CN110655034A - Ceramic-based micro-hotplate and preparation method thereof - Google Patents

Abstract

The invention discloses a ceramic-based micro-heating plate and a preparation method thereof.A ceramic membrane and a heating layer are sequentially formed on a first surface of a silicon substrate, the ceramic membrane is formed by sintering set ceramic slurry, the heating layer is formed by sintering set conductive slurry, and therefore, the ceramic membrane and the heating layer are both formed by a high-temperature sintering process and have better high-temperature resistance, so that the heating layer has better high-temperature resistance and can improve the stability and the reliability compared with the prior art of forming the heating layer by physical vapor deposition under low-temperature process conditions. 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, compared with chemical vapor deposition and physical vapor deposition equipment, the equipment for forming the ceramic membrane and the heating layer by sintering the corresponding slurry has the advantages of lower equipment cost and reduced manufacturing cost.

Description

Ceramic-based micro-hotplate and preparation method thereof

Technical Field

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

Background

Micro Hot Plate (MHP) based on silicon micromachining 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 passes through the resistor strip, one part of joule heat generated by the resistor is used for heating the micro-heating plate, and the other part of joule heat is dissipated in a suspended structure in the surrounding environment in a conduction, convection and radiation mode, so that the micro-heating plate has 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. The micro-hotplate therefore has a very fast thermal response time and a 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 substrate by adopting a chemical vapor deposition technology, prepare a patterned resistance heating film by adopting a physical vapor deposition technology, and then etch the silicon wafer substrate 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 existing micro-hotplate adopts a resistance heating film prepared by physical vapor deposition, which is usually platinum, tungsten, molybdenum or polysilicon with a thickness of several hundred nanometers, and because of the small thickness and small film forming crystal grains, when the micro-hotplate is subjected to high-temperature heat treatment (above 600 ℃), the heating resistance is usually irreversibly changed, and after the high-temperature treatment, the resistance is usually changed not only by a gold wire ball-bonding process due to surface oxidation, or when the sensor is heated to a certain high temperature (above 600 ℃), for example, a catalytic combustion gas sensor based on a silicon-based micro hotplate, when the sensor is exposed to high-concentration combustible gas, the temperature of the micro hotplate may reach seven-eight hundred degrees centigrade due to the heat release of the catalytic combustion of the combustible gas, if the micro hotplate can not bear the temperature, the reliability of the micro hotplate is a problem, which restricts the use environment of the micro hotplate, the product robustness is tested. 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.

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 product stability and reliability; 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, the physical vapor deposition equipment and the chemical vapor deposition equipment are expensive, so that the manufacturing cost is high, and the cost of the micro-hot plate is not further reduced.

Disclosure of Invention

In order to solve the problems, the technical scheme of the invention provides the ceramic-based micro-hotplate which has the advantages of good stability and reliability, simple manufacturing process, low manufacturing cost and low heating power consumption.

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

a 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 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 non-oxidation, 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 μm to 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 10¹³Ω·cm。

Preferably, in the ceramic-based micro-hotplate, the ceramic membraneHas a coefficient of thermal expansion of 0.5X 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 formed by heating a base glass and containing 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 — Al₂O₃-SiO₂Cordierite system, Li₂O-Al₂O₃-SiO₂Spodumene system, Li₂O-ZnO-Al₂O₃-SiO₂Spodumene system, BaO-Al₂O₃-SiO₂Barium feldspar system, BaO-Al₂O₃-SiO₂-TiO₂Celsian system, CaO-Al₂O₃-SiO₂Anorthite system, CaO-B₂O₃-SiO₂Calborosilicate glass System, Li₂O-ZnO-MgO-Al₂O₃-SiO₂Beta-quartz system, F-K₂O-Na₂O-CaO-SiO₂Wollastonite system, F-X-MgO-SiO₂Fluoroamphibole system, F-X-MgO-Al₂O₃-SiO₂Fluoromica System, P₂O₅-Li₂O-SiO₂Any 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 material of the heating electrode is any one of Pt, Au, Ag, Cu, Al, Ni, W, Ag/Pd alloy and Pt/A u 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.

The invention also provides a preparation method of the ceramic-based micro-hotplate, which is characterized in that the preparation method comprises 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;

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.

As can be seen from the above description, in the ceramic-based micro-hotplate and the preparation method thereof provided by the technical scheme of the invention, 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, and the heating layer is formed by sintering the set conductive slurry. 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, compared with chemical vapor deposition and physical vapor deposition equipment, the equipment for forming the ceramic membrane and the heating layer by sintering the corresponding slurry has the advantages of lower equipment cost and reduced manufacturing cost.

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 description of the embodiments or the prior art 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 according to an embodiment of the present invention;

FIG. 2 is a top view of a ceramic membrane micro-hotplate according to an embodiment of the present invention;

FIG. 3 is a schematic structural diagram of another ceramic membrane micro-hotplate according to an embodiment of the present invention;

fig. 4 is a schematic structural diagram of a heating layer according to an embodiment of the present invention;

FIG. 5 is a schematic flow chart of a preparation method provided by an embodiment of the invention;

FIG. 6 is a top view of a ceramic-based micro-hotplate according to an embodiment of the invention;

fig. 7 is a schematic flow chart of another preparation method provided in the embodiment of the 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 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.

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 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 film 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. 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.

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 film 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.

Compared with the prior art, the ceramic membrane 12 and the heating layer of the ceramic-based micro-hotplate 10 provided by the embodiment of the invention are prepared by respectively forming a membrane by using a 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, 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 amorphous solid with a random structure, which is prepared by adding auxiliary raw materials into a main raw material of a plurality of inorganic minerals (comprising one or more of quartz sand, borax, boric acid, barite, barium carbonate, limestone, potassium feldspar, albite, soda ash, zinc oxide, bismuth oxide, lead oxide, copper oxide, chromium oxide and the like), 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 the high temperature condition, the crystal grains of the ceramic phase material are fused into the amorphous grid 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-Al₂O₃-SiO₂Cordierite system, Li₂O-Al₂O₃-SiO₂Spodumene system, Li₂O-ZnO-Al₂O₃-SiO₂Spodumene system, BaO-Al₂O₃-SiO₂Barium feldspar system, BaO-Al₂O₃-SiO₂-TiO₂Celsian system, CaO-Al₂O₃-SiO₂Anorthite system, CaO-B₂O₃-SiO₂Calborosilicate glass System, Li₂O-ZnO-MgO-Al₂O₃-SiO₂Beta-quartz system, F-K₂O-Na₂O-CaO-SiO₂Wollastonite system, F-X-MgO-SiO₂Fluorite system (X is oxide of Li, Na, K, Ca, etc.), F-X-MgO-Al₂O₃-SiO₂Fluoromica system (X is alkali metal or alkaline earth metal oxide), P₂O₅-Li₂O-SiO₂Any 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 10¹³Omega cm. The silicon-based ceramic film 10 according to the embodiment of the present invention has a relatively high 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^-6V. 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 the stability of the ceramic film micro-heating plate 10 are ensured.

The ceramic film 12 has a dielectric constant of 3-10, 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/(mK), 4W/(mK), 6W/(mK), or 8W/(mK). 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 900 Mpa. 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 800 nm. 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 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 micro-hotplate according to an embodiment of the present invention, wherein the ceramic film 121 completely covers the first surface of the silicon-based substrate 11 in the manner shown in the left diagram of fig. 2, the ceramic film 123 partially covers the silicon-based substrate 11 in the manner shown in the right diagram of fig. 2, and the ceramic film 122 partially covers the silicon-based substrate 11 in the manner shown in the middle diagram of fig. 2.

The ceramic film micro-hotplate 10 can be arranged to comprise a plurality of layers of ceramic films 12, wherein ceramic slurry of the ceramic films 12 is different and the thicknesses of the ceramic films 12 are 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 substrate micro-hotplate is avoided.

Referring to fig. 3, fig. 3 is a schematic structural diagram of another ceramic membrane micro-hotplate according to an embodiment of the present invention, in the ceramic membrane micro-hotplate 20 shown in fig. 3, a silicon substrate 21 also has a first surface and a second surface opposite to each other, which are the same as the silicon substrates of the previous embodiments. The method shown in fig. 3 is different from the method 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 method shown in fig. 3. 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. On the surface of the outermost ceramic membrane 222 is provided a heating layer, which comprises heating electrodes 23 and heating resistors 24, as in the above described implementation.

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/A u alloy, including but not limited to the above materials.

The thickness of the heating resistor 14 is 0.5um-50um, including the end point value, 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 conductive film layer drawing structure can be as shown in fig. 4.

Referring to fig. 4, fig. 4 is a schematic structural diagram of a heating layer according to an embodiment of the present invention, in fig. 4, the heating layer shown in fig. 4a has a heating resistor 141 and a heating electrode 131, and the heating resistor 141 has a profile curve; FIG. 4b shows a heating layer having a heating resistor 142 and a heating electrode 132, wherein the heating resistor 142 is a mosquito coil type curve; the heating layer shown in fig. 4c 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. 4d 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. 4e has heating resistor 144 and heating electrode 134, and heating resistor 144 is rectangular. The pattern structure of the heating layer is not limited to the four patterns in fig. 4, 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 can be changed according to the uniformity of the thermal field of the micro-hotplate, the line width of the heating resistor is controlled, and the resistance value of the heating resistor is further regulated and controlled, as shown in fig. 4, the width of each line of the heating resistor 143 is the same, and the resistance value of each line is also the same. And the line width of the heating resistor 144 is inconsistent, the middle is thick, the two sides are thin, the line resistance in the middle is smaller than the line resistance on the two sides, when the same current passes through, the joule heat generated by the lines on the two sides is larger than that generated by the line resistance in the middle, and because the lines on 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 on the two sides is low, and through the design of line width changing, the heat field can be more uniform and consistent. Similarly, the heating resistor 142 of the mosquito-repellent incense type curve is also designed to be variable in line width.

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.

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 is a functional ceramic, and the ceramic film has different essence, and the functional ceramic of the silicon substrate is different from the silicon-based ceramic film of the present application. Functional ceramics mainly use ceramic materials with non-mechanical properties, and such ceramic materials usually have one or more functions, such as electrical, magnetic, optical, thermal, chemical and biological, or coupling functions, such as piezoelectric, piezomagnetic, thermoelectric, electro-optical, acousto-optical, magneto-optical, etc. 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 of the embodiment of the invention can ensure that the ceramic membrane and the silicon substrate 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 mentioned above, based on the difference from the traditional functional ceramics, 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 traditional functional ceramics, such as piezoelectric ceramics and ferroelectric ceramics, generally need higher dielectric constant to be better, and higher dielectric constant to make the functionality better, and the dielectric constants of piezoelectric ceramics and ferroelectric ceramics are usually thousands to tens of thousands, so the technical scheme of the present invention focuses on the selection of ceramic film materials 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 functional layer ceramic materials with poor mechanical properties, such as the ceramic film in the embodiment of the present invention has certain elasticity and deformation when heated, if piezoelectric materials are adopted, intelligent deformation can generate electric charges at two ends, and the subsequent application and expansion of the ceramic membrane are influenced.

According to the technical scheme of the embodiment of the invention, after the ceramic slurry is formed on the surface of the silicon substrate by a thick film printing technology, the ceramic film with the target characteristics can be formed by high-temperature sintering at the set temperature, the ceramic film with the target characteristics has excellent electrical resistivity, thermal expansion coefficient, dielectric constant, thermal conductivity and stress characteristics, 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 the ceramic film micro-hotplate has excellent electrical, thermal and mechanical characteristics, so that the ceramic film micro-hotplate has good 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. 5, and fig. 5 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 material and thickness of the silicon substrate can be referred to the above description, and are not described herein again.

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

Ceramic slurries are 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 is 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 membrane 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 the step of enabling the roughness of the ceramic membrane to be 0.5nm-1 μm inclusive through a grinding and polishing process.

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 described 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 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. 6, fig. 6 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. 6, 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 subregion, 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 subregion to form a single-grain ceramic-based micro-hot plate.

Referring to fig. 7, fig. 7 is a schematic flow chart of another preparation method provided in the embodiment of the present invention, 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 orientation, 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 membrane 12 with the thickness of 10um, and processing the surface of the ceramic membrane 12 by adopting a grinding and polishing mode to control the surface roughness of the ceramic membrane 12 to be 0.2 um.

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 100 nm.

Step S25: 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 high 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 overall 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 may crack 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 good adhesion effect with the silicon substrate, the sintering temperature of the material for preparing the ceramic film is lower than the melting point temperature of the silicon wafer, for example, for the 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, reliable mechanical contact is formed, 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 compact 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 0.2 um.

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 100 nm; spin-coating a positive photoresist on the back of a substrate, drying for 5min at 100 ℃, 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 500um multiplied by 500um, 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 1.0mm multiplied by 1.0mm by 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) putting the dried wafer into a muffle furnace, sintering for 30min at 1000 ℃ to obtain a compact 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 0.2 um.

Adopting a screen printing mode to print 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, 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 50 nm; spin-coating a positive photoresist on the back of a substrate, drying for 5min at 100 ℃, carrying out graphical exposure and graphical development to obtain an unprotected area of the photoresist with the thickness of 15um and the length and width of 500um multiplied by 500um, 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 1.0mm multiplied by 1.0mm by 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) putting 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 0.1 um.

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 10 nm; spin-coating negative 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 25um and the length and width of 700um x 700um, 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 1.0mm x 1.0mm by 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) putting 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 0.5 um.

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 100 nm; 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 0.5 um.

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 100 nm; 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 12um 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 1.5mm 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 0.8 um.

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

The embodiments in the present description 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 referred to the corresponding parts of the ceramic-based micro-hotplate for explanation.

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 (22)

1. A 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 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.

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

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

3. The ceramic-based micro-hotplate according to claim 1, wherein the silicon substrate has a thickness of 50-700 μ ι η, inclusive.

4. The ceramic-based micro-hotplate according to claim 1, characterized in that the ceramic paste is a mixed material of glass and ceramic system;

or, the ceramic slurry is a microcrystalline glass system;

or, the ceramic slurry is a single phase ceramic.

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

6. The ceramic-based micro-hotplate according to claim 1, wherein the ceramic membrane has an electrical resistivity of more than 10¹³Ω·cm。

7. 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.

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

9. 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.

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

11. 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.

12. 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.

13. 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.

14. The ceramic-based micro-hotplate according to claim 4, 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 amorphous solid with irregular structure prepared by adding auxiliary raw materials into a plurality of inorganic minerals as main 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.

15. The ceramic-based micro-hotplate according to claim 4, wherein when the ceramic paste is a microcrystalline glass system, the microcrystalline glass in the ceramic paste is a solid composite material comprising both a crystal orientation and a glass phase formed from a base glass by a heat treatment;

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.

16. The ceramic-based micro-hotplate according to claim 15, 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.

17. The ceramic-based micro-hotplate according to claim 15, wherein the ceramic paste has a microcrystalline glass phase comprising MgO-Al₂O₃-SiO₂Cordierite system, Li₂O-Al₂O₃-SiO₂Spodumene system, Li₂O-ZnO-Al₂O₃-SiO₂Spodumene system, BaO-Al₂O₃-SiO₂Barium feldspar system, BaO-Al₂O₃-SiO₂-TiO₂Celsian system, CaO-Al₂O₃-SiO₂Anorthite system, CaO-B₂O₃-SiO₂Calborosilicate glass System, Li₂O-ZnO-MgO-Al₂O₃-SiO₂Beta-quartz system, F-K₂O-Na₂O-CaO-SiO₂Wollastonite system, F-X-MgO-SiO₂Fluoroamphibole system, F-X-MgO-Al₂O₃-SiO₂Fluoromica System, P₂O₅-Li₂O-SiO₂Any one or more of the lithium silicate systems.

18. The ceramic-based micro-hotplate according to claim 4, 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.

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

the material of the heating electrode is any one of Pt, Au, Ag, Cu, Al, Ni, W, Ag/Pd alloy and Pt/A u alloy.

20. The ceramic-based micro-hotplate according to claim 1, wherein the heating resistor has a thickness of 0.5-50 um, 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.

21. A method of making a ceramic-based micro-hotplate, for making a ceramic-based micro-hotplate according to any one of claims 1-20, comprising:

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;

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.

22. The method of claim 21, wherein the process temperature at the time of oven drying is 40 ℃ to 200 ℃, inclusive;

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

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