CN110655032B

CN110655032B - Ceramic-based micro-hotplate with functional layer and preparation method thereof

Info

Publication number: CN110655032B
Application number: CN201810879807.5A
Authority: CN
Inventors: 王锦; 张克栋; 周乾飞; 冯奇; 崔铮; 李智星; 刘福星
Original assignee: Suzhou Nanogrid Technology Co ltd; SAIC Motor Corp Ltd
Current assignee: Suzhou Nanogrid Technology Co ltd; SAIC Motor Corp Ltd
Priority date: 2018-06-29
Filing date: 2018-08-03
Publication date: 2022-12-23
Anticipated expiration: 2038-08-03
Also published as: CN110655032A

Abstract

The invention discloses a ceramic-based micro-heating plate with a functional layer and a preparation method thereof. The ceramic membrane and the heating layer are formed by a high-temperature sintering process, so that the ceramic membrane and the heating layer have better high-temperature resistance, and compared with the prior art in which the heating layer is formed by physical vapor deposition under a low-temperature process condition, the heating layer formed by the high-temperature sintering process has better high-temperature resistance, so that the stability and the reliability can be improved, the equipment cost is lower, and the manufacturing cost is reduced. An insulating medium layer is arranged between the functional layer and the heating layer, so that the problem of mutual interference of heating signals and sensing signals is avoided.

Description

Ceramic-based micro-hotplate with functional layer and preparation method thereof

The present application claims priority of chinese patent application having application number 201810715807.1 entitled "a silicon-based ceramic substrate and method for making the same" filed by the chinese patent office on 29/06/29/2018, the entire contents of which are incorporated herein by reference.

Technical Field

The invention relates to the technical field of electronic device manufacturing, in particular to a ceramic-based micro-hotplate with a functional layer and a preparation method thereof.

Background

Micro Hot Plate (MHP) based on silicon Micro machining technology is a common heating platform in Micro Electro Mechanical Systems (MEMS), and has been widely applied to Micro devices such as Micro gas sensors, micro thermal flow meters, micro infrared detectors, barometers, and the like. The basic structure of the micro-hotplate comprises an overhead dielectric film and a resistor strip. When current is passed through the resistive track, a portion of the joule heating generated by the resistor is used to heat the micro-hotplate, and another portion is dissipated in the ambient environment by conduction, convection, and radiation. The suspended structure makes the micro-heating plate have very small thermal inertia and very high electric-thermal coupling efficiency, and the central temperature zone of the micro-heating plate can be rapidly heated within a few milliseconds due to milliwatt-level thermal power. Thus, the micro-hotplate has a very fast thermal response time and low thermal power consumption.

The processing technology of the silicon-based micro-heating plate prepared based on the MEMS technology mainly comprises three processing technologies of back bulk silicon, front bulk silicon and surface, the main technological process is to deposit a silicon nitride film and a silicon oxide film with certain thickness on a silicon wafer by adopting a chemical vapor deposition technology, prepare a patterned resistance heating film by adopting a physical vapor deposition technology, and then etch silicon below the silicon nitride film and the silicon oxide film by adopting a deep silicon etching technology, so that the silicon nitride film and the silicon oxide film are suspended, and the micro-heating plate with good heat insulation performance is obtained. However, the resistance heating film prepared by physical vapor deposition of the existing micro-hotplate is usually platinum, tungsten, molybdenum or polysilicon with a thickness of hundreds of nanometers, and the thickness of the material is small, so that the formed film crystal grain is small, when the material is subjected to high-temperature heat treatment (above 600 ℃), the heating resistance is usually irreversibly changed, and after the high-temperature treatment, a gold wire ball-bonding process cannot be carried out due to surface oxidation, or the resistance is changed when the material is heated to a certain high temperature (above 600 ℃), for example, a semiconductor gas sensor based on a silicon-based micro-hotplate, when a tin dioxide semiconductor material is deposited on the surface of the sensor, annealing at 600 ℃ in an air atmosphere is required, and if the micro-hotplate cannot bear the temperature, the semiconductor gas sensor based on the silicon-based micro-hotplate cannot complete preparation of a good gas-sensitive material. Secondly, the adopted silicon dioxide material still has higher thermal conductivity (7W/m.K), which is not beneficial to further reducing the power consumption of the micro-hotplate. Moreover, the silicon nitride film, the silicon dioxide film and the resistance heating film are all prepared by adopting a chemical or physical vapor deposition process, the required equipment is expensive, the preparation process cost is high, and the cost of the micro-hotplate is not favorably reduced further.

When the micro-hotplate is used in the fields of gas concentration detection, infrared detection and the like, corresponding signal sensing materials need to be prepared on the micro-hotplate, and corresponding signal sensing electrodes need to be prepared. If the signal sensing material is deposited on the heating electrode, the heating electrode and the signal sensing material are in physical contact, which is easy to cause mutual influence between the heating electrode and the signal sensing material, and the final test result is inaccurate.

As can be seen from the above description, in the prior art, the micro-hotplate mainly has the following problems that the resistance heating film formed by physical vapor deposition has poor high temperature resistance, resulting in poor stability and reliability of the product; moreover, the silicon dioxide film has high thermal conductivity, and as the heat dissipation is fast, in order to maintain the set working temperature, large input power is required, which is not beneficial to further reducing the power consumption of the micro-hotplate; meanwhile, physical vapor deposition equipment and chemical vapor deposition equipment are expensive, so that the manufacturing cost of the silicon nitride film, the silicon dioxide film and the resistance heating film is high, and the cost of the micro-hotplate is not further reduced; further, when a functional layer for sensing an external signal is formed on the micro-hotplate, a general micro-hotplate easily causes mutual interference of a heating signal and a sensing signal.

Disclosure of Invention

In order to solve the problems, the technical scheme of the invention provides the ceramic-based micro-hotplate with the functional layer, which has the advantages of good stability and reliability, simple manufacturing process, low manufacturing cost, low heating power consumption and capability of avoiding the mutual interference between the heating signal and the sensing signal.

In order to achieve the above purpose, the invention provides the following technical scheme:

a ceramic-based micro-hotplate with a functional layer, the ceramic-based micro-hotplate comprising:

a silicon substrate having opposing first and second surfaces; the first surface having a central heating zone with an air insulating cavity extending through the first surface and the second surface and a peripheral support zone;

a ceramic film disposed on a first surface of the silicon substrate;

the heating layer is arranged on the surface of one side, away from the silicon substrate, of the ceramic film; the heating layer comprises a heating electrode and a heating resistor which are electrically connected; the heating resistor is positioned in the central heating area;

the insulating medium layer is arranged on one side, away from the silicon substrate, of the heating layer;

the functional layer is arranged on one side, away from the heating layer, of the insulating medium layer and comprises a signal sensing electrode and a functional module which are electrically connected with each other, and the functional module is used for sensing an external signal;

the ceramic film is formed by sintering set ceramic slurry formed on the surface of the silicon substrate; the heating layer is formed by sintering set conductive slurry formed on the surface of the ceramic membrane.

Preferably, in the ceramic-based micro-hotplate, the silicon substrate is a monocrystalline silicon wafer with double-sided oxidation, single-sided oxidation or unoxidized structure, and the crystal orientation of the monocrystalline silicon wafer is 100 or 111;

or the silicon substrate is a polycrystalline silicon wafer with double-sided oxidation, single-sided oxidation or unoxidized silicon substrate.

Preferably, in the ceramic-based micro-hotplate, the silicon substrate has a thickness of 50-700 μm, inclusive.

Preferably, in the ceramic-based micro-hotplate, the ceramic slurry is a mixed material of glass and a ceramic system;

or, the ceramic slurry is a microcrystalline glass system;

or, the ceramic slurry is a single phase ceramic.

Preferably, in the ceramic-based micro-hotplate, the ceramic membrane has a thickness of 1 μm to 50 μm, inclusive.

Preferably, in the ceramic-based micro-hotplate, the ceramic film has a resistivity greater than 10 ¹³ Ω·cm。

Preferably, in the ceramic-based micro-hotplate, the ceramic membrane has a coefficient of thermal expansion of 0.5 × 10 ^-6 /℃-10×10 ^-6 /° c, inclusive.

Preferably, in the ceramic-based micro-hotplate, the ceramic membrane has a dielectric constant of 3 to 10, inclusive.

Preferably, in the ceramic-based micro-hotplate, the ceramic membrane has a thermal conductivity of 0.5W/(m.K) -10W/(m.K), inclusive.

Preferably, in the ceramic-based micro-hotplate, the ceramic membrane has a stress of 100MPa to 1000MPa, inclusive.

Preferably, in the ceramic-based micro-hotplate, the ceramic membrane is polished such that the roughness of the ceramic membrane is between 0.5nm and 1 μm, inclusive.

Preferably, in the ceramic-based micro-hotplate, the ceramic membrane covers the first surface completely or covers a part of the first surface.

Preferably, in the ceramic-based micro-hotplate, the ceramic-based micro-hotplate comprises a plurality of ceramic films, wherein the ceramic films have different ceramic slurries and different thicknesses.

Preferably, in the ceramic-based micro-hotplate, when the ceramic slurry is a mixed material of glass and a ceramic system, the ceramic phase material in the ceramic slurry includes one or more of alumina ceramic, magnesia ceramic, beryllia ceramic, zirconia ceramic, aluminum nitride ceramic, silicon nitride ceramic, boron nitride ceramic, titanium nitride ceramic, silicon carbide ceramic, titanium carbide ceramic and boron carbide ceramic, the glass phase material is an amorphous solid with a random structure prepared by adding a plurality of inorganic minerals as main raw materials and auxiliary raw materials, and crystal grains of the ceramic phase material are fused into an amorphous grid of the glass phase material to form the ceramic membrane.

Preferably, in the ceramic-based micro-hotplate, when the ceramic slurry is a microcrystalline glass system, the microcrystalline glass in the ceramic slurry is a solid composite material which is formed by heating base glass and contains a crystal orientation and a glass phase;

wherein the base glass comprises a multi-component oxide, and under a set condition, a part of the base glass forms a regular arrangement and forms a microcrystalline glass phase in the glass phase.

Preferably, in the ceramic-based micro-hotplate, the base glass comprises one or more of silicate glass, aluminosilicate glass, borate glass, borosilicate glass, fluorosilicate glass, phosphosilicate glass.

Preferably, in the ceramic-based micro-hotplate, the microcrystalline glass phase in the ceramic slurry comprises MgO — Al ₂ O ₃ -SiO ₂ Cordierite system, li ₂ O-Al ₂ O ₃ -SiO ₂ Spodumene system, li ₂ O-ZnO-Al ₂ O ₃ -SiO ₂ Spodumene system, baO-Al ₂ O ₃ -SiO ₂ Barium feldspar system, baO-Al ₂ O ₃ -SiO ₂ -TiO ₂ Celsian system, caO-Al ₂ O ₃ -SiO ₂ Anorthite system, caO-B ₂ O ₃ -SiO ₂ Calborosilicate glass System, li ₂ O-ZnO-MgO-Al ₂ O ₃ -SiO ₂ Beta-quartz system, F-K ₂ O-Na ₂ O-CaO-SiO ₂ Wollastonite system, F-X-MgO-SiO ₂ Fluoroamphibole system, F-X-MgO-Al ₂ O ₃ -SiO ₂ Fluoromica System, P ₂ O ₅ -Li ₂ O-SiO ₂ Any one or more of the lithium silicate systems.

Preferably, in the ceramic-based micro-hotplate, when the ceramic slurry is a single-phase ceramic, the single-phase ceramic in the ceramic slurry is a barium tin borate ceramic or a barium zirconium borate ceramic.

Preferably, in the ceramic-based micro-hotplate, the thickness of the heating electrode is 0.5um to 50um inclusive;

the heating electrode is made of any one of Pt, au, ag, cu, al, ni, W, ag/Pd alloy and Pt/Au alloy.

Preferably, in the ceramic-based micro-hotplate, the heating resistor has a thickness of 0.5um to 50um inclusive;

the heating resistor is a resistor wire with a preset shape formed by patterning the conductive film layer;

the heating resistor is made of any one of Pt, au, ag, cu, al, ni, W, mo, ni/Cr alloy, mo/Mn alloy, cu/Zn alloy, ag/Pd alloy, pt/Au alloy, fe/Co alloy, ruO2 and SnO2: sb2O 3.

Preferably, in the ceramic-based micro-hotplate, the thickness of the insulating medium layer is 1 um-10 um.

Preferably, in the ceramic-based micro-hotplate, the resistivity of the insulating dielectric layer is greater than 10 ¹³ Ω·cm。

The invention also provides a preparation method of the ceramic-based micro-hotplate, which is used for preparing any one ceramic-based micro hotplate, and is characterized by comprising the following steps:

providing a silicon substrate, wherein the silicon substrate is provided with a first surface and a second surface which are opposite; the first surface has a central heating zone and a peripheral support zone;

forming a film layer of set ceramic slurry on the first surface;

forming a ceramic film attached to the first surface through drying and sintering processes in sequence;

forming a conductive film layer with set conductive slurry on the surface of the ceramic film;

forming a heating layer attached to the surface of the ceramic membrane through drying and sintering processes in sequence;

forming an insulating medium layer on the surface of the heating layer;

forming a functional layer on the surface of the insulating medium layer, wherein the functional layer comprises a signal sensing electrode and a functional module which are electrically connected with each other, and the functional module is used for sensing an external signal;

and etching the second surface to form an air heat insulation cavity penetrating through the first surface and the second surface corresponding to the central heating area.

Preferably, in the above preparation method, the process temperature during drying is 40 ℃ to 200 ℃, inclusive;

the process temperature during sintering is 500 ℃ to 1400 ℃, inclusive.

Preferably, in the above manufacturing method, the forming of the insulating medium layer on the surface of the heating layer includes:

forming a film layer of set slurry on the surface of the heating layer;

and sequentially drying and sintering the film layer to form the insulating medium layer.

Preferably, in the above manufacturing method, the forming a functional layer on the surface of the insulating medium layer includes:

respectively printing the slurry of the signal sensing electrode and the slurry of the functional module on the insulating medium layer by a screen printing process;

and drying and sintering in sequence to form the signal sensing electrode and the functional module which are attached to the surface of the insulating medium layer.

According to the ceramic-based micro-hotplate with the functional layer and the preparation method thereof, the ceramic membrane and the heating layer are sequentially formed on the first surface of the silicon substrate, the ceramic membrane is formed by sintering the set ceramic slurry, the heating layer is formed by sintering the set conductive slurry, the insulating dielectric layer is formed on the surface of the heating layer, and the functional layer is formed on the surface of the insulating dielectric layer.

Therefore, the ceramic membrane and the heating layer are formed by a high-temperature sintering process and have better high-temperature resistance, so that compared with the prior art that the heating layer is formed by physical vapor deposition under low-temperature process conditions, the heating layer formed by the high-temperature sintering process has better high-temperature resistance, and the stability and the reliability can be improved. And the heat conductivity of the ceramic membrane can be adjusted by adjusting the composition of the ceramic slurry, so that the problem of rapid heat dissipation is avoided, and the heating power consumption is reduced. Meanwhile, the equipment for forming the ceramic membrane and the heating layer by sintering the corresponding slurry is lower in equipment cost and lower in manufacturing cost compared with chemical vapor deposition and physical vapor deposition equipment. And an insulating medium layer is arranged between the functional layer and the heating layer, so that the problem of mutual interference of heating signals and sensing signals is avoided.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the prior art descriptions will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

FIG. 1 is a schematic structural diagram of a ceramic-based micro-hotplate with functional layers according to an embodiment of the present invention;

fig. 2 is a top view of a ceramic film on the surface of a ceramic film micro-hotplate according to an embodiment of the present invention;

fig. 3 is a top view of a functional layer on the surface of a ceramic membrane micro-hotplate according to an embodiment of the present invention;

FIG. 4 is a schematic structural diagram of another ceramic membrane micro-hotplate with functional layers according to an embodiment of the present invention;

fig. 5 is a schematic structural diagram of a heating layer according to an embodiment of the present invention;

FIG. 6 is a schematic flow chart of a preparation method provided by an embodiment of the invention;

FIG. 7 is a top view of a ceramic-based micro-hotplate according to an embodiment of the invention;

fig. 8 is a schematic flow chart of another preparation method provided in the embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

As described in the prior art, in the conventional micro-hotplate, a silicon nitride film and a silicon dioxide film are sequentially formed on one side surface of a silicon wafer substrate by chemical vapor deposition, and then a resistance heating film is formed on the silicon dioxide surface by physical vapor deposition.

The physical vapor deposition process has low temperature, the formed resistance heating film has poor high temperature resistance, the micro-hot plate has high temperature in the subsequent gold wire ball bonding process or as a catalytic combustion gas sensor, and the poor high temperature resistance of the resistance heating film can cause poor reliability and stability of products and influence the product quality.

And the silicon dioxide has higher thermal conductivity, which can lead to higher heat dissipation speed, so that when the micro-hotplate is used for heating operation, such as a catalytic combustion sensor, the micro-hotplate needs to be heated to a gas combustion temperature, higher power consumption is needed to overcome the heat consumption caused by the higher heat dissipation speed, and the power consumption is higher when the product operates.

Meanwhile, the physical vapor deposition equipment and the chemical vapor deposition equipment are expensive, so that the preparation cost of the product is high.

The inventor researches and discovers that if the mature processing technology of the silicon substrate is combined with the excellent electrical, mechanical and thermal properties of the ceramic substrate, the ceramic film prepared on the silicon substrate can meet the requirements of specific products. That is, the ceramic film is formed on the silicon substrate by the set ceramic slurry, so that the ceramic substrate with better electrical, mechanical and thermal properties can be formed, and the manufacturing cost is lower. Then, a high-temperature resistant heating layer is formed on the surface of the ceramic substrate by sintering the conductive paste, so that the reliability and stability of the product are improved, and the manufacturing cost can be greatly reduced. And an insulating medium layer can be formed on the surface of the heating layer, and a functional layer is formed on the surface of the insulating medium layer, so that the problem of mutual interference of the heating signal and the sensing signal can be avoided.

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.

Referring to fig. 1, fig. 1 is a schematic structural diagram of a ceramic-based micro-hotplate with a functional layer according to an embodiment of the present invention, where the ceramic-based micro-hotplate 10 includes: a silicon substrate 11, the silicon substrate 11 having a first surface 111 and a second surface 112 opposite to each other; the first surface has a central heating zone a with an air insulating cavity 15 running through the first and second surfaces and a peripheral support zone B; a ceramic film 12 disposed on a first surface of the silicon substrate 11; the heating layer is arranged on the surface of one side, away from the silicon substrate 11, of the ceramic membrane 12; the heating layer comprises a heating electrode 13 and a heating resistor 14 which are electrically connected; the heating resistor 14 is located in the central heating area a.

The heating electrode 13 and the heating resistor 14 may be prepared using the same heating layer formed of the same conductive paste. In other manners, the two may be prepared by using different resistance pastes and electrode pastes, at this time, the heating electrode 13 is a conductive pad with a certain area, and an external circuit may be electrically connected to the heating electrode 13 by welding manners such as pressure welding, ball welding, spot welding, and the like. The heating electrode 13 mainly provides the signal of telecommunication that the external world applyed for the micro-hotplate, and heating resistor 14 is the main heating element of micro-hotplate, and when external electric current transmitted heating resistor through the heating electrode, heating resistor produced joule heat, and then provided the heat source for the micro-hotplate.

In order to make the micro-hotplate have smaller heat capacity and faster thermal response, the ceramic membrane in contact with the heating resistor is set as a suspended membrane, and silicon in contact with the ceramic membrane and the substrate 11 is completely etched by an etching technology to form the air heat-insulating cavity 15. An air heat insulation cavity 15 is formed by adopting a deep silicon etching technology, and the silicon substrate 11 corresponding to the central heating area A can be etched by a physical method or a chemical method to form the air heat insulation cavity. The shape of the heating resistor 14 is properly adjusted according to different shapes of the heating layer, however, no matter what the shape is, the heating electrode 13 and the heating resistor 14 are electrically connected, the heating resistor 14 is set to be a specific shape according to requirements, and a specific temperature is provided for the operation of the micro-heating plate after heating.

Wherein, the ceramic film 12 is formed by sintering a set ceramic slurry formed on the surface of the silicon substrate 11; the heating layer is formed by sintering a set conductive paste formed on the surface of the ceramic membrane 12. The heating electrode 13 is used for acquiring an electric signal input by an external circuit to provide an operating voltage for the heating resistor.

The ceramic film 12 is formed on the surface of the silicon substrate 11 by adopting the set ceramic slurry through a thick film printing process, and after high-temperature sintering, the dense ceramic film 12 can be formed, so that the ceramic film 12 can be stably and reliably combined with the silicon substrate 11, the bonding force is good, and the ceramic film is dense and hard.

The micro-hotplate further comprises an insulating medium layer 16 arranged on one side, away from the silicon substrate 11, of the heating layer; and the functional layer is arranged on one side, away from the heating layer, of the insulating medium layer 16 and comprises a signal sensing electrode 17 and a functional module 18 which are electrically connected with each other, and the functional module 18 is used for sensing an external signal. The sensing electrode 17 and the heating resistor 14 are isolated by the insulating medium layer 16, so that mutual interference between different electric signals is avoided. The functional layer 18 may be made of a material that is selectively set according to the function to be achieved by the micro-hotplate.

Compared with the prior art, the ceramic membrane 12 and the heating layer of the ceramic-based micro-hotplate 10 are prepared by respectively forming a membrane by using set slurry and sintering at a high temperature. And through high temperature heat treatment or heating to certain high temperature, zone of heating and ceramic membrane 12 all have better high temperature resistant characteristic, and the resistance of the heating resistor 14 of zone of heating is stable, and the product robustness is better. The ceramic film 12 has lower thermal conductivity and better heat insulation performance, and is beneficial to further reducing the power consumption of the ceramic-based micro-hotplate 10. Moreover, the ceramic film 12 and the heating layer can be formed by a thick film printing technology, expensive physical vapor deposition or chemical vapor deposition equipment is not adopted, and a low-cost film forming process is adopted, so that the product cost is reduced.

The silicon substrate 11 is a single crystal silicon wafer with double-sided oxidation, single-sided oxidation or non-oxidation, and the crystal orientation of the single crystal silicon wafer is 100 or 111, so that the ceramic film 12 and the silicon substrate 11 have a stable contact effect. Or the silicon substrate is a polycrystalline silicon wafer with double-sided oxidation, single-sided oxidation or unoxidized silicon substrate. By using a monocrystalline silicon wafer or a polycrystalline silicon wafer, the ceramic film 12 and the silicon substrate 11 can have a stable contact effect.

The thickness of the silicon substrate 11 is 50 μm to 700 μm, inclusive. Specifically, the thickness of the silicon substrate 11 may be 100 μm, 200 μm, 300 μm, 50 μm, or 600 μm. By adopting the silicon substrate 11 with the thickness value, the ceramic film micro-heating plate 10 has better mechanical strength while ensuring that the ceramic film micro-heating plate 10 has thinner thickness.

In the embodiment of the application, the ceramic slurry can be a mixed material of glass and a ceramic system; alternatively, the ceramic slurry may be a microcrystalline glass system; alternatively, the ceramic slurry may be a single phase ceramic.

When the ceramic slurry is a mixed material of glass and a ceramic system, the ceramic slurry comprises two crystal phases, namely a glass phase and a ceramic phase. Wherein the ceramic phase material comprises one or more of alumina ceramic, magnesia ceramic, beryllium oxide ceramic, zirconia ceramic, aluminum nitride ceramic, silicon nitride ceramic, boron nitride ceramic, titanium nitride ceramic, silicon carbide ceramic, titanium carbide ceramic and boron carbide ceramic; the glass phase material is an amorphous solid with a random structure, which is prepared by taking a plurality of inorganic minerals (comprising one or more of quartz sand, borax, boric acid, barite, barium carbonate, limestone, potassium feldspar, albite, sodium carbonate, zinc oxide, bismuth oxide, lead oxide, copper oxide, chromium oxide and the like) as main raw materials and adding auxiliary raw materials, and has an amorphous grid structure. A small amount of auxiliary raw materials are added into the main raw materials, and the proportion of the main raw materials and the auxiliary raw materials can be set according to requirements. Under high temperature conditions, the grains of the ceramic phase material are fused into the amorphous lattice of the glass phase material to form the ceramic film.

When the ceramic slurry is a microcrystalline glass system, in the ceramic slurry, microcrystalline glass is a solid composite material which is formed by heating base glass and contains crystal orientation and a glass phase. Wherein the base glass comprises a multi-component oxide, and under a set condition, a part of the base glass forms a regular arrangement and forms a microcrystalline glass phase in the glass phase. Specifically, the base glass comprises one or more of silicate glass, aluminosilicate glass, borate glass, borosilicate glass, fluorosilicate glass and phosphosilicate glass.

When the ceramic slurry is a microcrystalline glass system, the crystal orientation of the ceramic slurry has a microcrystalline glass phase, optionally, the microcrystalline glass phase comprises MgO-Al ₂ O ₃ -SiO ₂ Cordierite system, li ₂ O-Al ₂ O ₃ -SiO ₂ Spodumene system, li ₂ O-ZnO-Al ₂ O ₃ -SiO ₂ Spodumene system, baO-Al ₂ O ₃ -SiO ₂ Bafeldspar system, baO-Al ₂ O ₃ -SiO ₂ -TiO ₂ Celsian system, caO-Al ₂ O ₃ -SiO ₂ Anorthite system, caO-B ₂ O ₃ -SiO ₂ Calborosilicate glass System, li ₂ O-ZnO-MgO-Al ₂ O ₃ -SiO ₂ Beta quartz system, F-K ₂ O-Na ₂ O-CaO-SiO ₂ Wollastonite system, F-X-MgO-SiO ₂ Fluoroamphibole system (X is oxide of Li, na, K, ca, etc.), F-X-MgO-Al ₂ O ₃ -SiO ₂ Fluoromica system (X is alkali metal or alkaline earth metal oxide), P ₂ O ₅ -Li ₂ O-SiO ₂ Any one or more of the lithium silicate systems.

When the ceramic slurry is single-phase ceramic, the single-phase ceramic in the ceramic slurry is barium tin borate ceramic or barium zirconium borate ceramic.

The ceramic film 12 may have a thickness of 1 μm to 50 μm, inclusive. Specifically, the thickness of the ceramic film 12 may be 10 μm, 20 μm, 30 μm, or 40 μm. The ceramic film 12 with the thickness value is formed on the surface of the silicon substrate 11, so that the ceramic film 12 has better electrical, mechanical and thermal properties while the ceramic film 12 is ensured to be thinner.

The ceramic film 12 has a resistivity greater than 10 ¹³ Omega cm. The silicon-based ceramic film 10 according to the embodiment of the present invention has a relatively large resistivity and a good insulating property.

The ceramic film 12 has a coefficient of thermal expansion of 0.5X 10 ^-6 /℃-10×10 ^-6 /° c, inclusive. Specifically, the ceramic film 12 may have a thermal expansion coefficient of 1 × 10 ^-6 /℃、4×10 ^-6 /℃、6×10 ^-6 /° C or 8 × 10 ^-6 /. Degree.C.. The ceramic film 12 with the thermal expansion coefficient value is formed on the surface of the silicon substrate 11, so that the thermal expansion coefficient of the ceramic film 12 is matched with that of the silicon substrate 11, the problems of ceramic film tilting or cracking and the like caused by different thermal expansion degree amplitudes of the ceramic film 12 and the silicon substrate 11 due to temperature changes can be avoided, and the reliability and stability of the ceramic film micro-heating plate 10 are ensured.

The dielectric constant of the ceramic film 12 is between 3 and 10 inclusive. Specifically, the dielectric constant of the ceramic film 12 may be 4, 5, 6, 7, or 9. The ceramic film 12 having the dielectric constant value described above is formed on the surface of the silicon substrate 11, so that the ceramic film 12 has excellent electrical characteristics.

The ceramic film 12 has a thermal conductivity of 0.5W/(m.K) -10W/(m.K), inclusive. Specifically, the thermal conductivity of the ceramic film 12 is 2W/(m · K), 4W/(m · K), 6W/(m · K), or 8W/(m · K). The ceramic film 12 with the thermal conductivity value is formed on the surface of the silicon substrate 11, so that the ceramic film 12 has excellent thermal characteristics and moderate heat conduction speed. Like this, when this ceramic membrane micro-heating plate 10 is used for the micro-heating plate of catalytic combustion sensor, because the catalytic combustion sensor need carry out gas detection under the best operating temperature of catalyst, this application technical scheme can avoid because the catalyst activity that the heat dissipation leads to too fast is relatively poor, need carry out the problem of heat compensation through the increase current, can avoid the slow problem that leads to the temperature to exceed the best operating temperature of catalyst of heat dissipation simultaneously, it is thus clear, this application technical scheme can make silicon-based ceramic membrane have moderate heat conduction speed, excellent calorifics characteristic has, when being used for the micro-heating plate, make the temperature maintain the best operating temperature at the catalyst, avoid the emergence of the too high and low problem of temperature.

The stress of the ceramic film 12 is between 100MPa and 1000MPa, inclusive. Specifically, the stress of the ceramic film 12 is 200Mpa, 500Mpa, 800Mpa or 900Mpa. The ceramic film 12 with the stress value is formed on the surface of the silicon substrate 11, so that the ceramic film 12 has excellent mechanical characteristics, can bear larger stress, and avoids the problem that the ceramic film warps or falls off due to stress change.

The ceramic film 12 is polished such that the roughness of the ceramic film 12 is between 0.5nm and 1 μm, inclusive. Specifically, the roughness of the ceramic film 12 may be 10nm, 100nm, 500nm, or 800nm. The ceramic film 12 with the roughness value is formed on the surface of the silicon substrate 11, so that the ceramic film 12 has better flatness and is convenient for manufacturing other structures on the surface.

In the ceramic membrane micro-hotplate according to an embodiment of the present invention, the ceramic membrane 12 completely covers the first surface, or covers a part of the first surface. When the ceramic film 12 covers a part of the first surface, there are a plurality of regions with gaps between adjacent regions. The stress of the silicon substrate 11 is adjusted to be matched with the stress of the ceramic membrane 12 by adjusting the size, the number and the gap distance of the areas divided by the ceramic membrane 12 in the first surface area, so that the stability and the reliability of the ceramic membrane micro-heating plate are ensured.

Referring to fig. 2, fig. 2 is a top view of a ceramic film on the surface of a ceramic film micro-hotplate according to an embodiment of the present invention, where the ceramic film 121 completely covers the first surface of the silicon-based substrate 11 in the manner shown in the left drawing of fig. 2, the ceramic film 123 partially covers the silicon-based substrate 11 in the manner shown in the right drawing of fig. 2, and the ceramic film 122 partially covers the silicon-based substrate 11 in the manner shown in the middle drawing of fig. 2.

The ceramic film micro-hotplate 10 can be arranged to comprise a plurality of layers of ceramic films 12, ceramic slurry of the ceramic films 12 is different, the thickness of the ceramic films 12 is different, so that the stress matching effect of the silicon substrate 11 and the stress matching effect of the ceramic films 12 are better, and the problem of warping of the ceramic film micro-hotplate is avoided.

Referring to fig. 3, fig. 3 is a top view of a functional layer on a surface of a ceramic film micro-hotplate, in which an insulating dielectric layer 16 covers the heating resistors 14 and exposes the heating electrodes 13, so as to facilitate circuit interconnection. As shown in the left diagram of fig. 3, the signal sensing electrode 17 is located on the surface of the insulating medium layer 16, and as shown in the right diagram of fig. 3, the functional module 18 is located on the surface of the insulating medium layer 16 and covers a part of the signal sensing electrode 17. It should be noted that, in the manner shown in fig. 3, the surface of the silicon substrate 11 has the ceramic film 12, and the formation process of the two micro-hotplates at different process stages is shown on the ceramic film 12, and the specific process flow is not limited to the manner shown in fig. 3, which is only for convenience of explaining the structure and interconnection relationship of the signal sensing electrode 17 and the functional module 18.

Referring to fig. 4, fig. 4 is a schematic structural diagram of another ceramic membrane micro-hotplate with a functional layer according to an embodiment of the present invention, in the ceramic membrane micro-hotplate 20 shown in fig. 4, a silicon substrate 21 also has a first surface and a second surface opposite to each other. The embodiment shown in fig. 4 is different from the embodiment shown in fig. 2 in that the surface of the silicon substrate 21 has two ceramic films, i.e., a ceramic film 221 and a ceramic film 222, in the embodiment shown in fig. 4. The ceramic film 221 is located on the surface of the silicon substrate 21, and the ceramic film 222 is located on the surface of the ceramic film 221. The number of layers of the ceramic film may be set according to the stress matching requirement, including but not limited to the two-layer structure shown in fig. 3. The heating layer is arranged on the surface of the outermost ceramic membrane 222, and comprises a heating electrode 23 and a heating resistor 24, the surface of the heating layer is provided with an insulating medium layer 26, and the surface of the insulating medium layer 26 is provided with a functional layer, and the functional layer comprises a signal sensing electrode 27 and a functional module 28 which are electrically connected with each other. The silicon substrate 21 has an air insulating cavity 25 corresponding to the central heating area. The ceramic film micro-heating plate has a structure of overlapping a plurality of ceramic films, so that the stress of the silicon substrate 11 and the stress of the ceramic films are matched with each other, the ceramic film micro-heating plate is free from warping, and the ceramic film micro-heating plate has better performance.

Optionally, the thickness of the heating electrode 13 is 0.5um to 50um, inclusive, such as 10 μm, 20 μm, or 30 μm. The material of the heating electrode 13 is any one of Pt, au, ag, cu, al, ni, W, ag/Pd alloy, and Pt/Au alloy, including but not limited to the above materials.

The heating resistor 14 has a thickness of 0.5um to 50um, inclusive, such as 10 μm, 20 μm, or 30 μm. The heating resistor 14 is a resistor trace with a preset shape formed by patterning a conductive film layer. The picture structure of the conductive film layer can be as shown in fig. 5.

Referring to fig. 5, fig. 5 is a schematic structural diagram of a heating layer according to an embodiment of the present invention, in fig. 5, the heating layer shown in fig. 5a has a heating resistor 141 and a heating electrode 131, and the heating resistor 141 has a profile curve; FIG. 5b shows a heating layer having a heating resistor 142 and a heating electrode 132, the heating resistor 142 having a mosquito coil type curve; the heating layer shown in fig. 5c has a heating resistor 143 and a heating electrode 133, the heating resistor 143 has a serpentine shape, and the line width of the heating resistor 143 is uniform; FIG. 5d shows a heating layer having a heating resistor 144 and a heating electrode 134, wherein the heating resistor 144 has a serpentine shape, and the line width of the heating resistor 144 is not uniform; fig. 5e has heating resistor 144 and heating electrode 134, and heating resistor 144 is rectangular, including long and square. The pattern structure of the heating layer is not limited to the four patterns in fig. 5, is not limited to one pattern structure, and may be a combination of a plurality of pattern structures, as a combination of at least two of the four patterns may be included in one heating layer.

The shape of the heating resistor 14 can be changed according to the uniformity of the thermal field of the micro-hotplate, the line width of the heating resistor can be controlled, and the resistance of the heating resistor can be further regulated, as shown in fig. 5, the width of each line of the heating resistor 143 is the same, and the resistance of each line is also the same. The width of the lines of the heating resistors 144 is inconsistent, the middle of the heating resistors is thick, the two sides of the heating resistors are thin, the middle line resistance is smaller than the line resistances of the two sides, when the same current flows, the joule heat generated by the lines of the two sides is larger than that generated by the line resistance of the middle line, and because the lines of the two sides are closer to the edge of the heat insulation cavity, the heat conduction is higher, so that the temperature of the lines of the two sides is low, and the heat field can be more uniform and consistent through the design of variable line width. Similarly, the heating resistor 142 of the mosquito-repellent incense type curve is also designed to be variable in line width.

The heating resistor is made of a metal film or an alloy film or a metal oxide film. The material of the heating resistor 14 is any one of Pt, au, ag, cu, al, ni, W, mo, ni/Cr alloy, mo/Mn alloy, cu/Zn alloy, ag/Pd alloy, pt/Au alloy, fe/Co alloy, ruO2 and SnO2: sb2O3, including but not limited to the above materials.

The heating electrode 13 and the signal sensing electrode 17 may be prepared by screen-printing an electrode paste through high-temperature sintering. The same electrode paste or different electrode pastes can be used for both. Specifically, the two electrodes may be formed by a fine screen printing technique. The ceramic-based micro-hotplate provided by the embodiment of the invention can be used for MEMS.

The material composition of the insulating medium layer 16 is the same as that of the ceramic film 12, so that the insulating medium layer 16 and the ceramic film 12 have the same material structure and stronger bonding force. The insulating medium layer 16 covers the heating resistor 14, and exposes the heating electrode 13.

The insulating dielectric layer 16 is formed in the same manner as the ceramic film 12. The thickness of the insulating medium layer 16 is 1 um-10 um. The resistivity of the insulating medium layer 16 is more than 10 ¹³ Omega cm. The material of the functional module 18 includes any one of a gas sensitive material, a pyroelectric material, and a photoelectric material.

In the embodiment of the present invention, the ceramic film 12 is different from a conventional ceramic film that is to realize ferroelectric, piezoelectric, or magnetoelectric coupling effects, the ceramic film of the conventional ceramic film is a functional ceramic and needs to have excellent conversion performance between force and electromagnetism, and the ceramic film 12 of the embodiment of the present invention is a structural ceramic and can realize mechanical parameters such as stress strain, elastic modulus, and the like, so that the ceramic film and an adjacent film have reliable and stable adhesion.

Therefore, the ceramic film 12 in the embodiment of the present application is a structural ceramic, the conventional ceramic film layer is a functional ceramic, and has a different nature, and the functional ceramic of the silicon substrate is different from the silicon-based ceramic film of the present application. The functional ceramic mainly utilizes ceramic materials with non-mechanical properties, and the ceramic materials usually have one or more functions such as electricity, magnetism, light, heat, chemical biology and the like, or have coupling functions such as piezoelectricity, piezomagnetism, thermoelectricity, electrooptical, acousto-optic, magneto-optic and the like. With the development of semiconductor technology, functional ceramics are deposited on a silicon substrate in the form of thin films and metal electrodes are evaporated, and the functional properties of ceramic materials are mainly researched and utilized. The ceramic membrane material provided by the embodiment of the invention can enable the ceramic membrane and the silicon substrate to have good mechanical properties matched with each other, and the non-mechanical properties of the traditional ceramic membrane are not required.

The ceramic film in the embodiment of the invention can combine a ceramic film with a microscopic size with a silicon substrate which is easy to be micro-machined, and can be suitable for the field of MEMS micro heaters.

As described above, based on the difference from the conventional functional ceramic, the ceramic film in the embodiment of the present invention may achieve specific mechanical properties, and needs to have specific stress and thermal expansion coefficient, and some electrical performance parameters, such as dielectric constant range is only 3-10, the conventional functional ceramic, such as piezoelectric ceramic and ferroelectric ceramic, generally needs to have higher dielectric constant better, and higher dielectric constant makes the functionality better, and the dielectric constants of the piezoelectric ceramic and the ferroelectric ceramic are usually thousands to tens of thousands, so the technical scheme of the present invention focuses on the selection of the ceramic film material to have excellent mechanical properties, while the mechanical properties of most functional ceramic materials do not satisfy the technical scheme requirements of the present invention, the technical scheme of the present invention does not include a functional layer ceramic material with poor mechanical properties, such as the ceramic film in the embodiment of the present invention has certain elasticity and deformation when heated, if the piezoelectric material is used, intelligent deformation may generate charges at both ends, and will certainly affect the subsequent application expansion of the ceramic film.

In the technical scheme of the embodiment of the invention, after the ceramic slurry is set to form a film on the surface of a silicon substrate by a thick film printing technology, a ceramic film with target characteristics can be formed by high-temperature sintering at a set temperature, and the ceramic film with the target characteristics has excellent electrical resistivity, thermal expansion coefficient, dielectric constant, thermal conductivity and stress characteristics, and the electrical resistivity, the thermal expansion coefficient, the dielectric constant, the thermal conductivity and the stress of the ceramic film meet the set numerical range, and has excellent electrical, thermal and mechanical characteristics, so that the ceramic film micro-hotplate has better stability and reliability.

Compared with the prior art, in the ceramic membrane micro-hotplate provided by the embodiment of the invention, a mature micro-processing technology of the silicon substrate is combined with excellent electrical, mechanical and thermal properties of ceramic, so that a functional circuit can be formed on the ceramic membrane, and micro-structure processing is realized on the silicon substrate. And a ceramic film can be formed by adopting a thick film printing process with low cost, expensive physical vapor deposition or chemical vapor deposition equipment is not required, and the reduction of the product cost is facilitated.

Compared with the traditional physical vapor deposition, in the ceramic-based micro-hotplate disclosed by the embodiment of the invention, the heating layer has better high-temperature resistance, and the stability and reliability of a product are ensured. In the heating layer, the heating resistor and the heating electrode can be prepared simultaneously by using the same conductive paste. In other embodiments, the resistance paste and the electrode paste may be prepared separately, for example, the heating resistor may be prepared by screen printing the resistance paste and sintering at high temperature, and the heating electrode may be prepared by screen printing the electrode paste and sintering at high temperature.

Based on the ceramic-based micro-hotplate in the above embodiment, another embodiment of the present invention further provides a preparation method for preparing the ceramic-based micro-hotplate, the preparation method is shown in fig. 6, and fig. 6 is a schematic flow diagram of the preparation method provided in the embodiment of the present invention, and the preparation method includes:

step S11: providing a silicon substrate, wherein the silicon substrate is provided with a first surface and a second surface which are opposite; the first surface has a central heating zone and a peripheral support zone.

The materials and thicknesses of the silicon substrate can be referred to the above description, and are not described in detail herein.

Step S12: and forming a film layer for setting ceramic slurry on the first surface.

Ceramic slurry is prepared according to the desired target characteristics of the ceramic membrane. The ceramic slurry can be composed of ceramic powder and an organic carrier. Specifically, the ceramic powder has three implementation modes, one is a mixed material of a glass and a ceramic system, the other is a microcrystalline glass system, and the other is single-phase ceramic. The implementation of the setting of the ceramic slurry can refer to the above description, and details are not repeated herein.

The film may be formed on the silicon substrate by any one of screen printing, offset printing, gravure printing, letterpress printing, casting, blade coating, and spraying using the above ceramic slurry.

Step S13: and forming a ceramic film attached to the first surface through drying and sintering processes in sequence.

The target properties of the ceramic film can be found in the above description and will not be described in detail. Through high-temperature sintering at a set temperature, a ceramic film with a certain thickness can be formed on the surface of the silicon substrate, and the ceramic film is compact and hard and has good adhesive force with the silicon substrate.

Optionally, the temperature for drying is 40-200 deg.C, such as 50 deg.C, 80 deg.C, 100 deg.C or 150 deg.C. By adopting the temperature value for drying, better drying effect can be ensured, poor drying quality of the film layer caused by overhigh temperature or overlow temperature is avoided, the subsequent sintering quality is influenced, and the reliability and the stability of the ceramic film are ensured.

Optionally, the sintering temperature is 500-1400 deg.C inclusive, such as 550 deg.C, 800 deg.C, 1000 deg.C or 1200 deg.C. The temperature value is adopted for sintering, so that a better sintering effect can be ensured, the ceramic membrane is compact, has good hardness characteristic and stronger adhesive force with the silicon substrate, the phenomenon that the sintering of the membrane layer is poor due to overhigh temperature or overlow temperature is avoided, and the reliability and the stability of the ceramic membrane are ensured. After the set slurry is formed into a film on the surface of the silicon substrate through a thick film printing process, a ceramic film with large thickness and good dense adhesive force can be formed after sintering, the contact surfaces of the ceramic film and the silicon substrate are in stable contact with each other, and compared with expensive physical vapor deposition or chemical vapor deposition equipment, the ceramic film and the silicon substrate have different contact structures, the contact structures are more reliable and stable, and the manufacturing cost is low.

After sintering, the preparation method further comprises a grinding and polishing process, so that the roughness of the ceramic membrane is 0.5nm-1 μm, inclusive.

Step S14: and forming a conductive film layer with set conductive slurry on the surface of the ceramic film.

Step S15: and forming a heating layer attached to the surface of the ceramic membrane through drying and sintering processes in sequence.

A conductive film layer of the conductive paste can be formed on the surface of the ceramic membrane through a screen printing process, and the heating layer with good adhesion with the ceramic membrane is obtained through drying and sintering processes. The temperature ranges for baking and sintering are the same as above. The drying temperature of the ceramic membrane and the heating layer can be the same or different, and the sintering temperature can be the same or different. In the step, after sintering is finished, the roughness of the heating layer can be enabled to be 0.5nm-1 μm, inclusive, through a grinding and polishing process. The heating layer is provided with a set pattern structure by setting the screen printing screen plate pattern so as to form the heating resistor and the heating electrode with specific structures.

Step S16: and forming an insulating medium layer on the surface of the heating layer.

In this step, the forming of the insulating medium layer on the surface of the heating layer includes:

firstly, forming a film layer of set slurry on the surface of the heating layer; the film layer may be formed on the surface of the heating layer by any one of screen printing, offset printing, gravure printing, letterpress printing, casting, blade coating, and spraying using a set paste.

And then, sequentially drying and sintering the film layer to form the insulating medium layer. The sintering and drying temperatures are the same as or different from the above modes, and a compact and smooth insulating medium layer is formed after drying and sintering.

Step S17: and forming a functional layer on the surface of the insulating medium layer, wherein the functional layer comprises a signal sensing electrode and a functional module which are electrically connected with each other, and the functional module is used for sensing an external signal.

In this step, the forming a functional layer on the surface of the insulating medium layer includes:

firstly, respectively printing the slurry of the signal sensing electrode and the slurry of the functional module on the insulating medium layer through a screen printing process; the first film layer of the signal sensing electrode may be first formed by paste of the signal sensing electrode, and then the second film layer of the functional module, which covers a portion of the first film layer, may be formed by paste of the functional module.

And then, sequentially drying and sintering to form the signal sensing electrode and the functional module which are attached to the surface of the insulating medium layer. And meanwhile, the first film layer and the second film layer are dried and sintered, and the second film layer covers part of the first film layer, so that the first film layer and the second film layer have strong adhesive force and good ohmic contact performance. The sintering and drying temperatures are the same as or different from the above way, and a signal sensing electrode with good adhesive force and a functional module are formed. In other manners, the first film layer may be dried and sintered first, then the second film layer is formed, and then the second film layer is dried and sintered.

Step S18: and etching the second surface to form an air heat insulation cavity penetrating through the first surface and the second surface corresponding to the central heating area.

The air-insulated chamber may be formed using a deep silicon etch process. Specifically, a photoresist layer is formed on the second surface, the photoresist layer can be formed through a spin coating process, the photoresist layer is subjected to graphical exposure and graphical development, a photoresist layer with a preset pattern structure is formed, photoresist right facing a peripheral supporting area is reserved, the photoresist right facing a central heating area is removed, then the patterned photoresist layer is used as a mask to etch the silicon substrate, an air heat insulation cavity is formed, a ceramic membrane of the central heating area is suspended, and finally the photoresist of an edge supporting area is removed, so that the ceramic-based micro-hotplate with good heat insulation performance is formed. The photoresist may be a positive or negative photoresist. The photoresist layer has a thickness of 1 μm to 30 μm, inclusive.

Referring to fig. 7, fig. 7 is a top view of a ceramic-based micro-hotplate according to an embodiment of the present invention, in the manufacturing method according to an embodiment of the present invention, a plurality of ceramic-based micro-hotplates can be simultaneously manufactured from a large-sized wafer, and then the ceramic-based micro-hotplate is divided into a plurality of single ceramic-grain ceramic-based micro-hotplates by a cutting process, wherein each ceramic micro hotplate after cutting has a silicon substrate 11, a ceramic film 12 and a heating layer. As shown in fig. 7, a ceramic film 12 is formed on the wafer. The heating layer pattern on the ceramic membrane 12 comprises a plurality of sub-areas, each sub-area comprising a heating electrode 13 and a heating resistor 14. After an air heat insulation cavity is formed corresponding to the central heating area of each subarea, the large-size wafer is divided into a plurality of small-size silicon substrates 11 through a cutting process, and each small-size silicon substrate 11 corresponds to one subarea to form a single-grain ceramic-based micro-hotplate.

Referring to fig. 8, fig. 8 is a schematic flow chart of another preparation method according to an embodiment of the present invention, where the preparation method includes:

step S21: providing a silicon substrate and cleaning the silicon substrate.

The silicon substrate can be a monocrystalline silicon substrate 11 with double-sided oxidation and 100 crystal orientations, and can be ultrasonically cleaned by acetone for 10min, then ultrasonically cleaned by isopropanol for 5min, then cleaned by deionized water for 5min, and dried by nitrogen.

Step S22: preparing ceramic slurry, forming a film on the surface of the silicon substrate by adopting the slurry, and drying.

Ceramic powder with proper specification is selected, and an organic carrier is added to prepare ceramic slurry. The printing can be performed on the substrate 11 by screen printing and drying at a certain temperature.

Step S23: and putting the dried silicon substrate into a muffle furnace for sintering to form the ceramic membrane.

Obtaining a dense and hard ceramic film 12 with the thickness of 10um, and processing the surface of the ceramic film 12 by adopting a grinding and polishing mode, so that the surface roughness of the ceramic film 12 is controlled to be 0.2um.

Step S24: and forming a pattern structure of a heating electrode and a heating resistor on the surface of the ceramic membrane by adopting the conductive paste through a screen printing process.

The heating electrode and the heating resistor can adopt the same conductive paste, and a corresponding pattern structure is formed through one-time screen printing. In other modes, the heating electrode paste and the heating resistance paste are respectively printed on the ceramic membrane by adopting a screen printing mode to form a corresponding heating electrode pattern structure and a corresponding heating resistance pattern structure.

And after the silk-screen printing is finished, drying and sintering are carried out to obtain the heating electrode and the heating resistor, and then the heating electrode and the heating resistor are polished to ensure that the surface roughness of the heating electrode and the heating resistor is 100nm.

Step S25: and forming an insulating medium layer on the heating resistor.

A film layer can be formed on the heating resistor through a screen printing process, and the film layer is dried and sintered to form the insulating medium layer.

Step S26: and forming a functional layer on the insulating medium layer, wherein the functional layer comprises a signal sensing electrode and a functional module.

And respectively forming a first film layer for preparing the signal sensing electrode and a second film layer for preparing the functional module by a screen printing process twice. The first film layer and the second film layer can be treated simultaneously by adopting one drying and sintering process, or the first film layer can be dried and sintered firstly, then the second film layer is formed, and then the second film layer is dried and sintered.

Step S27: and etching the other side of the silicon substrate, and forming an air heat insulation cavity in the central heating area opposite to the heating resistor.

And (2) coating photoresist on the back of the substrate in a spinning mode, drying the substrate on a heat platform, carrying out graphical exposure and graphical development, removing silicon dioxide on the back by a reactive ion etching technology, etching silicon which is not protected by the photoresist on the lower part of the ceramic membrane by a deep silicon etching technology to form a heat insulation air cavity 15, obtaining the ceramic-based micro-hotplate, and obtaining the ceramic-based micro hotplate chip by a cutting technology.

In the prior art, the material for preparing the ceramic film layer has higher sintering temperature, for example, the sintering temperature required for the zirconia ceramic material is not lower than 1350 ℃, and the higher sintering temperature causes that a silicon wafer cannot be used as a substrate because the silicon wafer cannot bear the higher sintering temperature which is close to the melting point (1400 ℃) of the silicon wafer. And the stress of the ceramic film layer prepared by the traditional ceramic material can not be matched with that of the silicon wafer (the integral stress is less than 500 MPa). Meanwhile, a ceramic film layer prepared by the traditional ceramic material cannot form a compact ceramic film, so that the ceramic substrate can be cracked when a deep silicon etching process is adopted subsequently.

In the embodiment of the invention, the silicon-based ceramic film is formed by adopting the specific ceramic slurry, has excellent mechanical characteristics and can have good adhesion effect with a silicon substrate, the sintering temperature of the material for preparing the ceramic film is lower than the melting point temperature of a silicon wafer, for example, for a mixed material of glass and a ceramic system, the sintering temperature is lower than 1200 ℃, the ceramic film is suitable for printing and sintering on the silicon wafer, the thermal expansion coefficient of the prepared ceramic film can be matched with the silicon wafer by adjusting the components and shielding of the ceramic slurry to form reliable mechanical contact, and the problems of warping and falling caused by thermal deformation are avoided.

In order to better illustrate the present invention, specific examples of the method of making ceramic-based micro-hotplates are provided below.

Example 1

Providing a double-side polished and double-side oxidized 4-inch monocrystalline silicon wafer with a 100 crystal orientation, then ultrasonically cleaning the wafer for 15min by using acetone, ultrasonically cleaning the wafer for 5min by using isopropanol, cleaning the wafer for 5min by using deionized water, and drying the wafer by using nitrogen; selecting ceramic powder with proper specification, adding an organic carrier, preparing into ceramic slurry, printing on a wafer by adopting a screen printing mode, and drying for 10min at 120 ℃; and (3) putting the dried wafer into a muffle furnace, sintering for 30min at 1000 ℃ to obtain a dense and hard ceramic membrane with the thickness of 10um, and treating the surface of the ceramic membrane in a grinding and polishing mode to control the surface roughness of the ceramic membrane to be 0.2um.

Printing a snakelike heating resistor array and a heating electrode array with the length and width of 300um multiplied by 300um on a ceramic membrane in a screen printing mode, drying for 5min at 120 ℃, sintering for 15min at 850 ℃ to obtain a heating electrode and a heating resistor, and then polishing the heating electrode and the heating resistor to ensure that the surface roughness of the heating electrode and the heating resistor is 100nm; printing a glass dielectric layer with the length and width of 500um multiplied by 500um on a heating resistor by adopting a screen printing mode, drying for 5min at 120 ℃, and sintering for 10min at 900 ℃ to obtain an insulating dielectric layer; printing a signal sensing electrode on the insulating medium layer, drying at 120 ℃ for 5min, and sintering at 800 ℃ for 20min; finally, according to the function of the micro-hot plate, a functional layer is prepared on the signal sensing electrode;

spin-coating positive photoresist on the back of a substrate, drying for 5min at 100 ℃, carrying out patterned exposure and patterned development to obtain a photoresist unprotected area with the thickness of 10um and the length and width of 500um multiplied by 500um, removing silicon dioxide in the unprotected area through a reactive ion etching technology, etching silicon unprotected by the photoresist through a deep silicon etching technology to form a heat insulation air cavity, obtaining a ceramic-based micro-hotplate, and obtaining the ceramic-based micro hotplate chip with the length and width of 1.0mm multiplied by 1.0mm through a cutting technology.

Example 2

Providing a double-side polished double-side unoxidized 6-inch monocrystalline silicon wafer with a 100 crystal orientation, then ultrasonically cleaning the wafer for 10min by using acetone, ultrasonically cleaning the wafer for 10min by using isopropanol, cleaning the wafer for 5min by using deionized water, and drying the wafer by using nitrogen; selecting ceramic powder with proper specification, adding an organic carrier to prepare ceramic slurry, forming a film on a wafer by adopting a tape casting mode, and drying for 10min at 150 ℃; and (3) placing the dried wafer into a muffle furnace, sintering for 30min at 1000 ℃ to obtain a dense and hard ceramic membrane with the thickness of 20um, and treating the surface of the ceramic membrane in a grinding and polishing mode to control the surface roughness of the ceramic membrane to be 0.2um.

Printing a variable line width snake-shaped heating resistor array with the length and width of 400um multiplied by 400um and a heating electrode array on a ceramic membrane in a screen printing mode, drying for 5min at 130 ℃, sintering for 30min at 900 ℃ to obtain a heating electrode and a heating resistor, and then polishing the heating electrode and the heating resistor to ensure that the surface roughness of the heating electrode and the heating resistor is 50nm; printing a glass dielectric layer with the length and width of 500um multiplied by 500um on a heating resistor by adopting a screen printing mode, drying for 5min at 120 ℃, and sintering for 20min at 900 ℃ to obtain an insulating dielectric layer; printing a signal sensing electrode on the insulating medium layer, drying at 120 ℃ for 5min, and sintering at 850 ℃ for 10min; finally, according to the function of the micro-hot plate, a functional layer is prepared on the signal sensing electrode;

spin-coating positive photoresist on the back of a substrate, drying for 5min at 100 ℃, carrying out patterned exposure and patterned development to obtain a photoresist unprotected area with the thickness of 15um and the length and width of 500um multiplied by 500um, removing silicon dioxide in the unprotected area through a reactive ion etching technology, etching silicon unprotected by the photoresist through a deep silicon etching technology to form a heat insulation air cavity, obtaining a ceramic-based micro-hotplate, and obtaining the ceramic-based micro hotplate chip with the length and width of 1.0mm multiplied by 1.0mm through a cutting technology.

Example 3

Providing a 2-inch monocrystalline silicon wafer which is polished on both sides and oxidized on one side and has a 100-crystal orientation, ultrasonically cleaning the wafer for 10min by using acetone, ultrasonically cleaning the wafer for 10min by using isopropanol, cleaning the wafer for 5min by using deionized water, and drying the wafer by using nitrogen; selecting ceramic powder with proper specification, adding an organic carrier to prepare ceramic slurry, forming a film on the unoxidized surface of the wafer by adopting a blade coating mode, and drying for 10min at 100 ℃; and (3) placing the dried wafer into a muffle furnace, sintering for 30min at 1200 ℃ to obtain a dense and hard ceramic membrane with the thickness of 6um, and treating the surface of the ceramic membrane in a grinding and polishing mode to control the surface roughness of the ceramic membrane to be 0.1um.

Printing a mosquito-repellent incense-shaped heating resistor array with the length and width of 500um multiplied by 500um and a heating electrode array on a ceramic membrane by adopting a screen printing mode, drying for 5min at 150 ℃, sintering for 10min at 1000 ℃ to obtain a heating electrode and a heating resistor, and then polishing the heating electrode and the heating resistor to ensure that the surface roughness of the heating electrode and the heating resistor is 10nm; printing a glass medium layer with the length and width of 600um multiplied by 600um on a heating resistor by adopting a screen printing mode, drying for 5min at 150 ℃, and sintering for 10min at 1000 ℃ to obtain an insulating medium layer; printing a signal sensing electrode on the insulating medium layer, drying at 150 ℃ for 5min, and sintering at 900 ℃ for 20min; finally, according to the function of the micro-hot plate, a functional layer is prepared on the signal sensing electrode;

the method comprises the steps of spin-coating negative photoresist on the back of a substrate, drying at 150 ℃ for 5min, carrying out patterned exposure and patterned development, obtaining an unprotected area of the photoresist with the thickness of 25um and the length and width of 700um x 700um, removing silicon dioxide in the unprotected area through a reactive ion etching technology, etching silicon unprotected by the photoresist through a deep silicon etching technology, forming a heat insulation air cavity, obtaining a ceramic-based micro-hotplate, and obtaining the ceramic-based micro hotplate chip with the length and width of 1.0mm x 1.0mm through a cutting technology.

Example 4

Providing a double-side polished double-side oxidized 8-inch monocrystalline silicon wafer with a 100 crystal orientation, then ultrasonically cleaning the wafer for 10min by using acetone, ultrasonically cleaning the wafer for 5min by using isopropanol, cleaning the wafer for 5min by using deionized water, and drying the wafer by using nitrogen; selecting ceramic powder with proper specification, adding an organic carrier to prepare ceramic slurry, forming a film on a wafer by adopting a screen printing mode, and drying for 10min at 150 ℃; and (3) placing the dried wafer into a muffle furnace, sintering for 60min at 1200 ℃ to obtain a dense and hard ceramic membrane with the thickness of 8um, and treating the surface of the ceramic membrane in a grinding and polishing mode to control the surface roughness of the ceramic membrane to be 0.5um.

Printing a special-shaped heating resistor array with the length and width of 500um multiplied by 500um and a heating electrode array on a ceramic membrane by adopting a screen printing mode, drying for 5min at 150 ℃, sintering for 10min at 1100 ℃ to obtain a heating electrode and a heating resistor, and then polishing the heating electrode and the heating resistor to ensure that the surface roughness of the heating electrode and the heating resistor is 100nm; printing a glass dielectric layer with the length and width of 700um multiplied by 700um on a heating resistor by adopting a screen printing mode, drying for 5min at 150 ℃, and sintering for 10min at 900 ℃ to obtain an insulating dielectric layer; printing a signal sensing electrode on the insulating medium layer, drying at 120 ℃ for 5min, and sintering at 850 ℃ for 20min; finally, according to the function of the micro-hot plate, a functional layer is prepared on the signal sensing electrode;

spin-coating a positive photoresist on the back of a substrate, drying for 5min at 150 ℃, carrying out graphical exposure and graphical development to obtain an unprotected area of the photoresist with the thickness of 10um and the length and width of 800um multiplied by 800um, removing silicon dioxide in the unprotected area by a reactive ion etching technology, etching silicon unprotected by the photoresist by a deep silicon etching technology to form a heat insulation air cavity, obtaining a ceramic-based micro-hotplate, and obtaining the ceramic-based micro hotplate chip with the length and width of 1.5mm multiplied by 1.5mm by a cutting technology.

Example 5

Providing a double-side polished 12-inch monocrystalline silicon wafer with two unoxidized sides and a 100 crystal orientation, then ultrasonically cleaning the wafer for 10min by using acetone, ultrasonically cleaning the wafer for 5min by using isopropanol, cleaning the wafer for 5min by using deionized water, and drying the wafer by using nitrogen; selecting ceramic powder with proper specification, adding an organic carrier, preparing into ceramic slurry, dividing the ceramic slurry into four quadrant areas which are mutually spaced by taking the circle center of a wafer as the center, forming a film on the wafer by adopting a gravure printing mode, and drying for 10min at 150 ℃; and (3) placing the dried wafer into a muffle furnace, sintering for 20min at 1300 ℃ to obtain a compact and hard ceramic membrane with the thickness of 25um, and treating the surface of the ceramic membrane in a grinding and polishing mode to control the surface roughness of the ceramic membrane to be 0.5um.

Printing a square heating resistor array with the length and width of 300um multiplied by 300um and a heating electrode array on a ceramic membrane by adopting a screen printing mode, drying for 5min at 130 ℃, sintering for 60min at 800 ℃ to obtain a heating electrode and a heating resistor, and then polishing the heating electrode and the heating resistor to ensure that the surface roughness of the heating electrode and the heating resistor is 100nm; printing a glass dielectric layer with the length and width of 700um multiplied by 700um on a heating resistor by adopting a screen printing mode, drying for 5min at 150 ℃, and sintering for 10min at 900 ℃ to obtain an insulating dielectric layer; printing a signal sensing electrode on the insulating medium layer, drying at 150 ℃ for 5min, and sintering at 800 ℃ for 20min; finally, according to the function of the micro-hotplate, a functional layer is prepared on the signal sensing electrode;

spin-coating positive photoresist on the back of a substrate, drying for 5min at 150 ℃, carrying out patterned exposure and patterned development to obtain an unprotected area of the photoresist with the thickness of 12um and the length and width of 600um x 600um, removing silicon dioxide in the unprotected area by a reactive ion etching technology, etching the unprotected silicon of the photoresist by a deep silicon etching technology to form a heat insulation air cavity to obtain a ceramic-based micro-hotplate, and obtaining the ceramic-based micro hotplate chip with the length and width of 1.5mm x 1.5mm by a cutting technology.

Example 6

Providing a 10-inch monocrystalline silicon wafer which is subjected to double-side polishing and double-side oxidation and has a 111 crystal orientation, ultrasonically cleaning the wafer for 10min by using acetone, ultrasonically cleaning the wafer for 5min by using isopropanol, cleaning the wafer for 5min by using deionized water, and drying the wafer by using nitrogen; selecting ceramic powder with proper specification, adding an organic carrier, preparing into ceramic slurry, dividing the ceramic slurry into 16 mutually-spaced areas by taking the circle center of a wafer as the center, forming a film on the wafer by adopting a screen printing mode, and drying for 10min at 150 ℃; and (3) putting the dried wafer into a muffle furnace, sintering for 20min at 1100 ℃ to obtain a compact and hard ceramic membrane with the thickness of 15um, and treating the surface of the ceramic membrane in a grinding and polishing mode to control the surface roughness of the ceramic membrane to be 0.8um.

Printing a rectangular heating resistor array with the length and width of 500um multiplied by 400um and a heating electrode array on a ceramic membrane by adopting a screen printing mode, drying for 5min at 150 ℃, sintering for 60min at 850 ℃ to obtain a heating electrode and a heating resistor, and then polishing the heating electrode and the heating resistor to ensure that the surface roughness of the heating electrode and the heating resistor is 100nm; printing a glass dielectric layer with the length and width of 800um multiplied by 800um on a heating resistor by adopting a screen printing mode, drying for 5min at 130 ℃, and sintering for 10min at 900 ℃ to obtain an insulating dielectric layer; printing a signal sensing electrode on the insulating medium layer, drying at 150 ℃ for 5min, and sintering at 850 ℃ for 20min; finally, according to the function of the micro-hotplate, a functional layer is prepared on the signal sensing electrode;

spin-coating a positive photoresist on the back of a substrate, drying for 5min at 150 ℃, carrying out graphical exposure and graphical development to obtain an unprotected area of the photoresist with the thickness of 8um and the length and width of 600um x 600um, removing silicon dioxide in the unprotected area by a reactive ion etching technology, etching silicon unprotected by the photoresist by a deep silicon etching technology to form a heat insulation air cavity, obtaining a ceramic-based micro-hotplate, and obtaining the ceramic-based micro hotplate chip with the length and width of 1.2mm x 1.2mm by a cutting technology.

According to the description, the preparation method for searching the book is used for preparing the ceramic-based micro-hotplate, expensive physical vapor deposition equipment and chemical vapor deposition equipment are not needed, the ceramic membrane and the heating layer can be formed through a thick film printing process with low cost and drying and sintering processes, the manufacturing cost is low, the high-temperature-resistant heating layer can be formed, and the stability and the reliability of the product are improved.

In the present specification, the embodiments are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. The preparation method disclosed in the embodiment corresponds to the ceramic-based micro-hotplate disclosed in the embodiment, so that the description is relatively simple, and the relevant points can be illustrated by referring to the corresponding parts of the ceramic-based micro-hotplate.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A ceramic-based micro-hotplate with a functional layer, comprising:

a ceramic film disposed on a first surface of the silicon substrate; the ceramic film arranged on the first surface of the silicon substrate is one or more layers of ceramic films;

the ceramic film is formed by sintering set ceramic slurry formed on the surface of the silicon substrate; the heating layer is formed by sintering set conductive slurry formed on the surface of the ceramic membrane;

wherein the ceramic slurry is a mixed material of glass and a ceramic system;

or, the ceramic slurry is a microcrystalline glass system;

alternatively, the ceramic slurry is a single phase ceramic.

2. The ceramic-based micro-hotplate according to claim 1, wherein the silicon substrate is a double-sided, single-sided or unoxidized single crystal silicon wafer with a crystal orientation of 100 or 111;

3. The ceramic-based micro-hotplate of claim 1, wherein the silicon substrate is 50-700 μ ι η thick, inclusive.

4. The ceramic-based micro-hotplate according to claim 1, wherein the ceramic membrane has a thickness of 1-50 μ ι η, inclusive.

5. The ceramic-based micro-hotplate according to claim 1, wherein the ceramic membrane has an electrical resistivity of more than 10 ¹³ Ω·cm。

6. The ceramic-based micro-hotplate according to claim 1, wherein the ceramic membrane has a coefficient of thermal expansion of 0.5 x 10 ^-6 /℃-10×10 ^-6 /° c, inclusive.

7. The ceramic-based micro-hotplate according to claim 1, wherein the ceramic membrane has a dielectric constant of 3-10, inclusive.

8. The ceramic-based micro-hotplate according to claim 1, wherein the ceramic membrane has a thermal conductivity of 0.5W/(m-K) -10W/(m-K), inclusive.

9. The ceramic-based micro-hotplate according to claim 1, wherein the ceramic membrane has a stress of 100-1000 MPa, inclusive.

10. The ceramic-based micro-hotplate according to claim 1, characterized in that the ceramic membrane is polished such that the roughness of the ceramic membrane is 0.5nm-1 μ ι η, inclusive.

11. The ceramic based micro-hotplate according to claim 1, wherein the ceramic membrane covers the first surface completely or covers a portion of the first surface.

12. The ceramic based micro-hotplate according to claim 1, wherein the ceramic based micro-hotplate comprises a plurality of ceramic membranes, the ceramic slurry of the ceramic membranes being different and the thickness of the ceramic membranes being different.

13. The ceramic-based micro-hotplate according to claim 1, wherein when the ceramic slurry is a mixed material of glass and ceramic system, the ceramic phase material in the ceramic slurry comprises one or more of alumina ceramic, magnesia ceramic, beryllia ceramic, zirconia ceramic, aluminum nitride ceramic, silicon nitride ceramic, boron nitride ceramic, titanium nitride ceramic, silicon carbide ceramic, titanium carbide ceramic, and boron carbide ceramic, the glass phase material is an amorphous solid with irregular structure prepared by adding a plurality of inorganic minerals as main raw materials and auxiliary raw materials, and the crystal grains of the ceramic phase material are fused into the amorphous grid of the glass phase material to form the ceramic membrane.

14. The ceramic-based micro-hotplate according to claim 1, wherein when the ceramic slurry is a microcrystalline glass system, the microcrystalline glass in the ceramic slurry is a solid composite material containing both a crystalline phase and a glass phase formed from a base glass by a heat treatment;

wherein the base glass comprises a multicomponent oxide, and under a set condition, a part of the base glass forms a regular arrangement and forms a microcrystalline glass phase in a glass phase.

15. The ceramic-based micro-hotplate according to claim 14, wherein the base glass comprises one or more of a silicate glass, an aluminosilicate glass, a borate glass, a borosilicate glass, a fluorosilicate glass, a phosphosilicate glass.

16. The ceramic-based micro-hotplate according to claim 14, wherein the ceramic paste has a microcrystalline glass phase comprising MgO-Al ₂ O ₃ -SiO ₂ Cordierite system, li ₂ O-Al ₂ O ₃ -SiO ₂ Spodumene system, li ₂ O-ZnO-Al ₂ O ₃ -SiO ₂ Spodumene system, baO-Al ₂ O ₃ -SiO ₂ Barium feldspar system, baO-Al ₂ O ₃ -SiO ₂ -TiO ₂ Celsian system, caO-Al ₂ O ₃ -SiO ₂ Anorthite system, caO-B ₂ O ₃ -SiO ₂ Calborosilicate glass System, li ₂ O-ZnO-MgO-Al ₂ O ₃ -SiO ₂ Beta-quartz system, F-K ₂ O-Na ₂ O-CaO-SiO ₂ Wollastonite system, F-X-MgO-SiO ₂ Fluoroamphibole system, F-X-MgO-Al ₂ O ₃ -SiO ₂ Fluoromica System, P ₂ O ₅ -Li ₂ O-SiO ₂ Any one or more of the lithium silicate systems.

17. The ceramic based micro-hotplate of claim 1, wherein when the ceramic slurry is a single phase ceramic, the single phase ceramic in the ceramic slurry is a barium tin borate ceramic or a barium zirconium borate ceramic.

18. The ceramic-based micro-hotplate according to claim 1, wherein the heating electrode has a thickness of 0.5-50 μ ι η, inclusive;

19. The ceramic-based micro-hotplate according to claim 1, characterized in that the heating resistor has a thickness of 0.5-50 μ ι η, inclusive;

the heating resistor is made of Pt, au, ag, cu, al, ni, W, mo, ni/Cr alloy, mo/Mn alloy, cu/Zn alloy, ag/Pd alloy, pt/Au alloy, fe/Co alloy and RuO ₂ And SnO ₂ :Sb ₂ O ₃ Any one of the above.

20. The ceramic-based micro-hotplate according to claim 1, characterized in that the thickness of the insulating dielectric layer is 1-10 μm.

21. The ceramic-based micro-hotplate according to claim 1, wherein the dielectric layer has a resistivity greater than 10 ¹³ Ω·cm。

22. A method of making a ceramic-based micro-hotplate, for making a ceramic-based micro-hotplate according to any one of claims 1-21, comprising:

forming a film layer of set ceramic slurry on the first surface;

sequentially performing drying and sintering processes to form a ceramic membrane attached to the first surface;

forming an insulating medium layer on the surface of the heating layer;

23. The method of claim 22, wherein the process temperature during drying is between 40 ℃ and 200 ℃, inclusive;

the process temperature during sintering is 500 ℃ to 1400 ℃, inclusive.

24. The method of claim 22, wherein forming the insulating medium layer on the surface of the heating layer comprises:

forming a film layer of set slurry on the surface of the heating layer;

and drying and sintering the film layer in sequence to form the insulating medium layer.

25. The method for preparing the insulating dielectric layer according to claim 22, wherein the step of forming the functional layer on the surface of the insulating dielectric layer comprises:

and sequentially drying and sintering to form the signal sensing electrode and the functional module which are attached to the surface of the insulating medium layer.