KR20060080884A - Method of removing the carbonate in a resist developer, devices for removing the same and method of managing the concentration of the resist developer - Google Patents

Abstract

An object of the present invention is to provide a method for removing carbonate from a resist developer containing TMAH and carbonate, an apparatus, and a method for managing the concentration of the resist developer. A method for removing carbonate in a resist developer according to the present invention includes a filtration step of filtering a resist developer containing TMAH and carbonate with an NF film.

Resist, Positive Resist, Negative Resist, Photolithography, Fractional Molecular Weight

Description

Method of removing the carbonate in a resist developer, devices for removing the same and method of managing the concentration of the resist developer

1 is a schematic flowchart of a resist developing system according to an embodiment of the present invention.

2 is a flowchart showing the filtration flow in the embodiment.

3 is a table showing the flow rates and the concentrations in Examples 1 to 3;

(Explanation of the sign)

40: NF film,

74: conductivity meter,

30A, 30B, 30C, 30D: Filtration device (filtration means)

14: carbonate removal apparatus.

The present invention relates to a method for removing carbonate in a resist developer, an apparatus, and a method for managing the concentration of a resist developer.

Conventionally, the photolithographic method is used abundantly in manufacture of an electronic device. In the said photolithographic method, after a predetermined light pattern is exposed to a photoresist, a latent image is formed, and the process of developing and patterning the said photoresist is performed. Usually, for this development, a resist developer containing tetramethylammonium hydroxide (hereinafter referred to as TMAH) is used. See Japanese Patent Laid-Open No. 5-11458, Japanese Patent Laid-Open No. 5-40345].

Since TMAH in the resist developer is consumed due to the resist development, deterioration of the developing performance of the resist developer occurs with the passage of the use time. In recent years, TMAH is supplemented with the resist developer at any time so that the conductivity of the resist developer is constant, so that the concentration of TMAH in the resist developer is kept constant, thereby extending the life of the resist developer while maintaining the developing performance of the resist developer. Therefore, the resist developer tends to be in contact with atmospheric gases such as air for a long time.

However, as a result of the inventor's examination, when the resist developer containing TMAH comes into contact with an atmospheric gas such as air for a long time, carbon dioxide in the atmosphere is dissolved in the resist developer and various carbonates, for example, TMA (tetra) It has been found that carbonates of methyl ammonium) and the like accumulate.

And when such carbonate accumulates in the resist developing solution, there exists a possibility that it may adversely affect the image development performance of a resist. In addition, since the carbonate of TMA is partially dissociated in the resist developer, the carbonate of TMA increases the conductivity of the resist developer. Therefore, even if TMAH is replenished in the resist developer so as to keep the conductivity of the resist developer constant, it may be difficult to precisely control the concentration of TMAH in the resist developer.

Therefore, there is a need to remove carbonates from the resist developer.

This invention is made | formed in view of the said subject, and an object of this invention is to provide the method of removing a carbonate from the resist developing solution containing TMAH and carbonate, an apparatus, and the density control method of a resist developing solution.

As a result of earnestly examining by the present inventors, when the resist developing solution containing TMAH and carbonate was filtered with a nanofiltration membrane, it discovered that the carbonate in a resist developing solution can be removed to a non-transmissive side, and came to this invention.

The removal method of the carbonate in the resist developing solution which concerns on this invention is equipped with the filtration process of filtering the resist developing solution containing TMAH (tetramethylammonium hydroxide) and carbonate with an NF membrane.

An apparatus for removing carbonate in a resist developer according to the present invention includes filtering means for filtering a resist developer containing TMAH and carbonate with an NF membrane.

According to the present invention, by filtering the resist developer containing TMAH and carbonate through the NF film, the carbonate concentration in the permeate is sufficiently reduced compared with the resist developer before filtration.

As the reason for such an effect being obtained, for example, water (molecular weight about 18) or TMAH (molecular weight about 91) can easily pass through the NF membrane having the above-mentioned fractional molecular weight, while carbonates such as TMA (tetra The carbonate (molecular weight of about 208) of methylammonium is predicted to have a three-dimensional structure, and it can be said that it is relatively difficult to pass through the NF film due to the increase in its structure and molecular weight.

Here, the fractional molecular weight of the NF film is preferably 500 to 1,500, and more preferably 700 to 1,000.

The method for managing the concentration of the resist developer according to the present invention is a process for removing carbonate from the resist developer using the method for removing carbonate in the resist developer described in any one of the above, and the TMAH concentration of the resist developer with the carbonate removed therefrom. The density | concentration measuring process measured with a vacuum gauge is provided.

Since the carbonate is partially dissociated in the resist developer, the presence of the carbonate deteriorates the precision in the measurement of the TMAH concentration using the conductivity meter, but according to the present invention, since the carbonate is removed in advance, the concentration of the TMAH in the resist developer is precisely determined. It can be measured.

According to the present invention, carbonate can be efficiently removed from the resist developer.

EMBODIMENT OF THE INVENTION Hereinafter, preferred embodiment of this invention is described, referring drawings. In addition, in the following description, the same code | symbol is attached | subjected to the same or equivalent part, and the overlapping description is abbreviate | omitted.

1 is a flowchart showing a developing system 10 according to the present embodiment.

The developing system 10 includes a resist developing device 12 for developing a photosensitive resist with a resist developing solution and a resist developing solution regenerating device 14 for regenerating a resist developing solution used for developing.

The resist developing apparatus 12 is an apparatus which develops the resist exposed by the well-known method with a resist developing solution, and the conventionally well-known resist developing apparatus 12 can be used.

As a resist used for image development, if it is a photosensitive resin material, it is good, for example, conventionally well-known positive resist composition, alkali-soluble resin, containing photosensitive agents, such as matrix resin, such as novolak resin, and naphthoquinone diazide, The conventionally well-known negative resist composition containing a photo-acid generator, a crosslinking agent, and a pigment can be used.

As a resist developer for developing such a resist, an alkaline resist developer containing TMAH (tetramethylammonium hydroxide) is used. Specifically, what contains 0.4-3.0 mass% of TMAH is used suitably as a resist developing solution, for example.

Subsequently, the resist developer regeneration device 14 will be described. The resist developer regeneration device 14 is a device that removes carbonate from the resist developer used in the resist developer 12 and adjusts the TMAH concentration of the resist developer. The resist developer regeneration device 14 mainly includes a reservoir tank 20, a plurality of filters 30A, 30B, 30C, 30D, and an adjustment tank 50.

The reservoir tank 20 is a container for storing the used resist developer discharged from the resist developing apparatus 12. The resist developer discharged from the resist developing apparatus 12 is stored in the reservoir tank 20 through the line L10 having the pump 22.

Filters (filtration means) 30A to 30D are devices for filtering the resist developer stored in the reservoir tank 20. Each of the filters 30A to 30D has an NF membrane 40, and a permeate liquid which has passed through the NF membrane 40 and a permeate liquid that has passed through the NF membrane 40 and the NF membrane 40 are passed through the resist developing solution to be filtered. The permeate is discharged from the permeate outlet p and the non-permeate is discharged from the non-permeate outlet u, respectively.

The NF membrane 40 is a separation membrane having a fractional molecular weight of about 200 to 2,000. In particular, in order to isolate | separate carbonate efficiently, it is preferable that fractional molecular weights are 500-1,500, and it is more preferable that fractional molecular weights are 700-1,000.

Here, the fractional molecular weight can be defined as the molecular weight at which the permeation inhibition rate is about 90%, for example, 5% sucrose solution (molecular weight of sucrose about 342), 0.1% dye solution (molecular weight of dye about 626), or the like. Pseudo measurement can be made from the transmittance curve measured using.

Subsequently, the connection relationship of the filter 30A-30D is explained in full detail. The reservoir tank 20 is connected to the inlet i of the filter 30A via the line L12 which has the pump 24 and the pump 26 in series.

The non-permeable liquid outlet u of the filter 30A is connected to the inlet i of the filter 30B via the line L14. The non-permeate outlet u of the filter 30B is also connected to the inlet i of the filter 30C via line L16, and the non-permeate outlet u of the filter 30C is also connected to the line L18. It is connected to the inlet j of the filter 30D via the inlet.

In addition, the non-permeable liquid outlet u of the filter 30D is connected between the pump 24 and the pump 26 in the line L12 via the line L20.

A line L22 having a valve V2 is branched from the line L20, and a drain tank 32 is connected to the line L22.

The permeate outlet p of the NF membrane 40 in each filter 30A-30D is connected to the adjustment tank 50 via the line L30, respectively.

The adjustment tank 50 is connected with the resist developing apparatus 12 by the line L40 which has the pump 52.

A resist developing stock solution supply system 60 is connected to the adjustment tank 50 through a line L50 having a valve V50, and a developing new solution supply system (line) through a line L52 having a valve V52. 62 is connected, and the pure water supply system 64 is connected via the line L54 which has the valve V54.

The resist developing stock solution supply system 60 is a TMAH supplying a resist developer of a predetermined high concentration, for example, 20% by weight, to the adjustment tank 50. In the resist developing new solution supply system 62, TMAH is a resist development. The resist developer set in advance to the concentration to be used in the apparatus 12 is supplied to the adjustment tank 50, and the pure water supply system 64 is to supply pure water to the adjustment tank 50.

The valve V50, the valve V52, and the valve V54 are connected to the control device 80, and the control device 80 controls each flow rate.

Moreover, the stirrer 70 which has the stirring blade 72 is provided in the adjustment tank 50, and the conductivity meter 74 which measures the electrical conductivity of the resist developing solution in the adjustment tank 50 is provided.

The conductivity meter 74 is connected to the control device 80, and the control device 80 has a predetermined TMAH concentration of the resist developer in the adjustment tank 50 based on the conductivity measured by the conductivity meter 74. Each flow rate is controlled to a concentration (for example, 2.38% by weight).

Next, the resist developing method by the developing system which concerns on this embodiment is demonstrated.

In the adjustment tank 50, the resist developing solution which TMAH becomes predetermined concentration, for example, 2.38 weight% is adjusted. Since such a process is well-known, the detail is abbreviate | omitted, but each liquid is adjusted in the adjustment tank 50 by the predetermined ratio from the resist developing solution supply system 60, the resist developing new solution supply system 62, and the pure water supply system 64. It can be performed easily by supplying.

And the resist developing solution in the adjustment tank 50 is supplied to the resist developing apparatus 12 by the pump 52, and the resist developing apparatus 12 develops the resist in which exposure was completed using the said resist developing solution.

As the development of the resist proceeds, TMAH in the resist developer is consumed. In addition, carbon dioxide in the atmosphere is dissolved in the resist developer and reacts with components such as TMAH in the resist developer to form various carbonates. For example, as the carbonate, there may be mentioned cations of TMAH that is a tetramethylammonium (TMA ⁺⁾ of the carbonate ion (TMA) ₂ CO ₃ in. The molecular weight of (TMA) ₂ CO ₃ is about 208.

In addition to this, in accordance with the development of the resist, the dissolved resist is also accumulated in the resist developer.

In this way, the resist developer in which TMAH was consumed and the carbonate and the dissolved resist were accumulated is stored in the reservoir tank 20 by the pump 22, and then, through the pump 24 and the pump 26, to the filter 30A. Supplied. Here, the resist developer is supplied to the filter 30A at a predetermined pressure by the pump 24 or the pump 26.

In the filter (30A), the carbonate in the resist developer solution (e. G., Molecular weight of about 208 (TMA) ₂ CO ₃₎ and dissolved resist is due to the difficulty of passing through the NF membrane 40, most of the carbonate or dissolved resist It is fed to filter 30B via line L14. On the other hand, since water (molecular weight about 18) and TMAH (molecular weight about 91) in the resist developer can sufficiently penetrate the NF film 40, these water and TMAH are NF depending on the pressure difference before and after the NF film 40. Water and TMAH, which permeate the membrane 40 and reach the control tank 50 through the line L30, are not permeated at the concentrate side, together with a carbonate or dissolved resist that could not permeate the NF membrane 40. It is supplied to 30B.

Also in the filter 30B, since the carbonate or the dissolving resist is difficult to penetrate the NF membrane 40, it is mainly supplied to the filter 30C through the line L16, while water or TMAH penetrates the NF membrane 40. Is supplied to the adjustment tank 50 via the line L30.

Similarly, the non-permeable liquid from the filter 30B is further filtered by each of the NF membranes 40 of the filter 30C and the filter 30D, and water and TMAH pass through the adjustment tank 50 through the line L30. ), While a non-permeable liquid comprising carbonate, dissolved resist, water and TMAH is recycled to line L12 via line L20.

In addition, a portion of the non-permeable liquid from the filter 30D is discharged to the drain tank 32 through the line L22. For example, the carbonate concentration or the resist concentration on the non-transmissive side of the NF film 40 is too high. It is not to be supported.

In the adjustment tank 50, the conductivity of the developing developer, that is, the conductivity of the permeate mainly containing water and TMAH is measured by the conductivity meter 74, so that the developer stock solution returns the concentration of TMAH to a predetermined set value. The developing new solution and water are supplied to the adjustment tank alone or in any combination, and the liquid is stirred by the stirring blade 72 to regenerate a resist developer having a desired TMAH concentration. And the resist developing solution reproduced in this way is returned to the resist developing apparatus 12 via the line L40.

According to this system, since the used developer in which the carbonate or the dissolved resist is accumulated by the developing operation in the resist developing apparatus 12 is filtered through the NF film 40, the carbonate or the dissolved resist can be removed from the permeate. Can be. Since the permeate is returned to the resist developing apparatus 12 through the adjustment tank 50 and used as a resist developer, deterioration in developing performance of the resist developer due to an increase in carbonate, dissolved resist, or the like can be suppressed. have.

In addition, in the adjustment tank 50, TMAH density | concentration in the filtrate from which the carbonate etc. were removed is measured by the conductivity meter 74. As shown in FIG. Since carbonate is partially ionized in the resist developer, the presence of a large amount of carbonate in the adjusting tank 50 prevents the measurement of the TMAH concentration using a conductivity meter. However, according to the present invention, since the carbonate is removed before the measurement of the conductivity, the TMAH concentration of the resist developer can be measured precisely. Therefore, the adjustment and management of TMAH density | concentration in the adjustment tank 50 by the control apparatus 80 can be made precisely, and the image development in the resist developing apparatus 12 which reuses this can be performed more suitably.

In addition, this invention is not limited to the said embodiment, A various deformation | transformation is possible.

For example, in the said embodiment, although the some filter 30A-30D is connected in series, even if a single filter is operable, it is also possible to connect a some filter in parallel.

Example

Then, the usefulness of this invention is shown based on an Example. Here, as shown in FIG. 2, with respect to one filtration device 30A, a resist developer which has been used for development is supplied through line L100, and from filtration device 30A through line L104. The permeate was discharged, and a part of the non-permeate was recycled to the line L100 through the line L102, and the rest of the non-permeate was discharged through the line L103. Herein, the flow rate of the resist developer supplied to the inlet of the line L100 is Q _in , and the flow rate of the resist developer discharged from the outlet of the line L104 is Q _per , and is recycled to the line L100 through the line L102. The flow rate of the resist developer is Q _r , and the flow rate of the resist developer discharged through the line L103 is Q _out .

Here, the fractional molecular weight of the NF film 40 was 1,000.

In Example 1, the used resist developer which developed the novolak-type resist using the resist developer containing 2.38% of TMAH was supplied as Qin to the inlet of the line L100. In Example 2, the used resist developer which developed the novolak-type resist using the resist developer containing 2.379% of TMAH was supplied as Q _in to the inlet of the line L100. In addition, in Example 3, the used resist developer which developed the acrylic resist using the resist developer containing 0.471% of TMAH was supplied as Q _in to the inlet of the line L100.

Then, the filtration is shown in each flow chart _in Q, Q _{out, per} Q, Figure 3 a flow rate and concentration of _r Q after the summit is reached. Here, the carbonate concentration was determined by ion chromatography, the inactivated TMAH concentration and the active TMAH concentration were determined by hydrochloric acid titration, and the dissolved resist concentration was determined by dry weight method. Formation of carbonate is thought to occur as an increase in carbonate ions and also as an increase in deactivation TMAH. In addition, it is considered that the deactivation of TMAH also contributes to the reaction with other resists of carbonate formation.

As can be seen from FIG. 3, the carbonate ion concentration and the deactivation TMAH concentration of the permeate Q _per are significantly lower than the respective concentrations of the feed liquid Q _in , while the carbonate ion concentration and the deactivation TMAH concentration of the non-permeate discharge Q _out are significantly lower. It was elevated. In addition, the dissolution resist also showed a tendency equivalent to the carbonate concentration. On the other hand, the active TMAH concentration did not change so much among Q _in , Q _per , and Q _out .

According to the present invention, the resist developer containing tetramethylammonium hydroxide and carbonate is filtered through an NF membrane, whereby the carbonate concentration in the permeate is sufficiently reduced as compared with the resist developer before filtration and the carbonate is removed in advance. The concentration of TMAH can be measured precisely.

Claims (4)

A method for removing carbonate in a resist developer, comprising a filtration step of filtering a resist developer containing tetramethylammonium hydroxide and a carbonate with a nanofiltration membrane. The method for removing carbonate in a resist developer according to claim 1, wherein the fractional molecular weight of the NF film is 500 to 1,500. Removing the carbonate of the resist developer using the method for removing the carbonate in the resist developer according to claim 1; A density control method of a resist developer, comprising a concentration measuring step of measuring a tetramethylammonium hydroxide concentration of a resist developer in which a carbonate is removed with a conductivity meter. An apparatus for removing carbonate in a resist developer, comprising filtering means for filtering a resist developer containing tetramethylammonium hydroxide and carbonate with an NF film.

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