LaNx / La / B4C extreme ultraviolet multilayer film mirror and preparation method thereof

Abstract

The application belongs to the technical field of high-reflectivity extreme ultraviolet elements, and provides a LaNx / La / B4C extreme ultraviolet multilayer film mirror and a preparation method thereof.The LaNx / La / B4C extreme ultraviolet multilayer film mirror comprises a plurality of periodic LaNx / La / B4C layers which are stacked on a substrate; the plurality of periodic LaNx / La / B4C layers comprise a plurality of LaNx / La / B4C layers which are stacked; the LaNx / La / B4C layer comprises a LaNx layer, a La layer and a B4C layer which are stacked in sequence; and the LaNx layer in the LaNx / La / B4C layer is in contact with the substrate. The La layer is introduced between the B4C layer and the LaNx layer to reduce the interaction between the LaNx and the B4C, thereby reducing the interface diffusion to enhance the optical contrast between the layers and improve the theoretical reflectivity of the LaNx / La / B4C extreme ultraviolet multilayer film mirror.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high reflectivity extreme ultraviolet element, and in particular to a LaNx / La / B4C extreme ultraviolet multilayer film mirror and a preparation method thereof. BACKGROUND

[0002] At present, with the development of integrated circuits towards miniaturization and high performance, the concept of extreme ultraviolet lithography as a possible way to manufacture very large scale integrated circuits has attracted considerable attention. Extreme ultraviolet lithography can further reduce the size of integrated circuits, reduce the power consumption of integrated circuits, and improve the production rate of integrated circuits.

[0003] An extreme ultraviolet lithography system mainly consists of three parts: an extreme ultraviolet light source system, an extreme ultraviolet light reflection and collection system, and an illumination, exposure and etching system. The extreme ultraviolet light reflection and collection system needs to be equipped with a high reflectivity multilayer mirror, and the La / B4C multilayer mirror is considered to be the most potential high reflectivity multilayer mirror. However, because the film layers of the La / B4C multilayer mirror are relatively thin and the interface diffusion is serious, the mixing of the thin layers at the interface leads to a decrease in optical contrast, thereby causing the actual reflectivity of the La / B4C multilayer mirror to decrease by 15-20% compared with the theoretical reflectivity in actual application. SUMMARY

[0004] Therefore, the present application aims to provide a LaNx / La / B4C extreme ultraviolet multilayer film mirror and a preparation method thereof. The LaNx / La / B4C extreme ultraviolet multilayer film mirror provided by the present application has high theoretical reflectivity, and the actual reflectivity decreases less compared with the theoretical reflectivity in actual application.

[0005] In order to achieve the above-mentioned application purposes, the present application provides the following technical solutions:

[0006] The present application provides a LaNx / La / B4C extreme ultraviolet multilayer film mirror, which comprises a plurality of periodic LaNx / La / B4C layers stacked on a substrate.

[0007] The plurality of periodic LaNx / La / B4C layers comprise a plurality of LaNx / La / B4C layers stacked one by one.

[0008] The LaNx / La / B4C layer comprises a LaNx layer, a La layer and a B4C layer stacked one by one.

[0009] The LaNx layer in the LaNx / La / B4C layer is in contact with the substrate.

[0010] In the LaNx layer, 0 < x ≤ 1.

[0011] Preferably, the thickness of a single period of the LaNx / La / B4C layer is 3.38 nm.

[0012] Preferably, the thickness of the LaNx layer is 1.15 nm, the thickness of the La layer is 0.3 nm, and the thickness of the B4C layer is 1.93 nm.

[0013] Preferably, the number of periods of the multi-period LaNx / La / B4C layer is 200-250.

[0014] Preferably, the substrate is a glass substrate or a silicon wafer.

[0015] The application also provides a preparation method of the LaNx / La / B4C extreme ultraviolet multilayer film mirror.

[0016] The LaNx layer, the La layer, and the B4C layer are sequentially prepared on the substrate, and the process of sequentially preparing the LaNx layer, the La layer, and the B4C layer is repeated to obtain the LaNx / La / B4C extreme ultraviolet multilayer film mirror.

[0017] Preferably, the preparation method of the LaNx layer is first direct current magnetron sputtering, and the parameters of the first direct current magnetron sputtering include: a base vacuum before the first direct current magnetron sputtering is less than or equal to 1*10-4 Pa, a sputtering mode is a glancing target, a target material is a lanthanum target, a purity of the target material is greater than or equal to 99.5%, working gas includes argon and nitrogen, a volume flow rate of the argon is 15-30 sccm, a volume flow rate of the nitrogen is 5-60 sccm, a volume flow rate ratio of the argon to the nitrogen is 3:2-1:2, a working gas pressure is 0.1 Pa, and a sputtering power is 60-90 W. -4 Pa, a sputtering mode is a glancing target, a target material is a lanthanum target, a purity of the target material is greater than or equal to 99.5%, working gas is argon, a working gas pressure is 0.1-0.12 Pa, and a sputtering power is 15-20 W.

[0018] Preferably, the preparation method of the La layer is second direct current magnetron sputtering, and the parameters of the second direct current magnetron sputtering include: a sputtering mode is a glancing target, a target material is a lanthanum target, a purity of the target material is greater than or equal to 99.5%, working gas is argon, a working gas pressure is 0.1-0.12 Pa, and a sputtering power is 15-20 W.

[0019] Preferably, the preparation method of the B4C layer is third direct current magnetron sputtering, and the parameters of the third direct current magnetron sputtering include: a sputtering mode is a glancing target, a target material is a B4C target, a purity of the target material is greater than or equal to 99.5%, working gas is argon, a working gas pressure is 0.1 Pa, and a sputtering power is 100-120 W.

[0020] Preferably, the roughness of the substrate is 0.3 nm.

[0021] The application provides a LaNx / La / B4C extreme ultraviolet multilayer film mirror, which comprises a plurality of periodic LaNx / La / B4C layers arranged on a substrate in a stacked mode; the plurality of periodic LaNx / La / B4C layers comprise a plurality of LaNx / La / B4C layers arranged in a stacked mode; the LaNx / La / B4C layer comprises a LaNx layer, a La layer and a B4C layer arranged in a stacked mode in sequence; the LaNx layer in the LaNx / La / B4C layer is in contact with the substrate; and 0 < x ≤ 1 in the LaNx layer.

[0022] The application further provides a preparation method of the LaNx / La / B4C extreme ultraviolet multilayer film mirror, which comprises the following steps: sequentially preparing a LaNx layer, a La layer and a B4C layer on a substrate, and repeatedly preparing the LaNx layer, the La layer and the B4C layer in sequence to obtain the LaNx / La / B4C extreme ultraviolet multilayer film mirror. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 A structure schematic diagram of the LaNx / La / B4C extreme ultraviolet multilayer film mirror is provided, wherein 1 is a substrate, 2 is a plurality of periodic LaNx / La / B4C layers, 21 is a LaNx layer, 22 is a La layer, and 23 is a B4C film layer.

[0024] Figure 2 A theoretical reflectivity curve schematic diagram of the mirrors obtained in Example 1 and Comparative Examples 1 and 2 is provided.

[0025] Figure 3 A partial enlarged view of Figure 2 . DETAILED DESCRIPTION

[0026] The application provides a LaNx / La / B4C extreme ultraviolet multilayer film mirror, which comprises a plurality of periodic LaNx / La / B4C layers arranged on a substrate in a stacked mode;

[0027] The plurality of periodic LaNx / La / B4C layers comprise a plurality of LaNx / La / B4C layers arranged in a stacked mode;

[0028] The LaNx / La / B4C layer comprises a LaNx layer, a La layer and a B4C layer arranged in a stacked mode in sequence;

[0029] The LaNx layer in the LaNx / La / B4C contacts the substrate.

[0030] In the LaNx layer, 0 < x ≤ 1.

[0031] The LaNx / La / B4C extreme ultraviolet multilayer film mirror provided by the application comprises a substrate. In the application, the substrate is preferably a glass substrate or a silicon wafer.

[0032] The LaNx / La / B4C extreme ultraviolet multilayer film mirror provided by the application comprises a plurality of LaNx / La / B4C layers stacked on the substrate. In the application, the plurality of LaNx / La / B4C layers comprise a plurality of LaNx / La / B4C layers stacked one by one; the LaNx / La / B4C layer comprises a LaNx layer, a La layer and a B4C layer stacked one by one; the LaNx layer in the LaNx / La / B4C contacts the substrate; and in the LaNx layer, 0 < x ≤ 1. In the application, the thickness of a single period of the LaNx / La / B4C layer is preferably 3.38 nm. In the application, the thickness of the LaNx layer is preferably 1.15 nm, the thickness of the La layer is preferably 0.3 nm, and the thickness of the B4C layer is preferably 1.93 nm.

[0033] In the application, the number of periods of the plurality of LaNx / La / B4C layers is preferably 200-250.

[0034] The application provides a preparation method of the LaNx / La / B4C extreme ultraviolet multilayer film mirror.

[0035] The LaNx layer, the La layer and the B4C layer are prepared on the substrate one by one, and the process of preparing the LaNx layer, the La layer and the B4C layer one by one is repeated to obtain the LaNx / La / B4C extreme ultraviolet multilayer film mirror.

[0036] In the application, the roughness of the substrate is preferably 0.3-0.4 nm.

[0037] In the application, the substrate preferably further comprises ultrasonic cleaning before the LaNx layer is prepared.

[0038] In the application, the preparation method of the LaNx layer is preferably first direct current magnetron sputtering, and the parameters of the first direct current magnetron sputtering include: the base vacuum before the first direct current magnetron sputtering is preferably ≤1×10-6 Pa, the pressure of the first direct current magnetron sputtering is preferably 0.5-1.5 Pa, the power of the first direct current magnetron sputtering is preferably 100-200 W, the sputtering time of the first direct current magnetron sputtering is preferably 1-3 min, the sputtering rate of the first direct current magnetron sputtering is preferably 0.1-0.3 nm / s, and the sputtering temperature of the first direct current magnetron sputtering is preferably 20-30℃. -4The sputtering mode is preferably glancing target, the target material is preferably lanthanum target, the purity of the target material is preferably ≥ 99.5%, the working gas preferably comprises argon and nitrogen, the volume flow rate of the argon is preferably 15-30 sccm, the volume flow rate of the nitrogen is preferably 5-60 sccm, the volume flow rate ratio of the argon and the nitrogen is preferably 3:2-1:2, the working gas pressure is preferably 0.1 Pa, and the sputtering power is preferably 60-90 W, further preferably 70-80 W.

[0039] In the present application, the preparation method of the La layer is preferably second direct current magnetron sputtering, and the parameters of the second direct current magnetron sputtering include: the sputtering mode is preferably glancing target, the target material is preferably lanthanum target, the purity of the target material is preferably ≥ 99.5%, the working gas is preferably argon, and the working gas pressure is preferably 0.1-0.12 Pa.

[0040] In the present application, the preparation method of the B4C layer is preferably third direct current magnetron sputtering, and the parameters of the third direct current magnetron sputtering include: the sputtering mode is preferably glancing target, the target material is preferably B4C target, the purity of the target material is preferably ≥ 99.5%, the working gas is preferably argon, the working gas pressure is preferably 0.1 Pa, and the sputtering power is preferably 100-120 W, further preferably 105-115 W, and more preferably 110 W.

[0041] In the present application, the number of repetitions is preferably set according to the required number of cycles of the LaNx / La / B4C layer.

[0042] The LaNx / La / B4C extreme ultraviolet multilayer film mirror and the preparation method thereof provided by the present application will be described in detail below in conjunction with embodiments, but they should not be understood as limiting the scope of protection of the present application.

[0043] Embodiment 1

[0044] A preparation method of a LaNx / La / B4C extreme ultraviolet multilayer film mirror, comprising the following steps:

[0045] A silicon wafer is used as the substrate, and the roughness of the substrate is 0.3 nm.

[0046] A LaNx(0 -4 Pa, the sputtering mode is glancing target, the target material is lanthanum target (the purity is 99.95%), the working gas comprises argon and nitrogen, the volume flow rate of the argon is 30 sccm, the volume flow rate of the nitrogen is 30 sccm, the sputtering power is 60 W, and the working gas pressure is 0.1 Pa.

[0047] The La layer is prepared on the undercoat layer by the second direct current magnetron sputtering method, and the parameters include: the sputtering mode is target grazing, the target material is a lanthanum target (the purity is 99.95%), the working gas is argon, the sputtering power is 15 W, and the working pressure is 0.1 Pa.

[0048] The B4C layer is prepared on the La layer by the third direct current magnetron sputtering method, and the parameters include: the sputtering mode is target grazing, the target material is a B4C target (the purity is 99.5%), the working gas is argon, the working pressure is 0.1 Pa, and the sputtering power is 120 W.

[0049] The sputtering rate of each material can be determined by the grazing incidence X-ray reflection test. Knowing the sputtering rate of each material, it is known that the thickness of the LaNx(0

[0050] The LaNx(0

[0051] Comparative Example 1

[0052] The difference from Example 1 is that the La layer is not prepared by the second direct current magnetron sputtering method, and the rest of the operations are the same as those in Example 1. The specific preparation method is as follows:

[0053] The silicon wafer is used as the substrate, and the roughness of the substrate is 0.3 nm.

[0054] The LaNx(0 -4 Pa, the sputtering mode is target grazing, the target material is a lanthanum target (the purity is 99.95%), the working gas includes argon and nitrogen, the volume flow rate of argon is 30 sccm, the volume flow rate of nitrogen is 30 sccm, the sputtering power is 60 W, and the working pressure is 0.1 Pa.

[0055] The B4C layer is prepared on the LaNx layer by the third direct current magnetron sputtering method, and the parameters include: the sputtering mode is target grazing, the target material is a B4C target (the purity is 99.5%), the working gas is argon, the working pressure is 0.1 Pa, and the sputtering power is 120 W.

[0056] The sputtering rate of each material is known, and the thickness of the LaNx(0 < x < 1) layer prepared by the first direct current magnetron sputtering method is 1.3 nm, and the thickness of the B4C layer prepared by the third direct current magnetron sputtering method is 2.08 nm; that is, the periodic thickness of the LaNx / B4C layer is 3.38 nm.

[0057] The first direct current magnetron sputtering method is repeated to prepare the LaNx layer, and the third direct current magnetron sputtering method is repeated to prepare the B4C layer 199 times, to obtain the LaNx / B4C extreme ultraviolet multilayer film mirror.

[0058] Comparative Example 2

[0059] The difference from Example 1 is that the first direct current magnetron sputtering method is not used to prepare the LaNx layer, and the remaining operations are the same as those of Example 1, and the specific preparation method is as follows:

[0060] The silicon wafer is used as the substrate, and the roughness of the substrate is 0.3 nm.

[0061] The second direct current magnetron sputtering method is used to prepare the La layer on the primer layer, and the parameters include: the sputtering mode is a target, the target material is a lanthanum target (the purity is 99.95%), the working gas is argon, the sputtering power is 15 W, and the working pressure is 0.1 Pa.

[0062] The third direct current magnetron sputtering method is used to prepare the B4C layer on the La layer, and the parameters include: the sputtering mode is a target, the target material is a B4C target material (the purity is 99.5%), the working gas is argon, the working pressure is 0.1 Pa, and the sputtering power is 120 W.

[0063] The second direct current magnetron sputtering method is repeated to prepare the La layer, and the third direct current magnetron sputtering method is repeated to prepare the B4C layer 199 times, to obtain the La / B4C extreme ultraviolet multilayer film mirror.

[0064] The theoretical reflectivity of the mirrors obtained in Example 1 and Comparative Examples 1-2 is measured, and the results are shown in Table 1. Figures 2-3 and Table 1.

[0065] Table 1 Theoretical reflectivity of the mirrors obtained in Example 1 and Comparative Examples 1-2

[0066] Example 1 Comparative Example 1 Comparative Example 2 Theoretical reflectance 69.54％ 69.1％ 68.65％

[0067] From Figures 2-3As can be seen from Table 1, the theoretical reflectivity of the LaNx / La / B4C extreme ultraviolet multilayer film mirror is 69.54%, and the theoretical reflectivity of the LaNx / B4C extreme ultraviolet multilayer film mirror is 69.1%; it is illustrated that the theoretical reflectivity of the LaNx / La / B4C extreme ultraviolet multilayer film mirror provided by the application is optimized compared with the LaNx / B4C extreme ultraviolet multilayer film mirror. Although the theoretical reflectivity of the LaNx / La / B4C extreme ultraviolet multilayer film mirror is not much improved compared with the LaNx / B4C extreme ultraviolet multilayer film mirror and the La / B4C mirror from the theoretical reflectivity; but in the actual application, since the application is improved on the basis of the La / B4C multilayer film, the La layer is partially nitrided to form LaN, and the un-nitrided part is used as an ultra-thin La barrier layer to reduce the interface diffusion and enhance the optical contrast between the layers, so that the actual reflectivity of the LaNx / La / B4C extreme ultraviolet multilayer film mirror in the application is less than the theoretical reflectivity, and only decreases by 4-8%.

[0068] The above only describes the preferred embodiments of the present application, and it should be noted that those skilled in the art can make some improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A LaNx / La / B4C extreme ultraviolet multilayer film mirror, characterized in that, The multicycle LaNx / La / B4C layers are stacked on the substrate; The multicycle LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; 2. The LaNx / La / B4C EUV multilayer film mirror according to claim 1, characterized in that The LaNx / La / B4C layers are stacked on the substrate; 3. The LaNx / La / B4C EUV multilayer film mirror according to claim 1 or 2, characterized in that The LaNx / La / B4C layers are stacked on the substrate; 4. The LaNx / La / B4C EUV multilayer film mirror of claim 1, wherein The LaNx / La / B4C layers are stacked on the substrate; 5. The method of producing the LaNx / La / B4C EUV multilayer film mirror according to any one of claims 1 to 4, characterized in that, The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; 6. The preparation method according to claim 5, characterized in that, The preparation method of the LaNx layer is first direct current magnetron sputtering, and parameters of the first direct current magnetron sputtering include: a background vacuum before the first direct current magnetron sputtering is less than or equal to 1*10 -4 Pa, the sputtering mode is a glancing target, the target material is a lanthanum target, the purity of the target material is greater than or equal to 99.5%, the working gas includes argon and nitrogen, the volume flow rate of the argon is 15-30 sccm, the volume flow rate of the nitrogen is 5-60 sccm, the volume flow rate ratio of the argon and the nitrogen is 3:2-1:2, the working gas pressure is 0.1 Pa, and the sputtering power is 60-90 W.

7. The preparation method according to claim 5, characterized in that, The LaNx / La / B4C layers are stacked on the substrate; 8. The preparation method according to claim 5, characterized in that, The LaNx / La / B4C layers are stacked on the substrate; 9. The preparation method according to claim 5, characterized in that, The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on the substrate; The LaNx / La / B4C layers are stacked on

Images