JPH0284656A - Pattern forming method - Google Patents

Abstract

PURPOSE:To form a fine resist pattern having a good shape by forming a resist, followed by treating the obtd. resist with an aqueous solution, and then exposing and developing the obtd. resist to form a resist pattern. CONSTITUTION:A positive resist 2 is formed on a semiconductor substrate 1, and the surface of the resist 2 is formed (patterned) in a state of meniscus. A layer 200 to be treated is formed on the surface of the resist 2 by processing the resist 2 as mentioned above, and the resist 2 is made hardly soluble in an alkali developer. Next, even if an UV light 5 is selectively exposed on the resist 2 through a mask 4, the unexposed part of the resist 21 does not dissolve at a following development step. Subsequently, the resist 2 is subjected to a paddle development with an alkali developer to remove the exposed part 20 of the resist, thereby forming a resist pattern 2A. Thus, a prescribed fine resist pattern having the good shape is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a pattern forming method in a phosphorography process for semiconductor manufacturing or the like.

BACKGROUND OF THE INVENTION In a phosphorography process in semiconductor manufacturing, it is most important to form a fine resist pattern with a good shape.

However, the currently used ultraviolet rays [g-rays (, *
senm) light, i-line (365 nm) light, etc.] and excimer laser light [MurF (193n!l) light, KrF (2
4 nm) light, XaCl (308 nm) light, etc.], fine (for example, 0.5 μm
To obtain a pattern with a good shape (around 1.0 μm) is...
This is often difficult due to its optical pattern resolution ability.

A pattern forming method for such a conventional technique will be shown using FIG.'s8. A positive resist (M
PS-1400 Nijiplay Co., Ltd.) 2 was formed to have a thickness of 1.2 μm. (Figure 8a) Next, g-line (4senm
) selectively exposing light 4 through a mask 6; The exposure device used at this time is a reduction projection exposure device (lens numerical aperture 0).
, 42: Nippon Kogakusha), and the exposure amount was 220 'II.
J/(d) (Figure 8b).Finally, paddle development was performed for 60 seconds using an alkaline developer (MF319; Sibley) to remove the exposed portion 2o of the resist and form a resist pattern 2B ( Figure 8C).

Problems to be Solved by the Invention However, although pattern 2B was a line and space Φ pattern of 0.6 μm, it was a defective pattern characterized by approximately 16 inches of pus loss and a poor semicircular shape. . This type of defective pattern is caused by the fact that the mask pattern has a pattern size near the limit of the optical system, so the light is diffracted to the part directly under the mask in the unexposed area, as shown in Figure 1, and the exposure is delayed. This is thought to be due to the fact that the area was developed and removed.

Such defective patterns can cause dimensional variations in subsequent processes such as etching and ion implantation.
This was a cause for concern because it caused a decrease in yield in semiconductor device manufacturing.

In addition, in an attempt to form patterns with good shape in phosphorography using electron beams or ultraviolet rays, after treating the electron beam resist or ultraviolet ray resist with an organic solvent (chlorobenzene), electron beam irradiation, ultraviolet ray exposure, and development are performed. methods have been proposed (for example, Mitani et al., Proceedings of the 1985 Spring Conference of the Japan Society of Applied Physics, P, 414.29
5L-N-4 (1987)).

However, with this method, there is a risk that chlorobenzene, which is an organic solvent, may mix with or react with the resist, causing deterioration of the sensitivity of the resist or deformation of the pattern during pattern formation, and it is difficult to control the processing time of chlorobenzene. If the processing time is too short, there will be no effect, and if the processing time is too long, the resist in the exposed area will become completely insolubilized and development will become impossible. Furthermore, it is difficult to control the processing temperature, and as a lithography process, the control unit is extremely difficult and cannot be used stably. or,
The basic problem is that because a growth solvent is used, its use is unfavorable from a safety and health standpoint, and there are also problems from an industrial physiological point of view.

In addition, contrast enhancement lithography (CICI) is one of the photolithography techniques.
ast ] Enhanoed Lithography
) is proposed. For example, B, F, Griff
ing (BF Griffey) at al
, IKKICE ElectronDevice Le
tter (Iiii Electron Device Letter 3, EDL-, P, 4 (1982), this is
This is a technique in which a well-shaped resist pattern with improved contrast can be obtained because the color fading layer formed on the resist transmits only light components with high intensity of incident light, that is, light components with improved contrast, into the resist.

However, even when such CKL technology is used, the improvement in the contrast of the incident light is not noticeable when the pattern is submicron or smaller, especially about 0.5 μm.
The pattern shape can no longer be said to be good.

With reference to FIG. 9, for conventional patterning methods, a water-soluble CIEL material (e.g., M, Sasag) is used.

et al, Proo, 5PIJ e31. P, 32
1 (1986)) is used.

A positive resist (MPS1400: Sibley Co., Ltd.) 2 is formed on the substrate 1 to a thickness of 1.2 μm.

(FIG. 9a) Next, a water-soluble CKL material 6 having the following composition is applied to a thickness of 0.16 μm.

(The following is a blank space) Note that the contrast effect coefficient m obtained by dividing the logarithm of the ratio of the transmittance before and after exposure at 4381 m of this material layer θ by the film thickness was 12. (FIG. 9b) Next, G-line (43sn heavy) light 4 is selectively exposed through a mask 6. Note that the exposure at this time was performed using a reduction projection exposure device (lens numerical aperture 0.4).
2: Nippon Kogakusha), and the exposure amount was 240 rtrJ/d.
Met.

(FIG. 9O) Finally, paddle development was performed for 60 seconds using an alkaline developer (MF319, manufactured by Sibley Co., Ltd.) to remove the aqueous 11c EL layer 6 and the exposed portion 2o of the resist 2, thereby forming a resist pattern 2B'. (Figure 9d) Obtained pattern 2B
' was a 0.6 μm line-and-space pattern, but due to the light diffraction phenomenon, the light went around to areas that should have been unexposed and was developed, resulting in a film loss of about 10 inches. It was a defective pattern with an aspect ratio of 66°. Such a defective pattern with a poor shape as shown in Figure 2(d) causes dimensional variations in subsequent processes such as etching and ion implantation, so there is concern that it may lead to a decrease in the yield rate of semiconductor device manufacturing. It was an issue that should be addressed.

In addition, cxM, which is a commercially available water-insoluble OIL material,
Similar results were obtained when 42o (Nagase Sangyo) (mu=12) was used.

An object of the present invention is to easily solve the problem of pattern shape deterioration in conventional pattern forming methods using an industrially advantageous method.

An object of the present invention is to form a fine resist pattern with a good shape by performing simple processing on the surface of the resist film after forming the resist 1111.

Another object of the present invention is to form a fine resist pattern with a good shape even in a method using a contrast-enhancing material.

Means for Solving the Problems The present invention is a pattern forming method characterized in that after forming a resist, the resist is treated with an aqueous solution, and then the resist is exposed and developed to form a resist pattern.

The pattern forming method of the present invention includes forming a resist on a substrate, subjecting the resist to an aqueous solution treatment to form a surface treatment layer that is difficult to develop, and then selectively exposing and developing the resist to remove the resist. In this method, a resist is selectively removed to form a pattern of the resist, and after forming a resist on a substrate, the resist is subjected to an aqueous solution treatment to form a treated layer that is difficult to develop, and then the resist is removed on the resist. A method of forming a photobleachable layer, selectively exposing the resist to light, removing the photobleaching layer, developing the resist and selectively removing the resist to form a pattern of the resist. be. Furthermore, the present invention forms a resist on a substrate, subjects the resist to an aqueous solution treatment to form a treated layer that is difficult to develop, and then selectively exposes the resist to light in an atmosphere free of moisture. A method in which the entire surface is exposed to light and the resist is selectively removed by development to form a resist pattern, or a resist is formed on the substrate and an aqueous solution treatment is performed to form a treated layer that is difficult to develop. After forming a photobleaching layer on the resist and selectively exposing the resist to light, the entire surface is exposed to light in an atmosphere free of moisture, and the resist is selectively removed by development. This is a pattern forming method for forming a pattern.

Function The present invention performs aqueous solution treatment after resist formation, and performs exposure and
This is a method of forming a pattern through development.

By this method, the difference in dissolution rate in the developing solution between the unexposed and exposed areas of the resist increases, and a well-shaped fine pattern with improved contrast can be obtained very easily.

This method is well compatible with methods for improving the contrast of the resist, such as using a photobleachable compound layer or deep ultraviolet irradiation, and exhibits greater effects. Further, a surfactant may be included in the aqueous solution, and heating may be applied after the aqueous solution treatment.

These materials and treatments further increase the difference in dissolution rate in the phenomenon liquid between the unexposed and exposed areas of the resist and improve the contrast.

As described above, according to the present invention, the difference in the dissolution rate in the developing solution between the unexposed area and the exposed area of the resist is increased, and a well-shaped resist pattern can be easily obtained.

EXAMPLE The present inventors have discovered that the aqueous solution treatment of the present invention makes it possible to form an excellent resist pattern in that the upper part of the resist is not easily soluble in an alkaline developer. This phenomenon led to an increase in the difference between the development speed of the exposed area and the development speed of the unexposed area during exposure and development. That is, due to the aqueous solution treatment according to the present invention, the development speed of the exposed area was almost unchanged compared to the case without such treatment. However, the unexposed areas that should originally be shielded from light by the mask,
Even if the resist is exposed to weak diffracted light that is incident on the unexposed areas of the resist, it becomes difficult to dissolve in the developer because the above-mentioned upper layer that is difficult to dissolve in the developer is formed. Therefore, there is no inconvenience that parts that should not be removed by development are removed by development, and the diffraction of light can be completely ignored, and the development speed of the parts that should not be removed is significantly reduced, and A well-shaped resist pattern was formed.

It was clear that such an increase in the difference in development speed between the exposed and unexposed areas resulted in an increase in the contrast of the resist pattern. The reason why the upper part of the resist becomes difficult to dissolve in an aqueous solution such as an alkaline developer is thought to be because the upper part of the resist becomes hydrophobic or non-photosensitive due to the aqueous solution. That is, for example,
In a normal positive resist consisting of a diazonaphthoquinone compound and a novolac resin, the molecular weight at the top of the resist increases due to aqueous treatment (bonding between the diazonaphthoquinone compound and novolac resin, bonding between novolak and cooking resin, etc.), It can be considered that OHg of the novolak resin is blocked by the diazonaphthoquinone compound, or that the N2 group, which is a photosensitive group of the diazonaphthoquinone compound, becomes -N=N- and bonds to the resin.

Here, due to the effect of increasing the molecular weight and crosslinking on the upper part of the resist by aqueous solution treatment, the difference in dissolution rate between exposed and unexposed areas is large even when developed with an organic solvent, and the pattern is Contrast is improved.

In addition, such surface treatment methods can be used in conjunction with methods to improve pattern contrast, such as the use of contrast-enhancing materials and full-surface exposure in an atmosphere free of water, to achieve good effects on pattern formation. becomes even larger.

Of course, exposure of the entire surface of the contrast-enhancing material in a moisture-free atmosphere may be used simultaneously with the surface treatment method, and the effect will be even greater. In addition, the aqueous solution used in the surface treatment method may contain a surfactant, which can further increase the effect of suppressing pattern deterioration due to light diffraction in unexposed areas of the resist, and produce good results. Further, heating after the aqueous solution treatment is also very effective in preventing pattern deterioration due to optical diffraction.

According to the method of the present invention, a resist pattern can be easily formed in a good shape and in accordance with dimensions with high accuracy in a lithography process, and is suitable for manufacturing ultra-fine semiconductor elements.

Specific examples will be described below.

(Part 1) As shown in FIG. 1, a normal positive resist (MPS-1400; Sibley Co., Ltd.) 2 made of a diazonaphthoquinone compound and a novolac resin is formed on a semiconductor substrate 1 to a thickness of 1.2 μm ( (See Figure 1). Next, MF-319 (manufactured by Sibley), which is an aqueous alkaline solution, was raised in a meniscus shape on the resist 2 by the paddle method and left stationary for 60 seconds. 3 indicates an alkaline aqueous solution (Fig. 1b).

Through this treatment, a layer 200 to be treated is formed on the surface of the resist 2, and this layer 200 exhibits the above-mentioned effect and becomes difficult to dissolve in an alkaline developer.

Next, mask 4 of ultraviolet light gi (43 enm + light 5).
selectively exposed through. The exposure device at this time was a reduction projection exposure device (lens numerical aperture 0.42; manufactured by Nippon Kogaku Co., Ltd.), and the exposure amount was 250 mJ/c4. At this time, as shown in FIG. 30, even if a part of the ultraviolet light 5 goes around from the edge of the mask and exposes the shielded part of the mask, a layer 20o to be processed that is difficult to dissolve in the alkaline developer is formed there. The resist 21 in the unexposed area is removed in the next development process.
does not dissolve. After this, the alkaline developer M
Perform paddle development for 60 seconds using F-319 and expose area 2.
0 was removed to form a resist pattern 2 (FIG. 1d). As shown in the figure, the two obtained patterns have a steep aspect ratio of s9' with no film loss at 0.611 m.
It was a line and space pattern.

In this example, the aqueous solution treatment was performed using the same developing solution for the resist, but of course other different alkaline aqueous solutions, alkaline developing solutions, and other aqueous solutions (acidic aqueous solution, neutral aqueous solution) may be used.

The processing temperature of the aqueous solution is arbitrary and there are no particular restrictions.
Temperature during pattern formation (e.g. around 15-26"C)
I went there and confirmed that there was no problem.

As is clear from this example, in the aqueous solution processing according to the invention, it is possible to use the developing solution used in the normal process as it is, and it is very difficult to process the process when using it for the heritage of semiconductor manufacturing. It is easy to understand and has high industrial value.

In this respect as well, it is very advantageous in terms of throughput and process simplification compared to conventional organic solvent treatment.

(Part 2) MP2400, a far ultraviolet resist, was used as a resist.
Sibley), aqueous solution treatment was performed by immersion in a 2.38% tetramethylammonium hydroxide aqueous solution for 20 seconds, and exposure using a KrFz ximer laser stepper with a lens numerical aperture of 0.35. 20% as EIJ/c11° development
60 with MP2401 alkaline developer (Sibley)
By performing the same process as in Example 1 under the second paddle condition, an aspect ratio of 89 with no film loss was obtained.
A line and space pattern with a steep angle of 0.36 μm was obtained.

As described above, when a good resist pattern with an intact shape that can be formed by the present invention is formed, this pattern can be etched with desired precision when etching the semiconductor substrate 1 or the object to be etched formed on the substrate 1. A detailed etching process can be performed. That is, by forming an accurate resist pattern using the present invention, highly accurate etching becomes possible, which is extremely convenient for manufacturing fine semiconductor devices.

Additionally, methods related to the present invention will be discussed.

Regarding aqueous solutions, alkaline aqueous solutions are most effective, but water and other solutions can also exhibit similar performance. In particular, examples of the alkaline aqueous solution include an aqueous tetramethyl hydroxide ammonium solution and a choline aqueous solution. The treatment with the aqueous solution can be carried out by dipping, paddling, spraying, or a combination of these methods, but is not limited to these methods, and any method may be used as long as it comes into contact with the upper part of the resist.

The resist according to the present invention is a positive type that can be developed with an alkali,
Alternatively, a negative resist is preferable, but can be used without any particular restriction. Regarding development, alkaline development is generally used, but this may vary depending on the resist used.

Exposure is often performed using ultraviolet light or excimer laser light, but may also be performed using electron beams or X-rays. In the case of using electron beams or X-rays, pattern deterioration due to electron scattering can be prevented by the upper layer of the resist, which is hardly soluble in the developing solution, and a good pattern can be obtained.

In addition, the pattern obtained by the present invention has improved heat resistance against the subsequent heat treatment process due to the action of the layer on the top of the resist that becomes difficult to melt due to aqueous solution treatment, and has improved heat resistance of 20°C compared to patterns obtained by conventional methods. Improved heat resistance (
A thermal softening point of approximately 140'C or higher) was observed.

Further, the aqueous solution treatment time is not particularly limited, and since the reaction occurs instantaneously, a treatment time of, for example, 10 minutes or less is often sufficient. Of course, even if the processing time is longer than this,
No development was observed in which the exposed areas of the resist became insolubilized and could no longer be dissolved in the developer. In other words, the effect that aqueous solution treatment makes it difficult for the upper part of the resist to dissolve in the developer is different from the resist insolubilization phenomenon caused by conventional organic solvent treatment.
It was found that the reactions were different. This is believed to be because, in the aqueous solution treatment of the present invention, even if the treatment time is short, the reaction between the upper part of the resist and the aqueous solution hardly progresses after a certain period of time. It is thought that in the conventional treatment using an organic solvent, the resist becomes insolubilized in the developing solution as the treatment time increases. Therefore, in the present invention, the processing time can also be set arbitrarily.

Note that the treatment temperature of the aqueous solution according to the present invention is arbitrary, and there was no difference in the effect of the invention depending on the temperature.

In addition, since the present invention uses an aqueous solution, there is no problem with the safety and hygiene of phosphorography, and since it is an aqueous solution, it is easy to handle, which facilitates the introduction of the present invention into a mass production process. , it becomes easier to manage the process, and it also leads to an improvement in the yield of device manufacturing.

Furthermore, since the present invention uses aqueous solution processing, no phenomenon was observed in which the performance of the resist changed due to mixing or reaction with the resist during the processing.

In addition to the resists described in the examples above, the present invention also provides positive resists (OFPR-800°, 0FPR-5000, etc.) using diazonaphthoquinone compounds.
, 0FPR-8900 (Tokyo Ohkasha), HPR-2
04, HPR-1182 (Fuji Hunt), Mu Z5
214 (Hoechst 3MP2400-17, dye-containing resist Mp14oo-D2 (Sibley), etc.) and negative resists using azide compounds (RU-
1100N, RD-200ON (Hitachi Chemical).

NNR747 (Nagase Corporation), etc.) and main chain cleavage type positive resist (PMCI (Sibley Corporation)).

PMIPM, PMM (Tokyo Ohkasha, etc.) and polymerized negative resists (0M8,5IR (Tosoh, P)
MG (Tokyo Ohka), etc.), etc.), the same good results as in this example can be obtained. of course,
It is not limited to these. It goes without saying that the present invention can also be applied to manufacturing other than semiconductor devices.

(Part 3) As shown in FIG. 2, a positive resist (MPS1400 manufactured by Niji Play Co., Ltd.) 2 is formed on a substrate 1 such as a semiconductor to have a thickness of 1.2 μm. (FIG. 2a) Next, an aqueous alkaline solution, MV-319 (manufactured by Prey Co., Ltd.), was heaped up in the shape of a meniscus on the resist 2 by the paddle method and left stationary for 60 seconds. 3 indicates an alkaline aqueous solution. (FIG. 2b) This treatment forms a treated layer 200 on the surface. Next, a layer 6 of a water-soluble CKL material, which is a photobleachable layer according to the present invention and has the following composition, is applied to a thickness of 0.16 μm.

The coefficient of contrast enhancement in 4361t11 of layer e of this water-soluble GEL material was 12.0. (FIG. 20) Thereafter, the resist 2 is selectively exposed to g-line (436 nm) light 4 through a mask 6. The exposure at this time was performed using a reduction projection exposure device (lens numerical aperture 0.42: Nippon Kogaku Co., Ltd.), and the exposure amount was 260 mJ/(-d). Paddle development was performed for 60 seconds using a developer (Sibley MF319) to remove the water-soluble CIEL layer 6 and further remove the hawk-lighted area 2o of the resist, forming two resist patterns υ such as the unexposed area 21. (Figure 2e) The obtained pattern 2 has an aspect ratio of 8 with no film loss as shown in the figure.
It was a 0.5 μm line and space pattern with a steep angle of 9 degrees.

In this example, the aqueous solution treatment was performed using the same developing solution for the resist, but of course other different alkaline aqueous solutions, alkaline developing solutions, and other aqueous solutions (acidic aqueous solution, neutral aqueous solution) may be used.

The processing temperature of the aqueous solution is arbitrary and there are no particular restrictions.
It was confirmed that there was no problem at all by performing the process at the temperature used for forming the pattern (for example, around 16 to 25 degrees).

As is clear from this example, in the aqueous solution processing according to the present invention, it is possible to use the developing solution used in the normal process as is, and it is very suitable for use in mass production of semiconductor manufacturing. The process is simple and has high industrial value.

In this respect, it is also much faster than conventional organic solvent treatment.
This is very advantageous in terms of output and process simplification.

(Part 4) Positive resist (MPSL 400
Nijiplay Co., Ltd.) 2 was formed to have a thickness of 1.2 μm. (Fig. 3 1L) Next, aqueous alkaline solution (2.38%
Tetramethylammonium hydroxide aqueous solution)
The above-mentioned substrate was immersed in a dipping method for 926 seconds to form a layer 200 to be treated.

(Fig. 3b) Next, layer 8 of Bees (Nagase Sangyo) is 0.12μ! After forming the layer 9 with a thickness of 11, a layer 9 of 08M420 (Nagase Sangyo) was formed with a thickness of 0.7 μm. CICM4
436 nl of 20! The mu value at l is 12.0.

(FIG. 30) After this, the resist 2 is selectively exposed to g#j (438 nll) light 4 through the mask 6.

The exposure at this time is performed using a reduction projection exposure device (lens numerical aperture 0,
42: Nippon Kogakusha), and the exposure amount was 400 rn.
J/(-d. (Fig. 3) The layer 9 of CICM420 was removed using a paddle for 60 seconds, dosm 15 (Nagase Sangyo), and the layer 9 of the CICM420 was removed using a paddle for !7eO seconds using an alkaline developer (MF3f9, manufactured by Sibley Co., Ltd.). Development was performed to remove the Be5O layer 8 and the exposed portion 20 of the resist to form two resist patterns.(Fig. 5e) The obtained pattern 2C has an aspect ratio with no film loss. It was a steep 0.5μtrr line and space pattern of 89°.

(Part 5) Far ultraviolet positive resist (MP24
00 Nijiplay Co., Ltd.) 10 is formed to have a thickness of 1.2 μm. (Figure 4a) Next K, MP which is an alkaline aqueous solution
An aqueous solution 11 prepared by diluting 2401 (Sibley) with water at a ratio of 1=10 was sprayed onto the resist 10 for 6 seconds to form a treated layer 200. (Fig. 4b) Next, as an intermediate layer, a layer 12 of a 10% aqueous solution of pullulan (Hayashibara Biochemical Research Institute: molecular weight 39,000) is formed to a thickness of 0.15 μm, and has the following composition. A photobleaching layer 13 according to the present invention was applied to a thickness of 0.25 μm.

(The following is a blank space) The contrast enhancement coefficient of this photobleaching layer 13 at 248.4 nm was 10.0. Here, the intermediate layer 12 mainly functions to prevent mixing of the resist 10 and the photobleachable layer 13. (Figure 4C
) Thereafter, the resist 10 is selectively exposed to KrFz ximer laser (248.4 nm) light 14 through the mask 4. Note that the exposure at this time was performed using a KrF reduction projection exposure device (
The lens numerical aperture is 0.36), and the exposure amount is 280 m.
It was J/d. (Fig. 3d) Finally, puddle development is performed for 60 seconds using an alkaline developer (20cm MP2401) to remove the intermediate layer 12 and the photobleaching layer 13, and furthermore, the exposed area 10m of the resist 10 is removed. It was removed to form a resist pattern of 10m. (Figure 4e) The obtained pattern 10mm has an aspect ratio of 88 without film loss.
It was a 0.3 μm line and space pattern.

(Part 6) MP2400 (1.2 μm thick) as a resist, immersed in a 2% choline aqueous solution for 15 seconds as an aqueous solution treatment, and a layer with the following composition as a photobleaching layer (0.2 μm thick 24B, 4 nm)
11.0), and the lens numerical aperture was 0.0.
390 m with 36 KrF excimer laser stems
J/d, the same experiment as in Example 3 was conducted under the conditions of 60 seconds puddle using 20% MP2401 alkaline aqueous solution as development, and a 0.375 μm line and space pattern with an aspect ratio of 89° and no film loss was obtained. T-4ri.

As described above, by forming a good resist pattern with no shape distortion and improved contrast using the method of the present invention, the substrate 1 or the object to be etched formed on the substrate 1 can be etched using this resist pattern as a mask. It becomes possible to carry out desired and accurate etching. Therefore, it greatly contributes to high-precision microfabrication in the manufacture of semiconductor devices and the like.

Regarding aqueous solutions, alkaline aqueous solutions are most effective, but water and other solutions can also exhibit similar performance. In particular, examples of the alkaline water injection solution include a tetramethylammonium hydroxide aqueous solution and a choline aqueous solution.

The aqueous solution treatment can be carried out by dipping, puddling, spraying, or a combination of these methods, but is not limited to these methods, and any method that comes into contact with the resist surface may be used.

The resist according to the present invention is preferably a positive type or negative type resist that can be developed with an alkali, but it can be used without particular limitations. Regarding development, alkaline development is performed within the film, but this may vary depending on the resist used.

Furthermore, the pattern obtained by the present invention has improved heat resistance against the subsequent heat treatment process due to the action of a layer that makes the resist surface less soluble due to aqueous solution treatment, and can be heated up to 20°C compared to patterns obtained by conventional methods. It was observed that the heat resistance was improved (thermal softening point was about 140°C or higher).

Furthermore, there is no particular limitation on the aqueous solution treatment time according to the present invention since the reaction occurs instantaneously. For example, a processing time of 10 minutes or less is often sufficient. Of course, even if the processing time was longer than this, no phenomenon was observed in which the exposed areas of the resist became insolubilized and could not be dissolved in the developer at all. In other words, it has been found that the action of making the resist surface less soluble in the developing solution due to the aqueous solution is different from the conventional insolubilization phenomenon of the resist surface due to treatment with an organic solvent, for example.

(In conventional processing using organic solvents, it is thought that as the processing time increases, the insoluble layer to the developing solution increases.) In the aqueous solution processing of the present invention, even if the processing time is extended, only the extremely thin portion of the surface is removed. It only becomes more difficult to dissolve, and it is thought that the insolubilization of the inside of the resist in the developing solution is progressing due to the increase in processing time.

Note that the treatment temperature of the aqueous solution according to the present invention is arbitrary, and there was no difference in the effects of the invention depending on the temperature.

In addition, since the present invention uses an aqueous solution, there is no problem in terms of safety and hygiene in phosphorography, and since it is an aqueous solution, it is easy to handle, and this leads to simplification when introducing the present invention into a process. Process control becomes easier, which leads to improved yields in device manufacturing, and is also advantageous in terms of mass production.

Furthermore, since the present invention uses aqueous solution processing, no phenomenon was observed in which the performance of the resist changed due to mixing or reaction with the resist during the processing.

Note that the photofading layer according to the present invention may be any layer as long as it has an A value of 100% (for example, 4 or more) with respect to exposure light. For example, the photobleaching layer may contain a diazo compound, a nitrone compound, a styrylpyridine compound, or a mixture thereof. Those suitable for C-line (436 nm) light include 4,4'-dimethylaminobenzenediazonium salt; those suitable for one-line (36 nm) light include 4-morpholinobenzenediazonium salt;
Examples of compounds suitable for KrF excimer laser (24B, 4 nm l light include 6-diazomeldrum acid, but these are just examples, and the present invention is not limited thereto. In addition to the resists described in the Examples shown above, the present invention also provides a positive resist (OFPR-goo) using a diazonaphthoquinone compound, for example.

0FPR-5000, 0FPR-8900 (Tokyo Ohkasha), HP R-204, HP R-1182 (Fuji Hunt), Person Z5214 (Hoechst) MP24
00-17, MPl 400, a dye-containing resist
RU-110ON, RD-200
ON (Hitachi Chemical Co., Ltd.), NNR747 (Nagase Co., Ltd., etc.) or main chain cleavage type positive resist (PMGI (Sibley Co., Ltd.) etc.), etc.), the same good results as in the examples of the present invention were obtained. is obtained. Of course, it is not limited to these. It goes without saying that the present invention can also be applied to manufacturing other than semiconductor devices.

As in the present invention, it is clear that an increase in the difference in development speed between exposed and unexposed areas results in an increase in the contrast of the resist pattern itself, and this contrast improvement effect from the resist side is the fading layer)
It was found that, in combination with the effect of improving the contrast of incident light, a fine, well-shaped, high-contrast resist pattern could be obtained. Of course, it is common knowledge in the prior art that the shape of the pattern cannot be improved by using CKL alone.

(Part 7) The steps of an embodiment of the pattern forming method of the present invention will be explained using FIG. A positive resist (
MPS-1400 (Sibley) 2 was formed to a thickness of 1.2 μm (Figure S a). Next, the alkaline normality is 0.24N.
An aqueous solution 16 of tetramethylammonium hydroxide was stirred with a paddle for 60 seconds to form a treated layer 200 (FIG. 5b). Next, G-line (AAENM) light 4 is exposed through a mask 6. The exposure device at this time was a reduction projection exposure device (lens numerical aperture 0.42: Nippon Kogaku Co., Ltd.), and the exposure amount was 300 mJ//11-4 (FIG. 5C). Next, far ultraviolet light (10mW/c4 at 264nI!l) emitted from the Xe lamp.
for 5 seconds under deep ultraviolet 1 in a nitrogen atmosphere without moisture.
6 (Fig. 5d). Finally, add alkaline developer (M
Paddle development was performed for 60 seconds using F-319 (Sibley, Inc.) to remove the exposed portion 2o of the g-line light 5 and form a pattern 2m of the resist 2 (fifth drawing). The obtained pattern 2 has a good aspect ratio of 89° with no film loss.
．． It was a 67zm line and space pattern. Such a good pattern without film fading is thought to be due to the fact that both the aqueous solution treatment and full-surface exposure, as described above, made the vicinity of the resist surface layer insoluble and prevented pattern deterioration due to diffracted light.

In this way, in the pattern forming method of the present invention, both the aqueous solution treatment and the full exposure in an atmosphere without moisture reduce the alkali dissolution rate near the resist surface and make it insolubilized, and the synergistic effect of these two factors is Yoshi,
Film thinning during development due to light diffracted and incident on unexposed areas is significantly reduced by its insolubilizing effect.

The mechanism of these insolubilization effects in the exposed area is as follows.
Possible causes include an increase in molecular weight due to polymerization of the resins in the resist or polymerization of the resin and the photoreceptor, or a decrease in the number of OH groups in the resin.

The aqueous solution generally includes an alkaline aqueous solution (tetramethylammonium hydroxide, choline aqueous solution, etc.), but is not limited thereto. Examples of the aqueous solution treatment method include immersion, paddle, spray, and a mixture of these.

The entire surface exposure may be carried out using either ultraviolet rays or deep ultraviolet rays, but it is preferably carried out in a vacuum or in a nitrogen atmosphere in order to prevent the photoreceptor in the resist from producing dicarboxylic acid due to the light and dissolving in the alkaline developer.

(Part 8) The steps of an embodiment of the pattern forming method of the present invention will be explained using FIG. A positive resist (
MPS-1400; Sibley) 2 is formed to a thickness of 1.2 μm (Fig. 5 (→). Next, the alkaline normality is 0.2
4N tetramethylammonium hydroxide aqueous solution 1
6 was poured using a paddle for 60 seconds to form a layer to be treated 200 (FIG. 5(b)). Next, a photobleachable material consisting of a ratio of 4-dimethylaminonaphthalenediazonium zinc chloride salt:boristyrene ρ-phonic acid:water=1:15 was applied to obtain a 0.15 μm photobleaching layer 17 (fifth Next, G-line light 6 was exposed through a mask 4.The exposure device at this time was a reduction projection exposure device (lens numerical aperture 0, 42
: Nippon Kogakusha) and the exposure amount is 330 mJ/c4
(Figure 5(d)), then the far ultraviolet 1es (10mW/at 2s4nm) emitted by the Xs clamp.
7) was irradiated for 5 seconds in a nitrogen atmosphere without moisture (FIG. 5(0)). Finally, use alkaline developer (MF-31
9; Sibley Co., Ltd.) for 60 seconds to remove the photobleaching layer 17 and the resist 2o in the exposed area of the light 6 to obtain a resist pattern 2m (FIG. 5(f')). The obtained pattern 2 has an aspect ratio of 8 with no film reduction.
It was a good 0.6μ theoretical line and space pattern of 9°.

In this step, similar good results were obtained when the photobleaching layer was removed (washed with water) before the entire surface was exposed.

As mentioned above, a good pattern like the one in this example is
This is due to both the above-mentioned effects of the surface insoluble layer and the light with improved contrast, and it is thought that the effects of improving both the resist side and the incident light side are synergistic.

As described above, in the pattern forming method of the present invention, both aqueous solution treatment and full-surface exposure in an atmosphere free of moisture reduce the rate of alkali dissolution near the surface of the resist exposed area and make it insolubilized. The fading layer reduces the incidence of diffracted light with low light intensity into unexposed areas. According to the interaction of these three types, less light is diffracted and enters the unexposed area, and
Due to the effects of the first two types of incident light, the exposed areas are made insolubilized during development, so there is no chance of film thinning.

The mechanisms of the former two types of insolubilizing the exposed area include an increase in the molecular weight due to polymerization of the resins in the resist or polymerization of the resin and the photoreceptor, or a decrease in the number of OH groups in the resin.

The absorption of low-intensity light by the photobleaching layer is performed by layers containing diazo compounds, nitrone compounds, styrylpyridine compounds, etc., and only high-intensity light bleaches these layers and impinges on the resist. In other words, light with improved contrast and less diffraction is incident.

The aqueous solution generally includes an alkaline aqueous solution (tetramethylammonium hydroxide, choline aqueous solution, etc.), but is not limited thereto.

Examples of aqueous treatment include dipping, puddling, spraying, or a mixture thereof.

The entire surface exposure may be carried out using either ultraviolet rays or deep ultraviolet rays, but it is preferably carried out in a vacuum or in a nitrogen atmosphere in order to prevent the photoreceptor in the resist from producing carboxylic acid due to the light and dissolving in the alkaline developer.

(Part 9) Positive resist (MPSL 400
; Sibley Co., Ltd.) 2 to a thickness of 1.2 μm. Next 5
CF3(CF2)7SO2N(0
A 0.24 N aqueous solution of tetramethylammonium hydroxide containing a surfactant of 2H5)(CH2CH20)14H was added for 60 seconds using a paddle. Next, G-line (43 enm) light is exposed through a mask. The exposure device used at this time was a reduction projection exposure device (lens numerical aperture 0.42: Nippon Kogaku Co., Ltd.), and the exposure amount was 260.
mJ/cd. Finally, add an alkaline developer (M
Paddle development was performed for 60 seconds using F-319 (Sibley, Inc.) to remove the exposed portion of the resist and form a resist pattern. The pattern obtained was a good line-and-space pattern with an aspect ratio of 89° with no film loss. This good pattern with no film sagging is due to the insolubilized layer blocking the diffracted light on the surface, and the film sagging and deformation caused by light diffraction of the putter, which occurred with conventional methods, is significantly reduced. It means that it was done.

As described above, in the pattern forming method of the present invention, the aqueous solution containing a surfactant reduces the dissolution rate of alkali near the surface of the exposed area of the resist and makes it insolubilized. The film loss during development due to the light is significantly reduced due to its insolubilizing effect.

Possible mechanisms for such an insolubilizing effect include an increase in the molecular weight due to polymerization of the resins in the resist or polymerization of the resin and the photoreceptor, or a decrease in the number of OH groups in the resin. For example, although such reactions generally occur in alkaline aqueous solutions, adding a surfactant can speed up the reaction.
It has been found that the pattern forming method of the present invention is extremely advantageous in terms of industrial throughput and yield.

Surfactants include those containing fluorine, ether bonds,
Those having a C0OH group, So, or H group are common, but are of course not limited to these. Examples of surfactants include CFs(CF2)7(CH2C
H20h. H, CFs((iF2)7SO2N(C2H
5) (α2■ρh4H.

CF5(CF2)7(CH2)sCON(CH3)(C
H2CH20)+oJC,F,5COONH4,C,F
, 5COOH, C8F, 7505H.

C, F, 5COON (CH3) 4.

OH3 (CJ)2CHCH2-C-CCH.

H CH3-CH2-C(CH5)-Cmi0-C(OH5)
Examples include -CH2-CH301(OH).

Examples of aqueous solutions according to the present invention include, but are not limited to, aqueous solutions of tetramethylammonium hydroxide, choline, and the like as alkaline aqueous solutions.

Examples of aqueous treatment include dipping, puddling, spraying, or a mixture thereof.

(Part 10) The pattern forming method of the present invention will be explained using FIG. 9.

TSMR8, which is a photosensitive resin 18, is placed on a substrate 1 such as a semiconductor.
900 to a thickness of 1.2 μm (Fig. 7(a)), tetraethylammonium hydroxide (0.24N)
15 for 60 seconds to form a layer to be treated 200 (FIG. 7(b)), followed by heating 19 at 100° C. for 90 seconds (FIG. 7(C)). A desired pattern exposure 6 is performed through a mask 4 using a g-line beam 5 (NAO, 42) (
FIG. 7(d)), development was performed for 60 seconds using NMD-3 to remove the exposed area 180, and a pattern of 18 mm was formed (
Figure 7(e)). The resulting resist pattern of 18 mm is a 0.5 μm line with an aspect ratio of 88° and no edges.
It was an and space pattern.

In this example, similar good results can be obtained even if the photosensitive resin is not heated after coating on the substrate when forming the photosensitive resin.

Thus, in order to overcome the problems of the prior art, the present invention provides a pattern forming method characterized by forming a pattern after performing aqueous solution treatment and heating.

According to the pattern forming method of the present invention, the alkali development insolubilization effect of the photosensitive resin by aqueous solution treatment is further enhanced by heating. Due to this effect, the photosensitive resin in the unexposed area becomes more difficult to dissolve in alkaline developer, which prevents the contrast of the pattern from decreasing due to diffracted light.
The pattern shape will be improved. On the other hand, the photosensitive resin in the exposed area becomes more soluble in alkali due to the photodecomposition of the photoreceptor (for example, the formation of indene carboxylic acid), so its dissolution rate in the developer remains unchanged.

As described above, according to the method of the present invention, a pattern with a high aspect ratio can be formed without increasing the dissolution rate difference between the exposed and unexposed areas.

According to the present invention, it is considered that the insolubilization of the photosensitive resin by the aqueous solution treatment penetrated and diffused into the interior of the photosensitive resin due to heat.

The aqueous solution according to the present invention may be any one, such as tetramethylammonium hydroxide.

Examples include aqueous solutions of organic amines such as tetraethylammonium hydroxide, aqueous choline solutions, aqueous alkaline solutions such as jetanolamine, and other neutral and acidic aqueous solutions. The alkaline aqueous solution may contain additives such as surfactants.

Regarding heating, it is desirable that the temperature be about 130° C. or lower so as not to significantly reduce the sensitivity of the photosensitive resin.

Of course, the temperature is not limited to this range.

Heating may be carried out at any time after the aqueous solution treatment; it may be carried out before or after the treatment without light, or both before and after, and the effect of the heating will be fully exhibited.

It should be noted that such heating can of course be used in combination with the photobleachable compound layer and far ultraviolet irradiation in addition to the aqueous solution treatment, and the effect of improving the pattern shape of the - layer can be obtained.

Effects of the Invention As described above, according to the present invention, the unexposed portion of the resist,
The difference in dissolution rate in the developing solution in the exposed area is increased, and a desired fine resist pattern with a good shape can be formed, which greatly contributes to the production of high-density semiconductor integrated circuits and the like.

[Brief explanation of drawings]

FIGS. 1 to 7 are cross-sectional views of a pattern forming process according to an embodiment of the present invention, and FIGS. 8 and 9 are cross-sectional views of a conventional pattern forming process. 1...M board, 2...Positive resist, 2
o...Exposure section, 4...Mask, 6...
...Ultraviolet light, 200...Layer to be treated, 2 people...
...Resist pattern. Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures OA , 4-Pekun diagram diagram diagram diagram

Claims (15)

[Claims] (1) After forming a resist on a substrate and subjecting the resist to an aqueous solution treatment to form a surface treatment layer that is difficult to develop, the resist is selectively exposed and developed to selectively remove the resist. , a pattern forming method characterized by forming a pattern of the resist. (2) After forming a resist on the substrate, the resist is subjected to aqueous solution treatment to form a treated layer that is difficult to develop, and then
forming a photobleachable layer on the resist, selectively exposing the resist to light, removing the photobleaching layer, developing the resist and selectively removing the resist to form a pattern of the resist; A pattern forming method characterized by forming a pattern. (3) After forming a resist on the substrate and subjecting the resist to an aqueous solution treatment to form a treated layer that is difficult to develop,
A pattern forming method comprising selectively exposing the resist to light, exposing the entire surface of the resist to light in an atmosphere free of moisture, and selectively removing the resist by development to form a pattern of the resist. (4) After forming a resist on the substrate and performing an aqueous solution treatment to form a treated layer that is difficult to develop, forming a photobleachable layer on the resist, and selectively exposing the resist to water. The entire surface is exposed to light in an atmosphere free of
A pattern forming method comprising selectively removing the resist through development to form the resist pattern. (5) The pattern forming method according to any one of claims 1 to 3, wherein the aqueous solution is water or an alkaline aqueous solution. (6) The pattern forming method according to claim 5, wherein the alkaline aqueous solution is a tetramethylammonium hydroxide aqueous solution or a choline aqueous solution. (7) The pattern forming method according to any one of claims 1 to 4, wherein the aqueous solution treatment is performed by dipping, paddling, spraying, or a combination thereof. (8) The pattern forming method according to claim 2 or 4, wherein the photobleaching layer contains a diazo compound, a nitrone compound, or a styrylpyridine compound. (9) The pattern forming method according to claim 3 or 4, wherein the moisture-free atmosphere is a vacuum or a nitrogen atmosphere. (10) The pattern forming method according to claim 3 or 4, wherein the entire surface is exposed to ultraviolet light or deep ultraviolet light. (11) The pattern forming method according to any one of claims 1 to 4, wherein the aqueous solution contains a surfactant. (12) The surfactant is fluorine or ether bond or -C
12. The pattern forming method according to claim 11, which has an OOH group, a -SO_3H group, or a mixture thereof. (13) The pattern forming method according to any one of claims 1 to 4, characterized in that heating is performed after treatment with an aqueous solution. (14) The pattern forming method according to claim 13, wherein heating is performed before exposure. (15) The pattern forming method according to claim 13, wherein heating is performed after exposure.