MEMS inertial device and manufacturing method thereof

Abstract

The invention belongs to the technical field of micro electro mechanical systems, and particularly provides an MEMS inertial device which comprises a circuit layer, a device layer and a cap layer which are sequentially stacked and bonded. A circuit area is defined between the circuit layer and the cap layer; the cap layer is provided with a plurality of first grooves; getter layers are deposited at the bottoms of the first grooves; and the plurality of first grooves are communicated with the circuit area. According to the MEMS inertial device provided by the invention, the position of the getter is transferred from the circuit layer to the cap layer, the volume of the cavity of the cap layer can be regulated and controlled through the depth of the cavity, and the area of the cavity does not need to be increased, so that the volume of the MEMS gyroscope is smaller, and more circuit design space is provided for the circuit layer. And the influence caused by parasitic capacitance can be reduced, and a new method is provided for manufacturing the MEMS gyroscope.

Description

Technical Field

[0001] The present invention belongs to the technical field of microelectromechanical systems, and particularly relates to a MEMS inertial device and a manufacturing method thereof. Background Art

[0002] Microelectromechanical system (MEMS) devices such as gyroscopes need to work in a vacuum or low-pressure environment to reduce gas resistance, improve sensitivity, and extend service life. During the use of MEMS devices, residual gases and released gases may affect the performance and reliability of the devices. In addition, the presence of gas molecules may cause corrosion and wear of MEMS devices. Getters capture residual gas molecules through chemical adsorption and surface diffusion, without evaporation or migration, enabling MEMS devices such as gyroscopes to work stably in a high-vacuum environment, maintaining the stability of the internal environment of the devices, and improving performance and reliability.

[0003] Therefore, getters are essential in the manufacturing of MEMS gyroscopes. In existing manufacturing methods of MEMS gyroscopes, getters are generally placed on the circuit surface or in a separate area. When the getter is placed on the circuit surface, the parasitic capacitance generated will more or less affect the performance of the MEMS gyroscope; when the getter is placed separately, it will occupy a certain area, thereby increasing the volume of the MEMS gyroscope. Summary of the Invention

[0004] The object of the present invention is to overcome the problem that the getter in the prior art generates parasitic capacitance, which affects the performance of the MEMS gyroscope or increases the volume of the MEMS gyroscope.

[0005] To this end, the present invention provides a MEMS inertial device, including a circuit layer, a device layer, and a capping layer that are sequentially stacked and bonded; a circuit area is formed by enclosing between the circuit layer and the capping layer; the capping layer is provided with a plurality of first grooves; getter layers are deposited at the bottoms of the plurality of first grooves; the plurality of first grooves communicate with the circuit area.

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

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

[0008] Specifically, a plurality of first channels penetrating the device layer are formed on the device layer; the plurality of first grooves communicate with the circuit area through the corresponding first channels.

[0009] Specifically, the above-mentioned 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 manufacturing method of the above-mentioned MEMS inertial device, including the following steps: S1. Manufacture a circuit layer; S2. Manufacture a device layer; S3. Manufacture a capping layer: perform patterning on one side surface of the capping layer to form a first groove; deposit a getter at the bottom of the plurality of first grooves; S4. Bonding: bond the circuit layer and the device layer; perform comb patterning on the device layer to form a plurality of first channels penetrating the device layer; bond the capping layer and the device layer so that the first grooves are respectively communicated with the corresponding first channels.

[0011] Specifically, the above-mentioned step S1 includes: S101. Provide a first substrate, deposit a first dielectric layer on the surface of the first substrate, and perform patterning on the first dielectric layer to expose part of the first substrate; S102. Deposit a first metal layer, and perform patterning on the first metal layer to expose part of the first dielectric layer; S103. Deposit a second dielectric layer, and perform patterning on the second dielectric layer to expose part of the first metal layer; S104. Deposit a second metal layer to cover the first metal layer and the second dielectric layer, and perform patterning on the second metal layer to form a first electrode; S105. Deposit a third dielectric layer to cover the second dielectric layer and the first electrode, and perform patterning on the third dielectric layer to expose the first electrode.

[0012] Specifically, the above-mentioned step S2 includes: S201. Provide a second substrate, deposit a third metal layer on the surface of the second substrate, and perform patterning on the third metal layer to expose part of the second substrate; S202. Perform patterning on the exposed second substrate to remove part of the thickness of the second substrate to form a support beam.

[0013] Specifically, the above-mentioned step S3 includes: S301. Provide a third substrate, deposit a fourth dielectric layer on the surface of the third substrate, and perform patterning on the fourth dielectric layer and the third substrate to form a first groove; S302. Deposit a getter at the bottom of the first groove.

[0014] Specifically, the above step S3 further includes: S303, patterning the fourth dielectric layer and the third substrate to form a third groove.

[0015] Compared with the prior art, the present invention has the following advantages and beneficial effects: 1. By transferring the position of the getter from the circuit layer to the capping layer in the MEMS inertial device provided by the present invention, the volume of the cavity in the capping layer can be regulated by the cavity depth without increasing the cavity area, thereby making the volume of the MEMS gyroscope smaller, providing more circuit design space for the circuit layer, and reducing the influence brought by parasitic capacitance, providing a new method for the manufacture of MEMS gyroscopes.

[0016] 2. By providing a first groove in the capping layer in the MEMS inertial sensor provided by the present invention, depositing the getter at the bottom of the first bottom, there is no need to reserve space in the circuit layer or a separate area, reducing the mask design, etching and deposition steps, and reducing the process complexity. The first groove structure is directly integrated into the capping layer wafer, and the getter is deposited in the groove, which is compatible with wafer-level packaging, avoiding the getter material peeling off due to bonding pressure and contaminating the sensitive structure of the circuit layer. Moreover, the first groove makes the getter as far away from the circuit layer as possible, avoiding the sudden destruction of its structure by the high temperature during bonding, and maintaining the high specific surface area and gas absorption capacity of the getter. The first groove is co-designed with the vertical first channel. By adjusting the gas evolution time and the amount of getter, the cavity pressure can be stabilized within a certain range, accurately controlling the cavity pressure to meet the vacuum requirements of different MEMS devices. In addition, the getter can be synchronously activated during the bonding process by directionally heating or applying an electric field to the bottom of the first groove on one side of the capping layer, without a separate high-temperature treatment step, optimizing the activation conditions.

[0017] 3. The MEMS inertial sensor provided by the present invention uses the first electrode and the second electrode for bonding, directly establishing electrical interconnection between the circuit layer and the device layer while achieving interface bonding, reducing the difficulty of electrical interconnection. The bimetallic bonding interface has high mechanical strength, can effectively resist vibration and impact during the operation of the inertial sensor, and reduces the risk of delamination. At the same time, the thermal expansion coefficient matching of the metal materials is good, which can improve the stability of the device under temperature changes. The heat conduction path formed by the bonding of the metal electrodes helps to quickly conduct the heat generated during the operation of the MEMS device to the packaging substrate, improving the stability and lifespan of the sensor in a high-temperature environment. The first electrode and the second electrode preferably use heterogeneous metal bonding, and the material characteristics are complementary and optimized, enabling low-temperature bonding, avoiding damage to the MEMS microstructure caused by high temperature. It can also be specifically adapted to the requirements of the circuit layer and the device layer, reducing transmission loss and signal interference, and improving the signal-to-noise ratio of the sensor. In addition, the metal bonding interface has excellent shear strength, and the failure rate under a vibration environment is lower than that of wire bonding, avoiding breakage or performance drift at the electrode connection, and enhancing the reliability.

[0018] The present invention will be further described in detail below in conjunction with the accompanying drawings. Description of the Drawings

[0019] Figure 1 It is a schematic diagram of the manufacturing of the circuit layer in an embodiment of the present invention; where A - B is the flowchart corresponding to step S101, C is the flowchart corresponding to step S102, D - E is the flowchart corresponding to step S103, F is the flowchart corresponding to step S104, and G - H is the flowchart corresponding to step S105.

[0020] Figure 2 It is a schematic diagram of the manufacturing of the device layer in an embodiment of the present invention; where A - B is the flowchart corresponding to step S201, and C is the flowchart corresponding to step S202.

[0021] Figure 3 It is a schematic diagram of the manufacturing of the capping layer in an embodiment of the present invention; where A - C is the flowchart corresponding to step S301, D is the flowchart corresponding to step S302, and E is the flowchart corresponding to step S303.

[0022] Figure 4 It is a schematic diagram of the bonding between the device layer and the circuit layer in an embodiment of the present invention; where A is the flowchart corresponding to step S401, B is the flowchart corresponding to step S402, and C is the flowchart corresponding to step S403.

[0023] Figure 5 It is a schematic diagram of the bonding between the capping layer and the device layer in an embodiment of the present invention; where A is the flowchart corresponding to step S404, and B is the flowchart corresponding to step S405.

[0024] Figure 6 It is a schematic diagram of the structure of the MEMS inertial device provided by an embodiment of the present invention.

[0025] Reference Numerals: 1, circuit layer; 101, second groove; 102, first electrode; 2, device layer; 201, second electrode; 202, support beam body; 203, first channel; 3, capping layer; 301, first groove; 302, getter layer; 303, third groove. Detailed Embodiments

[0026] The technical solutions in 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 of the embodiments. Although the representative embodiments of the present invention have been described in detail, those of ordinary skill in the technical field to which the present invention belongs will understand 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.

[0027] The present invention provides a MEMS inertial device, which includes a circuit layer, a device layer, and a capping layer that are stacked and bonded in sequence; a circuit region is formed by enclosing between the circuit layer and the capping layer; on the side of the capping layer bonded to the device layer, generally the lower surface of the capping layer, a plurality of first grooves are provided; getter layers are deposited on the bottoms of the plurality of first grooves; the plurality of first grooves communicate with the circuit region. By transferring the position of the getter from the circuit layer to the capping layer, the volume of the cavity in the capping layer can be regulated by the cavity depth, without the need to increase the cavity area, so that the volume of the MEMS gyroscope is smaller, providing more circuit design space for the circuit layer. Moreover, the influence brought by parasitic capacitance can be reduced, providing a new method for the manufacture of MEMS gyroscopes.

[0028] Specifically, on the surface of the circuit layer bonded to the device layer, generally the upper surface of the circuit layer, a plurality of second grooves are opened; first electrodes are provided in the second grooves; the circuit layer is bonded to the device layer through the plurality of first electrodes. By cooperating the second grooves with the device layer, the circuit structure is protected.

[0029] In one embodiment, on the surface of the device layer bonded to the circuit layer, generally the lower surface of the device layer, a plurality of support beams are provided that are bonded to the first electrodes one by one. By arranging the support beams below the device layer, the deformation of the thin film structure can be effectively reduced, and the processing accuracy and processing yield of the MEMS structure can be improved. The shape, size, position, and number of the support beams can be flexibly selected according to actual needs.

[0030] 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 according to needs, and generally Al or Ge is selected.

[0031] Further, on the surface of the device layer bonded to the capping layer, generally the upper surface of the device layer, a plurality of first channels penetrating the device layer are opened; the plurality of first grooves communicate with the circuit region through the corresponding first channels.

[0032] In one embodiment, a plurality of first grooves and a plurality of third grooves are opened on the side of the capping layer bonded to the device layer, and the first grooves and the third grooves are arranged at intervals. At this time, the number of the first channels is equal to the sum of the numbers of the first grooves and the third grooves, ensuring that each first groove and each third groove can have a corresponding first channel communicating with the circuit region.

[0033] The present invention also provides a manufacturing method of a MEMS inertial device, including the following steps: S1. Manufacture the circuit layer S101. Provide a first substrate and perform alignment marking patterning processing on it (refer to Figure 1Part A); Deposit a first dielectric layer on the surface of the first substrate, and pattern the first dielectric layer to expose a part of the first substrate (refer to Figure 1 Part B); S102. Refer to Figure 1 Part C, deposit a metal on the surface of the first dielectric layer to cover the first dielectric layer and the first substrate, form a first metal layer, and pattern the first metal layer to expose a part of the first dielectric layer; S103. Continuing to deposit a second dielectric layer along the stacking direction and performing a planarization process to cover the first dielectric layer and the first metal layer (refer to Figure 1 Part D); Pattern the second dielectric layer to expose a part of the first metal layer (refer to Figure 1 Part E); S104. Refer to Figure 1 Part F, continue to deposit a metal along the stacking direction to cover the first metal layer and the second dielectric layer, form a second metal layer, pattern the second metal layer to expose a part of the second dielectric layer, and form a first electrode; S105. Continuing to deposit a third dielectric layer along the stacking direction and performing a planarization process to cover the second dielectric layer and the first electrode (refer to Figure 1 Part G); Pattern the third dielectric layer to form a second groove and expose the first electrode within the second groove (refer to Figure 1 Part H).

[0034] S2. Fabricate the device layer S201. Provide a second substrate and perform a patterning process on the alignment marks thereon (refer to Figure 2 Part A); Deposit a metal on the surface of the second substrate to form a third metal layer, pattern the third metal layer to expose a part of the second substrate, and form a second electrode (refer to Figure 2 Part B); S202. Refer to Figure 2 Part C, pattern the exposed second substrate to remove a part of the thickness of the second substrate to form a support beam so as to form a certain space between the support beam and the circuit layer during bonding. The first support beam preferably includes a first support beam body formed by a part of the second substrate and a second electrode formed at one end of the first support beam body.

[0035] S3. Fabricate the capping layer S301. Refer to Figure 3 Parts A - C, provide a third substrate, deposit a fourth dielectric layer on the surface of the third substrate, and pattern the fourth dielectric layer and the third substrate to form a first groove; S302. Refer to Figure 3 Part D, deposit a getter at the bottom of the first groove; S303. Refer to Figure 3 Part E in the figure, pattern the fourth dielectric layer and the third substrate to form a third groove.

[0036] S4. Bonding S401. Refer to Figure 4 Part A in the figure, bond the first electrode of the circuit layer to the second electrode of the device layer. Since the second substrate has been patterned and part of its thickness has been removed to form a first support beam, there will be no interference between the second substrate and the third dielectric layer during bonding, protecting the electrodes. S402. Refer to Figure 4 Part B in the figure, thin the second substrate of the device layer. S403. Refer to Figure 4 Part C in the figure, pattern the second substrate of the device layer into a comb shape to form a plurality of first channels penetrating the device layer, that is, release the structure of the second substrate to form a mass block as a suspension structure. S404. Refer to Figure 5 Part A in the figure, bond the side of the fourth dielectric layer of the capping layer, that is, the lower surface of the capping layer, to the upper surface of the second substrate (mass block) of the device layer. A circuit area is formed by enclosing between the capping layer and the circuit layer. The first groove and the third groove are respectively connected to the circuit area through the corresponding first channels.

[0037] S405. Refer to Figure 5 Part B in the figure, thin the third substrate of the capping layer and the first substrate of the circuit layer.

[0038] Next, the effects of the MEMS inertial device, its manufacturing method, and its application according to the present invention will be studied through specific embodiments.

[0039] Example 1: Refer to Figure 6 , this example provides a MEMS inertial device, including: a circuit layer, a device layer, and a capping layer.

[0040] Among them, a plurality of second grooves are formed on the upper surface of the circuit layer; a first electrode is provided in the second groove.

[0041] A plurality of support beams corresponding to the first electrodes one by one are provided on the lower surface of the device layer; 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; a plurality of first channels penetrating the device layer are formed in the device layer.

[0042] A plurality of first grooves and a plurality of third grooves arranged at intervals are formed on the lower surface of the capping layer; an getter layer is deposited at the bottom of the first groove. The sum of the number of the first grooves and the third grooves is equal to the number of the first channels.

[0043] The first electrode of the circuit layer is bonded to the second electrode of the device layer, the lower surface of the capping layer is bonded to the upper surface of the device layer, a circuit region is formed by enclosing between the circuit layer and the capping layer, and the first groove and the third groove are respectively communicated with the circuit region through corresponding first channels.

[0044] In this MEMS inertial device provided in this embodiment, by transferring the position of the getter from the circuit layer to the capping layer, the volume of the cavity in the capping layer can be regulated by the cavity depth, without the need to increase the cavity area, thereby making the volume of the MEMS gyroscope smaller, providing more circuit design space for the circuit layer, and reducing the influence brought by parasitic capacitance.

[0045] Embodiment 2: Refer to Figures 1-5 , this embodiment provides a manufacturing method of a MEMS inertial device, which is characterized by including the following steps: S1. Manufacture the circuit layer S101. Provide a wafer as a substrate and perform alignment mark patterning on it. Deposit SiO2 on the substrate surface to form a dielectric layer, and perform patterning to expose part of the substrate.

[0046] S102. Deposit metal Al on the dielectric layer surface to cover the dielectric layer and the substrate, form a metal layer, and perform patterning on the metal layer to expose part of the dielectric layer.

[0047] S103. Continuously deposit SiO2 along the stacking direction and perform planarization processing, so that after covering the previous dielectric layer and metal layer, perform patterning to expose part of the metal layer.

[0048] S104. Continuously deposit metal Al along the stacking direction to cover the metal layer and the SiO2 dielectric layer, and perform patterning to expose part of the SiO2 dielectric layer to form the first electrode.

[0049] S105. Continuously deposit SiO2 along the stacking direction to cover the metal layer and the dielectric layer, and perform planarization and patterning to form a second groove and expose the first electrode in the second groove.

[0050] S2. Manufacture the device layer S201. Provide a silicon wafer as a substrate and perform alignment mark patterning on it. Deposit metal Ge on the substrate surface to form a metal layer, perform patterning on the metal layer, and expose part of the substrate to form the second electrode.

[0051] S202. Perform patterning on the exposed substrate to remove part of the substrate thickness to form a support beam; the support beam includes a support beam body formed by part of the substrate and a second electrode formed at one end of the support beam body.

[0052] S3. Manufacture the capping layer S301. Provide a silicon wafer as a substrate and perform alignment marking patterning on it. Deposit SiO2 on the substrate surface to form a dielectric layer and planarize it. Pattern the dielectric layer and the substrate to form a plurality of first grooves.

[0053] S302. Deposit a getter and pattern it to form a getter layer at the bottom of the first groove.

[0054] S303. Pattern 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 cavity can be adjusted by the cavity depth, and there is no need to increase the cavity area.

[0055] S4. Bonding S401. Bond the first electrode (Al) of the circuit layer to the second electrode (Ge) of the device layer. Since the substrate of the device layer has been patterned, a part of the substrate thickness is removed to form a support beam, and the substrate and the dielectric layer will not interfere during bonding, protecting the electrodes.

[0056] S402. Thin the substrate of the device layer.

[0057] S403. Perform comb-shaped patterning on the substrate of the device layer to form a plurality of first channels penetrating the substrate, and release the structure of the substrate of the device layer to form a mass block as a suspension structure.

[0058] S404. Bond the dielectric layer (SiO2) of the capping layer to the upper surface (Si) of the substrate (mass block) of the device layer. A circuit area is formed by enclosing between the capping layer and the circuit layer. The first groove and the third groove are respectively connected to the circuit area through the corresponding first channels.

[0059] S405. Thin the substrates of the capping layer and the circuit layer.

[0060] The above examples are only illustrative of the present invention and do not constitute a limitation on the protection scope of the present invention. Any design identical or similar to the present invention falls within the protection scope 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 sequentially stacked and bonded; a circuit region is formed by enclosing between the circuit layer and the cap layer; the cap layer is provided with a plurality of first grooves; getter layers are deposited at the bottoms of the plurality of first grooves; and the plurality of first grooves communicate with the circuit region.

2. The MEMS inertial device according to claim 1, characterized in that: The circuit layer is provided with a plurality of second grooves; first electrodes are provided in the second grooves; and the circuit layer is bonded to the device layer through the plurality of first electrodes.

3. The MEMS inertial device according to claim 2, characterized in that: The device layer is provided with a plurality of support beams that are bonded to the first electrodes one by one.

4. The MEMS inertial device according to claim 3, characterized in that: A plurality of first channels penetrating the device layer are formed on the device layer; and the plurality of first grooves communicate with the circuit region through corresponding first channels.

5. The MEMS inertial device according to claim 3, wherein: 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; and the second electrode is bonded to the first electrode.

6. The manufacturing method of the MEMS inertial device according to any one of claims 1-5, characterized in that It includes the following steps: S1. Manufacture the circuit layer; S2. Manufacture the device layer; S3. Manufacture the cap layer: perform patterning on one side surface of the cap layer to form a plurality of first grooves; deposit a getter in the bottoms of the plurality of first grooves; S4. Bonding: bond the circuit layer and the device layer; Perform comb-shaped patterning on the device layer to form a plurality of first channels penetrating the device layer; bond the cap layer and the device layer so that the first grooves communicate with the corresponding first channels respectively.

7. The manufacturing method of the MEMS inertial device according to claim 6, wherein, The step S1 includes: S101. Provide a first substrate, deposit a first dielectric layer on the surface of the first substrate, and perform patterning on the first dielectric layer to expose part of the first substrate; S102. Deposit a first metal layer, and perform patterning on the first metal layer to expose part of the first dielectric layer; S103. Deposit a second dielectric layer, and perform patterning on the second dielectric layer to expose part of the first metal layer; S104. Deposit a second metal layer to cover the first metal layer and the second dielectric layer, and perform patterning on the second metal layer to form a first electrode; S105. Deposit a third dielectric layer to cover the second dielectric layer and the first electrode, and perform patterning on the third dielectric layer to expose the first electrode.

8. The manufacturing method of the MEMS inertial device according to claim 6, characterized in that The step S2 includes: S201. Provide a second substrate, deposit a third metal layer on the surface of the second substrate, and perform patterning on the third metal layer to expose part of the second substrate; S202. Perform patterning on the exposed second substrate to remove part of the thickness of the second substrate to form a support beam.

9. The manufacturing method of the MEMS inertial device according to claim 6, wherein The step S3 includes: S301. Provide a third substrate, deposit a fourth dielectric layer on the surface of the third substrate, and perform patterning on the fourth dielectric layer and the third substrate to form a first groove; S302. Deposit a getter at the bottom of the first groove.

10. The manufacturing method of the MEMS inertial device according to claim 9, characterized in that, The step S3 further includes: S303. Perform patterning on the fourth dielectric layer and the third substrate to form a third groove.

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