JP2005114411A - Acquisition device of data related to wet angle of sample with respect to liquid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure the wet angle of the liquid on the surface of a minute solid with high precision. <P>SOLUTION: The acquisition device of data related to the wet angle of sample with respect to liquid is equipped with a sample chamber 2, capable of controlling atmosphere, a sample holder 14 for holding the sample 13 introducing into the sample chamber 2 and controlling the temperature of the sample introduced, a scanning electron microscope for observing the sample 13 held to the sample holder 14 and an electron gun driving means for collectively irradiating the surface of the sample with an electron beam from the electronic gun 3 of the scanning electron microscope to impart a nucleus for dewing the liquid on the surface of the sample. The sample holder 14 is equipped with a means, having a mechanism of inclination and rotation, in addition to the movement of the position of the sample or a means for altering the position of the lens barrel 1 of the scanning electron microscope and a reflected electron detector 12, to make the lens barrel 1 and the reflected electron detector 12 face the surface of the sample. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an apparatus for measuring characteristics of a solid surface in the field of medicine and the like, and more particularly, to an apparatus for acquiring information relating to a wetting angle of a solid material with respect to a liquid.

  In general, the water repellency and oil repellency of a sample are evaluated by the contact angle of a droplet on the sample surface. This contact angle refers to the angle on the side containing the liquid among the angles formed by the tangent line drawn to the liquid and the solid surface at the contact point of the solid, liquid, and gas phases. Conventionally, such contact angle is measured by observing a droplet from the side using an optical microscope with a goniometer. However, in this method, it is difficult to determine the contact point of the three phases of liquid, gas, and solid, and there is a limit to the size of the sample to be measured. Therefore, a method for observing the droplet from above has been proposed (Patent Document 1 and Patent Document 2 below). In these methods, a droplet having a known volume or mass is attached to a sample, the diameter of the droplet is measured from above, and the contact angle is calculated from two of the volume or mass and the measured diameter.

  In addition, the droplet diameter is measured by observing the droplet from above, and the height of the droplet is measured using a non-contact distance measuring means such as an ultrasonic distance measuring means, and the contact angle is calculated from the height and diameter. There has also been proposed a method for calculating (Patent Document 3 below).

  There has also been proposed a method of photographing a droplet from a predetermined angle with a CCD camera and calculating a contact angle from the image and the photographing angle (Patent Document 4 below).

  In addition, for the purpose of eliminating the influence of evaporation, etc., and uniformly depositing droplets of uniform volume or mass on the sample, droplets are generated by condensation, and the height and diameter thereof are measured with an optical microscope or laser. There has also been proposed a method of obtaining a contact angle by measuring with a non-contact distance measuring means such as a microscope, a radar system, an infrared system, or an ultrasonic system (Patent Document 5 below).

Furthermore, as a method for measuring the wetting angle of solid particles, a method of calculating the wetting angle by floating solid particles in a medium liquid and observing with a microscope from the lateral direction has been proposed (Patent Document 6 below).
JP-A-1-126523 JP-A-5-232009 JP-A-8-59988 JP 2002-188986 A JP 2002-62242 A JP-A-8-68742

  Conventionally, the characteristics of the surface of solid particles have been measured in various fields such as chemicals, medicines, foods, printing materials, surfactants, etc. Among them, the contact angle (wetting angle) of particles to the liquid should be measured. Has become an important issue.

  As a method for measuring the wetting angle, it is desirable to directly measure the wetting angle of the droplets adhering to the particle surface, but in practice it becomes very difficult when the diameter of the particle itself is reduced. Therefore, a method of indirectly measuring the wetting angle is generally employed. For example, there is a method in which a small amount of liquid droplets are deposited on a flat plate of the same material as the measurement target particle and the contact angle is measured. However, since this method regards the contact angle on the flat plate as an approximation of the wetting angle of the particle to be measured, the obtained wetting angle includes a large error. Furthermore, when the particle surface is contaminated, or when the particle surface is chemically modified by chemical treatment, a large difference occurs in the wetting angle even if the flat plate is the same material as the particle. Therefore, in order to measure the wetting angle of particles, it is necessary to directly observe the wetting angle of droplets on the particles.

  However, in each of the above-described conventional techniques, at the stage of measuring the parameter for obtaining the wetting angle, the observation technique has a limit of spatial resolution, and therefore there is a limit on the size of the sample to be measured. For example, when an optical microscope is used, it is difficult to accurately observe a droplet on the surface of a solid particle having a diameter of a micron order or less.

  There is also a need for a mechanism that can uniformly deposit droplets of uniform volume or mass on the sample and maintain them during the measurement.

  The present invention has been made in view of the above-described conventional problems, and provides an apparatus capable of accurately measuring the wetting angle of a liquid on a minute solid surface.

  In order to solve the above-mentioned problems, the present invention provides an apparatus for acquiring information on the wetting angle of a sample with respect to a liquid, which holds and introduces a sample chamber capable of controlling the atmosphere, and a sample introduced into the sample chamber. A sample holder for controlling the temperature of the sample, a scanning electron microscope for observing the sample held by the sample holder, and an electron beam from the electron gun of the scanning electron microscope on the sample surface And an electron gun driving means for providing a nucleus for condensing the liquid on the surface of the sample.

  In particular, in the apparatus configured as described above, the scanning electron microscope includes a lens barrel including an electron gun chamber having an electron gun and a lens chamber having a plurality of lenses, and a reflected electron detector for detecting reflected electrons from the sample. And the two chambers are each adjusted to a predetermined different degree of vacuum by a separate exhaust system.

  Further, in the apparatus having the above configuration, the degree of vacuum in the sample chamber is adjusted to an arbitrary set value by controlling both a valve and an exhaust system of a gas introduction path including a liquid component. To do.

  In the apparatus having the above-described configuration, the sample temperature on the sample holder is adjusted to an arbitrary set value by controlling both the heating and cooling mechanisms from the outside.

  In the apparatus configured as described above, the sample holder has a tilting and rotating mechanism in addition to the movement of the sample position.

  The apparatus having the above-described configuration further includes means for changing the positions of the column and the backscattered electron detector of the scanning electron microscope so that the tube and the backscattered electron detector are opposed to the sample surface. It is characterized by that.

  Further, according to the method for obtaining information on the wetting angle of the sample with respect to the liquid according to the present invention, the sample is held in a sample chamber where the atmosphere can be controlled, and an electron beam is concentrated on the sample surface from an electron gun of a scanning electron microscope. The sample is irradiated with a nucleus for condensing liquid on the sample surface, a droplet is grown on the sample surface, and the sample is observed with a scanning electron microscope.

  In particular, in the method having the above-described configuration, the sample is observed with a scanning electron microscope from any direction by tilting and rotating the sample holder.

  In the method of the above configuration, the observation of the sample with a scanning electron microscope is performed by making the barrel of the scanning electron microscope and the backscattered electron detector movable and facing the sample from an arbitrary direction. Features.

(Function)
According to the above configuration, the present invention makes it possible to observe droplets attached to the surface of a sample having a minute size using an electron beam. In addition, it is possible to uniformly deposit a droplet having a uniform volume or mass on the sample and maintain it during the measurement. Furthermore, the angle at which the sample of the lens barrel of the scanning electron microscope faces the sample can be freely set, and the droplets adhering to the sample surface can be observed from an arbitrary angle.

  According to the present invention, it is possible to accurately measure the wetting angle of a liquid on the surface of a minute solid. Therefore, it goes without saying that not only toner particles but also electrophoretic particles and general powders and fine particles used in electrophoretic display devices can measure the wetting angle with an arbitrary liquid. In addition, by applying nuclei, it is possible to measure the difference and distribution of the wetting angle in local fine parts on the surface of various devices and relatively large specimens, and to evaluate the uniformity of the surface state. It was.

  Next, embodiments of the present invention will be described in detail with reference to the drawings.

(First embodiment)
FIG. 1 is a block diagram showing a first embodiment of the present invention.

  In the figure, reference numeral 1 denotes an electron optical column which is a column of a scanning electron microscope, and 2 denotes a sample chamber (sample chamber) for observing a sample.

  Inside the electron optical column 1, there are provided an electron gun chamber 4 in which an electron gun 3 is installed, a lens chamber 9 having a condenser lens 5, a scanning coil 6, an astigmatism correction device 7, and an objective lens 8. .

  In addition, a sample holder 14 holding a sample 13 is introduced into the sample chamber 2 through a preliminary exhaust chamber 15 that has been exhausted to a predetermined degree of vacuum in advance.

  The electron gun chamber 4 in the electron optical column 1 is connected from the exhaust unit 16 to an exhaust system (not shown), and the lens chamber 9 is connected from the exhaust unit 17 to an exhaust system (not shown). It is possible to maintain the chamber vacuum. On the other hand, the sample chamber 2 is connected to an exhaust system (not shown) from the exhaust unit 18, and a gas introduction unit 20 is provided via a valve. By controlling the exhaust system and the valve from the outside, any gas can be obtained. It is possible to maintain an arbitrary degree of vacuum in an atmosphere (for example, water or an organic solvent).

  Reference numerals 10 and 11 denote orifices that partition regions having different pressures and allow an electron beam to pass therethrough. The orifice 10 partitions the electron gun chamber 4 and the lens chamber 9, and the orifice 11 partitions the lens chamber 9 and the sample chamber 2. Usually, an objective aperture is used as the orifice 11.

  Furthermore, a backscattered electron detector 12 for detecting backscattered electrons generated from the sample is installed on the surface of the orifice 11 facing the sample.

Next, a method for measuring the wetting angle of the sample surface will be described. First, the degree of vacuum in each of the electron gun chamber 4, the sample chamber 2, and the lens chamber 9 is adjusted. Since the electron gun chamber 4 needs to generate an electron beam by the electron gun 3, the electron gun chamber 4 is exhausted from the exhaust unit 16 and adjusted to a vacuum degree of about 10 ⁻³ Pa.

  On the other hand, the sample chamber 2 closes the gas introduction part 20 and exhausts it from the exhaust part 18 to adjust the degree of vacuum to about 1 Pa. The lens chamber 9 located between the sample chamber 2 and the electron gun chamber 4 is also evacuated from the exhaust unit 17 and adjusted to a vacuum degree of about 1 Pa.

  Next, the sample holder 14 carrying the sample 13 is introduced into the sample chamber 2 through the preliminary exhaust chamber 15 and adjusted so that the sample 13 is positioned on the optical axis of the electron beam generated from the electron gun 3. In this embodiment, toner particles having a diameter of 1 μm are used as the sample 13.

  Next, electrons are emitted from the electron gun 3, and the condenser lens 5, the astigmatism correction device 7, and the objective lens 8 are operated to irradiate a finely focused electron beam on the toner particles. Further, the scanning coil 6 is driven to deflect the electron beam, and the electron beam is scanned on the surface of the toner particles. At this time, an image of toner particles can be obtained by displaying the signal detected by the backscattered electron detector 12 in synchronization with the signal for scanning the electron beam.

  Although it is possible to deposit liquid droplets on the sample by introducing moisture from the gas introduction unit 20 to cause condensation, if it is desired to measure the wetting angle at a specific position on the surface of the sample, it is ensured at the target position. In order to cause condensation, it is desirable to impart condensation nuclei to the sample surface. In the present invention, as a method for imparting the nucleus, the use of an electron beam of a scanning electron microscope is considered, and the method will be described below.

  The first method is a method in which the acceleration voltage of the electron gun 3 is set high, the target portion of the surface of the sample 13 is irradiated intensively without scanning, and the sample surface is shaved to form a recess. It is. The concavo-convex part formed in this way is more likely to condense than a smooth part.

  In the second method, the acceleration voltage of the electron gun 3 is set to a low value, the target site on the surface of the sample 13 is irradiated intensively without scanning the electron beam, the contamination component is locally attached, and the nucleus and It is a method to do. In this case, when the size of the applied nucleus is sufficiently smaller than the droplet attached to the nucleus, the wetting angle can be measured without being affected by the nucleus.

  Subsequently, moisture is introduced from the gas introduction unit 20 to adjust the degree of vacuum to about 1000 Pa.

  Furthermore, the temperature of the toner particles is lowered using the temperature adjusting mechanism of the sample holder 14. As a result, the introduced gas (water) is condensed on the surface of the toner particles.

  Depending on the state of the sample surface, there are optimum values for the degree of vacuum in the sample chamber 2 and the temperature of the sample. This can be achieved by growing condensation while observing the reflected electron image and growing droplets with the optimum diameter. In the present embodiment, a droplet having a diameter of 300 nm is grown around the condensation nucleus that has been previously produced.

  Further, when observing a droplet, an optimum observation direction may be determined using the tilt / rotation function of the sample holder 14.

  In the present embodiment, it is possible to observe a water droplet having a diameter of 300 nm attached to the surface of the toner particle having a diameter of 1 μm by the above procedure, and it becomes possible to directly measure the wetting angle of the water droplet attached to the surface of the toner particle. .

  According to this method, even for a relatively large specimen such as a device, it becomes possible to evaluate the difference and distribution of the wetting angle in a local fine portion.

  In the present embodiment, moisture is introduced, but the present invention is not limited to this. For example, by introducing an arbitrary solvent, the wetting angle of the solvent can be measured.

(Second Embodiment)
FIG. 2 is a block diagram showing a second embodiment of the present invention.

  The difference from the first embodiment is that a sample chamber 22 having a mechanism that allows the electron optical column 1 and the backscattered electron detector 12 to move within a spherical surface centering on the sample is employed. Is the same as FIG.

  In this embodiment, since the tilt / rotation mechanism of the sample holder 14 is not required when observing the sample or droplet, the function of the sample holder 14 can be limited to position control and temperature control, and the structure is simpler. It becomes possible to make things.

The block diagram which shows the 1st Embodiment of this invention The block diagram which shows the 2nd Embodiment of this invention

Explanation of symbols

1 Electro-optical column 2 Sample chamber (sample chamber)
DESCRIPTION OF SYMBOLS 3 Electron gun 4 Electron gun chamber 5 Condenser lens 6 Scan coil 7 Astigmatism correction device 8 Objective lens 9 Lens chamber 10 Orifice 11 Orifice (object aperture)
12 Backscattered electron detector 13 Sample 14 Sample holder 15 Preliminary exhaust chamber 16, 17, 18, 19 Exhaust section 20 Gas introduction section 22 Sample chamber (sample chamber)

Claims (9)

A sample chamber capable of controlling the atmosphere, a sample holder for holding the sample introduced into the sample chamber and controlling the temperature of the introduced sample;
A scanning electron microscope for observing the sample held in the sample holder;
An electron gun driving means for irradiating an electron beam intensively on the sample surface from the electron gun of the scanning electron microscope to give a nucleus for condensing liquid on the sample surface; An apparatus for acquiring information on the wetting angle of a sample to be liquid.   The scanning electron microscope includes a lens barrel including an electron gun chamber having an electron gun and a lens chamber having a plurality of lenses, and a reflected electron detector for detecting reflected electrons from a sample, each of the two chambers being The apparatus for acquiring information on the wetting angle of the sample with respect to the liquid according to claim 1, wherein the degree of vacuum is adjusted to be different by an individual exhaust system.   3. The degree of vacuum in the sample chamber is adjusted to an arbitrary set value by controlling both a valve and an exhaust system of a gas introduction path for a liquid component. An apparatus for acquiring information on the wetting angle of the sample with respect to the liquid.   4. The sample liquid according to claim 1, wherein the sample temperature on the sample holder is adjusted to an arbitrary set value by externally controlling both heating and cooling mechanisms. Acquiring device about the wetting angle with respect to.   The said sample holder has an inclination and rotation mechanism in addition to a movement of a sample position, The information acquisition apparatus regarding the wetting angle with respect to the liquid of the sample in any one of Claims 1-4 characterized by the above-mentioned.   2. The apparatus according to claim 1, further comprising means for changing the positions of the column and the backscattered electron detector of the scanning electron microscope so that the tube and the backscattered electron detector are opposed to the sample surface. 5. An apparatus for acquiring information relating to the wetting angle of the sample according to any one of 4 above.   A sample is held in a sample chamber where the atmosphere can be controlled, and an electron beam is intensively applied to the sample surface from an electron gun of a scanning electron microscope to provide a nucleus for condensing liquid on the sample surface. A method for acquiring information relating to a wetting angle of a sample with respect to a liquid, comprising growing a droplet on the sample surface and observing the sample with a scanning electron microscope.   The method for acquiring information on the wetting angle of the sample with respect to the liquid according to claim 7, wherein the observation of the sample with a scanning electron microscope is performed from an arbitrary direction by tilting and rotating the sample holder.   The observation of the sample by a scanning electron microscope is performed by making a lens barrel and a backscattered electron detector of the scanning electron microscope movable and facing the sample from an arbitrary direction. A method for obtaining information on the wetting angle of the sample with respect to the liquid.

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