KR100779442B1 - Silsesquioxane resin, positive resist composition, layered product including resist, and method of forming resist pattern - Google Patents

Abstract

Provided are a silsesquioxane resin, a positive resist composition, a resist laminate, and a resist pattern forming method capable of reducing degassing, and further, a silicon-containing resist composition and a resist pattern forming method suitable for immersion lithography are provided. The silsesquioxane resin is represented by the following general formula [wherein, R ¹ and R ² are each independently a linear, branched or cyclic saturated aliphatic hydrocarbon group; R ³ is an acid dissociable, dissolution inhibiting group consisting of a hydrocarbon group containing a monocyclic or polycyclic group; R ⁴ is a hydrogen atom or a linear, branched or cyclic alkyl group; X is an alkyl group having 1 to 8 carbon atoms in which at least one hydrogen atom is substituted with a fluorine atom; m has an integer represented by the integer of 1-3.

Silsesquioxane Resin, Positive Resist Composition

Description

Silsesquioxane resin, positive resist composition, resist laminate, and resist pattern forming method {SILSESQUIOXANE RESIN, POSITIVE RESIST COMPOSITION, LAYERED PRODUCT INCLUDING RESIST, AND METHOD OF FORMING RESIST PATTERN}

The present invention relates to a silsesquioxane resin used for a positive resist composition used for forming a resist pattern using high energy light or an electron beam, a positive resist composition containing the silsesquioxane resin, and a positive resist thereof. The above-mentioned used for the resist pattern forming method including the resist laminated body used for the upper layer in the two layers used for a two-layer resist process, the resist pattern formation method using this resist laminated body, and the immersion lithography (immersion exposure) process. A positive resist composition, and a method of forming a resist pattern including an immersion lithography process using the positive resist composition.

In the manufacture of a semiconductor device or a liquid crystal display device, a lithography step of forming a circuit pattern (resist pattern) in a resist on a substrate, and an insulating film or a conductive film formed as a base on a substrate, using the resist pattern as a mask material, partially The etching process of etching removal is performed.

In recent years, with the advance of lithography technology, the miniaturization of a resist pattern is progressing rapidly. In recent years, the resolution which can form the line-and-space of 100 nm or less, and also the isolation pattern of 70 nm or less is calculated | required.

As a method of miniaturization, shortening of the exposure light source is generally performed. Specifically, ultraviolet rays typified by g-ray and i-ray have conventionally been used, but mass production using KrF excimer laser (248 nm) has been started, and ArF excimer laser (193 nm) has begun to be introduced. Furthermore, F ₂ excimer laser (157 nm), EUV (ultra-ultraviolet), electron beam, X-ray, soft X-ray, etc. which are shorter wavelengths are also examined.

As a resist material that satisfies high-resolution conditions capable of reproducing fine-dimensional patterns, a base resin in which alkali solubility is increased by the action of an acid and an acid generator that generates an acid by exposure are dissolved in an organic solvent. So-called positive chemically amplified resist compositions are known. Recently, for example, a chemically amplified resist composition suitable for an exposure light source having a short wavelength of 200 nm or less has also been proposed (for example, Patent Document 1).

However, although chemically amplified resists have high sensitivity and high resolution, it is not easy to form resist patterns of high aspect ratio resist patterns required for dry etching characteristics, for example, to form patterns having aspect ratios of 4-5. There was a problem that pattern collapse occurred.

On the other hand, as one of the methods which can form a high aspect ratio resist pattern with high resolution, the two-layer resist method using the chemically amplified resist is proposed (for example, refer patent document 2, 3). In this method, first, an organic film is formed as a lower resist layer on a substrate, and then an upper resist layer is formed thereon using a chemically amplified resist containing a specific silicon-containing polymer. Subsequently, after forming a resist pattern in the upper resist layer by photolithography, it is etched as a mask to transfer the resist pattern to the lower resist layer, thereby forming a resist pattern having a high aspect ratio.

On the other hand, silicon-containing resist compositions which are preferably used in resist pattern formation methods including immersion lithography (immersion exposure) processes described in Non-Patent Documents 1 to 3 and the like are desired, but are not reported at all. Not.

[Patent Document 1]

Japanese Unexamined Patent Publication No. 2002-162745

[Patent Document 2]

Japanese Unexamined Patent Publication No. 6-202338

[Patent Document 3]

Japanese Patent Application Laid-open No. Hei 8-29987

[Non-Patent Document 1]

Journal of Vacuum Science & Technology B (USA), 1999, Vol. 17, No. 6, pp. 3306-3309

[Non-Patent Document 2]

Journal of Vacuum Science & Technology B (USA), 2001, Vol. 19, No. 6, pages 2353-2356

[Non-Patent Document 3]

Proceedings of SPIE (USA), 2002, Volume 4471, pp. 459-465

The chemically amplified resist used in the two-layer resist method as described above is not a problem when a relatively long wavelength light source such as i-line is used, but a high energy light having a relatively short wavelength of 200 nm or less ( For example, when an ArF excimer laser or the like) or an electron beam is used as a light source, it is difficult to form a resist pattern at high resolution because absorption is large and transparency is low. In addition, there is a problem that organic gas is generated (degassed) from the resist during exposure to contaminate the exposure apparatus or the like. The organic gases can be broadly classified into two types. The organic non-silicon gases generated from the resist solvent or when the organic silicon-based gas and the acid dissociable, dissolution inhibiting group generated by the decomposition of the silicon-carbon bond in the silicon-containing polymer are dissociated. have. Both have problems, such as reducing the permeability of the lens of the said exposure apparatus. In particular, it is difficult to remove the electron gas once attached to the lens, which is a big problem.

Disclosure of the Invention

Therefore, an object of the present invention is to provide a silsesquioxane resin, a positive resist composition, a resist laminate, and a resist pattern forming method which have high transparency and can prevent such degassing.

 Another object of the present invention is to provide a silicon-containing resist composition and a resist pattern forming method suitable for immersion lithography.

MEANS TO SOLVE THE PROBLEM As a result of earnestly examining, the present inventors examined the silsesquioxane resin which has a specific structural unit, the positive resist composition containing this silsesquioxane resin as a base resin, the resist laminated body containing this positive resist composition, and the resist The resist pattern formation method using a laminated body, the positive resist composition containing a silsesquioxane resin, and the resist pattern formation method using the positive resist composition discovered that the said subject solved, and completed this invention.

That is, the 1st aspect of this invention which solves the said subject is the following general formula [1] and [2]:

[Tue 6]

[Wherein, R ¹ and R ² are each independently a linear, branched or cyclic saturated aliphatic hydrocarbon group, and R ³ is an acid dissociable, dissolution inhibiting group consisting of a hydrocarbon group containing an aliphatic monocyclic or polycyclic group; R ⁴ is a hydrogen atom or a linear, branched or cyclic alkyl group, each X is an alkyl group having 1 to 8 carbon atoms in which at least one hydrogen atom is independently substituted with a fluorine atom, and m is an integer of 1 to 3 ]

Silsesquioxane resin (Hereinafter, it may be called "silsesquioxane resin (A1).") Which has a structural unit represented by the following.

The 2nd aspect of this invention which solves the said subject is the positive containing the resin component (A) which alkali solubility increases by the action of an acid, and the acid generator component (B) which generate | occur | produces an acid by exposure. As a type | mold resist composition, the said (A) component contains the silsesquioxane resin (A1) of the said 1st aspect, It is a positive resist composition characterized by the above-mentioned.

A third aspect of the present invention for solving the above problems is a resist laminate in which a lower resist layer and an upper resist layer are laminated on a support, wherein the lower resist layer is insoluble in an alkaline developer and dry-etched. The upper resist layer consists of the positive resist composition of the said 2nd aspect, It is a resist laminated body characterized by the above-mentioned.

The 4th aspect of this invention which solves the said subject selectively exposes the resist laminated body of the said 3rd aspect, performs post-exposure heating (PEB), alkali-develops, and the said upper resist layer After the resist pattern (I) is formed in the substrate, dry etching is performed using the resist pattern (I) as a mask, and the resist pattern (II) is formed in the lower resist layer.

In addition, a fifth aspect of the present invention is a resist composition used in a resist pattern forming method including a step of immersion exposure, wherein a line and space of 130 nm is 1 by a lithography process of a normal exposure using a light source having a wavelength of 193 nm. The sensitivity at the time of forming a resist pattern equal to 1 is X1, and in the lithography process of normal exposure using a light source of 193 nm, the solvent of the immersion exposure is subjected to selective exposure and post-exposure heating (PEB). [(X2 / X1) -1, when the sensitivity when forming a resist pattern in which the 130-nm line-and-space is 1: 1 by a simulated immersion lithography process including the step of contacting with the resist film is set to X2. Positive type which consists of silsesquioxane resin as a resin component characterized by the absolute value of] x100 is 8.0 or less. Composition.

The sixth aspect of the present invention is a resist pattern forming method using the positive resist composition of the fifth aspect, which is a method of forming a resist pattern comprising a step of immersion exposure. .

Further, the inventors of the present invention analyze the method of evaluating the aptitude of the resist film used in the resist pattern forming method including the immersion exposure step when the present fifth and sixth aspects are achieved, and the analysis is performed as follows. Based on the result, the resist composition and the resist pattern formation method using the composition were evaluated.

That is, in evaluating the resist pattern formation performance by immersion exposure, (i) the performance of the optical system by the immersion exposure method, (ii) the influence from the resist film on the immersion solvent, (iii) the deterioration of the resist film by the immersion solvent, It is judged that it is necessary if we can confirm three points of.

As for the performance of the optical system of (i), for example, assuming that the surface water-sensitive photographic photosensitive plate is immersed in water and irradiated with patterned light on the surface thereof, as is evident, the interface between the surface of water and the surface of water and the photosensitive plate In principle, there is no doubt that there is no problem in the rest if there is no light loss such as reflection. The loss of light propagation in this case can be easily solved by properizing the incident angle of exposure light. Therefore, even if the object to be exposed is a resist film, a photographic photosensitive plate, or an imaging screen, if they are inert to the immersion solvent, that is, they are not affected by the immersion solvent and do not affect the immersion solvent, the performance of the optical system is It can be thought that no change occurs. Therefore, there is no new confirmation test about this point.

The effect from the resist film on the immersion solvent of (ii) is specifically that the components of the resist film start to melt in the liquid, thereby changing the refractive index of the immersion solvent. If the refractive index of the immersion solvent is changed, the optical resolution of the pattern exposure is changed theoretically without experiment. In this regard, when the resist film is simply immersed in the immersion solvent, it is sufficient to be able to confirm that a component starts to melt, and that the composition of the immersion solvent changes or the refractive index changes. It does not develop until the resolution is confirmed.

On the contrary, if the resist film in the immersion solvent is irradiated with pattern light and developed to confirm resolution, whether the resolution of the immersion solvent can be confirmed, is it affected by the deterioration of the immersion solvent? This makes it impossible to distinguish whether it affects resolution or both.

As for the resolution deteriorated due to the deterioration of the resist film by the immersion solvent of (iii), the immersion solvent is sprayed onto the resist film by contacting it with a resist film, for example, like a shower, between selective exposure and post-exposure heating (PEB). Process, and then developed, and the resolution of the obtained resist pattern is inspected ”. In addition, in this evaluation method, an immersion solvent is immediately sprayed on the resist film, which becomes more severe as an immersion condition. Also in this regard, in the case of a test in which exposure is carried out in a fully immersed state, is it influenced by deterioration of the immersion solvent, deterioration by the immersion solvent of the resist composition, or is the resolution changed by both influences? Is not clear.

The above developments (ii) and (iii) are front and back developments, and can be grasped by confirming the degree of deterioration such as deterioration of the pattern shape and deterioration of sensitivity by the immersion solvent of the resist film. Therefore, verification only regarding the point of (iii) also includes verification related to the point of (ii).

Based on this analysis, the immersion exposure aptitude of the resist film formed of a new resist composition suitable for the immersion exposure process is described by "spraying an immersion solvent into the resist film, for example, like a shower, between selective exposure and post-exposure heating (PEB). The process of making it contact, it develops after that, and it confirmed by the evaluation test (henceforth "evaluation test 1") such as "testing the resolution of the obtained resist pattern".

Moreover, as another evaluation method which further advanced the evaluation test 1, the structure which exposes the sample to the actual immersion state by exposing the "pattern light of exposure to interference light by a prism, simulated the actual manufacturing process, and exposing (2) Evaluation test (hereinafter, referred to as "evaluation test 2") ", such as" Luminous flux interference exposure method ", was also conducted and confirmed.

Implement the invention  Best form for

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described.

<< silsesquioxane resin >>

The silsesquioxane resin of this invention has a structural unit represented by the said General Formula [1] and [2].

In addition, in this specification, a "structural unit" means the monomeric unit which comprises a polymer.

In general formula [1] and [2], R <^1> and R <^2> may be the same group or different group, and it is a linear, branched, or cyclic saturated aliphatic hydrocarbon group, respectively, and carbon number is the solubility to the resist solvent and From the viewpoint of controlling the molecular size, preferably 1 to 20, more preferably 5 to 12. In particular, the cyclic saturated aliphatic hydrocarbon group has a high transparency to the high energy light of the silsesquioxane resin obtained, a high glass transition point (Tg), and it is easy to control the generation of acid from an acid generator in PEB. It is preferable because it has advantages such as losing.

The cyclic saturated aliphatic hydrocarbon group may be a monocyclic group or a polycyclic group. Examples of the polycyclic group include groups in which two hydrogen atoms are removed from bicycloalkane, tricycloalkane, tetracycloalkane, and the like, and more specifically, adamantane, norbornane, isobornane, tricyclodecane and tetracyclo The group remove | excluding two hydrogen atoms from polycycloalkane, such as dodecane, etc. are mentioned.

As R <^1> and R <^2> , More specifically, following formula [3]-[8]:

[Tue 7]

And groups in which two hydrogen atoms are removed from an alicyclic compound selected from the group consisting of derivatives thereof. Here, the derivative means, in the alicyclic compound of formulas [3] to [8], at least one hydrogen atom is a lower alkyl group such as methyl group or ethyl group, for example, an alkyl group having 1 to 5 carbon atoms, an oxygen atom, fluorine, Mean substituted by groups, such as halogen atoms, such as chlorine and a bromine.

Especially, the group which removed two hydrogen atoms from the alicyclic compound chosen from the group of Formula [3]-[8] is preferable at the point which is high in transparency and is easy to obtain industrially.

R ³ is an acid dissociable, dissolution inhibiting group consisting of a hydrocarbon group containing an aliphatic monocyclic or polycyclic group. The acid dissociable, dissolution inhibiting group has an alkali dissolution inhibiting property in which the entire silsesquioxane resin before exposure is alkali insoluble, and is dissociated by the action of an acid generated from an acid generator after exposure, so that the entire silsesquioxane resin Is a group that changes alkali solubility.

Since the silsesquioxane resin (A1) of the present invention has an acid dissociable, dissolution inhibiting group composed of a hydrocarbon group having a large volume and containing an aliphatic monocyclic or polycyclic group such as, for example, Formulas [9] to [13] described later. As compared to conventional acid dissociable, dissolution inhibiting groups which do not have ventilation, such as chained alkoxyalkyl groups such as 1-ethoxyethyl groups, cyclic ether groups such as tetrahydropyranyl groups, and branched tertiary alkyl groups such as tert-butyl groups, When used as the base resin of the positive resist composition, the dissolution inhibiting group after dissociation is difficult to gasify and degassing phenomenon is prevented.

The carbon number of R ³ is difficult to gasify when dissociated, and is preferably 7 to 15, more preferably 9 to 13, from the viewpoint of solubility in an appropriate resist solvent and solubility in a developing solution.

As an acid dissociable, dissolution inhibiting group, many are proposed according to the light source to be used, for example in resin for resist compositions of ArF excimer laser, as long as it is an acid dissociable, dissolution inhibiting group which consists of a hydrocarbon group containing an aliphatic monocyclic or polycyclic group. It can select from the appropriately, and can use. In general, it is widely known to form a cyclic tertiary alkyl ester with a carboxyl group of (meth) acrylic acid.

In particular, it is preferable that it is an acid dissociable, dissolution inhibiting group containing an aliphatic polycyclic group. As the aliphatic polycyclic group, ArF resists can be appropriately selected and used among many proposed ones. For example, the aliphatic polycyclic group includes a group obtained by removing one hydrogen atom from bicycloalkane, tricycloalkane, tetracycloalkane and the like, and more specifically, adamantane, norbornane, isobornane and tri The group remove | excluding one hydrogen atom from polycycloalkane, such as cyclodecane and tetracyclo dodecane, etc. are mentioned.

More specifically, the following formulas [9] to [13]:

[Tue 8]

The group chosen from the group which consists of these is mentioned. In particular, the silsesquioxane resin having a 2-methyl-2-adamantyl group represented by the formula [11] and / or a 2-ethyl-2-adamantyl group represented by the formula [12] is degassed. It is preferable because it is difficult and excellent in resist characteristics such as resolution and heat resistance.

R ⁴ is a hydrogen atom or a linear, branched or cyclic alkyl group. The carbon number of the alkyl group is preferably a lower alkyl group of 1 to 10, more preferably 1 to 4 from the viewpoint of solubility in a resist solvent.

More specifically, as the alkyl group, methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, cyclopentyl group, cyclohexyl group, 2-ethylhexyl group, n-octyl group Etc. can be illustrated.

R ⁴ is appropriately selected depending on the desired alkali solubility of the silsesquioxane resin. R ⁴ is the higher the alkali solubility in the case of a hydrogen atom. When alkali solubility becomes high, there exists an advantage that it can be highly sensitive.

On the other hand, the larger the carbon number of the alkyl group and the larger the volume, the lower the alkali solubility of the silsesquioxane resin. When alkali solubility becomes low, resistance to alkali developing solution improves, and the exposure margin at the time of forming a resist pattern using this silsesquioxane resin improves, and the dimensional variation accompanying exposure becomes small. In addition, since development unevenness is eliminated, the roughness of the edge portion of the formed resist pattern is also improved.

X is a linear, branched or cyclic alkyl group in which at least one hydrogen atom is substituted with a fluorine atom, and is preferably linear. Carbon number of an alkyl group is 1-8, Preferably it is 1-4 lower alkyl groups from a glass transition point (Tg) of a silsesquioxane resin, and the solubility to a resist solvent.

The larger the number of hydrogen atoms substituted with fluorine atoms, the higher the transparency to high energy light and electron beams of 200 nm or less is preferable. Most preferably, all hydrogen atoms are perfluoroalkyl groups substituted with fluorine atoms.

In General Formula [1] and [2], each X may be same or different, respectively. That is, the plurality of Xs are each independently.

m is an integer of 1-3, Preferably it is 1 because it is easy to dissociate an acid dissociable, dissolution inhibiting group.

As the silsesquioxane resin of the present invention, more specifically, the following general formulas [14] and [15]:

[Tue 9]

The silsesquioxane resin which has a structural unit represented by can be illustrated.

In the formula, R ¹ and R ² are as described above. R ⁵ is a lower alkyl group, preferably an alkyl group having 1 to 5 carbon atoms, more preferably a methyl group or an ethyl group. n is 1-8, Preferably it is an integer of 1-2.

That is, in the general formula [14] and [15] of the general formula [1] and [2], a group that is R ³ is represented by such as formula [11] or the formula [12], wherein R ⁴ is a hydrogen atom, X is an alkyl group in which all hydrogen atoms are substituted with fluorine atoms, and m = 1. R ³ is more preferably the case of formula [11].

Of all the structural units constituting the silsesquioxane resin of the present invention, the ratio of the structural units represented by the general formulas [1] and [2] is 30 to 100 mol%, preferably 60 to 100%. That is, you may contain structural units other than the structural unit represented by General formula [1] or [2] in 40 mol% or less in silsesquioxane resin. Any structural unit other than the structural unit represented by this general formula [1] or [2] is demonstrated later.

Moreover, with respect to the sum total of the structural units represented by General Formula [1] and [2], the ratio of the structural unit represented by General Formula [1] becomes like this. Preferably it is 5-70 mol%, More preferably, it is 10-40 Mol%. Preferably the ratio of the structural unit represented by General formula [2] is 30-95 mol%, More preferably, it is 60-90 mol%.

By carrying out the ratio of the structural unit represented by General formula [1] in the said range, the ratio of an acid dissociable, dissolution inhibiting group is spontaneously determined, and the change of alkali solubility before and after exposure of a silsesquioxane resin changes the positive resist composition. It becomes preferable as a base resin.

The silsesquioxane resin of this invention is a structural unit other than the structural unit represented by general formula [1] and [2] as said arbitrary component in the range which does not impair the effect of this invention, for example ArF excimer Alkylsilsesquioxane which has lower alkyl groups, such as a methyl group, an ethyl group, a propyl group, and a butyl group, what is used for the silsesquioxane resin for resist compositions of a laser, for example represented by following General formula [17]. A unit etc. can be illustrated.

[Tue 10]

[Wherein, R 'represents a linear or branched lower alkyl group, preferably a C1-5 lower alkyl group.]

When using the structural unit represented by general formula [17], the ratio of the structural unit represented by general formula [1] with respect to the sum total of the structural units represented by general formula [1], [2], and [17] Is 5 to 30 mol%, preferably 8 to 20 mol%. The proportion of the structural unit represented by the general formula [2] is 40 to 80 mol%, preferably 50 to 70 mol%, and the proportion of the structural unit represented by the general formula [17] is 1 to 40 mol%, preferably It can be used in the range of 5 to 35 mol%.

Although the mass average molecular weight (Mw) (polystyrene conversion by gel permeation chromatography, the same below) of the silsesquioxane resin of this invention is not specifically limited, Preferably it is 2000-15000, More preferably, it is 3000-8000. . When larger than this range, the solubility with respect to a resist solvent may worsen, and when small, there exists a possibility that a cross-sectional shape of a resist pattern may worsen.

In addition, Mw / number average molecular weight (Mn) is although it does not specifically limit, Preferably it is 1.0-6.0, More preferably, it is 1.1-2.5. When larger than this range, there exists a possibility that a resolution and a pattern shape may deteriorate.

The silsesquioxane resin of this invention can be manufactured by the method generally used for manufacture of a random polymer, For example, it can manufacture as follows.

First, a polymer solution containing a polymer containing a polymer having silsesquioxane in the basic skeleton by dehydrating condensation alone or in a mixture of two or more kinds of Si-containing monomers for inducing the structural unit represented by Formula [2] under an acid catalyst. Get To this polymer solution, Br- (CH ₂ ) _m COOR ³ in an amount of 5 to 70 mol% of the Si-containing monomer is dissolved in an organic solvent such as tetrahydrofuran and added dropwise, and -OR ⁴ is -O- The addition reaction is performed with (CH ₂ ) _m COOR ³ .

In addition, when it contains the structural unit represented by Formula [17], using the Si containing monomer which guides the structural unit represented by Formula [2], and the Si containing monomer which guides the structural unit represented by Formula [17], It can synthesize | combine similarly to the above.

As described above, the silsesquioxane resin of the present invention is useful for preventing degassing after exposure when forming a resist pattern.

In addition, since the silsesquioxane resin of this invention is a polymer which has the silsesquioxane comprised by the structural unit represented by Formula [1] and [2] and, optionally, Formula [17] in a basic skeleton, it is 200 nm. High transparency to the following high energy light and an electron beam is high. Therefore, the positive resist composition containing the silsesquioxane resin of the present invention is useful in lithography using a shorter wavelength light source than, for example, an ArF excimer laser. Particularly, even in a single layer process, the line width is 150 nm or less, preferably 120 nm. This can form a fine resist pattern. Moreover, it is useful also in the process of forming the fine resist pattern of 120 nm or less, Preferably it is 100 nm or less by using it as the upper layer of the 2-layer resist laminated body mentioned later.

<< positive resist composition >>

-(A) component

The positive resist composition of the present invention is a positive resist composition containing a resin component (A) in which alkali solubility is increased by the action of an acid and an acid generator component (B) which generates an acid upon exposure, wherein ( A) component contains the silsesquioxane resin (henceforth a silsesquioxane resin (A1)) of this invention mentioned above, It is characterized by the above-mentioned.

By using a silsesquioxane resin (A1) for (A) component, the degassing at the time of forming a resist pattern using the positive resist composition containing this silsesquioxane resin (A1) can be prevented. have. Moreover, this positive resist composition also has high transparency to 200 nm or less of high energy light and an electron beam, and the pattern of high resolution is obtained.

Although the silsesquioxane resin (A1) in (A) component can be used independently, mixed resin with resin other than (A1) may be sufficient. The ratio of (A1) in the mixed resin is preferably 50 to 95% by mass, more preferably 70 to 90% by mass.

By making the ratio of silsesquioxane resin (A1) into the said range, it is excellent in the prevention effect of degassing phenomenon, and when it is set as a two-layered resist laminated body, it is excellent as a masking material when dry-etching an underlying resist layer.

As the resin component (A2) other than (A1), any resin generally used as the base resin of the chemically amplified resist composition can be used depending on the light source used at the time of forming the resist pattern.

For example, when using an ArF excimer laser, (a1) mixed resin with the resin component (A2) containing the structural unit derived from the (meth) acrylic acid ester which has an acid dissociable, dissolution inhibiting group, It is preferable at the point which improves heat resistance of resin and is excellent in high resolution.

As this (A2) resin, it has a structural unit guide | induced from (meth) acrylic acid ester which has an acid dissociable, dissolution inhibiting group, and contains the structural unit guide | induced from other (meth) acrylic acid ester other than (a1), Resin containing 80 mol% or more, preferably 90 mol% or more (100 mol% is most preferable) of the structural unit derived from an acrylic acid ester is preferable.

"(Meth) acrylic acid" represents one or both of methacrylic acid and acrylic acid. "(Meth) acrylate" represents one or both of methacrylate and acrylate.

In addition, in order to satisfy | fill resolution, dry etching resistance, and the shape of a fine pattern, (A2) resin is a monomer unit which has several different functions other than a (a1) unit, for example, by the combination of the following structural units. It is composed.

Structural units derived from (meth) acrylic acid esters having lactone units (hereinafter referred to as (a2) or (a2) units),

A structural unit derived from (meth) acrylic acid ester having an alcoholic hydroxyl group-containing polycyclic group (hereinafter referred to as (a3) or (a3) unit),

A structural unit containing a polycyclic group which is different from any of the acid dissociable, dissolution inhibiting group of the (a1) unit, the lactone unit of the (a2) unit, and the alcoholic hydroxyl group-containing polycyclic group of the (a3) unit (hereinafter, (a4) or (a4) units).

(a2), (a3) and / or (a4) can be combined suitably according to the characteristic etc. which are requested | required.

Preferably, the component (A2) contains at least one unit selected from (a1), (a2), (a3) and (a4), whereby the resolution and the resist pattern shape are improved. Moreover, you may use multiple types together different unit with respect to each among (a1)-(a4) units.

The component (A2) is 10 to 85 mol% of the structural unit derived from methacrylic acid ester with respect to the total number of moles of the structural unit derived from methacrylic acid ester and the structural unit derived from acrylic acid ester. It is preferable to contain 20-80 mol% and 15-90 mol%, Preferably it is 20-80 mol% of the structural unit derived from acrylic acid ester.

Next, the above units (a1) to (a4) will be described in detail.

[(a1) units]

The unit (a1) is a structural unit derived from (meth) acrylic acid ester having an acid dissociable, dissolution inhibiting group.

The acid dissociable, dissolution inhibiting group in (a1) has an alkali dissolution inhibiting property that renders the entire component (A2) insoluble in alkali before exposure, and dissociates by the action of the acid generated from the component (B) after exposure. As long as this whole (A2) component is changed to alkali solubility, it can be used, without particular limitation. Generally, the carboxyl group of (meth) acrylic acid, the group which forms a cyclic or linear tertiary alkylester, tertiary alkoxycarbonyl group, or a linear alkoxyalkyl group are known widely.

As the acid dissociable inhibitor in (a1), for example, an acid dissociable dissolution inhibiting group containing an aliphatic polycyclic group can be preferably used.

Examples of the polycyclic group include groups in which one hydrogen element is removed from a bicycloalkane, tricycloalkane, tetracycloalkane or the like which may or may not be substituted with a fluorine atom or a fluorinated alkyl group. Specifically, the group remove | excluding one hydrogen atom from polycyclo alkanes, such as adamantane, norbornane, isobornane, tricyclodecane, and tetracyclo dodecane, is mentioned. Such polycyclic groups can be appropriately selected and used among many proposed ones in ArF resists. Among these, adamantyl group, norbornyl group, and tetracyclododecanyl group are industrially preferable.

Preferred monomer units as (a1) are shown in the following [formula 11] to [formula 19].

[Tue 11]

(Wherein R is a hydrogen atom or a methyl group and R ²¹ is a lower alkyl group)

[Tue 12]

(Wherein R is a hydrogen atom or a methyl group, R ²² and R ²³ are each independently a lower alkyl group.)

[Tue 13]

(Wherein R is a hydrogen atom or a methyl group and R ²⁴ is a tertiary alkyl group)

[Tue 14]

(Wherein R is a hydrogen atom or a methyl group)

[Tue 15]

(Wherein R is a hydrogen atom or a methyl group and R ²⁵ is a methyl group)

[Tue 16]

(Wherein R is a hydrogen atom or a methyl group and R ²⁶ is a lower alkyl group)

[Tue 17]

(Wherein R is a hydrogen atom or a methyl group)

[Tue 18]

(Wherein R is a hydrogen atom or a methyl group)

[Tue 19]

(Wherein R is a hydrogen atom or a methyl group and R ²⁷ is a lower alkyl group)

The R ²¹ to R ²³ and R ²⁶ to R ²⁷ each preferably have a lower linear or branched alkyl group having 1 to 5 carbon atoms, and include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, tert-butyl group, pentyl group, isopentyl group, neopentyl group and the like. Industrially, a methyl group or an ethyl group is preferable.

In addition, R ²⁴ is a tertiary alkyl group such as tert-butyl group or tert-amyl group, and industrially preferred to be tert-butyl group.

As the unit (a1), the structural units represented by the general formulas (I), (II) and (III), among the above, can form a pattern having high transparency, high resolution and excellent dry etching resistance. Therefore, it is more preferable.

[(a2) units]

Since the unit (a2) has a lactone unit, it is effective in order to improve hydrophilicity with the developing solution.

The unit (a2) in the present invention may be a lactone unit and copolymerizable with other structural units of the component (A).

For example, as a monocyclic lactone unit, the group etc. which removed one hydrogen atom from (gamma) -butyrolactone are mentioned. Moreover, as a polycyclic lactone unit, the group etc. which removed one hydrogen atom from lactone containing polycycloalkane are mentioned. At this time, in the lactone unit, the ring containing the -O-C (O)-structure is counted as the first ring. Therefore, in the case where the ring structure is only a ring containing an —O—C (O) — structure, the ring structure is referred to as a polycyclic group irrespective of its structure when having a further ring structure.

Preferred monomer units as (a2) are shown in the following general formulas [Formula 20] to [Formula 22].

[Tue 20]

Wherein R is a hydrogen atom or a methyl group

[Tue 21]

Wherein R is a hydrogen atom or a methyl group

[Tue 22]

Wherein R is a hydrogen atom or a methyl group

Among these, (gamma) -butyrolactone ester of (meth) acrylic acid which has an ester bond to (alpha) carbon as shown in [Chem 22], or norbornane lactone ester like [Chem 20] and [Chem 21] is especially It is easy to obtain industrially, and it is preferable.

[(a3) units]

The unit (a3) is a structural unit derived from (meth) acrylic acid ester having an alcoholic hydroxyl group-containing polycyclic group. Since the hydroxyl group in the said alcoholic hydroxyl group containing polycyclic group is a polar group, by using this, hydrophilicity with the developing solution of the whole (A2) component becomes high and alkali solubility in an exposure part improves. Therefore, when (A2) component has (a3), since resolution improves, it is preferable.

And as a polycyclic group in (a3), it can select suitably from the aliphatic polycyclic group similar to what was illustrated by description of said (a1), and can be used.

Although the alcoholic hydroxyl group containing polycyclic group in (a3) is not specifically limited, For example, a hydroxyl group containing adamantyl group etc. are used preferably.

Moreover, since this hydroxyl-containing adamantyl group is represented by following General formula (IV), since it has an effect which raises dry-etch resistance and raises the perpendicularity of a pattern cross-sectional shape, it is preferable.

[Tue 23]

(Wherein l is an integer of 1 to 3)

The unit (a3) may be one having an alcoholic hydroxyl group-containing polycyclic group as described above and copolymerizable with another structural unit of the component (A2).

Specifically, the structural unit represented by the following general formula (V) is preferable.

[Tue 24]

(Wherein R is a hydrogen atom or a methyl group)

[(a4) units]

In the unit (a4), "a different from any of said acid dissociable, dissolution inhibiting group, said lactone unit, and said alcoholic hydroxyl group-containing polycyclic group" is a polycyclic group, in the component (A2), wherein the The polycyclic group is a polycyclic group which does not overlap with any of the acid dissociable, dissolution inhibiting group of (a1) units, lactone units of (a2) units, and alcoholic hydroxyl group-containing polycyclic groups of (a3) units, a4) means that the acid dissociable, dissolution inhibiting group of the unit (a1) constituting the component (A2), the lactone unit of the unit (a2), and the alcoholic hydroxyl group-containing polycyclic group of the unit (a3) are not maintained. Doing.

The polycyclic group in (a4) unit should just be selected so that it may not overlap with the structural unit used as said (a1)-(a3) unit in one (A2) component, It does not specifically limit. For example, as the polycyclic group in the unit (a4), the same aliphatic polycyclic group as exemplified as the unit (a1) can be used, and a large number of conventionally known ones can be used as the ArF positive resist material.

Especially at least 1 sort (s) chosen from a tricyclo decanyl group, an adamantyl group, and a tetracyclo dodecanyl group, it is preferable at the point of industrial availability, and the like.

What is necessary is just to have a polycyclic group as above-mentioned as a unit (a4), and to be copolymerizable with the other structural unit of (A) component.

Preferable examples of (a4) are shown in the following [Tue 25] to [Tue 27].

[Tue 25]

Wherein R is a hydrogen atom or a methyl group

[Tue 26]

Wherein R is a hydrogen atom or a methyl group

[Tue 27]

Wherein R is a hydrogen atom or a methyl group

In the positive resist composition of the present invention, the composition of the component (A2) is 20 to 60 mol%, preferably 30 to 50 mol, based on the total of the structural units constituting the component (A2). % Is preferable because it is excellent in resolution.

Moreover, with respect to the sum total of the structural units which comprise (A2) component, when (a2) unit is 20-60 mol%, Preferably it is 30-50 mol%, it is preferable because it is excellent in resolution.

In the case of using the unit (a3), the resist pattern shape is preferably excellent in the range of 5 to 50 mol%, preferably 10 to 40 mol%, based on the total of the structural units constituting the component (A2).

In the case of using the unit (a4), the semi-dense pattern may be formed from an isolated pattern of 1 to 30 mol%, preferably 5 to 20 mol%, based on the total of the structural units constituting the component (A2). It is preferable because of its excellent resolution.

Units (a1) and at least one unit selected from (a2), (a3) and (a4) units can be appropriately combined according to the purpose, but are three-membered units of (a1) units and (a2) and (a3) units. A polymer is preferable because it is excellent in resist pattern shape, exposure margin, heat resistance, and resolution. The content of each structural unit (a1) to (a3) at that time is preferably 20 to 60 mol% of (a1), 20 to 60 mol% of (a2), and 5 to 50 mol% of (a3).

In addition, the mass average molecular weight of the resin component (A2) in this invention is although it does not specifically limit, Preferably it is 5000-30000, More preferably, it is 8000-20000. When larger than this range, the solubility to a resist solvent may worsen, and when it is small, there exists a possibility that dry etching resistance and a resist pattern cross-sectional shape may worsen.

The resin component (A2) in this invention is azobisisobutyronitrile (AIBN) of the monomer corresponded to each structural unit of (a1) and (a2), (a3) and / or (a4) as needed, and (a1). It can be manufactured easily by copolymerizing by known radical polymerization using a radical polymerization initiator such as).

-(B) component

As the component (B), any of those known as acid generators in conventional chemically amplified resists can be appropriately selected and used.

Specific examples of the component (B) include diphenyl iodonium trifluoromethanesulfonate, (4-methoxyphenyl) phenyl iodonium trifluoromethanesulfonate, and bis (p-tert-butylphenyl) iodonium tri Fluoromethanesulfonate, triphenylsulfonium trifluoromethanesulfonate, (4-methoxyphenyl) diphenylsulfoniumtrifluoromethanesulfonate, (4-methylphenyl) diphenylsulfonium nonafluorobutanesulfonate , (p-tert-butylphenyl) diphenylsulfonium trifluoromethanesulfonate, diphenyl iodonium nonafluorobutanesulfonate, bis (p-tert-butylphenyl) iodonium nonafluorobutanesulfonate , Triphenylsulfonium nonafluorobutanesulfonate, (4-trifluoromethylphenyl) diphenylsulfonium trifluoromethanesulfonate, (4-trifluoromethylphenyl) diphenylsulfonium nonafluorobutanesulfonate, Tri (p-tert-butylphenyl) sulfoniumtrifluoromethane Po and the like onium salts such as carbonate.

Among the onium salts, triphenylsulfonium salts are preferably used because they are difficult to decompose and hardly generate organic gases. The compounding quantity of the triphenylsulfonium salt is preferably 50 to 100 mol%, more preferably 70 to 100 mol%, most preferably 100 mol% with respect to the total of the component (B).

In addition, among the onium salts, the iodonium salt may be the cause of the organic gas containing iodine.

In addition, among the triphenylsulfonium salts, the triphenylsulfonium salt in which the perfluoroalkylsulfonate ion represented by following General formula [16] as an anion can be highly sensitive, and it is used preferably.

[Tue 28]

[Wherein, R ¹¹ , R ¹² and R ¹³ are each independently a hydrogen atom, a lower alkyl group having 1 to 8 carbon atoms, preferably 1 to 4 carbon atoms, or a halogen atom such as chlorine, fluorine or bromine; p is 1-12, Preferably it is 1-8, More preferably, it is an integer of 1-4.]

(B) A component may be used independently and may be used in combination of 2 or more type. The compounding quantity is 0.5-30 mass parts with respect to 100 mass parts of (A) component, Preferably it is 1-10 mass parts. If it is less than 0.5 mass part, pattern formation will not fully be performed, and if it exceeds 30 mass parts, a uniform solution will be hard to be obtained and it may become a cause that storage stability falls.

The positive resist composition of the present invention is prepared by dissolving the component (A), the component (B), and optional components described later in an organic solvent.

What is necessary is just to be what can melt | dissolve the said (A) component and the said (B) component, and to make it a uniform solution as an organic solvent, and selects arbitrary 1 type (s) or 2 or more types suitably from what is known as a solvent of the conventional chemically amplified resist Can be used.

In the photoresist composition according to the present invention, the content of the organic solvent component is appropriately set in accordance with the resist film pressure in a range where the solid content concentration of the resist composition is 3 to 30% by mass.

For example, ketones such as acetone, methyl ethyl ketone, cyclohexanone, methyl isoamyl ketone, 2-heptanone, ethylene glycol, ethylene glycol monoacetate, diethylene glycol, diethylene glycol monoacetate, propylene glycol, Polyhydric alcohols such as monomethyl ether, monoethyl ether, monopropyl ether, monobutyl ether or monophenyl ether of propylene glycol monoacetate, dipropylene glycol or dipropylene glycol monoacetate and derivatives thereof, and cyclic compounds such as dioxane And ethers such as methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate and ethyl ethoxypropionate. These organic solvents may be used independently and may be used as 2 or more types of mixed solvents.

In addition, in the positive resist composition of the present invention, in order to improve the resist pattern shape, stability over time, etc., as a quencher, a known amine, preferably a secondary lower aliphatic amine or tertiary lower Aliphatic amine, organic acids, such as organic carboxylic acid, the phosphorus oxo acid, or its derivative (s) can be contained.

Lower aliphatic amines herein refer to amines of alkyl or alkyl alcohols having 5 or less carbon atoms. Examples of the secondary and tertiary amines include trimethylamine, diethylamine, triethylamine, di-n-propylamine, and tri-n. -Propylamine, tripentylamine, diethanolamine, triethanolamine and the like can be mentioned, but alkanolamines such as triethanolamine are particularly preferred. These may be used independently and may be used in combination of 2 or more type. These amines are normally used in 0.01-2.0 mass% with respect to (A) component. As organic carboxylic acid, malonic acid, citric acid, malic acid, succinic acid, benzoic acid, salicylic acid, etc. are preferable, for example.

Examples of phosphorus oxo acids or derivatives thereof include derivatives such as phosphoric acid or their esters such as phosphoric acid, phosphoric acid di-n-butyl ester and phosphoric acid diphenyl ester, phosphonic acid, phosphonic acid dimethyl ester, phosphonic acid-di-n-butyl ester and phenyl Derivatives such as phosphonic acids such as phosphonic acid, phosphonic acid diphenyl ester, phosphonic acid dibenzyl ester and esters thereof, and derivatives such as phosphinic acid such as phosphinic acid and phenylphosphinic acid and esters thereof, among others Phonic acid is preferred.

An organic acid is used in the ratio of 0.01-5.0 mass parts per 100 mass parts of (A) component. These may be used independently and may be used in combination of 2 or more type. These organic acids are preferably used in the range below equimolar with the said amine.

The positive type resist composition of the present invention may further contain miscible additives as desired, for example, additional resins for improving the performance of resist films, surfactants for improving applicability, dissolution inhibitors, plasticizers, stabilizers, coloring agents. And an antihalation agent can be added.

By using the positive resist composition obtained by such a structure, when forming a resist pattern, the degassing phenomenon after exposure can be reduced. Moreover, high transparency with respect to high energy light and an electron beam of 200 nm or less is also high, and it is high resolution.

<< resist laminated body >>

The resist laminate of the present invention is a laminate of a lower resist layer which is insoluble in an alkaline developer and dry-etchable on a support, and an upper resist layer made of the positive resist composition of the present invention.

It does not specifically limit as a support body, A conventionally well-known thing can be used, For example, the board | substrate for electronic components, the thing in which predetermined wiring pattern was formed, etc. can be illustrated.

As a board | substrate, the board | substrate made from metals, such as a silicon wafer, copper, chromium, iron, aluminum, a glass substrate, etc. are mentioned, for example.

As a material of a wiring pattern, copper, aluminum, nickel, gold, etc. can be used, for example.

The lower resist layer is an organic film that is insoluble in the alkaline developer used during development after exposure and can be etched by a conventional dry etching method.

By using such a lower resist layer, only the upper resist layer is exposed and alkali-developed by ordinary photolithography to form a resist pattern, and then the lower resist layer is dry-etched by using the resist pattern as a mask. The resist pattern of the upper resist layer is transferred. As a result, a resist pattern having a high aspect ratio can be formed without causing a pattern collapse of the resist pattern.

Although the resist material for forming a lower resist layer is called resist, what is generally used as a base material in manufacture of a semiconductor element or a liquid crystal display element is used instead of requiring the same photosensitivity as an upper layer resist.

In addition, since it is necessary to transfer the upper resist pattern to the lower resist, the lower resist layer is preferably a material which can be etched by oxygen plasma.

Such a material is composed of a novolak resin, an acrylic resin, and a soluble polyimide because it is easy to etch by oxygen plasma and has a high resistance to fluorocarbon gases used for etching silicon substrates and the like in a later step. It is preferably used to have at least one kind selected from the group as a main component.

Among these, novolak resins and acrylic resins having alicyclic moieties or aromatic rings in the side chains are inexpensive and widely used, and are preferably used because they are excellent in dry etching resistance in subsequent processes.

As a novolak resin, what is generally used for a positive resist composition can be used, The positive resist for i line | wire and g line containing a novolak resin as a main component can also be used.

Novolac resin is resin obtained by addition condensation of the aromatic compound (henceforth simply "phenol") and aldehydes which have a phenolic hydroxyl group, for example under an acidic catalyst.

Examples of the phenols include phenol, o-cresol, m-cresol, p-cresol, o-ethylphenol, m-ethylphenol, p-ethylphenol, o-butylphenol, m-butylphenol, p-butylphenol, 2 , 3-xylenol, 2, 4-xylenol, 2,5-xylenol, 2,6-xylenol, 3,4-xylenol, 3,5-xylenol, 2,3 , 5-trimethylphenol, 3,4,5-trimethylphenol, p-phenylphenol, resorcinol, hydroquinone, hydroquinone monomethyl ether, pyrogallol, phloroglycinol, hydroxydiphenyl, bisphenol A, gallic acid , Gallic acid ester, α-naphthol, p-naphthol and the like.

Examples of the aldehydes include formaldehyde, furfural, benzaldehyde, nitrobenzaldehyde, acetaldehyde and the like.

Although the catalyst at the time of addition condensation reaction is not specifically limited, For example, hydrochloric acid, nitric acid, sulfuric acid, formic acid, oxalic acid, acetic acid etc. are used for an acid catalyst.

It is preferable that the said novolak resin exists in the range of 3000-10000, Preferably 6000-9000, More preferably, 7000-8000. When the mass average molecular weight is less than 3000, the resistance to the alkaline developer tends to decrease, and when the mass average molecular weight exceeds 10000, the dry etching tends to be difficult, which is not preferable.

What is marketed can be used for the novolak resin which can be used in this invention.

As an acrylic resin, what is generally used for a positive resist composition can be used, For example, acrylic resin containing the structural unit derived from the polymeric compound which has an ether bond, and the structural unit derived from the polymeric compound which has a carboxyl group. Can be mentioned.

As a polymeric compound which has an ether bond, 2-methoxyethyl (meth) acrylate, methoxy triethylene glycol (meth) acrylate, 3-methoxybutyl (meth) acrylate, ethylcarbitol (meth) acrylate, (Meth) acrylic acid derivatives having ether bonds and ester bonds such as phenoxy polyethylene glycol (meth) acrylate, methoxy polypropylene glycol (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, and the like can be exemplified. . These compounds can be used individually or in combination of 2 or more types.

As a polymeric compound which has a carboxyl group, Monocarboxylic acids, such as acrylic acid, methacrylic acid, a crotonic acid; Dicarboxylic acids such as maleic acid, fumaric acid and itaconic acid; Having carboxyl groups and ester bonds, such as 2-methacryloyloxyethyl succinic acid, 2-methacryloyloxyethyl maleic acid, 2-methacryloyloxyethyl phthalic acid, and 2-methacryloyloxyethyl hexahydrophthalic acid A compound etc. can be illustrated, Preferably it is acrylic acid and methacrylic acid. These compounds can be used individually or in combination of 2 or more types.

Soluble polyimide is a polyimide which can be made into a liquid by the organic solvent as described above.

In the resist laminate of the present invention, the thicknesses of the upper resist layer and the lower resist layer are total, preferably 15 µm, from the viewpoint of the balance of throughput in consideration of the desired aspect ratio and the time required for dry etching of the lower resist layer. Hereinafter, More preferably, it is 0.1-5 micrometers.

The thickness of the upper resist layer is preferably 50 nm to 1 m, more preferably 70 to 250 nm. By setting the thickness of the upper resist layer within this range, there is an effect that a resist pattern can be formed at high resolution, and sufficient resistance to dry etching is obtained.

The thickness of the lower resist layer is preferably 100 nm to 14 μm, more preferably 200 to 500 nm. By setting the thickness of the lower resist layer within this range, there is an effect that a resist pattern having a high aspect ratio can be formed, and sufficient etching resistance can be ensured during substrate etching.

The resist laminate of the present invention also includes a laminate in which a resist pattern is formed in an upper resist layer and a lower resist layer, and a laminate in which no resist is formed.

<< resist pattern formation method >>

The resist pattern formation method of this invention can be performed as follows, for example.

First, a resist composition or a resin solution for forming a lower resist layer is applied on a substrate such as a silicon wafer with a spinner, preferably for 200 to 300 ° C for 30 to 300 seconds, preferably for 60 to 180 seconds. Baking under heating conditions to form a lower resist layer.

In addition, an organic or inorganic antireflection film may be formed between the lower resist layer and the upper resist layer.

Next, the positive resist composition of this invention is apply | coated with a spinner etc. on a lower resist layer, and prebaking is performed for 40 to 120 second, Preferably it is 60 to 90 second, under the temperature conditions of 80-150 degreeC, An upper resist layer is formed to obtain a resist laminate of the present invention.

The resist laminate is selectively exposed to ArF excimer laser light through a desired mask pattern, for example, by an ArF exposure apparatus or the like, and then PEB (post-exposure heating) is subjected to a temperature of 80 to 150 ° C under 40 conditions. 120 seconds, Preferably it is 60 to 90 seconds.

Next, this is developed using alkaline developing solution, for example, 0.05-10 mass%, Preferably 0.05-3 mass% tetramethylammonium hydroxide aqueous solution. In this way, the resist pattern (I) which is faithful to a mask pattern can be formed in the upper resist layer.

The light source used for exposure is particularly useful for ArF excimer lasers, but longer wavelength KrF excimer lasers and shorter wavelength F ₂ excimer lasers, EUV (extreme ultraviolet rays), VUV (vacuum ultraviolet rays), electron beams, X-rays and soft X-rays It is also effective against radiation such as.

Next, using the obtained resist pattern (I) as a mask pattern, dry etching of the lower resist layer is performed to form the resist pattern (II) in the lower resist layer.

As a dry etching method, Chemical etching, such as downflow etching and chemical dry etching; Physical etching such as sputter etching and ion beam etching; Known methods such as chemical and physical etching such as RIE (reactive ion etching) can be used.

The most common dry etching is a parallel plate RIE. In this method, first, a resist laminate is placed in a chamber of an RIE apparatus and a necessary etching gas is introduced. When a high frequency voltage is applied to the holder of the resist stack placed in parallel with the upper electrode in the chamber, the etching gas is plasmalized. In the plasma, charged particles such as positive and negative ions and electrons, neutral active species, and the like exist. When these etching species are adsorbed to the lower resist layer, a chemical reaction occurs, and the reaction product leaves the surface and is exhausted to the outside to proceed with etching.

Examples of the etching gas include oxygen and sulfur dioxide, but etching using oxygen plasma has high resolution, and the silsesquioxane resin (A1) of the present invention has high etching resistance to oxygen plasma, and is generally used. For example, oxygen is preferably used.

According to the resist pattern formation method of this invention, when forming a resist pattern, the degassing phenomenon after exposure hardly arises. Moreover, the shape of the resist pattern obtained in this way is a high aspect ratio, there is no pattern collapse, and it is a favorable thing with high verticality. In addition, the resist pattern forming method of the present invention can form a resist pattern having a fine width of 100 nm, preferably 65 nm or less, using a high energy light or an electron beam of 200 nm or less, for example, an ArF excimer laser.

<< Positive resist composition containing silsesquioxane resin, Resist pattern formation method using this positive resist composition >>

The positive resist composition of the fifth aspect of the present invention may be, for example, immersion lithography (immersion exposure or liquid immersion exposure described in the above-described non-patent document 1, non-patent document 2, non-patent document 3, etc.). Can be used suitably. In this method, at the time of exposure, the gap portion between the lens, which was conventionally an inert gas such as air or nitrogen, and the resist layer on the wafer, has a refractive index greater than that of air, for example, a solvent such as pure water or a fluorine-based inert liquid. Filled with. It is known that by using such a solvent, even when a light source of the same exposure wavelength is used, high resolution is achieved and a focal depth is not lowered as in the case of using a shorter light source or a high Na lens.

The use of such immersion lithography has attracted much attention as it is possible to realize the formation of a resist pattern which is low in cost, excellent in high resolution and excellent in depth of focus by using a lens currently mounted in an apparatus.

That is, the positive resist composition of the fifth aspect of the present invention is a resist composition used in a resist pattern formation method including a step of immersion exposure, and is made of 130 nm by a lithography process of normal exposure using a light source having a wavelength of 193 nm. In the lithography process of normal exposure using the 193 nm light source, the sensitivity when forming a resist pattern with a line and space of 1 to 1 is X1, and the immersion between selective exposure and post-exposure heating (PEB). When the resist pattern at which the 130-nm line-and-space is 1: 1 is formed by a simulated immersion lithography process which adds a step of bringing the solvent of exposure into contact with the resist film, the sensitivity of [(X2 / The absolute value of X1) -1] x100 is 8.0 or less, and it contains silsesquioxane resin in the resin component. Which it is a positive resist composition.

As a more specific immersion lithography, in the step of immersion exposure, a resist which fills between a resist layer made of the silsesquioxane resin-containing positive resist composition and a lens having a lower refractive index than that of air with a solvent having a refractive index greater than that of air. It is used for a pattern formation method.

It is preferable that the silsesquioxane resin contains at least a silsesquioxane unit containing an acid dissociable, dissolution inhibiting group and a silsesquioxane unit containing an alcoholic hydroxyl group. Also preferred are silsesquioxane resins containing alkylsilsesquioxane units. As a more preferable thing, the 1st silsesquioxane resin of the said invention is mentioned.

By preparing a positive resist containing a resin component containing such a silsesquioxane resin, a resist pattern in which 130 nm line-and-space is 1: 1 is formed by a normal lithography process using a light source having a wavelength of 193 nm. In the lithography process of the normal exposure using the 193 nm light source on the other hand, the sensitivity of the time is X1, The simulation which added the process of contacting the solvent of the said immersion exposure with a resist film between selective exposure and post-exposure heating (PEB). The absolute value of [(X2 / X1) -1] × 100 becomes 8.0 or less when the sensitivity at the time of forming a resist pattern in which the 130-nm line-and-space is 1: 1 by the red immersion lithography process is X2. .

And when the absolute value becomes 8.0 or less, it is suitable as a resist for immersion lithography. Specifically, a resist hardly affected by the immersion solvent and excellent in sensitivity and resist pattern profile shape is obtained. The smaller the absolute value is, the less it is 5 or less, most preferably 3 or less, and the closer to 0, the better.

As the resin component of the positive resist composition, in addition to the silsesquioxane resin as in the second aspect of the present invention, (a1) contains a structural unit derived from a (meth) acrylic acid ester having an acid dissociable, dissolution inhibiting group. When it is set as the mixed resin with a resin component (A2), resolution and heat resistance improve more and are preferable.

The positive resist composition of the fifth aspect of the present invention is useful as a positive resist composition used in a resist pattern forming method including a step of immersion exposure. Such immersion exposure is a method of filling between the resist layer which consists of this positive resist composition, and the lens of the lowest position of an exposure apparatus with the solvent which has a refractive index larger than the refractive index of air.

Moreover, it is also possible to use for the formation method of the resist pattern including the process of immersion exposure of this positive resist composition.

The lithography process of normal exposure using the light source of wavelength 193nm in the 5th aspect of this invention is the resist of the lens of an exposure apparatus, and the wafer on the wafer which are conventionally performed until now using the ArF excimer laser of wavelength 193nm as a light source. By normal exposure which exposes between layers in the state of inert gas, such as air or nitrogen, on a board | substrate, such as a silicon wafer, normal lithography processes, ie, resist coating, prebaking, selective exposure, post-exposure heating, and alkali It means the process of performing image development sequentially. In some cases, a post-baking step may be included after the alkali development, and an organic or inorganic antireflection film may be formed between the substrate and the coating layer of the resist composition.

And the sensitivity X1 at the time of forming the resist pattern (hereinafter referred to as "130 nmL & S") whose 130 nm line-and-space becomes one-to-one by such a lithography process of such normal exposure is the exposure amount in which 130 nmL & S is formed, It is obvious that it is frequently used.

In any case, once this sensitivity is described, an exposure dose is taken on the horizontal axis, a resist line width formed by the exposure amount on the vertical axis, and a logarithmic approximation curve is obtained from the obtained plot by the least square method.

The equation is given by Y = aLoge (X1) + b, where X1 represents the exposure dose, Y represents the resist line width, and a and b represent constants. If we expand this expression and change it to an expression that represents X1,

X1 = Exp [(Y-b) / a]. Introducing Y = 130 (nm) into this equation yields the calculation of ideal sensitivity X1.

In addition, the conditions at that time, that is, the number of revolutions of the resist coating, the prebaking temperature, the exposure conditions, the post-exposure heating conditions, and the alkali developing conditions may be any conditions that are conventionally carried out so far, and are apparent in the range capable of forming 130 nm L & S. . Specifically, a silicon wafer of 8 inches in diameter is used as the substrate, and the rotation speed is about 1000 to 4000 rpm, more specifically about 1500 to 3500 rpm, even more specifically 2000 rpm, and the prebaking temperature is 70 to It is the range of 140 degreeC, Preferably it is 95-110 degreeC (Moreover, it is clear for those skilled in the art to set to the temperature which the line and space of 130 nm becomes 1: 1.) Therefore, [resist] film thickness 80- At 250 nm, more specifically 150 nm, a resist coating film having a diameter of 6 inches is formed concentrically with the substrate.

Exposure conditions, such as ArF excimer laser exposure apparatus Nikon Corporation or Canon Corporation (NA = 0.60) of wavelength 193nm, specifically, exposure apparatus NSR-S302 (made by Nikon Corporation, Na (number of openings) = 0.60, 2/3 wheels) ) May be exposed through a mask. As a mask in selective exposure, a normal binary mask is used. As such a mask, you may use a phase shift mask.

The post-exposure heating is in a temperature range of 70 to 140 ° C., preferably 90 to 100 ° C. (It is obvious to those skilled in the art to set the temperature at which the line and space of 130 nm becomes 1: 1.) Alkali developing conditions are immersed in a 2.38% by weight TMAH (tetramethylammonium hydroxide) developer, followed by development at 23 ° C. for 15 to 90 seconds, more specifically for 60 seconds, followed by water rinsing.

In addition, in the fifth aspect of the present invention, the simulated immersion lithography process is performed by selective exposure and post-exposure heating (PEB) in a lithography process of normal exposure using the above-described 193 nm ArF excimer laser as a light source. Means a step of adding a step of bringing the solvent of the immersion exposure into contact with the resist film.

Specifically, it is a step of sequentially applying a solvent of resist coating, prebaking, selective exposure, or immersion exposure to a resist film, heating after exposure, and alkali development. In some cases, a post bake step may be included after the alkali development.

[With contact, the resist film after selective exposure formed on the board | substrate may be immersed in the solvent of immersion exposure, and may be sprayed like a shower. It is preferable that the temperature at this time shall be 23 degreeC. When spraying like a shower, it can be carried out by rotating the substrate at about 300 to 3000 rpm, preferably at about 500 to 2500 rpm.]

The conditions of the contact are as follows. Pure water is added dropwise to the center of the substrate with a rinse nozzle, during which the wafer on which the resist film is formed after exposure is rotated; The rotation speed of the substrate on which the resist was formed: 500 rpm; Solvent: pure; Solvent dropping amount: 1.0 L / min; Solvent dropping time: 2 minutes to 5 minutes; Contact temperature of the solvent with the resist: 23 ° C.

In addition, the sensitivity X2 at the time of forming a 130 nmL & S resist pattern by such a simulated immersion lithography process is the exposure amount in which 130 nmL & S is formed similarly to said X1, and is normally used by a person skilled in the art.

In addition, the conditions (the conditions of rotation speed of resist coating, prebaking temperature, exposure conditions, post-exposure heating conditions, alkali image development, etc.) at that time are also the same as said X1.

In the fifth aspect, it is necessary that the absolute value of [(X2 / X1) -1] × 100 is 8.0 or less, but this absolute value is apparent when X2 and X1 are obtained as described above.

In addition, in the sixth aspect of the present invention, it is advantageous if a protective film made of a fluorine resin is formed on the upper layer of the resist film to perform immersion exposure. That is, a resist film is first formed on a substrate. Subsequently, a protective film is formed on the resist film, and the immersion exposure liquid is directly disposed on the protective film, the resist film is selectively exposed through the liquid and the protective film, and post-exposure heating is performed. Then, the protective film is removed, and finally, the resist film is developed to form a resist pattern.

The characteristics of the protective film are transparent to the exposure light, do not have substantial compatibility with the liquid for immersion exposure, do not cause mixing with the resist film, and have good adhesion to the resist film, and also resist. The peelability from a film | membrane is good. As a protective film material which can form the protective film which has such a characteristic, what is necessary is just to use the composition which melt | dissolves a fluororesin in a fluorine-type solvent.

As said fluorine-type resin, For example, Chain perfluoroalkyl polyether, Cyclic perfluoroalkyl polyether, Polychlorotrifluoroethylene, Polytetrafluoroethylene, Tetrafluoroethylene- perfluoroalkoxy ethylene copolymer, Tetrafluoroethylene-hexafluoropropylene copolymer etc. can be used.

And practically, in a commercial item, Demnam S-20 which is a chain | strand-type perfluoroalkyl polyether, Demnam S-65, Demnam S-100, Demnam S-200 (above, Daikin Industries Co., Ltd.), and cyclic perfluoroalkyl Cytop series which is polyether (made by Asahigara Corporation), Teflon (R) -AF1600, Teflon (R) -AF2400 (above, DuPont company), etc. can be used.

Among the fluorine-based resins, a mixed resin composed of a chain perfluoroalkyl polyether and a cyclic perfluoroalkyl polyether is preferable.

In addition, the fluorine-based solvent may be any solvent capable of dissolving the fluorine-based resin, and is not particularly limited. Perfluoroalkenes with double bonds remaining, perfluoro cyclic ethers such as perfluorotetrahydrofuran and perfluoro (2-butyltetrahydrofuran), perfluorotributylamine, perfluorotetra Fluorine solvents, such as a pentylamine and a perfluoro tetrahexylamine, can be used.

Moreover, other organic solvents, surfactants, etc. which are compatible with these fluorine-type solvents can also be mixed suitably and used.

The concentration of the fluorine-based resin is not particularly limited as long as it is within a range in which a film can be formed.

As a preferable protective film material, it is preferable to set it as the structure which melt | dissolved the mixed resin which consists of chain perfluoroalkyl polyether and cyclic perfluoroalkyl polyether in perfluoro tributylamine.

As the solvent for removing the protective film, the same solvent as the fluorine-based solvent can be used.

The fifth or the sixth exposure wavelength in the aspect (aspect) is not limited particularly, KrF excimer laser, ArF excimer laser, F ₂ excimer laser, EUV (extreme ultraviolet light) of the present invention, VUV (vacuum ultraviolet light), Although radiation, such as an electron beam, a soft X-ray, and X-rays, can be used, Especially preferably, it is ArF excimer laser.

<Example>

Next, although an Example demonstrates this invention further in detail, this invention is not limited to these examples. In addition, a compounding quantity is mass% unless there is particular notice.

In the following examples, the conditions of simulated immersion lithography and sensitivity measurement are as follows unless otherwise specified.

(1) Formation Conditions of Resist Coating Film:

Substrate: 8 inch silicon wafer;

Resist coating method: application using a spinner on a substrate rotating at 2000 rpm;

Size of resist coating film: 6 inches in diameter, 150 nm thick concentrically on the substrate;

Prebaking conditions: 90 seconds at 110 ° C. (Example 5) or 60 seconds at 95 ° C. (Example 7)

Selective exposure conditions: exposure using ArF excimer laser (193 nm) (exposure device NSR-S302B (manufactured by Nikon Corporation, Na (number of openings) = 0.60, 2/3 wheels))

(2) Contact Conditions of Resist Coating Film and Solvent

Rotational speed of the substrate: 500 rpm;

Solvent: water;

Solvent dropping amount: 1.0 L / min;

Solvent dropping time: 2 minutes or 5 minutes;

Contact temperature of the solvent with the resist: 23 ° C.

(3) Pattern formation condition of resist

Post exposure exposure conditions: 90 seconds at 90 ° C. (Example 5) or 60 seconds at 90 ° C. (Example 7)

Alkali development conditions: at 23 ° C. for 60 seconds with a 2.38% by mass tetramethylammonium hydroxide aqueous solution;

Synthesis Example 1

20.0 g of hexafluoroisopropanol norbornene, 0.02 g of isopropanol solution of 20 mass% chloroplatinic acid, and 30 g of tetrahydrofuran were poured into a 200 ml flask, and the mixture was heated and stirred to 70 ° C. Then, 9.2 g of tetrachlorosilane was dripped at the solution over 15 minutes. After stirring for 5 hours, it distilled and 15 g of hexafluoroisopropanol norbornyl trichlorosilane (Si containing monomer of following formula [Formula 29]) were obtained.

Then, 10 g of the Si-containing monomer, 10 g of toluene, 10 g of methyl isobutyl ketone, 1.0 g of potassium hydroxide, and 5 g of water were added to a 200 ml flask and stirred for 1 hour. Thereafter, the mixture was diluted with methyl isobutyl ketone and washed with 0.1 N hydrochloric acid so that the pH was 8 or less. Subsequently, the obtained solution was filtered and stirred at 200 degreeC for 12 hours, and the polymer of the mass mean molecular weight 5000 was obtained. After cooling, 30 g of tetrahydrofuran was added, followed by stirring for 1 hour. The solution was added dropwise to pure water, and the precipitates were collected by filtration and dried in vacuo to obtain 6.5 g of a white powdery silsesquioxane polymer.

* 5 g of the obtained polymer, 10 g of tetrahydrofuran, and 3 g of sodium hydroxide were placed in a 100 ml flask, and 3 g of 2-methyl-2-adamantylbromoacetic acid ester was slowly added dropwise. After stirring for 1 hour, 100 g of pure water was precipitated to obtain a solid polymer. It was further dissolved in methanol and purified by ion exchange resin. This solution was dripped at pure water, and it vacuum-dried to obtain the silsesquioxane resin (polymer (x)) made into the objective of 4g of white powder. The structural formula is shown in [Chem 30]. The degree of dispersion of the polymer (x) was 1.14. In addition, the ratio of each structural unit was [i]: [ii] = 80: 20 (molar ratio), respectively.

[Tue 29]

[Tue 30]

Example 1

4 g of polymer (x) obtained in Synthesis Example 1 was dissolved in 75.9 g of ethyl lactate, and 0.12 g of triphenylsulfonium nonaphthalate and 0.008 g of tri-n-pentylamine were added to prepare a positive resist composition.

Next, on the silicon substrate, as a lower resist material, a solution obtained by dissolving a novolak resin obtained by condensing m-cresol, p-cresol, and formalin with an oxalic acid catalyst in an organic solvent was applied using a spinner, and then 90 degrees at 250 ° C. Bake treatment was performed for a second time to form a lower resist layer having a film thickness of 300 nm.

On the lower resist layer, the obtained positive resist composition was first applied using a spinner, prebaked at 90 ° C. for 90 seconds, and dried to form an upper resist layer having a thickness of 100 nm to form a resist laminate.

Subsequently, an ArF excimer laser (193 nm) was selectively subjected to the upper resist layer by an ArF exposure apparatus NSR-S302 (manufactured by Nikon Corporation; Na (number of openings) = 0.60, σ = 0.75) through a binary mask pattern. Investigate.

Then, the PEB treatment was carried out at 90 ° C. for 90 seconds, and further developed at 23 ° C. for 60 seconds with an aqueous 2.38% by mass tetramethylammonium hydroxide solution to form a 120 nm line and space (L & S) pattern having a high rectangularity ( I) was obtained.

The L & S pattern (I) was subjected to dry etching using an oxygen plasma using a high vacuum RIE apparatus (manufactured by Tokyo Oka Industry Co., Ltd.) to form the L & S pattern (II) on the lower resist layer.

The obtained L & S pattern (II) was a perpendicular | vertical thing with a 120 nm dimension.

As a test for degassing, the prepared positive resist composition was applied on a silicon wafer at a film thickness of 2.0 m to form a resist film. Subsequently, 10000 shots of 193 nm wavelength light were irradiated at 1000 mJ / cm <2> using the exposure apparatus provided with the gas collection tube, and the gas produced at that time was collected, flowing in the nitrogen stream. When the collected gas was analyzed by GC-MS, the gas of the organosilicon system was not detected. In addition, about 150 ng of organic non-silicon-based gas generated when the acid dissociable, dissolution inhibiting group was dissociated or from the resist solvent was detected.

In addition, the permeability of the polymer (x) obtained in the synthesis example 1 was measured as follows. The polymer (x) was dissolved in an organic solvent and coated on a magnesium fluoride wafer so that the film thickness after drying might be 0.1 μm. After drying this coating film and forming a resin film, transparency (absorption coefficient) with respect to each light of wavelength 193nm and 157nm was measured using the vacuum ultraviolet spectrophotometer (made by Nippon Spectrophotometer, Inc.).

As a result, it was 3.003abs / micrometer for 157nm, and 0.0879abs / micrometer for 193nm.

Synthesis Example 2

In the synthesis example 1, it carried out similarly to the synthesis example 1 except having changed 2-methyl- 2-adamantyl bromoacetic acid ester into 2-ethyl- 2-adamantyl bromoacetic acid ester, The polymer (x1) in which the 2-methyl-2-adamantyl group of the obtained polymer (x) was 2-ethyl-2-adamantyl group was obtained.

Example 2

In Example 1, except having changed the polymer (x) obtained by the synthesis example 1 into the polymer (x1) obtained by the synthesis example 2, it carried out similarly to Example 1, and prepared the positive resist composition. Next, in the same manner as in Example 1, a resist laminate was formed. In addition, when the resist pattern was formed in the same manner as in Example 1, a 120-nm line-and-space (L & S) pattern (I) having a high rectangularity was obtained, and a 120-nm line-and-space L & S pattern ( II) was formed.

Synthesis Example 3

Polymer of Structural Formula shown in Synthesis Example 1 as white transparent [Formula 31] except that 20.0 g of hexafluoroisopropanol norbornene was changed to 12 g of perfluoroisopentanol norbornene in Synthesis Example 1 x2) was obtained.

[Tue 31]

Example 3

A positive resist composition was prepared in the same manner as in Example 1 except that the polymer (x) obtained in Synthesis Example 1 was changed to the polymer (X2) obtained in Synthesis Example 3. Next, in the same manner as in Example 1, a resist laminate was formed. In addition, when the resist pattern was formed in the same manner as in Example 1, a 120 nm line-and-space (L & S) pattern (I) having a high rectangularity was obtained, and a line-and-space L & S pattern of 120 nm was similarly applied to the lower resist layer. (II) was formed.

Comparative Example 1

Instead of the polymer (x) of Example 1, the polymer of the structural formula shown in [Formula 32] (in the polymer of Synthesis Example 3, the acid dissociable, dissolution inhibiting group is a 2-methyl-2-adamantyl group to a 1-ethoxyethyl group). The resist pattern was formed like Example 1 except having changed).

As a result, the upper resist layer was resolved only up to 140 nm. Moreover, when the same measurement as the test of the degassing in Example 1 was performed, about 600 mg of organic non-silicon gas which was generate | occur | produced when an acid dissociable, dissolution inhibiting group dissociated, or from a resist solvent was detected.

[Tue 32]

Comparative Example 2

Instead of the positive resist composition of Example 1, poly- [p-hydroxybenzylsilsesquioxane-co-p-methoxybenzyl described in Example 4 of JP-A-6-202338 (or EP0599762). It is implemented except using the resist composition which consists of a propylene glycol monomethyl ether solution of silsesquioxane-co-p- (1-naphthoquinone-2- diazide-4-sulfonyloxy) -benzyl silsesquioxane] In the same manner as in Example 1, a resist pattern was formed.

As a result, the L & S pattern (I) formed in the upper resist layer was round with low rectangularity, and the limit resolution was only 180 nm. In addition, the dimensions of the L & S pattern (I) and the L & S pattern (II) of the lower resist layer were different. Could not transfer to lower resist.

Example 4

The following (A) component, (B) component, the organic solvent component, and the quencher component were mixed and dissolved, and the positive resist composition was adjusted.

As the component (A), 85 parts by mass of a polymer (x) obtained in Synthesis Example 1 and a mixed resin of 15 parts by mass of a copolymer of methacrylic acid ester and acrylic acid ester composed of the three types of structural units shown in Fig. 33 were used. . The ratio of each structural unit p, q, and r of this copolymer was p = 50 mol%, q = 30 mol%, r = 20 mol%, and the mass mean molecular weight was 10000.

* [Tue 33]

As the component (B), 3 parts by mass of triphenylsulfonium nonafluorobutanesulfonate was used.

As an organic solvent component, the mixed solvent of 1900 mass parts (mass ratio 6: 4) of the mixed solvent of propylene glycol monomethyl ether acetate and ethyl lactate was used.

As the quencher component, 0.25 parts by mass of triethanolamine was used.

Next, on the lower resist layer formed in the same manner as in Example 1 using the positive resist composition obtained above, the prebaking temperature was changed to 100 ° C., and the film thickness of the upper resist layer was changed to 150 nm. Except for the above, the upper resist layer was formed in the same manner as in Example 1 to form a resist laminate.

Subsequently, in Example 1, the mask was changed from a binary mask to a halftone mask, and the post-exposure heating temperature was maintained at 90 ° C., except that post-baking was performed at 100 ° C. for 60 seconds for the developed resist pattern. In the same manner as in Example 1, a resist pattern was formed.

The resist pattern which becomes 120-nm line and space of 1: 1 obtained by this was observed with the scanning electron microscope (SEM), and the rectangle was a favorable pattern. Moreover, the sensitivity (Eth) at that time was 28.61 mJ / cm <2>. Moreover, the exposure margin obtained in the range whose 120-nm line pattern is +/- 10% was favorable at 10.05%. In addition, the depth of focus obtained with a line-and-space of 120 nm in a 1: 1 ratio of 0.6 µm was sufficient. In addition, the limit resolution was 110 nm.

Example 5 (immersion exposure)

In the positive resist composition obtained in Example 4, a positive resist composition was obtained in the same manner as in Example 4 except that triethanolamine was changed to 0.38 parts by mass.

Next, on the lower resist layer formed in the same manner as Example 1 using the positive resist composition obtained above, the prebaking temperature was changed to 110 degreeC, and the film thickness of the upper resist layer was changed to 150 nm. Except for the above, the upper resist layer was formed in the same manner as in Example 1 to form a resist laminate.

Next, it selectively irradiated using the ArF excimer laser (193 nm) with exposure apparatus NSR-S302B (made by Nikon Corporation, Na (number of openings) = 0.60, 2/3 ring zone) through the position shift mask pattern. And pure water was continuously dripped at 23 degreeC for 5 minutes, rotating the silicon wafer which formed the resist layer after the exposure as an immersion exposure process.

Next, PEB treatment was carried out on the conditions of 90 degreeC and 90 second, and it developed further with alkali developing solution at 23 degreeC for 60 second. As an alkaline developer, 2.38 mass% tetramethylammonium hydroxide aqueous solution was used.

Thus, the resist pattern which becomes 130 nm line and space of 1: 1 was observed with the scanning electron microscope (SEM), and the sensitivity (Eth) at that time was calculated | required.

In the positive resist composition of this example, Eth was 17.0 mJ / cm 2. Let this be X2. In addition, the resist pattern was satisfactory without showing surface roughness.

On the other hand, Eth was 18.0 mJ / cm <2> when the resist pattern was formed by the exposure method (normal exposure) in the air currently performed, without performing the said immersion exposure process using the positive resist composition of a present Example. Let this be X1.

Then, the absolute value was calculated | required from the formula of [(X2 / X1) -1] x100, and it was 5.56. It was 0.94 when the sensitivity ratio of the immersion exposure process with respect to the sensitivity of normal exposure was calculated | required. Moreover, the surface roughness was not seen, and the resist pattern was favorable.

Synthesis Example 4

20.0 g of hexafluoroisopropanol norbornene, 0.02 g of isopropanol solution of 20 mass% chloroplatinic acid, and 30 g of tetrahydrofuran were poured into a 200 ml flask, and the mixture was heated and stirred to 70 ° C. Then, 9.2 g of tetrachlorosilane was dripped at the solution over 15 minutes. After stirring for 5 hours, it distilled and obtained 15 g of hexafluoroisopropanol norbornyl trichlorosilane (Si containing monomer of [Formula 29]).

Subsequently, 10 g of the Si-containing monomer, 1.36 g of methyltrimethoxysilane (Si-containing monomer of [34]), 10 g of toluene, 10 g of methyl isobutyl ketone, 1.0 g of potassium hydroxide, and 5 g of water were added to a 200 ml flask for 1 hour. Stirred. Thereafter, the mixture was diluted with methyl isobutyl ketone and washed with 0.1 N hydrochloric acid so that the pH was 8 or less. Subsequently, the obtained solution was filtered and stirred at 200 degreeC for 12 hours, and the polymer of the mass mean molecular weight 7700 was obtained. After cooling, 30 g of tetrahydrofuran was added, followed by stirring for 1 hour. The solution was added dropwise to pure water, and the precipitates were collected by filtration and dried in vacuo to obtain 8 g of a white powdery silsesquioxane polymer.

[Tue 34]

*

Thus obtained 5 g of the polymer, 10 g of tetrahydrofuran and 3 g of sodium hydroxide were poured into a 100 ml flask, and 3 g of 2-methyl-2-adamantylbromoacetic acid ester was slowly added dropwise. After stirring for 1 hour, 100 g of pure water was precipitated to obtain a solid polymer. It was further dissolved in methanol and purified by ion exchange resin. The solution was dripped in pure water, and it dried in vacuum and obtained the silsesquioxane resin (polymer (x3)) made into the objective of 4g of white powder. The structural formula is shown in Fig. 35. The degree of dispersion of the polymer (x3) was 1.93. In addition, the ratio of each structural unit was [i]: [ii]: [iii] = 60: 10: 30 (molar ratio).

[Tue 35]

Example 6

The following (A) component, (B) component, the amine component as a quencher, and the organic carboxylic acid component as a quencher were mixed-dissolved and the positive resist composition was adjusted.

As the component (A), 85 parts by mass of a polymer (X3) obtained in Synthesis Example 3 and a mixed resin of 15 parts by mass of a copolymer of methacrylic acid ester and acrylic acid ester composed of the three types of structural units shown in Fig. 36 were used. . The ratio of each structural unit s, t, u of this copolymer was s = 40 mol%, t = 40 mol%, u = 20 mol%, and the mass average molecular weight was 10000.

[Tue 36]

As the component (B), 2.4 parts by mass of triphenylsulfonium nonafluorobutanesulfonate was used.

As an organic solvent component, the mixed solvent of 1900 mass parts (mass ratio 8: 2) of the mixed solvent of ethyl lactate and (gamma) -butyrolactone was used.

As an amine component as a quencher, 0.27 mass parts of triethanolamines were used.

0.26 mass part of salicylic acid was used as an organic carboxylic acid component as a quencher.

Next, an organic antireflection film composition "AR-19" (trade name, manufactured by Shipley) was applied onto the silicon wafer using a spinner, fired at 215 ° C for 60 seconds on a hot plate, and dried to form an organic system having a film thickness of 82 nm. An antireflection film was formed. The positive resist composition was apply | coated on this anti-reflective film using the spinner, prebaked at 95 degreeC for 60 second on a hotplate, and dried, and the resist layer of 150 nm in thickness was formed on the anti-reflective film.

Next, using an ArF excimer laser (193 nm) through a phase shift mask, the exposure apparatus NSR-S302B (made by Nikon Corporation, Na (number of openings) = 0.60, 2/3 wheels | bands) through a mask pattern was then selectively used. Investigate. Next, PEB treatment was carried out under the conditions of 90 ° C. and 60 seconds, and further developed at 23 ° C. for 60 seconds with an alkaline developer. As an alkaline developer, 2.38 mass% tetramethylammonium hydroxide aqueous solution was used.

In this way, when the resist pattern which becomes 130 nm of line and space obtained by 1: 1 was observed with the scanning electron microscope (SEM), the rectangle was a favorable pattern. Moreover, the sensitivity (Eth) at that time was 24.0 mJ / cm <2>. Moreover, the exposure margin obtained in the range whose 130-nm line pattern is +/- 10% was favorable at 13.31%. In addition, the depth of focus obtained with a line-and-space of 130 nm in a 1: 1 ratio of 0.6 µm was sufficient. In addition, the limit resolution was 110 nm.

Example 7 (immersion exposure)

Immersion exposure treatment was performed using the positive resist composition prepared in Example 6.

First, an organic antireflection film composition "AR-19" (trade name, manufactured by Shipley) was applied onto a silicon wafer using a spinner, baked at 215 ° C. for 60 seconds on a hot plate, and dried to form an organic reflection having a film thickness of 82 nm. A protective film was formed. A positive resist composition was applied onto the antireflection film using a spinner, prebaked at 95 ° C. for 60 seconds on a hot plate, and dried to form a resist layer having a thickness of 150 nm on the antireflection film.

Next, using an ArF excimer laser (193 nm) through a halftone phase shift mask, the exposure apparatus NSR-S302B (made by Nikon Corporation, Na (number of openings) = 0.60, 2/3 ring zone) was used through a mask pattern. It was investigated selectively. As the simulated immersion lithography treatment, pure silicon was continuously added dropwise at 23 ° C. for 2 minutes while rotating the silicon wafer on which the resist layer after exposure was formed at 2000 rpm for 5 seconds and then at 500 rpm for 115 seconds.

Next, PEB treatment was carried out under the conditions of 90 ° C. and 60 seconds, and further developed at 23 ° C. for 60 seconds with an alkaline developer. As an alkaline developer, 2.38 mass% tetramethylammonium hydroxide aqueous solution was used.

In this way, the resist pattern which becomes 130 nm line and space of 1: 1 was observed with the scanning electron microscope (SEM), and the sensitivity (Eop) at that time was calculated | required.

In the positive resist composition of the present Example, Eop was 25.0 mJ / cm <2>. Let this be X2. In addition, the resist pattern showed neither surface roughness nor swelling, and was favorable.

On the other hand, using the positive resist composition used in the present embodiment, the above-described immersion lithography treatment is not carried out, and the conventional method is performed in the same manner except that the lithography process of conventional exposure, that is, the mock immersion lithography treatment is not performed. In Example 6 in which a resist pattern was formed, Eop was 24.0 mJ / cm 2. Let this be X1.

Then, the absolute value was calculated | required from the formula of [(X2 / X1) -1] x100, and it was 4.16. It was (25.0 / 24.0) and 1.04 when the sensitivity ratio of the simulated immersion exposure process with respect to the sensitivity of normal exposure was calculated | required. In addition, in the profile of this pattern, neither surface roughness nor swelling was favorable. Moreover, the exposure margin obtained in the range whose 130-nm line pattern is +/- 10% was favorable at 12.97%. In addition, the limit resolution was 110 nm.

Example 8 (immersion exposure)

The following (A) component, (B) component, the amine component as a quencher, and the organic carboxylic acid component as a quencher were mixed-dissolved and the positive resist composition was adjusted.

As the component (A), 85 parts by mass of a polymer (X3) obtained in Synthesis Example 4 and a mixed resin of 15 parts by mass of a copolymer of methacrylic acid ester and acrylic acid ester composed of three structural units shown in [Sec. 37] were used. . The ratio of each structural unit v, w, x of this copolymer was v = 40 mol%, w = 40 mol%, x = 20 mol%, and the mass average molecular weight was 10000.

[Tue 37]

As the component (B), 2.4 parts by mass of triphenylsulfonium nonafluorobutanesulfonate was used.

As an organic solvent component, the mixed solvent of 1150 mass parts (mass ratio 8: 2) of the mixed solvent of ethyl lactate and (gamma) -butyrolactone was used.

As an amine component as a quencher, 0.27 mass parts of triethanolamines were used.

0.26 mass part of salicylic acid was used as an organic carboxylic acid component as a quencher.

Next, an organic antireflection film composition "AR-19" (trade name, manufactured by Shipley) was applied onto the silicon wafer using a spinner, fired at 215 ° C for 60 seconds on a hot plate, and dried to form an organic system having a film thickness of 82 nm. An antireflection film was formed. The positive resist composition was apply | coated on this anti-reflective film using the spinner, prebaked and dried for 90 second at 95 degreeC on the hotplate, and the resist layer of 150 nm of film thickness was formed on the anti-reflective film.

Next, on the resist film, a mixed resin composed of Demnam S-10 (manufactured by Daikin Industries Co., Ltd.) and Cytop (manufactured by Asahi Glass Co., Ltd.) (mixed weight ratio = 1: 5) was dissolved in perfluorotributylamine, A fluorine-based protective film material having a resin concentration of 2.5 wt% was applied by rotary coating and heated at 90 ° C. for 60 seconds to form a protective film having a film thickness of 37 nm.

And as evaluation test 2, the immersion exposure performed the experiment (two-beam interference experiment) by the prism and water and two light beam interferences of 193 nm using the experimental apparatus made from Nikon Corporation. The same method is disclosed also in the said nonpatent literature 2, and it is well-known as a method of obtaining an L & S pattern simply at a laboratory level.

In the immersion exposure in Example 8, an aqueous medium layer was formed as an immersion solvent between the upper surface of the protective film and the lower surface of the prism.

Moreover, the exposure amount selected the exposure amount from which an L & S pattern is obtained stably. Next, PEB treatment was performed at 90 degreeC for 90 second conditions, and the protective film was removed using perfluoro (2-butyltetrahydrofuran). Thereafter, development was conducted in the same manner as in Example 1, whereby a 65 nm line and space (1: 1) was obtained. The pattern shape was highly rectangular.

From the results of these Examples 1 to 3 and Comparative Examples 1 and 2, in the two-layer resist method as described above, by using a positive resist composition containing the silsesquioxane resin of the present invention, 200 nm or less Even when the high energy light and the electron beam are used as the exposure light source, it is clear that the degassing phenomenon can be reduced, and a resist pattern having a dimension of about 100 nm can be formed in a good aspect ratio with a high aspect ratio. In addition, the positive resist composition has high resolution having high transmittance to high energy light or electron beam of 200 nm or less and high resolution.

In addition, from the results of Example 4, by using a positive resist composition containing a mixed resin of the silsesquioxane resin and the (meth) acrylic acid ester resin of the present invention, a resist pattern having a dimension of about 100 nm was shaped at a high aspect ratio. It is clear that, furthermore, it is possible to form a resist pattern having excellent exposure margin and depth of focus.

Moreover, even if the positive resist composition containing the mixed resin of the silsesquioxane resin and the (meth) acrylic acid ester resin of this invention is used for a single layer from the result of Example 6, the resist pattern of the dimension of about 100 nm is shaped. It is clear that, furthermore, it is possible to form a resist pattern having excellent exposure margin and depth of focus.

In addition, from the immersion exposure results of Examples 5, 7 and 8, it can be seen that the positive resist composition of the present invention is also preferable to an immersion process using a water medium. That is, it can be seen that a good resist pattern without surface roughness can be formed, and the sensitivity ratio is not adversely affected by the water medium to the same extent as in normal exposure. In addition, when the water medium is adversely affected, surface roughness occurs in the resist pattern or the sensitivity ratio is 10% or more.

As explained above, by the silsesquioxane resin of this invention, the positive resist composition containing this silsesquioxane resin, the laminated body using this positive resist composition, and the resist pattern formation method using this laminated body The degassing phenomenon can be reduced, and high transparency can form a high resolution resist pattern. In addition, the present invention provides a positive resist composition and a method of forming a resist pattern suitable for an immersion lithography process.

The present invention can be used for forming a resist pattern and is very useful industrially.

Claims (18)

The following general formulas [1] and [2]: [Tue 1]

[Wherein, R ¹ and R ² are each independently a linear, branched or cyclic saturated aliphatic hydrocarbon group, R ³ is an acid dissociable, dissolution inhibiting group consisting of a hydrocarbon group containing an aliphatic monocyclic or polycyclic group, R ⁴ is a hydrogen atom or a linear, branched or cyclic alkyl group, Each X is independently an alkyl group having 1 to 8 carbon atoms in which at least one hydrogen atom is substituted with a fluorine atom, m is an integer of 1 to 3], A silsesquioxane resin, wherein the ratio of the structural units represented by the general formula [1] is 5 to 70 mol% with respect to the sum of the structural units represented by the general formulas [1] and [2]. The silsesquioxane resin according to claim 1, wherein R ¹ and R ² are each independently a cyclic saturated aliphatic hydrocarbon group. The method according to claim 1, wherein R ¹ and R ² are each independently the following formulas [3] to [8]: [Tue 2]

And silsesquioxane resins having two hydrogen atoms removed from an alicyclic compound selected from the group consisting of derivatives thereof. A compound according to claim 1, wherein R ³ is represented by the following formulas [9] to [13]: [Tue 3]

Silsesquioxane resin which is group chosen from the group which consists of these. A compound according to claim 1, wherein the general formulas [14] and [15] are: [Tue 4]

Wherein R ¹ and R ² are each independently a linear, branched or cyclic saturated aliphatic hydrocarbon group, R ⁵ is a lower alkyl group and n is an integer of 1 to 8; Silsesquioxane resin having a. A compound according to claim 1 further comprising the following general formula [17]: [Tue 5]

In the formula, R 'represents a linear or branched lower alkyl group. Silsesquioxane resin having a structural unit represented by. The positive type resist composition containing the resin component (A) which increases alkali solubility by the action of an acid, and the acid generator component (B) which generates an acid by exposure, The said (A) component is a claim 1 The positive resist composition containing silsesquioxane resin (A1) of description. The resin component (A2) according to claim 7, wherein the resin component (A) contains a structural unit derived from the (meth) acrylic acid ester having the silsesquioxane resin (A1) and (a1) an acid dissociable, dissolution inhibiting group. It is mixed resin with, Positive type resist composition characterized by the above-mentioned. The positive type resist composition according to claim 8, wherein the component (A2) has a structural unit derived from a (meth) acrylic acid ester having a lactone unit (a2). The content of each of the structural units (a1) and (a2) in the component (A2) is (a1) 20 to 60 mol%, and (a2) 20 to 60 mol%. A positive resist composition, characterized in that. The positive resist according to any one of claims 8 to 10, wherein the component (A2) has a structural unit derived from (meth) acrylic acid ester having an alcoholic hydroxyl group-containing polycyclic group. Composition. The structural unit according to claim 8, wherein the component (A2) is derived from a (meth) acrylic acid ester having an acid dissociable, dissolution inhibiting group, or a structural unit derived from a (meth) acrylic acid ester having a (a2) lactone unit. , And (a3) a structural unit derived from (meth) acrylic acid ester having an alcoholic hydroxyl group-containing polycyclic group, wherein the respective contents of the respective structural units (a1) to (a3) in the component (A2) are ( a1) 20-60 mol%, (a2) 20-60 mol%, and (a3) 5-50 mol% positive type resist composition characterized by the above-mentioned. The positive resist composition according to claim 7, wherein the component (B) contains a triphenylsulfonium salt. A resist laminate in which a lower resist layer and an upper resist layer are laminated on a support, The lower resist layer is insoluble in the alkaline developer and dry-etchable; The said upper resist layer consists of a positive resist composition of Claim 7, The resist laminated body characterized by the above-mentioned. The resist laminate according to claim 14, wherein the lower resist layer is dry-etched by oxygen plasma. The resist laminate according to claim 14, wherein the lower resist layer contains at least one selected from the group consisting of novolak resins, acrylic resins, and soluble polyimides. After selectively exposing to the resist laminated body of Claim 14, performing post-exposure heating (PEB), alkali-development, and forming the resist pattern (I) in the said upper resist layer, the resist pattern (I) is made into Dry etching is carried out as a mask, and a resist pattern (II) is formed in the lower resist layer. 18. The method of claim 17, wherein, when selectively exposed, an ArF excimer laser is used as exposure light.