阅读说明：本技术 热敏电阻及其制造方法和热敏电阻传感器 (Thermistor, method for manufacturing thermistor, and thermistor sensor ) 是由 藤田利晃 铃木峻平 佐古渚 千歳范寿 长友宪昭 于 2018-12-17 设计创作，主要内容包括：本发明提供一种耐热试验前后的电阻值变化比较小且可得到高B常数的热敏电阻及其制造方法和热敏电阻传感器。本发明所涉及的热敏电阻为形成于基材(2)上的热敏电阻(1),其具备：中间层叠部(7),形成于基材上；及主金属氮化膜层(4),由金属氮化物的热敏电阻材料形成于中间层叠部上,中间层叠部具备：基底热敏电阻层(3),由金属氮化物的热敏电阻材料形成；及中间氧氮化层(3a),形成于基底热敏电阻层上,主金属氮化膜层形成于中间氧氮化层上,中间氧氮化层是通过正下方的基底热敏电阻层的热敏电阻材料被氧化而形成的金属氧氮化层。(The invention provides a thermistor which has small resistance value change before and after a heat resistance test and can obtain a high B constant, a manufacturing method thereof and a thermistor sensor. The thermistor according to the present invention is a thermistor (1) formed on a substrate (2), and includes: an intermediate laminated part (7) formed on the base material; and a main metal nitride film layer (4) formed of a thermistor material of metal nitride on the intermediate laminated part, the intermediate laminated part including: a base thermistor layer (3) formed of a thermistor material of metal nitride; and an intermediate oxynitride layer (3a) formed on the base thermistor layer, the main metal nitride film layer being formed on the intermediate oxynitride layer, the intermediate oxynitride layer being a metal oxynitride layer formed by oxidizing the thermistor material of the base thermistor layer immediately below.)

1. A thermistor formed on a substrate, the thermistor comprising:

an intermediate laminated portion formed on the base material; and

a main metal nitride film layer formed of a thermistor material of metal nitride on the intermediate laminated portion,

the intermediate laminated part is formed by laminating two layers of a base thermistor layer and an intermediate oxynitride layer in one or more pairs, the base thermistor layer being formed of a thermistor material of metal nitride; the intermediate oxynitride layer is formed on the base thermistor layer,

the primary metal nitride film layer is formed on the intermediate oxynitride layer on the uppermost portion of the intermediate laminated part,

the intermediate oxynitride layer is a metal oxynitride layer formed by oxidizing a thermistor material of the underlying thermistor layer directly below.

2. A thermistor according to claim 1,

the composition of the substrate thermistor layer and the main metal nitride film layer is the same.

3. A thermistor according to claim 1,

the intermediate laminated part is formed by laminating two layers of the base thermistor layer and the intermediate oxynitride layer on the base material repeatedly in this order.

4. A thermistor according to claim 1,

the substrate thermistor layer and the main metal nitride film layer are M-A-N, M '-Al-N or G-A' -Al-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; m' represents at least one of Zr, Nb, Mo, Hf, Ta and W; g represents at least one of Ti, V, Cr, Mn, Fe and Co, and A' represents at least one of Sc, Zr, Mo, Nb and W.

The crystal structure of the main metal nitride film layer is a hexagonal wurtzite single phase.

5. A thermistor according to claim 4,

the substrate thermistor layer and the main metal nitride film layer are M-A-N, the M element in the M-A-N is Ti, and the A element is Al.

6. A thermistor according to claim 1,

the substrate is an insulating film.

7. A thermistor sensor is characterized by comprising:

a thermistor according to claim 1; and

and a pair of opposing electrodes formed on the main metal nitride film layer so as to face each other.

8. A method of manufacturing a thermistor according to claim 1, the method comprising:

an intermediate laminated part forming step of forming an intermediate laminated part on the base material; and

a main metal nitride film layer forming step of forming the main metal nitride film layer from a thermistor material of a metal nitride on the intermediate laminated portion,

the intermediate laminated part forming step is performed by repeating two steps of a base thermistor layer forming step of forming the base thermistor layer from a thermistor material of a metal nitride and an intermediate oxynitride layer forming step of forming an intermediate oxynitride layer on the base thermistor layer one or more times,

in the primary metal nitride film layer forming step, the primary metal nitride film layer is formed on the uppermost intermediate oxynitride layer of the intermediate laminated part,

in the intermediate oxynitride layer forming step, the intermediate oxynitride layer is formed by oxidizing the surface of the base thermistor layer.

9. A method of manufacturing a thermistor according to claim 8,

in the intermediate stacked portion forming step, the base thermistor layer forming step and the intermediate oxynitride layer forming step are sequentially repeated a plurality of times.

Technical Field

The present invention relates to a thermistor capable of obtaining a high B constant, a method for manufacturing the same, and a thermistor sensor.

Background

A thermistor material used in a temperature sensor or the like requires a high B constant to achieve high accuracy and high sensitivity. In recent years, as such a thermistor material, a metal nitride material which is not fired and does not require heat treatment and can obtain a high B constant has been developed.

For example, as a metal nitride material for a thermistor that is not fired and can be directly formed on an insulating substrate, the present inventors have developed a metal nitride material for a thermistor that is composed of a metal nitride represented by the general formula: ti_xAl_yN_zA metal nitride represented by (0.70. ltoreq. y/(x + y). ltoreq.0.95, 0.4. ltoreq. z.ltoreq.0.5, and x + y + z 1), and having a crystal structure of a hexagonal wurtzite-type single phase (patent document 1). Further, a material which can be formed by non-firing and is at least one of Ti, V, Cr, Mn, Fe, Co, Ni, Si, Cu, and Al, has been developedA nitride material having the above crystal structure and capable of obtaining a high B constant (patent documents 2 to 7).

Similarly, as a metal nitride material for a thermistor which is not fired and can be directly formed on an insulating base material, a material comprising a metal nitride represented by the general formula: m_xAl_yN_z(wherein M represents at least one of Zr, Nb, Mo, Hf, Ta and W, 0.65. ltoreq. y/(x + y). ltoreq.0.98, 0.35. ltoreq. z.ltoreq.0.5, and x + y + z.1), and a crystal structure thereof is a hexagonal wurtzite-type single phase and a high B constant can be obtained (patent document 8).

In addition, a material is also being developed which is composed of a compound represented by the general formula: (M)_1-wA_w)_xAl_yN_z(wherein M represents at least one of Ti, V, Cr, Mn, Fe and Co, and A represents at least one of Sc, Zr, Mo, Nb and W; 0.0 < W < 1.0, 0.70. ltoreq. y/(x + y). ltoreq.0.98, 0.4. ltoreq. z.ltoreq.0.5, and x + y + z. ltoreq.1), and the crystal structure thereof is a hexagonal wurtzite-type single phase (patent document 9).

Patent document 1: japanese patent laid-open publication No. 2013-179161

Patent document 2: japanese patent laid-open No. 2014-123646

Patent document 3: japanese patent laid-open No. 2014-236204

Patent document 4: japanese patent laid-open publication No. 2015-65408

Patent document 5: japanese patent laid-open publication No. 2015-65417

Patent document 6: japanese patent laid-open publication No. 2015-73077

Patent document 7: japanese patent laid-open publication No. 2015-73075

Patent document 8: japanese patent laid-open publication No. 2016-136609

Patent document 9: japanese patent laid-open publication No. 2015-073075

The above-described conventional techniques still have the following problems.

That is, the metal nitride materials for thermistors described in the above patent documents have a high B constant, and show little change in resistance value and B constant before and after a heat resistance test at 125 ℃.

Disclosure of Invention

The present invention has been made in view of the above-described problems, and an object thereof is to provide a thermistor which has a small change in resistance value before and after a heat resistance test and can obtain a high B constant, a method for manufacturing the thermistor, and a thermistor sensor.

The present invention adopts the following configuration to solve the above problem. That is, a thermistor according to a first aspect of the present invention is a thermistor formed on a substrate, comprising: an intermediate laminated portion formed on the base material: and a main metal nitride film layer formed of a metal nitride thermistor material on the intermediate laminated portion, the intermediate laminated portion being configured by laminating one or more pairs of two layers of a base thermistor layer formed of a metal nitride thermistor material and an intermediate oxynitride layer formed on the base thermistor layer, the main metal nitride film layer being formed on the intermediate oxynitride layer on the uppermost portion of the intermediate laminated portion, the intermediate oxynitride layer being a metal oxynitride layer formed by oxidizing the thermistor material of the base thermistor layer directly below.

In this thermistor, the intermediate oxynitride layer is a metal oxynitride layer formed by oxidizing the thermistor material of the underlying thermistor layer directly below, and the intermediate oxynitride layer can form a good-quality main metal nitride film layer composed of a common element other than oxygen, in the same manner as the underlying thermistor layer, and the intermediate oxynitride layer of the metal oxynitride layer functions as a barrier layer that suppresses the influence of moisture, defects, impurities, or the like in the underlying thermistor layer, and can obtain a main metal nitride film layer with little change in resistance value after a heat resistance test.

A thermistor according to a second aspect of the invention is the thermistor according to the first aspect of the invention, wherein the base thermistor layer and the main metal nitride film layer have the same composition.

That is, in this thermistor, since the base thermistor layer and the main metal nitride film layer have the same composition, the main metal nitride film layer having high crystallinity and high reliability can be formed. By setting the composition ratio a/(M + a) to be the same, the lattice constants of both are the same, and the difference in internal stress between the two layers is extremely small, so that the difference in thermal expansion is extremely small, and higher reliability can be obtained.

A thermistor according to a third aspect of the invention is the thermistor according to the first or second aspect of the invention, wherein the intermediate laminated portion is formed by laminating the base thermistor layer and the intermediate oxynitride layer on the base material repeatedly in this order.

That is, in this thermistor, the intermediate laminated portion is formed by laminating two layers of the base thermistor layer and the intermediate oxynitride layer on the base material in this order and repeatedly a plurality of times, and therefore, the effect as the barrier layer can be further improved.

A thermistor according to a fourth aspect of the invention is characterized in that in any one of the first to third aspects, the base thermistor layer and the main metal nitride film layer have a crystal structure of a hexagonal wurtzite-type single phase, and 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)), M '-Al-N (where M' represents at least one of Zr, Nb, Mo, Hf, A, and W), or G-a '-Al-N (where G represents at least one of Ti, V, Cr, Mn, Fe, and Co, and a' represents at least one of Sc, Zr, Mo, Nb, and W).

That is, in this thermistor, the base thermistor layer and the main metal nitride film layer are 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)), M '-Al-N (where M' represents at least one of Zr, Nb, Mo, Hf, A, and W), or G-a '-Al-N (where G represents at least one of Ti, V, Cr, Mn, Fe, and Co, and a' represents at least one of Sc, Zr, Mo, Nb, and W), and the crystal structure of the main metal nitride film layer is a hexagonal wurtzite-type single phase, so a high B constant can be obtained.

A thermistor according to a fifth aspect of the invention is the fourth aspect of the invention, wherein the base thermistor layer and the main metal nitride film layer are the M-a-N, the M element in the M-a-N is Ti, and the a element is Al.

Namely, the base thermistor layer and the main metal nitride film layer are both Ti-Al-N.

A thermistor according to a sixth aspect of the invention is characterized in that, in any one of the first to fifth aspects, the substrate is an insulating film.

That is, in this thermistor, even if the substrate is an insulating film which is an organic substrate such as polyimide, a favorable main metal nitride film layer can be obtained. Further, since the base material is an insulating thin film, if the base thermistor layer, the intermediate oxynitride layer, and the main metal nitride film layer having flexibility are formed, the entire flexible thermistor can have flexibility and can be used as a flexible thermistor which can be provided in a bent state or the like.

A thermistor according to a seventh aspect of the present invention includes: the thermistor according to any one of the first to sixth inventions; and a pair of opposing electrodes formed on the main metal nitride film layer so as to face each other.

That is, since the thermistor according to any one of the first to sixth aspects is provided in the thermistor sensor, a thermistor sensor having good thermistor characteristics with little change in resistance value even after the heat resistance test can be obtained.

A method of manufacturing a thermistor according to an eighth aspect of the invention is the method of manufacturing any one of the first to sixth aspects of the invention, the method including: an intermediate laminated part forming step of forming an intermediate laminated part on the base material; a main metal nitride film layer forming step of forming the main metal nitride film layer from a thermistor material of a metal nitride on the intermediate laminated portion, the intermediate laminated part forming step is configured by repeating two steps of the base thermistor layer forming step and the intermediate oxynitride layer forming step one or more times, the base thermistor layer is formed of a thermistor material of metal nitride in the base thermistor layer forming step, in the intermediate oxynitride layer forming step, an intermediate oxynitride layer is formed on the base thermistor layer, in the primary metal nitride film layer forming step, the primary metal nitride film layer is formed on the uppermost intermediate oxynitride layer of the intermediate laminated part, in the intermediate oxynitride layer forming step, the intermediate oxynitride layer is formed by oxidizing the surface of the base thermistor layer.

That is, in this method for manufacturing a thermistor, since the intermediate oxynitride layer is formed by oxidizing the surface of the base thermistor layer in the intermediate oxynitride layer forming step, it is not necessary to separately prepare a sputtering target or the like and provide a film forming step for the intermediate oxynitride layer, and the intermediate oxynitride layer of the metal oxynitride layer can be easily obtained at low cost.

A method of manufacturing a thermistor according to a ninth aspect of the invention is the eighth aspect of the invention, wherein in the intermediate stacked portion forming step, the two steps of the base thermistor layer forming step and the intermediate oxynitride layer forming step are sequentially repeated a plurality of times.

That is, in this method for manufacturing a thermistor, since the intermediate laminated portion forming step is repeated a plurality of times in this order, the base thermistor layer forming step and the intermediate oxynitride layer forming step can be laminated, and a thermistor having a better barrier layer effect can be manufactured.

According to the present invention, the following effects are exhibited.

That is, according to the thermistor of the present invention, since the intermediate oxynitride layer is a metal oxynitride layer formed by oxidizing the thermistor material of the underlying thermistor layer directly below, it is possible to form a high-quality main metal nitride layer composed of a general-purpose element other than oxygen, in the same manner as the underlying thermistor layer, with the intermediate oxynitride layer of the metal oxynitride layer functioning as a barrier layer that suppresses the influence of moisture, defects, impurities, or the like in the underlying thermistor layer, and to obtain a main metal nitride layer with little change in resistance value after the heat resistance test.

Therefore, when the heat resistance test is performed, the influence of moisture, defects, impurities, or the like in the base thermistor layer on the main metal nitride film layer is suppressed by the intermediate oxynitride layer, and the change in resistance value before and after the heat resistance test can be further suppressed as compared with the case where the main metal nitride film layer is formed directly on the base material.

Further, according to the method for manufacturing a thermistor of the present invention, since the intermediate oxynitride layer forming step oxidizes the surface of the base thermistor layer to form the intermediate oxynitride layer, it is not necessary to separately prepare a sputtering target or the like and provide a film forming step for the intermediate oxynitride layer, and the intermediate oxynitride layer of the metal oxynitride layer can be easily obtained at low cost.

Further, according to the thermistor sensor of the present invention, since the thermistor of the present invention is provided, a thermistor sensor having excellent thermistor characteristics with little change in resistance value even after a heat resistance test can be obtained.

Drawings

Fig. 1 is a cross-sectional view showing a thermistor according to a first embodiment of the thermistor, a method of manufacturing the thermistor, and a thermistor sensor according to the present invention.

Fig. 2 is a front view and a plan view showing a thermistor sensor and a film evaluation element in the present embodiment and an example according to the present invention.

Fig. 3 is a graph showing a change rate of a resistance value at 25 ℃ after a heat resistance test at 250 ℃ in the thermistor, the method for manufacturing the same, and the thermistor sensor according to the present invention, and the comparative examples.

Fig. 4 is a cross-sectional TEM image showing a thermistor in an example according to the present invention.

FIG. 5 is an HAADF image showing a cross section of a thermistor and TEM-EDS images of oxygen, nitrogen, Al, and Ti in examples according to the present invention.

Fig. 6 is a cross-sectional view showing a thermistor according to a second embodiment of the thermistor, the method of manufacturing the thermistor, and the thermistor sensor of the present invention.

Detailed Description

A thermistor, a method for manufacturing the same, and a first embodiment of a thermistor sensor according to the present invention will be described below with reference to fig. 1 and 2. In the drawings used in the following description, the scale is appropriately changed as necessary in order to make each portion a recognizable or easily recognizable size.

As shown in fig. 1, the thermistor 1 of the present embodiment is a thermistor formed on a substrate 2, and includes an intermediate laminated portion 7 formed on the substrate 2, and a main metal nitride film layer 4 formed of a thermistor material of metal nitride on the intermediate laminated portion 7.

The intermediate laminated portion 7 is formed by laminating a pair of two layers, i.e., a base thermistor layer 3 and an intermediate oxynitride layer 3a, the base thermistor layer 3 being formed of a thermistor material of metal nitride, and the intermediate oxynitride layer 3a being formed on the base thermistor layer 3.

The main metal nitride film layer 4 is formed on the intermediate oxynitride layer 3a, and the intermediate oxynitride layer 3a is a metal oxynitride layer formed by oxidizing the thermistor material of the underlying thermistor layer 3 directly below.

The base thermistor layer 3 and the main metal nitride film layer 4 are 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)), M '-Al-N (where M' represents at least one of Zr, Nb, Mo, Hf, A, and W), or G-a '-Al-N (where G represents at least one of Ti, V, Cr, Mn, Fe, and Co, and a' represents at least one of Sc, Zr, Mo, Nb, and W).

The crystal structure of the main metal nitride film layer 4 is a hexagonal wurtzite-type single phase.

The intermediate oxynitride layer 3a is a metal oxynitride layer formed by oxidizing the thermistor material of the underlying thermistor layer 3 directly below. That is, the intermediate oxynitride layer 3a is an oxide layer of 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)), M '-Al-N (where M' represents at least one of Zr, Nb, Mo, Hf, A, and W), or G-a '-Al-N (where G represents at least one of Ti, V, Cr, Mn, Fe, and Co, and a' represents at least one of Sc, Zr, Mo, Nb, and W). In the present embodiment, the intermediate oxynitride layer 3a is formed by oxidizing the surface of the underlying thermistor layer 3 directly below. That is, the base thermistor layer 3 of the present embodiment is an initial film formation layer for forming the intermediate oxynitride layer 3 a.

The thickness of the base thermistor layer 3 is preferably 6 to 10 nm.

The thickness of the intermediate oxynitride layer 3a is about 1 nm.

The thickness of the main metal nitride film layer 4 is, for example, 90 nm.

In the present embodiment, the base thermistor layer 3 and the main metal nitride film layer 4 are composed of metal nitrides as follows: in the general formula: m_xA_yN_z(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 metal nitride represented by 0.70. ltoreq. y/(x + y). ltoreq.0.98, 0.4. ltoreq. z.ltoreq.0.5, and x + y + z. ltoreq.1); in the general formula: m'_xAl_yN_z(wherein M' represents at least one of Zr, Nb, Mo, Hf, Ta and W, 0.65. ltoreq. y/(x + y). ltoreq.0.98, 0.35. ltoreq. z.ltoreq.0.5, and x + y + z.ltoreq.1); or in the general formula: (G)_1-wA’_w)_xAl_yN_z(wherein G represents at least one of Ti, V, Cr, Mn, Fe and Co, and A' represents at least one of Sc, Zr, Mo, Nb and W; 0.0 < W < 1.0, 0.70. ltoreq. y/(x + y). ltoreq.0.98, 0.4. ltoreq. z.ltoreq.0.5, and x + y + z.ltoreq.1).

In addition, the base thermistor layer 3 has conductivity and exhibits thermistor characteristics.

The crystal structure of the main metal nitride film layer 4 is a hexagonal wurtzite structure (space group P6) as described above₃mc (No.186)) is a film having thermistor characteristics. A is Al or (Al and Si), that is, Al or Al and Si, and includes at least Al.

The main metal nitride film layer 4 has a crystal orientation with a large c-axis orientation degree in a direction perpendicular to the substrate surface (film thickness direction). The crystalline phase was identified by Grazing Incidence X-ray diffraction (Grazing Incidence X-ray diffraction), with the tube sphere set to Cu and the angle of Incidence set to 1 degree. Further, regarding the judgment of whether the a-axis orientation (100) is strong or the c-axis orientation (002) is strong in the direction perpendicular to the film surface (film thickness direction), the orientation of the crystal axis was investigated using the above-mentioned X-ray diffraction (XRD), and the c-axis orientation was considered strong when the peak intensity of "(100)"/"the peak intensity of (002)" is less than 1, based on the peak intensity ratio of (100) (hkl index indicating the a-axis orientation) to (002) (hkl index indicating the c-axis orientation). When TEM (transmission electron microscope) is used, it can be confirmed that the c-axis orientation degree in the film thickness direction of the main metal nitride film layer 4 is high by acquiring an electron beam diffraction image of the film cross section.

The main metal nitride film layer 4 is a dense columnar crystal film. This can be confirmed by evaluation of the crystal morphology by cross-section SEM or cross-section TEM.

The base thermistor layer 3 and the main metal nitride film layer 4 are preferably the same in composition.

In the present embodiment, for example, the base thermistor layer 3 and the main metal nitride film layer 4 are the M-a-N, the M element in the M-a-N is Ti, and the a element is Al. In particular, the base thermistor layer 3 and the main metal nitride film layer 4 are formed of a material represented by the general formula: ti_xAl_yN_z(0.70. ltoreq. y/(x + y). ltoreq.0.95, 0.4. ltoreq. z.ltoreq.0.5, and x + y + z.ltoreq.1).

In addition, M is the crystallinity of the main metal nitride film layer 4_xA_yN_zIf the above "y/(x + y)" (i.e., a/(M + a)) is less than 0.70, a wurtzite-type single phase cannot be obtained, and a cocrystal phase with an NaCl-type phase or a crystal phase of NaCl-type only cannot be obtained, resulting in a sufficiently high resistance and a high B constant.

When the "y/(x + y)" (i.e., a/(M + a)) exceeds 0.98, the resistivity is very high and the insulation is extremely high, and therefore, the material cannot be used as a thermistor material.

When "z" (i.e., N/(M + a + N)) is less than 0.4, the amount of metal nitriding is small, and therefore a wurtzite-type single phase cannot be obtained, and a sufficiently high resistance and a high B constant cannot be obtained.

When "z" (i.e., N/(M + a + N)) exceeds 0.5, a wurtzite-type single phase cannot be obtained. This is because the stoichiometric ratio when there is no defect at the nitrogen site in the wurtzite-type single phase is 0.5 (i.e., N/(M + a + N) ═ 0.5).

The crystal phase was identified by Grazing Incidence X-ray diffraction (Grazing Incidence X-ray diffraction), and the tube sphere was Cu and the Incidence angle was 1 degree.

As described above, the wurtzite-type crystal structure is the hexagonal space group P6₃mc (No.186), M and a belong to the same atomic site (M represents at least one of Ti, V, Cr, Mn, Fe, Co, Ni and Cu, and a represents Al or (Al and Si)), and are in a so-called solid solution state. The wurtzite form employs (M, A) a vertex-linked structure of N4 tetrahedron, the closest site of (M, A) site is N (nitrogen), and (M, A) employs nitrogen tetradentate.

In addition to Ti, V (vanadium), Cr (chromium), Mn (manganese), Fe (iron), Co (cobalt), Ni (nickel), and Cu (copper) can be present at the same atomic site as Ti in the crystal structure, and can be an M element. The effective ionic radius is a physical property value used by grasping the distance between atoms, and when a well-known literature value of ionic radius of Shannon is used, it can be theoretically estimated that wurtzite-type M can be obtained_xA_yN_z(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 effective ionic radii in the individual ionic species of Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Si are shown in table 1 below (see article r.d. shannon, Acta crystalloger, sect.a,32,751(1976)) (r.d. shannon, part a of the crystal thesis, 32,751 (1976)).

[ Table 1]

Effective ionic radius

Reference paper r.d. shannon, Acta crystallogr, sect.a,32,751(1976)

The wurtzite form is quadridentate, and when M is observed about the effective ionic radius of the quadridentate form, Ni < Cu < Co < Fe < Mn > in the case of valency 2, Al < Fe < Mn >, in the case of valency 3, Mn < Co < Cr < Ti in the case of valency 4, and Cr < V in the case of valency 5, it is considered that (Al, Cu, Co, Fe, Ni, Mn) < Cr < (V, Ti) (the relationship of the ionic radii of Ti and V or Cu, Co, Fe, Ni, Mn, and Al cannot be determined), however, since the valences of the four coordinative data are different from each other, a strict comparison cannot be made, and thus, data of a six-coordinate (MN6 octahedron) fixed to a 3-valent ion as a reference is used for comparison, HS in Table 1 represents a high spin state, L S represents a low spin state, and when it is in a low spin state (L S), the ionic radius of Cu < Al < Fe < Ni < Mn < Ni < Fe, and when Mn is greater than that of Ti < Ni < Fe, Ni < Fe < Ni < Fe, Mn < Fe

Although the thermistor characteristics can be obtained by substituting M such as Ti for Al sites of crystalline Al — N, which is a nitride insulator having a wurtzite crystal structure, to obtain carrier doping, the present invention increases the conductivity, but, for example, when the Al sites are substituted to Ti, the effective ion radius of Ti is larger than that of Al, and as a result, the average ion radius of Al and Ti increases. As a result, it is presumed that the interatomic distance increases and the lattice constant increases.

Actually, in patent documents 2 to 7, wurtzite-type M can be obtained_xA_yN_z(wherein M represents at least one of Ti, V, Cr, Mn, Fe, Co, Ni and Cu, and A represents Al or (Al and Si)), and thermistor characteristics can be obtained. Further, the following reports are given: it was confirmed from the X-ray data that the lattice constant increased by replacing the Al site of crystalline Al — N with Ti or the like. In addition, the following reports are reported: as to Si, Si andthe magnitude of the ionic radius of Al, but in patent document 5, M containing both Al and Si_xA_yN_zHas a wurtzite crystal structure, and thus, thermistor characteristics can be obtained.

And M 'as a crystalline property of the main metal nitride film layer 4'_xAl_yN_zIf the above "y/(x + y)" (i.e., Al/(M '+ Al)) is less than 0.65, a wurtzite-type single phase cannot be obtained, and a part of M' element becomes a intergrown phase with the NaCl-type phase or a crystal phase of NaCl only, and a sufficiently high resistance and a high B constant cannot be obtained.

If the "y/(x + y)" (i.e., Al/(M' + Al)) exceeds 0.98, the resistivity is very high and the insulation is extremely high, and therefore, the material cannot be used as a thermistor material.

If "z" (i.e., N/(M' + Al + N)) is less than 0.35, the amount of metal nitriding is small, and therefore a wurtzite-type single phase cannot be obtained, and a sufficiently high resistance and a high B constant cannot be obtained.

If "z" (i.e., N/(M' + Al + N)) exceeds 0.5, a wurtzite-type single phase cannot be obtained. This is because the stoichiometric ratio when there is no defect at the nitrogen site in the wurtzite-type single phase is 0.5 (i.e., N/(M' + Al + N) ═ 0.5).

In fact, in patent document 8, the zinc sulfide is formed of wurtzite-type M'_xAl_yN_z(wherein M' represents at least one of Zr, Nb, Mo, Hf, Ta and W, 0.65. ltoreq. y/(x + y). ltoreq.0.98, 0.35. ltoreq. z.ltoreq.0.5, and x + y + z.1) is preferable because it can provide a thermistor characteristic having a good B constant without firing.

The crystallinity of the main metal nitride film layer 4 is (G)_1-wA’_w)_xAl_yN_zIf the above "y/(x + y)" (i.e., Al/(G + a' + Al)) is less than 0.70, a wurtzite-type single phase cannot be obtained, and a cocrystal phase with an NaCl-type phase or a crystal phase of NaCl-type only cannot be obtained, and thus a sufficiently high resistance and a high B constant cannot be obtained.

If the "y/(x + y)" (i.e., Al/(G + a' + Al)) exceeds 0.98, the resistivity is very high and the insulation is extremely high, and therefore, the material cannot be used as a thermistor material.

When the "z" (i.e., N/(G + a' + Al + N)) is less than 0.4, the amount of metal nitriding is small, and therefore a wurtzite-type single phase cannot be obtained, and a sufficiently high resistance and a high B constant cannot be obtained.

When the "z" (i.e., N/(G + a' + Al + N)) exceeds 0.5, a wurtzite-type single phase cannot be obtained. This is because the stoichiometric ratio when there is no defect at the nitrogen site in the wurtzite-type single phase is 0.5 (i.e., N/(G + a' + Al + N) ═ 0.5).

In addition, in practice, patent document 9 discloses a zinc oxide-containing alloy made of wurtzite (G)_1-wA’_w)_xAl_yN_z(wherein G represents at least one of Ti, V, Cr, Mn, Fe and Co, and A' represents at least one of Sc, Zr, Mo, Nb and W; 0.0 < W < 1.0, 0.70. ltoreq. y/(x + y). ltoreq.0.98, 0.4. ltoreq. z.ltoreq.0.5, and x + y + z 1), the resulting metal nitride can exhibit a thermistor characteristic that is non-fired and has a good B constant.

The substrate 2 is an insulating film such as polyimide. Further, as the insulating film, a film made of PET: polyethylene terephthalate, PEN: polyethylene naphthalate and the like, but flexibility and heat resistance are required. For example, as a temperature for measuring the fixing roller, the maximum use temperature is about 200 ℃. In recent years, polyimide films having extremely excellent heat resistance, which can be used even at temperatures of 200 ℃ or higher, have been developed.

Next, a thermistor sensor using the thermistor according to the present embodiment will be described. As shown in fig. 2, the thermistor sensor 10 includes a base material 2 of a thermistor 1, an intermediate laminated portion 7 (an underlying thermistor layer 3, an intermediate oxynitride layer 3a), a main metal nitride film layer 4, and a pair of opposing electrodes 5 formed on the main metal nitride film layer 4 so as to face each other.

The pair of counter electrodes 5 are patterned from, for example, a laminated metal film of a Cr film and an Au film, and are formed in a comb-shaped pattern having a plurality of comb portions 5a in a state of facing each other on the main metal nitride film layer 4.

A method of manufacturing the thermistor 1 and a method of manufacturing the thermistor sensor 10 using the method will be described below.

The method of manufacturing the thermistor 1 of the present embodiment includes: an intermediate laminated portion forming step of forming an intermediate laminated portion 7 on the base material 2; and a main metal nitride film layer forming step of forming a main metal nitride film layer 4 of a thermistor material of metal nitride on the intermediate laminated part 7.

The intermediate laminated portion forming step is composed of two steps, i.e., a base thermistor layer forming step of forming the base thermistor layer 3 from a thermistor material of a metal nitride, and an intermediate oxynitride layer forming step of forming the intermediate oxynitride layer 3a on the base thermistor layer 3.

In the main metal nitride film layer forming step, a main metal nitride film layer is formed on the intermediate oxynitride layer 3a, and in the intermediate oxynitride layer forming step, the surface of the base thermistor layer 3 is oxidized to form the intermediate oxynitride layer 3 a.

In order to form the base thermistor layer 3 and the main metal nitride film layer 4 which become the intermediate laminated portion 7, a metal nitride film having thermistor characteristics is formed by, for example, a reactive sputtering method in a nitrogen-containing atmosphere. The film thickness at this time is set to 100nm, for example, in total, before the surface is oxidized, of the base thermistor layer 3 and the main metal nitride film layer 4.

For example, when M is Ti and a is Al, the sputtering conditions in this case are, for example, a Ti — Al alloy sputtering target having a composition ratio Al/(Al + Ti) of 0.85 and a limiting vacuum degree of 4 × 10^-5Pa, sputtering gas pressure: 0.2Pa, target input power (output): 200W, nitrogen partial pressure under a mixed gas atmosphere of Ar gas and nitrogen: 30 percent.

In the base thermistor layer forming step, the base thermistor layer 3 is formed to have a film thickness of, for example, 10nm, and in the intermediate oxynitride layer forming step, the surface of the base thermistor layer 3 is oxidized by, for example, a natural oxidation treatment for 5 minutes in air at room temperature to form the intermediate oxynitride layer 3a having a thickness of about 1 nm. The intermediate oxynitride layer 3a is formed by oxidizing the surface of the base thermistor layer 3 made of metal nitride, and is therefore a metal oxynitride layer.

As the oxidation treatment method, a heat treatment at 150 ℃ or the like may be used in air.

Then, in the primary metal nitride film layer forming step, the primary metal nitride film layer 4 having a film thickness of 90nm is formed again under the same sputtering conditions as in the base thermistor layer forming step.

In the case of manufacturing the thermistor sensor 10 according to the present embodiment, a Cr film of 20nm, for example, and an Au film of 200nm are formed on the main metal nitride film layer 4 by a sputtering method. Further, after the resist liquid was applied thereon with a bar coater, prebaking was performed at 110 ℃ for 1 minute and 30 seconds, after sensitization was performed with an exposure device, unnecessary portions were removed with a developing solution, and patterning was performed by postbaking at 150 ℃ for 5 minutes. Then, the unnecessary electrode portions are wet-etched with a commercially available Au etchant and Cr etchant, and the resist is stripped off to form the counter electrodes 5 having the desired comb portions 5a, as shown in fig. 2. The thermistor sensor 10 of the present embodiment is thus manufactured.

As described above, in the thermistor 1 of the present embodiment, since the intermediate oxynitride layer 3a is a metal oxynitride layer formed by oxidizing the thermistor material of the underlying thermistor layer 3 directly below, the intermediate oxynitride layer 3a can form the high-quality main metal nitride film layer 4 made of a common element other than oxygen, similarly to the underlying thermistor layer 3, and the intermediate oxynitride layer 3a of the metal oxynitride layer functions as a barrier layer that suppresses the influence of moisture, defects, impurities, or the like in the underlying thermistor layer 3, and the main metal nitride film layer 4 with little change in resistance value after the heat resistance test can be obtained.

Therefore, when the heat resistance test is performed, the influence of moisture, defects, impurities, or the like in the base thermistor layer 3 on the main metal nitride film layer is suppressed by the intermediate oxynitride layer 3a, and the resistance value change can be further suppressed as compared with the case where the main metal nitride film layer 4 is directly formed on the base material 2.

Further, by making the base thermistor layer 3 and the main metal nitride film layer 4 have the same composition, a highly crystalline and highly reliable main metal nitride film layer can be formed. By setting the composition ratio a/(M + a) to be the same, the lattice constants of both are the same, and the difference in internal stress between the two layers is extremely small, so that the difference in thermal expansion is extremely small, and higher reliability can be obtained.

The base thermistor layer 3 and the main metal nitride film layer 4 are 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)), M '-Al-N (where M' represents at least one of Zr, Nb, Mo, Hf, A, and W), or G-a '-Al-N (where G represents at least one of Ti, V, Cr, Mn, Fe, and Co, and a' represents at least one of Sc, Zr, Mo, Nb, and W), and the crystal structure of the main metal nitride film layer is a hexagonal wurtzite-type single phase, and therefore a film with a high B constant can be obtained.

In addition, even if the substrate 2 is an insulating film which is an organic substrate such as polyimide, a favorable main metal nitride film layer 4 can be obtained. The base thermistor layer 3, the intermediate nitrided oxide layer 3a, and the main metal nitrided film layer 4, which are flexible when the base material 2 is formed as an insulating thin film, can have flexibility as a whole, and can be used as a flexible thermistor that can be placed in a bent state or the like.

By using a polyimide film having extremely excellent heat resistance which can be used at a temperature of 200 ℃ or higher, a flexible thermistor sensor which can be used at a temperature of 200 ℃ or higher can be obtained.

Since the thermistor 1 is provided in the thermistor sensor 10 of the present embodiment, a thermistor sensor having a small change in resistance value, a high B constant, and good thermistor characteristics can be obtained even after the heat resistance test.

In the method for manufacturing a thermistor according to the present embodiment, since the intermediate oxynitride layer forming step oxidizes the surface of the base thermistor layer 3 to form the intermediate oxynitride layer 3a, it is not necessary to separately prepare a sputtering target or the like and provide a film forming step for the intermediate oxynitride layer, and the intermediate oxynitride layer 3a of the metal oxynitride layer can be easily obtained at low cost.

Since the surface oxidation temperature of the base thermistor layer 3 may be 200 ℃ or lower, an insulating film, which is an organic substrate such as polyimide, can be used as the substrate 2.

Next, a second embodiment of the thermistor and the method for manufacturing the same according to the present invention will be described below with reference to fig. 6. In the following description of the embodiments, the same components as those described in the above embodiments are denoted by the same reference numerals, and the description thereof is omitted.

The second embodiment differs from the first embodiment in that the intermediate laminated portion 7 is formed by laminating the base thermistor layer 3 and the intermediate oxynitride layer 3a one by one in the first embodiment, but in the thermistor 21 and the manufacturing method thereof of the second embodiment, as shown in fig. 6, the intermediate laminated portion 27 is formed by laminating two layers of the base thermistor layer 3 and the intermediate oxynitride layer 3a on the base material 2 in a plurality of times in sequence.

That is, in the second embodiment, the main metal nitride film layer 4 is formed on the uppermost intermediate oxynitride layer 3a of the intermediate laminated portion 27.

In the second embodiment, the intermediate laminated portion forming step is configured by repeating two steps of the base thermistor layer forming step and the intermediate oxynitride layer forming step a plurality of times.

For example, as shown in fig. 6, an intermediate laminated portion 27 is formed by repeatedly laminating two layers of the base thermistor layer 3 and the intermediate oxynitride layer 3a twice. That is, the intermediate laminated portion 27 has a 4-layer structure in which the base thermistor layer 3, the intermediate oxynitride layer 3a, the base thermistor layer 3, and the intermediate oxynitride layer 3a are laminated in this order on the base material 2.

The intermediate laminated portion may be formed by repeatedly laminating two layers of the base thermistor layer 3 and the intermediate oxynitride layer 3a 3 times or more. In this case, the intermediate laminated portion 27 has a 6-layer structure composed of 3 base thermistor layers 3 and 3 intermediate oxynitride layers 3a laminated on the base material 2.

In this way, in the thermistor 21 and the method of manufacturing the same according to the second embodiment, the intermediate laminated portion 27 is configured by laminating two layers of the base thermistor layer 3 and the intermediate oxynitride layer 3a on the base material 2 repeatedly in this order a plurality of times, and therefore the effect as a barrier layer can be further improved.