A negative temperature coefficient thermistor temperature sensor, its manufacturing method and application

Abstract

The application discloses a negative temperature coefficient thermistor temperature sensor and a manufacturing method and application thereof, and belongs to the detection field. The thermistor temperature sensor comprises a monocrystalline silicon substrate block and a negative temperature coefficient thermistor film grown on a silicon dioxide layer of the monocrystalline silicon substrate block. The negative temperature coefficient thermistor film is an Mn-Co-Ni-Cu-O thermistor film, and has a spinel structure. The application introduces Cu elements, performs 1 / 3 thickness pre-cutting on the monocrystalline silicon substrate, and adopts twice magnetron sputtering processes, so that the brittleness and plasticity of the thermistor film are optimized, the in-plane residual stress of the thermistor film is reduced, the Mn-Co-Ni-Cu-O thermistor film with a thickness of more than 7 microns is prepared, the thermistor film surface is intact and is well combined with the silicon dioxide layer, and cracking and falling off do not occur; the resistance of the thermistor film is less than 500 ohms, and annealing heat treatment is not needed; and the technical route of the application is simple and efficient, and the production efficiency and the yield are very high.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of detection, in particular to a negative temperature coefficient thermistor temperature sensor and a manufacturing method and application thereof. BACKGROUND

[0002] The negative temperature coefficient (NTC) thermistor temperature sensor has the advantages of high temperature measurement accuracy, high sensitivity, good stability, low price, long service life, etc., and has a wide and important application in the fields of aerospace, marine environment and household appliances. However, with the increasingly small integrated circuit process, the increasingly high degree of integration of wafer multi-parameter and multi-module, the NTC thermistor is required to have smaller size, higher measurement accuracy and smaller uncertainty.

[0003] At present, there are many kinds of block, sheet, spherical thermistor temperature sensors on the market, but they have the problems of large volume, complex manufacturing process, large performance difference between product batches, and the measurement accuracy and accuracy need to be further improved, etc., which cannot meet the requirements of integrated circuits, advanced manufacturing, micro-nano processing and other fields for smaller size, higher measurement accuracy and smaller measurement uncertainty of temperature sensors.

[0004] Compared with block, sheet and spherical thermistor temperature sensors, the negative temperature coefficient thermistor film is most likely to meet the application requirements of integrated circuits, advanced manufacturing and micro-nano devices. At present, some research teams have successfully prepared negative temperature coefficient thermistor films by magnetron sputtering method, molecular beam epitaxy method, pump laser deposition method or chemical solution deposition method. Among them, the magnetron sputtering method is the main method at present, and the technical route is: first, a thermistor film is prepared by magnetron sputtering on a single crystal silicon wafer with a silicon dioxide layer. The thickness of the prepared thermistor film is usually several tens to several hundred nanometers. Because the brittle thermistor film is grown on a (4-8) inch single crystal silicon wafer, the thickness of the film generally cannot exceed 1 μm. If the thickness of the brittle thermistor film exceeds 1 μm, the in-plane residual stress will be too large, which will cause the film to crack or fall off from the substrate.

[0005] However, if the thickness of the thermistor film is too small (several tens to several hundred nanometers), its resistance will be very large, usually (100-1000) kΩ. The temperature measurement accuracy and resolution of the thermistor film will be poor due to the large resistance. Therefore, in order to reduce the resistance of the thermistor film, the prepared thermistor film must be subjected to multiple annealing heat treatments. The annealing heat treatment can reduce the resistance of the thermistor film and release the in-plane residual stress of the thermistor film. After the annealing heat treatment, electrodes are prepared on the surface of the thermistor film by evaporation plating or other technologies. After the electrodes are prepared, the wafer is cut to full thickness using a laser cutting machine to obtain separated single thermistor devices. Because there are many thermistor devices on the large wafer, the wafer must be cut and separated before it can be actually used.

[0006] Existing magnetron sputtering techniques for fabricating thermistor thin films suffer from several problems: 1) The fabricated thermistor thin films require multiple annealing heat treatments to reduce resistance and in-plane residual stress, resulting in a lengthy and complex process; 2) Thermistor thin films are prone to oxidation during multiple annealing heat treatments, altering their chemical composition; 3) Using evaporation deposition or other techniques to fabricate electrodes increases the complexity and operability of the process, and the electrodes fabricated using these techniques are prone to breakage and failure; 4) Finally, the dicing and separation of the thermistor devices on the wafer can easily contaminate and damage the devices, reducing yield. These problems hinder the development and application of negative temperature coefficient thermistor thin film temperature sensors in fields such as integrated circuits. Summary of the Invention

[0007] Invention objectives

[0008] To overcome the above shortcomings, the purpose of this invention is to provide a simple, efficient, and highly productive negative temperature coefficient thermistor temperature sensor with a high yield and production efficiency, as well as its manufacturing method and application.

[0009] Solution

[0010] To achieve the objectives of this invention, the technical solution adopted is as follows:

[0011] In a first aspect, the present invention provides a negative temperature coefficient thermistor temperature sensor, comprising a single-crystal silicon substrate and a negative temperature coefficient thermistor thin film grown on a silicon dioxide layer of the single-crystal silicon substrate, wherein the negative temperature coefficient thermistor thin film is a Mn-Co-Ni-Cu-O thermistor thin film having a spinel structure; wherein the mass ratio of Mn, Co, Ni, Cu and O in the negative temperature coefficient thermistor thin film is (28-32):(28-32):(14-16):(0.1-2.5):(20-28).

[0012] Furthermore, platinum wires are adhered to both sides of the negative temperature coefficient thermistor film, optionally using silver adhesive for bonding.

[0013] Furthermore, the thickness of the negative temperature coefficient thermistor film is ≥7μm, optionally ≥7.5μm, or optionally ≥7.7μm.

[0014] Furthermore, the resistance of the negative temperature coefficient thermistor film is less than 700Ω, and optionally less than 500Ω.

[0015] Furthermore, the size of the negative temperature coefficient thermistor film is (2~10)mm×(2~10)mm, and optionally 5mm×5mm.

[0016] Furthermore, the negative temperature coefficient thermistor film is deposited multiple times using a Mn-Co-Ni-Cu-O alloy target through a physical deposition method; optionally, the physical deposition method includes magnetron sputtering, laser molecular beam epitaxy, or electron beam evaporation; optionally, the deposition is performed at least twice.

[0017] Furthermore, in the negative temperature coefficient thermistor film, the mass ratio of Mn, Co, Ni, Cu, and O is (28-30):(28-30):(15-15.5):(0.5-2):(23-28), and optionally 30:30:(15-15.5):(0.5-2):(23-24).

[0018] Furthermore, the spinel unit cell has the structure AB2O4, where A ions occupy oxygen tetrahedral voids composed of four oxygen atoms, and B ions occupy oxygen octahedral voids composed of six oxygen atoms.

[0019] In a second aspect, a single-crystal silicon substrate is provided for fabricating the negative temperature coefficient thermistor temperature sensor described in the first aspect. The single-crystal silicon substrate has longitudinally and transversely interwoven grooves cut into it to form several small units, which are used to divide the substrate into several single-crystal silicon substrate blocks along the grooves.

[0020] Further, the groove depth on the monocrystalline silicon substrate is 160μm to 320μm; optionally, the groove depth is 1 / 4 to 1 / 2 of the thickness of the monocrystalline silicon substrate, and optionally 1 / 3.

[0021] Furthermore, the plurality of small units are plurality of square units, and optionally the size of the square unit is (2-10)mm×(2-10)mm, or optionally 5mm×5mm.

[0022] Thirdly, a method for manufacturing a negative temperature coefficient thermistor thin film is provided, comprising the following steps:

[0023] 1) Pre-treat the Mn-Co-Ni-Cu-O alloy target to remove the surface oxide layer and contaminants;

[0024] 2) Pre-treat the monocrystalline silicon substrate described in the second aspect to remove surface impurities and contaminants;

[0025] 3) Using the Mn-Co-Ni-Cu-O alloy target material pretreated in step 1), physical deposition is performed on the single-crystal silicon substrate pretreated in step 2, with at least two depositions, to obtain a negative temperature coefficient thermistor film.

[0026] Further, in step 3), the physical deposition method includes: at the beginning of the deposition, a first sputtering deposition is performed in an inert atmosphere, followed by cooling, a second sputtering deposition is performed, followed by cooling; and so on, to obtain a negative temperature coefficient thermistor film through at least two sputtering depositions.

[0027] Furthermore, the time for the first sputtering coating is (150-250) min, optionally 200 min.

[0028] Furthermore, the second sputtering coating time is (250-350) min, optionally 300 min.

[0029] Furthermore, the power of sputtering coating is (200~260)W, optionally 240W.

[0030] Furthermore, the inert atmosphere is argon or helium.

[0031] Furthermore, the flow rate of the inert atmosphere is (48–52) sccm, optionally 50 sccm.

[0032] Furthermore, the sputtering vacuum degree is (10 -7 ~10 -8 Torr, optionally 10 -7 Torr.

[0033] Furthermore, in step 3), before starting the coating process, the Mn-Co-Ni-Cu-O alloy target is pre-sputtered to remove contaminants and impurities from the target surface.

[0034] Furthermore, it also includes a segmentation step: segmenting the negative temperature coefficient thermistor film obtained in step 3), optionally segmenting along the corresponding groove of the single-crystal silicon substrate.

[0035] Fourthly, a method for manufacturing a negative temperature coefficient thermistor temperature sensor as described in the first aspect is provided, wherein liquid silver paste is added to both sides of a negative temperature coefficient thermistor film of suitable size prepared by the manufacturing method described in the third aspect, a platinum wire electrode is inserted into the liquid silver paste, and the mixture is stabilized, cured, and dried to obtain a negative temperature coefficient thermistor temperature sensor.

[0036] Fifthly, the application of the negative temperature coefficient thermistor temperature sensor described in the first aspect, the single-crystal silicon substrate described in the second aspect, the negative temperature coefficient thermistor thin film prepared by the manufacturing method described in the third aspect, and the negative temperature coefficient thermistor temperature sensor prepared by the manufacturing method described in the fourth aspect in integrated circuits, advanced manufacturing, and micro / nano fabrication.

[0037] Beneficial effects

[0038] This invention optimizes the brittleness and plasticity of the thermistor film by introducing Cu element, pre-cutting the film to 1 / 3 thickness on a single-crystal silicon substrate, and employing a two-stage magnetron sputtering process. This reduces the in-plane residual stress of the thermistor film, resulting in a Mn-Co-Ni-Cu-O thermistor film with a thickness exceeding 7.7 μm. The surface of the thermistor film remains intact and is well bonded to the silicon dioxide layer without cracking or peeling. The resistivity of the prepared thermistor film is less than 500 Ω, eliminating the need for annealing heat treatment. Compared to existing technologies, this application's approach is simple, efficient, and boasts very high production efficiency and yield. Attached Figure Description

[0039] One or more embodiments are illustrated by way of example with reference to the accompanying drawings, and these illustrative examples are not intended to limit the embodiments. The term "illustrative" as used herein means "serving as an example, embodiment, or illustration." Any embodiment illustrated herein as "illustrative" is not necessarily to be construed as superior to or better than other embodiments.

[0040] Figure 1 This is a diagram of an embodiment of the negative temperature coefficient thermistor temperature sensor prepared according to the present invention.

[0041] Figure 2 The images and structural diagrams show a monocrystalline silicon substrate pre-cut to 1 / 3 thickness according to the present invention; where A is a photograph of the actual object; B is a top view of the monocrystalline silicon substrate; and C is a partial cross-sectional view.

[0042] Figure 3 This is a photograph of the negative temperature coefficient thermistor temperature sensor prepared according to the present invention.

[0043] Figure 4 This is a SEM image of the Mn-Co-Ni-Cu-O thermistor film prepared in Example 1 of the present invention.

[0044] Figure 5 The image shows the AFM pattern of the Mn-Co-Ni-Cu-O thermistor thin film prepared in Example 1 of the present invention.

[0045] Figure 6 This is a TEM image of the Mn-Co-Ni-Cu-O thermistor thin film prepared in Example 1 of the present invention.

[0046] Figure 7 The macroscopic morphology of the Mn-Co-Ni-Cu-O thermistor film prepared in Comparative Example 1 of the present invention is shown.

[0047] Figure 8The temperature-resistance relationship diagram is shown for the negative temperature coefficient thermistor temperature sensor prepared in Embodiment 1 of the present invention; wherein devices 1 and 2 are two randomly selected from the prepared devices, and the solid lines corresponding to devices 1 and 2 are their actual temperature-resistance measurement data; the fitting lines of devices 1 and 2 respectively represent the fitting lines of the actual temperature-resistance measurement data of devices 1 and 2. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0049] Furthermore, to better illustrate the present invention, numerous specific details are provided in the following detailed embodiments. Those skilled in the art should understand that the present invention can be practiced without certain specific details. In some embodiments, materials, elements, methods, and means well known to those skilled in the art are not described in detail in order to highlight the spirit of the invention.

[0050] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprises" shall be understood to include the stated elements or components without excluding other elements or other components.

[0051] This invention provides a negative temperature coefficient thermistor thin film, comprising a platinum wire electrode, a Mn-Co-Ni-Cu-O thermistor thin film, insulating silicon dioxide, and a single-crystal silicon substrate. The Mn-Co-Ni-Cu-O thermistor thin film has a spinel structure, which can be viewed as a cubic close-packed structure formed by oxygen ions. Its unit cell structure is AB₂O₄, where A ions occupy oxygen tetrahedral vacancies composed of four oxygen atoms, and B ions occupy oxygen octahedral vacancies composed of six oxygen atoms. The thermistor properties of the spinel-structured thermistor material largely depend on the jumping conductivity between variable-valence cations located in the oxygen octahedra within the crystal structure. In the oxygen octahedral structure of the Mn-Co-Ni-Cu-O thermistor thin film, some oxygen ions detach to obtain a certain concentration of oxygen vacancies. These oxygen vacancies not only provide additional electrons but also lead to deviations in the material's stoichiometry, changes in the valence state of metal cations, and oxygen octahedral distortion, effectively improving and regulating the material's physical properties and enhancing the thermistor performance of the thin film. Experiments show that the negative temperature coefficient thermistor film described in this invention has a resistance of less than 500Ω, exhibiting excellent thermistor performance and temperature measurement accuracy, ensuring the effectiveness of the thermistor sensor, and facilitating the application of negative temperature coefficient thermistor films in the field of integrated circuits.

[0052] In a first aspect, the present invention provides an embodiment of a negative temperature coefficient thermistor temperature sensor, such as... Figure 1 As shown, it includes a single-crystal silicon substrate 1' and a negative temperature coefficient thermistor 3 grown on a silicon dioxide layer 10 on the single-crystal silicon substrate 1'. The negative temperature coefficient thermistor 3 is a Mn-Co-Ni-Cu-O thermistor with a spinel structure.

[0053] The single-crystal silicon substrate 1' refers to a small block formed by dividing a single-crystal silicon substrate. In use, silver paste is used to attach 80μm diameter platinum wires to both sides of the negative temperature coefficient thermistor film to form electrodes.

[0054] Furthermore, the thickness of the negative temperature coefficient thermistor film 3 is ≥7μm, optionally ≥7.5μm, optionally ≥7.7μm. Its resistance is less than 700Ω, optionally less than 500Ω.

[0055] Furthermore, the negative temperature coefficient thermistor film 3 has a size of (2-10) mm × (2-10) mm, and optionally 5 mm × 5 mm.

[0056] Furthermore, the negative temperature coefficient thermistor film 3 is deposited multiple times using a Mn-Co-Ni-Cu-O alloy target through a physical deposition method; optionally, the physical deposition method includes magnetron sputtering, laser molecular beam epitaxy, or electron beam evaporation; optionally, the deposition is performed at least twice.

[0057] Furthermore, in the negative temperature coefficient thermistor film 3, the mass ratio of Mn, Co, Ni, Cu, and O is (28-32):(28-32):(14-16):(0.1-2.5):(20-28), optionally (28-30):(28-30):(15-15.5):(0.5-2):(23-28), optionally 30:30:(15-15.5):(0.5-2):(23-24).

[0058] Furthermore, the spinel unit cell has the structure AB2O4, where A ions occupy oxygen tetrahedral voids composed of four oxygen atoms, and B ions occupy oxygen octahedral voids composed of six oxygen atoms.

[0059] Secondly, the present invention provides an embodiment of a single-crystal silicon substrate 1 for fabricating the negative temperature coefficient thermistor temperature sensor described in the first aspect, such as... Figure 2 As shown, longitudinal and transverse grooves 2 are cut on the monocrystalline silicon substrate 1 to form several small units (one small unit corresponds to one monocrystalline silicon substrate block 1'), which are used to divide the substrate into several monocrystalline silicon substrate blocks 1' along the grooves 2.

[0060] Furthermore, the depth of the groove 2 on the monocrystalline silicon substrate 1 is 160μm to 320μm; optionally, the depth of the groove 2 is 1 / 4 to 1 / 2 of the thickness of the monocrystalline silicon substrate, and optionally 1 / 3;

[0061] Furthermore, the small units are several square units, and the size of the square units can be (2~10)mm×(2~10)mm, or 5mm×5mm.

[0062] Furthermore, the present invention provides a preferred preparation method, as follows:

[0063] Example 1

[0064] The manufacturing method of the negative temperature coefficient thermistor temperature sensor in this embodiment is carried out according to the following steps:

[0065] 1) Pretreatment of Mn-Co-Ni-Cu-O alloy target: Mn, Co, Ni, Cu and O elements were prepared in a mass fraction ratio of 30:30:15.5:0.5:24 to form Mn-Co-Ni-Cu-O alloy target. The surface of the Mn-Co-Ni-Cu-O alloy target was polished with 300 mesh, 600 mesh, 1200 mesh and 1800 mesh silicon carbide sandpaper in sequence. After polishing, the target was cleaned and dried to remove the surface oxide layer, and the pretreated Mn-Co-Ni-Cu-O alloy target was obtained.

[0066] 2) 1 / 3 Thickness Cutting of Monocrystalline Silicon Substrate: A silicon wafer laser dicing machine is used to cut the monocrystalline silicon substrate with a silicon dioxide layer to 1 / 3 thickness. Longitudinal and transverse cuts are made from the surface of the silicon dioxide layer, creating multiple 5mm × 5mm square pieces interwoven within the substrate. However, the overall structure remains a complete monocrystalline silicon wafer. (See...) Figure 2 The pre-cutting of the single-crystal silicon substrate to 1 / 3 thickness in this step can optimize the technical route for preparing thermistor thin films by magnetron sputtering, and improve production efficiency and yield.

[0067] 3) Pretreatment of monocrystalline silicon substrate: The cut monocrystalline silicon substrate is immersed in acetone, anhydrous ethanol, deionized water and anhydrous ethanol in sequence for ultrasonic cleaning twice, each time for 5 minutes. The monocrystalline silicon substrate is then removed and the surface of the monocrystalline silicon substrate is dried with high-purity nitrogen gas to obtain the pretreated monocrystalline silicon substrate.

[0068] 4) Pre-sputtering of Mn-Co-Ni-Cu-O alloy target: Install the pretreated Mn-Co-Ni-Cu-O alloy target from step 1) onto the target position at the bottom of the DC magnetron sputtering chamber. Install the pretreated single-crystal silicon substrate from step 3) onto the substrate stage at the top of the DC magnetron sputtering chamber. Close the magnetron sputtering chamber and turn on the vacuum system to evacuate. When the mechanical pump evacuates the chamber vacuum to less than 10...-2 After Torr, turn on the molecular pump and turn off the mechanical pump, evacuating the chamber to a vacuum level of less than 10. -7 After Torr, the Ar gas flow rate was set to 50 sccm, the sputtering power of the alloy target was set to 240 W, and the baffle above the target was extended to block the Mn-Co-Ni-Cu-O alloy target, so that the Mn-Co-Ni-Cu-O alloy target was pre-sputtered for 30 minutes to remove contaminants and impurities from the surface of the alloy target.

[0069] 5) Preparation of Mn-Co-Ni-Cu-O thermistor film: After pre-sputtering the alloy target for 30 min, the baffle above the alloy target was removed, and film deposition on the single crystal silicon substrate was started; the Ar gas flow rate was maintained at 50 sccm, the power was maintained at 240 W, and after sputtering for 200 min, the voltage and current were turned off, and the entire magnetron sputtering system was allowed to cool for 60 min. Then the voltage and current were restored, and sputtering continued for 300 min. After the sputtering was completed, the voltage and current were turned off, and after cooling for 40 min, the cavity was opened, and the prepared Mn-Co-Ni-Cu-O thermistor film was taken out.

[0070] After two magnetron sputtering processes (200 min + 300 min), the film resistance was measured to be (0-3) kΩ using a multimeter. Previous experiments by the inventors revealed that after a single magnetron sputtering (200 min), the resistance was (20-60) kΩ. Higher resistance leads to lower temperature measurement accuracy and resolution of the thermistor film, and may even result in the absence of negative temperature characteristics. This invention increases the thickness of the thermistor film through multiple sputtering processes, thereby reducing its resistance. The use of a grooved monocrystalline silicon substrate reduces in-plane residual stress in the thermistor film, preventing cracking and detachment, thus improving the temperature measurement accuracy and precision of the thermistor film device. This solves the problem in existing technologies where increasing film thickness fails to release accumulated stress, leading to cracking and detachment.

[0071] 6) Break the Mn-Co-Ni-Cu-O thermistor film along with the monocrystalline silicon substrate into 5mm×5mm pieces along the groove (due to the longitudinal and transverse grooves on the monocrystalline silicon substrate, most of the sputtered material enters the bottom of the groove during sputtering, and a small part adheres to the 5mm×5mm pieces. Because of the presence of the grooves, the monocrystalline silicon substrate is also easy to break along the bottom of the groove, that is, the connection between the 5mm×5mm pieces is weak and easy to break).

[0072] 7) Then, drop liquid silver paste onto both ends of each thermistor film piece. Using tweezers, quickly insert one end of a 1.5cm long, 80μm diameter platinum wire into the silver paste droplet and hold it still for 20-30 seconds. After the silver paste has cured, release the tweezers and continue to drop 1-2 drops of silver paste onto the platinum wire bonding end. Place the entire thermistor device in a well-ventilated and dry place to dry for 4-5 hours. See the attached photo for details. Figure 3As shown.

[0073] Example 2

[0074] The difference from Example 1 is that the alloy target is prepared in a different ratio. Specifically, Mn, Co, Ni, Cu and O elements are prepared in a mass fraction ratio of 30:30:15:2:23 to prepare Mn-Co-Ni-Cu-O alloy target. The remaining steps are the same as in Example 1.

[0075] Example 3

[0076] The difference from Example 1 is that the alloy target is prepared in a different ratio. Specifically, Mn, Co, Ni, Cu and O elements are prepared in a mass fraction ratio of 28:28:15.5:0.5:28 to prepare Mn-Co-Ni-Cu-O alloy target. The remaining steps are the same as in Example 1.

[0077] Example 4

[0078] Splash count

[0079] The difference from Example 1 is that the number of sputtering operations is different; specifically, only one sputtering deposition is performed, while the remaining steps are the same as in Example 1.

[0080] In the above embodiments, the Mn-Co-Ni-Cu-O thermistor film can also be prepared by other physical deposition methods such as laser molecular beam epitaxy and electron beam evaporation.

[0081] Comparative Example 1

[0082] The difference from Example 1 is that step 2) is not performed on the single-crystal silicon substrate, and the Mn-Co-Ni-Cu-O thin film is cut in step 6). Steps 1), 3), 4), and 5) are the same as in Example 1.

[0083] Comparative Example 2

[0084] The difference from Comparative Example 1 is that in step 5), annealing is performed. The film sample is placed in an annealing furnace, the annealing oxidation treatment temperature is 700℃, and the annealing time is 120 minutes to obtain the annealed thermistor film.

[0085] Comparative Example 3

[0086] The difference from Comparative Example 1 is that step 5) is sputtered only once: after the alloy target is pre-sputtered for 30 minutes, the baffle above the alloy target is removed and the coating on the single crystal silicon begins; the Ar gas flow rate is maintained at 50 sccm and the power is maintained at 240 W. After sputtering for 200 minutes, the voltage and current are turned off, and after cooling for 40 minutes, the cavity is opened and the prepared Mn-Co-Ni-Cu-O thermistor film is taken out.

[0087] Test Example 1

[0088] The thickness of each embodiment and comparative example was measured, and the morphology of the thermal film was observed.

[0089] Testing revealed that the thicknesses of the Mn-Co-Ni-Cu-O thermistor films in Examples 1, 2, 3, and 4 were 7.7 μm, 7.6 μm, 7.7 μm, and 2.9 μm, respectively. The film surfaces were all intact and well-bonded to the silicon dioxide layer on the single-crystal silicon substrate, without cracking or detachment. In contrast, the thicknesses of the Mn-Co-Ni-Cu-O thermistor films in Comparative Examples 1 and 2 were 7.7 μm and 7.8 μm, respectively. Although these thicknesses exceeded 7.7 μm, cracking and detachment occurred on the film surfaces. Figure 7 As shown in Comparative Example 3, after reducing the number of sputtering cycles, the thickness of the thermistor film is 2.9 μm, but it is prone to contamination and damage when slicing the single-crystal silicon substrate.

[0090] Test Example 2

[0091] The resistance of the various embodiments and comparative examples was measured using an unbalanced bridge method. This method involves the working principle and process of the bridge, including pre-balancing the bridge and measuring the relationship between the resistance of the alloy material and temperature at different temperatures. The unbalanced bridge has high sensitivity and is suitable for measuring the temperature coefficient of resistance of alloy materials. When the preset temperature is stable, the output voltage of the unbalanced bridge and the resistance value of the thermistor measured by a digital multimeter are recorded simultaneously. This process is then repeated at different temperatures to obtain a sufficient number of measurement points. The measured resistances of the Mn-Co-Ni-Cu-O thermistor films in Examples 1, 2, 3, and 4 are 420Ω, 390Ω, 670Ω, and 1825Ω, respectively. The resistances of Comparative Examples 1, 2, and 3 are 430Ω, 370Ω, and 1925Ω, respectively.

[0092] The results of Test Examples 1 and 2 show that the Mn-Co-Ni-Cu-O thermistor films prepared in Examples 1, 2, and 3 have low resistance and are not prone to cracking or detachment. The thermistor films prepared in Example 4 and Comparative Example 3 have high resistance. The thermistor film of Example 4 is not prone to cracking or detachment, while the thermistor film of Comparative Example 3 is prone to cracking and detachment, resulting in low production efficiency. Although the Mn-Co-Ni-Cu-O thermistor films prepared in Comparative Examples 1 and 2 also have low resistance, they are prone to cracking and detachment, leading to low production efficiency.

[0093] Test Example 3

[0094] The Mn-Co-Ni-Cu-O thermistor films of Examples 1-4 were imaged using scanning electron microscopy (SEM), atomic force microscopy (AFM), and transmission electron microscopy (TEM), respectively. The SEM, AFM, and TEM images of Example 1 are shown below. Figure 4 , 5 As shown in Figures 6, the results show that the surface of the thermosensitive film is very smooth with a roughness of (15-20) nm and a film thickness of 7.7 μm. The thermosensitive film is composed of columnar crystals, grows densely, and the crystal structure is mainly spinel structure.

[0095] Test Example 4

[0096] The relationship between resistance and temperature was measured using the unbalanced bridge method, and the resistance-temperature curve was plotted. The results are as follows: Figure 8 The results show that the thermistor has a very significant resistance-temperature linear relationship and exhibits a negative temperature coefficient.

[0097] This invention optimizes the brittleness and plasticity of the thermistor film by introducing Cu element, pre-cutting the film to 1 / 3 thickness on a single-crystal silicon substrate, and employing a two-stage magnetron sputtering process. This reduces the in-plane residual stress of the thermistor film, resulting in a Mn-Co-Ni-Cu-O thermistor film with a thickness exceeding 7.7 μm. The surface of the thermistor film remains intact and is well bonded to the silicon dioxide layer without cracking or peeling. The resistivity of the prepared thermistor film is less than 500 Ω, eliminating the need for annealing heat treatment. Compared to existing technologies, this application's approach is simple, efficient, and boasts very high production efficiency and yield.

[0098] This invention uses silver paste to bond 80μm diameter platinum wires to both sides of a thermistor film to form electrodes. Bonding one electrode takes only tens of seconds, resulting in low time and cost. This electrode bonding scheme is very simple, with extremely high bonding efficiency and success rate, which is very beneficial for the actual manufacturing and application of thermistor temperature sensors.

[0099] This invention pre-cuts a single-crystal silicon substrate to 1 / 3 of its thickness, enabling the magnetron sputtered Mn-Co-Ni-Cu-O thermistor film to be divided into independent 5mm×5mm square blocks. This method can reduce the residual stress generated during the growth of the thermistor film, preventing cracking and detachment, and also allows for direct splitting of the prepared thermistor film, which is simple and efficient.

[0100] The negative temperature coefficient thermistor thin-film sensor of the present invention comprises a platinum wire electrode, a Mn-Co-Ni-Cu-O thermistor thin film, insulating silicon dioxide, and a single-crystal substrate. The Mn-Co-Ni-Cu-O thermistor thin film has a spinel structure, which can be viewed as a cubic close-packed structure formed by oxygen ions. Its unit cell structure is AB₂O₄, where A ions occupy oxygen tetrahedral vacancies composed of four oxygen atoms, and B ions occupy oxygen octahedral vacancies composed of six oxygen atoms. The thermistor properties of the spinel-structured thermistor material largely depend on the jumping conductivity between variable-valence cations located in the oxygen octahedra within the crystal structure. In the Mn-Co-Ni-Cu-O thermistor thin film of the present invention, some oxygen ions detach to obtain a certain concentration of oxygen vacancies. These oxygen vacancies not only provide additional electrons but also cause deviations in the material's stoichiometry, changes in the valence state of metal cations, and oxygen octahedral distortion, effectively improving and regulating the material's physical properties and enhancing the thermistor performance of the thin film.

[0101] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A negative temperature coefficient thermistor temperature sensor, characterized in that it comprises a monocrystalline silicon substrate and a negative temperature coefficient thermistor thin film grown on a silicon dioxide layer of the monocrystalline silicon substrate, wherein the negative temperature coefficient thermistor thin film is Mn Co Ni Cu-O thermistor thin film, which has a spinel structure; In the negative temperature coefficient thermistor film, the mass ratio of Mn, Co, Ni, Cu, and O is (28~32):(28~32):(14~16):(0.1~2.5):(20~28). The thickness of the negative temperature coefficient thermistor film is ≥7 μm; The resistance of the negative temperature coefficient thermistor film is less than 700 Ω; The negative temperature coefficient thermistor film is made of Mn Co Ni Cu-O alloy targets are deposited multiple times using physical deposition methods; physical deposition methods include magnetron sputtering, laser molecular beam epitaxy, or electron beam evaporation; the deposition process involves at least two depositions. The spinel unit cell has the structure AB₂O₄, where A ions occupy oxygen tetrahedral voids composed of four oxygen atoms, and B ions occupy oxygen octahedral voids composed of six oxygen atoms.

2. The negative temperature coefficient thermistor temperature sensor according to claim 1, characterized in that, The thickness of the negative temperature coefficient thermistor film is ≥7.5 μm.

3. The negative temperature coefficient thermistor temperature sensor according to claim 1, characterized in that, The thickness of the negative temperature coefficient thermistor film is ≥7.7 μm.

4. The negative temperature coefficient thermistor temperature sensor according to claim 1, characterized in that, The resistance of the negative temperature coefficient thermistor film is less than 500 Ω.

5. The negative temperature coefficient thermistor temperature sensor according to claim 1, characterized in that, The dimensions of the negative temperature coefficient thermistor film are (2~10) mm × (2~10) mm.

6. The negative temperature coefficient thermistor temperature sensor according to claim 1, characterized in that, The dimensions of the negative temperature coefficient thermistor film are 5 mm × 5 mm.

7. The negative temperature coefficient thermistor temperature sensor according to claim 1, characterized in that, Platinum wires are attached to both sides of the negative temperature coefficient thermistor film.

8. The negative temperature coefficient thermistor temperature sensor according to claim 7, characterized in that, The platinum wire is bonded with silver glue.

9. The negative temperature coefficient thermistor temperature sensor according to claim 1, characterized in that, In the negative temperature coefficient thermistor film, the mass ratio of Mn, Co, Ni, Cu, and O is (28~30): (28~30): (15~15.5): (0.5~2): (23~28).

10. The negative temperature coefficient thermistor temperature sensor according to claim 1, characterized in that, In the negative temperature coefficient thermistor film, the mass ratio of Mn, Co, Ni, Cu, and O is 30:30:(15~15.5):(0.5~2):(23~24).

11. The negative temperature coefficient thermistor temperature sensor according to any one of claims 1 to 10, characterized in that, in, The single-crystal silicon substrate is prepared from a single-crystal silicon substrate. The single-crystal silicon substrate has longitudinally and transversely interwoven grooves cut into it to form several small units, which are used to divide the substrate into several single-crystal silicon substrate blocks along the grooves.

12. The negative temperature coefficient thermistor temperature sensor according to claim 11, characterized in that, The groove depth on the monocrystalline silicon substrate is 160 μm to 320 μm.

13. The negative temperature coefficient thermistor temperature sensor according to claim 11, characterized in that, The groove depth is 1 / 4 to 1 / 2 of the thickness of the monocrystalline silicon substrate.

14. The negative temperature coefficient thermistor temperature sensor according to claim 11, characterized in that, The groove depth is 1 / 3 of the thickness of the monocrystalline silicon substrate.

15. The negative temperature coefficient thermistor temperature sensor according to claim 11, characterized in that, The aforementioned small units are several square units.

16. The negative temperature coefficient thermistor temperature sensor according to claim 15, characterized in that, The size of the square unit is (2~10) mm × (2~10) mm.

17. The negative temperature coefficient thermistor temperature sensor according to claim 15, characterized in that, The size of the square unit is 5 mm × 5 mm.

18. A method for manufacturing a negative temperature coefficient thermistor thin film, characterized in that, Includes the following steps: 1) Pre-treat the Mn-Co-Ni-Cu-O alloy target to remove the surface oxide layer and contaminants; 2) Pretreatment of the single-crystal silicon substrate used to prepare the single-crystal silicon substrate block of the negative temperature coefficient thermistor temperature sensor according to any one of claims 11 to 17, to remove surface impurities and contaminants; 3) Using the Mn-Co-Ni-Cu-O alloy target material pretreated in step 1), physical deposition is performed on the single-crystal silicon substrate pretreated in step 2, with at least two depositions, to obtain a negative temperature coefficient thermistor film.

19. The manufacturing method according to claim 18, characterized in that, In step 3), the physical deposition method includes: at the beginning of the deposition, a first sputtering deposition is performed in an inert atmosphere, followed by cooling, a second sputtering deposition is performed, followed by cooling; and so on, to obtain a negative temperature coefficient thermistor film through at least two sputtering depositions.

20. The manufacturing method according to claim 19, characterized in that, The first sputtering coating time is (150~250) min.

21. The manufacturing method according to claim 19, characterized in that, The first sputtering coating time was 200 minutes.

22. The manufacturing method according to claim 19, characterized in that, The second sputtering coating time is (250~350) min.

23. The manufacturing method according to claim 20, characterized in that, The second sputtering coating time was 300 minutes.

24. The manufacturing method according to claim 19, characterized in that, The power of sputtering coating is (200~260) W.

25. The manufacturing method according to claim 19, characterized in that, The power of sputtering coating is 240 W.

26. The manufacturing method according to claim 19, characterized in that, The inert atmosphere is argon or helium.

27. The manufacturing method according to claim 19, characterized in that, The flow rate of the inert atmosphere is (48~52) sccm.

28. The manufacturing method according to claim 26, characterized in that, The flow rate of the inert atmosphere is 50 sccm.

29. The manufacturing method according to claim 19, characterized in that, The vacuum degree of sputtering is (10 -7 ~10 -8 )Torr.

30. The manufacturing method according to claim 19, characterized in that, The sputtering vacuum level is 10. -7 Torr.

31. The manufacturing method according to any one of claims 18 to 30, characterized in that, In step 3), before starting the coating process, the Mn-Co-Ni-Cu-O alloy target is pre-sputtered to remove contaminants and impurities from the target surface.

32. The manufacturing method according to claim 31, characterized in that, It also includes a segmentation step: segmenting the negative temperature coefficient thermistor film obtained in step 3).

33. The manufacturing method according to any one of claims 18 to 30, characterized in that, Divide along the grooves corresponding to the single-crystal silicon substrate.

34. A method for manufacturing a negative temperature coefficient thermistor temperature sensor according to any one of claims 1 to 10, characterized in that, A negative temperature coefficient thermistor temperature sensor is obtained by adding liquid silver paste to both sides of a negative temperature coefficient thermistor film of appropriate size prepared by any of the manufacturing methods described in claims 18 to 33, inserting a platinum wire electrode into the liquid silver paste, stabilizing, curing, and drying.

35. The application of a negative temperature coefficient thermistor temperature sensor according to any one of claims 1 to 17, a negative temperature coefficient thermistor thin film prepared by the manufacturing method according to any one of claims 18 to 33, and a negative temperature coefficient thermistor temperature sensor prepared by the manufacturing method according to claim 34 in integrated circuits, advanced manufacturing, and micro-nano fabrication.

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