JP2771450B2 - Temperature measuring element and temperature measuring method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature measuring element and a temperature measuring method using a novel material having high thermoelectric conversion performance.

[0002]

2. Description of the Related Art The history of research on thermoelectric effects is very long.
Power generation and cooling using the thermoelectric effect are very economical.
Despite expected social benefits, 1950s
Bi of _TwoTe_ThreeSince the development of thermoelectric materials
I don't show the exhibition. This is due to the improvement of the thermoelectric conversion figure of merit.
The thermoelectric conversion performance
The emergence of high new materials has been desired. Also the thermoelectric effect
The same applies to the case of a temperature measuring element using
New thermoelectric material with high exchangeability and excellent temperature measurement accuracy
Appearance was desired.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a temperature measuring element and a temperature measuring method using a novel material having high thermoelectric conversion performance.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a semiconductor device having a silicon substrate and an antimony layer formed on the silicon substrate, wherein a temperature is determined based on a thermoelectromotive force generated between different portions on the antimony layer. This is achieved by a temperature measuring element characterized in that Further, it is desirable that the temperature measuring element measures a temperature in a range of about 200K to about 435K.

[0005] Another object of the present invention is to provide a temperature measuring device having a silicon substrate and an antimony layer formed on the silicon substrate, wherein a first portion of the antimony layer is set as a reference temperature, and And a second portion different from the first portion and the second portion is measured to measure the thermoelectromotive force between the first portion and the second portion.
Is achieved by measuring the temperature in the range of

[0006]

According to the present invention, a temperature is measured based on a thermoelectromotive force generated between different portions of an antimony thin film using a novel thermoelectric material having a high thermoelectric conversion performance in which an antimony thin film is formed on a silicon substrate. As a result, temperature measurement with excellent temperature measurement accuracy can be realized.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present inventors have focused on a thin film material instead of a conventional bulk material in order to overcome the current situation where the thermoelectric conversion performance index of the conventional thermoelectric material has reached a plateau. A thin film of a constituent element of a thermoelectric material used as a bulk material was deposited on a single crystal substrate, and the thermoelectric conversion performance of the thin film was measured. As a result, they found a combination of a single-crystal substrate and a thin-film material having an unusually large thermoelectric conversion performance as compared with the bulk material, and came to the idea of using it for temperature measurement.

The present inventors used a silicon (Si) substrate as a single crystal substrate and used antimony (S) as a thermoelectric material.
b) or a sample was produced by molecular beam cell MBE using bismuth (Bi) and antimony (Sb). An Sb thin film or a Bi / Sb superlattice layer in which a Bi thin film and an Sb thin film were alternately laminated was formed on a Si substrate having a (111) surface, and the temperature dependence of thermoelectric power was measured for each sample. . The Sb thin film was also formed on a glass substrate.

The details of the manufactured samples are as follows. Example A 290 nm thick Sb thin film was formed on a Si substrate. Comparative Example 1 An Sb thin film having a thickness of 335 nm was formed on a glass substrate. Comparative Example 2 A total of 20 Bi thin films having a thickness of 5.2 nm and an Sb thin film having a thickness of 0.4 nm were alternately laminated on a Si substrate to form a Bi / Sb superlattice layer having a thickness of 112 nm.

The present inventors measured thermoelectric conversion performance of these samples. The measurement method performed by the inventors of the present application will be described with reference to FIG. Two brass sample stages 10a and 10b for holding the sample 14 are provided at a predetermined interval. On one sample stage 10b,
A small hole is provided on the side surface so that the sample stage 10b can be heated, and the heater 12 is inserted therein. A heat-dissipating wire (not shown) is connected to the other sample stage 10a. The sample 14 is placed on the sample tables 10a and 10b. By heating the heater 12, a temperature difference of about several degrees occurs between the sample stage 10a side and the sample stage 10b side of the sample 14.

To measure the temperature of the sample 14 on the sample stage 10a and the temperature of the sample 14 on the sample stage 10b, copper-constantan thermocouples 16 and 18 are placed on both ends of the sample 14 on the upper surface of the sample 14. Is provided. Further, in order to measure the thermoelectromotive force generated due to the temperature difference between the sample table 10a side and the sample table 10b side of the sample 14, the thermoelectric power measurement lead wires 20 and 22 are provided at both ends of the sample 14.

The sample 14 is placed on the sample tables 10a and 10b. The thermocouples 16 and 18 are set at both ends of the sample, and the thermoelectric power measurement leads 20 and 22 are set.
Thereafter, the above-described measuring device is installed inside a metal container (not shown), and the thermoelectromotive force at that time is measured while changing the temperature inside the container. The measurement temperature range is about 10
The temperature was raised from 100 [K] at a rate of about 1 ° C./min from 0 [K] to around 400 [K].

The temperature of the sample 14 on the sample stage 10a side is set to T1.
[K], the temperature of the sample 14 on the sample stage 10b side is set to T2 [K].
Assuming that the temperature difference ΔT [K] = T2−T1 is given to the sample 14 and the thermoelectromotive force at that time is ΔV [μV], the Seebeck coefficient α is expressed by the following equation α = ΔV / ΔT [ μV / K].

For each of the example and comparative examples 1 and 2, the thermoelectromotive force was measured by changing the temperature around the sample 14. 2 to 4 show the measurement results. 2 to 4
The horizontal axis indicates the temperature T1 [K] on the sample stage 10a side and the sample stage 1
0b side temperature T2 [K] arithmetic mean temperature ((T1 + T
2) / 2 [K]), and the vertical axis represents Seebeck (See).
beck) coefficient α [μV / K].

FIG. 2 shows the measurement results of the embodiment, FIG. 3 shows the measurement results of Comparative Example 1, and FIG. 4 shows the measurement results of Comparative Example 2. As shown in FIG. 2, the Seebeck coefficient of the embodiment in which the Sb thin film is formed on the silicon substrate has a temperature of 200.
Below [K], a positive value of 10 [V / K] or less is shown. However, when the temperature becomes 200 [K] or more, the Seebeck coefficient turns to the negative side and sharply increases to about 400 K.
[K] was found to reach -300 [μV / K].

Further, the measurement was repeated three times up to a temperature around 400 [K]. No decrease in the Seebeck coefficient was observed with an increase in the number of measurements, and reproducibility of the thermoelectric conversion performance was also recognized. As shown in FIG. 3, the Seebeck coefficient of Comparative Example 1 in which an Sb thin film was formed on a glass substrate increased with increasing temperature, but even at 300 [K], the value was as small as about 34 [μV / K]. It is not enough as a temperature measuring element. In addition, although the characteristics of bulk Sb are also shown in the figure, only characteristics comparable to those of bulk Sb could be obtained.

As shown in FIG. 4, Bi on a silicon substrate
The Seebeck coefficient of Comparative Example 2 in which the / Sb superlattice layer was formed increased to the minus side as the measurement temperature increased,
At 400 [K], a high value of about -250 [V / K] could be obtained. However, the value decreases as the measurement is repeated, and becomes -140 at 400 [K] after the second measurement.
It deteriorated to near [μV / K].

As described above, according to the present embodiment, in the sample in which the Sb thin film is formed on the silicon substrate, the Seebeck coefficient increases to the minus side as the temperature rises, and about 40
At 0 [K], a very large thermoelectric conversion performance of -300 [μV / K] was obtained. Further, even when the measurement was repeatedly performed at a temperature of 400 [K] or less, the value did not deteriorate.

Note that such an effect can be obtained by forming S on a glass substrate.
No results were obtained in Comparative Example 1 in which the b thin film was formed, or in the case of the Bi / Sb superlattice film. The inventors of the present application considered as follows from the above measurement results. For the sample in which the Sb thin film was formed on the silicon substrate, the temperature dependence of the electric resistance was measured in addition to the temperature measurement of the Seebeck coefficient.
Between 00 [K] and 400 [K], a metallic behavior in which the resistance value monotonously increased was shown. This means that although Sb changed from p-type to n-type with the rise in temperature, it did not suddenly affect the electrical conductivity. In a semimetal, the carrier concentration of electrons and holes is equal, but the mobility is different. Thermoelectric studies have revealed that the relationship between the carrier concentrations becomes unbalanced in an Sb thin film deposited on a silicon substrate. It is thought that a mechanism occurred and led to the above-described results.

Next, considering the practical application of the sample of the above-described embodiment as a temperature measuring element, the temperature measuring range of the temperature measuring element of the present invention will be considered. The lower limit temperature of the temperature measurement range is a temperature at which the Seebeck coefficient changes from the positive side to the negative side and falls below zero. From the graph in FIG.
The lower limit temperature of the temperature measuring range of the temperature measuring element of the present invention is about 2
It is about 00K.

The upper limit temperature of the temperature measurement range is the highest temperature at which the Seebeck coefficient does not decrease and deteriorate even when the temperature is repeatedly increased. From the graph of FIG. 2, the upper limit temperature of the temperature measurement range of the temperature measurement element of the present invention is about 435K. Therefore, the measurement range of the temperature measuring element of the present invention is in the range of about 200K to about 435K.

Next, in order to measure the temperature with the temperature measuring element of the present invention, it is necessary to adopt a configuration in which a temperature difference occurs between different portions of the Sb thin film formed on the silicon substrate. 5 and 6 show specific examples of the temperature measuring element of the present invention. In a first specific example, as shown in FIG.
Temperature measuring element chip 34 on which Sb thin film 32 is formed
Are placed in the envelope 36. External terminals 38 and 40 for measuring the thermoelectromotive force are provided below the envelope 36. These external terminals 38 and 40 and the left and right portions of the temperature measuring element chip 34
2 and 44 are wire-bonded. On the upper surface of the envelope 36, a shielding plate 46 for shielding heat rays is provided. A window 48 is formed in the shielding plate 46 so that the right half of the temperature measuring element chip 34 is exposed.

Since heat rays from the outside are shielded by the shielding plate 46, only the right half of the temperature measuring element chip 34 below the window 48 of the shielding plate 46 is heated, and the temperature measuring element chip 34 is heated.
A temperature difference between the left and right portions of the device. Second
6, the basic configuration is the same as that of the first specific example shown in FIG. 5, but instead of providing the shielding plate 46, the left half of the temperature measuring element chip 34 is provided. Reflective film 5
The difference from the first specific example is that 0 is provided. Since heat rays from the outside are reflected by the reflection film 50, only the right half of the temperature measurement element chip 34 that is not covered with the reflection film 50 is heated, and a temperature difference occurs between the left and right portions of the temperature measurement element chip 34. Can be done.

[0024]

As described above, according to the present invention, a novel thermoelectric material having a high thermoelectric conversion performance in which an Sb thin film is formed on a silicon substrate is used, based on the thermoelectromotive force generated between different portions of the Sb thin film. Since the temperature is measured by the temperature measurement, it is possible to realize temperature measurement excellent in temperature measurement accuracy.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a method for measuring thermoelectric conversion performance for samples of an example and a comparative example.

FIG. 2 is a graph showing the temperature dependence of the Seebeck coefficient of an example in which an Sb thin film is formed on a silicon substrate.

FIG. 3 is a graph showing the temperature dependence of the Seebeck coefficient of Comparative Example 1 in which an Sb thin film was formed on a glass substrate.

FIG. 4 is a graph showing the temperature dependence of the Seebeck coefficient of Comparative Example 2 in which a Bi / Sb superlattice layer was formed on a silicon substrate.

FIG. 5 is a diagram showing a first specific example of the temperature measuring element of the present invention.

FIG. 6 is a view showing a second specific example of the temperature measuring element of the present invention.

[Explanation of symbols]

 10a, 10b: sample table 12: heater 14, sample 16, 18: thermocouple 20, 22, thermoelectric power measurement lead wire 30: Si substrate 32: Bi / Sb superlattice layer 34: temperature measurement element chip 36: surrounding Containers 38, 40: External terminals 42, 44: Bonding wires 46: Shielding plate 48: Windows 50: Reflective film

Continuation of the front page (56) References JP-A-3-233980 (JP, A) JP-A-63-43381 (JP, A) JP-A-4-360588 (JP, A) Table 6-501550 (JP) , A) (58) Field surveyed (Int. Cl. ⁶ , DB name) G01K 7/02 H01L 35/18

Claims (3)

(57) [Claims] 1. A semiconductor device comprising: a silicon substrate; and an antimony thin film formed on the silicon substrate, wherein a temperature is measured based on a thermoelectromotive force generated between different portions on the antimony thin film. Temperature measuring element. 2. The temperature measuring device according to claim 1, wherein
A temperature measuring element for measuring a temperature in a range from about 200K to about 435K. 3. A temperature measuring element having a silicon substrate and an antimony thin film formed on the silicon substrate, wherein a first portion of the antimony thin film is used as a reference temperature,
A temperature in a range from about 200K to about 435K is measured by measuring a thermoelectromotive force between the first part and the second part with a second part different from the first part as a measurement part. A temperature measuring method.