JP2011017902A - Chemically amplified resist material and pattern formation method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pattern formation method that reduces roughness produced on a resist pattern to make the pattern have a good shape.SOLUTION: At first, a resist film 102 is formed from a chemically amplified resist material onto a substrate 101. The resist film 102 is irradiated with an exposure light comprising extreme ultraviolet light in a selective manner to achieve pattern exposure. The resist film 102 that has been subjected to pattern exposure is heated, and the heated resist film 102 is developed to form a resist pattern 102a from the resist film 102. The chemically amplified resist material comprises a block polymer comprising a first monomer unit and a second monomer unit, wherein the first monomer unit has an onium salt having an anionic moiety and a cationic moiety and contains a group covalently bound to a sulfonate group that is the anionic moiety, and wherein the second monomer unit contains an acid leaving group.

Description

  The present invention relates to a chemically amplified resist material used in a semiconductor device manufacturing process and the like and a pattern forming method using the same.

  Along with the large integration of semiconductor integrated circuits and downsizing of semiconductor elements, acceleration of development of lithography technology is desired. At present, as exposure light, pattern formation is performed by photolithography using a mercury lamp, a KrF excimer laser, an ArF excimer laser, or the like. In recent years, use of extreme ultraviolet rays in which the wavelength of exposure light is further shortened has been studied. Extreme ultraviolet rays have a wavelength of 13.5 nm, which is shorter than one-tenth of that of conventional photolithography, so that a significant improvement in resolution can be expected.

  A chemically amplified resist is used to form such a fine pattern including exposure to extreme ultraviolet rays. The chemically amplified resist is a resist material essential for improving the resolution. An acid is generated by exposure light from the photoacid generator in the resist, and the generated acid causes a chemical reaction in the resist, leading to pattern formation.

  Hereinafter, a conventional pattern forming method will be described with reference to FIGS. 5 (a) to 5 (d) and FIG.

  First, a positive chemically amplified resist material having the following composition is prepared.

Poly (2-methyl-2-adamantyl methacrylate (50 mol%)-γ-butyrolactone methacrylate (40 mol%)-2-hydroxyadamantane methacrylate (10 mol%)) (main polymer) ... 2g
Triphenylsulfonium trifluoromethanesulfonic acid (photoacid generator) ... ... 0.05g
Triethanolamine (quencher) ... 0.002g
Propylene glycol monomethyl ether acetate (solvent) 20g
Next, as shown in FIG. 5A, the chemically amplified resist material is applied onto the substrate 1, and subsequently heated at 90 ° C. for 60 seconds to form a resist film having a thickness of 60 nm. 2 is formed.

  Next, as shown in FIG. 5B, pattern exposure is performed by selectively irradiating the resist film 2 with exposure light composed of extreme ultraviolet rays having a numerical aperture (NA) of 0.25 and a wavelength of 13.5 nm. Do.

  Next, as shown in FIG. 5C, the resist film 2 subjected to the pattern exposure is heated with a hot plate at a temperature of 105 ° C. for 60 seconds.

  Next, the heated resist film 2 is developed with a tetramethylammonium hydroxide developer having a concentration of 2.38 wt%, and the resist film 2 is not exposed as shown in FIG. A resist pattern 2a having a line width of 30 nm is obtained.

JP 2006-178317 A

  However, according to the conventional pattern formation method using the chemically amplified resist material, as shown in the sectional view of FIG. 5D and the plan view of FIG. 6, the formed resist pattern 2a has a large degree of roughness. (For example, the standard deviation (3σ) is 8 nm).

  As described above, when etching is performed on the film to be processed using the resist pattern 2a having a poor shape, the shape of the pattern obtained from the film to be processed also becomes defective. In addition, the yield decreases.

  In view of the above-described conventional problems, an object of the present invention is to realize a pattern forming method having a good shape by reducing roughness generated in a resist pattern by a chemically amplified resist.

  As a result of various studies on the cause of the increased pattern roughness due to the chemically amplified resist, the present inventors have found that the conventional chemically amplified resist material has a large degree of acid diffusion from the photoacid generator after exposure. It is also concluded that the reaction between the acid and the polymer in the resist is irregular.

  On the other hand, as a result of further investigation, a chemically amplified resist material has an onium salt having an anion portion and a cation portion, and contains a group covalently bonded to a sulfonic acid group that is an anion portion of the onium salt. It has been found that the roughness of the pattern can be reduced by using a polymer containing a block polymer containing one monomer unit and a second monomer unit containing an acid leaving group.

  In the block polymer containing the second monomer unit containing an acid leaving group, the difference in the degree of reaction is extremely small because the acid leaving groups that react during exposure are regularly arranged. Further, when the first monomer unit contains an onium salt containing a sulfonic acid group, an acid can be generated in the polymer itself. By synergizing these effects, a good pattern with a small degree of roughness can be formed.

  In addition, although the polymer containing onium salt is described in said patent document 1, it has 1st monomer which has onium salt and has the group covalently bonded with the sulfonic acid group which is an anion part of this onium salt A block polymer comprising a unit and a second monomer unit comprising an acid leaving group is not described.

  The present invention is made on the basis of the above-described knowledge, and is specifically realized by the following configuration.

  The chemically amplified resist material according to the present invention includes an onium salt having an anion portion and a cation portion, a first monomer unit including a group covalently bonded to a sulfonic acid group that is an anion portion, and an acid leaving group. And a block polymer including a second monomer unit.

  According to the chemically amplified resist material of the present invention, the polymer has a first monomer unit containing a group having an onium salt having an anion part and a cation part and a group covalently bonded to a sulfonic acid group being an anion part as a block polymer. And a second monomer unit containing an acid leaving group. By this block polymer, the acid leaving groups that react during exposure are regularly arranged, so that the difference depending on the location of the acid elimination reaction is extremely small. Moreover, since an onium salt containing a sulfonic acid group is included, an acid is generated from the polymer itself. By these, the pattern which has a favorable shape with small roughness can be obtained.

  In the chemically amplified resist material of the present invention, triphenylsulfonium, diphenyl (p-t-butylphenyl) sulfonium, diphenyliodonium, or di (p-t-butylphenyl) iodonium can be used for the cation portion of the onium salt.

  In the chemically amplified resist material of the present invention, the acid leaving group of the onium salt includes an acetal group, a cyclohexylmethyl group, a cyclohexylethyl group, a cyclopentylmethyl group, a cyclopentylethyl group, a t-butyl group, or a t-butyloxycarbonyl group. Can be used.

  In this case, a 1-ethoxyethyl group, a methoxymethyl group, or a 1-ethoxymethyl group can be used for the acetal group.

  In the chemically amplified resist material of the present invention, the first monomer unit may contain styrene, xylene, or ethylene, and the second monomer unit may contain methacrylate or acrylate.

  In addition, it is mentioned that the ratio of the 2nd monomer unit in the block polymer which concerns on this invention shall be 50 mol% or more. More preferably, the second monomer unit containing an acid leaving group may be 60 mol% or more.

  The block polymer according to the present invention is usually used as a main polymer in a resist material, but may be used by mixing with a conventional polymer (a polymer that is not a block polymer). Also in this case, a certain effect of roughness reduction can be obtained.

  The pattern forming method according to the present invention includes a step of forming a resist film from a chemically amplified resist material on a substrate, a step of performing pattern exposure by selectively irradiating the resist film with exposure light, and a pattern exposure. And a step of developing the heated resist film to form a resist pattern from the resist film. The chemically amplified resist material has an anion portion and a cation portion. And a block polymer including a first monomer unit including a group covalently bonded to a sulfonic acid group which is an anion moiety and a second monomer unit including an acid leaving group. And

  According to the pattern forming method of the present invention, the polymer constituting the chemically amplified resist material includes, as a block polymer, an onium salt having an anion portion and a cation portion, and a group covalently bonded to a sulfonic acid group that is an anion portion. A first monomer unit and a second monomer unit including an acid leaving group are included. By this block polymer, the acid leaving groups that react during exposure are regularly arranged, so that the difference depending on the location of the acid elimination reaction is extremely small. Moreover, since an onium salt containing a sulfonic acid group is included, an acid is generated from the polymer itself. By these, the pattern which has a favorable shape with small roughness can be obtained.

  In the pattern forming method of the present invention, extreme ultraviolet rays, electron beams, ArF excimer laser light, or KrF excimer laser light can be used as exposure light.

  The dimension of the pattern to which the present invention is applied is 100 nm or less where the influence of roughness becomes significant. In particular, in the pattern of 50 nm or less, the influence of roughness is large, and the application value of the present invention is great.

  According to the chemically amplified resist material and the pattern forming method using the same according to the present invention, the roughness generated in the resist pattern can be reduced and a fine pattern having a good shape can be obtained.

(A)-(d) is sectional drawing which shows each process of the pattern formation method using the chemically amplified resist material which concerns on the 1st Embodiment of this invention. It is a top view which shows the resist pattern obtained by the pattern formation method which concerns on the 1st Embodiment of this invention. (A)-(d) is sectional drawing which shows each process of the pattern formation method using the chemically amplified resist material which concerns on the 2nd Embodiment of this invention. It is a top view which shows the resist pattern obtained by the pattern formation method which concerns on the 2nd Embodiment of this invention. (A)-(d) is sectional drawing which shows each process of the conventional pattern formation method. It is a top view which shows the resist pattern obtained by the conventional pattern formation method.

(First embodiment)
A chemically amplified resist material and a pattern forming method using the same according to a first embodiment of the present invention will be described with reference to FIGS. 1 (a) to 1 (d) and FIG.

  First, a positive chemically amplified resist material having the following composition is prepared.

Poly (triphenylsulfonium sulfonic acid styrene (50 mol%)-cyclohexylethyl methacrylate (50 mol%)) (block polymer) ... 2g
Triethanolamine (quencher) ... 0.002g
Propylene glycol monomethyl ether acetate (solvent) 20g
The general formula of the block polymer according to this embodiment is shown in [Chemical Formula 1].

次に、図１（ａ）に示すように、基板１０１の上に前記の化学増幅型レジスト材料を塗布し、続いて、９０℃の温度で６０秒間加熱して、厚さが６０ｎｍのレジスト膜１０２を形成する。

Next, as shown in FIG. 1A, the above-mentioned chemically amplified resist material is applied onto the substrate 101, and subsequently heated at a temperature of 90 ° C. for 60 seconds to form a resist film having a thickness of 60 nm. 102 is formed.

  Next, as shown in FIG. 1B, pattern exposure is performed by selectively irradiating the resist film 102 with exposure light composed of extreme ultraviolet rays having a numerical aperture (NA) of 0.25 and a wavelength of 13.5 nm. Do.

  Next, as shown in FIG. 1C, the resist film 102 subjected to pattern exposure is heated at a temperature of 105 ° C. for 60 seconds by a hot plate.

  Next, the heated resist film 102 is developed with a tetramethylammonium hydroxide developer having a concentration of 2.38 wt%, and as shown in FIGS. A resist pattern 102a having a line width of 30 nm is obtained.

  Thus, according to the first embodiment, the main polymer of the chemically amplified resist material constituting the resist film 102 has an onium salt having a cation portion (triphenylsulfonium) and an anion portion (sulfonic acid group). And a block polymer comprising a first monomer unit containing a group (phenyl group) covalently bonded to a sulfonic acid group which is an anion moiety, and a second monomer unit containing an acid leaving group (cyclohexylethyl group) Is used. For this reason, during the exposure shown in FIG. 1 (b), the acid leaving groups that react during the exposure are regularly arranged by the second monomer unit of the block polymer. Get smaller. Further, since the first monomer unit of the block polymer contains an onium salt containing a sulfonic acid group, an acid is generated from the polymer itself. Thereby, before the acid diffuses, an acid elimination reaction occurs due to the acid generated in and near the exposed portion of the resist film 102, so that the roughness of the pattern is reduced to about 3 nm with a standard deviation (3σ). A resist pattern 102a having a good shape can be obtained.

(Second Embodiment)
Hereinafter, a chemically amplified resist material and a pattern forming method using the same according to a second embodiment of the present invention will be described with reference to FIGS. 3 (a) to 3 (d) and FIG. 4.

  First, a positive chemically amplified resist material having the following composition is prepared.

Poly (diphenyliodonium sulfonic acid styrene (35mol%)-cyclopentylethyl methacrylate (65mol%)) (block polymer) ... 2g
Triethanolamine (quencher) ... 0.002g
Propylene glycol monomethyl ether acetate (solvent) 20g
The general formula of the block polymer according to this embodiment is shown in [Chemical Formula 2].

次に、図３（ａ）に示すように、基板２０１の上に前記の化学増幅型レジスト材料を塗布し、続いて、９０℃の温度で６０秒間加熱して、厚さが６０ｎｍのレジスト膜２０２を形成する。

Next, as shown in FIG. 3A, the chemically amplified resist material is applied on the substrate 201, and then heated at a temperature of 90 ° C. for 60 seconds to form a resist film having a thickness of 60 nm. 202 is formed.

  Next, as shown in FIG. 3B, pattern exposure is performed by selectively irradiating the resist film 202 with exposure light composed of extreme ultraviolet light having a numerical aperture (NA) of 0.25 and a wavelength of 13.5 nm. Do.

  Next, as shown in FIG. 3C, the resist film 202 subjected to pattern exposure is heated at a temperature of 105 ° C. for 60 seconds by a hot plate.

  Next, the heated resist film 202 is developed with a tetramethylammonium hydroxide developer having a concentration of 2.38 wt%, and as shown in FIGS. A resist pattern 202a having a line width of 30 nm is obtained.

  Thus, according to the second embodiment, the main polymer of the chemically amplified resist material constituting the resist film 202 has an onium salt having a cation part (diphenyliodonium) and an anion part (sulfonic acid group), And a block polymer comprising a first monomer unit containing a group (phenyl group) covalently bonded to a sulfonic acid group which is an anion portion, and a second monomer unit containing an acid leaving group (cyclopentylethyl group). Yes. For this reason, at the time of exposure shown in FIG. 3 (b), acid leaving groups that react at the time of exposure are regularly arranged by the second monomer unit of this block polymer. Get smaller. Further, since the first monomer unit of the block polymer contains an onium salt containing a sulfonic acid group, an acid is generated from the polymer itself. Thereby, before the acid diffuses, an acid elimination reaction occurs due to the acid generated in the exposed portion of the resist film 202 and in the vicinity thereof, so that the roughness of the pattern is reduced to about 2 nm with a standard deviation (3σ). A resist pattern 202a having a good shape can be obtained.

  In the first embodiment and the second embodiment, triphenylsulfonium and diphenyliodonium are used for the cation portion of the onium salt constituting the first monomer unit in the block polymer of the chemically amplified resist material. However, it is not limited thereto, and diphenyl (pt-butylphenyl) sulfonium or di (pt-butylphenyl) iodonium can be used.

  In addition, the cyclohexylethyl group and the cyclopentylethyl group are used as the acid leaving group constituting the second monomer unit in the block polymer of the chemically amplified resist material. However, the present invention is not limited thereto, and the acetal group, cyclohexylmethyl group, cyclopentyl A methyl group, a t-butyl group or a t-butyloxycarbonyl group can be used. In addition, when using an acetal group, 1-ethoxyethyl group, methoxymethyl group, 1-ethoxymethyl group, etc. can be used, for example.

  Further, xylene or ethylene can be used instead of styrene for the first monomer unit in the block polymer of the chemically amplified resist material, and acrylate can be used for the second monomer unit instead of methacrylate. it can.

  In addition, although extreme ultraviolet rays are used as the exposure light, an electron beam, ArF excimer laser light, or KrF excimer laser light can be used instead.

  The chemically amplified resist material and the pattern forming method using the same according to the present invention can realize a fine pattern having a good shape by reducing roughness generated in the resist pattern, and forming a fine pattern such as a manufacturing process of a semiconductor device. Etc. are useful.

101 Substrate 102 Resist Film 102a Resist Pattern 201 Substrate 202 Resist Film 202a Resist Pattern

Claims (11)

  A block comprising a first monomer unit having an onium salt having an anion part and a cation part and comprising a group covalently bonded to a sulfonic acid group being the anion part, and a second monomer unit comprising an acid leaving group A chemically amplified resist material comprising a polymer.   The chemical amplification type according to claim 1, wherein the cation part in the onium salt is triphenylsulfonium, diphenyl (pt-butylphenyl) sulfonium, diphenyliodonium or di (pt-butylphenyl) iodonium. Resist material.   The acid leaving group is an acetal group, a cyclohexylmethyl group, a cyclohexylethyl group, a cyclopentylmethyl group, a cyclopentylethyl group, a t-butyl group, or a t-butyloxycarbonyl group. The chemically amplified resist material described.   4. The chemically amplified resist material according to claim 3, wherein the acetal group is a 1-ethoxyethyl group, a methoxymethyl group, or a 1-ethoxymethyl group. The first monomer unit comprises styrene, xylene or ethylene;
The chemically amplified resist material according to claim 1, wherein the second monomer unit contains methacrylate or acrylate. Forming a resist film from a chemically amplified resist material on a substrate;
Performing pattern exposure by selectively irradiating the resist film with exposure light; and
Heating the resist film subjected to pattern exposure; and
And developing the heated resist film to form a resist pattern from the resist film,
The chemically amplified resist material includes an onium salt having an anion portion and a cation portion, a first monomer unit including a group covalently bonded to a sulfonic acid group that is the anion portion, and an acid leaving group. The pattern formation method characterized by including the block polymer containing 2 monomer units.   The pattern according to claim 6, wherein the cation part in the onium salt is triphenylsulfonium, diphenyl (pt-butylphenyl) sulfo-pnium, diphenyliodonium or di (pt-butylphenyl) iodonium. Forming method.   The pattern forming method according to claim 6, wherein the acid leaving group in the second monomer unit is an acetal group, a cyclohexylmethyl group, a cyclohexylethyl group, a cyclopentylmethyl group, or a cyclopentylethyl group. .   The pattern formation method according to claim 8, wherein the acetal group is a 1-ethoxyethyl group, a methoxymethyl group, or a 1-ethoxymethyl group. The first monomer unit comprises styrene, xylene or ethylene;
The pattern forming method according to claim 6, wherein the second monomer unit includes methacrylate or acrylate.   The pattern forming method according to claim 6, wherein the exposure light is extreme ultraviolet light, electron beam, ArF excimer laser light, or KrF excimer laser light.

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