A high performance resistance type deep cryogenic temperature sensor and manufacturing process

Abstract

The present invention provides a high-performance resistive deep cryogenic temperature sensor and a manufacturing process, belonging to the technical field of deep cryogenic temperature sensors. The high-performance resistive deep cryogenic temperature sensor is a laminated structure, including: a device substrate, a sensitive layer film deposited on the device substrate, an electrode layer film deposited on the sensitive layer film, and a cross-finger pattern formed by etching the electrode layer film; the sensitive layer film is a single nitride of a transition metal hafnium or zirconium, and the electrode layer film is also a single nitride of a transition metal hafnium or zirconium. The materials of the two films are the same, but their respective element contents and physical phase systems are different. The present invention can reduce the cracking and shedding of the sensitive layer film and the electrode layer film, improve the life and reliability of the device, and significantly improve the application stability of the device, while ensuring that the temperature sensor has high sensitivity and accuracy; it can be widely promoted in the technical field of low-temperature temperature sensors.

Description

Technical Field

[0001] The present invention belongs to the technical field of cryogenic temperature sensors, and in particular, relates to a high-performance resistance-type cryogenic temperature sensor and a manufacturing process. Background Art

[0002] Temperature is one of the most widely used physical quantities in many research fields and daily life. In physics, cryogenics usually refers to a low temperature state close to or below the temperature of liquid nitrogen (about 77K). This temperature range can meet the extreme needs of many key fields such as special gas storage, medical health, aerospace, and superconductor or semiconductor material testing. It is crucial to achieve real-time and accurate measurement of temperature in cryogenic environments.

[0003] In today's low-temperature environment temperature measurement field, sensors based on thermocouples, thermal resistors or semiconductor elements made by micro-electromechanical system (MEMS) integrated technology are favored due to their miniaturization and strong applicability. Among them, thin-film resistance temperature sensors are the most widely used. Lakeshore, USA, used reactive magnetron sputtering to prepare zirconium oxynitride thin films in an argon-nitrogen-oxygen atmosphere. The composition system of the film is composed of non-conductive zirconium oxide and conductive zirconium nitride. By changing the composition and phase system of the film, its resistance temperature coefficient is improved, thereby improving the sensitivity of the sensor. The sensor can be adapted to different temperature measurement ranges by adjusting the ratio of the conductive phase and the non-conductive phase of zirconium oxynitride. The Cernox series sensors produced are currently widely used at home and abroad. The Chinese invention patent (CN110132445B) proposes to introduce oxygen elements into a near-stoichiometric hafnium nitride film (the ratio of nitrogen to hafnium elements is close to 1) to prepare a hafnium oxynitride sensor, achieving an effect similar to the above-mentioned zirconium oxynitride film.

[0004] The preparation of the above-mentioned existing thin film resistor type low temperature sensors is usually based on the traditional MEMS processing technology, that is, after the deposition of the sensitive thin film layer is completed, a metal material (such as gold) thin film with good conductivity is deposited on it as an electrode layer, and then the electrode layer is patterned in an interdigitated shape through coating, exposure, development and etching, and the overall resistance of the sensitive thin film layer is reduced by connecting resistors in parallel. In these technologies, the stacked structure as the main body of the sensor is composed of heterogeneous thin film materials. The excessive difference in physical properties of heterogeneous materials weakens the application stability of the sensor. For example, the thermal expansion coefficients of zirconium oxynitride and hafnium oxynitride, the materials of the sensitive thin film layer, are approximately 7×10 -6 / K and 6×10 -6 / K, the elastic modulus (Young's modulus) is about 300~400GPa; while the thermal expansion coefficient of metal electrode materials commonly used in devices, such as gold (Au), is about 14.2×10 -6 / K, and the elastic coefficient (Young's modulus) is 78.3GPa. Low-temperature temperature sensors need to work stably for a long time in a wide temperature range from room temperature to nearly 0 K. However, the physical properties of the sensitive layer material and the electrode layer material are very different, which leads to large thermal stress inside the laminated film during the alternating and repeated heating and cooling process of the sensor in actual application. The film is prone to defects such as microcracks, and even cracking or peeling. As a result, the sensor faces reliability problems such as poor thermal cycle stability, performance deterioration and failure during service.

[0005] As an improvement on the traditional device preparation process, the Chinese invention patent (CN110055499A) proposes a method for preparing electrodes directly on the temperature sensitive film without etching for the preparation of the interdigital electrodes of the temperature sensor, removing the process steps of dry etching the electrode layer, thereby reducing the process cost, but the technology does not involve the optimization of the front-end process such as the thin film deposition process, and cannot bring substantial improvement to the application performance of the sensor. In addition, the Chinese invention patent (CN118089974A) proposes to use screen printing to prepare such low-temperature sensors, and place the electrode layer between the substrate and the sensitive layer to protect the electrode layer in the conventional heterostructure from corrosion and make it less likely to fall off and fail, but the technology does not consider starting from the material itself to improve the corrosion resistance of the electrode layer, and this preparation process has poor precision and low efficiency, making it difficult to achieve industrialization. At the same time, the laminated structure of heterogeneous materials is very easy to crack due to thermal expansion mismatch when undergoing high-temperature sintering during the processing process. Therefore, this technology cannot effectively solve the target problem, and will also introduce factors that may reduce the reliability of the device. In summary, the above technologies are unable to solve the device failure problem that is easily caused by the stacked structure of conventional heterogeneous thin film materials.

[0006] As transition metal mononitrides, hafnium nitride and zirconium nitride have good chemical and thermal stability. When used as electrodes, their corrosion resistance is fundamentally superior to that of most common metal materials. Existing studies have confirmed that near-stoichiometric (nitrogen to hafnium or zirconium content ratio is close to 1) hafnium nitride and zirconium nitride materials have a crystal structure of rock salt phase (δ), while the crystal structure of nitrogen-rich hafnium nitride and zirconium nitride in a super-stoichiometric (nitrogen to hafnium or zirconium content ratio is significantly greater than 1) state is cubic phase (c) or orthorhombic phase (o). The thermal expansion coefficient and elastic coefficient between the rock salt phase and the nitrogen-rich phase are not much different, but there is a huge difference in the conductive properties. Hafnium nitride and zirconium nitride in the rock salt phase exhibit excellent metal-like conductivity and a temperature coefficient of resistance close to 0, while hafnium nitride and zirconium nitride in the nitrogen-rich phase have the conductive properties of semiconductors and a temperature coefficient of resistance of extremely negative values. The present invention cleverly utilizes the above-mentioned characteristics of hafnium nitride and zirconium nitride materials, and aims at the application defects of existing low-temperature sensors, and realizes the one-time in-situ continuous growth of hafnium nitride or zirconium nitride laminated films with different conductive properties by regulating the film growth parameters. Specifically, hafnium nitride with semiconductor conductive properties in a mixed state of rock salt phase and nitrogen-rich phase is used as a sensitive layer, and hafnium nitride with metal-like conductivity in rock salt phase is used as an electrode layer. Similarly, a double-layer hafnium nitride film can be replaced with a double-layer zirconium nitride film, and then a design structure using a laminated structure of the same film material as the main body of the sensor device is proposed to optimize the application performance of the low-temperature sensor. Summary of the invention

[0007] In view of the problems existing in the prior art, the present invention proposes a high-performance resistive deep cryogenic temperature sensor and a manufacturing process, which is a thin-film resistive temperature sensor suitable for temperature testing at deep cryogenic conditions and has both high sensitivity and high reliability. At present, the conventional MEMS technology for preparing low-temperature temperature sensors has become mature. On this basis, the present invention optimizes the preparation process of such sensor devices in combination with material properties. By controlling the specific components and phase systems of the same transition metal nitride laminated films, the upper and lower films prepared continuously have obvious differences in electrical conductivity within a wide temperature range. At the same time, since the two films are derived from the same material, their thermal expansion coefficients and elastic coefficients are extremely close, thereby achieving the beneficial effects of simple and easy sensor preparation process, high sensitivity and high reliability.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0009] A high-performance resistive deep cryogenic temperature sensor is a laminated structure, comprising: a device substrate, a sensitive layer film deposited on the device substrate, an electrode layer film deposited on the sensitive layer film, and a finger pattern formed by etching the electrode layer film.

[0010] The sensitive layer film is a single nitride of the transition metal hafnium or zirconium, and the electrode layer film is also a single nitride of the transition metal hafnium or zirconium. The two films are made of the same material, but have different element contents and different phase systems. Specifically:

[0011] Furthermore, the single nitride of the transition metal hafnium or zirconium is hafnium nitride or zirconium nitride.

[0012] Furthermore, in the sensitive layer film, HfN x or ZrN x The nitrogen content in the film is high, and the stoichiometric ratio x of the elements is in the range of 1.1~1.2. It is a mixed system of nitrogen-rich phase and rock salt phase. The resistivity of the sensitive layer film in the mixed phase state is 10 6 ~10 9 μΩ·cm range.

[0013] Furthermore, the electrode layer film is a rock salt phase HfN or ZrN film with a relatively low nitrogen content and a nearly stoichiometric ratio, and the resistivity of the film is at a high conductivity level of 80 to 150 μΩ·cm.

[0014] Furthermore, oxygen impurities may be mixed into the sensitive layer film and the electrode layer film during the preparation process, but the atomic percentage of oxygen does not exceed 15%.

[0015] The present invention is based on the semiconductor properties and metal-like conductive properties of the sensitive layer film and the electrode layer film, respectively. Specifically, under the same wide temperature range, the sensitive layer film and the electrode layer film produce completely different resistance value changes, that is, as the temperature decreases, the resistance value of the sensitive layer film itself increases greatly, while the resistance value of the electrode layer is very small and almost unchanged, thereby ensuring the realization of corresponding temperature-sensitive and conductive properties under the premise that the functions of the laminated films do not conflict. In addition, since the sensitive layer film and the electrode layer film are made of the same material, the thermal expansion coefficient and the elastic coefficient are very close, and the thermal expansion and contraction deformation of the two under the same temperature condition are similar, which greatly reduces the thermal stress that may be generated during the thermal cycle, and can effectively solve the problem of cracking and shedding of the sensitive layer film and the electrode layer film in the conventional heterogeneous material laminated structure. In addition, the use of transition metal nitride materials with excellent corrosion resistance in the electrode layer is also conducive to extending the service life of the device. Therefore, the present invention realizes the rational use of different functions corresponding to different phase component systems of the same material, thereby ensuring the high sensitivity and high precision of the temperature sensor and simplifying its preparation process, while also largely reducing or avoiding the interface connection problems between traditional heterogeneous laminated films, thereby improving the application stability of the sensor.

[0016] Furthermore, the material of the device substrate is preferably a material having a thermal expansion coefficient similar to that of hafnium nitride or zirconium nitride. The optional material of the device substrate includes but is not limited to ceramic materials with good thermal conductivity (Al2O3, ZrO2 and SiO2, etc.), and the surface is polished to a mirror surface.

[0017] Furthermore, the sensitive layer film is made of an over-stoichiometric mixed-phase hafnium nitride or zirconium nitride having semiconductor conductive properties.

[0018] Furthermore, the electrode layer film is made of rock salt phase hafnium nitride or zirconium nitride in a near-stoichiometric ratio with good electrical conductivity.

[0019] Furthermore, the sensitive layer film and the electrode layer film are both hafnium nitride or both zirconium nitride.

[0020] The present invention also provides a method for preparing the above-mentioned high-performance resistance-type cryogenic temperature sensor, comprising the following steps:

[0021] Step S1, device substrate cleaning: remove organic pollutants, metal particles and other impurities on the device substrate surface. The material of the device substrate is preferably a material with a thermal expansion coefficient similar to that of hafnium nitride or zirconium nitride. The optional device substrate material includes but is not limited to ceramic materials with good thermal conductivity (Al2O3, ZrO2 and SiO2, etc.).

[0022] Step S2, preparing the sensitive layer film: using magnetron sputtering technology to deposit the film, the device substrate is mounted on a positioning fixture and placed together in a vacuum sputtering chamber, a metal hafnium target or zirconium target with a purity of not less than 99.95% is used, and a nitrogen-argon mixed gas is introduced into the vacuum chamber to deposit the sensitive layer film. By changing the specific film growth parameters of the sensitive layer film, where the film growth parameters include sputtering mode, sputtering power, sputtering gas pressure, gas flow rate and substrate temperature, the nitrogen content of the prepared sensitive layer film material is significantly higher than that of the metal element, and the corresponding deposited sensitive layer film is HfN x or ZrN x (x=1.1~1.2). The specific preferred film growth parameters include a higher nitrogen flow rate ratio, where the nitrogen flow rate ratio in the mixed gas is 0.3~0.6.

[0023] Step S3, preparation of electrode layer film: After the deposition of the sensitive layer is completed, the sputtering baffle above the substrate is temporarily closed, and only the flow rate of nitrogen and argon introduced into the sputtering chamber is changed to reduce the flow rate ratio of the reaction gas nitrogen. After the equipment is running stably, the sputtering baffle is opened to deposit the electrode layer film in situ on the sensitive layer film. Reducing the nitrogen flow rate ratio makes the nitrogen content of the prepared electrode layer film material equivalent to that of the metal element, and the corresponding electrode layer film deposited is HfN or ZrN. The specific preferred film growth parameters have a lower nitrogen flow rate ratio, and the flow rate ratio of nitrogen in the mixed gas is 0.1.

[0024] Step S4, electrode layer thin film patterning: the electrode layer is patterned by using a dry etching process to form interdigitated electrodes.

[0025] Step S5, sensor device cutting: using a laser cutting machine to cut the sensor chip substrate to obtain a plurality of independent sensor devices.

[0026] Furthermore, in step S2 and step S3, the film growth parameters for preparing the sensitive layer film and the electrode layer film can be changed within a certain range, and ultimately it should be ensured that the conductive properties of the sensitive layer film and the electrode layer film do not change significantly.

[0027] Furthermore, in step S2 and step S3, the technology for preparing the sensitive layer film and the electrode layer film can be replaced by other thin film growth technologies such as pulsed laser deposition, vacuum evaporation coating, atomic layer deposition, metal organic compound chemical vapor deposition, etc. When the growth parameters of various thin film growth technologies are selected, it is necessary to ensure that the components of the prepared sensitive layer and electrode layer films are within their respective corresponding composition ranges, thereby ensuring that the sensitive layer and the electrode layer have semiconductor and metallic resistance-temperature change properties, respectively. It is a known technical content in the field of materials science to achieve changes in the conductive properties of hafnium nitride and zirconium nitride films by adjusting the growth parameter range.

[0028] Furthermore, the thicknesses of the sensitive layer film and the electrode layer film in step S2 and step S3 are 100-500 nm and 200-400 nm respectively.

[0029] The principle of the present invention is: on the basis of the traditional stoichiometric rock salt phase hafnium nitride and zirconium nitride films, the nitrogen content in the film is increased by further increasing the nitrogen flow ratio during the film deposition process, thereby obtaining a mixed phase hafnium nitride and zirconium nitride with a larger absolute value of the temperature coefficient of resistance, which is used as a temperature sensitive film for a temperature sensor. By controlling the film growth parameters, the one-time deposition of hafnium nitride or zirconium nitride stacks used as sensitive layer films and electrode layer films is achieved, thereby realizing the preparation of the main stack structure of the low-temperature sensor based on the same material, wherein the two contact areas formed after the electrode layer is patterned and etched are respectively connected to the external circuit as the input end and the output end for the transmission of electrical signals. A constant current is passed through the two ends of the electrode to the device (or a constant voltage is applied), and the voltage (or current) between the two ends is detected, thereby extracting the temperature value corresponding to the resistance to achieve temperature sensing.

[0030] After adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0031] (1) Based on the large difference in electrical properties between the two phases of hafnium nitride and zirconium nitride materials, continuous in-situ growth of stacked hafnium nitride or zirconium nitride films with different functions can be achieved by simply changing the film growth parameters. Since the stacked structure used in the sensor is composed of the same film material, the thermal expansion coefficient and elastic coefficient of the upper and lower layers are very close. Therefore, while ensuring the high sensitivity and accuracy of the temperature sensor, it solves the problems of thermal stress and strain mismatch of traditional double-layer films of different materials during the heating and cooling test cycle, effectively reduces the cracking and shedding of the sensitive layer film and the electrode layer film, improves the life and reliability of the device, and significantly improves the application stability of the device.

[0032] (2) Based on the above reasons, the present invention can be widely promoted in the field of low-temperature temperature sensor technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 The figure is a schematic diagram of the process flow for preparing a high-performance resistive deep-cryogenic temperature sensor according to the present invention.

[0034] Figure 2 This is a schematic diagram of the structure of a high-performance resistance-type deep cryogenic temperature sensor prepared by the present invention.

[0035] Figure 3 The resistance-temperature relationship corresponding to the hafnium nitride sensor device and the two thin films in the stacked structure in Example 1.

[0036] Figure 4 The resistance-temperature relationship corresponding to the hafnium nitride sensor device and the two thin films in the stacked structure in Example 2.

[0037] Figure 5The resistance-temperature relationship corresponding to the zirconium nitride sensor device and the two thin films in the stacked structure in Example 3. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solution and advantages of the embodiments of the present invention more clear, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0039] Example 1

[0040] In the specific implementation, as a preferred implementation method of the present invention, magnetron sputtering technology and dry etching technology are used to prepare the hafnium nitride thin film stacked low-temperature temperature sensor. The process flow diagram is shown in FIG. Figure 1 The structural diagram of the sensor is shown in Figure 2 shown.

[0041] Step 1, cleaning the substrate: select Al2O3 as the substrate, polish the substrate to a mirror surface, use acetone, anhydrous ethanol, and deionized water ultrasonic cleaning in sequence, blow dry with nitrogen, and place it in a vacuum chamber.

[0042] Step 2, preparing a sensitive layer film: the material of the sensitive layer film is hafnium nitride, and a DC reactive magnetron sputtering coating technology is used, and the background vacuum is 5×10 -4 Pa, nitrogen gas for reaction and argon gas for sputtering were introduced, the nitrogen flow rate was adjusted to account for 0.4 in the total gas flow rate, the working pressure was constant at 0.4Pa, the DC sputtering power was 80W, and a 15-minute pre-sputtering was first performed to stabilize the equipment and remove the residual trace oxygen and water vapor in the chamber as much as possible. Then, formal sputtering was started. A 300-nm-thick hafnium nitride sensitive layer film was grown under the conditions of substrate temperature at room temperature and deposition time of 45 minutes. The X-ray photoelectron spectroscopy test results showed that the atomic percentages of Hf, N, and O in the sensitive layer film were 40.1%, 45.7%, and 14.2%, respectively. The atomic content ratio of N to Hf in the film was 1.14, and the resistivity at room temperature was 2.1×10 7 μΩ·cm.

[0043] Step 3, preparation of electrode layer film: The material of the electrode layer film is hafnium nitride. After the deposition of the above-mentioned sensitive layer film is completed, the sputtering baffle is temporarily closed, the working gas pressure is kept unchanged, and the gas flow rate is changed so that the nitrogen flow rate accounts for 0.1 of the total gas flow rate. After the gas flow rate is stable, the baffle is opened, and a hafnium nitride electrode layer film with a thickness of 300nm is grown under the conditions of substrate temperature at room temperature and deposition time of 30min. The X-ray photoelectron spectroscopy test results show that the atomic percentages of Hf, N, and O in the electrode layer film are 42.7%, 42.9%, and 14.4%, respectively. The atomic content ratio of N and Hf in the film is 1, and the resistivity at room temperature is 113 μΩ·cm.

[0044] Step 4, electrode layer thin film patterning: the electrode layer is patterned by a dry etching process to form interdigitated electrodes.

[0045] Step 5, sensor device cutting: Use a laser cutting machine to cut the sensor chip substrate to obtain multiple independent sensor devices.

[0046] Under the above-mentioned film growth parameter conditions, the prepared hafnium nitride thin film temperature sensor has high sensitivity in a large temperature range, especially at deep low temperatures. The test results show that the sensor has a resistance of 253754.70 ohms at 20K and a temperature coefficient of resistance (TCR) of -20.61%, and a resistance of 195.75 ohms at 300K and a TCR of -0.42%. In the sensor preparation process, by simply changing the film growth parameters and adjusting the composition of the prepared hafnium nitride film, the in-situ continuous preparation of stacked hafnium nitride films for different functions can be achieved, thereby achieving the purpose of the present invention to effectively solve the reliability problem caused by the traditional stacked structure while improving the sensitivity and accuracy of the sensor.

[0047] Example 2

[0048] In the specific implementation, as a preferred implementation method of the present invention, magnetron sputtering technology and dry etching technology are used to prepare the hafnium nitride thin film stacked low-temperature temperature sensor. The process flow diagram is shown in FIG. Figure 1 The structural diagram of the sensor is shown in Figure 2 shown.

[0049] Step 1, cleaning the substrate: select ZrO2 as the substrate, use acetone, anhydrous ethanol, and deionized water for ultrasonic cleaning in sequence, blow dry with nitrogen, and place it in a vacuum chamber.

[0050] Step 2, preparing a sensitive layer film: the material of the sensitive layer film is hafnium nitride, and a DC reactive magnetron sputtering coating technology is used, and the background vacuum is 5×10 -4Pa, nitrogen gas for reaction and argon gas for sputtering were introduced, the nitrogen flow rate was adjusted to 0.6 in the total gas flow rate, the working pressure was constant at 0.4Pa, the DC sputtering power was 80 W, and a 15-minute pre-sputtering was first performed to stabilize the equipment and remove the residual trace oxygen and water vapor in the chamber as much as possible. Then the formal sputtering was started. A 100-nm-thick hafnium nitride sensitive layer film was grown under the conditions of substrate temperature at room temperature and deposition time of 20 minutes. The X-ray photoelectron spectroscopy test results showed that the atomic percentages of Hf, N, and O in the sensitive layer film were 39.0%, 46.7%, and 14.3%, respectively. The atomic content ratio of N and Hf in the film was 1.2, and the resistivity at room temperature was 8.2×10 8 μΩ·cm.

[0051] Step 3, preparation of electrode layer film: The material of the electrode layer film is hafnium nitride. After the deposition of the above-mentioned sensitive layer film is completed, the sputtering baffle is temporarily closed, the working gas pressure is kept unchanged, and the gas flow rate is changed so that the nitrogen flow rate accounts for 0.1 of the total gas flow rate. After the gas flow rate is stable, the baffle is opened, and a hafnium nitride electrode layer film with a thickness of 200nm is grown under the conditions of substrate temperature at room temperature and deposition time of 20min. The X-ray photoelectron spectroscopy test results show that the atomic percentages of Hf, N, and O in the electrode layer film are 42.9%, 43.0%, and 14.1%, respectively. The atomic content ratio of N and Hf in the film is 1, and the resistivity at room temperature is 139μΩ·cm.

[0052] Step 4, electrode layer thin film patterning: the electrode layer is patterned by a dry etching process to form interdigitated electrodes.

[0053] Step 5, sensor device cutting: Use a laser cutting machine to cut the sensor chip substrate to obtain multiple independent sensor devices.

[0054] Under the above-mentioned film growth parameter conditions, the prepared hafnium nitride thin film temperature sensor has high sensitivity in a large temperature range, especially at deep low temperatures. Test results show that the resistance of the hafnium nitride thin film temperature sensor at 20K is 1982175.67 ohms, and the temperature coefficient of resistance (TCR) is -23.92%. The resistance at 300K is 1136.94 ohms, and the TCR is -0.57%. In the sensor preparation process, by simply changing the film growth parameters and adjusting the composition of the prepared hafnium nitride film, the in-situ continuous preparation of stacked hafnium nitride films for different functions can be achieved, thereby achieving the purpose of the present invention to effectively solve the reliability problem caused by the traditional stacked structure while improving the sensitivity and accuracy of the sensor.

[0055] Example 3

[0056] In the specific implementation, as a preferred implementation method of the present invention, magnetron sputtering technology and dry etching technology are used to prepare zirconium nitride thin film stacked low-temperature temperature sensor. The process flow diagram is as follows: Figure 1 The structural diagram of the sensor is shown in Figure 2 shown.

[0057] Step 1, cleaning the substrate: select SiO2 as the substrate, use acetone, anhydrous ethanol, and deionized water for ultrasonic cleaning in sequence, blow dry with nitrogen, and place it in a vacuum chamber.

[0058] Step 2, preparing the sensitive layer film: the material of the sensitive layer film is zirconium nitride, and the DC reactive magnetron sputtering coating technology is adopted, and the background vacuum is 5×10 -4 Pa, nitrogen gas for reaction and argon gas for sputtering were introduced, the nitrogen flow rate was adjusted to 0.3 in the total gas flow rate, the working pressure was constant at 0.4Pa, the DC sputtering power was 130 W, and a 15-minute pre-sputtering was first performed to stabilize the equipment and remove the residual trace oxygen and water vapor in the chamber as much as possible. Then the formal sputtering was started. A 500-nm-thick zirconium nitride sensitive layer film was grown under the conditions of substrate temperature at room temperature and deposition time of 60 minutes. The X-ray photoelectron spectroscopy test results showed that the atomic percentages of Zr, N, and O in the sensitive layer film were 41.1%, 45.3%, and 13.6%, respectively. The atomic content ratio of N to Zr in the film was 1.1, and the resistivity at room temperature was 5.6×10 6 μΩ·cm.

[0059] Step 3, preparation of electrode layer film: The electrode layer film is made of zirconium nitride. After the deposition of the above-mentioned sensitive layer film is completed, the sputtering baffle is temporarily closed, the working gas pressure is kept unchanged, and the gas flow rate is changed so that the nitrogen flow rate accounts for 0.1 of the total gas flow rate. After the gas flow rate is stable, the baffle is opened, and a zirconium nitride electrode layer film with a thickness of 400nm is grown under the conditions of substrate temperature at room temperature and deposition time of 35min. The X-ray photoelectron spectroscopy test results show that the atomic percentages of Zr, N, and O in the electrode layer film are 43.2%, 43%, and 13.8%, respectively. The atomic content ratio of N to Zr in the film is 1, and the resistivity at room temperature is 98μΩ·cm.

[0060] Step 4, electrode layer thin film patterning: the electrode layer is patterned by a dry etching process to form interdigitated electrodes.

[0061] Step 5, sensor device cutting: Use a laser cutting machine to cut the sensor chip substrate to obtain multiple independent sensor devices.

[0062] Under the above film growth parameter conditions, the prepared zirconium nitride thin film temperature sensor has high sensitivity in a large temperature range, especially at deep low temperatures. The test results show that the resistance of the zirconium nitride thin film temperature sensor is 2175.67 ohms at 20K, and the temperature coefficient of resistance (TCR) is -14.39%. The resistance at 300K is 130.94 ohms, and the TCR is -0.26%. In the sensor preparation process, by simply changing the film growth parameters and adjusting the composition of the prepared zirconium nitride film, the in-situ continuous preparation of laminated zirconium nitride films for different functions can be achieved, thereby achieving the purpose of the present invention to effectively solve the reliability problem caused by the traditional laminated structure while improving the sensitivity and accuracy of the sensor.

[0063] The performance of hafnium nitride and zirconium nitride thin film low-temperature sensors prepared under different film growth parameters was tested using a liquid helium-free comprehensive physical property measurement system (PPMS DynaCool). The test temperature range was 1.9K~300K, and the results were Figure 3 , Figure 4 , Figure 5 The resistance-temperature relationship is shown.

[0064] Compared with the existing technology, the hafnium nitride and zirconium nitride thin film low-temperature sensors prepared by the present invention have a larger negative TCR value in a wide temperature range, that is, when the ambient temperature changes by the same amount in the same interval, the magnitude of the change in the sensor's own resistance value is larger, indicating that the sensor can achieve more precise temperature measurement in a wide temperature range from room temperature to nearly 0 K. More importantly, the present invention can significantly reduce the various factors that potentially affect the reliability and durability of such sensors during the conventional manufacturing process due to the heterogeneous material stacking structure. This is of great significance to many fields that require the use of low-temperature environments, such as aerospace, cryogenic electronics, cryogenic physics, materials science, special gas storage, and medical and health care.

[0065] The above-described embodiments merely express the implementation methods of the present invention, but they should not be understood as limiting the scope of the present invention. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A high performance resistance type deep cryogenic temperature sensor, characterized in that: The high-performance resistance-type deep cryogenic temperature sensor is a laminated structure, including: a device substrate, a sensitive layer film deposited on the device substrate, an electrode layer film deposited on the sensitive layer film, and an interdigital pattern formed by etching the electrode layer film; The sensitive layer film is a single nitride of a transition metal hafnium or zirconium, and the electrode layer film is also a single nitride of a transition metal hafnium or zirconium. The two films are made of the same material, but have different element contents and different physical phase systems. The sensitive layer film and the electrode layer film are specifically: The sensitive layer film adopts a mixed phase hafnium nitride or zirconium nitride with an overstoichiometric ratio and semiconductor conductivity; the single nitride in the sensitive layer film is HfN x or ZrN x , the nitrogen content in the sensitive layer film is high, and the stoichiometric ratio x of the element is in the range of 1.1~1.2; The electrode layer film adopts a rock salt phase hafnium nitride or zirconium nitride with a near stoichiometric ratio and good conductivity; the single nitride in the electrode layer film is HfN or ZrN, and the electrode layer film has a low nitrogen content and is a rock salt phase HfN or ZrN film with a near stoichiometric ratio.

2. A high performance resistance type cryogenic temperature sensor according to claim 1, characterized in that: The sensitive layer film and the electrode layer film are specifically: The sensitive layer film is a mixed system of nitrogen-rich phase and rock salt phase. The resistivity of the sensitive layer film in the mixed phase state is 10 6 ~10 9 μΩ·cm range; The resistivity of the electrode layer film is at a high level of 80-150 μΩ·cm.

3. A high performance resistance type deep cryogenic temperature sensor according to claim 1, characterized in that: Oxygen impurities may exist in the sensitive layer film and the electrode layer film during the preparation process, but the atomic percentage of oxygen does not exceed 15%.

4. A high performance resistance type cryogenic temperature sensor according to claim 1, characterized in that: The device substrate is made of a material having a thermal expansion coefficient similar to that of hafnium nitride or zirconium nitride, and the surface is polished to a mirror surface.

5. A high performance resistance type cryogenic temperature sensor according to claim 4, characterized in that: The device substrate is made of ceramic material.

6. A high performance resistance type cryogenic temperature sensor according to claim 1, characterized in that: The sensitive layer film and the electrode layer film are both hafnium nitride or zirconium nitride.

7. A method for preparing a high-performance resistance-type cryogenic temperature sensor according to any one of claims 1 to 6, characterized in that: The steps include: Step S1, cleaning the device substrate; Step S2, preparing a sensitive layer film: using magnetron sputtering technology to deposit a film, mounting the device substrate on a positioning fixture and placing them together in a vacuum sputtering chamber, using a metal hafnium target or zirconium target with a purity of not less than 99.95%, introducing a mixed gas of nitrogen and argon into the vacuum chamber to deposit a sensitive layer film; by changing the specific film growth parameters of the sensitive layer film, the nitrogen content of the prepared sensitive layer film material is higher than that of the metal element, and the corresponding deposited sensitive layer film is HfN x or ZrN x , wherein x=1.1~1.2; the film growth parameters include sputtering mode, sputtering power, sputtering gas pressure, gas flow rate and substrate temperature; Step S3, preparing an electrode layer film: after the sensitive layer is deposited, close the sputtering baffle above the substrate, and only change the flow rate of nitrogen and argon introduced into the sputtering chamber to reduce the flow rate ratio of the reaction gas nitrogen. After the equipment is running stably, open the sputtering baffle to in-situ deposit the electrode layer film on the sensitive layer film; reducing the nitrogen flow rate ratio makes the nitrogen content of the prepared electrode layer film material equivalent to that of the metal element, and the corresponding deposited electrode layer film is HfN or ZrN; Step S4, electrode layer thin film patterning: the electrode layer is patterned by a dry etching process to form interdigitated electrodes; Step S5, sensor device cutting: using a laser cutting machine to cut the sensor chip substrate to obtain a plurality of independent sensor devices.

8. The method for preparing a high-performance resistance-type cryogenic temperature sensor according to claim 7, characterized in that: In the preparation method: In the step S2, the flow rate ratio of nitrogen in the mixed gas is 0.3-0.6; the technology for preparing the sensitive layer film can be replaced by pulsed laser deposition, vacuum evaporation coating, atomic layer deposition, metal organic compound chemical vapor deposition film growth technology; the thickness of the sensitive layer film is 100-500nm; In the step S3, the flow rate ratio of nitrogen in the mixed gas is 0.1; the technology for preparing the electrode layer film can be replaced by pulsed laser deposition, vacuum evaporation coating, atomic layer deposition, and metal organic compound chemical vapor deposition thin film growth technology; the thickness of the electrode layer film is 200~400nm.

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