CN115655534A - Pressure sensor and method for manufacturing pressure sensor - Google Patents
Pressure sensor and method for manufacturing pressure sensor Download PDFInfo
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- CN115655534A CN115655534A CN202211351877.6A CN202211351877A CN115655534A CN 115655534 A CN115655534 A CN 115655534A CN 202211351877 A CN202211351877 A CN 202211351877A CN 115655534 A CN115655534 A CN 115655534A
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Abstract
The invention provides a pressure sensor and a manufacturing method thereof, wherein the pressure sensor comprises a base body, a first bonding pad and a second bonding pad which are arranged on the base body, a capacitor is arranged on the base body, the capacitor comprises a fixed pole plate and an induction pole plate which are oppositely arranged, the fixed pole plate and the first bonding pad are connected through a metal lead, the induction pole plate and the second bonding pad are connected through a metal lead, and the fixed pole plate and the induction pole plate are vertically arranged. The pressure sensor innovatively adopts the vertically arranged fixed polar plate and induction polar plate structure, and breakthroughs the capacitor arranged at two sides of the second base body, so that environmental pollutants can not be attached to the surface of the vertical sensitive film, and the long-term use reliability of the pressure sensor is greatly improved. This pressure sensor has and can avoid the granule dust to pile up, and difficult inefficacy and the advantage that long-term use reliability is high to, through adopting the support column to suspend the second base member in the holding tank, still have the advantage that the temperature drift is little.
Description
Technical Field
The invention relates to the technical field of microelectronics, in particular to a pressure sensor and a manufacturing method of the pressure sensor.
Background
As a sensing measurement module widely used, the pressure sensor is also developed explosively in the fields of wearable, household appliances, new energy automobiles, smart environments and the like along with the development of the Internet of things. The mainstream capacitive pressure sensor mostly adopts the design principle of a flat capacitor, a sensitive capacitor is formed by an upper polar plate and a lower polar plate, wherein the upper polar plate and the lower polar plate are horizontally tiled and are arranged at a certain distance from top to bottom to form a capacitor, and when test pressure acts on the surface of the upper polar plate, the upper polar plate is deformed, and the trigger capacitor is linearly changed. Along with the increase of the service cycle, dust, particles and the like on the surface of the sensitive film are accumulated and increased, and particularly when the particles with larger diameters are polluted, the performance of the capacitance pressure sensor is greatly influenced and even damaged due to the fact that the sensitive film is thinner, and the long-term use reliability of the sensor is seriously reduced.
In addition, in order to ensure sufficient sensitivity for pressure measurement, the sensitive membrane of the plate is usually designed to be thin, and in order to ensure the sensitivity for measurement, a protective gel cannot be used on the surface of the sensitive membrane for membrane surface protection, and even if the protective gel is on the surface, particles can fall on the protective gel to affect the performance of the pressure sensor.
Therefore, there is a need for a new pressure sensor and a method for manufacturing the same, which solves or at least alleviates the above technical drawbacks.
Disclosure of Invention
The invention mainly aims to provide a pressure sensor and a manufacturing method of the pressure sensor, and aims to solve the technical problems that the pressure sensor is easy to damage and low in reliability in the prior art.
In order to achieve the above object, according to an aspect of the present invention, the present invention provides a pressure sensor, which includes an MEMS chip, where the MEMS chip includes a base, and a first pad and a second pad that are disposed on the base, a capacitor is disposed on the base, the capacitor includes a fixed plate and an induction plate that are disposed opposite to each other, the fixed plate and the first pad, and the induction plate and the second pad are all connected through a metal lead, and both the fixed plate and the induction plate are disposed vertically.
In an embodiment, the pressure sensor further includes an ASIC chip, the substrate includes a first substrate and a second substrate, the first substrate is bonded to the ASIC chip, the second substrate is provided with the capacitor, the first substrate is formed with an accommodating groove, and the second substrate is suspended in the accommodating groove and forms a gap with the first substrate.
In an embodiment, the pressure sensor further includes a supporting pillar, a bottom end of the supporting pillar is connected to a bottom surface of the accommodating groove, a top end of the supporting pillar is connected to the second base body, the capacitor is disposed on an outer side wall of the second base body, the sensing electrode plate is disposed on one side of the fixed electrode plate away from the second base body, and the sensing electrode plate and the side wall of the first base body are spaced.
In one embodiment, the top surface of the first substrate, the top surface of the second substrate and the top surface of the support post are flush.
In an embodiment, the number of the capacitors is two, and the two capacitors are respectively disposed on two opposite sides of the second substrate.
In one embodiment, a plurality of release holes vertically penetrating through the second substrate are formed on the second substrate.
In an embodiment, a sealing layer is further disposed on the second substrate, and the sealing layer is respectively connected to one side of the fixed polar plate and one side of the induction polar plate, so that a vacuum cavity is formed between the induction polar plate and the fixed polar plate.
In one embodiment, the sealing layer is a silicon oxide layer.
According to another aspect of the present invention, the present invention also provides a method for manufacturing a pressure sensor, the method for manufacturing the pressure sensor comprising:
providing a first substrate, etching to form an accommodating groove on the first substrate, and manufacturing a sacrificial layer, a support pillar and a second substrate in the accommodating groove;
etching the second substrate to form a release hole, an isolation cavity and a cavity;
growing a polar plate material in the cavity and the isolation cavity to form a polar plate material layer;
etching the polar plate material layer to form a fixed polar plate and an induction polar plate which are vertical and are oppositely arranged at intervals;
manufacturing a first bonding pad, a second bonding pad and a metal lead, and connecting the first bonding pad with a fixed polar plate, the second bonding pad with the induction polar plate through the metal lead; a sealing layer is manufactured to connect the upward sides of the fixed polar plate and the induction polar plate;
and injecting etching liquid into the sacrificial layer through the release hole to remove the sacrificial layer, so that the bottom surface of the accommodating groove and the bottom surface of the second substrate are arranged at intervals.
In one embodiment, the step of etching the release hole, the isolation cavity and the cavity on the second substrate comprises:
and etching the two opposite sides of the second substrate respectively to form the isolation cavity and the cavity, wherein the isolation cavity separates the side wall of the second substrate from the side wall of the first substrate.
In one embodiment, the step of growing the plate material in the cavity and the isolation cavity to form the plate material layer comprises:
and depositing doped polysilicon in the cavity and the isolation cavity by a deposition mode to form the plate material layer.
In an embodiment, the step of etching the plate material layer to form a fixed plate and an induction plate includes:
and etching the substrate material layer in the cavity to form the fixed polar plate, etching the polar plate material layer in the isolation cavity to form the induction polar plate, and forming a gap between the induction polar plate and the side wall of the first base body.
In one embodiment, the step of fabricating the first pad, the second pad and the metal lead includes:
and manufacturing a first bonding pad and a second bonding pad on the top surface of the first substrate, and manufacturing metal leads on the first substrate, the second substrate and the support columns.
In the above scheme, pressure sensor includes the MEMS chip, and the MEMS chip includes the base member and sets up first pad and the second pad on the base member, is provided with electric capacity on the base member, and electric capacity is including relative fixed polar plate and the response polar plate that sets up, and fixed polar plate and first pad, response polar plate and second pad all are through metal pin connection, the equal vertical setting of fixed polar plate and response polar plate. The fixed polar plate is fixedly connected to the base body, the fixed polar plate and the induction polar plate form a capacitor, and test pressure acts on the surface of the induction polar plate to cause the induction polar plate to deform and trigger the linear change of the capacitance. The sensing polar plate comprises a sensing film or is made of the sensing film, the invention innovatively adopts a vertically arranged sensing polar plate structure to ensure that the sensing film is vertically arranged, and replaces the placement structure of the horizontally arranged sensing film in the prior art, and in the use process, because the sensing film is of a vertical structure, environmental pollutants cannot be attached to the surface of the vertical sensing film, so that the problem that particles and dust are accumulated on the sensing film is avoided; the problem of the traditional capacitance pressure sensor along with the increase of particulate matter in long-term use performance decline gradually, even inefficacy is solved, very big improvement capacitance pressure sensor's long-term reliability of using. The invention has the advantages of avoiding accumulation of particle dust, being difficult to lose efficacy and having high reliability in long-term use.
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 some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.
FIG. 1 is a schematic cross-sectional view of a MEMS chip of a pressure sensor according to an embodiment of the present invention;
FIG. 2 is a top view of a MEMS chip of a pressure sensor of an embodiment of the present invention;
FIG. 3 is a schematic cross-sectional view of a pressure sensor according to an embodiment of the present invention;
fig. 4 to 9 are schematic structural changes of a method for manufacturing a pressure sensor according to an embodiment of the present invention; wherein,
FIG. 4 is a schematic structural diagram of a first substrate, a second substrate, a supporting pillar, and a sacrificial layer of a method for manufacturing a pressure sensor according to an embodiment of the invention;
FIG. 5 is a schematic view of the structure of FIG. 4 with the compartments, cavities and release holes provided;
FIG. 6 is a schematic diagram of a layer of plate material disposed over the structure of FIG. 5;
FIG. 7 is a schematic diagram of a structure of etching a fixed plate and an inductive plate on the structure of FIG. 6;
FIG. 8 is a schematic diagram of a structure in which metal leads, a sealing layer, a first pad and a second pad are disposed on the structure of FIG. 7;
FIG. 9 is a schematic view, similar to FIG. 1, of a structure for removing a sacrificial layer over the structure of FIG. 8;
FIG. 10 is a schematic flow chart illustrating a method of fabricating a pressure sensor according to a first embodiment of the present invention;
FIG. 11 is a schematic flow chart illustrating a method for manufacturing a pressure sensor according to a second embodiment of the present invention;
FIG. 12 is a schematic flow chart illustrating a method for manufacturing a pressure sensor according to a third embodiment of the present invention;
fig. 13 is a schematic flowchart of a method for manufacturing a pressure sensor according to a fourth embodiment of the present invention.
Description of the reference symbols:
100. an MEMS chip; 200. an ASIC chip; 1. a first substrate; 2. a second substrate; 3. a capacitor; 31. fixing the polar plate; 32. an induction pole plate; 4. a first bonding pad; 5. a second pad; 6. a metal lead; 7. a gap; 8. a support pillar; 9. accommodating a tank; 91. an inner sidewall; 10. a release aperture; 11. a sealing layer; 12. a partition plate; 13. a pole plate material layer; 14. a separation chamber; 15. a cavity; 16. a sacrificial layer.
The implementation, functional features and advantages of the present invention will be further explained with reference to the accompanying drawings.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent 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 obtained by a person skilled in the art without inventive efforts based on the embodiments of the present invention, are within the scope of protection of the present invention.
It should be noted that all the directional indicators (such as upper and lower 8230; etc.) in the embodiments of the present invention are only used for explaining the relative positional relationship between the components, the motion situation, etc. in a specific posture (as shown in the drawings), and if the specific posture is changed, the directional indicator is changed accordingly.
In addition, the descriptions related to "first", "second", etc. in the present invention are only for descriptive purposes and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the feature.
Moreover, the technical solutions in the embodiments of the present invention may be combined with each other, but it is necessary to be able to be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, the combination of the technical solutions should be considered to be absent, and is not within the protection scope of the present invention.
Referring to fig. 1 and 2, according to an aspect of the present invention, the present invention provides a pressure sensor, including a MEMS chip 100, where the MEMS chip 100 includes a substrate, and a first bonding pad 4 and a second bonding pad 5 disposed on the substrate, a capacitor 3 is disposed on the substrate, the capacitor 3 includes a fixed plate 31 and an induction plate 32 disposed opposite to each other, the fixed plate 31 and the first bonding pad 4, and the induction plate 32 and the second bonding pad 5 are connected by a metal lead 6, and the fixed plate 31 and the induction plate 32 are both disposed vertically.
In the above embodiment, the fixed plate 31 is fixedly connected to the substrate, the fixed plate 31 and the sensing plate 32 form the capacitor 3, and the test pressure acts on the surface of the sensing plate 32 to cause the sensing plate 32 to deform, thereby triggering the linear change of the capacitor 3. The sensing pole plate 32 comprises a sensing film or the sensing pole plate 32 is made of a sensing film and is a movable pole plate, the embodiment innovatively adopts a structure of the sensing pole plate 32 which is vertically arranged, so that the sensing film is vertically arranged, and the structure of the sensing film which is horizontally arranged in the prior art is replaced, and in the using process, because the sensing film is of a vertical structure, environmental pollutants cannot be attached to the surface of the vertical sensing film, so that the problem that particles and dust are accumulated on the sensing film is avoided; the problem of the traditional pressure sensor along with the increase of particulate matter in the long-term use performance decline gradually, even the condition of inefficacy is solved, very big improvement pressure sensor's long-term reliability of using. This embodiment has can avoid granule dust to pile up, is difficult for becoming invalid and long-term use advantage that the reliability is high.
Referring to fig. 3, in an embodiment, the pressure sensor further includes an ASIC chip 200, the substrate includes a first substrate 1 and a second substrate 2, the first substrate 1 is bonded to the ASIC chip 200, a capacitor 3 is disposed on the second substrate 2, the first substrate 1 is formed with a receiving groove 9, and the second substrate 2 is suspended in the receiving groove 9 and forms a gap 7 with the first substrate 1. Specifically, the first substrate 1 and the ASIC chip 20 may be bonded by glue, and the glue may be silicon gel. The pressure sensor can include MEMS chip 100 and ASIC chip 200 of range upon range of setting from top to bottom to, along with the development of science and technology, put forward miniaturized, intelligent, the requirement that integrates to the intelligent sensor, for improving the whole space utilization of product, generally can stack pressure sensor MEMS chip 100 on ASIC chip 200 and carry out integrated package. Because the ASIC can give off heat in the course of working, make MEMS pressure sensor not only receive ambient temperature's influence, more receive ASIC heating influence, the heat is and inside transmitting the chip from MEMS chip 100 bottom, leads to the emergence of temperature drift, very big reduction MEMS chip 100's each item performance, the temperature drift characteristic is obvious. This embodiment is through setting up the base member into first base member 1 and second base member 2, is formed with holding tank 9 on the first base member 1, second base member 2 suspension in holding tank 9 and with first base member 1 between have clearance 7, clearance 7 is first base member 1 and the setting of second base member 2 interval promptly, plays the effect of separation heat transfer. The ASIC chip 200 is connected to the first substrate 1, and in particular, may be connected to the bottom surface of the first substrate 1. Therefore, due to the existence of the gap, the bottom surfaces of the first substrate and the second substrate are spaced, and the heat emitted by the ASIC chip 200 is blocked and cannot be transferred to the second substrate 2 after being transferred to the first substrate 1, and is less likely to be transferred to the capacitor 3 disposed on the second substrate 2, which does not affect the MEMS chip 100. In particular, the pressure capacitor 3 is generally vacuum-sealed, and the gap 7 can play a better role in heat insulation. This embodiment provides a side sensitive capacitive MEMS pressure sensor structure with high reliability and low temperature drift.
Referring to fig. 1 and 2, in an embodiment, the pressure sensor further includes a supporting pillar 8, a bottom end of the supporting pillar 8 is connected to a bottom surface of the accommodating groove 9, a top end of the supporting pillar 8 is connected to the second base body 2, the capacitor 3 is disposed on an outer sidewall of the second base body 2, the sensing plate 32 is disposed on one side of the fixed plate 31 away from the second base body 2, and the sensing plate 32 and a sidewall of the first base body 1 are disposed at an interval, that is, a gap 7 exists between the sensing plate 32 and an inner sidewall 91 of the accommodating groove 9. In particular, second substrate 2 may be suspended in receiving groove 9 by providing support posts 8 such that second substrate 2, fixed plate 31 of capacitor 3 and sensing plate 32 are all spatially isolated from the bottom of first substrate 1. It should be noted that, referring to fig. 2, the support bar has two opposite side surfaces connected to the side walls of the first substrate 1, but the two side surfaces are not the side surfaces of the second substrate 2 where the capacitor 3 is disposed, so as to facilitate the routing of the metal lead 6. In the use process, the heat emitted by the ASIC at the bottom is difficult to transfer to the sensitive structural unit of the capacitor 3, so that a physical heat isolation system structure is formed, the temperature drift characteristic of the pressure sensor is reduced, and the overall test performance of the pressure sensor is improved. This embodiment is significantly superior to conventional horizontally placed sensitive membrane pressure sensor configurations. Specifically, the supporting pillars 8, the first base 1, and the second base 2 may be made of single crystal silicon. Moreover, the substrate of the capacitor 3 is connected with the first pad 4 and the second pad 5 through the metal lead 6, so that the top surface of the first base body 1, the top surface of the second base body 2 and the top surface of the support post 8 are arranged in a flush manner, and the metal lead 6 is conveniently arranged.
Referring to fig. 1 and 2, in an embodiment, the number of the capacitors 3 is two, and the two capacitors 3 are respectively disposed on two opposite sides of the second substrate 2. Certainly, the number of the first bonding pads 4 and the second bonding pads 5 is also two, each of the first bonding pads 4 and the second bonding pads 5 is arranged corresponding to one capacitor 3 and is used for being connected with two electrode plates of the capacitor 3 respectively, the double-capacitor 3 structure is adopted in the embodiment, various indexes such as the sensitivity and the linearity of the pressure sensor can be greatly improved, and therefore the overall testing precision of the pressure sensor is greatly improved. Of course, those skilled in the art will readily understand that a plurality of capacitors 3 may be provided according to actual needs.
Referring to fig. 1 and 2, in an embodiment, a plurality of release holes 10 vertically penetrating through the second substrate 2 are formed on the second substrate 2. The release hole 10 is mainly used for injecting etching liquid to remove the sacrificial layer 16 generated in the middle process in the manufacturing process of the pressure sensor, which will be discussed in detail later in the manufacturing method of the pressure sensor.
Referring to fig. 1, in an embodiment, a sealing layer 11 is further disposed on the second substrate 2, and the sealing layer 11 is respectively connected to one side of the fixed plate 31 and one side of the sensing plate 32, so that a vacuum cavity is formed between the sensing plate 32 and the fixed plate 31. The sealing layer 11 is a silicon oxide layer. The bottom ends of the fixed polar plate 31 and the induction polar plate 32 are hermetically connected by the first base body 1, the top ends form a vacuum cavity by arranging the sealing layer 11 between the induction polar plate 32 and the fixed polar plate 31, the vacuum cavity is used as a reference cavity during pressure measurement, the sealing layer 11 can be made of silicon oxide, and the induction polar plate 32 and the fixed polar plate 31 are processed into a shape similar to a hat after silicon oxide is generated by deposition.
Referring to fig. 10, according to the first embodiment of the present invention, the present invention also provides a method of manufacturing a pressure sensor, the method of manufacturing a sensor including:
s10, providing a first substrate 1, etching the first substrate 1 to form an accommodating groove 9, and manufacturing a sacrificial layer 16, a support pillar 8 and a second substrate 2 in the accommodating groove 9;
referring to fig. 4, the first substrate 1 may be a single crystal silicon, the first substrate 1 is etched on the first substrate 1 by plasma etching to form an accommodating groove 9, then a sacrificial layer 16 is deposited on the bottom surface of the accommodating groove 9, the sacrificial layer 16 may be made of silicon oxide, and then the supporting posts 8 and the second substrate 2 are fabricated, the bottom surface of the second substrate 2 is separated from the bottom surface of the accommodating groove 9 by the sacrificial layer 16, so that the first substrate 1 is spaced from the bottom surface of the second substrate 2 after the sacrificial layer 16 is removed to form a physical isolation structure. Meanwhile, the bottom ends of the supporting columns 8 penetrate through the sacrificial layer 16 to be connected with the bottom surfaces of the accommodating grooves 9, the top surfaces of the supporting columns 8 and the top surfaces of the first base body 1 and the second base body 2 are arranged in a flush mode, the first base body 1 and the supporting columns 8 can be made of monocrystalline silicon, and the side surfaces of the grown first base body 1 are attached to the inner side walls 91 of the accommodating grooves 9;
s20, etching the second substrate 2 to form a release hole 10, an isolation cavity 14 and a cavity 15;
referring to fig. 5, specifically, a release hole 10, an isolation cavity 14 and a cavity 15 may be etched and formed by plasma etching, where the release hole 10 is used for injecting an etching liquid to remove a sacrificial layer 16, and the release hole 10 vertically penetrates through the second substrate 2 and is connected to the sacrificial layer 16; the separation cavity 14 forms a gap between the outer side wall of the second base body 2 and the inner side wall 91 of the accommodating groove 9, and the cavity 15 and the separation cavity 14 are separated by a partition plate 12 of the second polar plate;
s30, growing a plate material in the cavity 15 and the isolation cavity 14 to form a plate material layer 13;
referring to fig. 6, a substrate material layer may be grown in the cavities 15 and the isolated cavities 14 by deposition to fill the cavities 15 and the isolated cavities 14;
s40, etching the pole plate material layer 13 to form a fixed pole plate 31 and an induction pole plate 32 which are vertically arranged at intervals;
referring to fig. 7, a plasma etching method may also be used here to vertically dig a groove in the plate material layer 13, leaving a fixed plate 31 fixed on the plate and an induction plate 32 attached to the isolation plate, where the induction plate may be a sensitive film used for inducing an external pressure signal and is a movable plate, the fixed plate 31 and the induction plate 32 form two substrates of the capacitor 3, a gap 7 is formed between the induction plate 32 and an inner side wall 91 of the accommodation groove 9 to form a spatial isolation, and the induction plate 32 and the fixed plate 31 are respectively disposed on two opposite sides of the isolation plate;
s50, manufacturing a first bonding pad 4, a second bonding pad 5 and a metal lead 6, and connecting the first bonding pad 4 with the fixed pole plate 31, the second bonding pad 5 with the induction pole plate 32 through the metal lead 6; and the sealing layer 11 is made to connect the upward sides of the fixed polar plate 31 and the induction polar plate 32;
referring to fig. 8, the electric signal generated after the external pressure is sensed by the capacitor 3 may be transferred out through the first pad 4, the second pad 5 and the metal lead 6, such as to the ASIC chip 200, and the first pad 4 and the second pad 5 and the metal lead 6 may be made of copper or gold.
S60, injecting an etching solution into the sacrificial layer 16 through the release holes 10 to remove the sacrificial layer 16, so that the bottom surface of the accommodating groove 9 is spaced apart from the bottom surface of the second substrate 2.
Referring to fig. 9, the etching solution may be hydrofluoric acid, and the sacrificial layer 16 made of silicon oxide may be dissolved by the hydrofluoric acid, so that the bottom surface of the receiving groove 9 and the bottom surface of the second substrate 2 are spaced apart from each other to achieve physical isolation, and heat generated by the ASIC chip 200 cannot be transferred from the bottom surface of the receiving groove 9 to the first substrate and the capacitor, thereby blocking a path of heat conduction.
In the above embodiment of the present invention, the fixed plate 31 is fixedly connected to the substrate, the fixed plate 31 and the sensing plate 32 form the capacitor 3, and the test pressure acts on the surface of the sensing plate 32, so that the sensing plate 32 deforms, and the linear change of the capacitor 3 is triggered. The sensing polar plate 32 comprises a sensing film or the sensing polar plate 32 is made of a sensing film, the embodiment innovatively adopts a vertically-arranged sensing polar plate 32 structure, so that the sensing film is vertically arranged, and a placement structure of the horizontally-arranged sensing film in the prior art is replaced, and in the use process, because the sensing film is of a vertical structure, environmental pollutants cannot be attached to the surface of the vertical sensing film, so that the problem that particles and dust are accumulated on the sensing film is avoided; the problem of the traditional pressure sensor along with the increase of particulate matter in the long-term use performance decline gradually, even the condition of inefficacy is solved, very big improvement pressure sensor's long-term reliability of using. The pressure sensor manufactured by the embodiment has the advantages of capability of avoiding accumulation of particle dust, difficulty in failure and high reliability in long-term use.
Referring to fig. 11, in an embodiment, the step S20 includes:
s201, etching on two opposite sides of the second substrate 2 to form an isolation cavity 14 and a cavity 15, wherein the isolation cavity 14 separates the side wall of the second substrate 2 from the side wall of the first substrate 1.
The number of the capacitors 3 can be two, and at this time, the isolation cavity 14 and the cavity 15 need to be respectively arranged on two sides of the second substrate 2, and the two capacitors 3 are respectively arranged on two opposite sides of the second substrate 2. Of course, the number of the first bonding pads 4 and the second bonding pads 5 is two, and each of the first bonding pads 4 and the second bonding pads 5 corresponds to one capacitor 3.
In the embodiment of the invention, the isolation cavity 14 and the cavity 15 are respectively formed on the two opposite sides of the second substrate 2 by etching, and the isolation cavity 14 separates the side wall of the second substrate 2 from the side wall of the first substrate 1, so that the double-capacitor 3 structure can be manufactured, and various indexes such as sensitivity, linearity and the like of the pressure sensor can be greatly improved, thereby greatly improving the overall test precision of the pressure sensor. Of course, those skilled in the art will readily understand that a plurality of capacitors 3 may be provided according to actual needs.
Referring to fig. 12, in one embodiment, the step of S30 includes:
and S301, depositing doped polysilicon in the cavity 15 and the isolation cavity 14 by a deposition mode to form a plate material layer 13. The plate material fills the cavity 15 and the isolation cavity 14 to form the plate material layer 13, which is ready for subsequent partial removal by etching to form the vertically arranged fixed plate 31 and the inductive plate 32.
Referring to fig. 13, in one embodiment, the step of S40 includes:
s401, etching the substrate material layer in the cavity 15 to form a fixed polar plate 31, etching the polar plate material layer 13 in the isolation cavity 14 to form an induction polar plate 32, and forming a gap 7 between the induction polar plate 32 and the side wall of the first base body 1. Carry out the sculpture through the etching liquid to the polar plate material layer 13 in the cavity 15 and form fixed polar plate 31, fixed polar plate 31 and baffle separate the setting to carry out the sculpture through the etching liquid and form response polar plate 32 in the polar plate material layer 13 in keeping apart the cavity 14, response polar plate 32 is attached to and on the baffle, be formed with gapped 7 between response polar plate 32 and the inside wall 91 of holding tank 9, form the space and keep apart, and response polar plate 32 and fixed polar plate 31 respectively with the relative both sides of baffle.
In one embodiment, the step of S50 includes:
s501, manufacturing a first bonding pad 4 and a second bonding pad 5 on the top surface of the first substrate 1, and manufacturing a metal lead 6 on the first substrate 1, the second substrate 2 and the support pillar 8. At least two metal leads 6 are provided, one metal lead 6 is connected with the first bonding pad 4 and the fixed pole plate 31, and the other metal lead 6 is connected with the second bonding pad 5 and the induction pole plate 32.
The above description is only an alternative embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications and equivalents made by the claims and the accompanying drawings, or directly/indirectly applied to other related technical fields, are included in the scope of the present invention.
Claims (13)
1. The utility model provides a pressure sensor, its characterized in that, includes the MEMS chip, the MEMS chip include the base member with set up in first pad and second pad on the base member, be provided with electric capacity on the base member, electric capacity is including relative fixed polar plate and the response polar plate that sets up, fixed polar plate with first pad the response polar plate with the second pad all is through metal pin connection, fixed polar plate with the equal vertical setting of response polar plate.
2. The pressure sensor of claim 1, further comprising an ASIC chip, the substrate including a first substrate and a second substrate, the first substrate bonded to the ASIC chip, the second substrate having the capacitor disposed thereon, the first substrate formed with a receiving groove, the second substrate suspended in the receiving groove and formed with a gap from the first substrate.
3. The pressure sensor of claim 2, further comprising a supporting pillar, wherein a bottom end of the supporting pillar is connected to a bottom surface of the accommodating groove, a top end of the supporting pillar is connected to the second substrate, the capacitor is disposed on an outer sidewall of the second substrate, the sensing electrode plate is disposed on a side of the fixed electrode plate away from the second substrate, and the sensing electrode plate is spaced apart from a sidewall of the first substrate.
4. The pressure sensor of claim 3, wherein the top surface of the first substrate, the top surface of the second substrate, and the top surface of the support post are disposed flush.
5. A pressure sensor according to any one of claims 2 to 4, wherein the number of the capacitors is two, and two capacitors are respectively disposed on opposite sides of the second substrate.
6. The pressure sensor according to any one of claims 2 to 4, wherein a plurality of release holes are formed vertically through the second substrate.
7. A pressure sensor according to any one of claims 2 to 4, wherein a sealing layer is provided on the second substrate, the sealing layer being connected to one side of the fixed plate and one side of the sensing plate respectively, so that a vacuum cavity is formed between the sensing plate and the fixed plate.
8. The pressure sensor of claim 7, wherein the sealing layer is a silicon oxide layer.
9. A method of making a pressure sensor, the method comprising:
providing a first substrate, etching the first substrate to form an accommodating groove, and manufacturing a sacrificial layer, a support pillar and a second substrate in the accommodating groove;
etching the second substrate to form a release hole, an isolation cavity and a cavity;
growing a polar plate material in the cavity and the isolation cavity to form a polar plate material layer;
etching the polar plate material layer to form a fixed polar plate and an induction polar plate which are vertical and are oppositely arranged at intervals;
manufacturing a first bonding pad, a second bonding pad and a metal lead, and connecting the first bonding pad, the fixed polar plate, the second bonding pad and the induction polar plate through the metal lead; a sealing layer is manufactured to connect the upward sides of the fixed polar plate and the induction polar plate;
and injecting etching liquid into the sacrificial layer through the release hole to remove the sacrificial layer, so that the bottom surface of the accommodating groove and the bottom surface of the second base body are arranged at intervals.
10. The method of claim 9, wherein the step of etching the release hole, the isolation cavity, and the cavity in the second substrate comprises:
and etching the two opposite sides of the second substrate respectively to form the isolation cavity and the cavity, wherein the isolation cavity separates the side wall of the second substrate from the side wall of the first substrate.
11. The method of claim 9, wherein the step of growing a plate material to form a plate material layer in the cavity and in the isolation cavity comprises:
and depositing doped polysilicon in the cavity and the isolation cavity by a deposition mode to form the plate material layer.
12. The method of claim 9, wherein the step of etching the plate material layer to form a fixed plate and a sensing plate comprises:
and etching the substrate material layer in the cavity to form the fixed polar plate, etching the polar plate material layer in the isolation cavity to form the induction polar plate, and forming a gap between the induction polar plate and the side wall of the first base body.
13. The method of fabricating a pressure sensor of claim 9, wherein the step of fabricating the first bonding pad, the second bonding pad, and the metal lead comprises:
and manufacturing a first bonding pad and a second bonding pad on the top surface of the first substrate, and manufacturing metal leads on the first substrate, the second substrate and the support columns.
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