CN116040572A

CN116040572A - MEMS device and manufacturing method thereof

Info

Publication number: CN116040572A
Application number: CN202211719853.1A
Authority: CN
Inventors: 张兆林
Original assignee: Semiconductor Manufacturing Electronics Shaoxing Corp SMEC
Current assignee: Semiconductor Manufacturing Electronics Shaoxing Corp SMEC
Priority date: 2022-12-30
Filing date: 2022-12-30
Publication date: 2023-05-02

Abstract

A MEMS device and method of manufacturing the same, the method comprising: providing a first substrate and a second substrate, wherein a first surface of the second substrate is formed with a first MEMS structure and a second MEMS structure, and the first substrate comprises a first area and a second area; forming an amorphous silicon structure in a first region of a first surface of a first substrate; forming a protective layer covering the amorphous silicon structure; patterning the second surface of the first substrate to form a first recess and a second recess; etching the second surface of the first substrate to form an air pumping hole; bonding the second surface of the first substrate to the first surface of the second substrate to form a first cavity and a second cavity; etching the protective layer to expose the amorphous silicon structure; pumping air from the first cavity through the amorphous silicon structure and the pumping air holes; a metal layer is deposited over the amorphous silicon structure and the protective layer. The invention forms an amorphous silicon structure to pump air from the first cavity, improves the vacuum degree of the first cavity, and solves the filling and sealing problems of the large-size air pumping holes.

Description

MEMS device and manufacturing method thereof

Technical Field

The invention relates to the technical field of semiconductors, in particular to an MEMS device and a manufacturing method thereof.

Background

MEMS (Micro-Electro-Mechanical System, microelectromechanical system) refers to a Micro system that integrates mechanical components, driving parts, optical systems, electrical control systems into one whole. The MEMS device has the advantages of small volume, low power consumption and the like, and has wide application scenes in a plurality of fields such as smart phones, tablet personal computers, game machines, automobiles, unmanned aerial vehicles and the like. Common MEMS chips include accelerometers, gyroscopes, pressure sensors, microphones, and the like. Like integrated circuits, MEMS devices are also evolving towards high performance, miniaturization, and low cost and integration.

To achieve complete motion detection, it is often necessary to integrate multiple MEMS devices onto a single integrated chip. At present, when the vacuum degree reaches the requirement, two kinds of device integrated wafers are subjected to a laser hole sealing process, and special machine tables are used for hole sealing one by one, but the process has high cost, high process requirement and low efficiency, and cannot be applied to a sealing process with a larger size.

Disclosure of Invention

In the summary, a series of concepts in a simplified form are introduced, which will be further described in detail in the detailed description. The summary of the invention is not intended to define the key features and essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

In view of the problems existing at present, an aspect of the present invention provides a method for manufacturing a MEMS device, including:

providing a first substrate and a second substrate, wherein a first surface of the second substrate is formed with a first MEMS structure and a second MEMS structure, and the first substrate comprises a first area corresponding to the first MEMS structure and a second area corresponding to the second MEMS structure;

forming an amorphous silicon structure in the first region of the first surface of the first substrate;

forming a protective layer covering the amorphous silicon structure on the first surface of the first substrate;

patterning a second surface of the first substrate to form a first recess in the first region and a second recess in the second region;

etching the second surface of the first substrate to form an air pumping hole exposing the amorphous silicon structure;

bonding a second surface of the first substrate to a first surface of the second substrate to form a first cavity in the first region and a second cavity in the second region;

etching the protective layer to expose the amorphous silicon structure;

pumping air from the first cavity through the amorphous silicon structure and the pumping air hole;

a metal layer is deposited over the amorphous silicon structure and the protective layer.

Illustratively, the first substrate is a P-type substrate, and the forming the amorphous silicon structure in the first region of the first surface of the first substrate includes: and corroding the first surface of the P-type substrate by adopting a porous silicon corrosion process to form the amorphous silicon structure.

Illustratively, the first substrate is an N-type substrate, and the forming the amorphous silicon structure in the first region of the first surface of the first substrate includes: etching a deep groove on the first surface of the N-type substrate; forming a P-type semiconductor material in the deep groove; and corroding the P-type semiconductor material by adopting a porous silicon corrosion process to form the amorphous silicon structure.

Illustratively, prior to etching the second surface of the first substrate to form the pumping holes exposing the amorphous silicon structure, further comprising: patterning the second surface of the first substrate to form a third groove in the first region, wherein the position of the third groove corresponds to the amorphous silicon structure; the air pumping hole is positioned in the third groove.

Illustratively, prior to forming the bleed holes, the method further comprises: a gas absorbing layer is formed in the first recess.

Illustratively, the material of the protective layer includes ethyl silicate.

Illustratively, prior to patterning the second surface of the first substrate, the method further comprises: and forming a first bond metal ring structure on the second surface of the first substrate.

Illustratively, prior to bonding the second surface of the first substrate to the first surface of the second substrate, the method further comprises: forming a second bond metal ring structure on the first surface of the second substrate; the bonding the second surface of the first substrate to the first surface of the second substrate includes: and carrying out metal bonding on the first bonding metal ring structure and the second bonding metal ring structure.

Illustratively, the first MEMS structure comprises a comb structure of a gyroscope and the second MEMS structure comprises a comb structure of an accelerometer.

In another aspect the present invention provides a MEMS device made by the method as described above.

The MEMS device and the manufacturing method thereof can form an amorphous silicon structure for exhausting the first cavity, improve the vacuum degree of the first cavity, solve the problem of filling and sealing of the large-size air exhausting hole, further reduce the cost and improve the efficiency.

Drawings

The following drawings are included to provide an understanding of the invention and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and their description to explain the principles of the invention.

In the accompanying drawings:

FIGS. 1A-1B are schematic cross-sectional views of a device obtained by implementing a conventional method for fabricating a MEMS device;

FIG. 2 is a flow chart of a method of fabricating a MEMS device in accordance with an embodiment of the present invention;

FIGS. 3A-3I are schematic cross-sectional views of a MEMS device according to an embodiment of the present invention, wherein the method for fabricating the MEMS device is performed sequentially;

fig. 4A-4F are schematic cross-sectional views of a device obtained by sequentially processing a first substrate of a MEMS device according to another embodiment of the present invention.

Detailed Description

The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the size of layers and regions, as well as the relative sizes, may be exaggerated for clarity. Like numbers refer to like elements throughout.

It will be understood that when an element or layer is referred to as being "on," "adjacent," "connected to," or "coupled to" another element or layer, it can be directly on, adjacent, connected, or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on," "directly adjacent to," "directly connected to," or "directly coupled to" another element or layer, there are no intervening elements or layers present. It will be understood that, although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present invention.

Spatially relative terms, such as "under," "below," "beneath," "under," "above," "over," and the like, may be used herein for ease of description to describe one element or feature's relationship to another element or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use and operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements or features described as "under" or "beneath" other elements would then be oriented "on" the other elements or features. Thus, the exemplary terms "below" and "under" may include both an upper and a lower orientation. The device may be otherwise oriented (rotated 90 degrees or other orientations) and the spatially relative descriptors used herein interpreted accordingly.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term "and/or" includes any and all combinations of the associated listed items.

Embodiments of the invention are described herein with reference to cross-sectional illustrations that are schematic illustrations of idealized embodiments (and intermediate structures) of the invention. In this way, variations from the illustrated shape due to, for example, manufacturing techniques and/or tolerances, are to be expected. Thus, embodiments of the present invention should not be limited to the particular shapes of the regions illustrated herein, but rather include deviations in shapes that result, for example, from manufacturing. For example, an implanted region shown as a rectangle typically has rounded or curved features and/or implant concentration gradients at its edges rather than a binary change from implanted to non-implanted regions. Also, a buried region formed by implantation may result in some implantation in the region between the buried region and the surface over which the implantation is performed. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the actual shape of a region of a device and are not intended to limit the scope of the present invention.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and/or the present specification and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

In order to provide a thorough understanding of the present invention, detailed steps and structures will be presented in the following description in order to illustrate the technical solution presented by the present invention. Preferred embodiments of the present invention are described in detail below, however, the present invention may have other embodiments in addition to these detailed descriptions.

Motion sensors often use MEMS accelerometers (simply accelerometers) in combination with MEMS gyroscopes (simply gyroscopes). The accelerometer detects acceleration and the gyroscope detects angular velocity. To meet the need for low cost, small volume accelerometers and gyroscopes may be integrated on the same substrate.

Taking a single-axis gyroscope as an example, the working principle is as follows: the two moving masses move continuously in opposite directions, and as long as an angular velocity parallel to the movement plane is applied, ke Liao force perpendicular to the movement direction of the masses is generated, so that the masses are displaced, and the displacement is proportional to the applied angular velocity. This displacement will cause a change in capacitance between the comb electrodes and the fixed electrodes of the mass, and therefore the angular rate applied by the input part of the gyroscope is converted into an electrical parameter that can be detected by a dedicated circuit. The working principle of the accelerometer is similar to that of a gyroscope, and the acceleration is detected according to capacitance change generated by displacement of a mass block.

The ideal vacuum level varies for different types of MEMS devices. For example, the main performance index of gyroscopes includes Quality Factor (Quality Factor), which measures the sensitivity of gyroscopes, and its main influencing Factor is the vacuum level in the cavity. The gyroscope is in resonance motion in the cavity when not in operation, and in order to improve sensitivity, the cavity needs to have higher vacuum degree. While the main performance indicators of the accelerometer include damping factors. The damping factor generally has two modes, the first is structural damping, which is produced by friction between structural layers; the second is air viscous damping, which is produced by atmospheric pressure, which is much more powerful than the structural damping. The accelerometer mass block needs to be restored to the original position after deformation, and in order to avoid adsorption between comb teeth, relatively large air viscous damping is needed. That is, in order to ensure high sensitivity and low power consumption, the gyroscope requires a high vacuum, while in order to maintain high performance and reliability, the accelerometer requires a low vacuum.

In order to enable different MEMS devices on the same substrate to have different vacuum degrees, as shown in FIG. 1A, a first substrate 100 is bonded with a second substrate 102, an air extraction hole 101 is etched in the first substrate 100, and air is extracted through the air extraction hole 101 to improve the vacuum degree of a cavity where the air extraction hole 101 is located; after the vacuum degree reaches the requirement, as shown in fig. 1B, a laser hole sealing process is adopted, and a special machine is used for sealing the air suction holes 101 one by one. The process has high cost, high process requirement and low efficiency, and cannot be applied to a sealing process of a large-size air suction hole.

Accordingly, in view of the foregoing technical problems, the present invention provides a method for manufacturing a MEMS device, as shown in fig. 2, which mainly includes the following steps:

step S1, providing a first substrate and a second substrate, wherein a first surface of the second substrate is formed with a first MEMS structure and a second MEMS structure, and the first substrate comprises a first area corresponding to the first MEMS structure and a second area corresponding to the second MEMS structure;

step S2, forming an amorphous silicon structure in the first area of the first surface of the first substrate;

step S3, forming a protective layer covering the amorphous silicon structure on the first surface of the first substrate;

step S4, patterning the second surface of the first substrate to form a first groove in the first area and a second groove in the second area;

step S5, etching the second surface of the first substrate to form a pumping hole exposing the amorphous silicon structure;

step S6, bonding the second surface of the first substrate and the first surface of the second substrate to form a first cavity in the first area and a second cavity in the second area;

step S7, etching the protective layer to expose the amorphous silicon structure;

s8, pumping the first cavity through the amorphous silicon structure and the pumping holes;

and S9, depositing a metal layer on the amorphous silicon structure and the protective layer.

According to the manufacturing method of the MEMS device, the amorphous silicon structure can be formed to be used for exhausting the first cavity, wherein the amorphous silicon structure is used as an auxiliary filling structure of a hole sealing process, so that the problem of filling and sealing of the large-size air exhaust hole is solved, the cost is reduced, and the efficiency is improved.

Next, a method for manufacturing a MEMS device according to an embodiment of the present invention will be described in detail with reference to fig. 3A to 3I, and fig. 3A to 3I are schematic cross-sectional views illustrating a method for manufacturing a MEMS device according to an embodiment of the present invention, which is performed sequentially. Illustratively, the method for manufacturing the MEMS device according to the embodiment of the present invention includes the steps of:

first, step S1 is performed, providing a first substrate and a second substrate, wherein a first surface of the second substrate is formed with a first MEMS structure and a second MEMS structure, and the first substrate includes a first region corresponding to the first MEMS structure and a second region corresponding to the second MEMS structure.

Specifically, as shown in fig. 3A, a first substrate 300 is provided, the first substrate 300 being a bulk silicon substrate, which may be at least one of the following mentioned materials: si, ge, siGe, siC, siGeC, inAs, gaAs, inP, inGaAs or other III/V compound semiconductors, and also include multilayer structures of these semiconductors, or are silicon-on-insulator (SOI), silicon-on-insulator (SSOI), silicon-germanium-on-insulator (S-SiGeOI), silicon-germanium-on-insulator (SiGeOI), germanium-on-insulator (GeOI), and the like. The first substrate 300 includes a first region corresponding to a subsequently formed first MEMS device and a second region corresponding to a subsequently formed second MEMS device. The first MEMS device may be a gyroscope and the second MEMS device may be an accelerometer. In this embodiment, the first substrate 300 may be a P-type substrate, i.e., the first substrate 300 has P-type dopant ions therein.

As shown in fig. 3G, a second substrate 309 is provided, and the second substrate 309 includes a semiconductor base, a device structure, an interconnect structure, and the like. The second substrate 309 may be a bulk silicon substrate, and in particular may be at least one of the following mentioned materials: si, ge, siGe, siC, siGeC, inAs, gaAs, inP, inGaAs or other III/V compound semiconductors, and also include multilayer structures of these semiconductors, or are silicon-on-insulator (SOI), silicon-on-insulator (SSOI), silicon-germanium-on-insulator (S-SiGeOI), silicon-germanium-on-insulator (SiGeOI), germanium-on-insulator (GeOI), and the like. The device structure includes transistors that form part of a control circuit. The transistors include CMOS devices, and may include NMOS devices and PMOS devices, among other semiconductor devices, for example. Illustratively, a dielectric layer is covered over the device structure, and a metal interconnect structure is formed in the dielectric layer.

In one example, as shown in fig. 3G, the first surface of the second substrate 309 is formed with a first MEMS structure and a second MEMS structure, which correspond to the first region and the second region, respectively. Illustratively, the first MEMS structure comprises a comb structure of a gyroscope and the second MEMS structure comprises a comb structure of an accelerometer. The number, size, etc. of the two can be set according to the process requirements of the accelerometer and the gyroscope.

The comb structures may also be referred to as masses, and when the MEMS device is moved, the capacitance between the comb structures and between the comb and the second substrate changes, thereby converting the motion parameters into electrical parameters. In particular, a first surface of the second substrate 309 corresponding to the first region may be patterned to form a plurality of first MEMS structures, and a first surface of the second substrate 309 corresponding to the second region may be patterned to form a plurality of second MEMS structures.

Subsequently, step S2 is performed to form an amorphous silicon structure in a first region of the first surface of the first substrate. The amorphous silicon structure has the characteristic of loose and porous, so that the first cavity of the first MEMS device can be pumped through the amorphous silicon structure to improve the vacuum degree of the first cavity.

In one example, forming the amorphous silicon structure 301 at a first region of a first surface of the first substrate 300 includes the steps of: first, a mask layer, such as a patterned photoresist layer, is formed on a first surface of the first substrate 300, with openings in the photoresist layer corresponding to locations where amorphous silicon structures 301 are to be formed. Next, the exposed first substrate 300 is etched using the patterned mask layer as a mask, using a porous silicon etching process, thereby forming an amorphous silicon structure 301 on the first surface of the first substrate 300.

In this embodiment, the porous silicon etching process may be an anodic etching process. In particular, at almost all doping levels, the P-type substrate may be anodized to form an amorphous silicon structure (also referred to as porous silicon), and thus the amorphous silicon structure 301 may be more easily formed when the first substrate 300 is a P-type substrate. For example, by placing the first substrate 300 in an HF solution, electrochemical etching (i.e., electrolysis) of the first substrate 300 occurs under an anodic bias, so that the amorphous silicon structure 301 can be formed, and by controlling the process conditions such as the concentration of the HF solution and the current density, the pore size in the amorphous silicon structure 301 can also be controlled.

Subsequently, step S3 is performed, and as shown in fig. 3B, a protective layer 302 covering the amorphous silicon structure 301 is formed on the first surface of the first substrate 300. Illustratively, the material of the protective layer 302 may include ethyl silicate (TEOS). Other oxides may be used for the material of the protective layer 302. The protective layer 302 serves to isolate and protect the amorphous silicon structure 301.

Illustratively, after forming the protective layer 302, a first bond metal ring structure 303 is formed on the second surface of the first substrate 300. Specifically, as shown in fig. 3C, the step of forming the first bond metal ring structure 303 may specifically include:

first, a metal material layer is deposited on the second surface of the first substrate 300. Next, forming a mask layer, such as a photoresist layer, on the metal material layer; the metal material layer is etched with the mask layer as a mask to form the first bond metal ring structure 303, and then the mask layer is removed.

In some embodiments, the material of the first bond metal ring structure 303 includes a metallic material such as germanium, aluminum, copper, nickel, gold, and the like. In some embodiments, a sputtering or evaporation process may be used to deposit a layer of metallic material on the second surface of the first substrate 300. Then, the metal material layer can be etched by dry etching, reactive Ion Etching (RIE), ion beam etching, plasma etching and other etching processes.

Subsequently, step S4 is performed, as shown in fig. 3D, the second surface of the first substrate 300 is patterned to form the first grooves 304 in the first region and the second grooves 305 in the second region.

In some embodiments, the first groove 304 and the second groove 305 may be formed simultaneously in one patterning process. In one example, the second surface of the first substrate 300 may be patterned to form the first recess 304, and then patterned to form the second recess 305; alternatively, the second surface of the first substrate 300 may be patterned to form the second recess 305, and then patterned to form the first recess 304.

In one example, with continued reference to fig. 3D, the second surface of the first substrate 300 may also be patterned to form a third recess 306 in the first region, the location of the third recess 306 corresponding to the amorphous silicon structure 301. The third groove 306 is used for pumping, and has a width and depth smaller than those of the first groove 304 and the second groove 305. The order of forming the first groove 304, the second groove 305, and the third groove 306 is not fixed, and the third groove 306 and the first groove 304 and the second groove 305 may be formed simultaneously in one patterning process, or the third groove 306 may be formed before or after the first groove 304 and the second groove 305.

In one example, as shown in fig. 3E, after the first groove 304, the second groove 305, and the third groove 306 are formed, the gas absorbing layer 307 may also be formed in the first groove 304. The gas absorbing layer 307 serves to absorb gas, thereby further improving the vacuum degree of the first MEMS device. The gas absorbing layer 307 may be a metal layer, including in particular but not limited to a Ti layer. Illustratively, a thick photoresist process may be used to form a photoresist layer exposing the first recess 304 and to deposit the gas absorbing layer 307 at the bottom of the first recess 304.

Subsequently, step S5 is performed to etch the second surface of the first substrate 300 to form the pumping holes exposing the amorphous silicon structure 301.

Specifically, as shown in fig. 3F, when the second surface of the first substrate 300 is formed with the third groove 306, the third groove 306 of the second surface of the first substrate 300 is etched to form the pumping hole 308, and the amorphous silicon structure 301 is exposed. The third recess 306, the pumping holes 308 and the amorphous silicon structure 301 together form a gas flow path. In other embodiments, the second surface of the first substrate 300 may also be directly etched to form the gas pumping holes communicating with the amorphous silicon structure 301, so that the gas pumping holes and the amorphous silicon structure 301 form a gas flow path.

Subsequently, step S6 is performed to bond the second surface of the first substrate 300 with the first surface of the second substrate 309 to form a first cavity in the first region and a second cavity in the second region. The first cavity is a cavity of the first MEMS device and is used for accommodating the first MEMS structure of the first MEMS device to move in; the first cavity is a cavity of a second MEMS device for receiving a second MEMS structure of the second MEMS device for movement therein.

In one example, as shown in fig. 3G, a second bond metal ring structure 310 is first formed on a first surface of a second substrate 309 prior to bonding. Optionally, forming the second bond metal ring structure 310 may include the steps of: depositing a layer of metal material on a first surface of a second substrate 309; forming a mask layer, such as a photoresist layer, on the metal material layer; the metal material layer is etched using the mask layer as a mask to form the second bond metal ring structure 310, and then the mask layer is removed.

In some embodiments, the material of the second bond metal ring structure 310 includes a metallic material such as germanium, aluminum, copper, nickel, gold, and the like. In some embodiments, a sputtering or evaporation process may be used to deposit a layer of metallic material on the first surface of the second substrate 309. In this step, dry etching, reactive Ion Etching (RIE), ion beam etching, plasma etching, or the like may be selected.

In one example, as shown in fig. 3H, the second surface of the first substrate 300 is bonded to the first surface of the second substrate 309, specifically, the first bond metal ring structure 303 of the first substrate 300 is metal bonded to the second bond metal ring structure 310 of the second substrate 309.

Subsequently, step S7 is performed, and as shown in fig. 3H, the protective layer 302 is etched to expose the amorphous silicon structure 301. In this step, a dry etching, a Reactive Ion Etching (RIE), an ion beam etching, a plasma etching, or the like may be selected to remove a portion of the protective layer over the amorphous silicon structure 301 to expose the amorphous silicon structure 301.

Finally, step S8 is performed to pump the first cavity through the amorphous silicon structure 301 and the pump-down holes 308, as shown in fig. 3I, and step S9 is performed to deposit a metal layer 311 over the amorphous silicon structure 301 and the protection layer 302. The metal layer 311 is used to encapsulate the amorphous silicon structure 301. Because the amorphous silicon structure 301 is a solid structure and has a relatively flat surface, the amorphous silicon structure 301 can be covered and sealed by directly depositing the metal layer 311, thereby solving the problem of filling and sealing the pumping holes with larger size.

Specifically, the process of depositing the metal layer 311 includes a process having a vacuum requirement such as a physical vapor deposition or evaporation process. Before the physical vapor deposition or evaporation process is performed, the chamber needs to be vacuumized firstly, in the step, because the first cavity is communicated with the outside through the amorphous silicon structure 301 and the air suction holes 308, the air in the first cavity can be pumped in the vacuumizing process, and the vacuum degree of the first cavity is improved; the second cavity is not communicated with the outside, so that the vacuumizing step does not influence the vacuum degree of the second cavity. Thus, the first MEMS device and the second MEMS device formed on the same substrate can be made to have different vacuum degrees. The process of depositing the metal layer 311 is then also performed in the same vacuum chamber, so that the first cavity remains at a higher vacuum level after the metal layer 311 is deposited.

It should be noted that the first substrate in the method for manufacturing the MEMS device described with reference to fig. 3A to 3I is a P-type substrate. In another embodiment, the first substrate may also be an N-type substrate, and a method of processing the first substrate of the MEMS device of the present invention will be described in detail with reference to fig. 4A to 4F. Fig. 4A-4F are schematic cross-sectional views of a device obtained by sequentially processing a first substrate of a MEMS device according to another embodiment of the present invention, wherein the first substrate is an N-type substrate.

Specifically, as shown in fig. 4A, a first substrate 400 is provided, and a first surface of the first substrate 400 is etched to form a deep groove. In this embodiment, the first substrate 400 is an N-type substrate.

And then, forming a P-type semiconductor material in the deep groove. Specifically, as shown in fig. 4B, first, a P-type semiconductor material 401 is formed above the first surface of the first substrate 400 and in the deep trench, and then, a planarization process is performed to remove the P-type semiconductor material outside the deep trench, and the P-type semiconductor material in the deep trench is retained, so that the surface of the P-type semiconductor material and the first surface of the first substrate 400.

Next, as shown in fig. 4C, an amorphous silicon structure 402 is formed in the deep trench, optionally comprising the steps of: forming a mask layer, such as a photoresist layer, on a first surface of the first substrate 400; the P-type semiconductor material 401 is etched using the mask layer as a mask using a porous silicon etch process to form an amorphous silicon structure 402. Because the difficulty of executing the porous silicon etching process on the N-type substrate is high, the embodiment firstly forms the deep groove in the N-type substrate, then fills the P-type semiconductor material in the deep groove, and then etches the P-type semiconductor material by adopting the porous silicon etching process to form the amorphous silicon structure, thereby reducing the difficulty of forming the amorphous silicon structure.

Next, as shown in fig. 4D, a protective layer 403 is formed on the first surface of the first substrate 400 to cover the amorphous silicon structure 402. Illustratively, the material of protective layer 403 may include ethyl silicate (TEOS). Other oxides may be used as the material of the protective layer 403. The protective layer 403 is used to isolate and protect the amorphous silicon structure 402.

Next, as shown in fig. 4E, a first bond metal ring structure 404 is formed on the second surface of the first substrate 400. Specifically, a metal material layer is deposited on the second surface of the first substrate 400; forming a mask layer, such as a photoresist layer, on the metal material layer; the metal material layer is etched using the mask layer as a mask to form the first bond metal ring structure 404, and then the mask layer is removed.

Next, as shown in fig. 4F, the second surface of the first substrate 400 is patterned, forming a first recess 405, a second recess 406, and a third recess 407. The first recess 405 is used to form a cavity of a first MEMS device, the second recess 406 is used to form a cavity of a second MEMS device, and the third recess 407 is used to form a gas flow path together with the amorphous silicon structure 402, thereby evacuating the cavity of the first MEMS device. The subsequent process is the same as that when the first substrate is a P-type substrate, and specific reference may be made to the above, and details are not repeated here.

The key steps of the method for manufacturing the MEMS device of the present invention are described so far, and other steps may be included in the preparation of the complete MEMS device, which will not be described in detail herein. It should be noted that the above steps are merely examples, and the order of the steps may be adjusted without conflict.

In summary, the manufacturing method of the MEMS device of the embodiment of the present invention can form an amorphous silicon structure for pumping the first cavity, thereby improving the vacuum degree of the first cavity and solving the problem of filling and sealing of the pumping hole with a larger size.

Example two

The invention also provides a MEMS device prepared by the method in the first embodiment. Specifically, the MEMS device comprises a first substrate and a second substrate which are bonded together, wherein the first substrate comprises a first area and a second area, a first cavity is formed in the first area, a second cavity is formed in the second area, an amorphous silicon structure and an air pumping hole are formed in the first area, a protective layer and a metal layer for sealing the amorphous silicon structure are sequentially deposited on the first substrate, and a gas absorbing layer can be formed in the first cavity; a first MEMS structure and a second MEMS structure are integrated on the second substrate, the first MEMS structure is located in the first cavity, and the second MEMS structure is located in the second cavity. Illustratively, the first MEMS device may be a gyroscope, the second MEMS device may be an accelerometer, and the first MEMS structure may be a comb structure of the gyroscope, and the second MEMS structure may be a comb structure of the accelerometer. Other constituent structures may also be included in the complete MEMS device, and are not described in detail herein.

Because the MEMS device provided by the embodiment of the invention is provided with the amorphous silicon structure to pump air out of the first cavity, the vacuum degree of the first cavity is improved, the filling and sealing problem of the air pumping holes with larger size is solved, the cost is further reduced, and the efficiency is improved.

Although a number of embodiments have been described herein, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. More particularly, various modifications and alterations may be made in the arrangement and/or component parts of the subject matter within the scope of the disclosure, the drawings, and the appended claims. In addition to modifications and variations in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.

Claims

1. A method of manufacturing a MEMS device, the method comprising:

etching the protective layer to expose the amorphous silicon structure;

2. The method of manufacturing of claim 1, wherein the first substrate is a P-type substrate, and the forming an amorphous silicon structure in the first region of the first surface of the first substrate comprises:

and corroding the first surface of the P-type substrate by adopting a porous silicon corrosion process to form the amorphous silicon structure.

3. The method of manufacturing of claim 1, wherein the first substrate is an N-type substrate, and the forming an amorphous silicon structure in the first region of the first surface of the first substrate comprises:

etching a deep groove on the first surface of the N-type substrate;

forming a P-type semiconductor material in the deep groove;

and corroding the P-type semiconductor material by adopting a porous silicon corrosion process to form the amorphous silicon structure.

4. The method of manufacturing of claim 1, further comprising, prior to etching the second surface of the first substrate to form a pumping hole exposing the amorphous silicon structure:

patterning the second surface of the first substrate to form a third groove in the first region, wherein the position of the third groove corresponds to the amorphous silicon structure;

the air pumping hole is positioned in the third groove.

5. The method of manufacturing according to claim 1, wherein prior to forming the bleed holes, the method further comprises:

a gas absorbing layer is formed in the first recess.

6. The method of manufacturing according to claim 1, wherein the material of the protective layer comprises ethyl silicate.

7. The method of manufacturing of claim 1, wherein prior to patterning the second surface of the first substrate, the method further comprises:

and forming a first bond metal ring structure on the second surface of the first substrate.

8. The method of manufacturing of claim 7, wherein prior to bonding the second surface of the first substrate to the first surface of the second substrate, the method further comprises:

forming a second bond metal ring structure on the first surface of the second substrate;

the bonding the second surface of the first substrate to the first surface of the second substrate includes: and carrying out metal bonding on the first bonding metal ring structure and the second bonding metal ring structure.

9. The method of any of claims 1-8, wherein the first MEMS structure comprises a comb structure of a gyroscope and the second MEMS structure comprises a comb structure of an accelerometer.

10. A MEMS device, characterized in that it is manufactured by the method according to any of claims 1-9.