Metal nitride material for thermistor, method for producing same, and film type thermistor sensor
09625326 ยท 2017-04-18
Assignee
Inventors
Cpc classification
C30B29/605
CHEMISTRY; METALLURGY
International classification
H01C7/00
ELECTRICITY
Abstract
The metal nitride material for a thermistor consists of a metal nitride represented by the general formula: (M.sub.1-.sub.vA.sub.v).sub.xAl.sub.y(N.sub.1-wO.sub.w).sub.z (where M represents at least one of Ti, V, Cr, Mn, Fe, and Co, A represents at least one of Sc, Zr, Mo, Nb, and W, 0.0<v<1.0, 0.70y/(x+y)0.98, 0.45z0.55, 0<w0.35, and x+y+z=1), wherein the crystal structure thereof is a hexagonal wurtzite-type single phase.
Claims
1. A metal nitride material for a thermistor, consisting of a metal nitride represented by the general formula: (M.sub.1-vA.sub.v).sub.xAl.sub.y(N.sub.1-wO.sub.w).sub.z (where M represents at least one of Ti, V, Cr, Mn, Fe, and Co, A represents at least one of Sc, Zr, Mo, Nb, and W, 0.0<v<1.0, 0.70y/(x+y) 0.98, 0.45z0.55, 0w0.35, and x+y+z=1), wherein the crystal structure thereof is a hexagonal wurtzite-type single phase.
2. The metal nitride material for a thermistor according to claim 1, wherein the metal nitride material, is deposited as a film and is a columnar crystal, extending in a vertical direction with respect to the surface of the film.
3. The metal nitride material for a thermistor according to claim 2, wherein the metal nitride material is deposited as a film and is more strongly oriented along a c-axis than an a-axis in a vertical direction with respect to the surface of the film.
4. A film type thermistor sensor comprising: an insulating film; a thin film thermistor portion made of the metal nitride material for a thermistor according to claim 2 on the insulating film; and a pair of pattern electrodes formed at least on the top or the bottom of the thin film thermistor portion.
5. A method for producing the metal nitride material for a thermistor according to claim 2, the method comprising: a deposition step of performing film deposition by reactive sputtering in a nitrogen- and oxygen-containing atmosphere using an M-A-Al (where 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) alloy sputtering target.
6. The metal nitride material, for a thermistor according to claim 1, wherein the metal nitride material is deposited as a film and is more strongly oriented along a c-axis than, an a-axis in a vertical direction with respect to the surface of the film.
7. A film type thermistor sensor comprising: an insulating film; a thin film thermistor portion made of the metal nitride material for a thermistor according to claim 6 on the insulating film; and a pair of pattern electrodes formed at least on the top or the bottom of the thin film thermistor portion.
8. A film type thermistor sensor comprising: an insulating film; a thin film thermistor portion made of the metal nitride material for a thermistor according to claim 1 on the insulating film; and a pair of pattern electrodes formed at least on the top or the bottom of the thin firm thermistor portion.
9. A method for producing the metal nitride material for a thermistor according to claim 6, the method comprising: a deposition step of performing film deposition by reactive sputtering in a nitrogen- and oxygen-containing atmosphere using an M-A-Al (where 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 alloy sputtering target.
10. A method for producing the metal nitride material for a thermistor according to claim 1, the method comprising: a deposition step of performing film deposition by reactive sputtering in a nitrogen- and oxygen-containing atmosphere using an M-A-Al (where 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) alloy sputtering target.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
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DESCRIPTION OF THE EMBODIMENTS
(29) Hereinafter, a description will be given of a metal nitride material for a thermistor, a method for producing the same, and a film type thermistor sensor according to one embodiment of the present invention with reference to
(30) The metal nitride material for a thermistor of the present embodiment consists of a metal nitride represented by the general formula: (M.sub.1-vA.sub.v).sub.xAl.sub.y(N.sub.1-wO.sub.z (where M represents at least one of Ti, V, Cr, Mn, Fe, and Co, A represents at least one of Sc, Zr, Mo, Nb, and W, 0.0<v<1.0, 0.70y/(x+y)0.98, 0.45z0.55, 0<w0.35, and x+y+z=1), wherein the crystal structure thereof is a hexagonal wurtzite-type (space group: P6.sub.3mc (No. 186)) single phase.
(31) For example, in the case where M=Ti, A=Sc, the metal nitride material for a thermistor of the present embodiment consists of a metal nitride represented by the general formula: (Ti.sub.1-vSc.sub.v).sub.xAl.sub.y(N.sub.1-wO.sub.w).sub.z (where 0.0<v <1.0, 0.70y/(x+y)0.98, 0.45z0.55, 0<w0.35, and x+y+z=1), wherein the crystal structure thereof is a hexagonal wurtzite-type single phase. Specifically, the metal nitride material for a thermistor consists of a metal nitride having a composition within the region enclosed by the points A, B, C, and D in the (Ti+Sc (scandium))-Al-(N+O)-based ternary phase as shown in
(32) In the case where M=Ti, A=Zr, the metal nitride material for a thermistor of the present, embodiment consists of a metal nitride represented try the general formula: (Ti.sub.1-vZr.sub.vZr.sub.v).sub.xAl.sub.y(N.sub.1-wO.sub.w).sub.z (where 0.0<v<1.0, 0.70y/(x+y)0.98, 0.45z0.55, 0<w0.35, and x+y+z=1), wherein the crystal structure thereof is a hexagonal wurtzite-type single phase. Specifically, the metal nitride material for a thermistor consists of a metal nitride having a composition within the region enclosed by the points A, B, C, and D in the (Ti+Zr (zirconium)-Al(N+O)-based ternary phase diagram as shown in
(33) In the case where M=Ti, A=Mo, the metal nitride material for a thermistor of the present embodiment consists of a metal nitride represented by the general formula: (Ti.sub.1-vMo.sub.v).sub.xAl.sub.y(N.sub.1-wO.sub.w).sub.z (where 0.0<v<1.0, 0.70y/(x+y)0.98, 0.45z0.55, 0<w0.35, and x+y+z=1), wherein the crystal structure thereof is a hexagonal wurtzite-type single phase. Specifically, the metal nitride material for a thermistor consists of a metal nitride having a composition within the region enclosed by the points A, B, C, and D in the (Ti+Mo (molybdenum))-Al(N+O)-based ternary phase diagram as shown in
(34) In the case where M=Ti, A=Nb, the metal nitride material for a thermistor of the present embodiment consists of a metal nitride represented by the general formula: (Ti.sub.1-vNb.sub.v).sub.xAl.sub.y(N.sub.1-wO.sub.w).sub.z (where 0.0<v<1.0, 0.70y/(x+y)0.98, 0.45z0.55, 0<w0.35, and x+y+z=1), wherein the crystal structure thereof is a hexagonal wurtzite-type single phase. Specifically, the metal nitride material for a thermistor consists of a metal nitride having a composition within the region enclosed by the points A, B, C, and D in the Ti+Nb (niobium))-Al(N+O)-based ternary phase diagram as shown in
(35) In the case where M=Ti, A=W, the metal nitride material for a thermistor of the present embodiment consists of a metal nitride represented by the general formula: (Ti.sub.1-vW.sub.v).sub.xAl.sub.y(N.sub.1-wO.sub.w).sub.z (where 0.0<v<1.0, 0.70y/(x+y)0.98, 0.45z0.55, 0<w0.35, and x+y+z=1), wherein the crystal structure thereof is a hexagonal wurtzite-type single phase. Specifically, the metal nitride material for a thermistor consists of a metal nitride having a composition within the region enclosed by the points A, B, C, and D in the (Ti+W (tungsten))-Al(N+O)-based ternary phase diagram as shown in
(36) Note that the composition ratios or (x, y, z) (at %) at the points A, B, C, and D are A (x, y, z=13.5, 31.5, 55.0), 8 (x, y, z=0.9, 44.1, 55.0), C (x, y, z=1.1, 53.9, 45.0), and D (x, y, z=16.3, 38.5, 45.0), respectively.
(37) As described above, the wurtzite-type crystal structure belongs to the hexagonal space group of P6.sub.3mc (No. 186), and Ti, A, and Al (where A represents at least one of Sc, Zr, Mo, Nb and W) are present at the same atomic site, that is, they are in a so-called solid solution for example, in the case of Ti.sub.0.08Mo.sub.0.02Al.sub.0.9N, Ti, Mo, and Al are present at the same atomic site with the probability of 8%, 2%, and 90%, respectively). The wurtzite-type crystal structure is a structure in which the vertexes of (Ti, A, Al) N.sub.4 tetrahedron are connected each other and the nearest-neighbor site of the (Ti, A, Al) site is N (nitrogen), whereby (Ti, A, Al) is four-coordinated by nitrogen.
(38) Note that, other than Ti, V (vanadium), Cr (chromium), Mn (manganese) , Fe (iron) , and Co (cobalt can also be present at the same atomic site as Ti in the above crystal structure, and can be an element of M. The effective ionic radius is a physical property that is often used in order to determine the interatomic distance. In particular, using well known literature values for the ionic radius by Shannon, it is logically assumed that a wurtzite-type (V, A)AlNO, (Cr, A)AlNO, (Mn, A)AlNO, (Fe, A) AlNO, and (Co, A)AlNO (where A represents at least: one of Sc, Zr, Mo, Nb, and W) structure can be obtained. Here, the oxygen (O) is oxygen that compensates nitrogen defects in a crystal or is interstitial oxygen.
(39) Table 1 shows the effective ionic radius of each ion species of Al, Ti, V, Cr, Mn, Fe, and Co (ref., R, D. Shannon, Acta Crysta.) logr. , Sect, A, 32, 751 (1976)).
(40) TABLE-US-00001 TABLE 1 UNIT: nm FOUR-COORDINATED SIX-COORDINATED STRCUTURE STRCUTURE (REFERENCE) ION IONIC ION IONIC SPECIES RADIUS SPECIES RADIUS Al.sup.3+ 0.039 Al.sup.3+ 0.0535 Ti.sup.4+ 0.042 Ti.sup.3+ 0.067 V.sup.5+ 0.0355 V.sup.3+ 0.064 Cr.sup.4+ 0.041 Cr.sup.3+ 0.0615 Cr.sup.5+ 0.0345 Mn.sup.2+ 0.066 Mn.sup.3+ (HS) 0.0645 Mn.sup.4+ 0.039 Mn.sup.5+ 0.033 Mn.sup.3+ (LS) 0.058 Fe.sup.2+ 0.063 Fe.sup.3+ (HS) 0.0645 Fe.sup.3+ 0.049 Fe.sup.3+ (LS) 0.055 Co.sup.2+ 0.058 Co.sup.3+ (HS) 0.061 Co.sup.4+ 0.04 Co.sup.3+ (LS) 0.0545
(41) The wurtzite-type crystal structure exhibits a four-coordinated structure. Referring to the effective ionic radius relative to M regarding the four-coordinated structure, the order of the effective ionic radius is Co<Fe<Mn in the case of divalent ions, Al<Fe in the case of trivalent ions, Mn<Cr<Ti in the case of tetravalent ions, and Cr<V in the case of pentavalent ions. From these results, it is contemplated that (Al, Co)<Fe<Mn<Cr<(V, Ti) (the size relationships of the ionic radius between Ti and V or Co and Al cannot be determined). However, since the valences in the data regarding the four-coordinated structure are different from each other, their precise comparison is impossible. Then, referring to the data regarding the six-coordinated structure (i.e., MN.sub.6 octahedron) in which the valences are fixed so as to be trivalent, it is found that the order of the ionic radius is Al<Co<Fe<Mo<Cr<V<Ti (in Table 1, HS denotes a high-spin state and LS denotes a low-spin state).
(42) The present invention provides an excellent thermistor characteristic by substituting the Al site of AlN, which is an insulator, with Ti or the lake to perform carrier doping, thereby increasing electric conductivity. For example, when the Al site is substituted with Ti, the mean ionic radius between Al and Ti increases because the effective ionic radius of Ti is larger than that of Al. As the result, it is assumed that the atomic distance increases, resulting in the increase of the lattice constant.
(43) The increase of the lattice constant by substituting the Al site of AlN with Ti or the like has been confirmed by X-ray data. Per example, in the X-ray diffraction data described below in the case where M=Ti (
(44) In addition, since the ionic radius of V, Cr, Mn, Fe, and Co falls within a value between Al and Ti, in view of the lattice constant of the wurzite-type crystal structure, it is contemplated that the substitution of the Al site with V, Cr, Mn, Fe, or Co not with Ti can suppress the increase of the lattice constant, when compared by the same substitution amount, which may allow the wurtzite-type crystal structure to be easily managed. Since V, Cr, Mn, Fe, and Co also have a 3d electron(s) and a 4s electron (s) like Ti, carrier doping at the Al site is possible.
(45) Also, the metal nitride material for a thermistor of the present embodiment is deposited as a film, and is a columnar crystal extending in a vertical direction with respect to the surface of the film. Furthermore, it is preferable that the metal, nitride material for a thermistor is more strongly oriented along the c-axis than the a-axis in a vertical direction with respect to the surface of the film.
(46) Note that the decision about whether a moral nitride material for a thermistor has a strong a-axis orientation (100) or a strong c-axis orientation (002) in a vertical direction with respect to the surface or the film is determined by examining the orientation of the crystal axis using X-ray diffraction (XPD). When the peak intensity ratio of the peak intensity of (100)/the peak intensity of (002), where (100) is the hkl index indicating a-axis orientation and (002) is the hkl index indicating c-axis orientation, is less than 1, the metal nitride material for a thermistor is determined to nave a strong c-axis orientation.
(47) Next, a description will be given of a film type thermistor sensor using the metal nitride material for a thermistor of the present embodiment. As shown in
(48) The insulating film 2 is, for example, a polyimide resin sheet formed in a band shape. The insulating film 2 may foe made of another material such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), or the like.
(49) The pair of pattern electrodes 4 has a pair of comb shaped electrode portions 4a that is patterned so as to have a comb shaped pattern by using stacked metal films of, for example, a Cr film and an Au film, and is arranged opposite to each, other on the thin film thermistor portion 3, and a pair of linear extending portions 4b extending with the tip ends thereof being connected to these comb shaped, electrode portions 4a and the base ends thereof being arranged at the end of the insulating film 2.
(50) A plating portion 4c such as Au plating is formed as a lead wire drawing portion on the base end of each of the pair of linear extending portions 4b. One end of the lead wire is joined with the plating portion 4c via a solder material or the like. Furthermore, except for the end of the insulating film 2 including the plating portions 4c, a polyimide coverlay film 5 is pressure bonded onto the insulating film 2. Instead of the polyimide coverlay film 5, a polyimide or epoxy-based resin material layer may be formed onto the insulating film 2 by printing.
(51) A description will be given below of a method for producing the metal nitride material for a thermistor and a method for producing the film type thermistor sensor 1 using the metal nitride material for a thermistor with reference to
(52) Firstly, the method for producing the metal nitride material for a thermistor according to the present embodiment includes a deposition step of performing film deposition by reactive sputtering in a nitrogen- and oxygen-containing atmosphere using an M-A-Al alloy sputtering target (where 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).
(53) For example, a TiScAl alloy sputtering target is employed in the case where M=Ti, A=Sc, a Ti-ZrAl alloy sputtering target is employed in the case where M=Ti, A=Zr, a TiMoAl alloy sputtering target is employed in she case where M=Ti, A=Mo, a TiNbAl alloy sputtering target is employed in the case where M=Ti, A=Nb, and a TiWAl alloy sputtering target is employed in the case where M=Ti, A=W.
(54) It is preferable that a spattering gas pressure during the reactive sputtering is set to less titan 1.5 Pa.
(55) Furthermore, it is preferable that the formed film is irradiated with nitrogen plasma after the deposition step.
(56) More specifically, for example, the thin film thermistor portion 3 having a thickness of 200 nm, which is made of the metal nitride material for a thermistor of the present embodiment, is deposited on the insulating film 2 which is a polyimide film having a thickness of 50 m shown in
(57) For example, the spattering conditions in the case where M=Ti, A=Sc are as follows: an ultimate degree of vacuum; 510.sup.6 Pa, a sputtering gas pressure; 0.67 Pa, a target input power (output) 300 W, and a nitrogen gas partial pressure and an oxygen gas partial pressure under a mixed gas (Ar gas+nitrogen gas oxygen gas) atmosphere: 39.8% and 0.2%, respectively.
(58) For example, the sputtering conditions in the case where M=Ti, A=Zr are as follows: an ultimate degree of vacuum: 510.sup.6 Pa, a sputtering gas pressure: 0.4 Pa, a target input power (output); 300 W and a nitrogen gas partial pressure and an oxygen gas partial pressure trader a mixed gas (Ar gas+nitrogen gas+oxygen gas) atmosphere: 19.8% and 0.2%, respectively.
(59) For example, the sputtering conditions in she case where M=Ti, A=Mo are as follows: an ultimate degree or vacuum: 5/10.sup.6 Pa, a sputtering gas pressure: 0.4 Pa, a target input power (output): 300 W, and a nitrogen gas partial pressure and an oxygen gas partial pressure under a mixed gas (Ar gas+nitrogen gas+oxygen gas) atmosphere: 39.8% and 0.2%, respectively.
(60) For example, the sputtering conditions in the case where M=Ti, A=W are as follows: an ultimate degree of vacuum: 510.sup.6 Pa, a sputtering gas pressure: 0.4 Pa, a target input power (output): 300 W, and a nitrogen gas partial pressure and an oxygen gas partial pressure under a mixed gas (Ar gas e nitrogen gas e oxygen gas) atmosphere: 19.8% and 0.2%, respectively.
(61) For example, the sputtering conditions in the case where M=Ti, A=W are as follows: an ultimate degree of vacuum: 510.sup.6 Pa sputtering gas pressure: 0.4 Pa, a target input power, (output): 300 W and a nitrogen gas partial pressure and an oxygen gas partial pressure under a mixed gas (Ar gas+nitrogen gas+oxygen gas) atmosphere: 19.8% and 0.2%, respectively.
(62) The metal nitride material for a thermistor having a desired size is deposited on the insulating film 2 using a metal mask so as to form the thin film thermistor portion 3. It is preferable that, the formed thin film thermistor portion 3 is irradiated with nitrogen plasma. For example, the thin film thermistor portion 3 is irradiated with nitrogen plasma under the degree of vacuum of 6.7 Pa, the output of 200 W, and the N.sub.2 gas atmosphere.
(63) Next, a Cr film having a thickness of 20 nm is formed and an Au film having a thickness of 200 nm is further formed thereon by the sputtering method, furthermore, a resist solution is coated on the stacked metal films using a barcoater, and then pre-baking is performed for 1.5 minutes at a temperature of 110 C. After being exposed by an exposure device, any unnecessary portion is removed by a developing solution, and then patterning is performed by post-baking for 5 minutes at a temperature of 150 C. Then, any unnecessary electrode portion is subject to wet etching using commercially available Au enchant and Cr etchant, and then the resist is stripped as shown in
(64) Next, as shown in
(65) When a plurality of film type thermistor, sensors 1 is simultaneously produced, a plurality of thin film thermistor portions 3 and a plurality of pattern electrodes 4 are formed on a large-format sheet of the insulating film 2 as described above, and then, the resulting large-format, sheet, is cut into a plurality of segments so as to obtain a plurality of film type thermistor sensors 1.
(66) In this manner, a thin film type thermistor sensor 1 having a size of 253.6 mm arid a thickness of 0.1 mm is obtained.
(67) As described above, since the metal nitride material for a thermistor or the present embodiment consists of a metal nitride represented by the general formula: (M.sub.1-vA.sub.v).sub.xAl.sub.y(N.sub.1-wO.sub.w).sub.z ( where M represents at least one of Ti, V, Cr, Mn, Fe, and Co, A represents at least one of Sc, Zr, Mo, Nb, and W, 0.0<v<1.0, 0.70y/(x+y) 0.98, 0.45z0.55, 0<w0.35, and x+y+z=1), wherein the crystal structure thereof is a hexagonal wurtzite-type (space group: P6.sub.3mc (No. 186) single phase, a good B constant and an excellent heat resistance can be obtained without firing. In particular, the heat resistance can be further improved by the effect of oxygen (O) included in a crystal so as to compensate nitrogen defects in the crystal or the like.
(68) Since the metal nitride material for a thermistor is a columnar crystal extending in a vertical direction with respect to the surface of the film, the crystallinity of the film is high, so tear high heat resistance can be obtained.
(69) Furthermore, since the metal nitride material for a thermistor is more strongly oriented along the c-axis than the a-axis in a vertical direction with respect to the surface of the film, a high E constant as compared with the case of a strong a-axis orientation can be obtained.
(70) Since, in the method for producing the metal nitride material for a thermistor of the present embodiment, film deposition is performed by reactive sputtering in a nitrogen- and oxygen-containing atmosphere using an M-A-Al (where M represents at least one of Ti, V, Cr, Mn, Fe, and Co, arid A represents at least one of Sc, Zr, Mo, Nb, and W) alloy sputtering target, the metal nitride material for a thermistor, which consists of a metal nitride represented by the aforementioned general formula: (M, A).sub.xAl.sub.y(N, O).sub.z, can be deposited on a film without firing.
(71) Thus, since, in the film type thermistor sensor 1 using the metal nitride material for a thermistor of the present embodiment, the thin film thermistor portion 3 made of the metal nitride material for a thermistor is formed on the insulating film 2, the insulating film 2 having low heat resistance, such as a resin film, can be used because the thin film thermistor portion 3 is formed without firing and has a high B constant are; high heat resistance, so that a thin and flexible thermistor sensor having an excellent thermistor characteristic can be obtained.
(72) A substrate material using a ceramic such as alumina that has often been conventionally used has a problem that if the substrate material is thinned to a thickness of 0.1 mm, for example, the substrate material is very fragile and breaks easily. On the order hand, since a film can be used in the present embodiment, a very thin film, type thermistor sensor having a thickness of 0.1 mm, for example, can be provided.
EXAMPLES
(73) Next, the evaluation results of the materials according to Examples produced based on the above embodiment regarding the metal nitride material for a thermistor, a method for producing the same, and a film type thermistor sensor according to the present invention will be specifically described with reference to
(74) <Production of Film Evaluation Element>
(75) The film evaluation elements 121 shown in
(76) Firstly, each of the thin film thermistor portions 3 hawing a thickness of 500 nm, which were made of the metal nitride materials for a thermistor with the various composition ratios shown in Tables 2 to 7, was formed on an Si wafer with a thermal oxidation film as an Si substrate S by using a TiScAl alloy target, a TiZrAl alloy target, a TiMoAl alloy target, a TiNbAl alloy target, a TidAl alloy target, a CrZrAl alloy target, a CrNbAl alloy target, a CrMoAl alloy target, or a CrWAl alloy target with various composition ratios by the reactive sputtering method. The thin film thermistor portions 3 were formed under the sputtering conditions of an ultimate degree of vacuum of 510.sup.6 Pa, a sputtering gas pressure of from 0.1 to 1 Pa, a target input power (output) of from 100 to 500 W, and a nitrogen gas partial pressure and an oxygen gas partial pressure under a mixed gas (Ar gas+nitrogen gas+oxygen gas) atmosphere of from 10 to 100% and from 0 to 3%, respectively.
(77) Next, a Cr film having a thickness of 20 nm was formed and an Au film having a thickness of 200 nm was further formed on each of the thin film thermistor portions 3 by the sputtering method. Furthermore, a resist solution was coated on the stacked metal films using a spin coater, and then pre-baking was performed for 1.5 minutes at a temperature of 110 C. After being exposed by an exposure device, any unnecessary portion was removed by a developing solution, and then patterning was performed by post-baking for 5 minutes at a temperature of 150 C. Then, any unnecessary electrode portion was subject to wet etching using commercially available Au etchant and Cr etchant, and then the resist was stripped so as to form a pair of pattern electrodes 124, each having a desired comb shaped electrode portion 124a. Then, the resultant elements were diced into chip elements so as to obtain film evaluation elements 121 used for evaluating a B constant and for testing heat resistance.
(78) Note that the film evaluation elements 121 according to Comparative Examples, each having the composition ratio of (M, A).sub.xAl.sub.y(N, O).sub.z (where 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) outside the range of the present invention, and have different crystal systems, were similarly produced for comparative evaluation.
(79) <Film Evaluation>
(80) (1) Composition Analysis
(81) Elemental analysis was performed, on the thin film thermistor portions 3 obtained by the reactive sputtering method by X-ray photoelectron spectroscopy (XPS). In the XPS, a quantitative analysis was performed on a sputtering surface at a depth of 20 nm from the outermost surface by Ar sputtering. The results are sheen in Tables 2 to 7. In the following tables, the composition ratios are expressed by at %. Some of tine samples were also subject to a quantitative analysis for a sputtering surface at a depth of 100 nm from the outermost surface to confirm that it had the same composition within the quantitative accuracy as one in the sputtering surface at a depth of 20 nm.
(82) In the X-ray photoelectron spectroscopy (XPS), a quantitative analysis was performed under the conditions of an X-ray source of MgK (350 W), a path energy of 58.0 eV, a measurement interval of 0.125 eV, a photo-electron take-off angle with respect to a sample surface of 45 deg, and an analysis area of about 800 m. Note that the quantitative accuracy of N/(M+A+Al+N+O) and O/(M+A+Al+N+O) was 2%, arid that of Al/(M+A+Al) was 1, respectively (where 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).
(83) (2) Specific Resistance Measurement
(84) The specific resistance, of each of the thin film thermistor portions 3 obtained by the reactive spattering method was measured by the four-probe method at a temperature of 25 C. The results are shown in Tables 2 to 7.
(85) (3) Measurement of B Constant
(86) The resistance values for each of the film evaluation elements 121 at temperatures of 25 C. and 50 C. were measured in a constant, temperature bath, and a B constant was calculated based on the resistance values at temperatures of 25 C. and 50 C. The results are shown in Tables 2 to 7. In addition, it was confirmed that the film evaluation elements 121 were thermistors having a negative temperature characteristic by the resistance values at temperatures of 25 C. and 50 C.
(87) In the B constant calculating method of the present invention, a B constant is calculated by the following formula using the resistance values at temperatures of 25 C. and 50 C.
(88) B constant (K)=In(R25/R50)/(1/T25-1/T50)
(89) R25 (): resistance value at 25 C.
(90) R50 (): resistance value at 50 C.
(91) T25 (K): 298.15 K, which is an absolute temperature of 25 C. expressed in Kelvin
(92) T50 (K): 323.15 K, which is an absolute temperature of 50 C. expressed in Kelvin
(93) As can be seen from these results, a thermistor characteristic having a resistivity of 250 cm or higher and a B constant of 1500 K or higher is achieved in all of the Examples in which the composition ratios of (M, A).sub.xAl.sub.y(N, O).sub.z (where M represents at least, one of Ti, V, Cr, Mn, Fe, and Co, A represents at least one of Sc, Zr, Mo, Nb, and W) fall within the region enclosed by the points A, B, C, and D in the ternary phase diagrams shown in
(94) Graphs illustrating the relationships between a resistivity at 25 C. and a B constant from the above results are shown la
(95) From these graphs, the film evaluation elements 121, the composition ratios of which fall within the region where Al/(Ti+Sc+Al) is from 0.7 to 0.98 and N+O/(Ti+Sc+Al+N+O) is from 0.45 to 0.55 and each crystal system of which is a hexagonal wurtzite-type single phase, have a specific resistance value at a temperature of 25 C. of 250 cm or higher and a B constant of 1500 K or higher, which are the regions realizing a high resistance and a high B constant.
(96) The film evaluation elements 121, the composition ratios of which fall within the region where Al/(Ti+Zr+Al) is from 0.7 to 0.98 and N+O/(TiZrAl+N+O) is from 0.45 to 0.55 and each crystal system: of which is a hexagonal wurtzite-type single phase, also have a specific resistance value at a temperature of 25 C. of 250 cm or higher and a B constant of 1500 K or higher, which are the regions realizing a high resistance and a high B constant.
(97) The film evaluation elements 121, the composition ratios of which fall within the region where Al/(Ti+Mo+Al) is from 0.7 to 0.98 and N+O/(Ti+Mo+Al+N+O) is from 0.45 to 0.55 and each crystal system of which is a hexagonal wurtzite-type single phase, also have a specific resistance value at a temperature of 25 C. of 250 cm or higher and a B constant of 1500 K or higher, which are the regions realizing a high resistance and a high B constant.
(98) The film evaluation elements 121, the composition ratios of which fall within the region where Al/(Ti+Nb+Al) is from 0.7 to 0.98 and N+O/(ti+Nb+Al+N+O) is from 0.45 to 0.55 and each; crystal system of which is a hexagonal wurtzite-type single phase, also have a specific resistance value at a temperature of 25 C. of 250 cm or higher and a B constant of 1500 K or higher, which are the regions realizing a high resistance and a high B constant.
(99) Furthermore, the film evaluation elements 121 the composition ratios of which rail within the region where Al/(Ti+W+Al) is from 0.7 to 0.98 and N+O/(Ti+W+Al+N+O) is from 0.45 to 0.55 and each crystal system of which is a hexagonal wurtzite-type single phase also have a specific resistance value at a temperature of 25 C. of 250 cm or higher and a B constant of 1500 K or higher, which are the regions realizing a high resistance and a high B constant.
(100) In data shown in
(101) In the material according to Comparative Example 2, where M=Ti, A=Sc, as shown in Table 2, the composition ratio falls within the region where Al/(Ti+Sc+Al)<0.7, and the crystal system is a cubic NaCl-type phase. Thus, a material with the composition that falls within the region where Al/(Ti+Sc+Al)<0.7 has a specific resistance value at a temperature of 25 C. of less than 250 cm and a B constant of less than 1500 K, which are the regions of low resistance and low B constant.
(102) In the material according to Comparative Example 1 shown in Table 2, the composition ratio falls within the region where N+O/(Ti+Sc+Al+N+O) is less than 40%, that is, the material is in a crystal state where nitridation of metals contained therein is insufficient. Tee material according to Comparative Example 1 was neither a NaCl-type nor wurzite-type phase and had very poor crystallinity. In addition, it was found that the material according to this Comparative Example exhibited near-metallic behavior because both the B constant and the resistance value were very small.
(103) In the material according to Comparative Example 2, where M=Ti, A=Zr, as shown in Table 3, the composition ratio falls within the region where Al/(Ti+Zr+Al)<0.7, and the crystal system is a cubic NaCl-type phase. Thus, a material with the composition that falls within the region where Al/(Ti+Zr+Al)<0.7 has a specific resistance value at a temperature of 25 C. of less than 250 cm and a B constant of less than 1500 K, which are the regions of low resistance and low B constant.
(104) In the material according to Comparative Example 1 shown in Table 3, the composition ratio fails within the region where N+O/(ti+Zr+Al+N+) is less than 40%, that is, the material is in a crystal state where nitridation of metals contained therein is insufficient. The material according to comparative Example 1 was neither a NaCl-type nor wurtzite-type phase and had very poor crystallinity. In addition, it was found that the material according to this Comparative Example exhibited near-metallic behavior because both the B constant, and the resistance value were very small.
(105) In the material according to Comparative Example 2, where MTi, A=Mo, as shown in Table 4. the composition ratio falls within the region where Al/(Ti+Mo+Al<0.66, and the crystal system is a cubic NaCl-type phase. In the material according to Comparative Example 3 shown in Table 4, the composition ratio falls within the region where 0.66<Al/(Ti+Mo+Al)<0.70, and the crystal system is two coexisting phases of a NaCl-type phase and a wurtzite-type phase. Thus, a material with, the composition that falls within the region where Al/(Ti+Mo+Al)<0.7 has a specific resistance value at a temperature of 25 by of less than 250 cm and a B constant of less than 1500 K, which are the regions of low resistance and low B constant. In the material according to Comparative Example 1 shown in Table 4, the composition ratio falls within the region where N+O(Ti+Mo+Al+N+O) is less than 40%, that is, the material is in a crystal state where nitridation of metals contained therein is insufficient. The material according to Comparative Example 1 was neither a NaCl-type nor wurtzite-type phase and had very poor crystallinity. In addition, it was found that the material according to this Comparative Example exhibited near-metallic behavior because both the B constant and the resistance value were very small.
(106) In the material according to Comparative Example 2, where M=Ti, A=Nb, as shown in Table 5, the composition ratio falls within the region where Al/(Ti+Nb+Al)<0.7, and the crystal system is a cubic NaCl-type phase. Thus, a material with, the composition that falls within the region where Al/(Ti+Nb+Al)<0.7 has a specific resistance value at a temperature of 25 C. of less than 250 cm and a B constant of less than 1500 K, which are the regions of low resistance and low B constant.
(107) In the material according to Comparative Example 1 shown in Table 5, the composition ratio falls within the region, where N+O/(Ti+Nb+Al+N+O) is less than 40%, that is, the material is in a crystal state where nitridation of metals contained therein is insufficient. The material according to Comparative Example 1 was neither a NaCl-type nor wurtzite-type phase and had very poor crystallinity. In addition, it was found that the material according to this Comparative Example exhibited near-metallic behavior because both the B constant and the resistance value were very small.
(108) In the material according to Comparative Example 2, where M=Ti, A=W, as shown in Table 6, the composition ratio falls within the region where Al/(Ti+W+Al)<0.7, and the crystal system is a cubic NaCl-type phase. Thus, a material with the composition that falls within the region where Al/(Ti+W+Al)<0.7 has a specific resistance value at a temperature of 25 C. of less than 250 cm and a B constant of less than 1500 K, which are the regions of low resistance and low B constant.
(109) In the material according to Comparative Example 1 shown in Table 6, the composition ratio falls within the region where N+O/(Ti+W+Al+N+O) is less than 40%, and thus, the material is in a crystal state where nitridation of metals contained therein is insufficient. The material according to Comparative Example 1 was neither a NaCl-type nor wurtzite-type phase and had very poor crystallinity. In addition, it was found that the material according to this Comparative Example exhibited near-metallic behavior because both the B constant and the resistance value were very small.
(110) Note that, even in the materials according to the Examples shown in Table 7, where M is Cr and T is Zr, Nb, Mo, or W, when Al/(Cr A+Al) is from 0.7 to 0.98 and N+O/(Cr+A+Al+N+O) is from 0.45 to 0.55, a wurtzite-type hexagonal crystal having thermistor characteristic of high resistance and high B constant can be obtained.
(111) 4) Thin Film X-Ray Diffraction (Identification of Crystal Phase)
(112) The crystal phases of the thin film thermistor portions 3 obtained by the reactive sputtering method were identified by Grazing incidence X-ray Diffraction. The thin film X-ray diffraction is a small angle X-ray diffraction experiment. The measurement was performed under the conditions of a vessel of Cu, the angle of incidence of 1 degree, and 20 of from 20 to 130 degrees. Some of the samples were measured under the condition of the angle of incidence of 0 degree and 2 of from 20 to 100 degrees.
(113) As a result, of the measurement, a wurtzite-type phase (hexagonal, the same phase as that of AlN) was obtained in the region where Al/(M+A+Al)0.7 (where 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), whereas a NaCl-type phase (cubic, the same phase as that of TiN, ScN, ZrN, MoN, and NbN) was obtained in the region where Al/(M+A+Al)<0.66. It is also contemplated that a crystal phase in which a wurtzite-type phase and a NaCl-type phase coexist will be obtained in the region where 0.66<Al/(M+A+Al)<0.7.
(114) Thus, in the (M, A).sub.xAl.sub.y(N, O).sub.z-based material (where 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), the regions of high resistance and high B constant can be realized by the wurtzite-type phase having a ratio of Al/(M+A+Al)>0.7. In the Examples of the present invention; no impurity phase was confirmed and the crystal structure thereof was a wurtzite-type single phase.
(115) In Comparative Example 1 shown in Tables 2 to 6, the crystal phase thereof was neither a wurtzite-type nor NaCl-type phase as described above, and thus, could not be identified in the testing. In this Comparative Example, the peak width of XRD was very large, showing that the material had very poor crystallinity. It is contemplated that the crystal phase thereof was metal phase with insufficient nitridation and insufficient oxidation because it exhibited near-metallic behavior from the viewpoint of electric characteristics.
(116) TABLE-US-00002 TABLE 2 CRYSTAL AXIS EXHIBITING STRONG DEGREE OF ORIENTATION XRD PEAK IN VERTICAL INTENSITY DIRECTION RESULT OF RATIO OF WITH RESPECT ELECTRIC (100)/(002) TO SUBSTRATE SPUT- COMPOSITION RATIO PROPERTIES WHEN SURFACE WHEN TERING Ti/(Ti + Sc/(Ti + Al/(Ti + N/(Ti + O/(Ti + Al/ (N + O)/ SPECIFIC CRYSTAL CRYSTAL PHASE GAS Sc + Sc + Sc + Sc + Sc + (Ti + (Ti + Sc + N/ RESISTANCE PHASE IS IS WURTZITE PRES- Al + Al + Al + Al + Al + Sc + Sc/ Al + (Ti + Sc + O/ B CON- VALUE CRYSTAL WURTZITE TYPE (c-AXIS SURE N + O) N + O) N + O) N + O) N + O) Al) (Ti + Sc) N + O) Al + N) (N + O) STANT AT 25 C. SYSTEM TYPE OR a-AXIS) (Pa) (%) (%) (%) (%) (%) (%) (%) (%) (%) (%) (K) ( cm) COMPAR- UNKNOWN 14.4 0.2 51 30 5 78 1.3 35 31 14 61 5.E+00 ATIVE (INSUFFICIENT EXAMPLE 1 NITRIDATION) COMPAR- NaCl TYPE 17.9 0.2 32 44 6 64 1.1 50 47 13 345 5.E+01 ATIVE EXAMPLE 2 EXAMPLE 1 WURTZITE 0.05 c-AXIS <1.5 12.2 0.2 37 47 4 75 1.4 51 48 8 1887 1.E+04 TYPE EXAMPLE 2 WURTZITE 0.09 c-AXIS <1.5 9.0 0.1 38 47 6 81 0.9 53 50 11 2238 2.E+05 TYPE EXAMPLE 3 WURTZITE 0.83 c-AXIS <1.5 2.9 0.1 46 44 7 94 2.3 51 48 13 4220 6.E+07 TYPE EXAMPLE 4 WURTZITE 1.10 a-AXIS <1.5 4.0 0.3 48 40 8 92 6.3 48 43 17 3620 8.E+07 TYPE EXAMPLE 5 WURTZITE 1.32 a-AXIS <1.5 10.7 0.3 36 35 18 77 2.5 53 42 35 1782 2.E+04 TYPE EXAMPLE 6 WURTZITE 1.36 a-AXIS <1.5 9.1 0.2 42 45 4 82 2.3 49 47 9 2015 1.E+05 TYPE EXAMPLE 7 WURTZITE 2.36 a-AXIS <1.5 8.3 0.8 42 43 6 82 8.9 49 46 13 1893 3.E+05 TYPE
(117) TABLE-US-00003 TABLE 3 CRYSTAL AXIS EXHIBITING STRONG DEGREE OF ORIENTATION XRD PEAK IN VERTICAL INTENSITY DIRECTION RESULT OF RATIO OF WITH RESPECT ELECTRIC (100)/(002) TO SUBSTRATE SPUT- COMPOSITION RATIO PROPERTIES WHEN SURFACE WHEN TERING Ti/(Ti + Zr/(Ti + Al/(Ti + N/(Ti + O/(Ti + Al/ (N + O)/ SPECIFIC CRYSTAL CRYSTAL PHASE GAS Zr + Zr + Zr + Zr + Zr + (Ti + (Ti + Zr + N/ RESISTANCE PHASE IS IS WURTZITE PRES- Al + Al + Al + Al + Al + Zr + Zr/ Al + (Ti + Zr + O/ B CON- VALUE CRYSTAL WURTZITE TYPE (c-AXIS SURE N + O) N + O) N + O) N + O) N + O) Al) (Ti + Zr) N + O) Al + N) (N + O) STANT AT 25 C. SYSTEM TYPE OR a-AXIS) (Pa) (%) (%) (%) (%) (%) (%) (%) (%) (%) (%) (K) ( cm) COMPAR- UNKNOWN 14 4 49 24 9 74 21 33 26 28 188 8.E02 ATIVE (INSUFFICIENT EXAMPLE NITRIDATION) 1 COMPAR- NaCl TYPE 18 2 31 43 6 61 10 49 46 13 224 7.E+00 ATIVE EXAMPLE 2 EXAMPLE 1 WURTZITE 0.41 c-AXIS <1.5 9 2 36 43 10 76 17 53 48 19 2462 6.E+03 TYPE EXAMPLE 2 WURTZITE 0.66 c-AXIS <1.5 12 2 38 41 7 74 11 48 44 14 1625 3.E+04 TYPE EXAMPLE 3 WURTZITE 0.07 c-AXIS <1.5 6 1 42 46 5 85 16 51 48 11 2588 3.E+03 TYPE EXAMPLE 4 WURTZITE 0.05 c-AXIS <1.5 6 2 41 46 5 84 24 51 48 10 2771 9.E+03 TYPE EXAMPLE 5 WURTZITE 0.47 c-AXIS <1.5 3 1 48 43 5 93 26 48 46 10 5502 2.E+06 TYPE EXAMPLE 6 WURTZITE 2.05 a-AXIS <1.5 2 1 44 39 14 93 31 53 45 26 5245 2.E+06 TYPE
(118) TABLE-US-00004 TABLE 4 CRYSTAL AXIS EXHIBITING STRONG DEGREE OF ORIENTATION XRD PEAK IN VERTICAL INTENSITY DIRECTION RESULT OF RATIO OF WITH RESPECT ELECTRIC (100)/(002) TO SUBSTRATE SPUT- COMPOSITION RATIO PROPERTIES WHEN SURFACE WHEN TERING Ti/(Ti + Mo/(Ti + Al/(Ti + N/(Ti + O/(Ti + (N + O)/ SPECIFIC CRYSTAL CRYSTAL PHASE GAS Mo + Mo + Mo + Mo + Mo + Al/(Ti + (Ti + N/ RESISTANCE PHASE IS IS WURTZITE PRES- Al + Al + Al + Al + Al + Mo + Mo/ Mo +Al + (Ti + Mo + O/ B CON- VALUE CRYSTAL WURTZITE TYPE (c-AXIS SURE N + O) N + O) N + O) N + O) N + O) Al) (Ti +Mo) N + O) Al + N) (N + O) STANT AT 25 C. SYSTEM TYPE OR a-AXIS) (Pa) (%) (%) (%) (%) (%) (%) (%) (%) (%) (%) (K) ( cm) COMPAR- UNKNOWN 16 4 57 16 7 74 21 22 23 2.E+01 ATIVE (INSUFFICIENT EXAMPLE 1 NITRIDATION) COMPAR- NaCl TYPE 17 2 30 42 9 61 8 51 250 1.E+02 ATIVE EXAMPLE 2 COMPAR- NaCl TYPE + 9 8 38 34 11 69 47 45 1288 2.E+02 ATIVE WURTZITE EXAMPLE 3 TYPE EXAMPLE 1 WURTZITE 0.72 c-AXIS <1.5 5 6 41 43 5 78 56 48 45 10 2570 2.E+03 TYPE EXAMPLE 2 WURTZITE 0.10 c-AXIS <1.5 3 0.5 49 45 2 93 15 47 46 4 4550 1.E+07 TYPE EXAMPLE 3 WURTZITE 0.72 c-AXIS <1.5 7 5 43 40 5 80 41 45 42 12 2608 5.E+04 TYPE EXAMPLE 4 WURTZITE 1.10 a-AXIS <1.5 3 0.3 46 36 15 93 9 50 42 29 3868 2.E+06 TYPE EXAMPLE 5 WURTZITE 4.94 a-AXIS <1.5 8 5 37 37 13 74 41 50 42 26 2446 3.E+03 TYPE
(119) TABLE-US-00005 TABLE 5 CRYSTAL AXIS EXHIBITING STRONG DEGREE OF ORIENTATION XRD PEAK IN VERTICAL INTENSITY DIRECTION RESULT OF RATIO OF WITH RESPECT ELECTRIC (100)/(002) TO SUBSTRATE SPUT- COMPOSITION RATIO PROPERTIES WHEN SURFACE WHEN TERING Ti/(Ti + Mo/(Ti + Al/(Ti + N/(Ti + O/(Ti + (N + O)/ SPECIFIC CRYSTAL CRYSTAL PHASE GAS Mo + Mo + Mo + Mo + Mo + Al/(Ti + (Ti +Mo + N/ RESISTANCE PHASE IS IS WURTZITE PRES- Al + Al + Al + Al + Al + Mo + Mo/ Al + (Ti + Mo + O/ B CON- VALUE CRYSTAL WURTZITE TYPE (c-AXIS SURE N + O) N + O) N + O) N + O) N + O) Al) (Ti +Mo) N + O) Al + N) (N + O) STANT AT 25 C. SYSTEM TYPE OR a-AXIS) (Pa) (%) (%) (%) (%) (%) (%) (%) (%) (%) (%) (K) ( cm) COMPAR- UNKNOWN 17 3 56 22 2 74 15 23 22 8 34 6.E02 ATIVE (INSUFFICIENT EXAMPLE 1 NITRIDATION) COMPAR- NaCl TYPE 17 2 30 42 9 61 11 51 46 18 381 6.E01 ATIVE EXAMPLE 3 EXAMPLE 1 WURTZITE 0.03 c-AXIS <1.5 6 2 42 48 2 83 27 50 49 4 2549 6.E+02 TYPE EXAMPLE 2 WURTZITE 0.02 c-AXIS <1.5 5 2 42 46 5 85 26 50 48 8 2873 1.E+04 TYPE EXAMPLE 3 WURTZITE 0.10 c-AXIS <1.5 2 1 48 44 5 93 33 48 46 10 4252 1.E+06 TYPE EXAMPLE 4 WURTZITE 0.30 c-AXIS <1.5 10 1 36 44 9 76 12 52 48 16 2298 5.E+04 TYPE EXAMPLE 5 WURTZITE 0.87 c-AXIS <1.5 12 2 39 42 5 75 11 47 45 10 1812 3.E+02 TYPE EXAMPLE 6 WURTZITE 2.78 a-AXIS <1.5 6 2 41 37 14 84 28 51 43 27 2384 6.E+03 TYPE EXAMPLE 7 WURTZITE 2.56 a-AXIS <1.5 2 2 45 38 13 92 43 51 44 26 3523 3.E+05 TYPE
(120) TABLE-US-00006 TABLE 6 CRYSTAL AXIS EXHIBITING STRONG DEGREE OF ORIENTATION XRD PEAK IN VERTICAL INTENSITY DIRECTION RESULT OF RATIO OF WITH RESPECT ELECTRIC (100)/(002) TO SUBSTRATE SPUT- COMPOSITION RATIO PROPERTIES WHEN SURFACE WHEN TERING Ti/(Ti + W/(Ti + (N + O)/ SPECIFIC CRYSTAL CRYSTAL PHASE GAS W + W + Al/(Ti + N/(Ti + O/(Ti + (Ti + W + N/ RESISTANCE PHASE IS IS WURTZITE PRES- Al + Al + W + Al + W + Al + W + Al + Al/(Ti + W/(Ti + Al + (Ti + W + O/ B CON- VALUE CRYSTAL WURTZITE TYPE (c-AXIS SURE N + O) N + O) N + O) N + O) N + O) W + Al) W) N + O) Al + N) (N + O) STANT AT 25 C. SYSTEM TYPE OR a-AXIS) (Pa) (%) (%) (%) (%) (%) (%) (%) (%) (%) (%) (K) ( cm) COMPAR- UNKNOWN 4 1 76 14 5 94 10 19 15 25 53 8.E01 ATIVE (INSUFFICIENT EXAMPLE 1 NITRIDATION) COMPAR- NaCl TYPE 17 3 32 43 5 61 15 48 45 10 469 3.E+00 ATIVE EXAMPLE 3 EXAMPLE 1 WURTZITE 0.01 c-AXIS <1.5 6 6 39 46 3 76 53 49 47 6 2454 2.E+03 TYPE EXAMPLE 2 WURTZITE 0.01 c-AXIS <1.5 6 8 39 43 4 73 55 47 45 8 2300 1.E+03 TYPE EXAMPLE 3 WURTZITE 0.48 c-AXIS <1.5 3 1 49 44 3 92 14 47 46 6 3350 2.E+06 TYPE EXAMPLE 4 WURTZITE 1.41 a-AXIS <1.5 3 0.4 46 39 12 93 12 50 44 23 2950 3.E+05 TYPE EXAMPLE 5 WURTZITE 1.35 a-AXIS <1.5 5 7 38 42 8 76 54 50 46 17 1810 6.E+02 TYPE
(121) TABLE-US-00007 TABLE 7 CRYSTAL AXIS EXHIBITING STRONG DEGREE OF ORIENTATION XRD PEAK IN VERTICAL INTENSITY DIRECTION RATIO OF WITH RESPECT COMPOSITION RATIO (100)/(002) TO SUBSTRATE SPUT- M/ A/ Al/ N/ WHEN SURFACE WHEN TERING (M + (M + (M + (M + CRYSTAL CRYSTAL PHASE GAS A + A + A + A + PHASE IS IS WURTZITE PRES- Al + Al + Al + Al + CRYSTAL WURTZITE TYPE (c-AXIS SURE M A N + O) N + O) N + O) N + O) SYSTEM TYPE OR a-AXIS) (Pa) ELEMENT ELEMENT (%) (%) (%) (%) EXAMPLE 1 WURTZITE 0.04 c-AXIS <1.5 Cr Zr 3 4 42 40 TYPE EXAMPLE 2 WURTZITE <0.01 c-AXIS <1.5 Cr Nb 0.4 4 46 44 TYPE EXAMPLE 3 WURTZITE <0.01 c-AXIS <1.5 Cr Nb 0.2 4 46 45 TYPE EXAMPLE 4 WURTZITE 0.07 c-AXIS <1.5 Cr Mo 3 5 42 38 TYPE EXAMPLE 5 WURTZITE 0.07 c-AXIS <1.5 Cr W 4 5 42 37 TYPE RESULT OF ELECTRIC PROPERTIES COMPOSITION RATIO SPECIFIC O/ (N + O)/ RESIS- (M + Al/ (M + TANCE A + (M + A/ A + N/ VALUE Al + A + (M + Al + (M + A + O/ B CON- AT N + O) Al) A) N + O) Al + N) (N + O) STANT 25 C. (%) (%) (%) (%) (%) (%) (K) ( cm) EXAMPLE 1 11 86 57 51 45 22 2211 2.E+04 EXAMPLE 2 6 92 90 50 47 13 2479 6.E+04 EXAMPLE 3 5 92 94 50 48 10 2588 7.E+04 EXAMPLE 4 12 82 61 49 43 24 1802 4.E+02 EXAMPLE 5 12 82 56 49 42 25 1646 4.E+02
(122) Next, since all the materials according to the Examples of the present invention were wurtzite-type phase films having strong orientation, whether the films have a strong a-axis orientation or c-axis orientation of the crystal axis in a vertical direction (film thickness direction) with respect to the Si substrate S was examined by XRD. At this time, in order to examine the orientation of the crystal axis, the peak intensity ratio of (100)/(002) was measured, where (100) is the hkl index indicating a-axis orientation and (002) is the hkl index indicating c-axis orientation.
(123) Note that it was confirmed that a wurtzite-type single phase was formed in the same manner even when the thin film thermistor portion 3 was deposited on a polyimide film under the same deposition condition. It was also confirmed that the crystal orientation did not change even when the thin film thermistor portion 3 was deposited, on a polyimide film under the same deposition condition.
(124) Exemplary XRD profiles of the materials according to the Examples exhibiting strong c-axis orientation are shown in
(125) In the Example shown in
(126) In the Example shown in
(127) In the example shown, in
(128) In the Example shown in
(129) As can be seen from she results in these Examples, the intensity of (002) was much stronger than that of (100).
(130) The asterisk (*) in the graphs shows the peak originating from the device or the Si substrate with a thermal oxidation film, and thus, it was confirmed that the peak with the asterisk (*) in the graphs was neither the peak originating from, a sample itself nor the peak originating from an impurity phase. In addition, symmetrical measurement was performed at a 0 degree angle of incidence, confirming that the peak indicated by (*) is lost in the symmetrical measurement, and thus, that it was the peak originating from the device or the Si substrate with a thermal oxidation film.
(131) Next, the correlations between a crystal structure and its electric characteristic were compared with each. other in detail regarding the Examples of the present invention in which the wurtzite-type materials were employed.
(132) As shown in Tables 2 to 6, the crystal axis of some materials is strongly oriented along a c-axis in a vertical direction with respect to the surface of the substrate and that of other materials is strongly oriented along an a-axis in a vertical direction with respect to the surface of the substrate among the materials hawing neatly the same Al/(T+A+Al) ratio, that is, Al/(Ti+Sc+Al) ratio, Al/(Ti+Zr+Al) ratio, Al/(Ti+Mo+Al) ratio, Al/(Ti+Nb+Al) ratio, or Al/(Ti+W+Al) ratio.
(133) When both groups were compared to each other, it was found that the materials having a strong c-axis orientation had a higher B constant than that of the materials having a strong a-axis orientation provided that they have nearly the same Al/(Ti+A+Al) ratio.
(134) In addition, the crystal axis of some materials is strongly oriented along a c-axis in a vertical direction with respect to the surface of the substrate and that of other materials is strongly oriented along an a-axis in a vertical direction with respect to the surface of the substrate among the materials having nearly the same Zr/(Ti+Sc), Zr/(Ti+Zr), Mo/(Ti+Mo), Nb/(Ti+Nb), or W/(Ti+W) ratio. Also in this case, it was found that the materials having a strong c-axis orientation had a higher B constant than that of the materials having a strong a-axis orientation provided that they have nearly the same Zr/(Ti+Sc) ratio, Zr/(Ti+Zr) ratio, Mo/(Ti+Mo) ratio, Nb/(Ti+Nb) ratio, or W/(Ti+W) ratio.
(135) When focus was placed on the amount of N (i.e., N/(Ti+A+Al+N+O), it was found that the materials having a strong c-axis orientation had a slightly larger amount of nitrogen than that of the materials having a strong a-axis orientation. Furthermore, when focus was placed on the amount of O (i.e., O/(N+O)), it was found that the materials hawing a strong a-axis orientation had a slightly larger amount of oxygen than, that of the materials having a strong c-axis orientation.
(136) <Crystal Form Evaluation>
(137) Next, as an exemplary crystal form in the cross-section of the than film thermistor portion 3, a cross-sectional SEM photograph of the thin film thermistor portion 3 according to the Example in the case where M=Ti, A=Sc (where Al/(Ti+Sc+Al)=0.81, wurtzite-type hexagonal, and strong c-axis orientation, in which the thin film thermistor portion 3 having a thickness of about 430 nm was deposited on the Si substrate S with a thermal oxidation film, is shown in
(138) A cross-sectional SEP photograph of the thin film thermistor portion 3 according to the Example in the case where M=Ti, A=Zr (where Al/(Ti+Zr+Al)=0.84, wurtzite-type hexagonal, and strong c-axis orientation) in which the thin film thermistor portion 3 having a thickness of about 350 nm was deposited on the Si substrate S with a thermal oxidation film, is also shown in
(139) A cross-sectional SEM photograph of the thin film thermistor portion 3 according to the Example in the case where M=Ti, A=Mo (where Al/(Ti+Mo+)=0.93, wurtzite-type hexagonal, and strong c-axis orientation), in which the thin film thermistor portion 3 having a thickness of about 300 nm was deposited on the Si substrate S with a thermal oxidation film, is also shown in
(140) A cross-sectional SEM photograph of the thin film thermistor portion 3 according to the Example in the case where M=Ti, A=Nb (where Al/(Ti+Nb+Al)=0.83, wurtzite-type hexagonal, and strong c-axis orientation, in which the thin, film thermistor portion 3 having a thickness of about 300 nm was deposited on the Si substrate S with a thermal oxidation film, is also shown in
(141) Furthermore, a cross-sectional SEM photograph of the thin film thermistor portion 3 according to the Example in the case where M=Ti, A=W (where Al/(Ti+W+Al)=0.76, wurtzite-type hexagonal, and strong c-axis orientation), in which the thin film thermistor portion 3 having a thickness of about 450 nm was deposited on the Si substrate S with a thermal oxidation film, is also shown in
(142) The samples in these Examples were obtained by breaking the Si substrates 5 by cleavage. The photographs were taken by tilt observation at an angle of 45 degrees.
(143) As can be seen from these photographs, the samples were formed of a high-density columnar crystal in all Examples. Specifically, the growth of columnar crystals in a vertical direction with respect to the surface of the substrate was observed both in the Examples revealing a strong c-axis orientation and in the Examples revealing a strong a-axis orientation. Note that, the break of the columnar crystal, was generated upon breaking the Si substrate 5 by cleavage.
(144) Regarding the site of a columnar crystal in the drawings, in the Example revealing a strong c-axis orientation shown in
(145) In the Example revealing a strong c-axis orientation shown in
(146) In the Example revealing a strong c-axis orientation shown in
(147) In the Example revealing a strong c-axis orientation shown in
(148) In the Example revealing a strong c-axis orientation shown in
(149) Note that the grain size here is the diameter of a columnar crystal along the surface of a substrate and the length is that of a columnar crystal in a vertical direction with respect to the surface of the substrate (film thickness).
(150) When the suspect ratio of a columnar crystal is defined as length/grain size, the materials according to the present Examples have an aspect ratio of 10 or higher. It is contemplated that a film has a nigh-density due to the small grain size of a columnar crystal. It was also confirmed that when a film having a thickness of 200 nm. 500 nm, or 1000 nm was deposited on a Si substrate S with a thermal oxidation film, a columnar crystal having a high-density density was formed as described above.
(151) <Heat Resistance Test Evaluation
(152) In some of the materials according to the Examples and the Comparative Examples shown in Tables 2 to 7, a resistance value and a B constant before and after the heat resist since test at a temperature of 125 C. for 1000 hours in air were evaluated. The results are shown in Tables 8 to 12. The material according to Comparative Example made of a conventional TaAlN-based material was also evaluated in the same manner for comparison. In addition, a neat resistance test was performed on the thin film thermistor portion 3 made of the (M+A)-AlN-based material (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 according to Reference Example 1 (hexagonal wurtzite-type, strong c axis orientation) by reactive sputtering under a mixed gas (Ar gas+nitrogen gas; atmosphere containing no oxygen in the same manner for reference. The results are also shown in Tables 8 to 12.
(153) As can be seen from these results, although the Al concentration and the nitrogen concentration vary, both the rising rate of a resistance value and the rising rate of a B constant of the (M, A).sub.xAl.sub.y(N, O).sub.z-based material (where 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) are smaller than those of the TaAlN-based material according to the Comparative Example, and the heat resistance of the (M, A).sub.zAl.sub.y(N, O).sub.z-based material (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) based on the electric characteristic change before and after the heat resistance test is more excellent than that of the TaAlN-based material according to the Comparative Example when the comparison is made by using the materials according to the Examples basing a level of B constant similar to that of the Comparative Example.
(154) In addition, it is found that although the heat resistance of the (M+A.)-Albased material according to Reference Example 1, which does not positively contain oxygen, is more excellent than that of the Comparative Example, the (M+A)-Al(N+O)-based material according to Example of the present invention, which positively contain oxygen, has lower rising rate of resistance valve and more excellent heat resistance compared with Reference Example 1.
(155) Note that, in the TaAl N-based material, the ionic radius of Ta is very large compared to that of Ti, Zr, Mo, Nb, and Al, and thus, a wurtzite-type phase cannot be produced in the high-concentration Al region. It is contemplated that the (M+A)-AlN or (M+A)-Al(N+O)-based material having a wurtzite-type phase has better heat resistance than the TaAlN-based material because the TaAlN-based material is not a wurtzite-type phase.
(156) TABLE-US-00008 TABLE 8 RISING RATE RISING RATE OF SPECIFIC OF B RESISTANCE CONSTANT AT 25 C. AFTER AFTER HEAT SPECIFIC HEAT RESIS- RESISTANCE RESISTANCE TANCE TEST TEST AT Al/ VALUE AT 125 C. 125 C. M + A M + A Al N O (M + Al) B25-50 AT 25 C. FOR 1,000 FOR 1,000 ELEMENT (%) (%) (%) (%) (%) (K) ( cm) HOURS (%) HOURS (%) COMPARATIVE TA 59 2 35 5 3 2688 6.E+02 12 6 EXAMPLE EXAMPLE 2 Ti, Sc 9.1 38 47 6 81 2238 2.E+05 <1 <1 EXAMPLE 6 Ti, Sc 9.3 42 45 4 82 2015 1.E+05 <2 <1 REFERENCE Ti, Sc 9.5 43 47 82 2231 1.E+05 <4 <1 EXAMPLE 1
(157) TABLE-US-00009 TABLE 9 RISING RATE RISING RATE OF SPECIFIC OF B RESISTANCE CONSTANT AT 25 C. AFTER AFTER HEAT SPECIFIC HEAT RESIS- RESISTANCE RESISTANCE TANCE TEST TEST AT Al/ VALUE AT 125 C. 125 C. M + A M + A Al N O (M + Al) B25-50 AT 25 C. FOR 1,000 FOR 1,000 ELEMENT (%) (%) (%) (%) (%) (K) ( cm) HOURS (%) HOURS (%) COMPARATIVE Ta 59 2 35 5 3 2888 6.E+02 12 6 EXAMPLE EXAMPLE 4 Ti, Zr 8 41 46 5 84 2771 9.E+03 <2 <1 REFERENCE Ti, Zr 8 44 48 84 2764 7.E+03 <4 <1 EXAMPLE 1
(158) TABLE-US-00010 TABLE 10 RISING RATE RISING RATE OF SPECIFIC OF B RESISTANCE CONSTANT AT 25 C. AFTER AFTER HEAT SPECIFIC HEAT RESIS- RESISTANCE RESISTANCE TANCE TEST TEST AT Al/ VALUE AT 125 C. 125 C. M + A M + A Al N O (M + Al) B25-50 AT 25 C. FOR 1,000 FOR 1,000 ELEMENT (%) (%) (%) (%) (%) (K) ( cm) HOURS (%) HOURS (%) COMPARATIVE Ta 59 2 35 5 3 2688 6.E+02 12 6 EXAMPLE EXAMPLE 1 Ti, Mo 11 41 43 5 78 2576 2.E+03 <2 <1 REFERENCE Ti, Mo 12 42 46 78 2503 2.E+03 <4 <1 EXAMPLE 1
(159) TABLE-US-00011 TABLE 11 RISING RATE RISING RATE OF SPECIFIC OF B RESISTANCE CONSTANT AT 25 C. AFTER AFTER HEAT SPECIFIC HEAT RESIS- RESISTANCE RESISTANCE TANCE TEST TEST AT Al/ VALUE AT 125 C. 125 C. M + A M + A Al N O (M + Al) B25-50 AT 25 C. FOR 1,000 FOR 1,000 ELEMENT (%) (%) (%) (%) (%) (K) ( cm) HOURS (%) HOURS (%) COMPARATIVE Ta 59 2 35 5 3 2688 6.E+02 12 6 EXAMPLE EXAMPLE 1 Ti, Nb 8 42 48 2 83 2549 6.E+02 <2 <1 REFERENCE Ti, Nb 192 42 49 82 2447 6.E+02 <4 <1 EXAMPLE 1
(160) TABLE-US-00012 TABLE 12 RISING RATE RISING RATE OF SPECIFIC OF B RESISTANCE CONSTANT AT 25 C. AFTER AFTER HEAT SPECIFIC HEAT RESIS- RESISTANCE RESISTANCE TANCE TEST TEST AT Al/ VALUE AT 125 C. 125 C. M + A M + A Al N O (M + Al) B25-50 AT 25 C. FOR 1,000 FOR 1,000 ELEMENT (%) (%) (%) (%) (%) (K) ( cm) HOURS (%) HOURS (%) COMPARATIVE Ta 59 2 35 5 3 2688 6.E+02 12 6 EXAMPLE EXAMPLE 1 Ti, W 12 39 46 3 76 2454 2.E+03 <4 <2 REFERENCE Ti, W 13 40 47 76 2350 1.E+03 <5 <2 EXAMPLE 1
(161) The technical scope of the present invention is not limited to the aforementioned embodiments and Examples, but the present invention may be modified in various ways without departing from the scope or teaching of the present invention.
(162) Although in the above Examples, the metal nitride material for a thermistor which consist of a metal nitride of (M, A) Al (N,O) (where A represents at least one of Sc, Zr, Mo, Nb, and W) was produced in the case where M is Ti or Cr as an example, at least one of V, Mn, Fe, and Co can be substituted for at least part of Ti or Cr so as to obtain the same characteristic.
REFERENCE NUMERALS
(163) 1: film type thermistor sensor, 2: insulating film, 3: thin film thermistor portion, 4 and 124: pattern electrode