JP5206974B2 - Pattern formation method - Google Patents

Description

  In particular, the present invention exposes a grid-like mask pattern having different line widths, forms dense and isolated positive dot patterns by development, makes the pattern insoluble in solvents and alkali-soluble by acid and heat, In pattern formation using positive / negative reversal, in which a film for reversal slightly dissolved in alkali is applied and the surface layer portion of the film and the positive pattern are dissolved by alkali development to form a negative pattern, dense holes and isolated holes Is formed at the same time by one exposure.

In recent years, with the higher integration and higher speed of LSIs, there is a demand for finer pattern rules. In light exposure currently used as a general-purpose technology, the intrinsic resolution limit derived from the wavelength of the light source Is approaching. As exposure light used for forming a resist pattern, light exposure using g-ray (436 nm) or i-line (365 nm) of a mercury lamp as a light source was widely used in the 1980s. As a means for further miniaturization, the method of shortening the exposure wavelength is effective, and mass production after 64 Mbit (process size is 0.25 μm or less) DRAM (Dynamic Random Access Memory) in the 1990s In the process, a KrF excimer laser (248 nm) having a short wavelength was used as an exposure light source instead of i-line (365 nm). However, in order to manufacture DRAMs with a density of 256M and 1G or more that require finer processing technology (processing dimensions of 0.2 μm or less), a light source with a shorter wavelength is required, and an ArF excimer has been used for about 10 years. Photography using a laser (193 nm) has been studied in earnest. Initially, ArF lithography was supposed to be applied from the device fabrication of the 180 nm node, but KrF excimer lithography was extended to 130 nm node device mass production, and full-scale application of ArF lithography is from the 90 nm node. Further, a 65 nm node device is being studied in combination with a lens whose NA is increased to 0.9. For the next 45 nm node device, the exposure wavelength has been shortened, and F ₂ lithography with a wavelength of 157 nm was nominated. However, the cost of the scanner is increased by using a large amount of expensive CaF ₂ single crystal for the projection lens, the optical system is changed due to the introduction of the hard pellicle because the durability of the soft pellicle is extremely low, and the etching resistance of the resist film is reduced. Due to various problems, it has been proposed to advance F ₂ lithography and early introduction of ArF immersion lithography (Non-patent Document 1: Proc. SPIE Vol. 4690 xxix (2002)).

  In ArF immersion lithography, it has been proposed to impregnate water between the projection lens and the wafer. The refractive index of water at 193 nm is 1.44, and pattern formation is possible even with a lens having an NA (numerical aperture) of 1.0 or more. Theoretically, the NA can be increased to near 1.44. Initially, it was pointed out that the resolution was deteriorated and the focus shifted due to the change in refractive index accompanying the change in water temperature. It was confirmed that the water temperature was controlled within 1/100 ° C. and the influence of the heat generated from the resist film due to exposure was almost no worry, and the problem of refractive index change was solved. It was feared that microbubbles in the water could be transferred to the pattern, but it was confirmed that the water was sufficiently degassed and that there was no risk of bubble formation from the resist film due to exposure. In the early stage of immersion lithography in the 1980s, a method was proposed in which all stages were immersed in water, but water was inserted only between the projection lens and the wafer to accommodate the operation of the high-speed scanner, and water was supplied and drained. A partial fill system with a nozzle was adopted. In principle, lens design with an NA of 1 or more became possible by immersion using water, but the conventional optical system based on the refractive index system became a huge lens, and the lens was deformed by its own weight. There was a problem. A catadioptric optical system has been proposed for a more compact lens design, and a lens design with NA of 1.0 or more has been accelerated. The possibility of a 45 nm node is shown by the combination of a lens with NA 1.2 or higher and strong super-resolution technology (Non-patent Document 2: Proc. SPIE Vol. 5040 p724 (2003)), and further development of a lens with NA 1.35. Has also been done.

  As a lithography technique for the 32 nm node, vacuum ultraviolet light (EUV) lithography with a wavelength of 13.5 nm is cited as a candidate. Problems of EUV lithography include higher laser output, higher resist film sensitivity, higher resolution, lower line edge roughness (LWR), defect-free MoSi laminated mask, lower reflection mirror aberration, etc. There are many problems to overcome.

The resolution of a line pattern that can be reached with the highest NA of water immersion lithography using an NA 1.35 lens is a half pitch of 40 to 38 nm, and cannot reach 32 nm. Therefore, development of a high refractive index material for further increasing NA is being carried out. It is the minimum refractive index among the projection lens, liquid, and resist film that determines the limit of the NA of the lens. In the case of water immersion, the refractive index of water is the lowest compared with the projection lens (refractive index of 1.5 for synthetic quartz) and resist film (refractive index of 1.7 for conventional methacrylate system). The lens NA was fixed. Recently, highly transparent liquids having a refractive index of 1.65 have been developed. In this case, it is necessary to develop a projection lens material having the lowest refractive index and a high refractive index of the projection lens made of synthetic quartz. LUAG (Lu ₃ Al ₅ O ₁₂ ) has a refractive index of 2 or more, and is the most expected material, but has a problem of large birefringence and absorption. Further, even if a projection lens material having a refractive index of 1.8 or more is developed, the NA of the liquid having a refractive index of 1.65 is 1.55, and 35 nm can be resolved, but 32 nm cannot be resolved. In order to resolve 32 nm, a liquid having a refractive index of 1.8 or higher, a resist having a refractive index of 1.8 or higher, and a protective film are required. The most problematic material with a refractive index of 1.8 or higher is a high-refractive-index liquid. At present, there is a trade-off between absorption and refractive index, and no such material has yet been found. In the case of an alkane compound, a bridged cyclic compound is preferable to a linear compound in order to increase the refractive index. However, since the cyclic compound has a high viscosity, there is a problem that it cannot follow high-speed scanning of the exposure apparatus stage. I'm staring. Since particles of hafnium oxide have high transparency at 193 nm and a refractive index exceeds 2, high refractive index liquids in which the particles are dispersed in water or an alkane-based solution have been studied. However, in order to disperse hafnium oxide in water and increase the refractive index to 1.8, it is necessary to mix 30% by mass or more. However, since the viscosity of the mixture becomes very high, high-speed scanning is impossible. . Further, when a liquid having a refractive index of 1.8 is developed, since the minimum refractive index becomes a resist film, the resist film needs to have a high refractive index of 1.8 or more.

  Recently, a double patterning process in which a pattern is formed by the first exposure and development and a pattern is formed just between the first pattern by the second exposure (Non-Patent Document 3: Proc.SPIE Vol.5754 p1508 (2005)). Many processes have been proposed as a double patterning method. For example, the first exposure and development form a photoresist pattern with 1: 3 line and space spacing, the lower hard mask is processed by dry etching, and another hard mask is laid on the first hard mask. In this exposure method, a line pattern is formed by exposure and development of a photoresist film in a space portion of the exposure, and a hard mask is processed by dry etching to form a line-and-space pattern that is half the pitch of the initial pattern. Further, a photoresist pattern having a space and line spacing of 1: 3 is formed by the first exposure and development, the underlying hard mask is processed by dry etching, and a photoresist film is applied thereon. The second space pattern is exposed to the portion where the hard mask remains, and the hard mask is processed by dry etching. In either case, the hard mask is processed by two dry etchings.

  In the above-described method, it is necessary to lay a hard mask twice. In the latter method, only one hard mask is required, but it is necessary to form a trench pattern that is difficult to resolve compared to a line pattern. In the latter method, there is a method using a negative resist material for forming a trench pattern. This can use the same high-contrast light as forming a line with a positive pattern, but the negative resist material has a lower dissolution contrast than the positive resist material. In comparison with the case where the trench pattern having the same dimension is formed with the negative resist material, the resolution is lower when the negative resist material is used than when the negative resist material is formed. The latter method uses a positive resist material to form a wide trench pattern, then heats the substrate to shrink the trench pattern, or coats a water-soluble film on the developed trench pattern. Although it is conceivable to apply the RELACS method in which the trench is shrunk by heating and then crosslinking the resist film surface, there is a disadvantage that the proximity bias is deteriorated and the process is further complicated and the throughput is reduced. .

  Even in the former method and the latter method, etching for substrate processing is required twice, so that there is a problem in that throughput is reduced and pattern deformation and displacement occur due to the two etchings.

  In order to complete the etching once, there is a method in which a negative resist material is used in the first exposure and a positive resist material is used in the second exposure. There is also a method in which a positive resist material is used in the first exposure and a negative resist material dissolved in a higher alcohol having 4 or more carbon atoms that does not dissolve in the second exposure. In these cases, if a negative resist material with low resolution is used, the resolution deteriorates.

  A method in which PEB (post-exposure bake) and development are not performed between the first exposure and the second exposure is the simplest and high throughput method. In this case, the first exposure is performed, the pattern is shifted to a mask on which a shifted pattern is drawn, the second exposure is performed, and PEB, development, and dry etching are performed. However, since the light energy of the first exposure and the light energy of the second exposure are offset, the contrast becomes 0 and the pattern is not formed. In this case, if the acid generation is made non-linear by using a two-photon absorption acid generator or a contrast enhancement film (CEL), the energy offset is relatively small even with exposure shifted by half pitch, and the amount of shift is low but low contrast. It has been reported that a pattern having a half pitch can be formed (Non-patent Document 4: Jpn. J. App. Phys. Vol. 33 (1994) p6874-6877, Part 1, No. 12B, December 1994).

  The most critical problem in double patterning is the alignment accuracy of the first and second patterns. Since the size of the positional deviation is a variation in the line dimensions, for example, if a line of 32 nm is to be formed with an accuracy of 10%, an alignment accuracy within 3.2 nm is simply required. The alignment accuracy of the latest ArF immersion scanner is about 8 to 6 nm for each wafer with the same exposure machine. For each wafer, the resist alignment pattern that has been exposed and developed is aligned by an exposure machine, and this requires a significant improvement. When the first exposure and the second exposure are performed without removing the wafer from the chuck even once, the misalignment due to the chuck remounting can be canceled, so that the alignment accuracy is improved and becomes about 5 to 4 nm. In the case of double patterning, performing a plurality of exposures without removing the wafer from the chuck can be an exposure method that can be realized to the extent that the alignment accuracy is improved. The exposure that forms a nonlinear energy distribution such as the two-photon absorption resist and halves the pitch is performed by shifting the exposure position by ¼ of the pitch without removing the wafer from the chuck. There has not yet been reported a nonlinear resist or CEL that is sensitive to exposure at a wavelength of 193 nm, but if this is completed, double exposure that can be performed with a minimum alignment error becomes realistic.

  As a technique for forming not only double patterning but also a thin space pattern or hole pattern, the above-described method using the negative resist material, the thermal flow method, and the RELACS method can be cited. There is a problem that the resolution is low and there is a problem that bridging occurs in the minute hole pattern due to the use of the cross-linking system, and the thermal flow method and the RELACS method have a problem that variations tend to occur when shrinking the dimensions due to heat. .

  Here, FIG. 1 shows a method of forming a hole pattern by exposure using a positive photoresist material. FIG. 1A shows a method in which a photoresist film 102 is applied and formed on a substrate 101 to be processed on the substrate 100. (B) shows a state in which the photoresist film 102 is exposed through a photomask on which a desired pattern is formed and then developed to form a photoresist pattern 102a. (C) shows a state in which the photoresist pattern 102a is used as a mask. The state which etched the process board | substrate 101 is shown.

  On the other hand, a method of forming a negative pattern by inverting a positive pattern has been well known for a long time. For example, JP-A-2-154266 (Patent Document 1) and JP-A-6-27654 (Patent Document 2). ) Is a method using a naphthoquinone resist material capable of pattern reversal, a method of leaving a portion cured by FIB exposure by subsequent irradiation of the entire surface (Patent Document 3: JP-A-64-7525), and a naphthoquinone diazide photosensitizer. A method in which the indene carboxylic acid generated by exposure is converted into indene by heat treatment in the presence of a base so as to be insoluble in alkali, and positive / negative reversal is caused by overall exposure (Patent Document 4: JP-A-1-191423, Patent Document 5) : JP-A-1-92741). 2A and 2B show this positive / negative reversal method. FIG. 2A shows a state in which a photoresist film 102 is applied and formed on a substrate 101 to be processed on the substrate 100, and FIG. 2B shows a photomask on which a desired pattern is formed. (C) is a state where the photoresist film 102 is flood-exposed, (D) is a state where a pattern reversal film 103 is formed by performing pattern reversal by development, (E) ) Shows a state in which the substrate 101 to be processed is etched using the pattern inversion film 103 as a mask.

  In addition, in the positive / negative reversal method by changing the developer, a method of obtaining a negative pattern by organic solvent development of hydroxystyrene partially protected with t-BOC (tert-butoxycarbonyl group) or development with supercritical carbon dioxide is proposed. Has been.

  As a positive / negative reversal technique using a silicon-containing material, a space portion of a positive resist pattern is covered with a silicon-containing film and etched by oxygen gas etching to remove the positive pattern portion to obtain a silicon-containing film pattern. A method of forming a fine hole pattern by performing positive / negative reversal has been proposed (Patent Document 6: Japanese Patent Laid-Open No. 2001-92154, Patent Document 7: Japanese Patent Laid-Open No. 2005-43420). FIG. 3 shows this. (A) shows a state in which a photoresist film 102 is formed on a substrate 101 to be processed on the substrate 100 via a lower layer film 104, and (B) shows a photomask on which a predetermined pattern is formed. (C) is a state in which the photoresist pattern 102a is crosslinked, (D) is a state in which the crosslinked photoresist pattern 102a is covered, and an SOG film is formed on the lower layer film 104. 105 is formed, (E) is a state in which light-etching with CMP or CF-based gas is performed to expose the crosslinked photoresist pattern 102a, (F) is a state in which the pattern is inverted by etching with oxygen gas and hydrogen gas, ( G) shows a state in which the substrate 101 to be processed is etched using the patterned SOG film 105 as a mask.

It is difficult to make a hole pattern finer than a line pattern. If a hole pattern mask is combined with a positive resist film in order to form a fine hole by a conventional method, an exposure margin becomes extremely narrow. Therefore, a method has been proposed in which a hole having a large size is formed and the hole after development is shrunk by a thermal flow, a RELACS method or the like. However, there is a problem that the control accuracy decreases as the pattern size after development and the size after shrink are large and the shrink amount is large. A positive resist film is used to form a line pattern in the X direction using dipole illumination, the resist pattern is cured, a resist material is again applied thereon, and the line pattern in the Y direction is exposed to light by dipole illumination. A method of forming a hole pattern from a gap of a line pattern (Non-Patent Document 5: Proc. SPIE Vol. 5377 p255 (2004)) has been proposed. A hole pattern can be formed with a wide margin by combining X and Y lines by high-contrast dipole illumination, but it is difficult to etch the line pattern combined vertically with high dimensional accuracy. A method for forming a hole pattern by exposing a negative resist film by combining a Levenson type phase shift mask for X direction lines and a Levenson type phase shift mask for Y direction lines has been proposed (Non-Patent Document 6: IEEE IEDM Tech). Digest 61 (1996)). However, the cross-linked negative resist film has a drawback that the critical dimension is larger than that of the positive resist film because the limit resolution of ultrafine holes is determined by the bridge margin.
A finer pattern can be formed with black spots than with white spots. When the hole size is reduced using a highly transparent halftone or chromeless phase shift mask, the white point is inverted to a black point, and a very small black point with high contrast is formed. An example in which a fine resist hole is formed by combining this with a negative resist film has been reported (Non-patent Document 7: Proc. SPIE Vol. 4000 p266 (2000)). When a half-tone phase shift mask having a high transmittance of 20% is combined with a negative resist film, a mask error factor (MEEF) 0 is obtained (Non-patent Document 8: Proc. SPIE Vol. 5040 p1258). (2003)).

  When the super-resolution technique is used for a dense repetitive pattern, a coarse / dense (proximity) bias with an isolated pattern becomes a problem. The stronger the super-resolution technology is used, the higher the resolution of dense patterns, but the larger the density bias. In particular, an increase in the density bias in the hole pattern is a serious problem. In order to suppress the density bias, generally, a bias is applied to the dimension of the mask pattern. Since the density bias varies depending on the characteristics of the photoresist material, that is, dissolution contrast and acid diffusion, the density bias of the mask changes for each type of photoresist material. The mask with the density bias changed for each type of photoresist material. This increases the burden of mask production. Therefore, only the dense hole pattern is resolved with strong super-resolution illumination, a negative resist film of an alcohol solvent that does not dissolve the first positive resist pattern is applied on the pattern, and unnecessary hole portions are exposed. There has been proposed a method (Pack and unpack; PAU method) in which both a dense pattern and an isolated pattern are produced by blocking by development (Non-patent Document 8: Proc. SPIE Vol. 5753 p171 (2005)). Problems with this method include misalignment between the first exposure and the second exposure, and the author of the literature points out this point. Further, a hole pattern that is not blocked by the second development is developed twice, and a dimensional change due to this is also a problem.

JP-A-2-154266 JP-A-6-27654 JP-A 64-7525 JP-A-1-191423 JP-A-1-92741 JP 2001-92154 A JP-A-2005-43420 JP 2007-171895 A JP 2006-293298 A

Proc. SPIE Vol. 4690 xxix (2002) Proc. SPIE Vol. 5040 p724 (2003) Proc. SPIE Vol. 5754 p1508 (2005) Jpn. J. et al. App. Phys. Vol. 33 (1994) p 6874-6877, Part 1, no. 12B, December 1994 Proc. SPIE Vol. 5377 p255 (2004) IEEE IEDM Tech. Digest 61 (1996) Proc. SPIE Vol. 4000 p266 (2000) Proc. SPIE Vol. 5040 p1258 (2003) Proc. SPIE Vol. 5753 p171 (2005)

  In the case of forming a very fine hole pattern, in double dipole lithography using a negative resist film and a mask of line patterns in the X and Y directions, the resolution is lower than that of a positive resist film. There are a problem that a fine pattern cannot be formed, a problem that throughput is lowered because two exposures are necessary, and a problem that a dimensional difference between a dense pattern and an isolated pattern occurs. On the other hand, if a negative pattern can be inverted after obtaining a positive pattern with high resolution, the problem of resolution due to the use of a negative resist film is solved, and the same exposure as double dipole lithography can be achieved with a single exposure. If an exposure method capable of obtaining a high degree of resolution can be applied, a dense pattern and an isolation can be isolated by applying mask pattern correction (OPC) in consideration of a problem of throughput reduction and proximity bias. The problem of pattern dimensional differences is solved.

  As described above, various methods have been reported for reversing a positive image obtained from a positive resist film capable of obtaining high resolution into a negative pattern. In particular, Patent Document 7 mentioned above also refers to the case where the silicon-based embedding material for positive / negative reversal is an organic solvent-based composition. In the previous method of using a water-soluble silicon resin for the reversal film forming material, if the organic solvent-based reversal film forming material composition is applied to the substrate on which the positive pattern is formed, the positive pattern is applied. Although there was a possibility of collapse with the organic solvent used, if the resin that forms the resist pattern is cross-linked by curing with EB to give resistance to the organic solvent and insolubilization with the solvent is performed, the inversion of the organic solvent system It is disclosed that a film forming material composition can be used, and the selection range of materials can be greatly expanded. However, when this process is performed, the removal of the resist pattern at the final stage for reversal cannot be performed by dissolution because the positive pattern is insolubilized. The method by dry etching must be taken. Therefore, a material that can be selectively dry-etched containing silicon, titanium, or the like must be selected as the inversion film forming material. The silicon resin applied on the resist pattern is etched back by etching with a fluorocarbon gas or the like to expose the resist pattern on the surface, and the image is inverted by dry etching with oxygen gas and hydrogen gas. Since it is necessary to perform two etchings of etching back and etching and gas exchange in order to invert the image, this method reduces the throughput.

  On the other hand, Patent Document 6 discloses that it is advantageous to remove the positive pattern by wet etching, and as a method therefor, after obtaining the positive pattern, the organic silicon is made of organic silicon without any special treatment. A method of applying a solvent solution to form an inversion film made of organic silicon is disclosed. Further, this Patent Document 6 does not mention damage to the positive pattern due to intermixing, and the solvent used for preparing the organic silicon composition has a high polarity (for example, propylene glycol monomethyl ether, lactate ester, etc.). It is described that those having a simple hydroxy group, esters such as propylene glycol monomethyl ether acetate, ketones such as acetone, etc. can be used in the same manner as those having low polarity (for example, toluene, cumene, etc.). In the examples, only examples of toluene and cumene are given. However, as a follow-up to this, for example, a solvent containing a highly polar solvent such as propylene glycol monomethyl ether acetate or ethyl lactate, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, or cyclohexanone. When used as a solvent for the reversal film and applied on a positive pattern without any special treatment, the pattern was dissolved by the coating solvent, and positive / negative reversal satisfying the required accuracy could not be performed. Therefore, in this method, only reversal film materials that exhibit high solubility in low-polar solvents can be used, and novolak, polyhydroxystyrene-based polymers, and alicyclic polymers containing a large amount of hydroxy groups and lactones. It has been found that a reversal film material having a high concentration of polar groups with high substrate adhesion cannot be employed.

When a negative resist material is used in double dipole lithography with a dense line in the X direction and a dense line in the Y direction intersecting therewith, it is possible to obtain an extremely dense hole pattern comparable to the limit resolution of the line. Double dipole lithography requires two exposures by exchanging two masks when full-field exposure is performed. Further, when a logic device pattern in which a dense pattern and an isolated pattern are mixed is formed, first, a dense pattern by two double dipoles is exposed, and then an unnecessary pattern is exposed. A total of three exposures are required, and a significant decrease in throughput is inevitable.
The current exposure apparatus has one mask stage, and exposure is not performed while exchanging three masks for each wafer exposure. Alignment is required every time the mask is exchanged, and not only the exposure time for the three exposures but also the time for the exchange of the mask and the alignment, leading to a significant reduction in throughput.

  The present invention is an improvement of the above-described circumstances, and uses a positive resist film to form a dense dot pattern and an isolated dot pattern in one exposure, and use this to form a hole pattern by positive / negative reversal. It is intended to provide a method.

  According to the present invention, a substrate on which a positive dot pattern is formed is baked at a high temperature, thereby providing resistance to an organic solvent used in the composition for forming a film for reversal as much as necessary and dissolving in an alkaline etching solution. By ensuring the property, it is possible to provide a pattern forming method for forming a hole pattern by positive / negative reversal in which a step of finally obtaining a negative image is performed by wet etching with an alkaline etching solution. In addition, it is possible to provide a technique that enables application of a composition for forming a film for reversal of an organic non-silicone resin such as an aromatic resin or a polycyclic compound resin. In addition, it is possible to provide a technology that makes it possible to use a solvent having a hydroxy group as a solvent used for the preparation of the film forming composition for reversal or a highly polar solvent such as esters and ketones. In addition, it is possible to provide a pattern forming method using positive / negative reversal that can form both hole patterns of dense holes and isolated holes with a wide margin.

  In order to solve the above problems, the present inventor has made various studies and as a result, a phase shift mask in which shifters are arranged in a lattice shape is used to arrange dots wider than the line width at the intersection of the lines. Then, an exposure method was invented in which a dot pattern of a positive resist was formed on a substrate corresponding to this, and both dense and isolated dot patterns were formed by one exposure. By partially crosslinking the chemically amplified positive resist material resin in the positive resist pattern, it is possible to advance the crosslinking to the extent that the required organic solvent resistance is obtained and to dissolve it in an alkaline wet etching solution. If the above operation is incorporated into a negative pattern forming method by positive / negative reversal, not only conventional silicon-based materials but also organic resins such as aromatic resins and polycyclic compound resins can be used as reversal film materials. By enabling the application of a non-silicone resin reversal film-forming material, it is possible to form a hole pattern in which dense and isolated are mixed in a single exposure.

Accordingly, the present invention provides the following pattern forming method.
Claim 1:
A resin having a repeating unit having a structure having an acid labile group that is eliminated by an acid on the substrate to be processed, which becomes soluble in an alkaline developer by the elimination of the acid labile group, exposure of high energy rays Apply a chemically amplified positive resist material containing a photoacid generator that generates acid by heat or a thermal acid generator that generates acid by heating, and an organic solvent, and remove unnecessary solvents by pre-baking. Forming a resist film, a lattice-shaped first shifter having a line width of half a pitch or less on the resist film, and a width on the wafer of 2 to 100 nm on the first shifter than the width of the first shifter. High energy rays are exposed using a phase shift mask in which second shifters having a thick dot pattern are arranged, heated after the exposure, and the acid generated from the acid generator by the exposure is removed from the resin. To act on Sadamoto, after performing the elimination reaction in the acid labile groups of the resin in the exposed area, the exposure step to obtain a positive pattern and then developed with an alkaline developing solution, the positive pattern obtained in about該工and by / or heat to the acid and / or heat, the acid labile group of the resin of the positive pattern of desorbed to improve the alkaline solubility and lose solubility in an alkaline wet etchant to the resin not to form a cross-linked in the range, the step of film loss when allowed to touch 30 seconds in an organic solvent used in the reversal film-forming composition to said positive pattern gives the following solvent resistance 10 nm, the organic forming a reversal film using a reversal film forming composition is a solvent solution, the positive-negative inversion comprising the step of dissolving and removing the positive pattern of the crosslinking is formed by an alkaline wet etchant There was a pattern forming method.
Claim 2:
The pattern forming method according to claim 1, wherein the dots of the second shifter are arranged on the intersection of the first shifter.
Claim 3:
3. The pattern forming method according to claim 1, wherein the shape of the second shifter is a quadrangle, a quadrilateral or more polygon, or a circle.
Claim 4:
The pattern forming method according to claim 1, wherein a dot pattern of the resist after development is formed only on the dot portion of the second shifter.
Claim 5:
5. The pattern forming method according to claim 1, wherein the shifter is a halftone phase shift mask having a transmittance of 3 to 15%.
Claim 6:
The width of the first shifter is 1/3 or less of the pitch, and the second shifter is arranged with dots that are 2-100 nm thicker on the wafer than the line width of the first shifter. 6. The pattern forming method according to claim 1, wherein exposure is performed using a phase shift mask.
Claim 7:
The dissolution rate of the crosslink-forming positive pattern obtained in the step of imparting resistance to the organic solvent used in the reversal film-forming composition to the resist pattern is 2.38 mass% tetramethylammonium hydroxy. When the organic solvent used in the reversal film forming composition is etched with an aqueous solution of TMAH, propylene glycol monomethyl ether acetate, cyclohexanone, ethyl lactate, A single or mixed solvent containing one or more selected from propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, heptanone, and the above The resistance to the solvent used in the diverting film forming composition is 10 nm or less when the cross-linking positive pattern is brought into contact with the solvent used in the reversing film forming composition for 30 seconds. The pattern forming method using positive / negative reversal according to any one of claims 1 to 6, wherein the pattern forming method has solvent resistance.
Claim 8:
The pattern forming method using positive / negative reversal according to any one of claims 1 to 7, wherein the reversal film-forming composition contains a resin containing a monomer unit having an aromatic skeleton or an alicyclic skeleton.
Claim 9:
Between the step of forming a film for reversal using the composition for forming a film for reversal and the step of dissolving and removing the positive pattern for crosslinking formation with an alkaline wet etchant, the film was laminated on the positive pattern for crosslinking formation. The pattern forming method using positive / negative reversal according to claim 1, comprising a step of removing the reversal film.
Claim 10:
10. The pattern forming method using positive / negative reversal according to claim 9, wherein the step of removing the reversal film laminated on the positive pattern is wet etching.
Claim 11:
The reversal film is a material that has a lower dissolution rate and exhibits solubility than the cross-linked positive pattern after the step of imparting resistance to the organic solvent when treated with an alkaline wet etchant, and further comprises the wet etch 11. The step of removing the reversal film laminated on the cross-linking positive type pattern and the step of dissolving and removing the positive type pattern with the alkaline wet etching solution are simultaneously performed using an alkaline wet etching solution. The pattern formation method using the positive / negative reversal described.
Claim 12:
The positive / negative reversal method according to claim 11, wherein the reversal film has a dissolution rate of 0.02 nm / second or more and 2 nm / second or less when etched with a 2.38 mass% tetramethylammonium hydroxide (TMAH) aqueous solution. Pattern formation method.
Claim 13:
13. The positive / negative reversal according to claim 1, wherein the chemically amplified positive resist material contains a component that generates an acid by heating in a step of imparting resistance to an organic solvent to the resist pattern. The pattern forming method used.
Claim 14:
The pattern forming method using positive / negative reversal according to claim 13, wherein the component that generates acid by heating is a thermal acid generator added separately from the photoacid generator.
Claim 15:
The pattern formation method according to claim 14, wherein the thermal acid generator is represented by the following general formula (P1a-2).
Wherein R ^101d , R ^101e , R ^101f and R ^101g are each a hydrogen atom, a linear, branched or cyclic alkyl group having 1 to 12 carbon atoms, an alkenyl group, an oxoalkyl group or an oxoalkenyl group, carbon the number 6 to 20 aryl group, or an aralkyl group or an aryl oxoalkyl group having 7 to 12 carbon atoms, some or all of the hydrogen atoms of these groups and may .R ^101d be substituted by an alkoxy group R ^101e or R ^101d and R ^101e and R ^101f may combine to form a ring together with the nitrogen atom to which they are bonded. When forming a ring, R ^101d and R ^101e or R ^101d R ^101e and R ^{101f each} represent an alkylene group having 3 to 10 carbon atoms or a heteroaromatic ring having a nitrogen atom in the formula in the ring, K ⁻ represents a sulfonic acid in which at least one α-position is fluorinated, Or perfluoroalkyl A bromide acid or perfluoroalkyl methide acid.)
Claim 16:
16. The chemically amplified positive resist material is a positive resist material containing a resin having a repeating unit having a lactone ring as the resin and a repeating unit having an acid labile group that is eliminated by an acid. The pattern formation method using positive / negative inversion of any one of these.
Claim 17 :
The positive resist material is a positive resist material containing a resin having a repeating unit having a 7-oxanorbornane ring and a repeating unit having an acid labile group that is eliminated by an acid. When the acid labile group of the resin in the positive pattern is eliminated by generating and applying heat, the resin crosslinking in the positive pattern and the acid labile group are eliminated simultaneously. Item 17. A pattern forming method using positive / negative reversal according to Item 16 .
Claim 18 :
The pattern forming method using positive / negative reversal according to claim 17 , wherein the repeating unit having a 7-oxanorbornane ring is a repeating unit (a) represented by the following general formula (1).
(In the formula, R ¹ represents a hydrogen atom or a methyl group. R ² is a single bond or a linear, branched or cyclic alkylene group having 1 to 6 carbon atoms, and has an ether group or an ester group. may be, the number of 1 to 6 linear carbon atoms, for branched or cyclic alkylene group, the carbon atom linked to the ester group in the formula is a primary or secondary .R ^3, R ^4, R ⁵ is a hydrogen atom or a linear, branched or cyclic alkyl group having 1 to 6 carbon atoms, and a is in the range of 0 <a <1.0.
Claim 19 :
The pattern forming method according to any one of claims 16 to 18 , wherein the repeating unit having an acid labile group that is eliminated by an acid is the repeating unit (b) represented by the following general formula (2).
(In the formula, R ⁶ represents a hydrogen atom or a methyl group, and R ⁷ represents an acid labile group. B is 0 <b ≦ 0.8.)
Claim 20 :
The pattern forming method according to claim 19 , wherein the acid labile group of R ^{7 is} an acid labile group having an alicyclic structure which is eliminated by an acid.
Claim 21 :
The positive pattern are those containing a dot pattern, the inverted in the resulting pattern pattern formation method using the positive-negative inversion of any one of claims 1 to 20 is intended to include a hole pattern.
Claim 22 :
The positive pattern is intended to include both the isolated dot pattern with dense dot pattern, according to any one of the pattern obtained by the inversion dense hole pattern and an isolated hole pattern is intended to include claims 1 to 21 Pattern formation method using positive / negative reversal.
Claim 23 :
The positive pattern exposes a dense dot pattern, exposes an unnecessary dot pattern portion to form a dense dot pattern and an isolated dot pattern, and forms a dense hole pattern and an isolated hole pattern by the positive / negative reversal. The pattern forming method according to claim 22 .
Claim 24 :
A chemically amplified positive resist material containing a resin having a repeating unit having a structure having an acid labile group that is eliminated by an acid is applied on a substrate to be processed, and unnecessary solvent is removed by heating to form a resist film. Forming a protective film on the resist film, removing unnecessary solvent by heating to form a protective film, water or a refractive index of 1 or more between the resist film and the projection lens The resist film is subjected to immersion exposure of a dense pattern of high energy rays through a transparent liquid, and the unexposed portion of an unnecessary dense pattern is subjected to immersion exposure, and the acid generated by exposure by heating after exposure is acidified. It is obtained in the process of obtaining a positive pattern by acting on an unstable group, causing the acid labile group of the resin in the exposed area to undergo elimination reaction, and then developing with an alkaline developer. Cash register In addition, the acid labile groups of the above resin in the pattern are eliminated, and the resin is crosslinked to the extent that it does not lose its solubility in alkaline wet etching solution. A step of giving a solvent resistance of 10 nm or less when the film is brought into contact with the organic solvent for 30 seconds , a step of forming a reversal film using the reversal film-forming composition as the organic solvent solution, The pattern forming method using positive / negative reversal according to any one of claims 1 to 23 , including a step of dissolving and removing the positive pattern with an alkaline wet etching solution.
Claim 25 :
The pattern forming method according to claim 24 , wherein the composition for forming a protective film contains an amine compound.
Claim 26 :
A carbon film having a carbon content of 75% by mass or more is formed on a substrate to be processed, an intermediate film containing silicon is formed thereon, and the chemically amplified positive resist material is coated thereon and inverted. The pattern forming method according to any one of claims 1 to 25 , wherein the coating film is made of a hydrocarbon-based material.
Claim 27 :
A carbon film having a carbon content of 75% by mass or more is formed on a substrate to be processed, and the chemically amplified positive resist material is coated thereon, and the inversion film is made of a material containing silicon. the pattern forming method according to any one of claims 1 to 25, characterized.
Claim 28 :
A carbon film having a carbon content of 75% by mass or more is formed on a substrate to be processed, an organic antireflection film is formed thereon, and the chemically amplified positive resist material is coated thereon, and a reversal film 28. The pattern forming method according to claim 27 , wherein the pattern forming method is made of a material containing silicon.

Here, in the present invention, FIG. 5 shows the aperture shape of the exposure device of the dipole illumination applied to the Y-direction line pattern mask shown in FIG. 6, and FIG. 7 shows the X-direction line pattern shown in FIG. Aperture shape applied to the mask. The shape of the opening may be a circle shown in FIG. 5, an ellipse shown in FIG. 9, or a fan shown in FIG.
FIG. 11 shows an optical image of an NA 1.3 lens using an ArF excimer laser with a wavelength of 193 nm, a dipole illumination, a 6% halftone phase shift mask, a pitch of 80 nm with s-polarized light, and a Y-direction line having a line size of 40 nm. FIG. 12 shows an optical image of an X-direction line having an NA1.3 lens using an ArF excimer laser with a wavelength of 193 nm, dipole illumination, a 6% halftone phase shift mask, a pitch of 80 nm with s-polarized light, and a line size of 40 nm. The darker one is the light-shielding part and the white one is the strong light area. FIG. 13 is a contrast image in which the optical image of the X direction line is superimposed on the Y direction line. The combination of X and Y lines seems to produce a grid-like image, but this is not the case, and the pattern of the weak light part is circular. When the size of the circle is large, it is easy to connect to the adjacent pattern with a rhombus shape, but it is shown that the degree of circle improves as the size of the circle decreases.
FIG. 14 shows a pattern shape simulation of the resist film based on the optical image image of FIG. Here, in the Z direction, the logarithm of the dissolution rate of the resist film is reciprocal, which reflects the pattern shape of the resist film. It has been shown that a dot pattern of a positive resist film with a pitch of 80 nm can be formed by using double dipole lithography with two exposures of the X and Y lines.
FIG. 15 is a mask layout of a grid pattern of X and Y lines. The black part of the color is the halftone shifter part.
FIG. 16 shows the aperture shape of cross pole illumination corresponding to the lattice mask pattern of the X and Y lines.
FIG. 17 shows the pitch on the wafer (with the layout shown in FIG. 15) with NA1.3 lens using an ArF excimer laser with a wavelength of 193 nm, cross-pole illumination, 6% halftone phase shift mask, and azimuthally polarized illumination. An optical image simulation of a lattice pattern with 90 nm and a line width of 20 nm, and FIG. 18 show the resist shape simulation results. At this time, the sensitivity of the resist is 30 mJ / cm ² .
FIG. 19 shows an optical image simulation of a dot pattern with a pitch of 90 nm and a width of 60 nm, and FIG. 20 shows a resist shape simulation result. The sensitivity of the resist at this time is 45 mJ / cm ² .
FIG. 21 shows an optical image simulation of a dot pattern having a pitch of 90 nm and a width of 65 nm, and FIG. 22 shows a resist shape simulation result. The sensitivity of the resist at this time is 70 mJ / cm ² .
As the dot pattern width increases, the light intensity at the light-shielding portion decreases, the sensitivity of the resist decreases, and the residual film of the resist dot pattern increases.
23, when the pitch 90 nm, the exposure amount in the grid-like pattern having a line width of 20nm of 45 mJ / cm ^2, Figure 24 is a simulation resist configuration when the exposure amount of 70 mJ / cm ^2. When a mask in which a grid pattern with a line width of 20 nm and a dot pattern with 60 nm are arranged is used, when the optimum exposure amount is adjusted to a 60 nm dot, the grid pattern with 20 nm is almost completely dissolved and cannot be formed. It has been shown. The same can be said for the case where a mask having a 20 nm grid pattern and a 65 nm dot pattern is used.
A thin grid pattern is formed on the entire surface, and a dot pattern thicker than this is arranged on the grid intersection of the grid pattern at a place where the dot pattern is to be formed. The resist pattern is not formed on the thin grid, and the resist pattern dots are formed only on the thick dots. The thin grid pattern acts as an auxiliary pattern for increasing the contrast of the dot pattern. As a result, it is possible to form the dots of the dense pattern and the dots of the isolated pattern by one exposure with the same exposure amount.
At a pitch of 90 nm, dots are arranged on the intersections of the grid pattern of the 15 nm line at a portion where a dot resist pattern is to be formed as shown in FIG. The black part of the color is the halftone shifter part. A dot having a wider width (in FIG. 25, a width of 90 nm) is arranged in a place having higher isolation, and a dot having a width of 55 nm is arranged in a dense portion. Large dots are used because the isolated pattern has a lower light intensity than the dense pattern. Since the intensity of light also slightly decreases at the end portion of the dense pattern, 65 nm dots that are slightly wider than the center of the dense portion are assigned.
An optical image of the mask of FIG. 25 is shown in FIG. The place where the dots of the resist pattern are formed is a black portion. Black spots can be seen in places other than where the dots are to be formed. However, since the size of the black spots is small, the dots are actually hardly transferred. It is possible to prevent unnecessary dot transfer by optimizing the grid line width of unnecessary dot portions. FIG. 27 shows the result of simulating the resist shape based on the optical image of FIG. It is shown that both dense dots and isolated dots are formed with an exposure amount of 70 mJ / cm ² .

When dots are formed by a conventional method, a mask provided with a dot pattern has been used. FIG. 28 shows a mask pattern in which a dot pattern is arranged. The black part of the color is the halftone shifter part. The isolated dots are larger in pattern than the dense dots, and this reduces the density bias. The size of the dense dot is 55 nm for one piece, whereas it is 90 nm for an isolated dot.
An optical image of the mask of FIG. 28 is shown in FIG. There are no black dots in the light-shielding portion of FIG. 29, and the light-shielding property is low compared to the image of FIG. The result of calculating the resist shape based on the optical image of FIG. 29 is shown in FIG. The remaining film of the dot pattern is lower than that in FIG. 27, which is because there is no strong light-shielding portion in FIG. When the remaining film of the dot pattern is lowered, the reversal dissolution does not proceed when the reversal film is applied thereon and the reversal process is performed.

In the PAU method described above, a positive resist film is used to form dense holes by the first exposure, and a negative resist film dissolved in alcohol or water that does not dissolve the positive resist film is coated on the positive hole. Erase the required hole pattern. This also forms a dense pattern with uniform dimensions first, so no proximity bias is generated. In the PAU method, since the hole pattern is exposed in the first exposure, the resolution is not improved as compared with the normal exposure method, and only the proximity bias is eliminated.
However, in the pattern forming method of the present invention, a dense and isolated dot pattern is formed by a single exposure using a high-contrast grid line pattern mask, which is a solution compared to the conventional method of forming holes. The image quality is also greatly improved, and it is advantageous in terms of throughput as compared with the double exposure of the PAU method.

  Compared to the method of forming fine holes by combining double dipole lithography and a negative resist film, the pattern forming method of the present invention uses the positive resist film to achieve the same resolution as a double dipole in a single exposure. It is possible to form a hole pattern by forming a dot pattern having the characteristics and inverting the positive / negative. By using a high-resolution positive resist film as compared with a negative resist film, process margins such as resolution, focus margin, and exposure margin are expanded. Since the positive / negative reversal is performed by wet etching using a developer, the throughput is higher than that of conventional dry development, and an etching apparatus for dry development is not required. Double dipole lithography required two masks, but with the pattern formation method of the present invention, a resolution equal to that of double dipole lithography can be obtained with only one phase shift mask having a lattice pattern with different line widths. Furthermore, both dense patterns and isolated patterns can be formed by one exposure.

It is sectional drawing explaining the method of forming a hole pattern by exposure using a positive photoresist material as a conventional method, (A) is formation of a photoresist film, (B) is exposure and development of a photoresist film. , (C) shows a state where the substrate to be processed is etched. Sectional drawing explaining the image reversal method using the positive i line | wire and g line | wire resist material of a quinonediazide- novolak resin as a conventional method, (A) is formation of a photoresist film, (B) is a photoresist film | membrane. Exposure and heating, (C) shows flood exposure, (D) shows pattern reversal by development, and (E) shows a state where the substrate to be processed is etched. Sectional drawing explaining the image reversal method by the hardening of the resist film after image development, and embedding of an SOG film as a conventional method, (A) is formation of a photoresist film, (B) is exposure and development of a photoresist film (C) is cross-linking of the photoresist film, (D) is SOG film coating, (E) is light etching with CMP or CF gas, (F) is pattern inversion with oxygen gas or hydrogen gas etching, and (G) is covered. In this state, the processed substrate is etched. It is sectional drawing explaining the pattern formation method of this invention, (A) is the state which formed the to-be-processed substrate and the resist film on the board | substrate, (B) is the state which exposed and developed the resist film, (C) Is a state where the resist pattern is deprotected and cross-linked with acid and heat, (D) is a state where a pattern reversal film is applied, (E) is a state where a pattern reversal film is developed and positive / negative is reversed, F) shows a state in which the substrate to be processed is etched using a positive / negative pattern. The shape of the aperture part of the exposure machine used for Y dipole illumination exposure is shown. The Y direction line shape of the mask used for Y dipole illumination is shown. The shape of the aperture part of the exposure machine used for X dipole illumination exposure is shown. The X direction line shape of the mask used for X dipole illumination is shown. The elliptical aperture shape of the exposure machine used for Y dipole illumination exposure is shown. The fan-shaped aperture shape of the exposure machine used for Y dipole illumination exposure is shown. The light intensity in the case of using a Y direction line, dipole illumination, s-polarized illumination, and a 6% halftone phase shift mask with an NA1.3 lens is shown. The darker the color, the weaker the light intensity. The light intensity in the case of using an X direction line with NA 1.3 lens, dipole illumination, s-polarized illumination, and a 6% halftone phase shift mask is shown. The darker the color, the weaker the light intensity. FIG. 13 shows the light intensity of double dipole exposure in which the Y direction line of FIG. 11 and the X line of FIG. The darker the color, the weaker the light intensity. The resist shape simulation in the case of performing double dipole illumination exposure with an NA 1.3 lens is shown. The Z axis is obtained by reciprocal of the logarithm of the resist dissolution rate, and represents the resist shape of the dot pattern. The exposure amount at this time is 20 mJ / cm ² . This is a lattice mask pattern of X and Y lines. The black part is the halftone shifter. The shape of the aperture part of the cross pole illumination of the exposure apparatus adapted to the lattice mask of X and Y lines is shown. It is a simulation result of the optical image of the grid | lattice-like pattern of pitch 90nm and 20nm line in NA1.3 lens, cross pole illumination, 6% halftone phase shift mask, and azimuthally polarized illumination. It is a resist shape simulation result when the exposure amount in the optical image of FIG. 17 is 30 mJ / cm ² . It is a simulation result of an optical image of a square dot pattern having a pitch of 90 nm and a side of 60 nm with NA 1.3 lens, cross pole illumination, 6% halftone phase shift mask, and azimuthally polarized illumination. It is a resist shape simulation result when the exposure amount in the optical image of FIG. 19 is 45 mJ / cm ² . It is a simulation result of an optical image of a square dot pattern having a pitch of 90 nm and a side of 65 nm with NA 1.3 lens, cross pole illumination, 6% halftone phase shift mask, and azimuthally polarized illumination. It is a resist shape simulation result when the exposure amount in the optical image of FIG. 21 is 70 mJ / cm ² . It is a resist shape simulation result when the exposure amount in the optical image of FIG. 17 is 45 mJ / cm ² . It is a resist shape simulation result when the exposure amount in the optical image of FIG. 17 is 70 mJ / cm ² . This is a mask pattern in which dot patterns are arranged in a grid pattern of X and Y lines. The black part is a 6% halftone shifter. It is an optical image with NA1.3 lens, cross pole illumination, the halftone phase shift mask of FIG. 25, and azimuthally polarized illumination. It is a resist shape simulation result in the optical image of FIG. This is a dot mask pattern in which the dot size is changed. The black part is a 6% halftone shifter. It is an optical image with NA1.3 lens, cross pole illumination, 6% halftone phase shift mask of FIG. 28, and azimuthally polarized illumination. It is a resist shape simulation result in the optical image of FIG. The part of the arrow is a mask pattern in which the positions of the grid shifter and the dot are shifted. FIG. 26 is a resist shape simulation result of exposure using a NA1.3 lens, cross pole illumination, and azimuthally polarized illumination using a mask having the same line width of the mask pattern of FIG. 25 and a pitch reduced to 80 nm. It is the resist shape simulation result exposed using the NA1.3 lens, cross pole illumination, and azimuthally polarized illumination using the mask which reduced the pitch to 80 nm with the same line width of the mask pattern of FIG. The mask patterns used in Examples 1 and 2 are the length measurement positions of the corresponding resist patterns. It is the length measurement position of the mask pattern used for the comparative example 1, and the resist pattern corresponding to this.

Dots are formed at the intersections of the lattices using a mask provided with a lattice-like halftone shifter pattern. A grid pattern is also formed in a place where dots are not formed, the line width of the first shifter grid where dots are not formed is narrowed, and a dot that becomes the second shifter at the intersection of the grids of the first shifter Place. Since the first shifter serves as an auxiliary pattern for the second dot shifter, it does not need to be transferred as a resist pattern after development. Therefore, it is necessary to make the second pattern larger than the first pattern. The difference between the widths of the first shifter and the second shifter needs to be 2 to 100 nm, preferably 5 to 90 nm. The width of the first shifter is preferably 5 to 40 nm thinner than half the pitch. In the case of a lattice having a pitch of 90 nm, the width of the first shifter is about 10 to 20 nm, and the width of the dots of the second shifter is 25 to 100 nm. The length of one side of the dots of the second shifter is preferably in the range of 50 to 60 nm, particularly about 55 nm for a dense pattern, and preferably in the range of 80 to 100 nm, particularly about 90 nm for an isolated pattern. The second dot pattern is most preferably a square, but may be a rectangle, a rhombus, a trapezoid, a parallelogram, a pentagon, a hexagon, an octagon, or a circle.
The transmission of the halftone of the shifter is 3 to 15%, preferably 4 to 10%. If all the pitches of the first shifters are the same, the effect of improving the contrast is the highest. However, since the second shifters need to be arranged on the first shifters, the positions of the dots of the positive resist are Limited to multiples of shifter half pitch. In order to shift the dot position, the first and second shifters can be shifted as indicated by the arrows in FIG.
As the illumination of the exposure machine, in the case of an X and Y lattice mask, it is most preferable to combine the cross pole illumination of the aperture shown in FIG. 16 with the X and Y polarization illumination. Azimuthally polarized illumination may be used instead of X and Y polarized illumination. Azimuthally polarized illumination is ring-shaped annular polarized illumination, but the combination with cross pole illumination that cuts out only the outermost cross in the X and Y directions has the same practical effect as X and Y polarized illumination. It is.
Instead of cross pole illumination, the X and Y dipoles of the aperture shown in FIGS. 7 and 5 can be exposed twice. The substantial effect is almost the same as that of the cross pole, but the two dipole exposures are disadvantageous in terms of throughput.
When an oblique 45 degree lattice mask is used, an oblique 45 degree cross pole and azimuthally polarized illumination are combined. Instead of the cross pole, annular illumination and azimuthally polarized illumination may be combined, hexapole and azimuthally polarized illumination may be combined, or octopole and azimuthally polarized illumination may be combined. Annular illumination, a cross pole, a hexapole or an octopole having a small circle or annulus in the central portion may be used. Although it is not necessary to use polarized illumination, a pattern with a finer pitch can be formed by using polarized illumination. The finest pitch can be formed by a combination of X and Y lattice mask, cross pole (the outermost part is cut out at an angle of 35 degrees or less, preferably 25 degrees or less), and X and Y polarized illumination. is there.
The fundamental resolution limit of the line pattern is a value obtained by dividing the wavelength by the NA of the lens and 4. When NA is 1.30 with ArF exposure at a wavelength of 193 nm, the limiting resolution is 37.1 nm. Actually, the change rate of the polarized illumination is not 100%, and it is difficult to make the cut-out angle of the dipole illumination smaller than 20%. Therefore, it is impossible to form an ideal optical image. Since a fine pattern has a great influence on the resolution performance of the resist, the actual limit resolution is 38 nm in a pinpoint manner, and the resolution limit with a certain margin is 39 nm.

  However, if the pattern forming method of the present invention is used, a dot with a half pitch of 40 nm, which is the same as a line, can be resolved, although a slight film reduction is recognized in the simulation in spite of the two-dimensional pattern as shown in FIG. In addition, it is shown that both dense patterns and isolated patterns can be formed by one exposure. In FIG. 32, calculation is performed using a mask in which the line width of the mask of FIG. 25 is the same and only the pitch is reduced from 90 nm to 80 nm. FIG. 33 shows the calculation result of the resist shape when the dot size of the mask of FIG. 28 is the same and the pitch is 80 nm. The connection between the decrease in the film thickness of the isolated pattern and the dense pattern is remarkable, indicating that no pattern is formed.

  As described above, several attempts have been made to use positive-negative reversal to form patterns that are optically unfavorable if positive resist materials are used as they are. I came. The challenge overcome in this development process is how to form a new film without collapsing the obtained pattern when forming a reversal film on the positive pattern once formed. One of them is good. In order to solve this problem, an aqueous composition in which a positive pattern is not dissolved is used as a reversal film forming composition at first, but the reversal film material is extremely water-soluble. For this reason, Patent Document 7 proposes to form a reversal film after the positive pattern is cross-linked by EB cure and insolubilized in a solvent or a developer. Another problem is how to selectively remove the positive pattern with respect to the inversion film. However, as disclosed in Patent Document 7, this can be achieved by dry etching with oxygen on the inversion film. Selective removal has been carried out by using resistant SOG and organic silicone materials.

  On the other hand, the resist film as shown in Patent Document 7 is cross-linked and insolubilized by high energy light irradiation in the early stage of chemical amplification resist material development when the chemical amplification resist film is irradiated with too high irradiation energy. It was known as a phenomenon. In other words, when the polyhydroxystyrene unit, which is a component of a chemically amplified resist polymer, is exposed to intense light, the hydrogen radicals of methine bonded with phenyl groups are eliminated, and the resulting radicals form crosslinks between the resins. This is a phenomenon in which the resin becomes insoluble. It is considered that the generation of radicals that cause this cross-linking formation is not limited to the styrene skeleton but also occurs in the polyacrylic acid skeleton, and the same cross-linking is considered to occur in methylene bonded to a hetero atom. However, the present inventor observed that the insolubilization of the resist film due to this cross-linking formation is not insolubilized all at once when light irradiation is performed stepwise, but it is insolubilized through a point where the dissolution rate is slightly lowered, I thought about using it. In other words, the decrease in dissolution rate initially observed is considered to be the effect of forming intramolecular or intermolecular cross-links within a limited range, and when cross-linked within a limited range, dissolution in an alkaline developer Tolerance to organic solvents such as coating solvents can be obtained without losing speed completely. Accordingly, when the production of a pattern having resistance to an organic solvent generally used as a solvent for a film-forming composition was examined without completely losing the dissolution rate in such an alkaline developer, Have found that a simple pattern is feasible.

  If the method of imparting resistance to an organic solvent without completely losing the solubility in an alkaline developer in the positive pattern as described above is incorporated into the pattern forming method using positive / negative reversal, the following positive type pattern is obtained. A pattern forming method for inverting the pattern to a negative pattern is possible. That is, according to a normal method for obtaining a positive pattern, first, a chemically amplified positive resist material is applied and then pre-baked to obtain a resist film. Next, after performing pattern exposure, heating is performed after the exposure to remove the acid labile group of the resin in the exposed portion, thereby rendering the exposed portion soluble in alkali development. Further, development with an alkaline developer is performed to obtain a positive pattern. Next, the positive pattern obtained here is subjected to a step of imparting resistance to the organic solvent used in the reversal film-forming composition without completely losing the dissolution rate in the alkaline developer described above. Next, the reversal film-forming composition, which is the organic solvent solution, is applied to a substrate on which a positive pattern having resistance to the organic solvent used in the reversal film-forming composition is formed. Form. At this time, the inversion film is applied so as to completely fill the gaps in the positive pattern, but the film may be formed in a form laminated to some extent on the positive pattern. In such a case, as described in Patent Literature 6 and Patent Literature 7, after the step of forming the inversion film, the step of removing the inversion film stacked on the pattern is performed, and then the positive pattern Is removed with an alkaline wet etching solution, only the reversal film where there is no positive pattern remains, and a reversal film pattern in which positive / negative reversal is performed is obtained. The alkaline wet etching solution is for dissolving the positive pattern, and the concentration may be adjusted as necessary, but a developer for obtaining the positive pattern can be used.

  In the pattern forming method using positive / negative reversal according to the process of the present invention, it is not necessary to use conventional dry etching with oxygen to remove the positive pattern, and the operation can be greatly simplified. Furthermore, according to this pattern formation method, the reversal film is an ordinary organic film such as an antireflection film made of an aromatic organic polymer material or an organic underlayer film used in a multilayer resist method, particularly well known to those skilled in the art. A resin containing a large amount of a unit having an aromatic skeleton, such as a novolac resin (for example, Patent Document 8: JP-A-2007-171895), a polystyrene resin, an anthracene ring or a naphthalene ring An organic film containing a vinyl ether or acrylic resin, or a multi-branched (so-called aliphatic polycyclic skeleton) resin as used in an ArF resist material (for example, Patent Document 9: Japanese Patent Application Laid-Open No. 2006-293298) ) Can be used as the inversion film. Of course, if these reversal films have a difference in dissolution rate from the positive pattern to an etching selectivity with respect to an alkaline wet etchant, they form a bridge during film formation like an antireflection film. Even those that are insolubilized in an organic solvent may be those that are not so insolubilized. If these organic material films are used, the reversal film pattern obtained by reversal is directly used as an etching mask for processing metal silicon or silicon oxide substrates in the same way as conventional organic resist patterns. it can. As is well known, if an organic inversion film as described above is used, silicon nitride, silicon nitride oxide, titanium oxide, titanium nitride, germanium oxide can be used in addition to silicon metal and silicon oxide. It is also possible to process a film or a substrate with an object, hafnium oxide.

  In addition, if a reversal film having an alkali solubility as described below is used, the conventional dry etching is used in the reversal film removal step laminated on the positive resist pattern. It can be removed with an alkaline wet etching solution without using the method according to 1 and the peeling method with an organic solvent. Therefore, when this method is adopted, the reversal film and the resist pattern laminated on the resist pattern can be simultaneously removed by a single operation, so that the process can be greatly shortened as a whole. The

  As described above, imparting resistance to the organic solvent used in the reversal film forming composition to the positive pattern without completely losing the solubility in the alkaline wet etching solution is the application of the reversal film. This is to prevent the positive pattern from being deformed or collapsed by dissolution in the film, but as described above, this can be performed by irradiation with a high energy ray having an appropriate energy amount. However, the present inventor found that the cross-linking formation by light or irradiation is difficult to control due to the tolerance of irradiation dose and the problem of uniformity of irradiation. It is possible to achieve the above-mentioned limited cross-linking that gives organic solvent resistance, especially by heating in the presence of an acid, using a resist material having a unit capable of forming a cross-linkage under strong reaction conditions including a lactone skeleton. It was found that when the positive pattern was used, control as intended was relatively easy.

  The process of imparting resistance to the organic solvent used in the composition for forming a film for reversal without losing the solubility in the alkaline wet etching solution due to the heat described above is the amount of acid to be generated by the resist material used or heating. Although the optimum temperature value to be used is different, the pattern forming method of the present invention can be easily implemented by setting the conditions based on the following guidelines. That is, an acid is generated in the resist film by applying heat after irradiation with high energy rays such as light and EB (electron beam) in an appropriate range for the resist film to be used, or by heating alone, and using it. Thus, the acid labile group of the resin is eliminated to provide solubility in an alkaline solution. At this time, partial crosslinking is simultaneously formed by light or heat, and resistance to the organic solvent used in the composition for forming a film for reversal is given. The standard of solubility to be given above is that when etching is performed with a 2.38 mass% tetramethylammonium hydroxide (TMAH) aqueous solution usually used for alkali development of a resist film, the etching rate exceeds 2 nm / second. It is preferable to do. In addition, the resistance to the organic solvent used in the reversal film-forming composition is such that the resist pattern after the resistance (crosslinking) treatment is applied to the organic solvent used in the reversal film-forming composition for 30 seconds. Preferably, if the film loss when touched for 60 seconds is 10 nm or less and gives a certain degree of solvent resistance, the pattern obtained from the positive resist film when the reversal film as described above is applied is fatal. Occurrence of a problem that a pattern reversed to a negative shape having a desired shape cannot be obtained. In determining the processing conditions, in the above-described series of steps, only the pattern exposure for performing the positive pattern formation is omitted, and the resist film is applied, pre-baked, and the bulk film subjected to post-exposure heating is subjected to the above process. Without using the solubility in the alkaline wet etching solution, if using a condition that is a candidate process for imparting resistance to the organic solvent used in the reversal film-forming composition, the above two dissolution rates can be achieved. It is easily obtained.

  In addition, the organic solvent used in the composition for forming a film for reversal that the present invention can be used particularly effectively dissolves the organic polymer material having the adhesive group described above, and has excellent coating properties. Examples of the above-mentioned solvents having hydroxy groups, esters, ketones and the like include propylene glycol monomethyl ether acetate, cyclohexanone, ethyl lactate, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl. A single solvent or a mixed solvent containing one or more selected from ether, propylene glycol monobutyl ether, and heptanone. Furthermore, you may add C3-C10 alcohol, toluene, xylene, anisole, etc. to these solvents. Therefore, as a standard for giving the positive pattern resistance to the organic solvent used in the above reversal film forming composition, it is 30 seconds with respect to a single solvent or a mixed solvent selected from among them for 30 seconds, More preferably, any film having a film thickness of 10 nm or less when touched for 60 seconds and having a certain degree of solvent resistance can be universally used.

  The above heat treatment for the positive type pattern is used when obtaining a positive type pattern when the partial crosslinking is performed by irradiation with high energy rays, because the reaction performed by heating is only the decomposition of the acid labile group. It is sufficient to perform the heating at a temperature slightly lower than the post-exposure heating temperature. However, when high energy rays are not used, or high energy rays are used for the main purpose of generating an acid, that is, the amount of energy equivalent to that of pattern exposure in the previous process is used, and crosslinking is mainly due to heat. When forming by reaction, it is preferable to set a temperature higher than the pre-bake temperature and post-exposure heating temperature used when forming the resist film. In the case of a material in which this temperature is set lower than the heating in the previous process, there is a risk that the resolution itself of the positive resist film is lowered.

This positive / negative reversing method can be advantageously used in the following cases. That is, the positive pattern can form a finer pattern depending on the overexposure amount. Thus, for example, although it is extremely difficult to form an isolated space (trench pattern) below the exposure limit, a pattern thinner than the normal exposure limit is formed using overexposure, and this is formed by the pattern forming method of the present invention. A very thin trench pattern can be formed by inversion.
In addition, a fine hole pattern is more technically difficult than a trench pattern, but a fine dot pattern is formed by overexposure, and this is reversed by the pattern formation method of the present invention. Holes can be formed.

  As a typical example of the present invention, a material having a slight solubility in an inversion film in an alkaline wet etching solution (substantially synonymous with an alkaline developer used for developing a resist pattern, hereinafter also referred to as an alkaline developer). The present invention will be described in more detail using the case of using.

The pattern forming method of the most preferred embodiment of the present invention has a repeating unit having an acid labile group that is eliminated by an acid, preferably an alicyclic structure, and the acid labile group is eliminated and further crosslinked. A positive resist material containing a polymer compound (base resin) having a dissolution rate in an alkaline developer of the resulting cross-linked product exceeding 2 nm / second is applied onto a substrate to form a resist film, and after heating, high energy rays Then, a desired portion of the resist film is exposed, and after the heat treatment, the resist film is developed using the alkaline developer to form a resist pattern. Thereafter, an acid is generated in the resist pattern and heat is applied to remove the acid labile group of the polymer compound in the resist pattern and to crosslink the polymer compound. Then, an inversion film having a dissolution rate in the range of 0.02 nm / second or more and 2 nm / second or less is formed in the alkaline developer on the substrate, and the surface of the film is covered with the alkaline developer. The resist pattern is dissolved and disappeared while being dissolved, and a pattern in which the resist pattern is inverted is formed on the inversion film.
In this case, a dot pattern can be formed as a resist pattern, and this can be reversed to form a hole pattern.

  The cross-linking is preferably performed by an electrophilic partial structure such as an ester group or a cyclic ether in the resin. By the acid and heating, the cross-linking reaction proceeds by reactions such as transesterification, lactone ring opening and esterification and etherification, and cyclic ether ring opening and etherification and esterification.

  The polymer compound used for the base resin of the positive resist material used in the pattern forming method according to the present invention is a repeating unit having a lactone ring, particularly a repeating unit having a 7-oxanorbornane ring, preferably What has the repeating unit (a) shown by Formula (1) can be used advantageously. Since this has both an ester group and a cyclic ether in a single repeating unit, the reactivity of the crosslinking reaction is high. Further, this unit is used as an adhesive unit, and the pattern forming method of the present invention can be preferably applied without adding an additional component to the base resin.

(In the formula, R ¹ represents a hydrogen atom or a methyl group. R ² is a single bond or a linear, branched or cyclic alkylene group having 1 to 6 carbon atoms, and has an ether group or an ester group. may be, the number of 1 to 6 linear carbon atoms, for branched or cyclic alkylene group, the carbon atom linked to the ester group in the formula is a primary or secondary .R ^3, R ^4, R ⁵ is a hydrogen atom or a linear, branched or cyclic alkyl group having 1 to 6 carbon atoms, and a is in the range of 0 <a <1.0.

  Here, as a C1-C6 alkylene group, a methylene group, ethylene group, n-propylene group, isopropylene group, n-butylene group, isobutylene group, sec-butylene group, n-pentylene group, isopentylene group, Examples include a cyclopentylene group, an n-hexylene group, and a cyclohexylene group.

  Examples of the alkyl group having 1 to 6 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, n-pentyl group, isopentyl group, and cyclopentyl group. , N-hexyl group and cyclohexyl group.

The monomer for obtaining the repeating unit (a) represented by the general formula (1) is represented by the following general formula Ma, specifically exemplified below. Here, R ^{1 to} R ⁵ are the same as described above.

In the process of the present invention, after the first pattern is formed by exposure and development, an acid labile group is deprotected and cross-linked by acid and heating, and a film (reversal film) having moderate alkali solubility thereon is formed. Apply and develop with alkali.
In the first pattern, a repeating unit having an acid labile group is dissolved in an alkali by deprotection of the acid labile group, and a solvent (solvent of a material for forming a film for inversion is formed by crosslinking of a 7-oxanorbornane ring. ) Becomes an insoluble film. Therefore, even if a pattern reversal film solution obtained by dissolving a reversal film material in an organic solvent is applied on the first pattern, the first pattern does not mix with the pattern reversal film material.
Next, when the surface of the reversal film is dissolved up to the first pattern portion by the treatment with the alkaline developer, the dissolution of the first pattern starts and image reversal occurs.
When a polymer compound having a repeating unit having oxirane or oxetane is used as the base polymer for resist, the oxirane ring or oxetane ring has a very high rate of cleavage reaction with acid, and therefore, a post-exposure of about 90-130 ° C. Since crosslinking proceeds at the temperature of a resist process such as Jure baking (PEB), it becomes insoluble in alkali and does not function as a positive resist material in the present invention. On the other hand, the 1,4-epoxy bond of the 7-oxanorbornane ring is less reactive in the cleavage reaction with acid than the oxirane ring or oxetane ring, so that the crosslinking does not proceed in the heating temperature region with PEB. The repeating unit having a 7-oxanorbornane ring is stable to an acid in the process until development, and exhibits a function for improving adhesion and alkali solubility as a hydrophilic group. However, the acid generated by flood exposure or heating of the pattern after development and heating at 170 ° C. or more cause the 1,4-epoxy bond of the 7-oxanorbornane ring to open and the crosslinking reaction proceeds, making it insoluble in the solvent. At the same time, deprotection of the acid labile group of the repeating unit having the acid labile group occurs by acid and heat, and alkali solubility increases. In order to generate an acid, a thermal acid generator may be added to the resist material, or the entire pattern after development may be irradiated with ultraviolet rays having a wavelength of 400 nm or less.

  The base resin used for the positive resist material in the pattern forming method of the present invention includes a crosslinkable repeating unit (a) represented by the general formula (1) and an acid labile group represented by the following general formula (2). It is preferable to use a polymer compound containing the repeating unit (b) having

(In the formula, R ⁶ represents a hydrogen atom or a methyl group, and R ⁷ represents an acid labile group. B is in the range of 0 <b ≦ 0.8.)

Here, the monomer Mb for obtaining the repeating unit (b) represented by the general formula (2) is represented by the following formula.
(In the formula, R ⁶ and R ⁷ are as described above.)

In the general formula (2), various acid labile groups represented by R ⁷ are selected. In particular, groups represented by the following formulas (AL-10) and (AL-11), and the following formula (AL-12): The tertiary alkyl group shown, the C4-C20 oxoalkyl group, etc. are mentioned.

In the formulas (AL-10) and (AL-11), R ⁵¹ and R ⁵⁴ are monovalent hydrocarbon groups such as a linear, branched or cyclic alkyl group having 1 to 40 carbon atoms, particularly 1 to 20 carbon atoms. Yes, it may contain heteroatoms such as oxygen, sulfur, nitrogen and fluorine. R ⁵² and R ⁵³ are each a hydrogen atom or a monovalent hydrocarbon group such as a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, and includes heteroatoms such as oxygen, sulfur, nitrogen and fluorine. Alternatively, a5 is an integer of 0 to 10, particularly 1 to 5. R ⁵² and R ⁵³ , R ⁵² and R ⁵⁴ , or R ⁵³ and R ⁵⁴ are bonded to each other to form a ring having 3 to 20 carbon atoms, particularly 4 to 16 carbon atoms, together with the carbon atom or carbon atom and oxygen atom to which they are bonded, An alicyclic ring may be formed.
R ⁵⁵ , R ⁵⁶ , and R ⁵⁷ are each a monovalent hydrocarbon group such as a linear, branched, or cyclic alkyl group having 1 to 20 carbon atoms, and include heteroatoms such as oxygen, sulfur, nitrogen, and fluorine. But you can. Alternatively, R ⁵⁵ and R ⁵⁶ , R ⁵⁵ and R ⁵⁷ , or R ⁵⁶ and R ⁵⁷ are combined to form a ring having 3 to 20 carbon atoms, particularly 4 to 16 carbon atoms, particularly an alicyclic ring, together with the carbon atom to which they are bonded. May be.

  Specific examples of the compound represented by the formula (AL-10) include tert-butoxycarbonyl group, tert-butoxycarbonylmethyl group, tert-amyloxycarbonyl group, tert-amyloxycarbonylmethyl group, 1-ethoxyethoxycarbonyl. Examples include a methyl group, 2-tetrahydropyranyloxycarbonylmethyl group, 2-tetrahydrofuranyloxycarbonylmethyl group and the like, and substituents represented by the following general formulas (AL-10) -1 to (AL-10) -10. .

In the formulas (AL-10) -1 to (AL-10) -10, R ⁵⁸ is the same or different linear, branched or cyclic alkyl group having 1 to 8 carbon atoms, aryl having 6 to 20 carbon atoms. Group or a C7-20 aralkyl group is shown. R ⁵⁹ represents a hydrogen atom or a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms. R ⁶⁰ represents an aryl group having 6 to 20 carbon atoms or an aralkyl group having 7 to 20 carbon atoms. a5 is as described above.

  Examples of the acetal compound represented by the formula (AL-11) are (AL-11) -1 to (AL-11) -34.

  Examples of the acid labile group include groups represented by the following general formula (AL-11a) or (AL-11b), and the base resin may be intermolecularly or intramolecularly crosslinked by the acid labile group. Good.

In the above formula, R ⁶¹ and R ⁶² represent a hydrogen atom or a linear, branched or cyclic alkyl group having 1 to 8 carbon atoms. Alternatively, R ⁶¹ and R ⁶² may be bonded to form a ring together with the carbon atom to which they are bonded, and when forming a ring, R ⁶¹ and R ⁶² are linear or branched having 1 to 8 carbon atoms. -Like alkylene group. R ⁶³ is a linear, branched or cyclic alkylene group having 1 to 10 carbon atoms, b5 and d5 are 0 or an integer of 1 to 10, preferably 0 or an integer of 1 to 5, and c5 is an integer of 1 to 7. It is. A represents a (c5 + 1) -valent aliphatic or alicyclic saturated hydrocarbon group having 1 to 50 carbon atoms, an aromatic hydrocarbon group or a heterocyclic group, and these groups are heteroatoms such as oxygen, sulfur and nitrogen. Or a part of hydrogen atoms bonded to the carbon atom may be substituted with a hydroxyl group, a carboxyl group, a carbonyl group or a fluorine atom. B represents —CO—O—, —NHCO—O— or —NHCONH—.

  In this case, A is preferably a divalent to tetravalent C1-C20 linear, branched or cyclic alkylene group, alkanetriyl group, alkanetetrayl group, or C6-C30 arylene group. These groups may have intervening heteroatoms such as oxygen, sulfur, nitrogen, etc., and some of the hydrogen atoms bonded to the carbon atoms are substituted by hydroxyl groups, carboxyl groups, acyl groups or halogen atoms. Also good. C5 is preferably an integer of 1 to 3.

  Specific examples of the crosslinked acetal groups represented by the general formulas (AL-11a) and (AL-11b) include those represented by the following formulas (AL-11) -35 to (AL-11) -42.

  Next, examples of the tertiary alkyl group represented by the formula (AL-12) include tert-butyl group, triethylcarbyl group, 1-ethylnorbornyl group, 1-methylcyclohexyl group, 1-ethylcyclopentyl group, tert Examples thereof include an amyl group and the like, or groups represented by the following general formulas (AL-12) -1 to (AL-12) -16.

In the above formula, R ⁶⁴ represents the same or different linear, branched or cyclic alkyl group having 1 to 8 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms. R ⁶⁵ and R ^{67 each} represent a hydrogen atom or a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms. R ⁶⁶ represents an aryl group having 6 to 20 carbon atoms or an aralkyl group having 7 to 20 carbon atoms.

Furthermore, examples of the acid labile group include groups represented by the following formulas (AL-12) -17 and (AL-12) -18, and the acid containing R ⁶⁸ which is a divalent or higher valent alkylene group or an arylene group. The base resin may be intramolecularly or intermolecularly cross-linked by an unstable group. In the formulas (AL-12) -17 and (AL-12) -18, R ⁶⁴ represents the same as described above, and R ⁶⁸ represents a linear, branched or cyclic alkylene group having 1 to 20 carbon atoms, or an arylene group. And may contain a hetero atom such as an oxygen atom, a sulfur atom or a nitrogen atom. b6 is an integer of 1 to 3.

R ⁶⁴ , R ⁶⁵ , R ⁶⁶ , R ⁶⁷ described above may have a heteroatom such as oxygen, nitrogen, sulfur, etc., specifically, the following formulas (AL-13) -1 to (AL— 13) -7.

  In particular, as the acid labile group of the above formula (AL-12), those having an exo structure represented by the following formula (AL-12) -19 are preferable.

(In the formula, R ⁶⁹ represents a linear, branched or cyclic alkyl group having 1 to 8 carbon atoms or an optionally substituted aryl group having 6 to 20 carbon atoms. R ^{70 to} R ⁷⁵ and R ^78. And R ⁷⁹ each independently represents a hydrogen atom or a monovalent hydrocarbon group such as an alkyl group which may contain a hetero atom having 1 to 15 carbon atoms, and R ⁷⁶ and R ^{77 each} represents a hydrogen atom, or R ⁷⁰ and R ⁷¹ , R ⁷² and R ⁷⁴ , R ⁷² and R ⁷⁵ , R ⁷³ and R ⁷⁵ , R ⁷³ and R ⁷⁹ , R ⁷⁴ and R ⁷⁸ , R ⁷⁶ and R ⁷⁷ , or R ⁷⁷ and R ⁷⁸ are bonded to each other. A ring (particularly an alicyclic ring) may be formed together with the carbon atom to which they are bonded, and in this case, those involved in the formation of the ring are two such as an alkylene group which may contain a hetero atom having 1 to 15 carbon atoms. indicating the valency hydrocarbon group. the R ⁷⁰ and R ^79, R ⁷⁶ and R ^79, or R ⁷² and R ⁷⁴ is nothing in between those bonded to the adjacent carbon Binds not through, may form a double bond. The formula also represents enantiomer.)

Here, the following repeating unit having an exo-body structure represented by the general formula (AL-12) -19
JP-A-2000-327633 discloses an ester monomer for obtaining the above. Specific examples include the following, but are not limited thereto. R ¹¹¹ and R ¹¹² each independently represent a hydrogen atom, a methyl group, —COOCH ₃ , —CH ₂ COOCH ₃ or the like.

  Furthermore, examples of the acid labile group of the above formula (AL-12) include an acid labile group having frangiyl, tetrahydrofurandiyl or oxanorbornanediyl represented by the following formula (AL-12) -20.

(In the formula, R ⁸⁰ and R ⁸¹ each independently represent a monovalent hydrocarbon group such as a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms. Or, R ⁸⁰ and R ⁸¹ are bonded to each other. Then, an aliphatic hydrocarbon ring having 3 to 20 carbon atoms may be formed together with the carbon atom to which they are bonded, and R ⁸² represents a divalent group selected from flangedyl, tetrahydrofurandiyl or oxanorbornanediyl. ⁸³ represents a monovalent hydrocarbon group such as a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms which may contain a hydrogen atom or a hetero atom.)

Repeating units substituted with acid labile groups having frangyl, tetrahydrofurandiyl or oxanorbornanediyl

Examples of the monomer for obtaining the are as follows. R ¹¹² is as described above. In the following formulae, Me represents a methyl group, and Ac represents an acetyl group.

The polymer compound serving as the base of the resist material used in the pattern forming method of the present invention preferably has the repeating unit (a) of the general formula (1) and the repeating unit (b) represented by the general formula (2). Furthermore, a repeating unit (c) derived from a monomer having an adhesive group such as a hydroxy group, a cyano group, a carbonyl group, an ester group, an ether group, a lactone ring, a carboxyl group, or a carboxylic anhydride group is copolymerized. Also good.
Specific examples of the monomer for obtaining the repeating unit (c) include the following.

  Among the repeating units (c), those having an α-trifluoromethyl alcohol group or a carboxyl group improve the alkali dissolution rate after heating of the pattern after development, and it is preferable to copolymerize them. Examples of the repeating unit having a carboxyl group include the following.

  In the repeating units (a), (b) and (c), the ratio of the repeating units is 0 <a <1.0, 0 <b ≦ 0.8, 0.1 ≦ a + b ≦ 1.0, 0 ≦ c <1.0, preferably 0.1 ≦ a ≦ 0.9, 0.1 ≦ b ≦ 0.7, 0.2 ≦ a + b ≦ 1.0, 0 ≦ c ≦ 0.9. . Note that a + b + c = 1.

  Here, for example, a + b = 1 indicates that in the polymer compound containing the repeating units a and b, the total amount of the repeating units a and b is 100 mol% with respect to the total amount of all the repeating units. <1 indicates that the total amount of the repeating units a and b is less than 100 mol% with respect to the total amount of all the repeating units, and has other repeating units c in addition to a and b.

  The polymer compound serving as the base resin of the resist material used in the pattern forming method of the present invention has a polystyrene-reduced weight average molecular weight of 1,000 to 500,000, particularly 2,000 to 30 by gel permeation chromatography (GPC). , 000 is preferable. If the weight average molecular weight is too small, the crosslinking efficiency in thermal crosslinking after development of the resist material is lowered. If the weight average molecular weight is too large, the alkali solubility is lowered, and a trailing phenomenon may easily occur after pattern formation.

  Furthermore, in the high molecular compound used as the base resin of the resist material used in the pattern forming method of the present invention, when the molecular weight distribution (Mw / Mn) is wide, a low molecular weight or high molecular weight polymer exists, so that after exposure, There is a possibility that foreign matter is seen on the pattern or the shape of the pattern is deteriorated. Therefore, since the influence of such molecular weight and molecular weight distribution tends to increase as the pattern rule becomes finer, in order to obtain a resist material suitably used for fine pattern dimensions, the multi-component copolymer used is The molecular weight distribution is preferably from 1.0 to 2.0, particularly preferably from 1.0 to 1.5 and narrow dispersion.

  It is also possible to blend two or more polymers having different composition ratios, molecular weight distributions, and molecular weights.

  In order to synthesize these polymer compounds, one method is to add a monomer having an unsaturated bond to obtain repeating units (a), (b), and (c) in an organic solvent, and add a radical initiator to heat. There is a method of performing polymerization, whereby a polymer compound can be obtained. Examples of the organic solvent used at the time of polymerization include toluene, benzene, tetrahydrofuran, diethyl ether, dioxane and the like. As polymerization initiators, 2,2′-azobisisobutyronitrile (AIBN), 2,2′-azobis (2,4-dimethylvaleronitrile), dimethyl 2,2-azobis (2-methylpropionate) ), Benzoyl peroxide, lauroyl peroxide and the like, and preferably polymerized by heating to 50 to 80 ° C. The reaction time is 2 to 100 hours, preferably 5 to 20 hours. As the acid labile group, those introduced into the monomer may be used as they are, or the acid labile group may be once removed by an acid catalyst and then protected or partially protected.

As described above, the positive resist material is applied onto a substrate to form a resist film, and after heat treatment, a high energy ray is irradiated and exposed to a desired portion of the resist film. After the heat treatment, an alkaline developer is applied. The exposed portion of the resist film is dissolved and developed to form a resist pattern such as a dot pattern, and then an acid is generated in the resist pattern (the unexposed portion due to the high energy rays). The acid labile group of the polymer compound is desorbed (deprotected) and cross-linked. However, in the polymer compound, the acid labile group is desorbed and crosslinked in this manner. The dissolution rate in the alkaline developer is more than 2 nm / second, preferably 3 to 5,000 nm / second, more preferably 4 to 4,000 nm / second. In this case, it is preferably 2 to 250,000 times, particularly 5 to 10,000 times the dissolution rate of the reversal film described later in the alkaline developer, in order to achieve the object of the present invention.
In order to make the polymer compound have such a dissolution rate, the repeating unit (b) having an acid labile group represented by the general formula (2) is 10 mol% or more and 90 mol% or less in all repeating units. In particular, it is preferably 12 mol% or more and 80 mol% or less.

  The resist material used in the pattern forming method of the present invention includes an organic solvent, a compound that generates an acid in response to high energy rays (acid generator), a dissolution controller, a basic compound, a surfactant, if necessary. Other components can be contained.

  The resist material used in the pattern forming method of the present invention may contain an acid generator particularly for functioning as a chemically amplified positive resist material. For example, a compound that generates an acid in response to actinic rays or radiation (light (Acid generator) may be contained. In this case, the compounding amount of the photoacid generator is preferably 0.5 to 30 parts by mass, particularly 1 to 20 parts by mass with respect to 100 parts by mass of the base resin. The component of the photoacid generator may be any compound that generates an acid upon irradiation with high energy rays. Suitable photoacid generators include sulfonium salts, iodonium salts, sulfonyldiazomethane, N-sulfonyloxyimide, oxime-O-sulfonate type acid generators, and the like. Although described in detail below, these can be used alone or in admixture of two or more.

Specific examples of the acid generator are described in paragraphs [0122] to [0142] of JP-A-2008-111103.
The resist material used in the pattern forming method of the present invention can further contain any one or more of an organic solvent, a basic compound, a dissolution controller, a surfactant, and acetylene alcohols.
Specific examples of the organic solvent include paragraphs [0144] to [0145] of JP-A-2008-111103, paragraphs [0146] to [0164] as the basic compound, and paragraphs [0165] to [0166] of the surfactant. ], The dissolution control agent is described in paragraphs [0155] to [0178] of JP-A-2008-122932, and the acetylene alcohols are described in paragraphs [0179] to [0182].

  In addition, it is preferable that the compounding quantity of an organic solvent shall be 100-10,000 mass parts with respect to 100 mass parts of base resins, especially 300-8,000 mass parts. Moreover, it is preferable that the compounding quantity of a basic compound shall be 0.0001-30 mass parts with respect to 100 mass parts of base resins, especially 0.001-20 mass parts.

  Further, a thermal acid generator of ammonium salt as a photoresist material is added in an amount of 0.001 to 20 parts by mass, preferably 0.01 to 10 parts by mass with respect to 100 parts by mass of the base resin of the photoresist material. It is also possible to generate an acid. In this case, the generation of acid, the crosslinking reaction, and the deprotection reaction of the acid labile group proceed simultaneously. The heating conditions are preferably 100 to 300 ° C., particularly 130 to 250 ° C. and preferably 10 to 300 seconds. As a result, a resist film which is dissolved in an alkali and has characteristics necessary for reversing positive / negative that is unnecessary for a solvent and improved in mechanical strength to prevent a pattern from being deformed by heating is formed.

In addition, the following are mentioned as a thermal acid generator of the said ammonium salt.
Wherein R ^101d , R ^101e , R ^101f and R ^101g are each a hydrogen atom, a linear, branched or cyclic alkyl group having 1 to 12 carbon atoms, an alkenyl group, an oxoalkyl group or an oxoalkenyl group, carbon the number 6 to 20 aryl group, or an aralkyl group or an aryl oxoalkyl group having 7 to 12 carbon atoms, some or all of the hydrogen atoms of these groups and may .R ^101d be substituted by an alkoxy group R ^101e or R ^101d and R ^101e and R ^101f may combine to form a ring together with the nitrogen atom to which they are bonded. When forming a ring, R ^101d and R ^101e or R ^101d R ^101e and R ^{101f each} represent an alkylene group having 3 to 10 carbon atoms or a heteroaromatic ring having a nitrogen atom in the formula in the ring, K ⁻ represents a sulfonic acid in which at least one α-position is fluorinated, Or perfluoroalkyl A bromide acid or perfluoroalkyl methide acid.)

Specific examples of K ⁻ include imido acids such as perfluoroalkanesulfonic acid such as triflate and nonaflate, bis (trifluoromethylsulfonyl) imide, bis (perfluoroethylsulfonyl) imide, and bis (perfluorobutylsulfonyl) imide. , Methido acids such as tris (trifluoromethylsulfonyl) methide, tris (perfluoroethylsulfonyl) methide, and sulfonate having a fluoro substituted at the α-position represented by the following general formula (K-1), And sulfonates in which the α-position shown in -2) is fluoro-substituted.

In General Formula (K-1), ^R102 represents a hydrogen atom, a linear, branched or cyclic alkyl group or acyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, or 6 to 6 carbon atoms. 20 aryl groups or aryloxy groups, which may have an ether group, an ester group, a carbonyl group, a lactone ring, or a part or all of the hydrogen atoms of these groups may be substituted with fluorine atoms Good. In general formula (K-2), R ¹⁰³ represents a hydrogen atom, a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, or an aryl having 6 to 20 carbon atoms. It is a group.

  Furthermore, a polymer compound having an amino group and a fluoroalkyl group as repeating units can be added. In this case, the compounding quantity of this high molecular compound can be 0.01-20 mass parts with respect to 100 mass parts of base resins, especially 0.1-15 mass parts. By aligning the polymer compound on the resist surface after coating, it is possible to prevent film loss of the resist pattern after development and to improve the rectangularity. If film loss occurs in the dot pattern after development, image reversal may not be successful. Addition of the following polymer compound is effective for preventing pattern loss.

(In the above formula, R ⁰¹ , R ⁰⁴ and R ⁰⁷ each independently represents a hydrogen atom or a methyl group. X ₁ , Y ₁ and Y ₂ are each independently a single bond, —O—R ⁰⁹ —, —C ( ═O) —O—R ⁰⁹ — or —C (═O) —NH—R ⁰⁹ —, a linear or branched alkylene group having 1 to 4 carbon atoms, or a phenylene group, where R ⁰⁹ is carbon number. 1 to 10 linear, branched or cyclic alkylene groups, which may have an ester group (—COO—) or an ether group (—O—), k is 1 or 2, and k = 1, Y ₁ is a single bond, —O—R ⁰⁹ —, —C (═O) —O—R ⁰⁹ — or —C (═O) —NH—R ⁰⁹ —, having 1 to 4 carbon atoms A linear or branched alkylene group or a phenylene group, and R ⁰⁹ is as described above, and when k = 2, Y ₁ is —O—R ¹⁰¹ ═, —C (═O) —O—. R ¹⁰¹ = or C (= O) -NH-R 101 =, straight or branched further hydrogen atom from an alkylene group releases one leaving group having 1 to 4 carbon atoms, or even one dehydrogenation hydrogen atom from a phenylene group R ¹⁰¹ is a group in which one hydrogen atom is further removed from a linear, branched or cyclic alkylene group having 1 to 10 carbon atoms, and has an ester group or an ether group. R ⁰² and R ⁰³ are the same or different hydrogen atoms, a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, or an alkenyl group having 2 to 20 carbon atoms, a hydroxy group, an ether A group, an ester group, a cyano group, an amino group, a double bond, or a halogen atom, or an aryl group having 6 to 10 carbon atoms, and R ⁰² and R ⁰³ are bonded to form a bond. It may form a ring of 3 to 20 carbon atoms with the nitrogen atom .R ⁰⁵ The number 1 to 12 linear carbon atoms, a branched or cyclic alkylene group, R ⁰⁶ is a hydrogen atom, a fluorine atom, a methyl group, a trifluoromethyl group or difluoromethyl group, or R ⁰⁵ combines with R ⁰⁵ , R ⁰⁶ and the carbon atom to which they are bonded may form an alicyclic ring having 2 to 12 carbon atoms, and the ring has an ether group, an alkylene group substituted with fluorine, or a trifluoromethyl group. R ⁰⁸ is a linear, branched, or cyclic alkyl group having 1 to 20 carbon atoms, substituted with at least one fluorine atom, and an ether group, an ester group, or a sulfonamide group. 0 <d <1.0, 0 ≦ (e−1) <1.0, 0 ≦ (e−2) <1.0, 0 <(e−1) + (e− 2) <1.0, 0.5 ≦ d + (e−1) + (e−2) ≦ 1.0. )

  On the other hand, as the reversal film, a film having a dissolution rate in the alkaline developer used in the reversal process according to the present invention of 0.02 nm / second to 2 nm / second, preferably 0.05 nm / second to 1 nm / second is used. To do. If the dissolution rate is slower than 0.02 nm / second, the inversion film does not dissolve up to the upper part of the first resist pattern, so that the pattern is not inverted or the surface layer of the inverted pattern becomes a head. If it is faster than 2 nm / second, there is a disadvantage that the remaining film of the inversion film is reduced or the hole size of the inversion pattern is increased.

  In this case, in particular, in order to form a trench pattern by appropriately dissolving the film surface during development, the alkali dissolution rate is adjusted to a dissolution rate in the range of 0.05 nm / second to 1 nm / second. If the dissolution rate is faster than this, the film loss during development increases, and if the dissolution rate is slow, the film surface does not dissolve and the trench pattern does not become empty. In order to adjust the dissolution rate appropriately, a unit having an alkali dissolution rate of 1 nm / second or more and a unit of 0.05 nm / second or less are copolymerized and the copolymerization ratio is optimized to obtain a material having an optimal dissolution rate. can do.

  The film (inversion film) having a dissolution rate in the range of 0.02 nm / second or more and 2 nm / second or less in the alkaline developer used in the pattern forming method of the present invention may be a material made of hydrocarbon or silicon. It may be a material. A material based on a polymer having a phenolic hydroxy group, α-trifluoromethylhydroxy group, or carboxyl group is preferably used. As the silicon-containing material, a material having silanol in addition to the alkali-soluble group is preferably used. Examples of the polymer having a phenolic hydroxy group include a cresol novolak resin, a phenol low nucleus, a bisphenol low nucleus, a bisphenol novolak resin, a bisnaphthol low nucleus, a bisnaphthol novolak resin, calixarenes, calix resorcinol, polyhydroxy Styrene, polyhydroxyvinylnaphthalene, polyhydroxyindene and its copolymer, carboxystyrene polymer, carboxyvinylnaphthalene and its copolymer, α-trifluoromethylhydroxy group-containing styrene polymer and its copolymer, methacrylic acid and Examples thereof include a carboxyl group-containing (meth) acrylate polymer and a copolymer thereof, an α-trifluoromethylhydroxy group-containing (meth) acrylate polymer and a copolymer thereof.

  In this case, the alkali dissolution rate of the polymer consisting only of the repeating unit having a phenolic hydroxy group, α-trifluoromethylhydroxy group, and carboxyl group is almost 1 nm / second or more. Copolymerizes with units having a speed of 0.05 nm / sec or less. Examples of the unit having an alkali dissolution rate of 0.05 nm / second or less include, for example, a phenolic hydroxy group, an α-trifluoromethylhydroxy group, a hydrogen atom of a hydroxyl group of a carboxyl group, an alkyl group having 1 to 20 carbon atoms, and a carbon number. Examples thereof include a substituent substituted with an alkenyl group having 3 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an acid labile group. Or, styrenes, indene, indole, chromone, coumarone, acenaphthylene, norbornadiene, norbornenes, vinylnaphthalene, vinylanthracene, vinylcarbazole, vinyl ethers, lactone-containing (meth) acrylates, hydroxy group-containing (meth) acrylates Can be mentioned.

  More specifically, the material for obtaining the polymer for the inversion film specifically has an alkali-soluble group such as a phenolic hydroxy group, a carboxyl group, or an α-trifluoromethylhydroxy group. In order to adjust the alkali dissolution rate, partial protection of the alkali-soluble group, combination with a hardly alkali-soluble group, or the like may be necessary.

  Specific examples of the material having a phenolic hydroxy group include phenol, o-cresol, m-cresol, p-cresol, 2,3-dimethylphenol, 2,5-dimethylphenol, 3,4-dimethylphenol, 3,5-dimethylphenol, 2,4-dimethylphenol, 2,6-dimethylphenol, 2,3,5-trimethylphenol, 3,4,5-trimethylphenol, 2-t-butylphenol, 3-t-butylphenol 4-t-butylphenol, resorcinol, 2-methylresorcinol, 4-methylresorcinol, 5-methylresorcinol, catechol, 4-t-butylcatechol, 2-methoxyphenol, 3-methoxyphenol, 2-propylphenol, 3- Propylphenol, 4-propyl Pyrphenol, 2-isopropylphenol, 3-isopropylphenol, 4-isopropylphenol, 2-methoxy-5-methylphenol, 2-t-butyl-5-methylphenol, pyrogallol, thymol, isothymol, etc. in the presence of aldehydes And novolak resin. Examples of the polymer of the compound having a polymerizable olefin having a phenolic hydroxy group include hydroxystyrene, hydroxyvinylnaphthalene, hydroxyvinylanthracene, hydroxyindene, hydroxyacenaphthylene, and polymers of monomers shown below. .

  A polymer of a monomer for obtaining a repeating unit having a carboxyl group can also be used as a material for forming the inversion film. Specific examples of the monomer include the following.

For partial protection of the phenolic hydroxyl group or carboxyl group for adjusting the alkali dissolution rate, the hydrogen atom of the hydroxyl group or the hydroxyl group of the carboxyl group is substituted with an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms. Substitution with an aryl group having 6 to 20 carbon atoms, an acetyl group, a pivaloyl group or an acid labile group is preferred.
Examples of the acid labile group include those described above.

  In order to adjust the alkali dissolution rate, the alkali-insoluble repeating unit (s-3) can also be copolymerized. As the alkali-insoluble repeating unit, (meth) acrylate of alkyl group or aryl group ester, (meth) acrylate having hydroxy group or lactone, styrene, vinyl naphthalene, vinyl anthracene, vinyl pyrene, vinyl carbazole, indene, acenaphthylene, norbornene , Repeating units derived from norbornadienes, tricyclodecenes, tetracyclododecenes.

As the base polymer for forming the inversion film, a material containing a hydrocarbon having an aromatic group is particularly preferable as the material made of hydrocarbon.
A silicon polymer based on silsesquioxane is preferably used as a material having silicon as the composition for forming a film for reversal from the viewpoint of etching resistance.

In addition, it is preferable that the polystyrene conversion weight average molecular weight by GPC of the said base polymer is 1,000-200,000, especially 1,500-100,000.
The dispersity (Mw / Mn) is preferably 1.0 to 7.0, particularly preferably 1.02 to 5.0.

  As the film forming composition for reversal, in addition to the above base polymer, an alkali slightly soluble material for pattern reversal, an alkali-soluble surfactant for improving the surface alkali dissolution rate, an alkali-soluble etching resistance improver, A basic quencher, an organic solvent, etc. can be used.

  Further, examples of the alkali-soluble material for pattern reversal include phenol groups, malonic acid-substituted fullerenes, and phenolic compound low nuclei. These materials have a high carbon content and also have a function of improving etching resistance. The pattern reversal material may be used alone or in a blend of two or more.

  Specific examples of such materials include phenol compounds disclosed in JP-A-2006-259249, JP-A-2006-259482, JP-A-2006-285095, and JP-A-2006-293298, and JP-A-2007-199653. Bisnaphthol compounds described in the above publication, fluorene compounds having the following phenol groups, 4,4 ′-(9H-fluorene-9-ylidene) bisphenol, 2,2′dimethyl-4,4 ′-(9H-fluorene-9- Ylidene) bisphenol, 2,2′diallyl-4,4 ′-(9H-fluorene-9-ylidene) bisphenol, 2,2′difluoro-4,4 ′-(9H-fluorene-9-ylidene) bisphenol, 2, 2'diphenyl-4,4 '-(9H-fluorene-9-ylidene) bisphenol 2,2′dimethoxy-4,4 ′-(9H-fluorene-9-ylidene) bisphenol, tetrahydrospirobiindene compound, 2,3,2 ′, 3′-tetrahydro- (1,1 ′)-spirobiindene -6,6'-diol, 3,3,3 ', 3'-tetramethyl-2,3,2', 3'-tetrahydro- (1,1 ')-spirobiindene-6,6'-diol 3,3,3 ′, 3 ′, 4,4′-hexamethyl-2,3,2 ′, 3′-tetrahydro- (1,1 ′)-spirobiindene-6,6′-diol, 2, 3,2 ′, 3′-tetrahydro- (1,1 ′)-spirobiindene-5,5′-diol, 5,5′-dimethyl-3,3,3 ′, 3′-tetramethyl-2, 3,2 ′, 3′-tetrahydro- (1,1 ′)-spirobiindene-6,6 - diols, trityl phenol, and the like. These materials can be used as alkali-soluble etching resistance improvers.

  In addition, it is preferable that the addition amount of the said material shall be 0-200 mass parts with respect to 100 mass parts of said base polymers, especially 0-100 mass parts. When mix | blending, it can be 1 mass part or more, Especially 5 mass part or more.

  In the present invention, improving the alkali solubility only on the surface of the pattern reversal film facilitates the dissolution of the pattern reversal film covering up to the top of the positive resist pattern that has been altered to be alkali-soluble. This is effective for improving the dimensional controllability of the converted trench pattern and hole pattern. In order to improve the alkali solubility on the surface, an alkali-soluble surfactant, particularly a fluorosurfactant can be added. As a fluorine-type surfactant, what has either one or both of repeating unit s-1 and s-2 is preferable at least in following General formula (3).

(In the above formula, R ⁸ and R ¹¹ each independently represent a hydrogen atom or a methyl group. N is 1 or 2, and when n = 1, X ₁ is a phenylene group, —O—, —C (= O) —O—R ¹⁴ — or —C (═O) —NH—R ¹⁴ —, wherein R ¹⁴ is a single bond or a linear or branched alkylene group having 1 to 4 carbon atoms, and an ester. In the case where n = 2, X ₁ is a group represented by —C ₆ H ₃ — in which one hydrogen atom is eliminated from the phenylene group, —C (═O) —O—R ⁸¹ ═ or —C (═O) —NH—R ⁸¹ ═, wherein R ⁸¹ is one hydrogen atom removed from a linear, branched or cyclic alkylene group having 1 to 10 carbon atoms. R ⁹ is a single bond, a straight-chain, branched or cyclic alkylene group having 1 to 12 carbon atoms, and R ¹⁰ Is bonded to a hydrogen atom, a fluorine atom, a methyl group, a trifluoromethyl group or a difluoromethyl group, or R ⁹ to form a ring having 3 to 10 carbon atoms (excluding an aromatic ring) together with the carbon atom to which these are bonded. The ring may have an ether group, an alkylene group substituted with fluorine, or a trifluoromethyl group, and X ₂ represents a phenylene group, —O—, —C (═O) —O—. R ¹³ — or —C (═O) —NH—R ¹³ —, wherein R ¹³ is a single bond or a linear or branched alkylene group having 1 to 4 carbon atoms, and an ester group or an ether group. R ¹² is a fluorine atom, a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, which is substituted with at least one fluorine atom, and is an ether group or an ester group or it may have a sulfonamide group .X ₂ If phenylene group, m is an integer of 1 to 5, when X ₂ is other than it, m is 1.)

Specific examples of the monomer for obtaining s-1 can be given below.

(Wherein R ⁸ is the same as described above.)

  Furthermore, the following specific examples can be given as examples of the monomer for obtaining the repeating unit s-2 having an alkyl group substituted with fluorine, represented by s-2 in the general formula (3).

(In the formula, R ¹¹ is the same as described above.)

  The repeating units of s-1 and s-2 can be copolymerized with the alkali-soluble repeating unit having a phenol group or a carboxyl group as described above or the alkali-poorly soluble repeating unit s-3.

  In this case, the ratio of the repeating units of s-1 and s-2 is 0 ≦ (s−1) ≦ 1, 0 ≦ (s−2) ≦ 1, 0 <(s−1) + (s−2). ≦ 1, but preferably 0.1 <(s−1) + (s−2) ≦ 1, more preferably 0.2 <(s−1) + (s−2) ≦ 1. When (s-1) + (s-2) <1, the remaining repeating unit is the repeating unit of s-3.

  In addition, it is preferable that the weight average molecular weight of this alkali-soluble surfactant is 1,000-100,000, especially 2,000-50,000.

  The addition amount of the alkali-soluble surfactant is preferably 0 to 50 parts by mass, particularly preferably 0 to 20 parts by mass with respect to 100 parts by mass of the base polymer. If the amount is too large, the amount of film loss may be excessive or the etching resistance may be reduced. In addition, when mix | blending, it is preferable to set it as 1 mass part or more.

  As the basic quencher, a basic compound similar to the basic compound described in the positive resist material can be used. That is, a basic compound can be added to the pattern reversal film used in the pattern forming method of the present invention in order to prevent acid diffusion from the resist pattern after development. When phenolic compounds and carboxyl group-containing compounds substituted with labile groups are used, the alkali dissolution rate increases due to acid diffusion from the resist pattern and the deprotection reaction, and the size of the inverted pattern increases. As a result, there is a problem that the film is reduced. In order to prevent this, it is effective to add a basic compound. The basic compound added to the resist material and the pattern reversal film may be the same or different.

  The compounding quantity of the said basic compound (basic quencher) is 0-10 mass parts with respect to 100 mass parts of said base polymers, Especially 0-5 mass parts is preferable. In addition, when mix | blending, it is preferable that it is 0.1 mass part or more.

  An onium salt-based acid generator may be added to the inversion film forming composition. When a phenolic material is used as the base polymer of the reversal film-forming composition, the addition of onium salt reduces the alkali dissolution rate due to the dissolution inhibiting effect of the onium salt. Addition of an onium salt is effective for adjusting the alkali dissolution rate.

  The organic solvent used in the pattern reversal film forming composition used in the pattern forming method of the present invention is mixed with a positive resist film (resist pattern) in addition to the organic solvent used in the positive resist material. In order to prevent this, an alcohol having 3 to 10 carbon atoms and an ether compound having 8 to 12 carbon atoms can also be used. Specifically, as alcohol having 3 to 10 carbon atoms, n-propyl alcohol, isopropyl alcohol, 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-pen Tanol, 2-methyl-2-pentanol, 2-methyl-3-pen Nord, 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 1-octanol are mentioned.

Examples of the ether compound having 8 to 12 carbon atoms include di-n-butyl ether, di-isobutyl ether, di-sec-butyl ether, di-n-pentyl ether, diisopentyl ether, di-sec-pentyl ether, di-t. -One or more types of solvent chosen from amyl ether and di-n-hexyl ether are mentioned.
In addition to the above-mentioned solvents, aromatic solvents such as toluene, xylene, and anisole can be mixed.

  The amount of the organic solvent used is preferably 200 to 3,000 parts by mass, particularly 400 to 2,000 parts by mass with respect to 100 parts by mass of the base polymer.

In the patterning method according to the present invention, the positive resist material is applied onto a substrate to form a resist film. In this case, as shown in FIG. 4A, in the present invention, a resist film 30 made of a positive resist material is formed on the substrate 20 to be processed formed on the substrate 10 directly or via an intermediate intervening layer. The thickness of the resist film is preferably 10 to 1,000 nm, particularly 20 to 500 nm. This resist film is heated (pre-baked) before exposure, and as this condition, it is preferable to carry out at 60 to 180 ° C., particularly 70 to 150 ° C. for 10 to 300 seconds, and particularly 15 to 200 seconds.
As the substrate 10, a silicon substrate is generally used. Examples of the substrate to be processed 20 include SiO ₂ , SiN, SiON, SiOC, p-Si, α-Si, TiN, WSi, BPSG, SOG, Cr, CrO, CrON, MoSi, a low dielectric film, and an etching stopper film thereof. It is done. Examples of the intermediate intervening layer include hard masks such as SiO ₂ , SiN, SiON, and p-Si, a lower layer film made of a carbon film, a silicon-containing intermediate film, and an organic antireflection film.

  Examples of the spin-on carbon film include a nortricyclene copolymer described in JP-A No. 2004-205658, a hydrogenated naphthol novolak resin described in JP-A No. 2004-205676, and a naphthol dicyclopentadiene copolymer described in JP-A No. 2004-205665. Coalescence, phenol dicyclopentadiene copolymer described in JP 2004-354554 A, JP 2005-10431 A, fluoreneville phenol novolak described in JP 2005-128509 A, JP 2005-250434 A Acenaphthylene copolymer, indene copolymer described in JP-A-2006-53543, fullerene having a phenol group described in JP-A-2006-227391, JP-A-2006-259249, JP-A-2006-2 No. 3298, bisphenol compound described in JP 2007-316282 A and this novolak resin, bisphenol compound described in JP 2006-259482 A and this novolac resin, and novolak of adamantane phenol compound described in JP 2006-285095 A Resin, hydroxyvinylnaphthalene copolymer described in JP-A-2007-171895, bisnaphthol compound described in JP-A-2007-199653 and this novolak resin, ROMP described in JP-A-2008-26600, JP-A 2008- The resin compound shown by the tricyclopentadiene copolymer of 96684 gazette is mentioned.

  Examples of the spin-on silicon-containing intermediate layer include JP-A No. 2004-310019, JP-A No. 2005-15779, JP-A No. 2005-18054, JP-A No. 2005-352104, JP-A No. 2007-65161, and JP-A No. 2007-65161. It preferably contains an silsesquioxane-based silicon compound disclosed in Japanese Patent Application Publication Nos. 2007-163846, 2007-226170, and 2007-226204, and has an antireflection function.

When the reversal film is made of a hydrocarbon-based material, a carbon film having a carbon content of 75% by mass or more in order from the top of the work substrate, between the work substrate and the positive / negative reversal photoresist film, A film structure for a three-layer resist process for forming an intermediate film containing silicon is preferable. The carbon film may be formed by spin coating, but may be an amorphous carbon film formed by CVD. The intermediate film containing silicon may be an SOG film formed by spin coating or a film selected from SiO ₂ , SiN, SiON, and TiN films formed by CVD or ALD. It has both functions as a membrane.
In addition, an organic antireflection film may be formed between the silicon-containing film and the photoresist film for the purpose of preventing tailing and pattern collapse on the substrate and further reducing substrate reflection.

  When the reversal film is made of a silicon-containing material, a carbon film having a carbon content of 75 mass% or more is formed between the substrate to be processed and the positive / negative reversal photoresist film, and the photoresist is formed thereon. A film is formed. An organic antireflection film may be formed between the carbon film and the photoresist film. In this case, the silicon-containing reversal film functions as a hard mask when processing the carbon film.

  Next, exposure is performed. Here, the exposure is most preferably 193 nm exposure using a high energy beam having a wavelength of 140 to 250 nm, and among these, ArF excimer laser. The exposure may be a dry atmosphere in the air or a nitrogen stream, or may be immersion exposure in water. In ArF immersion lithography, pure water or an alkane or the like having a refractive index of 1 or more and a highly transparent liquid at the exposure wavelength is used as an immersion solvent. In immersion lithography, pure water or other liquid is inserted between a pre-baked resist film and a projection lens. As a result, a lens with an NA of 1.0 or more can be designed, and a finer pattern can be formed. Immersion lithography is an important technique for extending the life of ArF lithography to the 45 nm node. In the case of immersion exposure, pure water rinsing (post-soak) after exposure to remove the water droplet residue remaining on the resist film may be performed, and elution from the resist film is prevented, and the surface lubricity of the film is prevented. In order to increase the thickness, a protective film may be formed on the resist film after pre-baking. As a resist protective film used in immersion lithography, for example, a polymer compound having a 1,1,1,3,3,3-hexafluoro-2-propanol residue that is insoluble in water and dissolved in an alkaline developer is used. A base and a material dissolved in an alcohol solvent having 4 or more carbon atoms, an ether solvent having 8 to 12 carbon atoms, or a mixed solvent thereof is preferable. In this case, the composition for forming a protective film comprises a base resin composed of a repeating unit P-1 serving as a base such as a repeating unit having a 1,1,1,3,3,3-hexafluoro-2-propanol residue. In addition, it is possible to use a base resin obtained by copolymerizing a repeating unit P-2 having a fluoroalkyl group with the repeating unit P-1 serving as the base. Specific examples of the repeating unit P-1 include those obtained from the monomer exemplified in the above s-1, and specific examples of the repeating unit P-2 include those obtained from the monomer exemplified in the above s-2. Can be mentioned. The ratio of these repeating units P-1 and P-2 is as follows: 0 <(P-1) ≦ 1.0, 0 ≦ (P-2) <1.0, 0.3 ≦ (P-1) + (P-2) ≦ 1.0, and the weight average molecular weight of the base resin is 1,000 to 100,000, preferably 2,000 to 50,000.

  In addition, when what does not contain repeating unit P-2 is used as base resin, it is preferable to mix | blend an amine compound with the composition for protective film formation. The amine compound can be selected from those detailed as the basic compound. The compounding amount of the amine compound is preferably 0.01 to 10 parts by mass, particularly 0.02 to 8 parts by mass with respect to 100 parts by mass of the base resin. After the photoresist film is formed, pure water rinsing (post-soak) may be performed to extract an acid generator or the like from the resist film surface or to wash out particles, or to remove water remaining on the film after exposure. Rinse (post-soak) may be performed.

It is preferable to expose so that the exposure amount in exposure is about 1 to 200 mJ / cm ² , preferably about 10 to 100 mJ / cm ² . Next, post-exposure baking (PEB) is performed on a hot plate at 60 to 150 ° C. for 1 to 5 minutes, preferably 80 to 120 ° C. for 1 to 3 minutes.

  Further, 0.1 to 5% by weight, preferably 2 to 3% by weight, using an aqueous developer such as tetramethylammonium hydroxide (TMAH) for 0.1 to 3 minutes, preferably 0.5 to 2 minutes. The target resist pattern 30a is formed on the substrate by development by a conventional method such as a dip method, a paddle method, or a spray method (see FIG. 4B).

  By using a mask having a lattice pattern, a dot pattern having a half pitch size of 38 × 38 nm to 100 × 100 nm, particularly 40 × 40 nm to 80 × 80 nm can be formed. The size of the dot pattern depends on the NA of the lens of the exposure machine. If an exposure machine with a NA of 1.35 is used, a dot with a half pitch of 38 nm can be formed as the minimum dimension. The dot pattern may have the same length in the vertical and horizontal directions, or one of them may be a long-axis dot pattern with a long length. The method of forming the dot pattern is not particularly limited, but there is a method of adopting a method of forming a dot pattern by performing exposure using a phase shift mask of a lattice pattern on the resist film with high energy rays and developing the resist film. The finest half pitch holes can be formed.

  Conventionally, when forming dots with such a fine pitch, two exposures using two masks by double dipole lithography were necessary. That is, in the first exposure, the X-direction line is exposed with dipole illumination, the mask is changed, and in the second exposure, the Y-direction line is exposed with dipole illumination. In this case, the throughput decreases due to the replacement of the mask and the accompanying alignment. In addition, the alignment misalignment between the two exposures leads to the positional deviation of the hole to be finally formed. When the position of the hole and the position of the line connected to the hole are different, a connection failure is caused. Therefore, when exposure is performed with a double dipole, a very high alignment accuracy is required.

  The pattern formed by the double exposure of the double dipole causes a positional deviation of the second exposure, whereas the pattern forming method of the present invention does not cause a positional deviation because only one exposure is required. In addition, there is no need to replace the mask and only one exposure is required, which has the advantage of high throughput.

  Next, baking (PEB) is performed, and a dot pattern is formed by development. A random pitch dot pattern is formed by one development (see FIG. 4B).

Next, the acid labile group of the polymer compound (base resin) in the pattern is eliminated and the polymer compound is crosslinked to form a crosslinked pattern 30b (see FIG. 4C). Acid and heating are required for elimination and crosslinking of the acid labile group of the polymer compound in the resist pattern. In this case, after the acid is generated, deprotection and crosslinking of the acid labile group are simultaneously performed by heating. In order to generate the acid, there is a method in which the photoacid generator is decomposed by flood exposure of the wafer (pattern) after development. The exposure wavelength of the flood exposure is a wavelength of 180 to 400 nm and an exposure amount of 10 mJ / cm ^{2 to 1} J / cm ² . Irradiation with excimer lasers or excimer lamps with wavelengths less than 180 nm, particularly 172 nm, 146 nm, and 122 nm, not only generates acid from the photoacid generator, but also promotes the crosslinking reaction by light irradiation, and alkali dissolution by excessive crosslinking It is not preferable because the speed is reduced. As the flood exposure wavelength, an ArF excimer laser having a wavelength longer than 193 nm, a 222 nm KrCl excimer lamp, a 248 nm KrF excimer laser, a 254 nm low-pressure mercury lamp, a 308 nm XeCl excimer lamp, and a 365 nm i-line are preferably used. It is also possible to add an ammonium salt thermal acid generator to the positive resist material and generate an acid by heating. In this case, the generation of acid and the crosslinking reaction proceed simultaneously. The heating conditions are 150 to 400 ° C., particularly 160 to 300 ° C., preferably 10 to 300 seconds. As a result, a crosslinked resist pattern insoluble in the solvent of the reversal film forming composition is formed. In order to generate an acid by exposure, a new exposure apparatus is required. Therefore, it is preferable to add a thermal acid generator as a resist material and advance deprotection and crosslinking reaction only by heating.

  Next, as shown in FIG. 4D, a reversal film 40b is formed by applying a reversal film-forming composition so as to cover the crosslinked resist pattern 30b. In this case, the thickness of the inversion film 40 is preferably equal to the height of the resist pattern or in a range of ± 30 nm.

  Next, the surface portion of the reversal film 40 is dissolved using the alkaline developer to expose the cross-linked resist pattern 30b, whereby the dissolution rate of the cross-linked resist pattern 30b in the alkaline developer is changed. Since the dissolution rate of the crosslinked resist pattern 30b is selectively dissolved and dissolved and disappears, the inverted resist pattern 30b is inverted on the inversion film 40 as shown in FIG. 4E. 40a is formed. In this case, if the resist pattern is a dot pattern, a hole pattern is formed as an inverted pattern. The hole size can be reduced by heating the hole pattern after inversion. The baking temperature is 70 to 180 ° C., preferably 80 to 170 ° C., and the time is 10 to 300 seconds.

  It is also possible to apply a RELACS method in which a shrinking agent is applied on the hole pattern after inversion and the hole pattern is reduced by baking. Japanese Patent No. 3071401, Japanese Patent Laid-Open No. 2001-228616, Japanese Patent Laid-Open No. 2004-86203 The materials described in Japanese Patent Laid-Open No. 2004-294992, Japanese Patent Laid-Open No. 2007-206728, and International Publication No. 2005/008340 can be used.

  That is, polyacrylic acid, polyvinyl alcohol, polyvinyl acetal, polyvinyl pyrrolidone, polyethyleneimine, polyethylene oxide, polyvinylamine, polyallylamine, styrene maleic acid copolymer, poly N-vinylformamide, polyoxazoline, melamine resin, urea as the base polymer A water-soluble resin mainly composed of a resin, an alkyd resin, a sulfonamide, a carbonamide or the like is used, and a composition in which the crosslinking agent is dissolved in water or alcohol is used as a shrink agent.

  The shrink agent is attached to the film after reversal by baking after the application of the shrink agent, and the excess shrink agent is peeled off with water, alcohol, an alkaline developer and a mixture thereof. The baking temperature is 70 to 170 ° C., preferably 80 to 150 ° C., and the time is 10 to 300 seconds.

As a reversal film used in the pattern forming method of the present invention, the use of a phenol-based material has an advantage that thermal flow and RELACS can be easily shrunk. In the case of a positive resist using a phenolic material, the glass transition point of the film changes depending on the difference in the amount of partial elimination of acid labile groups between dense holes and isolated holes. The dense hole is greatly affected by the covering light, and the partial deprotection proceeds more than the isolated hole, so that the glass transition point is increased, and the deformation amount due to the flow is reduced, so that the reduction amount of the hole is reduced.
Since the reversal film material used in the pattern forming method of the present invention is not the formation of a pattern by light exposure, there is no difference in the glass transition point between the dense pattern and the isolated pattern. Therefore, there is an advantage that there is no difference in the reduction amount between the dense hole and the isolated hole.

  Further, as shown in FIG. 4 (F), when there is an intermediate intervening layer such as a hard mask using the reversal pattern 40a as a mask, the intermediate intervening layer is etched, and the substrate 20 to be processed is further etched. In this case, the intermediate intervening layer such as a hard mask can be etched by dry etching using a fluorocarbon or halogen gas, and the etching of the substrate to be processed has an etching selectivity with respect to the hard mask. The etching gas and conditions for the etching can be selected as appropriate, and can be performed by dry etching using a gas such as chlorofluorocarbon, halogen, oxygen, and hydrogen. Next, the cross-linked resist film and the second resist film are removed. These removals may be performed after etching of the intermediate intervening layer such as a hard mask. The cross-linked resist film can be removed by dry etching such as oxygen and radicals, and the second resist film can be removed in the same manner as described above, or an amine solvent, or an organic solvent such as sulfuric acid / hydrogen peroxide solution. It can carry out with stripping solutions, such as.

  EXAMPLES Hereinafter, although a synthesis example, an Example, and a comparative example are shown and this invention is demonstrated concretely, this invention is not restrict | limited to the following Example etc. In addition, a weight average molecular weight (Mw) shows the polystyrene conversion weight average molecular weight by GPC.

[Synthesis example]
As a polymer compound used for the film for reversal, each monomer is combined and subjected to a copolymerization reaction in a tetrahydrofuran solvent, crystallized in methanol, further washed with hexane, isolated and dried, and the composition shown below The high molecular compound (Polymer 1) was obtained. The phenol group of the monomer was substituted with an acetoxy group and converted to a phenol group by alkali hydrolysis after polymerization. The composition of the obtained polymer compound was confirmed by ¹ H-NMR, and the molecular weight and dispersity were confirmed by gel permeation chromatography.

Polymer 1
Molecular weight (Mw) = 9,300
Dispersity (Mw / Mn) = 1.88

The polymer 1, the basic compound, and the solvent were added to prepare a pattern reversal film-forming composition having the composition shown in Table 1. To the solvent, 100 ppm of a fluorosurfactant FC-4430 (manufactured by Sumitomo 3M Limited) was added.
A pattern reversal film-forming composition is applied to a HMDS (hexamethyldisilazane) primed 8-inch silicon substrate and baked at 110 ° C. for 60 seconds to form a pattern reversal film (IROC-1) having a thickness of 60 nm. did. This was developed with a 2.38 mass% developer solution of tetramethylammonium hydroxide (TMAH) for 30 seconds, the amount of film loss due to development was determined, and the dissolution rate per second was calculated. The results are shown in Table 1.

Basic compound: Basic quencher 1 (see structural formula below)

Organic solvent: PGMEA (propylene glycol monomethyl ether acetate)

Preparation of positive resist material and composition for forming an alkali-soluble protective film A 0.2 μm size solution prepared by dissolving the compositions shown in Tables 2 and 3 below using the following polymer compounds (resist polymer 1 and protective film polymer). A resist solution and a composition solution for forming a protective film were prepared by filtration using a filter.
Each composition in Tables 2 and 3 is as follows.

Acid generator: PAG1 (see structural formula below)

Resist polymer 1
Molecular weight (Mw) = 8,310
Dispersity (Mw / Mn) = 1.73

Protective film polymer
Molecular weight (Mw) = 8,800
Dispersity (Mw / Mn) = 1.69

Basic compound: Basic quencher 2 (see structural formula below)

Thermal acid generator: TAG1 (see structural formula below)
Organic solvent: PGMEA (propylene glycol monomethyl ether acetate)

Measurement of change in film thickness and solvent dissolution rate by solvent after high-temperature baking A resist material prepared with the composition shown in Table 2 above was spin-coated on a silicon wafer, and baked at 190 ° C. for 60 seconds using a hot plate. The thickness of the film was 150 nm. Solvent is dispensed on the resist film for 30 seconds, then rotated at 2,000 rpm for 30 seconds, the solvent is shaken off, the solvent is dried by baking at 100 ° C. for 60 seconds, and the change in film thickness after baking at 190 ° C. Was determined using a film thickness meter.
Next, the alkali dissolution rate of the film after baking at 190 ° C. was determined for the alkali dissolution rate in a 2.38 mass% TMAH aqueous solution using Resotech Japan Co., Ltd. resist development analyzer RDA-790. The results are shown in Table 4.

Organic solvent: PGMEA (propylene glycol monomethyl ether acetate)

[Examples 1 and 2, Comparative Examples 1 and 2]
Evaluation of ArF exposure patterning Resist materials prepared with the compositions shown in Table 2 above were formed on a silicon wafer with a spin-on carbon film ODL-50 (carbon content of 80% by mass) manufactured by Shin-Etsu Chemical Co., Ltd., 200 nm above it. A silicon-containing spin-on hard mask SHB-A941 (silicon content is 43% by mass) is spin-coated on a substrate for a trilayer process having a film thickness of 35 nm and is heated at 100 ° C. for 60 seconds using a hot plate. The resist film was baked to a thickness of 100 nm. A protective film-forming composition (TC-1) shown in Table 3 was spin-coated thereon, and baked at 90 ° C. for 60 seconds, so that the thickness of the protective film was 50 nm.
In Example 1, an ArF excimer laser immersion scanner (manufactured by Nikon Corporation, NSR-S610C, NA 1.30, σ0.98 / 0.78, cross pole opening 20 degrees, azimuthally polarized illumination, shown in FIG. 34) (6% half-tone phase shift mask with dimensions and layout), and after exposure, baked (PEB) at 100 ° C. for 60 seconds, and developed with 2.38 mass% TMAH aqueous solution for 30 seconds.
As Example 2, an ArF excimer laser immersion scanner (manufactured by Nikon Corporation, NSR-S610C, NA1.30, σ0.98 / 0.78, dipole, having the same film configuration as in Example 1 and using the same mask) Two exposures of the X direction dipole and the Y direction dipole were performed continuously using an aperture of 20 degrees and azimuthally polarized illumination), and after exposure, baked at 100 ° C. for 60 seconds (PEB), and 2.38 mass% TMAH Development was carried out with an aqueous solution for 30 seconds.
As Comparative Example 1, using the same film configuration and exposure machine as in Example 1, using the mask shown in FIG. 35, NA 1.30, σ 0.98 / 0.78, cross pole aperture 20 degrees, azimuthally polarized illumination And the same post-exposure processing was performed.
In Examples 1 and 2, A-1, B-1, C-1, D-1 on the mask shown in FIG. 34, and in Comparative Example 1, A-2, B-2 on the mask shown in FIG. The dimensions of the developed dot pattern formed at the locations of C-2 and D-2, the dot pattern after heating, and the hole pattern obtained by reversing the image are obtained by TDSEM (S-9380) manufactured by Hitachi High-Technologies Corporation. And observed. The results are shown in Table 5.

  As Comparative Example 2, the hole pattern was exposed using a lattice mask having a pitch of 90 nm and a line width of 25 nm (hole size of 65 nm) shown in FIG. . After exposure, it was baked (PEB) at 100 ° C. for 60 seconds, and developed with a 2.38 mass% TMAH aqueous solution for 30 seconds. When the size of the hole was observed using TDSEM (S-9380) manufactured by Hitachi High-Technologies Corporation, the minimum dimension resolved was 50 nm, and holes smaller than this were not resolved.

  From the results shown in Table 5, in the pattern forming method of Example 1, a hole pattern of about 40 nm was opened from 1: 1 dense to isolated with a pitch of 90 nm in one exposure. In Example 2, a hole pattern of about 40 nm was opened from 1: 1 compaction with a pitch of 90 nm to isolation by two double dipole exposures. On the other hand, in the conventional method (Comparative Example 1), the dimensional difference between the dense pattern and the isolated pattern was increased, and the film thickness of the dot pattern after development was reduced. Therefore, the hole pattern after the reversal operation did not open. Further, holes having a pitch of 90 nm were resolved by exposure and development by a conventional method, but the size of the smallest hole was 50 nm.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

DESCRIPTION OF SYMBOLS 10 Substrate 20 Substrate 30 Resist film 30a Resist pattern 30b Cross-linked resist pattern 40 Reverse film 40a Reverse pattern

Claims (28)

A resin having a repeating unit having a structure having an acid labile group that is eliminated by an acid on the substrate to be processed, which becomes soluble in an alkaline developer by the elimination of the acid labile group, exposure of high energy rays Apply a chemically amplified positive resist material containing a photoacid generator that generates acid by heat or a thermal acid generator that generates acid by heating, and an organic solvent, and remove unnecessary solvents by pre-baking. Forming a resist film, a lattice-shaped first shifter having a line width of half a pitch or less on the resist film, and a width on the wafer of 2 to 100 nm on the first shifter than the width of the first shifter. High energy rays are exposed using a phase shift mask in which second shifters having a thick dot pattern are arranged, heated after the exposure, and the acid generated from the acid generator by the exposure is removed from the resin. To act on Sadamoto, after performing the elimination reaction in the acid labile groups of the resin in the exposed area, the exposure step to obtain a positive pattern and then developed with an alkaline developing solution, the positive pattern obtained in about該工and by / or heat to the acid and / or heat, the acid labile group of the resin of the positive pattern of desorbed to improve the alkaline solubility and lose solubility in an alkaline wet etchant to the resin not to form a cross-linked in the range, the step of film loss when allowed to touch 30 seconds in an organic solvent used in the reversal film-forming composition to said positive pattern gives the following solvent resistance 10 nm, the organic forming a reversal film using a reversal film forming composition is a solvent solution, the positive-negative inversion comprising the step of dissolving and removing the positive pattern of the crosslinking is formed by an alkaline wet etchant There was a pattern forming method.   The pattern forming method according to claim 1, wherein the dots of the second shifter are arranged on the intersection of the first shifter.   3. The pattern forming method according to claim 1, wherein the shape of the second shifter is a quadrangle, a quadrilateral or more polygon, or a circle.   The pattern forming method according to claim 1, wherein a dot pattern of the resist after development is formed only on the dot portion of the second shifter.   5. The pattern forming method according to claim 1, wherein the shifter is a halftone phase shift mask having a transmittance of 3 to 15%.   The width of the first shifter is 1/3 or less of the pitch, and the second shifter is arranged with dots that are 2-100 nm thicker on the wafer than the line width of the first shifter. 6. The pattern forming method according to claim 1, wherein exposure is performed using a phase shift mask.   The dissolution rate of the crosslink-forming positive pattern obtained in the step of imparting resistance to the organic solvent used in the reversal film-forming composition to the resist pattern is 2.38 mass% tetramethylammonium hydroxy. When the organic solvent used in the reversal film forming composition is etched with an aqueous solution of TMAH, propylene glycol monomethyl ether acetate, cyclohexanone, ethyl lactate, A single or mixed solvent containing one or more selected from propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, heptanone, and the above The resistance to the solvent used in the diverting film forming composition is 10 nm or less when the cross-linking positive pattern is brought into contact with the solvent used in the reversing film forming composition for 30 seconds. The pattern forming method using positive / negative reversal according to any one of claims 1 to 6, wherein the pattern forming method has solvent resistance.   The pattern forming method using positive / negative reversal according to any one of claims 1 to 7, wherein the reversal film-forming composition contains a resin containing a monomer unit having an aromatic skeleton or an alicyclic skeleton.   Between the step of forming a film for reversal using the composition for forming a film for reversal and the step of dissolving and removing the positive pattern for crosslinking formation with an alkaline wet etchant, the film was laminated on the positive pattern for crosslinking formation. The pattern forming method using positive / negative reversal according to claim 1, comprising a step of removing the reversal film.   10. The pattern forming method using positive / negative reversal according to claim 9, wherein the step of removing the reversal film laminated on the positive pattern is wet etching.   The reversal film is a material that has a lower dissolution rate and exhibits solubility than the cross-linked positive pattern after the step of imparting resistance to the organic solvent when treated with an alkaline wet etchant, and further comprises the wet etch 11. The step of removing the reversal film laminated on the cross-linking positive type pattern and the step of dissolving and removing the positive type pattern with the alkaline wet etching solution are simultaneously performed using an alkaline wet etching solution. The pattern formation method using the positive / negative reversal described.   The positive / negative reversal method according to claim 11, wherein the reversal film has a dissolution rate of 0.02 nm / second or more and 2 nm / second or less when etched with a 2.38 mass% tetramethylammonium hydroxide (TMAH) aqueous solution. Pattern formation method.   13. The positive / negative reversal according to claim 1, wherein the chemically amplified positive resist material contains a component that generates an acid by heating in a step of imparting resistance to an organic solvent to the resist pattern. The pattern forming method used.   The pattern forming method using positive / negative reversal according to claim 13, wherein the component that generates acid by heating is a thermal acid generator added separately from the photoacid generator. The pattern formation method according to claim 14, wherein the thermal acid generator is represented by the following general formula (P1a-2).
Wherein R ^101d , R ^101e , R ^101f and R ^101g are each a hydrogen atom, a linear, branched or cyclic alkyl group having 1 to 12 carbon atoms, an alkenyl group, an oxoalkyl group or an oxoalkenyl group, carbon the number 6 to 20 aryl group, or an aralkyl group or an aryl oxoalkyl group having 7 to 12 carbon atoms, some or all of the hydrogen atoms of these groups and may .R ^101d be substituted by an alkoxy group R ^101e or R ^101d and R ^101e and R ^101f may combine to form a ring together with the nitrogen atom to which they are bonded. When forming a ring, R ^101d and R ^101e or R ^101d R ^101e and R ^{101f each} represent an alkylene group having 3 to 10 carbon atoms or a heteroaromatic ring having a nitrogen atom in the formula in the ring, K ⁻ represents a sulfonic acid in which at least one α-position is fluorinated, Or perfluoroalkyl A bromide acid or perfluoroalkyl methide acid.)   16. The chemically amplified positive resist material is a positive resist material containing a resin having a repeating unit having a lactone ring as the resin and a repeating unit having an acid labile group that is eliminated by an acid. The pattern formation method using positive / negative inversion of any one of these. The positive resist material is a positive resist material containing a resin having a repeating unit having a 7-oxanorbornane ring and a repeating unit having an acid labile group that is eliminated by an acid. When the acid labile group of the resin in the positive pattern is eliminated by generating and applying heat, the resin crosslinking in the positive pattern and the acid labile group are eliminated simultaneously. Item 17. A pattern forming method using positive / negative reversal according to Item 16 . The pattern forming method using positive / negative reversal according to claim 17 , wherein the repeating unit having a 7-oxanorbornane ring is a repeating unit (a) represented by the following general formula (1).
(In the formula, R ¹ represents a hydrogen atom or a methyl group. R ² is a single bond or a linear, branched or cyclic alkylene group having 1 to 6 carbon atoms, and has an ether group or an ester group. may be, the number of 1 to 6 linear carbon atoms, for branched or cyclic alkylene group, the carbon atom linked to the ester group in the formula is a primary or secondary .R ^3, R ^4, R ⁵ is a hydrogen atom or a linear, branched or cyclic alkyl group having 1 to 6 carbon atoms, and a is in the range of 0 <a <1.0. The pattern forming method according to any one of claims 16 to 18 , wherein the repeating unit having an acid labile group that is eliminated by an acid is the repeating unit (b) represented by the following general formula (2).
(In the formula, R ⁶ represents a hydrogen atom or a methyl group, and R ⁷ represents an acid labile group. B is 0 <b ≦ 0.8.) The pattern forming method according to claim 19 , wherein the acid labile group of R ^{7 is} an acid labile group having an alicyclic structure which is eliminated by an acid. The positive pattern are those containing a dot pattern, the inverted in the resulting pattern pattern formation method using the positive-negative inversion of any one of claims 1 to 20 is intended to include a hole pattern. The positive pattern is intended to include both the isolated dot pattern with dense dot pattern, according to any one of the pattern obtained by the inversion dense hole pattern and an isolated hole pattern is intended to include claims 1 to 21 Pattern formation method using positive / negative reversal. The positive pattern exposes a dense dot pattern, exposes an unnecessary dot pattern portion to form a dense dot pattern and an isolated dot pattern, and forms a dense hole pattern and an isolated hole pattern by the positive / negative reversal. The pattern forming method according to claim 22 . A chemically amplified positive resist material containing a resin having a repeating unit having a structure having an acid labile group that is eliminated by an acid is applied on a substrate to be processed, and unnecessary solvent is removed by heating to form a resist film. Forming a protective film on the resist film, removing unnecessary solvent by heating to form a protective film, water or a refractive index of 1 or more between the resist film and the projection lens The resist film is subjected to immersion exposure of a dense pattern of high energy rays through a transparent liquid, and the unexposed portion of an unnecessary dense pattern is subjected to immersion exposure, and the acid generated by exposure by heating after exposure is acidified. It is obtained in the process of obtaining a positive pattern by acting on an unstable group, causing the acid labile group of the resin in the exposed area to undergo elimination reaction, and then developing with an alkaline developer. Cash register In addition, the acid labile groups of the above resin in the pattern are eliminated, and the resin is crosslinked to the extent that it does not lose its solubility in alkaline wet etching solution. A step of giving a solvent resistance of 10 nm or less when the film is brought into contact with the organic solvent for 30 seconds , a step of forming a reversal film using the reversal film-forming composition as the organic solvent solution, The pattern forming method using positive / negative reversal according to any one of claims 1 to 23 , including a step of dissolving and removing the positive pattern with an alkaline wet etching solution. The pattern forming method according to claim 24 , wherein the composition for forming a protective film contains an amine compound. A carbon film having a carbon content of 75% by mass or more is formed on a substrate to be processed, an intermediate film containing silicon is formed thereon, and the chemically amplified positive resist material is coated thereon and inverted. The pattern forming method according to any one of claims 1 to 25 , wherein the coating film is made of a hydrocarbon-based material. A carbon film having a carbon content of 75% by mass or more is formed on a substrate to be processed, and the chemically amplified positive resist material is coated thereon, and the inversion film is made of a material containing silicon. the pattern forming method according to any one of claims 1 to 25, characterized. A carbon film having a carbon content of 75% by mass or more is formed on a substrate to be processed, an organic antireflection film is formed thereon, and the chemically amplified positive resist material is coated thereon, and a reversal film 28. The pattern forming method according to claim 27 , wherein the pattern forming method is made of a material containing silicon.