JPH10123720A - Method for developing photosensitive resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain a constant concn. of a surfactant and to enable the succession of development by continuously or intermittently exchanging a part of a developer in a developer storage tank for an aq. surfactant soln. having practically the same concn. of the surfactant as the developer. SOLUTION: In order to suppress the reduction of the concn. of an alkali in a developer, the developer is continuously or intermittently replenished with a thick aq. alkali soln. In order to suppress the increase of the concn. of a photosensitive resin in the developer, part of a developer in a developer storage tank 2 is continuously or intermittently exchanged for an aq. surfactant soln. having a concn. of the alkali lower than the developer and having the practically same concn. of the surfactant as the developer. In this case, the consumption of the alkali is detected with an alkali sensor 9 and the required amt. of the thick aq. alkali soln. is fed from a thick aq. alkali soln. storage tank 3. The increase of the concn. of the photosensitive resin is detected with a photosensitive resin concn. sensor 9 and the aq. surfactant soln. is fed from an aq. surfactant soln. storage tank 4 so that a prescribed concn. or below is attained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for developing a photosensitive resin, and more particularly, to a method for continuously developing a photosensitive resin on an exposed liquid crystal substrate or semiconductor substrate.

[0002]

2. Description of the Related Art In the production of semiconductor substrates and liquid crystal substrates, an aqueous solution of tetramethylammonium hydroxide (hereinafter abbreviated as TMAH) or the like is used for developing a positive photosensitive resin on the exposed substrate. Is used. In many cases, this development is performed by a method in which a considerable amount of fresh developer is supplied to one substrate, and the developer is discarded after development, but in order to perform the development more efficiently. It is preferable to continuously develop a plurality of substrates in the photosensitive resin developing tank while circulating the developing liquid between the developing solution storage tank and the photosensitive resin developing tank.

In such a case, if the development is continued, a problem arises that the alkali in the circulating developer is consumed by the development and the alkali concentration decreases. In addition, the photosensitive resin gradually dissolves in the circulating developer, which causes a problem that the developing ability of the developer decreases. Therefore, in order to prevent a decrease in the developing ability due to the continuous development of the photosensitive resin, a circulating developer is supplied with a concentrated alkali aqueous solution in accordance with a decrease in the alkali concentration,
Alternatively, it is known that the developer is diluted with an aqueous alkali solution in accordance with an increase in the photosensitive resin concentration.

[0004]

In the development of such a photosensitive resin, it is known that if the photosensitive resin is dissolved even a little in a developing solution, a large amount of foaming occurs. This foaming causes poor development of the pattern on the substrate, lifting of the substrate in the photosensitive resin developing tank, supply and circulation of the developer,
Problems such as obstruction of the flow of the developing solution due to the intrusion of bubbles into the drainage pipe are seriously caused.

[0005] Under such circumstances, as a means for suppressing such foaming of the developer, a surfactant (antifoaming agent) is contained in the developer. At that time, if the concentration of the surfactant contained is too low, the above-described defoaming effect is lost, and if it is too high, the film thickness of the photosensitive resin in the unexposed portion is promoted during development, or conversely, it is exposed. It covers the photosensitive resin in some parts to suppress development and adversely affects development performance. Therefore, in order to exert the above-mentioned ability satisfactorily without adversely affecting the developing performance, the concentration of the surfactant must be controlled within a certain concentration range centering on the optimum value.

However, when the developer containing the surfactant is used to continuously develop the photosensitive resin, the circulating developer is treated to prevent the developing ability from decreasing.
In particular, when a dilution operation with an alkaline aqueous solution is performed, the concentration of the surfactant is greatly reduced, and there has been a problem that its ability cannot be maintained. In order to prevent this, a method of measuring the surfactant concentration of the circulating alkaline aqueous solution over time and adding a surfactant corresponding to a decrease in the surfactant concentration as a concentrated aqueous solution or the like can be considered. The measurement of the surfactant concentration and the fine adjustment of the surfactant concentration with a concentrated aqueous solution make the operation very complicated.

Further, it is conceivable that a surfactant having a known concentration is previously contained in a concentrated alkaline aqueous solution for adjusting the alkali concentration, and the concentration of the surfactant is simultaneously adjusted by adjusting the alkali concentration with the concentrated alkaline aqueous solution. However, in this case, since the concentrated alkaline aqueous solution is supplied in proportion to the alkali concentration of the developer, it is difficult to precisely adjust the concentration of the surfactant. In addition, when a surfactant is added to a concentrated alkaline aqueous solution, the solubility of the surfactant is reduced, the surfactant cannot be uniformly dissolved in the solution, and the surfactant is precipitated in micelles or as oil droplets. Come up.

In view of the above background, the present invention relates to a method for performing continuous development of a photosensitive resin using a developer comprising an aqueous alkali solution containing a surfactant. It is an object of the present invention to provide a simple method for preventing development and maintaining development while maintaining the surfactant at an acceptable constant concentration.

[0009]

Means for Solving the Problems In view of the above problems, the present inventors have intensively studied. As a result, by partially or intermittently exchanging a part of the developing solution in the developing solution reservoir with a surfactant aqueous solution having a surfactant concentration substantially equal to that of the developing solution, The inventors have found that the problem can be solved, and have completed the present invention.

That is, the present invention provides a method for exposing a photosensitive resin in a photosensitive resin developing tank while circulating a developing solution composed of an alkaline aqueous solution containing a surfactant between the developing solution storage tank and the photosensitive resin developing tank. In a method of continuously developing the photosensitive resin thus obtained, a concentrated alkaline aqueous solution is continuously or intermittently replenished to the developer in order to suppress a decrease in the alkali concentration of the developer, and In order to suppress the increase in the photosensitive resin concentration, a part of the developer in the developer storage tank,
A photosensitive resin having an alkali concentration not higher than the alkali concentration of the developer and a continuous or intermittent liquid exchange with a surfactant aqueous solution having a surfactant concentration substantially equal to that of the developer. Is a developing method.

In the present invention, a known developer comprising an aqueous alkali solution used for developing an alkali-soluble resist can be used without any limitation.
Specific alkalis include sodium hydroxide, potassium hydroxide, sodium hydrogen phosphate, which are inorganic alkalis,
Potassium carbonate, ammonia and the like, and organic alkalis include TMAH (tetraammonium hydroxide), trimethylmonoethanolammonium hydroxide, methylamine, ethylamine and the like. Further, these can be used in combination. In the present invention, it is preferable to use a TMAH aqueous solution.

Although the alkali concentration of the developer cannot be unconditionally determined by the type of alkali or the type of photosensitive resin to be developed, the allowable alkali concentration is in a narrow range in each case. This range is generally adopted from the range of 0.1 to 5.0% by weight. For example, when a TMAH aqueous solution is used for developing the positive photoresist, this range is usually 2.4% by weight ± 0.1%. %.

As the surfactant contained in the developer, known surfactants are used without any particular limitation. Specific examples include anionic surfactants, cationic surfactants, and nonionic surfactants, and among them, nonionic surfactants are preferably used.

The concentration of the surfactant contained in the developer is as follows:
Although it cannot be unconditionally determined by the type of surfactant or the type of photosensitive resin to be developed, the allowable concentration of surfactant in each case exists in a narrow range. This optimum concentration is generally in the range from 1 to 10000 ppm, preferably from 10 to 1000 ppm. At the optimum concentration of each surfactant in the above range, usually ± 20%, preferably ± 10%, and in some cases ± 5%
%, There is an allowable density that does not hinder development in practice.

According to the present invention, while a developer comprising an alkaline aqueous solution containing the above-mentioned surfactant is circulated between the developer storage tank and the photosensitive resin developer tank, the developer is exposed in the photosensitive resin developer tank. The developed photosensitive resin is continuously developed.
Here, the photosensitive resin is generally exposed to a desired pattern on a semiconductor substrate or a liquid crystal substrate. Specific examples of the resin include, but are not limited to, a positive resist, an azide-based negative resist, and a chemically amplified resist in which orthodiazonaphthoquinone and a novolak resin are mixed. Further, it is not limited to an exposure light source such as an i-line or an electron beam.

For the development of the photosensitive resin in the photosensitive resin developing tank, a known developing method can be adopted without limitation. Specific examples include a method in which an immersion method, a spray method, a shower method, and the like are performed in a batch system or a continuous system. The liquid volume of the developing solution storage tank is preferably 50 to 500 L, and the liquid volume of the photosensitive resin developing tank is preferably 50 to 500 L.
The amount of the alkaline developer circulating in the two tanks is not particularly limited, but is preferably 1 to 100 L / min. The liquid temperature is preferably 23 ± 5 ° C.

In the present invention, in carrying out continuous development of the photosensitive resin, first, a concentrated alkaline aqueous solution is continuously or intermittently added to the developer in order to suppress a decrease in the alkali concentration of the developer. Replenish. As a result, the alkali consumed by the development is supplemented, and the alkali concentration of the circulating developer is maintained at an allowable constant concentration.

Here, the alkali concentration of the concentrated alkaline aqueous solution is not particularly limited as long as it is higher than the alkali concentration of the developing solution, but is usually 15% by weight or more from the viewpoint of reducing the amount used. The amount is preferably not more than the solubility of the alkali used in water.

For replenishment of the concentrated alkaline aqueous solution, it is general that the alkali concentration of the circulating developer is measured with time, and a necessary amount is added according to the decrease. It is preferable that the alkali concentration is measured by a change in the conductivity of the circulating developer. The replenishment of the concentrated aqueous alkali solution performed in response thereto may be continuous, but is preferably performed intermittently at intervals in which the alkali concentration of the developer does not fall below the allowable concentration. The replenishment point of the concentrated alkaline aqueous solution is not particularly limited and may be in the middle of the circulation line. However, considering the ease of uniform mixing, it is preferably a developer storage tank.

Next, in the present invention, in addition to the above-described operation for preventing a decrease in alkali concentration, in order to suppress an increase in the photosensitive resin concentration of the developer, a part of the alkali developer in the developer storage tank is removed. The liquid is exchanged continuously or intermittently with an aqueous surfactant solution having an alkali concentration equal to or lower than the alkali concentration of the developer and having a surfactant concentration substantially equal to the surfactant concentration of the developer. As a result, even if the photosensitive resin is dissolved in the developer circulating during development, it is diluted by the aqueous solution of the surfactant, so that the concentration of the photosensitive resin can be prevented from exceeding the allowable concentration.

However, the present invention is most characterized in that the liquid used for the liquid exchange contains a surfactant at substantially the same concentration as the developer. Thereby, even if the developer is exchanged with a large number of liquids, the surfactant concentration does not substantially change to the developer. In addition, even if the concentration of the surfactant in the developing solution is reduced by the replenishment of the concentrated alkaline aqueous solution in the operation for preventing the alkali concentration from decreasing, the value is recovered.

Here, the surfactant may be used as it is or
Even if an attempt is made to adjust the concentration by replenishing the developer with a deficient amount as a concentrated aqueous solution, there is no means for simply detecting the surfactant concentration in the developer in real-time and in-line.
It is also conceivable to replenish the concentrated alkaline aqueous solution by adding a surfactant.However, in general, the surfactant is hardly compatible with the concentrated alkaline aqueous solution. It is substantially difficult to satisfy both the maintenance of the concentration and the maintenance of the surfactant concentration at the same time.

Here, the concentration of the surfactant in the aqueous surfactant solution is exactly the same as that of the developer used, and within the allowable concentration range of the surfactant required for the developer. In the present invention, it is regarded as substantially equal concentration. The general allowable concentration range for the optimum concentration of the surfactant in the developer is as described above. In the present invention, the surfactant concentration is most preferably the same as that of the circulating developer from the viewpoint that the concentration hardly varies. Further, by a replenishment operation of a concentrated alkaline aqueous solution for preventing a decrease in the alkali concentration,
In view of the fact that the concentration of the surfactant in the circulating developer slightly decreases, it is also a preferable embodiment to slightly increase the surfactant concentration of the aqueous surfactant solution from the same concentration.

The aqueous surfactant solution may contain an alkali at a concentration not higher than the alkali concentration of the developer. In particular, it is preferable to make the alkali concentration equal to the alkali concentration of the developer, because the alkali concentration does not change even when the developer is diluted with the aqueous surfactant solution. Further, even when the aqueous solution of the surfactant does not contain alkali or the concentration thereof is smaller than the alkali concentration of the developing solution, the thinner alkali is added to the concentrated alkali in accordance with the liquid exchange with the aqueous solution of the surfactant. By replenishing with an aqueous solution, development can be continued without any problem.

In the present invention, the above-mentioned aqueous surfactant solution may be adjusted to a desired concentration in a different place in advance, or it may be attached to a developing device on site to determine the concentrated aqueous surfactant solution to determine pure water and water. If necessary, a material diluted and adjusted with an alkali may be used.

The liquid exchange with the aqueous surfactant solution is generally carried out by measuring the concentration of the photosensitive resin in the circulating developer over time and following the rise. The measurement of the photosensitive resin concentration is preferably performed based on a change in transmittance of a circulating developer. The exchange of the developer in the developer storage tank in response thereto may be continuous, but is preferably performed intermittently at intervals where the photosensitive resin concentration does not exceed the allowable concentration.

The method of liquid exchange may be carried out by any method. Specifically, a surfactant aqueous solution in an amount that suppresses an increase in the concentration of the photosensitive resin is mixed with the developer in the developer storage tank. Then, the developing solution having the increased capacity may be replaced by overflowing or withdrawing the developing solution from the bottom of the tank. that time,
The alkaline developer storage tank is preferably sufficiently stirred by a stirrer or a tank circulation line. In addition,
The liquid exchange does not necessarily have to be in an equivalent relationship with the added surfactant aqueous solution.

The present invention will be described below in detail with reference to FIG. 1 which is a schematic view of a typical embodiment.

That is, in FIG. 1, 1 is a photosensitive resin developing tank, 2 is a developing solution storage tank, 3 is a concentrated alkaline aqueous solution storage tank, and 4 is a surfactant aqueous solution storage tank. The developing solution in the developing solution storage tank of No. 2 is sent to a developing solution shower nozzle of No. 7 through a filter of No. 6 and an alkali concentration sensor and a photosensitive resin concentration sensor of No. 9 by a developing solution circulation pump. A part of the developer in one photosensitive resin developing tank is 2
Is returned to the developer storage tank for circulation mixing purpose. When the developing substrate 8 is not brought into the photosensitive resin developing tank, the entire amount of the circulating liquid may be returned to the developing liquid storage tank. 7
The developer ejected from the shower is temporarily stored in the first photosensitive resin developing tank, and the overflow is returned to the second developing tank.

When the developing substrate 8 is developed, the photosensitive resin on the substrate is dissolved as a salt in the developing solution. At the same time, alkali is consumed.

The reduced amount of the consumed alkali is detected by the alkali sensor 9, and a required amount of the concentrated alkaline aqueous solution is supplied from the concentrated alkaline aqueous solution storage tank. When the amount of the photosensitive resin salt increases, a surfactant aqueous solution is supplied from the surfactant aqueous solution storage tank 4 so as to be detected by the photosensitive resin concentration sensor 9 and become a predetermined concentration or less. In this case, since the surfactant aqueous solution has substantially the same surfactant concentration as that of the circulating developer, the surfactant exchange of the developer does not greatly decrease by the liquid exchange.

[0032]

According to the present invention, in the case where the development of a photosensitive resin is carried out continuously using a developing solution comprising an aqueous alkali solution containing a surfactant, the concentration of the surfactant can be easily determined by a simple method. Is maintained, and development can be continued while maintaining the surfactant at an acceptable constant concentration. Further, the alkali concentration and the photosensitive resin concentration are also maintained at constant concentrations. Therefore, the present invention is industrially extremely useful as a practical photosensitive resin developing method.

[0033]

EXAMPLES The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited to these examples.

Example 1 Using the developing device shown in FIG. 1, continuous development of the photosensitive resin was performed. The capacity of one photosensitive resin developing tank is 300
cc, the capacity of the developing solution storage tank was 900 cc.
Using a 4 inch wafer as a development substrate, and a positive photoresist (naphthoquinone diazizo-novolak) on it
Was applied, and a 10 μm line-and-space test pattern was exposed.

The developer and the aqueous solution of the surfactant may be a nonionic surfactant (polyoxyethylene oleyl ether;
A 2.37% by weight aqueous TMAH solution containing 300 ppm) was used. As the concentrated alkaline aqueous solution, a 20% by weight TMAH aqueous solution was used.

During the continuous development of the developing substrate, before the TMAH concentration of the developing solution reaches 2.365% by weight, a concentrated alkaline aqueous solution having a concentration of 2.65% is used as the developing solution.
It was replenished intermittently so as not to exceed 375% by weight. Before the absorbance of the developing solution became smaller than 0.1, the aqueous solution of the surfactant was intermittently mixed with the developing solution and the solution was exchanged by overflow. In the above liquid exchange, the absorbance of the developer was reduced to 0.06.

After developing 50 wafers, the line width of the test pattern was measured at any five points on each wafer. The average line width of the first sheet was 10.1 μm, and the average line width of the 50th sheet was 10.3 μm. Also, no bubbles were observed on the liquid surfaces of the photosensitive resin developing tank and the developing solution storage tank.

Comparative Example 1 In Example 1, as a developer and an aqueous solution of a surfactant used, 2.37% by weight containing no surfactant was used.
The experiment was carried out by changing to the TMAH aqueous solution.

The average line width of the first sheet was 10.0 μm, and the average line width of the 50th sheet was 10.5 μm.

However, when the fourth sheet was processed, foaming of the photosensitive resin developing tank and the developing solution storage tank became severe, and
Bubbles spilled out of each tank from the first sheet. Also,
SEM is performed on the arbitrary five wafers after the sixth wafer.
As a result of observing the surface by (scanning electron microscope), a scum-like development defect was observed in a portion of each wafer where the development of the resist was removed.

Comparative Example 2 In Example 1, as a developer and an aqueous solution of a surfactant used, 2.37% by weight containing no surfactant was used.
The experiment was carried out using a TMAH aqueous solution as described above, and a concentrated alkaline aqueous solution containing a surfactant further containing 8.4 times the surfactant concentration of the developer used in Example 1. Was.

The average line width of the first sheet was 10.1 μm, and the average line width of the 50th sheet was 8.9 μm.

As a result of measuring the surfactant concentration of the developer in the developing tanks of Example 1 and Comparative Example 2 by liquid chromatography,
The relative peak intensity of Comparative Example 2 was slightly less than 10 times that of Examples. This indicates that the concentrated developer supplied in accordance with the consumption of alkali caused an excessive supply of the surfactant.

However, no bubbles were observed on the liquid surfaces of the developing tank and the developing solution storage tank.

Example 2 In Example 1, an aqueous solution containing no TMAH was used as the surfactant aqueous solution, and the aqueous solution was concentrated so as to compensate for the decrease in the alkali concentration of the developer together with the liquid exchange with the surfactant aqueous solution. The experiment was performed by supplying an aqueous alkali solution.

The average line width of the first sheet was 10.0 μm, and the average line width of the 50th sheet was 10.2 μm. However, as for the TMAH concentration in the developer, the average line width in Example 1 tended to increase in direct proportion to the increase in the number of processed sheets. The width varied slightly. The maximum value of the average line width is 10.8 μm, and the minimum value is 9.8.
μm.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a representative embodiment of the present invention.

[Explanation of symbols]

Reference Signs List 1; photosensitive resin developer tank 2; developer storage tank 3; concentrated alkaline aqueous solution storage tank 4; surfactant aqueous solution storage tank 5; developer circulation pump 6; filter 7; developer solution nozzle 8; development substrate 9; Concentration sensor and photosensitive resin concentration sensor 10; Stirrer for developer storage tank 11; Nitrogen inlet tube for sealing

Claims (1)

[Claims] A photosensitive resin exposed in a photosensitive resin developing tank while circulating a developing solution composed of an alkaline aqueous solution containing a surfactant between the developing solution storage tank and the photosensitive resin developing tank. In a method of continuously developing a resin, a concentrated alkaline aqueous solution is continuously or intermittently replenished with a developer in order to suppress a decrease in the alkali concentration of the developer, and the photosensitive resin concentration of the developer is reduced. In order to suppress the rise of
A part of the developing solution in the developing solution storage tank, the alkali concentration is equal to or less than the alkali concentration of the developing solution, and the surfactant concentration is continuous or continuous with a surfactant aqueous solution having substantially the same concentration as the developing solution. A method for developing a photosensitive resin, comprising intermittent liquid exchange.