TW201628080A - Silicon concentration or etch selectivity measurement method and measurement device - Google Patents

Abstract

Provided are a silicon concentration measurement method and measurement device capable of continuous inline measurement of a silicon concentration within an etching solution. Further, a sensor head for silicon concentration measurement is provided that is used in the measurement method and is not easily influenced by the fixation state of a crystal oscillator or the temperature difference between the sensor head and etching solution. Provided are an etch selectivity measurement method and measurement device capable of accurate, practical, continuous inline measurement of the etching speed ratio between a silicon nitride film and silicon oxide film. The silicon concentration measurement device is provided with a crystal oscillator 11 that is covered in a silicon oxide film and is made to come into contact with the etching solution 25 of a substrate processing device 26, a vibration frequency detection means 21 for vibrating the crystal oscillator 11 while detecting the vibration frequency of the same, and a calculation means 24 for calculating the silicon concentration within the etching solution 25 on the basis of the rate of change of the vibration frequency.

Description

Measuring method and measuring device for germanium concentration or etching selectivity ratio

The present invention relates to a measuring method and a measuring device for measuring a helium concentration of a germanium concentration when etching a semiconductor wafer or the like, and a measuring head for measuring the germanium concentration used in the measuring method and the measuring device, particularly One is applied as a technique for continuously measuring the germanium concentration in-line for a substrate processing apparatus.

Further, the present invention relates to a method for measuring the etching rate of a tantalum nitride film (Si ₃ N ₄ or the like) and a tantalum oxide film (SiO ₂ ) when etching a semiconductor wafer or the like by using such a measurement method of germanium concentration. Measurement methods and measurement devices are selected that are more selective than etching, and are particularly useful as a technique for continuously measuring the selection ratio in-line for a wafer processing apparatus.

In the case of etching a tantalum nitride film with a phosphoric acid solution in a semiconductor wafer process, in general, in addition to the presence of a tantalum nitride film on the surface of the wafer, an oxide film having a hafnium oxide film as a device structure is also present. Wait. In this case, the etching target is only a tantalum nitride film, and it is generally required that the hafnium oxide film is hardly etched by the treatment liquid. That is, abnormal etching of the ruthenium oxide film may cause problems such as a decrease in device performance or a failure of the device to function. All in all, control The ratio of the ratio of the tantalum nitride film to the yttrium oxide film to the etching rate is important.

In order to etch a tantalum nitride film and a hafnium oxide film by a high-temperature phosphoric acid solution, it is known that a tantalum nitride film is etched by water in a phosphoric acid solution, and a hafnium oxide film is etched by phosphoric acid in a phosphoric acid solution. In addition, the concentration of antimony in the phosphoric acid solution changes during etching, which affects the etching rate of the hafnium oxide film.

On the other hand, there is known an etching rate evaluation method for measuring a etching rate by coating a material to be measured to a crystal oscillator, and contacting the measuring material coated to the crystal oscillator to an etching liquid, and The etching rate of the material to be measured is measured in real time and quantitatively from the oscillation frequency of the crystal oscillator (see, for example, Patent Document 1). Further, in this document, the use of a ruthenium oxide film as a material to be measured has been disclosed.

[Previous Technical Literature] [Patent Literature]

Patent Document 1: Japanese Laid-Open Patent Publication No. Hei 10-92789.

However, in the case of etching the tantalum nitride film with a phosphoric acid solution, as described above, since the hafnium oxide film is also etched and the germanium concentration in the etching liquid is gradually increased l, so it is necessary to control the selection ratio of etching and control the concentration of germanium. Therefore, as in the evaluation method described in Patent Document 1, even if the ruthenium concentration of the ruthenium oxide film can be known, the ruthenium concentration cannot be measured. Therefore, it is difficult to accurately control the etching selectivity ratio depending on the ruthenium concentration. Further, since it is difficult to use a spectroscopic analysis method or the like, there has been no method for instantaneously measuring the concentration of germanium in the etching liquid in an on-line manner.

On the other hand, in a conventional QCM (quartz-crystal microbalance) sensor in which a material to be measured is coated to a crystal oscillator, since the corrosion resistance to the etching liquid is not sufficiently considered, Therefore, the use in the etching solution has a problem that durability is lowered. Therefore, there is a need for a sensor head configuration that only exposes the crystal oscillator to the etchant.

However, there is a problem that the measurement accuracy is changed due to the fixing manner when the crystal oscillator is held at the sensor head, and the measured value is affected by the temperature difference between the sensor head and the etching liquid, causing the temperature of the crystal oscillator to be unstable. And the problem caused by the breakage of the crystal oscillator.

However, in the case where the technique disclosed in Patent Document 1 is respectively applied to the etching of the tantalum nitride film and the hafnium oxide film and the tantalum nitride film and the hafnium oxide film are etched together for the purpose of measuring the selectivity ratio of the phosphoric acid treatment, Since the etching rate of the tantalum nitride film is faster than that of the tantalum oxide film, it is necessary to frequently perform replacement of a crystal oscillator coated with a tantalum nitride film, etc., and thus it is difficult to be a practical method. In addition, in this method, it has to be divided into two tests in practice. The measurement unit has problems such as complicating the measurement system, increasing the size, and increasing the cost.

On the other hand, a method of calculating the ratio of the etching rate of the tantalum nitride film to the etching rate of the tantalum oxide film is also considered, but the etching rate of the tantalum nitride film is the temperature of the etching liquid. The function of the concentration, and the temperature and concentration time are changing during the semiconductor wafer process, so the accuracy of the calculated selection ratio is insufficient. Further, similarly, the etching rate of the ruthenium oxide film is a function of the temperature and concentration of phosphoric acid and the concentration of ruthenium in the phosphoric acid solution.

Accordingly, it is an object of the present invention to provide a measuring method and a measuring apparatus capable of continuously measuring the erbium concentration of cerium in an etching solution in an on-line manner. Further, it is an object of the present invention to provide a measurement method for measuring the erbium concentration of erbium concentration in an etchant in an in-line manner and which is not easily fixed by a crystal oscillator and/or a sensor head and an etchant. The sensor head is used to measure the radon concentration that affects the temperature difference.

Further, another object of the present invention is to provide a measurement of an etching selectivity ratio in which the etching rate of a tantalum nitride film/yttria film treated by phosphoric acid is measured in a linear and continuous manner with high precision and practicality. Method and measuring device.

The above object can be achieved by the present invention described below.

That is, the method for measuring the concentration of germanium according to the present invention includes the steps of: contacting an oxide liquid coated with a crystal oscillator to an etching liquid of a substrate processing apparatus, and detecting an oscillation frequency while oscillating the crystal oscillator; and The step of calculating the enthalpy concentration in the etching liquid in the rate of change of the oscillation frequency.

According to the method for measuring the concentration of germanium according to the present invention, by the step of detecting the oscillation frequency, the etching state of the tantalum oxide film can be continuously and quantitatively quantified, and the correlation between the rate of change according to the oscillation frequency and the concentration of germanium can be obtained. The relationship between the enthalpy concentration in the etching solution is calculated in a timely manner. In this case, although the correlation between the enthalpy concentration and the rate of change of the oscillation frequency is affected by the temperature of the etchant, the temperature is controlled to be fixed or temperature measurement is performed, and the correlation in the temperature is utilized. The radon concentration can be accurately calculated. As a result, it is possible to provide a measurement method capable of continuously measuring the erbium concentration of the cerium concentration in the etching liquid in an in-line manner.

In the case where the temperature of the etching liquid is not controlled to be fixed, it is preferable to further include a step of measuring the temperature of the etching liquid; and in the step of calculating the concentration of germanium in the etching liquid, according to the temperature of the etching liquid and the foregoing The enthalpy concentration in the etching liquid was calculated from the rate of change of the oscillation frequency.

That is, as shown in FIG. 8, it can be seen that although the rate of change of the oscillation frequency is different when the radon concentration is different, there is a high correlation between the two. And, the oscillation frequency The rate of change of the rate is proportional to the etching rate (etching rate) of the hafnium oxide film due to the QCM principle described later. Further, as shown in FIG. 3, in the case where the temperature of the etching liquid and the phosphoric acid concentration are fixed, although the etching rate of the yttrium oxide film exhibits a high correlation with the yttrium concentration, the correlation also changes when the temperature is different. The present invention utilizes a high correlation between the rate of change of the oscillation frequency and the concentration of germanium in the etching solution, and controls the temperature of the etching liquid to be fixed to thereby eliminate the influence of temperature, or to consider the influence of temperature, thereby being able to be continuous in line. The concentration of germanium in the etching solution was measured sexually.

In the above case, preferably, the method further comprises the step of measuring the concentration of phosphoric acid in the etching solution; and in the step of calculating the concentration of germanium in the etching solution, according to the temperature of the etching solution and the concentration of the phosphoric acid and the oscillation frequency The rate of change of the enthalpy in the etching solution was calculated. The correlation between the enthalpy concentration and the rate of change of the oscillation frequency (in other words, the etch rate of the ruthenium oxide film) is also affected by the concentration of phosphoric acid in the etchant. In particular, in the case where the phosphoric acid concentration in the etching solution changes, the phosphoric acid concentration is measured and the correlation between the phosphoric acid concentrations is utilized, whereby the germanium concentration can be calculated with higher accuracy. Further, in the case where the temperature of the etching liquid in the etching treatment tank differs from the temperature of the etching liquid in the oscillation number detecting means portion, a correction means may be additionally provided.

Further, it is preferable to calculate the etching rate of the yttrium oxide film in accordance with the rate of change of the oscillation frequency. The etching rate of the yttrium oxide film can be easily calculated according to the QCM principle described later in accordance with the rate of change of the oscillation frequency, and the rate of change of the oscillation frequency can be continuously measured in an online manner, thereby being able to be utilized for yttrium oxide. Control of the selection ratio between the etching rate of the film and the etching rate of the tantalum nitride film.

Further, it is preferable to use a sensor head that liquid-tightly holds the crystal oscillator with a sealing member for pressing the periphery of the crystal oscillator, and heats the crystal oscillator by a heating means. Thus, by holding the structure of the crystal oscillator liquid-tightly with a sealing member, the influence of the fixed state of the crystal oscillator is reduced, and the crystal oscillator is heated by heating means, thereby causing the sensor head to The temperature difference of the etching liquid becomes small, and it is hard to influence the temperature change of the crystal oscillator, and the germanium concentration can be measured with higher precision.

On the other hand, the apparatus for measuring the concentration of radon according to the present invention includes a crystal oscillator that coats a ruthenium oxide film that is in contact with an etching solution of the substrate processing apparatus, and an oscillation number detecting means that oscillates the crystal oscillator. The oscillation frequency is detected, and the calculation means calculates the concentration of germanium in the etching liquid based on the etching rate of the hafnium oxide film calculated from the change in the oscillation frequency of the crystal oscillator and the rate of change of the oscillation frequency.

According to the apparatus for measuring the concentration of germanium according to the present invention, the etching state of the tantalum oxide film can be continuously and quantitatively quantified in-line by the crystal oscillator and the oscillation number detecting means, and can be used according to the oscillation frequency of the crystal oscillator. The calculation method of calculating the enthalpy concentration in the etching liquid by calculating the correlation between the change rate and the enthalpy concentration instantaneously calculates the erbium concentration. In this case, although the enthalpy concentration and oscillation frequency The correlation between the rate of change of the etchant is affected by the temperature of the etchant. However, the temperature is controlled to be fixed or measured by a temperature measuring means, and the correlation in the temperature is utilized, whereby the enthalpy can be accurately calculated. concentration. As a result, it is possible to provide a measuring device capable of continuously measuring the erbium concentration of the cerium concentration in the etching liquid in an in-line manner.

In the case where the temperature of the etching liquid is not controlled to be fixed, it is preferable to further include a temperature measuring means for measuring the temperature of the etching liquid; the calculation means is calculated based on the temperature of the etching liquid and the rate of change of the oscillation frequency. The concentration of germanium in the aforementioned etching solution.

In the above case, it is preferable to further include a concentration measuring means for measuring a concentration of phosphoric acid in the etching liquid; and the calculating means calculates the etching based on a temperature of the etching liquid, a concentration of the phosphoric acid, and a rate of change of the oscillation frequency. The concentration of cesium in the liquid. Although the correlation between the erbium concentration and the etch rate of the ruthenium oxide film is affected by the phosphoric acid concentration in the etchant, the concentration of the phosphoric acid is measured to measure the phosphoric acid concentration, and the phosphoric acid concentration is utilized in the calculation means. The correlation is used to calculate the radon concentration more accurately.

Further, it is preferable that the calculation means includes calculation for calculating an etching rate of the yttrium oxide film in accordance with a rate of change of the oscillation frequency. The etch rate of the ruthenium oxide film can be easily calculated from the change rate of the oscillation frequency according to the QCM principle described later, and the change of the oscillation frequency is continuously measured online. The speed can be utilized to control the selection ratio of the etching rate of the ruthenium oxide film and the tantalum nitride film.

Furthermore, it is preferable to further include a sensor head that liquid-tightly holds the crystal oscillator with a sealing member for pressing the periphery of the crystal oscillator, and heats the crystal oscillation by heating means. Device. Thus, by holding the structure of the crystal oscillator liquid-tightly with a sealing member, the influence of the fixed state of the crystal oscillator is reduced, and the crystal oscillator is heated by heating means, thereby causing the sensor head to The temperature difference of the etching liquid becomes small, and it is hard to influence the temperature change of the crystal oscillator, and the germanium concentration can be measured with higher precision.

On the other hand, the sensor head for measuring the erbium concentration according to the present invention includes: a crystal oscillator that coats the ruthenium oxide film; and a sealing member that presses the periphery of the crystal oscillator to hold the crystal oscillator in a liquid-tight manner; And heating means for heating the crystal oscillator.

According to the sensor head for measuring the erbium concentration according to the present invention, by the structure in which the crystal oscillator is liquid-tightly held by the sealing member, the influence (measurement error) caused by the fixed state of the crystal oscillator becomes small, and by means of heating By heating the crystal oscillator described above, the temperature difference between the sensor head and the etching liquid is made small, and it is difficult to influence the temperature change of the crystal oscillator, and the germanium concentration can be measured with higher precision.

In the above case, it is preferable to have the inner side of the crystal oscillator There is an internal space in which only the communication path communicates to the outside; and a valve member is provided in the communication path, and the communication path is closed when the liquid flows into the internal space. According to this configuration, when the internal space is expanded by the heating of the sensor head, air or the like can be discharged through the communication path, and in the case where the crystal oscillator is broken and the etching liquid flows into the internal space of the sensor head, By closing the flow path by the valve member, it is possible to avoid the problem at the time of breakage.

On the other hand, the measurement method of the etching selectivity of the present invention includes continuously changing the oscillation frequency of the crystal oscillator while bringing the yttrium oxide film coated on the crystal oscillator into contact with the etching liquid of the substrate processing apparatus. a step of calculating an etching rate of the hafnium oxide film; a step of calculating an etching rate of the tantalum nitride film of the etching liquid; and continuously calculating nitrogen according to the calculated etching rate of the hafnium oxide film and an etching rate of the tantalum nitride film The step of the ratio of the etching speed of the ruthenium film/yttria film.

According to the method for measuring the etching selectivity of the present invention, the step of continuously calculating the etching rate of the hafnium oxide film and the step of calculating the etching rate of the tantalum nitride film can quantitatively quantify the hafnium film in line continuity and with high precision. The etching rate with the tantalum nitride film. Therefore, by continuously calculating the ratio of the etching speeds, the selection ratio can be measured in line continuity and with high precision.

In this case, in the step of calculating the etching rate of the tantalum nitride film, it is preferable to continuously calculate the tantalum nitride film from the measured concentration and/or temperature while measuring the concentration and/or temperature of the etching liquid. Etching speed. In from In the case where the etching rate of the tantalum nitride film is continuously calculated based on the correlation between the concentration of the etching liquid and the temperature, and the temperature and the etching rate, the crystal oscillator can be accurately calculated without changing the crystal oscillator. The etching rate of the film. As a result, it is possible to provide a method of measuring the etching selectivity ratio in which the ratio of the etching rate of the tantalum nitride film/yttria film can be measured in a line-continuous manner with high precision and practicality.

In the above case, it is preferable to include an arithmetic process for converting the etching rate of the hafnium oxide film coated on the crystal oscillator into the etching of the hafnium oxide film formed on the substrate when calculating the ratio of the etching rates. speed. In the case where the yttrium oxide film coated on the crystal oscillator is different from the method of forming the yttrium oxide film formed on the substrate, since the etching speed is also different, the etching selection can be measured with higher precision by performing such arithmetic processing. ratio.

Further, it is preferable that a ruthenium oxide film is formed in the above-described crystal oscillator sputtering. By forming by sputtering, a homogeneous hafnium oxide film can be formed at low cost, and since the etching rate is fast, the measurement sensitivity of the etching selectivity can be improved. Further, as long as a homogeneous ruthenium oxide film can be formed at low cost, other film formation methods may be used, for example, PVD (physical vapor deposition) or CVD (chemical vapor phase deposition). Chemical vapor deposition method (thermal CVD, plasma CVD, photo CVD, etc.), coating/sintering of an organic tantalum material, and the like.

Moreover, it is preferable to calculate the erbium concentration in the etching liquid from the calculated etching rate of the cerium oxide film. This is because in the case where the tantalum nitride film is etched with a phosphoric acid solution, since the hafnium oxide film is also etched and the germanium concentration in the etching liquid gradually rises, the selection ratio of the etching is controlled and the concentration of the germanium is controlled to be effective. the way.

On the other hand, the apparatus for measuring the etching selectivity of the present invention includes a crystal oscillator that coats a ruthenium oxide film that is in contact with an etching liquid of the substrate processing apparatus, and an oscillation number detecting means that oscillates the crystal oscillator. The oscillation frequency is detected, and the calculation means is to continuously calculate the tantalum nitride film/yttria film based on the etching rate of the hafnium oxide film calculated from the oscillation frequency change of the crystal oscillator and the etching rate of the tantalum nitride film. The ratio of the etch rate.

According to the etching selection ratio measuring apparatus of the present invention, the etching state of the yttrium oxide film can be continuously and quantitatively quantified in-line by the crystal oscillator and the oscillation number detecting means, and the etching speed of the tantalum nitride film can be fixed by control The concentration and temperature or concentration measurement means are quantified by the concentration and temperature measured by the temperature measuring means. Therefore, by continuously calculating the ratio of the etching speed by the arithmetic means, the selection ratio can be measured in line continuity and with high precision.

In this case, it is preferable to further provide at least one of a concentration measuring means for measuring the concentration of the etching liquid and a temperature measuring means for measuring the temperature of the etching liquid; The tantalum nitride film is continuously calculated from the etching rate of the yttrium oxide film calculated by the change in the oscillation frequency of the crystal oscillator and the etching rate of the tantalum nitride film calculated from the measured concentration and/or temperature of the etching liquid. The ratio of the etching rate of the hafnium oxide film. In the case where the etching rate of the tantalum nitride film is continuously calculated from the relationship between the concentration of the etching liquid and the temperature depending on the relationship between the concentration of the etching liquid and the temperature and the etching rate, the crystal oscillator can be replaced without being replaced, and the size can be reduced. The compact and inexpensive system calculates the etching rate of the tantalum nitride film with high precision. As a result, it is possible to provide a measuring apparatus capable of measuring the etching selectivity of the tantalum nitride film/yttria film in a line-continuous manner with high precision and practicality. Further, in the case where the temperature of the etching liquid in the etching treatment tank differs from the temperature of the etching liquid in the oscillation number detecting means portion, a correction means may be additionally provided.

In the above case, it is preferable that the calculation means includes an arithmetic processing for converting an etching rate of the hafnium oxide film coated on the crystal oscillator into an oxidation formed on the substrate when calculating a ratio of etching rates. The etching speed of the ruthenium film. In the case where the yttrium oxide film coated on the crystal oscillator is different from the method of forming the yttrium oxide film formed on the substrate, since the etching speed is also different, the etching selection can be measured with higher precision by performing such arithmetic processing. ratio.

Further, for the reason described above, it is preferable that a ruthenium oxide film is formed by sputtering on the crystal oscillator. For the reasons described above, it is preferable that the arithmetic means further perform an arithmetic process, and the arithmetic processing is calculated from The etching rate of the cerium oxide film was calculated to calculate the cerium concentration in the etching liquid.

Furthermore, it is preferable to further include a sensor head that liquid-tightly holds the crystal oscillator with a sealing member for pressing the periphery of the crystal oscillator, and transmits the signal from the heating means The aforementioned crystal oscillator is heated by heat. In this manner, by holding the structure of the crystal oscillator in a liquid-tight manner with a sealing member, the influence of the fixed state of the crystal oscillator is reduced, and the crystal oscillator is heated by heat transfer from the heating means, thereby sensible The temperature difference between the measuring head and the etching liquid becomes small, and it is not easy to be affected by the temperature change of the crystal oscillator, and the germanium concentration can be measured with higher precision.

In the above case, it is preferable that an inner space is provided inside the crystal oscillator, and only a communication path communicates with the outside; and a valve member is provided in the communication path, and is connected when the liquid flows into the inner space. The path is blocked. According to this configuration, when the internal space is expanded by the heating of the sensor head, air or the like can be discharged through the communication path, and in the case where the crystal oscillator is broken and the etching liquid flows into the internal space of the sensor head, By closing the flow path by the valve member, it is possible to avoid the problem at the time of breakage.

10‧‧‧Measurement container

11‧‧‧ crystal oscillator

12‧‧‧Sensor head (sensor head for 矽 concentration measurement)

13‧‧‧ Sealing members

13a‧‧‧Outer sealing member

13b‧‧‧Inside sealing member

14‧‧‧heating means

15‧‧‧Box components

16‧‧‧Sensor

16a‧‧‧through hole

16b‧‧‧Internal space

16c‧‧‧Connected path

16d‧‧‧Valve components

17‧‧ ‧ sales

18‧‧‧ Nut components

18a, 19d‧‧‧ male screw

19a‧‧‧First cover

19b‧‧‧second cover

19c, 19e, 32a‧‧‧ female screw

19f‧‧‧through

21‧‧‧Analysis of the number of oscillations

22‧‧‧ Temperature measurement means

22a‧‧‧Temperature Sensor

23‧‧‧Concentration measurement

23a‧‧‧Measurement unit

24‧‧‧ arithmetic means

24a‧‧‧Related information

25‧‧‧etching solution

25a‧‧‧Measurement unit

26‧‧‧Substrate processing unit

27‧‧‧Recycling piping

27a‧‧‧ pump

28‧‧‧ Cover

29‧‧‧Importing Department

31‧‧‧Socket holder

31a‧‧‧ insertion port

31b‧‧‧ socket pin

32‧‧‧Sensor head body

33, 34‧‧‧Importing section of thermocouple

35‧‧‧Exporting Department

36‧‧‧Exhaust Department

38‧‧‧Circulation slot

43‧‧‧Connecting Department

45‧‧‧ container body

46‧‧‧ rubber heater

Fig. 1A is a schematic configuration diagram showing an example of a measuring device for a radon concentration of the present invention.

Fig. 1B is a schematic configuration diagram showing an example of a measuring apparatus for etching selectivity according to the present invention.

Fig. 2A is a cross-sectional view showing an example of a main part of a measuring device for a radon concentration of the present invention.

Fig. 2B is a cross-sectional view showing an example of a sensor head for measuring a radon concentration of the present invention.

Fig. 2C is a cross-sectional view showing an exploded state of an example of a sensor head for measuring a cesium concentration according to the present invention.

Fig. 3 is a graph showing the results of immersing a ruthenium-doped ruthenium wafer in a phosphoric acid solution, etching it, changing the ruthenium concentration and the phosphoric acid temperature, and measuring the etching rate.

Fig. 4 is a flow chart showing an example of data processing in the arithmetic means.

Fig. 5 is a cross-sectional view showing another example of the main part of the apparatus for measuring the concentration of radon according to the present invention.

Fig. 6 is a plan view showing another example of the main part of the apparatus for measuring the concentration of radon according to the present invention.

Fig. 7 is a schematic block diagram showing another example of the apparatus for measuring the concentration of radon according to the present invention.

Fig. 8 is a view showing the result of changing the yttrium concentration in the phosphoric acid etching solution (temperature: 150 ° C, phosphoric acid concentration: 87% by weight), etching the yttrium oxide film coated on the crystal oscillator, oscillating the crystal oscillator, and measuring the amount of change in the oscillation frequency. Chart.

Figure 9 is a diagram showing the difference between the frequency of the crystal oscillator (QCM), the phosphoric acid temperature, and the temperature of the crystal oscillator in the case where the sensor head is preheated and the sensor head is not heated. chart.

Figure 10 shows the phosphorus in different temperatures (150 ° C, 160 ° C, 170 ° C) A graph of the relationship between the acid concentration and the etching rate of the tantalum nitride film.

(矽 concentration measuring device)

As shown in FIG. 1A, the apparatus for measuring the concentration of radon according to the present invention includes a crystal oscillator 11 which is coated with a ruthenium oxide film which is brought into contact with an etching solution 25 of a substrate processing apparatus 26 such as a wafer processing apparatus; and an oscillation number detection. The means 21 detects the oscillation frequency while causing the crystal oscillator 11 to oscillate. In the present embodiment, an example is shown in which the circulation container 27 is provided with the measurement container 10 and the crystal oscillator 11 is brought into contact with the etching liquid 25 inside the measurement container 10.

The type of the etching liquid 25 is not limited as long as it is an etching liquid which changes the etching liquid speed of the cerium oxide film according to the cerium concentration. For example, a mixed solution of a diluent such as phosphoric acid and water, or a diluent such as sulfuric acid or water can be exemplified. Mixture, hydrofluoric acid, buffered hydrofluoric acid, and the like. In the present embodiment, an example in which a high-temperature mixed liquid of phosphoric acid and water is used and a substrate (for example, a germanium wafer for a semiconductor (not shown) is immersed and a tantalum nitride film is etched is shown.

Although the crystal oscillator 11 is coated with a hafnium oxide film, a hafnium oxide film can be formed on one or both of the electrodes provided on the surface of the flat crystal plate. In the present embodiment, the crystal oscillator 11 is held by the sensor head 12 and an iridium oxide film is formed on one of the electrodes.

The formation of yttrium oxide film can be sputtered, reactively sputtered, and vacuum evaporated. When plating or the like is formed by sputtering or the like, the etching rate can be increased, and the detection sensitivity of the etching rate can be improved. Further, as long as a homogeneous ruthenium oxide film can be formed at low cost, other film formation methods may be used, for example, CVD (thermal CVD, plasma CVD, photo CVD, etc.), application/sintering of an organic ruthenium material, and the like.

The formation of the hafnium oxide film can be performed up to a thickness of 500 nm, and in the case where the etching rate of the hafnium oxide film is about 0.25 nm/min, when it is used once for 10 minutes, measurement of about 200 times can be used. The crystal oscillator 11 coated with the hafnium oxide film is exchanged in accordance with the degree of consumption of the hafnium oxide film.

In the present invention, the etching rate of the ruthenium oxide film can be measured by the principle of QCM (Crystal Oscillator Micro Scale Method). The QCM is a mass sensor for measuring the amount of adhesion using a property in which the resonance frequency changes depending on the mass of the substance attached to the surface of the crystal oscillator 11. As shown in FIG. 2A, the crystal oscillator 11 is preferably held by the sensor head 12 inside the measuring container 10. The measurement container 10 including the sensor head 12 will be described later.

The oscillation number detecting means 21 is electrically connected to the crystal oscillator 11, and detects the oscillation frequency while the crystal oscillator 11 is oscillated. Various types of QCM sensors are commercially available, and measurement devices useful for mass measurement using an oscillating circuit and/or a QCM sensor that oscillates the QCM sensor are also commercially available. For the above-mentioned devices, the QCM principle is used, and an example of measurement applied to the etching rate is disclosed, for example, in Japanese Laid-Open Patent Publication No. Hei 10-92789, No. 2002-500828.

As shown by the Sauerbrey formula described below, the crystal oscillator 11 using the QCM principle can calculate the mass change amount of the attached substance from the change in the oscillation frequency of the crystal oscillator 11. Therefore, by measuring the amount of change in the oscillation frequency at predetermined time intervals, the amount of change in mass per unit time can be obtained, that is, the etching rate can be obtained. In addition, according to this formula, it can be understood that the rate of change of the oscillation frequency is proportional to the etching speed.

In the Sorbray formula:

ΔF is the frequency change.

Δm is the amount of mass change.

F _o is the fundamental frequency.

ρ _Q is the crystal density.

μ _Q is the crystal shear stress.

A is the gold electrode area.

As shown in FIG. 1A, it is preferable that the apparatus for measuring the concentration of germanium of the present invention has means for controlling the temperature of the etching liquid 25 to be fixed or used. The temperature measuring means 22 is used to measure the temperature. The temperature measuring means 22 includes a temperature sensor 22a, and the temperature sensor 22a uses a thermocouple, a temperature measuring resistor, or the like.

In addition, the method and the like described in the item of the prior art of the Unexamined-Japanese-Patent No. 11-154665 can be exemplified by the method of controlling the temperature and the concentration of the etchant to be fixed. For example, in the case where the etching solution is an aqueous phosphoric acid solution, a heating device having a heater power of a boiling point or higher of a phosphoric acid aqueous solution is used to control the input of pure water while maintaining the temperature of the phosphoric acid aqueous solution at the boiling point temperature while continuing the heating. The amount of the phosphoric acid aqueous solution and the phosphoric acid concentration are kept constant.

Further, the apparatus for measuring the concentration of germanium according to the present invention includes a calculation means 24 for calculating the concentration of germanium in the etching liquid 25 in accordance with the temperature of the etching liquid 25 and the rate of change of the oscillation frequency. At this time, although the correlation between the rate of change of the oscillation frequency and the concentration of germanium (see FIG. 8) can be utilized, the etching rate and the germanium concentration of the hafnium oxide film calculated from the change in the oscillation frequency of the crystal oscillator 11 can be used. The correlation between the etching rates of the hafnium oxide film is used to calculate the concentration of germanium in the etching solution 25. The correlation utilized at this time uses a correlation that at least considers the temperature of the etching solution 25.

Fig. 3 is a graph showing the results of immersing a ruthenium-doped ruthenium wafer in phosphoric acid (an aqueous solution having a phosphoric acid concentration of 87.4% by weight), etching the ruthenium concentration and the phosphoric acid temperature, and measuring the etching rate. As shown by the results, the yttrium concentration has a high correlation with the etch rate of the yttrium oxide film, and is related. The relationship will differ depending on the temperature of the etching solution 25.

Although the graph of FIG. 3 is a measurement result of a phosphoric acid concentration of 87.4% by weight, in the case of changing the phosphoric acid concentration, the radon concentration in the temperature of the etching solution 25 and the etching rate of the hafnium oxide film in various phosphoric acid concentrations are The relationship between the two is different.

Therefore, in the present invention, particularly in the case where the phosphoric acid concentration in the etching solution 25 is changed, it is preferable to take into consideration the correlation of the phosphoric acid concentration in addition to the temperature of the etching solution 25. Therefore, in the present invention, it is preferable to further include a concentration measuring means 23 for measuring the concentration of phosphoric acid in the etching solution. In the present embodiment, the display concentration measuring means 23 is provided with the measuring unit 23a and the measuring unit 23a is provided in the circulation pipe 27. The concentration measuring means 23 will be described in detail later.

Therefore, in the present embodiment, the display calculation means 24 calculates the correlation between the temperature of the etching liquid 25 and the concentration of germanium in the phosphoric acid concentration and the rate of change of the oscillation frequency (or the etching rate of the hafnium oxide film). An example of the situation of radon concentration.

The arithmetic unit 24 can perform the above-described calculation using a microprocessor, a computer, or the like, and using the related material 24a stored in the memory device. With respect to the related material 24a, a function that mathematically relates the correlation shown in Fig. 3 can be utilized. This function is based on the temperature of the etching solution 25 and the concentration of phosphoric acid. Degree to set. Further, the correlation between the enthalpy concentration and the rate of change of the oscillation frequency can be obtained in advance from the graph shown in FIG. 8, and a function that mathematically relates the correlation can be used.

The calculation unit 24 performs the calculation according to the flow shown in FIG. 4 in accordance with the computer program. The flow in this example is that the arithmetic means 24 reads the sampled data at a certain time interval and performs an operation.

In step S1, the time interval of the steps S2 to S5 described below is performed in accordance with the time interval of the preset sampling. In terms of the sampling interval, for example, it is set to 60 seconds to 600 seconds.

In step S2, sampling of the number of oscillations by the oscillation number detecting means 21 is performed. Although the number of oscillations or the value corresponding to the number of oscillations is output from the oscillation number detecting means 21, the mass of the attached substance can be calculated and the calculated result can be output. By outputting such a value at regular intervals, the rate of change of the oscillation frequency per unit time and/or the etching rate can be obtained by the arithmetic means 24.

In step S3, sampling of the temperature by the temperature measuring means 22 is performed. The temperature or the value corresponding to the temperature is output from the temperature measuring means 22. By outputting such a value at regular time intervals, the related data 24a corresponding to the temperature in the time can be read into the arithmetic means 24.

In step S4, sampling of the phosphoric acid concentration by the concentration measuring means 23 is performed. The concentration of the phosphoric acid or the value corresponding to the concentration of the phosphoric acid is output from the concentration measuring means 23. By outputting such a value at regular intervals, the correlation data 24a corresponding to the phosphoric acid concentration in the time can be read into the calculation means 24.

In step S5, the correlation data 24a read by the calculation means 24 is used as the temperature of the etching solution 25 and the concentration of the yttrium concentration in the phosphoric acid concentration and the oscillation frequency and/or the etching rate of the yttrium oxide film. The relationship is used to take advantage of. In the calculation means 24, the concentration of germanium in the etching solution 25 is calculated from the rate of change of the oscillation frequency and/or the etching rate in accordance with the correlation.

In step S6, the result of the operation by the arithmetic means 24 in step S5 is output. In the form of the output, it can be displayed, printed, etc. for the display device, or can be output as an operation signal for controlling the radon concentration, the etching rate, and the like. In this case, the germanium concentration, the etching rate, and/or the value corresponding to the output are output.

(etching selection ratio measuring device)

The measuring apparatus of the etching selectivity of the present invention measures the etching selectivity by the above-described measuring method of the germanium concentration of the present invention. As shown in FIG. 1B, the apparatus for measuring the etching selectivity of the present invention includes a crystal oscillator 11 that coats a ruthenium oxide film that contacts the etching liquid 25 of the substrate processing apparatus 26, and an oscillation number detecting means 21. Check the crystal oscillator 11 while oscillating Measure the oscillation frequency. In the present embodiment, an example is shown in which the circulation container 27 is provided with the measurement container 10 and the crystal oscillator 11 is brought into contact with the etching liquid 25 inside the measurement container 10.

The type of the etching liquid 25 is not particularly limited as long as it is an etching solution for etching the tantalum nitride film and the hafnium oxide film, and examples thereof include a mixed solution of a diluent such as phosphoric acid and water, and a diluent such as sulfuric acid or water. Mixture, etc.

As shown in FIG. 1B, it is preferable that the apparatus for measuring the etching selectivity of the present invention has a concentration measuring means 23 for measuring the concentration of phosphoric acid in the etching solution. In the present embodiment, the display density measuring means 23 is an example in which the measuring unit 23a is provided and the measuring unit 23a is provided in the circulation pipe 27. The concentration measuring means 23 will be described in detail later.

Further, it is preferable that the measuring device for the etching selectivity of the present invention is provided with a temperature measuring means 22 for measuring the temperature of the etching liquid 25. The temperature measuring means 22 includes a temperature sensor 22a, and the temperature sensor 22a uses a thermocouple, a temperature measuring resistor, or the like.

Further, the measuring apparatus for the etching selectivity of the present invention includes the arithmetic means 24, and the calculating means 24 is based on the etching speed of the hafnium oxide film calculated from the change in the oscillation frequency of the crystal oscillator 11, and is measured or controlled to be fixed. The ratio of the etching liquid 25 and the etching rate of the tantalum nitride film calculated by the temperature were used to calculate the ratio of the etching rate of the tantalum nitride film/yttria film. at this time, It is preferable to continuously calculate the etching rate of the tantalum nitride film from the correlation between the concentration and temperature of the etching liquid 25 in accordance with the correlation between the concentration of the etching liquid 25 and the etching speed of the tantalum nitride film. In this case, the method described in the item of the prior art of Japanese Laid-Open Patent Publication No. Hei 11-154665 can be exemplified as a method for controlling the temperature and the concentration of the etchant to be fixed. For example, in the case where the etching solution is an aqueous phosphoric acid solution, a heating device having a heater power of a boiling point or higher of a phosphoric acid aqueous solution is used to control the input of pure water while maintaining the temperature of the phosphoric acid aqueous solution at the boiling point temperature while continuing the heating. The amount of the phosphoric acid aqueous solution and the phosphoric acid concentration are kept constant.

In the present invention, it is preferable to further perform an arithmetic processing for calculating the germanium concentration in the etching liquid 25 from the calculated etching rate of the hafnium oxide film by the arithmetic means 24. However, the calculation of the enthalpy concentration can also be calculated from the correlation between the rate of change of the oscillation frequency and the enthalpy concentration.

That is, as shown in FIG. 8, it can be seen that although the rate of change of the oscillation frequency is different when the radon concentration is different, there is a high correlation between the two. Further, the rate of change of the oscillation frequency is proportional to the etching rate (etching rate) of the hafnium oxide film due to the QCM principle. Further, as shown in FIG. 3, in the case where the temperature of the etching liquid and the phosphoric acid concentration are fixed, although the etching rate of the yttrium oxide film exhibits a high correlation with the phosphoric acid concentration, the correlation also changes when the temperature is different. The present invention utilizes a high correlation between the rate of change of such an oscillation frequency and the concentration of germanium in the etching solution, in which case the temperature of the etching solution is considered. The effect is such that the concentration of germanium in the etching solution can be continuously measured in line.

On the other hand, the erbium concentration in the etching solution 25 can be calculated from the correlation between the etching rate of the yttrium oxide film calculated from the oscillation frequency change of the crystal oscillator 11 and the yttrium concentration and the etching rate of the yttrium oxide film. The correlation utilized at this time uses a correlation that at least considers the temperature of the etching solution 25.

The arithmetic unit 24 can perform the above-described calculation using a microprocessor, a computer, or the like, and using the related material 24a stored in the memory device. The related data 24a includes relevant information for calculating the etching rate of the tantalum nitride film and related information for calculating the germanium concentration in the etching solution 25.

As a data for calculating the enthalpy concentration, a function that mathematically relates the correlation shown in FIG. 3 and the like can be utilized. This function is set in accordance with the temperature of the etching solution 25 and the phosphoric acid concentration. Further, the correlation between the enthalpy concentration and the rate of change of the oscillation frequency can be obtained in advance from the graph shown in FIG. 8, and a function that mathematically relates the correlation can be used.

For the correlation data for calculating the etching rate of the tantalum nitride film, a function that mathematically relates the correlation shown in FIG. 10 can be utilized. Fig. 10 is a graph showing the relationship between the phosphoric acid concentration in different temperatures (150 ° C, 160 ° C, 170 ° C) and the etching rate of the tantalum nitride film, and it can be understood that the concentration and temperature of the etching solution 25 can be based on the etching liquid 25 Concentration and temperature with tantalum nitride film The correlation between the etching rates is used to calculate the etching rate of the tantalum nitride film.

The calculation unit 24 performs the calculation according to the flow shown in FIG. 4 in accordance with the computer program. The flow in this example is that the arithmetic means 24 reads the sampled data at a certain time interval and performs an operation. The processing in each of steps S1 to S6 is the same as that described above.

In particular, in step S5, the correlation data 24a read by the calculation means 24 is used as a correlation relationship for calculating the etching rate of the tantalum nitride film from the concentration and temperature of the etching liquid 25 at that time. Thereby, the ratio of the etching rate of the tantalum nitride film/yttria film was continuously calculated based on the calculated etching rate of the tantalum nitride film and the etching rate of the hafnium oxide film calculated as described above.

Further, the related data 24a is used as a correlation between the enthalpy concentration in the temperature and the phosphoric acid concentration of the etching solution 25 and the change rate of the oscillation frequency and/or the etching rate of the yttrium oxide film in the etching time. In the calculation means 24, the concentration of germanium in the etching solution 25 can be calculated from the rate of change of the oscillation frequency and/or the etching rate in accordance with the correlation.

In the present invention, it is preferable to include an arithmetic processing for converting the etching rate of the hafnium oxide film coated on the crystal oscillator 11 into a hafnium oxide film formed on the substrate when calculating the ratio of the etching rates. Etching speed. The arithmetic processing can be based on the etching rate of the yttrium oxide film obtained in advance. The correlation is made with the etching rate of the hafnium oxide film formed on the substrate. Usually, due to the proportional relationship between the two, a specific proportionality constant can be used in this correlation.

In step S6, the result of the operation by the arithmetic means 24 in step S5 is output. The output mode may be displayed, printed, or the like for the display device, or may be output as an operation signal for controlling the etching selectivity, the germanium concentration, the etching rate, and the like. In this case, the etch selectivity ratio, the erbium concentration, the etch rate, and/or the values corresponding to the etch are output.

(Measurement method of 矽 concentration)

The method for measuring the ruthenium concentration of the present invention is preferably carried out using the above-described ruthenium concentration measuring device of the present invention. That is, the method for measuring the erbium concentration according to the present invention includes a step of contacting the yttrium oxide film coated on the crystal oscillator 11 to the etching liquid 25 of the substrate processing apparatus, and detecting the oscillation frequency while causing the crystal oscillator 11 to oscillate; And a step of calculating the concentration of germanium in the etching solution 25 based on the rate of change of the oscillation frequency. In the above embodiment, the step of measuring the temperature of the etching liquid 25 is further included, and an example in which the concentration of germanium in the etching liquid 25 is calculated in accordance with the temperature of the etching liquid 25 and the rate of change of the oscillation frequency is shown.

As described above, the step of calculating the etching rate of the hafnium oxide film can be carried out using the substrate processing apparatus 26, the crystal oscillator 11, the oscillation number detecting means 21, and the arithmetic means 24 shown in FIG. In addition, to measure the etch The step of temperature of the engraving can be carried out using temperature measuring means 22. Further, the step of calculating the enthalpy concentration can be performed by, for example, the flow shown in FIG. 4 using the arithmetic means 24.

In the present invention, as in the above embodiment, it is preferable to further include a step of measuring the concentration of phosphoric acid in the etching solution 25; in the step of calculating the concentration of germanium in the etching solution 25, depending on the temperature of the etching solution 25 The concentration of ruthenium in the etching solution 25 was calculated from the rate of change in the phosphoric acid concentration and the oscillation frequency. The step for measuring the phosphoric acid concentration can be carried out using the concentration measuring means 23 for measuring the phosphoric acid concentration. Further, it is preferable to include a step of calculating the etching rate of the hafnium oxide film in accordance with the rate of change of the oscillation frequency. Further, the method for measuring the ruthenium concentration of the present invention is preferably carried out using the sensor head 12 of the present invention to be described later.

(Measurement method of etching selection ratio)

The method of measuring the etching selectivity of the present invention can be carried out using the above-described etching selectivity measuring device of the present invention. That is, the measurement method of the etching selectivity of the present invention includes the continuity of the oscillation frequency from the crystal oscillator 11 while the cerium oxide film coated on the crystal oscillator 11 is brought into contact with the etching liquid 25 of the substrate processing apparatus. a step of calculating an etching rate of the hafnium oxide film; a step of continuously calculating an etching rate of the tantalum nitride film of the etching solution 25; and continuously, in accordance with the calculated etching rate of the hafnium oxide film and the etching rate of the tantalum nitride film The procedure of calculating the ratio of the etching rate of the tantalum nitride film/yttria film is calculated. In this case, it is preferred to measure etching on one side. The etching rate of the tantalum nitride film was continuously calculated from the measured concentration and temperature with respect to the concentration and temperature of the liquid 25.

As described above, the step of calculating the etching rate of the hafnium oxide film can be carried out using the substrate processing apparatus 26, the crystal oscillator 11, the oscillation number detecting means 21, and the arithmetic means 24 shown in FIG. Further, as described above, the step of calculating the etching rate of the tantalum nitride film can be carried out using the temperature measuring means 22, the concentration measuring means 23, and the arithmetic means 24 shown in FIG. Further, the step of calculating the ratio of the etching rate and the step of calculating the concentration of germanium can be carried out, for example, using the arithmetic means 24 to carry out the flow shown in FIG.

In the present invention, as in the above embodiment, it is preferable to further include a step of measuring the concentration of phosphoric acid in the etching solution 25; in the step of calculating the concentration of germanium in the etching solution 25, depending on the temperature of the etching solution 25 The concentration of ruthenium in the etching solution 25 was calculated from the rate of change in the phosphoric acid concentration and the oscillation frequency. The step for measuring the phosphoric acid concentration can be carried out using the concentration measuring means 23 for measuring the phosphoric acid concentration. Further, the measurement method of the etching selectivity of the present invention is preferably carried out using the sensor head 12 described later.

(sensor head for 矽 concentration measurement)

As shown in FIGS. 2A to 2C, the sensor head 12 used in the method for measuring the etching selectivity of the present invention is provided with a crystal oscillator 11 which is coated with a hafnium oxide film, and a sealing member 13 which presses the crystal oscillation. Around the device 11 The crystal oscillator 11 is held in a liquid-tight manner; and the heating means 14 heats the crystal oscillator 11 by heat transfer.

As shown in FIG. 9, in the case where the sensor head 12 is not preheated, the temperature of the crystal oscillator 11 may be unstable due to the temperature difference between the sensor head 12 and the etching liquid 25, and the frequency is not affected by this. stable. On the other hand, in the case where the sensor head 12 is preheated, it is understood that the temperature difference between the sensor head 12 and the etching liquid 25 becomes small, and the temperature of the crystal oscillator 11 is quickly stabilized, and the frequency is also affected by this. Fast and stable.

Thus, the crystal oscillator 11 is heated by the heat transfer from the heating means 14, whereby the temperature difference between the sensor head 12 and the etching liquid 25 becomes small, and it is hard to be affected by the temperature change of the crystal oscillator 11 (measurement error). The radon concentration can be measured with higher precision.

As shown in Fig. 2C, in the example shown in Fig. 2C, the sealing member 13 is constituted by the outer side sealing member 13a and the inner side sealing member 13b. The inner seal member 13b has an L-shaped cross section, and when the outer seal member 13a is fitted into the inner seal member 13b, the periphery of the crystal oscillator 11 is pressed by the outer seal member 13a and the inner seal member 13b. The sealing member 13 is formed of a fluororesin such as PTFE (polytetrafluoroethylene) or a corrosion-resistant material such as fluororubber. Further, in the present invention, a fluororesin such as PTFE or a perfluoric material such as PTFE having a high etching liquid temperature and high heat resistance is preferably used.

Further, the inner seal member 13b is fitted to the frame member 15, whereby the seal member 13 is held by the frame member 15. With this configuration, the crystal oscillator 11 can be easily replaced from the sensor head 12 without breaking the crystal oscillator 11. The frame member 15 is formed of a fluororesin such as PTFE, a glass epoxy resin, FRP (fiber reinforced plastics), CFRP (carbon fiber reinforced plastics), or glassy carbon.

The frame member 15 is embedded and held in the sensor stage 16. The frame member 15 and the sensor stage 16 are detachable, whereby the frame member 15 can be prevented from being damaged and replaced safely when the crystal oscillator 11 is replaced. The sensor stage 16 is formed of a material such as fluororesin such as PTFE, glass epoxy resin, FRP, CFRP, or glassy carbon.

The inner seal member 13b, the frame member 15, and the sensor stage 16 are provided with a through hole 16a or the like for allowing a pin 17 to pass therethrough. The pin 17 can be electrically connected to the electrode terminal of the crystal oscillator 11 by penetrating the pin 17.

The heating means 14 is constituted by a surface heater or the like, and is fixed to the sensor head 12 by joining the male screw portion 19d of the second cover 19b to the female screw portion 19c of the first cover 19a. The second cover 19b has a through hole 19f for electrically connecting the pin or the like to the heating means 14. The surface heater or the like in this case is preferably a rubber heater or a polyimide film (Kapton). A heater or the like is representative of a heat-resistant/resistant rubber, a heat-resistant/resistant film, or the like.

The sensor stage 16 is fixed to the sensor head 12 by concatenating the male screw portion 18a of the nut member 18 to the female screw portion 19e of the second cover 19b. In this case, the sealing member 13 for holding the crystal oscillator 11 in a liquid-tight manner is adhered to the inner surface of the first casing 19a and fixed to the sensor head 12. The nut member 18 is made of a fluororesin such as PTFE or a material such as PEEK (polyetheretherketone).

A socket holder 31 is inserted inside the nut member 18, and the socket holder 31 has an insertion opening 31a of the pin 17. The insertion port 31a has an O-ring, is inserted into the pin 17 in a liquid-tight state, and is electrically connected to a socket pin 31b. An O-ring is also held on the outer circumferential surface and the outer wall surface of the socket holder 31, so that liquid does not intrude into the sensor head 12.

The sensor head body 32 is provided with a female screw portion 32a, and the male screw portion 19d of the second cover 19b is screwed, thereby being integrally fixed to the sensor head body 32. An O-ring is also held on the outer wall surface of the sensor head body 32, and the O-ring is adhered to the inner wall surface of the first cover 19a to be a liquid-tight structure. The first cover 19a, the second cover 19b, and the receptacle holder 31 are formed of a material having heat resistance, chemical resistance, and thermal conductivity such as glassy carbon.

As shown in FIG. 2B (not shown in FIG. 2C), it is preferable that the inner side of the crystal oscillator 11 in the sensor head 12 is provided with an inner space 16b, only the communication path 16c is communicated to the outside; and the valve member 16d The system is disposed in the communication path 16c, and closes the communication path 16c when the liquid flows into the internal space 16b.

In the present embodiment, an example in which the valve member 16d which is a spherical floating body is provided in the space in which the diameter is expanded in the communication path 16c is shown. Since the floating body is usually located at the lower portion of the space through which the diameter is expanded, when the internal space 16b is expanded by the heating of the sensor head 12, the air can be discharged or the like via the communication path 16c. Further, in the case where the crystal oscillator 11 is broken to cause the etching liquid 25 to flow into the internal space 16b of the sensor head 12, the floating body is closed to the communication path 16c, whereby corrosion due to the chemical liquid at the time of breakage can be avoided. And the problem caused by the circuit.

In the case of a floating body, a material having a specific gravity lower than that of the etching liquid 25 or a hollow spherical object can be used. Further, the boundary between the communication path 16c and the space through which the diameter is expanded functions as a valve seat. In the present invention, a valve member 16d for operating by the inflow pressure of the liquid and closing the communication path 16c may be provided instead of the floating body.

As shown in FIG. 2A, the sensor head 32 is a container whose side is open, and a first cover 19a or the like is provided on the side surface, thereby forming a sealed structure. The sensor head body 32 is fixed by a joint portion 43 for passing the wiring 24 through. To the measuring container 10, the sensor head 12 is provided inside the measuring container 10. The sensor head body 32 is formed of a material such as fluororesin such as PEEK or PTFE.

As shown in FIG. 1, the circulation pipe 27 in which the etching liquid 25 is provided in the measuring container 10. The circulation pipe 27 is provided with a pump 27a which is useful for circulation. Thereby, the etching speed can be measured more instantaneously.

The measurement container 10 is provided with an introduction portion 29 and a discharge portion 35 of the etching liquid 25, and is provided with an exhaust portion 36 for initial exhaust. Further, introduction portions 33, 34 for thermocouples for measuring temperature and temperature in the container 10 are provided.

Further, a rubber heater 46 for heating the inside is provided on the outer circumference of the container body 45, and a heat insulating member 27 is provided on the outer circumference of the rubber heater 46. The upper surface of the container body 45 is open and sealed by the lid body 28. The sensor body 28 is attached to the sensor head 12 via the joint portion 43. The lid body 28 is joined to the container body 45 by bolts or the like.

Further, it is preferable that the crystal oscillator 11 is a crystal oscillator having a high oscillation frequency of approximately 30 MHz, and thus the measurement system has various external noise intrusions. The main noises include noise caused by external electromagnetic waves, high temperature of the etching liquid 25 belonging to the electrolyte, temperature changes, and noise caused by the flow of noise. Therefore, the aforementioned members need to be made into electrical conductors and With grounding. For example, the first cover 19a and the second cover 19b may be glass-like carbon which is directly a conductor, but a member such as the sensor head body 32 may be used as a conductive fluororesin or CFRP (in which a conductor such as carbon fiber is mixed). A carbon resin-reinforced plastic or the like is used, and all of the external components of the sensor head 12 for measuring the radon concentration are formed as a conductor and grounded. In addition, the wiring between the sensor head 12 for detecting the radon concentration and the oscillation number detecting means 21 is a coaxial cable that is resistant to external noise, and further covers the wiring with a wiring covering portion in which a conductor is formed and The conductor can be grounded. In this way, various external noises can be prevented from intruding into the measurement system, and the frequency can be measured with higher precision.

(Measurement method of concentration of phosphoric acid concentration)

The concentration measuring means 23 for phosphoric acid concentration is preferably a spectroscopic measuring means for measuring the light absorbing characteristics of the etching liquid 25, thereby measuring the concentration of the etching liquid 25. Thereby, the concentration of phosphoric acid in the etching solution 25 can be measured in an on-line manner, and the correlation between the phosphoric acid concentrations can be utilized, whereby the concentration of germanium can be calculated with higher accuracy. Further, the phosphoric acid concentration is also used for calculation of the etching rate of the tantalum nitride film.

The light absorption characteristic of the etching liquid 25 is measured by the intensity value of the transmitted light. Specifically, the phosphoric acid solution to be measured can be introduced into the light transmitting portion of the measuring unit 25a, and light of different wavelengths can be transmitted through the light transmitting portion to measure the transmission. The intensity value of the light is calculated from the intensity value, and the acid concentration in the phosphoric acid solution is determined using the absorbance and the calibration curve.

The calibration line type system can be obtained by introducing a sample of a phosphoric acid solution having a known concentration into a unit for transmitting light or the like, and transmitting light of a different wavelength in the infrared wavelength band to the measuring unit 25a or the like to measure the intensity of the transmitted light. The value is repeated for a plurality of samples, and the absorbance is calculated from the intensity values of the plurality of samples, thereby being used as a calibration line between the absorbance and the acid concentration in the phosphoric acid solution.

The method of measuring the concentration of the phosphoric acid having such a spectroscopy is described in detail in JP-A-2013-51334 and JP-A-2012-028580, and the present invention can be carried out by the methods described in the above.

[Other Embodiments]

The present invention is not limited to the above embodiment, and can be changed to the following embodiments.

(1) In the above embodiment, the circulation pipe 27 of the substrate processing apparatus 26 is provided with the measurement container 10 and the crystal oscillator 11 is brought into contact with the etching liquid 25 inside the measurement container 10. However, in the present invention, The measurement container 10 can be provided in a continuous waste liquid pipe of the etching liquid 25 of the substrate processing apparatus 26.

Further, as shown in FIGS. 5 and 6, a flow cell 38 may be provided in the pipe 37, and the crystal oscillator 11 may be brought into contact with the flow groove 38. Part of the etching solution 25. In this case, although the sensor head 12 similar to that of the above-described embodiment is provided, it is preferable that the sensor head 12 is provided with a flow groove 38 which is considered to be circular in plan view. Further, as shown in the figure, in the case where the sensor head 12 is disposed such that the crystal oscillator 11 is horizontal, it is preferable to move the floating body for blocking the communication path when the liquid flows into the internal space. A space that expands in diameter is formed in a manner that is in the up and down direction.

(2) In the above embodiment, an example in which a sensor head for etching selection ratio measurement is used is shown. However, as shown in Fig. 7, the present invention can be directly implemented using a commercially available QCM sensor. In this case, the etching liquid 25 may be immersed in a state in which the QCM sensor coated with the ruthenium oxide film is directly used, and the temperature sensor 22a of the temperature measuring means 22 or the like may be immersed in the etching liquid 25 in the same manner.

(3) In the above embodiment, it has been shown that the concentration measuring means 23 for measuring the concentration of phosphoric acid in the etching solution 25 is further included, and the calculating means 24 is based on the temperature of the etching solution 25 and the rate of change of the phosphoric acid concentration and the oscillation frequency. Although an example of the concentration of cerium in the etching solution 25 is calculated, in the present invention, the measurement of the phosphoric acid concentration may be omitted when calculating the cerium concentration. In this case, for example, the correlation of the temperatures of the etching liquids using the average can be utilized during the measurement.

(4) In the above embodiment, although an example in which a tantalum nitride film is etched by a phosphoric acid solution in a semiconductor wafer process is shown, even if fluorine is used The present invention can also be carried out in the case of etching an yttrium oxide film such as acid or buffered hydrofluoric acid. That is, the etching rate in the etching liquids also has a certain correlation with the germanium concentration, and the correlation depends on the temperature of the etching liquid. In this case, the concentration measuring means for measuring the phosphoric acid concentration is omitted.

(5) In the above embodiment, it has been shown that the tantalum nitride film is continuously calculated from the measured concentration and temperature while measuring the concentration and temperature of the etching liquid in the step of calculating the etching rate of the tantalum nitride film. As an example of the etching rate, the etching rate of the tantalum nitride film may be continuously calculated from the concentration and/or temperature of the etching liquid while controlling the concentration and/or temperature of the etching liquid. The method for controlling the concentration and/or the temperature of the etching liquid to be fixed may be exemplified by a method of using an indicator such as a temperature indicating regulator (TIC; Temperature Indicating Controller); Means for detecting the concentration and/or temperature of the etching solution, means for operating the concentration and/or temperature, and means for operating the operating means in such a manner that the detection signal from the detecting means is close to the set value by the detected value method. In terms of control of the control means, it may be PID (Proportional-Integral-Derivative) control or ON (ON) / OFF (OFF) control.

10‧‧‧Measurement container

11‧‧‧ crystal oscillator

12‧‧‧Sensor head (sensor head for 矽 concentration measurement)

21‧‧‧Analysis of the number of oscillations

22‧‧‧ Temperature measurement means

22a‧‧‧Temperature Sensor

23‧‧‧Concentration measurement

23a‧‧‧Measurement unit

24‧‧‧ arithmetic means

24a‧‧‧Related information

25‧‧‧etching solution

26‧‧‧Substrate processing unit

27‧‧‧Recycling piping

27a‧‧‧ pump

28‧‧‧ Cover

Claims (22)

A method for measuring a ruthenium concentration, comprising: a step of contacting an etchant film coated with a crystal oscillator to an etching solution of a substrate processing apparatus and detecting an oscillation frequency while oscillating the crystal oscillator; and The rate of change is a step of calculating the concentration of ruthenium in the etchant. The method for measuring the concentration of ruthenium according to claim 1, further comprising the step of measuring the temperature of the etchant; and calculating the concentration of ruthenium in the etchant, according to the temperature of the etchant and the oscillating frequency The rate of change was calculated for the concentration of ruthenium in the etching solution. The method for measuring the concentration of rhodium according to claim 1, further comprising the step of measuring the concentration of phosphoric acid in the etching solution; and in the step of calculating the concentration of germanium in the etching solution, depending on the temperature of the etching solution and the phosphoric acid The concentration of the ruthenium in the etchant is calculated as the rate of change of the concentration and the oscillation frequency. The method for measuring the concentration of germanium described in claim 1 includes the step of calculating the etching rate of the tantalum oxide film in accordance with the rate of change of the oscillation frequency. A method for measuring a radon concentration as recited in claim 1, wherein a sensor head is used, and the sensor head is liquid-tightly held by a sealing member for pressing a periphery of the crystal oscillator, and The crystal oscillator is heated by a heating means. The apparatus for measuring the concentration of germanium includes a crystal oscillator that coats a tantalum oxide film that contacts an etching liquid of a substrate processing apparatus, and an oscillation number detecting means that detects an oscillation frequency while oscillating the crystal oscillator; The calculation means calculates the concentration of germanium in the etching liquid based on the rate of change of the oscillation frequency. The apparatus for measuring the concentration of germanium according to claim 6, further comprising temperature measuring means for measuring the temperature of the etching liquid; wherein the calculating means calculates the etching liquid based on a temperature of the etching liquid and a rate of change of the oscillation frequency The concentration of cesium in the medium. The apparatus for measuring the concentration of germanium according to claim 6, further comprising concentration measuring means for measuring a concentration of phosphoric acid in the etching solution; wherein the calculating means is based on a temperature of the etching solution and a concentration of the phosphoric acid and the oscillation frequency The rate of change was calculated for the concentration of ruthenium in the etching solution. The apparatus for measuring a radon concentration according to claim 6, wherein the calculation means includes calculation for calculating an etching rate of the hafnium oxide film in accordance with a rate of change of the oscillation frequency. The apparatus for measuring the concentration of radon according to claim 6, further comprising a sensor head that liquid-tightly holds the crystal oscillator with a sealing member for pressing a periphery of the crystal oscillator, And heating the aforementioned crystal oscillator by heating means. A sensor head for measuring a radon concentration, comprising: a crystal oscillator, which is coated with a hafnium oxide film; and a sealing member that presses the periphery of the crystal oscillator to hold the crystal oscillator in a liquid-tight manner; and a heating means The aforementioned crystal oscillator is heated. The sensor head for measuring a radon concentration according to claim 11, wherein an inner space is provided inside the crystal oscillator, and only a communication path is communicated to the outside; and a valve member is provided in the communication path, and When the liquid flows into the aforementioned internal space, the aforementioned through path is blocked. A method for measuring an etching selectivity ratio includes continuously calculating the yttrium oxide film from a change in an oscillation frequency of the crystal oscillator while bringing an etchant film coated on a crystal oscillator into contact with an etching solution of a substrate processing apparatus a step of etching rate; a step of calculating an etching rate of the tantalum nitride film of the etching solution; and continuously calculating a tantalum nitride based on the calculated etching rate of the hafnium oxide film and an etching rate of the tantalum nitride film The step of the ratio of the etching rate of the film/yttria film. The method for measuring an etching selectivity according to claim 13, wherein in the step of calculating the etching rate of the tantalum nitride film, the concentration and/or temperature of the etching liquid is measured while measuring the concentration and/or temperature. The etching rate of the tantalum nitride film was continuously calculated. The method for measuring an etching selectivity according to claim 13 includes an arithmetic processing for converting an etching rate of the yttrium oxide film coated on the crystal oscillator into a ratio when calculating a ratio of etching rates. The etching rate of the hafnium oxide film on the aforementioned substrate. The method for measuring an etching selectivity according to claim 13, comprising the step of calculating a cerium concentration in the etching liquid from the calculated etching rate of the cerium oxide film. An apparatus for measuring an etching selectivity ratio includes: a crystal oscillator that coats a ruthenium oxide film that contacts an etching liquid of a substrate processing apparatus; and an oscillation number detecting means that detects an oscillation frequency while oscillating the crystal oscillator; And the calculation means is to continuously calculate the etching rate of the tantalum nitride film/yttria film based on the etching rate of the hafnium oxide film calculated from the change in the oscillation frequency of the crystal oscillator and the etching rate of the tantalum nitride film. ratio. The apparatus for measuring an etching selectivity according to claim 17, further comprising at least one of a concentration measuring means for measuring a concentration of the etching liquid and a temperature measuring means for measuring a temperature of the etching liquid; In the calculation means, the tantalum nitride calculated based on the etching rate of the yttrium oxide film calculated from the change in the oscillation frequency of the crystal oscillator and the measured concentration and/or temperature of the etching liquid The etching rate of the film was used to continuously calculate the ratio of the etching rate of the tantalum nitride film/yttria film. The apparatus for measuring an etching selectivity according to claim 17, wherein the calculation means includes an arithmetic processing for converting an etching rate of a hafnium oxide film coated on the crystal oscillator when calculating a ratio of etching rates. The etching rate of the hafnium oxide film formed on the substrate. The apparatus for measuring an etching selectivity according to claim 17, wherein the calculation means further performs calculation processing for calculating a concentration of germanium in the etching liquid from the calculated etching rate of the tantalum oxide film. The apparatus for measuring an etching selectivity according to claim 17, further comprising a sensor head that liquid-tightly holds the crystal oscillator with a sealing member for pressing a periphery of the crystal oscillator And heating the aforementioned crystal oscillator by heat transfer from a heating means. The apparatus for measuring an etching selectivity according to claim 21, wherein the sensor head is provided inside the crystal oscillator with an internal space, and only the communication path is connected to the outside; and the valve member is disposed in the communication The path and the aforementioned communication path are blocked when the liquid flows into the aforementioned internal space.