Inertial measurement unit and manufacturing method therefor

Abstract

An inertial measurement unit and a manufacturing method therefor. The inertial measurement unit comprises: a first substrate (1); a dielectric layer (2), wherein the dielectric layer (2) is stacked on the first substrate (1), and notches (15) are formed on the dielectric layer (2); a first conductive layer (3), wherein the first conductive layer (3) is stacked on the dielectric layer (2); a second conductive layer (5), wherein the second conductive layer (5) is supported on the first conductive layer (3) by means of support portions (7); a second substrate (9), wherein the second substrate (9) covers the second conductive layer (5) by means of a bonding structure (8), a sealed space is formed between the second substrate (9) and the first substrate (1), the sealed space comprises a plurality of separated chambers (14), and the chambers (14) have different chamber pressures; an exhaust channel (12), communicated with at least one chamber (14), wherein the exhaust channel (12) is used for communicating the chamber (14) with the outside; and a sealing portion, used for sealing the exhaust channel (12). A plurality of chambers (14) having different chamber pressures are provided on a single wafer, which is conducive to manufacturing of an inertial measurement unit in which two or more inertial sensors are integrated.

Description

An inertial measurement unit and its fabrication method Technical Field

[0001] This invention relates to the field of microelectromechanical systems (MEMS) technology, and in particular to an inertial measurement unit and its fabrication method. Background Technology

[0002] Using two or more inertial sensors with different cavity pressures on a single component module is commonly referred to as an inertial measurement unit (IMU). An inertial measurement unit can measure acceleration and angular velocity within a single component module.

[0003] Traditional inertial measurement units consist of separate inertial sensor chips with different pressures, fabricated individually on different wafers, and then placed together as a single component.

[0004] This method doubles the manufacturing materials and cycle time required to fabricate a single inertial measurement unit with two different cavity pressures. The cost and resources increase further when multiple inertial sensors with different cavity pressures need to be assembled in a single inertial measurement unit. Technical issues

[0005] The purpose of this invention is to provide an inertial sensor and its fabrication method to solve the technical problems in the prior art. It can fabricate two or more inertial sensors with different cavity pressures on a single wafer. Technical solutions

[0006] This invention provides an inertial measurement unit, comprising:

[0007] First substrate;

[0008] A dielectric layer is stacked on the first substrate, and a notch is formed on the dielectric layer;

[0009] A first conductive layer is stacked on the dielectric layer, and the first conductive layer has a plurality of first openings.

[0010] A second conductive layer is supported on the first conductive layer by a support portion, and the second conductive layer has a plurality of second openings.

[0011] The second substrate is bonded to the second conductive layer by a bonding structure, and a sealed space is formed between the second substrate and the first substrate. The sealed space includes multiple phase-separated chambers, and the chamber pressures of each chamber are different.

[0012] An exhaust passage is provided, connecting to at least one of the chambers, the exhaust passage being used to connect the chambers to the outside;

[0013] A sealing section is used to seal off the exhaust passage.

[0014] In the inertial measurement unit described above, preferably, the exhaust channel includes a first channel segment and a second channel segment, one end of the first channel segment is connected to the outside, the other end of the first channel segment is connected to one end of the second channel segment, and the other end of the second channel segment is connected to the corresponding chamber.

[0015] In the inertial measurement unit described above, preferably, the second channel segment includes a plurality of sequentially connected exhaust sub-channels.

[0016] In the inertial measurement unit described above, preferably, the first channel segment and the second channel segment intersect perpendicularly.

[0017] In the inertial measurement unit described above, preferably, the number of chambers is set to n, where n≥2, and the number of chambers connected to the exhaust channel is n-1 or n.

[0018] In the inertial measurement unit described above, preferably, the sealed space includes a first chamber and a second chamber separated by phase, the cavity pressure of the first chamber is greater than the cavity pressure of the second chamber, the exhaust channel is formed in the second substrate and the bonding structure, one end of the exhaust channel forms a first opening on the outer wall surface of the second substrate, the other end of the exhaust channel forms a second opening on the inner wall surface of the bonding structure, and the exhaust channel communicates with the first chamber through the second opening.

[0019] In the inertial measurement unit described above, preferably, the first opening is formed on the top surface of the second substrate, and the closure covers the top surface of the second substrate to close the first opening.

[0020] In the inertial measurement unit described above, preferably, the bonding structure includes a first bonding layer and a second bonding layer bonded together, the first bonding layer being stacked on top of the second conductive layer, and the second bonding layer being stacked on the bottom of the second substrate.

[0021] In the inertial measurement unit described above, preferably, the bottom surface of the second substrate is provided with a plurality of connecting blocks, the connecting blocks being connected to the bonding structure, and grooves being formed between adjacent connecting blocks.

[0022] Secondly, the present invention provides a method for preparing an inertial measurement unit, for use in the aforementioned inertial measurement unit, the inertial measurement unit comprising:

[0023] First substrate;

[0024] A dielectric layer is stacked on the first substrate, and a notch is formed on the dielectric layer;

[0025] A first conductive layer is stacked on the dielectric layer, and the first conductive layer has a plurality of first openings.

[0026] A second conductive layer is supported on the first conductive layer by a support portion, and the second conductive layer has a plurality of second openings.

[0027] The second substrate is bonded to the second conductive layer by a bonding structure, and a sealed space is formed between the second substrate and the first substrate. The sealed space includes multiple phase-separated chambers, and the chamber pressures of each chamber are different.

[0028] An exhaust passage is provided, connecting to at least one of the chambers, the exhaust passage being used to connect the chambers to the outside;

[0029] A sealing section is used to seal off the exhaust passage;

[0030] The preparation method includes the following steps:

[0031] Forming the first substrate;

[0032] The dielectric layer and the first conductive layer are formed on the first substrate, the notch is formed on the dielectric layer, and the first opening is formed on the first conductive layer;

[0033] A second conductive layer is formed on the first conductive layer, and a first bonding layer is formed on the second conductive layer;

[0034] The second opening and the support portion are formed on the second conductive layer;

[0035] Forming a second substrate;

[0036] A second bonding layer is formed on the second substrate;

[0037] A groove is formed on the second substrate;

[0038] The first bonding layer and the second bonding layer are bonded together at high temperature to form a bonding structure. The second substrate and the first substrate enclose a sealed space, which includes multiple phase-separated chambers.

[0039] An exhaust channel is formed within the second substrate and the bonding structure to release air from at least one of the chambers;

[0040] A sealing portion is deposited on the second substrate to seal the exhaust channel;

[0041] Finished product forming. Beneficial effects

[0042] Compared to existing technologies, this invention achieves multiple chambers with different chamber pressures on a single wafer by setting at least one exhaust channel connecting at least one chamber to draw air out of the exhaust channel and escape from the chamber, and then sealing the exhaust channel with a sealing part. This facilitates the manufacturing of inertial measurement units that assemble two or more inertial sensors together, thereby allowing inertial measurement units to be manufactured differently according to different required functions and performance specifications. Since the materials and manufacturing processes of inertial sensors are similar, this method reduces the manufacturing cycle time, materials, and costs per unit of inertial measurement unit. Attached Figure Description

[0043] Figure 1 is a cross-sectional schematic diagram of the inertial sensor according to an embodiment of the present invention;

[0044] Figures 2a-2c are schematic cross-sectional views along the AA direction of Figure 1 (exhaust channels with various structures);

[0045] Figures 3a-3j are flowcharts illustrating the fabrication process of the inertial sensor according to the embodiments provided by the present invention.

[0046] Explanation of reference numerals in the attached drawings: 1-First substrate, 2-Dielectric layer, 3-First conductive layer, 4-First opening, 5-Second conductive layer, 6-Second opening, 7-Support portion, 71-Support block, 8-Bonding structure, 81-First bonding layer, 82-Second bonding layer, 9-Second substrate, 10-Connecting block, 11-Groove, 12-Exhaust channel, 121-First channel segment, 122-Second channel segment, 123-Exhaust sub-channel, 13-Sealing portion, 14-Cavity, 141-First chamber, 142-Second chamber, 15-Notch. The best embodiment of the present invention

[0047] The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0048] As shown in Figure 1, an embodiment of the present invention provides an inertial sensor, which, from bottom to top, comprises a first substrate 1, a dielectric layer 2, a first conductive layer 3, a second conductive layer 5, and a second substrate 9, wherein:

[0049] The first substrate 1 is a semiconductor substrate, such as a silicon substrate. In one feasible embodiment, the first substrate 1 is circular. Those skilled in the art will know that the first substrate 1 can also be other shapes, such as square, etc., which are not limited here.

[0050] A dielectric layer 2 is stacked on a first substrate 1. The shape of the dielectric layer 2 is adapted to the shape of the first substrate 1. The dielectric layer 2 is used to support the first conductive layer 3 and to achieve electrical isolation between the first conductive layer 3 and the first substrate 1. A notch 15 is formed on the dielectric layer 2. In one feasible embodiment, the material of the dielectric layer 2 is silicon dioxide.

[0051] The first conductive layer 3 is stacked on the dielectric layer 2. The shape of the first conductive layer 3 is adapted to the shape of the dielectric layer 2. The first conductive layer 3 has a plurality of first openings 4. The first conductive layer 3 is made of a conductive material, such as polycrystalline silicon.

[0052] The second conductive layer 5 is supported on the first conductive layer 3 by the support portion 7. The support portion 7 is used to support the second conductive layer 5, so that there is a gap between the second conductive layer 5 and the first conductive layer 3 to provide space for the second conductive layer 5 to deform. The second conductive layer 5 has a plurality of second openings 6. The second conductive layer 5 is a conductive material, such as polycrystalline silicon.

[0053] The second substrate 9 is covered onto the second conductive layer 5 by a bonding structure 8. The bonding structure 8 includes a first bonding layer 81 and a second bonding layer 82 that are bonded together. The first bonding layer 81 is stacked on top of the first conductive layer 3, and the second bonding layer 82 is stacked on the bottom of the second conductive layer 5. Both the first bonding layer 81 and the second bonding layer 82 are made of metal to form a metal hot-press bonding.

[0054] The second substrate 9 is a semiconductor substrate, such as a silicon substrate. In one feasible embodiment, the second substrate 9 is circular. Those skilled in the art will know that the second substrate 9 can also be other shapes, such as square, etc., which are not limited here. The second substrate 9 and the first substrate 1 enclose a sealed space, thereby preventing the internal structure of the inertial sensor from being disturbed by the external environment, facilitating the control of the air pressure in the cavity, and improving the working stability.

[0055] The sealed space includes multiple separated chambers 14, each with a different pressure. The number of chambers 14 is at least two. The number of chambers 14 and the pressure of each chamber 14 can be determined according to actual needs and are not limited here. In the embodiment provided in this application, an exhaust channel 12 is provided. The exhaust channel 12 can be located on any wall of the chamber 14. One end of the exhaust channel 12 is connected to the inside of the chamber 14, and the other end is connected to the outside. In the embodiment provided in this application, the exhaust channel 12 is connected to at least one chamber 14. Specifically, the number of chambers 14 is set to n (n≥2), and the number of chambers 14 connected to the exhaust channel 12 is n-1 or n.

[0056] For example, when there are two chambers 14, an exhaust channel 12 can be set in only one chamber 14 to exhaust the corresponding chamber 14, drawing air out of the exhaust channel 12 and escaping from the chamber 14, while the other chamber 14 maintains the initial chamber pressure, thus achieving multiple chambers 14 with different chamber pressures on a single wafer. Alternatively, an exhaust channel 12 can be set in both chambers 14, so that the chamber pressures in the two chambers 14 are different from the initial chamber pressures, and the chamber pressures in the two chambers 14 are also different.

[0057] Each chamber 14 connected to an exhaust channel 12 may have one or more exhaust channels 12, which is not limited here. With multiple exhaust channels 12, the air in the chamber 14 is discharged faster, but it will also cause the structure to be more complex and the sealing stability to be poor. In the embodiment provided in this application, each chamber 14 connected to an exhaust channel 12 has one exhaust channel 12.

[0058] After the cavity pressure in each chamber 14 reaches the preset value, the exhaust channel 12 is sealed by the sealing part 13, so that each chamber 14 is restored to a sealed cavity, improving the working stability. The sealing part 13 is made of dielectric or conductive material, which is not limited here.

[0059] In the embodiments provided in this application, in order to prevent the sealing material used for sealing from being deposited into the exhaust channel 12 when the sealing part 13 seals the exhaust channel 12, the exhaust channel 12 includes a first channel segment 121 and a second channel segment 122. One end of the first channel segment 121 is connected to the outside, and the other end of the first channel segment 121 is connected to one end of the second channel segment 122. The other end of the second channel segment 122 is connected to the corresponding chamber 14. When the sealing part 13 seals the exhaust channel 12, the deposited material of the sealing part 13 flows along the first channel segment 121. Since the extension directions of the first channel segment 121 and the second channel segment 122 are not parallel, the deposited material of the sealing part 13 will hinder the flow of material at the bend, so as to prevent the deposited material of the sealing part 13 from flowing into the chamber 14.

[0060] Furthermore, the second channel segment 122 includes multiple sequentially connected exhaust sub-channels 123. The multiple exhaust sub-channels 123 are located in the same plane, so that multiple bends can be formed at adjacent exhaust sub-channels 123, which can more effectively hinder the flow of deposited material in the closed part 13 and prevent the deposited material from depositing into the chamber 14 and affecting the performance of the device.

[0061] Figures 2a-2c exemplify the structure and number of multiple exhaust sub-channels 123 within the second channel segment 122. Those skilled in the art will understand that the number and shape of the exhaust sub-channels 123 can be determined according to actual needs and are not limited here.

[0062] In one feasible implementation, the first channel segment 121 and the second channel segment 122 intersect perpendicularly. When the deposited material in the closed part 13 flows to the bend, it comes into contact with the wall at the bend. Since the two adjacent walls intersect perpendicularly, the walls do not provide the deposited material with a frictional force to continue flowing. The deposited material is easy to accumulate at the bend, and the obstruction effect on the deposited material is better.

[0063] In the embodiments provided in this application, referring to Figures 1, 2a to 2c, the sealed space has two separated chambers 14, namely a first chamber 141 and a second chamber 142. The first chamber 141 is a high-pressure chamber, and the second chamber 142 is a low-pressure chamber. The pressure in the first chamber 141 is greater than the pressure in the second chamber 142. An exhaust channel 12 is formed in the second substrate 9 and the bonding structure 8. In one feasible embodiment, the main body of the first channel segment 121 is located in the second substrate 9, and the second channel segment 122 is located in the bonding structure 8. The connection between the first channel segment 121 and the second channel segment 122 is located at the bonding structure 8. One end of the exhaust channel 12 forms a first opening on the outer wall surface of the second substrate 9. The first opening is formed at the end of the first channel segment 121. The other end of the exhaust channel 12 forms a second opening on the inner wall surface of the bonding structure 8. The second opening is formed at the end of the second channel segment 122. The exhaust channel 12 communicates with the first chamber 141 through the second opening.

[0064] Furthermore, the first channel segment 121 extends along the height direction of the inertial measurement unit, and the second channel segment 122 extends along the horizontal direction. The first channel segment 121 and the second channel segment 122 intersect perpendicularly. The first opening is formed on the top surface of the second substrate 9, which facilitates the deposition and forming of the sealing part 13. The sealing part 13 covers the top surface of the second substrate 9 to close the first opening. The sealing part 13 is a film structure formed by depositing dielectric or conductive material. After the cavity pressure of the first chamber 141 reaches the preset requirement, a layer of dielectric or conductive material is deposited on the top surface of the second substrate 9, so that each chamber 14 returns to a sealed cavity and improves the working stability.

[0065] In one feasible implementation, referring to FIG1, the support part 7 includes a plurality of support blocks 71. The bottom end of the support block 71 is connected to the first conductive layer 3, and the top end of the support block 71 is connected to the second conductive layer 5. A cavity is formed between adjacent support blocks 71. The second conductive layer 5 located above the cavity is a movable mass block. When the movable mass block is displaced, the distance between it and the first conductive layer 3 is changed, thereby the capacitance signal in the corresponding direction can be detected to realize the detection of inertia.

[0066] In the embodiments provided in this application, a plurality of connecting blocks 10 are protruding from the bottom surface of the second substrate 9. The connecting blocks 10 are connected to the bonding structure 8, and grooves 11 are formed between adjacent connecting blocks 10. Each chamber 14 corresponds to a groove 11 to provide space for the second conductive layer 5 to be displaced.

[0067] Based on the above embodiments and referring to Figures 3a-3c, the present invention also provides a method for fabricating an inertial sensor, the method comprising the following steps:

[0068] S101: Referring to FIG3a, a first substrate 1 is formed.

[0069] S102: Referring to FIG3b, a dielectric layer 2 and a first conductive layer 3 are formed on a first substrate 1, a notch 15 is formed on the dielectric layer 2, and a first opening 4 is formed on the first conductive layer 3;

[0070] In this step, a dielectric layer 2 is formed on the first substrate 1 by deposition, a notch 15 is formed on the dielectric layer 2, a first conductive layer 3 is formed on the dielectric layer 2 by deposition, a resist layer is formed on the surface of the first conductive layer 3 by deposition, the resist layer is patterned by photolithography to form a mask, and the first conductive layer 3 is etched through the mask to form a first opening 4 penetrating the first conductive layer 3.

[0071] S103: Referring to FIG3c, a second conductive layer 5 is formed on the first conductive layer 3, and a first bonding layer 81 is formed on the second conductive layer 5;

[0072] In this step, a first bonding layer 81 is formed on the surface of the second conductive layer 5, for example, by deposition and etching.

[0073] S104: Referring to FIG3d, a second opening 6 and a support portion 7 are formed on the second conductive layer 5;

[0074] In this step, a resist layer is formed on the surface of the second conductive layer 5, the resist layer is patterned using a photolithography process to form a mask, and the second conductive layer 5 is etched through the mask to form a second opening 6 penetrating the second conductive layer 5.

[0075] S105: Referring to Figure 3e, a second substrate 9 is formed.

[0076] S106: Referring to FIG3f, a second bonding layer 82 is formed on the second substrate 9;

[0077] In this step, a second bonding layer 82 is formed on the surface of the second substrate 9, for example, by deposition and etching.

[0078] S107: Referring to FIG3g, a groove 11 is formed on the second substrate 9;

[0079] In this step, a resist layer is formed on the bottom surface of the second substrate 9, the resist layer is patterned using a photolithography process to form a mask, and the second substrate 9 is etched through the mask to form a groove 11.

[0080] S108: Referring to FIG3h, the first bonding layer 81 and the second bonding layer 82 are bonded at high temperature to form a bonding structure 8. The second substrate 9 and the first substrate 1 enclose a sealed space. The sealed space includes a plurality of phase-separated chambers 14, each chamber 14 corresponding to a groove 11.

[0081] S109: Referring to FIG3i, an exhaust channel 12 is formed in the second substrate 9 and the bonding structure 8 to release air from at least one of the chambers 14. In the embodiments provided in this application, the sealed space includes a first chamber 141 and a second chamber 142, and the exhaust channel 12 is used to release air from the first chamber 141.

[0082] S110: Continuing to refer to FIG3i, a sealing portion 13 is deposited on the second substrate 9 to seal the exhaust channel 12;

[0083] In this step, the material of the sealing part 13 can be a dielectric or conductive material, so that each chamber 14 is restored to a sealed cavity, improving the working stability.

[0084] S111: Referring to Figure 3j, shape the finished product.

[0085] The above description, based on the embodiments shown in the figures, details the structure, features, and effects of the present invention. The above description is only a preferred embodiment of the present invention, but the present invention is not limited to the scope of implementation shown in the figures. Any changes made in accordance with the concept of the present invention, or equivalent embodiments modified to have equivalent changes, that do not exceed the spirit covered by the specification and figures, should be within the protection scope of the present invention.

Claims

1. An inertial measurement unit, characterized in that, include: First substrate; A dielectric layer is stacked on the first substrate, and a notch is formed on the dielectric layer; A first conductive layer is stacked on the dielectric layer, and the first conductive layer has a plurality of first openings. A second conductive layer is supported on the first conductive layer by a support portion, and the second conductive layer has a plurality of second openings. The second substrate is bonded to the second conductive layer by a bonding structure, and a sealed space is formed between the second substrate and the first substrate. The sealed space includes multiple phase-separated chambers, and the chamber pressures of each chamber are different. An exhaust passage is provided, connecting to at least one of the chambers, the exhaust passage being used to connect the chambers to the outside; A sealing section is used to seal off the exhaust passage.

2. The inertial measurement unit according to claim 1, characterized in that, The exhaust passage includes a first passage section and a second passage section. One end of the first passage section is connected to the outside, and the other end of the first passage section is connected to one end of the second passage section. The other end of the second passage section is connected to the corresponding chamber.

3. The inertial measurement unit according to claim 2, characterized in that, The second channel segment includes multiple sequentially connected exhaust sub-channels.

4. The inertial measurement unit according to claim 2, characterized in that, The first channel segment intersects the second channel segment perpendicularly.

5. The inertial measurement unit according to claim 1, characterized in that, The number of chambers is set to n, where n≥2, and the number of chambers connected to the exhaust channel is n-1 or n.

6. The inertial measurement unit according to claim 1, characterized in that, The sealed space includes a first chamber and a second chamber separated by phase. The pressure in the first chamber is greater than the pressure in the second chamber. The exhaust channel is formed in the second substrate and the bonding structure. One end of the exhaust channel forms a first opening on the outer wall of the second substrate, and the other end of the exhaust channel forms a second opening on the inner wall of the bonding structure. The exhaust channel communicates with the first chamber through the second opening.

7. The inertial measurement unit according to claim 6, characterized in that, The first opening is formed on the top surface of the second substrate, and the closure covers the top surface of the second substrate to close the first opening.

8. The inertial measurement unit according to claim 1, characterized in that, The bonding structure includes a first bonding layer and a second bonding layer bonded together, wherein the first bonding layer is stacked on top of the second conductive layer and the second bonding layer is stacked on the bottom of the second substrate.

9. The inertial measurement unit according to claim 1, characterized in that, The bottom surface of the second substrate is provided with a plurality of connecting blocks, which are connected to the bonding structure, and grooves are formed between adjacent connecting blocks.

10. A method for preparing an inertial measurement unit, used to prepare the inertial measurement unit according to any one of claims 1-9, characterized in that, The inertial measurement unit includes: First substrate; A dielectric layer is stacked on the first substrate, and a notch is formed on the dielectric layer; A first conductive layer is stacked on the dielectric layer, and the first conductive layer has a plurality of first openings. A second conductive layer is supported on the first conductive layer by a support portion, and the second conductive layer has a plurality of second openings. The second substrate is bonded to the second conductive layer by a bonding structure, and a sealed space is formed between the second substrate and the first substrate. The sealed space includes multiple phase-separated chambers, and the chamber pressures of each chamber are different. An exhaust passage is provided, connecting to at least one of the chambers, the exhaust passage being used to connect the chambers to the outside; A sealing section is used to seal off the exhaust passage; The preparation method includes the following steps: Forming the first substrate; The dielectric layer and the first conductive layer are formed on the first substrate, the notch is formed on the dielectric layer, and the first opening is formed on the first conductive layer; A second conductive layer is formed on the first conductive layer, and a first bonding layer is formed on the second conductive layer; The second opening and the support portion are formed on the second conductive layer; Forming a second substrate; A second bonding layer is formed on the second substrate; A groove is formed on the second substrate; The first bonding layer and the second bonding layer are bonded together at high temperature to form a bonding structure. The second substrate and the first substrate enclose a sealed space, which includes multiple phase-separated chambers. An exhaust channel is formed within the second substrate and the bonding structure to release air from at least one of the chambers; A sealing portion is deposited on the second substrate to seal the exhaust channel; Finished product forming.

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