JP2009162609A - Surface contamination degree evaluation method and surface contamination degree evaluation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface contamination degree evaluation method and a surface contamination degree evaluation device capable of evaluating a surface contamination degree even in a case where surface texture of analytes changes due to the nature of adsorbed contaminant. <P>SOLUTION: The surface contamination degree evaluation method evaluates a contamination degree of a surface 1a of an analyte 1 due to adsorption of contaminant in air for the analyte required to maintain a predetermined cleanliness degree, in which the adsorbed moisture amount at the surface 1a due to adsorption of water vapor in air is measured and the contamination degree at the surface 1a is evaluated based on the difference from the adsorbed moisture amount adsorbed at the surface 1a of a reference analyte 1. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention is for evaluating the degree of contamination of the surface of an object due to adsorption of contaminants in the air on an object such as a semiconductor wafer or a glass substrate that is required to maintain a predetermined cleanliness. The present invention relates to a surface contamination degree evaluation method and a surface contamination degree evaluation apparatus.

  Conventionally, when manufacturing semiconductor devices and liquid crystal displays, chemical substances (contaminants) in the air of clean rooms and storages are adsorbed on the surface of semiconductor wafers and glass substrates (substrates, specimens), and leakage current It is known to adversely affect electrical characteristics such as an increase and a decrease in dielectric strength. For this reason, in the manufacturing process of semiconductor elements, liquid crystal displays, etc., the degree of contamination of the substrate surface is evaluated in order to prevent a decrease in yield and a decrease in product reliability due to product defects.

  Then, when evaluating the degree of contamination of the substrate surface, a temperature programmed desorption gas analysis method (TDS), a surface cleaning method, a wiping method, or the like is used.

  Thermal desorption gas analysis is a method in which a substrate is housed in a sealed container and the temperature is increased to desorb contaminants adsorbed on the substrate surface, and the contaminants in the desorbed gas are analyzed by gas chromatography (GC) or mass spectrometry. In this method, the contamination level of the substrate surface is evaluated by identification and quantification using an apparatus (mass spectrum apparatus (MS)) (see, for example, Patent Document 1).

  In the surface cleaning method, the substrate surface is cleaned with an organic solvent or pure water, and contaminants in the cleaning solution are identified and quantified by GC, MS, or ion chromatograph (IC) to evaluate the contamination level of the substrate surface. It is.

  In the wiping method, the substrate surface is wiped with a nonwoven fabric or quartz wool, and then the contaminants are eluted from the nonwoven fabric or quartz wool with an organic solvent. In this way, the contamination level of the substrate surface is evaluated.

  Thus, all of these pollution degree evaluation methods require expensive analyzers such as GC and MS. In addition, as other pollution degree evaluation methods, an optical method using a Fourier transform infrared spectrometer (FT-IR) and a method using secondary ion mass spectrometry (SIMS) are being developed. However, expensive equipment is still necessary.

On the other hand, there is a method for evaluating the degree of contamination of the substrate surface by dropping a droplet of pure water or the like on the substrate surface and measuring the contact angle of the droplet (see, for example, Patent Document 2). This contamination degree evaluation method enlarges a droplet using a magnifying glass or the like, and measures the contact angle of the droplet that changes as the amount of adsorption of the contaminant on the substrate surface increases from the enlarged image of the droplet, This is a method for evaluating the degree of contamination of the substrate surface. Therefore, it is possible to easily evaluate the degree of contamination of the substrate surface without using an expensive device such as GC or MS.
JP 2006-337031 A JP-A-8-338822

  However, in the method for measuring the contact angle of the above-mentioned droplet, for example, the nature of the contaminant adsorbed on the surface, that is, whether the contaminant is hydrophilic or hydrophobic, and further, the hydrophilic contaminant and the hydrophobic contaminant The contact angle changes depending on the ratio of For this reason, there is a problem that it is difficult to accurately evaluate the degree of contamination of the substrate surface.

  In view of the above circumstances, the present invention provides a surface contamination degree evaluation method and a surface contamination degree evaluation apparatus capable of evaluating the degree of surface contamination even when the surface property of the subject changes depending on the nature of the adsorbed contaminants. The purpose is to provide.

  In order to achieve the above object, the present invention provides the following means.

  The surface contamination degree evaluation method of the present invention is a surface contamination degree for evaluating the degree of contamination of the surface of the subject due to adsorption of contaminants in the air to the subject that is required to maintain a predetermined cleanliness. An evaluation method is characterized in that the amount of moisture adsorbed on the surface due to adsorption of water vapor in the air is measured, and the degree of contamination of the surface is evaluated based on the amount of adsorbed moisture.

  In this invention, when contaminants are adsorbed on the surface of the subject, the physicochemical properties (surface properties) of the surface change, and the amount of moisture adsorbed on the surface changes according to the amount of contaminant adsorbed. It is possible to evaluate the degree of surface contamination by measuring the amount of adsorbed water. That is, the amount of moisture adsorbed on a clean surface increases when hydrophilic contaminants are adsorbed, and the amount of adsorbed moisture decreases when hydrophobic contaminants are adsorbed. To do. For this reason, even when the surface properties change due to contaminants adsorbed on the surface of the subject, the amount of moisture adsorbed on the surface is measured, and the progress of contamination based on the amount of change (increase / decrease) in the amount of adsorbed moisture Thus, it becomes possible to evaluate the degree of surface contamination relatively accurately with respect to the conventional method for measuring the contact angle of a droplet.

  Further, in the surface contamination degree evaluation method of the present invention, the amount of moisture adsorbed on the surface is measured with the humidity of the air constant, and based on the difference from the amount of adsorbed moisture adsorbed on the surface of the reference specimen It is desirable to evaluate the degree of contamination on the surface of the subject.

  In this invention, with the humidity of the air constant, the amount of adsorbed moisture adsorbed on the surface of the subject is measured according to the humidity, and the amount of adsorbed moisture of the reference subject and the degree of contamination are evaluated. By confirming the difference (change amount) from the amount of adsorbed moisture of the object, it is possible to reliably grasp the progress of contamination and evaluate the degree of surface contamination.

  Further, in the surface contamination degree evaluation method of the present invention, the humidity of the air is changed, the amount of adsorbed moisture on the surface is measured under a plurality of humidity conditions, and the amount of change in the amount of adsorbed moisture relative to the amount of change in humidity is calculated. More preferably, the ratio is obtained, and the degree of contamination of the surface of the subject is evaluated based on the difference between the amount of change in the amount of adsorbed moisture relative to the amount of change in the humidity of the reference subject.

  In the present invention, the amount of moisture adsorbed on the surface is measured under a plurality of humidity conditions, the ratio of the amount of change in the amount of adsorbed moisture to the amount of change in the humidity of the reference sample, and the ratio of the sample for which the degree of contamination is evaluated. By confirming the difference (amount of change), the degree of contamination of the surface can be evaluated more accurately by capturing the progress of contamination.

  That is, when the surface is clean or when the amount of contaminants adsorbed on the surface is small, the amount of adsorbed moisture adsorbed on the surface changes when the humidity is changed. At this time, there is a monotonically increasing relationship in which the amount of adsorbed water increases as the humidity increases, and by measuring the amount of adsorbed water under different humidity conditions, the ratio of the amount of change in adsorbed water to the amount of change in humidity can be obtained. Since the rate of change in the amount of adsorbed moisture with respect to humidity changes due to the progress of contamination, it is possible to evaluate the degree of surface contamination based on the progress of contamination by checking this rate. In addition, when the amount of adsorbed moisture is measured under a plurality of humidity conditions and the degree of contamination is evaluated based on the rate of change in the amount of adsorbed moisture, the amount of adsorbed moisture is measured under one humidity condition. Compared with the case where the degree of contamination is evaluated based on the amount of change in the amount of adsorbed water under one humidity condition, the degree of contamination of the surface can be more accurately evaluated.

  Further, in the surface contamination degree evaluation method of the present invention, the humidity of the air is changed, and the amount of moisture adsorbed on the surface is measured under a plurality of humidity conditions to obtain the relationship between the humidity and the amount of adsorbed moisture. It is further desirable to evaluate the degree of contamination of the surface of the subject by capturing a change from the reference subject having a linear relationship.

  In this invention, the amount of moisture adsorbed on the surface is measured under a plurality of humidity conditions, and it is confirmed that the linear relationship between the humidity of the reference specimen and the amount of adsorbed moisture is broken, so that the progress of contamination can be captured. It becomes possible to evaluate the degree of contamination of the surface.

  That is, as the amount of contaminant adsorbed on the surface increases (as the contamination progresses), the linear relationship (linearity) between the humidity and the amount of adsorbed moisture breaks down, and the relationship between the humidity and the amount of adsorbed moisture becomes a curve. Change into a relationship. For this reason, by grasping the change from this linearity (by grasping that the linear relationship is no longer established), and further confirming the amount of change in the amount of adsorbed moisture relative to the amount of adsorbed moisture having a linear relationship. It is possible to reliably grasp the progress of contamination and evaluate the degree of contamination on the surface of the subject.

  Furthermore, in the surface contamination degree evaluation method of the present invention, it is desirable to measure the amount of adsorbed moisture using an infrared moisture meter.

  In this invention, it is possible to evaluate the degree of surface contamination using an infrared moisture meter that is relatively inexpensive and easy to handle, rather than an expensive device such as a gas chromatograph (GC) or mass spectrometer (MS). Become.

Moreover, when using an infrared moisture meter in this way, the amount of adsorbed moisture can be measured at a specific absorption wavelength of, for example, 1.92 to 1.95 μm, which is absorbed by moisture. The specific absorption wavelength is determined by, for example, hydroxyl groups (OH) of organic compounds (pollutants) such as alcohols and hydroxycarboxylic acids present in the air of clean rooms and storages when manufacturing semiconductor devices and liquid crystal displays. , Close to the specific absorption wavelength of the amino group (NH ₂ ). For this reason, when the amount of moisture adsorbed on the surface of the subject is measured, it can be measured as an apparent amount of adsorbed moisture obtained by combining the actual amount of adsorbed moisture with the hydroxyl group or amino group of the contaminant adsorbed on the surface. As a result, a measurement result including information on the adsorbed contaminants can be obtained as compared with the case where only the adsorbed moisture amount is detected, so that the contamination state can be evaluated in more detail based on the apparent adsorbed moisture amount.

  The surface contamination degree evaluation apparatus of the present invention is a surface for evaluating the degree of contamination of the surface of the subject due to adsorption of contaminants in the air to the subject that is required to maintain a predetermined cleanliness. A contamination degree evaluation apparatus, a container for storing the subject, a humidity adjusting means for adjusting the humidity in the container, a moisture meter for measuring the amount of adsorbed moisture on the surface of the subject stored in the container, It is characterized by comprising.

  In the present invention, it is possible to obtain the same effect as the above-described surface contamination degree evaluation method of the present invention.

  According to the surface contamination degree evaluation method and the surface contamination degree evaluation apparatus of the present invention, when the surface property is changed by the contaminant adsorbed on the surface of the subject, compared to the conventional method of measuring the contact angle of the droplet. However, by measuring the amount of adsorbed moisture adsorbed on the surface according to the change in surface properties and capturing the amount of change (increase / decrease) in the amount of adsorbed moisture, it becomes possible to check the progress of contamination. It becomes possible to evaluate the degree of contamination.

  In addition, by measuring the amount of moisture adsorbed on the surface in this way and evaluating the degree of surface contamination, it is not necessary to use an expensive device such as a gas chromatograph (GC) or a mass spectrometer (MS), and the surface It becomes possible to evaluate the degree of contamination.

  Hereinafter, a surface contamination degree evaluation method and a surface contamination degree evaluation apparatus according to a first embodiment of the present invention will be described with reference to FIGS. In the present embodiment, the description will be made on the assumption that the degree of contamination of the surface of a semiconductor wafer or a glass substrate of a liquid crystal display (subject) required to maintain a predetermined cleanliness is evaluated.

  As shown in FIG. 1, the surface contamination degree evaluation apparatus A according to the present embodiment measures the humidity in the container 2 by arranging a container 2 that houses a substrate (subject) 1 and a humidity sensor 3 a in the container 2. A humidity meter 3 that adjusts the humidity (relative humidity) in the container 2, and an infrared moisture meter (moisture meter) that measures the amount of moisture adsorbed on the surface 1 a of the substrate 1 accommodated in the container 2. ) 5 and a processing device 6 such as a personal computer for recording and processing the measured values of the hygrometer 3 and the infrared moisture meter 5.

  Humidity adjusting means 4 is connected to the container 2, an air supply port 2 a for taking in the humidity adjusting air sent from the humidity adjusting means 4, and an exhaust port 2 b for discharging the internal air to the outside It is formed with. In addition, a reflecting plate 2c on which the substrate 1 accommodated in the container 2 is placed with its surface 1a facing upward is provided inside.

  The humidity adjusting means 4 includes a dry air manufacturing device 4a and a humidity adjusting device 4b, and feeds the dry air manufactured by the dry air manufacturing device 4a to the humidity adjusting device 4b. The humidity adjusting device 4b adjusts the humidity to a desired humidity. The adjusted humidity adjustment air is configured to be supplied into the container 2 from the air supply port 2a.

  The infrared moisture meter 5 is provided so that an optical fiber cable 5a extends from the outside into the container 2 and irradiates the surface 1a of the substrate 1 with infrared rays from the tip of the optical fiber cable 5a. The infrared moisture meter 5 has a water absorption wavelength light having a wavelength of 1.92 to 1.95 μm, which is easily absorbed by water, a wavelength of 1.80 μm and a wavelength of 2.10 μm, which are not easily affected by moisture, for example. The reference wavelength light is alternately irradiated onto the surface 1a of the substrate 1, and the reflected light is received, and the moisture meter output value (IM-D value (mV)) corresponding to the moisture content is given to the processing device 6. Output. Then, the amount of moisture adsorbed on the surface 1a of the substrate 1 is calculated from the IM-D value by the processing device 6. Incidentally, the reference wavelength light is irradiated to perform stable measurement excluding the influence of the color tone of the surface 1a of the substrate 1 and the like.

  Next, a method for evaluating the contamination degree of the surface 1a of the substrate 1 using the surface contamination degree evaluation apparatus A having the above configuration will be described, and the surface contamination degree evaluation method and the surface contamination degree evaluation apparatus A according to the present embodiment will be described. The effects will be described.

  In the present embodiment, the humidity of the internal air (air) of the container 2 of the surface contamination degree evaluation apparatus A is kept constant by the humidity adjusting means 4. Thus, water vapor in the internal air is adsorbed on the surface 1a of the substrate 1 installed on the reflector 2c according to the constant humidity condition, and the amount of adsorbed moisture adsorbed on the surface 1a of the substrate 1 is determined as the infrared moisture meter 5. Measure by.

  At this time, when a contaminant is adsorbed on the surface 1a of the substrate 1 with respect to the amount of adsorbed moisture adsorbed on the surface 1a of the clean substrate (reference object) 1, it depends on the amount of adsorbed contaminant. Even when the surface properties change and the humidity is kept constant, the amount of adsorbed moisture adsorbed on the surface 1a of the substrate 1 increases or decreases.

  That is, when hydrophilic contaminants are adsorbed and the surface properties become hydrophilic, as shown in FIG. 2, the adsorbed amount of adsorbed water adsorbs on the clean surface (clean surface) 1a. When the amount of water increases and the hydrophobic contaminants adsorb and the surface properties become hydrophobic, the amount of adsorbed water is less than the amount of adsorbed water adsorbed on the clean surface 1a as shown in FIG. Decrease. Further, such an increase / decrease amount (change amount) of the amount of adsorbed water changes according to the amount of adsorbed contaminants adsorbed on the surface 1 a of the substrate 1.

  Therefore, with the humidity kept constant, the amount of moisture adsorbed on the substrate surface 1a is measured according to the humidity, and the amount of adsorbed moisture adsorbed on the surface 1a of the clean substrate and the degree of contamination are evaluated. By confirming the difference (change amount) from the amount of adsorbed moisture adsorbed on the surface 1a of the substrate 1 to be performed, it becomes possible to evaluate the degree of contamination of the surface 1a.

  Moreover, when manufacturing a semiconductor element or a liquid crystal display, a semiconductor wafer or a liquid crystal glass substrate (substrate 1) reaches a finished product through many manufacturing processes. And the chemical substance etc. (contaminant) in the air of the clean room which performs each manufacturing process, and the storage (stocker) which temporarily stores the board | substrate 1 adsorb | suck to the surface 1a of the board | substrate 1, and the surface 1a of the board | substrate 1 becomes Contaminated.

 Therefore, the amount of adsorbed moisture adsorbed on the surface 1a of the substrate 1 in a clean state is measured, and the adsorbed moisture adsorbed on the surface of the same substrate 1 after the manufacturing process (for example, after each manufacturing process is completed). The amount is measured and the difference (change amount) between the amount of adsorbed moisture on the substrate surface 1a in a clean state and the amount of adsorbed moisture on the substrate surface 1a after the manufacturing process, or the substrate (reference object) surface 1a in the previous process By confirming the difference (change amount) between the amount of adsorbed moisture and the amount of adsorbed moisture on the substrate (subject) surface 1a in the subsequent process, the progress of contamination can be confirmed.

  Therefore, in the surface contamination degree evaluation method and the surface contamination degree evaluation apparatus A of the present embodiment, even when the surface property changes due to the contaminant adsorbed on the surface 1a of the substrate 1, the humidity of the air is kept constant. Measure the amount of moisture adsorbed on the surface 1a of the substrate 1 according to the humidity, and confirm the difference between the amount of moisture adsorbed on the reference substrate 1 and the amount of moisture adsorbed on the substrate 1 for evaluating the degree of contamination. (Based on the change in the amount of adsorbed water) to reliably grasp the progress of contamination and to evaluate the contamination degree of the surface 1a relatively accurately with respect to the conventional method of measuring the contact angle of a droplet. It becomes possible.

  Furthermore, since it becomes possible to evaluate the contamination degree of the surface 1a using the infrared moisture meter 5 which is relatively inexpensive and easy to handle, an expensive apparatus such as a gas chromatograph (GC) or a mass spectrometer (MS) can be used. There is no need to use it, and the contamination degree of the surface 1a can be easily evaluated.

Here, when the infrared moisture meter 5 is used in this way, the amount of adsorbed moisture can be measured at a specific absorption wavelength of, for example, 1.92 to 1.95 μm absorbed by moisture. And when this specific absorption wavelength manufactures a semiconductor element, a liquid crystal display, etc., hydroxyl groups (OH) of organic compounds (pollutants) such as alcohols and hydroxycarboxylic acids present in the air of a clean room or a storage room, close to the specific absorption wavelength of the amino group (NH _2). Therefore, when the amount of moisture adsorbed on the surface 1a of the substrate 1 is measured, FIG. 4 (when hydrophilic contaminants are adsorbed on the surface 1a) and FIG. 5 (hydrophobic contaminants adsorb on the surface 1a). As shown in the case), it can be measured as an apparent amount of adsorbed moisture obtained by combining the actual amount of adsorbed moisture with the hydroxyl group or amino group of the contaminant adsorbed on the surface 1a. As a result, a measurement result including information on the adsorbed contaminants can be obtained as compared with the case where only the amount of adsorbed moisture is detected. And when the type and concentration of contaminants in the air are known, such as in clean rooms and storages for manufacturing semiconductor elements and liquid crystal displays, the amount of adsorbed moisture and contaminants adsorbed on the surface 1a under constant humidity conditions By preliminarily obtaining the relationship between the adsorbed amounts, it becomes possible to evaluate the contamination state in more detail from the apparent adsorbed water amount.

  Next, a surface contamination degree evaluation method according to the second embodiment of the present invention will be described with reference to FIGS. In the present embodiment, similarly to the first embodiment, the surface contamination degree evaluation apparatus A is used to measure the surface of a substrate (subject) of a semiconductor wafer or a glass substrate of a liquid crystal display that is required to maintain a predetermined cleanliness. The description will be made on the assumption that the degree of contamination is evaluated.

  Here, as in the first embodiment, the difference between the adsorbed moisture amount of the reference substrate 1 measured in a state where the humidity is constant and the adsorbed moisture amount of the substrate 1 on which the contamination degree is evaluated is confirmed to be the surface. When evaluating the contamination level of 1a, the entire measured value (IM-D value, amount of adsorbed water) is shifted up and down due to changes in the installation state of the substrate and, for example, the voltage of the infrared moisture meter, An error may occur due to characteristics such as the baseline changing with time.

  On the other hand, in the surface contamination degree evaluation method of the present embodiment, the humidity of the internal air (air) of the container 2 of the surface contamination degree evaluation apparatus A is changed by the humidity adjusting means 4, and the surface of the substrate 1 under a plurality of humidity conditions. The amount of moisture adsorbed on 1a is measured.

  When the surface 1a is in a clean state or when the amount of adsorbed contaminants adsorbed on the surface 1a is small, the amount of adsorbed moisture adsorbed on the surface 1a changes when the humidity is changed. And the amount of adsorbed water can be obtained by linear regression. That is, when the surface 1a is in a clean state or when the amount of contaminants adsorbed is small, the relationship between the humidity and the amount of adsorbed water is a linear relationship.

  Then, when hydrophilic contaminants are adsorbed and the surface properties become hydrophilic, as shown in FIG. 6, the amount of change in the humidity of the substrate (reference specimen) 1 having a clean surface 1a. The ratio of the amount of change in the amount of adsorbed water to the surface, that is, the slope of the linear relationship between the humidity of the substrate 1 and the amount of adsorbed water with the clean surface 1a, and the amount of adsorbed moisture and the amount of adsorbed water The slope of the relationship increases.

  In addition, when hydrophobic contaminants are adsorbed and the surface properties become hydrophobic, as shown in FIG. 7, the linear relationship between the humidity of the substrate 1 with the clean surface 1a and the amount of adsorbed water is obtained. The inclination of the relationship between the humidity of the substrate 1 to which the contaminant is adsorbed and the amount of adsorbed water becomes smaller.

  For this reason, the degree of contamination of the surface 1a is evaluated by grasping the progress of contamination by checking the amount of change (slope) of the amount of change in the amount of adsorbed moisture relative to the amount of change in humidity that changes with the progress of contamination. It becomes possible to do. In addition, by measuring the amount of adsorbed moisture under a plurality of humidity conditions and evaluating the degree of contamination based on the amount of change in slope, the amount of adsorbed moisture is measured under one humidity condition. An error that occurs when the degree of contamination is evaluated based on the amount of change in the amount of adsorbed moisture can be suppressed, and the degree of contamination of the surface 1a can be more accurately evaluated. In addition, it is possible to check the progress of contamination by checking the amount of change in inclination over time. In the present embodiment, since the change amount of the tilt is confirmed, the evaluation can be performed by performing the measurement under at least two humidity conditions.

  Next, a surface contamination degree evaluation method according to a third embodiment of the present invention will be described with reference to FIG.

  In the present embodiment, as in the second embodiment, the humidity of the internal air of the container 2 of the surface contamination degree evaluation apparatus A is changed by the humidity adjusting means 4 and is adsorbed on the surface 1a of the substrate 1 under a plurality of humidity conditions. Measure moisture content.

  Then, the relationship between the humidity and the amount of adsorbed moisture is obtained. At this time, if the humidity condition to be measured is not two conditions but three conditions or more as in the second embodiment, whether or not the change in the amount of adsorbed moisture with respect to the humidity change is highly linear, and the linearity The deviation from can be grasped.

  For example, as shown in FIG. 8, the relationship between the humidity and the amount of adsorbed moisture (linearity or deviation from linearity) changes with the progress of contamination of the surface 1a.

  Therefore, in the surface contamination degree evaluation method of the present embodiment, by capturing that the relationship between the humidity and the amount of adsorbed water changes from linearity (by capturing that the proportional relationship is no longer established), a straight line is further obtained. By confirming the amount of change in the amount of adsorbed water relative to the amount of adsorbed water having a general relationship, it becomes possible to grasp the progress of contamination and evaluate the degree of contamination of the surface 1a of the substrate 1. Also, by capturing the amount of change from linearity over time, it is possible to reliably check the progress of contamination. In the present embodiment, since it is a method of capturing a change from a linear relationship, it is desirable to measure under three or more humidity conditions.

  The first, second, and third embodiments of the surface contamination degree evaluation method and the surface contamination degree evaluation device according to the present invention have been described above, but the present invention is not limited to the above embodiments, and the gist thereof As long as it does not deviate from the above, it can be appropriately changed. For example, in the first to third embodiments, the moisture meter of the surface contamination degree evaluation apparatus A is the infrared moisture meter 5, and the infrared moisture meter 5 measures the amount of moisture adsorbed on the surface 1a. However, the moisture meter according to the present invention need not be limited to the infrared moisture meter 5 as long as the amount of adsorbed moisture can be measured.

  In the first to third embodiments, the subject according to the present invention has been described as being the substrate 1 such as a semiconductor wafer or a glass substrate. However, the present invention is applicable to the evaluation of the contamination level of the substrate surface 1a. The present invention is not limited to the application, and can be applied to all subjects that are required to maintain a predetermined cleanliness.

  Further, in the first to third embodiments, the substrate (subject) 1 is accommodated in the container 2 of the surface contamination degree evaluation apparatus A, and the contamination degree of the substrate surface 1a is evaluated. Since the space for manufacturing the element and the liquid crystal display (in the clean room or in the manufacturing apparatus) is controlled in both temperature and humidity, there is no need to put the subject in the container 2 if the humidity environment is stable. It is possible to evaluate in an open state.

  Examples of the present invention will be specifically described below. However, the present invention is not limited to this example.

  In this embodiment, the contamination level evaluation apparatus A shown in FIG. 1 is used to actually measure the amount of adsorbed moisture on the surface 1a of the substrate 1 of each of the liquid crystal glass substrate and the semiconductor wafer, and evaluate the contamination level of the substrate surface 1a. It is what I did.

First, evaluation of the liquid crystal glass substrate 1 will be described.
In the present embodiment, a liquid crystal glass substrate 1 formed with a thickness of 0.7 mm is used, and a reflective infrared moisture meter 5 (manufactured by Fuji Work Co., Ltd.) is used for measuring the amount of adsorbed moisture on the surface 1a of the liquid crystal glass substrate 1. IM-3SCV MODEL-1900) was used. In addition, the liquid crystal glass substrate surface 1a is cleaned by alternately washing with ethyl alcohol and hexane, and the clean liquid crystal glass substrate 1 is accommodated in a container 2 having a capacity of about 2.3 liters for testing. went. Further, the temperature in the container 2 is always kept at 20 to 21 ° C., and in the stage before the start of the test, dry air having a humidity (relative humidity) of 0.4 to 0.5% is supplied at a flow rate of 1.0 SLM. The air environment in the container 2 was dried.

  In this embodiment, after the liquid crystal glass substrate 1 is accommodated in the container 2, the humidity operation is performed after 1 day, 3 days, 4 days, 7 days, and 9 days, and the humidity is reduced from about 0.5%. The change of the output value (IM-D value (mV)) of the infrared moisture meter 5 was measured by changing the level to about 80%. At this time, the dry air produced by the dry air production device 4a is mixed with the high-humidity air produced by introducing a part of the dry air into the pure water impinger of the humidity adjustment device 4b. ) Was supplied into the container 2 at a flow rate of 1.0 SLM, and the humidity was continuously changed from about 0.5% to about 80%.

  FIG. 9 shows test results obtained under the above-described conditions, and shows IM-D values with respect to humidity. From this result, in the liquid crystal glass substrate 1, it was confirmed that IM-D value rose with the elapsed days after washing | cleaning in all humidity conditions. That is, in any humidity measurement, it is recognized that the IM-D value rises according to the number of days elapsed, and the contaminant contained in the internal air on the surface 1a of the liquid crystal glass substrate 1 in the container 2 It was confirmed that the contamination progressed over time and continuously.

  Next, FIG. 10 shows a change amount (ΔIM-D value) of the IM-D value with respect to humidity. From this result, it was confirmed that the amount of change in the IM-D value decreased with the passage of days after washing. In particular, after 7 days, the change in the amount of adsorbed moisture with respect to the increase in humidity is small, and hydrophobic contaminants are adsorbed on the surface 1a of the liquid crystal glass substrate 1, and the influence of this hydrophobic contaminant is strong.

  As a result, in this example, the surface 1a of the liquid crystal glass substrate 1 starts to progress contamination between 1 day and 3 days later, and the contamination gradually proceeds as the number of days elapses. It can be confirmed by measuring the value, that is, the amount of adsorbed water. Then, as the number of days elapses, the amount of change in the IM-D value decreases, and the linearity is further lost. Therefore, hydrophobic contaminants are adsorbed on the liquid crystal glass substrate 1, and the surface properties gradually become hydrophobic. It can be confirmed that it changes to enhance sex.

  Therefore, the amount of adsorbed moisture on the surface 1a of the liquid crystal glass substrate 1 can be measured using the infrared moisture meter 5, and the amount of adsorbed moisture is measured in this way to confirm the amount of change and the collapse of linearity. It has been proved that the progress of contamination can be grasped and the surface contamination degree of the liquid crystal glass substrate 1 can be evaluated.

  Here, at the stage where the measurement was completed after 9 days, the liquid crystal glass substrate 1 was taken out of the container 2 and exposed and left for 9 days in the room. The liquid crystal glass substrate 1 was returned to the container 2 supplied with dry air after 9 days of exposure (18 days later), and remeasured 3 days later (21 days later).

  As a result, as shown in FIG. 11, it was confirmed that the response of the change amount of the IM-D value with respect to humidity was recovered by exposure to room air. However, in the relationship between the humidity and the amount of change in the IM-D value, a curved relationship similar to that after 3 days in FIG. 10 was maintained. The recovery of the responsiveness of the change amount of the IM-D value with respect to the humidity suggests that the hydrophobicity of the surface 1a of the liquid crystal glass substrate 1 has been recovered. On the other hand, maintaining the change from the linear relationship (maintaining the curved relationship) suggests that contaminants remain on the surface 1 a of the liquid crystal glass substrate 1. Thus, by examining the relationship between the humidity and the IM-D value in detail, it is also possible to grasp the presence of surface contamination that cannot be detected simply by changing the amount of change in the IM-D value with respect to the humidity.

Next, evaluation of the semiconductor wafer 1 will be described.
In this example, a CZp type semiconductor wafer 1 having an orientation of 100 and a thickness of 625 ± 25 μm was used. The humidity operation was performed after 2 days, 6 days, and 8 days, and other conditions were tested in the same manner as the evaluation of the liquid crystal glass substrate 1.

  FIG. 12 shows the IM-D value with respect to humidity (relative humidity). From this result, in the semiconductor wafer 1, it was confirmed that the IM-D value increased with the elapsed days after cleaning in all humidity conditions. That is, it is recognized that the IM-D value rises according to the number of days elapsed even when measured at any humidity, and the contamination of the surface 1a of the semiconductor wafer 1 in the container 2 continues with time. Confirmed to proceed. Moreover, the response of IM-D value fell in the low humidity region after 6 days and 8 days after 2 days.

  Next, FIG. 13 shows a change amount (ΔIM-D value) of the IM-D value with respect to humidity. From this result, it was confirmed that the amount of change in the IM-D value decreased with the passage of days after washing. In particular, after 6 days, the change in the amount of adsorbed moisture with respect to the increase in humidity is small, and hydrophobic contaminants are adsorbed on the surface of the liquid crystal glass substrate, and the influence of this hydrophobic contaminant is strong. In addition, the relationship between the humidity and the amount of change in the IM-D value shows a substantially linear relationship after 2 days, whereas the linearity is broken after 6 days.

  Therefore, it was proved that the amount of adsorbed moisture was measured on the semiconductor wafer 1 and the amount of change and linearity were confirmed to catch the progress of contamination and evaluate the degree of surface contamination.

It is a figure which shows the surface contamination degree evaluation apparatus which concerns on embodiment of this invention. It is a figure which shows the difference in the amount of adsorption | suction water | moisture content of the clean surface in the state which made humidity constant, and the surface which the hydrophilic contaminant adsorb | sucked. It is a figure which shows the difference of the adsorption | suction moisture content of the surface in which the humidity was made constant and the surface which the hydrophobic contaminant adsorb | sucked. It is a figure which shows the difference of the apparent amount of adsorption | suction water | moisture contents of the surface where the humidity was made constant and the surface which the hydrophilic contaminant adsorb | sucked. It is a figure which shows the difference in the amount of apparent adsorption | suction moisture of the clean surface in the state which made humidity constant, and the surface which the hydrophobic contaminant adsorb | sucked. It is a figure which shows the difference in the inclination of the relationship between humidity and the amount of adsorption | suction moisture in the surface which the clean surface and the hydrophilic contaminant adsorb | sucked. It is a figure which shows the difference in the inclination of the relationship between humidity and the amount of adsorption | suction moisture in the surface which the clean surface and the hydrophobic contaminant adsorb | sucked. It is a figure which shows the change of the relationship between humidity and the amount of adsorption | suction water accompanying the progress of contamination. It is the figure which showed the result of the evaluation test using the liquid crystal glass substrate of an Example, and is a figure which shows the IM-D value with respect to humidity. It is the figure which showed the result of the evaluation test using the liquid crystal glass substrate of an Example, and is a figure which shows the variation | change_quantity of the IM-D value with respect to humidity. It is the figure which showed the result of the evaluation test using the liquid crystal glass substrate of an Example, and is a figure which shows the variation | change_quantity of the IM-D value with respect to the humidity 21 days after washing | cleaning. It is the figure which showed the result of the evaluation test using the semiconductor wafer of an Example, and is a figure which shows the IM-D value with respect to humidity. It is the figure which showed the result of the evaluation test using the semiconductor wafer of an Example, and is a figure which shows the variation | change_quantity of the IM-D value with respect to humidity.

Explanation of symbols

1 Subject (substrate, liquid crystal glass substrate, semiconductor wafer)
DESCRIPTION OF SYMBOLS 1a Surface 2 Container 2a Air supply port 2b Exhaust port 2c Reflector 3 Hygrometer 3a Humidity sensor 4 Humidity adjustment means 4a Dry air manufacturing apparatus 4b Humidity adjustment apparatus 5 Infrared moisture meter (moisture meter)
5a Optical fiber cable 6 Processing device A Surface contamination degree evaluation device

Claims (6)

A surface contamination degree evaluation method for evaluating the degree of contamination of the surface of the subject by adsorbing contaminants in the air for the subject required to maintain a predetermined cleanliness,
A surface contamination degree evaluation method, comprising measuring an amount of moisture adsorbed on the surface due to adsorption of water vapor in the air, and evaluating the degree of contamination of the surface based on the amount of adsorbed moisture. In the surface contamination degree evaluation method according to claim 1,
Measuring the amount of moisture adsorbed on the surface with the humidity of the air constant, and evaluating the degree of contamination of the surface of the subject based on the difference from the amount of adsorbed moisture adsorbed on the surface of the reference subject A method for evaluating surface contamination. In the surface contamination degree evaluation method according to claim 1 or 2,
Changing the humidity of the air, measuring the amount of moisture adsorbed on the surface under a plurality of humidity conditions, determining the ratio of the amount of change in the amount of adsorbed moisture to the amount of change in humidity, and changing the humidity of the reference specimen A method for evaluating the degree of contamination of a surface, wherein the degree of contamination of the surface of the subject is evaluated on the basis of the difference between the amount of change in the amount of adsorbed water and the amount of adsorption. In the surface contamination degree evaluation method according to any one of claims 1 to 3,
The humidity of the air is changed, and the amount of moisture adsorbed on the surface is measured under a plurality of humidity conditions to determine the relationship between the humidity and the amount of adsorbed moisture, and for a reference specimen in which the relationship is a linear relationship A method for evaluating the degree of contamination of a surface, characterized in that the degree of contamination on the surface of the subject is evaluated by capturing a change from the relationship. In the surface contamination degree evaluation method in any one of Claims 1-4,
A method for evaluating the degree of surface contamination, wherein the amount of adsorbed moisture is measured using an infrared moisture meter. A surface contamination degree evaluation apparatus for evaluating the degree of contamination of the surface of the subject by adsorbing contaminants in the air for the subject required to maintain a predetermined cleanliness,
A container that contains the subject, humidity adjusting means for adjusting the humidity in the container, and a moisture meter that measures the amount of moisture adsorbed on the surface of the subject contained in the container. Surface contamination degree evaluation device characterized by

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