Method and device for preparing multilayer film through reactive magnetron sputtering

Abstract

The invention belongs to the technical field of short-wavelength optical devices, and particularly relates to a method and device for preparing a multilayer film through reactive magnetron sputtering. The method comprises the following steps: (1) depositing an X layer on a substrate in the atmosphere of working gas; (2) depositing a Y layer on the substrate on which the X layer is deposited in the atmosphere of working gas; (3) depositing a Z layer on the substrate on which the X layer and the Y layer are deposited in the range of the working gas and the reaction gas; and repeating the steps (1) to (3) for a plurality of cycles to prepare the multilayer film. The X layer is B4C, Si or Al; the Y layer is La, Mo or Ti; the Z layer is LaN, MoN or TiN; the reaction gas is nitrogen.

Description

Technical Field

[0001] This invention belongs to the field of short-wavelength optical device technology, specifically relating to a method and apparatus for preparing multilayer films by reactive magnetron sputtering. Background Technology

[0002] In the short-wavelength extreme ultraviolet (EUV) field, La / B4C-based multilayer materials show potential applications in free-electron lasers and photolithography. However, there is a significant discrepancy between theoretical predictions and experimental measurements regarding the reflectivity of La / B4C multilayers. This is mainly due to the diffusion and compound formation at the interfaces within the multilayer, leading to a reduction in interfacial optical contrast and thus significantly decreasing the reflectivity of short-wavelength mirrors. In multilayers, barrier layers and interface passivation layers are generally used to mitigate interfacial diffusion. Lanthanum nitride barrier layers, with their high formation enthalpy, effectively block the interdiffusion phenomenon caused by the reaction between B and La atoms at the interface. Most high-reflectivity La / B4C-based multilayers are prepared using N2 reactive sputtering of a La target to produce LaN. However, during magnetron sputtering of La / B4C multilayers, BN has a lower formation enthalpy than LaN. Therefore, N2 preferentially reacts with the B4C target during sputtering. This results in a large amount of BN in the B4C layer of the La / B4C multilayer, which reduces interfacial optical contrast. Furthermore, literature review shows that the effect of BN at the interface on reflectivity is far greater than that of the interface compound LaB6 at the same thickness. In addition, to achieve the highest theoretical reflectivity of La / B4C-based multilayer films at a normal incident angle, the number of multilayer film cycles needs to reach 250 or more.

[0003] Therefore, in order to achieve automatically stable sputtering conditions in high-cycle multilayer film deposition and deposit only the LaN layer while avoiding BN deposition, there is a need in the art for a method to avoid the reaction between N2 and the B4C target during hundreds of deposition cycles, and for N2 to react with La only during sputtering, thereby further improving the reflectivity of the multilayer film. Summary of the Invention

[0004] The purpose of this invention is to provide a method and apparatus for preparing multilayer films by reactive magnetron sputtering.

[0005] A first aspect of the present invention provides a method for preparing a multilayer film, the method comprising the steps of:

[0006] (1) Deposit layer X on substrate in working gas atmosphere;

[0007] (2) In the atmosphere of the working gas, deposit layer Y on the substrate where layer X has been deposited;

[0008] (3) Within the range of working gas and reactant gas, deposit layer Z on the substrate on which layers X and Y are deposited;

[0009] Repeat steps (1) to (3) multiple times to obtain the multilayer film;

[0010] During one cycle from step (1) to step (3), the reaction gas is introduced between the completion of the deposition in step (2) and the start of the deposition in step (3);

[0011] Stop the flow of reaction gas before the deposition in step (3) is completely completed and before the deposition in the next cycle step (1) begins;

[0012] The flow patterns of the reactant gases are selected from rectangular, sinusoidal, and linear.

[0013] The X layer is B4C, Si, or Al;

[0014] The Y layer is made of La, Mo, or Ti;

[0015] The Z layer is LaN, MoN, or TiN;

[0016] The reacting gas is nitrogen.

[0017] A second aspect of the present invention provides a multilayer film arranged in a periodic stack, each period including X / Y / Z layers, wherein the X layer is selected from B4C, Si and Al, the Y layer is selected from La, Mo and Ti, and the Z layer is selected from LaN, MoN and TiN.

[0018] A third aspect of the present invention provides an apparatus for preparing multilayer films by reactive magnetron sputtering, the apparatus comprising a sample disk on which a substrate is disposed, two or more targets, a rotation system for rotating the sample disk to pass sequentially through each target for magnetron sputtering, a working gas filling system, a reactive gas filling system, and a monitoring device for monitoring the rotation angle of the sample disk.

[0019] The fourth aspect of the present invention provides the application of the method described in the first aspect of the present invention or the apparatus described in the third aspect of the present invention in the preparation of multilayer films with high optical contrast and high reflectivity.

[0020] The present invention has the following beneficial effects:

[0021] (1) Compared with the traditional reactive sputtering process where the reactive gas is always on, the method of the present invention utilizes an automatic control system for the reactive gas switch to prepare high-period multilayer films containing only the required reactive sputtering material layer more flexibly and conveniently, and can selectively avoid the deposition of materials that are detrimental to the film performance.

[0022] (2) The method of the present invention can adjust the flow rate of the reaction gas and the flow rate increase mode at will, and can realize flexible control of the composition and film thickness of the reactive sputtering material, and even realize the deposition of a gradient composition film with high reproducibility.

[0023] (3) Compared with conventional reactive sputtering devices, the device of the present invention can switch the reactive gas at any rotation position, thereby realizing reactive sputtering deposition of any material in a multilayer film system structure, thereby obtaining a combination of any multilayer film system structure.

[0024] (4) The preparation process of the present invention is simple and compatible with reaction sputtering processes of any gas, making it suitable for large-scale industrial production. Attached Figure Description

[0025] Figure 1 This is a schematic diagram illustrating the control of the N2 switch via the sample disk angle position as described in one or more embodiments of the present invention. When the sample disk rotates to between 160-200° (the opening position can be selected from any angle within this range), the reaction gas valve switch automatic control system opens N2 and performs reactive sputtering deposition of a lanthanum nitride layer. When the sample disk rotates to between 250-290°, N2 is turned off.

[0026] Figure 2 This illustrates the relationship between N2 flow rate and angle when the N2 valve is opened in Examples 1-3. By using different methods to increase the N2 flow rate, the concentration of N element in the LaN layer can be varied, thereby depositing LaN films with different concentration gradients.

[0027] Figure 3 This comparison examines the theoretically calculated reflectance of [B4N4C / La / LaN]^250 deposited under normally-on N2 conditions (Comparative Example 1) and [B4C / La / LaN]^250 deposited under periodically-switched N2 conditions (Example 1) during magnetron sputtering of multilayer films. The reflectance of [B4N4C / La / LaN]^250 is 58.7%, a decrease of 16.9% compared to the reflectance of [B4C / La / LaN]^250 (75.6%). This is primarily due to the reactive sputtering of N2 with the B4C target, resulting in a large amount of BN in the B4C layer, which reduces the interfacial optical contrast of the multilayer film. Figure 3 The study also includes the reflectance curve of the multilayer film prepared in Comparative Example 2.

[0028] Figure 4 These are the reflectance curves of the multilayer films prepared in Example 5 and Comparative Examples 3-4.

[0029] Figure 5 These are the reflectance curves of the multilayer films prepared in Example 6 and Comparative Examples 5-6. Detailed Implementation

[0030] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0031] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0032] In this document, the terms “contains,” “includes,” “containing,” and similar terms encompass the meanings of “basically composed of” and “composed of.” For example, when this document discloses “A contains B and C,” “A is basically composed of B and C” and “A is composed of B and C” should be considered as having been disclosed in this document.

[0033] In this document, all features defined in the form of numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0034] Unless otherwise specified, percentages refer to mass percentages and proportions refer to mass ratios in this article.

[0035] In this document, when describing embodiments or examples, it should be understood that it is not intended to limit the invention to those embodiments or examples. Rather, all alternatives, modifications, and equivalents of the methods and materials described herein are covered within the scope defined by the claims.

[0036] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0037] To effectively solve the above problems, this invention utilizes an automatic control system for gas valve switching (mass flow meter, position sensor, programmable logic controller) to regulate the opening and closing of the reactive gas during the deposition of different materials. The purpose is to use a pulsed DC sputtering power supply to reactively sputter and deposit the target film layer required in the preparation of multilayer films while avoiding the deposition of non-target film layers.

[0038] In this paper, the opening and closing of the N2 valve for the reactive gas is controlled based on the rotation angle of the sample disk. The trajectory of one rotation of the sample disk forms a circle. At the starting position of the rotation, the sample disk forms a ray with the center of the circle. At any position during the rotation, the sample disk forms another ray with the center of the circle. The angle between the two rays is the rotation angle of the sample disk.

[0039] This invention provides a method for preparing a multilayer film, the method comprising the steps of:

[0040] (1) Deposit layer X on substrate in working gas atmosphere;

[0041] (2) In the atmosphere of the working gas, deposit layer Y on the substrate where layer X has been deposited;

[0042] (3) Within the range of working gas and reactant gas, deposit layer Z on the substrate on which layers X and Y are deposited;

[0043] Repeat steps (1) to (3) multiple times to obtain the multilayer film;

[0044] The X layer is B4C, Si, or Al;

[0045] The Y layer is made of La, Mo, or Ti;

[0046] The Z layer is LaN, MoN, or TiN;

[0047] The reacting gas is nitrogen.

[0048] In some implementations, the substrate is Si.

[0049] In some implementations, the X layer is B4C, the Y layer is La, and the Z layer is LaN; or, the X layer is Si, the Y layer is Mo, and the Z layer is MoN; or the X layer is Al, the Y layer is Ti, and the Z layer is TiN.

[0050] In some embodiments, the multilayer film is B4C / La / LaN, Si / Mo / MoN, or Al / Ti / TiN.

[0051] In some implementations, the working gas is argon.

[0052] In some implementations, step (1) includes: depositing an X layer using a first target material selected from B4C, Si, and Al.

[0053] In some implementations, step (2) includes: depositing a Y layer using a second target material selected from La, Mo and Ti.

[0054] In some implementations, step (3) includes depositing a Z layer using a third target material selected from La, Mo, and Ti.

[0055] In some implementations, the first target is B4C, the second target is La, and the third target is La; or the first target is Si, the second target is Mo, and the third target is Mo; or the first target is Al, the second target is Ti, and the third target is Ti.

[0056] In some implementations, steps (1) to (3) are repeated for 25-250 cycles, such as 25 cycles, 30 cycles, 40 cycles, 50 cycles, 60 cycles, 70 cycles, 100 cycles, 150 cycles, 200 cycles, or 250 cycles, preferably 40-250 cycles, 40-50 cycles, or 200-250 cycles.

[0057] Preferably, during one cycle from step (1) to step (3), the reaction gas is introduced between the completion of deposition in step (2) and the start of deposition in step (3).

[0058] Preferably, the flow of reaction gas is stopped before the deposition in the next cycle step (1) begins, after the deposition in step (3) is completely completed.

[0059] In this article, "deposition is completely completed" refers to the earliest time when the sample disk is completely separated from the specific target material, and "the sample disk is completely separated from the specific target material" means that when viewed in a direction perpendicular to the plane of the target material and the sample disk, the target material and the sample disk do not overlap.

[0060] In this article, "before deposition begins" refers to the earliest time when the sample disk begins to contact the specific target material, and "the sample disk begins to contact the specific target material" means that when viewed in a direction perpendicular to the plane of the target material and the sample disk, the target material and the sample disk overlap.

[0061] In actual preparation, the content of the reactant gas in the system is 0 the instant the flow of reactant gas is stopped.

[0062] Preferably, the flow pattern of the reactant gas can be rectangular, sinusoidal, or linear. Different flow patterns primarily affect the composition of the reactive sputtered film, thus forming a compositional gradient film and altering the stress and optical constants of the film. For example, when the reactant gas is nitrogen, different flow patterns can be used to prepare multilayer films with different nitrogen contents, ultimately resulting in multilayer films with different physical properties.

[0063] Preferably, the flow rate of the reactant gas is 1-20 sccm, for example 2 sccm, 4 sccm, 5 sccm, 8 sccm, 10 sccm, 15 sccm, 18 sccm, and more preferably 5-10 sccm or 5-15 sccm.

[0064] In some implementations, in step (1), the deposition is pulsed DC magnetron sputtering.

[0065] In some implementations, in step (1), the background vacuum before magnetron sputtering is ≤1×10⁻⁶. -5 Pa.

[0066] In some implementations, in step (1), the sputtering method is target grazing.

[0067] In some implementations, in step (1), the purity of the first target material is ≥ 99.5%.

[0068] In some implementations, in step (1), the working pressure is 0.1-0.3 Pa, for example 0.15 Pa, 0.2 Pa, 0.25 Pa, 0.3 Pa, preferably 0.1-0.15 Pa, 0.15-0.3 Pa or 0.15-0.2 Pa.

[0069] In some implementations, in step (1), the sputtering power is 400-650 W, for example 400 W, 450 W, 500 W, 550 W, 600 W, preferably 450-500 W, 500-600 W, 450-550 W.

[0070] In some implementations, in step (2), the deposition is pulsed DC magnetron sputtering.

[0071] In some implementations, in step (2), the background vacuum before magnetron sputtering is ≤1×10⁻⁶. -5 Pa.

[0072] In some implementations, in step (2), the sputtering method is target grazing.

[0073] In some implementations, in step (2), the purity of the second target material is ≥ 99.5%.

[0074] In some implementations, in step (2), the working pressure is 0.1-0.3 Pa, for example 0.15 Pa, 0.2 Pa, 0.25 Pa, 0.3 Pa, preferably 0.1-0.15 Pa, 0.15-0.3 Pa or 0.15-0.2 Pa.

[0075] In some implementations, in step (2), the sputtering power is 50-100 W, for example 50 W, 60 W, 70 W, 80 W, 90 W, 100 W, preferably 50-80 W, 80-100 W or 70-90 W.

[0076] In some implementations, in step (3), the deposition is performed by pulsed DC magnetron sputtering.

[0077] In some implementations, in step (3), the sputtering method is target grazing.

[0078] In some implementations, in step (3), the purity of the third target material is ≥ 99.5%.

[0079] In some implementations, in step (3), the working pressure is 0.1-0.3 Pa, for example 0.15 Pa, 0.19 Pa, 0.2 Pa, 0.25 Pa, 0.3 Pa, preferably 0.1-0.19 Pa, 0.19-0.3 Pa or 0.15-0.2 Pa.

[0080] In some implementations, in step (3), the sputtering power is 100-150 W, for example 100 W, 110 W, 120 W, 130 W, 140 W, 150 W, preferably 100-120 W, 120-150 W or 110-130 W.

[0081] Preferably, the preparation method of the present invention is carried out using the apparatus described herein.

[0082] In some implementation schemes, the use of Figure 1 The apparatus shown implements the preparation method of the present invention, the method comprising the steps of:

[0083] (1) When the sample disk rotates 0-90°, layer X is deposited on the substrate;

[0084] (2) When the sample disk rotates 90-180°, a Y layer is deposited on top of the X layer;

[0085] (3) When the sample tray rotates to 180°, the logic controller detects the angle signal of the position sensor and controls the gas valve to open in a rectangular flow rate increase manner, wherein the maximum gas flow rate is 10 sccm;

[0086] (4) When the sample disk rotates 180-270°, the Z layer is deposited by reaction sputtering on the basis of the Y layer;

[0087] (4) When the sample is rotated to 360°, the preparation of one cycle of thin film is completed, and the above steps are repeated in sequence to prepare the X layer, Y layer and Z layer, and finally a high-cycle X / Y / Z multilayer film is obtained.

[0088] The definitions of the substrate, X layer, Y layer, and Z layer are as described in any embodiment of this document.

[0089] Multilayer films, optical equipment, optical components

[0090] The present invention provides a multilayer film arranged in a periodic stack, each period including X / Y / Z layers, wherein the X layer is selected from B4C, Si and Al, the Y layer is selected from La, Mo and Ti, and the Z layer is selected from LaN, MoN and TiN.

[0091] In some embodiments, each cycle comprises B4C / La / LaN. In some embodiments, each cycle comprises Si / Mo / MoN. In some embodiments, each cycle comprises Al / Ti / TiN.

[0092] In some embodiments, the multilayer film comprises 25-250 cycles of X / Y / Z layers.

[0093] In some embodiments, the thickness of the X layer can be 1.5-6.5 nm, for example 1.5 nm, 1.75 nm, 2 nm, 2.2 nm, 2.5 nm, 2.8 nm, 3 nm, 3.3 nm, 3.5 nm, 3.8 nm, 4 nm, 4.1 nm, 4.2 nm, 4.5 nm, 4.8 nm, 5 nm, 5.5 nm, 6 nm, 6.2 nm, 6.4 nm, 6.5 nm, preferably 1.7-6.5 nm.

[0094] In some implementations, the thickness of the Y layer can be 1-2.5 nm, such as 1.15 nm, 1.2 nm, 1.5 nm, 2 nm, 2.2 nm, 2.3 nm, 2.5 nm, preferably 1.1-2.3 nm.

[0095] In some implementations, the thickness of the Z layer can be 0.1-1 nm, such as 0.2 nm, 0.4 nm, 0.5 nm, 0.6 nm, 0.8 nm, or 0.9 nm, preferably 0.3-0.8 nm or 0.5-0.8 nm.

[0096] In some implementations, the total thickness of the multilayer film can be 3.4-9.5 nm, for example 3.4 nm, 3.5 nm, 3.8 nm, 4 nm, 4.2 nm, 4.5 nm, 4.8 nm, 5 nm, 5.5 nm, 6 nm, 6.5 nm, 6.8 nm, 6.9 nm, 7 nm, 7.5 nm, 8 nm, 8.5 nm, and 9 nm.

[0097] In some embodiments, the multilayer film of the present invention is prepared using the preparation method of the present invention.

[0098] The present invention also provides an optical device comprising the multilayer film of the present invention. In some embodiments, the optical device is a lens.

[0099] The present invention also provides an optical component including the optical device of the present invention.

[0100] Device

[0101] This invention provides an apparatus for preparing multilayer films by reactive magnetron sputtering. The apparatus includes a sample disk with a substrate, two or more targets, a rotation system for rotating the sample disk to pass sequentially through each target for magnetron sputtering, a working gas filling system, a reactive gas filling system, and a monitoring device for monitoring the rotation angle of the sample disk.

[0102] The device may include 3, 4, 5, or 6 targets. The targets are distributed circumferentially along the rotational trajectory of the sample disk; preferably, any axis of symmetry between any two targets passes through the center of this circle.

[0103] In some embodiments, the device includes three targets; preferably, the three targets are arranged counterclockwise as a first target, a second target, and a third target. In some embodiments, the device includes four targets; preferably, the four targets are arranged counterclockwise as a first target, a second target, a third target, and a fourth target. In actual operation, when the device includes four targets, the sample disk rotates counterclockwise, passing through the first target, the second target, the third target, and the fourth target in sequence.

[0104] In some embodiments, the target is provided with the same or different target materials, or the target is an empty target without any target material. Using an empty target can improve the sputtering stability of the device during operation. In some embodiments, the device includes four targets: the first, second, and third targets are provided with the same or different target materials, and the fourth target is an empty target. In actual use, the sample disk passes sequentially through the first, second, third, and fourth targets, and the substrate sequentially undergoes magnetron sputtering with the target materials on the first, second, and third targets.

[0105] In some embodiments, the working gas filling system is used to fill the surface of the respective targets with working gas; preferably, the working gas filling system is an argon filling system. The working gas filling system includes valves for controlling the filling of the working gas.

[0106] In some embodiments, the reactive gas filling system is used to fill the surface of the respective targets with reactive gas; preferably, the reactive gas filling system is a nitrogen filling system. The reactive gas filling system includes valves for controlling the filling of the reactive gas.

[0107] In some implementations, the monitoring device for monitoring the rotation angle of the sample pan is connected to the reaction gas filling system via an electrical signal. The reaction gas filling system can automatically control the filling or stopping of reaction gas at specific rotation angles based on the electrical signal indicating the rotation angle of the sample pan.

[0108] like Figure 1 As shown, this invention provides an apparatus comprising four targets. The four targets are evenly and symmetrically distributed on the circumference formed by the rotation of the sample disk. In this apparatus, the targets are arranged counterclockwise as follows: a first target, a second target, a third target, and a fourth target. The substrate on the sample disk is Si, the target material on the first target is B4C, the target material on the second target is La, the target material on the third target is La, and the fourth target is an empty target. In actual operation, the initial rotation position (0°) of the sample disk is located on the axis of symmetry between the first and fourth targets. The sample disk rotates counterclockwise one revolution, passing through the first, second, third, and fourth targets in sequence, performing sputtering of the B4C target, sputtering of the La target, and reactive sputtering of the La target in a nitrogen atmosphere in sequence. When the sample disk rotates to between 160-200° (e.g., 180°), the valve of the reactive gas charging system is opened to introduce nitrogen gas. When the sample disk rotates to between 250-290° (e.g., 270°), the valve of the reactive gas charging system is closed to stop the introduction of nitrogen gas.

[0109] In some embodiments, the device includes four targets: the first target is made of Si, the second target is made of Mo, the third target is made of Mo, and the fourth target is an empty target.

[0110] In some embodiments, the device includes four targets: the first target has Al as the target material, the second target has Ti as the target material, the third target has Ti as the target material, and the fourth target is an empty target.

[0111] application

[0112] This invention provides the application of the preparation method or apparatus of this invention in the preparation of multilayer films with high optical contrast and high reflectivity.

[0113] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. Percentages and parts are by weight unless otherwise stated.

[0114] Example 1

[0115] The method for preparing Sub / [B4C / La / LaN]^250 multilayer films includes the following steps:

[0116] Background vacuum ≤1×10 -5At Pa, the sample disk with the silicon substrate is reset to the 0° position. The substrate is a silicon wafer with a roughness of 0.2 nm. During the fabrication of the multilayer film, the sample disk is kept rotating uniformly. The rotation speed is determined by the specific thickness of the film layer (X / Y / Z layer) to be deposited. The sample disk is as follows: Figure 1 As shown, target 4 is an empty target, target 1 is B4C, and targets 2 and 3 are La.

[0117] When the sample disk rotates 0-90°, a B4C layer is deposited on the Si substrate using pulsed DC sputtering. The parameters include: glide target deposition method, target purity ≥99.5%, argon working gas, preferably 0.15 Pa working pressure, and preferably 500 W sputtering power.

[0118] When the sample disk rotates 90-180°, a La layer is deposited on the B4C layer using pulsed DC sputtering. The parameters include: the coating method is grazing target, the target purity is ≥99.5%, the working gas is argon, the working pressure is preferably 0.15 Pa, and the sputtering power is preferably 80W.

[0119] When the sample tray rotates 180°, the controller detects the angle signal from the position sensor and controls the N2 valve to release gas in a rectangular opening manner. The nitrogen release method is as follows: Figure 2 As shown in "N2-rectangle".

[0120] When the sample disk rotates 180-270°, the N2 flow rate is maintained at 5 sccm. The LaN layer is prepared on the La layer by pulsed DC sputtering. The parameters include: the coating method is grazing target, the target purity is ≥99.5%, the working gas is a nitrogen-argon mixture, the working pressure is preferably 0.19 Pa, and the sputtering power is preferably 120 W.

[0121] When the sample rotates to 360°, the preparation of one cycle of the thin film is completed. Argon gas is continuously released at a constant flow rate throughout one rotation of the sample disk. This process is repeated 250 times to obtain 250 cycles of B4C / La / LaN (X / Y / Z layers) multilayer films. The thickness of one X layer is 1.75 nm, the thickness of one Y layer is 1.15 nm, and the thickness of one Z layer is 0.5 nm.

[0122] Example 2

[0123] The method for preparing Sub / [B4C / La / LaN]^250 multilayer films includes the following steps:

[0124] Background vacuum ≤1×10 -5 Under Pa conditions, the sample disk with a silicon substrate is reset to the 0° position. The substrate is a silicon wafer with a roughness of 0.2 nm. During the fabrication of the multilayer film, the sample disk is kept rotating uniformly, and its rotation speed is determined by the specific thickness of the film layer to be deposited (X / Y / Z layers). The sample disk is as follows: Figure 1 As shown, target 4 is an empty target, target 1 is B4C, and targets 2 and 3 are La.

[0125] When the sample disk rotates 0-90°, a B4C layer is deposited on the Si substrate using pulsed DC sputtering. Parameters include: glide target deposition method, target purity ≥99.5%, argon working gas, preferably 0.15 Pa, and preferably 500 W sputtering power.

[0126] When the sample disk rotates 90-180°, a La layer is deposited on the B4C layer using pulsed DC sputtering. The parameters include: the coating method is grazing target, the target purity is ≥99.5%, the working gas is argon, the working pressure is preferably 0.15 Pa, and the sputtering power is preferably 80W.

[0127] When the sample tray rotates 180°, the controller detects the angle signal from the position sensor and controls the N2 valve to release gas in a sinusoidal opening manner; the nitrogen release method is as follows: Figure 2 As shown in "N2-sine".

[0128] When the sample disk rotates 180-270°, the N2 flow rate increases from 0 sinusoidal to 5 sccm. The LaN layer is prepared on the La layer by pulsed DC sputtering. The parameters include: the coating method is grazing target, the target purity is ≥99.5%, the working gas is a nitrogen-argon mixture, the working pressure is preferably 0.19 Pa, and the sputtering power is preferably 120 W.

[0129] When the sample rotates to 360°, the preparation of one cycle of the thin film is completed. Argon gas is continuously released at a constant flow rate throughout one rotation of the sample disk. This process is repeated 250 times to obtain 250 cycles of B4C / La / LaN (X / Y / Z layers) multilayer films. The thickness of one X layer is 1.75 nm, the thickness of one Y layer is 1.15 nm, and the thickness of one Z layer is 0.5 nm.

[0130] Example 3

[0131] The method for preparing Sub / [B4C / La / LaN]^250 multilayer films includes the following steps:

[0132] Background vacuum ≤1×10 -5 At Pa, the sample disk with the silicon substrate is reset to the 0° position. The substrate is a silicon wafer with a roughness of 0.2 nm. During the fabrication of the multilayer film, the sample disk is kept rotating uniformly. The rotation speed is determined by the specific thickness of the film layer (X / Y / Z layer) to be deposited. The sample disk is as follows: Figure 1 As shown, target 4 is an empty target, target 1 is B4C, and targets 2 and 3 are La.

[0133] When the sample disk rotates 0-90°, a B4C layer is deposited on the Si substrate using pulsed DC sputtering. The parameters include: glide target deposition method, target purity ≥99.5%, argon working gas, preferably 0.15 Pa working pressure, and preferably 500 W sputtering power.

[0134] When the sample disk rotates 90-180°, a La layer is deposited on the B4C layer using pulsed DC sputtering. The parameters include: the coating method is grazing target, the target purity is ≥99.5%, the working gas is argon, the working pressure is preferably 0.15 Pa, and the sputtering power is preferably 80W.

[0135] When the sample tray rotates 180°, the controller detects the angle signal from the position sensor and controls the N2 valve to release gas linearly. The nitrogen release method is as follows: Figure 2 As shown in “N2-linear”.

[0136] When the sample disk rotates 180-270°, the N2 flow rate increases linearly from 0 to 5 sccm. The LaN layer is prepared on the La layer by pulsed DC sputtering. The parameters include: the coating method is grazing target, the target purity is ≥99.5%, the working gas is a nitrogen-argon mixture, the working pressure is preferably 0.19 Pa, and the sputtering power is preferably 120 W.

[0137] When the sample rotates to 360°, the preparation of one cycle of the thin film is completed. Argon gas is continuously released at a constant flow rate throughout one rotation of the sample disk. This process is repeated 250 times to obtain 250 cycles of B4C / La / LaN (X / Y / Z layers) multilayer films. The thickness of one X layer is 1.75 nm, the thickness of one Y layer is 1.15 nm, and the thickness of one Z layer is 0.5 nm.

[0138] Example 4

[0139] The method for preparing Sub / [B4C / La / LaN]^250 multilayer films includes the following steps:

[0140] Background vacuum ≤1×10 -5 At Pa, the sample disk with the silicon substrate is reset to the 0° position. The substrate is a silicon wafer with a roughness of 0.2 nm. During the fabrication of the multilayer film, the sample disk is kept rotating uniformly. The rotation speed is determined by the specific thickness of the film layer (X / Y / Z layer) to be deposited. The sample disk is as follows: Figure 1 As shown, target 4 is an empty target, target 1 is B4C, and targets 2 and 3 are La.

[0141] When the sample disk rotates 0-90°, a B4C layer is deposited on the Si substrate using pulsed DC sputtering. The parameters include: glide target deposition method, target purity ≥99.5%, argon working gas, preferably 0.15 Pa working pressure, and preferably 500 W sputtering power.

[0142] When the sample disk rotates 90-180°, a La layer is deposited on the B4C layer using pulsed DC sputtering. The parameters include: the coating method is grazing target, the target purity is ≥99.5%, the working gas is argon, the working pressure is preferably 0.15 Pa, and the sputtering power is preferably 80W.

[0143] When the sample tray rotates 180°, the controller detects the angle signal from the position sensor and controls the N2 valve to release gas in a rectangular opening manner. The nitrogen release method is as follows: Figure 2 As shown in "N2-rectangle".

[0144] When the sample disk rotates 180-270°, the N2 flow rate is maintained at 10 sccm. The LaN layer is prepared on the La layer by pulsed DC sputtering. The parameters include: the coating method is grazing target, the target purity is ≥99.5%, the working gas is a nitrogen-argon mixture, the working pressure is preferably 0.19 Pa, and the sputtering power is preferably 120 W.

[0145] When the sample rotates to 360°, the preparation of one cycle of the thin film is completed. Argon gas is continuously released at a constant flow rate throughout one rotation of the sample disk. This process is repeated 250 times to obtain 250 cycles of B4C / La / LaN (X / Y / Z layers) multilayer films. The thickness of one X layer is 1.75 nm, the thickness of one Y layer is 1.15 nm, and the thickness of one Z layer is 0.5 nm.

[0146] Comparative Example 1

[0147] The method for preparing Sub / [B4N4C / La / LaN]^250 multilayer films includes the following steps:

[0148] Background vacuum ≤1×10 -5 At Pa, the sample disk with the silicon substrate is reset to the 0° position. The substrate is a silicon wafer with a roughness of 0.2 nm. During the fabrication of the multilayer film, the sample disk is kept rotating uniformly. The rotation speed is determined by the specific thickness of the film layer (X / Y / Z layer) to be deposited. The sample disk is as follows: Figure 1 As shown, target 4 is an empty target, target 1 is B4C, and targets 2 and 3 are La.

[0149] When the sample disk rotates 0-90°, a B4C layer is deposited on the Si substrate using pulsed DC sputtering. The parameters include: glide target deposition method, target purity ≥99.5%, working gas is a nitrogen-argon mixture with a nitrogen-argon flow ratio of 1:2, working pressure preferably 0.19 Pa, and sputtering power preferably 500 W.

[0150] When the sample disk rotates 90-180°, a La layer is deposited on the B4C layer using pulsed DC sputtering. The parameters include: the coating method is grazing target, the target purity is ≥99.5%, the working gas is a nitrogen-argon mixture with a nitrogen-argon flow ratio of 1:2, the working pressure is preferably 0.19 Pa, and the sputtering power is preferably 80 W.

[0151] When the sample disk rotates 180-270°, a LaN layer is prepared on the La layer by pulsed DC sputtering. The parameters include: the coating method is grazing target, the target purity is ≥99.5%, the working gas is a nitrogen-argon mixture, the nitrogen-argon flow ratio is 1:2, the working pressure is preferably 0.19 Pa, and the sputtering power is preferably 120 W.

[0152] When the sample rotates to 360°, the preparation of one cycle of the thin film is completed. Throughout the rotation of the sample disk, the nitrogen and argon mixed gas is vented at the same flow rate. The above steps are repeated 250 times to obtain 250 cycles of B4N4C / La / LaN (X / Y / Z layers) multilayer films.

[0153] Comparative Example 2

[0154] The method for preparing Sub / [B4C / La]^250 multilayer films includes the following steps:

[0155] Background vacuum ≤1×10 -5 At Pa, the sample disk with the silicon substrate is reset to the 0° position. The substrate is a silicon wafer with a roughness of 0.2 nm. During the fabrication of the multilayer film, the sample disk is kept rotating uniformly, and its rotation speed is determined by the specific thickness of the film layer (X / Y layer) to be deposited. The sample disk and... Figure 1 The difference between the sample disks shown is that targets 3 and 4 are empty targets, target 1 is B4C, and target 2 is La.

[0156] When the sample disk rotates 0-90°, a B4C layer is deposited on the Si substrate using pulsed DC sputtering. The parameters include: glide target deposition method, target purity ≥99.5%, argon working gas, preferably 0.15 Pa working pressure, and preferably 500 W sputtering power.

[0157] When the sample disk rotates 90-180°, a La layer is deposited on the B4C layer using pulsed DC sputtering. The parameters include: the coating method is grazing target, the target purity is ≥99.5%, the working gas is argon, the working pressure is preferably 0.15 Pa, and the sputtering power is preferably 80W.

[0158] When the sample rotates to 360°, the preparation of one cycle of the thin film is completed. Argon gas is continuously released at a constant flow rate throughout one rotation of the sample disk. The above steps are repeated 250 times to obtain 250 cycles of B4C / La (X / Y layer) multilayer films. The thickness of one X layer is 1.6 nm, and the thickness of one Y layer is 1.8 nm.

[0159] Example 5

[0160] The method of Example 1 was repeated, except that target 1 was Si, targets 2 and 3 were Mo, and target 4 was an empty target. This process was repeated for 50 cycles to obtain a 50-cycle Si / Mo / MoN (X / Y / Z layer) multilayer film. The thickness of one X layer was 4.17 nm, the thickness of one Y layer was 2.28 nm, and the thickness of one Z layer was 0.5 nm.

[0161] Comparative Example 3

[0162] The method of Comparative Example 1 was repeated, except that target 1 was Si, targets 2 and 3 were Mo, and target 4 was an empty target. This process was repeated for 50 cycles to obtain 50-cycle Si3N4 / Mo / MoN (X / Y / Z layer) multilayer films.

[0163] Comparative Example 4

[0164] The method of Comparative Example 2 was repeated, except that target 1 was Si, target 2 was Mo, and targets 3 and 4 were empty targets. This process was repeated for 50 cycles to obtain 50-cycle Si / Mo (X / Y layer) multilayer films.

[0165] Example 6

[0166] The method of Example 1 was repeated, except that target 1 was Al, targets 2 and 3 were Ti, and target 4 was an empty target. This process was repeated for 40 cycles to obtain a 40-cycle Al / Ti / TiN (X / Y / Z layer) multilayer film. The thickness of layer X was 6.47 nm, layer Y was 2.28 nm, and layer Z was 0.5 nm.

[0167] Comparative Example 5

[0168] The method of Comparative Example 1 was repeated, except that target 1 was Al, targets 2 and 3 were Ti, and target 4 was an empty target. This process was repeated for 40 cycles to obtain 40-cycle AlN / Ti / TiN (X / Y / Z layer) multilayer films.

[0169] Comparative Example 6

[0170] The method of Comparative Example 2 was repeated, except that target 1 was Al, target 2 was Ti, and targets 3 and 4 were empty targets. This process was repeated for 40 cycles to obtain 40 cycles of Al / Ti (X / Y layer) multilayer films.

[0171] Reflectivity of multilayer films

[0172] Theoretical reflectivity calculation method: Based on the theory of multilayer film interference in the optical thin film textbook "Modern Optical Thin Film Technology" (Tang Jinfa, Gu Peifu, et al., Zhejiang University Press, 2006), the IMD thin film calculation software was used to calculate the reflectivity results of multilayer films under ideal conditions and under the influence of reactive gases. The above theoretical calculation method is generally applicable in the field of short-wavelength reflective thin films. Furthermore, although the actual reflectivity value may decrease due to the influence of interface quality and changes in the material's refractive index, the relative relationship between the actual and theoretical reflectivity values ​​for different film systems remains unchanged, which is acceptable to those skilled in the art.

[0173] Specific results are as follows Figure 3-5 As shown.

Claims

1. A method for producing a multilayer film, characterized by, The method comprises steps of: (1) depositing an X layer on a substrate in an atmosphere of a working gas; (2) depositing a Y layer on the substrate with the deposited X layer in an atmosphere of the working gas; (3) depositing a Z layer on the substrate with the deposited X and Y layers in an atmosphere of the working gas and a reaction gas; repeating the steps (1) to (3) for a plurality of cycles to obtain the multilayer film; in one cycle of the steps (1) to (3), the reaction gas is introduced before the deposition of the step (2) is completely finished and the deposition of the step (3) starts; the reaction gas is stopped before the deposition of the step (3) is completely finished and the deposition of the step (1) of the next cycle starts; the flow pattern of the reaction gas is selected from a rectangular, a sinusoidal and a linear; the X layer is B4C, Si or Al; the Y layer is La, Mo or Ti; the Z layer is LaN, MoN or TiN; the reaction gas is nitrogen.

2. The method of claim 1, wherein, The method has one or more of the following features: the substrate is Si; the X layer is B4C, the Y layer is La and the Z layer is LaN; or the X layer is Si, the Y layer is Mo and the Z layer is MoN; or the X layer is Al, the Y layer is Ti and the Z layer is TiN; the multilayer film is B4C / La / LaN, Si / Mo / MoN or Al / Ti / TiN; the working gas is argon; the step (1) comprises depositing the X layer using a first target selected from B4C, Si and Al; the step (2) comprises depositing the Y layer using a second target selected from La, Mo and Ti; the step (3) comprises depositing the Z layer using a third target selected from La, Mo and Ti; in the method, the steps (1) to (3) are repeated for 25-250 cycles; the flow of the reaction gas is 1-20 sccm.

3. The method of claim 2, wherein, the first target is B4C, the second target is La and the third target is La; or the first target is Si, the second target is Mo and the third target is Mo; or the first target is Al, the second target is Ti and the third target is Ti.

4. The method as claimed in claim 3, characterized in that, The method has one or more of the following features: in the step (1), the deposition is pulsed direct current magnetron sputtering; In step (1), the base vacuum before magnetron sputtering is < 1 x 10 -5 Pa. in the step (1), the sputtering mode is glancing target; in the step (1), the purity of the first target is ≥ 99.5%; in the step (1), the working pressure is 0.1-0.3 Pa; in the step (1), the sputtering power is 400-650 W; in the step (2), the deposition is pulsed direct current magnetron sputtering; In step (2), the base vacuum before magnetron sputtering is < 1 x 10 -5 Pa. in the step (2), the sputtering mode is glancing target; in the step (2), the purity of the second target is ≥ 99.5%; in the step (2), the working pressure is 0.1-0.3 Pa; in the step (2), the sputtering power is 50-100 W; in the step (3), the deposition is pulsed direct current magnetron sputtering; in the step (3), the sputtering mode is glancing target; in the step (3), the purity of the third target is ≥ 99.5%; in the step (3), the working pressure is 0.1-0.3 Pa; in the step (3), the sputtering power is 100-150 W.

5. A multilayer film periodically stacked, characterized by, Each cycle comprises X / Y / Z layers, the X layer is selected from B4C, Si and Al, the Y layer is selected from La, Mo and Ti, and the Z layer is selected from LaN, MoN and TiN.

6. The multilayer film of claim 5, wherein, The multilayer film has one or more of the following characteristics: Each cycle comprises B4C / La / LaN; or each cycle comprises Si / Mo / MoN; or each cycle comprises Al / Ti / TiN; The multilayer film comprises 25-250 cycles of X / Y / Z layers; The thickness of the X layer is 1.5-6.5 nm; The thickness of the Y layer is 1-2.5 nm; The thickness of the Z layer is 0.1-1 nm; The total thickness of the multilayer film is 3.4-9.5 nm.

7. An apparatus for the reactive magnetron sputter production of multilayer films, characterized in that The device comprises a sample disc provided with a substrate, two or more targets, a rotating system for rotating the sample disc to sequentially pass through each target for magnetron sputtering, a working gas filling system, a reaction gas filling system and a monitoring device for monitoring the rotation angle of the sample disc.

8. The apparatus of claim 7, wherein, The device has one or more of the following characteristics: The device comprises 3 targets, 4 targets, 5 targets or 6 targets; The working gas filling system is an argon gas filling system; The working gas filling system comprises a valve for controlling the filling of working gas; The reaction gas filling system is a nitrogen gas filling system; The reaction gas filling system comprises a valve for controlling the filling of reaction gas; The monitoring device is connected to the reaction gas filling system by an electrical signal.

9. The device of claim 7 or 8, wherein The device comprises 4 targets, which are evenly and symmetrically distributed on the circumference formed by the rotation of the sample disc, and the targets in the counterclockwise direction comprise a first target, a second target, a third target and a fourth target in sequence; The target material on the first target is B4C, the target material on the second target is La, the target material on the third target is La, and the fourth target is empty; or the target material on the first target is Si, the target material on the second target is Mo, the target material on the third target is Mo, and the fourth target is empty; or the target material on the first target is Al, the target material on the second target is Ti, the target material on the third target is Ti, and the fourth target is empty.

10. Use of the method of any one of claims 1-4 or the device of any one of claims 7-9 in the preparation of a multilayer film with high optical contrast and high reflectivity.

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