MEMS accelerometer and manufacturing method

Abstract

The MEMS accelerometer comprises a body layer, a mass block is arranged in the middle of the body layer, electrode assemblies are arranged on the left side and the right side of the mass block respectively, and each electrode assembly comprises a transfer beam, a frame, a folding beam, a structural anchor point, a movable electrode, a fixed electrode and an electrode anchor point; the transfer beam is used for converting the up-down movement of the mass block into the left-right movement of the frame; a plurality of groups of electrode grooves are formed in the frame, the front side part and the rear side part in each electrode groove are respectively provided with a structural anchor point, and the structural anchor points are fixedly connected with a border of the frame through folding beams; framework beams are arranged between the electrode grooves in the frame, a plurality of movable electrodes are connected to the framework beams and extend into the electrode grooves, electrode anchor points are arranged in the middles of the electrode grooves, connecting arms are arranged on the front sides and the rear sides of the electrode anchor points respectively, and a plurality of fixed electrodes are arranged on the connecting arms. The fixed electrodes and the movable electrodes are arranged in a one-to-one correspondence mode to form detection capacitors. According to the invention, the linearity and the anti-blocking property of the MEMS accelerometer can be obviously improved.

Description

Technical Field

[0001] The present invention relates to the field of MEMS technology, and in particular to a MEMS accelerometer and a manufacturing method thereof. Background Art

[0002] A MEMS (Micro-Electro-Mechanical System) accelerometer is a miniature acceleration sensor manufactured using micro-nanotechnology. It measures the acceleration of an object and converts it into an electrical signal. MEMS accelerometers are widely used in many fields, such as motion monitoring, navigation, attitude control, and vibration detection. In traditional Z-axis MEMS capacitive accelerometers, the movable structure is typically a seesaw structure with asymmetric mass, and the detection principle is variable-spacing capacitance detection. The disadvantages of this type of MEMS accelerometer are poor linearity and susceptibility to sticking over a wide range. Summary of the Invention

[0003] The first object of the present invention is to provide a MEMS accelerometer in response to the problems existing in the existing MEMS accelerometers described in the background art.

[0004] To achieve the above objectives, the present invention is implemented through the following technical solutions: A MEMS accelerometer includes a body layer, a mass block in the middle of the body layer, and electrode assemblies on the left and right sides of the mass block, each electrode assembly including a conversion beam, a frame, a folding beam, a structural anchor point, a movable electrode, a fixed electrode, and an electrode anchor point; The conversion beam is used to convert the up-and-down motion of the mass block into the left-and-right motion of the frame. The middle of the conversion beam is fixedly connected to the mass block, and the two ends of the conversion beam are respectively fixedly connected to the two side frames of the frame. Several groups of electrode slots are provided in the frame, and structural anchor points are provided at the front and rear sides of each electrode slot, and the structural anchor points are fixedly connected to the frame frame through folding beams; There is a skeleton beam between the electrode slots in the frame, and multiple movable electrodes are connected to the skeleton beam. The movable electrodes extend into the electrode slots. An electrode anchor point is provided in the middle of the electrode slot, and connecting arms are provided on both sides of the electrode anchor point. Multiple fixed electrodes are provided on the connecting arms. The fixed electrodes and the movable electrodes are arranged in a one-to-one correspondence, and a detection capacitor is formed between the fixed electrodes and the movable electrodes.

[0005] In the above solution, the frame is a rectangular frame, which includes a left side frame, a right side frame, a front side frame and a rear side frame. A plurality of electrode slots are provided in the middle of the frame, and the separation beams between the electrode slots are skeleton beams.

[0006] In the above scheme, an even number of electrode slots are provided in the frame, and the structural anchor points, folded beams, electrode anchor points, fixed electrodes and movable electrodes in adjacent electrode slots are symmetrically arranged, so that the detection capacitors in adjacent electrode slots form differential capacitance. The number of electrode slots can be set as needed. For example, two electrode slots can be designed on the frame, and the part between the two electrode slots is a skeleton beam. The movable electrode is connected to the skeleton beam, and the fixed electrode is connected to the electrode anchor point. Because the structural anchor points, folded beams, electrode anchor points, fixed electrodes and movable electrodes in the two electrode slots are symmetrically arranged, when the frame moves, one group of the facing areas of the fixed electrodes and the movable electrodes in the two electrode slots must increase and the other group must decrease, thereby forming a differential capacitance. This design is conducive to eliminating the zero bias caused by common mode factors and improving sensor performance.

[0007] In the above scheme, connecting parts are respectively provided on the left and right sides of the mass block, the conversion beam is a long strip conversion beam, the middle part of the conversion beam is connected to the connecting part on the mass block, the front and rear frames of the frame are respectively provided with connecting ends extending toward the mass block, and the two ends of the conversion beam are respectively fixedly connected to the connecting ends at the ends of the front and rear frames of the frame.

[0008] In the above solution, the folding beam is a U-shaped beam, one end of the folding beam is fixedly connected to the structural anchor point, and the other end of the folding beam is fixedly connected to the front frame or the rear frame next to the structural anchor point.

[0009] In the above solution, the conversion beam is provided with a conversion portion for converting the vertical displacement of the mass block into the left-right displacement of the frame. The specific structure of the conversion beam can be designed as needed. For example, a stepped surface can be provided on the conversion beam, with the width below the stepped surface being greater than the width above the stepped surface.

[0010] In the above solution, motion suppressors are attached to the front and rear sides of the mass block. These motion suppressors comprise a motion suppression beam and a suppression structure anchor. The anchor is connected to the outer end of the motion suppression beam. The front and rear motion suppressors are located on the left and right sides of the mass block, respectively. By attaching these motion suppressors to the mass block, in-plane motion (e.g., left-right and front-back motion) is suppressed, while out-of-plane motion is minimally suppressed, virtually unaffected, and thus ensuring anti-stiction performance during acceleration detection.

[0011] In the above scheme, it also includes a substrate layer and a cap layer, the substrate layer is arranged at the bottom of the main body layer, and the cap layer is arranged at the top of the main body layer, the substrate layer includes a semiconductor substrate, an insulating layer and a conductor, the semiconductor substrate is arranged at the bottom of the substrate layer, the insulating layer is arranged on the semiconductor substrate, the conductor is arranged in the insulating layer and on the surface of the insulating layer, the conductor is conductively connected to the substrate layer, bonding areas are respectively provided on the left and right sides of the main body layer, a plurality of conductive connection columns are provided at the bottom of the main body layer, the conductive connection columns are respectively provided at positions corresponding to the bonding areas, electrode anchor points and structural anchor points on the main body layer, conductors are respectively provided at positions corresponding to the conductive connection columns on the upper surface of the insulating layer, the conductive connection columns are fixed and conductively connected to the conductors, cap columns are provided on the lower surface of the cap layer, the positions of the cap columns correspond to the positions of the bonding areas on the main body layer, and the cap columns are fixedly connected to the bonding areas.

[0012] A second object of the present invention is to provide a method for manufacturing a MEMS accelerometer, comprising the following steps: S1. Selecting a semiconductor sheet of a desired size for making a bulk layer; S2. Making a first mask on the upper side of the semiconductor sheet, and providing a through hole corresponding to the structure of the body layer on the first mask, wherein the through hole at the portion corresponding to the conversion beam corresponds to the shape of the upper portion of the conversion beam; S3. Making a second mask on the upper side of the first mask, and providing a through hole corresponding to the structure of the body layer on the second mask, wherein the through hole at the portion corresponding to the conversion beam corresponds to the shape of the lower portion of the conversion beam; S4, performing a first etching on the upper side of the semiconductor sheet, wherein the areas where the first mask and the second mask are located are protected, and the areas corresponding to the through holes are etched, and the etching depth is h1; S5. Remove the second mask, and then perform a second etching on the upper side of the semiconductor sheet. The area where the first mask is located is protected, and the area corresponding to the through hole is etched to a depth of h2. After the etching is completed, the desired body layer is obtained. Wherein, h2 corresponds to the height of the upper portion of the conversion beam, and h1+h2 is greater than or equal to the thickness of the body layer.

[0013] A third object of the present invention is to provide a method for manufacturing a MEMS accelerometer, comprising the following steps: S1. Selecting a semiconductor sheet of a desired size for making a bulk layer; S2. Making a third mask on the upper side of the semiconductor sheet, wherein the third mask is provided with a through hole corresponding to the shape of the upper portion of the conversion beam; S3, performing a first etching on the upper side of the body layer, wherein the area where the third mask is located is protected, and the area corresponding to the through hole is etched to a depth of h3, which corresponds to the height of the upper part of the conversion beam. After the etching is completed, the third mask is removed; S4. Making a fourth mask on the lower side of the semiconductor sheet, and providing a through hole on the fourth mask corresponding to the structure of the bulk layer, wherein the through hole at the portion corresponding to the conversion beam corresponds to the shape of the lower portion of the conversion beam; S5. Perform a second etching on the lower side of the body layer. The area where the fourth mask is located is protected, and the area corresponding to the through hole is etched. The etching depth is h4, and h3+h4 is greater than or equal to the thickness of the body layer. After the etching is completed, the desired body layer is obtained.

[0014] The present invention has positive effects: 1) The MEMS accelerometer of the present invention adopts a variable area capacitance change design. Compared with the variable spacing capacitance change design scheme in the prior art, it has better linearity in a large range, and the spacing between the fixed electrode and the movable electrode remains basically unchanged, thereby ensuring the anti-adhesion property of the MEMS accelerometer; 2) The MEMS accelerometer of the present invention converts the up and down displacement of the mass block into the left and right displacement of the frame through a conversion beam, drives the movable electrode to move relative to the fixed electrode, and changes the capacitance value by changing the relative area between the movable electrode and the fixed electrode, so as to detect the acceleration of the out-of-plane motion of the mass block. This design can greatly simplify the structure of the main body layer, making it easier to design and manufacture the main body layer; 3) In the MEMS accelerometer of the present invention, the electrode assemblies on both sides of the mass block are respectively designed with a conversion beam, a frame, a folding beam, a structural anchor point, a movable electrode, a fixed electrode and an electrode anchor point. This design can make the structure of the MEMS accelerometer more stable, not easy to be damaged, and extend its service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Schematic diagram of the structure of the body layer of the MEMS accelerometer of the present invention.

[0016] Figure 2 for Figure 1 AA section view in.

[0017] Figure 3 for Figure 1 BB section view in.

[0018] Figure 4 This is a schematic diagram of the structure in which a motion suppression component is provided on the main body layer.

[0019] Figure 5a Schematic diagram of the static state of the mass block in the main layer and the frames on the left and right sides.

[0020] Figure 5bThis is a schematic diagram showing the motion of the frames on the left and right sides when the mass block in the main body layer moves upward.

[0021] Figure 5c This is a schematic diagram showing the motion of the frames on the left and right sides when the mass block in the main body layer moves downward.

[0022] Figure 6a Schematic diagram of the simulation of the static state of the mass block in the main layer and the frames on the left and right sides.

[0023] Figure 6b This is a simulation diagram of the motion state of the frames on the left and right sides when the mass block in the main layer moves upward.

[0024] Figure 6c This is a simulation diagram of the motion state of the frames on the left and right sides when the mass block in the main layer moves downward.

[0025] Figure 7a Schematic diagram of the deformation state of the conversion beam when the mass block in the body layer moves upward.

[0026] Figure 7b Schematic diagram of the deformation state of the conversion beam when the mass block in the body layer moves downward.

[0027] Figure 8 FIG. 4 is a schematic diagram of a first method for manufacturing a MEMS accelerometer according to the present invention.

[0028] Figure 9 FIG. 4 is a schematic diagram of a second method for manufacturing a MEMS accelerometer according to the present invention.

[0029] Figure 10 Schematic diagram of the complete MEMS accelerometer structure.

[0030] Figure 11 Schematic diagram of the first connection method between the layers of a complete MEMS accelerometer.

[0031] Figure 12 Schematic diagram of the second connection method between the layers of a complete MEMS accelerometer.

[0032] Figure 13 Schematic diagram of the third connection method between the layers of a complete MEMS accelerometer.

[0033] Figure 14 Schematic diagram of the fourth connection method between the layers of a complete MEMS accelerometer.

[0034] The reference numerals in the figure are: main body layer 1, mass block 11, electrode assembly 12, conversion beam 121, frame 122, folding beam 123, structural anchor 124, movable electrode 125, electrode groove 126, skeleton beam 127, electrode anchor 13, connecting arm 14, fixed electrode 15, motion suppression member 16, motion suppression beam 161, suppression structure anchor 162, bonding area 17, conductive connecting column 18, substrate layer 2, semiconductor substrate 21, insulating layer 22, conductor 23, cap layer 3, cap column 31, first mask 4, second mask 5, third mask 6, fourth mask 7. DETAILED DESCRIPTION

[0035] The technical solutions of the present invention are described clearly and completely below through examples. It is obvious that the examples described are only some examples of the present invention, not all examples. All other examples derived by persons of ordinary skill in the art based on the examples of the present invention without creative effort are within the scope of protection of the present invention.

[0036] like Figure 1-7b As shown, the MEMS accelerometer of the present invention includes a body layer 1 , a mass block 11 is located in the middle of the body layer 1 , and electrode assemblies 12 are provided on the left and right sides of the mass block 11 .

[0037] The body layer 1 is made of semiconductor material, for example, single crystal silicon or polycrystalline silicon.

[0038] The mass block 11 may be a rectangular parallelepiped mass block, with connecting portions provided on the left and right sides of the mass block 11 , respectively. The connecting portions are protrusions protruding toward the two sides of the mass block 11 .

[0039] like Figure 4 As shown, to suppress in-plane displacement (e.g., left-right or front-back motion) of mass 11, motion suppressors 16 can be connected to the front and rear sides of mass 11. Motion suppressors 16 include motion suppressor beams 161 and suppressor structural anchors 162. Suppression structural anchors 162 are connected to the outer ends of motion suppressor beams 161. Front and rear motion suppressors 16 are located on the left and right sides of mass 11, respectively. Connecting motion suppressors 16 to mass 11 suppresses in-plane motion of mass 11, while having minimal effect on suppressing vertical motion. This has little impact on out-of-plane motion of the mass, thus ensuring the accelerometer's anti-stiction performance for acceleration detection.

[0040] As a preferred embodiment, the electrode assemblies 12 on both sides of the mass block 11 are symmetrically arranged.

[0041] Each electrode assembly 12 includes a conversion beam 121 , a frame 122 , a folding beam 123 , a structural anchor 124 , a movable electrode 125 , a fixed electrode 15 and an electrode anchor 13 .

[0042] The transfer beam 121 is an elongated strip, with its middle portion connected to a connection portion on the mass block 11. The transfer beam 121 is designed to extend in the front-to-back direction, with its ends fixedly connected to the front and rear frames of the frame 122. The front and rear frames of the frame 122 each have a connection end extending toward the mass block 11, and the ends of the transfer beam 121 are fixedly connected to the connection ends of the front and rear frames of the frame 122, respectively.

[0043] The conversion beam 121 is provided with a conversion portion for converting the up-down displacement of the mass block 11 into the left-right displacement of the frame 122. The specific structure of the conversion beam 121 can be designed as needed, for example, Figure 2 In the solution shown, a step surface is provided on the conversion beam 121 , and the width below the step surface is greater than the width above the step surface.

[0044] The frame 122 may be a rectangular frame, and includes a left side frame, a right side frame, a front side frame, and a rear side frame. A plurality of electrode slots 126 are provided in the middle of the frame 122 , and the separation beams between the electrode slots 126 are skeleton beams 127 .

[0045] The number of electrode slots 126 can be set as needed. For example, two electrode slots 126 can be designed on the frame 122 .

[0046] Structural anchor points 124 are respectively provided at the front and rear sides of each electrode slot 126 , and the structural anchor points 124 are fixedly connected to the border of the frame 122 via folding beams 123 .

[0047] The folding beam 123 can be a U-shaped beam, one side end of the folding beam 123 is fixedly connected to the structural anchor point 124 , and the other end of the folding beam 123 is fixedly connected to the front frame or the rear frame next to the structural anchor point 124 .

[0048] A plurality of movable electrodes 125 are connected to the skeleton beam 127, and the movable electrodes 125 extend into the electrode groove 126. An electrode anchor point 13 is provided in the middle of the electrode groove 126, and connecting arms 14 are provided on both sides of the electrode anchor point 13. A plurality of fixed electrodes 15 are provided on the connecting arms 14. The fixed electrodes 15 are arranged in a one-to-one correspondence with the movable electrodes 125, and a detection capacitor is formed between the fixed electrodes 15 and the movable electrodes 125.

[0049] An even number of electrode slots 126 are provided in the frame 122 , and the structural anchor points 124 , folded beams 123 , electrode anchor points 13 , fixed electrodes 15 and movable electrodes 125 in adjacent electrode slots 126 are symmetrically arranged so that the detection capacitors in adjacent electrode slots 126 form differential capacitors.

[0050] Taking the embodiment in which two electrode slots 126 are provided on the frame 122 as an example, the two electrode slots 126 are arranged in the left-right direction, and the separating beam between the two electrode slots 126 is a skeleton beam 127. Multiple movable electrodes 125 are connected to the skeleton beam 127, and the movable electrodes 125 extend into the electrode slots 126. The movable electrodes 125 are preferably arranged perpendicular to the skeleton beam 127. The fixed electrodes 15 are connected to the connecting arms on the front and rear sides of the electrode anchor 13. The fixed electrodes 15 are preferably arranged perpendicular to the connecting arms and are arranged one-to-one with each movable electrode 125. Preferably, the fixed electrodes 15 and the movable electrodes 125 are arranged parallel to each other. Because the structural anchor points 124, folded beams 123, electrode anchor points 13, fixed electrodes 15 and movable electrodes 125 in the two electrode slots 126 are symmetrically arranged, when the frame 122 moves, one group of the facing areas of the fixed electrodes 15 and the movable electrodes 125 in the two electrode slots 126 will inevitably increase and the other group will decrease, thereby forming a differential capacitance. This design is conducive to eliminating the zero bias caused by common mode factors and improving sensor performance.

[0051] like Figure 5a and 6a As shown, when the accelerometer has no acceleration, the mass block 11 and the frame 122 are at initial positions and have the same height.

[0052] like Figure 5b 、 6b As shown, when the acceleration is upward, the mass block 11 moves upward, driving the conversion beam 121 to deform. The conversion beam 121 converts the upward movement of the mass block 11 into a movement of the frame 122 away from the mass block 11.

[0053] like Figure 5c 、 6c As shown, when the acceleration is downward, the mass block 11 moves downward, driving the conversion beam 121 to deform. The conversion beam 121 converts the downward movement of the mass block 11 into the movement of the frame 122 toward the mass block 11.

[0054] There are four conversion beams 121 in total, two of which are connected to the left side of the mass block 11, one of which is connected to the front side and the other is connected to the rear side, and the other two are connected to the right side of the mass block 11, one of which is connected to the front side and the other is connected to the rear side. The conversion beams 121 on the left are symmetrically arranged with respect to the conversion beams 121 on the right.

[0055] like Figure 7a The transfer beam 121 shown is a schematic diagram of the structure of the transfer beam 121 connected to the left front side of the mass block 11. The α side of the transfer beam 121 is the end face where the transfer beam 121 connects to the frame 122, and the β side is the end face where the transfer beam 121 connects to the mass block 11. When the acceleration in the Z direction is zero, the α and β sides are at the same height, and the α side is located directly in front of the β side. When the acceleration is upward, the mass block 11 moves upward, causing the transfer beam 121 to twist and deform. The deformed α side is located diagonally below and to the left of the β side. The deformation of the transfer beam 121 located on the left rear side of the mass block 11 is symmetrical with the deformation of the aforementioned transfer beam 121 in the front-to-back direction. The α side twists to the left of the β side. As these two transfer beams 121 deform, they can drive the frame 122 on the left side of the mass block 11 to move leftward, away from the mass block 11. Similarly, the deformation of the two transfer beams 121 on the right side of the mass block 11 is symmetrical to the deformation of the two transfer beams 121 on the left side of the mass block 11 , thereby driving the frame 122 on the right side of the mass block 11 to move rightward and away from the mass block 11 .

[0056] like Figure 7b The transfer beam 121 shown is a schematic diagram of the structure of the transfer beam 121 connected to the left front side of the mass block 11. The α side of the transfer beam 121 is the end face where the transfer beam 121 connects to the frame 122, and the β side is the end face where the transfer beam 121 connects to the mass block 11. When the acceleration in the Z direction is zero, the α and β sides are at the same height, and the α side is directly in front of the β side. When the acceleration is downward, the mass block 11 moves downward, and the transfer beam 121 twists and deforms. The deformed α side is located diagonally above and to the right of the β side. The deformation of the transfer beam 121 located on the left rear side of the mass block 11 is symmetrical with the deformation of the aforementioned transfer beam 121 in the front-to-back direction. The α side twists to the right of the β side. As these two transfer beams 121 deform, they drive the frame 122 on the left side of the mass block 11 to the right, moving closer to the mass block 11. Similarly, the deformation of the two transfer beams 121 on the right side of the mass block 11 is symmetrical to the deformation of the two transfer beams 121 on the left side of the mass block 11 , thereby driving the frame 122 on the right side of the mass block 11 to move leftward and closer to the mass block 11 .

[0057] like Figure 8 As shown, the MEMS accelerometer of the present invention can be manufactured by two methods. The first manufacturing method includes the following steps: S1. Selecting a semiconductor sheet of a desired size for making a bulk layer; S2. A first mask 4 is formed on the upper side of the semiconductor sheet. Through holes corresponding to the structure of the body layer 1 are provided on the first mask 4. The through holes at the locations corresponding to the conversion beams 121 have a shape corresponding to the upper portion of the conversion beams 121. S3. A second mask 5 is formed on the upper side of the first mask 4. Through holes corresponding to the structure of the body layer 1 are provided on the second mask 5. The through holes at the locations corresponding to the conversion beams 121 correspond to the shape of the lower portions of the conversion beams 121. S4, performing a first etching on the upper side of the semiconductor sheet, the area where the first mask 4 and the second mask 5 are located is protected, and the area corresponding to the through hole is etched, and the etching depth is h1; S5, remove the second mask 5, and then perform a second etching on the upper side of the semiconductor sheet. The area where the first mask 4 is located is protected, and the area corresponding to the through hole is etched to a depth of h2. After the etching is completed, the desired body layer 1 is obtained; Wherein, h2 corresponds to the height of the upper portion of the conversion beam 121 , and h1 + h2 is greater than or equal to the thickness of the body layer 1 .

[0058] like Figure 9 As shown, the second manufacturing method of the MEMS accelerometer of the present invention includes the following steps: S1. Selecting a semiconductor sheet of a desired size for making a bulk layer; S2. Making a third mask 6 on the upper side of the semiconductor sheet, and providing a through hole on the third mask 6 corresponding to the shape of the upper portion of the conversion beam 121; S3, performing a first etching on the upper side of the body layer 1. The area where the third mask 6 is located is protected, and the area corresponding to the through hole is etched. The etching depth is h3, and the depth of h3 corresponds to the height of the upper part of the conversion beam. After the etching is completed, the third mask 6 is removed. S4. Form a fourth mask 7 on the lower side of the semiconductor sheet. Provide the fourth mask 7 with through holes corresponding to the structure of the body layer 1. The through holes at the locations corresponding to the conversion beams 121 have shapes corresponding to the lower portions of the conversion beams 121. S5. Perform a second etching on the lower side of the main layer 1. The area where the fourth mask 7 is located is protected, and the area corresponding to the through hole is etched. The etching depth is h4, and h3+h4 is greater than or equal to the thickness of the main layer 1. After the etching is completed, the required main layer 1 is obtained.

[0059] like Figure 10 As shown, when the MEMS accelerometer is made into a finished product, a substrate layer 2 and a cap layer 3 must also be designed. The substrate layer 2 is arranged at the bottom of the main body layer 1. The substrate layer 2 is used to lead out electrical signals and protect the main body layer 1. The cap layer 3 is arranged on the top of the main body layer 1. The cap layer 3 is used to protect the main body layer 1.

[0060] Substrate layer 2 includes a semiconductor substrate 21, an insulating layer 22, and conductors 23. Semiconductor substrate 21 is disposed at the bottom of substrate layer 2, and insulating layer 22 is disposed on the semiconductor substrate. Insulating layer 22 is used to isolate conductors with different potentials and is typically made of an insulating material such as silicon oxide. Conductors 23 are disposed within and on the surface of insulating layer 22 and are conductively connected to substrate layer 2. Bonding regions 17 are provided on the left and right sides of body layer 1, respectively. A plurality of conductive connection posts 18 are provided at the bottom of body layer 1. Conductive connection posts 18 are disposed at positions corresponding to bonding regions 17, electrode anchor points 13, and structural anchor points 124 on body layer 1. Conductors 23 are disposed on the upper surface of insulating layer 22 at positions corresponding to conductive connection posts 18. Conductive connection posts 18 are fixed to and conductively connected to conductors 23.

[0061] The bonding area 17 is arranged on the periphery of the movable structure of the body layer 1 to protect the internal structure of the body layer 1 .

[0062] The conductive connection posts 18 can be arranged in a variety of ways. In the first arrangement, the conductive connection posts 18 are integrally formed with the body layer 1. In the second arrangement, the conductive connection posts 18 are separately provided from the body layer 1 and then connected. In both arrangements, the conductive connection posts 18 serve two purposes: first, to provide a fixed conductive connection between the body layer 1 and the conductor 23; and second, to provide support for the body layer 1, thereby forming a cavity within the body layer 1 and enabling the movable portion of the body layer 1 to move up and down.

[0063] The insulating layer 22 is used to isolate conductors with different potentials and is usually made of insulating materials such as silicon oxide.

[0064] The conductor 23 is used to lead the electrical signal of the upper body layer 1 to a suitable location. The conductor 23 is usually made of a conductive material such as metal.

[0065] Capping columns 31 are provided on the lower surface of the capping layer 3 . The positions of the capping columns 31 correspond to the positions of the bonding areas 17 on the body layer 1 , and the capping columns 31 are fixedly connected to the bonding areas 17 , respectively.

[0066] The function of the cap layer 3 is to isolate the external environment, protect the main body layer 1 , and form a cavity above the main body layer 1 to facilitate the up and down movement of the movable part in the main body layer 1 .

[0067] A complete MEMS accelerometer is obtained by connecting multiple layers. In addition to the above-mentioned manufacturing method of the main body layer 1, it also includes a method of setting the substrate layer 2 and the cap layer 3. The different connection methods and connection orders between the layers are the reasons for the diversity of manufacturing methods.

[0068] like Figure 11-14As shown, according to the two conditions of whether the conductive connecting pillar 18 and the body layer 1 are integral, and whether the body layer 1 is first bonded to the cap layer 3, a complete MEMS accelerometer can be manufactured using four methods.

[0069] If the conductive connection pillar 18 and the body layer 1 are integral, the conductive connection pillar 18 can be manufactured by etching the body layer 1 or other methods.

[0070] The main body layer 1 can be connected to the substrate layer 2 first and then to the cap layer 3 , or the main body layer 1 can be connected to the cap layer 3 first and then to the substrate layer 2 .

[0071] If the conductive connection pillar 18 and the body layer 1 are not integral, the conductive connection pillar 18 can be manufactured on the substrate 2 by using deposition or other methods.

[0072] The main body layer 1 can be first connected to the substrate layer 2 and then connected to the cap layer 3; or the main body layer 1 can be first connected to the cap layer 3 and then connected to the substrate layer 2.

[0073] The main connection method between the above-mentioned main body layer 1 and the substrate layer 2 and the cap layer 3 is bonding and other methods. The bonding technology is divided into bonding with an intermediate layer and bonding without an intermediate layer. The present invention is not limited to a specific connection method. The emphasis is on connecting the multi-layer structure together to obtain a complete MEMS accelerometer.

[0074] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A MEMS accelerometer, characterized in that: It includes a body layer, the middle part of the body layer is a mass block, and electrode assemblies are respectively provided on the left and right sides of the mass block. Each set of electrode assemblies includes a conversion beam, a frame, a folding beam, a structural anchor point, a movable electrode, a fixed electrode and an electrode anchor point. The conversion beam is used to convert the up-and-down motion of the mass block into the left-and-right motion of the frame. The middle of the conversion beam is fixedly connected to the mass block, and the two ends of the conversion beam are respectively fixedly connected to the two side frames of the frame. Several groups of electrode slots are provided in the frame, and structural anchor points are provided at the front and rear sides of each electrode slot, and the structural anchor points are fixedly connected to the frame frame through folding beams; There is a skeleton beam between the electrode slots in the frame, and multiple movable electrodes are connected to the skeleton beam. The movable electrodes extend into the electrode slots. An electrode anchor point is provided in the middle of the electrode slot, and connecting arms are provided on both sides of the electrode anchor point. Multiple fixed electrodes are provided on the connecting arms. The fixed electrodes and the movable electrodes are arranged in a one-to-one correspondence, and a detection capacitor is formed between the fixed electrodes and the movable electrodes.

2. The MEMS accelerometer according to claim 1, wherein: The frame is a rectangular frame, comprising a left side frame, a right side frame, a front side frame and a rear side frame. A plurality of electrode slots are provided in the middle of the frame, and the separation beams between the electrode slots are skeleton beams.

3. The MEMS accelerometer according to claim 2, wherein: An even number of electrode slots are provided in the frame, and the structural anchor points, folding beams, electrode anchor points, fixed electrodes and movable electrodes in adjacent electrode slots are symmetrically arranged, so that the detection capacitors in adjacent electrode slots form differential capacitors.

4. The MEMS accelerometer according to claim 1, wherein: The left and right sides of the mass block are respectively provided with connecting parts, the conversion beam is a long strip conversion beam, the middle part of the conversion beam is connected to the connecting part on the mass block, the front and rear frames of the frame are respectively provided with connecting ends extending toward the mass block, and the two ends of the conversion beam are respectively fixedly connected to the connecting ends at the ends of the front and rear frames of the frame.

5. The MEMS accelerometer according to claim 1, wherein: The folding beam is a U-shaped beam, one end of the folding beam is fixedly connected to the structural anchor point, and the other end of the folding beam is fixedly connected to the front frame or the rear frame next to the structural anchor point.

6. The MEMS accelerometer according to claim 1, wherein: The conversion beam is provided with a conversion part for converting the up-and-down displacement of the mass block into the left-and-right displacement of the frame.

7. The MEMS accelerometer according to claim 1, wherein: The front and rear sides of the mass block are respectively connected to motion inhibitors, which include motion inhibitors that include a motion inhibitory beam and an inhibitory structure anchor point. The inhibitory structure anchor point is connected to the outer end of the motion inhibitory beam. The front motion inhibitor and the rear motion inhibitor are respectively arranged on the left and right sides of the mass block.

8. The MEMS accelerometer according to claim 1, wherein: It also includes a substrate layer and a cap layer, the substrate layer is arranged at the bottom of the main body layer, and the cap layer is arranged at the top of the main body layer, the substrate layer includes a semiconductor substrate, an insulating layer and a conductor, the semiconductor substrate is arranged at the bottom of the substrate layer, the insulating layer is arranged on the semiconductor substrate, the conductor is arranged in the insulating layer and on the surface of the insulating layer, the conductor is conductively connected to the substrate layer, bonding areas are respectively provided on the left and right sides of the main body layer, a plurality of conductive connection columns are provided at the bottom of the main body layer, the conductive connection columns are respectively provided at positions corresponding to the bonding areas, electrode anchor points and structural anchor points on the main body layer, conductors are respectively provided at positions corresponding to the conductive connection columns on the upper surface of the insulating layer, the conductive connection columns are fixed and conductively connected to the conductors, cap columns are provided on the lower surface of the cap layer, the positions of the cap columns correspond to the positions of the bonding areas on the main body layer, and the cap columns are fixedly connected to the bonding areas.

9. A method for manufacturing a MEMS accelerometer according to any one of claims 1 to 8, characterized in that: It includes the following steps: S1. Selecting a semiconductor sheet of a desired size for making a bulk layer; S2. Making a first mask on the upper side of the semiconductor sheet, and providing a through hole corresponding to the structure of the body layer on the first mask, wherein the through hole at the portion corresponding to the conversion beam corresponds to the shape of the upper portion of the conversion beam; S3. Making a second mask on the upper side of the first mask, and providing a through hole corresponding to the structure of the body layer on the second mask, wherein the through hole at the portion corresponding to the conversion beam corresponds to the shape of the lower portion of the conversion beam; S4, performing a first etching on the upper side of the semiconductor sheet, wherein the areas where the first mask and the second mask are located are protected, and the areas corresponding to the through holes are etched, and the etching depth is h1; S5. Remove the second mask, and then perform a second etching on the upper side of the semiconductor sheet. The area where the first mask is located is protected, and the area corresponding to the through hole is etched to a depth of h2. After the etching is completed, the desired body layer is obtained. Wherein, h2 corresponds to the height of the upper portion of the conversion beam, and h1+h2 is greater than or equal to the thickness of the body layer.

10. A method for manufacturing a MEMS accelerometer according to any one of claims 1 to 8, characterized in that: It includes the following steps: S1. Selecting a semiconductor sheet of a desired size for making a bulk layer; S2. Making a third mask on the upper side of the semiconductor sheet, wherein the third mask is provided with a through hole corresponding to the shape of the upper portion of the conversion beam; S3, performing a first etching on the upper side of the body layer, wherein the area where the third mask is located is protected, and the area corresponding to the through hole is etched to a depth of h3, which corresponds to the height of the upper part of the conversion beam. After the etching is completed, the third mask is removed; S4. Making a fourth mask on the lower side of the semiconductor sheet, and providing a through hole on the fourth mask corresponding to the structure of the bulk layer, wherein the through hole at the portion corresponding to the conversion beam corresponds to the shape of the lower portion of the conversion beam; S5. Perform a second etching on the lower side of the body layer. The area where the fourth mask is located is protected, and the area corresponding to the through hole is etched. The etching depth is h4, and h3+h4 is greater than or equal to the thickness of the body layer. After the etching is completed, the desired body layer is obtained.

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