CN108007580A - High-temperature heat flux sensor based on SiC thermoelectric materials and preparation method thereof - Google Patents

Abstract

The present invention provides a high-temperature heat flow sensor based on SiC thermoelectric materials and a preparation method thereof, comprising: a SiC substrate having a first surface and a second surface, the first surface being provided with a groove and a platform area surrounded by the groove The composite dielectric film covers the groove and the platform area; the thermal insulation cavity is set in the SiC substrate, recessed from the second surface, and is located under the part of the composite dielectric film in the platform area; the P-type SiC thin film resistance block and N-type SiC thin film resistance block, located on the composite dielectric film in the platform area, and partially above the heat insulation cavity; insulating dielectric layer, covering P-type SiC thin film resistance block, N-type SiC thin film resistance block and composite dielectric film; metal pattern The layer is formed on the insulating medium layer, including electrodes and leads, and connects the P-type SiC thin-film resistance block and the N-type SiC thin-film resistance block to form a thermopile. The invention adopts single-crystal SiC with excellent high-temperature performance as a thermoelectric material, and can realize rapid and accurate measurement of heat flux density in a high-temperature harsh environment.

Description

High temperature heat flow sensor based on SiC thermoelectric material and its preparation method

technical field

The invention belongs to the technical field of heat flow detection, in particular to a high-temperature heat flow sensor based on SiC thermoelectric material and a preparation method thereof.

Background technique

In nature and in the production process, there are a lot of heat transfer problems. With the development of modern science and technology, it is far from enough to only use temperature as the only information for heat transfer. Therefore, more and more attention has been paid to the theory and technology of heat flow detection, and the corresponding heat flow sensors have also been greatly developed and widely used.

Although the existing heat flow sensors can meet the general measurement requirements of heat flux density in industrial and agricultural production and daily life, their heat resistance temperature and measurement range are generally low, usually below 1000°C and 1MW/m ² , and their size is relatively large. The response time is long, and the fastest is only on the order of ms. Therefore, in harsh environments with ultra-high temperature and high heat flow, such as aviation and aerospace engines, it is difficult for existing heat flow sensors to achieve fast and accurate measurement.

Thermopile heat flow devices manufactured using MEMS technology have unique advantages such as small size, simple structure, and fast response speed. However, facing the problems of ultra-high operating temperature and large heat flow, the selection of materials is particularly important. As a wide-bandgap semiconductor, SiC has high melting point, high thermal conductivity, high carrier mobility and high breakdown voltage, making it an ideal material for high-temperature sensing devices. At present, SiC-based high-temperature micro-heaters and flow sensors have been developed, but SiC-based high-temperature heat flow sensors have not been reported yet.

4H-SiC single crystal thin film material is a material with higher melting point and higher thermal conductivity in SiC. Using 4H-SiC thermoelectric material to manufacture large heat flow devices can make full use of its high temperature stability and high thermal conductivity. At the same time of thermal stability, rapid heating and cooling can be realized, so that its application in ultra-high temperature environment is possible.

Therefore, it is of great significance to develop a high-temperature heat flow sensor based on SiC thermoelectric materials with fast response and stable performance, regardless of industrial production requirements or technological development trends.

Contents of the invention

In view of the prior art described above, the purpose of the present invention is to provide a high-temperature heat flow sensor based on SiC thermoelectric material and its preparation method, which are used to realize rapid and accurate measurement of heat flux in high-temperature harsh environments such as aerospace and metallurgy.

In order to achieve the above purpose and other related purposes, the present invention provides a high temperature heat flow sensor based on SiC thermoelectric material, including:

a SiC substrate, the SiC substrate has a first surface and a second surface, a groove is provided on the first surface and a platform region is formed surrounded by the groove;

a composite dielectric film, located on the first surface of the SiC substrate, covering the surface of the groove and the surface of the platform region;

a heat-insulating cavity, provided in the SiC substrate, recessed inwardly from the second surface of the SiC substrate, and located under part of the composite dielectric film in the platform region;

The P-type SiC thin-film resistance block and the N-type SiC thin-film resistance block are located on the composite dielectric film at the position of the platform area, and are partially located above the heat-insulating cavity;

An insulating dielectric layer covering the P-type SiC thin-film resistor block and the N-type SiC thin-film resistor block and the composite dielectric film;

The metal layer is formed on the insulating medium layer, and includes electrodes and leads to connect the P-type SiC thin film resistance block and the N-type SiC thin film resistance block to form a thermopile.

Optionally, the material of the SiC substrate is selected from one of 4H-SiC, 6H-SiC, and 3C-SiC.

Optionally, the groove has a depth of 1-50 μm.

Optionally, the composite dielectric film is composed of single or multiple layers of silicon oxide and silicon nitride, with a thickness of 1-10 μm.

Optionally, the thermal insulation cavity penetrates through the SiC substrate, exposing part of the composite dielectric film; the thermal insulation cavity has a rectangular cross section.

Optionally, the material of the P-type SiC thin film resistance block and the N-type SiC thin film resistance block is selected from one of 4H-SiC, 6H-SiC, and 3C-SiC; the P-type SiC thin film resistance block and N The thickness of the type SiC thin film resistor block is less than 1 μm, and the thickness deviation does not exceed 3%.

Optionally, the material of the insulating dielectric layer includes one or both of silicon oxide and silicon nitride.

Optionally, the material of the metal layer is selected from one or more of titanium, tungsten and platinum.

In order to achieve the above purpose and other related purposes, the present invention also provides a method for preparing a high temperature heat flow sensor based on SiC thermoelectric material, comprising the following steps:

1) providing a SiC substrate having a first surface and a second surface, and etching a groove on the first surface to form a platform region surrounded by the groove;

2) forming a composite dielectric film on the first surface, the composite dielectric film covering the surface of the groove and the surface of the platform region;

3) forming a P-type SiC thin film resistance block and an N-type SiC thin film resistance block on the surface of the composite dielectric film in the platform area;

4) Form an insulating medium layer on the surface of the P-type SiC thin film resistance block and the N-type SiC thin film resistance block, and form a lead hole on the insulating medium layer to expose part of the P-type SiC thin film resistance block and the N-type SiC thin film resistance block. Type SiC thin film resistor block;

5) forming a metal layer including electrodes and leads on the surface of the insulating medium layer and the lead hole, so as to connect the P-type SiC thin film resistance block and the N-type SiC thin film resistance block into a thermopile;

6) Etching the second surface of the SiC substrate to form a heat-insulating cavity, the heat-insulating cavity is located under part of the composite dielectric film in the platform area, and makes the P-type SiC thin film resistance block and a part of the N-type SiC thin film resistance block is located above the heat-insulating cavity.

Optionally, in step 1), the material of the SiC substrate is selected from one of 4H-SiC, 6H-SiC, and 3C-SiC.

Optionally, in step 1), inductively coupled plasma etching (ICP) is used to form the groove by photoetching the window; the depth of the groove is 1-50 μm.

Optionally, in step 2), one or both methods of thermal oxidation and low pressure chemical vapor deposition (LPCVD) are used to form the composite dielectric film; Composite silicon and silicon nitride, the thickness is 1-10μm.

Optionally, in step 3), the method for forming the P-type SiC thin film resistor block and the N-type SiC thin film resistor block includes the following steps:

Transferring a layer of SiC thin film on the surface of the composite dielectric film;

performing P-type doping and N-type doping on the SiC thin film by using photoresist as a mask layer;

patterning the SiC film;

Annealing the patterned SiC thin film to form a P-type SiC thin-film resistor block and an N-type SiC thin-film resistor block.

Further optionally, the SiC thin film is transferred by means of ion beam stripping and substrate transfer; the material of the SiC thin film is selected from one of 4H-SiC, 6H-SiC, and 3C-SiC; the SiC thin film The thickness is less than 1μm, and the thickness deviation does not exceed 3%.

Further optionally, the SiC thin film is doped with P-type and N-type by ion implantation; and the SiC thin film is patterned by inductively coupled plasma etching (ICP).

Optionally, in step 4), the insulating dielectric layer is formed by plasma enhanced chemical vapor deposition (PECVD); the insulating dielectric layer includes one or both of silicon oxide and silicon nitride.

Optionally, in step 5), the metal layer is formed using a lift-of process or an electroplating process; the material of the metal layer is selected from one or more of titanium, tungsten, and gold.

Optionally, step 5) connect the P-type SiC thin-film resistance block and the N-type SiC thin-film resistance block into a thermopile structure composed of one thermocouple or multiple thermocouples connected in series.

Optionally, in step 6), inductively coupled plasma etching (ICP) is used to form the heat-insulating cavity to expose the composite dielectric film; the heat-insulating cavity has a rectangular cross section.

As mentioned above, the high-temperature heat flow sensor based on SiC thermoelectric material and its preparation method of the present invention have the following beneficial effects:

1. The present invention uses MEMS technology to manufacture heat flow devices, which have the unique advantages of small size and fast response speed. At the same time, it adopts a simple thermopile sensitive structure, the preparation process is simple, and the controllability is strong. It has a good comparison with the current mature semiconductor technology. compatibility;

2. The present invention reduces the temperature of the preparation process of the material through the ion beam stripping and transfer technology, which facilitates the preparation of SiC single crystal thin films. At the same time, the method also has the following two advantages: 1) The ion implanted stripped and transferred films have Single crystal quality of SiC bulk material; 2) SiC bulk single crystal can be cyclically peeled off the film, reducing material cost;

3. The present invention uses single crystal SiC with excellent high-temperature performance as a thermoelectric material to manufacture a P-SiC/N-SiC thermopile. Under the condition of satisfying high-temperature stability, a low-stress support film is established by using a semiconductor process to reduce the heat of the device. Capacitance, reduce the response time of the device, and increase the temperature difference between the hot end and the cold end of the thermopile at the same time, so as to realize the rapid and accurate measurement of the heat flux density in the environment of high temperature and large heat flow.

Description of drawings

Fig. 1 shows a schematic cross-sectional structure diagram of a high-temperature heat flow sensor based on SiC thermoelectric material provided by an embodiment of the present invention.

2a-2b show a schematic diagram of a three-dimensional structure of a SiC thermoelectric material-based high-temperature heat flow sensor provided for an embodiment of the present invention, wherein FIG. 2b is a layered schematic diagram of FIG. 2a.

3a-3b show a schematic perspective view of another high-temperature heat flow sensor based on SiC thermoelectric materials provided by an embodiment of the present invention, wherein FIG. 3b is a layered schematic diagram of FIG. 3a.

Fig. 4 shows a flowchart of a method for preparing a high-temperature heat flow sensor based on SiC thermoelectric materials provided by an embodiment of the present invention.

5a-5f show a schematic diagram of the fabrication process of a SiC thermoelectric material-based high-temperature heat flow sensor provided by an embodiment of the present invention.

Component designation description

10 SiC substrate

101 Groove

102 platform area

103 Insulation cavity

20 Composite dielectric film

30 SiC Thin Film Resistor Blocks

301 P-Type SiC Thin Film Resistor Block

302 N-Type SiC Thin Film Resistor Block

40 insulating dielectric layer

401 lead hole

50 metal layers

Steps from S1 to S6

Detailed ways

Embodiments of the present invention are described below through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation modes, and various modifications or changes can be made to the details in this specification based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, in the case of no conflict, the following embodiments and features in the embodiments can be combined with each other.

It should be noted that the diagrams provided in the following embodiments are only schematically illustrating the basic ideas of the present invention, and only the components related to the present invention are shown in the diagrams rather than the number, shape and shape of the components in actual implementation. Dimensional drawing, the type, quantity and proportion of each component can be changed arbitrarily during actual implementation, and the component layout type may also be more complicated.

Please refer to Fig. 1, the present embodiment provides a kind of high temperature heat flow sensor based on SiC thermoelectric material, including: SiC substrate 10, composite dielectric film 20, heat insulation cavity 103, SiC thin film resistance block 30, insulating dielectric layer 40, metal Layer 50.

The SiC substrate 10 has a first surface and a second surface, a groove 101 and a platform region 102 formed around the groove 101 are arranged on the first surface; the composite dielectric film 20 is located on the The first surface of the SiC substrate 10 covers the surface of the groove 101 and the surface of the platform region 102; The two surfaces are concave inward, and are located under the composite dielectric film 20 in the platform area 102; the SiC thin film resistance block 30 includes a P-type SiC thin film resistance block 301 and an N-type SiC thin film resistance block 302, as a thermoelectric Stack galvanic material; the SiC thin film resistance block 30 is located on the composite dielectric film 20 at the platform area 102, and is partially located above the heat insulation cavity 103; the insulating dielectric layer 40 covers the SiC thin film resistance block 30 and the surface of the composite dielectric film 20; the metal layer 50 is formed on the insulating dielectric layer 40, including electrodes and leads, so that the P-type SiC thin film resistance block 301 and the N-type The SiC thin film resistor blocks 302 are connected to form a thermopile.

Specifically, the material of the SiC substrate 10 includes but not limited to one of 4H-SiC, 6H-SiC, and 3C-SiC. In this embodiment, the material of the SiC substrate 10 is 4H-SiC.

Specifically, the depth of the groove 101 may be 1-50 μm, and in this embodiment, the depth of the groove 101 is 10 μm.

Specifically, the composite dielectric film 20 may be composed of a single layer or multiple layers of low-stress silicon oxide and silicon nitride, and the thickness may be 1-10 μm. In this embodiment, the composite dielectric film 20 is composed of four layers of low-stress silicon oxide/silicon nitride/silicon oxide/silicon nitride, with a thickness of 3.2 μm.

Specifically, the material of the SiC thin film resistor block 30 includes but is not limited to one of 4H-SiC, 6H-SiC, and 3C-SiC, the thickness is less than 1 μm, and the thickness deviation does not exceed 3%. In this embodiment, the SiC thin film resistor block 30 is made of a 4H-SiC thin film material with a thickness of 0.8 μm.

Specifically, the material of the insulating dielectric layer 40 includes one or both of silicon oxide and silicon nitride. In this embodiment, the insulating dielectric layer 40 is made of silicon nitride with a thickness of 0.1 μm.

Specifically, the material of the metal layer 50 is selected from metals with good electrical conductivity and relatively high melting point, including but not limited to one or more of titanium, tungsten, and platinum. In this embodiment, the metal layer 50 is titanium tungsten.

As a preferred solution of this embodiment, the thermal insulation cavity 103 may penetrate through the SiC substrate 10 to expose part of the composite dielectric film 20 to form a suspended film sensitive structure. Specifically, the heat insulation cavity 103 may have a rectangular cross section. In this embodiment, the heat insulating cavity 103 is a cylinder.

It should be noted that the P-type SiC thin film resistance block 301 and the N-type SiC thin film resistance block 302 are connected by metal leads to form a P-SiC/N-SiC thermocouple, and a plurality of P-SiC/N-SiC thermocouples are connected in series to form P-SiC/N-SiC thermopile structure, the number of the P-SiC/N-SiC thermocouple is at least 1, in this embodiment, the number of the P-SiC/N-SiC thermocouple is 2 or 5.

Figures 2a-2b and Figures 3a-3b respectively show the three-dimensional structures of two high-temperature heat flow sensors based on SiC thermoelectric materials provided in this embodiment with different numbers of thermocouples.

The high-temperature heat flow sensor based on SiC thermoelectric materials shown in Figures 2a-2b includes a SiC substrate 10, a composite dielectric film 20 on the SiC substrate 10, and two thermocouples connected by four SiC thin film resistance blocks 30, And two thermocouples are connected in series to form a thermopile structure. Among them, four SiC thin film resistor blocks 30 are arranged above the platform area 102 of the SiC substrate 10, evenly distributed, connected by leads 501, and electrodes 502 are arranged in the groove 101 (for ease of understanding, the insulating dielectric layer is omitted in the figure) . The outer contour of the platform area 102 adopts a rectangle. The heat-insulating cavity 103 is a cylinder, and is arranged in the center of the platform area 102 , so that a part of the SiC thin film resistor block 30 is located above the heat-insulating cavity 103 .

The high-temperature heat flow sensor based on SiC thermoelectric materials shown in Fig. 3a-3b includes 10 pieces of SiC thin-film resistance blocks 30 (that is, 5 pieces of P-type SiC thin-film resistance blocks 301 and 5 pieces of N-type SiC thin-film resistance blocks 302) connected. Five thermocouples, and the five thermocouples are connected in series to form a thermopile structure. Among them, 10 pieces of SiC thin film resistor blocks 30 are arranged above the platform area 102 of the SiC substrate 10, evenly distributed, connected by leads 501, and the electrodes 502 are arranged in the trenches 101 (for ease of understanding, the insulating medium layer is not shown in the figure) ). The outer contour of the platform area 102 is circular. The heat-insulating cavity 103 is a cylinder, and is arranged in the center of the platform area 102 , so that a part of the SiC thin film resistor block 30 is located above the heat-insulating cavity 103 .

The working principle of the above-mentioned high temperature heat flow sensor based on SiC thermoelectric material is: the suspended sensitive surface of the composite dielectric film 20 absorbs heat, and the heat flows rapidly along its radial direction to form a temperature gradient. The center of the suspended sensitive surface is set as the hot pole of the thermopile, and the SiC substrate 10 is regarded as the cold pole of the thermopile. In this way, the intensity of the incident heat flow can be directly measured by the output potential of the thermopile. In order to improve the heat absorption rate of the sensitive surface and ensure the sensitivity of the output signal, a black absorbing material can be coated on the surface of the sensitive surface, which can also fully absorb heat and improve the strength.

In addition, this embodiment also provides a method for preparing a high-temperature heat flow sensor based on SiC thermoelectric materials, as shown in FIG. 4 , including the following steps:

S1 providing a SiC substrate having a first surface and a second surface, and etching a trench on the first surface to form a platform region surrounded by the trench;

S2 forming a composite dielectric film on the first surface, the composite dielectric film covering the surface of the groove and the surface of the platform region;

S3 forming a P-type SiC thin-film resistor block and an N-type SiC thin-film resistor block on the surface of the composite dielectric film in the platform area;

S4 forms an insulating medium layer on the surface of the P-type SiC thin film resistor block and the N-type SiC thin film resistor block, and forms a lead hole on the insulating dielectric layer to expose part of the P-type SiC thin film resistor block and the N-type SiC thin film resistor block. SiC thin film resistor block;

S5 forming a metal layer including electrodes and leads on the surface of the insulating medium layer and the lead hole, so as to connect the P-type SiC thin film resistance block and the N-type SiC thin film resistance block into a thermopile;

S6 etches the second surface of the SiC substrate to form a heat-insulating cavity, the heat-insulating cavity is located under part of the composite dielectric film in the platform area, and makes the P-type SiC thin film resistor block and Part of the N-type SiC thin film resistance block is located above the heat-insulating cavity.

The above preparation method will be further described in detail below in conjunction with FIGS. 5a-5f.

First, as shown in FIG. 5a, step S1 is performed to provide a SiC substrate 10 having a first surface and a second surface (ie, a front surface and a back surface), and a photolithography process is used to perform a photolithography process on the first surface (front surface) of the substrate 10. ) forming an etching window, through which the SiC substrate 10 is etched to form a trench 101 with a predetermined depth, and a platform region 102 surrounded by the trench 101 .

Specifically, the material of the SiC substrate 10 includes but not limited to one of 4H-SiC, 6H-SiC, and 3C-SiC. In this embodiment, the material of the SiC substrate 10 is 4H-SiC.

Specifically, the etching window includes but is not limited to a rectangle or a circle, and the outer contour of the formed platform area 102 includes but not limited to a rectangle or a circle; in this embodiment, the resulting platform area The outer contour of 102 is rectangular (as shown in Figures 2a-2b) or circular (as shown in Figures 3a-3b).

Specifically, the trench 101 may be formed by inductively coupled plasma etching (ICP), and the depth of the trench 101 is 1-50 μm. In this embodiment, the depth of the trench 2 is 10 μm.

Then, as shown in FIG. 5b, step S2 is performed, and a composite dielectric film 20 is deposited on the surface of the SiC substrate 10 on which the trench 101 is formed, and the composite dielectric film 20 covers the surface of the trench 101 and the platform area. 102 surfaces. The composite dielectric film 20 can be composed of a single layer or multiple layers of silicon oxide and silicon nitride, with a thickness of 1-10 μm; in this embodiment, the composite dielectric film 20 is made of low-stress silicon oxide/silicon nitride /Silicon oxide/Silicon nitride four-layer film composite, the thickness is 3.2μm. The composite dielectric film 20 can be formed by thermal oxidation, low pressure chemical vapor deposition (LPCVD) and other methods.

Next, as shown in FIG. 5c, step S3 is executed to form a SiC thin film resistance block 30 as a thermopile couple material on the surface of the composite dielectric film 20, including a P-type SiC thin film resistance block 301 and an N-type SiC thin film resistance block. 302.

As a preferred solution of this embodiment, forming the P-type SiC thin film resistor block 301 and the N-type SiC thin film resistor block 302 may specifically include the following steps:

transfer a layer of SiC thin film on the surface of the composite dielectric film 20, form first and second windows successively on the surface of the SiC thin film through a photolithography process, and use the photoresist as a mask layer to process the SiC thin film Type and N-type doping, pattern the SiC thin film, and anneal to form a P-type SiC thin-film resistor block 301 and an N-type SiC thin-film resistor block 302 .

Wherein, the SiC thin film can be doped by ion implantation; the SiC thin film can be patterned by inductively coupled plasma etching (ICP); the SiC thin film can be transferred by ion beam stripping and substrate transfer. The material of the SiC thin film includes but is not limited to one of 4H-SiC, 6H-SiC, and 3C-SiC, the thickness is less than 1 μm, and the thickness deviation does not exceed 3%; in this embodiment, the SiC thin film adopts a thickness of 0.8 μm 4H-SiC.

It should be noted that the physical essence of the ion beam stripping and substrate transfer is to form bubbles and holes rich in implanted ions at a specific depth of the SiC single crystal by ion implantation of light elements such as H, and to form a stripping defect layer. During the heating process, the expansion of the injected gas detaches the surface SiC film from the single crystal substrate, and transfers the exfoliated SiC film to the SiC substrate through wafer bonding.

It should be noted that the ion beam stripping and substrate transfer technology can reduce the temperature of the material preparation process and facilitate the preparation of SiC thin films. At the same time, the thin films formed by this method have the single crystal quality of SiC bulk materials, and SiC Bulk single crystals can be cyclically stripped of thin films, reducing material costs.

Next, as shown in FIG. 5d, step S4 is performed to form an insulating dielectric layer 40 on the surface of the SiC thin film resistor block 30, and photolithography and etching the insulating dielectric layer 40 to expose part of the SiC thin film resistor block 30 , forming lead holes 401 . Specifically, the insulating dielectric layer 40 can be formed by plasma enhanced chemical vapor deposition (PECVD), and the insulating dielectric layer 40 includes one or both of silicon oxide and silicon nitride; in this embodiment, the The insulating dielectric layer 40 is made of silicon nitride with a thickness of 0.1 μm.

Then, as shown in FIG. 5e , step S5 is performed to deposit and pattern a layer of metal on the surface of the insulating dielectric layer 40 and the lead hole 401 as the lead 501 and the electrode 502 between the SiC thin film resistor blocks 30 , namely the metal layer 50 . The lead wire 501 connects the P-type SiC thin film resistance block and the N-type SiC thin film resistance block into one thermocouple or multiple thermocouples; the multiple thermocouples are connected in series to form a thermopile structure. In this embodiment, P- The number of SiC/N-SiC thermocouples is 2 or 5.

Specifically, the metal can be formed and patterned by using a lift-off process or an electroplating process. The metal needs to have good electrical conductivity and a high melting point at the same time, including but not limited to one or more of titanium, tungsten, and platinum. ; In this embodiment, the metal is formed and patterned by a lift-off process, and the metal is titanium tungsten.

Specifically, the steps of the stripping process are: glue spraying, photolithography to define the pattern of the metal lead 501 and the electrode 502, the thickness of the photoresist is 1-10 μm; sputtering titanium tungsten, the thickness is 0.2-2 μm; glue.

Finally, as shown in FIG. 5f, step S6 is performed to form a release window on the back side of the SiC substrate 10, and etch the SiC substrate 103 from the back side through the release window, and release to obtain a heat-insulating cavity 103, The preparation of the SiC high temperature heat flow sensor is completed.

Specifically, using inductively coupled plasma etching (ICP) to release the thermal insulation cavity 103, the thermal insulation cavity 103 penetrates the SiC substrate 10, exposes the composite dielectric film 20, and forms a suspended film sensitive structure , and has a rectangular cross section; in this embodiment, the heat insulating cavity 103 is a cylinder.

In summary, the high-temperature heat flow sensor based on SiC thermoelectric materials and its preparation method of the present invention adopt MEMS technology to manufacture heat flow devices, which have unique advantages such as small size and fast response speed. At the same time, a simple thermopile sensitive structure is adopted. It is simple, highly controllable, and has good compatibility with the current mature semiconductor technology; the temperature of the material preparation process is reduced by ion beam stripping and transfer technology, which facilitates the preparation of SiC single crystal thin films. At the same time, this method also It has the following two advantages: 1) the thin film transferred by ion implantation has the single crystal quality of SiC bulk material; 2) the SiC bulk single crystal can be cyclically peeled off the film, reducing material cost; the present invention uses single crystal SiC with excellent high temperature performance as Thermoelectric materials, manufacture P-SiC/N-SiC thermopile, under the condition of high temperature stability, use semiconductor technology to establish low-stress supporting film, reduce the heat capacity of the device, reduce the response time of the device, and increase the thermopile at the same time The temperature difference between the hot end and the cold end is conducive to the rapid and accurate measurement of the heat flux density in the environment of high temperature and large heat flow.

Therefore, the present invention effectively overcomes various shortcomings in the prior art and has high industrial application value.

The above-mentioned embodiments only illustrate the principles and effects of the present invention, but are not intended to limit the present invention. Anyone skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical ideas disclosed in the present invention should still be covered by the claims of the present invention.

Claims (19)

1. A high-temperature heat flow sensor based on SiC thermoelectric material, characterized in that, comprising: a SiC substrate, the SiC substrate has a first surface and a second surface, a groove is provided on the first surface and a platform region is formed surrounded by the groove; a composite dielectric film, located on the first surface of the SiC substrate, covering the surface of the groove and the surface of the platform region; a heat-insulating cavity, provided in the SiC substrate, recessed inwardly from the second surface of the SiC substrate, and located under part of the composite dielectric film in the platform region; The P-type SiC thin-film resistance block and the N-type SiC thin-film resistance block are located on the composite dielectric film at the position of the platform area, and are partially located above the heat-insulating cavity; An insulating dielectric layer covering the P-type SiC thin-film resistor block and the N-type SiC thin-film resistor block and the composite dielectric film; The metal layer is formed on the insulating medium layer, and includes electrodes and leads to connect the P-type SiC thin film resistance block and the N-type SiC thin film resistance block to form a thermopile. 2. The high-temperature heat flow sensor based on SiC thermoelectric material according to claim 1, characterized in that: the material of the SiC substrate is selected from one of 4H-SiC, 6H-SiC, and 3C-SiC. 3. The high-temperature heat flow sensor based on SiC thermoelectric material according to claim 1, characterized in that: the depth of the groove is 1-50 μm. 4 . The high-temperature heat flow sensor based on SiC thermoelectric material according to claim 1 , wherein the composite dielectric film is composed of single or multiple layers of silicon oxide and silicon nitride, with a thickness of 1-10 μm. 5. The high-temperature heat flow sensor based on SiC thermoelectric material according to claim 1, characterized in that: the heat-insulating cavity runs through the SiC substrate, exposing part of the composite dielectric film; the heat-insulating cavity Has a rectangular cross section. 6. The high-temperature heat flow sensor based on SiC thermoelectric material according to claim 1, characterized in that: the material of the P-type SiC thin film resistance block and the N-type SiC thin film resistance block is selected from 4H-SiC, 6H-SiC, One of 3C-SiC; the thickness of the P-type SiC thin-film resistor block and the N-type SiC thin-film resistor block is less than 1 μm, and the thickness deviation does not exceed 3%. 7. The high-temperature heat flow sensor based on SiC thermoelectric material according to claim 1, characterized in that: the material of the insulating dielectric layer includes one or both of silicon oxide and silicon nitride. 8. The high-temperature heat flow sensor based on SiC thermoelectric material according to claim 1, characterized in that: the material of the metal layer is selected from one or more of titanium, tungsten and platinum. 9. A method for preparing a high-temperature heat flow sensor based on SiC thermoelectric materials, characterized in that the method comprises the following steps: 1) providing a SiC substrate having a first surface and a second surface, and etching a groove on the first surface to form a platform region surrounded by the groove; 2) forming a composite dielectric film on the first surface, the composite dielectric film covering the surface of the groove and the surface of the platform region; 3) forming a P-type SiC thin film resistance block and an N-type SiC thin film resistance block on the surface of the composite dielectric film in the platform area; 4) Form an insulating medium layer on the surface of the P-type SiC thin film resistance block and the N-type SiC thin film resistance block, and form a lead hole on the insulating medium layer to expose part of the P-type SiC thin film resistance block and the N-type SiC thin film resistance block. Type SiC thin film resistor block; 5) forming a metal layer including electrodes and leads on the surface of the insulating medium layer and the lead hole, so as to connect the P-type SiC thin film resistance block and the N-type SiC thin film resistance block into a thermopile; 6) Etching the second surface of the SiC substrate to form a heat-insulating cavity, the heat-insulating cavity is located under part of the composite dielectric film in the platform area, and makes the P-type SiC thin film resistance block and a part of the N-type SiC thin film resistance block is located above the heat-insulating cavity. 10. the preparation method of the high-temperature heat flow sensor based on SiC thermoelectric material according to claim 9, is characterized in that: In step 1), the material of the SiC substrate is selected from one of 4H-SiC, 6H-SiC, and 3C-SiC. 11. the preparation method of the high-temperature heat flow sensor based on SiC thermoelectric material according to claim 9, is characterized in that: In step 1), the groove is formed through the photolithographic etching window by using inductively coupled plasma etching; the depth of the groove is 1-50 μm. 12. The method for preparing a high temperature heat flow sensor based on SiC thermoelectric material according to claim 9, characterized in that: In step 2), one or both of thermal oxidation and low pressure chemical vapor deposition are used to form the composite dielectric film; The composite dielectric film is composed of single or multiple layers of silicon oxide and silicon nitride, with a thickness of 1-10 μm. 13. The method for preparing a high-temperature heat flow sensor based on SiC thermoelectric materials according to claim 9, characterized in that: in step 3), the method for forming the P-type SiC thin film resistance block and the N-type SiC thin film resistance block comprises the following step: Transferring a layer of SiC film on the surface of the composite dielectric film; performing P-type doping and N-type doping on the SiC thin film by using photoresist as a mask layer; patterning the SiC film; Annealing the patterned SiC thin film to form a P-type SiC thin-film resistor block and an N-type SiC thin-film resistor block. 14. The method for preparing a high-temperature heat flow sensor based on SiC thermoelectric materials according to claim 13, characterized in that: the SiC thin film is transferred by means of ion beam stripping and substrate transfer; the material of the SiC thin film is selected from One of 4H-SiC, 6H-SiC, and 3C-SiC; the thickness of the SiC thin film is less than 1 μm, and the thickness deviation does not exceed 3%. 15. The method for preparing a high-temperature heat flow sensor based on SiC thermoelectric materials according to claim 13, characterized in that: P-type doping and N-type doping are performed on the SiC thin film by ion implantation; Bulk etching patterned the SiC thin film. 16. The method for preparing a high temperature heat flow sensor based on SiC thermoelectric material according to claim 9, characterized in that: In step 4), the insulating dielectric layer is formed by plasma enhanced chemical vapor deposition; the insulating dielectric layer includes one or both of silicon oxide and silicon nitride. 17. The method for preparing a high temperature heat flow sensor based on SiC thermoelectric material according to claim 9, characterized in that: In step 5), the metal layer is formed by using a stripping process or an electroplating process; the material of the metal layer is selected from one or more of titanium, tungsten, and platinum. 18. The method for preparing a high temperature heat flow sensor based on SiC thermoelectric material according to claim 9, characterized in that: Step 5) Connecting the P-type SiC thin-film resistance block and the N-type SiC thin-film resistance block into one thermocouple or a thermopile structure in which multiple thermocouples are connected in series. 19. The method for preparing a high temperature heat flow sensor based on SiC thermoelectric material according to claim 9, characterized in that: In step 6), the heat-insulating cavity is formed by inductively coupled plasma etching to expose the composite dielectric film; the heat-insulating cavity has a rectangular cross section.