JP2006039129A - Laminated structure for liquid immersion exposure, liquid immersion exposure method, manufacturing method of electronic device, and electronic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress occurrence of resist formation abnormalities due to the formation of a hardly soluble layer in a photoresist layer in a liquid immersion exposure method making the photoresist layer an exposure object. <P>SOLUTION: A laminated structure for liquid immersion exposure is provided with a resist protecting layer 4, having at least partly overlapped transmission light wavelength band with a photosensitive wavelength band of a photoresist layer 3 on the photoresist layer 3. The resist protection layer 4 is constituted to be dissolved in only a polar solvent, such as a fluorine-based organic solvent and an alkali aqueous solvent, and an acid and an acid generating agent are prevented from flowing out from the photoresist layer 3. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a layered structure for immersion exposure, an immersion exposure method, a method for manufacturing an electronic device, and an electronic device, in particular an immersion for performing exposure by interposing a high refractive index medium between an exposure projection lens and an exposure target. The present invention relates to a laminated structure for immersion exposure suitable for exposure, an immersion exposure method that can be performed by this laminated structure, various electronic devices such as semiconductor devices, and a method for manufacturing an electronic device.

  Starting with electronic devices such as CCD (Charge Coupled Device), CMOS (Complementary Metal Oxide Semiconductor) sensors, LSI (Large Scale Integrated Circuit), and MEMS (Micro Electrical Mechanical System), manufacturing semiconductor lasers and optical devices, For example, the photolithography technique is applied to the production of a master for producing an optical disk and the like, and to a wide variety.

  In this photolithography, fine processing is performed on the photoresist layer itself, or patterning is performed by forming fine openings in the photoresist layer, and the patterned photoresist layer is used as an etching mask or an ion implantation mask. Alternatively, by using it as a lift-off mask, it can be applied to the manufacture of the above-described various elements or devices.

Recently, further miniaturization is demanded in various fields such as semiconductor devices, optical devices, MEMS, optical disks, and so on, and high precision miniaturization of processing and patterning for photoresists is demanded.
For example, in semiconductor integrated circuits, the trend toward miniaturization of circuit elements and circuit patterns with increasing integration density is increasing, and there is a need for high-precision exposure miniaturization in photolithography used in the manufacturing process. For example, ultraviolet light is used as the light.

In addition, in order to make the pattern finer by shortening the wavelength of the ultraviolet light applied to the resist layer, it is necessary to improve the resolving power in condensing irradiation to the resist layer by the projection lens.
Here, the resolving power of the irradiation light is such that the numerical aperture of the projection lens is N.sub. A. Is expressed by [Equation 1]. In [Equation 1], k ₁ is a coefficient determined by a resist material or a super-resolution technique.

On the other hand, the numerical aperture N.I. A. As is clear from the relational expression expressed by [Equation 2], the depth of focus becomes shallow, and there arises a problem that the exposure pattern changes greatly when the exposure target is slightly shifted from the focus.
In [Expression 2], k ₂ is a coefficient determined by a resist material or a super-resolution technique.

However, the numerical aperture of the projection lens N.I. A. Is already approaching the limit, and the current mainstream exposure light source, that is, a KrF excimer laser with a central wavelength of 248 nm, an ArF excimer laser with a shorter central wavelength of 193 nm, and a central wavelength of 157 nm Even if exposure is performed using an F ₂ excimer laser, it is difficult to cope with finer exposure patterns, and the above-described margin and yield reduction based on the depth of focus cannot be avoided.

Further, in the pattern exposure, studies have been made to reduce the above-mentioned k ₁ , that is, to increase the resolving power by using a phase shift mask or modified illumination, or to increase k ₂ , that is, to increase the depth. Such a super-resolution technique has a high mask cost and a complicated design and creation of the mask, resulting in a decrease in yield.

In contrast, a liquid immersion exposure method that improves the effective resolution by interposing a high-refractive-index medium such as water between the projection lens and a photoresist coated on, for example, a semiconductor substrate. (For example, see Non-Patent Document 1).
In addition, proposals have been made to apply this immersion exposure method to the formation of fine circuit patterns (for example, see Non-Patent Document 2, Patent Documents 1 and 2).

In recent years, in this immersion exposure method, an exposure apparatus provided with a supply mechanism and a recovery mechanism for a high refractive index medium such as pure water tends to be widely used.
14A and 14B show a schematic configuration diagram of this exposure apparatus and a schematic diagram of an exposure principle. According to the apparatus shown in FIG. 14A, by holding pure water between the projection lens and the resist layer on the semiconductor substrate (for example, 1 mm in thickness), effective irradiation light from the projection lens is obtained as shown in FIG. 14B. Exposure can be performed with improved resolution.
DWPohl, W.Denk & M.Lanz, Appl.Phys.Lett.44652 (1984) H. Kawata, JMCarter. A, Yen, HISmith, Microelectronic Engineering 9 (1989) USP 5,121,256 (Jun 9,1992) EP 0023 231 A1 (04.02.1981)

However, when the photoresist layer is exposed by the immersion exposure method, a high refractive index medium such as pure water is in direct contact with the resist layer, which causes a problem different from the conventional exposure method.
For example, as a resist material in an immersion exposure method using an ArF excimer laser with a central wavelength of 193 nm as an exposure light source, a circuit using a negative chemically amplified resist for exposure with a conventional ArF light source, so-called dry ArF light source exposure, is used. When photolithography is applied to the pattern formation, as shown in FIG. 15, a slightly soluble region is formed on the top of the resist layer that is in direct contact with water, and the cross section of the molded resist has a T-top shape. An abnormal shape occurs.

Such a shape abnormality is caused by the intrusion of pure water into the resist layer and at the same time, the acid generator composing the resist layer and the acid generated during exposure flow out into the pure water, making direct contact with the pure water. This is because the region where the acid generator and acid concentration in the upper part of the resist layer to be reduced is a poorly soluble region.
In addition, a proposal has been made to form a resist protective layer in order to avoid contact between the resist layer and pure water. However, after immersion exposure, resist protection prior to the formation of a circuit pattern based on development of the resist layer. It becomes difficult to perform layer peeling.

  That is, the resist protective layer is configured not to dissolve in pure water, but when the resist protective layer is peeled off in an organic solvent, the resist layer may be dissolved at the same time. For example, in the case of performing dry etching using plasma, a delay occurs in the throughput, that is, the time until etching is completed, and defects are easily generated due to generation of particles. Furthermore, these stripping methods provide a separate process for stripping the resist protective layer, which complicates the manufacture of various devices and inevitably reduces mass productivity.

  The present invention provides a laminated structure for immersion exposure, an immersion exposure method, a method for manufacturing an electronic device, and an electronic device that can solve various problems in photolithography by the immersion exposure method described above. Is.

  The laminated structure for immersion exposure according to the present invention is a laminated structure for immersion exposure in which exposure is performed by interposing a high refractive index medium between an exposure projection lens and an exposure object, and the exposure object is a photoresist. A photoresist protective layer is formed on the photoresist layer, the photosensitive wavelength band of the photoresist layer is a short wavelength region of 193 nm or less, the photosensitive wavelength band of the photoresist layer, and the resist protection layer The transmitted light wavelength band of the layer is at least partially overlapped, and the resist protective layer is a resin having a linear or cyclic aliphatic structural unit, and a fluorine-based organic solvent and an alkaline aqueous solvent. It is characterized by only dissolving.

In the laminated structure for immersion exposure, the resist protective layer is configured not to dissolve, penetrate or swell in a neutral or acidic aqueous solvent.
The present invention is also characterized in that, in the laminated structure for immersion exposure, the high refractive index medium is a neutral or acidic aqueous solvent.
The present invention is also characterized in that, in the laminated structure for immersion exposure, the aliphatic structural unit has a hydrophilic functional group.
Further, the present invention is the liquid immersion exposure laminated structure, wherein the aliphatic structural unit has at least one of a carbonyl group, a sulfone group, a hydroxyl group, and a carboxyl group as the hydrophilic functional group. Features.
The present invention is also characterized in that, in the laminated structure for immersion exposure, the aliphatic constituent unit has an atom or an atomic group that stabilizes the resist protective layer.
Further, the present invention provides the laminated structure for immersion exposure, wherein the aliphatic constituent unit contains an atom or an atomic group that improves the affinity between the resist protective layer and the fluorinated organic solvent or the alkaline aqueous solvent. It is characterized by having.
Further, the present invention is the above-described immersion exposure laminated structure, wherein the aliphatic constituent unit is an acrylic constituent unit, a COMA (cycloolefin / maleic anhydride copolymer) constituent unit, a cycloolefin constituent unit, VEMA (vinyl ether / maleic anhydride copolymer) -based structural unit is at least one type.
The present invention is also characterized in that, in the laminated structure for immersion exposure, the resist layer is made of a chemically amplified resist.
Further, the present invention is characterized in that, in the laminated structure for immersion exposure, the resist protective layer is a layer having an antireflection function (TARC: Top Anti Reflective Coating).

  An immersion exposure method according to the present invention is an immersion exposure method for performing exposure by interposing a high refractive index medium between an exposure projection lens and an exposure target, wherein the exposure target is a photoresist layer, The photosensitive wavelength band of the photoresist layer is a short wavelength region of 193 nm or less, and the photosensitive wavelength band of the photoresist layer and the transmitted light wavelength band of the resist protective layer are at least partially overlapped, A step of applying a resist protective material dissolved in a fluorine-based organic solvent on the photoresist layer, and forming a resist protective layer by removing the fluorine-based solvent; and a liquid for the photoresist layer from the resist protective layer. A step of performing immersion exposure, and a step of dissolving and removing the resist protective layer in an alkaline aqueous solvent. And forming a resin having a family-based structural units.

Further, the present invention is characterized in that, in the immersion exposure method, the resist protective layer is configured not to dissolve, penetrate or swell in a neutral or acidic aqueous solvent. In the immersion exposure method, the high refractive index medium is a neutral or acidic aqueous solvent.
Further, the present invention is characterized in that, in the immersion exposure method, the aliphatic constituent unit has a hydrophilic functional group.
Further, the present invention is characterized in that, in the immersion exposure method, the aliphatic structural unit has at least one of a carbonyl group, a sulfone group, a hydroxyl group, and a carboxyl group as the hydrophilic functional group. To do.
Moreover, the present invention is characterized in that, in the immersion exposure method, the aliphatic constituent unit has an atom or an atomic group that stabilizes the resist protective layer.
In the immersion exposure method, the aliphatic structural unit may have an atom or an atomic group that improves the affinity between the resist protective layer and the fluorinated organic solvent or the alkaline aqueous solvent. It is characterized by.
In the immersion exposure method, the aliphatic structural unit may be an acrylic structural unit, a COMA (cycloolefin / maleic anhydride copolymer) structural unit, a cycloolefin structural unit, VEMA ( (Vinyl ether / maleic anhydride copolymer) system constituent unit having at least one kind.
In the immersion exposure method, the resist layer is made of a chemically amplified resist.
In the immersion exposure method, the resist protective layer may be a layer having an antireflection function (TARC: Top Anti Reflective Coating).

A method of manufacturing an electronic device according to the present invention is a method of manufacturing an electronic device having a photolithography process, wherein the photosensitive wavelength band of the photoresist layer is a short wavelength region of 193 nm or less, and the photosensitive wavelength of the photoresist layer is The band and the transmitted light wavelength band of the resist protective layer are at least partially overlapped, and in the photolithography step, a resist protective material dissolved in a fluorine-based organic solvent is applied on the photoresist layer. And a step of forming a resist protective layer by removing the fluorine-based solvent, and immersion exposure is performed on the photoresist layer by interposing a high refractive index medium between the projection lens for exposure and the resist protective layer. Process,
And removing the resist protective layer by dissolving it in an alkaline aqueous solvent, wherein the resist protective layer is formed as a resin having a linear or cyclic aliphatic structural unit.

According to the present invention, in the method for manufacturing an electronic device, the resist protective layer is configured not to dissolve, penetrate, or swell in a neutral or acidic aqueous solvent.
According to the present invention, in the method for manufacturing an electronic device, the high refractive index medium is a neutral or acidic aqueous solvent.
Further, the invention is characterized in that, in the method for manufacturing an electronic device, the aliphatic structural unit has a hydrophilic functional group.
In the method for manufacturing an electronic device according to the present invention, the aliphatic structural unit has at least one of a carbonyl group, a sulfone group, a hydroxyl group, and a carboxyl group as the hydrophilic functional group. And
In the method for manufacturing an electronic device according to the present invention, the aliphatic structural unit has an atom or an atomic group that stabilizes the resist protective layer.
In the method for manufacturing an electronic device according to the invention, the aliphatic constituent unit has an atom or an atomic group that improves the affinity between the resist protective layer and the fluorine-based organic solvent or the alkaline aqueous solvent. It is characterized by that.
According to the present invention, in the method for manufacturing an electronic device, the aliphatic constituent unit is an acrylic constituent unit, a COMA (cycloolefin / maleic anhydride copolymer) constituent unit, a cycloolefin constituent unit, or VEMA. (Vinyl ether / maleic anhydride copolymer) It has at least one type of structural unit.
According to the present invention, in the method for manufacturing an electronic device, the resist layer is made of a chemically amplified resist.
In the method of manufacturing an electronic device, the resist protective layer is a layer having an antireflection function (TARC: Top Anti Reflective Coating).

  An electronic device according to the present invention is an electronic device having a fine structure, wherein a resist protective layer is formed on a photoresist layer as a resin having a linear or cyclic aliphatic structural unit, and the photoresist layer The photosensitive wavelength band is a short wavelength region of 193 nm or less, and the photosensitive wavelength band of the photoresist layer and the transmitted light wavelength band of the resist protective layer are at least partially overlapped. On the other hand, exposure was performed by immersion exposure in which a high refractive index medium was interposed between the projection lens for exposure and the resist protective layer, and both the resist layer and the resist protective layer were removed with an alkaline aqueous solvent. The fine structure is formed by a pattern or by processing using the pattern.

In the electronic device, the resist protective layer may be configured not to dissolve, penetrate, or swell in a neutral or acidic aqueous solvent.
In the electronic device, the high refractive index medium is a neutral or acidic aqueous solvent.
In the electronic device, the aliphatic structural unit has a hydrophilic functional group.
In the electronic device, the aliphatic structural unit includes at least one of a carbonyl group, a sulfone group, a hydroxyl group, and a carboxyl group as the hydrophilic functional group.
In the electronic device, the aliphatic structural unit has an atom or an atomic group that stabilizes the resist protective layer.
In the electronic device, the aliphatic structural unit includes an atom or an atomic group that improves the affinity between the resist protective layer and the fluorine-based organic solvent or the alkaline aqueous solvent. And
In the electronic device, the aliphatic structural unit may be an acrylic structural unit, a COMA (cycloolefin / maleic anhydride copolymer) based structural unit, a cycloolefin based structural unit, a VEMA (vinyl ether. Maleic anhydride copolymer) having at least one type of structural unit.
According to the present invention, in the electronic device, the resist layer is made of a chemically amplified resist.
According to the present invention, in the electronic device, the resist protective layer is a layer having an antireflection function (TARC: Top Anti Reflective Coating).

  According to the laminated structure for immersion exposure according to the present invention, in immersion exposure for exposing a photoresist layer, a resist protective layer having a transmitted light wavelength band at least partially overlapping with the photosensitive wavelength band of the photoresist layer is provided. Since it is formed on the photoresist layer with a resin having a linear or cyclic aliphatic structural unit, for example, in the immersion exposure method using an ArF excimer laser with a central wavelength of 193 nm as an exposure light source, It is possible to suppress the occurrence of resist shape abnormality due to the formation of the hardly soluble layer.

  That is, the high refractive index medium interposed between the projection lens and the object to be exposed, for example, pure water enters the photoresist layer, and the acid generator that constitutes the photoresist layer into the pure water and the acid generator are generated during exposure. Acid outflow can be avoided by the presence of a resist protective layer formed on the photoresist layer, and by suppressing the formation of a locally poorly soluble layer, the immersion exposure method can function more effectively. It was possible to form a resist pattern.

  In addition, according to the laminated structure for immersion exposure according to the present invention, affinity for a polar solvent such as a fluorine-based organic solvent can be obtained by introducing a polar atom such as fluorine (F) into the aliphatic structural unit of the resist protective layer. And improvement of the stability against other organic solvents. Furthermore, by combining with the introduction of a hydrophilic functional group such as a carbonyl group, a sulfone group, a hydroxyl group, or a carboxyl group, the composition can be dissolved only in a fluorine-based organic solvent and an alkaline aqueous solvent.

  Therefore, according to the laminated structure for immersion exposure according to the present invention, since the resist protective layer described above is configured to dissolve only in the fluorine-based organic solvent and the alkaline aqueous solvent, in the formation of the resist protective layer, The dissolution of the photoresist layer during the formation of the protective layer can be avoided, and in the development after forming a latent image of the photoresist layer by exposure, the resist protective layer is peeled off and the photoresist layer is developed simultaneously with an alkaline aqueous solvent. be able to.

  Specifically, the configuration of the resist protective layer is such that most of the upper portion of the photoresist layer is protected by not dissolving, penetrating or swelling with respect to a neutral or weakly acidic aqueous solvent. be able to. Furthermore, by setting the acidity of the resist protective layer to the same level as that of the photoresist layer, an equilibrium is formed between the photoresist layer and the resist protective layer, and the outflow of acid from the photoresist layer is more reliably performed. It can be avoided.

  In addition, by forming a resist protective layer by applying a resist protective material using a highly polar solvent typified by a fluorine-based organic solvent, dissolution of the photoresist layer may occur during the formation of the resist protective layer. Can be avoided. Furthermore, by removing the resist protective layer with an alkaline aqueous solvent, the photoresist layer can be developed at the same time, so the process from immersion exposure to development can be made more efficient, and in response to market demands. Semiconductor devices and electronic devices can be supplied more quickly.

  According to the laminated structure for immersion exposure and the immersion exposure method according to the present invention, the resist protective layer is an antireflection functional layer (TARC), for example, having a refractive index different from that of the photoresist layer. For example, by adjusting the thickness, it is possible to reduce the variation in the pattern line width that occurs because the standing wave effect based on multiple interference in the photoresist layer varies depending on the thickness of the photoresist layer. It is said.

In addition, according to the method for manufacturing an electronic device according to the present invention, it is possible to simplify the manufacture of various devices and improve the mass productivity by introducing the above-described immersion exposure method to manufacture the electronic device. Furthermore, the environmental load in manufacturing can be reduced by reducing the number of processes.
Since the electronic device according to the present invention can avoid the occurrence of defects due to the generation of particles in the peeling of the resist protective layer, it is important according to the present invention to ensure yield and improve reliability. Many effects can be brought about.

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these embodiments.
First, an embodiment of the laminated structure for immersion exposure according to the present invention will be described with reference to FIGS.

Embodiment Example of Layered Structure for Immersion Exposure FIG. 1A is a schematic cross-sectional view showing the configuration of an example of a layered structure for immersion exposure according to the present invention.
In this embodiment, the immersion exposure multilayer structure 1 includes at least a substrate 2 made of, for example, Si, a photoresist layer 3 made of, for example, a chemically amplified resist formed on the substrate 2, and a photoresist layer 3. And a resist protective layer 4 made of a resin made of an aliphatic constituent unit such as an acrylic constituent unit.

The photosensitive wavelength band of the photoresist layer 3 is, for example, a short wavelength region including a central wavelength of 193 nm when an ArF excimer laser is used as an exposure light source. The photosensitive wavelength band of the photoresist layer 3 and the transmitted light wavelength of the resist protective layer 4 The belt is configured to at least partially overlap. In this embodiment, the photosensitive wavelength band of the photoresist layer 3 and the transmitted light wavelength band of the resist protective layer 4 are both configured to include 193 nm.
The resist protective layer 4 is made of a resin having a linear or cyclic aliphatic structural unit as described later.

FIG. 1B is a schematic diagram showing the shape of a resist after development that can be obtained from the laminated structure for immersion exposure according to the present invention.
According to the laminated structure for immersion exposure according to the present invention, the resist protective layer 4 on the photoresist layer 3 allows the high refractive index medium, for example, pure water, which is interposed between the projection lens and the object to be exposed to enter the photoresist layer. Intrusion and outflow of the acid generator that constitutes the photoresist layer into the pure water and the acid generated during exposure are avoided, and the occurrence of shape abnormalities such as T-top shapes due to the formation of locally poorly soluble layers Thus, as shown in FIG. 1B, it is possible to form a resist having, for example, a rectangular cross-sectional shape after development.

In this configuration, the resist protective layer 4 is preferably configured not to be dissolved in pure water as will be described later, and the acidity of the resist protective layer 4 is desirably set to the same level as that of the photoresist layer 3. As a result, an equilibrium is formed between the photoresist layer 3 and the resist protective layer 4 so that the acid migration does not substantially proceed, so that the outflow of the acid from the photoresist layer 3 can be more reliably avoided. it can.
2A and 2B are a schematic diagram showing a laminated structure when the acidity of the resist protective layer 4 is extremely higher than the acidity of the photoresist layer 3, and a post-development that can be obtained from this laminated structure. It is a schematic diagram which shows the shape of a resist.

  When the acidity of the resist protective layer 4 is extremely lower than the acidity of the photoresist layer 3, the concentration of the acid generator constituting the photoresist layer 3 and the acid generated during exposure is locally reduced. The shape of the photoresist layer 3 after development and removal of the resist protective layer 4 becomes a so-called T-top shape, but the acidity of the photoresist layer 3 is extremely higher than the acidity of the resist protective layer 4 As shown in FIG. 2A, since the acidity of the resist protective layer 3 is increased by the inflow of acid from the resist protective layer 4, the shape of the photoresist layer 3 after development becomes a so-called tapered shape. Accordingly, the acidity of the resist protective layer 4 in the laminated structure for immersion exposure according to the present invention is adjusted and selected to such an extent that an equilibrium is formed in which the acid transfer does not substantially proceed with the photoresist layer 3. It is desirable.

Next, the structure of the resist protective layer 4 of the multilayer structure 1 for immersion exposure according to the present invention will be described.
FIG. 3A and FIG. 3B are schematic diagrams of an example of an acrylic structural unit that can be used as a structural unit of a resin for forming the resist protective layer 4 constituting the laminated structure for immersion exposure according to the present invention.
As shown in FIG. 3A, the resin constituting the resist protective layer 4 in the laminated structure for immersion exposure according to the present invention comprises an aliphatic constituent unit, for example, an acrylic constituent unit.

  In addition, as shown in FIG. 3B, the resin constituting the resist protective layer is stabilized by etching resistance such as an adamantyl group or an alicyclic atomic group on the side chain of an aliphatic structural unit, for example, an acrylic structural unit. It is also possible to have a structure having an atomic group that does not have an aliphatic structure unless the solubility in an alkaline aqueous solvent described later is extremely reduced or the acid transfer with the above-described photoresist layer is not excessive. The unit structure can be selected as appropriate.

  In addition, since the aromatic resin composed of an aromatic ring having an unsaturated bond such as a phenol-based structural unit includes 193 nm in the absorption wavelength band in terms of structure, in the laminated structure for immersion exposure according to the present invention, an aliphatic resin is used. It is desirable to form the resist protective layer 4 by a system structural unit. As the aliphatic structural unit, various structural units other than the acrylic structural unit can be used as will be described later.

The structure of the side chain of the aliphatic structural unit constituting the resin forming the resist protective layer 4 will be described.
FIG. 4A to FIG. 4C show an aliphatic structural unit that can be a structural unit of a resin that forms the resist protective layer 4 that constitutes the laminated structure for immersion exposure according to the present invention, for example, side chain in an acrylic structural unit. It is the schematic diagram which showed the example of the structure.

As shown in FIG. 4A, the hydrophilicity is improved by disposing a hydrophilic functional group such as a carbonyl group, a hydroxyl group, or a carboxyl group on the side chain of the aliphatic structural unit, and for example, the side chain shown as R ₁ By placing, for example, a highly polar atom or atomic group such as fluorine (F) which stabilizes the resist protective layer 4 at the terminal, neutral to acidic water, PGMEA (propylene glycol monomethyl ether acetate), etc. The structure does not react with non-fluorinated organic solvents, or does not dissolve, penetrate or swell.

  Further, as shown in FIGS. 4B and 4C, an atom or atomic group such as sodium (Na) or potassium (K) is introduced into the side chain of the aliphatic structural unit, or is formed by this aliphatic structural unit. The acidity and pH of the resist protective layer 4 can be adjusted by adding acidic and alkaline additives to the resin.

  The acidity and pH can be selected so that the resist protective layer 4 and the photoresist layer 3 do not react with each other, and the movement of the acid in both layers can be maintained in equilibrium. It can be set as the structure which the acid diffusion for pattern formation in the layer 3 and the melt | dissolution of the resist protective layer 4 and the photoresist layer 3 to the alkaline aqueous solvent in the image development processing mentioned later progress. Needless to say, the acid diffusion in the photoresist layer 3 described above can be defined using Le Chatelier's law.

5A to 5C show an aliphatic structural unit that can be used as a structural unit of a resin that forms the resist protective layer 4 constituting the laminated structure for immersion exposure according to the present invention, for example, side chain in an acrylic structural unit. It is the schematic diagram which showed the other example of the structure.
As shown in FIG. 5A, a sulfone group can be used as the hydrophilic functional group arranged in the side chain of the aliphatic structural unit. Further, as shown in FIGS. 5B and 5C, an atom or atomic group such as sodium (Na) or potassium (K) is introduced into the side chain of the aliphatic structural unit, or is formed by this aliphatic structural unit. It is possible to adjust the acidity and pH of the resist protective layer 4 by adding acidic and alkaline additives to the resin.

  As described above, in the laminated structure for immersion exposure according to the present invention, examples of the structure of the side chain of the aliphatic structural unit forming the resist protective layer 4 include a carbonyl group, a sulfone group, a hydroxyl group, and a carboxyl group. It can also be set as the structure which has an atom and atomic groups, such as a fluorine which improves the affinity of the resist protective layer 4, and a fluorine-type organic solvent or an alkaline aqueous solvent. In addition, the resist protective layer 4 may be configured to have atoms or atomic groups such as an adamantyl group that stabilizes the resist protective layer 4.

  By appropriately selecting these functional groups, atoms or atomic groups to constitute the resist protective layer 4, the resist protective layer 4 is dissolved only in a fluorine-based organic solvent and an alkaline aqueous solvent, and is neutral or acidic aqueous. As a configuration that does not dissolve, permeate, or swell in the solvent, it is possible to have a configuration in which an acid balance is established between the photoresist layer 3 during exposure and during non-exposure.

  Here, the neutral or acidic aqueous solvent in which the resist protective layer 4 forming the laminated structure for immersion exposure according to the present invention is not dissolved, penetrated or swelled generally has a pH of 6.5 to 7.5 or less. A certain water or aqueous solution is referred to, but when considering nitrogen-derived component contamination such as amine contamination due to various sources such as the human body, paints, and dustproof filters that are present at the time of manufacture, the pH is closer to the alkaline side, for example, about pH 8.0 It is necessary to consider the dissolution or penetration or swelling of water in water or aqueous solutions.

  In the above-described embodiment of the laminated structure for immersion exposure according to the present invention, an example in which an acrylic constituent unit is used as an aliphatic constituent unit constituting the resin forming the resist protective layer 4 has been described. Examples of the group structural unit include a COMA (cycloolefin / maleic anhydride copolymer) system structural unit shown in FIGS. 6A and 6B, a cycloolefin system structural unit shown in FIGS. 7A and 7B, and a VEMA ( (Vinyl ether / maleic anhydride copolymer) system structural unit and the like, and various other structural units can be mentioned. Further, as shown in FIG. 9A and FIG. 9B, for example, an acrylic structural unit as a main structural unit, other aliphatic groups A hybrid resin with a system structural unit can also be mentioned.

In the laminated structure for immersion exposure according to the present invention, the resist protective layer 4 may be so-called TARC (Top Anti Reflective Coating) having an antireflection function.
FIG. 10 is a schematic diagram showing changes in the thickness of the photoresist layer due to the substrate shape, that is, the process step. When a difference occurs in the thickness of the photoresist layer as described above, a standing wave due to multiple interference is generated in the photoresist layer when the photoresist layer is exposed, and the line width of the photoresist layer varies.

FIG. 11A and FIG. 11B are schematic diagrams showing the principle of multiple interference suppression when a resist protective layer is used as a TARC in the laminated structure for immersion exposure according to the present invention, and a case where only a photoresist layer is used and a case where TARC is used. It is a schematic diagram which shows the fluctuation | variation of the standing wave in.
As shown in FIG. 11A, exposure light applied to the photoresist layer 3 in immersion exposure is formed by forming the resist protective layer 4 on the photoresist layer 3 as a layer having a refractive index different from that of the photoresist layer 3. Are mutually canceled by the phase difference of each reflected light when reflected by the upper surface and the lower surface of the TARC.

  In this way, in the laminated structure for immersion exposure according to the present invention, by selecting the refractive index and the layer thickness of the resist protective layer 4, the phase of each reflected light is reversed and the multiple interference is suppressed, Changes in the resist line width due to the standing wave effect can be reduced as shown in FIG. 11B, and thereby the fluctuations in the pattern line width finally formed on the substrate can be reduced.

  Next, an embodiment of the immersion exposure method according to the present invention will be described with reference to FIGS.

Embodiment of Immersion Exposure Method An immersion exposure method according to the present invention is an immersion exposure method for a photoresist layer constituting the above-described laminated structure for immersion exposure according to the present invention, as shown in FIG. First, by applying a resist protective material dissolved in a fluorine-based organic solvent on the photoresist layer, and removing the fluorine-based solvent through, for example, pre-baking and cooling to form a resist protective layer, for example, a central wavelength A layered structure for immersion exposure is formed, which includes a resist protective layer having optical transparency to exposure light by an 193 nm ArF excimer laser and a photoresist layer having photosensitivity.

  Then, for example, a step of performing immersion exposure on the photoresist layer from the top of the resist protective layer through pre-baking and cooling, and then dissolving the resist protective layer in an alkaline aqueous solvent through post-exposure bake (PEB) and cooling And removing it.

  Here, the resist protective layer is formed as a resin having a linear or cyclic aliphatic structural unit, the aliphatic structural unit constituting the resin forming the resist protective layer, the hydrophilic functional group described above, It is formed by introducing an atom or atomic group such as fluorine that improves the affinity between the resist protective layer and the fluorine-based organic solvent or alkaline aqueous solvent, and an atom or atomic group such as an adamantyl group that stabilizes the resist protective layer. Is possible.

  FIG. 13 is a process diagram showing a conventional immersion exposure method. As apparent from FIGS. 12 and 13, in the immersion exposure method according to the present invention, in addition to applying a resist protective material with, for example, a fluorine-based organic solvent that does not dissolve the photoresist layer, resist protection with an alkaline aqueous solvent is performed. Since the photoresist layer can be developed simultaneously with the dissolution and removal of the layer, the immersion exposure can be performed without taking any special effort to remove the resist protective layer.

  As described in the above embodiments, according to the laminated structure for immersion exposure according to the present invention, at least partly overlaps with the photosensitive wavelength band of the photoresist layer in the immersion exposure for exposing the photoresist layer. Since the resist protective layer having a transmitted light wavelength band is formed on the photoresist layer with a resin having a linear or cyclic aliphatic structural unit, for example, an ArF excimer laser having a central wavelength of 193 nm is used as an exposure light source. Also in the immersion exposure method, formation of a poorly soluble layer in the photoresist layer and occurrence of abnormal resist shape can be suppressed.

  That is, the high refractive index medium interposed between the projection lens and the object to be exposed, for example, pure water enters the photoresist layer, and the acid generator that constitutes the photoresist layer into the pure water and the acid generator are generated during exposure. Acid outflow can be avoided by the presence of a resist protective layer formed on the photoresist layer, and by suppressing the formation of a locally poorly soluble layer, the immersion exposure method can function more effectively. It was possible to form a resist pattern.

  In addition, by introducing a polar atom such as fluorine (F) into the aliphatic structural unit of the resist protective layer, the affinity for a polar solvent such as a fluorine-based organic solvent is selectively improved and the stability against other organic solvents is increased. Is improved. Furthermore, by combining with the introduction of a hydrophilic functional group such as a carbonyl group, a sulfone group, a hydroxyl group, or a carboxyl group, it can be configured to dissolve only in a fluorine-based organic solvent and an alkaline aqueous solvent.

  Therefore, according to the immersion exposure method of the present invention, the resist protective layer is formed by applying a resist protective material by using a highly polar solvent typified by a fluorine-based organic solvent. Occasionally dissolution of the photoresist layer can be avoided. Furthermore, since the resist protective layer is peeled off with an alkaline aqueous solvent such as a 2.38% TMAH (tetramethylammonium hydroxide) aqueous solution, the photoresist layer can be simultaneously developed. The process efficiency is improved, and semiconductor devices and electronic devices can be supplied more quickly in response to market demands.

  Further, according to the laminated structure for immersion exposure and the immersion exposure method according to the present invention, the resist protective layer is an antireflection functional layer (TARC), and has a refractive index different from that of the photoresist layer, for example. For example, by adjusting the thickness, it is possible to reduce variations in the pattern line width due to the thickness of the photoresist layer, resulting from the standing wave effect based on multiple interference in the photoresist layer. .

In addition, according to the method for manufacturing an electronic device according to the present invention, it is possible to simplify the manufacture of various devices and improve the mass productivity by introducing the above-described immersion exposure method to manufacture the electronic device. Furthermore, the environmental load in manufacturing can be reduced by reducing the number of processes.
The electronic device according to the present invention is an electronic device having a fine structure portion obtained by the method for manufacturing an electronic device including the immersion exposure method according to the present invention, wherein the fine structure is generated by the generation of particles in the peeling of the resist protective layer. The occurrence of defects in the portion is avoided, the yield is ensured, and the reliability is improved.

The laminated structure for immersion exposure, the immersion exposure method, the method for manufacturing an electronic device, and the electronic device according to the present invention are not limited to the above-described embodiments.
For example, in the above-described embodiment, an example in which pure water is used as a high refractive index medium for immersion exposure has been described, but various media including neutral to acidic aqueous solvents are used as the high refractive index medium. The present invention can be variously modified and modified such that it can be used.

1A and 1B are a schematic diagram showing a laminated structure for immersion exposure according to the present invention, and a schematic diagram showing a molded shape of a photoresist obtained by exposure to the laminated structure for immersion exposure. 2A and 2B are schematic views showing an example of acid movement between the photoresist layer and the resist protective layer in the laminated structure for immersion exposure, and a schematic view showing a molded shape of the photoresist formed based on this. It is. FIG. 3A and FIG. 3B are schematic views illustrating an acrylic structural unit as an example of an aliphatic structural unit that constitutes the resin that forms the laminated structure for immersion exposure according to the present invention. 4A and 4B are schematic views showing an example of the structure of a side chain in an acrylic structural unit as an example of an aliphatic structural unit that constitutes a resin that forms a laminated structure for immersion exposure according to the present invention. . FIG. 5A and FIG. 5B are schematic diagrams showing an example of a side chain structure in an acrylic constituent unit as an example of an aliphatic constituent unit constituting the resin forming the laminated structure for immersion exposure according to the present invention. . 6A and 6B exemplify a COMA (cycloolefin / maleic anhydride copolymer) -based structural unit as an example of an aliphatic structural unit that constitutes a resin that forms the laminated structure for immersion exposure according to the present invention. It is a schematic diagram. FIG. 7A and FIG. 7B are schematic views illustrating a cycloolefin-based structural unit as an example of an aliphatic structural unit that constitutes the resin that forms the laminated structure for immersion exposure according to the present invention. FIG. 2 is a schematic view illustrating a VEMA (vinyl ether / maleic anhydride copolymer) -based structural unit as an example of an aliphatic structural unit that constitutes the resin forming the laminated structure for immersion exposure according to the present invention. FIG. 9A and FIG. 9B show a COMA (cycloolefin / maleic anhydride copolymer) system unit and an acrylic system as an example of an aliphatic system unit that constitutes the resin that forms the laminated structure for immersion exposure according to the present invention. It is a schematic diagram which illustrates a structural unit. It is the schematic which shows the fluctuation | variation of the thickness of the photoresist layer by a board | substrate shape, ie, a process level | step difference. FIG. 11A and FIG. 11B are a schematic diagram showing the principle of reduction of multiple interference and standing wave in the exposure of the photoresist layer, and the variation of the resist line width due to multiple interference and standing wave and the result of the reduction, respectively. It is a schematic diagram shown. It is process drawing which shows an example of the immersion exposure method by this invention. It is process drawing which shows an example of the conventional liquid immersion exposure method. 14A and 14B are a schematic diagram showing the configuration of an example of an immersion exposure apparatus and a schematic diagram showing the principle of immersion exposure. It is the schematic which shows the shaping | molding shape of the photoresist layer obtained by the conventional immersion exposure method.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Laminated structure for immersion exposure, 2 ... Substrate, 3 ... Photoresist layer, 4 ... Resist protective layer, 11 ... Acrylic structural unit, 12 ... COMA (cycloolefin -Maleic anhydride copolymer) system unit, 13 ... cycloolefin system unit, 14 ... VEMA (vinyl ether / maleic anhydride copolymer) system unit, 22 ... substrate, 23 ... Photoresist layer 31 ... Immersion exposure method 101 ... Immersion exposure apparatus 102 ... Substrate 103 ... Photoresist layer 131 ... Conventional immersion exposure method

Claims (40)

A laminated structure for immersion exposure in which exposure is performed by interposing a high refractive index medium between an exposure projection lens and an exposure target;
The exposure object is a photoresist layer, a resist protective layer is formed on the photoresist layer,
The photosensitive wavelength band of the photoresist layer is a short wavelength region of 193 nm or less,
The photosensitive wavelength band of the photoresist layer and the transmitted light wavelength band of the resist protective layer are configured to overlap at least partially,
Layered structure for immersion exposure, wherein the resist protective layer is a resin having a linear or cyclic aliphatic structural unit and is soluble only in a fluorine-based organic solvent and an alkaline aqueous solvent .   The laminated structure for immersion exposure according to claim 1, wherein the resist protective layer is configured not to dissolve, penetrate or swell in a neutral or acidic aqueous solvent.   2. The laminated structure for immersion exposure according to claim 1, wherein the high refractive index medium is a neutral or acidic aqueous solvent.   The laminated structure for immersion exposure according to claim 1, wherein the aliphatic structural unit has a hydrophilic functional group.   The laminated structure for immersion exposure according to claim 4, wherein the aliphatic structural unit has at least one of a carbonyl group, a sulfone group, a hydroxyl group, and a carboxyl group as the hydrophilic functional group. .   The laminated structure for immersion exposure according to claim 1, wherein the aliphatic structural unit has an atom or an atomic group that stabilizes the resist protective layer.   2. The immersion exposure according to claim 1, wherein the aliphatic constituent unit has an atom or an atomic group that improves the affinity between the resist protective layer and the fluorinated organic solvent or the alkaline aqueous solvent. Laminated structure.   The aliphatic constituent unit is an acrylic constituent unit, a COMA (cycloolefin / maleic anhydride copolymer) constituent unit, a cycloolefin constituent unit, or a VEMA (vinyl ether / maleic anhydride copolymer) constituent unit. The laminated structure for immersion exposure according to claim 1, wherein at least one kind is used.   The laminated structure for immersion exposure according to claim 1, wherein the resist layer is made of a chemically amplified resist.   2. The laminated structure for immersion exposure according to claim 1, wherein the resist protective layer is a layer having an antireflection function (TARC: Top Anti Reflective Coating). An immersion exposure method for performing exposure by interposing a high refractive index medium between an exposure projection lens and an exposure target,
The exposure object is a photoresist layer,
The photosensitive wavelength band of the photoresist layer is a short wavelength region of 193 nm or less,
The photosensitive wavelength band of the photoresist layer and the transmitted light wavelength band of the resist protective layer are configured to overlap at least partially,
Applying a resist protective material dissolved in a fluorine-based organic solvent on the photoresist layer, and forming a resist protective layer by removing the fluorine-based solvent;
Performing immersion exposure on the photoresist layer from above the resist protective layer;
And removing the resist protective layer by dissolving in an alkaline aqueous solvent,
An immersion exposure method, wherein the resist protective layer is formed as a resin having a linear or cyclic aliphatic structural unit.   The immersion exposure method according to claim 11, wherein the resist protective layer is configured not to dissolve, penetrate, or swell in a neutral or acidic aqueous solvent.   12. The immersion exposure method according to claim 11, wherein the high refractive index medium is a neutral or acidic aqueous solvent.   The immersion exposure method according to claim 11, wherein the aliphatic structural unit has a hydrophilic functional group.   15. The immersion exposure method according to claim 14, wherein the aliphatic structural unit has at least one of a carbonyl group, a sulfone group, a hydroxyl group, and a carboxyl group as the hydrophilic functional group.   The immersion exposure method according to claim 11, wherein the aliphatic structural unit has an atom or an atomic group that stabilizes the resist protective layer.   The immersion exposure according to claim 11, wherein the aliphatic structural unit has an atom or an atomic group that improves the affinity between the resist protective layer and the fluorine-based organic solvent or the alkaline aqueous solvent. Method.   The aliphatic constituent unit is an acrylic constituent unit, a COMA (cycloolefin / maleic anhydride copolymer) constituent unit, a cycloolefin constituent unit, or a VEMA (vinyl ether / maleic anhydride copolymer) constituent unit. The immersion exposure method according to claim 11, comprising at least one kind.   12. The immersion exposure method according to claim 11, wherein the resist layer is made of a chemically amplified resist.   12. The immersion exposure method according to claim 11, wherein the resist protective layer is a layer having an antireflection function (TARC: Top Anti Reflective Coating). A method of manufacturing an electronic device having a photolithography process,
The photosensitive wavelength band of the photoresist layer is a short wavelength region of 193 nm or less,
The photosensitive wavelength band of the photoresist layer and the transmitted light wavelength band of the resist protective layer are configured to overlap at least partially,
In the photolithography step, a step of applying a resist protective material dissolved in a fluorine-based organic solvent on the photoresist layer, and forming a resist protective layer by removing the fluorine-based solvent;
A step of performing immersion exposure on the photoresist layer by interposing a high refractive index medium between the projection lens for exposure and the resist protective layer;
And removing the resist protective layer by dissolving in an alkaline aqueous solvent,
A method of manufacturing an electronic device, wherein the resist protective layer is formed as a resin having a linear or cyclic aliphatic structural unit.   The method of manufacturing an electronic device according to claim 21, wherein the resist protective layer is configured not to dissolve, penetrate, or swell in a neutral or acidic aqueous solvent.   The method of manufacturing an electronic device according to claim 21, wherein the high refractive index medium is a neutral or acidic aqueous solvent.   The method for manufacturing an electronic device according to claim 21, wherein the aliphatic structural unit has a hydrophilic functional group.   25. The method for manufacturing an electronic device according to claim 24, wherein the aliphatic structural unit has at least one of a carbonyl group, a sulfone group, a hydroxyl group, and a carboxyl group as the hydrophilic functional group.   The method for manufacturing an electronic device according to claim 21, wherein the aliphatic structural unit has an atom or an atomic group that stabilizes the resist protective layer.   The electronic device according to claim 21, wherein the aliphatic constituent unit has an atom or an atomic group that improves the affinity between the resist protective layer and the fluorine-based organic solvent or the alkaline aqueous solvent. Production method.   The aliphatic constituent unit is an acrylic constituent unit, a COMA (cycloolefin / maleic anhydride copolymer) constituent unit, a cycloolefin constituent unit, or a VEMA (vinyl ether / maleic anhydride copolymer) constituent unit. The method for manufacturing an electronic device according to claim 21, comprising at least one kind.   The method of manufacturing an electronic device according to claim 21, wherein the resist layer is made of a chemically amplified resist.   The method of manufacturing an electronic device according to claim 21, wherein the resist protective layer is a layer having a reflection preventing function (TARC; Top Anti Reflective Coating). An electronic device having a microstructure part,
A resist protective layer is formed on the photoresist layer as a resin having a linear or cyclic aliphatic structural unit,
The photosensitive wavelength band of the photoresist layer is a short wavelength region of 193 nm or less,
The photosensitive wavelength band of the photoresist layer and the transmitted light wavelength band of the resist protective layer are configured to overlap at least partially,
The resist layer is exposed by immersion exposure with a high refractive index medium interposed between the projection lens for exposure and the resist protective layer,
An electronic device having a microstructure part, wherein the resist layer and the resist protective layer are formed by a pattern in which both of the resist layer and the resist protective layer are removed by an alkaline aqueous solvent or by processing using the pattern.   32. The electronic device according to claim 31, wherein the resist protective layer is configured not to dissolve, penetrate, or swell in a neutral or acidic aqueous solvent.   32. The electronic device according to claim 31, wherein the high refractive index medium is a neutral or acidic aqueous solvent.   32. The electronic device according to claim 31, wherein the aliphatic structural unit has a hydrophilic functional group.   The semiconductor device according to claim 34, wherein the aliphatic structural unit has at least one of a carbonyl group, a sulfone group, a hydroxyl group, and a carboxyl group as the hydrophilic functional group.   32. The electronic device according to claim 31, wherein the aliphatic structural unit has an atom or an atomic group that stabilizes the resist protective layer.   32. The electronic device according to claim 31, wherein the aliphatic structural unit has an atom or an atomic group that improves the affinity between the resist protective layer and the fluorinated organic solvent or the alkaline aqueous solvent.   The aliphatic constituent unit is an acrylic constituent unit, a COMA (cycloolefin / maleic anhydride copolymer) constituent unit, a cycloolefin constituent unit, or a VEMA (vinyl ether / maleic anhydride copolymer) constituent unit. 32. The electronic device according to claim 31, comprising at least one kind.   32. The electronic device according to claim 31, wherein the resist layer is made of a chemically amplified resist.   32. The electronic device according to claim 31, wherein the resist protective layer is a layer having an antireflection function (TARC: Top Anti Reflective Coating).

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