Inertial measurement unit and preparation method thereof

Abstract

The invention discloses an inertial measurement unit and a preparation method thereof. The inertial measurement unit comprises a first substrate; the dielectric layer is stacked on the first substrate, and a notch is formed in the dielectric layer; the first conductive layer is laminated on the dielectric layer; the second conducting layer is supported on the first conducting layer through a supporting part; the second substrate covers the second conductive layer through a bonding structure, a closed space is formed between the second substrate and the first substrate, a plurality of separated cavities are formed in the closed space, and the cavity pressures of the cavities are different; the exhaust channel is communicated to at least one cavity, and the exhaust channel is used for communicating the cavity with the outside; and a closing part. Compared with the prior art, a plurality of cavities with different cavity pressures are obtained on a single wafer, which is beneficial to the manufacturing of the inertial measurement unit in which two or more inertial sensors are assembled together.

Description

Technical Field

[0001] The present invention relates to the technical field of micro-electromechanical systems, and in particular to an inertial measurement unit and a preparation method thereof. Background Art

[0002] Using two or more inertial sensors with different cavity pressures on a single component module is usually called an inertial measurement unit (IMU). The inertial measurement unit can measure acceleration and angular velocity in a single component module.

[0003] Traditionally, inertial measurement units are made of separate inertial sensor chips for different pressures that are manufactured separately on different wafers and then put together as a single component.

[0004] This method doubles the manufacturing materials and manufacturing cycle required to manufacture a single inertial measurement unit with two inertial sensors with different cavity pressures, and the cost and resources are further increased when multiple inertial sensors with different cavity pressures need to be assembled in a single inertial measurement unit. Summary of the invention

[0005] The object of the present invention is to provide an inertial sensor and a method for manufacturing the same to solve the technical problems in the prior art, and it can manufacture two or more inertial sensors with different cavity pressures on a single wafer.

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

[0007] a first substrate;

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

[0009] A first conductive layer, the 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, the second conductive layer being supported on the first conductive layer by a supporting portion, and having a plurality of second openings;

[0011] A second substrate, wherein the second substrate is covered on the second conductive layer through a bonding structure, and a closed space is formed between the second substrate and the first substrate, wherein the closed space includes a plurality of separated chambers, and the chamber pressures of the chambers are different;

[0012] an exhaust passage connected to at least one of the chambers, the exhaust passage being used to connect the chamber with the outside;

[0013] The closing portion is used to close the exhaust passage.

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

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

[0016] In the inertial measurement unit as described above, preferably, the first channel section intersects the second channel section perpendicularly.

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

[0018] In the inertial measurement unit as described above, preferably, the enclosed space includes a first chamber and a second chamber separated from each other, the chamber pressure of the first chamber is greater than the chamber 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 is connected to the first chamber via the second opening.

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

[0020] In the inertial measurement unit as described above, preferably, the bonding structure includes a first bonding layer and a second bonding layer which are bonded to each other, 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.

[0021] In the inertial measurement unit as described above, preferably, a plurality of connection blocks are protruding from the bottom surface of the second substrate, the connection blocks are connected to the bonding structure, and grooves are formed between adjacent connection blocks.

[0022] In a second aspect, the present invention provides a method for preparing an inertial measurement unit, which is used for the aforementioned inertial measurement unit, and the inertial measurement unit comprises:

[0023] a first substrate;

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

[0025] A first conductive layer, the 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, the second conductive layer being supported on the first conductive layer by a supporting portion, and having a plurality of second openings;

[0027] A second substrate, wherein the second substrate is covered on the second conductive layer through a bonding structure, and a closed space is formed between the second substrate and the first substrate, wherein the closed space includes a plurality of separated chambers, and the chamber pressures of the chambers are different;

[0028] an exhaust passage connected to at least one of the chambers, the exhaust passage being used to connect the chamber with the outside;

[0029] A closing portion, used for closing the exhaust passage;

[0030] The preparation method comprises the following steps:

[0031] forming a first substrate;

[0032] forming the dielectric layer and the first conductive layer on the first substrate, forming the notch on the dielectric layer, and forming the first opening on the first conductive layer;

[0033] forming a second conductive layer on the first conductive layer, and forming a first bonding layer on the second conductive layer;

[0034] forming the second opening and the supporting portion on the second conductive layer;

[0035] forming a second substrate;

[0036] forming a second bonding layer on the second substrate;

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

[0038] Bonding the first bonding layer and the second bonding layer at high temperature to form a bonding structure, wherein the second substrate and the first substrate are enclosed to form a closed space, wherein the closed space includes a plurality of separated chambers;

[0039] forming an exhaust channel in the second substrate and the bonding structure to release air from at least one of the chambers;

[0040] Depositing a sealing portion on the second substrate to seal the exhaust channel;

[0041] The finished product is formed.

[0042] Compared with the prior art, the present invention provides at least one exhaust channel connected to at least one chamber so that air can be drawn out of the exhaust channel and escape from the chamber, and then uses a sealing portion to seal the exhaust channel, thereby achieving multiple chambers with different chamber pressures on a single wafer, which is helpful for the manufacture of an inertial measurement unit that assembles two or more inertial sensors together, thereby allowing the inertial measurement unit to be differentiated according to the different required functions and performance specifications. Since the materials and manufacturing processes of the inertial sensors are similar, this method reduces the manufacturing cycle time, materials and costs of each unit of the inertial measurement unit. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0044] Figure 2a-2c yes Figure 1 AA section diagram (exhaust channels with various structures);

[0045] Figure 3a-3j It is a flow chart of the preparation of the inertial sensor according to the embodiment of the present invention.

[0046] Explanation of the figure numbers: 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 section, 122-second channel section, 123-exhaust sub-channel, 13-closing portion, 14-chamber, 141-first chamber, 142-second chamber, 15-notch. DETAILED DESCRIPTION

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

[0048] like Figure 1 As shown, an embodiment of the present invention provides an inertial sensor, which includes, from bottom to top, 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 a feasible implementation, the first substrate 1 is circular. Those skilled in the art will appreciate that the first substrate 1 may also be in other shapes, such as a square, etc., which is not limited here.

[0050] The dielectric layer 2 is stacked on the 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 realize electrical isolation between the first conductive layer 3 and the first substrate 1. A gap 15 is formed on the dielectric layer 2. In a feasible implementation manner, 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 conductive material, such as polysilicon.

[0052] The second conductive layer 5 is supported on the first conductive layer 3 by a supporting portion 7. The supporting 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 made of a conductive material, such as polysilicon.

[0053] The second substrate 9 is covered on the second conductive layer 5 through a bonding structure 8. The bonding structure 8 includes a first bonding layer 81 and a second bonding layer 82 that are bonded to each other. The first bonding layer 81 is stacked on the top of the first conductive layer 3, and the second bonding layer 82 is stacked on the bottom of the second conductive layer 5. The first bonding layer 81 and the second bonding layer 82 are both made of metal to form metal hot pressing bonding.

[0054] The second substrate 9 is a semiconductor substrate, such as a silicon substrate. In a feasible implementation, the second substrate 9 is circular. Those skilled in the art will appreciate that the second substrate 9 may also be in other shapes, such as a square, etc., which are not limited here. The second substrate 9 and the first substrate 1 form a closed space, so that the internal structure of the inertial sensor is protected from interference from the external environment, making it easier to control the air pressure in the cavity and improving working stability.

[0055] The enclosed space includes a plurality of separated chambers 14, and the chamber pressures of the chambers 14 are different. The number of the chambers 14 is at least two. The number of the chambers 14 and the chamber pressures of the chambers 14 can be determined according to actual needs and are not limited here. In the embodiment provided in the present application, an exhaust channel 12 is provided, and the exhaust channel 12 can be set on any wall of the chamber 14. One end of the exhaust channel 12 is connected to the interior of the chamber 14, and the other end of the exhaust channel 12 is connected to the outside. In the embodiment provided in the present 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, the exhaust channel 12 can be set in only one chamber 14, and the corresponding chamber 14 can be exhausted by using the exhaust channel 12, so that the air is drawn out from the exhaust channel 12 and escapes from the chamber 14, while the initial chamber pressure is maintained in the other chamber 14, so that multiple chambers 14 with different chamber pressures can be obtained on a single wafer. Alternatively, the 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 pressure, and the chamber pressures in the two chambers 14 are also different.

[0057] The number of exhaust channels 12 possessed by each chamber 14 connected to the exhaust channel 12 may be one or more, which is not limited herein. In the case of having multiple exhaust channels 12, the exhaust speed of the air in the chamber 14 is faster, but it may also cause undesirable consequences such as a more complicated structure and poor sealing stability. In the embodiments provided in the present application, the number of exhaust channels 12 possessed by each chamber 14 connected to the exhaust channel 12 is one.

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

[0059] In the embodiment provided in the present application, in order to prevent the deposition material used for sealing from being deposited into the exhaust channel 12 through the exhaust channel 12 when the sealing portion 13 seals the exhaust channel 12, the exhaust channel 12 includes a first channel section 121 and a second channel section 122, one end of the first channel section 121 is connected to the outside, the other end of the first channel section 121 is connected to one end of the second channel section 122, and the other end of the second channel section 122 is connected to the corresponding chamber 14. When the sealing portion 13 seals the exhaust channel 12, the deposition material of the sealing portion 13 flows along the first channel section 121. Since the extension directions of the first channel section 121 and the second channel section 122 are not parallel, the deposition material of the sealing portion 13 will hinder the flow of the material at the turning point to prevent the deposition material of the sealing portion 13 from flowing into the chamber 14.

[0060] Furthermore, the second channel section 122 includes a plurality of exhaust sub-channels 123 connected in sequence, and the plurality of exhaust sub-channels 123 are located in the same plane, so that a plurality of turns can be formed at adjacent exhaust sub-channels 123, which can more effectively hinder the flow of the deposition material in the closed portion 13 and prevent the deposition material from being deposited in the chamber 14 and affecting the performance of the device.

[0061] Figure 2a-2cThe structures and numbers of the multiple exhaust sub-channels 123 in the second channel section 122 are exemplified. Those skilled in the art will appreciate that the number and shape of the exhaust sub-channels 123 may be determined based on actual needs and are not limited here.

[0062] In a feasible implementation, the first channel section 121 intersects the second channel section 122 at right angles, and when the deposition material in the closed portion 13 flows to the bend, it abuts against the wall at the bend. Since the two adjacent walls intersect at right angles, the walls do not give the deposition material a friction force to continue flowing, and the deposition material is easy to accumulate at the bend, which has a better blocking effect on the deposition material.

[0063] In the embodiments provided in this application, refer to Figure 1 , Figure 2a to Figure 2c As shown, there are two separated chambers 14 in the enclosed space, namely the first chamber 141 and the second chamber 142. The first chamber 141 is a high-pressure chamber, and the second chamber 142 is a low-pressure chamber. The pressure of the first chamber 141 is greater than the pressure of the second chamber 142. The exhaust channel 12 is formed in the second substrate 9 and the bonding structure 8. In a feasible implementation, the main part of the first channel section 121 is located in the second substrate 9, the second channel section 122 is located in the bonding structure 8, and the connection between the first channel section 121 and the second channel section 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, and the first opening is formed at the end of the first channel section 121. The other end of the exhaust channel 12 forms a second opening on the inner wall surface of the bonding structure 8, and the second opening is formed at the end of the second channel section 122. The exhaust channel 12 is connected to the first chamber 141 via the second opening.

[0064] Furthermore, the first channel section 121 extends along the height direction of the inertial measurement unit, and the second channel section 122 extends along the horizontal direction. The first channel section 121 intersects the second channel section 122 vertically. The first opening is formed on the top surface of the second substrate 9, which is conducive to the deposition and forming of the closing portion 13. The closing portion 13 covers the top surface of the second substrate 9 to close the first opening. The closing portion 13 is a film structure formed by the deposition of dielectric or conductive materials. After the cavity pressure of the first chamber 141 reaches the preset requirements, a layer of dielectric or conductive material is deposited on the top surface of the second substrate 9, so that each chamber 14 is restored to a closed cavity to improve working stability.

[0065] In a feasible implementation mode, referring to Figure 1As shown, the support portion 7 includes a plurality of support blocks 71, the bottom end of the support block 71 is connected to the first conductive layer 3, 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, and 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, so that the capacitance signal in the corresponding direction can be detected to realize the detection of inertia.

[0066] In the embodiment provided in the present application, a plurality of connection blocks 10 are protruding from the bottom surface of the second substrate 9, and the connection blocks 10 are connected to the bonding structure 8. Grooves 11 are formed between adjacent connection blocks 10, and each chamber 14 corresponds to a groove 11 to provide space for the second conductive layer 5 to shift.

[0067] Based on the above embodiments, refer to Figure 3a-3c As shown, the present invention also provides a method for preparing an inertial sensor, the preparation method comprising the following steps:

[0068] S101: Reference Figure 3a As shown, a first substrate 1 is formed.

[0069] S102: Reference Figure 3b As shown, 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 deposited on the surface of the first conductive layer 3, the resist layer is patterned by a photolithography process 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: Reference Figure 3c As shown, 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 by, for example, deposition and etching.

[0073] S104: Reference Figure 3d As shown, a second opening 6 and a supporting 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 by 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: Reference Figure 3e As shown, a second substrate 9 is formed.

[0076] S106: Reference Figure 3f As shown, 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 by, for example, deposition and etching.

[0078] S107: Reference Figure 3g As shown, 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 by a photolithography process to form a mask, and the second substrate 9 is etched through the mask to form a groove 11 .

[0080] S108: Reference Figure 3h As shown, the first bonding layer 81 and the second bonding layer 82 are bonded at high temperature to form a bonding structure 8, and the second substrate 9 and the first substrate 1 are enclosed to form a closed space, which includes a plurality of separated chambers 14, each chamber 14 corresponds to a groove 11.

[0081] S109: Reference Figure 3i As shown, an exhaust channel 12 is formed in the second substrate 9 and the bonding structure 8 to release the air in at least one of the chambers 14. In the embodiment provided in the present application, the enclosed space includes a first chamber 141 and a second chamber 142, and the exhaust channel 12 is used to release the air in the first chamber 141.

[0082] S110: Continue to refer to Figure 3i As shown, a closing portion 13 is deposited on the second substrate 9 to close the exhaust channel 12;

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

[0084] S111: Reference Figure 3j As shown, the finished product is formed.

[0085] The above describes in detail the structure, features and effects of the present invention based on the embodiments shown in the drawings. The above is only a preferred embodiment of the present invention, but the present invention is not limited to the scope of implementation shown in the drawings. Any changes made according to the concept of the present invention, or modifications to equivalent embodiments with equivalent changes, which still do not exceed the spirit covered by the description and drawings, should be within the protection scope of the present invention.

Claims

1. An inertial measurement unit, characterized in that: include: a first substrate; a dielectric layer, the dielectric layer being stacked on the first substrate and having a notch formed on the dielectric layer; A first conductive layer, the first conductive layer is stacked on the dielectric layer, and the first conductive layer has a plurality of first openings; a second conductive layer, the second conductive layer being supported on the first conductive layer by a supporting portion, and having a plurality of second openings; A second substrate, wherein the second substrate is covered on the second conductive layer through a bonding structure, and a closed space is formed between the second substrate and the first substrate, wherein the closed space includes a plurality of separated chambers, and the chamber pressures of the chambers are different; an exhaust passage connected to at least one of the chambers, the exhaust passage being used to connect the chamber with the outside; The closing portion is used to close the exhaust passage.

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

3. The inertial measurement unit according to claim 2, characterized in that: The second channel section includes a plurality of exhaust sub-channels connected in sequence.

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

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

6. The inertial measurement unit according to claim 1, characterized in that: The enclosed space includes a first chamber and a second chamber separated from each other, the chamber pressure of the first chamber is greater than the chamber 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, and the other end of the exhaust channel forms a second opening on the inner wall surface of the bonding structure, and the exhaust channel is connected to the first chamber via 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 closing portion 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 which are bonded to each other. 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: A plurality of connection blocks are convexly disposed on the bottom surface of the second substrate. The connection blocks are connected to the bonding structure, and grooves are formed between adjacent connection blocks.

10. A method for preparing an inertial measurement unit, used for preparing the inertial measurement unit according to any one of claims 1 to 9, characterized in that: The inertial measurement unit comprises: a first substrate; a dielectric layer, the dielectric layer being stacked on the first substrate and having a notch formed on the dielectric layer; A first conductive layer, the first conductive layer is stacked on the dielectric layer, and the first conductive layer has a plurality of first openings; a second conductive layer, the second conductive layer being supported on the first conductive layer by a supporting portion, and having a plurality of second openings; A second substrate, wherein the second substrate is covered on the second conductive layer through a bonding structure, and a closed space is formed between the second substrate and the first substrate, wherein the closed space includes a plurality of separated chambers, and the chamber pressures of the chambers are different; an exhaust passage connected to at least one of the chambers, the exhaust passage being used to connect the chamber with the outside; A closing portion, used for closing the exhaust passage; The preparation method comprises the following steps: forming a first substrate; forming the dielectric layer and the first conductive layer on the first substrate, forming the notch on the dielectric layer, and forming the first opening on the first conductive layer; forming a second conductive layer on the first conductive layer, and forming a first bonding layer on the second conductive layer; forming the second opening and the supporting portion on the second conductive layer; forming a second substrate; forming a second bonding layer on the second substrate; A groove is formed on the second substrate; Bonding the first bonding layer and the second bonding layer at high temperature to form a bonding structure, wherein the second substrate and the first substrate are enclosed to form a closed space, wherein the closed space includes a plurality of separated chambers; forming an exhaust channel in the second substrate and the bonding structure to release air from at least one of the chambers; Depositing a sealing portion on the second substrate to seal the exhaust channel; The finished product is formed.

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