JP2007114015A - Humidity measuring instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small-sized humidity measuring instrument capable of measuring the humidity in a vacuum chamber or the like with high precision. <P>SOLUTION: The humidity measuring instrument 3 is constituted so as to measure the ambient humidity in the vacuum chamber 2 or the like and equipped with: an inspection member 6 having a gap in which a water molecule gets in the ratio corresponding to the difference of the ambient humidity; the vibration part 7 having the inspection member 6 attached thereto and vibrated along with the inspection member 6; a drive part 11 or 14 for vibrating the vibration part 7 at a set frequency; and a measuring part 12 or 15 for indirectly measuring humidity by measuring the vibration frequency of the vibration part 7 shifted from the set frequency by the change in the mass of the inspection member 6 proportional to the humidity caused by the change in the amount of moisture getting in the gap corresponding to a change in the ambient humidity. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a humidity measuring apparatus for measuring ambient humidity, and more particularly to a humidity measuring apparatus suitable for use in measuring humidity in a vacuum chamber that affects the refractive index of a film material formed by vacuum deposition.

  For example, vacuum deposition is a process of evaporating a material such as metal in a vacuumed vacuum chamber to form a deposited film on the surface of an object. Specifically, an object for forming a film material is mounted in a vacuum chamber and evacuated, the material of the film material is evaporated, and the evaporated material is laminated on the surface of the object. Thereby, a uniform vapor deposition film is formed on the surface of the object.

  By the way, in a general vacuum vapor deposition apparatus, only a control for forming a vapor deposition film having a uniform set film thickness is performed, and a difference in humidity is not particularly taken into consideration. Regarding the difference in humidity, it was not specified as a specific object of control of the apparatus because the operator checked the humidity before performing the vacuum evaporation operation and made fine adjustments. This is because there has been no problem with accuracy until now even if humidity is not taken into consideration.

  However, with the recent improvements in precision and accuracy of various optical instruments, there has been a problem of changes in the refractive index of the deposited film due to changes in the humidity in the vacuum chamber. That is, when forming a vapor deposition film with a vacuum vapor deposition device, the refractive index of the vapor deposition film slightly changes due to the difference in humidity in the vacuum chamber, and the accuracy of the optical equipment using the component on which the vapor deposition film is applied is improved. The problem of decline has arisen.

  In addition, when forming a vapor deposition film with a vacuum vapor deposition apparatus, a refractive index changes for the following reasons. When the material is evaporated in the vacuum chamber and adhered to the surface of the object, water molecules existing in the vacuum chamber together with the evaporated material also enter the deposited film. The amount of water molecules entering the deposited film is determined according to the water molecular weight (humidity) in the vacuum chamber. This water molecular weight changes with the addition of water molecules that jump out of the inner wall of the vacuum chamber as the material evaporates. And the refractive index of a vapor deposition film will also change according to the water molecular weight which entered the vapor deposition film. The change in water molecular weight after this deposition operation has started has not been taken into account since it cannot be measured.

  However, the refractive index of the deposited film, which changes due to the slight difference in water molecular weight (humidity), has become a problem due to the recent refinement and high precision of optical instruments.

  For this reason, it has become necessary to provide a device for measuring the humidity in the vacuum chamber in the vacuum vapor deposition device, but it is small enough to be incorporated into the vacuum vapor deposition device and can measure a small amount of water molecule (humidity) in the vacuum chamber. There has never been a highly accurate humidity measurement device.

  The present invention has been made in view of the above points, and it is an object of the present invention to provide a small-sized humidity measuring apparatus capable of measuring a slight change in humidity in a vacuum chamber or the like with high accuracy.

  In order to solve the above problems, a humidity measuring apparatus according to the present invention is a humidity measuring apparatus for measuring ambient humidity, and has an inspection member having a gap into which water molecules enter at a ratio corresponding to a difference in ambient humidity. A vibration unit that is attached to the inspection member and vibrates with the inspection member, a drive unit that vibrates the vibration unit at a set frequency, and a water molecular weight that enters the gap changes according to a change in ambient humidity. And a measurement unit that measures the humidity indirectly by measuring the vibration frequency of the vibration unit that varies in proportion to the humidity and thereby deviates from the set frequency. .

  With the above configuration, the inspection member absorbs water molecules at a ratio corresponding to the difference in ambient humidity, and changes to a mass proportional to the ambient humidity. As a result, the vibration frequency of the vibration unit is deviated from the set frequency in accordance with the change in the mass, and the measurement unit measures the amount of deviation and indirectly measures the humidity.

  The inspection member is preferably a metal, oxide, fluoride, or sulfide film formed by being laminated on the surface of the vibrating portion. It is desirable that the vibration unit includes a piezoelectric material that vibrates in response to a voltage applied at the set frequency. The piezoelectric material is preferably a quartz crystal vibrator that vibrates at a high frequency. Moreover, it is desirable that the humidity measuring device according to the present invention measures the humidity in the vacuum chamber.

  As a result, a metal, oxide, fluoride, or sulfide film (for example, a titanium oxide or silicon oxide film) absorbs water molecules at a ratio corresponding to the difference in ambient humidity, and the ambient humidity is obtained. It changes to a proportional mass. In the vibration unit, the piezoelectric substance such as a quartz vibrator can be set to vibrate at a set frequency, particularly at a high frequency, so that the frequency is greatly shifted even with a slight difference in mass.

  Detecting even a slight change in mass by measuring the amount of vibration frequency deviation of the vibration part that shifts as the test member absorbs water molecules and changes in mass to indirectly measure humidity. And a slight change in humidity can be measured.

  In particular, by making the inspection member a metal, oxide, fluoride or sulfide film (for example, a titanium oxide or silicon oxide film), water molecules are efficiently absorbed, and the ambient humidity changes. The mass can be changed in proportion to the ambient humidity. In addition, in the above-described vibration unit, a piezoelectric substance such as a crystal resonator can be set so that the frequency greatly deviates even with a slight difference in mass by vibrating at a set frequency, particularly at a high frequency. Changes can be measured. As a result, even a slight change in humidity in a vacuum chamber or the like can be measured with high accuracy.

  Moreover, since the measurement part is composed of a small vibration part such as a crystal resonator and an inspection member attached to the vibration part by lamination or the like, the measurement part can be reduced in size, and a vacuum deposition apparatus or the like is narrow. It can be easily incorporated into space.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  The humidity measuring apparatus of the present invention can be used for humidity measurement in a space where a slight change in humidity needs to be measured. In particular, the humidity measuring device is suitable for use in measuring humidity in a space such as a vacuum chamber where few water molecules exist. Here, an example in which the humidity measuring device is used in a vacuum vapor deposition device will be described with reference to FIG. FIG. 1 is a schematic configuration diagram showing a vacuum deposition apparatus provided with a humidity measuring apparatus according to the present embodiment.

  The vacuum vapor deposition apparatus 1 in the figure is a generally known apparatus. For this reason, the vacuum evaporation apparatus 1 is demonstrated roughly. The vacuum deposition apparatus 1 mainly includes a heating means (not shown) for heating the material to be evaporated, a crucible (not shown) for storing the material to be evaporated, a substrate (not shown) as a deposition target, and a vacuum. A chamber 2, a humidity measuring device 3 for measuring the humidity in the vacuum chamber 2, and a control for controlling calculation of measured values in the humidity measuring device 3, evacuation in the vacuum chamber 2, film thickness adjustment of the deposited film, etc. Part 4 and the like.

  The crucible is for containing a metal material to be evaporated. A heating means is a means for evaporating the material put into the crucible. The heating means is composed of an electron gun, an electron current adjusting unit (both not shown), and the like. The substrate which is a vapor deposition target is a target member which applies a vapor deposition film on its surface.

  The vacuum chamber 2 is a space for performing vacuum deposition. The inside of the vacuum chamber 2 is evacuated, and vacuum deposition work is performed.

  The humidity measuring device 3 is a device for measuring the humidity in the vacuum chamber 2. As shown in FIG. 2, the humidity measuring device 3 mainly includes an inspection member 6, a vibrating unit 7, a driving unit 11 or 14, and a measuring unit 12 or 15.

  The inspection member 6 is a material having a void into which water molecules enter at a ratio corresponding to a difference in ambient humidity. The inspection member 6 indirectly measures the humidity in the vacuum chamber 2. The inspection member 6 has a gap through which water molecules enter and exit, and water molecules enter at a ratio corresponding to the difference in ambient humidity, and the mass changes due to the difference in the amount of water molecules entering the gap. ing. That is, the mass of the inspection member 6 changes in proportion to the difference in humidity in the vacuum chamber 2. As a result, the humidity in the vacuum chamber 2 and the mass of the inspection member 6 are in a proportional relationship. For this reason, the change in the humidity in the vacuum chamber 2 can be indirectly measured by measuring the change in the mass of the inspection member 6 disposed in the vacuum chamber 2.

  The inspection member 6 is provided by being laminated on the upper surface of the vibration part 7. Specifically, the inspection member 6 is composed of a titanium oxide or silicon oxide film formed by being laminated on the upper surface of the vibration part 7. These members are materials that easily form voids having a size that allows the number of water molecules present in the surrounding area to be taken in and released in proportion to the density. By providing such a porous inspection member 6 having a large number of voids on the upper surface of the vibration part 7, a vibrator whose mass changes in proportion to the difference in humidity is configured. The shape of the inspection member 6 provided on the upper surface of the vibration part 7 is an aspect that can most effectively affect the vibration of the vibration part 7. Since the shape of the inspection member 6 varies depending on various conditions such as the specific dimensions and shape of the vibration portion 7, various shapes such as a disk shape, a triangular shape, a quadrangular shape, and a donut shape are used according to each vibration portion 7. The shape is appropriately set. Moreover, the test | inspection member 6 is comprised by one member of a specific shape, or is comprised combining several small things. That is, the inspection member 6 is provided in such a manner that the change in mass due to the absorption of water molecules can be most effectively affected by the change in the vibration frequency of the vibration part 7. The material of the inspection member 6 is not limited to a titanium oxide or silicon oxide film, but is a metal, oxide, fluoride or sulfide film, in which water molecules are present at a ratio corresponding to the difference in ambient humidity. Any material can be used as long as it can form the entrance and exit gaps.

  The vibration part 7 is a member that is attached with the inspection member 6 and vibrates together with the inspection member 6. The vibrating portion 7 is made of a piezoelectric material that vibrates in response to a voltage applied at a set frequency. As the piezoelectric material, piezoelectric ceramics obtained by compressing and firing a metal oxide powder such as barium titanate, a crystal resonator, and the like can be used. In the case of a crystal resonator, various types of crystal resonators such as an AT cut type, a BT cut type, and a tuning fork type can be used. Here, an AT-cut type crystal resonator is used as the piezoelectric material. This AT-cut type crystal resonator is vibrated at a high frequency. The vibrating part 7 has a spherical upper surface, and an inspection member 6 is laminated on the upper surface of the spherical surface. The vibration part 7 is mounted in the vacuum chamber 2. Other circuits such as the drive unit 11 or 14 are provided outside the vacuum chamber 2. An electrode layer (not shown) is provided on each of the upper side surface and the lower side surface of the vibration part 7.

  The drive unit 11 or 14 is a circuit for causing the vibration unit 7 to vibrate at a set frequency. The measurement unit 12 or 15 is a circuit for measuring the vibration frequency of the vibration unit 7 vibrated by the drive unit 11 or 14. As a circuit that vibrates the vibration unit 7 and a circuit that measures the vibration frequency of the vibration unit 7, various commonly used circuits can be used. Here, two examples of a circuit based on the transmission method 8 and a circuit based on the transmission method 9 are shown. One of the circuits can measure the vibration and vibration frequency of the vibration unit 7.

  As the drive unit 11 or 14, any circuit that can apply a high frequency voltage to the crystal resonator of the vibration unit 7 to vibrate the crystal resonator at a high frequency can be used. Here, an oscillator is used as an example of the drive unit 11 of the transmission method 8. As an example of the driving unit 14 of the transmission method 9, a π circuit is used.

  As the measurement unit 12 or 15, any circuit that can measure high-frequency vibrations of the crystal unit of the vibration unit 7 can be used. Here, a counter is used as an example of the measuring unit 12 of the transmission method 8. As an example of the measurement unit 15 of the transmission method 9, a network analyzer is used.

  The vibration unit 7 is configured to vibrate at a set frequency when the drive unit 11 or 14 applies a voltage having a set frequency to the vibration unit 7. When the drive unit 11 or 14 has a reference humidity (for example, 1% humidity), the vibration unit 7 including the inspection member 6 having a mass proportional to the humidity may vibrate at a set frequency. A voltage having a frequency adjusted to be able to be applied is applied. As a result, the vibration unit 7 vibrates at the set frequency when the driving unit 11 or 14 applies a voltage of the adjusted set frequency to the vibration unit 7 at the reference humidity. When the humidity becomes high, the vibration frequency of the vibration unit 7 shifts in a direction lower than the set frequency, and when the humidity is low, the vibration frequency of the vibration unit 7 becomes higher than the set frequency. It shifts in the direction. Then, by measuring this shifted vibration frequency, the ambient humidity is indirectly measured.

  Further, the vibration unit 7 is vibrated at a high frequency. This is because the shift in wavelength can be increased even with a slight change in mass by using a high frequency. Thereby, a change in humidity can be measured with high accuracy.

  The measurement unit 12 or 15 measures the vibration frequency of the vibration unit 7 that deviates from the set frequency in order to indirectly measure the humidity. The measurement unit 12 or 15 measures the vibration frequency of the vibration unit 7 and indirectly measures the humidity from a value obtained by subtracting the set frequency from the vibration frequency. The measuring unit 12 or 15 is provided with a storage area such as a memory (not shown). In this storage area, the relationship between the deviation of the vibration frequency of the vibration unit 7 from the set frequency and the humidity is recorded. That is, the relationship between the value obtained by subtracting the set frequency from the vibration frequency of the vibration unit 7 and the humidity in the vacuum chamber 2 is experimentally specified in advance, and the relationship is recorded in the storage area. As a result, the mass of the water in the inspection member 6 changes in proportion to the humidity due to the change in the molecular weight of water entering the gap of the inspection member 6 in accordance with the change in the humidity of the vacuum chamber 2. The vibration frequency of the unit 7 is measured, and the humidity is indirectly measured from a value obtained by subtracting the set frequency from the vibration frequency. The subtracting circuit for subtracting the set frequency from the vibration frequency and the memory may be provided in the control unit 4.

  The control unit 4 resets the film thickness of the vapor deposition film to a thickness that corrects the deviation from the reference humidity based on the measurement value in the measurement unit 9, and forms the vapor deposition film with the film thickness. It has become.

[Operation]
In the vacuum vapor deposition apparatus 1 configured as described above, the vapor deposition film of the substrate is formed as follows.

  A crucible and a substrate are mounted in the vacuum chamber 2 and the inside of the vacuum chamber 2 is evacuated, and the material in the crucible is heated and evaporated by the heating means, and deposited on the surface of the substrate. This vapor deposition operation is a common one performed by the vacuum vapor deposition apparatus 1. At this time, the film thickness of the vapor deposition film formed on the substrate is set to a thickness corresponding to the humidity in the vacuum chamber 2. The film thickness of this deposited film is set by the following process.

  First, the vibration unit 7 in the vacuum chamber 2 is vibrated at a set frequency by the drive unit 11 or 14, and the vibration frequency of the vibration unit 7 is measured by the measurement unit 12 or 15. Next, the measurement frequency is subtracted from the measured vibration frequency by the measurement unit 12 or 15, and the humidity is determined from the subtraction value with reference to data in the memory (relationship between the subtraction value and the humidity in the vacuum chamber 2). Identified.

  The control unit 4 corrects the film thickness of the vapor deposition film from the relationship between the intensity of reflected light specified in advance and the humidity in the vacuum chamber 2 and the relationship between the change in humidity and the correction of the film thickness of the vapor deposition film. Identify the minutes.

  Subsequently, the control part 4 controls each part of the vacuum evaporation system 1, and sets it again to the film thickness containing the correction | amendment specified from the said humidity, and forms a vapor deposition film.

[effect]
As described above, since the change in the humidity in the vacuum chamber 2 is detected as the change in the frequency due to the change in the water molecules in the inspection member 6, the humidity in the vacuum chamber 2 can be indirectly measured with high accuracy.

  Since the inspection member 6 absorbs water molecules and changes the mass, the deviation of the vibration frequency of the vibrating part 7 is measured and the humidity is indirectly measured, so that a slight change in mass is also detected. And a slight change in humidity can be measured. As a result, a change in humidity in the vacuum chamber 2 can be easily detected.

  In particular, by making the inspection member 6 a titanium oxide or silicon oxide film, water molecules are efficiently absorbed, and the change in the mass proportional to the ambient humidity is achieved by following the change in the ambient humidity. Therefore, it becomes possible to indirectly detect a change in humidity with high accuracy.

  Moreover, since the vibration part 7 is vibrated at high frequency, it can be set so that the frequency is greatly shifted even with a slight difference in mass, and a slight change in humidity can be measured with high accuracy. As a result, even a slight change in humidity in the vacuum chamber 2 can be measured with high accuracy.

  Further, since the measurement part is composed of the small vibration part 7 made of a crystal resonator and the inspection member 6 provided by being laminated on the vibration part 7, the measurement part can be reduced in size, and the vacuum evaporation apparatus Thus, it can be easily incorporated into a narrow space such as the vacuum chamber 2.

[Modification]
In the above embodiment, the drive unit 8 and the like of the humidity measuring device 3 are provided outside the vacuum chamber 2. However, if there is a space in the vacuum chamber 2, the drive unit 11 or 14 or the like is placed in the vacuum chamber 2. It may be provided. Also in this case, the same operations and effects as the above embodiment can be achieved.

  Moreover, in the said embodiment, although the humidity measuring apparatus 3 which measures the humidity in the vacuum chamber 2 of the vacuum evaporation system 1 was demonstrated to the example, it uses for the general use which needs to measure a slight change of humidity with high precision. be able to.

It is a schematic structure figure showing the vacuum evaporation system concerning the embodiment of the present invention. It is a block diagram which shows a humidity measuring apparatus.

Explanation of symbols

1: vacuum deposition device, 2: vacuum chamber, 3: humidity measurement device, 4: control unit, 6: inspection member, 7: vibration unit, 8: drive unit, 9: measurement unit, 11: oscillator, 12: counter, 14: π circuit, 15: network analyzer.

Claims (6)

A humidity measuring device for measuring ambient humidity,
An inspection member having a void into which water molecules enter at a ratio according to the difference in ambient humidity;
A vibration part attached with the inspection member and vibrating with the inspection member;
A drive unit for vibrating the vibration unit at a set frequency;
By measuring the vibration frequency of the vibration part that deviates from the set frequency by changing the mass of the inspection member in proportion to the humidity by changing the molecular weight of water entering the gap according to the change in ambient humidity. A humidity measuring apparatus comprising a measuring unit for indirectly measuring humidity. The humidity measuring device according to claim 1,
The humidity measuring apparatus, wherein the inspection member is a metal, oxide, fluoride or sulfide film formed by being laminated on the surface of the vibration part. In the humidity measuring device according to claim 1 or 2,
The humidity measuring apparatus, wherein the vibration section includes a piezoelectric substance that vibrates in response to a voltage applied at the set frequency. In the humidity measuring device according to claim 3,
A humidity measuring apparatus, wherein the piezoelectric substance is a crystal resonator. In the humidity measuring device according to any one of claims 1 to 4,
A humidity measuring apparatus, wherein the vibration section vibrates at a high frequency. In the humidity measuring device according to any one of claims 1 to 5,
A humidity measuring apparatus, wherein a vibration part to which the inspection member is attached is mounted in a vacuum chamber and measures the humidity in the vacuum chamber.

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