KR101446619B1 - Method for regulating concentration of developing solution, apparatus for preparing the developing solution, and developing solution - Google Patents

Abstract

There is provided a method and apparatus for controlling the concentration of a developer which adjusts the alkali concentration of an alkaline developer used in a development process of a photoresist to a high quality development process.

The concentration of the developing solution is measured by measuring the alkali concentration of the developing solution and the concentration of the carbonate in the developing solution and determining the relationship between the alkali concentration and the carbonate concentration that can exert the solubility so that the CD value obtained by the developing treatment is a constant value Basically adjust the alkali concentration. The apparatus for producing a developer includes a supply tank for supplying the developer to the developing process, a collecting line for receiving the spent developer, a stock solution supply line for supplying the stock developer to the production tank, a concentration of the developer in the developer, And a control device for controlling supply of the developer liquid based on a specific relationship.

Developer, alkaline concentration, carbonate concentration, CD value,

Description

TECHNICAL FIELD The present invention relates to a method and apparatus for controlling the concentration of a developer, a method for regulating the concentration of the developer,

The present invention relates to a method for controlling the concentration of a developer, a manufacturing apparatus and a developer, and more particularly, to a method for adjusting the alkaline concentration of an alkaline developer used for developing a photoresist in a manufacturing process of a liquid crystal substrate, A method of adjusting the concentration of a developing solution which can maintain a developing speed and which is adjusted to an appropriate concentration so as to enable a higher quality developing treatment, an apparatus for producing a developing solution suitable for carrying out the concentration adjusting method, Gt;

In the manufacturing process of the photoresist in the manufacturing process of the liquid crystal substrate, the printed substrate, and the like, an alkali aqueous solution containing tetramethylammonium hydroxide (TMAH) as a main component is used as the developer. Such an alkaline developing solution is now used in large quantities due to the enlargement of the substrate size and the progress of the process, and is recovered from the viewpoint of cost reduction and regenerated in the developing process. However, as the use is repeated, the alkali concentration is lowered due to the reaction with acid in the resist or the reaction with oxygen or carbon dioxide gas in the air during the process stop, whereby the dimensional accuracy of the resist pattern in the developing process, Since the film thickness accuracy is lowered, it is important to keep the alkali concentration constant.

Regarding the concentration control of the developer, for example, an apparatus for managing an alkaline developer used for development of a photoresist is provided, in which a developer is circulated and supplied to a developing apparatus, and both the alkaline concentration of the developer and the dissolved resin concentration in the developer And the developer is prevented from deteriorating, and a "developer management device" In such a developer control apparatus, the concentration of the dissolved resin in the developer is detected by a spectrophotometer, the alkali concentration of the developer is detected by a conductivity meter, and the concentration of the alkali in the developer, the concentration of the dissolved resin, The developing solution in the apparatus is discharged, and the developer solution and the pure water are supplied, or the newly produced developer solution is supplied.

Patent Document 1: Japanese Patent No. 2561578

DISCLOSURE OF INVENTION

Problems to be solved by the invention

However, in the production of a substrate, even when the alkali concentration of the developer or the concentration of the dissolved resin in the developer is constantly controlled, when the developing process and the etching process are performed, the line width of a pattern such as a circuit, I see a fluctuating phenomenon. Actually, when the developer is recycled, the line width (CD width) of the photoresist pattern such as a circuit formed on the substrate by development processing tends to deviate gradually from the reference value (design value). That is, the developing rate, in other words, the dissolution rate to the photoresist varies during the repetition of the processing in the developing process, and the dimensional accuracy of the resulting resist pattern gradually decreases. As a result, the line width of the pattern formed on the substrate is affected by the etching. Therefore, in the supply management of the developer, an improved management method which does not cause variation in the developing speed is desired.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described circumstances, and its object is to provide a method for controlling the concentration of alkali in an alkaline developing solution used for developing a photoresist in a manufacturing process of a liquid crystal substrate, And a method of controlling the concentration of a developer capable of performing a high-quality developing process. Another object of the present invention is to provide an apparatus for producing a developer capable of producing a developer capable of performing a high-quality development process by using an alkaline spent developer recovered from the development process of the photoresist. It is another object of the present invention to provide a developer capable of performing high-quality development processing as an alkaline developer which can be obtained by using the concentration control method and the production apparatus and effectively using the spent developer.

Means for solving the problem

In order to solve the above problems, the inventors of the present invention have made various investigations and found that although the alkali concentration is maintained at the reference concentration and the dissolved resin concentration is managed in the developer, And the dissolution rate of the developer was lowered. As a result of studying the relationship between the CD value and the carbonate concentration in the developing solution as to the influence of the carbonate on the solubility of the developing solution, it was found that the solubility of the developer due to the increase of the carbonate concentration It is found that it is lowered to a certain tendency. It has been found that the developing ability of the developer with respect to the photoresist can be kept constant by adjusting the concentration so that the alkali concentration is increased on the basis of the specific relationship with the increase of the carbonate concentration in the developer.

That is, the first aspect of the present invention is a method for controlling the concentration of alkali in an alkaline developing solution used for developing a photoresist, comprising the steps of measuring the alkali concentration of the developing solution and the concentration of the carbonate in the developing solution, And the alkali concentration is adjusted on the basis of a previously prepared relationship between the alkali concentration and the carbonate concentration capable of exhibiting solubility so that the CD value becomes a constant value.

A second aspect of the present invention is an apparatus for producing an alkaline developer used for developing a photoresist, comprising: a tank for producing a developer of a predetermined concentration; a supply line for supplying the produced developer to a developing process; A recovery line for receiving the finished developer in the production tank, a raw solution supply line for supplying a new developer solution having a higher concentration of alkali than the reference concentration to the production tank, a concentration meter for detecting the alkali concentration of the developer in the production tank and the carbonate concentration in the developer, And a control device for controlling the supply of the developer stock solution from the stock solution supply line on the basis of the concentration detected by the concentration meter, wherein the control device controls the concentration of the developer in the developer, So that the CD values that can be obtained by processing are constant values And has a function of regulating the alkali concentration by controlling the supply of the developer stock solution on the basis of the previously prepared relationship between the alkali concentration and the carbonate concentration capable of exhibiting solubility.

Further, in the present invention, in order to more precisely control the alkali concentration, the alkali concentration may be adjusted in consideration of the concentration of the carbonate in the developer and the concentration of the dissolved resin. That is, a third aspect of the present invention is a method for controlling the concentration of alkali in an alkaline developing solution used for developing a photoresist, comprising the steps of measuring the alkali concentration of the developing solution, the carbonate concentration in the developing solution and the dissolved resin concentration, Wherein the alkali concentration is adjusted on the basis of a previously prepared relationship between an alkali concentration, a carbonate concentration and a dissolved resin concentration that can exhibit solubility so that the CD value obtainable by the above method is a constant value exist.

A fourth aspect of the present invention is an apparatus for producing an alkaline developer for use in developing a photoresist, comprising: a tank for producing a developer of a predetermined concentration; a supply line for supplying the produced developer to a developing process; A recovery line for receiving the finished developing solution into the production tank, a raw solution supply line for supplying a new developer solution having an alkali concentration higher than the reference concentration to the manufacturing tank, an alkali concentration of the developing solution in the manufacturing tank, a carbonate concentration in the developing solution, And a control device for controlling the supply of the developer stock solution from the stock solution supply line on the basis of the concentration detected by the concentration meter and the concentration of the developing solution measured by the concentration meter, Carbonate concentration and dissolved resin concentration, obtained by development processing And a function of controlling the alkali concentration by controlling the supply of the developer stock solution on the basis of the previously prepared relationship between the alkali concentration, the carbonate concentration and the dissolved resin concentration, which can exhibit solubility so that the value of the CD present therein is a constant value In the developing solution.

Effects of the Invention

According to the present invention, in order to adjust the alkali concentration of the developer based on a specific relationship with the increase of the carbonate concentration in the developer, and to keep the solubility of the developer in the photoresist constant, The development speed can be maintained, and high-quality development processing becomes possible. Further, according to the carbonate concentration and the dissolved resin concentration in the developing solution, the alkali concentration of the developing solution is adjusted on the basis of a specific relationship, whereby higher quality developing treatment becomes possible.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a graph showing the relationship between the carbonate concentration and the alkali concentration to the reference concentration, and the relationship between the carbonate concentration and the alkali concentration capable of exhibiting the predetermined solubility.

Fig. 2 is a graph showing the influence of the carbonate concentration in the developer relative to the line width (CD value) of the photoresist pattern obtained by the development processing.

3 is a graph showing the influence of the dissolved resin concentration in the developer relative to the line width (CD value) of the photoresist pattern obtained by the development processing.

4 is a flow chart showing the main components of the apparatus for producing a developer according to the present invention.

Explanation of symbols

1: Manufacturing tank

2: supply line

21: Pump

3: recovery line

4:

41: Pump

5: Densitometer

6: Liquid supply line

61: Flow control valve

7: Diluted water supply line

71: Flow control valve

8: New supply line

81: Flow control valve

9: developing device

A:

B: Diluent feeder

C: New fluid supply mechanism

Carrying out the invention  Best form for

A method for adjusting the concentration of the developer according to the present invention and an apparatus for producing a developer will be described with reference to the drawings.

The method for adjusting the concentration of the developer according to the present invention (hereinafter abbreviated as "concentration control method") is an alkaline developer used for developing the photoresist in a developing process including a developing apparatus such as a spin developer apparatus, (Hereinafter abbreviated as "developing solution"), and the apparatus for producing a developing solution according to the present invention (hereinafter referred to as "manufacturing apparatus") is a manufacturing apparatus for producing the developing solution , The present invention is particularly suitable for reusing a used developer recovered from a developing process of a photoresist in a manufacturing process of a liquid crystal substrate, a printed substrate, etc., as a developing process.

In the present invention, as the alkali component of the developer, an inorganic alkali aqueous solution consisting of an inorganic alkali such as potassium hydroxide, sodium hydroxide, sodium phosphate, sodium silicate, etc., or an inorganic alkali aqueous solution containing tetramethylammonium hydroxide (TMAH), trimethylmonoethanolammonium And an aqueous solution of an organic alkali such as hydroxide (corin). When TMAH is used as the developer, the TMAH concentration (alkali concentration) is set to 2.380 wt%, for example. The developing solution may contain a conventional known additive such as a nonionic surfactant or a fluorinated surfactant.

In the present invention, the term "CD value" refers to the line width of a photoresist pattern that can be obtained on a substrate by development processing. The "reference concentration" of alkali to be described later refers to the concentration of alkali (initial alkali concentration) at which the following CD value is obtained. The above-mentioned CD value is a CD value at the time when the developing process is performed for a predetermined period of time and is the original CD value serving as an evaluation reference before the value changes. The alkali to be used as such a reference may be alkali alone or may contain the above additives, and it is preferable to add the difference in solubility of the additive in terms of the reference concentration of the alkali in the case of using the actual solution containing the additive.

First, a manufacturing apparatus suitable for carrying out the concentration control method of the present invention will be described. As shown in Fig. 4, as a production apparatus for producing a developing solution used in developing treatment, the developer thus recovered from the developing process is used to produce the developing solution. Such a production apparatus includes a production tank 1 for producing a developer of a predetermined concentration, a supply line 2 for supplying the produced developer to a developing process (hereinafter referred to as "developing apparatus") such as the developing apparatus 9, A raw material supply line 6 for supplying a new developer liquid having an alkali concentration higher than the reference concentration to the production tank 1, a raw material supply line 6 for supplying the raw developer to the production tank 1, A concentration meter 5 for detecting the alkali concentration of the developer and the carbonate concentration in the developer, and a control device (not shown) for controlling the supply of the developer stock solution from the stock solution supply line 6 on the basis of the concentration detected by the concentration meter .

The manufacturing tank 1 is a supply tank for regulating the concentration of the developer to a predetermined target value and supplying the developer with the concentration adjusted to the developing apparatus 9 as required, and has a corrosion resistance of about 100 to 2000 liters It is constituted by one container. In the manufacturing tank 1, a circulation flow passage 4 in which a pump 41 is opened is provided as a means for stirring the developing solution in order to maintain the developer solution in a uniform concentration. The stirring means by circulation as described above is less likely to generate particles as compared with a stirring apparatus such as a screw provided in the tank and can reduce the contamination of the developer.

The recovered spent developer is adjusted to a constant temperature in the developing device 9, and the developer in the manufacturing tank 1 is maintained at a substantially constant temperature. However, in order to more accurately measure the concentration of the developer by the concentration meter 5 described later, it is preferable to maintain the temperature of the developer in the production tank 1 at a precise temperature (for example, 25 DEG C). In a preferred embodiment, temperature control means (not shown) including a heater and a cooler is provided in the manufacturing tank 1 or the circulating flow path 4.

The supply line 2 is constituted by a flow path from the manufacturing tank 1 to the developing device 9 and a pump 21 opened in the flow path and is used to transfer the produced developer in the manufacturing tank 1 to the developing device 9 . The recovery line 3 is constituted by a flow path from the discharge port (drain of the chamber) of the used developer of the developing apparatus 9 to the production tank 1 and is connected to the pump (Not shown) is used, and the used developing solution is recovered in the manufacturing tank 1. [ Although not shown, the recovery line 3 may be provided with a buffer tank for temporarily storing the used developing solution. In order to adjust the temperature of the used developing solution to a temperature equivalent to that of the developing solution in the manufacturing tank 1, Or the like may be provided.

The undiluted solution supply line 6 is composed of a flow path from the undiluted solution supply mechanism A (not shown) to the production tank 1 and a flow control valve 61 opened to the flow path, When the concentration is lowered, a developer solution having a concentration higher than the reference concentration, for example, a developer solution having a concentration of 20-25% by weight in the case of TMAH, As shown in Fig. The undiluted solution supply mechanism A is provided with an undiluted solution reservoir of about 500 to 3,000 liters for containing developer solution of high concentration in advance and a pump for delivering the undiluted developer solution from the undiluted solution reservoir of the flow passage to the production tank 1 .

Further, in the production apparatus of the present invention, in order to lower the concentration of the developer when the alkali concentration of the developer in the production tank (1) becomes higher than the target concentration, a diluting water supply line (Not shown). The dilution water supply line 7 is composed of a flow path from the diluting water supply mechanism B (not shown) to the production tank 1 and a flow rate regulating valve 71 that is opened in the flow path, And ultrapure water is supplied to the manufacturing tank 1 under the control of the flow rate control valve 71. As the diluting water supply mechanism (B), a pure water producing apparatus including a storage tank and a liquid delivery pump is usually used.

Further, in the production apparatus of the present invention, in the case where the amount of the developer in the production tank (1) is reduced to a certain amount, a fresh liquid supply line (8) for supplying a new developer of the reference concentration to the production tank Respectively. The fresh liquid feed line 8 is constituted by a flow path from the fresh liquid feed mechanism C (not shown) to the production tank 1 and a flow rate regulating valve 81 opened in the flow path, (For example, TMAH having a concentration of 2.38 wt%) is supplied to the production tank 1 under the control of the valve 81. [ The fresh liquid supply mechanism C is mainly composed of a fresh liquid reservoir of about 500 to 3,000 liters of internal capacity for accommodating a new developing liquid in advance and a pump for feeding the developing liquid from the fresh liquid reservoir tank to the flow path leading to the manufacturing tank 1 .

In the production apparatus of the present invention, the concentration meter (5) is usually opened in the above-described circulation channel (4) in order to more accurately measure the alkali concentration of the developer in the production tank (1) and the carbonate concentration in the developer. As the concentration meter (5), a specific concentration meter is used in order to measure the concentration with high accuracy without being influenced by the fluctuation of the dissolved resin concentration in the developer. Specifically, as the concentration meter 5, the temperature of the developer, the ultrasonic propagation speed and the electronic conductivity are measured, and based on the relationship (matrix) between the ultrasonic wave propagation speed and the electronic conductivity at a predetermined temperature, A multi-component concentration meter capable of detecting the alkali concentration of the developer and the carbonate concentration in the developer is used.

The multicomponent densitometer is a densitometer capable of simultaneously measuring the concentration of two components of an alkali and a carbonate by measuring an ultrasonic wave propagation velocity and an electronic conductivity in a solution at a constant temperature. That is, the multicomponent densitometer is based on the principle that the ultrasonic wave propagation velocity and the electron conductivity in the liquid are uniquely specified according to the concentration of each component when the solution temperature is constant. For example, when two components are measured, An ultrasonic wave transmitter, an electronic conductivity converter, an electronic conductivity transmitter, and a microprocessor for performing a predetermined operation.

By using the relationship between the ultrasonic wave propagation velocity and the electronic conductivity measured beforehand under a predetermined temperature condition for each combination of the alkali concentration and the carbonate concentration in the case of applying the above concentration measurement of the developer in the multicomponent densitometer as a matrix, That is, by writing in the microprocessor, the alkali concentration and the carbonate concentration can be accurately estimated from the measured values based on the above matrix. Examples of the multi-component densitometer as described above include a liquid multi-component densitometer manufactured by Fuji Kogyo Co., Ltd. In addition to the above-mentioned multi-component densitometer, a densitometer for measuring the refractive index of the fluid or a near-external densitometer for measuring the wavelength of the near-infrared region may be used as the concentration meter for measuring the alkali concentration. A densitometer using neutralization titration or the like can be used.

In the production apparatus of the present invention, a control device (not shown) for controlling the feeding of the developer solution, the feeding of the diluted water, and the feeding of a new developer based on the measurement of the concentration meter 5, Respectively. Such a control device includes an input device for digitally converting signals of the respective measuring instruments, an arithmetic processing device such as a program controller and a computer, and an output device for analog-converting the control signal from the arithmetic processing device.

The above control device is configured to control the supply of the developer stock solution from the stock solution supply line 6 on the basis of the concentration detected by the concentration meter 5. In other words, the control device controls the relationship between the alkali concentration of the developer measured by the densitometer 5 and the carbonate concentration in the developer, the relationship between the previously prepared carbonate concentration and the deficiency of the alkali concentration with respect to the reference concentration, Has a function of controlling the alkaline concentration by controlling the supply of the developer stock solution on the basis of the previously prepared relationship between the alkali concentration and the carbonate concentration capable of exhibiting solubility so that the value becomes a constant value. As a result, the used developing solution can be recovered from the developing device 9 in the production apparatus of the present invention, and a developer having an appropriate alkali concentration can be produced in the production tank 1.

The control device is also configured to control supply of diluting water from the diluting water supply line 7 and supply of new developing solution from the fresh solution supply line 8 together with supply of the developer solution. As a result, the liquid amount of the developer in the production tank (1) can be constantly controlled in the production apparatus of the present invention.

Further, in the manufacturing apparatus of the present invention, the inside of the system is sealed by an inert gas such as nitrogen in order to prevent contact between the developer and the developer solution. Further, in the manufacturing apparatus of the present invention, a mechanism for discharging excess spent developer to the outside of the system is provided at a suitable position when supplying the developer liquid to keep the liquid amount in the system constant. Although not shown, for example, in the manufacturing tank 1, a drain passage or an overflow device including a control valve is installed.

Next, the concentration control method of the present invention together with the function of the above production apparatus will be described. In the concentration control method of the present invention, in the production of a developing solution using the above-described manufacturing apparatus, the used developer discharged from the developing apparatus 9 is recovered to the manufacturing tank 1 by the recovery line 3 The developing solution in the manufacturing tank 1 (developing solution containing the used developing solution) is circulated to the circulating flow path 4, and while stirring and mixing, the developing solution is maintained at a predetermined temperature by the temperature adjusting means, The concentration of the carbonate in the developing solution is measured by a concentration meter (5). As the concentration meter 5, the aforementioned multi-component concentration meter is used.

After the alkali concentration of the developing solution in the manufacturing tank 1 and the carbonate concentration in the developing solution are measured, the control device controls the flow rate regulating valve 61 of the undiluted solution supplying line 6 and the alkali of the developing solution in the manufacturing tank 1 Adjust the concentration to an appropriate concentration. In this case, in the present invention, based on the previously prepared relationship between the alkali concentration and the carbonate concentration capable of exerting the solubility so that the previously prepared carbonate concentration and the alkali concentration are insufficient for the reference concentration, that is, the CD value becomes a constant value So that the alkali concentration is adjusted to a value equal to or greater than the reference concentration corresponding to the measured value of the carbonate concentration. Thus, the solubility of the developer in the photoresist can be kept constant. The above idea of the present invention will be further described in detail as follows.

When the developing solution is recycled for the developing process, carbonic acid gas is sucked in the air to generate carbonate in the developing solution. This carbonate counteracts the solubility of the developing solution on the photoresist, Degrade precision. As a result, the line width of the circuit pattern formed on the substrate is different from the design width. Therefore, when the alkali concentration of the developer and the development time in the development process are set to be constant, the CD value is highly correlated with the carbonate concentration in the developer used.

The influence of the carbonate concentration in the developer relative to the CD value is as shown in Fig. FIG. 2 is a graph showing the relationship between the concentration of alkali (TMAH) and the concentration of the alkali developing agent (TMAH) in the range of from 3 to 5 kinds of concentrations ranging from 2.20 to 3.27% (CD value of 2.77 to 5.0) in the case of using a freshly prepared developer having a carbonate concentration of 0 ppm (five kinds having different alkali concentrations) as shown in Fig. 2, 5.16 占 퐉, a developing solution having a CD value of 3.70 to 5.05 占 퐉 and a carbonate concentration of 1000 ppm (four kinds of different alkali concentrations) was used in the case of using a developer having a carbonate concentration of 525 ppm (four kinds of different alkali concentrations) The CD value is 3.59 to 4.30 탆. In other words, the relationship shown in Fig. 2 shows that the solubility of the developer in the photoresist is lowered to a constant tendency with the correspondence of the carbonate concentration in the developer, and the CD value increases in a constant relation.

Therefore, when the CD value is to be kept constant in the developing process, it is necessary to increase the alkali concentration in accordance with the carbonate concentration. For example, when the CD value is set to 4.00 mu m, the alkaline concentration (TMAH concentration) is adjusted to 2.38 wt% (reference concentration) when a freshly prepared developer having a carbonate concentration of 0 ppm is used, The alkali concentration (TMAH concentration) should be adjusted to 2.50% by weight in the case of use, and the alkaline concentration (TMAH concentration) should be adjusted to 2.71% by weight in the case of using a developer having a carbonate concentration of 1000 ppm.

From the above relationship, as for the alkali concentration required in the developer, as a relation between the carbonate concentration and the required correction amount of the alkali concentration (the relation with the deficit with respect to the reference concentration of the alkali concentration) when the CD value is kept constant, As shown in Fig. The relation between the carbonate concentration and the alkali concentration with respect to the reference concentration is a relationship derived in advance from the relationship between the alkali concentration and the carbonate concentration in the case of carrying out a constant development process (treatment of obtaining a constant CD value) Means a relationship with a deficiency in the carbonate concentration and the alkali concentration of the reference (the concentration of the developer when a newly produced developer containing no carbonate is used). In the graph of Fig. 1, the numerical value in parentheses of the TMAH concentration (alkali concentration) on the ordinate shows the concentration deficiency with respect to the reference concentration (2.38 wt%).

The present invention focuses on the relationship between the alkali concentration and the carbonate concentration in the developer when the CD value is kept constant as described above, and corrects the reference alkali concentration according to the carbonate concentration. In the case of using TMAH, the correction amount (the shortage of the carbonate concentration and the alkali concentration with respect to the reference concentration) shown in Fig. 1 can be expressed by the following approximate expression:

In formula (I)

y = 8 x 10 ^-8 x ² + 2 x 10 ^-4 x (I)

Where x is the carbonate concentration (ppm) and y is the TMAH concentration (wt%).

In order to confirm the relationship shown in Fig. 2 and to find the relationship between the approximate expression and Fig. 1, a plurality of developing solutions (for example, a practically used TMAH aqueous solution) and a carbonate A plurality of kinds of developing solutions as samples having different alkali concentrations are prepared and prescribed development processing is carried out in which the temperature and developing time are kept constant for each developing solution and the CD value of each obtained resist pattern is measured. At this time, with respect to the developing solution of each alkali concentration including the carbonate, the carbonate concentration is adjusted to be, for example, 100 ppm, 325 ppm, 500 ppm, 1000 ppm, 1500 ppm, and 2000 ppm by adding a calculated amount of dry ice while confirming the carbonate concentration Several species are produced. Then, a relational expression is estimated from the obtained result by statistical processing.

In the present invention, based on the previously prepared relationship between the alkali concentration and the carbonate concentration capable of exhibiting the solubility in which the CD value becomes constant, based on the above formula (1) (the relationship of the graph shown in FIG. 1) , And the alkali concentration is adjusted according to the carbonate concentration in the developer. In other words, the alkali concentration is adjusted to a value equal to or higher than the reference concentration according to the measured value of the carbonate concentration. As a result, the solubility of the developer can be kept constant, the dimensional accuracy of the resist pattern can be increased, and the CD value can be controlled at a constant level. When the carbonate concentration in the developing solution is 0 ppm, the alkali concentration is set to the reference concentration.

In practicing the present invention in a production apparatus, etc., it is necessary to determine the actual alkali concentration in accordance with the carbonate concentration so as to obtain a constant CD value in the control of the concentration of the developer. In this case, the relation between the previously prepared carbonate concentration and the alkali concentration capable of exhibiting the predetermined solubility, that is, the relationship between the alkali concentration and the carbonate concentration capable of exhibiting solubility so that the CD value becomes a constant value The relationship between the above-described deficiency and the alkali concentration), and the alkali concentration is adjusted. The above relationship is shown in the graph of Fig. 1 as the relationship between the carbonate concentration on the abscissa and the TMAH concentration on the ordinate. Therefore, in the case of using TMAH, the relationship (the relationship between the carbonate concentration and the alkali concentration capable of exhibiting the predetermined solubility) can be expressed by the following approximate expression:

expression( II )

y = 8 x 10 ^-8 x ² + 2 x 10 ^-4 x + 2.38 (II)

Where x is the carbonate concentration (ppm) and y is the TMAH concentration (wt%).

In the production apparatus of the present invention, the control apparatus includes an algorithm for concentration measurement and control calculation. The concentration adjustment in the production tank (1) is carried out by adjusting the concentration of alkali in the developer measured by the concentration meter (5) The flow rate control valve 61 of the undiluted solution supply line 6 is controlled in accordance with the above formula (II) and the alkaline concentration is adjusted to a predetermined target value by adding a developer solution suited to the deficiency of the alkali concentration. In the case where the alkali concentration is too high in view of the above relationship (relation of the formula (II)), pure water for dilution is supplied to the production tank 1 through the dilution water supply line 7.

When the amount of the developer in the manufacturing tank 1 is reduced by discharging a part of the recovered spent developing solution, the developer stock solution and pure water are supplied to the manufacturing tank 1 through the stock solution supply line 6 and the diluting water supply line 7 And the alkaline concentration is adjusted by the above operation to adjust the liquid amount of the production tank 1 to a certain range. Or a new developer is supplied to the production tank 1 through the fresh solution supply line 8 to adjust the solution amount.

The supply control of the developer stock solution, the supply control of the diluted water, and the supply control of the fresh developer solution are controlled by the supply amount of the developer stock solution from the stock solution supply mechanism A, the supply amount of pure water from the dilution water supply mechanism B, By cascade-controlling the supply amount of the developing solution. In these controls, a so-called asymptotic method disclosed in, for example, Japanese Patent No. 3741811, which is described in "Dilution method and diluting device for alkaline developing stock solution"

Concretely, for example, the adjustment of the alkali concentration in the production tank 1 using the above-mentioned asymptotic method is carried out by adding a high concentration developer stock solution (or diluted water) to the developer in the production tank 1 whose alkali concentration has decreased (or the alkali concentration has become high) ) Is added to the concentration of the developing solution to measure the concentration of the developing solution by the concentration meter 5 in adjusting the concentration to a predetermined concentration, and the difference between the concentration measured in the concentration measuring step and the target concentration (concentration obtained from the formula (II) The amount of the developer stock solution (or the amount of the diluting water added) is calculated, and a production step of supplying an amount corresponding to 85 to 99%, preferably 92 to 98% of the calculated deficiency amount (or addition amount) . The manufacturing process is repeated from the concentration measurement process until the measured concentration reaches a value within a threshold value of a predetermined target concentration. As a result, the alkali concentration in the developer in the production tank (1) can be controlled with higher precision.

As described above, the alkali concentration is adjusted to a value equal to or higher than the reference concentration in accordance with the measured value of the carbonate concentration, based on the relationship between the carbonate concentration and the alkali concentration previously prepared in the present invention. That is, the alkali concentration is adjusted on the basis of the previously prepared relationship between the alkali concentration and the carbonate concentration capable of exhibiting solubility so that the CD value becomes a constant value. Thereby keeping the solubility of the developer in the photoresist constant. Therefore, according to the present invention, it is possible to maintain a constant development speed with respect to the photoresist in the development process, and to further improve the dimensional accuracy and the film thickness accuracy of the resist pattern formed in the development process, .

Further, in the present invention, in order to adjust the alkali concentration more precisely, the alkali concentration may be adjusted according to the concentration of the dissolved resin together with the carbonate concentration in the developer. As described above, when the developer is recycled and supplied, carbonate is generated in the developer, and the photoresist is dissolved in the developer by the developing process, and the dissolution resin tends to slightly decrease the solubility of the developer. Therefore, in adjusting the alkali concentration as described above, it is preferable to correct it according to the concentration of the dissolved resin in the developer.

The influence of the dissolved resin concentration in the developer relative to the CD value is as shown in Fig. Fig. 3 is a graph showing the relationship between the dissolved resin concentration and the CD value when developing is carried out for a predetermined time with six kinds of developing solutions having different concentrations of the dissolution resin (resin component constituting the photoresist) (2.38 wt% of TMAH actually used) As shown in Fig. 3, when a developing solution having a dissolved resin concentration of 0.2 abs is used with respect to a reference CD value in the case of using a developer having a dissolved resin concentration O abs (a resin in which the resin is not dissolved), the CD value Is increased by 0.04 mu m, and when a developer having a dissolved resin concentration of 0.8 abs is used, the CD value increases by 0.288 mu m. That is, the relationship shown in Fig. 3 shows that the solubility of the developer in the photoresist is lowered to a constant tendency as the concentration of the dissolved resin in the developer increases, and the CD value increases in a constant relationship.

The relationship between alkali concentration, carbonate concentration, and dissolved resin concentration can be found from experiments in a developer in which the CD value is kept constant. In order to discover the above relationship, a plurality of developing solutions (for example, a practically used TMAH aqueous solution) different in alkali concentration, which do not contain a carbonate and a resin component (a resin component constituting the photoresist), and a carbonate and the resin component (I) and (II) were carried out for each developer, and the CD values of the obtained resist patterns were compared with the CD values . With respect to the carbonate concentration of the developing solution having different alkali concentration, it is adjusted to an appropriate value of, for example, 100 to 2000 ppm by the addition of dry ice in the same manner as described above, and the dissolved resin concentration of each developing solution is measured The alkali concentration and the dissolved resin concentration are adjusted to, for example, 100 ppm / 0 abs, 250 ppm / 0.3 abs, 500 ppm / 0.6 abs, and 1000 ppm / 0.9 abs, respectively, by dissolving the photoresist in a calculated amount.

From the obtained results, it is possible to estimate the relational expression by, for example, multifactorial analysis of the variation of the CD value as a dependent variable and the alkali concentration, the carbonate concentration and the dissolved resin concentration as the independent variables by statistical processing. As a result, when TMAH is used as the developing solution, it is possible to exhibit solubility such that the required correction amount of the alkali concentration in the developer (shortage of the alkali concentration to the reference concentration as described above), that is, the CD value becomes a constant value The amount of correction of the alkali concentration can be expressed by the following approximate expression. In the following formulas, the numerical value of the TMAH concentration (y) represents the deficiency with respect to the reference concentration.

expression( III )

y = (2.33 x 10 ^-6 x ² + 6.36 x 10 ^-4 x + 0.36 c) /8.79 (III)

Where x is the carbonate concentration (ppm), c is the dissolved resin concentration (abs), and y is the TMAH concentration (wt%).

The unit abs (absorbance) of the concentration of the dissolved resin is a unit of a dimensionless amount so as to indicate the concentration of the substance in the liquid by the absorbance, which is a scale indicating the absorption intensity of the substance with respect to a specific wavelength light, The concentration can be expressed by the absorbance at an absorption wavelength (for example, 560 nm) unique to the dissolution resin.

In the present invention, the alkali concentration of the developer, the carbonate concentration in the developer, and the concentration of the dissolved resin are measured, and the alkali concentration is adjusted according to the carbonate concentration and the dissolved resin concentration in the developer based on the formula (III). In other words, the alkali concentration is adjusted to a value equal to or higher than the reference concentration according to the measured value of the carbonate concentration. Thus, the solubility of the developer can be kept constant, the dimensional accuracy of the resist pattern can be further increased, and the CD value can be further controlled constantly.

In carrying out the present invention in the above-described production apparatus or the like, it is necessary to determine the actual alkali concentration in accordance with the carbonate concentration and the dissolved resin concentration as a constant CD value is obtained in the concentration control of the developer. In this case, the alkali concentration is adjusted on the basis of the previously prepared relationship between the alkali concentration, the carbonate concentration and the dissolved resin concentration, which can exhibit solubility so that the CD value becomes a constant value. The above relationship can be expressed by the following approximate expression when TMAH is used:

expression( IV )

y = (2.33 x 10 ^-6 x ² + 6.36 x 10 ^-4 x + 0.36 c) /8.79 + 2.38 (IV)

Where x is the carbonate concentration (ppm), c is the dissolved resin concentration (abs), and y is the TMAH concentration (wt%).

The apparatus for producing a preferred embodiment of the present invention is similar to the apparatus of the above-described embodiment in the same manner as the apparatus of the above-described embodiment except that the apparatus 1, the supply line 2, the recovery line 3, the undiluted solution supply line 6, . In this case, as the concentration meter 5, a multicomponent densitometer for detecting the alkali concentration of the developer in the production tank, the carbonate concentration in the developer, and the dissolved resin concentration is used. In addition, the above-described control device controls the concentration of alkali, the carbonate concentration and the dissolved resin concentration, which can exhibit solubility so that the alkali concentration, the carbonate concentration, the dissolved resin concentration, and the CD value of the developer measured by the concentration meter 5 become a constant value And controls the supply of the developer stock solution to adjust the alkali concentration.

As the densitometer 5, a multi-component densitometer the same as that described above in which the function of measuring the dissolved resin concentration is added can be used. The multi-component densitometer is based on the principle that the propagation speed, the electronic conductivity and the absorbance of the ultrasonic wave in the liquid are uniquely specified according to the concentration of each component of the alkali, carbonate and dissolution resin when the temperature of the solution is constant. The multi-component densitometer measures the concentration of the developer, the propagation speed of the ultrasonic wave, the electronic conductivity and the absorbance, and calculates the relationship between the ultrasonic wave propagation speed, the electronic conductivity and the absorbance at a predetermined temperature, alkali concentration, carbonate concentration, A matrix in which the relationship between the ultrasound propagation velocity, the electronic conductivity and the absorbance measured in advance under a predetermined temperature condition is determined for each combination of the prepared alkali concentration, carbonate concentration and dissolved resin concentration), the alkali concentration of the developer, the carbonate concentration in the developer And the dissolved resin concentration.

In the production apparatus of the present invention, in the same manner as in the apparatus of the above embodiment, based on the alkali concentration of the developer measured by the concentration meter 5, the carbonate concentration in the developer, and the dissolved resin concentration, 6), and adjusts the alkali concentration to a predetermined target value by adding a stock solution of the developer corresponding to the deficiency of the alkali concentration.

In the case where the alkali concentration becomes too high in view of the above relationship (relation of the formula (VI)), pure water for dilution is supplied to the production tank 1 through the dilution water supply line 7 in the same manner as in the above- do. On the other hand, when the amount of the developer in the production tank 1 is reduced, the developer stock solution and pure water are supplied to the production tank 1 through the stock solution supply line 6 and the dilution water supply line 7, A new developing solution is supplied to the production tank 1 through the photoresist 8 and the alkali concentration is adjusted by the above operation.

As described above, the alkaline concentration of the developer, the carbonate concentration in the developer, and the dissolved resin concentration are measured as described above, and the relationship between the alkali concentration, the carbonate concentration, and the dissolved resin concentration, which can exhibit solubility so that the CD value becomes a constant value, To adjust the alkali concentration. In this way, the solubility of the developer in the photoresist, that is, the development speed can be kept more constant. Therefore, according to the present invention, the dimensional accuracy and the film thickness accuracy of the resist pattern formed in the developing process can be further increased.

As described above, according to the present invention, since the dimensional accuracy and the film thickness accuracy of the resist pattern can be further increased in the developing process, it is possible to perform a high-quality developing process. As a result, it is possible to form the pattern on the substrate with high accuracy in the etching process. In addition, since the alkali concentration is gradually increased in accordance with the increase of the carbonate concentration in the developing solution, the recycling rate of the developing solution can be increased and the developing process can be further stabilized. Further, according to the production apparatus of the present invention, it is possible to produce a developer capable of performing a high-quality development process by using the spent developer recovered from the development process. Since the developing solution obtained by the concentration adjusting method and the manufacturing apparatus of the present invention maintains a constant developing speed with respect to the photoresist, high quality developing processing can be performed.

Therefore, a prescribed development treatment was performed using a newly prepared developer containing no carbonate (TMAH having a concentration of 2.38% by weight actually used), and the obtained resist pattern was confirmed to have a CD value of 4.00 탆. On the other hand, several used developers having a carbonate concentration of 100 to 2000 ppm were prepared, the TMAH concentration was adjusted on the basis of the relationship of the aforementioned formula (II), and the same development processing As a result, the CD value was 4.00 mu m even when a developer was used. As a result, it was confirmed that a certain solubility can be maintained by adjusting the alkali concentration based on the relationship of the formulas (I) and (II) (the relationship shown in FIG. 1).

In addition, several kinds of spent developers having a carbonate concentration of 100 to 2000 ppm and a dissolved resin concentration of 0 to 2.0 abs were prepared and the TMAH concentration was adjusted based on the relationship of the above formula (IV). As a result of carrying out the same developing treatment as above using each developer, the CD value was 4.00 mu m even when a developer was used. As a result, it has been confirmed that the solubility can be more constantly maintained by adjusting the alkali concentration based on the relationship of the formulas (III) and (VI) with respect to the developer in which the resin is dissolved.

Claims (14)

A method for controlling an alkali concentration of an alkaline developer used for developing a photoresist, the method comprising the steps of: measuring the alkali concentration of the developer, the carbonate concentration in the developer, and the concentration of the dissolved resin The alkali concentration, the alkali concentration, the carbonate concentration, and the dissolved resin concentration, which are capable of exhibiting solubility so that the CD value obtained by the development processing becomes a constant value, Wherein the concentration of the developer in the developer y = (2.33 x 10 ^-6 x ² + 6.36 x 10 ^-4 x + 0.36 c) /8.79 + 2.38 Where x is the carbonate concentration (ppm), c is the dissolved resin concentration (abs), and y is the TMAH concentration (wt%). The method according to claim 1, wherein the concentration of alkali in the developing solution, the concentration of carbonate in the developing solution, and the concentration of the dissolved resin are measured as a concentration meter, the ultrasonic wave propagation speed, the electronic conductivity and the absorbance of the developing solution are measured, , A concentration control method of a developer using a multi-component concentration meter capable of detecting the alkali concentration of the developer, the carbonate concentration in the developer, and the dissolved resin concentration based on the relationship between the ultrasonic wave propagation velocity, the electronic conductivity and the absorbance in the carbonate concentration and the dissolved resin concentration . An apparatus for producing an alkaline developer for use in developing a photoresist, the apparatus comprising: a tank for producing an alkaline component of tetra methyl ammonium hydroxide, a developer in a predetermined concentration, A supply line, a recovery line for receiving spent developer in said manufacturing tank, a raw solution supply line for supplying a new developer solution having an alkali concentration higher than the reference concentration to said production tank, an alkali concentration of the developer in said production tank, And a control device for controlling the supply of the developer stock solution from the stock solution supply line on the basis of the concentration detected by the concentration meter, wherein the control device controls the concentration of the developer measured by the concentration meter Alkali concentration, carbonate concentration in developer Based on a relationship expressed by an approximate expression prepared in advance of the alkali concentration, the carbonate concentration and the dissolved resin concentration, which can exhibit solubility so that the CD value obtained by the development processing becomes a constant value, And controlling the supply of the alkaline developer to the developing roller to adjust the alkali concentration. y = (2.33 x 10 ^-6 x ² + 6.36 x 10 ^-4 x + 0.36 c) /8.79 + 2.38 Where x is the carbonate concentration (ppm), c is the dissolved resin concentration (abs), and y is the TMAH concentration (wt%). The method according to claim 3, wherein the concentration meter measures the ultrasonic wave propagation velocity, the electronic conductivity and the absorbance of the developer in the developer, and measures the ultrasonic wave propagation velocity, the electronic conductivity and the absorbance at a predetermined temperature, alkali concentration, carbonate concentration, Component concentration system capable of detecting the alkali concentration of the developer, the carbonate concentration in the developer, and the concentration of the dissolved resin on the basis of the relationship. delete delete delete delete delete delete delete delete delete delete

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