CN113912000A

CN113912000A - Micromechanical structure and method of fabrication

Info

Publication number: CN113912000A
Application number: CN202111327657.5A
Authority: CN
Inventors: 赵成龙; 何政达; 万蔡辛; 蒋樱
Original assignee: Wuxi Weigan Semiconductor Co ltd
Current assignee: Wuxi Weigan Semiconductor Co ltd
Priority date: 2021-11-10
Filing date: 2021-11-10
Publication date: 2022-01-11

Abstract

The application discloses a micro-mechanical structure and a manufacturing method thereof, wherein the micro-mechanical structure comprises a substrate, a first sacrificial layer and a main structure layer, the first sacrificial layer is positioned on the substrate, the main structure layer is positioned on the first sacrificial layer, and a first cavity is formed in the first sacrificial layer; the main structure layer comprises a release window penetrating through the upper surface and the lower surface of the main structure layer and a blocking structure positioned in the release window; the first cavity enables at least part of the main structure layer to be suspended, the blocking structure enables the first cavity to be sealed, the release window is blocked, the completeness of the surface of the vibration film in a specific range is achieved, the sealing performance of the first cavity is guaranteed, furthermore, the blocking structure can form a protrusion on the main structure layer, the main structure layer can be prevented from being adhered to an adjacent structure in the deformation or movement process through the small protrusion, and the possibility that a device fails due to adhesion is reduced.

Description

Micromechanical structure and method of fabrication

Technical Field

The invention relates to the technical field of microelectronic devices, in particular to a micro-mechanical structure and a manufacturing method thereof.

Background

Micro-Electro-Mechanical systems (MEMS) which generally comprise micromechanical structures to perform specific functions. MEMS generally include a sacrificial layer and a structural layer, and a release cavity is formed below the structural layer by etching the sacrificial layer (also called release), so that part of the structural layer is suspended to form a movable structure. Generally, for surface processing or releasing of a type of alternately stacking a structural layer and a sacrificial layer, the release is mainly corrosion-advanced along the plane direction of the sacrificial layer, and in order to shorten the release length and smoothly realize the structure release, a plurality of and dispersed release windows penetrating through the upper and lower surfaces of the structural layer are usually required to be arranged on the structural layer for the etchant to enter.

However, the release window on the structural layer destroys the integrity of the structural layer, and the release window connects the release cavity with the outside, so that specific air pressure or gas atmosphere in the release cavity cannot be kept, further, when the structural layer floats up and down, the structural layer may be adhered to an adjacent structure, so that the structural layer cannot move normally, and the device fails.

Therefore, it is desirable to design a micromechanical structure to improve the integrity of the structural layer and reduce the risk of adhesion between the structural layer and the adjacent structure.

Disclosure of Invention

The invention aims to provide a micro-mechanical structure and a manufacturing method thereof, and aims to solve the problems that in the prior art, a product is adhered to an adjacent structure to cause device failure, specific requirements cannot be met and the like. The integrity and the reliability of the micro-mechanical mechanism are improved, specific air pressure or gas atmosphere can be kept in the release cavity, the use scene is expanded, the production cost is reduced, and the production efficiency is improved.

According to an aspect of the present invention, there is provided a micromechanical structure, characterized by comprising: a substrate; the first sacrificial layer is positioned on the substrate, and a first cavity is formed in the first sacrificial layer; the main structure layer is positioned on the first sacrificial layer and comprises a release window penetrating through the upper surface and the lower surface of the main structure layer and a blocking structure positioned in the release window; wherein the first cavity suspends at least part of the main structure layer, and the blocking structure seals the first cavity.

Preferably, the blocking structure forms a protrusion on at least one side of the release window.

Preferably, the side wall of the release window has a preset inclination angle, and the opening on the upper surface of the release window is larger than the opening on the lower surface of the release window.

Preferably, the first cavity comprises a gas under pressure.

Preferably, the substrate further comprises a pit connected with the first cavity to increase the volume of the first cavity.

Preferably, the blocking structure has a specific weight, the blocking structure doubles as a counterweight of the main structure layer, and the vibration performance of the main structure layer is adjusted by adjusting the weight of the blocking structure.

Preferably, the material of the first sacrificial layer comprises at least one of an oxide of silicon or phosphosilicate glass.

Preferably, the main structure layer comprises at least one of polycrystalline silicon, monocrystalline silicon, amorphous silicon and silicon nitride.

Preferably, the first cavity is formed by etching the first sacrificial layer through a release window on the main structure layer, and the etching process of the first sacrificial layer includes at least one of wet etching using a buffered oxide etchant and vapor dry etching using hydrofluoric acid.

Preferably, the blocking structure comprises silicon nitride, the blocking structure being formed by chemical vapor deposition.

Preferably, the blocking structure is formed by plasma enhanced chemical vapor deposition, and the blocking structure further includes a protrusion formed on a lower surface of the release window.

Preferably, the blocking structure is formed by low pressure chemical vapor deposition, and the blocking structure further comprises a sealing layer covering the inner surface of the first cavity.

Preferably, the micromechanical structure further comprises: the second sacrificial layer and the first structural layer are located between the substrate and the main structural layer, the first structural layer is located on the second sacrificial layer, a second cavity is formed in the second sacrificial layer, and at least part of the first structural layer can float up and down.

Preferably, a third sacrificial layer and a second structural layer are further formed on the main structural layer, a third cavity is formed in the third sacrificial layer, the third cavity is located between the second structural layer and the main structural layer, and at least part of the second structural layer can float up and down.

Preferably, the micromechanical structure is used in a MEMS chip.

According to another aspect of the present invention, there is also provided a method for fabricating a micromechanical structure, including: forming a first sacrificial layer and a main structure layer on a substrate; forming a release window on the main structure layer, etching the first sacrificial layer through the release window to form a first cavity in the first sacrificial layer, wherein at least part of the main structure layer is suspended by the first cavity; depositing a plugging material on the main structure layer, wherein part of the plugging material enters the release window to plug the release window; retaining the plugging structure for plugging the release window, and removing the remaining plugging material; wherein the blocking structure seals the first cavity.

Preferably, the step of depositing the plugging material on the primary structural layer is performed in a specific pressure or gas atmosphere, so that a certain pressure or gas atmosphere exists in the sealed release cavity.

Preferably, before forming the first sacrificial layer and the main structure layer on the substrate, further comprising: etching a pit on a substrate, and depositing a material of a first sacrificial layer in the pit; when the first sacrificial layer is etched through the release window, the material of the first sacrificial layer in the pit is also removed, and the volume of the first cavity is increased through the pit.

Preferably, before forming the first sacrificial layer and the main structure layer on the substrate, further comprising: forming a second sacrificial layer and a first structural layer on a substrate; forming a release window on the first structure layer, etching the second sacrificial layer through the release window to form a second cavity in the second sacrificial layer, wherein at least part of the first structure layer is suspended by the second cavity; when a first sacrificial layer and a main structural layer are formed on a substrate, the first sacrificial layer is located on the first structural layer.

Preferably, the method further comprises: and processing the plugging structure to reduce the area of the top surface of the plugging structure.

Preferably, after the treatment, the method further comprises: forming a third sacrificial layer and a second structural layer on the main structural layer; and forming a release window penetrating through the upper surface and the lower surface of the second structure layer, etching the third sacrificial layer through the release window to form a third cavity, and suspending at least part of the second structure layer by the third cavity to form a movable structure positioned on the main structure layer.

Preferably, the material of the first sacrificial layer comprises at least one of silicon oxide or phosphosilicate glass, and the main structure layer comprises at least one of polysilicon, monocrystalline silicon, amorphous silicon and silicon nitride.

Preferably, the etching process of the first sacrificial layer includes at least one of wet etching using a buffered oxide etchant and vapor dry etching using hydrofluoric acid.

Preferably, the blocking structure comprises silicon nitride, and the blocking material is formed on the main structure layer by chemical vapor deposition.

According to the micromechanical structure and the manufacturing method provided by the embodiment of the invention, the release window is plugged, so that the integrity of the surface of the vibrating membrane in a specific range is realized, the sealing property of the first cavity is ensured, a certain pressure or gas atmosphere can be kept in the first cavity to meet specific requirements, and specific device functions are realized; furthermore, the blocking structure also has a specific weight and can be used as a counterweight to adjust the vibration performance of the main structure layer, and the blocking structure also can comprise a sealing layer covering the inner surface of the first cavity, so that the sealing effect of the cavity is enhanced; the sizes of the first cavity and the release window can be adjusted according to actual requirements, and the main structural layer after the release window is plugged has better integrity and certain waterproof performance.

The manufacturing method of the packaging structure provided by the embodiment of the invention has the advantages that the related processing technology is mature and reliable, the method is simple and convenient to realize, the anti-adhesion protrusions can be formed on the upper side and/or the lower side of the main structure layer through simple treatment, the sealing layer covering the inner surface of the first cavity can be formed through chemical vapor deposition, the sealing effect of the cavity is enhanced, the manufacturing method can meet various requirements, the technology is simple, and the production efficiency is high.

Drawings

The above and other objects, features and advantages of the present invention will become more apparent from the following description of the embodiments of the present invention with reference to the accompanying drawings.

Fig. 1 shows a schematic view of a micromechanical structure according to a first embodiment of the present invention;

FIG. 2 is a schematic diagram illustrating a fabrication process of a micromechanical structure according to the present invention;

figures 3-6 show schematic views of stages in the fabrication of a micromechanical structure according to a first embodiment of the present invention;

fig. 7 shows a schematic view of a micromechanical structure according to a second embodiment of the present invention;

figure 8 shows a schematic view of a process for fabricating a micromechanical structure according to a third embodiment of the present invention;

fig. 9 shows a schematic diagram of a process for fabricating a micromechanical structure according to a fourth embodiment of the present invention;

figures 10-13 show schematic diagrams of stages in the fabrication of a micromechanical structure according to a fifth embodiment of the present invention;

figure 14 shows a schematic view of a micromechanical structure according to a sixth embodiment of the invention;

fig. 15a-15c show schematic views of micromechanical structures according to seventh, eighth and ninth embodiments of the present invention, respectively.

Detailed Description

The invention will be described in more detail below with reference to the accompanying drawings. Like elements in the various figures are denoted by like reference numerals. For purposes of clarity, the various features in the drawings are not necessarily drawn to scale. In addition, certain well known components may not be shown. For simplicity, the semiconductor structure obtained after several steps can be described in one figure.

It will be understood that when a layer or region is referred to as being "on" or "over" another layer or region in describing a structure, it can be directly on the other layer or region or intervening layers or regions may also be present. And, if the device is turned over, that layer, region, or regions would be "under" or "beneath" another layer, region, or regions.

If for the purpose of describing the situation directly on another layer, another area, the expression "directly on … …" or "on … … and adjacent thereto" will be used herein.

In the following description, numerous specific details of some embodiments of the invention, such as structure, materials, dimensions, processing techniques and techniques of the devices are described to provide a more thorough understanding of the invention. However, as will be understood by those skilled in the art, the present invention may be practiced without these specific details.

The present invention may be embodied in various forms, some examples of which are described below.

Fig. 1 shows a schematic view of a micromechanical structure according to a first embodiment of the present invention, in which the micromechanical structure comprises: the structure comprises a substrate 110, a first sacrificial layer 120 and a main structure layer 130, wherein the first sacrificial layer 120 is located on the substrate 110, the main structure layer 130 is located on the first sacrificial layer 120, the first sacrificial layer 120 comprises a first cavity 121 located below the main structure layer 130, the main structure layer 130 comprises a release window 131, the first cavity 121 is communicated with the outside through the release window 131, and the first cavity 121 is formed by etching the first sacrificial layer 120 through the release window 131. The side wall of the release window 131 is obliquely arranged, so that the size of the upper opening of the release window 131 is larger than that of the lower opening of the release window, the inclination angle of the side wall can be adjusted according to the size of the release window 131, and the like, to ensure that the release window 131 can be fully filled and has no gap by the blocking structure 141, and to ensure the sealing property of the first cavity 121 after the blocking structure 141 fills the release window 131, the blocking structure 141 is only a part of a blocking layer, for example, the blocking layer is arranged on the main structure layer 130, and the blocking structure 141 in the area of the release window 131 is reserved by etching the blocking layer, thereby realizing the structure shown in fig. 1. Specifically, after the deposition of the blocking layer, dry etching is performed on the entire blocking layer, and in combination with the monitoring of the etching end point, only the blocking layer on the surface of the main structure layer 130 is removed, and the blocking structure 141 in the release window 131 is retained, so that the first cavity 121 is sealed, and the integrity of the micromechanical structure is improved.

Fig. 2 is a schematic diagram of a manufacturing process of a micro-mechanical structure according to the present invention, fig. 3 to 6 are schematic diagrams of stages in a manufacturing process of a micro-mechanical structure according to a first embodiment of the present invention, fig. 7 is a schematic diagram of a micro-mechanical structure according to a second embodiment of the present invention, and the manufacturing process of the mechanical structure will be described with reference to fig. 3 to 7.

The manufacturing process of the micro mechanical structure comprises the following steps:

in step S10: forming a first sacrificial layer 120 and a main structure layer 130 on a substrate 110; this step corresponds to fig. 3, in which the substrate 110 is made of, for example, monocrystalline silicon or polycrystalline silicon, the first sacrificial layer 120 is made of, for example, silicon oxide or phosphorosilicate glass, since a part of the main structure layer 130 is finally used as a movable part capable of freely deforming, and the main structure layer 130 is, for example, a composite layer made of one or more materials of polycrystalline silicon, monocrystalline silicon, amorphous silicon, and silicon nitride, so as to enhance the mechanical properties of the main structure layer 130 and meet the use requirements. Of course, the micro-mechanical structure may also be fabricated on the basis of other adjacent structures, and the substrate 110 is replaced with other adjacent structures without a sacrificial layer, and the micro-mechanical structure may be fabricated on the basis of other adjacent structures.

In step S20: forming a release window 131 in the main structure layer 130, etching the first sacrificial layer 120 through the release window 131 to form a first cavity 121 in the first sacrificial layer 120, so that at least a partial region of the main structure layer 130 is suspended; this step corresponds to fig. 4, for example, the release window 131 penetrates through the upper and lower surfaces of the main structure layer 130, the sidewall of the release window 131 is designed to be inclined, for example, the inclination angle is adjusted according to the actual situation, mainly considering that when the subsequent deposition of the plugging material is performed, the release window 131 is filled up without a gap, and the release window area is as flat as possible. The first sacrificial layer 120 under the main structure layer 130 is etched through the release window 131 to form a first cavity 121, so that at least a part of the main structure layer 130 is suspended and can be freely deformed to form movable mechanical structures such as a diaphragm. The first sacrificial layer 120 is etched, for example, by wet etching using a buffered oxide etching solution or vapor etching using hydrofluoric acid.

In step S30: depositing a plugging material 140 on the main structure layer 130, wherein part of the plugging material 140 enters the release window 131 to plug the release window 131; this step corresponds to fig. 5, the plugging material 140 is deposited on the main structure layer 130 and covers the main structure layer 130, the release window 131 is plugged, and a part of the plugging material 140 enters the release window 131 to form a plugging structure 141. The blocking material is a thin film formed of silicon oxynitride, nitride, or the like, and is deposited on the main structure layer 130 by chemical vapor deposition.

Of course, the release window 131 may also be sealed under a certain pressure or gas atmosphere by adjusting the process parameters of the chemical vapor deposition, so that the sealed first cavity 121 has a certain pressure or gas atmosphere, thereby obtaining different properties to meet specific requirements.

In step S40: retaining the plugging structure for plugging the release window, and removing the plugging material of the rest part; the removing process can adopt the whole surface etching matched with the end point monitoring or adopts the photoetching mode to carry out etching after defining an etching area; the two processes correspond to fig. 6 and fig. 7, respectively.

As shown in fig. 6, the plugging material 140 enters the release window 131 and plugs the release window 131, and the thickness of the plugging material 140 at this position is significantly greater than the thickness of the plugging material 140 at other areas on the main structure layer 130, so the method of full-surface dry etching may be adopted to etch the plugging material 140 on the main structure layer 130, and perform etching end point monitoring, and after the plugging material 140 on the main structure layer 130 is removed, the etching is terminated, so that the plugging structure 141 in the release window 131 is retained, and although the upper surface of the plugging structure 141 is etched to form a concave shape, the plugging to the release window 131 and the sealing performance of plugging are not affected.

Further, as shown in fig. 7, the blocking material 140 may also be etched by using a photolithography process to define the release window 131 and the pattern of the surrounding area, the blocking material 140 in the area is completely retained in the etching process, the blocking material 140 in other areas is removed, and the etching is stopped on the surface of the main structure layer 130, because the etching area is divided, the blocking material 140 in the release window 131 and the surrounding area is retained, and the blocking structure 141 filled in the release window 131 and the bump 142 above the blocking structure 141 are retained. Preferably, the blocking structure 141 and the bump 142 may also serve as a weight of the main structure layer 130, and the weight of the weight is changed by adjusting the thickness of the etching reserved area or the blocking material 140, so as to adjust the vibration characteristic of the main structure layer 130.

Fig. 8 and 9 show schematic diagrams of micromechanical structures according to third and fourth embodiments of the present invention during their fabrication, respectively; fig. 8 and 9 correspond to step S30.

Specifically, as shown in fig. 8, a blocking material 140 is deposited on the main structure layer 130 and covers the main structure layer 130, the release window 131 is blocked, and a part of the blocking material 140 enters the release window 131 to form a blocking structure 141. The blocking material 140 is, for example, a thin film formed of silicon oxynitride, nitride, or the like, and the release window sealing is realized by a growth method of Plasma Enhanced Chemical Vapor Deposition (PECVD); further, the plugging material 140 partially overflows the release windows 131 to form protrusions 143 at the lower ends of the release windows 131; and at the same time, forming protrusions 144 corresponding to the protrusions 143 on the bottom surface of the first cavity 121 (the upper surface of the substrate 110), the above-mentioned protrusion structure can prevent the main structure layer 130 from adhering to the adjacent structure during deformation or movement,

similarly, if the blocking material 140 is deposited (grown) by Low Pressure Chemical Vapor Deposition (LPCVD), the structure shown in fig. 9 can be formed, and the blocking material 140 not only forms the blocking structure 141 for blocking the release window, but also the blocking material 140 enters the first cavity 121 before the release window is blocked, and forms the sealing layer 145 covering all surfaces inside the first cavity 121, so as to further enhance the cavity sealing effect.

The step S40 of fabricating the micromechanical structures according to the third and fourth embodiments corresponding to fig. 8 and 9 is similar to that of the first embodiment, and therefore, the description is omitted here, and the final structural illustration is omitted.

Figures 10-13 show schematic diagrams of stages in the fabrication of a micromechanical structure according to a fifth embodiment of the present invention; most of the structure and the processing process are similar to those of the first embodiment, and are not repeated herein, but the difference is that compared with the first embodiment, the fifth embodiment pre-sets a groove 211 on the substrate 210, the groove 211 is formed by, for example, etching, the same material as the first sacrificial layer 220 is deposited in the groove 211, the sacrificial layer material is thinned and ground to the surface of the substrate 210 by using a chemical mechanical polishing process, so that the entire surface is planarized, the first sacrificial layer 220 is deposited thereon, and the main structure layer 230 is formed on the first sacrificial layer 220, optionally, the thickness of the first sacrificial layer 220 is greater than the depth of the groove 211. When the first sacrificial layer 220 is etched, the filling material in the groove 211 is also removed together, and the groove 211 is communicated with the first cavity 221, so that the volume of the cavity is further increased to meet the working requirement of a specific device.

Figure 14 shows a schematic view of a micromechanical structure according to a sixth embodiment of the invention; most of the structure and the processing process of the sixth embodiment are similar to those of the second embodiment, and are not repeated herein, but the difference is that compared with the second embodiment, the sixth embodiment forms a groove 211 on the substrate 210 in advance, and the groove 211 is communicated with the first cavity 221, so that the cavity volume can be further increased, and the requirements of more use scenarios can be met.

Fig. 15a-15c show schematic views of micromechanical structures according to seventh, eighth and ninth embodiments of the present invention, respectively. In the seventh embodiment shown in fig. 15a, compared with the fifth embodiment shown in fig. 13, a second sacrificial layer 322 and a first structural layer 341 are additionally arranged between the substrate 310 and the main structural layer 330, the first structural layer 341 has an unblocked release window 343, the second sacrificial layer 322 also has a second cavity 325, the second cavity 325 is communicated with the first cavity 324 through the release window 343, and the recess 311 is connected with the second cavity 325; further, a third sacrificial layer 323 and a second structural layer 342 are also added above the main structural layer 330, the second structural layer 342 has an unblocked release window 344, and the third sacrificial layer 323 has a third cavity 326 therein, so that the second structural layer 342 is at least partially suspended. The eighth embodiment shown in fig. 15b is also similar to the sixth embodiment shown in fig. 14, and is not repeated, and the ninth embodiment shown in fig. 15c is based on the eighth embodiment, before the third sacrificial layer 323 and the second structural layer 342 are formed on the main structural layer 330, the bump 332 above the blocking structure 331 on the main structural layer 330 is trimmed by using a photolithography process, so as to reduce the area of the top of the bump 332, so that a convex hull shape is formed at the top of the bump 332, and the area of the top of the bump 332 is reduced, so that the bump 332 is prevented from being adhered to the second structural layer 342 when the main structural layer 330 floats upwards. The micromechanical mechanisms of the seventh, eighth, and ninth embodiments will be described in detail below with reference to fig. 15a to 15c, respectively.

Specifically, as shown in fig. 15a, the micro-mechanical structure sequentially includes, from bottom to top, a substrate 310, a second sacrificial layer 322, a first structure layer 341, a first sacrificial layer 321, a main structure layer 330, a blocking structure 331, a third sacrificial layer 323, and a second structure layer 342, where a second cavity 325 is provided between the first structure layer 341 and the substrate 310, a first cavity 324 is provided between the main structure layer 330 and the first structure layer 341, and a third cavity 326 is provided between the second structure layer 342 and the main structure layer 330; the substrate 310 is provided with a recess 311, the recess 311 is communicated with the second cavity 325, the first structural layer 341 is further provided with a release window 343 penetrating through the upper and lower surfaces thereof, and the second cavity 325 is communicated with the first cavity 324 through the release window 343. The main structure layer 330 also has a release window, the side wall of the release window is, for example, an inclined surface, forming a release window with a large top and a small bottom, the release window is blocked by a blocking structure 331, so as to isolate the first cavity 324 from the third cavity 326, the second structure layer 342 also has a release window 344, and the third cavity 326 is communicated with the outside through the release window 344. Fig. 15a shows a blocking structure 331 in a main structure layer 330, for example, similar to that in fig. 6, the upper surface of the blocking structure 331 is etched to be concave, but the sealing performance of the blocking structure is not affected. Of course, it is also possible to form a protrusion under the blocking structure 331 or to form a sealing layer covering the inner surface of the first cavity 324 (and the second cavity 325) in the manner shown in fig. 8 or 9.

In the manufacturing process of the micro-mechanical structure shown in fig. 15a, the structure formed by the substrate 310, the second sacrificial layer 322, and the first structure layer 341 may be manufactured in advance by using the existing technology and scheme, then the first sacrificial layer 321, the main structure layer 330, and the blocking structure 331 are manufactured on the basis of the structure, and finally the third sacrificial layer 323 and the second structure layer 342 are manufactured on the main structure layer 330, so that the micro-mechanical structure shown in fig. 15a may be obtained finally, and the specific steps and processes of etching and depositing and the like are not repeated, and certainly, the first cavity 324 and the second cavity 325 may further include a pre-filled gas with a certain pressure and sealed by the blocking structure 331.

The blocking structure 331 in fig. 15b is similar to that in fig. 7, and is formed by, for example, a photolithography process, and a bump 332 is remained above the blocking structure 331.

Fig. 15c is similar to fig. 15b, in which, before the third sacrificial layer 323 and the second structural layer 342 are formed, the bump 332 above the blocking structure 331 is processed by a photolithography process on the basis of fig. 15b, so as to reduce the area of the upper surface of the bump, so that the top of the blocking structure 331 is formed in a convex shape, and the bump 332 is prevented from being adhered to the subsequently formed second structural layer 342 when the main structural layer 330 floats upwards.

In the above description, the technical details of patterning, etching, and the like of each device are not described in detail. It will be appreciated by those skilled in the art that layers, regions, etc. of the desired shape may be formed by various technical means. In addition, in order to form the same structure, those skilled in the art can also design a method which is not exactly the same as the method described above. In addition, although the embodiments are described separately above, this does not mean that the measures in the embodiments cannot be used in advantageous combination.

The embodiments of the present invention have been described above. However, these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. The scope of the invention is defined by the appended claims and equivalents thereof. Various alternatives and modifications can be devised by those skilled in the art without departing from the scope of the invention, and these alternatives and modifications are intended to fall within the scope of the invention.

Claims

1. A micromechanical structure, comprising:

a substrate;

the first sacrificial layer is positioned on the substrate, and a first cavity is formed in the first sacrificial layer;

the main structure layer is positioned on the first sacrificial layer and comprises a release window penetrating through the upper surface and the lower surface of the main structure layer and a blocking structure positioned in the release window;

wherein the first cavity suspends at least part of the main structure layer, and the blocking structure seals the first cavity.

2. A micromechanical structure according to claim 1, characterized in that the blocking structure forms a protrusion on at least one side of the release window.

3. The micromechanical structure of claim 1, wherein the sidewalls of the release window have a predetermined tilt angle, and an upper surface opening of the release window is larger than a lower surface opening thereof.

4. The micromechanical structure of claim 1, wherein the first cavity includes a gas having a pressure therein.

5. The package structure of claim 1, wherein the substrate further comprises a recess coupled to the first cavity to increase a volume of the first cavity.

6. The package structure of claim 1, wherein the blocking structure has a specific weight, and the blocking structure doubles as a weight of the main structure layer, and the vibration performance of the main structure layer is adjusted by adjusting the weight of the blocking structure.

7. The micromechanical structure of claim 1, wherein the material of the first sacrificial layer comprises at least one of an oxide of silicon or a phosphosilicate glass.

8. The micromechanical structure of claim 1, wherein the main structure layer comprises at least one of polysilicon, single crystal silicon, amorphous silicon, silicon nitride.

9. The micromechanical structure of claim 1, wherein the first cavity is formed by etching the first sacrificial layer through a release window on the main structure layer, and the etching process of the first sacrificial layer comprises at least one of wet etching using a buffered oxide etchant and vapor dry etching using hydrofluoric acid.

10. A micromechanical structure according to claim 1, characterized in that the blocking structure comprises silicon nitride, which blocking structure is formed by chemical vapor deposition.

11. The micromechanical structure of claim 10, wherein the blocking structure is formed by plasma enhanced chemical vapor deposition, the blocking structure further comprising a protrusion formed on a lower surface of the release window.

12. The micromechanical structure of claim 10, wherein the blocking structure is formed by low pressure chemical vapor deposition, the blocking structure further comprising a sealing layer covering an inner surface of the first cavity.

13. The micromechanical structure of claim 1, further comprising: the second sacrificial layer and the first structural layer are located between the substrate and the main structural layer, the first structural layer is located on the second sacrificial layer, a second cavity is formed in the second sacrificial layer, and at least part of the first structural layer can float up and down.

14. The micromechanical structure of claim 13, wherein the main structure layer further has a third sacrificial layer and a second structure layer formed thereon, the third sacrificial layer has a third cavity formed therein, the third cavity is located between the second structure layer and the main structure layer, and at least a portion of the second structure layer is capable of floating up and down.

15. The micromechanical structure of claim 1, wherein the main structure layer further has a third sacrificial layer and a second structure layer formed thereon, the third sacrificial layer has a third cavity formed therein, the third cavity is located between the second structure layer and the main structure layer, and at least a portion of the second structure layer is capable of floating up and down.

16. Micromechanical structure according to claim 1, characterized in that the micromechanical structure is used in a MEMS chip.

17. A method of fabricating a micromechanical structure, comprising:

forming a first sacrificial layer and a main structure layer on a substrate;

forming a release window on the main structure layer, etching the first sacrificial layer through the release window to form a first cavity in the first sacrificial layer, wherein at least part of the main structure layer is suspended by the first cavity;

depositing a plugging material on the main structure layer, wherein part of the plugging material enters the release window to plug the release window;

retaining the plugging structure for plugging the release window, and removing the remaining plugging material;

wherein the blocking structure seals the first cavity.

18. The method of claim 17, wherein the blocking structure forms a protrusion on at least one side of the release window.

19. The method of claim 17, wherein the step of depositing the plugging material on the primary structural layer is performed under a specific pressure or gas atmosphere, such that the sealed release cavity has a certain pressure or gas atmosphere therein.

20. The method of claim 17, wherein the side wall of the release window has a predetermined inclination angle, and the upper surface opening of the release window is larger than the lower surface opening thereof.

21. The method of claim 17, further comprising, prior to forming the first sacrificial layer and the main structure layer on the substrate: etching a pit on a substrate, and depositing a material of a first sacrificial layer in the pit; when the first sacrificial layer is etched through the release window, the material of the first sacrificial layer in the pit is also removed, and the volume of the first cavity is increased through the pit.

22. The method of claim 17, further comprising, prior to forming the first sacrificial layer and the main structure layer on the substrate:

forming a second sacrificial layer and a first structural layer on a substrate;

forming a release window on the first structure layer, etching the second sacrificial layer through the release window to form a second cavity in the second sacrificial layer, wherein at least part of the first structure layer is suspended by the second cavity;

when a first sacrificial layer and a main structural layer are formed on a substrate, the first sacrificial layer is located on the first structural layer.

23. The method of manufacturing of claim 17, further comprising: and processing the plugging structure to reduce the area of the top surface of the plugging structure.

24. The method of making as claimed in claim 23, further comprising after processing said blocking structure:

forming a third sacrificial layer and a second structural layer on the main structural layer;

and forming a release window penetrating through the upper surface and the lower surface of the second structure layer, etching the third sacrificial layer through the release window to form a third cavity, and suspending at least part of the second structure layer by the third cavity to form a movable structure positioned on the main structure layer.

25. The method of claim 17, wherein the material of the first sacrificial layer comprises at least one of silicon oxide or phosphosilicate glass, and the main structural layer comprises at least one of polysilicon, single crystal silicon, amorphous silicon, and silicon nitride.

26. The method of claim 17, wherein the etching process of the first sacrificial layer comprises at least one of wet etching using a buffered oxide etchant and vapor dry etching using hydrofluoric acid.

27. The method of claim 17, wherein the blocking structure comprises silicon nitride, and wherein the blocking material is formed in the main structure layer by chemical vapor deposition.

28. The method of claim 27, wherein the blocking structure is formed by plasma enhanced chemical vapor deposition, the blocking structure further comprising a protrusion formed on a lower surface of the release window.

29. The method of claim 27, wherein the blocking structure is formed by low pressure chemical vapor deposition, the blocking structure further comprising a sealing layer covering an inner surface of the first cavity.