JP6249217B2 - Resist stripper composition ratio maintaining apparatus and resist stripper composition ratio maintaining method - Google Patents

Description

  The present invention relates to a resist stripping solution composition ratio maintaining apparatus and composition ratio maintaining method used when stripping a photoresist used in photolithography, and the composition ratio of the resist stripping solution is constant over time. An apparatus and method for maintaining a composition ratio of a resist stripper that can be maintained at the same time.

  Photolithography technology is used for manufacturing semiconductors and flat displays. In photolithography, a photoresist film is formed on a substrate on which a metal film is deposited, exposed through a pattern mask, and developed. The portion of the photoresist film without the mask is softened by exposure and is removed with a developer during development. At this time, in the portion where the photoresist film having the mask is formed, the photoresist film is not dissolved and the metal film remains. Next, the substrate is etched to remove the portion of the metal film from which the photoresist film has been removed. Thereafter, the photoresist film is stripped with a resist stripping solution.

  The photoresist film that has undergone the steps of exposure and development is cured and has increased resistance to dissolution, and does not dissolve in the solution for etching the substrate. In order to peel off the photoresist film that has undergone the exposure and development steps, a dedicated resist stripping solution is used.

  Various compositions of resist stripping solutions have been proposed, but there are few resist stripping solutions composed of a single component. The resist stripping solution is a composite composition composed of a plurality of components. The resist stripping solution is spread on the substrate to be processed where the photoresist film remains in an environment of a predetermined temperature (40 ° C. to 60 ° C.). The spread resist stripping solution dissolves the photoresist film on the substrate to be processed. And it collect | recovers with this melt | dissolved resist component and uses again through a filtration means. That is, the resist stripping solution is circulated and used.

  Since the resist stripping solution is formed of a plurality of components, there is an allowable range in the composition ratio of each component for producing the effect of stripping the photoresist film. The permissible width refers to the width of the composition ratio that can be determined to have performance as a resist stripping solution even if the composition ratio of each component is shifted. That is, if the composition ratio is within the allowable range, it can be used as a resist stripping solution. However, if the composition ratio deviates from the allowable range, it cannot be used as a resist stripping solution.

  In the step of resist stripping, there is a resist stripping solution taken out of the apparatus together with the substrate to be processed. Further, each component is lost by evaporation in an environment where the resist stripping solution is used. In general, the amount taken out together with the substrate or lost by evaporation is not the same ratio for each component. As a result, the composition ratio of the resist stripping solution changes with the substrate processing and the passage of time. If left as it is, the composition ratio deviates from the allowable range, and the resist stripping solution causes a problem that the photoresist film cannot be stripped or even corrodes the underlying metal film.

  For this problem, in Patent Document 1, a stock solution of a resist stripping solution is prepared in advance. Then, the water content in the resist stripping solution is measured, and the performance of the resist stripping solution is maintained by replenishing the stock solution and water appropriately.

Japanese Patent No. 3093975 (Japanese Patent Laid-Open No. 10-022261)

  The resist stripping solution is a mixed solution of a plurality of solutions. If the same mixed solution is circulated for a long time, the composition ratio deviates from the composition ratio of a predetermined allowable width, and the resist stripping performance changes. For example, moisture is evaporated in a high temperature environment in the peeling process, and the pH of the mixed solution is lowered due to dissolution of the resist component, leading to a reduction in peeling performance. Therefore, the resist component dissolved when the mixed solution is taken out to the substrate to be processed adheres to the substrate to be processed, causing a circuit stacking fault on the substrate to be processed, and the yield is deteriorated.

  Therefore, when the resist stripping solution is continuously used for a long time, there is a problem that the ratio of the mixed component deviates from the allowable width value. This occurs because each component including the moisture of the resist stripping solution in the stripping apparatus changes little by little due to evaporation due to a difference in vapor pressure at the atmosphere and in the tank temperature. In addition, as the resist stripping process proceeds, other components contained in the resist, the substrate, and the like are dissolved, resulting in a decrease in the effective component concentration of the resist stripping solution.

  In Patent Document 1, since a stock solution of resist stripping solution is prepared and prepared, a stock solution or water in which each component is mixed at a predetermined ratio is replenished, but a shortage for each component is replenished or water is added. It is not possible to supply a mixed solution containing the composition so that each component of the resist stripping solution is within the allowable range.

  It is considered that the resist stripping performance can be maintained even by the method of Patent Document 1 as long as the resist stripping performance does not have a great difference in performance even if each component of the resist stripping solution changes. However, if there is a change in the resist stripping performance even with a slight change in each component, it is necessary to keep it within an allowable range by some method.

  Further, the resist stripping solution is mainly composed of an organic solvent and water. Many organic solvents used have a boiling point higher than that of water. Further, the alkaline organic solvent component has the effect of stripping the photoresist. Further, not only evaporation but also carry-out does not occur uniformly for each component. Therefore, the concentration change of the organic solvent component cannot be managed only by the concentration change of water. The concentration of the organic solvent component must be directly grasped and the concentration change must be corrected. That is, as in Patent Document 1, if the concentration of water is measured, the composition ratio of the resist stripping solution cannot be maintained.

  The present invention has been conceived in view of the above problems, and measures the change in the composition ratio of the resist stripping solution (concentration of each component), and the resist stripping solution concentration so that the composition ratio of each component is constant Adjust. In other words, in order to prevent the concentration of the resist stripping solution from falling within the allowable range, the resist stripping solution composition ratio maintaining device for replenishing insufficient chemicals and moisture, and the method of maintaining the resist stripping solution composition ratio within the allowable range I will provide a.

More specifically, the resist stripping solution composition ratio maintaining apparatus according to the present invention is:
A management tank that is used in circulation and stores a resist stripper composed of a plurality of components including an organic solvent and water,
A first load cell for measuring the weight of the resist stripping solution in the management tank;
A first concentration measuring device for measuring the concentration of the plurality of components in the resist stripping solution;
If any of the plurality of components is out of a predetermined range, the composition ratio of the plurality of components is set to the predetermined range based on the concentration of the plurality of components and the weight of the resist stripping solution. A controller for calculating amounts of the plurality of components constituting a replenishing solution for correction to
A blending tank in which the calculated amount of the plurality of ingredients is charged and the replenisher solution is blended;
It has the liquid feeding means which sends the said replenishment solution from the said preparation tank to the said management tank, It is characterized by the above-mentioned.

Moreover, the composition ratio maintaining method of the resist stripper according to the present invention is as follows:
Circulating and measuring the weight of the resist stripping solution in a management tank in which a resist stripping solution comprising a plurality of components including an organic solvent and water is stored;
Measuring the plurality of component concentrations in the resist stripping solution;
If any of the plurality of components is out of a predetermined range, the composition ratio of the plurality of components is set to the predetermined range based on the concentration of the plurality of components and the weight of the resist stripping solution. Calculating the amount of the plurality of components constituting the replenishing solution for correction to
Mixing the calculated amount of the plurality of ingredients to prepare the replenishing solution;
It has the process of sending the said replenishment solution to the said control tank.

  The present invention calculates the composition of a replenishing solution for correcting the composition ratio of the resist stripping solution to a predetermined range when the concentration of any component in the resist stripping solution is out of the predetermined range, Since the replenishment is performed, the concentration of each component of the resist stripping solution can be prevented from deviating from the allowable range. Therefore, when it is feared that the resist stripping performance is lowered due to a change in the concentration of each component, the resist stripping performance can be kept constant.

  Moreover, since the shortage amount of each component is added to the resist stripping solution after blending separately in the blending tank, the concentration of the resist stripping solution being circulated does not change abruptly. Therefore, the resist stripping operation can be performed while replenishing the shortage.

  Further, since the replenishing solution to be replenished is measured by the load cell, it can be weighed in large quantities and accurately. Further, a replenishment solution is prepared, the concentration of each component that changes during the work time until the liquid feeding is completed is estimated, and replenishment is performed in anticipation of the estimated concentration change. Therefore, even during the preparation of the replenishing solution, the composition ratio of the resist stripping solution can be prevented from deviating from the allowable range.

It is a figure which shows the structure of the composition ratio maintenance apparatus of the resist stripping solution which concerns on this invention. It is a graph which shows the relationship between the resist component density | concentration in resist stripping solution, and time. It is a graph which shows the relationship between the component density | concentration in a resist stripping solution, and time. It is a figure which shows the operation | movement flow of the composition ratio maintenance apparatus of the resist stripping solution which concerns on this invention. It is a graph explaining the estimation of each component density | concentration of the resist stripping solution in the time which prepared the replenishment solution and finished liquid feeding. It is a graph which shows the relationship between the component density | concentration in resist stripping solution, and the time after density | concentration correction.

  The resist stripping solution composition ratio maintaining apparatus 1 according to the present invention will be described below with reference to the drawings. The following description is an example of one embodiment of the present invention, and the present invention is not limited to the following description. The following embodiments can be modified without departing from the spirit of the present invention.

  FIG. 1 illustrates the configuration of a resist stripping solution composition maintaining apparatus 1 according to the present invention. The resist stripping solution composition ratio maintaining apparatus 1 according to the present invention includes a management tank 10, a preparation tank 20, and a controller 60. In addition, the management tank 10 and the mixing tank 20 are respectively provided with load cells 42 and 41 between the supports 25 and 21, and are arranged at positions where the liquid weight in the management tank 10 and the mixing tank 20 can be measured. Yes.

  A shower unit 18 is disposed in the upper part of the management tank 10. A substrate transfer means 16 is disposed between the management tank 10 and the shower unit 18. The substrate transfer means 16 conveys the substrate 9 to be processed coated with a resist to be peeled off. Specifically, a belt conveyor, a roller conveyor, etc. can be used suitably.

  One end of a pipe L <b> 24 is connected to the bottom of the management tank 10 and extends to the shower unit 18. A valve V24 is provided in the pipe L24. The shower part 18 is an apparatus which sprays the solution in the management tank 10 which has been sent by the pipe L24 in a state suitable for removing the resist. A filter F24 and a pump 56 are disposed in the pipe L24.

  A pipe L <b> 26 is installed from the bottom of the management tank 10 to the top of the management tank 10 for circulating the resist stripping solution in the management tank 10. A pump 58 is provided in the pipe L26. Further, the filter F26 is disposed in front of the discharge port of the pipe L26. This is to prevent cavitation, which is an adverse effect on the pump 58 due to adhesion, accumulation, clogging, etc., to the piping due to resist components mixed in the circulating resist stripping solution.

  A concentration measuring device 44 is also provided in the pipe L26. It is desirable that the concentration measuring device 44 can measure the concentration of a plurality of components. An absorptiometer, an IR measuring instrument, an ultrasonic measuring instrument, etc. can be used suitably.

  A pipe L50 is connected to the bottom of the management tank 10 for disposal of the resist stripping solution. The pipe L50 is provided with a valve V50.

  The blending tank 20 has one end of a pipe L23 connected to the bottom. The other end of the pipe L23 is in communication with the management tank 10. The pipe L23 is provided with a pump 54 and a filter F23.

  A valve V23 is also arranged in the middle of the pipe L23. One end of a pipe L22 is connected to the branch port of the valve V23. The other end of the pipe L22 communicates with the charging port of the preparation tank 20. The pipe L22 is also provided with a pump 52 and a concentration measuring device 43. The concentration measuring device 43 may be the same as the concentration measuring device 44.

  A first solution tank 31, a second solution tank 32, and a third solution tank 33 that store respective components of the resist stripping solution are communicated with the preparation tank 20. In the present embodiment, there are three solution tanks, but the number of solution tanks is not particularly limited to three. Each solution tank communicates with the preparation tank 20 through pipes L31, L32, and L33. Valves V31, V32, and V33 are arranged in each pipe.

  Further, a standard stripping solution tank 30 for storing the standard stripping solution is communicated with the management tank 10 via a pipe L30. A valve V30 is disposed in the pipe L30. Here, the standard stripping solution is a solution mixed at the most desirable composition ratio (composition ratio) of the resist stripping solution.

  As the controller 60, a computer including an MPU (Micro Processor Unit) and a memory can be suitably used. The controller 60 can receive at least signals from the concentration measuring devices 43 and 44 and the load cells 41 and 42, and can transmit an instruction signal for controlling opening and closing to the valves V30, V31, V32, and V33. The pumps 52, 54, 56 and 58 and the valves V23, V24 and V50 may be controlled. In FIG. 1, a signal line transmitted from the controller 60 is indicated by a one-dot chain line, and a signal received by the controller 60 is indicated by a dotted line.

  Next, the operation of the resist stripping solution composition ratio maintaining apparatus 1 will be described. In the management tank 10, a resist stripping solution is stored. The resist stripping solution is sent through the pipe L24 to the shower unit 18 by the pump 56, and is spread on the substrate 9 to be processed on the substrate transfer means 16. And it returns in the management tank 10 with the peeled resist component. That is, the resist stripping solution is circulated.

  Since the resist component peeled from the substrate 9 to be processed accumulates in the management tank 10, the concentration of the resist component in the resist stripping solution used in circulation increases with time. The graph of FIG. 2 schematically represents this state. The horizontal axis is time, and the vertical axis is the resist component concentration.

  As the resist component concentration increases, the filter F24 increases small debris that cannot be eliminated and remains on the substrate 9 to be processed. Such residual debris is not preferable because it causes pinholes and defective laminated circuits in the subsequent film formation process. Therefore, when the resist component concentration exceeds the predetermined value Cqth, the resist stripping solution itself must be replaced. FIG. 2 shows that the resist stripping solution is replaced at A (for example, when the resist component in the management tank 10 reaches 2000 ppm).

  By the way, the substrate to be processed 9 is passed through the shower of the resist stripping solution by the substrate transfer means 16 so that the photoresist is stripped. At this time, some resist stripping solution is taken out of the management tank 10 together with the substrate 9 to be processed.

  Further, in order to enhance the resist peeling effect, the shower unit 18 and the management tank 10 are installed in an environment having a predetermined temperature. For example, the environment is 40 ° C to 60 ° C. The components in the resist stripper do not boil at this temperature. However, the evaporation of each component cannot be prevented. Then, the component concentration of the resist stripping solution changes until time A in FIG. 2 in which the resist stripping solution is replaced.

  The resist stripping solution is a mixed solution of a plurality of solutions, and the resist stripping performance changes when the composition ratio deviates from a predetermined composition ratio. If the resist stripping performance is insufficient, the resist film may be peeled off due to a remaining photoresist film or the like formed on the upper surface of the removed photoresist layer. Further, if the lower layer is peeled off or corroded, a conduction failure will occur. In any case, if the resist stripping performance changes, there is a high possibility that it will lead to product defects.

  Therefore, it is necessary to maintain the composition ratio of the resist stripping solution within the allowable range even during the period B in FIG. The “allowable width” is the width of the concentration of each component that can exert the effect as a resist stripping solution. The ratio of the concentration of each component is the composition ratio. Therefore, the allowable width may be said to be the width of the composition ratio.

  The resist stripping solution composition ratio maintaining apparatus 1 corrects such a change in the composition of the resist stripping solution. That is, when the composition ratio of the resist stripping solution is shifted, a part of the resist stripping solution in the management tank 10 is discarded and a separately prepared replenishing solution is added to correct the shift in the composition ratio. This may be said to be a deviation in the concentration of each component, or a composition ratio of the resist stripping solution to be corrected or a concentration adjustment. Conventionally, individual components are not managed in this way, and the concentration is adjusted by adding water or stripping solution. Therefore, the individual component concentrations of the resist stripping solution in the management tank in use may fall outside the allowable range. It was. The resist stripping solution composition ratio maintaining apparatus 1 according to the present invention performs management so that the concentration of the individual components of the resist stripping solution does not deviate from the allowable range.

  FIG. 3 shows an example of changes in the concentration of each component of the resist stripping solution. The horizontal axis is time, and the vertical axis is the concentration of each component. In order to simplify the explanation, it is assumed that the resist stripping solution is composed of component a, component b and water. Components a and b are organic solvents. Of course, the components of the resist stripping solution of the present invention are not limited to three. Component a, component b, and water are stored in solution tanks 31, 32, and 33 in FIG.

  When the resist stripping solution composition ratio maintaining apparatus 1 is started, it is assumed that the management tank 10 is filled with a resist stripping solution in which components are mixed at an optimal composition ratio. Note that desirable concentrations (hereinafter referred to as “specified concentrations”) of the respective components are Cfa, Cfb, and Cfw. In FIG. 3, it is shown by a one-dot chain line. The state in which each component is mixed at a specified concentration is called a “specified composition ratio”.

  In the resist stripping solution, an upper limit value and a lower limit value of a concentration range in which it is not necessary to adjust the concentration of each component are determined. That is, if the concentration of each component is within this range, it is not necessary to adjust the concentration of the resist stripping solution. However, if any component concentration is out of this range, the concentration is adjusted.

  The range between the upper limit value and the lower limit value is set narrower than the upper limit value and the lower limit value of the allowable range. The reason why the density adjustment is started after the allowable width is exceeded is that the photoresist is peeled off with the resist stripping solution outside the allowable width. Further, the upper limit value and the lower limit value are set so that the concentration adjustment of the resist stripping solution can be made in time even if a replenishment solution for concentration adjustment is prepared after deviating from this range.

  That is, the upper limit value and the lower limit value are determined in consideration of the concentration change rate of the resist stripping solution and the time lag for preparing the concentration adjusting replenisher solution. Such a range between the upper limit value and the lower limit value is defined as an “operation allowable range”. Therefore, in other words, an allowable operating range is set as a reference for determining whether or not to perform density adjustment for each component.

  Let the upper limit value and the lower limit value of the operation allowable width of each component (component a, component b, water) be CaH, CaL, CbH, CbL, CwH, and CwL, respectively. Assuming that the concentration of each component is Cqa, Cqb, and Cqw, the range of each component is expressed as in equation (1), equation (2), and equation (3).

CaL ≦ Cqa ≦ CaH (1)

CbL ≦ Cqb ≦ CbH (2)

CwL ≦ Cqw ≦ CwH (3)

  The specified concentrations (Cfa, Cfb, Cfw) are between the upper limit value and the lower limit value, but are not necessarily in the center between the upper limit value and the lower limit value. Moreover, in FIG. 3, the upper limit value and the lower limit value of the operation allowable width of each component are indicated by a two-dot chain line.

  Each component of the resist stripping solution is lost due to removal and evaporation due to use, and the composition ratio changes every moment. In FIG. 3, it is assumed that the amount of water lost is the largest due to evaporation and takeout, the amount of loss of component b is next, and the amount of loss of component a is the smallest. In such a case, the moisture concentration decreases with time. On the other hand, the concentrations of component a and component b gradually increase. This is because even at the same time, the rate of water loss is less than the rate of water loss.

  In addition, since the resist stripping solution is circulated and used, the resist resin to be stripped (novolak resin) is mixed in the stripping solution as indenecarboxylic acid, so that the pH value of the stripping solution is lowered and the resist stripping performance is improved. descend. Therefore, the component concentration of the resist stripping liquid in the management tank 10 is monitored and measured, and when the concentration of any of the components deviates from the operation allowable range, the concentration is maintained at a predetermined concentration (concentration within the operation allowable range). It is necessary to.

  The resist stripping solution composition ratio maintaining device 1 monitors the concentration of the resist stripping solution in the management tank 10 and prepares a replenishing solution for concentration adjustment when the concentration of any of the components deviates from the allowable operating range. And added to the management tank 10. That is, by adding the replenisher solution, the concentration of the resist stripping solution in the management tank 10 is maintained at a predetermined concentration.

  Note that the resist stripping solution in the management tank 10 may be added with a standard stripping solution to compensate for a slight loss if the concentration of each component is within the allowable operating range. The standard stripping solution is a resist stripping solution in which each component is mixed at a specified concentration. In order to maintain the resist stripping solution in the management tank 10 at a constant amount, when a small amount of the standard stripping solution is always supplied, as shown by the circled portion in FIG. There is a slight concentration recovery. Accordingly, when viewed in detail, the concentration of the component a gradually increases while going up and down. However, the supply of the standard stripping solution cannot stop the change in the concentration of each component. If it sees largely, as shown in FIG. 3, the density | concentration of each component will leave | separate from a regulation density gradually.

  Next, a specific method for maintaining the composition ratio will be described. First, the amount of the resist stripping solution in the management tank 10 is set to Wmx. The preparation amount Wmx is the weight of the resist stripping solution in a state where the component a, the component b, and water are mixed so as to have a specified concentration ratio (specified composition ratio). And let the minimum liquid quantity which can operate the management tank 10 be Wu. The minimum operable liquid amount Wu refers to the minimum amount of liquid that can operate the shower unit 18 to remove the photoresist from the substrate 9 to be processed.

  Moreover, let the preparation amount of the preparation tank 20 be Mm. This is the total weight of the replenishment solution that can be prepared in the preparation tank 20 and sent to the management tank 10. Accordingly, during mixing, the amount remaining in the pipe for mixing and circulation (L22 in FIG. 1) and the loss of the replenishing solution remaining in the pipe from the mixing tank 20 to the management tank 10 (L23 in FIG. 1) It is decided in consideration of minutes. The total weight Mm of the replenishing solution is set to an amount obtained by subtracting the minimum operable liquid amount Wu from the charged amount Wmx (Mm = Wmx−Wu), excluding the loss. That is, the concentration adjustment is performed with the amount (Wmx−Wu) of the resist stripping solution Wmx in the management tank 10 discarded to the minimum operable liquid amount Wu.

  FIG. 4 shows a processing flow of the controller 60 according to the present invention. When the controller 60 starts the process (step S100), it makes an end determination (step S102). Here, the end determination may be based on the determination that the concentration of the resist component in the resist stripper exceeds a predetermined concentration (such as Cqth described in FIG. 2). In addition, an operator's request for an emergency stop or the like may be determined as termination.

  When the process ends (Y branch in step S102), the resist stripping solution composition ratio maintaining apparatus 1 itself is stopped (step S200). In addition, when the density | concentration of the resist component in resist stripping solution exceeds predetermined density | concentrations (Cqth etc.), you may perform the process (it does not describe) which replaces the resist stripping liquid in the management tank 10 entirely.

  When the process is continued (N branch in step S102), the resist stripping solution weight Wm in the management tank 10 and the concentrations Cqa and Cqb of the components a and b are measured by the load cell 42 and the concentration measuring device 44 (step). S104). The water concentration Cqw can be obtained by subtracting the concentration Cqa of the component a and the concentration Cqb of the component b from 100% (total concentration).

  The reason why the water concentration Cqw is not directly measured is that it is important to accurately measure the concentration of other components (organic solvent) having a resist stripping effect. Another component (organic solvent) is more affected by the concentration change. However, the present invention does not exclude measuring the concentration of water.

  Next, it is checked whether or not the concentrations of component a, component b and water are included in the “operation allowable range” (step S106). When the concentration value measured in step S104 exceeds the permissible range, the replenishing solution is prepared and added. If the product manufactured in the meantime, the resist stripping performance is insufficient or the base layer is stripped too much. May corrode. Therefore, the replenisher solution must be prepared before the concentration of each component exceeds the allowable range. That is, the operation allowable width is set in a range narrower than the allowable width.

  If each component is within the allowable operating range (Y branch in step S106), it is determined whether or not the decrease amount δW of the weight of the resist stripping solution in the management tank 10 is equal to or greater than a predetermined threshold value Thw. (Step S107). The reduction amount δW is represented by a difference (Wmx−Wm) between the weight Wm of the resist stripping solution in the management tank 10 measured in step S104 and the preparation amount Wmx in the management tank 10.

  When the decrease amount δW is larger than the predetermined threshold value Thw (Y branch of step S107), the standard stripping solution corresponding to the decrease amount δW is added to the management tank 10 from the standard stripping solution supply means (step S108). That is, the weight of the resist stripping solution in the management tank 10 is controlled so as to always be the charged amount Wmx. Note that step S107 and step S108 may be omitted. The standard stripping solution supply means includes a standard stripping solution tank 30, a pipe L30 to the management tank 10, and a valve V30 provided in the pipe L30. Further, the controller 60 may be added to open / close the valve V30.

  The flow of post-processing in step S108 returns to step S102, and after step determination (step S102), step S104 is repeated again. If the reduction amount δW of the resist stripping solution in the management tank 10 is smaller than the predetermined threshold value Thw in step S107 (N branch of step S107), the process returns to step S102 as it is, and the end determination (step S102) and subsequent steps are repeated. Note that the resist stripping solution weight Wm and the component concentrations Cqa, Cqb, and Cqw measured and calculated in step S104 are recorded in the controller 60 sequentially.

  Returning to step S106, if any of the components of the resist stripping solution in the management tank 10 deviates from the relationship of equations (1) to (3) (N branch in step S106), the replenisher solution is added. Move on to processing.

  First, the weight of each component constituting the replenishing solution is calculated. For this purpose, first, the concentration of each component after “working time Ts” is estimated (step S110). “Working time Ts” is the time for the controller 60 to calculate the amount of replenishment solution, actually prepare the replenishment solution in the preparation tank 20, and send it to the management tank 10. A disposal time for discarding the resist stripping solution in the management tank 10 may be added.

  The calculation of the weight of each component of the replenishment solution in the controller 60 can be obtained in a very short time by building a program in advance. However, in order to actually prepare the replenisher solution in the preparation tank 20, each component must be added to the preparation tank 20 while being weighed. Moreover, also about the liquid feeding from the preparation tank 20 to the management tank 10, you have to send the prepared replenishment solution of total weight Mm using piping. Then, a time lag occurs from the start of the preparation of the replenishment solution until the replenishment solution is actually sent to the management tank 10.

  Even during this time lag, the deviation of the composition ratio proceeds. In particular, in a resist stripping apparatus that handles a large substrate 9 to be processed, a large amount of resist stripping solution is lost per unit time, and it takes time to prepare a replenishing solution. Therefore, even if the weight of each component of the replenishing solution for correcting the composition ratio of the resist stripping solution at the time when the processing shifts to the N branch in step S106 is calculated and sent to the management tank 10, the replenishing solution actually When the liquid is fed to the management tank 10, the composition ratio cannot be corrected correctly. This is because when the supply of the replenisher solution to the management tank 10 is started, the composition ratio of the resist stripping solution is deviated from that determined when the composition ratio is corrected in step S106. This time lag is defined as a work time Ts.

  The work time Ts may be a predetermined time. This is because the time for preparing the replenishment solution having the total weight Mm and the time for feeding it to the management tank 10 can be determined in advance by measurement or calculation.

  The estimation of the concentration of each component after the working time Ts may be obtained by extrapolating the temporal change of each component weight obtained from the resist stripping solution weight Wm and the component concentrations Cqa and Cqb measured in step S104. . Various functions may be used for extrapolation. Here, for the sake of simplicity, extrapolation is performed using a linear function.

  FIG. 5 is a graph showing how the concentration fluctuation of each component is estimated at this time. FIG. 5 is an enlarged view around time T1 in FIG. In FIG. 5, the horizontal axis represents time. The vertical axis represents the concentration of each component. About component a, the upper limit CaH vicinity of the driving | operation tolerance width is shown. The arrow “N” on the horizontal axis indicates the time (current time T1) at which the replenisher solution is determined in step S106. Also, an arrow “F” indicates a time (scheduled time T2) after the work time Ts from the arrow “N”. The scheduled time T2 is the time when the replenishment solution starts to be fed to the management tank 10. If the component a exceeds the upper limit CaH of the allowable driving range at the current time T1, the process flow moves to the N branch in step S106 in FIG. 4 at the current time T1.

  The data on the left side of the arrow “N” is obtained by connecting the actual measured values so far with a straight line. The right side from the arrow “N” is a straight line obtained by extrapolating the straight line. In addition, when the actual measurement value is changing while repeating the up and down movement as shown by a circled portion in FIG. 3, extrapolation may be performed using the least square method. The extrapolated part is represented by a dotted line. The reason for the straight line is that a linear function is used. Then, the concentrations of the component a, the component b, and the component w at the time (scheduled time T2) after the working time Ts from the current time T1 are assumed to be estimated concentrations ACa, ACb, and ACw, respectively. These values are the estimated concentrations of each component after the working time Ts in step S110.

  Referring to FIG. 4 again, next, in step S112, the total weight Mm of the replenishing solution is calculated based on the estimated concentration at the scheduled time. In this step, if the total amount of the replenisher solution is Mm and the composition ratio of the resist stripping solution in the management tank 10 when the replenisher solution is added falls within the allowable operating range, the total weight Mm of the replenisher solution is The calculation may be performed by any method. For example, an example is shown below.

  The weights of component a, component b, and water in the replenishing solution are Ma, Mb, and Mw. The total weight Mm of the replenishing solution is expressed by the following equation (4).

Mm = Ma + Mb + Mw (4)

  Since the total weight Mm of the replenishment solution is the difference between the charged amount Wmx of the management tank 10 and the minimum operable liquid amount Wu, it can be obtained as shown in equation (5) as already described.

Mm = Wmx-Wu (5)

  The estimated concentration of the estimated component a was ACa. Therefore, the concentration of the component a at the scheduled time when the replenishment solution is added is expressed as (ACa × Wu + Ma) / Wmx. If this concentration is the specified composition ratio Cfa of component a, the following equation (6) is established.

(ACa × Wu + Ma) / Wmx = Cfa (6)

  From this, the weight Ma of the component a of the replenishing solution can be obtained by the following equation (7).

Ma = Wmx × Cfa−ACa × Wu (7)

  The weight Ma of the component a can be said to be an insufficient amount from the specified weight (Wmx × Cfa) of the component a at the scheduled time. The specified weight refers to the weight of each component (here component a) in the standard stripping solution charge.

  Similarly, the component b of the replenishing solution and the weights Mb and Mw of water can be obtained by the following equations (8) and (9).

Mb = Wmx × Cfb−ACb × Wu (8)

Mw = Wmx × Cfw−ACw × Wu (9)

  When the component weights Ma, Mb, and Mw of the replenishing solution are obtained in step S112, the replenishing solution is prepared in the preparation tank 20 (step S114). The replenishment solution is prepared by sequentially adding each component to the preparation tank 20 while measuring the weight. At this time, it is desirable that the inside of the preparation tank 20 be sufficiently circulated and stirred by the pipe L22 and the pump 52. Further, after all the components are charged into the preparation tank 20, a step of measuring the concentration of each component with the concentration measuring device 43 and confirming the input amount of each component from the total weight Mm may be included.

  When the preparation of the replenishing solution is completed, the resist stripping solution in the management tank 10 is discarded up to the minimum operable liquid amount Wu (step S116). This step may be performed simultaneously with the preparation of the replenishing solution (step S114). When the resist stripping solution in the management tank 10 is discarded to the minimum operable liquid amount Wu, the replenishment solution is sent to the management tank 10 (step S118). The replenishment solution is sent by the pump 54 through the pipe L23 by connecting the valve V23 to the management tank 10 side. The valve V23, the pipe L23, and the pump 54 constitute liquid feeding means.

  By feeding the replenisher solution, the resist stripping solution in the management tank 10 is maintained at a substantially specified composition ratio. In the graph of FIG. 5, point F is the time (scheduled time T2) at which the replenisher solution was added, and indicates that the concentration of each component has been recovered to the specified concentration at time T3. The specified concentration Cfa of the component a has deviated from the graph range. Then, the flow of the controller 60 returns to step S102 again.

  By passing through the above processes, the resist stripping solution in the management tank 10 can maintain a constant composition ratio.

  In the resist stripping solution composition ratio maintaining apparatus and method according to the present invention, the replenishing solution is always prepared by calculating the corrected concentration from the current concentration in the management tank 10. At this time, if it is found that even if the replenisher solution is added, the concentration recovery effect of any component is not effective, or the concentration of any component does not reach the target value, the “concentration control impossible” or You may make it notify of "exchange to a new liquid". Such processing can be performed in step S110.

  Also, here, “no effect of concentration recovery of any component” means that the concentration of that component has changed in the vicinity of the upper limit or lower limit of the allowable operating range, and it is necessary to adjust the concentration next. This includes cases where there is very little time until the scheduled time.

  In the above description, the composition ratio of the resist stripping solution is corrected to the specified composition ratio by the replenishing solution. However, the composition ratio of the resist stripping solution is not limited to the correction to the specified composition ratio. In the present invention, the composition ratio of the resist stripping solution may be corrected to at least the allowable operating range. An example is shown in FIG.

  FIG. 6 is a view similar to FIG. 3, but the composition ratio of the resist stripping solution at time T3 is different. In FIG. 3, the composition ratio has returned to the prescribed composition ratio (the concentrations of the components are the prescribed concentrations Cfa, Cfb, and Cfw). On the other hand, in FIG. 6, at time T3, the concentration of component a is lowered to the lower limit value CaL of the allowable operating range, component b is set to a concentration lower than the specified concentration Cfb, and water is corrected to the specified concentration Cfw. I made it.

  This is because the change in the concentration of the component a is greater than the change in the concentration of the component b and water, and therefore the concentration of the component a is corrected in the opposite direction to the change. By doing in this way, there exists an effect that time to the next density adjustment can be lengthened. Moreover, even when the loss rate of each component changes for some reason during use, it can respond flexibly, and the composition ratio of the resist stripping solution can be maintained within an allowable range.

  As described above, in the present invention, the corrected concentration of each component may be set anywhere as long as it is within the allowable operating range. That is, in the present invention, when any component is out of a predetermined range, the composition ratio of the plurality of components can be corrected to any concentration in the predetermined range.

  In order to do this, in the equation (6), the right side is expressed as an arbitrary point (concentration) pH within the allowable operating range.

(ACa × Wu + Ma) / Wmx = Cta (10)

  The weight Ma of the component a of the replenishing solution obtained by the formula (10) is expressed as the formula (11). Similarly, the concentrations to be set for the component b and the amount of water (Mb, Mw) are respectively expressed as equations (12) and (13), where Ctb and Ctw are respectively set.

Ma = Wmx × Cta−ACa × Wu (11)

Mb = Wmx × Ctb−ACb × Wu (12)

Mw = Wmx × Ctw−ACw × Wu (13)

  The resist stripping solution composition ratio maintaining apparatus according to the present invention can be used not only for resist stripping but also as an etching apparatus for performing photolithography.

DESCRIPTION OF SYMBOLS 1 Resist stripping liquid composition ratio maintenance apparatus 9 Processed substrate 10 Management tank 16 Substrate transfer means 18 Shower part 20 Preparation tank 25, 21 Support body 30 Standard stripping liquid tank 31 1st solution tank 32 2nd solution tank 33 3rd solution Tanks 42, 41 Load cells 43, 44 Concentration measuring device 60 Controllers L22, L23, L24, L26, L30, L31, L32, L33, L50 Piping V23, V24, V30, V31, V32, V33, V50 Valves F23, F24, F26 Filter 52, 54, 56, 58 Pump

Claims (7)

A management tank that is used in circulation and stores a resist stripper composed of a plurality of components including an organic solvent and water,
A first load cell for measuring the weight of the resist stripping solution in the management tank;
A first concentration measuring device for measuring the concentration of the plurality of components in the resist stripping solution;
If any of the plurality of components is out of a predetermined range, the composition ratio of the plurality of components is set to the predetermined range based on the concentration of the plurality of components and the weight of the resist stripping solution. A controller for calculating amounts of the plurality of components constituting a replenishing solution for correction to
A blending tank in which the calculated amount of the plurality of ingredients is charged and the replenisher solution is blended;
An apparatus for maintaining a composition ratio of a resist stripping solution, comprising liquid feeding means for feeding the replenisher solution from the preparation tank to the management tank.   2. The resist stripping solution composition ratio maintaining apparatus according to claim 1, wherein the controller obtains the concentration of water by subtracting the total concentration of components other than water from the total concentration.   The controller calculates an estimated concentration of each component after a working time necessary for preparation of the replenishing solution and feeding of the replenishing solution, and corrects the resist stripping solution having the estimated concentration to a specified composition ratio. 3. The resist stripping solution composition ratio maintaining apparatus according to claim 1, wherein the amount of the plurality of components constituting the replenishing solution is calculated.   The composition ratio maintenance of the resist stripping solution according to any one of claims 1 to 3, further comprising a second concentration measuring device for measuring the concentration of the organic solvent in the replenishing solution. apparatus. Circulating and measuring the weight of the resist stripping solution in a management tank in which a resist stripping solution comprising a plurality of components including an organic solvent and water is stored;
Measuring the plurality of component concentrations in the resist stripping solution;
If any of the plurality of components is out of a predetermined range, the composition ratio of the plurality of components is set to the predetermined range based on the concentration of the plurality of components and the weight of the resist stripping solution. Calculating the amount of the plurality of components constituting the replenishing solution for correction to
Mixing the calculated amount of the plurality of ingredients to prepare the replenishing solution;
A method of maintaining a composition ratio of a resist stripping solution, comprising a step of feeding the replenishing solution to the management tank.   6. The method of maintaining a composition ratio of a resist stripping solution according to claim 5, wherein the concentration of water is obtained by subtracting the total concentration of components other than water from the total concentration.   The step of calculating the amount of the plurality of components constituting the replenishing solution calculates the estimated concentration of each component after the working time necessary for the preparation of the replenishing solution and the feeding of the replenishing solution, and the estimated concentration 7. The method according to claim 5, wherein the amount of the plurality of components constituting the replenishing solution for correcting the resist stripping solution to a specified composition ratio is calculated. A method for maintaining the composition ratio of the resist stripping solution.