PVD (Physical Vapor Deposition) film preparation method based on vacuum ultraviolet laser multi-frequency pulse superposition and power supply same-frequency coupling

Abstract

The invention discloses a PVD (Physical Vapor Deposition) film preparation method based on vacuum ultraviolet laser multi-frequency pulse superposition and power supply same-frequency coupling, which comprises the following steps: in an ionization region, forming a multi-frequency pulse laser beam through superposition by using one or more vacuum ultraviolet lasers with different frequencies; and a series coupling pulse bias power supply or a series coupling direct current pulse / intermediate frequency magnetic control target material power supply is adopted to regulate and control frequency and phase characteristics respectively, so that selective precise ionization is carried out on different gas-phase particles or film surface atoms growing on the film on the surface of the substrate with different ionization energies. Vacuum ultraviolet light with different frequencies is used, and a series coupling pulse bias power supply or a series coupling direct-current pulse / intermediate-frequency magnetic control target material power supply is adopted to regulate and control frequency and phase characteristics respectively, so that selective precise ionization is performed on different gas-phase particles or film surface atoms growing on a substrate surface film with different ionization energies.

Description

Technical Field

[0001] The invention relates to the technical field of thin film manufacturing, and in particular to a PVD thin film preparation method based on vacuum ultraviolet laser multi-frequency pulse superposition and power supply co-frequency coupling. Background Art

[0002] In the process of preparing thin films by vapor deposition, a high ionization rate is an important prerequisite for achieving effective control of the energy, direction, density, distribution state, etc. of the ion beam. Furthermore, achieving relatively independent control of the ionization rates of different particles is an extremely difficult but extremely important technical requirement in the process of preparing thin films by vapor deposition. All currently used technical means to improve the particle ionization rate in vapor deposition are to increase the ionization rate of all gas phase particles indiscriminately by introducing high energy. It is impossible to adjust the ionization rate ratio and optimize the control scheme for different structures (or ingredients, components, etc.), and thus it is impossible to achieve more precise targeted control, which greatly limits the development of a new generation of thin films with increasingly complex structures and components: 1) The film structure / component design in the initial stage is limited by the existing ionization rate solution, and the optimal solution has to compromise with the feasible solution; 2) The indiscriminate improvement of the ionization rate of different particles during the deposition process limits the control range of the film structure / component, hindering the further improvement and optimization of the performance / function of the film; 3) The existing technical means to improve the ionization rate also bring various problems, such as the increase in the temperature of the coating substrate (such as arc plating), large particles (such as arc plating), low deposition rate (such as high-power pulsed magnetron sputtering, i.e. HiPIMS), high cost (such as HiPIMS, laser-induced arc plating - requiring a separate pulsed laser and related supporting power supply, etc.).

[0003] For physical vapor deposition technology, it mainly includes magnetron sputtering technology, vacuum evaporation technology, vacuum arc plating technology, and high-power pulsed magnetron sputtering (HiPIMS) technology that has emerged and developed rapidly in recent years. The ionization rate of traditional magnetron sputtering technology and vacuum evaporation technology is very low, which makes the deposited film lack the continuous bombardment of high-energy ions on the film surface during the growth process, resulting in poor film density and poor bonding with the substrate material; in addition, there are also shortcomings such as the film microstructure control effect based on ion beam bombardment is not obvious. The deposited particles of vacuum arc plating technology have a high ionization rate and the prepared coating is dense. However, the generation of its arc is often accompanied by the formation of large particle droplets, which makes the prepared film have surface particle defects, affecting the film finish, adhesion, corrosion resistance, wear resistance and mechanical properties; in addition, the initial energy of the ions generated by the arc is high, which easily leads to a significant increase in the temperature of the substrate, so it is not suitable for temperature-sensitive substrates (such as materials that have undergone low-temperature heat treatment in the previous process, light alloys, organic polymer materials, etc.). High-power pulsed magnetron sputtering technology can produce highly ionized sputtered materials and generate high-density ion beams without large particle defects such as metal droplets. Assisted by appropriate substrate bias, controllable ion bombardment of the growing film can be achieved, thereby achieving effective control of the film structure, internal stress, etc., and obtaining high-quality films with significantly improved performance. However, the current biggest disadvantage of high-power pulsed magnetron sputtering technology is the slow deposition rate, mainly due to the sputtering cathode reabsorption effect, gas dilution effect, and the self-sputtering of metal ions. The sputtering yield is usually lower than the Ar ion sputtering yield. In addition, HiPIMS has poor discharge stability and process repeatability, and is currently rarely used in industrial mass production.

[0004] For chemical vapor deposition technology, the reaction equation is usually controlled or the reaction rate is increased by heating or pressurizing. By increasing the ionization rate of various gas-phase reaction particles involved in the chemical reaction, the gas reaction rate can be greatly increased, while the reaction temperature can be significantly reduced and the film formation rate can be increased, thereby achieving surface coating of temperature-sensitive substrates, which is of great significance in industrial production. At present, the main ways to increase the ionization rate of gas-phase reaction particles include adding high-frequency (radio frequency, high frequency, etc.) electric fields, dielectric layer barrier discharge enhancement, electron cyclotron resonance and other methods or technical means. However, the above means are costly and complex in structure. Moreover, the means of introducing an electric field will affect the electromagnetic field distribution in the coating chamber. The plasma distribution state and uniformity in the chamber, ion beam control, etc., all require a coordinated integrated design in the design stage of the coating equipment, which increases the design difficulty and cost, and has poor versatility and is difficult to modify later.

[0005] In view of the above-mentioned defects, the inventors of the present invention finally obtained the present invention after a long period of research and practice. Summary of the invention

[0006] The purpose of this application is to provide a PVD thin film preparation method based on the superposition of multi-frequency pulses of vacuum ultraviolet laser and the same-frequency coupling of power supply, so as to solve the technical problems raised in the above background.

[0007] To achieve the above-mentioned objectives, the present application provides the following technical solutions: a PVD thin film preparation method based on the superposition of multi-frequency pulses of vacuum ultraviolet lasers and the same-frequency coupling of power supplies. In the ionization zone, one or more vacuum ultraviolet lasers with different frequencies are used to form a multi-frequency pulse laser beam through superposition, and a series-coupled pulse bias power supply or a series-coupled DC pulse / medium-frequency magnetron target power supply is used to respectively control the frequency and phase characteristics, so as to achieve selective and precise ionization of different gas phase particles or atoms on the surface of the film growing on the substrate surface with different ionization energies.

[0008] As a preferred implementation manner in this embodiment, the gas phase particles or film surface atoms are neutral particles or low-valent ions.

[0009] As a preferred implementation manner in this embodiment, the photon energy corresponding to the characteristic light wavelength of the vacuum ultraviolet laser with a fixed light wavelength is higher than the nth ionization energy of the gas phase particles, where n is an integer not less than 1.

[0010] As a preferred implementation manner in this embodiment, the ionization zone includes a main ionization zone and a pre-ionization zone, the pre-ionization zone is connected to the main ionization zone through a particle transmission channel, a low-power vacuum ultraviolet laser light source is arranged in the pre-ionization zone, and a high-power vacuum ultraviolet laser light source is arranged in the pre-ionization zone.

[0011] As a preferred implementation manner in this embodiment, it also includes a transition zone, which is located between the pre-ionization zone and the main ionization zone and is interconnected through a particle transmission channel, and a medium-power vacuum ultraviolet laser light source is arranged in the transition zone.

[0012] As a preferred implementation in this embodiment, it also includes a transition zone, which is located between the pre-ionization zone and the main ionization zone and is connected to each other through a particle transmission channel, and a medium-power vacuum ultraviolet laser light source is arranged in the transition zone. In summary, the technical effects and advantages of the present invention are as follows: The present invention has a reasonable structure, and by using vacuum ultraviolet light of different frequencies, and adopting a series-coupled pulse bias power supply or a series-coupled DC pulse / intermediate-frequency magnetron target power supply to respectively adjust the frequency and phase characteristics, different gas-phase particles or atoms on the surface of a thin film grown on a substrate surface with different ionization energies are selectively and accurately ionized; In the present invention, multi-stage ionization is provided, so that laser energy can be more reasonably distributed and utilized, thus avoiding energy waste and reducing the influence of unnecessary thermal effects on film quality. DETAILED DESCRIPTION

[0013] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0014] Embodiment: A PVD thin film preparation method based on the superposition of multi-frequency pulses of vacuum ultraviolet laser and the same-frequency coupling of power supply is shown. In the ionization zone, by using vacuum ultraviolet light of different frequencies and adopting a series-coupled pulse bias power supply or a series-coupled DC pulse / medium-frequency magnetron target power supply to respectively control the frequency and phase characteristics, different gas phase particles or atoms on the surface of the film growing on the substrate surface with different ionization energies are selectively and accurately ionized.

[0015] Series-coupled pulse bias power supply or series-coupled DC pulse / intermediate frequency magnetron target power supply are two specific series coupling (Master-Slave synchronization, synchronous frequency and phase) modes, which can achieve the same frequency and phase (or specific phase interval) of laser ionization and bias power supply, or laser ionization and DC pulse / intermediate frequency magnetron target power supply; Method 1: A pulse bias power supply is coupled in series to efficiently accelerate the precisely selectively ionized ions. Specifically, the bias voltage accelerates the specific ions ionized by ultraviolet light to reach the surface of the sample / workpiece. The specific type of ions bombards the sample / workpiece with a specific energy under the action of the bias voltage of a set amplitude, thereby achieving precise control of the composition and structure of the film. Method 2: The series coupling of DC pulse / medium frequency magnetron target power supply can precisely control the specific gas phase particles on the target surface that have been selectively and precisely ionized (especially for alloy targets, reactive magnetron sputtering, etc., with different types of gas phase ions), control the plasma composition on the target surface and the reactions occurring therein, thereby achieving precise control of the gas phase particles / reaction products that subsequently participate in the growth of the thin film on the substrate surface.

[0016] As a preferred implementation manner in this embodiment, the gas phase particles or film surface atoms are neutral particles or low-valent ions.

[0017] The use of neutral particles or low-valent ions can reduce unnecessary chemical reactions and impurity generation during the preparation process, thereby improving the purity and quality of the film. The internal structure and chemical bonds of the film prepared using neutral particles or low-valent ions are more stable, which can effectively reduce the performance degradation that may occur during the use of the film. By selectively and accurately ionizing neutral particles or low-valent ions, the composition and structure of the film can be more accurately controlled, thereby optimizing the specific properties of the film; and under the action of multi-frequency pulsed laser beams, these particles or atoms can be more easily and accurately selected and ionized, which further enhances the ability to selectively and accurately ionize different gas phase particles or film surface atoms grown on substrate surface films with different ionization energies.

[0018] As a preferred implementation manner in this embodiment, the photon energy corresponding to the characteristic light wavelength of the vacuum ultraviolet laser with a fixed light wavelength is higher than the nth ionization energy of the gas phase particles, where n is an integer not less than 1.

[0019] By ensuring that the photon energy corresponding to the characteristic light wavelength of the vacuum ultraviolet laser is higher than the ionization energy of the gas phase particles, the ionization of the gas phase particles or the atoms on the surface of the film can be achieved more effectively, thereby improving the efficiency of the entire preparation process. The efficient ionization process helps to form a more uniform and dense film structure and reduce defects and unevenness in the film.

[0020] As a preferred implementation manner in this embodiment, the ionization zone includes a main ionization zone and a pre-ionization zone, the pre-ionization zone is connected to the main ionization zone through a particle transmission channel, a low-power vacuum ultraviolet laser light source is arranged in the pre-ionization zone, and a high-power vacuum ultraviolet laser light source is arranged in the pre-ionization zone.

[0021] The setting of the pre-ionization zone makes the ionization divided into two stages, namely the secondary ionization (one is the pre-ionization zone, the other is the main ionization zone). In the pre-ionization zone, a low-power vacuum ultraviolet laser light source (one or more vacuum ultraviolet lasers with different frequencies, which are superimposed to form a multi-frequency pulse laser beam, and the frequency and phase characteristics are respectively controlled by a series-coupled pulse bias power supply or a series-coupled DC pulse / intermediate-frequency magnetron target power supply) can initially ionize some particles to form low-valent ions or excited atoms. These initially ionized particles then enter the ionization zone and are further excited by the high-intensity vacuum ultraviolet laser. The external laser light source acts to achieve a higher degree of ionization. This staged ionization method is beneficial to improving the overall ionization efficiency, and the pre-ionization zone can preliminarily screen and ionize specific types of particles, so that the particles entering the ionization zone have a higher target, which helps to reduce the ionization of non-target particles and improve the selectivity of ionization, thereby optimizing the composition and performance of the film; at the same time, through the preliminary ionization of the pre-ionization zone, the ionization zone can work in a more stable and efficient electric field environment, which helps to reduce electric field distortion and energy loss, and improve the stability and reliability of ionization.

[0022] As a preferred implementation manner in this embodiment, it also includes a transition zone, which is located between the pre-ionization zone and the main ionization zone and is interconnected through a particle transmission channel, and a medium-power vacuum ultraviolet laser light source is arranged in the transition zone (one or more vacuum ultraviolet lasers with different frequencies, which form a multi-frequency pulse laser beam by superposition, and use a series-coupled pulse bias power supply or a series-coupled DC pulse / medium-frequency magnetron target power supply to respectively control the frequency and phase characteristics).

[0023] By setting up a transition zone to form a three-stage ionization, compared with the two-stage ionization, by adding an intermediate transition zone, the particles can be ionized more finely, so that more particles can reach the expected ionization state, thereby improving the overall ionization efficiency; the three-stage ionization design more accurately controls the ionization degree of particles with different ionization energies at different stages, thereby achieving more efficient selective ionization of specific particles or atoms; the three-stage ionization and the use of lasers of different powers and frequencies can more reasonably allocate and utilize laser energy, avoid energy waste, and reduce the impact of unnecessary thermal effects on film quality.

[0024] As a preferred implementation manner in this embodiment, the main ionization zone, the transition zone and the pre-ionization zone are all configured as conical structures, the wide ends of the main ionization zone, the transition zone and the pre-ionization zone are configured as outlets, the narrow ends of the main ionization zone, the transition zone and the pre-ionization zone are configured as inlets, the outlet of the pre-ionization zone is connected to the inlet of the transition zone through a particle transmission channel, and the outlet of the transition zone is connected to the inlet of the main ionization zone through a particle transmission channel.

[0025] The gas phase particles first enter the pre-ionization zone and then the main ionization zone, and the ionization zone or pre-ionization zone with a conical structure has a natural focusing effect; when the vacuum ultraviolet laser enters the conical area, its beam will be gradually focused to the tip of the cone, so that the laser energy is concentrated in a smaller area. This focusing effect helps to increase the probability of interaction between the laser and the gas phase particles or atoms on the surface of the film, thereby improving the ionization efficiency; at the same time, the focused laser energy is also easier to achieve precise ionization of specific particles, improving the ionization accuracy; the conical structure helps to better control the airflow in the ionization zone. In the process of PVD film preparation, the flow of gas phase particles has a great influence on the ionization process. The conical structure can guide the airflow to form a specific flow pattern in the conical area, so that the gas phase particles are more evenly exposed to the laser when passing through the ionization zone. This uniform airflow distribution helps to reduce the difference in ionization effect caused by uneven particle distribution, thereby improving the accuracy of ionization.

[0026] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A PVD thin film preparation method based on vacuum ultraviolet laser multi-frequency pulse superposition and power supply co-frequency coupling, characterized in that: In the ionization zone, one or more vacuum ultraviolet lasers with different frequencies are used to form a multi-frequency pulsed laser beam through superposition, and a series-coupled pulse bias power supply or a series-coupled DC pulse / medium-frequency magnetron target power supply is used to respectively control the frequency and phase characteristics, so as to achieve selective and precise ionization of different gas phase particles or atoms on the surface of the film growing on the substrate surface with different ionization energies.

2. The PVD thin film preparation method based on vacuum ultraviolet laser multi-frequency pulse superposition and power supply co-frequency coupling according to claim 1, characterized in that: The gas phase particles or film surface atoms are neutral particles or low-valent ions.

3. A PVD thin film preparation method based on vacuum ultraviolet laser multi-frequency pulse superposition and power supply co-frequency coupling as claimed in claim 1, characterized in that: The photon energy corresponding to the characteristic light wavelength of the vacuum ultraviolet laser with a fixed light wavelength is higher than the nth ionization energy of the gas phase particles, where n is an integer not less than 1.

4. A PVD thin film preparation method based on vacuum ultraviolet laser multi-frequency pulse superposition and power supply co-frequency coupling as claimed in claim 1, characterized in that: The ionization zone includes a main ionization zone and a pre-ionization zone. The pre-ionization zone is connected to the main ionization zone through a particle transmission channel. A low-power vacuum ultraviolet laser light source is arranged in the pre-ionization zone, and a high-power vacuum ultraviolet laser light source is arranged in the main ionization zone.

5. A PVD thin film preparation method based on vacuum ultraviolet laser multi-frequency pulse superposition and power supply co-frequency coupling as claimed in claim 4, characterized in that: It also includes a transition zone, which is located between the pre-ionization zone and the main ionization zone and is connected to each other through a particle transmission channel. A medium-power vacuum ultraviolet laser light source is arranged in the transition zone.

6. A PVD thin film preparation method based on vacuum ultraviolet laser multi-frequency pulse superposition and power supply co-frequency coupling as claimed in claim 5, characterized in that: The main ionization zone, the transition zone and the pre-ionization zone are all configured as conical structures, the wide ends of the main ionization zone, the transition zone and the pre-ionization zone are configured as outlets, the narrow ends of the main ionization zone, the transition zone and the pre-ionization zone are configured as inlets, the outlet of the pre-ionization zone is connected to the inlet of the transition zone through a particle transmission channel, and the outlet of the transition zone is connected to the inlet of the main ionization zone through a particle transmission channel.