Annealing-free low-stress low-resistivity composite film and preparation method and application thereof

Abstract

The invention discloses an annealing-free low-stress low-resistivity composite film and a preparation method and application thereof.The composite film is composed of a multi-layer composite metal intermediate layer and a gold film, the multi-layer composite metal intermediate layer is deposited on a substrate through pulse magnetron sputtering, the first layer of the multi-layer composite metal intermediate layer is a Cr layer, and the second layer of the multi-layer composite metal intermediate layer is Pt, Ir, Os, Ru, Mo, Ta, W or Re; high surface migration energy and sufficient surface migration time can be provided for deposited atoms by adopting a pulse magnetron sputtering technology, and the prepared composite film has the advantages of large grains, low defects, low resistivity performance, more compact structure, smaller surface roughness, better conductivity, better optical performance, lower stress and the like; the method can be applied to navigation devices and micro-nano optoelectronic devices, can effectively solve the problem that the Q value is greatly reduced after the hemispherical harmonic oscillator is metalized, or can be used for preparing ultra-compact and high-integration high-performance micro-nano optoelectronic devices, is suitable for industrial production, and has great application prospects.

Description

Technical Field

[0001] The present invention relates to a composite film, and in particular to a non-annealed low-stress low-resistivity composite film, and also relates to a preparation method and application of the above non-annealed low-stress low-resistivity composite film. Background Art

[0002] The hemispherical resonant gyroscope is a new type of solid gyroscope based on the Coriolis vibration principle, and has many advantages such as simple structure, small size, light weight, low energy consumption, high reliability, and long working life. It is widely used in many fields such as aerospace, ships, automotive safety, and geophysical mapping. With the development of the aerospace and aviation industries, the demand for inertial instruments with stable physical properties, high alignment accuracy, and long-term drift stability in China is increasing day by day, posing various challenges to the research and development of hemispherical resonant gyroscopes. The hemispherical resonant gyroscope is processed from fused quartz material with a high quality factor Q, and its core component is the hemispherical gyro resonator. The quality factor Q is a key parameter for evaluating the performance of the quartz resonator. The higher the quality factor, the lower the internal loss performance of the material. It is found that the surface loss and thermoelastic damping of the gyroscope have the greatest influence on the quality factor, and the support damping also has a certain influence. It is difficult to completely eliminate these damping effects by process means, and only continuous process optimization or material selection can be carried out to reduce their influence on the mechanical quality factor.

[0003] The hemispherical resonator is installed on the base of the gyroscope, and the measurement of the rotation angle is realized through electrostatic drive and detection. Since the conductivity of the fused quartz material is very poor, it is necessary to coat the surface of the hemispherical resonator made of fused quartz material to make it have conductive properties. However, the quality factor often drops to a large extent after coating, so there are relatively strict requirements for the coating process conditions, the thickness, purity, and adhesion of the metal film. At the same time, it is found that the metallization coating process of the hemispherical resonator can directly determine the vibration characteristics of the gyroscope, thereby affecting the accuracy and performance of the resonator. Therefore, how to obtain a dense film with low resistivity, low residual stress, and adhesion through a good preparation process is the key content to be solved urgently.

[0004] The traditional surface coating process of the hemispherical resonator is generally the DC magnetron sputtering or evaporation process. Due to the low energy of the deposited atoms and the low substrate temperature, the microstructure of the film is loose, the film grains are fine, and the film resistivity is high. Generally, the resistivity of the gold film prepared by DC magnetron sputtering or vacuum evaporation is 7×10 -8Around Ωm. The resistivity of the gold thin film will affect the reliability of signal vibration. In addition, coating the surface of the hemispherical resonator will strongly affect the Q value of the hemispherical resonator, often resulting in a 20%-50% reduction. Among them, the higher the Q value of the hemispherical resonator, the greater the reduction. Although heat treatment after coating will improve the conductivity, reduce some defects, and thus recover part of the Q value reduction, annealing treatment at 200-300 °C will introduce higher thermal stress, generate new defects and internal friction of the resonator. Therefore, the surface metallization process of the hemispherical resonator is still the key bottleneck restricting the improvement of the Q value of the hemispherical resonator. It is urgent to develop new preparation technologies to improve the density, surface flatness of the metal thin film, increase the grain size, reduce the resistivity of the gold thin film, reduce the number of defects induced by annealing thermal stress, and reduce the internal friction of the resonator, so as to further improve the vibration accuracy of the resonator. Summary of the Invention

[0005] Object of the Invention: The present invention provides a non-annealed low-stress and low-resistivity composite thin film with high density, smooth surface, large grains, few defects, low stress, good conductivity and good optical properties, and also provides a preparation method and application of the above non-annealed low-stress and low-resistivity composite thin film.

[0006] Technical Solution: The non-annealed low-stress and low-resistivity composite thin film described in the present invention is composed of a multi-layer composite metal intermediate layer and a gold thin film deposited on a substrate by magnetron sputtering. The materials of the multi-layer composite metal intermediate layer include Cr, Pt, Ir, Os, Ru, Mo, Ta, W and Re.

[0007] Among them, the first layer of the multi-layer composite metal intermediate layer is a Cr layer, the second layer is Pt, Ir, Os, Ru, Mo, Ta, W and Re, and the purity of the target used for preparing the multi-layer composite intermediate layer is greater than 99.99%. The thickness of the first Cr layer is 5-20 nm, and the thickness of the second layer is 5-20 nm.

[0008] Among them, the purity of the gold thin film is greater than 99.999%, and the thickness is 100-200 nm; the grain size can be as high as 300-400 nm without high-temperature heat treatment (200-300 °C), and the stress can be as low as -45 MPa.

[0009] The preparation method of the above non-annealed low-stress and low-resistivity composite thin film includes the following steps:

[0010] (1) Ultrasonically clean the substrate sample.

[0011] (2) Fix the cleaned substrate sample on the magnetron sputtering instrument table and evacuate to below 6×10 -4 Pa.

[0012] (3) Introduce Ar gas, and on the surface of the cleaned substrate sample, with a power density of 1-9 W / cm -2A sputtering target is used to obtain a multi-layer composite metal intermediate layer;

[0013] (4) Using pulsed deposition technology, a gold film is sputter-deposited on the surface of the multi-layer composite metal intermediate layer prepared in step (3), and the working gas is Ar, thus obtaining an annealing-free low-stress low-resistivity composite film.

[0014] Among them, in step (1), the cleaning is sequentially carried out with acetone, ethanol and deionized water. The ultrasonic conditions are room temperature, the frequency is 20 - 200 kHz, and the time is 5 - 20 minutes.

[0015] Among them, in step (3), the Ar gas flow rate is 1 * 0 - 50 sccm, the working pressure is 0.1 - 5 Pa, and the average power density is maintained at 0.14 - 2 W / cm 2 .

[0016] Among them, in step (4), the gold film flow rate is 0 - 50 sccm, the working pressure is 0.1 - 5 Pa, and the average power density is maintained at 0.14 - 1 W / cm 2 , the peak power density is 0.01 - 0.09 kW / cm 2 , the frequency is 100 - 600 Hz, the pulse width is 25 - 100 us; the deposition time is 120 - 2200 s, and the deposition temperature is 25 - 150 °C.

[0017] The present invention also discloses the application of the above annealing-free low-stress low-resistivity composite film in navigation devices and micro-nano optoelectronic devices, specifically in fields such as hemispherical resonant gyroscopes for navigation, optical imaging and spectral analysis, nano-photonics and quantum optics, biosensing and diagnostics, chemical catalysis and reactions, etc.

[0018] Among them, the annealing-free low-stress low-resistivity composite film is applied to coat the surface of the resonator of the hemispherical resonant gyroscope.

[0019] Principle of the invention: The annealing-free low-stress low-resistivity composite film of the present invention is composed of a multi-layer metal intermediate layer and a gold film deposited on a substrate by magnetron sputtering. Among them, Cr is specifically selected as the first layer of the multi-layer composite metal intermediate layer, and Pt, Ir, Os, Ru, Mo, Ta, W and Re are selected as the second layer.

[0020] Among them, the reason for selecting Cr is that Cr and the O element on the surface of silicon dioxide are prone to chemical bonding, strengthening the combination of the two. At the same time, the easy alloying between Cr and the second-layer metal also results in good combination of the two. The reason for using Pt, Ir, Os, Ru, Mo, Ta, W and Re as the second layer is that the surface energies of Pt, Ir, Os, Ru, Mo, Ta, W and Re are about 3.0 J / m 2 、3.0 J / m 2, 3.0 J / m 2 , 2.9 J / m 2 , 2.7 J / m 2 , 2.8 J / m 2 , 3.0 J / m 2 , 2.9 J / m 2 , much higher than the surface energy of Au, 2.5 J / m 2 , according to the Young's equation of contact angle, if the influence of the interfacial energy between metals is ignored, Au grains with relatively low surface energy tend to spread on the surfaces of Pt, Ir, Os, Ru, Mo, Ta, W, and Re with high surface energy, and the grains tend to grow in a layered growth mode. In the traditional process, Au is generally directly deposited on the surface of the Cr intermediate layer. Since the surface energy of Cr is about 2.3 J / m 2 , lower than the surface energy of Au, the deposition of Au on the Cr surface tends to grow in an island mode.

[0021] The design of the second metal layer of the above intermediate layer is based on the thermodynamic analysis. However, from the kinetic perspective, the situation is more complex: on the one hand, if the energy of the deposited Au atoms is too low, the Au atoms cannot effectively migrate on the grain surface, which will promote the nucleation process, resulting in grain refinement. The defects in the deposition process cannot be eliminated in time, leading to problems such as the generation of micro-stress and the increase of internal friction. On the other hand, if the deposition rate is too fast, the deposited Au atoms cannot migrate to the proper position on the thin film in time and will be covered by the subsequent deposited atoms, which will also promote the nucleation process, resulting in grain refinement. The defects in the deposition process cannot be eliminated in time, leading to problems such as the generation of micro-stress and the increase of internal friction. Therefore, in this patent, through the magnetron sputtering method, pulsed deposition is carried out. During the deposition stage, the sputtering power density is increased or the deposition temperature is appropriately increased to improve the energy of the deposited Au atoms and promote their ability to fully migrate on the thin film surface. By controlling the ratio of the deposition and non-deposition periods within one cycle (which can be regulated by the sputtering pulse width and sputtering frequency), the deposition rate of Au atoms and the free migration time of Au are controlled, so that the deposited Au atoms have enough time to fully migrate on the thin film surface before being covered.

[0022] Therefore, only through the above design of the thin film composition structure (from the thermodynamic perspective) and the design of the deposition process parameters (from the kinetic perspective), through the synergistic effect of the two, can nucleation be reduced, the growth of grains along the horizontal direction of the thin film be promoted, the grain boundary and intra-grain defects be reduced, the surface roughness be reduced, the resistivity be reduced, and the stress be reduced. It also avoids the problems of increasing process steps and thermal stress caused by post-heat treatment. Since the resistivity of the intermediate layer is much greater than that of the Au layer, an overly thick intermediate layer cannot improve the overall performance (electrical performance) of the composite thin film and often instead reduces the performance of the device (such as the quality factor Q of the resonator). Therefore, the present invention adopts a suitable design of the intermediate layer thickness and combines the optimization of various improvement points to obtain a composite thin film with excellent performance, free of annealing, low stress, and low resistivity.

[0023] Beneficial effects: Compared with the prior art, the present invention has the following remarkable advantages:

[0024] (1) Compared with the traditional metallization process (such as DC magnetron sputtering DCMS) and the traditional Au thin film structure (mainly Cr layer + Au layer), the annealing-free low-stress low-resistivity composite film of the present invention is denser, has a smaller surface roughness, larger grains, better conductivity, better optical properties, fewer defects, lower stress, and does not require the annealing process required by the traditional process; its resistivity is as low as 3.4×10 -8 Ωm; the grain boundary reflection coefficient is as low as 0.275, the bonding force with the substrate is as high as 9.7 N, the optical reflectivity is as high as 96% (800 nm) / 38% (400 nm), and the stress is as low as -45 MPa;

[0025] (2) Compared with the traditional metallization process (such as DC magnetron sputtering DCMS), the pulsed magnetron sputtering technology can not only provide a higher ionization rate and ion energy of the deposited atoms, but also give the deposited atoms more free migration time on the film surface, which is beneficial to the growth of high-quality films;

[0026] (3) The annealing-free low-stress low-resistivity composite film of the present invention is applied to micro-nano optoelectronic devices, which can effectively improve the problem of a large decrease in the Q value after the metallization of the hemispherical resonator, and can produce ultra-compact, highly integrated high-performance micro-nano optoelectronic devices, which have great application prospects. Description of the drawings

[0027] Figure 1 is the surface morphology of the annealing-free low-stress low-resistivity composite film in Example 1;

[0028] Figure 2 is the 3D surface morphology of the annealing-free low-stress low-resistivity composite film in Example 1;

[0029] Figure 3 is the stress measurement data of the annealing-free low-stress low-resistivity composite film in Example 1 by XRD method;

[0030] Figure 4 is the scratch test photo of the annealing-free low-stress low-resistivity composite film in Example 1;

[0031] Figure 5 is the reflection spectrum of the annealing-free low-stress low-resistivity composite film in Example 1;

[0032] Figure 6 is the surface morphology of the annealing-free low-stress low-resistivity composite film in Example 2;

[0033] Figure 7The 3D surface morphology of the non-annealed low-stress and low-resistivity composite film in Example 2;

[0034] Figure 8 The stress measurement data of the non-annealed low-stress and low-resistivity composite film in Example 2 by XRD method;

[0035] Figure 9 The scratch test photo of the non-annealed low-stress and low-resistivity composite film in Example 2;

[0036] Figure 10 The reflection spectrum of the non-annealed low-stress and low-resistivity composite film in Example 2;

[0037] Figure 11 The surface morphology of the non-annealed low-stress and low-resistivity composite film in Example 3;

[0038] Figure 12 The 3D surface morphology of the non-annealed low-stress and low-resistivity composite film in Example 3;

[0039] Figure 13 The stress measurement data of the non-annealed low-stress and low-resistivity composite film in Example 3 by XRD method;

[0040] Figure 14 The scratch test photo of the non-annealed low-stress and low-resistivity composite film in Example 3;

[0041] Figure 15 The reflection spectrum of the non-annealed low-stress and low-resistivity composite film in Example 3;

[0042] Figure 16 The surface morphology of the non-annealed low-stress and low-resistivity composite film in Example 4;

[0043] Figure 17 The 3D surface morphology of the non-annealed low-stress and low-resistivity composite film in Example 4;

[0044] Figure 18 The stress measurement data of the non-annealed low-stress and low-resistivity composite film in Example 4 by XRD method;

[0045] Figure 19 The scratch test photo of the non-annealed low-stress and low-resistivity composite film in Example 4;

[0046] Figure 20 The reflection spectrum of the non-annealed low-stress and low-resistivity composite film in Example 4;

[0047] Figure 21 The surface morphology of the non-annealed low-stress and low-resistivity composite film in Example 5;

[0048] Figure 223D surface topography of the annealing-free low-stress and low-resistivity composite film in Example 5;

[0049] Figure 23 XRD method stress measurement data of the annealing-free low-stress and low-resistivity composite film in Example 5;

[0050] Figure 24 Scratch test photos of the annealing-free low-stress and low-resistivity composite film in Example 5;

[0051] Figure 25 Reflection spectrum of the annealing-free low-stress and low-resistivity composite film in Example 5;

[0052] Figure 26 Surface topography of the annealing-free low-stress and low-resistivity composite film in Example 6;

[0053] Figure 27 Comparison of resistivity (Figure a) and stress (Figure b) between the Au film prepared by DC sputtering in Comparative Example 1 and the annealing-free low-stress and low-resistivity composite films prepared by pulsed sputtering in Examples 1 and 4;

[0054] Figure 28 Surface topography of the film in Comparative Example 2;

[0055] Figure 29 Surface topography of the film in Comparative Example 3;

[0056] Figure 30 Surface topography of the film in Comparative Example 4;

[0057] Figure 31 Surface topography of the film in Comparative Example 5;

[0058] Figure 32 Surface topography of the film in Comparative Example 6. Detailed implementation mode

[0059] The technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. The test materials used in the embodiments can be obtained through conventional channels.

[0060] Example 1

[0061] The preparation method of the annealing-free low-stress and low-resistivity composite film of the present invention specifically includes the following steps:

[0062] (1) Using molten silica as the substrate, ultrasonically clean it in acetone, ethanol, and deionized water in sequence; the ultrasonic conditions are room temperature, the frequency is 20 kHz, and the time is 5 minutes.

[0063] (2) Fix the cleaned substrate sample on the magnetron sputtering instrument stage, evacuate to 6×10 -4Below Pa;

[0064] (3) Introduce Ar gas with a flow rate of 10 sccm and a working pressure of 0.1 Pa, and deposit the metal intermediate layer Cr to 5 nm at a power density of 0.14 W / cm -2 Deposit the metal intermediate layer W to 20 nm at a power density of 0.14 W / cm -2 Deposit the metal intermediate layer W to 20 nm;

[0065] (4) Deposit the Au thin film by pulsed sputtering. The working gas is Ar with a flow rate of 10 sccm and a working pressure of 0.1 Pa. Maintain an average power density of 3 W / cm 2 and a peak power density of 0.06 kW / cm 2 , a frequency of 500 Hz, and a pulse width of 100 μs; the deposition time is 120 s and the deposition temperature is 25 °C; thus, the annealing-free low-stress low-resistivity composite thin film of the present invention is obtained; the thickness of the Au thin film is 100 nm.

[0066] The Au film prepared in Example 1 was observed by scanning electron microscopy (as Figure 1 ), and it has a flat and dense structure with particle sizes of about 50 - 100 nm, showing a cellular structure. The surface roughness obtained by atomic force microscopy is 0.67 nm (as Figure 2 ); the film stress measured by X-ray diffractometer is -45 Mpa (as Figure 3 ); the critical load measured by a scratch tester is 8.8 N (as Figure 4 ); the film reflectance obtained by a spectrophotometer is 91% (800 nm) / 37% (400 nm) (as Figure 5 ); the resistivity obtained by a four-probe instrument is 4.5×10 -8 Ω·m; the grain boundary reflection coefficient obtained by formula 1 is 0.275.

[0067]

[0068] where D is the grain size, R is the grain boundary scattering coefficient, ρ0 represents the resistivity of the bulk metal material, and ρ is the measured resistivity; the value of R ranges from 0 to 1, representing that electrons pass completely and are completely scattered, respectively.

[0069] Example 2

[0070] For the annealing-free low-stress low-resistivity composite thin film of the present invention, the preparation method specifically includes the following steps:

[0071] (1) Use molten silica as the substrate and ultrasonically clean it successively in acetone, ethanol, and deionized water; the ultrasonic conditions are room temperature, a frequency of 200 kHz, and a time of 20 minutes.

[0072] (2) Fix the cleaned substrate sample on the magnetron sputtering instrument stage and evacuate to below 6×10 -4 Pa;

[0073] (3) Introduce Ar gas with a flow rate of 50 sccm and a working pressure of 5 Pa, and deposit the metal intermediate layer Cr to 20 nm at a power density of 2 W / cm -2 , and deposit the metal intermediate layer Pt to 20 nm at a power density of 2 W / cm -2 ;

[0074] (4) Deposit the Au film by pulsed sputtering. The working gas is Ar with a flow rate of 30 sccm and a working pressure of 0.5 Pa. Maintain an average power density of 0.6 W / cm 2 , a peak power density of 0.06 kW / cm 2 , a frequency of 500 Hz, and a pulse width of 25 μs; the deposition time is 240 s and the deposition temperature is 25 °C; thus obtaining the annealing-free low-stress low-resistivity composite film of the present invention with a film thickness of 120 nm.

[0075] The Au film prepared in Example 2 was observed by scanning electron microscopy (as Figure 6 ), and it has a flat and dense structure with particle sizes of about 5 - 10 nm, showing a cellular structure. The surface roughness obtained by atomic force microscopy is 0.87 nm (as Figure 7 ); the film stress measured by X-ray diffractometer is -300 Mpa (as Figure 8 ); the critical load measured by a scratch tester is 9.7 N (as Figure 9 ); the film reflectance obtained by a spectrophotometer is 89% (800 nm) / 37% (400 nm) (as Figure 10 ); the resistivity obtained by a four-probe instrument is 10×10 -8 Ω·m; the grain boundary reflection coefficient obtained by formula 1 is 0.467.

[0076] Example 3

[0077] For the annealing-free low-stress low-resistivity composite film of the present invention, its preparation method specifically includes the following steps:

[0078] (1) Use molten silica as the substrate and ultrasonically clean it in acetone, ethanol, and deionized water in sequence; the ultrasonic conditions are room temperature, a frequency of 100 kHz, and a time of 15 minutes.

[0079] (2) Fix the cleaned substrate sample on the magnetron sputtering instrument stage and evacuate to below 6×10 -4 Pa;

[0080] (3) Introduce Ar gas with a flow rate of 30 sccm and a working pressure of 0.5 Pa, and deposit the metal intermediate layer Cr to 10 nm at a power density of 2 W / cm -2 Deposit the metal intermediate layer Ta to 5 nm at a power density of 2 W / cm -2 ;

[0081] (4) Deposit the Au film by pulsed sputtering. The working gas is Ar with a flow rate of 30 sccm and a working pressure of 0.5 Pa. Maintain an average power density of 0.6 W / cm 2 and a peak power density of 0.06 kW / cm 2 , with a frequency of 100 Hz and a pulse width of 50 μs; the deposition time is 480 s and the deposition temperature is 25 °C; thus, the annealing-free low-stress low-resistivity composite film of the present invention is obtained, and the film thickness is 120 nm.

[0082] The Au film prepared in Example 3 was observed by scanning electron microscopy (as shown in Figure 11 ), and it has a flat and dense structure with a particle size of about 10 - 20 nm, showing a cellular structure. The surface roughness obtained by atomic force microscopy is 0.53 nm (as shown in Figure 12 ); the film stress measured by X-ray diffractometer is -600 Mpa (as shown in Figure 13 ); the critical load measured by a scratch tester is 5.9 N (as shown in Figure 14 ); the film reflectance obtained by a spectrophotometer is 93% (800 nm) / 37% (400 nm) (as shown in Figure 15 ); the resistivity obtained by a four-probe instrument is 6×10 -8 Ω·m; the grain boundary reflection coefficient obtained by formula 1 is 0.382.

[0083] Example 4

[0084] For the annealing-free low-stress low-resistivity composite film of the present invention, its preparation method specifically includes the following steps:

[0085] (1) Use molten silica as the substrate and ultrasonically clean it in acetone, ethanol, and deionized water in sequence; the ultrasonic conditions are at room temperature, with a frequency of 100 kHz and a time of 15 minutes.

[0086] (2) Fix the cleaned substrate sample on the magnetron sputtering instrument stage and evacuate to below 6×10 -4 Pa;

[0087] (3) Introduce Ar gas with a flow rate of 30 sccm and a working pressure of 0.5 Pa, and deposit the metal intermediate layer Cr to 5 nm at a power density of 0.1 W / cm -2 Deposit the metal intermediate layer Ta to 5 nm at a power density of 0.14 W / cm -2Deposit a metal intermediate layer Mo to 20 nm;

[0088] (4) Use a high-energy pulsed power supply to sputter-deposit an Au film. The working gas is Ar, the flow rate is 30 sccm, the working pressure is 0.5 Pa, maintain an average power density of 1 W / cm 2 , and a peak power density of 0.09 kW / cm 2 , with a frequency of 500 Hz and a pulse width of 75 us; the deposition time is 200 s and the deposition temperature is 25 °C; thus obtaining the annealing-free low-stress low-resistivity composite film of the present invention, with a film thickness of 120 nm.

[0089] The Au film prepared in Example 4 was observed by scanning electron microscopy (as Figure 16 ), and it has a flat and dense structure, with particle sizes around 20 - 50 nm, showing a cellular structure. The surface roughness obtained by atomic force microscopy is 1.02 nm (as Figure 17 ); the film stress measured by X-ray diffractometer is -350 Mpa (as Figure 18 ); the critical load measured by a scratch tester is 6.7 N (as Figure 19 ); the film reflectance obtained by a spectrophotometer is 90% (800 nm) / 36% (400 nm) (as Figure 20 ); the resistivity obtained by a four-probe instrument is 6.4×10 -8 Ωm; the grain boundary reflection coefficient obtained by formula 1 is 0.388.

[0090] Example 5

[0091] The preparation method of the annealing-free low-stress low-resistivity composite film of the present invention specifically includes the following steps:

[0092] (1) Use molten silica as the substrate and ultrasonically clean it in acetone, ethanol, and deionized water in sequence; the ultrasonic conditions are room temperature, a frequency of 100 kHz, and a time of 15 minutes.

[0093] (2) Fix the cleaned substrate sample on the magnetron sputtering instrument stage and evacuate to below 6×10 -4 Pa;

[0094] (3) Introduce Ar gas, with an Ar gas flow rate of 30 sccm and a working pressure of 0.5 Pa, deposit a metal intermediate layer Cr to 10 nm at a power density of 0.5 W / cm -2 , and deposit a metal intermediate layer Ir to 20 nm at a power density of 0.5 W / cm -2 ;

[0095] (4) Sputter-deposit the Au film using a high-energy pulsed power supply. The working gas is Ar with a flow rate of 50 sccm, the working pressure is 5 Pa, maintaining an average power density of 0.6 W / cm 2 , and a peak power density of 0.06 kW / cm 2 , with a frequency of 600 Hz and a pulse width of 75 us; the deposition time is 200 s and the deposition temperature is 25 °C; thus obtaining the annealing-free low-stress low-resistivity composite film of the present invention, with a film thickness of 120 nm.

[0096] The Au film prepared in Example 5 was observed by scanning electron microscopy (as shown in Figure 22 ), which has a flat and dense structure, with particle sizes around 20 - 50 nm, showing a cellular structure. The surface roughness obtained by atomic force microscopy is 1.07 nm (as shown in Figure 23 ); the film stress measured by X-ray diffractometer is -200 Mpa (as shown in Figure 24 ); the critical load measured by a scratch tester is 8.2 N (as shown in Figure 25 ); the film reflectance obtained by a spectrophotometer is 95% (800 nm) / 35% (400 nm) (as shown in Figure 26 ); the resistivity obtained by a four-probe instrument is 8.7×10 -8 Ωm; the grain boundary reflection coefficient obtained by formula 1 is 0.44.

[0097] Example 6

[0098] For the annealing-free low-stress low-resistivity composite film of the present invention, its preparation method specifically includes the following steps:

[0099] (1) Use molten silica as the substrate and ultrasonically clean it successively in acetone, ethanol, and deionized water; the ultrasonic conditions are room temperature, a frequency of 100 kHz, and a time of 15 minutes.

[0100] (2) Fix the cleaned substrate sample on the magnetron sputtering instrument stage and evacuate to below 6×10 -4 Pa;

[0101] (3) Introduce Ar gas with an Ar gas flow rate of 30 sccm and a working pressure of 0.5 Pa, and deposit the metal intermediate layer Cr to 5 nm at a power density of 0.5 W / cm -2 , and deposit the metal intermediate layer W to 20 nm at a power density of 0.5 W / cm -2 ;

[0102] (4) Use pulsed sputtering to deposit the Au film. The working gas is Ar with a flow rate of 30 sccm and a working pressure of 0.5 Pa, maintaining an average power density of 0.14 W / cm 2 , and a peak power density of 0.01 kW / cm2 At a frequency of 500 Hz and a pulse width of 50 μs; the deposition time is 2200 s and the deposition temperature is 150 °C; thus, the annealing-free low-stress low-resistivity composite film of the present invention is obtained, and the film thickness is 120 nm.

[0103] The Au film prepared in Example 6 was observed by scanning electron microscopy (as Figure 26 ), and it has a flat and dense structure. The particle size is about 400 - 500 nm. The large grain size results in fewer grain boundary defects; the surface roughness is 1.2 nm; the resistivity obtained by a four-probe instrument is 3.4×10 -8 Ωm.

[0104] Comparative Example 1

[0105] A composite Au film, and its preparation method includes the following steps:

[0106] (1) A Cr film was deposited on a SiO2 substrate by DC sputtering. The working gas was Ar, the flow rate was 30 sccm, the working pressure was 0.5 Pa, and the maintained power density was 0.5 W / cm 2 , the deposition temperature was 25 °C, and the film thickness was about 10 nm.

[0107] (2) Further, an Au film was deposited by DC sputtering. The working gas was Ar, the flow rate was 30 sccm, the working pressure was 0.5 Pa, and the maintained average power density was 0.5 W / cm 2 , the deposition time was 100 s, the deposition temperature was 25 °C, and the film thickness was about 150 nm.

[0108] (3) Further, the sample was treated at 300 °C for 20 minutes to obtain a composite Au film.

[0109] As Figure 27 shown, the resistivity and stress of the composite Au film obtained by DC sputtering are 7.1×10 -8 Ωm and -600 Mpa respectively, which are higher than the corresponding performance indexes of the annealing-free low-stress low-resistivity composite films prepared in Example 1 and Example 4. A high resistivity will cause the Au film with a specific resistance plated on the surface of the hemispherical resonator to require a greater thickness, and the increase in the thickness of the metal layer will lead to a decrease in the Q value of the resonator; at the same time, the increase in the film stress will also cause uneven deformation of the hemispherical resonator, which also leads to a decrease in the Q value of the resonator.

[0110] After the sample prepared by DC deposition in Comparative Example 1 was treated at 300 °C for 20 minutes, the stress of the composite Au film further increased to 900 Mpa. During the cooling process, since the expansion coefficient of Au is much larger than that of the substrate SiO2, the shrinkage of the Au film is much larger than that of the substrate SiO2. The substrate SiO2 restricts the shrinkage of the Au film, causing the Au film to generate a great tensile stress (which also belongs to thermal stress), affecting the subsequent applications.

[0111] Comparative Example 2

[0112] A composite Au film, and its preparation method includes the following steps:

[0113] (1) A Cr film was deposited on a SiO2 substrate by DC sputtering. The working gas was Ar, the flow rate was 30 sccm, the working pressure was 0.5 Pa, and the maintained power density was 0.5 W / cm 2 , the deposition temperature was 150 °C, and the film thickness was about 10 nm.

[0114] (2) An Au film was deposited using a DC power supply. The working gas was Ar, the flow rate was 30 sccm, the working pressure was 0.5 Pa, and the maintained average power density was 0.5 W / cm 2 , the deposition time was 100 s, the deposition temperature was 150 °C, and the film thickness was about 200 nm, obtaining a composite Au film.

[0115] The composite Au film deposited by the DC power supply under the condition of 150 °C in Comparative Example 2 has particle sizes of about 10 - 100 nm, and is loose with a large number of pores and many grain boundary defects (such as Figure 28 ); the surface roughness is 3.2 nm. The resistivity is 6×10 -8 Ωm. While under the same temperature condition, the Au film prepared in Example 6 was observed by scanning electron microscope and has a denser structure, with particle sizes of about 400 - 500 nm. The large grains result in fewer grain boundary defects, and the surface roughness is 1.2 nm; the resistivity obtained by a four-probe instrument is 3.4×10 -8 Ωm. It can be seen that under the heating condition of deposition, the annealing-free low-stress low-resistivity composite film of the present invention can prepare a high-performance Au film with larger grains, smoother and denser compared with the traditional process.

[0116] Comparative Example 3

[0117] A composite Au film, and its preparation method includes the following steps:

[0118] (1) A Cr film was deposited on a SiO2 substrate by DC sputtering. The working gas was Ar, the flow rate was 30 sccm, the working pressure was 0.5 Pa, and the maintained power density was 0.5 W / cm 2 , the deposition temperature was 25 °C, and the film thickness was about 10 nm.

[0119] (2) An Au film was deposited using a DC power supply. The working gas was Ar, the flow rate was 30 sccm, the working pressure was 0.5 Pa, and the maintained power density was 0.14 W / cm 2 , the deposition temperature was 25 °C, and the film thickness was about 15 nm, obtaining a composite Au film.

[0120] As Figure 29 for the composite Au thin film deposited in Comparative Example 3, the particle size thereof is about 5 - 15 nm, the crystal grains are fine, and the resistivity obtained by a four-probe meter is 3.4×10 -8 Ωm.

[0121] Comparative Example 4

[0122] A composite Au thin film, the preparation method thereof comprises the following steps:

[0123] (1) A Cr thin film was deposited on a SiO2 substrate by DC sputtering. The working gas was Ar, the flow rate was 30 sccm, the working pressure was 0.5 Pa, the maintained power density was 0.5 W / cm 2 , the deposition temperature was 25°C, and the film thickness was about 10 nm.

[0124] (2) An Au thin film was deposited by pulse deposition technology. The working gas was Ar, the flow rate was 30 sccm, the working pressure was 0.5 Pa, the maintained power density was 0.14 W / cm 2 , the frequency was 200 Hz, the pulse width was 50 us, the deposition temperature was 25°C, and the film thickness was about 15 nm, obtaining the composite Au thin film.

[0125] As Figure 30 , many long strip-shaped holes appeared in the composite Au thin film deposited in Comparative Example 4, indicating that the island growth of the Au thin film was significant, and the film density and resistivity were inferior to those of Comparative Example 3 prepared by the traditional process. This was because the second metal layer design requirement of the present invention was not adopted for the intermediate layer, and the Au film was prepared by the deposition process of the present invention directly on the traditional Cr intermediate layer, which instead promoted the spheroidization (or dewetting) of the Au film, resulting in the film quality being worse than that of the Au film under the traditional structure and process.

[0126] Comparative Example 5

[0127] A composite Au thin film, the preparation method thereof comprises the following steps:

[0128] (1) A Cr thin film was deposited on a SiO2 substrate by DC sputtering. The working gas was Ar, the flow rate was 30 sccm, the working pressure was 0.5 Pa, the maintained power density was 0.14 W / cm 2 , the deposition temperature was 25°C, and the film thickness was about 20 nm.

[0129] (2) An Au thin film was deposited by DC power supply. The working gas was Ar, the flow rate was 30 sccm, the working pressure was 0.5 Pa, the maintained power density was 0.14 W / cm 2 , the deposition temperature was 25°C, and the film thickness was about 60 nm, obtaining the composite Au thin film.

[0130] As Figure 31 , for the Au thin film deposited in Comparative Example 5, its particle size is about 5 - 20 nm, and the resistivity obtained by a four-probe instrument is 8.5×10 -8 Ωm, and the stress is 400 MPa.

[0131] Comparative Example 6

[0132] A composite Au thin film, and its preparation method includes the following steps:

[0133] (1) A W thin film was deposited on a SiO2 substrate by DC sputtering. The working gas was Ar, the flow rate was 30 sccm, the working pressure was 0.5 Pa, and the maintained power density was 0.14 W / cm 2 , the deposition temperature was 25 °C, and the film thickness was about 20 nm.

[0134] (2) An Au thin film was deposited by a DC power supply. The working gas was Ar, the flow rate was 30 sccm, the working pressure was 0.5 Pa, and the maintained power density was 0.14 W / cm 2 , the deposition temperature was 25 °C, and the film thickness was about 60 nm, obtaining a composite Au thin film.

[0135] As Figure 32 , for the composite Au thin film deposited in Comparative Example 6, its particle size is about 20 - 50 nm, and the stress is 100 Mpa. The structure of Comparative Example 6 is slightly denser than that of Comparative Example 5, and the stress is lower, which reflects that the intermediate layer W in the present invention has a certain promoting effect on the layered growth of the Au layer. However, the resistivity obtained by a four-probe instrument is 7.4×10 -8 Ωm. Although the resistivity is slightly lower than that of Comparative Example 5, due to the absence of the deposition technology of the present invention, the diffusion of Au atoms on the film surface is still insufficient, and micro-defects are difficult to eliminate. Therefore, compared with Example 1, there are still large differences in indicators such as resistivity and stress. It shows that only under the condition of combining the design of the film composition structure and the film deposition technology can the synergistic effect be exerted to obtain excellent film properties.

[0136] Therefore, the annealing-free low-stress and low-resistivity gold thin film of the present invention can obtain large grains, low defects, and low-resistivity properties without annealing treatment, while avoiding the thermal stress induced by annealing and reducing the film-substrate interface defects and deformation defects caused by thermal stress. This highly conductive and low-defect gold thin film can be used in special scenarios such as the surface of gyro resonators or optoelectronic functional devices; its preparation process is simple, has strong scalability, and is suitable for industrial production.

Claims

1. A non-annealed low-stress and low-resistivity composite film, characterized in that, The annealing-free low-stress and low-resistivity composite film is composed of a multi-layer composite metal intermediate layer and a gold film deposited on a substrate by magnetron sputtering. The materials of the multi-layer composite metal intermediate layer include Cr, Pt, Ir, Os, Ru, Mo, Ta, W, and Re.

2. The non-annealed low-stress and low-resistivity composite thin film according to claim 1, wherein The substrate is molten silica.

3. The non-annealed low-stress low-resistivity composite film according to claim 1, wherein The first layer of the multi-layer composite metal intermediate layer is a Cr layer, and the second layer is Pt, Ir, Os, Ru, Mo, Ta, W, or Re. The purity of the target used for preparing the multi-layer composite intermediate layer is greater than 99.99%. The thickness of the first layer is 5 - 20 nm, and the thickness of the second layer is 5 - 20 nm.

4. The non-annealed low-stress low-resistivity composite film according to claim 1, wherein The purity of the target used for preparing the gold film is greater than 99.999%. The thickness of the gold film is 100 - 200 nm.

5. A method for preparing the non-annealed low-stress and low-resistivity composite film according to claim 1, characterized in that, It includes the following steps: (1) Ultrasonically clean the substrate sample; (2) Fix the cleaned substrate sample on the magnetron sputtering instrument stage and evacuate to below 6×10 -4 Pa; (3) Introduce Ar gas and sputter the target material on the surface of the cleaned substrate sample at a power density of 1-9 W / cm -2 to obtain a multi-layer composite metal intermediate layer; (4) Using pulsed deposition technology, sputter-deposit a gold film on the surface of the multi-layer composite metal intermediate layer obtained in step (3). The working gas is Ar, and the annealing-free low-stress and low-resistivity composite film is obtained.

6. The preparation method according to claim 5, characterized in that, In step (1), the cleaning is sequentially performed with acetone, ethanol, and deionized water. The ultrasonic conditions are room temperature, the frequency is 20 - 200 kHz, and the time is 5 - 20 minutes.

7. The preparation method according to claim 5, characterized in that, In step (3), the Ar gas flow rate is 10 - 50 sccm, the working pressure is 0.1 - 5 Pa, and the average power density is maintained at 0.14 - 2 W / cm 2 .

8. The preparation method according to claim 5, characterized in that, In step (4), the Ar gas flow rate is 10 - 50 sccm, the working pressure is 0.1 - 5 Pa, maintaining an average power density of 0.14 - 1 W / cm 2 , and a peak power density of 0.01 - 0.09 kW / cm 2 , the frequency is 100 - 600 Hz, the pulse width is 25 - 100 us; the deposition time is 120 - 2200 s, and the deposition temperature is 25 - 150 °C.

9. Application of the annealing-free low-stress and low-resistivity composite film according to claim 1 in navigation devices and micro-nano optoelectronic devices.

10. The application according to claim 9, characterized in that, The annealing-free low-stress and low-resistivity composite film is applied to coat the surface of the resonator of a hemispherical resonator gyroscope.

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