CN111455413B - Method for shortening micro-electroforming processing time - Google Patents

Method for shortening micro-electroforming processing time Download PDF

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Publication number
CN111455413B
CN111455413B CN202010459912.0A CN202010459912A CN111455413B CN 111455413 B CN111455413 B CN 111455413B CN 202010459912 A CN202010459912 A CN 202010459912A CN 111455413 B CN111455413 B CN 111455413B
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nickel
copper
layer
electroplating
target device
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CN111455413A (en
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丰伟
郑英彬
王颉
杨晴
唐彬
支钞
高彩云
孙强
张青芝
王旭光
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Institute of Electronic Engineering of CAEP
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Institute of Electronic Engineering of CAEP
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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D1/00—Electroforming
    • C25D1/003—3D structures, e.g. superposed patterned layers
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
    • C23F3/00—Brightening metals by chemical means
    • C23F3/04—Heavy metals
    • C23F3/06—Heavy metals with acidic solutions
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D1/00—Electroforming
    • C25D1/10—Moulds; Masks; Masterforms

Abstract

The invention provides a method for shortening micro-electroforming processing time, and belongs to the technical field of micro-electroforming processes. The method for shortening the micro-electroforming processing time comprises the steps of preparing a first photoetching plate, first nickel electroplating, first flattening, a second photoetching plate, second nickel electroplating, photoresist removing, copper electroplating, second flattening and copper removing on a substrate in sequence to obtain a target device. When the two-layer structure is prepared, the one-step electroplating process can be reduced, and the electroplating time is shortened; the time for the first flattening process is short, and the time for the second flattening process can be reduced by half, so that the total time for the flattening process is greatly shortened; meanwhile, the processing time is shortened, the probability of damage of products is reduced, and the yield of the products is improved. The results of the examples show that the production cycle of the product is shortened from 675h to 357h, the processing time is shortened by 47.1%, and the yield is improved from less than 5% to more than 90% by adopting the method of the invention.

Description

Method for shortening micro-electroforming processing time
Technical Field
The invention relates to the technical field of micro electroforming processes, in particular to a method for shortening micro electroforming processing time.
Background
The micro electroforming process is a new concept established on the basis of the traditional electroforming process, has the outstanding advantages of micro structure forming, complex structure forming, high precision, batch production and the like, can be regarded as the extension of the traditional electroforming technology on the basis of a micro machining die, and can also be regarded as the result of the development of the trailing film electroplating in the direction of the high aspect ratio, and can be divided into two stages with different properties: the first stage is to fill metal in the deep layer of the mask microstructure; the second stage is to deposit a thick metal film over the entire photoresist and metal structure surface for processing into a base of the die cast film.
When a traditional micro electroforming machining method is used for machining parts, only 1 layer can be machined in a circulating mode at each time, and the method mainly comprises the following steps: and sequentially performing glue coating, photoetching, nickel plating, glue film removal, copper plating and planarization on the silicon substrate to finish the processing of one layer. The traditional processing method has the advantages of long processing time, low actual qualified rate of products, difficult improvement, complex process, limitation on the efficiency of industrial production and improvement on the production cost.
Disclosure of Invention
Compared with the traditional method, the method for shortening the micro-electroforming processing time provided by the invention can reduce one-step electroplating process and shorten the electroplating time when preparing a two-layer structure, and is simple, easy to control the operation process and suitable for large-scale production.
In order to achieve the above object, the present invention provides the following technical solutions:
the invention provides a method for shortening micro-electroforming processing time, which comprises the following steps:
(1) preparing a first photoetching plate with a hollow structure on a substrate, then carrying out first nickel electroplating to fill the hollow structure of the first photoetching plate with nickel, and then carrying out first planarization to form a first composite layer on the surface of the substrate;
(2) preparing a second photoetching plate with a hollow structure on the first composite layer in the step (1), and then carrying out second nickel electroplating to fill the hollow structure of the second photoetching plate with nickel, so as to form a second composite layer on the surface of the first composite layer;
(3) performing photoresist removing treatment on the first composite layer in the step (1) and the second composite layer in the step (2), and forming a metal nickel layer with a hollow structure on the surface of the substrate;
(4) electroplating copper on the metal nickel layer in the step (3) to fill the hollow part of the metal nickel layer with copper, and forming a copper-nickel mixed metal layer on the surface of the substrate;
(5) carrying out secondary planarization on the copper-nickel mixed metal layer in the step (4) to obtain a precursor of the target device;
(6) and (5) carrying out copper removal treatment on the target device precursor obtained in the step (5) to obtain the target device.
Preferably, the step (5) further comprises, after the second planarization: when the number of layers of the target device is an even number greater than 2, repeating the steps (1) to (5) for more than 1 time according to the number of required layers to obtain a precursor of the target device; and (3) when the number of layers of the target device is an odd number greater than 3, repeating the steps (1) to (5) for more than 1 time according to the required number of layers, and then repeating the steps (1), (3), (4) and (5) once to obtain the precursor of the target device.
Preferably, the method for preparing the first photolithography plate in the step (1) and the second photolithography plate in the step (2) independently comprises spin coating and photolithography which are sequentially performed.
Preferably, the second planarization in step (5) adopts a chemical mechanical polishing method, and the polishing solution adopted by the chemical mechanical polishing method is a mixed solution of acetic acid and hydrogen peroxide.
Preferably, the volume ratio of the acetic acid to the hydrogen peroxide is (0.5-2): 5.
preferably, the solvent used in the decoppering treatment in step (6) includes ammonia water and NaClO2。
Preferably, the NaClO2The mass ratio of (A) to the volume ratio of ammonia water is as follows: (10-30) g:100 mL.
Preferably, the temperature of the copper removing treatment in the step (6) is less than or equal to 40 ℃.
Preferably, the decoppering treatment in step (6) is performed under ultrasonic vibration conditions.
Preferably, the power of the ultrasonic vibration is 20-60 KHz.
The invention provides a method for shortening micro-electroforming processing time, which comprises the following steps: preparing a first photoetching plate with a hollow structure on a substrate, then carrying out first nickel electroplating to fill the hollow structure of the first photoetching plate with nickel, and then carrying out first planarization to form a first composite layer on the surface of the substrate; preparing a second photoetching plate with a hollow structure on the first composite layer, and then carrying out second nickel electroplating to fill the hollow structure of the second photoetching plate with nickel, so as to form a second composite layer on the surface of the first composite layer; carrying out photoresist removing treatment on the first composite layer and the second composite layer to form a metal nickel layer with a hollow structure on the surface of the substrate; electroplating copper on the metal nickel layer to fill the hollow part of the metal nickel layer with copper, and forming a copper-nickel mixed metal layer on the surface of the substrate; carrying out secondary planarization on the copper-nickel mixed metal layer to obtain a precursor of the target device; and carrying out copper removal treatment on the precursor of the target device to obtain the target device. Compared with the traditional method, the method provided by the invention can reduce one-step electroplating process and shorten electroplating time when preparing the two-layer structure; when the planarization process is carried out, the time consumption of the planarization process is short because the first planarization process only has one metal, and the time consumption of the planarization process can be reduced by half compared with the conventional planarization process when the mixed metal layer planarization process is carried out in the second planarization process, so that the total time consumption of the planarization process is greatly shortened, and the production efficiency is greatly improved; meanwhile, the processing time is shortened, the probability of damage to products in the processing process is reduced, and the yield of the products is improved. The results of the embodiment show that the processing time and yield of the multilayer micro-gear transmission three-dimensional mechanism produced by the traditional micro-electroforming processing method and the new method are shortened from 675h to 357h, the processing time is shortened by 47.1%, and the yield is improved from less than 5% to more than 90%.
The method for shortening the micro-electroforming processing time is simple to operate, easy to control the operation process and suitable for large-scale production.
Drawings
FIG. 1 is a top view of a multi-layer micro-geared stereo set provided in example 1 and comparative example 1 of the present invention;
FIG. 2 is a front view of a multi-layer micro-geared three-dimensional mechanism provided in example 1 and comparative example 1 of the present invention;
FIG. 3 is a front three-axis side view of a multi-layer micro-geared stereo set provided in example 1 of the present invention and comparative example 1;
FIG. 4 is an exploded view of a multi-layer micro-gear transmission solid structure provided in example 1 and comparative example 1 of the present invention, with 5 layers;
FIG. 5 is a schematic view of a product after a first photolithography plate is prepared in step (1) of example 1 of the present invention;
FIG. 6 is a schematic view showing a product after the first nickel electroplating in step (1) of example 1 of the present invention;
FIG. 7 is a schematic view showing a product after the first planarization in step (1) of example 1 of the present invention;
FIG. 8 is a schematic view of a product after a second photolithography plate is prepared in step (2) of example 1 of the present invention;
FIG. 9 is a schematic view showing a product after the second nickel electroplating in step (2) of example 1 of the present invention;
FIG. 10 is a schematic view of a product after stripping in step (3) of example 1 of the present invention;
FIG. 11 is a schematic view showing a product after copper electroplating in step (4) of example 1 of the present invention;
FIG. 12 is a schematic view showing a product after the second planarization in step (5) of example 1 of the present invention;
FIG. 13 is a schematic view of a target device precursor in step (5) of example 1 of the present invention;
FIG. 14 is a schematic view of the product of decoppering in step (6) of example 1 of the present invention;
FIG. 15 is a schematic view of a product after preparing a first photolithographic plate in step (1) of comparative example 1 of the present invention;
FIG. 16 is a schematic view showing a product after nickel plating in step (2) of comparative example 1 according to the present invention;
FIG. 17 is a schematic view showing a product of the present invention after the removal of photoresist in step (3) of comparative example 1;
FIG. 18 is a schematic view showing a product after copper electroplating in step (4) of comparative example 1 according to the present invention;
FIG. 19 is a schematic view showing a product of comparative example 1 of the present invention after planarization in step (5);
FIG. 20 is a schematic view of a target device precursor in step (6) of comparative example 1 according to the present invention;
FIG. 21 is a schematic representation of the product of comparative example 1 of the present invention after decoppering in step (7).
Detailed Description
The invention provides a method for shortening micro-electroforming processing time, which comprises the following steps:
(1) preparing a first photoetching plate with a hollow structure on a substrate, then carrying out first nickel electroplating to fill the hollow structure of the first photoetching plate with nickel, and then carrying out first planarization to form a first composite layer on the surface of the substrate;
(2) preparing a second photoetching plate with a hollow structure on the first composite layer in the step (1), and then carrying out second nickel electroplating to fill the hollow structure of the second photoetching plate with nickel, so as to form a second composite layer on the surface of the first composite layer;
(3) performing photoresist removing treatment on the first composite layer in the step (1) and the second composite layer in the step (2), and forming a metal nickel layer with a hollow structure on the surface of the substrate;
(4) electroplating copper on the metal nickel layer in the step (3) to fill the hollow part of the metal nickel layer with copper, and forming a copper-nickel mixed metal layer on the surface of the substrate;
(5) carrying out secondary planarization on the copper-nickel mixed metal layer in the step (4) to obtain a precursor of the target device;
(6) and (5) carrying out copper removal treatment on the target device precursor obtained in the step (5) to obtain the target device.
The method comprises the steps of preparing a first photoetching plate with a hollow structure on a substrate, then carrying out first nickel electroplating to fill the hollow structure of the first photoetching plate with nickel, and then carrying out first planarization to form a first composite layer on the surface of the substrate.
The present invention is not particularly limited in the kind of the substrate, and a substrate known to those skilled in the art may be used. In the present invention, the substrate is preferably an oxygen-free copper substrate. The invention uses the oxygen-free copper substrate as the substrate, and can remove the substrate simultaneously in the copper removing process, thereby omitting the process of removing the substrate and reducing the time of processing parts.
In the invention, the pre-baking of the substrate is also included before the first photoetching plate with the hollow structure is prepared on the substrate. In the invention, the pre-drying temperature is preferably 100-150 ℃, and more preferably 120 ℃; the pre-drying time is selected to be 20-30 h, and more preferably 24 h.
In the invention, the preparation method of the first photolithography plate preferably comprises sequentially performing photoresist throwing and photolithography. In the invention, the spin coating speed is preferably 2000-3000 r/min, and more preferably 2500 r/min. In the invention, the glue used in the whirl coating is preferably SU8 glue, more preferably SU8-2150, SU8-2035 and SU 8-2050. In the invention, when the glue is SU8-2150, the thickness of the glue for forming the photoresist is preferably 100-150 μm, and more preferably 120-130 μm; when the photoresist is SU8-2035, the thickness of the photoresist is preferably 20-35 μm, more preferably 25-30 μm; when the photoresist is SU8-2050, the thickness of the photoresist is preferably 30-50 μm, and more preferably 35-45 μm. According to the invention, the photoetching plate is prepared by using SU8 glue, and the SU8 glue has higher strength after being cured, so that the deformation of the device caused by the deformation of the glue during multilayer preparation can be prevented, and the yield of products is improved.
In the invention, after the spin coating, the method preferably further comprises the steps of sequentially carrying out first heating, exposure, second heating and development on the spin coated product. In the invention, the first heating temperature is preferably 80-100 ℃, and more preferably 95 ℃; the first heating time is preferably 3-5 hours, and more preferably 4 hours. In the present invention, the exposure time is preferably 10 to 30s, and more preferably 20 s. In the invention, the second heating temperature is preferably 80-90 ℃, and more preferably 85 ℃; the second heating time is preferably 20-50 min, and more preferably 30 min. In the present invention, the developing time is preferably 20 to 50min, more preferably 25 to 40min, and most preferably 30 min. According to the invention, the parameters of the first photoetching plate preparation are limited in the range, so that the obtained photoetching plate has higher strength, the deformation of the device caused by the deformation of glue during multilayer preparation is prevented, and the yield of products is improved.
In the present invention, it is preferable that the cleaning of the first reticle is further performed before the first nickel electroplating. In the invention, the cleaning agent used for cleaning is preferably a sulfuric acid solution; the mass concentration of the sulfuric acid solution is preferably 5-20%, and more preferably 10%; the cleaning time is preferably 5 to 60s, more preferably 10 to 40s, and most preferably 20 s. The invention cleans the first photoetching plate, can remove impurities and ensure the quality of a target device.
In the invention, the speed of the first electroplating nickel is preferably 5-30 μm/h, more preferably 10-20 μm/h, and most preferably 15 μm/h; the time of the first nickel electroplating is preferably 5-10 hours, and more preferably 7 hours. The invention controls the speed and time of the first electroplating nickel in the range, and can ensure that the metal nickel completely fills the hollow structure of the first photoetching plate.
In the present invention, the first planarization preferably includes rough grinding and polishing performed in this order; the instrument used for the first planarization is preferably an MP precision grinder. The invention has no special limitation on the specific parameters of the first planarization, and the first composite layer obtained after the first planarization is ensured to be flat and bright.
After the first composite layer is obtained, a second photoetching plate with a hollow structure is prepared on the first composite layer, then second nickel electroplating is carried out, the hollow structure of the second photoetching plate is filled with nickel, and a second composite layer is formed on the surface of the first composite layer.
In the invention, the preparation method of the second photolithography plate preferably includes spin coating and photolithography which are sequentially performed. The photoresist stripping and photolithography operations are not particularly limited in the present invention, and the photoresist stripping and photolithography technical solutions known to those skilled in the art can be adopted. In the present invention, the photoresist throwing and the photolithography are preferably the same as the method for preparing the first photolithography plate.
In the invention, after the spin coating, the method preferably further comprises the steps of sequentially carrying out first heating, exposure, second heating and development on the spin coated product. In the present invention, the first heating, the exposure, the second heating and the development are preferably the same as those of the first reticle.
In the present invention, it is preferable that the cleaning of the second reticle is further performed before the second nickel electroplating, and the cleaning operation is preferably the same as the cleaning before the first nickel electroplating.
In the present invention, the second electroplating nickel is preferably the same as the first electroplating nickel in terms of parameters.
After the second composite layer is formed, the first composite layer and the second composite layer are subjected to photoresist removing treatment, and a metal nickel layer with a hollow structure is formed on the surface of the substrate.
In the invention, the photoresist removing treatment preferably uses a microwave plasma cleaning machine, and the rate of the photoresist removing treatment is preferably 1-3 μm/min, and more preferably 2 μm/min.
After the metal nickel layer with the hollow structure is formed, the invention carries out copper electroplating on the metal nickel layer, so that the hollow part of the metal nickel layer is filled with copper, and a copper-nickel mixed metal layer is formed on the surface of the substrate.
In the present invention, it is preferable that the step of cleaning the metallic nickel layer is further included before the step of performing the copper electroplating. In the invention, the cleaning agent used for cleaning is preferably a sulfuric acid solution; the mass concentration of the sulfuric acid solution is preferably 5-20%, and more preferably 10%; the cleaning time is preferably 5 to 60 seconds, more preferably 10 to 40 seconds, and most preferably 20 seconds. The invention cleans the metal nickel layer, which can ensure that only electroformed metal nickel is left on the substrate.
In the invention, the speed of the copper electroplating is preferably 5-30 μm/h, more preferably 10-20 μm/h, and most preferably 15 μm/h; the time for electroplating copper is preferably 5-15 h, and more preferably 10 h.
After the copper-nickel mixed metal layer is formed, the copper-nickel mixed metal layer is flattened for the second time to obtain a precursor of the target device.
In the present invention, the second planarization is preferably performed by a chemical mechanical polishing method, and the polishing liquid preferably used in the chemical mechanical polishing method is preferably a mixed liquid of acetic acid and hydrogen peroxide.
In the invention, the volume ratio of acetic acid to hydrogen peroxide is preferably (0.5-2): 5, more preferably 1: 5. The method uses the mixed solution of acetic acid and hydrogen peroxide as the grinding liquid to carry out chemical mechanical polishing, and can lead the corrosion rate of the grinding liquid to copper and nickel to be the same by controlling the volume ratio of the acetic acid to the hydrogen peroxide within the range, thereby ensuring the smooth surface of the mixed metal of copper and nickel in the polishing process, improving the polishing rate, greatly reducing the processing time, improving the yield of products, simultaneously avoiding the corrosion to equipment by using the hydrogen peroxide, and reducing the generation cost.
In the invention, the dosage relationship between the grinding liquid and the grinding material used in the polishing process is preferably that 20-30 mL of hydrogen peroxide and 1-5 mL of acetic acid are added into 1L of grinding material.
The sources of acetic acid and hydrogen peroxide used in the chemical mechanical polishing method are not particularly limited, and the method can be realized by adopting a commercially available product.
The specific preparation method of the polishing slurry is not particularly limited in the present invention, and a mixing method known to those skilled in the art may be used.
In the present invention, it is preferable that the second planarization further includes: when the number of layers of the target device is an even number greater than 2, repeating the steps (1) to (5) for more than 1 time according to the number of required layers to obtain a precursor of the target device; and (3) when the number of layers of the target device is an odd number greater than 3, repeating the steps (1) to (5) for more than 1 time according to the required number of layers, and then repeating the steps (1), (3), (4) and (5) once to obtain the precursor of the target device. Specifically, in the embodiment of the present invention, when the number of layers of the target device is 3, repeating steps (1) to (5)1 time, and then repeating steps (1), (3), (4), and (5) once to obtain the target device precursor; when the number of layers of the target device is 4, repeating the steps (1) to (5) for 2 times to obtain a precursor of the target device; and (3) when the target device is 5 layers, repeating the steps (1) to (5) for 2 times, and then repeating the steps (1), (3), (4) and (5) once to obtain the target device precursor. The invention limits the processing steps within the range, can ensure that the processing technology can process workpieces with different layers, has wide application range, and is suitable for large-scale popularization of industrial production.
After the target device precursor is obtained, the method carries out copper removal treatment on the target device precursor to obtain the target device. In the present invention, the solvent used for the decoppering treatment preferably includes aqueous ammonia and NaClO2. In the present invention, the NaClO is2The mass to ammonia volume ratio of (a): (10-30) g:100mL, more preferably 20 g:100 mL; the mass concentration of the ammonia water is preferably 20-30%, and more preferably 25%. In the invention, the temperature of the copper removal treatment is preferably less than or equal to 40 ℃, and more preferably 30-40 ℃; the copper removing treatment is preferably carried out under the ultrasonic vibration condition, and the power of the ultrasonic vibration is preferably 20-60 KHz, and more preferably 40 KHz. The invention limits the technological parameters of the copper removing treatment in the range, can accelerate the copper removing speed, does not influence the metallic nickel, reduces the processing time and improves the yield of the device.
In an embodiment of the present invention, as shown in fig. 1 to 4, when the workpiece to be processed is a multi-layer micro gear transmission stereo mechanism, the method for shortening the micro electroforming processing time preferably includes:
(1) preparing a first photoetching plate with a hollow structure on a substrate, then carrying out first nickel electroplating to fill the hollow structure of the first photoetching plate with nickel, and then carrying out first planarization to form a first composite layer on the surface of the substrate;
(2) preparing a second photoetching plate with a hollow structure on the first composite layer in the step (1), and then carrying out second nickel electroplating to fill the hollow structure of the second photoetching plate with nickel, so as to form a second composite layer on the surface of the first composite layer;
(3) performing photoresist removing treatment on the first composite layer in the step (1) and the second composite layer in the step (2), and forming a metal nickel layer with a hollow structure on the surface of the substrate;
(4) electroplating copper on the metal nickel layer in the step (3) to fill the hollow part of the metal nickel layer with copper, and forming a copper-nickel mixed metal layer on the surface of the substrate;
(5) carrying out secondary planarization on the copper-nickel mixed metal layer in the step (4);
(6) repeating the steps (1) to (5) for 1 time, and then repeating the steps (1), (3), (4) and (5) once to obtain a precursor of the multilayer micro-gear transmission three-dimensional mechanism;
(7) and (4) carrying out copper removal treatment on the target device precursor obtained in the step (6) to obtain the multilayer micro-gear transmission three-dimensional mechanism.
Compared with the traditional method, the method provided by the invention can reduce one-step electroplating process and shorten electroplating time when preparing the two-layer structure; when the planarization process is carried out, the time consumption of the planarization process is short because the first planarization process only has one metal, and the time consumption of the planarization process can be reduced by half compared with the conventional planarization process when the mixed metal layer planarization process is carried out in the second planarization process, so that the total time consumption of the planarization process is greatly shortened, and the production efficiency is greatly improved; meanwhile, the processing time is shortened, the probability of damage to products in the processing process is reduced, and the yield of the products is improved.
The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
A multi-layer micro-gear transmission three-dimensional mechanism is processed, as shown in the attached figure 1, and the unit is micrometer.
The size of the multilayer micro-gear three-dimensional mechanism is 4000 micrometers multiplied by 500 micrometers, two coaxial gears are bridged on two sides of the bracket, the two gears on the same side are meshed with each other, the gears coaxially connected rotate synchronously, and the gears on the same side realize transmission. The diameter of the addendum circle was 1200 μm, and the processing was performed by decomposing the addendum circle into 5 layers in the Z-axis direction, each layer having a thickness of 100. mu.m. The plan view is shown in fig. 1, the front view is shown in fig. 2, the front three-axis view is shown in fig. 3, and the exploded view into 5 layers is shown in fig. 4.
(1) Using a 4-inch oxygen-free copper substrate as a substrate, pre-baking the substrate at 120 ℃ for 24h, then using SU8-2150 glue to spin glue, wherein the spin glue rate is 2500 rpm, then heating for the first time at 95 ℃ for 4h, then exposing for 20s, heating for the second time at 85 ℃ for 30min, developing for 30min, and forming a first photoetching plate with a hollow structure, wherein the thickness of the SU8-2150 glue is 120 mu m, as shown in FIG. 5; then, carrying out an electroplating nickel process, cleaning the glue film obtained in the step (1) for 20s by using a sulfuric acid solution with the mass concentration of 10%, then carrying out electroplating nickel, controlling the electroplating nickel speed to be 15 mu m/h, controlling the electroplating nickel speed to be 7h and about 105 mu m in total, and enabling the thickness to be flush with the SU8 glue, so that the hollow structure of the first photoetching plate is filled with nickel, as shown in FIG. 6; using an MP precision grinder to perform a planarization process on the nickel and photoresist mixed layer, sequentially performing rough grinding and polishing, grinding the nickel and photoresist mixed layer to a predetermined thickness, and forming a first composite layer on the surface of the substrate, as shown in fig. 7.
(2) Performing photoresist throwing and photoetching on the first composite layer again to form a second photoetching plate with a hollow structure, as shown in fig. 8; and (3) performing an electroplating nickel process to fill the hollow part of the adhesive film with nickel to form a second composite layer, as shown in fig. 9, wherein the process parameters are the same as those in the step (1).
(3) And (3) carrying out photoresist removing treatment on the first composite layer and the second composite layer by using a microwave plasma cleaning machine, wherein the photoresist removing speed is 2 min/mum, and forming a metal nickel layer with a hollow structure on the surface of the substrate after removing the adhesive film, as shown in figure 10.
(4) And (3) carrying out a copper electroplating process on the metal nickel layer, and cleaning the metal nickel layer for 20s by adopting a sulfuric acid solution with the mass concentration of 10%, wherein only electroformed metal nickel is left on the substrate. Using electroplated copper as sacrificial layer, the thickness of electroplated copper layer is equal to that of metal nickel, the electroplating rate is 15 μm/h, and the electroplating time is 10h, and reaches 150 μm, so as to form copper-nickel mixed metal layer, as shown in fig. 11.
(5) A flattening process is carried out on the copper-nickel mixed metal layer by using an MP precision grinder, acetic acid and hydrogen peroxide are prepared into a mixed solution as a grinding solution according to the proportion of 1:5, in terms of per liter, 25mL of hydrogen peroxide and 5mL of acetic acid are added into 1L of grinding material, and coarse grinding and polishing are carried out in sequence until the copper-nickel mixed metal layer is flat and bright, so that the copper-nickel mixed metal layer is ground to a preset thickness, as shown in figure 12; and (3) repeating the steps 1 to 8 to finish the processing of 2 layers, and repeating the steps 1, 2, 6, 7 and 8 to process 1 layer, so that all layers are processed to obtain the precursor of the target device, as shown in fig. 13.
(6) Copper was removed using a copper etchant, 20g of NaClO2The solid was dissolved in 100mL of 25% ammonia water to obtain a copper etchant, and the workpiece was placed in the copper etchant, and the copper etchant was heated to 35 ℃ while applying 40kHz ultrasonic vibration to obtain the target device, as shown in fig. 14.
Comparative example 1
The multilayer micro-gear transmission three-dimensional mechanism in example 1 was processed using a conventional micro-electroforming processing method:
(1) using a 4-inch oxygen-free copper substrate as a substrate, pre-baking the substrate at 120 ℃ for 24h, then using SU8-2150 glue to spin glue, wherein the speed of the substrate is 2500 rpm in the spin glue process, then heating for the first time at 95 ℃ for 4h, then exposing for 20s, heating for the second time at 85 ℃ for 30min, developing for 30min, and the thickness of the SU8-2150 glue is 120 mu m, so as to form a first photoetching plate with a hollow structure, as shown in FIG. 15.
(2) And (3) carrying out an electroplating nickel process, cleaning the glue film obtained in the step (1) for 20s by using a sulfuric acid solution with the mass concentration of 10%, then carrying out electroplating nickel, controlling the electroplating nickel speed to be 15 mu m/h, controlling the electroplating nickel speed to be 7h and about 105 mu m in total, and enabling the thickness to be flush with that of SU8 glue, so that the hollow structure of the first photoetching plate is filled with nickel, as shown in figure 16.
(3) Using a microwave plasma cleaning machine to carry out photoresist removing treatment, wherein the photoresist removing speed is 2 min/mum, and obtaining the metal nickel layer after removing the glue film, as shown in fig. 17.
(4) And (3) carrying out a copper electroplating process on the metal nickel layer, and cleaning the metal nickel layer for 20s by adopting a sulfuric acid solution with the mass concentration of 10%, wherein only electroformed Ni is remained on the substrate. Using electroplated copper as the sacrificial layer, the thickness of the electroplated copper layer is equal to that of Ni, the electroplating rate is 15 μm/h, and the electroplating time is 10h, reaching 150 μm, to form the copper-nickel mixed metal layer, as shown in fig. 18.
(5) The MP precision grinder is used to perform a planarization process on the cu-ni mixed metal layer, and the cu-ni mixed metal layer is ground to a predetermined thickness by performing a coarse grinding and polishing in sequence to achieve a smooth and bright surface, so as to complete a layer processing and form a first composite layer, as shown in fig. 19.
(6) The processing of the remaining 4 layers is completed by repeating the steps (1) to (5), and the target device precursor is obtained, as shown in fig. 20.
(7) The use of the catalyst employs 20g of solid NaClO2And 100mL of an aqueous ammonia mixture having a mass concentration of 25% as a copper removal reagent, and removing copper to obtain the target apparatus, as shown in FIG. 21.
Further description of the processes of example 1 and comparative example 1 with the use of a multi-layer micro-gear transmission: compared with the traditional method, the new method has the advantages that one-time electroplating is less, the time is shortened by 10 hours, because two layers of glue films need to be removed in the glue removing process, the glue removing time is increased by 2 hours, the first planarization process only has one metal, the process time is 3 hours, the mixed metal layer planarization process time is 40 hours, the total planarization process time is shortened by 37 hours, the new method for processing two layers is shortened by 48 hours and 18.3 percent compared with the traditional method, and the results are shown in table 1.
Table 1 comparison of the time required to process 2 layers for example 1 and comparative example 1
Figure BDA0002510585430000111
When the processing is carried out, the patterns on the two adjacent sides can be processed at one time, and if the patterns are complex, one layer is processed at one time, so that the processing time can be shortened, and the yield can be ensured.
The method provided by the invention adopts a chemical mechanical polishing method in the planarization process of the copper-nickel mixed metal layer, adopts new grinding fluid, and shortens the planarization process time of the mixed metal layer in the multi-layer micro-gear transmission three-dimensional mechanism from 40 hours to 24 hours, which is about 40 percent shorter.
The effect of ultrasonic vibration and heating on the decoppering rate is shown in table 2. It can be known through table 2 that ultrasonic vibration and heating can both increase the speed of copper removal and do not harm the structure, can promote 67.7% with getting rid of the copper speed through ultrasonic vibration, and heating 10 ℃ can promote 161% with getting rid of the copper speed, and ultrasonic vibration and heating 10 ℃ do not have obvious influence to the corrosion rate of nickel.
TABLE 2 influence of ultrasonic vibration and heating on the copper removal rate
Figure BDA0002510585430000121
The copper removing process time of the multilayer micro-gear three-dimensional transmission mechanism is shortened from 60 hours under normal temperature and pressure to 24 hours.
Table 3 shows the processing time and yield of the multilayer micro-gear transmission three-dimensional mechanism produced by the comparative example 1 and the example 1, and it can be seen from the table that the production period is shortened from 675h to 357h, the processing time is shortened by 47.1%, and the yield is improved from less than 5% to more than 90%.
Table 3 comparison of production time and yield for processing multilayer micro-gear transmission three-dimensional mechanism in comparative example 1 and example 1
Production cycle Yield of
Comparative example 1 675h <5％
Example 1 357h >90％
From the above embodiments, compared with the processing time and yield of the multilayer micro gear transmission three-dimensional mechanism produced by the traditional micro electroforming method, the method for shortening the micro electroforming processing time provided by the invention has the advantages that the production period is shortened from 675h to 357h, the processing time is shortened by 47.1%, the yield is improved from less than 5% to more than 90%, the method is simple to operate, the operation process is easy to control, and the method is suitable for large-scale production.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims (6)

1. A method for shortening micro electroforming processing time comprises the following steps:
(1) preparing a first photoetching plate with a hollow structure on a substrate, then carrying out first nickel electroplating to fill the hollow structure of the first photoetching plate with nickel, and then carrying out first planarization to form a first composite layer on the surface of the substrate;
(2) preparing a second photoetching plate with a hollow structure on the first composite layer in the step (1), and then carrying out second nickel electroplating to fill the hollow structure of the second photoetching plate with nickel, so as to form a second composite layer on the surface of the first composite layer;
(3) performing photoresist removing treatment on the first composite layer in the step (1) and the second composite layer in the step (2), and forming a metal nickel layer with a hollow structure on the surface of the substrate;
(4) electroplating copper on the metal nickel layer in the step (3) to fill the hollow part of the metal nickel layer with copper, and forming a copper-nickel mixed metal layer on the surface of the substrate;
(5) carrying out secondary planarization on the copper-nickel mixed metal layer in the step (4) to obtain a precursor of the target device; and the second planarization adopts a chemical mechanical polishing method, the grinding liquid adopted by the chemical mechanical polishing method is a mixed liquid of acetic acid and hydrogen peroxide, and the volume ratio of the acetic acid to the hydrogen peroxide is (0.5-2): 5;
(6) performing copper removal treatment on the target device precursor obtained in the step (5) to obtain a target device; the solvent used in the decoppering treatment consists of ammonia water and NaClO2Composition of said NaClO2The mass ratio of (A) to the volume ratio of ammonia water is as follows: (10-30) g:100 mL; the mass concentration of the ammonia water is 20-30%.
2. The method of claim 1, wherein the step (5) further comprises, after the second planarization: when the number of layers of the target device is an even number greater than 2, repeating the steps (1) to (5) for more than 1 time according to the number of required layers to obtain a precursor of the target device; and (3) when the number of layers of the target device is an odd number greater than 3, repeating the steps (1) to (5) for more than 1 time according to the required number of layers, and then repeating the steps (1), (3), (4) and (5) once to obtain the precursor of the target device.
3. The method according to claim 1 or 2, wherein the first photolithography plate in step (1) and the second photolithography plate in step (2) are prepared by a method independently comprising photoresist throwing and photolithography sequentially.
4. The method according to claim 1, wherein the temperature of the decoppering treatment in step (6) is less than or equal to 40 ℃.
5. The method according to claim 1, wherein the decoppering treatment in step (6) is performed under ultrasonic vibration conditions.
6. The method according to claim 5, wherein the power of the ultrasonic vibration is 20 to 60 KHz.
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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1312843A (en) * 1998-06-26 2001-09-12 卡伯特微电子公司 Chemical mechanical polishing slurry useful for copper/tantalum substrates
CN1583543A (en) * 2004-06-03 2005-02-23 上海交通大学 Method for integral micromachining multilayer composite structure
CN105624679A (en) * 2014-11-04 2016-06-01 中国科学院苏州纳米技术与纳米仿生研究所 Copper-etching solution, preparation method and application thereof, and copper etching method

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1312843A (en) * 1998-06-26 2001-09-12 卡伯特微电子公司 Chemical mechanical polishing slurry useful for copper/tantalum substrates
CN1583543A (en) * 2004-06-03 2005-02-23 上海交通大学 Method for integral micromachining multilayer composite structure
CN105624679A (en) * 2014-11-04 2016-06-01 中国科学院苏州纳米技术与纳米仿生研究所 Copper-etching solution, preparation method and application thereof, and copper etching method

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