JP5141882B2 - Composition for forming resist underlayer film exhibiting barrier property and method for evaluating barrier property of resist underlayer film - Google Patents

Description

INDUSTRIAL APPLICABILITY The present invention is useful for forming a resist underlayer film that serves as a barrier for a substance that changes the resist pattern shape to diffuse into the resist in order to obtain a resist pattern having a desired shape in a lithography process in the process of manufacturing a semiconductor device. Relates to the composition. Furthermore, the present invention relates to a method for evaluating the barrier property of the resist underlayer film.

In the present specification, the barrier property means a characteristic that suppresses diffusion (movement) of a substance that changes the resist pattern shape to an upper resist layer. In this specification, a resist underlayer film that serves as a barrier for the substance to diffuse into the resist is particularly expressed as a barrier layer or a barrier film.

In the lithography process, a resist pattern is formed as a mask material for etching. Conventionally, the cross section of the resist pattern in the direction perpendicular to the substrate has, for example, an undercut shape, a T-top shape, or a footing shape, and often has a problem that it does not become a desired shape. Here, the desired shape is a shape in which the bottom of the resist pattern is a straight shape and the cross section is substantially rectangular. When the resist pattern has an undercut shape, the area where the resist pattern and the resist underlayer film are in contact with each other is narrower than that in a desired shape, so that the resist pattern is likely to collapse.

In recent years, as the resist pattern becomes finer and thinner, the solution to the above problem is becoming more and more important. However, the resist underlayer film conventionally used as an antireflection film does not necessarily have sufficient barrier properties.

By the way, Patent Document 1 discloses a composition for forming a barrier layer that reduces contamination or poisoning of a photoresist layer by a dielectric layer. The composition includes a crosslinkable polymer, which includes a phenol novolac resin.
JP 2002-128847 A

The substance that changes the resist pattern shape is considered to be an acid or a base such as an amine. Consider the case where acid diffuses from a resist underlayer film to a positive resist. Due to the acid diffusion from the resist underlayer film, the acidity becomes strong near the interface between the positive resist and the resist underlayer film, and the solubility of the positive resist in the alkaline developer near the interface increases. As a result, it is considered that the formed resist pattern has an undercut shape. On the contrary, when the base diffuses from the resist underlayer film to the positive resist, the basicity becomes strong near the interface between the positive resist and the resist underlayer film, and the solubility of the positive resist in the alkaline developer near the interface is increased. It is considered that the resist pattern to be formed becomes a footing shape.

  In the step of forming the resist pattern, for example, the baking process is performed at a temperature of 80 ° C. to 250 ° C. for 0.5 minutes to 5 minutes at least once, for example, twice. During the baking process, acid or base easily diffuses from the resist underlayer film, the substrate or the like to the resist. In addition, the change in the resist pattern shape may be caused by the low molecular component contained in the resist soaking into the resist underlayer film in the step of applying the resist.

Patent Document 1 described above describes providing a barrier layer under a photoresist, but does not describe or suggest diffusion of a substance that changes the resist pattern shape from the resist underlayer film. Furthermore, there is no description or suggestion about the barrier property evaluation method of the barrier layer.

An object of the present invention is to provide a method for evaluating the barrier property of a resist underlayer film in terms of an appropriate numerical value.

A further object of the present invention is to provide a composition for forming a resist underlayer film exhibiting barrier properties in which a resist pattern formed on the resist underlayer film has a desired shape. The resist underlayer film exhibiting this barrier property is accompanied by a resist underlayer film having antireflection characteristics when the resist is exposed with radiation such as ArF or KrF excimer laser, EUV (extreme ultraviolet), or the resist underlayer film. Without being accompanied, it is provided between the substrate and the resist. The resist underlayer film showing the barrier property of the present invention does not necessarily have antireflection properties.

  The inventors of the present invention newly devised a method for evaluating the barrier property of a resist underlayer film, and as a result of evaluating various resist underlayer films based on the method, the inventors have found a resist underlayer film particularly excellent in barrier properties. Then, it was found that in order to form a resist underlayer film having excellent barrier properties, it is necessary to use a composition containing a compound having an aromatic ring to which at least one hydroxyl group is bonded, an organic solvent, and a crosslinking agent. .

A first aspect of the present invention includes a compound having an aromatic ring to which at least one hydroxyl group is bonded, an organic solvent, and a crosslinking agent, and the compound having an aromatic ring to which at least one hydroxyl group is bonded has the following formula: (1):

[In the above formula, X represents the following formula (2), formula (3) or formula (4):

(Wherein R ^{1 to} R ⁵ each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 3 to 6 carbon atoms, a benzyl group or a phenyl group, , At least one group selected from the group consisting of an alkyl group having 1 to 6 carbon atoms, a halogen atom, an alkoxy group having 1 to 6 carbon atoms, a nitro group, a cyano group, and an alkylthio group having 1 to 6 carbon atoms. R ¹ and R ² , R ³ and R ⁴ may be bonded to each other to form a ring having 3 to 6 carbon atoms)]
It is a composition for forming the resist underlayer film which shows the barrier property which has the repeating unit structure represented by these.

The compound having a repeating unit structure represented by the formula (1) is, for example, the following formula (5):

Comprising monomer units represented in.

A second aspect of the present invention includes a compound having an aromatic ring to which at least one hydroxyl group is bonded, an organic solvent, and a crosslinking agent, wherein the compound having an aromatic ring to which at least one hydroxyl group is bonded is represented by the following formula: (6):

(In the above formula, R ⁶ and R ⁷ each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and Y ¹ and Y ² each independently represent a phenol derivative)
It is a composition for forming the resist underlayer film which shows the barrier property which has the repeating unit structure represented by these. Here, the phenol derivative is one in which at least one hydrogen atom in the phenol benzene ring is substituted with an organic group (a substituent containing a carbon atom).

The compound having a repeating unit structure represented by the formula (6) is, for example, the following formula (7):

[In the above formula, Z ^{1 to} Z ⁴ are each independently a hydrogen atom or the following formula (8a ):

(In the above formula, Z ^{1 to} Z ⁴ are the same as above)]. The compound having the repeating unit structure represented by the formula (7) is branched poly-hydroxystyrene (Branched Poly- (hydroxy) styrene).

In the first and second aspects of the present invention, the compound having an aromatic ring to which at least one hydroxyl group is bonded is a polymer, an oligomer, or a combination thereof. The aromatic ring to which at least one hydroxyl group of the compound is bonded may be introduced into the main chain of the polymer (oligomer) or may be introduced into the side chain.

A third aspect of the present invention includes a compound having an aromatic ring to which at least one hydroxyl group is bonded, an organic solvent, and a crosslinking agent, and the compound having an aromatic ring to which at least one hydroxyl group is bonded has the following formula: (9):

It is a composition for forming the resist underlayer film which has the structure represented by this, and shows barrier property.

In the third aspect of the present invention, the compound having an aromatic ring to which at least one hydroxyl group is bonded is an oligomer having a structure represented by the formula (9) at the end, the following formula (10):

Or a combination thereof.

The organic solvent contained in the resist underlayer film forming composition showing the barrier property of the present invention is, for example, propylene glycol monomethyl ether (PGME), propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monopropyl ether, methyl ethyl ketone, ethyl lactate, It consists of at least one selected from cyclohexanone, γ-butyrolactone, and N-methylpyrrolidone.

When the component of the resist underlayer film forming composition showing the barrier property of the present invention excluding the organic solvent is defined as a solid content, the ratio of the solid content is, for example, 1% by mass or more and 30% with respect to the composition of the present invention. It is below mass%.

The crosslinking agent contained in the resist underlayer film forming composition showing the barrier property of the present invention is, for example, a nitrogen-containing compound having 2 to 4 nitrogen atoms bonded with methylol groups or alkoxymethyl groups. Specific examples of the crosslinking agent include hexamethoxymethyl melamine, tetramethoxymethyl benzoguanamine, 1,3,4,6-tetrakis (methoxymethyl) glycoluril, 1,3,4,6-tetrakis (butoxymethyl) glycoluril, 1 , 3,4,6-tetrakis (hydroxymethyl) glycoluril, 1,3-bis (hydroxymethyl) urea, 1,1,3,3-tetrakis (butoxymethyl) urea and 1,1,3,3-tetrakis (Methoxymethyl) urea etc. are mentioned. The ratio of the crosslinking agent to the solid content is, for example, 10% by mass or more and 70% by mass or less, preferably 20% by mass or more and 50% by mass or less. As the proportion of the crosslinking agent increases, the barrier property of the resist underlayer film to be formed tends to increase. However, when the proportion of the crosslinking agent exceeds a predetermined proportion, the barrier property hardly improves. When the crosslinking agent is not included, the formed resist underlayer film has low barrier properties and cannot be used as a barrier layer (barrier film).

The composition for forming a resist underlayer film showing the barrier property of the present invention may further contain a compound showing acidity as an additive. A compound showing acidity has an action of promoting a crosslinking reaction. For example, a sulfonic acid compound corresponds to a compound showing acidity, and specific examples thereof include p-toluenesulfonic acid, trifluoromethanesulfonic acid, pyridinium-p-toluenesulfonic acid, camphorsulfonic acid, 5-sulfosalicylic acid, 4-chlorobenzenesulfone. Examples include acid, 4-hydroxybenzenesulfonic acid, benzenedisulfonic acid, 1-naphthalenesulfonic acid, and pyridinium-1-naphthalenesulfonic acid. The ratio of the compound which shows the acidity with respect to solid content is 0.1 to 10 mass%, for example.

The resist underlayer film forming composition exhibiting barrier properties of the present invention may further contain a surfactant as an additive. The surfactant is an additive for improving the coating property to the substrate or the base. Known surfactants such as nonionic surfactants and fluorine-based surfactants can be used.

The method for forming a resist pattern used in the manufacture of a semiconductor device using the resist underlayer film forming composition showing the barrier property of the present invention comprises applying a first resist underlayer film forming composition on a substrate and baking it. A step of forming a first resist underlayer film and a composition for forming a resist underlayer film exhibiting barrier properties according to the present invention are applied onto the first resist underlayer film and baked to form a second resist underlayer film. A step of applying a resist onto the second resist underlayer film, baking, a step of exposing the resist, and a step of developing the resist after exposure. If necessary, a PEB (Post Exposure Bake) process is further added between the exposure process and the development process. In other words, the second resist underlayer film can be referred to as a barrier layer (barrier film).

The substrate to which the first resist underlayer film forming composition is applied is, for example, a semiconductor substrate, typically a silicon wafer, but an SOI (Silicon on Insulator) substrate, gallium arsenide (GaAs), indium phosphide ( A compound semiconductor wafer such as InP) or gallium phosphide (GaP) may be used. For example, a glass substrate, a quartz substrate, or a ceramic substrate may be used instead of the semiconductor substrate. An insulating film, a semiconductor film, a conductive film, or the like may already be formed over any substrate.

For the exposure performed on the resist, for example, an ArF excimer laser is used. Instead of the ArF excimer laser, a KrF excimer laser or EUV (wavelength of about 13.5 nm) may be used. You may expose using an electron beam (EB). The resist may be either a positive resist or a negative resist, and an ArF excimer laser, a KrF excimer laser, EUV, or a chemically amplified resist that is sensitive to an electron beam can be used.

A fourth aspect of the present invention,
The first resist underlayer film is formed on the substrate by baking under a first condition, to quantify the amount S _U sublimate generating the first resist underlayer film when baked at a second condition ,
Quantifying the amount S _{B of} sublimate generated when the second resist underlayer film is formed on the substrate by baking under the second condition;
Forming the first resist underlayer film on the substrate by baking under the first condition, and baking the second resist underlayer film over the first resist underlayer film under the second condition. The amount of sublimate generated when forming by SU _{+ B} is quantified,
It is a method for evaluating the barrier property of a resist underlayer film, wherein the barrier property of the second resist underlayer film is evaluated using the determined amounts of sublimates S _U , S _B and S _{U + B.}

In the method for evaluating the barrier property of the resist underlayer film of the present invention, it should be noted that only the amount of sublimate generated when baking under the second condition is quantified. The barrier properties of the second resist underlayer film, S as U _{+ B} and the value of the difference is small and S _B with S _B is small, or S _{U + B} and as the value of the difference is small and S _U and S _B is greater , high it is suggested.

In the method for evaluating the barrier property of the resist underlayer film of the present invention, the quantified amounts of the sublimates S _U , S _B and S _{U + B} are expressed by, for example, the following formula:
[1- (S _{U + B} −S _B ) / S _U ] × 100
The barrier property of the second resist underlayer film is evaluated by a numerical value calculated by substituting for. In the present specification, this numerical value is referred to as a “barrier rate” in units of “%”. It is judged that the barrier property is higher as the barrier rate is higher (closer to 100%), and a resist underlayer film having a barrier rate of 80% or more is regarded as being particularly effective as a barrier layer (barrier film). Thus, the barrier property of the resist underlayer film can be quantified by replacing it with the sublimate permeability of the resist underlayer film. The barrier properties of the resist underlayer film can be easily evaluated by digitization.

In the fourth aspect of the present invention, the first condition is a temperature of 130 ° C. to 180 ° C. and a time of 0.5 minutes to 5 minutes, and the second condition is a temperature of 130 ° C. and 250 ° C. The time is from 0.5 minutes to 5 minutes. The temperature of the first condition is preferably lower than the temperature of the second condition. This is because the amount of sublimation generated when the first resist underlayer film is formed by baking under the first condition is reduced as much as possible, and then the sublimation generated when baking under the second condition is reduced. The amount can be increased, and the accuracy of the barrier property evaluation based on the quantitative result of the sublimate amount can be increased. The amount of sublimate that is actually quantified is a level expressed in nanogram (ng) units, and is very small.

The amounts of the sublimates S _U , S _B and S _{U + B} are quantified by, for example, a QCM (quartz crystal microbalance) method. As the QCM method, a method using an apparatus described in International Publication No. 2007/111147 pamphlet can be employed.

  By the method for evaluating the barrier property of the resist underlayer film of the present invention, the high barrier property of the resist underlayer film can be easily evaluated. Therefore, a resist underlayer film having a high barrier property can be found by this barrier property evaluation method, and the resist underlayer film can be employed as a barrier layer (barrier film). Furthermore, the resist underlayer film having a high barrier property found by this barrier property evaluation method is less dependent on the film thickness of the barrier rate. That is, the barrier property is high even with a relatively thin film thickness, and is effective as a barrier layer (barrier film).

By using the composition for forming a resist underlayer film exhibiting the barrier property of the present invention, a desired shape (a cross section in a direction perpendicular to the substrate is formed on the resist underlayer film having a high barrier property formed from the composition. A (rectangular) resist pattern can be formed without collapsing.

  The barrier property evaluation method of the present invention for evaluating the barrier property of the second resist underlayer film will be described below.

  A first resist underlayer film forming composition containing a polymer, an organic solvent, and a crosslinking agent is prepared. As the polymer, for example, an acrylic polymer used in the composition for forming an antireflection film is used. Furthermore, an acid generator may be added. The first resist underlayer film forming composition is applied onto a substrate by a spinner or the like, and cured by baking at a first condition, for example, at 180 ° C. for 1 minute to form a first resist underlayer film. For example, a silicon wafer is used as the substrate.

  Next, a second resist underlayer film forming composition (not containing an acid generator) is prepared. After applying this second resist underlayer film forming composition on the formed first resist underlayer film with a spinner or the like, the sublimation amount measuring device described in International Publication No. 2007/111147 pamphlet is used. A substrate coated with the composition is placed. This sublimation amount measuring apparatus includes at least a hot plate for heating a substrate and a crystal resonator (QCM sensor) on which an electrode is formed so that the sublimate adheres to the surface of the crystal resonator (electrode). It has become. Then, by utilizing the fact that the frequency of the crystal resonator changes due to the attachment of the sublimate, it is possible to measure a small amount of mass change. As the electrode material, for example, a material mainly composed of silicon and aluminum (AlSi) or gold (Au) is used. Since what is actually measured by the sublimation amount measuring device is the frequency change ΔF of the crystal resonator, ΔF is converted into a mass change Δm by a predetermined conversion formula. As a conversion formula, Δm = ΔF × 1.07 can be used.

Then, the composition for forming the second resist underlayer film applied on the first resist underlayer film is cured by baking at a second condition, for example, at 205 ° C. for 1 minute, so that the second resist underlayer film is formed. Form. The amount of sublimate generated when baking under the second condition is quantified by the above-mentioned sublimate amount measuring apparatus, and the result is set to _{SU + B.}

On the other hand, a first resist underlayer film is formed on the substrate (silicon wafer) by the same method and conditions as described above. Thereafter, the substrate on which the first resist underlayer film is formed is placed in the above-described sublimation amount measuring apparatus without applying the second resist underlayer film forming composition. Then, the first resist underlayer film was baked under the second condition, to quantify the amount of sublimate generated during its to the result with S _U.

In addition, a second resist underlayer film-forming composition (not containing an acid generator) is applied onto a substrate (silicon wafer) on which the first resist underlayer film is not formed by using a spinner or the like, and the amount of the sublimate described above installed in the measurement device. Then, the second resist underlayer film forming composition applied on the substrate is cured by baking under the second condition to form a second resist underlayer film. The amount of sublimate generated when baking under the second condition is quantified, and the result is S _B.

Finally, the obtained result is expressed by the formula: [1- (S _{U + B} −S _B ) / S _U ] × 100
Substituting into, the barrier rate (%) is calculated.

  When the barrier rate is 80% or more, the second resist underlayer film is obtained from a composition containing a compound having an aromatic ring to which at least one hydroxyl group is bonded, an organic solvent, and a crosslinking agent. A compound having an aromatic ring to which at least one hydroxyl group is bonded is not necessarily a polymer. On the contrary, the second resist underlayer film obtained from the composition not containing the compound having an aromatic ring does not have a barrier rate of 80% or more.

Specific examples of the compound having an aromatic ring to which at least one hydroxyl group is bonded are shown in the following formulas (11) to (15), but are not limited to these specific examples.

  The synthesis of the compound constituting the solid content of the resist underlayer film forming composition and the adjustment of the resist underlayer film forming composition will be described with specific examples.

The weight average molecular weight shown in the following synthesis examples of this specification is a measurement result by gel permeation chromatography (hereinafter abbreviated as GPC). The measurement conditions etc. are as follows using the Tosoh Co., Ltd. product GPC apparatus for a measurement.
GPC column: Shodex (registered trademark) and Asahipak (registered trademark) (Showa Denko KK)
Column temperature: 40 ° C
Solvent: N, N-dimethylformamide (DMF)
Flow rate: 0.6ml / min
Standard sample: Polystyrene (Tosoh Corporation)

<Synthesis Example 1>
Benzyl methacrylate (Tokyo Chemical Industry Co., Ltd.) 13.2 g (0.08 mol), hydroxypropyl methacrylate (Tokyo Chemical Industry Co., Ltd.) 8.0 g (0.07 mol), and γ-butyrolactone methacrylate (Tokyo Chemical Industry Co., Ltd.) 18.8 g (0.15 mol) was dissolved in 131.6 g of ethyl lactate, and the temperature was raised to 70 ° C. When the ethyl lactate solution was stabilized at 70 ° C., a solution prepared by dissolving 0.4 g of azobisisobutyronitrile in 30 g of ethyl lactate was added dropwise. After completion of the dropwise addition, the solution containing the reaction product was obtained by stirring at 70 ° C. for 24 hours. When the GPC analysis of the obtained reaction product was conducted, the weight average molecular weight was 28000 in standard polystyrene conversion. This reaction product does not have a hydroxyl group bonded to an aromatic ring, as represented by the following formula.

<Synthesis Example 2>
Monoallyl diglycidyl isocyanuric acid (Shikoku Kasei Kogyo Co., Ltd., trade name: MADGIC) 23.346 g, diethylbarbituric acid 15.473 g, and benzyltriethylammonium chloride 0.845 g as a catalyst to propylene glycol monomethyl ether 160.34 g After dissolving, reaction was performed at 130 ° C. for 4 hours to obtain a solution containing the reaction product. When the GPC analysis of the obtained reaction product was conducted, the weight average molecular weight was 9700 in standard polystyrene conversion. This reaction product does not have a hydroxyl group bonded to an aromatic ring as represented by the following formula.

<Synthesis Example 3>
Monoallyl diglycidyl isocyanuric acid (Shikoku Kasei Kogyo Co., Ltd., trade name: MADGIC) 23.447 g, 5-hydroxyisophthalic acid 15.366 g, and benzyltriethylammonium chloride 0.848 g are dissolved in propylene glycol monomethyl ether 160.34 g. And then reacted at 130 ° C. for 4 hours to obtain a solution containing the reaction product. As a result of proton NMR analysis of the obtained reaction product, an aromatic hydroxyl group peak was confirmed. Moreover, when the GPC analysis of the obtained reaction product was performed, the weight average molecular weight was 17000 in standard polystyrene conversion. This reaction product is represented by the formula (11).

<Synthesis Example 4>
Monoallyl diglycidyl isocyanuric acid (Shikoku Kasei Kogyo Co., Ltd., trade name: MADGIC) 22.773 g, 5-methoxyisophthalic acid 16.074 g, and benzyltriethylammonium chloride 0.824 g as a catalyst, 160.33 g of propylene glycol monomethyl ether Then, it was reacted at 130 ° C. for 4 hours to obtain a solution containing the reaction product. When the GPC analysis of the obtained reaction product was performed, the weight average molecular weight was 7000 in standard polystyrene conversion. This reaction product does not have a hydroxyl group bonded to an aromatic ring as represented by the following formula.

<Synthesis Example 5>
Monoallyl diglycidyl isocyanuric acid (Shikoku Kasei Kogyo Co., Ltd., trade name: MADGIC) 37.720 g, tartaric acid 20.371 g, and 1.365 g of ethyltriphenylphosphonium bromide as a catalyst were dissolved in 140.54 g of propylene glycol monomethyl ether. Thereafter, the reaction was carried out at 130 ° C. for 4 hours to obtain a solution containing the reaction product. When the GPC analysis of the obtained reaction product was conducted, the weight average molecular weight was 10,000 in standard polystyrene conversion. This reaction product does not have a hydroxyl group bonded to an aromatic ring as represented by the following formula.

<Synthesis Example 6>
Tris (2,3-epoxypropyl) isocyanuric acid (Nissan Chemical Industry Co., Ltd., trade name: TEPIC [registered trademark]) 39.159 g, 3,5-dihydroxybenzoic acid 60.841 g, propylene glycol monomethyl ether 100.00 g Then, it was reacted at 130 ° C. for 24 hours to obtain a solution containing the reaction product. When the GPC analysis of the obtained reaction product was performed, the weight average molecular weight was 1000 in standard polystyrene conversion. This reaction product is represented by the above formula (15), for example, and has a hydroxyl group bonded to an aromatic ring.

  To 24.379 g of the solution containing 4.905 g of the reaction product obtained in Synthesis Example 1, 32.04 g of ethyl lactate, 22.08 g of propylene glycol monomethyl ether acetate, triphenylsulfonium trifluoromethanesulfonate (Midori Kagaku) as an acid generator Co., Ltd., trade name: TPS-105 0.192 g, tetramethoxymethyl glycoluril (Nippon Cytec Industries, Ltd., trade name: POWDERLINK [registered trademark] 1174) 1.226 g, and pyridinium-p-toluenesulfonate 0 0.0766 g was added to make a solution. Then, it filtered using the polyethylene micro filter with a hole diameter of 0.10 micrometer, and prepared the 1st composition for resist underlayer film formation.

<Comparative Example 1>
To 12.549 g of the solution containing 2.510 g of the reaction product obtained in Synthesis Example 1, 43.7 g of propylene glycol monomethyl ether, 23.4 g of propylene glycol monomethyl ether acetate, tetramethoxymethyl glycoluril (Nippon Cytec Industries, Ltd.) (Trade name: POWDERLINK [registered trademark] 1174) and 0.663 g of pyridinium-p-toluenesulfonate were added to obtain a solution. Then, it filtered using the polyethylene micro filter with a hole diameter of 0.10 micrometer, and prepared the 2nd composition for resist lower layer film formation (henceforth the composition A).

<Comparative Example 2>
Using the solution containing the reaction product obtained in Synthesis Example 2, the same treatment as in Comparative Example 1 was performed to prepare a second resist underlayer film forming composition (hereinafter referred to as composition B).

<Example 1>
Using the solution containing the reaction product obtained in Synthesis Example 3, the same treatment as in Comparative Example 1 was performed to prepare a second resist underlayer film forming composition (hereinafter referred to as composition C).

<Example 2>
Using a branched poly-parahydroxystyrene (DuPont Electronic Polymer Co., Ltd., trade name: PHS-B5E), the same treatment as in Comparative Example 1 was performed, and a second resist underlayer film forming composition (hereinafter, composition) It was adjusted) that D. The used branched poly-parahydroxystyrene has a hydroxyl group bonded to an aromatic ring and was subjected to GPC analysis. The weight average molecular weight was 5000 in terms of standard polystyrene.

<Comparative Example 3>
Using the solution containing the reaction product obtained in Synthesis Example 4, the same treatment as in Comparative Example 1 was performed to prepare a second resist underlayer film forming composition (hereinafter referred to as composition E).

<Comparative Example 4>
Using the solution containing the reaction product obtained in Synthesis Example 5, the same treatment as in Comparative Example 1 was performed to prepare a second resist underlayer film forming composition (hereinafter referred to as composition F).

<Example 3>
Using the solution containing the reaction product obtained in Synthesis Example 6, the same treatment as in Comparative Example 1 was performed to prepare a second resist underlayer film forming composition (hereinafter referred to as composition G).

(Evaluation of the photoresist pattern shape)
The first resist underlayer film-forming composition containing an acid generator is applied onto a silicon wafer by a spinner and baked on a hot plate at 205 ° C. for 1 minute to form a first resist underlayer film (thickness 0). .023μm) was formed. Three silicon wafers on which such a first resist underlayer film was formed were prepared.

Next, using the composition A, the composition C, and the composition D, a second resist underlayer film was formed on each of the first resist underlayer films (baked at 205 ° C. for 1 minute). On each of these second resist underlayer films, a commercially available photoresist solution (Tokyo Ohka Kogyo Co., Ltd., trade name: TArF-P6111ME) was applied with a spinner and heated on a hot plate at 130 ° C. for 1 minute. A photoresist layer was formed.

Then, using an ArF stepper manufactured by Nikon Corporation (wavelength: 193 nm, NA: 0.55 (Conventional)), after development, a line having a photoresist line width of 0.08 μm and a line width of 0.1 μm Exposure was performed through a mask designed to form nine lines. After exposure of the photoresist, PEB (Post Exposure Bake) is performed at 130 ° C. for 1 minute, and after cooling, developed using a 0.26N tetramethylammonium hydroxide developer in an industrial standard 60-second single paddle process. Then, a photoresist pattern was formed.

Further, for comparison, a silicon wafer was prepared which differs only in that the first resist underlayer film was not formed (that is, a photoresist pattern formed with any of the above-described three types of second resist underlayer films).

The cross-sectional shape of the resist pattern when the first resist underlayer film is not formed is shown in Condition-1 in FIG. On the other hand, Condition-2 in FIG. 1 shows a cross-sectional shape of the photoresist pattern when the second resist underlayer film is laminated on the first resist underlayer film containing the acid generator. FIG. 2 shows a state in which a first resist underlayer film 102 and a second resist underlayer film 103 containing an acid generator are stacked on a silicon wafer 101.

  The results shown in FIG. 1 show that when the second resist underlayer film is formed using the composition A, the cross-sectional shape of the resist pattern greatly changes depending on the presence or absence of the first resist underlayer film containing an acid generator, The presence of the first resist underlayer film indicates that the photoresist pattern collapses. That is, the second resist underlayer film formed using the composition A suggests that the barrier property against acid diffusion is low. On the other hand, when the second resist underlayer film is formed using the composition C or the composition D, the cross-sectional shape of the resist pattern hardly changes depending on the presence or absence of the first resist underlayer film containing the acid generator. That is, it is suggested that the second resist underlayer film formed using the composition C or the composition D has a high barrier property against acid diffusion.

(Barrier properties of the evaluation)
Sublimation generated from a single layer of a first resist underlayer film (film thickness of about 80 nm) formed on a silicon wafer using the above-described first resist underlayer film forming composition (but not containing an acid generator). the amount S _U of the object and quantified by sublimation quantity measuring device described above. The amount S _B of composition A to sublimate generated when the second resist underlayer film (film thickness: about 30 nm) single layer to form respectively on a silicon wafer using a composition G, the aforementioned sublimation quantity measuring device in was quantified. This occurs when the first resist underlayer film (film thickness of about 80 nm) is formed on a silicon wafer, and the second resist underlayer film (film thickness of about 30 nm) is formed thereon as shown in FIG. The amount of sublimation SU _{+ B} was quantified with the above-mentioned sublimation amount measuring apparatus. The baking condition at the time of quantification is 205 ° C. for 2 minutes. As the baking time is increased, the amount of sublimate increases, but the amount of sublimate hardly increases after a predetermined time.

Table 1 shows the results of calculating the barrier rate from the quantified values of S _U , S _B and S _{U + B} using the following formula.
Barrier rate (%) = [1− (S _{U + B} −S _B ) / S _U ] × 100

  Table 1 shows that the second resist underlayer film formed using the composition C and the second resist underlayer film formed using the composition D have high barrier properties. Table 1 further shows that the second resist underlayer film formed using the composition G also has a high barrier property. The reaction product obtained in Synthesis Example 6 contained in the composition G is not a polymer, but is considered to be an oligomer, a monomer, or a combination thereof, from the weight average molecular weight determined by GPC analysis. The second resist underlayer film formed using the composition C, the second resist underlayer film formed using the composition D, and the second resist underlayer film formed using the composition G are: It was found that the film has a sufficient barrier property as a barrier layer (barrier film).

  On the other hand, a second resist underlayer film formed using the composition A, a second resist underlayer film formed using the composition B, a second resist underlayer film formed using the composition E, And the 2nd resist underlayer film formed using the composition F resulted in a low barrier property. This result indicates that it is inappropriate to refer to these second resist underlayer films as barrier layers (barrier films).

In Table 1, each of the second resist underlayer films showing the result that the barrier rate is 80% or more includes a compound having an aromatic ring (phenolic hydroxyl group) to which at least one hydroxyl group is bonded. Formed from. On the other hand, none of the second resist underlayer films showing the result that the barrier rate is much lower than 80% is formed from a composition containing such a compound having an aromatic ring (Synthesis Examples 1, 2, 4). , 5).

(Film thickness dependence of the barrier rate)
FIG. 3 shows the result of calculating the barrier rate for the second resist underlayer films having different film thicknesses. Two types of films were used as the second resist underlayer film. One is formed from a composition containing a compound having a phenolic hydroxyl group, and the other is formed from a composition not containing a compound having a phenolic hydroxyl group. The second resist underlayer film showing a high barrier property with a thin film thickness of about 30 nm is formed from a composition containing a compound having a phenolic hydroxyl group, and the change in the barrier rate due to the change in the film thickness is small. The second resist underlayer film having a low barrier property at a thin film thickness of about 30 nm cannot increase the barrier ratio unless the film thickness is increased.

(Relationship between barrier rate and film density)
The density of the second resist underlayer film formed using the composition A and the second resist underlayer film formed using the composition C (both having a film thickness of about 100 nm) was determined using an X-ray diffraction apparatus manufactured by PANalytical. When measured using (X′Pert PRO MRD), the former was 1.26 g / cm ³ and the latter was 1.41 g / cm ³ . This result suggests that the barrier rate tends to be higher as the film density is higher.

It is a figure which compares the cross-sectional shape of a resist pattern. It is a figure which shows a mode that the 1st resist underlayer film and the 2nd resist underlayer film are laminated | stacked on a silicon wafer. It is a figure which shows the change of the barrier rate with respect to the film thickness of a 2nd resist lower layer film.

Explanation of symbols

101 Silicon wafer 102 First resist underlayer film 103 Second resist underlayer film

Claims (9)

The compound having an aromatic ring to which at least one hydroxyl group is bonded, an organic solvent and a crosslinking agent, and the compound having an aromatic ring to which at least one hydroxyl group is bonded are represented by the following formula (6):

(In the above formula, R ⁶ and R ⁷ each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and Y ¹ and Y ² each independently represent a phenol derivative)
A composition for forming a resist underlayer film exhibiting barrier properties, having a repeating unit structure represented by: The composition for forming a resist underlayer film exhibiting barrier properties according to claim 1, wherein the compound having a repeating unit structure represented by the formula (6) is represented by the following formula (7):

[In the above formula, Z ^{1 to} Z ⁴ are each independently a hydrogen atom or the following formula (8a ):

(Z ^{1 to} Z ² in the above formula are the same as above)] A composition for forming a resist underlayer film having a barrier property and having a repeating unit structure represented by: 3. The composition for forming a resist underlayer film exhibiting barrier properties according to claim 1 or 2, wherein the compound having an aromatic ring to which at least one hydroxyl group is bonded is a polymer, an oligomer, or a combination thereof. A composition for forming a resist underlayer film exhibiting barrier properties. The process for apply | coating and baking the 1st composition for resist underlayer film formation on a board | substrate, and forming a 1st resist underlayer film, The barrier property as described in any one of Claim 1 thru | or 3 is shown. A step of applying a resist underlayer film forming composition on the first resist underlayer film and baking to form a second resist underlayer film, and applying and baking a resist on the second resist underlayer film A resist pattern forming method used for manufacturing a semiconductor device, comprising: a step; a step of exposing the resist; and a step of developing the resist after exposure. The first resist underlayer film is formed on the substrate by baking under a first condition, to quantify the amount S _U sublimate generating the first resist underlayer film when baked at a second condition ,
Quantifying the amount S _{B of} sublimate generated when the second resist underlayer film is formed on the substrate by baking under the second condition;
Forming the first resist underlayer film on the substrate by baking under the first condition, and baking the second resist underlayer film over the first resist underlayer film under the second condition. The amount of sublimate generated when forming by SU _{+ B} is quantified,
A barrier property evaluation method for a resist underlayer film, wherein the barrier property of the second resist underlayer film is evaluated using the determined amounts of sublimates S _U , S _B and S _{U + B.} The amount S _U , S _B and S _{U + B} of the sublimate quantified in the barrier property evaluation method for a resist underlayer film according to claim 5 is expressed by the following formula:
[1- (S _{U + B} −S _B ) / S _U ] × 100
The barrier property evaluation method of a resist underlayer film which evaluates the barrier property of a 2nd resist underlayer film with the numerical value substituted by substituting and calculating. 7. The resist underlayer film barrier property evaluation method according to claim 5, wherein the first condition is a temperature of 130 ° C. or higher and 180 ° C. or lower and a time of 0.5 minutes or longer and 5 minutes or shorter, The method for evaluating the barrier property of a resist underlayer film, wherein the conditions are a temperature of 130 ° C. to 250 ° C. and a time of 0.5 minutes to 5 minutes. The barrier property evaluation method for a resist underlayer film according to claim 7, wherein the temperature of the first condition is lower than the temperature of the second condition. 9. The method for evaluating barrier properties of a resist underlayer film according to claim 5, wherein the amounts of sublimates S _U , S _B and S _{U + B} are quantified by a QCM (quartz crystal microbalance) method. A method for evaluating the barrier property of a resist underlayer film.