JP5788546B2 - Hydroxyl radical-containing water supply device - Google Patents

Description

  The present invention relates to a hydroxyl radical-containing water supply apparatus.

  In recent years, with regard to hydroxyl radical-containing water used in silicon wafer cleaning processes and photoetching processes in the field of semiconductor material manufacturing, concentration management is indispensable from the viewpoints of product yield improvement, safety, work efficiency, etc. Concentration analysis is required.

  Further, not only in the field of manufacturing semiconductor materials, but also in fields such as food sterilization and washing and environmental pollutant decomposition, it is indispensable to control the concentration of hydroxyl radical-containing water with higher accuracy.

  Conventionally, in a TOC component removal method in which TOC component in TOC (total organic carbon) component-containing water is decomposed to an organic acid by hydroxyl radicals and ions are removed from the treated water, the TOC value of treated water after treatment with hydroxyl radicals There exists a TOC component removal apparatus that feedback-controls the amount of hydroxyl radicals generated (for example, Patent Document 1).

JP-A-11-057552

  However, since the TOC component removing device described in Patent Document 1 measures the TOC value and does not measure the hydroxyl radical concentration, whether or not the desired hydroxyl radical concentration is obtained as a result of feedback control. I can't know directly. For this reason, there is a problem that it is not possible to expect high-precision control of the hydroxyl radical concentration. On the other hand, electron spin resonance (ESR) can be used to measure the hydroxyl radical concentration. However, in ESR, a sample must be taken and measured, and not only can it be monitored at all times, but also is not suitable for use in a system that feeds back measurement results. Furthermore, as described above, in the field of manufacturing semiconductor materials and sterilizing and washing foods, it is expected that the concentration of hydroxyl radical-containing water generated for washing and the like can be measured with high accuracy.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to monitor the concentration of the generated hydroxyl radical-containing water with high accuracy, and preferably to enable hydroxyl concentration to be accurately controlled. The object is to provide a radical-containing water supply device.

In order to achieve the above object, the present invention provides the following.
That is, the hydroxyl radical-containing water supply device of the present invention includes a generating means for generating and supplying hydroxyl radical-containing water, and one or more wavelengths within the range of 140 to 210 nm of hydroxyl radical-containing water generated by the generating means. And a quantitative means for quantifying the hydroxyl radical concentration by measuring the light absorption characteristics of the sample.

  According to the above configuration, the hydroxyl radical concentration contained in the hydroxyl radical-containing water produced by the producing means for producing hydroxyl radical-containing water is quantified by the light absorption characteristics at one or more wavelengths within the range of 140 to 210 nm. It is possible to monitor the hydroxyl radical concentration directly in-line and with high accuracy.

  In the above configuration, it is preferable that a concentration adjusting unit that adjusts the hydroxyl radical concentration of hydroxyl radical-containing water generated by the generating unit based on the determination result of the hydroxyl radical concentration by the determining unit is provided. This is because the hydroxyl radical concentration can be set to a desired value in real time by adjusting the hydroxyl radical concentration of the generated hydroxyl radical-containing water based on the quantitative result of the hydroxyl radical concentration.

  In the above configuration, the quantification means includes a total reflection attenuation probe attached to a part of a wall surface made of an optical material of a storage tank for storing hydroxyl radical-containing water, and an incidence greater than a critical angle at an interface between the total reflection attenuation probe. A projection optical system that irradiates far ultraviolet light at an angle, and a light receiving optical system that receives reflected light totally reflected from the interface of the total reflection attenuation probe with a photodetector, and measures the total reflected light, It is preferable to quantify the hydroxyl radical concentration by determining the absorbance of hydroxyl radical-containing water.

  In the above configuration, a rotating stage in which an object to be cleaned is installed and hydroxyl radical-containing water is sprayed toward the object to be cleaned is provided, and the quantification unit is configured to receive hydroxyl radical-containing water from the rotating stage. A total reflection attenuating probe made of an optical material placed at the falling position, and a projection optics that irradiates far ultraviolet light generated by a light source to the interface of the total reflection attenuating probe with an incident angle larger than the critical angle. System and a light receiving optical system that receives reflected light totally reflected from the interface of the total reflection attenuating probe with a photodetector, and measures the total reflected light to obtain the absorbance of hydroxyl radical-containing water, It is also preferred to quantify the hydroxyl radical concentration.

  In the above configuration, an object to be cleaned is installed, a rotary stage is provided in which the hydroxyl radical-containing water is injected toward the object to be cleaned, and a pipe for transferring the hydroxyl radical-containing water to the injection port is provided. The quantification means includes a total reflection attenuating probe attached to a part of the pipe made of an optical material, and a projection optical that irradiates far ultraviolet light at an incident angle larger than a critical angle to the interface of the total reflection attenuating probe. System and a light receiving optical system that receives reflected light totally reflected from the interface of the total reflection attenuating probe with a photodetector, and measures the total reflected light to obtain the absorbance of hydroxyl radical-containing water, It is also preferred to quantify the hydroxyl radical concentration.

  In the above configuration, a hollow optical fiber is used for the light projecting optical system and the light receiving optical system, and one end of the optical fiber is positioned near the entrance surface and the exit surface of the total reflection attenuating probe. It is preferable that the air in the optical path is replaced with a gas that does not absorb the far ultraviolet light.

  In the above configuration, it is preferable that the optical material has a refractive index selected so that the penetration depth of the evanescent wave of the total reflected light is 150 nm or more in the measurement wavelength range of the far ultraviolet region.

  In the above configuration, the object to be cleaned is installed, and the rotation stage in which the hydroxyl radical-containing water is injected toward the object to be cleaned, the piping for transferring the hydroxyl radical-containing water to the injection port, and the piping A measurement cell provided in the middle, through which the hydroxyl radical-containing water passes, and the measurement means measures the light transmitted through the measurement cell in the far-ultraviolet region to determine the absorbance of the hydroxyl radical-containing water. It is also preferable to quantify the hydroxyl radical concentration by determining.

  In the above-described configuration, the generating means purifies ozone, hydrogen peroxide, at least one additive selected from the group consisting of a water-soluble organic substance, an inorganic acid, a salt of the inorganic acid, and hydrazine. It is preferable to dissolve in water to produce hydroxyl radical-containing water.

  In the said structure, it is preferable that the said hydroxyl radical containing water is supplied as a washing | cleaning liquid used in a semiconductor and liquid crystal manufacturing process.

  ADVANTAGE OF THE INVENTION According to this invention, the density | concentration of produced | generated hydroxyl radical containing water can be monitored with high precision, Preferably the hydroxyl radical containing water supply apparatus which makes it possible to perform density | concentration control accurately can be provided.

It is a block diagram which shows the structure of the hydroxyl radical containing water supply apparatus which concerns on one Embodiment of this invention. It is a flowchart which shows the control processing performed in the control apparatus shown in FIG. It is a graph of the wavelength dependence of the refractive index of various optical materials in the far ultraviolet region. It is a graph of the penetration depth of the evanescent wave to water on the total reflection surface of the quartz probe. It is a graph of the penetration depth of the evanescent wave to water at the total reflection surface of the sapphire probe. It is a graph of the light absorbency of water measured using the quartz ATR probe and the sapphire ATR probe. It is a graph of the light absorbency of the aqueous solution of NaI measured using the quartz ATR probe and the sapphire ATR probe. It is a figure of the semiconductor cleaning system used for a batch type cleaning method. It is a figure of the optical measurement part provided in the inside of a density | concentration measurement part. It is a figure of the hydroxyl radical containing water supply apparatus in a single wafer type semiconductor cleaning system. It is a figure which shows other embodiment of the hydroxyl radical containing water supply apparatus in a single wafer type semiconductor cleaning system. It is a figure of a part of optical system using the optical fiber of a hollow structure. It is a figure of a part of optical system using the optical fiber of a hollow structure. It is a figure which shows other embodiment of the hydroxyl radical containing water supply apparatus in a single wafer type semiconductor cleaning system.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a block diagram showing a configuration of a hydroxyl radical-containing water supply device according to an embodiment of the present invention. The hydroxyl radical-containing water supply device 120 according to the present embodiment is produced by dissolving hydroxyl radical-containing water (hereinafter also referred to as “radical water”) by dissolving ozone, hydrogen peroxide, and a specific chemical in pure water. To do. Then, the concentration of the generated radical water is monitored by the radical monitor 136, and ozone, hydrogen peroxide, and hydroxyl radicals are generated according to the obtained hydroxyl radical concentration (hereinafter also referred to as "radical concentration"). Adjust the supply of specific drugs that contribute to the promotion. Thereby, the density | concentration of hydroxyl radical containing water can be made into a desired value with real time and high precision.

  As shown in FIG. 1, the hydroxyl radical-containing water supply device 120 includes an ozone generator 122, an ozone dissolving device 124, a drug adding device 126, a hydrogen peroxide adding device 128, a drug concentration meter 130, and an ozone concentration. A total 132, a storage tank 134, a radical monitor 136, and a control device 138 are provided.

  The ozone generator 122 is connected to an oxygen cylinder (not shown), and converts the oxygen gas 140 from the oxygen cylinder into ozone gas. As the ozone generator 122, for example, a general-purpose water-cooled ozone generator, a silent discharge ozone generator, or the like can be used.

  The ozone dissolving device 124 is connected to the pipe L1 to which the pure water 142 is transferred, and is also connected to the ozone generating device 122, and the ozone generated by the ozone generating device 122 is dissolved in the pure water 142 to generate ozone water. Is generated.

  The chemical addition device 126 is connected to a pipe L2 to which the ozone water generated by the ozone dissolving device 124 is transferred, and adds a specific chemical to the ozone water. The specific medicine will be described later.

  The hydrogen peroxide addition device 128 is connected to the downstream side of the chemical addition device 126 in the pipe L2, and further adds hydrogen peroxide to the ozone water to which the chemical is added. As a result, hydroxyl radicals are generated, and hydroxyl radical-containing water is obtained. And the obtained hydroxyl radical containing water is accommodated in the storage tank 134 connected to the downstream end part of the piping L2. Although it does not specifically limit as the storage tank 134, For example, when using the hydroxyl radical containing water supply apparatus 120 as a supply apparatus of the washing | cleaning liquid (radical water) of a silicon wafer, it is a washing tank and is the decomposition liquid ( When used as a supply device for radical water), it is a decomposition tank.

  The drug concentration meter 130 is connected to the downstream side of the drug addition device 126 in the pipe L <b> 2, measures the drug concentration in ozone water, and transmits data indicating the measured drug concentration to the control device 138. In addition, the ozone concentration meter 132 is connected to two locations of the pipe L2 upstream of the hydrogen peroxide addition device 128 and downstream of the hydrogen peroxide addition device 128. The ozone concentration meter 132 measures the initial ozone concentration on the upstream side of the hydrogen peroxide addition device 128 and measures the final ozone concentration on the downstream side. Then, the ozone concentration meter 132 transmits data indicating the initial ozone concentration and data indicating the final ozone concentration to the control device 138. The initial ozone concentration refers to the ozone concentration before the addition of hydrogen peroxide, and the final ozone concentration refers to the ozone concentration before being stored in the storage tank 134 after the addition of hydrogen peroxide.

  The radical monitor 136 measures the hydroxyl radical concentration of the hydroxyl radical-containing water stored in the storage tank 134, and transmits data indicating the measured hydroxyl radical concentration to the control device 138. The concentration measurement by the drug concentration meter 130, the ozone concentration meter 132, and the radical monitor 136 is performed continuously or intermittently and is transmitted to the control device 138 each time it is measured.

  The control device 138 includes a central processing unit and a memory, as well as a radical monitor 136, an ozone generator 122, an ozone dissolving device 124, a drug adding device 126, a hydrogen peroxide adding device 128, a drug concentration meter 130, and ozone. A densitometer 132 is connected to control the operation of these devices. For example, the control device 138 determines the amount of ozone gas generated from the ozone generator 122, the amount of drug added from the drug addition device 126 based on the data received from the radical monitor 136, the drug concentration meter 130, and the ozone concentration meter 132, Then, the amount of hydrogen peroxide added from the hydrogen peroxide adding device 128 is adjusted. Hereinafter, processing executed by the control device will be described with reference to flowcharts.

  FIG. 2 is a flowchart showing a control process performed in the control device shown in FIG. First, the control device 138 determines whether or not the radical concentration value received from the radical monitor 136 is within the set radical concentration value range (step S10). If it is determined that the received hydroxyl radical concentration value is within the set radical concentration value range (step S10: YES), the process returns to step S10. On the other hand, if it is determined that the received radical concentration value is not within the set radical concentration value range (step S10: NO), the process proceeds to step S12.

  In step S12, the control device 138 determines whether or not the initial ozone concentration value received from the ozone concentration meter 132 is within the set initial ozone concentration value range. If it is determined that the received initial ozone concentration value is within the set initial ozone concentration value range, the process proceeds to step S16. On the other hand, when it is determined that the received initial ozone concentration value is not within the set initial ozone concentration value range (step S12: NO), the control device 138 transmits an ozone concentration adjustment command to the ozone generator 122, thereby Processing for adjusting the amount of ozone generated by the generator 122 is performed (step S14). After the process of step S14, the process returns to step S10.

  In step S16, the control device 138 determines whether or not the drug concentration value received from the drug concentration meter 130 is within the set drug concentration range. If it is determined that the received drug concentration value is within the set drug concentration value range, the process proceeds to step S20. On the other hand, when it is determined that the received initial ozone concentration value is not within the set initial ozone concentration value range (step S16: NO), the control device 138 transmits a drug concentration adjustment command to the drug concentration meter 130, thereby A process of adjusting the amount of drug added by the densitometer 130 is performed (step S18). After the process of step S18, the process returns to step S10.

  In step S20, the control device 138 determines whether or not the final ozone concentration value received from the ozone concentration meter 132 is larger than the set final ozone concentration value. When it is determined that the final ozone concentration value received from the ozone concentration meter 132 is not larger than the set final ozone concentration value (step S20: NO), the control device 138 issues a hydrogen peroxide addition amount reduction command to the hydrogen peroxide addition device. By transmitting to 118, the amount of hydrogen peroxide added is decreased (step S22). Thereby, decomposition | disassembly of ozone will be suppressed. On the other hand, when it is determined that the final ozone concentration value received from the ozone concentration meter 132 is larger than the set final ozone concentration value (step S20: YES), the control device 138 issues a hydrogen peroxide addition amount increase command to add hydrogen peroxide. By transmitting to the apparatus 118, the amount of hydrogen peroxide added is increased (step S24). Thereby, decomposition | disassembly of ozone will be accelerated | stimulated. After the process of step S22 or step S24, the process returns to step S10.

  Thus, according to the hydroxyl radical-containing water supply device 120, when the hydroxyl radical concentration is not within a certain range (step S10: NO), the initial ozone concentration, the chemical concentration, and the final ozone concentration are adjusted (step). S14, step S18, step S22, step S24), and the hydroxyl radical concentration can be set to a desired value in real time and with high accuracy.

  The ozone generator 122, the chemical addition device 116, and the hydrogen peroxide addition device 118 correspond to the generation means for generating hydroxyl radical-containing water according to the present invention. The radical monitor 136 corresponds to the quantification means of the present invention. Further, when executing the processing of step S14, step S18, step S22, and step S24, the control device 138 functions as the density adjusting means of the present invention.

  Here, the generation method of radical water in the above-described embodiment will be described in detail. In the above-described embodiment, the radical water is generated by dissolving ozone, hydrogen peroxide, and a specific chemical in pure water. As a result of the inventors' diligent research, this radical water generation method generates hydroxyl radicals with relatively high efficiency when ozone, hydrogen peroxide, and a specific drug are dissolved in pure water. The invention has been completed by finding that the concentration can be maintained for about several minutes. According to this method, it is possible to generate hydroxyl radicals with relatively high efficiency simply by dissolving ozone, hydrogen peroxide, and a specific agent in pure water without using equipment such as ultraviolet irradiation equipment. it can.

  As said specific chemical | medical agent, a water-soluble organic substance, an inorganic acid, the salt of the said inorganic acid, and hydrazine can be mentioned, These are good also as using individually or 2 types or more. .

First, the case where a water-soluble organic substance is employed as the specific drug will be described. When ozone, hydrogen peroxide, and water-soluble organic substances are present in water, it is considered that hydroxyl radicals are generated based on the reaction formula shown below.
First, hydroxyl radicals are generated from ozone and hydrogen peroxide (Formula 1). Since hydroxyl radicals have a short lifetime, they immediately disappear, but when water-soluble organic substances are present, hydroxyl radicals cause a chain reaction with water-soluble organic substances (Formula 2).
Furthermore, a hydroxyl radical is generated by the organic radical (R ·) generated by this chain reaction and hydrogen peroxide (Formula 3).

Reaction formula;
Hydroxyl radical generation by reaction of ozone and hydrogen peroxide (Formula 1)
O ₃ + H ₂ O ₂ → OH · + HO ₂ + O ₂
H ₂ O ₂ ⇔ HO ₂ ⁻ + H ⁺
O ₃ + HO ₂ ⁻ → OH · + O ₂ ⁻ · + O ₂
Chain reaction with organic matter (Formula 2)
RH + OH · → R · + H ₂ O
R ・ + O ₂ → RO ₂・
RO ₂・ + RH → ROOH + R ・
RO ₂・ + HO ₂・ → RO ・ + O ₂ + OH ・
Production by decomposition of hydrogen peroxide (Equation 3)
H ₂ O ₂ + R · → HOR + OH ·

  As the water-soluble organic substance, an ozone reaction rate constant of 10 L / mol / sec or less, particularly 1.0 L / mol / sec or less, preferably 0.001 to 1.0 L / mol / sec is used from the viewpoint of hydroxyl radical generation. Is done. The ozone reaction rate constant is a reaction rate constant at the time of reaction with ozone. The smaller the ozone reaction rate constant, the more difficult it is to react with ozone. By using the water-soluble organic substance having a relatively small ozone reaction rate constant as described above, it is possible to contribute to the promotion of the hydroxyl radical-generating reaction by the water-soluble organic substance without inhibiting the generation of the hydroxyl radical by ozone. The ozone reaction rate constants of various compounds can be found from known literature, for example, Table 2 in “Ozone treatment and hydroxyl radical” (written by Shigeki Nakayama) published by the 4th “Ozone radical sterilization and deodorization study group”. .2 “Reaction rate constants of ozone and OH radicals and compounds in water”.

  Examples of such water-soluble organic substances include alcohols such as methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, and t-butanol, acetone, acetic acid, formic acid, citric acid, and the like. .

  Among the above water-soluble organic substances, those having a relatively low boiling point are preferably used from the viewpoint of use as cleaning water for radical water electronic components and the like. For example, n-propanol, iso-propanol, n-butanol, iso- Examples include butanol and t-butanol. The most preferred water-soluble organic substance is iso-propanol (isopropanol).

Next, a case where an inorganic acid is employed as the specific drug will be described.
Examples of the inorganic acid or the salt of the inorganic acid include hydrochloric acid, sulfuric acid, carbonic acid, carbonate, hydrogen carbonate, nitrous acid, nitrite, sulfite, sulfite, hydrogen sulfite, and hydrofluoric acid. Among these, carbonic acid is preferable because it can be volatilized as carbon dioxide gas after using radical water.

When ozone, hydrogen peroxide, and carbonic acid are present in water, it is considered that hydroxyl radicals are generated based on the reaction formula shown below.
First, hydroxyl radicals are generated from ozone and hydrogen peroxide (Formula 4). Hydroxyl radicals disappear immediately because of their short lifetime, but in the presence of carbonic acid, the hydroxyl radical causes a chain reaction with carbonic acid (Formula 5).
Furthermore, hydroxyl radicals are generated by hydroperxyl radicals (HO _2. ) Generated by the reaction between carbonic acid and hydrogen peroxide and ozone (formula 6).

Reaction formula;
Hydroxyl radical generation by the reaction of ozone and hydrogen peroxide (Formula 4)
O ₃ + H ₂ O ₂ → OH · + HO ₂ + O ₂
H ₂ O ₂ ⇔ HO ₂ ⁻ + H ⁺
O ₃ + HO ₂ ⁻ → OH · + O ₂ ⁻ · + O ₂
Chain reaction with carbonic acid (Formula 5)
CO ₂ + H ₂ O⇔HCO ₃ ⁻ + H ⁺
HCO ₃ ⁻ ⇔ CO ₃ ²⁻ + H ⁺
CO ₃ ²⁻ + OH · → CO ₃ ⁻ · + OH ⁻
CO ₃ ⁻ · + OH · → CO ₂ + HO ₂ ⁻
O ₃ + HO ₂ ⁻ → OH · + O ₂ ⁻ · + O ₂
Hydroxyl radical formation by hydroperxyl radical and ozone generated by the reaction of carbonic acid and hydrogen peroxide (Formula 6)
CO ₂ + H ₂ O⇔HCO ₃ ⁻ + H ⁺
HCO ₃ ⁻ ⇔ CO ₃ ²⁻ + H ⁺
CO ₃ ²⁻ + OH · → CO ₃ ⁻ · + OH ⁻
CO ₃ ⁻ · + H ₂ O ₂ → HCO ₃ ⁻ + HO ₂ ·
^{_{HO 2 · ⇔ + O 2 -}} · + H +
O ₂ ⁻ · + O ₃ → O ₃ ⁻ · + O ₂
O ₃ ⁻ · + H ₂ O → OH · + O ₂ + OH ⁻

  Pure water is water from which impurities have been removed, and usually water having an electrical resistivity of 15 MΩ · cm or more is used. From the viewpoint of using radical water as a cleaning liquid for electronic parts, semiconductors, liquid crystal related parts and the like (hereinafter referred to as electronic parts), ultrapure water having an electric resistivity of 17 MΩ · cm or more is preferably used. The electrical resistivity can be measured using a commercially available specific resistivity meter.

  The radical water generation method according to this embodiment has been described above. In the present invention, the method for generating radical water is not limited to the above-described method. For example, by irradiating ultraviolet rays using a UV irradiation device to pure water added with ozone and a specific agent, The method of producing | generating radical water can be mentioned. In this case, the ozone generation device, the chemical addition device, and the ultraviolet irradiation device correspond to the generation means of the present invention. In addition to the above, a conventionally known method may be employed as a method for generating radical water, for example, a method of simply irradiating ultraviolet rays to ozone without using a specific agent, or irradiating hydrogen peroxide to ultraviolet rays. Or a method of irradiating hypochlorous acid with ultraviolet rays.

  For the radical monitor 138 described above, for example, a measuring device using the method for measuring an aqueous solution (JP-A-2005-214863) previously invented by the present inventors can be used.

The method for measuring an aqueous solution disclosed in Japanese Patent Application Laid-Open No. 2005-214863 is based on the bottom part of the absorption peak of the absorption peak of water (n → σ ^* transition absorption band of water molecules) appearing in the far ultraviolet region (for example, This is a method for measuring absorption of far ultraviolet rays at 170 to 210 nm). This absorption spectrum correlates with the concentration of charged dissolved components dissolved in water (for example, cations such as sodium ions and potassium ions and anions such as chloride ions and nitrate ions). However, the present inventors have also found that this absorption spectrum correlates with the hydroxyl radical concentration for hydroxyl radicals dissolved in water. Therefore, by utilizing this method, quantitative measurement of hydroxyl radicals in an aqueous solution can be performed with high sensitivity.

  Further, the radical monitor 138 described above is disclosed in the total reflection attenuation type far-ultraviolet spectroscopic device invented by the present inventors (for example, Japanese Patent Application Laid-Open No. 2007-279025 and Japanese Patent Application Laid-Open No. 2008-224240). It is also possible to use a total reflection attenuation type far ultraviolet spectrometer. The water absorption band has a very high absorbance, so when measuring with a transmission spectrum, it is necessary to make the cell length as short as possible. According to the type far-ultraviolet spectroscopic apparatus, an absorption spectrum similar to a transmission spectrum due to a cell length in the wavelength order can be obtained theoretically, and therefore, it can be preferably used.

  Here, a little more explanation of total reflection attenuation absorption will be given. When a light beam hits an interface between a medium having a higher refractive index (for example, synthetic quartz) and a medium having a lower refractive index (a sample to be measured, for example, water) from the medium side having a higher refractive index, the incident angle θ is If it is larger than the critical angle, the light beam is totally reflected. However, the light beam penetrates into a medium having a lower refractive index by a certain distance on the order of the wavelength, travels toward the interface, and is then reflected. The light rays that enter the medium having a lower refractive index are called evanescent waves. The electric field intensity of the evanescent wave is maximum at the reflection point, and is attenuated immediately in the interface direction and the direction perpendicular to the interface. The distance at which the electric field intensity of the evanescent wave attenuates to 1 / e is called the penetration depth. According to the total reflection attenuation absorption method, the absorption of light with respect to the penetration of light of the wavelength order (evanescent wave) formed when the light is totally reflected can be measured from the reflected light. Since the light penetration depth corresponds to the optical path length of a normal transmission spectrum, a very small cell length can be realized, and an absorption spectrum that is theoretically similar to a transmission spectrum with a cell length in the wavelength order can be obtained.

The total reflection attenuation probe provided in the attenuated total reflection type far ultraviolet spectrometer disclosed in Japanese Patent Application Laid-Open No. 2007-279025 is an optical probe (prism) for measuring the n → σ ^* transition absorption band of water in the far ultraviolet region. The total reflection attenuating probe has a special structure based on the total reflection condition that the refractive index of the material is greater than the refractive index of the sample substance and the transmission condition that the light transmittance of the optical probe material is sufficiently high in the measurement wavelength region. It is proposed as a probe having a three-layer structure.

  Here, when comparing sapphire and quartz, which are typical materials for the total reflection attenuation probe in the ultraviolet region (see FIG. 3), sapphire has a higher refractive index than water in the entire wavelength range. In contrast, quartz has a refractive index lower than that of water in the wavelength range near 160 nm and does not cause total reflection, so it cannot be used as a total reflection attenuation probe.

  However, when using a total reflection attenuating probe to measure the concentration of the cleaning solution in a semiconductor cleaning treatment tank, the total reflection attenuating probe must be made of a material that does not elute or erode in the sample. In this case, the refractive index is always higher than that of the sample and limited to those having sufficient transmittance. Therefore, the material applicable to the total reflection attenuation probe is limited to high-purity synthetic quartz.

  Therefore, in order to apply the total reflection attenuation absorption method to the measurement of the component concentration of the cleaning liquid used in the semiconductor cleaning process, the present inventors have studied the depth of penetration of the total reflection attenuation probe for far ultraviolet using synthetic quartz. For optimization, we selected the incident angle condition of the measurement light and the selection of the measurement wavelength region by trial and error and succeeded in obtaining the absorption data. As a result, the present inventors have invented an attenuated total reflection type far-ultraviolet spectroscopic device that can measure a minute component concentration in an aqueous solution without using the total reflection attenuation probe having the special structure described above. In this attenuated total reflection type far-ultraviolet spectroscope, the material of the total reflection attenuation probe is made of a material whose refractive index is very close to that of the object to be measured (aqueous solution), and the depth of penetration of the evanescent wave of the total reflected light is positively determined. Extend and measure far ultraviolet absorption. As described above, the attenuated total reflection type far-ultraviolet spectroscopic device described below can be suitably used as the radical monitor 136 when used in a semiconductor cleaning process. This will be described below.

The penetration depth d _p of the evanescent wave at the interface of the total reflection attenuation probe (hereinafter also referred to as “ATR probe”) is the wavelength λ, the incident angle θ, and the refraction of the probe material as shown in the following equation (1). It is calculated from the refractive index n ₁ and the refractive index n ₂ of the measurement target (water).

全反射は臨界角以上の入射角θで起こる。

Total reflection occurs at an incident angle θ greater than the critical angle.

図４は、石英プローブにおける光の測定対象（水）への潜り込み深さの計算結果に示す。ここで、入射角θが６８度、７０度、７２度、７４度である場合のデータを示している。

FIG. 4 shows the calculation result of the penetration depth of light into the measurement target (water) in the quartz probe. Here, data when the incident angle θ is 68 degrees, 70 degrees, 72 degrees, and 74 degrees are shown.

In quartz, the refractive index n ₂ is smaller than the refractive index n _{1 of} water at around 160 nm (see FIG. 1). Therefore, when the incident angle θ is 75 degrees or more, light on the shorter wavelength side than 168 nm is transmitted without being totally reflected. As a result, the absorbance of the measurement target cannot be measured. However, as shown in FIG. 4, the penetration depth of the evanescent wave increases to several hundred nm or more at a wavelength near 170 nm, which is the boundary of the total reflection condition. For this reason, the water absorption band is enlarged and observed around 170 nm by ATR measurement. The vicinity of 170 nm is an inclined portion of the n → σ ^* transition absorption band of water, and the absorbance changes depending on the concentration of the dissolved component contained in the aqueous solution. Therefore, the ATR measurement near 170 nm is performed in the aqueous solution. It can be used for quantitative determination of the component concentration. Conventionally, there has been no attempt to enlarge and observe the bottom part of the far-ultraviolet absorption spectrum of water by actively utilizing the wavelength region that becomes the boundary of the total reflection condition. However, the study of optimization of the penetration depth in consideration of the total reflection condition has revealed that it can be applied to quantitative measurement of dissolved components in an aqueous solution. Therefore, when using synthetic quartz as an ATR probe and measuring an aqueous solution, the refractive index of synthetic quartz and the refractive index of water are close to each other near the water absorption peak. The total reflected light can be measured at 150 nm or more in the measurement wavelength range of the far ultraviolet region, whereby the absorbance can be measured with high sensitivity. At this time, the measurement wavelength range is approximately 170 to 175 nm.

  In addition, even in the region of 175 to 300 nm where the probe material (quartz) and the refractive index of the measurement object are not close compared to around 170 nm, the depth of the total reflected light is about 100 nm because the difference in refractive index is still small. Yes, the absorbance can be measured with a spectrophotometer. Therefore, the absorption of the solute itself can be observed if it is in this wavelength range. Since the extinction coefficient of the aqueous solution in the far ultraviolet region of 170 to 300 nm is very large, sufficient measurement sensitivity can be obtained even using the ATR method. Therefore, the same measurement as the transmission measurement of the aqueous solution described in Japanese Patent Application Laid-Open No. 2005-214863 can be performed for the total reflected light using the ATR probe.

  For comparison, FIG. 5 shows the calculation result of the depth of penetration of light into the water in the sapphire probe when the incident angle is in the range from 56 degrees to 66 degrees. The depth of penetration is 70 nm or less in the far ultraviolet region. In the case of the sapphire material, since the difference in refractive index between the probe material and the object to be measured is large, ATR measurement is possible in the entire far ultraviolet wavelength region, but the depth of penetration is less than 100 nm.

FIG. 6 shows the absorbance of water measured using a quartz ATR probe and a sapphire ATR probe. Originally, the absorption peak of the n → σ ^* transition absorption band of water is around 150 nm, and when the material of the ATR probe is a high refractive index material such as sapphire, no water absorption band is observed around 170 nm. However, when the probe material is synthetic quartz, the depth of penetration of the evanescent wave becomes very large in the region where the refractive index is close to the refractive index of water. The absorption band is enlarged and observed.

  FIG. 7 shows the absorbance in the far ultraviolet region of an aqueous solution of NaI measured using a quartz probe and a sapphire probe. In the figure, a range surrounded by two arrows indicates a wavelength range in which total reflection does not occur. Here, the peak near 230 nm is a peak due to absorption by the solute (NaI). The concentration of NaI in the sample is 0, 20, 40, 60, 80, 100 mM. For sapphire, only pure water is shown, but absorption by NaI is also observed. However, since the peak is low, illustration is omitted.

  In the above, the measurement of the aqueous solution using quartz as the material of the ATR probe has been described. In general, the ATR probe is made of an optical material whose refractive index is very close to the refractive index of the object to be measured. It is possible to perform far ultraviolet spectroscopic measurement by actively extending the penetration depth of the light evanescent wave. In other words, the penetration depth of the evanescent wave of the total reflection light is the wavelength of the far ultraviolet light, the refractive index of the sample, the refractive index of the optical material of the total reflection attenuation probe, and the incidence of the ultraviolet light at the probe-sample interface. Although it is determined by the angle, when an optical material having a refractive index very close to the refractive index of the measurement target can be used, the optical material of the ATR probe, the measurement wavelength, and the Select the angle of incidence. Using a total reflection attenuation probe made of an optical material having such a refractive index, the sample is brought into contact with the interface of the total reflection attenuation probe. Then, far-ultraviolet light is incident on the interface at an incident angle greater than the critical angle and the above measurement wavelength so that the penetration depth is 150 nm or more. Then, the total reflected light from the interface is measured to determine the absorbance of the sample.

  Next, the case where the above-described measurement method is applied to the management of the hydroxyl radical concentration of the semiconductor cleaning system will be described. FIG. 8 shows the cleaning tank 1 used for the batch cleaning method. The cleaning tank 1 is made of synthetic quartz and contains a cleaning liquid 7 that is hydroxyl radical-containing water. A plurality of wafers 2 (objects to be cleaned) are installed in the cleaning tank 1 and immersed in the cleaning liquid 7. Here, for example, four concentration measuring units 3, 4, 5, and 6 are installed on the side surface of the cleaning tank 1. The concentration measuring unit including the ATR probe can be installed anywhere on the wall surface of the cleaning tank 1. Thereby, the concentration of the cleaning liquid 7 in the cleaning tank 1 can be checked in real time without taking the cleaning liquid out of the cleaning tank 1. The concentration distribution variation of the cleaning liquid 7 in the cleaning tank 1 can be checked by installing in a plurality of locations.

  FIG. 9 shows an optical measurement unit provided inside the density measurement unit (attenuated total reflection type far-ultraviolet spectrometer) 3, 4, 5 and 6. Similar to the wall 22 of the processing tank, the ATR probe 21 made of synthetic quartz is directly fixed to the wall 22 of the cleaning tank and integrated with the wall 22 of the cleaning tank. Light generated from an ultraviolet light source (for example, a deuterium lamp) 23 is collimated by a light projection lens 26, reflected by a diffraction grating 24, which is a monochromator, and further passes through a light projection lens 27 to the ATR probe 21. Incident. These constitute a light projecting optical system for irradiating the ATR probe 21 with light. The incident angle to the optical probe 21 is set to an appropriate value. The totally reflected light from the optical probe 21 passes through the light receiving lens 28 and enters the photodetector (ultraviolet light sensor) 25. These constitute a light receiving optical system in which reflected light emitted from the ATR probe 21 is received by the photodetector 25. Further, a sealed structure (housing) 31 is provided for sealing the optical system in order to replace nitrogen in the light incident / exit end face of the ATR probe 21 and the air in the light projecting / receiving optical system portion with nitrogen. In this sealed structure, nitrogen gas that does not absorb in the far ultraviolet region is introduced from the inlet 29 and discharged from the outlet 30, and thus oxygen gas is excluded from the optical system. (Air replacement with argon gas may be used, or the air itself is evacuated to a vacuum.) The spectrum detected by the photodetector 25 is processed by an external signal processing unit (not shown). Then, the absorbance is calculated based on the measurement data. Here, a calibration curve can be created by known multivariate analysis for absorbance at a plurality of wavelengths. Measurement can be performed in real time using this calibration curve. Thereby, the density | concentration of the washing | cleaning liquid in the washing tank 22 can be directly measured using this measuring apparatus. In this measuring apparatus, since synthetic quartz is used as the material of the probe 21 in the same manner as the wall 2 of the processing tank, the problem that impurities are eluted from the probe 21 during the process or the probe 21 itself is eroded by the cleaning liquid is solved. it can. In addition, since the measurement ultraviolet light acts on a very small part of the sample material in contact with the interface of the probe, the sample change due to ultraviolet light irradiation can be substantially avoided.

  FIG. 10 shows a hydroxyl radical-containing water supply device in a single wafer type semiconductor cleaning system. In the case of a single sheet type, an ATR probe is installed beside a silicon wafer rotation stage (rotation table) so that the cleaning liquid falling from the wafer when the liquid is ejected falls on the ATR probe. Specifically, the cleaning liquid 42 is sprayed from the cleaning nozzle 41 located above the wafer rotation stage 44 (spray) onto the wafer 43 placed on the wafer rotation stage 44. The cleaning liquid 46 sprayed toward the wafer 43 falls outside from the outer peripheral direction by the action of centrifugal force generated by the rotation of the wafer rotation stage 44. Here, a concentration measuring unit 45 having the same configuration as that of the concentration measuring unit 3 shown in FIG. In the concentration measurement unit 45, the ATR probe 1 is positioned with the interface with the cleaning liquid facing upward. The absorbance of the cleaning liquid that has fallen from the wafer rotation stage 44 onto the ATR probe of the concentration measurement unit 45 is measured.

  FIG. 11 shows another embodiment of the hydroxyl radical-containing water supply device in the single wafer semiconductor cleaning system. In the hydroxyl radical-containing water supply apparatus shown in FIG. 11, the concentration measuring unit 47 having the same configuration as that of the concentration measuring unit 3 shown in FIG. 9 is not located next to the rotation stage of the silicon wafer (see FIG. 10), but the cleaning liquid. Is installed on a pipe L3 that transfers the water to the cleaning nozzle 41 (corresponding to the injection port of the present invention). A part of the pipe L3 is made of the optical material described above, and the ATR probe 21 of the concentration measuring unit 47 is directly fixed to the optical material part of the pipe L3 and integrated with the wall surface of the pipe L3. . Then, in the concentration measuring unit 47, the absorbance of the cleaning liquid transferred through the pipe L3 is measured. The installation position on the pipe L3 of the concentration measuring unit 47 is preferably immediately before the cleaning nozzle 41, and specifically, a position where hydroxyl radical-containing water from 0 to 300 seconds before being injected from the injection port can be measured. What is necessary is just to set it as the position which can measure the hydroxyl radical containing water of 0-10 seconds ago, and it is still more preferable to set it as the position which can measure 0.1-1 second before hydroxyl radical containing water. This is because the hydroxyl radical-containing water concentration from 0 to 300 seconds before injection from the injection port can be regarded as the concentration at the time of use (in the present embodiment, at the time of cleaning). In addition, the piping L3 is corresponded to the piping which transfers the hydroxyl radical containing water of this invention to a jet nozzle.

  Further, for example, a hollow optical fiber may be used for the light projecting / receiving optical system, and the air in the optical path in the optical fiber may be replaced with nitrogen or argon. Since a hollow optical fiber is used, as shown in FIGS. 12 and 13, the optical system can be separated into two parts connected by the optical fiber. 12 and 13 show an example in which the ATR probe 61 is provided on the wall surface 62 of the pipe for introducing the spray liquid. The ATR probe 61 is hemispherical. Incident light 63 from the hollow optical fiber (projecting side) 65 enters the interface with the cleaning liquid of the ATR probe 61, is totally reflected and enters the hollow optical fiber (light receiving side) 65 'as reflected light. The optical fibers 65 and 65 ′ are installed corresponding to the incident angle of light. On the other hand, the other part of the optical system is provided in a sealing structure (housing) shown in FIG. The far ultraviolet light generated from the light source 66 is reflected by the diffraction grating 67 and enters the hollow optical fiber (projecting side) 65. The reflected light from the hollow optical fiber (light receiving side) 65 ′ is reflected by the mirror 68 and detected by the photodetector 69. Further, in order to exclude oxygen gas in the sealed structure, nitrogen gas that does not absorb in the far ultraviolet region is introduced from the inlet 70 and enters the hollow portions of the optical fibers 65 and 65 ′. And it goes out from the edge part shown by FIG.

  In addition, although the structure of various deep ultraviolet measuring apparatuses is shown by FIGS. 9-13, the component contained in them can be combined. For example, the hollow optical fibers shown in FIGS. 12 and 13 can also be used in the structures of FIGS.

  FIG. 14 shows another embodiment of the hydroxyl radical-containing water supply device in the single wafer semiconductor cleaning system. This hydroxyl radical-containing water supply apparatus is an apparatus that utilizes the method for measuring an aqueous solution (JP-A-2005-214863) invented so far by the present inventors. As shown in FIG. 14, a transmittance measuring cell 50 through which hydroxyl radical-containing water passes is provided in the middle of a pipe L <b> 3 for transferring the cleaning liquid to the cleaning nozzle 41. Further, the hydroxyl radical-containing water supply device includes an ultraviolet light source unit 51, a light receiving unit 52, and a signal processing unit 53. The ultraviolet rays emitted from the ultraviolet light source 41 include at least a part of the wavelength in the far ultraviolet region (100 nm to 280 nm), and pass through the transmittance measuring cell 50 and the cleaning liquid passing therethrough. The light that has passed through the transmittance measuring cell 50 and the cleaning liquid enters the light receiving section 52 and is split into a plurality of wavelengths. The signal processing unit 53 calculates the signal at each measurement wavelength and quantifies the concentration. As this apparatus, a conventional spectroscopic apparatus capable of measuring at a wavelength of 190 nm to 280 nm can be used. For example, an ultraviolet / visible spectroscopic analyzer 3100PC manufactured by Shimadzu Corporation can be used.

  In the present invention, the radical concentration can be calculated from the obtained absorbance by the radical monitor 136 (for example, the above-mentioned total reflection attenuation type far-ultraviolet spectroscopic device), and the absorbance transmitted from the radical monitor 136 can be calculated. The control device 138 may calculate based on the data shown. When the radical monitor 136 calculates the radical concentration, the calculation result is transmitted from the radical monitor 136 to the control device 138. Further, based on the measured absorbance of radical water without calculating the radical concentration, the radical concentration is adjusted (for example, adjustment of the amount of ozone gas generated from the ozone generator 122, adjustment of the amount of drug added from the drug addition device 126). Further, adjustment of hydrogen peroxide added from the hydrogen peroxide adding device 128 may be performed. This method is also included in the adjustment of the hydroxyl radical concentration of hydroxyl radical-containing water generated based on the quantitative result of the hydroxyl radical concentration of the present invention.

  In the above-described embodiment, the case where the hydroxyl radical-containing water supply device of the present invention is applied to a semiconductor cleaning system has been described. However, the hydroxyl radical-containing water supply device of the present invention is not limited to this example. The apparatus which supplies the hydroxyl radical containing water as a process liquid used at a process etc. may be sufficient. Further, the hydroxyl radical-containing water supply device of the present invention is not limited to the field of manufacturing semiconductor materials as described above, and may be used in the field of manufacturing liquid crystal display devices, etc. It may be used in the field of decomposition processing.

  The embodiment of the present invention has been described above, but only specific examples are illustrated, and the present invention is not particularly limited. The specific configuration of each unit and the like can be appropriately changed. The effects described in the embodiments of the present invention are only the most preferable effects resulting from the present invention, and the effects of the present invention are limited to those described in the embodiments of the present invention. is not.

DESCRIPTION OF SYMBOLS 1 Cleaning tank 2 Wafer 3, 4, 5, 6 Concentration measurement part 7 Cleaning liquid 22 Wall surface 21 of a processing tank ATR probe 22 Wall surface 23 of a cleaning tank Ultraviolet light source 24 Diffraction grating 25 Light detector 26 Projection lens 27 Projection lens 28 Light reception Lens 29 N ₂ gas inlet 30 N ₂ gas outlet 31 Sealing structure 41 Cleaning nozzle 42 Cleaning liquid 43 Wafer 44 Wafer rotation stage 45, 47 Concentration measuring unit 46 Cleaning liquid 50 Transmittance measuring cell 61 ATR probe 62 Piping wall surface 65, 65 ′ Hollow optical fiber 66 Light source 67 Diffraction grating 68 Mirror 69 Photo detector 70 N ₂ gas inlet 120 Hydroxyl radical-containing water supply device 122 Ozone generator 124 Ozone dissolution device 126 Drug addition device 128 Hydrogen peroxide addition device 130 Drug concentration meter 132 Ozone Densitometer 134 Containment tank 136 Radical monitor 138 140 oxygen gas 142 pure L1, L2, L3 pipe

Claims (1)

Hydroxyl radical-containing water by dissolving ozone, hydrogen peroxide, water-soluble organic substance, inorganic acid, salt of inorganic acid, and at least one additive selected from the group consisting of hydrazine in pure water. Generating means comprising ozone generating device for generating ozone, hydrogen peroxide adding device for adding hydrogen peroxide, and drug adding device for adding the additive substance ,
A quantitative means for quantifying the hydroxyl radical concentration by measuring the light absorption characteristics at one or more wavelengths of the hydroxyl radical-containing water produced by the production means;
Based on the quantification result of the hydroxyl radical concentration by the quantification means, a concentration adjustment means for adjusting the hydroxyl radical concentration of hydroxyl radical-containing water produced by the production means,
An ozone concentration meter to measure the initial ozone concentration before adding hydrogen peroxide,
A drug concentration meter for measuring an additive substance concentration after adding the additive substance;
A hydroxyl radical-containing water supply device comprising an ozone concentration meter that measures the final ozone concentration after adding hydrogen peroxide,
The control in the concentration adjusting means, when the quantitative result of the hydroxyl radical concentration by the quantitative means is not within the set value range,
When the initial ozone concentration by the ozone concentration meter is not within a set range, control is performed to adjust the amount of ozone generated by the ozone generator,
When the initial ozone concentration is within the set range, if the additive substance concentration by the drug concentration meter is not within the set range, control is performed to adjust the addition amount of the additive substance by the drug addition device,
Control that adjusts the amount of hydrogen peroxide added by the hydrogen peroxide addition device by comparing the final ozone concentration by the ozone concentration meter with a set value when the concentration of the additive substance by the chemical concentration meter is within a set range Hydroxyl radical-containing water supply apparatus comprising:

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