TWI697743B - Photoresist component concentration measuring device and concentration measuring method - Google Patents

Abstract

The recycled photoresist stripping solution often denatures as the dissolved photoresist increases. Therefore, when the absorbance is used for concentration measurement, there is a problem of calibration curve shift.

The present invention is a photoresist component concentration measuring device, which is characterized in that it includes a measuring means, which can select an element that contains a photoresist but does not contain the photoresist stripping stock solution, and measures the selected specific element in Concentration in photoresist stripping solution.

Description

Photoresist component concentration measuring device and concentration measuring method

The present invention relates to a photoresist component concentration measuring device and a concentration measuring method, which can measure the photoresist concentration in a photoresist stripper used in photolithography technology.

In devices such as integrated circuits (IC) and large integrated circuits (LSI), with the increase in the integration of semiconductor elements and the shrinking of the size of wafers, wiring circuits are also developing towards miniaturization and multilayering. Furthermore, not only such tiny components, but also in flat panel displays (FPDs) such as liquid crystal screens, in order to form pixels, tiny wiring circuits are required. In order to make such a tiny wiring circuit, photolithography technology is required.

In photolithography, a thin film of material used to make wiring circuits is formed, and photoresist is coated on the thin film. Then, after the photoresist is exposed to the pattern corresponding to the wiring and removed, the material film is etched. Finally, remove the photoresist. As for the positive photoresist, in order to remove the photosensitive photoresist, a photoresist stripper is used.

The photoresist stripper can be used repeatedly to some extent, so the concentration of the photoresist will gradually increase. Repeated use of photoresist stripping solution can cause economic problems. Moreover, when the concentration of the photoresist increases to a certain level, stopping the use may cause quality problems in the product.

In other words, when the photoresist stripping solution is half used, it is necessary to monitor the photoresist concentration, and once it reaches a predetermined concentration or higher, replace all or part of it.

There are several methods to consider for the determination of the photoresist concentration in the photoresist stripping solution. In factories that perform mass production, a method that can determine the photoresist concentration with a certain degree of accuracy in a short time is required.

Patent Document 1 discloses a method for obtaining the photoresist concentration in the photoresist stripping solution from the absorbance. In this method, the phenomenon that the higher the concentration of the photoresist in the photoresist stripping solution, the higher the absorbance is used. In other words, the absorbance of the photoresist stripping liquid at which the concentration of the photoresist is known is obtained in advance, and this is used as a calibration curve to determine the concentration of the photoresist.

However, in the concentration measurement determined based on the absorbance, even if the photoresist concentration is fixed, there is a problem that the absorbance in the photoresist stripping solution changes with time. It is presumed that the reason is that the photoresist dissolved in the photoresist stripping solution is slowly decomposed into low molecules, so that the peak of the absorption spectrum is converted to the low wavelength side.

In addition, in concentration measurement determined based on absorbance, temperature management of the object to be measured becomes important.

In the actual manufacturing process, it will take several weeks to replenish the photoresist stripper while continuing production. In other words, the decomposition components of the photoresist that has various absorption spectra and have been dissolved will be mixed in the photoresist stripping liquid. Therefore, it can be said that in the method of Patent Document 1, it is difficult to measure the correct photoresist concentration.

[Patent Document 1] JP 07-235487 A

Patent Document 1 is a method using absorbance. The photoresist dissolved in the photoresist stripper is slowly decomposed into low molecules, and the peak of the absorption spectrum is converted to the low wavelength side. As a result, in the photoresist stripping solution, molecules of photoresist components having various absorption spectra are mixed therein.

As a result, in the method using absorbance, the calibration curve obtained in advance cannot be used with time, lacks accuracy, and cannot accurately grasp the problem of the concentration of the photoresist dissolved in the photoresist stripping solution. In addition, the decomposition of the photoresist component of the photoresist peeling liquid causes a change in color and taste, and there is also a problem of error in concentration measurement.

The present invention is an invention that solves such a conventional problem, and aims to provide a photoresist component concentration measurement device and a photoresist concentration measurement method, even if the photoresist dissolved in the photoresist stripper is slowly decomposed into low molecules Therefore, the present invention can also accurately and accurately measure the concentration of the photoresist dissolved in the photoresist stripping solution.

In addition, in order to achieve this objective, the structure of the present invention can select an element contained in the photoresist but not contained in the photoresist stripping stock solution, and measure the concentration of the selected specific element in the photoresist stripping solution, thereby , To achieve the desired purpose.

Specifically, sulfur is selected as the specific element, and more specifically, the amount of sulfur is measured using X-ray fluorescence. Furthermore, more specifically, the concentration of the photoresist component in the photoresist peeling solution is calculated from the measured amount of X-ray fluorescence.

The present invention is constituted by selecting a photoresist stripping solution that is contained in the photoresist but not contained in the photoresist stripping stock solution that will not decompose or change Then, determine the concentration of the selected component in the photoresist stripping solution.

With this configuration, the photoresist dissolved in the photoresist stripping liquid, that is, the concentration of the dissolved photoresist in the photoresist stripping liquid, can be measured accurately and with good accuracy.

As the selected specific component, when the photosensitive material component of the photoresist contains sulfur but the photoresist stripping stock solution does not contain sulfur, it still contains sulfur.

As the selected specific component, it may not be decomposed in the photoresist stripping solution that contains but is not contained in the photoresist stripping stock solution, and can be an element, a chemical substance, or a chemical component.

According to the present invention, the structure of the present invention can select an element contained in the photoresist but not contained in the photoresist stripping stock solution, and measure the concentration of the selected specific element in the photoresist stripping solution.

Thereby, it is possible to provide a photoresist component concentration measuring device and a concentration measuring method, which can accurately and accurately measure the photoresist dissolved in the photoresist stripping liquid as the photoresist concentration in the photoresist stripping liquid The concentration of the agent, that is, the concentration of the dissolved photoresist.

In addition, even if the photoresist component of the photoresist peeling liquid is decomposed and the color and taste are changed, there is no error in the concentration measurement.

10: Device for measuring the concentration of photoresist components

12: Pull out the pipe

12a: pump

12i: suction port

14: Measurement Department

18: Return to piping

18o: discharge outlet

20: X-ray fluorescence measurement device

20a: Inspection Department

24: Through piping

30: Controller

30a: display

30b: Communication line

50: Photoresist stripping device

52: Photoresist stripping liquid tank

54: Conveyor belt

56: Shower device

60: Object to be processed

56a: pump

56b: Shower piping

56c: filter

M: Photoresist stripper

Figure 1 shows the structure of a photoresist peeling device equipped with the photoresist component concentration measuring device of the present invention.

Figure 2 shows the structure of the photoresist component concentration measuring device.

Figure 3 shows the experimental results of measuring the sulfur concentration in the photoresist stripping solution by X-ray fluorescence.

Hereinafter, the photoresist component concentration measuring device of the present invention will be explained using figures. In addition, the following description is an example of one embodiment of the present invention, and the present invention is not limited by the following description. The present invention can be changed freely within the scope not departing from the gist of the present invention.

Fig. 1 shows the structure of the photoresist peeling device 50 equipped with the photoresist component concentration measuring device of this embodiment. The photoresist stripping device 50 has a photoresist stripping liquid tank 52, a conveyor belt 54 for conveying the processed object 60, a shower device 56 for spreading the photoresist stripping liquid M on the processed object 60, and photoresist component concentration Measuring device 10.

The photoresist peeling device 50 operates in the following manner. The to-be-processed object 60 is placed on the conveyor belt 54 and is also transferred. Then, the photoresist stripping liquid M is spread on the photoresist stripping liquid tank 52, and the photoresist is stripped. The photoresist stripping liquid M is recycled.

In the photoresist stripping solution that is contained in the photoresist but not contained in the photoresist stripping stock solution, a component that does not decompose or change is selected. The selected specific component may not be decomposed or changed in the photoresist stripping liquid containing the photoresist but not contained in the photoresist stripping stock solution, and may be an element, a chemical substance, or a chemical component. In addition, the photoresist stripping stock solution here refers to a photoresist stripping solution that has not been used after preparation.

For example, in the photoresist containing photosensitizer In the case of a novolac resin of NQD (naphthoquinone diazidosulfonic ester) and a polymer resin, the photoresist is sulfur or a substance containing sulfur.

For example, when the photoresist stripping stock solution is used as a combination of MEA (monoethanolamine), BDG (diethylene glycol monobutyl ether, diethylene glycol monobutyl ether) and water, the photoresist stripping stock solution does not contain sulfur, that is, it does not contain Sulfur.

If sulfur is selected as the component or element contained in the photoresist but not in the photoresist stripping stock solution, even if the sulfur component changes due to decomposition in the photoresist stripping solution, the sulfur itself will not change .

Therefore, by measuring the concentration of sulfur element selected as a specific element in the photoresist stripping solution, the photoresist dissolved in the photoresist stripping solution can be calculated as the concentration of the photoresist in the photoresist stripping solution The concentration, that is, the concentration of the dissolved photoresist, and the concentration of the photoresist dissolved in the photoresist stripping solution can be accurately and accurately measured.

The circulated photoresist stripping liquid M is stored in the photoresist stripping liquid tank 52, and is sent to the shower device 56 by the pump 56a through the shower device piping 56b. In addition, the shower pipe 56b preferably includes a filter 56c. In this way, it can be prevented from clogging due to the solid content of the photoresist.

Then, after peeling off the photoresist of the to-be-processed object 60, it returns to the photoresist peeling liquid tank 52. In this way, the photoresist stripping liquid M can be recycled. The photoresist in the photoresist stripping liquid M is dissolved in the photoresist stripping liquid M after being stripped.

Thereby, the photoresist dissolved in the photoresist stripping liquid tank 52 is The concentration will increase over time. Therefore, as for the photoresist stripping liquid M in the photoresist stripping liquid tank 52, when the dissolved photoresist reaches a predetermined concentration, part or all of it will be exchanged with a new liquid as the photoresist stripping stock solution.

The photoresist component concentration measuring device 10 of the present invention takes out the photoresist stripping liquid M from the photoresist stripping liquid tank 52, measures the amount of sulfur as a specific element in the dissolved photoresist, and then returns to the photoresist again Stripping liquid tank 52.

In addition, the symbol 12i is the suction port of the photoresist stripping liquid M, and the symbol 18o is the discharge port of the photoresist stripping liquid M returning to the photoresist stripping liquid tank 52 after the amount of sulfur in the dissolved photoresist is measured.

In addition, although not shown, the photoresist stripping liquid M after the amount of sulfur is measured may not be returned to the photoresist stripping liquid tank 52 but may be discharged out of the system.

In FIG. 2, the structure of the photoresist component concentration measuring device 10 is shown. The photoresist component concentration measuring device 10 has a drawing pipe 12 connected to the inside of the photoresist stripping liquid tank 52, and a measuring unit for measuring the photoresist stripping liquid M passing through the drawing pipe 12 and the inside of the drawing pipe 14. Return the photoresist stripping liquid M to the return pipe 18 of the photoresist stripping liquid tank 52.

Furthermore, there is an X-ray fluorescence measuring device 20 as a measuring means for measuring the amount of sulfur as the selected specific element in the photoresist stripping liquid M in the measuring section 14, and also has The controller 30 as a calculation means calculates the concentration of the photoresist component in the photoresist stripping liquid M from the measured value of the sulfur content of the X-ray fluorescence measuring device 20.

The pipe 12 is pulled out to take out a part of the photoresist stripping liquid M from the photoresist stripping liquid tank 52. In addition, the pull-out pipe 12 is provided with a pump 12a for transferring the photoresist stripping liquid M. Pump 12a is set on the downstream side The portion 14 adjusts the pressure in the drawing pipe 12 to a pressure at which the photoresist stripping liquid M can be processed without obstacles.

The measuring unit 14 as a measuring means is continuously installed on the drawing pipe 12 to allow the X-ray fluorescence measuring device 20 to measure the amount of sulfur in the photoresist stripping liquid M, that is, to measure the amount of sulfur. In Fig. 2, a portion continuously provided in the drawing pipe 12 is shown. In order to irradiate the photoresist peeling liquid M with X-rays from the X-ray fluorescence measurement device 20, the measurement unit 14 uses a material that can transmit X-rays.

The type of the measuring unit 14 as a measuring means is not particularly limited. For example, there is a type of measuring container in which a resin line through which X-rays can be transmitted through X-ray fluorescence is viewed from X-ray fluorescence is used as the measuring part 14 and is connected to the pull-out pipe 12, and the photoresist stripping liquid M is stored in the pull-out pipe 12 once. It is continuously installed on the drawing pipe 12.

In this embodiment, a case will be described in which a pipe (hereinafter referred to as "transmissive pipe") 24 that communicates with the pull-out pipe 12 and passes through X-rays constitutes the measurement unit 14.

In this structure, the amount of sulfur in the photoresist stripping liquid M flowing through the pipe 24 is measured. The transmission pipe 24 is difficult to degrade in the photoresist stripping liquid, and is made of a material that can transmit X-ray fluorescence. As an example, the material can be fluororesin, polyester, polypropylene, etc., as long as it is a material that can transmit X-ray fluorescence when measuring sulfur by X-ray fluorescence.

In addition, it is not necessary to form all the transmission pipes 24 with a material that can transmit X-rays. That is, only the part that is irradiated with X-rays and generates X-ray fluorescence is used as the transmission pipe 24, and the other parts can be made of metal such as stainless steel. tube. In addition, only a part of the drawn pipe 12 may be used as a pipe material that transmits X-rays.

In addition, it is possible to receive the photoresist stripping liquid M from the pull-out pipe 12 once in the measurement container, and then measure the amount of sulfur by measuring the photoresist stripping liquid in the container.

A return pipe 18 communicates with the transmission pipe 24. Then, the photoresist stripping liquid M sucked up from the photoresist stripping liquid tank 52 by the pump 12a flows through the transmission pipe 24 through the pull-out pipe 12, and returns to the photoresist stripping liquid tank through the return pipe 18 52.

The X-ray fluorescence measuring device 20 as a measuring means measures sulfur (S) as the selected specific element in the resist stripping liquid M. The positive photoresist is composed of NQD (Naphthoquinone Diazide Sulfonate) as a photosensitizer and novolac resin.

The photosensitive NQD becomes indene carboxylic acid in the presence of alcohol and is dissolved in an alkaline solution. As a result, the bond between the novolak resin is severed, and the photosensitive resist is peeled off and dissolved in the alkaline solution.

The photoresist stripping liquid M is composed of a new liquid that is the original liquid of the photoresist stripping liquid M, dissolved novolac resin, and dissolved NQD including the structure changed after the dissolution. The dissolved novolac resin and the dissolved NQD that contains the structural change after dissolution are called photoresist components. The photoresist component is a dissolved photoresist that has been dissolved.

These photoresist components, that is, the dissolved photoresist, are not in a single form, but also include large solidified components, and components that dissolve and decompose into the basic structure of novolac resin.

In addition, the more the photoresist stripper M is circulated, the more new New photoresist composition. In addition, the longer the elapsed time, the photoresist component that is the dissolved photoresist will begin to decompose and change.

However, the amount of sulfur present in NQD does not change. Therefore, by measuring the amount of sulfur in the photoresist stripping liquid M, the concentration of the photoresist component in the photoresist stripping liquid M, that is, the concentration of the dissolved photoresist that has been dissolved, can be stably measured.

In addition, here, the so-called amount of sulfur, that is, the amount of sulfur, can measure the intensity of sulfur X-rays. In other words, the so-called sulfur content refers to the characteristic X-ray intensity (kcps) of sulfur.

As described above, the photoresist component concentration measuring device of the present invention uses sulfur in the photoresist component as an indicator of the concentration of the photoresist component, that is, the dissolved photoresist concentration. Therefore, if the component in the photoresist stripping solution contains a sulfuric acid group, the concentration of the photoresist component cannot be accurately measured.

Although it has been explained, most of the photoresist stripping liquid is discarded or discharged part of the used photoresist stripping liquid, and the rest is used after replenishing a new liquid or regenerated liquid as the photoresist stripping stock solution.

When the photoresist stripping stock solution contains sulfur, the current amount of sulfur does not come from the photoresist component or the photoresist stripping solution itself.

Therefore, the photoresist component concentration measuring device 10 of the present invention can be used in a case where it is composed only of a material that does not contain sulfur in the photoresist stripping liquid.

An element contained in the photoresist but not contained in the photoresist stripping stock solution is selected, and the concentration of the selected specific element in the photoresist stripping solution is measured.

In this way, the element itself will not decompose or decompose in the photoresist stripper. There is no change, so even if the dissolved photoresist dissolved in the photoresist stripping solution is decomposed, the concentration of the dissolved photoresist dissolved in the photoresist stripping solution can be accurately determined.

The detection unit 20a of the X-ray fluorescence measurement device 20 shows a structure in which the X-ray irradiation unit and the light receiving unit are integrated in FIG. 2. However, the irradiating part and the light receiving part may be configured separately.

The amount of sulfur in the photoresist stripping liquid M measured by the X-ray fluorescence measurement device 20 may include a controller 30 in order to convert it into a concentration. The controller 30 calculates the photoresist component concentration in the photoresist stripping liquid M from the flow rate of the photoresist stripping liquid M passing through the piping 24 and the measured amount of sulfur measured by the X-ray fluorescence measuring device 20, and It is displayed on the display 30a.

In addition, the photoresist component concentration can be calculated as follows. First, the correction liquid determined by the concentration of the photoresist component flows through the permeation pipe 24 at a predetermined flow rate. Then, the X-ray fluorescence measurement device 20 is used to measure it.

By this measurement, the calibration curve of the photoresist component concentration relative to the measured sulfur amount is obtained. Based on this calibration curve, the concentration of the photoresist component in the photoresist stripping liquid M can be calculated.

The controller 30 may also have a transmission line 30b, which transmits a signal to other devices when the concentration of the photoresist component reaches a certain value. This is because when the photoresist component concentration of the photoresist stripping liquid M reaches a certain value, all or part of the photoresist stripping liquid M in the photoresist stripping liquid tank 52 needs to be replaced.

Here, the operation of the photoresist component concentration measuring device 10 having the above structure will be described. The photoresist peeling liquid M is transferred to the photoresist component concentration measuring device 10 through the pull-out pipe 12 (see FIG. 1).

The internal pressure in the drawing pipe 12 is adjusted by the pump 12 a, and the photoresist stripping liquid M is sent to the transmission pipe 24. The photoresist stripping liquid M that has passed through the pipe 24 passes through the return pipe 18 and returns to the photoresist stripping liquid tank 52.

The X-ray fluorescence measurement device 20 measures the amount of sulfur in the photoresist stripping liquid M flowing through the transmission pipe 24 under the instruction of the controller 30. Then, the measured value is notified to the controller 30.

The controller 30 calculates the sulfur concentration in the photoresist stripping liquid M using a calibration curve prepared in advance. Therefore, the controller 30 that performs such actions can be called a calculation means. The calculated sulfur concentration is displayed on the display 30a. Also, it is sent as a signal to other machines (30b).

As described above, the photoresist component concentration measuring device 10 of the present invention measures the content of the photoresist stripping liquid M based on the dissolving of the sulfur atoms in the photoresist that is not contained in the stock solution of the photoresist stripping liquid. The photoresist component concentration, so even if the dissolved photoresist component in the photoresist stripping liquid M decomposes and changes over time, or the color taste changes, accurate concentration measurement can still be performed.

[Example]

The following shows the results of an experiment using an X-ray fluorescence measuring device to measure the components of the photoresist. As the analysis device, a scanning X-ray fluorescence analysis device (ZSX Primus II) manufactured by Rigaku Corporation was used.

The photoresist stripping liquid uses a composition of 19% MEA (monoethanolamine), 60% BDG (diethylene glycol monobutyl ether), and 21% water. No material contains sulfur.

As the photoresist component of the sample, novolac resin is used After the positive photoresist is exposed to light, the substance that becomes dry or powder is used. Sulfur is used as a specific element.

<Experimental method>

Regarding the photoresist stripping solution, the photoresist component (powder) as the sample was dissolved to produce a simulated photoresist stripping solution of 0.1, 0.3, 0.6, 1.0 wt%. Then, the X-ray (Ka-ray) intensity of only sulfur in each simulated photoresist stripping liquid was measured using the aforementioned analysis device. The result is shown in Figure 3.

In Figure 3, the horizontal axis is the concentration of the photoresist component that is the concentration of the dissolved photoresist (expressed as PR addition concentration [wt%]), and the vertical axis is the intensity of X-ray fluorescence (expressed as " X-ray intensity (kcps)”).

Referring to Fig. 3, the concentration of photoresist added to the stripping solution and the X-ray intensity from sulfur (S) are highly positively correlated in a wide range from a low concentration of less than 0.1wt% to a high concentration of 1.0wt% . Also, if the same sample is left for a week and then measured, no change will be seen.

This chart is the result of using X-ray fluorescence to determine the pre-concentration of the photoresist components, that is, the concentration of the dissolved photoresist is the amount of sulfur in the known photoresist stripping solution. This can be used as a calibration curve for calculation.

When using X-ray fluorescence to determine the concentration of photoresist components, that is, the concentration of dissolved photoresist that has been dissolved is the amount of sulfur in the photoresist stripping solution, the photoresist can be obtained from the X-ray intensity. The concentration of the ingredients.

This can also calculate the concentration. In addition, the calibration curve may not be the graph shown in Fig. 3, but may be a table composed of numerical data.

【Industrial Profitability】

The photoresist component concentration measuring device of the present invention can be applied to The photoresist stripping process during microfabrication using photolithography technology.

10‧‧‧Resist composition concentration measuring device

12i‧‧‧Suction port

18o‧‧‧Exhaust outlet

50‧‧‧Photoresist stripping device

52‧‧‧Photoresist stripper tank

54‧‧‧Conveyor belt

56‧‧‧Water shower

56a‧‧‧Pump

56b‧‧‧Shower Piping

56c‧‧‧Filter

60‧‧‧Processed objects

M‧‧‧Resist stripper

Claims (9)

A photoresist component concentration measuring device, which is characterized in that it is used in a photoresist containing NQD (naphthoquinone diazide sulfonate) and novolac resin, and a photoresist stripping device equipped with a photoresist stripping liquid tank The photoresist stripping liquid tank uses a photoresist stripping liquid that does not contain sulfur, and an X-ray fluorescence measuring device is used to measure the amount of sulfur in the photoresist stripping liquid. For example, the photoresist component concentration measuring device of the first item of the scope of patent application includes a calculation means that can calculate the photoresist component concentration in the photoresist stripping liquid from the measurement amount of the X-ray fluorescent device. For example, the photoresist component concentration measuring device of the second item of the scope of patent application, wherein the measurement is performed using a drawing pipe connected to the photoresist stripping liquid tank and a measuring means provided in the drawing pipe. For example, the photoresist component concentration measurement device of the third item of the scope of patent application includes an X-ray transmission pipe connected to the above-mentioned pull-out pipe. For example, the photoresist component concentration measuring device of item 3 of the scope of patent application includes a measuring container for receiving the photoresist stripping liquid discharged from the pull-out pipe. A method for measuring the concentration of photoresist components, which is characterized by: using a photoresist containing NQD (naphthoquinone diazide sulfonate) and novolac resin, and using a photoresist stripping solution that does not contain sulfur. The photoresist stripping device of the photoresist stripping solution tank, wherein the amount of sulfur in the photoresist stripping solution is measured by an X-ray fluorescence measuring device. For example, the method for measuring the concentration of photoresist components in the sixth item of the scope of patent application includes a calculation step, which can calculate the concentration of the photoresist component in the photoresist stripping liquid from the amount of sulfur. For example, the method for measuring the concentration of photoresist components in the seventh item of the patent application, wherein the photoresist stripping liquid is taken out from the photoresist stripping liquid tank, and the taken out and flowing state of the photoresist stripping liquid is measured The amount of sulfur in. For example, the method for measuring the concentration of photoresist components in the scope of the patent application, wherein the photoresist stripping liquid is taken out from the photoresist stripping liquid tank, and the taken-out photoresist stripping liquid is temporarily stored in the measuring container , And then determine the amount of sulfur.

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