MEMS heat dissipation device, preparation method thereof and electronic equipment

Abstract

A MEMS heat dissipation device, a preparation method thereof and an electronic device, the MEMS heat dissipation device comprising: a first cover plate structure and a functional layer, the first cover plate structure and the functional layer enclosing a first cavity, the first cover plate structure being provided with a first air vent communicating with the first cavity; a second cover plate structure located on a side of the functional layer away from the first cover plate structure and enclosing a second cavity with the functional layer; the second cover plate structure being provided with a second air vent communicating with the second cavity; the functional layer comprising: a fan blade, a rotating shaft fixedly connected with the fan blade, and an electrostatic driving assembly, the rotating shaft extending along a first direction and being connected with the first cover plate structure, the electrostatic driving assembly comprising: fixed electrodes located on opposite sides of the rotating shaft along a second direction, and movable electrodes located on the opposite sides of the rotating shaft along the second direction, the movable electrodes being fixedly connected with the rotating shaft; the fixed electrodes on the two sides of the rotating shaft being configured to drive the movable electrodes and the fan blade to periodically twist around the rotating shaft.

Description

Technical Field

[0001] This disclosure belongs to the field of heat dissipation technology for electronic devices, specifically relating to a MEMS heat dissipation device and its fabrication method, and electronic equipment. Background Technology

[0002] As global electronic devices continue to rapidly develop towards miniaturization, high performance, and high integration, cooling and heat dissipation have become a major bottleneck restricting the improvement of device performance and affecting reliability.

[0003] Existing thermal management technologies are mainly divided into two categories: passive heat dissipation and active heat dissipation. Although passive heat dissipation solutions such as heat sinks and heat pipes have long dominated, they are often unable to meet the needs independently as the heat flux density of new-generation electronic devices (such as wearable devices and edge AI devices) continues to increase. Traditional active heat dissipation solutions such as mechanical fans and liquid cooling (with dimensions in the centimeter and decimeter range) are relatively mature, but they are gradually showing limitations in space-constrained and power-sensitive application scenarios, specifically: (1) traditional mechanical fans are large in size and consume a lot of energy; (2) liquid cooling systems have complex structures, occupy a large area, and are prone to leakage. Therefore, there is an urgent need to develop miniaturized and low-power active heat dissipation solutions. Summary of the Invention

[0004] This disclosure provides a MEMS heat dissipation device, including:

[0005] A first cover plate structure and a functional layer are stacked together, the first cover plate structure and the functional layer form a first chamber, and the first cover plate structure has a first vent that communicates with the first chamber.

[0006] The second cover plate structure is located on the side of the functional layer away from the first cover plate structure, and together with the functional layer, forms a second chamber; the second cover plate structure is provided with a second vent that communicates with the second chamber.

[0007] The functional layer includes: fan blades, a rotating shaft fixedly connected to the fan blades, and an electrostatic drive assembly. The rotating shaft extends along a first direction and is connected to the first cover plate structure. The electrostatic drive assembly includes: fixed electrodes located on opposite sides of the rotating shaft along a second direction, and movable electrodes located on opposite sides of the rotating shaft along the second direction. The movable electrodes are fixedly connected to the rotating shaft and spaced apart from the fixed electrodes. The second direction intersects the first direction.

[0008] The fixed electrodes on both sides of the rotating shaft are configured to drive the movable electrode and the fan blade to rotate periodically around the rotating shaft.

[0009] In some embodiments, the fixed electrode includes a plurality of first comb teeth arranged along the first direction and extending along the second direction, and the movable electrode includes a plurality of second comb teeth arranged along the first direction and extending along the second direction. On the same side of the rotating shaft, the first comb teeth and the second comb teeth are alternately arranged in the first direction.

[0010] In some embodiments, the lengths of both the first comb tooth portion and the second comb tooth portion are between 2 micrometers and 100 micrometers;

[0011] And / or, the spacing between the first comb teeth and the second comb teeth arranged along the first direction is between 0.1 micrometers and 5 micrometers.

[0012] In some embodiments, the first cover plate structure includes: a support frame and a first cover plate fixedly connected, wherein the first cover plate is located on the side of the support frame away from the functional layer, and the first vent penetrates the first cover plate.

[0013] The MEMS heat dissipation device further includes:

[0014] The first pad is fixed on the support frame and electrically connected to the fixed electrode through the support frame, and is used to provide an AC signal to the fixed electrode.

[0015] The second pad is fixed on the support frame and electrically connected to the movable electrode through the support frame, and is used to provide a fixed voltage signal to the movable electrode; the first pad and the second pad are insulated from each other.

[0016] In some embodiments, the first cover plate structure further includes an insulating layer, wherein the insulating layer has a first interconnection hole and a second interconnection hole.

[0017] The functional layer further includes: a first connecting portion and a second connecting portion with an insulating gap, the first connecting portion being electrically connected to the fixed electrode and electrically connected to the support frame through the first interconnecting hole; the second connecting portion being electrically connected to the movable electrode through the rotating shaft and electrically connected to the support frame through the second interconnecting hole.

[0018] In some embodiments, the support frame is provided with a plurality of isolation slots, which divide the support frame into a plurality of first frame portions and at least one second frame portion. The first pad is electrically connected to the first frame portion, and the second pad is electrically connected to the second frame portion. The first connecting portion is electrically connected to the first frame portion through the first interconnecting hole, and the second connecting portion is electrically connected to the second frame portion through the second interconnecting hole.

[0019] In some embodiments, the number of second vents is multiple, the orthographic projection area of ​​the first vent on the reference plane is greater than the sum of the orthographic projection areas of the multiple second vents on the reference plane; and / or, the distance from the functional layer to the second vent is less than the distance from the functional layer to the first vent.

[0020] In some embodiments, the size of the first vent in the first direction is 0.8 to 1.2 times the size of the fan blade in the first direction, and the size of the first vent in the second direction is greater than the size of the fan blade in the second direction.

[0021] In some embodiments, the orthographic projection of the extension line of the shaft axis onto the reference plane is located outside the orthographic projection of the second vent onto the reference plane, and the reference plane is a plane perpendicular to the arrangement direction of the first cover structure and the second cover structure.

[0022] In some embodiments, the size of the second vent in the first direction is 0.8 to 1.2 times the size of the fan blade in the first direction.

[0023] In some embodiments, the functional layer includes at least two fan blades arranged along the second direction, each fan blade being fixedly connected to a corresponding rotating shaft, and a fixed electrode being disposed between the rotating shafts connected to adjacent two fan blades; the adjacent two fan blades have a spacing of 5 micrometers to 50 micrometers in the untwisted state.

[0024] In some embodiments, the fan blades, the shaft, and the electrostatic drive assembly are made of the same material.

[0025] This disclosure also provides a method for fabricating a MEMS heat dissipation device, including:

[0026] Forming a second cover plate structure;

[0027] A first cover plate structure and a functional layer are formed and stacked sequentially. A second cover plate structure is bonded to the side of the functional layer away from the first cover plate structure. The second cover plate structure and the functional layer form a second chamber. A second vent is provided on the second cover plate structure to communicate with the second chamber. The first cover plate structure and the functional layer form a first chamber. A first vent is provided on the first cover structure to communicate with the first chamber.

[0028] The functional layer includes: fan blades, a rotating shaft fixedly connected to the fan blades, and an electrostatic drive assembly. The rotating shaft extends along a first direction and is connected to the first cover plate structure. The electrostatic drive assembly includes: fixed electrodes located on opposite sides of the rotating shaft along a second direction, and movable electrodes located on opposite sides of the rotating shaft along the second direction. The movable electrodes are fixedly connected to the rotating shaft and spaced apart from the fixed electrodes. The second direction intersects the first direction.

[0029] The fixed electrodes on both sides of the rotating shaft are configured to drive the movable electrode and the fan blade to rotate periodically around the rotating shaft.

[0030] In some embodiments, the first cover structure includes a support frame and a first cover;

[0031] The steps for forming the first cover plate structure and functional layer stacked sequentially include:

[0032] Provide a frame material layer;

[0033] An insulating layer is formed on one side of the frame material layer, and a first interconnection hole and a second interconnection hole are formed on the insulating layer;

[0034] The functional layer is formed, and the functional layer further includes a first connecting portion and a second connecting portion, wherein the first connecting portion is electrically connected to the fixed electrode and the second connecting portion is electrically connected to the movable electrode;

[0035] The second cover plate structure is bonded to the side of the functional layer away from the frame material layer;

[0036] The frame material layer is patterned to form a support frame, the support frame including a plurality of first frame portions and at least one second frame portion that are insulated from each other, wherein the first connecting portion is electrically connected to the first frame portion through the first interconnecting hole, and the second frame portion is electrically connected to the frame material layer through the second interconnecting hole;

[0037] The second cover plate is fixed to the side of the support frame away from the functional layer.

[0038] This disclosure also provides an electronic device, including a heat-dissipating element and the above-described MEMS heat dissipation device, wherein the first cover structure is located on the side of the second cover structure away from the heat-dissipating element. Attached Figure Description

[0039] Figure 1 This is a top view of a MEMS heat dissipation device provided in some embodiments of this disclosure.

[0040] Figure 2This is a bottom view of the MEMS heat dissipation device provided in the embodiments of this disclosure.

[0041] Figure 3 for Figure 1 Top view of the first cover plate.

[0042] Figure 4 for Figure 1 A top view of the supporting frame.

[0043] Figure 5 for Figure 1 A schematic diagram of the functional layers in the diagram.

[0044] Figure 6 for Figure 1 A top view of the second cover plate structure.

[0045] Figure 7 For along Figure 1 A cross-sectional view of line A-A' in the middle.

[0046] Figure 8 For along Figure 1 A cross-sectional view of line B-B' in the middle.

[0047] Figure 9 This is a schematic diagram illustrating the working process of the MEMS heat dissipation structure provided in the embodiments of this disclosure.

[0048] Figure 10 This is a cross-sectional view of a MEMS heat dissipation device provided in some other embodiments of this disclosure.

[0049] Figure 11 for Figure 10 A schematic diagram of airflow during heat dissipation in a MEMS heat dissipation device.

[0050] Figures 12A to 12M This is a schematic diagram illustrating the specific fabrication process of a MEMS heat dissipation device provided in one example of this disclosure.

[0051] Figure 13 A schematic diagram showing the formation of a second vent during the fabrication process of a MEMS heat dissipation device, which is provided as another example of this disclosure. Detailed Implementation

[0052] To enable those skilled in the art to better understand the technical solutions of this disclosure, the disclosure will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0053] Unless otherwise defined, the technical or scientific terms used in this disclosure shall have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms “a,” “an,” “an,” “the,” and similar words used in this disclosure do not indicate quantity limitation and may indicate singular or plural. The terms “comprising,” “including,” “having,” and any variations thereof used in this disclosure are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or device that includes a series of steps or modules (units) is not limited to the listed steps or units, but may also include steps or units not listed, or may include other steps or units inherent to such processes, methods, products, or devices. The terms “connected,” “linked,” “coupled,” and similar words used in this disclosure are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. “Multiple” in this disclosure refers to two or more. “And / or” describes the relationship between related objects, indicating that three relationships may exist; for example, “A and / or B” can indicate: A alone, A and B simultaneously, or B alone. The character " / " generally indicates that the preceding and following objects are in an "or" relationship. The terms "first," "second," "third," etc., used in this disclosure are merely to distinguish similar objects and do not represent a specific ordering of objects. "Above," "below," "left," "right," etc., are only used to indicate relative positional relationships; when the absolute position of the described objects changes, the relative positional relationship may also change accordingly.

[0054] This document describes exemplary embodiments with reference to sectional views and / or plan views, which are idealized exemplary drawings. In the drawings, the thickness of layers and regions is enlarged for clarity. Therefore, variations in shape relative to the drawings are contemplated due to, for example, manufacturing techniques and / or tolerances. Therefore, exemplary embodiments should not be construed as limited to the shapes of the regions shown herein, but rather include shape deviations due to, for example, manufacturing processes. Thus, the regions shown in the drawings are schematic in nature, and their shapes are not intended to show the actual shapes of the regions of the device, nor are they intended to limit the scope of the exemplary embodiments.

[0055] Microelectromechanical systems (MEMS) fans are a novel heat dissipation solution. They are miniature active cooling devices manufactured using MEMS technology, achieving airflow control through micrometer-level structures. They feature ultra-small size, low power consumption, and quiet operation, primarily addressing the problem of localized high heat loads in modern electronic devices. However, current common MEMS fans mainly use piezoelectric film layers to fabricate airflow-driving beams. This approach suffers from relatively high power consumption, poor compatibility with standard semiconductor processes, and high manufacturing costs.

[0056] Figure 1This is a top view of a MEMS heat dissipation device provided in some embodiments of this disclosure. Figure 2 This is a bottom view of the MEMS heat dissipation device provided in the embodiments of this disclosure. Figure 3 for Figure 1 Top view of the first cover plate in the middle. Figure 4 for Figure 1 Top view of the supporting frame in the middle. Figure 5 for Figure 1 A schematic diagram of the functional layers in the diagram. Figure 6 for Figure 1 A top view of the second cover plate structure in the middle. Figure 7 For along Figure 1 A sectional view of line A-A' in the middle. Figure 8 For along Figure 1 A sectional view of line B-B' in the middle. Figure 9 This is a schematic diagram illustrating the working process of the MEMS heat dissipation structure provided in the embodiments of this disclosure.

[0057] like Figure 1 , Figure 7 and Figure 8 As shown, the MEMS heat dissipation device includes: a first cover plate structure 10 and a functional layer 30 stacked together, and a second cover plate structure 20. The first cover plate structure 10 and the functional layer 30 form a first chamber Sp1. The first cover plate structure 10 has a first vent 11v communicating with the first chamber Sp1. The second cover plate structure 20 is located on the side of the functional layer 30 away from the first cover plate structure 10, and together with the functional layer 30, forms a second chamber Sp2. The second cover plate structure 20 has a second vent 20v communicating with the second chamber Sp2.

[0058] Among them, such as Figure 5 As shown, the functional layer 30 includes: a fan blade 34, a rotating shaft 33 fixedly connected to the fan blade 34, and an electrostatic drive assembly. The rotating shaft 33 extends along a first direction and is connected to the first cover plate structure 10. The electrostatic drive assembly includes: fixed electrodes 31 located on opposite sides of the rotating shaft 33 along a second direction, and movable electrodes 32 located on opposite sides of the rotating shaft 33 along the second direction. The movable electrodes 32 are fixedly connected to the rotating shaft 33 and spaced apart from the fixed electrodes 31. The first direction and the second direction intersect, for example, the first direction and the second direction are perpendicular.

[0059] The fixed electrodes 31 on both sides of the rotating shaft 33 are configured to drive the movable electrode 32 and the fan blade 34 to periodically twist around the rotating shaft 33. Optionally, the movable electrode 32 is used to apply a fixed reference voltage signal, such as a ground voltage signal. Optionally, the fixed electrodes 31 on both sides of the rotating shaft 33 are used to apply alternating current signals of opposite polarity to drive the movable electrode 32 and the fan blade 34 to periodically twist around the rotating shaft 33.

[0060] When a MEMS heat dissipation device is used to dissipate heat from a component to be cooled, one of the first vent 11V and the second vent 20V can be used as an air inlet, and the other as an air outlet, with the outlet facing the component to be cooled. The following explanation uses the second vent 20V as an example to illustrate the heat dissipation process of the MEMS heat dissipation device. Figure 9 As shown, in the initial state (without fan blade 34 twisting), fan blade 34 remains approximately horizontal. When heat dissipation is required for the heat-dissipating component, opposite polarity AC signals are applied to the fixed electrodes 31 on both sides of the shaft 33, while a reference signal is applied to the movable electrode 32. When a positive voltage of the AC signal is applied to one fixed electrode 31 and a negative voltage of the AC signal is applied to the other fixed electrode 31, the two fixed electrodes 31 generate electrostatic forces in opposite directions on the movable electrode 32, forming a torque that drives the fan to swing downwards. When fan blade 34 begins to swing downwards from the initial state, the volume of the second chamber Sp2 is compressed, and the internal air is forced out at high speed, forming a directional air jet that blows directly onto the surface of the component requiring heat dissipation. At the same time, the volume of the first chamber Sp1 increases accordingly, the internal air pressure decreases, and outside air enters the first chamber Sp1. Subsequently, the polarity of the external drive signal reverses, and the fixed electrode 31, which was previously applied with a positive voltage, becomes applied with a negative voltage, while the fixed electrode 31 on the other side, which was previously applied with a negative voltage, is now applied with a positive voltage. The directions of the electrostatic forces on both sides are thus reversed. Under the combined action of the reverse electrostatic torque and its own mechanical elastic restoring force, the fan blade 34 begins to swing upwards, returns, and passes through its equilibrium position, continuing to swing towards the first chamber Sp1. This compresses the volume of the first chamber Sp1, allowing the air inside Sp1 to be smoothly squeezed out through the first vent 11v. Meanwhile, the second chamber Sp2, due to the increased volume and resulting negative pressure, allows air from the side where the heat dissipation element is located to enter the second chamber Sp2 through the second vent 20v. This cycle repeats, circulating the airflow and thus dissipating heat from the heat dissipation element.

[0061] In this embodiment, the functional layer 30 integrates an electrostatic drive assembly, a fan blade 34, and a rotating shaft 33. The electrostatic drive assembly includes fixed electrodes 31 and movable electrodes 32 arranged at intervals. By applying alternating current signals of opposite polarity to the fixed electrodes 31 on both sides of the rotating shaft 33, electrostatic forces of opposite directions are generated, driving the fan blade 34 to periodically twist around the rotating shaft 33, thereby promoting airflow to dissipate heat from the heat dissipation element. Compared with piezoelectric drive, this electrostatic drive method generates less energy loss, resulting in lower drive power consumption; moreover, this electrostatic drive method has lower operating noise.

[0062] In some embodiments, such as Figure 1 , Figure 2 and Figure 5As shown, the fixed electrode 31 includes a plurality of first comb teeth 311 arranged along a first direction and extending along a second direction, and the movable electrode 32 includes a plurality of second comb teeth 321 arranged along the first direction and extending along the second direction. On the same side of the rotating shaft 33, the first comb teeth 311 and the second comb teeth 321 are alternately arranged in the first direction. This comb tooth structure increases the area of ​​the electrostatic field between the fixed electrode 31 and the movable electrode 32, thereby generating a sufficiently large driving torque within a small size, ensuring the effective oscillation of the fan blade 34.

[0063] In some embodiments, such as Figure 5 As shown, the length f1 of the first comb tooth portion 311 and the length f2 of the second comb tooth portion 321 are both between 2 micrometers and 100 micrometers, thereby further increasing the area of ​​the electrostatic field between the fixed electrode 31 and the movable electrode 32. And / or, the distance h between the first comb tooth portion 311 and the second comb tooth portion 321 arranged along the first direction is between 0.1 micrometers and 5 micrometers, thereby increasing the electrostatic force between the fixed electrode 31 and the movable electrode 32.

[0064] In some embodiments, the width g1 of the first comb tooth portion 311 and the width g2 of the second comb tooth portion 321 can both be between 1 micrometer and 20 micrometers. The number of the first comb tooth portion 311 and the second comb tooth portion 321 is not specifically limited.

[0065] In some embodiments, such as Figure 5 As shown, the fan blade 34 is connected to two rotating shafts 33 on both sides along the first direction. The two rotating shafts 33 arranged along the first direction are coaxially arranged to ensure that the fan blade 34 can swing smoothly. In addition, the fan blade 34 has a centerline extending along the first direction, which can be located on the same straight line as the axis of the rotating shaft 33, thereby ensuring that the fan blade 34 is subjected to balanced forces.

[0066] In some embodiments, the dimension b in the first direction and the dimension a in the second direction of the fan blade 34 can both be between 50 micrometers and 2 millimeters. The fan blade 34 can be square, rectangular, polygonal, I-shaped, or other shapes that can realize the fan function.

[0067] In some embodiments, the depth of the second chamber Sp2 can be between 100 micrometers and 500 micrometers to prevent affecting the rotation of the fan blades 34.

[0068] In some embodiments, the dimension d of the rotating shaft 33 in the second direction can be between 2 micrometers and 50 micrometers, and the length e of the rotating shaft 33 can be between 20 micrometers and 500 micrometers. The orthographic projection of the rotating shaft 33 onto the reference plane can be a rectangle, a serpentine shape, an L-shape, or other shapes that allow the fan blades 34 to twist around the axis, and is not limited here. The reference plane is a plane perpendicular to the arrangement direction of the first cover plate structure 10 and the second cover plate structure 20.

[0069] In some embodiments, such as Figure 5 As shown, the functional layer 30 may include a plurality of fan blades 34 arranged along the second direction, each fan blade 34 being connected to a corresponding rotating shaft 33, and different fan blades 34 being connected to different rotating shafts 33. In this embodiment, a MEMS heat dissipation device including two fan blades 34 is used as an example for illustration. Figure 5 As shown, movable electrodes 32 are provided on both sides of the rotating shaft 33 to which each fan blade 34 is connected, and fixed electrodes 31 are provided between the rotating shafts 33 to which two adjacent fan blades 34 are connected. For example, as Figure 5 As shown, movable electrodes 32 are provided on both the left and right sides of the left rotating shaft 33. The movable electrodes 32 include multiple second comb teeth 321. Fixed electrodes 31 are provided on both the left and right sides of the right rotating shaft 33. The fixed electrodes 31 include multiple first comb teeth 311. The multiple second comb teeth 321 on the right side of the left rotating shaft 33 and a portion of the first comb teeth 311 of the middle fixed electrode 31 are alternately arranged in the first direction. The multiple second comb teeth 321 on the left side of the right rotating shaft 33 and another portion of the first comb teeth 311 of the middle fixed electrode 31 are alternately arranged in the first direction.

[0070] For example, the distance c between two adjacent fan blades 34 in the untwisted state is between 5 micrometers and 50 micrometers. The untwisted state refers to the state of being parallel or approximately parallel to the reference plane.

[0071] In some embodiments, such as Figure 3 , Figure 4 and Figure 7 As shown, the first cover plate structure 10 includes a support frame 12 and a cover plate fixedly connected. The cover plate in the first cover plate structure 10 is referred to as the first cover plate 11, and the first cover plate 11 is located on the side of the support frame 12 away from the functional layer 30. A first vent 11v penetrates the first cover plate 11. The material of the support frame 12 may include low-resistivity monocrystalline silicon with a resistivity of less than 0.05 Ω·cm. The first cover plate 11 may be made of glass, such as high borosilicate glass, which facilitates bonding with the support frame 12. The first cover plate 11 may also be made of silicon.

[0072] The orthographic projections of the fan blade 34, the first comb tooth 311, and the second comb tooth 321 on the reference plane do not overlap with the orthographic projection of the support frame 12 on the reference plane, so as to prevent the support frame 12 from obstructing the rotation of the fan blade 34.

[0073] Among them, such as Figure 1 and Figure 8As shown, the MEMS heat dissipation device further includes a first pad 51 and a second pad 52. The first pad 51 is fixed to the support frame 12 and electrically connected to the fixed electrode 31 through the support frame 12, for providing an AC signal to the fixed electrode 31. The second pad 52 is fixed to the support frame 12 and electrically connected to the movable electrode 32 through the support frame 12, for providing a fixed voltage signal to the movable electrode 32; the first pad 51 and the second pad 52 are insulated from each other.

[0074] The first pad 51 can be electrically connected to an external AC power source, thereby transmitting AC signals to the fixed electrode 31. There are multiple first pads 51, with different fixed electrodes 31 connected to different first pads 51. The second pad 52 can be electrically connected to an external DC power source, thereby transmitting a fixed voltage signal to the movable electrode 32.

[0075] In some embodiments, such as Figure 1 and Figure 8 As shown, the first pad 51 and the second pad 52 can be disposed on the surface of the support frame 12 away from the second cover plate structure 20. The orthographic projection of the first cover plate 11 on the reference plane does not overlap with the orthographic projections of the first pad 51 and the second pad 52 on the reference plane, so as to facilitate the connection of the first pad 51 and the second pad 52 to an external power supply. For example, as Figure 3 As shown, the edge of the first cover plate 11 has a clearance notch 11a to avoid the first pad 51 and the second pad 52.

[0076] The first pad 51 and the second pad 52 can be made of metallic materials, such as Au, Al, Cu, Ti, Cr, etc. The first pad 51 and the second pad 52 can be a single-layer metal film or can include multiple metal stacks.

[0077] In some embodiments, combined with Figure 1 , Figure 7 and Figure 8 As shown, the first cover plate structure 10 further includes an insulating layer 40, which has a first interconnection hole V1 and a second interconnection hole V2. For example... Figure 5 As shown, the functional layer 30 also includes: a first connecting part 35 and a second connecting part 36 with an insulating gap. The first connecting part 35 is electrically connected to the fixed electrode 31 and is electrically connected to the support frame 12 through the first interconnection hole V1. The second connecting part 36 is electrically connected to the movable electrode 32 through the rotating shaft 33 and is electrically connected to the support frame 12 through the second interconnection hole V2.

[0078] Among them, combined Figure 4 and Figure 8As shown, the support frame 12 has multiple isolation slots 12v, which divide the support frame 12 into multiple first frame portions 121 and at least one second frame portion 122. A first pad 51 is fixed to and electrically connected to the first frame portion 121, and a second pad 52 is fixed to and electrically connected to the second frame portion 122. The first frame portion 121 can correspond one-to-one with the first connecting portion 35, and the second frame portion 122 can correspond one-to-one with the second connecting portion 36. The first connecting part 35 is electrically connected to the corresponding first frame part 121 through the first interconnecting hole V1, thereby electrically connecting the fixed electrode 31 to the first frame part 121, and thus realizing the electrical connection between the first pad 51 and the fixed electrode 31; the second connecting part 36 is electrically connected to the corresponding second frame part 122 through the second interconnecting hole V2, thereby electrically connecting the movable electrode 32 to the second frame part 122, and thus realizing the electrical connection between the second pad 52 and the movable electrode 32.

[0079] Optionally, a first gap is provided between the first connecting portion 35 and the second connecting portion 36. The width i of the first gap is between 1 and 20 micrometers, and the orthographic projection of the isolation groove 12v on the reference plane overlaps with the orthographic projection of the first gap on the reference plane. The width j of the isolation groove 12v can be equal to or approximately equal to i.

[0080] In some embodiments, there are multiple second vents 20v, and the projected area of ​​the first vent 11v on the reference plane is greater than the sum of the projected areas of the multiple second vents 20v on the reference plane. And / or, the distance from the functional layer 30 to the second vent 20v is less than the distance from the functional layer 30 to the first vent 11v. This arrangement facilitates the timely entry of external air into the first chamber Sp1 and the rapid expulsion of air from the second chamber Sp2 when the fan blade 34 swings downward, forming an air microjet.

[0081] In some embodiments, the dimension of the first vent 11v in the second direction is larger than the dimension of the fan blade 34 in the second direction a, and the dimension of the first vent 11v in the first direction is 0.8 to 1.2 times the dimension of the fan blade 34 in the first direction, so that the dimensions of the first vent 11v and the fan blade 34 in the first direction are approximately equal. In one example, the dimension b of the fan blade 34 in the first direction is between 50 micrometers and 2 millimeters, and the difference in dimension between the first vent 11v and the fan blade 34 in the first direction does not exceed 10 micrometers.

[0082] In some embodiments, the dimension of the second vent 20v in the first direction is 0.8 to 1.2 times the dimension b of the fan blade 34 in the first direction; for example, the difference between the second vent 20v and b does not exceed 10 micrometers. The dimension of the second vent 20v in the second direction can be between 10 micrometers and 50 micrometers. The number of second vents 20v can be one or more; for example, the number of second vents 20v can be multiple, arranged along the second direction, with the interval between two adjacent second vents 20v between 20 micrometers and 200 micrometers. The depth of the second vent 20v can be between 10 micrometers and 100 micrometers to allow other parts within the second chamber Sp2 to be rapidly extruded.

[0083] In one example, such as Figure 7 As shown, each fan blade 34 corresponds to at least two second vents 20v. In the untwisted state, the orthographic projection of each fan blade 34 onto the reference plane overlaps with the orthographic projection of the corresponding plurality of second vents 20v onto the reference plane. The reference plane is a plane perpendicular to the arrangement direction of the first cover plate structure 10 and the second cover plate structure 20.

[0084] In some embodiments, the orthographic projection of the extension line of the axis of the rotating shaft 33 onto the reference plane is outside the orthographic projection of the second vent 20v onto the reference plane. For example, the second vent 20v corresponds to the edge position of the fan blade 34 in the un-twisted state, so that the gas in the second chamber Sp2 can be ejected more quickly when the fan blade 34 is twisted. In some embodiments, the fan blade 34, the rotating shaft 33, and the electrostatic drive assembly in the functional layer 30 are made of the same material, so that the various structures in the functional layer 30 can be fabricated simultaneously in a single patterning process to simplify the manufacturing process. The material of the functional layer may include low-resistivity silicon with a resistivity of less than 0.05 Ω·cm, and may be P-type or N-type, with a thickness between 10 micrometers and 100 micrometers.

[0085] The first comb tooth 311 can be connected to the corresponding first connecting part 35 to form an integral structure, and the second comb tooth 321 can be connected to the corresponding rotating shaft 33 and fan blade 34 to form an integral structure.

[0086] In some embodiments, such as Figure 6 and Figure 7 As shown, the second cover structure 20 may include a connected second cover 21 and a retaining wall 22. The retaining wall 22 is located at the edge of the second cover 21, and the second cover 21 is located on the side of the retaining wall 22 away from the functional layer 30. A second vent 20v is formed on the second cover 21. It is understood that the depth of the second vent 20v is equal to the thickness of the second cover 21.

[0087] The second cover plate 21 and the barrier wall 22 can be an integral structure. For example, the second cover plate 21 and the barrier wall 22 can be made of glass, such as borosilicate glass, to facilitate bonding with the functional layer 30. Of course, the second cover plate 21 and the barrier wall 22 can also be made of other materials, such as silicon wafers.

[0088] Figure 10 This is a cross-sectional view of a MEMS heat dissipation device provided in some other embodiments of this disclosure. Figure 11 for Figure 10 A schematic diagram of airflow during heat dissipation in a MEMS heat dissipation device. Figure 10 The MEMS heat dissipation device shown is Figure 7 , Figure 8 Similarly, the difference lies in, in Figure 10 In the middle, the orthographic projection of the second vent 20v below the same fan blade 34 on the reference plane is located on the same side of the orthographic projection of the corresponding rotating shaft 33 on the reference plane, for example, on the side of the orthographic projection of the corresponding rotating shaft 33 on the reference plane that is close to the center of the second chamber Sp2.

[0089] exist Figure 10 In this configuration, a greater number of second vents 20v are provided below each fan blade 34. The orthographic projections of multiple second vents 20v corresponding to the same fan blade 34 onto the reference plane are distributed on both sides of the orthographic projection of the corresponding rotating shaft 33 onto the reference plane. For example... Figure 11 As shown, when the fan blade 34 swings downward, the gas in the second chamber Sp2 is ejected from the second vent 20v near the middle, while the second vent 20v at the edge position will have some air intake; when the fan blade 34 swings upward, the second vent 20v near the middle of the second chamber Sp2 will have some air intake, while the second vent 20v near the edge of the second chamber Sp2 will eject air.

[0090] Figure 10 The MEMS heat dissipation device shown can increase the heat dissipation area and improve heat dissipation efficiency.

[0091] This disclosure also provides a method for fabricating the above-mentioned MEMS heat dissipation device, including:

[0092] S1, Forming the second cover plate structure 20.

[0093] S2. A first cover plate structure 10 and a functional layer 30 are formed in sequence, and a second cover plate structure 20 is bonded to the side of the functional layer 30 away from the first cover plate structure 10. The second cover plate structure 20 and the functional layer 30 form a second chamber Sp2. A second vent 20v is provided on the second cover plate structure 20. The first cover plate structure 10 and the functional layer 30 form a first chamber Sp1. A first vent 11v is provided on the first cover plate structure 10 that communicates with the first chamber Sp1.

[0094] The functional layer 30 includes: a fan blade 34, a rotating shaft 33 fixedly connected to the fan blade 34, and an electrostatic drive assembly. The rotating shaft 33 extends along a first direction and is connected to the first cover plate structure 10. The electrostatic drive assembly includes: fixed electrodes 31 located on opposite sides of the rotating shaft 33 along a second direction, and movable electrodes 32 located on opposite sides of the rotating shaft 33 along the second direction. The movable electrodes 32 are fixedly connected to the rotating shaft 33 and spaced apart from the fixed electrodes 31. The second direction intersects the first direction.

[0095] The fixed electrodes 31 on both sides of the rotating shaft 33 are configured to drive the movable electrode 32 and the fan blade 34 to rotate periodically around the rotating shaft 33.

[0096] In some embodiments, the first cover structure 10 includes a support frame 12 and a first cover 11. The steps of forming a first cover plate structure 10 and a functional layer 30 stacked sequentially include: providing a frame material layer; forming an insulating layer 40 on one side of the frame material layer, wherein a first interconnecting hole V1 and a second interconnecting hole V2 are formed on the insulating layer 40; forming a functional layer 30, wherein the functional layer 30 further includes a first connecting portion 35 and a second connecting portion 36, wherein the first connecting portion 35 is electrically connected to a fixed electrode 31 and the second connecting portion 36 is electrically connected to a movable electrode 32; bonding a second cover plate structure 20 to the side of the functional layer 30 away from the frame material layer; patterning the frame material layer to form a supporting frame 12, wherein the supporting frame 12 includes a plurality of first frame portions 121 and at least one second frame portion 122 that are insulated from each other, wherein the first connecting portion 35 is electrically connected to the first frame portion 121 through the first interconnecting hole V1 and the second frame portion 122 is electrically connected to the frame material layer through the second interconnecting hole V2; and fixing a first cover plate 11 to the side of the supporting frame 12 away from the functional layer 30.

[0097] Figures 12A to 12L This is a schematic diagram illustrating the specific fabrication process of a MEMS heat dissipation device provided in one example of this disclosure. The fabrication process of MEMS is described below with reference to the accompanying drawings.

[0098] S1. Forming the second cover plate structure 20. Specifically, step S1 includes S11 and S12:

[0099] S11, such as Figure 12A and Figure 12B As shown, a glass sheet 20a is provided and cleaned. The glass sheet 20a is a high borosilicate glass that is easy to anoly bond, and its thickness is not subject to special requirements.

[0100] S12, then, as Figure 12BAs shown, the glass plate 20a is etched on both the front and back sides to form a second cover plate 21 and a baffle 22 connected as a single unit. A second vent 20v is provided on the second cover plate 21. The etching process can be isotropic etching, laser-modified etching, or other suitable processes, without special requirements.

[0101] S2. A first cover plate structure 10 and a functional layer 30 are formed in sequence, and a second cover plate structure 20 is bonded to the side of the functional layer 30 away from the first cover plate structure 10. Specifically, step S2 includes:

[0102] S21, such as Figure 12C As shown, a frame material layer 12a is provided and cleaned. The frame material layer 12a is, for example, a silicon wafer with a resistivity of less than 0.05 Ω·cm, and can be P-type or N-type, with no special requirements on the thickness.

[0103] S22, such as Figure 12D As shown, an insulating layer 40 is formed on one side of the frame material layer 12a. Specifically, it can be formed using low-pressure chemical vapor deposition (LPCVD), plasma-enhanced chemical vapor deposition (PECVD), or other deposition processes capable of forming dielectric films; no specific limitation is made here. The insulating layer 40 can be silicon nitride, silicon oxide, or other films with good insulation properties that can be processed using semiconductor techniques. Its thickness can be between 0.1 and 5 micrometers; no special limitation is made here.

[0104] S23, such as Figure 12E As shown, a first interconnect via V1 and a second interconnect via V2 are etched on the insulating layer 40. The etching process can be either a dry process or a wet process, and no special restrictions are imposed here.

[0105] S24. A functional layer 30 is formed on the side of the insulating layer 40 away from the frame material layer.

[0106] Specifically, such as Figure 12F As shown, a functional material layer 31a is formed on the side of the insulating layer 40 away from the frame material layer. It can be formed by chemical vapor deposition (CVD) or epitaxial process. Simultaneous doping is required to make the functional material layer 31a a low-resistivity silicon with a resistivity of less than 0.05 Ω·cm. It can be P-type or N-type, and the thickness is between 10 micrometers and 100 micrometers without special restrictions. To ensure the subsequent bonding power, thinning and chemical mechanical polishing (CMP) processes can be added after deposition to improve the flatness of the silicon surface.

[0107] After that, as Figure 12GAs shown, the functional material layer 31a is patterned to form a functional layer 30 including a fan, a rotating shaft 33, a fixed electrode 31, a movable electrode 32, a first connecting portion 35, and a second connecting portion 36. The etching process used in the patterning process can be deep reactive ion etching (DRIE), which can achieve a high aspect ratio.

[0108] S25, such as Figure 12H As shown, the second cover plate structure 20 is bonded to the functional layer 30, and the second cover plate structure 20 and the functional layer 30 form a second chamber Sp2, and the second vent 20v is connected to the second chamber Sp2.

[0109] It should be noted that in this embodiment of the disclosure, step S1 is described as being performed before step S21. Step S1 can also be performed after step S21, as long as step S1 is completed before step S25.

[0110] S26, such as Figure 12I As shown, a first pad 51 and a second pad 52 are formed on the side of the frame material layer 12a away from the functional layer 30. A metal material layer can be deposited first, and then patterned to form the first pad 51 and the second pad 52. The deposition process can be PVD, electroplating, or other suitable semiconductor processes; no specific limitations are specified here.

[0111] S27, such as Figure 12J and Figure 12K As shown, the frame material layer 12a is patterned to form a support frame 12, which includes a first frame portion 121 and a second frame portion 122 spaced apart from each other. Figure 12J A cross-sectional view of the frame material layer 12a is shown after being graphically represented. Figure 12K A top view is shown after the frame material layer 12a is patterned. The etching process used in the patterning process can be deep reactive ion etching (DRIE), wet etching, or other processes that can create cavities. Afterward, the insulating layer 40 is etched to remove the insulating layer 40 in the areas where the fan blade 34, the shaft 33, the fixed electrode 31, and the movable electrode 32 are located (this can be removed by dry or wet etching). For example, the inner wall of the supporting frame 12 defines a frame-shaped area, and the insulating layer 40 in the frame-shaped area is removed.

[0112] S28, such as Figure 12L As shown, a first cover plate 11 is provided, and the first cover plate 11 is cleaned and then etched to form a first vent 11v penetrating the first cover plate 11, as well as an avoidance notch. The first cover plate 11 can be high borosilicate glass that is easy to anoly bond, and the thickness is not subject to special requirements. To ensure that wafer warpage caused by bonding stress is reduced, the thicknesses of the first cover plate 11 and the second cover plate structure 20 can be the same.

[0113] S29, such as Figure 12M As shown, the first cover plate 11 and the support frame 12 are anodized. After bonding, the first cover plate 11, the support frame 12 and the functional layer 30 form a first cavity, the first vent 11v is connected to the first cavity, and the first pad 51 and the second pad 52 are exposed by the avoidance notch 11a.

[0114] exist Figures 12A to 12M In the fabrication process shown, the second vent 20v is formed before the second cover plate structure 20 is bonded to the functional layer 30. In other examples, the second vent 20v can also be etched to form after bonding. Figure 13 A schematic diagram illustrating the formation of a second vent 20V during the fabrication process of a MEMS heat dissipation device provided in another example of this disclosure, as shown below. Figure 13 As shown, after etching to form the second cover plate 21 and the barrier 22, the barrier 22 can be bonded to the functional layer 30. Then, the second cover plate 21 can be etched to form the second vent 20v. This can increase process reliability and reduce the risk of glass fragments.

[0115] In addition, after the baffle 22 is bonded to the functional layer 30, and before the second cover plate 21 is etched to form the second vent 20v, the second cover plate 21 can be thinned to effectively shorten the depth of the second vent 20v, thereby reducing the ineffective range of the jet air, ensuring that the high-speed gas is delivered to the cooling position as soon as possible, and improving the heat dissipation efficiency.

[0116] In the above examples, the first cover plate 11 and the second cover plate 21 are glass cover plates, but they can also be silicon wafers. The bonding process of the first cover plate 11 and the second cover plate 21 can also be adjusted to a bonding process suitable for silicon wafers, such as silicon-silicon bonding, metal hot pressing bonding, eutectic bonding, etc.

[0117] This disclosure also provides an electronic device, including the MEMS heat dissipation device and the element to be cooled as described in the above embodiments. The first cover plate structure is located on the side of the second cover plate structure away from the element to be cooled, and the second vent 20v is positioned towards the element to be cooled, thereby allowing the airflow ejected from the second chamber Sp2 to effectively cool the element to be cooled.

[0118] The electronic device disclosed herein can be a wearable device or other miniaturized electronic device. The MEMS heat dissipation device is small in size (on the millimeter scale), meeting the heat dissipation requirements of miniaturized electronic devices, and operates with lower noise and lower power consumption. The layer structure design of the MEMS heat dissipation device can fully utilize mature semiconductor processes and materials for fabrication, without being limited by special processes, resulting in lower process costs.

[0119] It is understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of this disclosure, and this disclosure is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and substance of this disclosure, and these modifications and improvements are also considered to be within the scope of protection of this disclosure.

Claims

1. A MEMS heat dissipation device, characterized in that, include: A first cover plate structure and a functional layer are stacked together, the first cover plate structure and the functional layer form a first chamber, and the first cover plate structure has a first vent that communicates with the first chamber. The second cover plate structure is located on the side of the functional layer away from the first cover plate structure, and together with the functional layer, forms a second chamber; the second cover plate structure is provided with a second vent that communicates with the second chamber. The functional layer includes: fan blades, a rotating shaft fixedly connected to the fan blades, and an electrostatic drive assembly. The rotating shaft extends along a first direction and is connected to the first cover plate structure. The electrostatic drive assembly includes: fixed electrodes located on opposite sides of the rotating shaft along a second direction, and movable electrodes located on opposite sides of the rotating shaft along the second direction. The movable electrodes are fixedly connected to the rotating shaft and spaced apart from the fixed electrodes. The second direction intersects the first direction. The fixed electrodes on both sides of the rotating shaft are configured to drive the movable electrode and the fan blade to rotate periodically around the rotating shaft.

2. The MEMS heat dissipation device according to claim 1, characterized in that, The fixed electrode includes a plurality of first comb teeth arranged along the first direction and extending along the second direction, and the movable electrode includes a plurality of second comb teeth arranged along the first direction and extending along the second direction. On the same side of the rotating shaft, the first comb teeth and the second comb teeth are alternately arranged in the first direction.

3. The MEMS heat dissipation device according to claim 2, characterized in that, The lengths of both the first and second comb teeth are between 2 micrometers and 100 micrometers. And / or, the spacing between the first comb teeth and the second comb teeth arranged along the first direction is between 0.1 micrometers and 5 micrometers.

4. The MEMS heat dissipation device according to claim 1, characterized in that, The first cover structure includes: a support frame and a first cover plate fixedly connected, the first cover plate being located on the side of the support frame away from the functional layer, and the first vent penetrating the first cover plate; The MEMS heat dissipation device further includes: The first pad is fixed on the support frame and electrically connected to the fixed electrode through the support frame, and is used to provide an AC signal to the fixed electrode. The second pad is fixed on the support frame and electrically connected to the movable electrode through the support frame, and is used to provide a fixed voltage signal to the movable electrode; the first pad and the second pad are insulated from each other.

5. The MEMS heat dissipation device according to claim 4, characterized in that, The first cover plate structure further includes: an insulating layer, wherein the insulating layer has a first interconnection hole and a second interconnection hole. The functional layer further includes: a first connecting portion and a second connecting portion with an insulating gap, the first connecting portion being electrically connected to the fixed electrode and electrically connected to the support frame through the first interconnecting hole; the second connecting portion being electrically connected to the movable electrode through the rotating shaft and electrically connected to the support frame through the second interconnecting hole.

6. The MEMS heat dissipation device according to claim 5, characterized in that, The support frame is provided with multiple isolation slots, which divide the support frame into multiple first frame parts and at least one second frame part. The first pad is electrically connected to the first frame part, and the second pad is electrically connected to the second frame part. The first connecting part is electrically connected to the first frame part through the first interconnecting hole, and the second connecting part is electrically connected to the second frame part through the second interconnecting hole.

7. The MEMS heat dissipation device according to any one of claims 1 to 6, characterized in that, The number of second vents is multiple, and the orthographic projection area of ​​the first vent on the reference plane is greater than the sum of the orthographic projection areas of the multiple second vents on the reference plane; And / or, The distance from the functional layer to the second vent is less than the distance from the functional layer to the first vent.

8. The MEMS heat dissipation device according to any one of claims 1 to 6, characterized in that, The size of the first vent in the first direction is 0.8 to 1.2 times the size of the fan blade in the first direction, and the size of the first vent in the second direction is greater than the size of the fan blade in the second direction.

9. The MEMS heat dissipation device according to any one of claims 1 to 6, characterized in that, The orthographic projection of the extension line of the shaft axis onto the reference plane is outside the orthographic projection of the second vent onto the reference plane. The reference plane is a plane perpendicular to the arrangement direction of the first cover plate structure and the second cover plate structure.

10. The MEMS heat dissipation device according to any one of claims 1 to 6, characterized in that, The size of the second vent in the first direction is 0.8 to 1.2 times the size of the fan blade in the first direction.

11. The MEMS heat dissipation device according to any one of claims 1 to 6, characterized in that, The functional layer includes at least two fan blades arranged along the second direction, each fan blade being fixedly connected to a corresponding rotating shaft, and a fixed electrode being provided between the rotating shafts connected to adjacent two fan blades; the adjacent two fan blades have a spacing of 5 micrometers to 50 micrometers in the untwisted state.

12. The MEMS heat dissipation device according to any one of claims 1 to 6, characterized in that, The fan blades, the rotating shaft, and the electrostatic drive assembly are made of the same material.

13. A method for fabricating a MEMS heat dissipation device, characterized in that, include: Forming a second cover plate structure; A first cover plate structure and a functional layer are formed and stacked sequentially. A second cover plate structure is bonded to the side of the functional layer away from the first cover plate structure. The second cover plate structure and the functional layer form a second chamber. A second vent is provided on the second cover plate structure to communicate with the second chamber. The first cover plate structure and the functional layer form a first chamber. A first vent is provided on the first cover structure to communicate with the first chamber. The functional layer includes: fan blades, a rotating shaft fixedly connected to the fan blades, and an electrostatic drive assembly. The rotating shaft extends along a first direction and is connected to the first cover plate structure. The electrostatic drive assembly includes: fixed electrodes located on opposite sides of the rotating shaft along a second direction, and movable electrodes located on opposite sides of the rotating shaft along the second direction. The movable electrodes are fixedly connected to the rotating shaft and spaced apart from the fixed electrodes. The second direction intersects the first direction. The fixed electrodes on both sides of the rotating shaft are configured to drive the movable electrode and the fan blade to rotate periodically around the rotating shaft.

14. The preparation method according to claim 13, characterized in that, The first cover plate structure includes a support frame and a first cover plate; The steps of forming a first cover plate structure and a functional layer stacked sequentially, and bonding the second cover plate structure to the side of the functional layer away from the first cover plate structure, include: Provide a frame material layer; An insulating layer is formed on one side of the frame material layer, and a first interconnection hole and a second interconnection hole are formed on the insulating layer; The functional layer is formed, and the functional layer further includes a first connecting portion and a second connecting portion, wherein the first connecting portion is electrically connected to the fixed electrode and the second connecting portion is electrically connected to the movable electrode; The second cover plate structure is bonded to the side of the functional layer away from the frame material layer; The frame material layer is patterned to form a support frame, the support frame including a plurality of first frame portions and at least one second frame portion that are insulated from each other, wherein the first connecting portion is electrically connected to the first frame portion through the first interconnecting hole, and the second frame portion is electrically connected to the frame material layer through the second interconnecting hole; The first cover plate is fixed to the side of the support frame away from the functional layer.

15. An electronic device, characterized in that, It includes a heat dissipation element and a MEMS heat dissipation device according to any one of claims 1 to 12, wherein the first cover plate structure is located on the side of the second cover plate structure away from the heat dissipation element.

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