JP2018036245A - Temperature sensor and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a temperature sensor provided with a protective film having high heat resistance as well as high adhesion to a thin film thermistor portion of a metal nitride material, and a manufacturing method thereof.
SOLUTION: An insulating base material 2, a thin film thermistor portion 3 formed of a metal nitride material for thermistor on the insulating base material, and pattern formation on at least one of the lower side and the upper side of the thin film thermistor portion facing each other. A pair of patterned electrodes 4 and an insulating nitride protective film 5 formed on the thin film thermistor portion are provided.
[Selection] Figure 1

Description

  The present invention relates to a temperature sensor suitable for a film type thermistor temperature sensor and the like, and a manufacturing method thereof.

A thermistor material used for a temperature sensor or the like is required to have a high B constant for high accuracy and high sensitivity. As such a thermistor material, transition metal oxides such as Mn, Co, and Fe were generally used. However, in recent years, development of a film type thermistor sensor in which a thermistor material is formed on a resin film has been studied. A metal nitride material for a thermistor that can be formed on a resin film has been developed (see, for example, Patent Document 1).
In addition, it can be formed without firing, and is at least one nitride material of Ti, V, Cr, Mn, Fe, Co, Ni, Si, Cu, and Al, and has the above crystal structure. Thus, materials capable of obtaining a high B constant have been developed (Patent Documents 2 to 7).

  The conventional thermistor temperature sensor using the metal nitride material for thermistor includes, for example, an insulating substrate such as a resin film, and a thin film thermistor portion formed of the metal nitride material for thermistor on the insulating substrate. A pair of pattern electrodes are formed on the thin film thermistor portion so as to face each other, and a polyimide resin covering the thin film thermistor portion together with the pattern electrodes.

JP 2013-205319 A JP 2014-123646 A JP 2014-236204 A JP2015-65408A JP2015-65417 A JP-A-2015-73077 JP-A-2015-73075

The following problems remain in the conventional technology.
In the above conventional technique, a polyimide resin is formed or bonded as an insulating protective film on the thin film thermistor portion of the metal nitride material, but the adhesion between the thin film thermistor portion of the metal nitride material and the polyimide resin is weak, There has been a demand for improved adhesion. In addition, an organic resin material such as a polyimide resin material is vulnerable to heat, and an inorganic protective film material having sufficient heat resistance has been desired. In particular, since the thermistor portion is often made of a ceramic material, there has been a demand for a heat-resistant ceramic protective film that also has insulating properties.

  The present invention has been made in view of the above-described problems, and provides a temperature sensor including a protective film having high heat resistance and high adhesion to a thin film thermistor portion of a metal nitride material, and a method for manufacturing the same. For the purpose.

  The present invention employs the following configuration in order to solve the above problems. That is, the temperature sensor according to the first invention includes an insulating substrate, a thin film thermistor portion formed of the metal nitride material for the thermistor on the insulating substrate, and a lower surface of the thin film thermistor portion facing each other. Or a pair of pattern electrodes patterned on at least one of the upper sides and an insulating nitride protective film formed on the thin film thermistor portion.

  That is, in this temperature sensor, since the insulating nitride protective film formed on the thin film thermistor portion formed of the metal nitride material for the thermistor is provided, the thin film thermistor portion and the insulating nitride which are nitrides with each other are provided. High adhesion to the protective film can be obtained, and the nitride protective film can provide higher heat resistance than the polyimide resin.

A temperature sensor according to a second invention is characterized in that, in the first invention, the crystal structures of the thin film thermistor portion and the insulating nitride protective film are the same hexagonal wurtzite type single phase. And
That is, in this temperature sensor, since the crystal structure of the thin film thermistor portion and the insulating nitride protective film is the same hexagonal wurtzite type single phase, the degree of lattice matching is high and higher adhesion is achieved. Can be secured.

A temperature sensor according to a third aspect of the present invention is the temperature sensor according to the second aspect, wherein the thin film thermistor portion has a thermistor characteristic M-A-N (where M is Ti, V, Cr, Mn, Fe, Co, Ni and It represents at least one of Cu and A represents Al or (Al and Si).), And the insulating nitride protective film is crystalline Al-N.
That is, in this temperature sensor, the thin film thermistor portion has a hexagonal wurtzite type thermistor characteristic M-A-N (where M is Ti, V, Cr, Mn, Fe, Co, Ni and Cu). And at least one of them, A represents Al or (Al and Si).) And the insulating nitride protective film is hexagonal wurtzite Al-N, so that the same crystal structure Al-N and M-A-N nitride are laminated and have a high degree of lattice matching with each other. Therefore, at the Al-N / M-A-N interface, the insulating nitride protective film of Al-N The effect of the crystal lattice on the M-A-N crystal lattice of the thin film thermistor is small, and as a result, the change in the electronic structure is extremely small. Change can be suppressed.

A temperature sensor according to a fourth aspect of the present invention is the temperature sensor according to the second aspect, wherein the thin film thermistor portion has a thermistor characteristic M-A-N (where M is Ti, V, Cr, Mn, Fe, Co, Ni and And at least one of Cu and A is Al or (Al and Si)), and the insulating nitride protective film is an insulating crystalline M′-Al—N (where M ′ Represents at least one of Ti, V, Cr, Mn, Fe, Co, Ni, and Cu.
That is, in this temperature sensor, the thin film thermistor portion is MAN having a hexagonal wurtzite type thermistor characteristic, and the insulating nitride protective film is a hexagonal wurtzite type crystal structure. Since it is an insulating crystalline M-Al-N having the same structure, it is a laminate of M-A-N and M'-Al-N having the same crystal structure, and has a high degree of lattice matching with each other. The influence of the M'-Al-N crystal lattice of the insulating nitride protective film on the M-A-N crystal lattice of the thin film thermistor part is very small at the interface between the protective film and the thin film thermistor part. As a result, the change in the electronic structure becomes extremely small, so that it is possible to further suppress the thermistor characteristic change in the thin film thermistor portion of MAN due to the formation of the protective film.
Note that when M = M ′, that is, when the M element and the M ′ element are the same, the degree of lattice matching between them is particularly high.

  A temperature sensor according to a fifth aspect of the present invention is characterized in that in any one of the third and fourth aspects, the M element is Ti.

A temperature sensor according to a sixth aspect of the present invention is the temperature sensor according to any one of the first to fifth aspects, wherein the insulating base is an insulating film.
That is, in this temperature sensor, since the insulating base material is an insulating film, the insulating base material of the flexible insulating film, the flexible thin film thermistor portion of MAN, and the crystalline Al-N Alternatively, a thin and film-like flexible temperature sensor is formed by the insulating crystalline M′-Al—N insulating nitride protective film. Therefore, the flexibility enables installation on a curved surface or the like, and the degree of installation freedom can be greatly improved.

A temperature sensor manufacturing method according to a seventh invention is a method for manufacturing the temperature sensor according to any one of the first to sixth inventions, wherein a thin film thermistor portion is formed on an insulating substrate by sputtering. A thin film thermistor portion forming step, a pattern electrode forming step of patterning a pair of pattern electrodes under or above the thin film thermistor portion, and an insulating nitride protective film formed on the thin film thermistor portion by sputtering A protective film forming step, wherein the protective film forming step performs reverse sputtering before the sputtering.
That is, in this temperature sensor manufacturing method, since the protective film forming step performs reverse sputtering before sputtering, the natural oxide film on the surface of the thin film thermistor part after sputtering is removed, and there is no influence of oxidation and is high A high-quality insulating nitride protective film having adhesiveness can be formed.

The present invention has the following effects.
That is, according to the temperature sensor and the manufacturing method thereof according to the present invention, since the insulating nitride protective film formed on the thin film thermistor portion formed of the metal nitride material for the thermistor is provided, the thin films that are nitrided with each other High adhesion between the thermistor portion and the insulating nitride protective film can be obtained, and higher heat resistance than that of the polyimide resin can be obtained by the nitride protective film. Therefore, dislocations at the interface between the thin film thermistor portion and the insulating nitride protective film are also reduced and are not easily peeled off, and can be used in a high-temperature environment and high reliability can be obtained.

In 1st Embodiment of the temperature sensor which concerns on this invention, and its manufacturing method, they are the top view and AA sectional view taken on the line which show a temperature sensor. In 1st Embodiment, it is sectional drawing which shows the manufacturing method of a temperature sensor in order of a process. In 2nd Embodiment of the temperature sensor which concerns on this invention, and its manufacturing method, they are the top view and BB sectional drawing which show a temperature sensor. In 2nd Embodiment, it is sectional drawing which shows the manufacturing method of a temperature sensor in order of a process. It is a cross-sectional TEM image which shows the comparative example 1 of the temperature sensor which concerns on this invention, and its manufacturing method. It is a cross-sectional TEM image which shows Example 1 of the temperature sensor which concerns on this invention, and its manufacturing method. It is a cross-sectional TEM image which shows Example 2 of the temperature sensor which concerns on this invention, and its manufacturing method. It is an electron beam diffraction image of the Ti-Al-N film section in comparative example 1 concerning the present invention. It is an electron beam diffraction image of the Ti-Al-N film cross section in Example 2 which concerns on this invention. In the Example which concerns on this invention, it is a graph which shows the result of the visual oblique incidence X-ray diffraction (XRD) when the incident angle of the Ti-Al-N film | membrane used as a thin film thermistor part is 1 degree. In the Example which concerns on this invention, it is a graph which shows the result of an oblique angle incident X-ray diffraction (XRD) when the incident angle of the Ti-Al-N film | membrane used as an insulating nitride protective film is 1 degree. In the examples according to the present invention, the results of oblique oblique incidence X-ray diffraction (XRD) when the incident angle of the thin film thermistor portion and the Ti—Al—N laminated film serving as the insulating nitride protective film is set to 1 degree. It is a graph to show. In the Example which concerns on this invention, it is a graph which shows the result of X-ray diffraction (XRD) at the time of setting the incident angle of the Ti-Al-N film | membrane used as a thin film thermistor part to 0 degree. In the Example which concerns on this invention, it is a graph which shows the result of X-ray diffraction (XRD) when the incident angle of the Ti-Al-N film | membrane used as an insulating nitride protective film is 0 degree. In the Example which concerns on this invention, it is a graph which shows the result of a X-ray diffraction (XRD) when the incident angle is set to 0 degree | times of the Ti-Al-N laminated film used as a thin film thermistor part and an insulating nitride protective film. It is a cross-sectional SEM photograph of the Ti-Al-N single layer film of FIG. It is a cross-sectional SEM photograph of the Ti-Al-N single layer film of FIG. It is a cross-sectional SEM photograph of the Ti-Al-N laminated film of FIG. In the Example which concerns on this invention, it is a graph which shows the lattice constant (a-axis length) of the Ti-Al-N film | membrane with respect to composition ratio Al / (Al + Ti). In the Example which concerns on this invention, it is a graph which shows the lattice constant (c-axis length) of the Ti-Al-N film | membrane with respect to composition ratio Al / (Al + Ti).

  Hereinafter, a first embodiment of a temperature sensor and a method for manufacturing the same according to the present invention will be described with reference to FIGS. 1 and 2. Note that in some of the drawings used for the following description, the scale is appropriately changed as necessary to make each part recognizable or easily recognizable.

  The temperature sensor 1 of this embodiment is a film type thermistor sensor, and as shown in FIG. 1, an insulating base material 2 and a thin film thermistor formed of a metal nitride material for the thermistor on the insulating base material 2. A portion 3, a pair of pattern electrodes 4 formed under the thin film thermistor portion 3 so as to face each other, and an insulating nitride protective film 5 formed on the thin film thermistor portion 3 are provided.

The crystal structure of the thin film thermistor portion 3 and the insulating nitride protective film 5 is the same hexagonal wurtzite type single phase, and the thin film thermistor portion 3 has a thermistor characteristic M-A-N (however, , M represents at least one of Ti, V, Cr, Mn, Fe, Co, Ni, and Cu, and A represents Al or (Al and Si).), And the insulating nitride protective film 5 Is crystalline Al—N or insulating crystalline M′—Al—N (where M ′ represents at least one of Ti, V, Cr, Mn, Fe, Co, Ni and Cu). . A is Al or (Al and Si), that is, Al, Al and Si, and includes at least Al.
In particular, in the present embodiment, Ti—Al—N having thermistor characteristics is employed as the thin film thermistor portion 3, and crystalline Al—N or insulating crystalline Ti—Al— is employed as the insulating nitride protective film 5. N is adopted. Note that insulating crystalline Ti—Al—N achieves a very high insulating property by sufficiently increasing the composition ratio Al / (Al + Ti) as compared to Ti—Al—N having thermistor characteristics.

  The insulating nitride protective film 5 has an insulating crystalline M′-Al—N (where M ′ represents at least one of Ti, V, Cr, Mn, Fe, Co, Ni, and Cu). ) M-A-N having the thermistor characteristics of the thin film thermistor section 3 (where M represents at least one of Ti, V, Cr, Mn, Fe, Co, Ni and Cu, and A represents Al or (Indicating Al and Si) The resistance value is preferably 1000 times or more. Note that the composition ratio Al / (Al + M ′) of the insulating crystalline M′-Al—N is sufficiently larger than the composition ratio A / (A + M) of M−A−N having thermistor characteristics. Extremely high insulation is achieved. Thus, if the resistance value of the insulating nitride protective film 5 is 1000 times or more that of the thin film thermistor part 3, the insulating nitride protective film 5 functions as a protective film having sufficiently high insulation with respect to the thin film thermistor part 3. The thermistor characteristics of the thermistor section 3 are not affected.

In the present embodiment, the thin film thermistor portion 3 has the general _formula: in _{Ti x Al y N z (0.70} ≦ y / (x + y) ≦ 0.95,0.4 ≦ z ≦ 0.5, x + y + z = 1) It consists of the metal nitride shown, and its crystal structure is a single phase of hexagonal wurtzite type.
The thin film thermistor portion 3 is a columnar crystal formed in a film shape and extending in a direction perpendicular to the surface of the film. Further, it is preferable that the c-axis is oriented more strongly than the a-axis in the direction perpendicular to the film surface. Since the c-axis orientation degree of the thin film thermistor portion 3 is high, crystalline Al—N or insulating crystalline M′—Al—N (where M ′ is Ti, V, Cr, Mn, Fe, Co, Ni, and Cu are also shown.) The c-axis orientation degree is improved and the lattice matching degree is increased, so that insulating nitride protection with higher adhesion can be achieved. A film 5 is formed.

The said insulating base material 2 is an insulating film, for example, is formed with the polyimide resin sheet. The insulating film may be PET: polyethylene terephthalate, PEN: polyethylene naphthalate, LCP (Liquid Crystal Polymer liquid crystal polymer), or the like.
The pair of pattern electrodes 4 has a plurality of comb portions 4a extending in the opposing direction.
The pattern electrode 4 is formed on the Cr bonding layer formed on the insulating base material 2 and on the exposed Cr bonding layer outside the thin film thermistor portion 3 and the insulating nitride protective film 5. And a noble metal electrode layer such as Au. That is, in this embodiment, the Cr bonding layer of the pattern electrode 4 is formed under the thin film thermistor portion 3.

A manufacturing method of the temperature sensor 1 will be described below with reference to FIG.
The manufacturing method of the temperature sensor 1 according to the present embodiment includes a pattern electrode forming step of patterning a pair of pattern electrodes 4 on the insulating base material 2 (under the thin film thermistor portion 3) facing each other, and an insulating group A thin film thermistor portion forming step for forming the thin film thermistor portion 3 on the material 2 and the pattern electrode 4 by sputtering, and a protective film forming step for forming the insulating nitride protective film 5 on the thin film thermistor portion 3 by sputtering. doing.
In the protective film forming step, reverse sputtering is performed before the insulating nitride protective film 5 is sputtered.

As a more specific example of the manufacturing method, the Cr bonding layer of the pattern electrode 4 is formed to a thickness of 20 nm on the insulating substrate 2 of the polyimide film having a thickness of 50 μm shown in FIG. An Au electrode layer is formed thereon with a thickness of 20 nm. These sputtering conditions are: ultimate vacuum 4.0 × 10 ⁻⁵ Pa, sputtering gas pressure 0.1 Pa, target input power (output) is 300 W for Cr bonding layer, 100 W for Au electrode layer, Ar gas atmosphere Went below.

  Next, after applying a resist solution on the deposited Au electrode layer with a spin coater, pre-baking was performed at 110 ° C. for 1 minute 30 seconds, and after exposure with an exposure apparatus, unnecessary portions were removed with a developer, and 150 ° C. Patterning is performed by post-baking for 5 minutes. Thereafter, unnecessary electrode portions are wet-etched in the order of commercially available Au etchant and Cr etchant, and a desired pattern electrode 4 is formed by resist stripping.

Next, a Ti—Al—N (Al / (Al + Ti) film is formed on the Cr bonding layer of the pattern electrode 4 and the insulating substrate 2 by a reactive sputtering method in a nitrogen-containing atmosphere using a Ti—Al alloy sputtering target. ) Ratio = 0.85) of the thin film thermistor portion 3 is formed with a film thickness of 200 nm. The sputtering conditions at that time were an ultimate vacuum of 4 × 10 ⁻⁵ Pa, a sputtering gas pressure of 0.2 Pa, a target input power (output) of 200 W, and a nitrogen gas fraction of 30 in a mixed gas atmosphere of Ar gas + nitrogen gas. %.
Thus, M-A-N (wherein M represents at least one of Ti, V, Cr, Mn, Fe, Co, Ni and Cu, and A represents Al or (Al and Si).) The thin film thermistor portion 3 is formed by reactive sputtering using a MA alloy sputtering target in a nitrogen-containing atmosphere.

  Next, after a resist solution is applied on the thin film thermistor portion 3 formed with a spin coater, pre-baking is performed at 110 ° C. for 1 minute 30 seconds, and after exposure with an exposure apparatus, unnecessary portions are removed with a developer. Patterning is performed by post-baking at 5 ° C. for 5 minutes. Thereafter, the unnecessary thin film thermistor portion 3 is wet-etched with a commercially available etchant to form a desired thin film thermistor portion 3 by resist stripping as shown in FIG.

Next, the natural oxide film on the surface of the thin film thermistor portion 3 is removed. It is preferable to perform plasma surface treatment by reverse sputtering as the oxide film removal step. Specifically, a surface oxide film (contaminated film such as a natural oxide film) formed on the surface of the thin film thermistor portion 3 by applying electric power to the substrate side before sputtering in the insulating nitride film forming step. Are removed by reverse sputtering.
The reverse sputtering conditions at this time are, for example, ultimate vacuum: 4 × 10 ⁻⁵ Pa, target applied power: 50 W, and 30 minutes in an Ar gas atmosphere. Note that the gas species used during reverse sputtering may be nitrogen gas or a mixed gas of Ar gas and nitrogen gas.

After the reverse sputtering oxide film removing step, an insulating nitride protective film 5 of Al—N or insulating Ti—Al—N is further formed on the thin film thermistor portion 3 by sputtering.
In the case of crystalline Al—N, an insulating nitride protective film 5 of crystalline Al—N is formed to a thickness of 500 nm by reactive sputtering in a nitrogen-containing atmosphere using an Al sputtering target. The sputtering conditions at that time were an ultimate vacuum of 4 × 10 ⁻⁵ Pa, a sputtering gas pressure of 0.2 Pa, a target input power (output) of 200 W, and a nitrogen gas fraction of 35 in a mixed gas atmosphere of Ar gas + nitrogen gas. %.
In the case of insulating crystalline Ti—Al—N, the composition ratio Al / (Al + Ti) is preferably sufficiently larger than crystalline Ti—Al—N having thermistor characteristics. Specifically, an insulating nitride protective film of Ti—Al—N (Al / (Al + Ti) ratio = 0.97) is formed by reactive sputtering in a nitrogen-containing atmosphere using a Ti—Al alloy sputtering target. 5 is formed with a film thickness of 200 nm. The sputtering conditions at that time were an ultimate vacuum of 4 × 10 ⁻⁵ Pa, a sputtering gas pressure of 0.25 Pa, a target input power (output) of 200 W, and a nitrogen gas fraction of 30 in a mixed gas atmosphere of Ar gas + nitrogen gas. %.
Thus, insulating nitride protection of insulating crystalline M′-Al—N (where M ′ represents at least one of Ti, V, Cr, Mn, Fe, Co, Ni and Cu). The film 5 is formed by reactive sputtering using a M′-Al alloy sputtering target in a nitrogen-containing atmosphere.

In the case where a plurality of temperature sensors 1 are manufactured at the same time, after forming the plurality of pattern electrodes 4, the thin film thermistor portion 3 and the insulating nitride protective film 5 on the large sheet of the insulating base material 2 as described above, The temperature sensor 1 is cut from the sheet.
In this way, for example, a temperature sensor 1 of a thin film type thermistor sensor having a size of 1.0 × 0.5 mm and a thickness of 0.1 mm is obtained.

  As described above, the temperature sensor 1 according to this embodiment includes the insulating nitride protective film 5 formed on the thin film thermistor portion 3 formed of the metal nitride material for the thermistor. High adhesion between the thermistor portion 3 and the insulating nitride protective film 5 can be obtained, and higher heat resistance than that of the polyimide resin can be obtained by the insulating nitride protective film 5 made of nitride.

Further, since the crystal structure of the thin film thermistor portion 3 and the insulating nitride protective film 5 is the same hexagonal wurtzite type single phase, the lattice matching degree is high with each other, and higher adhesion is ensured. Can do.
In particular, the thin film thermistor portion 3 is a hexagonal wurtzite type MAN (where M represents at least one of Ti, V, Cr, Mn, Fe, Co, Ni and Cu, and A Represents Al or (Al and Si)), and when the insulating nitride protective film 5 is a hexagonal wurtzite crystalline Al-N, the crystalline Al- N and M-A-N nitride are laminated and have a high degree of lattice matching with each other. Therefore, at the Al-N / M-A-N interface, the crystalline Al-N of the insulating nitride protective film 5 is formed. The influence of the crystal lattice on the M-A-N crystal lattice of the thin film thermistor section 3 is small, and as a result, the change in the electronic structure is extremely small. The thermistor characteristic change can be suppressed.

  Further, the thin film thermistor portion 3 has a hexagonal wurtzite type thermistor characteristic MAN (where M is at least one of Ti, V, Cr, Mn, Fe, Co, Ni and Cu). And A represents Al or (Al and Si).) And the insulating nitride protective film 5 has an insulating crystalline M′-Al— having a hexagonal wurtzite crystal structure. In the case of N (where M ′ represents at least one of Ti, V, Cr, Mn, Fe, Co, Ni, and Cu), M-A-N and M′-Al— having the same crystal structure are used. N is laminated and has a high degree of lattice matching with each other. Therefore, at the interface between the insulating nitride protective film 5 and the thin film thermistor portion 3, the crystalline M′-Al—N crystal of the insulating nitride protective film 5 The effect of the lattice on the M-A-N crystal lattice of the thin film thermistor section 3 is very small. Ku, as a result, the change in the electronic structure is extremely small, it is possible to further suppress the thermistor characteristic change of the thin film thermistor portion 3 of M-A-N by the protective film formation. Note that, when M = M ′, that is, when the M element and the M ′ element are the same (for example, M = M ′ = Ti), the degree of lattice matching is particularly high.

  Furthermore, since the insulating base material 2 is an insulating film, the insulating base material 2 of a flexible insulating film and the flexible thin film thermistor portion 3 of M-A-N and crystalline Al-N or insulating With the crystalline nitride M′-Al—N insulating nitride protective film 5, a thin and film-like flexible temperature sensor is formed. Therefore, the flexibility enables installation on a curved surface or the like, and the degree of installation freedom can be greatly improved.

  Moreover, in the manufacturing method of the temperature sensor 1 of this embodiment, since the protective film forming step performs reverse sputtering before sputtering, the natural oxide film or the like on the surface of the thin film thermistor portion 3 after sputtering is removed, and oxidation is performed. It is possible to form a high-quality insulating nitride protective film 5 having no influence and high adhesion.

  Next, a second embodiment of the temperature sensor and the manufacturing method thereof according to the present invention will be described below with reference to FIGS. Note that, in the following description of the embodiment, the same components described in the above embodiment are denoted by the same reference numerals, and the description thereof is omitted.

The difference between the second embodiment and the first embodiment is that, in the first embodiment, the pattern electrode 4 is formed on the insulating substrate 2, that is, below the thin film thermistor portion 3. The temperature sensor 21 of the second embodiment is that the pattern electrode 4 is formed on the thin film thermistor portion 3 as shown in FIGS. 3 and 4.
The second embodiment is also different from the first embodiment in that the insulating nitride protective film 5 is formed on the thin film thermistor portion 3 so as to cover the pattern electrode 4. However, there is no technical difference in that the insulating nitride protective film 5 is formed on the thin film thermistor portion 3 in the portion not covered with the pattern electrode 4.

  That is, in the manufacturing method of the temperature sensor 21 of the second embodiment, as shown in FIG. 4A, a thin film thermistor part forming step of forming the thin film thermistor part 3 on the insulating substrate 2 by sputtering, 4 (b), a pattern electrode forming step of patterning a pair of pattern electrodes 4 on the thin film thermistor portion 3 so as to face each other, and a pattern electrode 4 as shown in FIG. 4 (c). And a protective film forming step of forming an insulating nitride protective film 5 on the thin film thermistor portion 3 by sputtering.

In addition, the manufacturing method and manufacturing conditions of each film | membrane in each said process are the same as that of what was described in 1st Embodiment.
Therefore, the temperature sensor 21 of the second embodiment includes the insulating nitride protective film 5 formed on the thin film thermistor portion 3 formed of the thermistor metal nitride material, as in the first embodiment. Therefore, high adhesion between the thin film thermistor portion 3 and the insulating nitride protective film 5 which are nitrides can be obtained, and higher heat resistance than that of the polyimide resin can be obtained by the nitride protective film 5.

  The temperature sensor 21 of the second embodiment is manufactured by changing the film thickness of the crystalline Al—N insulating nitride protective film 5 and measuring the resistance values at 25 ° C. and 50 ° C. in a constant temperature bath. The B constant was calculated from the resistance values at 25 ° C. and 50 ° C. The results are shown in Table 1. It has been confirmed that the manufactured temperature sensor 21 is a thermistor having a negative temperature characteristic from resistance values of 25 ° C. and 50 ° C. In Table 1, the insulating nitride protective film 5 is described as an Al—N protective film.

In addition, the B constant calculation method in this invention is calculated | required by the following formula | equation from each resistance value of 25 degreeC and 50 degreeC as mentioned above.
B constant (K) = ln (R25 / R50) / (1 / T25-1 / T50)
R25 (Ω): resistance value at 25 ° C. R50 (Ω): resistance value at 50 ° C. T25 (K): 298.15K 25 ° C. is displayed as an absolute temperature T50 (K): 323.15K 50 ° C. is displayed as an absolute temperature

  From the above measurement results, even when an Al—N insulating nitride film (insulating nitride protective film 5) is formed on the Ti—Al—N film, the resistance value and the B constant hardly change. Recognize. Crystalline Al-N and Ti-Al-N both have a hexagonal wurtzite crystal structure and a high degree of lattice matching with each other, so that an insulating nitride is present at the Al-N / Ti-Al-N interface. The influence of the crystalline Al—N crystal lattice of the protective film 5 on the Ti—Al—N crystal lattice of the thin film thermistor portion 3 is small, and as a result, the change in the electronic structure becomes extremely small. -Thermistor characteristic change of the Al-N thin film thermistor part 3 can be suppressed.

  In the second embodiment, since the pattern electrode 4 is formed on the Ti—Al—N film, the resistance value can be adjusted by trimming. Even if the crystalline Al—N of the insulating nitride protective film 5 is formed, the change in the thermistor characteristic of the Ti—Al—N thin film is suppressed. -A thin film material suitable for forming an insulating protective film on an Al-N thin film thermistor element.

  Next, the results of evaluating the temperature sensor according to the present invention and the method for manufacturing the same according to the example manufactured based on the above embodiment will be specifically described with reference to FIGS.

<Production of film evaluation element>
As examples and comparative examples of the present invention, the temperature sensor shown in FIG. 1 was fabricated as a film evaluation element as follows.
First, a thermistor characteristic is formed on a substrate _{2 of} a Si substrate with a thermal oxide film (SiO ₂ ) by using a Ti—Al alloy target having a composition ratio of Al / (Ti + Al) = 0.85 by reactive sputtering. Example 1 in which a Ti—Al—N film (thin film thermistor portion 3) having a thickness of 100 nm was formed and a crystalline Al—N film (insulating nitride protective film 5) was formed thereon to a thickness of 500 nm was produced. did.
Further, a Ti—Al—N film (thin film thermistor portion 3) having thermistor characteristics is formed on the base material 2 of the polyimide substrate, and the composition ratio Al / (Ti + Al) = 0.97 is formed thereon. Example 2 in which an insulating crystalline Ti—Al—N film (insulating nitride protective film 5) was formed to a thickness of 200 nm was produced using the Ti—Al alloy target described above.
A crystalline Al—N film (insulating nitride protective film 5) and a crystalline Ti—Al—N film having a composition ratio of Al / (Ti + Al) = 0.97 (insulating nitride protective film 5) Has confirmed that it has a specific resistance of 1000 times or more than that of a Ti-Al-N film (thin film thermistor part 3) having thermistor characteristics with a composition ratio of Al / (Ti + Al) = 0.85. It has been confirmed that it functions as a protective film having sufficiently high insulation with respect to the portion 3 and does not affect the thermistor characteristics of the thin film thermistor portion 3.

In Example 1, the surface treatment was performed by Ar reverse sputtering after the thin film thermistor portion 3 was formed, and then the insulating nitride protective film 5 of a crystalline Al—N film was continuously formed.
In the continuous film formation, in order to prevent surface oxidation of the thin film thermistor portion 3 after the surface treatment, the insulating nitride protective film 5 is immediately formed in the same film formation apparatus after the surface treatment without opening to the atmosphere. It means to film.

In Example 2, after the thin film thermistor portion 3 is formed and opened to the atmosphere, surface treatment is performed by Ar reverse sputtering, and then an insulating nitride protective film of an insulating crystalline Ti—Al—N film is formed. 5 was deposited.
As Comparative Example 1, a Ti-Al alloy target having a composition ratio of Al / (Ti + Al) = 0.85 was used, and Ti having thermistor characteristics on the substrate 2 of the Si substrate with the thermal oxide film (SiO ₂ ) was used. An Al—N film (thin film thermistor portion 3) having a thickness of 100 nm was formed, and an insulating nitride protective film 5 was not formed.

<Evaluation of crystal orientation by electron diffraction>
The degree of crystal orientation in Comparative Example 1 and Examples 1 and 2 was analyzed using a TEM (transmission electron microscope). A cross-sectional TEM image of Comparative Example 1 is shown in FIG. 5, and cross-sectional TEM images of Examples 1 and 2 are shown in FIGS.
In addition, FIG. 8 shows an electron diffraction image of the cross section of the Ti—Al—N film in Comparative Example 1. Further, an electron diffraction image of the cross section of the insulating crystalline Ti—Al—N film, which is the insulating nitride protective film 5 in Example 2, is shown in FIG. 9A, and the thin film thermistor portion in Example 2 is used. 9 shows a wide range electron diffraction pattern including both the Ti—Al—N film having the thermistor characteristic 3 and the insulating crystalline Ti—Al—N film as the insulating nitride protective film 5. Shown in (b).
The vertical direction of these electron beam diffraction images coincides with the direction perpendicular to the substrate surface, that is, the growth direction of the columnar crystals of the Ti—Al—N film.

From the cross-sectional TEM images, it can be seen that in each of the comparative examples and examples, a dense columnar crystallized Ti—Al—N film is formed as the thin film thermistor portion 3 and has a high degree of crystal orientation. . In both Examples 1 and 2, it can be seen that a dense columnar crystallized film is formed as the insulating nitride protective film 5 and has a high degree of crystal orientation. In particular, in Example 2 formed on a polyimide substrate, a dense columnar crystallized film is formed in each of the Ti—Al—N film and the insulating Ti—Al—N film of the thin film thermistor portion 3. I understand.
Further, from the electron beam diffraction images, in the comparative example and the example, the diffraction points of 002 and 00-2 are detected in the direction perpendicular to the substrate (the vertical direction in the figure). It can be seen that a crystallized film having a high degree of c-axis orientation is formed in the vertical direction.
Particularly, in Example 2, the surface treatment by Ar reverse sputtering of the crystalline Ti—Al—N film of the thin film thermistor portion 3 is performed, and a very small surface on the crystalline Ti—Al—N film of the thin film thermistor portion 3 is obtained. The oxide film is also removed, and the Ti—Al—N film of the insulating nitride protective film 5 can further nitride the Ti—Al—N film crystal from the initial crystal growth, and the c-axis crystal It is possible to obtain an insulating Ti—Al—N film having excellent orientation and high crystallinity.

<Evaluation of crystal orientation by X-ray diffraction>
Next, the embodiment of the present invention is a single-phase film of a wurtzite type phase, and since the orientation is strong, the a-axis orientation in the crystal axis in the direction perpendicular to the thin film thermistor portion 3 (film thickness direction). The c-axis orientation was investigated using Grazing Incidence X-ray Diffraction. At this time, the peak intensity ratio of (100) (hkl index indicating a-axis orientation) and (002) (hkl index indicating c-axis orientation) was measured in order to investigate the orientation of crystal axes.

The oblique oblique incidence X-ray diffraction conditions were that the tube was Cu and the incident angle was 1 degree. FIG. 10 is an XRD profile obtained by examining a Ti—Al—N single layer film (thin film thermistor portion) having an Al / (Al + Ti) ratio = 0.85 on a Si substrate with a thermal oxide film. It is the XRD profile which investigated about the Ti-Al-N single layer film (insulating nitride protective film) of Al / (Al + Ti) ratio = 0.97 on Si substrate with a thermal oxide film. FIG. 12 shows a Ti—Al—N film (thin film thermistor portion) having an Al / (Al + Ti) ratio = 0.85 and a crystalline Ti having an Al / (Al + Ti) ratio = 0.97 on a thermal oxide film Si substrate. It is the XRD profile which investigated the laminated film which laminated | stacked -Al-N film | membrane (insulating nitride protective film). (Note that the peak of (*) in FIGS. 10 to 12 is a peak derived from the Si substrate with the thermal oxide film, and is not a peak corresponding to the wurtzite type crystal phase.)
Further, with respect to each of the Ti—Al—N single layer film and the Ti—Al—N laminated film shown in FIGS. 10 to 12, the incident angle is set to 0 degree, and symmetrical measurement is performed in the range of 2θ = 20 to 100 degrees (general The results of (θ-2θ measurement) are shown in FIGS.

  As can be seen from these results, in any of the above Ti—Al—N films, no (100) peak was detected, indicating that the c-axis orientation is extremely strong. In particular, also in the laminated film of the crystalline Ti—Al—N film (thin film thermistor portion) having the thermistor characteristics and the insulating crystalline Ti—Al—N film (insulating nitride protective film) shown in FIG. It can be seen that the c-axis orientation is extremely strong. (The peak with a small half-value width detected in the vicinity of 33 degrees in FIGS. 13 and 15 is a peak derived from Si of the Si substrate with a thermal oxide film.)

<Evaluation of crystal form>
Next, cross-sectional SEM photographs of the Ti—Al—N single layer film and the Ti—Al—N laminated film of FIGS. 10 to 12 are shown in FIGS.
The samples of these examples are obtained by cleaving and cleaving a Si substrate with a thermal oxide film. Moreover, it is the photograph which observed the inclination at an angle of 45 degrees.

As can be seen from these photographs, both the Ti—Al—N single layer film and the Ti—Al—N multilayer film are formed of dense columnar crystals. That is, it has been observed that columnar crystals grow in a direction perpendicular to the substrate surface. The fracture of the columnar crystal occurred when the Si substrate with a thermal oxide film was cleaved.
When the aspect ratio of the columnar crystal is defined as (length) / (grain size), each of the Ti—Al—N single layer film and the Ti—Al—N laminated film has a large aspect ratio of 6 or more. The particle diameter of the columnar crystals is about 10 nm ± 5 nmφ, and the particle diameter is small and a dense film is obtained.

<Lattice constant>
Next, regarding the lattice constant of Ti—Al—N having a wurtzite crystal structure (hexagonal, space group P6 ₃ mc) when the composition ratio Al / (Al + Ti) is changed, the a-axis length and the c-axis length The examination results are shown in FIG. 19 and FIG. The lattice constant was calculated from the XRD result.
As can be seen from these results, the ionic radius of Ti is larger than that of Al (see Table 2), and the Ti element is partially substituted at the Al site and is dissolved (that is, the composition ratio Al / (Al + Ti) decreases. While the c-axis length (columnar crystal growth direction) does not change much, the a-axis length (direction perpendicular to the columnar crystal growth direction, ie, the direction perpendicular to the substrate) increases. The lattice mismatch with the crystalline Al—N film is large. However, in the composition range of the present invention, since crystalline Al—N is epitaxially grown on crystalline Ti—Al—N, other M elements (V, Cr, Mn, Fe, In the M-Al-N film substituted with Co, Ni and Cu), the a-axis length is smaller than that of the Ti-Al-N film, and the amount of lattice mismatch with the crystalline Al-N film is considered to be small. Therefore, in the M-Al-N film (V, Cr, Mn, Fe, Co, Ni and Cu), it is possible to epitaxially grow a crystalline Al-N film on the M-Al-N film similarly. is there.
Further, for the same reason as described above, an insulating crystalline M′-Al—N film (where M ′ is Ti, V, Cr, Mn, Fe, etc.) on the crystalline M—Al—N film having thermistor characteristics. It is possible to epitaxially grow at least one of Co, Ni and Cu.

  The technical scope of the present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention.

For example, in each of the above embodiments, Cr is used as a pattern electrode formed above or below the thin film thermistor portion, but a pattern electrode having a multilayer structure of Cr / Au / Cr may be employed.
Moreover, although crystalline Ti-Al-N is used as a thin film thermistor part in each said embodiment, it is described in patent documents 2-7, without being specifically limited to crystalline Ti-Al-N. A nitride thermistor thin film having the same hexagonal wurtzite crystal structure as crystalline Al—N, general formula: M _x A _y N _z (where M is Ti, V, Cr, Mn, Fe , Co, Ni and Cu, and A represents Al or (Al and Si) 0.70 ≦ y / (x + y) ≦ 0.98, 0.4 ≦ z ≦ 0.5, x + y + z = 1) is also applicable.
In each of the embodiments described above, crystalline M′-Al—N such as crystalline Al—N or insulating crystalline Ti—Al—N is used as the insulating nitride protective film. _If the resistance value of the _{xA y} N _z nitride thermistor thin film is at least 1000 times that of the material employed in the thin film thermistor part, the thin film thermistor part 3 has sufficiently high insulation. Since it functions as a film and does not affect the thermistor characteristics of the thin film thermistor section 3, it can be used as an insulating nitride protective film.
For example, even if the above-mentioned “y / (x + y)”, that is, A / (M ′ + A) is 0.98 or less, the insulating nitride has a resistance value 1000 times higher than that of the thin film thermistor portion. In the present invention, the protective film has a relatively sufficient insulating property with respect to the thin film thermistor portion. For example, when M = Ti, M ′ = Ti, and A = Al, a thin film thermistor portion with Al / (Ti + Al) of 0.85 has a resistivity of 2.47 × 10 ³ Ωcm, but Al / In the insulating nitride protective film having (Ti + Al) of 0.97, the resistivity at 25 ° C. is 2.41 × 10 ⁸ Ωcm. Therefore, the insulating nitride protective film with Al / (Ti + Al) of 0.97 has a resistance value about 100,000 times that of the thin film thermistor portion with Al / (Ti + Al) of 0.85. It functions as an insulating base.
An insulating nitride protective film with Al / (Ti + Al) of 0.91 has a resistivity of 1.38 × 10 ⁵ Ωcm at 25 ° C., but an insulating nitride with Al / (Ti + Al) of 0.97. In the protective film, the resistivity at 25 ° C. is 2.41 × 10 ⁸ Ωcm. Therefore, an insulating nitride protective film having an Al / (Ti + Al) of 0.97 has a resistance value 1000 times or more that of a thin film thermistor portion having an Al / (Ti + Al) of 0.91. It functions as a protective film having insulating properties. The resistance value of the insulating nitride protective film and the thin film thermistor portion is actually measured one formed in the thermal oxide film (SiO ₂₎ with the Si substrate.

As described above, the crystal structure of the wurtzite type is a hexagonal space group P6 ₃ mc (No. 186), and M and A belong to the same atomic site (M is Ti, V, Cr, Mn , Fe, Co, Ni and Cu, and A represents Al or (Al and Si).) In a so-called solid solution state. The wurtzite type has an apex-connected structure of (M, A) N ₄ tetrahedron, the closest site of (M, A) site is N (nitrogen), and (M, A) has nitrogen 4 coordination. Take.

In addition to Ti, V (vanadium), Cr (chromium), Mn (manganese), Fe (iron), Co (cobalt), Ni (nickel), and Cu (copper) are the same as Ti in the above crystal structure. It can exist at an atomic site and can be an element of M. The effective ionic radius is a physical property value often used for grasping the distance between atoms. When the literature value of Shannon's ionic radius, which is well known, is used, it is logically considered that W _x M of the wurtzite type. _y N _z (where, M is Ti, V, Cr, Mn, Fe, Co, along with indicating at least one of Ni and Cu, a represents Al or (Al and Si).) can be estimated that is obtained .
Table 2 below shows effective ionic radii of each ion species of Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Si (refer to RDShannon, Acta Crystallogr., Sect. A, 32, 751). (1976)).

The wurtzite type is tetracoordinate. When the effective ionic radius of tetracoordinate with respect to M is seen, Ni <Cu <Co <Fe <Mn in the case of divalent, and Al <Fe in the case of trivalent. In the case of tetravalent, Mn <Co <Cr <Ti, and in the case of pentavalent, Cr <V. From these results, it is considered that (Al, Cu, Co, Ni, Fe, Mn) <Cr <(V, Ti). (Ti and V or Cu, Co, Ni, Fe, Mn, and Al can not be distinguished in magnitude relation between ionic radii.) However, since the four-coordinate data have different valences, strict comparison Therefore, comparison was made using data of 6-coordinate (MN ₆ octahedron) when fixed to a trivalent ion for reference. In Table 2, HS indicates a high spin state, and LS indicates a low spin state. It can be seen that, in the low spin state (LS), the ionic radius is Al <Cu <Co <Fe <Mn <Ni <Cr <V <Ti. (In the high spin state, the ionic radius of Mn, Fe, Co, and Ni is larger than that of Al and smaller than that of Ti.)
By replacing the Al site of crystalline Al-N in the insulator with M such as Ti, thermistor characteristics can be obtained by conducting carrier doping and increasing electrical conduction. For example, the Al site is replaced with Ti. In this case, since Ti has a larger effective ionic radius than Al, as a result, the average ionic radius between Al and Ti increases. As a result, it can be estimated that the interatomic distance increases and the lattice constant increases.

Actually, in Patent Documents 2 to 7, a wurtzite type M _x A _y N _z (where M represents at least one of Ti, V, Cr, Mn, Fe, Co, Ni and Cu, and A Represents Al or (Al and Si)), and the thermistor characteristics are obtained. Further, it has been reported that an increase in lattice constant by replacing Al sites of AlN with Ti or the like has been confirmed from X-ray data. As for Si, the magnitude relationship between the ionic radii of Si and Al cannot be determined from Table 2. However, in Patent Document 5, the wurtzite type of M _x A _y N _z containing both Al and Si is used. It has been reported that it has a crystal structure and further has thermistor characteristics.

In order to epitaxially grow crystalline Al—N on the M _x A _y N _z film, an M element having an (Al, M) -N interatomic distance closer to the Al—N interatomic distance is selected. It is necessary to select an M element having an ionic radius closer to that of Al. In particular, the 3d transition metal elements (Ti, V, Cr, Mn, Fe, Co, Ni, Cu) shown in Table 2 are 4d transition metal elements (for example, Zr, Nb, Mo), 5d transition metal elements (for example, , Hf, Ta, W) Nitride thermistor epitaxial film having an ionic radius smaller than that of Al and closer to the ionic radius of Al, and thus having an Al—N interatomic distance closer to (Al, M) —N interatomic distance A crystalline Al—N film can be formed on the substrate.

  DESCRIPTION OF SYMBOLS 1,21 ... Temperature sensor, 2 ... Insulating base material, 3 ... Thin film thermistor part, 4 ... Pattern electrode, 5 ... Insulating nitride protective film

Claims (7)

An insulating substrate;
A thin film thermistor portion formed of a metal nitride material for thermistor on the insulating substrate;
A pair of pattern electrodes patterned on the thin film thermistor portion opposite to each other;
A temperature sensor comprising an insulating nitride protective film formed on the thin film thermistor portion. The temperature sensor according to claim 1,
The temperature sensor, wherein the thin film thermistor portion and the insulating nitride protective film have the same hexagonal wurtzite type single phase. The temperature sensor according to claim 2,
The thin-film thermistor portion has thermistor characteristics M-A-N (where M represents at least one of Ti, V, Cr, Mn, Fe, Co, Ni and Cu, and A represents Al or (Al and Si).)
The temperature sensor, wherein the insulating nitride protective film is crystalline Al-N. The temperature sensor according to claim 2,
The thin-film thermistor portion has thermistor characteristics M-A-N (where M represents at least one of Ti, V, Cr, Mn, Fe, Co, Ni and Cu, and A represents Al or (Al and Si).)
The insulating nitride protective film is an insulating crystalline M′-Al—N (where M ′ represents at least one of Ti, V, Cr, Mn, Fe, Co, Ni and Cu). A temperature sensor characterized by being. The temperature sensor according to claim 3 or 4,
The temperature sensor characterized in that the element of M is Ti. The temperature sensor according to any one of claims 3 to 5,
The temperature sensor, wherein the insulating substrate is an insulating film. A method for manufacturing the temperature sensor according to any one of claims 1 to 6,
A thin film thermistor part forming step of forming a thin film thermistor part on an insulating substrate by sputtering;
A pattern electrode forming step of patterning a pair of pattern electrodes on at least one of the thin film thermistor portions opposite to or above each other;
A protective film forming step of forming an insulating nitride protective film on the thin film thermistor portion by sputtering,
The method for manufacturing a temperature sensor, wherein the protective film forming step performs reverse sputtering before the sputtering.