JPS63158543A - Pattern forming process - Google Patents

Abstract

PURPOSE:To form a superfine relief pattern having high aspect ratio even at relatively low degree of exposure by exposing a pattern on a resist dry plate, forming a relief pattern and a continuous thin layer supporting the relief pattern by developing with aq. alkaline developing soln., then exposing the whole pattern to light. CONSTITUTION:A photo-set part 3 is formed by exposing a resist dry plate having a relatively thick photoresist layer 2 on a base 1, then unexposed photoresist layer is dissolved by developing the dry plate with aq. alkaline developing soln. Thus, the relief pattern 4 and a continuous thin layer 5 formed to one body with the relief pattern 4 and supported the relief pattern 4 are formed. Then, the relief pattern 4 and the continuous thin layer 5 supported the relief pattern 4 are crosslinked firmly to each other by exposing the whole pattern. The depth of the relief pattern 4 formed by this method is great, so a relief pattern having high aspect ratio is provided.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention is applicable to hologram image forming materials and LSI
This invention relates to a method for forming ultra-fine relief patterns of negative photoresists that can be used for microfabrication such as manufacturing.

[Conventional technology]

To form a relief pattern using a negative photoresist, first, an image area that is crosslinked and hardened by exposure and a non-image area that is unexposed are formed, and then the uncrosslinked non-image area is dissolved in a development process. This is done by removing. In order to obtain a relief image with good reproducibility through this development operation, it is necessary to irradiate the exposed area, which is to become the image area, with sufficient light; if the irradiation is insufficient, crosslinking will occur along with the unexposed area during development. A sufficient image area is also removed, making it impossible to obtain a desired relief image.

Therefore, when forming a relief pattern using a negative photoresist, in the area that should become the image area,
A sufficient amount of light is being irradiated.

However, depending on the application, it may not be possible to provide a sufficient amount of exposure. For example, when used for pattern formation of a VLSI or as an image forming material for a hologram, the relief image becomes ultra-fine, resulting in accuracy problems such as line thickening due to overexposure. In particular, when used as a hologram image forming material, there is a limit to the amount of exposure because it is a one-shot exposure, unlike a normal negative film that irradiates light separately into unexposed areas and exposed areas. Ultra-fine relief patterns formed with an exposure amount within such limits will relatively easily fall off during development.

These shortcomings are that Appl.

0ptles, 13, 129 (1974), and is the reason why the range of application of negative photoresists is limited.

The aspect ratio, expressed as the depth of the relief pattern to the line width of the relief pattern, is an important factor in the manufacture of LSIs, and in particular, in the field of relief holograms, it is the dominant factor that determines the diffraction efficiency. ing. If ultra-fine reliefs and turns fall off during development, a high aspect ratio cannot be obtained.

[Problems to be solved by the present invention]

In view of the problems of the prior art as described above, the purpose of the present invention is to
The object of the present invention is to provide a method capable of forming ultra-fine relief patterns with a high aspect ratio even with a relatively low exposure dose.

[Means for solving problems]

In order to achieve the above object, as a result of various studies, the first method was:
(2) a second step of developing the photoresist layer with an aqueous alkaline developer to form a relief pattern and a continuous thin layer that integrates with and supports the relief pattern; (3) A method for forming an ultra-fine relief pattern comprising a third step of exposing the entire surface of the developed photoresist layer to light, which increases the depth of the ultra-fine relief pattern more than the conventional method without reducing resolution. The inventors have discovered that it is possible to take the same measures, and have completed the present invention.

It has been found that even better effects can be obtained by employing the second, third, and fourth methods described below.

Second method: (1) a first step of exposing a pattern to a resist dry plate formed by forming a negative photoresist layer on a substrate that can be developed with an aqueous alkaline developer; and (2) forming the photoresist layer with an organic solvent. (3) a third step of developing the photoresist layer with an aqueous alkaline developer to form a relief pattern and a continuous thin layer that is integrated with and supports the relief pattern; (4) A method for forming ultra-fine turns, which comprises a fourth step of exposing the entire surface of the developed photoresist layer to light.

Third method: (1) a first step of exposing a pattern to a Lennost dry plate formed by forming a negative photoresist layer on a substrate that can be developed with an aqueous alkaline developer; (2) water! a second step of developing the photoresist layer with an alkaline developer to form a relief pattern and a continuous thin layer that is integrated with and supports the relief pattern; (3) the photoresist after the development; A method for forming an ultra-fine relief pattern, comprising: a third step of exposing the entire surface of the photoresist layer to light; and (4) a fourth step of immersing the photoresist layer after the entire surface exposure in dioxane.

Fourth method: (1) a first step of exposing a pattern to a resist dry plate formed by forming a negative photoresist layer on a substrate that is developable with an aqueous alkaline developer; and (2) exposing the photoresist layer with an organic solvent. (3) a third step of developing the photoresist layer with an aqueous alkaline developer to form a continuous thin layer that is integrated with the relief pattern and supports the relief pattern; (4) a fourth step of exposing the entire surface of the photoresist layer after the development; and (5) a fifth step of immersing the photoresist layer after the entire surface exposure in dioxane. ! How to form a turn.

The aqueous alkaline developer used in the present invention is preferably one that dissolves the unexposed negative photoresist and does not have a dissolving effect on a portion of the polymer crosslinked by exposure. Examples of alkalinizing agents having such effects include sodium silicate, potassium silicate, sodium metasilicate, sodium carbonate, potassium carbonate, sodium bicarbonate, tribasic sodium phosphate, tribasic potassium phosphate, and tribasic ammonium phosphate. , dibasic sodium phosphate, sodium borate, ammonium borate, sodium hydroxide,
These include inorganic alkalis such as potassium hydroxide, lithium hydroxide, and ammonia, and organic amines such as monoethanolamine, jetanolamine, triethanolamine, 2-cy:r-aminoethanol, and ethylenenoamine. They can be used alone or as a mixture of two or more. A suitable amount of a surfactant and other water-soluble organic solvents may also be added to this aqueous alkaline developer for the purpose of promoting dissolution or swelling of the photoresist layer. As the surfactant, anionic surfactants, nonionic surfactants, amphoteric surfactants, etc. can be used, and the water-soluble organic solvent preferably has a solubility in water of 3 qIb or more. Furthermore, additives such as antifoaming agents and wetting agents may be included as necessary.

In the immersion treatment using the organic solvent of the present invention, it is not necessarily necessary to form a relief pattern that is visible to the naked eye, and almost no surface irregularities are observed even when the resist coating surface is actually measured after the development treatment.

However, this immersion treatment operation shows a remarkable effect in leaving a relief pattern formed in a low exposure dose range that would easily detach from the substrate using conventional methods;
Furthermore, the effect is tremendous, such as making it possible to increase the depth of the relief pattern. Although the reason for this effect is not clear, by dipping treatment using an organic solvent, relatively low molecular weight uncrosslinked components remaining between the polymers crosslinked by light irradiation are extracted from between the crosslinked polymers. This is considered to be effective in improving the developer resistance of the crosslinked polymer portion and the developability of the unexposed area when developing with an aqueous alkaline developer.

The solvent used in the immersion treatment of the present invention is preferably a solvent that is a poor solvent for the negative photoresist, and a mixed solvent of a poor solvent and a good solvent may also be used. Further, the mixing ratio can also be changed in consideration of the development time. At that time, in order to minimize the influence of residual solvent in the photoresist layer, the boiling point of the solvent should be 135.
It is preferable that the temperature is below ℃. As a preferred solvent,
Examples include, but are not limited to, methyl isobutyl ketone, isozorobyl alcohol, a mixture of methyl isobutyl ketone and isozorobyl alcohol, and a mixture of dioxane and isozorobyl alcohol.

To illustrate the method of the present invention with figures, FIG. 1 shows a cross-sectional view of a Lennost dry plate with a thick photoresist layer 2 provided on a substrate 1. As shown in FIG. FIG. 2 shows a state in which a photocured portion 3 is formed by exposure. The photocured portion did not reach the substrate due to the amount of exposure. FIG. 3 shows that by developing with an aqueous alkaline developer, the unexposed portions of the photoresist layer are eluted, and a continuous thin layer 5 is formed which integrates with the relief pattern 4 and the relief/4' turns and supports the relief/9 turns. Indicates the state in which it is formed. Figure 4 shows that after development with an aqueous alkaline developer,
By exposing the entire surface to light, both the relief pattern and the continuous thin layer supporting the relief pattern are strongly crosslinked.

The depth of the relief pattern formed in this way is
It is larger than that obtained by normal development methods,
To provide a relief pattern with a high aspect ratio.

Hereinafter, the present invention will be specifically explained using examples.

[Manufacture of photosensitive resin]

p-7 enile/diethyl noacrylate 54.8F (
0.2 mol) and bisphenol A (1 mol) with ethylene oxide (6.2 mol) adduct 133.2# (0.2 mol)
66 mol) of the catalyst (6oon of diptyltin oxide)
, a stirring device with an inhibitor (phenothiazine 5 oap),
The mixture was charged into a reactor equipped with a nitrogen gas inlet tube, a thermometer, and a distillation tube, and the reaction was started by heating to 190° C. with stirring under a nitrogen gas atmosphere. Heating and stirring were then continued for 3 and a half hours to completely distill off the ethanol produced by the reaction, yielding a linear polyester resin with a hydroxyl value of 46.5.

The above linear polyester resin 100II was heated to 140°C and stirred, 9.0.9% of pyromellitic dianhydride was added, and stirring was continued for 20 minutes at normal pressure in a nitrogen atmosphere, and the acid value was 43. A side chain carmexyl group-containing photosensitive polyester resin of No. 5 was obtained.

Example 1 The above photosensitive resin was dissolved in cyclohexane to prepare a photosensitive resin solution with a non-volatile content of 7-.
(200 rpm/1 minute) This solution was applied onto a glass plate and heat treated at 100°C for 10 minutes to obtain a Lenost dry plate with a photoresist layer thickness of 0.95 μm.

The microrin pattern is brought into close contact with this resist dry plate,
Exposure was carried out under vacuum contact. At that time, a metal halide lamp was used as the light source. The light from this lamp was filtered to produce light with a wavelength of 490 nm, which was irradiated onto the dry plate. The irradiation dose was 100 units. After irradiation, this dry plate was developed by immersing it in a 20° C. aqueous alkaline developer having the following composition for 30 seconds. After development, the photoresist layer in the unexposed areas still remained on the glass plate when it was washed with water and dried.

Next, the entire surface of this dry plate was irradiated with 15 units of metal halide lamp with the filter removed. When the depth of the relief pattern was measured with a stylus meter, the line width was 1 μm.
m relief mother turn 0.95μm, line width 0.5μm
A value of 0.35 μm was obtained for the relief foot turn.

Note 1) Sodium tert-butylnaphthalene sulfonate based anionic world surfactant manufactured by Kako Atlas Co., Ltd. Example 2 The photosensitive resin solution prepared in Example 1 was applied onto a polyester film, and the A resist dry plate with a photoresist layer having a thickness of 2.5 μm was obtained by heat treatment in the same manner.

A 1982 Ugra test chart was brought into close contact with this Lennost dry plate, and exposed in the same manner as in Example 1 under vacuum contact. At that time, the irradiation dose was set to 5 units. After irradiation, this dry plate was developed by immersing it in a 20° C. aqueous alkaline developer having the same composition as in Example 1 for 30 seconds. After development, washing with water and drying revealed that the photoresist layer in the unexposed areas remained on the polyester film with a thickness of 1.4 μm.

Next, the entire surface of this dry plate was irradiated with 15 units in the same manner as in Example 1. When the depth of the relief pattern was measured using a stylus meter, a value of 1.1 μm was obtained for 4 μm x 4 square portions.

Example 3 The photosensitive resin solution prepared in Example 1 was applied onto a polyester film so that the photoresist layer had a thickness of 1.5 μmK. The resist dry plate obtained in this way was
After pre-painting at 0℃ for 30 minutes, at 100℃ for 25 minutes.
Overpaid for a minute.

The microlithographic pattern is brought into close contact with this resist dry plate,
Exposure was carried out in the same manner as in Example 1 under vacuum contact. The irradiation dose was 5 units. After irradiation, this dry plate was treated with dioxa 15
The sample was immersed for 30 seconds in a mixed solvent at 20°C consisting of 35 parts of inzolobil alcohol and 35 parts of inzolobil alcohol.

Next, this dry plate was dried at 100° C. for 1 minute, allowed to cool at room temperature, and then developed by immersing it in an aqueous alkaline developer having the same composition as in Example 1 at 20° C. for 15 seconds. After development, the photoresist layer in the unexposed areas still remained on the polyester film when it was washed with water and dried.

Next, the entire surface of this dry plate was irradiated with 15 units in the same manner as in Example 1. When the depth of the relief pattern was measured with a stylus meter, the relief patterns with line widths of 5 μm, 3 μm, 1 μm, and 0.5 μm were all 0.9 μm.
The value of was obtained. The aspect ratio of 41 turns of Rely 7 with a line width of 0.5 μm was 1.8.

Example 4 The photosensitive resin solution prepared in Example 1 was applied onto a polyester film, and heat treated in the same manner as in Example 1 to obtain a resist dry plate with a photoresist layer having a thickness of 2.5 μm.

A 1982 Ugra test chart was brought into close contact with this resist dry plate, and exposed in the same manner as in Example 1 under vacuum contact. At that time, the irradiation dose was set to 5 units. After irradiation, this dry plate was developed by immersing it in a 20° C. aqueous alkaline developer having the same composition as in Example 1 for 30 seconds. After development,
When washed with water and dried, the photoresist layer remained in the unexposed areas with a thickness of 1.4 μm.

Next, the entire surface of this dry plate was irradiated with 15 units in the same manner as in Example 1. 20 pieces of the dry plate obtained in this way
℃ dioxane for 10 seconds. Next, this dry plate was washed with water and dried. When the depth of the relief pattern was measured with a stylus needle, it was 1.1 μm at the 4 μm patch part.
The value of was obtained.

Example 5 The thickness of the photoresist layer was 0.9 in the same manner as in Example 1.
A 5 μm resist dry plate was obtained.

The microlithographic pattern is brought into close contact with this resist dry plate,
Exposure was carried out in the same manner as in Example 1 under vacuum contact.

The irradiation dose was 100 units. After irradiation, the dry plate was immersed for 30 seconds in a mixed solvent of 5 parts of dioxane and 35 parts of Improvil alcohol at 20°C.

The dry plate was then dried at 100° C. for 1 minute, allowed to cool at room temperature, and then developed by immersing it in an aqueous alkaline developer having the same composition as in Example 1 at 20° C. for 30 seconds. After development, the photoresist layer in the unexposed areas still remained on the glass plate when it was washed with water and dried.

Next, the entire surface of this dry plate was irradiated with 15 units in the same manner as in Example 1. 20 pieces of the dry plate obtained in this way
℃ dioxane for 5 seconds. Next, this dry plate was washed with water and dried. When the depth of the relief pattern was measured using a stylus needle, a value of 0.95 μm was obtained for a relief pattern with a line width of 1 μm, and a value of 0.35 μm was obtained for a relief pattern with a line width of 0.5 μm.

Example 6 The photosensitive resin solution prepared in Example 1 was applied onto a polyester film so that the photoresist layer had a thickness of 1.5 μm. The Lenost dry plate obtained in this way was
After pre-painting at 0℃ for 30 minutes, at 100℃ for 25 minutes.
Overpaid for a minute.

A microlitho/l-turn was brought into close contact with this resist dry plate, and exposed in the same manner as in Example 1 under vacuum contact. The irradiation dose was 5 units. After irradiation, the plate was treated with a mixture of 5 parts dioxane and 35 parts Improvil alcohol at 20°C.
was immersed in a mixed solvent for 30 seconds.

Next, this dry plate was dried at 100° C. for 1 minute, allowed to cool at room temperature, and then developed by immersing it in a 20° C. aqueous alkaline developer having the same composition as in Example 1 for 30 seconds. After development, the photoresist layer in the unexposed areas still remained on the polyester film when it was washed with water and dried.

Next, the entire surface of this dry plate was irradiated with 15 units of radiation in the same manner as in Example 1. 20 pieces of the dry plate obtained in this way
℃ dioxane for 10 seconds. Next, this dry plate was washed with water and dried. When the depth of the relief pattern was measured with a stylus needle, lines @ 5 μm, 3 μm, and 1 μm were found.
and 0.5 μm relief pattern are both the same 0.9
Values in μm were obtained.

The aspect ratio of a relief pattern with a line width of 0.5 μm is 1.
．． 8 was shown.

〔Effect of the invention〕

When the method of the present invention is used to form a fine relief pattern using a negative photoresist, even with a relatively low exposure dose, a greater depth of relief/mother turn can be obtained than with conventional development methods without reducing resolution. be able to. That is, it is possible to form a fine relief pattern with a high aspect ratio expressed by the depth of the relief pattern relative to the line width of the relief pattern.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a resist dry plate with a thick photoresist layer 2 provided on a substrate 1. As shown in FIG. FIG. 2 is a cross-sectional view of a resist dry plate on which photocured portions 3 have been formed by exposure. FIG. 3 C: A relief pattern 4 and a continuous thin layer 5 that is integrated with the relief pattern and supports two turns of the relief pattern.
FIG. 2 is a cross-sectional view of a resist dry plate on which is formed. FIG. 4 is a cross-sectional view of a resist dry plate in which both the relief pattern and the continuous thin layer supporting the relief pattern are firmly crosslinked by full-surface exposure. DESCRIPTION OF SYMBOLS 1...Substrate, 2...Photoresist layer, 3...Photocuring part, 4...I) -7ノ! Turn, 5... Continuous thin layer supporting the relief pattern.

Claims (1)

[Claims] 1. (1) A first step of exposing a pattern to a resist dry plate formed by forming a negative photoresist layer on a substrate that can be developed with an aqueous alkaline developer; (2) Aqueous alkaline development; a second step of developing the photoresist layer with a solution to form a relief pattern and a continuous thin layer that is integrated with the relief pattern and supports the relief pattern; (3) exposing the entire surface of the developed photoresist layer to light; A method for forming an ultra-fine relief pattern, comprising a third step. 2. The method according to claim 1, wherein a polymer containing a phenylene diacrylate group and/or a cinnamic acid group in the main chain or side chain is used as the negative photoresist. 3. (1) A first step of exposing a pattern to a resist dry plate formed by forming a negative photoresist layer on a substrate that can be developed with an aqueous alkaline developer, and (2) immersing the photoresist layer in an organic solvent. (3) a third step of developing the photoresist layer with an aqueous alkaline developer to form a relief pattern and a continuous thin layer that integrates with and supports the relief pattern; 4) A method for forming an ultra-fine relief pattern, comprising a fourth step of exposing the entire surface of the developed photoresist layer to light. 4. The method according to claim 3, wherein a polymer containing a phenylene diacrylate group and/or a cinnamic acid group in the main chain or side chain is used as the negative photoresist. 5. The method according to claims 3 and 4, wherein a solvent that is a poor solvent for negative photoresist is used as the organic solvent. 6. The method according to claims 3 and 4, wherein a mixed solvent of a poor solvent and a good solvent is used for the negative photoresist as the organic solvent. 7. The method according to claims 3 to 6, wherein an organic solvent having a boiling point of 135° C. or lower is used as the organic solvent. 8. (1) A first step of exposing a pattern to a resist dry plate formed by forming a negative photoresist layer on a substrate that can be developed with an aqueous alkaline developer; and (2) exposing the photoresist layer with an aqueous alkaline developer. (3) a third step of exposing the entire surface of the developed photoresist layer to light; 4) A method for forming an ultra-fine relief pattern, comprising a fourth step of immersing the photoresist layer after the entire surface exposure in dioxane. 9. The method according to claim 8, wherein a polymer containing a phenylene diacrylate group and/or a cinnamic acid group in the main chain or side chain is used as the negative photoresist. 10. (1) A first step of exposing a pattern to a resist dry plate formed by forming a negative photoresist layer on a substrate that can be developed with an aqueous alkaline developer; (2) Immersing the photoresist layer in an organic solvent. (3) a third step of developing the photoresist layer with an aqueous alkaline developer to form a relief pattern and a continuous thin layer that integrates with and supports the relief pattern; 4) a fourth step of exposing the entire surface of the photoresist layer after the development; and (5) a fifth step of immersing the photoresist layer after the entire surface exposure in dioxane. Formation method. 11. The method according to claim 10, wherein a polymer containing a phenylene diacrylate group and/or a cinnamic acid group in the main chain or side chain is used as the negative photoresist. 12. The method according to claims 10 and 11, wherein a solvent that is a poor solvent for negative photoresist is used as the organic solvent. 13. The method according to claims 10 and 11, wherein a mixed solvent of a poor solvent and a good solvent is used for the negative photoresist as the organic solvent. 14. The method according to claims 10 to 13, wherein an organic solvent having a boiling point of 135° C. or lower is used as the organic solvent.