Piezoresistive multi-range MEMS pressure sensor and processing method thereof

Abstract

The invention relates to the technical field of pressure sensors, and discloses a piezoresistive multi-range MEMS pressure sensor and a processing method thereof. The piezoresistive multi-range MEMS pressure sensor comprises: a pressed diaphragm; the mass blocks comprise a central mass block and a fixed mass block; the insulating layer is clamped between the pressed diaphragm and the mass block; the piezoresistor is arranged on one side, deviating from the mass block, of the pressed diaphragm; the at least two supporting frames are located in the pressure groove, each supporting frame surrounds the center mass block and is spaced from the center mass block, the supporting frame adjacent to the center mass block is connected with the center mass block through a first connecting beam, and the supporting frame adjacent to the fixed mass block is connected with the fixed mass block through a second connecting beam; every two adjacent supporting frames are connected through a third connecting beam. The piezoresistive multi-range MEMS pressure sensor disclosed by the invention is simple in structure and easy to process, and not only realizes multi-range acting force detection, but also realizes micro-range high overload measurement.

Description

Technical Field

[0001] This invention relates to the field of pressure sensor technology, and in particular to a piezoresistive multi-range MEMS pressure sensor and its fabrication method. Background Technology

[0002] Existing multi-range MEMS pressure sensors typically employ multiple independent pressure-sensitive chips to detect different ranges, resulting in large sensor size, low integration, and complex signal processing circuitry, increasing system power consumption and cost. Furthermore, the discrete multi-chip design requires separate packaging and calibration, which not only complicates manufacturing processes but may also affect overall reliability. Although some products attempt to integrate multiple pressure ranges onto a single chip, existing solutions mostly rely on complex multilayer film structures or heterogeneous material combinations, which are not only difficult to process but also prone to introducing residual stress, affecting the long-term stability of the sensor. At the same time, such structures have stringent requirements for process consistency, leading to limited yield and high production costs. Summary of the Invention

[0003] Based on the above, the purpose of this invention is to provide a piezoresistive multi-range MEMS pressure sensor and its processing method, which has a simple structure, good stability, is easy to process, has a high yield rate and low production cost, and can realize high overload measurement of small ranges.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] Pressure-bearing diaphragm;

[0006] The mass block includes a central mass block and a fixed mass block arranged at intervals. The central mass block is located at the center of the pressure-bearing diaphragm, and the fixed mass block is located at the edge of the pressure-bearing diaphragm. The fixed mass block, the central mass block, and the pressure-bearing diaphragm form a pressure groove.

[0007] An insulating layer is sandwiched between the pressure-bearing diaphragm and the mass block;

[0008] A varistor is disposed on the side of the pressure-bearing diaphragm away from the mass block and facing the pressure groove;

[0009] At least two support frames are located within the pressure groove. Each support frame surrounds and is spaced apart from the central mass block. From the central mass block toward the fixed mass block, at least two support frames are distributed sequentially at intervals. Each support frame faces the pressure-bearing diaphragm and forms an insulating gap with the pressure-bearing diaphragm. The support frame adjacent to the central mass block is connected to the central mass block through a first connecting beam, the support frame adjacent to the fixed mass block is connected to the fixed mass block through a second connecting beam, and two adjacent support frames are connected through a third connecting beam.

[0010] As a preferred embodiment of a piezoresistive multi-range MEMS pressure sensor, the piezoresistive multi-range MEMS pressure sensor further includes a substrate, which is fixed on the fixed mass block, the support frame, the first connecting beam, the second connecting beam and the third connecting beam and surrounds the pressure groove to form a vacuum cavity, and the substrate is spaced apart from the central mass block.

[0011] As a preferred embodiment of a piezoresistive multi-range MEMS pressure sensor, the number of the first connecting beams is at least two and is an even number, and they are symmetrically distributed along the first and second perpendicular directions; or, the number of the first connecting beams is at least three and is an odd number, and they are centrally symmetrically distributed with the geometric center of the central mass block as the center of symmetry.

[0012] The number of the second connecting beams is at least two and is an even number, and they are symmetrically distributed along the first and second perpendicular directions; or, the number of the second connecting beams is at least three and is an odd number, and they are centrally symmetrically distributed with the geometric center of the central mass block as the center of symmetry.

[0013] The number of the third connecting beams is at least two and an even number, and they are symmetrically distributed along the first and second perpendicular directions; or, at least two of the support frames have the same shape, the number of the third connecting beams is at least three and an odd number, and they are centrally symmetrically distributed with the geometric center of the support frame as the center of symmetry.

[0014] As a preferred embodiment of a piezoresistive multi-range MEMS pressure sensor, the first connecting beam, the second connecting beam, and the third connecting beam are all straight beams.

[0015] As a preferred embodiment of a piezoresistive multi-range MEMS pressure sensor, the geometric centers of at least two of the support frames coincide with the geometric center of the central mass block, and each of the support frames is a closed frame connected end to end.

[0016] As a preferred embodiment of a piezoresistive multi-range MEMS pressure sensor, the pressure groove between the support frame adjacent to the fixed mass block and the fixed mass block is a pressure outer groove, and the piezoresistor is directly opposite the pressure outer groove.

[0017] As a preferred embodiment of a piezoresistive multi-range MEMS pressure sensor, the piezoresistive multi-range MEMS pressure sensor further includes four metal PADs, and the number of piezoresistors is four. The four piezoresistors and the four metal PADs are electrically connected to form a Wheatstone bridge.

[0018] A method for fabricating a piezoresistive multi-range MEMS pressure sensor applicable to any of the above schemes, comprising:

[0019] A first groove, a second groove, and a third groove are formed on a first silicon substrate. The first silicon substrate consists of a central bump, a support pillar, and a fixing bump, arranged from the inside out. The number of support pillars is at least two.

[0020] A second silicon substrate with an insulating layer is fixed on the first silicon substrate, and the insulating layer is sandwiched between the first silicon substrate and the second silicon substrate;

[0021] A varistor is formed on the second silicon substrate;

[0022] A connecting groove is formed on the side of the first silicon substrate away from the insulating layer. The connecting groove communicates with the first groove, the second groove, and the third groove. The support pillar forms a support frame. The central bump forms a central mass block. The fixed bump forms a fixed mass block. At the same time, a first connecting beam, a second connecting beam, and a third connecting beam are formed at the bottom of the first silicon substrate. The two ends of the first connecting beam are respectively connected to the central mass block and the support frame. The two ends of the second connecting beam are respectively connected to the support frame and the fixed mass block. The two ends of the third connecting beam are respectively connected to the two adjacent support frames.

[0023] The insulating layer opposite the support frame, the first groove, the second groove, and the third groove is removed, and a pressure-bearing diaphragm is formed on the second silicon substrate. An insulating gap is formed between the pressure-bearing diaphragm and the support frame, and the first groove, the second groove, and the third groove form a pressure groove.

[0024] In a preferred embodiment of a fabrication method for a piezoresistive multi-range MEMS pressure sensor, four metal PADs are formed on the side of the second silicon substrate away from the first silicon substrate. The number of piezoresistive resistors is four, and the four piezoresistive resistors are electrically connected to the four metal PADs to form a Wheatstone bridge.

[0025] In a preferred embodiment of a fabrication method for a piezoresistive multi-range MEMS pressure sensor, a substrate is fixed on the side of the first silicon substrate away from the insulating layer, and the pressure groove forms a vacuum cavity.

[0026] The beneficial effects of this invention are as follows:

[0027] The piezoresistive multi-range MEMS pressure sensor disclosed in this invention has a simple structure, good stability, and is easy to manufacture. It not only realizes the force detection function of multiple pressure ranges integrated into a single chip, but also realizes high overload measurement of small ranges. When detecting force, the pressure diaphragm deforms under the pressure of the force. Before the pressure diaphragm contacts the support frame near the central mass block, the piezoresistive multi-range MEMS pressure sensor can detect small forces and realize small pressure range detection. As the external force increases, the pressure diaphragm contacts each support frame from the inside to the outside in sequence until it contacts the support frame near the fixed mass block, realizing the force detection of the maximum pressure range.

[0028] The piezoresistive multi-range MEMS pressure sensor manufacturing method disclosed in this invention is easy to manufacture, and the manufactured piezoresistive multi-range MEMS pressure sensor can realize the force detection function of multiple pressure ranges integrated on a single chip. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the content of the embodiments of the present invention and these drawings without creative effort.

[0030] Figure 1 This is a bottom view of the piezoresistive multi-range MEMS pressure sensor provided in a specific embodiment of the present invention, excluding the substrate;

[0031] Figure 2 yes Figure 1 Sectional view at AA after adding the base;

[0032] Figure 3 yes Figure 1 Sectional view at BB after adding the base;

[0033] Figure 4 This is a top view of the piezoresistive multi-range MEMS pressure sensor provided in a specific embodiment of the present invention;

[0034] Figures 5 to 10 This is a process diagram illustrating the fabrication method of a piezoresistive multi-range MEMS pressure sensor provided in a specific embodiment of the present invention.

[0035] In the picture:

[0036] 11. Pressure-bearing diaphragm; 12. Varistor; 13. Metal PAD;

[0037] 20. Pressure groove; 201. External pressure groove; 21. Central mass block; 22. Fixed mass block; 23. Support frame;

[0038] 3. Insulation layer;

[0039] 41. First connecting beam; 42. Second connecting beam; 43. Third connecting beam;

[0040] 5. Base;

[0041] 61. First silicon substrate; 6101. First groove; 6102. Second groove; 6103. Third groove; 6104. Connecting groove; 611. Central bump; 612. Support post; 613. Fixing bump;

[0042] 7. Second silicon substrate. Detailed Implementation

[0043] To make the technical problems solved by the present invention, the technical solutions adopted, and the technical effects achieved clearer, the technical solutions of the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The terms "first position" and "second position" refer to two different positions.

[0045] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections or detachable connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; or internal connections between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0046] This embodiment provides a piezoresistive multi-range MEMS pressure sensor, such as... Figures 1 to 4As shown, the device includes a pressure-bearing diaphragm 11, a mass block, an insulating layer 3, a varistor 12, and two support frames 23. The mass block includes a central mass block 21 and a fixed mass block 22 spaced apart. The central mass block 21 is located at the center of the pressure-bearing diaphragm 11, and the fixed mass block 22 is located at the edge of the pressure-bearing diaphragm 11. The fixed mass block 22, the central mass block 21, and the pressure-bearing diaphragm 11 form a pressure groove 20. The insulating layer 3 is sandwiched between the pressure-bearing diaphragm 11 and the mass block. The varistor 12 is located on the side of the pressure-bearing diaphragm 11 away from the mass block and facing the pressure groove 20. The two support frames 23 are positioned... Within the pressure groove 20, each support frame 23 surrounds and is spaced apart from the central mass block 21. From the central mass block 21 toward the fixed mass block 22, two support frames 23 are distributed in sequence at intervals. Each support frame 23 is directly opposite the pressure-bearing diaphragm 11 and forms an insulating gap with the pressure-bearing diaphragm 11. The support frame 23 adjacent to the central mass block 21 is connected to the central mass block 21 through a first connecting beam 41, and the support frame 23 adjacent to the fixed mass block 22 is connected to the fixed mass block 22 through a second connecting beam 42. Two adjacent support frames 23 are connected through a third connecting beam 43.

[0047] When the pressure-bearing diaphragm 11 is subjected to a force, the area of ​​the portion of the pressure-bearing diaphragm 11 that can continuously deform with the force is defined as the equivalent area of ​​the pressure-bearing diaphragm 11. When detecting the force, if the force is small, the equivalent area of ​​the pressure-bearing diaphragm 11 is large and the overall deformation is small. Since the deformation of the middle part of the pressure-bearing diaphragm 11 is greater than that of the outside, the pressure-bearing diaphragm 11 first contacts the support frame 23 near the central mass block 21. At this time, the middle part of the pressure-bearing diaphragm 11 will not continue to deform, and the equivalent area of ​​the pressure-bearing diaphragm 11 decreases. After that, the force continues to increase, and the deformation of the pressure-bearing diaphragm 11 increases until the pressure-bearing diaphragm 11 contacts the support frame 23 near the fixed mass block 22. At this time, the measurement value of the piezoresistive multi-range MEMS pressure sensor reaches its maximum. It should be noted that in other embodiments of the present invention, the number of support frames 23 is not limited to two in this embodiment, but can also be three, four or more. In this case, the piezoresistive multi-range MEMS pressure sensor has three, four or more pressure ranges, and the number of support frames 23 is set according to actual needs.

[0048] The piezoresistive multi-range MEMS pressure sensor provided in this embodiment has a simple structure, good stability, and is easy to manufacture. It not only realizes the force detection function of multiple pressure ranges integrated into a single chip, but also realizes high overload measurement of small ranges. When detecting force, the pressure diaphragm 11 deforms under the pressure of the force. Before the pressure diaphragm 11 contacts the support frame 23 near the central mass block 21, the piezoresistive multi-range MEMS pressure sensor can detect small forces and realize small pressure range detection. As the external force increases, the pressure diaphragm 11 contacts each support frame 23 from the inside to the outside in sequence until it contacts the support frame 23 near the fixed mass block 22, realizing the force detection of the maximum pressure range.

[0049] In this embodiment, the geometric centers of both support frames 23 coincide with the geometric center of the central mass block 21, and each support frame 23 is a closed frame connected end to end. Figure 1 As shown, the closed frame is a quadrilateral frame, and two quadrilateral frames form a square frame. It should be noted that in other embodiments of the present invention, the support frame 23 can also be a circular frame or a closed frame of other shapes, and the number of support frames 23 can be three or more. The geometric centers of these support frames 23 coincide, and each support frame 23 is a closed frame, which is set according to actual needs.

[0050] like Figure 1 As shown, in this embodiment, the first connecting beam 41, the second connecting beam 42, and the third connecting beam 43 are all straight beams. There are four of each type. The central mass block 21 is a first square mass block, and the fixed mass block 22 is a second square mass block. The four first connecting beams 41 are connected to the four corners of the first square mass block and the four corners of a support frame 23, respectively, and are symmetrically distributed along the first and second directions, which are perpendicular to each other. The four second connecting beams 42 are connected to the four corners of the second square mass block and the four corners of another support frame 23, respectively, and are symmetrically distributed along the first and second directions, which are perpendicular to each other. The four third connecting beams 43 are connected to the center of the four sides of one support frame 23 and the center of the four sides of another support frame 23, respectively, and are symmetrically distributed along the first and second directions, which are perpendicular to each other. In this embodiment, the first and second directions are respectively... Figure 1 The X-axis and Y-axis directions are shown.

[0051] It should be noted that, in other embodiments of the present invention, the number of first connecting beams 41 may be at least three and an odd number, and they may be centrally symmetrically distributed with the geometric center of the central mass block 21 as the center of symmetry; or, when the number of first connecting beams 41 is two, the two first connecting beams 41 are symmetrically distributed along a first direction or a second direction; or when the number of first connecting beams 41 is an even number of more than four, these first connecting beams 41 are symmetrically distributed along a first direction and a second direction, and the first direction and the second direction are perpendicular; the number of second connecting beams 42 may also be at least three and an odd number, and they may be centrally symmetrically distributed with the geometric center of the fixed mass block 22 as the center of symmetry; or, the number of second connecting beams 42 may be... When there are two second connecting beams 42, the two second connecting beams 42 are symmetrically distributed along the first direction or the second direction; or when the number of second connecting beams 42 is an even number of more than four, these second connecting beams 42 are symmetrically distributed along the first direction and the second direction, and the first direction and the second direction are perpendicular. The number of third connecting beams 43 can also be at least three and an odd number, and they are centrally symmetrically distributed with the geometric center of the support frame 23 as the center of symmetry. Alternatively, when there are two third connecting beams 43, the two third connecting beams 43 are symmetrically distributed along the first direction or the second direction; or when the number of third connecting beams 43 is an even number of more than four, these third connecting beams 43 are symmetrically distributed along the first direction and the second direction, and the first direction and the second direction are perpendicular.

[0052] like Figure 2 and Figure 3 As shown, the piezoresistive multi-range MEMS pressure sensor of this embodiment also includes a substrate 5. The substrate 5 is fixed on a fixed mass block 22, a support frame 23, a first connecting beam 41, a second connecting beam 42, and a third connecting beam 43, and surrounds the pressure groove 20 to form a vacuum cavity. The substrate 5 is spaced apart from the central mass block 21. That is, the fixed mass block 22, the two support frames 23, the four first connecting beams 41, the four second connecting beams 42, and the four third connecting beams 43 are all fixedly connected to the substrate 5, and surround the pressure groove 20 to form a vacuum cavity. Specifically, the substrate 5 is a glass bottom, and the glass bottom is fixedly connected to the fixed mass block 22, the support frame 23, the first connecting beams 41, the second connecting beams 42, and the third connecting beams 43 through anodic bonding. This piezoresistive multi-range MEMS pressure sensor with a vacuum cavity has high detection accuracy. It should be noted that in other embodiments of the present invention, the base 5 may not be provided. In this case, the pressure groove 20 is connected to the outside atmosphere, and the pressure in the pressure groove 20 is the ambient pressure. This type of piezoresistive multi-range MEMS pressure sensor has better structural stability, but it requires compensation for ambient temperature and ambient pressure to ensure accuracy under different ambient pressures and temperatures.

[0053] like Figures 2 to 4As shown, in this embodiment, the pressure groove 20 between the support frame 23 adjacent to the fixed mass block 22 and the fixed mass block 22 is the outer pressure groove 201, and the piezoresistive resistor 12 is directly opposite the outer pressure groove 201. Specifically, the piezoresistive resistor 12 is directly opposite the edge of the outer pressure groove 201, so that the piezoresistive resistor 12 is located at the point of maximum stress on the pressure-bearing diaphragm 11, thereby maximizing the sensitivity of the piezoresistive multi-range MEMS pressure sensor.

[0054] like Figure 4 As shown, the piezoresistive multi-range MEMS pressure sensor in this embodiment also includes four metal PADs 13 and four piezoresistors 12. The four piezoresistors 12 and the four metal PADs 13 are electrically connected to form a Wheatstone bridge, which makes the piezoresistive multi-range MEMS pressure sensor have the advantages of high sensitivity, good temperature self-compensation performance, excellent linearity, low power consumption, good compatibility, easy integration and high reliability.

[0055] This embodiment also provides a fabrication method for the piezoresistive multi-range MEMS pressure sensor described in the above embodiments, including the following steps:

[0056] S1. A first groove 6101, a second groove 6102, and a third groove 6103 are formed on a first silicon substrate 61. From the inside out, the first silicon substrate 61 consists of a central bump 611, a support pillar 612, and a fixing bump 613. There are two support pillars 612. Figure 5 As shown.

[0057] Specifically, S1 includes the following steps:

[0058] S11. Spin-coat photoresist onto the first silicon substrate 61 to form a first photoresist layer;

[0059] S12. Pattern the first photoresist layer to form the first opening region;

[0060] S13. Dry etching of a portion of the silicon in the first silicon substrate 61 corresponding to the first opening area to form a first groove 6101, a second groove 6102 and a third groove 6103. The first silicon substrate 61 consists of a central bump 611, a support pillar 612 and a fixing bump 613 from the inside to the outside. The support pillar 612 surrounds the central bump 611 and is spaced apart from it.

[0061] S14. Remove the first photoresist layer after it has been patterned.

[0062] In this embodiment, the first groove 6101, the second groove 6102, and the third groove 6103 are formed by dry etching. Along the direction from the central protrusion 611 to the fixed protrusion 613, they are sequentially the first groove 6101, the second groove 6102, and the third groove 6103, with sidewalls extending along the thickness direction of the first silicon substrate 61. It should be noted that in other embodiments of the present invention, the number of support pillars 612 is the same as the number of support frames 23 in the aforementioned piezoresistive multi-range MEMS pressure sensor, and the specific number is determined according to actual needs.

[0063] S2. The second silicon substrate 7 with insulating layer 3 is bonded to the first silicon substrate 61, the insulating layer 3 is sandwiched between the first silicon substrate 61 and the second silicon substrate 7, and the second silicon substrate 7 is thinned, as follows. Figure 6 As shown.

[0064] It should be noted that, in this embodiment, the insulating layer 3 is a single-layer silicon dioxide layer, which is an oxide layer formed on the second silicon substrate 7. In other embodiments, the insulating layer 3 may also be a single-layer structure formed of insulating materials such as silicon nitride or aluminum oxide, or a structure of at least two layers formed of insulating materials such as silicon dioxide, silicon nitride, or aluminum oxide, depending on the actual needs.

[0065] S3. A varistor 12 and an electrical connection layer are formed on the second silicon substrate 7, wherein the varistor 12 is directly opposite the third groove 6103, as shown in the figure. Figure 7 As shown.

[0066] Specifically, S3 includes the following steps:

[0067] S31. Spin-coat photoresist onto the second silicon substrate 7 to form a second photoresist layer;

[0068] S32. Pattern the second photoresist layer to form the second opening region;

[0069] S33. Dilute boron ions are introduced into the second opening area to form a varistor 12.

[0070] S34. Remove the patterned second photoresist layer;

[0071] S35. Spin-coat photoresist onto the second silicon substrate 7 to form a third photoresist layer;

[0072] S36. Pattern the third photoresist layer to form the third opening region;

[0073] S37. Concentrated boron ions are introduced into the third opening region to form an electrical connection layer;

[0074] S38. Remove the patterned third photoresist layer.

[0075] In this embodiment, there are four piezoresistors 12. The piezoresistors 12 are positioned directly opposite the third groove 6103, so that the piezoresistors 12 are located at the point of maximum stress on the finally formed pressure-bearing diaphragm 11, thereby maximizing the sensitivity of the finally formed piezoresistive multi-range MEMS pressure sensor.

[0076] S4. Four metal PADs 13 are formed on the side of the second silicon substrate 7 away from the first silicon substrate 61. There are four varistors 12. The four varistors 12 and the four metal PADs 13 are electrically connected through an electrical connection layer to form a Wheatstone bridge. Two of the metal PADs 13 are electrically connected to the two input terminals of the Wheatstone bridge, and the other two metal PADs 13 are electrically connected to the two output terminals of the Wheatstone bridge.

[0077] Specifically, S4 includes the following steps:

[0078] S41. Spin-coat photoresist on the side of the second silicon substrate 7 away from the first silicon substrate 61 to form a fourth photoresist layer;

[0079] S42. Pattern the fourth photoresist layer to form the fourth opening region;

[0080] S43, deposit a metal layer to form metal PAD 13;

[0081] S44. Remove the patterned fourth photoresist layer.

[0082] In this embodiment, the material of the metal PAD 13 is metal, preferably at least one of Al, Ti, Au, Cu, and Pt. The cross-sectional shape of the metal PAD 13 can be circular, square, or other shapes. This embodiment does not impose specific limitations and the specific shape will be determined according to the actual use.

[0083] The four piezoresistors 12 and four metal pads 13 are electrically connected to form a Wheatstone bridge, which gives the final MEMS pressure sensor the following advantages: It amplifies the piezoresistive change signal through differential output, improving the signal-to-noise ratio and providing high sensitivity; it reduces environmental interference by offsetting common-mode temperature drift, providing good temperature self-compensation performance; it compensates for nonlinear errors using stress distribution, resulting in excellent linearity; it supports constant voltage and constant current power supply, making it suitable for portable devices, with low power consumption and good compatibility; it simplifies amplifier circuit design by directly outputting differential signals, making it easy to integrate; and it enhances fault tolerance through redundant design and mechanical stress isolation, resulting in high reliability.

[0084] S5. A connecting groove 6104 is formed on the side of the first silicon substrate 61 away from the insulating layer 3. The connecting groove 6104 communicates with the first groove 6101, the second groove 6102, and the third groove 6103. Two support pillars 612 form two support frames 23. A central bump 611 forms a central mass block 21, and a fixed bump 613 forms a fixed mass block 22. Simultaneously, a first connecting beam 41, a second connecting beam 42, and a third connecting beam 43 are formed at the bottom of the first silicon substrate 61. The two ends of the first connecting beam 41 are connected to the central mass block 21 and the support frame 23, respectively. The two ends of the second connecting beam 42 are connected to the support frame 23 and the fixed mass block 22, respectively. The two ends of the third connecting beam 43 are connected to two adjacent support frames 23, respectively. Figure 8 As shown.

[0085] Specifically, S5 includes the following steps:

[0086] S51. Spin-coat photoresist on the side of the first silicon substrate 61 away from the insulating layer 3 to form a fifth photoresist layer;

[0087] S52. Pattern the fifth photoresist layer to form the fifth opening region;

[0088] S53. Dry etching of a portion of the silicon in the first silicon substrate 61 corresponding to the fifth opening region to form a connecting trench 6104;

[0089] S54. Remove the patterned fifth photoresist layer.

[0090] S6. Remove the insulating layer 3 opposite to the support frame 23, the first groove 6101, the second groove 6102, and the third groove 6103. A pressure-bearing diaphragm 11 is formed on the second silicon substrate 7. An insulating gap is formed between the pressure-bearing diaphragm 11 and the support frame 23. The first groove 6101, the second groove 6102, and the third groove 6103 form a pressure groove 20. Figure 9 As shown.

[0091] Specifically, S6 includes the following steps:

[0092] S61. Spin-coat photoresist onto the first silicon substrate 61 and part of the insulating layer 3 to form a sixth photoresist layer;

[0093] S62. Pattern the sixth photoresist layer to form the sixth opening region;

[0094] S63. Etch the sixth opening area facing the insulating layer 3 to remove the insulating layer 3 facing the support frame 23, the first groove 6101, the second groove 6102 and the third groove 6103, so that an insulating gap is formed between the support frame 23 and the pressure diaphragm 11.

[0095] S64. Remove the patterned sixth photoresist layer.

[0096] S7. On the side of the first silicon substrate 61 opposite to the insulating layer 3, the anode bonding material is glass. At this time, the pressure groove 20 forms a vacuum cavity, such as... Figure 10 As shown.

[0097] The fabrication method of the piezoresistive multi-range MEMS pressure sensor provided in this embodiment is easy to fabricate, and the fabricated piezoresistive multi-range MEMS pressure sensor can realize the force detection function of multiple pressure ranges integrated on a single chip.

[0098] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A piezoresistive multi-range MEMS pressure sensor, characterized in that, include: Pressure-bearing diaphragm; The mass block includes a central mass block and a fixed mass block arranged at intervals. The central mass block is located at the center of the pressure-bearing diaphragm, and the fixed mass block is located at the edge of the pressure-bearing diaphragm. The fixed mass block, the central mass block, and the pressure-bearing diaphragm form a pressure groove. An insulating layer is sandwiched between the pressure-bearing diaphragm and the mass block; A varistor is disposed on the side of the pressure-bearing diaphragm away from the mass block and facing the pressure groove; At least two support frames are located within the pressure groove. Each support frame surrounds and is spaced apart from the central mass block. From the central mass block toward the fixed mass block, at least two support frames are distributed sequentially at intervals. Each support frame faces the pressure-bearing diaphragm and forms an insulating gap with the pressure-bearing diaphragm. The support frame adjacent to the central mass block is connected to the central mass block through a first connecting beam, the support frame adjacent to the fixed mass block is connected to the fixed mass block through a second connecting beam, and two adjacent support frames are connected through a third connecting beam.

2. The piezoresistive multi-range MEMS pressure sensor according to claim 1, characterized in that, The piezoresistive multi-range MEMS pressure sensor also includes a substrate, which is fixed on the fixed mass block, the support frame, the first connecting beam, the second connecting beam and the third connecting beam and surrounds the pressure groove to form a vacuum cavity. The substrate and the central mass block are spaced apart.

3. The piezoresistive multi-range MEMS pressure sensor according to claim 1, characterized in that, The number of the first connecting beams is at least two and is an even number, and they are symmetrically distributed along the first and second perpendicular directions; or, the number of the first connecting beams is at least three and is an odd number, and they are centrally symmetrically distributed with the geometric center of the central mass block as the center of symmetry. The number of the second connecting beams is at least two and is an even number, and they are symmetrically distributed along the first and second perpendicular directions; or, the number of the second connecting beams is at least three and is an odd number, and they are centrally symmetrically distributed with the geometric center of the central mass block as the center of symmetry. The number of the third connecting beams is at least two and an even number, and they are symmetrically distributed along the first and second perpendicular directions; or, at least two of the support frames have the same shape, the number of the third connecting beams is at least three and an odd number, and they are centrally symmetrically distributed with the geometric center of the support frame as the center of symmetry.

4. The piezoresistive multi-range MEMS pressure sensor according to claim 1, characterized in that, The first connecting beam, the second connecting beam, and the third connecting beam are all straight beams.

5. The piezoresistive multi-range MEMS pressure sensor according to claim 1, characterized in that, The geometric centers of at least two of the support frames coincide with the geometric center of the central mass block, and each of the support frames is a closed frame connected end to end.

6. The piezoresistive multi-range MEMS pressure sensor according to claim 1, characterized in that, The pressure groove between the support frame adjacent to the fixed mass block and the fixed mass block is the outer pressure groove, and the pressure-sensitive resistor is directly opposite the outer pressure groove.

7. The piezoresistive multi-range MEMS pressure sensor according to claim 1, characterized in that, The piezoresistive multi-range MEMS pressure sensor also includes four metal PADs. The number of piezoresistors is four, and the four piezoresistors and the four metal PADs are electrically connected to form a Wheatstone bridge.

8. A method for fabricating a piezoresistive multi-range MEMS pressure sensor according to any one of claims 1-7, characterized in that, include: A first groove, a second groove, and a third groove are formed on a first silicon substrate. The first silicon substrate consists of a central bump, a support pillar, and a fixing bump, arranged from the inside out. The number of support pillars is at least two. A second silicon substrate with an insulating layer is fixed on the first silicon substrate, and the insulating layer is sandwiched between the first silicon substrate and the second silicon substrate; A varistor is formed on the second silicon substrate; A connecting groove is formed on the side of the first silicon substrate away from the insulating layer. The connecting groove communicates with the first groove, the second groove, and the third groove. The support pillar forms a support frame. The central bump forms a central mass block. The fixed bump forms a fixed mass block. At the same time, a first connecting beam, a second connecting beam, and a third connecting beam are formed at the bottom of the first silicon substrate. The two ends of the first connecting beam are respectively connected to the central mass block and the support frame. The two ends of the second connecting beam are respectively connected to the support frame and the fixed mass block. The two ends of the third connecting beam are respectively connected to the two adjacent support frames. The insulating layer opposite the support frame, the first groove, the second groove, and the third groove is removed, and a pressure-bearing diaphragm is formed on the second silicon substrate. An insulating gap is formed between the pressure-bearing diaphragm and the support frame, and the first groove, the second groove, and the third groove form a pressure groove.

9. The fabrication method of the piezoresistive multi-range MEMS pressure sensor according to claim 8, characterized in that, Four metal PADs are formed on the side of the second silicon substrate away from the first silicon substrate. There are four varistors, and the four varistors are electrically connected to the four metal PADs to form a Wheatstone bridge.

10. The fabrication method of the piezoresistive multi-range MEMS pressure sensor according to claim 8, characterized in that, A substrate is fixed on the side of the first silicon substrate away from the insulating layer, and the pressure groove forms a vacuum cavity.

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