La / c / 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 La / C / B4C extreme ultraviolet multilayer film mirror and a preparation method thereof.The La / C / B4C extreme ultraviolet multilayer film mirror comprises a primer layer and a multi-period La / C / B4C layer which are sequentially and layerwisely arranged on a substrate; the multi-period La / C / B4C layer comprises a plurality of layerwisely arranged La / C / B4C layers; the La / C / B4C layer comprises a La layer, a C layer and a B4C layer which are sequentially and layerwisely arranged; and the La layer in the La / C / B4C layer is in contact with the primer layer. The application introduces the C layer at the B4C-on-La interface, reduces interface diffusion, improves optical contrast, and further improves the theoretical reflectivity of the La / C / 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 particularly relates to a La / C / B4C extreme ultraviolet multilayer film mirror and a preparation method thereof. BACKGROUND

[0002] The concept of extreme ultraviolet lithography as a possible approach to manufacturing ultra-large scale integrated circuits has attracted considerable attention. An extreme ultraviolet lithography machine mainly consists of three parts: an extreme ultraviolet light source system, an extreme ultraviolet light reflection collection system, and an illumination exposure etching system. At present, an extreme ultraviolet lithography (EUVL) device with a wavelength of 13.5 nm has been widely applied to large chip manufacturers, and many research groups have also focused on the development work. At the same time, the next generation of lithography technology with a shorter wavelength of 6.x nm has become a hot research topic. Since most materials exhibit extremely strong absorption in the extreme ultraviolet band, the conventional transmission optical system fails in this wavelength band, so the extreme ultraviolet lithography system adopts a reflection optical system.

[0003] 6.7 nm is in the anomalous dispersion range of the boron optical constant (K absorption edge at lambda = 6.63 nm), and theoretically, the La / B multilayer film mirror has a reflectivity of 80% at normal incidence, which is even higher than that of Mo / Si at lambda = 13.5 nm. Therefore, the La / B4C multilayer film mirror is considered to be the most promising material for the next generation of extreme ultraviolet lithography. However, when the La / B4C multilayer film mirror is actually applied, interdiffusion inevitably occurs between the film layers, which causes the interface of the multilayer film to widen, so that the actual reflectivity of the La / B4C multilayer film mirror decreases by 15-20% compared with the theoretical reflectivity. SUMMARY

[0004] Therefore, the purpose of the present application is to provide a La / C / B4C extreme ultraviolet multilayer film mirror and a preparation method thereof. The La / C / 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 when the La / C / B4C extreme ultraviolet multilayer film mirror is actually applied.

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

[0006] The present application provides a La / C / B4C extreme ultraviolet multilayer film mirror, which comprises a primer layer and a multi-period La / C / B4C layer which are sequentially stacked on a substrate.

[0007] The multi-period La / C / B4C layer comprises a plurality of La / C / B4C layers which are stacked;

[0008] The La / C / B4C layer comprises a La layer, a C layer and a B4C layer which are sequentially stacked.

[0009] The La layer in the La / C / B4C layer is in contact with the undercoat layer.

[0010] Preferably, the thickness of a single period of the La / C / B4C layer is 3.38 nm.

[0011] Preferably, the thickness of the La layer is 1.1 nm, the thickness of the C layer is 0.4 nm, and the thickness of the B4C layer is 1.88 nm.

[0012] Preferably, the material of the undercoat layer comprises Cr, and the thickness of the undercoat layer is 5-10 nm.

[0013] Preferably, the substrate comprises a glass substrate or a silicon wafer.

[0014] The application also provides a preparation method of the La / C / B4C extreme ultraviolet multilayer film mirror.

[0015] An undercoat layer is prepared on the substrate.

[0016] A La layer, a C layer, and a B4C layer are sequentially prepared on the undercoat layer, and the process of sequentially preparing the La layer, the C layer, and the B4C layer is repeated to obtain the La / C / B4C extreme ultraviolet multilayer film mirror.

[0017] Preferably, the preparation method of the undercoat layer is first direct current magnetron sputtering, and the parameters of the first direct current magnetron sputtering comprise: a base vacuum before the first direct current magnetron sputtering is ≤1×10 -4 Pa, the sputtering mode is a glancing target, the purity of the target material is ≥99.5%, the working gas is argon, the working gas pressure is 0.1-0.15 Pa, and the sputtering power is 40-60 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 comprise: the sputtering mode is a glancing target, the target material is a lanthanum target, the purity of the target material is ≥99.5%, the working gas is argon, the working gas pressure is 0.1-0.15 Pa, and the sputtering power is 20-30 W.

[0019] Preferably, the preparation method of the C layer is third direct current magnetron sputtering, and the parameters of the third direct current magnetron sputtering comprise: the sputtering mode is a glancing target, the target material is a C target, the purity of the target material is ≥99.5%, the working gas is argon, the working gas pressure is 0.1-0.15 Pa, and the sputtering power is 50-70 W.

[0020] Preferably, the preparation method of the B4C layer is fourth direct current magnetron sputtering, and parameters of the fourth direct current magnetron sputtering include: a sputtering mode is a target glancing, a target material is a B4C target, the purity of the target material is greater than or equal to 99.5%, a working gas is argon, a working gas pressure is 0.1-0.15 Pa, and a sputtering power is 100-120 W.

[0021] The application provides a La / C / B4C extreme ultraviolet multilayer film mirror, which comprises a primer layer and a multi-period La / C / B4C layer which are sequentially arranged on a substrate.

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

[0023] Figure 1 The La / C / B4C extreme ultraviolet multilayer film mirror provided by the application has the structure as shown in the schematic structural diagram, wherein 1 is a substrate, 2 is a primer layer, 3 is a multi-period La / C / B4C layer, 31 is a La layer, 32 is a C layer, and 33 is a B4C layer.

[0024] Figure 2 The theoretical reflectivity curve of the mirror obtained in Example 1 and Comparative Example 1 is shown in the figure;

[0025] Figure 3 The La / C / B4C extreme ultraviolet multilayer film mirror provided by the application has the structure as shown in the schematic structural diagram, wherein 1 is a substrate, 2 is a primer layer, 3 is a multi-period La / C / B4C layer, 31 is a La layer, 32 is a C layer, and 33 is a B4C layer. Figure 2 The La / C / B4C extreme ultraviolet multilayer film mirror provided by the application has the structure as shown in the schematic structural diagram, wherein 1 is a substrate, 2 is a primer layer, 3 is a multi-period La / C / B4C layer, 31 is a La layer, 32 is a C layer, and 33 is a B4C layer. DETAILED DESCRIPTION

[0026] Figure 1 The La / C / B4C extreme ultraviolet multilayer film mirror provided by the application has the structure as shown in the schematic structural diagram, wherein 1 is a substrate, 2 is a primer layer, 3 is a multi-period La / C / B4C layer, 31 is a La layer, 32 is a C layer, and 33 is a B4C layer.

[0027] The La / C / B4C extreme ultraviolet multilayer film mirror provided by the application has the structure as shown in the schematic structural diagram, wherein 1 is a substrate, 2 is a primer layer, 3 is a multi-period La / C / B4C layer, 31 is a La layer, 32 is a C layer, and 33 is a B4C layer. Figure 1The structural schematic diagram shown in the figure provides a detailed description of the structure of the La / C / B4C extreme ultraviolet multilayer film mirror provided by the application.

[0028] The application provides a La / C / B4C extreme ultraviolet multilayer film mirror, which comprises a primer layer and a multi-period La / C / B4C layer arranged in sequence on a substrate.

[0029] The multi-period La / C / B4C layer comprises a plurality of La / C / B4C layers arranged in sequence.

[0030] The La / C / B4C layer comprises a La layer, a C layer and a B4C layer arranged in sequence.

[0031] The La layer in the La / C / B4C layer is in contact with the primer layer.

[0032] The La / C / B4C extreme ultraviolet multilayer film mirror provided by the application comprises a substrate.

[0033] The La / C / B4C extreme ultraviolet multilayer film mirror provided by the application comprises a primer layer arranged on the substrate.

[0034] The La / C / B4C extreme ultraviolet multilayer film mirror provided by the application comprises a multi-period La / C / B4C layer arranged on the primer layer.

[0035] In the application, the number of periods of the multi-period La / C / B4C layer is preferably 200.

[0036] The application further provides a preparation method of the La / C / B4C extreme ultraviolet multilayer film mirror.

[0037] A primer layer is prepared on the substrate.

[0038] The La / C / B4C extreme ultraviolet multilayer film mirror is prepared by sequentially preparing a La layer, a C layer and a B4C layer on the primer layer, and repeating the process of sequentially preparing the La layer, the C layer and the B4C layer.

[0039] In the present application, the primer layer is prepared on a substrate. In the present application, the roughness of the substrate is preferably 0.3 nm. In the present application, the substrate preferably further comprises a pretreatment before the primer layer is prepared, and the pretreatment preferably comprises ultrasonic cleaning of the substrate.

[0040] After the primer layer is prepared, the La / C / B4C extreme ultraviolet multilayer film mirror is prepared by sequentially preparing a La layer, a C layer and a B4C layer on the primer layer, and repeating the process of sequentially preparing the La layer, the C layer and the B4C layer.

[0041] In the present application, the preparation method of the primer layer is preferably first direct current magnetron sputtering, and the parameters of the first direct current magnetron sputtering include that the base vacuum before the first direct current magnetron sputtering is preferably better than 1×10 -4 Pa, the sputtering mode is preferably target skimming, the target material is preferably a chromium target, the purity of the target material is preferably ≥99.5%, the working gas is preferably argon, the working gas pressure is preferably 0.1-0.15 Pa, the sputtering power is preferably 40-60 W, further preferably 45-55 W, and more preferably 50 W.

[0042] 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 that the sputtering mode is preferably target skimming, the target material is preferably a lanthanum target, the purity of the target material is preferably ≥99.5%, the working gas is preferably argon, the working gas pressure is preferably 0.1-0.15 Pa, and the sputtering power is preferably 20-30 W, further preferably 25 W.

[0043] In the present application, the preparation method of the C layer is preferably third direct current magnetron sputtering, and the parameters of the third direct current magnetron sputtering include that the sputtering mode is preferably target skimming, the target material is preferably a C target, the purity of the target material is preferably ≥99.5%, the working gas is preferably argon, the working gas pressure is preferably 0.1-0.15 Pa, and the sputtering power is preferably 50-70 W.

[0044] In the present application, the preparation method of the B4C layer is preferably fourth direct current magnetron sputtering, and the parameters of the fourth direct current magnetron sputtering include that the sputtering mode is preferably target skimming, the target material is preferably a B4C target, the purity of the target material is preferably ≥99.5%, the working gas is preferably argon, the working gas pressure is preferably 0.1-0.15 Pa, and the sputtering power is preferably 100-120 W, further preferably 105-115 W, and more preferably 110 W.

[0045] In the present application, the number of repetitions is preferably set according to the number of required La / C / B4C layer cycles.

[0046] The La / C / B4C EUV multilayer film mirror and the preparation method thereof provided by the present application will be described in detail below in conjunction with examples, but they should not be understood as limiting the scope of protection of the present application.

[0047] Example 1

[0048] A preparation method of a La / C / B4C EUV multilayer film mirror, the La / C / B4C EUV multilayer film mirror is designed for 5° near-normal incidence, comprising the following steps:

[0049] A silicon wafer is used as the substrate, and the roughness of the substrate is 0.3 nm.

[0050] A first direct current magnetron sputtering method is used to prepare a primer layer (Cr layer) on the substrate, and the parameters include: a base vacuum before the primer layer is prepared is better than 1x10 -4 Pa, the sputtering mode is a glancing target, the target material is a chromium target (with a purity of 99.95%), the working gas is argon, the sputtering power is 40 W, and the working gas pressure is 0.15 Pa.

[0051] A second direct current magnetron sputtering method is used to prepare a La layer on the primer layer, and the parameters include: the sputtering mode is a glancing target, the target material is a lanthanum target (with a purity of 99.95%), the working gas is argon, the sputtering power is 20 W, and the working gas pressure is 0.15 Pa.

[0052] A third direct current magnetron sputtering method is used to prepare a C layer on the La layer, and the parameters include: the sputtering mode is a glancing target, the target material is a C target (with a purity of 99.5%), the working gas is argon, the working gas pressure is 0.15 Pa, and the sputtering power is 50 W.

[0053] A fourth direct current magnetron sputtering method is used to prepare a B4C layer on the C layer, and the parameters include: the sputtering mode is a glancing target, the target material is a B4C target (with a purity of 99.5%), the working gas is argon, the working gas pressure is 0.15 Pa, and the sputtering power is 120 W.

[0054] The sputtering rate of each material can be determined through a glancing incidence X-ray reflection test. Knowing the sputtering rate of each material, it is known that the thickness of the Cr layer prepared by the first direct current magnetron sputtering method is 10 nm, the thickness of the La layer prepared by the second direct current magnetron sputtering method is 1.1 nm, the thickness of the C layer prepared by the third direct current magnetron sputtering method is 0.4 nm, and the thickness of the B4C layer prepared by the fourth direct current magnetron sputtering method is 1.88 nm; that is, the cycle thickness of the La / C / B4C layer is 3.38 nm.

[0055] The first DC magnetron sputtering method, the second DC magnetron sputtering method, the third DC magnetron sputtering method and the fourth DC magnetron sputtering method are repeated 199 times to prepare the Cr layer, the La layer, the C layer and the B4C layer, respectively, to obtain the La / C / B4C extreme ultraviolet multilayer film mirror.

[0056] Comparative Example 1

[0057] Compared with Example 1, all the conditions are the same, and the only difference is that the thickness of the La layer is 1.3 nm, the thickness of the C layer is 0 nm, and the thickness of the B4C layer is 2.08 nm; that is, no C layer is plated, and the total period thickness is kept unchanged by increasing the thickness of the other two layers.

[0058] The theoretical reflectivity of the mirrors obtained in Example 1 and Comparative Example 1 at 6.7 nm is measured, and the results are shown in Table 1 and Figures 2-3 .

[0059] Table 1 Theoretical reflectivity of the mirrors obtained in Example 1 and Comparative Example 1

[0060] Example 1 Comparative Example 1 Theoretical reflectance 69.1％ 68.65％

[0061] As can be seen from Table 1 and Figures 2-3 , the theoretical reflectivity of the La / C / B4C extreme ultraviolet multilayer film is higher than that of the traditional La / B4C extreme ultraviolet multilayer film. Although the theoretical reflectivity of the La / C / B4C extreme ultraviolet multilayer film mirror is not much higher than that of the boron-based multilayer mirror La / B4C obtained in Comparative Example 1, in practical application, since the C layer is introduced at the B4C-on-La interface in the present application, the interface diffusion is reduced, the optical contrast is improved, and the actual reflectivity of the La / C / B4C extreme ultraviolet multilayer film mirror in application is only 10-14% lower than the theoretical reflectivity.

[0062] The above description is only the preferred embodiments of the present application, and it should be pointed out that for ordinary skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A La / C / B4C extreme ultraviolet multilayer film mirror, characterized in that, The La / C / B4C layer is composed of a primer layer and a plurality of La / C / B4C layers which are sequentially stacked on a substrate; The La / C / B4C layer is composed of a primer layer and a plurality of La / C / B4C layers which are sequentially stacked on a substrate; The La / C / B4C layer is composed of a primer layer and a plurality of La / C / B4C layers which are sequentially stacked on a substrate; The La / C / B4C layer is composed of a primer layer and a plurality of La / C / B4C layers which are sequentially stacked on a substrate; The thickness of the La layer is 1.1 nm, the thickness of the C layer is 0.4 nm, and the thickness of the B4C layer is 1.88 nm. The material of the primer layer comprises Cr, and the thickness of the primer layer is 5-10 nm.

2. The La / C / B4C EUV multilayer film mirror according to claim 1, characterized in that The substrate comprises a glass substrate or a silicon wafer.

3. The La / C / B4C EUV multilayer film mirror according to claim 1, characterized in that, The method comprises the following steps:

4. The method of producing a La / C / B4C EUV multilayer mirror according to any one of claims 1 to 3, characterized in that, Preparation of a primer layer on a substrate; Sequential preparation of a La layer, a C layer and a B4C layer on the primer layer, and repeating the process of sequentially preparing a La layer, a C layer and a B4C layer to obtain the La / C / B4C extreme ultraviolet multilayer film mirror. The preparation method of the La layer is second direct current magnetron sputtering, and the parameters of the second direct current magnetron sputtering include: the sputtering mode is a target, the target material is a lanthanum target, the purity of the target material is ≥99.5%, the working gas is argon, the working gas pressure is 0.1-0.15 Pa, and the sputtering power is 20-30 W.

5. The preparation method according to claim 4, characterized in that, The preparation method of the primer 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 purity of the target material is greater than or equal to 99.5%, the working gas is argon, the working gas pressure is 0.1-0.15 Pa, and the sputtering power is 40-60 W.

6. The preparation method according to claim 4, characterized in that, The preparation method of the C layer is third direct current magnetron sputtering, and the parameters of the third direct current magnetron sputtering include: the sputtering mode is a target, the target material is a C target, the purity of the target material is ≥99.5%, the working gas is argon, the working gas pressure is 0.1-0.15 Pa, and the sputtering power is 50-70 W.

7. The preparation method according to claim 4, characterized in that, The preparation method of the B4C layer is fourth direct current magnetron sputtering, and the parameters of the fourth direct current magnetron sputtering include: the sputtering mode is a target, the target material is a B4C target, the purity of the target material is ≥99.5%, the working gas is argon, the working gas pressure is 0.1-0.15 Pa, and the sputtering power is 100-120 W.

8. The preparation method according to claim 4, characterized in that, ​

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