CN218099225U - Sawtooth structure MEMS accelerometer with adjustable comb tooth overlapping length - Google Patents
Sawtooth structure MEMS accelerometer with adjustable comb tooth overlapping length Download PDFInfo
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- CN218099225U CN218099225U CN202222258592.XU CN202222258592U CN218099225U CN 218099225 U CN218099225 U CN 218099225U CN 202222258592 U CN202222258592 U CN 202222258592U CN 218099225 U CN218099225 U CN 218099225U
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Abstract
The utility model discloses a zigzag structure MEMS accelerometer with adjustable comb teeth overlapping length, which comprises a substrate layer, wherein a structural layer is arranged on the substrate layer, a movable mass block is arranged on the structural layer, and a positive closed-loop feedback unit and a negative closed-loop feedback unit are symmetrically arranged in the middle of the movable mass block; the upper end and the lower end of the movable mass block are respectively provided with a positive sensitive unit and a negative sensitive unit, and the sensitive units are provided with comb tooth overlapping length adjusting devices. The invention increases the characteristic size of the comb tooth gap of the structural layer, reduces the process requirement, and improves the process friendliness and realizability; and through the comb overlapping length adjusting device, the overlapping length between the comb teeth of the sensitive unit can be increased, the dead-against area of the comb teeth is increased, the gap between the comb teeth is reduced, the sensitivity and the resolution of a device are further improved, and the comprehensive precision of the MEMS accelerometer is optimized.
Description
Technical Field
The utility model relates to a MEMS accelerometer technical field, concretely relates to broach overlap length adjustable's sawtooth structure MEMS accelerometer.
Background
The MEMS accelerometer is an acceleration sensor manufactured by using a MEMS process, and is a device for detecting acceleration. MEMS accelerometer has advantages such as small, the integrated level is high, the precision is high, is used in more and more fields, especially fields such as inertial navigation, unmanned aerial vehicle, industrial robot. Among the MEMS accelerometers, a capacitive MEMS accelerometer is one of the most widely used MEMS accelerometers. Acceleration of effect on the quality piece can make the broach that links to each other with the quality piece take place the displacement, then can change the capacitance value between the broach pair, detects the size of acceleration value through the change that detects capacitance value.
The sensitivity, resolution and other key indexes of the capacitive MEMS accelerometer are determined by comb teeth to gaps, the comb teeth to gaps are completely dependent on the level of process level of a tape production factory, especially an etching process for determining the size of the comb teeth gaps can achieve high depth-to-width ratio, small comb teeth gaps and high consistency in the tape production factory, more importantly, the cost of mature process tape production with high processing precision is high, the tape production period is long, and most of the existing processes are abroad, which seriously restricts the development and application of domestic high-sensitivity and high-resolution MEMS accelerometers.
In the prior art, patent No. CN114088976: the MEMS accelerometer with the adjustable comb tooth gap changes the gap between the fixed detection comb tooth and the movable detection comb tooth by using electrostatic resultant force, so that the sensitivity of the accelerometer is improved, the zero offset is compensated, but the adjustment direction of the electrostatic force is the same as the sensitive direction of a device, and the difficulty and the accuracy of adjustment are increased.
SUMMERY OF THE UTILITY MODEL
To the above problem, the utility model provides a broach overlap length adjustable zigzag structure MEMS accelerometer, through the position of the fixed broach of adjustment zigzag, the overlap length of the fixed broach of increase zigzag and movable broach to improve MEMS accelerometer's sensitivity, and the fixed broach adjustment direction of zigzag is perpendicular with the sensitive direction of device, has reduced the degree of difficulty of adjusting.
The utility model adopts the following technical proposal:
a sawtooth structure MEMS accelerometer with adjustable comb tooth overlapping length is characterized by comprising a substrate layer, wherein a structural layer is arranged on the substrate layer, a movable mass block is arranged on the structural layer, and a positive closed-loop feedback unit and a negative closed-loop feedback unit are symmetrically arranged in the middle of the movable mass block; and the upper end and the lower end of the movable mass block are respectively provided with a positive sensitive unit and a negative sensitive unit.
The positive sensitive unit and the negative sensitive unit have the same structure and comprise comb tooth overlapping length adjusting devices, first fixed anchor points, sensitive electrodes, sawtooth-shaped fixed sensitive comb teeth and sawtooth-shaped movable sensitive comb teeth; the lower side of the sensitive electrode is provided with sawtooth-shaped fixed sensitive comb teeth; the sawtooth-shaped movable sensitive comb teeth are arranged on the movable mass block and are matched with the sawtooth-shaped fixed sensitive comb teeth; the overlapping length of the zigzag comb tooth pair can be flexibly adjusted through the comb tooth overlapping length adjusting device.
The comb tooth overlapping length adjusting device comprises a comb tooth overlapping length adjusting beam, an overlapping length adjusting force application comb tooth pair, a positive comb tooth overlapping length adjusting force application electrode and a negative comb tooth overlapping length adjusting force application electrode; the upper part of the comb tooth overlapping length adjusting beam is connected with a first fixed anchor point, and the lower part of the comb tooth overlapping length adjusting beam is connected with a sensitive electrode; the left end and the right end of the sensitive electrode are provided with an overlapping length adjusting force application comb tooth pair; and the upper end and the lower end of the overlapping length adjustment force application comb tooth pair are respectively connected with a positive comb tooth overlapping length adjustment force application electrode and a negative comb tooth overlapping length adjustment force application electrode. The voltage of the force application electrode is adjusted by adjusting the overlapping length of the positive comb teeth and the negative comb teeth, the comb tooth overlapping length adjusting beam is driven to move, the position of the sawtooth-shaped fixed sensitive comb teeth is adjusted, and the overlapping length of the sawtooth-shaped fixed sensitive comb teeth and the sawtooth-shaped movable sensitive comb teeth is increased. And due to the characteristics of the sawtooth-shaped comb teeth, the dead-against area between the sawtooth-shaped sensitive comb teeth is increased, the comb tooth gap is also reduced, and the sensitivity and the resolution of the accelerometer are further increased.
Furthermore, the positive closed-loop feedback unit and the negative closed-loop feedback unit have the same structure and respectively comprise a feedback electrode and a force feedback comb tooth pair arranged on the movable mass block, and a second fixed anchor point is arranged on the feedback electrode.
Furthermore, tooth tips of the sawtooth-shaped fixed sensitive comb teeth and the sawtooth-shaped movable sensitive comb teeth are in arc structures. On one hand, the edge effect of the charge is weakened, and the linearity of the device is enhanced; on the other hand, the stress generated by manufacturing is reduced, and the structural reliability is improved.
Furthermore, the left end and the right end of the movable mass block are connected and suspended on the base layer through elastic connecting devices.
Further, the material of the base layer is silicon.
Further, the base layer material is glass.
Further, the structural layer is made of silicon.
The beneficial effects of the utility model are that:
1. during initial design, the sawtooth-shaped fixed sensitive comb teeth and the sawtooth-shaped movable sensitive comb teeth are properly separated in the overlapping direction, so that the characteristic size of the comb tooth gap of the structural layer is increased, the process requirement is lowered, and the process friendliness and the realizability are improved;
2. through the comb overlapping length adjusting device, the overlapping length between the fixed sensitive comb teeth and the movable sensitive comb teeth can be increased, the dead-against area of the comb teeth is increased, the gap between the comb teeth is reduced, the sensitivity and the resolution of a device are further improved, and the comprehensive precision of the MEMS accelerometer is improved;
3. the invention adopts a differential detection and closed-loop control mode, and the device has small noise and good linearity;
4. the invention has simple structure, greatly reduces the requirement on the processing technology compared with the prior art, can realize mass production based on domestic technology, and has low cost and short processing period.
Drawings
To illustrate the technical solutions of the embodiments of the present invention more clearly, the drawings of the embodiments will be briefly described below, and it is obvious that the drawings in the following description only relate to some embodiments of the present invention, and are not intended to limit the present invention.
FIG. 1 is a schematic structural view of the present invention;
FIG. 2 is a schematic view showing a state where the comb overlapping length adjusting device of the present invention is not in operation;
FIG. 3 is a schematic view showing the state of zigzag comb teeth when the comb overlapping length adjusting device of the present invention is not in operation;
FIG. 4 is a schematic view showing the operation of the comb overlapping length adjusting device according to the present invention;
FIG. 5 is a schematic diagram showing the state of the sawtooth-shaped comb teeth when the comb overlapping length adjusting device of the present invention is in operation.
In the figure:
1-a substrate layer, 2-a structural layer, 3-a positive sensitive unit, 4-a negative sensitive unit, 5-a movable mass block, 6-a positive closed loop feedback unit, 7-a negative closed loop feedback unit, 8-a comb overlapping length adjusting device, 9-a first fixed anchor point, 10-a sensitive electrode, 11-a sawtooth fixed sensitive comb, 12-a sawtooth movable sensitive comb, 13-a comb overlapping length adjusting beam, 14-an overlapping length adjusting force applying comb pair, 15-a positive comb overlapping length adjusting force applying electrode, 16-a negative comb overlapping length adjusting force applying electrode, 17-an elastic connecting device, 18-a force feedback electrode, 19-a second fixed anchor point and 20-a force feedback comb pair.
Detailed Description
In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the drawings of the embodiments of the present invention are combined below to clearly and completely describe the technical solution of the embodiments of the present invention. Unless otherwise defined, technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this disclosure belongs. The use of the word "comprising" or "comprises", and the like, in this disclosure is intended to mean that the elements or items listed before that word, include the elements or items listed after that word, and their equivalents, without excluding other elements or items. "upper", "lower", "left", "right", and the like are used only to indicate relative positional relationships, and when the absolute position of the object being described is changed, the relative positional relationships may also be changed accordingly.
The present invention will be further described with reference to the accompanying drawings and examples.
As shown in fig. 1, the zigzag structure MEMS accelerometer with adjustable comb teeth overlapping length is characterized by comprising a substrate layer 1 made of silicon or glass, wherein the substrate layer 1 is provided with a structure layer 2 made of silicon, the structure layer 2 is provided with a movable mass block 5, and the middle of the movable mass block 5 is symmetrically provided with a positive closed-loop feedback unit 6 and a negative closed-loop feedback unit 7; the upper end and the lower end of the movable mass block 5 are respectively provided with a positive sensitive unit 3 and a negative sensitive unit 4.
The positive sensitive unit 3 and the negative sensitive unit 4 have the same structure and comprise a comb tooth overlapping length adjusting device 8, a first fixed anchor point 9, a sensitive electrode 10, a sawtooth-shaped fixed sensitive comb tooth 11 and a sawtooth-shaped movable sensitive comb tooth 12; the lower side of the sensitive electrode 10 is provided with a sawtooth-shaped fixed sensitive comb 11; the sawtooth-shaped movable sensitive comb teeth 12 are arranged on the movable mass block 5 and are matched with the sawtooth-shaped fixed sensitive comb teeth 11.
The comb overlapping length adjusting device 8 comprises a comb overlapping length adjusting beam 13, an overlapping length adjusting force application comb pair 14, a positive comb overlapping length adjusting force application electrode 15 and a negative comb overlapping length adjusting force application electrode 16; the upper part of the comb tooth overlapping length adjusting beam 13 is connected with a first fixed anchor point 9, and the lower part of the comb tooth overlapping length adjusting beam is connected with a sensitive electrode 10; the left end and the right end of the sensitive electrode 10 are provided with an overlapping length adjustment force application comb tooth pair 14; the upper and lower ends of the overlapping length adjustment force application comb tooth pair 14 are respectively connected with a positive comb tooth overlapping length adjustment force application electrode 15 and a negative comb tooth overlapping length adjustment force application electrode 16.
The positive closed-loop feedback unit 6 and the negative closed-loop feedback unit 7 have the same structure, and both comprise a feedback electrode 18 and a force feedback comb tooth pair 20 arranged on the movable mass block, and a second fixed anchor point 19 is arranged on the feedback electrode 18.
The tooth tips of the sawtooth-shaped fixed sensitive comb teeth 11 and the sawtooth-shaped movable sensitive comb teeth 12 are in arc structures, so that on one hand, the edge effect of charges is weakened, and the linearity of a device is enhanced; on the other hand, the stress generated by manufacturing is reduced, and the structural reliability is improved. The angle of the tooth top can be adjusted during design, so that the positive area and the negative area of the comb gap adjustment of the comb overlapping length adjusting device 8 can be changed.
The left and right ends of the movable mass 5 are connected and suspended on the base layer 1 through elastic connecting devices 17.
As shown in fig. 2 and 3, when the comb overlapping length adjusting device 8 is not in operation, the voltage of the positive comb overlapping length adjusting force application electrode 15 and the negative comb overlapping length adjusting force application electrode 16 is zero, when the MEMS accelerometer is subjected to an acceleration in the sensitive axial direction, the movable mass block 5 undergoes a small displacement under the action of an inertial force, i.e., deviates from a structural mechanical zero position, and at this time, the gap between the sawtooth-shaped fixed sensitive comb 11 and the sawtooth-shaped movable sensitive comb 12 of the positive sensitive unit 3 and the negative sensitive unit 4 changes, thereby causing a capacitance change between the sensitive electrodes, and a change value of the capacitance can be read out through the interface circuit, so as to obtain the magnitude of the acceleration, and the inertia force is balanced through the positive closed-loop feedback unit 6 and the negative closed-loop feedback unit 7, so that the movable mass block 5 is restored to the mechanical zero position, thereby achieving the closed-loop detection of the acceleration.
As shown in fig. 4, when the comb overlapping length adjusting device 8 works, in the positive sensitive unit 3 and the negative sensitive unit 4, the positive comb overlapping length adjusting force application electrode 15 and the negative comb overlapping length adjusting force application electrode 16 are arranged to adjust the voltage of the force application electrode, so that the comb overlapping length adjusting device 8 generates a proper electrostatic resultant force to drive the sensitive electrode 10 to generate a micro-displacement, and further the position of the fixed sensitive comb tooth 11 connected with the sensitive electrode 10 is changed slightly, thereby increasing the overlapping length of the fixed sensitive comb tooth 11 and the movable sensitive comb tooth 12. And benefiting from the characteristics of the sawtooth-shaped comb teeth, as shown in fig. 5, the dead-against area between the sawtooth-shaped sensitive comb teeth is increased, and meanwhile, the comb tooth gap is also reduced, so that the sensitivity and the resolution of the accelerometer are further increased.
The voltages applied to the positive comb-tooth overlapping length adjustment force-applying electrode 15 and the negative comb-tooth overlapping length adjustment force-applying electrode 16 are respectively V dc +V ac 、V dc -V ac The thickness of the force application comb tooth pair 14 is adjusted to h (the thickness of the structural layer) by the overlapping length, and the overlapping length is adjusted to l 0 And n pairs in total, the resultant electrostatic force F generated by the comb tooth overlapping length adjusting device 8 is as follows:
wherein epsilon is a vacuum dielectric constant and is dimensionless; n is 14 pairs of force application comb tooth pairs for adjusting the overlapping length, and the unit is a pair; h is the thickness (the thickness of the structural layer) of the force application comb tooth pair 14 adjusted by the overlapping length, and is mum; v dc 、V ac Is the voltage, V; l 0 The overlap length distance, μm, between the two comb teeth of the force application comb tooth pair 14 is adjusted for the overlap length.
At this time, the micro displacement Δ x generated by the comb teeth overlapping length adjusting beam 13 is adjusted by the MEMS accelerometer comb teeth overlapping length adjusting device 8:
in the formula, k is the rigidity of the comb tooth overlapping length adjusting beam, and is N/m.
The voltage of the force application electrode 15 and the voltage of the force application electrode 16 are adjusted by controlling the overlapping length of the positive comb teeth and the overlapping length of the negative comb teeth, and then the value of delta x is adjusted.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention in any way, and although the present invention has been disclosed with reference to the preferred embodiment, it is not intended to limit the present invention, and any person skilled in the art can make modifications or changes to equivalent embodiments with equivalent changes when using the technical contents disclosed above without departing from the technical scope of the present invention, but all the technical contents of the present invention do not depart from the technical scope of the present invention, and any simple modifications, equivalent changes and modifications made to the above embodiments by the technical matters of the present invention are all within the scope of the technical solution of the present invention.
Claims (7)
1. The sawtooth-shaped structure MEMS accelerometer with the adjustable comb tooth overlapping length is characterized by comprising a substrate layer (1), wherein a structure layer (2) is arranged on the substrate layer (1), a movable mass block (5) is arranged on the structure layer (2), and a positive closed-loop feedback unit (6) and a negative closed-loop feedback unit (7) are symmetrically arranged in the middle of the movable mass block (5); the upper end and the lower end of the movable mass block (5) are respectively provided with a positive sensitive unit (3) and a negative sensitive unit (4);
the positive sensitive unit (3) and the negative sensitive unit (4) have the same structure and comprise comb tooth overlapping length adjusting devices (8), first fixed anchor points (9), sensitive electrodes (10), sawtooth-shaped fixed sensitive comb teeth (11) and sawtooth-shaped movable sensitive comb teeth (12); the lower side of the sensitive electrode (10) is provided with a sawtooth-shaped fixed sensitive comb (11); the sawtooth-shaped movable sensitive comb teeth (12) are arranged on the movable mass block (5) and are matched with the sawtooth-shaped fixed sensitive comb teeth (11);
the comb overlapping length adjusting device (8) comprises a comb overlapping length adjusting beam (13), an overlapping length adjusting force application comb pair (14), a positive comb overlapping length adjusting force application electrode (15) and a negative comb overlapping length adjusting force application electrode (16); the upper part of the comb tooth overlapping length adjusting beam (13) is connected with a first fixed anchor point (9), and the lower part of the comb tooth overlapping length adjusting beam is connected with a sensitive electrode (10); the left end and the right end of the sensitive electrode (10) are provided with an overlapping length adjustment force application comb tooth pair (14); the upper end and the lower end of the overlapping length adjustment force application comb tooth pair (14) are respectively connected with a positive comb tooth overlapping length adjustment force application electrode (15) and a negative comb tooth overlapping length adjustment force application electrode (16).
2. The MEMS accelerometer with the sawtooth structure and the adjustable comb-tooth overlapping length according to claim 1, wherein the positive closed-loop feedback unit (6) and the negative closed-loop feedback unit (7) have the same structure, and each of the positive closed-loop feedback unit and the negative closed-loop feedback unit comprises a feedback electrode (18) and a force feedback comb-tooth pair (20) arranged on the movable mass block, and a second fixed anchor point (19) is arranged on the feedback electrode (18).
3. The MEMS accelerometer with the sawtooth-shaped structure and the adjustable overlapping length of the comb teeth as claimed in claim 1, wherein the tooth tips of the sawtooth-shaped fixed sensitive comb teeth (11) and the sawtooth-shaped movable sensitive comb teeth (12) are in a circular arc structure.
4. A comb-teeth overlapping length adjustable saw-tooth structure MEMS accelerometer according to claim 1, characterized in that the movable mass (5) is connected and suspended at the left and right ends to the base layer (1) by elastic connecting means (17).
5. The MEMS accelerometer with comb teeth overlapping length adjustable structure according to claim 1, wherein the material of the substrate layer (1) is silicon.
6. The comb-teeth overlapping length adjustable sawtooth structure MEMS accelerometer according to claim 1, characterized in that the substrate layer (1) material is glass.
7. A comb-teeth overlapping length adjustable saw-tooth structure MEMS accelerometer according to claim 1, characterized in that the material of the structural layer (2) is silicon.
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| CN202222258592.XU CN218099225U (en) | 2022-08-26 | 2022-08-26 | Sawtooth structure MEMS accelerometer with adjustable comb tooth overlapping length |
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