Method for manufacturing a microvia array metal screen and metal screen thereof

Abstract

The application provides a micro via array metal filter manufacturing method and a metal filter thereof. The micro via array metal filter manufacturing method comprises the following steps: manufacturing a photoetching mask; forming a titanium nitride film on one side of a silicon wafer; bonding to form a glass-titanium nitride film-silicon wafer three-layer sandwich structure; spin coating photoresist on the outer side of the silicon wafer, placing the photoetching mask to expose the photoresist, post-baking, developing, then etching the non-resin area on the silicon wafer, and removing the photoresist to obtain a micro column array silicon wafer structure; pulse electroforming, stripping the electroformed metal micro hole structure from the silicon wafer to obtain a metal filter; and removing silicon from the obtained metal filter to obtain a micro via array metal filter with a preset thickness. The application can prepare a micro via array metal filter with a depth-width ratio greater than 50:1, greatly improves the processing efficiency of the metal filter, and most importantly, ensures the uniformity and consistency of the micro vias in the metal filter, with a CV value less than 5%.

Description

Technical Field

[0001] This invention belongs to the field of advanced manufacturing, specifically relating to a method for manufacturing a micro-pore array metal filter and the metal filter thereof. Background Technology

[0002] The precision manufacturing of microvias has extremely important and wide-ranging applications in fields such as bioengineering, electronics, industrial wastewater treatment, and microfluidic components. The use of components with microvias as their core structure is increasing, while the requirements for hole diameter, hole spacing, and precision are becoming smaller and higher. Different fields also have different requirements for the shape and size of the holes. Traditional mechanical machining methods for microvias cannot process high aspect ratio microvias with diameters of micrometers or even submicrometers. While femtosecond laser processing has solved the problem of microvia manufacturing, it is difficult to simultaneously achieve high processing efficiency, consistency, and precision.

[0003] Metal filters, as the most widely used microporous materials, have gained increasing popularity due to their high plasticity, good stability, low cost, and reusability. They are widely used in filtering circulating tumor cells, separating oil and water mixtures, treating wastewater, and detecting solid particle contamination in hydraulic systems. Their uniform permeability can also be used to prepare various fluid distribution elements.

[0004] Therefore, how to effectively apply metal microporous array filters and their manufacturing methods to various fields, improve the processing efficiency of metal filters and the aspect ratio of microporous structures, accurately control the microporous structure, pore size and spacing, and ensure through holes and consistency are the technical problems that urgently need to be solved in this field. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is to provide a method for manufacturing a micro-hole array metal filter and the metal filter thereof, so as to overcome the limitations of the traditional mechanical processing method for micro-holes in the prior art, which cannot process micro-holes with high aspect ratios and diameters of micrometers or even submicrometers. Although the femtosecond laser processing method has solved the problem of micro-hole manufacturing, it is difficult to balance the processing efficiency, consistency and accuracy of micro-holes.

[0006] To address the above problems, the present invention provides a method for manufacturing a microporous array metal filter screen, comprising the following steps:

[0007] The photomask fabrication steps involve fabricating the photomask according to the geometric design requirements of the metal filter.

[0008] The etching stop layer preparation step involves placing a silicon wafer in a chemical vapor deposition chamber to form a titanium nitride thin film on one side of the wafer, wherein the titanium nitride thin film constitutes the etching stop layer.

[0009] In the component formation step, the silicon wafer with the titanium nitride thin film is bonded to glass to form a glass-titanium nitride thin film-silicon wafer three-layer sandwich structure.

[0010] The fabrication steps of the micropillar array structure are as follows: spin-coating photoresist on the outer surface of the silicon wafer in the three-layer sandwich structure, placing the photomask on one side of the photoresist to expose and bake the photoresist, then developing the baked photoresist in a developing solution, then etching the non-photoresist areas on the silicon wafer, and finally removing the photoresist to obtain the micropillar array silicon wafer structure.

[0011] The microporous electroforming step involves using pulse electroforming to electroform the micropillar array silicon wafer structure, and then peeling the electroformed metal microporous structure off the silicon wafer to obtain the metal filter screen.

[0012] The silicon removal process involves removing silicon from the obtained metal filter to obtain a microporous array metal filter of a preset thickness.

[0013] In some implementations...

[0014] The thickness of the etching stop layer is 50-100 nm; and / or, in the micropillar array structure fabrication step, a dry etching method is used to etch the non-adhesive area on the silicon wafer.

[0015] In some implementations...

[0016] The thickness of the formed metal filter is less than the thickness of the silicon wafer; and / or, the metal filter is made of any one of three metals: nickel, iron, and copper.

[0017] In some embodiments, during the etching stop layer preparation step,

[0018] The flow rate of argon was set to 20 sccm, the flow rate of nitrogen was set to 100 sccm, and the power was set to 1500W.

[0019] In some embodiments, during the component formation step, the bonding temperature of the silicon wafer to the glass is 400°C, the voltage is 1000V, and the bonding pressure is 0.5MPa.

[0020] In some embodiments, during the fabrication of the micropillar array structure, the photoresist is SU-8 negative photoresist with an exposure dose of 26 mJ / cm². 2 The post-baking temperature was 60℃ and the post-baking time was 30 min; the development time was 5 min; the etching gas used was SF6, the radio frequency power was 800W, and the gas flow rate was 50 sccm.

[0021] In some embodiments, the micropore electroforming step uses a current of 2A, a frequency of 5Hz, and a positive / negative pulse duty cycle of 5%.

[0022] In some embodiments, the desiliconization process involves soaking the sample in a 30% KOH solution at 80°C for 4 hours.

[0023] The present invention also provides a micro-pore array metal filter screen, which is manufactured using the above-described method for manufacturing micro-pore array metal filter screens.

[0024] In some embodiments, the microporous array metal filter includes a metal outer ring and a central microporous array mesh structure located inside the metal outer ring.

[0025] This invention provides a method for manufacturing a micro-perforated array metal filter and the metal filter thereof. Unlike existing technologies such as femtosecond lasers, this invention combines multiple technologies such as titanium nitride deposition, titanium nitride coating and glass bonding, photolithography, silicon etching and electroforming to produce a micro-perforated array metal filter with an aspect ratio greater than 50:1. The manufacturing method of this invention can precisely control the micropore structure, pore size and pore gap of the metal micro-perforated array filter, which greatly improves the processing efficiency of the metal filter. Most importantly, it ensures the uniformity and consistency of the micropores in the metal filter, with a CV value of less than 5%. Attached Figure Description

[0026] Figure 1 This is a schematic diagram illustrating the steps of a method for manufacturing a microporous array metal filter according to an embodiment of the present invention.

[0027] Figure 2 This is a process flow diagram for manufacturing a microporous array metal filter screen according to an embodiment of the present invention;

[0028] Figure 3 This is a schematic diagram of the structure of a microporous array metal filter screen according to an embodiment of the present invention;

[0029] Figure 4 A planar image of the square array circular microporous array metal filter prepared in Example 1 of the present invention, taken by a scanning electron microscope;

[0030] Figure 5 A planar image taken by a scanning electron microscope of the hexagonal array circular microporous array metal filter prepared in Example 2 of the present invention;

[0031] Figure 6 The image shows a planar view of the square array of microporous metal filters prepared in Example 3 of this invention, taken with a scanning electron microscope. Detailed Implementation

[0032] See also Figures 1 to 6 As shown, according to an embodiment of the present invention, see details. Figure 1 As shown, a method for manufacturing a microporous array metal filter screen is provided, comprising the following steps:

[0033] The photomask fabrication steps involve fabricating a photomask based on the geometric design requirements of the metal filter. Specifically, the aforementioned geometric design includes fabricating a photomask based on requirements such as the outer metal ring, the central micro-hole array mesh structure, the shape, diameter, and spacing of the micro-holes. The shape of the micro-holes can be designed as one or more of the geometric shapes such as circles, rectangles, and triangles, and the micro-hole array can be designed as a square or hexagonal arrangement as needed.

[0034] The etching stop layer preparation step involves placing a silicon wafer into a chemical vapor deposition chamber to form a titanium nitride thin film on one side of the wafer. The titanium nitride thin film constitutes the etching stop layer.

[0035] In the component formation step, a silicon wafer with a titanium nitride thin film is bonded to glass to form a glass-titanium nitride thin film-silicon wafer three-layer sandwich structure.

[0036] The fabrication steps of the micropillar array structure are as follows: spin-coating photoresist on the outer surface of the silicon wafer in the three-layer sandwich structure, placing a photomask on one side of the photoresist to expose and bake the photoresist, then developing the baked photoresist in a developer, then etching the non-photoresist area on the silicon wafer, and finally removing the photoresist to obtain the micropillar array silicon wafer structure.

[0037] The microporous electroforming step involves using pulse electroforming to electroform the micropillar array silicon wafer structure, and then peeling the electroformed metal microporous structure off the silicon wafer to obtain a metal filter screen.

[0038] The silicon removal process involves removing silicon from the obtained metal filter screen to obtain a microporous array metal filter screen of a preset thickness.

[0039] In this technical solution, the etching stop layer formed by the titanium nitride thin film is located below the silicon wafer and has a significantly lower etching rate compared to the silicon wafer. This ensures that the silicon wafer stops uniformly and consistently within the etching stop layer during the etching process. At the same time, titanium nitride is conductive, allowing metal to be deposited into the microstructure during subsequent electroforming. In the process of forming a metal filter screen by electroforming, this invention uses a pulse electroforming process to solve the problems of incomplete microstructure growth caused by high aspect ratio micropit structures, poor flowability of electroforming solution in blind holes, and insufficient metal ion exchange in electroforming solution.

[0040] This invention provides a method for manufacturing a micro-perforated array metal filter, which differs from existing femtosecond laser and other technologies. This invention combines multiple technologies such as titanium nitride deposition, titanium nitride coating and glass bonding, photolithography, silicon etching and electroforming to prepare a micro-perforated array metal filter with an aspect ratio greater than 50:1. The manufacturing method of this invention can precisely control the micropore structure, pore size and pore gap of the metal micro-perforated array filter, which greatly improves the processing efficiency of the metal filter. Most importantly, it ensures the uniformity and consistency of the micropores in the metal filter, with a CV value of less than 5%.

[0041] It is understood that the manufacturing method of the present invention allows for flexible design, adjustment and control of the micropore diameter, pore spacing and the thickness of the metal filter screen.

[0042] In some implementations, the etch stop layer is relatively thick, around 50-100 nm, which is sufficient to stop the etching process. During the fabrication of the micropillar array structure, dry etching, wet etching, or a combination of both are used to etch the non-adhesive areas on the silicon wafer.

[0043] The thickness of the formed metal filter is less than the thickness of the silicon wafer. It should be noted that when the thickness is greater than or equal to the thickness of the silicon wafer, the back of the electroformed metal filter will be completely connected and will not form through holes. That is, through holes can only be formed when the thickness is less than the thickness of the silicon wafer, thereby achieving the technical objective of this invention.

[0044] The metal filter screen is made of any one of three metals: nickel, iron, or copper.

[0045] In some embodiments, during the etching stop layer fabrication step, the argon flow rate is set to 20 sccm, the nitrogen flow rate is set to 100 sccm, and the power is 1500W; during the component formation step, the bonding temperature between the silicon wafer and the glass is 400°C, the voltage is 1000V, and the bonding pressure is 0.5 MPa; during the micropillar array structure fabrication step, the photoresist is SU-8 negative photoresist, and the exposure dose is 26 mJ / cm². 2 The post-baking temperature was 60℃ and the post-baking time was 30 min; the development time was 5 min; SF6 etching gas was used for etching, the RF power was 800W and the gas flow rate was 50 sccm; in the micro-hole electroforming step, the current was 2A, the frequency was 5Hz and the positive / negative pulse duty cycle was 5%; and the silicon removal process was carried out by soaking in a 30% concentration of 80℃ KOH solution for 4 h.

[0046] According to an embodiment of the present invention, a microporous array metal filter screen is also provided, which is manufactured using the above-described method for manufacturing microporous array metal filter screens. The microporous array metal filter screen includes a metal outer ring and a central microporous array mesh structure located inside the metal outer ring. The shape of the metal outer ring can be designed as a circle or a rectangle, etc., as needed. The overall shape of the central microporous array mesh structure can also be designed as a circle or a rectangle, etc., as needed.

[0047] The manufacturing method of the present invention is further described below with reference to several specific embodiments:

[0048] Example 1:

[0049] A microporous array metal filter, such as Figure 3 As shown, it consists of a metal outer ring and a central microporous array mesh structure. The overall shape of the metal outer ring and the central microporous array mesh structure is circular. The mesh structure is located at the center of the filter screen and forms a concentric circle with the metal outer ring. The diameter of the metal outer ring is 8.8 mm, and the diameter of the mesh structure is 6 mm. There are approximately 300,000 micropores.

[0050] A method for preparing a microporous array metal filter, such as... Figure 1 , 2 As shown, it includes the following steps:

[0051] (1) Prepare a tetragonal array photomask with a aperture of 5μm, a center-to-center distance of 10μm, and circular micropores;

[0052] (2) Preparation of etching stop layer: The silicon wafer is placed in the chemical vapor deposition chamber, the flow rate of argon is set to 20 sccm, the flow rate of nitrogen is set to 100 sccm, and the power is 1500W, to form a titanium nitride thin film with a thickness of 50nm on the silicon wafer.

[0053] (3) Bonding the silicon wafer with titanium nitride film to glass at a bonding temperature of 400℃, a voltage of 1000V, and a bonding pressure of 0.5MPa to form a glass-titanium nitride-silicon wafer three-layer sandwich structure.

[0054] (4) Fabrication of micropillar array structure: SU-8 photoresist was spin-coated on a three-layer silicon wafer, and a mask was placed to expose and bake the photoresist. The exposure dose was 26 mJ / cm2, the baking temperature was 60℃, and the time was 30 min. The baked SU-8 photoresist was then developed in a developer for 5 min, rinsed and soaked in isopropanol for 2 min, and dried with nitrogen.

[0055] The non-adhesive areas on the silicon wafer were then etched using SF6 etching gas at a power of 800W and a flow rate of 50sccm, resulting in a micropillar array silicon wafer structure.

[0056] (5) Microporous electroforming: Micropillar structure silicon wafers are electroformed by pulse electroforming with a current of 2A, a frequency of 5Hz, and a positive / negative pulse duty cycle of 5%. The electroformed metal microporous structure is then peeled off from the silicon wafer to obtain a metal filter.

[0057] (6) Desiliconization treatment: The obtained metal filter screen is soaked in a 30% KOH solution at 80℃ for 4 hours to remove silicon, and finally a microporous array metal filter screen with a certain thickness is obtained.

[0058] The obtained microporous tetragonal array nickel filter screen was photographed using a laser confocal microscope (e.g., ...). Figure 4 (As shown) The CV value of the micro-pore diameter was analyzed using ImageJ software, and the pore diameter and pore spacing were measured using a microscope. The obtained pore diameter was 5.02 μm, the standard deviation was 0.12, the center distance was 10.1 μm, and the CV value of the pore diameter of the metal filter screen was 2.4% according to ImageJ analysis.

[0059] Example 2:

[0060] A microporous array metal filter, such as Figure 3 As shown, it consists of a metal outer ring and a central microporous array mesh structure. The overall shape of the metal outer ring and the central microporous array mesh structure is circular. The mesh structure is located at the center of the filter screen and forms a concentric circle with the metal outer ring. The diameter of the metal outer ring is 8.8 mm, and the diameter of the mesh structure is 6 mm, with approximately 400,000 micropores.

[0061] (1) Prepare a hexagonal array photomask with a aperture of 5μm, a center-to-center distance of 10μm, and circular micropores;

[0062] (2) Preparation of etching stop layer: The silicon wafer is placed in the chemical vapor deposition chamber, the flow rate of argon is set to 20 sccm, the flow rate of nitrogen is set to 100 sccm, and the power is 1500W, to form a titanium nitride thin film with a thickness of 50nm on the silicon wafer.

[0063] (3) Bonding the silicon wafer with titanium nitride film to glass at a bonding temperature of 400℃, a voltage of 1000V, and a bonding pressure of 0.5MPa to form a glass-titanium nitride-silicon wafer three-layer sandwich structure.

[0064] (4) Fabrication of micropillar array structure: SU-8 photoresist was spin-coated on a three-layer silicon wafer, and a mask was placed to expose and bake the photoresist. The exposure dose was 26 mJ / cm2, the baking temperature was 60℃, and the time was 30 min. The baked SU-8 photoresist was then developed in a developer for 5 min, rinsed and soaked in isopropanol for 2 min, and dried with nitrogen.

[0065] The non-adhesive areas on the silicon wafer were then etched using SF6 etching gas at a power of 800W and a flow rate of 50sccm, resulting in a micropillar array silicon wafer structure.

[0066] (5) Microporous electroforming: Micropillar structure silicon wafers are electroformed by pulse electroforming with a current of 2A, a frequency of 5Hz, and a positive / negative pulse duty cycle of 5%. The electroformed metal microporous structure is then peeled off from the silicon wafer to obtain a metal filter.

[0067] (6) Desiliconization treatment: The obtained metal filter screen is soaked in a 30% KOH solution at 80℃ for 4 hours to remove silicon, and finally a microporous array metal filter screen with a certain thickness is obtained.

[0068] The obtained microporous hexagonal array nickel filter screen was photographed using a laser confocal microscope (e.g., ...). Figure 5 (As shown) The CV value of the micro-pore diameter was analyzed using ImageJ software, and the pore diameter and pore spacing were measured using a microscope. The obtained pore diameter was 4.98 μm, the standard deviation was 0.124, the center distance was 9.9 μm, and the CV value of the pore diameter of the metal filter screen analyzed by ImageJ was 2.5%.

[0069] Example 3

[0070] A microporous array metal filter, such as Figure 3 As shown, it consists of a metal outer ring and a central microporous array mesh structure. The metal outer ring is circular, and the central microporous array mesh structure is square. The mesh structure is located in the center of the filter and forms a concentric structure with the metal outer ring. The diameter of the metal outer ring is 4 mm, and the diameter of the mesh structure is 1 mm, with approximately 7,000 micropores.

[0071] (1) Prepare a photomask with a side length of 12μm, a spacing of 10μm, and square micropores in a tetragonal array;

[0072] (2) Preparation of etching stop layer: The silicon wafer is placed in the chemical vapor deposition chamber, the flow rate of argon is set to 20 sccm, the flow rate of nitrogen is set to 100 sccm, and the power is 1500W, to form a titanium nitride thin film with a thickness of 50nm on the silicon wafer.

[0073] (3) Bonding the silicon wafer with titanium nitride film to glass at a bonding temperature of 400℃, a voltage of 1000V, and a bonding pressure of 0.5MPa to form a glass-titanium nitride-silicon wafer three-layer sandwich structure.

[0074] (4) Fabrication of micropillar array structure: SU-8 photoresist was spin-coated on a three-layer silicon wafer, and a mask was placed to expose and bake the photoresist. The exposure dose was 26 mJ / cm2, the baking temperature was 60℃, and the time was 30 min. The baked SU-8 photoresist was then developed in a developer for 5 min, rinsed and soaked in isopropanol for 2 min, and dried with nitrogen.

[0075] The non-adhesive areas on the silicon wafer were then etched using SF6 etching gas at a power of 800W and a flow rate of 50sccm, resulting in a micropillar array silicon wafer structure.

[0076] (5) Microporous electroforming: Micropillar structure silicon wafers are electroformed by pulse electroforming with a current of 2A, a frequency of 5Hz, and a positive / negative pulse duty cycle of 5%. The electroformed metal microporous structure is then peeled off from the silicon wafer to obtain a metal filter.

[0077] (6) Desiliconization treatment: The obtained metal filter screen is soaked in a 30% KOH solution at 80℃ for 4 hours to remove silicon, and finally a microporous array metal filter screen with a certain thickness is obtained.

[0078] The obtained square-hole tetrahedral array nickel filter screen was photographed using a laser confocal microscope (e.g., ...). Figure 6 (As shown) The side length and CV value of the micro square holes were analyzed using ImageJ software, and the hole spacing was measured using a microscope. The obtained square hole side length is 12.1 μm, the standard deviation is 0.11, the hole spacing is 10.2 μm, and the CV value of the square hole size of the metal filter screen is 0.9% according to ImageJ analysis.

[0079] It will be readily understood by those skilled in the art that the aforementioned advantageous methods can be freely combined and superimposed without conflict.

[0080] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention. The above are merely preferred embodiments of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the protection scope of the present invention.

Claims

1. A method for manufacturing a microporous array metal filter screen, characterized in that, Includes the following steps: The photomask fabrication steps involve fabricating the photomask according to the geometric design requirements of the metal filter. The etching stop layer preparation step involves placing a silicon wafer in a chemical vapor deposition chamber to form a titanium nitride thin film on one side of the wafer, wherein the titanium nitride thin film constitutes the etching stop layer. In the component formation step, the silicon wafer with the titanium nitride thin film is bonded to glass to form a glass-titanium nitride thin film-silicon wafer three-layer sandwich structure. The fabrication steps of the micropillar array structure are as follows: spin-coating photoresist on the outer surface of the silicon wafer in the three-layer sandwich structure, placing the photomask on one side of the photoresist to expose and bake the photoresist, then developing the baked photoresist in a developing solution, then etching the non-photoresist areas on the silicon wafer, and finally removing the photoresist to obtain the micropillar array silicon wafer structure. The microporous electroforming step involves using pulse electroforming to electroform the micropillar array silicon wafer structure, and then peeling the electroformed metal microporous structure off the silicon wafer to obtain the metal filter screen. The silicon removal process involves removing silicon from the obtained metal filter to obtain a microporous array metal filter of a preset thickness.

2. The manufacturing method according to claim 1, characterized in that, The thickness of the etching stop layer is 50-100 nm; and / or, in the micropillar array structure fabrication step, a dry etching method is used to etch the non-adhesive areas on the silicon wafer.

3. The manufacturing method according to claim 1, characterized in that, The thickness of the formed metal filter is less than the thickness of the silicon wafer; and / or, the metal filter is made of any one of three metals: nickel, iron, and copper.

4. The manufacturing method according to claim 1, characterized in that, In the etching stop layer preparation step The flow rate of argon was set to 20 sccm, the flow rate of nitrogen was set to 100 sccm, and the power was set to 1500W.

5. The manufacturing method according to claim 1, characterized in that, In the component formation step, the bonding temperature of the silicon wafer to the glass is 400°C, the voltage is 1000V, and the bonding pressure is 0.5MPa.

6. The manufacturing method according to claim 1, characterized in that, In the fabrication step of the micropillar array structure, the photoresist is SU-8 negative photoresist, and the exposure dose is 26 mJ / cm. 2 The post-baking temperature was 60℃ and the post-baking time was 30 min; the development time was 5 min; the etching gas used was SF6, the radio frequency power was 800W, and the gas flow rate was 50 sccm.

7. The manufacturing method according to claim 1, characterized in that, In the microporous electroforming step, the current is 2A, the frequency is 5Hz, and the positive / negative pulse duty cycle is 5%.

8. The manufacturing method according to claim 1, characterized in that, In the desiliconization process, the sample is soaked in a 30% KOH solution at 80°C for 4 hours.

9. A microporous array metal filter screen, characterized in that, It is manufactured using the manufacturing method of any one of claims 1 to 8 for a microporous array metal filter.

10. The microporous array metal filter screen according to claim 9, characterized in that, It includes a metal outer ring and a central micro-hole array mesh structure located inside the metal outer ring.

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