CN114459647A - Silicon carbide high-temperature pressure sensor based on optical fiber Fabry-Perot and manufacturing method thereof - Google Patents
Silicon carbide high-temperature pressure sensor based on optical fiber Fabry-Perot and manufacturing method thereof Download PDFInfo
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L1/00—Measuring force or stress, in general
- G01L1/24—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet
- G01L1/242—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet the material being an optical fibre
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
- C23C28/02—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D only coatings only including layers of metallic material
- C23C28/023—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D only coatings only including layers of metallic material only coatings of metal elements only
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L11/00—Measuring steady or quasi-steady pressure of a fluid or a fluent solid material by means not provided for in group G01L7/00 or G01L9/00
- G01L11/02—Measuring steady or quasi-steady pressure of a fluid or a fluent solid material by means not provided for in group G01L7/00 or G01L9/00 by optical means
- G01L11/025—Measuring steady or quasi-steady pressure of a fluid or a fluent solid material by means not provided for in group G01L7/00 or G01L9/00 by optical means using a pressure-sensitive optical fibre
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- Chemical & Material Sciences (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Pressure Sensors (AREA)
Abstract
The invention discloses a method for manufacturing a silicon carbide high-temperature pressure sensor based on an optical fiber Fabry-Perot method, which comprises the following steps of a) selecting a 4H-SiC wafer as a manufacturing material of a silicon carbide sensitive structure; b) manufacturing a wafer with an etching cavity; c) manufacturing a sensitive membrane; d) laser scribing: performing unit cutting on the sensitive membrane and the substrate with the etching cavity by using a laser process; e) hot-pressing bonding: carrying out hot-pressing bonding on the pre-bonded silicon carbide sensitive structure by using a one-way hot-pressing furnace; f) packaging a sensor: packaging the silicon carbide sensitive mechanism subjected to hot-pressing bonding by using a silicon carbide ceramic packaging clamp; a silicon carbide high-temperature pressure sensor based on an optical fiber Fabry-Perot comprises a silicon carbide sensitive structure, a silicon carbide ceramic packaging clamp, a quartz sleeve and an optical fiber. According to the Fabry-Perot cavity, the sensitive membrane and the wafer with the etching cavity are directly bonded by adopting the silicon carbide material to form the Fabry-Perot cavity, so that the Fabry-Perot cavity is good in air tightness and high in bonding strength, the production efficiency of the sensor is improved, and the cost is reduced.
Description
Technical Field
The invention relates to a sensor and a manufacturing method thereof, in particular to a silicon carbide high-temperature pressure sensor based on an optical fiber Fabry-Perot method and a manufacturing method thereof.
Background
The pressure sensor is the most common sensor in industrial practice, is widely applied to various industrial automatic control environments, and relates to a plurality of industries such as water conservancy and hydropower, railway traffic, intelligent buildings, production automatic control, aerospace, military industry, petrochemical industry, oil wells, electric power, ships, machine tools, pipelines and the like.
The optical fiber high-temperature pressure sensor based on the optical fiber Fabry-Perot interference principle has the advantages of being single in integral chip material, free of metal and smaller.
Silicon carbide (SiC) materials are gradually gaining attention due to their excellent mechanical properties and high temperature stability. Of the more than 200 polytypes of SiC, the most common are 3C-SiC, 4H-SiC and 6H-SiC. Among them, single crystal substrates of 4H-SiC and 6H-SiC have been commercialized.
Under the severe environment of high temperature and high pressure, the normal temperature pressure sensor can be realized by an indirect measurement mode, but the acquired data precision is crossed, and the accuracy of the test environment cannot be evaluated in a real-time standard manner. At present, pressure measurement aiming at high-temperature environment mainly adopts a piezoresistive sensor, a capacitive sensor and an optical fiber sensor. However, for the piezoresistive high-temperature pressure sensor, the performance of the piezoresistive high-temperature pressure sensor under extreme environments is limited by factors such as high-temperature deformation of chip materials, mismatching of thermal expansion coefficients of multiple materials and the like; the capacitive high-temperature pressure sensor has a wireless and passive structure, but has a problem of low wireless signal transmission efficiency at high temperature.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a silicon carbide high-temperature pressure sensor based on an optical fiber Fabry-Perot method and a manufacturing method thereof, which can be used in a normal-temperature system and a high-temperature system at the same time and have better high-temperature pressure sensitivity.
The object of the invention is achieved on the one hand by: a manufacturing method of a silicon carbide high-temperature pressure sensor based on an optical fiber Fabry-Perot method comprises the following steps:
a) selecting a 4H-SiC wafer as a manufacturing material of the silicon carbide sensitive structure; the silicon carbide sensitive structure comprises a sensitive membrane and a wafer with an etching cavity;
b) manufacturing a wafer with an etching cavity:
b1) glue homogenizing: selecting a silicon surface of the silicon carbide to carry out a photoetching process, immediately placing the wafer on a heating table to carry out soft baking after the glue is homogenized, and carrying out photoetching after the temperature of the wafer is cooled to room temperature after the soft baking is finished;
b2) photoetching: aligning the mask plate with the wafer, turning on an ultraviolet light source to enable ultraviolet light to penetrate through the mask plate to expose photoresist on the surface of the wafer, and developing the wafer after exposure is finished;
b3) magnetron sputtering: preparing an adhesion layer and a seed layer by adopting a magnetron sputtering process, wherein metals are Cr and Cu, the Cr is used as the adhesion layer between the outer layer metal and the wafer, and the Cu is used as the seed layer of the subsequent electroplating process;
b4) stripping: immersing the wafer into an acetone solution, carrying out ultrasonic stripping, and removing the photoresist and the metal on the surface of the photoresist;
b5) electroplating: selecting metal Ni as etched mask metal, and preparing a metal hard mask by using an electroplating process;
b6) etching the cavity by adopting an etching process: placing the electroplated wafer into an etching machine for etching for a period of time, taking out the electroplated wafer, measuring the depth by using a step instrument, placing the silicon carbide wafer into the etching machine for secondary etching, taking out the silicon carbide wafer, and measuring the depth by using the step instrument;
b7) removing metals: after the plasma etching process is finished, removing the metal mask by respectively adopting Ni corrosive liquid, Cu corrosive liquid and Cr corrosive liquid;
c) production of sensitive diaphragm
c1) Chemical grinding, thinning and polishing by CMP: thinning the silicon carbide wafer to the required thickness by using a thinning machine, and then polishing the wafer by using a polishing machine to eliminate the residual stress on the surface of the wafer in the thinning process;
d) laser scribing: performing unit cutting on the sensitive membrane and the substrate with the etching cavity by using a laser process;
e) hot-pressing bonding: removing the pollution generated by the ablation of the silicon carbide material in the laser scribing process, attracting the cleaned and surface-activated silicon carbide wafer in a methanol solution through the surface interaction force between the wafers to form a spontaneous bond with weaker strength by pre-bonding, and carrying out hot-press bonding on the pre-bonded silicon carbide sensitive structure by using a unidirectional hot-press furnace;
f) packaging a sensor: and packaging the silicon carbide sensitive mechanism subjected to thermal compression bonding by using a silicon carbide ceramic packaging clamp.
In order to ensure that the patterning effect is good and the pollution is low during etching, the etching process in the step b 6) adopts inductively coupled plasma etching equipment in dry etching to etch the silicon carbide material.
In order to make the wafer surface flat and improve the grinding precision, the step c1) specifically includes: 1) sheet sticking: adhering the wafer on a glass substrate, and polishing the C surface of the silicon carbide wafer; 2) before thinning and polishing, the grinding disc is required to be repaired, the thinning grinding disc is repaired by using alumina grinding fluid, and the polishing grinding disc is repaired by using a disc repairing block and deionized water; 3) thinning: firstly, carrying out coarse thinning by using a large-particle-size boron carbide grinding fluid, and then carrying out fine thinning by using a small-particle-size grinding fluid; 4) polishing: polishing by adopting a grinding disc with the surface consisting of a plurality of polyurethane polishing pads, wherein the polishing solution adopts CS series polishing solution; 5) measurement: after the thinning and polishing process is completed, the silicon carbide wafer is taken down from the glass substrate for cleaning, and the wafer is detected by using a thickness gauge.
In order to form a sealed cavity between the sensitive film and the substrate with the cavity, the thermocompression bonding in the step e) specifically comprises: and (3) putting the pre-bonded wafer into a hot-pressing bonding furnace with a customized graphite clamp, adjusting the heating rate by controlling the heating power, applying pressure to the wafer through a hydraulic pump and a pressure head displacement control system after the required temperature is reached, and finally unloading the pressure to cool the temperature in the furnace to room temperature through a water cooling system to finish the direct bonding of the silicon carbide wafer.
The object of the invention is achieved in another aspect by: the silicon carbide high-temperature pressure sensor based on the optical fiber Fabry-Perot is characterized by comprising a silicon carbide sensitive structure, a silicon carbide ceramic packaging clamp, a quartz sleeve and an optical fiber, wherein the silicon carbide ceramic packaging clamp comprises a pressing cover, a connecting sleeve and a rear-end base column with a hole; the silicon carbide sensitive structure comprises a sensitive membrane and a wafer with an etching cavity, wherein the sensitive membrane and the wafer with the etching cavity are bonded to form a Fabry-Perot cavity.
In order to increase the reliability and sensitivity of the sensor, the sensitive membrane is circular in shape.
In order to avoid the performance reduction or the failure of devices caused by the thermal expansion coefficient, the pressing cover is provided with through holes, external threads are arranged on the periphery of the pressing cover, the connecting sleeve is provided with internal threads, and the pressing cover is screwed and fixed with the silicon carbide sensitive structure through the threads.
In order to reduce the use of high-temperature glue, the rear-end base column with the hole is provided with threads, and is fixedly connected with the connecting sleeve in a thread screwing mode.
By adopting the technical scheme, compared with the prior art, the invention has the beneficial effects that: the sensing device in the sensor comprises a sensing diaphragm and a wafer with an etching cavity, the sensing diaphragm and the wafer with the etching cavity are directly bonded by adopting a silicon carbide material to form a Fabry-Perot cavity, the sensing device is packaged and fixed by using silicon carbide ceramics with the thermal expansion coefficient similar to that of the silicon carbide, and the bottom surface of the silicon carbide etching cavity and the bonding surface of the sensing diaphragm are used as two parallel surfaces for Fabry-Perot interference of optical fibers to play a role in light source transmission; the sensor has good and large sensitivity performance in a normal temperature system and a high temperature system; still has good sensitivity characteristic at 600 ℃; the packaging structure greatly reduces the use of high-temperature glue; the silicon carbide wafer is directly bonded, so that the production efficiency of the device is improved, and the production cost is reduced.
Drawings
FIG. 1 is a flow chart of a process for preparing a sensor sensitive structure according to the present invention.
Fig. 2 is a schematic diagram of the structure of the sensor of the present invention.
FIG. 3 is a schematic diagram of an etching chamber mask of the present invention.
Wherein, the sensor comprises a silicon carbide sensitive structure 1, a wafer 2 with an etching cavity, a sensitive membrane 3, a Fabry-Perot cavity 4, a connecting sleeve 5, a rear-end base column 6 with a hole, a quartz sleeve 7 and an optical fiber 8; 201, manufacturing a silicon carbide wafer with an etching cavity, 201 photoresist, 203 an adhesion layer, 204 a seed layer and 205 a metal hard mask; 301 a silicon carbide wafer for making a sensitive membrane.
Detailed Description
As shown in fig. 2, the silicon carbide high-temperature pressure sensor based on fiber fabry-perot comprises a silicon carbide sensitive structure 1 (size 6mm x 6 mm), a silicon carbide ceramic packaging fixture, a quartz sleeve 7 and an optical fiber 8, wherein the silicon carbide ceramic packaging fixture comprises a pressing cover, a connecting sleeve 5 and a rear end pillar 6 with a hole, the silicon carbide sensitive structure 1 is placed in the connecting sleeve 5 and fixed by the pressing cover, the quartz sleeve 7 is fixed in the rear end pillar 6 by high-temperature glue, and the optical fiber 8 is inserted in the quartz sleeve 7; the silicon carbide sensitive structure 1 comprises a sensitive membrane 3 (the thickness is 180 microns) and a wafer 2 with an etching cavity, and the sensitive membrane 3 and the wafer 2 with the etching cavity are bonded to form a Fabry-Perot cavity 4 (the depth of the cavity is about 16 microns). The shape of the sensitive membrane 3 is circular; the pressing cover is provided with a through hole of 3mm, so that the bright sensitive membrane 3 can be completely exposed, the periphery of the pressing cover is provided with external threads, the connecting sleeve 5 is provided with internal threads, and the pressing cover is screwed and fixed with the silicon carbide sensitive structure 1 through the threads; the rear end pillar 6 with the hole is provided with a thread and is fixedly connected with the connecting sleeve in a thread screwing mode; the bottom surface of the silicon carbide etching cavity and the bonding surface of the sensitive diaphragm are used as two planes of Fabry-Perot interference of the optical fiber, the optical fiber plays a role in light source transmission, and the optical fiber end needs to be ensured to be parallel to the surface of the sensor in the assembling process.
As shown in fig. 1, a method for manufacturing a silicon carbide high-temperature pressure sensor based on fiber fabry-perot includes the following steps:
a) selecting a 4H-SiC wafer as a manufacturing material of the silicon carbide sensitive structure; the silicon carbide sensitive structure comprises a sensitive membrane and a wafer with an etching cavity; before use, the silicon carbide wafer needs to be cleaned, and the invasion ratio of the silicon carbide wafer is 3: 1, heating the mixed solution of concentrated sulfuric acid and hydrogen peroxide for 15min at 150 ℃, and effectively removing organic pollution on the surface of the wafer; then placing the wafer into a mixed solution of ammonia water, hydrogen peroxide and water, heating in a water bath for 5min to remove particle pollution on the surface of the wafer, finally flushing the silicon carbide wafer and drying by using nitrogen;
b) manufacturing a wafer 2 with an etching cavity: as shown in fig. 3, the mask type of the etching chamber is a positive plate, a plurality of structural units are arranged on a silicon carbide wafer according to the size of a sensitive structure, each unit comprises a circle with the radius of 2 mm and four cross marks, the circle is an etching chamber pattern, and laser splinter alignment is facilitated;
b1) glue homogenizing: the silicon surface of the silicon carbide wafer is selected to be subjected to a photoetching process, photoresist 202 positive photoresist is used, and the photoresist homogenizing formula is as follows: precoating at 200rpm for 5s, accelerating at 500rpm for 3s, coating at 3000rpm for 60s, placing the wafer on a heating table at 110 ℃ for soft drying after the photoresist is homogenized, removing part of the solvent of the photoresist, enhancing the adhesiveness of the photoresist and relieving the internal stress in the spin coating process, cooling the wafer to room temperature after the soft drying is finished, and then carrying out photoetching;
b2) photoetching: aligning the mask plate with the wafer, turning on an ultraviolet light source to enable ultraviolet light to penetrate through the mask plate to expose photoresist on the surface of the wafer, and developing the wafer after exposure is finished; immersing the exposed wafer into a developing solution, wherein the developing time is 30s, and performing microscopic examination on the developing effect after the developing is finished;
b3) magnetron sputtering: preparing an adhesion layer 203 and a seed layer 204 by adopting a magnetron sputtering process, wherein metals are selected to be 10nmCr and 100nmCu, Cr is used as the adhesion layer 203 between outer layer metal and a wafer, and Cu is used as the seed layer 204 of a subsequent electroplating process; the power of the magnetron sputtering equipment is 150W, and the rotating speed of the substrate is 8 r/min;
b4) stripping: immersing the wafer into an acetone solution and carrying out ultrasonic stripping, wherein the acetone solution can react with the photoresist due to a certain height difference between the two areas to remove the photoresist and the metal on the surface of the photoresist;
b5) electroplating: selecting metal nickel (Ni) as etching mask metal, and preparing a metal hard mask 205 by using an electroplating process; the electroplating thickness is 2 microns;
b6) etching the cavity by adopting an etching process: etching the silicon carbide material by adopting Inductively Coupled Plasma (ICP) etching equipment in dry etching; putting the electroplated wafer into an etching machine for etching for 10min, taking out the wafer, measuring the depth to be 9.5 microns by using a step profiler, wherein the selection ratio of the etching machine to silicon carbide and metal nickel (Ni) is 20: 1, placing the silicon carbide wafer into an etching machine for secondary etching for 10min, taking out the silicon carbide wafer, and measuring the depth by using a step profiler, wherein the height is 17 microns and the designed etching depth is 16 microns; inert gas helium (He) is added in the etching process, the helium does not react with free radicals in the reaction process, and the surface of the silicon carbide wafer is continuously bombarded under the action of bias voltage to remove precipitates formed on the surface;
b7) removing metals: after the plasma etching process is finished, removing the metal mask by respectively adopting Ni corrosive liquid, Cu corrosive liquid and Cr corrosive liquid;
c) manufacturing the sensitive membrane 3:
c1) chemical grinding, thinning and polishing by CMP: thinning the SiC wafer 301 to a required thickness by using a thinning machine, and then polishing the wafer by using a polishing machine to eliminate the residual stress on the surface of the wafer in the thinning process;
1) sheet sticking: selecting a 6-inch silicon carbide wafer with the thickness of 500 micrometers, adhering the wafer to a glass substrate, and selecting the C surface of the silicon carbide wafer for polishing; placing a glass substrate on a heating table, heating to 85 ℃, placing solid quartz wax on the surface of the substrate, melting the solid quartz wax, coating the melted solid quartz wax on the glass substrate, placing a wafer in the center of the glass substrate, continuously pressing the wafer in the placing process to ensure that no bubbles are generated at the bottom of the wafer, then vacuumizing, pressurizing, bonding and water cooling, and finally erasing the silicon carbide wafer and the quartz wax on the edge of the glass substrate by using absolute ethyl alcohol; 2) before thinning and polishing, the grinding disc is required to be repaired, the thinning grinding disc is repaired by using alumina grinding fluid, and the polishing grinding disc is repaired by using a disc repairing block and deionized water; 3) thinning: the required membrane thickness is 180 microns, firstly, 240-mesh large-particle-size boron carbide grinding fluid is used for carrying out coarse thinning, the grinding disc rotating speed is set to be 70r/min, the silicon carbide wafer is thinned to 240 microns, then 600-mesh small-particle-size grinding fluid is used for carrying out fine thinning, the grinding disc rotating speed is 50r/min, and the silicon carbide wafer is thinned to 185 microns; 4) polishing: polishing by adopting a grinding disc with the surface consisting of a plurality of polyurethane polishing pads, wherein the polishing solution adopts CS series polishing solution; 5) and (3) measurement: after the thinning and polishing process is completed, the silicon carbide wafer is taken down from the glass substrate for cleaning, and the wafer is detected by using a thickness gauge.
d) Laser scribing: performing unit cutting on the sensitive membrane and the substrate with the etching cavity by using a laser process; the energy density was set at 8.639J/cm2The repetition frequency is 25KHz, the scanning speed is 0.1mm/s, the scanning frequency is 2 times, and the edge of the etched micro-channel is the most flat;
e) hot-pressing bonding: removing the pollution generated by ablation of a silicon carbide material in the laser scribing process, attracting cleaned and surface-activated silicon carbide wafers in a methanol solution through the surface interaction force between the wafers through pre-bonding to form a spontaneous bond with weaker strength, and performing hot-press bonding on the pre-bonded silicon carbide sensitive structure by using a one-way hot-press furnace; and (3) putting the pre-bonded wafer into a hot-pressing bonding furnace with a customized graphite clamp, adjusting the heating rate by controlling the heating power, applying pressure to the wafer through a hydraulic pump and a pressure head displacement control system after the required temperature is reached, and finally unloading the pressure to cool the temperature in the furnace to room temperature through a water cooling system to finish the direct bonding of the silicon carbide wafer.
Bonding a sensitive membrane and a wafer with an etching cavity by adopting a silicon carbide direct bonding method to form a sealed cavity which is the key of the sensor used at ultrahigh temperature, wherein the direct bonding specifically comprises surface treatment, pre-bonding and hot-press bonding; the surface treatment comprises chemical wet cleaning and plasma activation, wherein the silicon carbide wafer is firstly put into a mixture (7: 3) of concentrated sulfuric acid and 30% hydrogen peroxide to remove heavy organic contamination on the surface of the wafer, then put into a mixed solution of ammonia water, hydrogen peroxide and water to remove surface particle contamination, and finally put into a mixed solution of sulfuric acid and hydrogen peroxide to carry out surface hydrophilic treatmentAfter treatment, drying, wherein ammonia water can enable the surface of the wafer to generate a hydrophilic atmosphere, and hydrophilic soaking and plasma activated surface treatment enhance the hydrophilicity of the surface of the wafer so that the pre-bonding between the wafers is easier; before pre-bonding, performing surface plasma treatment on a wafer to enhance the surface energy of a bonding surface, putting the wafer into a plasma system, introducing oxygen to sputter the surface for 3min, and quickly putting a wafer into a methanol solution rich in hydroxyl groups for pre-bonding after activating the bonding surface by using the plasma; the high-temperature hot-pressing bonding furnace adopted in the method is one-way pressure-applying vacuum bonding equipment, the wafer which is subjected to pre-bonding is placed into the hot-pressing bonding furnace with a customized graphite clamp, the temperature in the furnace is increased to 200 ℃ at the speed of 10 ℃/min and is kept for 40 minutes, and then the furnace is vacuumized to 5 x 10-3After Pa, the temperature is raised to 1000 ℃ at the acceleration rate of 20 ℃/min, 3MPa pressure is applied to the wafer through a hydraulic pump and a pressure head displacement control system to maintain for 1 hour, and finally the pressure is unloaded to cool the temperature in the furnace to the room temperature, thus completing direct bonding;
f) packaging a sensor: and packaging the silicon carbide sensitive mechanism subjected to thermal compression bonding by using a silicon carbide ceramic packaging clamp. The expansion coefficient of the silicon carbide ceramic is basically the same as that of the silicon carbide material, and the silicon carbide ceramic is suitable for working in an ultrahigh-temperature environment; the whole packaging structure comprises a pressing cover, a connecting sleeve and a rear-end base column, wherein a sensitive result is placed in the connecting sleeve and then is fixed by screwing the pressing cover through threads, and the rear-end base column is provided with a through hole matched with the quartz sleeve and is connected in a screwing mode; and finally, bonding the joint of the quartz sleeve and the rear end pillar by using high-temperature glue.
The optical fiber Fabry-Perot high-temperature pressure sensor is prepared by adopting the silicon carbide material, the sensitive devices in the sensor comprise the sensitive diaphragm 3 and the wafer 2 with the etching cavity, and the sensitive diaphragm 3 and the wafer 3 with the etching cavity are directly bonded by adopting the silicon carbide material to form the Fabry-Perot cavity, so that the air tightness is good, the bonding strength is high, and the sensitivity of the sensor is still high under the high-temperature test of 600 ℃; the production efficiency of the device is improved, and the production cost is reduced.
The invention is not limited to the above embodiment, and on the basis of the technical scheme disclosed by the invention, the production efficiency of the device is improved, and the production cost is reduced.
Those skilled in the art can make various alterations and modifications to the technical features of the invention without creative efforts based on the technical content disclosed, and the alterations and modifications are all within the protection scope of the invention.
Claims (8)
1. A manufacturing method of a silicon carbide high-temperature pressure sensor based on an optical fiber Fabry-Perot method is characterized by comprising the following steps:
a) selecting a 4H-SiC wafer as a manufacturing material of the silicon carbide sensitive structure; the silicon carbide sensitive structure comprises a sensitive membrane and a wafer with an etching cavity;
b) manufacturing a wafer with an etching cavity:
b1) glue homogenizing: selecting a silicon surface of the silicon carbide to carry out a photoetching process, immediately placing the wafer on a heating table to carry out soft baking after the glue is homogenized, and carrying out photoetching after the temperature of the wafer is cooled to room temperature after the soft baking is finished;
b2) photoetching: aligning the mask plate with the wafer, turning on an ultraviolet light source to enable ultraviolet light to penetrate through the mask plate to expose photoresist on the surface of the wafer, and developing the wafer after exposure is finished;
b3) magnetron sputtering: preparing an adhesion layer and a seed layer by adopting a magnetron sputtering process, wherein metals are Cr and Cu, the Cr is used as the adhesion layer between the outer layer metal and the wafer, and the Cu is used as the seed layer of the subsequent electroplating process;
b4) stripping: immersing the wafer into an acetone solution, carrying out ultrasonic stripping, and removing the photoresist and the metal on the surface of the photoresist;
b5) electroplating: selecting metal Ni as etched mask metal, and preparing a metal hard mask by using an electroplating process;
b6) etching the cavity by adopting an etching process: placing the electroplated wafer into an etching machine for etching for a period of time, taking out the electroplated wafer, measuring the depth by using a step instrument, placing the silicon carbide wafer into the etching machine for secondary etching, taking out the silicon carbide wafer, and measuring the depth by using the step instrument;
b7) removing metals: after the plasma etching process is finished, removing the metal mask by respectively adopting Ni corrosive liquid, Cu corrosive liquid and Cr corrosive liquid;
c) manufacturing a sensitive membrane:
c1) chemical grinding, thinning and polishing by CMP: thinning the silicon carbide wafer to the required thickness by using a thinning machine, and then polishing the wafer by using a polishing machine to eliminate the residual stress on the surface of the wafer in the thinning process;
d) laser scribing: performing unit cutting on the sensitive membrane and the substrate with the etching cavity by using a laser process;
e) and (3) hot-pressing bonding: removing the pollution generated by ablation of a silicon carbide material in the laser scribing process, attracting cleaned and surface-activated silicon carbide wafers in a methanol solution through the surface interaction force between the wafers through pre-bonding to form a spontaneous bond with weaker strength, and performing hot-press bonding on the pre-bonded silicon carbide sensitive structure by using a one-way hot-press furnace;
f) packaging a sensor: and packaging the silicon carbide sensitive mechanism subjected to thermal compression bonding by using a silicon carbide ceramic packaging clamp.
2. The method for manufacturing the silicon carbide high-temperature pressure sensor based on the fiber Fabry-Perot method according to claim 1, wherein in the etching process in the step b 6), an inductively coupled plasma etching device in dry etching is used for etching the silicon carbide material.
3. The method for manufacturing the fiber-Fabry-Perot-based silicon carbide high-temperature pressure sensor according to claim 1, wherein the step c1) specifically comprises the following steps: 1) sheet sticking: adhering the wafer on a glass substrate, and polishing the C surface of the silicon carbide wafer; 2) before thinning and polishing, the grinding disc is required to be repaired, the thinning grinding disc is repaired by using alumina grinding fluid, and the polishing grinding disc is repaired by using a disc repairing block and deionized water; 3) thinning: firstly, carrying out coarse thinning by using a large-particle-size boron carbide grinding fluid, and then carrying out fine thinning by using a small-particle-size grinding fluid; 4) polishing: polishing by adopting a grinding disc with the surface consisting of a plurality of polyurethane polishing pads, wherein the polishing solution adopts CS series polishing solution; 5) measurement: after the thinning and polishing process is completed, the silicon carbide wafer is taken down from the glass substrate for cleaning, and the wafer is detected by using a thickness gauge.
4. The manufacturing method of the optical fiber Fabry-Perot-based silicon carbide high-temperature pressure sensor according to claim 1, wherein the thermocompression bonding in step e) specifically comprises: and (3) putting the pre-bonded wafer into a hot-pressing bonding furnace with a customized graphite clamp, adjusting the heating rate by controlling the heating power, applying pressure to the wafer through a hydraulic pump and a pressure head displacement control system after the required temperature is reached, and finally unloading the pressure to cool the temperature in the furnace to room temperature through a water cooling system to finish the direct bonding of the silicon carbide wafer.
5. The silicon carbide high-temperature pressure sensor based on the fiber Fabry-Perot is prepared according to the method of claim 1, and is characterized by comprising a silicon carbide sensitive structure, a silicon carbide ceramic packaging clamp, a quartz sleeve and an optical fiber, wherein the silicon carbide ceramic packaging clamp comprises a pressing cover, a connecting sleeve and a rear-end base pillar with a hole, the sensitive structure is placed in the connecting sleeve and is fixed through the pressing cover, the quartz sleeve is fixed in the rear-end base pillar, and the optical fiber is inserted in the quartz sleeve; the silicon carbide sensitive structure comprises a sensitive membrane and a wafer with an etching cavity, wherein the sensitive membrane and the wafer with the etching cavity are bonded to form a Fabry-Perot cavity.
6. The fiber-Fabry-Perot based silicon carbide high temperature pressure sensor according to claim 5, wherein the sensing diaphragm is circular in shape.
7. The silicon carbide high-temperature pressure sensor based on the fiber Fabry-Perot is characterized in that a through hole is formed in the pressing cover, external threads are formed in the periphery of the pressing cover, the connecting sleeve is provided with internal threads, and the pressing cover is screwed to fix the silicon carbide sensitive structure through threads.
8. The silicon carbide high-temperature pressure sensor based on the fiber Fabry-Perot is characterized in that the rear-end base column with the hole is provided with a thread, and is fixedly connected with the connecting sleeve in a thread screwing mode.
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