A MEMS inertial device and its manufacturing method

Abstract

The present invention belongs to the field of micro-electromechanical systems technology, and specifically provides a MEMS inertial device, comprising a circuit layer, a device layer, and a cap layer stacked and bonded in sequence; a circuit area is formed between the circuit layer and the cap layer; the cap layer is provided with a plurality of first grooves; a getter layer is deposited at the bottom of each of the plurality of first grooves; and the plurality of first grooves are connected to the circuit area. The MEMS inertial device provided by the present invention transfers the position of the getter from the circuit layer to the cap layer, and the volume of the cavity in the cap layer can be controlled by the cavity depth without increasing the cavity area, thereby making the size of the MEMS gyroscope smaller and providing more circuit design space for the circuit layer. It can also reduce the impact of parasitic capacitance, providing a new method for the manufacture of MEMS gyroscopes.

Description

Technical Field

[0001] The present invention belongs to the technical field of micro-electromechanical systems, and in particular relates to a MEMS inertial device and a manufacturing method thereof. Background Art

[0002] Microelectromechanical systems (MEMS) devices, such as gyroscopes, require operation in a vacuum or low-pressure environment to reduce gas resistance, improve sensitivity, and extend service life. During the use of MEMS devices, residual and released gases may affect device performance and reliability. Furthermore, the presence of gas molecules can cause corrosion and wear of MEMS devices. Getters capture residual gas molecules through chemical adsorption and surface diffusion, preventing them from evaporating or migrating. This allows MEMS devices, such as gyroscopes, to operate stably in high vacuum environments, maintaining a stable internal environment and improving performance and reliability.

[0003] Therefore, getters are essential in MEMS gyroscope manufacturing. In existing MEMS gyroscope manufacturing methods, getters are typically placed on the circuit surface or in a separate area. When placed on the circuit surface, the resulting parasitic capacitance can have a significant impact on MEMS gyroscope performance. When placed separately, getters occupy a significant area, increasing the size of the MEMS gyroscope. Summary of the Invention

[0004] The purpose of the present invention is to overcome the problem in the prior art that getter generates parasitic capacitance that affects the performance of a MEMS gyroscope or increases the size of the MEMS gyroscope.

[0005] To this end, the present invention provides a MEMS inertial device, comprising a circuit layer, a device layer and a cap layer stacked and bonded in sequence; a circuit area is formed between the circuit layer and the cap layer; the cap layer is provided with a plurality of first grooves; a getter layer is deposited at the bottom of each of the plurality of first grooves; and the plurality of first grooves are connected to the circuit area.

[0006] Specifically, a plurality of second grooves are provided on the surface where the circuit layer is bonded to the device layer; first electrodes are provided in the second grooves; and the circuit layer is bonded to the device layer via the plurality of first electrodes.

[0007] Specifically, the device layer is provided with a plurality of support beams bonded one-to-one with the first electrodes.

[0008] Specifically, a plurality of first channels penetrating the device layer are opened on the device layer; and a plurality of the first grooves are connected to the circuit area through the corresponding first channels.

[0009] Specifically, the support beam includes a support beam body; one end of the support beam body is connected to the device layer, and the other end is provided with a second electrode; the second electrode is bonded to the first electrode.

[0010] The present invention also provides a method for manufacturing the above-mentioned MEMS inertial device, comprising the following steps:

[0011] S1, manufacturing circuit layer;

[0012] S2, manufacturing device layer;

[0013] S3, manufacturing a capping layer: performing patterning on one surface of the capping layer to form first grooves; depositing a getter at the bottom of a plurality of the first grooves;

[0014] S4. Bonding: Bonding the circuit layer to the device layer; performing comb-tooth patterning on the device layer to form a plurality of first channels penetrating the device layer; bonding the cap layer to the device layer to connect the first grooves to the corresponding first channels respectively.

[0015] Specifically, the above step S1 includes:

[0016] S101, providing a first substrate, depositing a first dielectric layer on a surface of the first substrate, and performing patterning on the first dielectric layer to expose a portion of the first substrate;

[0017] S102, depositing a first metal layer, and performing patterning on the first metal layer to expose a portion of the first dielectric layer;

[0018] S103, depositing a second dielectric layer, and patterning the second dielectric layer to expose a portion of the first metal layer;

[0019] S104, depositing a second metal layer to cover the first metal layer and the second dielectric layer, and patterning the second metal layer to form a first electrode;

[0020] S105 , depositing a third dielectric layer to cover the second dielectric layer and the first electrode, and performing patterning on the third dielectric layer to expose the first electrode.

[0021] Specifically, the above step S2 includes:

[0022] S201, providing a second substrate, depositing a third metal layer on a surface of the second substrate, and patterning the third metal layer to expose a portion of the second substrate;

[0023] S202 , performing patterning on the exposed second substrate, removing a portion of the second substrate, and forming a support beam.

[0024] Specifically, the above step S3 includes:

[0025] S301, providing a third substrate, depositing a fourth dielectric layer on the surface of the third substrate, and patterning the fourth dielectric layer and the third substrate to form a first groove;

[0026] S302 , depositing a getter at the bottom of the first groove.

[0027] Specifically, the above step S3 further includes: S303 , patterning the fourth dielectric layer and the third substrate to form a third groove.

[0028] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0029] 1. The MEMS inertial device provided by the present invention shifts the location of the getter from the circuit layer to the cap layer. The volume of the cap layer cavity can be controlled by the cavity depth without increasing the cavity area. This makes the MEMS gyroscope smaller, providing more space for circuit design in the circuit layer. It also reduces the impact of parasitic capacitance, providing a new method for MEMS gyroscope manufacturing.

[0030] 2. The MEMS inertial sensor provided by the present invention deposits a getter at the bottom of the first groove by providing a first groove in the cap layer. This eliminates the need to reserve space in the circuit layer or a separate area, reducing mask design, etching, and deposition steps, and lowering process complexity. The first groove structure is directly integrated into the cap layer wafer, and the getter is deposited within the groove, making it compatible with wafer-level packaging. This prevents bonding pressure from causing getter material to peel off and contaminate sensitive structures in the circuit layer. Furthermore, the first groove keeps the getter as far away from the circuit layer as possible, preventing the high temperature of bonding from suddenly damaging its structure and maintaining the getter's high specific surface area and gas absorption capacity. The first groove is designed in conjunction with the vertical first channel. By adjusting the gas evolution time and getter dosage, the cavity pressure can be stabilized within a certain range, allowing precise control of the cavity pressure to meet the vacuum requirements of different MEMS devices. Furthermore, by directing heating or applying an electric field to the bottom of the first groove on one side of the cap layer, the getter can be activated synchronously during the bonding process, eliminating the need for a separate high-temperature treatment step and optimizing activation conditions.

[0031] 3. The MEMS inertial sensor provided by the present invention uses a first electrode and a second electrode for bonding, and directly establishes electrical interconnection between the circuit layer and the device layer at the same time as the interface is combined, which reduces the difficulty of electrical interconnection. The bimetallic bonding interface has high mechanical strength and can effectively resist vibration and impact during the operation of the inertial sensor, reducing the risk of delamination. At the same time, the thermal expansion coefficient of the metal material is well matched, which can improve the stability of the device under temperature changes. The thermal conductive path formed by the metal electrode bonding helps to quickly conduct the heat generated by the MEMS device during operation to the packaging substrate, improving the stability and life of the sensor in high-temperature environments. The first electrode and the second electrode are preferably bonded with heterogeneous metals, and the material properties are complementary and optimized to achieve low-temperature bonding, avoiding damage to the MEMS microstructure caused by high temperature. It can also be targeted to meet the requirements of the circuit layer and the device layer, reducing transmission loss and signal interference, and improving the sensor signal-to-noise ratio. In addition, the metal bonding interface has excellent shear strength, and the failure rate is lower than that of wire bonding in a vibration environment, avoiding breakage or performance drift at the electrode connection, and enhancing reliability.

[0032] The present invention will be described in further detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 AB is a flowchart corresponding to step S101, C is a flowchart corresponding to step S102, DE is a flowchart corresponding to step S103, F is a flowchart corresponding to step S104, and GH is a flowchart corresponding to step S105.

[0034] Figure 2 AB is a flowchart corresponding to step S201, and C is a flowchart corresponding to step S202.

[0035] Figure 3 1 is a schematic diagram of manufacturing the capping layer in an embodiment of the present invention; wherein AC is a flow chart corresponding to step S301, D is a flow chart corresponding to step S302, and E is a flow chart corresponding to step S303.

[0036] Figure 4 Schematic diagram of bonding between the device layer and the circuit layer in an embodiment of the present invention; wherein A is a flowchart corresponding to step S401, B is a flowchart corresponding to step S402, and C is a flowchart corresponding to step S403.

[0037] Figure 5 Schematic diagram of bonding between the cap layer and the device layer in an embodiment of the present invention; wherein A is a flowchart corresponding to step S404, and B is a flowchart corresponding to step S405.

[0038] Figure 6Schematic diagram of the structure of a MEMS inertial device provided by an embodiment of the present invention.

[0039] Figure numerals: 1, circuit layer; 101, second groove; 102, first electrode; 2, device layer; 201, second electrode; 202, support beam body; 203, first channel; 3, cap layer; 301, first groove; 302, getter layer; 303, third groove. DETAILED DESCRIPTION

[0040] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Although the representative embodiments of the present invention have been described in detail, it will be understood by those skilled in the art that various modifications and changes can be made to the present invention without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the embodiments, but should be defined by the appended claims and their equivalents.

[0041] The present invention provides a MEMS inertial device, comprising a circuit layer, a device layer, and a cap layer stacked and bonded in sequence; a circuit area is formed between the circuit layer and the cap layer; a plurality of first grooves are provided on the side where the cap layer is bonded to the device layer, generally on the lower surface of the cap layer; a getter layer is deposited at the bottom of each of the plurality of first grooves; and the plurality of first grooves are connected to the circuit area. By transferring the position of the getter from the circuit layer to the cap layer, the volume of the cavity in the cap layer can be controlled by the cavity depth without increasing the cavity area, thereby making the MEMS gyroscope smaller and providing more circuit design space for the circuit layer. It can also reduce the impact of parasitic capacitance, providing a new method for manufacturing MEMS gyroscopes.

[0042] Specifically, the surface where the circuit layer and the device layer are bonded, generally the upper surface of the circuit layer, is provided with a plurality of second grooves; first electrodes are provided in the second grooves; the circuit layer is bonded to the device layer via the plurality of first electrodes. The second grooves cooperate with the device layer to protect the circuit structure.

[0043] In one embodiment, the surface where the device layer and circuit layer are bonded, typically the lower surface of the device layer, is provided with multiple support beams, each bonded to the first electrode. Providing support beams below the device layer effectively reduces deformation of the thin film structure and improves the machining accuracy and yield of the MEMS structure. The shape, size, location, and number of the support beams can be flexibly selected based on actual needs.

[0044] Preferably, the support beam includes a support beam body; one end of the support beam body is connected to the device layer, and the other end is provided with a second electrode; the second electrode is bonded to the first electrode. The materials of the first electrode and the second electrode can be selected as needed, and are generally Al or Ge.

[0045] Furthermore, the surface where the device layer and the cap layer are bonded, generally the upper surface of the device layer, is provided with a plurality of first channels penetrating the device layer; and the plurality of first grooves are connected to the circuit area through the corresponding first channels.

[0046] In one embodiment, a plurality of first grooves and a plurality of third grooves are provided on one side of the cap layer bonded to the device layer, and the first grooves and the third grooves are arranged at intervals. At this time, the number of first channels is equal to the sum of the number of first grooves and third grooves, ensuring that each first groove and third groove has a corresponding first channel connected to the circuit area.

[0047] The present invention also provides a method for manufacturing a MEMS inertial device, comprising the following steps:

[0048] S1. Manufacturing circuit layer

[0049] S101, providing a first substrate, and performing a patterning process on the substrate (refer to Figure 1 A portion of the first substrate is deposited on the first dielectric layer, the first dielectric layer is patterned to expose a portion of the first substrate (refer to Figure 1 Part B);

[0050] S102. Reference Figure 1 In part C, metal is deposited on the surface of the first dielectric layer to cover the first dielectric layer and the first substrate to form a first metal layer, and the first metal layer is patterned to expose a portion of the first dielectric layer;

[0051] S103, continue to deposit the second dielectric layer along the stacking direction and planarize it so that it covers the first dielectric layer and the first metal layer (refer to Figure 1 The second dielectric layer is patterned to expose part of the first metal layer (refer to Figure 1 (Part E);

[0052] S104. Reference Figure 1 In the middle F portion, metal is continuously deposited along the stacking direction to cover the first metal layer and the second dielectric layer to form a second metal layer. The second metal layer is patterned to expose a portion of the second dielectric layer to form a first electrode.

[0053] S105, continue to deposit the third dielectric layer along the stacking direction and planarize it, covering the second dielectric layer and the first electrode (refer to Figure 1The third dielectric layer is patterned to form a second groove and expose the first electrode in the second groove (refer to Figure 1 (see Section H in the figure).

[0054] S2. Manufacturing device layer

[0055] S201, providing a second substrate, and performing a patterning process on the second substrate (refer to Figure 2 A portion of the second substrate is formed by depositing metal on the surface of the second substrate to form a third metal layer, and the third metal layer is patterned to expose a portion of the second substrate and form a second electrode (refer to Figure 2 Part B);

[0056] S202, reference Figure 2 In the middle C portion, the exposed second substrate is patterned to remove a portion of the second substrate to form a support beam, thereby creating a space between the first support beam and the circuit layer during bonding. The first support beam preferably includes a first support beam body formed from a portion of the second substrate and a second electrode formed at one end of the first support beam body.

[0057] S3, manufacturing cap layer

[0058] S301, reference Figure 3 In the middle AC part, a third substrate is provided, a fourth dielectric layer is deposited on the surface of the third substrate, and the fourth dielectric layer and the third substrate are patterned to form a first groove;

[0059] S302, reference Figure 3 In the middle D part, a getter is deposited at the bottom of the first groove;

[0060] S303, reference Figure 3 In the middle E portion, the fourth dielectric layer and the third substrate are patterned to form a third groove.

[0061] S4. Bonding

[0062] S401, reference Figure 4 In the middle A part, the first electrode of the circuit layer is bonded to the second electrode of the device layer. Since the second substrate has been patterned, part of the thickness of the second substrate is removed to form the first support beam. During bonding, the second substrate and the third dielectric layer will not interfere with each other, thus protecting the electrodes.

[0063] S402, reference Figure 4 In part B, the second substrate of the device layer is thinned;

[0064] S403, reference Figure 4In the middle C part, the second substrate of the device layer is subjected to comb-tooth patterning to form a plurality of first channels penetrating the device layer, that is, the second substrate is structurally released to form a mass block as a suspended structure;

[0065] S404, reference Figure 5 In part A, one side of the fourth dielectric layer of the cap layer, that is, the lower surface of the cap layer, is bonded to the upper surface of the second substrate (mass block) of the device layer. The cap layer and the circuit layer are enclosed to form a circuit area, and the first groove and the third groove are connected to the circuit area through corresponding first channels respectively.

[0066] S405, reference Figure 5 In part B, the third substrate of the capping layer and the first substrate of the circuit layer are thinned.

[0067] The effects of the MEMS inertial device, its manufacturing method, and application of the present invention are studied below through specific embodiments.

[0068] Example 1: Reference Figure 6 This embodiment provides a MEMS inertial device, including: a circuit layer, a device layer and a cap layer.

[0069] Wherein, a plurality of second grooves are formed on the upper surface of the circuit layer; and first electrodes are provided in the second grooves.

[0070] The lower surface of the device layer is provided with multiple support beams corresponding to the first electrodes one by one; the support beams include a support beam body; one end of the support beam body is connected to the device layer, and the other end is provided with a second electrode; the device layer is provided with multiple first channels that pass through the device layer.

[0071] The lower surface of the cap layer is provided with a plurality of first grooves and a plurality of third grooves arranged at intervals; a getter layer is deposited at the bottom of the first grooves; and the sum of the number of the first grooves and the third grooves is equal to the number of the first channels.

[0072] The first electrode of the circuit layer is bonded to the second electrode of the device layer, the lower surface of the cap layer is bonded to the upper surface of the device layer, and a circuit area is formed between the circuit layer and the cap layer. The first groove and the third groove are respectively connected to the circuit area through corresponding first channels.

[0073] The MEMS inertial device provided in this embodiment shifts the location of the getter from the circuit layer to the cap layer. The volume of the cap layer cavity can be controlled by the cavity depth without increasing the cavity area, thereby making the MEMS gyroscope smaller, providing more space for circuit design in the circuit layer, and reducing the impact of parasitic capacitance.

[0074] Example 2: Reference Figure 1-5This embodiment provides a method for manufacturing a MEMS inertial device, which is characterized by comprising the following steps:

[0075] S1. Manufacturing circuit layer

[0076] S101: Provide a wafer as a substrate and perform alignment mark patterning on the wafer. Deposit SiO2 on the surface of the substrate to form a dielectric layer, and perform patterning to expose a portion of the substrate.

[0077] S102 , depositing metal Al on the surface of the dielectric layer to cover the dielectric layer and the substrate to form a metal layer, and performing patterning on the metal layer to expose a portion of the dielectric layer.

[0078] S103, continue to deposit SiO2 along the stacking direction and perform planarization processing to cover the upper dielectric layer and the metal layer, and then perform patterning processing to expose part of the metal layer.

[0079] S104 , continuing to deposit metal Al along the stacking direction to cover the metal layer and the SiO 2 dielectric layer, and performing patterning to expose a portion of the SiO 2 dielectric layer to form a first electrode.

[0080] S105 , continue depositing SiO 2 along the stacking direction to cover the metal layer and the dielectric layer, and perform planarization and patterning processing to form a second groove and expose the first electrode in the second groove.

[0081] S2. Manufacturing device layer

[0082] S201: Provide a silicon wafer as a substrate and perform alignment mark patterning on the wafer. Deposit metal Ge on the surface of the substrate to form a metal layer, pattern the metal layer, and expose a portion of the substrate to form a second electrode.

[0083] S202 , performing a patterning process on the exposed substrate, removing a portion of the thickness of the substrate, and forming a support beam; the support beam includes a support beam body formed by a portion of the substrate and a second electrode formed at one end of the support beam body.

[0084] S3, manufacturing cap layer

[0085] S301: Provide a silicon wafer as a substrate and perform alignment mark patterning on it. Deposit SiO2 on the substrate surface to form a dielectric layer and planarize it. Perform patterning on the dielectric layer and the substrate to form a plurality of first grooves.

[0086] S302 , depositing a getter and patterning it to form a getter layer at the bottom of the first groove.

[0087] S303: Patterning the dielectric layer and the substrate to form a plurality of third grooves (cavities); the first grooves and the third grooves are arranged at intervals. The volume of the cavities can be controlled by the cavity depth, without increasing the cavity area.

[0088] S4. Bonding

[0089] S401: Bond the first electrode (Al) of the circuit layer to the second electrode (Ge) of the device layer. Since the device layer substrate has been patterned, a portion of the substrate thickness is removed to form a support beam. This prevents interference between the substrate and the dielectric layer during bonding, protecting the electrodes.

[0090] S402 , thinning the substrate of the device layer.

[0091] S403 , performing comb-teeth patterning processing on the substrate of the device layer to form a plurality of first channels penetrating the substrate, and performing structural release on the substrate of the device layer to form a mass block as a suspended structure.

[0092] S404, bonding the dielectric layer (SiO2) of the cap layer to the upper surface (Si) of the substrate (mass block) of the device layer, so that the cap layer and the circuit layer enclose a circuit area, and the first groove and the third groove are connected to the circuit area through corresponding first channels respectively.

[0093] S405 , performing thinning processing on the substrate of the cap layer and the substrate of the circuit layer.

[0094] The above examples are merely illustrative of the present invention and do not limit the scope of protection of the present invention. Any design that is identical or similar to the present invention falls within the scope of protection of the present invention.

Claims

1. A MEMS inertial device, characterized in that: It includes a circuit layer, a device layer and a cap layer that are stacked and bonded in sequence; a circuit area is formed between the circuit layer and the cap layer; the cap layer is provided with a plurality of first grooves; a getter layer is deposited at the bottom of the plurality of first grooves; the plurality of first grooves are connected to the circuit area; the circuit layer is provided with a plurality of second grooves; a first electrode is provided in the second groove; the circuit layer is bonded to the device layer through the plurality of first electrodes; the device layer is provided with a plurality of support beams bonded one by one to the first electrodes; the support beam includes a support beam body; one end of the support beam body is connected to the device layer, and the other end is provided with a second electrode; the second electrode is bonded to the first electrode.

2. The MEMS inertial device according to claim 1, wherein: The device layer is provided with a plurality of first channels penetrating the device layer; and the plurality of first grooves are connected to the circuit area through the corresponding first channels.

3. The method for manufacturing a MEMS inertial device according to any one of claims 1 to 2, wherein: The following steps are involved: S1, manufacturing circuit layer; S2, manufacturing device layer; S3, manufacturing a capping layer: performing patterning on a surface of one side of the capping layer to form a plurality of first grooves; depositing a getter at the bottom of the plurality of first grooves; S4, bonding: bonding the circuit layer to the device layer; The device layer is subjected to comb-teeth patterning processing to form a plurality of first channels penetrating the device layer; the cap layer is bonded to the device layer to make the first grooves communicate with the corresponding first channels respectively.

4. The method for manufacturing a MEMS inertial device according to claim 3, wherein: The step S1 comprises: S101, providing a first substrate, depositing a first dielectric layer on a surface of the first substrate, and performing patterning on the first dielectric layer to expose a portion of the first substrate; S102, depositing a first metal layer, and performing patterning on the first metal layer to expose a portion of the first dielectric layer; S103, depositing a second dielectric layer, and patterning the second dielectric layer to expose a portion of the first metal layer; S104, depositing a second metal layer to cover the first metal layer and the second dielectric layer, and patterning the second metal layer to form a first electrode; S105 , depositing a third dielectric layer to cover the second dielectric layer and the first electrode, and performing patterning on the third dielectric layer to expose the first electrode.

5. The method for manufacturing a MEMS inertial device according to claim 3, wherein: The step S2 comprises: S201, providing a second substrate, depositing a third metal layer on a surface of the second substrate, and patterning the third metal layer to expose a portion of the second substrate; S202 , performing patterning on the exposed second substrate, removing a portion of the second substrate, and forming a support beam.

6. The method for manufacturing a MEMS inertial device according to claim 3, wherein: The step S3 comprises: S301, providing a third substrate, depositing a fourth dielectric layer on the surface of the third substrate, and patterning the fourth dielectric layer and the third substrate to form a first groove; S302 , depositing a getter at the bottom of the first groove.

7. The method for manufacturing a MEMS inertial device according to claim 6, wherein: The step S3 further includes: S303 , patterning the fourth dielectric layer and the third substrate to form a third groove.

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