JP2006189646A - Method for removing carbonate in resist developing solution, removing device, and method for controlling concentration of resist developing solution - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and a device for removing carbonates from a resist developing solution containing TMAH (tetramethylammonium hydroxide) and carbonates, and to provide a method for controlling the concentration of a resist developing solution. <P>SOLUTION: The method for removing carbonates in the resist developing solution includes a filtration step of filtering a resist developing solution containing TMAH and carbonates through an NF (nano filtration) membrane. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

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

Conventionally, a photolithography method is often used in the manufacture of electronic devices. In this photolithography method, a predetermined optical pattern is exposed on the photoresist to form a latent image, and then the photoresist is developed and patterned. Usually, a resist developer containing tetramethylammonium hydroxide (hereinafter referred to as TMAH) is used for such development (see, for example, Patent Documents 1 and 2).
JP-A-5-11458 JP-A-5-40345

  Since TMAH in the resist developer is consumed as the resist is developed, the development performance of the resist developer deteriorates with the passage of time. In recent years, TMAH is replenished to the resist developer as needed so that the conductivity of the resist developer is constant, so that the concentration of TMAH in the resist developer is kept constant, while maintaining the development performance of the resist developer. The life of the liquid has been extended. Therefore, the resist developer tends to come into contact with an atmospheric gas such as air for a long time.

  However, the inventors have examined that 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 dissolves in the resist developer, and various carbonates are contained in the resist developer. For example, it has been found that carbonates of TMA (tetramethylammonium) and the like accumulate.

  If such carbonates accumulate in the resist developer, the development performance of the resist may be adversely affected. Further, since TMA carbonate is partially dissociated in the resist developer, the TMA carbonate increases the conductivity of the resist developer. Therefore, even if the resist developer is supplemented with TMAH so as to keep the conductivity of the resist developer constant, it may be difficult to accurately control the concentration of TMAH in the resist developer.

  Therefore, it is necessary to remove the carbonate from the resist developer.

  The present invention has been made in view of the above problems, and an object thereof is to provide a method, an apparatus, and a resist developer concentration management method for removing carbonate from a resist developer containing TMAH and carbonate.

  As a result of intensive studies by the present inventors, it has been found that if a resist developer containing TMAH and carbonate is filtered through an NF film, the carbonate in the resist developer can be removed to the non-permeating side, and the present invention has been conceived. It was.

  The method for removing carbonate in a resist developer according to the present invention includes a filtration step of filtering a resist developer containing TMAH (tetramethylammonium hydroxide) and carbonate through an NF membrane.

  The apparatus for removing carbonate in a resist developer according to the present invention includes a filtering means for filtering a resist developer containing TMAH and carbonate through an NF film.

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

  The reason why such an effect is obtained is that, for example, water (molecular weight of about 18) and TMAH (molecular weight of about 91) can easily pass through the above-mentioned NF membrane of the molecular weight cut off, while carbonates such as TMA (tetra Methylammonium) carbonate (molecular weight of about 208) is also predicted to have a three-dimensional structure, and it is relatively difficult to pass through the NF membrane due to the increase in the structure and molecular weight.

  Here, the molecular weight cutoff of the NF film is preferably 500 to 1500, and more preferably 700 to 1000.

  The resist developer concentration management method according to the present invention includes a step of removing carbonate in a resist developer using the method for removing carbonate in a resist developer as described above, and the carbonate is removed. And a concentration measuring step of measuring the TMAH concentration of the resist developer with a conductivity meter.

  Since carbonate is partially dissociated in the resist developer, the presence of carbonate deteriorates accuracy in the measurement of TMAH concentration using a conductivity meter. However, according to the present invention, carbonate is removed in advance. The concentration of TMAH in the resist developer can be accurately measured.

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

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In the following description, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted.

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

  The developing system 10 includes a resist developing device 12 that develops the exposed resist with a resist developer, and a resist developer reproducing device 14 that regenerates the resist developer used for development.

  The resist developing device 12 is a device for developing a resist exposed by a known method with a resist developer, and a conventionally known resist developing device 12 can be used.

  The resist to be developed may be a photosensitive resin material. For example, a conventionally known positive resist composition containing a matrix resin such as a novolak resin and a photosensitizer such as naphthoquinone diazide, an alkali-soluble resin, a photoacid, and the like. A conventionally known negative resist composition containing a 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, for example, a resist developer containing 0.4 to 3.0% by mass of TMAH is suitably used.

  Next, the resist developer reproducing apparatus 14 will be described. The resist developer regenerating apparatus 14 is an apparatus 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 30 </ b> A, 30 </ b> B, 30 </ b> C, 30 </ b> D, and an adjustment tank 50.

  The reservoir tank 20 is a tank that stores used resist developer discharged from the resist developing device 12. The resist developer discharged from the resist developing device 12 is stored in the reservoir tank 20 via a line L10 having a pump 22.

  Filters (filtering means) 30 </ b> A to 30 </ b> D are devices that filter the resist developer stored in the reservoir tank 20. Each of the filters 30A to 30D has an NF film 40. The resist developer that is to be filtered flowing in from the inlet i is passed through the NF film 40 and the non-permeate that does not pass through the NF film 40. Then, the permeate is discharged from the permeate outlet p and the non-permeate is discharged from the non-permeate outlet u.

  This NF membrane 40 is a separation membrane having a fractional molecular weight of about 200 to 2,000. In particular, in order to efficiently separate the carbonate, the molecular weight cut off is preferably 500 to 1500, and the molecular weight cut off is more preferably 700 to 1000.

  Here, the molecular weight cut off can be defined as a molecular weight with a permeation blocking rate of about 90%. For example, a 5% sucrose solution (sucrose molecular weight of about 342) or a 0.1% dye solution (dye molecular weight of about 626). ) And the like can be used for pseudo measurement from the transmittance curve.

  Next, the connection relationship between the filters 30A to 30D will be described in detail. The reservoir tank 20 is connected to the inlet i of the filter 30A via a line L12 having a pump 24 and a pump 26 in series.

  The non-permeate outlet u of the filter 30A is connected to the inlet i of the filter 30B via a line L14. The non-permeate outlet u of the filter 30B is further connected to the inlet i of the filter 30C via the line L16, and the non-permeate outlet u of the filter 30C is further connected to the filter 30D via the line L18. Connected to inlet i.

  The non-permeate 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 further branches 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 of the filters 30A to 30D is connected to the adjustment tank 50 via a line L30.

  The adjustment tank 50 is connected to the resist developing device 12 by a line L40 having a pump 52.

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

  The resist developing stock solution supplying system 60 supplies a resist developing solution having a predetermined high concentration of TMAH, for example, 20 wt%, to the adjustment tank 50, and the resist developing new solution supplying system 62 is a TMAH using the resist developing device 12. A resist developing solution set in advance to a concentration to be used is supplied to the adjustment tank 50, and a pure water supply system 64 supplies 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.

  Further, the adjustment tank 50 is provided with a stirrer 70 having a stirring blade 72 and a conductivity meter 74 for measuring the conductivity of the resist developer in the adjustment tank 50.

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

  Next, a resist development method using the development system according to the present embodiment will be described.

  In advance, in the adjustment tank 50, a resist developer having a predetermined concentration of TMAH, for example, 2.38 wt% is adjusted. Although this process is well known and will not be described in detail, each solution is supplied into the adjustment tank 50 from the resist developing stock solution supply system 60, the resist development new solution supply system 62, and the pure water supply system 64 at a predetermined ratio. This can be done easily.

  Then, the resist developing solution in the adjustment tank 50 is supplied to the resist developing device 12 by the pump 52, and the resist developing device 12 develops the exposed resist using the resist developing solution.

As the development of the resist proceeds, TMAH in the resist developer is consumed. Further, carbon dioxide in the atmosphere dissolves in the resist developer and reacts with components such as TMAH in the resist developer to form various carbonates. For example, the carbonate includes (TMA) ₂ CO ₃ which is a cation of TMAH, that is, a carbonate of tetramethylammonium (TMA ⁺ ) ion. (TMA) ₂ CO _{3 has} a molecular weight of about 208.

  In addition, with the development of the resist, the dissolved resist also accumulates in the resist developer.

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

In the filter 30A, carbonate (for example, (TMA) ₂ CO ₃ having a molecular weight of about 208) or dissolved resist in the resist developer hardly permeate the NF film 40, so that most of the carbonate and dissolved resist are line L14. Is supplied to the filter 30B. On the other hand, water (molecular weight of about 18) and TMAH (molecular weight of about 91) in the resist developer can sufficiently permeate the NF film 40, so that these water and TMAH pass through the NF film 40 according to the pressure difference before and after the NF film 40. Permeate and reach the adjustment tank 50 via the line L30. On the other hand, on the concentrate side, water and TMAH that have not been permeated are supplied to the filter 30B together with carbonates and dissolved resist that have not been able to permeate the NF membrane 40. The

  Also in the filter 30B, carbonate and dissolved resist are difficult to permeate the NF film 40, and thus are mainly supplied to the filter 30C via the line L16, while water and TMAH permeate the NF film 40 and pass through the line L30. To the adjustment tank 50.

  Similarly, the non-permeated liquid from the filter 30B is further filtered by the NF membranes 40 of the filter 30C and the filter 30D, and water and TMAH are supplied to the adjustment tank 50 through the line L30, while carbonic acid is added. A non-permeate containing salt, dissolved resist, water and TMAH is recycled to line L12 via line L20.

  Further, a part of the non-permeate liquid from the filter 30D is discharged to the drain tank 32 via the line L22, so that, for example, the carbonate concentration, resist concentration, etc. on the non-permeate side of the NF film 40 are not too high. Has been.

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

  According to such a system, the used resist developing solution in which carbonate and dissolved resist are accumulated by the developing operation in the resist developing device 12 is filtered through the NF film 40, so that the carbonate and dissolved resist are removed from the permeated solution. can do. Then, since this permeate returns to the resist developing device 12 via the adjustment tank 50 and is used as the resist developer, it is possible to suppress the deterioration of the developing performance of the resist developer accompanying an increase in carbonate or dissolved resist.

  Further, in the adjustment tank 50, the TMAH concentration in the filtrate from which carbonates and the like have been removed is measured by the conductivity meter 74. Since carbonate is partially ionized in the resist developer, the presence of a large amount of carbonate in the adjustment tank 50 hinders measurement of the TMAH concentration using a conductivity meter. However, according to the present invention, since the carbonate is removed in advance before the measurement of the conductivity, the TMAH concentration of the resist developer can be accurately measured. Therefore, the control device 80 can adjust and manage the TMAH concentration in the adjustment tank 50 with high accuracy, and more preferably develop in the resist developing device 12 that reuses the TMAH concentration.

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

  For example, although the plurality of filters 30A to 30D are connected in series in the above embodiment, a single filter can be operated, and a plurality of filters can be connected in parallel.

  Subsequently, the usefulness of the present invention will be shown based on examples. Here, as shown in FIG. 2, the resist developer used for development is supplied to one filtration device 30A via a line L100, and the permeate is discharged from the filtration device 30A via a line L104. In this case, a part of the non-permeated liquid is recycled to the line L100 via the line 102, and the rest of the non-permeated liquid is discharged via the line L103. Here, the flow rate of the resist developer supplied to the inlet of the line L100 is Qin, the flow rate of the resist developer discharged from the outlet of the line L104 is Qper, and the resist developer that is recycled to the line L100 via the line L102. Let Qr be the flow rate, and Qout be the flow rate of the resist developer discharged via the line L103.

  Here, the molecular weight cut off of the NF film 40 was 1000.

  In Example 1, a used resist developer obtained by developing a novolak resist using a resist developer containing 2.38% of TMAH was supplied as Qin to the entrance of the line L100. In Example 2, a used resist developer obtained by developing a novolak resist using a resist developer containing 2.379% TMAH was supplied as Qin to the entrance of the line L100. In Example 3, a used resist developer obtained by developing an acrylic resist using a resist developer containing 0.471% TMAH was supplied as Qin to the entrance of the line L100.

  The flow rate and concentration of each flow Qin, Qout, Qper, Qr after the filtration reaches a steady state are shown in the table of FIG. Here, the carbonate ion concentration was determined by ion chromatography, the deactivated TMAH concentration and the active TMAH concentration were determined by hydrochloric acid titration, and the dissolved resist concentration was determined by the dry weight method. It is thought that the formation of carbonate appears as an increase in carbonate ions and also as an increase in deactivated TMAH. In addition, it is thought that reaction with a resist other than formation of carbonate contributes to the deactivation of TMAH.

  As apparent from FIG. 3, the carbonate ion concentration and the deactivated TMAH concentration of the permeate Qper are considerably lower than the respective concentrations of the supply liquid Qin, while the carbonate ion concentration and the deactivated TMAH concentration of the non-permeate discharge liquid Qout are It had risen considerably. The dissolved resist also showed a tendency similar to the carbonate ion concentration. On the other hand, the active TMAH concentration did not change so much between Qin, Qper, and Qout.

FIG. 1 is a schematic flow diagram of a resist development system according to an embodiment of the present invention. FIG. 2 is a flowchart showing a filtration flow in the embodiment. FIG. 3 is a table showing each flow rate and concentration in Examples 1 to 3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 40 ... NF film | membrane, 74 ... Conductivity meter, 30A, 30B, 30C, 30D ... Filtration apparatus (filtration means), 14 ... Carbonate removal apparatus.

Claims (4)

  A method for removing carbonate in a resist developer, comprising a filtration step of filtering a resist developer containing tetramethylammonium hydroxide and carbonate through an NF film.   The method for removing carbonate in a resist developer according to claim 1, wherein the molecular weight cutoff of the NF film is 500 to 1500. Removing the carbonate in the resist developer using the method for removing carbonate in the resist developer according to claim 1 or 2,
A concentration measurement step of measuring the tetramethylammonium hydroxide concentration of the resist developer from which the carbonate has been removed, with a conductivity meter;
A resist developer concentration management method comprising: An apparatus for removing carbonate in a resist developer, comprising a filtering means for filtering a resist developer containing tetramethylammonium hydroxide and carbonate through an NF film.

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