WO2012147432A1 - Thermometry resistor and thermometer - Google Patents

Thermometry resistor and thermometer Download PDF

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Publication number
WO2012147432A1
WO2012147432A1 PCT/JP2012/057016 JP2012057016W WO2012147432A1 WO 2012147432 A1 WO2012147432 A1 WO 2012147432A1 JP 2012057016 W JP2012057016 W JP 2012057016W WO 2012147432 A1 WO2012147432 A1 WO 2012147432A1
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Prior art keywords
thermometer
chromium nitride
substrate
temperature
less
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PCT/JP2012/057016
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French (fr)
Japanese (ja)
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四谷任
田中峰雄
石田武和
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公立大学法人大阪府立大学
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Publication of WO2012147432A1 publication Critical patent/WO2012147432A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K7/00—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements
    • G01K7/16—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements
    • G01K7/22—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements the element being a non-linear resistance, e.g. thermistor
    • G01K7/223—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements the element being a non-linear resistance, e.g. thermistor characterised by the shape of the resistive element
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01C—RESISTORS
    • H01C7/00—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material
    • H01C7/04—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material having negative temperature coefficient
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01C—RESISTORS
    • H01C7/00—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material
    • H01C7/04—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material having negative temperature coefficient
    • H01C7/041—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material having negative temperature coefficient formed as one or more layers or coatings

Definitions

  • the present invention relates to a resistance temperature detector and a cryogenic thermometer using the same.
  • thermometer having the following characteristics is required as a thermometer used under conditions of extremely low temperature and high magnetic field.
  • the disturbance due to the magnetic field is small.
  • Sensitivity hereinafter, the sensitivity is assumed to be an absolute value
  • Excellent stability against thermal cycle is high.
  • Wide temperature measurement area It is made of a material having high thermal conductivity.
  • the heat capacity is small. (7) It can be manufactured at low cost.
  • thermometer As a thermometer having such characteristics, a resistance temperature detector was provided in which a chromium nitride thin film having a thickness of 50 to 1000 nm was provided on a substrate, and the nitrogen content in the chromium nitride thin film was 40 to 60 atomic%.
  • a thermometer (see, for example, Patent Document 1) is known. This type of thermometer has the above-mentioned characteristics in a well-balanced manner, and is particularly excellent in stability against a thermal cycle, and can measure temperature in a wide magnetic field range.
  • the chromium nitride in Patent Document 1 is confirmed to be Cr 2 N, as shown in a comparative example (FIG. 3) described later in which Example 1 described in Patent Document 1 was added.
  • the chromium nitride described in Document 1 is presumed to contain excess nitrogen in Cr 2 N.
  • the conventional thermometer can measure the temperature without being affected by the magnetic field under the conditions of extremely low temperature and high magnetic field.
  • a thermometer that is less affected by a magnetic field and can measure a wider temperature range.
  • the present invention has been devised in view of the above problems, and provides a resistance temperature detector and a thermometer that are not easily affected by a magnetic field and enable temperature measurement in a wide temperature range from room temperature to extremely low temperature. With the goal.
  • the characteristic structure of the resistance temperature detector according to the present invention for achieving the above object is that chromium nitride which becomes antiferromagnetic at least 100K or less is used as a material.
  • the present inventors paid attention to the fact that the magnetoresistive effect of the antiferromagnetic semiconductor is small, and as a result of intensive studies, the temperature dependence of the magnetoresistive effect is reduced by using the antiferromagnetic semiconductor as a material for the resistance temperature detector. As a result, the present invention has been found. On the other hand, as shown in Example 2 (FIG. 4) described later, some chromium nitrides begin to dislocation to antiferromagnetism at around 220K and become antiferromagnetic at a low temperature range of 100K or less.
  • chromium nitride can be manufactured at low cost, the manufacturing cost of the resistance temperature detector can be reduced. In addition, since chromium nitride is not easily affected by water or moisture, the conditions under which a resistance temperature detector can be used are expanded. Further, since chromium nitride is a binary system and has a stable structure, a resistance temperature detector having the same individual characteristics (compatible) can be manufactured. For this reason, a large number of thermometers with uniform temperature characteristics can be supplied.
  • thermometer The characteristic configuration of the thermometer according to the present invention is that a chromium nitride film which becomes antiferromagnetic at least 100K or less is provided on a substrate.
  • This configuration can provide a thermometer that is not easily affected by a magnetic field and that can measure a wide temperature range from room temperature to extremely low temperatures.
  • the chromium nitride film is preferably formed of a thin film in which crystal growth of the chromium nitride is suppressed, and the crystal grain size is preferably 15 nm or less.
  • the chromium nitride film suppresses crystal growth of chromium nitride and has a crystal grain size of 15 nm or less, so that the magnetoresistance effect of chromium nitride can be reduced.
  • the substrate preferably has a thermal expansion coefficient in the range of 1 ⁇ 10 ⁇ 6 to 5 ⁇ 10 ⁇ 6 / K.
  • the substrate is preferably a silicon substrate, and an electrical resistivity is preferably 7000 ⁇ cm or more.
  • the electrical resistivity is 7000 ⁇ cm or more, the electrical resistivity becomes higher in the low temperature range, and therefore it can be applied as a thermometer substrate. For this reason, it is possible to use a high-resistance silicon substrate that is easily available.
  • thermometer it is preferable that a pair of electrodes are arranged at a predetermined inter-electrode distance on the chromium nitride film to increase measurement sensitivity in a specific temperature range.
  • thermometer setting method is a thermometer in which a chromium nitride film that becomes antiferromagnetic at least 100K or less is provided on a substrate, and a pair of electrodes provided on the chromium nitride film By changing the distance between the electrodes, a temperature range with high measurement sensitivity is set.
  • Example 3 since the absolute sensitivity Sa is in the vicinity of 1 over 1K to 300K, chromium nitride has a pair of chromium nitride films provided on the chromium nitride film.
  • ⁇ / K
  • thermometer manufacturing method is characterized in that a substrate and metallic chromium are arranged in a film forming chamber, and nitrogen or a mixture of nitrogen and a rare gas so that the atmosphere has a nitrogen ratio of 80% or more.
  • a gas is introduced to react metal chromium and nitrogen to form a chromium nitride film that becomes antiferromagnetic at least 100 K or less on the substrate.
  • a chromium nitride film that becomes antiferromagnetic at least at 100K or less can be formed on a substrate, so that it is difficult to be affected by a magnetic field, and a wide temperature range from room temperature to extremely low temperature is measured.
  • a thermometer can be made.
  • thermometer manufacturing method when the metal chromium and nitrogen are reacted, the crystal growth of chromium nitride can be suppressed and the particle size can be reduced by keeping the substrate at 100 ° C. or lower. preferable.
  • the crystal grain size of chromium nitride formed on the substrate can be reduced by keeping the substrate at 100 ° C. or lower.
  • thermometer 2 is a graph showing the results of crystal structure analysis of chromium nitride produced in Example 1 by X-ray diffraction. It is a graph which shows the crystal structure analysis result by the X-ray diffraction method of the chromium nitride produced by the comparative example. It is a graph which shows that the chromium nitride produced in Example 1 transfers to antiferromagnetism. It is a graph which shows the temperature and resistance characteristic of the thermometer produced in Example 3, and the temperature dependence of absolute sensitivity. It is a graph which shows the change of an electrical resistance when the thermometer produced in Example 3 is made to cycle 27 times between 4K and 300K.
  • thermometer produced in Example 3 is a graph showing a change in electric resistance value when a thermometer in which only the substrate is changed to a SiO 2 substrate is cycled twice between 4K and 300K. It is a graph which shows the change of the temperature error when the thermometer produced in Example 3 is changed to 9T at 4K and 2K. It is a graph which shows the change of the electrical resistance value of the chromium nitride thin film produced by changing nitrogen partial pressure by the reactive RF magnetron sputtering method.
  • the resistance temperature detector according to the present invention is made of chromium nitride that becomes antiferromagnetic at least 100K or less.
  • the thermometer according to the present invention is provided with a chromium nitride film that becomes antiferromagnetic at least 100K or less on a substrate. According to the present invention, measurement in a wide temperature range from room temperature to extremely low temperature (for example, about 300 K to 1 K) can be performed without being affected by a magnetic field.
  • chromium nitride has a stable structure and can be manufactured at low cost, it is possible to supply a large number of thermometers with uniform characteristics (compatible) at a low manufacturing cost.
  • thermometer since chromium nitride is not easily affected by water and moisture, the versatility of the thermometer is enhanced. For example, as shown in FIG. 1, by providing a chromium nitride film 2 on a 1 mm square substrate 1 and forming electrodes 3 and 4 thereon, a temperature that is small and has a low heat capacity and can be mass-produced inexpensively. It can be used as a total of ten.
  • thermometer since the electric resistance of metal decreases with a decrease in temperature, it is not possible to provide a thermometer with high sensitivity from cryogenic temperature to room temperature.
  • the nitride can break down the crystal structure by producing an excessive or insufficient nitrogen-containing thin film, and the function of the thermometer can be expressed by localizing the underlying electrons.
  • the conventional thermometer achieves an increase in electrical resistance as the temperature decreases by putting excessive nitrogen or nitrogen in the metal nitride in a significantly excessive or insufficient state and making the metal electrons localized, thereby reducing the temperature.
  • a device that can measure a state with high sensitivity is known. That is, the crystal structure of the metal thin film is disturbed by nitrogen, and the function of the thermometer is expressed.
  • thermometer exhibits excellent characteristics, it is difficult to eliminate variations among individual products as a thermometer because the structure is disturbed in various ways.
  • the chromium nitride one that becomes antiferromagnetic at least 100K or less is used. It is preferable that chromium nitride is antiferromagnetic even at a temperature higher than 100K, but it is preferable. However, when the temperature is high, the influence of the magnetoresistive effect is reduced, and therefore antiferromagnetic at least 100K or less. Then, temperature measurement in a wide temperature range from room temperature to extremely low temperature is possible even under a high magnetic field such as 10T. For example, as shown in FIG. 2, the chromium nitride used in the examples described later starts to dislocation to antiferromagnetism at around 220K, and is reliably antiferromagnetic at a low temperature range of 100K or less.
  • the chromium nitride film is preferably composed of a thin film in which the crystal growth of chromium nitride is suppressed.
  • the crystal grain size of chromium nitride is preferably 15 nm or less, more preferably 10 nm or less, and further preferably 5 nm or less.
  • the substrate on which the chromium nitride film is provided is not particularly limited, but preferably has a thermal expansion coefficient in the range of 1 ⁇ 10 ⁇ 6 to 5 ⁇ 10 ⁇ 6 / K.
  • a thermal expansion coefficient in the range of 1 ⁇ 10 ⁇ 6 to 5 ⁇ 10 ⁇ 6 / K.
  • the stability of the thermal cycle can be further improved.
  • examples of such a substrate include a silicon wafer and sapphire. Among these, a silicon wafer is preferable, and a silicon wafer having an electrical resistivity of 7000 ⁇ cm or more is particularly preferable.
  • such a substrate is not only easily available, but also has a substrate base with a thickness of 500 ⁇ m, and if the electrical resistivity at room temperature is 7000 ⁇ cm or more, the electrical resistivity increases as the temperature decreases. Even if not, it can be preferably applied as a substrate of the thermometer according to the present invention.
  • thermometer according to the present invention can be manufactured by a conventionally known apparatus using antiferromagnetic chromium nitride as a material.
  • the manufacturing method is not particularly limited, for example, it can be manufactured by the following method.
  • the substrate is cleaned according to a conventional method.
  • a silicon wafer or the like is used as a substrate, it can be used as it is.
  • an SiO 2 layer having a thickness that can keep electric insulation on the surface or an electric insulating layer using another material may be formed in advance.
  • a chromium nitride (CrN) thin film is formed on the substrate by sputtering (for example, reactive RF magnetron sputtering).
  • the inside of the film forming chamber in which the substrate and the Cr target are set is set to 1.3 ⁇ 10 ⁇ 3 Pa or less, more preferably to about 7 ⁇ 10 ⁇ 5 Pa.
  • Ar is introduced into the film forming chamber so that the internal pressure becomes about 1 Pa, and pre-sputtering for purifying the surface of the Cr target is performed.
  • the inside of the film forming chamber is evacuated again until the degree of vacuum is the same as the above degree of vacuum, and N 2 is introduced.
  • the flow rate of N 2 is, for example, about 20 sccm. Further, if necessary, N 2 may be diluted with Ar. In that case, the total flow rate is preferably about 30 sccm.
  • the partial pressure of N 2 at this time is preferably 1 Pa 80% to 100% (N 2 only), particularly preferably 1 Pa 100%.
  • the substrate temperature is maintained at room temperature (about 25 ° C.) to about 200 ° C., and the film forming power is about 4 to 8 W / cm 2 to obtain a thickness of 25
  • a sputtering operation is performed until a chromium nitride thin film of about ⁇ 1000 nm is formed.
  • the temperature of the substrate is not limited to the range of room temperature to 200 ° C., but if it becomes lower than 100 ° C., the influence of moisture adsorbed on the substrate starts to appear, and the reproducibility and adhesion may be adversely affected.
  • the substrate temperature is the highest experience temperature for the film. When used as a thermometer, the entire device used may be heated to about 100 ° C.
  • the temperature of the substrate is preferably 200 ° C. or less, and more preferably 100 ° C. or less.
  • the crystal grain growth is suppressed by maintaining the substrate at 100 ° C. or lower when reacting Cr and N 2.
  • the crystal grain size of chromium nitride can be reduced.
  • the thermometer according to the present invention can be obtained by forming electrodes on the CrN thin film by, for example, vacuum deposition or sputtering.
  • the electrode material known materials can be used, and examples thereof include Ag, Cr, Au, Cu, Al, V, In, Pt, Rh, Ti, and Nb.
  • Nb is a silicon wafer or CrN. This is particularly preferable because it is well-suited to a thin film, easily realizes ohmic contact, and improves thermal cycle stability.
  • the distance between the electrodes when the electrodes are formed on the CrN thin film can be set as appropriate according to the temperature range in which the measurement sensitivity is desired to be increased because the electric resistance value varies depending on the distance. That is, as the electric resistance value of the thermometer, it is easy to measure around 1 k ⁇ , and therefore it is preferable to set the inter-electrode distance so that the resistance value in a desired temperature range is around 1 k ⁇ .
  • Example 1 A chromium nitride thin film was formed on the substrate by reactive RF magnetron sputtering, and the crystal structure of the chromium nitride thin film was analyzed by X-ray diffraction. The results are shown in FIG. Sputtering was performed under the following conditions.
  • Substrate High resistance Si wafer (nominal 10 k ⁇ cm or more, actual measurement 20 k ⁇ cm), diameter 100 mm, thickness 500 ⁇ m
  • Substrate temperature Since the substrate is heated by plasma during sputtering, the heater is not heated, but it is ⁇ 100 ° C.
  • Substrate SiO 2 (10 mm square, thickness 0.3 mm)
  • Substrate temperature 300 ° C Degree of vacuum: 5 ⁇ 10 ⁇ 4 Pa
  • Target Metal Cr (diameter 100mm x thickness 5mm)
  • Sputtering gas: Ar Reactive gas: Nitrogen Gas flow rate: 6sccm N 2 / (Ar + N 2 ) 50% Film forming power: 200W
  • Substrate temperature 300 ° C Chromium nitride thin film thickness: 250nm
  • Example 2 From FIG. 2, it was found that the chromium nitride thin film produced in Example 1 was CrN. 2 and 3, the chromium nitride thin film produced in Example 1 and the chromium nitride thin film produced in the comparative example have different crystal structures (peak positions in X-ray diffraction) and were produced in the comparative example.
  • the chromium nitride thin film was found to be Cr 2 N.
  • the crystal grain size of chromium nitride was calculated from the Debye-Scherrer equation and found to be 2.1 nm and 2.3 nm, respectively.
  • Debye-Scherrer equation: D K ⁇ ⁇ / B ⁇ cos ⁇
  • D crystal grain size
  • ⁇ wavelength used for measurement (X-ray CuK ⁇ ray: 0.154 nm)
  • B half-width
  • ⁇ diffraction angle
  • K proportional constant is assumed to be 0.9
  • Example 2 The magnetism of the chromium nitride thin film produced in Example 1 was measured with a superconducting quantum interferometer (SQUID). As a result, as shown in FIG. 4, it was confirmed that chromium nitride began to dislocation to antiferromagnetism at around 220K and became antiferromagnetic at a low temperature range of 100K or less.
  • Example 3 A pair of electrodes (Nb) was formed on the chromium nitride thin film produced in Example 1, and a thermometer was produced. The temperature / resistance characteristics of this thermometer and the temperature dependence of absolute sensitivity were examined and are shown in FIG.
  • the chromium nitride thin film having a distance between electrodes of 50 ⁇ m had an electric resistance of 9 ⁇ at room temperature, an absolute sensitivity of 0.9, and a temperature resolution at room temperature of 3 mK or less.
  • the electrical resistance was 1100 ⁇
  • the absolute sensitivity was 1.6
  • the temperature resolution was 0.2 mK or less.
  • the absolute sensitivity was 2.5 even at 1K, and it was found that it can be used up to about 0.3K when extrapolated.
  • thermometer Since the thermometer is easy to measure when the electrical resistance value is around 1000 ⁇ , the above thermometer has a high measurement sensitivity around 4K from FIG.
  • the required differential sensitivity changes depending on the performance of the measuring instrument. For example, when the number of digits of the resistance value that can be read is small, a large differential sensitivity
  • the absolute temperature of the chromium nitride thin film is almost 1 over a wide temperature range, and therefore, only by setting the distance between the electrodes without changing the material and manufacturing conditions of the resistance temperature detector, The electrical resistance value can be adjusted to a value that is most easily measured, and the differential sensitivity suitable for the temperature range of the characteristic can be set.
  • thermometer of this example with the distance between the electrodes changed and the one using a platinum resistance thermometer (100 ⁇ at 300K) used for precise temperature measurement near room temperature.
  • Table 1 The results are shown in Table 1. According to this, it was confirmed that a thermometer having the same sensitivity as that of a platinum resistance temperature detector specialized in temperature measurement at room temperature can be produced simply by changing the distance between the electrodes to 500 ⁇ m.
  • the distance between the electrodes may be 5 mm.
  • Example 4 Using the thermometer produced in Example 3, the change in electrical resistance was investigated by cycling 27 times between 4K and 300K, and is shown in FIG. Moreover, the measurement result of the electrical resistance at 4K at that time is shown in FIG. From FIG. 6, the standard deviation at 4K was 0.98 ⁇ , and the temperature shift calculated from the coefficient of variation was 2 mK or less. It was found that the temperature control stability of PPMS (Physical Properties Measurement System) manufactured by Quantum-Design, which was used for the measurement, was about 0.2%, and the resistance change due to the thermal cycle did not change within the control error.
  • PPMS Physical Properties Measurement System
  • thermometer produced in Example 3 was also subjected to a cycle between 4K and 300K twice for the case where only the substrate was changed to fused silica (SiO 2 ), and the change in electric resistance was examined. As a result, as shown in FIG. 8, it was found that the thermal cycle stability was lower than that using Si as the substrate.
  • Example 5 Using the thermometer produced in Example 3, the change in temperature error when the magnetic field was changed up to 9T at 4K and 2K was shown in FIG. As a result, the change in temperature error was 6 mK or less at any temperature.
  • the measurement was performed with PPMS (Physical Properties Measurement System) manufactured by Quantum-Design, but the temperature control accuracy was 8 mK, which was comparable to the temperature measurement error due to the magnetic field. From the above, it was found that the chromium nitride in the present invention has a very small magnetoresistance effect, and the temperature dependence of the temperature measurement error due to the magnetoresistance effect is extremely small.
  • thermometer of this example is not sensitive to a magnetic field and can measure a wide temperature range of 0.3 to 400K.
  • Example 6 The electric resistance of the thin film when a chromium nitride thin film is formed while changing the nitrogen partial pressure at a film forming power of 200 W and a substrate temperature of 200 ° C. by the reactive RF magnetron sputtering method and the reactive DC magnetron sputtering method, respectively. Changes were examined and the results are shown in FIGS. In both the reactive RF magnetron sputtering method and the reactive DC magnetron sputtering method, the electric resistance value of the chromium nitride thin film once increased with increasing nitrogen partial pressure, and then gradually decreased.
  • the nitrogen partial pressure when the electric resistance reached the peak was about 7% (between 5% and 10%), whereas the reactive DC magnetron.
  • the sputtering method it was about 40%, which was greatly different. From this result, it was found that the reactive RF magnetron sputtering method is more easily nitrided and preferable.
  • the temperature dependence of the electrical resistance value in a chromium nitride thin film produced by a reactive RF magnetron sputtering method was examined. As a result, as shown in FIG. 12, when the nitrogen partial pressure was increased, it was found that the temperature dependence of the electrical resistance value of the chromium nitride thin film was lowered. That is, it was found that the nitrogen partial pressure in the sputtering method when producing a chromium nitride thin film is preferably high, more preferably 80% or more, and even more preferably 100%.
  • Example 7 In the case of forming a chromium nitride thin film by reactive RF magnetron sputtering with a nitrogen partial pressure of 100% and a film forming power of 200 W (2.5 W / cm 2 ) and 600 W (7.6 W / cm 2 ), respectively.
  • the temperature dependence of the electrical resistance of the thin film was investigated. As a result, as shown in FIG. 13, when the film forming voltage is 600 W, it can be used as a thermometer up to 2K, whereas in the case of 200 W, the electric resistance value of the formed thin film exceeds 7 M ⁇ at 7K.
  • the film forming voltage in the reactive RF magnetron sputtering method is preferably 500 W (6.4 W / cm 2 ) or more, and 600 W (7. 6 W / cm 2 ) or more is more preferable.

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Abstract

Provided is a thermometry resistor with which it is possible to measure a temperature in a wide temperature range from room temperature to extreme low temperature without being significantly affected by magnetic fields. Chromium nitride, which is antiferromagnetic at temperatures of at least 100K or less, is used as a material of a thermometry resistor. A thermometer (10) has a chromium nitride film (2), which is antiferromagnetic at temperatures of at least 100K or less, disposed upon a substrate (1).

Description

測温抵抗体及び温度計Resistance thermometer and thermometer
　本発明は、測温抵抗体及びそれを用いた極低温用の温度計に関する。 The present invention relates to a resistance temperature detector and a cryogenic thermometer using the same.
　従来から極低温領域における基礎研究及び実用化研究が進められている。中でも、高磁場下での各種超電導材料の物性研究や超電導材料を用いた機器類の開発等が盛んに行われている。このような研究・開発においては、磁場の影響を受けることなく、極低温の温度を正確に測定することが必要となる。 Conventionally, basic research and practical application research in the cryogenic region have been promoted. In particular, research on the physical properties of various superconducting materials under high magnetic fields and the development of devices using superconducting materials are being actively conducted. In such research and development, it is necessary to accurately measure the cryogenic temperature without being affected by the magnetic field.
　一方、極低温・高磁場の条件下で使用する温度計としては、以下のような特性を有するものが求められている。
（１）磁場による攪乱が小さい。
（２）感度(以下、感度は絶対値をとるものとする）が高い。
（３）サーマルサイクルに対する安定性に優れている。
（４）測温領域が広い。
（５）熱伝導率が高い材料により構成されている。
（６）熱容量が小さい。
（７）安価に作製できる。 On the other hand, a thermometer having the following characteristics is required as a thermometer used under conditions of extremely low temperature and high magnetic field.
(1) The disturbance due to the magnetic field is small.
(2) Sensitivity (hereinafter, the sensitivity is assumed to be an absolute value) is high.
(3) Excellent stability against thermal cycle.
(4) Wide temperature measurement area.
(5) It is made of a material having high thermal conductivity.
(6) The heat capacity is small.
(7) It can be manufactured at low cost.
　このような特性を有する温度計としては、基板上に厚さ５０～１０００ｎｍの窒化クロム薄膜を設け、その窒化クロム薄膜中の窒素含有量を４０～６０原子％とした測温抵抗体を備えた温度計（例えば、特許文献１参照）が知られている。この種の温度計では、上記の特性をバランスよく有し、特にサーマルサイクルに対する安定性に優れると共に、広い磁場範囲における温度測定が可能となる。
　尚、上記の特許文献１における窒化クロムは、特許文献１に記載の実施例１を追試した後述の比較例（図３）に示すように、Ｃｒ２Ｎであることが確認されており、特許文献１に記載の窒化クロムは、Ｃｒ２Ｎにおいて過剰な窒素を含むものと推測される。 As a thermometer having such characteristics, a resistance temperature detector was provided in which a chromium nitride thin film having a thickness of 50 to 1000 nm was provided on a substrate, and the nitrogen content in the chromium nitride thin film was 40 to 60 atomic%. A thermometer (see, for example, Patent Document 1) is known. This type of thermometer has the above-mentioned characteristics in a well-balanced manner, and is particularly excellent in stability against a thermal cycle, and can measure temperature in a wide magnetic field range.
Note that the chromium nitride in Patent Document 1 is confirmed to be Cr 2 N, as shown in a comparative example (FIG. 3) described later in which Example 1 described in Patent Document 1 was added. The chromium nitride described in Document 1 is presumed to contain excess nitrogen in Cr 2 N.
特開２００１－１１０６０６号公報JP 2001-110606 A
　上記の通り前記従来の温度計は、極低温・高磁場の条件下において、磁場の影響を受けることなく、温度を測定することができる。しかし、近年では、さらに磁場の影響を受け難く、より広い温度領域を測定できる温度計が求められるようになってきた。 As described above, the conventional thermometer can measure the temperature without being affected by the magnetic field under the conditions of extremely low temperature and high magnetic field. However, in recent years, there has been a demand for a thermometer that is less affected by a magnetic field and can measure a wider temperature range.
　本発明は上記問題に鑑み案出されたものであり、磁場の影響を受け難く、室温から極低温に亘る広い温度領域での温度測定を可能とする測温抵抗体及び温度計を提供することを目的とする。 The present invention has been devised in view of the above problems, and provides a resistance temperature detector and a thermometer that are not easily affected by a magnetic field and enable temperature measurement in a wide temperature range from room temperature to extremely low temperature. With the goal.
　上記目的を達成するための本発明に係る測温抵抗体の特徴構成は、少なくとも１００Ｋ以下で反強磁性となる窒化クロムを材料とした点にある。 The characteristic structure of the resistance temperature detector according to the present invention for achieving the above object is that chromium nitride which becomes antiferromagnetic at least 100K or less is used as a material.
　本発明者らは、反強磁性半導体の磁気抵抗効果が小さいことに着目し、鋭意検討した結果、反強磁性半導体を測温抵抗体の材料として用いることにより、磁気抵抗効果の温度依存性が小さくなることを見出し、本発明に至った。
　一方、窒化クロムには、後述の実施例２（図４）で示すように、２２０Ｋ付近で反強磁性に転位し始め、１００Ｋ以下の低温域において反強磁性となるものがある。
　したがって、本構成のように、測温抵抗体の材料として、磁気抵抗効果の影響が大きくなる低温域で反強磁性となる窒化クロムを用いることにより、磁場の影響を受け難く、室温から極低温に亘る広い温度領域での温度測定が可能となる。
　尚、反強磁性となる窒化クロムとして、後述の実施例１（図２）では、ＣｒＮであることを確認している。 The present inventors paid attention to the fact that the magnetoresistive effect of the antiferromagnetic semiconductor is small, and as a result of intensive studies, the temperature dependence of the magnetoresistive effect is reduced by using the antiferromagnetic semiconductor as a material for the resistance temperature detector. As a result, the present invention has been found.
On the other hand, as shown in Example 2 (FIG. 4) described later, some chromium nitrides begin to dislocation to antiferromagnetism at around 220K and become antiferromagnetic at a low temperature range of 100K or less.
Therefore, by using chromium nitride, which is antiferromagnetic in the low temperature range where the magnetoresistive effect is large, as in this configuration, it is hardly affected by the magnetic field by using chromium nitride that is antiferromagnetic in the low temperature range. It is possible to measure the temperature over a wide temperature range.
In addition, it confirmed that it was CrN in Example 1 (FIG. 2) mentioned later as chromium nitride used as antiferromagnetism.
　窒化クロムは安価に作製することができるため、測温抵抗体の製造コストを低くすることができる。また、窒化クロムは水や湿気の影響を受け難いため、測温抵抗体を使用できる条件が広がる。
　さらに、窒化クロムは、二元系であり、安定な構造であるため、個々の特性が揃った（互換性のある）測温抵抗体を作製することができる。このため、個体間の温度特性が揃った温度計を大量に供給することができる。 Since chromium nitride can be manufactured at low cost, the manufacturing cost of the resistance temperature detector can be reduced. In addition, since chromium nitride is not easily affected by water or moisture, the conditions under which a resistance temperature detector can be used are expanded.
Further, since chromium nitride is a binary system and has a stable structure, a resistance temperature detector having the same individual characteristics (compatible) can be manufactured. For this reason, a large number of thermometers with uniform temperature characteristics can be supplied.
　本発明に係る温度計の特徴構成は、少なくとも１００Ｋ以下で反強磁性となる窒化クロムの膜を、基板の上に設けた点にある。 The characteristic configuration of the thermometer according to the present invention is that a chromium nitride film which becomes antiferromagnetic at least 100K or less is provided on a substrate.
　本構成によれば、磁場の影響を受け難く、室温から極低温に亘る広い温度領域を測定できる温度計を提供することができる。 This configuration can provide a thermometer that is not easily affected by a magnetic field and that can measure a wide temperature range from room temperature to extremely low temperatures.
　本発明に係る温度計において、前記窒化クロムの膜は、前記窒化クロムの結晶成長が抑制された薄膜で構成され、結晶粒径が１５ｎｍ以下であることが好ましい。 In the thermometer according to the present invention, the chromium nitride film is preferably formed of a thin film in which crystal growth of the chromium nitride is suppressed, and the crystal grain size is preferably 15 nm or less.
　本構成によれば、窒化クロムの膜は、窒化クロムの結晶成長を抑制し、結晶粒径が１５ｎｍ以下となるように構成してあるため、窒化クロムの磁気抵抗効果を小さくすることができる。 According to this configuration, the chromium nitride film suppresses crystal growth of chromium nitride and has a crystal grain size of 15 nm or less, so that the magnetoresistance effect of chromium nitride can be reduced.
　本発明に係る温度計において、前記基板は、熱膨張係数が１×１０－６～５×１０－６／Ｋの範囲にあることが好ましい。 In the thermometer according to the present invention, the substrate preferably has a thermal expansion coefficient in the range of 1 × 10 −6 to 5 × 10 −6 / K.
　本構成によれば、基板と窒化クロムとの熱膨張係数の差が小さくなるため、サーマルサイクルの安定性をより向上させることができる。 According to this configuration, since the difference in thermal expansion coefficient between the substrate and chromium nitride is reduced, the stability of the thermal cycle can be further improved.
　本発明に係る温度計において、前記基板は、シリコン基板であることが好ましく、電気抵抗率が７０００Ωｃｍ以上であることが好ましい。 In the thermometer according to the present invention, the substrate is preferably a silicon substrate, and an electrical resistivity is preferably 7000 Ωcm or more.
　電気抵抗率が７０００Ωｃｍ以上であれば、低温域においてはより電気抵抗率が高くなるため、温度計の基板として適用できる。このため、入手が容易な高抵抗シリコン基板を用いることができる。 If the electrical resistivity is 7000 Ωcm or more, the electrical resistivity becomes higher in the low temperature range, and therefore it can be applied as a thermometer substrate. For this reason, it is possible to use a high-resistance silicon substrate that is easily available.
　本発明に係る温度計において、前記窒化クロムの膜の上に、一対の電極を所定の電極間距離で配置し、特定の温度域における測定感度を高めることが好ましい。 In the thermometer according to the present invention, it is preferable that a pair of electrodes are arranged at a predetermined inter-electrode distance on the chromium nitride film to increase measurement sensitivity in a specific temperature range.
　本構成によれば、窒化クロムは、後述の実施例３（図５）に示すように、１Ｋ～３００Ｋに亘って絶対感度Ｓａ（Ｓａ＝｜ＴｄＲ／ＲｄＴ｜、Ｔは絶対温度、Ｒは電気抵抗）が１付近にあるため、一対の電極を所定の電極間距離に配置し、微分感度｜ｄＲ／ｄＴ｜（Ω／Ｋ）を設定することにより、特定の温度域における測定感度を高めることができる。 According to this configuration, as shown in Example 3 (FIG. 5) to be described later, chromium nitride has an absolute sensitivity Sa (Sa = | TdR / RdT |) where 1K to 300K, T is absolute temperature, and R is electrical (Resistance) is in the vicinity of 1, so that a pair of electrodes are arranged at a predetermined inter-electrode distance and the differential sensitivity | dR / dT | (Ω / K) is set to increase the measurement sensitivity in a specific temperature range. Can do.
　本発明に係る温度計の設定方法の特徴構成は、基板の上に、少なくとも１００Ｋ以下で反強磁性となる窒化クロムの膜を設けた温度計において、前記窒化クロム膜の上に設ける一対の電極の電極間距離を変更することにより、測定感度の高い温度域を設定する点にある。 A characteristic configuration of the thermometer setting method according to the present invention is a thermometer in which a chromium nitride film that becomes antiferromagnetic at least 100K or less is provided on a substrate, and a pair of electrodes provided on the chromium nitride film By changing the distance between the electrodes, a temperature range with high measurement sensitivity is set.
　本構成によれば、窒化クロムは、後述の実施例３（図５）に示すように、１Ｋ～３００Ｋに亘って絶対感度Ｓａが１付近にあるため、窒化クロムの膜の上に設ける一対の電極の電極間距離を変更し、微分感度｜ｄＲ／ｄＴ｜（Ω／Ｋ）を設定することにより、測定感度の高い温度域を適宜設定することができる。 According to this configuration, as shown in Example 3 (FIG. 5) to be described later, since the absolute sensitivity Sa is in the vicinity of 1 over 1K to 300K, chromium nitride has a pair of chromium nitride films provided on the chromium nitride film. By changing the distance between the electrodes and setting the differential sensitivity | dR / dT | (Ω / K), a temperature range with high measurement sensitivity can be set as appropriate.
　本発明に係る温度計の製造方法の特徴構成は、製膜室内に、基板と金属クロムとを配置し、窒素の割合が８０％以上の雰囲気となるように窒素または窒素と希ガスとの混合ガスを導入し、金属クロムと窒素とを反応させて前記基板上に少なくとも１００Ｋ以下で反強磁性となる窒化クロムの膜を形成する点にある。 The thermometer manufacturing method according to the present invention is characterized in that a substrate and metallic chromium are arranged in a film forming chamber, and nitrogen or a mixture of nitrogen and a rare gas so that the atmosphere has a nitrogen ratio of 80% or more. A gas is introduced to react metal chromium and nitrogen to form a chromium nitride film that becomes antiferromagnetic at least 100 K or less on the substrate.
　本構成によれば、少なくとも１００Ｋ以下で反強磁性となる窒化クロムの膜を、基板の上に形成することができるため、磁場の影響を受け難く、室温から極低温に亘る広い温度領域を測定できる温度計を作製することができる。 According to this configuration, a chromium nitride film that becomes antiferromagnetic at least at 100K or less can be formed on a substrate, so that it is difficult to be affected by a magnetic field, and a wide temperature range from room temperature to extremely low temperature is measured. A thermometer can be made.
　本発明に係る温度計の製造方法において、金属クロムと窒素とを反応させる際に、前記基板を１００℃以下に保つことにより、窒化クロムの結晶粒成長を抑制し、粒径を小さくすることが好ましい。 In the thermometer manufacturing method according to the present invention, when the metal chromium and nitrogen are reacted, the crystal growth of chromium nitride can be suppressed and the particle size can be reduced by keeping the substrate at 100 ° C. or lower. preferable.
　本構成によれば、金属クロムと窒素とを反応させる際に、基板を１００℃以下に保つことにより、基板上に形成される窒化クロムの結晶粒径を小さくすることができる。 According to this configuration, when the metal chromium and nitrogen are reacted, the crystal grain size of chromium nitride formed on the substrate can be reduced by keeping the substrate at 100 ° C. or lower.
本発明に係る温度計の概略図である。It is the schematic of the thermometer which concerns on this invention. 実施例１で作製した窒化クロムのＸ線回折法による結晶構造解析結果を示すグラフである。2 is a graph showing the results of crystal structure analysis of chromium nitride produced in Example 1 by X-ray diffraction. 比較例で作製した窒化クロムのＸ線回折法による結晶構造解析結果を示すグラフである。It is a graph which shows the crystal structure analysis result by the X-ray diffraction method of the chromium nitride produced by the comparative example. 実施例１で作製した窒化クロムが反強磁性に転位することを示すグラフである。It is a graph which shows that the chromium nitride produced in Example 1 transfers to antiferromagnetism. 実施例３で作製した温度計の温度・抵抗特性、及び絶対感度の温度依存性を示すグラフである。It is a graph which shows the temperature and resistance characteristic of the thermometer produced in Example 3, and the temperature dependence of absolute sensitivity. 実施例３で作製した温度計を４Ｋと３００Ｋの間を２７回サイクルさせたときの、電気抵抗の変化を示すグラフである。It is a graph which shows the change of an electrical resistance when the thermometer produced in Example 3 is made to cycle 27 times between 4K and 300K. 実施例３で作製した温度計を４Ｋと３００Ｋの間を２７回サイクルさせたときの、４Ｋでの電気抵抗の測定結果を示すグラフである。It is a graph which shows the measurement result of the electrical resistance in 4K when the thermometer produced in Example 3 was cycled 27 times between 4K and 300K. 実施例３で作製した温度計とは基板のみをＳｉＯ２基板に変えた温度計を４Ｋと３００Ｋの間を２回サイクルさせたときの、電気抵抗値の変化を示すグラフである。The thermometer produced in Example 3 is a graph showing a change in electric resistance value when a thermometer in which only the substrate is changed to a SiO 2 substrate is cycled twice between 4K and 300K. 実施例３で作製した温度計を、４Ｋ及び２Ｋで、９Ｔまで磁場を変化させたときの温度誤差の変化を示すグラフである。It is a graph which shows the change of the temperature error when the thermometer produced in Example 3 is changed to 9T at 4K and 2K. 反応性ＲＦマグネトロンスパッタリング法により窒素分圧を変えて作製した窒化クロム薄膜の電気抵抗値の変化を示すグラフである。It is a graph which shows the change of the electrical resistance value of the chromium nitride thin film produced by changing nitrogen partial pressure by the reactive RF magnetron sputtering method. 反応性ＤＣマグネトロンスパッタリング法により窒素分圧を変えて作製した窒化クロム薄膜の電気抵抗値の変化を示すグラフである。It is a graph which shows the change of the electrical resistance value of the chromium nitride thin film produced by changing nitrogen partial pressure by the reactive DC magnetron sputtering method. 反応性ＲＦマグネトロンスパッタリング法により窒素分圧を変えて作製した窒化クロム薄膜における電気抵抗値の温度依存性を示すグラフである。It is a graph which shows the temperature dependence of the electrical resistance value in the chromium nitride thin film produced by changing nitrogen partial pressure by the reactive RF magnetron sputtering method. 反応性ＲＦマグネトロンスパッタリング法により製膜電圧を変えて作製した窒化クロム薄膜の電気抵抗値の温度依存性を示すグラフである。It is a graph which shows the temperature dependence of the electrical resistance value of the chromium nitride thin film produced by changing film-forming voltage by the reactive RF magnetron sputtering method.
　本発明に係る測温抵抗体は、少なくとも１００Ｋ以下で反強磁性となる窒化クロムを材料とする。本発明に係る温度計は、少なくとも１００Ｋ以下で反強磁性となる窒化クロムの膜を基板に設ける。本発明によれば、磁場の影響を受けることなく、室温から極低温（例えば、３００Ｋ～１Ｋ程度）までの幅広い温度範囲の測定が可能となる。また、窒化クロムは、安定な構造であり、安価に作製することができるため、個々の特性が揃った（互換性のある）温度計を、低い製造コストで、大量に供給することができる。さらに、窒化クロムは水や湿気の影響を受け難いため、温度計の汎用性が高まる。例えば、図１に示すように、１ｍｍ角の基板１上に窒化クロムの膜２を設け、その上に電極３，４を形成することにより、小型で低熱容量であり、安価に量産可能な温度計１０として用いることが可能である。 The resistance temperature detector according to the present invention is made of chromium nitride that becomes antiferromagnetic at least 100K or less. The thermometer according to the present invention is provided with a chromium nitride film that becomes antiferromagnetic at least 100K or less on a substrate. According to the present invention, measurement in a wide temperature range from room temperature to extremely low temperature (for example, about 300 K to 1 K) can be performed without being affected by a magnetic field. In addition, since chromium nitride has a stable structure and can be manufactured at low cost, it is possible to supply a large number of thermometers with uniform characteristics (compatible) at a low manufacturing cost. Furthermore, since chromium nitride is not easily affected by water and moisture, the versatility of the thermometer is enhanced. For example, as shown in FIG. 1, by providing a chromium nitride film 2 on a 1 mm square substrate 1 and forming electrodes 3 and 4 thereon, a temperature that is small and has a low heat capacity and can be mass-produced inexpensively. It can be used as a total of ten.
　一般に、金属は温度の低下とともに電気抵抗が減少するため、高感度で極低温から室温までの温度計を提供することはできない。しかし、窒化物は過剰なあるいは過不足な窒素含有物薄膜を作製することで結晶構造を壊し、内在する電子を局在化させることで温度計の機能を発現させることができる。従来の温度計では、金属窒化物に過剰な窒素あるいは窒素を著しく過不足状態にして、金属電子を局在状態にすることで、温度の低下とともに電気抵抗を増加させることを達成し、極低温状態まで高感度で測定できるようにしたものが知られている。すなわち、金属薄膜を窒素により結晶構造を乱し温度計の機能を発現させたものである。このような温度計は優れた特性を示すが、構造の乱れ方は様々であるため、温度計としての個々の製品間のばらつきをなくすことは困難であった。これに対し、反強磁性の窒化クロムを用いれば、極低温の領域において、高感度で温度を測定することができるだけでなく、安定に存在する結晶構造（例えば、ＣｒＮ（Ｃｒ:Ｎ=１:１））を有するため、温度計としたときの個体間のばらつきを極力なくすことが可能となる。 Generally, since the electric resistance of metal decreases with a decrease in temperature, it is not possible to provide a thermometer with high sensitivity from cryogenic temperature to room temperature. However, the nitride can break down the crystal structure by producing an excessive or insufficient nitrogen-containing thin film, and the function of the thermometer can be expressed by localizing the underlying electrons. The conventional thermometer achieves an increase in electrical resistance as the temperature decreases by putting excessive nitrogen or nitrogen in the metal nitride in a significantly excessive or insufficient state and making the metal electrons localized, thereby reducing the temperature. A device that can measure a state with high sensitivity is known. That is, the crystal structure of the metal thin film is disturbed by nitrogen, and the function of the thermometer is expressed. Although such a thermometer exhibits excellent characteristics, it is difficult to eliminate variations among individual products as a thermometer because the structure is disturbed in various ways. On the other hand, when antiferromagnetic chromium nitride is used, temperature can be measured with high sensitivity in an extremely low temperature region, and a stable crystal structure (for example, CrN (Cr: N = 1: 1)), it is possible to minimize variations among individuals when a thermometer is used.
　窒化クロムは、少なくとも１００Ｋ以下で反強磁性となるものを用いる。窒化クロムは、１００Ｋより高い温度においても反強磁性となっていることは何ら問題なく、むしろ好ましいが、温度が高い場合には磁気抵抗効果の影響が小さくなるため、少なくとも１００Ｋ以下で反強磁性となれば、１０Ｔのような高磁場下においても室温から極低温に亘る広い温度領域での温度測定が可能となる。例えば、後述の実施例で用いている窒化クロムは、図２に示すように２２０Ｋ付近で反強磁性に転位し始め、１００Ｋ以下の低温域においては確実に反強磁性となっている。 As the chromium nitride, one that becomes antiferromagnetic at least 100K or less is used. It is preferable that chromium nitride is antiferromagnetic even at a temperature higher than 100K, but it is preferable. However, when the temperature is high, the influence of the magnetoresistive effect is reduced, and therefore antiferromagnetic at least 100K or less. Then, temperature measurement in a wide temperature range from room temperature to extremely low temperature is possible even under a high magnetic field such as 10T. For example, as shown in FIG. 2, the chromium nitride used in the examples described later starts to dislocation to antiferromagnetism at around 220K, and is reliably antiferromagnetic at a low temperature range of 100K or less.
　窒化クロムの膜は、窒化クロムの結晶成長が抑制された薄膜で構成されることが好ましい。また、窒化クロムの結晶粒径は、１５ｎｍ以下であることが好ましく、１０ｎｍ以下であることがより好ましく、５ｎｍ以下であることがさらに好ましい。 The chromium nitride film is preferably composed of a thin film in which the crystal growth of chromium nitride is suppressed. The crystal grain size of chromium nitride is preferably 15 nm or less, more preferably 10 nm or less, and further preferably 5 nm or less.
　本発明において、窒化クロムの膜を設ける基板は、特に限定されないが、熱膨張係数が１×１０－６～５×１０－６／Ｋの範囲にあるものが好ましい。この場合、基板と窒化クロムとの熱膨張係数の差が小さくなるため、サーマルサイクルの安定性をより向上させることができる。このような基板としては、シリコンウェハ、サファイア等が例示される。中でもシリコンウェハが好ましく、特に電気抵抗率が７０００Ωｃｍ以上のシリコンウェハが好ましい。すなわち、このような基板は、入手容易であるだけでなく、厚みが５００μｍの基板ベースで、室温における電気抵抗率が７０００Ωｃｍ以上であれば、低温になるほど電気抵抗率が高くなるため、絶縁基板でなくても本発明に係る温度計の基板として好ましく適用できる。 In the present invention, the substrate on which the chromium nitride film is provided is not particularly limited, but preferably has a thermal expansion coefficient in the range of 1 × 10 −6 to 5 × 10 −6 / K. In this case, since the difference in thermal expansion coefficient between the substrate and chromium nitride is reduced, the stability of the thermal cycle can be further improved. Examples of such a substrate include a silicon wafer and sapphire. Among these, a silicon wafer is preferable, and a silicon wafer having an electrical resistivity of 7000 Ωcm or more is particularly preferable. That is, such a substrate is not only easily available, but also has a substrate base with a thickness of 500 μm, and if the electrical resistivity at room temperature is 7000 Ωcm or more, the electrical resistivity increases as the temperature decreases. Even if not, it can be preferably applied as a substrate of the thermometer according to the present invention.
　本発明に係る温度計は、反強磁性の窒化クロムを材料として従来公知の装置により作製できる。作製方法は特に限定されないが、例えば、以下の方法により作製することができる。 The thermometer according to the present invention can be manufactured by a conventionally known apparatus using antiferromagnetic chromium nitride as a material. Although the manufacturing method is not particularly limited, for example, it can be manufactured by the following method.
　まず、基板を常法に従って洗浄する。基板としてシリコンウェハ等を使用する場合には、そのまま用いることができるが、常法に従って、その表面に電気絶縁を保ち得る程度の厚さのＳｉＯ２層あるいは他の材料を用いた電気絶縁層(例えば、Ａｌ２Ｏ３、ＺｒＯ２、Ｓｉ３Ｎ４等)を予め形成させておいてもよい。次いで、その基板上にスパッタリング法(例えば、反応性ＲＦマグネトロンスパッタリング法等)により、窒化クロム（ＣｒＮ）薄膜を形成させる。 First, the substrate is cleaned according to a conventional method. When a silicon wafer or the like is used as a substrate, it can be used as it is. However, according to a conventional method, an SiO 2 layer having a thickness that can keep electric insulation on the surface or an electric insulating layer using another material ( For example, Al 2 O 3 , ZrO 2 , Si 3 N 4 or the like) may be formed in advance. Next, a chromium nitride (CrN) thin film is formed on the substrate by sputtering (for example, reactive RF magnetron sputtering).
　具体的には、例えば、公知のマグネトロンスパッタリング装置を用い、基板とＣｒターゲットをセットした製膜室の内部を、１．３×１０－３Ｐａ以下、より好ましくは７×１０－５Ｐａ程度まで排気して真空度を上昇させる。その後、内圧が１Ｐａ程度となるようにＡｒを製膜室に導入し、Ｃｒターゲットの表面を浄化するためのプレスパッタリングを行う。 Specifically, for example, using a known magnetron sputtering apparatus, the inside of the film forming chamber in which the substrate and the Cr target are set is set to 1.3 × 10 −3 Pa or less, more preferably to about 7 × 10 −5 Pa. Evacuate to increase vacuum. Thereafter, Ar is introduced into the film forming chamber so that the internal pressure becomes about 1 Pa, and pre-sputtering for purifying the surface of the Cr target is performed.
　プレスパッタリングを行った後は、製膜室の内部を再度上記の真空度と同程度の真空度となるまで排気し、Ｎ２を導入する。Ｎ２の流量は、例えば、２０ ｓｃｃｍ程度である。また、必要に応じてＮ２をＡｒで希釈してもよく、その場合には、全流量を３０ ｓｃｃｍ程度とすることが好ましい。この時のＮ２の分圧は、１Ｐａ ８０％～１００％(Ｎ２のみ)が好ましく、１Ｐａ １００％が特に好ましい。 After performing the pre-sputtering, the inside of the film forming chamber is evacuated again until the degree of vacuum is the same as the above degree of vacuum, and N 2 is introduced. The flow rate of N 2 is, for example, about 20 sccm. Further, if necessary, N 2 may be diluted with Ar. In that case, the total flow rate is preferably about 30 sccm. The partial pressure of N 2 at this time is preferably 1 Pa 80% to 100% (N 2 only), particularly preferably 1 Pa 100%.
　製膜室において、上記の雰囲気状態が得られた時点で、基板の温度を室温（２５℃程度）～２００℃程度に保持し、４～８Ｗ／ｃｍ２程度の製膜電力で、厚さ２５～１０００ｎｍ程度の窒化クロム薄膜が形成されるまで、スパッタリング操作を行う。尚、基板の温度は、室温～２００℃の範囲に限定されないが、１００℃より低くなり過ぎると基板に吸着した水分の影響が出始め再現性、密着性等に悪影響を与える恐れがある。また、基板温度はその膜にとって最高経験温度となる。温度計として使用する場合、水分を蒸発させるために１００℃程度に使用装置全体を加熱する場合があるが、このとき最高経験温度を超えると温度計の特性が変化する可能性が有る。一方基板温度が２００℃を超えてさらに高くなり過ぎると分解し易くなる。このため、基板の温度は、２００℃以下が好ましく、１００℃以下がより好ましい。
　また、基板上に形成される窒化クロム薄膜の結晶粒成長を制御する観点からは、ＣｒとＮ２とを反応させる際に、基板を１００℃以下に保持することにより、結晶粒成長を抑えて、窒化クロムの結晶粒径を小さくすることができる。 In the film forming chamber, when the above atmospheric condition is obtained, the substrate temperature is maintained at room temperature (about 25 ° C.) to about 200 ° C., and the film forming power is about 4 to 8 W / cm 2 to obtain a thickness of 25 A sputtering operation is performed until a chromium nitride thin film of about ˜1000 nm is formed. The temperature of the substrate is not limited to the range of room temperature to 200 ° C., but if it becomes lower than 100 ° C., the influence of moisture adsorbed on the substrate starts to appear, and the reproducibility and adhesion may be adversely affected. The substrate temperature is the highest experience temperature for the film. When used as a thermometer, the entire device used may be heated to about 100 ° C. in order to evaporate water, but if the maximum experience temperature is exceeded at this time, the characteristics of the thermometer may change. On the other hand, when the substrate temperature exceeds 200 ° C. and becomes too high, it becomes easy to decompose. For this reason, the temperature of the substrate is preferably 200 ° C. or less, and more preferably 100 ° C. or less.
In addition, from the viewpoint of controlling the crystal grain growth of the chromium nitride thin film formed on the substrate, the crystal grain growth is suppressed by maintaining the substrate at 100 ° C. or lower when reacting Cr and N 2. The crystal grain size of chromium nitride can be reduced.
　基板上にＣｒＮ薄膜が形成された後は、例えば、真空蒸着法やスパッタ法により、ＣｒＮ薄膜に電極を形成することで、本発明に係る温度計が得られる。電極材料としては、公知のものが使用でき、Ａｇ、Ｃｒ、Ａｕ、Ｃｕ、Ａｌ、Ｖ、Ｉｎ、Ｐｔ、Ｒｈ、Ｔｉ、Ｎｂ等が例示され、特に限定されないが、Ｎｂは、シリコンウェハやＣｒＮ薄膜となじみが良く、オーミックコンタクトが容易に実現すると共に、サーマルサイクル安定性が向上するため、特に好ましい。 After the CrN thin film is formed on the substrate, the thermometer according to the present invention can be obtained by forming electrodes on the CrN thin film by, for example, vacuum deposition or sputtering. As the electrode material, known materials can be used, and examples thereof include Ag, Cr, Au, Cu, Al, V, In, Pt, Rh, Ti, and Nb. Although not particularly limited, Nb is a silicon wafer or CrN. This is particularly preferable because it is well-suited to a thin film, easily realizes ohmic contact, and improves thermal cycle stability.
　ＣｒＮ薄膜の上に電極を形成する際の電極間距離は、その距離によって電気抵抗値が変化するため、測定感度を高めたい温度域に応じて適宜設定することができる。すなわち、温度計の電気抵抗値としては、１ｋΩあたりが最も測定し易いため、所望の温度域の抵抗値を１ｋΩあたりとなるように電極間距離を設定することが好ましい。 The distance between the electrodes when the electrodes are formed on the CrN thin film can be set as appropriate according to the temperature range in which the measurement sensitivity is desired to be increased because the electric resistance value varies depending on the distance. That is, as the electric resistance value of the thermometer, it is easy to measure around 1 kΩ, and therefore it is preferable to set the inter-electrode distance so that the resistance value in a desired temperature range is around 1 kΩ.
　以下に、本発明を用いた実施例を示し、本発明をより詳細に説明するが、本発明はこれらの実施例に限定されるものではない。 Hereinafter, examples using the present invention will be shown and the present invention will be described in more detail. However, the present invention is not limited to these examples.
（実施例１）
　反応性ＲＦマグネトロンスパッタリング法により、基板上に窒化クロム薄膜を形成し、窒化クロム薄膜のＸ線回折法による結晶構造解析を行った。その結果を図２に示した。
　スパッタリングは、以下の条件で行った。
　基板：高抵抗Siウエハー（公称１０ｋΩｃｍ以上、実測２０ｋΩｃｍ）、直径１００ｍｍ、厚み５００μｍ
　基板温度：スパッタ中に基板がプラズマで加熱されるため特にヒータ加熱していないが、～１００℃になっている。
　真空度：５×１０－４Ｐａ
　ターゲット：金属Ｃｒ(純度９９．９９％）
　スパッタガス及び反応性ガス：Ｎ２ガス
　ガス流量：４０ｓｃｃｍ
　スパッタ圧：１Ｐａ
　製膜電力（投入高周波電力）：７Ｗ／ｃｍ２
　窒化クロム薄膜厚み：３００ｎｍ
　Ｘ線回折は、ＣｕＫα線を用いた２θ-θ法で行った。 Example 1
A chromium nitride thin film was formed on the substrate by reactive RF magnetron sputtering, and the crystal structure of the chromium nitride thin film was analyzed by X-ray diffraction. The results are shown in FIG.
Sputtering was performed under the following conditions.
Substrate: High resistance Si wafer (nominal 10 kΩcm or more, actual measurement 20 kΩcm), diameter 100 mm, thickness 500 μm
Substrate temperature: Since the substrate is heated by plasma during sputtering, the heater is not heated, but it is ˜100 ° C.
Degree of vacuum: 5 × 10 −4 Pa
Target: Metal Cr (Purity 99.99%)
Sputtering gas and reactive gas: N 2 gas Gas flow rate: 40 sccm
Sputtering pressure: 1Pa
Film-forming power (input high frequency power): 7 W / cm 2
Chromium nitride thin film thickness: 300nm
X-ray diffraction was performed by the 2θ-θ method using CuKα rays.
（比較例：特開２００１－１１０６０６号公報の実施例１の追試）
　反応性ＤＣマグネトロンスパッタリング法により、以下の条件で基板上に窒化クロム薄膜を形成し、窒化クロム薄膜のＸ線回折法による結晶構造解析を行い、その結果を図３に示した。
　基板：ＳｉＯ2（１０ｍｍ角、厚み０．３ｍｍ）
　基板温度：３００℃
　真空度：５×１０－４Ｐａ
　ターゲット：金属Ｃｒ(直径１００ｍｍ×厚さ５ｍｍ)
　スパッタガス：Ａｒ
　反応性ガス：窒素
　ガス流量：６ｓｃｃｍ
　Ｎ２／（Ａｒ＋Ｎ２)＝５０％
　製膜電力：２００Ｗ
　基板温度：３００℃
　窒化クロム薄膜厚み：２５０ｎｍ (Comparative example: Additional test of Example 1 of JP-A-2001-110606)
A chromium nitride thin film was formed on the substrate under the following conditions by the reactive DC magnetron sputtering method, and the crystal structure analysis of the chromium nitride thin film by the X-ray diffraction method was performed. The results are shown in FIG.
Substrate: SiO 2 (10 mm square, thickness 0.3 mm)
Substrate temperature: 300 ° C
Degree of vacuum: 5 × 10 −4 Pa
Target: Metal Cr (diameter 100mm x thickness 5mm)
Sputtering gas: Ar
Reactive gas: Nitrogen Gas flow rate: 6sccm
N 2 / (Ar + N 2 ) = 50%
Film forming power: 200W
Substrate temperature: 300 ° C
Chromium nitride thin film thickness: 250nm
　図２から、実施例１で作製した窒化クロム薄膜はＣｒＮであることが分かった。また、図２及び３から、実施例１で作製した窒化クロム薄膜と比較例で作製した窒化クロム薄膜とでは、結晶構造（Ｘ線回折におけるピークの位置）が異なっており、比較例で作製した窒化クロム薄膜はＣｒ２Ｎであることが分かった。 From FIG. 2, it was found that the chromium nitride thin film produced in Example 1 was CrN. 2 and 3, the chromium nitride thin film produced in Example 1 and the chromium nitride thin film produced in the comparative example have different crystal structures (peak positions in X-ray diffraction) and were produced in the comparative example. The chromium nitride thin film was found to be Cr 2 N.
　また、図２から、ＣｒＮ（１１１）、ＣｒＮ（２００）のピークの半値幅を求めると、それぞれ３．６°、４°となる。これらの値に基づき、デバイシェラーの式から窒化クロムの結晶粒径を計算すると、それぞれ２．１ｎｍ、２．３ｎｍであった。
　デバイシェラーの式：Ｄ＝Ｋ・λ／Ｂ・ｃｏｓθ
　Ｄ：結晶粒径、λ：測定に供した波長（Ｘ線のＣｕＫα線：０．１５４ｎｍ）、Ｂ：半値幅、θ：回折角、Ｋ：比例定数で０．９と仮定 Further, when the half-value widths of the peaks of CrN (111) and CrN (200) are obtained from FIG. 2, they are 3.6 ° and 4 °, respectively. Based on these values, the crystal grain size of chromium nitride was calculated from the Debye-Scherrer equation and found to be 2.1 nm and 2.3 nm, respectively.
Debye-Scherrer equation: D = K · λ / B · cos θ
D: crystal grain size, λ: wavelength used for measurement (X-ray CuKα ray: 0.154 nm), B: half-width, θ: diffraction angle, K: proportional constant is assumed to be 0.9
（実施例２）
　実施例１で作製した窒化クロム薄膜の磁性の測定を、超伝導量子干渉計（ＳＱＵＩＤ）で行った。その結果、図４に示すように、窒化クロムは２２０Ｋ付近で反強磁性に転位し始め、１００Ｋ以下の低温域において反強磁性となっていることが確認できた。
（実施例３）
　実施例１で作製した窒化クロム薄膜の上に一対の電極（Ｎｂ）を形成し、温度計を作製した。この温度計の温度・抵抗特性、及び絶対感度の温度依存性について調べ、図５に示した。その結果、電極間距離を５０μｍとした窒化クロム薄膜の室温での電気抵抗は９Ω、絶対感度は０．９であり、室温での温度分解能は３ｍＫ以下であることが分かった。また、４Ｋでは、電気抵抗は１１００Ω、絶対感度は１．６であり、温度分解能は０．２ｍＫ以下であることが分かった。さらに、１Ｋでも絶対感度は２．５であり、外挿すると０．３Ｋ近傍まで使用可能であることが分かった。 (Example 2)
The magnetism of the chromium nitride thin film produced in Example 1 was measured with a superconducting quantum interferometer (SQUID). As a result, as shown in FIG. 4, it was confirmed that chromium nitride began to dislocation to antiferromagnetism at around 220K and became antiferromagnetic at a low temperature range of 100K or less.
(Example 3)
A pair of electrodes (Nb) was formed on the chromium nitride thin film produced in Example 1, and a thermometer was produced. The temperature / resistance characteristics of this thermometer and the temperature dependence of absolute sensitivity were examined and are shown in FIG. As a result, it was found that the chromium nitride thin film having a distance between electrodes of 50 μm had an electric resistance of 9Ω at room temperature, an absolute sensitivity of 0.9, and a temperature resolution at room temperature of 3 mK or less. At 4K, the electrical resistance was 1100Ω, the absolute sensitivity was 1.6, and the temperature resolution was 0.2 mK or less. Furthermore, the absolute sensitivity was 2.5 even at 1K, and it was found that it can be used up to about 0.3K when extrapolated.
　温度計は、電気抵抗値が１０００Ω付近が測定し易いため、上記の温度計の場合は、図３より４Ｋ付近に高い測定感度を有する。また、温度計を測定機器に設置する場合、測定機器の性能に応じて、求められる微分感度が変わるため、例えば、読み出しできる抵抗値の桁数が少ない場合などでは、大きな微分感度｜ｄＲ／ｄＴ｜（Ω／Ｋ）が必要となる。このため、温度計は、用途に応じて測定感度が高くなる温度域を設定することが好ましい。本実施例における温度計においては、窒化クロム薄膜の絶対温度が広い温度範囲に亘りほぼ１であるため、測温抵抗体の材料や製造条件を変えることなく、電極間距離を設定するだけで、電気抵抗値を一番測定しやすい値に調整することができ、かつ特性の温度域に適した微分感度に設定することができる。 Since the thermometer is easy to measure when the electrical resistance value is around 1000Ω, the above thermometer has a high measurement sensitivity around 4K from FIG. In addition, when a thermometer is installed in a measuring instrument, the required differential sensitivity changes depending on the performance of the measuring instrument. For example, when the number of digits of the resistance value that can be read is small, a large differential sensitivity | dR / dT | (Ω / K) is required. For this reason, it is preferable that the thermometer sets a temperature range in which the measurement sensitivity is high according to the application. In the thermometer in the present embodiment, the absolute temperature of the chromium nitride thin film is almost 1 over a wide temperature range, and therefore, only by setting the distance between the electrodes without changing the material and manufacturing conditions of the resistance temperature detector, The electrical resistance value can be adjusted to a value that is most easily measured, and the differential sensitivity suitable for the temperature range of the characteristic can be set.
　電気抵抗値Ｒ＝ρ０×電極間距離Ｌ／（電極の幅Ｗ×窒化クロムの膜厚ｄ）であるため、本実施例の場合、５０μｍ／（８００μｍ×３００ｎｍ）＝２×１０５（ｍ－１）であり、４Ｋ付近における測定感度が高くなっている。このため、この値を１０倍にすれば、１０Ｋ付近における測定感度が高くすることができ、１００倍にすると３００Ｋ付近における測定感度が高くすることができる。また、１／１０とすれば、４Ｋ以下のより低温側で測定しやすい抵抗値と微分感度に調整できる。 Since the electrical resistance value R = ρ 0 × interelectrode distance L / (electrode width W × chromium nitride film thickness d), in this example, 50 μm / (800 μm × 300 nm) = 2 × 10 5 (m -1 ), and the measurement sensitivity near 4K is high. Therefore, if this value is increased 10 times, the measurement sensitivity in the vicinity of 10K can be increased, and if it is increased 100 times, the measurement sensitivity in the vicinity of 300K can be increased. Moreover, if it is set to 1/10, it can adjust to the resistance value and differential sensitivity which are easy to measure on the low temperature side of 4K or less.
　本実施例の温度計において電極間距離を変えたものと、室温付近での精密温度計測に使用される白金製の測温抵抗体（３００Ｋで１００Ωのもの）を用いたものとの微分感度を調べ、表１に示した。これによれば、電極間距離を５００μｍに変えるだけで、室温の温度計測に特化された白金測温抵抗体と同じ感度の温度計を作製することができるが確認できた。尚、３００Ｋで１ｋΩの白金測温抵抗体と同程度のものを作るためには電極間距離を５ｍｍにすればよい。 The differential sensitivity between the thermometer of this example with the distance between the electrodes changed and the one using a platinum resistance thermometer (100Ω at 300K) used for precise temperature measurement near room temperature. The results are shown in Table 1. According to this, it was confirmed that a thermometer having the same sensitivity as that of a platinum resistance temperature detector specialized in temperature measurement at room temperature can be produced simply by changing the distance between the electrodes to 500 μm. In addition, in order to make the same level as a platinum resistance thermometer of 1 kΩ at 300K, the distance between the electrodes may be 5 mm.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
（実施例４）
　実施例３で作製した温度計を用い、４Ｋと３００Ｋの間を２７回サイクルさせて、電気抵抗の変化を調べ、図６に示した。また、そのときの４Ｋでの電気抵抗の測定結果を図７に示した。図６より、４Ｋでの標準偏差は０．９８Ωであり、変動係数から計算した温度シフトは２ｍＫ以下であった。測定に供した装置Quantum-Design社のＰＰＭＳ（Physical Properties Measurement System）の温度制御安定性は０．２％程度であり、サーマルサイクルによる抵抗変化は制御誤差内で変化していないことが分かった。
　また、実施例３で作製した温度計とは、基板のみを溶融石英（ＳｉＯ２）に変えたものについても同様に４Ｋと３００Ｋの間を２回サイクルさせて、電気抵抗の変化を調べた。その結果、図８に示すように、基板にＳｉを用いたものに比べ、サーマルサイクル安定性が低くなっていることが分かった。 Example 4
Using the thermometer produced in Example 3, the change in electrical resistance was investigated by cycling 27 times between 4K and 300K, and is shown in FIG. Moreover, the measurement result of the electrical resistance at 4K at that time is shown in FIG. From FIG. 6, the standard deviation at 4K was 0.98Ω, and the temperature shift calculated from the coefficient of variation was 2 mK or less. It was found that the temperature control stability of PPMS (Physical Properties Measurement System) manufactured by Quantum-Design, which was used for the measurement, was about 0.2%, and the resistance change due to the thermal cycle did not change within the control error.
In addition, the thermometer produced in Example 3 was also subjected to a cycle between 4K and 300K twice for the case where only the substrate was changed to fused silica (SiO 2 ), and the change in electric resistance was examined. As a result, as shown in FIG. 8, it was found that the thermal cycle stability was lower than that using Si as the substrate.
（実施例５）
　実施例３で作製した温度計を用い、４Ｋ及び２Ｋで、９Ｔまで磁場を変化させたときの温度誤差の変化を調べ、図９に示した。その結果、いずれの温度においても、温度誤差の変化は６ｍＫ以下であった。尚、測定は、Quantum-Design社のPPMS（Physical Properties Measurement System）で測定したが、温度制御精度が８ｍＫであり、磁場により測温誤差と同程度であった。
　以上より、本発明における窒化クロムは磁気抵抗効果が非常に小さく、磁気抵抗効果による測温誤差の温度依存性も極めて小さいことが分かった。 (Example 5)
Using the thermometer produced in Example 3, the change in temperature error when the magnetic field was changed up to 9T at 4K and 2K was shown in FIG. As a result, the change in temperature error was 6 mK or less at any temperature. The measurement was performed with PPMS (Physical Properties Measurement System) manufactured by Quantum-Design, but the temperature control accuracy was 8 mK, which was comparable to the temperature measurement error due to the magnetic field.
From the above, it was found that the chromium nitride in the present invention has a very small magnetoresistance effect, and the temperature dependence of the temperature measurement error due to the magnetoresistance effect is extremely small.
　本実施例の温度計は、磁場に感応し難く、０．３～４００Ｋの幅広い温度領域を測定できることが分かった。 It was found that the thermometer of this example is not sensitive to a magnetic field and can measure a wide temperature range of 0.3 to 400K.
（実施例６）
　反応性ＲＦマグネトロンスパッタリング法と、反応性ＤＣマグネトロンスパッタリング法とのそれぞれにより、製膜電力２００Ｗ、基板温度２００℃で、窒素分圧を変えながら、窒化クロム薄膜を形成した場合の薄膜の電気抵抗値変化を調べ、その結果を図１０、１１に示した。
　反応性ＲＦマグネトロンスパッタリング法、反応性ＤＣマグネトロンスパッタリング法のいずれの場合も、窒化クロム薄膜の電気抵抗値は、窒素分圧を高くするとともに一旦上昇し、その後、緩やかに低下した。しかし、反応性ＲＦマグネトロンスパッタリング法による場合は、電気抵抗値がピークに達したときの窒素分圧が約７％（５％と１０％との間）であったのに対し、反応性ＤＣマグネトロンスパッタリング法による場合は、約４０％であり、大きく異なっていた。この結果から、反応性ＲＦマグネトロンスパッタリング法の方がより窒化しやすく、好ましいことが分かった。 (Example 6)
The electric resistance of the thin film when a chromium nitride thin film is formed while changing the nitrogen partial pressure at a film forming power of 200 W and a substrate temperature of 200 ° C. by the reactive RF magnetron sputtering method and the reactive DC magnetron sputtering method, respectively. Changes were examined and the results are shown in FIGS.
In both the reactive RF magnetron sputtering method and the reactive DC magnetron sputtering method, the electric resistance value of the chromium nitride thin film once increased with increasing nitrogen partial pressure, and then gradually decreased. However, in the case of the reactive RF magnetron sputtering method, the nitrogen partial pressure when the electric resistance reached the peak was about 7% (between 5% and 10%), whereas the reactive DC magnetron. In the case of the sputtering method, it was about 40%, which was greatly different. From this result, it was found that the reactive RF magnetron sputtering method is more easily nitrided and preferable.
　また、反応性ＲＦマグネトロンスパッタリング法により作製した窒化クロム薄膜における電気抵抗値の温度依存性について調べた。その結果、図１２に示すように、窒素分圧を高くすると、窒化クロム薄膜の電気抵抗値の温度依存性が低下することが分かった。すなわち、窒化クロム薄膜を作製する場合のスパッタリング法における窒素分圧は高い方が好ましく、８０％以上がより好ましく、１００％がさらに好ましいことが分かった。 Also, the temperature dependence of the electrical resistance value in a chromium nitride thin film produced by a reactive RF magnetron sputtering method was examined. As a result, as shown in FIG. 12, when the nitrogen partial pressure was increased, it was found that the temperature dependence of the electrical resistance value of the chromium nitride thin film was lowered. That is, it was found that the nitrogen partial pressure in the sputtering method when producing a chromium nitride thin film is preferably high, more preferably 80% or more, and even more preferably 100%.
（実施例７）
　反応性ＲＦマグネトロンスパッタリング法により、窒素分圧１００％で、製膜電力を２００Ｗ（２．５Ｗ／ｃｍ２）と６００Ｗ（７．６Ｗ／ｃｍ２）とのそれぞれで窒化クロム薄膜を形成した場合の薄膜の電気抵抗値の温度依存性を調べた。その結果、図１３に示すように、製膜電圧が６００Ｗの場合では、２Ｋまで温度計として使用できるのに対し、２００Ｗの場合では、形成された薄膜の電気抵抗値は７Ｋで１ＭΩを超えており、製膜電圧は高い方がより低温域まで測定できる窒化クロム薄膜を作製できることが分かった。このため、２Ｋまで使用できる温度計に適用できる窒化クロム薄膜を作製するには、反応性ＲＦマグネトロンスパッタリング法における製膜電圧は、５００Ｗ（６．４Ｗ／ｃｍ２）以上が好ましく、６００Ｗ（７．６Ｗ／ｃｍ２）以上がより好ましい。 (Example 7)
In the case of forming a chromium nitride thin film by reactive RF magnetron sputtering with a nitrogen partial pressure of 100% and a film forming power of 200 W (2.5 W / cm 2 ) and 600 W (7.6 W / cm 2 ), respectively. The temperature dependence of the electrical resistance of the thin film was investigated. As a result, as shown in FIG. 13, when the film forming voltage is 600 W, it can be used as a thermometer up to 2K, whereas in the case of 200 W, the electric resistance value of the formed thin film exceeds 7 MΩ at 7K. Thus, it was found that a chromium nitride thin film that can be measured up to a lower temperature region can be produced with a higher film forming voltage. For this reason, in order to produce a chromium nitride thin film applicable to a thermometer that can be used up to 2K, the film forming voltage in the reactive RF magnetron sputtering method is preferably 500 W (6.4 W / cm 2 ) or more, and 600 W (7. 6 W / cm 2 ) or more is more preferable.
１　　基板
２　　膜
１０　温度計 1 Substrate 2 Film 10 Thermometer

Claims (10)

  1. 　少なくとも１００Ｋ以下で反強磁性となる窒化クロムを材料とする測温抵抗体。 Resistance thermometer made of chromium nitride that becomes antiferromagnetic at least 100K or less.
  2. 　少なくとも１００Ｋ以下で反強磁性となる窒化クロムの膜を、基板の上に設けてある温度計。 A thermometer in which a chromium nitride film that becomes antiferromagnetic at least 100K or less is provided on a substrate.
  3. 　前記窒化クロムの膜は、前記窒化クロムの結晶成長が抑制された薄膜で構成され、結晶粒径が１５ｎｍ以下である請求項２に記載の温度計。 3. The thermometer according to claim 2, wherein the chromium nitride film is formed of a thin film in which crystal growth of the chromium nitride is suppressed, and a crystal grain size is 15 nm or less.
  4. 　前記基板は、熱膨張係数が１×１０－６～５×１０－６／Ｋの範囲にある請求項２または３に記載の温度計。 4. The thermometer according to claim 2, wherein the substrate has a thermal expansion coefficient in a range of 1 × 10 −6 to 5 × 10 −6 / K.
  5. 　前記基板は、シリコン基板である請求項２～４のいずれか一項に記載の温度計。 The thermometer according to any one of claims 2 to 4, wherein the substrate is a silicon substrate.
  6. 　前記シリコン基板は、電気抵抗率が７０００Ωｃｍ以上である請求項５に記載の温度計。 The thermometer according to claim 5, wherein the silicon substrate has an electrical resistivity of 7000 Ωcm or more.
  7. 　前記窒化クロムの膜の上に、一対の電極を所定の電極間距離で配置し、特定の温度域における測定感度を高めた請求項２～６のいずれか一項に記載の温度計。 The thermometer according to any one of claims 2 to 6, wherein a pair of electrodes are disposed on the chromium nitride film at a predetermined inter-electrode distance to increase measurement sensitivity in a specific temperature range.
  8. 　基板の上に、少なくとも１００Ｋ以下で反強磁性となる窒化クロムの膜を設けた温度計において、前記窒化クロム膜の上に設ける一対の電極の電極間距離を変更することにより、測定感度の高い温度域を設定する温度計の設定方法。 In a thermometer in which a chromium nitride film that becomes antiferromagnetic at least 100K or less is provided on a substrate, the measurement sensitivity is high by changing the distance between the pair of electrodes provided on the chromium nitride film. Thermometer setting method to set the temperature range.
  9. 　製膜室内に、基板と金属クロムとを配置し、窒素の割合が８０％以上の雰囲気となるように窒素または窒素と希ガスとの混合ガスを導入し、金属クロムと窒素とを反応させて前記基板上に少なくとも１００Ｋ以下で反強磁性となる窒化クロムの膜を形成する温度計の製造方法。 A substrate and metallic chromium are placed in the film forming chamber, nitrogen or a mixed gas of nitrogen and rare gas is introduced so that the nitrogen ratio is 80% or more, and metallic chromium and nitrogen are reacted. A thermometer manufacturing method for forming a chromium nitride film which becomes antiferromagnetic at least 100K or less on the substrate.
  10. 　金属クロムと窒素とを反応させる際に、前記基板を１００℃以下に保つことにより、窒化クロムの結晶粒成長を抑制し、粒径を小さくする請求項９に記載の温度計の製造方法。 10. The method of manufacturing a thermometer according to claim 9, wherein when the metal chromium and nitrogen are reacted, the crystal growth of chromium nitride is suppressed and the particle size is reduced by keeping the substrate at 100 ° C. or lower.
PCT/JP2012/057016 2011-04-28 2012-03-19 Thermometry resistor and thermometer WO2012147432A1 (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014175004A1 (en) * 2013-04-26 2014-10-30 国立大学法人九州工業大学 Electrically conductive material and resistance thermometer using same
JP2017075854A (en) * 2015-10-15 2017-04-20 ニッタ株式会社 Temperature sensitive element
US10718680B2 (en) 2014-12-18 2020-07-21 Nitta Corporation Sensor sheet

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JP2001110606A (en) * 1999-10-12 2001-04-20 Osaka Prefecture Resistance bulb for thermometer unaffected by magnetic field under very low temperature
JP2008041888A (en) * 2006-08-04 2008-02-21 Hitachi Metals Ltd Thermistor material
JP2008224496A (en) * 2007-03-14 2008-09-25 Osaka Univ Thermophysical property measuring device, and thermophysical property measuring method

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001110606A (en) * 1999-10-12 2001-04-20 Osaka Prefecture Resistance bulb for thermometer unaffected by magnetic field under very low temperature
JP2008041888A (en) * 2006-08-04 2008-02-21 Hitachi Metals Ltd Thermistor material
JP2008224496A (en) * 2007-03-14 2008-09-25 Osaka Univ Thermophysical property measuring device, and thermophysical property measuring method

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014175004A1 (en) * 2013-04-26 2014-10-30 国立大学法人九州工業大学 Electrically conductive material and resistance thermometer using same
US10718680B2 (en) 2014-12-18 2020-07-21 Nitta Corporation Sensor sheet
JP2017075854A (en) * 2015-10-15 2017-04-20 ニッタ株式会社 Temperature sensitive element

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