JPH07120421A - Thin film thermal diffusivity measuring device, method of manufacturing the same, and thermal diffusivity measuring method - Google Patents

Abstract

(57) [Summary] (Corrected) [Purpose] Highly accurate measurement of thermal diffusivity in the surface direction (direction perpendicular to the thickness) of various thin film samples with a thickness of about 1 μm using a relatively simple device. Provided is a thermal diffusivity measuring device capable of performing the above. A thin-film thermal diffusivity measuring apparatus 100 includes a substrate 10 having an external communication portion 12 opened upward and a substrate 10 formed on the substrate 10 and bridged on a part of the external communication portion 12. And a supporting film 20 made of an insulating thin film having a supporting portion 22 formed therein. On the support film 20, at least one end of the first conductive portion 32 is located in the support portion 22, and at least one end is located in the support portion 22, and the first conductive portion 32 is located. A second conductive portion 42 is formed at a predetermined distance from 32.
Further, on the supporting film 20, the measured film 60 having a bridge-shaped measured portion 62 is formed via the auxiliary supporting film 50.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring the thermal diffusivity of a thin film by periodic heating, a method for manufacturing the measuring apparatus and a method for measuring the thermal diffusivity using the measuring apparatus.

The thermal diffusivity measuring apparatus and measuring method of the present invention are suitable for measuring the thermophysical properties of thin films of about 1 μm. The measurement technology for the thermophysical properties of such thin films is
In recent years, its development has been desired for the following reasons.

(A) With high integration and high speed of IC,
The heat generated by the elements and wiring cannot be ignored from the viewpoint of IC malfunction and reliability.

(B) A technique for developing a physical property in a thin film that cannot be obtained by a bulk material, a method for obtaining a physical property value of a thin film of a material for which a bulk material is not obtained, or a thermal type using a thin film as a structure. Measurement of thermophysical properties of thin films is required in the device design, etc.

[0005]

2. Description of the Related Art There have been few reports on a technique for accurately measuring thermophysical property values of a thin film having a thickness of about 1 μm used in a semiconductor process. This is because it is very difficult to measure the thermophysical properties of such a thin film.

Techniques for measuring thermophysical properties of thin films include:
As disclosed in JP-A-60-155950,
There is a method of measuring thermal diffusivity by adiabatic heating. In this thermal diffusivity measurement method, one surface of a thin sample plate with a constant thickness is covered with a covering material, and one surface is intermittently irradiated with thermal energy of a constant amplitude to shield the sample plate to be measured. The AC temperature at various points from the end of the cover member in the section is measured, and the thermal diffusivity of the sample plate to be measured is calculated from the gradient of the AC temperature characteristic line with the distance as a variable and the AC frequency. is there.

[0007] This thermal diffusivity measuring method is, for example, a thickness of 0.
Although it is useful for measuring the thermal diffusivity of a film having a thickness of about 1 to 0.5 mm, the thickness is 1 μm for the following reasons.
It has a drawback that it cannot be applied to a thin film having a level of about m.

Since only the sample to be measured has a very small thickness, it has a small mechanical strength and cannot be used alone for measurement. In order to compensate for this point, it is possible to measure with the sample to be measured placed on the substrate. In this case, however, the thickness of the substrate is larger than that of the sample to be measured. Depends on the substrate, and an accurate measurement result of the sample to be measured cannot be obtained.

In the above technique, light irradiation is used as a heat source, but it is difficult to heat the sample to be measured because the transparent thin film transmits light and is not converted into heat.

The present invention solves the problems of the prior art as described above, and its object is to determine the thermal diffusivity in the plane direction (direction perpendicular to the thickness direction) in various thin film samples having a thickness of about 1 μm. An object of the present invention is to provide a thermal diffusivity measuring device capable of highly accurate measurement with a device having a relatively simple structure.

Another object of the present invention is to provide a method of manufacturing a thermal diffusivity measuring device, which can manufacture the thermal diffusivity measuring device with a simple process with high accuracy.

Still another object of the present invention is to provide a measuring method which can obtain a highly accurate thermal diffusivity by using the thermal diffusivity measuring device.

[0013]

SUMMARY OF THE INVENTION A thin film thermal diffusivity measuring apparatus of the present invention is a substrate having an external communication portion opened upward, and a part of the external communication portion formed on the substrate. A support film made of an insulating thin film, having a support part bridge-shaped, and a first conductive part formed on the support film, at least one end of which is located on the support part; A heating means having an AC power source electrically connected to the first conductive portion; and a heating means formed on the support film, at least one end of which is located on the support portion, and which has a predetermined distance from the first conductive portion. A temperature detecting means having a second conductive portion located at a distance and a resistance measuring portion electrically connected to the second conductive portion; and at least the support portion, the first conductive portion and the temperature detecting means. A block formed over the region including the second conductive portion. Characterized in that it comprises a measured film, a having Tsu-shaped part to be measured.

A single crystal silicon substrate is usually used as the substrate, and its thickness is about 300 to 600 μm.

The support film is made of a material which is insulative and has a mechanical strength sufficient to maintain the shape of a thin film. Examples of such a material include a silicon nitride film and a silicon oxide film. The thickness of the support film is preferably about the same as the film to be measured,
Usually, it is about 1000 to 5000 angstroms.

The conductive part is not particularly limited in material as long as it has sufficient conductivity to function as a heater or an electrode. For example, polysilicon is doped with impurities to have conductivity, or Ni is used. , Pt, Au, etc. can be used.

The thin film to be measured is selected from various thin films depending on the object to be measured. For example, SiO2, phosphorus glass (P
SG), aluminum, gold, gold black, lead zirconate titanate (PZT), lead germanate (PGO), polyvinylidene fluoride, polyimide, and other thin films.

The method of manufacturing the thermal diffusivity measuring device of the present invention is
A step of forming a supporting film made of an insulating thin film on a silicon substrate, and a patterning and etching by photolithography after forming a conductive film on the supporting film to form a first conductive portion that constitutes a heating unit. And a step of forming a second conductive portion which constitutes the temperature detecting means,
A step of forming a film to be measured so as to cover at least the region including the first conductive portion and the second conductive portion, and removing a part of the silicon substrate under the support film by anisotropic etching, Forming a bridge-shaped measurement region including the first conductive portion and the second conductive portion and forming an external communication portion.

According to this manufacturing method, the supporting film, the conductive portion, and the film to be measured can be formed by the thin film forming technique used for manufacturing an IC or the like. As a thin film forming method, a chemical vapor deposition method (CVD
Method), a physical vapor deposition method (PVD method) such as sputtering, ion plating, or the like.

The thermal diffusivity measuring method of the present invention is a thermal diffusivity measuring apparatus according to claim 1, wherein the distance L between the first conductive portion and the second conductive portion is different from each other. Using the device, the temperature amplitude Tac in each measuring device is measured, and the distance L and the temperature amplitude T obtained by the following equation 3 are calculated.
It is characterized in that the damping constant k is obtained from the correlation with ac, and the thermal diffusivity α is obtained from the following equation 4.

[Equation 3]

[Equation 4]

In the thermal diffusivity measuring apparatus of the present invention, the heating means is operated, that is, an AC voltage having a constant frequency is applied to the first conductive portion to periodically heat it (AC heating).
The temperature amplitude Tac can be measured as a resistance change by the resistance measuring section of the temperature detecting means via the second conductive section.

According to the thermal diffusivity measuring apparatus of the present invention, since the film to be measured is supported by the thin supporting film formed on the substrate, the measurement can be performed even with an extremely thin film of 1 μm level. It is possible. And, since the support film can have a thickness similar to that of the measurement film, for example,
The thermal diffusivity of the film to be measured can be measured with high accuracy by accurately considering the thermal diffusivity of the support film.

Further, since the first conductive portion functioning as a heater of the heating means is heated by resistance heating, heating necessary for measurement is performed even with a transparent thin film of about 1 μm, unlike the case of light irradiation. be able to. Further, since the second conductive portion constituting the temperature detecting means is provided directly to the film to be measured or via the insulating film (auxiliary supporting film), the emissivity can be measured even for the unknown sample. It can be performed.

Further, since the measuring device of the present invention is manufactured by a thin film forming process as will be described later, it has a small size, a high precision and a simple structure.
Therefore, there are few error factors, and highly accurate measurement can be performed. Further, since this device has a small size, there is an advantage that a large-scale device is not required even when the measurement is performed in a vacuum, for example.

According to the method of manufacturing the thermal diffusivity measuring apparatus of the present invention, a small and highly accurate apparatus can be easily manufactured by a thin film forming process such as the CVD method. Then, a large number of samples in a state before forming the film to be measured are prepared by batch processing at one time, and these are stored at all times, and only the thin film to be measured is formed on these samples at the time of measurement. Since it is possible to create various materials, it is easy to create a sample.

Further, according to the thermal diffusivity measuring method using the thermal diffusivity measuring device, the distance between the first conductive portion constituting the heating means and the second conductive portion constituting the temperature detecting means is different. By calculating the correlation between the distance L and the temperature amplitude Tac using two or more thermal diffusivity measuring devices, the thermal diffusivity of the film to be measured can be calculated with high accuracy.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view schematically showing the thermal diffusivity measuring apparatus of this embodiment. FIG. 4 (I) is a sectional view taken along the line I-I of the measuring apparatus shown in FIG.

The thermal diffusivity measuring apparatus 100 of this embodiment comprises a substrate 10, a support film 20 formed on the substrate 10,
The first conductive portion 32 and the second conductive portion 32 formed on the support film 20.
The conductive portion 42, the auxiliary support film 50 formed so as to cover these conductive portions 32, 42, and the film to be measured 60 formed on the auxiliary support film 50.

The substrate 10 is made of, for example, (100) plane single crystal silicon and has a thickness of about 300 to 600 μm. Further, an external communication portion 12 formed of a concave portion opened upward is formed in a substantially central portion of the substrate 10.

The support film 20 has a thickness of 1000 to 500.
It is composed of a silicon nitride film of 0 angstrom. Further, the support film 20 has a bridge-shaped support portion 22 which is bridged over substantially the center of the external communication portion 12. The longitudinal direction of the support portion 22 is formed in the <110> direction of the silicon substrate 10. The films on both sides of the support portion 22 are removed so as to be continuous with the external communication portion 12.

The first conductive portion 32 and the second conductive portion 42 are composed of a conductive film formed by doping a polysilicon film with impurities. The first conductive portion 3
2 functions as a heater of heating means by AC heating, and the second conductive portion 34 functions as an electrode of temperature detecting means. The distance L between the first conductive portion 32 and the second conductive portion 42 is set in advance to a value required for measurement.

The auxiliary supporting film 50 has a thickness of about 1000-.
It is composed of a 5000 angstrom silicon nitride film. This auxiliary supporting film 50 is not always necessary, but when it is necessary to improve the film forming property of the film to be measured to form a uniform film to be measured or to measure a conductive film to be measured. Is formed as a base layer.

The film to be measured 60 is various thin films to be measured, and in this example, the film thickness is from 1000 to 10
It is composed of a SiO ₂ film of 000 Å. The film 60 to be measured has a portion 62 to be measured at a position corresponding to the support portion 22 in the previous period.

In this embodiment, the support film 20,
The auxiliary supporting film 50 and the film to be measured 60 are the supporting parts 22
Also, the portions corresponding to the external communication portion 12 are removed on both sides of the measurement region 24 including the measured portion 62. Therefore, the measurement area 24 is in the shape of a three-layer bridge, and the periphery thereof is open.
Therefore, for example, by setting the measurement system in a vacuum state, it is possible to suppress unfavorable heat dissipation due to heat transfer from the measurement region.

The surface of the film 60 to be measured is shown in FIG.
As shown in FIG. 3, aluminum wiring films 70 and 72 electrically connected to the first conductive portion 32 and the second conductive portion 42 through the contact holes H are formed.

FIG. 2 is a schematic diagram showing the heating means 30 and the temperature detecting means 40 of the measuring apparatus 100 of FIG. As shown in the drawing, the heating means 30 is configured by electrically connecting the first conductive portion 32 and the AC power source 34 via a wiring film 70. In this heating means 30, by applying an AC voltage having a predetermined frequency to the first conductive portion 32 by the AC power source 34, the measured portion 62 of the measured film 60 is heated cyclically by resistance heating (AC heating). )can do. The first conductive portion 32, which functions as a heater, is connected to the film to be measured 60 without a space though the auxiliary support film 50 is interposed, so that the radiant heat of the film to be measured is considered. It is not necessary, and a predetermined amount of heat can be accurately applied to the film to be measured.

In the temperature detecting means 40, the second conductive portion 42 has a constant current power source 44 via a wiring film 72.
And a voltmeter 46 connected in parallel. Therefore, the second generated by the AC heating of the first conductive portion 32
It is possible to measure the temperature amplitude at the conductive part 42 as a resistance value. Further, the second conductive portion 42 is also provided in a state of being embedded by the auxiliary supporting film 50 and the film to be measured 60, similarly to the first conductive portion 32, so that heat loss due to radiation can be prevented. Yes, accurate measurement is possible.

According to the thermal diffusivity measuring apparatus 100 described above, the following operational effects are achieved.

Since the film to be measured 60 was supported by the supporting film 20 and the auxiliary supporting film 50 which were as thin as this, the influence of the thermal diffusivity of the supporting film 20 and the auxiliary supporting film 50 was calculated by using the calculation method described in detail later. The thermal diffusivity of the film 60 to be measured can be accurately measured except for.

Since the measurement region 24 is formed in a bridge shape and the lower part thereof communicates with the outside world, for example, by setting the side constant system in a vacuum state, the influence of heat transfer is eliminated and accurate measurement is performed. can do.

The first conductive portion 32 forming the heater and the second conductive portion 42 forming the electrode are provided close to each other under almost the same conditions, and they are in a buried state. The heating can be accurately controlled and the conduction heat can be accurately measured.

Further, since the measuring apparatus of this embodiment is small and the heating means 30 and the temperature detecting means 40 have a simple structure, the side constant system can be easily controlled and the measurement can be performed easily. You can

Next, the thermal diffusivity measuring device 100 shown in FIG.
The manufacturing process will be described with reference to FIGS. 3 and 4.

First, a support film 20 made of a silicon nitride film is formed on the surface of a substrate 10 made of silicon single crystal by low pressure CVD.
It is deposited by the method (FIG. 3 (A)). Then, a polysilicon film 32a is deposited on the surface of the support film 20 by the low pressure CVD method (FIG. 3 (B)). This polysilicon film 3
2a is doped with impurities such as phosphorus, arsenic or boron by an ion implantation method, and then patterned and etched by ordinary photolithography to form a first conductive portion 32 and a second conductive portion 42 (FIG. 3 (C)). The diffusion concentration of impurities at this time is not particularly limited, but for example, the temperature coefficient of resistance is 1000 ppm.
It is desirable to control the temperature to be / ° C or higher and the specific resistance to be 0.0001 Ωcm or higher. As shown in FIG. 5A, the first conductive portion 32 and the second conductive portion 42 are arranged so as to face each other with a distance L, and the shape thereof is a two-terminal structure having a U-shaped planar shape. It is said that.

Then, the first conductive portion 32 and the second conductive portion 32
An auxiliary support film 50 made of a silicon nitride film is deposited on the surface of the support film 20 by the low pressure CVD method so as to cover the conductive portion 42 of FIG. Then, this auxiliary support film 50
Film (SiO ₂ film) 60 to be measured on the surface of the
Are formed by a low pressure CVD method or the like (FIG. 3 (E)).

Next, contact holes H which communicate with the first conductive portion 32 and the second conductive portion 42, respectively, are formed in the measured film 60 and the auxiliary support film 50. (Fig. 4
(F)). Thereafter, a wiring film 70a made of aluminum is formed by a commonly used sputtering method (FIG. 4G), and the wiring films 70 and 72 having a predetermined shape are formed by patterning and etching the wiring film 70a (FIG. 4).
(H)).

Then, after forming a mask (not shown) having an opening corresponding to the shape of the external communication portion 12, the film 60 to be measured and the auxiliary film to be measured using an anisotropic etching solution such as KOH, TMAH or EDP. By anisotropically etching the support film 50 and the substrate 10, a predetermined portion corresponding to the mask pattern is removed to form the external communication portion 12. As shown in FIG. 4 (I) and FIG. 5 (B), the external communication portion 12 has a substantially square overall planar shape, and the supporting film 20, the auxiliary supporting film 50, and the film to be measured are arranged along the diagonal line thereof. A bridge-shaped measurement region 24 having a three-layer structure 60
Are formed. Since such a bridge has its longitudinal direction formed in the <110> direction of the silicon substrate having the (100) plane, the silicon substrate below the bridge can be removed by etching.

According to such a method of manufacturing a thermal diffusivity measuring device, a precise device can be manufactured by a thin film forming technique which is usually used in IC manufacturing. Then, by preparing a large number of devices in a state before forming the film to be measured 60 by batch processing and keeping them at all times, this can be used for various kinds of measurement objects, and the measurement device can be relatively used. It can be easily manufactured. Further, when the first conductive portion 32 and the second conductive portion 42 are formed, since photolithography is used as a patterning means, both can be manufactured with extremely high positional accuracy, and therefore the distance between them can be increased. L can be accurately defined.

Further, according to such a film forming method, the first
By forming the conductive part 32 and the second conductive part 42, the step of bonding the heater or the detector is not necessary, and it is not necessary to consider the influence of the adhesive material such as silver paste.

In the above process, the supporting film 2 is used.
0, the auxiliary support film 50 and the film to be measured 60 were etched to form the external communication portion 12, but the invention is not limited to this, and the support film 20 and the auxiliary support film are formed after the external communication portion 12 is formed on the substrate 10. The film 50 and the film 60 to be measured may be formed, and the films 20, 50 and 60 may be patterned.

Next, a thermal diffusivity measuring method using the thermal diffusivity measuring apparatus of this embodiment will be described.

First, the temperature amplitude Ta detected in the measurement region
c, the distance L between the first conductive portion 32 and the second conductive portion 42
The correlation with is explained.

The absolute value of the temperature amplitude Tac when AC heat Q having a constant frequency f is applied to the thermal diffusivity measuring apparatus is given by the following mathematical formula 5.
It is expressed as.

[Equation 5] From Equation 5, Equations 1 and 3 are derived.

In the equations 1 and 3, the damping constant k is represented by the equations 2 and 4.

From Expressions 1 and 3, the absolute value | Tac | of the temperature amplitude Tac is a linear function of the distance L. Therefore, the measurement is performed on two or more samples having different distances L, the correlation between the distance L and the temperature amplitude Tac is obtained, and the thermal diffusivity of the film to be measured is obtained by obtaining the attenuation constant k from the correlation diagram. You can

In the case of this embodiment, the film to be measured is the auxiliary support film 50 and S which are made of a silicon nitride film.
Since the composite film including the film to be measured 60 made of iO ₂ is formed, the thermal diffusivity actually obtained by the measuring device is obtained as that of the composite film. From the thermal diffusivity of 50 and the film thickness of both,
The thermal diffusivity of the film 60 to be measured can be calculated by the following equation 6.

[Equation 6] Further, the constant volume specific heat of the film to be measured is obtained from the amplitude of the AC temperature of the sample with respect to the amount of heat supplied by the heating means in an alternating manner, and the thermal conductivity of the film to be measured is obtained from the temperature rise of the film to be measured with respect to the amount of heat supplied be able to. The thermal diffusivity α, the thermal conductivity λ, and the constant volume specific heat c ′ are given by
Since it has the relationship shown in, the other one can be calculated by finding any two of these.

[Equation 7] Next, the measurement results obtained by actually using the measuring apparatus of this embodiment will be described. As a measuring device, as shown in FIG. 6, a distance L between the first conductive portion 32 and the second conductive portion 42
Six types of samples having different values were prepared. In addition, for each sample, the frequency of the applied AC voltage was changed in five steps for measurement. The results are shown in FIG. If the frequency is 1 kHz, the line indicated by reference symbol a indicates the reference symbol b
The line indicated by indicates a frequency of 2 Hz, the line indicated by c indicates a frequency of 4 Hz, and the line indicated by d indicates a frequency of 9 Hz.
And the curve indicated by the symbol e is for a frequency of 16 Hz.

From these measurement data, equations 3, 4 and 6
The thermal diffusivity of SiO ₂ is 0.054 cm ² /
S is obtained.

As described above, according to the thermal diffusivity measuring method of the present invention, the thermal diffusivity can be obtained with high accuracy and easily by using the measuring device of the present invention with few error factors.

Next, a modification of this embodiment will be described. Members having substantially the same configurations and functions as those shown in FIGS. 1 and 2 are designated by the same reference numerals, and detailed description thereof will be omitted.

FIG. 7 is a schematic plan view showing a first modification. In the thermal diffusivity measuring apparatus 200 of this modified example, the structure of the temperature detecting means 40 is different from that of the above embodiment. That is, the second conductive portion 42 has a four-terminal structure, and the constant current power source 44 and the voltmeter 46 are connected in parallel by separate wirings. In this way, by connecting the constant current power source 44 and the voltmeter 46 with different wirings, it is possible to accurately detect the resistance change only at the tip of the conductive portion 42, and thereby to perform accurate temperature measurement. In addition, the detection sensitivity can be increased by several digits by using a lock-in amplifier if necessary.

In the second modification shown in FIG. 8, the thermal diffusivity measuring device 300 does not use the auxiliary supporting film as in the above-described embodiment, but the measured film 60 is directly supported by the supporting film 20 (first conductive portion). 32, a region including the second conductive portion 34). In order to adopt such a configuration, the film-to-be-measured 60 needs to have uniform and good film-forming property by itself even without a base layer. By directly providing the film-to-be-measured 60 on the support film 20 in this way, the thermal characteristics of the film-to-be-measured 60 can be measured more accurately, and the manufacturing process is also simplified.

As a method of removing the silicon substrate under the bridge when forming the external communication portion 12, sacrificial layer etching can be used. In this case, before forming the support film 20, a sacrificial layer made of polysilicon is formed in advance in a region where a bridge is formed on the silicon substrate.

[0063]

According to the thermal diffusivity measuring apparatus of the present invention, the thermal diffusivity in the surface direction of various thin film samples having a thickness of about 1 μm can be measured with high accuracy by a relatively simple apparatus. it can.

Further, according to the method for manufacturing a thermal diffusivity measuring apparatus of the present invention, a highly accurate thermal diffusivity measuring apparatus can be manufactured with good reproducibility by a simple process.

Furthermore, according to the thermal diffusivity measuring method of the present invention, the thermal diffusivity can be obtained with high accuracy.

[Brief description of drawings]

FIG. 1 is a perspective view schematically showing a thermal diffusivity measuring apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a state in which a heating unit and a temperature detecting unit are added to the measuring device shown in FIG.

3A to 3E are sectional views schematically showing a manufacturing process of the thermal diffusivity measuring apparatus shown in FIG.

4 (F) to (I) are cross-sectional views schematically showing a process following the manufacturing process shown in FIG.

5 (A) is a plan view of the device shown in FIG. 3 (C),
FIG. 4B is a plan view of the device shown in FIG.

6 is a diagram showing a relationship between a distance between a first conductive portion and a second conductive portion and a temperature amplitude in an actual measurement example performed by using the thermal diffusivity measuring apparatus shown in FIG.

FIG. 7 is an explanatory diagram showing a modified example of the embodiment of the present invention.

FIG. 8 is a sectional view showing another modification of the present invention.

[Explanation of symbols]

 10 substrate 12 external communication part 20 support film 22 support part 24 measurement region 30 heating means 32 first conductive part 40 temperature detecting means 42 second conductive part 60 measured film 62 measured part 100, 200, 300 thermal diffusivity measuring device

Claims (3)

[Claims] 1. An insulating thin film, comprising: a substrate having an external communication portion opened upward; and a support portion formed on the substrate and erected in a bridge shape on a portion of the external communication portion. A heating means having a support film, a first conductive part formed on the support film, at least one end of which is located in the support part, and an AC power supply electrically connected to the first conductive part. A second conductive portion formed on the support film, at least one end of which is located in the support portion, and which is located at a predetermined distance from the first conductive portion; and the second conductive portion. Temperature detecting means having a resistance measuring part electrically connected to the conductive part, and a bridge-shaped measured object formed at least over a region including the support part, the first conductive part and the second conductive part. A film to be measured having a portion, and Wherein, the thermal diffusivity measuring apparatus of a thin film. 2. A heating means is formed by forming a support film made of an insulating thin film on a silicon substrate, and patterning and etching by photolithography after forming a conductive film on the support film. A step of forming a first conductive portion and a second conductive portion constituting the temperature detecting means, and forming a film to be measured so as to cover at least a region including the first conductive portion and the second conductive portion. And a part of the silicon substrate under the support film is removed by anisotropic etching to form a bridge-shaped measurement region including the first conductive portion and the second conductive portion, and to connect the external communication portion. A method of manufacturing a thermal diffusivity measuring apparatus, comprising: 3. The thermal diffusivity measuring device according to claim 1, wherein the measuring device comprises two or more thermal diffusivity measuring devices having different distances L between the first conductive part and the second conductive part. The thermal diffusivity is characterized by measuring the temperature amplitude Tac in each of the above, obtaining the damping constant k from the correlation between the distance L and the temperature amplitude Tac obtained from the following equation 1, and obtaining the thermal diffusivity α from the following equation 2. How to measure the rate. [Equation 1] [Equation 2]