CN104215231A - MEMS high precision resonant beam closed-loop control gyroscope and manufacturing process thereof - Google Patents

Abstract

The invention provides an MEMS (micro-electromechanical system) high precision resonant beam closed-loop control gyroscope, which includes a measurement body, an upper cover plate and a lower cover plate. The measurement body comprises a pedestal, a coupling frame, a mass block connected to the coupling frame, and a fixation block. The pedestal and the fixation block and the fixation block are in fixed connection with the upper cover plate and the lower cover plate. The mass block and the coupling frame are connected through a plurality of elastic beams. A first comb coupling structure is arranged between the mass block and the fixation block. One side of the coupling frame is provided with support beams. The coupling frame is connected to the pedestal through the support beams. The upper part and the lower part of the coupling frame's side wall are respectively provided with a resonant beam, one ends of the resonant beams are connected to the coupling frame and the other ends are connected to the pedestal respectively. Second comb coupling structures are arranged between the resonant beams and the pedestal. And the pedestal and the second comb coupling structures are used for detecting the rotational angular velocity.

Description

A MEMS high-precision resonant beam closed-loop control gyroscope and its manufacturing process

technical field

The invention relates to the field of sensors, in particular to a gyroscope

Background technique

Gyroscopes can detect the angle and direction of an object's tilt, and have been used in many fields, such as ships and airplanes. With the continuous advancement of microelectromechanical systems (MEMS) technology, many small nanoscale gyroscopes will be commercialized and widely used in automobiles, robots, mobile phones, mobile devices and other fields.

Unlike conventional gyroscopes, MEMS gyroscopes have no rotating parts and do not require bearings. MEMS gyroscopes use the concept of sensing angular velocity of vibrating objects. Vibration is used to induce and detect the Coriolis force. For example, the Chinese invention patent application with the publication number CN101180516 uses a driver to accelerate multiple mass blocks in the X direction. When the gyroscope rotates with an angular velocity of Ω on the Z axis, the mass blocks will be generated in the Y direction according to the following formula: Coriolis force F _cori . The gyroscope detects the Coriolis force in the Y direction, so that the rotational angular velocity Ω can be calculated.

F _cori =2mΩv

Among them, m is the mass of the mass block, and v is the velocity.

Common MEMS gyroscopes, such as the Chinese utility model patent with the notification number CN201828268U, detect the change in capacitance caused by the displacement of the mass to calculate the rotational angular velocity. However, the capacitance change is not a digital signal, so the integrated circuit also needs to perform a series of processing steps such as filtering, noise reduction, and signal conversion on the detected results. This increases the complexity of the integrated chip, and also increases the design and manufacturing costs of the integrated chip. In addition, in the signal processing process, there will be distortion, loss and so on.

For example, the Chinese invention patent application with the publication number CN101135563 amplifies the Coriolis force to the tuning fork resonators arranged on both sides of the frame through a two-stage lever, and measures the rotational angular velocity through tuning. Although the output of the tuning fork resonator is a digital signal, due to the limitation of the manufacturing process, there will be errors in the size of the lever, and the size of the two mass blocks may not be the same, so a certain error signal will be generated; and the double mass is manufactured on the same plane Blocks, levers, and tuning fork resonators increase the overall chip area and reduce system integration.

Contents of the invention

The technical problem to be solved by the present invention is to overcome the deficiencies of the above-mentioned prior art, and provide a gyroscope capable of outputting digital signals and having high sensitivity.

A MEMS high-precision resonant beam closed-loop control gyroscope, including: a measuring body, an upper cover plate and a lower cover plate, the measuring body includes a base, a coupling frame, a quality block connected to the coupling frame, and a mass block located on the mass block The fixed block in the center; the base and the fixed block are fixedly connected with the upper cover plate and the lower cover plate; the mass block is connected with the coupling frame through a plurality of elastic beams; the mass A first comb-shaped coupling structure is set between the block and the fixed block; a support beam is set on one side of the coupling frame; the coupling frame is connected to the base through the support beam; the coupling frame The upper and lower parts of the side wall are respectively provided with resonant beams, one end of the resonant beam is connected with the coupling frame, and the other end is respectively connected with the base; the resonant beam and the base are also provided with a second Two comb-shaped coupling structures; the resonant beam and the second comb-shaped coupling structure are used to detect rotational angular velocity.

Gyroscope among the present invention also comprises following accessory feature:

The support beam and the resonant beam are elastic beams.

The mass block is a square body hollowed out in the center.

The elastic beam is a U-shaped elastic beam.

The elastic beams are arranged at four end corners of the mass block.

The first comb-shaped coupling structure is disposed in a space between the mass block and the fixed block.

Electrodes are arranged on the proof mass, the upper cover plate, the lower cover plate, the first comb-like coupling structure and the second coupling structure.

The resonant beam and the support beam are arranged on the same side of the coupling frame.

A groove is provided on the base, and the resonant beam is located in the groove.

The resonant beams are two groups of upper and lower groups, and each group of resonant beams includes two resonant beams, and two pairs of the second comb-shaped coupling structures are arranged between each resonant beam and the base; The second comb-shaped coupling structure is used to drive the resonant beam, and the other pair is used to detect the rotational angular velocity.

The second comb-shaped coupling structure includes two matching comb teeth, one of which is connected to the resonant beam, and the other comb is connected to the base.

The measuring body adopts a double-layer silicon structure including an upper silicon layer and a lower silicon layer, and a buried oxide layer is arranged between each silicon layer.

The resonant beam and the elastic beam are formed on the upper silicon layer.

A kind of manufacturing process of gyroscope, it is characterized in that, described manufacturing process comprises the following steps:

The first step is to form a silicon dioxide layer on the front and back of the epitaxial silicon silicon wafer on the first insulator through high-temperature oxidation or deposition treatment;

In the second step, through photolithography and etching, a plurality of holes deep to the upper silicon layer are etched on the silicon dioxide layer on the front side of the first silicon-on-insulator epitaxial silicon wafer;

The third step is to deposit a silicon nitride layer on the front and back of the epitaxial silicon wafer on the first insulator;

The fourth step is to remove the silicon nitride layer and silicon dioxide layer on the positions corresponding to the support beams in the front of the first epitaxial silicon-on-insulator silicon wafer respectively by photolithography and etching, and remove the upper silicon layer Etching to the buried oxide layer; meanwhile, the silicon nitride layer and the silicon dioxide layer on the positions corresponding to the elastic beams, resonant beams, and the gap between the fixed block and the mass block in the back of the first epitaxial silicon silicon wafer on insulator removing the silicon layer, and etching the lower silicon layer to the buried oxide layer;

The fifth step is to remove the buried oxide layer by etching to form a layer of elastic beams and resonant beams;

The sixth step is to further etch to a certain depth the position corresponding to the support beam in the front surface of the epitaxial silicon-on-insulator silicon wafer to form a support beam;

The seventh step is to form a layer of silicon dioxide on the front and back of the epitaxial silicon wafer on the second insulator through high temperature oxidation or deposition treatment;

In the eighth step, through photolithography and etching, a plurality of holes deep to the upper silicon layer are etched on the silicon dioxide layer on the front side of the second epitaxial silicon-on-insulator wafer;

The ninth step is to deposit a layer of silicon nitride on the front and back of the epitaxial silicon wafer on the second insulator;

In the tenth step, through photolithography and etching, silicon nitride on the positions corresponding to the support beams, elastic beams, resonant beams, and the gap between the fixed block and the mass block on the back of the second silicon-on-insulator epitaxial silicon wafer layer and the silicon dioxide layer are removed, and the lower silicon layer is etched to the buried oxide layer;

In the eleventh step, the buried oxide layer is removed by etching;

In the twelfth step, the silicon nitride layer and the silicon dioxide layer on the back of the epitaxial silicon wafer on the first and second insulators are respectively removed;

In the thirteenth step, perform back-to-back silicon-silicon bonding on the first and second epitaxial silicon-on-insulator wafers to form a base, a fixed block, a mass block, and a coupling frame;

In the fourteenth step, the bond and the silicon nitride layer on the front side of the silicon wafer are removed;

The fifteenth step is to deeply etch the bond and the exposed upper silicon layer on the front side of the rear silicon wafer to form through holes, thereby forming free upper elastic beams, resonant beams, upper first comb-like coupling structures and upper upper first combs. Two-comb coupling structure;

In the sixteenth step, the silicon dioxide layer on the front side of the bond and the back silicon wafer is removed;

The seventeenth step is to bond the key and the front side of the rear silicon chip to the upper cover;

In the eighteenth step, the bond and the silicon nitride layer on the back of the silicon wafer are removed;

The nineteenth step is to deeply etch the bond and the exposed upper silicon layer on the back of the back silicon wafer to form through holes, thereby forming freely movable support beams, lower elastic beams, lower resonant beams, and the first comb-like coupling of the lower layer. structure and the second comb-like coupling structure in the lower layer;

The twentieth step is to remove the bond and the silicon dioxide layer on the back of the silicon wafer;

In the twenty-first step, bond the key and the back of the back silicon chip with the lower cover; form a complete gyroscope;

The processing technology for the upper cover plate and the lower cover plate also includes:

A. Forming a recessed area on the bonding surface of the upper cover plate and the lower cover plate by photolithography, deep etching and etching respectively;

B. Depositing metal on the upper cover and the lower cover to form electrodes;

C. Before bonding with the epitaxial silicon wafer on the insulator, cleaning the upper cover silicon wafer and the lower cover silicon wafer;

The deep etching and the etching method are one or more of the following methods: dry etching or wet etching, and the dry etching includes: deep reactive ion etching of silicon and reactive ion etching.

The etchant used to etch the silicon layer is one or more of the following etchant combinations: potassium hydroxide, tetramethylammonium hydroxide, ethylenediamine phosphoquinone or gaseous xenon difluoride.

The etchant used for etching the silicon dioxide layer is one or a combination of the following etchant: buffered hydrofluoric acid, 49% hydrofluoric acid or gaseous hydrogen fluoride.

The gyroscope and its manufacturing process provided by the present invention have the following advantages: First, the present invention detects the angular velocity of rotation by detecting the frequency change of the resonant beam, and the output of the frequency change is a digital signal without filtering, signal Conversion and other processes are convenient for docking with other signal processors, and the influence of circuit noise on the detection results is also reduced. Make the gyroscope work more stable. Secondly, the structure of setting two sets of resonant beams up and down in the vertical direction is to output the frequency change in the form of differential. Such an output signal can obtain twice the frequency output. At the same time, the differential output also eliminates the influence of temperature on the resonant beams. In addition, the gyroscope is equipped with a feedback control system in the detection direction. When the integrated circuit calculates the displacement of the mass block from the signal detected by the second comb-shaped coupling structure on the resonant beam, the feedback control system will apply a force to the mass block. Feedback voltage, thereby maintaining the mass in an equilibrium position. The feedback control system can effectively enhance the stability of the system, reduce the nonlinearity of the system, widen the bandwidth of the system, and shorten the reaction time, thereby making the detection more accurate. Finally, a larger mass is obtained by bonding, which improves the sensitivity.

Description of drawings

Fig. 1 is a structural schematic diagram of the present invention.

Fig. 2 is a perspective view of the measuring body in the present invention.

Fig. 3 is an enlarged view of A in Fig. 2 .

Fig. 4 is an enlarged view of B in Fig. 2 .

Fig. 5 is an enlarged view of point C in Fig. 2 .

Fig. 6 is a top view of the measuring body in the present invention.

Fig. 7 is a schematic cross-sectional view of the first to fourth steps of the manufacturing method along the line AA' in Fig. 6 .

Fig. 8 is a schematic cross-sectional view along line BB' in Fig. 6 from the first step to the fourth step of the manufacturing method.

Fig. 9 is a schematic cross-sectional view of the fifth to seventh steps of the manufacturing method along the line AA' in Fig. 6 .

Fig. 10 is a schematic cross-sectional view of the fifth step to the seventh step of the manufacturing method along line BB' in Fig. 6 .

Fig. 11 is a schematic cross-sectional view of the eighth step to the eleventh step of the manufacturing method along the line AA' in Fig. 6 .

Fig. 12 is a schematic cross-sectional view of the eighth step to the eleventh step of the manufacturing method along the line BB' in Fig. 6 .

Fig. 13 is a schematic cross-sectional view of the twelfth to fourteenth steps of the manufacturing method along the line AA' in Fig. 6 .

Fig. 14 is a schematic cross-sectional view of the twelfth to fourteenth steps of the manufacturing method along line BB' in Fig. 6 .

Fig. 15 is a schematic cross-sectional view of the fifteenth to seventeenth steps of the manufacturing method along the line AA' in Fig. 6 .

Fig. 16 is a schematic cross-sectional view of the fifteenth to seventeenth steps of the manufacturing method along line BB' in Fig. 6 .

Fig. 17 is a schematic cross-sectional view of the eighteenth to the twentieth steps of the manufacturing method along the line AA' in Fig. 6 .

Fig. 18 is a schematic cross-sectional view of the eighteenth to the twentieth steps of the manufacturing method along line BB' in Fig. 6 .

Fig. 19 is a schematic cross-sectional view of the twenty-first to twenty-second steps of the manufacturing method along the line AA' in Fig. 6 .

Fig. 20 is a schematic cross-sectional view of the twenty-first to twenty-second steps of the manufacturing method along line BB' in Fig. 6 .

Fig. 21 is a schematic cross-sectional view of the twenty-third step of the manufacturing method along the line AA' in Fig. 6 .

Fig. 22 is a schematic cross-sectional view of the 23rd step of the manufacturing method along line BB' in Fig. 6 .

Detailed ways

Below in conjunction with accompanying drawing, the present invention is described in further detail:

Referring to Fig. 1, a kind of gyroscope comprises: measuring body 1, the upper cover plate 2 that is connected with described measuring body 1 and the lower cover plate 3; Described measuring body 1 is bonded by two pieces of epitaxial silicon on insulator The epitaxial silicon-on-insulator structure is referred to as the SOI structure, which includes an upper silicon layer 4 and a lower silicon layer 5 ; a buried oxide layer 6 is provided between the upper silicon layer 4 and the lower silicon layer 5 .

1 to 6, the measuring body 1 includes a base 11, a coupling frame 12, a mass 13 connected to the coupling frame 12, and a fixed block 14 at the center of the mass 13; the base 11 And the fixed block 14 is fixedly connected with the upper cover plate 2 and the lower cover plate 3; one side of the coupling frame 12 is provided with a support beam 15; the coupling frame 12 is connected with the support beam 15 The base 11 is connected; the mass block 13 is connected to the coupling frame 12 through a plurality of elastic beams 16; wherein, the support beams 15 are elastic beams. When the Coriolis force occurs, the mass block 13 will move in the vertical direction, and the movement of the mass block 13 will drive the coupling frame 12 to swing up and down through the elastic beam 16 .

Referring to Fig. 1 to Fig. 6, preferably, the measuring body 1 is formed by bonding two silicon wafers, the base 11 is a hollowed out square body, and the coupling frame 12, the mass block 13 and the fixed block 14 are all located on the base 11. Inside the hollow.

Referring to Fig. 1 to Fig. 6, preferably, the mass block 13 is a square body with a hollow center, and the elastic beam 16 is a U-shaped beam, and is arranged on the four corners of the mass block 13, so that the mass block 13 can drive The displacement of the coupling frame 12 in the vertical direction. In addition, a first comb-like coupling structure 17 is also provided in the space between the mass block 13 and the fixed block 14 . The two sets of comb teeth 171 of the first comb-shaped coupling structure 17 are respectively connected to the mass block 13 and the fixed block 14 . The first comb-like coupling structure 17 is used to drive the mass block 13 to vibrate back and forth in the horizontal direction.

1 to 6, resonant beams 18 are arranged on the upper and lower parts of the side walls of the coupling frame 12, one end of the resonant beam 18 is connected to the coupling frame 12, and the other end is connected to the base 11 respectively. Connection; preferably, a groove 111 is further provided on the base 11 , one end of the resonant beam 18 is connected to the coupling frame 12 , and the other end is connected to the end of the groove 111 . A second comb-shaped coupling structure 19 is also provided between the resonant beam 18 and the base 11 . The comb teeth 191 of the second comb-shaped coupling structure 19 are respectively connected to the resonant beam 18 and the base 11 . In one embodiment of the present invention, each resonant beam 18 is provided with two sets of comb teeth 191 , one set is used to drive the resonant beam 18 to vibrate, and the other set is used to detect the vibration frequency of the resonant beam 18 . The number of resonant beams 18 is two groups, which are respectively set up and down on the side walls of the coupling frame 12 and are on the same vertical plane. There are two resonant beams 18 in each group of resonant beams 18 . However, the number and arrangement of the resonant beams 18 and the second comb-shaped coupling structures 19 are not limited to this embodiment.

Referring to FIG. 1 to FIG. 6 , the gyroscope is provided with electrodes on both the first comb-shaped coupling structure 17 and the second comb-shaped coupling structure 19 . In operation, the integrated circuit applies a voltage to the first comb coupling structure 17 , thereby driving the mass block 13 to vibrate back and forth in the X-axis direction relative to the fixed block 14 . At the same time, the integrated circuit will also apply a voltage to one of the two pairs of second comb-shaped coupling structures 19 to drive the resonant beam 18 to vibrate at a certain frequency. The amplitude and frequency of the voltages output by the two pairs of second comb-shaped coupling structures 19 for driving are the same. Therefore, when the resonant beam 18 is not subjected to the stress in the axial direction, the two groups of resonant beams 18 at the upper and lower The vibration frequency should be exactly the same. When the Y-axis rotation angular velocity occurs, the mass block 13 driven by the first comb coupling structure 17 will generate a Coriolis force in the vertical direction, that is, the Z-axis direction, and the Coriolis acceleration will cause the mass block 13 to displace up and down. Since the coupling frame 12 and the mass block 13 are connected through the elastic beam 16, the coupling frame 12 will also be displaced in the vertical direction. The support beam 15 arranged on one side of the coupling frame 12 is fixedly connected with the base 11 , so that the coupling frame 12 can swing in the vertical direction with the support beam 15 as the axis. The up and down swing of the coupling frame 12 will cause the upper and lower groups of resonant beams 18 to be subjected to stresses of equal magnitude and opposite directions in the axial direction, so that the vibration frequency of the upper and lower groups of resonant beams 18 will increase one and decrease, and the vibration frequency of the two groups will increase. The frequency changes are equal. The second comb-shaped coupling structure 19 can read out the frequency change, and then the integrated circuit subtracts the two frequencies in a differential form to obtain an output signal with twice the frequency change range, and then calculate the rotational angular velocity. Since the frequency difference output signal is a digital signal, it is convenient to connect with other signal processors. At the same time, when the gyroscope is affected by temperature, the vibration frequency of the upper and lower two groups of resonant beams 18 will increase or decrease at the same time, resulting in amplitude Equal, the deviation of the same direction of change, the influence of temperature on the gyroscope can be eliminated through the form of differential subtraction. In addition, preferably, the mass block 13, the upper cover plate 2 and the lower cover plate 3 are respectively provided with electrodes, when the integrated circuit calculates the swing direction of the mass block 13 and the coupling frame 12 according to the detection result of the second comb-shaped coupling structure 19 and the swing amplitude, a feedback voltage will be applied to the upper cover plate 2 or the lower cover plate 3 according to the swing direction and amplitude, and the mass block 13 and the coupling frame 12 will return to the equilibrium position, thereby forming a feedback control system and effectively enhancing the stability of the system. Stability, reduce the nonlinearity of the system, widen the system bandwidth, shorten the reaction time, and make the detection more accurate.

Next, the manufacturing process for manufacturing the gyroscope in the present invention will be described in detail according to FIGS. 6 to 22, including the following steps:

The first step is to perform high-temperature oxidation treatment on the front and back surfaces of SOI silicon wafer A, and form a layer of silicon dioxide layer 7 on the front and back surfaces respectively; or use chemical vapor deposition (CVD) to deposit silicon dioxide on the front and back surfaces. Build up a silicon dioxide layer 7;

In the second step, the front and back of the SOI silicon wafer A are coated with photoresist, then exposed according to a specific pattern, and developed with a developer. This way the exposed pattern will appear. Reactive ion dry etching or buffered hydrofluoric acid is used to etch the silicon dioxide layer 7 on the front and back sides of the SOI silicon wafer A to form a plurality of holes deep to the upper silicon layer 4;

In the third step, a silicon nitride layer 8 is deposited on the front and back sides of the SOI silicon wafer A by chemical vapor deposition;

The fourth step is to coat the front and back of the SOI silicon wafer A with photoresist, then expose it according to a specific pattern, and develop it with a developer. This way the exposed pattern will appear. Reactive ion dry etching or buffered hydrofluoric acid are used to etch the silicon nitride layer 8 and the silicon dioxide layer 7 on the front and back sides of the SOI silicon wafer A respectively to etch a plurality of holes as deep as the upper silicon layer 4 and the lower silicon layer 5. hole;

The fifth step is to deeply etch the exposed upper silicon layer 4 and lower silicon layer 5 by using deep reactive ion etching, or potassium hydroxide, or tetramethylammonium hydroxide, or ethylenediamine phosphoquinone To the buried oxide layer 6, the base 11, the coupling frame 12, the quality block 13, and the fixed block 14 are formed on the upper half;

Step 6, using buffered hydrofluoric acid to remove the exposed buried oxide layer 6;

The seventh step is to use deep reactive ion etching, or potassium hydroxide, or tetramethyl ammonium hydroxide, or ethylenediamine phosphoquinone to further etch the front side of the SOI silicon wafer A until the lower silicon layer 5 is etched. A certain depth in the center forms a support beam 15;

The eighth step is to perform high-temperature oxidation treatment on the front and back surfaces of the SOI silicon wafer B, and form a layer of silicon dioxide layer 7 on the front and back surfaces respectively; or deposit silicon dioxide on the front and back surfaces by chemical vapor deposition (CVD). Build up a silicon dioxide layer 7;

Step 9: Coating photoresist on the front side of the SOI silicon wafer B, exposing it according to a specific pattern, and developing it with a developer. This way the exposed pattern will appear. Then use reactive ion dry etching or buffered hydrofluoric acid to etch a plurality of holes deep to the upper silicon layer 4 on the silicon dioxide layer 7 on the front side of the SOI silicon wafer B;

In the tenth step, a silicon nitride layer 8 is deposited on the front and back sides of the SOI silicon wafer B by chemical vapor deposition;

In the eleventh step, a photoresist is coated on the back of the SOI silicon wafer B, and then exposed according to a specific pattern, and developed with a developer. This way the exposed pattern will appear. Reactive ion dry etching or buffered hydrofluoric acid are used to etch the silicon nitride layer 8 and the silicon dioxide layer 7 on the back side of the SOI silicon wafer B to respectively etch a plurality of holes as deep as the lower silicon layer 5;

In the twelfth step, the exposed lower silicon layer 5 is etched to the buried oxide layer 6 by using deep reactive ion etching, or potassium hydroxide, or tetramethylammonium hydroxide, or ethylenediamine phosphoquinone, The base 11, the coupling frame 12, the mass block 13, and the fixed block 14 forming the lower half;

In the thirteenth step, the exposed buried oxide layer 6 in the lower silicon layer 5 is removed by reactive ion dry etching or buffered hydrofluoric acid;

In the fourteenth step, the silicon dioxide layer 7 and the silicon nitride layer 8 on the back of the SOI silicon wafer A and the SOI silicon wafer B are removed;

In the fifteenth step, perform back-to-back silicon-silicon bonding on the SOI silicon wafer A and the SOI silicon wafer B to form a complete base 11, coupling frame 12, mass block 13, and fixed block 14;

In the sixteenth step, the silicon nitride layer on the front side of the bonded silicon wafer is removed by reactive ion dry etching;

In the seventeenth step, use deep reactive ion etching to deeply etch the exposed silicon layer on the front side of the bonded silicon wafer until the exposed silicon layer is cut through to form a free-moving elastic Beam 16, resonant beam 18, first comb-shaped coupling structure 17, second comb-shaped coupling structure 19, and gaps between mass block 13, fixed block 14, and base 11;

In the eighteenth step, the silicon dioxide layer 7 on the front side of the bonded silicon wafer is removed by reactive ion dry etching or buffered hydrofluoric acid;

In the nineteenth step, bond the front side of the bonded silicon wafer to the upper cover;

In the twentieth step, the silicon nitride layer on the back side of the bonded silicon wafer is removed by reactive ion dry etching;

The twenty-first step is to use deep reactive ion etching to etch the exposed part of the silicon layer on the back of the bonded silicon wafer until the exposed part of the silicon layer is cut through to form a freely movable The elastic beam 16, the resonant beam 18, the first comb-shaped coupling structure 17, the second comb-shaped coupling structure 19 and the gap between the mass block 13, the fixed block 14 and the base 11, thereby releasing the coupling frame 12 and the mass block 13, Form a freely movable support beam 15;

The twenty-second step, using reactive ion dry etching or buffered hydrofluoric acid to remove the silicon dioxide layer 7 on the back of the bonded silicon wafer;

The twenty-third step is to bond the back of the bonded silicon wafer with the lower cover to form a complete gyroscope;

The processing technology of the upper cover plate 2 and the lower cover plate 3 also includes:

A. Coating photoresist on the bonding surface of the upper cover 2 and the lower cover 3, then exposing it according to a specific pattern, and developing it with a developer. This way the exposed pattern will appear. Then use deep reactive ion etching, or potassium hydroxide, or tetramethyl ammonium hydroxide, or ethylenediamine phosphoquinone to etch the exposed parts of the upper cover plate 2 and the lower cover plate 3 to a certain depth. Location. Thus, a recessed area is formed on the bonding surfaces of the upper cover 2 and the lower cover 3 respectively, and the photoresist is removed.

B. Deposit metal at specified positions on the upper cover plate 2 and the lower cover plate 3, and etch the electrodes;

C. Before bonding with the SOI silicon wafer, the upper cover silicon wafer 2 and the lower cover silicon wafer 3 are cleaned;

Wherein, the silicon nitride layer 9 and the silicon dioxide layer 8 in the above processing technology in the present invention protect the silicon layer covered by them from being etched or corroded.

The deep etching and the etching method described in the present invention are one or more methods in the following methods: dry etching or wet etching, and the dry etching includes: deep reaction of silicon Ion etching and reactive ion etching.

Referring to Fig. 1 to Fig. 6, used material, equipment, technology in the above-mentioned method among the present invention all adopt prior art, but by utilizing these materials and the manufactured gyroscope of technology, have following advantage: the detection of this gyroscope The result is a frequency signal that can be easily interfaced with other signal processors, eliminating the need for signal processing steps such as analog-to-digital conversion. In addition, the structure of setting two groups of resonant beams 18 up and down in the vertical direction is to output the frequency change in the form of difference, and such output signal is more accurate, because the manufacturing method of the two groups of resonant beams 18 is the same, the materials are the same and the positions are basically the same , so when affected by temperature, the common mode errors generated by the two sets of resonant beams 18 are also basically the same, and the influence of temperature on the detection accuracy of the gyroscope can be eliminated through the differential output. The mass block obtained by bonding in the present invention is also relatively large, and there is a large resonance displacement in both the driving direction and the detection direction during the detection process, and the detection sensitivity is also improved. Moreover, the gyroscope is also provided with a feedback circuit in the detection direction. After the integrated circuit calculates the displacement of the mass block 13 from the signal detected by the second comb-shaped coupling structure 19 on the resonant beam, the feedback control system will send a feedback signal to the mass block. A feedback voltage is applied to maintain the mass 13 in an equilibrium position. The feedback control system can effectively enhance the stability of the system, reduce the nonlinearity of the system, widen the bandwidth of the system, and shorten the reaction time, thereby making the detection more accurate.

Claims (18)

1. a MEMS high precision resonance beam closed-loop control gyroscope, comprising: measure body, upper cover plate and lower cover, it is characterized in that, described measurement body comprises pedestal, coupling frame, the mass be connected with coupling frame and the fixed block being positioned at described mass center; Described pedestal and described fixed block and described upper cover plate and described lower cover are fixedly connected; Described mass is connected by multiple elastic beam with described coupling frame; The first pectination coupled structure is provided with between described mass and described fixed block; The side of described coupling frame is provided with brace summer; Described coupling frame is connected with described pedestal by described brace summer; Top and the bottom of the sidewall of described coupling frame are respectively arranged with resonance beam, and described resonance beam one end is connected with described coupling frame, and the other end is connected with pedestal respectively; The second pectination coupled structure is also provided with between described resonance beam and described pedestal; Described resonance beam and described second pectination coupled structure are for detecting rotational angular velocity.

2. MEMS high precision resonance beam closed-loop control gyroscope as claimed in claim 1, it is characterized in that, described brace summer and described resonance beam are elastic beam.

3. MEMS high precision resonance beam closed-loop control gyroscope as claimed in claim 1, is characterized in that, the square body of hollow out centered by described mass.

4. MEMS high precision resonance beam closed-loop control gyroscope as claimed in claim 1, it is characterized in that, described elastic beam is U-shaped elastic beam.

5. MEMS high precision resonance beam closed-loop control gyroscope as claimed in claim 3, is characterized in that, described elastic beam is arranged on four end angle places of described mass.

6. MEMS high precision resonance beam closed-loop control gyroscope as claimed in claim 1, it is characterized in that, described first pectination coupled structure is arranged in the clearance space between described mass and described fixed block.

7. MEMS high precision resonance beam closed-loop control gyroscope as claimed in claim 1, is characterized in that, described mass, described upper cover plate, described lower cover, described first pectination coupled structure and described second coupled structure are provided with electrode.

8. MEMS high precision resonance beam closed-loop control gyroscope as claimed in claim 1, it is characterized in that, described resonance beam and described brace summer are arranged on the same side of the described frame that is coupled.

9. MEMS high precision resonance beam closed-loop control gyroscope as claimed in claim 1, it is characterized in that, described pedestal is provided with groove, and described resonance beam is positioned at described groove.

10. MEMS high precision resonance beam closed-loop control gyroscope as claimed in claim 1, it is characterized in that, described resonance beam is upper and lower two groups, often organizes described resonance beam and comprises two resonance beam, is provided with two to described second pectination coupled structure described in every root between resonance beam and described pedestal; Described in a pair, the second pectination coupled structure is for driving described resonance beam, and another is to for detecting angular velocity of rotation.

11. MEMS high precision resonance beam closed-loop control gyroscopes as claimed in claim 10, it is characterized in that, described second pectination coupled structure comprises two comb matched, and one of them comb is connected with described resonance beam, and comb described in another is connected with described pedestal.

12. MEMS high precision resonance beam closed-loop control gyroscopes as claimed in claim 1, is characterized in that, described measurement body adopts the silicon bi-layer structure including upper silicon layer and lower silicon layer, is respectively arranged with buried oxide between every layer of silicon layer.

13. MEMS high precision resonance beam closed-loop control gyroscopes as claimed in claim 12, it is characterized in that, described resonance beam and described elastic beam take shape in described upper silicon layer.

14. 1 kinds of gyrostatic manufacturing process, is characterized in that, described manufacturing process comprises the following steps:

The first step, by high-temperature oxydation or deposition process, first piece of silicon on insulator front side of silicon wafer and the back side forms layer of silicon dioxide layer respectively;

Second step, by photoetching and etching, the silicon dioxide layer of first piece of silicon on insulator front side of silicon wafer will etch multiple hole being deep to upper silicon layer;

3rd step, deposit one deck silicon nitride layer on first piece of silicon on insulator front side of silicon wafer and the back side;

4th step, by photoetching and etching, removes the silicon nitride layer on the position in first piece of silicon on insulator front side of silicon wafer corresponding to brace summer and silicon dioxide layer respectively, and described upper silicon layer is etched to described buried oxide; Silicon nitride layer on position corresponding to first piece of silicon on insulator silicon chip back side Elastic beam, resonance beam and the gap between fixed block and mass and silicon dioxide layer are removed simultaneously, and described lower silicon layer is etched to described buried oxide, form half of pedestal, coupling frame, mass and fixed block;

5th step, by etching, removes described buried oxide, forms one deck elastic beam and resonance beam;

6th step, is etched to certain depth further to the position in first piece of silicon on insulator front side of silicon wafer corresponding to brace summer, forms brace summer;

7th step, by high-temperature oxydation or deposition process, second piece of silicon on insulator front side of silicon wafer and the back side forms layer of silicon dioxide layer respectively;

8th step, by photoetching and etching, the silicon dioxide layer of second piece of silicon on insulator front side of silicon wafer will etch multiple hole being deep to upper silicon layer;

9th step, at second piece of silicon on insulator front side of silicon wafer and back side deposit one deck silicon nitride;

Tenth step, by photoetching and etching, silicon nitride layer on position in second piece of silicon on insulator silicon chip back side corresponding to brace summer, elastic beam, resonance beam and the gap between fixed block and mass and silicon dioxide layer are removed, and described lower silicon layer is etched to described buried oxide, form half of pedestal, coupling frame, mass and fixed block;

11 step, by etching, removes described buried oxide, forms one deck elastic beam and resonance beam;

12 step, removes the silicon nitride layer of first piece and second piece silicon on insulator silicon chip back side and silicon dioxide layer respectively;

13 step, carries out back-to-back silicon-silicon bond conjunction by first piece and second piece of silicon on insulator silicon chip, forms complete pedestal, fixed block, mass and coupling frame;

14 step, removes the silicon nitride layer of key and rear front side of silicon wafer;

15 step, carrying out deep etching to key and rear front side of silicon wafer being exposed to outer upper silicon layer, forming through hole, thus forming freely movable upper strata elastic beam, upper strata resonance beam, upper strata first pectination coupled structure and upper strata second pectination coupled structure;

16 step, removes the silicon dioxide layer of key and rear front side of silicon wafer;

17 step, carries out bonding by key and rear front side of silicon wafer and upper cover plate;

18 step, removes the silicon nitride layer of key and rear silicon chip back side;

19 step, carrying out deep etching to key and rear silicon chip back side being exposed to outer upper silicon layer, forming through hole, thus forming freely movable brace summer, lower floor's elastic beam, lower floor's resonance beam, lower floor first pectination coupled structure and lower floor second pectination coupled structure;

20 step, removes the silicon dioxide layer of key and rear silicon chip back side;

21 step, carries out bonding by key and rear silicon chip back side and lower cover; Form complete gyroscope.

15. gyrostatic manufacturing process as claimed in claim 14, is characterized in that, also comprise the processing technology of described upper cover plate silicon chip and lower cover silicon chip:

A, on the bonding face of described upper cover plate and described lower cover respectively by photoetching, deep etching and etch each self-forming depressed area;

B, on described upper cover plate and described lower cover depositing metal, and etch electrode;

C, with described silicon on insulator wafer bonding before, described upper cover plate silicon chip and described lower cover silicon chip are cleaned.

16. gyrostatic manufacturing process according to claims 14 or 15, it is characterized in that, the method of described deep etching and described etching is one or more methods in following methods: dry etching or wet etching, and described dry etching comprises: the deep reaction ion etching of silicon and reactive ion etching.

17. gyrostatic manufacturing process according to claims 14 or 15, it is characterized in that, the described mordant for etching silicon layer is one or more the combination in following mordant: the xenon difluoride of potassium hydroxide, tetramethyl aqua ammonia, ethylenediamine phosphorus benzenediol or gaseous state.

18. gyrostatic manufacturing process according to claims 14 or 15, it is characterized in that, the described mordant for corrode silicon dioxide layer is one or more the combination in following mordant: the hydrogen fluoride of buffered hydrofluoric acid, 49% hydrofluorite or gaseous state.