JP4805752B2 - Dielectric constant measuring device - Google Patents

Description

  The present invention relates to a dielectric constant measuring apparatus for measuring a dielectric constant or a nonlinear dielectric constant of a dielectric sample.

  As a dielectric constant measuring apparatus for measuring the dielectric constant of a dielectric sample, a scanning nonlinear dielectric microscope (SNDM) has been developed (Non-patent Document 1). The operating principle of this microscope is that when the probe is brought into contact with the dielectric sample, the capacitance changes in accordance with the dielectric constant of the dielectric sample immediately below the probe, so that the LC oscillation circuit connected to the probe is This is a mechanism for measuring the dielectric constant by measuring the oscillation frequency.

  However, the capacitance generated according to the dielectric constant of the dielectric sample when the probe is brought into contact with the dielectric sample also depends on the force (contact force) pressing the probe against the dielectric sample. Therefore, in order to quantitatively measure the dielectric constant, it is required to keep the contact force of the probe constant. However, for example, when measuring the location dependence of the dielectric constant, the contact force generally changes when the measurement location is changed due to uneven thickness of the dielectric sample or the sample stage not being completely horizontal. . Similarly, when measuring the temperature dependence of the dielectric constant, the temperature of the dielectric sample and the sample stage also changes, so that the contact force generally changes due to the thermal expansion and contraction of the dielectric sample and the sample stage.

  A probe called a cantilever is widely used in a scanning microscope as a means for keeping the contact force that changes slightly like this constant. The cantilever has a shape in which a probe is attached to the tip of a beam-like dielectric. Since the beam-like portion has a structure that bends and the bending condition and the contact force correspond to each other, the contact force can be kept constant by monitoring the bending condition to be constant. A method of monitoring the degree of bending can be achieved by applying light to the back surface of the beam-like portion and monitoring the reflected light.

In Non-Patent Document 2, an AC electric field is applied to a dielectric sample to measure the time-varying oscillation frequency of the LC oscillation circuit, and synchronous detection is performed with a lock-in amplifier at an integer multiple of the frequency of the AC electric field. Describes a method for measuring the nonlinear dielectric constant of a dielectric sample directly under the probe.
Yasuo Cho et al., "Quantitative Measurement of Linear and Nonlinear Dielectric Characteristics Using Scanning Nonlinear Dielectric Microscopy", Jpn.J.Appl.Phys.Vol.39 (2000) pp.3086-3089 Nagayasu et al., “Microscope for Nonlinear Dielectric Constant Distribution Measurement”, IEICE Transactions CI Vol.J78-CI, No.11, pp.593-598 (1995)

  When a conventional cantilever is used, the beam-shaped portion and the dielectric sample are very close to each other, and the area of the beam-shaped portion is overwhelmingly larger than the contact area of the probe with the dielectric sample. There is a problem that the capacitance between the electrode and the dielectric sample becomes large, and the capacitance information directly under the probe is hidden. Therefore, in order to accurately measure the dielectric constant of a dielectric sample whose dielectric constant varies spatially, an arithmetic processing after the measurement is indispensable.

  According to the present invention, the contact force of the probe with respect to the dielectric sample is always kept constant, and the spatial distribution of the dielectric constant and the temperature dependence can be accurately measured without performing post-measurement processing. An object of the present invention is to provide a dielectric constant measuring apparatus.

The first invention is connected to a sample stage on which a dielectric sample is placed, a probe brought into contact with the surface of the dielectric sample placed on the sample stage, an electrode having a fixed potential provided around the probe, and an oscillator The probe and the electrode are arranged in parallel with the capacitor so that the capacitance of the minute region immediately below the probe of the dielectric sample generated when the probe contacts the surface of the dielectric sample. An LC oscillation circuit to be connected; and a frequency discriminator connected to the LC oscillation circuit and measuring a frequency (oscillation frequency) of a signal output from the LC oscillation circuit, and a probe is brought into contact with the surface of the dielectric sample; In a dielectric constant measuring apparatus that measures the dielectric constant of a minute region immediately below a probe tip of a dielectric sample from the oscillation frequency of the LC oscillator circuit measured by a frequency discriminator, the probe is electrically connected to the LC oscillator circuit. The central conductor is inserted into the cylinder of the hollow cylindrical conductor, the center conductor is movable within the hollow cylindrical conductor, and has a stopper for preventing the hollow cylindrical conductor from falling off. Hold the hollow cylindrical conductor so that is in the vertical direction, attach the tip of the center conductor to the dielectric sample, and attach it to at least one of the probe holder and the sample stage. Between the sample stage and the probe a height adjustment mechanism for adjusting the height of at least attached to one of the probe holder and the sample stage, and a position adjusting mechanism for controlling the relative horizontal position of the probe and the dielectric sample, height adjustment mechanism The position of the dielectric sample that contacts the probe is changed by controlling the position adjustment mechanism, and the contact force of the probe to the surface of the dielectric sample is kept constant, and the dielectric constant of the dielectric sample is measured. Configuration Ru Der.

The second invention is connected to a sample stage on which a dielectric sample is placed, a probe to be brought into contact with the surface of the dielectric sample placed on the sample stage, an electrode having a fixed potential provided around the probe, and an oscillator The probe and the electrode are arranged in parallel with the capacitor so that the capacitance of the minute region immediately below the probe of the dielectric sample generated when the probe contacts the surface of the dielectric sample. LC oscillator circuit to be connected, a frequency discriminator for measuring the frequency (oscillation frequency) of the signal output from the LC oscillator circuit, connected to the LC oscillator circuit, connected to the sample stage and the electrode, and having a predetermined frequency on the sample stage An AC signal generator for applying an AC electric field, a frequency discriminator and a lock-in amplifier connected to the AC signal generator, a probe is brought into contact with the surface of the dielectric sample, and the frequency The signal of the oscillation frequency of the LC oscillation circuit measured by a separate device is input to the lock-in amplifier, and synchronous detection is performed at a frequency that is an integral multiple of the frequency of the AC electric field applied by the AC signal generator, immediately below the probe of the dielectric sample. In the dielectric constant measuring apparatus for measuring the nonlinear dielectric constant of the micro region, the probe inserts the central conductor into the hollow cylindrical conductor electrically connected to the LC oscillation circuit, and the central conductor is the hollow cylindrical conductor. It has a stopper that is movable inside the cylinder and does not fall out of the hollow cylindrical conductor, holds the hollow cylindrical conductor so that the cylindrical central axis of the hollow cylindrical conductor is in the vertical direction, and the tip of the central conductor is a dielectric. A probe holder that is brought into contact with the sample, a height adjustment mechanism that is attached to at least one of the probe holder and the sample stage, and that adjusts the height between the sample stage and the probe; At least attached to one over di-, the probe and a position adjusting mechanism for controlling the relative horizontal position of the dielectric sample, dielectric sample probe by controlling the position adjusting mechanism and the height adjusting mechanism contacts while changing the position, kept constant the contact force of the probe to the surface of the dielectric sample, Ru configuration der to measure the dielectric constant of the dielectric sample.

Here, the probe may be configured to use a hollow cylindrical insulator in which a conductor material is attached to an outer wall surface electrically connected to the LC oscillation circuit, instead of the hollow cylindrical conductor. The sample stage may include a temperature control mechanism that controls the temperature of the dielectric sample.

  In the dielectric constant measuring apparatus of the present invention, the probe is composed of a hollow cylindrical conductor (or a hollow cylindrical insulator) and a central conductor, so that the contact force to the dielectric sample can be kept constant by the weight of the probe. Therefore, quantitative measurement of the dielectric constant or nonlinear dielectric constant of the dielectric sample can be easily performed. Further, since a monitoring mechanism for keeping the contact force of the probe constant like a conventional cantilever is not required, a simple and inexpensive dielectric constant measuring apparatus can be realized.

(First embodiment)
FIG. 1 shows a first embodiment of the dielectric constant measuring apparatus of the present invention. In FIG. 1A, a probe 101 is configured to come into contact with the surface of a dielectric sample 109 placed on a sample stage 108, and an electrode 102 having a fixed potential (here, ground potential) around the probe 101. Is provided. When the probe 101 comes into contact with the surface of the dielectric sample 109, a capacitance Cs is generated in a minute region of the dielectric sample 109 immediately below the probe 101. The LC oscillation circuit 106 includes a capacitor (capacitance C ₀ ) 103 and an inductor (inductance L) 104 connected to the oscillator 105, and a capacitance Cs generated when the probe 101 contacts the dielectric sample 109 is parallel to the capacitor 103. The LC oscillation circuit 106, the probe 101, and the electrode 102 are connected so that A frequency discriminator 107 is connected to the LC oscillation circuit 106, and the frequency (oscillation frequency) of the signal output from the LC oscillation circuit 106 is measured.

FIG. 1B shows an equivalent circuit around the LC oscillation circuit 106 when the probe 101 contacts the dielectric sample 109. The oscillation frequency fs of the LC oscillation circuit 106 when the probe 101 contacts the dielectric sample 109 is expressed by the following equation (Non-patent Document 1).
fs = 1 / [2π (L (C ₀ + Cs)) ^1/2 ] (1)

  Due to such a relationship, the oscillation frequency fs changes when the capacitance Cs of the minute region of the dielectric sample 109 immediately below the probe 101 changes. Therefore, the frequency discriminator 107 measures the oscillation frequency fs to thereby determine the capacitance Cs. The dielectric constant corresponding to can be measured. The above is the basic configuration in the category of the prior art. The feature of the present invention is the structure of the probe 101 in which the contact force of the probe 101 with respect to the dielectric sample 109 is always constant. An example of the configuration will be shown.

  FIG. 2 shows a first configuration example of the probe 101. In FIG. 2A, the probe 101 has a structure in which a center conductor 202 is inserted into a cylinder of a hollow cylindrical conductor 201. The hollow cylindrical conductor 201 is electrically connected to the LC oscillation circuit 106, and the hollow cylindrical conductor 201 and the center conductor 202 are electrically connected by physical contact. The hollow cylindrical conductor 201 is held by a probe holder (not shown) so that the cylindrical central axis is in the vertical direction, and the central conductor 202 is movable in the cylinder of the hollow cylindrical conductor 201, but at one end so as not to fall off. A stopper 203 is attached. The center conductor 202 is configured to protrude from the lower end of the hollow cylindrical conductor 201 at a position where the central conductor 202 is stopped by the stopper 203. That is, the center conductor 202 is movable by the length of the protrusion.

  The state of the probe 101 when the tip of the central conductor 202 is not touching anything is shown in FIG. The center conductor 202 is caught by the hollow cylindrical conductor 201 by the stopper 203 and does not fall off. Here, FIG. 2 (c) shows a state in which the center conductor 202 of the probe 101 and the dielectric sample 109 are brought closer to each other and the center conductor 202 and the dielectric sample 109 are brought closer to each other from the contact state. The relationship between the center conductor 202 and the dielectric sample 109 may be that the probe holder that holds the hollow cylindrical conductor 201 may be lowered, or the sample stage (FIG. 1: 108) on which the dielectric sample 109 is placed is moved upward. You may make it lift. At this time, the center conductor 202 is pushed up and lifted by the dielectric sample 109 from below, but electrical connection is maintained by contact between the side surface of the center conductor 202 and the inner wall surface of the hollow cylindrical conductor 201.

  When the mass of the central conductor 202 is m, the gravity acting on the central conductor 202 is mg (g is gravitational acceleration). If the frictional force due to the contact between the side surface of the center conductor 202 and the inner wall surface of the hollow cylindrical conductor 201 is sufficiently smaller than mg, the force that the center conductor 202 presses the dielectric sample 109 (the probe 101 and the dielectric sample 109 Frictional force is negligible for (contact force). That is, the contact force between the probe 101 and the dielectric sample 109 is always mg and is constant.

Therefore, by using the probe 101 composed of the hollow cylindrical conductor 201 and the center conductor 202, it is possible to always realize a constant contact force. Further, even if the relative position between the hollow cylindrical conductor 201 and the central conductor 202 slightly moves up and down, the distance between the probe holder that holds the hollow cylindrical conductor 201 and the dielectric sample 109 is sufficiently large. The total capacitance (C ₀ + Cs) including the capacitance Cs in the sample 109 hardly changes.

  Accordingly, since the capacitance Cs when the dielectric constant of the dielectric sample 109 immediately below the probe 101 (center conductor 202) has a certain value is uniquely determined, the oscillation frequency fs and the dielectric constant are 1 according to the equation (1). As a result, it is possible to perform quantitative measurement of permittivity with reproducibility.

  That is, by using a reference sample whose dielectric constant value is known in advance, the relationship between the oscillation frequency and the dielectric constant is obtained, so that the dielectric is obtained from the oscillation frequency fs measured by the frequency discriminator (FIG. 1: 107). The dielectric constant of the sample 109 can be obtained. Further, since a monitor mechanism for keeping the contact force of the probe 101 constant like a conventional cantilever is not required, a simple and inexpensive dielectric constant measuring apparatus can be realized.

FIG. 3 shows a second configuration example of the probe 101. In FIG. 3A, the probe 101 has a structure in which a center conductor 202 is inserted into a cylinder of a hollow cylindrical insulator 301. A conductive substance (metal film or the like) is attached to the outer wall surface of the hollow cylindrical insulator 301 and is electrically connected to the LC oscillation circuit 106, while a cylindrical capacitance C _pipe is connected to the central conductor 202. It is formed. The hollow cylindrical insulator 301 is held by a probe holder (not shown), and the center conductor 202 moves in the cylinder of the hollow cylindrical insulator 301, but a stopper 203 is attached to one end so as not to fall off. Other shapes are the same as those in the first configuration example.

FIG. 3B shows an equivalent circuit around the LC oscillation circuit 106 when the probe 101 having this configuration is brought into contact with the dielectric sample 109. Since the capacitance C _pipe in the hollow cylindrical insulator 301 is connected in series with the capacitance Cs of the dielectric sample 109, the oscillation frequency fs of the LC oscillation circuit 106 when the probe 101 contacts the dielectric sample 109. Is as follows.
fs = 1 / [2π (L (C ₀ + CsC _pipe / (Cs + C _pipe ))) ^1/2 ] (2)

In addition, since the position of the center conductor 202 is changed in accordance with the change in the height of the surface of the dielectric sample 109 by using the probe 101 composed of the hollow cylindrical insulator 301 and the center conductor 202, it is always constant. The contact force can be realized as in the first configuration example. Further, even if the relative position between the hollow cylindrical insulator 301 and the center conductor 202 is slightly moved up and down, the capacitance C _pipe in the hollow cylindrical insulator 301 hardly changes, and the probe holding the hollow cylindrical insulator 301 further. The distance between the holder and the dielectric sample 109 is sufficiently large, and the total capacitance C ₀ + CsC _pipe / (Cs + C _pipe ) including the capacitance Cs in the dielectric sample 109.
Is almost unchanged.

  Accordingly, since the capacitance Cs when the dielectric constant of the dielectric sample 109 immediately below the probe 101 (center conductor 202) has a certain value is uniquely determined, the oscillation frequency fs and the dielectric constant are 1 according to the equation (2). As a result, it is possible to perform quantitative measurement of permittivity with reproducibility.

(Second Embodiment)
FIG. 4 shows a second embodiment of the dielectric constant measuring apparatus of the present invention. In FIG. 4, the dielectric constant measuring apparatus of the present embodiment connects an AC signal generator 401 between the sample stage 108 and the electrode 102 in the configuration of the first embodiment shown in FIG. An AC electric field is applied, and a lock-in amplifier 402 is connected to the frequency discriminator 107 and the AC signal generator 401. The frequency discriminator 107 measures the time-varying oscillation frequency of the LC oscillation circuit 106, and the lock-in amplifier 402 performs synchronous detection at a frequency that is an integral multiple of the frequency of the AC electric field applied by the AC signal generator 401. The nonlinear dielectric constant of a minute region of the dielectric sample 109 immediately below 101 (center conductor 202) is measured.

An AC electric field E _p applied to the dielectric sample 109 by the AC signal generator 401 is expressed by the following equation, assuming a constant E ₀ , a frequency ω _p , and a time t.
E _p = E ₀ cos (ω _p t) (3)

At this time, the minute amount Δε in which the dielectric constant of the dielectric sample 109 changes with time has the following relationship (Non-Patent Document 2).
Δε = (1/4) ε (4) E ₀ ² + ε (3) E ₀ cos (ω _p t) + (1/4) ε (4) E ₀ ² cos (2ω _p t) + (4)
Here, ε (3), ε (4),... Are expansion coefficients when the electric flux density D is expanded by the electric field E as shown in the following equation.
D = P + ε (2) E + (1/2) ε (3) E ² + (1/6) ε (4) E ³ + (1/24) ε (5) E ⁴ + ... (5)

As the dielectric constant changes with time, the capacitance also changes with time. However, since the contact force is kept constant as in the first embodiment, the time change of the dielectric constant and the time change of the capacitance are 1: 1. Correspond. Therefore, the time change of the dielectric constant and the time change of the oscillation frequency shown in the equation (4) correspond one-to-one. That is, the time change of the oscillation frequency measured by the frequency discriminator 107 is an overlap of the DC component, the ω _p component, the 2ω _p component,.

Here, by performing synchronous detection using the lock-in amplifier 402, the coefficient of each term of the equation (4) can be extracted. For example, Motomari is ε (3) E ₀ by extracting the coefficients of _{cos (ω p t), cos} ε (4) by extracting the coefficients of ^{_{(2ω p t) E 0 2}} /4 is obtained. Therefore, if E ₀ is known, ε (3), ε (4),... Can be quantitatively measured.

  That is, by using a reference sample whose nonlinear dielectric constant is known in advance, the relationship between the oscillation frequency and the nonlinear dielectric constant is obtained, so that the dielectric sample 109 is obtained from the oscillation frequency fs measured by the frequency discriminator 107. A nonlinear dielectric constant can be obtained. Further, since a monitoring mechanism for keeping the contact force of the probe 101 constant like a conventional cantilever is not required, a simple and inexpensive nonlinear dielectric constant measuring apparatus can be realized.

(Third embodiment)
FIG. 5 shows a third embodiment of the dielectric constant measuring apparatus of the present invention. This embodiment shows an example of a temperature control mechanism used for temperature control of the dielectric sample 109 placed on the sample stage 108.

  In FIG. 5, a sample stage 108 is formed by disposing a Peltier element 502 and a heat bath 503 under the sample stage main body 501. When the temperature of the sample stage 108 is changed, the relative height between the probe 101 and the surface of the dielectric sample 109 arranged on the sample stage 108 generally changes due to thermal expansion / contraction. However, as described in the first embodiment, the probe 101 is composed of the hollow cylindrical conductor 201 (or the hollow cylindrical insulator 301) and the central conductor 202, so that the central conductor 202 is on the surface of the dielectric sample 109. The position changes according to the change in height, and the contact force can be made constant.

  Therefore, by using the sample stage 108 of the present embodiment, the temperature dependence of the dielectric constant and nonlinear dielectric constant of the dielectric sample 109 can be quantitatively measured. In particular, when a ferroelectric is used as the dielectric sample 109, the dielectric constant is maximized at the phase transition temperature at which the paraelectric-ferroelectric phase transition occurs. Therefore, by measuring the temperature dependence of the dielectric constant, It is possible to determine the transition temperature.

(Fourth embodiment)
FIG. 6 shows a fourth embodiment of the dielectric constant measuring apparatus of the present invention. In the present embodiment, a height adjustment mechanism used for height adjustment between the dielectric sample 109 and the probe 101, and a position control mechanism used for relative position control between the dielectric sample 109 and the probe 101. An example is shown.

  In the configuration shown in FIG. 6A, the probe holder 601 that holds the hollow cylindrical conductor 201 or the hollow cylindrical insulator 301 of the probe 101 is attached to the height adjustment mechanism 602, and the height between the dielectric sample 109 and the probe holder 601 is increased. Adjustments are made. On the other hand, the sample stage 108 on which the dielectric sample 109 is mounted is attached to the position control mechanism 603, and moves the position of the sample stage 108 in a two-dimensional plane.

  In the configuration shown in FIG. 6B, the probe holder 601 that holds the hollow cylindrical conductor 201 or the hollow cylindrical insulator 301 of the probe 101 is attached to the height adjustment mechanism 602 via the position control mechanism 603, and the dielectric The position and height of the probe 101 in the two-dimensional plane with respect to the body sample 109 are adjusted.

  In the configuration shown in FIG. 6C, the probe holder 601 that holds the hollow cylindrical conductor 201 or the hollow cylindrical insulator 301 of the probe 101 is fixed at a predetermined position and height. On the other hand, the sample stage 108 on which the dielectric sample 109 is placed is attached to the height adjustment mechanism 602 and the position control mechanism 603, and the position and height of the dielectric sample 109 in the two-dimensional plane with respect to the probe 101 are adjusted.

  The height adjusting mechanism 602 can use a commercially available X stage vertically, and the position control mechanism 603 can use a commercially available XY stage. Moreover, you may comprise combining a manual thing for coarse movements, and an electric thing for fine movements, respectively.

  As described above, the sample stage 108 on which the probe 101 and the dielectric sample 109 are placed may move either in the height direction or in the horizontal direction. When the position of the dielectric sample 109 in contact with the probe 101 is changed, the relative height between the probe 101 and the surface of the dielectric sample 109 is generally due to the unevenness of the height of the dielectric sample 109, the inclination of the sample stage 108, or the like. Changes. However, as described in the first embodiment, the probe 101 is composed of the hollow cylindrical conductor 201 (or the hollow cylindrical insulator 301) and the central conductor 202, so that the central conductor 202 is on the surface of the dielectric sample 109. The position changes according to the change in height, and the contact force can be made constant.

  Therefore, by using the position control mechanism 603 of this embodiment, it is possible to quantitatively measure the position dependency of the dielectric constant and the nonlinear dielectric constant of the dielectric sample 109. In particular, when a ferroelectric is used as the dielectric sample 109, the location dependence of the phase transition temperature at which the paraelectric-ferroelectric phase transition occurs can be obtained by combining with the temperature control mechanism of the third embodiment. It becomes possible.

The figure which shows 1st Embodiment of the dielectric constant measuring apparatus of this invention. The figure which shows the 1st structural example of the probe 101. FIG. The figure which shows the 2nd structural example of the probe 101. FIG. The figure which shows 2nd Embodiment of the dielectric constant measuring apparatus of this invention. The figure which shows 3rd Embodiment of the dielectric constant measuring apparatus of this invention. The figure which shows 4th Embodiment of the dielectric constant measuring apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Probe 102 Electrode 103 Capacitor 104 Inductor 105 Oscillator 106 LC oscillation circuit 107 Frequency discriminator 108 Sample stage 109 Dielectric sample 201 Hollow cylindrical conductor 202 Central conductor 203 Stopper 301 Hollow cylindrical insulator 401 AC signal generator 402 Lock-in amplifier 501 Sample stage body 502 Peltier element 503 Heat bath 601 Probe holder 602 Height adjustment mechanism 603 Position control mechanism

Claims (4)

A sample stage on which a dielectric sample is placed;
A probe in contact with the surface of the dielectric sample placed on the sample stage;
An electrode having a fixed potential provided around the probe;
A capacitor and an inductor connected to an oscillator are provided so that a capacitance in a minute region immediately below the probe of the dielectric sample generated when the probe contacts the surface of the dielectric sample is in parallel with the capacitor. LC oscillation circuit connected to the probe and the electrode,
A frequency discriminator connected to the LC oscillation circuit and measuring a frequency (oscillation frequency) of a signal output from the LC oscillation circuit, the probe contacting the surface of the dielectric sample, and the frequency discriminator. In a dielectric constant measuring apparatus for measuring a dielectric constant of a minute region immediately below the probe of the dielectric sample from the oscillation frequency of the LC oscillation circuit measured in
The probe inserts a central conductor into a hollow cylindrical conductor cylinder electrically connected to the LC oscillation circuit, the central conductor is movable within the hollow cylindrical conductor cylinder, and does not fall out of the hollow cylindrical conductor. And having a stopper of
A probe holder for holding the hollow cylindrical conductor so that a cylindrical central axis of the hollow cylindrical conductor is in a vertical direction, and contacting a tip of the central conductor with the dielectric sample;
A height adjustment mechanism that is attached to at least one of the probe holder and the sample stage and adjusts the height between the sample stage and the probe;
A position adjusting mechanism that is attached to at least one of the probe holder and the sample stage and controls a relative position in a horizontal direction of the probe and the dielectric sample; and controls the height adjusting mechanism and the position adjusting mechanism. Then, while changing the position of the dielectric sample in contact with the probe, the contact force of the probe with respect to the surface of the dielectric sample is kept constant, and the dielectric constant of the dielectric sample is measured. A dielectric constant measuring apparatus. A sample stage on which a dielectric sample is placed;
A probe in contact with the surface of the dielectric sample placed on the sample stage;
An electrode having a fixed potential provided around the probe;
A capacitor and an inductor connected to an oscillator are provided so that a capacitance in a minute region immediately below the probe of the dielectric sample generated when the probe contacts the surface of the dielectric sample is in parallel with the capacitor. LC oscillation circuit connected to the probe and the electrode,
A frequency discriminator connected to the LC oscillation circuit and measuring a frequency (oscillation frequency) of a signal output from the LC oscillation circuit;
An AC signal generator connected to the sample stage and the electrode and applying an AC electric field having a predetermined frequency to the sample stage;
An oscillation frequency of the LC oscillation circuit measured by the frequency discriminator, comprising: the frequency discriminator; and a lock-in amplifier connected to the AC signal generator; the probe contacting the surface of the dielectric sample; Is input to the lock-in amplifier, and the nonlinear dielectric constant of a minute region immediately below the probe of the dielectric sample is obtained by synchronous detection at an integer multiple of the frequency of the AC electric field applied by the AC signal generator. In the dielectric constant measuring device to measure,
The probe inserts a central conductor into a hollow cylindrical conductor cylinder electrically connected to the LC oscillation circuit, the central conductor is movable within the hollow cylindrical conductor cylinder, and does not fall out of the hollow cylindrical conductor. And having a stopper of
A probe holder for holding the hollow cylindrical conductor so that a cylindrical central axis of the hollow cylindrical conductor is in a vertical direction, and contacting a tip of the central conductor with the dielectric sample;
A height adjustment mechanism that is attached to at least one of the probe holder and the sample stage and adjusts the height between the sample stage and the probe;
A position adjusting mechanism that is attached to at least one of the probe holder and the sample stage and controls a relative position in a horizontal direction of the probe and the dielectric sample; and controls the height adjusting mechanism and the position adjusting mechanism. Then, while changing the position of the dielectric sample in contact with the probe, the contact force of the probe with respect to the surface of the dielectric sample is kept constant, and the dielectric constant of the dielectric sample is measured. A dielectric constant measuring apparatus. In the dielectric constant measuring apparatus according to claim 1 or 2,
The probe has a configuration using a hollow cylindrical insulator in which a conductor material is attached to an outer wall surface electrically connected to the LC oscillation circuit, instead of the hollow cylindrical conductor. apparatus. In the dielectric constant measuring apparatus according to claim 1 or 2,
2. The dielectric constant measuring apparatus according to claim 1, wherein the sample stage includes a temperature control mechanism for controlling a temperature of the dielectric sample.

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