A fourth-subgroup transition metal nitride solid solution strain sensitive film with ultra-low temperature coefficient of resistance and preparation method thereof

Abstract

The present invention provides a fourth subgroup transition metal nitride solid solution strain sensitive film with ultra-low temperature coefficient of resistance and a preparation method, which belongs to the field of resistive thin film pressure sensors and thin film strain gauges, and includes a substrate and a functional sensitive film deposited on the substrate, which has a low temperature coefficient of resistance and a stable complete solid solution crystal structure; the present invention adopts a dual-target magnetron co-sputtering or alloyed single-target magnetron sputtering method to obtain a binary A-B, binary A-C transition metal nitride solid solution strain sensitive film with suitable resistivity, ultra-low TCR, and uniform distribution of components; and adopts a three-target magnetron co-sputtering or alloyed single-target magnetron sputtering method to obtain a ternary A-B-C transition metal nitride solid solution strain sensitive film. The multi-component composite film prepared by the present invention is a single-phase solid solution structure; the process is simple and easy to adjust, and the structure is stable; it can be widely promoted in the fields of resistive thin film pressure sensors and thin film strain gauges.

Description

Technical Field

[0001] The present invention belongs to the field of resistive film pressure sensors and film strain gauges, and relates to an ultra-low resistance temperature coefficient strain sensitive film and a preparation method thereof, and in particular to a fourth subgroup transition metal nitride solid solution strain sensitive film with an ultra-low resistance temperature coefficient and a preparation method thereof. Background Art

[0002] The working principle of resistive thin film pressure sensors and thin film strain gauges is to use the piezoresistive effect of thin film sensitive materials, and to detect the response ability of its resistance to its own deformation to achieve the measurement of signals such as force, air pressure and acceleration. Its preparation generally adopts the process of vacuum coating, depositing the thin film resistor layer material on the elastic substrate, and then graphically forming a strain sensitive grid; the strain sensitive grid produces corresponding resistance changes by sensing the strain of the elastic element, and converts the resistance value change into a stable voltage change through a bridge circuit. Resistive thin film pressure sensors have the advantages of compact structure, fast response speed, high sensitivity, and easy integration, and are widely used in aerospace and industrial hydraulic and pneumatic systems. In general, the operating temperature range of thin film pressure sensors in practical applications is -55℃~150℃. Within this temperature range, the strain signal measured by the sensor will be affected by the apparent strain. One of the main ways to reduce the apparent strain is to reduce the resistance change of sensitive materials caused by the test temperature change, that is, the temperature coefficient of resistance (TCR). In view of the above situation, it is necessary to develop strain sensitive thin film materials with ultra-low temperature coefficient of resistance. Titanium nitride has high sensitivity as a functional sensitive material for thin film pressure sensors, but its TCR is usually a large positive value (165~588ppm / ℃). When the magnetron sputtering process is used to deposit titanium nitride thin films, the method to reduce its TCR is mainly to change the gas atmosphere during the sputtering process to regulate the nitrogen and oxygen content inside the film. However, in the actual operation process, oxygen and water vapor will inevitably remain in the vacuum chamber. In addition, oxygen will randomly penetrate from the vacuum flange interface and pipelines, which greatly increases the uncontrollability of the nitrogen and oxygen components inside the film.

[0003] The TCR of the thin film resistor layer can be reduced by mutual compensation between materials, that is, integrating materials with negative TCR and materials with positive TCR to achieve temperature compensation. The Chinese invention patent (201810275443.X) uses series and parallel methods to integrate the TiN film layer with positive TCR and the TaN film layer with negative TCR to reduce the overall TCR of the sensor; the Chinese invention patent (202111640595.3) prepares a stacked structure NiCr / CuNi alloy film with a TCR close to zero; the Chinese invention patent (202110745661.7) prepares a stacked structure Co / Ge alloy film with a TCR close to zero. Although the above work obtains a thin film with a TCR close to zero, the thickness and composition of each layer need to be strictly adjusted at the same time during the preparation of the film, and the process parameters are relatively complex. In addition, there are a large number of defects between the layers in the thin film of the stacked parallel structure, which will greatly affect the cycle stability of the pressure sensor device and it is difficult to meet the application requirements of the pressure sensor in harsh environments.

[0004] Compared with the structure of stacked layers in parallel or in series, the multi-material film prepared by co-sputtering can make the device have a simpler single-layer structure, and its TCR mainly depends on the component content of the material. Reference (OJ Gregory et al., A self-compensated ceramic strain gage for use at elevated temperatures, 2007 IEEE Sensors. 2007, 624-627) uses the co-sputtering method to prepare the indium tin oxide (ITO) / Pt composite sensitive layer, and reduces the TCR of the composite material by optimizing the relative content of ITO and Pt; Reference (M. Petersen et al., Me-DLC films as material for highly sensitive temperature compensated strain gauges, Diamond and Related Materials. 2011, 20 (5–6): 814-818) uses the co-sputtering method to prepare Ag, Ti, W and Ni metal-doped diamond-like carbon films (Me-DLC) on a ceramic substrate, in which the metal component has a positive temperature coefficient and the diamond has a negative temperature coefficient. The final TCR of the material is controlled by optimizing the proportion of each component. However, the crystal structure, elastic modulus and thermal expansion coefficient of the composite film materials obtained in these works are too different. The film is composed of grains of different phases and contains a large number of defects inside. As a result, during the use of thermal cycles and pressurization / decompression cycles of pressure sensor devices, the film will inevitably form more defects such as microcracks, which eventually lead to film cracking. This seriously affects the cycle stability of the device and greatly reduces the service life of the device. Summary of the invention

[0005] According to the technical problems existing in the prior art, the present invention provides a fourth-subgroup transition metal nitride solid solution strain sensitive film with ultra-low temperature coefficient of resistance and a preparation method thereof.

[0006] The prior art adopted in the present invention is:

[0007] A fourth-subgroup transition metal nitride solid solution strain-sensitive film with an ultra-low temperature coefficient of resistance, comprising a substrate and a functional sensitive film deposited on the substrate. The fourth-subgroup transition metal nitride solid solution strain-sensitive film has both a low temperature coefficient of resistance and a stable complete solid solution crystal structure. According to the actual application requirements of the pressure sensor, the present invention adopts a dual-target magnetron co-sputtering or alloyed single-target magnetron sputtering method to obtain a binary AB transition metal nitride solid solution strain-sensitive film or a binary AC transition metal nitride solid solution strain-sensitive film with suitable resistivity, ultra-low TCR, and uniformly distributed components; and adopts a triple-target magnetron co-sputtering or alloyed single-target magnetron sputtering method to obtain a ternary ABC transition metal nitride solid solution strain-sensitive film. Specifically:

[0008] Furthermore, the binary AB or binary AC or ternary ABC transition metal nitride solid solution strain sensitive film is suitable for resistive thin film pressure sensors and thin film strain gauges.

[0009] Furthermore, the crystal structure of the binary AB or binary AC or ternary ABC transition metal nitride solid solution strain sensitive film is a single face-centered cubic (FCC) solid solution phase, components A, B, and C are all FCC structures, and components A, B, and C are in a uniformly dispersed state.

[0010] Furthermore, in the binary AB or binary AC or ternary ABC transition metal nitride solid solution strain sensitive film, component A contains characteristic element Ti, component B contains characteristic element Zr, and component C contains characteristic element Hf. Components A, B, and C are all fourth subgroup transition metal nitrides.

[0011] Furthermore, in the binary AB or binary AC or ternary ABC transition metal nitride solid solution strain sensitive film, components A, B, and C have similar lattice constants, elastic moduli, and thermal expansion coefficients.

[0012] Further, in the binary AB or binary AC or ternary ABC transition metal nitride solid solution strain sensitive film, the resistivity of component A is 112~1230μΩcm, and the TCR is 165~588ppm / ℃. The resistivity of component B is 186~1546μΩcm, and the TCR is -1585~-77ppm / ℃, and the resistivity of component C is 87~2156μΩcm, and the TCR is -3658~-463ppm / ℃.

[0013] Furthermore, in the binary AB or binary AC or ternary ABC transition metal nitride solid solution strain sensitive film, the resistance temperature coefficient of component A is positive, and the resistance temperature coefficients of components B and C are both negative.

[0014] Furthermore, in the binary AB or binary AC or ternary ABC transition metal nitride solid solution strain sensitive film, the film thickness can be uniform and controlled between 300nm and 400nm.

[0015] Furthermore, in the binary AB transition metal nitride solid solution strain sensitive film, the atomic percentage content of Ti is 24.07at.%-26.34at.%, the corresponding atomic percentage content of Zr is 25.12at.%-23.89at.%, and the total atomic percentage content of the remaining non-metals is 50.81at.%-49.77at.%. In the binary AC transition metal nitride solid solution strain sensitive film, the atomic percentage content of Ti is 24.73at.%-27.24at.%, the corresponding atomic percentage content of Hf is 23.45at.%-22.04at.%, and the total atomic percentage content of the remaining non-metals is 51.82at.%-50.72at.%. In the ternary ABC transition metal nitride solid solution strain sensitive film, the atomic percentage content of Ti is 25.06at.%-27.49at.%, the corresponding atomic percentage content of Zr is 11.83at.%-10.37at.%, the corresponding atomic percentage content of Hf is 13.86at.%-11.45at.%, and the total atomic percentage content of the remaining non-metallic atoms is 50.69at.%-49.25at.%. The above non-metallic atoms include N and O.

[0016] Furthermore, in the binary AB, binary AC or ternary ABC transition metal nitride solid solution strain sensitive film, the absolute value of the temperature coefficient of resistance of the film is less than 40 ppm / °C.

[0017] Furthermore, A is TiN, B is ZrN, and C is HfN.

[0018] A method for preparing a fourth-subgroup transition metal nitride solid solution strain-sensitive film with an ultra-low temperature coefficient of resistance includes the following two steps:

[0019] The first preparation method: a method for preparing a fourth-subgroup transition metal nitride solid solution strain-sensitive film with an ultra-low temperature coefficient of resistance by alloying single-target magnetron sputtering, comprising the following steps:

[0020] S1. Prepare target material: prepare alloy solid solution target material by smelting method. The alloy solid solution target material contains characteristic elements Ti and Zr or characteristic elements Ti and Hf or characteristic elements Ti, Zr and Hf.

[0021] S2. Cleaning the substrate: Cleaning is to remove organic stains, natural oxide layer and other impurities on the substrate surface.

[0022] S3. Preparation of functional sensitive film: evenly place the substrate along the diameter of the sample stage, and place the sample stage in a vacuum chamber. Magnetron sputtering is used to prepare the fourth subgroup transition metal nitride solid solution strain sensitive film.

[0023] The second preparation method: a method for preparing a fourth-subgroup transition metal nitride solid solution strain-sensitive film with ultra-low resistance temperature coefficient by multi-target magnetron co-sputtering, comprising the following steps:

[0024] S1. Place the target: Place the target on the sample stage, with the target surfaces parallel or at an angle of 120° to each other.

[0025] S2. Cleaning the substrate: Cleaning is to remove organic stains, natural oxide layer and other impurities on the substrate surface.

[0026] S3. Preparation of functional sensitive film: evenly place the substrate along the diameter of the sample stage, and place the sample stage in a vacuum chamber. Magnetron sputtering is used to prepare the fourth subgroup transition metal nitride solid solution strain sensitive film.

[0027] Furthermore, in S1, the target materials are Ti target materials, Zr target materials and Hf target materials with a purity of 99.999%.

[0028] Further, in S3, the substrate is an elastic material, and the substrates available include but are not limited to insulator materials (Al2O3, quartz, glass, etc.), such as a metal substrate such as stainless steel, on which an insulating layer such as SiO2 is grown, and the thickness of the insulating layer is about 3μm. All substrate surfaces are polished to a mirror surface.

[0029] Furthermore, in S3, the substrate is evenly distributed along the diameter of the sample stage.

[0030] Furthermore, in S3, the sample stage always maintains a rotation speed of 22 s / revolution during the sputtering process.

[0031] Furthermore, in S3, the sputtering process parameters are as follows: substrate temperature 300-400°C, working pressure 0.3-0.4 Pa, sputtering time 100-180 min, Ar flow rate 25 sccm, N2 flow rate 25 sccm, background vacuum degree 3×10 -4 ~4×10 -4 Pa.

[0032] Furthermore, in S3, the sputtering power supply can be arbitrarily replaced by a DC sputtering power supply and a RF sputtering power supply.

[0033] The principle of the present invention is:

[0034] The present invention uses alloyed single-target magnetron sputtering or multi-target magnetron co-sputtering to prepare a multi-element transition metal nitride film, and the metal elements constituting the film all belong to the fourth subgroup of transition metals. HfN, ZrN and TiN with a stoichiometric ratio close to 1:1 are all face-centered cubic structures, and the three have similar lattice constants, thermal expansion coefficients and elastic moduli. ZrN and HfN first appeared in the candidate list of static strain materials with applicable temperatures above 1100°C proposed by NASA in the United States in 2006. When ZrN is suitable for pressure sensors, the resistivity is 186~1546μΩcm and the TCR is -1585~-77ppm / °C. When HfN is suitable for pressure sensors, the resistivity is 87~2156μΩcm and the TCR is -3658~-463ppm / °C. Under normal circumstances, the TCR of HfN and ZrN is negative.

[0035] The present invention proposes a TiN-ZrN or TiN-HfN or TiN-ZrN-HfN multi-element alloy strain sensitive film with ultra-low temperature coefficient of resistance, which utilizes temperature compensation between materials to integrate TiN with positive temperature coefficient of resistance and HfN and ZrN with negative temperature coefficient of resistance into a multi-element metal nitride film of single-phase solid solution with ultra-low temperature coefficient of resistance. TiN, ZrN and HfN grains have similar thermal expansion coefficients and elastic moduli, so the multi-element transition metal composite film has very few defects, and can maintain excellent cycle stability and low resistance drift rate in thermal cycles and stress / strain cycles.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] (1) The present invention provides a strain-sensitive film of the fourth subgroup transition metal nitride solid solution with ultra-low temperature coefficient of resistance. The TiN, ZrN and HfN constituting the multi-component composite film are all face-centered cubic structures, and the components have similar lattice constants, thermal expansion coefficients and elastic moduli. Therefore, the obtained multi-component composite film can be a single-phase solid solution structure. Compared with composite films composed of components with different structures, the single-phase solid solution structure can maintain more stable cycle capacity and longer life in practical applications.

[0038] (2) The present invention provides a strain-sensitive film of the fourth subgroup transition metal nitride solid solution with ultra-low temperature coefficient of resistance. The method of magnetron co-sputtering is used to integrate TiN with a positive temperature coefficient and HfN and ZrN with a negative temperature coefficient into a single-layer multi-component composite film with ultra-low temperature coefficient of resistance. Compared with the reported double-layer heterogeneous film stacked parallel or series structure, the pressure sensor structure prepared by using the single-layer multi-component composite film has the advantages of simple and easy preparation process of the sensitive functional layer, simple processing process of the strain sensitive grid, easy adjustment, and stable structure.

[0039] (3) Based on the above reasons, the present invention can be widely applied in the fields of resistive thin film pressure sensors and thin film strain gauges. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 Schematic diagram of magnetron sputtering of binary AB solid solution alloy nitride thin film samples in Comparative Examples 1, 2 and Example 1.

[0041] Figure 2 1 is the resistivity-temperature (RT) curve of the binary AB solid solution alloy nitride thin film sample in Example 1.

[0042] Figure 3 Schematic diagram of magnetron sputtering of binary AC solid solution alloy nitride thin film samples in Comparative Examples 2, 3 and Example 2.

[0043] Figure 4 This is the RT curve of the binary AC solid solution alloy nitride thin film sample in Example 2.

[0044] Figure 5 Schematic diagram of magnetron sputtering of the ternary ABC solid solution alloy nitride thin film sample in Example 3.

[0045] Figure 6 This is the RT curve of the ternary ABC solid solution alloy nitride film sample in Example 3.

[0046] Figure 7 The resistance change of multi-element alloy nitride strain sensitive film with ultra-low resistance temperature coefficient during temperature cycling. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0048] Comparative Example 1

[0049] In this comparative example, the AB film was prepared by dual-target DC magnetron co-sputtering. Figure 1 The AB film is a binary alloy nitride solid solution TiN-ZrN film.

[0050] 1. Substrate preparation: (100) Si (ρ>3000Ωcm) was selected as the substrate, and a 4-inch Si wafer was divided into several substrates with a size of 10 mm×13 mm using a laser marking machine.

[0051] 2. Cleaning the substrate: The Si substrate was ultrasonically treated with anhydrous ethanol for 30 minutes, then cleaned three times with anhydrous ethanol, acetone, and deionized water in sequence, and then dried with a nitrogen gun.

[0052] 3. Place the substrate: Place several Si substrates evenly along the diameter of the sample stage and then place them into the vacuum chamber.

[0053] 4. Place the target materials: Place the Ti target and Zr target just above the two ends of the sample stage. The target-base distance of the Ti target is 100 mm, and the target-base distance of the Zr target is 105 mm. The two target surfaces form an angle of 120°.

[0054] 5. Substrate pretreatment: When the vacuum degree of the vacuum chamber reaches 5×10 -4 Pa, DC sputtering was used to pre-sputter the target for 10 min, during which the Ar flow rate was set to 30 sccm and the working pressure was 0.4 Pa. RF magnetron sputtering was used to pre-sputter the substrate surface for 20 min, during which the Ar flow rate was set to 30 sccm and the working pressure was 2 Pa. The purpose of pre-sputtering is to remove impurities and natural oxide layers on the target and substrate surfaces.

[0055] 6. Preparation of functional sensitive film: TiN-ZrN film was prepared by dual-target magnetron co-sputtering. In this process, the DC power supply power of the Ti target was set to 250W, the DC power supply power of the Zr target was 70W, the deposition time was 100min, the Ar flow rate was 25sccm, the N2 flow rate was 25sccm, and the working gas pressure was 0.28Pa. The substrate was not additionally heated during the preparation of the functional sensitive film. After the sputtering was completed, the power was turned off and the sample was taken out after waiting for 12h.

[0056] Comparative Example 2

[0057] In this comparative example, the AB thin film was prepared by radio frequency magnetron sputtering.

[0058] 1) Prepare substrate: Select Al2O3 as the substrate and cut Al2O3 into several substrates with a size of 10 mm × 13 mm.

[0059] 2) Clear substrate: The Al2O3 substrate was ultrasonically treated with anhydrous ethanol for 30 minutes, then cleaned three times with anhydrous ethanol, acetone, and deionized water in sequence, and then dried with a nitrogen gun.

[0060] 3) Place the substrate: Place several Al2O3 substrates along the diameter of the sample stage, with a spacing of 3 cm between each substrate and the leftmost substrate 3 cm away from the edge of the sample stage, and then place them into the vacuum chamber.

[0061] 4) Placing the target: the same as step 4 in comparative example 1.

[0062] 5) Substrate pretreatment: same as step 5 in comparative example 1

[0063] 6) Preparation of functional sensitive film: TiN-ZrN film was prepared by dual-target magnetron co-sputtering. In this process, the RF power of the Ti target was set to 70W, the RF power of the Zr target was set to 60W, the deposition time was 180min, the Ar flow rate was 25sccm, the N2 flow rate was 25sccm, and the working gas pressure was 2Pa. The substrate was not additionally heated during the preparation of the functional sensitive film. After the sputtering was completed, the power was turned off and the sample was taken out after waiting for 12h.

[0064] Example 1

[0065] In specific implementation, as a preferred embodiment of the present invention, AB film is prepared by dual-target DC magnetron sputtering. The difference from Comparative Example 1 is that in step 6: TiN-ZrN film is prepared by dual-target magnetron co-sputtering. In this process, the DC power supply power of the Ti target is set to 250W, the DC power supply power of the Zr target is 105W, the deposition time is 100min, the Ar flow rate is 25sccm, the N2 flow rate is 25sccm, and the working gas pressure is 0.28Pa. The substrate is not additionally heated during the preparation of the functional sensitive film. After sputtering, turn off the power and wait for 12 hours before taking out the sample. The remaining steps are consistent with Comparative Example 1.

[0066] Furthermore, the samples prepared in Comparative Examples 1, 2 and Example 1 were subjected to component analysis, and the test method for determining the sample composition was energy dispersive X-ray spectrometer (EDX). In addition, the film thickness of all samples was tested by ellipsometer, and the results showed that the film thickness of the samples prepared in Comparative Examples 1, 2 and Example 1 was 325nm~402nm.

[0067] The structural verification and analysis of Comparative Examples 1 and 2 and Example 1 are as follows:

[0068] For the samples prepared in Comparative Examples 1, 2 and Example 1, the samples consist of TiN phase and ZrN phase. The Ti content of all samples in Comparative Example 1 is higher than the Zr content, and the Ti content of all samples in Comparative Example 2 is lower than the Zr content. In Example 1, the Ti content and Zr content in the prepared samples are close.

[0069] Furthermore, the sample in comparative example 1 is recorded as sample 1, the sample in comparative example 2 is recorded as sample 2, and the sample in embodiment 1 is recorded as sample 3.

[0070] Furthermore, X-ray photoelectron spectroscopy (XPS) was used to characterize the elemental composition content inside the sample after etching for 500s. A comprehensive physical property testing system (PPMS) was used as a variable temperature system and a resistance testing system, and the test temperature range was -50°C-150°C. During the test, the temperature was first kept at 150°C for 30 minutes, and then the temperature was slowly lowered to -50°C. During this period, the resistance signal of the sample was tested in parallel. The cooling rate in this temperature range was 5k / min. Four aluminum wires were bonded to the central area of ​​the film using a bonding instrument, and the resistance of the film was tested using the Van der Pauw method. The RT curve of the resistance of the above-mentioned thin film sample of Example 1 as it changes with temperature is shown in the figure below. Figure 2 shown.

[0071] Furthermore, according to the definition of TCR, the calculation method of TCR at a specific temperature T is:

[0072] (1)

[0073] Among them, △T is the change of ambient temperature, △R0 is the resistance change of the thin film pressure sensor caused by temperature change, and R0 is the resistance value before the ambient temperature changes. The calculation results of the component content of the above samples and the average TCR in the temperature range of -50℃~150℃ are shown in the following table.

[0074] Table 1 shows the test results.

[0075]

[0076] Furthermore, combined with Figure 2 Analyze with Table 1. The absolute values ​​of the TCR coefficients of the samples obtained in Comparative Example 1 and Comparative Example 2 are both greater than 40ppm / ℃. This shows that too high TiN component content in the binary alloy solid solution nitride TiN-ZrN film will cause the TCR of the film to be a large positive value; when the ZrN content inside it is too high, the TCR of the film will be a large negative value. Therefore, only when the Ti content in the binary alloy solid solution nitride TiN-ZrN film is between 24.07at.% and 26.34at.%, and the corresponding Zr content is between 25.12at.% and 23.89at.%, can the film's |TCR| be less than 40ppm / ℃.

[0077] Further, by analyzing the results of Comparative Examples 1 and 2 and Example 1, it is shown that when the Ti content in the TiN-ZrN film is 25.45% and the Zr content is 24.76%, the resistivity of the film is 324.25 μΩcm, and the film has a TCR coefficient close to zero of 9.82 ppm / °C. Obviously, compared with Comparative Examples 1 and 2, the sample of Example 1 has a smaller |TCR|.

[0078] Comparative Example 3

[0079] In this comparative example, the AC thin film was prepared by alloying single target DC sputtering. Figure 3 The AC film is a binary alloy nitride solid solution TiN-HfN film.

[0080] 1) Preparation of target material: A Ti-Hf alloy solid solution target material is prepared by a smelting method. The mass ratio of Ti to Hf in the Ti-Hf alloy solid solution target material is Ti:Hf=80wt%:20wt%.

[0081] 2) Preparation of substrate: same as Comparative Example 1.

[0082] 3) Cleaning the substrate: same as in Comparative Example 1.

[0083] 4) Placing substrate: same as in Comparative Example 1.

[0084] 5) Place the target: Place the AC alloy solid solution target just above both ends of the sample stage, with a target-substrate distance of 100 mm.

[0085] 6) Substrate pretreatment: same as Comparative Example 1.

[0086] 7) Preparation of functional sensitive film: TiN-ZrN film was prepared by alloyed single target DC sputtering. In this process, the DC power supply of the target was set to 180W, the deposition time was 100min, the Ar flow rate was 25sccm, the N2 flow rate was 25sccm, and the working pressure was 0.28Pa. The substrate was not additionally heated during the preparation of the functional sensitive film. After the sputtering was completed, the power was turned off and the sample was taken out after waiting for 12h.

[0087] Comparative Example 4

[0088] In this comparative example, the AC film is prepared by alloying single target RF sputtering. The difference from comparative example 3 is that in step 1: a Ti-Hf alloy solid solution target is prepared by smelting method. The mass ratio of Ti to Hf in the Ti-Hf alloy solid solution target is Ti:Hf=50wt%:50wt%. In step 7: the target RF power supply power is set to 70W during this process, and the deposition time is 200min. The remaining steps are consistent with comparative example 3.

[0089] Example 2

[0090] In specific implementation, as a preferred embodiment of the present invention, a TiN-HfN film is prepared by alloying a single target DC sputtering. The difference from Comparative Example 3 is that in step 1: a Ti-Hf alloy solid solution target is prepared by a smelting method. The mass ratio of Ti to Hf in the Ti-Hf alloy solid solution target is Ti: Hf = 60wt%: 40wt%. In step 6: the DC power supply power of the target in this process is set to 200W. The remaining steps are consistent with Comparative Example 3.

[0091] The structural verification and analysis of Comparative Examples 3 and 4 and Example 2 are as follows:

[0092] The samples in Comparative Examples 3, 4 and Example 2 were selected for electrical transport performance testing. The sample in Comparative Example 3 was recorded as Sample 4, the sample prepared in Comparative Example 5 was recorded as Sample 5, and the sample prepared in Example 2 was recorded as Sample 6. The RT curves of the above samples are shown in Figure 4 shown.

[0093] Furthermore, the calculation results of the component contents of the above samples in Comparative Examples 3, 4 and Example 2 and the average TCR in the temperature range of -50°C to 150°C are shown in the following table.

[0094] Table 2 shows the test results.

[0095]

[0096] Furthermore, combined with Figure 4 and Table 2 for analysis. The absolute values ​​of the TCR coefficients of the samples obtained in Comparative Examples 3 and 4 are both greater than 40ppm / ℃. This indicates that excessive content of TiN component in the binary alloy solid solution nitride TiN-HfN film will cause the TCR of the film to be a large positive value; when the HfN content inside it is too high, the TCR of the film will be a large negative value. Therefore, only when the Ti content in the binary alloy solid solution nitride TiN-HfN film is between 24.73at.% and 27.24at.%, and the corresponding Hf content is between 23.45at.% and 22.04at.%, can the film's |TCR| be less than 40ppm / ℃.

[0097] Furthermore, by analyzing the results of Comparative Examples 3, 4 and Example 2, it is shown that when the Ti content in the TiN-ZrN film is 26.06 at.% and the Zr content is 22.58 at.%, the resistivity of the film is 356.38 μΩcm, and the film has a TCR coefficient close to zero of -16.57 ppm / °C.

[0098] Comparative Example 5

[0099] In this comparative example, a ternary alloy nitride solid solution ABC thin film was prepared by three-target DC magnetron co-sputtering. Figure 5 As shown, the ABC film is a ternary alloy nitride solid solution TiN-ZrN-HfN film. The difference from Comparative Example 1 is that in step 4, the Ti target, Zr target and Hf target are respectively placed above the sample stage, the target-base distance of the Ti target is 100mm, the target-base distance of the Zr target is 105mm, and the target-base distance of the Hf target is 110mm. The three target surfaces are facing the center of the sample stage and are at an angle of 120° to each other. In step 6: the DC power supply power of the Ti target is set to 250W, the DC power supply power of the Zr target is 70W, the DC power supply power of the Hf target is set to 50W, and the deposition time is 80min.

[0100] Comparative Example 6

[0101] In this comparative example, a ternary alloy nitride solid solution ABC thin film is prepared by three-target DC magnetron co-sputtering. The difference from comparative example 5 is that in step 6, the DC power supply power of the Ti target is set to 150W, the DC power supply power of the Zr target is set to 105W, the DC power supply power of the Hf target is set to 70W, and the deposition time is 60min.

[0102] Example 3

[0103] In the specific implementation, as a preferred embodiment of the present invention, a ternary alloy nitride solid solution ABC thin film is prepared by three-target DC magnetron sputtering. The difference from Comparative Example 5 is that in step 6, the DC power supply power of the Ti target is set to 250W, the DC power supply power of the Zr target is 105W, the DC power supply power of the Hf target is set to 70W, and the deposition time is 70min.

[0104] The structural verification and analysis of Comparative Examples 5 and 6 and Example 3 are as follows:

[0105] The samples in Comparative Examples 3, 4 and Example 2 were selected for electrical transport performance testing, the sample in Comparative Example 5 was recorded as Sample 7, the sample prepared in Comparative Example 6 was recorded as Sample 8, and the sample prepared in Example 3 was recorded as Sample 9. The RT curves of the above samples are shown in Figure 6 shown.

[0106] Furthermore, the calculation results of the component contents of the above samples in Comparative Examples 3, 4 and Example 3 and the TCR in the temperature range of -50°C to 150°C are shown in the following table.

[0107] Table 3 shows the test results

[0108]

[0109] Furthermore, combined with Figure 6 and Table 3 for analysis. The absolute values ​​of the TCR coefficients of all samples obtained in Comparative Examples 5 and 6 are greater than 40ppm / ℃. This shows that in the ternary alloy nitride solid solution TiN-ZrN-HfN film, a too high content of TiN with a positive temperature coefficient will cause the TCR of the film to be a large positive value; when the content of ZrN and HfN with a negative temperature coefficient is too high, the TCR of the film will be a large negative value. Therefore, when the Ti content in the ternary alloy nitride solid solution TiN-ZrN-HfN film is between 25.06at.% and 27.49at.%, and the corresponding Zr content is between 11.83at.% and 10.37at.%, and the corresponding Hf content is between 13.86at.% and 11.45at.%, the film's |TCR| can be less than 40ppm / ℃.

[0110] Furthermore, by analyzing the results of comparative examples 1 to 6 and embodiments 1 to 3, it is shown that in the multi-element alloy nitride thin films TiN-ZrN, TiN-HfN and TiN-ZrN-HfN thin films, TiN with positive TCR and ZrN and HfN with negative TCR can compensate each other for TCR. When the Ti content in the multi-element alloy nitride thin film is too high, the film will have a higher positive TCR coefficient, and when the Zr and Hf content in the multi-element alloy nitride thin film is too high, the film will show a higher negative TCR coefficient. By regulating the content ratio of Ti and Zr / Hf in the film, the temperature coefficient of resistance of the multi-element alloy nitride thin film can be made close to zero.

[0111] Furthermore, sample 3 in Example 1, sample 6 in Example 2, and sample 9 in Example 3 were used for temperature stability test. A single temperature cycle was to keep the sample at -50°C for 1.5 hours, then keep it at 150°C for 1.5 hours, and finally return to room temperature. The resistance of the sample was measured at room temperature after the temperature cycle. The resistance change of the sample during 33 temperature cycles is shown in Figure 2. Figure 7 The results show that the resistance change of the multi-element alloy nitride film is stable, indicating its good structural stability.

[0112] 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 strain-sensitive film of a fourth-subgroup transition metal nitride solid solution having an ultra-low temperature coefficient of resistance, characterized in that: The fourth subgroup transition metal nitride solid solution strain sensitive film includes a substrate and a functional sensitive film deposited on the substrate, has a low temperature coefficient of resistance and a stable complete solid solution crystal structure, and specifically includes a binary AB or binary AC or ternary ABC transition metal nitride solid solution strain sensitive film; In the binary AB or binary AC or ternary ABC transition metal nitride solid solution strain sensitive film, component A contains the characteristic element Ti, component B contains the characteristic element Zr, and component C contains the characteristic element Hf; components A, B, and C are all fourth subgroup transition metal nitrides; The resistance temperature coefficient of the component A is positive, and the resistance temperature coefficients of the components B and C are both negative.

2. The strain sensitive film of the fourth subgroup transition metal nitride solid solution with ultra-low temperature coefficient of resistance according to claim 1, characterized in that: The binary AB or binary AC transition metal nitride solid solution strain sensitive film is obtained by dual-target magnetron co-sputtering or alloyed single-target magnetron sputtering; the ternary ABC transition metal nitride solid solution strain sensitive film is obtained by triple-target magnetron co-sputtering or alloyed single-target magnetron sputtering; The crystal structure of the binary AB or binary AC or ternary ABC transition metal nitride solid solution strain sensitive film is a single face-centered cubic solid solution phase, components A, B, and C are all face-centered cubic structures, and components A, B, and C are in a uniformly dispersed state.

3. The fourth-subgroup transition metal nitride solid solution strain sensitive film with ultra-low temperature coefficient of resistance according to claim 1, characterized in that: In the binary AB or binary AC or ternary ABC transition metal nitride solid solution strain sensitive film, the resistivity of component A is 112~1230μΩcm, and the TCR is 165~588ppm / ℃; the resistivity of component B is 186~1546μΩcm, and the TCR is -1585~-77ppm / ℃; the resistivity of component C is 87~2156μΩcm, and the TCR is -3658~-463ppm / ℃.

4. The fourth subgroup transition metal nitride solid solution strain sensitive film with ultra-low temperature coefficient of resistance according to claim 1, characterized in that: The film thickness of the binary AB or binary AC or ternary ABC transition metal nitride solid solution strain sensitive film is uniform and controlled between 300nm and 400nm.

5. The fourth-subgroup transition metal nitride solid solution strain sensitive film with ultra-low temperature coefficient of resistance according to claim 1, characterized in that: In the binary AB or binary AC or ternary ABC transition metal nitride solid solution strain sensitive film: In the binary AB transition metal nitride solid solution strain sensitive film, the atomic percentage content of Ti is 24.07at.%-26.34at.%, the corresponding atomic percentage content of Zr is 25.12at.%-23.89at.%, and the total atomic percentage content of the remaining non-metals is 50.81at.%-49.77at.%; In the binary AC transition metal nitride solid solution strain sensitive film, the atomic percentage content of Ti is 24.73at.%-27.24at.%, the corresponding atomic percentage content of Hf is 23.45at.%-22.04at.%, and the total atomic percentage content of the remaining non-metals is 51.82at.%-50.72at.%; In the ternary ABC transition metal nitride solid solution strain sensitive film, the atomic percentage content of Ti is 25.06at.%-27.49at.%, the corresponding atomic percentage content of Zr is 11.83at.%-10.37at.%, the corresponding atomic percentage content of Hf is 13.86at.%-11.45at.%, and the total atomic percentage content of the remaining non-metals is 50.69at.%-49.25at.%; The above non-metal atoms include N and O.

6. The fourth-subgroup transition metal nitride solid solution strain sensitive film with ultra-low temperature coefficient of resistance according to claim 1, characterized in that: In the binary AB, binary AC or ternary ABC transition metal nitride solid solution strain sensitive film, the absolute value of the temperature coefficient of resistance of the film is less than 40 ppm / °C.

7. The fourth-subgroup transition metal nitride solid solution strain sensitive film with ultra-low temperature coefficient of resistance according to claim 1, characterized in that: A is TiN, B is ZrN, and C is HfN.

8. The fourth-subgroup transition metal nitride solid solution strain sensitive film with ultra-low temperature coefficient of resistance according to claim 1, characterized in that: The binary AB or binary AC or ternary ABC transition metal nitride solid solution strain sensitive film is applied to a resistive film pressure sensor and a film strain gauge.

9. A method for preparing a strain-sensitive film of a Group IV transition metal nitride solid solution having an ultra-low temperature coefficient of resistance as claimed in any one of claims 1 to 8, characterized in that: The preparation method includes an alloyed single-target magnetron sputtering method or a multi-target magnetron co-sputtering method, specifically: The alloyed single target magnetron sputtering method comprises the following steps: S1. Prepare a target material: prepare an alloy solid solution target material by a smelting method; the alloy solid solution target material contains characteristic elements Ti and Zr or characteristic elements Ti and Hf or characteristic elements Ti, Zr and Hf; S2. Cleaning the substrate: the substrate is an elastic material; S3. Preparation of functional sensitive film: evenly arrange the substrate along the diameter of the sample stage, and place the sample stage in a vacuum chamber; prepare the fourth-subgroup transition metal nitride solid solution strain sensitive film by magnetron sputtering; The multi-target magnetron co-sputtering method comprises the following steps: S1. Place the target: Place the target on the sample stage, with the target surfaces parallel or at an angle of 120° to each other; S2. Cleaning the substrate: the substrate is an elastic material; S3. Preparation of functional sensitive film: evenly place the substrate along the diameter of the sample stage, and place the sample stage in a vacuum chamber; and use magnetron sputtering to prepare a fourth-subgroup transition metal nitride solid solution strain sensitive film.

10. The method for preparing a strain sensitive film of a Group IV transition metal nitride solid solution having an ultra-low temperature coefficient of resistance according to claim 9, characterized in that: In the alloyed single target magnetron sputtering method: In S1, the targets are Ti target, Zr target, and Hf target with a purity of 99.999%; In S3, the substrate includes an insulator material and a metal substrate, and when the substrate is a metal, a SiO2 insulating layer is grown on the surface; all substrate surfaces are polished to a mirror surface; In S3, the substrates were evenly distributed along the diameter of the sample stage; during the sputtering process, the sample stage always maintained a rotation speed of 22s / turn; In S3, the sputtering process parameters are: substrate temperature 300~400℃, working pressure 0.3~0.4Pa, sputtering time 100~180min, Ar flow rate 25sccm, N2 flow rate 25sccm, vacuum degree 3×10 -4 ~4×10 -4 Pa; In the multi-target magnetron co-sputtering method: In S1, the targets are Ti target, Zr target, and Hf target with a purity of 99.999%; In S3, the substrate includes an insulator material and a metal substrate, and when the substrate is a metal, a SiO2 insulating layer is grown on the surface; all substrate surfaces are polished to a mirror surface; In S3, the substrates were evenly distributed along the diameter of the sample stage; during the sputtering process, the sample stage always maintained a rotation speed of 22s / turn; In S3, the sputtering process parameters are: substrate temperature 300~400℃, working pressure 0.3~0.4Pa, sputtering time 100~180min, Ar flow rate 25sccm, N2 flow rate 25sccm, vacuum degree 3×10 -4 ~4×10 -4 Pa.

Images