JP2013120341A - Production method of recycled resist and recycle usage of resist - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production method of recycled resist having a high storage stability, and provide a recycle usage of resist.SOLUTION: If a solvent of a used resist is mainly composed of propylene glycol monomethyl ether acetate (PGMEA) and a rinse liquid contains another solvent having the boiling temperature lower than the PGMEA, a used mixture containing the used resist and a waste liquid of the rinse liquid is recovered and concentrated, and then a recycled resist is prepared by adding an unused resist to a concentrated liquid so that a percentage of the unused resist is 20 mass% or more. Consequently, the recycled resist can be produced which is hard to generate foreign matters after a long-term storage and can form a resist film comparable to the unused resist. By using such a method, the resist can be used multiple times.

Description

  The present invention relates to a method for producing a regenerated resist and a method for recycling the resist.

  In a manufacturing process of a semiconductor, a liquid crystal panel, or the like, lithography is performed in which a resist (resist solution) is applied on a substrate and exposed and developed. With the recent increase in size of liquid crystal panels and the like, the amount of resist used is also increasing because the size of substrates used has been increasing. Typical coating methods include a spin coating method and a die coating (slit coating) method.

  In the application of the resist to the substrate, an excessive amount of resist more than the amount of resist actually remaining as a film on the substrate is required, so that an excessive used resist is always generated. Since the amount of used resist is not negligible, it is economically and environmentally desirable to collect and recycle it.

  Several proposals have been made regarding the collection and recycling of used resist. For example, a method of collecting a resist scattered at the time of spin coating, recovering the collected resist by dissolving it with a resist solvent, performing filtration and vacuum distillation treatment (see Patent Document 1), resist coating apparatus A method of regenerating the cleaning liquid composed of the resist and the cleaning liquid composed of the same components as the resist solvent by adjusting the viscosity by evaporating the solvent component has been proposed (see Patent Document 2). Furthermore, the present inventors, as a method for producing a regenerated resist that can reuse the resist even if the resist solvent and the rinsing liquid are different components, include a step of fractionating a specific solvent to a predetermined concentration or less. The method (refer patent document 3) including is proposed.

JP-A-9-34121 JP-A-11-245226 JP 2010-237624 A

  However, it has been found that when the recycled resist is repeatedly recycled by the method of Patent Document 3, there is a problem in storage stability such as generation of foreign matters during long-term storage.

  The present invention has been made in view of the above problems, and an object thereof is to provide a method for producing a regenerated resist having high storage stability and a method for recycling the resist.

  As a result of intensive studies to achieve the above object, the present inventors collect a used mixed solution including a used resist and a waste solution of a rinsing solution, concentrate it, and then add a predetermined amount of an unused resist. Thus, it was found that a regenerated resist having excellent long-term storage stability can be produced, and the present invention has been completed.

  A first aspect of the present invention is a method for producing a regenerated resist in which a remaining used resist is collected after the resist is applied, and a regenerated resist is produced from the used resist. A recovery step for recovering a used mixed solution, a concentration step for concentrating the used mixed solution to prepare a concentrated solution, and a ratio of unused resist to 20% by mass or more. A regenerated resist preparation step of preparing a regenerated resist by adding an unused resist to the concentrate, wherein the solvent of the used resist is mainly propylene glycol monomethyl ether acetate, and the rinse liquid is from propylene glycol monomethyl ether acetate This is a method for producing a regenerated resist containing another solvent having a low boiling point.

  The second aspect of the present invention includes a supply step of supplying a resist from a resist storage tank to a resist coating device, a coating step of coating the resist on a substrate in the resist coating device, and the remaining used resist and rinsing liquid. A recovery step for recovering a used mixed solution, a concentration step for concentrating the used mixed solution to prepare a concentrated solution, and a ratio of unused resist to 20% by mass or more. A regenerated resist preparation step of preparing a regenerated resist by adding an unused resist to the concentrate, and a storage step of storing the regenerated resist in the resist storage tank, wherein the solvent of the used resist is mainly propylene glycol monomethyl Ether acetate, and the rinse liquid has a lower boiling point than propylene glycol monomethyl ether acetate. Include other solvents, it is recycled use of the resist.

  According to the present invention, it is possible to manufacture and recycle a recycled resist that can form a resist film that hardly forms foreign matter even after long-term storage and can form a resist film that is not inferior to an unused resist even after being recycled a plurality of times.

It is a flowchart which shows an example of the manufacturing method of the reproduction | regeneration resist of this invention. It is a flowchart which shows an example of the recycling usage method of the resist of this invention. 6 is a graph showing the relationship between the line width and the exposure time in the regenerated resist of Example 1 and the resist of Reference Example.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a basic flowchart of a method for producing a regenerated resist according to the present invention. Hereinafter, the present invention will be described with reference to FIG.

[Recycled resist manufacturing method]
[Recovery process]
The recovery step S10 is a step of recovering the used mixed liquid including the used resist and the rinsing liquid waste liquid.

  When a resist is applied on the substrate, there is a residual resist that does not remain as a film on the substrate but is generated by scattering or dropping in the coating apparatus. These are collected as used resist. The resist can be applied by using a known method such as a spin coat method, a roll coater method, a bar coater method or the like.

  The resist used in the present invention is a composition obtained by dissolving a conventionally known resist component including at least a base resin component in an organic solvent mainly composed of propylene glycol monomethyl ether acetate (PGMEA). Of course, either a positive resist or a negative resist may be used, and a conventionally known compound such as an acid generator, a sensitizer, a photosensitizer, and a surfactant may be included as necessary. The concentration of PGMEA may be 50% or more, preferably 60% or more, and more preferably 80% or more. Even if it is an unused resist, the reproduction | regeneration resist manufactured by the method of this invention may be sufficient.

  After the application of the resist, a waste solution containing unnecessary portions of the resist film and a rinse solution, which is generated by subsequent cleaning such as edge rinse and back rinse, is further collected. What contains these waste liquids and the used resist is a used mixed liquid. The rinsing method is not particularly limited, such as a dipping method or a spray method, and the rinsing liquid treatment time is not particularly limited as long as it is a time sufficient for washing and removing unnecessary portions.

  The rinse liquid used in the present invention contains another solvent having a boiling point lower than that of PGMEA (boiling point 146 ° C.). Examples of the other solvent include propylene glycol monomethyl ether having a boiling point of 120 ° C., butyl acetate having a boiling point of 126 ° C., and methyl-3-methoxypropionate having a boiling point of 142 ° C. In order to prevent a fractional distillation rate from decreasing in the concentration step described later, the boiling point difference with PGMEA is preferably large, the boiling point difference of 10 ° C. or higher is preferable, and the boiling point difference of 20 ° C. or higher is more preferable. These rinsing solutions may be used alone or in combination.

[Concentration process]
The concentration step S11 is a step of obtaining a concentrated solution from the used mixed solution by concentrating the other solvent so as to have a predetermined concentration or less. Since the other solvent has a lower boiling point than PGMEA, the concentration can be lowered by concentration. The concentration in the present invention does not mean complete rectification but means a chemical operation in which other solvents are reduced to a predetermined ratio using a difference in boiling points. This concentration step S11 is preferably performed not on the user side with the coating apparatus but on the resist manufacturer side because it is preferable to manage the solvent composition after concentration.

  The concentration method is not particularly limited. For example, the concentration is performed by evaporating the other solvent by heating the used mixed liquid while stirring. Further, if necessary, the used mixed solution may be heated while stirring to evaporate the other solvent. Further, PGMEA may be re-added as necessary to facilitate evaporation of the other solvent.

  In the concentration step S11, the degree of concentration can be appropriately set according to the purpose of use of the regenerated resist. However, it is preferable that the concentration is such that the concentration of the other solvent in the total solvent is 40% or less. More preferably, it is 10% or less, More preferably, it is 1% or less. If the concentration of the other solvent is 40% or less, it can be used as a regenerated resist in applications according to the required performance. For the same reason, the concentration of PGMEA is preferably 50% or more.

  In the concentration step S11, the concentration of the other solvent can be reduced to 40% or less by a single concentration. However, the concentration of the other solvent can be further reduced by performing the concentration step S11 a plurality of times. Can do. As a result, the concentration of the other solvent can be freely changed to some extent, can be used for the production of various forms of regenerated resist, and can meet user requirements.

[Recycled resist preparation process]
The regenerated resist preparation step S12 is a step of preparing a regenerated resist by adding an unused resist to the concentrated solution. By adding an unused resist, an effect of suppressing the generation of foreign matters can be obtained in long-term storage.

Here, foreign matter generated after long-term storage can be detected as the number of particles per unit volume by a particle counter, but as the number of particles increases, a uniform resist film cannot be formed and used as a resist. become unable. There is a close relationship between the probability of particle generation and the concentration of high molecular weight components in GPC analysis. It has been found that a large number of particles are generated, resulting in performance degradation such as a decrease in resist sensitivity, which makes it impossible to use as a resist.
Here, the high molecular weight component peak in GPC analysis is a peak detected on the higher molecular weight side than the main peak of the base resin component contained in the resist.
Specifically, the high molecular weight component peak in the GPC analysis can be measured, for example, under the following conditions, and appears at a position of 15.5 to 18.3 minutes.
Apparatus: Shodex SYSTEM 21 (manufactured by Showa Denko)
Guard column: Shodex KF-G
Column: Shodex KF-801 × 3
Detector: Shodex UV 41
Detection wavelength: 310 nm
Eluent: Tetrahydrofuran (THF)
Flow rate: 1.0 mL / min Sample concentration: THF solution with a solid content concentration of 0.2% by mass for each resist composition

  Table 1 shows an example of recycling the resist by the method of Patent Document 3. Even if it is a normally unused resist, the GPC high molecular weight component peak is present in 4 to 6 area%, but it is regenerated in about 3 times if recycling is repeated by concentrating the used mixed solution by the method of Patent Document 3. The GPC high molecular weight component peak immediately after the resist preparation exceeds 10 area%, and after 6 months, the number of particles of 0.3 μm or more exceeds 10,000 particles / mL, making it unsuitable for use as a resist.

  However, if an unused resist is added to the concentrated solution so that the GPC high molecular weight component peak immediately after the preparation of the resist is 10 area% or less, the resist can be stably used even after storage for 6 months. As the amount of unused resist added increases, long-term storage stability increases, but the cost increases. Therefore, the lower limit of the amount added was determined by simulation. It was assumed that the GPC high molecular weight component peak of the unused resist was 6 area% and increased by 1 area% after the concentration step, and the state in which the area% of the high molecular weight component changed with recycling was calculated. Tables 2 to 4 show cases in which an unused resist is added to the concentrate and the ratio of the unused resist in the recycled resist is 10%, 15%, and 20%.

  As shown in Table 4, if the unused resist is added so that the GPC high molecular weight component peak of the unused resist is 6 area% and the ratio of the unused resist in the recycled resist is 20%, the GPC height of the recycled resist is increased. It is understood that the area% of the molecular weight component peak is 10% for the first time when the recycling is performed 40 times, and the recycling is possible after that. On the other hand, as shown in Tables 2 and 3, when the amount of unused resist added is small, the number of recyclings does not increase so much. If the area percentage of the GPC high molecular weight component peak of the unused resist is originally lower than 6%, the number of recyclables increases. If the amount of unused resist added to the concentrate increases, the number of recyclables increases.

  In view of cost, it is preferable that the amount of the unused resist added is appropriately set according to the required performance of each application within a range where the ratio of the unused resist in the recycled resist is 20% by mass or more and 50% by mass or less. . After the unused resist is added, a solvent used for the unused resist may be added separately in order to adjust the solid content concentration of the regenerated resist.

[Recycling usage of resist]
A method for recycling a resist according to another embodiment of the present invention will be described with reference to the drawings. FIG. 2 is a basic flowchart of a method for recycling a resist according to the present invention. Hereinafter, the present invention will be described with reference to FIG.

[Supply process]
The supplying step S20 is a step of supplying the resist from the tank storing the resist to the resist coating apparatus. Here, the resist is mainly a recycled resist, but it may be an unused resist at the start of the cycle.

[Coating process]
The coating step S21 is a step of coating the resist on the substrate in the resist coating apparatus. As a coating method, a known method such as a spin coat method, a roll coater method, or a bar coater method can be used. For example, the coating step S21 can be performed by an apparatus provided with means for relatively moving the discharge nozzle and the substrate. The discharge nozzle is not particularly limited as long as it is configured so that the resist is applied onto the substrate. For example, a discharge nozzle having a plurality of nozzle holes arranged in a row or a slit A discharge nozzle having a shape-like discharge port can be used. Further, the coating step S21 can use means for adjusting the film thickness to be thin by spinning the substrate after discharging the resist onto the substrate.

  In this coating step S21, for example, in a large resist coating apparatus such as a semiconductor or liquid crystal panel production line, a large amount of residual resist solution after coating is generated.

  The collection step S22, the concentration step S23, and the regenerated resist preparation step S24 are as described in the recovery method manufacturing method for the regenerated resist as the recovery step S10, the concentration step S11, and the regenerated resist preparation step S12.

[Storage process]
The storage step S25 is a step of storing the regenerated resist prepared in the regenerated resist preparation step in a resist storage tank. The regenerated resist is preferably stored in a resist storage tank adjusted to a temperature of 0 to 20 ° C. The stored regenerated resist is preferably used in the supplying step S20 usually within 6 months.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these.

[Recycled resist manufacturing method]
Example 1
A used mixed solution (solid content concentration 11%, moisture 3) containing a used resist generated when applied to a substrate using TFR-970PM manufactured by Tokyo Ohka Kogyo Co., Ltd. and butyl acetate used as a rinsing liquid %, PGMEA 20% in organic solvent, 80% butyl acetate in organic solvent).
The used mixture was heated to 70-80 ° C. and concentrated to about 1/3. To this, PGMEA was added in the same amount as the whole liquid, heated again to 70-80 ° C., and concentrated to about １ ／. Furthermore, PGMEA was added in half of the total liquid volume, heated to 70-80 ° C. and concentrated (solid content concentration 45%, moisture 0.04%, PGMEA 98% in organic solvent, butyl acetate 2% in organic solvent, ) To this concentrate, unused TFR-970 PM of the same weight was added, and further, PGMEA was added so as to have a solid content concentration of 23.6% to prepare a regenerated resist A.
The used mixed liquid containing the used resist and the rinse liquid waste generated when the regenerated resist A is applied to the substrate is concentrated in the same manner to obtain a concentrated liquid (solid content 42%, moisture 0.06%). , PGMEA 99% in organic solvent, butyl acetate 1% in organic solvent). To this concentrate, unused TFR-970 PM of the same weight was added, and further, PGMEA was added to adjust the solid content concentration to prepare a regenerated resist B.
Similarly, after using the regenerated resist B for substrate coating, the used mixed solution is recovered and concentrated to a solid content concentration of 41%, moisture of 0.05%, PGMEA in organic solvent 99%, and acetic acid in organic solvent. A concentrated solution of 1% butyl was prepared, and unused TFR-970 PM of the same weight was added thereto. Further, PGMEA was added to adjust the solid content concentration to prepare a regenerated resist C. The same process was repeated to prepare recycled resists D and E.
Table 5 shows the component concentration, viscosity, and area percentage of the GPC high molecular weight component peak immediately after preparation of unused TFR-970PM (reference example) and recycled resists A to E.

[Resist film evaluation]
(Example 2)
Unused TFR-970PM (reference example) and regenerated resists A to E immediately after preparation were applied on a HMDS-treated silicon substrate and then pre-baked at 90 ° C. for 90 seconds to form a 1.6 μm thick resist film did. Then, after exposing with the exposure apparatus (brand name: MPA-600FA made from Canon) by the line and space 1: 1 through the mask pattern of 3 micrometers line / 3 micrometers space, the post-baking was performed 90 degreeC * 90 second. Next, development was performed with a 2.38 mass% tetramethylammonium hydroxide aqueous solution for 100 seconds, and unnecessary portions were removed through rinsing with pure water to obtain a pattern.
The illuminance was kept constant at 500 mW / cm ² , the exposure time (ms) was changed, and the relationship with the obtained measured line width was evaluated. The results are shown in FIG. It can be seen that the regenerated resists A to E are not significantly different from the unused resist and can be used sufficiently.

[Storage stability evaluation]
(Example 3)
The unused TFR-970PM (reference example) and the regenerated resists A to E were evaluated for various performances immediately after preparation and when stored at 20 ° C. after 3 months and after 6 months.

  Table 6 shows the number of particles of 0.3 μm or more per 1 mL (number / mL) detected by the particle counter.

Table 7 shows changes in resist sensitivity (E _th ) (mJ / cm ² ). Unused TFR-970PM (reference example) and regenerated resists A to E immediately after preparation were applied on a HMDS-treated silicon substrate and then pre-baked at 110 ° C. for 90 seconds to form a resist film having a thickness of 1.52 μm. did. Then, it exposed through the pattern with the exposure apparatus (brand name: G7E made from Nikon). Next, development was performed for 65 seconds with an aqueous 2.38 mass% tetramethylammonium hydroxide solution, and unnecessary portions were removed through rinsing with pure water to obtain a pattern. The relative value between the exposure amount at which the unnecessary portion disappears and the STD value (standard sample exposure amount) is shown in%. The resist used as the standard sample is a frozen sample of TFR-970PM. In Table 7, the result immediately after the preparation is a comparison between the exposure amount of the regenerated resist immediately after the preparation and the exposure amount of the standard sample. Thereafter, the regenerated resist and the like were stored at 20 ° C., and the standard sample was stored frozen, and the same evaluation was performed after 3 months and 6 months.

  Table 8 shows changes in film slip. Unused TFR-970PM (reference example) and regenerated resists A to E immediately after preparation were applied on a HMDS-treated silicon substrate and then pre-baked at 110 ° C. for 90 seconds to form a resist film having a thickness of 1.52 μm. did. Then, it exposed through the pattern with the exposure apparatus (brand name: G7E made from Nikon). Next, development was performed for 65 seconds with an aqueous 2.38 mass% tetramethylammonium hydroxide solution, and unnecessary portions were removed through rinsing with pure water to obtain a pattern. Next, the film thickness of the unexposed part was measured. The relative value between the film thickness value and the STD value (standard film thickness value) is shown in%. The resist used as the standard sample is a frozen sample of TFR-970PM. In Table 8, the result immediately after the preparation is a comparison between the film thickness of the regenerated resist immediately after the preparation and the film thickness of the standard sample. Thereafter, the regenerated resist and the like were stored at 20 ° C., and the standard sample was stored frozen, and the same evaluation was performed after 3 months and 6 months.

  It can be seen that the regenerated resists A to E are less likely to generate particles even after storage for 6 months, have little change in sensitivity and film slip, and can be used as resists.

S10 Recovery process S11 Concentration process S12 Regenerated resist preparation process S20 Supply process S21 Application process S22 Recovery process S23 Concentration process S24 Regenerated resist preparation process S25 Storage process

Claims (4)

After applying the resist, the remaining used resist is collected, and a regenerated resist manufacturing method for manufacturing a regenerated resist from the used resist,
A recovery step of recovering a used mixed solution, including the used resist and a rinsing liquid waste solution;
A concentration step of concentrating the used mixed solution to prepare a concentrated solution;
A regenerated resist preparation step of preparing a regenerated resist by adding an unused resist to the concentrate so that the ratio of the unused resist is 20% by mass or more;
Including
The solvent of the used resist is mainly propylene glycol monomethyl ether acetate,
The rinse liquid contains another solvent having a boiling point lower than that of propylene glycol monomethyl ether acetate,
A method for producing a regenerated resist.   The method for producing a regenerated resist according to claim 1, wherein the other solvent is one or more solvents selected from propylene glycol monomethyl ether, butyl acetate, and methyl-3-methoxypropionate.   3. The method for producing a regenerated resist according to claim 1, wherein in the concentration step, the used mixed solution is concentrated so that a ratio of the other solvent in the total solvent is 40% by mass or less. A supply process for supplying the resist from the resist storage tank to the resist coating apparatus;
A coating step of coating the resist on a substrate in the resist coating apparatus;
A recovery step for recovering the used mixed solution including the remaining used resist and the waste liquid of the rinse solution;
A concentration step of concentrating the used mixed solution to prepare a concentrated solution;
A regenerated resist preparation step of preparing a regenerated resist by adding an unused resist to the concentrate so that the ratio of the unused resist is 20% by mass or more;
Storing the recycled resist in the resist storage tank;
Including
The solvent of the used resist is mainly propylene glycol monomethyl ether acetate,
The rinse liquid contains another solvent having a boiling point lower than that of propylene glycol monomethyl ether acetate,
How to recycle resist.

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