Suspension thermal isolation packaging structure for MEMS devices and method of fabrication

Abstract

The present application relates to a kind of suitable for the suspension heat insulation packaging structure of MEMS device and preparation method.According to the technical scheme provided by the present application, a kind of suitable for the suspension heat insulation packaging structure of MEMS device, the suspension heat insulation packaging structure includes: MEMS device body, including several for the device pad of the MEMS device body leading out;Insulating heat insulation film, cover in the front of MEMS device body, and with the front of the MEMS device body fixed connection, device pad is wrapped in the insulating heat insulation film;Leading out metal unit, including several metal leading out rivets, wherein, metal leading out rivet and device pad are one-to-one correspondence, a metal leading out rivet is connected with the corresponding device pad by the film leading out hole in insulating heat insulation film.Effectively realize the heat insulation packaging of MEMS device by the present application, and effectively realize the leading out of electrical signal under the condition of satisfying heat insulation packaging, safe and reliable.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of suspension heat insulation packaging structure and preparation method, especially a kind of suspension heat insulation packaging structure and preparation method suitable for MEMS device. BACKGROUND

[0002] Micro-Electro-Mechanical System (MEMS), is a multi-disciplinary frontier subject developed on the basis of microelectronics technology, and the micro device prepared has many advantages such as low cost, small size and light weight, so it has been widely used in many fields such as automobile, aerospace, information communication, biochemistry, medical treatment, automatic control and national defense.

[0003] In recent years, with the development of MEMS technology, some new MEMS devices appear, which need to work at a certain temperature. In order to meet the normal work of the device, it needs to maintain a certain temperature when working, which leads to the increase of power consumption of the device. However, low power consumption is the basic requirement of portable, aerospace and other instruments and meters, so the device needs to be heat-insulated packaged.

[0004] The traditional heat insulation packaging methods mainly include the following: 1) using ceramic tube shell packaging with small heat conduction; 2) filling heat insulation layer; 3) vacuum packaging to reduce heat convection. In the heat insulation packaging structure, the heater and temperature sensor need to be assembled independently, which leads to a large overall packaging size. In addition, the traditional heat insulation packaging structure makes it difficult for MEMS devices to lead out electrical signals to realize electrical communication. SUMMARY

[0005] The purpose of the present application is to overcome the shortcomings in the prior art, and to provide a kind of suspension heat insulation packaging structure and preparation method suitable for MEMS device, which can effectively realize the heat insulation packaging of MEMS device, and effectively realize the lead-out of electrical signal under the condition of meeting the heat insulation packaging, safe and reliable.

[0006] According to the technical scheme provided by the present application, a kind of suspension heat insulation packaging structure suitable for MEMS device, the suspension heat insulation packaging structure includes:

[0007] MEMS device body, including a plurality of device pads for leading out the MEMS device body;

[0008] Insulating heat insulation film, covering the front of MEMS device body, and fixedly connected with the front of MEMS device body, and the device pad is wrapped in the insulating heat insulation film;

[0009] The metal lead-out unit comprises a plurality of metal lead-out rivets, wherein the metal lead-out rivets are in one-to-one correspondence with the device pads, and one metal lead-out rivet is electrically connected with the corresponding device pad through a thin-film lead-out hole in the insulating and heat-insulating film.

[0010] The metal lead-out rivet comprises a rivet column filled in the thin-film lead-out hole and a rivet head covering the insulating and heat-insulating film, wherein

[0011] The outer diameter of the rivet head is larger than that of the rivet column, and the rivet head is connected with the corresponding device pad through the rivet column.

[0012] The insulating and heat-insulating film comprises a photoresist layer, a dry film or a light-sensitive adhesive tape, wherein

[0013] When the insulating and heat-insulating film has light sensitivity, the process for preparing the thin-film lead-out hole in the insulating and heat-insulating film comprises photoetching.

[0014] When the insulating and heat-insulating film does not have light sensitivity, the process for preparing the thin-film lead-out hole in the insulating and heat-insulating film comprises laser drilling.

[0015] For the metal lead-out rivet, the process for preparing the rivet column and the rivet head of the metal lead-out rivet comprises electroplating.

[0016] The MEMS device body comprises a device substrate and a back cavity adapted to the MEMS device body, wherein

[0017] The device pad is electrically connected with the device substrate through a metal seed layer;

[0018] The back cavity comprises a substrate hole penetrating through the device substrate and a seed layer hole penetrating through the metal seed layer, the substrate hole and the seed layer hole are in one-to-one correspondence, and the substrate hole and the seed layer hole are in communication.

[0019] A preparation method of a suspended heat-insulating packaging structure suitable for a MEMS device, for preparing the suspended heat-insulating packaging structure, the preparation method comprises the following steps:

[0020] Providing a MEMS device body and preparing a plurality of device pads for leading out the MEMS device body, wherein the device pads are located on the front surface of the MEMS device body;

[0021] Preparing an insulating and heat-insulating film on the above-mentioned MEMS device body, wherein the insulating film covers and is fixedly connected with the front surface of the MEMS device body, and the device pads are wrapped in the insulating and heat-insulating film;

[0022] Preparing a plurality of thin-film lead-out holes in the insulating and heat-insulating film, wherein the thin-film lead-out holes are in one-to-one correspondence with the device pads, and the device pads are exposed through the corresponding thin-film lead-out holes.

[0023] A metal lead unit is fabricated, wherein the metal lead unit includes a plurality of metal lead rivets, each metal lead rivet corresponding one-to-one with a device pad, and each metal lead rivet is electrically connected to the corresponding device pad through a thin film lead hole.

[0024] The insulating and heat-insulating film includes a photoresist layer, a dry film, or a photosensitive tape, wherein,

[0025] When the insulating and heat-insulating film is photosensitive, the process of preparing film lead-out holes in the insulating and heat-insulating film includes photolithography.

[0026] When the insulating and heat-insulating film does not have photosensitivity, the process of preparing film lead-out holes in the insulating and heat-insulating film includes laser drilling.

[0027] For metal lead-out rivets, the manufacturing process of the metal lead-out rivets includes electroplating;

[0028] The metal lead-out rivet includes a rivet post filled in the lead-out hole of the thin film and a rivet cap covering the insulating and heat-insulating film, wherein...

[0029] The outer diameter of the rivet cap is larger than the outer diameter of the rivet post, and the rivet cap is connected to the corresponding component pad through the rivet post.

[0030] The MEMS device body includes a device substrate and a back cavity adapted to the MEMS device body, wherein,

[0031] The device pads are electrically connected to the device substrate via a metal seed layer;

[0032] The back cavity includes a base hole that penetrates the device substrate and a seed layer hole that penetrates the metal seed layer. The base hole and the seed layer hole correspond to each other and are connected.

[0033] The fabrication process of the back cavity includes:

[0034] A cavity mask layer is coated on the back side of the device substrate;

[0035] Selective masking and etching of the cavity mask layer are performed to obtain a cavity mask layer window that penetrates the cavity mask layer;

[0036] The device substrate and the metal seed layer are etched using a cavity mask layer and a cavity mask layer window to obtain a substrate hole that penetrates the device substrate and a seed layer hole that penetrates the metal seed layer, respectively.

[0037] Remove the aforementioned back cavity mask layer.

[0038] The advantages of this invention are: the MEMS device body is led out using device pads, the device pads are covered and protected using an insulating and heat-insulating film, and contact electrical connection with the device pads is achieved through metal lead-out rivets, thus further realizing package lead-out; the back cavity of the MEMS device body is used to achieve further heat insulation, thus obtaining a suspended heat-insulating package suitable for MEMS devices. Under the condition of satisfying the heat insulation package, the lead-out of electrical signals is effectively realized, which is safe and reliable. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of one embodiment of the packaging structure of the present invention.

[0040] Figures 2 to 8 This is a cross-sectional view of one embodiment of the packaging process of the present invention, wherein,

[0041] Figure 2 This is a cross-sectional view of the device pads prepared according to the present invention.

[0042] Figure 3 This is a cross-sectional view of the insulating and heat-insulating film prepared according to the present invention.

[0043] Figure 4 This is a cross-sectional view of the thin film after the lead-out holes are prepared according to the present invention.

[0044] Figure 5 This is a cross-sectional view of the metal lead-out rivet prepared according to the present invention.

[0045] Figure 6 This is a cross-sectional view of the back cavity mask layer prepared according to the present invention.

[0046] Figure 7 This is a cross-sectional view of the back cavity mask layer window prepared for the present invention.

[0047] Figure 8 A cross-sectional view of the prepared dorsal cavity for the present invention.

[0048] Explanation of reference numerals in the attached figures: 1-Device substrate, 2-Metal seed layer, 3-Device pad, 4-Insulating and heat-insulating film, 5-Metal lead-out rivet, 6-Film lead-out hole, 7-Back cavity mask layer, 8-Back cavity mask layer window, 9-Substrate hole, and 10-Seed layer hole. Detailed Implementation

[0049] The present invention will be further described below with reference to specific accompanying drawings and embodiments.

[0050] To effectively achieve thermal insulation packaging of MEMS devices and, while satisfying the thermal insulation packaging requirements, effectively extract electrical signals, a suspended thermal insulation packaging structure suitable for MEMS devices is provided in one embodiment of the present invention, comprising:

[0051] MEMS device body, including a plurality of device pads 3 for leading out the MEMS device body;

[0052] An insulating and heat-insulating film 4 covers the front side of the MEMS device body and is fixedly connected to the front side of the MEMS device body. The device pads 3 are wrapped inside the insulating and heat-insulating film 4.

[0053] The metal lead-out unit includes a plurality of metal lead-out rivets 5, wherein each metal lead-out rivet 5 corresponds one-to-one with a device pad 3, and each metal lead-out rivet 5 is electrically connected to the corresponding device pad 3 through a thin film lead-out hole 6 in an insulating and heat-insulating film 4.

[0054] Specifically, the MEMS device body can be a commonly used existing MEMS device, and the specific form of the MEMS device body can be selected according to actual needs, based on meeting the actual requirements. When performing suspended thermal insulation packaging on the MEMS device, the MEMS device needs to be led out. During the lead-out process, device pads 3 need to be set up for the lead-out. The number and distribution of device pads 3 should be determined based on the ability to lead out the MEMS device.

[0055] An insulating and heat-insulating film 4 is used to cover the MEMS device body. In this case, the insulating and heat-insulating film 4 effectively wraps around the device pads 3. The insulating and heat-insulating film 4 has insulating and heat-insulating capabilities, meaning it will not affect the operation of the MEMS device body or the lead-out state of the MEMS device body via the device pads 3. When the insulating and heat-insulating film 4 is fabricated on the MEMS device body, it is fixed to the MEMS device body, i.e., in a fixed connection state with the MEMS device body.

[0056] As can be seen from the above description, the insulating and heat-insulating film 4 wraps around the device pad 3. Therefore, when the electrical signal of the MEMS device body is brought out through the device pad 3, several thin film lead-out holes 6 need to be prepared in the insulating and heat-insulating film 4. The device pad 3 corresponding to the thin film lead-out hole 6 can be exposed by using a thin film lead-out hole 6.

[0057] The metal lead-out unit includes several metal lead-out rivets 5, the number of which corresponds to the number of device pads 3. Each metal lead-out rivet 5 corresponds directly to a device pad 3 through a thin-film lead-out hole 6, and is electrically connected after contacting the corresponding device pad 3. Figure 1 and Figure 8 As shown.

[0058] In one embodiment of the present invention, the metal lead-out rivet 5 includes a rivet post filled in the thin film lead-out hole 6 and a rivet cap covering the insulating and heat-insulating film 4, wherein,

[0059] The outer diameter of the rivet cap is larger than the outer diameter of the rivet post, and the rivet cap is connected to the corresponding component pad 3 through the rivet post.

[0060] Figure 1 and Figure 8 In this design, the metal lead-out rivet 5 includes a rivet post and a rivet cap. The rivet post fills the lead-out hole 6 in the thin film, and the rivet cap is supported on the insulating and heat-insulating film 4. The rivet cap and the rivet post are generally integrally formed, meaning that the lead-out connection after encapsulation can be achieved through the rivet cap. In specific implementations, the manufacturing process of the rivet post and rivet cap of the metal lead-out rivet 5 includes electroplating; of course, other processes can also be used to prepare the required metal lead-out rivet 5, with the specific process depending on whether it meets the requirements for preparing the metal lead-out rivet 5.

[0061] In one embodiment of the present invention, the insulating and heat-insulating film 4 includes a photoresist layer, a dry film, or a photosensitive tape, wherein,

[0062] When the insulating and heat-insulating film 4 is photosensitive, the process of preparing the film lead-out hole 6 in the insulating and heat-insulating film 4 includes photolithography.

[0063] When the insulating and heat-insulating film 4 does not have photosensitivity, the process of preparing the film lead-out hole 6 in the insulating and heat-insulating film 4 includes laser drilling.

[0064] As can be seen from the above description, the thickness of the insulating and heat-insulating film 4 is greater than the height of the device pad 3. The insulating and heat-insulating film 4 can be made of existing insulating and heat-insulating materials, which can generally be photoresist layers, dry films or photosensitive tapes; of course, it can also be other insulating and heat-insulating material forms, and the specific material should meet the requirements of insulation and heat insulation.

[0065] In practice, when the insulating and heat-insulating film 4 is photosensitive, photolithography is preferred for preparing the film lead-out holes 6. When the insulating and heat-insulating film 4 is not photosensitive, laser drilling is preferred. The specific process conditions and procedures for preparing the film lead-out holes 6 using photolithography or laser drilling can be selected according to actual needs, based on the requirement of preparing the film lead-out holes 6.

[0066] In one embodiment of the present invention, the MEMS device body includes a device substrate 1 and a back cavity adapted to the MEMS device body, wherein,

[0067] Device pad 3 is electrically connected to device substrate 1 via metal seed layer 2;

[0068] The back cavity includes a base hole 9 that penetrates the device substrate 1 and a seed layer hole 10 that penetrates the metal seed layer 2. The base hole 9 and the seed layer hole 10 correspond to each other and are connected.

[0069] To further insulate the heat, a back cavity structure can be provided on the MEMS device body. Figure 1 and Figure 8 In this design, the MEMS device body includes a device substrate 1, which can be a commonly used silicon substrate. Alternatively, other substrate materials can be used, depending on the specific requirements. The MEMS device structure is fabricated on the device substrate 1. A metal seed layer 2 is then fabricated on the device substrate 1 containing the MEMS device structure. The distribution of the metal seed layer 2 on the device substrate 1 is designed to facilitate the extraction of the MEMS device, while ensuring that its placement does not interfere with the normal operation of the MEMS device.

[0070] The metal seed layer 2 can be made of existing metals, such as copper, and the specific fabrication process of the metal seed layer 2 can be selected as needed. After fabricating the metal seed layer 2, the device pads 3 are fabricated on the metal seed layer 2, at which point the device pads 3 are brought out to the MEMS device body.

[0071] The back cavity includes the base hole 9 and the seed layer hole 10. The distribution of the base hole 9 and the seed layer hole 10 is such that it does not affect the MEMS device. Generally, the device pads 4 are distributed on the outer ring of the back cavity.

[0072] The aforementioned suspended thermal insulation encapsulation structure can be prepared through the following process steps. In one embodiment of the present invention, the preparation method includes the following steps:

[0073] A MEMS device body is provided, and a plurality of device pads 3 are prepared for leading out the MEMS device body, wherein the device pads 3 are located on the front side of the MEMS device body.

[0074] An insulating and heat-insulating film 4 is fabricated on the aforementioned MEMS device body, wherein the insulating film 4 covers the front side of the MEMS device body and is fixedly connected to the front side of the MEMS device body, and the device pad 3 is wrapped inside the insulating and heat-insulating film 4.

[0075] A plurality of thin film lead-out holes 6 are prepared within the insulating and heat-insulating film 4, wherein the thin film lead-out holes 6 correspond one-to-one with the device pads 3, and the device pads 3 are exposed by means of the corresponding thin film lead-out holes 6.

[0076] A metal lead-out unit is prepared, wherein the metal lead-out unit includes a plurality of metal lead-out rivets 5, each metal lead-out rivet 5 corresponding one-to-one with a device pad 3, and each metal lead-out rivet 5 is electrically connected to the corresponding device pad 3 through a thin film lead-out hole 6.

[0077] Figure 2In this section, a metal seed layer 2 is prepared on the device substrate 1, and a device pad 3 is prepared on the metal seed layer 2. The specific details of the device substrate 1, the metal seed layer 2, and the device pad 3 can be referred to the above description, and will not be repeated here.

[0078] Figure 3 In the process, an insulating and heat-insulating film 4 is prepared. The insulating and heat-insulating film 4 is supported on the device substrate 1 and the metal seed layer 2, and can cover the device pads 3. The specific details of the insulating and heat-insulating film 4 can be referred to the above description. Specifically, it should be based on the ability to achieve insulation and heat insulation. The thickness of the insulating and heat-insulating film 4 is greater than the height of the device pads 3 on the metal seed layer 2.

[0079] Figure 4 In this process, the insulating and heat-insulating film 4 is subjected to an opening process to prepare a film lead-out hole 6. The preparation process of the film lead-out hole 6 is based on the compatibility with the material of the insulating and heat-insulating film 4. For details, please refer to the above description.

[0080] Figure 5 In this process, metal lead-out rivets 5 are prepared using processes such as electroplating, and metal lead-out units are formed using the prepared metal lead-out rivets 5. As can be seen from the above description, the metal lead-out rivets 5 include rivet posts filled in the thin film lead-out holes 6 and rivet caps covering the insulating and heat-insulating film 4.

[0081] Figures 2 to 5 An embodiment of the front lead-out process is shown in the figure. Figures 6 to 8 The image shows one embodiment of the back cavity, the fabrication process of which includes:

[0082] A cavity mask layer 7 is coated on the back side of the device substrate 1;

[0083] The cavity mask layer 7 is selectively masked and etched to obtain a cavity mask layer window 8 that penetrates the cavity mask layer 7;

[0084] The device substrate 1 and the metal seed layer 2 are etched using the back cavity mask layer 7 and the back cavity mask layer window 8 to obtain the base hole 9 penetrating the device substrate 1 and the seed layer hole 10 penetrating the metal seed layer 2, respectively.

[0085] Remove the aforementioned back cavity mask layer 7.

[0086] Figure 6 In the process, a cavity mask layer 7 is coated on the back side of the device substrate 1. The cavity mask layer 7 can be a photoresist layer. When the cavity mask layer 7 is a photoresist layer, it can be prepared using the commonly used photoresist coating process.

[0087] Figure 7In the process, the cavity mask layer 7 is selectively masked and etched to obtain the cavity mask layer window 8, and the device substrate 1 corresponding to the cavity mask layer window 8 is exposed through the cavity mask layer window 8.

[0088] Figure 8 In the process, the device substrate 1 and the metal seed layer 2 are etched using the back cavity mask layer 7 and the back cavity mask layer window 8 to obtain the base hole 9 penetrating the device substrate 1 and the seed layer hole 10 penetrating the metal seed layer 2, respectively; that is, the back cavity is formed by using the base hole 9 and the seed layer hole 10 that is aligned and connected to the base hole 9. The specific details of the back cavity can be referred to the above description, and will not be repeated here.

[0089] After the seed layer hole 10 is prepared, the back cavity mask layer 7 is removed from the device substrate 1. The removal can be carried out using existing commonly used processes, so as to achieve the removal of the back cavity mask layer 7 without affecting the MEMS device.

[0090] This invention utilizes device pads 3 to bring out the MEMS device body, uses an insulating and heat-insulating film 4 to cover and protect the device pads 3, and uses metal lead-out rivets 5 to achieve contact electrical connection with the device pads 3, thus further realizing the encapsulation lead-out; and uses the back cavity of the MEMS device body to achieve further heat insulation, thus obtaining a suspended heat-insulating package suitable for MEMS devices. Under the condition of satisfying the heat insulation package, the electrical signal is effectively brought out, which is safe and reliable.

Claims

1. A suspended thermally insulated packaging structure suitable for MEMS devices, characterized in that, The suspended heat insulation encapsulation structure includes: MEMS device body, including a number of device pads (3) for leading out the MEMS device body. An insulating and heat-insulating film (4) is covered on the front side of the MEMS device body and is fixedly connected to the front side of the MEMS device body. The device pads (3) are wrapped inside the insulating and heat-insulating film (4). The metal lead-out unit includes a number of metal lead-out rivets (5), wherein the metal lead-out rivets (5) correspond one-to-one with the device pads (3), and one metal lead-out rivet (5) is electrically connected to the corresponding device pad (3) through the thin film lead-out hole (6) in the insulating and heat-insulating film (4). The MEMS device body includes a device substrate (1) and a back cavity adapted to the MEMS device body, wherein, The device pad (3) is electrically connected to the device substrate (1) through the metal seed layer (2); The back cavity includes a base hole (9) that penetrates the device substrate (1) and a seed layer hole (10) that penetrates the metal seed layer (2). The base hole (9) and the seed layer hole (10) correspond to each other and are connected.

2. The suspended thermal insulation packaging structure suitable for MEMS devices according to claim 1, characterized in that: The metal lead-out rivet (5) includes a rivet post filled in the thin film lead-out hole (6) and a rivet cap covering the insulating and heat-insulating film (4), wherein, The outer diameter of the rivet cap is larger than the outer diameter of the rivet post, and the rivet cap is connected to the corresponding device pad (3) through the rivet post.

3. The suspended thermal insulation packaging structure suitable for MEMS devices according to claim 1, characterized in that: The insulating and heat-insulating film (4) includes a photoresist layer, a dry film, or a photosensitive tape, wherein, When the insulating and heat-insulating film (4) is photosensitive, the process of preparing the film lead-out hole (6) in the insulating and heat-insulating film (4) includes photolithography; When the insulating and heat-insulating film (4) does not have photosensitivity, the process of preparing the film lead-out hole (6) in the insulating and heat-insulating film (4) includes laser drilling.

4. The suspended thermal insulation packaging structure suitable for MEMS devices according to claim 2, characterized in that: The manufacturing process of the metal lead-out rivet (5), including the rivet post and rivet cap, includes electroplating.

5. A method for fabricating a suspended thermal insulation packaging structure suitable for MEMS devices, characterized in that, The method for preparing the suspended heat-insulating encapsulation structure according to claim 1 includes the following steps: A MEMS device body is provided, and a plurality of device pads (3) for leading out the MEMS device body are prepared, wherein the device pads (3) are located on the front side of the MEMS device body; An insulating and heat-insulating film (4) is prepared on the above-mentioned MEMS device body, wherein the insulating and heat-insulating film (4) covers the front side of the MEMS device body and is fixedly connected to the front side of the MEMS device body, and the device pad (3) is wrapped inside the insulating and heat-insulating film (4). Prepare a thin film lead-out hole (6) located in the insulating and heat-insulating film (4), wherein the thin film lead-out hole (6) corresponds one-to-one with the device pad (3), and expose the device pad (3) by using the corresponding thin film lead-out hole (6); Prepare a metal lead unit, wherein the metal lead unit includes a plurality of metal lead rivets (5), the metal lead rivets (5) correspond one-to-one with the device pads (3), and a metal lead rivet (5) is electrically connected to the corresponding device pad (3) through a thin film lead hole (6); The MEMS device body includes a device substrate (1) and a back cavity adapted to the MEMS device body, wherein, The device pad (3) is electrically connected to the device substrate (1) through the metal seed layer (2); The back cavity includes a base hole (9) that penetrates the device substrate (1) and a seed layer hole (10) that penetrates the metal seed layer (2). The base hole (9) and the seed layer hole (10) correspond to each other and are connected.

6. The method for fabricating a suitable suspended thermal insulation packaging structure for MEMS devices according to claim 5, characterized in that, The insulating and heat-insulating film (4) includes a photoresist layer, a dry film, or a photosensitive tape, wherein, When the insulating and heat-insulating film (4) is photosensitive, the process of preparing the film lead-out hole (6) in the insulating and heat-insulating film (4) includes photolithography; When the insulating and heat-insulating film (4) does not have photosensitivity, the process of preparing the film lead-out hole (6) in the insulating and heat-insulating film (4) includes laser drilling.

7. The method for fabricating a suitable suspended thermal insulation packaging structure for MEMS devices according to claim 5, characterized in that, The metal lead-out rivet (5) is prepared by a process including electroplating. The metal lead-out rivet (5) includes a rivet post filled in the thin film lead-out hole (6) and a rivet cap covering the insulating and heat-insulating film (4), wherein, The outer diameter of the rivet cap is larger than the outer diameter of the rivet post, and the rivet cap is connected to the corresponding device pad (3) through the rivet post.

8. The method for fabricating a suitable suspended thermal insulation packaging structure for MEMS devices according to claim 5, characterized in that, The fabrication process of the back cavity includes: A cavity mask layer (7) is coated on the back side of the device substrate (1). Selectively mask and etch the cavity mask layer (7) to obtain a cavity mask layer window (8) that penetrates the cavity mask layer (7); The device substrate (1) and the metal seed layer (2) are etched using the back cavity mask layer (7) and the back cavity mask layer window (8) to obtain the base hole (9) penetrating the device substrate (1) and the seed layer hole (10) penetrating the metal seed layer (2), respectively. Remove the aforementioned back cavity mask layer (7).

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