JP2019129188A - Thermistor and method for manufacturing the same, and thermistor sensor - Google Patents

Abstract

To provide an amorphous thermistor capable of being directly formed on a film or the like and having high resistance and a high B constant, a method for manufacturing the amorphous thermistor, and a thermistor sensor.SOLUTION: A thermistor is made of an amorphous metal nitride represented by a general formula: SiWN(0<y/(x+y)≤0.30, 0.45≤z/(x+y+z)≤0.50, x+y+z=1). A method for manufacturing the thermistor includes a film formation step of forming a film by performing reactive sputtering in a nitrogen-containing atmosphere using a sputtering target comprising a mixed sintered body of SiNand W.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a thermistor capable of direct film formation on a film or the like, a method of manufacturing the same, and a thermistor sensor.

  A thermistor material used for a temperature sensor or the like is required to have a high B constant for high accuracy and high sensitivity. In addition, in thin film thermistor materials, as a thin film thermistor material with high crystallinity, which is excellent in the degree of crystal orientation, in recent years, a metal nitride material which is not fired and does not require heat treatment, and can obtain a high B constant is developed. There is.

For example, the inventors of the present application have made extensive research and development on Al—N-based metal nitride materials for thermistors. As the metal nitride materials for thermistors that can be directly formed on an insulating substrate without firing, the general formula: Ti _x Al _y N _z (0.70 ≦ y / (x + y) ≦ 0.95, 0.4 ≦ z ≦ 0.5, x + y + z = 1), the crystal structure of which is hexagonal We are developing a metal nitride material for thermistors, which is a single-phase wurtzite type of W series (Patent Document 1). In addition, it can be formed by non-baking, is at least one nitride material of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Si and Al, and has the above crystal structure and is high Materials have been developed to obtain B constants (Patent Documents 2 to 7).

JP, 2013-179161, A JP, 2014-123646, A JP, 2014-236204, A JP, 2015-65408, A JP, 2015-65417, A JP, 2015-73077, A JP, 2015-73075, A

In addition to the metal nitride material described above, there is also a demand for a thermistor that can be directly deposited on an insulating film and that can obtain a high B constant without firing.
In particular, when the thermistor film made of a metal nitride material having high crystallinity is formed on an insulating film such as polyimide or formed under conditions where the compressive stress is large, cracks are easily generated. There is a need for an amorphous, high B constant thermistor.

  The present invention has been made in view of the above-mentioned problems, and provides an amorphous thermistor which hardly forms a crack even when formed on an insulating film and can obtain a high B constant, a method of manufacturing the same, and a thermistor sensor The purpose is to

The present invention adopts the following configuration in order to solve the problems. That is, the thermistor according to the first invention has a general formula: Si _x W _y N _z (0 <y / (x + y) ≦ 0.30, 0.45 ≦ z / (x + y + z) ≦ 0.50, x + y + z = 1. It consists of an amorphous metal nitride shown by these.

In this thermistor, an amorphous material represented by a general formula: Si _x W _y N _z (0 <y / (x + y) ≦ 0.30, 0.45 ≦ z / (x + y + z) ≦ 0.50, x + y + z = 1) Since the metal nitride of the above, it is hard to generate a crack and has a thermistor characteristic with a high B constant.
Note that if “z / (x + y + z)” (that is, N / (Si + W + N) composition ratio) is less than 0.45, SiW becomes insufficiently nitrided, so that the specific resistance becomes too small and the metal behaves. And the thermistor characteristics cannot be obtained.
Moreover, since insulation will become too high when said "z / (x + y + z)" exceeds 0.50, the use as a thermistor is difficult.
In addition, if the above “y / (x + y)” (ie, W / (Si + W) composition ratio) is zero, that is, if it is SiN amorphous, the insulation becomes too high, making it difficult to use as a thermistor. It is.
Furthermore, when the above “y / (x + y)” exceeds 0.3, sufficient heat resistance can not be obtained, and thus the rate of change in resistance after use at high temperatures becomes large.

A thermistor sensor according to a second invention is a pair of base material, a thin film thermistor portion formed by the thermistor of the first invention on the base material, and a pair formed at least above and below the thin film thermistor portion. The counter electrode is provided.
That is, in this thermistor sensor, since the thin film thermistor portion is formed by the thermistor of the first invention, cracks are hardly generated in the thin film thermistor portion, and a high B constant can be obtained, so a thermistor having good thermistor characteristics. A sensor is obtained.

A thermistor sensor according to a third invention is characterized in that, in the thermistor sensor of the second invention, the base material is an insulating film.
That is, in this thermistor sensor, even if a large compressive stress is applied to the thin film thermistor portion formed on the insulating film such as polyimide, the occurrence of the crack is suppressed, and good thermistor characteristics can be obtained. In addition, since the substrate is a flexible insulating film, a flexible thermistor sensor having flexibility as a whole can be obtained.

A method of manufacturing a thermistor according to a fourth aspect of the present invention is a method of manufacturing the thermistor of the first aspect, wherein a sputtering target formed of a mixed sintered body of Si ₃ N ₄ and W is used in a nitrogen-containing atmosphere. It has the film-forming process which forms into a film by performing reactive sputtering.
That is, the method of manufacturing the thermistor includes a film forming step of forming a film by performing reactive sputtering in a nitrogen-containing atmosphere using a sputtering target formed of a mixed sintered body of Si ₃ N ₄ and W. Since the target contains Si ₃ N ₄ nitride, it is possible to achieve good nitriding of the film, and adjust the nitrogen content during sputtering to obtain the amount of nitriding of the Si _x W _y N _z film (N / (Si + W + N) composition ratio can be adjusted, and a thermistor of amorphous Si _x W _y N _z can be stably produced.

The present invention has the following effects.
That is, according to the thermistor according to the present invention, the general formula: Si _x W _y N _z (0 <y / (x + y) ≦ 0.30, 0.45 ≦ z / (x + y + z) ≦ 0.50, x + y + z = 1 Since it is made of an amorphous metal nitride as shown in 1.), it is resistant to cracking and has a thermistor characteristic with a high B constant.
In addition, according to the method of manufacturing a thermistor according to the present invention, a film forming step of performing reactive sputtering to form a film in a nitrogen-containing atmosphere using a sputtering target formed of a mixed sintered body of Si ₃ N ₄ and W Therefore, the amount of nitriding of the Si _x W _y N _z film can be adjusted by adjusting the nitrogen content during sputtering, and a stable thermistor of amorphous Si _x W _y N _z can be produced. can do.
Further, according to the thermistor sensor of the present invention, since the thin film thermistor portion is formed by the thermistor of the present invention, cracks are hardly generated, and a high B constant is obtained, so that the thermistor sensor has good thermistor characteristics. A thermistor sensor is obtained.

FIG. 5 is a cross-sectional view showing a thermistor on a substrate in an embodiment of a thermistor, a method of manufacturing the same, and a thermistor sensor according to the present invention. In the embodiment according to the present embodiment and the present invention, it is a front view and a plan view showing a thermistor sensor and an element for film evaluation. It is a graph which shows the result of having conducted elemental analysis by X-ray photoelectron spectroscopy (XPS) about Example 1 which concerns on this invention. In the Example and comparative example which concern on this invention, it is a graph which shows B constant with respect to 25 degreeC specific resistance value. In the Example which concerns on this invention, it is a graph which shows B constant with respect to composition ratio N / (Si + W + N). It is a graph which shows the result of X-ray diffraction (XRD) about Example 1 which concerns on this invention.

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

Thermistor of this embodiment, the general _formula: represented by _{Si x W y N z (0} <y / (x + y) ≦ 0.30,0.45 ≦ z / (x + y + z) ≦ 0.50, x + y + z = 1) It is a thermistor material made of amorphous metal nitride.
In addition, judgment of the amorphous was implemented by X-ray-diffraction experiment. Since a resin substrate such as polyimide has a large absorption of X-rays and it is difficult to determine whether it is amorphous, a Si _x W _y N _z film is formed on a Si substrate with a thermal oxidation (SiO ₂ ) film, and crystal I judged the sex. Specifically, it was carried out by grazing incidence X-ray diffraction, and the tube was made Cu, and the incident angle was made 1 degree. Moreover, the incident angle was made into 0 degree and symmetrical measurement (general (theta) 2-(theta) measurement) was implemented in 2 (theta) = 20-100 degree. At this time, the absence of crystallinity peaks such as the a-axis orientation (100) and the c-axis orientation (002) is judged to be amorphous.

Further, the thermistor of the present embodiment may contain oxygen within a range where the thermistor characteristics are not significantly changed. When the thermistor of this embodiment is formed into a film by sputtering described later, oxygen (composition ratio O / (Si + W + N + O)) contained as an unavoidable impurity in the film is less than 2% in all cases.
In addition, even when the surface of the thermistor of this embodiment is oxidized, an oxide layer may be present on the surface as long as the thickness of the oxide layer is a film thickness (for example, several nm or less) with little electrical influence.

  Further, as shown in FIGS. 1 and 2, the thermistor sensor 10 according to the present embodiment includes the substrate 2, the thin film thermistor unit 1 formed of the thermistor on the substrate 2, the thin film thermistor unit 1 and And a pair of counter electrodes 5 formed on at least one of the lower sides.

As the substrate 2, an insulating film such as polyimide is employed.
In addition, although the said insulating film can also be produced also by PET: polyethylene terephthalate, PEN: polyethylene naphthalate etc., a softness | flexibility and heat resistance are requested | required. For example, since the maximum use temperature is as high as about 200 ° C. for measuring the temperature of the fixing roller, a polyimide film excellent in heat resistance is desirable.
For example, the pair of counter electrodes 5 is formed by patterning a laminated metal film of a Cr film and an Au film, is opposed to each other on the thin film thermistor portion 1, and has a comb pattern having a plurality of comb portions 5a. ing.

  The manufacturing method of the said thermistor and the manufacturing method of the thermistor sensor using the same are demonstrated below.

The method of manufacturing the thermistor of this embodiment includes a film forming step of performing film formation by performing reactive sputtering in a nitrogen-containing atmosphere using a sputtering target made of a mixed sintered body of Si ₃ N ₄ and W. ing.
For example, in order to form an amorphous Si-W-N film, a sputtering target consisting of a mixed sintered body of Si ₃ N ₄ and W is used, and the sputtering condition is an ultimate vacuum degree of 4 × 10 ⁻⁵ Pa, The nitrogen gas fraction is set to, for example, 40% in a mixed gas atmosphere of Ar gas + nitrogen gas with a sputtering gas pressure of 0.67 Pa and a target input power (output) of 200 W.
In addition, when a Si-W alloy sputtering target is used, it is preferable that the sputtering target contains a nitride such as Si ₃ N ₄ because it is difficult to nitride the film. In the present embodiment, a sputtering target material containing Si ₃ N ₄ is used, but in order to obtain a better nitride film, a material containing W—N may be used. Good.

Moreover, when manufacturing the thermistor sensor 10 of this embodiment, the thin film thermistor part 1 is formed into a film by the film-forming process of the manufacturing method of the said thermistor first on the base material 2. FIG.
Next, by sputtering, for example, a Cr film is formed to 20 nm, and an Au film is further formed to 200 nm. Furthermore, after applying a resist solution with a bar coater, prebaking is performed at 110 ° C. for 1 minute and 30 seconds, after exposure with an exposure device, unnecessary portions are removed with a developer, and post baking at 150 ° C. for 5 minutes Perform patterning at Thereafter, the unnecessary electrode portion is wet-etched with a commercially available Au etchant and Cr etchant to form a counter electrode 5 having a desired comb portion 5a by resist peeling as shown in FIG. Thus, the thermistor sensor 10 of the present embodiment is manufactured.

Thus, in the thermistor of this embodiment, the general formula: Si _x W _y N _z (0 <y / (x + y) ≦ 0.30, 0.45 ≦ z / (x + y + z) ≦ 0.50, x + y + z = 1) Since it consists of an amorphous metal nitride shown by these, it is hard to generate a crack and has the thermistor characteristic with high B constant.

  Further, in the thermistor sensor 10 of the present embodiment, since the thin film thermistor portion 1 is formed of the above-mentioned thermistor, the thin film thermistor portion 1 is unlikely to be cracked, a high B constant is obtained, and the thermistor characteristics are good. A thermistor sensor is obtained. In particular, even if a large compressive stress is applied to the thin film thermistor portion 1 formed on an insulating film such as polyimide, the occurrence of cracks is suppressed and good thermistor characteristics are obtained. When the substrate 2 is a flexible insulating film, a flexible thermistor sensor having flexibility as a whole can be obtained.

Furthermore, in the method of manufacturing a thermistor according to the present embodiment, there is a film forming step of forming a film by performing reactive sputtering in a nitrogen-containing atmosphere using a sputtering target made of a mixed sintered body of Si ₃ N ₄ and W. As a result, Si ₃ N ₄ in the target enables good nitridation of the film, and adjustment of the nitrogen content in sputtering enables adjustment of the nitridation amount of the Si _x W _y N _z film. A stable thermistor of amorphous Si _x W _y N _z can be produced.

  Next, the results of evaluation of the thermistor, the method of manufacturing the same, and the thermistor sensor according to the present invention by examples manufactured based on the above embodiment will be specifically described with reference to FIGS. 3 to 6.

<Production of element for film evaluation>
As an example of the present invention and a comparative example, the thermistor sensor shown in FIG. 2 having a thermistor of an amorphous Si—W—N film using a substrate 22 of a Si substrate with a thermal oxide film (SiO ₂ ) is evaluated as a film. The device was prepared as follows.
First, using a sputtering target consisting of a mixed sintered body of Si ₃ N ₄ and W by reactive sputtering, amorphous Si-- is formed on the base material 22 of the Si substrate with a thermal oxide film (SiO ₂ ). A W-N thin film thermistor portion 1 was formed. A plurality of examples in which the thin film thermistor portion 1 was formed into a film were produced by changing the composition ratio (Examples 1 to 6). The sputtering conditions for amorphous Si—W—N at that time are the same as described above.

As a comparative example, an amorphous Si-N film (a reactive Si sputtering method using a sputtering target consisting only of Si ₃ N ₄ ) is applied on the base material 22 of the Si substrate with a thermal oxide film (SiO ₂ ). Comparative Examples 1 and 2 were formed on the portion corresponding to the thin film thermistor portion 1. In addition, an amorphous Si—W—N outside the composition range of the present invention is formed on the base material 22 of the Si substrate with a thermal oxide film (SiO ₂ ) by a reactive sputtering method using a Si—W alloy sputtering target. A film (Comparative Example 3) was formed on a portion corresponding to the thin film thermistor section 1.

  Next, the counter electrode 5 was formed on the thin film thermistor portion 1 under the above-described conditions. Then, this was diced into chips to obtain film evaluation elements of Examples and Comparative Examples of the present invention. The film thickness of the thin film thermistor portion 1 of amorphous Si-W-N in the example is 200 nm, and the film thickness of the amorphous Si-N film or the amorphous Si-W-N film in the comparative example is It is 200 nm.

<Evaluation of membrane>
(1) Composition Analysis Elemental analysis was performed on the thin film thermistor unit 1 by X-ray photoelectron spectroscopy (XPS). In this XPS, quantitative analysis was performed on a sputtered surface having a depth of 20 nm from the outermost surface by Ar sputtering. The results are shown in Table 1. The composition ratios in the following table are indicated by “atomic%”. For some samples, quantitative analysis is performed on the sputtered surface with a depth of 100 nm from the outermost surface, and it is confirmed that the same composition is within the range of quantitative accuracy with the sputtered surface with a depth of 20 nm.

  In the X-ray photoelectron spectroscopy (XPS), the X-ray source is MgKα (350 W), pass energy: 58.5 eV, measurement interval: 0.125 eV, photoelectron take-out angle to the sample surface: 45 deg, analysis area about Quantitative analysis was performed under the condition of 800 μmφ. As for the quantitative accuracy, the quantitative accuracy of N / (Si + W + N) is ± 2%, and the quantitative accuracy of W / (Si + W) is ± 1%.

(2) Evaluation of Bonding Energy of Si by XPS In the example of the present invention, the spectrum of Si2p was obtained by XPS, and the bonding energy of Si was measured from the peak position. The results are shown in Table 1. As an example, FIG. 3 shows a spectrum profile by XPS in Example 1 of the present invention. Further, for comparison with this example, the spectra of the bulk Si, Si ₃ N ₄ , and SiO ₂ by XPS are also shown by broken lines in FIG.

Chemical state analysis of X-ray photoelectron spectroscopy shows that, like amorphous, there is no long periodicity in the atomic arrangement and even if the atoms are arranged irregularly, the bonding state between atoms and the specific structure of the micro ( (Fine structure) can be evaluated. In any of the examples of the present invention, a spectrum is observed in which the peak of Si has a peak on the lower energy side than Si ₃ N ₄ . That is, as for the bonding state and structure between atoms of any amorphous Si-W-N film of the present invention, the crystal structure and bonding state similar to the Si ₃ N ₄ crystal structure are configured in a micro region. it is conceivable that. Further, it is considered that W enters the Si site in the crystal structure of Si ₃ N ₄ and the peak of the spectrum is shifted to the lower energy side, and it can be seen that W is dissolved in the silicon nitride crystal. Moreover, since the spectrum of Si2p is a single peak, no phase separation occurs, and the Si-W-N film is considered to be a single phase.

<Measurement of resistivity>
The specific resistance at 25 ° C. was measured by the four-terminal method (van der pauw method) for each of the amorphous films of the examples and comparative examples obtained by the reactive sputtering method. The results are shown in Table 1.

<B constant measurement>
The resistances at 25 ° C. and 50 ° C. of each film evaluation element were measured in a thermostat, and the B constant was calculated from the resistances at 25 ° C. and 50 ° C. The results are shown in Table 1.
As a result, it is confirmed that the examples of the present invention are thermistors having temperature characteristics that are more negative than the resistance values of 25 ° C. and 50 ° C., respectively. Regarding the results of these comparative examples and examples, a graph showing the B constant with respect to the specific resistance value at 25 ° C. is shown in FIG. 4, and a graph showing the B constant with respect to the composition ratio N / (Si + W + N) is shown in FIG.

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

As can be seen from these results, in each of the examples of the present invention, high specific resistance and B constant are obtained. Also, for materials having similar W / (Si + W) ratios, as the amount of nitriding (composition ratio N / (Si + W + N) increases, the specific resistance value and the B constant increase, ie, Si _x W _y N It is possible to adjust the thermistor characteristics by adjusting the nitridation amount of the _z film.
On the other hand, in Comparative Examples 1 and 2 of the amorphous Si-N film, the insulating property is too high, the specific resistance value is too large, the thermistor characteristic can not be obtained, and the B constant can not be measured. Moreover, since the comparative example 3 of the amorphous Si-W-N outside the composition range of the present invention used a Si-W alloy sputtering target, the amount of nitriding was small, and the specific resistance value and B constant were low.

<Evaluation of amorphousness by X-ray diffraction>
Next, the example of the present invention was an amorphous film, and it was confirmed that it was not a crystallized film using grazing incidence X-ray diffraction.
The oblique oblique incidence X-ray diffraction conditions were that the tube was Cu and the incident angle was 1 degree.
As a result, in each Example of the present invention, a peak showing crystallinity was not detected, and it was found to be amorphous.

The XRD profile of Example 1 of an amorphous Si-W-N film as an example is shown in FIG. As understood from these results, in Example 1 of the present invention, no peak indicating a crystallized film is detected.
In the graph, (*) is a peak derived from the device and from the Si substrate with a thermal oxide film, and it is confirmed that it is not a peak of the sample itself or a peak of the impurity phase. In addition, symmetry measurement (general θ-2θ measurement) was performed with an incident angle of 0 degree, and it was confirmed that the peak had disappeared. This is a peak derived from a device and a Si substrate with a thermal oxide film. It was confirmed.

The technical scope of the present invention is not limited to the above embodiment and examples, and various modifications can be made without departing from the spirit of the present invention.
For example, in the above embodiment, the pair of opposing electrodes is formed on the thin film thermistor portion, but the pair of opposing electrodes is formed below the thin film thermistor portion, that is, on one surface of the insulating film The thin film thermistor portion may be formed on the

  DESCRIPTION OF SYMBOLS 1 ... Thin film thermistor part, 2, 22 ... Base material, 5 ... Counter electrode, 10 ... Thermistor sensor

Claims (4)

Amorphous metal nitride represented by the general formula: Si _x W _y N _z (0 <y / (x + y) ≦ 0.30, 0.45 ≦ z / (x + y + z) ≦ 0.50, x + y + z = 1) The thermistor characterized by comprising. A substrate;
A thin film thermistor portion formed of the thermistor according to claim 1 on the substrate;
A thermistor sensor comprising: a pair of counter electrodes formed on at least one of the upper and lower sides of the thin film thermistor portion. The thermistor sensor according to claim 2,
The thermistor sensor, wherein the substrate is an insulating film. A method of manufacturing a thermistor according to claim 1, comprising
A thermistor manufacturing method comprising a film forming step of forming a film by performing reactive sputtering in a nitrogen-containing atmosphere using a sputtering target made of a mixed sintered body of Si ₃ N ₄ and W .