CN214122269U

CN214122269U - Micro-electromechanical sensor

Info

Publication number: CN214122269U
Application number: CN202022170714.0U
Authority: CN
Inventors: 季锋; 闻永祥; 刘琛; 贺锦
Original assignee: Hangzhou Shilan Jixin Microelectronics Co ltd; Hangzhou Silan Integrated Circuit Co Ltd
Current assignee: Hangzhou Shilan Jixin Microelectronics Co ltd; Hangzhou Silan Integrated Circuit Co Ltd
Priority date: 2020-09-28
Filing date: 2020-09-28
Publication date: 2021-09-03
Anticipated expiration: 2030-09-28

Abstract

Disclosed is a microelectromechanical sensor, the microelectromechanical sensor comprising: a buried layer including a plurality of first raised regions; a plurality of detection electrodes and a plurality of wiring electrodes on the buried layer, the plurality of detection electrodes covering the plurality of first elevated regions, respectively; the torsional swing arm is positioned above the plurality of detection electrodes and the plurality of wiring electrodes, and the torsional swing arm, the plurality of detection electrodes and the plurality of wiring electrodes are not contacted with each other; the torsional pendulum is positioned above the torsional pendulum arm, the movable torsional pendulum blocks are connected with the torsional pendulum through the torsional pendulum arm, and the movable torsional pendulum blocks and the torsional pendulum arm form a movable structure; a plurality of fixed electrodes positioned above the torsion pendulum arm; the buried layer is provided with a supporting wall and a protective wall, the supporting wall and the protective wall are arranged on the buried layer to form a cavity, and the movable structure, the torsion pendulum, the detection electrodes, the wiring electrodes and the fixed electrodes are arranged in the cavity. The embodiment of the utility model provides an improved micro-electromechanical sensor's sensitivity, improved the cracked problem of movable structure under the impact.

Description

Micro-electromechanical sensor

Technical Field

The utility model relates to a MEMS technical field, in particular to micro-electromechanical system sensor.

Background

Micro-electromechanical sensors (MEMS sensors) have received much attention since their incessance because of their small size, low cost, high reliability, low power consumption, strong ability to resist harsh environments, easy integration, etc. Wherein, the sensitive structure of the MEMS Z-axis accelerometer is a torsional pendulum type accelerometer. The existing method for improving the sensitivity of the torsional pendulum type accelerometer is mainly to increase the area of the accelerometer, so that the sensitivity of the accelerometer can be improved by increasing the area under the condition of small mechanical sensitivity. But increases the area of the torsional pendulum accelerometer, increasing manufacturing costs. In addition, when the torsional pendulum type accelerometer is operated, a movable structure of the accelerometer is deviated in a vertical direction due to a sudden overload, and the movable structure may be broken under an impact. Therefore, it is desirable to provide a micro-electromechanical sensor, which can improve the sensitivity of the micro-electromechanical sensor without increasing the area of the micro-electromechanical sensor, and can solve the problem of the movable structure of the micro-electromechanical sensor breaking under the impact.

Disclosure of Invention

In view of the above, the present invention is directed to a micro-electromechanical sensor, which improves the sensitivity of the micro-electromechanical sensor without increasing the area of the micro-electromechanical sensor, and improves the problem of the movable structure of the micro-electromechanical sensor breaking under impact.

According to the utility model discloses an aspect provides a micro-electromechanical sensor, includes:

a substrate;

the buried layer is positioned on the substrate and comprises a plurality of first heightened areas, a plurality of detection electrodes and a plurality of wiring electrodes are arranged on the buried layer, and the detection electrodes respectively cover the first heightened areas;

a torsion swing arm positioned above the plurality of detection electrodes and the plurality of wiring electrodes, the torsion swing arm being not in contact with the plurality of detection electrodes and the plurality of wiring electrodes;

the torsional pendulum and the movable torsional pendulum blocks are positioned above the torsional pendulum arm, the movable torsional pendulum blocks are connected with the torsional pendulum through the torsional pendulum arm, and the movable torsional pendulum blocks and the torsional pendulum arm form a movable structure;

a plurality of fixed electrodes located above the torsion pendulum arm;

support wall and protection wall, the support wall is located on the buried layer, the protection wall is located on the support wall, the support wall with the protection wall encloses into the cavity, movable structure the pendulum the plurality of detection electrode a plurality of wiring electrodes with a plurality of fixed electrodes are located in the cavity.

Optionally, the torsion pendulum arm comprises: a first braking structure that provides braking in a left-right direction for the movable structure.

Optionally, the torsion pendulum arm comprises: a first braking structure that provides braking in an upward direction for the movable structure.

Optionally, the torsion pendulum arm comprises: a first braking structure that provides braking in a left-right direction and an upward direction for the movable structure.

Optionally, the micro-electromechanical sensor further comprises:

a second detent structure on the substrate, the second detent structure providing downward direction detent for the movable structure.

Optionally, the torsion pendulum arm comprises: a first braking structure, the micro-electromechanical sensor further comprising: a second braking structure located on the substrate,

the first braking structure and the second braking structure provide braking for the movable structure in the vertical and horizontal directions.

Optionally, the first braking structure comprises: the first brake spring is positioned at the first end of the torsion swing arm, and the second brake spring is positioned at the second end of the torsion swing arm.

Optionally, the buried layer further comprises: a plurality of first bumps, the plurality of wiring electrodes covering the plurality of first bumps, respectively.

Optionally, the micro-electromechanical sensor further comprises: a plurality of second protrusions on the substrate, the plurality of first protrusions covering the plurality of second protrusions, respectively.

Optionally, the second braking structure comprises: a plurality of bump structures including the plurality of second bumps, the plurality of first bumps corresponding to the plurality of second bumps, and the plurality of wiring electrodes.

Optionally, the micro-electromechanical sensor further comprises: a plurality of second raised areas on the substrate, the plurality of first raised areas respectively overlying the plurality of second raised areas.

Optionally, the plurality of detection electrodes comprises: a first detection electrode and a second detection electrode, the plurality of fixed electrodes including: a first fixed electrode and a second fixed electrode positioned at both sides of the torsion pendulum,

the first detection electrode and the second detection electrode respectively form differential capacitance with the swing arm, and the first fixed electrode and the second fixed electrode respectively form differential capacitance with the swing arm.

Optionally, the plurality of movable torsion pendulum blocks comprises: the first movable torsion pendulum block and the second movable torsion pendulum block are positioned on two sides of the torsion pendulum, and the mass of the first movable torsion pendulum block and the mass of the second movable torsion pendulum block are different.

Optionally, the first movable torsion pendulum mass comprises a plurality of sub-movable torsion pendulum masses.

Optionally, the first detent structure of the swing arm is located below the protective wall.

Optionally, the distance between the inner side wall of the protection wall and the plurality of movable torsion pendulum blocks is greater than the distance between the first braking structure and the inner side wall of the support wall.

Optionally, the support wall comprises: a first sacrificial layer, a second sacrificial layer, and a portion of the first structural layer.

Optionally, the material of the first sacrificial layer includes: silicon dioxide.

Optionally, the thickness of the first sacrificial layer is 0.5 to 2 um.

Optionally, the material of the second sacrificial layer includes: silicon dioxide.

Optionally, the thickness of the second sacrificial layer is 0.5 to 2 um.

Optionally, the microelectromechanical sensor includes: a torsional pendulum accelerometer.

According to the micro-electromechanical sensor provided by the embodiment of the utility model, the buried layer is provided with a plurality of detection electrodes and a plurality of wiring electrodes, the torsional swing arm is positioned above the detection electrodes and the wiring electrodes, and the torsional swing arm, the detection electrodes and the wiring electrodes are not contacted with each other; the torsional pendulum and the movable torsional pendulum blocks are positioned above the torsional pendulum arm, the movable torsional pendulum blocks are connected with the torsional pendulum through the torsional pendulum arm, and the movable torsional pendulum blocks and the torsional pendulum arm form a movable structure; the plurality of fixed electrodes are positioned above the torsional pendulum arm; the supporting wall is located on the buried layer, the protection wall is located on the supporting wall, a cavity is defined by the supporting wall and the protection wall, and the movable structure, the torsion pendulum, the plurality of detection electrodes, the plurality of wiring electrodes and the plurality of fixed electrodes are located in the cavity. The first fixed electrode and the torsion swing arm form a first variable capacitor, the second fixed electrode and the torsion swing arm form a second variable capacitor, the first detection electrode and the torsion swing arm form a third variable capacitor, and the second detection electrode and the torsion swing arm form a fourth variable capacitor. The first variable capacitor and the second variable capacitor form a pair of differential capacitors. The third variable capacitor and the fourth variable capacitor form a pair of differential capacitors. The acceleration value can be obtained by measuring the change of the two pairs of differential capacitors, and the sensitivity of the micro-electromechanical sensor is improved while the area of the micro-electromechanical sensor is not increased. In addition, the two first heightening areas respectively heighten the heights of the first detection electrode and the second detection electrode in a limiting manner, the distance between the first detection electrode and the torsional pendulum arm and the distance between the second detection electrode and the torsional pendulum arm are reduced, and then the capacitance detection sensitivity of the third variable capacitor and the capacitance detection sensitivity of the fourth variable capacitor are improved under the condition that the movable range of the movable structure of the micro-electromechanical sensor is unchanged, so that the sensitivity of the accelerometer is improved.

The plurality of second bumps, the corresponding plurality of first bumps, and the plurality of first wiring electrodes form a plurality of bump structures, and the plurality of bump structures form a second stopper structure. The second braking structure is located below the torsional pendulum arm, and when the movable structure moves downwards, the second braking structure blocks the torsional pendulum arm from continuing to move downwards, so that the second braking structure limits the downward movement range of the movable structure. The first braking structure of the twisting swing arm is located below the protective wall, when the movable structure moves upwards, the first braking structure blocks the twisting swing arm to continue moving upwards, and the first braking structure limits the upward movement range of the movable structure. The distance between the inner side wall of the protection wall and the movable torsion and swing block is larger than the distance between the first braking structure and the inner side wall of the support wall, when the movable structure moves leftwards or rightwards, the first braking structure firstly touches the inner side wall of the support wall to prevent the movable torsion and swing block from touching the inner side wall of the protection wall, and the first braking structure limits the leftward or rightward moving range of the movable structure. The first braking structure and the second braking structure are used as mechanical stops, so that the transverse movement and the longitudinal movement of the movable structure are limited within a certain range, the problem that the movable structure is damaged under certain mechanical impact is solved, and the reliability of the micro-electromechanical sensor is improved.

Drawings

The above and other objects, features and advantages of the present invention will become more apparent from the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

figure 1 shows a schematic view of a conventional micro-electromechanical sensor;

figure 2 shows a top view of the conventional mems shown in figure 1;

figure 3 shows a schematic structural view of a micro-electromechanical sensor according to an embodiment of the present invention;

figure 4 shows a top view of the mems sensor of figure 3 in accordance with an embodiment of the invention;

figures 5a to 5h show cross-sectional views of different stages of a method of manufacturing a micro-electromechanical sensor according to an embodiment of the invention.

Detailed Description

Various embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Like elements in the various figures are denoted by the same or similar reference numerals. For purposes of clarity, the various features in the drawings are not necessarily drawn to scale.

The following detailed description of the embodiments of the present invention is provided with reference to the accompanying drawings and examples.

Figure 1 shows a schematic diagram of a conventional mems. Figure 2 shows a top view of the conventional mems shown in figure 1. The conventional mems sensor 100 shown in fig. 1 and 2 is specifically a torsional pendulum type acceleration sensor. As shown in fig. 1 and 2, the micro-electromechanical sensor 100 includes: a substrate 110; a buried layer 120 located on the substrate 110; a first detection electrode 131 and a second detection electrode 132 on the buried layer 120; a support wall 141 on the buried layer 120; a protective wall 151 on the support wall 141, a first movable electrode 152, a second movable electrode 153, and a torsion pendulum 154. The support wall 141 and the protection wall 151 enclose a cavity 160. The first detection electrode 131, the second detection electrode 132, the first movable electrode 152, the second movable electrode 153, and the torsion pendulum 154 are located in the cavity 160. The first movable electrode 152 and the first detection electrode 131 form a first variable capacitance, and the second movable electrode 153 and the second detection electrode 132 form a second variable capacitance. The first variable capacitor and the second variable capacitor form a pair of differential capacitors. The first movable electrode 152 and the second movable electrode 153 form a movable structure of the micro-electromechanical sensor 100. When acceleration perpendicular to the first movable electrode 152 and the second movable electrode 153 is present, the first movable electrode 152 and the second movable electrode 153 are twisted around the torsion pendulum 154, and the capacitance of the pair of differential capacitances, i.e., the first variable capacitance and the second variable capacitance, is changed, and the acceleration value can be obtained by measuring the capacitance change of the first variable capacitance and the second variable capacitance. The conventional mems sensor 100 shown in fig. 1 and 2 includes two variable capacitors, and the method for improving the sensitivity is mainly to increase the area of the mems, so that the sensitivity of the mems can be improved by increasing the area in the case of small mechanical sensitivity. But the area of the micro-electromechanical sensor is increased, and the manufacturing cost of the micro-electromechanical sensor is increased. In addition, when the conventional mems sensor 100 shown in fig. 1 and 2 operates, a sudden overload may cause the movable structure of the mems sensor 100 to shift in the vertical direction, and the movable structure may be easily broken under an impact.

In order to solve the above problem, an embodiment of the present invention provides a micro electromechanical sensor, and the structure of the micro electromechanical sensor in the embodiment of the present invention is described in detail below with reference to the accompanying drawings.

Figure 3 shows a schematic structural diagram of a micro-electromechanical sensor according to an embodiment of the present invention. Figure 4 shows a top view of the mems shown in figure 3 in accordance with an embodiment of the present invention. Mems 200 shown in fig. 3 and 4 is specifically a torsional pendulum type acceleration sensor. As shown in fig. 3 and 4, mems 200 includes: substrate 210, the material of substrate 210 comprising: monocrystalline silicon, the crystal orientation of monocrystalline silicon is <100 >; a buried layer 230 on the substrate 210, the buried layer 230 including a first protrusion 231, a first protrusion 232, a first raised region 233, and a first raised region 234; the material of the buried layer 230 includes: silicon dioxide, 0.5 to 5 um thick. Preferably, the buried layer 230 has a thickness of 1.5 to 2.5 um. The materials of the first protrusion 231, the first protrusion 232, the first elevated region 233, and the first elevated region 234 include: silicon dioxide, thickness 0.1 to 2 um. Preferably, the thickness of the first protrusion 231, the first protrusion 232, the first elevated region 233, and the first elevated region 234 is 0.3 to 1 um. In some embodiments, the microelectromechanical sensor 200 also includes a second protrusion 221, a second protrusion 222, a second raised area 223, and a second raised area 224 on the substrate 210, and the materials of the second protrusion 221, the second protrusion 222, the second raised area 223, and the second raised area 224 include: silicon, silicon dioxide, polysilicon and silicon nitride, with a thickness of 0.1 to 2 um. The first protrusion 231 covers the second protrusion 221, the first protrusion 232 covers the second protrusion 222, the first elevated area 233 covers the second elevated area 223, and the first elevated area 234 covers the second elevated area 224. The second raised area 223 and the second raised area 224 definitively raise the height of the first raised area 233 and the first raised area 234, respectively. A first detection electrode 243, a second detection electrode 244, a first wiring electrode 241, and a second wiring electrode 242 on the buried layer 230, the first wiring electrode 241 covering the first protrusion 231 to form a protrusion, the second wiring electrode 242 covering the first protrusion 232 to form a protrusion, the first detection electrode 243 covering the first elevated region 233, the second detection electrode 244 covering the first elevated region 234; the first

elevated regions

233 and 234 definitively elevate the heights of the first and

second detection electrodes

243 and 244, respectively. The materials of the first detection electrode 243, the second detection electrode 244, the first wiring electrode 241, and the second wiring electrode 242 include: the polysilicon has a thickness of 0.1 to 1 um and a resistivity of less than 30 Ω · cm. Preferably, the first detection electrode 243, the second detection electrode 244, the first wiring electrode 241, and the second wiring electrode 242 have a thickness of 0.3 to 0.6 um and a resistivity of less than 10 Ω · cm. A torsion pendulum arm 261 positioned above the first detection electrode 243, the second detection electrode 244, the first wiring electrode 241, and the second wiring electrode 242, the first detection electrode 243, the second detection electrode 244, the first wiring electrode 241, the second wiring electrode 242, and the torsion pendulum arm 261 not contacting each other; the torsional pendulum 284, the first movable torsional pendulum block 281 and the second movable torsional pendulum block 282 are arranged on two sides of the torsional pendulum 284, the first movable torsional pendulum block 281 and the second movable torsional pendulum block 282 are arranged above the torsional pendulum 261, the first movable torsional pendulum block 281 and the second movable torsional pendulum block 282 are connected with the torsional pendulum 284 through the torsional pendulum arm 261, and the first movable torsional pendulum block 281, the second movable torsional pendulum block 282 and the torsional pendulum arm 261 form a movable structure; the first movable torsion pendulum block 281 and the second movable torsion pendulum block 282 have different masses. Specifically, the first movable torsion pendulum block 281 includes a plurality of sub movable torsion pendulum blocks 283.

Mems 200 further includes: a first fixed electrode 285 and a second fixed electrode 286 on both sides of the torsion pendulum 284, the first fixed electrode 285 and the second fixed electrode 286 being positioned above the torsion pendulum arm 261; a support wall 290 and a protection wall 287, the support wall 290 being located on the buried layer 230, the protection wall 287 being located on the support wall 290, the support wall 290 and the protection wall 287 enclosing a cavity 291, and the movable structure, the torsion pendulum 284, the first detection electrode 243, the second detection electrode 244, the first wiring electrode 241, the second wiring electrode 242, the first fixed electrode 285, and the second fixed electrode 286 being located in the cavity 291. The materials of first movable torsion pendulum block 281, second movable torsion pendulum block 282, torsion pendulum 284, first fixed electrode 285, second fixed electrode 286, and protective wall 287 include: the thickness of the polycrystalline silicon is 10-50 um, and the resistivity is less than 30 omega cm. Preferably, the thickness of first movable torsion pendulum block 281, second movable torsion pendulum block 282, torsion pendulum 284, first fixed electrode 285, second fixed electrode 286, and protective wall 287 is 15 to 25 um, and the resistivity is less than 10 Ω · cm.

The torsion swing arm 261 includes: a first braking structure. The first detent structure of the torsional swing arm 261 is located below the protective wall 287. The first braking structure provides braking in a left-right direction and/or an upward direction for the movable structure. The first braking structure includes: a first brake spring 263 located at a first end of the torsion swing arm 261 and a second brake spring 264 located at a second end of the torsion swing arm 261. The distance between the inner side wall of the protection wall 287 and the first movable torsion pendulum block 281 is larger than the distance between the first brake spring 263 and the inner side wall of the support wall 290. The distance between the inner wall of the protection wall 287 and the second movable torsion pendulum block 282 is larger than the distance between the second brake spring 264 and the inner wall of the support wall 290. Mems 200 further includes: a second braking structure, the second braking structure comprising: the first wiring electrode 241, the first bump 231, and the second bump 221 form a first bump structure, and the second wiring electrode 242, the first bump 232, and the second bump 222 form a second bump structure. The second braking structure provides braking in a downward direction for the movable structure.

The support wall 290 includes: a first sacrificial layer 250, a second sacrificial layer 270, and a portion of the first structural layer 260. The first sacrificial layer 250 is located on the buried layer 230, the first structural layer 260 is located on the first sacrificial layer 250, and the second sacrificial layer 270 is located on the first structural layer 260. The material of the first sacrificial layer 250 includes: silicon dioxide, 0.5 to 2 um thick. Alternative materials for the first sacrificial layer 250 also include: SiO prepared from tetraethyl orthosilicate (TEOS)₂Low temperature chemical vapor deposition of SiO₂(LTO). Preferably, the thickness of the first sacrificial layer 250 is 0.7 to 1.5 um. The material of the first structure layer 260 includes: the thickness of the polysilicon is 0.5 to 5 um, and the resistivity is less than 30 omega cm. Preferably, the first structural layer 260 has a thickness of 0.75 to 2 um and a resistivity of less than 10 Ω · cm. The material of the second sacrificial layer 270 includes: silicon dioxide, 0.5 to 2 um thick. Preferably, the thickness of the second sacrificial layer 270 is 0.7 to 1.5 um. Alternative materials for the second sacrificial layer 270 also include: SiO prepared from tetraethyl orthosilicate (TEOS)₂Low temperature chemical vapor deposition of SiO₂(LTO)。

The first brake structure (the first brake spring 263 and the second brake spring 264) of the torsion swing arm 261 is located below the protection wall 287, and when the movable structure moves upward, the first brake spring 263 and the second brake spring 264 block the torsion swing arm 261 from further moving upward, and the first brake spring 263 and the second brake spring 264 limit the upward movement range of the movable structure. The second detent structure (the first protruding structure and the second protruding structure) is located below the torsion swing arm 261, and when the movable structure moves downward, the second detent structure blocks the torsion swing arm 261 from continuing to move downward, and therefore, the second detent structure limits the downward movement range of the movable structure. The distance between the inner side wall of the protection wall 287 and the movable torsion pendulum block (the first movable torsion pendulum block 281 and the second movable torsion pendulum block 282) is greater than the distance between the first brake structure (the first brake spring 263 and the second brake spring 264) and the inner side wall of the support wall 290, when the movable structure moves leftward, the first brake spring 263 first contacts with the inner side wall of the support wall 290, the first movable torsion pendulum block 281 is prevented from contacting with the inner side wall of the protection wall 287, and the first brake structure (the first brake spring 263) limits the leftward movement range of the movable structure. When the movable structure moves rightward, the second brake spring 264 first contacts the inner wall of the support wall 290, and prevents the second movable torsion pendulum block 282 from contacting the inner wall of the protective wall 287, and the first brake structure (the second brake spring 264) limits the rightward movement range of the movable structure. The first brake spring 263 and the second brake spring 264 are made of soft materials and have elasticity, and the first brake spring 263 and the second brake spring 264 play a role in buffering when the movable structure collides up and down and moves left and right, so that the phenomenon that the movable structure is broken under impact is improved, and the reliability of the micro-electromechanical sensor 200 is improved.

The first fixed electrode 285 and the torsion arm 261 form a first variable capacitance, the second fixed electrode 286 and the torsion arm 261 form a second variable capacitance, the first detection electrode 243 and the torsion arm 261 form a third variable capacitance, and the second detection electrode 244 and the torsion arm 261 form a fourth variable capacitance. The first variable capacitor and the second variable capacitor form a pair of differential capacitors. The third variable capacitor and the fourth variable capacitor form a pair of differential capacitors. When acceleration perpendicular to the movable structure exists, the first movable torsion pendulum block 281 and the second movable torsion pendulum block 282 are twisted around the torsion pendulum 284, so that a pair of differential capacitances, namely the first variable capacitance and the second variable capacitance, is changed, a pair of differential capacitances, namely the third variable capacitance and the fourth variable capacitance, is changed, and the acceleration value of the micro-electromechanical sensor 200 can be obtained by measuring the change from the first variable capacitance to the fourth variable capacitance. The micro-electromechanical sensor 200 includes four variable capacitances (two pairs of differential capacitances), and the acceleration value is detected by changes in the four variable capacitances (two pairs of differential capacitances), which improves the sensitivity of the micro-electromechanical sensor 200.

It is easy to understand that, in the case that the micro electromechanical sensor 200 does not have the second protrusion 221, the second protrusion 222, the second increased region 223, the second increased region 224, the first protrusion 231, the first protrusion 232, the first increased region 233, and the first increased region 234, the micro electromechanical sensor 200 of the embodiment of the present invention can also improve the capacitance detection sensitivity of the third variable capacitance formed by the first detection electrode 243 and the torsion pendulum arm 261 and the capacitance detection sensitivity of the fourth variable capacitance formed by the second detection electrode 244 and the torsion pendulum arm 261 by increasing the heights of the first detection electrode 243 and the second detection electrode 244.

It should be noted that, in the case that the micro electromechanical sensor 200 does not include the second protrusion 221, the second protrusion 222, the second height increasing region 223, the second height increasing region 224, the first protrusion 231, the first protrusion 232, the first height increasing region 233, and the first height increasing region 234, the micro electromechanical sensor 200 according to the embodiment of the present invention may further reduce the distance between the first detection electrode 243 and the torsion pendulum arm 261 and the distance between the second detection electrode 244 and the torsion pendulum arm 261 by reducing the height of the first sacrificial layer 250, so as to improve the capacitance detection sensitivity of the third variable capacitance formed by the first detection electrode 243 and the torsion pendulum arm 261 and the capacitance detection sensitivity of the fourth variable capacitance formed by the second detection electrode 244 and the torsion pendulum arm 261. However, the reduction in height of first sacrificial layer 250 reduces the range of motion of the movable structure of mems 200.

The embodiment of the utility model provides an in, the second increases regional 223 and the second increases regional 224 and has increased the height that first increase regional 233 and first increase regional 234 in a definite way respectively, first increase regional 233 and first increase regional 234 respectively the limit have increased the height of first detection electrode 243 and second detection electrode 244, the distance between first detection electrode 243 and the swing arm 261 and the distance between second detection electrode 244 and the swing arm 261 have been reduced, and then the capacitance detection sensitivity of the third variable capacitance that first detection electrode 243 and swing arm 261 formed and the capacitance detection sensitivity of the fourth variable capacitance that second detection electrode 244 and swing arm 261 formed have been improved, thereby the sensitivity of micro electromechanical sensor 200 has been improved under the unchangeable condition of the home range of the movable structure of micro electromechanical sensor 200.

Figures 5a to 5h show cross-sectional views of different stages of a method of manufacturing a micro-electromechanical sensor according to an embodiment of the invention. Referring to fig. 5 a-5 h, a method of fabricating mems 200 includes the following steps.

As shown in fig. 5a, a substrate 210 is provided, and a layer of thin film material including silicon, silicon dioxide, polysilicon and silicon nitride is formed on the substrate 210 by a conventional semiconductor processing method such as thermal oxidation or Low Pressure Chemical Vapor Deposition (LPCVD) or Plasma Enhanced Chemical Vapor Deposition (PECVD). The thin film material is then patterned by conventional semiconductor processing methods to form second protrusions 221, second protrusions 222, second elevated regions 223, and second elevated regions 224 on the substrate 210. The material of the substrate 210 includes: and single crystal silicon having a crystal orientation of <100> and a thickness of the

second protrusions

221, 222, 223, and 224 of 0.1 to 2 um. Preferably, the thickness of the

second protrusions

221, 222, 223, and 224 is 0.3 to 1 um. It is readily understood that embodiments of the present invention may pattern the substrate 210 by conventional semiconductor processing methods to form the second bump 221, the second bump 222, the second raised region 223 and the second raised region 224.

As shown in fig. 5b, a buried layer 230 is formed on the second bump 221, the second bump 222, the second elevated region 223 and the second elevated region 224 by a conventional semiconductor process method such as thermal oxidation or Low Pressure Chemical Vapor Deposition (LPCVD) or Plasma Enhanced Chemical Vapor Deposition (PECVD). The buried layer 230 forms a first bump 231 covering the second bump 221, a first bump 232 covering the second bump 222, a first raised region 233 covering the second raised region 223, and a first raised region 234 covering the second raised region 224. The second raised area 223 and the second raised area 224 definitively raise the height of the first raised area 233 and the first raised area 234, respectively. The material of the buried layer 230 includes: silicon dioxide, the buried layer 230 is 0.5 to 5 um thick. Preferably, the buried layer 230 has a thickness of 1.5 to 2.5 um. The materials of the

first protrusions

231, 232, 233 and 234 include: the thickness of the silicon dioxide, the first protrusion 231, the first protrusion 232, the first elevated region 233, and the first elevated region 234 is 0.1 to 2 um. Preferably, the thickness of the first protrusion 231, the first protrusion 232, the first elevated region 233, and the first elevated region 234 is 0.3 to 1 um.

It is to be understood that forming the second bump 221, the second bump 222, the second raised region 223 and the second raised region 224 on the substrate 210 is an optional step, and the first bump 231, the first bump 232, the first raised region 233 and the first raised region 234 on the buried layer 230 and the buried layer 230 may be formed directly on the substrate in the embodiment of the present invention. The specific steps can be as follows: a substrate 210 is provided, a buried layer of material is formed on the substrate 210 by a conventional semiconductor process such as thermal oxidation or Low Pressure Chemical Vapor Deposition (LPCVD) or Plasma Enhanced Chemical Vapor Deposition (PECVD), and then the buried layer of material is patterned by the conventional semiconductor process to form first protrusions 231, first protrusions 232, first raised regions 233, and first raised regions 234 on the buried layer 230.

As shown in fig. 5c, a wiring layer material is deposited on the buried layer 230 by a conventional semiconductor process such as Low Pressure Chemical Vapor Deposition (LPCVD), and then patterned by photolithography and etching to form a wiring layer 240. The wiring layer 240 includes a first detection electrode 243, a second detection electrode 244, a first wiring electrode 241, and a second wiring electrode 242, the first wiring electrode 241 covers the first bump 231 to form a bump, the second wiring electrode 242 covers the first bump 232 to form a bump, the first detection electrode 243 covers the first elevated region 233, and the second detection electrode 244 covers the first elevated region 234; the first

elevated regions

233 and 234 definitively elevate the heights of the first and

second detection electrodes

243 and 244, respectively. A first bump structure formed by the second bump 221, the first bump 231, and the first wiring electrode 241, and a second bump structure formed by the second bump 222, the first bump 232, and the second wiring electrode 242. The first and second raised structures act as a second braking structure for mems 200, which provides braking in a downward direction of motion for a movable structure of mems 200 formed in a subsequent process. The material of wiring layer 240 includes: the polysilicon has a thickness of 0.1 to 1 um and a resistivity of less than 30 Ω · cm. Preferably, the wiring layer 240 has a thickness of 0.3 to 0.6 um and a resistivity of less than 10 Ω · cm. It should be noted that the wiring layer 240 may have a rough surface, which can prevent the first wiring electrode 241 and the second wiring electrode 242 from adhering to the torsion pendulum arm 261 to be formed later.

As shown in fig. 5d, a layer of first sacrificial material is deposited on the wiring layer 240 by a conventional semiconductor process such as thermal oxidation or Low Pressure Chemical Vapor Deposition (LPCVD) or Plasma Enhanced Chemical Vapor Deposition (PECVD), the first sacrificial material is planarized by a Chemical Mechanical Polishing (CMP) process, and then patterned by photolithography and etching to form a first sacrificial layer 250. The first sacrificial layer 250 covers the first detection electrode 243, the second detection electrode 244, the first wiring electrode 241, the second wiring electrode 242, and the exposed buried layer 230. The first sacrificial layer 250 includes: a third projection 251, a fourth projection 252, and a fourth projection 253. The fourth protrusion 252 and the fourth protrusion 253 control a distance between the torsion pendulum arm 261 and the support wall 290 formed in a subsequent process. The third protrusions 251 control the shapes of both ends of the torsion pendulum arm 261 formed in the subsequent process. The material of the first sacrificial layer 250 includes: silicon dioxide, 0.5 to 2 um thick. Alternative materials for the first sacrificial layer 250 also include: SiO prepared from tetraethyl orthosilicate (TEOS)₂Low temperature chemical vapor deposition of SiO₂(LTO). Preferably, the thickness of the first sacrificial layer 250 is 0.7 to 1.5 um.

As shown in fig. 5e, a layer of first structural layer material is deposited on the first sacrificial layer 250 by a conventional semiconductor process such as Low Pressure Chemical Vapor Deposition (LPCVD), and then patterned by photolithography and etching to form a first structural layer 260. The first structural layer 260 covers the first sacrificial layer 250 and exposes the fourth protrusion 252 and the fourth protrusion 253, the first structural layer 260 positioned inside the fourth protrusion 252 and the fourth protrusion 253 forms a first partial first structural layer 261, the first structural layer 260 positioned outside the fourth protrusion 252 and the fourth protrusion 253 forms a second partial first structural layer 262, the first partial first structural layer 261 covering the third protrusion 251 forms a first step 263 at a first end of the first partial first structural layer 261, a second step 264 is formed at a second end of the first partial first structural layer 261, and a torsion swing arm 261, a first brake spring 263 and a second brake spring 264 are formed in a subsequent process. The material of the first structure layer 260 includes: the thickness of the polysilicon is 0.5 to 5 um, and the resistivity is less than 30 omega cm. Preferably, the first structural layer 260 has a thickness of 0.75 to 2 um and a resistivity of less than 10 Ω · cm.

It is to be understood that the embodiment of the present invention may also be implemented by depositing a seed layer of the first structural layer material on the first sacrificial layer 250 by a conventional semiconductor process method such as Low Pressure Chemical Vapor Deposition (LPCVD), epitaxially growing the first structural layer material, and then patterning the first structural layer material by photolithography and etching to form the first structural layer 260.

As shown in fig. 5f, a layer of a second sacrificial material is deposited on the first structure layer 260 by a conventional semiconductor process such as thermal oxidation or Low Pressure Chemical Vapor Deposition (LPCVD) or Plasma Enhanced Chemical Vapor Deposition (PECVD), the second sacrificial material is planarized by a Chemical Mechanical Polishing (CMP) process, and then patterned by photolithography and etching to form a second sacrificial layer 270. The second sacrificial layer 270 covers the second portion of the first structure layer 262, the fourth protrusion 252, the fourth protrusion 253, and a portion of the first structure layer 261, and the second sacrificial layer 270 on the first portion of the first structure layer 261 includes: the first opening 271 and the second opening 272, and the first opening 271 and the second opening 272 expose a first portion of the first structural layer 261. Specifically, the first opening 271 includes: a plurality of sub-openings 273. In the first and

second openings

271, 272, first and second movable torsion pendulum blocks 281, 282 are subsequently formed. The material of the second sacrificial layer 270 includes: silicon dioxide, 0.5 to 2 um thick. Preferably, the thickness of the second sacrificial layer 270 is 0.75 to 1.5 um. Alternative materials for the second sacrificial layer 270 also include: SiO prepared from tetraethyl orthosilicate (TEOS)₂Low temperature chemical vapor deposition of SiO₂(LTO)。

As shown in fig. 5g, a layer of second structural layer material is deposited on the second sacrificial layer 270 by a conventional semiconductor process such as Low Pressure Chemical Vapor Deposition (LPCVD), the second structural layer material is planarized by a Chemical Mechanical Polishing (CMP) process, and then patterned by a conventional process such as BOSCH etching process to form a second structural layer 280. The second structural layer 280 covering the first and

second openings

271, 272 forms a first movable torsion pendulum block 281 and a second movable torsion pendulum block 282, respectively. Specifically, the second structural layer 280 covering the plurality of sub openings 273 forms a plurality of sub movable torsion pendulum blocks 283. The second structural layer 280 located inside the first and

second openings

271 and 272 forms a torsion pendulum 284, a first fixed electrode 285, and a second fixed electrode 286. The second structural layer 280 located outside the first and

second openings

271, 272 forms a protective wall 287. The first fixed electrode 285 and the second fixed electrode 286 are located at both sides of the torsion pendulum 284. A third opening 288 is included between the first fixed electrode 285 and the torsion pendulum 284, and a third opening 288 is included between the second fixed electrode 286 and the torsion pendulum 284. A fourth opening 289 is included between the first fixed electrode 285 and the second movable torsion pendulum block 282, and a fourth opening 289 is included between the second fixed electrode 286 and the first movable torsion pendulum block 281. Fifth opening 2810 is included between protection wall 287 and first movable torsion pendulum block 281 and fifth opening 2810 is included between protection wall 287 and second movable torsion pendulum block 282. The first movable torsion pendulum block 281 and the second movable torsion pendulum block 282 have different masses. The material of the second structural layer 280 includes: the thickness of the polycrystalline silicon is 10-50 um, and the resistivity is less than 30 omega cm. Preferably, second structural layer 280 has a thickness of 15 to 25 um and a resistivity of less than 10 Ω · cm.

In some embodiments, the second structural layer 280 may also be formed by the following manufacturing method: a seed layer of the second structure layer material is deposited on the second sacrificial layer 270 by conventional semiconductor processing methods such as Low Pressure Chemical Vapor Deposition (LPCVD). The material of the seed layer comprises: the thickness of the seed layer of the polysilicon is 0.2 to 0.6 um. Preferably, the seed layer has a thickness of 0.2 to 0.5 um. Then, a second structural layer material is epitaxially grown, planarized by a Chemical Mechanical Polishing (CMP) process, and patterned by a conventional process such as a BOSCH etching process to form a second structural layer 280.

As shown in fig. 5h, a cavity 291 is formed by etching the first sacrificial layer 250 and the second sacrificial layer 270 inside the fourth protrusion 252 and the fourth protrusion 253 through the third opening 288, the fourth opening 289, and the fifth opening 2810 by using a semiconductor conventional process technique such as selective wet etching HF acid or BOE solution or vapor phase etching. The first partial first structural layer 261 forms a torsion pendulum arm 261, the first step 263 forms a first detent spring 263, and the second step 264 forms a second detent spring 264. The first sacrificial layer 250, the second sacrificial layer 270, and a portion of the first structural layer 260 (the second partial first structural layer 262) located outside the fourth protrusion 252 and the fourth protrusion 253 form a support wall 290. The first braking structure (the first braking spring 263 and the second braking spring 264) of the torsion swing arm 261 is located below the protection wall 287. The distance between the inner side wall of the protection wall 287 and the first movable torsion pendulum block 281 is larger than the distance between the first brake spring 263 and the inner side wall of the support wall 290. The distance between the inner wall of the protection wall 287 and the second movable torsion pendulum block 282 is larger than the distance between the second brake spring 264 and the inner wall of the support wall 290. First movable torsion pendulum block 281, second movable torsion pendulum block 282, and torsion pendulum arm 261 form a movable structure of mems 200. The movable structure, the torsion pendulum 284, the first detection electrode 243, the second detection electrode 244, the first wiring electrode 241, the second wiring electrode 242, the first fixed electrode 285, and the second fixed electrode 286 are located in the cavity 291. The movable structure is limited in its range of motion within the cavity, and protective walls 287 and support walls 290 isolate the movable structure from the environment and act as a protective device.

The plurality of second bumps, the corresponding plurality of first bumps, and the plurality of first wiring electrodes form a plurality of bump structures, and the plurality of bump structures form a plurality of second stopper structures. The second braking structure is located below the torsional pendulum arm, and when the movable structure moves downwards, the second braking structure blocks the torsional pendulum arm from continuing to move downwards, so that the second braking structure limits the downward movement range of the movable structure. The first braking structure of the twisting swing arm is located below the protective wall, when the movable structure moves upwards, the first braking structure blocks the twisting swing arm to continue moving upwards, and the first braking structure limits the upward movement range of the movable structure. The distance between the inner side wall of the protection wall and the movable torsion and swing block is larger than the distance between the first braking structure and the inner side wall of the support wall, when the movable structure moves leftwards or rightwards, the first braking structure firstly touches the inner side wall of the support wall to prevent the movable torsion and swing block from touching the inner side wall of the protection wall, and the first braking structure limits the leftward or rightward moving range of the movable structure. The first braking structure and the second braking structure are used as mechanical stops, so that the transverse movement and the longitudinal movement of the movable structure are limited within a certain range, the problem that the movable structure is damaged under certain mechanical impact is solved, and the reliability of the micro-electromechanical sensor is improved.

In accordance with the embodiments of the present invention as set forth above, these embodiments are not exhaustive and do not limit the invention to the precise embodiments described. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and its practical application, to thereby enable others skilled in the art to best utilize the invention and its various embodiments with various modifications as are suited to the particular use contemplated. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A microelectromechanical sensor, comprising:

a substrate;

a plurality of fixed electrodes located above the torsion pendulum arm;

2. The microelectromechanical sensor of claim 1, characterized in that the torsional pendulum arm comprises: a first braking structure that provides braking in a left-right direction for the movable structure.

3. The microelectromechanical sensor of claim 1, characterized in that the torsional pendulum arm comprises: a first braking structure that provides braking in an upward direction for the movable structure.

4. The microelectromechanical sensor of claim 1, characterized in that the torsional pendulum arm comprises: a first braking structure that provides braking in a left-right direction and an upward direction for the movable structure.

5. The microelectromechanical sensor of claim 1, further comprising:

6. The microelectromechanical sensor of claim 1, characterized in that the torsional pendulum arm comprises: a first braking structure, the micro-electromechanical sensor further comprising: a second braking structure located on the substrate,

7. The microelectromechanical sensor of any of claims 2, 3, 4, and 6, characterized in that the first braking structure comprises: the first brake spring is positioned at the first end of the torsion swing arm, and the second brake spring is positioned at the second end of the torsion swing arm.

8. The microelectromechanical sensor of claim 5 or 6, characterized in that the buried layer further comprises: a plurality of first bumps, the plurality of wiring electrodes covering the plurality of first bumps, respectively.

9. The mems of claim 8, further comprising: a plurality of second protrusions on the substrate, the plurality of first protrusions covering the plurality of second protrusions, respectively.

10. The microelectromechanical sensor of claim 9, characterized in that the second brake structure comprises: a plurality of bump structures including the plurality of second bumps, the plurality of first bumps corresponding to the plurality of second bumps, and the plurality of wiring electrodes.

11. The microelectromechanical sensor of claim 1, further comprising: a plurality of second raised areas on the substrate, the plurality of first raised areas respectively overlying the plurality of second raised areas.

12. The microelectromechanical sensor of claim 1, characterized in that the plurality of detection electrodes comprises: a first detection electrode and a second detection electrode, the plurality of fixed electrodes including: a first fixed electrode and a second fixed electrode positioned at both sides of the torsion pendulum,

13. The microelectromechanical sensor of claim 1, characterized in that the plurality of movable torsion pendulum masses comprises: the first movable torsion pendulum block and the second movable torsion pendulum block are positioned on two sides of the torsion pendulum, and the mass of the first movable torsion pendulum block and the mass of the second movable torsion pendulum block are different.

14. The microelectromechanical sensor of claim 13, characterized in that the first movable torsion mass comprises a plurality of sub-movable torsion masses.

15. The microelectromechanical sensor of any of claims 2, 3, 4, and 6, characterized in that the first detent structure of the torsional pendulum arm is located below the protective wall.

16. The microelectromechanical sensor of any of claims 2, 3, 4, and 6, characterized in that an inner sidewall of the protective wall is a greater distance from the plurality of movable torsion blocks than the first detent structure is from an inner sidewall of the support wall.

17. The microelectromechanical sensor of claim 1, characterized in that the support wall comprises: a first sacrificial layer, a second sacrificial layer, and a portion of the first structural layer.

18. The microelectromechanical sensor of claim 17, characterized in that the first sacrificial layer has a thickness of 0.5 um to 2 um.

19. The microelectromechanical sensor of claim 17, characterized in that the thickness of the second sacrificial layer is 0.5 um to 2 um.

20. The microelectromechanical sensor of claim 1, characterized in that the microelectromechanical sensor comprises: a torsional pendulum accelerometer.