Method for manufacturing a mems sensor and sensor
By setting a raised support structure and an insulating layer in the groove of the third wafer layer, the problem of insufficient structural strength in MEMS sensors is solved, the functional electrodes are effectively set, and the performance of the sensor is improved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SILEX MICROSYSTEMS (BEIJING) CO LTD
- Filing Date
- 2023-05-24
- Publication Date
- 2026-06-26
AI Technical Summary
In existing MEMS sensors, the structural strength between the third wafer layer and the second wafer layer is poor, and the space of the first wafer layer is limited, which cannot meet the requirements for setting up functional electrodes.
A raised support structure is set in the groove of the third wafer layer to increase the structural strength, and an insulating layer is formed between the third wafer layer and the second wafer layer. Functional electrodes are set in the space of the third wafer layer.
The structural strength between wafer layers was enhanced, and the requirements for setting functional electrodes were met, thereby improving the performance of the MEMS sensor.
Smart Images
Figure CN116605834B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of sensor technology, and in particular to a method for fabricating a MEMS sensor and the sensor itself. Background Technology
[0002] MEMS (micro electromechanical systems) sensors are miniature electromechanical systems characterized by high precision, high sensitivity, and low power consumption. They are widely used in mobile devices, smart homes, automobiles, medical devices, and industrial applications. Depending on the physical quantity measured and the application area, MEMS sensors can be categorized into gyroscopes, accelerometers, pressure sensors, temperature sensors, etc.
[0003] In related technologies, a MEMS sensor is provided, comprising a first wafer layer, a second wafer layer, and a third wafer layer bonded sequentially. The first wafer layer is a fixed electrode wafer layer, on which multiple functional electrodes are formed. The second wafer layer is a mass block wafer layer, including a mass block suspended from the first wafer layer by an anchor structure, and the mass block can vibrate within a groove around the anchor structure in a direction parallel or perpendicular to the second wafer layer. The third wafer layer is a capping wafer layer, with a groove on the side of the third wafer layer bonded to the second wafer layer to provide vibration space for the vibration of the mass block.
[0004] However, forming a groove on the side of the third wafer layer that is bonded to the second wafer layer results in poor structural strength between the third and second wafer layers. Furthermore, in the aforementioned MEMS sensor structure, all functional electrodes are located on the first wafer layer, but the limited space in the first wafer layer cannot meet the requirements of the MEMS sensor for the placement of functional electrodes. Summary of the Invention
[0005] In view of the above problems, this invention is proposed to provide a method for fabricating a MEMS sensor and a sensor that overcomes or at least partially solves the above problems. By setting a raised support structure in the groove of the third wafer layer, the structural strength between the second and third wafer layers can be strengthened. Simultaneously, by setting an insulating layer between the second and third wafer layers and forming a second functional electrode on the third wafer layer, the third wafer layer is fully utilized, further meeting the requirements of MEMS sensors for the placement of functional electrodes.
[0006] On the one hand, a method for fabricating a MEMS sensor is provided, the method comprising:
[0007] A first wafer layer is provided, and the first wafer layer has a plurality of first functional electrodes perpendicular to the first wafer layer, wherein the plurality of first functional electrodes are insulated from each other;
[0008] A second wafer layer is provided, the second wafer layer including at least one mass block;
[0009] A third wafer layer is provided, the third wafer layer having at least one second functional electrode perpendicular to the third wafer layer, and a first groove being provided on the surface of the third wafer layer for bonding with the second wafer layer;
[0010] At least one protruding support structure is formed within the first groove;
[0011] A second insulating layer is formed on the side of the third wafer layer that is used for bonding with the second wafer layer;
[0012] A third insulating layer is formed on the surface of the at least one protruding support structure for bonding with the second wafer layer;
[0013] The first wafer layer, the second wafer layer, and the third wafer layer are bonded sequentially, and each mass block is suspended on the first wafer layer by an anchor point structure, and the mass block can vibrate around the anchor point structure in a direction parallel or perpendicular to the second wafer layer.
[0014] Optionally, before sequentially bonding the first wafer layer, the second wafer layer, and the third wafer layer, the fabrication method further includes:
[0015] An isolation trench perpendicular to the first wafer layer is formed on the first wafer layer, dividing the first wafer layer into an inner wafer layer and an outer wafer layer that are mutually insulated and isolated from each other, wherein the plurality of first functional electrodes are located on the inner wafer layer;
[0016] A second conductive hole is formed on the second insulating layer, and a conductive material is formed within the second conductive hole.
[0017] Optionally, after sequentially bonding the first wafer layer, the second wafer layer, and the third wafer layer, the fabrication method further includes:
[0018] A first insulating layer is formed on the side of the first wafer layer that is away from the second wafer layer;
[0019] A plurality of first conductive holes are formed in the region of the first insulating layer corresponding to the inner wafer layer, and the plurality of first conductive holes correspond one-to-one with the plurality of first functional electrodes;
[0020] An electrode pad for electrical connection with the corresponding first functional electrode is formed within the plurality of first conductive holes.
[0021] Optionally, the preparation method further includes:
[0022] A third conductive hole is formed in the region of the first insulating layer corresponding to the outer wafer layer;
[0023] An electrode pad for electrical connection with the outer wafer layer is formed within the third conductive hole.
[0024] Optionally, the preparation method further includes:
[0025] A conductive layer is formed on the side of the third wafer layer away from the second wafer layer, and the conductive layer is electrically connected to the at least one second functional electrode.
[0026] Optionally, the preparation method further includes:
[0027] A second groove is formed on the side of the second wafer layer that is bonded to the first wafer layer.
[0028] In a second aspect, a MEMS sensor is provided, characterized in that the MEMS sensor is fabricated using the fabrication method described in the first aspect above, and the MEMS sensor includes a first wafer layer, a second wafer layer, and a third wafer layer bonded sequentially.
[0029] The first wafer layer has a plurality of first functional electrodes perpendicular to the first wafer layer, and the plurality of first functional electrodes are insulated from each other;
[0030] The second wafer layer includes at least one mass block, each of which is suspended from the first wafer layer by an anchor structure, and the mass block can vibrate about the anchor structure in a direction parallel or perpendicular to the second wafer layer.
[0031] The third wafer layer has a first groove on the side bonded to the second wafer layer, and the first groove has at least one protruding support structure. The third wafer layer has at least one second functional electrode perpendicular to the third wafer layer.
[0032] The MEMS sensor further includes a second insulating layer located between the third wafer layer and the second wafer layer, and a third insulating layer located between the protrusion support structure and the second wafer layer.
[0033] Optionally, the first wafer layer includes an inner wafer layer and an outer wafer layer located outside the inner wafer layer. An isolation trench perpendicular to the first wafer layer is provided between the inner wafer layer and the outer wafer layer. The inner wafer layer and the outer wafer layer are mutually insulated and isolated by the isolation trench. The plurality of first functional electrodes are located on the inner wafer layer.
[0034] The second insulation has a second conductive hole, and the second conductive hole contains a conductive material. The outer wafer layer and the second wafer layer are electrically connected to the at least one second functional electrode on the third wafer layer through the conductive material in the second conductive hole.
[0035] Optionally, the MEMS sensor further includes a first insulating layer located on the side of the first wafer layer away from the second wafer layer;
[0036] The first insulating layer has a plurality of first conductive holes that correspond one-to-one with the plurality of first functional electrodes, and the plurality of first conductive holes have electrode pads for electrical connection with the corresponding first functional electrodes.
[0037] Optionally, a third conductive hole corresponding to the outer wafer layer is formed on the first insulating layer, and an electrode pad for electrical connection with the outer wafer layer is provided in the third conductive hole.
[0038] The technical solutions provided in the embodiments of the present invention have at least the following technical effects or advantages:
[0039] This invention provides a method for fabricating a MEMS sensor and the sensor itself. At least one raised support structure is provided within a first groove of the third wafer layer. This raised support structure provides support and strengthens the structural strength between the third and second wafer layers. Simultaneously, electrical insulation between the third and second wafer layers is achieved by forming a second insulating layer between the third and second wafer layers and a third insulating layer between the raised support structure and the second wafer layer. At this point, at least one second functional electrode can be disposed on the third wafer layer using the space therein, further satisfying the functional electrode requirements of the MEMS sensor.
[0040] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description
[0041] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings.
[0042] In the attached diagram:
[0043] Figure 1This is a flowchart of a method for fabricating a MEMS sensor according to an embodiment of the present invention;
[0044] Figure 2 This is a cross-sectional view of a MEMS sensor provided in an embodiment of the present invention;
[0045] Figure 3 This is a partial structural schematic diagram of a MEMS sensor provided in an embodiment of the present invention. Detailed Implementation
[0046] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.
[0047] Figure 1 This is a flowchart of a method for fabricating a MEMS sensor according to an embodiment of the present invention, as shown below. Figure 1 As shown, the preparation method includes:
[0048] Step S101: Provide a first wafer layer, on which a plurality of first functional electrodes perpendicular to the first wafer layer are provided, and the plurality of first functional electrodes are insulated from each other.
[0049] The first wafer layer is a silicon wafer layer, specifically a highly doped single-crystal silicon layer. Adjacent first functional electrodes are separated by isolation vias perpendicular to the first wafer layer, and multiple first functional electrodes are mutually insulated through these isolation vias. All first functional electrodes are silicon electrodes, and the isolation vias can be formed using through-silicon via (TSV) technology.
[0050] Optionally, the multiple first functional electrodes may include a first frequency modulation electrode, a mass block electrode, a driving electrode, a driving detection electrode, a feedback electrode, and a detection electrode, etc.
[0051] Step S102: Provide a second wafer layer, the second wafer layer including at least one mass block.
[0052] The second wafer layer is a silicon wafer layer. Specifically, it can be a highly doped single-crystal silicon layer.
[0053] Step S103: Provide a third wafer layer, the third wafer layer having at least one second functional electrode perpendicular to the third wafer layer, and the surface of the third wafer layer for bonding with the second wafer layer having a first groove.
[0054] The third wafer layer is a silicon wafer layer. Specifically, it can be a highly doped single-crystal silicon layer. At least one second functional electrode is a silicon material electrode. In one implementation of this embodiment, at least one second functional electrode can be a second frequency-modulated electrode, and both the second and first frequency-modulated electrodes can be used to adjust the detection frequency of the MEMS sensor. In other implementations, at least one second functional electrode can also be a driving electrode, a driving detection electrode, a feedback electrode, or a detection electrode, etc., and this embodiment does not limit this. In the direction perpendicular to the second wafer layer, the height of at least one second functional electrode is less than the depth of the first groove.
[0055] In practice, the first groove can be etched on the third wafer layer.
[0056] Step S104: Form at least one raised support structure in the first groove.
[0057] Optionally, at least one of the protruding support structures is made of the same material as the third wafer layer, namely monocrystalline silicon.
[0058] In one implementation of this embodiment, at least one raised support structure may be formed between the anchor point structure of each mass block in the second wafer layer and the third wafer layer. In other implementations of this embodiment, at least one raised support structure may also be disposed between other areas of the second wafer layer (excluding each mass block) and the third wafer layer to prevent the mass blocks from contacting the raised support structure when vibrating.
[0059] Step S105: A second insulating layer is formed on the side of the third wafer layer that is used for bonding with the second wafer layer.
[0060] Step S106: Form a third insulating layer on one side of at least one raised support structure for bonding with the second wafer layer.
[0061] Step S107: Bond the first wafer layer, the second wafer layer and the third wafer layer in sequence, and suspend each mass block on the first wafer layer through the anchor point structure, and the mass block can vibrate around the anchor point structure in a direction parallel or perpendicular to the second wafer layer.
[0062] In a practical implementation, the first wafer layer, the second wafer layer, and the third wafer layer can be sequentially bonded using bonding layers. The bonding layers can be, for example, Au-Si layers or Si-SiO2 layers. Alternatively, the first wafer layer, the second wafer layer, and the third wafer layer can be bonded using direct Si-Si bonding. This embodiment does not limit this approach.
[0063] Optionally, before performing step S107, the preparation method may further include:
[0064] An isolation trench perpendicular to the first wafer layer is formed on the first wafer layer, dividing the first wafer layer into an inner wafer layer and an outer wafer layer that are mutually insulated and isolated. A plurality of first functional electrodes are located on the inner wafer layer. A second conductive hole is formed on the second insulating layer, and a conductive material is formed in the second conductive hole.
[0065] At this point, the outer wafer layer and the second wafer layer can be electrically connected to at least one second functional electrode on the third wafer layer through the conductive material within the second conductive via. By connecting the outer wafer layer to an external circuit, the connection between at least one second functional electrode and the external circuit can be achieved.
[0066] Optionally, after performing step S107, the preparation method may further include:
[0067] A first insulating layer is formed on the side of the first wafer layer away from the second wafer layer; a plurality of first conductive holes are formed in the region of the first insulating layer corresponding to the inner wafer layer, and the plurality of first conductive holes correspond one-to-one with a plurality of first functional electrodes; an electrode pad for electrical connection with the corresponding first functional electrode is formed in the plurality of first conductive holes.
[0068] At this time, multiple first functional electrodes can be electrically connected to external circuits with different voltages through corresponding electrode pads to achieve different functions.
[0069] Optionally, the preparation method may further include:
[0070] A third conductive hole is formed in the region of the first insulating layer corresponding to the outer wafer layer; an electrode pad for electrical connection with the outer wafer layer is formed in the third conductive hole.
[0071] At this point, since at least one second functional electrode is electrically connected to the outer wafer layer, at least one second functional electrode can be electrically connected to the external circuit through the electrode pad in the third conductive hole.
[0072] In this embodiment, the electrode pad 411 can be a metal electrode pad such as gold, silver, platinum, or aluminum, or other conductive alloy materials, etc. The present invention does not limit this.
[0073] Optionally, the preparation method further includes:
[0074] A conductive layer is formed on the side of the third wafer layer away from the second wafer layer, and the conductive layer is electrically connected to at least one second functional electrode. By forming the conductive layer to facilitate packaging, the second functional electrode can be electrically connected to an external circuit through the conductive layer.
[0075] Optionally, the preparation method further includes:
[0076] A second groove is formed on the surface of the second wafer layer that is used for bonding with the first wafer layer.
[0077] In practical implementation, a second groove can be etched into the second wafer layer. By setting the second groove, the vibration space of the mass block can be increased, allowing the mass block to vibrate in the second groove and the first groove in a direction parallel or perpendicular to the second wafer layer.
[0078] It should be noted that, in this embodiment, the above-described fabrication method can be used to fabricate a MEMS gyroscope. In other implementations, the above-described fabrication method can also be used to fabricate other MEMS sensors such as accelerometers, pressure gauges, resonators, and thermometers. This invention does not limit the scope of the invention in this regard.
[0079] This invention also provides a MEMS sensor, which is fabricated using the fabrication method described in the above embodiments. Figure 2 This is a cross-sectional view of a MEMS sensor provided in an embodiment of the present invention, as shown below. Figure 2 As shown, the MEMS sensor includes a first wafer layer 10, a second wafer layer 20, and a third wafer layer 30 bonded together in sequence.
[0080] The first wafer layer 10 has a plurality of first functional electrodes 11 perpendicular to the first wafer layer 10, and the plurality of first functional electrodes 11 are insulated from each other.
[0081] The second wafer layer 20 includes at least one mass block 21, each mass block 21 being suspended from the first wafer layer 10 by an anchor structure 22, and the mass block 21 being able to vibrate about the anchor structure 22 in a direction parallel or perpendicular to the second wafer layer 20.
[0082] The third wafer layer 30 has a first groove 30a on the side bonded to the second wafer layer 20, and at least one raised support structure 31 is provided in the first groove 30a. The third wafer layer 30 has at least one second functional electrode 32 perpendicular to the third wafer layer 30.
[0083] It should be noted that in this embodiment, the MEMS sensor is a MEMS gyroscope. In other implementations, the MEMS sensor can also be an accelerometer, pressure gauge, resonator, thermometer, or other sensor, and this invention does not limit it to these.
[0084] The MEMS sensor also includes a second insulating layer 42 located between the third wafer layer 30 and the second wafer layer 20, and a third insulating layer 43 located between the protrusion support structure 31 and the second wafer layer 20.
[0085] In this embodiment, the first wafer layer 10, the second wafer layer 20, and the third wafer layer 30 are all silicon wafer layers. Specifically, they can be highly doped single-crystal silicon layers. Adjacent first functional electrodes 11 are separated by isolation vias 10a perpendicular to the first wafer layer 10, and the multiple first functional electrodes 11 are mutually insulated and isolated through the isolation vias 10a. All first functional electrodes 11 are silicon material electrodes, and the isolation vias 10a can be insulating silicon vias. At least one second functional electrode 32 is located within the first groove 30a, and in the direction perpendicular to the second wafer layer 20, the height of at least one second functional electrode 32 is less than the depth of the first groove 30a.
[0086] For example, the difference between the height of at least one second functional electrode 32 and the depth of the first groove 30a is greater than a set value. The set value is the maximum vibration amplitude within the first groove 30a when the mass block 21 vibrates in a direction perpendicular to the second wafer layer 20, thereby ensuring that the second functional electrode 32 does not come into contact with the mass block 21 when the mass block 32 vibrates.
[0087] In one implementation of this embodiment, at least one raised support structure 31 is made of the same material as the third wafer layer 30, namely, monocrystalline silicon. The at least one raised support structure 31 can be disposed between the anchor point structure 22 of each mass block 21 of the second wafer layer 20 and the third wafer layer 30. In other implementations of this embodiment, the at least one raised support structure 31 can also be disposed between the other areas of the second wafer layer 20 (excluding the mass blocks 21) and the third wafer layer 30 to prevent the mass blocks 21 from contacting the raised support structure 31 during vibration.
[0088] Optionally, the first wafer layer 10 includes an inner wafer layer S1 and an outer wafer layer S2 located outside the inner wafer layer S1. An isolation trench 10b perpendicular to the first wafer layer 10 is provided between the inner wafer layer S1 and the outer wafer layer S2, and the inner wafer layer S1 and the outer wafer layer S2 are mutually insulated from each other through the isolation trench 10b. A plurality of first functional electrodes 11 are located on the inner wafer layer S1.
[0089] A second conductive hole 42a is formed on the second insulating layer 42, and the second conductive hole 42a contains conductive material. The outer wafer layer S2 and the second wafer layer 20 are electrically connected to at least one second functional electrode 32 on the third wafer layer 30 through the conductive material in the second conductive hole 42a.
[0090] Optionally, the MEMS sensor may also include a first insulating layer 41 located on the side of the first wafer layer 10 that is away from the second wafer layer 20.
[0091] The first insulating layer 41 has multiple first conductive holes 41a corresponding to the multiple first functional electrodes 11. Each of the multiple first conductive holes 41a has an electrode pad 411 for electrical connection with the corresponding first functional electrode 11. The multiple first functional electrodes 11 can be electrically connected to an external circuit through the corresponding electrode pad 411 to achieve different functions.
[0092] In this embodiment, the electrode pad 411 can be a metal electrode pad such as gold, silver, platinum, or aluminum, or other conductive alloy materials, etc. The present invention does not limit this.
[0093] Optionally, a third conductive hole 41b corresponding to the outer wafer layer S2 is provided on the first insulating layer 41, and an electrode pad 411 for electrical connection with the outer wafer layer S2 is provided in the third conductive hole 41b.
[0094] In the above implementation, at least one second functional electrode 32 and multiple first functional electrodes 31 can be electrically connected to external circuits with different voltages via electrode pad 411 to achieve different functions respectively.
[0095] In one implementation of this embodiment, the second wafer layer 20 and the third wafer layer 30 are bonded together by a bonding layer 50, which is a conductive layer. The conductive material within the second conductive via 42a can be the bonding layer 50, serving both conductive and bonding functions. Specifically, the bonding layer 50 can be an Au-Si layer or a Si-SiO2 layer.
[0096] In other implementations of this embodiment, the second wafer layer 20 and the first wafer layer 10 are also bonded together via a bonding layer 50. Alternatively, the first wafer layer, the second wafer layer 20, and the third wafer layer 30 can also be bonded together using Si-Si direct bonding. This embodiment does not limit this approach.
[0097] Optionally, a conductive layer 60 is provided on the side of the third wafer layer 30 away from the second wafer layer 20, which is electrically connected to at least one second functional electrode 22. By providing the conductive layer 60, the second functional electrode 22 can be electrically connected to an external circuit through the conductive layer 60 during packaging.
[0098] It should be noted that in this embodiment, at least one second functional electrode 32 can be electrically connected to the external circuit through the conductive layer 60 or through the electrode pad 411 in the third conductive hole 41b to realize the frequency modulation function.
[0099] Optionally, the second wafer layer 20 has a second groove 20a on the side bonded to the first wafer layer 10. The mass block 21 vibrates within the second groove 20a and the first groove 30a in a direction parallel or perpendicular to the second wafer layer 20 to ensure that the mass block has sufficient space to move.
[0100] In one implementation of this embodiment, a plurality of first functional electrodes 11 include a first frequency modulation electrode 11a, and at least one second functional electrode 32 includes a second frequency modulation electrode. The first frequency modulation electrode 11a and the second frequency modulation electrode are used to adjust the detection frequency of the MEMS sensor.
[0101] In other implementations of this embodiment, the plurality of first functional electrodes 11 further include a mass block electrode 11b, a driving electrode, a driving detection electrode, a feedback electrode, and a detection electrode (not shown in the figure). The second functional electrode 32 may also include other functional electrodes such as a driving electrode, a driving detection electrode, a feedback electrode, or a detection electrode.
[0102] Each of the aforementioned functional electrodes can be connected to an external circuit via a corresponding electrode pad. When the sensor is operating, a differential driving voltage is applied to the driving electrode by the external circuit to excite the driving mode of the MEMS sensor. The driving detection electrode can differentially detect the motion state of the driving mode and feed the detection result back to the driving electrode through the external circuit, thus achieving closed-loop driving. The detection electrode can differentially detect the motion state of the MEMS sensor in the detection mode and feed the detection result back to the feedback electrode through the external circuit, forming closed-loop detection.
[0103] Figure 3 This is a partial structural schematic diagram of a MEMS sensor provided in an embodiment of the present invention, as shown below. Figure 3 As shown, the second wafer layer 20 includes four mass blocks 21 symmetrically arranged along the center of the sensor, denoted as first mass block 21a, second mass block 21b, third mass block 21c, and fourth mass block 21d. Specifically, first mass block 21a and third mass block 21c are symmetrically arranged about the negative X-axis; second mass block 21b and fourth mass block 21d are symmetrically arranged about the positive X-axis; first mass block 21a and second mass block 21b are symmetrically arranged about the positive Y-axis; third mass block 21c and fourth mass block 21d are symmetrically arranged about the negative Y-axis; first mass block 21a and fourth mass block 21d are centrally symmetrically arranged; and third mass block 21c and second mass block 21b are centrally symmetrically arranged. The mass blocks are connected by coupling elastic beams.
[0104] A three-dimensional spatial coordinate system containing X-axis, Y-axis and Z-axis is established with the center point of the second wafer layer 20 as the origin. The X-axis and Y-axis are parallel to the end face of the second wafer layer 20, and the Z-axis is perpendicular to the end face of the second wafer layer 20.
[0105] In this embodiment, the third wafer layer 30 has a second frequency modulation electrode arranged corresponding to each mass block, and the first wafer layer 10 has a first frequency modulation electrode 11a, a mass block electrode, a driving electrode, a driving detection electrode, a feedback electrode, and a detection electrode (not shown in the figure) arranged corresponding to each mass block, so as to realize the driving, detection and other functions of each mass block respectively.
[0106] The technical solutions provided in the embodiments of the present invention have at least the following technical effects or advantages:
[0107] This invention provides a method for fabricating a MEMS sensor and the MEMS sensor itself. At least one raised support structure is provided within a first groove of the third wafer layer. This raised support structure provides support and strengthens the structural strength between the third and second wafer layers. Simultaneously, electrical insulation between the third and second wafer layers is achieved by forming a second insulating layer between the third and second wafer layers and a third insulating layer between the raised support structure and the second wafer layer. At this point, at least one second functional electrode can be disposed on the third wafer layer using the space therein, further satisfying the functional electrode requirements of the MEMS sensor.
[0108] Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.
[0109] Similarly, it should be understood that, in order to simplify this disclosure and aid in understanding one or more of the various aspects of the invention, in the above description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof. However, this method of disclosure should not be construed as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as reflected in the following claims, inventive aspects lie in fewer than all features of a single foregoing disclosed embodiment. Therefore, the claims following the detailed description are hereby expressly incorporated into this detailed description, wherein each claim itself is a separate embodiment of the invention.
[0110] It should be noted that the above embodiments are illustrative of the invention and not restrictive, and that those skilled in the art can devise alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses should not be construed as limiting the claims. The word "comprising" does not exclude the presence of components or steps not listed in the claims. The word "a" or "an" preceding a component does not exclude the presence of a plurality of such components. The invention can be implemented by means of hardware comprising several different components and by means of a suitably programmed computer. In the unit claims enumerating several means, several of these means may be embodied by the same item of hardware. The use of the words first, second, and third, etc., does not indicate any order. These words can be interpreted as names.
Claims
1. A method for fabricating a MEMS sensor, characterized in that, The preparation method includes: A first wafer layer is provided, and the first wafer layer has a plurality of first functional electrodes perpendicular to the first wafer layer, wherein the plurality of first functional electrodes are insulated from each other; A second wafer layer is provided, the second wafer layer including at least one mass block; A third wafer layer is provided, the third wafer layer having at least one second functional electrode perpendicular to the third wafer layer, and a first groove being provided on the surface of the third wafer layer for bonding with the second wafer layer; At least one protruding support structure is formed within the first groove; A second insulating layer is formed on the side of the third wafer layer that is bonded to the second wafer layer; a conductive layer is formed on the side of the third wafer layer that is away from the second wafer layer, and the conductive layer is electrically connected to the at least one second functional electrode. A third insulating layer is formed on the surface of the at least one protruding support structure for bonding with the second wafer layer; The first wafer layer, the second wafer layer, and the third wafer layer are bonded sequentially, and each mass block is suspended on the first wafer layer by an anchor point structure, and the mass block can vibrate around the anchor point structure in a direction parallel or perpendicular to the second wafer layer.
2. The preparation method according to claim 1, characterized in that, Before sequentially bonding the first wafer layer, the second wafer layer, and the third wafer layer, the fabrication method further includes: An isolation trench perpendicular to the first wafer layer is formed on the first wafer layer, dividing the first wafer layer into an inner wafer layer and an outer wafer layer that are mutually insulated and isolated from each other, wherein the plurality of first functional electrodes are located on the inner wafer layer; A second conductive hole is formed on the second insulating layer, and a conductive material is formed within the second conductive hole.
3. The preparation method according to claim 2, characterized in that, After sequentially bonding the first wafer layer, the second wafer layer, and the third wafer layer, the fabrication method further includes: A first insulating layer is formed on the side of the first wafer layer that is away from the second wafer layer; A plurality of first conductive holes are formed in the region of the first insulating layer corresponding to the inner wafer layer, and the plurality of first conductive holes correspond one-to-one with the plurality of first functional electrodes; An electrode pad for electrical connection with the corresponding first functional electrode is formed within the plurality of first conductive holes.
4. The preparation method according to claim 3, characterized in that, The preparation method further includes: A third conductive hole is formed in the region of the first insulating layer corresponding to the outer wafer layer; An electrode pad for electrical connection with the outer wafer layer is formed within the third conductive hole.
5. The preparation method according to claim 1, characterized in that, The preparation method further includes: A second groove is formed on the side of the second wafer layer that is bonded to the first wafer layer.
6. A MEMS sensor, characterized in that, The MEMS sensor is fabricated using the fabrication method described in any one of claims 1 to 5, and the MEMS sensor includes a first wafer layer, a second wafer layer, and a third wafer layer bonded sequentially. The first wafer layer has a plurality of first functional electrodes perpendicular to the first wafer layer, and the plurality of first functional electrodes are insulated from each other; The second wafer layer includes at least one mass block, each of which is suspended from the first wafer layer by an anchor structure, and the mass block can vibrate about the anchor structure in a direction parallel or perpendicular to the second wafer layer. The third wafer layer has a first groove on the side bonded to the second wafer layer, and the first groove has at least one protruding support structure. The third wafer layer has at least one second functional electrode perpendicular to the third wafer layer. The side of the third wafer layer away from the second wafer layer has a conductive layer, and the conductive layer is electrically connected to the at least one second functional electrode. The MEMS sensor further includes a second insulating layer located between the third wafer layer and the second wafer layer, and a third insulating layer located between the protrusion support structure and the second wafer layer.
7. The MEMS sensor according to claim 6, characterized in that, The first wafer layer includes an inner wafer layer and an outer wafer layer located outside the inner wafer layer. An isolation trench perpendicular to the first wafer layer is provided between the inner wafer layer and the outer wafer layer. The inner wafer layer and the outer wafer layer are mutually insulated and isolated by the isolation trench. The plurality of first functional electrodes are located on the inner wafer layer. The second insulation has a second conductive hole, and the second conductive hole contains a conductive material. The outer wafer layer and the second wafer layer are electrically connected to the at least one second functional electrode on the third wafer layer through the conductive material in the second conductive hole.
8. The MEMS sensor according to claim 7, characterized in that, The MEMS sensor further includes a first insulating layer located on the side of the first wafer layer away from the second wafer layer; The first insulating layer has a plurality of first conductive holes that correspond one-to-one with the plurality of first functional electrodes, and the plurality of first conductive holes have electrode pads for electrical connection with the corresponding first functional electrodes.
9. The MEMS sensor according to claim 8, characterized in that, A third conductive hole corresponding to the outer wafer layer is formed on the first insulating layer, and an electrode pad for electrical connection with the outer wafer layer is provided in the third conductive hole.