JP4613695B2 - Manufacturing method of semiconductor device - Google Patents

Description

  The present invention relates to an organic material manufacturing method and a semiconductor device manufacturing method using the same, and more particularly to a resist material manufacturing method and a semiconductor device manufacturing method.

  Circuit patterns drawn on a mask using photolithography technology when manufacturing various devices such as semiconductor elements such as memories and logic circuits, display elements such as liquid crystal panels, detection elements such as magnetic heads, and imaging elements such as CCDs Conventionally, a reduction projection type exposure apparatus that transfers the image onto a substrate such as a wafer by a projection optical system has been used.

  The minimum pattern size (resolution) that can be transferred by this exposure apparatus is proportional to the exposure light wavelength and inversely proportional to the numerical aperture (NA) of the projection optical system. That is, in order to achieve high resolution, it is preferable to shorten the exposure light wavelength or design a projection optical system having a large NA.

The history of improving resolution has been developed in exactly the same way. The shortening of the exposure light wavelength has shifted from g-line (436 nm) to i-line (365 nm), KrF (248 nm), ArF (193 nm). In the future, F ₂ (157 nm) or EUV (13. Development is progressing toward the realization of 5 nm). In parallel with this, the NA of the projection optical system has been accelerated, and now an exposure apparatus having an NA exceeding 0.9 has been developed and sold.

  As one means of continuing such a miniaturization flow without stagnation, application of immersion exposure using an ArF laser has been attracting attention (see, for example, Patent Document 1).

JP-A-10-319834

  Immersion exposure is a method for realizing higher NA by filling the space between the projection optical system and the wafer substrate with liquid. In other words, the NA of the projection optical system is NA = n sin θ where the refractive index of the liquid is n (n> 1). Therefore, by satisfying a medium having a refractive index n higher than the refractive index of air, the NA is “1”. It is possible to extend the exposure to an area of more than n.

  Here, the immersion exposure method will be specifically described. In the immersion exposure, a resist film is formed on the substrate to be processed, and the substrate in this state is directed to the projection optical system side with water or the like. Soak in the immersion liquid. Next, a mask is disposed above the resist film, and immersion exposure is performed in a state where the immersion liquid is filled between the resist film and the projection optical system.

  An ArF laser is regarded as a promising exposure light for this immersion exposure. This is because an ArF laser that has been used in the past can be used as an exposure light, so that it can be applied to the next generation LSI without significant facility change for semiconductor manufacturing. Cost merit is one of the great attractions.

  However, in the immersion exposure method as described above, components contained in the resist material (organic material) are likely to elute into the immersion liquid from the surface of the resist film applied on the substrate to be processed. For example, when a chemically amplified photoresist is used, a photoacid generator (PAG) in the resin constituting the resist material, a quencher component that controls the diffusion of the generated acid, an additive component such as a surfactant, etc. The resist material composition component is contained. However, when the above components are eluted from the resist film surface into the immersion liquid, the concentration of the above components is lowered on the surface side of the resist film, resulting in a difference in component concentration in the film thickness direction of the resist film. For this reason, when immersion exposure is performed in this state, the resolution on the surface side of the resist film becomes lower than that on the inner side, and the shape of the resist pattern deteriorates and dimensional errors occur. In addition, a trace amount of water also penetrates into the resist film from the immersion liquid, and the resolution deteriorates due to swelling of the resist film, resulting in a resist pattern shape deterioration and dimensional error.

  Further, when a pattern is formed on an organic film such as an antireflection film by etching using the resist pattern, the organic material constituting the organic film has the same problem as described above. In this case, the upper surface side of the organic film is covered with the resist film in the immersion liquid, but the edge side of the organic film may be in contact with the immersion liquid at the edge portion of the substrate (wafer). At this time, since the components contained in the organic film are eluted from the edge side into the immersion liquid, the concentration of the component on the edge side is lowered, resulting in a difference in the component concentration between the edge side and the center side of the organic film. . Therefore, when patterning the organic film, a dimensional error of the pattern occurs between the edge side and the inner side.

  Furthermore, even if the variation in the amount of each component contained in the organic material of different lots is within an allowable range, when an organic film (including a resist film) is formed, the immersion liquid may differ due to a difference in coating film thickness. There is a difference in the amount of elution of the components. For this reason, the variation in the amount of each component in the organic film is amplified between lots, resulting in a variation outside the allowable range. Therefore, for example, when resist patterns having the same shape are formed using resist materials of different lots, it is difficult to keep the pattern dimensional error within an allowable range.

  From the above, there has been a problem that the yield of a semiconductor device manufactured using the above-described resist film or an organic film under the resist film is lowered.

  Accordingly, the present invention provides a method for manufacturing an organic material and a method for manufacturing a semiconductor device that suppress elution of components from a resist film and an organic film under the resist film into the immersion liquid during immersion exposure. It is an object.

  In order to achieve such an object, the method for producing an organic material of the present invention is a method for producing an organic material constituting a resist film exposed by immersion exposure or an organic film provided under the resist film. The following processes are sequentially performed. First, in a 1st process, each component which comprises an organic material is mix | blended, and an organic material is prepared. Next, in the second step, this organic material is mixed with a solvent composed of the same component as the immersion liquid used for immersion exposure and washed to elute some of the components in the organic material into the solvent.

  According to such a method for producing an organic material, the organic material is mixed with a solvent composed of the same component as the immersion liquid and washed, and a part of the component in the organic material is eluted into the solvent, thereby providing an organic material. The elution of the components from the material to the immersion liquid and the penetration of the immersion liquid into the organic material are performed in advance. As a result, even if this organic material is applied onto the substrate to form an organic film, and the substrate in this state is immersed in the immersion liquid, the elution of components from the surface of the organic film into the immersion liquid and the organic Infiltration of immersion liquid into the membrane is suppressed.

The method of manufacturing a semiconductor device according to the present invention is a method for manufacturing a semiconductor device in which immersion exposure is performed after an organic material is applied on a substrate to form an organic film and then the substrate is immersed in an immersion liquid. A manufacturing method characterized by sequentially performing the following steps. First, in the first step, the organic material is mixed with a solvent composed of the same components as the immersion liquid and washed to elute some of the components in the organic material into the solvent. Next, in the second step, the washed organic material is applied onto the substrate to form an organic film. Next, in the third step, immersion exposure is performed in a state where the substrate on which the organic film is formed is immersed in the immersion liquid using the solvent after the organic material is washed in the first step as the immersion liquid. .

  According to such a method for manufacturing a semiconductor device, an organic material is mixed with a solvent composed of the same component as the immersion liquid and washed, and a part of the component in the organic material is eluted in the solvent, thereby organic The elution of the components from the material to the immersion liquid and the penetration of the immersion liquid into the organic material are performed in advance. And after applying this organic material on the substrate to form the organic film, the substrate on which the organic film is formed is immersed in the immersion liquid, so that the components are eluted from the surface of the organic film into the immersion liquid. Further, the penetration of the immersion liquid into the organic film is suppressed.

  As described above, according to the method for producing an organic material of the present invention and the method for producing a semiconductor device using the same, the elution of components from the surface of the organic film into the immersion liquid and the immersion in the organic film The penetration of the liquid is suppressed. Thereby, for example, when the organic film is a resist film, the elution of components from the surface of the resist film is suppressed, so that the concentration of the components on the surface of the resist film is suppressed from decreasing. Therefore, it is possible to prevent a reduction in the resolution of the resist film surface. Moreover, since the penetration of the immersion liquid into the organic film is suppressed, it is possible to prevent a decrease in resolution due to the swelling of the resist film. As described above, the resist pattern shape deterioration and dimensional error can be suppressed, and the yield of the semiconductor device to be manufactured can be improved. In addition, the lot quality uniformity (variation) of materials used in the immersion exposure process can be managed and improved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(First embodiment)
An example of an embodiment of an organic material manufacturing method and a semiconductor device manufacturing method using the same according to the present invention will be described with reference to FIGS. In this embodiment, an example of a method for manufacturing a semiconductor device will be described in the case where a resist material is prepared and cleaned, and immersion exposure is performed on a resist film formed from the cleaned resist material.

  First, as shown in FIG. 1, a resist material 11 is prepared (S101). Here, an example in which a chemically amplified positive resist for ArF exposure is used as the resist material 11 will be described. The resist material 11 is formed by dissolving a resin component made of, for example, a fluorine-containing resin in an organic solvent. Examples of the fluorine-containing resin include monomers obtained by introducing a hydroxyhexafluoroisopropyl group into trifluoromethacrylate and norbornene, and polymers (polymer / oligomer) thereof.

  The resist material 11 contains a photoacid generator (PAG), a quencher component (amines), a surfactant, a leveling agent, and the like as components. Here, in this embodiment, the optimum blending amount of each component for obtaining a highly accurate resist pattern by liquid immersion exposure is calculated by a preliminary test. Further, in order to elute a part of the components in the solvent by the cleaning process of the resist material 11 performed in a later step, the amount of the components eluted in the solvent is calculated in advance. Then, the amount of elution of each component is increased and blended with the optimum blending amount of the components to prepare the resist material 11.

  Here, an example in which a chemically amplified positive resist is used as the resist material 11 will be described. However, the present invention can also be applied to a chemically amplified negative resist, and other than the chemically amplified resist. Even other resists can be applied. Moreover, although fluorine-containing resin was used here as a resin component which comprises the resist material 11, this invention is not limited to this. However, when a fluorine-containing resin is used, since the resin itself has high water repellency, a resist film made of the resist material 11 is formed on the substrate in a subsequent process, and the substrate is immersed in an immersion liquid. In this case, the elution of components from the resist film and the penetration of the immersion liquid are surely suppressed, which is preferable.

  Next, the resist material 11 and a solvent 12 made of, for example, water are mixed and stirred (S102). Here, as the solvent 12, the solvent 12 made of the same component as the immersion liquid used in the immersion exposure performed in the subsequent process is used. In this embodiment, since water is used as the immersion liquid as will be described later, water is used as the solvent 12. At this time, the mixing volume ratio of the resist material 11 and the solvent 12 is 1: 0.3 to 1, preferably 1: 0.5 to 0.7.

  Thereafter, the resist material 11 and the solvent 12 are separated by allowing to stand. At this time, since the resist material 11 is dissolved in an organic solvent, it is separated into a solvent phase (lower layer on the drawing) and an aqueous phase (upper layer on the drawing). At this time, a part of the above components are eluted from the resist material 11 into the solvent 12 as indicated by an arrow A, and a trace amount of water permeates into the resist material 11 from the solvent 12 as indicated by an arrow B. Mutually move.

An example of the elution amount of the component in this case is as follows. The cation component and the anion component eluted from the PAG are 1 to 10 × 10 ⁻¹⁰ mol / cm ² , and the quencher component (amine component) is 1 to 10 × 10. ^-12 mol / cm ² .

  Thereafter, the separated aqueous phase is removed by decantation. Here, the cleaning process of the resist material 11 described above, that is, the process from the mixing and stirring of the resist material 11 and the solvent 12 to the decantation of the solvent 12 through the separation of the resist material 11 and the solvent 12, Although it may be performed once, it is preferably repeated a plurality of times. At this time, the amount of the component eluted in the solvent 12 is almost determined by the combination of the constituent components of the resist material 11 and the solvent 12, and even if the above washing process is repeated a plurality of times, it exceeds a predetermined number of times. Almost no components are eluted. Here, the washing process is repeated three times until the components are not eluted.

  By performing the cleaning step, in the step of preparing the resist material 11 (S101), the resist material 11 is prepared by increasing the amount of the component by the amount of the component eluted into the solvent 12, and thus the resist material 11 is prepared. In this state, an optimum amount of components for performing immersion exposure is held.

  Next, a quality inspection is performed on the resist material 11 (S103). The quality control items of the resist material 11 include the moisture content, solid content concentration, metal content, number of particles, viscosity, transmittance, amount of each component, coating film thickness, sensitivity (finished line width), and the like. Here, the coating film thickness and sensitivity (finished line width) may be actually measured by applying the extracted lot of resist material to a substrate and performing immersion exposure on the substrate. Among the above-mentioned quality control items to be particularly noted are the water content, the solid content concentration, the amount of each component, and the sensitivity (finished line width).

  Next, the resist material 11 (OK) that has passed the quality inspection is introduced into the coater developer 21. On the other hand, the resist material 11 (NG) that has failed the quality inspection is discarded or the process returns to S101 to prepare the resist material 11.

  Next, a substrate (wafer) for applying the resist material 11 is introduced into, for example, the coater / developer 21, and a film to be processed (organic film) for forming a pattern is applied, and then a resist film is formed on the organic film. Application formation is performed (S104). Here, the manufacturing process after the introduction of the coater developer 21 will be described with reference to FIG.

  First, as shown in FIG. 2A, an antireflection film 14 made of an organic material is formed on a substrate 13. Next, the resist material 11 (see FIG. 1) is applied on the antireflection film 14 to form a resist film 11 '. Thereafter, pre-baking is performed to evaporate the organic solvent in the resist film 11 '.

  Next, the substrate 13 on which the resist film 11 ′ has been formed is introduced into an immersion exposure apparatus 22 (see FIG. 1) provided adjacent to the coater developer 21 to perform immersion exposure (S105 in FIG. 1). )). Specifically, as shown in FIG. 2B, the substrate 13 is immersed in an immersion liquid 15 made of water, for example, with the resist film 11 'facing upward. At this time, the resist material 11 (see FIG. 1) constituting the resist film 11 ′ is mixed in advance with the solvent 12 (see FIG. 1) made of the same component as the immersion liquid 15 to elute the components. The elution of components from the resist film 11 ′ into the immersion liquid 15 is suppressed.

Next, as shown in FIG. 2C, an exposure mask M is disposed between the resist film 11 ′ and a projection optical system (not shown) using ArF laser light disposed above as an exposure source. . In a state where the immersion liquid 15 is interposed between the projection optical system of the lens and the resist film 11 ', performs immersion exposure with an exposure amount of ^{20mJ / cm 2 ~40mJ / cm 2} . Here, ArF laser light is used as the exposure light h, but the exposure light h is not particularly limited, and may be any of g-line, i-line, KrF, F ₂ , and EUV.

  Thereafter, the exposed substrate 13 is again introduced into the coater developer 21 (see FIG. 1) (FIG. 1 (S106)). Then, as shown in FIG. 2D, after performing post-exposure baking, development is performed with a developer containing tetramethylammonium hydroxide (TMAH), and rinsing is performed with pure water. As a result, the exposed portion of the resist film 11 '(see FIG. 2C) is removed, and a resist pattern 11' 'is formed.

  According to the method of manufacturing the resist material 11 and the method of manufacturing a semiconductor device using the resist material 11, the resist material 11 is previously mixed with the solvent 12 made of the same component as the immersion liquid 15 and washed. The elution of components from the surface of 11 'into the immersion liquid 15 and the penetration of the immersion liquid 15 into the resist film 11' are suppressed. As a result, the concentration of the component on the surface of the resist film 11 ′ can be prevented from being lowered, so that the resolution of the surface of the resist film 11 ′ can be prevented from being lowered. Further, since the penetration of the immersion liquid 15 into the resist film 11 ′ is suppressed, it is possible to prevent a decrease in resolution due to the swelling of the resist film. From the above, the shape deterioration and dimensional error of the resist pattern 11 '' can be suppressed, and the yield of the semiconductor device to be manufactured can be improved.

  In addition, when the resist pattern 11 ″ having the same shape is formed using the resist material 11 of different lots, the liquid is immersed from the resist film 11 ′ formed on the substrate 13 by performing the cleaning process as described above. The elution of components into the liquid 15 is suppressed. Thereby, even if there is a difference in film thickness or the like between the resist films 11 ′ formed by the resist materials 11 of different lots, there is no difference in the elution amount of the components into the immersion liquid 15. 'Prevents variations in the amount of components from being out of tolerance. Therefore, the dimensional error of the resist pattern 11 ″ formed using the resist material 11 of different lots can be suppressed within an allowable range, and the line width uniformity of the resist pattern 11 ″ can be improved.

  Furthermore, according to this embodiment, in order to prepare the resist material 11 by increasing the amount of components eluted in the solvent 12 by the cleaning process, immersion exposure is performed in the state of being immersed in the immersion liquid 15. A resist film 11 ′ containing a component adjusted to an optimum amount to be performed can be formed. Therefore, by exposing and developing such a resist film 11 'to form a resist pattern 11' ', the dimensional accuracy of the resist pattern 11' 'can be improved.

  Further, since the elution of the components into the immersion liquid 15 is suppressed, the contamination of the immersion exposure apparatus due to the components of the resist material 11 is suppressed as compared with the conventional immersion exposure method described in the background art. be able to.

  In addition, although the manufacturing method of the resist material 11 was demonstrated in the said embodiment, you may perform the same application | coating pre-processing also about the organic material which comprises the anti-reflective film 14. FIG. This organic material is also constituted by dissolving, for example, an acrylic resin having chromophore in an organic solvent, and the organic material contains a thermal cross-linking agent, a surfactant, a pH adjuster and the like as additives.

  In this case, as in the case of the resist material 11 described with reference to FIG. 1, the organic material constituting the antireflection film 14 is mixed with the solvent 12 made of the same component as the immersion liquid 15 and washed in advance. A part of the components of the organic material is eluted in the solvent 12. At this time, a small amount of moisture permeates from the solvent 12 into the organic material.

  Thereafter, as shown in FIG. 2A, this organic material is applied onto the substrate 13 to form an antireflection film 14, and a resist film 11 ′ is formed on the antireflection film 14. At this time, the edge side 14a of the antireflection film 14 is exposed from the resist film 11 '. Thereafter, as shown in FIG. 2B, the substrate 13 in this state is immersed in the immersion liquid 15. At this time, the edge side 14a of the antireflection film 14 comes into contact with the immersion liquid 15. However, the components may be eluted from the edge side 14a of the antireflection film 14 into the immersion liquid 15 by performing the above-described cleaning process. It is suppressed.

  Thus, as shown in FIG. 2D, after the resist pattern 11 ″ is formed, the antireflection film 14 is patterned when the antireflection film 14 is patterned by etching using the resist pattern 11 ″. The pattern dimensional error caused by the density difference of the components is suppressed between the edge side 14a and the center side.

  Although the example of the antireflection film 14 has been described here, it may be an organic film formed under the resist film 11 ′, and may be a top coat film, for example.

(Modification 1)
In the above-described embodiment, as shown in FIG. 3, the solvent 12 used for the cleaning process of the resist material 11 may be used as an immersion liquid for immersion exposure. In this case, quality inspection (S201) such as the presence or absence of impurities and particles is performed on the solvent 12 after the elution process of the above components, and if the amount of impurities and particles is within an allowable range (OK), It is introduced into the immersion exposure apparatus 22. 2B, since the components from the resist material 11 (see FIG. 3) have already been eluted in the immersion liquid 15, the immersion liquid 15 is removed from the resist film 11 ′. It is difficult for the components to elute inside, and the elution of the components is reliably prevented.

  Even with such a method of manufacturing a semiconductor device, the same effects as in the embodiment can be obtained. However, in this case, in order to prevent contamination of the lens of the immersion exposure apparatus immersed in the immersion liquid 15, the immersion exposure apparatus needs to be separately cleaned.

  An example of a method for manufacturing a semiconductor device using the method for manufacturing an organic material of the present invention will be specifically described.

(Example)
Resist materials 11-1, 11-2, and 11-3 for ArF exposure of different lots were prepared. First, 4 liters of resist material 11-1 was stirred and mixed with 2 liters of solvent 12 (water), followed by a washing process in which liquid separation (stationary time 5 minutes) and decantation were repeated three times. As a result, the resist material 11-1 was subjected to liquid separation extraction. The same processing was performed for the lot differences (11-2, 11-3) of the resist material 11-1.

  Next, as shown in FIG. 2A, the substrate 13 (8-inch wafer) is introduced into the coater developer 21 (coater developer ACT-8 (manufactured by Tokyo Electron)) shown in FIG. 14 was applied to a film thickness of 85 nm. Next, the resist material 11-1 (Lot 1) was applied on the antireflection film 14 to a thickness of 150 nm to form a resist film 11'-1. Thereafter, the resist film 11'-1 was pre-baked at 100 ° C for 90 seconds.

Thereafter, as shown in FIG. 2B, the substrate 13 on which the resist film 11′-1 is formed is introduced into the immersion exposure apparatus 22 (see FIG. 1), and the substrate 13 is immersed in water. It was immersed in the liquid 15. Subsequently, as shown in FIG. 2 (c), an exposure mask M is placed on the resist film 11 '-1 at ^{20mJ / cm 2 ~40mJ / cm 2} , was carried out immersion exposure. After the exposure, as shown in FIG. 2D, the substrate 13 was again introduced into the coater developer 21 (see FIG. 1), and post-exposure baking was performed at 110 ° C. for 90 seconds. Subsequently, the film was developed with a developer (TMAH 2.38% aqueous solution) for 30 seconds and rinsed with pure water. As described above, a line-and-space resist pattern 11 ″ -1 having a line width target dimension of 65 nm was formed.

  Further, resist patterns 11 ″ -2 and 11 ″ -3 having the same shape were formed by the same process as described above using the resist materials 11-2 and 11-3 of different lots described above.

  As a result, for a line-and-space pattern with a line width target dimension of 65 nm, the line width uniformity within the wafer surface was 9.2 nm at 3σ (6.2 nm in the range).

(Comparative example)
On the other hand, as a comparative example of the above embodiment, the resist pattern 11 is formed by the same method except that the resist materials 11-1, 11-2, and 11-3 of different lots are used and the cleaning process is not performed as described above. '' -1, 11 ''-2, 11 ''-3 were formed. As a result, for a 65 nm line and space pattern, the line width uniformity within the wafer surface was 19.5 nm at 3σ (12 nm in the range).

  From the above, it was confirmed that the line width uniformity of the resist pattern 11 ″ formed using the resist material 11 of different lots is improved by performing the cleaning process of the resist material 11.

It is process drawing for demonstrating 1st Embodiment which concerns on the manufacturing method of the semiconductor device of this invention. FIG. 6 is a manufacturing process sectional view (No. 2) for describing the first embodiment of the manufacturing method of the semiconductor device of the invention; It is process drawing for demonstrating the modification 1 of 1st Embodiment which concerns on the manufacturing method of the semiconductor device of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Resist material, 11 '... Resist film, 11' '... Resist pattern, 12 ... Solvent, 13 ... Substrate, 14 ... Antireflection film, 15 ... Immersion liquid

Claims (3)

A method of manufacturing a semiconductor device in which an organic material is applied on a substrate to form an organic film, and then immersion exposure is performed in a state where the substrate is immersed in an immersion liquid. A first step of mixing and washing with a solvent composed of the same component as the immersion liquid, and eluting a part of the component in the organic material into the solvent;
Applying the washed organic material on the substrate to form the organic film;
First , immersion exposure is performed in a state where the solvent after the organic material is washed in the first step is used as an immersion liquid and the substrate on which the organic film is formed is immersed in the immersion liquid. With 3 steps
A method for manufacturing a semiconductor device. The organic film is a resist film
A method for manufacturing a semiconductor device according to claim 1 . The organic film pattern is formed after the third step.
A method for manufacturing a semiconductor device according to claim 1 .

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