MEMS sensor

Abstract

The utility model provides an MEMS sensor which comprises a first substrate and a torsion swing rod, two opposite sides of the torsion swing rod are respectively provided with a detection capacitor and a torsion swing block which are sequentially arranged from inside to outside, and a first electrode structure and a second electrode structure of each detection capacitor are sequentially arranged on the first substrate from bottom to top. A first torsional pendulum structure and a second torsional pendulum structure of the torsional pendulum block are sequentially arranged on a first substrate from bottom to top, only a torsional pendulum rod and a second electrode structure are fixed to the first substrate, when the acceleration is sensed, the first torsional pendulum structure, the second torsional pendulum structure, the first electrode structure and the torsional pendulum rod can synchronously move, the capacitance value of a detection capacitor is changed, and the detection precision is improved. Acceleration measurement is realized. The first electrode structure and the second electrode structure are not directly contacted with the first substrate, so that even if the first substrate is bent and deformed, the capacitance value of the detection capacitor is not excessively influenced, and the accuracy and the stability of detection are improved; the torsional pendulum block is formed by connecting two layers of torsional pendulum structures, the sensitivity is improved, and meanwhile the influence of noise is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of semiconductor manufacturing, in particular to a MEMS sensor. Background Art

[0002] An accelerometer is a micro-electro-mechanical system (MEMS) inertial sensor, which is mainly used in the fields of position sensing, displacement sensing or motion state sensing. The more common accelerometers on the market currently directly make an electrode layer of the detection capacitor on the substrate and directly contact the substrate. Although this type of accelerometer has high accuracy and sensitivity, due to changes in external environmental conditions or the introduction of mechanical stress, the internal substrate may bend and deform after packaging, causing the capacitance of the detection capacitor corresponding to the electrode layer in contact with the substrate to change in the absence of external acceleration, resulting in a deviation in the output signal, which in turn leads to inaccurate detection results. Utility Model Content

[0003] The utility model aims to provide a MEMS sensor to solve the problem of inaccurate detection results of existing MEMS sensors.

[0004] In order to achieve the above object, the utility model provides a MEMS sensor, including a first substrate and a torsion yaw bar, wherein two opposite sides of the torsion yaw bar have detection capacitors and torsion yaw blocks arranged in sequence from the inside to the outside;

[0005] The detection capacitor includes a first electrode structure and a second electrode structure sequentially arranged on the first substrate from bottom to top, the torsion pendulum block includes a first torsion pendulum structure and a second torsion pendulum structure sequentially arranged on the first substrate from bottom to top, and the torsion pendulum rod and the second electrode structure are fixed on the first substrate; and,

[0006] The first torsion pendulum structure, the second torsion pendulum structure, the first electrode structure and the torsion pendulum rod are connected to each other to move synchronously, and are isolated from the second electrode structure.

[0007] Optionally, the MEMS sensor is an accelerometer.

[0008] Optionally, under the action of acceleration, the MEMS sensor twists the torsion pendulum laterally and each of the torsion pendulum blocks swings longitudinally, so that each of the first electrode structures tilts longitudinally, changing the distance between each of the first electrode structures and the corresponding second electrode structure, so as to change the capacitance of each of the detection capacitors.

[0009] Optionally, the two torsion pendulum blocks swing in opposite directions, so that the capacitances of the two detection capacitors change in opposite directions, and a differential signal is obtained.

[0010] Optionally, the torsion pendulum rod includes a third torsion pendulum structure and a fourth torsion pendulum structure which are arranged on the first substrate from bottom to top, the third torsion pendulum structure and the fourth torsion pendulum structure are connected to each other, the first electrode structure, the first torsion pendulum structure and the third torsion pendulum structure are located on the same layer, and the second electrode structure, the second torsion pendulum structure and the fourth torsion pendulum structure are located on the same layer.

[0011] Optionally, a first anchor point is provided at the bottom of the third torsion pendulum structure, and the third torsion pendulum structure and the second electrode structure are both fixed on the first substrate through the first anchor point.

[0012] Optionally, the first anchor point is located in a central area of ​​the third torsion pendulum structure.

[0013] Optionally, the third torsion pendulum structure and the fourth torsion pendulum structure are both in strip shape, the first torsion pendulum structure is integrated with the first electrode structure, both ends of the first electrode structure have a first extension part, and the first electrode structure is connected to both ends of the third torsion pendulum structure through the first extension part; and

[0014] Both ends of the second torsion pendulum structure have second extension parts, and the second torsion pendulum structure is connected to both ends of the fourth torsion pendulum structure through the second extension parts. The second electrode structure is located between the two second extension parts and directly above the first electrode structure.

[0015] Optionally, a stop block is further provided between the torsion pendulum block and the corresponding detection capacitor, and the stop block is fixed on the first substrate.

[0016] Optionally, the stop block includes a first stop structure and a second stop structure which are sequentially arranged on the first substrate from bottom to top, and the stop structure and the second stop structure are connected to each other; and,

[0017] The first stop structure is located between the first electrode structure and the first torsion pendulum structure, and is isolated from the first electrode structure and the first torsion pendulum structure. The second stop structure is located between the second electrode structure and the second torsion pendulum structure, and is isolated from the second electrode structure and the second torsion pendulum structure.

[0018] Optionally, a second anchor point is provided at the bottom of the first stopping structure, and the first stopping structure is fixed on the first substrate through the second anchor point.

[0019] Optionally, the first electrode structure, the second electrode structure, the first torsion pendulum structure and the second torsion pendulum structure all have a plurality of release holes.

[0020] Optionally, the masses of the two torsion pendulum blocks are different.

[0021] Optionally, the first torsion pendulum structure is aligned with the release hole on the corresponding second torsion pendulum structure in the longitudinal direction; and / or, the first electrode structure is aligned with the release hole on the corresponding second electrode structure in the longitudinal direction.

[0022] Optionally, also include:

[0023] A second substrate is disposed opposite to the first substrate; and

[0024] The supporting wall is located between the first substrate and the second substrate, and together with the first substrate and the second substrate, forms a closed cavity. The torsion pendulum rod, the detection capacitor and the torsion pendulum block are all located in the cavity.

[0025] Optionally, also include:

[0026] A bonding structure is located between the supporting wall and the second substrate.

[0027] Optionally, also include:

[0028] a buried layer, located on the first substrate, wherein the buried layer has an alignment mark; and

[0029] The protection layer is located on the buried layer.

[0030] The MEMS sensor provided by the utility model includes a first substrate and a torsion pendulum rod, and the opposite sides of the torsion pendulum rod have detection capacitors and torsion pendulum blocks arranged in sequence from the inside to the outside. The first electrode structure and the second electrode structure of the detection capacitor are arranged in sequence from bottom to top on the first substrate, and the first torsion pendulum structure and the second torsion pendulum structure of the torsion pendulum block are arranged in sequence from bottom to top on the first substrate. Only the torsion pendulum rod and the second electrode structure are fixed on the first substrate. The first torsion pendulum structure, the second torsion pendulum structure, the first electrode structure and the torsion pendulum rod are connected to each other. When acceleration is sensed, the first torsion pendulum structure, the second torsion pendulum structure, the first electrode structure and the torsion pendulum rod can move synchronously to change the capacitance of the detection capacitor to achieve acceleration measurement. Since the first electrode structure and the second electrode structure are both arranged above the first substrate and are not in direct contact with the first substrate, even if the first substrate is bent and deformed, the capacitance of the detection capacitor will not be affected too much, thereby improving the problem of output signal deviation caused by factors such as packaging stress and improving the accuracy and stability of detection; and the torsion pendulum block is connected by two layers of torsion pendulum structure, which increases the mass of the torsion pendulum block, improves the sensitivity and reduces the influence of noise. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 to Figure 14 A schematic diagram of the structure corresponding to the corresponding steps of the method for preparing a MEMS sensor provided in an embodiment of the utility model;

[0032] Fig.15 A schematic plan view of a MEMS sensor provided by an embodiment of the utility model, Fig.14 for Fig.15 Schematic diagram of the cross section of the MEMS sensor along the AA direction;

[0033] Fig.16 for Fig.14 Schematic diagram of the cross section of the MEMS sensor along the BB direction;

[0034] Fig.17 for Fig.14 Schematic diagram of the cross section of the MEMS sensor along the CC direction;

[0035] Fig.18 and Fig.19 A schematic diagram of the movement of a MEMS sensor under the action of acceleration provided by an embodiment of the utility model;

[0036] Wherein, the accompanying drawings are marked as follows:

[0037] 100-first substrate; 102-second substrate; 201-buried layer; 202-protective layer; 301-conductive structure; 302-second conductive layer; 302a, 303a-release holes; 401-first sacrificial layer; 401a-first through hole; 402-second sacrificial layer; 402a-second through hole; 312-first anchor point; 322-second anchor point; 332-third torsion pendulum structure; 342-first electrode structure; 352-first stop structure; 362-first A torsion pendulum structure; 372-a first supporting structure; 403-a third sacrificial layer; 403a-a third through hole; 303-a third conductive layer; 313-a fourth torsion pendulum structure; 323-a second electrode structure; 333-a second stop structure; 343-a second torsion pendulum structure; 353-a second supporting structure; 303b-a fourth through hole; 500-a bonding structure; 601-a torsion pendulum rod; 602-a detection capacitor; 603-a stop block; 604-a torsion pendulum block; 605-a supporting wall. DETAILED DESCRIPTION

[0038] The following will describe the specific implementation of the utility model in more detail with reference to the schematic diagram. The advantages and features of the utility model will become clearer according to the following description. It should be noted that the drawings are all in a very simplified form and are not in exact proportions, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the utility model.

[0039] Fig.15 A schematic plan view of a MEMS sensor provided in this embodiment, Fig.14 for Fig.15 Schematic diagram of the cross section of the MEMS sensor along the AA direction. Fig.14 and Fig.15 As shown, the MEMS sensor includes a first substrate 100, a second substrate 102 and a supporting wall 605. The first substrate 100 and the second substrate 102 are arranged opposite to each other in the vertical direction, and the supporting wall 605 is annular and is located between the first substrate 100 and the second substrate 102, and together with the first substrate 100 and the second substrate 102, forms a closed cavity.

[0040] The cavity has a detection structure, which includes a torsion yaw bar 601, two detection capacitors 602, two stop blocks 603 and two torsion yaw blocks 604. The torsion yaw bar 601 is located in the center of the cavity, and has a first side and a second side ( Fig.15The two detection capacitors 602 are respectively arranged on the first side and the second side of the torsion yaw bar 601, the two stop blocks 603 are also respectively arranged on the first side and the second side of the torsion yaw bar 601, and the two torsion yaw blocks 604 are also respectively arranged on the first side and the second side of the torsion yaw bar 601. Moreover, the detection capacitor 602 is closer to the torsion yaw bar 601 than the stop block 603, and the stop block 603 is closer to the torsion yaw bar 601 than the torsion yaw block 604. That is to say, the torsion yaw bar 601, the detection capacitor 602, the stop block 603 and the torsion yaw block 604 are arranged in sequence from the inside to the outside. In this embodiment, the two detection capacitors 602 are symmetrically arranged relative to the center of the torsion yaw bar 601, and the two stop blocks 603 are symmetrically arranged relative to the center of the torsion yaw bar 601, but it should not be limited thereto.

[0041] Fig.16 for Fig.14 Schematic diagram of the cross section of the MEMS sensor along the BB direction, Fig.17 for Fig.14 Schematic diagram of the cross section of the MEMS sensor along the CC direction. Fig.14 , Fig.16 and Fig.17 As shown, the torsion pendulum rod 601 includes a third torsion pendulum structure 332 and a fourth torsion pendulum structure 313 arranged in sequence from bottom to top, the detection capacitor 602 includes a first electrode structure 342 and a second electrode structure 323 arranged in sequence from bottom to top, the stop block 603 includes a first stop structure 352 and a second stop structure 333 arranged in sequence from bottom to top, and the torsion pendulum block 604 includes a first torsion pendulum structure 362 and a second torsion pendulum structure 343 arranged in sequence from bottom to top. The third wiggling structure 332, the fourth wiggling structure 313, the first electrode structure 342, the second electrode structure 323, the first wiggling structure 362, the second wiggling structure 343, the first stop structure 352 and the second stop structure 333 are all located above the first substrate 100, and the third wiggling structure 332, the first electrode structure 342, the first wiggling structure 362 and the first stop structure 352 are located on the same layer, and the fourth wiggling structure 313, the second electrode structure 323, the second wiggling structure 343 and the second stop structure 333 are located on the same layer.

[0042] Further, the first torsion pendulum structure 362, the first electrode structure 342 and the third torsion pendulum structure 332 are connected to each other in the transverse direction, and the first torsion pendulum structure 362, the first electrode structure 342 and the third torsion pendulum structure 332 are isolated from each other in the transverse direction from the first stop structure 352. The second torsion pendulum structure 343 and the fourth torsion pendulum structure 313 are connected to each other in the transverse direction, the second torsion pendulum structure 343 and the fourth torsion pendulum structure 313 are isolated from each other in the transverse direction from the second electrode structure 323, and the second torsion pendulum structure 343 and the fourth torsion pendulum structure 313 are isolated from each other in the transverse direction from the second stop structure 333. The first torsion pendulum structure 362 and the second torsion pendulum structure 343 are connected to each other in the longitudinal direction, the third torsion pendulum structure 332 and the fourth torsion pendulum structure 313 are connected to each other in the longitudinal direction, the first stop structure 352 and the second stop structure 333 are connected to each other in the longitudinal direction, and the first electrode structure 342 and the second electrode structure 323 are isolated from each other in the longitudinal direction. It can be seen that the first stopping structure 352 , the second stopping structure 333 , and the second electrode structure 323 are isolated in the transverse direction, and the first electrode structure 342 and the second electrode structure 323 are isolated in the longitudinal direction.

[0043] In this way, the first torsion pendulum structure 362, the second torsion pendulum structure 343, the first electrode structure 342 and the torsion pendulum rod 601 are connected to each other and can move synchronously, while the second electrode structure 323, the first stop structure 352 and the second stop structure 333 will not move accordingly.

[0044] Specifically, if Fig.16 and Fig.17As shown, the third torsion pendulum structure 332 and the fourth torsion pendulum structure 313 are both in strip shape, the first torsion pendulum structure 362 is connected to the first electrode structure 342 as a whole, and the first stop structure 352 is located therein for distinguishing the first torsion pendulum structure 362 from the first electrode structure 342, and both ends of the first electrode structure 342 have first extensions, and both ends of the first electrode structure 342 are connected to both ends of the third torsion pendulum structure 332 through one of the first extensions. Both ends of the second torsion pendulum structure 343 have second extensions, so that the second torsion pendulum structure 343 is in a C shape, and both ends of the second torsion pendulum structure 343 are connected to both ends of the fourth torsion pendulum structure 313 through one of the second extensions. The second electrode structure 323 and the second stop structure 333 are both located between the two second extensions (neither of them contacts the second torsion pendulum structure 343 and the fourth torsion pendulum structure 313 in the lateral direction). The second electrode structure 323 is also located directly above the first electrode structure 342 . Thus, the projections of the second electrode structure 323 and the first electrode structure 342 on the surface of the first substrate 100 have an overlapping area, thereby forming the detection capacitor 602 .

[0045] Furthermore, if Fig.14 As shown, a first anchor point 312 is disposed at the bottom of the third torsion pendulum structure 332, and the third torsion pendulum structure 332 is fixed to the first substrate 100 through the first anchor point 312. The first anchor point 312 can serve as a torsion fulcrum of the torsion pendulum rod 601. In this embodiment, the first anchor point 312 is located in the central area of ​​the third torsion pendulum structure 332, so that the torsion pendulum rod 601 can flexibly torsion and swing. In some embodiments, the first anchor point 312 can also be located in other areas of the third torsion pendulum structure 332.

[0046] Since the second electrode structure 323 is located near the torsion rod 601, in this embodiment, the second electrode structure 323 is also fixed to the first substrate 100 through the first anchor point 312, thereby simplifying the structure. Of course, in some embodiments, the second electrode structure 323 can also be fixed to the first substrate 100 through other anchor points.

[0047] Furthermore, a second anchor point 322 is disposed at the bottom of the first stopping structure 352 , and the first stopping structure 352 is fixed to the first substrate 100 via the second anchor point 322 . In this way, the stopping block 603 is fixed to the first substrate 100 .

[0048] Fig.18 and Fig.19 FIG. 1 is a schematic diagram of the movement of the MEMS sensor under the action of acceleration. Fig.14 , Fig.18 and Fig.19 As shown, the two torsion pendulum blocks 604 form a "seesaw". Under the action of acceleration, the torsion pendulum rod 601 twists laterally (the first anchor point 312 serves as a torsion fulcrum), and each torsion pendulum block 604 swings longitudinally (and one torsion pendulum block 604 swings upward, and the other torsion pendulum block 604 swings downward), driving each first electrode structure 342 to tilt longitudinally, and the distance between each first electrode structure 342 and the corresponding second electrode structure 323 changes (one set of distances increases, and the other set of distances decreases), thereby changing the capacitance of each detection capacitor 602 (the capacitance of one detection capacitor 602 increases, and the capacitance of the other detection capacitor 602 decreases). The capacitance of the two detection capacitors 602 changes in opposite directions, and a differential signal is obtained, and the magnitude of the acceleration can be determined by the differential signal.

[0049] When the torsion pendulum block 604 swings, the stopper block 603 can limit the lateral displacement of the torsion pendulum block 604, thereby reducing the risk of adhesion caused by direct contact between the torsion pendulum block 604 and the second electrode structure 323. In some embodiments, the stopper block 603 can also be omitted.

[0050] It can be seen that in this embodiment, since the first electrode structure 342 and the second electrode structure 323 are both arranged above the first substrate 100 and are not in direct contact with the first substrate 100, even if the first substrate 100 is bent and deformed, it will not affect the capacitance of the detection capacitor 602 too much, thereby improving the problem of output signal deviation caused by factors such as packaging stress, and improving the accuracy and stability of detection; and, the torsion pendulum block 604 is connected by two layers of torsion pendulum structure, which increases the mass of the torsion pendulum block 604, improves the sensitivity and reduces the influence of noise.

[0051] Please continue reading Fig.16 and Fig.17 In this embodiment, the area of ​​the first torsion pendulum structure 362 and the area of ​​the second torsion pendulum structure 343 are not much different, the areas of the two first torsion pendulum structures 362 are different, and the areas of the two second torsion pendulum structures 343 are also different. In this way, the masses of the two torsion pendulum blocks 604 are different and asymmetrical, so the sensitivity of detection can be improved. Of course, in some embodiments, the areas of the two first torsion pendulum structures 362 can be the same, and the areas of the two second torsion pendulum structures 343 can also be the same, but different hollow areas can be designed for the two first torsion pendulum structures 362 and the two second torsion pendulum structures 343, and the masses of the two torsion pendulum blocks 604 can also be different, which will not be explained one by one here.

[0052] Further, in this embodiment, a plurality of release holes are provided on the first electrode structure 342, the second electrode structure 323, the first torsion pendulum structure 362 and the second torsion pendulum structure 343. Moreover, the release holes on the first torsion pendulum structure 362 and the second torsion pendulum structure 343 are aligned in the longitudinal direction, and the release holes on the first electrode structure 342 and the corresponding second electrode structure 323 are aligned in the longitudinal direction.

[0053] The maximum lateral width of the release hole may be less than 1 μm, and the shape may be designed according to actual conditions, for example, it may be rectangular or circular, and the present invention does not impose any limitation thereto.

[0054] Please continue reading Fig.14 In this embodiment, the surface of the first substrate 100 is provided with a buried layer 201 and a protective layer 202 from bottom to top, and the buried layer 201 has an alignment mark, which is convenient for providing an alignment function when preparing the patterns of the torsion yaw bar 601, the detection capacitor 602, the stopper block 603 and the torsion yaw block 604. The protective layer 202 is used to protect the buried layer 201 to prevent the buried layer 201 from being damaged during the process of releasing the sacrificial layer.

[0055] Furthermore, the material of the buried layer 201 may be silicon oxide, and the thickness is generally 0.2 μm to 3 μm. The material of the protective layer 202 is preferably a material with high hardness (for example, greater than 8 Mohs), such as silicon nitride, and the thickness is generally 0.2 μm to 1.0 μm, preferably 0.4 μm to 0.8 μm.

[0056] The materials of the torsion wobble 601, detection capacitor 602, stop block 603 and torsion wobble block 604 can be selected from materials with low resistivity (for example, less than 30Ω / □), for example, they can all be polysilicon or doped polysilicon, and the preferred resistivity is less than 10Ω / □.

[0057] Based on this, this embodiment also provides a method for preparing the MEMS sensor. Figure 1 to Figure 14 The schematic diagram of the structure corresponding to the corresponding steps of the method for preparing the MEMS sensor provided in this embodiment. Next, Figure 1 to Figure 14 The preparation method of the MEMS sensor provided in this embodiment is described in detail.

[0058] like Figure 1 As shown, a first substrate 100 is provided, and a buried layer 201 is deposited on the first substrate 100 by methods such as LPCVD, PECVD, thermal oxidation, etc. Then, an alignment mark can be formed in the buried layer 201 by methods such as photolithography and etching.

[0059] like Figure 2As shown, a protective layer 202 is formed on the buried layer 201 by a method such as LPCVD, and the formation temperature of the protective layer 202 can be 570° C. to 630° C. The protective layer 202 can protect the buried layer 201 to prevent the buried layer 201 from being damaged in the subsequent etching step, and can reduce the size of the conductive structure 301 formed subsequently.

[0060] like Figure 3 As shown, a first conductive layer is formed on the protective layer 202 by using a method such as LPCVD and the first conductive layer is patterned to form a plurality of conductive structures 301 .

[0061] The material of the first conductive layer may be polysilicon or doped polysilicon. The formation temperature of the first conductive layer may be 570° C. to 630° C. The thickness may be 0.2 μm to 1.0 μm, and the preferred thickness is 0.4 μm to 0.8 μm.

[0062] like Figure 4 As shown, a first sacrificial layer 401 is formed on the protective layer 202 by a method such as PECVD, and the first sacrificial layer 401 also covers the conductive structure 301. The first sacrificial layer 401 is etched to form a plurality of first through holes 401a penetrating the first sacrificial layer 401, wherein the first through holes 401a are located in the central region of the first substrate 100, and each of the first through holes 401a exposes one of the conductive structures 301, that is, the conductive structures 301 in the central region of the first substrate 100 have the first through holes 401a above them, while the conductive structures 301 in the edge region of the first substrate 100 do not have the first through holes 401a above them.

[0063] The material of the first sacrificial layer 401 can be TEOS, ITO, etc., and the thickness is generally 1 μm to 5 μm, preferably 1.5 μm to 3 μm.

[0064] The shape and size of the first through hole 401 a can be set according to actual needs, and the depth should be sufficient to expose the conductive structure 301 .

[0065] like Figure 5 As shown, a second conductive layer 302 is formed on the first sacrificial layer 401 by using a method such as LPCVD, and the second conductive layer 302 also fills the first through hole 401a. The second conductive layer 302 is etched by using a BOSCH process to form a plurality of release holes 302a penetrating the second conductive layer 302, as shown in FIG. Figure 5As shown, there are a plurality of release holes 302a between two adjacent conductive structures 301. At this time, the portion of the second conductive layer 302 filled in the first through hole 401a and the conductive structure 301 at the bottom thereof constitute a first anchor point 312 and a second anchor point 322.

[0066] The material of the second conductive layer 302 may be polysilicon or doped polysilicon. The formation temperature of the second conductive layer 302 may be 570° C. to 630° C. The thickness is generally 1 μm to 15 μm, preferably 2 μm to 10 μm.

[0067] In some embodiments, a seed layer may be first formed on the first sacrificial layer 401 by using a method such as LPCVD, and then the second conductive layer 302 may be formed by epitaxial polysilicon.

[0068] like Figure 6 As shown, the second sacrificial layer 402 is formed by, for example, LPCVD, and the second sacrificial layer 402 also fills a portion of the depth of the release hole 302a. The second sacrificial layer 402 is etched to form a plurality of second through holes 402a penetrating the second sacrificial layer 402. For example, the second through holes 402a may be located close to each of the conductive structures 301, and there are second through holes 402a between two adjacent conductive structures 301.

[0069] The material of the second sacrificial layer 402 may be TEOS, ITO, etc. The formation temperature of the second sacrificial layer 402 may be 570° C. to 630° C., and the thickness is generally 0.5 μm to 2 μm.

[0070] The shape and size of the second through hole 402 a can be set according to actual needs. For example, the shape of the second through hole 402 a can be square or circular, the size can be 0.2 μm to 0.6 μm, and the depth can expose the second conductive layer 302 .

[0071] like Figure 7 As shown, the second conductive layer 302 below the second through hole 402a is removed by a dry etching process or a wet etching process. After the etching is completed, the second conductive layer 302 is divided into independent patterns, which are the third wiggling structure 332, two first electrode structures 342, two first stop structures 352, two first wiggling structures 362 and two first support structures 372 arranged in sequence from the inside to the outside.

[0072] like Figure 8As shown, the third sacrificial layer 403 is formed by a method such as LPCVD, and the third sacrificial layer 403 covers the second sacrificial layer 402 and covers the opening of the second through hole 402a, forming a relatively flat surface. This process can avoid duplicating the steps of the previous layer when directly forming the third sacrificial layer 403, omitting the chemical mechanical planarization process, reducing costs and improving product reliability compared to traditional processes.

[0073] The material of the third sacrificial layer 403 may be TEOS, ITO, etc. The formation temperature of the third sacrificial layer 403 may be 570° C. to 630° C., and the thickness is generally 0.5 μm to 2 μm.

[0074] like Fig. 9 As shown, the second sacrificial layer 402 and the third sacrificial layer 403 are patterned to form a third through hole 403 a. After patterning, the remaining second sacrificial layer 402 and the third sacrificial layer 403 cover the gaps between the patterns in the second conductive layer 302 and the first electrode structure 342 .

[0075] like Fig.10 As shown, a third conductive layer 303 is formed on the third sacrificial layer 403 by, for example, LPCVD, and the third conductive layer 303 also fills the third through hole 403 a.

[0076] The material of the third conductive layer 303 can be polysilicon or doped polysilicon, and the thickness is generally 5 μm to 50 μm, preferably 10 μm to 30 μm.

[0077] In some embodiments, a seed layer may be first formed on the third sacrificial layer 403 by a method such as LPCVD, and then the third conductive layer 303 may be formed by epitaxial polysilicon. The seed layer thickness is generally 0.1 μm to 1 μm, and the preferred thickness is 0.2 μm to 0.5 μm.

[0078] like Fig.11 As shown, a bonding metal layer is formed on the third conductive layer 303 by sputtering or evaporation process, and the bonding metal layer is patterned to form a bonding structure 500 for subsequent eutectic bonding. The bonding structure 500 is only located above the first supporting structure 372 .

[0079] The thickness of the bonding metal layer may be 1 μm to 2 μm, and the material may be pure aluminum (Al), aluminum silicon (Al-Si (1%)) or a Ti+TiN+Al-Si composite structure film.

[0080] like Fig.12As shown, the third conductive layer 303 is deeply silicon-etched by the BOSCH process to form a fourth through hole 303b, and the fourth through hole 303b exposes the third sacrificial layer 403. After etching, the third conductive layer 303 is divided into independent patterns by the fourth through hole 303b, and these patterns are respectively arranged from the inside to the outside in sequence, the fourth torsion pendulum structure 313, two second electrode structures 323, two second stop structures 333, two second torsion pendulum structures 343 and two second support structures 353. In addition, the second electrode structure 323 and the second torsion pendulum structure 343 also have a plurality of release holes 303a, one of the release holes 303a is located above one of the release holes 302a, and the release holes 303a are aligned with the corresponding release holes 302a in the longitudinal direction.

[0081] like Fig.13 As shown, the third sacrificial layer 403 and the second sacrificial layer 402 are corroded by a method such as hydrofluoric acid vapor fumigation to release the movable structure, so that the first torsion pendulum structure 362 and the corresponding second torsion pendulum structure 343 constitute the torsion pendulum block 604, the third torsion pendulum structure 332 and the fourth torsion pendulum structure 313 constitute the torsion pendulum rod 601, the first electrode structure 342 and the corresponding second electrode structure 323 constitute the detection capacitor 602, the first stop structure 352 and the corresponding second stop structure 333 constitute the stop block 603; the corresponding first supporting structure 372, the second supporting structure 353, the bonding structure 500, the first sacrificial layer 401 and the conductive structure 301 constitute the supporting wall 605.

[0082] like Fig.14 As shown, the second substrate 102 is bonded to the first substrate 100 through the bonding structure 500, so that the detection structure is sealed in the cavity.

[0083] In summary, the MEMS sensor provided in the embodiment of the utility model includes a first substrate and a torsion pendulum rod, and the two opposite sides of the torsion pendulum rod have a detection capacitor and a torsion pendulum block arranged in sequence from the inside to the outside, the first electrode structure and the second electrode structure of the detection capacitor are arranged in sequence from bottom to top on the first substrate, and the first torsion pendulum structure and the second torsion pendulum structure of the torsion pendulum block are arranged in sequence from bottom to top on the first substrate, and only the torsion pendulum rod and the second electrode structure are fixed on the first substrate, the first torsion pendulum structure, the second torsion pendulum structure, the first electrode structure and the torsion pendulum rod are connected to each other, and when acceleration is sensed, the first torsion pendulum structure, the second torsion pendulum structure, the first electrode structure and the torsion pendulum rod can move synchronously to change the capacitance of the detection capacitor to achieve acceleration measurement. Since the first electrode structure and the second electrode structure are both arranged above the first substrate and are not in direct contact with the first substrate, even if the first substrate is bent and deformed, the capacitance of the detection capacitor will not be affected too much, thereby improving the problem of output signal deviation caused by factors such as packaging stress and improving the accuracy and stability of detection; and the torsion pendulum block is connected by two layers of torsion pendulum structure, which increases the mass of the torsion pendulum block, improves the sensitivity and reduces the influence of noise.

[0084] It should be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same or similar parts between the various embodiments can be referred to each other. For the system disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part description.

[0085] It should also be noted that, although the present invention has been disclosed as a preferred embodiment, the above embodiment is not intended to limit the present invention. For any technician familiar with the art, without departing from the scope of the technical solution of the present invention, the above disclosed technical content can be used to make many possible changes and modifications to the technical solution of the present invention, or modified into equivalent embodiments of equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiment based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of protection of the technical solution of the present invention.

[0086] It should also be understood that, unless otherwise specified or indicated, the terms "first", "second", "third", etc. in the specification are merely used to distinguish between the various components, elements, steps, etc. in the specification, and are not used to indicate the logical relationship or sequential relationship between the various components, elements, steps, etc.

[0087] It should also be recognized that the terms described herein are only used to describe specific embodiments and are not used to limit the scope of the utility model. It must be noted that the singular forms "one" and "a kind" used herein and in the appended claims include plural references unless the context clearly indicates the opposite meaning. For example, a reference to "a step" or "a device" means a reference to one or more steps or devices, and may include secondary steps and secondary devices. All conjunctions used should be understood in the broadest sense. And, the word "or" should be understood to have a logical "or" definition, rather than a logical "exclusive or" definition, unless the context clearly indicates the opposite meaning. In addition, the implementation of the method and / or device in the embodiment of the utility model may include performing the selected task manually, automatically, or in combination.

Claims

1. A MEMS sensor, characterized in that: It comprises a first substrate and a torsion yaw rod, wherein two opposite sides of the torsion yaw rod are provided with a detection capacitor and a torsion yaw block arranged in sequence from the inside to the outside; The detection capacitor includes a first electrode structure and a second electrode structure sequentially arranged on the first substrate from bottom to top, the torsion pendulum block includes a first torsion pendulum structure and a second torsion pendulum structure sequentially arranged on the first substrate from bottom to top, and the torsion pendulum rod and the second electrode structure are fixed on the first substrate; and, The first torsion pendulum structure, the second torsion pendulum structure, the first electrode structure and the torsion pendulum rod are connected to each other to move synchronously, and are isolated from the second electrode structure.

2. The MEMS sensor according to claim 1, characterized in that: The MEMS sensor is an accelerometer.

3. The MEMS sensor according to claim 2, characterized in that: Under the action of acceleration, the MEMS sensor twists the torsion pendulum laterally and each torsion pendulum swings longitudinally, so that each first electrode structure tilts longitudinally, changing the distance between each first electrode structure and the corresponding second electrode structure, so as to change the capacitance of each detection capacitor.

4. The MEMS sensor according to claim 3, characterized in that: The two torsion pendulum blocks swing in opposite directions, so that the capacitances of the two detection capacitors change in opposite directions, and a differential signal is obtained.

5. The MEMS sensor according to any one of claims 1 to 4, characterized in that: The torsion pendulum rod includes a third torsion pendulum structure and a fourth torsion pendulum structure which are arranged on the first substrate from bottom to top in sequence, the third torsion pendulum structure and the fourth torsion pendulum structure are connected to each other, the first electrode structure, the first torsion pendulum structure and the third torsion pendulum structure are located on the same layer, and the second electrode structure, the second torsion pendulum structure and the fourth torsion pendulum structure are located on the same layer.

6. The MEMS sensor according to claim 5, characterized in that: A first anchor point is disposed at the bottom of the third torsion pendulum structure, and the third torsion pendulum structure and the second electrode structure are both fixed on the first substrate through the first anchor point.

7. The MEMS sensor according to claim 6, characterized in that: The first anchor point is located in a central area of ​​the third torsion pendulum structure.

8. The MEMS sensor according to claim 5, characterized in that: The third torsion pendulum structure and the fourth torsion pendulum structure are both in strip shape, the first torsion pendulum structure is connected to the first electrode structure as a whole, both ends of the first electrode structure have a first extension part, and the first electrode structure is connected to both ends of the third torsion pendulum structure through the first extension part; and Both ends of the second torsion pendulum structure have second extension parts, and the second torsion pendulum structure is connected to both ends of the fourth torsion pendulum structure through the second extension parts. The second electrode structure is located between the two second extension parts and directly above the first electrode structure.

9. The MEMS sensor according to claim 5, characterized in that: A stop block is further provided between the torsion pendulum block and the corresponding detection capacitor, and the stop block is fixed on the first substrate.

10. The MEMS sensor according to claim 9, characterized in that: The stopping block includes a first stopping structure and a second stopping structure which are sequentially arranged on the first substrate from bottom to top, and the stopping structure and the second stopping structure are connected to each other; and, The first stop structure is located between the first electrode structure and the first torsion pendulum structure, and is isolated from the first electrode structure and the first torsion pendulum structure. The second stop structure is located between the second electrode structure and the second torsion pendulum structure, and is isolated from the second electrode structure and the second torsion pendulum structure.

11. The MEMS sensor according to claim 10, characterized in that: A second anchor point is provided at the bottom of the first stopping structure, and the first stopping structure is fixed on the first substrate through the second anchor point.

12. The MEMS sensor according to claim 5, characterized in that: The first electrode structure, the second electrode structure, the first torsion pendulum structure and the second torsion pendulum structure all have a plurality of release holes.

13. The MEMS sensor according to any one of claims 1 to 4, characterized in that: The masses of the two torsion pendulum masses are different.

14. The MEMS sensor according to claim 12, wherein: The first torsion pendulum structure is aligned with the release hole on the corresponding second torsion pendulum structure in the longitudinal direction; and / or, the first electrode structure is aligned with the release hole on the corresponding second electrode structure in the longitudinal direction.

15. The MEMS sensor according to claim 1, wherein: Also includes: a second substrate, arranged opposite to the first substrate; as well as, The supporting wall is located between the first substrate and the second substrate, and together with the first substrate and the second substrate, encloses a closed cavity. The torsion pendulum rod, the detection capacitor and the torsion pendulum block are all located in the cavity.

16. The MEMS sensor according to claim 15, characterized in that: Also includes: A bonding structure is located between the supporting wall and the second substrate.

17. The MEMS sensor according to claim 1, wherein: Also includes: A buried layer, located on the first substrate, wherein the buried layer has an alignment mark; as well as, The protection layer is located on the buried layer.

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