anchoring formations

Abstract

An anchoring structure is disclosed for a micro-electro-mechanical system (MEMS) device including a cap layer, a device layer, and a substrate layer to improve the stress tolerance of the MEMS device. The anchoring structure includes a first anchor portion, a second anchor portion, and a flexible member in the device layer. The first anchor portion and the second anchor portion are connected to two sides of the flexible member, respectively. The first anchor portion is fixed to the cap layer via a first joint portion, and the second anchor portion is fixed to the substrate layer via a second joint portion.

Description

Technical Field

[0001] This invention relates to an anchoring structure, and more particularly to an anchoring structure for use in microelectromechanical systems (MEMS). Background Technology

[0002] Microelectromechanical system (MEMS) components typically consist of a top cap layer, a central device layer, and a bottom substrate layer. Anchoring structures are the fixed points within this structure, used to support other components of the component. They can serve as fulcrums for the movement of other components and may even connect and fix the cap layer, device layer, and substrate layer. Anchoring structures are crucial for maintaining the structural integrity of the component and preventing accidental movement or deformation of components suspended within the component. The design and placement of anchoring structures can significantly impact the performance and reliability of MEMS components.

[0003] A common anchoring structure consists of anchor points on both sides of the component layer, connecting the cover layer and the substrate layer respectively. While this two-sided fixing structure can clamp and form a stable structure, it is susceptible to stress from the cover layer or the substrate layer. For example, deformation caused by temperature changes or external forces can create stress. If the stress originally only acted on the cover layer, because the anchor points connect the cover layer and the substrate layer respectively, the stress will inevitably be transmitted to the substrate layer, and vice versa. This can cause stress to affect the entire MEMS component through the existing anchor point structure. If the stress is too high, it may cause signal offset in the MEMS component.

[0004] However, stress is difficult to avoid for MEMS components. For example, when soldering MEMS components onto a printed circuit board (PCB), the temperature difference between the PCB, solder balls, and component packaging materials will exert stress on the MEMS component. Furthermore, if MEMS components are installed in portable electronic devices, they will inevitably be subjected to external forces during application. Therefore, making MEMS components insensitive to stress becomes extremely important. Summary of the Invention

[0005] This invention proposes an improved anchoring structure to address the problem that stress can affect the overall MEMS device through existing anchoring structures.

[0006] To achieve the above objectives, the present invention provides an anchoring structure applicable to microelectromechanical system (MEMS) components comprising a cover layer, a component layer, and a substrate layer. The anchoring structure includes a first anchoring portion, a second anchoring portion, and a flexible member located on the component layer. The first anchoring portion and the second anchoring portion are respectively connected to both sides of the flexible member. The first anchoring portion is fixed to the cover layer via a first joint, and the second anchoring portion is fixed to the substrate layer via a second joint.

[0007] By adopting an anchoring structure that includes a first anchoring part and a second anchoring part that respectively connect the cover layer and the substrate layer, and by connecting the first anchoring part and the second anchoring part through the flexible member, the stress transmission between the cover layer and the substrate layer can be reduced. Even under high stress, signal deviation is less likely to occur, thus further improving product reliability. Attached Figure Description

[0008] Figure 1 This is a cross-sectional view of the anchoring structure according to the first embodiment of the present invention. Figure 2A This is a top view schematic diagram of an element having the anchoring structure of the second embodiment of the present invention; Figure 2B It is along Figure 2A A cross-sectional view along section line A-A'; Figure 3 It is a cross-sectional schematic diagram of an element having the anchoring structure of the third embodiment of the present invention; Figure 4 This is a cross-sectional schematic diagram of the anchoring structure according to the fourth embodiment of the present invention. [Figure Number Reference Guide] 1. Cap layer 11. Auxiliary ribs 2 Component Layer 21 First Anchorage 22 Second Anchorage 23 Flexible components 3. Substrate layer 4 First joint 5 Second joint G gap Detailed Implementation

[0009] To provide a better understanding of the structural features and effects achieved by the present invention, preferred embodiments and detailed descriptions are provided below:

[0010] Please see Figure 1This is a cross-sectional view of the anchoring structure according to the first embodiment of the present invention, which is applied to a MEMS device comprising a cap layer 1, a device layer 2, and a substrate layer 3. The anchoring structure includes a first anchoring portion 21, a second anchoring portion 22, and a flexible element 23 located in the device layer 2. The first anchoring portion 21 and the second anchoring portion 22 are respectively connected to both sides of the flexible element 23, and the first anchoring portion 21 is fixed to the cap layer 1, while the second anchoring portion 22 is fixed to the substrate layer 3. That is, the first anchoring portion 21 is not fixed to the substrate layer 3, and the second anchoring portion 22 is not fixed to the cap layer 1.

[0011] The flexible element 23 is a flexible structure with a highly deformable construction. In MEMS devices, the available materials are often limited due to manufacturing cost considerations. Therefore, one possible approach is to use the same material to fabricate the first anchoring part 21, the second anchoring part 22, and the flexible element 23, but design the flexible element 23 to have a smaller cross-sectional area to form a flexible structure. Of course, if the manufacturing process permits, a different material than that used for the first anchoring part 21 or the second anchoring part 22 can be used to fabricate the flexible element 23. Alternatively, if space permits, the flexible element 23 can be designed to have one or more bending portions, effectively forming a spring-like flexible structure.

[0012] In this embodiment, the first anchoring portion 21 is fixed to the cover layer 1 via a first joint portion 4, and the second anchoring portion 22 is fixed to the substrate layer 3 via a second joint portion 5. The anchoring structure of this first embodiment can also serve as a fulcrum in a MEMS element, connecting the cover layer 1 and the substrate layer 3 respectively. However, unlike in the prior art, the cover layer 1 and the substrate layer 3 are not connected on both sides of an anchor point, but are instead connected to the first anchoring portion 21 and the second anchoring portion 22 respectively. Furthermore, the first anchoring portion 21 and the second anchoring portion 22 are connected by a flexible member 23. In this way, the flexible member 23 can significantly reduce stress transmission between the cover layer 1 and the substrate layer 3.

[0013] For example, when the cover layer 1 is subjected to stress, the stress is reduced by the flexible member 23 before being transmitted to the second anchoring portion 22. Therefore, the impact of the stress on the substrate layer 3 is reduced. Furthermore, the second anchoring portion 22 can suspend internal structures of the MEMS device (such as sensors or actuators), thus preventing these structures from being affected by the stress of the cover layer 1. In other words, the stress or deformation experienced by the cover layer 1 has a reduced impact on the substrate layer 3; similarly, the stress or deformation experienced by the substrate layer 3 also has a reduced impact on the cover layer 1. Accordingly, the anchoring structure of the first embodiment of the present invention can effectively reduce the possibility of signal offset when the MEMS device is subjected to stress, thereby further improving product reliability.

[0014] In practice, there are various manufacturing processes to realize the anchoring structure of the first embodiment. The following example illustrates the overall manufacturing process using one manufacturing process, but it is not intended to limit the anchoring structure of the present invention to be manufactured only by the aforementioned manufacturing process.

[0015] A MEMS device fabrication method includes a first bonding step and a second bonding step. The first bonding step involves fabricating a first bonding portion 4 to connect the first anchor portion 21 and the cover layer 1 together. The second bonding step involves fabricating a second bonding portion 5 to connect the second anchor portion 22 and the substrate layer 3 together. The first and second bonding steps can be various existing wafer bonding processes, such as direct bonding, anodic bonding, eutectic bonding, adhesive bonding, thermocompression bonding, etc.

[0016] The specific manufacturing process includes connecting the first anchoring part 21 and the second anchoring part 22 to both sides of the flexible member 23, and connecting the first anchoring part 21 and the cover layer 1 through a first joining step. At this time, the first anchoring part 21 and the flexible member 23 can serve as a temporary support for suspending the second anchoring part 22, keeping the second anchoring part 22 in a predetermined position. Next, the second anchoring part 22 and the substrate layer 3 are connected through a second joining step. In a typical joining process, the two objects to be joined need to be brought close together by a force. The cover layer 1 and the second anchoring part 22 are not in contact, and the cover layer 1 cannot directly apply force to the second anchoring part 22 to bring it closer to the substrate layer 3. However, when the cover layer 1 approaches the substrate layer 3, the first anchoring part 21 can drive the second anchoring part 22 through the flexible member 23, bringing it closer to the substrate layer 3 to form a joining force, thereby completing the fabrication of the second joining part 5.

[0017] It should be noted that the magnitude of the bonding force applied to the second anchoring portion 22 via the flexible member 23 is affected by the rigidity of the flexible member 23. The rigider the flexible member 23, the greater the bonding force that can be applied to the second anchoring portion 22. However, the coupling force between the first anchoring portion 21 and the second anchoring portion 22 will also be greater. Generally speaking, if it is desired that the flexible member 23 reduces the stress transmission between the cover layer 1 and the substrate layer 3, excessively high coupling forces between the first anchoring portion 21 and the second anchoring portion 22 should be avoided. Therefore, the actual design of the rigidity of the flexible member 23 depends on the user's needs and the selected bonding process parameters.

[0018] On the other hand, if the first bonding step and the second bonding step are processes that require operation at specific high temperatures, such as eutectic bonding or thermoforming, the operating temperature of the first bonding step (approximately equivalent to the melting point of the first bonding portion 4) can be set higher than the operating temperature of the second bonding step (approximately equivalent to the melting point of the second bonding portion 5). This can prevent melting deformation at the location of the first bonding portion 4 when manufacturing the second bonding portion 5.

[0019] As mentioned above, the above examples are merely to illustrate one possible manufacturing process for implementing the anchoring structure of the first embodiment. In other possible manufacturing processes, it is possible to connect the second anchoring portion 22 and the substrate layer 3 first, and then connect the first anchoring portion 21 and the cover layer 1; or, it is possible to connect the second anchoring portion 22 and the substrate layer 3 simultaneously when connecting the first anchoring portion 21 and the cover layer 1. However, regardless of the manufacturing process, because the anchoring structure of the first embodiment connects the first anchoring portion 21 and the second anchoring portion 22 to both sides of the flexible member 23 respectively, it ensures that the first anchoring portion 21 and the second anchoring portion 22 are respectively fixed to the cover layer 1 and the substrate layer 3. Specifically, if the second anchoring part 22 and the substrate layer 3 are connected first, although the substrate layer 3 and the first anchoring part 21 are not in contact, the substrate layer 3 cannot directly apply force to the first anchoring part 21 to bring it close to the cover layer 1. However, when the substrate layer 3 approaches the cover layer 1, the second anchoring part 22 can drive the first anchoring part 21 through the flexible member 23, so that it approaches the cover layer 1 to form a bonding force, thereby completing the fabrication of the first joint part 4.

[0020] In the foregoing embodiments, only the anchoring structure itself has been described. However, in practical applications, MEMS components may have other corresponding structures, and an example is given here for illustration. Please refer to Figures 2A and 2B, where... Figure 2A This is a top view schematic diagram of an element having the anchoring structure of the second embodiment of the present invention. Figure 2B For along Figure 2AA cross-sectional view of section line A-A'.

[0021] The main difference between the anchoring structure of this second embodiment and the first embodiment is that, in this embodiment, two first anchoring portions 21 are provided, and the two first anchoring portions 21 are respectively connected to the outer periphery of the second anchoring portion 22 via two flexible members 23. In this way, when the cover layer 1 approaches the substrate layer 3, the two first anchoring portions 21 can simultaneously drive the second anchoring portion 22 via the flexible members 23, thereby forming a more uniform bonding force. Similarly, in other embodiments of the present invention, three or more first anchoring portions 21 and a corresponding number of flexible members 23 may be provided.

[0022] Furthermore, as explained above, in this embodiment, the first anchoring part 21, the second anchoring part 22, and the flexible member 23 can be made using the same material. However, the flexible member 23 is designed to have a smaller cross-sectional area, thus forming a flexible structure. The advantage of this approach is that the first anchoring part 21, the second anchoring part 22, and the flexible member 23 can be fabricated simultaneously in the component layer 2, which significantly helps to save on manufacturing costs.

[0023] The first anchoring part 21 or the second anchoring part 22 can be used for suspension of the internal structure of the MEMS element, for example from... Figure 2A It can also be seen that the second anchoring part 22 can be suspended by a rotating shaft structure, thereby enabling the MEMS element to form a seesaw-totter type Z-axis accelerometer. The operating principle of the MEMS accelerometer will not be elaborated here; however, as explained above, due to the application of the anchoring structure of this second embodiment, when the cover layer 1 is subjected to stress, the impact of that stress on the substrate layer 3 is reduced, and the impact on the rotating shaft and other structures suspended by the second anchoring part 22 is also reduced. Similarly, when the substrate layer 3 is subjected to stress, the impact of that stress on the cover layer 1 and the structures suspended by the first anchoring part 21 is reduced.

[0024] In addition, although it can be noted that the MEMS element in the figure has an annular structure on the outer periphery, with the cover layer 1 and the substrate layer 3 respectively connected on both sides, this is the frame part of the MEMS element and does not belong to the anchoring structure as known in the art.

[0025] Please see Figure 3The diagram shows a cross-sectional view of an element with an anchoring structure according to the third embodiment of the present invention. The difference from the second embodiment is that in this embodiment, the cover layer 1 has an auxiliary rib 11. The auxiliary rib 11 may include one or more ribs protruding towards the element layer 2, and the auxiliary rib 11 is aligned with the second anchoring portion 22, with a gap G between them. Specifically, during the process of connecting the second anchoring portion 22 and the substrate layer 3 through the second joining step, when a sufficiently large force is applied to the cover layer 1, causing its deformation to exceed the gap G, the auxiliary rib 11 will abut against the second anchoring portion 22 to help bring the second anchoring portion 22 closer to the substrate layer 3 to form a joining force. Once the second joining portion 5 is fabricated and the force applied to the cover layer 1 is stopped, the auxiliary rib 11 will return to maintaining the gap G with the second anchoring portion 22, thereby ensuring that the anchoring structure of the third embodiment can also reduce stress transmission between the cover layer 1 and the substrate layer 3.

[0026] Please refer to the following: Figure 4 The diagram shown is a cross-sectional schematic of the anchoring structure according to the fourth embodiment of the present invention. The main difference from the first embodiment is that this embodiment includes two second anchoring portions 22, which are connected to the outer periphery of the first anchoring portion 21 via two flexible members 23. In this way, when the cover layer 1 approaches the substrate layer 3, the first anchoring portion 21 can simultaneously drive the two second anchoring portions 22 via the flexible members 23, thereby forming a more uniform bonding force. Similarly, in other embodiments of the present invention, three or more second anchoring portions 22 and a corresponding number of flexible members 23 may be provided.

[0027] In summary, compared to the existing MEMS devices that use anchor points fixed on both sides, resulting in poor stress resistance, the present invention improves the anchoring structure by adopting a first anchoring part 21 and a second anchoring part 22 that connect the cover layer 1 and the substrate layer 3 respectively. Moreover, the first anchoring part 21 and the second anchoring part 22 are connected by a flexible member 23. The flexible member 23 can significantly reduce the stress transmission between the cover layer 1 and the substrate layer 3, which helps to avoid the adverse effects of the aforementioned stress on the MEMS device, thereby further improving product reliability.

[0028] It should be emphasized again that although in Figures 1 to 4 the flexible member 23 is simplified as a columnar body made of the same material as the first anchoring part 21 and the second anchoring part 22, those skilled in the art will know that the flexible member 23 can be a flexible structure in the form of a bend; or it can be made of a material different from the first anchoring part 21 or the second anchoring part 22, so that the designer can adjust the center of mass, elastic coefficient, deformation and other characteristics of the flexible member 23.

[0029] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the present invention. All equivalent variations and modifications made in accordance with the shape, structure, features and spirit described in the claims of the present invention should be included within the scope of the claims of the present invention.

Claims

1. An anchoring structure, characterized in that, Applied to a microelectromechanical system (MEMS) component comprising a capping layer, a component layer, and a substrate layer, the anchoring structure includes: The component layer includes a first anchoring portion, a second anchoring portion, and a flexible member, with the first anchoring portion and the second anchoring portion respectively connected to both sides of the flexible member; The first anchoring part is fixed to the cover layer via a first joint, and the second anchoring part is fixed to the substrate layer via a second joint; wherein the first anchoring part is not fixed to the substrate layer, and the second anchoring part is not fixed to the cover layer. The cover layer is provided with an auxiliary rib, which includes one or more ribs protruding toward the element layer. The auxiliary rib is aligned with the second anchoring part, and there is a gap between the auxiliary rib and the second anchoring part. Wherein, the gap is smaller than the deformation of the cover layer caused by the applied force when the second joint is made, so that the auxiliary rib abuts against the second anchoring part to assist the second anchoring part in approaching the substrate layer to form a bonding force; and after the force applied to the cover layer is stopped, the auxiliary rib restores the gap between itself and the second anchoring part.

2. The anchoring structure as described in claim 1, characterized in that, It also includes another first anchoring part and another flexible member, the two first anchoring parts being connected to the outer periphery of the second anchoring part via the two flexible members respectively.

3. The anchoring structure as described in claim 1, characterized in that, The first anchoring part, the second anchoring part, and the flexible member are made of the same material, and the flexible member has a smaller cross-sectional area than the first anchoring part and the second anchoring part.

4. The anchoring structure as described in claim 1, characterized in that, The melting point of the first joint is higher than that of the second joint.

5. The anchoring structure as described in claim 1, characterized in that, The melting point of the first joint is lower than that of the second joint.

6. The anchoring structure as described in claim 1, characterized in that, The second anchoring part is used for the internal structure suspension of the microelectromechanical system component.

7. The anchoring structure as described in claim 1, characterized in that, The first anchoring part is used for the suspension of the internal structure of the microelectromechanical system component.

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