CN113463054B

CN113463054B - Full magnetron sputtering multilayer composite metallization method for dielectric filter

Info

Publication number: CN113463054B
Application number: CN202110779476.XA
Authority: CN
Inventors: 周大雨; 孙纳纳; 秦广宇; 刘卓
Original assignee: Chongqing Kangyiqing Technology Co ltd; Dalian University of Technology
Current assignee: Chongqing Kangyiqing Technology Co ltd; Dalian University of Technology
Priority date: 2021-07-09
Filing date: 2021-07-09
Publication date: 2022-08-09
Anticipated expiration: 2041-07-09
Also published as: CN113463054A

Abstract

A full magnetron sputtering multilayer composite metallization method for a dielectric filter belongs to the technical field of communication. Firstly, cleaning a substrate by a wet method, drying the substrate, then placing the substrate into a vacuum chamber, and carrying out bombardment treatment on the substrate by adopting plasma; secondly, depositing high-activity metal or transition metal compound as an adhesion layer by magnetron sputtering under the condition of not departing from vacuum; thirdly, under the condition of not departing from vacuum, depositing a metal film on the surface of the adhesion layer by adopting a magnetron sputtering method to be used as a signal transmission conductor layer; and finally, continuing magnetron sputtering on the surface of the signal transmission layer to grow an anti-oxidation protection and welding layer. All the film layers are finished by magnetron sputtering; the ionization rate of Ar gas and metal atoms can be greatly improved by adopting high-power pulse magnetron sputtering under the distribution of an unbalanced magnetic field; by applying a magnetic field or bias voltage and the like on the sample table, the problems of low coverage rate, poor uniformity and the like of the coating in the hole in the common balanced magnetron sputtering technology can be solved; the production cost is reduced, and the sputtering time is saved.

Description

Full magnetron sputtering multilayer composite metallization method for dielectric filter

Technical Field

The invention belongs to the technical field of communication, and relates to a full magnetron sputtering multilayer composite metallization method for a dielectric filter.

Background

Today, when 5G technology is rapidly developed, a certain number of 5G base stations must be established to clear signals, and a filter is used as one of core devices of a radio frequency unit and has the functions of eliminating interference clutter, enabling useful signals to pass through without attenuation as much as possible and attenuating useless signals as much as possible. The base material of the dielectric filter is low-loss ceramic or plastic, and the base body is provided with an isolation groove, a coupling groove, a frequency adjusting blind hole, a coupling adjusting blind hole, an input electrode blind hole, an output electrode blind hole and the like, wherein the diameter of the blind hole is about 2-3mm, and the depth of the blind hole is about 2-4 mm. For the filter, no matter the substrate is ceramic or plastic, the transmission and the conduction of electromagnetic signals are realized by a metal layer on the surface, and the quality of the metal coating directly influences key performance indexes such as the Q value, the reliability, the weldability and the like of the dielectric filter. Silver has the advantages of excellent conductivity, good thermal stability, strong weldability and the like, and is a surface metallization material of a dielectric filter mainly adopted at present. The filter surface metallization method is many, and mainly includes electroplating, chemical plating, screen printing sintering, metal spraying, physical vapor deposition and the like.

The film layer generated by the electroplating process has high speed and high purity, but the process consumes a large amount of resources such as water, electricity, metal and the like, and generates a large amount of solid wastes, acid gases, heavy metal ion wastewater and the like to pollute the environment. Chemical plating is mainly used for preparing metal electrodes such as nickel, copper and the like in industrial production at present, the obtained electrode has the same performance as silver, and the chemical plating has the advantages of low cost, wide application range of matrix, good uniform plating and deep plating capability and the like. However, a large amount of heavy metal solutions such as tin, palladium and the like are easily generated in the coarsening, sensitization and activation treatment processes in the early stage of chemical plating, and the environment is polluted. The screen printing belongs to a silver burning and infiltrating process, namely, silver paste is coated on the surface of a matrix, and silver oxide in the silver paste is reduced into silver and infiltrated into the surface of the matrix after sintering. The process has the advantages of high production efficiency, good silver layer binding force, high surface quality and stable insertion loss, but has the problems of serious slurry waste, high cost, easy residue of sintering aids in filter holes and the like. The metal spraying method is to form a metal coating layer by using plasma spraying technology by atomized spraying or vacuum deposition of molten metal. Plasma spraying has been applied to ceramic metallization in recent years due to low equipment investment, but the adoption of the method can cause more waste of electrode materials and is generally only used for base metal spraying. In addition, when the metal dust concentration is high, explosion is liable to occur, and the risk is high. Physical Vapor Deposition (PVD) is a technique of vaporizing a material source into gaseous atoms, molecules, or partially ionizing them into ions under vacuum, and depositing a thin film on a substrate surface by a low-pressure gas or plasma process, and mainly includes two major categories, vacuum evaporation and sputter coating. The kinetic energy of particles escaping from the evaporation source by the vacuum evaporation method is low (about a few tenths to a few eV), so that the bonding force between the metal film layer and the ceramic is poor, and the electrode is easy to fall off; meanwhile, the problems of poor step coverage of the deposited film and the like can also be caused. Magnetron sputtering is to obtain kinetic energy to escape from target material atoms due to impact, and deposit the kinetic energy on the surface of a substrate to form a film. The film prepared by the process has high quality, good density, high adhesive force, strong thickness controllability, no pollution to the environment, low energy consumption and wide application in the preparation of various electronic devices. Compared with the evaporation process, the energy obtained by the bombarded atoms/atomic groups on the target material in the magnetron sputtering is high, the mobility is increased, and the step coverage capability is enhanced. However, in the conventional and balanced magnetron sputtering technique, the ionization rate of target atoms is generally lower than 10%, most of the target atoms reaching the substrate are neutral atoms, and the diffraction performance of the target atoms is poor and cannot meet the requirement of uniform coating in a hole with a high aspect ratio of a dielectric filter. This is due to the shadow effect, the film thickness at the bottom and sidewalls of the hole is much lower than the thickness of the grown film on the flat surface; meanwhile, the thicknesses of the side wall and the bottom are greatly different, the film of the side wall grows obliquely, the adhesive force and the density are poor, and the performance and the reliability of the device are seriously influenced. In order to improve the coverage rate and uniformity of the coating film in the hole, a special magnetron sputtering technology is firstly adopted to greatly improve the ionization rate of Ar gas and metal atoms; furthermore, by applying a magnetic field or bias voltage and the like on the sample stage, the diffraction of ions is improved, the secondary sputtering deposition effect is generated, the growth of the film in the hole is redistributed, and the step coverage rate is improved; further, the diffusion and migration capacity of metal atoms/ions is increased by increasing the deposition temperature of the film, and finally the thickness and distribution uniformity of the film at the bottom and on the side wall of the hole are improved.

In dielectric filter metallization, Ag has a low theoretical resistivity (1.47-1.62 μ Ω. cm), and is the metal material mainly used at present, but its manufacturing cost is high. The theoretical resistivity of Cu and Al is 1.678 and 2.65 mu omega-cm respectively, the difference of the conductivity of Cu and Al is not great, and the requirement of a dielectric filter on the high conductivity of a metal layer can be met. In the aspect of interface properties of ceramic and metal contact, when a metal (such as Cu, Au, Ag, Pd and the like) occupied by d shell electrons is adopted, the interface shows rectification characteristics; with metals having vacancies in the d-shell electrons (e.g., Ti, Ta, Cr, etc.), the interface tends to form an ohmic contact. In order to reduce the contact resistance between the ceramic and the metal, it is preferable to use a metal such as Ta, Cr, or Ti to form an ohmic contact between the ceramic and the metal interface. In addition, in order to improve the adhesion of the electrode film, means such as cleaning and activating the surface of the substrate or increasing the sputtering temperature can be adopted; an intermediate transition layer can also be introduced, namely, high-activity metals such as Cr, Ti, Cu, A1, Ni and the like are selected as adhesion layers to be firstly plated on the substrate, and the adhesion of the metal plating layer is increased by forming chemical bonding between the adhesion layers and the substrate. The metallized dielectric filter needs to be embedded in the operating circuit, so the solderability of the electrode layer, i.e. good wetting between the metal plating and the solder, must also be considered. Welding is a complex process accompanied by heating, melting, crystallization, phase change, chemical reaction, and the like. If the welding resistance of the metal film layer is not good, namely serious problems of oxidation, porcelain leakage, cracking and the like occur during welding, the electromagnetic performance and the reliability of components are also poor. Therefore, the metal coating to be deposited must also be considered as effective in blocking the high temperature solder erosion during soldering. Ag has good welding performance but weak erosion resistance, a thin Ag layer cannot withstand long-time high-temperature brazing, porcelain leakage and cracking easily occur, and Cu, Ni, Ti and Cr can be used as candidate metals for erosion resistance.

In summary, the metallization of the 5G base station dielectric filter provides the requirements of high coverage and high uniformity of the plated film in the hole with high aspect ratio, and also has strict requirements on the conductivity of the metal plating layer, the interface characteristics of the dielectric ceramic and the metal, the weldability and the anti-corrosion performance of the metal plating layer, and the like, which are difficult to satisfy by adopting the traditional equilibrium magnetron sputtering technology to prepare the single-layer electrode film. Therefore, the invention provides a multi-layer composite metallization and sputtering technical scheme of an adhesion layer/a signal transmission conductor layer/an anti-oxidation protection and welding layer. By adopting a magnetron sputtering process with high ionization rate and high surface atom diffusion rate, Cr, Ti, Cu, A1, Ni, Ta, Mo and other high-activity metals with the thickness less than 200nm and WN, TiN, TaN, TiW and other transition metal compounds are deposited on the surface of the medium after the plasma bombardment treatment to be used as an adhesion layer; then continuing to grow and prepare metal films of Cu, Al and the like with the thickness of 2-4 mu m as a signal transmission conductor layer; films of Ag, beta-Sn, Ag-Cu, Pb-Sn, Sn-Ag alloy and the like with the thickness less than 1 mu m are continuously grown to be used as an anti-oxidation protection layer and a welding layer. The method adopts cheap Cu and Al to replace Ag to serve as signal transmission conductor layers, greatly reduces the manufacturing cost of the dielectric filter, adopts magnetron sputtering to finish all film layers, has consistent and simple and feasible process, simultaneously obtains high film density, strong adhesive force and high step coverage rate by a special magnetron sputtering process, and can ensure the reliability of devices and the coverage rate and uniformity of film coating in holes with high depth-to-width ratio.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a full magnetron sputtering multilayer composite metallization method for a dielectric filter.

The technical scheme adopted by the invention is as follows:

a dielectric filter full magnetron sputtering multilayer composite metallization method, said method comprises carrying on the wet process to the basal body and washing at first, put into vacuum chamber after drying, use plasma body to carry on the bombardment treatment to the basal body; secondly, performing magnetron sputtering deposition on Cr, Ti, Cu, A1, Ni, Ta, Mo and other high-activity metals or WN, TiN, TaN, TiW and other transition metal compounds as an adhesion layer under the condition of not departing from vacuum; thirdly, depositing metal films such as Cu, Al and the like on the surface of the adhesion layer by adopting a magnetron sputtering method under the condition of not departing from vacuum to serve as a signal transmission conductor layer; finally, films of Ag, beta-Sn, Ag-Cu, Pb-Sn, Sn-Ag alloy and the like are continuously grown on the surface of the signal transmission layer by magnetron sputtering to be used as an anti-oxidation protection and welding layer. The method comprises the following specific steps:

the method comprises the following steps: the dielectric filter 5 is cleaned by a wet process to remove organic matter, metal particles and other impurities on the surface.

Step two: surface treatment of dielectric filter 5 substrate

Placing the dielectric filter processed in the step one in a vacuum chamber, and keeping the background vacuum degree less than or equal to 5 x 10 ^-4 Pa, working pressure of 0.3-2Pa, Ar flow of 40-200sccm, and radio frequency power density of 5-10W/cm ² Under the condition, the substrate is bombarded by the plasma for 5-30min, surface pollutants are removed, broken bonds and dangling bonds are generated, so that the metal of the subsequently deposited adhesion layer can be chemically bonded with the surface of the matrix, and the adhesion between the metal and the matrix is improved.

Step three: depositing an adhesion layer

The vacuum degree of the background is less than or equal to 5 x 10 ^-4 Pa, working pressure of 0.3-0.5Pa, Ar flow of 40-200sccm, and power density of 0.01-10kW/cm ² And depositing Cr, Ta, Mo, Ti, Cu, A1 and Ni high-activity metal or WN, TiN and TaN transition metal nitride films with the thickness of 50-200nm on the surface of the dielectric filter substrate treated in the step two as the adhesion layer 6 by adopting a special magnetron sputtering technology at the substrate temperature of Room Temperature (RT) -300 ℃.

Step four: depositing a signal transmission conductor layer

The vacuum degree of the background is less than or equal to 5 x 10 ^-4 Pa, working pressure of 0.3-1.5Pa, Ar flow of 40-200sccm, and power density of 0.01-10kW/cm ² And depositing metal films with the thickness of 2-4 mu m, such as Cu, Al and the like on the surface of the dielectric filter base treated in the third step by adopting the magnetron sputtering technology of the third step at the substrate temperature of Room Temperature (RT) -300 ℃ to serve as a signal transmission conductor layer 7.

Step five: depositing an oxidation resistant protective and solder layer

The vacuum degree of the background is less than or equal to 5 x 10 ^-4 Pa, working pressure of 0.3-1.5Pa, Ar flow of 40-200sccm, and power density of 0.01-5kW/cm ² And under the condition that the substrate temperature is between Room Temperature (RT) and 300 ℃, adopting the magnetron sputtering method of the third step to continue magnetron sputtering and depositing Ag, beta-Sn, Ag-Cu, Pb-Sn, Sn-Ag alloy and other films with the thickness of 500-The film acts as an oxidation resistant protective and welding layer 8.

Further, the special magnetron sputtering technology in the third step is as follows: a permanent magnet, an electromagnetic coil or a device for mixing the electromagnetic coil and the permanent magnet are arranged on the target material to generate unbalanced magnetic field distribution 1, wherein the magnetic field intensity of an outer ring is higher than that of a core part, a closed loop is not completely formed by magnetic lines of force, and part of the magnetic lines of force of the outer ring extend to the surface of the substrate; applying a high-power pulse sputtering power supply 2 on the target material; applying a substrate negative bias 3 of 0 to-300V and an auxiliary magnetic field 4 of 0-0.7T on a sample table; the sputtering power supply 2 adopted in the magnetron sputtering process comprises one or more of a high-power pulse power supply, a modulated pulse power supply, a deep oscillation power supply and the like. By adopting the unbalanced sputtering method, part of secondary electrons can escape from the surface area of the target along magnetic lines and reach the surface of the substrate, the ion concentration of a coating area is increased, the deposition rate is increased, meanwhile, the increase of the ion beam current density of the substrate plays a certain bombardment role on the surface of a deposited film layer, the effect of cleaning an oxide layer and other impurities of a workpiece and activating the surface of the workpiece can be achieved, and meanwhile, the charged particle bombardment effect of energy carrying can achieve the modification purpose of the film layer in the coating process, so that the film layer which is more compact, stronger in binding force and more uniform is generated. The high-power supply is adopted to generate a micro-arc discharge state between the abnormal glow discharge and the arc discharge from the normal glow discharge region in a short time, and the heat effect generated by the instantaneous high-power discharge on the cathode target surface realizes the conversion of the output mechanism of the coating particles from cascade collision to thermal vibration evaporation, so that the ionization rate of the coating particles is improved, and the effect of preparing a uniform coating with uniform thickness at different spatial positions in the vacuum cavity is achieved. Due to the unsteady characteristic of gas micro-arc discharge, the high-frequency pulse electric field mainly plays a role in stably maintaining the unsteady process, the purpose of controlling the strength and the size of the arc spot is achieved by adjusting factors such as pulse amplitude, width, frequency and the like, and the generation of large liquid drops influencing the quality of a coating is prevented while the high ionization rate of coating particles is ensured. By applying a negative bias to help attract the ionized metal atoms to the substrate surface and bombard the substrate, not only a cleaning action is generated on the substrate surface impurities; meanwhile, atoms which are not firmly bonded on the surface of the substrate can be knocked off, so that film atoms which are tightly bonded and have few defects can be left, and the film forming quality is improved. The motion trajectories of electrons and ions reaching the substrate are lengthened and changed by applying the auxiliary magnetic field. The improved and optimized magnetron sputtering method can greatly improve the ionization rate and the diffraction of metal atoms and argon of the target material, generate a secondary sputtering deposition effect and enhance the coverage rate and the uniformity of the adhesion layer deposited in the hole.

Further, the dielectric filter 5 in the first step includes a ceramic filter and a plastic filter.

Compared with the prior art, the invention has the innovation points that: a method for multi-layer composite metallization of dielectric filter is provided, firstly depositing an adhesion layer with nano-scale thickness on the surface of a substrate, then depositing cheap Cu and Al as signal transmission conductor layers, and finally depositing Ag, Sn-Ag and the like as anti-oxidation protection and welding layers, wherein the Cu and Al signal transmission conductor layers are the main body parts of the multi-layer composite metal film. All the film layers are completed by adopting an improved and optimized magnetron sputtering technology, and the method comprises the following steps: the target material is arranged in a non-equilibrium magnetic field distribution mode, a high-power sputtering power supply is applied to the target material, and negative bias and an auxiliary magnetic field are applied to a sample table.

The invention has the beneficial effects that:

the adhesive layer with the nanometer thickness can greatly improve the adhesive force between the substrate and the metal film; the Cu and the Al with the micron-sized thickness are used as signal transmission conductor layers, so that the manufacturing cost of the dielectric filter is greatly reduced; the finally deposited alloy layers with the nanometer thickness of Ag, Sn-Ag and the like can provide antioxidant protection for the Cu layer and ensure the weldability of the composite metal layer. All the film layers are finished by magnetron sputtering, and the defects of environmental pollution, high cost, poor bonding force between the metal film layer and the substrate and the like of the traditional preparation technologies such as electroplating, silver spraying and the like can be overcome. The ionization rates of Ar gas and metal atoms can be greatly improved by adopting high-power pulse magnetron sputtering under the distribution of an unbalanced magnetic field, so that the substrate is immersed in plasma; furthermore, by applying a magnetic field or bias voltage on the sample stage, the diffraction of ions is improved, secondary sputtering is generated, and the like, so that the film in the hole is redistributed in growth, the problems of low coverage rate, poor uniformity and the like of the coating film in the hole in the common balanced magnetron sputtering technology can be solved, the production cost is further reduced, and the sputtering time is saved.

Drawings

FIG. 1 is a schematic structural diagram of a magnetron sputtering technique adopted in the present invention. Wherein M is ⁺ Represents a metal cation.

Fig. 2 is a schematic cross-sectional view of a multilayer composite metal film.

In the figure: 1, a non-equilibrium magnetic field; 2, sputtering power supply; 3, negatively biasing the substrate; 4, an auxiliary magnetic field; 5 a dielectric filter; 6 an adhesive layer; 7 a signal transmission conductor layer; 8 an oxidation-resistant protective layer and a welding layer.

Detailed Description

The present invention is further illustrated by the following specific examples.

Comparative example 1

The ceramic substrate is cleaned by acetone, alcohol and deionized water. Using conventional equilibrium magnetron sputtering, vacuum degree of background 5 x 10 ^-4 Pa, working pressure of 0.6Pa, Ar flow of 40sccm, and radio frequency power density of 7W/cm ² Under the conditions, a Cu signal transmission conductor layer with a thickness of 4 μm was deposited. Continuously keeping the vacuum state, adopting the traditional balanced magnetron sputtering under the working pressure of 0.5Pa and the radio frequency power density of 7W/cm ² And depositing an Ag welding layer with the thickness of 450nm at the room temperature. The ionization rate of the target material is about 7 percent by adopting the traditional balanced magnetron sputtering process, the coverage rates (the ratio of the thickness of the side wall of the hole and the thickness of the bottom film to the thickness of the plane film) of the continuously prepared multilayer metal hole side wall and the bottom film are respectively 9 percent and 16 percent, and the conductivity is 3.2 x 10 ⁷ S/m, a drawing force of 12N/mm ² (Table 1).

Example 1

And cleaning the substrate by using acetone, alcohol and deionized water. At a background vacuum degree of 5 x 10 ^-4 Pa, working pressure of 0.3Pa, Ar flow of 40sccm, and radio frequency power density of 5W/cm ² Under the condition, the substrate is bombarded by plasma for 30min to remove pollutants, generate broken bonds and dangling bonds, and improveAdhesion of the adhesion layer metal to the substrate. Then, without vacuum separation, closed field unbalanced magnetron sputtering is adopted, and the working pressure is 0.3Pa, the Ar flow is 40sccm, and the power density is 10W/cm ² And depositing a 50nm Cr adhesion layer at the substrate temperature of 300 ℃. Continuously keeping the vacuum state, adopting closed field unbalanced magnetron sputtering under the working pressure of 0.3Pa, the Ar flow of 40sccm and the power density of 10W/cm ² And depositing a Cu signal transmission conductor layer with the thickness of 4 mu m at the substrate temperature of 300 ℃. Continuously keeping the vacuum state, adopting closed field unbalanced magnetron sputtering under the working pressure of 0.3Pa and the power density of 10W/cm ² And depositing an Ag welding layer with the thickness of 500nm at the substrate temperature of 300 ℃. The ionization rate of the target material is about 16 percent by adopting a closed field unbalanced magnetron continuous sputtering process, the coverage rates of the side wall and the bottom film of the hole for preparing the multilayer metal composite film are respectively 20 percent and 36 percent, and the electric conductivity is 3.5 x 10 ⁷ S/m, a drawing force of 43N/mm ² (Table 1). Compared with the film prepared by adopting the common magnetron sputtering in the comparative example 1, the coverage rate in the hole is improved by about 2 times; the drawing force is improved by about 3 times.

Example 2

The ceramic substrate is cleaned by acetone, alcohol and deionized water. At a background vacuum degree of 5 x 10 ^-4 Pa, working pressure of 0.7Pa, Ar flow of 100sccm, and radio frequency power density of 7W/cm ² Under the condition, the substrate is bombarded by plasma for 10min to remove pollutants, generate broken bonds and dangling bonds, and improve the adhesive force between the metal and the substrate. Then, the vacuum is not removed, the closed field unbalanced high power pulse magnetron sputtering is adopted, the working air pressure is 0.5Pa, the Ar flow is 100sccm, and the power density is 1kW/cm ² And depositing a 100nm Ti adhesion layer at the substrate temperature of 100 ℃. Continuously keeping the vacuum state, adopting closed field unbalanced high power pulse magnetron sputtering under the working pressure of 0.5Pa, the Ar flow of 100sccm and the power density of 3kW/cm ² And depositing a Cu signal transmission conductor layer with the thickness of 3 mu m at the substrate temperature of 100 ℃. Continuously keeping the vacuum state, adopting closed field unbalanced high power pulse magnetron sputtering under the working pressure of 0.5Pa and the power density of 1kW/cm ² And depositing an Ag welding layer with the thickness of 800nm under the condition that the substrate temperature is 100 ℃. Unbalanced high power with closed fieldThe ionization rate of the pulse magnetron sputtering target material is about 70 percent, the coverage rates of the side wall and the bottom film of the Ti-Cu-Ag composite film hole prepared by the continuous sputtering process are respectively 28 percent and 40 percent, and the electric conductivity is 5.6 x 10 ⁷ S/m, a drawing force of 86N/mm ² (Table 1).

Example 3

The ceramic substrate is cleaned by acetone, alcohol and deionized water. At a background vacuum degree of 5 x 10 ^-4 Pa, working pressure of 1.0Pa, Ar flow of 150sccm, and radio frequency power density of 9W/cm ² Under the condition, the substrate is bombarded by plasma for 15min to remove pollutants, generate broken bonds and dangling bonds, and improve the adhesive force between the metal and the substrate. Then, without vacuum separation, closed field unbalanced high power pulse magnetron sputtering is adopted, the working pressure is 1.0Pa, the Ar flow is 150sccm, and the power density is 5kW/cm ² And depositing a 200nm Ti adhesion layer under the conditions that the substrate temperature is 200 ℃ and the substrate bias is-100V. Adopting closed field unbalanced high power pulse magnetron sputtering under the working pressure of 1.0Pa, the Ar flow of 150sccm and the power density of 5kW/cm ² And depositing a Cu signal transmission conductor layer with the thickness of 2 mu m under the conditions that the substrate temperature is 200 ℃ and the substrate bias voltage is-100V. Continuously keeping the vacuum state, adopting closed field unbalanced high power pulse magnetron sputtering under the working pressure of 1.0Pa and the power density of 5kW/cm ² And depositing a Sn-Ag welding layer with the thickness of 1 mu m under the conditions that the substrate temperature is 200 ℃ and the substrate bias is-100V. The ionization rate of the target material is about 73 percent by adopting the process, the coverage rates of the side wall and the bottom film of the prepared composite film hole are respectively 32 percent and 46.8 percent, and the conductivity is 6.2 to 10 ⁷ S/m, a drawing force of 90N/mm ² (Table 1).

Example 4

Cleaning the substrate with acetone, alcohol and deionized water, and maintaining the vacuum degree at 5 x 10 ^-4 Pa, working pressure of 2.0Pa, Ar flow of 200sccm, and radio frequency power density of 10W/cm ² Under the condition, the substrate is bombarded by plasma for 5min, pollutants are removed, broken bonds and dangling bonds are generated, and the adhesive force between the metal and the substrate is improved. Then, without breaking vacuum, applying magnetic induction intensity of 0.7T on a sample table, adopting closed field unbalanced high-power pulse magnetron sputtering with working air pressure of 2.0Pa, Ar flow of 200sccm and power density of 10kW/cm ² And depositing a TiN adhesion layer of 200nm under the conditions of substrate temperature RT and substrate bias voltage of-300V. Continuously keeping the vacuum-free state, adopting closed field unbalanced high-power pulse magnetron sputtering under the working pressure of 2.0Pa, the Ar flow of 200sccm and the power density of 10kW/cm ² And depositing an Al signal transmission conductor layer with the thickness of 3 mu m under the condition of substrate bias voltage of-300V and room temperature. Continuously keeping the vacuum-free state, adopting closed field unbalanced high-power pulse magnetron sputtering under the working pressure of 2.0Pa, the Ar flow of 200sccm and the power density of 10kW/cm ² And under the condition of substrate bias voltage of-300V and room temperature, depositing an Ag-Cu alloy film with the thickness of 500nm as a protective layer and a welding layer. The ionization rate of the target material is about 86 percent, the coverage rates of the hole side wall and the bottom film of the obtained composite film are respectively 37 percent and 51 percent, and the electric conductivity and the drawing force are respectively 5.8 x 10 ⁷ S/m and 82N/mm ² (Table 1).

TABLE 1 Properties of the multilayer composite films

As can be seen from the analysis of table 1: when a multilayer metal film is prepared by using the conventional equilibrium magnetron sputtering (comparative example 1), because the ionization rate of target atoms is low (< 10%), most of the target atoms reach the substrate and are neutral atoms, and the diffraction performance is poor, the coverage rate of the side wall and the bottom of the hole deposited by using the method is low, and is only 9% and 16%, and the electric conductivity and the drawing force are also low. The closed field unbalanced magnetron (embodiment 1) is adopted to increase the ion concentration of the coating area, the ionization rate of the target material can reach 16 percent, and thus, the sputtering source is also an ion source for bombarding the surface of the substrate and can play a role in cleaning an oxidation layer and other impurities of a workpiece; in the process of coating, the charged particle bombardment effect of the energy-carrying can achieve the purpose of modifying the film layer, so that the generated film layer has high compactness, stronger binding force and good uniformity. Meanwhile, the secondary sputtering deposition effect can be generated, so that the film growth in the holes is redistributed. Thus, example 1 resulted in a 2-fold increase in hole sidewall and bottom coverage and a 3-fold increase in pullout force, respectively, for the film compared to comparative example 1. In the embodiment 2, the high-power pulse power supply is added on the basis of the embodiment 1, and the high-power pulse power supply can generate a micro-arc discharge state between the abnormal glow discharge and the arc discharge from the normal glow discharge state in a short time, so that the ionization rate of the plating material particles is improved to 70 percent, and the effect of preparing a uniform-thickness plating layer at different spatial positions in the vacuum cavity is achieved. Therefore, example 2 further improves the step coverage, conductivity and drawing force of the thin film using a high power pulse power source, compared to example 1. Example 3 a negative bias is applied to the sample stage based on example 2, which helps to attract ionized metal atoms to the substrate surface and bombard the substrate, and at this time, atoms which are not firmly bonded to the substrate surface are knocked off, so that some thin film atoms with tight bonding and few defects are left behind, and the film forming quality is improved. In addition, the secondary sputtering deposition effect can be generated, so that the film growth in the holes is redistributed, and the step coverage rate is improved. Example 4 on the basis of example 3, an auxiliary magnetic field is applied to the sample stage, the movement tracks of electrons and ions reaching the substrate are lengthened and changed, the target ionization rate is increased to 86%, and the step coverage rate of the thin film is further increased.

Fig. 1 is a schematic structural diagram of a magnetron sputtering technique adopted by the present invention, and as shown in fig. 1, a target is set by adopting an unbalanced magnetic field, a high power pulse power supply/a deep oscillation power supply/a modulated pulse power supply are applied, and a sample stage is applied with a negative bias and an auxiliary magnetic field. As shown in FIG. 2, the magnetron sputtering technique shown in FIG. 1 is helpful to improve the ionization rate and diffraction of Ar and metal, and generate a secondary sputtering deposition effect, so that the growth of the film in the hole is redistributed, the coverage rate and uniformity of the coating film in the hole with a high aspect ratio are improved, and the ratio of the thickness of the film in the hole to the thickness of the planar film can be more than or equal to 30%.

The above-mentioned embodiments only express the embodiments of the present invention, but not should be understood as the limitation of the scope of the invention patent, it should be noted that, for those skilled in the art, many variations and modifications can be made without departing from the concept of the present invention, and these all fall into the protection scope of the present invention.

Claims

1. A dielectric filter full magnetron sputtering multilayer composite metallization method is characterized in that a base body is cleaned by a wet method, dried and placed in a vacuum cavity, and bombardment treatment is carried out on the base body by adopting plasma; secondly, depositing an adhesion layer by magnetron sputtering under the condition of not departing from vacuum; thirdly, continuously depositing a signal transmission conductor layer on the surface of the adhesion layer by adopting a magnetron sputtering method under the condition of not deviating from vacuum; finally, continuing magnetron sputtering on the surface of the signal transmission layer to grow an anti-oxidation protection layer and a welding layer; the method comprises the following specific steps:

the method comprises the following steps: cleaning the medium filter to remove organic matters, metal particles and other impurities on the surface;

step two: surface treatment of dielectric filter substrate

Placing the dielectric filter processed in the step one in a vacuum chamber, and keeping the background vacuum degree less than or equal to 5 x 10 ^-4 Pa, working pressure of 0.3-2Pa, Ar flow of 40-200sccm, and radio frequency power density of 5-10W/cm ² Under the condition, the substrate is bombarded and treated by plasma; the time for bombarding the substrate by the plasma is 5-30 min;

step three: depositing an adhesion layer

The vacuum degree of the background is less than or equal to 5 x 10 ^-4 Pa, working pressure of 0.3-0.5Pa, Ar flow of 40-200sccm, and power density of 0.01-10kW/cm ² Depositing a high-activity metal or transition metal nitride film on the surface of the dielectric filter substrate treated in the step two as an adhesion layer by adopting a special magnetron sputtering technology at the substrate temperature of between room temperature and 300 ℃;

the special magnetron sputtering technology comprises the following steps: applying an unbalanced magnetic field on the target to generate unbalanced magnetic field distribution; applying a high-power pulse sputtering power supply on the target material; applying a substrate negative bias voltage of 0 to-300V and an auxiliary magnetic field of 0-0.7T on the sample table;

the method for applying the unbalanced magnetic field on the target material comprises the following steps: a permanent magnet, an electromagnetic coil or a device for mixing the electromagnetic coil and the permanent magnet is arranged on the target material; the intensity of the outer ring magnetic field in the generated unbalanced magnetic field distribution is higher than that of the magnetic field of the core part, the magnetic lines of force do not completely form a closed loop, and part of the magnetic lines of force of the outer ring extend to the surface of the substrate;

step four: depositing a signal transmission conductor layer

The vacuum degree of the background is less than or equal to 5 x 10 ^-4 Pa, working pressure of 0.3-1.5Pa, Ar flow of 40-200sccm, and power density of 0.01-10kW/cm ² Continuously adopting the magnetron sputtering technology of the third step under the condition that the substrate temperature is between room temperature and 300 ℃, and depositing Cu and Al films on the surface of the dielectric filter base processed by the third step to be used as a signal transmission conductor layer;

step five: depositing an oxidation resistant protective and solder layer

The vacuum degree of the background is less than or equal to 5 x 10 ^-4 Pa, working air pressure of 0.3-1.5Pa, Ar flow rate of 40-200sccm, and power density of 0.01-5kW/cm ² And continuously adopting the magnetron sputtering method of the third step to continuously deposit Ag, beta-Sn, Ag-Cu, Pb-Sn and Sn-Ag films by magnetron sputtering under the condition that the substrate temperature is between room temperature and 300 ℃, and taking the films as antioxidant protection and welding layers.

2. The method of claim 1, wherein the dielectric filter of step one comprises a ceramic filter and a plastic filter.

3. The method of claim 1, wherein in the third step, the high-activity metal comprises Cr, Ta, Mo, Ti, Cu, a1 or Ni, and the transition metal nitride comprises WN, TiN or TaN.

4. The method according to claim 1, wherein in the third step, the sputtering power source comprises one or more of a high power pulse power source, a modulated pulse power source, and a deep oscillating power source.

5. The method for full magnetron sputtering multilayer composite metallization of a dielectric filter as claimed in claim 1, wherein in the third step, the thickness of the adhesion layer is 50-200 nm.

6. The method according to claim 1, wherein in the fourth step, the thickness of the signal transmission conductor layer is 2-4 μm.

7. The method as claimed in claim 1, wherein in the step five, the total thickness of the anti-oxidation protection and welding layer is 500-1000 nm.