JP4284132B2 - Pattern formation method - Google Patents

Description

  The present invention relates to a pattern forming method used in a semiconductor device manufacturing process or the like.

  In recent years, in the manufacturing process of a semiconductor device, the resolution of a resist pattern by lithography technology has been further miniaturized as the degree of integration of semiconductor elements has improved. In particular, a resist pattern having an opening (hole) for forming a contact hole has a reduced contrast by a conventional photolithography method, and it has become difficult to obtain a desired shape.

  Therefore, as a method for forming a fine contact hole pattern by photolithography, a water-soluble film containing a crosslinking agent is formed so as to cover the formed resist pattern, and heat is applied by the acid remaining in the unexposed portion of the resist pattern. A method of causing a crosslinking reaction with a water-soluble film as a catalyst to reduce (shrink) the opening diameter of the contact hole pattern has been proposed (for example, see Non-Patent Document 1).

  Hereinafter, a pattern forming method using a conventional chemical shrink method will be described with reference to FIGS.

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

Poly (2-methyl-2adamantyl acrylate (50mol%)-mevalonic lactone methacrylate (50mol%)) (base polymer) ... …………………………………………………… 2g
Triphenylsulfonium nonaflate (acid generator) …………………… 0.06g
Propylene glycol monomethyl ether acetate (solvent) ……………… 20g
Next, as shown in FIG. 14A, the chemically amplified resist material is applied onto the substrate 1 to form a resist film 2 having a thickness of 0.4 μm.

  Next, as shown in FIG. 14B, pattern exposure is performed by irradiating the resist film 2 with the exposure light 3 through the mask 4 by an ArF excimer laser scanner having a numerical aperture of 0.60.

  Next, as shown in FIG. 14C, post-exposure heating (PEB) is performed for 90 seconds at a temperature of 105 ° C. on the resist film 2 subjected to pattern exposure.

  Next, as shown in FIG. 14 (d), development is performed for 60 seconds with a 2.38 wt% tetramethylammonium hydroxide developer (alkaline developer) to form the opening diameter of the unexposed portion of the resist film 2. The initial resist pattern 2a having a thickness of 0.20 μm is obtained.

  Next, as shown in FIG. 15A, a water-soluble film 5 containing a crosslinking agent having the following composition is formed on the substrate 1 over the entire surface including the initial resist pattern 2a by spin coating. .

Polyvinyl alcohol (base polymer) …………………………… 2g
2,4,6-Tris (methoxymethyl) amino-1,3,5-s-triazine (crosslinking agent) ... 0.2g
Water (solvent) …………………………………………………………………………………… 30 g
Next, as shown in FIG. 15B, the formed water-soluble film 5 is heated at a temperature of 130 ° C. for 60 seconds to form the side wall portion of the opening in the initial resist pattern 2a and the side wall. The water-soluble film 5 in contact with the part is subjected to a crosslinking reaction.

Next, as shown in FIG. 15C, by removing the unreacted portion with the initial resist pattern 2a in the water-soluble film 5 with pure water 6, as shown in FIG. A resist pattern 7 having an opening diameter of 0.15 μm can be obtained, which is composed of the pattern 2a and the remaining portion 5a formed by crosslinking reaction with the opening side wall of the initial resist pattern 2a in the water-soluble film 5. Thus, the opening diameter of the resist pattern 7 is reduced from 0.20 μm of the initial resist pattern 2a to 0.15 μm.
T.Ishibashi et al., "Advanced Micro-Lithography Process with Chemical Shrink Technology", Jpn. J. Appl. Phys. Vol.40. 2001. pp.419-425 Japanese Patent Laid-Open No. 10-73927

  However, as shown in FIG. 15D, there is a problem in that the residue 5b is generated at the bottom of the opening of the obtained resist pattern 7 without completely removing the water-soluble film 5. As described above, when the residue 5b is generated in the resist pattern 7 from which the reduced pattern is obtained, the pattern shape of the member to be etched becomes defective in the subsequent etching process, which becomes a serious problem in the manufacture of the semiconductor device. Although a positive chemically amplified resist material is used for the resist film 2, a residue is generated even if a negative chemically amplified resist material is used.

  Therefore, in the defective resist pattern 7 in which such a residue 5b is generated, the shape of the pattern obtained in the member to be etched is also defective, so that productivity and yield in the manufacturing process of the semiconductor device are reduced. Problems arise.

  In view of the above, an object of the present invention is to improve the shape of a resist pattern obtained by a chemical shrink method.

  The inventors of the present application have conducted various studies to reliably remove the unreacted portion of the water-soluble film that shrinks the initial resist pattern in the resist pattern obtained by the chemical shrink method. A first finding has been obtained that when the liquid for removing the portion is replaced with pure water to be an alkaline aqueous solution, the water-soluble film can be easily and reliably removed. This is presumably because the aqueous alkali solution has higher solubility in the water-soluble film containing the crosslinking agent than pure water.

The inventors of the present invention can also generate a gap at a molecular level in a polymer constituting the water-soluble film by adding an alicyclic compound to the water-soluble film containing a crosslinking agent. As a result, the water-soluble film A second finding has been obtained that the solution for removing water penetrates into the gaps, and unreacted portions of the water-soluble film can be reliably removed.

  In addition, when a plasticizer that imparts plasticity to a water-soluble film containing a crosslinking agent is brought into contact with the water-soluble film, the water-soluble film becomes brittle and the permeability of the liquid at the time of removing the water-soluble film is improved. The third knowledge that the residue of the conductive film can be prevented has been obtained.

  In addition, by exposing a water-soluble film containing a cross-linking agent to plasma, the water-soluble film becomes weak and the liquid permeability when removing the water-soluble film is improved, thereby preventing the residue of the water-soluble film. The fourth knowledge is obtained.

  The present invention has been made based on these findings, and it is possible to prevent the residue of the water-soluble film provided for shrinking the initial resist pattern from occurring. Specifically, it is realized by the following method.

  A first pattern forming method according to the present invention includes a step of forming a resist film on a substrate, a step of selectively irradiating the resist film with exposure light to perform pattern exposure, and a resist film subjected to pattern exposure And developing a first resist pattern by performing development on the substrate, and a water-soluble film containing a crosslinking agent that crosslinks the material constituting the first resist pattern over the entire surface including the first resist pattern on the substrate Forming a water-soluble film, heating the water-soluble film, cross-linking the water-soluble film and portions of the first resist pattern that contact each other on the side surfaces of the first resist pattern, and using an aqueous alkaline solution By removing the unreacted portion with the first resist pattern in the conductive film, the water-soluble film remains on the side surface from the first resist pattern. And a step of forming a second resist pattern made.

  According to the first pattern formation method, when an unreacted portion of the water-soluble film cross-linked with the first resist pattern is removed, an alkaline aqueous solution whose solubility in the water-soluble film is higher than that of pure water is used. Since the unreacted portion can be reliably removed, the residue of the water-soluble film does not occur in the second resist pattern. As a result, the water-soluble film remains on the side surface of the first resist pattern, and the opening diameter or space width is reduced. The shape of the (shrinked) second resist pattern is improved.

  Here, the weight concentration of the alkaline aqueous solution is preferably about several wt% to 50 wt%. More preferably, it is not more than one-half (= about 1.20 wt%) of the weight concentration (2.38 wt%) of a normal alkaline developer, and furthermore, one-tenth (= About 0.24 wt%) is preferable.

  A second pattern forming method according to the present invention includes a step of forming a resist film on a substrate, a step of selectively irradiating the resist film with exposure light to perform pattern exposure, and a resist film subjected to pattern exposure. And developing a first resist pattern by cross-linking, and a cross-linking agent and an alicyclic compound that cross-links the material constituting the first resist pattern over the entire surface including the first resist pattern on the substrate. A step of forming a water-soluble film containing water, a step of cross-linking the water-soluble film and portions of the first resist pattern that contact each other on the side surface of the first resist pattern by heating the water-soluble film, By removing the unreacted portion of the film with the first resist pattern with a liquid, a water-soluble film remains on the side surface from the first resist pattern. And a step of forming a second resist pattern made.

  According to the second pattern formation method, since the alicyclic compound is included in the water-soluble film that reduces the pattern opening diameter or space width, the molecular-level gaps are included in the water-soluble polymer constituting the water-soluble film. Occurs. As a result, when the unreacted portion of the water-soluble film cross-linked with the first resist pattern is removed by the liquid, the permeability of the liquid to the water-soluble film is improved. Since it can be surely removed, the residue of the water-soluble film does not occur in the second resist pattern. As a result, the water-soluble film remains on the side surface of the first resist pattern, and the opening diameter or space width of the second resist is reduced. The pattern shape is improved.

  A third pattern forming method according to the present invention includes a step of forming a resist film on a substrate, a step of selectively irradiating the resist film with exposure light to perform pattern exposure, and a resist film subjected to pattern exposure And developing a first resist pattern by performing development on the substrate, and a water-soluble film containing a crosslinking agent that crosslinks the material constituting the first resist pattern over the entire surface including the first resist pattern on the substrate Forming a water-soluble film, heating the water-soluble film, cross-linking the water-soluble film and a portion of the first resist pattern that are in contact with each other on the side surface of the first resist pattern, and water-soluble after the crosslinking reaction The step of bringing a solution containing a plasticizer for imparting plasticity to the film into contact with the water-soluble film and the unreacted portion of the water-soluble film with the first resist pattern are removed by liquid. By water-soluble film on the side surface of the first resist pattern and a step of forming a second resist pattern comprising the remaining.

  According to the third pattern forming method, the water-soluble film is weakened by bringing a solution containing a plasticizer that imparts plasticity to the water-soluble film after the crosslinking reaction into contact with the water-soluble film. Since the unreacted portion of the first resist pattern can be surely removed, no residue of the water-soluble film is generated in the second resist pattern. As a result, the water-soluble film remains on the side surface of the first resist pattern and the opening diameter or space width is reduced. The reduced shape of the second resist pattern is improved.

  The amount of plasticizer added to the water-soluble film is preferably about several wt%.

  A fourth pattern forming method according to the present invention includes a step of forming a resist film on a substrate, a step of selectively irradiating the resist film with exposure light to perform pattern exposure, and a resist film subjected to pattern exposure. And developing a first resist pattern by performing development on the substrate, and a water-soluble film containing a crosslinking agent that crosslinks the material constituting the first resist pattern over the entire surface including the first resist pattern on the substrate A step of contacting the water-soluble film with a solution containing a plasticizer that imparts plasticity to the water-soluble film, and heating the water-soluble film in contact with the solution containing the plasticizer, A step of cross-linking the portions of the first resist pattern that contact each other on the side surfaces of the first resist pattern, and an unreacted portion of the water-soluble film with the first resist pattern By removing the body, the water-soluble film on the side surface of the first resist pattern and a step of forming a second resist pattern comprising the remaining.

  According to the fourth pattern formation method, after the water-soluble film is formed, the water-soluble film is weakened by bringing a solution containing a plasticizer that gives plasticity to the formed water-soluble film into contact with the water-soluble film. Since the unreacted portion of the water-soluble film can be surely removed by the liquid, a residue of the water-soluble film does not occur in the second resist pattern. As a result, the water-soluble film remains on the side surface of the first resist pattern and is opened. The shape of the second resist pattern having a reduced aperture or space width is improved.

  A fifth pattern forming method according to the present invention includes a step of forming a resist film on a substrate, a step of selectively irradiating the resist film with exposure light to perform pattern exposure, and a resist film subjected to pattern exposure. And developing a first resist pattern by performing development on the substrate, and a water-soluble film containing a crosslinking agent that crosslinks the material constituting the first resist pattern over the entire surface including the first resist pattern on the substrate Forming a water-soluble film, heating the water-soluble film, cross-linking the water-soluble film and a portion of the first resist pattern that are in contact with each other on the side surface of the first resist pattern, and water-soluble after the crosslinking reaction By removing the unreacted portion between the step of bringing the plasma into contact with the film and the first resist pattern in the water-soluble film with a liquid, the first resist pattern is obtained. Water-soluble film on a sidewall of the opening from over emissions is a step of forming a second resist pattern comprising the remaining.

  According to the fifth pattern forming method, since the water-soluble film is weakened by bringing the plasma into contact with the water-soluble film that has undergone the crosslinking reaction, the unreacted portion of the water-soluble film can be reliably removed by the liquid. The residue of the water-soluble film does not occur in the second resist pattern. As a result, the shape of the second resist pattern in which the water-soluble film remains on the side surface of the first resist pattern and the opening diameter or space width is reduced is good. Become.

  In the second to fifth pattern formation methods, it is preferable to use water or an alkaline aqueous solution as the liquid for removing the unreacted portion of the water-soluble film.

  According to the pattern forming method of the present invention, since the shape of the second resist pattern in which the opening diameter or the space width in the first resist pattern is reduced becomes good, the film to be processed etched using the second resist pattern The pattern shape is also good.

(First embodiment)
A pattern forming method according to the first embodiment of the present invention will be described with reference to FIGS. 1 (a) to 1 (d) and FIGS. 2 (a) to 2 (d).

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

Poly (2-methyl-2adamantyl acrylate (50mol%)-mevalonic lactone methacrylate (50mol%)) (base polymer) ... …………………………………………………… 2g
Triphenylsulfonium nonaflate (acid generator) …………………… 0.06g
Propylene glycol monomethyl ether acetate (solvent) ……………… 20g
Next, as shown in FIG. 1A, the chemically amplified resist material is applied onto the substrate 101 to form a resist film 102 having a thickness of 0.4 μm.

  Next, as shown in FIG. 1B, pattern exposure is performed by irradiating the resist film 102 with exposure light 103 from an ArF excimer laser scanner having a numerical aperture NA of 0.60 through a mask 104.

Next, as shown in FIG. 1 (c), the resist film 102 is baked, for example, a hot plate by you row a post-exposure for 90 seconds heating (PEB) at a temperature of 105 ° C..

  Next, as shown in FIG. 1 (d), development is performed for 60 seconds with a 2.38 wt% tetramethylammonium hydroxide developer (alkaline developer) to form an unexposed portion of the resist film 102. For example, a first resist pattern 102b for forming a contact hole and having an opening 102a having an opening diameter of 0.20 μm is obtained.

  Next, as shown in FIG. 2A, a water-soluble film 105 containing a cross-linking agent having the following composition is formed on the entire surface including the first resist pattern 102b on the substrate 101 by spin coating. To do.

Polyvinyl alcohol (base polymer) …………………………… 2g
2,4,6-Tris (methoxymethyl) amino-1,3,5-s-triazine (crosslinking agent) ... 0.2g
Water (solvent) …………………………………………………………………………………… 30 g
Next, as shown in FIG. 2 (b), the formed water-soluble film 105 is heated at a temperature of 130 ° C. for 60 seconds, and the side walls of the openings 102a in the first resist pattern 102b are formed. The water-soluble film 105 in contact with the side wall is subjected to a crosslinking reaction. Here, the water-soluble film 105 reacts only with the side wall portion of the opening 102a of the first resist pattern 102b because the upper surface of the first resist pattern 102b is an unexposed portion where the exposure light 103 is not irradiated. This is because no acid remains from 102.

  Next, as shown in FIG. 2C, an alkaline aqueous solution 106 in which about 0.24 wt% of tetramethylammonium hydroxide is added to pure water is used to form an undissolved portion with the first resist pattern 102b in the water-soluble film 105. The reaction part is removed. Thus, as shown in FIG. 2D, the first resist pattern 102b and the upper side wall portion 105a of the opening 102a of the first resist pattern 102b in the water-soluble film 105 are formed, and the opening width of the opening 102a is 0. Thus, the second resist pattern 107 reduced to 15 μm can be obtained. At this time, the residue of the water-soluble film 105 does not occur at the bottom of the opening 102a.

  As described above, according to the first embodiment, when the unreacted portion of the water-soluble film 105 that shrinks the opening diameter of the opening 102a of the first resist pattern 102b is removed, the solubility in the water-soluble film 105 is pure. Since an alkaline aqueous solution higher than water, for example, the alkaline aqueous solution 106 having a lower concentration than the alkali concentration of a commonly used alkaline developer, is used, the unreacted portion of the water-soluble film 105 is sufficiently dissolved in the alkaline aqueous solution 106. As a result, generation of residues of the water-soluble film 105 can be prevented, so that the shape of the second resist pattern 107 is improved.

  The concentration of the alkaline aqueous solution 106 is preferably about one-half that of a normal alkaline developer, that is, 1.20 wt% or less. Further, the concentration is about one-tenth that of a normal alkaline developer (0.24 wt. %) Is preferred.

  Further, as the alkaline aqueous solution 106, tetraethylammonium hydroxide aqueous solution, tetrabutylammonium hydroxide aqueous solution, or choline aqueous solution can be used instead of tetramethylammonium hydroxide.

(Second Embodiment)
A pattern forming method according to the second embodiment of the present invention will be described with reference to FIGS. 3 (a) to 3 (d) and FIGS. 4 (a) to 4 (d).

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

Poly (2-methyl-2adamantyl acrylate (50mol%)-mevalonic lactone methacrylate (50mol%)) (base polymer) ... …………………………………………………… 2g
Triphenylsulfonium nonaflate (acid generator) …………………… 0.06g
Propylene glycol monomethyl ether acetate (solvent) ……………… 20g
Next, as shown in FIG. 3A, the chemically amplified resist material is applied on the substrate 201 to form a resist film 202 having a thickness of 0.4 μm.

  Next, as shown in FIG. 3B, pattern exposure is performed by irradiating the resist film 202 with exposure light 203 from an ArF excimer laser scanner having a numerical aperture NA of 0.60 through a mask 204.

  Next, as shown in FIG. 3C, post-exposure heating (PEB) for 90 seconds is performed on the resist film 202 subjected to pattern exposure, for example, at a temperature of 105 ° C. using a hot plate.

  Next, as shown in FIG. 3 (d), development is performed with 2.38 wt% tetramethylammonium hydroxide developer (alkaline developer) for 60 seconds to form an unexposed portion of the resist film 202. For example, a first resist pattern 202b for forming a contact hole and having an opening 202a having an opening diameter of 0.20 μm is obtained.

  Next, as shown in FIG. 4A, a cross-linking agent and an adamantanol which is an alicyclic compound having the following composition are formed on the entire surface including the first resist pattern 202b on the substrate 201 by spin coating. A water-soluble film 205 containing is formed.

Polyvinyl alcohol (base polymer) …………………………… 2g
2,4,6-Tris (methoxymethyl) amino-1,3,5-s-triazine (crosslinking agent) ... 0.2g
Adamantanol (cycloaliphatic compound) ……………… 0.05g
Water (solvent) …………………………………………………………………………………… 30 g
Next, as shown in FIG. 4B, the formed water-soluble film 205 is heated at a temperature of 130 ° C. for 60 seconds to form the side wall portion of the opening 202a in the first resist pattern 202b. The water-soluble film 205 in contact with the side wall is subjected to a crosslinking reaction.

  Next, as shown in FIG. 4C, the unreacted portion of the water-soluble film 205 with the first resist pattern 202b is removed using pure water 206. As a result, as shown in FIG. 4D, the first resist pattern 202b and the sidewall upper portion 205a of the opening 202a in the water-soluble film 205 are formed, and the opening width of the opening 202a is reduced to 0.15 μm. 2 A resist pattern 207 is obtained. At this time, the residue of the water-soluble film 205 does not occur at the bottom of the opening 202a.

  Thus, according to the second embodiment, an alicyclic compound that improves the permeability of pure water 206 is added to the water-soluble film 205 that shrinks the opening diameter of the opening 202a of the first resist pattern 202b. Therefore, when the unreacted portion of the water-soluble film 205 is removed, the pure water 206 sufficiently penetrates into the unreacted portion of the water-soluble film 205. For this reason, the pure water 206 sufficiently permeates the unreacted portion of the water-soluble film 205 and the unreacted portion is easily removed, so that the generation of the residue of the water-soluble film 205 can be prevented. The shape of the second resist pattern 207 is improved.

  The alicyclic compound added to the water-soluble film 205 is not limited to adamantanol which is a derivative of adamantane. For example, norbornene or a derivative thereof, perhydroanthracene or a derivative thereof, cyclohexane or a derivative thereof, tricyclodecane or a derivative thereof Derivatives or adamantane can be used. Here, hydroxynorbornene can be used as the norbornene derivative, hydroxyperhydroanthracene can be used as the perhydroanthracene derivative, cyclohexanol can be used as the cyclohexane derivative, and tricyclodecane Hydroxytricyclodecane can be used as the derivative.

  Also in the second embodiment, when an alkaline aqueous solution, for example, an alkaline aqueous solution having a concentration lower than that of the alkaline developer is used for the pure water 206 for removing the water-soluble film 205, an unreacted portion of the water-soluble film 205 is more reliably detected. Can be removed.

(Third embodiment)
The pattern forming method according to the third embodiment of the present invention will be described below with reference to FIGS. 5 (a) to 5 (d), FIGS. 6 (a) to 6 (d) and FIG.

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

Poly (2-methyl-2adamantyl acrylate (50mol%)-mevalonic lactone methacrylate (50mol%)) (base polymer) ... …………………………………………………… 2g
Triphenylsulfonium nonaflate (acid generator) …………………… 0.06g
Propylene glycol monomethyl ether acetate (solvent) ……………… 20g
Next, as shown in FIG. 5A, the chemically amplified resist material is applied onto the substrate 301 to form a resist film 302 having a thickness of 0.4 μm.

  Next, as shown in FIG. 5B, pattern exposure is performed by irradiating the resist film 302 with exposure light 303 from an ArF excimer laser scanner having a numerical aperture NA of 0.60 through a mask 304.

Next, FIG. 5 (c), the resist film 302 is baked, for example, a hot plate by heating after exposure for 90 seconds at a temperature of 105 ° C. (PEB) will the row.

  Next, as shown in FIG. 5 (d), development is performed with a 2.38 wt% tetramethylammonium hydroxide developer (alkaline developer) for 60 seconds to form an unexposed portion of the resist film 302. For example, a first resist pattern 302b for forming a contact hole and having an opening 302a having an opening diameter of 0.20 μm is obtained.

  Next, as shown in FIG. 6A, a water-soluble film 305 containing a cross-linking agent having the following composition is formed on the entire surface including the first resist pattern 302b on the substrate 301 by spin coating. To do.

Polyvinyl alcohol (base polymer) …………………………… 2g
2,4,6-Tris (methoxymethyl) amino-1,3,5-s-triazine (crosslinking agent) ... 0.2g
Water (solvent) …………………………………………………………………………………… 30 g
Next, as shown in FIG. 6B, the formed water-soluble film 305 is heated at a temperature of 130 ° C. for 60 seconds so that the side wall of the opening 302a in the first resist pattern 302b The water-soluble film 305 in contact with the side wall portion is subjected to a crosslinking reaction.

  Next, as shown in FIG. 6 (c), a cyclohexanone solution 306 to which a plasticizer that imparts plasticity to the water-soluble film 305, for example, dinormal octyl phthalate having a concentration of 4 wt% is added by a paddle (liquid piling) method. By contacting with the water-soluble film 305 on the substrate 301 for 30 seconds, the film quality of the water-soluble film 505 is weakened to such an extent that the crosslinking reactivity is not lost. Note that the method of bringing the solution 306 into contact with the water-soluble film 305 is not limited to the paddle method, and a spray method in which the solution 306 is sprayed or a dip method in which the substrate 301 is immersed in the solution 306 may be used.

  Next, as shown in FIG. 6D, the unreacted portion of the water-soluble film 305 with the first resist pattern 302b is removed with pure water 307. Accordingly, as shown in FIG. 7, the second resist pattern is composed of the first resist pattern 302b and the upper side wall portion 305a of the opening 302a in the water-soluble film 305, and the opening width of the opening 302a is reduced to 0.15 μm. 308 is obtained. At this time, no residue of the water-soluble film 305 is generated at the bottom of the opening 302a.

  Thus, according to the third embodiment, after the water-soluble film 305 that shrinks the opening diameter of the opening 302a of the first resist pattern 302b is cross-linked with the first resist pattern 302b, the film quality of the water-soluble film 305 is obtained. Since the water-soluble film 305 is brought into contact with the cyclohexanone solution 306 to which a plasticizer that weakens the water is added, when the unreacted portion of the water-soluble film 305 is removed, the water-soluble film 305 whose film quality is weakened is not yet removed. The reaction part can be sufficiently dissolved even with pure water 307. For this reason, since the unreacted portion of the water-soluble film 305 is easily removed by the pure water 307, generation of residues of the water-soluble film 305 can be prevented, and as a result, the shape of the second resist pattern 308 is good. It becomes.

  Also in the third embodiment, when an alkaline aqueous solution, for example, an alkaline aqueous solution having a concentration lower than that of an alkaline developer is used for the pure water 307 from which the water-soluble film 305 is removed, an unreacted portion of the water-soluble film 305 is more reliably detected. Can be removed.

  In the third embodiment, di-normal octyl phthalate, which is a phthalate ester, is used as a plasticizer that imparts appropriate plasticity to the water-soluble film 305. However, the present invention is not limited to this, and adipate ester, sebacine Acid esters, adipic acid polyester series, dioctyl azelate, tricresyl phosphate, tributyl acetylcitrate, epoxidized soybean oil, trioctyl trimetate or chlorinated paraffin can be used.

  In addition to dinormal octyl phthalate, phthalate esters include, for example, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, diisononyl phthalate, dinonyl phthalate, diisodecyl phthalate Alternatively, butyl benzyl phthalate can be used. Further, for example, dioctyl adipate or diisononyl adipate can be used as the adipic acid ester. In addition, as the sebacic acid ester, for example, dibutyl sebacate or dioctyl sebacate can be used.

(Fourth embodiment)
Hereinafter, a pattern forming method according to a fourth embodiment of the present invention will be described with reference to FIGS. 8 (a) to 8 (d), FIGS. 9 (a) to 9 (d) and FIG.

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

Poly (2-methyl-2adamantyl acrylate (50mol%)-mevalonic lactone methacrylate (50mol%)) (base polymer) ... …………………………………………………… 2g
Triphenylsulfonium nonaflate (acid generator) …………………… 0.06g
Propylene glycol monomethyl ether acetate (solvent) ……………… 20g
Next, as shown in FIG. 8A, the chemically amplified resist material is applied on a substrate 401 to form a resist film 402 having a thickness of 0.4 μm.

  Next, as shown in FIG. 8B, pattern exposure is performed by irradiating the resist film 402 with exposure light 403 from an ArF excimer laser scanner having a numerical aperture NA of 0.60 through a mask 404.

Next, as shown in FIG. 8 (c), the resist film 402 is baked, for example, a hot plate by you row a post-exposure for 90 seconds heating (PEB) at a temperature of 105 ° C..

  Next, as shown in FIG. 8 (d), development is performed for 60 seconds with 2.38 wt% tetramethylammonium hydroxide developer (alkaline developer) to form an unexposed portion of the resist film 402. For example, a first resist pattern 402b for forming a contact hole and having an opening 402a having an opening diameter of 0.20 μm is obtained.

  Next, as shown in FIG. 9A, a water-soluble film 405 containing a cross-linking agent having the following composition is formed on the entire surface of the substrate 401 including the first resist pattern 402b by spin coating. To do.

Polyvinyl alcohol (base polymer) …………………………… 2g
2,4,6-Tris (methoxymethyl) amino-1,3,5-s-triazine (crosslinking agent) ... 0.2g
Water (solvent) …………………………………………………………………………………… 30 g
Next, as shown in FIG. 9 (b), by a paddle method, a tetrahydrofuran solution 406 to which a plasticizer that imparts plasticity to the water-soluble film 405, for example, dioctyl adipate having a concentration of 6 wt% is added to a substrate. By contacting with the water-soluble film 405 on 401 for 15 seconds, the film quality of the water-soluble film 405 is weakened to such an extent that the crosslinking reactivity is not lost. Note that the method of bringing the solution 406 into contact with the water-soluble film 405 is not limited to the paddle method, and a spray method in which the solution 406 is sprayed or a dip method in which the substrate 401 is immersed in the solution 406 may be used.

  Next, as shown in FIG. 9C, the water-soluble film 305 in contact with the solution 406 to which the plasticizer is added is heated at a temperature of 130 ° C. for 60 seconds, so that the first resist pattern 402b. The side wall portion of the opening 402a and the water-soluble film 405 in contact with the side wall portion are subjected to a crosslinking reaction.

  Next, as shown in FIG. 9D, the unreacted portion of the water-soluble film 405 with the first resist pattern 402b is removed with pure water 407. Thus, as shown in FIG. 10, the second resist pattern is composed of the first resist pattern 402b and the upper side wall portion 405a of the opening 402a in the water-soluble film 405, and the opening width of the opening 402a is reduced to 0.15 μm. 408 is obtained. At this time, a residue of the water-soluble film 405 does not occur at the bottom of the opening 402a.

  As described above, according to the fourth embodiment, the water-soluble film 405 that shrinks the opening diameter of the opening 402a of the first resist pattern 402b is formed on the first resist pattern 402b, and then the water-soluble film 405 is formed. Since the water-soluble film 405 is brought into contact with the tetrahydrofuran solution 406 to which a plasticizer that weakens the film quality is added, when the unreacted portion of the water-soluble film 405 is removed, the water-soluble film 405 having a weak film quality is removed. Unreacted parts can be sufficiently dissolved even with pure water 407. For this reason, since the unreacted portion of the water-soluble film 405 is easily removed by the pure water 407, generation of a residue of the water-soluble film 405 can be prevented, and as a result, the shape of the second resist pattern 408 is good. It becomes.

  Even in the fourth embodiment, when an alkaline aqueous solution, for example, an alkaline aqueous solution having a concentration lower than that of an alkaline developer is used for the pure water 407 from which the water-soluble film 405 is removed, an unreacted portion of the water-soluble film 405 can be more reliably obtained. Can be removed.

  In the fourth embodiment, dioctyl adipate, which is an adipate, is used as the plasticizer. However, the present invention is not limited to this. Phthalate ester, sebacic acid ester, adipic acid polyester, dioctyl azelate, phosphorus Tricresyl acid, tributyl acetyl citrate, epoxidized soybean oil, trioctyl trimetate or chlorinated paraffin can be used.

  In this case, the phthalate ester includes, for example, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, di-normal octyl phthalate, diisononyl phthalate, dinonyl phthalate, diisodecyl phthalate or Butylbenzyl phthalate can be used. In addition to dioctyl adipate, for example, diisononyl adipate can be used as the adipic acid ester. In addition, as the sebacic acid ester, for example, dibutyl sebacate or dioctyl sebacate can be used.

(Fifth embodiment)
Hereinafter, a pattern forming method according to the fifth embodiment of the present invention will be described with reference to FIGS. 11 (a) to 11 (d), FIGS. 12 (a) to 12 (d) and FIG.

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

Poly (2-methyl-2adamantyl acrylate (50mol%)-mevalonic lactone methacrylate (50mol%)) (base polymer) ... …………………………………………………… 2g
Triphenylsulfonium nonaflate (acid generator) …………………… 0.06g
Propylene glycol monomethyl ether acetate (solvent) ……………… 20g
Next, as shown in FIG. 11A, the chemically amplified resist material is applied on a substrate 501 to form a resist film 502 having a thickness of 0.4 μm.

  Next, as shown in FIG. 11B, pattern exposure is performed by irradiating the resist film 502 with exposure light 503 through a mask 504 by an ArF excimer laser scanner having a numerical aperture NA of 0.60.

Next, as shown in FIG. 11 (c), the resist film 502 is baked, for example, a hot plate by you row a post-exposure for 90 seconds heating (PEB) at a temperature of 105 ° C..

  Next, as shown in FIG. 11 (d), development is performed for 60 seconds with a 2.38 wt% tetramethylammonium hydroxide developer (alkaline developer) to form an unexposed portion of the resist film 502. For example, a first resist pattern 502b for forming a contact hole and having an opening 502a having an opening diameter of 0.20 μm is obtained.

  Next, as shown in FIG. 12A, a water-soluble film 505 containing a crosslinking agent having the following composition is formed on the entire surface of the substrate 501 including the first resist pattern 502b by spin coating. To do.

Polyvinyl alcohol (base polymer) …………………………… 2g
2,4,6-Tris (methoxymethyl) amino-1,3,5-s-triazine (crosslinking agent) ... 0.2g
Water (solvent) …………………………………………………………………………………… 30 g
Next, as shown in FIG. 12B, the formed water-soluble film 505 is heated at a temperature of 130 ° C. for 60 seconds to form the side wall portion of the opening 502a in the first resist pattern 502b. The water-soluble film 505 in contact with the side wall is subjected to a crosslinking reaction.

Next, as shown in FIG. 12C, the film quality of the water-soluble film 505 is cross-linked by exposing it to a plasma 506 made of trifluoromethane (CHF ₃ ) having a pressure of 1.33 Pa and an output of 50 W for 10 seconds. Vulnerability to the extent that it is not lost

  Next, as shown in FIG. 12D, the unreacted portion of the water-soluble film 505 with the first resist pattern 502b is removed with pure water 507. Accordingly, as shown in FIG. 13, the second resist pattern is composed of the first resist pattern 502b and the upper side wall portion 505a of the opening 502a in the water-soluble film 505, and the opening width of the opening 502a is reduced to 0.15 μm. Get 508. At this time, a residue of the water-soluble film 505 does not occur at the bottom of the opening 502a.

  As described above, according to the fifth embodiment, the water-soluble film 505 that shrinks the opening diameter of the opening 502a of the first resist pattern 502b is cross-linked with the first resist pattern 502b, and then the film quality of the water-soluble film 505 is reached. Since the water-soluble film 505 is exposed to plasma so as to weaken the water, the unreacted part of the water-soluble film 505 whose film quality is weakened is removed with pure water 507 when the unreacted part of the water-soluble film 505 is removed. It will be able to dissolve sufficiently. For this reason, since the unreacted portion of the water-soluble film 505 is easily removed by the pure water 507, the generation of the residue of the water-soluble film 505 can be prevented, and as a result, the shape of the second resist pattern 508 is good. It becomes.

  Also in the fifth embodiment, when an alkaline aqueous solution, for example, an alkaline aqueous solution having a concentration lower than that of an alkaline developer is used for the pure water 507 from which the water-soluble film 505 is removed, an unreacted portion of the water-soluble film 505 is more reliably obtained. Can be removed.

  Further, as plasma that weakens the water-soluble film 505, fluorine-based plasma, chlorine-based plasma, or oxygen-based plasma can be used.

In this case, instead of trifluoromethane (CHF ₃ ), carbon tetrafluoride (CF ₄ ), difluoromethane (CH ₂ F ₂ ), or monofluoromethane (CH ₃ F) may be used for the fluorine-based plasma. it can.

In addition, carbon tetrachloride (CCl ₄ ), trichloromethane (CHCl ₃ ), dichloromethane (CH ₂ Cl ₂ ), or monochloromethane (CH ₃ Cl) can be used for the chlorine plasma.

In this case, oxygen (O ₂ ) can be used for the oxygen-based plasma.

  In the first to fifth embodiments, the second resist pattern is not limited to the opening pattern for forming the contact hole, and prevents the residue of the water-soluble film generated in the space portion where the line portion is adjacent. It is also effective in some cases.

  In the first to fifth embodiments, a positive chemically amplified resist is used as the resist material constituting each first resist pattern. However, the resist material is not limited to the chemically amplified resist, and the first resist pattern Any resist material may be used as long as acid is generated on the side wall of the pattern after formation. Further, the resist is not limited to a positive resist, and may be a negative resist.

In the first to fifth embodiments, 2,4,6-tris (methoxymethyl) amino-1, a crosslinking agent added to the water-soluble film that shrinks the opening diameter of the opening of each first resist pattern 3,5-s-triazine was used, but instead, 2,4,6-tris (trihydroxymethyl) amino-1,3,5-s-triazine , 2,4,6-tris (ethoxy) Methyl) amino-1,3,5-s-triazine, tetramethoxymethylglycolurea, tetramethoxymethylurea, 1,3,5-tris (methoxymethoxy) benzene or 1,3,5-tris (isopropoxymethoxy) Benzene can be used.

  Moreover, polyvinyl alcohol or polyvinyl pyrrolidone can be used for each water-soluble film.

In the first to fifth embodiments, the exposure light of each first resist pattern is not limited to ArF excimer laser, and KrF excimer laser or F ₂ laser can be used.

  The pattern forming method according to the present invention has an effect that the shape of a resist pattern formed using a chemical shrink method can be improved, and is useful as a pattern forming method used in a semiconductor device manufacturing process or the like. .

(A)-(d) is sectional drawing of the order of a process which shows the pattern formation method which concerns on the 1st Embodiment of this invention. (A)-(d) is sectional drawing of the order of a process which shows the pattern formation method which concerns on the 1st Embodiment of this invention. (A)-(d) is sectional drawing of the order of a process which shows the pattern formation method which concerns on the 2nd Embodiment of this invention. (A)-(d) is sectional drawing of the order of a process which shows the pattern formation method which concerns on the 2nd Embodiment of this invention. (A)-(d) is sectional drawing of the order of a process which shows the pattern formation method which concerns on the 3rd Embodiment of this invention. (A)-(d) is sectional drawing of the order of a process which shows the pattern formation method which concerns on the 3rd Embodiment of this invention. It is sectional drawing of 1 process which shows the pattern formation method which concerns on the 3rd Embodiment of this invention. (A)-(d) is sectional drawing of the order of a process which shows the pattern formation method which concerns on the 4th Embodiment of this invention. (A)-(d) is sectional drawing of the order of a process which shows the pattern formation method which concerns on the 4th Embodiment of this invention. It is sectional drawing of 1 process which shows the pattern formation method which concerns on the 4th Embodiment of this invention. (A)-(d) is sectional drawing of the order of a process which shows the pattern formation method which concerns on the 5th Embodiment of this invention. (A)-(d) is sectional drawing of the order of a process which shows the pattern formation method which concerns on the 5th Embodiment of this invention. It is sectional drawing of 1 process which shows the pattern formation method which concerns on the 5th Embodiment of this invention. (A)-(d) is sectional drawing of the order of a process which shows the pattern formation method by the conventional chemical shrink method. (A)-(d) is sectional drawing of the order of a process which shows the pattern formation method by the conventional chemical shrink method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Substrate 102 Resist film 102a Opening part 102b First resist pattern 103 Exposure light 104 Mask 105 Water-soluble film 105a Water-soluble film side wall upper part 106 Alkaline aqueous solution 107 Second resist pattern 201 Substrate 202 Resist film 202a Opening part 202b First resist Pattern 203 Exposure light 204 Mask 205 Water-soluble film 205a to which alicyclic compound is added Water-soluble film upper side wall portion 206 Pure water 207 Second resist pattern 301 Substrate 302 Resist film 302a Opening 302b First resist pattern 303 Exposure light 304 Mask 305 Water-soluble film 305a Upper side wall portion 306 of water-soluble film Cyclohexanone solution 307 with plasticizer added Pure water 308 Second resist pattern 401 Substrate 402 Resist film 402a Opening 402b First Dist pattern 403 Exposure light 404 Mask 405 Water-soluble film 405a Water-soluble film side wall upper portion 406 Tetrahydrofuran solution 407 with plasticizer added Pure water 408 Second resist pattern 501 Substrate 502 Resist film 502a Opening 502b First resist pattern 503 Exposure light 504 Mask 505 Water-soluble film 505a Water-soluble film side wall upper portion 506 CHF ₃ plasma 507 Pure water 508 Second resist pattern

Claims (6)

Forming a resist film on the substrate;
A step of selectively irradiating the resist film with exposure light to perform pattern exposure;
Forming a first resist pattern by developing the resist film subjected to pattern exposure; and
Forming a water-soluble film containing a cross-linking agent that cross-links with a material constituting the first resist pattern over the entire surface including the first resist pattern on the substrate;
A step of causing a cross-linking reaction between portions of the water-soluble film and the first resist pattern that are in contact with each other on the side surface of the first resist pattern by heating the water-soluble film;
A second resist pattern in which the water-soluble film remains on the side surface of the first resist pattern by removing an unreacted portion of the water-soluble film with the first resist pattern using an alkaline aqueous solution. And forming a process ,
The pattern forming method , wherein the concentration of the alkaline aqueous solution is 1.20 wt% or less . The pattern forming method according to claim 1, wherein the resist film is a chemically amplified resist. The crosslinking agent is 2,4,6-tris (trihydroxymethyl) amino-1,3,5-s-triazine , 2,4,6-tris (methoxymethyl) amino-1,3,5-s- Triazine, 2,4,6-tris (ethoxymethyl) amino-1,3,5-s-triazine, tetramethoxymethylglycolurea, tetramethoxymethylurea, 1,3,5-tris (methoxymethoxy) benzene or 1 The pattern forming method according to claim 1, wherein the pattern is 1,3,5-tris (isopropoxymethoxy) benzene. The pattern forming method according to claim 1, wherein the water-soluble film is made of polyvinyl alcohol or polyvinyl pyrrolidone. The pattern forming method according to claim 1 , wherein the alkaline aqueous solution is a tetramethylammonium hydroxide aqueous solution, a tetraethylammonium hydroxide aqueous solution, a tetrabutylammonium hydroxide aqueous solution, or a choline aqueous solution. The pattern forming method according to claim 1, wherein the exposure light is an ArF excimer laser, a KrF excimer laser, or an F ₂ laser.

Images