JP2008283162A - Method of adjusting concentration of liquid developer, preparation device of liquid developer, and liquid developer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of adjusting concentration of liquid developer and a preparation device of the liquid developer capable of adjusting alkaline concentration of alkaline liquid developer used in a developing process of photoresist so as to develop with high quality. <P>SOLUTION: The method of adjusting concentration of liquid developer comprise a step of measuring an alkaline concentration and a concentration of a carbonate in the liquid developer; and a step of adjusting the alkaline concentration base on predetermined relationship the alkaline concentration and the concentration of the carbonate that can achieve dissolution capability so that the CD value obtained from the developing process is constant. The preparation device for the liquid developer comprises a preparation vessel, a feed line for feeding the liquid developer to the developing process, a recovery line for receiving used liquid developer, a stock solution supply line for feeding new liquid developer stocked to the preparation vessel, a densitometer for detecting the alkaline concentration and the concentration of carbonate in the liquid developer and a controller for controlling the feed of the original liquid developer based on a specific relationship. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a developer concentration adjusting method and preparation apparatus, and a developer, and more specifically, an alkali concentration of an alkaline developer used for developing a photoresist in a manufacturing process of a liquid crystal substrate, a printed circuit board, and the like. A developer adjusting method for adjusting the concentration to an optimum concentration so that a constant development speed can be maintained and higher quality development processing can be performed, and a developer suitable for carrying out the concentration adjusting method. And a developer obtained by these concentration adjusting methods and preparation devices.

  An alkaline aqueous solution containing tetramethylammonium hydroxide (TMAH) or the like as a main component is used as a developing solution for developing a photoresist in a manufacturing process of a liquid crystal substrate, a printed circuit board, or the like. Such an alkaline developer has recently been used in large quantities due to the increase in the substrate size and the progress of the process. From the viewpoint of cost reduction, the used developer is recovered and supplied to the development process. . However, as the process is repeated, the alkali concentration decreases due to the reaction with the acid in the resist and the reaction with carbon dioxide gas and oxygen in the air during the process stop, etc. Since the film thickness accuracy of the exposed portion is lowered, it is important to keep the alkali concentration constant.

Concerning the developer concentration management, for example, an apparatus for managing an alkaline developer used for developing a photoresist, which circulates and supplies the developer to the developing device, and also circulates the alkali concentration of the developer. In addition, a “developer management apparatus” is disclosed in which both the concentration of dissolved resin in the developer and the concentration of the developer in the developer are controlled at the same time to prevent deterioration of the development performance. In such a developer management device, the dissolved resin concentration in the developer is detected by an absorptiometer, the alkali concentration of the developer is detected by a conductivity meter, and the alkali concentration, dissolved resin concentration and the development in the device are detected. The developer in the apparatus is discharged so that the level of the solution is constant, and the developer solution and pure water are replenished, or a newly prepared developer is replenished. .
Japanese Patent No. 2561578

  By the way, in the production of a substrate, when the development treatment and the etching treatment are performed despite the fact that the alkali concentration of the developer and the concentration of the dissolved resin in the developer are controlled to be constant, they are formed on the photomask or the substrate. There is a phenomenon that the line width of a pattern such as a circuit varies. In fact, when the developer is recycled, the line width (CD value) of a photoresist pattern such as a circuit formed on the substrate by the development process tends to gradually deviate from the reference value (design value). That is, in the development process, as the process is repeated, the development speed, in other words, the dissolution rate with respect to the photoresist fluctuates, and the dimensional accuracy of the resulting resist pattern gradually decreases. As a result, the line width of the pattern formed on the substrate by etching is affected. Therefore, in the supply management of the developer, an improved management method that does not cause fluctuations in the development speed is desired.

  The present invention has been made in view of the above circumstances, and its purpose is to adjust the concentration of an alkaline developer used for developing a photoresist in a manufacturing process of a liquid crystal substrate, a printed circuit board, etc. Another object of the present invention is to provide a developer concentration adjusting method capable of maintaining a constant development speed and capable of higher quality development processing. Another object of the present invention is to provide an apparatus for preparing a developer that can use an alkaline spent developer recovered from a photoresist development process to prepare a developer capable of higher quality development processing. There is to do. Furthermore, another object of the present invention is an alkaline developer obtained by using the above-described density adjusting method and preparation apparatus and effectively using a used developer, and capable of developing with a high quality. To provide liquid.

  In order to solve the above-mentioned problems, the present inventors have made various studies. As a result, although the alkali concentration is maintained at the reference concentration and the dissolved resin concentration is controlled in the developer, carbon dioxide in the air is mainly used. It was confirmed that the carbonate produced in the developing solution by absorbing the water offsets the dissolving ability of the developing solution and decreases the dissolution rate of the developing solution. Furthermore, as a result of examining the influence of carbonate on the solubility of the developer by paying attention to the relationship between the CD value and the carbonate concentration in the developer, the carbonic acid was not affected by changes in the dissolved resin concentration. It has been found that the solubility of the developer decreases with a certain tendency as the salt concentration increases. As the carbonate concentration in the developer increases, it is found that if the concentration is adjusted to increase the alkali concentration based on a specific relationship, the solubility of the developer in the photoresist can be maintained constant. The present invention has been completed.

  That is, the first gist of the present invention is a concentration adjusting method for adjusting the alkali concentration of an alkaline developer used for developing a photoresist, wherein the alkali concentration of the developer and the carbonate concentration in the developer are as follows. And adjusting the alkali concentration based on a pre-created relationship between an alkali concentration and a carbonate concentration capable of exhibiting a dissolving ability such that the CD value obtained by development processing becomes a constant value. And a developer density adjusting method.

  The second gist of the present invention is a preparation apparatus for preparing an alkaline developer used for developing a photoresist, a preparation tank for preparing a developer having a predetermined concentration, and the prepared developer. A supply line for supplying the developer to the development process, a collection line for receiving the used developer in the preparation tank, a stock supply line for supplying a new developer stock solution having an alkali concentration higher than a reference concentration to the preparation tank, A concentration meter for detecting the alkali concentration of the developer in the preparation tank and the carbonate concentration in the developer, and a control for controlling the supply of the developer raw solution from the stock solution supply line based on the detected concentration by the concentration meter And the control device is configured so that the alkali concentration of the developer measured by the densitometer and the carbonate concentration in the developer and the CD value obtained by the development process become constant values. A developer characterized by having a function of adjusting the alkali concentration by controlling the supply of a developer stock solution based on a pre-created relationship between an alkali concentration capable of exhibiting a dissolving ability and a carbonate concentration. In the preparation apparatus.

  Furthermore, in the present invention, in order to adjust the alkali concentration with higher accuracy, the alkali concentration may be adjusted in consideration of the dissolved resin concentration together with the carbonate concentration in the developer. That is, the third gist of the present invention is a concentration adjusting method for adjusting the alkali concentration of an alkaline developer used for developing a photoresist, wherein the alkali concentration of the developer and the carbonate concentration in the developer are as follows. And based on a pre-created relationship between alkali concentration, carbonate concentration, and dissolved resin concentration that can exhibit the dissolving ability such that the dissolved resin concentration is measured and the CD value obtained by development processing becomes a constant value, The present invention resides in a developer concentration adjusting method characterized by adjusting the alkali concentration.

  The fourth gist of the present invention is a preparation device for preparing an alkaline developer used for developing a photoresist, a preparation tank for preparing a developer having a predetermined concentration, and the prepared developer. A supply line for supplying the developer to the development process, a collection line for receiving the used developer in the preparation tank, a stock supply line for supplying a new developer stock solution having an alkali concentration higher than a reference concentration to the preparation tank, A concentration meter for detecting the alkali concentration of the developer in the preparation tank, the carbonate concentration and the dissolved resin concentration in the developer, and supply of the developer stock solution from the stock solution supply line based on the detected concentration by the concentration meter And a control device for controlling the alkali concentration of the developer measured by the densitometer, the carbonate concentration and the dissolved resin concentration in the developer, and a development process. The supply of the developer stock solution is controlled to control the alkali concentration based on the pre-created relationship between the alkali concentration, carbonate concentration, and dissolving resin concentration that can exhibit the dissolving ability so that the CD value becomes a constant value. It exists in the preparation apparatus of the developing solution characterized by having the function to adjust.

  According to the present invention, as the carbonate concentration in the developer increases, the alkali concentration of the developer is adjusted based on a specific relationship, and the solubility of the developer in the photoresist is maintained constant. In this development process, a constant development speed can be maintained, and a higher quality development process is possible. Further, by adjusting the alkali concentration of the developer based on a specific relationship in accordance with the carbonate concentration and the dissolved resin concentration in the developer, further high-quality development processing becomes possible.

  An embodiment of a developer concentration adjusting method and a developer preparing apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a graph showing the relationship between the carbonate concentration and the deficiency of the alkali concentration with respect to the reference concentration, and the relationship between the carbonate concentration and the alkali concentration capable of exhibiting a predetermined solubility. FIG. 2 is a graph showing the influence of the carbonate concentration in the developer on the line width (CD value) of the photoresist pattern obtained by the development process. FIG. 3 is a graph showing the influence of the concentration of the dissolved resin in the developer on the line width (CD value) of the photoresist pattern obtained by the development process. FIG. 4 is a flowchart showing the main components of the developing solution preparation apparatus according to the present invention.

  A developer concentration adjusting method (hereinafter abbreviated as “density adjusting method”) according to the present invention is used for developing a photoresist in a developing process including a developing device such as a spin developer device or a coater developer device. This is a concentration adjusting method for adjusting the alkali concentration of an alkaline developer (hereinafter abbreviated as “developer”), and also a developer preparing apparatus (hereinafter referred to as “preparation apparatus”) according to the present invention. ) Is a preparation device for preparing the developer, and in the present invention, the used developer recovered from the photoresist development process in the manufacturing process of liquid crystal substrates, printed boards, etc. is reused in the development process. It is suitable when doing.

  In the present invention, as the alkali component of the developer, an inorganic alkaline aqueous solution composed of an inorganic alkali such as potassium hydroxide, sodium hydroxide, sodium phosphate, sodium silicate or a mixture thereof, or tetramethylammonium hydroxide (TMAH) is used. And an organic alkaline aqueous solution such as trimethylmonoethanolammonium hydroxide (choline). When TMAH is used as the developer, the TMAH concentration (alkali concentration) is set to 2.380 wt%, for example. The developer may contain conventionally known additives such as a nonionic surfactant and a fluorine-based surfactant.

  In the present invention, “CD value” refers to the line width of a photoresist pattern obtained on a substrate by development processing. The “reference concentration” of alkali described later refers to an alkali concentration (initial alkali concentration) at which the following CD value is obtained. The above-mentioned CD value is a CD value when a predetermined time of development processing is performed, and is an initial CD value that serves as a guide for evaluation before the value changes. The alkali serving as the reference may be an alkali alone or may contain the above-mentioned additive, and the reference concentration of alkali in the case of using an actual solution containing the additive is It is preferable to take into account the difference in solubility depending on the product.

  First, a preparation apparatus suitable for carrying out the concentration adjusting method of the present invention will be described. As shown in FIG. 4, the preparation apparatus of the present invention is a preparation apparatus for preparing a developer used in the development process, and the developer is prepared using a used developer recovered from the development process. It is made to do. Such a preparation apparatus supplies a developing tank (1) for preparing a developer having a predetermined concentration and a developing process (hereinafter referred to as “developing apparatus”) such as the developing apparatus (9). A supply line (2), a recovery line (3) for receiving the used developer into the preparation tank (1), and a new developer stock solution having an alkali concentration higher than the reference concentration is supplied to the preparation tank (1). Stock solution supply line (6), concentration meter (5) for detecting the alkali concentration of the developer in the preparation tank (1) and the carbonate concentration in the developer, and the stock solution supply line based on the concentration detected by the concentration meter And a control device (not shown) for controlling the supply of the developer stock solution from (6).

  The preparation tank (1) is a supply tank that adjusts the concentration of the developer to a constant target value and supplies the developer whose concentration has been adjusted to the developing device (9) as necessary. It is constituted by a container having a corrosion resistance of about 2000 liters. In the preparation tank (1), a circulation channel (4) provided with a pump (41) is provided as a means for stirring the developer in order to maintain the contained developer at a uniform concentration. The stirring means by circulation as described above generates less particles and can reduce contamination of the developer as compared with a stirring device such as a screw installed in the tank.

  In addition, the collected used developing solution is adjusted to a constant temperature in the developing device (9), and the developing solution in the preparation tank (1) is also maintained at a substantially constant temperature. However, in order to measure the concentration of the developing solution more accurately by the densitometer (5) described later, it is preferable to maintain the temperature of the developing solution in the preparation tank (1) accurately at a constant temperature (for example, 25 ° C.). . Therefore, in a preferred embodiment, the preparation tank (1) or the circulation channel (4) is provided with temperature adjusting means (not shown) including a heater and a cooler.

  The supply line (2) includes a flow path from the preparation tank (1) to the developing device (9) and a pump (21) interposed in the flow path, and the prepared development in the preparation tank (1). The liquid is supplied to the developing device (9). The recovery line (3) is constituted by a flow path from the used developer discharge port (chamber drain) of the developing device (9) to the preparation tank (1), and the flow path or the developing device (9). A used developer is collected in the preparation tank (1) using a pump (not shown) installed on the side. Although not shown, the recovery line (3) may be provided with a buffer tank for temporarily storing the used developer, and the temperature of the used developer may be set in the developing tank (1). In order to adjust the temperature to the same level as the liquid, temperature adjusting means such as a thermostatic bath may be provided.

  The stock solution supply line (6) is composed of a flow path from the stock solution supply mechanism (A) (not shown) to the preparation tank (1) and a flow rate adjusting valve (61) interposed in the flow path. 1) When the concentration of the developing solution in the inside is lowered, the concentration of the developing solution stock higher than the reference concentration, for example, TMAH, is 20 to 25 wt% by the control of the flow rate adjusting valve (61) by the controller described later. The developer stock solution is supplied to the preparation tank (1). The stock solution supply mechanism (A) feeds the developer stock solution from the stock solution storage tank to the above-mentioned flow path to the preparation tank (1), a stock solution storage tank having an internal volume of about 500 to 3000 liters for storing a high concentration developer stock solution in advance. It is mainly composed of a pump that feeds liquid.

  In addition, in the preparation apparatus of the present invention, when the alkali concentration of the developer in the preparation tank (1) becomes higher than the target concentration, the concentration of the developer is lowered. A dilution water supply line (7) is provided. The dilution water supply line (7) is composed of a flow path from the dilution water supply mechanism (B) (not shown) to the preparation tank (1) and a flow rate adjusting valve (71) interposed in the flow path. The ultrapure water is supplied to the preparation tank (1) by controlling the flow rate adjusting valve (71) by the controller. As the dilution water supply mechanism (B), a pure water production apparatus including a storage tank and a liquid feed pump is usually used.

  Furthermore, in the preparation apparatus of the present invention, when the amount of the developer in the preparation tank (1) decreases below a certain amount, the developer is replenished so that a new developer having a reference concentration is prepared in the preparation tank (1). Is provided with a new liquid supply line (8) for supplying to the liquid. The new liquid supply line (8) includes a flow path from the new liquid supply mechanism (C) (not shown) to the preparation tank (1) and a flow rate adjustment valve (81) interposed in the flow path. By controlling the flow rate adjustment valve (81) by the control device, a developing solution having a reference concentration (for example, TMAH having a concentration of 2.38 wt%) is supplied to the preparation tank (1). The new liquid supply mechanism (C) supplies the developer from the new liquid storage tank to the above-mentioned flow path leading to the new liquid storage tank and the preparation tank (1) with an internal volume of about 500 to 3000 liters for storing new developer in advance. It is mainly composed of a pump that feeds liquid.

  In the preparation apparatus of the present invention, the densitometer (5) usually measures the alkali concentration of the developer in the preparation tank (1) and the carbonate concentration in the developer more accurately. 4). As the densitometer (5), a specific densitometer is used in order to measure the density with high accuracy without being affected by the fluctuation of the dissolved resin concentration in the developer. Specifically, the densitometer (5) measures the temperature of the developer, the ultrasonic propagation speed, and the electromagnetic conductivity, and propagates the ultrasonic wave at a predetermined temperature, alkali concentration, and carbonate concentration prepared in advance. A multi-component densitometer capable of detecting the alkali concentration of the developer and the carbonate concentration in the developer based on the relationship (matrix) between speed and electromagnetic conductivity is used.

  The multi-component concentration meter is a concentration meter that can simultaneously measure the concentrations of two components of alkali and carbonate in real time by measuring the ultrasonic propagation velocity and electromagnetic conductivity in a solution at a constant temperature. That is, the multi-component concentration meter is based on the principle that if the temperature of the solution is constant, the propagation speed and electromagnetic conductivity of the ultrasonic wave in the liquid are uniquely specified according to the concentration of each component. For example, when measuring two components, it mainly comprises an ultrasonic transducer, an ultrasonic transmitter, an electromagnetic conductivity converter, an electromagnetic conductivity transmitter, and a microprocessor for performing a predetermined calculation.

  In the multi-component densitometer, when applied to the developer concentration measurement as described above, the ultrasonic propagation velocity and electromagnetic conductivity measured in advance under a constant temperature condition for each combination of alkali concentration and carbonate concentration. By preparing the relationship as a matrix in advance, that is, by writing it in the microprocessor, it is possible to accurately estimate and calculate the alkali concentration and the carbonate concentration from the measured values based on the matrix. Examples of the multi-component concentration meter as described above include a liquid multi-component concentration meter manufactured by Fuji Kogyo Co., Ltd. In addition to the multi-component concentration meter, the concentration meter that measures the alkali concentration includes a concentration meter that uses a refraction method that measures the refractive index of the fluid, and a near infrared method that measures the wavelength in the near infrared region. A densitometer utilizing the neutralization titration can be used as the densitometer for measuring the carbonate concentration.

  In the preparation apparatus of the present invention, in addition to the operation control of the entire apparatus, the supply of the developer stock solution, the supply of diluted water, and the supply of a new developer based on the measurement of the concentration meter (5) as described above are performed. A control device (not shown) for controlling is provided. Such a control device includes an input device that digitally converts the signals of each measuring instrument, an arithmetic processing device such as a program controller and a computer, and an output device that converts a control signal from the arithmetic processing device into an analog signal.

  The control device is configured to control the supply of the developer stock solution from the stock solution supply line (6) based on the concentration detected by the densitometer (5). That is, the control device has a relationship between the alkali concentration of the developer measured by the densitometer (5) and the carbonate concentration in the developer, and a deficiency of the carbonate concentration and the alkali concentration prepared in advance with respect to the reference concentration, In other words, the supply of the developer stock solution is controlled based on a pre-created relationship between the alkali concentration and the carbonate concentration that can exhibit the dissolving ability so that the CD value obtained by the development processing becomes a constant value. And has a function of adjusting the alkali concentration. Thereby, in the preparation apparatus of this invention, a used developing solution is collect | recovered from a developing device (9), and the developing solution of appropriate alkali concentration can be prepared in a preparation tank (1).

  The control device controls the supply of the developer stock solution, the supply of the dilution water from the dilution water supply line (7), and the supply of a new developer from the new solution supply line (8). Configured. Thereby, in the preparation apparatus of this invention, the liquid quantity of the developing solution in a preparation tank (1) can be managed uniformly.

  In the preparation apparatus of the present invention, the inside of the system is sealed with an inert gas such as nitrogen in order to prevent the developer and the developer stock solution from coming into contact with air. Further, in the preparation apparatus of the present invention, in order to keep the amount of liquid in the system constant, a mechanism for discharging the excess used developer outside the system when the developer stock solution is supplied is provided at an appropriate location. Although not shown, for example, a drain channel including a control valve or an overflow device is attached to the preparation tank (1).

  Next, the concentration adjusting method of the present invention will be described together with the function of the above preparation device. In the concentration adjusting method of the present invention, in preparing a developer using the preparation device as described above, first, the used developer discharged from the development device (9) is prepared in a preparation tank by a recovery line (3). While collecting in (1), the developer in the preparation tank (1) (developer including the used developer) is circulated through the circulation channel (4) and mixed with stirring, while the developer is kept constant by the temperature adjusting means. After maintaining the temperature, the alkali concentration of the developer and the carbonate concentration in the developer are measured with a densitometer (5). As the densitometer (5), the aforementioned multi-component densitometer is used.

  After measuring the alkali concentration of the developer in the preparation tank (1) and the carbonate concentration in the developer, the flow rate adjustment valve (61) of the stock solution supply line (6) is controlled by the above-described control device, and the preparation tank The alkali concentration of the developer in (1) is adjusted to an appropriate concentration. In that case, in the present invention, the relationship between the carbonate concentration prepared in advance and the deficiency of the alkali concentration with respect to the reference concentration, that is, the alkali concentration and the carbonic acid capable of exhibiting the dissolving ability such that the CD value becomes a constant value. Based on the previously created relationship with the salt concentration, 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. Thereby, the solubility of the developing solution with respect to a photoresist can be maintained constant. The above idea of the present invention will be described more specifically as follows.

  When the developer is recycled and supplied to the development process, carbon dioxide in the air is absorbed and carbonate is generated in the developer, and the carbonate cancels the solubility of the developer in the photoresist and develops. The dimensional accuracy of the resist pattern obtained by processing is lowered. As a result, the line width of the circuit pattern formed on the substrate is different from the design width. 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 on the CD value is as shown in FIG. FIG. 2 shows that for seven types of developers (TMAH) having different carbonate concentrations, the alkali concentration (TMAH concentration) is adjusted to 3 to 5 types in the range of 2.20 to 3.27 wt%. The relationship between the CD value when developing for a certain time for each concentration and the carbonate concentration in the developer was confirmed. As shown in FIG. 2, a newly prepared carbonate concentration of 0 ppm was prepared. When developing solutions (5 types with different alkali concentrations) are used, the CD value is 2.77 to 5.16 μm, whereas for example, developing solutions with carbonate concentrations of 525 ppm (4 types with different alkali concentrations) are used. In this case, when a developer having a CD value of 3.70 to 5.05 μm and a carbonate concentration of 1000 ppm (four types having different alkali concentrations) is used, the CD value is 3.59 to 4.30 μm. That is, the relationship shown in FIG. 2 shows that as the carbonate concentration in the developer increases, the solubility of the developer in the photoresist decreases with a certain tendency and the CD value increases with a certain relationship. Yes.

  Therefore, when it is attempted to keep the CD value constant in the development process, it is necessary to increase the alkali concentration according to the carbonate concentration. For example, if the CD value is set to 4.00 μm, the alkali concentration (TMAH concentration) is adjusted to 2.38 wt% (reference concentration) when using a newly prepared developer having a carbonate concentration of 0 ppm. However, when using a developer with a carbonate concentration of 500 ppm, the alkali concentration (TMAH concentration) must be adjusted to 2.50 wt%, and when using a developer with a carbonate concentration of 1000 ppm, the alkali concentration (TMAH concentration) must be adjusted to 2.71 wt%.

  From the above relationship, regarding the alkali concentration required in the developer, the relationship between the carbonate concentration and the required correction amount of the alkali concentration when the CD value is kept constant (the shortage of the alkali concentration with respect to the reference concentration) The relationship can be expressed as shown in FIG. The relationship between the carbonate concentration and the shortage of the alkali concentration with respect to the reference concentration is determined in advance from the relationship between the alkali concentration and the carbonate concentration when performing the prescribed development processing (processing for obtaining a constant CD value) as described above. This is a derived relationship, which means a relationship between a carbonate concentration and a deficiency with respect to a reference alkali concentration (concentration of the developer when a newly prepared developer not containing carbonate is used). In the graph of FIG. 1, the numerical value in the parenthesis of the TMAH concentration (alkali concentration) on the vertical axis indicates a deficiency of the concentration relative to the reference concentration (2.38 wt%).

  As described above, the present invention pays attention to the relationship between the alkali concentration and the carbonate concentration in the developer when the CD value is kept constant, and corrects the reference alkali concentration according to the carbonate concentration. It is a thing. When TMAH is used, the correction amount (shortage of the carbonate concentration and the alkali concentration relative to the reference concentration) shown in FIG. 1 can be expressed by the following approximate expression.

  In order to confirm the relationship shown in FIG. 2 and to find the above approximate expression and the relationship shown in FIG. 1, a plurality of newly prepared developers having different alkali concentrations not containing carbonate (for example, actually used) TMAH aqueous solution) and a plurality of types of developers as carbonate-containing samples having different alkali concentrations, and a prescribed development process with a constant temperature and development time is performed for each developer, The CD value of the obtained resist pattern is measured. At that time, for each alkali concentration developer containing carbonate, by adding a calculated amount of dry ice while confirming the carbonate concentration, the carbonate concentration is, for example, 100 ppm, 325 ppm, 500 ppm, 1000 ppm, 1500 ppm, 2000 ppm. A plurality of types are prepared as follows. Then, the relational expression is estimated by statistical processing from the obtained result.

  In the present invention, based on the above formula (I) (the relationship of the graph illustrated in FIG. 1), that is, between the alkali concentration and the carbonate concentration capable of exhibiting the dissolving ability such that the CD value becomes a constant value. Based on the relationship created in advance, 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. Thereby, the dissolving ability of the developer can be maintained constant, the dimensional accuracy of the resist pattern can be increased, and the CD value can be controlled to be constant. When the carbonate concentration in the developer is 0 ppm, the alkali concentration is set to the reference concentration.

  Further, in carrying out the present invention in a preparation apparatus or the like, in adjusting the concentration of the developer, it is necessary to determine the actual alkali concentration according to the carbonate concentration so that a constant CD value can be obtained. In that case, the relationship between the carbonate concentration prepared in advance and the alkali concentration capable of exhibiting a predetermined dissolving ability, that is, the alkali concentration and the carbonate concentration capable of exhibiting the dissolving ability such that the CD value becomes a constant value, The alkali concentration is adjusted based on the previously created relationship (the relationship between the carbonate concentration and the alkali concentration with the above-mentioned shortage added). The above relationship is shown as the relationship between the carbonate concentration on the horizontal axis and the TMAH concentration on the vertical axis in the graph of FIG. Therefore, when TMAH is used, the above relationship (the relationship between the carbonate concentration and the alkali concentration capable of exhibiting a predetermined solubility) can be expressed by the following approximate expression.

  In the preparation apparatus of the present invention, an algorithm for density measurement and control calculation is written in the control apparatus, and in the concentration adjustment in the preparation tank (1), the alkali concentration of the developer measured by the concentration meter (5) and development Based on the carbonate concentration in the solution, the flow rate adjustment valve (61) of the stock solution supply line (6) is controlled according to the above formula (II), and the developer stock solution corresponding to the shortage of alkali concentration is added to adjust the alkali concentration. Adjust to a predetermined target value. When the alkali concentration becomes too high in light of the above relationship (the relationship of the formula (II)), pure water for dilution is supplied to the preparation tank (1) through the dilution water supply line (7).

  When the amount of the developer in the preparation tank (1) is reduced by discharging a part of the collected used developer, the stock solution supply line (6) and the dilution water supply line (7) Through this, the developer stock solution and pure water are supplied to the preparation tank (1), and the alkali concentration is adjusted by the above-described operation, thereby adjusting the liquid amount in the preparation tank (1) within a certain range. Alternatively, a new developer is supplied to the preparation tank (1) through the new solution supply line (8) to adjust the amount of solution.

  The supply control of the developer solution, the supply control of the dilution water, and the supply control of the new developer are respectively the supply amount of the developer solution from the stock solution supply mechanism (A) and the pure solution from the dilution water supply mechanism (B)). This is performed by cascade-controlling the amount of water supplied and the amount of developer supplied from the new solution supply line (8). In these controls, for example, a so-called asymptotic method disclosed in “Dilution Method and Dilution Device of Alkali Development Stock Solution” described in Japanese Patent No. 374081 can be used.

  Specifically, for example, in the adjustment of the alkali concentration in the preparation tank (1) using the asymptotic method, the developer in the preparation tank (1) in which the alkali concentration is lowered (or the alkali concentration is high) is increased. A concentration measuring step of measuring the concentration of the developing solution by the densitometer (5) when adding a developing solution stock solution (or diluting water) having a concentration, and the concentration measured in the concentration measuring step and the target concentration Based on the difference (concentration obtained from the above formula (II)), the shortage amount of the developer stock solution (or the addition amount of dilution water) is calculated, and 85 to 99% of the calculated shortage amount (or addition amount). And preferably a preparation step for supplying an amount corresponding to 92-98%. Then, the preparation step is repeated from the concentration measurement step until the measured concentration reaches a value within a preset target concentration range. Thereby, the alkali concentration in the developing solution in the preparation tank (1) can be managed with higher accuracy.

  As described above, in the present invention, based on the relationship between the carbonate concentration prepared in advance and the shortage of the alkali concentration with respect to the reference concentration, the alkali concentration is set to a value equal to or higher than the reference concentration according to the measured value of the carbonate concentration. Adjust. That is, the alkali concentration is adjusted based on a previously created relationship between an alkali concentration and a carbonate concentration that can exhibit a dissolving ability such that the CD value becomes a constant value. Thereby, the solubility of the developing solution with respect to the photoresist is kept constant. Therefore, according to the present invention, it is possible to maintain a constant development speed for the photoresist in the development process, and to further increase the dimensional accuracy and film thickness accuracy of the resist pattern created in the development process. Higher quality development processing becomes possible.

  In the present invention, in order to adjust the alkali concentration with higher accuracy, the alkali concentration may be adjusted according to the dissolved resin concentration together with the carbonate concentration in the developer. As described above, when the developer is recycled, carbonate is generated in the developer, and the photoresist is dissolved in the developer by the development process, and the dissolved resin has the ability to dissolve the developer. There is a slight tendency to decrease. Therefore, when adjusting the alkali concentration as described above, it is preferable to correct according to the dissolved resin concentration in the developer.

  The influence of the dissolved resin concentration in the developer on the CD value is as shown in FIG. FIG. 3 shows the concentration of dissolved resin when it is developed for a certain period of time with six types of developers (TMAH having an actual concentration of 2.38 wt%) having different concentrations of dissolved resin (resin component constituting the photoresist). FIG. 3 shows the relationship of changes in the CD value. As shown in FIG. 3, with respect to the reference CD value when a developer having a dissolved resin concentration of 0 abs (a developer in which the resin is not dissolved) is used. For example, the CD value increases by 0.04 μm when a developer with a dissolved resin concentration of 0.2 abs is used, and the CD value increases by 0.288 μm when a developer with a dissolved resin concentration of 0.8 abs is used. That is, the relationship shown in FIG. 3 indicates that as the concentration of the dissolved resin in the developer increases, the solubility of the developer in the photoresist decreases with a certain tendency and the CD value increases with a certain relationship. Yes.

  Therefore, the relationship among the alkali concentration, carbonate concentration, and dissolved resin concentration in the developer when the CD value is kept constant can be found from experiments. In order to find the above relationship, a plurality of types of newly prepared developers having different alkali concentrations (for example, TMAH aqueous solution actually used) which do not contain carbonate and resin components (resin components constituting photoresist) are included. And a plurality of types of developers as samples containing carbonate and the above-mentioned resin components and having different alkali concentrations, and carrying out the same prescribed development processing as that for deriving the above formulas (I) and (II) This is performed for each developer, and the CD value of the obtained resist pattern is measured. The carbonate concentration of each developer having different alkali concentrations is adjusted to an appropriate value of, for example, 100 to 2000 ppm by adding dry ice as in the case described above, and the dissolved resin concentration of each developer is 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, 1000 ppm / 0.9 abs by dissolving the calculated amount of the photoresist while measuring the dissolved resin concentration. .

  Then, from the obtained results, a relational expression is obtained by performing a multi-factor analysis by using a statistical process, for example, with the variation amount of the CD value as a dependent variable and the alkali concentration, the carbonate concentration and the dissolved resin concentration as independent variables. Can be estimated. Thus, for example, when TMAH is used as a developing solution, the necessary correction amount of alkali concentration in the developing solution (deficiency with respect to the reference concentration of alkali concentration as described above), that is, dissolution so that the CD value becomes a constant value. The correction amount of the alkali concentration for exhibiting the performance can be expressed by the following approximate expression. In the following formula, the numerical value of the TMAH concentration (y) indicates a shortage with respect to the reference concentration.

  As is well known, the dissolved resin concentration unit abs (absorbance) is a unit of a dimensionless quantity that expresses the concentration of a substance in a liquid by absorbance, which is a measure indicating the absorption intensity of the substance with respect to light of a specific wavelength. The dissolved resin concentration in the developer can be expressed by absorbance at an absorption wavelength (for example, 560 nm) peculiar to the dissolved resin.

  In the present invention, the alkali concentration of the developer, the carbonate concentration and the dissolved resin concentration in the developer are measured, and the alkali concentration is determined according to the carbonate concentration and the dissolved resin concentration in the developer based on the above formula (III). Adjust the concentration. 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 dissolution ability of the developer can be maintained constant, the dimensional accuracy of the resist pattern can be further increased, and the CD value can be further controlled to be constant.

  In carrying out the present invention in the above-described preparation apparatus, the actual alkali concentration is determined in accordance with the carbonate concentration and the dissolved resin concentration so that a constant CD value can be obtained in the developer concentration adjustment. There is a need. In that case, the alkali concentration is adjusted based on a previously created relationship between an alkali concentration, a carbonate concentration, and a dissolved resin concentration capable of exhibiting a dissolving ability such that the CD value becomes a constant value. The above relationship can be expressed by the following approximate expression when TMAH is used.

  The preparation apparatus of the preferable aspect of this invention is the preparation tank (1), supply line (2), recovery line (3), stock solution supply line (6), concentration meter (5), and the apparatus of the above-mentioned aspect. Consists of a control device. In that case, as the densitometer (5), a multi-component densitometer that detects the alkali concentration of the developer in the preparation tank, the carbonate concentration in the developer, and the dissolved resin concentration is used. Then, the above control device exhibits the dissolving ability such that the alkali concentration of the developer measured by the densitometer (5), the carbonate concentration and the dissolved resin concentration in the developer, and the CD value are constant values. It has a function of adjusting the alkali concentration by controlling the supply of the developer stock solution based on the possible relationship between the alkali concentration, carbonate concentration, and dissolved resin concentration.

  As the densitometer (5), a multi-component densitometer similar to that described above to which a function for measuring the dissolved resin concentration is added can be used. Such multi-component densitometers uniquely specify the ultrasonic wave propagation speed, electromagnetic conductivity, and absorbance according to the concentrations of alkali, carbonate, and dissolved resin components when the solution temperature is constant. It is based on the principle of being done. The above multi-component concentration meter measures the temperature, ultrasonic propagation speed, electromagnetic conductivity and absorbance of the developer, and the ultrasonic propagation speed at a predetermined temperature, alkali concentration, carbonate concentration and dissolved resin concentration. (Relationship between ultrasonic propagation velocity, electromagnetic conductivity, and absorbance measured in advance at a constant temperature for each combination of alkali concentration, carbonate concentration, and dissolved resin concentration prepared in advance) Based on the matrix), the alkali concentration of the developer, the carbonate concentration and the dissolved resin concentration in the developer are detected.

  In the preparation apparatus of the present invention, based on the alkali concentration of the developer measured by the densitometer (5), the carbonate concentration and the dissolved resin concentration in the developer, According to the formula (VI), the flow rate adjusting valve (61) of the stock solution supply line (6) is controlled, and a developer stock solution corresponding to the shortage of alkali concentration is added to adjust the alkali concentration to a predetermined target value.

  In addition, when the alkali concentration becomes too high in light of the above relationship (the relationship of the formula (VI)), in the same manner as in the above-described apparatus, the diluting water supply line (7) is used to supply the preparation tank (1). Supply pure water for dilution. On the other hand, when the amount of the developing solution in the preparation tank (1) is reduced, the developing solution stock solution and pure water are supplied to the preparation tank (1) through the stock solution supply line (6) and the dilution water supply line (7). Then, a new developer is supplied to the preparation tank (1) through the new solution supply line (8), and the alkali concentration is adjusted by the above operation.

  In the present invention, as described above, the alkali concentration of the developer, the carbonate concentration in the developer, and the dissolved resin concentration are measured, and the alkali concentration capable of exhibiting the dissolving ability so that the CD value becomes a constant value; The alkali concentration is adjusted based on a pre-created relationship between the carbonate concentration and the dissolved resin concentration. Thereby, the dissolving ability of the developer with respect to the photoresist, that is, the developing speed can be kept more constant. Therefore, according to the present invention, the dimensional accuracy and film thickness accuracy of the resist pattern created in the development process can be further increased.

  As described above, according to the present invention, the dimensional accuracy and film thickness accuracy of the resist pattern can be further improved in the development processing, so that higher quality development processing can be performed. As a result, a pattern can be formed on the substrate with higher accuracy in the etching process. Furthermore, since the alkali concentration is gradually set higher as the carbonate concentration in the developer increases, the recycling rate of the developer can be increased and the development process can be made more stable. Further, according to the preparation apparatus of the present invention, it is possible to prepare a developing solution that can be developed with higher quality by using the used developing solution recovered from the developing process. Since the developer obtained by the concentration adjusting method and the preparation apparatus of the present invention maintains a constant development speed for the photoresist, high-quality development processing can be performed.

  Incidentally, when the prescribed development processing was performed using a newly prepared developer containing no carbonate (TMAH having a concentration of 2.38 wt% actually used), and the obtained resist pattern was confirmed, The CD value was 4.00 μm. On the other hand, several kinds of spent developers having a carbonate concentration of 100 to 2000 ppm are prepared, the TMAH concentration is adjusted based on the relationship of the above-described formula (II), and each developer is used in the same manner as described above. As a result of the development processing, the CD value was 4.00 μm when any of the developing solutions was used. Thereby, it was confirmed that a constant 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).

  Further, several types of used 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). And as a result of performing the same development processing as described above using each developer, the CD value was 4.00 μm in any of the developers. As a result, it was confirmed that the solubility of the developer in which the resin was dissolved could be maintained more constant by adjusting the alkali concentration based on the relationship of the formulas (III) and (VI).

It is a graph which shows the relationship between the shortage with respect to the reference | standard density | concentration of carbonate concentration and alkali concentration, and the relationship between carbonate concentration and the alkali concentration which can exhibit predetermined solubility. It is a graph which shows the influence of the carbonate density | concentration in a developing solution with respect to the line width (CD value) of the photoresist pattern obtained by image development. It is a graph which shows the influence of the melt | dissolution resin density | concentration in a developing solution with respect to the line width (CD value) of the photoresist pattern obtained by image development. It is a flowchart which shows the main components of the preparation apparatus of the developing solution which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1: Preparation tank 2: Supply line 21: Pump 3: Recovery line 4: Circulation flow path 41: Pump 5: Concentration meter 6: Concentration supply line 61: Flow rate adjustment valve 7: Dilution water supply line 71: Flow rate adjustment valve 8: New liquid supply line 81: Flow rate adjusting valve 9: Developing device A: Stock solution supply mechanism B: Dilution water supply mechanism C: New liquid supply mechanism

Claims (14)

  A concentration adjusting method for adjusting the alkali concentration of an alkaline developer used for developing a photoresist, a CD obtained by measuring the alkali concentration of the developer and the carbonate concentration in the developer and developing the CD A developer concentration adjusting method, wherein the alkali concentration is adjusted based on a previously created relationship between an alkali concentration and a carbonate concentration capable of exhibiting a dissolving ability such that the value becomes a constant value. 2. The developer concentration control according to claim 1, wherein the alkali component of the developer is tetramethylammonium hydroxide, and the relationship between the alkali concentration and the carbonate concentration prepared in advance is represented by the following approximate expression. Method.

  When measuring the alkali concentration of the developer and the carbonate concentration in the developer, the ultrasonic wave velocity in the developer and the electromagnetic conductivity of the developer are measured as a densitometer. And a multi-component densitometer capable of detecting the alkali concentration of the developer and the carbonate concentration in the developer based on the relationship between the ultrasonic wave propagation speed and the electromagnetic conductivity at the carbonate concentration. Of adjusting the concentration of the developer.   A preparation device for preparing an alkaline developer used for developing a photoresist, a preparation tank for preparing a developer having a predetermined concentration, a supply line for supplying the prepared developer to a development process, and use A collection line for receiving the finished developer in the preparation tank, a stock solution supply line for supplying a new developer stock solution having an alkali concentration higher than a reference concentration to the preparation tank, and an alkali concentration of the developer in the preparation tank And a concentration meter for detecting 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 based on the concentration detected by the densitometer. Alkali capable of exhibiting a dissolving ability such that the alkali concentration of the developing solution measured by the densitometer and the carbonate concentration in the developing solution and the CD value obtained by the developing treatment become a constant value. Based on the previously prepared relationship between degree and carbonate concentration, the developer preparing apparatus, characterized in that has a function of adjusting the alkali concentration by controlling the supply of the developer stock solution. 5. The developing solution preparing apparatus according to claim 4, wherein the alkali component of the developing solution is tetramethylammonium hydroxide, and the relationship between the alkali concentration and the carbonate concentration prepared in advance is represented by the following approximate expression. .

  A densitometer measures the ultrasonic propagation velocity in the developer and the electromagnetic conductivity of the developer, and is based on the relationship between the ultrasonic propagation velocity and the electromagnetic conductivity at a predetermined temperature, alkali concentration and carbonate concentration prepared in advance. 6. The developing solution preparation apparatus according to claim 4 or 5, which is a multi-component concentration meter capable of detecting the alkali concentration of the developing solution and the carbonate concentration in the developing solution.   A concentration adjusting method for adjusting the alkali concentration of an alkaline developer used for developing a photoresist, measuring the alkali concentration of the developer, the carbonate concentration and the dissolved resin concentration in the developer, and developing the solution. A development characterized in that the alkali concentration is adjusted based on a pre-created relationship between an alkali concentration, a carbonate concentration, and a dissolving resin concentration that can exhibit a dissolving ability such that the CD value obtained in this way becomes a constant value. Liquid concentration adjustment method. 8. The development according to claim 7, wherein the alkali component of the developer is tetramethylammonium hydroxide, and the relationship between the alkali concentration, the carbonate concentration, and the dissolved resin concentration prepared in advance is represented by the following approximate expression. Liquid concentration adjustment method.

  In measuring the alkali concentration of developer, carbonate concentration in dissolved solution, and dissolved resin concentration, as a densitometer, the ultrasonic propagation speed in developer, electromagnetic conductivity and absorbance of developer were measured and prepared in advance. Detects alkali concentration of developer, carbonate concentration in dissolved solution, and dissolved resin concentration based on the relationship between ultrasonic wave propagation speed, electromagnetic conductivity and absorbance at a given temperature, alkali concentration, carbonate concentration and dissolved resin concentration The method for adjusting the concentration of a developer according to claim 7 or 8, wherein a possible multi-component densitometer is used.   A preparation device for preparing an alkaline developer used for developing a photoresist, a preparation tank for preparing a developer having a predetermined concentration, a supply line for supplying the prepared developer to a development process, and use A collection line for receiving the finished developer in the preparation tank, a stock solution supply line for supplying a new developer stock solution having an alkali concentration higher than a reference concentration to the preparation tank, and an alkali concentration of the developer in the preparation tank A concentration meter for detecting the carbonate concentration and dissolved resin concentration in the developer, and a control device for controlling the supply of the developer stock solution from the stock solution supply line based on the concentration detected by the densitometer, The control device is configured so that the alkali concentration of the developer measured by the densitometer, the carbonate concentration and the dissolved resin concentration in the developer, and the CD value obtained by the development processing become a constant value. It has a function of adjusting the alkali concentration by controlling the supply of the developer stock solution based on the pre-created relationship between the alkali concentration capable of exhibiting the dissolving ability, the carbonate concentration and the dissolving resin concentration. A developing solution preparation apparatus. The development according to claim 10, wherein the alkali component of the developer is tetramethylammonium hydroxide, and the relationship between the alkali concentration, the carbonate concentration, and the dissolved resin concentration prepared in advance is represented by the following approximate expression: Liquid preparation equipment.

  The densitometer measures the ultrasonic wave propagation speed in the developer, the electromagnetic conductivity and absorbance of the developer, and the ultrasonic wave propagation speed and electromagnetic conductivity at a predetermined temperature, alkali concentration, carbonate concentration, and dissolved resin concentration. The developing solution preparation apparatus according to claim 10 or 11, which is a multi-component concentration meter capable of detecting the alkali concentration of the developing solution, the carbonate concentration in the developing solution, and the dissolved resin concentration based on the relationship between the rate and the absorbance.   A developer having an alkali concentration adjusted by the developer concentration adjusting method according to any one of claims 1 to 3 and 7 to 9, using a used developer recovered from the developing process.   A developing solution prepared by using the developing solution preparation apparatus according to any one of claims 4 to 6 and 10 to 12, using a used developing solution recovered from the developing process.

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