CN212982461U

CN212982461U - Multilayer MEMS structure

Info

Publication number: CN212982461U
Application number: CN202022100291.5U
Authority: CN
Inventors: 吴炫烨; 关一民
Original assignee: Shanghai Industrial Utechnology Research Institute
Current assignee: Shanghai Industrial Utechnology Research Institute
Priority date: 2020-09-22
Filing date: 2020-09-22
Publication date: 2021-04-16
Anticipated expiration: 2030-09-22

Abstract

The utility model provides a multilayer MEMS structure, this MEMS structure include from bottom to top piles up the at least two-layer photosensitive dry film on the substrate in proper order, be equipped with the cavity in the photosensitive dry film. The utility model discloses use at least two-layer photosensitive dry film to realize multilayer MEMS structure, each layer structure is more for leveling, and it is more even to expose, can reduce structural error to improve the yield that multilayer MEMS structure made. The multilayer MEMS structure can be applied to a variety of microstructures including, but not limited to, nanopore sequencing chips.

Description

Multilayer MEMS structure

Technical Field

The utility model belongs to the technical field of micro-electro-mechanical systems (MEMS) device processing, a multilayer MEMS structure is related to.

Background

Micro Electro Mechanical Systems (MEMS for short) have the characteristics of miniaturization, intelligence, multifunction, high integration and suitability for mass production, and the internal structure thereof is generally in the micrometer or even nanometer level, and requires ultra-precise machining, and if the structural error is large, the device performance will be adversely affected.

SUMMERY OF THE UTILITY MODEL

In view of the above-mentioned shortcomings of the prior art, the present invention is directed to a multi-layer MEMS structure for solving the problem of large error of MEMS structure in the prior art.

To achieve the above and other related objects, the present invention provides a multilayer MEMS structure, including:

a substrate;

at least two layers of photosensitive dry films are stacked on the substrate from bottom to top in sequence, and cavities are formed in the photosensitive dry films.

Optionally, the photosensitive dry film has a thickness ranging from 5 micrometers to 1000 micrometers.

Optionally, the cavities in two adjacent layers of the photosensitive dry film are communicated.

Optionally, the opening areas of the cavities in two adjacent layers of the photosensitive dry films are different.

Optionally, an electrode layer is disposed on the surface of the substrate, and the cavity in the photosensitive dry film on the bottom layer is exposed out of the electrode layer.

As described above, the utility model discloses a multilayer MEMS structure uses at least two-layer photosensitive dry film to realize multilayer MEMS structure, and each layer structure is more for leveling, and it is more even to expose, can reduce structural error to improve the yield that multilayer MEMS structure made. The multilayer MEMS structure can be applied to a variety of microstructures including, but not limited to, nanopore sequencing chips.

Drawings

FIG. 1 is a process flow diagram of a method of fabricating a multi-layer MEMS structure.

FIG. 2 is a schematic diagram of a first overlay and patterning step.

FIG. 3 is a schematic diagram of a second coating and patterning step.

Fig. 4 shows a top view of the structure shown in fig. 3.

FIG. 5 is a cross-sectional view of a multi-layer MEMS structure fabricated in another embodiment.

Fig. 6 is a top view of the structure shown in fig. 5.

FIG. 7 is a flow chart illustrating the design and fabrication of a multi-layer MEMS structure.

FIG. 8 is a schematic cross-sectional view of a nanopore sequencing chip using the multi-layered MEMS structure as a support structure.

Description of the element reference numerals

S1-S2

1 substrate

2 first photosensitive dry film

3 first cavity

4 second photosensitive dry film

401 overhang portion

5 second cavity

6 phospholipid layer

7 protein nanopores

8 electrode layer

Detailed Description

The following description of the embodiments of the present invention is provided for illustrative purposes, and other advantages and effects of the present invention will be readily apparent to those skilled in the art from the disclosure herein. The present invention can also be implemented or applied through other different specific embodiments, and various details in the present specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

Please refer to fig. 1 to 8. It should be noted that the drawings provided in the present embodiment are only for illustrating the basic idea of the invention in a schematic manner, and only the components related to the invention are shown in the drawings rather than being drawn according to the number, shape and size of the components in actual implementation, and the form, quantity and proportion of the components in actual implementation may be changed at will, and the layout of the components may be more complicated.

Example one

In the present embodiment, a method for fabricating a multi-layer MEMS structure is provided, please refer to fig. 1, which shows a process flow diagram of the method, including the following steps:

s1: a first laminating and patterning step: covering a first photosensitive dry film on a substrate, and patterning the first photosensitive dry film to obtain a first cavity in the first photosensitive dry film;

s2: a second laminating and patterning step: covering a second photosensitive dry film on the first photosensitive light film, and patterning the second photosensitive dry film to obtain a second cavity in the second photosensitive dry film.

Referring to fig. 2, step S1 is executed: a first laminating and patterning step: covering a first photosensitive dry film 2 on a substrate 1 through a manual or/and automatic film sticking machine, and patterning the first photosensitive dry film 2 to obtain a first cavity 3 in the first photosensitive dry film 2.

Specifically, the substrate 1 serves as a supporting platform, and any suitable material such as a silicon wafer, a lift-off material, a polymer material layer, and the like can be used. The surface of the substrate 1 may be cleaned by chemical or physical methods before the first coating and patterning steps are performed. The thickness of the first photosensitive dry film 2 may be selected according to needs, and may be, for example, 5 to 1000 micrometers. Depending on the type of dry film, the substrate may be heated to 40-90 ℃ to soften the dry film. And a certain pressure, for example 2kPa to 10kPa, may be applied according to the area of the substrate to help dry film coating, and the duration may be 1 to 10 minutes. The patterning may include an ultraviolet light irradiation exposure step, a post-exposure baking step, and a developing step. In this embodiment, after the first photosensitive dry film 2 is patterned, the patterned first photosensitive dry film 2 may be further baked and cured. The shape of the first cavity 3 can be adjusted as desired.

As an example, an electrode layer (not shown in fig. 2, see fig. 8) may be formed on the surface of the substrate 1 in advance, the first cavity 3 exposes the electrode layer, and the electrode layer may include one or more conductive metal layers.

Then, referring to fig. 3, step S2 is executed: a second laminating and patterning step: covering a second photosensitive dry film 4 on the first photosensitive light film 2 through a manual or/and automatic film sticking machine, and imaging the second photosensitive dry film 4 to obtain a second cavity 5 in the second photosensitive dry film 4.

Specifically, the thickness of the second photosensitive dry film 4 may be selected according to needs, and may be, for example, 5 to 1000 micrometers. Depending on the type of dry film, the substrate may be heated to 40-90 ℃ to soften the dry film. And a certain pressure, for example 2kPa to 10kPa, may be applied according to the area of the substrate to help dry film coating, and the duration may be 1 to 10 minutes. The patterning may include an ultraviolet light irradiation exposure step, a post-exposure baking step, and a developing step. In this embodiment, after the second photosensitive dry film 4 is patterned, the patterned dry film may be further baked and cured. The shape of the second cavity 5 can be adjusted as desired.

Referring to fig. 4, which is a top view of the structure shown in fig. 3, in the present embodiment, the second cavity 5 is communicated with the first cavity 3, and an opening area of the second cavity 5 is larger than an opening area of the first cavity 3.

Referring to fig. 5 and 6, wherein fig. 5 is a cross-sectional view of the MEMS structure fabricated in another embodiment, and fig. 6 is a top view of the structure shown in fig. 5, in this embodiment, an opening area of the second cavity 5 is smaller than an opening area of the first cavity 3, a portion of the second photosensitive dry film 4 is suspended above the first cavity 3, and fig. 6 marks a suspended portion 401 of the second photosensitive dry film 4.

Thus, a multilayer MEMS structure comprising two layers of photosensitive dry films is fabricated. In other embodiments, the laminating and patterning steps can be performed at least once, as required, to obtain at least three (e.g., 3-10, or more) patterned photosensitive dry films sequentially stacked on the substrate from bottom to top. Referring to fig. 7, a flow chart of a design and fabrication of a multi-layer MEMS structure is shown, comprising the following process steps:

(1) determining the number of layers of the MEMS structure and the photoetching process conditions of each layer;

(2) cleaning a substrate;

(3) dry film lamination is carried out by using a manual or automatic method;

(4) patterning the dry film of the coating;

(5) baking and curing the patterned dry film;

(6) and (5) repeating the steps (2) to (5) at least once to complete the MEMS structure with the corresponding layer number.

Specifically, each time of film covering can be completed through a manual or/and automatic film sticking machine, the thickness of each layer of photosensitive dry film can be adjusted according to needs, and the thicknesses of different layers can be the same or different. According to the type of the dry film, during or after each lamination process, the substrate can be heated to a preset temperature, and a preset pressure is applied to the surface of the covered photosensitive dry film to assist in lamination.

The multilayer MEMS structure fabricated in this embodiment can be applied to various microstructures, and the following description will be given by taking the application to a nanopore sequencing chip as an example. There are three main types of sequencing products on the market, which are based on the 2 nd, 3 rd and 4 th generation sequencing technologies. The second generation sequencing technology chip is processed by processing circular groove array on glass and modifying the DNA fragment for sequencing in the groove array. The chip of the third generation sequencing technology is to process nanometer micropores on metal by a semiconductor process. The fourth generation sequencing technology chip is a support structure for processing protein nanopores by semiconductor processing using photoresist. Of which fourth generation sequencing technology is also known as nanopore sequencing technology. The basic working principle of the nanopore is that in a cavity filled with electrolyte, an insulating impermeable membrane with a nanoscale pore divides the cavity into two small chambers, and when voltage is applied to the electrolyte chamber, ions or other small molecular substances can pass through the pore to form stable detectable ionic current. Different types of biomolecules can be detected by grasping the size and surface characteristics of the nanopore, the applied voltage and the solution conditions. Because the four bases of adenine (A), guanine (G), cytosine (C) and thymine (T) which form DNA have different molecular structures and sizes, single-stranded DNA (ssDNA) is rapidly cut into deoxyribonucleotide molecules one by one under the action of exonuclease, and when a single base passes through a nano-scale pore under the driving of an electric field, the change amplitude of current caused by the difference of chemical properties of different bases when passing through the nano-scale pore is different, thereby obtaining the sequence information of the detected DNA.

In the fourth generation sequencing technology chips, the support structure mainly functions to form a phospholipid layer to fix protein nanopores, and is generally composed of a multilayer structure. Please refer to fig. 8, which shows a schematic cross-sectional structure of a nanopore sequencing chip using the above-mentioned fabricated multi-layer MEMS structure as a supporting structure (only two layers of photosensitive dry films are illustrated in fig. 8, in practical applications, the number of layers of the photosensitive dry films may be more than two layers), the nanopore sequencing chip includes a sample cavity, a phospholipid layer 6 and a protein nanopore 7, the first cavity 3 surrounded by the first photosensitive dry film 2 and the second cavity 5 surrounded by the second photosensitive dry film 4 of the MEMS structure are used as components of the sample cavity, the phospholipid layer 6 is fixed on the inner wall of the sample cavity, that is, supported by the photosensitive dry films and suspended in the sample cavity to divide the sample cavity into an upper part and a lower part, the protein nanopore 7 is connected to the phospholipid layer 6 and penetrates through the phospholipid layer 6 in the vertical direction, that is, the protein nanopore 7 is embedded in the phospholipid layer 6. In this embodiment the bottom of the sample chamber is provided with an electrode layer 8, which is one electrode of the test circuit. Which base is passed can be determined by measuring the change in current during the passage of DNA through the protein nanopore and decoding the current information.

Compared with the method for manufacturing the structure with the large thickness by adopting the liquid photoresist, the film layer is not flat due to spin coating, and then the contact exposure is not uniform, so that the final structural error is large, the manufacturing of the multilayer MEMS structure is realized by using at least two layers of photosensitive dry films in the embodiment, each layer of structure is more flat, the exposure is more uniform, the structural error can be reduced, and the yield of the multilayer MEMS structure is improved. The fabricated multilayer MEMS structure can be applied to a variety of microstructures including, but not limited to, nanopore sequencing chips.

Example two

The embodiment provides a multilayer MEMS structure, which comprises a substrate and at least two layers of photosensitive dry films stacked on the substrate from bottom to top in sequence, wherein a cavity is arranged in each photosensitive dry film.

As an example, the thickness of the photosensitive dry film ranges from 5 micrometers to 1000 micrometers, the thickness of each photosensitive dry film can be adjusted according to needs, and the thicknesses of different layers may be the same or different.

As an example, the cavities in two adjacent layers of the photosensitive dry films are communicated, and the opening areas of the cavities in two adjacent layers of the photosensitive dry films are different.

As an example, the substrate surface is provided with an electrode layer, and the cavity in the bottom photosensitive dry film exposes the electrode layer.

The multilayer MEMS structure of the present embodiments can be applied to a variety of microstructures, including but not limited to nanopore sequencing chips. Illustratively, the nanopore sequencing chip comprises a sample cavity, a phospholipid layer and a protein nanopore, wherein the cavity in each layer of the photosensitive dry film is used as a component of the sample cavity, the phospholipid layer is fixed on the inner wall of the sample cavity and suspended in the sample cavity, and the protein nanopore is connected with the phospholipid layer and penetrates through the phospholipid layer in the vertical direction.

To sum up, the utility model discloses a multilayer MEMS structure uses at least two-layer photosensitive dry film to realize multilayer MEMS structure, includes at least two-layer photosensitive dry film in this multilayer MEMS structure, and each layer structure is more for leveling, and it is more even to expose, can reduce structural error to improve the yield that multilayer MEMS structure made. The multilayer MEMS structure can be applied to a variety of microstructures including, but not limited to, nanopore sequencing chips. Therefore, the utility model effectively overcomes various defects in the prior art and has high industrial utilization value.

The above embodiments are merely illustrative of the principles and effects of the present invention, and are not to be construed as limiting the invention. Modifications and variations can be made to the above-described embodiments by those skilled in the art without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which may be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.

Claims

1. A multi-layer MEMS structure, comprising:

a substrate;

at least two layers of photosensitive dry films are sequentially stacked on the substrate from bottom to top, a cavity is arranged in each photosensitive dry film, and the cavities in the photosensitive dry films are communicated with each other.

2. The multi-layer MEMS structure of claim 1, wherein: the thickness range of the photosensitive dry film is 5-1000 microns.

3. The multi-layer MEMS structure of claim 1, wherein: the opening areas of the cavities in the two adjacent layers of the photosensitive dry films are different.

4. The multi-layer MEMS structure of claim 1, wherein: the surface of the substrate is provided with an electrode layer, and the cavity in the photosensitive dry film positioned at the bottom layer is exposed out of the electrode layer.