CN102798387B - The huge piezoresistive effect microthrust test of a kind of SOI base - Google Patents

Abstract

The invention discloses an SOI-based giant piezoresistive effect micro-gyroscope, which mainly includes a bonded substrate and a micro-gyroscope angular rate sensitive body. A rectangular bottom groove is etched in the middle of the upper surface of the bonding substrate; the micro-gyroscope angular rate sensitive body is arranged on the upper surface of the bonding substrate and connected with the bonding substrate. The micro-gyroscope angular rate sensitive body further includes: fixed comb-teeth electrode positive poles distributed on the left and right upper surfaces of the bonding substrate; comb-teeth electrode negative poles distributed on the front and rear sides; Tooth structure; the fixed seat provided on the upper surface of the negative electrode of the comb-toothed electrode; corresponding to the sensitive mass block above the bottom groove, damping holes are evenly distributed on the upper surface of the sensitive mass block; the sensitive mass block is connected to the fixed seat through a composite beam; the composite beam The root of the detection beam is equipped with a silicon nanowire resistor as a sensitive mechanism. The micromechanical gyroscope according to the embodiment of the present invention adopts an overall structural design, has a reasonable and compact structure, a simple detection circuit, is convenient to use, has good reliability, and is suitable for miniaturization.

Description

An SOI-Based Giant Piezoresistive Effect Microgyroscope

technical field

The invention relates to the research field of key components of micro-inertial navigation, in particular to an SOI-based micromechanical gyroscope with giant piezoresistive effect.

Background technique

At present, the commonly used detection methods for micromechanical gyroscopes are capacitive and piezoresistive. The piezoresistive type is based on the principle of piezoresistive effect of highly doped silicon. Since the resistance gauge coefficient of silicon piezoresistors is small, with the sensor size The varistors of the traditional doping process can no longer meet the requirements of modern high-sensitivity testing; the improvement of capacitive precision is to increase the capacitance area. Due to the miniaturization of the device, its accuracy is reduced by the reduction of the effective capacitance area. Difficult to improve.

The measurement of the angular velocity of the micro-mechanical gyroscope is completed by the detection device to realize the force-electric conversion. Its sensitivity and resolution are very important. Due to the miniaturization and integration of the gyroscope, the sensitive area of the detection is reduced accordingly, so the detection The sensitivity, resolution and other indicators of gyroscopes have reached the limit state of sensitive area detection, which limits the further improvement of gyroscope detection accuracy, and it is difficult to meet the needs of modern military and civilian equipment.

Contents of the invention

The present invention aims to solve at least one of the technical problems existing in the prior art.

In view of this, the present invention needs to provide a micromachined gyroscope, which is a SOI (Silicon-On-Insulator, silicon on an insulating substrate) micromachined gyroscope with a giant piezoresistive effect, which can at least improve the detection of a micromachined gyroscope. precision.

The invention provides a micromechanical gyroscope, comprising: a bonding substrate, the upper surface of the bonding substrate is etched with a bottom groove for providing movement for a sensitive mass; The rate sensitive body is set above the bonding substrate, and is firmly bonded to the bonding substrate, and the micro-gyroscope angular rate sensitive body includes: a fixed comb-tooth electrode positive electrode, which is arranged on the upper surface of the left and right sides of the bonding substrate; the comb-tooth electrode The negative electrode is arranged on the upper surface of the front and rear sides of the bonding substrate; the fixed comb is arranged on the upper surface of the positive electrode of the fixed comb electrode; the fixed seat is arranged on the upper surface of the negative electrode of the comb electrode; the sensitive mass is arranged above the bottom groove , with through-hole damping holes evenly distributed on the surface; the driving combs are set on the edges of the left and right sides of the sensitive mass and coincide with the fixed combs; the composite beam is used to connect the sensitive mass and the fixed seat; the silicon nanowire resistance Layer, as a sensitive mechanism, is set at the root of the detection beam of the composite beam.

The micromechanical gyro according to the embodiment of the present invention adopts an overall structural design, which is compact and reasonable, can not only make full use of space, but also suppress the influence of driving on detection, and is suitable for self-decoupling and miniaturization of devices. The silicon nanowire resistor is composed of a silicon nanowire resistor layer, a silicon nanowire resistor positive electrode, and a silicon nanowire resistor negative electrode. The giant piezoresistive effect of the silicon nanowire resistor layer is about 2 times higher than the piezoresistive sensitivity of traditional silicon piezoresistive devices. It can greatly improve the detection sensitivity and resolution of silicon piezoresistive sensors, and is an ideal method for improving silicon-based piezoresistive MEMS devices. In addition to the above features, the detection circuit of the micro-gyroscope angular rate sensitive body is simple in design, easy to use, good in reliability, and suitable for miniaturization.

According to an embodiment of the present invention, the bonding substrate has a rectangular structure as a whole, and a rectangular groove, that is, a bottom groove, is provided on it. Space can be provided for the up and down, left and right movements of the sensitive mass block of the micro-gyro angular rate sensitive body instrument.

According to an embodiment of the present invention, the micro-gyroscope angular rate sensitive body further includes: a fixed positive electrode of the comb electrode, and two fixed positive electrodes of the fixed comb electrode are respectively placed on the left and right frames of the bonding substrate The surface of the electrode is firmly bonded, and the upper surface of the electrode is provided with fixed comb teeth, which are firmly bonded; the negative electrode of the comb electrode is the electrode that drives the comb teeth on the left and right sides of the sensitive mass. It is on the same plane as the positive electrode of the fixed comb electrode, placed on the upper surface of the front and rear frames of the bonding substrate, and bonded firmly, and the upper surface of the electrode is provided with a fixed seat, and bonded firmly; the sensitive mass, the sensitive Through-hole damping holes are evenly distributed on the surface of the mass block. Driving combs are evenly distributed on the left and right edges of the sensitive mass, and the sensitive mass is connected to the fixed seat through a composite beam. A composite beam, the composite beam is composed of a drive beam, a detection beam, and a connecting block, and is used to connect the fixed seat and the sensitive mass block, and the upper surface of the detection beam is provided with a silicon nanowire resistor.

According to an embodiment of the present invention, the fixed comb electrode is provided with a base for the fixed comb; the negative electrode of the comb electrode is provided with the fixed seat, and the fixed seat has front and rear two One, respectively placed on the upper surface of the two comb-teeth electrode negative electrodes, and connected with the sensitive mass block through the composite beam; the upper surface of the connection part between the fixed seat and the composite beam is provided with a silicon nanowire resistance electrode.

According to an embodiment of the present invention, the sensitive mass is rectangular, embedded in the bottom groove of the bonding substrate, and can move up, down, forward, backward, left and right in the bottom groove; the The front and rear symmetrical positions of the sensitive mass are respectively connected to the fixed seat through the composite beam.

According to an embodiment of the present invention, the composite beam is in a folded shape, the driving beam and the detection beam are connected through a connecting block, the two ends of the connecting block are drive beams in the shape of a "ji", and the detection beam is arranged in the middle of the connecting block; the composite beam The thickness of the driving beam in the middle is the same as that of the sensitive mass block, the thickness of the detecting beam is smaller than that of the driving beams on both sides, and silicon nanowire resistors are arranged on the upper surface of the root of the detecting beam near the end of the fixed seat.

According to an embodiment of the present invention, the fixed combs coincide with the driving combs on both sides of the sensitive mass.

According to an embodiment of the present invention, the four-corner symmetrical position of the sensitive mass is processed with a composite beam movement space, and the composite beams are respectively embedded in the composite beam movement space, and the composite beam can move up and down, left and right, forward and backward in the composite beam movement space sports.

According to an embodiment of the present invention, a silicon dioxide layer is formed on the silicon substrate layer of the detection beam, and a folded silicon nanowire resistance layer is formed on the silicon dioxide layer. The two ends of the silicon nanowire resistance layer are respectively The positive electrode of the silicon nanowire resistor and the negative electrode of the silicon nanowire resistor are connected.

According to an embodiment of the present invention, the silicon nanowire resistance layer is made of SOI material.

Description of drawings

The above and/or additional aspects and advantages of the present invention will become apparent and comprehensible from the description of the embodiments in conjunction with the following drawings, wherein:

Fig. 1 is the perspective view of the overall structure of the embodiment of the present invention;

Fig. 2 is the overall structural plan view of the embodiment of the present invention;

3 is a three-dimensional structure diagram of a micro-gyroscope angular rate sensitive body according to an embodiment of the present invention;

Fig. 4 is a plane structure diagram of a sensitive mass block according to an embodiment of the present invention;

5 is a three-dimensional structure diagram of a bonded substrate according to an embodiment of the present invention;

Fig. 6 is the silicon nanowire resistance structural diagram of the embodiment of the present invention;

Fig. 7 is a three-dimensional structure diagram of a composite beam according to an embodiment of the present invention;

Fig. 8 is a three-view view of a composite beam according to an embodiment of the present invention;

Fig. 9 is a structure diagram of a fixed comb according to an embodiment of the present invention;

As shown in the figure, the list of reference signs is as follows:

1. Sensitive mass, 2. Damping hole, 3. Fixed seat, 4. Fixed comb base, 5. Fixed comb, 6. Silicon nanowire resistor, 7. Silicon nanowire resistor positive electrode, 8. Silicon nanowire Resistor negative electrode, 9, driving comb teeth, 10, composite beam movement space, 11, driving beam, 12, detection beam, 13, connecting block, 14, comb teeth, 15, comb tooth groove, 16, comb tooth electrode negative pole, 17 , positive electrode of fixed comb electrode, 18, silicon substrate layer, 19, silicon dioxide layer, 20, silicon nanowire resistance layer, 21, bonding substrate, 22, bottom groove, 23, micro-gyroscope angular rate sensitive body, 24, composite beam

detailed description

Embodiments of the present invention are described in detail below, examples of which are shown in the drawings, wherein the same or similar reference numerals designate the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the figures are exemplary only for explaining the present invention and should not be construed as limiting the present invention.

In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right" etc. are based on those shown in the accompanying drawings. Orientation or positional relationship is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention.

In the description of the present invention, it should be noted that unless otherwise specified and limited, the terms "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral Ground connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediary, and it can be the internal communication of two components. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention in specific situations.

Silicon nanowire resistors are a new type of silicon piezoresistive resistors. The gauge coefficient of the giant piezoresistive effect represented by it is as high as 5000, which is about 2 times higher than that of silicon piezoresistors processed by traditional bulk (about 100). Magnitude. The application of this new type of silicon nanowire resistance to the research of micromechanical gyroscope is the inheritance and breakthrough of the traditional piezoresistive micromechanical gyroscope.

The present invention will be further described below in conjunction with accompanying drawing:

As shown in Figures 1-2, the micromechanical gyroscope according to an embodiment of the present invention includes two parts: a bonding substrate 21 and a microgyroscope angular rate sensitive body 23;

Specifically, the bonding substrate 21 can be used as a carrier, for example, the bonding substrate 21 can be made of a semiconductor material, and a bottom groove 22 is provided at the center of the upper surface of the bonding substrate 21 to provide a movement space for the sensitive mass.

The micro-gyroscope angular rate sensitive body 23 can be arranged on the upper surface of the bonding substrate 21 and be connected to the bonding substrate 21, and the micro-gyroscope angular rate sensitive body 23 can include: a sensitive mass 1 disposed on the bottom groove 22 , and the two are spaced apart, the sensitive mass 1 can vibrate up and down, left and right, front and back in the bottom groove 22; the fixed comb 5 is arranged on the upper surface of the positive electrode 17 of the fixed comb electrode, and is firmly bonded, and fixed The comb teeth 5 and the sensitive mass block 1 are on the same plane; the driving comb teeth 9 are arranged on the left and right sides of the sensitive mass block 1, the comb teeth are evenly distributed, and coincide with the fixed comb teeth 5, and the two can be separated under the action of electrostatic force. Drive the sensitive mass 1 to make it vibrate left and right.

The micromechanical gyro according to the embodiment of the present invention adopts an overall structural design, which is reasonable and compact, can not only make full use of space, but also suppress the influence of driving on detection, and is suitable for self-decoupling and miniaturization of devices. Under the driving force of the electrostatic comb teeth 9, the sensitive mass 1 performs linear simple harmonic vibration along the X-axis direction. When the gyroscope has an angular velocity input in the Y-axis direction, due to the Coriolis force, the sensitive mass 1 will Precession is generated in the Z-axis direction. This precession will drive the composite beam 24 to deform the detection beam 12 , thereby causing the silicon nanowire resistance layer 20 fabricated at the root of the detection beam 12 to deform. Since the silicon nanowire resistance layer 20 has a giant piezoresistive effect, a slight deformation can cause a drastic change in the resistance value of the nanowire resistance layer. In this way, a weak Coriolis force signal can be converted into a strong electrical signal, and the magnitude of the input angular velocity in the Y-axis direction can be detected by processing the signal. The detection circuit design of this device is simple, easy to use, good reliability, suitable for miniaturization

As shown in Figure 3, according to an embodiment of the present invention, the micro-gyroscope angular rate sensitive body 23 further includes: a sensitive mass 1, a fixed base 3, a fixed comb 5, a combined beam 24, a negative electrode 16 of a comb electrode, a fixed comb Electrode Positive 17 .

Specifically, there are two fixed comb-teeth electrode positive electrodes 17, which are respectively placed on the upper surface of the left and right frames of the bonding substrate 21 and bonded firmly, and the upper surface of the electrode is provided with fixed comb teeth 5, and bonded firm; the comb-teeth electrode negative pole 16 is the electrode that drives the comb teeth 9 on the left and right sides of the sensitive mass 1, and the electrode is on the same plane as the fixed comb-teeth electrode positive pole 17, and is placed on the front and rear frames of the bonding substrate 21 The upper surface of the electrode is firmly bonded, and the upper surface of the electrode is provided with a fixing seat 3, which is firmly bonded; the surface of the sensitive mass 1 is evenly distributed with through-hole damping holes 2. Driving combs 9 are evenly distributed on the left and right edges of the sensitive mass 1 , and the sensitive mass 1 is connected to the fixed seat 3 through the composite beam 24 . The composite beam 24 is composed of a driving beam 11 , a detection beam 12 , and a connecting block 13 , and is used for connecting the fixed seat and the sensitive mass. The upper surface of the detection beam 12 is provided with a silicon nanowire resistor 6 .

As shown in FIG. 4 , according to an embodiment of the present invention, the sensitive mass 1 is rectangular, connected to the inner four corners of the fixed seat 3 through a combined beam 24, and embedded in the bottom groove 22 on the upper surface of the bonding substrate 21; The shape of the four-corner symmetric position of the composite beam 24 is just in line with the shape of the outer frame of the composite beam 24, and the composite beam 4 can move up and down, forward and backward, left and right in the composite beam motion space 10; the sensitive mass 1 can be made of a semiconductor Made of material, under the support of the composite beam 24, it can vibrate back and forth, left and right, and up and down in this bottom groove 22; the surface of the sensitive mass 1 is evenly distributed with through-hole damping holes 2; the damping holes 2 penetrate through the sensitive mass 1, and damping The holes 2 can be circular or square, and the number and size of the damping holes 2 can be determined according to the application environment and the damping coefficient.

As shown in FIG. 5 , according to an embodiment of the present invention, the bonded substrate 21 is rectangular, and a bottom groove 22 is made at the center of the upper surface. The bottom groove 22 can provide a movement space for the sensitive mass 1 to move up, down, left, and right.

As shown in FIG. 6, according to an embodiment of the present invention, a silicon dioxide layer 19 is arranged on a silicon substrate 18, a silicon nanowire resistor 6 is arranged on the silicon dioxide layer 19, and the two ends of the silicon nanowire resistor 6 The silicon nanowire resistor positive electrode 7 and the silicon nanowire resistor negative electrode 8 are respectively connected; the silicon nanowire resistor layer 20 is made of SOI material, and the upper silicon structure is doped to form a silicon nanowire resistor with giant piezoresistive effect. The width of the wire resistance layer 20, the size of the length and the number of turns will depend on the design parameters of the micromachined gyroscope and the application environment; The two ends are well treated to form a good ohmic contact with the positive electrode 7 of the silicon nanowire resistor and the negative electrode 8 of the silicon nanowire resistor.

As shown in FIGS. 7-8 , according to an embodiment of the present invention, the combined beam 24 includes: a driving beam 11 , a detecting beam 12 , and a connecting block 13 . The end of the combined beam 24 is a connection block 13, and the drive beam 11 is symmetrically arranged on the left and right parts of the connection block 13, and the detection beam 12 is between the two drive beams 11, and the end of the detection beam 12 is connected to the connection block 13, and the three are integrated structure. The thickness of the driving beam 11 is the same as that of the connecting block 13 , the thickness of the detection beam 12 is smaller than that of the driving beam 11 and the connecting block 13 , and the thickness of the connecting block 13 and the driving beam 11 is the same as that of the sensitive mass 1 . Ensure that the total stiffness of the detection beam 12 in the Z-axis direction is also far less than the total stiffness of the drive beam 11 in the Z-axis direction, so that the angular rate sensitive body of the micro-gyroscope can be adjusted in the driving direction, that is, the X-axis direction, and the detection direction, that is, the Z-axis direction. Self-decoupling in the axial direction; a silicon nanowire resistance layer 20 is provided on the upper surface of the root of the detection beam 12 near the end of the fixing seat 3, and this structure is the sensitive structure of the gyroscope.

As shown in Figure 9, according to an embodiment of the present invention, the fixed comb includes: fixed comb base 4, comb 14, comb groove 15, the fixed comb base 4 is bonded to the positive electrode of the fixed comb Above 17, one side of the fixed comb teeth 5 is equidistantly provided with comb teeth 14, between the comb teeth 14 are comb teeth grooves 15, and the comb teeth 14, the comb teeth grooves 15 are cross-connected with the driving comb teeth 9 on the sensitive mass 1 , the thickness of the fixed comb 5 is the same as that of the sensitive mass 1 .

In the description of this specification, references to the terms "one embodiment," "some embodiments," "exemplary embodiments," "example," "specific examples," or "some examples" are intended to mean that the implementation A specific feature, structure, material, or characteristic described by an embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Although the embodiments of the present invention have been shown and described, those skilled in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the invention is defined by the claims and their equivalents.

Claims (9)

1. A micro-mechanical gyroscope, characterized in that, said micro-mechanical gyroscope is based on SOI substrate giant piezoresistive effect, specifically comprising: A bonded substrate, the upper surface of the bonded substrate is provided with a rectangular groove, that is, a bottom groove; The micro-gyro angular rate sensitive body, the micro-gyro angular rate sensitive body is arranged above the bonding substrate, and is firmly bonded to the bonding substrate, and the micro-gyro angular rate sensitive body includes: the left and right upper surfaces of the bonding substrate The positive electrode of the fixed comb electrode is distributed; the negative electrode of the comb electrode is distributed on the upper surface of the front and rear sides; the fixed comb structure is arranged on the upper surface of the positive electrode of the fixed comb electrode; The sensitive mass block above the groove has through-hole damping holes evenly distributed on the sensitive mass block; the sensitive mass block is connected to the fixed seat through the composite beam; the root of the detection beam of the composite beam is equipped with a silicon nanowire resistor as a sensitive mechanism; The positive pole of the fixed comb-teeth electrode, the positive pole of the fixed comb-teeth electrode is two, respectively placed on the upper surface of the left and right frames of the bonding substrate and bonded firmly, and the upper surface of the fixed comb-teeth electrode positive pole is provided with fixed comb teeth, and firmly bonded; The negative electrode of the comb-teeth electrode, the negative electrode of the comb-teeth electrode is the electrode that drives the comb teeth on the left and right sides of the sensitive mass block, the electrode is on the same plane as the positive electrode of the fixed comb-teeth electrode, and placed on the upper surface of the front and rear frames of the bonding substrate , and the bonding is firm, and the upper surface of the electrode is provided with a fixing seat, and the bonding is firm; Sensitive mass, the surface of the sensitive mass is evenly distributed with through-hole damping holes, driving comb teeth are evenly distributed on the left and right sides of the sensitive mass, and the sensitive mass is connected to the fixed seat through a composite beam; A composite beam, the composite beam is composed of a driving beam, a detection beam, and a connecting block, and is used to connect the fixed seat and the sensitive mass block. 2. The micro-mechanical gyroscope according to claim 1, wherein the bonding substrate as a whole has a rectangular structure, which can provide space for the up-down, left-right movement of the sensitive mass of the micro-gyro angular rate sensitive body instrument. 3. The micromechanical gyroscope according to claim 1, characterized in that, the positive electrode of the fixed comb electrode is provided with the base of the fixed comb; the negative electrode of the comb electrode is provided with the There are two fixed seats, the front and the back, which are respectively placed on the upper surfaces of the negative electrodes of the two comb-toothed electrodes, and connected to the sensitive mass block through the combined beam; the upper surface of the fixed seat and the combined beam is provided with a silicon nanometer Wire resistance electrodes. 4. The micromechanical gyroscope according to claim 1, wherein the sensitive mass is rectangular, and is embedded in the bottom groove of the bonding substrate, and can be moved up, down and forward in the bottom groove. , backward and left and right movements; the front and rear symmetrical positions of the sensitive mass are respectively connected to the fixed seat through the composite beam. 5. The micromechanical gyroscope according to claim 1, wherein the combined beam is in a folded shape, the drive beam and the detection beam are connected through a connecting block, and the two ends of the connecting block are drive beams in the shape of a "several", connected A detection beam is arranged in the middle of the block; the thickness of the driving beam in the combined beam is the same as that of the sensitive mass block, the thickness of the detection beam is smaller than that of the driving beams on both sides, and a silicon nanowire resistor is arranged on the upper surface of the root of the detection beam near the end of the fixed seat. 6 . The micromechanical gyroscope according to claim 1 , wherein the fixed combs coincide with the driving combs on both sides of the sensitive mass. 7 . 7. The micromechanical gyroscope according to claim 4, wherein the four-corner symmetrical position of the sensitive mass is processed with a combined beam movement space, the combined beams are respectively embedded in the combined beam movement space, and the combined beam can be combined The beam moves up and down, left and right, forward and backward in the movement space. 8. The micromachined gyroscope according to claim 5, characterized in that, a silicon dioxide layer is made on the silicon substrate layer of the detection beam, a silicon nanowire resistance layer is made on the silicon dioxide layer, and the silicon nanowire Both ends of the resistance layer are respectively connected with a silicon nanowire resistor positive electrode and a silicon nanowire resistor negative electrode. 9. The micromechanical gyroscope according to claim 8, wherein the silicon nanowire resistance layer is made of SOI material.