JP2012109322A - Pattern formation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pattern formation method which efficiently forms a pattern in an imperfect shot region, improves throughput, and accurately forms the pattern.SOLUTION: A first pattern is formed by forming a first film on a first region on a processed film formed on a substrate and conducting patterning on the first film. Then, after the first pattern is formed, an adhesion film is formed on the processed film so as not to change the size of the first pattern. Subsequently, a second pattern is formed on the adhesion layer of a second region on the processed film which is different from the first region by using an imprint method. Next, the processed film is etched using the first pattern and the second pattern as masks.

Description

  Embodiments relate to a pattern forming method.

  Optical lithography has been used to form a desired pattern in semiconductor device formation. In conventional photolithography, resolution has been improved by shortening the exposure wavelength of an exposure apparatus, and wafer processing speed has been improved. On the other hand, the size of the exposure apparatus and the cost for acquiring the apparatus are significantly increased. For this reason, imprint lithography is expected as a lithographic means that can be more inexpensive and can exhibit high resolution.

  Imprint lithography is a technique for forming a desired pattern formed on a template on a substrate by pressing a resin material onto the substrate using a mold called a template on which a desired pattern is formed in advance. As a technique for fixing the shape of the resin material formed with the template, there are thermal imprint lithography in which the resin is cured by heat and optical imprint lithography in which the resin is cured by irradiating energy rays such as UV light. The cured resin pattern is in close contact with the substrate and needs to be removed from the template.

  Since the semiconductor substrate has a circular shape, there are shots (hereinafter referred to as chipped shots) in which the transfer pattern region is included only incompletely even when the substrate is enlarged and the curvature is lowered. These chip shots are performed in order to prevent a processing difference depending on the pattern density in an etching process using a resist pattern formed in the lithography process as a mask and a subsequent CMP process.

JP2008-210877

  Provided is a pattern forming method capable of efficiently forming a pattern in a chipped shot region, improving the throughput, and forming the pattern with high accuracy.

  In the pattern transfer method according to one embodiment of the present invention, the first pattern is formed by forming and patterning the first film in the first region on the film to be processed formed over the substrate. Then, after forming the first pattern, an adhesion film is formed on the film to be processed so that the dimension of the first pattern does not vary. Next, a second pattern is formed on the adhesion layer in a second region on the workpiece film different from the first region by using an imprint method. Next, the film to be processed is etched using the first pattern and the second pattern as a mask.

It is the top view which showed an example showing the ratio of the missing shot in all the shots with respect to a circular-shaped semiconductor substrate. It is a figure showing the flow of the pattern formation method concerning Example 1 of this invention. It is sectional drawing which showed the flow shown in FIG. 2 typically. It is the perspective view which showed the method of exposing concentrically, rotating a board | substrate with respect to a chipping shot area | region. It is sectional drawing which showed the flow shown in FIG. 2 typically. It is sectional drawing which showed the flow shown in FIG. 2 typically. It is a figure showing the flow of the pattern formation method concerning Example 2 of this invention. FIG. 8 is a cross-sectional view schematically showing the flow shown in FIG. 7. FIG. 8 is a cross-sectional view schematically showing the flow shown in FIG. 7. FIG. 8 is a cross-sectional view schematically showing the flow shown in FIG. 7. It is a figure showing the flow of the pattern formation method concerning Example 3 of this invention. It is a figure showing the flow of the pattern formation method concerning Example 4 of this invention. It is sectional drawing which showed the flow shown in FIG. 12 typically. It is sectional drawing which showed the flow shown in FIG. 12 typically.

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

  FIG. 1 shows an example of the ratio of missing shots in all shots to a circular semiconductor substrate. Since the missing shot includes an incomplete region necessary for device operation, it is not necessary to form a resist pattern by a lithography process. However, in an element region etching process or a CMP (Chemical Mechanical Polishing) process, a processing difference due to a rapid change in pattern density occurs in the element region adjacent to the chip shot portion. A resist pattern is also formed on the shot portion.

  Since a pattern is formed in the chipped shot portion from the viewpoint of suppressing processing differences and the like, it is not necessary to form a fine pattern equivalent to the element region. Therefore, if the pattern formation can be replaced by other inexpensive means, the resist material necessary for forming the fine pattern can be suppressed and the throughput can be improved.

  FIG. 2 shows a flow of the pattern forming method according to the first embodiment of the present invention. 3, FIG. 5 and FIG. 6 are cross-sectional views schematically showing the flow shown in FIG. 3, 5, and 6 show the element region and the missing shot region adjacent to each other for convenience, the present invention is not limited to this.

  First, as shown in FIG. 3A, a base layer 2 to be processed is formed on a substrate 1 (step 1). The underlayer 2 is formed in both the element region and the chip shot region. As shown in FIG. 3B, a negative resist film 3 is applied on the underlayer 2 by using, for example, spin coating (step 1). In addition to spin coating, it may be applied using a slit type nozzle or a roller. After applying the negative resist film 3, an appropriate heating process (PAB: Post Applied Bake) may be performed as necessary. The heating process is performed mainly for the purpose of removing unnecessary solvents from the negative resist film 3 formed by coating.

  Subsequently, as shown in FIG. 3C, a patterned energy beam is irradiated to the negative resist film 3 formed in the chipped shot region which is the outer peripheral region of the substrate 1 to form a latent image 4. (Step 2). When the coverage of a resist pattern formed in an element region to be described later is C%, it is desirable that the ratio of the energy irradiation portion to the negative resist film 3 in the missing shot region is approximately C%. The pattern formed in the missing shot region does not need to be a periodic arrangement within one shot, and may be a pattern arrangement different for each shot, such as an arrangement that is point-symmetric with respect to the center of the substrate 1. In addition, you may perform the post-exposure heating process (PEB: Post Exposure Bake) as needed with respect to the negative resist film 3 irradiated with the energy beam.

  The lithography of the lack shot region only needs to be able to adjust the coverage, and does not require the formation of a fine pattern equivalent to the element region. Therefore, in order to reduce the manufacturing cost, the exposure light used in the advanced lithography process such as the I-line wavelength is used. It is preferable to use light having a long wavelength. Further, for example, a naphthoquinonediazide-based novolak resist can be used as an example of an I-line resist.

  Examples of a method for forming a resist pattern having a point-symmetric arrangement with respect to the center of the substrate 1 include the following methods. As shown in FIG. 4, the missing shot area is exposed concentrically while rotating the substrate 1 by a light source 5 such as an electron beam, DUV (Deep Ultra Violet) light, or a mercury lamp. At that time, a shot map type aperture mask 6 is disposed on the substrate 1 so that the element region is not exposed. For example, when it is necessary to achieve a resist coverage of 50%, a spot beam with a width of 0.5 μm is exposed at an interval of 0.5 μm at a rotation speed of the substrate of 2000 rpm, and an exposure in a missing shot area with a width of 2 mm in 60 seconds. Is possible. By installing a plurality of spot beams, the throughput can be improved.

  Next, as shown in FIG. 5A, the negative resist film 3 on which the latent image 4 is formed is subjected to a development process using a predetermined developer, and the negative resist film 3 dissolved in the developer is removed. A predetermined resist pattern is obtained by carrying out a rinsing process to be removed (step 3). The coverage of the resist pattern in the chipped shot region is approximately C%. In this embodiment, since a negative resist is used, a resist pattern remains in a region irradiated with an exposure amount greater than or equal to a predetermined amount, and a resist film is removed in a region where an exposure amount such as an unexposed portion is less than or equal to a predetermined amount. Therefore, as shown in FIG. 5A, since the element region is not exposed, a resist pattern is not formed.

  After the development process, a heating process may be performed on the resist pattern as necessary. In general, the purpose of the heating step after development is to remove moisture. In addition, the solvent resistance of the resist pattern can be increased by heating after development. In order to increase the solvent resistance of the resist pattern more positively, it is preferable to perform high-temperature heating at 200 ° C. or higher. Further, in order to further improve the solvent resistance, when heating at 250 ° C. or higher, the resist pattern is oxidatively decomposed by oxygen in the atmosphere, so heating in a low oxygen atmosphere such as a nitrogen atmosphere is performed. Is desirable. Further, the resist pattern may shrink due to the treatment for improving the solvent resistance. In such a case, the exposure amount of the resist pattern in the missing shot region is such that the coverage of the resist pattern in the missing shot region after shrinkage is approximately C% with respect to the coverage C% of the resist pattern in the element region. Alternatively, it is desirable to adjust the exposure amount and the photomask dimension. In this embodiment, a process for increasing the solvent resistance of the resist pattern is performed (step 4).

In addition to improving the solvent resistance of the resist pattern by the above-described post-development heating step, a process for increasing the solvent resistance of the resist pattern may be performed as necessary. Examples of the solvent resistance treatment include UV (Ultraviolet) irradiation, UV cure, EB (Electron Beam) irradiation, EB cure, ion implantation, and plasma treatment. The irradiation amount of UV light of UV irradiation or UV cure is preferably 300 mJ / cm ² or more, and the EB irradiation amount of EB irradiation or EB cure is preferably 0.1 C / cm ² or more. When performing the UV cure or EB cure while heating the resist pattern to 180 degrees or more, it is desirable to carry out in a low oxygen atmosphere such as a nitrogen atmosphere or a vacuum atmosphere. In the case of ion implantation, for example, in the case of Ar ion implantation, it is desirable that the implantation amount is 1 × 10 ¹¹ to 1 × 10 ¹³ at 1 to 30 keV.

  Next, as shown in FIG. 5B, an adhesion film 7 used for imprint lithography is formed on the entire surface of the substrate 1 (step 5). The adhesion film 7 is formed on the underlying layer 2 on the element region, on the foundation layer 2 on the chipped shot region, and on the negative resist film 3, but the adhesion film 7 on the chipped shot region is formed conformally. Is desirable. The adhesion film 7 is formed by a method by coating film formation, a reaction formation method by gas phase, or the like.

  Imprint lithography is gaining expectations as a leading-edge and low-cost lithography process, but the resist pattern collapses when the template is separated from the imprint resist because the imprint resist and the template are in physical contact. Defects such as tearing are likely to occur. Therefore, before the imprint lithography is performed, the adhesion film 7 is formed in order to improve the adhesion between the imprint resist and the base and suppress defects. The adhesion film 7 can be formed by, for example, spin coating.

  Before the adhesion film 7 is formed, a resist pattern is already formed in the missing shot region. If the solvent resistance of the resist pattern formed in the chipped shot region is low, the resist pattern formed in the chipped shot region may be deformed by the solvent used when forming the adhesion film 7. Is preferably applied to the resist pattern in the chipped shot region. For the formation of the adhesion film 7, for example, a silylating agent that is a gas or a liquid at room temperature can be used.

  Subsequently, as shown in FIG. 5C, an imprint resist pattern 8 is formed by imprint lithography on the element region where the adhesion film 7 is formed (step 6). In the imprint lithography, it is possible to selectively supply an imprint resist on the substrate 1 by using an ink jet or the like. Resist supply and pattern formation can be performed.

  In imprint lithography, in order to prevent destruction of a template and to prevent gas from remaining when a resin material is embedded in a pattern portion, it is common to leave a remaining film below and between patterns. Therefore, in order to transfer the imprint resist pattern 8 to the underlayer 2, first, the remaining film must be processed. The remaining film portion is substantially the same material as the imprint resist pattern 8, and the etching rate is also substantially the same. When the coverage of the imprint resist pattern 8 is C%, the coverage of the missing shot region is also set to approximately C% as described above, so that the coverage of the entire wafer is approximately C%.

Next, as shown in FIG. 6A, the remaining film between the imprint resist pattern 8 and the adhesion film 7 are processed and removed by etching (step 7). In the etching process for processing the remaining film and the adhesion film 7, the adhesion film 7 on the resist pattern formed in the chipped shot region and the resist pattern itself formed in the chipped shot region are also processed. When the etching rate of the imprint resist and the resist formed in the chipped shot region is substantially the same, the resist film thickness (T _edge ) formed in the chipped shot region is the pattern of the imprint resist pattern 8. It is desirable to be equal to or greater than the sum of height (T _center ) and residual film thickness (RLT). For etching the remaining film of the imprint resist pattern 8, it is desirable to use an oxygen-based or halogen-based etching gas.

When a resist pattern is formed on the chipped shot region by photolithography, the development process is performed as described above. In the developing process, the film thickness is reduced even in the remaining pattern portion. In the case of a positive resist, even if the exposure amount is completely zero, the solubility in the developer is not completely zero. In the case of a negative resist, even if the exposure amount is sufficiently large, similarly to the developer. The solubility is rarely zero. Further, since only light of a finite diffraction order contributes to the image formation, the optical image irradiated to the resist film by photolithography has only a finite contrast. For this reason, the resist coating film thickness in the case of forming a resist pattern by photolithography on the chipped shot portion is considered to be the pattern height (T _center ) of the imprint resist pattern 8 in the element region in consideration of the film thickness reduction by development. It is more desirable to make it thicker than the total of the residual film thickness (RLT).

  Next, as shown in FIG. 6B, the base layer 2 is etched using the imprint resist pattern 8 in the element region and the pattern of the negative resist film 3 in the chip shot region as a mask to form a predetermined pattern. At this time, since the pattern coverage of the element region and the chipped shot region is made uniform at C%, variations in processing can be suppressed.

  Subsequently, as shown in FIG. 6C, a predetermined pattern is completed by removing the imprint resist pattern 8 in the element region and the pattern of the negative resist film 3 in the chipped shot region.

  As described above, in this embodiment, imprint lithography is used for pattern formation in the element region, and resist supply and pattern formation can be selectively performed in the element region. In imprint lithography, a fine resist pattern can be formed with high dimensional accuracy, but the processing speed is inferior to that of conventional optical lithography. The chip shot region is formed only to maintain the dimensional uniformity of the element region in the vicinity of the chip shot. The missing shot is formed in advance by another lithography means, in this embodiment, photolithography, and the element region that requires a fine and high-precision resist pattern is formed separately by imprint lithography. Each pattern can be formed efficiently. In addition, although the adhesion film 7 is formed prior to imprint lithography, the resist pattern in the missing shot region is subjected to a solvent resistance improving process in advance, so that pattern deformation in the missing shot region that occurs during the formation of the adhesion film is suppressed. Can do.

  FIG. 7 shows a flow of a pattern forming method according to the second embodiment of the present invention. The second embodiment is different from the first embodiment in that a positive resist is used to form a pattern of a missing shot region. The other parts are the same process as in the first embodiment, and the same reference numerals are used for the overlapping parts. 8 to 10 are cross-sectional views schematically showing the flow shown in FIG. 8 to 10 show the element region and the missing shot region adjacent to each other for convenience, but the present invention is not limited to this.

  First, as shown in FIG. 8A, a base layer 2 that is a film to be processed is formed on a substrate 1. The underlayer 2 is formed in both the element region and the chip shot region. As shown in FIG. 8B, a positive resist film 9 is applied on the underlying layer 2 by using, for example, spin coating (step 8). In addition to spin coating, it may be applied using a slit type nozzle or a roller. After applying the positive resist film 9, an appropriate heating process (PAB: Post Applied Bake) may be performed as necessary. The heating process is performed mainly for the purpose of removing unnecessary solvent from the positive resist film 9 formed by coating.

  Subsequently, as shown in FIG. 8C, a patterned energy beam is irradiated to the positive resist film 9 formed in the chipped shot region which is the outer peripheral region of the substrate 1 to form a latent image 4. . When the coverage of a resist pattern formed in an element region to be described later is C%, it is desirable that the ratio of the energy irradiation portion to the positive resist film 9 in the missing shot region is approximately 100-C%. The element region is irradiated on the entire surface with an exposure amount that completely dissolves the resist film in the development process, that is, with a coverage of 0% (step 9).

  When the positive resist film 9 is exposed using a photomask, a completely clear area mask with a coverage of C% is required. In a general photolithographic apparatus, the photomask replacement time takes several minutes. For this reason, it is desirable to divide one mask into an area with a coverage C% and a completely clear area, and assign them to the missing shot area and the complete shot area. In addition, you may implement the post-exposure heating process (PEB: Post Exposure Bake) as needed with respect to the positive resist film 9 irradiated with the energy beam.

  Next, as shown in FIG. 9A, the positive resist film 9 on which the latent image 4 is formed is subjected to a development process using a predetermined developer, and the positive resist film 9 dissolved in the developer is removed. A predetermined resist pattern is obtained by carrying out a rinsing process to be removed (step 10). The coverage of the resist pattern in the chipped shot region is approximately C%. In this embodiment, since a positive resist is used, the resist pattern dissolves in a region irradiated with a predetermined exposure amount or more, and a resist film remains in a region where the exposure amount such as an unexposed portion is a predetermined amount or less. Therefore, as shown in FIG. 9A, the entire surface of the element region is exposed and no resist pattern is formed.

  After the development process, a heating process may be performed on the resist pattern as necessary. In general, the purpose of the heating step after development is to remove moisture. In addition, the solvent resistance of the resist pattern can be increased by heating after development. In order to increase the solvent resistance of the resist pattern more positively, it is preferable to perform high-temperature heating at 200 ° C. or higher. Further, in order to further improve the solvent resistance, when heating at 250 ° C. or higher, the resist pattern is oxidatively decomposed by oxygen in the atmosphere, so heating in a low oxygen atmosphere such as a nitrogen atmosphere is performed. Is desirable. Further, the resist pattern may shrink due to the treatment for improving the solvent resistance. In such a case, the exposure amount of the resist pattern in the missing shot region is such that the coverage of the resist pattern in the missing shot region after shrinkage is approximately C% with respect to the coverage C% of the resist pattern in the element region. Alternatively, it is desirable to adjust the exposure amount and the photomask dimension. In this embodiment, a process for increasing the solvent resistance of the resist pattern is performed (step 11).

In addition to improving the solvent resistance of the resist pattern by the above-described post-development heating step, a process for increasing the solvent resistance of the resist pattern may be performed as necessary. Examples of the solvent resistance treatment include UV (Ultra Violet) irradiation, UV cure, EB (Electron Beam) irradiation, EB cure, ion implantation, and plasma treatment. The irradiation amount of UV light of UV irradiation or UV cure is preferably 300 mJ / cm ² or more, and the EB irradiation amount of EB irradiation or EB cure is preferably 0.1 C / cm ² or more. When performing the UV cure or EB cure while heating the resist pattern to 180 degrees or more, it is desirable to carry out in a low oxygen atmosphere such as a nitrogen atmosphere or a vacuum atmosphere. In the case of ion implantation, for example, in the case of Ar ion implantation, it is desirable that the implantation amount is 1 × 10 ¹¹ to 1 × 10 ¹³ at 1 to 30 keV.

  Next, as shown in FIG. 9B, an adhesion film 7 used for imprint lithography is formed on the entire surface of the substrate 1 (step 12). The adhesion film 7 is formed on the underlying layer 2 on the element region, on the foundation layer 2 on the chipped shot region, and on the positive resist film 9, but the adhesion film 7 on the chipped shot region is formed conformally. Is desirable. The adhesion film 7 is formed by a method by coating film formation, a reaction formation method by gas phase, or the like.

  Before the adhesion film 7 is formed, a resist pattern is already formed in the missing shot region. If the solvent resistance of the resist pattern formed in the chipped shot region is low, the resist pattern formed in the chipped shot region may be deformed by the solvent used when forming the adhesion film 7. Is preferably applied to the resist pattern in the chipped shot region. For the formation of the adhesion film 7, for example, a silylating agent that is a gas or a liquid at room temperature can be used.

  Subsequently, as shown in FIG. 9C, an imprint resist pattern 8 is formed by imprint lithography on the element region where the adhesion film 7 is formed (step 13). In the imprint lithography, it is possible to selectively supply an imprint resist on the substrate 1 by using an ink jet or the like. Resist supply and pattern formation can be performed.

  In imprint lithography, in order to prevent destruction of a template and to prevent gas from remaining when a resin material is embedded in a pattern portion, it is common to leave a remaining film below and between patterns. Therefore, in order to transfer the imprint resist pattern 8 to the underlayer 2, first, the remaining film must be processed. The remaining film portion is substantially the same material as the imprint resist pattern 8, and the etching rate is also substantially the same. When the coverage of the imprint resist pattern 8 is C%, the coverage of the missing shot region is also set to approximately C% as described above, so that the coverage of the entire wafer is approximately C%.

Next, as shown in FIG. 10A, the remaining film between the imprint resist patterns 8 and the adhesion film 7 are processed and removed by etching (step 14). In the etching process for processing the remaining film and the adhesion film 7, the adhesion film 7 on the resist pattern formed in the chipped shot region and the resist pattern itself formed in the chipped shot region are also processed. When the etching rate of the imprint resist and the resist formed in the chipped shot region is substantially the same, the resist film thickness (T _edge ) formed in the chipped shot region is the pattern of the imprint resist pattern 8. It is desirable to be equal to or greater than the sum of height (T _center ) and residual film thickness (RLT). For etching the remaining film of the imprint resist pattern 8, it is desirable to use an oxygen-based or halogen-based etching gas. For the same reason as in the first embodiment, it is more desirable to make it thicker than the sum of the pattern height (T _center ) and the residual film thickness (RLT) of the imprint resist pattern 8 in the element region.

  Next, as shown in FIG. 10B, the base layer 2 is etched using the imprint resist pattern 8 in the element region and the pattern of the negative resist film 3 in the chip shot region as a mask to form a predetermined pattern. At this time, since the pattern coverage of the element region and the chipped shot region is made uniform at C%, variations in processing can be suppressed.

  Subsequently, as shown in FIG. 10C, a predetermined pattern is completed by removing the imprint resist pattern 8 in the element region and the pattern of the positive resist film 9 in the missing shot region.

  As described above, in this embodiment, imprint lithography is used for pattern formation in the element region, and resist supply and pattern formation can be selectively performed in the element region. In imprint lithography, a fine resist pattern can be formed with high dimensional accuracy, but the processing speed is inferior to that of conventional optical lithography. The chip shot region is formed only to maintain the dimensional uniformity of the element region in the vicinity of the chip shot. The missing shot is formed in advance by another lithography means, in this embodiment, photolithography, and the element region that requires a fine and high-precision resist pattern is formed separately by imprint lithography. Each pattern can be formed efficiently. In addition, although the adhesion film 7 is formed prior to imprint lithography, the resist pattern in the missing shot region is subjected to a solvent resistance improving process in advance, so that pattern deformation in the missing shot region that occurs during the formation of the adhesion film is suppressed. Can do.

  FIG. 11 shows a flow of a pattern forming method according to the third embodiment of the present invention. The third embodiment is described above in that the variation in the size of the resist pattern formed in the chipped shot region is suppressed by changing the solution used when forming the adhesion layer 7 formed prior to the imprint lithography of the element region. Different from Example 1 and Example 2. Specifically, a solvent that does not dissolve the resist pattern formed in the chipped shot region is used. The other parts are the same process as in the first embodiment, and the same reference numerals are used for the overlapping parts. Since the process flow omits the solvent resistance treatment from Example 1 and Example 2, the description is omitted.

  As a solvent for the adhesion film, a hydrocarbon solvent having a prime number of 4 or more, an alcohol solvent having 6 to 10 carbon atoms, an ether solvent having an alkyl group having 4 to 10 carbon atoms, and a ketone having an alkyl group having 4 to 12 carbon atoms. By using a system solvent, an ester solvent having 7 to 12 carbon atoms, or a solvent substituted with such fluorine or fluorine, the adhesion film 5 is formed while suppressing the size of the resist pattern of the chip shot, and the imprint pattern is formed. It becomes possible to form.

  A hydrocarbon solvent having 4 or more prime atoms, an alcohol solvent having 6 to 10 carbon atoms, an ether solvent having an alkyl group having 4 to 10 carbon atoms, a ketone solvent having an alkyl group having 4 to 12 carbon atoms, and 7 carbon atoms. Specific examples of -12 ester solvents include 1-butyl alcohol, 2-butyl alcohol, isobutyl alcohol, tert-butyl alcohol, 1-pentanol, 2-pentanol, 3-pentanol, tert-amyl alcohol, Neopentyl alcohol, 2-methyl-1-butanol, 3-methyl-1-butanol, 3-methyl-3-pentanol, cyclopentanol, 1-hexanol, 2-hexanol, 3-hexanol, 2,3-dimethyl 2-butanol, 3,3-dimethyl-1-butanol, 3,3-dimethyl-2-butanol 2-diethyl-1-butanol, 2-methyl-1-pentanol, 2-methyl-2-pentanol, 2-methyl-3-pentanol, 3-methyl-1-pentanol, 3-methyl-2 -Pentanol, 3-methyl-3-pentanol, 4-methyl-1-pentanol, 4-methyl-2-pentanol, 4-methyl-3-pentanol, cyclohexanol and the like can be mentioned. The above is an example, and the present invention is not limited to these. A plurality of these may be used in combination.

FIG. 12 shows a flow of a pattern forming method according to the fourth embodiment of the present invention. In the fourth embodiment, instead of the optical lithography described in the first to third embodiments, a self-assembled film is selectively formed in the chipped shot region, and the spontaneous formation formed in the self-assembled film by a predetermined process. A material obtained by removing at least one of the ordered phases is used for forming a resist pattern in a chipped shot region. The other parts are the same process as in the first embodiment, and the same reference numerals are used for the overlapping parts. 13 and 14 are cross-sectional views schematically showing the flow shown in FIG. 13 and 14 show the element region and the missing shot region adjacent to each other for convenience, but the present invention is not limited to this.

A technique of utilizing a spontaneous ordered phase formed in a self-assembled film as a lithography pattern is recognized as DSA (Direct Self Assembly) lithography. The most prominent example of the self-assembled film is polystyrene-block-polymethyl methacrylate (PS-b-PMMA). This is a structure (block copolymer) in which one polystyrene and one polymethyl methacrylate are combined, whereas a normal styrene-methyl acrylate polymer is a structure in which styrene and ethyl methacrylate are randomly connected (random polymer).

In a film composed of such PS-b-PMMA, the PS phase and the PMMA phase have a predetermined structure and period in the film by cooling after predetermined heating at a temperature equal to or higher than the glass transition temperature of the film. This causes a phenomenon that spontaneously forms an ordered phase. This phenomenon is understood as that the resin in the film is easily reconfigured by heating above the glass transition point and takes a thermodynamically stable structure. By cooling after the ordered phase is formed in the film, the transition to the disordered structure is prevented and the ordered phase during heating is maintained. In other words, it is the same kind of phenomenon as transformation in alloys.

It is known to form various ordered structures depending on the molecular weight of the PS block, the molecular weight of the PMMA block, the temperature, the film thickness, the film in contact with the self-assembled film, etc., for example, the vertical lamellar structure, the vertical cylinder structure, A horizontal cylinder structure, a spherical structure, etc. can be mentioned. In general, in a specific structure, in order to obtain a desired pattern period and line width, the molecular weight of the PS block and the PMMA block needs to be specified, and the film thickness and heating conditions need to be optimized. The glass transition temperature varies depending on the type of block copolymer (molecular weight of PS block and PMMA block).

Moreover, it does not necessarily occur only with a block copolymer, but an ordered phase may be formed by a mixture of a block copolymer and a relatively low molecular weight polymer composed of only one of the block copolymers, or a mixture of polymers.

In the chipped shot focused on in the present embodiment, the problems are the coverage and the remaining film during etching of the phase to be processed. For this reason, the periodic orientation of the ordered phase does not necessarily have to be constant. Therefore, the random lamella structure shown in FIG. 13 can be used. In this embodiment, a random lamella structure using a PS-b-PMMA film will be described as an example.

First, as shown in FIG. 13A, a base layer 2 to be processed is formed on a substrate 1, and surface treatment for forming a lamellar structure by PS-b-PMMA on the base layer 2 is performed. To form the organic layer 10 (step 15).

  In this embodiment, an organic phase is formed on the surface of the substrate by supplying the silane coupling material in a gas phase while the substrate is heated at a predetermined temperature. As another means, a chemical solution dissolved in a silane coupling material in an organic solvent is rotated and reacted with the substrate surface by a predetermined heat treatment, and then an unreacted silane coupling material or an organic layer formed in multiple layers is formed. It may be removed to form a monomolecular organic layer 10. Among various methods known as the formation technology of the SAM (Self Assembled Monolayers) layer that is the organic layer 10 of one molecular layer, the reactivity with the substrate, the cost, and the ease of forming the ordered phase of PS-b-PMMA What is necessary is just to select a desirable method.

The organic layer 10 is not necessarily formed, but in the manufacture of semiconductor elements, the film type on the surface of the substrate may change for each process during manufacture. For this reason, it is effective in terms of process stabilization and reproducibility to perform a treatment for making the surface energy state constant by the surface treatment. The organic layer formed by the surface treatment is ideally one molecular layer, that is, 1 nm or less. Considering that the RLT formed by imprint lithography is at least 5 nm, the presence of the surface treatment layer is not a problem in etching the substrate to be processed.

  On the organic layer 10, as shown in FIG. 13B, a PS-b-PMMA film, which is a self-assembled film 11, is selectively formed on the chipped shot region of the substrate 1 (step 16). . As a selective formation method of the self-assembled film, means such as development of a liquid film such as roller coating, squeegee coating, and cap coating, and formation of a micro liquid film by ink jet (and heat treatment as necessary) are used. It is possible. After forming the coating film of the self-assembled film, heating for reducing the residual solvent may be performed as necessary. The heating process corresponding to PAB in this general optical lithography may be performed continuously with a heating process for forming an ordered phase, which will be described later.

  The presence of the residual solvent facilitates the movement of the resin and thus promotes the formation of the ordered phase. On the other hand, the formation of the ordered phase may vary due to the difference in the amount of residual solvent within the wafer surface. The heating step for causing the residual solvent to occur is desirably performed at a temperature of 80 to 130 ° C. in consideration of a decrease in the glass transition temperature due to the residual solvent.

Subsequently, as shown in FIG. 13C, the substrate 1 on which the self-assembled film 11 is formed is subjected to a heat treatment for forming an ordered phase. Although the optimal value of heating temperature changes with molecular weight, it implements in 180-250 degreeC in the range of 1 minute-30 minutes, for example. Desirably, the heating is in the range of 180 ° C to 210 ° C for 5 minutes or less. When the heating temperature is 200 ° C. or higher for 10 minutes or longer, it is preferable to perform heating in a low oxygen atmosphere of several ppm or less such as a nitrogen atmosphere in order to avoid the influence of thermal oxidation. In this embodiment, since PS-b-PMMA is used, phase separation is performed into the PS phase 12 and the PMMA phase 13 (step 17).

  Next, as shown in FIG. 14A, the self-assembled film 11 phase-separated into the PS phase 12 and the PMMA phase 13 is subjected to development processing for removing one of the phases (step 18). ). Development processing is roughly classified into two types of development processing. One is mainly dry development by dry etching or ashing using an oxygen-based gas, and the other is wet development using a chemical solution.

  In this embodiment, a case where Dry development is performed will be described. For dry development, for example, oxygen plasma / oxygen radical or the like can be used. Since the PS phase 12 has higher etching resistance by oxygen plasma / oxygen radicals than the PMMA phase 13, the PMMA phase 13 can be selectively removed. The organic layer 10 formed before the self-assembled film 11 is formed is removed during the development process.

The PS phase 12 is highly resistant to dry development by oxygen plasma / oxygen radicals or the like with respect to the PMMA phase 13, but the PS phase 12 is not etched at all, and therefore film loss occurs. The selection ratio in dry development of the PMMA phase 13 and the PS phase 12 is about 1.5 to 2. For this reason, when using Dry development, the pattern thickness (T _{edge_DryPS} ) of the PS phase 12 after Dry development, in particular, the pattern height (T _center ) and the remaining film thickness ( _RLT ) of the imprint resist pattern 8 described later. It is more desirable to make it thicker than the sum of

  In the case of performing wet development, it is desirable to use a polar solvent in order to leave the PS phase 12 that is hydrophobic and remove the PMMA phase 13 that is hydrophilic. Further, the PMMA phase 13 may be subjected to a treatment for improving solubility by increasing the hydrophilicity / decreasing the molecular weight when the main chain of the molecular structure is cleaved by EB, VUV (Vacuum Ultraviolet) light, or DUV (Deep Ultraviolet) light. Absent. In order to cut the PS block and the PMMA block, for example, an electron beam of 1 to 10 keV, VUV light having a wavelength of 172 nm, UV light having a wavelength of 193 nm, or the like may be irradiated before wet development. However, since the decomposition reaction by irradiation with these energy rays shows a crosslinking reaction as a competitive reaction, it is preferable to set an appropriate irradiation amount. In order to suppress the progress of the crosslinking reaction, the electron beam, VUV light, or UUV light may be irradiated while the wafer is cooled or kept at room temperature so that the temperature of the wafer during irradiation does not increase rapidly. desirable.

Also in the wet development, the pattern thickness (T _{edge_DryPS} ) of the PS phase 12 after development is _{equal to} the pattern height (T _center ) and the _remaining film of the imprint resist pattern 8 to be described later for the same reason as the dry development described above. It is more desirable to make it thicker than the total of the thickness (RLT: residual layer thickness).

  Wet developer types include solutions in which methyl isobutyl ketone (MIBK) and alcohols such as isopropyl alcohol (IPA) are mixed at about 1:10 to 7: 3, organic acids such as acetic acid and butyric acid, TMAH ( Organic alkalis such as tetramethylammonium hydroxide) and TBAH (tetrabutylammonium hydroxide) can be used. A surfactant may be added to the developer.

  Next, as shown in FIG. 14B, a solvent resistance treatment similar to that in Example 1 and 2 is applied to the substrate 1 on which the pattern of the PS phase 12 is formed in the chipped shot region by the development treatment, if necessary. Alternatively, as in Example 3, the imprint adhesive film 7 is formed using a solution that does not dissolve the PS phase 12 pattern as a solvent (step 19).

  Next, as shown in FIG. 14C, an imprint resist pattern 8 is formed on the adhesion film in the element region on the wafer (step 20). Thereafter, by using the imprint resist pattern 8 and the PS phase 12 pattern as a mask, the base layer 2 is etched to form a desired pattern with good dimensional control (step 21).

  As described above, in this embodiment, imprint lithography is used for pattern formation in the element region, and resist supply and pattern formation can be selectively performed in the element region. In imprint lithography, a fine resist pattern can be formed with high dimensional accuracy, but the processing speed is inferior to that of DSA lithography. The chip shot region is formed only to maintain the dimensional uniformity of the element region in the vicinity of the chip shot. The missing shot is formed in advance by another lithography means, DSA lithography in this embodiment, and the element area that requires a fine and highly accurate resist pattern is formed separately by imprint lithography, so that the missing shot area and the element area are formed. Each pattern can be formed efficiently.

  Note that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 Substrate 2 Underlayer 3 Negative resist film 4 Latent image 5 Light source 6 Shot map type aperture mask 7 Adhesion film 8 Imprint resist pattern 9 Positive resist film 10 Organic layer 11 Self-assembled film 12 PS phase 13 PMMA phase

Claims (6)

Forming a first film in a first region on a film to be processed formed on a substrate and patterning the first pattern; and
Forming an adhesion film on the film to be processed so that the dimension of the first pattern does not change after forming the first pattern;
Forming a second pattern using an imprint method on the adhesion layer in a second region on the film to be processed different from the first region;
And a step of etching the film to be processed using the first pattern and the second pattern as a mask.   The pattern forming method according to claim 1, wherein in the step of forming the adhesion film, the adhesion film is formed using a solution that does not dissolve the first pattern.   The pattern forming method according to claim 1, wherein in the step of forming the adhesion film, the adhesion film is formed after performing a process for improving the solvent resistance of the first pattern.   The pattern forming method according to claim 1, wherein the first pattern is formed point-symmetrically with respect to a center of the substrate.   5. The pattern forming method according to claim 4, wherein the first pattern is formed by irradiating the substrate with energy rays through a shot map type mask while rotating the substrate.   4. The first pattern according to claim 1, wherein the first pattern is formed by removing at least one of two or more phases formed by phase separation of the self-assembled film. The pattern forming method according to item.

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