JP5085569B2 - Resist underlayer film forming method and pattern forming method using the same - Google Patents

Description

The present invention relates to a resist underlayer film forming method for forming a resist underlayer film effective as an antireflection film used for microfabrication in a manufacturing process of a semiconductor element and the like, and far ultraviolet ray and KrF excimer laser light (248 nm) using the same. , ArF excimer laser light (193 nm), F ₂ laser light (157 nm), Kr ₂ laser light (146 nm), Ar ₂ laser light (126 nm), soft X-ray (EUV, 13.5 nm), electron beam (EB), The present invention relates to a resist pattern forming method suitable for X-ray exposure or the like.

  In recent years, with the increasing integration and speed of LSIs, there is a need for finer pattern rules. In lithography using light exposure, which is currently used as a general-purpose technology, the essence derived from the wavelength of the light source The resolution limit is approaching.

  As a light source for lithography used in forming a resist pattern, light exposure using a mercury lamp g-line (436 nm) or i-line (365 nm) as a light source is widely used, and as a means for further miniaturization, A method of shortening the wavelength of exposure light has been considered effective. For this reason, a short wavelength KrF excimer laser (248 nm) was used as an exposure light source in place of the i-line (365 nm) in the mass production process of the 64-Mbit DRAM processing method. However, in order to manufacture a DRAM having a degree of integration of 1G or more, which requires a finer processing technique (processing dimension is 0.13 μm or less), a light source with a shorter wavelength is required, and in particular, an ArF excimer laser (193 nm) is used. Lithography has been studied.

  On the other hand, conventionally, it is known that a two-layer process is excellent for forming a pattern with a high aspect ratio on a stepped substrate, and further, for developing a two-layer resist film with a general alkali developer. Requires a high molecular silicone compound having a hydrophilic group such as a hydroxy group or a carboxyl group.

As the silicone-based chemically amplified positive resist material, a base resin in which a part of the phenolic hydroxyl group of polyhydroxybenzylsilsesquioxane, which is a stable alkali-soluble silicone polymer, is protected with a t-Boc group is used. A silicone-based chemically amplified positive resist material for a KrF excimer laser, which combines an acid generator and an acid generator, has been proposed (see Patent Document 1, Non-Patent Document 1, etc.). For ArF excimer lasers, positive resist materials based on silsesquioxane in which cyclohexylcarboxylic acid is substituted with an acid labile group have been proposed (Patent Documents 2 and 3, Non-Patent Document 2). Etc.). Furthermore, for F ₂ lasers, positive resist materials based on silsesquioxane having hexafluoroisopropanol as a soluble group have been proposed (see Patent Document 4, etc.). The above polymer contains polysilsesquioxane having a ladder skeleton formed by condensation polymerization of trialkoxysilane or trihalogenated silane in the main chain.

  As a resist base polymer in which silicon is pendant on a side chain, a silicon-containing (meth) acrylic ester polymer has been proposed (see Patent Document 5, Non-Patent Document 3, etc.).

  The resist underlayer film of the two-layer process is a hydrocarbon compound that can be etched with oxygen gas, and further needs to have high etching resistance because it serves as a mask for etching the underlying substrate. In oxygen gas etching, it is necessary to be composed only of hydrocarbons that do not contain silicon atoms. In addition, in order to improve the line width controllability of the upper silicon-containing resist film and reduce the pattern sidewall irregularities and pattern collapse due to standing waves, it also has a function as an antireflection film, specifically It is necessary to suppress the reflectance from the resist lower layer film into the resist upper layer film to 1% or less.

  Here, the results of calculating the reflectance up to a maximum film thickness of 500 nm are shown in FIGS. Assuming that the exposure wavelength is 193 nm, the n value of the resist upper layer film is 1.74, and the k value is 0.02, the k value of the resist lower layer film is fixed at 0.3 in FIG. 0.0 to 2.0, and the horizontal axis represents the substrate reflectance when the film thickness is varied in the range of 0 to 500 nm. Assuming a resist underlayer film for a two-layer process having a film thickness of 300 nm or more, the reflectivity is in the range of n to 1.6 to 1.9, which has a refractive index that is the same as or slightly higher than the resist upper layer film. There is an optimum value that can be reduced to 1% or less.

  FIG. 3 shows the reflectance when the n value of the resist underlayer film is fixed to 1.5 and the k value is varied in the range of 0 to 0.8. When a resist underlayer film for a two-layer process having a film thickness of 300 nm or more is assumed, the reflectance can be reduced to 1% or less in the range of k value from 0.24 to 0.15. On the other hand, the optimum k value of an antireflection film for a single layer resist used in a thin film of about 40 nm is 0.4 to 0.5, and the optimum k value of a resist underlayer film for a two layer process used at 300 nm or more is Is different. It has been shown that a resist underlayer film for a two-layer process requires a lower k value, that is, a more transparent resist underlayer film.

  Here, as a resist underlayer film material for a wavelength of 193 nm, a copolymer of polyhydroxystyrene and an acrylate ester has been studied as introduced in Non-Patent Document 4. Polyhydroxystyrene has a very strong absorption at 193 nm, and the k value alone is a high value of around 0.6. Therefore, the k value is adjusted to around 0.25 by copolymerizing with an acrylate ester having a k value of almost 0.

  However, with respect to polyhydroxystyrene, the etching resistance of acrylate esters in substrate etching is weak, and a significant proportion of acrylate esters must be copolymerized to lower the k value, resulting in substrate etching. Resistance is significantly reduced. The resistance to etching appears not only in the etching rate but also in the occurrence of surface roughness after etching. The increase in surface roughness after etching becomes more prominent due to the copolymerization of acrylic acid ester.

  On the other hand, a three-layer process has been proposed in which a single-layer resist containing no silicon is formed as a resist upper layer film, a resist intermediate layer film containing silicon underneath, and a resist underlayer film of an organic film thereunder is further laminated (for example, Non-patent document 5). In general, a single-layer resist has better resolution than a silicon-containing resist, and a high-resolution single-layer resist can be used as an exposure imaging layer in a three-layer process. As the resist intermediate layer film, a spin-on-glass (SOG) film is used, and many SOG films have been proposed.

  Here, the optimum optical constant of the lower layer film for suppressing the substrate reflection in the three-layer process is different from that in the two-layer process. The purpose of suppressing the substrate reflection as much as possible, specifically, to reduce it to 1% or less, is the same in both the two-layer process and the three-layer process, but the two-layer process has an antireflection effect only on the resist underlayer film. On the other hand, in the three-layer process, one or both of the resist intermediate layer film and the resist underlayer film can have an antireflection effect.

Patent Document 6 and Patent Document 7 propose silicon-containing layer materials imparted with an antireflection effect. In general, a multilayer antireflection film has a higher antireflection effect than a single-layer antireflection film, and is widely used industrially as an antireflection film for optical materials. By imparting an antireflection effect to both the resist intermediate layer film and the resist underlayer film, a high antireflection effect can be obtained.
If the silicon-containing resist intermediate layer film can have a function as an antireflection film in the three-layer process, the resist underlayer film need not have the highest effect as an antireflection film as in the two-layer process. The resist underlayer film in the case of the three-layer process is required to have higher etching resistance in substrate processing than the effect as an antireflection film.
Therefore, a novolak resin containing a large amount of aromatic groups and having high etching resistance has been used as a resist underlayer film for a three-layer process.

Here, FIG. 4 shows the substrate reflectivity when the k value of the resist intermediate layer film is changed.
A sufficient antireflection effect of 1% or less can be obtained by a low value of 0.2 or less as the k value of the resist intermediate layer film and an appropriate film thickness setting.
In order to suppress reflection to 1% or less at a film thickness of 100 nm or less as a normal antireflection film, the k value is required to be 0.2 or more (see FIG. 3). As the resist intermediate layer film of the three-layer resist film that can be suppressed, the k value lower than 0.2 is the optimum value.

Next, FIG. 5 and FIG. 6 show the reflectance change when the thickness of the resist intermediate layer film and the resist lower layer film is changed when the k value of the resist lower layer film is 0.2 and 0.6. Show.
The resist underlayer film having a k value of 0.2 in FIG. 5 assumes a resist underlayer film optimized for a two-layer process, and the resist underlayer film in FIG. 6 having a k value of 0.6 is at a wavelength of 193 nm. The value is close to the k value of novolak and polyhydroxystyrene.
Although the film thickness of the resist underlayer film varies depending on the topography of the substrate, the film thickness of the resist intermediate layer film hardly varies, and it is considered that the resist can be applied with a set film thickness.

  Here, the higher the k value of the resist underlayer film (in the case of 0.6), the reflection can be suppressed to 1% or less with a thinner film. When the k value of the resist underlayer film is 0.2, the film thickness of the resist intermediate layer film must be increased in order to achieve reflection of 1% at a film thickness of 250 nm. However, when the film thickness of the resist intermediate layer film is increased in this way, the load on the uppermost resist film during dry etching when processing the resist intermediate layer film is large, which is not preferable.

  FIGS. 5 and 6 show reflections in the case of dry exposure in which the NA of the exposure apparatus lens is 0.85, but the n, k values and film thickness of the resist interlayer film for the three-layer process should be optimized. Thus, it is shown that the reflectance can be 1% or less regardless of the k value of the resist underlayer film. However, the NA of the projection lens exceeds 1.0 due to immersion lithography, and the angle of light incident not only on the resist but also on the antireflection film under the resist is becoming shallower. The antireflection film suppresses reflection not only by the absorption of the film itself but also by the action of cancellation due to the light interference effect. Since oblique light has a small light interference effect, reflection increases. Of the three-layer process film, the resist intermediate layer film is used to prevent reflection by using the interference of light. Since the resist underlayer film is sufficiently thick to use the interference action, there is no antireflection effect due to cancellation by the interference effect. It is necessary to suppress reflection from the surface of the resist underlayer film. For this purpose, the k value of the resist underlayer film must be smaller than 0.6 and the n value must be close to that of the upper resist intermediate film. When the k value is too small and the transparency is too high, reflection from the substrate also occurs. Therefore, in the case of immersion exposure NA 1.3, the optimum k value is about 0.25 to 0.48. The n value is a target value that is close to the n value 1.7 of the resist for both the intermediate layer and the lower layer.

The benzene ring is very strongly absorbed, and the k value of cresol novolac and polyhydroxystyrene exceeds 0.6. One of the higher transparency and higher etching resistance at a wavelength of 193 nm than a benzene ring is a naphthalene ring. For example, Patent Document 8 proposes a resist underlayer film having a naphthalene ring and an anthracene ring. In our measured value, k value of naphthol co-condensed novolak resin and polyvinyl naphthalene resin is between 0.3 and 0.4. In addition, the n value at a wavelength of 193 nm of the naphthol co-condensed novolak resin and the polyvinyl naphthalene resin is low, 1.4 for the naphthol co-condensed novolak resin, and 1.2 for the polyvinyl naphthalene resin. For example, in the acenaphthylene polymers shown in Patent Document 9 and Patent Document 10, the n value at 193 nm is 1.5 and the k value is 0.4, which is close to the target value. There is a need for a lower layer film that has a high n value, a low k value, is transparent, and has high etching resistance.
Here, Patent Document 11 proposes a resist underlayer film forming material having a bisnaphthol group, which has a feature that both n value and k value are close to target values and excellent in etching resistance.

  Further, when there is a step in the substrate to be processed, it is necessary to flatten the step with a resist underlayer film. By flattening the resist lower layer film, it is possible to suppress the film thickness variation of the resist intermediate layer film formed on the resist film and the photoresist film as the resist upper layer film, and to expand the lithography focus margin.

  However, it is difficult for the amorphous carbon underlayer film formed by CVD using methane gas, ethane gas, acetylene gas or the like as a raw material to bury the step flatly. On the other hand, when the resist underlayer film is formed by spin coating, there is an advantage that the unevenness of the substrate can be embedded. Furthermore, in order to improve the embedding characteristics in the coating type material, as shown in Patent Document 12, a method using a novolak having a low molecular weight and a wide molecular weight distribution, as shown in Patent Document 13, a base polymer is used. A method of blending a low molecular compound having a low melting point has been proposed.

It has been well known that novolak resins are crosslinked and cured by heating alone (Non-Patent Document 6). Here, a crosslinking mechanism by radical coupling in which a phenoxy radical is generated in a hydroxy group of a cresol novolac by heating, a radical moves to methylene of a linking group of a novolak resin by resonance, and the methylenes are cross-linked is reported. Patent Document 14 reports a pattern formation method using a lower layer film in which a polycyclic aromatic compound such as polyarylene, naphthol novolak, hydroxyanthracene novolak or the like is dehydrogenated or dehydrated by heat to increase the carbon density.
A glassy carbon film is formed by heating at 800 ° C. or higher (Non-patent Document 7). However, considering the influence on device damage and wafer deformation, the upper limit of the heatable temperature in the lithography wafer process is 600 ° C. or less, preferably 500 ° C. or less.

  It has been reported that with the reduction of the processing line width, a phenomenon that the resist underlayer film is twisted or bent when the substrate to be processed is etched using the resist underlayer film as a mask (Non-patent Document 8). It shows a phenomenon in which hydrogen atoms in a resist underlayer film are replaced with fluorine atoms during substrate etching with a fluorocarbon-based gas. It is considered that the resist underlayer film surface is made Teflon (registered trademark) to swell due to the increase in volume of the underlayer film or the glass transition point is lowered, thereby causing a finer pattern distortion. In the above-mentioned document, it has been shown that twisting can be prevented by applying a resist underlayer film having a low hydrogen content. An amorphous carbon film prepared by CVD can extremely reduce the number of hydrogen atoms in the film, and is very effective in preventing dripping. However, as described above, CVD has poor step embedding characteristics and may be difficult to introduce due to the cost of the CVD apparatus and the occupation footprint area. If the problem can be solved with a coating, particularly a lower layer film material that can be formed by a spin coating method, the merit of simplifying the process and the apparatus is great.

  A multi-layer process in which a hard mask is formed on a resist underlayer film by a CVD method has been studied. In the case of silicon hard masks (silicon oxide film, silicon nitride film, silicon oxynitride film), the etching resistance of inorganic hard masks formed by CVD or the like is higher than that of hard masks formed by spin coating. . Further, the substrate to be processed is a low dielectric constant film, and the photoresist may be contaminated (poisoning) from there, but the CVD film is more effective as a blocking film for preventing poisoning.

  Therefore, a process of forming a resist underlayer film by spin coating for planarization and forming an inorganic hard mask intermediate layer film as a resist intermediate layer film thereon by a CVD method has been studied. When the inorganic hard mask intermediate layer is formed by the CVD method, it is necessary to heat the substrate at a minimum of 300 ° C., usually 400 ° C., particularly in forming a nitride film. Therefore, when a resist underlayer film is formed by spin coating, heat resistance of 400 ° C. is necessary, but ordinary cresol novolak, naphthol novolak, and fluorene bisphenol having high heat resistance can withstand heating at 400 ° C. It cannot be done, and a large film loss occurs after heating. Thus, there is a need for a resist underlayer film that can withstand high-temperature heating when forming an inorganic hard mask intermediate film by CVD.

  Further, due to the problem of film loss after heating and deterioration of the resin due to such heat resistance, conventional heat treatment of the resist underlayer film material is usually performed at 300 ° C. or less (preferably in the range of 80 to 300 ° C.). It was. However, there still remains a problem that the film is reduced after the solvent treatment or the pattern is distorted during the etching of the substrate.

  As described above, it has optimum n and k values and embedding characteristics as an antireflection film, excellent etching resistance and solvent resistance, and can withstand high temperatures during the formation of an inorganic hard mask intermediate film by CVD or the like. There is a need for a method for forming a resist underlayer film that has heat resistance and does not sag during etching of the substrate.

JP-A-6-118651 Japanese Patent Laid-Open No. 10-324748 JP-A-11-302382 JP 2002-55456 A JP-A-9-110938 US Pat. No. 6,506,497 US Pat. No. 6420088 JP 2002-14474 A JP 2001-40293 A JP 2002-214777 A JP 2007-199653 A JP 2002-47430 A JP-A-11-154638 Patent 3504247

SPIE vol. 1925 (1993) p377 SPIE vol. 3333 (1998) p62 J. et al. Photopolymer Sci. and Technol. Vol. 9 No. 3 (1996) p435-446 SPIE vol. 4345 (2001) p50 J. et al. Vac. Sci. Technol. , 16 (6), Nov. / Dec. 1979 SPIE Vol. 469 p72 (1984) Glass Carbon Bull. Chem. Soc. JPN. 41 (12) 3023-3024 (1968) (Proc. Of Symp. Dry. Process, (2005) p11)

  The present invention has been made in view of the above circumstances, and is a method for forming a resist underlayer film of a multilayer resist film having at least three layers used in lithography, which can reduce reflectance, has high etching resistance, and has high heat resistance. Another object of the present invention is to provide a resist underlayer film forming method for forming a resist underlayer film that has solvent resistance and in particular is free from occurrence during etching of a substrate, and a pattern forming method using the resist underlayer film forming method.

（上記一般式（Ａ−１）〜（Ｅ−１）中、Ｒ^１〜Ｒ^４は、同一又は異種の水素原子、炭素数１〜１０の直鎖状、分岐状、環状のアルキル基、炭素数６〜１０のアリール基、炭素数２〜１０のアルケニル基であり、Ｒ^５〜Ｒ^８はそれぞれ水素原子、炭素数１〜６の直鎖状、分岐状、環状のアルキル基、アシル基、あるいはグリシジル基、Ｒ^９は水素原子、炭素数１〜１０の直鎖状、分岐状、環状のアルキル基、アルコキシ基、炭素数２〜１０のアルケニル基、炭素数６〜１０のアリール基、ハロゲン原子、アミノ基、炭素数１〜４のアルキルメチルアミノ基、炭素数６〜１０のジアリールアミノ基、シアノ基、ニトロ基、ｍ、ｎ、ｐ、ｑ、ｒは１〜６の整数である。） In order to solve the above problems, according to the present invention, there is provided a method for forming a resist underlayer film of a multilayer resist film having at least three layers used in lithography, which comprises the following general formulas (A-1) to (E-1): And a resist underlayer film material containing at least one compound selected from the group consisting of a compound having a bisnaphthol group is coated on the substrate, and the coated resist underlayer film material is heated to a temperature exceeding 300 ° C. and not exceeding 600 ° C. Provided is a method for forming a resist underlayer film, characterized in that the resist underlayer film is cured by heat treatment in a range of seconds to 600 seconds.

(In the general formulas (A-1) to (E-1), R ^{1 to} R ⁴ are the same or different hydrogen atoms, linear, branched or cyclic alkyl groups having 1 to 10 carbon atoms, carbon An aryl group having 6 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, and R ^{5 to} R ⁸ are each a hydrogen atom, a linear, branched or cyclic alkyl group having 1 to 6 carbon atoms, an acyl group, Alternatively, a glycidyl group, R ⁹ is a hydrogen atom, a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms, an alkoxy group, an alkenyl group having 2 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, halogen An atom, an amino group, an alkylmethylamino group having 1 to 4 carbon atoms, a diarylamino group having 6 to 10 carbon atoms, a cyano group, a nitro group, m, n, p, q, and r are integers of 1 to 6. )

  One kind of bisnaphthol compound obtained by reacting the carbonyl group of anthanthrone, dibenzpyrenequinone, pyranthrone, violanthrone, or isoviolanthrone with naphthol, as in the above general formulas (A-1) to (E-1) Anti-reflection by coating the resist underlayer film material including the above on the substrate and curing the coated resist underlayer film material at a temperature exceeding 300 ° C. and not exceeding 600 ° C. for 10 seconds to 600 seconds. Optimum n, k value and embedding characteristics as a film, excellent etching resistance, high heat resistance, solvent resistance, can suppress outgassing during baking, especially collapse and twist during substrate etching A resist underlayer film can be formed.

（上記一般式（Ａ−２）〜（Ｅ−２）中、Ｒ^１〜Ｒ^４は、同一又は異種の水素原子、炭素数１〜１０の直鎖状、分岐状、環状のアルキル基、炭素数６〜１０のアリール基、炭素数２〜１０のアルケニル基であり、Ｒ^５〜Ｒ^８はそれぞれ水素原子、炭素数１〜６の直鎖状、分岐状、環状のアルキル基、アシル基、あるいはグリシジル基、Ｒ^９は水素原子、炭素数１〜１０の直鎖状、分岐状、環状のアルキル基、アルコキシ基、炭素数２〜１０のアルケニル基、炭素数６〜１０のアリール基、ハロゲン原子、アミノ基、炭素数１〜４のアルキルメチルアミノ基、炭素数６〜１０のジアリールアミノ基、シアノ基、ニトロ基、Ｒ^１０、Ｒ^１１は炭素数１〜１０の直鎖状、分岐状のアルキレン基であり、ｍ、ｎ、ｐ、ｑ、ｒは１〜６の整数である。） Moreover, it is a formation method of the resist underlayer film of the multilayer resist film which has at least 3 layers used by lithography, Comprising: 1 or more types selected from the following general formula (A-2)-(E-2), Bisnaphthol group The substrate is coated with a resist underlayer film material containing a resin in which a compound having a novolac is formed, and the coated resist underlayer film material is heated to a temperature exceeding 300 ° C. and not more than 600 ° C. for 10 seconds to 600 seconds. Provided is a method for forming a resist underlayer film characterized by being cured by heat treatment.

(In the general formulas (A-2) to (E-2), R ^{1 to} R ⁴ are the same or different hydrogen atoms, linear, branched or cyclic alkyl groups having 1 to 10 carbon atoms, carbon An aryl group having 6 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, and R ^{5 to} R ⁸ are each a hydrogen atom, a linear, branched or cyclic alkyl group having 1 to 6 carbon atoms, an acyl group, Alternatively, a glycidyl group, R ⁹ is a hydrogen atom, a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms, an alkoxy group, an alkenyl group having 2 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, halogen Atom, amino group, alkylmethylamino group having 1 to 4 carbon atoms, diarylamino group having 6 to 10 carbon atoms, cyano group, nitro group, R ¹⁰ and R ¹¹ are linear or branched having 1 to 10 carbon atoms M, n, p, q, r are integers of 1-6 )

  A bisnaphthol compound obtained by reacting a carbonyl group of anthanthrone, dibenzpyrenequinone, pyranthrone, violanthrone, or isoviolanthrone with naphthol, such as the above general formulas (A-2) to (E-2), is a novolak. The substrate is coated with a resist underlayer film material containing at least one resin, and the coated resist underlayer film material is heat-treated at a temperature exceeding 300 ° C. and not exceeding 600 ° C. for 10 seconds to 600 seconds, and cured. Therefore, it has optimal n, k value, embedding characteristics, excellent etching resistance, high heat resistance, and solvent resistance as an antireflection film, and suppresses the generation of outgas during baking, especially during substrate etching. A resist underlayer film that does not collapse or twist can be formed.

The resist underlayer film material is preferably coated on the substrate by spin coating.
Thus, a spin coat method is mentioned as a method of coating the said resist underlayer film material on a board | substrate. When the resist underlayer film is formed by spin coating, the unevenness of the substrate can be embedded.

Moreover, it is preferable that the resist underlayer film material further contains an organic solvent. Moreover, it is preferable that the resist underlayer film material further contains a crosslinking agent and an acid generator.
Thus, it is preferable that the resist underlayer film material further contains an organic solvent. Further, in order to improve spin coating characteristics, step board embedding characteristics, film rigidity and solvent resistance, a crosslinking agent and an acid generator. It is preferable to contain.

  Also, a method of forming a pattern on a substrate by lithography, wherein at least a resist underlayer film is formed on the substrate by the underlayer film forming method, and a resist intermediate layer film material containing silicon atoms on the resist underlayer film A resist intermediate layer film is formed using a resist upper layer film material made of a photoresist composition on the resist intermediate layer film, and a pattern circuit region of the resist upper layer film is exposed. And then developing with a developing solution to form a resist pattern on the resist upper layer film, etching the resist intermediate layer film using the obtained resist pattern as an etching mask, and etching the resist intermediate layer film pattern obtained The resist underlayer film is etched, and the resulting resist underlayer film pattern is used as an etching mask. The substrate is etched Te provides a pattern forming method and forming a pattern on a substrate.

  With such a pattern formation method using the three-layer resist method, a fine pattern can be formed on the substrate with high accuracy.

  A method of forming a pattern on a substrate by lithography, wherein at least a resist underlayer film is formed on the substrate by the resist underlayer film forming method, and a silicon oxide film, a silicon nitride film, and silicon are formed on the resist underlayer film An inorganic hard mask intermediate film selected from oxynitride films is formed, a resist upper film is formed on the inorganic hard mask intermediate film using a resist upper film material made of a photoresist composition, and the resist upper layer is formed. After exposing the pattern circuit area of the film, developing with a developing solution to form a resist pattern on the resist upper layer film, and etching the inorganic hard mask intermediate layer film using the obtained resist pattern as an etching mask Etching the resist underlayer using the inorganic hard mask intermediate layer film pattern as an etching mask. Resist underlayer film pattern by etching the substrate with an etching mask to provide a pattern forming method comprising forming a pattern on substrate.

  Thus, when forming an inorganic hard mask as a resist intermediate film on a resist underlayer film, the resist underlayer film forming method of the present invention can be used to withstand high temperatures during the formation of the inorganic hard mask intermediate film. A resist underlayer film having a property can be formed.

A method of forming a pattern on a substrate by lithography, wherein at least a resist underlayer film is formed on the substrate by the resist underlayer film forming method, and a silicon oxide film, a silicon nitride film, and silicon are formed on the resist underlayer film An inorganic hard mask intermediate layer film selected from oxynitride films is formed, an organic antireflection film is formed on the inorganic hard mask intermediate film, and a resist upper layer made of a photoresist composition is formed on the organic antireflection film After forming a resist upper layer film using a film material, exposing a pattern circuit region of the resist upper layer film, developing with a developing solution to form a resist pattern on the resist upper layer film, and etching the obtained resist pattern Etching the organic antireflection film and the inorganic hard mask interlayer film as a mask, and obtaining the inorganic hard mask interlayer film pattern obtained And the on to the etching mask to etch the resist underlayer film, the resulting resist underlayer film pattern by etching the substrate with an etching mask to provide a pattern forming method comprising forming a pattern on a substrate.
Thus, an organic antireflection film can be formed between the inorganic hard mask intermediate film and the resist upper layer film.

The inorganic hard mask intermediate film is preferably formed by a CVD method or an ALD method.
As described above, the etching resistance can be increased by forming the inorganic hard mask intermediate film by the CVD method or the ALD method.

In addition, the resist upper layer film material does not contain a silicon atom-containing polymer, and the resist lower layer film is etched using the resist intermediate layer film as a mask, using an etching gas mainly composed of oxygen gas or hydrogen gas. Is preferred.
As described above, when the resist underlayer film is etched using the inorganic hard mask intermediate film pattern as an etching mask, an inorganic hard mask containing silicon atoms is preferable in order to exhibit etching resistance by oxygen gas or hydrogen gas.

  As described above, by using the resist underlayer film forming method of a multilayer resist film having at least three layers according to the present invention, it has optimum n and k values and embedding characteristics as an antireflection film, and excellent etching resistance. It is possible to form a resist underlayer film that has high heat resistance and solvent resistance, can suppress outgassing during baking, and does not cause sag during etching of a substrate in a high aspect line narrower than 60 nm. It becomes. Furthermore, when forming an inorganic hard mask on the resist underlayer film formed by using the spin coating method of the present invention by CVD, it has high heat resistance that can withstand high-temperature processing during the formation of the inorganic hard mask intermediate film Therefore, it is possible to provide a pattern forming method in which a resist underlayer film obtained by a spin coating method and an inorganic hard mask obtained by a CVD method are combined.

It is explanatory drawing of a 3 layer process. It is a graph which shows the relationship between the film thickness of the lower layer film | membrane which changed the n value in the range of 1.0-2.0, and the board | substrate reflectance with the lower layer film refractive index k value in 0.3 layer being fixed. It is a graph which shows the relationship between the film thickness of the lower layer film | membrane which changed the k value in the range of 0-0.8, and the board | substrate reflectance with the lower layer film refractive index n value in 2 layer process having fixed 1.5. In the three-layer process, the lower layer refractive index n value is 1.5, the k value is 0.6, the film thickness is fixed to 500 nm, the n value of the intermediate layer is 1.5, the k value is 0 to 0.3, and the film thickness is It is a graph which shows the relationship of a board | substrate reflectance when it changes in the range of 0-400 nm. In the three-layer process, the refractive index n value of the lower layer film is 1.5, the k value is 0.2, the n value of the intermediate layer is 1.5, and the k value is fixed at 0.1 to change the film thickness of the lower layer and the intermediate layer. It is a graph which shows the relationship of the board | substrate reflectance at the time. In the three-layer process, the refractive index n value of the lower layer film is 1.5, the k value is 0.6, the n value of the intermediate layer is 1.5, and the k value is fixed at 0.1 to change the film thickness of the lower layer and the intermediate layer. It is a graph which shows the relationship of the board | substrate reflectance at the time.

Hereinafter, the present invention will be described more specifically.
As described above, as a method for forming a resist underlayer film of a multilayer resist film having at least three layers, it has an excellent antireflection film function and etching resistance, heat resistance, solvent resistance, and embedding characteristics, particularly during etching of a substrate. There has been a need for a method for forming a resist underlayer film that does not sag.

  Conventionally, anthanthrone, dibenzpyrenequinone, pyranthrone, violanthrone, and isoviolanthrone have a function as a photoconductive substance, and in recent years, application as an organic phosphor has been studied (Japanese Patent Laid-Open No. 7-90258). )

  As a result of intensive studies to achieve the above object, the present inventor has found that anthanthrone, dibenzpyrenequinone, pyranthrone, violanthrone, and isoviolane represented by the following general formulas (A-1) to (E-1): A compound having a bisnaphthol group obtained by reacting a carbonyl group of throne with naphthol, and anthanthrone, dibenzpyrenequinone, pyranthrone, violanthrone represented by the following general formulas (A-2) to (E-2), A resin obtained by reacting the carbonyl group of isoviolanthrone with naphthol and having novolak formed from a compound having a bisnaphthol group has been found to have very high heat resistance, and is thermally decomposed when baked at a high temperature exceeding 300 ° C. It has the property of evaporating the solvent without causing it, has high transparency, has excellent etching resistance, especially Excellent accordance prevention effect after a fine pattern etching, was found to be a promising material as a resist lower layer film.

That is, as a resist underlayer film material used in the method for forming a resist underlayer film for a three-layer process of the present invention, a high energy ray having a wavelength of 300 nm or less, specifically, an excimer laser of 248 nm, 193 nm, 157 nm, a soft X of 3-20 nm Excellent etching resistance in X-ray, electron beam, X-ray, high transparency,
(A) Bisnaphthol obtained by reacting a carbonyl group of anthanthrone, dibenzpyrenequinone, pyranthrone, violanthrone, or isoviolanthrone represented by the following general formulas (A-1) to (E-1) with naphthol A novolak resin obtained by novolacizing a compound having a group or a compound having a bisnaphthol group represented by the following general formulas (A-2) to (E-2),
(B) an organic solvent,
(C) base polymer (D) cross-linking agent, in order to increase spin coating characteristics, step board embedding characteristics, film rigidity and solvent resistance,
(E) An acid generator may be added.

（上記一般式（Ａ−１）〜（Ｅ−１）中、Ｒ^１〜Ｒ^４は、同一又は異種の水素原子、炭素数１〜１０の直鎖状、分岐状、環状のアルキル基、炭素数６〜１０のアリール基、炭素数２〜１０のアルケニル基であり、Ｒ^５〜Ｒ^８はそれぞれ水素原子、炭素数１〜６の直鎖状、分岐状、環状のアルキル基、アシル基、あるいはグリシジル基、Ｒ^９は水素原子、炭素数１〜１０の直鎖状、分岐状、環状のアルキル基、アルコキシ基、炭素数２〜１０のアルケニル基、炭素数６〜１０のアリール基、ハロゲン原子、アミノ基、炭素数１〜４のアルキルメチルアミノ基、炭素数６〜１０のジアリールアミノ基、シアノ基、ニトロ基、ｍ、ｎ、ｐ、ｑ、ｒは１〜６の整数である。）

(In the general formulas (A-1) to (E-1), R ^{1 to} R ⁴ are the same or different hydrogen atoms, linear, branched or cyclic alkyl groups having 1 to 10 carbon atoms, carbon An aryl group having 6 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, and R ^{5 to} R ⁸ are each a hydrogen atom, a linear, branched or cyclic alkyl group having 1 to 6 carbon atoms, an acyl group, Alternatively, a glycidyl group, R ⁹ is a hydrogen atom, a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms, an alkoxy group, an alkenyl group having 2 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, halogen An atom, an amino group, an alkylmethylamino group having 1 to 4 carbon atoms, a diarylamino group having 6 to 10 carbon atoms, a cyano group, a nitro group, m, n, p, q, and r are integers of 1 to 6. )

（上記一般式（Ａ−２）〜（Ｅ−２）中、Ｒ^１〜Ｒ^４は、同一又は異種の水素原子、炭素数１〜１０の直鎖状、分岐状、環状のアルキル基、炭素数６〜１０のアリール基、炭素数２〜１０のアルケニル基であり、Ｒ^５〜Ｒ^８はそれぞれ水素原子、炭素数１〜６の直鎖状、分岐状、環状のアルキル基、アシル基、あるいはグリシジル基、Ｒ^９は水素原子、炭素数１〜１０の直鎖状、分岐状、環状のアルキル基、アルコキシ基、炭素数２〜１０のアルケニル基、炭素数６〜１０のアリール基、ハロゲン原子、アミノ基、炭素数１〜４のアルキルメチルアミノ基、炭素数６〜１０のジアリールアミノ基、シアノ基、ニトロ基、Ｒ^１０、Ｒ^１１は炭素数１〜１０の直鎖状、分岐状のアルキレン基であり、ｍ、ｎ、ｐ、ｑ、ｒは１〜６の整数である。）

(In the general formulas (A-2) to (E-2), R ^{1 to} R ⁴ are the same or different hydrogen atoms, linear, branched or cyclic alkyl groups having 1 to 10 carbon atoms, carbon An aryl group having 6 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, and R ^{5 to} R ⁸ are each a hydrogen atom, a linear, branched or cyclic alkyl group having 1 to 6 carbon atoms, an acyl group, Alternatively, a glycidyl group, R ⁹ is a hydrogen atom, a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms, an alkoxy group, an alkenyl group having 2 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, halogen Atom, amino group, alkylmethylamino group having 1 to 4 carbon atoms, diarylamino group having 6 to 10 carbon atoms, cyano group, nitro group, R ¹⁰ and R ¹¹ are linear or branched having 1 to 10 carbon atoms M, n, p, q, r are integers of 1-6 )

The bisnaphthol compound obtained by reacting the carbonyl group of anthanthrone, dibenzpyrenequinone, pyranthrone, violanthrone, or isoviolanthrone with naphthol has a quaternary carbon and has a high carbon ratio of around 90%. Therefore, it has very high heat resistance. When a hard mask such as a silicon oxide film, a silicon nitride film, or a silicon oxynitride film is formed on the resist underlayer film by a CVD method or the like, a high temperature of 300 ° C. or higher is necessary particularly in a nitride film, High heat resistance is also required for the resist underlayer film. In addition, the bisnaphthol compound obtained by reacting the carbonyl group of anthanthrone, dibenzpyrenequinone, pyranthrone, violanthrone, or isoviolanthrone with naphthol is a condensed hydrocarbon of a benzene ring. The absorption is relatively small, and when the three-layer process is used, a good antireflection effect is expected particularly with a film thickness of 100 nm or more. In addition, bisnaphthol compounds such as anthrone, dibenzpyrenequinone, pyranthrone, violanthrone, and isoviolanthrone are CF ₄ / CHF ₃ gas and Cl ₂ / BCl used for substrate processing rather than ordinary m-cresol novolac resin. _The etching resistance to the _3- system gas etching is high, and the hydrogen atoms are reduced by the increase in the number of aromatics, so that the etching resistance, particularly the occurrence of pattern distortion during etching can be suppressed. Further, by baking at a temperature exceeding 300 ° C., it has higher etching resistance and solvent resistance, and can suppress the occurrence of pattern distortion during substrate etching.

Specific examples of the compound having a bisnaphthol group represented by general formulas (A-1) to (E-1) are given below.

Japanese Patent Application Laid-Open No. 2007-99741 discloses a method of synthesizing a compound having a bisnaphthol group by reacting a compound having a carbonyl group with naphthol. Here, a method of synthesizing fluorene bisnaphthol by reacting fluorenone and naphthol in the presence of an acid catalyst is shown.
A method of synthesizing a compound having a bisnaphthol group represented by (A-1) to (E-1) by reacting a carbonyl group of anthanthrone, dibenzpyrenequinone, pyranthrone, violanthrone, or isoviolanthrone with naphthols A similar method can be applied.
Among the above compounds, bisnaphthol compounds in which R ^{5 to} R ⁸ are H can be obtained by reacting naphthol and the corresponding anthanthrone, dibenzpyrenequinone, pyrantrone, violanthrone, or isoviolanthrone according to a conventional method. , R ^{5 to} R ⁸ having a glycidyl group can be obtained by glycidylating the hydroxyl group of the bisnaphthol compound obtained by the above method according to a conventional method.

  Examples of naphthols include 1-naphthol, 2-naphthol, 2-methyl-1-naphthol, 4-methoxy-1-naphthol, 7-methoxy-2-naphthol, 1,5-dihydroxynaphthalene, and 1,7-dihydroxynaphthalene. 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene and the like dihydroxynaphthalene, 1,2,4-trihydroxynaphthalene, 1,3,8-trihydroxynaphthalene and the like. These naphthols may be used alone or in combination of two or more.

In the resist underlayer film forming method of the present invention, as a component (A) of the resist underlayer film material, a compound having a bisnaphthol group as shown by (A-2) to (E-2) is used with an aldehyde. A resin novolakized by a condensation reaction can also be used.
Examples of aldehydes used here include formaldehyde, trioxane, paraformaldehyde, benzaldehyde, acetaldehyde, propylaldehyde, phenylacetaldehyde, α-phenylpropylaldehyde, β-phenylpropylaldehyde, o-hydroxybenzaldehyde, m-hydroxybenzaldehyde, p. -Hydroxybenzaldehyde, o-chlorobenzaldehyde, m-chlorobenzaldehyde, p-chlorobenzaldehyde, o-nitrobenzaldehyde, m-nitrobenzaldehyde, p-nitrobenzaldehyde, o-methylbenzaldehyde, m-methylbenzaldehyde, p-methylbenzaldehyde, p -Ethylbenzaldehyde, pn-butylbenzaldehyde, 1-naphthalde And hydride, 2-naphthalaldehyde, furfural and the like. Of these, formaldehyde can be particularly preferably used.
These aldehydes can be used alone or in combination of two or more.
0.2-5 mol is preferable with respect to 1 mol of bisnaphthol compounds, and, as for the usage-amount of the said aldehyde, More preferably, it is 0.5-2 mol.

A catalyst can also be used for the condensation reaction of bisnaphthols and aldehydes. Specific examples include acidic catalysts such as hydrochloric acid, nitric acid, sulfuric acid, formic acid, oxalic acid, acetic acid, methanesulfonic acid, camphorsulfonic acid, tosylic acid, and trifluoromethanesulfonic acid.
The usage-amount of these acidic catalysts is 1 * 10 < ^-5 > ^-5 * 10 < ^-1 > mol with respect to 1 mol of bisnaphthol compounds. Indene, hydroxyindene, benzofuran, hydroxyanthracene, acenaphthylene, biphenyl, bisphenol, trisphenol, dicyclopentadiene, tetrahydroindene, 4-vinylcyclohexene, norbornadiene, 5-vinylnorborna-2-ene, α-pinene, β-pinene, limonene In the case of a copolymerization reaction with a compound having a non-conjugated double bond such as aldehydes, aldehydes are not necessarily required.

Water, methanol, ethanol, propanol, butanol, tetrahydrofuran, dioxane or a mixed solvent thereof can be used as a reaction solvent in the polycondensation.
These solvents are in the range of 0 to 2,000 parts by mass with respect to 100 parts by mass of the reaction raw material. Although reaction temperature can be suitably selected according to the reactivity of the reaction raw material, it is the range of 10-200 degreeC normally.

As a polycondensation reaction method, there are a method in which a bisnaphthol compound, an aldehyde, and a catalyst are charged together, and a method in which a bisnaphthol compound and an aldehyde are dropped in the presence of a catalyst.
After completion of the polycondensation reaction, in order to remove unreacted raw materials, catalysts, etc. existing in the system, the temperature of the reaction kettle can be raised to 130-230 ° C., and volatile matter can be removed at about 1-50 mmHg. .
The bisnaphthol compounds represented by the general formulas (A-1) to (E-1) may be polymerized alone, but other phenols may be copolymerized.

  The copolymerizable phenols are 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, 2-phenylphenol, 3-phenylphenol, 4-phenylphenol, 3,5-diphenylphenol, 2-naphthylphenol, 3-naphthylphenol, 4-naphthylphenol, 4-tritylphenol, resorcinol, 2-methylresorcinol, 4 -Methylresorcinol 5-methylresorcinol, catechol, 4-t-butylcatechol, 2-methoxyphenol, 3-methoxyphenol, 2-propylphenol, 3-propylphenol, 4-propylphenol, 2-isopropylphenol, 3-isopropylphenol, 4 -Isopropylphenol, 2-methoxy-5-methylphenol, 2-t-butyl-5-methylphenol, pyrogallol, thymol, isothimol and the like can be mentioned.

  In addition, copolymerizable monomers can be copolymerized. Specifically, 1-naphthol, 2-naphthol, 2-methyl-1-naphthol, 4-methoxy-1-naphthol, 7-methoxy-2-naphthol And 1,5-dihydroxynaphthalene, 1,7-dihydroxynaphthalene, dihydroxynaphthalene such as 2,6-dihydroxynaphthalene, methyl 3-hydroxy-naphthalene-2-carboxylate, 4-tritylphenol, indene, hydroxyindene, benzofuran, Hydroxyanthracene, dihydroxyanthracene, trihydroxyanthracene, hydroxypyrene, acenaphthylene, biphenyl, bisphenol, trisphenol, dicyclopentadiene, tetrahydroindene, 4-vinylcyclohexene, norbornadi Emissions, 5 Binirunoruboruna-2-ene, alpha-pinene, beta-pinene, and limonene and the like, it may be a ternary or more copolymer added these things.

  The molecular weight in terms of polystyrene of the novolak resin is preferably a weight average molecular weight (Mw) of 1,000 to 30,000, particularly 2,000 to 20,000. The molecular weight distribution is preferably in the range of 1.2-7, but the crosslinking efficiency is higher when the monomer component, oligomer component or low molecular weight body having a molecular weight (Mw) of 1,000 or less is cut to narrow the molecular weight distribution. In addition, by suppressing the volatile components in the baking, contamination around the baking cup can be prevented.

Next, a condensed aromatic or alicyclic substituent can be introduced into the ortho-position of the hydroxy group of the compound having a bisnaphthol group or a novolak resin thereof.
Specific examples of the substituent that can be introduced here are listed below.

  Of these, polycyclic aromatic groups such as anthracenemethyl group and pyrenemethyl group are most preferably used for 248 nm exposure. In order to improve transparency at 193 nm, those having an alicyclic structure and those having a naphthalene structure are preferably used. On the other hand, since the benzene ring has a window with improved transparency at a wavelength of 157 nm, it is necessary to increase the absorption by shifting the absorption wavelength. The furan ring has a shorter absorption than the benzene ring and slightly improves the absorption at 157 nm, but the effect is small. Naphthalene rings, anthracene rings, and pyrene rings are preferably used because their absorption increases as the absorption wavelength increases, and these aromatic rings also have an effect of improving etching resistance.

Examples of the method for introducing the substituent include a method in which an alcohol in which the substituent is bonded to the hydroxy group is introduced into the polymer after polymerization into the ortho or para position of the hydroxy group of naphthol in the presence of an acid catalyst. It is done. As the acid catalyst, an acidic catalyst such as hydrochloric acid, nitric acid, sulfuric acid, formic acid, oxalic acid, acetic acid, methanesulfonic acid, n-butanesulfonic acid, camphorsulfonic acid, tosylic acid, trifluoromethanesulfonic acid and the like can be used. The usage-amount of these acidic catalysts is 1 * 10 < ^-5 > ^-5 * 10 < ^-1 > mol with respect to 1 mol of phenols. The amount of the substituent introduced is in the range of 0 to 0.8 mol with respect to 1 mol of the hydroxy group of naphthol.

  Transparency at 193 nm of a resin obtained by novolakizing a compound having a bisnaphthol group represented by formulas (A-1) to (E-1) or (A-2) to (E-2) used in the present invention. Hydrogenation can be performed to improve. A preferable hydrogenation ratio is 80 mol% or less, particularly 60 mol% or less of the aromatic group.

Furthermore, it can be blended with other polymers and compounds. As a compound for blending or a polymer for blending, the compound of general formulas (A-1) to (E-1) or the novolak resin of general formulas (A-2) to (E-2) is mixed, It has the role of improving film forming properties and embedding characteristics on a stepped substrate. A material having a high carbon density and high etching resistance is selected.
Such materials 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, 2 -Phenylphenol, 3-phenylphenol, 4-phenylphenol, 3,5-diphenylphenol, 2-naphthylphenol, 3-naphthylphenol, 4-naphthylphenol, 4-tritylphenol, resorcinol, 2-methylresorcinol, 4- Methyl resorcinol, 5-me Luresorcinol, catechol, 4-t-butylcatechol, 2-methoxyphenol, 3-methoxyphenol, 2-propylphenol, 3-propylphenol, 4-propylphenol, 2-isopropylphenol, 3-isopropylphenol, 4-isopropyl Phenol, 2-methoxy-5-methylphenol, 2-t-butyl-5-methylphenol, pyrogallol, thymol, isothymol, 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, 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')-spiro Biindene-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′-dio 1-naphthol, 2-naphthol, 2-methyl-1-naphthol, 4-methoxy-1-naphthol, 7-methoxy-2-naphthol and 1,5-dihydroxynaphthalene, 1,7-dihydroxynaphthalene, 2, Dihydroxynaphthalene such as 1,6-dihydroxynaphthalene, methyl 3-hydroxy-naphthalene-2-carboxylate, indene, hydroxyindene, benzofuran, hydroxyanthracene, acenaphthylene, biphenyl, bisphenol, trisphenol, dicyclopentadiene, tetrahydroindene, 4- Novolac resins such as vinylcyclohexene, norbornadiene, 5-vinylnorborna-2-ene, α-pinene, β-pinene, limonene, polyhydroxystyrene, polystyrene, polyvinylnaphthalene, poly Examples thereof include vinyl anthracene, polyvinyl carbazole, polyindene, polyacenaphthylene, polynorbornene, polycyclodecene, polytetracyclododecene, polynortricyclene, poly (meth) acrylate, and copolymers thereof.

  Further, a nortricyclene copolymer described in JP-A No. 2004-205658, a hydrogenated naphthol novolak resin described in JP-A No. 2004-205676, a naphthol dicyclopentadiene copolymer described in JP-A No. 2004-205665, 2004-354554, and 2005-2005. No. 10431 phenol dicyclopentadiene copolymer, 2005-128509 fluoreneville phenol novolak, 2005-250434 acenaphthylene copolymer, 2006-53543 indene copolymer, 2006-227391 Fullerenes having the phenol group described in the above, Bisphenol compounds described in the same 2006-259249, 2006-293298, 2007-316282 and this novolak resin, 200 -259482 dibisphenol compound and this novolak resin, 2006-285095 adamantane phenol compound novolak resin, 2007-171895 hydroxyvinylnaphthalene copolymer, 2007-199653 bisnaphthol compound and this novolak Resin, ROMP described in JP-A-2008-26600, resin compound shown in tricyclopentadiene copolymer described in JP-A-2008-96684, fullerene resin compound described in JP-A-2006-227391 and 2008-158002 can also be blended.

  The blending amount of the blending compound or blending polymer is 0 to 100 parts by weight of the compound represented by the general formulas (A-1) to (E-1) or (A-2) to (E-2). 1000 parts by weight, preferably 0 to 500 parts by weight.

  In contrast to the novolak resins (A-2) to (E-2) of the resist underlayer film material used in the resist underlayer film forming method of the present invention, the compounds (monomer components) used for condensation (A-1) to (E-) 1) can also be added. The addition of the monomer component has the merit of improving the embedding characteristics without changing the optical constant. The addition amount is 0 to 1000 parts by weight, preferably 0 to 500 parts by weight with respect to 100 parts by weight of the novolak resin, and the addition amount can be appropriately adjusted while observing the embedding characteristics. In the case of a conventional resist underlayer film material, if too much monomer component is added, outgassing may occur during baking and particles may be generated and contaminate the baking furnace. It was necessary to keep the amount added. On the other hand, the compounds (A-1) to (E-1) having a bisnaphthol group used in the resist underlayer film forming method of the present invention have four naphthol groups in the molecule. Since naphthol groups are involved in crosslinking, having many naphthol groups can not only form a lower layer film having high hardness after crosslinking, but also the outgassing hardly occurs due to the rapid crosslinking speed.

  As one of the performance required for the resist underlayer film including the antireflection film function, there is no intermixing between the resist intermediate layer containing silicon and the resist upper layer film formed on the resist underlayer film, and the resist upper layer. It is mentioned that there is no diffusion of low molecular components to the film and the resist intermediate film (Proc. SPIE Vol. 2195, p225-229 (1994)). In order to prevent these problems, a method is generally employed in which thermal crosslinking is performed by baking after spin coating of the antireflection film. Therefore, when a crosslinking agent is added as a component of the antireflection film material, a method of introducing a crosslinkable substituent into the polymer may be employed. Even in the case where a crosslinking agent is not particularly added, in the case of a resin in which a compound having a bisnaphthol group of (A-2) to (E-2) is novolakized, it is crosslinked by a reaction mechanism described later by heating above 300 ° C. It can be made.

  A compound having a bisnaphthol group (A-1) to (E-1) and a compound having a bisnaphthol group (A-2) to (E-2) used in the resist underlayer film forming method of the present invention are novolaks. Since the heat-resistant resin has very high heat resistance, thermal decomposition hardly occurs even if it is baked at a high temperature exceeding 300 ° C. The present inventor further shows that this compound and its novolak resin have properties such that evaporation of a solvent and the like is promoted by high-temperature baking exceeding 300 ° C., and the carbon density and denseness of the film are increased, and etching resistance is improved. I found. Moreover, it discovered that it has high solvent resistance by baking exceeding 300 degreeC, and can generate | occur | produce the twist generate | occur | produced during the etching of a board | substrate. When a material having low heat resistance is baked at a high temperature exceeding 300 ° C., thermal decomposition occurs, so that the carbon density does not always increase, but may deteriorate.

  As the crosslinking agent that can be used in the present invention, materials described in paragraphs (0055) to (0060) of JP-A-2007-199653 can be added.

  In the present invention, an acid generator for further promoting the crosslinking reaction by heat can be added. There are acid generators that generate an acid by thermal decomposition and those that generate an acid by light irradiation, and any of them can be added. Specifically, the materials described in paragraphs (0061) to (0085) of JP-A-2007-199653 can be added.

Furthermore, the resist underlayer film material used in the resist underlayer film forming method of the present invention may contain a basic compound for improving storage stability. As a basic compound, it plays the role of the quencher with respect to an acid in order to prevent the acid which generate | occur | produced in trace amount from the acid generator to advance a crosslinking reaction.
As such a basic compound, specifically, materials described in paragraphs (0086) to (0090) of JP-A-2007-199653 can be added.

  The organic solvent that can be used in the resist underlayer film material used in the resist underlayer film forming method of the present invention is not particularly limited as long as it dissolves the base polymer, acid generator, crosslinking agent, and other additives. . Specifically, the solvents described in paragraphs (0091) to (0092) of JP-A-2007-199653 can be added.

  In order to improve the coating property in the spin coating in the lower layer film forming material used in the pattern forming method of the present invention, a surfactant can be added. As the surfactant, those described in (0165) to (0166) of JP-A-2008-111103 can be used.

  In the resist underlayer film forming method of the present invention, the above resist underlayer film material is coated on a substrate to be processed by a spin coat method or the like in the same manner as a photoresist. Good embedding characteristics can be obtained by using a spin coating method or the like. After spin coating, the solvent is evaporated and baking is performed to promote the crosslinking reaction in order to prevent mixing with the resist upper layer film and resist intermediate layer film. Baking is performed within the range of 300 ° C. or more and 600 ° C. or less, and is performed for 10 to 600 seconds, preferably 10 to 300 seconds. The baking temperature is more preferably 350 ° C. or higher and 500 ° C. or lower. Considering the influence on device damage and wafer deformation, the upper limit of the heatable temperature in the lithography wafer process is 600 ° C. or less, preferably 500 ° C. or less.

  The aforementioned SPIE Vol. 469 p72 (1984), the novolac resin generates a phenoxy radical by heating, and the methylene group of the novolac bond is activated to bond and crosslink the methylene groups. Since this reaction is a radical reaction, no desorbed molecules are generated, so that if the material has high heat resistance, film shrinkage due to crosslinking does not occur.

The atmosphere in the bake may be air, but it is preferable to enclose an inert gas such as N ₂ , Ar, or He in order to reduce oxygen, in order to prevent oxidation of the resist underlayer film. In order to prevent oxidation, it is necessary to control the oxygen concentration, preferably 1000 ppm or less, more preferably 100 ppm or less. It is preferable to prevent oxidation of the resist underlayer film during baking because absorption does not increase and etching resistance does not decrease.

  Although the thickness of the resist underlayer film is appropriately selected, it is preferably 30 to 20,000 nm, particularly 50 to 15,000 nm. After producing the resist underlayer film, in the case of a three-layer process, a resist intermediate layer film containing silicon and a resist upper layer film not containing silicon can be formed thereon.

  The pattern forming method of the present invention is a compound having a bisnaphthol group represented by the general formulas (A-1) to (E-1) or represented by the general formulas (A-2) to (E-2). A resist underlayer film material containing a resin in which a compound having a bisnaphthol group is novolakized is coated on a substrate to form a resist underlayer film, and a photoresist is formed on the resist underlayer film via a resist intermediate layer film. Form a resist upper layer film of the composition, irradiate a desired region of this resist upper layer film with radiation, etc., develop with a developing solution to form a resist pattern, and use the obtained resist pattern as a mask to form a resist intermediate layer film The resist underlayer film and the substrate are processed by etching and using the obtained resist intermediate layer pattern as a mask.

  When an inorganic hard mask intermediate layer film is formed on the resist underlayer film, a silicon oxide film, a silicon nitride film, and a silicon oxynitride film (SiON film) are formed by CVD, ALD, or the like. A method for forming a nitride film is described in Japanese Patent Application Laid-Open No. 2002-334869 and WO 2004/066377. The film thickness of the inorganic hard mask is 5 to 200 nm, preferably 10 to 100 nm. Among them, a SiON film having a high effect as an antireflection film is most preferably used. Since the substrate temperature when forming the SiON film is 300 to 500 ° C., it is necessary to withstand the temperature of 300 to 500 ° C. as the lower layer film. The compounds having general formulas (A-1) to (E-1) and having bisnaphthol groups represented by general formulas (A-1) to (E-1) and compounds having bisnaphthol groups (A-2) to (E-2) used in the present invention were novolakized. Since the resist underlayer film material containing resin has high heat resistance and can withstand high temperatures of 300 ° C. to 500 ° C., an inorganic hard mask formed by a CVD method or an ALD method and a spin coating method are used. Combinations of the formed resist underlayer films are possible.

  A photoresist film may be formed as a resist upper layer film on such a resist intermediate layer film. However, an organic antireflection film (BARC) is formed on the resist intermediate layer film by spin coating, and on that, A photoresist film may be formed. When the SiON film is used as the resist intermediate layer film, reflection can be suppressed even in immersion exposure with a high NA exceeding 1.0 by the two antireflection films of the SiON film and the BARC film. Another advantage of forming the BARC is that it has the effect of reducing the tailing of the photoresist pattern immediately above the SiON.

  A polysilsesquioxane-based intermediate layer is also preferably used as the silicon-containing resist intermediate layer film in the three-layer process. By providing the resist intermediate layer film as an antireflection film, reflection can be suppressed. Specifically, JP-A-2004-310019, 2005-15779, 2005-18054, 2005-352104, 2007-65161, 2007-163846, 2007-226170, 2007- The material containing the silsesquioxane base silicon compound shown to 226204 is mentioned.

  Especially for 193 nm exposure, if a material having many aromatic groups and high substrate etching resistance is used as the resist underlayer film, the k value increases and the substrate reflection increases, but the resist intermediate layer film suppresses reflection. Substrate reflection can be reduced to 0.5% or less.

  As the resist intermediate layer film having an antireflection effect, an anthracene is used for exposure at 248 nm and 157 nm, a light-absorbing group having a phenyl group or a silicon-silicon bond is pendant for exposure at 193 nm, and a polysilsesquide that is crosslinked by acid or heat. Oxane is preferably used.

  The formation of a silicon-containing resist intermediate layer film by spin coating is simpler and more cost effective than CVD.

The resist upper layer film in the three-layer resist film may be either a positive type or a negative type, and the same one as a commonly used photoresist composition can be used. When forming a single layer resist upper layer film with the said photoresist composition, a spin coat method is used preferably similarly to the case where the said resist lower layer film is formed. The photoresist composition is spin-coated and then pre-baked, and the range of 60 to 180 ° C. and 10 to 300 seconds is preferable. Thereafter, exposure is performed according to a conventional method, post-exposure baking (PEB), and development is performed to obtain a resist pattern. The thickness of the resist upper layer film is not particularly limited, but is preferably 30 to 500 nm, particularly 50 to 400 nm.
Examples of the exposure light include high energy rays having a wavelength of 300 nm or less, specifically, excimer lasers of 248 nm, 193 nm, and 157 nm, soft X-rays of 3 to 20 nm, electron beams, and X-rays.

  Next, etching is performed using the obtained resist pattern as a mask. Etching of the resist interlayer film, particularly the inorganic hard mask, in the three-layer process is performed using a resist pattern as a mask using a fluorocarbon gas. Next, the resist underlayer film is etched using oxygen gas or hydrogen gas using the resist intermediate layer film pattern, particularly the inorganic hard mask pattern as a mask.

Etching of the next substrate to be processed can also be performed by a conventional method. For example, if the substrate is SiO ₂ , SiN, silica-based low dielectric constant insulating film, etching mainly using CFC-based gas, p-Si, Al, In W, etching mainly using chlorine and bromine gases is performed. When the substrate processing is etched with chlorofluorocarbon gas, the silicon-containing intermediate layer in the three-layer process is peeled off simultaneously with the substrate processing. When the substrate is etched with a chlorine-based or bromine-based gas, the silicon-containing intermediate layer needs to be separated by dry etching with a chlorofluorocarbon-based gas after the substrate is processed.

The resist underlayer film formed by the resist underlayer film forming method of the present invention is characterized by excellent etching resistance of these substrates to be processed.
Note that as a substrate to be processed, a layer to be processed is formed on the substrate. The substrate is not particularly limited, and a substrate made of a material different from the layer to be processed such as Si, α-Si, p-Si, SiO ₂ , SiN, SiON, W, TiN, Al, or the like is used. The layer to be _{processed, Si, SiO 2, SiON,} SiN, p-Si, α-Si, W, W-Si, Al, Cu, Al-Si , etc. Various Low-k film and stopper film are used Usually, it can be formed to a thickness of 50 to 10,000 nm, particularly 100 to 5,000 nm.

  An example of the three-layer process is specifically shown below with reference to FIG.

  In the case of a three-layer process, as shown in FIG. 1 (A), after forming a resist underlayer film 3 according to the present invention on a work layer 2 laminated on a substrate 1, a resist intermediate layer film 4 is formed. Then, a resist upper layer film 5 is formed thereon.

Next, as shown in FIG. 1B, the desired portion 6 of the resist upper layer film is exposed, and PEB and development are performed to form a resist pattern 5a (FIG. 1C). Using the obtained resist pattern 5a as a mask, the resist intermediate layer film 4 is etched using a CF-based gas to form a resist intermediate layer film pattern 4a (FIG. 1D). After removing the resist pattern 5a, the resist underlayer film 3 is subjected to oxygen plasma etching using the obtained resist intermediate layer film pattern 4a as a mask to form a resist underlayer film pattern 3a (FIG. 1E). Further, after removing the resist intermediate layer film pattern 4a, the layer 2 to be processed is etched using the resist underlayer film pattern 3a as a mask to form the pattern 2a on the substrate (FIG. 1F).
When an inorganic hard mask intermediate film is used, the resist intermediate layer film 4 is an inorganic hard mask intermediate film. When BARC is laid, a BARC layer is provided between the resist intermediate layer film 4 and the resist upper layer film 5. The BARC etching may be performed continuously prior to the etching of the resist intermediate layer film 4 or the resist intermediate layer film 4 may be etched by changing the etching apparatus after performing only the BARC etching. it can.

In addition, the measuring method of molecular weight was specifically performed by the following method.
The polystyrene equivalent weight average molecular weight (Mw) and number average molecular weight (Mn) were determined by gel permeation chromatography (GPC), and the degree of dispersion (Mw / Mn) was determined.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated concretely, this invention is not limited by these description.

(Compound synthesis example) Bisnaphthol A-1 to Bisnaphthol E-1, C-E1
In a 1 L flask, 40.6 g of pyrantrone (8,16-pyrantorangeone), 144 g of 2-naphthol, 4 g of β-mercaptopropionic acid, and 500 g of toluene were mixed, 10 g of 98% sulfuric acid was added dropwise, and the mixture was stirred at 80 ° C. for 10 hours. It reacted by doing. To the obtained reaction solution, 100 g of toluene and 30 g of water were added, and tetramethylammonium hydroxide in a 10% aqueous solution was added until PH became 7, then, the water washing was repeated 5 times, and then the aqueous layer was removed. Bisnaphthol C-1 was obtained. ^The structure was identified by ¹ H-NMR analysis.

Birantol A-1 was obtained by changing the pyrantrone to anthanthrone and performing the same reaction.
A similar reaction was carried out by changing the pyranthrone to dibenzpyrenequinone to obtain bisnaphthol B-1.
Birantol D-1 was obtained by changing the pyrantron to isoviolanthrone and performing the same reaction.
Birantolol E-1 was obtained by changing the pyrantron to violanthrone and performing the same reaction.
Bisnaphthol C-1 was reacted with epichlorohydrin to obtain C-E1.
Bisnaphthol A-1 to E-1 and C-E1 synthesized by the above method are shown below.

(Polymer synthesis example 1) Polymer 1
169 g of bisnaphthol A-1, 75 g of a 37% formalin aqueous solution, 5 g of oxalic acid, and 200 g of dioxane were added to a 1 L flask, and the mixture was stirred at 100 ° C. for 24 hours. After the reaction, it is dissolved in 500 ml of methyl isobutyl ketone, the catalyst and metal impurities are removed by washing with sufficient water, the solvent is removed under reduced pressure, the pressure is reduced to 150 ° C. and 2 mmHg, and the polymer 1 shown below is obtained except for moisture and unreacted monomers. It was.
Molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the ratio in the polymer was determined by ¹ H-NMR analysis as follows.
Polymer 1 Mw 5,500, Mw / Mn 4.90

(Polymer synthesis example 2) Polymer 2
To a 1 L flask, 174 g of bisnaphthol B-1, 75 g of 37% formalin aqueous solution, 5 g of oxalic acid, and 200 g of dioxane were added, and the mixture was stirred at 100 ° C. for 24 hours. After the reaction, it is dissolved in 500 ml of methyl isobutyl ketone, the catalyst and metal impurities are removed by washing with sufficient water, the solvent is removed under reduced pressure, the pressure is reduced to 150 ° C. and 2 mmHg, and water and unreacted monomers are removed to obtain the polymer 2 shown below. It was.
Molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the ratio in the polymer was determined by ¹ H-NMR analysis as follows.
Polymer 2 Mw5,900, Mw / Mn5.3

(Polymer synthesis example 3) Polymer 3
To a 300 ml flask were added 189 g of bisnaphthol C-1, 75 g of a 37% formalin aqueous solution, 5 g of oxalic acid, and 200 g of dioxane, and the mixture was stirred at 100 ° C. for 24 hours. After the reaction, it is dissolved in 500 ml of methyl isobutyl ketone, the catalyst and metal impurities are removed by washing with sufficient water, the solvent is removed under reduced pressure, the pressure is reduced to 150 ° C. and 2 mmHg, and water and unreacted monomers are removed to obtain the polymer 3 shown below. It was.
Molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the ratio in the polymer was determined by ¹ H-NMR analysis as follows.
Polymer 3 Mw 4,900, Mw / Mn 4.80

(Polymer Synthesis Example 4) Polymer 4
200 g of bisnaphthol D-1, 75 g of 37% formalin aqueous solution, 5 g of oxalic acid, and 200 g of dioxane were added to a 300 ml flask, and the mixture was stirred at 100 ° C. for 24 hours with stirring. After the reaction, it is dissolved in 500 ml of methyl isobutyl ketone, the catalyst and metal impurities are removed by washing with sufficient water, the solvent is removed under reduced pressure, the pressure is reduced to 150 ° C. and 2 mmHg, and the polymer 4 shown below is obtained except for moisture and unreacted monomers. It was.
Molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the ratio in the polymer was determined by ¹ H-NMR analysis as follows.
Polymer 4 Mw 6,100, Mw / Mn 5.60

(Polymer synthesis example 5) Polymer 5
200 g of bisnaphthol E-1, 75 g of 37% formalin aqueous solution, 5 g of oxalic acid and 200 g of dioxane were added to a 300 ml flask, and the mixture was stirred at 100 ° C. for 24 hours with stirring. After the reaction, it is dissolved in 500 ml of methyl isobutyl ketone, the catalyst and metal impurities are removed by washing with sufficient water, the solvent is removed under reduced pressure, the pressure is reduced to 150 ° C. and 2 mmHg, and water and unreacted monomers are removed to obtain the polymer 5 shown below. It was.
Molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the ratio in the polymer was determined by ¹ H-NMR analysis as follows.
Polymer 5 Mw 5,200, Mw / Mn 4.67

(Comparative Synthesis Example 1) Comparative polymer 1
200 g of fluorene bisphenol, 75 g of a 37% formalin aqueous solution, and 5 g of oxalic acid were added to a 300 ml flask and stirred at 100 ° C. for 24 hours while stirring. After the reaction, it is dissolved in 500 ml of methyl isobutyl ketone, the catalyst and metal impurities are removed by washing with sufficient water, the solvent is removed under reduced pressure, the pressure is reduced to 150 ° C. and 2 mmHg, moisture and unreacted monomers are removed, and 135 g of the comparison shown below Polymer 1 was obtained.
Molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the ratio in the polymer was determined by ¹ H-NMR analysis as follows.
Comparative polymer 1 Mw 6,500, Mw / Mn 5.20

  Further, as comparative polymer 2, m-cresol novolak resin having Mw of 8,800 and Mw / Mn 4.5 was used, and as comparative polymer 3, polyhydroxystyrene having Mw of 9,200 and Mw / Mn of 1.05 was used.

For Comparative monomer 1 to Comparative monomer 3, the following compounds were used.

(Preparation of resist underlayer film material and resist intermediate layer film material)
As shown in Table 1, bisnaphthol A-1 to E-1, C-E1, polymers 1 to 5, comparative polymers 1 to 3, comparative monomers 1 to 3, polymers for silicon-containing intermediate layers, blend polymers 1 and 2, An acid generator represented by AG1 and a crosslinking agent represented by CR1 were dissolved in a solvent containing 0.1% by mass of FC-4430 (manufactured by Sumitomo 3M Ltd.) at a ratio shown in Table 1, and 0.1 μm A resist underlayer film solution and a resist interlayer film solution were prepared by filtering with a fluororesin filter.

(Refractive index measurement)
The resist underlayer film solution prepared as described above was applied on a silicon substrate, UDL-1 to 16 and Comparative Examples UDL-1 and 4 to 7 were baked at 350 ° C. for 60 seconds, and Comparative Examples UDL-2 and 3 Were baked at 230 ° C. for 60 seconds to form lower layer films each having a thickness of 200 nm. A silicon-containing intermediate layer solution prepared as described above was applied onto a silicon substrate and baked at 200 ° C. for 60 seconds to form a silicon-containing film having a thickness of 35 nm (hereinafter abbreviated as SOG-1). A. The refractive index (n, k) of UDL 1 to 16, comparative examples UDL-1 to 7 and SOG 1 at a wavelength of 193 nm was obtained by a spectroscopic ellipsometer with variable incident angle (VASE) manufactured by Woollam, and the results are shown in Table 1.

ＰＧＭＥＡ；プロピレングリコールモノメチルエーテルアセテート

PGMEA; propylene glycol monomethyl ether acetate

In Table 1, the acid generator indicated by AG1 and the crosslinking agent indicated by CR1 were as follows.

As the blending polymer, the following novolak resin for blending (blend polymer 1) and blend polymer 2 polymerized by radical polymerization were used.

Moreover, the following were used as the ArF silicon-containing intermediate layer polymer.

(Measurement of solvent resistance) Examples 1 to 20 and Comparative Examples 1 to 11
UDL-1 to 16 and Comparative Examples UDL1 to 7 were applied on a silicon substrate, and the film thickness was measured by baking for 60 seconds at a temperature shown in Table 2 below under a nitrogen stream. Dispensing, standing for 30 seconds, spin-drying, baking at 100 ° C. for 60 seconds to evaporate PGMEA, measuring the film thickness, and determining the film thickness difference before and after PGMEA treatment. The results are shown in Table 2.

(Etching test with CF ₄ / CHF ₃ gas)
The above resist underlayer film material is applied on a silicon substrate, UDL-1 to 16 and Comparative Examples UDL-1 and 4 to 7 are baked at 350 ° C. for 60 seconds, and Comparative Examples UDL-2 and 3 are 230 ° C. The film was baked for 60 seconds to form an underlayer film having a thickness of 200 nm, and an etching test with a CF ₄ / CHF ₃ gas was performed under the following conditions. In this case, the difference in film thickness of the polymer film before and after etching was determined using a dry etching apparatus TE-8500 manufactured by Tokyo Electron Limited. The results are shown in Table 3.
Etching conditions are as shown below.
Chamber pressure 40.0Pa
RF power 1,300W
CHF ₃ gas flow rate 30ml / min
CF ₄ gas flow rate 30ml / min
Ar gas flow rate 100ml / min
60 sec

(Pattern Etching Test) Examples 21 to 36, Comparative Examples 12 to 18
A resist underlayer film material (UDL-1 to 16, Comparative Example UDL-1 to 7) is applied on a 300 mm diameter Si wafer substrate on which a 200 nm thick SiO ₂ film is formed, and UDL-1 to 16, Comparative Example UDL-1 and 4-7 were baked at 350 ° C. for 60 seconds to form a resist underlayer film having a thickness of 200 nm. In Comparative Examples UDL-2 and 3, baking was performed at 230 ° C. for 60 seconds to form a resist underlayer film having a thickness of 200 nm. The resist underlayer film was baked in a nitrogen stream.
A silicon-containing resist intermediate layer material SOG-1 is applied thereon, baked at 200 ° C. for 60 seconds to form a resist intermediate layer film having a thickness of 35 nm, and a resist upper layer film material (Ar resist SL resist solution) is applied. The resist upper layer film having a thickness of 100 nm was formed by baking at 105 ° C. for 60 seconds. An immersion protective film (TC-1) was applied to the resist upper layer film and baked at 90 ° C. for 60 seconds to form a protective film having a thickness of 50 nm.

As a resist upper layer film material, a resin, an acid generator, and a base compound having the composition shown in Table 4 are dissolved in a solvent containing 0.1% by mass of FC-4430 (manufactured by Sumitomo 3M Limited), and 0.1 μm It was prepared by filtering with a fluororesin filter.

In Table 4, the following were used for the ArF single layer resist polymer, PAG1, and TMMEA.

The immersion protective film (TC-1) was prepared by dissolving a resin having the composition shown in Table 5 in a solvent and filtering with a 0.1 μm fluororesin filter.

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

  Next, exposure was performed with an ArF immersion exposure apparatus (Nikon Corporation; NSR-S610C, NA 1.30, σ 0.98 / 0.65, 35 ° dipole polarized illumination, 6% halftone phase shift mask), and 100 ° C. Was baked for 60 seconds (PEB) and developed with an aqueous 2.38 mass% tetramethylammonium hydroxide (TMAH) solution for 30 seconds to obtain a 43 nm 1: 1 positive line and space pattern.

Next, processing of silicon-containing resist intermediate layer film (SOG) using the resist pattern by dry etching as a mask using Tokyo Electron etching apparatus Telius, resist underlayer film using the silicon-containing resist intermediate layer film as a mask, and the obtained resist The SiO ₂ film was processed using the lower layer film pattern as a mask. Etching conditions are as shown below.

Transfer conditions of resist pattern to resist interlayer film.
Chamber pressure 10.0Pa
RF power 1,500W
CF ₄ gas flow rate 75sccm
O ₂ gas flow rate 15sccm
Time 15sec

Transfer conditions of resist interlayer film pattern to resist underlayer film.
Chamber pressure 2.0Pa
RF power 500W
Ar gas flow rate 75sccm
O ₂ gas flow rate 45sccm
Time 120sec

Transfer conditions of resist underlayer film pattern to SiO ₂ film.
Chamber pressure 2.0Pa
RF power 2,200W
C ₅ F ₁₂ gas flow rate 20 sccm
C ₂ F ₆ gas flow rate 10 sccm
Ar gas flow rate 300sccm
O ₂ 60 sccm
90 seconds

The cross sections of the patterns were observed with an electron microscope (S-4700) manufactured by Hitachi, Ltd., and the shapes were compared and summarized in Table 6.

(Step Substrate Embedding Characteristics) Examples 37 and 38, Comparative Examples 19-22
UDL-1 and 6 and comparative example UDL adjusted to have a thickness of 200 nm on a flat substrate on a SiO ₂ stepped substrate on which a dense hole pattern having a thickness of 500 nm and a diameter of 160 nm is formed on a Si substrate -4 to 7 were applied and baked at 350 ° C for 60 seconds.
The substrate was cleaved, and it was observed by SEM whether the film was buried up to the bottom of the hole. The results are shown in Table 7.

(Outgas measurement) Examples 39 and 40, Comparative Examples 23 to 26
UDL-1, UDL-6 and Comparative Examples UDL-4 to 7 are coated on a Si substrate, baked at 350 ° C. for 60 seconds, and under the condition that a 200 nm-thick underlayer film can be formed, a hot plate is baked at 350 ° C. The number of particles having a size of 0.3 microns and 0.5 microns was measured for particles generated in the oven using a particle counter KR-11A manufactured by Lion. The results are shown in Table 8.

As shown in Table 1, the resist underlayer film formed by the resist underlayer film forming method of the present invention has a refractive index suitable for practical use as a resist underlayer film in a three-layer process for immersion lithography.
As shown in Table 2, when formed by baking at a temperature exceeding 300 ° C. as in the present invention, a resist underlayer film insoluble in the solvent was formed (Examples 1 to 20). On the other hand, when the resist film material UDL-1 was baked at a temperature of 300 ° C. or lower to form a resist underlayer film, a resist underlayer film having a low solvent resistance was formed by dissolution in a solvent by 10% or more by solvent treatment (Comparative Example 1). ~ 3). In addition, the compounds having the bisnaphthol group represented by the general formulas (A-1) to (E-1) and the compounds having the bisnaphthol group represented by (A-2) to (E-2) were novolakized. When a compound (monomer) or resin other than the resin was used, a film thickness larger than that of the example was generated (Comparative Examples 4, 5, 7 to 10).
As shown in Table 3, the rate of CF ₄ / CHF ₃ gas etching of the resist underlayer film formed by the method of the present invention was as follows: Comparative polymer 1 having no bisnaphthol group (Comparative Example UDL-1), m-cresol Novolak resin (Comparative Example UDL-2), polyhydroxystyrene (Comparative Example UDL-3), a compound having a bisnaphthol group represented by the above general formulas (A-1) to (E-1), and the above general formula (A -2) to (E-2) When the compound or resin other than the resin in which the compound having a bisnaphthol group represented by (E-2) is novolakized is used (Comparative Example UDL-4 to 7), the etching rate is very low. High etching resistance.
As shown in Table 6, the resist underlayer film formed by the method of the present invention has a good resist shape after development, the shape of the underlayer film after oxygen etching and substrate processing etching, and the occurrence of pattern distortion is also seen. (Examples 21 to 36). On the other hand, the compounds having bisnaphthol groups represented by the general formulas (A-1) to (E-1) and the compounds having bisnaphthol groups represented by (A-2) to (E-2) were novolakized. When a compound or resin other than the resin is used, the shape after the substrate processing etching becomes a taper shape, the film thickness is reduced, or the pattern is distorted (Comparative Examples 12 to 14, Comparative Example 17, 18).
As shown in Table 7, in Comparative Example 19, defective filling was found. On the other hand, the embedding property was further improved by adding a monomer (compound) to the resist underlayer film material. However, when a monomer is added, as shown in Comparative Examples 24-26 in Table 8, particles are generated during baking, and the oven of the hot plate is contaminated. The resist underlayer film formed using the resist underlayer film material containing the bisnaphthol compound of the present invention does not generate particles even when many low molecules such as monomers are added, and has both embedding characteristics and particle prevention characteristics. Can be achieved at the same time.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has any configuration that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits the same effects. It is contained in the technical range.

DESCRIPTION OF SYMBOLS 1 ... Board | substrate, 2 ... Processed layer, 3 ... Resist underlayer film, 4 ... Resist intermediate layer film, 5 ... Resist upper layer film, 6 ... Exposed part, 5a ... Resist pattern, 4a ... Resist intermediate layer film pattern, 3a ... Resist Lower layer film pattern, 2a: pattern formed on the substrate.

Claims (10)

A method for forming a resist underlayer film of a multilayer resist film having at least three layers used in lithography, having one or more bisnaphthol groups selected from the following general formulas (A-1) to (E-1) Coating a resist underlayer film material containing a compound on a substrate, and curing the coated resist underlayer film material by heat-treating at a temperature exceeding 300 ° C. and not exceeding 600 ° C. for 10 seconds to 600 seconds; A resist underlayer film forming method.

(In the general formulas (A-1) to (E-1), R ^{1 to} R ⁴ are the same or different hydrogen atoms, linear, branched or cyclic alkyl groups having 1 to 10 carbon atoms, carbon An aryl group having 6 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, and R ^{5 to} R ⁸ are each a hydrogen atom, a linear, branched or cyclic alkyl group having 1 to 6 carbon atoms, an acyl group, Alternatively, a glycidyl group, R ⁹ is a hydrogen atom, a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms, an alkoxy group, an alkenyl group having 2 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, halogen An atom, an amino group, an alkylmethylamino group having 1 to 4 carbon atoms, a diarylamino group having 6 to 10 carbon atoms, a cyano group, a nitro group, m, n, p, q, and r are integers of 1 to 6. ) A method for forming a resist underlayer film of a multilayer resist film having at least three layers used in lithography, having one or more bisnaphthol groups selected from the following general formulas (A-2) to (E-2) A resist underlayer film material containing a resin in which a compound is novolak-coated is coated on a substrate, and the coated resist underlayer film material is heat-treated at a temperature exceeding 300 ° C. and not more than 600 ° C. for 10 seconds to 600 seconds. And a resist underlayer film forming method characterized by comprising:

(In the general formulas (A-2) to (E-2), R ^{1 to} R ⁴ are the same or different hydrogen atoms, linear, branched or cyclic alkyl groups having 1 to 10 carbon atoms, carbon An aryl group having 6 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, and R ^{5 to} R ⁸ are each a hydrogen atom, a linear, branched or cyclic alkyl group having 1 to 6 carbon atoms, an acyl group, Alternatively, a glycidyl group, R ⁹ is a hydrogen atom, a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms, an alkoxy group, an alkenyl group having 2 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, halogen Atom, amino group, alkylmethylamino group having 1 to 4 carbon atoms, diarylamino group having 6 to 10 carbon atoms, cyano group, nitro group, R ¹⁰ and R ¹¹ are linear or branched having 1 to 10 carbon atoms M, n, p, q, r are integers of 1-6 )   3. The resist underlayer film forming method according to claim 1, wherein the resist underlayer film material is coated on a substrate by a spin coat method.   The resist underlayer film forming method according to any one of claims 1 to 3, wherein the resist underlayer film material further contains an organic solvent.   The resist underlayer film forming method according to any one of claims 1 to 4, wherein the resist underlayer film material further contains a crosslinking agent and an acid generator.   A method of forming a pattern on a substrate by lithography, wherein at least a resist underlayer film is formed on the substrate by the resist underlayer film forming method according to any one of claims 1 to 5, and the resist underlayer film A resist intermediate layer film containing a silicon atom is used to form a resist intermediate layer film, and a resist upper layer film made of a photoresist composition is formed on the resist intermediate layer film. Then, after exposing the pattern circuit region of the resist upper layer film, developing with a developing solution to form a resist pattern on the resist upper layer film, and etching the resist intermediate layer film using the obtained resist pattern as an etching mask The resist underlayer film is etched using the obtained resist intermediate layer film pattern as an etching mask, and the obtained resist Pattern forming method and forming a pattern on a substrate strike underlayer film pattern by etching the substrate with an etching mask.   A method of forming a pattern on a substrate by lithography, wherein at least a resist underlayer film is formed on the substrate by the resist underlayer film forming method according to any one of claims 1 to 5, and the resist underlayer film An inorganic hard mask intermediate film selected from a silicon oxide film, a silicon nitride film, and a silicon oxynitride film is formed on the substrate, and a resist upper film material made of a photoresist composition is used on the inorganic hard mask intermediate layer film. Forming a resist upper layer film, exposing the pattern circuit region of the resist upper layer film, developing with a developer to form a resist pattern on the resist upper layer film, and using the obtained resist pattern as an etching mask The inorganic hard mask intermediate layer film is etched, and the obtained inorganic hard mask intermediate layer film pattern is used as an etching mask. Pattern forming method strike underlayer film is etched, the resulting resist underlayer film pattern by etching the substrate with an etching mask and forming a pattern on a substrate.   A method of forming a pattern on a substrate by lithography, wherein at least a resist underlayer film is formed on the substrate by the resist underlayer film forming method according to any one of claims 1 to 5, and the resist underlayer film An inorganic hard mask intermediate layer film selected from a silicon oxide film, a silicon nitride film and a silicon oxynitride film is formed on the organic anti-reflection film, and an organic anti-reflection film is formed on the inorganic hard mask intermediate layer film. A resist upper layer film made of a photoresist composition is used to form a resist upper layer film on the film, the pattern circuit region of the resist upper layer film is exposed, and then developed with a developing solution to form a resist on the resist upper layer film. A pattern is formed, and the organic antireflection film and the inorganic hard mask intermediate film are etched using the obtained resist pattern as an etching mask. The resist underlayer film is etched using the inorganic hard mask intermediate layer film pattern as an etching mask, and the substrate is etched using the obtained resist underlayer film pattern as an etching mask to form a pattern on the substrate. Forming method.   9. The pattern forming method according to claim 7, wherein the inorganic hard mask intermediate film is formed by a CVD method or an ALD method. The resist upper layer film material does not contain a silicon atom-containing polymer, and the resist lower layer film is etched using the resist intermediate layer film as a mask, using an etching gas mainly composed of oxygen gas or hydrogen gas. The pattern formation method as described in any one of Claim 6 thru | or 9.

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