CN110780090A - Piezoresistive acceleration sensor based on silicon carbide material and manufacturing method thereof - Google Patents

Piezoresistive acceleration sensor based on silicon carbide material and manufacturing method thereof Download PDF

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Publication number
CN110780090A
CN110780090A CN201911212178.1A CN201911212178A CN110780090A CN 110780090 A CN110780090 A CN 110780090A CN 201911212178 A CN201911212178 A CN 201911212178A CN 110780090 A CN110780090 A CN 110780090A
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China
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silicon carbide
acceleration sensor
etching
photoetching
piezoresistive
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CN201911212178.1A
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CN110780090B (en
Inventor
徐天彤
陶智
李海旺
翟彦欣
桂英轩
曹晓达
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Beihang University
Beijing University of Aeronautics and Astronautics
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Beijing University of Aeronautics and Astronautics
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01PMEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P15/00Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
    • G01P15/02Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses
    • G01P15/08Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values
    • G01P15/12Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values by alteration of electrical resistance
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B81MICROSTRUCTURAL TECHNOLOGY
    • B81CPROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
    • B81C1/00Manufacture or treatment of devices or systems in or on a substrate
    • B81C1/00015Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems
    • B81C1/00134Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems comprising flexible or deformable structures
    • B81C1/0015Cantilevers
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B81MICROSTRUCTURAL TECHNOLOGY
    • B81CPROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
    • B81C1/00Manufacture or treatment of devices or systems in or on a substrate
    • B81C1/00015Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems
    • B81C1/00261Processes for packaging MEMS devices
    • B81C1/00269Bonding of solid lids or wafers to the substrate
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B81MICROSTRUCTURAL TECHNOLOGY
    • B81BMICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
    • B81B2201/00Specific applications of microelectromechanical systems
    • B81B2201/02Sensors
    • B81B2201/0228Inertial sensors
    • B81B2201/0235Accelerometers

Abstract

The utility model provides a piezo-resistive acceleration sensor based on carborundum material, based on the piezoresistive effect, adopt the design of two cantilever beams, resistance strip and the circuit arrangement position design that resistance changes along with the stress form the Wheatstone bridge. The sensitive element substrate is silicon carbide, the resistor is a doped silicon carbide material, and the surface wiring material is gold. And the packaging design of the whole device is provided, and the packaging design comprises a glass upper cover and a bottom silicon-based tube shell used for limiting, and ceramic tube shell packaging. The silicon-based inner shell substrate obtained by adopting a silicon processing technology can provide accurate vibration margin and protection limit. Through a gold wire ball bonding process, input and output signals of four pads of the sensor chip are led to four metal pins on the side edge of the metal tube shell, and 50-micrometer gold wire signal transmission is adopted, so that the stability of signal transmission and the high-temperature safety of the chip are ensured. The disclosure also provides a manufacturing method of the piezoresistive acceleration sensor based on the silicon carbide material.

Description

Piezoresistive acceleration sensor based on silicon carbide material and manufacturing method thereof
Technical Field
The disclosure relates to the technical field of electronic elements, in particular to a piezoresistive acceleration sensor based on a silicon carbide material and a manufacturing method thereof.
Background
To date, MEMS acceleration sensors have taken up a considerable percentage of the market and are widely used. For example, the MEMS acceleration sensor which is independently researched and manufactured by national Qingdao Intelligent Teng company completes the product manufacture through MEMS process flows such as etching, packaging and the like, realizes the bias stability of 0.24-6, the working temperature of-40-125 ℃ and the measuring range of +/-2- +/-50 g, and has been successfully used for aerospace craft. Meanwhile, the doped silicon carbide material with excellent high-temperature performance is used as a sensitive element substrate, so that the sensor sensitive element with better working performance in a high-temperature state can be obtained.
The vast majority of materials that can be currently processed by MEMS processes undergo property changes, even failure, in high temperature environments, thereby limiting the operational tolerance of the MEMS devices to ambient temperatures. The sensor has extremely high requirements on the working performance of a sensitive element, so that acceleration detection in a high-temperature environment is always a very challenging problem in the field of sensors, and in addition, in the MEMS processing process flow, the processing and the manufacturing method of the silicon carbide material are also a main problem for limiting the development of components of the silicon carbide substrate.
Disclosure of Invention
In order to solve the technical problems in the prior art, the embodiments of the present disclosure provide a method and an apparatus for inferring a numerical control machining state based on real-time data and STEP-NC data, the method is completed by providing an MEMS acceleration sensor capable of working in a high temperature environment, and aims to solve the difficulty in machining silicon carbide materials and provide a sensor sensitive element capable of working normally at a high temperature.
In a first aspect, embodiments of the present disclosure provide a piezoresistive acceleration sensor based on silicon carbide material, including: sensitive element substrate, resistor and surface wiring material; the sensitive element substrate is silicon carbide, the resistor is a component formed by silicon carbide materials doped with a preset threshold degree, and the surface wiring material is gold.
In one embodiment, the piezoresistive acceleration sensor further comprises: a glass upper cover, a bottom silicon-based substrate and a ceramic tube shell.
In one embodiment, the piezoresistive acceleration sensor further comprises: a silicon-based inner package substrate configured to provide a vibration margin of a predetermined precision and a protection limit.
In one embodiment, the piezoresistive acceleration sensor is based on piezoresistive effect and is implemented by adopting a double-cantilever beam design.
In a second aspect, the disclosed embodiments provide a method for manufacturing a piezoresistive acceleration sensor based on a silicon carbide material, including the following steps: carrying out resistance photoetching on the epitaxial layer of the SiC wafer by using a front dry etching machine, and forming a resistance pattern; using SiO 2Protecting the isolation piece, and etching the window at a preset position to finish the medium hole photoetching operation; etching the front surface of the hollow part of the component by a preset depth in a front surface deep groove photoetching mode, and controlling the position thickness of the cantilever beam where the resistance strip is located by the preset depth; SiO in the resistor strip 2Ohmic contact is formed at the position of the window through lift-off technology; manufacturing the component into pad by a metal wiring photoetching method, and forming metal interconnection with the ohmic contact; the back thinning of the metal interconnection part is completed through cleaning operation, front glue homogenizing operation and front bonding operation in sequence; and then sequentially carrying out sputtering operation, photoetching operation, developing operation, film hardening operation, priming film operation, metal corrosion operation and etching operation on the processed metal interconnection part to finish back hole photoetching operation.
In one embodiment, the method further comprises the following steps: preparing a mask of silicon carbide; the mask for preparing the silicon carbide comprises the following steps: and processing the silicon carbide and carrying out alignment operation on a plurality of mask plates.
In one embodiment, the method further comprises the following steps: and the number of times of finishing back thinning by sequentially carrying out cleaning operation, front glue homogenizing operation and front bonding operation on the metal interconnection part is twice.
The invention provides a piezoresistive acceleration sensor based on silicon carbide materials and a manufacturing method thereof. The sensitive element substrate is silicon carbide, the resistor is made of highly doped silicon carbide material, and the surface wiring material is gold. Furthermore, the packaging design scheme of the whole device is provided, and comprises a glass upper cover used as a limit, a silicon-based tube shell at the bottom and a ceramic tube shell packaging design. By adopting a silicon processing technology, the high-precision silicon-based inner shell substrate can provide accurate vibration margin and protection limit. Through a gold wire ball bonding process, input and output signals of four pads of the sensor chip are led to four metal pins on the side edge of the metal tube shell, and a 50-micrometer gold wire is adopted for signal transmission, so that the stability of signal transmission and the high-temperature safety of the chip are ensured.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings needed to be used in the description of the embodiments are briefly introduced as follows:
FIG. 1 is a schematic flow chart illustrating a method for manufacturing a piezoresistive acceleration sensor based on silicon carbide material according to an embodiment of the present invention;
FIGS. 2(a) - (c) are schematic diagrams illustrating a top view and a layout of a SiC acceleration sensor in a method for manufacturing a SiC-based piezoresistive acceleration sensor according to an embodiment of the present invention;
FIG. 3 is a schematic cross-sectional view of a SiC acceleration sensor implemented in a method for manufacturing a SiC-based piezoresistive acceleration sensor according to an embodiment of the present invention;
FIG. 4 is a three-dimensional schematic diagram of a bottom silicon-based package for implementing a method of fabricating a piezoresistive acceleration sensor based on silicon carbide material, according to an embodiment of the present invention;
FIG. 5 is a schematic diagram of a ceramic package in an embodiment of the present invention for implementing a method for manufacturing a piezoresistive acceleration sensor based on silicon carbide material;
FIG. 6 is a schematic diagram of a silicon carbide processing mask in an embodiment of the present invention for implementing a method for manufacturing a piezoresistive acceleration sensor based on silicon carbide material;
FIG. 7 is a schematic illustration of a silicon carbide processing reticle overlay in a method of implementing a silicon carbide material based piezoresistive acceleration sensor fabrication in accordance with an embodiment of the present invention;
FIG. 8 is a schematic illustration of a silicon carbide process flow for implementing a method of fabricating a piezoresistive silicon carbide material-based acceleration sensor in accordance with an embodiment of the present invention;
FIG. 9 is a schematic illustration of a silicon carbide resistive reticle embodied in a method of fabricating a silicon carbide based piezoresistive acceleration sensor in accordance with an embodiment of the present invention;
FIG. 10 is a schematic view of a silicon carbide resistor processing flow in a method of fabricating a piezoresistive silicon carbide material-based acceleration sensor in accordance with an embodiment of the present invention;
fig. 11 is a schematic diagram of SEM observation of silicon carbide resistive etching patterns in a method of manufacturing a piezoresistive acceleration sensor based on silicon carbide material according to an embodiment of the present invention;
FIG. 12 is a schematic view of an insulating dielectric hole photolithography plate used in implementing a method of fabricating a piezoresistive acceleration sensor based on silicon carbide material according to an embodiment of the present invention;
FIG. 13 is a schematic illustration of dielectric hole lithography in a method of fabricating a piezoresistive acceleration sensor based on silicon carbide material, in accordance with an embodiment of the present invention;
FIG. 14 is a schematic view of an optical microscope after etching an insulating dielectric hole in a method for manufacturing a piezoresistive acceleration sensor based on silicon carbide material according to an embodiment of the present invention;
FIG. 15 is a schematic diagram of a front deep trench etching reticle used in a method for manufacturing a piezoresistive acceleration sensor based on silicon carbide material according to an embodiment of the present invention;
FIG. 16 is a schematic diagram illustrating a front deep trench etching process in a method for manufacturing a piezoresistive acceleration sensor based on silicon carbide material according to an embodiment of the present invention;
fig. 17 is a schematic view of an optical microscope observation after etching a front deep trench in a method for manufacturing a piezoresistive acceleration sensor based on silicon carbide according to an embodiment of the present invention;
FIG. 18 is a schematic view of an ohmic contact photolithography plate for implementing a method of fabricating a piezoresistive acceleration sensor based on silicon carbide material according to an embodiment of the present invention;
FIG. 19 is a schematic illustration of ohmic contact lithography for implementing a method of fabricating a piezoresistive acceleration sensor based on silicon carbide material, in accordance with an embodiment of the present invention;
FIG. 20 is a schematic view of a microscope observing ohmic contact patterns in a method of fabricating a piezoresistive acceleration sensor based on silicon carbide material according to an embodiment of the present invention;
FIG. 21 is a schematic view of an optical microscope observing ohmic contact patterns in a method of fabricating a piezoresistive acceleration sensor based on silicon carbide material according to an embodiment of the present invention;
FIG. 22 is a schematic view of an SEM observed ohmic contact pattern in a method of fabricating a piezoresistive acceleration sensor based on silicon carbide material according to an embodiment of the present invention;
FIG. 23 is a schematic diagram illustrating a metal wiring pattern after photolithography observed by an optical microscope in a method for manufacturing a piezoresistive acceleration sensor based on silicon carbide, according to an embodiment of the present invention;
FIG. 24 is a schematic diagram illustrating a stripped metal wire observed by an optical microscope in a method for manufacturing a piezoresistive acceleration sensor based on silicon carbide, according to an embodiment of the present invention;
fig. 25 is a simplified cross-sectional view illustrating a cantilever beam process in a method for manufacturing a piezoresistive acceleration sensor based on silicon carbide according to an embodiment of the present invention.
Detailed Description
The present application will now be described in further detail with reference to the accompanying drawings and examples.
In the following description, the terms "first" and "second" are used for descriptive purposes only and are not intended to indicate or imply relative importance. The following description provides embodiments of the disclosure, which may be combined or substituted for various embodiments, and this application is therefore intended to cover all possible combinations of the same and/or different embodiments described. Thus, if one embodiment includes feature A, B, C and another embodiment includes feature B, D, then this application should also be considered to include an embodiment that includes one or more of all other possible combinations of A, B, C, D, even though this embodiment may not be explicitly recited in text below.
In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of a piezoresistive acceleration sensor based on silicon carbide material and a manufacturing method thereof according to the present invention are described in further detail below by way of examples and with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
In one embodiment, a piezoresistive acceleration sensor based on silicon carbide material is disclosed. Specifically, the piezoresistive acceleration sensor includes: sensitive element substrate, resistor and surface wiring material; the sensitive element substrate is silicon carbide, the resistor is a component formed by silicon carbide materials doped with a preset threshold degree, and the surface wiring material is gold. In addition, it should be noted that the piezoresistive acceleration sensor further includes: glass upper cover, bottom silicon substrate tube shell and ceramic tube shell.
Further, in one embodiment, the piezoresistive acceleration sensor further comprises: a silicon-based inner package substrate configured to provide a vibration margin of a predetermined precision and a protection limit. Further, in one embodiment, the piezoresistive acceleration sensor is based on piezoresistive effect, and is implemented by adopting a double cantilever beam design.
As shown in fig. 1, a schematic flow chart of a method for manufacturing a piezoresistive acceleration sensor based on silicon carbide material in an embodiment specifically includes the following steps:
and 101, performing resistance photoetching on the epitaxial layer of the SiC wafer by using a front dry etching machine, and forming a resistance pattern.
Step 102, using SiO 2And protecting the isolation piece, and etching the window at a preset position to finish the photoetching operation of the dielectric hole.
And 103, etching the front surface of the hollow part of the component by a preset depth in a front surface deep groove photoetching mode, and controlling the position thickness of the cantilever beam where the resistance strip is located by the preset depth.
104, SiO the resistance strip 2The window locations are formed in ohmic contact by a lift-off process.
And 105, manufacturing the component into a pad by a metal wiring photoetching method, and forming metal interconnection with the ohmic contact.
And 106, finishing back thinning of the metal interconnection part by sequentially performing cleaning operation, front glue spreading operation and front bonding operation.
And step 107, sequentially performing sputtering operation, photoetching operation, developing operation, film hardening operation, bottom film coating operation, metal corrosion operation and etching operation on the processed metal interconnection part to finish back hole photoetching operation.
Further, in one embodiment, the method further comprises: and preparing a mask of silicon carbide. The preparation of the mask of the silicon carbide comprises the following steps: and processing the silicon carbide and carrying out alignment operation on a plurality of mask plates.
In addition, in an embodiment, it should be further noted that the number of times of completing the back thinning of the metal interconnection portion through the cleaning operation, the front glue spreading operation, and the front bonding operation in sequence is two.
In order to more clearly understand and apply the manufacturing method of the piezoresistive acceleration sensor based on silicon carbide material proposed by the present disclosure, the following example is made. It should be noted that the protection scope of the present disclosure is not limited to the following examples.
In particular, as shown in fig. 2 to fig. 25, the piezoresistive acceleration sensor core sensing element designed by the present disclosure is based on piezoresistive effect, and adopts a double cantilever beam design, as shown in fig. 2(a) - (c), and arranges the resistive strips and lines with resistance varying with stress, as shown in fig. 2(a) - (c), to form a wheatstone bridge. In addition, as shown in fig. 3, the sensing element substrate is silicon carbide, the resistor strip is formed by sequentially doping silicon carbide with heavy N and low P, and the wire is made of gold.
Further, the present disclosure proposes the packaging design of the whole device, including the glass top cap and the bottom silicon-based package used as the limit, and the ceramic package design, as shown in fig. 4 and 5. By adopting a silicon processing technology, the high-precision silicon-based inner shell substrate can provide accurate vibration margin and protection limit. Through a gold wire ball bonding process, input and output signals of four pads of the sensor chip are led to four metal pins on the side edge of the metal tube shell, and a 50-micrometer gold wire is adopted for signal transmission, so that the stability of signal transmission and the high-temperature safety of the chip are ensured.
Furthermore, the present disclosure also discloses a method for manufacturing a core sensitive element of an acceleration sensor based on silicon carbide, which includes: resistance photoetching, medium hole photoetching, front deep groove photoetching, ohmic contact photoetching, metal wiring photoetching, back surface thinning and back hole photoetching are carried out for six MASK thinning times.
Firstly, preparing a high-temperature-resistant silicon carbide acceleration sensor early-stage graph and processing, and preparing a silicon carbide mask as shown in figure 6. Fig. 7 is a schematic diagram after 6 masks are aligned; a schematic of the silicon carbide process flow is shown in fig. 8. Further explanation is needed for the machining accuracy: the front alignment precision is not less than 2um, and the back alignment precision is not less than 5 um; the pattern line width error is not more than 2 um; the deposition thickness of the film can be adjusted along with the processing method on the basis of outputting an electric signal, and no requirement is made on errors; the etching depth error is not more than 2um, the verticality is not required, and the depth is as close as possible to 90 degrees. Furthermore, the requirements regarding dicing the package are: the chip can be independently packaged, and a voltage signal can be output at a chip pin.
Specifically, the main objective of the resistance lithography is to etch the epitaxial layer of the SiC material on the front side and form a resistance pattern. The photolithography plate and the simple flow chart are shown in fig. 9-11. Specifically, a dry etching machine is used to etch the epitaxial layer of the SiC wafer, so as to obtain a pattern with a perfect morphology meeting the process requirements, as shown in fig. 11.
The main purpose of the process stage of dielectric hole lithography is to use SiO2 to protect the isolation device and etch the window at the required position for subsequent process development, and the photolithography mask and the simplified flow chart are shown in fig. 12-14. Specifically, SiO2 is etched by using a photolithography etcher to obtain a pattern meeting the process requirements, as shown in fig. 14.
The main purpose of the process stage of the front deep groove photoetching is to etch the front of the hollow part of the device to a certain depth, and the thickness of the position of the cantilever beam where the resistance strip is located is controlled by the depth. The photolithography plate and the simple flow chart are shown in fig. 15-17. In addition, the main purpose of the ohmic contact photoetching process stage is to form ohmic contact in lift-off process at the window position of the SiO2 of the resistor strip. The photolithography plate and the simple flow chart are shown in fig. 18-22. Further, the main purpose of the gold tertiary wiring lithography process stage is to make pads and form metal interconnects with ohmic contacts. The specific flow chart is shown in fig. 23-24.
Furthermore, the back thinning process mainly comprises cleaning, front glue spreading protection and front bonding. In particular, with respect to the cleaning operation, i.e., before the process is performed, it is necessary to ensure the cleanliness of the front and back surfaces of the material. The front surface process of the SiC wafer is finished, and the impurity contamination of the residual front surface can cause the front surface device to be damaged in the subsequent process and can directly influence the subsequent back surface exposure process; the back of the wafer is the thinning surface required by the process, and larger particle impurities are prevented from being contaminated so as to prevent the subsequent thinning effect from being influenced. And cleaning the SiC through the processes of NMP soaking, ethanol washing and deionized water washing. The cleanliness of the material is ensured.
Regarding front side glue spreading protection, namely before a bonding process is carried out, glue spreading protection needs to be carried out on devices on the front side of the SiC wafer. When low-temperature wax (the melting point is about 85 degrees) is used for bonding, the photoresist with moderate viscosity can be simply selected for the photoresist homogenizing protection. And when the front side of the SiC wafer is coated, the floccule is prevented from being polluted. The glue homogenizing table is required to be cleaned in time after glue homogenizing, contamination is prevented, meanwhile, the corners of the back of the wafer are required to be cleaned, and the glue homogenizing uniformity of the wafer is guaranteed. And after the glue homogenizing is finished, placing the SiC wafer on a hot table for baking, and after cooling, using a thickness tester to perform in-plane 5-point thickness measurement. And when the thickness measurement difference of the 5 points on the front surface is less than 10um, the next bonding process can be carried out.
Regarding the front bonding, a sapphire support with the uniformity conforming to the process is selected, and the SiC wafer and the sapphire support are bonded by using high-temperature wax. After bonding, in-plane 5 point thickness measurements were made using a thickness tester. And the next process can be continued under the condition that the thickness measurement difference of 5 points on the front surface is less than 10 um. And continuously bonding the back surface of the sapphire support with the special glass support, and measuring the thickness of the front surface of the wafer again after bonding.
In addition, it should be noted that the present disclosure provides a method for manufacturing a piezoresistive acceleration sensor based on a silicon carbide material, including: resistance photoetching, medium hole photoetching, front deep groove photoetching, ohmic contact photoetching, metal wiring photoetching, back surface thinning and back hole photoetching are carried out for six MASK thinning times. Specifically, the back thinning is to treat that the thinning face of the SiC wafer is upwards placed on a clamp, after the back glass support is confirmed to be vacuum-absorbed, proper grinding liquid is selected, and the wafer thinning is started by using a thinning machine. After a plurality of tests and adjustments, the process ensures that the back of the SiC wafer is thinned, the structure of the wafer is intact, and no obvious scratch is generated. And a solid foundation is laid for the development of the subsequent back hole etching process.
Further, the back hole lithography process stages include sputtering, photolithography, development, hardening, priming, etching metal, and etching. Specifically, regarding the sputtering process, namely, through the research on the etching of the SiC deep groove in the front part of the processing process, the deep groove etching experience is mainly used during the SiC back etching in the process, and the process is properly adjusted by combining the characteristics of the back etching, so as to achieve the expected effect. In the process, metal is still selected as a mask for SiC etching, and KS-400 is used for sputtering according to the SiC/metal etching selection ratio which is researched and completed by the previous process to obtain the mask required by the current back etching.
In addition, regarding the photolithography process, i.e., in accordance with the front deep trench etching process, the metal mask is patterned using the photolithography process. Glue homogenizing: the method is characterized in that a layer of uniform photoresist is spin-coated on a SiC wafer sputtered with metal, and the SiC wafer is different from a front etching process in that the wafer is a 1/4-size 4-inch wafer, is bonded, thinned and sputtered and is still fixed on a sapphire support, the internal stress of the wafer is changed to a certain extent, and the wafer is carefully and strictly centered during the spin-coating process so as to prevent the occurrence of abnormal phenomena such as cracking, chipping and the like during the high-speed spin of the spin-coating process. Pre-baking: and placing the SiC wafer with the photoresist well homogenized on a hot plate for baking. Exposure: and (3) exposing the SiC wafer by using a photoetching machine, etching the process parameters and the front deep groove, and reducing the pressure of the photoetching plate on the wafer by adopting contact exposure to prevent the wafer from being crushed. In addition, the process is double-sided exposure, the alignment mark is arranged on the SiC wafer on one side of the back surface of the sapphire support, and the multilayer structure of the high-temperature wax can be observed only through the transparent sapphire support. This requires front end processing to ensure adequate cleaning of the front side of the SiC wafer prior to bonding. The impurities may block the alignment mark, resulting in the abnormality of alignment difficulty, exposure distortion, etc.
Further, regarding the developing process, namely developing the SiC after the exposure is finished by using the developing solution, the process parameters are the same as those of the etching of the front deep groove, and it should be noted that the thinned SiC wafer is relatively fragile, and the operation should be noted to prevent the chipping. Particularly when nitrogen is used to purge the wafer, the nitrogen gun pressure should be properly controlled. In addition, regarding the film hardening process, namely after the photoresist pattern is transferred, the SiC wafer is placed on a hot plate for film hardening, and the technological parameters are the same as those of the etching of the front deep groove. Compared with the front deep groove etching, the back etching adopts a thicker metal mask, the etching time is 1, 5 times of that of the front etching, the lateral underetching is easier to generate, and the film hardening time can be properly increased or baking by adopting an oven is adopted for hardening. In addition, regarding the bottom film coating process, namely Trymax is used for carrying out the bottom film coating process on the SiC wafer, and the process parameters are the same as those of the front deep groove etching.
Furthermore, regarding the metal etching process, namely after the photoetching process is finished, the wet etching process is carried out on the metal mask of the SiC wafer, and the process parameters are basically the same as those of the front deep groove etching. In addition, regarding the etching process, namely etching SiC by using an S dry etching machine, the etching menu is the same as the etching of the front deep groove. After a plurality of tests, the back etching of the process is carried out by using a front deep groove etching process menu. The deep trench pattern can be stably obtained. The difference between the front deep groove etching process and the back deep groove etching process is that the back etching needs to judge and control the etching end point more accurately. The etching flow is shown in fig. 25. As shown in fig. 25, the device forms a zigzag structure by deep trench etching on the front surface and hole etching on the back surface, and the middle part of the device is supported by only 2 cantilever beams. The thickness of the cantilever beam structure is determined by the etching depth of the front surface and the etching depth of the back surface. How to control the back side etch depth is critical to the process. And when the etching speed is reduced when the etching end point is approached, the thickness of the cantilever beam can be controlled more accurately.
In summary, the method for manufacturing the piezoresistive acceleration sensor based on the silicon carbide substrate can detect the vibration condition and the motion acceleration data of the measured object in real time, and the silicon carbide substrate sensitive element can endure extremely high temperature and has a wide measuring range. The method can realize the complete processing process flow of the silicon carbide substrate material, reasonably solve the process difficulties of etching, ohmic contact, wire bonding and the like in the processing process, and provide accurate process information for the processing and manufacturing of the acceleration sensor of the piezoresistive silicon carbide substrate material.
The invention provides a piezoresistive acceleration sensor based on silicon carbide materials and a manufacturing method thereof. The sensitive element substrate is silicon carbide, the resistor is a doped silicon carbide material, and the surface wiring material is gold. Furthermore, the packaging design scheme of the whole device is provided, and comprises a glass upper cover used as a limit, a silicon-based tube shell at the bottom and a ceramic tube shell packaging design. By adopting a silicon processing technology, the high-precision silicon-based inner shell substrate can provide accurate vibration margin and protection limit. Through a gold wire ball bonding process, input and output signals of four pads of the sensor chip are led to four metal pins on the side edge of the metal tube shell, and a 50-micrometer gold wire is adopted for signal transmission, so that the stability of signal transmission and the high-temperature safety of the chip are ensured.
An embodiment of the present invention further provides a computer-readable storage medium, where a computer program is stored on the computer-readable storage medium, and the computer program is executed by the processor in fig. 1.
The embodiment of the invention also provides a computer program product containing the instruction. Which when run on a computer causes the computer to perform the method of fig. 1 described above.
It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by a computer program, which can be stored in a computer-readable storage medium, and when executed, can include the processes of the embodiments of the methods described above. The storage medium may be a magnetic disk, an optical disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), or the like.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
The foregoing describes the general principles of the present disclosure in conjunction with specific embodiments, however, it is noted that the advantages, effects, etc. mentioned in the present disclosure are merely examples and are not limiting, and they should not be considered essential to the various embodiments of the present disclosure. Furthermore, the foregoing disclosure of specific details is for the purpose of illustration and description and is not intended to be limiting, since the disclosure is not intended to be limited to the specific details so described.
The block diagrams of devices, apparatuses, systems referred to in this disclosure are only given as illustrative examples and are not intended to require or imply that the connections, arrangements, configurations, etc. must be made in the manner shown in the block diagrams. These devices, apparatuses, devices, systems may be connected, arranged, configured in any manner, as will be appreciated by those skilled in the art. Words such as "including," "comprising," "having," and the like are open-ended words that mean "including, but not limited to," and are used interchangeably therewith. The words "or" and "as used herein mean, and are used interchangeably with, the word" and/or, "unless the context clearly dictates otherwise. The word "such as" is used herein to mean, and is used interchangeably with, the phrase "such as but not limited to".
Also, as used herein, the use of "or" in a list of items beginning with "at least one" indicates a separate list, e.g., "A, B or at least one of C" means A or B or C, or AB or AC or BC, or ABC (i.e., A and B and C). Furthermore, the word "exemplary" does not mean that the described example is preferred or better than other examples.
The foregoing description has been presented for purposes of illustration and description. Furthermore, this description is not intended to limit embodiments of the disclosure to the form disclosed herein. While a number of example aspects and embodiments have been discussed above, those of skill in the art will recognize certain variations, modifications, alterations, additions and sub-combinations thereof.

Claims (7)

1. A piezoresistive acceleration sensor based on silicon carbide material, characterized in that it comprises: sensitive element substrate, resistor and surface wiring material; the sensitive element substrate is silicon carbide, the resistor is a component formed by silicon carbide materials doped with a preset threshold degree, and the surface wiring material is gold.
2. The silicon carbide material-based piezoresistive acceleration sensor according to claim 1, characterized in that it further comprises: a glass upper cover, a bottom silicon-based substrate and a ceramic tube shell.
3. The silicon carbide material-based piezoresistive acceleration sensor according to claim 1, characterized in that it further comprises: a silicon-based inner package substrate configured to provide a vibration margin of a predetermined precision and a protection limit.
4. The silicon carbide material-based piezoresistive acceleration sensor according to claim 1, characterized in that it is based on piezoresistive effect, done with a double cantilever beam design.
5. A manufacturing method of a piezoresistive acceleration sensor based on silicon carbide materials is characterized by comprising the following steps:
carrying out resistance photoetching on the epitaxial layer of the SiC wafer by using a front dry etching machine, and forming a resistance pattern;
using SiO 2Protecting the isolation piece, and etching the window at a preset position to finish the medium hole photoetching operation;
etching the front surface of the hollow part of the component by a preset depth in a front surface deep groove photoetching mode, and controlling the position thickness of the cantilever beam where the resistance strip is located by the preset depth;
SiO in the resistor strip 2Ohmic contact is formed at the position of the window through lift-off technology;
manufacturing the component into pad by a metal wiring photoetching method, and forming metal interconnection with the ohmic contact;
the back thinning of the metal interconnection part is completed through cleaning operation, front glue homogenizing operation and front bonding operation in sequence;
and then sequentially carrying out sputtering operation, photoetching operation, developing operation, film hardening operation, priming film operation, metal corrosion operation and etching operation on the processed metal interconnection part to finish back hole photoetching operation.
6. The method of manufacturing a piezoresistive acceleration sensor based on silicon carbide material according to claim 5, characterized in that it further comprises: and preparing a mask of silicon carbide.
7. The method of manufacturing a piezoresistive acceleration sensor based on silicon carbide material according to claim 5, characterized in that it further comprises: and the number of times of finishing back thinning by sequentially carrying out cleaning operation, front glue homogenizing operation and front bonding operation on the metal interconnection part is twice.
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Citations (5)

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Publication number Priority date Publication date Assignee Title
US20030008514A1 (en) * 2001-07-03 2003-01-09 Commissariat A L'energie Atomique Piezoresistive device and manufacturing processes of this device
CN104062462A (en) * 2014-06-13 2014-09-24 浙江工业大学 MEMS piezoresistive accelerated speed sensor and manufacturing method thereof
CN104062463A (en) * 2014-06-13 2014-09-24 浙江工业大学 Piezoresistive acceleration sensor and manufacturing method thereof
CN104237559A (en) * 2014-07-30 2014-12-24 昆山泰莱宏成传感技术有限公司 Ultrahigh accelerating impact sensor based on embedded microcolumn and preparing method of ultrahigh accelerating impact sensor
CN109444469A (en) * 2018-12-28 2019-03-08 西安交通大学 A kind of full silicon carbide MEMS triaxial accelerometer and its manufacturing method

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20030008514A1 (en) * 2001-07-03 2003-01-09 Commissariat A L'energie Atomique Piezoresistive device and manufacturing processes of this device
CN104062462A (en) * 2014-06-13 2014-09-24 浙江工业大学 MEMS piezoresistive accelerated speed sensor and manufacturing method thereof
CN104062463A (en) * 2014-06-13 2014-09-24 浙江工业大学 Piezoresistive acceleration sensor and manufacturing method thereof
CN104237559A (en) * 2014-07-30 2014-12-24 昆山泰莱宏成传感技术有限公司 Ultrahigh accelerating impact sensor based on embedded microcolumn and preparing method of ultrahigh accelerating impact sensor
CN109444469A (en) * 2018-12-28 2019-03-08 西安交通大学 A kind of full silicon carbide MEMS triaxial accelerometer and its manufacturing method

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