A wafer-level MEMS inertial sensor with isolation grooves and a preparation method thereof

Abstract

The present invention relates to a wafer-level MEMS inertial sensor with isolation grooves and a preparation method thereof. The MEMS inertial sensor includes a substrate layer, a MEMS inertial sensor structure layer, and a cover plate arranged in sequence from bottom to top. A plurality of first grooves and isolation grooves are formed on the upper surface of the substrate layer. A plurality of through holes are formed on the MEMS inertial sensor structure layer as suspension structures. A second groove is formed on the lower surface of the cover plate, and a getter material is adsorbed in the second groove. The upper surface of the substrate layer is bonded to the lower surface of the MEMS inertial sensor structure layer by a bonding process, and the upper surface of the MEMS inertial sensor structure layer is bonded to the lower surface of the cover plate by a bonding process. The present invention uses a bonding process for multi-layer structure packaging of the MEMS inertial sensor to achieve wafer-level packaging of the MEMS inertial sensor.

Description

Technical Field

[0001] The present invention relates to the fields of microelectromechanical system processing and inertial navigation, and particularly to a wafer-level MEMS inertial sensor with isolation grooves and a preparation method thereof. Background Art

[0002] In the MEMS (Micro-Electro-Mechanical System) process, the gas damping during the movement of many micro-mechanical components can be reduced through vacuum packaging technology, the quality factor of MEMS devices can be improved, and further the device performance of MEMS inertial sensor chips can be enhanced. The wafer-level packaging technology, which has the advantages of low batch production cost and small device size, has great commercial value. Therefore, how to achieve the wafer-level packaging of MEMS inertial sensor chips has become a technical problem to be solved urgently. Summary of the Invention

[0003] The purpose of the present invention is to provide a wafer-level MEMS inertial sensor with isolation grooves and a preparation method thereof to achieve the wafer-level packaging of MEMS inertial sensors.

[0004] To achieve the above purpose, the present invention provides the following solutions:

[0005] The present invention provides a wafer-level MEMS inertial sensor with isolation grooves, which is characterized in that the MEMS inertial sensor includes a substrate layer, a MEMS inertial sensor structure layer, and a cover plate arranged in sequence from bottom to top;

[0006] A plurality of first grooves are formed on the upper surface of the substrate layer; isolation grooves penetrating through the substrate layer are formed at the positions of the first grooves, and isolation materials are filled in the isolation grooves;

[0007] A plurality of through holes penetrating through the MEMS inertial sensor structure layer are formed on the MEMS inertial sensor structure layer as suspension structures;

[0008] A second groove is formed on the lower surface of the cover plate, and a getter material is adsorbed in the second groove;

[0009] The upper surface of the substrate layer and the lower surface of the MEMS inertial sensor structure layer are connected by a bonding process. After connection, each of the first grooves is aligned with a different one of the through holes;

[0010] The upper surface of the MEMS inertial sensor structure layer and the lower surface of the cover plate are connected by a bonding process. After connection, the second groove covers all the through holes on the MEMS inertial sensor structure layer.

[0011] Optionally, an electrical isolation layer and electrodes are provided on the lower surface of the substrate layer;

[0012] The electrode is led out at a position on the lower surface of the substrate layer where no isolation groove is formed.

[0013] Optionally, the diameter of the isolation groove is 2 μm to 8 μm, the depth of the isolation groove is 80 μm to 120 μm, the depth of the first groove is 10 μm to 50 μm; the thickness of the MEMS inertial sensor structure layer is 40 μm to 120 μm; the depth of the second groove is 10 μm to 50 μm.

[0014] A preparation method of a wafer-level MEMS inertial sensor with isolation grooves, the preparation method comprising the following steps:

[0015] Prepare the above-mentioned substrate layer;

[0016] Adopt a bonding process to bond an intermediate structure layer on the upper surface of the substrate layer;

[0017] Process the intermediate structure layer to form a MEMS inertial sensor structure layer;

[0018] Prepare a cover plate;

[0019] Adopt a bonding process to bond the cover plate on the upper part of the MEMS inertial sensor structure layer.

[0020] Optionally, the specific steps of preparing the substrate layer include:

[0021] Obtain a substrate wafer;

[0022] Adopt a photolithography process to define a first preset position on the upper surface of the substrate wafer; the first preset position is the position of the isolation groove on the upper surface of the substrate layer;

[0023] Adopt an etching process to form an isolation groove at the first preset position;

[0024] Adopt a CVD (Chemical Vapor Evaporation) process to fill an isolation material in the isolation groove;

[0025] Adopt a photolithography and / or etching process to define a second preset position on the upper surface of the substrate wafer provided with the isolation groove; the second preset position is the position of the first groove on the upper surface of the substrate layer;

[0026] Adopt an etching process to form a first groove at the second preset position as an anchor pattern for bonding with the intermediate structure layer.

[0027] Optionally, after adopting an etching process to form a first groove at the second preset position as an anchor pattern for bonding with the intermediate structure layer, the following steps are further included:

[0028] Thin the substrate wafer from the lower surface thereof by a thinning process until the isolation groove is exposed;

[0029] Prepare an electrical isolation layer on the lower surface of the thinned substrate wafer by a CVD process;

[0030] Define electrode lead-out holes on the electrical isolation layer by a photolithography and / or etching process;

[0031] Deposit a metal electrode material layer on the lower surface of the electrical isolation layer and within the electrode lead-out holes by a PVD (Physical Vapor Deposition) process;

[0032] Etch the metal electrode material layer by a photolithography and / or etching process to form electrodes.

[0033] Optionally, process the intermediate structure layer to form the MEMS inertial sensor structure layer in Claim 1, specifically including:

[0034] Thin the thickness of the intermediate structure layer to a preset thickness by a thinning process; the preset thickness is the thickness of the MEMS inertial sensor structure layer;

[0035] Define a first bonding pattern on the upper surface of the thinned intermediate structure layer by a PVD, photolithography, and / or etching process;

[0036] Open through holes in the thinned intermediate structure layer by a photolithography and / or etching process as suspension structures.

[0037] Optionally, prepare a cover plate, specifically including:

[0038] Define a second bonding pattern on the lower surface of the top layer material by a PVD, photolithography, and / or etching process;

[0039] Open a second groove on the lower surface of the top layer material by a photolithography and / or etching process.

[0040] Optionally, bond the cover plate to the upper part of the MEMS inertial sensor structure layer by a bonding process, specifically:

[0041] Perform matching bonding according to the first bonding pattern and the second bonding pattern using a bonding material.

[0042] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0043] The present invention discloses a wafer-level MEMS inertial sensor with isolation grooves and a preparation method thereof. The MEMS inertial sensor includes a substrate layer, a MEMS inertial sensor structure layer, and a cover plate arranged in sequence from bottom to top. A plurality of first grooves are formed on the upper surface of the substrate layer. Isolation grooves penetrating through the substrate layer are formed at the positions of the first grooves. A plurality of through holes penetrating through the MEMS inertial sensor structure layer are formed on the MEMS inertial sensor structure layer as suspension structures. A second groove is formed on the lower surface of the cover plate, and a getter material is adsorbed in the second groove. The upper surface of the substrate layer and the lower surface of the MEMS inertial sensor structure layer are connected by a bonding process. After connection, each of the first grooves is aligned with a different through hole. The upper surface of the MEMS inertial sensor structure layer and the lower surface of the cover plate are connected by a bonding process. After connection, the second groove covers all the through holes on the MEMS inertial sensor structure layer. The present invention uses a bonding process for multi-layer structure packaging of the MEMS inertial sensor to achieve wafer-level packaging of the MEMS inertial sensor. Moreover, based on the sealing cavity electrode isolation and lead-out technology, the present invention processes isolation grooves on the substrate layer and fills them to achieve mechanical connection and electrode isolation, and then forms multi-layer vertical interconnection through a bonding process to achieve electrode lead-out. By adopting a multi-layer bonding process and a getter preparation and activation scheme, long-term vacuum degree maintenance of the device is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the following described drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0045] Figure 1 It is a schematic diagram of the structure of a wafer-level MEMS inertial sensor with isolation grooves provided by the present invention;

[0046] Figure 2 It is a flowchart of a preparation method of a wafer-level MEMS inertial sensor with isolation grooves provided by the present invention; Figure 2(a), (b), (c), (d), (e), (f), and (g) in [the figure] are respectively: a front sectional view of a substrate wafer filled with isolation material, a front sectional view of a substrate wafer provided with a first groove, a front sectional view of a first intermediate structure obtained after bonding an intermediate structure layer on the upper surface of the substrate layer, a front sectional view of a second intermediate structure obtained after processing the intermediate structure layer of the first intermediate structure, a front sectional view of a cover plate, a front sectional view of a third intermediate structure obtained after bonding the cover plate on the upper part of the MEMS inertial sensor structure layer, and a front sectional view of a wafer-level MEMS inertial sensor with isolation grooves. Detailed implementation manner

[0047] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0048] The purpose of the present invention is to provide a wafer-level MEMS inertial sensor with isolation grooves and a preparation method thereof to achieve wafer-level packaging of the MEMS inertial sensor.

[0049] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation manners.

[0050] Embodiment 1

[0051] Embodiment 1 of the present invention provides a wafer-level MEMS inertial sensor with isolation grooves. As Figure 1 shown, the MEMS inertial sensor includes: a substrate layer 1, a MEMS inertial sensor structure layer 3, and a cover plate 4.

[0052] The substrate layer 1 is a substrate wafer with isolation grooves and vertical interconnections. The specific structure is that a plurality of first grooves 9 are opened on the upper surface of the substrate layer 1; isolation grooves 2 penetrating the substrate layer are opened at the positions of the first grooves 9, and the isolation grooves are filled with isolation material.

[0053] An electrical isolation layer 7 and electrodes 8 are provided on the lower surface of the substrate layer 1; the electrodes 8 are led out at positions on the lower surface of the substrate layer 1 where the isolation grooves 2 are not opened.

[0054] The MEMS inertial sensor structure layer 3 is a MEMS inertial sensor wafer with a suspension structure. The specific structure is that a plurality of through holes 10 penetrating the MEMS inertial sensor structure layer are opened on the MEMS inertial sensor structure layer 3 as the suspension structure.

[0055] The cover plate 4 is a wafer with a cavity (which is the second groove 11 before being bonded to the MEMS inertial sensor structural layer 3) and a getter material 5 attached in the cavity, and is the cap for realizing wafer-level vacuum packaging of the MEMS inertial sensor. The cover plate 4 is bonded to the MEMS inertial sensor structural layer 3 using a bonding material 6.

[0056] Exemplarily, the diameter of the isolation groove 2 is 2 μm to 8 μm, the depth of the isolation groove 2 is 80 μm to 120 μm, the depth of the first groove 9 is 10 μm to 50 μm; the thickness of the MEMS inertial sensor structural layer 3 is 40 μm to 120 μm; the depth of the second groove 11 is 10 μm to 50 μm.

[0057] Embodiment 2

[0058] Embodiment 2 of the present invention provides a method for manufacturing a wafer-level MEMS inertial sensor with isolation grooves. The manufacturing method processes isolation grooves on the substrate layer and performs a filling process to achieve isolation technology; and then forms a multi-layer vertical interconnection process technology through a bonding process.

[0059] As Figure 2 shown, the manufacturing method includes the following steps:

[0060] 1) As Figure 2 shown in (a) in

[0061] Perform a photolithography process on the substrate wafer to define the position of the isolation groove, open the groove through a deep etching process to form a "V"-shaped isolation groove, and then fill the groove by depositing an isolation material and a filling material through CVD (Chemical Vapor Deposition).

[0062] 2) As Figure 2 shown in (b) in

[0063] Locate the first groove through photolithography and etching processes, and form the first groove using an etching process.

[0064] 3) As Figure 2 shown in (c) in

[0065] Connect the intermediate structure layer and the substrate layer through a bonding process to achieve a stable and reliable bonded wafer, and at this time, obtain the first intermediate structure as shown in (c) in Figure 2

[0066] 4) As Figure 2 shown in (d) in

[0067] ​The thickness of the middle MEMS inertial sensor layer is achieved through a thinning process, and the first bonding pattern is defined by PVD (Physical Vapor Deposition), photolithography, and etching processes. The preparation of the MEMS inertial sensor pattern is achieved through a photolithography process, and then the MEMS inertial sensor layer is formed by a deep etching process, finally forming a second intermediate structure, namely the MEMS inertial sensor body with isolation grooves.

[0068] 5) As shown in (e) of Figure 2 the preparation of the top cover plate.

[0069] The second bonding pattern is defined by PVD (Physical Vapor Deposition), photolithography, and etching processes. The second groove of the cover plate is formed through photolithography and etching processes, and then a getter material is attached to the second groove through a PVD process, and the cover plate is made.

[0070] 6) As shown in (f) of Figure 2 forming a multi-layer structure connection.

[0071] Using a bonding process, the second intermediate structure is connected to the cover plate to form a "sandwich" type structure, namely Figure 2 the third intermediate structure shown in (f) of

[0072] 7) As shown in (g) of Figure 2 the preparation of the multi-layer vertical interconnection lead-out electrode.

[0073] The substrate wafer is thinned through a thinning process to expose the isolation grooves, and then via holes are defined through CVD and photolithography processes. The lead-out of the electrodes is achieved through PVD and photolithography processes. Finally, a wafer-level vacuum packaged MEMS inertial sensor with multi-layer vertical interconnection, isolation, and vacuum degree is prepared.

[0074] According to the specific embodiments provided by the present invention, the following technical effects are disclosed by the present invention:

[0075] The present invention uses the processing method of microfabrication technology to achieve inertial devices with high precision, miniaturization, low power consumption, low cost, complex environment adaptability, and long-term stability.

[0076] In this specification, each embodiment is described in a progressive manner. The key point of each embodiment is to illustrate the differences from other embodiments. The same or similar parts among the embodiments can be referred to each other.

[0077] Specific examples are applied in this article to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A wafer-level MEMS inertial sensor with isolation grooves, Characterized in that, The MEMS inertial sensor includes a substrate layer, a MEMS inertial sensor structure layer, and a cover plate arranged in sequence from bottom to top; A plurality of first grooves are formed on the upper surface of the substrate layer; isolation grooves penetrating through the substrate layer are formed at the positions of the first grooves, and the isolation grooves are filled with isolation materials; A plurality of through holes penetrating through the MEMS inertial sensor structure layer are formed on the MEMS inertial sensor structure layer as suspension structures; A second groove is formed on the lower surface of the cover plate, and a getter material is adsorbed in the second groove; The upper surface of the substrate layer is connected to the lower surface of the MEMS inertial sensor structure layer by a bonding process. After connection, each of the first grooves is aligned with a different one of the through holes; The upper surface of the MEMS inertial sensor structure layer is connected to the lower surface of the cover plate by a bonding process. After connection, the second groove covers all the through holes on the MEMS inertial sensor structure layer.

2. The wafer-level MEMS inertial sensor with isolation grooves according to claim 1, Characterized in that, An electrical isolation layer and electrodes are provided on the lower surface of the substrate layer; The electrodes are led out at positions on the lower surface of the substrate layer where no isolation grooves are formed.

3. The wafer-level MEMS inertial sensor with isolation grooves according to claim 1, Characterized in that, The diameter of the isolation groove is 2 μm to 8 μm, the depth of the isolation groove is 80 μm to 120 μm, and the depth of the first groove is 10 μm to 50 μm; the thickness of the MEMS inertial sensor structure layer is 40 μm to 120 μm; the depth of the second groove is 10 μm to 50 μm.

4. A preparation method for a wafer-level MEMS inertial sensor with isolation grooves, Characterized in that, The preparation method includes the following steps: Preparing the substrate layer in claim 1; Bonding an intermediate structure layer on the upper surface of the substrate layer by a bonding process; Processing the intermediate structure layer to form the MEMS inertial sensor structure layer in claim 1; Preparing the cover plate in claim 1; Bonding the cover plate on the upper part of the MEMS inertial sensor structure layer by a bonding process.

5. The preparation method for a wafer-level MEMS inertial sensor with isolation grooves according to claim 4, Characterized in that, The specific steps for preparing the substrate layer include: Obtaining a substrate wafer; Defining a first preset position on the upper surface of the substrate wafer by a photolithography process; the first preset position is the position of the isolation groove in claim 1 on the upper surface of the substrate layer; Opening an isolation groove at the first preset position by an etching process; Defining a second preset position on the upper surface of the substrate wafer with an isolation groove by a photolithography and / or etching process; the second preset position is the position of the first groove in claim 1 on the upper surface of the substrate layer; Opening a first groove at the second preset position by an etching process as an anchor pattern for bonding with the intermediate structure layer.

6. The preparation method for a wafer-level MEMS inertial sensor with isolation grooves according to claim 5, It is characterized in that An etching process is used to open a first groove at the second preset position as an anchor pattern for bonding with the intermediate structure layer. After that, it further includes: The substrate wafer is thinned from the lower surface of the substrate wafer by a thinning process until the isolation groove is exposed; A CVD process is used to prepare an electrical isolation layer on the lower surface of the thinned substrate wafer; A photolithography and / or etching process is used to define electrode lead-out holes on the electrical isolation layer; A PVD process is used to deposit a metal electrode material layer on the lower surface of the electrical isolation layer and in the electrode lead-out holes; A photolithography and / or etching process is used to etch the metal electrode material layer to form electrodes.

7. The method for fabricating a wafer-level MEMS inertial sensor with an isolation groove according to claim 4, It is characterized in that The intermediate structure layer is processed to form the MEMS inertial sensor structure layer in claim 1, specifically including: The thickness of the intermediate structure layer is thinned to a preset thickness by a thinning process; the preset thickness is the thickness of the MEMS inertial sensor structure layer in claim 1; A PVD, photolithography, and / or etching process is used to define a first bonding pattern on the upper surface of the thinned intermediate structure layer; A photolithography and / or etching process is used to open the through hole in claim 1 on the thinned intermediate structure layer as a suspension structure.

8. The method for fabricating a wafer-level MEMS inertial sensor with an isolation groove according to claim 7, It is characterized in that The cover plate in claim 1 is fabricated, specifically including: A PVD, photolithography, and / or etching process is used to define a second bonding pattern on the lower surface of the top layer material; A photolithography and / or etching process is used to open the second groove in claim 1 on the lower surface of the top layer material.

9. The method for fabricating a wafer-level MEMS inertial sensor with an isolation groove according to claim 8, It is characterized in that A bonding process is used to bond the cover plate on the upper part of the MEMS inertial sensor structure layer, specifically: A bonding material is used for matching bonding according to the first bonding pattern and the second bonding pattern.

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