Mo-based multilayer film and preparation method and application thereof

Abstract

The invention belongs to the field of optical devices, and particularly relates to a Mo-based multilayer film and a preparation method and application thereof. The multilayer film comprises periodic low-Z material layers / high-Z material layers which are arranged in a stacked mode, the high-Z material is Mo, an interface between the low-Z material layer and the high-Z material layer which are adjacent to each other further comprises a MoxC1-x layer, and x is larger than 0 and smaller than 1. According to the method, a trace amount of methane gas is doped into working gas argon for magnetron sputtering, a layer of protective barrier can be formed on the interface of the high-Z material and the low-Z material by mixing the metal simple substance in the high-Z material of the absorption layer with the doped methane gas, and diffusion of the metal simple substance of the high-Z material and the low-Z material can be prevented. The protective barrier layer formed by the reaction of methane gas and Mo can inhibit crystallization of the high-Z material metal layer of the absorption layer at the same time, and the roughness of the interface can be reduced.

Description

Technical Field

[0001] The present invention belongs to the field of optical devices, and in particular relates to a Mo-based multilayer film and a preparation method and application thereof. Background Art

[0002] According to the Rayleigh criterion, reducing the wavelength of lithography light sources is a key path to advancing lithography technology to smaller process nodes. Today, the most advanced extreme ultraviolet (EUV) lithography systems have a wavelength of 13.5nm. Beyond 13.5nm, the optical systems in these lithography systems are all reflective, requiring the deposition of hundreds of layers of EUV multilayer reflective films, each just a few nanometers thick, on the optical lenses. Whether at the current 13.5nm wavelength or the next-generation 6.Xnm wavelength, or even shorter wavelengths, the development of high-performance reflective multilayer optical lenses and thin-film devices remains a bottleneck.

[0003] Since the multilayer film can reach hundreds of layers (13.5nm reflective multilayer film has about 100 layers, and 6.Xnm reflective multilayer film has about 500 layers), the quality of the multilayer film interface is a core factor that directly affects the optical performance of periodic multilayer mirrors (PMMs). Generally, this short-wavelength multilayer film is composed of two core main materials, namely the high-Z material of the absorption layer and the low-Z material of the scattering layer. The quality of the PMM interface mainly depends on the deposition quality of the two main materials of high-Z and low-Z that make up the multilayer film. Irregular crystallization during the deposition of high-Z materials leads to increased interface roughness, which is one of the main factors affecting spectral performance. Diffusion and mixing of high-Z and low-Z materials during the deposition process to form an interface mixture is another major factor affecting spectral performance.

[0004] To optimize the interface of PMMs, increase the reflectivity of the developed multilayer mirrors, and improve their spectral performance, further improvements are needed in the deposition of multilayer materials. Several innovative methods for improving interfaces have been proposed in existing references, such as "Proc. SPIE, 1992, pp. 221-227," "Opt. Express, 32 (2024) 26583-26595," and "Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 562 (2006) 389-392." Among these, adding a barrier layer at the interface of the multilayer to prevent direct contact between the two materials in the multilayer is a relatively effective approach. As early as 2002, Stefan BRAUN et al. pointed out in the paper “Japanese Journal of Applied Physics, 41 (2002) 4074” that the insertion of 0.3-0.5nm C and B4C barrier layers into Mo / Si multilayer films significantly improved the interface quality of Mo / Si multilayer films, and the EUV reflectivity increased from 68.7% to 71.4%. In 2020, Elena O. Filatova et al. pointed out in the document “The Journal of Physical Chemistry C, 124 (2020) 22601-22609” that the insertion of a B4C barrier layer into a Mo / Be multilayer film effectively reduced the total amount of beryllium generated at the interface and improved the quality of the interface layer of the Mo / Be multilayer film. However, with the insertion of the B4C barrier layer, MoB2 was generated at the Mo-on-B4C interface, which reduced the reflectivity of the multilayer film. Therefore, the insertion of a barrier layer carries the risk of introducing a new interface and is not applicable to all material combinations. It is necessary to develop and optimize the preparation process for different multilayer films.

[0005] Another effective method is nitridation. In 2010, T. Tsarfati et al. used a Kaufmann ion source to introduce nitrogen during magnetron sputtering of La / B₄C multilayers, significantly reducing interfacial diffusion of La / B₄C. Experimental results showed that post-nitridation of only the La layer achieved the best results. In 2013, IAMakhotkin et al. further proposed two different La nitridation methods. The first involves nitriding the La layer using an ion source, while the second involves reactive magnetron sputtering in a N₂+Ar atmosphere. Both methods improve the interfacial properties of the multilayer film, thereby enhancing its optical performance. However, the introduction of excessive N₂ during reactive sputtering can affect the optical properties of the multilayer film. In 2016, D.S. Kuznetsov et al. conducted a detailed analysis of the La nitridation process and found that excessive N₂ reacts with the scattering layer B, forming BN at the LaN / B interface, thereby reducing the reflectivity of the multilayer film. Summary of the Invention

[0006] The purpose of the present invention is to provide a Mo-based multilayer film and a preparation method and application thereof.

[0007] The first aspect of the present invention provides a multilayer film, wherein the multilayer film comprises a periodically stacked low-Z material layer / high-Z material layer, wherein the high-Z material is Mo, and the interface between the two adjacent periods of low-Z material layer and high-Z material layer further comprises Mo. x C 1-x Layer, where 0<x<1.

[0008] In one or more embodiments, the multilayer film has one or more of the following features:

[0009] The multilayer film comprises 1-300 periodic low-Z material layers / high-Z material layers;

[0010] The low Z material is B4C;

[0011] The total thickness of the low-Z material layer and the high-Z material layer in the same period is 1-20 nm;

[0012] The Mo x C 1-x The thickness of the layer is 0.2-0.5 nm;

[0013] A continuous adjacent layer of low Z material, a layer of Mo x C 1-x The total thickness of the layer and a layer of high-Z material is 1.2-20.5nm;

[0014] The Mo x C 1-xThe layers are formed by passing methane near a substrate during a process for preparing a multilayer film.

[0015] The second aspect of the present invention provides a method for preparing the multilayer film according to the first aspect of the present invention, the method comprising the step of introducing methane near a substrate during the preparation of the multilayer film.

[0016] In one or more embodiments, the flow ratio of the working gas to methane is ≥5:1; and / or the multilayer film is prepared by a magnetron sputtering coating method.

[0017] In one or more embodiments, the method has one or more of the following features:

[0018] The substrate is silicon;

[0019] The working gas is argon;

[0020] The flow ratio of the working gas to methane is (5-10):1;

[0021] In the magnetron sputtering coating method, the sputtering power density of the high-Z material target is 0.1-1.0 W / cm 2 ;

[0022] In the magnetron sputtering coating method, the sputtering power density of the low-Z material target is 1.0-2.0 W / cm 2 ;

[0023] The working pressure of the magnetron sputtering coating method is about 0.05-0.50 Pa;

[0024] In the magnetron sputtering coating method, the background vacuum degree is 2×10 -5 -10×10 -5 Pa;

[0025] The magnetron sputtering coating method adopts a planetary rotating target sputtering method.

[0026] The third aspect of the present invention provides a thin film device, which includes the multilayer film described in the first aspect of the present invention; preferably, the thin film device includes a substrate and the multilayer film described in the first aspect of the present invention arranged on the substrate; preferably, the substrate is silicon.

[0027] In one or more embodiments, the thin film device is a lens.

[0028] A fourth aspect of the present invention provides an optical system, comprising the thin film device according to the third aspect of the present invention.

[0029] A fifth aspect of the present invention provides a lithography machine, which includes the optical system described in the fourth aspect of the present invention.

[0030] A sixth aspect of the present invention provides a use selected from the following:

[0031] (1) Use of methane or a protective gas including methane in preparing the multilayer film according to the first aspect of the present invention;

[0032] (2)Mo x C 1-x Application in improving diffusion between high-Z material layers and low-Z material layers in multilayer films, inhibiting crystallization of high-Z material layers, and / or reducing roughness of interfaces between high-Z material layers and low-Z material layers; wherein 0<x<1;

[0033] (3) Application of the multilayer film described in the first aspect of the present invention in the preparation of thin film devices, optical systems and photolithography machines.

[0034] The present invention has the following beneficial effects:

[0035] The method of the present invention performs interface modification treatment on multilayer films whose high-Z material in the absorption layer is metal. The method of the present invention adds a trace amount of methane gas to the working gas argon of magnetron sputtering, and by mixing the metal element in the high-Z material in the absorption layer with the added methane gas, a protective barrier can be formed at the interface between the high-Z material and the low-Z material, which can prevent the diffusion of the metal element of the high-Z material and the low-Z material. The protective barrier layer formed by the reaction of methane gas and Mo can simultaneously inhibit the crystallization of the metal layer of the high-Z material in the absorption layer, and can reduce the roughness of the interface. The method of the present invention not only alleviates the diffusion problem of the high-Z material and the low-Z material, but also reduces the interface roughness of the high-Z material and the low-Z material, and effectively improves the interface quality and enhances the reflectivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a schematic diagram of experimental inflation in one or more embodiments.

[0037] Figure 2 It is the XRR spectrum of Mo / B4C series samples.

[0038] Figure 3 are the XRD patterns of all samples.

[0039] Figure 4 This is the TEM image of Mo / B4C multilayer film filled with 1 sccm methane and pure argon. DETAILED DESCRIPTION

[0040] To facilitate understanding of the features and effects of the present invention by those skilled in the art, the following provides a general description and definition of the terms and expressions used in the specification and claims. Unless otherwise indicated, all technical and scientific terms used herein have the ordinary meanings as understood by those skilled in the art regarding the present invention. In the event of conflict, the definitions in this specification shall prevail.

[0041] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.

[0042] Herein, “comprising,” “including,” “containing” and similar terms encompass the meanings of “consisting essentially of” and “consisting of,” for example, when “A comprises B and C” is disclosed herein, “A consists essentially of B and C” and “A consists of B and C” should be deemed to have been disclosed herein.

[0043] Throughout this document, all features, such as values, amounts, amounts, and concentrations, specified in numerical ranges or percentage ranges are provided for simplicity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to encompass and specifically disclose all possible subranges and individual values ​​within those ranges (including integers and fractions).

[0044] In this document, unless otherwise specified, percentage refers to mass percentage and ratio refers to mass ratio.

[0045] Herein, when describing embodiments or examples, it should be understood that they are not intended to limit the present invention to these embodiments or examples. On the contrary, all alternatives, modifications and equivalents of the methods and materials described herein are encompassed within the scope defined by the claims.

[0046] In this document, for the sake of brevity, not all possible combinations of the various technical features in each embodiment or example are described. Therefore, as long as there are no contradictions in the combination of these technical features, the various technical features in each embodiment or example can be combined in any way, and all possible combinations should be considered to be within the scope of this specification.

[0047] The present invention, by adding a trace amount of methane into the working gas, unexpectedly found that Mo is generated only on the Mo-on-B4C interface. x C 1-x The barrier layer not only alleviates the diffusion problem between high-Z materials and low-Z materials, but also reduces the interface roughness between high-Z materials and low-Z materials, which can effectively improve the interface quality and enhance the reflectivity.

[0048] In this paper, the barrier layer Mox C 1-x The x in the formula satisfies 0<x<1. x C 1-x The barrier layer represented by , x can be selected from any value between 0 < x < 1, and is generally not limited to a specific value. It is generally understood by those skilled in the art that Mo x C 1-x That is, it can clearly represent the mixed crystal phase of molybdenum carbide. If x is determined to be a specific value, then Mo x C 1-x It indicates a fixed phase, which usually cannot reduce the interface roughness.

[0049] The present invention provides a multilayer film, which comprises a periodically stacked low-Z material layer / high-Z material layer, wherein the high-Z material is Mo, and the interface between the two adjacent periods of low-Z material layer and high-Z material layer further comprises Mo. x C 1-x Layer, where 0<x<1.

[0050] Herein, one period of the multilayer film includes one low-Z material layer and one high-Z material layer. The multilayer film may include 1-300 periodic low-Z material layers / high-Z material layers, such as 5, 10, 20, 30, 50, 80, 100, 150, 200, preferably 10-50 or 5-10.

[0051] In some embodiments, the low Z material is B4C.

[0052] In some embodiments, the total thickness of the low-Z material layer and the high-Z material layer in the same period is 1-20 nm, for example, 10 nm, 12 nm, 13 nm, 14 nm, 15 nm.

[0053] Preferably, in the periodic low-Z material layer / high-Z material layer, the thickness of the low-Z material layer is 1-10 nm, for example, 2 nm, 3 nm, 5 nm, 8 nm, or 10 nm.

[0054] Preferably, in the periodic low-Z material layer / high-Z material layer, the thickness of the high-Z material layer is 1-10 nm, for example, 2 nm, 3 nm, 5 nm, 8 nm, or 10 nm.

[0055] In some embodiments, the Mo x C 1-x The thickness of the layer is 0.2-0.5 nm, for example 0.2 nm, 0.3 nm, 0.4 nm, 0.5 nm.

[0056] In some embodiments, a layer of low-Z material, a layer of Mo, and a xC 1-x The total thickness of the layer and the layer of high-Z material is 1.2-20.5 nm, for example 5 nm, 8 nm, 10 nm, 12 nm, 12.5 nm, 13 nm, 13.1 nm, 13.4 nm, 13.6 nm, 14 nm, 14.5 nm, 15 nm, 16 nm, 18 nm, 20 nm.

[0057] In some embodiments, the Mo x C 1-x The layers are formed by passing methane near a substrate during a process for preparing a multilayer film.

[0058] The present invention also provides a method for preparing the multilayer film of the present invention, the method comprising the step of preparing the multilayer film in a protective gas doped with methane.

[0059] In some embodiments, the method includes the step of passing methane near the substrate during the preparation of the multilayer film.

[0060] In some embodiments, the multilayer film is prepared by magnetron sputtering. In the art, a low-Z material layer is usually deposited first, followed by a high-Z material layer, and the deposition is repeated.

[0061] In some embodiments, the flow ratio of the protective gas to methane is ≥5:1, for example, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 12:1, 15:1, 18:1, 20:1, 25:1, 30:1, 35:1, 40:1, 50:1, preferably (5-50):1, (5-20):1 or (5-10):1.

[0062] In some embodiments, the substrate is silicon.

[0063] In some embodiments, the protective gas is argon.

[0064] In some embodiments, in the magnetron sputtering coating method, the sputtering power density of the high-Z material target is 0.1-1.0 W / cm 2 , for example 0.2W / cm 2 , 0.5W / cm 2 , 0.8W / cm 2 , 1.0W / cm 2 , preferably 0.1-0.5W / cm 2 or 0.5-1.0W / cm 2 .

[0065] In some embodiments, in the magnetron sputtering coating method, the sputtering power density of the low-Z material target is 1.0-2.0 W / cm 2, for example 1.2W / cm 2 , 1.3W / cm 2 , 1.5W / cm 2 , 1.8W / cm 2 , 2.0W / cm 2 , preferably 1.0-1.5W / cm 2 or 1.5-2.0W / cm 2 .

[0066] In some embodiments, the working pressure of the magnetron sputtering coating method is about 0.05-0.50 Pa, such as 0.1 Pa, 0.15 Pa, 0.2 Pa, 0.3 Pa, 0.4 Pa, preferably 0.15-0.4 Pa, 0.15-0.3 Pa, 0.15-0.2 Pa or 0.1-0.15 Pa.

[0067] In some embodiments, in the magnetron sputtering coating method, the background vacuum degree is 2×10 -5 -10×10 - 5 Pa, for example 2×10 -5 Pa, 3×10 -5 Pa, 4×10 -5 Pa, 5×10 -5 Pa, 6.5×10 -5 Pa, 7×10 -5 Pa, 9×10 -5 Pa, preferably 2×10 -5 -6.5×10 -5 Pa, 6.5×10 -5 -10×10 -5 Pa or 6×10 -5 -7×10 -5 Pa.

[0068] In some embodiments, the magnetron sputtering coating method adopts a planetary rotating glancing target sputtering method.

[0069] Figure 1 The following is a schematic diagram of an exemplary experimental inflation. Figure 1 As shown, Mo target and B4C target are alternately deposited onto the substrate in the presence of working gas. In some embodiments, methane gas is introduced near the substrate surface only when the Mo target is exposed to the substrate.

[0070] The present invention also provides a thin film device comprising the multilayer film of the present invention. In some embodiments, the thin film device comprises a substrate and the multilayer film of the present invention disposed on the substrate. Preferably, the substrate is silicon. In some embodiments, the thin film device is a lens, preferably an optical lens. In some embodiments, the multilayer film is as described in any embodiment herein.

[0071] The present invention provides an optical system, which includes the thin film device of the present invention.

[0072] The present invention provides a photolithography machine, which comprises the optical system of the present invention.

[0073] The present invention also provides an application selected from the following:

[0074] (1) Use of methane or a protective gas including methane in preparing the multilayer film of the present invention;

[0075] (2)Mo x C 1-x Application in improving diffusion between high-Z material layers and low-Z material layers in multilayer films, inhibiting crystallization of high-Z material layers, and / or reducing roughness of interfaces between high-Z material layers and low-Z material layers; wherein 0<x<1;

[0076] (3) Use of the multilayer film according to claim 1 or 2 in the preparation of thin film devices, optical systems and photolithography machines.

[0077] In some embodiments, the multilayer film, high-Z material layer, low-Z material layer, thin film device, optical system, and photolithography machine are as described in any embodiment herein.

[0078] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are intended to illustrate the present invention only and are not intended to limit the scope of the invention. The experimental methods in the following examples, for which specific conditions are not specified, are generally based on conventional conditions or the conditions recommended by the manufacturer. Unless otherwise stated, percentages and parts are calculated by weight.

[0079] Period thickness, thickness of low-Z material layer, thickness of high-Z material layer and Mo generated in the interface between adjacent Mo and B4C x C 1-x The thickness of the barrier layer can be measured by XRR and TEM spectra.

[0080] In this paper, transmission electron microscopy and EDS spectroscopy were used to confirm that the structure of the barrier layer is Mo x C 1-x , where 0<x<1.

[0081] Herein, the periodic thickness of a multilayer film refers to the total thickness of a continuously adjacent layer of a low-Z material, a barrier layer, and a high-Z material layer.

[0082] In this paper, B4C-on-Mo refers to B4C on the Mo surface.

[0083] In this paper, Mo-on-B4C refers to Mo on the surface of B4C.

[0084] Example 1 (Mo / B4C multilayer film)

[0085] In this embodiment, a Sub Si / [Mo / B4C]^10 multilayer film sample S1-1 is prepared. An ultra-smooth substrate Sub Si is placed in a vacuum coating machine. In an atmosphere of argon gas of 10 sccm and methane gas of 1 sccm, high-Z material Mo and low-Z material B4C are used as targets to alternately grow Mo / B4C multilayer films on the surface of the ultra-smooth substrate by magnetron sputtering. Each cycle is a layer of molybdenum plus a layer of boron carbide, which is called a cycle. The entire sample is cycled ten times, which is 10 cycles. The conditions for magnetron sputtering are: the molybdenum sputtering power density is 0.5W / cm 2 , the boron carbide sputtering power density is 1.5W / cm 2 The sputtering working pressure is about 0.15Pa, and the background vacuum is 6.5×10 -5 Pa, using planetary rotating target sputtering. The periodic thickness is 13.40nm. Mo generated at the interface between adjacent Mo and B4C x C 1-x The thickness of the barrier layer is 0.20 nm.

[0086] Example 2 (Mo / B4C multilayer film)

[0087] In this embodiment, a Sub Si / [Mo / B4C]^10 multilayer film sample S1-2 is prepared. An ultra-smooth substrate Sub Si is placed in a vacuum coating machine. In an atmosphere of argon gas of 10 sccm and methane gas of 2 sccm, high-Z material Mo and low-Z material B4C are used as targets to alternately grow Mo / B4C multilayer films on the surface of the ultra-smooth substrate by magnetron sputtering. Each cycle is a layer of molybdenum plus a layer of boron carbide, which is called a cycle. The entire sample is cycled ten times, which is 10 cycles. The conditions for magnetron sputtering are: the molybdenum sputtering power density is 0.5W / cm 2 , the boron carbide sputtering power density is 1.5W / cm 2 The sputtering working pressure is about 0.15Pa, and the background vacuum is 6.5×10 -5 Pa, using planetary rotating target sputtering. The periodic thickness is 13.60nm. Mo generated at the interface between adjacent Mo and B4C x C1-x The thickness of the barrier layer is 0.50 nm.

[0088] Comparative Example 1 (Mo / B4C multilayer film)

[0089] In this comparative example, a Sub Si / [Mo / B4C]^10 multilayer film sample S1 was prepared. An ultra-smooth Sub Si substrate was placed in a vacuum coating machine. In an argon atmosphere of 10 sccm, high-Z material Mo and low-Z material B4C were used as targets. Mo / B4C multilayer films were grown alternately on the surface of the ultra-smooth substrate by magnetron sputtering. The total number of cycles was 10. The magnetron sputtering conditions were: the molybdenum sputtering power density was 0.5 W / cm 2 , the boron carbide sputtering power density is 1.5W / cm 2 The sputtering working pressure is about 0.15Pa, and the background vacuum is 6.5×10 -5 Pa, using planetary rotating target sputtering method. The periodic thickness is 13.50nm.

[0090] Test Example 1

[0091] The samples of all embodiments and comparative examples were subjected to X-ray reflectometry (XRR) tests using an Empyrean multifunctional X-ray diffractometer (Cu-α, 0.154 nm) under grazing incidence conditions and based on a five-axis sample stage. The test results are shown in FIG. Figure 2 and Figure 3 As shown. XRR is an effective method to characterize the periodic structure and thickness of multilayer films. It mainly determines the interface quality and film thickness of the sample based on the number and position of Bragg peaks, combined with the modified Bragg equation for fitting analysis. The better the interface of the prepared multilayer film, the more Bragg peaks there are. Figure 2 From the XRR spectra of the Mo / B4C multilayer films, it can be seen that the Mo / B4C multilayer films S1-1 and S1-2 filled with methane gas have more XRR Bragg peaks than the Mo / B4C multilayer film S1 which is not filled with methane gas.

[0092] Based on the Nevot-Croce criterion, the interface roughness or width was incorporated into the model using an attenuation factor. The data were fitted and statistically analyzed using the Levenberg-Marquart least-squares fitting algorithm. The results are shown in Table 1 below. Combined with the fitting results in Table 1, it can be seen that the roughness of multilayer films produced with methane as the working gas is lower than that without methane filling, and the roughness is even lower when the argon:methane flow ratio is between 5 and 10:1.

[0093]

[0094] Test Example 2

[0095] The X-ray diffraction (XRD) spectrum of all the samples of the embodiments and comparative examples was tested using an Empyrean multifunctional X-ray diffractometer (Cu-α, 0.154 nm) based on the Theta-2Theta scanning mode. The test results are shown in FIG. Figure 4 As shown. XRD is an effective method for material crystallization testing, which mainly matches the peak shape and angle position corresponding to the diffraction peak with the database, or the type of crystalline material and crystal quality corresponding to the diffraction peak. Figure 3 As can be seen in the figure, the Mo / B4C multilayer sample S1, which was not filled with methane, exhibits three distinct diffraction peaks near 2Theta of 40°, 58°, and 73°, corresponding to the Mo(110), Mo(200), and Mo(211) crystalline phases, respectively, indicating distinct Mo layer crystallization. The XRD spectrum of the multilayer sample filled with trace amounts of methane gas only exhibits a broad, bun-shaped peak near 40°, indicating a nearly amorphous state.

[0096] Test Example 3

[0097] The interface structure of S1 and S1-1 multilayer films was characterized by a field emission transmission electron microscope (TEM) of model JEM-2100F. The TEM images of Mo / B4C multilayer films in the state of 1 sccm methane and pure argon are shown in Figure 2. Figure 4 As shown. The TEM spectrum can more intuitively show the smoothness of the interface, the interface diffusion and mixing, and the crystallization state. It can be clearly seen that the interface of sample S1-1 prepared after filling with 1sccm of methane is smoother than the interface of sample S1 without methane filling, indicating that the interface roughness and interface diffusion are significantly reduced after filling with 1sccm of methane. From the high-resolution TEM, it can also be seen that the pattern of S1 without methane filling shows a clear and neat crystal lattice arrangement in the Mo layer, while the S1-1 samples after filling with methane are all disordered amorphous arrangements, that is, filling with 1sccm of methane has played a role in inhibiting Mo crystallization.

[0098] In summary, in the preparation of Mo-based multilayer films, a small amount of methane gas is added to the working gas argon, and the working gas Ar is passed to the surface of the Mo target, and methane is passed to the surface of the substrate to modify the Mo. The small amount of methane reacts with Mo to form an ultra-thin Mo on the surface of Mo-on-B4C. x C 1-x The (0<x<1) barrier layer can effectively block the diffusion of Mo and B4C, solving the interface diffusion problem. At the same time, methane reacts with part of Mo to generate Mo x C 1-xThe (0<x<1) barrier layer effectively inhibits Mo crystallization, resolving the problem of high interface roughness caused by Mo crystallization. In addition to significantly improving the multilayer film interface, methane does not react with the low-Z material B4C to form other compounds. Therefore, incorporating trace amounts of methane into the working gas can effectively improve the reflectivity of the multilayer film. This invention, using argon and methane as working gases to prepare multilayer films, is an innovative method for preparing multilayer films in which the high-Z material of the absorption layer is metal.

Claims

1. A multilayer film, characterized in that The multilayer film comprises a periodically stacked low-Z material layer / high-Z material layer, wherein the high-Z material is Mo, and the interface between the two adjacent periods of low-Z material layer and high-Z material layer further comprises Mo. x C 1-x Layer, where 0<x<1.

2. The multilayer film according to claim 1, wherein The multilayer film has one or more of the following characteristics: The multilayer film comprises 1-300 periodic low-Z material layers / high-Z material layers; The low Z material is B4C; The total thickness of the low-Z material layer and the high-Z material layer in the same period is 1-20 nm; The Mo x C 1-x The thickness of the layer is 0.2-0.5 nm; A continuous adjacent layer of low Z material, a layer of Mo x C 1-x The total thickness of the layer and a layer of high-Z material is 1.2-20.5nm; The Mo x C 1-x The layers are formed by passing methane near a substrate during a process for preparing a multilayer film.

3. A method for preparing the multilayer film according to claim 1 or 2, characterized in that: The method comprises the steps of: introducing methane near a substrate during the preparation of the multilayer film.

4. The method according to claim 3, wherein The flow ratio of the working gas to methane is ≥5:1; and / or, the multilayer film is prepared by a magnetron sputtering coating method.

5. The method according to claim 4, wherein The method has one or more of the following characteristics: The substrate is silicon; The working gas is argon; The flow ratio of the working gas to methane is (5-10):1; In the magnetron sputtering coating method, the sputtering power density of the high-Z material target is 0.1-1.0 W / cm 2 ; In the magnetron sputtering coating method, the sputtering power density of the low-Z material target is 1.0-2.0 W / cm 2 ; The working pressure of the magnetron sputtering coating method is about 0.05-0.50 Pa; In the magnetron sputtering coating method, the background vacuum degree is 2×10 -5 -10×10 -5 Pa; The magnetron sputtering coating method adopts a planetary rotating target sputtering method.

6. A thin film device, characterized in that: The thin film device comprises the multilayer film according to claim 1 or 2; preferably, the thin film device comprises a substrate and the multilayer film according to claim 1 or 2 disposed on the substrate; preferably, the substrate is silicon.

7. The thin film device according to claim 6, wherein: The thin film device is a lens.

8. An optical system, characterized in that The optical system includes the thin film device according to claim 6 or 7.

9. A photolithography machine, characterized in that: The lithography machine includes the optical system according to claim 8.

10. Select from the following applications: (1) Use of methane or a protective gas including methane in the preparation of the multilayer film according to claim 1 or 2; (2)Mo x C 1-x Application in improving the diffusion between the high-Z material layer and the low-Z material layer in the multilayer film, inhibiting the crystallization of the high-Z material layer and / or reducing the roughness of the interface between the high-Z material layer and the low-Z material layer; wherein, 0＜x＜1； (3) Use of the multilayer film according to claim 1 or 2 in the preparation of thin film devices, optical systems and photolithography machines.

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