Temperature sensor and preparation method thereof

Abstract

The invention provides a temperature sensor and a preparation method thereof, and the method comprises the steps: introducing displacement cations into a transition metal nitride film to form a displacement doped transition metal nitride film, the displacement cations being equivalent to transition metal cations; the crystal structure and the energy band structure of the thin film are regulated and controlled by regulating and controlling the concentration of the displacement cations, so that the conductivity of the thin film is regulated and controlled, and the displacement doped transition metal nitride thin film is obtained; and processing the displacement doped transition metal nitride film through an MEMS technology to obtain the temperature sensor. According to the invention, the high-sensitivity temperature zone of the temperature sensor based on the doped transition metal nitride film can be regulated and controlled in a range from low temperature to room temperature, and the temperature range of the high-sensitivity temperature zone of the temperature sensor is widened.

Description

Technical Field

[0001] The present invention relates to the technical field of temperature sensors, and in particular to a temperature sensor and a preparation method thereof. Background Art

[0002] Transition metal nitride thin films have attracted widespread attention in the field of temperature sensors due to their temperature-dependent resistance over a wide temperature range. Furthermore, these thin films possess significant advantages in temperature sensing due to their high mechanical hardness, high thermal conductivity, high melting point, high corrosion resistance, and high stability. With the advancement of technology and the demand for device miniaturization, temperature sensors based on thin film materials have great development prospects and market potential.

[0003] In practical applications, the optoelectronic properties of transition metal nitride thin films can be modified or regulated based on actual application requirements. The physical properties of transition metal nitride thin films are related to their electronic structure. In transition metal nitrides, the 2s electrons of nitrogen atoms are primarily concentrated in non-bonding orbitals deep within the valence band, while the dp hybrid orbitals formed by the d-orbital electrons of the transition metal atoms and the 2p electrons of nitrogen atoms are located in bonding orbitals below the Fermi level. The density of states at the Fermi level is primarily dominated by the d-orbital electrons of the transition metal, which are responsible for the metallic properties. By adjusting the chemical composition and microstructure of transition metal nitride thin films, their electronic structure can be influenced, thereby achieving the goal of regulating the optoelectronic properties of the films. Introducing a third element into transition metal nitrides is an important method for modifying their chemical composition and microstructure. By regulating the doping content, the optoelectronic properties of transition metal nitride thin films can be fine-tuned, thereby tailoring their performance in temperature sensing applications.

[0004] Currently, most conventional thermometers do not allow measurements between cryogenic and room temperatures. Industrial platinum resistance thermometers follow an industry-standard curve from 73K to 873K, offering good sensitivity across the entire range, but their resistivity is virtually independent of temperature below 40K. In 2015, Yu-Yu Su et al. published a paper titled "Evolution of microstructure invanadium oxide bolometer film during annealing process," which introduced a vanadium oxide-based temperature sensor. While it exhibits high sensitivity near room temperature, it loses its temperature dependence below 200K, making it unsuitable for cryogenic applications.

[0005] A search revealed a Chinese invention patent application with publication number CN112941488A, which discloses a doped transition metal nitride temperature sensor and its preparation method. The method involves introducing cation vacancies into a transition metal nitride film during or after the film is prepared to form a doped transition metal nitride film. The cation vacancy concentration is then controlled to cause a phase transition in the crystal structure of the doped transition metal nitride film, resulting in an ideal doped transition metal nitride film. The doped transition metal nitride film is then used to fabricate a target temperature sensor using a MEMS process. In this patent, when introducing transition metal cation vacancies by doping with low-valent anions, multiple low-valent anions are typically required to construct a single transition metal cation vacancy, resulting in a low efficiency in reducing transition metal cation concentration. Furthermore, doping with low-valent anions requires either introducing a gas containing the doping element during film deposition or using an oxidation method after film preparation, making it difficult to control the doping concentration. Summary of the Invention

[0006] In view of the defects in the prior art, an object of the present invention is to provide a temperature sensor and a preparation method thereof.

[0007] According to one aspect of the present invention, a method for preparing a temperature sensor based on substitutionally doped transition metal nitride thin films is provided, comprising:

[0008] Introducing substitutional cations into a transition metal nitride film to form a substitutionally doped transition metal nitride film, wherein the substitutional cations are equivalent to transition metal cations; regulating the crystal structure and energy band structure of the film by regulating the concentration of the substitutional cations, thereby regulating the conductivity of the film, to obtain a substitutionally doped transition metal nitride film;

[0009] The substitutionally doped transition metal nitride film is processed by MEMS technology to obtain a temperature sensor.

[0010] Furthermore, the crystal structure and energy band structure of the film are regulated by regulating the concentration of the substitutional cations, wherein: the crystal structure includes the degree of lattice distortion, and the energy band structure includes the density of states of transition metal d-orbital electrons at the Fermi level.

[0011] Furthermore, the substitutional cation includes B 3+ 、Al 3+ 、Ga 3+ 、P 3+ 、In 3+ and Tl 3+ Any one of .

[0012] Optionally, the introduction of substitutional cations into the transition metal nitride film is achieved by:

[0013] A high-purity transition metal target and a high-purity doping element target are added into a deposition chamber, where the high-purity doping element target is any one of boron, aluminum, gallium, phosphorus, indium and thallium targets, high-purity argon and nitrogen are introduced, and metal cations corresponding to the high-purity doping element target are introduced into the transition metal nitride film by co-deposition under an argon and nitrogen atmosphere, so that the doping cations replace the transition metal cations in the transition metal nitride;

[0014] Alternatively, a compound target of a transition metal nitride and a high-purity target of a doping element are added into a deposition chamber, where the high-purity target of the doping element is any one of boron, aluminum, gallium, phosphorus, indium and thallium targets, high-purity argon gas is introduced, and doping cations corresponding to the high-purity target of the doping element are introduced into the transition metal nitride film by co-deposition under an argon atmosphere, so that the doping cations replace the transition metal cations in the transition metal nitride.

[0015] Furthermore, the concentration of the substitutional cations is regulated to regulate the crystal structure and energy band structure of the film by adjusting any one of the following methods:

[0016] -Power supply power and voltage applied to the high purity target material doped with the element;

[0017] - Argon gas flow rate introduced into the high-purity target material doped with the element;

[0018] - The distance between the high-purity target material of the doping element and the substrate.

[0019] Furthermore, the high-purity transition metal target is any one of titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium and molybdenum targets; the compound target of the transition metal nitride is any one of titanium nitride, zirconium nitride, hafnium nitride, vanadium nitride, niobium nitride, tantalum nitride, chromium nitride and molybdenum nitride targets.

[0020] Optionally, the introduction of substitutional cations into the transition metal nitride film comprises: adding a compound target of a transition metal nitride containing a doping element into a deposition chamber, introducing high-purity argon gas, and introducing cations corresponding to the doping element into the transition metal nitride film by deposition under an argon atmosphere, so that the doping element cations replace the transition metal cations in the transition metal nitride, wherein the doping element is any one of boron, aluminum, gallium, phosphorus, indium and thallium.

[0021] Furthermore, regulating the concentration of the substitutional cations to regulate the crystal structure and energy band structure of the film includes: adjusting the doping content of the doping element in the transition metal nitride compound target material.

[0022] Furthermore, the transition metal nitride film is deposited by any one of physical vapor deposition, electron beam evaporation and ion beam assisted deposition.

[0023] According to another aspect of the present invention, a temperature sensor is provided. The temperature sensor is prepared using the above-mentioned method for preparing a temperature sensor based on substitutionally doped transition metal nitride thin films.

[0024] Compared with the prior art, the present invention has at least one of the following beneficial effects:

[0025] The present invention proposes to control the crystal structure and band structure of the film, and thus the conductivity, by regulating the impurity concentration of transition metal cations. In transition metal nitrides, the density of states at the Fermi level is primarily dominated by the transition metal's d-orbital electrons, which are responsible for the metallic properties. When an isovalent cation element is introduced into a transition metal nitride film, the isovalent cation replaces the transition metal cations, forming a substitutionally doped transition metal nitride film. The substitutional doping of the isovalent cation reduces the concentration of transition metal d-orbital electrons in the system, lowering the density of states at the Fermi level. Simultaneously, the difference in ionic radius between the doped cation and the transition metal cation causes a change in the interplanar spacing of the film, accompanied by lattice distortion, enhancing electron scattering and reducing the film's conductivity. As the isovalent cation doping concentration increases, the density of states at the Fermi level gradually decreases until a band gap opens, while the lattice distortion increases. During this process, the film's conductivity decreases and its resistance increases, causing the resistance-temperature curve of a temperature sensor based on the doped transition metal nitride film to shift toward a higher temperature range, and the high-sensitivity temperature range to shift from a lower temperature range to a higher temperature range. Based on this principle, the present invention regulates the crystal structure and energy band structure of the temperature-sensitive membrane by controlling the concentration of introduced equivalent cations, thereby regulating the conductivity of the temperature-sensitive membrane, so that the high-sensitivity temperature zone of the temperature sensor based on the doped transition metal nitride film can be regulated in the range from low temperature to room temperature, breaking the limitation that traditional temperature sensors are only suitable for high-sensitivity sensing in low temperature zones or room temperature zones, and broadening the temperature range of the high-sensitivity temperature zone of the temperature sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0027] Figure 1 Schematic diagram of a process for preparing a temperature sensor according to an embodiment of the present invention;

[0028] Figure 2 Schematic diagram of the performance of a temperature sensor in one embodiment of the present invention. DETAILED DESCRIPTION

[0029] The present invention will be described in detail below with reference to specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several variations and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0030] One embodiment of the present invention provides a method for preparing a temperature sensor based on substitutionally doped transition metal nitride thin films, referring to Figure 1 , the method comprising:

[0031] Step 1: Introducing substitutional cations into the transition metal nitride film to form a substitutionally doped transition metal nitride film. In order to avoid introducing vacancy defects during the doping process, the substitutional cations must be equivalent to the transition metal cations. By regulating the concentration of the substitutional cations, the crystal structure and energy band structure of the film are regulated, thereby regulating the conductivity of the film to obtain a target substitutionally doped transition metal nitride film, wherein the target substitutionally doped transition metal nitride film has a high-sensitivity sensing temperature range that meets the requirements.

[0032] Step 2: Process the substitutionally doped transition metal nitride film through MEMS technology to obtain the target temperature sensor.

[0033] In an embodiment of the present invention, a substitutional doped transition metal nitride film is formed by introducing substitutional impurities of transition metal cations into the transition metal nitride film to change the film's crystal structure and band structure. The crystal structure and band structure of the substitutional doped transition metal nitride film are regulated by controlling the concentration of the substitutional cation impurities, thereby regulating the conductivity of the substitutional doped transition metal nitride film. The crystal structure and band structure of the film are regulated by controlling the concentration of the substitutional cations, wherein: the crystal structure includes the degree of lattice distortion, and the band structure includes the density of states of the transition metal d-orbital electrons at the Fermi level. As the concentration of the substitutional cation impurities increases, the degree of lattice distortion of the film increases, and the density of states of the d-orbital electrons at the Fermi level decreases until the band gap opens. During this process, the conductivity of the film gradually weakens and the resistance gradually increases. Therefore, the high-sensitivity sensing temperature range can be controlled by controlling the doping concentration of the substitutional cations in the transition metal nitride film, achieving high-sensitivity temperature sensing over a wide temperature range.

[0034] Substitutional cation doping elements are introduced into the transition metal nitride film. When the doping cation replaces the transition metal cation in the transition metal nitride, the d orbital electron state density at the Fermi level decreases accordingly, and the state density of the transition metal d orbital electron at the Fermi level is regulated by controlling the doping concentration. In order to avoid introducing additional d orbital electron state density during the doping process, the valence electrons of the doping element should avoid containing d orbital electrons. If a high-valent doping cation is introduced, a transition metal cation vacancy will be introduced. If a low-valent doping cation is introduced, a nitrogen vacancy will be introduced. In order to avoid introducing vacancy defects during the doping process, the doping cation needs to be equivalent to the transition metal cation. In some embodiments, the substitutional cation includes B 3+ 、Al 3+ 、Ga 3+ 、P 3+ 、In 3+ and Tl 3+ Any of the above. Introducing equivalent dopant cations can eliminate the influence of vacancy defects and construct a single variable, which is conducive to determining the impact of the replacement of transition metal cations on the high-sensitivity temperature range of the temperature sensor. In other embodiments, other types of cations can also be used, as long as they can achieve the same function as described above.

[0035] The present invention uses thin film samples (substitutionally doped transition metal nitride thin films) with varying doping concentrations to determine their microscopic phase structure, band gap, and resistance-temperature characteristic curves. This allows the corresponding relationship between the doping concentration of the thin film sample and the sensor's high-sensitivity temperature range to be determined. Based on the temperature range requirements of the actual application of the temperature sensor device, the appropriate doping concentration is selected to prepare the thin film sample, which is then processed using MEMS technology to produce the desired temperature sensor.

[0036] In order to change the crystal structure and energy band structure of the film and form a substitutionally doped transition metal nitride film, in some embodiments, substitutional cations are introduced into the transition metal nitride film, which is achieved by the following methods:

[0037] A high-purity transition metal target and a high-purity doping element target are added into a deposition chamber, wherein the high-purity doping element target is any one of boron, aluminum, gallium, phosphorus, indium and thallium targets, and high-purity argon and nitrogen are introduced, wherein the high-purity argon is used as a working gas to bombard the target to produce a glow, and the high-purity nitrogen is used as a reaction gas to provide nitrogen ions in the transition metal nitride, and metal cations corresponding to the high-purity doping element target are introduced into the transition metal nitride film by co-deposition under an argon and nitrogen atmosphere, so that the doped cations replace the transition metal cations in the transition metal nitride; or, a compound target of a transition metal nitride and a high-purity doping element target are added into the deposition chamber, wherein the high-purity doping element target is any one of boron, aluminum, gallium, phosphorus, indium and thallium targets, and high-purity argon is introduced as a working gas to bombard the target to produce a glow, and doping cations corresponding to the high-purity doping element target are introduced into the transition metal nitride film by co-deposition under an argon atmosphere, so that the doping cations replace the transition metal cations in the transition metal nitride.

[0038] For example, a high-purity target of a transition metal element with a purity of 99% to 99.999% and a high-purity boron target, aluminum target, gallium target, phosphorus target, indium target or thallium target with a purity of 99% to 99.999% are added to the deposition chamber, the purity of the argon gas introduced into the high-purity transition metal target and the high-purity doping element target is 99% to 99.999%, the purity of the nitrogen gas introduced into the deposition chamber is 99% to 99.999%, wherein the nitrogen flow rate is in the range of 5 to 50 sccm, and the argon flow rate is in the range of 5 to 50 sccm, and the B is introduced into the transition metal nitride film by co-deposition in an argon and nitrogen atmosphere. 3+ 、Al 3+ 、Ga 3+ 、P 3+ 、In 3+ and Tl 3+ The doping ions are used to replace the transition metal cations in the transition metal nitride.

[0039] Alternatively, a transition metal nitride compound target and a high-purity boron target, aluminum target, gallium target, phosphorus target, indium target or thallium target with a purity of 99% to 99.999% are added to the deposition chamber, the purity of the argon gas introduced into the transition metal nitride compound target and the high-purity target of the doping element is 99% to 99.999%, and the argon flow rate is in the range of 5 to 50 sccm. B is introduced into the transition metal nitride film by co-deposition under an argon atmosphere. 3+ 、Al 3+ 、Ga 3+ 、P 3+ 、In 3+ and Tl 3+ The doping ions are used to replace the transition metal cations in the transition metal nitride.

[0040] In some embodiments, the concentration of substitutional cations is regulated to regulate the crystal structure and energy band structure of the film, and the concentration of substitutional cation impurities is regulated by adjusting any of the following methods: the power and voltage of the power supply applied to the high-purity target material of the doped element, exemplarily, the power and voltage of the power supply applied to the high-purity target material of the doped element are regulated within a power range of 20 to 250 W and a voltage range of 60 to 750 V; the flow rate of argon gas introduced into the high-purity target material of the doped element, exemplarily, for the case of co-depositing the high-purity transition metal target material and the high-purity doped element target material under an argon and nitrogen atmosphere, maintaining The nitrogen flow rate and the argon flow rate of the transition metal high-purity target material remain unchanged, and the argon flow rate of the doped element high-purity target material is adjusted within the range of 5 to 50 sccm. For the case of co-deposition of transition metal nitride compound target material and doped element high-purity target material under argon atmosphere, the argon flow rate of the transition metal nitride compound target material is kept unchanged, and the argon flow rate of the doped element high-purity target material is adjusted within the range of 5 to 50 sccm; the distance between the doped element high-purity target material and the substrate is exemplarily regulated within the range of 50 to 200 mm.

[0041] In some embodiments, the transition metal high-purity target should be non-toxic, and the introduced transition metal cations are combined with nitrogen ions to form a metal compound. For example, the transition metal high-purity target is any one of titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium and molybdenum targets. The transition metal nitride compound target should be non-toxic, and the transition metal nitride is a metal compound. For example, the transition metal nitride compound target is any one of titanium nitride, zirconium nitride, hafnium nitride, vanadium nitride, niobium nitride, tantalum nitride, chromium nitride and molybdenum nitride targets. In other embodiments, other types of transition metal high-purity targets or transition metal nitride compound targets can also be used, as long as they can achieve the same functions as described above.

[0042] The above-mentioned embodiment of the present invention replaces the transition metal cations by doping cations equivalent to the transition metal cations in the transition metal nitride film. Compared with the method of introducing transition metal cation vacancies by doping low-valent anions, the efficiency of reducing the concentration of transition metal cations in the embodiment of the present invention is higher. In addition, when introducing equivalent replacement cations, the method of co-deposition of multiple target materials is used in the preparation process, which can make it easier to control the doping concentration and reduce the difficulty of preparation.

[0043] In some other embodiments, introducing substitutional cations into the transition metal nitride film comprises: adding a compound target of a transition metal nitride containing a doping element into a deposition chamber, introducing high-purity argon gas, and introducing cations corresponding to the doping element into the transition metal nitride film by deposition under an argon atmosphere, so that the doping element cations replace the transition metal cations in the transition metal nitride, wherein the doping element is any one of boron, aluminum, gallium, phosphorus, indium, and thallium. Exemplarily, adding a compound target of a transition metal nitride doped with boron, aluminum, gallium, phosphorus, indium, or thallium into the deposition chamber, introducing high-purity argon gas with a purity of 99% to 99.999%, and the argon gas flow rate is in the range of 5 to 50 sccm, and introducing B into the transition metal nitride film by deposition under an argon atmosphere. 3+ 、Al 3+ 、Ga 3+ 、P 3+ 、In 3+ and Tl 3+ Doping ions allows the doped cations to replace the transition metal cations in the transition metal nitride. Using a single target deposition method, the same doping effect as the above co-deposition can be achieved, with the advantage of simple operation.

[0044] In some embodiments, regulating the concentration of substitutional cations to control the crystal structure and band structure of the thin film includes adjusting the doping content of a doping element in a transition metal nitride compound target. For example, the doping content of the corresponding doping element in a transition metal nitride compound target doped with boron, aluminum, gallium, phosphorus, indium, or thallium is controlled within a range of 5% to 80%.

[0045] In addition to the above-mentioned method for introducing equivalent cationic elements, other methods may be used in some other embodiments to introduce equivalent cationic elements, as long as the same function as above can be achieved.

[0046] In the above embodiments of the present invention, the transition metal nitride thin film is deposited by any one of physical vapor deposition, electron beam evaporation and ion beam assisted deposition.

[0047] The method in the above embodiment of the present invention has a wide range of uses and is applicable to a variety of transition metal elements such as titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, etc.; there are also many methods for introducing cationic doping elements, including co-deposition of high-purity transition metal element targets and high-purity cationic doping element targets in argon and nitrogen atmospheres; co-deposition of transition metal nitride compound targets and high-purity cationic doping element targets in argon atmosphere; deposition of transition metal nitride compound targets doped with cationic elements in argon atmosphere; the method is flexible and can be reasonably selected according to experimental conditions, and has strong universality.

[0048] In one specific embodiment, a substitutionally doped transition metal nitride thin film is prepared by co-deposition of a high-purity target material of a transition metal element and a high-purity target material of a cation doping element using a physical vapor deposition method, comprising the following steps:

[0049] S11. Install high-purity targets of cation-doped elements and high-purity targets of transition metal elements on two target positions of physical vapor deposition equipment, put the cleaned and dried substrate on a tray and place it in a deposition chamber, and evacuate the deposition chamber to a preset ultra-high vacuum condition; high-purity targets of cation-doped elements include any one of boron target, aluminum target, gallium target, phosphorus target, indium target or thallium target; high-purity targets of transition metal elements include any one of titanium target, zirconium target, hafnium target, vanadium target, niobium target, tantalum target, chromium target and molybdenum target; the substrate material should have high thermal conductivity, thermal expansion coefficient and lattice constant similar to those of thin film material, so as to achieve high precision and high stability of temperature sensor. For example, the substrate material includes any one of sapphire, aluminum oxide ceramic, beryllium oxide ceramic, aluminum nitride ceramic, silicon nitride ceramic, silicon carbide ceramic and silicon oxide substrate. The thickness of the substrate should meet the requirements of high thermal conductivity and non-damageability of the substrate. For example, the thickness of the substrate is 80μm to 6mm; the ultra-high vacuum condition range is 10 -5 ~10 -8 Pa.

[0050] S12, turning on the substrate heating power supply, raising the heating temperature to a preset value to bake the substrate surface, so that the substrate reaches the growth temperature of the thin film, and the temperature range is 100 ~ 500 ° C.

[0051] S13. A sufficient amount of high-purity argon gas with a purity of 99% to 99.999% is introduced into the deposition chamber at a flow rate of 5 to 50 sccm to achieve a pressure in the chamber sufficient to cause a glow discharge of the two targets. The transition metal target surface is pretreated using a physical vapor deposition process.

[0052] S14. High-purity nitrogen gas with a purity of 99% to 99.999% is introduced into the deposition chamber of the physical vapor deposition equipment at a flow rate of 5 to 50 sccm. A transition metal nitride film doped with doped ions is deposited on the surface of the substrate using a physical vapor deposition process. The film thickness is 10 nm to 20 μm.

[0053] In step 2, the substitutionally doped transition metal nitride film is processed using a MEMS process to prepare a temperature sensor based on the doped transition metal nitride film. For example, a MEMS temperature sensor based on the substitutionally doped transition metal nitride film is developed through a series of processes, including cleaning the doped transition metal nitride film sample, first-step photolithography, etching the transition metal nitride film, second-step photolithography, metal electrode sputtering, metal electrode lift-off, and third-step photolithography and cutting.

[0054] In a specific embodiment, a target temperature sensor is prepared by using a doped transition metal nitride film through a MEMS process, which can be performed according to the following steps:

[0055] S21, patterning the doped transition metal nitride film, specifically, spin-coating a photoresist on the surface of the deposited temperature-sensitive film, patterning the photoresist through a UV exposure and development process, and transferring the photoresist pattern to the temperature-sensitive film through an ion beam etching process to obtain a desired temperature-sensitive film pattern;

[0056] S22. Patterning an electrode on the surface of the patterned doped transition metal nitride film. Specifically, a photoresist is spin-coated on the surface of the patterned temperature-sensitive film, the photoresist is patterned by UV exposure and development, an electrode material is sputtered onto the patterned photoresist surface by magnetron sputtering, and the photoresist pattern is transferred to the temperature-sensitive film by a lift-off stripping process to obtain a desired electrode pattern. In a preferred embodiment, the electrode material includes, but is not limited to, copper or gold. An adhesive layer is provided between the electrode material and the temperature-sensitive film. The adhesive layer material may include, but is not limited to, chromium, molybdenum, or titanium.

[0057] S23. Cutting the patterned temperature-sensitive film. Specifically, spin-coating a photoresist on the surface of the temperature-sensitive film covering the patterned electrode and patterning the photoresist by ultraviolet exposure to form a cutting pattern. The patterned temperature-sensitive film is then cut into individual devices by a cutting process. Preferred cutting processes include, but are not limited to, laser cutting or blade cutting.

[0058] The embodiment of the present invention regulates the conductivity of the substitutionally doped transition metal nitride film, thereby regulating the resistance-temperature curve of the MEMS temperature sensor based on the substitutionally doped transition metal nitride film, thereby obtaining a temperature sensor with a high-sensitivity and adjustable sensing temperature range; that is, as the concentration of cationic substitutional impurities increases, the conductivity of the film gradually weakens, which causes the resistance-temperature curve of the temperature sensor based on the doped transition metal nitride film to gradually move toward the high temperature zone, and the high-sensitivity temperature zone gradually moves from the low temperature zone to the high temperature zone; that is, by controlling the concentration of the introduced equivalent cations to regulate the conductivity of the temperature sensitive film, thereby regulating the resistance-temperature curve of the temperature sensor based on the doped transition metal nitride film, thereby obtaining a MEMS temperature sensor based on the substitutionally doped transition metal nitride film with an adjustable high-sensitivity and adjustable sensing temperature range.

[0059] Another embodiment of the present invention provides a temperature sensor, which is manufactured using the above-mentioned method for manufacturing a temperature sensor based on substitutionally doped transition metal nitride thin films.

[0060] In a specific embodiment, a method for preparing a MESM temperature sensor based on substitutionally doped transition metal nitride thin film is provided, comprising the following steps:

[0061] S1. Prepare a doped transition metal nitride thin film by physical vapor deposition (PVD) through co-deposition of a high-purity target of transition metal elements and a high-purity target of cation doping elements. During the film deposition process, the equivalent cation doping concentration is regulated to control the crystal structure and energy band structure of the thin film. After the film is deposited, the film is processed using a MEMS process to prepare a temperature sensor. Specifically, the following steps are included:

[0062] S11. Select high-purity zirconium and aluminum targets with a purity of 99% to 99.999%, and install them on the two target positions of the physical vapor deposition equipment respectively. Ultrasonic clean the sapphire substrate and blow dry it with a nitrogen gun and bake it to ensure that the substrate is clean and dry. Place the cleaned sapphire substrate on a tray and place it in the deposition chamber. Evacuate the deposition chamber to 10 -5 ~10 -8 Pa ultra-high vacuum.

[0063] S12. When the vacuum degree in the deposition chamber reaches a preset value, turn on the substrate heating power supply and simultaneously start substrate rotation, raise the heating temperature to 100-500°C and bake the substrate to reach the growth temperature of the thin film.

[0064] S13. The increase of temperature in the deposition chamber will cause the vacuum degree in the sputtering chamber to decrease temporarily. When the vacuum degree in the sputtering chamber is readjusted to 10 -5 ~10 -8 Pa, a sufficient amount of argon gas with a purity of 99% to 99.999% is introduced into the sputtering chamber of the magnetron sputtering equipment, and the argon flow rate is in the range of 5 to 50 sccm. The zirconium target power is set to a fixed value in the range of 20 to 250 W, and the aluminum target power is regulated in the range of 20 to 250 W. Nitrogen gas with a purity of 99% to 99.999% is introduced into the deposition chamber of the physical vapor deposition equipment, and the nitrogen flow rate is in the range of 5 to 50 sccm. When it is observed that the two targets glow discharge at the same time, the baffles of the two targets and the substrate baffle are opened, and the low-energy argon ions and nitrogen ions generated by the glow discharge of argon and nitrogen are sputtered on the surface of the metal zirconium target and the metal aluminum target, and the doped Al is generated by chemical reaction during sputtering. 3+ The zirconium nitride molecules are transported to the surface of the sapphire substrate to be doped with Al 3+ Deposition growth of zirconium nitride thin films.

[0065] S2, in doping Al 3+ After the zirconium nitride film is deposited, the film is processed by MEMS technology to prepare a temperature sensor. The specific process includes the following steps:

[0066] S21, deposited doped Al 3+ The zirconium nitride film was ultrasonically cleaned with acetone, alcohol and water for 5 to 20 minutes each;

[0067] S22, after depositing the doped Al 3+ The zirconium nitride film surface is spin-coated with photoresist, the photoresist is patterned by UV exposure and development process, and the photoresist pattern is transferred to the doped Al by ion beam etching process. 3+ The zirconium nitride film is formed to obtain the desired pattern;

[0068] S23, in the patterned doped Al 3+ Spin-coat the zirconium nitride film surface with photoresist, pattern the photoresist through UV exposure and development process, sputter chromium-gold coating on the patterned photoresist surface through magnetron sputtering process, and transfer the photoresist pattern to the doped Al through lift-off stripping process. 3+ The zirconium nitride film is formed to obtain the desired electrode pattern;

[0069] S24, doping Al on the covered patterned electrode 3+ The zirconium nitride film is spin-coated with photoresist, which is then patterned using UV exposure to form a cutting pattern. The patterned temperature-sensitive film is then cut into individual devices using a laser cutting process.

[0070] Reference Figure 2 As shown, the above-mentioned preparation is based on doped Al 3+ Schematic diagram of high-sensitivity temperature control of zirconium nitride film temperature sensor, Figure 2 The results show that by controlling the Al 3+ The doping concentration of the film is adjusted to adjust the resistance-temperature curve of the film, and the high-sensitivity sensing temperature zone of the temperature sensor is adjusted between the low temperature zone and the room temperature zone.

[0071] In the above-described embodiment of the present invention, the crystal structure and energy band structure of the film are controlled by regulating the concentration of substitutional impurities of the transition metal cations, thereby regulating the conductivity of the film and obtaining an ideal substitutionally doped transition metal nitride film. A temperature sensor based on the substitutionally doped transition metal nitride film is then fabricated using a MEMS process. The embodiment of the present invention proposes regulating the conductivity of the transition metal nitride film by introducing a cationic doping element equivalent to the transition metal cation into the film, thereby regulating the resistance-temperature relationship of the temperature sensor based on the substitutionally doped transition metal nitride film. Ultimately, the highly sensitive sensing temperature range of the temperature sensor is adjustable, enabling highly sensitive temperature sensing over a wide temperature range.

[0072] The above describes specific embodiments of the present invention. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various modifications or variations within the scope of the claims without affecting the essence of the present invention. The above preferred features may be used in any combination as long as they do not conflict with each other.

Claims

1. A method for preparing a temperature sensor based on substitutionally doped transition metal nitride thin films, characterized in that: include: Introducing substitutional cations into a transition metal nitride film to form a substitutionally doped transition metal nitride film, wherein the substitutional cations are equivalent to transition metal cations; regulating the crystal structure and energy band structure of the film by regulating the concentration of the substitutional cations, thereby regulating the conductivity of the film, to obtain a substitutionally doped transition metal nitride film; The substitutionally doped transition metal nitride film is processed by MEMS technology to obtain a temperature sensor.

2. The method for preparing a temperature sensor based on substitutionally doped transition metal nitride thin film according to claim 1, characterized in that: The crystal structure and energy band structure of the film are regulated by regulating the concentration of the substitutional cations, wherein the crystal structure includes the degree of lattice distortion, and the energy band structure includes the state density of transition metal d orbital electrons at the Fermi level.

3. The method for preparing a temperature sensor based on substitutionally doped transition metal nitride thin film according to claim 1, characterized in that: The substitutional cations include B 3+ 、Al 3+ 、Ga 3+ 、P 3+ 、In 3+ and Tl 3+ Any one of .

4. The method for preparing a temperature sensor based on substitutionally doped transition metal nitride thin film according to claim 1, characterized in that: The introduction of substitutional cations into the transition metal nitride film is achieved by the following method: Adding a high-purity transition metal target and a high-purity doping element target into a deposition chamber, wherein the high-purity doping element target is any one of boron, aluminum, gallium, phosphorus, indium and thallium targets, introducing high-purity argon and nitrogen, and introducing metal cations corresponding to the high-purity doping element target into the transition metal nitride film by co-deposition under an argon and nitrogen atmosphere, so that the doping cations replace the transition metal cations in the transition metal nitride; Alternatively, a compound target of a transition metal nitride and a high-purity target of a doping element are added into a deposition chamber, wherein the high-purity target of the doping element is any one of boron, aluminum, gallium, phosphorus, indium and thallium targets, high-purity argon gas is introduced, and doping cations corresponding to the high-purity target of the doping element are introduced into the transition metal nitride film by co-deposition under an argon atmosphere, so that the doping cations replace the transition metal cations in the transition metal nitride.

5. The method for preparing a temperature sensor based on substitutionally doped transition metal nitride thin film according to claim 4, characterized in that: The concentration of the substitutional cations is regulated to regulate the crystal structure and energy band structure of the film by adjusting any of the following methods: -Power supply power and voltage applied to the high purity target material doped with the element; - Argon gas flow rate introduced into the high-purity target material doped with the element; - The distance between the high-purity target material of the doping element and the substrate.

6. The method for preparing a temperature sensor based on substitutionally doped transition metal nitride thin film according to claim 4, characterized in that: The high-purity transition metal target is any one of titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium and molybdenum targets; the compound target of the transition metal nitride is any one of titanium nitride, zirconium nitride, hafnium nitride, vanadium nitride, niobium nitride, tantalum nitride, chromium nitride and molybdenum nitride targets.

7. The method for preparing a temperature sensor based on substitutionally doped transition metal nitride thin film according to claim 1, characterized in that: The method of introducing substitutional cations into the transition metal nitride film comprises: adding a compound target of a transition metal nitride containing a doping element into a deposition chamber, introducing high-purity argon gas, and introducing cations corresponding to the doping element into the transition metal nitride film by deposition under an argon atmosphere, so that the doping element cations replace the transition metal cations in the transition metal nitride, wherein the doping element is any one of boron, aluminum, gallium, phosphorus, indium and thallium.

8. The method for preparing a temperature sensor based on substitutionally doped transition metal nitride thin film according to claim 7, characterized in that: The method of regulating the concentration of the substitutional cations to regulate the crystal structure and energy band structure of the film includes: adjusting the doping content of the doping element in the transition metal nitride compound target material.

9. The method for preparing a temperature sensor based on substitutionally doped transition metal nitride thin film according to any one of claims 4 to 8, characterized in that: The transition metal nitride thin film is deposited by any one of physical vapor deposition, electron beam evaporation and ion beam assisted deposition.

10. A temperature sensor, characterized in that: The temperature sensor is prepared by the method for preparing a temperature sensor based on substitutionally doped transition metal nitride thin film according to any one of claims 1 to 9.

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