Thin-film thermistor and manufacturing method therefor

Abstract

[Problem] To provide a thin-film thermistor with excellent operational stability and a method for manufacturing the same. [Solution] A thin-film thermistor including: a substrate; an insulating film on the substrate surface; a heat-sensitive film on an inner side of an upper surface of the insulating film; a pair of lead electrodes connected to the heat-sensitive film and extending from the insulating film surface to the substrate surface; and an insulating protective film covering the heat-sensitive film. The thin-film thermistor further includes a glass protective film that covers the upper surface of the insulating protective film. A tip-end portion of a lead electrode located on the substrate surface is positioned outside the glass protective film, and an external electrode extends from an upper surface of the tip-end portion to the substrate surface. The manufacturing method includes: a step for forming an insulating film on a substrate surface of a substrate; a step for forming a pair of lead electrodes on top of the substrate surface; a step for forming a heat-sensitive film on top of the substrate surface; a step for forming an insulating protective film on top of the insulating film to cover the heat-sensitive film; a step for forming a glass protective film on top of the insulating protective film to cover an upper surface of the insulating protective film; and an external electrode formation step for forming an electrode film on top of the substrate to cover a tip-end portion of the lead electrode.

Description

Thin-film thermistor and method for manufacturing the same

[0001] The present invention relates to a thin-film thermistor comprising a multilayer structure in which multiple films including a heat-sensitive film are stacked, and to a method for manufacturing the same.

[0002] Among thermistor elements that measure temperature by measuring the electrical resistance of a heat-sensitive material that changes with temperature, thin-film thermistors are known, which consist of a multilayer structure made by stacking multiple films, including a heat-sensitive film.

[0003] For example, Patent Document 1 discloses a thin-film thermistor in which a heat-sensitive film is applied across a pair of electrodes formed on a substrate, and a sealing material is applied on top of this. In this thermistor, an insulating film is interposed between the substrate and the heat-sensitive film to prevent the substrate and the heat-sensitive film from reacting due to heat treatment during manufacturing. Furthermore, the electrodes are formed separately as an electrode pad that is in contact with the substrate and a terminal electrode that extends from the upper surface of the electrode pad to the heat-sensitive film and electrically connects the two. By selecting a material such as Pt that has excellent thermal stability with the heat-sensitive film for the terminal electrode, the reaction between the electrodes and the heat-sensitive film due to heat treatment during manufacturing is again prevented. It also describes providing a metal underlayment made of Ti, Cr, W, etc. between the substrate and the electrode pad to prevent the electrode pad from peeling off due to localized heating when attempting to connect a lead wire to the electrode pad.

[0004] Japanese Patent Publication No. 2007-066924

[0005] Incidentally, as mentioned above, a thin-film thermistor with excellent operational stability can be obtained by providing an insulating film between the substrate and the heat-sensitive film, and further by changing the electrodes. On the other hand, there is also a demand for higher resistance to thermal and mechanical loads when mounted on an electronic substrate, and as a result, excellent operational stability.

[0006] The present invention has been made in view of the above circumstances, and its object is to provide a thin-film thermistor with excellent operational stability and a method for manufacturing the same.

[0007] The thin-film thermistor according to the present invention comprises a substrate, an insulating film patterned on the substrate surface of the substrate, a heat-sensitive film formed on the inner side of the insulating film surface which is the upper surface of the insulating film and on the insulating film surface, a pair of lead electrodes electrically connected to the heat-sensitive film and extending from the insulating film surface to the substrate surface and patterned on the insulating film surface and the substrate surface, and an insulating protective film formed to cover the heat-sensitive film on the insulating film, further comprising a glass protective film made of glass covering the insulating protective surface which is the upper surface of the insulating protective film, wherein the tip portions of the lead electrodes on the substrate surface are located outside the glass protective film, and the external electrodes are formed extending from the upper surface of the tip portions to the substrate surface.

[0008] With these features, the lead electrode, which is electrically connected to the heat-sensitive film, is located below the glass protective film, while the tip of the lead electrode is positioned outside the glass protective film. Furthermore, the external electrode is formed extending from the upper surface of the tip of the lead electrode to the substrate surface. Therefore, the bonding strength between the external electrode and the substrate surface does not depend on the formation of the glass protective film, which is made of glass requiring high-temperature heat treatment. In addition, the bonding between the external electrode and the substrate surface prevents the tip of the lead electrode from peeling off the substrate. As a result, excellent operational stability is achieved.

[0009] In the above-described invention, the external electrode may be characterized by comprising a first layer made of at least one of Ti, Cr, Ni, W, Ta, Ni-Cr alloy, ruthenium, or ruthenium oxide, which electrically contacts the tip portion, and a second layer made of at least one of Pt, Au, Pd, palladium alloy, Ag, Cu, or Cu alloy, which is laminated on the first layer. Furthermore, in the above-described invention, an external connection electrode pad may be provided on the substrate surface of the substrate so as to be in electrical contact with the external electrode. Furthermore, the external connection electrode pad may be characterized by being made of at least one of Au, Ni, Pd, Ag, or Ni alloy. According to such features, the bonding strength between the external electrode and the substrate surface is excellent, and as a result, the operational stability is excellent.

[0010] In the invention described above, the extraction electrode may be characterized by having an insertion portion inserted between the substrate surface of the substrate and the heat-sensitive film. With this feature, the physical contact stability between the heat-sensitive film and the extraction electrode is excellent, and as a result, the operational stability is excellent.

[0011] In the above-described invention, the extraction electrode may be characterized by being made of at least one metal thin film of Pt, Au, Pd, or a palladium alloy. According to this feature, the chemical contact stability between the heat-sensitive film and the extraction electrode is excellent, and as a result, the operational stability is excellent.

[0012] In the invention described above, the glass protective film may be characterized in that it is in contact with the extraction electrode on the outside of the insulating protective film. With this feature, the insulating protective film can be protected more stably, and as a result, the operational stability is excellent.

[0013] Furthermore, the manufacturing method of a thin-film thermistor according to the present invention includes a substrate, an insulating film patterned on the substrate surface of the substrate, a heat-sensitive film formed on the inner side of the insulating film surface which is the upper surface of the insulating film and on the insulating film surface, a pair of lead electrodes electrically connected to the heat-sensitive film and extending from the insulating film surface to the substrate surface and patterned on the insulating film surface and the substrate surface, and an insulating protective film formed so as to cover the heat-sensitive film on the insulating film, further including a glass protective film made of glass covering the insulating protective surface which is the upper surface of the insulating protective film, the tip portions of the lead electrodes on the substrate surface are located outside the glass protective film, and the external electrodes are formed extending from the upper surface of the tip portions to the substrate surface. A manufacturing method comprising: an insulating film forming step of forming an insulating layer made of an insulating material on the substrate surface of the substrate and patterning it to form the insulating film; an extraction electrode forming step of forming a pair of extraction electrodes by forming a metal film made of a conductive material on the substrate surface of the substrate and patterning it; a thermal film forming step of forming a thermal layer made of a thermal-sensitive material on the substrate surface of the substrate and patterning it to form the thermal-sensitive film; an insulating protective film forming step of forming an insulating protective film made of an insulating material on the insulating film so as to cover the thermal-sensitive film; a glass protective film forming step of applying glass paste on the insulating protective film so as to cover the upper surface of the insulating protective film and heat-treating it to form a glass protective film; and an external electrode forming step of forming an electrode film made of a conductive material on the substrate so as to cover the tip portion of the extraction electrode.

[0014] According to these features, the lead electrode, which is electrically connected to the heat-sensitive film, is located below the glass protective film, while the tip of the lead electrode is positioned outside the glass protective film. Furthermore, the external electrode is formed extending from the upper surface of the tip of the lead electrode to the substrate surface. As a result, the external electrode formation process can be performed after the glass protective film formation process, and the bonding strength between the external electrode and the substrate surface does not depend on the glass protective film formation process, which requires high-temperature heat treatment. In addition, the external electrode formation process, which bonds the external electrode to the substrate surface, also prevents the tip of the lead electrode from peeling off from the substrate. As a result, excellent operational stability is achieved.

[0015] In the invention described above, the thin-film thermistor may include an external connection electrode pad provided on the substrate surface of the substrate so as to be in electrical contact with the external electrode, and may also include an electrode pad formation step following the external electrode formation step, in which an electrode film made of a conductive material is patterned on the substrate and on the external electrode. According to this feature, long-term reliability of electrical characteristics can be obtained, and as a result, excellent operational stability can be achieved.

[0016] In the invention described above, the glass protective film may be characterized in that it is in contact with the extraction electrode on the outside of the insulating protective film. With this feature, the insulating protective film can be protected more stably, and as a result, the operational stability is excellent.

[0017] This is a top view of a thin-film thermistor according to one embodiment of the present invention. This is a flow chart showing a method for manufacturing the thin-film thermistor. This is a cross-sectional view showing part of the manufacturing process of the thin-film thermistor. This is another cross-sectional view showing part of the manufacturing process of the thin-film thermistor. This is a plan view of a thin-film thermistor with a different shape of extraction electrode. This is a cross-sectional view of a thin-film thermistor according to another embodiment of the present invention. This is a table showing the results of the peel strength test of the external electrode. This is a cross-sectional view of a comparative example thin-film thermistor used in the peel strength test.

[0018] Hereinafter, a thin-film thermistor according to an embodiment of the present invention will be described with reference to Figures 1 to 6. In each figure, the scale of each component has been appropriately changed for explanatory purposes in order to make each component recognizable. Also, the same or equivalent parts are denoted by the same reference numeral, and redundant explanations may be omitted.

[0019] <First Embodiment> The first embodiment will be described with reference to Figures 1 to 5.

[0020] Figure 1 is a plan view of a thin-film thermistor according to this embodiment. As shown in the figure, the thin-film thermistor 1 includes a substrate 2, an insulating film 7a patterned on the substrate surface 2a of the substrate 2, and a heat-sensitive film 10a formed on the inside of the insulating film surface 7b, which is the upper surface of the insulating film 7a when viewed from above, and on the insulating film surface 7b. The thin-film thermistor 1 further includes a pair of lead electrodes 9a, 9b that are electrically connected to the heat-sensitive film 10a and extend from the insulating film surface 7b to the substrate surface and are patterned on the insulating film surface 7b and the substrate surface 2a, an insulating protective film 11 formed to cover the heat-sensitive film 10a on the insulating film 7a, a glass protective film 12 made of glass that covers the insulating protective surface, which is the upper surface of the insulating protective film 11, and a pair of external electrodes 5a, 5b.

[0021] Here, the external electrodes 5a and 5b are positioned on the outside of the glass protective film 12, facing each other on the left and right sides of the paper, and are in contact with the lead electrodes 9a and 9b. In other words, the lead electrodes 9a and 9b extend to the outside of the glass protective film 12. To put it another way, the lead electrodes 9a and 9b have their tips 9a-1 and 9b-1 positioned on the outside of the glass protective film 12, and the external electrodes 5a and 5b are connected to these tips 9a-1 and 9b-1. Furthermore, the external electrodes 5a and 5b are formed to extend from the tips 9a-1 and 9b-1 of the lead electrodes 9a and 9b to the substrate surface 2a. Note that the glass protective film 12 is positioned on top of the insulating protective film 11 so as not to come into contact with the lead electrodes 9a and 9b. Furthermore, even if the glass protective film 12 extends beyond the insulating protective film 11 and comes into contact with the lead electrodes 9a and 9b, it is sufficient that it is positioned inside the tip portions 9a-1 and 9b-1 and does not obstruct the connection between the tip portions 9a-1 and 9b-1 and the external electrodes 5a and 5b. By allowing the glass protective film 12 to extend beyond the insulating protective film 11, the insulating protective film 11 can be protected more stably. In addition, the tip portions 9a-1 and 9b-1 of the lead electrodes 9a and 9b are positioned on the substrate surface 2a outside the insulating film surface 7b.

[0022] Next, with reference to Figure 2, the manufacturing method of the thin-film thermistor 1 will be explained with reference to Figures 3 and 4.

[0023] First, an insulating film 7a made of an insulating material is formed on the substrate surface 2a of the substrate 2 (insulating film formation step: S1). Specifically, silicon dioxide (SiO₂) is formed on one surface of the polished substrate 2 using sputtering, plasma CVD, etc. ２ ), silicon nitride (Si ３ N ４ An insulating layer 7 made of the above is formed to a thickness of 0.1 to 0.5 μm (Figure 3(a)). Then, the insulating layer 7 is patterned using a photoetching method to form an insulating film 7a (Figure 3(b)).

[0024] The substrate 2 is selected from, for example, insulating substrates such as ceramic substrates made of alumina, aluminum nitride, zirconia, quartz, mullite, steatite, etc., sapphire substrates, and glass substrates made of glass materials that suppress deformation due to phase transitions within the operating temperature range, or semiconductor substrates such as silicon substrates, with a thickness of approximately 10 to 300 μm. Preferably, the surface of the substrate 2 is polished to a smoothness of 0.05 μm or less.

[0025] Next, extraction electrodes 9a and 9b are formed (extraction electrode formation step: S2). First, at least one metal thin film layer 9 made of a chemically stable metal material such as platinum (Pt), palladium (Pd) or palladium alloy, or gold (Au) is deposited on the substrate 2 and the insulating film 7a by sputtering, ion plating, or vapor deposition (Figure (c)). Next, the deposited metal thin film layer 9 is patterned using a photoetching method to form a pair of extraction electrodes 9a and 9b that are in contact with the substrate 2 and the insulating film 7a and face each other (Figure (d)).

[0026] In this embodiment, the case where the leading electrodes 9a and 9b are formed after the insulating film 7a is formed is shown, but the insulating film 7a may be provided after the leading electrodes 9a and 9b are patterned on the substrate 2.

[0027] Next, a heat-sensitive film 10a is formed using a heat-sensitive material (heat-sensitive film formation step: S3). The heat-sensitive layer 10 is formed to a thickness of 0.3 to 2.0 μm by sputtering or the like, so as to cover a portion of the lead electrodes 9a and 9b formed in the previous step and the insulating film 7a (Figure (e)). A portion of the lead electrodes 9a and 9b becomes an insertion portion inserted between the substrate surface 2a of the substrate 2 and the heat-sensitive film 10a and insulating film 7a. This provides excellent physical contact stability between the heat-sensitive film 10a and the lead electrodes 9a and 9b.

[0028] The heat-sensitive layer 10 is patterned using a patterning method to form a heat-sensitive film 10a on the insulating film 7a between the extraction electrodes 9a and 9b, and then heat-treated (Figure 4(a)). In detail, the heat-sensitive layer 10 is formed on a substrate using a sputtering method, targeting a sintered body of a composite oxide consisting of manganese, nickel, cobalt, iron, etc. After that, the patterned heat-sensitive film 10a is heat-treated by holding it at a heating temperature of, for example, 400 to 1200°C for 1 to 5 hours. The electrical properties of the heat-sensitive film 10a, such as the resistance-temperature characteristics, can be adjusted by, for example, the thickness of the heat-sensitive film. In adjusting the thickness of the heat-sensitive film, a second heat-sensitive film (not shown) may be patterned and laminated after the heat-sensitive film 10a is formed.

[0029] Furthermore, the stacking relationship between the thermal film and the extraction electrodes can be arbitrary. For example, when a second thermal film is patterned on the thermal film 10a as described above, extraction electrodes 9a and 9b can be formed between them, creating a structure where the thermal film sandwiches the second thermal film. Alternatively, the thermal film 10a can be patterned first, and then the extraction electrodes 9a and 9b can be formed so that they contact the upper surface of the thermal film 10a, or the thermal film 10a can be sandwiched between the extraction electrodes 9a and 9b and a second extraction electrode (not shown), resulting in a stacked structure of the thermal film and multiple extraction electrodes.

[0030] Next, an insulating protective film 11 is patterned to protect the heat-sensitive film 10a (insulating protective film formation step: S4). The insulating protective film 11 is, for example, silicon dioxide (SiO₂) with a thickness of 0.2 to 2.0 μm. ２ ), silicon nitride (Si ３ N ４), etc. Further, a glass protective film 12 is formed to cover the upper surface of the insulating protective film 11 (glass protective film forming step: S5) (FIG. 4(b)). Here, the insulating protective film 11 and the glass protective film 12 are formed so as to cover a part of the heat-sensitive film 10a and the extraction electrodes 9a, 9b. That is, the insulating protective film 11 and the glass protective film 12 are formed so as to expose other parts of the extraction electrodes 9a, 9b. The glass protective film 12 is formed by applying glass paste by means such as screen printing and then performing heat treatment at 400 to 800°C. This makes it possible to reduce the influence of the external atmosphere on the heat-sensitive film 10a, for example, by protecting the heat-sensitive film 10a from moisture and improving the moisture resistance of the thin-film thermistor 1. It is also preferable that the glass protective film 12 is formed simultaneously with the insulating protective film 11 because this simplifies the manufacturing process. For example, silicon dioxide (SiO ２ ), silicon nitride (Si ３ N ４ ), after forming an insulating protective layer made of such materials and a glass film layer, the insulating protective film 11 and the glass protective film 12 can be formed simultaneously by patterning via photoetching.

[0031] Next, external electrodes 5a and 5b are formed (external electrode forming step: S6). The external electrodes 5a and 5b are formed by laminating a first electrode film 3 as a first layer and a second electrode film 4 as a second layer laminated thereon. Specifically, the first electrode film 3 and the second electrode film 4 are sequentially formed on the extraction electrodes 9a, 9b, the substrate 2, and the glass protective film 12 by a method such as sputtering or vapor deposition (FIG. 4(c)). The total thickness of the first electrode film 3 and the second electrode film 4 can be, for example, about 0.1 to 0.5 μm. Further, the first thin electrode film 3 is made of at least one selected from the group consisting of Ti, Cr, Ni, W, Ta, Ni-Cr alloy, ruthenium, and ruthenium oxide, for example. On the other hand, the second electrode film 4 is made of at least one selected from the group consisting of Pt, Au, Pd, palladium alloy, Ag, Cu, Cu alloy, etc., for example. In the present embodiment, it is also possible to use metals that are easily oxidized by heating and could not be used in conventional methods, such as Ag, Cu, and Cu alloys.

[0032] Next, unnecessary portions of the first electrode film 3 and the second electrode film 4 are removed by photoetching, and the external electrodes 5a and 5b, consisting of the first electrode films 3a and 3b and the second electrode films 4a and 4b, are patterned to cover the tip portions 9a-1 and 9b-1 (Figure 4(d)).

[0033] As described above, the lead electrodes 9a and 9b, which are electrically connected to the heat-sensitive film 10a, are located below the glass protective film 12, with the tips 9a-1 and 9b-1 of the lead electrodes 9a and 9b positioned outside the glass protective film 12, and the external electrodes 5a and 5b are formed extending from the upper surface of the tips 9a-1 and 9b-1 to the substrate surface 2a. Therefore, when forming the thin-film thermistor 1 as a laminate, the external electrode formation step S6 can be a later step than the glass protective film formation step S5. As a result, the external electrodes 5a and 5b are not affected by the heat treatment associated with the glass protective film formation step S5 or other steps. For example, the heat treatment after the formation of the external electrodes 5a and 5b is only performed once, which is required for the formation of the external electrodes 5a and 5b. In other words, the bonding strength between the external electrodes 5a and 5b and the substrate surface 2a does not depend on the formation of the glass protective film 12, which requires high-temperature heat treatment. As a result, the thin-film thermistor 1 has external electrodes 5a and 5b, which are bonded to the upper surfaces of the tips 9a-1 and 9b-1 of the lead electrodes 9a and 9b, also bonded to the substrate surface 2a. Therefore, delamination of the tips 9a-1 and 9b-1 of the lead electrodes 9a and 9b from the substrate 2 can be prevented. As a result, the thin-film thermistor 1 has excellent operational stability.

[0034] Furthermore, the thin-film thermistor 1' with a different shape of extraction electrodes, as shown in Figure 5, also exhibits similarly excellent operational stability. In the thin-film thermistor 1 described above, the extraction electrodes 9a and 9b formed on the insulating film surface of the insulating film 7a were arranged with their opposing sides parallel. However, in the thin-film thermistor 1' shown in the same figure, the extraction electrodes 9a' and 9b' are comb-shaped. They are arranged so that the comb teeth face each other and interlock alternately. The tips 9a-1 and 9b-1 of the extraction electrodes 9a and 9b extend to the outside of the glass protective film 12, and the external electrodes 5a and 5b are positioned outside the glass protective film 12 and connected to the tips 9a-1 and 9b-1.

[0035] <Second Embodiment> The second embodiment will be described with reference to Figure 6.

[0036] Figure 6 is a cross-sectional view showing the final state of one embodiment of the manufacturing process for the thin-film thermistor 21 of the second embodiment. Due to the convenience of the connection method with external lead wires (not shown), external connection electrode pads 13a and 13b may be formed on the external electrodes 5a and 5b of the thin-film thermistor 1 manufactured in the first embodiment. For example, when connecting external lead wires to the thin-film thermistor 21 with solder, the bonding strength with the external lead wires can be improved by forming the external connection electrode pads on the external electrodes 5a and 5b with one of the metals that form an intermetallic compound with tin (Sn), the main component of solder, such as gold (Au), silver (Ag), palladium (Pd), copper (Cu), or nickel (Ni). As a result, the thin-film thermistor 21 exhibits excellent operational stability.

[0037] For example, external connection electrode pads 13a and 13b, with a thickness of 5 to 30 μm, are patterned to cover the external electrodes 5a and 5b, and are made of at least one conductive material such as gold (Au), nickel (Ni), palladium (Pd), silver (Ag), or a Ni alloy. Silver (Ag) is formed by applying a silver paste using means such as screen printing, followed by heat treatment, while gold (Au), nickel (Ni), palladium (Pd), or a Ni alloy is patterned by plating to form the external connection electrode pads 13a and 13b. In this case, the electrode pad formation step is included immediately following the external electrode formation step (S6). In other words, the external connection electrode pads 13a and 13b are provided on the substrate 2 by patterning an electrode film made of a conductive material on the external electrodes 5a and 5b.

[0038] Furthermore, among the various combinations of metal thin film layers that form the electrodes, when titanium (Ti) is used as the first electrode films 3a and 3b, platinum (Pt) is used as the second electrode films 4a and 4b and the extraction electrodes 9a and 9b, and at least one of nickel alloy, gold (Au), or silver (Ag) is used for the external connection electrode pads 13a and 13b that serve as electrodes for external connection, excellent performance can be obtained in terms of long-term reliability of electrical characteristics and mechanical testing.

[0039] The structure of the thin-film thermistor described above shows the structure of a thin-film thermistor as a single element. However, a thin-film thermistor aggregate substrate may be formed by arranging a large number of thin-film thermistors having the same structure on a single substrate. To cut and separate the thin-film thermistor aggregate substrate into individual thin-film thermistor chips, the aggregate substrate is attached to a dicing tape or the like and then cut using a laser scriber, a dicing saw, or the like. Individual thin-film thermistor chips are formed in this manner.

[0040] <Peel Strength Test for External Electrodes> Next, a peel strength test for evaluating the adhesion of external electrodes to a substrate will be described with reference to FIGS. 7 and 8. FIG. 7 is a table listing the results of the peel strength test.

[0041] In the table, "Working Example" uses the thin-film thermistor 21 shown in the above-described second working example (see FIG. 6). The thin-film thermistor 21 is obtained by forming the external electrodes 5a and 5b after forming the glass protective film 12. On the other hand, "Comparative Example" uses the thin-film thermistor 31 shown in FIG. 8. The thin-film thermistor 31 is obtained by forming the external electrodes 5a and 5b before forming the heat-sensitive film 10a. The peel strength of the external electrodes was measured for these thin-film thermistors. The peel strength was measured by a shear strength test in which the external electrode of the mounted thin-film thermistor is pushed laterally along the substrate surface 2a of the substrate 2 to cause peeling. The shear strength test was performed 16 times each for the working example and the comparative example, and the average value is shown, with the maximum value and the minimum value also shown for reference. A comparison between the working example and the comparative example shows that the working example has higher peel strength for the external electrodes 5a and 5b. That is, it can be seen that reducing the heat input to the external electrodes during thermal history can increase the bonding strength between the substrate 2 and the external electrodes 5a and 5b.

[0042] In other words, as described above, by disposing the external electrodes outside the glass protective film and setting the external electrode forming step as a step after the glass protective film forming step, the heat input to the external electrodes can be reduced, and the bonding strength of the external electrodes to the substrate can be increased, as compared with the case where the order of the steps is reversed. As a result, the thin-film thermistor is excellent in operational stability.

[0043] So far, the embodiments according to the present invention and modifications based thereon have been described, but the present invention is not necessarily limited to these examples. Further, those skilled in the art will be able to find various alternative embodiments and modifications without departing from the gist of the present invention or the scope of the appended claims.

[0044] 1 Thin film thermistor 2 Substrate 2a Substrate surface 5a, 5b External electrodes 7a Insulating film 9a, 9b Extraction electrodes 10a Thermosensitive film 11 Insulating protective film 12 Glass protective film

Claims

1. A thin-film thermistor comprising: a substrate; an insulating film patterned on the substrate surface of the substrate; a heat-sensitive film formed on the inner side of the insulating film surface, which is the upper surface of the insulating film, and on the insulating film surface; a pair of lead electrodes electrically connected to the heat-sensitive film and extending from the insulating film surface to the substrate surface, with the lead electrodes patterned on the insulating film surface and the substrate surface; and an insulating protective film formed to cover the heat-sensitive film on the insulating film, wherein the thin-film thermistor further comprises a glass protective film made of glass covering the insulating protective surface, which is the upper surface of the insulating protective film, the tip portions of the lead electrodes on the substrate surface are located outside the glass protective film, and the external electrodes are formed extending from the upper surface of the tip portions to the substrate surface.

2. The thin-film thermistor according to claim 1, characterized in that the external electrode comprises a first layer made of at least one of Ti, Cr, Ni, W, Ta, Ni-Cr alloy, ruthenium, and ruthenium oxide, which is in electrical contact with the tip, and a second layer made of at least one of Pt, Au, Pd, palladium alloy, Ag, Cu, or Cu alloy, which is laminated on the first layer.

3. The thin-film thermistor according to claim 1, characterized in that it includes an external connection electrode pad provided on the substrate surface of the substrate so as to be in electrical contact with the external electrode.

4. The thin-film thermistor according to claim 3, characterized in that the external connection electrode pad is made of at least one of Au, Ni, Pd, Ag, and Ni alloy.

5. The thin-film thermistor according to claim 1, characterized in that the extraction electrode has an insertion portion inserted between the substrate surface of the substrate and the heat-sensitive film.

6. The thin-film thermistor according to claim 5, characterized in that the extraction electrode is made of at least one metal thin film of Pt, Au, Pd, and palladium alloy.

7. The thin-film thermistor according to claim 1, characterized in that the glass protective film is in contact with the extraction electrode outside the insulating protective film.

8. A method for manufacturing a thin film thermistor comprising: a substrate; an insulating film patterned on the substrate surface of the substrate; a heat-sensitive film formed on the inner side of the insulating film surface, which is the upper surface of the insulating film, and on the insulating film surface; a pair of lead electrodes electrically connected to the heat-sensitive film and extending from the insulating film surface to the substrate surface, with the lead tips of the lead electrodes located on the substrate surface being outside the glass protective film, and the external electrodes extending from the upper surface of the lead tips to the substrate surface, the method comprising: an insulating film forming step of forming an insulating layer made of an insulating material on the substrate surface of the substrate and patterning it to form the insulating film; and a lead electrode forming step of forming a pair of lead electrodes on the substrate surface of the substrate and patterning it. A method for manufacturing a thin-film thermistor, comprising: a heat-sensitive film forming step of forming a heat-sensitive layer made of a heat-sensitive material on the substrate surface of the substrate and patterning it to form the heat-sensitive film; an insulating protective film forming step of patterning an insulating protective film made of an insulating material on the insulating film so as to cover the heat-sensitive film; a glass protective film forming step of applying glass paste on the insulating protective film so as to cover the upper surface of the insulating protective film and heat treating it to form a glass protective film; and an external electrode forming step of patterning an electrode film made of a conductive material on the substrate so as to cover the tip portion of the lead electrode.

9. The method for manufacturing a thin film thermistor according to claim 8, wherein the thin film thermistor includes an external connection electrode pad provided on the substrate surface of the substrate so as to be in electrical contact with the external electrode, and the method for manufacturing a thin film thermistor according to claim 8 is characterized in that, following the external electrode formation step, an electrode pad formation step is performed in which an electrode film made of a conductive material is patterned on the substrate and on the external electrode.

10. The method for manufacturing a thin-film thermistor according to claim 8, characterized in that the glass protective film is in contact with the extraction electrode outside the insulating protective film.

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