Method for polishing and planarizing thin film material

Abstract

The invention relates to the technical field of advanced laser processing, in particular to a method for polishing and planarizing a thin film material. The method comprises the following steps: carrying out ultrafast laser processing on a thin film material; the parameters of the ultrafast laser processing are as follows: the wavelength of ultrafast laser is 100-2000 nm, and the pulse width of the ultrafast laser is 1 fs-1 ns; the thickness of the thin film material is 1 nm to 1000 [mu] m. The ultrafast laser processing method adopted by the invention is a non-contact surface treatment means, and the damage of the polishing procedure to the film body can be obviously reduced; the surface of the thin film material is treated by adopting the ultrafast laser with narrow pulse width, the treatment of the thin film material is realized by utilizing the photophysical, photochemical and photomechanical actions generated when the ultrafast laser irradiates the surface of the thin film material, and the surface roughness of the thin film material is obviously reduced.

Description

Technical Field

[0001] The invention relates to the technical field of advanced laser processing, and in particular to a method for polishing and flattening a thin film material. Background Art

[0002] In thin film materials, burrs, particles and other undulating features formed by the enrichment of deposited atoms are common surface defects, which will significantly increase the surface roughness of the film and have an adverse effect on the performance and reliability of the film, resulting in a decrease in the mechanical, optical, electrical, magnetic, thermal and tribological properties of the film, as well as a shortened film service life. For example, in the conductive slip ring of the artificial satellite solar wing, the burr structure on the surface of the sliding electrical contact film material will simultaneously aggravate the mechanical wear and electrical wear of the brush-conductive ring friction pair; on the one hand, the presence of the burr structure will increase the adhesive wear of the sliding contact surface, and as the sliding friction proceeds, part of the burr structure will break and roll between the contact surfaces in the form of abrasive particles, resulting in abrasive wear of the film; on the other hand, under the condition of sliding electrical contact friction, the burr structure on the film surface will increase the contact resistance sharply, and the material at the contact point is prone to melting and splashing under the action of Joule heat, that is, the electrical wear caused by arc erosion will also increase synchronously. In order to reduce the impact of surface burrs, particles and other undulating features on the physical and chemical properties and service life of the film, it is necessary to adopt corresponding precision processing technology to polish and flatten the surface of the film, effectively remove or control surface burrs, particles and other undulating features, reduce the surface roughness of the film, and at the same time not cause additional damage to the film itself.

[0003] In traditional industrial production, contact methods such as mechanical polishing, chemical polishing and magnetic fluid polishing are usually used to polish and flatten the surface of materials. In addition, hot melt polishing technology based on continuous laser or long pulse laser has also achieved rapid development in recent years. By optimizing the polishing process and controlling the polishing parameters, the above polishing technology can meet the requirements of most industrial processing and greatly improve the surface smoothness of the material. However, for the polishing and flattening of the surface of thin film materials, the above polishing technology faces great challenges. The thickness of thin film materials commonly used in different application fields is generally in the micrometer or even nanometer scale, and the hardness of thin film materials that have not been doped and strengthened by alloy elements is relatively low. If contact or hot melt polishing methods are used, it is easy to cause warping, cracking, and shedding of the film, which will inevitably cause a certain degree of mechanical damage or thermal damage to the surface of the film, and it is easy to introduce new pollution during the polishing process, which cannot meet the requirements of ultra-precision polishing and flattening. For thin film materials with smaller thickness, the above challenges will become more prominent; for thin film materials whose surface burrs, particles and other fluctuation features are already in the submicron or even nanometer scale, it will also face greater challenges to further reduce their surface roughness. Considering the growing demand for thin film materials and the high quality requirements for the surface of thin film materials in key areas such as optoelectronic devices, energy devices, and high-end equipment, it is urgently necessary to develop a non-contact and non-hot-melt surface polishing and flattening method for thin film materials, which has both high efficiency and ultra-precision processing capabilities. It can effectively remove burrs, particles and other undulating features on the surface of the film without causing additional damage to the film itself, thereby reducing the surface roughness of the film and improving its physical and chemical properties and application performance. Summary of the invention

[0004] The present invention aims to solve one of the technical problems in the related art at least to a certain extent. To this end, the present invention provides a method for polishing and planarizing a thin film material, which can significantly reduce the surface roughness of the thin film.

[0005] To this end, the first aspect of the present invention provides a method for polishing and planarizing a thin film material, comprising the following steps:

[0006] Ultrafast laser processing of thin film materials;

[0007] The parameters of the ultrafast laser processing are: the wavelength of the ultrafast laser is 100 to 2000 nm, and the pulse width of the ultrafast laser is 1 fs to 1 ns;

[0008] The thickness of the thin film material is 1 nm to 1000 μm.

[0009] The ultrafast laser processing method adopted in the present invention is a non-contact surface treatment method, which can significantly reduce the damage to the film body caused by the polishing process; the present invention uses an ultrafast laser with a narrow pulse width to treat the surface of the film material, and utilizes the photophysical, photochemical and photomechanical effects generated when the ultrafast laser is irradiated on the surface of the film material to achieve the treatment of the film surface material, significantly reduce the surface roughness of the film material, and will not produce incidental thermal effects and thermal stresses on the material in the irradiated area. It is a cold polishing method that will not cause thermal damage or form thermal cracks on the surface of the polished object.

[0010] In some embodiments of the present invention, the roughness of the thin film material is 1 nm to 100 μm.

[0011] In some embodiments of the present invention, the pulse frequency of the ultrafast laser is 1 kHz to 1 GHz. The pulse frequency of the present invention is relatively high, and more pulse energy can be transmitted per unit time, thereby increasing the material removal rate and accelerating the processing speed.

[0012] In some embodiments of the present invention, the power of the ultrafast laser is 1 mW to 1 kW. The ultrafast laser of the present invention has a relatively high power, which can further produce photophysical, photochemical and photomechanical effects on the surface of the thin film material to reduce the surface roughness of the thin film material.

[0013] In some embodiments of the present invention, the defocusing amount of the ultrafast laser is 0 to 10000 μm. The present invention finely controls the defocusing amount of the ultrafast laser to obtain the expected surface polishing and flattening effect of the thin film material.

[0014] In some embodiments of the present invention, the spacing of the scanning filling lines of the ultrafast laser is 1 to 100 μm. The present invention finely controls the spacing of the scanning filling lines of the ultrafast laser to obtain the expected surface polishing and flattening effect of the thin film material.

[0015] In some embodiments of the present invention, the scanning speed of the ultrafast laser is 1 to 10000 mm / s. The present invention finely controls the scanning speed of the ultrafast laser to obtain the expected surface polishing and flattening effect of the thin film material.

[0016] In some embodiments of the present invention, the number of ultrafast laser scans is 1 to 1000. The present invention finely controls the number of ultrafast laser scans to obtain the expected surface polishing and flattening effects of thin film materials.

[0017] In some embodiments of the present invention, the thin film material includes a metal thin film and / or an inorganic non-metallic thin film.

[0018] In some embodiments of the present invention, the ultrafast laser processing is performed in the presence of air or a protective gas.

[0019] In some embodiments of the present invention, the protective gas includes one or more of argon, helium, or nitrogen.

[0020] Additional aspects and advantages of the present invention will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present invention. Brief Description of the Drawings

[0021] The above and / or additional aspects and advantages of the present invention will become apparent and be readily understood from the description of the embodiments in conjunction with the following drawings, wherein:

[0022] Figure 1 A schematic diagram of a laser processing system according to an embodiment of the present invention is shown;

[0023] Figure 2 Scanning electron microscope images showing the surface morphology of a magnetron sputtered Au film before and after polishing and planarization treatment in Example 1 of the present invention, (a) is the magnetron sputtered Au film before polishing and planarization treatment, and (b) is the magnetron sputtered Au film after polishing and planarization treatment;

[0024] Figure 3 Atomic force microscope images showing the surface morphology of a magnetron sputtered Au film before and after polishing and planarization treatment in Example 1 of the present invention, (a) is the magnetron sputtered Au film before polishing and planarization treatment, and (b) is the magnetron sputtered Au film after polishing and planarization treatment;

[0025] Figure 4 Curves of nanoindentation tests of a magnetron sputtered Au film before and after polishing and planarization treatment in Example 1 of the present invention are shown;

[0026] Figure 5 Curves of friction coefficient fitting of a magnetron sputtered Au film before and after polishing and planarization treatment in Example 1 of the present invention are shown;

[0027] Figure 6 Scanning electron microscope images showing the surface morphology of a magnetron sputtered Au film polished by a nanosecond laser in Comparative Example 1 of the present invention are shown;

[0028] Figure 7 Scanning electron microscope images and atomic force microscope images showing the surface morphology of a magnetron sputtered Au film polished by a nanosecond laser in Comparative Example 2 of the present invention are shown.

[0029] Description of the reference numerals:

[0030] Ultra-fast laser 1, mirror 2, beam expander 3, aperture 4, mirror 5, scanning galvanometer 6, field lens 7, processing platform 8, control computer 9. Detailed Description of the Embodiments

[0031] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be understood as limiting the present invention.

[0032] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. Further, in the description of the present invention, unless otherwise specified, the meaning of "plurality" is two or more.

[0033] A first aspect of the present invention provides a method for polishing and planarizing a thin film material, comprising the following steps:

[0034] Ultrafast laser processing of thin film materials;

[0035] The parameters of the ultrafast laser processing are: the wavelength of the ultrafast laser is 100 to 2000 nm, and the pulse width of the ultrafast laser is 1 fs to 1 ns;

[0036] The thickness of the thin film material is 1 nm to 1000 μm.

[0037] The ultrafast laser processing method adopted in the present invention is a non-contact surface treatment method, which can significantly reduce the damage to the film body caused by the polishing process; the present invention uses an ultrafast laser with a narrow pulse width to treat the surface of the film material, and utilizes the photophysical, photochemical and photomechanical effects generated when it is irradiated on the material surface to achieve the treatment of the film surface material, significantly reduce the surface roughness of the film material, and will not produce incidental thermal effects and thermal stresses on the material in the irradiated area. It is a cold polishing method that will not cause thermal damage or form thermal cracks on the surface of the polished object.

[0038] In some embodiments of the present invention, the wavelength of the ultrafast laser includes ultraviolet light, visible light and infrared light.

[0039] In some embodiments of the present invention, as an example, the wavelength of the ultrafast laser can be 193nm, 206nm, 213nm, 248nm, 258nm, 266nm, 308nm, 337nm, 343nm, 345nm, 355nm, 390nm, 400nm, 445nm, 488nm, 514nm, 515nm, 517nm, 532nm, 633nm, 655nm, 658nm, 780nm, 800nm, 810nm, 900nm, 920nm, 940nm, 980nm, 1030nm, 1035nm, 1064nm, 1315nm, 1470nm, 1500nm, 1550nm, 2000nm, etc.

[0040] In some embodiments of the present invention, as an example, the pulse width of the ultrafast laser can be 1 fs, 10 fs, 20 fs, 30 fs, 40 fs, 50 fs, 60 fs, 70 fs, 80 fs, 90 fs, 100 fs, 150 fs, 200 fs, 250 fs, 300 fs, 350 fs, 400 fs, 450 fs, 500 fs, 550 fs, 600 fs, 650 fs, 700 fs, 750 fs, 800 fs, 850 fs, 90 0fs, 950fs, 1ps, 2ps, 3ps, 4ps, 5ps, 6ps, 7ps, 8ps, 9ps, 10ps, 11ps, 12ps, 13ps, 14ps, 15ps, 16ps, 17ps, 18p s, 19ps, 20ps, 25ps, 30ps, 50ps, 100ps, 200ps, 300ps, 400ps, 500ps, 600ps, 700ps, 800ps, 900ps, 1000ps.

[0041] In some embodiments of the present invention, the pulse frequency of the ultrafast laser is 1 kHz to 1 GHz. As an example, the pulse frequency of the ultrafast laser can be 1 kHz, 10 kHz, 20 kHz, 30 kHz, 40 kHz, 50 kHz, 60 kHz, 70 kHz, 80 kHz, 90 kHz, 100 kHz, 110 kHz, 120 kHz, 130 kHz, 140 kHz, 150 kHz, 160 kHz, 170 kHz, 180 kHz, 190 kHz, 200 kHz, 300 kHz, 400 kHz, 500 kHz, 600 kHz, 700 kHz, 800 kHz, 900 kHz, 10 ...0 kHz, 1200 kHz, 1300 kHz, 1400 kHz, 1500 kHz, 1600 kHz, 1700 kHz, 1800 kHz, 1900 kHz, 2000 kHz, 3000 kHz, 4000 kHz, 5000 kHz, 6000 kHz, 7000 kHz, 8000 kHz, 9000 kHz, 1000 kHz, 1100 kHz, 800kHz, 900kHz, 1MHz, 2MHz, 3MHz, 4MHz, 5MHz, 6MHz, 7MHz, 8MHz, 9MHz, 10MHz, 20MHz, 30MHz, 40MHz, 50MHz, 60MHz, 70MHz, 80MHz, 90MHz, 100MHz, 200MHz, 300MHz, 400MHz, 500MHz, 600MHz, 700MHz, 800MHz, 900MHz, 1GHz. The pulse frequency of the present invention is higher, and more pulse energy can be transmitted per unit time, thereby improving the material removal rate and accelerating the processing speed.

[0042] In some embodiments of the present invention, the power of the ultrafast laser is 1 mW to 1 kW. As an example, the power of the ultrafast laser can be 1 mW, 10 mW, 20 mW, 30 mW, 40 mW, 50 mW, 60 mW, 70 mW, 80 mW, 90 mW, 100 mW, 110 mW, 120 mW, 130 mW, 140 mW, 150 mW, 160 mW, 170 mW, 180 mW, 190 mW, 200 mW, 300 mW, 400 mW, 500 mW, 600 mW, 700 mW, 800 mW, 900 mW, 10 ...0 mW, 1200 mW, 1300 mW, 1400 mW, 1500 mW, 1600 mW, 1700 mW, 1800 mW, 1900 mW, 2 0mW, 400mW, 500mW, 600mW, 700mW, 800mW, 900mW, 1W, 2W, 3W, 4W, 5W, 6W, 7W, 8W, 9W, 10W, 20W, 30W, 40W, 50W, 60W, 70W, 80W, 90W, 100W, 200W, 300W, 400W, 500W, 1kW. The ultrafast laser of the present invention has a high power, which can further produce photophysical, photochemical and photomechanical effects on the surface of the thin film material to reduce the surface roughness of the thin film material.

[0043] In some embodiments of the present invention, the spot energy distribution of the ultrafast laser can be Gaussian distribution, flat-top distribution, linear distribution, annular distribution, or other desired distribution forms.

[0044] In some embodiments of the present invention, the defocus of the ultrafast laser is 0 to 10000 μm. As an example, the defocus of the ultrafast laser can be 0, 1, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000, 10000 μm. The present invention finely controls the defocus of the ultrafast laser to obtain the expected surface polishing and flattening effect of the thin film material.

[0045] In some embodiments of the present invention, the laser processing trajectory includes a processing trajectory of a two-dimensional plane and a processing trajectory of a three-dimensional surface; further, the laser scanning path includes regularly arranged filling lines, such as a unidirectional parallel arrangement, a bidirectional cross arrangement, a star-shaped arrangement with any cross angle, etc., and also includes filling lines along the contour of the target area to be flattened, such as concentric circle filling, spiral line filling, and zigzag line filling.

[0046] In some embodiments of the present invention, the spacing of the scanning filling lines of the ultrafast laser is 1 to 100 μm. As an example, the spacing of the scanning filling lines of the ultrafast laser can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 μm. The present invention finely controls the spacing of the scanning filling lines of the ultrafast laser to obtain the expected surface polishing and flattening effect of the thin film material.

[0047] In some embodiments of the present invention, the scanning speed of the ultrafast laser is 1 to 10000 mm / s. As an example, the scanning speed of the ultrafast laser is 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000, 10000 mm / s. The present invention finely controls the scanning speed of the ultrafast laser to obtain the expected surface polishing and flattening effect of the thin film material.

[0048] In some embodiments of the present invention, the number of scans of the ultrafast laser is 1 to 1000 times. As an example, the number of scans of the ultrafast laser is 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 300, 400, 500, 600, 700, 800, 900, 1000 times. The present invention finely controls the number of scans of the ultrafast laser to obtain the expected surface polishing and flattening effect of the thin film material.

[0049] In some embodiments of the present invention, the ultrafast laser processing is performed in the presence of air or a protective gas; further, the protective gas is a high-purity protective gas; further, the protective gas includes argon (Ar), helium (He) or nitrogen (N 2 )

[0050] In some embodiments of the present invention, the volume flow rate of the protective gas is 0 to 100 L / min. As an example, the volume flow rate of the protective gas can be 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 L / min.

[0051] In some embodiments of the present invention, dust removal during laser processing can be performed by overall dust removal (i.e. placing the entire processing system in a dust removal space) or in-situ dust removal (i.e. performing in-situ dust removal on the laser processing area).

[0052] In some embodiments of the present invention, the thin film material includes a metal thin film and / or an inorganic non-metallic thin film.

[0053] In some embodiments of the present invention, the metal film includes one or more of a single metal film and an alloy film.

[0054] In some embodiments of the present invention, the single metal film includes one or more of platinum (Pt) film, gold (Au) film, silver (Ag) film, copper (Cu) film, titanium (Ti) film, chromium (Cr) film, nickel (Ni) film, molybdenum (Mo) film, tungsten (W) film, zinc (Zn) film, tin (Sn) film, vanadium (V) film, zirconium (Zr) film, tantalum (Ta) film, hafnium (Hf) film, and aluminum (Al) film.

[0055] In some embodiments of the present invention, the alloy film includes one or more of an iron-carbon alloy film, an aluminum alloy film, a zinc alloy film, a copper alloy film, a titanium alloy film, a magnesium alloy film, a nickel alloy film, a manganese alloy film, a tungsten alloy film, a nickel-titanium alloy film, a nickel-chromium alloy film, a zinc-aluminum alloy film, a titanium-aluminum alloy film, a copper-nickel alloy film, a copper-aluminum-nickel alloy film, and a nickel-iron alloy film.

[0056] In some embodiments of the present invention, the inorganic non-metallic film includes an oxide film, a nitride film, a carbide film, lithium niobate (LiNbO 3 ) thin film, lithium tantalate (LiTaO 3 ) film or films.

[0057] In some embodiments of the present invention, the oxide film comprises silicon dioxide (SiO 2 ) film, aluminum oxide (Al 2 O 3 ) thin film, titanium oxide (TiO 2 ) thin film, tin oxide (SnO 2 ) thin film, zinc oxide (ZnO) thin film, vanadium oxide (VO 2 、V 2 O 5 ) thin film, zirconium oxide (ZrO 2 ) thin film, tantalum oxide (Ta 2 O 5 ) thin film, hafnium oxide (HfO 2 ) film, fluorine-doped tin dioxide (FTO) film, indium tin oxide (ITO) film, tungsten-doped indium oxide (IWO) film, aluminum-doped zinc oxide (AZO) film, boron-doped zinc oxide (BZO) film or indium zinc oxide (IZO) film.

[0058] In some embodiments of the present invention, the nitride film includes titanium nitride (TiN) film, zirconium nitride (ZrN) film, hafnium nitride (HfN) film, chromium nitride (CrN) film, vanadium nitride (VN) film, niobium nitride (NbN) film, tantalum nitride (TaN) film, 2 N) film, aluminum nitride (AlN) film, silicon nitride (Si 3 N 4 ) film, boron nitride (BN) film or one or more thereof.

[0059] In some embodiments of the present invention, the carbide film includes titanium carbide (TiC) film, tungsten carbide (WC) film, tantalum carbide (TaC) film, chromium carbide (Cr 3 C 2) film, silicon carbide (SiC) film, vanadium carbide (VC) film, zirconium carbide (ZrC) film, boron carbide (B 4 C) one or more of the thin films.

[0060] In some embodiments of the present invention, as an example, the thickness of the thin film material can be 1nm, 2nm, 3nm, 4nm, 5nm, 6nm, 7nm, 8nm, 9nm, 10nm, 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, 110nm, 120nm, 130nm, 140nm, 150nm, 160nm, 170nm, 180nm, 190nm, 200nm, 300nm, 400nm, 500nm, 600nm, 700nm, 800nm, 900nm, 1μm, 10μm, 20μm, 30μm, 40μm, 50μm , 60μm, 70μm, 80μm, 90μm, 100μm, 200μm, 300μm, 400μm, 500μm, 600μm, 700μm, 800μm, 900μm, 1000μm.

[0061] In some embodiments of the present invention, the roughness of the thin film material is 1 nm to 100 μm. As an example, the roughness of the thin film material can be 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 μm.

[0062] The present invention has no special requirements for the preparation process of the thin film material. In some embodiments of the present invention, the preparation process of the thin film material includes physical vapor deposition (magnetron sputtering, vacuum evaporation, electron beam coating, ion beam coating, pulsed laser deposition, etc.) or chemical vapor deposition (atmospheric pressure chemical vapor deposition (APCVD), low pressure chemical vapor deposition (LPCVD), ultrahigh vacuum chemical vapor deposition (UHVCVD), laser assisted chemical vapor deposition (LCVD), plasma enhanced chemical vapor deposition (PECVD)).

[0063] In some embodiments of the present invention, during testing, the thin film material is disposed on a surface of a substrate; further, the substrate comprises one or more of silicon, silicon oxide, silicon nitride, sapphire, glass or alloy materials.

[0064] In some embodiments of the present invention, the thickness of the substrate is 100 to 1000 μm.

[0065] In some embodiments of the present invention, a Cr layer is disposed between the thin film material and the substrate. The Cr layer can enhance the bonding strength between the thin film material and the substrate.

[0066] In some embodiments of the present invention, the thickness of the Cr layer is 1 to 50 nm.

[0067] In some embodiments of the present invention, the thin film material is pretreated before being subjected to the ultrafast laser processing; further, the pretreatment includes cleaning and drying.

[0068] In some embodiments of the present invention, the solvent used for cleaning includes water and / or an organic solvent; further, the organic solvent includes an alcohol solvent.

[0069] In some embodiments of the present invention, the cleaning includes ultrasonic cleaning; further, the ultrasonic cleaning time is 1 to 240 minutes; further, the ultrasonic cleaning time of the thin film material in water is 1 to 120 minutes, and the ultrasonic cleaning time of the thin film material in an organic solvent is 1 to 120 minutes.

[0070] In some embodiments of the present invention, the drying may be performed by heating or gas drying.

[0071] In some embodiments of the present invention, the heating and drying is carried out at a temperature of 20 to 200° C. and a time of 1 to 120 min.

[0072] In some embodiments of the present invention, the gas used for the gas drying includes nitrogen and / or argon; further, the gas pressure is 1 to 200 bar, and the gas drying time is 1 to 300 s.

[0073] In some embodiments of the present invention, after the thin film material is subjected to the ultrafast laser processing, the thin film material is pretreated; further, the pretreatment includes cleaning and drying.

[0074] In some embodiments of the present invention, the solvent used for cleaning includes water and / or an organic solvent; further, the organic solvent includes an alcohol solvent.

[0075] In some embodiments of the present invention, the cleaning includes ultrasonic cleaning; further, the ultrasonic cleaning time is 1 to 240 minutes; further, the ultrasonic cleaning time of the thin film material in water is 1 to 120 minutes, and the ultrasonic cleaning time of the thin film material in an organic solvent is 1 to 120 minutes.

[0076] In some embodiments of the present invention, the drying may be performed by heating or gas drying.

[0077] In some embodiments of the present invention, the heating and drying is carried out at a temperature of 20 to 200° C. and a time of 1 to 120 min.

[0078] In some embodiments of the present invention, the gas used for the gas drying includes nitrogen and / or argon; further, the gas pressure is 1 to 200 bar, and the gas drying time is 1 to 300 s.

[0079] In some embodiments of the present invention, a method for polishing and planarizing a thin film material is implemented based on the following devices and instruments: including an ultrafast laser polishing and planarizing system, an ultrasonic cleaning device, a surface morphology acquisition instrument, a surface roughness measuring instrument, and a thin film mechanical properties testing instrument. The method of the present invention specifically includes the following steps:

[0080] Step 1: Build an ultrafast laser polishing and flattening system, including configuring an ultrafast laser with specific wavelength, pulse width, repetition rate, power, and spot energy distribution characteristics, an external optical path system, a motion system, an observation system, a gas protection system, a dust removal system, etc.; the laser output by the ultrafast laser passes through a reflector, a beam expander, an aperture, a reflector, a scanning galvanometer, and an F-Theta field mirror in turn and then acts on the processing platform.

[0081] Step 2: Ultrasonic cleaning of the film sample to be flattened is performed with anhydrous ethanol and deionized water to remove pollutants attached to the surface of the film, and the cleaned sample is placed on a constant temperature heating table for drying, or blown dry with an inert gas such as nitrogen or argon.

[0082] Step 3: Use scanning electron microscope, atomic force microscope, laser confocal microscope, 3D topography instrument, etc. to shoot the original microscopic morphology of the film material surface, record the height, spacing, number and other geometric and distribution information of the burrs, particles and other undulating features on the film surface, and measure the roughness of the original surface of the film. The geometric and distribution information of the burrs, particles and other undulating features on the original surface of the film measured by scanning electron microscope, atomic force microscope, laser confocal microscope, 3D topography instrument, etc. will serve as an important basis for setting the scanning path, scanning spacing, scanning speed, number of scans, laser power, pulse width, repetition frequency, defocus height and other processing trajectories and processing parameters in steps 4 and 5.

[0083] Step 4: Place the thin film sample to be flattened after ultrasonic cleaning on the processing platform described in step 1, and set the area range, processing trajectory, scanning path, scanning spacing, scanning speed, number of scans, etc. of the laser flattening processing in the scanning galvanometer and processing platform control software.

[0084] Step 5: Set the laser power, pulse width, repetition frequency, etc. in the laser control software. Adjust the Z-axis height of the processing platform through the processing platform control software or adjust the focal position of the laser through the three-dimensional scanning galvanometer control software so that the surface of the sample to be flattened has a suitable defocus amount relative to the laser focus spot. The ultrafast laser polishing and flattening method adopted by the present invention is a non-contact surface treatment method. The polishing and flattening process does not require the introduction of mechanical external force or electromagnetic external field. Compared with contact polishing methods such as mechanical polishing, chemical polishing, chemical mechanical polishing, and magnetic fluid polishing, it can significantly reduce the damage to the film body caused by the polishing process, and there is no need to use chemical reagents such as polishing liquid and polishing paste. The processed product has no pollution to the environment and is a green surface processing method.

[0085] Step six: Move the processing platform horizontally through the processing platform control software, locate the starting point of the laser flattening process with the help of the in-situ observation system (CCD camera or microscope) or the guiding red light emitted from the scanning galvanometer, turn on the protective gas device and the dust removal device, turn on the laser in the laser and scanning galvanometer control software, and scan it according to the pre-set processing trajectory, scanning path and processing parameters, and start flattening the film surface. The processing platform can move in three directions: X, Y, and Z. The X and Y directions are horizontal directions, and the Z direction is the height direction. According to the shape requirements of the sample to be flattened, the rotation axis and the tilt axis can also be configured in the processing platform to achieve more degrees of freedom of relative movement and flexible control of the relative position of the laser-sample surface. And according to the shape, size, target area, etc. of the sample to be flattened, the area range of the laser flattening process can be set in the software, which can be 1μm. 2 ~1m 2 . The scanning galvanometer can be a two-dimensional scanning galvanometer, a three-dimensional scanning galvanometer, a dynamic focusing galvanometer, etc. The laser processing trajectory includes the processing trajectory of a two-dimensional plane and the processing trajectory of a three-dimensional curved surface, wherein the three-dimensional processing trajectory can be achieved by a three-dimensional scanning galvanometer, a dynamic focusing galvanometer, or a multi-axis processing platform. The present invention uses a scanning galvanometer and a multi-axis processing platform to control the relative motion trajectory and laser processing path of the ultrafast laser and the film surface. The laser processing trajectory, scanning path and process parameters can be conveniently customized and finely controlled in the control software according to the shape, size, target area, original surface roughness, etc. of the film sample to be flattened, so as to obtain the expected surface polishing and flattening effect.

[0086] Step 7: After completing the specified processing trajectory, scanning path and processing times, the laser stops emitting light, the protective gas device and the dust removal device are turned off, and the flattening process is completed; the thin film samples after flattening are ultrasonically cleaned with anhydrous ethanol, deionized water, etc., and the cleaned samples are placed on a constant temperature heating table for drying, or blown dry with inert gases such as nitrogen and argon.

[0087] Step 8: Use a scanning electron microscope, an atomic force microscope, a laser confocal microscope, a three-dimensional topography instrument, etc. to photograph the microscopic morphology of the surface of the thin film material after flattening treatment, observe the geometry and distribution of undulating features such as burrs and particles, measure the roughness of the film surface after flattening treatment, and compare it with the expected value; if the measured surface roughness is less than the expected value, the laser flattening process is completed; if the measured surface roughness is greater than the expected value, repeat steps 4 to 7 until the surface roughness of the thin film material is reduced to the expected value.

[0088] Step nine: Use nano scratch tester, nano indenter, atomic force microscope, four-probe tester and other instruments to measure the mechanical, electrical and tribological properties of the original surface of the thin film material and the surface of the thin film material after laser flattening treatment, and analyze the improvement effect of laser flattening treatment on the performance of the thin film material. Use nano scratch tester, nano indenter, atomic force microscope, four-probe tester and other instruments to measure the mechanical, electrical and tribological properties of the original surface of the thin film material and the surface of the thin film material after laser flattening treatment, and analyze the improvement effect of laser flattening treatment on the performance of the thin film material. The area size of the film material surface after flattening treatment is photographed and measured using a scanning electron microscope, atomic force microscope, laser confocal microscope, three-dimensional topography instrument, etc. is 0.01μm. 2 ~1mm 2 ; Depending on the type of film material and the original surface condition, the expected value of the surface roughness Ra of the film after polishing and flattening is in the range of 0.1nm to 10μm. While reducing the surface roughness of the film material, the present invention can also generate an extremely thin hardened layer on the surface of the film, thereby improving the surface hardness and wear resistance of the film.

[0089] The scheme of the present disclosure will be explained below in conjunction with the examples. Those skilled in the art will appreciate that the following examples are only used to illustrate the present disclosure and should not be considered to limit the scope of the present disclosure. Where specific techniques or conditions are not indicated in the examples, the techniques or conditions described in the literature in this area or the product instructions are used. Where the manufacturers of reagents or instruments are not indicated, they are all conventional products that can be obtained commercially.

[0090] Example 1

[0091] The method for polishing and planarizing the thin film material of this embodiment comprises the following steps:

[0092] (1) Build and configure an ultrafast laser polishing and planarization system

[0093] The ultrafast laser polishing and planarization system of this embodiment is as follows Figure 1 As shown, the laser output by the ultrafast laser 1 passes through the reflector 2, the beam expander 3, the aperture 4, the reflector 5, the scanning galvanometer 6 and the field lens 7 (F-Theta field lens) in sequence and then acts on the processing platform 8. The ultrafast laser 1, the scanning galvanometer 6 and the processing platform 8 are connected to the control computer 9 through wires; the ultrafast laser is an ultraviolet femtosecond laser, and the wavelength of the ultrafast laser is 343nm.

[0094] (2) Pretreatment of samples

[0095] A sample with a size of 10 mm × 10 mm was ultrasonically cleaned with anhydrous ethanol for 25 minutes, and then ultrasonically cleaned with deionized water for 25 minutes; the cleaned sample was placed on a constant temperature heating table for drying; the temperature of the constant temperature heating table was set to 60°C, and the drying time was 2 minutes; the sample consisted of a substrate, a Cr bonding layer and a magnetron sputtered Au film stacked in sequence, the substrate was single crystal Si, the thickness of the substrate was 450 μm, the thickness of the Cr bonding layer was 10 nm, and the thickness of the magnetron sputtered Au film was 200 nm.

[0096] (3) Observation of the original microscopic morphology of the magnetron sputtered Au film surface

[0097] Scanning electron microscope and atomic force microscope were used to photograph the original microscopic morphology of the magnetron sputtered Au film surface of the sample, record the height, spacing, number and other geometric and distribution information of the surface burrs, particles and other undulating features, and measure the roughness of the original surface of the film. The test results are as follows: Figure 2 (a) and Figure 3 As shown in (a), Figure 2 (a) It can be seen that after the ultrasonic cleaning in step (2), the original surface of the magnetron sputtered Au film of the sample still has densely distributed burrs, particles and other undulating features, which significantly reduces the surface quality of the magnetron sputtered Au film of the sample; Figure 3 (a) It can be seen that the original surface roughness Ra of the magnetron sputtered Au film of the sample is 6.15 nm; the shooting area size of the atomic force microscope is 50 μm×50 μm.

[0098] (4) Set relevant parameters

[0099] The sample obtained in step (3) is placed on a processing platform, and the area range, processing trajectory, scanning path, scanning spacing, scanning speed, number of scans, etc. of the laser planarization processing are set in the scanning galvanometer and processing platform control software of the computer; the area range of the laser planarization processing is 9.8 mm × 9.8 mm, and a non-processing area with a width of 0.1 mm is reserved along the edge of the magnetron sputtered Au film of the sample. The scanning path adopts a bidirectional cross arrangement, the scanning spacing is 5 μm, the scanning speed is 1000 mm / s, and the number of scans is 2 times.

[0100] (5) Set relevant parameters

[0101] The power, pulse width, repetition frequency, etc. of the ultraviolet femtosecond laser were set in the laser control software of the computer; the laser power was 10 W, the pulse width was 500 fs, and the repetition frequency was 330 kHz; by adjusting the Z-axis height of the processing platform, the defocus amount of the sample surface to be flattened relative to the laser focus spot was made to be 500 μm.

[0102] (6) Polishing and flattening the surface of magnetron sputtered Au film

[0103] The processing platform is moved horizontally, and the starting point of the processing is located with the help of the guiding red light emitted by the scanning galvanometer, and the protective gas device and the dust suction device are turned on; the type of protective gas is pure argon, and the protective gas flow rate is 20L / min; the laser is turned on in the laser and scanning galvanometer control software, and it is scanned according to the pre-set processing trajectory, scanning path and processing parameters, and the surface of the magnetron sputtered Au film is polished and flattened.

[0104] (7) Post-processing of samples

[0105] After completing the specified processing trajectory, scanning path and processing times, the laser stops emitting light, the protective gas device and dust removal device are turned off, and the first polishing and flattening process is completed. The processed samples are ultrasonically cleaned with anhydrous ethanol for 25 minutes, and then ultrasonically cleaned with deionized water; the cleaned samples are placed on a constant temperature heating table for drying. The temperature of the constant temperature heating table is set to 60°C, and the drying time is 2 minutes.

[0106] (8) Observation of the microscopic morphology of the magnetron sputtered Au film surface after treatment

[0107] The microscopic morphology of the magnetron sputtered Au film surface of the sample obtained in step (7) was photographed using a scanning electron microscope and an atomic force microscope, the distribution of undulating features such as burrs and particles was observed, and the roughness of the film surface after polishing and flattening was measured; the test results are as follows: Figure 2 (b) and shown Figure 3 As shown in (b), Figure 2 (b) It can be seen that after ultrafast laser polishing and flattening treatment, the burrs, particles and other fluctuations on the surface of the magnetron sputtered Au film of the sample are significantly reduced, and the surface quality of the film is significantly improved; Figure 3 (b) It can be seen that after ultrafast laser polishing and flattening treatment, the surface roughness of the Au film is reduced to 1.20 nm, and the number and sharpness of the surface burr features are significantly reduced.

[0108] (9) Test the mechanical and tribological properties of the samples

[0109] The mechanical and tribological properties of the magnetron sputtered Au thin film sample obtained in step (7) were tested; the mechanical properties of the magnetron sputtered Au thin film sample were tested using a nanoindenter (the downward pressure load used was 1 mN and the holding time was 5 s), and the following results were obtained: Figure 4 The penetration depth-loading force curve is shown in Figure 2. Figure 4It can be seen that under the same pressing load and holding time conditions, the maximum indentation depth of the original Au film is 108 nm, while that of the Au film after ultraviolet femtosecond laser polishing and planarization treatment is reduced to 99 nm, indicating that the surface hardness of the magnetron sputtered Au film after ultraviolet femtosecond laser polishing and planarization treatment has been improved. When the femtosecond laser irradiates the surface of the Au film, burrs and particles in the irradiated area quickly evaporate to form a plasma. The formed plasma expands rapidly, generating a high-pressure shock wave, applying compressive stress to the surface of the film material and causing a small amount of plastic deformation on the surface layer, increasing the dislocation density on the film surface layer, and thus improving the surface hardness. According to the test results of nanoindentation, the thickness of the surface hardened layer is less than 100 nm. In addition, tribological performance tests were carried out using an atomic force microscope; a graphite island with a size of 6 μm × 6 μm was transferred onto the surface of the planarized Au film using a nano manipulator. The upper surface of the graphite island is covered with a 200-nm-thick Pt island cover. An XYZ piezoelectric scanning tube is installed on the sample stage inside the atomic force microscope. The test sample carrying the graphite island is fixed on the piezoelectric scanning tube, and the graphite island on the upper layer of the sample is pressed by the probe of the atomic force microscope. After the test starts, the piezoelectric scanning tube drives the Au film under the sample to reciprocate horizontally, causing the Au film-graphite island friction pair to perform periodic relative motion, and the single stroke of the displacement is 2 μm. The frictional force between the Au film and the graphite island will cause the cantilever beam of the atomic force microscope probe to twist and deform. By detecting the degree of deformation and calibrating through software, the frictional force between the Au film and the graphite island can be obtained. As Figure 5 shown, by applying different downward pressures to the graphite island, the frictional force under different loads can be obtained, and the friction coefficient of the Au film-graphite island friction pair can be obtained through linear fitting. As Figure 5 shown in the friction coefficient fitting curve, the friction coefficient between the original Au film and the graphite island is 0.03458 ± 0.00228, and the friction coefficient between the Au film after ultraviolet femtosecond laser polishing and planarization treatment and the graphite island is reduced to 0.00964 ± 0.00122.

[0110] In this embodiment, ultraviolet femtosecond laser is used for non-contact polishing and planarization treatment of the magnetron sputtered Au film, which can effectively remove uneven features such as burrs and particles on the surface of the magnetron sputtered Au film, reduce the surface roughness. At the same time, it can also improve the surface hardness and wear resistance of the magnetron sputtered Au film, thereby enhancing the tribological performance of the magnetron sputtered Au film. The friction coefficient between the magnetron sputtered Au film before treatment and the graphite island is 0.03458 ± 0.00228, and the friction coefficient between the magnetron sputtered Au film after ultraviolet femtosecond laser planarization treatment and the graphite island is reduced to 0.00964 ± 0.00122.

[0111] Comparative Example 1

[0112] The method of polishing and planarization in this comparative example is only different from that in Example 1 in that this comparative example uses a nanosecond laser (pulse width is 50 ns); the remaining steps are carried out with reference to the method in Example 1. Figure 6 Shown is the scanning electron microscope photograph of the surface morphology of the Au thin film after single-pass laser scanning. Compared with Example 1, the thermal effect caused by the 50-ns laser in this comparative example is significantly enhanced, and the Au thin film in the laser irradiation area ( Figure 6 the middle black strip area) is damaged and cracked, and even the underlying Si substrate is exposed. At the same time, under the ablation effect of the nanosecond laser, the substrate material is vaporized and deposited on the film surface in the form of particles, increasing the surface roughness of the film from the original 6.15 nm to 18 nm. At the same time, a thermal affected zone with a width of about 100 μm is formed on both sides of the laser irradiation area, and the mechanical properties of the Au thin film in the thermal affected zone will decline.

[0113] Comparative Example 2

[0114] The method of polishing and planarization in this comparative example is only different from that in Example 1 in that this comparative example uses a nanosecond laser (pulse width is 20 ns); the remaining steps are carried out with reference to the method in Example 1. Figure 7 Shown are the scanning electron microscope and atomic force microscope photographs of the surface morphology of the Au thin film after laser scanning. Compared with Example 1, the thermal effect caused by the 20-ns laser in this comparative example is still relatively significant, and many ablation pits are formed on the surface of the Au thin film, and many powder particles are deposited around the ablation pits, resulting in an increase in the surface roughness of the film to 29.94 nm.

[0115] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "example", "specific example", "some implementation schemes" or "some examples", etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0116] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for polishing and planarizing a thin film material, characterized in that: The following steps are involved: Ultrafast laser processing of thin film materials; The parameters of the ultrafast laser processing are: the wavelength of the ultrafast laser is 100 to 2000 nm, and the pulse width of the ultrafast laser is 1 fs to 1 ns; The thickness of the thin film material is 1 nm to 1000 μm.

2. The method for polishing and planarizing a thin film material according to claim 1, characterized in that: The roughness of the film material is 1 nm to 100 μm.

3. The method for polishing and planarizing a thin film material according to claim 1, characterized in that: The pulse frequency of ultrafast laser is 1kHz~1GHz.

4. The method for polishing and planarizing a thin film material according to claim 1, characterized in that: The power of ultrafast laser is 1mW~1kW.

5. The method for polishing and planarizing a thin film material according to claim 1, characterized in that: The defocus range of ultrafast laser is 0 to 10,000 μm.

6. The method for polishing and planarizing a thin film material according to claim 1, characterized in that: The scanning filling line spacing of the ultrafast laser is 1 to 100 μm.

7. The method for polishing and planarizing a thin film material according to claim 1, characterized in that: The scanning speed of ultrafast laser is 1 to 10000 mm / s.

8. The method for polishing and planarizing a thin film material according to claim 1, characterized in that: The number of scans of the ultrafast laser is 1 to 1000 times.

9. The method for polishing and planarizing a thin film material according to claim 1, characterized in that: The film material includes a metal film and / or an inorganic non-metal film.

10. The method for polishing and planarizing a thin film material according to claim 1, characterized in that: The ultrafast laser processing is carried out in the presence of air or protective gas; Furthermore, the protective gas includes one or more of argon, helium or nitrogen.

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