Manufacturing method of a MEMS device and the MEMS device

Abstract

The present application provides a manufacturing method of a MEMS device and a MEMS device. The method includes depositing a thin film on at least a part of the surface of a sacrificial layer, processing a through hole in the thin film, removing at least a part of the material in the sacrificial layer covered by the thin film, and discharging the removed material in the sacrificial layer from the through hole to form a cavity in the sacrificial layer, depositing a sealing layer on the surface of the thin film facing away from the sacrificial layer, and sealing the through hole. Compared with the manufacturing method in the prior art, the manufacturing method of the present application only needs to deposit one layer of thin film, shortens the production cycle, and has a reliable on-site sealing ability.

Description

Technical Field

[0001] This application relates to the field of sealing technology, and particularly to a manufacturing method of a MEMS device and a MEMS device. Background Art

[0002] In the prior art, the method for sealing the internal cavity of a device is to deposit a thin film layer on the top of the cavity. The thin film layer has exhaust holes formed by an etching process. After the gas in the internal cavity of the device is exhausted, the exhaust holes are sealed with a film to achieve the sealing of a small cavity. However, this method requires specific silicon-based materials / tools and has a long process cycle time. Although some practical applications achieve sealing through wafer bonding and thin film encapsulation, the manufacturing cost and maintenance work are greatly increased. Moreover, there are process / material limitations even in the front end of the line (FEOL) based on Complementary metal oxidesemiconductor (CMOS). Summary of the Invention

[0003] This application provides a manufacturing method of a MEMS device and a MEMS device, which can reduce the production cycle.

[0004] In a first aspect of this application, a manufacturing method of a MEMS device is provided. The manufacturing method includes depositing a thin film on at least part of the surface of a sacrificial layer, processing through holes in the thin film, removing at least part of the material in the sacrificial layer covered by the thin film, and the removed material in the sacrificial layer is discharged from the through holes to form a cavity in the sacrificial layer, and depositing a sealing layer on the surface of the thin film facing away from the sacrificial layer to seal the through holes.

[0005] Compared with the manufacturing method in the prior art, the manufacturing method of this application only needs to deposit one thin film, shortens the production cycle, and has reliable on-site sealing ability.

[0006] In a possible design, before processing the through holes in the thin film, a structural layer is deposited on at least part of the surface of the sacrificial layer, where the structural layer has a hollowed-out part, and at least part of the material of the thin film is exposed through the hollowed-out part.

[0007] In a possible design, after depositing the structural layer on at least part of the surface of the sacrificial layer, at least part of the material of the structural layer covering the thin film is removed to form a hollowed-out part.

[0008] In a possible design, the material of the thin film is one of a silicon-based material, a polymer, or a metal.

[0009] In a possible design, the through holes are processed in the thin film by laser drilling or surface ablation.

[0010] In a possible design, the manufacturing method of the MEMS device is completed in a vacuum environment.

[0011] The second aspect of this application provides a MEMS device manufactured by the method described above and having the above effects. The MEMS device includes a sacrificial layer, a thin film, a structural layer, and a sealing layer. The sacrificial layer has a cavity. The thin film is disposed on one side of the sacrificial layer where the cavity is located and covers the cavity. The thin film has a through hole that communicates with the cavity. The structural layer is disposed on one side of the sacrificial layer where the cavity is located. The sealing layer includes a first sealing portion that is disposed on the side of the thin film facing away from the sacrificial layer, and the first sealing portion blocks the through hole.

[0012] In a possible design, the structural layer is provided with a hollowed-out portion that is adjacent to the side of the thin film facing away from the sacrificial layer, and the first sealing portion fills at least part of the space of the hollowed-out portion.

[0013] In a possible design, the sealing layer further includes a second sealing portion that is disposed on the side of the structural layer facing away from the sacrificial layer. The first sealing portion and the second sealing portion are connected by a connecting portion, and the connecting portion and the first sealing portion enclose a recessed portion.

[0014] In a possible design, the thickness of the structural layer is greater than the thickness of the thin film.

[0015] It should be understood that the above general description and the following detailed description are only exemplary and do not limit this application. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is the structure of the MEMS device in the prior art;

[0017] Figure 2 is the manufacturing method of the MEMS device provided by this application;

[0018] Figure 3 is the schematic structural diagram of the MEMS device in step S1;

[0019] Figure 4 is the schematic structural diagram of the MEMS device in step S3;

[0020] Figure 5 is the schematic structural diagram of the MEMS device in step S4;

[0021] Figure 6 is the schematic structural diagram of the MEMS device in step S5;

[0022] Figure 7 is the schematic structural diagram of the MEMS device in step S2, where the structural layer does not have a hollowed-out portion;

[0023] Figure 8Schematic structural diagram of the MEMS device in step S2, where the structural layer has a hollowed-out portion;

[0024] Figure 9 Schematic structural diagram of the MEMS device in step S2, where the thin film is not shown.

[0025] Reference numerals:

[0026] 10 - sacrificial layer;

[0027] 101 - cavity;

[0028] 20 - thin film;

[0029] 201 - through hole;

[0030] 30 - structural layer;

[0031] 40 - sealing layer;

[0032] 1 - sacrificial layer;

[0033] 11 - cavity;

[0034] 2 - thin film;

[0035] 21 - through hole;

[0036] 3 - structural layer;

[0037] 31 - hollowed-out portion;

[0038] 32 - step;

[0039] 4 - sealing layer;

[0040] 41 - first sealing portion;

[0041] 42 - second sealing portion;

[0042] 43 - connecting portion.

[0043] The accompanying drawings here are incorporated into the specification and form a part of this specification, showing embodiments consistent with this application, and are used together with the specification to explain the principles of this application. Detailed implementation manners

[0044] To better understand the technical solution of this application, the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0045] It should be clear that the described embodiments are only a part of the embodiments of this application, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in this application without creative efforts belong to the scope of protection of this application.

[0046] The terms used in the embodiments of the present application are for the purpose of describing specific embodiments only and are not intended to limit the present application. The singular forms "a", "the", and "said" used in the embodiments of the present application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0047] It should be understood that the term "and / or" used herein is merely a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " herein generally indicates that the associated objects before and after are in an "or" relationship.

[0048] It should be noted that the orientation terms such as "upper", "lower", "left", and "right" described in the embodiments of the present application are described from the perspective shown in the drawings and should not be construed as a limitation on the embodiments of the present application. In addition, in the context, it should also be understood that when it is mentioned that one element is connected "above" or "below" another element, it can not only be directly connected "above" or "below" another element, but also be indirectly connected "above" or "below" another element through an intermediate element.

[0049] A Micro-Electro-Mechanical System (MEMS) refers to a high-tech device with dimensions in the order of millimeters or even smaller, and its internal structure is generally in the micron or even nanometer scale. In MEMS devices, there are suspended structures, and generally a sacrificial layer removal process is used to manufacture the suspended structures.

[0050] Please refer to Figure 1The method of fabricating a MEMS device using the prior art is as follows. First, a sacrificial layer 10 is etched to remove some of the material inside, forming a cavity 101 in the sacrificial layer 10. A thin film 20 is deposited on top of the cavity 101. Among them, part of the material of the thin film 20 is removed by an etching process to form a through-hole 201. Then, the gas inside the cavity 101 is discharged through the through-hole 201, and the through-hole 201 is sealed with a sealing layer 40 to complete the sealing of the cavity 101. Among them, a structural layer 30 is also deposited on one side of the sacrificial layer 10 where the cavity 101 is provided. The thin film 20 passes through the structural layer 30, and the thickness of the structural layer 30 is the same as that of the thin film 20. After sealing the through-hole 201, the MEMS device is processed by planarization (Chemical Mechanical Polishing, CMP). The applicant has found through research that the prior art manufacturing method cannot achieve on-site sealing after exhausting the gas in the cavity 101, resulting in a longer production cycle time. Moreover, the prior art manufacturing method requires planarization treatment (Chemical Mechanical Polishing, CMP), which easily leads to structural defect problems (such as holes, cracks or delamination). In addition, the prior art manufacturing method limits the use of silicon-based materials to fabricate the thin film 20. Due to the different thermal expansion coefficients from other materials, the thin film 20 is prone to structural defects (such as cracks and delamination).

[0051] To solve at least one of the above problems, the present application provides a method for manufacturing a MEMS device. Please refer to Figure 2 the flowchart shown in Figures 3 - 6 and the structural changes of the MEMS device during the processing shown in

[0052] Step S1: Deposit a thin film 2 on at least part of the surface of the sacrificial layer 1.

[0053] Step S3: Process a through-hole 21 in the thin film 2.

[0054] Step S4: Remove at least part of the material in the sacrificial layer 1 covered by the thin film 2. The removed material in the sacrificial layer 1 is discharged through the through-hole 21 to form a cavity 11 in the sacrificial layer 1.

[0055] Step S5: Deposit a sealing layer 4 on the surface of the thin film 2 facing away from the sacrificial layer 1 to seal the through-hole 21.

[0056] In this embodiment, please refer to Figure 3 as shown, first deposit a thin film 2 on the surface of the sacrificial layer 1, and then please refer to Figure 4 as shown, process a through-hole 21 in the thin film 2. Please refer to Figure 5As shown, at least part of the material of the sacrificial layer 1 covered by the thin film 2 is removed, and the removed material in the sacrificial layer 1 is discharged from the through hole 21 to form a cavity 11 in the sacrificial layer 1. Please refer to Figure 6 As shown, a sealing layer 4 is deposited on the surface of the thin film 2 facing away from the sacrificial layer 1 to seal the through hole 21, thereby completing the sealing of the cavity 11. Compared with the manufacturing method in the prior art, the manufacturing method of the embodiment of the present application only needs to deposit one thin film 2, shortening the production cycle and having a reliable on-site sealing ability.

[0057] Specifically, please refer to Figure 2 As shown, before step S3 (processing a through hole 21 in the thin film 2), there is also step S2:

[0058] In this embodiment, please refer to Figure 7 As shown, a structural layer 3 is deposited on at least part of the surface of the sacrificial layer 1. Among them, please refer to Figure 8 As shown, the structural layer 3 has a hollow part 31, and at least part of the material of the thin film 2 is exposed through the hollow part 31, facilitating the processing of the through hole 21 on the thin film 2 in step S3.

[0059] Among them, multiple structural layers 3 can be deposited on the surface of the sacrificial layer 1, and there is a gap between two adjacent structural layers 3 to form the hollow part 31. Alternatively, part of the material of the structural layer 3 is removed to form the hollow part 31. Specifically, a gas etching process can be used to remove part of the material of the structural layer 3 to form the hollow part 31.

[0060] In addition, the material of the structural layer 3 can be silicon oxide, metal oxide or a material with a thermal expansion coefficient close to that of silicon oxide. On the one hand, when the thermal expansion coefficient of the material of the structural layer 3 is close to that of the thin film 2, and / or when the thermal expansion coefficient of the material of the structural layer 3 is close to that of the sealing layer 4, it is not easy to generate material defect problems (such as holes, cracks or delamination) due to large differences in thermal expansion coefficients, reducing the possibility of sealing failure, and the working reliability and service life of the fabricated MEMS device are relatively high. On the other hand, the manufacturing method of the embodiment of the present application expands the manufacturing process of the structural layer 3 and reduces the manufacturing limitations of MEMS devices.

[0061] Among them, the silicon oxide can include silicon dioxide (SiO2), tetraethoxysilane (TEOS), polysilicon (Poly-Si). The polymer can include polyimide, silicon-on-glass bonding structure material, parylene. The metal oxide can include aluminum oxide (Al2O3), titanium dioxide (TiO2).

[0062] More specifically, in this embodiment, step S2.1 is further included in step S2. Please refer toFigures 7 - 8 As shown, after depositing the structural layer 3 on at least part of the surface of the sacrificial layer 1, at least part of the material of the structural layer 3 covering the thin film 2 is removed to form a hollowed-out portion 31.

[0063] In this embodiment, please refer to Figures 7 - 8 As shown, the structural layer 3 is deposited on at least part of the surface of the sacrificial layer 1, and the structural layer 3 also covers the thin film 2. At least part of the material of the structural layer 3 covering the thin film 2 is removed to form a hollowed-out portion 31, so that at least part of the material of the thin film 2 is exposed through the hollowed-out portion 31, facilitating the implementation of step S3 (drilling a through hole 21 in the thin film 2).

[0064] Among them, in one embodiment, please refer to Figures 8 - 9 As shown, part of the material of the structural layer 3 covering the thin film 2 is removed so that the structural layer 3 has a step 32, and the edge of the thin film 2 is located within the step 32, so as to press the edge of the thin film 2 through the structural layer 3 and reduce the possibility of the thin film 2 falling off from the hollowed-out portion 31.

[0065] In another embodiment (not shown in the figure), all the material of the structural layer 3 covering the thin film 2 is removed to form a hollowed-out portion 31, then there is no step 32, and the structural layer 3 does not press the edge of the thin film 2.

[0066] In the above embodiment, the material of the thin film 2 is one of a silicon-based material, a polymer material, or a metal material.

[0067] Among them, the silicon-based material may include silicon dioxide (SiO2), silicon nitride (Si3N4), tetraethyl orthosilicate (TEOS), polysilicon (Poly-Si), amorphous silicon (a-Si). The polymer material may include polyimide, silicon-on-glass bonding structure material, parylene. The metal material may include aluminum oxide (Al2O3), titanium nitride (TiN), tantalum nitride (TaN), titanium dioxide (TiO2).

[0068] In the material of the above-mentioned thin film 2, a material with a thermal expansion coefficient close to that of the structural layer 3 can be selected to fabricate the thin film 2, or a material with a thermal expansion coefficient close to that of the sealing layer 4 can be selected to fabricate the thin film 2, which is not likely to cause material defect problems (such as holes, cracks or delamination) due to a large difference in thermal expansion coefficient, reducing the possibility of sealing failure, and the fabricated MEMS device has high working reliability and long service life. On the other hand, compared with the prior art method that limits the use of silicon-based materials, the manufacturing method of the embodiment of the present application expands the materials that can be used to fabricate the thin film 2, and further expands the process methods that can be used to process through holes 21, reducing the manufacturing limitations of MEMS devices.

[0069] Among them, when fabricating the thin film 2 with a silicon-based material, the dry etching process can be used to fabricate the through hole 21. When fabricating the thin film 2 with a polymer material, the photolithography or laser process can be used to fabricate the through hole 21. When fabricating the thin film 2 with a metal material, the wet etching process can be used to fabricate the through hole 21.

[0070] In addition, when fabricating the thin film 2 with a metal material, during the sealing process of the through hole 21 of the thin film 2 by the sealing layer 4, the thin film 2 can withstand a higher temperature and is not likely to have problems of defects or delamination, making the MEMS device have high working reliability and long service life.

[0071] In the above embodiment, please refer to Figures 3 - 4 As shown, in step S3, a through hole 21 is fabricated in the thin film 2 by laser drilling or surface ablation.

[0072] In this embodiment, please refer to Figures 3 - 4 As shown, a through hole 21 is fabricated on the thin film 2 by laser drilling or surface ablation. The diameter of the through hole 21 is in the sub-micron range or the nano range, so that when the through hole 21 is sealed by the sealing layer 4, material defect problems (holes and cracks) are not likely to occur, and the problem of delamination between the sealing layer 4 and the thin film 2 is not likely to occur either. The fabricated MEMS device has higher working reliability and longer service life.

[0073] The method of the embodiment of the present application can adjust the size of the through hole 21 according to the area or depth of the material to be removed in the sacrificial layer 1, and control the release time of the material to be removed in the sacrificial layer 1 from the through hole 21. Its manufacturing process is relatively flexible and can meet the usage requirements of different users.

[0074] In the above embodiment, the above steps are completed in a vacuum environment to fabricate the MEMS device, thereby drying the moisture and / or organic gas in the cavity 11, so that the working performance of the MEMS device is maintained at a stable level, and the working reliability and service life of the MEMS device are improved.

[0075] In the above embodiments, the manufacturing method of the present application embodiment does not require planarization of the MEMS device, and it is not easy to derive problems with defects in the oxide material (such as holes, cracks or delamination), so that the working reliability and service life of the MEMS device are relatively high.

[0076] The manufacturing method using the present application embodiment also has the following advantages. It can be compatible with the Complementary Metal Oxide Semiconductor (CMOS) process, is easy to integrate with Si-based fabrication flows, and helps to shorten the production cycle time.

[0077] The second aspect of the present application provides a MEMS device. Please refer to Figure 6 As shown, this MEMS device is prepared by using the manufacturing method of the above MEMS device. This MEMS device includes a sacrificial layer 1, a thin film 2, a structural layer 3, and a sealing layer 4. The sacrificial layer 1 has a cavity 11. The thin film 2 is disposed on the side of the sacrificial layer 1 where the cavity 11 is located and covers the cavity 11. The thin film 2 has a through hole 21, and the through hole 21 communicates with the cavity 11. The structural layer 3 is disposed on the side of the sacrificial layer 1 where the cavity 11 is located. The sealing layer 4 includes a first sealing portion 41. The first sealing portion 41 is disposed on the side of the thin film 2 facing away from the sacrificial layer 1, and the first sealing portion 41 plugs the through hole 21. The MEMS device of the present application embodiment is fabricated by the manufacturing method in the above content and has the effects of the above content, which will not be elaborated here.

[0078] Specifically, please refer to Figure 6 As shown, the structural layer 3 is provided with a hollowed-out portion 31. The hollowed-out portion 31 is adjacent to the side of the thin film 2 facing away from the sacrificial layer 1. The first sealing portion 41 fills at least part of the space of the hollowed-out portion 31 for sealing the through hole 21 of the thin film 2, thereby completing the sealing of the cavity 11.

[0079] Among them, in one embodiment, please refer to Figure 6 As shown, the first sealing portion 41 can fill part of the space of the hollowed-out portion 31. In another embodiment (not shown in the figure), the first sealing portion 41 can fill all the space of the hollowed-out portion 31.

[0080] More specifically, please refer to Figure 6 As shown, the sealing layer 4 further includes a second sealing portion 42. The second sealing portion 42 is disposed on the side of the structural layer 3 facing away from the sacrificial layer 1. The first sealing portion 41 and the second sealing portion 42 are connected by a connecting portion 43, and the connecting portion 43 and the first sealing portion 41 enclose a recessed portion.

[0081] In this embodiment, please refer to Figure 6As shown, the second sealing portion 42 is used to isolate the structural layer 3 from other substances, thereby ensuring the working performance of the structural layer 3.

[0082] Please refer to Figure 6 As shown, the thickness of the structural layer 3 is greater than that of the thin film 2. The thickness of the structural layer 3 is in the micron range, and the thickness of the thin film 2 is in the nanometer range. When the thickness of the thin film 2 is in the nanometer range, it is convenient to observe the formation process of the cavity 11 in the sacrificial layer 1 and whether the inside of the cavity 11 is clean.

[0083] The above are only the embodiments of the present invention. It should be noted here that for those of ordinary skill in the art, improvements can be made without departing from the inventive concept of the present invention, but these all fall within the protection scope of the present invention.

Claims

1. A manufacturing method of a MEMS device, characterized in that, The manufacturing method includes: Depositing a thin film on at least a part of the surface of the sacrificial layer, wherein the thin film includes a metallic material; Depositing a structural layer on at least a part of the surface of the sacrificial layer, wherein the structural layer includes a metal oxide; Removing a part of the material of the structural layer that covers the thin film to form a hollow portion exposing a part of the material of the thin film, and retaining a step that presses against the edge of the thin film; Processing a through hole in the thin film; Removing at least a part of the material of the sacrificial layer covered by the thin film, and the removed material of the sacrificial layer is discharged from the through hole to form a cavity in the sacrificial layer; Depositing a sealing layer on the surface of the thin film facing away from the sacrificial layer to seal the through hole.

2. The manufacturing method of the MEMS device according to claim 1, characterized in that, The material of the thin film is one of a silicon-based material, a polymer, or a metal.

3. The manufacturing method of the MEMS device according to claim 1, characterized in that, The through hole is processed in the thin film by laser drilling or surface ablation.

4. The manufacturing method of the MEMS device according to claim 1, wherein The manufacturing method of the MEMS device is completed in a vacuum environment.

5. A MEMS device, characterized in that, The MEMS device is fabricated by using the manufacturing method of the MEMS device according to any one of claims 1-4, and the MEMS device includes: A sacrificial layer having a cavity; A thin film disposed on one side of the sacrificial layer where the cavity is provided and covering the cavity, the thin film having a through hole that communicates with the cavity; A structural layer disposed on one side of the sacrificial layer where the cavity is provided; A sealing layer including a first sealing portion disposed on the side of the thin film facing away from the sacrificial layer, and the first sealing portion seals the through hole.

6. The MEMS device according to claim 5, wherein The structural layer is provided with a hollow portion adjacent to the side of the thin film facing away from the sacrificial layer; The first sealing portion fills at least a part of the space of the hollow portion.

7. The MEMS device according to claim 6, characterized in that, The sealing layer further includes a second sealing portion disposed on the side of the structural layer facing away from the sacrificial layer; The first sealing portion and the second sealing portion are connected by a connecting portion, and the connecting portion and the first sealing portion enclose a recessed portion.

8. The MEMS device according to claim 5, wherein The thickness of the structural layer is greater than the thickness of the thin film.

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