CN112444238A

CN112444238A - Acceleration gyro sensor

Info

Publication number: CN112444238A
Application number: CN201910759974.0A
Authority: CN
Inventors: 陈朝喜
Original assignee: Beijing Xiaomi Mobile Software Co Ltd
Current assignee: Beijing Xiaomi Mobile Software Co Ltd
Priority date: 2019-08-16
Filing date: 2019-08-16
Publication date: 2021-03-05

Abstract

The acceleration gyro sensor comprises a Micro Electro Mechanical System (MEMS) chip and an Application Specific Integrated Circuit (ASIC) substrate, wherein a supporting body for supporting the MEMS chip is arranged on the ASIC substrate, part of the supporting body in the supporting body is fixedly connected with the MEMS chip, the other part of the supporting body is in lap joint with the MEMS chip, the position of the supporting body fixedly connected with the MEMS chip on the ASIC substrate is positioned in the position of the supporting body stressed in a preset range when the ASIC substrate is deformed under the action of external stress. According to the method and the device, the influence of external stress on the detection precision can be reduced, and the detection precision of the acceleration gyro sensor is improved.

Description

Acceleration gyro sensor

Technical Field

The present disclosure relates to the field of semiconductor technology, and in particular, to an acceleration gyro sensor.

Background

With the rapid development of scientific technology, intelligent portable electronic devices are becoming popular, such as smart phones, smart bracelets, smart edges, tablet computers, and the like. At present, more and more portable electronic devices are provided with an acceleration gyro sensor (a + g sensor) so that the portable electronic devices have a colorful user experience.

The a + g sensor is seriously influenced by stress and temperature rise, so that the a + g sensor has noises such as offset and temperature drift, and the noises can be superposed on the output of the a + g sensor to seriously influence the detection performance of the a + g sensor.

In the related art, the a + g sensor includes an Application Specific Integrated Circuit (ASIC) chip substrate and a Micro-Electro-Mechanical System (MEMS) pressure sensor chip. In the a + g sensor design manufacturing process, a high sensitivity of the a + g sensor is desirable to be able to detect very small signals, but since the a + g sensor inevitably introduces stress during the manufacturing and packaging processes, especially during the packaging process, any small stress changes may affect the detection accuracy of the sensor.

Therefore, it is imperative to provide an a + g sensor capable of reducing the influence of external stress such as package stress on the detection accuracy.

Disclosure of Invention

To overcome the problems in the related art, the present disclosure provides an acceleration gyro sensor.

According to the embodiment of the disclosure, an acceleration gyro sensor is provided, which comprises a Micro Electro Mechanical System (MEMS) chip and an Application Specific Integrated Circuit (ASIC) substrate, wherein a supporting body for supporting the MEMS chip is arranged on the ASIC substrate, part of the supporting body in the supporting body is fixedly connected with the MEMS chip, the other part of the supporting body is in lap joint with the MEMS chip, the position of the supporting body fixedly connected with the MEMS chip on the ASIC substrate is located in the position of the supporting body stressed by the MEMS chip in a preset range when the ASIC substrate is deformed under the action of external stress.

In one example, the number of the supporting bodies fixedly connected with the MEMS chip is one.

In another example, the number of supports that are lap-jointed to the MEMS chip is 0.

In a further example, the position of the support body fixedly connected with the MEMS chip on the ASIC substrate is a position where a distance between a set inductance and/or a set capacitance exceeds a set distance threshold.

In yet another example, a position of a support body fixedly connected with the MEMS chip on the ASIC substrate is located in a central region of the ASIC substrate.

In yet another example, the support body fixedly connected with the MEMS chip is fixed at the set position of the ASIC substrate by low stress glue or low stress solder.

In yet another example, the low stress glue is a silicon or silicone glue and the low stress solder is a lead tin solder.

In yet another example, the ASIC substrate is provided with a groove, and the support is embedded in the groove.

In yet another example, the support body is of unitary construction with the recess.

In another example, the support body fixedly connected to the MEMS chip is made of an elastic conductive material.

The technical scheme provided by the embodiment of the disclosure can have the following beneficial effects: the support body for supporting the MEMS chip is partially overlapped with the MEMS chip, so that the MEMS chip is not influenced by stress when the ASIC substrate is deformed under the action of external stress. And set up partial supporter and MEMS chip fixed connection, and with this supporter setting with MEMS chip fixed connection on ASIC basement be located when the ASIC basement receives external stress effect to take place deformation, the stress that the MEMS chip receives the supporter is in the position of predetermineeing the within range for when the ASIC basement receives external stress effect to take place deformation, can reduce the MEMS chip and receive the stress that comes from the supporter with MEMS chip fixed connection, further can reduce the influence of MEMS chip deformation to detection precision, improve the high detection precision of acceleration gyro sensor.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and together with the description, serve to explain the principles of the invention.

Fig. 1 is a schematic diagram of an a + g sensor structure with a comb-shaped capacitor according to an exemplary embodiment.

FIG. 2 is a schematic diagram illustrating a process for creating a differential capacitance after a fixed plate and two movable plates are partially enlarged, according to an exemplary embodiment.

FIG. 3 is a schematic diagram illustrating the generation of an initial static capacitance between a fixed plate and a movable plate when moving without an external force, according to an exemplary embodiment.

FIG. 4 is a schematic diagram illustrating the generation of a differential capacitance between a fixed plate and a movable plate according to an exemplary embodiment.

Fig. 5 is a schematic diagram illustrating the connection of an ASIC substrate and a MEMS chip when a large number of supports are included according to an exemplary embodiment.

Fig. 6 is a diagram illustrating a MEMS chip after being stressed by a support according to an exemplary embodiment.

Fig. 7 is a partially enlarged schematic view of an internal structure of an a + g sensor according to an exemplary embodiment.

Fig. 8 is a diagram illustrating another MEMS chip after being stressed by a support according to an exemplary embodiment.

Detailed description of the preferred embodiments

Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, like numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the invention, as detailed in the appended claims.

The A + g sensor provided by the present disclosure is a sensor with a comb-tooth structure capacitance. Fig. 1 is a schematic diagram of an internal structure of an a + g sensor according to an exemplary embodiment of the present disclosure. Referring to fig. 1, the a + g sensor has a plurality of capacitor plates formed by comb-shaped structures inside. The capacitor plate includes a fixed plate and a movable plate. The fixed polar plate is fixed on the ASIC substrate, and the movable polar plate is arranged in the MEMS chip. The movable polar plate is displaced under the action of external force to generate polar distance change, so that capacitance between the fixed polar plate and the movable polar plate is changed to form a differential capacitor. The differential capacitance has a functional relationship with the acceleration a or the angular velocity w. The acceleration a and the angular velocity w can be detected by using the functional relationship.

Fig. 2 is a schematic diagram of a process of generating a differential capacitor by partially enlarging one fixed plate and two movable plates in fig. 1. Referring to fig. 2, when the movable plate moves a distance Δ x, the distance between the movable plate and the fixed plate is changed from the original fixed distance x₀Change to x₀+. DELTA x, resulting in a differential capacitance Δ C. Wherein the capacitance between a movable plate and a fixed plate is represented by C₁Is changed into C_s0-. DELTA.C. The capacitance between the other movable plate and the fixed plate is represented by C₂Is changed into C_s0+△C。

The present disclosure will be described below with respect to the relationship between the acceleration a or the angular velocity w and the differential capacitance.

FIG. 3 shows an initial static capacitance C generated between the fixed plate and the movable plate when no external force is applied to move₀Schematic representation of (a). In fig. 3, the inherent distances between the movable plate and the two adjacent fixed plates are d, the relative area between the two adjacent fixed plates is a, and the initial static capacitance between the movable plate and the two adjacent fixed plates is C₀The dielectric constant between the fixed plate and the movable plate is epsilon. Wherein the capacitance between a fixed plate and a movable plate is C₁The capacitance between the other fixed plate and the movable plate is C₂. In the initial state (i.e. without external force), the capacitor C₁＝C₂＝C₀。

Fig. 4 shows a schematic diagram of the differential capacitance ac generated between the fixed and movable plates. In FIG. 4, when the movable plate is moved by an external force, the distance between the fixed plate and the movable plate changes, and the natural frequency of the movable plate is w₀The distance between the movable polar plate and the two adjacent polar plates is d₁And d₂The dielectric constant epsilon is not changed, and the relative area A between two adjacent fixed polar plates is also not changed. The capacitance C formed at this time₁And C₂And when they are not equal, they form a differential capacitor DeltaC. And (3) obtaining a formula (1) according to a transfer function deduced by the solid motion mechanical model.

When the movable plate is moved by an external force, the formula (3) and the formula (4) can be obtained according to the formula (2).

Equations (5) and (6) can be obtained using a taylor series expansion for equations (3) and (4):

in practical application, because the inherent distance d between the movable plate and the two adjacent fixed plates in the a + g sensor is micron-sized, and when the movable plate is moved under the action of an external force, the distance Δ d of the distance between the fixed plate and the movable plate is very small and is one hundredth, one thousandth or even lower than the micron-sized inherent distance d, the high-order powers in the formula (5) and the formula (6) can be ignored, and the formula (7) can be obtained after only one term is reserved.

In equation 7, the differential capacitance Δ C is equal to the static capacitance C₀Multiplied by the quotient of the varying distance ad and the intrinsic distance d of the movable plate to the adjacent fixed plate.

According to the vibration model of vibration mechanics, the relationship among the damping force, the elastic force, the driving force, and the acceleration to which it is subjected can be determined by, for example, equation (8):

after the formula (8) is subjected to pull-type transformation, the formula (9) can be obtained.

mS²Y(s)+cSY(s)+kY(s)＝mX(s) (9)

The transfer function h(s) can be obtained according to equation (9).

Order to

Then:

in summary, it can be seen from the formula (1) that when the movable plate is subjected to an external force, the movable plate has a natural frequency w₀When displacement occurs, the acceleration a of the movable polar plate movement is in a linear change relation with the change delta C of the capacitance between the movable polar plate and the fixed polar plate. From equation (11), the output and natural frequency of the A + g sensorRate w₀Inherent distance d between movable plate and two adjacent fixed plates and initial static capacitance C₀And has a linear relationship.

In practical applications, the MEMS chip and the ASIC substrate are electrically connected through a number of supports through which voltage signals are transmitted. Fig. 5 is a schematic diagram showing the connection of the ASIC substrate and the MEMS chip when a large number of supports are included. When the ASIC substrate is deformed under the action of external stress, the external stress can act on the supporting body, and then the MEMS chip is deformed under the stress of the supporting body. For example, fig. 6 shows a deformation diagram of the MEMS chip after being stressed by the supporting body in an exemplary embodiment. The deformed MEMS chip enables the movable polar plate to move, and further, capacitance change can be generated between the movable polar plate and the fixed polar plate. This receive external stress effect differential electric capacity, A + g sensor when no matter the portable polar plate does not move or move is in sensor output, all can superpose because MEMS chip takes place deformation and produces electric capacity, and then makes the acceleration of measurement and angular velocity output precision not high or even distortion.

Because the support body is formed by electrically connecting the MEMS chip and the ASIC substrate, stress is inevitably introduced when the A + g sensor is manufactured and packaged, so that the ASIC substrate is deformed. The deformed ASIC substrate transmits the stress to the MEMS chip through the support body, so that the MEMS chip is also deformed under the influence of the stress of the support body. The deformed MEMS chip influences the detection precision of the A + g sensor and even influences the normal work of the A + g sensor.

In view of this, the present disclosure provides an a + g sensor, in which a support body supporting a MEMS chip is disposed on an ASIC substrate, and a part of the support body is fixedly connected to the MEMS chip, and another part of the support body is connected to the MEMS chip in a lap joint manner.

In the present disclosure, a part of the support body is connected to the MEMS chip in a lap joint manner, so that the MEMS chip can be supported. On the other hand, when the ASIC substrate is deformed under the action of external stress, the supporting body in lap joint with the MEMS chip can not transmit the external stress to the MEMS chip, so that the stress from the supporting body on the MEMS chip is reduced, the influence of the deformation of the MEMS chip on the detection precision can be reduced, and the high detection precision of the acceleration gyro sensor is improved.

In addition, in the disclosure, part of the support body in the support body is fixedly connected with the MEMS chip, so that the transmission of electric signals between the ASIC substrate and the MEMS chip can be ensured, and a supporting effect can be achieved. Furthermore, the position of the support body fixedly connected with the ASIC substrate is arranged at the position of the support body on the ASIC substrate, and when the ASIC substrate is deformed under the action of external stress, the stress of the support body borne by the MEMS chip is at the position within a preset range, so that when the ASIC substrate is deformed under the action of external stress, the stress of the support body fixedly connected with the MEMS chip borne by the MEMS chip is reduced.

When the ASIC substrate deforms under the action of external stress, the position of the stress of the support body on the MEMS chip within the preset range may be a position where the distance between the support body and the set inductor and/or the set capacitor exceeds a set distance threshold, or may be a position located in the central area of the ASIC substrate.

FIG. 7 is a schematic diagram of an A + g sensor configuration, according to an exemplary embodiment. In the present embodiment, the a + g sensor includes a MEMS chip 1 and an ASIC substrate 2. The ASIC substrate 2 is provided with a support body for supporting the MEMS chip 1, one part of the support body 3 is fixedly connected with the MEMS chip 1, and the other part of the support body 3 is in lap joint with the MEMS chip 1.

It is understood that the number of the supporting bodies 3 fixedly connected or connected with the MEMS chip 1 in fig. 7 is only for illustrative purposes and is not meant to be limiting.

The ASIC substrate 2 may be a lead frame or a Printed Circuit Board (PCB). Depending on the design requirements, holes may be made in the lead frame or PCB at specific locations.

In order to minimize the stress applied to the MEMS chip 1 in the present disclosure, the detection accuracy of the a + g sensor is the highest, and the number of the support bodies 3 fixedly connected to the MEMS chip 1 is set to 1.

In an example of the present disclosure, the number of the supporting bodies 3 lap-jointed to the MEMS chip 1 is set to 0.

It is understood that the MEMS chip 1 is easily damaged by the stress of the support 3 fixedly connected to the MEMS chip 1. Moreover, the larger the number of supports 3 fixedly connected to the MEMS chip 1, the more likely the MEMS is to be subjected to the stress of the supports 3 and to be damaged. Therefore, in the embodiment of the present disclosure, according to actual requirements, if the requirement on the detection accuracy of the a + g sensor is not high and the requirement on the damage of the MEMS chip 1 is low, the number of the support bodies 3 fixedly connected to the MEMS chip 1 may be more than 1. For example, in order to ensure the stability, the number of the supports 3 fixedly connected between the MEMS chip 1 and the ASIC substrate 2 may be set to 3, and the position of the support 3 fixedly connected to the MEMS chip 1 may be set to a position away from the position affected by the external stress. When the ASIC substrate 2 is deformed by an external stress, it is possible to reduce the stress applied to the MEMS chip 1 from the support body 3 to be fixedly connected to the MEMS chip 1.

The support body 3 which supports the MEMS chip 1 is partially overlapped with the MEMS chip, so that when the ASIC substrate 2 is deformed under the action of external stress, the MEMS chip 1 cannot be influenced by the stress. And set up partial supporter 3 and MEMS chip 1 fixed connection to with this supporter 3 with MEMS chip 1 fixed connection set up on ASIC basement 2 and lie in when ASIC basement 2 receives external stress effect to take place to warp, the position of the stress of the supporter 3 that MEMS chip 1 receives is in the predetermined scope for when ASIC basement 2 receives external stress effect to take place to warp, can reduce MEMS chip 1 and receive the stress from supporter 3. When the ASIC substrate 2 is subjected to very small external stress and is deformed in a micrometer scale, the MEMS chip 1 may be deformed in a micro-shape or may not be deformed, as shown in fig. 8. Therefore, the influence of deformation of the MEMS chip 1 on the detection precision can be reduced, and the high detection precision of the acceleration gyro sensor is improved.

This is disclosed, can not take place deformation or take place micro-deformation's MEMS chip 1, avoided MEMS chip 1 to be damaged, also make A + g sensor's detection precision not influenced for A + g sensor can guarantee better linearity and detection range when exporting.

The support body 3 according to the present disclosure will be explained below. The support body 3 fixedly connected with the MEMS chip 1 according to the present disclosure may be disposed at a position where the force detection element is not distributed or in a region where the force detection element is less distributed in the ASIC substrate 2, so as to avoid transmitting the stress detected by the force detection element to the support body 3. The force detection element in the present disclosure may be one or more of an inductor, a capacitor, a vibrator, a speaker, and the like.

In an example of the present disclosure, a support body 3 fixedly connected to the MEMS chip 1 is provided at a set position of the ASIC substrate 2. The set position may be a position where the distance to the set inductance and/or the set capacitance exceeds a set distance threshold. The set inductance and/or set capacitance may be, for example, a large inductance and/or a large capacitance that may easily cause inductive howling or capacitive howling. For example, the set position may be a position that is a distance from the vibrator in the PCB circuit board that exceeds a preset threshold.

In this embodiment, the support 3 fixedly connected to the MEMS chip 1 is fixed to the ASIC substrate 2 at a predetermined position by a low-stress adhesive or a low-stress solder. Through this low stress glue or low stress solder is fixed, can play firm effect on the one hand, on the other hand can play the effect of buffering external stress, further reduces the influence of external stress to A + g sensor measurement accuracy. The low-stress adhesive in this embodiment may be a silicon adhesive or a silicone adhesive, and the low-stress solder may be a lead-tin solder.

In an example of the present disclosure, the supporting body 3 fixedly connected to the MEMS chip 1 is disposed in a central region of the ASIC substrate 2, so that the supporting body 3 fixedly connected to the MEMS chip 1 can stably support the MEMS chip 1, and external stress can be reduced to directly act on the supporting body 3, thereby further reducing the influence of the external stress on the measurement accuracy of the a + g sensor.

In another example of the present disclosure, a groove is provided on the ASIC substrate 2, and the support body 3 is embedded in the groove. Play the effect of buffering external stress through this recess, further reduce the influence of external stress to A + g sensor measurement accuracy.

The support body 3 is fixed in the groove of the ASIC substrate 2 through low-stress glue or low-stress solder, so that the support body 3 can stably support the MEMS chip 1, external stress can be reduced to directly act on the support body 3, and the influence of the external stress on the measurement precision of the A + g sensor is further reduced. The low-stress adhesive in the embodiment may be a silicon adhesive or a silicone adhesive, the low-stress solder may be a lead-tin solder or other equivalent solders, and the low-stress adhesive and the low-stress solder may be selected according to actual needs.

The support body 3 referred to in the present disclosure may be made of a material conducting electric current, for example, a bonding wire made of a conductive material, and is electrically connected by a wire bonding process or other equivalent processes.

In one example, the material of the support 3 fixedly connected to the MEMS chip 1 may be an elastic conductive material. The resilient conductive material may be, for example, a conductive glue. Utilize the supporter 3 that elasticity conducting material made, during electric connection MEMS chip 1 and ASIC base 2, when ASIC base 2 received external stress effect and takes place deformation, supporter 3 that elasticity conducting material made can be according to the direction of the stress behind the deformation of ASIC base 2, lengthen or shorten the supporter 3 with MEMS chip 1 fixed connection, with the stress that eliminates or less MEMS chip 1 receives, make MEMS chip 1 can not take place to deform or take place the micro-deformation, and then guarantee A + g sensor's detection precision.

It should be understood that the present disclosure is not limited to the material of the support 3 fixedly connected to the MEMS chip 1, and for example, the material of the support 3 fixedly connected to the MEMS chip 1 in the present disclosure may also be a conductive material such as a metal or a silicon-based material.

In the a + g sensor provided by the present disclosure, on the one hand, the number of the supporting bodies 3 fixedly connected with the MEMS chip 1 is relatively reduced, and the position of the supporting body 3 fixedly connected with the MEMS chip 1 is set at the position within the preset range of the stress of the supporting body received by the MEMS chip 1 when the ASIC substrate 2 is deformed by the external stress, so that the stress of the supporting body 3 fixedly connected with the MEMS chip 1 received by the MEMS chip 1 can be reduced. On the other hand, the support body 3 fixedly connected with the MEMS chip 1 is made of an elastic conductive material, so that when the ASIC substrate 2 is deformed by an external stress, the stress applied to the MEMS chip 1 from the support body 3 fixedly connected with the MEMS chip 1 can be reduced. Therefore, the A + g sensor provided by the disclosure can reduce the influence of deformation of the MEMS chip 1 on the detection precision, and improve the high detection precision of the acceleration gyro sensor.

Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.

It will be understood that the invention is not limited to the precise arrangements described above and shown in the drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the invention is limited only by the appended claims.

Claims

1. An acceleration gyro sensor comprises a Micro Electro Mechanical System (MEMS) chip and an Application Specific Integrated Circuit (ASIC) substrate, and is characterized in that a supporting body for supporting the MEMS chip is arranged on the ASIC substrate;

one part of the supporting bodies is fixedly connected with the MEMS chip, and the other part of the supporting bodies is in lap joint with the MEMS chip;

and the position of the support body fixedly connected with the MEMS chip on the ASIC substrate is positioned in the position of the stress of the support body on the MEMS chip in a preset range when the ASIC substrate is deformed under the action of external stress.

2. The acceleration gyro sensor of claim 1, wherein the number of supports fixedly connected to the MEMS chip is one.

3. The acceleration gyro sensor of claim 2, wherein the number of supports that are lap-joined to the MEMS chip is 0.

4. The acceleration gyrosensor according to any one of claims 1 to 3, wherein the position on the ASIC substrate of the support body fixedly connected to the MEMS chip is a position at which a distance between a set inductance and/or a set capacitance exceeds a set distance threshold.

5. The acceleration gyro sensor of claim 3, characterized in that the position of the support body fixedly connected with the MEMS chip on the ASIC substrate is located in the ASIC substrate central area.

6. The acceleration gyro sensor of claim 3, wherein the support body fixedly connected with the MEMS chip is fixed at the set position of the ASIC substrate by low stress glue or low stress solder.

7. The acceleration gyrosensor of claim 6, wherein the low stress gel is a silicon gel or a silicone gel and the low stress solder is a lead-tin solder.

8. The acceleration gyro sensor of claim 3, wherein the ASIC substrate is provided with a groove, the support body being embedded in the groove.

9. The acceleration gyro sensor of claim 8, wherein the support body is of unitary construction with the recess.

10. The acceleration gyro sensor of claim 1, wherein the support body fixedly connected to the MEMS chip is made of an elastic conductive material.