Silicon-based piezoelectric fan device, preparation method and electronic device

Abstract

The invention discloses a silicon-based piezoelectric fan device, a preparation method and an electronic device, and belongs to the field of micro electro mechanical systems. A plurality of supporting and reinforcing structures are arranged in an oscillator cavity of the fan body structure, and the rigidity of the periphery of the oscillator cavity is reinforced through the supporting and reinforcing structures so as to improve the resonant frequency. And the thickness of the middle vibrating diaphragm area of the fan main body structure is smaller than that of the periphery, so that the structural form that the thickness of the middle vibrating diaphragm area is small is formed, the displacement of the middle vibrating diaphragm area is improved, and therefore the cavity volume change caused by vibrator vibration in one period is improved. Noise of the fan can be reduced, the amplitude of the vibrator is improved, the jet speed and flow are increased, and the production cost is reduced.

Description

Technical Field

[0001] This invention relates to the field of microelectromechanical systems (MEMS), and more specifically, to a silicon-based piezoelectric fan device, its preparation method, and an electronic device. Background Technology

[0002] Mobile phones, tablets, and other terminal electronic products are developing towards high performance, miniaturization, and thinness, resulting in an increasing number of components housed within a unit volume. This increase in the number of electronic components inevitably leads to a corresponding increase in the heat generated by the entire electronic system, causing excessive heat to accumulate on the components and raising the ambient temperature. Therefore, the demand for thin, high-efficiency heat dissipation devices is growing. Existing piezoelectric fans either have high power consumption or low airflow, resulting in poor heat dissipation and high noise levels, all of which limit their further application. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a silicon-based piezoelectric fan device, a manufacturing method, and an electronic device, which can reduce fan noise, increase the amplitude of the oscillator, increase the speed and flow rate of the jet, and reduce production costs.

[0004] The objective of this invention is achieved through the following solution: A piezoelectric fan device includes a fan body structure; the oscillator cavity of the fan body structure is provided with multiple supporting and reinforcing structures, which are used to strengthen the stiffness of the oscillator cavity to increase the resonant frequency; and the thickness of the middle diaphragm region of the fan body structure is lower than that of the surrounding area, forming a structure with a thin middle diaphragm region, thereby increasing the displacement of the middle diaphragm region and thus increasing the cavity volume change caused by the oscillation of the oscillator within one cycle.

[0005] Furthermore, the increase in resonant frequency specifically makes the resonant frequency > 20KHz.

[0006] Furthermore, the shape of the oscillator cavity includes circular, square, or elliptical shapes.

[0007] Furthermore, the main structure of the fan also includes an air outlet, and the geometric dimensions of the oscillator cavity and the air outlet satisfy the Helmholtz resonance frequency formed by the cavity and the air outlet, which is comparable to the resonant frequency of the oscillator.

[0008] Furthermore, the base material of the oscillator in the main fan structure is silicon.

[0009] Furthermore, the oscillator includes oscillator structure one and oscillator structure two, each composed of two silicon wafers with piezoelectric thin film material, and the two silicon wafers are mirror-symmetrical.

[0010] A method for fabricating a silicon-based piezoelectric fan device, comprising the following steps to prepare an oscillator structure: Step (a): Prepare the substrate silicon wafer; Step (b): A first electrode is grown on the first surface of the silicon wafer; Step (c) involves growing a piezoelectric thin film material on the first electrode; Step (d): Pattern the growth of the second electrode; Step (e) involves etching or wet etching the piezoelectric thin film material to form an opening in the piezoelectric thin film material, exposing the lower electrode. Step (f) involves forming a cavity on the second surface of the silicon wafer. The cavity has a structure with reinforced edges and a thin center. Through steps (a) to (f), a single-sided piezoelectric thin film oscillator structure is formed, and this oscillator structure is used to prepare the oscillator of the piezoelectric fan device.

[0011] A method for fabricating a silicon-based piezoelectric fan device, comprising the following steps to prepare an oscillator structure: Step (a): Prepare the substrate silicon wafer; Step (b): Growing bottom electrodes on both sides of the silicon wafer; Step (c): Double-sided growth of piezoelectric thin film material; Step (d): Double-sided patterned growth of the top electrode; Step (e) involves double-sided etching or wet etching of the piezoelectric thin film material to form an opening in the piezoelectric thin film material, exposing the lower electrode and protecting the piezoelectric thin film surface. Through steps (a) to (e), a double-sided piezoelectric thin film oscillator structure is formed, and this oscillator structure is used to prepare the oscillator of the piezoelectric fan device.

[0012] A silicon-based piezoelectric fan device includes a single-sided piezoelectric thin-film oscillator structure and a double-sided piezoelectric thin-film oscillator structure as described above, with the two oscillator structures vibrating in opposite directions. The single-sided piezoelectric thin-film oscillator structure is etched to form a cavity, while the double-sided piezoelectric thin-film oscillator structure has piezoelectric thin films grown on both sides to double the driving capability, thereby further increasing the vibration amplitude.

[0013] A silicon-based piezoelectric fan device employs two single-sided piezoelectric thin-film vibrator structures and a double-sided piezoelectric thin-film vibrator structure as described above, stacked and integrated together to form two jet cavities, A and B. When cavity A is compressed, cavity B expands to maximize the amplification of the jet.

[0014] A silicon-based piezoelectric fan device employs two cavity structures stacked and integrated with the double-sided piezoelectric thin film oscillator structure described above, forming two jet cavities, A and B. When cavity A is compressed, cavity B expands, maximizing the amplification of the jet.

[0015] Furthermore, the cavity structure is made of silicon wafer with a size of 4 / 6 / 8 / 12 inches and a thickness in the range of 200~500 micrometers. The irregular cavity is formed by one-step deep silicon etching or wet etching.

[0016] A silicon-based piezoelectric fan device can arrange the single-sided piezoelectric thin film vibrator structure, the double-sided piezoelectric thin film vibrator structure, and the cavity structure as described above in an array to increase the total exhaust volume.

[0017] Furthermore, the combination is specifically achieved through bonding, bonding, or welding.

[0018] Furthermore, the two cavity structures are only used to form cavities, and the outer surfaces can be used for mounting or attaching.

[0019] An electronic device comprising a piezoelectric fan device as described in any of the preceding claims.

[0020] The beneficial effects of this invention include: This invention increases the resonant frequency by strengthening the rigidity of the surrounding area, making the resonant frequency greater than 20kHz, which is in the ultrasonic band, thus reducing fan noise. Secondly, by reducing the thickness of the middle diaphragm area, the displacement of the middle diaphragm area is increased as much as possible, thereby increasing the cavity volume change caused by the oscillator vibration within one cycle, and increasing the jet velocity and flow rate.

[0021] The substrate structure of this invention uses a silicon wafer instead of an expensive SOI wafer, and the structure is fabricated with as few photolithography steps as possible, thereby reducing production costs.

[0022] The cavity structure of this invention adopts an asymmetrical design, with a single-sided piezoelectric film on one side and a double-sided piezoelectric film on the other side of the oscillator. This improves the driving capability and vibration amplitude under the same low voltage, thereby enhancing the jet output capability. Furthermore, by stacking multiple cavities, this invention can further enhance the jet output capability. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is an exploded view of Example 1; Figure 2 This is an assembly drawing of Example 1; Figure 3This is a schematic diagram of the first-order mode of Example 1; Figure 4 This is a schematic diagram of the preparation method process in Example 1; Figure 5 This is a schematic diagram of the structure of Example 2; Figure 6 This is a schematic diagram of the oscillator's operating modes; Figure 7 This is a process diagram for fabricating an oscillator with a double-sided piezoelectric thin film. Figure 8 This is a schematic diagram of the structure of Example 3; Figure 9 A schematic diagram of the structure forming the irregular cavity; Figure 10 This is a schematic diagram of the structure of Example 4; Figure 11 This is a schematic diagram of the structure of Example 5; In the figure, 11-silicon wafer, 11A-oscillator structure one (single-sided PZT), 11B-oscillator structure two (double-sided PZT), 11C-cavity structure, 116-support and reinforcement structure, 130-air outlet, 113-upper electrode, 114-opening, 111-lower electrode, 112-piezoelectric thin film material, 115-cavity. Detailed Implementation

[0025] All features disclosed in all embodiments of this specification, or steps in all methods or processes implied in the disclosure, may be combined and / or extended or replaced in any way, except for mutually exclusive features and / or steps.

[0026] In view of the problems mentioned in the background, the inventors of this application, after further inventive thinking, believe that: in the relevant existing solutions, the PZT-SOI MEMS fabrication scheme is complex, requiring complex photolithography, etching and other multi-step processes (at least five photomasks are needed: PZT upper electrode pattern, PZT pattern, PZT lower electrode pattern, SOI top silicon pattern, and SOI bottom silicon pattern), which is difficult to manufacture and has high production costs; the fabrication scheme based on bulk ceramic PZT has the following drawbacks: firstly, the thickness is relatively large, and secondly, the driving voltage is high, requiring tens to hundreds of volts. Therefore, its own driving power consumption is relatively large, and the oscillator material is generally stainless steel, which has high density and large mass, requiring even greater driving force to obtain a large amplitude. Based on the above shortcomings, the present invention proposes a low-cost piezoelectric fan technology solution.

[0027] More specifically, as a first aspect of this application, Embodiment 1 specifically provides a piezoelectric fan device. This embodiment specifically describes a silicon-based piezoelectric fan device, with the structure as follows: Figure 1 and Figure 2As shown, the detailed description is as follows: The main structure of the fan includes an oscillator; the oscillator includes oscillator structure one 11A and oscillator structure two 11B. In this embodiment, oscillator structure one is a single-sided PZT material body, and oscillator structure two is a double-sided PZT material body. Oscillator structure one 11A and oscillator structure two 11A are each composed of two silicon wafers with piezoelectric thin film material. The two silicon wafers are mirror symmetrical. 116 is a supporting and reinforcing structure used to improve the resonant frequency of the diaphragm. Multiple structures are set in the cavity to make the resonant frequency > 20KHz. 130 is the air outlet. 113 is the upper electrode. It is particularly noteworthy that the cavity body formed in this embodiment is circular, but it can also be square, elliptical, etc. The geometric dimensional relationship between the cavity and the air outlet 130 satisfies the Helmholtz resonance frequency formed by the cavity and the outlet, which is comparable to the resonant frequency of the oscillator, which can amplify the output of the jet and improve the energy utilization efficiency. The first-order mode of this embodiment is as follows: Figure 3 As shown.

[0028] The advantage of the structural design in Example 1 is that by strengthening the rigidity of the surrounding area, the resonant frequency can be increased to be greater than 20kHz, which is in the ultrasonic band, thereby reducing fan noise. Secondly, by reducing the thickness of the middle diaphragm area, the displacement of the middle diaphragm area can be increased as much as possible, which can increase the cavity volume change caused by the oscillator vibration within one cycle, thereby increasing the jet velocity and flow rate.

[0029] Furthermore, as a second aspect of this application, during the implementation of the preparation method in Example 1, such as Figure 4 As shown, a silicon wafer is used as the main material, where 11 is the silicon wafer, 111 is the lower electrode (PZT material lower electrode), 112 is the piezoelectric thin film material, and 113 is the upper electrode. The process of forming the oscillator structure (11A / 11B) is as follows: Step (a), prepare the silicon wafer substrate by cleaning and other treatments; Step (b) grow the lower electrode 111 on the silicon wafer 11; Step (c), grow the piezoelectric thin film material 112; Step (d), grow the upper electrode 113 by patterning; Step (e), etch or wet-etch the piezoelectric thin film material to form an opening 114 on the piezoelectric thin film material, exposing the lower electrode 111 and protecting the piezoelectric thin film surface; Step (f), etch the back side to form an irregular cavity 115, the cavity structure being a reinforced structure around the perimeter and a thinner structure in the middle area. Through steps (a) to (f), a single-sided piezoelectric thin film oscillator structure can be formed.

[0030] It should be noted that in another embodiment of Example 1, namely Example 2, in order to further improve the amplitude of the oscillator, in the above-mentioned silicon-based piezoelectric fan device, one side adopts the single-sided piezoelectric thin-film oscillator structure as in Example 1, and the other oscillator adopts the double-sided piezoelectric thin-film oscillator structure. In this embodiment, the vibration directions of the two oscillators are opposite. The specific structure of the double-sided piezoelectric thin-film oscillator is as follows... Figure 5As shown, exemplarily, oscillator structure 11A is etched to form a cavity, while oscillator structure 11B has piezoelectric thin films grown on both sides, the purpose of which is to double the driving capability, thereby further increasing the vibration amplitude. The operating modes of the double-sided piezoelectric thin film oscillator are as follows: Figure 6 As shown, the fabrication process of the double-sided piezoelectric thin film oscillator structure is as follows: Figure 7 As shown, a double-sided polished silicon wafer is used as the main material, where 11 is the silicon wafer, 111 is the lower electrode (PZT lower electrode), 112 is the piezoelectric thin film material, and 113 is the upper electrode. The process of forming the oscillator structure (11B) is as follows: Step (a), cleaning and other treatments are performed to prepare the substrate silicon wafer; Step (b), the lower electrode 111 is grown on both sides of the silicon wafer 11; Step (c), the piezoelectric thin film material 112 is grown on both sides; Step (d), the upper electrode 113 is grown on both sides using patterning; Step (e), the piezoelectric thin film material is etched (or wet etched) on both sides to form an opening 114 in the piezoelectric thin film material, exposing the lower electrode 111 and protecting the piezoelectric thin film surface. Through steps (a) to (e), a double-sided piezoelectric thin film oscillator structure can be formed.

[0031] It should be noted that in another embodiment of Example 1, namely in Example 3, as... Figure 8 As shown, this embodiment is a stacked integration scheme. Two single-sided piezoelectric thin film oscillator structures 11A are stacked and integrated with a double-sided piezoelectric thin film oscillator structure 11B. They are combined together by bonding, welding, or other methods to form two jet cavities, A and B. When cavity A is compressed, cavity B expands to maximize the amplification of the jet.

[0032] It should be noted that in another embodiment of Example 1, namely in Example 4, as... Figure 10 As shown, this embodiment still uses a stacked integration scheme. Two cavity structures 11C are employed, each using a silicon wafer 11 with dimensions of 4 / 6 / 8 / 12 inches and a thickness ranging from 200 to 500 micrometers. Irregularly shaped cavities 115 are formed using one-step deep silicon etching or wet etching, and the process is as follows: Figure 9 As shown, it is stacked and integrated with the 11B structure, and combined together by means of bonding, bonding, welding, etc., to form two jet cavities, A and B. When cavity A is compressed, cavity B expands, maximizing the amplification of the jet. Since the two cavity structures 11C are only used to form cavities, their outer surfaces can be used for mounting or surface treatment.

[0033] It should be noted that in another embodiment of Example 1, namely Example 5, since the chip is small, all of the above embodiments can be arranged in an array to increase the total exhaust volume, such as... Figure 11 As shown.

[0034] As a third aspect of this application, an electronic device is provided, including the piezoelectric fan device described in any of the above embodiments.

[0035] In summary, the technical solutions of the embodiments of the present invention have the following advantages: (1) The oscillator cavity is reinforced on all four sides and thin in the middle. While ensuring that the resonant frequency is greater than 20KHz, the amplitude of the oscillator is increased as much as possible to improve the ability to form a jet. (2) The substrate structure uses silicon wafers instead of expensive SOI wafers. Compared with SOI process, fewer photolithography steps are required to complete the structure, reducing production costs and significantly reducing the cost of raw materials. (3) Compared with stainless steel, silicon-based materials have a lower density of 2320 kg / m3, which is less than one-third of the density of stainless steel (7930 kg / m3). Moreover, the Young's modulus of silicon-based materials is about 170 GPa. Therefore, under the same driving force, silicon-based oscillators can obtain a larger amplitude and stronger jet output capability. (4) The form of double-sided piezoelectric film coating on one side of the oscillator improves the driving capability under the same low voltage driving conditions. The typical driving voltage is less than 30Vpp, which increases the vibration amplitude and achieves the ability to improve the jet output.

[0036] The above description is merely the technical principles and preferred embodiments used in this invention. Those skilled in the art will understand that this invention is not limited to the specific embodiments described herein. Various obvious changes, adjustments, and substitutions can be made by those skilled in the art without departing from the scope of protection of this invention. Therefore, although the invention has been described in detail through the above embodiments, this invention is not limited to the above embodiments. Many other equivalent embodiments may be included without departing from the principles and concept of this invention, and the scope of this invention is determined by the scope of the appended claims.

Claims

1. A piezoelectric fan device, characterized in that, The fan body includes a main fan structure; the oscillator cavity of the main fan structure is provided with multiple supporting and reinforcing structures, which are used to strengthen the stiffness of the oscillator cavity to increase the resonant frequency; and the thickness of the middle diaphragm region of the main fan structure is lower than that of the surrounding area, forming a structure with a thin middle diaphragm region, thereby increasing the displacement of the middle diaphragm region and thus increasing the cavity volume change caused by the oscillation of the oscillator within one cycle.

2. The piezoelectric fan device according to claim 1, characterized in that, Specifically, the resonant frequency is increased to a value greater than 20kHz.

3. The piezoelectric fan device according to claim 1, characterized in that, The shape of the oscillator cavity can be circular, square, or elliptical.

4. The piezoelectric fan device according to claim 1, characterized in that, The main structure of the fan also includes an air outlet. The geometric dimensions of the oscillator cavity and the air outlet satisfy the Helmholtz resonance frequency formed by the cavity and the air outlet, which is comparable to the resonant frequency of the oscillator.

5. The piezoelectric fan device according to claim 1, characterized in that, The base material of the oscillator in the main structure of the fan is silicon.

6. The piezoelectric fan device according to claim 5, characterized in that, The oscillator includes oscillator structure one and oscillator structure two. Structure one and structure two are each composed of two silicon wafers with piezoelectric thin film material, and the two silicon wafers are mirror symmetrical.

7. A method for preparing a silicon-based piezoelectric fan device, characterized in that, The oscillator structure is prepared according to the following steps: Step (a): Prepare the substrate silicon wafer; Step (b): Grow a first electrode on the first surface of the silicon wafer; Step (c) involves growing a piezoelectric thin film material on the first electrode; Step (d): Pattern the growth of the second electrode; Step (e) involves etching or wet etching the piezoelectric thin film material to form an opening in the piezoelectric thin film material, exposing the lower electrode. Step (f) involves forming a cavity on the second surface of the silicon wafer. The cavity has a structure with reinforced edges and a thin center. Through steps (a) to (f), a single-sided piezoelectric thin film oscillator structure is formed, and this oscillator structure is used to prepare the oscillator of the piezoelectric fan device.

8. A method for preparing a silicon-based piezoelectric fan device, characterized in that, The oscillator structure is prepared according to the following steps: Step (a): Prepare the substrate silicon wafer; Step (b): Growing bottom electrodes on both sides of the silicon wafer; Step (c): Double-sided growth of piezoelectric thin film material; Step (d): Double-sided patterned growth of the top electrode; Step (e) involves double-sided etching or wet etching of the piezoelectric thin film material to form an opening in the piezoelectric thin film material, exposing the lower electrode and protecting the piezoelectric thin film surface. Through steps (a) to (e), a double-sided piezoelectric thin film oscillator structure is formed, and this oscillator structure is used to prepare the oscillator of the piezoelectric fan device.

9. A silicon-based piezoelectric fan device, characterized in that, It includes the single-sided piezoelectric thin film oscillator structure as described in claim 7 and the double-sided piezoelectric thin film oscillator structure as described in claim 8, and the two oscillator structures vibrate in opposite directions; the single-sided piezoelectric thin film oscillator structure is etched to form a cavity, while the double-sided piezoelectric thin film oscillator structure has piezoelectric thin films grown on both sides to double the driving capability, thereby further increasing the vibration amplitude.

10. A silicon-based piezoelectric fan device, characterized in that, Two single-sided piezoelectric thin film vibrator structures as described in claim 7 and double-sided piezoelectric thin film vibrator structures as described in claim 8 are stacked and integrated together to form two jet cavities, A and B. When cavity A is compressed, cavity B expands to maximize the amplification of the jet.

11. A silicon-based piezoelectric fan device, characterized in that, The two cavity structures are stacked and integrated with the double-sided piezoelectric thin film oscillator structure described in claim 8, and combined together to form two jet cavities, A and B. When cavity A is compressed, cavity B expands to maximize the amplification of the jet.

12. The silicon-based piezoelectric fan device according to claim 11, characterized in that, The cavity structure uses a silicon wafer with dimensions of 4 / 6 / 8 / 12 inches and a thickness in the range of 200~500 micrometers. The thickness of the deposited piezoelectric film is between 1~10μm. The irregular cavity with stiffness reinforcement around the perimeter and thinness in the middle is formed by one-step deep silicon etching or wet etching.

13. A silicon-based piezoelectric fan device, characterized in that, The single-sided piezoelectric thin film vibrator structure as described in claim 7, the double-sided piezoelectric thin film vibrator structure as described in claim 8, and the cavity structure can all be arranged in an array to increase the total exhaust volume.

14. The silicon-based piezoelectric fan device according to claim 10, characterized in that, The components are assembled together using adhesive bonding, bonding, or welding.

15. The silicon-based piezoelectric fan device according to claim 11, characterized in that, The two cavity structures are only used to form cavities, and the outer surfaces can be used for mounting or surface mounting.

16. An electronic device, characterized in that, Includes the piezoelectric fan device as described in any one of claims 1-6.

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