Micro acceleration sensor chip with high overload resistance and preparation method thereof

Abstract

The invention discloses a micro-acceleration sensor chip with high overload resistance and a preparation method thereof, and belongs to the field of silicon micro-accelerometers, and the micro-acceleration sensor chip comprises an upper cover plate, a lower cover plate and a sensitive chip which are bonded together. The sensitive chip comprises a fixed outer frame and two inertia sensing units, each inertia sensing unit comprises two inertia mass blocks, the outer side of each mass block is provided with a structure supporting beam which extends outwards and is connected with the fixed outer frame, and the inner side of each mass block is provided with a middle supporting beam which is connected with the other mass block; the upper side and the lower side of the middle supporting beam are connected with the two inertia mass blocks through the sensitive micro beams. An anti-overload structure is arranged below each mass block, and under large impact, the anti-overload structure makes contact with a stop gap on the fixed frame so as to resist structural damage caused by the impact. The overload structure is arranged on the symmetrical bending-tension-compression combined sensitive structure, large tail end displacement can be generated, locking gap machining is easy, and the high-frequency response and high-sensitivity characteristics of the sensor can be guaranteed.

Description

Technical Field

[0001] The present invention belongs to the technical field of silicon micro-accelerometers, and in particular relates to a micro-acceleration sensor chip with high overload resistance and a preparation method thereof. Background Art

[0002] An accelerometer is a sensor that measures the acceleration of an object's motion. Compared to traditional accelerometers, MEMS accelerometers offer advantages such as small size, low power consumption, mass production, and integration. Therefore, they are widely used in industrial control, automotive vibration monitoring, posture monitoring in consumer electronics, and the military. To meet the vibration monitoring needs of high-end equipment such as ultra-high-speed industrial machine tools, accelerometers often require high-frequency response characteristics to monitor vibrations across a wide range of frequencies. Furthermore, most industrial sensors operate in harsh environments, requiring high reliability. For example, the sudden stop of an ultra-high-speed metalworking machine can generate shock accelerations of up to several thousand g, a requirement currently unattainable by conventional high-frequency accelerometers on the market. Conventional MEMS high-frequency accelerometers, to ensure high-frequency response while maintaining a good signal-to-noise ratio, generally employ a stress-concentrated microbeam structure to enhance sensitivity. However, the overload resistance of current accelerometers relies primarily on the strength of the sensitive beam. The high stress concentration in the sensitive microbeam results in poor overload resistance, reducing device reliability and hindering widespread adoption in practical applications.

[0003] Another common method for improving overload resistance is to use a stop structure to achieve high overload resistance. However, for high-frequency sensors (e.g., with a natural frequency ≥ 25kHz), the maximum displacement of the proof mass when the sensitive beam reaches the breaking stress does not exceed 1μm. This line width combined with a large etching depth (~400μm) is not achievable with existing process systems. Summary of the Invention

[0004] The present invention provides a micro acceleration sensor chip with high overload resistance and a preparation method thereof, thereby improving the overload resistance of the high-frequency response micro acceleration sensor chip.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: In a first aspect, the present invention provides a micro-acceleration sensor chip with high overload resistance, comprising an upper cover plate, a sensitive chip, and a lower cover plate bonded together in sequence. The sensitive chip includes two inertial units, each of which includes an inertial mass block group and an anti-overload structural beam. The inertial mass block group includes two inertial mass blocks connected by an intermediate hinge beam, two sensitive micro-beams connected between the two inertial mass blocks, and doped sensitive resistors on the upper portions of the sensitive micro-beams; both ends of the inertial mass block group are connected to a fixed frame via side support beams; a stop gap is defined on the inner side of the fixed frame; both sides of the inertial mass block group are respectively connected to one end of the anti-overload structural beam, and the other end of the anti-overload structural beam extends into the stop gap.

[0006] Furthermore, the stop gap is only formed in the top silicon layer.

[0007] Furthermore, the anti-overload structural beam in each inertial unit is symmetrically distributed at the end points of the two inertial mass blocks with the geometric center of the middle hinge beam as the center of symmetry.

[0008] Furthermore, the anti-overload structural beams in each inertial unit are symmetrically distributed at both end points of the same inertial mass block with the symmetry axis of the middle hinge beam as the symmetry axis.

[0009] Furthermore, the inertial mass block is an I-shaped column as a whole.

[0010] Furthermore, the thickness of the side support beam is the same as the thickness of the inertial mass block.

[0011] Furthermore, the dimensions of a micro-accelerometer chip with a range of 100 g and a frequency response of 10 kHz and high overload resistance are: length × width × height = (1.9 × 2.7 × 0.4~2.0 × 2.9 × 0.6) mm 3 .

[0012] Furthermore, the volume of the inertial mass block is 0.18~0.200.19 mm 3 .

[0013] Furthermore, the width of the side support beam is greater than the width of the middle hinge beam.

[0014] In a second aspect, the present invention provides a method for preparing a micro acceleration sensor chip with high overload resistance, comprising the following steps: S1, forming a doped sensitive resistor in the sensitive micro-beam area on the front side of the silicon wafer; S2, photolithography to obtain a lead pattern on the front side of the silicon wafer, sputtering metal and then preparing gold leads by lift-off; S3, etching the active area of ​​the mass block on the back side of the SOI silicon wafer; S4. Etching the shapes of the side support beams, hinge beams, inertial mass blocks, anti-overload structural beams, and the lower half of the fixed frame, as well as the accommodating grooves, on the back side of the SOI silicon wafer, etching to the buried oxide layer; S5, bonding the back side of the silicon wafer to the lower cover plate; S6. Etching side support beams, a middle hinge beam, an inertial mass block, an anti-overload structural beam, an upper portion of a fixed frame, and a stop gap on the front side of the silicon wafer; S7. Bond the front side of the silicon wafer to the upper cover plate.

[0015] Compared with the prior art, the present invention has at least the following beneficial technical effects: 1) This invention utilizes an anti-overload structural beam within the mass block to enable the sensor to withstand significant impacts. When the sensor chip is impacted, the anti-overload structural beam contacts the inner wall of the stop gap on the fixed frame to resist structural damage. The sensor's overload resistance reaches 19157.93 to 19738.95 g, matching or even exceeding the performance of existing IEPE vibration accelerometers. Furthermore, because the stop gap acts as a lever to amplify displacement, generating large end displacements, the stop gap can be relatively large (≥2 μm). Etching the stop gap only in the top silicon layer increases the line width compared to traditional stop structures, facilitating fabrication.

[0016] 2) The present invention utilizes high-rigidity side support beams of the same thickness as the mass block to connect the mass block to the fixed frame, and a high-rigidity intermediate hinge beam of the same thickness as the mass block to connect the two masses. Furthermore, an anti-overload structural beam extending from the mass block and having the same thickness as the mass block is employed. This results in a natural frequency of the entire chip greater than 25 kHz, thereby ensuring high-frequency response performance and a wide range of applications.

[0017] 3) On the basis of high solid frequency and high overload resistance, since the sensor output is proportional to the difference between axial and longitudinal stresses, the present invention uses pure axial strain sensitive microbeams symmetrically arranged on the mass block as sensitive elements, which can significantly improve the energy conversion efficiency and sensitivity, thereby effectively ensuring the collection of weak characteristic signals in the vibration and impact fields.

[0018] This invention provides a method for fabricating a micro-acceleration sensor chip with high overload resistance. Using an SOI silicon wafer to create the sensor allows for precise control of the thickness of the micro-beam. Furthermore, due to the insulating and thermally insulating properties of the SOI silicon wafer, the sensor produced using this process exhibits low ambient noise and good temperature resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1a This is a schematic diagram of the overall structure of the sensitive chip with the anti-overload structure centrally and symmetrically arranged on two mass blocks; Figure 1bIt is a schematic diagram of the overall structure of the sensitive chip with an anti-overload structure axially symmetrically arranged on a mass block; Figure 2a This is a schematic diagram of the structure of the sensitive chip with anti-overload structure arranged symmetrically in the center; Figure 2b This is a schematic diagram of the structure of the sensitive chip with an axisymmetric arrangement of an anti-overload structure; Figure 3a This is the simplified force-deformation diagram of a single inertial unit when the sensitive chip is loaded in the sensitive direction; Figure 3b The sensitive chip is loaded in the sensitive direction (Y-axis), and the chip's overall sensing circuit diagram; Figure 3c The sensitive chip is loaded in the sensitive direction (X-axis), and the overall sensing circuit diagram of the chip; Figure 3d The chip is loaded in the sensitive direction (Z axis), and the overall sensing circuit diagram of the chip; Figure 4a This is a schematic diagram of the impact load resistance principle of Example 2 of the present invention; Figure 4b This is a schematic diagram of the impact load resistance principle of Example 2 of the present invention; Figure 5 It is a processing flow chart of the present invention; Figure 6 This is a graph showing the acceleration output results of the control sensor and the patented sensor under impact; Figure 7 It is the test result of the maximum working acceleration of each sensor.

[0020] In the attached figure: 1. Upper cover; 2. Sensitive chip; 3. Inertial mass block; 4. Anti-overload structural beam; 5. Lower cover; 6. Side support beam; 7. Middle hinge beam; 8. Sensitive microbeam; 9. Stop gap; 10. Fixed frame; 11. Mass block active area. DETAILED DESCRIPTION

[0021] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0022] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0023] It should be noted that when an element is referred to as being "disposed on" another element, it may be directly on the other element or there may be another element centered thereon. When an element is considered to be "connected" to another element, it may be directly connected to the other element or there may be another element centered thereon at the same time. The terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", etc. used herein indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used herein in the specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0025] A micro-acceleration sensor chip with high overload resistance comprises a cover plate 1, a sensitive chip 2, and a lower cover plate 5, which are sequentially bonded together. The sensitive chip 2 is composed of two fixed frames 10 and two inertial units. Each inertial unit includes side support beams 6, a sensitive micro-beam 8, an inertial mass 3, an overload-resistant structural beam 4 connected to the inertial unit mass 3, and an intermediate hinge beam 7. The inertial mass 3 is connected to the fixed frame 10 via the side support beams 6 to form a cantilever beam-mass system. The two sensitive micro-beams 8 are symmetrically distributed around the intermediate hinge beam 7 and connect the two inertial mass 3. Each sensitive micro-beam 8 has a doped sensitive resistor on it to form a Wheatstone bridge for sensitive directional motion sensing and decoupling. The doped sensitive resistor is doped only on the top silicon.

[0026] The inertial mass block 3 is an I-shaped column as a whole to improve its structural strength. The fixed frame 10 is connected to the inertial mass block 3 via side support beams 6. The side support beams 6 are parallel to the upper and lower bases of the inertial mass block 3 in length and are connected to the middle position of the upper and lower bases of the I-shaped inertial mass block 3 to connect the fixed frame 10 to the I-shaped inertial mass block 3. The thickness of the side support beams 6 is the same as that of the inertial mass block 3.

[0027] The following are specific embodiments. It should be noted that these embodiments are preferred examples of the present invention and are used to help those skilled in the art understand the present invention, but the present invention is not limited to these embodiments.

[0028] Example 1 like Figure 1a and Figure 2a As shown, a micro-acceleration sensor chip with high overload resistance performance includes three parts: a sensitive chip 2, an upper cover plate 1, and a lower cover plate 5 bonded together. The sensitive chip 2 consists of two fixed frames 10 and two inertial units arranged in parallel between the two fixed frames 10. Each inertial unit consists of two inertial mass blocks 3, side support beams 6, sensitive micro-beams 8, anti-overload structural beams 4, and a stop gap 9 opened on the fixed frame 10. Two stop gaps 9 are opened on the inner side of each fixed frame 10. Below the stop gap 9 is a receiving groove connected to the stop gap 9. The width and depth ratio of the receiving groove is 1:10, wherein the width of the stop gap 9 is 0.2 mm, and the size of the stop gap 9 is length × width × height = 0.002 × 0.2 × 0.01 mm. 3 , processed only on the top silicon layer. Each inertial mass 3 is I-shaped, with side support beams 6 extending outward and connected to the fixed frame 10 on its outer side. An intermediate hinge beam 7 connected to another inertial mass 3 is located in the middle of its inner side. The width of the side support beams 6 is greater than that of the intermediate hinge beam 7. Sensitive microbeams 8 are located on both the upper and lower sides of the intermediate hinge beam 7, connecting the two inertial mass 3. Each inertial mass 3 is provided with an anti-overload structural beam 4, which is arranged symmetrically around the center. One end of the anti-overload structural beam 4 is connected to the inertial mass 3, and the other end extends into the stop gap 9. The width of the sensitive microbeam 8 is smaller than that of the anti-overload structural beam 4. Each sensitive microbeam 8 has a doped sensitive resistor connected to the inertial mass 3, forming a Wheatstone bridge with gold wires to sense axial motion. The gold wires have square pads at the ends, and all sensitive resistors have the same initial resistance. The side support beams 6 have a relatively large rigidity, which is used to improve the overall rigidity of the chip, thereby improving the natural frequency, bandwidth and frequency response speed.

[0029] For a micro-accelerometer with high overload resistance, taking the requirements of 100g range and 10kHz frequency response as an example, its design dimensions are: 1) Overall dimensions: length × width × height = (1.9 × 2.7 × 0.4 ~ 2.0 × 2.9 × 0.6) mm 3 The dimensions of the sensitive micro-beam 8 are: length × width × height = (0.04 × 0.004 × 0.01 ~ 0.06 × 0.006 × 0.01) mm 3 The dimensions of the side support beam 6 are: length × width × height = (0.11 × 0.02 × 0.4 ~ 0.13 × 0.04 × 0.6) mm 3 The dimensions of the middle hinge beam 7 are: length × width × height = (0.31 × 0.02 × 0.4 ~ 0.33 × 0.04 × 0.6) mm 3The dimensions of a single anti-overload structural beam 4 are: length × width × height = (1.00 × 0.05 × 0.4 ~ 1.12 × 0.07 × 0.4) mm 3 The volume of a single inertial mass block 3 is: equivalent bottom area × height = (0.18~0.200.19) mm 3 .

[0030] Example 2 Reference Figure 1b and Figure 2b The only difference between this embodiment and embodiment 1 is the arrangement of the anti-overload structural beam 4. In this embodiment, only one inertial mass block 3 in each inertial unit is connected to the anti-overload structural beam 4. The specific structure is as follows: the two ends of the inertial mass block 3 on the same side are connected to one end of two anti-overload structural beams 4. The two anti-overload structural beams 4 surround the other inertial mass block 3, and the other ends extend into the stop gap 9.

[0031] The anti-overload structural beam 4 of the present invention can be arranged on the same inertial mass block 3 or on two inertial mass blocks 3 to improve the reliability of the sensor. The working principles are the same, so the working principles of the two sensors are uniformly explained at the same time. Working principle: Figure 3a 、 Figure 3b 、 Figure 3c and Figure 3d As shown in FIG, when acceleration is applied along the sensitive direction (Y axis) of the acceleration sensor, taking an inertial unit as an example, the sensitive micro-beam where the doped sensitive resistor R1 is located is in a compressed state, and the sensitive micro-beam where the doped sensitive resistor R2 is located is in a tensile state, resulting in opposite changes in their resistance values, as shown in FIG. Figure 3b As shown, the resistance values ​​of R1 and R3 change at the same rate, and the resistance values ​​of R2 and R4 change at the same rate. According to the Wheatstone bridge differential output formula ΔR=(R2+R4)-(R1+R3), the overall resistance change of the Wheatstone bridge increases, thereby improving the sensitivity of the sensor. For acceleration in the non-sensitive direction (X-axis), the bridge resistance changes as shown below: Figure 3c As shown, the resistance change of the differential output ΔR=0; for acceleration in the non-sensitive direction (Z axis), the bridge resistance changes as follows Figure 3d As shown, the resistance change of the differential output ΔR=0. This resistor arrangement can effectively eliminate the interference of acceleration in non-sensitive directions on the sensor output signal. Figure 2a and Figure 2bIn the figure, the anti-overload structural beam 4 in each inertial unit is centered on the middle hinge beam 7 and is symmetrically distributed at the end points of the two inertial mass blocks 3, that is, the points where the displacement of the inertial mass blocks 3 is the largest, thereby playing a displacement amplification role. When the chip as a whole is subjected to a large impact load, the end of the anti-overload structural beam 4 can generate a large enough displacement to contact the inner wall of the stop gap 9 on the fixed frame, thereby offsetting the destructive effect of the large impact on the sensitive micro-beam 8. Figure 4a and Figure 4b .

[0032] Reference Figure 5 The present invention provides a method for manufacturing a micro acceleration sensor with high overload resistance as follows: 1)Reference Figure 5 In (a) and (b), a P-type SOI silicon wafer was used. The top silicon layer of the P-type SOI wafer was 10μm thick, the middle buried oxide layer was 1μm thick, and the bottom silicon layer was 400μm thick. After cleaning the silicon wafer surface, a 200-300nm thick SiO2 film was deposited on the SOI wafer using plasma enhanced chemical vapor deposition (PECVD). 2)Reference Figure 5 In (c), photolithography is performed on the front side of the silicon wafer, and then a buffered oxide etchant (BOE solution) is used to remove the exposed SiO2. The sensitive micro-beam 8 area where the SiO2 is removed is used as a window for boron diffusion to form a doped sensitive resistor. 3) Metallization: Refer to Figure 5 In (d), a gold lead pattern is obtained by photolithography on the front side of the silicon wafer. After metal sputtering, the gold lead and the square pad at the end of the lead are prepared by lift-off. Then, alloying annealing is performed to improve the stability of the signal transmitted on the gold lead. 4) Back active area etching: refer to Figure 5 In (e), the active area 11 of the mass block is formed by photolithography and inductively coupled plasma etching (ICP) on the back side of the SOI silicon wafer; 5) Deep etching on the back: refer to Figure 5 In (f), backside photolithography and ICP etching are used to form the shape of the side support beam 6, hinge beam 7, inertial mass block 3, anti-overload structural beam 4 and the lower half of the fixed frame 10, as well as the accommodating groove, and are etched to the buried oxide layer; 6)Reference Figure 5 In (g), BF33 glass is used as the lower cover plate 5, and the back side of the silicon wafer is connected to the BF33 glass by anodic bonding; 7) Front structure release: refer to Figure 5 In (h), after photolithography on the front side of the silicon wafer, ICP etching is performed on the top silicon layer to form the shapes of the side support beams 6, hinge beams 7, mass block 3, anti-overload structural beams 4, the upper half of the fixed frame 10, and the stop gap 9. Thus, the mass block 3, anti-overload structural beams 4, side support beams 6, middle hinge beams 7, stop gaps 9, and fixed frame 10 are obtained; 8) Positive anodic bonding: refer to Figure 5 In (h), another BF33 glass is used as the upper cover plate 1, and the front surface of the silicon wafer is connected to the BF33 glass by anodic bonding; 9) Device packaging, including: a. Use a laser scribing machine to scribing along the scribing path to divide the accelerometer chips into multiple accelerometer chips; b. The acceleration sensor chip is attached to the stainless steel square tube shell with AB glue; c. Use a gold ball bonder to bond the thin gold wires to the pads on the sensitive chip one by one; d. Install the sealed shell cover on the shell and seal it with AB glue.

[0033] Six sensors were selected to test their working conditions under impact acceleration. The sensors numbered 1, 2, and 3 are control structures, that is, they have no overload beam structure. The sensors numbered 4, 5, and 6 are the patented structures, that is, they have an anti-overload beam structure. The working conditions of these sensors are as follows: Figure 6 and Figure 7 As shown, Figure 6 In the figure, the vertical axis represents the sensor's output voltage, and the horizontal axis represents the impact acceleration experienced by the sensor. The figure shows that the high-overload structure sensor still functions normally when the impact acceleration ranges from 19157.93 to 19738.95 g, while the control structure sensor fails when the acceleration exceeds the range of 8112.79 to 8524.72 g.

[0034] The measurement results show that the high-overload structure sensor's overload resistance has increased by 143.4%. The sensor's natural frequency is 31.13kHz.

[0035] The term "consisting of" when describing a combination should include the identified elements, ingredients, components, or steps as well as other elements, ingredients, components, or steps that do not materially affect the basic novel characteristic of the combination. The use of the terms "comprising" or "including" to describe a combination of elements, ingredients, components, or steps herein also contemplates embodiments consisting essentially of these elements, ingredients, components, or steps. The use of the term "may" herein is intended to indicate that any of the attributes described as "may" be optional.

[0036] Multiple elements, ingredients, parts or steps can be provided by a single integrated element, ingredient, part or step. Alternatively, a single integrated element, ingredient, part or step can be divided into separate multiple elements, ingredients, parts or steps. The disclosure of "a" or "an" to describe an element, ingredient, part or step is not intended to exclude other elements, ingredients, parts or steps.

[0037] It should be understood that the above description is for illustrative purposes only and is not intended to be limiting. Many embodiments and many applications beyond the examples provided will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of the present teachings should not be determined with reference to the above description, but rather with reference to the preceding claims and the full scope of equivalents to which such claims are entitled. For the purpose of completeness, all articles and references, including disclosures of patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein from the preceding claims is not a disclaimer of such subject matter, nor should it be considered that the applicants did not consider such subject matter to be part of the disclosed inventive subject matter.

Claims

1. A micro acceleration sensor chip with high overload resistance, characterized in that: The invention comprises an upper cover plate (1), a sensitive chip (2) and a lower cover plate (5) which are bonded to each other in sequence, wherein the sensitive chip (2) comprises two inertial units, each of which comprises an inertial mass block group and an anti-overload structural beam (4), wherein the inertial mass block group comprises two inertial mass blocks (3) connected via an intermediate hinge beam (7), and two sensitive micro-beams (8) are connected between the two inertial mass blocks (3), wherein the upper portion of the sensitive micro-beams (8) has a doped sensitive resistor; both ends of the inertial mass block group are connected to a fixed frame (10) via a side support beam (6); and a stop gap (9) is provided on the inner side of the fixed frame (10); Both sides of the inertial mass block group are respectively connected to one end of the anti-overload structural beam (4), and the other end of the anti-overload structural beam (4) extends into the stop gap (9).

2. The micro acceleration sensor chip with high overload resistance according to claim 1, characterized in that: The stop gap (9) is formed only in the top silicon layer.

3. The micro acceleration sensor chip with high overload resistance according to claim 1, characterized in that: The anti-overload structural beam (4) in each inertial unit is symmetrically distributed at the end points of the two inertial mass blocks (3) with the geometric center of the middle hinge beam (7) as the center of symmetry.

4. The micro acceleration sensor chip with high overload resistance according to claim 1, characterized in that: The anti-overload structural beam (4) in each inertial unit is symmetrically distributed at both end points of the same inertial mass block (3) with the symmetry axis of the middle hinge beam (7) as the symmetry axis.

5. The micro acceleration sensor chip with high overload resistance according to claim 1, characterized in that: The inertial mass block (3) is an I-shaped column as a whole.

6. The micro acceleration sensor chip with high overload resistance according to claim 1, characterized in that: The thickness of the side support beam (6) is the same as the thickness of the inertial mass block (3).

7. The micro acceleration sensor chip with high overload resistance according to claim 1, characterized in that: The dimensions of a micro-accelerometer chip with a 100 g range and a 10 kHz frequency response and high overload resistance are: length × width × height = (1.9 × 2.7 × 0.4 ~ 2.0 × 2.9 × 0.6) mm 3 .

8. The micro acceleration sensor chip with high overload resistance according to claim 1 or 7, characterized in that: The volume of the inertial mass block (3) is 0.18~0.200.19 mm 3 .

9. The micro acceleration sensor chip with high overload resistance according to claim 1 or 7, characterized in that: The width of the side support beam (6) is greater than the width of the middle hinge beam (7).

10. The method for preparing a micro acceleration sensor chip with high overload resistance according to claim 1, characterized in that: The following steps are involved: S1, forming a doped sensitive resistor in the sensitive micro-beam (8) area on the front side of the silicon wafer; S2, photolithography to obtain a lead pattern on the front side of the silicon wafer, sputtering metal and then preparing gold leads by lift-off; S3, etching a mass block active area (11) on the back side of the SOI silicon wafer; S4, etching the shape of the side support beam (6), the hinge beam (7), the inertial mass block (3), the anti-overload structural beam (4) and the lower half of the fixed frame (10) and the accommodating groove on the back side of the SOI silicon wafer, and etching to the buried oxide layer; S5, bonding the back side of the silicon wafer to the lower cover plate (5); S6, etching the side support beam (6), the middle hinge beam (7), the inertial mass block (3), the anti-overload structural beam (4), the upper half of the fixed frame (10) and the stop gap (9) on the front side of the silicon wafer; S7, bonding the front side of the silicon wafer to the upper cover plate (1).

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