is formed.

By arranging the organic compound layer containing an acid generator as described above under the coating glass film, it was confirmed that the cross-sectional shape of the resist pattern can be normally performed.

Moreover, as an acid generator, a halogen compound etc. which have a oni salt, a sulfonic acid ester, a triazine ring, etc. can be used, for example.

Example 1

In Example 1, a novolak resin film having a benzene ring, which is an organic resin having an optical absorption coefficient of about 1 μm ⁻¹ , formed by adding 5% of a photoacid generator to a solution was used as an underlayer film (antireflection film) of a three-layer resist. to be.

As shown in Fig. 3 (a), a novolak resin film 304 having the above Banshee ring having a thickness of 1.6 mu m is formed on the substrate 307 by a normal coating method, and a hot plate baking apparatus The novolak resin film 304 was insolubilized by baking at 230 DEG C for 6 minutes. Subsequently, a coated glass film 303 was formed thereon, and baked at 230 ° C. for 6 minutes to densify the coated glass film 303. After performing the adhesion improving treatment, a chemical amplifying agent negative type photoresist THMR-iN 100 (Tokyo Industries Co., Ltd.) was applied to form a photoresist film 302, and baked at 90 DEG C for 2 minutes using the baking apparatus. The solvent was volatilized. The light 301 was irradiated using the i-line reduction projection exposure apparatus (NA = 0.42). Next, baking was performed at 110 DEG C for 2 minutes, and developed with a tetramethyl ammonium hydroxide solution having a concentration of 2.38% to form a photoresist pattern 302 as shown in FIG. As a result of observing the cross section of the photoresist pattern 302 with a scanning electron microscope, it was confirmed that a good spherical cross section without any abnormality was formed in the pattern cross section. As described above, the acid 306 generated by light irradiation in the organic resin film 304 enters the photoresist film 302 through the coating glass film 303 and the light irradiation of the photoresist film 302. It is estimated that it was obtained because the nonuniformity of the distribution of the acid 305 in the area was eliminated or relaxed. The light absorption coefficient of the resin film can be used as an antireflection film as long as it is in the range of 0.02 to 2 μm ⁻¹ . However, the range of the light absorption coefficient is more preferably 0.08 to 1.2 µm ^-1 in view of the pattern size accuracy and stability of the pattern.

Example 2

As shown in Fig. 4A, in this embodiment, the chemically amplified resist SAL601 (manufactured by Seaplay Perst) film 402 as the upper layer, the coated glass film 403 and the lower layer film 404 as the intermediate layer. As a resist, a resist THMR-iN100 film was used. After the lower layer film 404 and the coated glass film 403 were formed, baking at 230 ° C. for 6 minutes was performed respectively. Subsequently, the surface of the coated glass film 403 was subjected to hydrophobization treatment, coating, and soft baking at 80 ° C. for 30 minutes, and then light 401 was irradiated to a desired area using an electron beam drawing apparatus with an acceleration voltage of 30 kV. . After performing the bake treatment, it was developed with a tetramethyl ammonium hydroxide (0.27 regulation) solution to form a resist pattern 402 as shown in Fig. 4B. Also in this Example, the resist pattern which has a favorable spherical cross section which has no abnormality in a cross section similarly to Example 1 was obtained.

Example 3

In this embodiment, a film made of a chemical amplifying agent negative type photoresist THNR-iN100 (Tokyo Corporation) was used as an upper layer film in the multilayer resist method, and was also formed under the coated glass film to form a pattern in a four-layer structure. It shows the case of execution.

As shown in Fig. 5 (a), an antireflection film 508 having a thickness of 1.6 mu m made of an organic light absorbing material (Hitachi Kasei trade name: RAYCAST (RB3900B)) is applied to the substrate 507 in a conventional coating method. The resist film was baked and insolubilized for 6 minutes at 230 ° C. in a hot-plate baking apparatus, and then the resist THMR-iN100 was applied to form a resist film 504, which was then baked and insolubilized.

The coated glass was coated thereon to form a coated glass film 503, which was then baked at 230 ° C. for 6 minutes to densify. After the surface of the coated glass film 503 was subjected to hydrophobization treatment, THMR-iN100 was applied to form a second resist film 502. The solvent was volatilized by baking at 90 DEG C for 2 minutes using the baking apparatus. . I-line reduction projection exposure apparatus (NA = 0.42) was used for exposure of the pattern, and it irradiated to the area | region to which i-line 501 is desired. The bake was performed at 110 DEG C for 2 minutes, and then developed with a tetramethyl ammonium hydroxide solution having a concentration of 2.38% to form a resist pattern 502 as shown in FIG. As a result of observing the cross section of the resist pattern 502 with a scanning electron microscope, it was confirmed that there was no abnormality in the cross sectional shape and that a good spherical cross sectional shape was obtained up to a dense pattern.

Example 4

This example is an example in which a resist pattern is formed by using a silicone resin to which an acid generator triphenylsulfonium trifluoromethane sulfonate is added as an intermediate layer in the three-layer resist method.

The acid generator in an amount of 5% is added to the solid content of the glass of the silicone resin solution containing methanol as a main component, and the silicone resin is coated on the silicon substrate 607 with a thickness of 0.1 탆 to form the silicone resin film 603. Formed. 604 denotes an antireflection film formed of an organic material. Subsequently, the solution was baked at a temperature of 200 ° C. for 30 minutes to volatilize the solution from the silicone resin film 603.

After hydrophobizing the surface of the silicone resin film 603, a chemical amplification resist material SAL 601 (manufactured by Seaplay Perst Co.) was applied to a thickness of 0.5 mu m to form a resist film 602, and an electron beam having an acceleration voltage of 30 kV. The pattern was drawn by the electron beam 601 using the drawing apparatus.

Next, after baking at 110 ° C. for 10 minutes, it was developed with a solution of tetramethyl ammonium hydroxide (0.27 regulation), and a resist pattern 602 was formed as shown in FIG. 6 (b).

As a result of observing the cross section of the resist pattern 602 with a scanning electron microscope, it was confirmed that there is no abnormality in the cross sectional shape and a resist pattern having a good spherical cross section is formed. This result is presumed to be obtained because the acid 6 generated in the silicone resin film 703 enters the resist film 702 and eliminates the uneven distribution of the acid 705 generated in the light irradiation region of the resist film 702. .

Example 5

This example is an example in which triphenyl and sulfonium trifluoro metasulfonic acid salts are used as a lower layer of a film made of a material in which 5% of the solid content of the coated glass is added as an acid generator to the coated glass containing titanium oxide. Indicates.

The coated glass material to which the acid generator has been added is applied onto the substrate 704 to form a coated glass film 703, thereon a positive resist film 702 is formed thereon, and the electron beam 701 is irradiated. To form a pattern. As a result, a resist pattern 702 having a good cross-sectional shape was formed as shown in Fig. 7B.

In this embodiment, the acid 706 generated by the irradiation of the electron beam diffuses into the resist film 702, and the uneven distribution of the acid 705 generated in the irradiated region of the resist film 702 by the electron beam irradiation is eliminated or It is assumed that the above effects are obtained by this. Therefore, according to the present embodiment, a positive type of an optical amplification resist resist composed of a novolak resin, a dissolution inhibitor, and an acid generator is formed on a coated glass film of a mixed system of titanium oxide and silicon oxide. When the pattern is processed at, the cross-sectional shape of the resist pattern can be improved by preventing insolubilization of the bottom surface of the resist.

In addition, the present invention is a method of avoiding abnormality in the cross-sectional shape of the chemical amplification resist with a material containing an acid generator, so that the material to which the acid generator can be added is not limited to a coating-type silicone resin or a coated glass. Of course, other materials can be used without it.

As apparent from the above description, according to the present invention, it is possible to prevent abnormality in the cross-sectional shape of the chemically amplified resist pattern caused by any kind of base material without adding any complicated treatment to the conventional multilayer resist process. At this time, the acid type and content of the chemically amplified resist can be appropriately selected in consideration of the combination with the acid contained in the film provided under the resist film.

In addition, in this specification, a method of preventing abnormality in the pattern cross section caused by the loss of acid in the chemical amplification resist has been described. However, abnormality caused by volatilization or diffusion of a substance in the resist film occurs. In this case, the same effect can be obtained by replenishing the lost material with the lower layer material. Therefore, in the manufacture of semiconductor devices such as ULSI and ultrafine devices, which are gradually integrated in the future, chemical amplification using reaction of the catalytic material It is extremely effective because it is possible to effectively use excellent performances such as a resist, and to further promote the integration density of various semiconductor devices.

Claims (13)

Forming a first film on the surface of the substrate, forming a photoresist film on the film, and generating the acid at the light irradiation portion of the photoresist film and the first film. And irradiating light on a film and developing the photoresist film to form a pattern of the photoresist film, wherein the first film and the photoresist film contain an acid generator in which acid is generated by light irradiation. And the solubility of the light irradiating portion of the photoresist film is changed by reaction using an acid as a catalyst, and the acid generated in the light irradiating portion of the first film is diffused into the light irradiating portion of the photoresist film, and the An acid deficiency in the light irradiation part is supplemented by the diffused acid so as to be in the light irradiation part of the photoresist film. The acid concentration distribution of the pattern forming method becomes uniform. The pattern forming method according to claim 1, wherein an antireflection film is interposed between the first film and the substrate. The pattern forming method according to claim 1, wherein a glass film having a siloxane structure is interposed between the first film and the photoresist film. The pattern forming method according to claim 1, wherein a silicon resin film is interposed between the first film and the photoresist film. The pattern forming method according to claim 1, wherein the first film is an organic polymer film containing an acid generator. The pattern forming method according to claim 1, wherein the first film is a film selected from the group consisting of glass having a siloxane structure and a silicone resin. The pattern forming method of claim 1, wherein the acid generator is selected from the group consisting of oni salts, sulfonic acid esters, and halogen compounds having a triazine ring. The method of claim 1, wherein the concentration of the acid generator contained in the photoresist film is substantially the same as the concentration of the acid generator contained in the first film. The method of claim 1, wherein the first film contains 1.25% to 10% of the acid generator. The method of claim 1, wherein the photoresist film is a negative photoresist film. The method of claim 1, wherein the photoresist film is a positive photoresist film. The pattern forming method according to claim 1, wherein the acid generated in the first film by exposure to light is diffused into the photoresist film so that an uneven distribution of acids in the photoresist film is rescued. The pattern forming method of claim 1, wherein the first film is a resist.