CN105060238B - The production method of capacitance pressure transducer, based on ultrathin membrane - Google Patents

Abstract

The present invention relates to pressure sensors, a kind of production method of the capacitance pressure transducer, based on ultrathin membrane is provided, in at least one layer of ultrathin membrane of preparation on substrate, it is further prepared with one layer of insulation film simultaneously, at least one cavity is etched on insulation film, the both ends of the surface of insulation film is fitted in respectively using ultrathin membrane and substrate, forms the sealing to cavity, then substrate is removed, is exported the charge on ultrathin membrane and substrate by two pads.In the present invention, the sensitive thin film of pressure sensor uses ultrathin membrane, in the case where disclosure satisfy that very small dimensions, also there is higher susceptibility, support to insulation film and ultrathin membrane is also formed additionally as the substrate of lower electrode, simultaneously between insulation film and ultrathin membrane then using be bonded or direct growth preparation by the way of be attached, structural stability is very high.

Description

Fabrication method of capacitive pressure sensor based on ultra-thin film

technical field

The invention relates to a pressure sensor, in particular to a method for manufacturing a capacitive pressure sensor based on an ultra-thin film.

Background technique

Pressure sensors are widely used, such as industrial electronics: industrial ingredient weighing, digital flow meters, and digital pressure gauges; consumer electronics: liquid level control pressure sensors for solar water heaters, dishwashers, water dispensers, washing machines, and air conditioners. Sensors, microwave ovens, health scales and sphygmomanometers, etc.; automotive electronics: common rail pressure sensors for diesel engines, intake manifold pressure sensors for automotive engines, air pressure sensors for automotive brake systems, and engine oil pressure sensors.

The development trend of pressure sensors is smaller size, from micrometer scale to nanometer scale, higher sensitivity, higher reliability, and wider application range. Most of the existing MEMS pressure sensors are made of cavities on the silicon substrate through body processing or surface processing technology, and a sensitive thin film is made on the top of the cavity with a thickness of several microns to tens of microns. In order to obtain a sensor with high sensitivity while reducing its size, thinner sensitive films must be used. However, due to the limitation of the physical properties of silicon, it is very difficult to manufacture ultra-thin silicon film pressure sensors with higher sensitivity and smaller size.

Contents of the invention

The purpose of the present invention is to provide a method for manufacturing a capacitive pressure sensor based on an ultra-thin film, aiming at solving the problem that the silicon film of the existing capacitive pressure sensor is difficult to be compatible with small size and high sensitivity.

The present invention is achieved like this:

The invention provides a method for manufacturing a capacitive pressure sensor based on an ultra-thin film, comprising the following steps:

At least one layer of ultra-thin films sequentially laminated are prepared on a substrate;

preparing a layer of insulating film, at least one cavity is etched on the insulating film, and the cavity runs through the insulating film;

One of the ultra-thin films located on the outside is prepared as a whole with the insulating film, the ultra-thin film seals each of the cavities, and a substrate is provided on the side of the insulating film away from the ultra-thin film;

The substrate is removed, and two pads are installed, and the two pads are respectively electrically connected to the other ultra-thin film on the outside and the substrate.

Specifically, the ultra-thin film is a semiconductor compound film, and the semiconductor compound is one of gallium nitride, aluminum gallium nitride, indium nitride, indium gallium nitride, gallium arsenide, indium phosphide, zinc oxide and zinc antimonide kind.

Further, when the semiconductor compound thin film is produced, it is doped, and the forming material of the substrate is semiconductor or ceramics.

Specifically, an insulating film is prepared on the base, and after each cavity is etched, the insulating film is bonded to the outer semiconductor compound film.

Further, the ultra-thin film is a graphene film.

Further, when making the graphene film, a copper film or a nickel film is prepared on the substrate first, and at least one layer of the graphene film is grown on the copper film or the nickel film.

Further, the insulating film is prepared on the outer graphene film, and after etching each of the cavities, the substrate is bonded to the insulating film, and the substrate seals each of the cavities.

Further, a metal layer is formed on the upper surface of the substrate, the metal layer is electrically connected to one of the pads, and the thickness of the metal layer is smaller than the thickness of the insulating film.

Further, the material of the insulating film is one of silicon nitride, silicon dioxide, aluminum oxide, aluminum nitride, polymethyl methacrylate and polyimide.

Specifically, the thickness of the ultra-thin film ranges from nanometer to micrometer.

The present invention has the following beneficial effects:

In the manufacturing method of the present invention, at least one layer of ultra-thin film is first prepared on a substrate, that is, one or more layers of ultra-thin film, and a layer of insulating film is also prepared at the same time, and at least one cavity is opened on the insulating film, and the insulating film and One of the ultra-thin films is prepared as a whole, one end of the insulating film is located on a substrate, and the other end is bonded to the ultra-thin film, and then the substrate is removed, and two welding pads are used to electrically connect the substrate and the ultra-thin film respectively. In the above manufacturing method, one side of the insulating film is sealed with an ultra-thin film, and the other side is the substrate. Compared with the traditional silicon film, the ultra-thin film can also have higher sensitivity while ensuring a smaller size, while the substrate It is used as the supporting structure of the insulating film and the ultra-thin film, and also serves as the lower electrode. Both the insulating film and the ultra-thin film can be prepared by chemical vapor deposition. For the ultra-thin film, it is first grown on the substrate, and then it is transferred to the insulating film, and the insulating film and the ultra-thin film are bonded. It can be connected by fusion or direct growth preparation, and the structural stability is very high.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. Those skilled in the art can also obtain other drawings based on these drawings without creative work.

Fig. 1 is the top view of the capacitive pressure sensor based on ultra-thin film that the embodiment of the present invention provides;

Figure 2 is a schematic structural diagram of the A-A direction of Figure 1 and the pad is derived from the top;

Figure 3 is a schematic structural diagram of the A-A direction of Figure 1 and the pad is derived from the bottom;

Fig. 4 is the structural schematic diagram that prepares insulating film on the substrate in embodiment one;

5 is a schematic structural view of an insulating film etching cavity in Embodiment 1;

Fig. 6 is the schematic structural representation of the semiconductor compound thin film prepared on the substrate in embodiment one;

FIG. 7 is a schematic structural view of the bonding of an insulating film and a semiconductor compound film in Embodiment 1;

FIG. 8 is a schematic structural view of removing the substrate in Embodiment 1;

FIG. 9 is a schematic structural diagram of installing two pads in Embodiment 1;

Fig. 10 is the structural representation of preparing copper film on the substrate in embodiment two;

Fig. 11 is the structural representation that prepares graphene thin film on copper film in embodiment two;

Fig. 12 is the structural representation of insulating film prepared on the graphene film in embodiment two;

13 is a schematic structural view of the insulating film etching cavity in the second embodiment;

14 is a schematic structural view of a bonding substrate on an insulating film in Embodiment 2;

Fig. 15 is a schematic structural diagram of removing the substrate in Embodiment 2;

FIG. 16 is a schematic structural diagram of installing two pads in the second embodiment.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Referring to Fig. 1-Fig. 3, the embodiment of the present invention provides a kind of manufacturing method of capacitive pressure sensor based on ultra-thin film, mainly applies ultra-thin film 1 in pressure sensor, and ultra-thin film 1 is as sensitive film, can sense pressure change, its It mainly includes the following production steps:

At least one layer of ultra-thin film 1 is prepared on a substrate 2, that is, the ultra-thin film 1 can be one layer or multi-layer, and when it is multi-layer, each layer of ultra-thin film 1 is stacked on the substrate 2 in turn. Together, the ultra-thin film 1 can be grown and formed on the substrate 2 by chemical deposition, and other different preparation methods can also be used according to the material of the ultra-thin film 1, and the substrate 2 can also be prepared according to the method of preparing the ultra-thin film 1 thereon. The material is different, and different materials are selected. The thickness of the ultra-thin film 1 ranges from nanometer to micrometer;

A layer of insulating film 3 is prepared, and at least one cavity 31 is etched on the insulating film 3 at the same time, the cavity 31 runs through the insulating film 3, and the insulating film 3 can be made of silicon nitride (Si ₃ N ₄ ), silicon dioxide (SiO ₂ ), aluminum oxide (Al ₂ O ₃ ), aluminum nitride (AlN), polymethyl methacrylate (PMMA) and polyimide (PI), etc., the thickness of each cavity 31 is the same as that of the insulating film 3 The thicknesses are all the same, and there can be one or more cavities 31. If there are cavities 31 of p _× q (p, q≥1) array, it is possible to make a quantity of p _× q capacitive pressure sensors, and the sensitivity is also P _× q times of a single pressure sensor, and in order to obtain higher sensitivity, the thickness of the insulating film 3 is very small, usually between micron and nanometer;

One of the ultra-thin film 1 and the insulating film 3 positioned on the outside are prepared as a whole, the ultra-thin film 1 seals each of the cavities 31, and the other side of the insulating film 3 (the side away from the ultra-thin film 1) is provided with a substrate 4 , the substrate 4 and the ultra-thin film 1 are respectively located on the two end faces of the insulating film 3, respectively sealing the cavities 31, the substrate 4 is made of semiconductor material or ceramic material, when it is a semiconductor substrate 4, it needs to be doped, and the doped The impurity material is silicon, silicon carbide, germanium, etc., and when it is a ceramic substrate 4, it can be made of materials such as aluminum oxide or silicon nitride;

Remove the substrate 2 on the ultra-thin film 1, and install two pads 5 at the same time, and the two pads 5 are electrically connected to another ultra-thin film 1 and the base 4 on the outside respectively, and the ultra-thin film 1 is used as the upper electrode, and the base 4 As the lower electrodes, the two pads 5 lead out the charges at the two electrodes respectively.

In the above manufacturing process, the insulating film 3 can be prepared by chemical deposition, physical deposition or spin coating, and the ultra-thin film 1 can also be prepared in different ways according to different materials, for example, when the ultra-thin film 1 is a semiconductor compound , which can be prepared by chemical deposition or physical deposition, which can be refined into metal organic chemical vapor deposition (MOCVD), atomic layer deposition (ALD), molecular beam epitaxy (MBE) or magnetron sputtering. In this embodiment, the ultra-thin film 1 is used on one side of the insulating film 3, which can also have higher sensitivity while meeting the small size requirements, and the substrate 4 can also form a The support for the insulating film 3 and the ultra-thin film 1 can be prepared by bonding between the insulating film 3 and the ultra-thin film 1 or directly growing the insulating film 3 on the ultra-thin film 1, and the structural stability is relatively high. Of course, since the base 4 is used as the lower electrode of the pressure sensor, a metal layer is formed on the upper surface of the base 4 , the metal layer is electrically connected to one of the pads 5 , and the thickness of the metal layer is smaller than that of the insulating film 3 .

Referring to Fig. 9, the above-mentioned preparation process is refined. When the ultra-thin film 1 is a semiconductor compound thin film 1a, it has a wide variety of properties and is widely used in fields such as optoelectronic devices, ultra-high-speed microelectronic devices, microwave devices and circuits. Different semiconductor compounds can be selected according to the needs during production. The general semiconductor compounds can be gallium nitride, aluminum gallium nitride, indium nitride, indium gallium nitride, gallium arsenide, indium phosphide, zinc oxide and zinc antimonide. One, and doping treatment is carried out during the fabrication process, so as to meet the conductivity performance of the semiconductor compound thin film 1a.

Referring to FIG. 16 , in another embodiment, the ultra-thin film 1 can also be a graphene film 1b. Graphene has very special properties: (1) The thickness of single-layer graphene is 0.335nm, and the graphene film 1b is on the order of nanometers; (2) Graphene has ultra-high Young's modulus (about 1000GPa) and fracture strength , the structure is very stable, and the conductivity is very strong (the mobility of carriers is extremely high, which can reach 15000cm ² V ^-1 S ^-1 and 60000cm ² V ^-1 S ^-1 at room temperature and liquid nitrogen temperature respectively); (3) The graphene film 1b can be stably adhered to the surface of silicon dioxide and is impenetrable; (4) The resistivity of graphene is extremely low (the resistivity is only about 10 ^-8 Ω·m, which is lower than that of common metals). In view of the above performance, the pressure sensor uses graphene as the ultra-thin film 1, which can meet the extremely small size and have high sensitivity. Graphene thin film 1b can be prepared by methods such as mechanical exfoliation method, liquid phase or gas phase direct exfoliation method, graphite oxide reduction method or chemical vapor deposition method, usually a layer of copper film 21 or nickel film is prepared on the substrate 2, and then The graphene thin film 1b is prepared on the copper film 21 or the nickel film by the above-mentioned method.

Referring to Fig. 2, Fig. 9 and Fig. 16, further, during manufacture, there can be two preparation methods for the insulating film 3, one of which is that when the ultra-thin film 1 is a semiconductor compound film 1a, the insulating film 3 is prepared on a substrate 4, the insulating film 3 is bonded with the ultra-thin film 1, and the other is that when the ultra-thin film 1 is a graphene film 1b, the insulating film 3 is directly prepared on the ultra-thin film 1, and the substrate 4 is bonded with the insulating film 3, which can be See the following two examples:

Referring to Fig. 1 and Fig. 4-Fig. 9, embodiment one, the ultra-thin film 1 is a semiconductor compound thin film 1a, a layer of insulating film 3 is prepared on the substrate 4, the thickness is in the nanometer to micron level, and a cavity is etched on the insulating layer film 31, the depth of the cavity 31 is the same as the thickness of the insulating layer; prepare a layer of ultra-thin film 1 on another substrate 2, the substrate 2 can be silicon, silicon carbide, germanium, sapphire, etc., and the ultra-thin film 1 is a semiconductor compound Thin film 1a, the thickness of the prepared film can range from nanoscale (such as single atomic layer film) to micron scale (such as GaN film of tens of microns prepared by MOCVD); the above two fabrication structures are bonded together, that is, semiconductor compound The film 1a is in contact with the insulating film 3 and bonded, and the substrate 2 and the substrate 4 are respectively located on both sides of the bonded structure; after bonding, the substrate 2 is removed, and the removal process includes laser lift-off, etching, etc., especially mentioned Because the thickness of the semiconductor compound film 1a is very small and is a brittle material, it is necessary to pay attention to the integrity and residual stress of the semiconductor compound film 1a when removing the substrate 2. If the substrate 2 is sapphire, laser lift-off is generally used, otherwise the semiconductor compound film 1a is easily damaged. If the thickness of the semiconductor compound film 1a is very small, only at the nanometer level, materials such as Si, SiC, and Ge can be used as the substrate 2, and the substrate 2 can be removed by etching to minimize the residual stress , to protect the semiconductor compound film 1a; through the above operations, the semiconductor compound film 1a, the insulating film 3, the substrate 4, and the cavity 31 are complete, and then the metal pad 5 is produced by using a commonly used IC or MEMS device to make electrodes. The signal from the upper and lower electrodes of the capacitor.

Referring to Fig. 1 and Fig. 10-Fig. 16, embodiment two, ultra-thin film 1 is graphene film 1b, prepares a layer of copper film 21 (also can be nickel film) on substrate 2, grows graphene on copper film 21 Thin film 1b, thickness can be one layer to multilayer, then prepare one layer insulating film 3 on graphene film 1b, it etches insulating film 3 out cavity 31, and the depth of cavity 31 is identical with the thickness of insulating film 3; Get a base 4, bond the base 4 and the insulating film 3 away from the side of the graphene film 1b, the substrate 2 and the base 4 are respectively located on both sides of the insulating film 3 and the graphene film 1b; after bonding, use The etching process removes the substrate 2. At this time, the graphene film 1b, the insulating film 3, the substrate 4, and the cavity 31 are complete. Next, the metal pad 5 is fabricated by using a commonly used IC or MEMS device to make electrodes to derive capacitance. Signals from the upper and lower electrodes.

Referring to Fig. 2 and Fig. 3, further, the charge derivation of the upper electrode ultra-thin film 1 and the lower electrode substrate 4 can be realized in various ways, one of which is that the pad 5 is directly fabricated on the conductive ultra-thin film 1, and the pad 5 Through the insulating film 3 and contact with the substrate 4 to achieve electrical connection, it should be noted that the insulating film 3 needs to be isolated from the ultra-thin film 1 to prevent the upper and lower electrodes from being directly connected when the pad 5 is made. This method is mainly suitable for wire bonding or Flip chip and other packaging forms. In another embodiment, it is similar to the above embodiment, except that the electrical signal is derived in a different way. The electrical signal is derived to the lower surface of the substrate 4 in the form of through-hole packaging on the substrate 4. When packaging, it is directly connected to the Alignment and reflow soldering of the substrate does not require wire bonding or flip-chip soldering. In this structural form, metal bumps 51 are formed at the ends of the two pads 5 .

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of the present invention. within the scope of protection.

Claims (8)

1. A method for making a capacitive pressure sensor based on an ultra-thin film, is characterized in that, comprises the following steps: At least one layer of ultra-thin films stacked sequentially are prepared on a substrate, the ultra-thin films are prepared by chemical deposition or physical deposition or peeling method, and the ultra-thin films are semiconductor compound thin films or graphene thin films; preparing a layer of insulating film, the insulating film is etched with a plurality of cavities, the cavities run through the insulating film, and each of the cavities is arranged in an array; One of the ultra-thin films located on the outside is prepared as a whole with the insulating film, and the ultra-thin film seals each of the cavities, and a substrate is arranged on the side of the insulating film away from the ultra-thin film, and on the A metal layer is formed on the upper surface of the substrate, the metal layer is electrically connected to one of the pads, and the thickness of the metal layer is smaller than the thickness of the insulating film; The substrate is removed, and two pads are installed, and the two pads are respectively electrically connected to the other ultra-thin film on the outside and the substrate. 2. The manufacturing method of the capacitive pressure sensor based on the ultra-thin film as claimed in claim 1, wherein: when the ultra-thin film is a semiconductor compound film, the semiconductor compound is gallium nitride, aluminum gallium nitride, indium nitride , indium gallium nitride, gallium arsenide, indium phosphide, zinc oxide, and zinc antimonide. 3. the manufacturing method based on the capacitive pressure sensor of ultra-thin film as claimed in claim 2 is characterized in that: when making described semiconductor compound thin film, it is carried out doping treatment, and the molding material of described substrate adopts semiconductor or pottery . 4. the manufacture method of the capacitive pressure sensor based on ultra-thin film as claimed in claim 2, is characterized in that: on described substrate, be prepared with insulating film, after etching each described cavity, described insulating film is bonded to on the outside of the semiconductor compound film. 5. the manufacture method of the capacitive pressure sensor based on ultra-thin film as claimed in claim 1, is characterized in that: when making graphene thin film, prepare copper film or nickel film earlier on described substrate, on described copper At least one layer of the graphene film is grown on the nickel film or the nickel film. 6. the manufacture method of the capacitive pressure sensor based on ultra-thin film as claimed in claim 1, is characterized in that: described insulating film is prepared on the described graphene film of outside, after etching each described cavity, described A base is bonded to the insulating film, and the base seals each of the cavities. 7. The manufacturing method of the capacitive pressure sensor based on ultra-thin film as claimed in claim 1, characterized in that: the material of the insulating film is silicon nitride, silicon dioxide, aluminum oxide, aluminum nitride, polymethyl One of methyl acrylate and polyimide. 8 . The method for manufacturing a capacitive pressure sensor based on an ultra-thin film according to claim 1 , wherein the thickness of the ultra-thin film ranges from nanometer to micron.