A multilayer thin film thermocouple suitable for high temperature cycling measurements and a method of making the same

Abstract

The application belongs to the technical field of high-temperature thin films, and particularly relates to a multilayer thin film thermocouple suitable for high-temperature cyclic measurement and a preparation method thereof. The multilayer thin film thermocouple suitable for high-temperature cyclic measurement comprises, from bottom to top, a bottom insulating layer, a bottom bonding layer, a functional material layer, a top bonding layer and a top insulating layer, the functional material layer comprises a thermocouple function A end and a thermocouple function B end which are interconnected, and the top bonding layer and the bottom bonding layer are used to coat the functional material layer after being fused with each other under high-temperature conditions. The structure of the multilayer thin film thermocouple is bottom insulating layer-bottom bonding layer-functional material layer-top bonding layer-top insulating layer, the bonding layer with low stress under high temperature is fused to coat the functional material layer, the stress interface of the functional material layer is effectively reduced, and the stability is improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of high-temperature thin films, and particularly relates to a multilayer thin film thermocouple suitable for high-temperature cyclic measurement and a preparation method thereof. BACKGROUND

[0002] In the aspect of traditional contact temperature measurement, although the high-temperature thermocouple can meet the requirement of temperature range, the structure of the high-temperature thermocouple cannot be closely connected with the material and easily destroys the integrity of the measured component, which will seriously affect the accuracy of temperature measurement and the structural strength of the component. In contrast, the thin film thermocouple has the advantages of high temperature measurement accuracy, fast response speed, good stability and small structural influence. After a specific structure is deposited on the surface of the measured object through a thin film preparation technology, the running state of the component can be reflected in real time, which is helpful to evaluate the material reliability and develop higher performance products.

[0003] However, the thin film thermocouple in the high-temperature section (> 900℃) has not been widely used, and the main reason is that the thin film material is prone to film peeling and circuit conduction failure during use. These phenomena seriously affect the service life and detection effect of the device, and restrict the application and development of the thin film thermocouple in the high-temperature temperature measurement field. SUMMARY

[0004] The present application provides a multilayer thin film thermocouple suitable for high-temperature cyclic measurement.

[0005] The present application also provides a preparation method of the multilayer thin film thermocouple.

[0006] According to the multilayer thin film thermocouple suitable for high-temperature cyclic measurement of the specific embodiment of the present application, from bottom to top, it comprises a bottom insulating layer, a bottom bonding layer, a functional material layer, a top bonding layer and a top insulating layer, the functional material layer comprises a thermocouple function A end and a thermocouple function B end which are in communication with each other, wherein,

[0007] The top bonding layer and the bottom bonding layer can be fused with each other under high-temperature conditions and coat the functional material layer.

[0008] The multilayer thin film thermocouple further comprises a substrate, and the bottom insulating layer is arranged on the substrate.

[0009] The internal stress generated by the multilayer thin film thermocouple under high temperature can be dissipated through the bonding layers (the bottom bonding layer and the top bonding layer), which effectively improves the stability and bonding force between the multiple interfaces (the bonding layer and the insulating layer, the bonding layer and the functional material layer). The top bonding layer and the bottom bonding layer can disappear and fuse at the interface under high temperature, completely wrap the functional material layer, reduce the thermal stress of the functional material during testing, and greatly improve the testing accuracy and cyclic repetition stability during operation.

[0010] According to the multilayer thin film thermocouple for high temperature cycle measurement of the embodiment of the present application, the material of the bottom adhesive layer and the top adhesive layer is independently selected from aluminum target material, silicon target material, silicon carbide target material or zirconium target material.

[0011] Preferably, the material of the bottom adhesive layer and the top adhesive layer is selected from silicon target material or silicon carbide target material.

[0012] According to the multilayer thin film thermocouple for high temperature cycle measurement of the embodiment of the present application, the material of the bottom adhesive layer and the top adhesive layer is independently selected from aluminum target material, silicon target material, silicon carbide target material or zirconium target material.

[0013] Preferably, the material of the top adhesive layer and the bottom adhesive layer is selected from aluminum target material.

[0014] According to the multilayer thin film thermocouple for high temperature cycle measurement of the embodiment of the present application, the material of the thermocouple functional A end is selected from indium tin oxide, constantan alloy, tungsten-rhenium alloy or nickel-chromium alloy, and / or,

[0015] The material of the thermocouple functional B end is selected from Pt, constantan alloy, tungsten-rhenium alloy or nickel-chromium alloy.

[0016] According to the preparation method of the multilayer thin film thermocouple for high temperature cycle measurement of the embodiment of the present application, the method comprises the following steps:

[0017] (1) sputtering a bottom adhesive layer on a substrate;

[0018] (2) sputtering a bottom adhesive layer on the bottom adhesive layer;

[0019] (3) sputtering a thermocouple functional A end and a thermocouple functional B end on the bottom adhesive layer, respectively, and the thermocouple functional A end and the thermocouple functional B end are connected to form a functional material layer;

[0020] (4) sputtering a top adhesive layer on the functional material layer;

[0021] (5) sputtering a top adhesive layer on the top adhesive layer,

[0022] wherein the top adhesive layer and the bottom adhesive layer prepared can be fused with each other under high temperature conditions to coat the functional material layer.

[0023] According to the preparation method of the multilayer thin film thermocouple for high temperature cycle measurement of the embodiment of the present application, in step (1), when sputtering a bottom adhesive layer on a substrate,

[0024] The sputtering parameters are: the pressure is 1.0-4.0 Pa, the sputtering power is 20-200 W; the sputtering atmosphere is argon, oxygen or nitrogen; preferably, the flow ratio of argon:oxygen is 4-6:1, the power is 130-170 w, or the flow ratio of nitrogen:oxygen is 4-6:1, the power is 130-170 w;

[0025] After sputtering, annealing is performed at 500-1300 ℃;

[0026] The target material selected for the bottom insulating layer includes an aluminum target material, a silicon target material, a silicon carbide target material or a zirconium target material.

[0027] In step (5), when sputtering the top insulating layer on the top adhesive layer,

[0028] The sputtering parameters are: the pressure is 1.0-4.0 Pa, the sputtering power is 20-200 W; the sputtering atmosphere is argon, oxygen or nitrogen; preferably, the flow ratio of argon:oxygen is 4-6:1, the power is 130-170 w, or the flow ratio of nitrogen:oxygen is 4-6:1, the power is 130-170 w;

[0029] After sputtering, annealing is performed at 500-1300 ℃;

[0030] The target material selected for the top insulating layer includes an aluminum target material, a silicon target material, a silicon carbide target material or a zirconium target material.

[0031] The top insulating layer and the bottom insulating layer can select the same target material or different target materials.

[0032] According to the preparation method of the multilayer thin film thermocouple suitable for high temperature cycle measurement according to the specific embodiment of the present application, in step (2), when sputtering the bottom adhesive layer on the bottom insulating layer,

[0033] The sputtering parameters are: the pressure is 1.5-2.5 Pa, the sputtering power is 100-200 W; the sputtering atmosphere is argon, oxygen or nitrogen; preferably, the flow ratio of argon:oxygen is 4-6:1, the power is 130-170 w, or the flow ratio of nitrogen:oxygen is 4-6:1, the power is 130-170 w;

[0034] After sputtering, annealing is performed at 300-1500 ℃;

[0035] The target material selected for the bottom adhesive layer includes an aluminum target material, a silicon target material, a silicon carbide target material or a zirconium target material.

[0036] In step (4), when sputtering the top adhesive layer on the functional material layer,

[0037] The parameters of sputtering are as follows: the pressure is 1.5-2.5 Pa, the sputtering power is 100-200 W, the sputtering atmosphere is argon, oxygen or nitrogen, the flow ratio of argon to oxygen is 4-6:1, the power is 130-170 W, or the flow ratio of nitrogen to oxygen is 4-6:1, and the power is 130-170 W.

[0038] After sputtering, annealing is performed at 300-1500 DEG C.

[0039] The selected target material of the top bonding layer includes an aluminum target material, a silicon target material, a silicon carbide target material or a zirconium target material.

[0040] The top bonding layer and the bottom bonding layer can be selected from the same target material or different target materials.

[0041] According to the preparation method of the multilayer thin film thermocouple suitable for high-temperature cycle measurement in the embodiment of the present application, in step (3), when the thermocouple function A end is prepared,

[0042] The material of the thermocouple function A end is selected from indium tin oxide, constantan alloy, tungsten rhenium alloy or nickel chromium alloy.

[0043] The parameters of sputtering are as follows: the pressure is 0.5-3 Pa, the sputtering power is 80-120 W, and the sputtering temperature is 180-220 DEG C.

[0044] The thickness of the prepared thermocouple function A end is 1.0-4.0 mu m.

[0045] The purity of the indium tin oxide target material is greater than 4N, and the content of SnO2 is 5-30 wt%.

[0046] According to the preparation method of the multilayer thin film thermocouple suitable for high-temperature cycle measurement in the embodiment of the present application, in step (3), when the thermocouple function B end is prepared,

[0047] The material of the thermocouple function B end is selected from platinum, constantan alloy, tungsten rhenium alloy or nickel chromium alloy.

[0048] The parameters of sputtering are as follows: the pressure is 2-4 Pa, the sputtering power is 50-150 W, and the sputtering temperature is 250-350 DEG C.

[0049] The thickness of the prepared thermocouple function B end is 0.4-8 mu m.

[0050] In the present application, the sputtering method includes thin film preparation methods such as thermal evaporation, ion beam evaporation, chemical thermal vapor deposition, plasma chemical vapor deposition, etc.

[0051] In the present application, the temperature of sputtering can promote the temperature stability of crystal growth. When the temperature is reduced, the thin film is prone to cracking and falling off from the substrate, resulting in failure.

[0052] Meanwhile, the application achieves the purpose of controlling the oxygen content in the thin film by adjusting the relationship between the gas flow ratio and the power. When the oxygen proportion in the gas flow ratio is large and the power is low, the target material is prone to be oxidized, which reduces the sputtering thin film efficiency. If the oxygen proportion is not large and the power is large, the sputtering target material is prone to be insufficiently oxidized, and in the subsequent processing, the thin film is further prone to be greatly oxidized and prone to defects. When the power is unchanged and the oxygen content is increased, the target material surface is prone to be oxidized; and when the oxygen content is decreased, the thin film is prone to be insufficiently oxidized.

[0053] The multilayer thin film thermocouple can be applied to a high-temperature measurement sensor or other high-temperature temperature measurement fields, and the high temperature in the application refers to a temperature higher than 900 DEG C.

[0054] High-temperature measurement: based on the Seebeck effect of materials, in the temperature measurement process, two different conductors A and B will form a thermoelectric potential difference in the loop due to the temperature difference between the cold end and the hot end. Generally, the greater the temperature difference, the higher the output potential. After calibrating the standard thermoelectric potential-temperature curve of the thermocouple, the corresponding temperature can be known by reading the thermoelectric potential value in the subsequent temperature measurement process.

[0055] The application has the following beneficial effects:

[0056] The multilayer thin film thermocouple in the application is a multilayer thin film structure, which comprises, from bottom to top, a bottom insulating layer, a bottom bonding layer, a functional material layer, a top bonding layer and a top insulating layer. In a high-temperature environment, the bonding layer with low stress is fused to cover the functional material layer, effectively reducing the stress interface of the functional material layer, thereby improving the stability. BRIEF DESCRIPTION OF DRAWINGS

[0057] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description only some embodiments of the application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0058] Figure 1 The structure of the multilayer thin film thermocouple of the application is shown.

[0059] 1-bottom insulating layer; 2-bottom bonding layer; 3-functional material layer; 4-top bonding layer; 5-top insulating layer;

[0060] Figure 2 The test results of the multilayer thin film thermocouple are shown.

[0061] Figure 3 The fusion of the functional layer at high temperature is shown.

[0062] Figure 4SEM image of a comparative example. DETAILED DESCRIPTION

[0063] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions of the present application will be described in detail below. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0064] As shown in Figure 1 The multilayer thin film thermocouple of the present application comprises, from bottom to top on the substrate, a bottom insulating layer 1, a bottom bonding layer 2, a functional material layer 3, a top bonding layer 4 and a top insulating layer 5, the functional material layer comprises a thermocouple function A end and a thermocouple function B end which are connected to each other, and the thermocouple function A end and the thermocouple function B end are connected by a pin, wherein,

[0065] The top bonding layer and the bottom bonding layer are selected to be materials with low stress, which can be fused with each other under high temperature conditions and coat the functional material layer, and the functional layer is coated by the bonding layer with low stress under high temperature, effectively reducing the stress interface of the functional layer and improving the stability.

[0066] The preparation method of the multilayer thin film thermocouple of the present application will be described below through specific embodiments.

[0067] Embodiment 1

[0068] The preparation method of the multilayer thin film thermocouple of the present application comprises the following steps:

[0069] (1) Bottom insulating barrier layer

[0070] The bottom insulating barrier layer is obtained by reactive magnetron sputtering on a cleaned alumina substrate (substrate surface roughness <400 nm), and the specific sputtering process parameters are as follows:

[0071] An aluminum target is used, the gas pressure is set to 2.0 Pa, the sputtering power is 150 W, the argon:oxygen ratio is 5:1, and the temperature is 300℃.

[0072] After sputtering, annealing is performed at 1050℃ for 30 min.

[0073] (2) Bottom bonding layer

[0074] The silicon-containing bonding layer is obtained by sputtering deposition, and the specific sputtering process parameters are as follows:

[0075] A silicon target is used, the gas pressure is set to 2.2 Pa, the sputtering power is 150 W, the sputtering atmosphere is argon:oxygen=5:1, and the temperature is 300℃

[0076] After sputtering, annealing at 1050°C for 60 min.

[0077] The adhesive layer covers the whole substrate with a thickness of 0.1-10.0 μm.

[0078] (3) Functional material layer

[0079] 3.1 Preparation of thermocouple functional A end by magnetron sputtering

[0080] The specific sputtering process parameters are: platinum target (purity > 4N), gas pressure 1.0 Pa, sputtering power 100 W, sputtering temperature 200°C. The thickness of the thin film is between 1 μm.

[0081] 3.2 Preparation of thermocouple functional B end by magnetron sputtering

[0082] The specific sputtering process parameters are: indium tin oxide target (purity > 4N, SnO2=5-30 wt%), gas pressure 1.0 Pa, sputtering power 60 W, sputtering temperature 300°C.

[0083] After sputtering, heat treatment is performed. The thickness of the thin film is between 3 μm.

[0084] (4) Top adhesive layer

[0085] The preparation method is the same as that of the bottom adhesive layer.

[0086] (5) Top insulating barrier layer

[0087] The preparation method is the same as that of the bottom insulating barrier layer.

[0088] Example 2

[0089] The multilayer thin film thermocouple obtained in Example 1 was tested. The testing method was carried out in a horizontal test furnace. After heating to 600°C, the signal of the thermocouple output was recorded. The temperature was continuously increased to 1200°C, then naturally cooled to 600°C, and then heated to 1200°C again. This was repeated. The 1200°C platform was the output signal recorded at 1200°C with constant temperature. The error and drift between signals were <1%.

[0090] Figure 2 The test results of the multilayer thin film thermocouple are shown.

[0091] Figure 3 The fusion between the SiO2 and Al2O3, SiO2 and SiO2 interfaces is shown.

[0092] Comparative Example

[0093] In this comparative example, during the preparation of the insulating layer, the argon:oxygen ratio was 9:1, and the other parameters were the same as in Example 1.

[0094] Results as shown in Figure 4 As the initial oxygen content is low, the subsequent annealing re-oxidation process is more intense, the atomic ratio Al:O = 1:1, the subsequent annealing ratio reaches 2:3, which leads to a more serious crystal structure change.

[0095] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited to this, any skilled person in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for preparing a multilayer thin film thermocouple suitable for high temperature cycle measurement, characterized in that: The preparation method comprises the following steps: (1) Sputtering a bottom insulating layer on the substrate; (2) sputtering a bottom bonding layer on the bottom insulating layer; (3) sputtering a thermocouple functional end A and a thermocouple functional end B on the bottom bonding layer, respectively, wherein the thermocouple functional end A and the thermocouple functional end B are connected to form a functional material layer; (4) sputtering a top bonding layer on the functional material layer; (5) sputtering a top insulating layer on the top bonding layer. After sputtering, annealing is performed at 500-1300°C. The top adhesive layer and the bottom adhesive layer can be fused with each other under high temperature conditions to cover the functional material layer; In step (2) and / or step (4), The sputtering parameters are: gas pressure of 1.5-2.5 Pa, sputtering power of 100-200 W; sputtering atmosphere is argon, oxygen or nitrogen; and / or, after sputtering, annealing at 300-1500° C.; And / or, the selected target material includes an aluminum target material, a silicon target material, a silicon carbide target material or a zirconium target material.

2. The method for preparing a multilayer thin film thermocouple suitable for high temperature cycle measurement according to claim 1, characterized in that: The materials of the bottom bonding layer and the top bonding layer are independently selected from aluminum target, silicon target, silicon carbide target or zirconium target.

3. The method for preparing a multilayer thin film thermocouple suitable for high temperature cycle measurement according to claim 1, characterized in that: The materials of the bottom insulating layer and the top insulating layer are independently selected from aluminum target, silicon target, silicon carbide target or zirconium target.

4. The method for preparing a multilayer thin film thermocouple suitable for high temperature cycle measurement according to claim 1, characterized in that: In step (1), The sputtering parameters are: gas pressure of 1.0-4.0 Pa, sputtering power of 20-200W; sputtering atmosphere is argon, oxygen or nitrogen; and / or, after sputtering, annealing at 500-1300° C.; And / or, the selected target material includes an aluminum target material, a silicon target material, a silicon carbide target material or a zirconium target material.

5. The method for preparing a multilayer thin film thermocouple suitable for high temperature cycle measurement according to claim 1, characterized in that: In step (5), The sputtering parameters are: gas pressure of 1.0-4.0 Pa, sputtering power of 20-200 W; sputtering atmosphere of argon, oxygen or nitrogen; and / or, The target materials of choice include aluminum, silicon, silicon carbide or zirconium.

6. The method for preparing a multilayer thin film thermocouple suitable for high temperature cycle measurement according to claim 1, characterized in that: In step (3), when preparing the thermocouple function A end, The material of the thermocouple functional end A is selected from indium tin oxide, constantan alloy, tungsten rhenium alloy or nickel chromium alloy; And / or, the sputtering parameters are: gas pressure of 0.5-3 Pa, sputtering power of 80-120 W, and sputtering temperature of 180-220° C.; And / or, the thickness of the functional end A of the prepared thermocouple is 1.0-4.0 μm; And / or, the purity of the indium tin oxide target is greater than 4N, and the content of SnO2 is 5-30wt%.

7. The method for preparing a multilayer thin film thermocouple suitable for high temperature cycle measurement according to claim 1, characterized in that: In step (3), when preparing the thermocouple function B end, The material of the thermocouple functional B end is selected from platinum, constantan alloy, tungsten-rhenium alloy or nickel-chromium alloy; and / or, the sputtering parameters are: gas pressure of 2-4 Pa, sputtering power of 50-150 W, and sputtering temperature of 250-350° C.; And / or, the thickness of the functional B end of the prepared thermocouple is 0.4-8 μm.

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