JP2002184673A - Resist pattern formation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resist pattern formation method which restrains increase in cost, prevents lowering of process treatment capability and is superior in dimensional uniformity. SOLUTION: A first resist pattern 111 is formed in a semiconductor substrate 101. A third film is formed (112) on the first resist pattern 111. Heat treatment is carried out at 140 deg.C for 60 seconds, by using a hot plate 113. The first resist pattern 111 and the third film 112 are re-immersed in 2.38% tetramethyl ammonium hydroxyl water solution 114. Then, a second resist pattern 115 is formed. A desired resist pattern 115 is formed through the processes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for forming a resist pattern.

[0002]

2. Description of the Related Art Higher performance of semiconductor devices has been realized by miniaturization of elements. In order to make patterns finer, in lithography, the NA of a projection lens of a reduction projection exposure apparatus and the wavelength of an exposure light source have been continuously reduced. However, these methods require the use of newly developed equipment,
Moreover, the newly developed equipment is expensive. Therefore, if a finer pattern can be formed using existing equipment, a high-performance semiconductor device can be realized at lower cost.

For example, in 1997. Symp. on VL
SI Tech, P.M. 131-132, 1997. This method is a method of forming a fine pattern by narrowing a resist pattern formed by exposure at the time of dry etching for underlying processing.

[0004] IEDM. Tech. Dig, P .; 3
33-336, 1998.
(R esolution E nhancement L ithography A ssisted by C
there is hemical S hrink) and the method called. This is a method in which a coating film is formed after forming a resist pattern, then heat treatment is performed, and finally, a fine resist pattern is formed by immersion in an alkaline aqueous solution different from tetramethylammonium hydroxide (hereinafter referred to as TMAH). .

[0005]

However, in the above-described etching bias method, since the resist pattern is made finer by dry etching, it is strongly affected by dimensional variations at the time of dry etching, dimensional variations in the wafer surface, lot-to-lot variations. There was a problem that the dimensional uniformity was poor.

Further, the method called RELACS has a problem that a special developing equipment is required because a developing solution to be used is special, and the cost is increased. In addition, since many special processes are added to a normal lithography process, there is a problem that the process processing capability is greatly reduced. There is also a problem that the dimensional uniformity in the wafer surface is poor.

Therefore, it is difficult to form a fine resist pattern with high accuracy by the above two methods.

In view of the above, it is an object of the present invention to provide a method of forming a resist pattern which suppresses an increase in cost, prevents a reduction in processability, and has excellent dimensional uniformity.

[0009]

A first method of forming a resist pattern according to the present invention comprises the steps of forming a first resist pattern on a semiconductor substrate and applying a first film on the first resist pattern. Performing a heat treatment on the first resist pattern and the first film, and immersing the first resist pattern and the first film in an aqueous solution of tetramethylammonium hydroxide to form a second resist pattern It is characterized by consisting of.

In this method for forming a resist pattern, a solution for immersing the first resist pattern and the first film is an aqueous solution of tetramethylammonium hydroxide, and therefore does not require a dedicated developing solution.

In the first method for forming a resist pattern, the material for forming the resist pattern is more preferably a chemically amplified resist.

In the first method for forming a resist pattern, it is more preferable that the first film is made of a material containing a water-soluble film-forming component and a surfactant.

In the first method for forming a resist pattern, it is more preferable that the first film is made of a material containing a water-soluble film-forming component and a surfactant containing a sulfonate.

A second method for forming a resist pattern according to the present invention comprises the steps of: applying a resist on a semiconductor substrate;
Heat treating the resist, applying a second film on the resist, heat treating the second film, exposing the resist and the second film via a predetermined mask, Heat treating the resist and the second film, developing the resist and the second film to form a first resist pattern, and applying a third film on the first resist pattern A step of heat treating the first resist pattern and the third film, and a step of immersing the first resist pattern and the third film in an aqueous solution of tetramethylammonium hydroxide to form a second resist pattern. It is characterized by becoming.

In the second method for forming a resist pattern, it is more preferable to use the same material for the second film and the third film. In the second method for forming a resist pattern, the resist is preferably a chemically amplified resist. More preferred.

In the second resist pattern forming method, the heat treatment of the first resist pattern and the third film is more preferably performed at a heat treatment temperature of 80 ° C. to 160 ° C.

According to a third method of forming a resist pattern according to the present invention, a step of forming a first resist pattern on a semiconductor substrate, a step of heat-treating the first resist pattern, and a step of forming the first resist pattern into tetramethyl A step of forming a second resist pattern by immersion in an aqueous solution of ammonium hydroxide.

This method of forming a resist pattern does not require a step of forming a third film.

In the first, second and third resist pattern forming methods, the aqueous tetramethylammonium hydroxide solution is more preferably a 2.38% aqueous tetramethylammonium hydroxide solution.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for forming a resist pattern according to the present invention will be described with reference to the drawings. (First Embodiment) A method for forming a resist pattern according to a first embodiment of the present invention will be described below with reference to FIGS.

As shown in FIG. 1A, a semiconductor substrate 10
First, DUV42P-8 manufactured by Nissan Chemical Co., Ltd. is applied to a thickness of 0.080 μm as a lower antireflection film layer serving as the first film 102.

Next, as shown in FIG. 1B, the first film 102 is heated at 220.degree.
Heat treatment is performed in sec. The first film 102 is cross-linked by the high-temperature baking process.

Next, as shown in FIG.
As 04, a resist PEK-112A4 manufactured by Sumitomo Chemical Co., Ltd. is applied to a thickness of 0.485 μm.

Next, as shown in FIG.
04 at 90 ° C. for 90 seconds using a hot plate 105
Heat treatment is performed in c.

Next, as shown in FIG.
6 TSP manufactured by Tokyo Ohka Kogyo Co., Ltd.
-9A EX is applied to a thickness of 0.042 μm.

Next, as shown in FIG. 2F, the second film 106 is heated at 60 ° C. for 60 seconds by using a hot plate 107.
Heat treatment is performed in c.

Next, as shown in FIG. 2G, a Nikon stepper is used as an exposure apparatus, and the resist film 104 is irradiated with light through a mask 108 on which a predetermined pattern is formed.

Next, as shown in FIG. 3H, a heat treatment is performed on the resist film 104 using a hot plate 109 at 100 ° C. for 90 seconds.

Next, as shown in FIG.
04 is immersed in a 2.38% TMAH aqueous solution as a developing solution 110 (hereinafter referred to as development).

Next, as shown in FIG. 3J, a first resist pattern 111 is formed.

Next, as shown in FIG. 4K, a third film 112 is formed on the first resist pattern 111.
The material for forming the third film 112 is acidic, and has polyvinylpyrrolidone which is a water-soluble film-forming component as a main component;
Perfluorooctylsulfonic acid-monoethanolamine salt as a surfactant is an N-alkyl-2-pyrrolidone solvent.

Next, as shown in FIG. 4 (l), heat treatment is performed at 140 ° C. for 60 seconds using a hot plate 113.

Next, as shown in FIG.
2 is immersed again in a 2.38% TMAH aqueous solution 114.

Next, as shown in FIG. 4N, a second resist pattern 115 is formed.

As described above, the resist pattern 115 which is the object of the present invention is formed by the steps shown in FIGS. 1 (a) to 4 (n).

In the pattern forming method of the present invention, since the solution for immersing the third film 112 is TMAH as compared with the conventional RELACS, a finer pattern can be formed using existing equipment. Is possible. Therefore, a high-performance semiconductor device can be realized at lower cost.

As a material for forming the third film 112,
Water-soluble film-forming component: polyvinylpyrrolidone, fluorine-based surfactant: perfluorooctylsulfonic acid-monoethanolamine salt, solvent: a film containing N-octyl-2-pyrrolidone was used. As the forming component, for example, cellulose-based cellulose such as hydroxypropylmethylcellulose phthalate, hydroxypropylmethylcellulose acetate phthalate, hydroxypropylmethylcellulose acetate succinate, hydroxypropylmethylcellulose hexahydrophthalate, hydroxypropylmethylcellulose, hydroxypropylethylcellulose, carboxymethylcellulose, ethylcellulose and methylcellulose Coalescing, N,
N-dimethylaminopropyl methacrylamide, N, N
-Dimethylaminopropylacrylamide, N, N-dimethylacrylamide, N, N-diethylaminoethyl methacrylate, N-methylacrylamide, diacetoneacrylamide, acryloylmorpholine, acrylic acid-based polymer having acrylic acid as a monomer, polyvinyl Examples thereof include vinyl polymers such as alcohol and polyvinylpyrrolidone.

Further, as the fluorosurfactant, perfluoroheptanoic acid, perfluorooctanoic acid, perfluoropropylsulfonic acid, perfluoroheptanoic acid-
Ammonium salt, perfluorooctanoic acid-ammonium salt, perfluorooctylsulfonic acid-ammonium salt, perfluoroheptanoic acid-tetramethylammonium salt, perfluorooctylsulfonic acid-tetramethylammonium salt, perfluorooctanoic acid-monoethanol Amine salts and perfluorodecylsulfonic acid-monoethanolamine salts. Further, as a solvent, N-hexyl-2-pyrrolidone, N-heptyl-2
-Pyrrolidone, N-nonyl-2-pyrrolidone, N-decyl-2-pyrrolidone, N-undecyl-2-pyrrolidone, N-tridecyl-2-pyrrolidone, N-tetradecyl-2-pyrrolidone, N-heptyl-2-pyrrolidone ,
N-pentadecyl-2-pyrrolidone, N-hexadecyl-2-pyrrolidone and the like can be used.

In the present invention, it is preferable that the exposure light source used in the pattern formation processing of the resist film 104 uses a short exposure wavelength. The exposure wavelength includes, for example, a KrF excimer laser beam, an ArF excimer laser, and an F2 laser. (Second Embodiment) A method for forming a resist pattern according to a second embodiment of the present invention will be described below with reference to FIGS.

As shown in FIG. 5A, DUV42P-8 manufactured by Nissan Chemical Industries, Ltd. is applied to a thickness of 0.080 μm on the semiconductor substrate 201 as a lower anti-reflection film layer as the first film 202.

Next, as shown in FIG. 5B, the first film 202 is heated at 220 ° C. and 60 ° C. using a hot plate 203.
Heat treatment is performed in sec. The first film 202 is cross-linked by the high-temperature baking process.

Next, as shown in FIG.
As 04, a resist PEK-112A4 manufactured by Sumitomo Chemical Co., Ltd. is applied to a thickness of 0.485 μm.

Next, as shown in FIG. 5D, heat treatment of the resist is performed at 90 ° C. and 90 ° C. using a hot plate 205.
Heat treatment is performed in sec.

Next, as shown in FIG.
6 TSP manufactured by Tokyo Ohka Kogyo Co., Ltd.
-9A EX is applied to a thickness of 0.042 μm.

Next, as shown in FIG. 6F, a heat treatment is performed on the hot plate 207 at 60 ° C. for 60 seconds.

Next, as shown in FIG. 6G, a resist film 204 is irradiated with light through a mask 208 on which a predetermined pattern is formed by using a Nikon stepper as an exposure device.

Next, as shown in FIG. 7H, heat treatment is performed at 100 ° C. for 90 seconds using a hot plate 209.

Next, as shown in FIG.
04 is developed using a 2.38% TMAH aqueous solution as a developing solution 210.

Next, as shown in FIG. 7J, a first resist pattern 211 is formed.

Next, as shown in FIG. 8K, a third film 212 is formed on the first resist
TSP manufactured by Tokyo Ohka Kogyo Co., Ltd.
Spin-coat -9A EX at 2000 rpm.

Next, as shown in FIG. 8 (l), heat treatment is performed at 80 ° C. to 140 ° C. for 60 seconds using a hot plate 213.

Next, as shown in FIG.
2 is again immersed in a 2.38% TMAH aqueous solution 214.

Next, as shown in FIG. 8N, a second resist pattern 215 is formed.

As described above, the resist pattern 215 which is the object of the present invention is formed by the steps shown in FIGS. 5 (a) to 8 (n).

In the second embodiment, the second film 206 and the third
Film 212 is made of the same material, TSP-
9A EX was used. This material can form a uniform film on the first resist pattern 210, and shows acidity,
The third film 21 having the property of being soluble in alkali development
2 can be used. Therefore, since the same material and the same equipment can be used, a fine resist pattern can be formed at low cost.

FIG. 9 shows a line width-focus dependency graph. It can be seen that the depth of focus is improved as the heat treatment temperature is increased from 80 ° C. to 140 ° C. Moreover, it is also possible to form a fine line pattern by increasing the exposure amount by a usual method. In this case, there is a problem that the dimensional deviation of the resist pattern in the case where the focus deviation occurs as the pattern is miniaturized increases.
By using the method of the present invention, the size can be uniformly reduced, and a fine resist pattern can be formed while keeping the depth of focus.

Under the condition of the heat treatment at 140 ° C., it is possible to form a finer resist pattern with a line width of an isolated line of 148.5 nm and 115.6 nm using existing equipment. When the heat treatment temperature is low, sufficient pattern shrinkage can be realized, but the depth of focus is reduced. Conversely, when the temperature is too high (160 ° C. or more), problems such as formation of development residues and deformation due to heat dripping of the pattern occur. . Therefore, it is effective to set the heat treatment temperature to 80 to 160 ° C. When comparing the depth of focus, 80 ° C is 0.33μ
m, 0.42 μm at 120 ° C., 0.50 μm at 140 ° C.
By increasing the baking temperature, the depth of focus was improved. More preferably, the temperature is set to 120 to 140 ° C. (Third Embodiment) Hereinafter, a method for forming a resist pattern according to a third embodiment of the present invention will be described with reference to FIGS. 10 (a) to 13 (m).

As shown in FIG. 10A, the semiconductor substrate 30
1 is coated with DUV42P-8 (manufactured by Nissan Chemical Industries, Ltd.) to a thickness of 0.080 μm as a lower antireflection film layer serving as the first film 302.

Next, as shown in FIG. 10B, the first film 302 is heated at 220 ° C. for 6 hours using a hot plate 303.
Heat treatment is performed for 0 sec. The first film 302 is cross-linked by the high-temperature baking process.

Next, as shown in FIG. 11C, as a resist film 304, a resist PEK-112A4 manufactured by Sumitomo Chemical Co., Ltd.
Is applied to a thickness of 0.485 μm.

Next, as shown in FIG. 11D, the resist film 304 is
Heat treatment is performed in sec.

Next, as shown in FIG. 11E, as an upper anti-reflection film 306 as a second film, a TS manufactured by Tokyo Ohka Kogyo Co., Ltd.
P-9A EX is applied to a thickness of 0.042 μm.

Next, as shown in FIG. 11F, the second film 306 is heated at 60 ° C. for 60 seconds by using a hot plate 307.
Heat treatment is performed at ec.

Next, as shown in FIG. 12 (g), using a Nikon stepper as an exposure device, the resist film 304 is irradiated with light through a mask 308 on which a predetermined pattern is formed.

Next, as shown in FIG. 12H, a heat treatment is performed at 100 ° C. for 90 seconds using a hot plate 309.

Next, as shown in FIG. 12I, the resist film 304 is developed using a 2.38% TMAH aqueous solution as a developing solution 310.

Next, as shown in FIG. 13 (j), a first resist pattern 311 is formed.

Next, as shown in FIG. 13K, heat treatment is performed at 120 ° C. for 90 seconds using a hot plate 312.

Next, as shown in FIG. 13L, the first resist pattern 311 is immersed in a 2.38% TMAH aqueous solution 313.

Next, as shown in FIG. 13 (m), a second resist pattern 314 is formed.

As described above, the resist pattern 314 which is the object of the present invention is formed by the steps shown in FIGS. 10 (a) to 13 (m).

In the present embodiment, it is possible to form a fine pattern, and since there is no step of forming a third film as compared with the first embodiment, a highly accurate resist pattern can be formed. As well as high processing capability can be realized.

FIG. 14 shows the result of the method of forming a resist pattern according to the present embodiment in a line width-focus dependency graph. It was possible to form a finer pattern with a line width of the isolated line of 148.5 nm to 133.2 nm using the existing equipment. Also, it can be seen that the depth of focus is also increasing.

In this embodiment, the acid remaining in the unexposed area after development is used to increase the solubility of the unexposed area by heat treatment, reduce the size of the first resist pattern, and reduce the size of the second resist pattern. Is formed. Therefore, in order to form a resist pattern having excellent dimensional uniformity, FIG.
More preferably, the time interval from the step 3 (k) to the step of FIG. 13 (l) is performed within 2 hours.

[0075]

According to the first method for forming a resist pattern, the solution to be immersed in the third film is TMAH as compared with the conventional RELACS, so that a finer resist pattern can be formed using existing equipment. It is possible to form. Therefore, a high-performance semiconductor device can be realized at lower cost.

According to the second method for forming a resist pattern, since the same material is used for the second film and the third film, the same equipment can be used, so that a fine resist pattern can be formed at low cost.

According to the third method for forming a resist pattern, it is possible to form a fine resist pattern, and there is no step for forming a third film as compared with the first embodiment. Ability can be realized.

[Brief description of the drawings]

FIG. 1 is a process sectional view showing a resist pattern forming method according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing a step of the method for forming a resist pattern according to the first embodiment of the present invention;

FIG. 3 is a sectional view showing a step of the method for forming a resist pattern according to the first embodiment of the present invention;

FIG. 4 is a process cross-sectional view showing a resist pattern forming method according to the first embodiment of the present invention.

FIG. 5 is a process sectional view showing a resist pattern forming method according to a second embodiment of the present invention.

FIG. 6 is a process sectional view showing a resist pattern forming method according to a second embodiment of the present invention.

FIG. 7 is a process sectional view showing a method for forming a resist pattern according to a second embodiment of the present invention.

FIG. 8 is a process sectional view showing a method for forming a resist pattern according to a second embodiment of the present invention.

FIG. 9 is a view showing line width-focus dependency according to the second embodiment of the present invention;

FIG. 10 is a sectional view showing a step of the method for forming a resist pattern according to the third embodiment of the present invention.

FIG. 11 is a process sectional view showing a method for forming a resist pattern according to a third embodiment of the present invention.

FIG. 12 is a process sectional view showing a method for forming a resist pattern according to a third embodiment of the present invention.

FIG. 13 is a sectional view showing a step of the method for forming a resist pattern according to the third embodiment of the present invention.

FIG. 14 is a diagram showing a line width-focus dependency according to the third embodiment of the present invention;

[Explanation of symbols]

 101 semiconductor substrate 102 first film 103 hot plate 104 resist 105 hot plate 106 second film 107 hot plate 108 mask 109 hot plate 110 developer 111 first resist pattern 112 third film 113 hot plate 114 TMAH aqueous solution 115 Second resist pattern 201 Semiconductor substrate 202 First film 203 Hot plate 204 Resist 205 Hot plate 206 Second film 207 Hot plate 208 Mask 209 Hot plate 210 Developer 211 First resist pattern 212 Third film 213 Hot plate 214 TMAH developer 215 Second resist pattern 301 Semiconductor substrate 302 First film 303 Hot plate 304 Resist 305 Hot Rate 306 second layer 307 hot plate 308 mask 309 hot plate 310 developer 311 first resist pattern 312 hot plate 313 TMAH aqueous solution 314 second resist pattern

Continued on the front page F term (reference) 2H025 AA02 AB16 AC08 AD03 BE00 BE10 BG00 CB41 DA01 FA17 FA29 FA33 FA39 2H096 AA25 BA11 EA05 FA01 GA09 HA01 HA05 JA04 5F046 AA28

Claims (10)

[Claims] A step of forming a first resist pattern on a semiconductor substrate; a step of applying a first film on the first resist pattern; a step of forming the first resist pattern and the first film; And forming a second resist pattern by immersing the first resist pattern and the first film in an aqueous solution of tetramethylammonium hydroxide to form a second resist pattern. 2. The resist pattern forming method according to claim 1, wherein a material for forming the first resist pattern is a chemically amplified resist. 3. The resist pattern forming method according to claim 1, wherein the first film uses a material containing a water-soluble film forming component and a surfactant. 4. The resist pattern forming method according to claim 1, wherein the first film uses a material containing a water-soluble film forming component and a surfactant containing a sulfonate. Pattern formation method. 5. A step of applying a resist on a semiconductor substrate, a step of heat treating the resist, a step of applying a second film on the resist, a step of heat treating the second film, Performing a step of exposing the resist and the second film via a predetermined mask, a step of heat-treating the resist and the second film, and a developing treatment of the resist and the second film Forming a first resist pattern; applying a third film on the first resist pattern; heat treating the first resist pattern and the third film; Forming a second resist pattern by dipping the resist pattern in the third film and an aqueous solution of tetramethylammonium hydroxide to form a second resist pattern. 6. The method according to claim 5, wherein the second film and the third film use the same material. 7. The resist pattern forming method according to claim 5, wherein the resist is a chemically amplified resist. 8. The resist pattern forming method according to claim 5, wherein the heat treatment of the first resist pattern and the third film has a heat treatment temperature of 80 ° C. to 160 ° C. Pattern formation method. 9. A step of forming a first resist pattern on a semiconductor substrate, a step of heat-treating the first resist pattern, and a step of immersing the first resist pattern in an aqueous solution of tetramethylammonium hydroxide. 2
Forming a resist pattern. 10. The method for forming a resist pattern according to claim 1, wherein the aqueous solution of tetramethylammonium hydroxide is a 2.38% aqueous solution of tetramethylammonium hydroxide.