Micro coaxial transmission line substrate stripping method and micro coaxial transmission line

Abstract

The invention provides a micro-coaxial transmission line substrate stripping method and a micro-coaxial transmission line, and belongs to the technical field of micro-coaxial production, and the stripping method comprises the steps: obtaining a wafer substrate; wherein the wafer substrate is made of a transparent material; bonding a metal sheet on the wafer substrate; preparing a micro coaxial transmission line on the metal sheet; wherein the metal activity of the metal sheet is higher than that of copper; and de-bonding the wafer substrate and the metal sheet by adopting a laser de-bonding process, so that the wafer substrate is separated from the metal sheet. The stripping method is simple, convenient and efficient to operate, the wafer substrate and the device can be conveniently and losslessly separated after the micro coaxial device is processed, and the integrity and the performance of the device are kept; and the separated substrate is not damaged and can be repeatedly used, so that the material and the production cost can be saved.

Description

Technical Field

[0001] The invention relates to the technical field of micro-coaxial production, and in particular to a stripping method for a micro-coaxial transmission line substrate and a micro-coaxial transmission line. Background Art

[0002] As a basic circuit unit of RF devices prepared by micro-electromechanical system (MEMS) process technology, micro-coaxial transmission line has many advantages such as small size, light weight, low loss, high isolation and good heat dissipation performance. In recent years, it has become a hot spot in millimeter wave RF technology research. In the production process of micro-coaxial transmission line, the device is usually manufactured on a silicon wafer substrate through a multi-layer stacking process, such as thick photoresist lithography, electroplating, planarization and other steps, and finally the device is formed by sacrificial layer release technology. In micro-coaxial transmission line devices, the outer conductor itself is similar to an independent packaging structure. In many cases, the bottom surface of the outer conductor needs to be used directly in the form of grounding, and after the processing is completed, it has lost its main function as a substrate carrier in the device processing process. Therefore, micro-coaxial devices usually remove the wafer used as a substrate during the processing process.

[0003] Prior art CN115411476A discloses a miniaturized all-metal micro-coaxial microwave filter chip, which includes: a filter outer conductor, a micro-coaxial inner conductor and a radio frequency port. In the scheme disclosed in the application, a micro-coaxial process is used for layered preparation, and micro-machining processes such as spin coating photoresist, photoresist leveling, drying, exposure, development, electroforming, grinding, polishing, etc. are repeatedly applied on a silicon wafer substrate. After completing the preparation of each layer, the silicon wafer substrate is removed by a grinding process, and finally the photoresist is removed to complete the processing of the filter. However, the method of removing the substrate by a grinding process causes irreversible damage to the substrate, and it is also impossible to avoid damaging the bottom surface of the device layer adjacent to the substrate.

[0004] Therefore, it is necessary to improve the existing method of removing the substrate of the micro coaxial transmission line to overcome the defects of the prior art. Summary of the invention

[0005] In order to overcome the problems existing in the related art, one of the purposes of the present invention is to provide a method for stripping a micro-coaxial transmission line substrate. The stripping method is simple and efficient to operate, and can conveniently and losslessly separate the wafer substrate from the device after processing the micro-coaxial device, thereby maintaining the integrity and performance of the device; and the substrate will not be damaged after separation and can be reused repeatedly, which can save materials and production costs.

[0006] A method for stripping a micro-coaxial transmission line substrate, comprising:

[0007] Obtain a wafer substrate; wherein the wafer substrate is made of a transparent material;

[0008] bonding a metal sheet onto a wafer substrate;

[0009] A micro-coaxial transmission line is prepared on a metal sheet, wherein the metal activity of the metal sheet is stronger than the metal activity of copper;

[0010] The wafer substrate and the metal sheet are debonded by a laser debonding process, so that the wafer substrate and the metal sheet are separated.

[0011] In a preferred technical solution of the present invention, after the wafer substrate is separated from the metal sheet, the method further comprises:

[0012] The metal sheet is removed by using a corrosive solution to complete the peeling of the micro-coaxial transmission line and the metal sheet.

[0013] In a preferred technical solution of the present invention, bonding a metal sheet on a wafer substrate comprises:

[0014] Apply bonding glue on the wafer substrate and perform preliminary baking;

[0015] Apply bonding glue on the metal sheet and bake it;

[0016] The bonding adhesive on the wafer substrate is relatively fitted with the bonding adhesive on the metal sheet, and the substrate and the metal sheet are bonded by vacuum hot pressing.

[0017] In a preferred technical solution of the present invention, the bonding glue is a laser separation type liquid bonding glue.

[0018] In a preferred technical solution of the present invention, after the wafer substrate and the metal sheet are debonded by the laser debonding process, the method further comprises:

[0019] The residual bonding glue on the surface of the wafer substrate and the iron foil is cleaned and erased using a cleaning agent.

[0020] In a preferred technical solution of the present invention, the wafer substrate is a light-transmitting wafer, and the surface roughness Ra of the wafer substrate is less than 0.5 nm, the thickness is 0.5-1 mm, and the TTV is less than 10 μm.

[0021] In a preferred technical solution of the present invention, the size of the cross section of the metal sheet is the same as the size of the cross section of the wafer substrate; the thickness of the metal sheet is 0.2 mm-0.5 mm.

[0022] In a preferred technical solution of the present invention, the preparation of the micro-coaxial transmission line on the metal sheet includes:

[0023] The micro-coaxial transmission line is manufactured by using the processes of seed layer growth, thick resist photolithography, copper electroplating, and planarization;

[0024] And the thickness of the seed layer is greater than 0.5 μm.

[0025] A second object of the present invention is to provide a micro-coaxial transmission line. During the manufacturing process of the transmission line, the substrate is peeled off by adopting the above-mentioned micro-coaxial transmission line substrate peeling method to obtain the main body of the micro-coaxial transmission line.

[0026] In a preferred technical solution of the present invention, the main body of the micro-coaxial transmission line includes an outer conductor, an inner conductor and an inner conductor support layer, the outer conductor is arranged on the periphery of the inner conductor, and the inner conductor support layer penetrates the inner conductor and connects to the outer conductor.

[0027] The beneficial effects of the present invention are:

[0028] The present invention provides a stripping method for a micro-coaxial transmission line substrate, the stripping method comprising: obtaining a wafer substrate; wherein the wafer substrate is made of a transparent material; bonding a metal sheet on the wafer substrate; preparing a micro-coaxial transmission line on the metal sheet; wherein the metal activity of the metal sheet is stronger than the metal activity of copper; and using a laser debonding process to debond the wafer substrate and the metal sheet, so that the wafer substrate and the metal sheet are separated. The stripping method is simple and efficient to operate. During the production process, the metal sheet is bonded to the wafer substrate, and after the micro-coaxial transmission line on the metal sheet is prepared, the laser debonding process can be used to separate the wafer substrate from the device without damaging the micro-coaxial device, which can ensure the integrity and performance of the device. Compared with traditional physical or chemical stripping methods, the laser debonding process is simpler to operate and more efficient, and because the wafer substrate will not be damaged during the separation process, it can be reused repeatedly after proper cleaning and treatment, reducing the demand for new materials, thereby saving material costs and production costs.

[0029] The present application also provides a micro-coaxial transmission line manufactured by adopting the above-mentioned micro-coaxial transmission line substrate stripping method. Since the micro-coaxial transmission line adopts a non-destructive stripping method, the structure of the micro-coaxial transmission line will not be damaged during the stripping process, thereby ensuring the integrity and reliability of the device. Moreover, the substrate in the production process can be reused, so that the micro-coaxial transmission line can have better cost-effectiveness in the market by saving materials and production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Reference numerals:

[0031] 1. Substrate; 2. Bonding glue; 3. Metal sheet; 4. Seed layer; 100. Outer conductor; 200. Inner conductor; 300. Inner conductor support layer.

[0033] Figure 1 is a flow chart of a method for stripping a micro-coaxial transmission line substrate provided by an embodiment of the present invention;

[0034] Figure 2 is a flow chart of bonding a metal sheet on a wafer substrate provided by an embodiment of the present invention;

[0035] Figure 3 is a schematic diagram of a wafer substrate provided by an embodiment of the present invention;

[0036] Figure 4 is a schematic diagram of coating a bonding adhesive provided by an embodiment of the present invention on a wafer substrate;

[0037] Figure 5 is a schematic diagram of a bonding adhesive provided by an embodiment of the present invention being coated on a metal sheet;

[0038] Figure 6 is a schematic diagram of the structure after the metal sheet and the wafer substrate are bonded together according to an embodiment of the present invention;

[0039] Figure 7 The seed layer provided by the embodiment of the present invention is grown on Figure 5 Schematic diagram of the structure on the metal sheet;

[0040] Figure 8 is a schematic structural diagram of a micro-coaxial transmission line on a seed layer provided by an embodiment of the present invention;

[0041] Fig. 9 is a schematic structural diagram of a micro-coaxial transmission line after the substrate is peeled off provided by an embodiment of the present invention;

[0042] Fig.10 It is a schematic structural diagram of a micro-coaxial transmission line without a metal sheet provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0043] The preferred embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the preferred embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to make the present invention more thorough and complete, and to fully convey the scope of the present invention to those skilled in the art.

[0044] In the prior art, in the preparation process of the micro-coaxial transmission line, a grinding method is usually used to remove the substrate of the micro-coaxial device. However, the method of removing the substrate by grinding process causes irreversible damage to the substrate, and it is also impossible to avoid damaging the bottom surface of the device layer adjacent to the substrate.

[0045] Based on this, the present application provides a method for stripping a micro-coaxial transmission line substrate.

[0046] Example 1

[0047] like Figure 1-Figure 2As shown, this embodiment provides a method for stripping a micro-coaxial transmission line substrate, comprising:

[0048] S100, obtaining a wafer substrate 1; wherein the wafer substrate is made of a transparent material; specifically, in the method claimed for protection in the present application, the wafer substrate 1 is a light-transmitting wafer, and the surface of the wafer substrate is smooth, and the wafer substrate should have good rigidity and flatness, for example, a roughness Ra <0.5nm, a thickness of 0.5-1mm, and a total thickness variation (TTV) of less than 10μm.

[0049] S200, bonding a metal sheet 3 on a wafer substrate; the metal sheet of the present application may be an iron foil.

[0050] In a specific embodiment, bonding a metal sheet on a wafer substrate includes:

[0051] S201, coating bonding glue 2 on the wafer substrate and performing preliminary baking;

[0052] Specifically, during the bonding adhesive coating process on the wafer substrate, a wafer spinner can be used for spin coating, with the rotation speed set to 1500rpm and the spin coating time set to 60 seconds to ensure the uniformity of the adhesive layer. The coated wafer substrate is placed in an oven for preliminary baking at 110°C for 5 minutes and then at 220°C for 10 minutes to promote the initial curing of the adhesive layer. By precisely controlling the thickness of the coating adhesive and the baking conditions, as well as using vacuum hot pressing technology, the bonding strength and stability between the wafer substrate and the metal sheet are ensured, providing a solid foundation for the subsequent preparation of micro-coaxial transmission lines.

[0053] S202, coating bonding glue 2 on the metal sheet 3 and baking;

[0054] S203, the bonding adhesive on the wafer substrate is relatively attached to the bonding adhesive on the metal sheet, and the substrate and the metal sheet are bonded by vacuum hot pressing. During the bonding adhesive coating process of the metal sheet, a blade scraping method can be used to ensure the uniformity of the adhesive layer.

[0055] More specifically, the bonding adhesive is a laser-detachable liquid bonding adhesive. In the present application, a liquid bonding adhesive capable of laser debonding is selected, and the laser-detachable temporary bonding adhesive used can be effectively removed in the subsequent stripping process, so that the wafer substrate can be reused, thereby improving the utilization rate of materials and reducing resource waste.

[0056] S300, preparing a micro-coaxial transmission line on a metal sheet; wherein the metal activity of the metal sheet is stronger than the metal activity of copper;

[0057] S400, debonding the wafer substrate and the metal sheet using a laser debonding process, so that the wafer substrate and the metal sheet are separated.

[0058] Furthermore, after the wafer substrate is separated from the metal sheet, the method further includes:

[0059] S500, using a corrosive solution to remove the metal sheet, completing the separation of the micro-coaxial transmission line and the metal sheet. Usually, the micro-coaxial transmission line is generally realized by electroplating copper. According to the order of metal activity, a solution that can corrode the iron foil but not the metal copper is selected, and the separated metal sheet and the micro-coaxial device on its surface are placed in the corrosive solution to corrode and remove all the metal sheets.

[0060] In the process of preparation and processing of existing micro-coaxial devices, since it involves processes such as glue uniformity, electroplating, and flattening, it is necessary to keep the substrate rigid and flat. Flexible substrates cannot be used. If devices such as micro-coaxial transmission lines are directly prepared on rigid substrates, the bottom surface of the device will be firmly connected to the substrate through the seed layer grown by sputtering, and it is not easy to achieve flexible separation. Thinner sacrificial metal substrates are not rigid enough, and it is difficult to maintain the flatness of the substrate during the preparation of micro-coaxial line manufacturing. However, if a sacrificial metal substrate with thick glue is used, the processing process is difficult to control and the time is too long when the substrate is finally removed. Therefore, the temporary bonding method used in this application can effectively solve the above contradiction by bonding a thin sacrificial metal substrate with a flat and rigid wafer substrate. The laser debonding process in this application is simple and efficient to operate, and can conveniently separate the rigid substrate after processing the micro-coaxial device.

[0061] In a more preferred embodiment, after the wafer substrate and the metal sheet are debonded by the laser debonding process, the method further comprises:

[0062] The residual bonding glue on the surface of the wafer substrate and the iron foil is cleaned and erased using a cleaning agent.

[0063] Specifically, the residual bonding adhesive on the surface of the wafer substrate and the iron foil can be cleaned with a primary cleaning agent corresponding to the selected bonding adhesive to ensure the cleanliness of the device surface. After the primary cleaning, use isopropyl alcohol for the final cleaning again to remove any possible residual cleaning

[0064] Furthermore, the size of the cross section of the metal sheet is the same as the size of the cross section of the wafer substrate; and the thickness of the metal sheet is 0.2 mm-0.5 mm.

[0065] The cross-sectional dimensions of the metal sheet and the wafer substrate are perfectly matched, which can ensure more uniform contact between the two during the bonding process and reduce bonding defects caused by size mismatch. In addition, the precise size matching between the metal sheet and the substrate wafer helps to improve the uniformity of the bonding glue distribution, thereby improving the bonding quality and ensuring the stability of the micro-coaxial transmission line during the preparation process.

[0066] Furthermore, the preparation of the micro-coaxial transmission line on the metal sheet comprises:

[0067] The micro-coaxial transmission line is manufactured by using the processes of seed layer growth, thick resist photolithography, copper electroplating, and planarization;

[0068] The thickness of the seed layer 4 is greater than 0.5 μm. The present application limits the thickness of the seed layer 4 to be greater than 0.5 μm, which can provide good electroplating adhesion and conductivity for the manufacture of micro-coaxial transmission lines, thereby enhancing the conductivity of the micro-coaxial transmission lines.

[0069] More specifically, the process of preparing a micro-coaxial transmission line on a metal sheet is as follows:

[0070] Seed layer preparation: A 20 nm thick titanium adhesion layer is sputtered on the surface of a silicon wafer with an oxide layer by magnetron sputtering, and then a seed layer with a thickness greater than 0.5 μm is sputtered on the adhesion layer.

[0071] Thick photolithography: Use a spin coater to spin-coat a layer of photoresist with a thickness greater than 100 microns on the surface of the seed layer. Commonly used photoresists include AZ125nXT, etc., and go through the steps of curing, baking, exposure, and development to obtain the bottom surface pattern of the micro-coaxial transmission line containing the micro-coaxial outer conductor and the first layer of the inner conductor.

[0072] Electroplating: Through the electroplating machine, the wafer with photolithographic pattern is electroplated with metal copper, and then the thickness of the metal copper and photoresist on the wafer surface is controlled to the target thickness by flattening. During the electroplating process, plating solution circulation, cathode swing, rotation and other methods can be used to assist the uniform thickness of the electroplated copper.

[0073] Wafer planarization: Common planarization methods include mechanical polishing, which uses aluminum oxide abrasives between the wafer polishing surface and the cast iron grinding wheel to grind at 40-100 rpm to initially flatten the copper layer and photoresist on the wafer surface. Chemical mechanical polishing is then used to further flatten the wafer until the thickness of the copper layer and photoresist reaches the target thickness.

[0074] Example 2

[0075] See also Figure 8-Figure 10 This embodiment provides a micro-coaxial transmission line. During the manufacturing process of the micro-coaxial transmission line, the substrate is peeled off by adopting the micro-coaxial transmission line substrate peeling method as described above to obtain the micro-coaxial.

[0076] Specifically, the main body of the micro-coaxial transmission line includes an outer conductor 100, an inner conductor 200 and an inner conductor support layer 300. The outer conductor 100 is arranged on the periphery of the inner conductor 200, and the inner conductor support layer 300 penetrates the inner conductor and the outer conductor.

[0077] The inner conductor support layer of the present application can be a SiC inner conductor support layer, so that the inner conductor support layer runs through the inner conductor and connects with the outer conductor, which can ensure that the inner conductor support layer is more solid and not easy to deform; and SiC is used as the inner conductor support layer, and its high hardness and wear resistance make the inner conductor support layer more solid and not easy to deform, thereby improving the overall structural stability of the micro-coaxial transmission line. In addition, during the manufacturing process of the micro-coaxial transmission line, the substrate can be reused, so that the micro-coaxial transmission line can have better cost-effectiveness in the market by saving materials and production costs.

[0078] Example 3

[0079] See also Figure 1-Figure 10 This embodiment provides a method for manufacturing a micro-coaxial transmission line with sapphire as an inner conductor support structure, so as to explain in detail the method for stripping the substrate of the micro-coaxial transmission line of the present application. The specific steps are as follows:

[0080] (1) Select a 4-inch fused silica glass wafer with a thickness of 1 mm, a total thickness variation (TTV) of less than 5 μm, and a surface roughness Ra of less than 0.5 nm.

[0081] (2) Using a temporary bonding adhesive process, the selected wafer substrate is bonded to an iron foil by vacuum hot pressing or other methods.

[0082] Among them, WLPTB4130 UV laser separation type temporary bonding adhesive was used, and the bonding adhesive was evenly spin-coated on the surface of the quartz glass wafer using a wafer spinner. The speed of the spin coating process was set to 1500rpm and the spin coating time was 60s. After the spin coating was completed, the wafer was preliminarily baked at 110℃ for 5min and then at 220℃ for 10min.

[0083] A pure iron foil of the same size as a 4-inch fused quartz glass wafer was selected, with a thickness of 0.2 mm and a surface roughness of Ra < 1 nm. WLPTB4130 UV laser separation type temporary bonding adhesive was also used, and the selected iron foil surface was evenly coated with a blade and placed in an oven for baking. The baking process was first baked at 110°C for 5 minutes, and then baked at 220°C for 10 minutes.

[0084] Then align the bonding adhesive surface of the fused quartz substrate wafer with the bonding adhesive surface of the iron foil and place them in a vacuum hot press bonding machine for bonding. During the bonding process, the pressure inside the vacuum hot press bonding machine is lower than 50Pa, the hot press temperature is 200℃, the bonding pressure is set to 0.3MPa, and the bonding time is 600s.

[0085] (3) The micro-coaxial device is prepared by using seed layer growth, thick resist photolithography, copper electroplating, planarization and other processes on the surface of the bonded iron foil. Specifically including:

[0086] A metal copper seed layer with a thickness of 0.5 μm was prepared on the surface of the iron foil by magnetron sputtering.

[0087] The micro-coaxial transmission line structure is prepared on the surface of the iron foil using thick resist photolithography, copper electroplating, planarization, photoresist release, seed layer corrosion and other processes commonly used in micro-coaxial structures.

[0088] (4) Using laser debonding process to separate the selected light-transmitting substrate and the iron foil. Specifically including:

[0089] The laser debonding process is used to scan the bonding adhesive between the wafer substrate and the iron foil to achieve debonding. After laser irradiation, the bonding adhesive loses its bonding viscosity. The laser beam uses an ultraviolet laser with a wavelength of 355nm and an energy of 200mj / cm 2 , scanning time 60s.

[0090] The residual bonding adhesive on the surface of the wafer substrate and the iron foil is cleaned and erased by using a cleaning agent corresponding to the WLPTB4130 bonding adhesive, and isopropyl alcohol is used to clean the substrate and the iron foil again to keep them clean.

[0091] (5) A selective corrosion solution is used to remove the iron foil, thereby completing the peeling of the micro-coaxial transmission line and the iron foil.

[0092] Specifically, the iron foil and the micro-coaxial transmission line with a metal copper structure that have not been completely separated are placed in a dilute sulfuric acid solution with a volume fraction of 40%, and immersed in it for more than 2 hours at room temperature to completely corrode and remove the iron foil, thereby completing the separation of the micro-coaxial transmission line and the wafer substrate.

[0093] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of this application.

[0094] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for stripping a micro-coaxial transmission line substrate, characterized in that: include: Obtain a wafer substrate; wherein the wafer substrate is made of a transparent material; bonding a metal sheet onto a wafer substrate; A micro-coaxial transmission line is prepared on a metal sheet, wherein the metal activity of the metal sheet is stronger than the metal activity of copper; The wafer substrate and the metal sheet are debonded by a laser debonding process, so that the wafer substrate and the metal sheet are separated.

2. The method for stripping a micro-coaxial transmission line substrate according to claim 1, characterized in that: After the wafer substrate is separated from the metal sheet, the method further includes: The metal sheet is removed by using a corrosive solution to complete the peeling of the micro-coaxial transmission line and the metal sheet.

3. The method for stripping a micro-coaxial transmission line substrate according to claim 1, characterized in that: The step of bonding a metal sheet on a wafer substrate comprises: Apply bonding glue on the wafer substrate and perform preliminary baking; Apply bonding glue on the metal sheet and bake it; The bonding adhesive on the wafer substrate is relatively fitted with the bonding adhesive on the metal sheet, and the substrate and the metal sheet are bonded by vacuum hot pressing.

4. The method for stripping a micro-coaxial transmission line substrate according to claim 3, characterized in that: The bonding glue is a laser separation type liquid bonding glue.

5. The method for stripping a micro-coaxial transmission line substrate according to claim 3, characterized in that: After the wafer substrate and the metal sheet are debonded by the laser debonding process, the method further includes: The residual bonding glue on the surface of the wafer substrate and the iron foil is cleaned and erased using a cleaning agent.

6. A method for stripping a micro-coaxial transmission line substrate according to any one of claims 1 to 5, characterized in that: The wafer substrate is a light-transmitting wafer, and the surface roughness Ra of the wafer substrate is less than 0.5 nm, the thickness is 0.5-1 mm, and the TTV is less than 10 μm.

7. A method for stripping a micro-coaxial transmission line substrate according to any one of claims 1 to 5, characterized in that: The size of the cross section of the metal sheet is the same as that of the cross section of the wafer substrate; the thickness of the metal sheet is 0.2 mm-0.5 mm.

8. A method for stripping a micro-coaxial transmission line substrate according to any one of claims 1 to 5, characterized in that: The method of preparing a micro-coaxial transmission line on a metal sheet comprises: The micro-coaxial transmission line is manufactured by using the processes of seed layer growth, thick resist photolithography, copper electroplating, and planarization; And the thickness of the seed layer is greater than 0.5 μm.

9. A micro-coaxial transmission line, characterized in that: During the manufacturing process, the substrate is peeled off by using the peeling method of the micro-coaxial transmission line substrate as described in any one of claims 1 to 9 to obtain the main body of the micro-coaxial transmission line.

10. The micro-coaxial transmission line according to claim 9, characterized in that: The main body of the micro-coaxial transmission line includes an outer conductor, an inner conductor and an inner conductor support layer. The outer conductor is arranged on the periphery of the inner conductor, and the inner conductor support layer penetrates the inner conductor and is connected to the outer conductor.

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