CN210690623U

CN210690623U - MEMS device backstop structure that shocks resistance

Info

Publication number: CN210690623U
Application number: CN201921961344.3U
Authority: CN
Inventors: 凤瑞; 周铭; 商兴莲; 蒋鹏; 黄艳辉; 鞠莉娜
Original assignee: China North Industries Group Corp No 214 Research Institute Suzhou R&D Center
Current assignee: China North Industries Group Corp No 214 Research Institute Suzhou R&D Center
Priority date: 2019-11-14
Filing date: 2019-11-14
Publication date: 2020-06-05
Anticipated expiration: 2029-11-14

Abstract

The utility model discloses an anti-impact stop structure of an MEMS device, which comprises a mass block connected to an anchor point structure through a beam structure; the mass block and the beam structure are suspended on the detection electrode by the anchor point structure; a stop bump structure which is higher than the detection electrode in height and faces the mass block is arranged on the periphery of the detection electrode; and an elastic contact structure is arranged on the mass block towards the stop bump structure. When strong impact or vibration is input from the outside in the vertical direction, the mass block moves in the vertical direction under the action of inertia force, and when the impact or vibration causes the mass block to move to a design limit value, the elastic contact structure processed on the mass block collides and contacts with the stop bumps at the corresponding positions of the substrate layer or the cover cap. The elastic contact structure on the mass block deforms along the vertical direction after collision contact, so that impact energy is buffered and absorbed, the phenomenon of stress concentration generated on a contact point or a contact surface of the stop structure due to collision with the mass block is avoided, and the possibility of generation of breakage or fracture is reduced.

Description

MEMS device backstop structure that shocks resistance

Technical Field

The utility model relates to an electron field, concretely relates to vertical direction of MEMS device shocks resistance and transships elasticity backstop structure.

Background

MEMS sensors achieve the corresponding measurement to be measured by measuring some change in a tiny sensitive structure. The MEMS (micro Electro Mechanical System) sensor has the advantages of small volume, light weight, low power consumption, low cost and the like.

The MEMS inertial sensor comprises an MEMS acceleration sensor for detecting acceleration and an MEMS gyroscope for detecting angular velocity, and can be widely applied to the military and civil fields. In the field of industrial automation, it is mainly applied to advanced automatic safety systems, high-performance navigation systems, navigation stability, detection and prevention of rollover, and airbag and brake systems. In the field of consumer electronics, the method is mainly applied to digital products such as mobile phones and tablet computers, image stabilization and virtual reality products in photographic equipment, and computer games. In military application, the method is mainly applied to inertial guidance of ammunition, navigation and attitude control of an aircraft, stable platform, portable individual navigation and the like.

In some application occasions with strong impact and vibration, the MEMS inertial sensor needs to have corresponding impact resistance capability to ensure that the device does not lose efficacy or degrade performance, and acceleration or angular velocity measurement in severe environment is realized.

In actual circumstances, the external shock or vibration may be in any direction. The MEMS device is mostly a flat structure, and thus, according to the structural characteristics of the MEMS device, an external impact can be decomposed into an impact in a horizontal plane (XY plane) and an impact in a vertical direction (Z axis).

In order to solve the problem that the MEMS device fails due to large impact or strong vibration in a horizontal plane, the main solving method in the prior art is as follows:

the present invention relates to a microelectromechanical system device, a deceleration stop, a method for reducing shock, and a gyroscope, and to a european patent application EP2146182a1, a multisttage pro-mass removal with a mass mems structure. The deceleration beam and the deceleration groove are constructed into a deceleration structure, so that the gyro comb tooth structure can be decelerated or stopped before collision occurs under an impact condition.

U.S. Pat. No. 3, 6065341 [ Semiconductor Physical Quantity Sensor WithStopper Port ], U.S. Pat. No. 3, 4882933 [ Accelerometer with integrated cubic detection and control of visual data ], U.S. Pat. No. 3, 5721377 [ open vector Sensor with build-in Limit stops ], and Chinese Utility model Patent application [ a highly overload resistant MEMS gyroscope ], etc. propose impact-resistant overload micro-stop structures of different structural forms. These micro-stop structures solve the problem of MEMS device failure due to large impact in the horizontal plane.

In order to solve the problem that the MEMS device fails due to large impact in the vertical direction, the main solving method in the prior art is as follows:

the utility model discloses a patent application "a take capacitanc acceleration sensor in acoustics chamber" provides and designs the back plate that processes out to have damping hole and spacing bump at the back of the sensitive structure of acceleration sensor. The damping of the system is adjusted by comprehensively utilizing the damping holes in the back plate, and the limit salient points are utilized to prevent adhesion during overload, so that the strong impact resistance of the capacitive acceleration sensor is improved.

U.S. Pat. No. 3, 8596123, 2 MEMS Device with an arrangement Structure for enhanced Resistance stipulation proposes a T-shaped vertical stop Structure to achieve the purpose of limiting the vertical movement displacement of the mass block. Vertical stops of different configurations are proposed in U.S. Pat. No. 3, 5111693 for Motion detectors for micro mechanical Devices, U.S. Pat. No. 3, 5721377 for Angular positioning sensors with built-in limit stops, etc. However, the vertical stopping structures proposed in these patents are all fixed stopping structures that are not easily deformed. When the MEMS movable structure collides with the vertical stop structure under the action of strong impact or vibration, the fixed stop is not easy to deform due to high rigidity, and is not beneficial to buffering and absorbing the inertia force generated by impact, so that the contact part of the movable structure and the stop has high stress, and the movable structure is easy to break, fracture and the like.

SUMMERY OF THE UTILITY MODEL

In order to solve the problems existing in the prior art, the patent provides a vertical direction impact-resistant overload stop structure of an MEMS device.

The MEMS device is exemplified by a capacitive MEMS inertial sensor. The capacitive MEMS inertial sensor senses acceleration or angular velocity of external input through an internal movable sensing mass. Since the mass needs to move freely along a specific axis, the mass is generally connected to an anchor point structure through a beam structure, and the anchor point structure is fixed on the substrate of the sensor. When external input acceleration or angular velocity exists, the mass block shifts or moves along a specific axial direction, the displacement can be detected by means of capacitance change, and the input acceleration and the angular velocity are measured.

When the outside has large impact or strong vibration, the mass block deflects or deflects under the impact action, so that the mass block collides with the corresponding detection electrode. In order to avoid the situation that the structure fails due to collision or the beam structure is broken due to large-amplitude deformation under the condition of large impact or strong vibration, the displacement or deflection angle of the mass block under the condition of large impact or strong vibration needs to be limited.

The displacement or deflection limit of the mass in the horizontal plane is generally designed by using a stop structure in the horizontal plane. The displacement or deflection limitation of the mass in the vertical direction is generally designed by using a stop structure in the vertical direction below the mass. Because the current mainstream MEMS process is a typical plane processing process, the stop structure in the vertical direction is generally a fixed stop structure, and the elastic stop structure in the vertical direction is difficult to process under the condition of not obviously increasing the process complexity and the number of layers of the MEMS structure.

In order to solve the technical problem, the utility model discloses a technical scheme as follows:

the utility model provides a MEMS device backstop structure that shocks resistance, includes the quality piece that is connected to on the anchor point structure through the roof beam structure, and the anchor point structure suspends quality piece and roof beam structure on detecting electrode, sets up the backstop bump structure that highly is higher than detecting electrode and towards the quality piece at detecting electrode periphery, sets up the elastic contact structure towards the position of backstop bump structure on the quality piece.

Further, the elastic contact structure comprises a stop contact surface capable of being in contact with the stop bump structure and a plurality of elastic beams for supporting the stop contact surface on the mass block.

Further, the elastic beams are distributed around the stop contact surface in an axial symmetry or a central symmetry.

Further, the stop bump structure is arranged on the substrate layer and/or the cap.

Furthermore, the elastic contact structure and the mass block are processed and molded by the same process.

Furthermore, the elastic contact structure and the mass block are processed and molded simultaneously by the same process.

Furthermore, the corresponding stop bump structures on the substrate layer and/or the cap are processed and molded by the same process as the substrate layer and/or the cap.

The utility model discloses the beneficial effect who reaches:

this patent proposes a vertical direction of MEMS device elasticity backstop structure of transshipping shocks resistance. An elastic contact structure is designed and processed on the mass block, and corresponding stop bump structures are processed on the substrate layer and/or the cover cap of the MEMS device. When strong impact or vibration is input from the outside in the vertical direction, the mass block moves in the vertical direction under the action of inertia force, and when the impact or vibration causes the motion of the mass block to reach a design limit value, the elastic contact structure processed on the mass block collides and contacts with the stop bumps at the corresponding positions of the substrate layer or the cap. The elastic contact structure on the mass block deforms along the vertical direction after collision contact, so that impact energy is buffered and absorbed, the phenomenon of stress concentration generated on a contact point or a contact surface of the stop structure due to collision with the mass block is avoided, and the possibility of generation of breakage or fracture is reduced.

The elastic contact structure designed and processed on the mass block mainly comprises a buffer elastic beam and a stop contact surface. The designed buffer elastic beam and the stop contact surface are processed by the same process as the mass block of the MEMS device and are simultaneously processed and molded. The corresponding stop bump structures on the substrate layer and the cap are processed by the same process as the substrate and the cap, and only one etching step is needed. The vertical impact-resistant overload-resistant elastic stopping structure does not remarkably increase the processing technology of the MEMS device, and is easy to process and realize.

The elastic contact structure and the corresponding bump structure can be optimized through simulation design, so that the elastic buffering and stopping effect of the vertical direction on the mass block can be achieved under the condition of strong impact or vibration, and the phenomenon of adhesion between the bump structure and the stop contact surface can be avoided.

Drawings

FIG. 1 is a schematic horizontal plane diagram (area symmetry, mass asymmetry) of a sensitive structure layer of a MEMS accelerometer.

FIG. 2 is a schematic vertical section of a MEMS accelerometer.

Fig. 3 is a schematic horizontal plane diagram (area asymmetry) of a sensitive structure layer of the MEMS accelerometer.

FIG. 4 is a schematic diagram of a bump stop structure of a MEMS accelerometer.

FIG. 5 is a schematic horizontal plane view of a structural layer of a Z-axis impact resistant MEMS accelerometer.

Fig. 6 is a schematic diagram of an elastic contact structure.

Fig. 7 is a schematic view of a diagonal beam-type resilient contact structure.

Fig. 8 is a schematic view of an L-shaped beam elastic contact structure.

FIG. 9 is a schematic horizontal view of a structural layer of a Z-axis impact resistant MEMS accelerometer with multiple elastic contact structures.

Detailed Description

The present invention will be further described with reference to the accompanying drawings. The following examples are only for illustrating the technical solutions of the present invention more clearly, and the protection scope of the present invention is not limited thereby.

Taking a Z-axis capacitive MEMS accelerometer as an example, a schematic horizontal plane view of a sensitive structure layer of the Z-axis capacitive MEMS accelerometer is shown in fig. 1, and a schematic vertical section view of the Z-axis capacitive MEMS accelerometer is shown in fig. 2.

The accelerometer mass 101 is connected to an anchor point structure 103 by a beam structure 102. The anchor point structures 103 suspend the mass 101 and beam structures 102 above the detection electrodes 106. Etching away part of the mass 110 on the proof-mass 101 is designed such that the mass 101 is not equal on both sides of the axis around the beam structure 102. When the Z-axis acceleration is input from the outside, the unequal masses on the two sides generate a torsional moment around the axis of the beam structure 102, the mass block 101 deflects around the beam structure 102 under the action of the Z-axis acceleration, and the deflection angles are detected by the

detection electrodes

106a and 106b arranged on the two sides below the mass block, so that the Z-axis input acceleration can be calculated.

The asymmetric mass of the proof-mass 101 with respect to the beam structure 102 can also be achieved by arranging the beam structure 102 at a position offset from the symmetry axis of the proof-mass 101, as shown in fig. 3.

When there is strong Z-axis shock or vibration, the mass 101 may collide strongly with the detection electrode 106 under the shock or vibration. The intense impact may cause the impact contact to break or fracture. To avoid this, a common design method is to design and machine stop

bump structures

201a and 201b under the proof mass higher than the detection electrode 106, as shown in fig. 4. However, since the bump stop structure and the mass block 101 in contact with the bump stop structure are both rigid structures and are not easy to deform, the bump stop structure is easy to damage or break after colliding with the lower bottom surface of the mass block under a strong impact condition.

For the anti strong impact of Z axle or the inefficacy that the vibration produced of improving the device, avoid the strong impact of Z axle or vibration, this patent has designed a vertical direction backstop structure that shocks resistance. The

elastic contact structures

202a and 202b are designed to be machined on the mass 101, as shown in fig. 5, and each of the

elastic contact structures

202a and 202b is composed of a buffer elastic beam structure 301 and a stop contact surface structure 302, as shown in fig. 6. The

elastic contact structures

202a, 202b are located in the mass 101 above the

stop bump structures

201a, 201 b. When strong Z-axis impact or strong vibration exists, the mass block 101 deflects under the impact or vibration, and the

stop bump structures

201a and 201b are in collision contact with the stop contact surface structures 302 in the

elastic contact structures

202a and 202b respectively. Because the buffering elastic beam structure 301 is easy to deform, the movement distance of the elastic contact structure 202 after being contacted with the

stop bump structures

201a and 201b can be increased, the contact action time is prolonged, and the buffering release of collision contact acting force and energy is realized.

Through simulation optimization design, the buffer elastic beam structure 301 can be designed according to the requirements of impact resistance and vibration, so that the deformation displacement of the buffer elastic beam structure after collision is in a reasonable range. The reasonable deformation range is to ensure that the structure is not damaged or broken after collision and ensure that the mass block is not contacted with the detection electrode due to the fact that deformation displacement is not too large.

The cushioned spring beam structure 301 of the spring contact structure may also be designed in a diagonally fixed beam structure as shown in fig. 7 or in an L-shaped beam structure as shown in fig. 8, as desired.

The arrangement position of the elastic contact structure in the mass 101 can be designed into a plurality of positions as required, as shown in fig. 9.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, a plurality of modifications and variations can be made without departing from the technical principle of the present invention, and these modifications and variations should also be considered as the protection scope of the present invention.

Claims

1. An anti-impact stop structure of an MEMS device is characterized by comprising a mass block connected to an anchor point structure through a beam structure; the mass block and the beam structure are suspended on the detection electrode by the anchor point structure; a stop bump structure which is higher than the detection electrode in height and faces the mass block is arranged on the periphery of the detection electrode; and an elastic contact structure is arranged on the mass block towards the stop bump structure.

2. A MEMS device impact-resistant stop structure as claimed in claim 1 wherein said resilient contact structure comprises a stop contact surface contactable with said stop bump structure and a plurality of resilient beams supporting said stop contact surface on said mass.

3. An impact-resistant stop structure for a MEMS device as claimed in claim 2 wherein the plurality of spring beams are disposed in axial or central symmetry about the stop interface.

4. A MEMS device impact-resistant stop structure as claimed in claim 1 wherein the stop bump structure is provided on the substrate layer and/or the cap.

5. The MEMS device impact-resistant stop structure of claim 1 wherein the resilient contact structure and the mass are formed by the same process.

6. The MEMS device impact-resistant stop structure of claim 1 wherein the spring contact structure and the mass are formed simultaneously using the same process.

7. An impact-resistant stop structure for a MEMS device as claimed in claim 4, wherein the corresponding bump stop structures on the substrate layer and/or cap are formed by the same process as the substrate layer and/or cap.