A dual-range acceleration sensor structure and manufacturing method

Abstract

The present invention provides a dual-range acceleration sensor structure and manufacturing method, the method comprising: providing a substrate; forming a first groove on the back side of the substrate and forming a plurality of piezoresistors on the front side of the substrate; forming a dielectric layer on the front side of the substrate, wherein an opening is provided in the dielectric layer to expose the piezoresistors; selectively etching a high-range acceleration sensor based on a cantilever beam structure inside the substrate; forming a metal layer on the front side of the substrate, wherein the metal layer also extends into the opening to be electrically connected to the piezoresistors; forming a fifth groove of a preset depth in the first groove and forming a sixth groove on the front side of the substrate, wherein the sixth groove corresponds to the fifth groove in a vertical direction and the sixth groove is connected to the fifth groove. In the dual-range acceleration sensor structure and manufacturing method of the present invention, by integrating a low-range acceleration sensor and a high-range acceleration sensor on a single chip, the dual-range acceleration sensor has the advantages of high sensitivity, high frequency response, high overload resistance, low cost, and miniaturization.

Description

Technical Field

[0001] The invention belongs to the technical field of sensors and relates to a dual-range acceleration sensor structure and a manufacturing method. Background Art

[0002] With the advancement of micromechanical system (MEMS) sensor technology, various MEMS sensors have attracted significant attention. Silicon-based accelerometers, among the most popular inertial sensors, have significant applications in aerospace, military fuses, shock measurement, wearable devices, automotive electronics, and other fields. To accurately reproduce the details of acceleration signals during collisions, takeoffs, and penetration, while minimizing signal distortion, accelerometers must possess not only high overload resistance and sufficient sensitivity, but also a high resonant frequency and operating bandwidth.

[0003] The working principle of the piezoresistive accelerometer is to use the piezoresistive effect of semiconductors. The mechanical strain generated by the acceleration force causes the resistivity of the piezoelectric material to change. This change is converted into a measurable signal output through an appropriate circuit to determine the acceleration. At present, the core detection components of the piezoresistive accelerometer are mainly composed of a suspended mechanical sensitive structure and a detection resistor, and are manufactured using the MEMS double-sided silicon micromachining process. In 2002, Dong Jian and others from the Shanghai Institute of Microsystem and Information Technology of the Chinese Academy of Sciences used the double-sided silicon micromachining process to manufacture a high-shock accelerometer with a lateral deflection cantilever structure and a piezoresistive sensing scheme, which can be used for the measurement range of tens of thousands of gravity [J.Dong, X.Li, Y.Wang, atal.Silicon micromachined high-shock accelerometers with a curved-surface-application structure for over-rang stop protection and free-mode-resonance depression, J. Micromech. Microeng. 2002, 12(6): 742-746], but there are the following shortcomings: a. The back-side etching of the (100) silicon wafer to form an inclined sidewall requires a large area, which makes the chip size large after processing and difficult to integrate; b. During the production process of the sensitive structure cantilever beam of the acceleration sensor, it takes a lot of time to use KOH solution to thin the silicon wafer over a large area and a large depth to the expected structural beam thickness, which prolongs the production cycle and increases the production cost; c. The gap between the sensor cantilever beam processed by double-sided micromachining and the substrate is large, and there is not enough air pressure film damping perpendicular to the sensitive direction to suppress the parasitic signal interference caused by structural resonance, which limits the sensitivity of the sensor.In 2012, Wang Jiachou and others from the Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, used advanced single-wafer monohedral silicon micromachining technology to fabricate a multifunctional composite sensor chip with integrated pressure and acceleration detection functions on a single chip [JC Wang, XY Xia, and XX Li. Monolithic Integration of Pressure Plus Acceleration Composite TPMS Sensors With a Single-Sided Micromachining Technology, Journal of Microelectromechanical Systems, vol. 21, no. 2, pp. 284-293, Apr 2012]. They used copper electroplating on a mass block to enhance the sensitivity of the accelerometer. With the help of single-wafer monohedral silicon micromachining technology, they were able to integrate the two sensing elements into a very small chip, reducing costs. However, due to the structural design of the accelerometer, the sensor had a low frequency response and limited ability to withstand high overloads. In order to further improve the sensitivity and frequency response of the device, Taeyup Kim et al. from Seoul National University in South Korea proposed a method for preparing a piezoresistive accelerometer using silicon nanowires [Kim T, Jang S, Chang B, at al. A New Simple Fabrication Method for Silicon Nanowire-Based Accelerometers. 20th International Conference on Solid-State Sensors, Actuators and Microsystems & Eurosensors XXXIII (TRANSDUCERS & EUROSENSORS XXXIII), 2019, pp: 1949-1952]. The resistivity of this sensor changes dramatically with acceleration, and the chip size is also very small. However, the silicon nanowire process is difficult to manufacture, which affects the yield of the sensor chip. At the same time, the overload resistance of the manufactured accelerometer needs to be improved.

[0004] With the continuous development of MEMS technology, the structure of accelerometers is becoming increasingly diverse, and they are moving towards miniaturization, integration, high performance, and low cost. However, there are still some shortcomings, such as frequency response, overload resistance, and process cost, which still need significant improvement. Therefore, it is necessary to develop a dual-range accelerometer structure and preparation method. Summary of the Invention

[0005] In view of the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a dual-range acceleration sensor structure and preparation method to solve the problems of low frequency response, poor overload resistance and high process cost of the acceleration sensor in the prior art.

[0006] To achieve the above and other related objectives, the present invention provides a method for manufacturing a dual-range acceleration sensor structure, comprising the following steps:

[0007] Providing a substrate, the substrate comprising a front surface and a back surface disposed opposite to each other, wherein the substrate is divided into a low-range area and a high-range area;

[0008] forming a first trench on the back surface of the substrate, the first trench being located in the low-range region, and forming a plurality of piezoresistors on the front surface of the substrate, wherein at least a portion of the piezoresistors are located in the low-range region and at least a portion of the piezoresistors are located in the high-range region;

[0009] forming a dielectric layer on the front surface of the substrate, and forming an opening at a predetermined position of the dielectric layer, wherein the opening exposes the varistor;

[0010] forming a second trench on the front surface of the substrate and forming a resist layer on the sidewall of the second trench, wherein the second trench is located in the high range region;

[0011] forming a third trench of a predetermined depth in the substrate based on the second trench, and forming a fourth trench extending laterally in the substrate based on the third trench;

[0012] forming a metal layer on the dielectric layer, wherein the metal layer further extends into the opening and is electrically connected to the varistor;

[0013] forming a fifth trench with a predetermined depth in the first trench;

[0014] A sixth trench is formed on the front surface of the substrate, the sixth trench corresponds to the fifth trench in a vertical direction, and the sixth trench is connected to the fifth trench.

[0015] Optionally, the substrate comprises a (111) single crystal silicon wafer, and the second groove is along <110> and <211> The fifth groove is arranged along the crystal direction. <110> and <211> Crystal arrangement.

[0016] Optionally, before forming the sixth groove, the method further includes providing a supporting base and bonding the back side of the substrate to the supporting base.

[0017] Optionally, the step of forming the resist layer on the sidewall of the second trench includes:

[0018] forming the resist layer on the sidewall and bottom of the second trench by using a vapor deposition method;

[0019] The resist layer at the bottom of the second trench is removed by etching, and the resist layer at the sidewall of the second trench is retained.

[0020] Optionally, the first groove is used for the movable gap of the low-range acceleration sensor, and the depth of the first groove does not exceed 5 microns; the fourth groove is used for the movable gap of the high-range acceleration sensor, and the depth of the fourth groove is not less than 5 microns.

[0021] Optionally, the resist layer includes a stacked silicon nitride layer and a tetraethyl orthosilicate passivation layer.

[0022] Optionally, before forming the second trench, the method further includes forming a mask layer on the front surface of the substrate, wherein the mask layer includes a stacked ethyl orthosilicate passivation layer, a silicon nitride layer and a ethyl orthosilicate passivation layer.

[0023] The present invention also provides a dual-range acceleration sensor structure, comprising:

[0024] A substrate, the substrate comprising a front surface and a back surface arranged opposite to each other, wherein the substrate is divided into a low-range area and a high-range area;

[0025] a first trench located on the back side of the substrate, and the first trench is located in the low-range area;

[0026] a plurality of piezoresistors located on the front surface of the substrate, wherein at least a portion of the piezoresistors are located in the low-range region, and at least a portion of the piezoresistors are located in the high-range region;

[0027] a dielectric layer, located on the front surface of the substrate, wherein an opening is provided at a preset position of the dielectric layer, and the varistor is exposed by the opening;

[0028] a second groove located on the front surface of the substrate, and the second groove is located in the high-range area;

[0029] a third groove, located below the second groove and communicating with the second groove;

[0030] a fourth groove, located on a side of the third groove and connected to the third groove;

[0031] a metal layer, located above the dielectric layer, the metal layer also filling the opening and electrically connected to the varistor;

[0032] a fifth groove located in the first groove;

[0033] A sixth trench is located on the front surface of the substrate, the sixth trench corresponds to the fifth trench in a vertical direction, and the sixth trench is connected to the fifth trench.

[0034] Optionally, the substrate comprises a (111) single crystal silicon wafer, and the second groove is along <110> and <211> The fifth groove is arranged along the crystal direction. <110> and <211> Crystal arrangement.

[0035] Optionally, a supporting base is further included, wherein the supporting base is located on the back side of the substrate and bonded to the substrate.

[0036] As described above, the dual-range acceleration sensor structure and manufacturing method of the present invention integrates a low-range acceleration sensor and a high-range acceleration sensor on a single chip, thereby having the advantages of high sensitivity, high frequency response, high overload resistance, low cost, and miniaturization. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Shown is a flow chart of a method for manufacturing a dual-range acceleration sensor structure of the present invention.

[0038] Figure 2 Shown is a schematic diagram of providing a substrate in the present invention.

[0039] Figure 3 It is a schematic diagram showing the formation of a first trench on the back surface of a substrate and the formation of a varistor on the front surface of the substrate in the present invention.

[0040] Figure 4 It is a schematic diagram showing forming a dielectric layer on the front surface of a substrate and forming an opening in the dielectric layer in the present invention.

[0041] Figure 5 It is a schematic diagram showing the formation of a mask layer on the front side of a substrate in the present invention.

[0042] Figure 6 FIG. 1 is a schematic diagram showing the formation of a second trench on the front surface of the substrate according to the present invention.

[0043] Figure 7 It is a schematic diagram showing the formation of an etch-resist layer on the sidewall of the second trench according to the present invention.

[0044] Figure 8 It is a schematic diagram showing the formation of a third trench below the second trench in the present invention.

[0045] Figure 9 It is a schematic diagram showing the formation of a fourth trench on the side of the third trench in the present invention.

[0046] Figure 10 It is a schematic diagram showing the formation of a metal layer above a dielectric layer in the present invention.

[0047] Figure 11 FIG. 1 is a schematic diagram showing the formation of a fifth trench in the first trench according to the present invention.

[0048] Figure 12 It is a schematic diagram showing the bonding of a supporting base to the back surface of a substrate in the present invention.

[0049] Figure 13 FIG. 1 is a schematic diagram showing the formation of a sixth trench on the front surface of the substrate according to the present invention.

[0050] Figure 14 Shown is a perspective view of the dual-range acceleration sensor structure of the present invention.

[0051] Figure 15 Shown is a top view of the low-range acceleration sensor of the present invention.

[0052] Figure 16 Shown is a top view of the high-range acceleration sensor of the present invention.

[0053] Component number description

[0054] 1 substrate

[0055] 101 Low range area

[0056] 102 High range area

[0057] 103 Lower thermal oxide layer

[0058] 104 Upper thermal oxide layer

[0059] 2 First groove

[0060] 3 Varistors

[0061] 4 Dielectric layer

[0062] 4a Lower dielectric layer

[0063] 5 Opening

[0064] 6 Mask layer

[0065] 6a Lower mask layer

[0066] 7 Second groove

[0067] 8. Resist layer

[0068] 8a Lower resist layer

[0069] 9 Third groove

[0070] 10 Fourth groove

[0071] 11 Metal Layer

[0072] 12 Fifth groove

[0073] 13 Support base

[0074] 14 Sixth Groove

[0075] 15 Low-range accelerometer

[0076] 1501 Low Range Accelerometer Mass

[0077] 1502 Low Range Accelerometer Detection Beam

[0078] 1503 Low Range Accelerometer Cantilever

[0079] 1504 Low Range Accelerometer Movable Gap

[0080] 16 High-range accelerometers

[0081] 1601 High Range Accelerometer Cantilever

[0082] 1602 High Range Accelerometer Movable Gap

[0083] Steps S1 to S8 DETAILED DESCRIPTION

[0084] 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.

[0085] See also Figures 1 to 16 It should be noted that the diagrams provided in this embodiment are merely schematic illustrations of 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 may be changed arbitrarily, and the component layout may also be more complex.

[0086] This embodiment provides a method for manufacturing a dual-range acceleration sensor structure. Figure 1 , shown as a process flow diagram of the method, comprising the following steps:

[0087] S1: providing a substrate, wherein the substrate comprises a front surface and a back surface opposite to each other, wherein the substrate is divided into a low-range region and a high-range region;

[0088] S2: forming a first trench on the back surface of the substrate, the first trench being located in the low-range region, and forming a plurality of piezoresistors on the front surface of the substrate, wherein at least a portion of the piezoresistors are located in the low-range region, and at least a portion of the piezoresistors are located in the high-range region;

[0089] S3: forming a dielectric layer on the front surface of the substrate, and forming an opening at a predetermined position of the dielectric layer, wherein the opening exposes the varistor;

[0090] S4: forming a second trench on the front surface of the substrate, and forming a resist layer on the sidewall of the second trench, wherein the second trench is located in the high range region;

[0091] S5: forming a third trench of a predetermined depth in the substrate based on the second trench, and forming a fourth trench extending laterally in the substrate based on the third trench;

[0092] S6: forming a metal layer on the dielectric layer, wherein the metal layer is further filled into the opening and electrically connected to the varistor;

[0093] S7: forming a fifth trench with a predetermined depth in the first trench;

[0094] S8: forming a sixth trench on the front surface of the substrate, wherein the sixth trench corresponds to the fifth trench in a vertical direction and the sixth trench is connected to the fifth trench.

[0095] First, see Figure 2 , performing step S1: providing a substrate 1, wherein the substrate 1 includes a front surface and a back surface arranged opposite to each other, wherein the substrate 1 is divided into a low-range area 101 and a high-range area 102.

[0096] As an example, the substrate 1 includes a silicon substrate, a germanium substrate, a silicon germanium substrate or any other suitable semiconductor substrate. Specifically, in this embodiment, the substrate 1 is a (111) single crystal silicon wafer.

[0097] As an example, the low-range area 101 is used for subsequent processing of a low-range acceleration sensor, and the high-range area 102 is used for subsequent processing of a high-range acceleration sensor.

[0098] Next, see Figure 3 , execute step S2: form a first groove 2 on the back side of the substrate 1, the first groove 2 is located in the low-range area 102, and form a plurality of varistors 3 on the front side of the substrate 1, wherein at least a portion of the varistors 3 are located in the low-range area 101, and at least a portion of the varistors 3 are located in the high-range area 102.

[0099] As an example, before forming the first groove 2, the steps of forming a lower thermal oxide layer 103 on the back side of the substrate 1 and forming an upper thermal oxide layer 104 on the front side of the substrate 1 are also included; and, the lower oxide layer 103 is patterned, and the substrate 1 is etched based on the patterned lower oxide layer 103 to form the first groove 2; the upper oxide layer 104 is patterned, and ion implantation diffusion is performed based on the patterned upper oxide layer 104 to form the varistor 3.

[0100] As an example, the substrate 1 is etched by silicon deep reactive ion etching (DRIE) to form the first trench 2 , the depth of which does not exceed 5 μm, serving as a movable gap in the Z-axis direction of the low-range acceleration sensor.

[0101] As an example, during the formation of the varistor 3 , the implanted ions include boron ions, which are then subjected to high-temperature treatment. High-temperature treatment is beneficial to the diffusion of boron ions and can repair damage to the crystal lattice caused by the ion implantation.

[0102] As an example, after forming the first trench 2 and the varistor 3 , the method further includes removing the lower oxide layer 103 and the upper oxide layer 104 .

[0103] Next, see Figure 4 , executing step S3: forming a dielectric layer 4 on the front surface of the substrate 1 , and forming an opening 5 at a preset position of the dielectric layer 4 , wherein the opening 5 exposes the varistor 3 .

[0104] As an example, the dielectric layer 4 includes a low-stress silicon nitride layer, which is formed by low-pressure chemical vapor deposition (LPCVD) or other suitable methods; and also includes a step of forming a lower dielectric layer 4a on the back side of the substrate 1 to balance the front and back stresses of the substrate 1.

[0105] As an example, the opening 5 is formed in the dielectric layer 4 by etching, and the opening 5 is used for subsequently leading out the electrode of the varistor 3 .

[0106] As an example, see Figure 5After forming the opening 5, the method further includes forming a mask layer 6 above the dielectric layer 4. The mask layer 6 serves as a mask for subsequent front processing. The mask layer 6 includes a stacked tetraethyl orthosilicate (TEOS) passivation layer, a low-stress silicon nitride layer, and a TEOS passivation layer, wherein the TEOS passivation layer is a compressive stress film layer and the silicon nitride layer is a tensile stress film layer. The stress of the mask layer 6 is reduced by stacking the TEOS passivation layer, the low-stress silicon nitride layer, and the TEOS passivation layer. The method further includes forming a lower mask layer 6a on the back side of the substrate 1 to balance the stress on the front and back sides of the substrate 1.

[0107] Next, see Figures 6 and 7 , executing step S4: forming a second trench 7 on the front surface of the substrate 1 and forming a resist layer 8 on the sidewall of the second trench 7, wherein the second trench 7 is located in the high range region 102.

[0108] As an example, Figure 6 As shown, the mask layer 6 is patterned, and based on the patterned mask layer 6, the substrate 1 is etched by DRIE to form the second trench 7. The etching of the substrate 1 also includes etching the dielectric layer 4.

[0109] As an example, the second groove 7 is along <110> and <211> The second groove 7 is used for the movable gap of the high-range acceleration sensor (see the subsequent Figure 16 ), wherein the depth of the second groove 7 is the thickness of the cantilever beam of the high-range acceleration sensor.

[0110] As an example, Figure 7 As shown, the etch-stop layer 8 is formed on the sidewall of the second trench 7. The etch-stop layer 8 is used to protect the sidewall of the second trench 7. The etch-stop layer 8 includes a low-stress silicon nitride and a TEOS passivation layer. Specifically, the step of forming the etch-stop layer 8 on the sidewall of the second trench 7 includes:

[0111] (1) using LPCVD to sequentially deposit a low-stress silicon nitride layer and a TEOS passivation layer on the sidewalls and bottom of the second trench 7;

[0112] (2) removing the low-stress silicon nitride layer and the TEOS passivation layer at the bottom of the second trench 7 , and retaining the low-stress silicon nitride layer and the TEOS passivation layer on the sidewalls of the second trench 7 .

[0113] Next, see Figures 8 and 9 , executing step S5: forming a third trench 9 of a preset depth in the substrate 1 based on the second trench 7 , and forming a laterally extended fourth trench 10 in the substrate 1 based on the third trench 9 .

[0114] As an example, Figure 8 As shown, the substrate 1 is further etched along the bottom of the second groove 7 by the DRIE method to form the third groove 9 of a preset depth. The depth of the third groove 9 is the movable gap depth of the high-range acceleration sensor in the Z-axis direction.

[0115] As an example, Figure 9 As shown, based on the third groove 9, the substrate 1 is laterally wet-etched by a KOH or TMAH etching solution to form the fourth groove 10, and the fourth groove 10 is used for the movable gap of the high-range acceleration sensor in the Z-axis direction; wherein, the second groove 7 and the fourth groove 10 define the cantilever beam structure of the high-range acceleration sensor.

[0116] Next, see Figure 10 , executing step S6: forming a metal layer 11 on the dielectric layer 4 , and the metal layer 11 is also filled into the opening 5 to be electrically connected to the varistor 3 .

[0117] As an example, before forming the metal layer 11, a step of removing the mask layer 6 is also included. After removing the mask layer 6, a sputtering method is used to form metal on top of the dielectric layer 4 and pattern it to form the metal layer 11. The metal layer 11 is used for metal lead interconnection and pads.

[0118] Next, see Figure 11 , executing step S7: forming a fifth trench 12 with a preset depth in the first trench 2.

[0119] As an example, the lower mask layer 6 a located on the back side of the substrate 1 is patterned, and based on the patterned lower mask layer 6 a , the substrate 1 is etched using a DRIE method to form the fifth trench 12 .

[0120] As an example, the fifth groove 12 is along <110> and <211> The fifth groove 12 defines the mass block, cantilever beam and detection beam structure of the low-range acceleration sensor (see subsequent Figure 15 ), and the fifth groove 12 is used for the movable gap of the low-range acceleration sensor.

[0121] As an example, after the fifth trench 12 is formed, the lower mask layer 6 a and the lower dielectric layer 4 a located on the back side of the substrate 1 are removed by etching.

[0122] Next, see Figures 12 to 13, executing step S8: forming a sixth trench 14 on the front surface of the substrate 1, wherein the sixth trench 14 corresponds to the fifth trench 12 in a vertical direction, and the sixth trench 14 is connected to the fifth trench 12.

[0123] As an example, see Figure 12 Before forming the sixth groove 14, the method further includes providing a supporting base 13 and bonding the back side of the substrate 1 to the supporting base 13. The supporting base 13 is used as a supporting structure of the sensor frame. Specifically, in this embodiment, the supporting base 13 is made of glass, and the back side of the substrate 1 is bonded to the glass by anodic electrostatic bonding.

[0124] As an example, see Figure 13 , the substrate 1 is etched using a DRIE method to form the sixth trench 14 .

[0125] So far, a dual-range acceleration sensor structure has been obtained. Figure 13 and Figure 14 , respectively showing a cross-sectional view and a stereoscopic view of the dual-range acceleration sensor structure, the dual-range acceleration sensor structure comprising a substrate 1, a first groove 2, a plurality of piezoresistors 3, a dielectric layer 4, a second groove 7, a third groove 9, a fourth groove 10, a metal layer 11, a fifth groove 12 and a sixth groove 14, wherein the substrate 1 comprises a front side and a back side arranged opposite to each other, the substrate 1 being divided into a low-range region 101 and a high-range region 102; the first groove 2 is located on the back side of the substrate 1, and the first groove 2 is located in the low-range region 101; the piezoresistors 3 are located on the front side of the substrate 1, at least a portion of the piezoresistors 3 are located in the low-range region 101, and at least a portion of the piezoresistors 3 are located in the high-range region 102; the dielectric layer 4 is located on the substrate 1 On the front side, an opening 5 is provided at a preset position of the dielectric layer 4, and the opening 5 reveals the varistor 3; the second groove 7 is located on the front side of the substrate 1, and the second groove 7 is located in the high-range area 102; the third groove 9 is located below the second groove 7 and is connected to the second groove 7; the fourth groove 10 is located on the side of the third groove 9 and is connected to the third groove 9; the metal layer 11 is located above the dielectric layer 4, and the metal layer 11 is also filled into the opening 5 and is electrically connected to the varistor 3; the fifth groove 12 is located in the first groove 2; the sixth groove 14 is located on the front side of the substrate 1, and the sixth groove 14 corresponds to the fifth groove 15 in the vertical direction, and the sixth groove 14 is connected to the fifth groove 12.

[0126] As an example, the first groove 2 is used for the movable gap of the low-range acceleration sensor 15 in the Z direction, and the fifth groove 12 and the sixth groove 14 are used for the movable gap of the low-range acceleration sensor 15 in the X direction and the Y direction; see Figure 15 , showing a top view of the low-range acceleration sensor 15, including a low-range acceleration sensor mass block 1501, a low-range acceleration sensor detection beam 1502 and a low-range acceleration sensor cantilever beam 1503, wherein the low-range acceleration sensor mass block 1501 includes a mass block body and a mass foot protruding from the mass block body, the low-range acceleration sensor detection beam 1502 is a direct pull and direct compression detection beam, the low-range acceleration sensor detection beam 1502 is located at the top of the mass foot and connected to the mass foot, the low-range acceleration sensor cantilever beam 1503 03 is connected to the low-range acceleration sensor mass block 1501 to provide support for the low-range acceleration sensor mass block 1501. A low-range acceleration sensor movable gap 1504 is set around the low-range acceleration sensor mass block 1501. Its working principle is: the low-range acceleration sensor mass block 1501 swings in the low-range acceleration sensor movable gap 1504 under the action of acceleration force, causing the low-range acceleration sensor detection beam 1502 to undergo mechanical strain, thereby causing the resistivity of the piezoresistor 3 to change, and the acceleration is determined by the change in resistivity.

[0127] As an example, in this embodiment, one of the low-range acceleration sensor mass blocks 1501 is provided with two of the mass feet, and the two mass feet correspond to two of the low-range acceleration sensor detection beams 1502. In other examples, one of the low-range acceleration sensor mass blocks 1501 can be provided with less than two or more than two of the low-range acceleration sensor detection beams 1502, which is not limited to this embodiment.

[0128] As an example, the fourth groove 10 is used for the movable gap of the high-range acceleration sensor 16 in the Z direction, and the second groove 7 is used for the movable gap of the high-range acceleration sensor 16 in the X and Y directions. Figure 16 , showing a top view of the high-range acceleration sensor 16, including a high-range acceleration sensor cantilever beam 1601, and a high-range acceleration sensor movable gap 1602 is arranged around the high-range acceleration sensor cantilever beam 1601. Its working principle is: the high-range acceleration sensor cantilever beam 1601 swings in the high-range acceleration sensor movable gap 1602 under the action of the acceleration force, so that the area where the high-range acceleration sensor cantilever beam 1601 contacts the piezoresistor 3 is strained, thereby causing the resistivity of the piezoresistor 3 to change, and the acceleration is determined by the change in resistivity.

[0129] As an example, the acceleration range measured by the low-range acceleration sensor 15 is in the order of 10E1 to 10E3 (m / s 2 ), the acceleration range measured by the high-range acceleration sensor 16 is in the order of 10E3 to 10E5 (m / s 2 ), by integrating the dual-range accelerometer on a single chip, it has the advantages of high sensitivity, high frequency response, high overload resistance, low cost and miniaturization.

[0130] In summary, the dual-range accelerometer structure and fabrication method of the present invention, by integrating a low-range accelerometer and a high-range accelerometer on a single chip, offers the advantages of high sensitivity, high frequency response, high overload resistance, low cost, and miniaturization. Therefore, this invention effectively overcomes the shortcomings of existing technologies and possesses high industrial value.

[0131] 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 manufacturing a dual-range acceleration sensor structure, characterized in that: The following steps are involved: Providing a substrate, the substrate comprising a front surface and a back surface disposed opposite to each other, wherein the substrate is divided into a low-range area and a high-range area; forming a first trench on the back surface of the substrate, the first trench being located in the low-range region, and forming a plurality of piezoresistors on the front surface of the substrate, wherein at least a portion of the piezoresistors are located in the low-range region and at least a portion of the piezoresistors are located in the high-range region; forming a dielectric layer on the front surface of the substrate, and forming an opening at a predetermined position of the dielectric layer, wherein the opening exposes the varistor; forming a second trench on the front surface of the substrate and forming a resist layer on the sidewall of the second trench, wherein the second trench is located in the high range region; forming a third trench of a predetermined depth in the substrate based on the second trench, and forming a fourth trench extending laterally in the substrate based on the third trench; forming a metal layer on the dielectric layer, wherein the metal layer is further filled into the opening and electrically connected to the varistor; forming a fifth trench with a predetermined depth in the first trench; A sixth trench is formed on the front surface of the substrate, the sixth trench corresponds to the fifth trench in a vertical direction, and the sixth trench is connected to the fifth trench.

2. The method for manufacturing a dual-range acceleration sensor structure according to claim 1, wherein: The substrate comprises a (111) single crystal silicon wafer, and the second groove is along <110> and <211> The fifth groove is arranged along the crystal direction. <110> and <211> Crystal arrangement.

3. The method for manufacturing a dual-range acceleration sensor structure according to claim 1, wherein: Before forming the sixth groove, the method further includes providing a supporting base and bonding the back surface of the substrate to the supporting base.

4. The method for manufacturing a dual-range acceleration sensor structure according to claim 1, wherein: The step of forming the resist layer on the sidewall of the second trench includes: forming the resist layer on the sidewall and bottom of the second trench by using a vapor deposition method; The resist layer at the bottom of the second trench is removed by etching, and the resist layer at the sidewall of the second trench is retained.

5. The method for manufacturing a dual-range acceleration sensor structure according to claim 1, wherein: The first groove is used for the movable gap of the low-range acceleration sensor, and the depth of the first groove does not exceed 5 microns; the fourth groove is used for the movable gap of the high-range acceleration sensor, and the depth of the fourth groove is not less than 5 microns.

6. The method for manufacturing a dual-range acceleration sensor structure according to claim 1, wherein: The resist layer includes a stacked silicon nitride layer and a tetraethyl orthosilicate passivation layer.

7. The method for manufacturing a dual-range acceleration sensor structure according to claim 1, wherein: Before forming the second trench, the method further includes forming a mask layer on the front surface of the substrate, wherein the mask layer includes a stacked ethyl orthosilicate passivation layer, a silicon nitride layer and a ethyl orthosilicate passivation layer.

8. A dual-range acceleration sensor structure, characterized in that: include: A substrate, the substrate comprising a front surface and a back surface arranged opposite to each other, wherein the substrate is divided into a low-range area and a high-range area; a first trench located on the back side of the substrate, and the first trench is located in the low-range area; a plurality of piezoresistors located on the front surface of the substrate, wherein at least a portion of the piezoresistors are located in the low-range region, and at least a portion of the piezoresistors are located in the high-range region; a dielectric layer, located on the front surface of the substrate, wherein an opening is provided at a preset position of the dielectric layer, and the varistor is exposed by the opening; a second groove located on the front surface of the substrate, and the second groove is located in the high-range area; a third groove, located below the second groove and communicating with the second groove; a fourth groove, located on a side of the third groove and connected to the third groove; a metal layer, located above the dielectric layer, the metal layer also filling the opening and electrically connected to the varistor; a fifth groove located in the first groove; A sixth trench is located on the front surface of the substrate, the sixth trench corresponds to the fifth trench in a vertical direction, and the sixth trench is connected to the fifth trench.

9. The dual-range acceleration sensor structure according to claim 8, characterized in that: The substrate comprises a (111) single crystal silicon wafer, and the second groove is along <110> and <211> The fifth groove is arranged along the crystal direction. <110> and <211> Crystal arrangement.

10. The dual-range acceleration sensor structure according to claim 8, characterized in that: The invention also includes a supporting base, which is located on the back side of the substrate and bonded to the substrate.

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