A single-chip composite sensor structure and its preparation method

Abstract

The present invention provides a single-chip composite sensor structure and a method for preparing the same. The single-chip composite sensor structure comprises: a single-crystal silicon substrate, an insulating layer on the single-crystal silicon substrate, and an angular velocity sensor, an acceleration sensor, and a pressure sensor integrated on the same surface of the single-crystal silicon substrate. The single-crystal silicon substrate is provided with a plurality of insulating anchor points, and the angular velocity sensor is integrated on the single-crystal silicon substrate via the insulating anchor points. The acceleration sensor and the pressure sensor are insulated from the angular velocity sensor. The angular velocity sensor in the single-chip composite sensor structure of the present invention uses an out-of-plane (Z-axis) electrostatic comb drive in-plane differential capacitance detection method to detect X-axis (or Y-axis) angular velocity. Outer-layer insulating single-crystal silicon pillars serve as anchor points to support a movable electrode and a fixed electrode, respectively, suspended on the single-crystal silicon substrate, thereby resolving the problem of electrical insulation between different electrodes during single-sided sensor processing.

Description

Technical Field

[0001] The present invention relates to the field of silicon micromechanical sensor manufacturing, and in particular to a single-chip composite sensor structure and a preparation method thereof. Background Art

[0002] In recent years, humanity has fully entered the intelligent information age, and the demand for information measurement and control has become increasingly demanding. With the continuous advancement of MEMS (Micro-Electro-Mechanical System, also known as micro-electromechanical system, microsystem, micromachine, etc., which refers to high-tech devices measuring a few millimeters or smaller) technology, multi-axis sensors, miniaturization, high performance, low cost, and mass manufacturing capabilities compatible with IC foundries have become a key trend in the sensing application market. In particular, the recent rise of AR / VR, smart cars, the Internet of Things, robotics, and smart factories has led to widespread dependence on and huge market demand for multi-axis sensors. As a major consumer of MEMS sensors, my country has made significant progress in MEMS sensor design and manufacturing over the past decade. However, approximately 70% of the sensor market is still dominated by foreign MEMS companies. The majority of multi-axis sensors integrated on a single silicon chip are imported from foreign manufacturers (such as Bosch, InvenSense, and STMicroelectronics). Therefore, the integration of multi-axis sensors on a single chip has become a hot topic of research.

[0003] Currently, there are several main methods for integrating multi-axis sensors on a single chip: (1) The 6-axis (3-axis acceleration + 3-axis angular velocity) sensor produced by Fairchild Semiconductor is a representative example, which uses double-sided silicon micromachining technology to integrate multi-axis sensors. Since this sensor requires double-sided alignment lithography, silicon wafer thinning, and bonding processes, the manufacturing process is complex and the manufacturing process is not compatible with IC Foundry processes for mass production. (2) In 1997, T. Juneau et al. at the University of Berkeley developed a 2-axis (X-axis and Y-axis) angular velocity sensor, which uses surface bulk silicon micromachining technology to integrate multi-axis sensors [T. Juneau, AP Pisano, and JH Smith, "Dual axis operation of a micromachined rate gyroscope," in Proceedings of International Solid State Sensors and Actuators Conference (Transducers'97), 1997, vol. 2, pp. 883-886 vol. 2.]. Although traditional surface micromachining sensors achieve small size, low cost, and IC Foundry-compatible processes, they also have obvious shortcomings: a. The thickness of the sensitive structural layer is limited by the LPCVD deposition of polysilicon process (generally ≤5μm), resulting in high mechanical noise and low signal-to-noise ratio in the sensor; b. When the thickness of the structural layer is limited, the capacitor gap is restricted by the process, and there is limited room for sensitivity improvement. (3) In 2015, V.A. Wang from Stanford University in the United States also used SOI silicon wafers through Deep-RIE and vapor-phase HF etching, combined with Epi-seal technology to develop a 4-axis (pressure + 3-axis acceleration) sensor as a representative. He used single-sided silicon micromachining technology to integrate multi-axis sensors on SOI [V.A. Hong et al., "Capacitive sensor fusion: Co-fabricated X / Y and Z-axis accelerometers, pressure sensor, thermometer," in 2015 Transducers-2015 18th International Conference on Solid-State Sensors, Actuators and Microsystems (TRANSDUCERS), 2015, pp. 295-298.].This multi-axis sensor structure is manufactured using SOI silicon wafers and polysilicon technology, and the manufacturing process is compatible with standard IC semiconductor processes. However, they have the following shortcomings: a. The mechanical properties of polysilicon are far inferior to those of single-crystalline silicon, which has a certain impact on the performance characteristics of the sensor; b. SOI silicon wafers are expensive, so the production cost is difficult to further reduce. (4) In 2012, Wang Jiachou et al. from the Shanghai Institute of Microsystem and Information Technology of the Chinese Academy of Sciences developed the first generation of pressure and acceleration composite sensors on ordinary silicon wafers [JC Wang, XY Xia, and XX Li, "Monolithic Integration of Pressure Plus Acceleration Composite TPMS Sensors With a Single-Sided Micromachining Technology," (in English), Journal of Microelectromechanical Systems, vol. 21, no. 2, pp. 284-293, Apr 2012.]. The entire process is carried out on one side of the silicon wafer, and the other side of the silicon wafer does not participate in any process. Therefore, while ensuring the high performance of the sensor, the process cost is greatly reduced, the chip size is reduced, and the preparation process is compatible with the standard semiconductor process of IC Foundry. However, the structure of the 3D bulk silicon microstructure within the prepared silicon substrate is relatively simple, not universal, and no specific design technology and process specifications have been formed, which makes it impossible to realize the single-chip, single-sided integrated preparation of multi-axis composite sensors.

[0004] In summary, the difficulties in integrating multi-axis composite sensors on a single chip and on a single side are mainly as follows: (1) There are multiple electrical signals between different sensors, and each electrical signal needs to be physically isolated. Without the natural isolation layer of SOI silicon wafers and the back isolation process steps of double-sided processing, it is difficult to achieve this goal only on the front side of ordinary silicon wafers; (2) The morphology of different sensors is also very different. Each sensor has a different thickness and a multi-layer structure. Without the back "helping engraving" of the double-sided processing technology, how to release different thicknesses and multi-layer structures on a single side is also worth considering; (3) During the process, the manufacturing process of the sensor will damage the existing structures of other sensors. Therefore, protecting the existing structures and coordinating the process conflicts between sensors are also bottleneck technologies that need to be overcome at present.

[0005] Therefore, how to solve the problem of single-sided collaborative design of different functional sensor structures on a single silicon wafer and the problem of compatible processing of complex three-dimensional sensitive structures with different functions and different levels has become one of the urgent problems to be solved by technical personnel in this field. Summary of the Invention

[0006] In view of the shortcomings of the prior art described above, the purpose of the present invention is to provide a single-chip composite sensor structure and a preparation method thereof, which are used to solve the problems of single-chip single-sided collaborative design between different functional sensor structures in the prior art and the problem of compatible processing of complex three-dimensional sensitive structures with different functions and different levels.

[0007] To achieve the above-mentioned and other related purposes, the present invention provides a single-chip composite sensor structure, comprising: a single-crystal silicon substrate, an insulating layer on the single-crystal silicon substrate, and an angular velocity sensor, an acceleration sensor, and a pressure sensor integrated on the same surface of the single-crystal silicon substrate; wherein, a plurality of insulating anchor points are inserted on the single-crystal silicon substrate, and the angular velocity sensor is integrated on the single-crystal silicon substrate via the insulating anchor points; and the acceleration sensor and the pressure sensor are insulated from the angular velocity sensor.

[0008] Optionally, the angular velocity sensor includes an external support frame, a middle support frame, a vertical torsion beam, an internal support frame, a sensitive beam, a first drive comb group and a second drive comb group; the external support frame is supported on the single crystal silicon substrate through the insulating anchor point, and the external support frame is also provided with a plurality of lead holes; one end of the vertical torsion beam is fixed to the single crystal silicon substrate through the insulating anchor point, and the other end is connected to the outer side wall of the middle support frame; the internal support frame is connected to the middle support frame through the sensitive beam; the first drive comb group includes a first drive comb group provided on the outer side of the middle support frame a movable electrode and a first fixed electrode arranged on the inner side of the external support frame, the projections of the first movable electrode and the first fixed electrode on the single crystal silicon substrate are arranged in a staggered manner, and the first movable electrode and the first fixed electrode have a height difference; the second drive comb group includes a second movable electrode arranged on the inner side of the internal support frame and two second fixed electrodes arranged on the single crystal silicon substrate, the projections of the second movable electrode and the two second fixed electrodes on the single crystal silicon substrate are arranged in a staggered manner; wherein, the second fixed electrode is fixed to the single crystal silicon substrate through the insulating anchor point.

[0009] More optionally, the two second fixed electrodes are arranged along the crystal direction <110> arrangement.

[0010] Optionally, the acceleration sensor includes: a mass block, a first cantilever beam, a second cantilever beam, a groove, a first sensitive resistor, a second sensitive resistor, a first reference resistor and a second reference resistor; the groove is opened in the single crystal silicon substrate, the mass block is arranged in the groove, and one side of the mass block is connected to the single crystal silicon substrate through the first cantilever beam and the second cantilever beam; the first sensitive resistor is arranged on the first cantilever beam and the single crystal silicon substrate; the second sensitive resistor is arranged on the second cantilever beam and the single crystal silicon substrate; the first end of the first reference resistor is connected to the first end of the first sensitive resistor, and the second end is connected to the first end of the second sensitive resistor; the first end of the second reference resistor is connected to the second end of the second sensitive resistor, and the second end is connected to the first end of the first sensitive resistor; wherein the depth of the groove is greater than the thickness of the mass block; an insulating layer is arranged between the first sensitive resistor, the second sensitive resistor, the first reference resistor and the second reference resistor and the single crystal silicon substrate.

[0011] More optionally, the first cantilever beam and the second cantilever beam are arranged along the crystal direction. <211> arrangement.

[0012] Optionally, the pressure sensor includes a pressure film, a reference pressure cavity, a third sensitive resistor, a fourth sensitive resistor, a fifth sensitive resistor and a sixth sensitive resistor; a release hole group is provided on the pressure film, and the pressure film is provided above the reference pressure cavity; the third sensitive resistor is provided on the first side of the pressure film, the fourth sensitive resistor is provided on the second side of the pressure film, and the first side is arranged opposite to the second side; the fifth sensitive resistor is provided on the third side of the pressure film, and the sixth sensitive resistor is provided on the fourth side of the pressure film, and the third side is arranged opposite to the fourth side; the first end of the third sensitive resistor is connected to the first end of the fifth sensitive resistor, and the second end is connected to the first end of the sixth sensitive resistor; the first end of the fourth sensitive resistor is connected to the second end of the fifth sensitive resistor, and the second end is connected to the second end of the sixth sensitive resistor; wherein, an insulating layer is provided between the third sensitive resistor, the fourth sensitive resistor, the fifth sensitive resistor and the sixth sensitive resistor and the single crystal silicon substrate.

[0013] More optionally, the release hole group is along the crystal direction <211> arrangement.

[0014] To achieve the above-mentioned and other related objectives, the present invention further provides a method for preparing a single-chip composite sensor structure, comprising the following steps:

[0015] S1: providing a single crystal silicon substrate, and forming the insulating anchor point in the single crystal silicon substrate;

[0016] S2: forming the insulating layer on the upper surface of the structure obtained in step S1, and preparing the angular velocity sensor, the acceleration sensor, and the pressure sensor;

[0017] Wherein, the angular velocity sensor is supported on the single crystal silicon substrate through the insulating anchor point.

[0018] Optionally, step S1 includes, S11: generating a first silicon oxide layer on the upper surface of the single crystal silicon substrate; S12: etching the first silicon oxide layer and the single crystal silicon substrate to form a deep groove of an annular structure; S13: generating a second silicon oxide layer on the bottom and sidewall of the deep groove; S14: depositing a first silicon nitride layer on the surface of the second silicon oxide layer; S15: filling the first polysilicon in the groove formed by the first silicon nitride layer to form the insulating anchor point.

[0019] Optionally, step S2 includes the following steps:

[0020] S3: forming sensitive resistors of the acceleration sensor and the pressure sensor in the single crystal silicon substrate, and forming a group of release holes in the insulating layer and the single crystal silicon substrate;

[0021] S4: forming a pressure film and a reference pressure cavity of the pressure sensor in the single crystal silicon substrate, and forming lead holes on the insulating layer;

[0022] S5: forming a fixed electrode in the angular velocity sensor in the insulating layer and the single crystal silicon substrate;

[0023] S6: forming a cantilever beam of the acceleration sensor in the single crystal silicon substrate;

[0024] S7: forming a movable electrode, a support frame, a sensitive beam, and a vertical torsion beam of the angular velocity sensor, and a mass block of the acceleration sensor in the single crystal silicon substrate;

[0025] S8: Sputtering metal on the front side of the silicon wafer to prepare leads of the pressure sensor and the acceleration sensor, completing the entire chip process preparation.

[0026] More optionally, in step S3, the insulating layer in the area where the sensitive resistor is located is first removed, and the sensitive resistor is prepared by boron ion implantation; then a first passivation layer is deposited on the single crystal silicon substrate, and the first passivation layer, the insulating layer and the single crystal silicon substrate are etched to obtain the release hole group of the pressure sensor.

[0027] More optionally, in step S4, a second passivation layer is deposited on the side walls of the release hole group, and then a sacrificial gap is etched in the single crystal silicon substrate; the single crystal silicon substrate below the release hole group is selectively corroded to form the pressure film and the reference pressure cavity; a second polysilicon is filled in the release hole group to sew the release hole group; a third passivation layer and a second silicon nitride layer are sequentially deposited on the single crystal silicon substrate, and the second silicon nitride layer and the third passivation layer above the sensitive resistor are removed to prepare a lead hole.

[0028] More optionally, step S4 further includes: after stitching the release hole groups, thinning the third passivation layer to eliminate the process etching margin in step S3.

[0029] More optionally, in step S5, a fourth passivation layer and a third silicon nitride layer are sequentially deposited on the single crystal silicon substrate, and part of the insulating layer, silicon nitride layer and passivation layer in the angular velocity sensor region are etched away to form a fixed electrode in the angular velocity sensor.

[0030] More optionally, in step S6, a fifth passivation layer is deposited on the single crystal silicon substrate, and the single crystal silicon substrate is etched to form a release groove for the cantilever beam of the acceleration sensor; a sixth passivation layer is deposited on the sidewall of the release groove, and then a groove of a first preset depth is etched in the single crystal silicon substrate; and the cantilever beam of the acceleration sensor is selectively etched; wherein the first preset depth is greater than the thickness of the mass block.

[0031] More optionally, in step S7,

[0032] S71: Patterning a passivation layer, silicon nitride, and insulating layer on the single crystal silicon substrate to obtain a pattern of the mass of the acceleration sensor and patterns of the moving electrode, support frame, sensitive beam, and vertical torsion beam of the angular velocity sensor;

[0033] S72: etching the single crystal silicon substrate to obtain a fixed electrode of the angular velocity sensor at a first height;

[0034] S73: Continue etching the single crystal silicon substrate to obtain the fixed electrode, support frame, sensitive beam, and vertical yaw beam structures of the angular velocity sensor, and the mass structure of the acceleration sensor, with the etching depth being a second preset depth. At this time, the depth of the fixed electrode in the driving comb group of the angular velocity sensor is the sum of the first height and the second preset depth, and the thickness of the mass is the second preset depth.

[0035] S74: depositing a seventh passivation layer on the sidewalls of the fixed electrode, the support frame, the sensitive beam, the vertical torsion beam, and the proof mass, and etching the single crystal silicon substrate to form a sacrificial gap of a third preset depth, wherein the third preset depth is greater than or equal to the second preset depth;

[0036] S75: Selectively etching the single crystal silicon substrate to obtain the comb teeth group of the angular velocity sensor, the mass block of the acceleration sensor, and a sacrificial gap below the comb teeth group and the mass block;

[0037] S76: etching away the seventh passivation layer to expose the single crystal silicon layer above the fixed electrode of the angular velocity sensor;

[0038] S77: Etching the fixed electrode to a depth less than the second preset depth, thereby forming a staggered tooth structure of the acceleration sensor in a direction perpendicular to the substrate.

[0039] As described above, the single-chip composite sensor structure and the preparation method thereof of the present invention have the following beneficial effects:

[0040] 1. The angular velocity sensor in the single-chip composite sensor structure of the present invention adopts an out-of-plane (Z-axis) electrostatic comb drive in-plane differential capacitance detection method to realize X-axis (or Y-axis) angular velocity detection; the outer insulating single-crystal silicon pillars serve as anchor points to support the movable electrode and the fixed electrode suspended on the single-crystal silicon substrate, solving the problem of electrical insulation between different electrodes in the single-sided processing of the sensor.

[0041] 2. All structural units of each sensor in the single-chip composite sensor structure of the present invention are processed only through the front side of the silicon wafer, and the back side of the silicon wafer does not participate in any process production. A multi-level complex three-dimensional structure including the pressure film of the pressure sensor, the cantilever beam and mass block of the Z-axis acceleration sensor, and the Z-axis electrostatic drive comb teeth of the angular velocity sensor staggered along the Z direction are cleverly prepared, solving the problem of single-sided integrated processing of a single silicon wafer for multi-axis composite sensor chips with different functions, different thicknesses and complex morphology sensitive structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 Shown is a schematic diagram of the structure of a single-chip composite sensor of the present invention.

[0043] Figure 2 Shown is a top-down schematic diagram of an angular velocity sensor.

[0044] Figure 3 Display as Figure 2 Schematic diagram of the cross-section structure along the C-C' direction.

[0045] Figure 4 Shown is a schematic diagram of the back structure in which the angular velocity sensor is hidden behind a single-crystal silicon substrate.

[0046] Figure 5 Shown is a schematic top view of an accelerometer.

[0047] Figure 6 Display as Figure 5 Enlarged view of point A in the middle.

[0048] Figure 7 Shown is a schematic diagram of the cross-sectional structure of an acceleration sensor.

[0049] Figure 8 Shown is a schematic top view of a pressure sensor.

[0050] Figure 9 Shown is a schematic cross-section of a pressure sensor.

[0051] Figure 10 Schematic diagram showing the deep groove structure etched with a ring anchor point.

[0052] Figure 11 Shown is a schematic diagram of the structure for filling the annular groove to form an insulating anchor point.

[0053] Figure 12 Shown is a schematic diagram of the structure of the anchor insulation cover.

[0054] Figure 13 Shown is a schematic diagram of the detection resistor structure prepared by boron ion implantation.

[0055] Figure 14 Shown is a schematic diagram of the release hole structure etched into the pressure sensor.

[0056] Figure 15 It shows a schematic diagram of protecting the sidewall of the release hole and engraving a sacrificial gap structure at the same time.

[0057] Figure 16 Shown is a schematic diagram of the cavity structure of the corrosion relief pressure sensor.

[0058] Figure 17 Shown is a schematic diagram of the polysilicon annealing stitching release hole structure.

[0059] Figure 18 Shown is a schematic diagram of the structure of the surface passivation layer thinned by RIE etching.

[0060] Figure 19 Shown is a schematic diagram of the structure for preparing pre-lead holes.

[0061] Figure 20 Schematic diagram showing the passivation layer structure of the fixed electrode of the vertical comb teeth of the angular velocity sensor by etching and thinning.

[0062] Figure 21Shown is a schematic diagram of the cantilever beam structure for preparing an acceleration sensor.

[0063] Figure 22 A schematic diagram showing the basic structure of an acceleration sensor and an angular velocity sensor defined by a graphic passivation layer.

[0064] Figure 23 Shown is a schematic diagram of the structure of fixing the electrode height d1 in the etched angular velocity sensor drive comb.

[0065] Figure 24 Shown is a schematic diagram of the structure of etching the height d2 of the angular velocity sensor and the acceleration sensor.

[0066] Figure 25 It shows a schematic diagram of the structure for protecting the sidewall of the release hole and engraving a sacrificial gap d3 at the same time.

[0067] Figure 26 Shown is a schematic diagram of the structure of the corrosion release acceleration and angular velocity sensor.

[0068] Figure 27 Schematic diagram showing the structure of the fixed comb tooth d4 in the etching of the excess passivation layer and the thinning of the driving comb teeth by Deep-RIE.

[0069] Figure 28 Shown is a schematic diagram of the metal lead structure.

[0070] Figure 29 A schematic diagram showing the structure of the support beam used to support the accelerometer mass is shown with the support beam cut out.

[0071] Component number description

[0072] 1 Single crystal silicon substrate

[0073] 2 Angular velocity sensor

[0074] 21, 22, 23 Internal, middle, and external support frames

[0075] 221 Insulated Anchor Point

[0076] 231 lead hole

[0077] 24 Vertical torsion beam

[0078] 25 Sensitive Beam

[0079] 26 Second drive comb group

[0080] 27 First drive comb group

[0081] 271, 261 First and second fixed electrodes

[0082] 272, 262 First and second moving electrodes

[0083] 3 Accelerometer

[0084] 31 mass block

[0085] 32, 33 First and second cantilever beams

[0086] 34 grooves

[0087] 35, 36, 43, 44, 45, 46 First, second, third, fourth, fifth, sixth sensitive resistors

[0088] 37, 38 First and second reference resistors

[0089] 39 Release slot

[0090] 4 Pressure sensor

[0091] 41 Pressure Film

[0092] 411 Release Hole Group

[0093] 42 Reference pressure chamber

[0094] Steps S1 to S8

[0095] L1, L2, L3 transverse lines

[0096] L11, L23 first and second silicon oxide layers

[0097] L12 deep groove

[0098] L21, L102, L112 first, second, and third silicon nitride layers

[0099] L22 First polysilicon

[0100] L42 insulation layer

[0101] L41 Boron Ion

[0102] L51, L101, L111, L121 first, third, fourth, fifth passivation layer

[0103] L52 release hole group

[0104] L61, L151 sacrificial clearance

[0105] L71 reference pressure chamber

[0106] L103 lead hole

[0107] L113 Second fixed electrode

[0108] L122 groove

[0109] L201 lead DETAILED DESCRIPTION

[0110] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0111] See also Figures 1 to 29 It should be noted that the diagrams provided in this embodiment are only used to schematically illustrate the basic concept of the present invention. Therefore, the diagrams only show components related to the present invention and are not drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component can be changed at will, and the component layout type may also be more complicated.

[0112] Example 1

[0113] like Figure 1 As shown, this embodiment provides a single-chip composite sensor structure, comprising: a single-crystalline silicon substrate 1, an insulating layer on the single-crystalline silicon substrate 1, and an angular velocity sensor 2, an acceleration sensor 3, and a pressure sensor 4 integrated on the same surface of the single-crystalline silicon substrate 1. The single-crystalline silicon substrate 1 is provided with a plurality of insulating anchor points 221, and the angular velocity sensor 2 is integrated on the single-crystalline silicon substrate 1 via the insulating anchor points 221. The acceleration sensor 3 and the pressure sensor 4 are insulated from the angular velocity sensor 2. It should be noted that the provision of the insulating layer insulates the angular velocity sensor 2 from the acceleration sensor 3 and from the pressure sensor 4, thereby resolving the problem of electrical insulation between different electrodes in single-sided sensor processing.

[0114] like Figure 2 As shown, the angular velocity sensor 2 includes: the angular velocity sensor includes an outer supporting frame 23, a middle supporting frame 22, a vertical torsion beam 24, an inner supporting frame 21, a sensitive beam 25, a first driving comb tooth group 27 and a second driving comb tooth group 26.

[0115] Specifically, the external support frame 23 is supported on the single crystal silicon substrate 1 through an insulating anchor point 221, and a plurality of lead holes 231 are also provided on the external support frame 23; one end of the vertical torsion beam 24 is fixed on the single crystal silicon substrate 1 through an insulating anchor point 221, and the other end is connected to the outer wall of the middle support frame 22; the first drive comb group 27 includes a first movable electrode 272 arranged on the outside of the middle support frame 22 and a first fixed electrode 271 arranged on the inside of the external support frame 23, the projections of the first movable electrode 272 and the first fixed electrode 271 on the single crystal silicon substrate 1 are arranged in a staggered manner, and the first movable electrode 272 and the first fixed electrode 271 have a height difference.

[0116] As an example, Figure 2 As shown, the external support frame 23 is supported on the single crystal silicon substrate 1 by the four insulating anchor points 221, and the four insulating anchor points 221 are respectively arranged at the four corners of the external support frame 23. In this embodiment, the insulating anchor points 221 are columnar single crystal silicon anchor points, and other connection structures are also applicable to the present invention and are not limited here. It should be noted that the insulating anchor points 221 in this embodiment are arranged at the four corners of the external support frame 23 to connect the four borders of the external support frame 23; in actual use, the setting position of the insulating anchor points 221 is not limited. In which, when in use, the external support frame 23 is connected to AC plus DC excitation, and the middle support frame 22 is grounded. The angular velocity sensor 2 of the present invention, by setting the first movable electrode 272 and the first fixed electrode 271 of the tooth structure, and the first movable electrode 272 and the first fixed electrode 271 have a height difference, can provide electrostatic drive of the out-of-plane Z axis (perpendicular to the direction of the single crystal silicon substrate 1). As Figure 3 for Figure 2 In the cross-sectional view along the C-C' direction, it can be clearly seen that there is a height difference between the first movable electrode 272 and the first fixed electrode 271. It should be noted that the projection of the first movable electrode 272 on the single crystal silicon substrate 1 surrounds the projection of the first fixed electrode 271 on the single crystal silicon substrate 1, and there is a gap between the projection of the first movable electrode 272 on the single crystal silicon substrate 1 and the projection of the first fixed electrode 271 on the single crystal silicon substrate 1, thereby providing space for the movement of the first movable electrode 272. As an example, the vertical torsion beams 24 in this embodiment are provided in four numbers, which are respectively provided on the four sides of the middle support frame 22; in actual production, two may also be provided on opposite sides of the middle support frame 22, and the present embodiment is not limited thereto.

[0117] Specifically, the second driving comb group 26 includes a second movable electrode 262 provided on the inner side of the internal support frame 21 and two second fixed electrodes 261 provided on the single crystal silicon substrate 1. The projections of the second movable electrode 262 and the two second fixed electrodes 262 on the single crystal silicon substrate 1 are arranged in a staggered manner. The internal support frame 21 is connected to the middle support frame 22 via the sensitive beam 25. The second fixed electrodes 261 are fixed to the single crystal silicon substrate 1 via the insulating anchor point 221. Figure 2 As shown, the angular velocity sensor 2 in this embodiment can measure the Y axis (crystal direction) by connecting a differential amplifier circuit between the two second fixed electrodes 261. <110> direction) or X-axis (crystal direction <211> It should be noted that in this embodiment, the Z axis, <110> direction, <211> As an example, the number of the sensitive beams 25 is 4, which are arranged in the crystal direction <211> In actual production, the number and location of the sensitive beams 25 may also vary, such as setting two, respectively arranged in the crystal direction. <211> on both sides, not limited to this embodiment.

[0118] As an example, the two second fixed electrodes 261 are arranged along the crystal direction. <110> In the production process, the two second fixed electrodes 261 may also be arranged along the crystal direction <211> The arrangement is not limited here. Figure 4 This is a schematic diagram of the back structure of the angular velocity sensor 2 hidden behind the single crystal silicon substrate 1. It can be clearly seen that the angular velocity sensor 2 of this embodiment is suspended on the single crystal silicon substrate 1 through the insulating anchor point 221, solving the problem of electrical insulation between different electrodes in the single-sided processing of the sensor.

[0119] like Figure 5 As shown, the acceleration sensor 3 includes: a mass block 31, a first cantilever beam 32, a second cantilever beam 33, a groove 34 (in Figure 7 ), a first sensitive resistor 35, a second sensitive resistor 36, a first reference resistor 37 and a second reference resistor 38.

[0120] Specifically, if Figure 7As shown, the groove 34 is defined within the single crystal silicon substrate 1, and the mass block 31 is disposed within the groove 34. One side of the mass block 31 is connected to the single crystal silicon substrate 1 via the first cantilever beam 32 and the second cantilever beam 33. The first sensitive resistor 35 is disposed on the first cantilever beam 32 and the single crystal silicon substrate 1, i.e., the first sensitive resistor 35 is placed at the point of maximum stress on the first cantilever beam 32. The second sensitive resistor 36 is disposed on the second cantilever beam 33 and the single crystal silicon substrate 1, i.e., the second sensitive resistor 36 is placed at the point of maximum stress on the second cantilever beam 33. The first end of the first reference resistor 37 is connected to the first end of the first sensitive resistor 35, and the second end is connected to the first end of the second sensitive resistor 36; the first end of the second reference resistor 38 is connected to the second end of the second sensitive resistor 36, and the second end is connected to the first end of the first sensitive resistor 35; wherein the depth of the groove 34 is greater than the thickness of the mass block 31, thereby providing space for the mass block 31 to move; an insulating layer is provided between the first sensitive resistor 35, the second sensitive resistor 36, the first reference resistor 37 and the second reference resistor 38 and the single crystal silicon substrate 1. Figure 6 The figure shows a schematic structural diagram of the second reference resistor 38. The second reference resistor 38 is an S-shaped resistor bar. The force-sensitive characteristics of the resistor bar are utilized. When the resistor is subjected to force, the resistivity changes. In this embodiment, the first sensitive resistor 35, the second sensitive resistor 36 and the first reference resistor 37 are essentially the same as the second reference resistor 38.

[0121] As an example, the first cantilever beam 32 and the second cantilever beam 33 are arranged along the crystal direction. <211> In the implementation of production, the first cantilever beam 32 and the second cantilever beam 33 may also be along the crystal direction <110> The arrangement is not limited here. Figure 7 Displayed as the acceleration sensor along <211> The cross-sectional view in the direction of the axial direction clearly shows that the mass block 31 is placed in the groove 34. A gap exists between the mass block 31 and the sidewall of the groove 34 to provide space for the movement of the mass block 31. In use, the first end of the first sensitive resistor 35, the second end of the first sensitive resistor 35, the first end of the second sensitive resistor 36, and the second end of the second sensitive resistor 36 are connected to a Wheatstone bridge to form a half-bridge circuit.

[0122] like Figure 8 As shown, the pressure sensor 4 includes a pressure film 41, a reference pressure cavity 42 (such as Figure 9 As shown), a third sensitive resistor 43, a fourth sensitive resistor 44, a fifth sensitive resistor 45 and a sixth sensitive resistor 46.

[0123] Specifically, if Figure 8As shown, the pressure film 41 is provided with a group of release holes 411. The pressure film 41 is provided above the reference pressure chamber 42. The third sensitive resistor 43 is provided on the first side of the pressure film 41, and the fourth sensitive resistor 44 is provided on the second side of the pressure film 41, with the first side and the second side being opposite each other. The fifth sensitive resistor 45 is provided on the third side of the pressure film 41, and the sixth sensitive resistor 46 is provided on the fourth side of the pressure film 41, with the third side and the fourth side being opposite each other. The first end of the third sensitive resistor 43 is connected to the first end of the fifth sensitive resistor 45, and the second end is connected to the first end of the sixth sensitive resistor 46. The first end of the fourth sensitive resistor 44 is connected to the second end of the fifth sensitive resistor 45, and the second end is connected to the second end of the sixth sensitive resistor 46. An insulating layer is provided between the third sensitive resistor 43, the fourth sensitive resistor 44, the fifth sensitive resistor 45, and the sixth sensitive resistor 46 and the single crystal silicon substrate 1.

[0124] As an example, the release hole group 411 is along the crystal direction <211> In the production process, the release hole group 411 can also be arranged along the crystal direction <110> When in use, the first end of the third sensitive resistor 43, the second end of the third sensitive resistor 43, the first end of the fourth sensitive resistor 44 and the second end of the fourth sensitive resistor 44 are connected to a Wheatstone bridge to form a full-bridge circuit.

[0125] The angular velocity sensor in the single-chip composite sensor structure of the present invention adopts an out-of-plane (Z-axis) electrostatic comb drive in-plane differential capacitance detection method to realize X-axis (or Y-axis) angular velocity detection; the outer insulating single-crystal silicon pillars are used as anchor points to support the movable electrode and the fixed electrode to be suspended on the single-crystal silicon substrate, solving the problem of electrical insulation between different electrodes in the single-sided processing of the sensor.

[0126] Example 2

[0127] This embodiment provides a method for preparing a single-chip composite sensor structure, which is used to prepare the single-chip composite sensor structure described in Example 1. The method for preparing the single-chip composite sensor structure includes the following steps:

[0128] S1: providing a single crystal silicon substrate 1 and forming the insulating anchor point 221 in the single crystal silicon substrate 1 .

[0129] Specifically, step S1 includes: Figure 10 As shown, S11: a first silicon oxide layer L11 is generated on the upper surface of the single crystal silicon substrate 1; as an example, the thickness of the single crystal silicon substrate 1 is 450 μm, and a silicon oxide layer L11 is formed on the upper surface of the single crystal silicon substrate 1 by thermal oxidation. Oxide layer (the first silicon oxide layer L11). S12: Etch the first silicon oxide layer L11 and the single crystal silicon substrate 1 to form a deep groove L12 of an annular structure; as an example, the deep groove L12 of the insulating anchor 221 structure is photoetched in the angular velocity sensor area, and the first silicon oxide layer L11 and the single crystal silicon substrate 1 are etched away using reactive ion etching technology (RIE, Reactive Ion Etch) to form a deep groove L12 of an annular structure serving as the insulating anchor 221. The deep groove L12 uses the first silicon oxide layer L11 as a mask, and uses a silicon deep reactive ion etching process (Deep-RIE) to etch out the deep groove L12 of the annular anchor structure with a width of 4 μm and a depth of 80 μm. As shown Figure 11 As shown, S13: a second silicon oxide layer L23 is formed on the bottom surface and sidewalls of the deep trench L12. As an example, a thermal oxidation process is used to grow the second silicon oxide layer L23 to a thickness of 2 μm on the bottom surface and sidewalls of the deep trench L12. S14: a first silicon nitride layer L21 is deposited on the surface of the second silicon oxide layer L23. As an example, a low-stress first silicon nitride layer L21 is deposited to a thickness of 1 μm on the surface of the second silicon oxide layer L23. S15: Filling the first polysilicon L22 in the groove formed by the first silicon nitride layer L21 to form the insulating anchor 221; as an example, filling the groove formed by the first silicon nitride layer L21 with the first polysilicon L22 with a thickness of 2 μm until the deep groove L12 is filled, and then Deep-RIE is used to remove the first silicon oxide layer L11 above the deep groove L12, and RIE is used to remove the surface first silicon nitride layer L21 and the second silicon oxide layer L23 to achieve surface flatness; then, a layer of 2 μm silicon oxide is grown on the single crystal silicon substrate 1 by thermal oxidation, and the silicon oxide outside the single crystal silicon anchor area formed by the deep groove L12 is etched away to produce an insulating structure of the single crystal silicon anchor to form the insulating anchor 221.

[0130] It should be noted that, in this embodiment, Figures 10 to 29 The two dotted lines in the middle divide the section view into three parts. The section view on the far left is Figure 2 The cross-section diagram of the dotted line L1 is shown in the middle. Figure 8 The cross-sectional view of the middle dotted line L3 is shown; the cross-sectional view on the far right is Figure 5 The cross section of the middle dotted line L2 is shown. Figures 10 to 29 Only the preparation cross-sectional views of three sensors are made, and the positions are not limited.

[0131] S2: forming the insulating layer L42 on the upper surface of the structure obtained in step S1, and preparing the angular velocity sensor 2, the acceleration sensor 3, and the pressure sensor 4. The angular velocity sensor 2 is supported on the single crystal silicon substrate 1 by the insulating anchor points 221.

[0132] Specifically, step S2 includes the following steps:

[0133] S3: Sensitive resistors (the first sensitive resistor 35, the second sensitive resistor 36, the third sensitive resistor 43, the third sensitive resistor 43, the fifth sensitive resistor 45 and the sixth sensitive resistor 46) of the acceleration sensor 3 and the pressure sensor 4 are formed in the single crystal silicon substrate 1, and a release hole group L52 is formed in the insulating layer L42 and the single crystal silicon substrate 1.

[0134] Specifically, if Figure 13 As shown, first remove the insulating layer L42 in the area where the sensitive resistor is located, and prepare the sensitive resistor by implanting boron ions L41; as an example, a layer is grown on the single crystal silicon substrate 1 by thermal oxidation. The insulating layer L42 of silicon oxide is used as a barrier layer for the injection of boron ions L41, and then the sensitive resistor areas of the acceleration sensor and the pressure sensor are formed by photolithography. The insulating layer L42 in the area is removed by RIE, and then the sensitive resistor is prepared by ion implantation. Figure 14 As shown, a first passivation layer L51 is then deposited on the single crystal silicon substrate 1, and the first passivation layer L51, the insulating layer L42 and the single crystal silicon substrate 1 are etched to obtain the release hole group L52 of the pressure sensor; as an example, a 1μm TEOS (ethyl silicate) passivation layer L51 (first passivation layer L51) is deposited on the single crystal silicon substrate 1, and the release hole group L52 is etched in the pressure sensor area using silicon deep reactive ion etching technology.

[0135] S4: forming the pressure film 41 and the reference pressure cavity 42 of the pressure sensor 4 in the single crystal silicon substrate 1 , and forming lead holes on the insulating layer L42 .

[0136] Specifically, if Figure 15 As shown, a second passivation layer is deposited on the sidewalls of the release hole group L52, and then a sacrificial gap L61 is etched in the single crystal silicon substrate 1; as an example, a layer of LPCVD is deposited on the sidewalls of the release hole group L52. The TEOS passivation layer (second passivation layer) is used as the sidewall protection layer for the release hole group L52 corrosion. The TEOS passivation layer at the bottom of the release hole group L52 is stripped cleanly by RIE etching (in the actual preparation process, when the passivation layer is deposited on the sidewall of the release hole group L52, the passivation layer will also be deposited on the bottom, so the passivation layer at the bottom must be stripped). Then, Deep-RIE is used to etch out the sacrificial gap L61 of the first preset depth. Figure 16As shown, the single crystal silicon substrate 1 below the release hole group L52 is selectively etched to form the pressure film 41 and the reference pressure cavity 42 (L71). Figure 17 As shown, the second polysilicon L81 is filled in the release hole group L52 to stitch the release hole group L52; as an example, the second polysilicon L81 with low stress of 4 μm is filled in the release hole group L52 to stitch the release hole group L52, and the Deep-RIE process is used to remove the excess polysilicon on the surface of the release hole group L52 to achieve surface flatness. Figure 19 As shown, a third passivation layer L101 and a second silicon nitride layer L102 are sequentially deposited on the single crystal silicon substrate 1, the second silicon nitride layer L102 and the third passivation layer L101 above the sensitive resistor are removed, and a lead hole L103 is prepared; as an example, a layer is deposited on the single crystal silicon substrate 1 TEOS passivation layer L101 (the third passivation layer) is then deposited Silicon nitride L102 (the second silicon nitride L102) is photoetched in the lead hole L103 area, and the silicon nitride, silicon oxide and TEOS passivation layer in the sensitive resistor area are removed to prepare the pre-lead hole L103. As an example, wet etching is performed using a TMAH solution or a KOH solution.

[0137] As an implementation of this embodiment, step S4 further includes: after stitching the release hole group L52, thinning the third passivation layer L101 to eliminate the process etching margin of the first passivation layer L51 deposited in step S3. Figure 18 As shown, the surface passivation layer (the third passivation layer L101) is thinned by RIE etching to This is to eliminate the process etching margin of the first passivation layer L51 deposited in step S3, thereby providing a mask for the first driving comb tooth group.

[0138] S5 : forming a fixed electrode (second fixed electrode 261 ) in the angular velocity sensor 2 in the insulating layer L42 and the single crystal silicon substrate 1 .

[0139] Specifically, if Figure 20 As shown, a fourth passivation layer L111 and a third silicon nitride layer L112 are sequentially deposited on the single crystal silicon substrate 1, and a portion of the insulating layer, silicon nitride layer and passivation layer in the angular velocity sensor 2 region is etched away to form the second fixed electrode L113 (the second fixed electrode 261). As an example, a layer of LPCVD is deposited on the single crystal silicon substrate 1. After the TEOS passivation layer L111 (the fourth passivation layer L111), another layer is deposited Silicon nitride L112 (third silicon nitride layer L112), RIE etches away the silicon oxide, silicon nitride and passivation layer in the area above the second fixed electrode L113 (the second fixed electrode 261) of the angular velocity sensor.

[0140] S6 : forming cantilever beams (a first cantilever beam 32 and a second cantilever beam 33 ) of the acceleration sensor 3 in the single crystal silicon substrate 1 .

[0141] Specifically, if Figure 21 As shown, a fifth passivation layer L121 is deposited on the single crystal silicon substrate 1, and the single crystal silicon substrate 1 is etched to form a release groove 39 (as shown in FIG. Figure 5 As shown); As an example, LPCVD is deposited on the single crystal silicon substrate 1 The TEOS passivation layer L121 (fifth passivation layer L121) is etched using photolithography + RIE + Deep-RIE to form a release groove 39 for the cantilever beam of the acceleration sensor, thereby defining the shape of the cantilever beam of the acceleration sensor 3 and its structural layer thickness. A sixth passivation layer is deposited on the sidewall of the release groove 39, and then a groove L122 of a first preset depth is etched in the single crystal silicon substrate 1; as an example, another layer is deposited on the sidewall of the release groove 39 by LPCVD. A TEOS passivation layer (the sixth passivation layer) is formed to protect the sidewalls of the groove L122. The TEOS passivation layer at the bottom of the groove L122 is stripped cleanly using RIE etching (when the passivation layer is deposited on the sidewalls of the release groove 39, it is also deposited on the bottom of the release groove 39, so the passivation layer at the bottom of the release groove 39 must be stripped). Then, a Deep-RIE process is used to etch a sacrificial gap of a first preset depth. The cantilever beam of the acceleration sensor 3 is then selectively etched. The TMAH solution selectively etches and releases the cantilever beam structure of the acceleration sensor 3 and the sacrificial gap located below it; the first preset depth is greater than the thickness of the mass block.

[0142] S7: forming the movable electrode, the supporting frame, the sensitive beam and the vertical torsion beam of the angular velocity sensor, and the mass block of the acceleration sensor in the single crystal silicon substrate 1.

[0143] Specifically, step S7 includes, S71: patterning the passivation layer, silicon nitride and insulating layer on the single crystal silicon substrate 1 to obtain the mass block pattern of the acceleration sensor 3 and the patterns of the movable electrodes (the first movable electrode 272 and the second movable electrode 262) of the angular velocity sensor 2, the support frame (the outer support frame 23, the middle support frame 22 and the inner support frame 21), the sensitive beam 25 and the vertical torsion beam 24. The photoresist is retained as a subsequent Deep-RIE etching mask. As an example, Figure 22 As shown, the The silicon oxide and silicon nitride composite passivation layer is used to define the pattern of the mass block of the acceleration sensor 3 and the pattern of the moving electrode, support frame, sensitive beam and vertical torsion beam of the angular velocity sensor 2.

[0144] S72: Etching the single crystal silicon substrate 1 to obtain the fixed electrodes of the angular velocity sensor 2 (the first fixed electrode 271 and the second fixed electrode 261) at a first height. Figure 23 As shown, the single crystal silicon substrate 1 is photolithographically processed with a resist to obtain a pattern of the fixed electrode in the angular velocity sensor 2 , and then the fixed electrode of the angular velocity sensor 2 is etched with a first height d1 (12 μm) by Deep-RIE with a resist.

[0145] S73: Continue etching the single crystal silicon substrate 1 to obtain the fixed electrode, support frame, sensitive beam and vertical torsion beam structure of the angular velocity sensor 2 and the mass structure of the acceleration sensor 3, with the etching depth being the second preset depth; at this time, the depth of the fixed electrode in the driving comb group of the angular velocity sensor 2 is the sum of the first height and the second preset depth, and the mass thickness is the second preset depth. As an example, Figure 24 As shown, after stripping, Deep-RIE is continued to etch the exposed structural pattern to define the fixed electrode, support frame, sensitive beam, and vertical yaw beam structures of the angular velocity sensor 2, as well as the mass structure of the acceleration sensor 3. The etching depth is a second predetermined depth d2 (35 μm). At this point, the fixed electrode depth is d1 + d2, and the mass thickness is d2.

[0146] S74: Deposit a seventh passivation layer on the sidewalls of the fixed electrode, support frame, sensitive beam, vertical torsion beam and mass block, and etch the single crystal silicon substrate 1 to form a sacrificial gap L151 of a third preset depth, wherein the third preset depth is greater than or equal to the second preset depth. Figure 25 As shown, a layer of LPCVD is deposited on the side walls of the fixed electrode, support frame, sensitive beam, vertical torsion beam and mass block. The TEOS passivation layer (the seventh passivation layer) is used to protect the sidewalls of the shallow groove. The TEOS passivation layer at the bottom of the shallow groove is stripped cleanly by RIE etching, and then Deep-RIE is used to etch a sacrificial gap L151 of a third preset depth d3, and the etching depth d3≥d2.

[0147] S75: Selectively etch the single crystal silicon substrate 1 to obtain the comb teeth group of the angular velocity sensor 2, the mass block of the acceleration sensor 3, and the sacrificial gap below the comb teeth group and the mass block. Figure 26 As shown, the TMAH solution selectively corrodes and releases the comb teeth group of the angular velocity sensor 2 , the mass block of the acceleration sensor 3 , and the sacrificial gap located therebelow.

[0148] S76: Etch away the seventh passivation layer to expose the single crystal silicon layer above the fixed electrode of the angular velocity sensor 2. As an example, Figure 27 As shown, RIE etching The seventh passivation layer is removed to expose the single crystal silicon layer above the fixed electrode in the angular velocity sensor 2.

[0149] S77: Etching the fixed electrode to a depth less than the second preset depth, forming a staggered tooth structure of the acceleration sensor 3 in a direction perpendicular to the substrate. Figure 27 As shown, the fixed electrode is thinned by Deep-RIE etching, and the etching depth d4 (12 μm) is less than the third preset depth d2, forming a staggered tooth structure of the acceleration sensor in the Z-axis direction.

[0150] S8: Sputtering metal on the front of the silicon wafer to prepare the lead L201 of the pressure sensor 4 and the acceleration sensor 3, completing the entire chip process preparation. Figure 28 As shown, RIE etching The passivation layer is formed until the lead hole is exposed, and then metal AL is sputtered on the front of the silicon wafer. After spraying and photolithography, the aluminum lead L201 (lead L201) is prepared using the ION-BEAM (ion beam sputtering) process. In this embodiment, the lead is aluminum wire; in production, other metal wires such as copper wire, gold wire, etc. can also be used, which is not limited here. Figure 29 As shown, the support beam area for the mass block supporting the acceleration sensor is then photolithographically processed by spraying, and RIE etching is used to The passivation layer is used as a mask to etch away the support beams used to support the mass block of the acceleration sensor, and the entire chip is prepared.

[0151] All structural units of each sensor in the single-chip composite sensor structure of the present invention are processed only through the front side of the silicon wafer, and the back side of the silicon wafer does not participate in any process production. A multi-level complex three-dimensional structure including the pressure diaphragm of the pressure sensor, the cantilever beam and mass block of the Z-axis acceleration sensor, and the Z-axis electrostatic drive comb teeth of the X-axis angular velocity sensor with staggered teeth along the Z direction is cleverly prepared, solving the problem of single-sided integrated processing of a single silicon wafer for multi-axis composite sensor chips with different functions, different thicknesses and complex morphology sensitive structures.

[0152] In summary, the present invention provides a single-chip composite sensor structure and a preparation method thereof. The single-chip composite sensor structure includes: a single-crystal silicon substrate, an insulating layer on the single-crystal silicon substrate, and an angular velocity sensor, an acceleration sensor, and a pressure sensor integrated on the same surface of the single-crystal silicon substrate; wherein a plurality of insulating anchor points are inserted on the single-crystal silicon substrate, and the angular velocity sensor is integrated on the single-crystal silicon substrate through the insulating anchor points; the acceleration sensor and the pressure sensor are insulated from the angular velocity sensor. The angular velocity sensor in the single-chip composite sensor structure of the present invention uses an out-of-plane (Z-axis) electrostatic comb drive and an in-plane differential capacitance detection method to detect the angular velocity of the X-axis (or Y-axis). The outer insulating single-crystal silicon pillars serve as anchor points to support the movable electrode and the fixed electrode, which are suspended on the single-crystal silicon substrate, respectively, solving the problem of electrical insulation between different electrodes in the single-sided processing of the sensor. All structural units of each sensor in the single-chip composite sensor structure of the present invention are processed only on the front side of the silicon wafer, and the back side of the silicon wafer is not involved in any process production. A multi-layered complex three-dimensional structure is cleverly prepared, including the pressure diaphragm of the pressure sensor, the cantilever beam and mass block of the Z-axis acceleration sensor, and the Z-axis electrostatic drive comb teeth staggered along the Z direction of the X-axis angular velocity sensor. This solves the problem of single-sided integrated processing of multi-axis composite sensor chips with different functions, different thicknesses, and complex morphology. Therefore, the present invention effectively overcomes the various shortcomings of the prior art and has high industrial utilization value.

[0153] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A method for preparing a single-chip composite sensor structure, characterized in that: The single-chip composite sensor structure includes: a single-crystal silicon substrate, an insulating layer on the single-crystal silicon substrate, and an angular velocity sensor, an acceleration sensor, and a pressure sensor integrated on the same surface of the single-crystal silicon substrate; wherein a plurality of insulating anchor points are inserted on the single-crystal silicon substrate, and the angular velocity sensor is integrated on the single-crystal silicon substrate via the insulating anchor points; the acceleration sensor and the pressure sensor are insulated from the angular velocity sensor by an insulating layer, wherein the insulating anchor points include a deep trench with an annular structure, a second silicon oxide layer, a first silicon nitride layer, and a first polysilicon layer, wherein the deep trench is located in the single-crystal silicon substrate, the second silicon oxide layer is located on the bottom surface and sidewalls of the deep trench, the first silicon nitride layer is located on the surface of the second silicon oxide layer, and the first polysilicon is filled in the trench formed by the first silicon nitride layer; The method for preparing the single-chip composite sensor structure includes the following steps: S1: providing a single-crystal silicon substrate, and forming the insulating anchor point in the single-crystal silicon substrate, including the following steps: S11: forming a first silicon oxide layer on the upper surface of the single-crystal silicon substrate; S12: etching the first silicon oxide layer and the single-crystal silicon substrate to form the deep groove of the ring structure; S13: forming a second silicon oxide layer on the bottom surface and sidewalls of the deep groove; S14: depositing the first silicon nitride layer on the surface of the second silicon oxide layer; S15: filling the first polysilicon in the groove formed by the first silicon nitride layer to form the insulating anchor point; S2: forming the insulating layer on the upper surface of the structure obtained in step S1; S3: forming sensitive resistors of the acceleration sensor and the pressure sensor in the single crystal silicon substrate, and forming a group of release holes in the insulating layer and the single crystal silicon substrate; S4: forming a pressure film and a reference pressure cavity of the pressure sensor in the single crystal silicon substrate, and forming lead holes on the insulating layer; S5: forming a fixed electrode in the angular velocity sensor in the insulating layer and the single crystal silicon substrate; S6: forming a cantilever beam of the acceleration sensor in the single crystal silicon substrate; S7: forming the moving electrode, support frame, sensitive beam and vertical torsion beam of the angular velocity sensor, and the mass block of the acceleration sensor in the single crystal silicon substrate; in step S7, specifically including S71: patterning the passivation layer, silicon nitride and insulating layer on the single crystal silicon substrate to obtain the mass block pattern of the acceleration sensor and the pattern of the moving electrode, support frame, sensitive beam and vertical torsion beam of the angular velocity sensor; S72: etching the single crystal silicon substrate to obtain the fixed electrode of the angular velocity sensor at a first height; S73: continuing to etch the single crystal silicon substrate to obtain the structure of the fixed electrode, support frame, sensitive beam and vertical torsion beam of the angular velocity sensor and the structure of the mass block of the acceleration sensor, and the etching depth is a second preset depth; at this time, the driving comb group of the angular velocity sensor The depth of the fixed electrode is the sum of the first height and the second preset depth, and the thickness of the mass block is the second preset depth; S74: depositing a seventh passivation layer on the sidewalls of the fixed electrode, the support frame, the sensitive beam, the vertical torsion beam, and the mass block, and etching the single crystal silicon substrate to form a sacrificial gap of a third preset depth, wherein the third preset depth is greater than or equal to the second preset depth; S75: selectively corroding the single crystal silicon substrate to obtain the comb teeth group of the angular velocity sensor, the mass block of the acceleration sensor, and the sacrificial gap below the comb teeth group and the mass block; S76: etching away the seventh passivation layer to expose the single crystal silicon layer above the fixed electrode of the angular velocity sensor; S77: etching the fixed electrode to a depth less than the second preset depth to form a staggered tooth structure of the acceleration sensor in a direction perpendicular to the substrate; S8: Sputtering metal on the front side of the silicon wafer to prepare leads of the pressure sensor and the acceleration sensor, completing the entire chip process preparation.

2. The method for preparing a single-chip composite sensor structure according to claim 1, characterized in that: The angular velocity sensor includes an external support frame, a middle support frame, a vertical torsion beam, an internal support frame, a sensitive beam, a first drive comb group and a second drive comb group; the external support frame is supported on the single crystal silicon substrate through the insulating anchor point, and the external support frame is also provided with a plurality of lead holes; one end of the vertical torsion beam is fixed to the single crystal silicon substrate through the insulating anchor point, and the other end is connected to the outer wall of the middle support frame; the internal support frame is connected to the middle support frame through the sensitive beam; the first drive comb group includes a first A movable electrode and a first fixed electrode arranged on the inner side of the external support frame, the projections of the first movable electrode and the first fixed electrode on the single crystal silicon substrate are arranged in a staggered manner, and the first movable electrode and the first fixed electrode have a height difference; the second drive comb group includes a second movable electrode arranged on the inner side of the internal support frame and two second fixed electrodes arranged on the single crystal silicon substrate, the projections of the second movable electrode and the two second fixed electrodes on the single crystal silicon substrate are arranged in a staggered manner; wherein, the second fixed electrode is fixed to the single crystal silicon substrate through the insulating anchor point.

3. The method for preparing a single-chip composite sensor structure according to claim 2, characterized in that: The two second fixed electrodes are along the crystal direction <110> arrangement.

4. The method for preparing a single-chip composite sensor structure according to claim 1, characterized in that: The acceleration sensor includes: a mass block, a first cantilever beam, a second cantilever beam, a groove, a first sensitive resistor, a second sensitive resistor, a first reference resistor, and a second reference resistor; the groove is opened in the single crystal silicon substrate, the mass block is arranged in the groove, and one side of the mass block is connected to the single crystal silicon substrate through the first cantilever beam and the second cantilever beam; the first sensitive resistor is arranged on the first cantilever beam and the single crystal silicon substrate; the second sensitive resistor is arranged on the second cantilever beam and the single crystal silicon substrate; a first end of the first reference resistor is connected to the first end of the first sensitive resistor, and a second end is connected to the first end of the second sensitive resistor; a first end of the second reference resistor is connected to the second end of the second sensitive resistor, and a second end is connected to the first end of the first sensitive resistor; wherein the depth of the groove is greater than the thickness of the mass block; an insulating layer is arranged between the first sensitive resistor, the second sensitive resistor, the first reference resistor, and the second reference resistor and the single crystal silicon substrate.

5. The method for preparing a single-chip composite sensor structure according to claim 4, characterized in that: The first cantilever beam and the second cantilever beam are arranged along the crystal direction <211> arrangement.

6. The single-chip composite sensor structure according to claim 1, characterized in that: The pressure sensor includes a pressure film, a reference pressure cavity, a third sensitive resistor, a fourth sensitive resistor, a fifth sensitive resistor and a sixth sensitive resistor; a release hole group is provided on the pressure film, and the pressure film is provided above the reference pressure cavity; the third sensitive resistor is provided on the first side of the pressure film, the fourth sensitive resistor is provided on the second side of the pressure film, and the first side is arranged opposite to the second side; the fifth sensitive resistor is provided on the third side of the pressure film, and the sixth sensitive resistor is provided on the fourth side of the pressure film, and the third side is arranged opposite to the fourth side; the first end of the third sensitive resistor is connected to the first end of the fifth sensitive resistor, and the second end is connected to the first end of the sixth sensitive resistor; the first end of the fourth sensitive resistor is connected to the second end of the fifth sensitive resistor, and the second end is connected to the second end of the sixth sensitive resistor; wherein an insulating layer is provided between the third sensitive resistor, the fourth sensitive resistor, the fifth sensitive resistor and the sixth sensitive resistor and the single crystal silicon substrate.

7. The method for preparing a single-chip composite sensor structure according to claim 6, characterized in that: The release hole group is along the crystal direction <211> arrangement.

8. The method for preparing a single-chip composite sensor structure according to claim 1, characterized in that: In step S3, first, the insulating layer in the area where the sensitive resistor is located is removed, and the sensitive resistor is prepared by boron ion implantation; Then, a first passivation layer is deposited on the single crystal silicon substrate, and the first passivation layer, the insulating layer and the single crystal silicon substrate are etched to obtain a group of release holes of the pressure sensor.

9. The method for preparing a single-chip composite sensor structure according to claim 1, characterized in that: In step S4, a second passivation layer is deposited on the sidewalls of the release hole group, and then a sacrificial gap is etched in the single crystal silicon substrate; the single crystal silicon substrate below the release hole group is selectively corroded to form the pressure film and the reference pressure cavity; filling the release hole group with second polysilicon to stitch the release hole group; A third passivation layer and a second silicon nitride layer are sequentially deposited on the single crystal silicon substrate, and the second silicon nitride layer and the third passivation layer above the sensitive resistor are removed to prepare a lead hole.

10. The method for preparing a single-chip composite sensor structure according to claim 9, characterized in that: Step S4 also includes: after stitching the release hole groups, thinning the third passivation layer to eliminate the process etching margin in step S3.

11. The method for preparing a single-chip composite sensor structure according to claim 1, characterized in that: In step S5, a fourth passivation layer and a third silicon nitride layer are sequentially deposited on the single crystal silicon substrate, and a portion of the insulating layer, the silicon nitride layer and the passivation layer in the angular velocity sensor region are etched away to form a fixed electrode in the angular velocity sensor.

12. The method for preparing a single-chip composite sensor structure according to claim 1, characterized in that: In step S6, a fifth passivation layer is deposited on the single crystal silicon substrate, and the single crystal silicon substrate is etched to form a release groove of the cantilever beam of the acceleration sensor; depositing a sixth passivation layer on the sidewall of the release groove, and then etching a groove of a first preset depth in the single crystal silicon substrate; The cantilever beam of the acceleration sensor is selectively etched; wherein the first preset depth is greater than the thickness of the mass block.

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