JP2011069630A - Permittivity measuring method and measuring apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a permittivity measuring method and measuring apparatus which can improve the resolution of the permittivity of a sample by increasing the detection value of the resonance frequency of a near-field electromagnetic wave. <P>SOLUTION: The permittivity measuring method includes: the process for bringing an electrically conductive board having higher conductivity than the sample 14 into intimate contact with one surface of the sample 14; the process for bringing the other surface of the sample 14 into intimate contact with a radiation surface 11b of a probe resonator 3; the process for radiating the near-field electromagnetic wave from the radiation surface 11b of the probe resonator 3; the process for detecting the resonance frequency of the near-field electromagnetic wave; and the process for determining the permittivity of the sample 14 on the basis of the resonance frequency. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for measuring the dielectric constant of an object, and more specifically to a dielectric constant measurement method using a probe resonator that irradiates near-field electromagnetic waves, and a dielectric constant measurement apparatus.

  In recent years, with the speeding up of electronic devices and the trend toward wireless, in the development of products related to high-frequency electromagnetic waves, the dielectric constant characteristics of materials, especially the dielectric constant and dielectric loss tangent (tan δ) have become important design information. Although the physical property values provided by material manufacturers may be used as a guideline for such dielectric constant characteristics, it is difficult to obtain dielectric constant data for the frequencies actually used. In some cases, it may be necessary to estimate from data on low frequencies. Therefore, a technique for measuring the dielectric constant of the material is required.

  Conventionally, a method using a microwave resonator is known as a method for measuring a dielectric constant. Specifically, there is a method of irradiating a subject with near-field electromagnetic waves using a probe resonator and measuring the dielectric constant of the subject. Here, the near-field electromagnetic wave is an electromagnetic wave that leaks out around the hole and stops at that position when the electromagnetic wave is radiated into a hole that is sufficiently smaller than its wavelength. When such a near-field electromagnetic wave is irradiated to a dielectric, the resonant frequency of the near-field electromagnetic wave varies depending on the dielectric constant of the dielectric, so the dielectric constant should be measured based on the variation in the resonant frequency. Can do.

  For example, in Patent Document 1, a sample is brought into contact with the end face of a probe for irradiating a high-frequency microwave, a voltage of a reflected wave from the sample is detected, and a value corresponding to a change in resonance frequency is obtained by Fourier transform. Discloses a method of measuring the dielectric constant of a sample by calculating.

Japanese Patent Laying-Open No. 2005-121422

  However, when the tip surface of the probe is simply brought into contact with the sample as in the measurement method of Patent Document 1, when the relative dielectric constant of the sample is low (for example, when the relative dielectric constant is smaller than 4), the dielectric of the sample Since the detected value of the resonance frequency of the near-field electromagnetic wave proportional to the rate (capacitance) is also small, it is difficult to increase the measurement resolution.

  In particular, in recent years, it has been desired to measure the dielectric constant of a micron-order thin film (for example, a thin film used as an insulator portion of a semiconductor wiring) used in a semiconductor device or the like. Since the dielectric constant is low due to its thinness, it is very difficult to measure the dielectric constant with high accuracy.

  The present invention has been made in view of the above problems, and when measuring the dielectric constant of a sample using near-field electromagnetic waves, the dielectric constant of the sample is measured with high accuracy even if the dielectric constant of the sample is small. It is an object of the present invention to provide a dielectric constant measuring method and a dielectric constant measuring apparatus capable of performing the above.

  In order to solve the above-described problems, the present invention provides a method for measuring a dielectric constant of a sample using a probe resonator having a radiation surface capable of emitting near-field electromagnetic waves, and having a conductivity higher than that of the sample. Forming a capacitance between the conductive member and the probe resonator by bringing the conductive member having a contact surface and the radiation surface of the probe resonator into close contact with the sample in a direction opposite to each other. A step of radiating near-field electromagnetic waves from the radiation surface of the probe resonator while performing the forming step, and a book for detecting the resonance frequency of the near-field electromagnetic waves while performing the radiating step There is provided a method for measuring a dielectric constant, comprising: a detecting step; and a specifying step of specifying a dielectric constant of the sample based on a resonance frequency detected by the main detecting step.

  According to the present invention, since the near-field electromagnetic wave is radiated in a state where the sample is sandwiched between the conductive member and the radiation surface of the probe resonator, the detected value of the resonance frequency of the near-field electromagnetic wave can be increased. . Specifically, the resonance frequency of the near-field electromagnetic wave is a value proportional to the capacitance of the probe resonator that varies according to the dielectric constant of the closely contacted sample. By disposing the conductive member between the conductive member and the probe resonator having conductivity, the capacitance between the conductive member and the probe resonator (hereinafter referred to as external capacitance) is the probe resonance. Will be added as part of the capacitance of the vessel. That is, in the present invention, since the external capacitance is apparently added to the capacitance of the probe resonator that determines the resonance frequency, the value of the resonance frequency of the near-field electromagnetic wave can be increased by the amount of the external capacitance. it can.

  Therefore, according to the present invention, the dielectric constant of the sample can be measured with high accuracy by increasing the value of the resonance frequency of the near-field electromagnetic wave.

  In the dielectric constant measurement method, in the forming step, it is preferable that the conductive substrate and the sample are brought into close contact with each other by forming a thin film of the sample on a conductive substrate as the conductive member.

  According to this measurement method, it is possible to measure the dielectric constant of a thin film (for example, an insulator on a circuit board) formed on a conductive substrate.

  In the dielectric constant measurement method, the radiation surface of the probe resonator and the contact surface of the sample that is in close contact with the radiation surface are flat surfaces, and are flush with the radiation surface of the probe resonator. A positioning member having a flat surface disposed so as to be positioned at the position, and in the forming step, the positioning member is positioned so that the contact surface of the sample is in close contact with the flat surface of the positioning member. The sample and the probe resonator are preferably brought into close contact with each other by bringing the close contact surface of the sample into close contact with the radiation surface.

  According to this measurement method, since the radiation surface of the probe resonator and the flat surface of the positioning member are located on the same plane, even a sample having a contact surface larger than the radiation surface can be used. It is possible to bring the contact surface into close contact with the radiation surface while positioning the portion that protrudes outside the radiation surface in close contact with the flat surface.

  In the method for measuring a dielectric constant, a radiation position for radiating the near-field electromagnetic wave is set in advance on a radiation surface of the probe resonator, and in the forming step, the conductive material includes a portion overlapping the radiation position. It is preferable to apply a predetermined load toward the probe resonator to at least a part of the member.

  According to this measurement method, when a sample having a contact surface larger than the radiation surface is adhered to the probe resonator, that is, when the sample is adhered to a wide range of the radiation surface and the flat surface, It is possible to suppress the near-field electromagnetic wave radiation target position from floating from the radiation surface. Therefore, according to the above method, it is possible to improve the measurement accuracy of the resonance frequency by facilitating the close contact between the sample and the radiation surface while facilitating the close contact of the large sample.

  In the dielectric constant measurement method, the radiation surface and the flat surface of the probe resonator are respectively arranged upward, and in the forming step, the contact is made to the radiation surface and the flat surface arranged upward. It is preferable that the contact surface is in close contact with the radiation surface while the sample is placed with the surface facing downward.

  According to this measurement method, with the sample placed on the radiation surface and flat surface arranged upward, the measurement target portion of the sample contact surface and the radiation position of the near-field electromagnetic wave can be easily aligned. can do.

  The dielectric constant measurement method further includes a preliminary detection step of detecting a resonance frequency for a sample having a known dielectric constant. In the specific step, the resonance frequency detected in the preliminary detection step and the main detection step It is preferable to identify the unknown dielectric constant by comparing it with the detected resonance frequency.

  According to this measurement method, the accuracy of dielectric constant measurement can be further improved by detecting the resonance frequency in advance for a large number of samples having different dielectric constants in the preliminary detection step.

  Further, the present invention is an apparatus for measuring the dielectric constant of a sample, and is disposed on the same plane as a probe resonator having a radiation surface capable of emitting near-field electromagnetic waves, and the radiation surface of the probe resonator. A positioning member having a flat surface, and a radiation surface of the probe resonator is a flat surface, and the probe resonator and the positioning member are disposed such that the radiation surface and the flat surface are upward. An apparatus for measuring a dielectric constant is provided.

  According to the present invention, there is provided a measuring apparatus capable of adopting the above-described measuring method in which a sample is brought into close contact with the radiation surface of the probe resonator and a conductive member is brought into close contact with the sample from the side opposite to the radiation surface. Obtainable.

  Specifically, according to the measuring apparatus according to the present invention, since the radiation surface of the probe resonator and the flat surface of the positioning member are located on the same plane, even if the sample is larger than the radiation surface, The portion of the sample that protrudes from the radiation surface can be brought into close contact with the flat surface, and the sample can be brought into close contact with the radiation surface.

  The measurement apparatus preferably further includes a load addition unit that is provided on the base and applies a predetermined load toward the radiation surface side with respect to the sample placed on the radiation surface.

  According to this configuration, when a sample larger than the radiation surface is in close contact with the probe resonator, that is, when the sample is in close contact with a wide range of the radiation surface and the flat surface, the radiation position of the near-field electromagnetic wave in the sample Can be prevented from floating from the radiation surface. Therefore, according to the above method, it is possible to improve the measurement accuracy of the resonance frequency by facilitating the close contact between the sample and the radiation surface while facilitating the close contact of the large sample.

  According to the present invention, even if the dielectric constant of a sample is small, the dielectric constant of the sample can be measured with high accuracy.

It is the schematic which shows the measuring apparatus 1 of the dielectric constant which concerns on embodiment of this invention. It is side surface sectional drawing of the probe resonator 3 of FIG. It is sectional drawing which expands and shows a part of FIG. 2, and shows before mounting | wearing with a sample. It is sectional drawing which expands and shows a part of FIG. 2, and shows the state which mounted | wore the sample. It is a graph which shows the relationship between the dielectric constant of a sample, and the shift | offset | difference of a resonant frequency, and shows the case where a silicon substrate (no dopant) is employ | adopted as a board | substrate which adhere | attaches a sample. It is a graph which shows the relationship between the dielectric constant of a sample, and the shift | offset | difference of a resonant frequency, and shows the case where an aluminum substrate is employ | adopted as a conductive substrate.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing a dielectric constant measuring apparatus 1 according to an embodiment of the present invention.

  Referring to FIG. 1, a measuring apparatus 1 includes a probe resonator 3 that emits near-field electromagnetic waves, a base that holds the probe resonator 3, and an oscillator 4 that supplies high-frequency power to the probe resonator 3. , An analyzer 5 for analyzing an electrical signal taken out from the probe resonator 3, and a control device 6 electrically connected to the oscillator 4 and the analyzer 5.

  FIG. 2 is a side sectional view of the probe resonator 3 of FIG.

  With reference to FIGS. 1 and 2, the probe resonator 3 includes an outer conductor 7 and an inner conductor 8 provided inside the outer conductor 7. In the probe resonator 3, the outer conductor 7 and the inner conductor 8 are provided coaxially, and both the conductors 7, 8 are short-circuited on the lower end side, so that both the conductors 7, 8 are arranged coaxially. It is a resonator that generates a resonance phenomenon corresponding to the length of the current.

  The outer conductor 7 includes a cylindrical portion 9 and a lower lid body 10 and an upper lid body 11 fixed to the cylindrical portion 9 so as to close the upper and lower openings of the cylindrical portion 9. The cylindrical portion 9 is a metal member formed in a cylindrical shape. The lower lid body 10 is a disk-shaped metal member fixed to the lower end surface of the cylindrical portion 9 so as to close the lower opening of the cylindrical portion 9. The lower end portion of the inner conductor 8 is fixed to the substantially center position of the lower lid body 10 by a bolt B2. Further, the lower lid 10 is provided with a signal introducing unit 12A that receives supply of high-frequency power from the oscillator 4 and a signal extraction unit 12B that outputs a signal to the analyzer 5. Each of the signal introduction part 12A and the signal extraction part 12B is for connection with a coaxial cable, and includes a cylindrical outer conductor 12a and an inner conductor 12b provided inside the outer conductor 12a. The outer conductor 12 a is fixed to the lower surface of the lower lid 10 and is electrically connected to the lower lid 10. The inner conductor 12b extends to the inside of the cylindrical portion 9 through a hole penetrating the inner side of the outer conductor 12a and the lower lid 10, and is electrically connected to the lower lid 10 by making a U-turn. The U-turn portion of the inner conductor 12b functions as a loop antenna. The upper lid body 11 is a disk-shaped metal member fixed to the upper end surface of the cylindrical portion 9 with a bolt B1 so as to close the upper opening of the cylindrical portion 9. A hole 11 a penetrating vertically is formed at a substantially central position of the upper lid body 11. Since the diameter of the hole 11a is set to be smaller than the wavelength of the electromagnetic wave generated in the probe resonator 3, a part of the electromagnetic wave that cannot pass through the hole 11a is generated in the vicinity of the hole 11a as a near-field electromagnetic wave. Will do. In the present embodiment, the upper surface 11b of the upper lid body 11 provided with the hole 11a constitutes a radiation surface that radiates near-field electromagnetic waves. On the other hand, on the lower surface of the upper lid 11, a tapered concave portion is formed which expands as it proceeds downward from the hole 11a. In the present embodiment, the outer conductor 7 is entirely formed of metal. However, the outer conductor 7 is a material having a high conductivity only on the surface (including the inner surface) (for example, metal). It can also be set as the structure which consists of material (for example, synthetic resin) with small electroconductivity inside.

  The inner conductor 8 is a rod-shaped metal member provided coaxially with the cylindrical portion 9 of the outer conductor 7. Specifically, the inner conductor 8 is erected at a substantially central position of the lower lid body 10 of the outer conductor 7. The tip of the inner conductor 8 has a tapered shape that becomes thinner as it travels upward, and is disposed in the hole 11 a of the upper lid 11. Here, the tip of the inner conductor 8 may protrude above the upper surface (radiation surface) 11b of the upper lid 11, but the sample 14 (see FIG. 3) is disposed on the radiation surface 11b as will be described later. However, from the viewpoint of avoiding contact with the sample 14, it is preferably disposed below the radiation surface 11 b, but the near-field electromagnetic wave is closer to the sample 14 than the tip of the inner conductor 8. From this point of view, it is most preferable to arrange at the same height as the radiation surface 11b.

  The base for holding the probe resonator 3 includes a positioning table (positioning member) 2 that holds the probe resonator 3 with the radiation surface 11b facing upward, and a leg portion that supports the positioning table 2. (Support part: not shown). The positioning table 2 has a flat surface 2a disposed on the same plane as the radiation surface 11b of the probe resonator 3. In other words, the positioning table 2 holds the probe resonator so that the flat surface 2a and the radiation surface 11b of the probe resonator are located on the same plane.

  The oscillator 4 is a high frequency power source connected to the signal introducing portion 12A of the probe resonator 3 via a coaxial cable.

  The analyzer 5 is connected to the signal extraction portion 12B of the probe resonator 3 via a coaxial cable, and resonates by observing the transmission attenuation of the frequency sweep signal based on the signal obtained from the probe resonator 3. The frequency is detected.

  The control device 6 adjusts the power supplied to the probe resonator 3 by the oscillator 4 and can exchange electric signals with the analyzer 5. Specifically, the control device 6 stores in advance data (see FIG. 6) relating to the shift of the resonance frequency measured in advance using the analyzer 5 for a sample having a known dielectric constant. The dielectric constant of the sample is specified based on the resonance frequency measured using the analyzer 5 for the sample having an unknown dielectric constant. Thus, the dielectric constant of the sample specified by the control device 6 is shown to the user by a display device or the like not shown.

  Hereinafter, a method for measuring the dielectric constant of the sample 14 using the measurement apparatus 1 will be described.

  FIG. 3 is an enlarged cross-sectional view of a part of FIG. 2 and shows a state before the sample 14 is mounted. FIG. 4 is an enlarged cross-sectional view showing a part of FIG. 2, and shows a state in which the sample 14 is mounted.

  With reference to FIGS. 2 to 4, first, a subject whose dielectric constant is to be measured will be described. In the present embodiment, a sample in which a thin film of the sample 14 is formed on the conductive substrate 15 is employed as the subject. The conductive substrate 15 is a conductive substrate (low resistance substrate) having a resistance value of 50 Ω × cm or less. In this embodiment, a metal substrate is used as the conductive substrate 15, but the present invention is not limited to this, and other substrates having a low resistance value (50Ω × cm or less) (for example, adding a dopant to a silicon substrate) Can also be adopted. The sample 14 is a thin film made of a material having lower conductivity than the conductive substrate 15. In the present embodiment, this sample 14 is a dielectric constant measurement target.

  When measuring the dielectric constant of the sample 14, first, the conductive substrate 15 having higher conductivity than the sample 14 and the radiation surface 11 b of the probe resonator 3 are opposed to the sample 14 from the opposite direction. By bringing them into close contact, a capacitance is formed between the conductive substrate 15 and the probe resonator 3 (forming step). Specifically, this formation process includes a first contact process and a second contact process described below.

  In the first adhesion step, a thin film of the sample 14 is formed on the conductive substrate 15 to create the subject. That is, in the first contact process, a test object in which the conductive substrate 15 and the sample 14 are in close contact with each other is created. This first adhesion step may be performed before the holding step and the attaching step.

  In the second contact step, the surface of the sample 14 opposite to the conductive substrate 15 (the lower surface in FIG. 4: the contact surface) is positioned so as to be in close contact with the flat surface 2a of the positioning table 2, and the sample 14 The surface is brought into close contact with the radiation surface 11b (second contact step). In this second contact step, an underlay 16 is further placed on the conductive substrate 15 for the hole 11a of the upper lid 11 of the probe resonator 3, that is, the portion overlapping the radiation position of the near-field electromagnetic wave, A weight 17 is placed on the underlay 16. By laying the underlay 16 in this manner, it is possible to apply a load by the weight 17 while suppressing distortion of the sample 14, so that the lower surface of the sample 14 can be more closely attached to the radiation surface 11b. The underlay 16 is not limited to the plate-like one shown in FIG. 3 on the condition that it has a smooth surface and a hardness that does not cause distortion, and a block-like one can also be adopted. Specifically, a ceramic gauge block can be employed as the underlay 16.

  Next, high-frequency power is supplied from the oscillator 4 (see FIG. 1) to the probe resonator 3 to radiate near-field electromagnetic waves from the radiation surface 11b of the probe resonator 3 (radiation process). Specifically, a resonance phenomenon occurs in the probe resonator 3 due to the supply of high-frequency power, but the size of the hole 11a of the probe resonator 3 is extremely small with respect to the wavelength of the resonating electromagnetic wave. Therefore, the electromagnetic wave cannot pass through the hole 11a, and a so-called near-field electromagnetic wave is generated in which the electric field slightly leaks through the hole 11a and stops there.

  Next, the resonance frequency of the near-field electromagnetic wave is detected by the analyzer 5 (see FIG. 1) (this detection step). This is because the resonance frequency of the near-field electromagnetic wave varies depending on the dielectric constant of the sample 14 that is in close contact with the probe resonator 3, and therefore the dielectric constant of the sample 14 can be measured based on this resonance frequency.

  In the present embodiment, the sample 14 is in close contact with the upper lid body 11 and the conductive substrate 15 of the probe resonator 3 having conductivity before the detection step, that is, the sample 14 is the upper lid body. 11 and the conductive substrate 15. Therefore, in this embodiment, compared with the case where only the sample 14 is brought into close contact with the probe resonator 3, the detection value (signal strength) of the resonance frequency can be increased. The reason is as follows.

  Specifically, the resonance frequency f of the near-field electromagnetic wave is proportional to the capacitance (capacitance) of the probe resonator 3 as shown in the following formula (1).

f = 2π × L × (C + Ct) × K (1)
Here, L is the inductance of the probe resonator 3, and K is a proportionality constant. Further, C is the capacitance of the probe resonator 3 that varies as the near-field electromagnetic wave penetrates into the sample 14 that is in close contact with the probe resonator 3. Ct is a capacitance that is apparently added as a capacitance of the probe resonator 3 by being sandwiched between the conductive substrate 15 and the probe resonator 3, and a member (conductive substrate) that sandwiches the sample 14 with the probe resonator 3. The larger the conductivity of 15), the larger the value obtained. That is, the capacitance Ct becomes 0 when the conductive substrate 15 does not exist (only the sample 14 is brought into close contact with the probe resonator 3). Therefore, the sample 14 is sandwiched between the probe resonator 3 and the conductive substrate 15 as compared with the resonance frequency [2π × L × C × K] obtained when only the sample 14 is brought into close contact with the probe resonator 3. In this case, the resonance frequency [2π × L × (C + Ct) × K] obtained is increased by the apparent capacitance Ct. In addition, the detected value of the resonance frequency increases as the conductivity of the substrate (conductive substrate 15 in the present embodiment) in close contact with the sample 14 increases. This point will be described below with reference to FIGS.

FIG. 5 is a graph showing the relationship between the dielectric constant of the sample 14 and the shift of the resonance frequency, and shows a case where a silicon substrate (without dopant) is employed as the substrate that is in close contact with the sample 14. FIG. 6 is a graph showing the relationship between the dielectric constant of the sample 14 and the shift of the resonance frequency, and shows a case where an aluminum substrate is employed as the conductive substrate 15. 5 and 6 were measured on a specimen in which a 1 μm thin film of the sample 14 made of the same material was formed on the substrate. The conductivity [37.7 × 10 ⁶ (m ⁻¹ × Ω ⁻¹ )] of the aluminum substrate is the conductivity [2.52 × 10 ⁻⁴ (m ⁻¹ × Ω ⁻¹ ) of the silicon substrate (no dopant). ], The resonance frequency of the aluminum substrate of FIG. 6 is one digit or more larger than the resonance frequency of the silicon substrate (without dopant) of FIG. It becomes. Specifically, when the resonance frequency in the vicinity of the dielectric constant 2 is compared, FIG. 6 is about 12 MHz and FIG. 5 is about 400 kHz (0.4 MHz), so the detected value of the resonance frequency is about 30 times. .

  Furthermore, since the apparent capacitance Ct increases as the sample 14 becomes thinner, the value of the resonance frequency increases as the sample 14 becomes thinner. Specifically, the apparent capacitance Ct is inversely proportional to the thickness dimension of the sample 14 as shown in the following formula (2).

Ct = σ × A ÷ T (2)
Here, σ is a dielectric constant, A is an opposing area between the probe resonator 3 and the conductive substrate 15, and T is a thickness dimension of the sample 14. Since the apparent capacitance Ct is inversely proportional to the thickness dimension of the sample 14 as described above, the detection value (detection signal) of the resonance frequency increases as the sample 14 becomes thinner, and the resolution of the dielectric constant improves. Therefore, for example, it is possible to effectively measure the dielectric constant of a thin film such as a high-k film used as a gate insulating film of a transistor.

  Then, the dielectric constant of the sample 14 is specified based on the resonance frequency detected in the main detection step and data prepared in advance as data indicating the relationship between the dielectric constant and the resonance frequency (data in FIG. 6). (Specific process). That is, prior to the specific step, the resonance frequency is detected in advance by the above-described method for the specimen in which the sample 14 having a known dielectric constant is formed on the conductive substrate 15 (preliminary detection step), and this data Based on (data in FIG. 6), the resonance frequency corresponding to the resonance frequency detected in the present detection step is specified.

  As described above, according to the present embodiment, since the near field electromagnetic wave is radiated in a state where the sample 14 is sandwiched between the conductive substrate 15 and the radiation surface 11b of the probe resonator 3, the near field electromagnetic wave The detected value of the resonance frequency can be increased. Specifically, the resonance frequency of the near-field electromagnetic wave is a value proportional to the capacitance of the probe resonator 3 that fluctuates according to the dielectric constant of the closely contacted sample 14, but the sample 14 is electrically conductive as in this embodiment. By arranging between the conductive substrate 15 and the probe resonator 3, the capacitance Ct between the conductive substrate 15 and the probe resonator 3 is also added as a part of the capacitance of the probe resonator 3. . That is, in this embodiment, since the capacitance Ct is apparently added to the capacitance C as a part of the capacitance of the probe resonator that determines the resonance frequency, the value of the resonance frequency of the near-field electromagnetic wave can be increased by the amount of the capacitance Ct. it can.

  Therefore, according to the present embodiment, the dielectric constant of the sample 14 can be measured with high accuracy by increasing the value of the resonance frequency of the near-field electromagnetic wave.

  If the thin film of the sample 14 is formed on the conductive substrate 15 as the first adhesion process (formation process) as in the embodiment, the dielectric constant of the thin film formed on the conductive substrate 15 is measured. Can do. In the first embodiment, the thin film of the sample 14 is formed on the conductive substrate 15 in the first adhesion process. However, the present invention is not limited to this, and in the first adhesion process, at least the conductive substrate 15 and the sample 14 are formed. Can be brought into close contact with each other.

  As in the above-described embodiment, the lower surface of the sample 14 is brought into close contact with the flat surface 2a of the positioning table 2 attached so as to be positioned on the same plane as the radiation surface 11b in the second contact step (formation step). Then, even if the sample 14 is larger than the radiating surface 11b, the portion of the sample 14 that protrudes outside the radiating surface 11b is positioned in close contact with the flat surface 2a, and the measurement target is in close contact with the radiating surface 11b. Can be made.

  If a predetermined load is applied to the conductive substrate 15 in the second contact step (formation step) as in the above embodiment, the sample 14 larger than the radiation surface is brought into close contact with the probe resonator 3. Even if it exists, it can suppress that the part which overlaps with the hole 11a of the probe resonator 3 among the samples 14 floats from the radiation | emission surface 11b. Therefore, according to this method, it is possible to improve the measurement accuracy of the resonance frequency by ensuring the close contact between the sample 14 and the radiation surface 11b while facilitating the close work of the large sample 14.

  In this embodiment, an underlay 16 and a weight 17 are placed to apply a load to the conductive substrate 15, but as shown in FIG. 4, a head 18 that can move up and down with respect to the probe resonator 3 is provided. A press machine (load adding means) may be provided, and the load may be applied to the conductive substrate 15 by lowering the head 18. In this case, the press machine is preferably configured to be controllable by the control device 6.

  If the sample 14 is brought into close contact with the radiation surface 11b and the flat surface 2a arranged upward in the second adhesion step (formation step) as in the above-described embodiment, the radiation surface 11b and the flat surface arranged upward are arranged. With the sample 14 placed on the surface 2a, it is possible to easily align the measurement target portion of the sample 14 with the radiation position of the near-field electromagnetic wave.

  As in the embodiment, specifying the dielectric constant of the sample 14 based on the resonance frequency detected in advance for the sample having a known dielectric constant in the preliminary detection step and the resonance frequency detected in the main detection step; In this case, the accuracy of dielectric constant measurement can be further improved by detecting the resonance frequency in advance for a large number of samples having different dielectric constants in the preliminary detection step.

The probe resonance is applied to the subject 1 that employs an aluminum substrate (mirror finish) as the conductive substrate 15 and an SiO ₂ thin film (relative dielectric constant of about 3) formed on the aluminum substrate as the sample 14. The vessel 3 was brought into close contact with the resonance frequency. Incidentally, the SiO ₂ thin film having a thickness is 11508 × ^{10 -10} m.

Further, the resonance frequency was detected by bringing the probe resonator 3 into close contact with the comparative sample 2 which is an aluminum substrate (mirror finish) on which the SiO ₂ thin film is not formed.

  As a result of measuring seven times for each of the subject 1 and the comparative sample 2 by the probe resonator 3 to which power of 790 MHz was applied, the resonance frequency of the subject 1 is lower than the resonance frequency of the comparative sample 2 by an average of 447 kHz. became.

Originally, the greater the distance between the probe resonator 3 and the aluminum substrate, the greater the resonance frequency should be. In the first embodiment, the greater the distance between the probe resonator 3 and the aluminum substrate. The resonance frequency decreases as the thickness of the SiO ₂ thin film increases. From this result, it was confirmed that the resonance frequency shifted according to the dielectric constant of the SiO ₂ thin film.

As the conductive substrate 15, a silicon wafer having a resistance value of 10 Ω × cm is employed, and the probe resonator 3 is used for the subject 3 employing a SiO ₂ thin film formed by CVD on the silicon wafer as the sample 14. Was closely attached to measure the resonance frequency.

Further, the resonance frequency was detected by bringing the probe resonator 3 into close contact with the comparative specimen 4 which is an aluminum substrate (mirror finish) on which the SiO ₂ thin film is not formed.

  As a result of measuring seven times for each of the subject 3 and the comparative sample 4 with the probe resonator 3 to which 790 MHz power was applied, the following results 1 to 3 were obtained.

<Result 1>
The resonance frequency of the subject 3 having a SiO ₂ thin film of 2893 × 10 ⁻¹⁰ m was lower than the comparative sample 4 on average by 680 kHz.

<Result 2>
The resonance frequency of the subject 3 having a SiO ₂ thin film of 10739 × 10 ⁻¹⁰ m was lower than that of the comparative sample 4 by an average of 1500 kHz.

<Result 3>
The resonance frequency of the subject 3 having the SiO ₂ thin film of 13518 × 10 ⁻¹⁰ m was 1720 kHz lower than the comparative sample 4 on average.

Originally, when the thickness of the SiO ₂ thin film increases, the probe resonator 3 should shift from the aluminum substrate to increase the resonance frequency (return to open air). It shifts in the direction of lowering. From these results 1 to 3, it was confirmed that the resonance frequency shifted according to the dielectric constant of the SiO ₂ thin film.

DESCRIPTION OF SYMBOLS 1 Measuring apparatus 2 Positioning table 2a Flat surface 3 Probe resonator 5 Analyzer 7 Outer conductor 8 Inner conductor 14 Sample 15 Conductive substrate 16 Underlay 17 Weight 18 Head

Claims (8)

A method for measuring the dielectric constant of a sample using a probe resonator having a radiation surface capable of emitting near-field electromagnetic waves,
A conductive member having higher conductivity than the sample and the radiation surface of the probe resonator are brought into close contact with the sample from a direction opposite to each other, whereby the conductive member and the probe resonator are interposed between each other. Forming step of forming capacitance;
A radiation step of radiating near-field electromagnetic waves from the radiation surface of the probe resonator in the state of performing the formation step;
A main detection step of detecting a resonance frequency of the near-field electromagnetic wave while performing the radiation step;
And a specifying step of specifying the dielectric constant of the sample based on the resonance frequency detected by the main detection step.   2. The dielectric constant according to claim 1, wherein in the forming step, the conductive substrate and the sample are brought into close contact with each other by forming a thin film of the sample on a conductive substrate as the conductive member. Measuring method. The radiation surface of the probe resonator and the contact surface of the sample that is in close contact with the radiation surface are flat surfaces, respectively.
A positioning member having a flat surface disposed so as to be located on the same plane as the radiation surface of the probe resonator is provided;
In the forming step, the sample and the probe resonator are positioned by bringing the contact surface of the sample into close contact with the radiation surface while positioning the contact surface of the sample with the flat surface of the positioning member. The method of measuring a dielectric constant according to claim 1 or 2, wherein: On the radiation surface of the probe resonator, a radiation position for radiating the near-field electromagnetic wave is set in advance,
The dielectric constant measurement according to claim 3, wherein in the forming step, a predetermined load toward the probe resonator is applied to at least a part of the conductive member including a portion overlapping the radiation position. Method. The radiation surface and the flat surface of the probe resonator are respectively arranged upward,
In the forming step, the contact surface is brought into close contact with the radiation surface while the sample with the contact surface facing downward is placed on the radiation surface and the flat surface arranged upward. The dielectric constant measuring method according to claim 3 or 4. Further comprising a preliminary detection step of detecting a resonance frequency for a sample having a known dielectric constant;
The unknown dielectric constant is specified in the specifying step by comparing the resonance frequency detected in the preliminary detection step with the resonance frequency detected in the main detection step. The dielectric constant measuring method according to any one of? An apparatus for measuring a dielectric constant of a sample,
A probe resonator having a radiation surface capable of emitting near-field electromagnetic waves;
A positioning member having a flat surface disposed on the same plane as the radiation surface of the probe resonator,
The radiation surface of the probe resonator is a flat surface,
2. The dielectric constant measuring apparatus according to claim 1, wherein the probe resonator and the positioning member are disposed such that the radiation surface and the flat surface are directed upward.   The load adding means which provides the predetermined load which is provided in the said base and is mounted on the said radiation | emission surface and goes to the said radiation | emission surface side is further provided. Dielectric constant measuring device.

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