Thin film type NTC thermistor

Abstract

The utility model relates to NTC thermistor technical field, concretely relates to a film type NTC thermistor, including the substrate, insulating layer, adhesion layer, alloy thermosensitive film, electrode film, first protective layer and second protective layer that set up successively, electrode film is not covered alloy thermosensitive film at electrode pattern place, and electrode pattern will electrode film interval into first electrode film and second electrode film, wherein, at the both sides of electrode pattern, first electrode film and second electrode film cover alloy thermosensitive film and adhesion layer respectively.

Description

Technical Field

[0001] This utility model relates to the field of NTC thermistor technology, and in particular to a thin-film NTC thermistor. Background Technology

[0002] NTC thermistors are composed of two or more transition metal oxides such as Mn, Co, Ni, Zn, Cu, and Fe, as well as doped with variable-valence metals such as Ti, Cr, Mg, Al, and Ca. The conductivity of transition metal oxide materials is similar to that of semiconductors such as silicon. At lower temperatures, the number of charge carriers is relatively small, resulting in a higher resistance. As the temperature gradually increases, the charge carriers inside the material are activated, their number gradually increases, and the resistance decreases. Therefore, NTC thermistors exhibit the characteristic of decreasing resistance with increasing temperature, making them widely used in temperature measurement, compensation, surge current control, and liquid level measurement.

[0003] Currently, most thin-film NTC thermistors use, for example... Figure 4 The bottom electrode structure shown is prone to gaps at the interface between the electrode film and the alloy thermistor film due to the different thermal expansion of the materials between the layers. The alloy thermistor film is subjected to tensile stress from the electrode, resulting in an open circuit or high resistance in the product. Utility Model Content

[0004] This utility model provides a thin-film NTC thermistor to solve the problem that most current thin-film NTC thermistors use a bottom electrode structure, resulting in open circuits or high resistance values.

[0005] This utility model discloses a thin-film NTC thermistor, comprising a substrate, an insulating layer, an adhesive layer, an alloy thermistor film, an electrode, a first protective layer, and a second protective layer stacked sequentially; the electrode film does not cover the alloy thermistor film at the electrode pattern, and the electrode pattern divides the electrode film into a first electrode film and a second electrode film; wherein, on both sides of the electrode pattern, the first electrode film and the second electrode film are respectively covered by the alloy thermistor film and the adhesive layer.

[0006] Optionally, the electrode pattern is a bent shape.

[0007] Optionally, the electrode pattern is arc-shaped.

[0008] Optionally, the insulating layer is a silicon oxide layer or a silicon nitride film layer.

[0009] Optionally, the thickness of the insulating layer is 10-1000 nm.

[0010] Optionally, the thickness of the insulating layer is 500 nm.

[0011] Optionally, the arc shape is a single-bend arc shape.

[0012] Optionally, the arc shape can be a wave shape.

[0013] This invention employs a top electrode structure, where the electrode pattern divides the electrode film into a first electrode film and a second electrode film. On both sides of the electrode pattern, the first electrode film and the second electrode film are respectively covered with an alloy thermistor film and an adhesive layer. This avoids the problem of gaps, delamination, cracking, and deformation of the alloy thermistor film due to the different thermal expansion of the alloy thermistor film and the electrode after heat treatment, which could lead to open circuits or high resistance values ​​in the product. This ensures the consistent performance of the NTC thermistor. Attached Figure Description

[0014] The technical solution of this utility model will be further described in detail below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0015] Figure 1 This is a simplified perspective view of a thin-film NTC thermistor according to an embodiment of this utility model from a top view perspective; Figure 2 This is a schematic diagram of the electrode pattern of an embodiment of this utility model; Figure 3 This is a schematic diagram of the electrode pattern of an embodiment of this utility model; Figure 4 This is a schematic diagram of the bottom electrode of an NTC thermistor; Figure 5 This is a schematic diagram of the top electrode of the NTC thermistor according to an embodiment of the present invention; Figure 6 This is a schematic diagram of the resistance-temperature relationship of a thin-film NTC thermistor according to Embodiment 1 of this utility model; Figure 7 This is the XRD pattern of the thin-film NTC thermistor alloy thermistor film layer of Embodiment 1 of this utility model; Figure 8 The performance (R) of the products in Embodiments 1 to 3 of this utility model 25 (Data diagram, in which the electrode pattern of Example 1 is wavy;) Figure 9 The product performance (B) of Embodiments 1 to 3 of this utility model 25 / 50 (Data diagram, in which the electrode pattern of Example 1 is wavy;) Figure 10 The performance (R) of products prepared with different electrode patterns (straight line, single bend, wave) in Embodiment 1 of this utility model is evaluated. 25 Data chart; Figure 11 The performance (B) of products prepared with different electrode patterns (straight line, single bend, wave) in Embodiment 1 of this utility model is evaluated. 25 / 50 Data chart; Figure 12 In Embodiment 1 of this utility model, the Mn-Co-Ni-O system NTC thermistor operates at 200°C. 25 / 50 Curve of rate of change over storage time; Figure 13 The Mn-Co-Ni-O system NTC thermistor in Embodiment 1 of this utility model, at 200℃, R 25 Curve of rate of change over storage time; Figure 14 In Embodiment 4 of this utility model, the Mn-Co system NTC thermistor operates at 200°C. 25 / 50 Curve of rate of change over storage time; Figure 15 In Embodiment 4 of this utility model, the Mn-Co system NTC thermistor at 200℃ R 25 Curve of rate of change over storage time; Figure 16 In Embodiment 5 of this utility model, the Mn-Ni system NTC thermistor operates at 200°C. 25 / 50 Curve of rate of change over storage time; Figure 17 In Embodiment 5 of this utility model, the Mn-Ni system NTC thermistor at 200℃ R 25 Curve of rate of change over storage time; Figure 18 In Embodiment Six of this utility model, the Mn-Co-Ni-Al system NTC thermistor operates at 200°C. 25 / 50 Curve of rate of change over storage time; Figure 19 The Mn-Co-Ni-Al system NTC thermistor in Embodiment Six of this utility model, at 200℃, R 25 The rate of change over storage time.

[0016] The labels for the attached figures are as follows: 110. Substrate; 120. Insulating layer; 130. Adhesive layer; 140. Thermistor film; 150a. First electrode film; 150b. Second electrode film; 160. First protective layer; 170. Second protective layer; 180. Electrode pattern. Detailed Implementation

[0017] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The preferred embodiments of this utility model will now be described in detail with reference to the accompanying drawings.

[0018] This utility model embodiment provides a thin-film NTC thermistor, such as Figure 1 and Figure 5 As shown, it includes a substrate, an insulating layer, an adhesive layer, an alloy thermistor film, an electrode film, a first protective layer, and a second protective layer stacked sequentially; the electrode film does not cover the alloy thermistor film at the electrode pattern, and the electrode pattern divides the electrode film into a first electrode film and a second electrode film; wherein, on both sides of the electrode pattern, the first electrode film and the second electrode film are respectively covered by the alloy thermistor film and the adhesive layer.

[0019] like Figure 5 As shown, this utility model adopts a top electrode structure, that is, after the electrode pattern divides the electrode film into a first electrode film and a second electrode film, the first electrode film and the second electrode film are respectively covered with an alloy thermistor film and an adhesive layer on both sides of the electrode pattern. This can avoid the problem of gaps, delamination, cracking and deformation of the alloy thermistor film due to the different thermal expansion of the alloy thermistor film and the electrode after heat treatment, which would lead to open circuit or high resistance in the product, thus ensuring the consistency of NTC thermistor performance.

[0020] In contrast, such as Figure 4 In the bottom electrode structure shown, the interface between the electrode film and the alloy thermistor film is prone to gaps due to the different thermal expansion of the materials between the layers. The alloy thermistor film is subjected to tensile stress from the electrode (the alloy thermistor film is a ceramic material with typical characteristics of high compressive strength and low tensile strength), resulting in open circuits or high resistance in the product.

[0021] Specifically, the electrode pattern is a bent shape, or like... Figure 2 and Figure 3 As shown, the electrode pattern is arc-shaped. The electrode pattern etched from the electrode film adopts a bent or arc-shaped design, with chamfered corners to disperse stress and increase the conduction path, combining the advantages of high pattern accuracy, reliable electrical performance, and flexible resistance adjustment. More specifically, the arc shape is a single-bend arc shape, or the arc shape is a wave shape.

[0022] More specifically, the insulating layer is a silicon oxide layer or a silicon nitride film layer. The thickness of the insulating layer is 10-1000 nm, specifically, the thickness of the insulating layer is 500 nm.

[0023] The method for preparing a thin-film NTC thermistor of this invention includes the following steps: Clean the substrate; Forming an insulating layer: An insulating layer is formed on the surface of the substrate to isolate the substrate from conductivity; Forming an adhesion layer: An adhesion layer is formed on the insulating layer to enhance the adhesion of the substrate; Preparation of alloy thermistor thin films: Mn-Co-Ni ternary system, Mn-Co binary system, Mn-Ni binary system, or Mn-Co-Ni-Al quaternary system target materials are sputtered onto the adhesion layer using magnetron sputtering. Then, patterning is performed using laser technology to obtain the alloy thermistor thin film. The alloy thermistor thin film partially covers the adhesion layer. Specifically, after the alloy thermistor thin film is sputtered onto the adhesion layer, since it completely covers the adhesion layer and has the same size as the adhesion layer, patterning is then performed using laser technology to obtain the alloy thermistor film layer of the actual required size and shape, such as a rectangular alloy thermistor film layer of a certain size.

[0024] Preparation of electrode thin films: Electrode thin films containing one or more metal materials, including silver, gold, platinum, titanium, tungsten, and their alloys, are formed on an alloy thermistor thin film by sputtering. Then, electrode patterns are etched on the electrode thin films by laser etching to form bent or arc-shaped patterns that expose the alloy thermistor thin films. The electrode thin films are divided into a first electrode thin film and a second electrode thin film by the electrode patterns. On both sides of the electrode patterns, the first electrode thin film and the second electrode thin film are respectively covered by an alloy thermistor thin film and an adhesive layer. After a portion of the electrode film is etched away by a laser, the alloy thermistor film is exposed. The etched area is the electrode pattern, which can be bent or arc-shaped.

[0025] Annealing treatment: The NTC thermistor with prepared electrodes is subjected to hot annealing in an air atmosphere sintering furnace to crystallize the sputtered alloy thermistor film. After annealing, the alloy thermistor film crystallizes to form a manganese cobalt nickel oxide film. Only at this point does the alloy thermistor film possess thermistor properties. Therefore, the annealed alloy thermistor film can also be called a manganese cobalt nickel oxide film or an NTC thermistor film.

[0026] Forming the first protective layer: A first protective layer covering the alloy thermistor film is formed at the electrode pattern to ensure the stability of the thermistor film; Forming a second protective layer: A second protective layer is formed on the first protective layer to improve the moisture resistance and acid and alkali resistance of the heat-sensitive film.

[0027] Specifically, the steps for forming the insulating layer are as follows: a silicon oxide layer or silicon nitride film layer with a thickness of 10-1000nm is formed on the substrate surface as an insulating layer by using sputtering or thermal oxidation processes to isolate the substrate from conductivity.

[0028] Specifically, the steps for forming the adhesion layer are as follows: Select any one of Ti, Ni, or W as the material, and sputter the adhesion layer onto the insulating layer to enhance the adhesion between the electrode layer, the alloy thermistor thin film layer, and the substrate. The pre-evacuation vacuum degree is 2.5 × 10⁻⁶. -3Pa, power 60-200W, heating temperature 25℃-400℃; sputtering time 10-30min.

[0029] Specifically, the steps for preparing the alloy thermistor thin film are as follows: Mn-Co-Ni ternary, Mn-Co binary, Mn-Ni binary, or Mn-Co-Ni-Al quaternary target materials are sputtered onto the adhesion layer using magnetron sputtering, followed by patterning using laser technology to obtain the alloy thermistor thin film. The sputtering power is 60-200W, and the pre-evacuation vacuum degree is 2.5 × 10⁻⁶. - 3 Pa, sputtering atmosphere O2 and Ar2, controlling the oxygen-argon volume ratio between 0.1 and 3.0, sputtering temperature 25℃-400℃, sputtering time 30-200min.

[0030] Specifically, in the electrode thin film preparation step, the sputtering power is 60-200W, and the pre-evacuation degree is 2.5×10⁻⁶. -3 Pa, sputtering temperature 25℃-400℃.

[0031] Specifically, in the annealing process, the annealing temperature is 400-1000℃ and the annealing time is 0.5h-12h.

[0032] Specifically, the steps for forming the first protective layer are as follows: using silicon dioxide or silicon nitride as the material, a first protective layer covering the alloy thermistor film is formed on the electrode pattern through sputtering or screen printing processes to isolate the outside air and ensure the stability of the thermistor film.

[0033] Specifically, the step of forming the second protective layer involves selecting silicone resin or other resins as materials. The second protective layer does not completely cover the first and second electrode films to facilitate subsequent welding and encapsulation. Other resins can include epoxy resin. Silicone resin has excellent high-temperature resistance and weather resistance, and can withstand temperatures above 200°C. Epoxy resin, as an encapsulation resin, has high mechanical strength, good adhesion, and is less expensive than silicone resin.

[0034] In this invention, a high-entropy multi-element alloy is used as the raw material for the alloy thermistor thin film. The metals include, but are not limited to, two or more metals such as manganese (Mn), cobalt (Co), nickel (Ni), copper (Cu), iron (Fe), (aluminum) Al, and calcium (Ca), and their alloys. Silver (Ag), gold (Au), platinum (Pt), titanium (Ti), tungsten (W), and their alloys are used as electrode materials to form a substrate, an insulating layer, an adhesive layer, an alloy thermistor thin film, an electrode thin film, a first protective layer, and a second protective layer. An alloy thermistor thin film made of the above-mentioned multiple metal materials is sputtered onto the substrate. The alloy thermistor thin film is then annealed to form a multi-element compound film layer with a spinel structure.

[0035] Furthermore, considering the product's requirements for mechanical strength, thermal conductivity, and bending resistance, the substrate material can be any one of Si, Al2O3, AlN, SiC, or flexible materials such as PI. Al2O3, a commonly used substrate in electronic components, possesses good mechanical strength and high electrical insulation. AlN performs similarly to Al2O3 on substrates, but with higher thermal conductivity. SiC boasts a thermal conductivity as high as 300-490 W / (m·K), offering significant advantages in rapid response. Considering the product's use on curved surfaces, flexible material PI can be added as the substrate.

[0036] The insulating layer can be selected from silicon-based compounds, aluminum-based compounds, such as silicon nitride, silicon oxide, or silicon dioxide. Since the product requires the substrate to be an insulator, when using semiconductors such as silicon or silicon carbide or other materials with good conductivity as the substrate, the design of the insulating layer is added.

[0037] To enhance the adhesion between the electrode film and the substrate (such as silicon, silicon dioxide, or dielectric materials) and prevent metal atoms from diffusing into the semiconductor or dielectric layer, thus avoiding device performance degradation, an adhesion layer is needed in the design of this NTC thermistor. Since Ti and Ta exhibit better adhesion to SiO2 or low-k dielectric materials than pure metals, the adhesion layer can be selected from titanium (Ti), tungsten (W), tantalum (Ta), tantalum nitride (TaN), or their intermetallic alloys.

[0038] After annealing, the alloy thermistor film is used to form a metal oxide thermistor film. The metal oxide thermistor film uses a high-entropy multi-element alloy as the raw material for the film layer. The metal types include, but are not limited to, one or more metals and alloys such as manganese, cobalt, nickel, copper, iron, chromium, and aluminum.

[0039] The electrode film can be selected from one or more of silver, gold, platinum, titanium, tungsten and their alloys, as well as any conductive material.

[0040] The first protective layer can be one or more of SiO2 and Si3N4. SiO2 and Si3N4 are excellent passivation protection materials, with excellent resistance to acid and alkali corrosion, oxidation and water vapor, protecting the surface of NTC thermistors from environmental (humidity, ion contamination) and improving product reliability.

[0041] The second protective layer can be selected from one or more of epoxy resin, silicone resin, PI, and other resin materials. Although SiO2 / Si3N4 thin films offer some protection, their thickness is limited due to process constraints. Resin can provide a thicker barrier. Resin possesses flexibility and elasticity, effectively buffering external mechanical stress (such as from drops or vibrations) to reduce mechanical stress on the brittle substrate and prevent brittle fracture of the NTC thermistor or its internal circuitry. Furthermore, resin can tightly encapsulate components, blocking environmental corrosive agents such as moisture, oxygen, and salt spray, especially ensuring protection for the metal leads and solder joints of the NTC thermistor.

[0042] This invention utilizes a Mn-Co-Ni ternary system, a Mn-Co binary system, a Mn-Ni binary system, or a Mn-Co-Ni-Al quaternary system to form an alloy thermistor thin film via sputtering. Electrode patterning and annealing of the alloy thermistor thin film are then performed using laser technology, resulting in crystallization of the alloy thermistor thin film to form a spinel-phase Mn-Co-Ni-O / Mn-Co-O / Mn-Ni-O / Mn-Co-Ni-Al-O ceramic thin film with NTC characteristics. Compared to photolithography, laser technology offers higher efficiency, fewer steps, and no impurity contamination. Under the same process conditions, alloy target sputtering efficiency and utilization are superior to ceramic targets, making it suitable for industrial production. Electrode patterns are often rectangular, interdigitated, or other right-angled straight lines, which can easily lead to pattern accuracy deviations in subsequent processing, reducing product performance precision. Furthermore, straight-line designs result in shorter conduction paths for the same area, leading to poor flexibility in resistance adjustment.

[0043] The Mn-Co-Ni ternary system is Mn 2-2x Co 3x Ni 1-x O (x = 0.2~0.5), the Mn-Co binary system is Mn x Co 3-x O4 (0.8 < x < 2.0), Mn-Ni binary system is Mn x Ni 3-x O4 (0.6 < x < 2.6), or the Mn-Co-Ni-Al quaternary system as Mn x Co y Ni z Al (3-x-y-z) O4(x=0.5~1.1, y=0.8~1.4, z=0.12~0.30).

[0044] The present invention will now be described in detail with reference to specific embodiments.

[0045] Example 1 1) Substrate cleaning: In this example, Si is selected as the substrate material. The Si wafer is placed in a solution of hydrogen peroxide: concentrated sulfuric acid = 1:3 and heated at 245°C for 10 min; b. a solution of hydrogen peroxide: ammonia = 2:1 and heated at 360°C for 10 min; c. a solution of hydrogen peroxide: concentrated hydrochloric acid = 2:1 and heated at 360°C for 10 min. Finally, it is rinsed with deionized water and dried with nitrogen gas for later use.

[0046] 2) Insulating layer: A SiO2 layer with a thickness of about 500 nm is grown on Si using a thermal oxidation method.

[0047] 3) Adhesion layer: Titanium was selected as the adhesion layer. The air in the sputtering furnace chamber was extracted to a pre-vacuum level of 2.5 × 10⁻⁶. -3 Pa, then argon gas is introduced as the working gas, with a power of 80W and a heating temperature of 100℃; a titanium metal layer is sputtered for 10 minutes based on step (2).

[0048] 4) Pre-preparation of alloy thermistor thin films: Mn was prepared by magnetron sputtering. 1.34 Co 0.88 Ni 0.78 The metal target is sputtered onto the substrate obtained in step (3) to obtain the Mn-Co-Ni alloy thin film 140. Sputtering conditions: sputtering power 80W, pre-evacuation degree 2.5×10 -3 Pa, sputtering atmosphere controlled with oxygen-argon volume ratio between 0.1 and 3.0, sputtering temperature 100℃, sputtering time 100min.

[0049] 5) Electrode film preparation: A platinum electrode film was formed on the sample obtained in step (4) by sputtering. The sputtering power was 100W, and the pre-vacuum degree was 2.5×10⁻⁶. -3 Pa, sputtering temperature 100℃; then, an electrode pattern is formed on the electrode thin film by laser etching to expose the alloy thermistor thin film, forming the first electrode thin film and the second electrode thin film. Among them, thin-film NTC thermistors include straight and single-bend types (such as...). Figure 2 ) and waves (such as Figure 3 Thin-film NTC thermistors with three different electrode patterns. The straight, single-bend, and wavy shapes are formed by laser etching on the electrode film.

[0050] 6) Annealing: The sample obtained in step (5) is subjected to thermal annealing in a sintering furnace with an oxygen atmosphere to obtain a Mn-Co-Ni-O alloy thermosensitive film. The annealing temperature is 900℃ and the annealing time is 4h.

[0051] 7) First protective layer: Alumina is selected as the first protective layer. It is formed by sputtering at a power of 80W for 60 minutes to form an aluminum oxide film, which is the first protective layer and completely covers the alloy thermosensitive film prepared in step (6).

[0052] 8) Second protective layer: The second protective layer is formed by screen printing a layer of glass paste on the first protective layer prepared in step (7) to obtain a thin film NTC thermistor.

[0053] Example 2 1) Substrate cleaning: In this example, Si is selected as the substrate material. The Si wafer is placed in a solution of hydrogen peroxide: concentrated sulfuric acid = 1:3 and heated at 245°C for 10 min; b. a solution of hydrogen peroxide: ammonia = 2:1 and heated at 360°C for 10 min; c. a solution of hydrogen peroxide: concentrated hydrochloric acid = 2:1 and heated at 360°C for 10 min. Finally, it is rinsed with deionized water and dried with nitrogen gas for later use.

[0054] 2) Insulating layer: A SiO2 layer with a thickness of about 500 nm is grown on Si using a thermal oxidation method.

[0055] 3) Adhesion layer: Titanium was selected as the adhesion layer. The air in the sputtering furnace chamber was extracted to a pre-vacuum level of 2.5 × 10⁻⁶. -3 Pa, argon gas is introduced as the working gas, power is 80W, heating temperature is 100℃; a titanium metal layer is sputtered for 10min based on step (2).

[0056] 4) Electrode film preparation: A platinum electrode film was formed on the sample obtained in step (3) by sputtering. The sputtering power was 100W, and the pre-vacuum degree was 2.5×10⁻⁶. -3 Pa, sputtering temperature 100℃; then, a wave pattern is etched on the electrode film using laser technology to expose the alloy thermistor film, forming the first electrode film and the second electrode film.

[0057] 5) Pre-preparation of alloy thermistor thin films: Mn was prepared by magnetron sputtering. 1.34 Co 0.88 Ni 0.78 The metal target is sputtered onto the substrate obtained in step (3) to obtain the Mn-Co-Ni alloy thin film 140. Sputtering conditions: sputtering power 80W, pre-evacuation degree 2.5×10 -3 Pa, sputtering control of oxygen-argon volume ratio between 0.1 and 3.0, sputtering temperature 100℃, sputtering time 100min.

[0058] 6) Annealing: The sample obtained in step (5) is subjected to thermal annealing in a sintering furnace with an oxygen atmosphere. The annealing temperature is 900℃ and the annealing time is 4h to obtain a Mn-Co-Ni-O alloy thermosensitive film.

[0059] 7) First protective layer: Alumina is selected as the first protective layer. It is formed by sputtering at a power of 80W for 60 minutes to form an aluminum oxide film, which is the first protective layer and completely covers the alloy thermosensitive film prepared in step (6).

[0060] 8) Second protective layer: The second protective layer is formed by screen printing a layer of glass paste on the first protective layer prepared in step (7) to obtain a thin film NTC thermistor.

[0061] Example 3 To discuss the impact of alloy and oxide ceramic target preparation on product performance, Mn-Co-Ni-O ceramic target was used as the raw material for the thermistor film layer in Example 3 for sputtering.

[0062] 1) Substrate cleaning: In this example, Si is selected as the substrate material. The Si wafer is placed in a solution of hydrogen peroxide: concentrated sulfuric acid = 1:3 and heated at 245°C for 10 min; b. a solution of hydrogen peroxide: ammonia = 2:1 and heated at 360°C for 10 min; c. a solution of hydrogen peroxide: concentrated hydrochloric acid = 2:1 and heated at 360°C for 10 min. Finally, it is rinsed with deionized water and dried with nitrogen gas for later use.

[0063] 2) Insulating layer: A SiO2 layer with a thickness of about 500 nm is grown on Si using a thermal oxidation method.

[0064] 3) Adhesion layer: Titanium was selected as the adhesion layer. The air in the sputtering furnace chamber was extracted to a pre-vacuum level of 2.5 × 10⁻⁶. -3 Pa, then argon gas is introduced as the working gas, with a power of 80W and a heating temperature of 100℃; a titanium metal layer is sputtered for 10 minutes based on step (2).

[0065] 4) Electrode film preparation: A platinum electrode film was formed on the sample obtained in step (3) by sputtering. The sputtering power was 100W, and the pre-vacuum degree was 2.5×10⁻⁶. -3 Pa, sputtering temperature 100℃; then, a wave pattern is etched on the electrode film using laser technology to expose the alloy thermistor film, forming the first electrode film and the second electrode film.

[0066] 5) Preparation of alloy thermistor thin films: Mn 1.34 Co 0.88 Ni 0.78The oxide ceramic target is sputtered onto the substrate obtained in step (3) to obtain the Mn-Co-Ni-O thin film 140. Sputtering conditions: RF sputtering power 100W, pre-evacuation degree 2.5×10 -3 Pa, sputtering control of oxygen-argon volume ratio between 0.1 and 3.0, sputtering temperature 100℃.

[0067] 6) Annealing: The sample obtained in step (5) is subjected to thermal annealing in a sintering furnace with an oxygen atmosphere. The annealing temperature is 900℃ and the annealing time is 4h to obtain a Mn-Co-Ni-O alloy thermosensitive film.

[0068] 7) First protective layer: Alumina is selected as the first protective layer. It is formed by sputtering at a power of 80W for 60 minutes to form an aluminum oxide film, which is the first protective layer and completely covers the alloy thermosensitive film prepared in step (6).

[0069] 8) Second protective layer: The second protective layer is formed by screen printing a layer of glass paste on the first protective layer prepared in step (7) to obtain a thin film NTC thermistor.

[0070] Example 4 1) Substrate cleaning: In this example, Si is selected as the substrate material. The Si wafer is placed in a solution of hydrogen peroxide: concentrated sulfuric acid = 1:3 and heated at 245°C for 10 min; b. a solution of hydrogen peroxide: ammonia = 2:1 and heated at 360°C for 10 min; c. a solution of hydrogen peroxide: concentrated hydrochloric acid = 2:1 and heated at 360°C for 10 min. Finally, it is rinsed with deionized water and dried with nitrogen gas for later use.

[0071] 2) Insulating layer: A SiO2 layer with a thickness of about 500 nm is grown on Si using a thermal oxidation method.

[0072] 3) Adhesion layer: Titanium was selected as the adhesion layer. The air in the sputtering furnace chamber was extracted to a pre-vacuum level of 2.5 × 10⁻⁶. -3 Pa, then argon gas is introduced as the working gas, with a power of 80W and a heating temperature of 100℃; a titanium metal layer is sputtered for 10 minutes based on step (2).

[0073] 4) Pre-preparation of alloy thermistor thin films: Mn was prepared by magnetron sputtering. 1.8 Co 1.2 By sputtering an O4 metal target onto the substrate obtained in step (3), a Mn-Co alloy thin film 140 can be obtained. Sputtering conditions: sputtering power 80W, pre-evacuation degree 2.5×10 -3 Pa, sputtering atmosphere controlled with oxygen-argon volume ratio between 0.1 and 3.0, sputtering temperature 100℃, sputtering time 100min.

[0074] 5) Electrode film preparation: A platinum electrode film was formed on the sample obtained in step (4) by sputtering. The sputtering power was 100W, and the pre-vacuum degree was 2.5×10⁻⁶. -3 Pa, sputtering temperature 100℃; then, a wave pattern is etched on the electrode film using laser technology to expose the alloy thermistor film, forming the first electrode film and the second electrode film.

[0075] 6) Annealing: The sample obtained in step (5) is subjected to thermal annealing in a sintering furnace with an oxygen atmosphere to obtain a Mn-Co-O alloy thermistor film. The annealing temperature is 900℃ and the annealing time is 4h.

[0076] 7) First protective layer: Alumina is selected as the first protective layer. It is formed by sputtering at a power of 80W for 60 minutes to form an aluminum oxide film, which is the first protective layer and completely covers the alloy thermosensitive film prepared in step (6).

[0077] 8) Second protective layer: The second protective layer is formed by screen printing a layer of glass paste on the first protective layer prepared in step (7) to obtain a thin film NTC thermistor.

[0078] Example 5 1) Substrate cleaning: In this example, Si is selected as the substrate material. The Si wafer is placed in a solution of hydrogen peroxide: concentrated sulfuric acid = 1:3 and heated at 245°C for 10 min; b. a solution of hydrogen peroxide: ammonia = 2:1 and heated at 360°C for 10 min; c. a solution of hydrogen peroxide: concentrated hydrochloric acid = 2:1 and heated at 360°C for 10 min. Finally, it is rinsed with deionized water and dried with nitrogen gas for later use.

[0079] 2) Insulating layer: A SiO2 layer with a thickness of about 500 nm is grown on Si using a thermal oxidation method.

[0080] 3) Adhesion layer: Titanium was selected as the adhesion layer. The air in the sputtering furnace chamber was extracted to a pre-vacuum level of 2.5 × 10⁻⁶. -3 Pa, then argon gas is introduced as the working gas, with a power of 100W and a heating temperature of 100℃; a titanium metal layer is sputtered for 10 minutes based on step (2).

[0081] 4) Pre-preparation of alloy thermistor thin films: Mn was prepared by magnetron sputtering. 2.4 Ni 0.6 By sputtering an O4 metal target onto the substrate obtained in step (3), a Mn-Ni alloy thin film 140 can be obtained. Sputtering conditions: sputtering power 80W, pre-evacuation degree 2.5×10 -3Pa, sputtering atmosphere controlled with oxygen-argon volume ratio between 0.1 and 3.0, sputtering temperature 100℃, sputtering time 100min.

[0082] 5) Electrode film preparation: A platinum electrode film was formed on the sample obtained in step (4) by sputtering. The sputtering power was 100W, and the pre-vacuum degree was 2.5×10⁻⁶. -3 Pa, sputtering temperature 100℃; then, a wave pattern is etched on the electrode film using laser technology to expose the alloy thermistor film, forming the first electrode film and the second electrode film.

[0083] 6) Annealing: The sample obtained in step (5) is subjected to thermal annealing in a sintering furnace with an oxygen atmosphere to obtain a Mn-Ni-O alloy thermistor film. The annealing temperature is 900℃ and the annealing time is 4h.

[0084] 7) First protective layer: Alumina is selected as the first protective layer. It is formed by sputtering at a power of 80W for 60 minutes to form an aluminum oxide film, which is the first protective layer and completely covers the alloy thermosensitive film prepared in step (6).

[0085] 8) Second protective layer: The second protective layer is formed by screen printing a layer of glass paste on the first protective layer prepared in step (7) to obtain a thin film NTC thermistor.

[0086] Example 6 1) Substrate cleaning: In this example, Si is selected as the substrate material. The Si wafer is placed in a solution of hydrogen peroxide: concentrated sulfuric acid = 1:3 and heated at 245°C for 10 min; b. a solution of hydrogen peroxide: ammonia = 2:1 and heated at 360°C for 10 min; c. a solution of hydrogen peroxide: concentrated hydrochloric acid = 2:1 and heated at 360°C for 10 min. Finally, it is rinsed with deionized water and dried with nitrogen gas for later use.

[0087] 2) Insulating layer: A SiO2 layer with a thickness of about 500 nm is grown on Si using a thermal oxidation method.

[0088] 3) Adhesion layer: Titanium was selected as the adhesion layer. The air in the sputtering furnace chamber was extracted to a pre-vacuum level of 2.5 × 10⁻⁶. -3 Pa, then argon gas is introduced as the working gas, with a power of 80W and a heating temperature of 100℃; a titanium metal layer is sputtered for 10 minutes based on step (2).

[0089] 4) Pre-preparation of alloy thermistor thin films: Mn was prepared by magnetron sputtering. 0.8 Co 1.1 Ni 0.24 Al 0.86By sputtering an O4 metal target onto the substrate obtained in step (3), a Mn-Co-Ni-Al alloy thin film 140 can be obtained. Sputtering conditions: sputtering power 80W, pre-evacuation degree 2.5×10 -3 Pa, sputtering atmosphere controlled with oxygen-argon volume ratio between 0.1 and 3.0, sputtering temperature 100℃, sputtering time 100min.

[0090] 5) Electrode film preparation: A platinum electrode film was formed on the sample obtained in step (4) by sputtering. The sputtering power was 100W, and the pre-vacuum degree was 2.5×10⁻⁶. -3 Pa, sputtering temperature 100℃; then, a wave pattern is etched on the electrode film using laser technology to expose the alloy thermistor film, forming the first electrode film and the second electrode film.

[0091] 6) Annealing: The sample obtained in step (5) is subjected to thermal annealing in a sintering furnace with an oxygen atmosphere to obtain a Mn-Co-Ni-Al-O alloy thermosensitive film. The annealing temperature is 1000℃ and the annealing time is 4h.

[0092] 7) First protective layer: Alumina is selected as the first protective layer. It is formed by sputtering at a power of 80W for 60 minutes to form an aluminum oxide film, which is the first protective layer and completely covers the alloy thermosensitive film prepared in step (6).

[0093] 8) Second protective layer: The second protective layer is formed by screen printing a layer of glass paste on the first protective layer prepared in step (7) to obtain a thin film NTC thermistor.

[0094] The electrical performance of the NTC thermistors obtained in Examples 1, 2, and 3 was tested. The alloy thermistor thin film material prepared in Example 1 was characterized by XRD, subjected to resistance-temperature relationship testing, and subjected to long-term high-temperature reliability testing. Long-term reliability testing was performed on Examples 4, 5, and 6. The results are as follows: Figure 6-19 As shown.

[0095] This application relates to R 25 B 25 / 50 R is a performance characterization parameter of the NTC. 25 This is the resistance value of NTC at 25℃. The B value is the material constant of NTC, indicating the sensitivity of NTC to temperature. It is usually expressed as B. 25 / 50 The measurement is calculated using the following formula: B T1 / T2 =ln(R T1 / R T2 ) / (1 / (T1+273.15)-1 / (T2+273.15)) Among them, R T1 RT2 These are the NTC resistance values ​​corresponding to temperatures T1 and T2.

[0096] Figure 6 The resistance-temperature characteristic curve of the NTC thermistor shows that the prepared sample has electrical properties and conforms to the characteristics of NTC. To verify the NTC characteristics of the thermistor film material, XRD peak characterization of the alloy thermistor film was further performed. Figure 7 According to the comparison with the material standard card, the alloy thermistor film showed peaks of MnCo2O4, NiMn2O4 and CoMn2O4 after annealing, which are spinel phases, consistent with the crystal phase obtained in the target, indicating good crystallinity of the film layer.

[0097] Figure 8 , Figure 9 This refers to the effect of different types of target materials and electrode structures on the electrical performance parameters (R) of NTC thermistors. 25 B 25 / 50 Analysis shows that the NTC thermistor in R... 25 and B 25 / 50 The results show that sputtering with metal targets is more concentrated, and the products prepared with top electrode structures have more concentrated performance, indicating more stable performance.

[0098] Figure 10 , 11 This reflects the different shapes of the NTC thermistor R 25 The effect of the value can be seen intuitively; the design of the NTC thermistor R with a curved arc is evident. 25 The R value is less than that of a straight line design, which is determined by the formula R=ρl / S. This further proves that products with wavy or single-bend designs have a negative impact on the R value of NTC thermistors. 25 The adjustable space is more flexible and the application range is wider; in addition, the electrode pattern with single bend and wave is also better in terms of performance consistency, which is conducive to the control of yield in the production process.

[0099] Figure 12-19 This data represents long-term high-temperature storage of NTCs from different systems. NTCs operate at high temperatures for extended periods, during which ion diffusion and slow changes in their microstructure occur within the material, leading to variations in the NTC's resistance and material parameters (B). 25 / 50 The data shows a certain degree of drift, so it is a simulation of the actual working scenario to obtain the range of performance changes.

[0100] Figure 12 , 13 The Mn-Co-Ni-O system NTC thermistor R at 200℃ 25 B 25 / 50 The rate of change over storage time.

[0101] Figure 14 , 15 The Mn-Co system NTC thermistor R at 200℃ 25 B 25 / 50 The rate of change over storage time.

[0102] Figure 16 , 17 The R of the Mn-Ni system NTC thermistor at 200℃ 25 B 25 / 50 The rate of change over storage time.

[0103] Figure 18 , 19 The Mn-Co-Ni-Al system NTC thermistor R at 200℃ 25 B 25 / 50 The rate of change over storage time.

[0104] Based on the above data, it can be concluded that a top electrode structure is adopted ( Figure 5 The alloy thermistor film prepared by the method of preparing oxide thermistor films by post-annealing of alloy targets has good crystallinity, controllable electrical performance parameters, and high reliability (Mn-Co-Ni system NTC after aging at 200℃ for 1000H, product B) 25 / 50 Rate of change < 1%, R 25 The rate of change is 1.9%; the B of NTC in the Mn-Co system 25 / 50 Rate of change < 1%, R 25 The rate of change is 2.48%. The B of the Mn-Ni system products... 25 / 50 Rate of change < 1%, R 25 The rate of change is approximately 2.0%. The B-value of the Mn-Co-Ni-Al quaternary system products... 25 / 50 Rate of change < 1%, R 25 The rate of change is approximately 1.57%.

[0105] It should be understood that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Those skilled in the art can modify the technical solutions described in the above embodiments, or make equivalent substitutions for some of the technical features; and all such modifications and substitutions should fall within the protection scope of the appended claims of this utility model.

Claims

1. A thin-film NTC thermistor, characterized in that, The material comprises a substrate, an insulating layer, an adhesive layer, an alloy thermistor film, an electrode film, a first protective layer, and a second protective layer, which are stacked sequentially. The electrode film does not cover the alloy thermistor film at the electrode pattern, and the electrode pattern divides the electrode film into a first electrode film and a second electrode film. On both sides of the electrode pattern, the first electrode film and the second electrode film respectively cover the alloy thermistor film and the adhesive layer.

2. The NTC thermistor according to claim 1, characterized in that, The electrode pattern is a bent shape.

3. The NTC thermistor according to claim 1, characterized in that, The electrode pattern is arc-shaped.

4. The NTC thermistor according to claim 1, characterized in that, The insulating layer is a silicon oxide layer or a silicon nitride film layer.

5. The NTC thermistor according to claim 4, characterized in that, The thickness of the insulating layer is 10-1000 nm.

6. The NTC thermistor according to claim 5, characterized in that, The thickness of the insulating layer is 500 nm.

7. The NTC thermistor according to claim 3, characterized in that, The arc shape is a single-bend arc shape.

8. The NTC thermistor according to claim 3, characterized in that, The arc shape is a wave shape.

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