CN116009130A - LaNx/B 4 C-type extreme ultraviolet multilayer film reflecting mirror and preparation method thereof - Google Patents

Abstract

The invention belongs to the technical field of precision optical elements, and provides a LaNx/B ₄ A C-type extreme ultraviolet multilayer film reflector and a preparation method thereof. Lanx/B of the invention ₄ The C-type extreme ultraviolet multilayer film reflector comprises a base layer and a multicycle LaNx/B layer which are sequentially laminated on a substrate ₄ A layer C and a protective layer; multicycle LaNx/B ₄ The layer C comprises a plurality of LaNx/B layers which are arranged in a lamination way ₄ A layer C; laNx/B ₄ The layer C comprises LaNx layers which are sequentially laminatedAnd B ₄ And C layer. The LaNx/B provided by the invention ₄ C-type extreme ultraviolet multilayer film mirror, compared with La/B in the prior art ₄ C multilayer reflector, doped with N in La layer, reducing LaNx layer and B ₄ Interlayer roughness between C layers, improving LaNx layer and B ₄ The optical contrast of the C layer is improved, and the multicycle LaNx/B ₄ The quality of the layer C improves LaNx/B ₄ Reflectivity of the C-euv multilayer mirror.

Description

A LaNx/B4C extreme ultraviolet multilayer film mirror and its preparation method

technical field

The invention relates to the technical field of dense optical elements, in particular to a LaNx/B ₄ C extreme ultraviolet multilayer film mirror and a preparation method thereof.

Background technique

The continuous reduction in printed feature size in modern semiconductor devices requires a shift to lower operating wavelength values in lithographic processes, and the reduction of this operating wavelength requires the development of new optical multilayer reflective coatings. It is well known that B-based multilayer mirrors provide extremely high theoretical reflectivity near the boron K absorption edge (λ≈6.6 nm). Therefore, La/B ₄ C multilayer mirrors are considered to be the most promising materials for next-generation EUV lithography. However, when the La/B ₄ C multilayer mirror is applied, interdiffusion phenomenon inevitably occurs between each film layer, which will lead to the widening of the multilayer film interface, thereby significantly reducing the performance of the La/B ₄ C multilayer mirror. The actual reflectivity, so that the actual reflectivity is 15-20% lower than the theoretical reflectivity.

Contents of the invention

In view of this, the object of the present invention is to provide a LaNx/B ₄ C extreme ultraviolet multilayer film mirror and a preparation method thereof. The theoretical reflectance of the LaNx/B ₄ C extreme ultraviolet multilayer film reflector provided by the invention is high, and the actual reflectance during application decreases less than the theoretical reflectance.

In order to achieve the above-mentioned purpose of the invention, the present invention provides the following technical solutions:

The invention provides a LaNx/B ₄ C extreme ultraviolet multilayer film reflector, which comprises a primer layer, a multi-period LaNx/B ₄ C layer and a protective layer stacked on a substrate in sequence;

The multi-period LaNx/B ₄ C layer includes several laminated LaNx/B ₄ C layers;

The LaNx/B ₄ C layer includes a LaNx layer and a B ₄ C layer stacked in sequence;

The LaNx layer in the LaNx/B ₄ C layer is in contact with the underlying layer;

In the LaNx layer, 0<x≤1.

Preferably, the total thickness of each period of the LaNx/B ₄ C layer is 3.38 nm.

Preferably, the thickness of the LaNx layer in each period of the LaNx/B ₄ C layer is 1.3 nm, and the thickness of the B ₄ C layer is 2.08 nm.

Preferably, the substrate includes a glass substrate or a silicon wafer.

Preferably, the material of the underlying layer includes Cr, and the thickness of the underlying layer is 5-10 nm.

Preferably, the material of the protective layer is B ₄ C; the thickness of the protective layer is 5-10 nm.

The present invention also provides a preparation method of the LaNx/B ₄ C extreme ultraviolet multilayer film mirror described in the above technical solution, comprising the following steps:

Prepare a primer on the substrate;

sequentially preparing a LaNx layer and a B ₄ C layer on the primer layer, repeating the process of sequentially preparing a LaNx layer and a B ₄ C layer to obtain the multi-period LaNx/B ₄ C layer;

A protective layer is prepared on the multi-period LaNx/B ₄ C layer to obtain the LaNx/B ₄ C extreme ultraviolet multilayer reflector.

Preferably, the preparation method of the first layer is the first DC magnetron sputtering, and the parameters of the first DC magnetron sputtering include: the background vacuum before the first DC magnetron sputtering≤ 9×10 ^-5 Pa, the sputtering method is skimming the target, the purity of the target is ≥99.5%, the working gas is argon, the working pressure is 0.1-0.12Pa, and the sputtering power is 50-80W.

Preferably, the preparation method of the LaNx layer is the second DC magnetron sputtering, the parameters of the second DC magnetron sputtering include: the sputtering method is sweeping the target, the working gas includes argon and nitrogen, and the argon The volume flow rate of the gas is 15-30 sccm, the volume flow rate of the nitrogen gas is 5-60 sccm, the volume flow ratio of the argon gas and nitrogen gas is 3:2-1:2, the target material is a lanthanum target, and the target material is Purity ≥ 99.5%, working pressure 0.1Pa, sputtering power 60-80W;

The preparation method of the B ₄ C layer is the third DC magnetron sputtering, and the parameters of the third DC magnetron sputtering include: the sputtering method is skimming the target, the target is a B ₄ C target, and the target is The purity is ≥99.5%, the working gas is argon, the working pressure is 0.1Pa, and the sputtering power is 100-120W.

Preferably, the preparation method of the protective layer is the fourth DC magnetron sputtering, and the parameters of the fourth DC magnetron sputtering include: the sputtering method is to sweep the target, the purity of the target is ≥99.5%, and the working gas is Argon gas, the working pressure is 0.1Pa, and the sputtering power is 100-120W.

The invention provides a LaNx/B ₄ C extreme ultraviolet multilayer film reflector, which comprises a primer layer, a multi-period LaNx/B ₄ C layer and a protective layer sequentially stacked on a substrate; the multi-period LaNx/B ₄ The C layer includes several LaNx/B ₄ C layers stacked; the LaNx/B ₄ C layer includes LaNx layers and B ₄ C layers stacked in sequence; the LaNx layer and the LaNx layer in the LaNx/B ₄ C layer and the In the LaNx layer, 0<x≤1. The LaNx/B ₄ C extreme ultraviolet multilayer film mirror provided by the present invention, compared with the La/B ₄ C (La layer and B ₄ C layer repetition) in the prior art, is doped with N in the La layer, reducing The interlayer roughness between the LaNx layer and the B ₄ C layer is improved, the optical contrast between the LaNx layer and the B ₄ C layer is improved, and the quality of the multi-period LaNx/B ₄ C layer is improved, which not only makes the LaNx/B ₄ C layer The improvement of the theoretical reflectance of the ultraviolet multilayer reflector also makes the actual reflectance of the LaNx/B ₄ C extreme ultraviolet multilayer reflector decrease by 8-12% compared with the theoretical reflectance.

The present invention also provides a method for preparing the LaNx/B ₄ C extreme ultraviolet multilayer film reflector described in the above technical solution, comprising the following steps: preparing a primer layer on the substrate; sequentially preparing a LaNx layer and a B 4 C layer on the primer layer ₄ C layer, repeating the process of sequentially preparing LaNx layer and B ₄ C layer to obtain the multi-period LaNx/B ₄ C layer; preparing a protective layer on the multi-period LaNx/B ₄ C layer to obtain the LaNx/B 4 C layer /B ₄ C EUV multilayer mirrors. The preparation method provided by the invention is simple to operate.

Description of drawings

Fig. 1 is a structural schematic diagram of the LaNx/B ₄ C extreme ultraviolet multilayer film mirror provided by the present invention, wherein, 1 is a base, 2 is a primer layer, 3 is a multi-period LaNx/B ₄ C layer, and 31 is a LaNx layer ( 0<x≤1), 32 is the B ₄ C layer, and 4 is the protective layer;

Fig. 2 is a comparison chart of the theoretical reflectivity of the LaNx/B ₄ C extreme ultraviolet multilayer mirror obtained in Example 1 and the boron-based multilayer mirror La/B ₄ C obtained in Comparative Example 1;

FIG. 3 is a partially enlarged view of FIG. 2 .

Detailed ways

Fig. 1 is a schematic structural diagram of the LaNx/B ₄ C extreme ultraviolet multilayer film mirror provided by the present invention, wherein 1 is the substrate, 2 is the primer layer, 3 is the multi-period LaNx/B ₄ C layer, 31 is the LaNx layer, 32 is a B ₄ C layer, and 4 is a protective layer.

The structure of the LaNx/B ₄ C extreme ultraviolet multilayer film mirror provided by the present invention will be described in detail below with reference to FIG. 1 .

The invention provides a LaNx/B ₄ C extreme ultraviolet multilayer film reflector, which comprises a primer layer, a multi-period LaNx/B ₄ C layer and a protective layer stacked on a substrate in sequence;

The multi-period LaNx/B ₄ C layer includes several laminated LaNx/B ₄ C layers;

The LaNx/B ₄ C layer includes a LaNx layer and a B ₄ C layer stacked in sequence;

The LaNx layer in the LaNx/B ₄ C layer is in contact with the underlying layer;

In the LaNx layer, 0<x≤1.

In the present invention, unless otherwise specified, the raw materials used in the present invention are preferably commercially available products.

The LaNx/B ₄ C extreme ultraviolet multilayer film mirror provided by the invention includes a substrate. In the present invention, the substrate preferably includes a glass substrate or a silicon wafer. In the present invention, the roughness of the substrate is preferably 0.3-0.4 nm.

The LaNx/B ₄ C extreme ultraviolet multilayer film mirror provided by the present invention includes a primer layer stacked on the substrate. In the present invention, the material of the primer layer preferably includes Cr. In the present invention, the thickness of the primer layer is preferably 5-10 nm, more preferably 6-9 nm, and more preferably 7-8 nm.

The LaNx/B ₄ C extreme ultraviolet multilayer film mirror provided by the present invention includes multi-period LaNx/B ₄ C layers stacked on the underlying layer. In the present invention, the multi-period LaNx/B ₄ C layer includes several LaNx/B ₄ C layers stacked; the LaNx/B ₄ C layer includes LaNx layers and B ₄ C layers stacked in sequence; The LaNx layer in the LaNx/B ₄ C layer is in contact with the underlying layer; in the LaNx layer, 0<x≤1. In the present invention, the total thickness of each period of the LaNx/B ₄ C layer is preferably 3.38 nm. In the present invention, in each period of the LaNx/B ₄ C layer, the thickness of the B ₄ C layer is preferably 2.08 nm, and the thickness of the LaNx layer is preferably 1.3 nm. In the present invention, the number of periods of the multi-period LaNx/B ₄ C layer is preferably 200-250.

The LaNx/B ₄ C extreme ultraviolet multilayer film mirror provided by the present invention includes a protective layer stacked on the multi-period LaNx/B ₄ C layer. In the present invention, the material of the protective layer is preferably B ₄ C. In the present invention, the thickness of the protective layer is preferably 5-10 nm, more preferably 6-9 nm, and more preferably 7-8 nm.

The present invention also provides a preparation method of the LaNx/B ₄ C extreme ultraviolet multilayer film mirror described in the above technical solution, comprising the following steps:

Prepare a primer on the substrate;

sequentially preparing a LaNx layer and a B ₄ C layer on the primer layer, repeating the process of sequentially preparing a LaNx layer and a B ₄ C layer to obtain the multi-period LaNx/B ₄ C layer;

A protective layer is prepared on the multi-period LaNx/B ₄ C layer to obtain the LaNx/B ₄ C extreme ultraviolet multilayer reflector.

The invention prepares a primer layer on a substrate. In the present invention, pretreatment is preferably performed before preparing the primer on the substrate; the pretreatment preferably includes ultrasonic cleaning.

In the present invention, the preparation method of the primer layer is preferably the first DC magnetron sputtering, and the parameters of the first DC magnetron sputtering include: The bottom vacuum is preferably ≤9×10 ^-5 Pa, the sputtering method is preferably skimming the target, the target is preferably a chromium target, the purity of the target is preferably ≥99.5%, the working gas is preferably argon, and the working pressure is preferably 0.1Pa. The radiation power is preferably 50-80W.

After preparing the primer layer, the present invention sequentially prepares a LaNx layer and a B ₄ C layer on the primer layer, and repeats the process of sequentially preparing the LaNx layer and the B ₄ C layer to obtain the multi-period LaNx/B ₄ C layer.

In the present invention, the preparation method of the LaNx layer is preferably the second DC magnetron sputtering, and the parameters of the second DC magnetron sputtering include: the sputtering method is preferably a sweeping target, and the working gas preferably includes argon and Nitrogen, the volume flow rate of the argon gas is preferably 15-30 sccm, the volume flow rate of the nitrogen gas is preferably 5-60 sccm, the volume flow ratio of the argon gas and nitrogen gas is preferably 3:2-1:2, and the target material is preferably It is a lanthanum target, the purity of the target is preferably ≥99.5%, the working pressure is preferably 0.1Pa, and the sputtering power is preferably 60-80W.

In the present invention, the preparation method of the B ₄ C layer is preferably the third DC magnetron sputtering, and the parameters of the third DC magnetron sputtering include: the sputtering method is preferably skimming the target, and the target material is preferably B ₄ C target material, the purity of the target material is preferably ≥99.5%, the working gas is preferably argon, the working pressure is preferably 0.1Pa, and the sputtering power is preferably 100-120W.

In the present invention, the number of repetitions is preferably set according to the required cycle number of the LaNx/B ₄ C layer.

After the multi-period LaNx/B ₄ C layer is obtained, the present invention prepares a protective layer on the multi-period LaNx/B ₄ C layer to obtain the LaNx/B ₄ C EUV multilayer reflector.

In the present invention, the preparation method of the protective layer is preferably the fourth DC magnetron sputtering, and the parameters of the fourth DC magnetron sputtering include: the sputtering method is preferably grazing target, and the target material is preferably B ₄ C The target, the purity of the target is preferably ≥99.5%, the working gas is preferably argon, the working pressure is preferably 0.1Pa, and the sputtering power is preferably 100-120W.

The LaNx/B ₄ C EUV multilayer mirror and its preparation method provided by the present invention will be described in detail below in conjunction with the examples, but they should not be construed as limiting the protection scope of the present invention.

Example 1

A preparation method of a LaNx/B ₄ C extreme ultraviolet multilayer film mirror, the LaNx/B ₄ C extreme ultraviolet multilayer film mirror is designed to be 5° near vertical incidence, comprising the following steps:

A silicon wafer is used as a substrate, and the roughness of the substrate is 0.3nm.

The first DC magnetron sputtering method is used to prepare the underlayer on the substrate. The parameters include: the background vacuum before the preparation of the underlayer is better than 9×10 ^-5 Pa, the sputtering method is a skimming target, and the target is a chromium target ( The purity is 99.95%), the sputtering power is 40W, the working gas is argon, and the working pressure is 0.1Pa.

The second DC magnetron sputtering method is used to prepare a LaNx (0<x≤1) layer on the bottom layer. The parameters include: the sputtering method is to sweep the target, the working gas includes argon and nitrogen, and the volume flow rate of argon is 30 sccm, The volume flow rate of nitrogen gas is 30 sccm, the target material is a lanthanum target (purity is 99.95%), the sputtering power is 60W, and the working pressure is 0.1Pa.

The B ₄ C layer was prepared on the LaNx (0<x≤1) layer by the third DC magnetron sputtering method, and the parameters included: the sputtering method was skimming the target, and the target was a B ₄ C target (purity: 99.5%) , the working gas is argon, the working pressure is 0.1Pa, and the sputtering power is 120W.

The sputtering rate of each material can be determined by grazing incidence X-ray reflectance testing. Knowing the sputtering rate of each material, it can be seen that the thickness of the LaNx (0<x≤1) layer prepared by the second DC magnetron sputtering method is 1.3nm, and the thickness of the B ₄ layer prepared by the third DC magnetron sputtering method is The thickness of the C layer is 2.08 nm; that is, the periodic thickness of the LaNx/B ₄ C layer is 3.38 nm.

The second DC magnetron sputtering method to prepare the LaNx (0<x≤1) layer and the third DC magnetron sputtering method to prepare the B ₄ C layer were repeated 199 times in order to obtain a multi-period LaNx/B ₄ C layer.

The fourth DC magnetron sputtering method was used to prepare the B ₄ C layer on the multi-period LaNx/B ₄ C layer, and the parameters included: the sputtering method was skimming the target, and the target was a B ₄ C target (purity: 99.5%), The working gas is argon, the working pressure is 0.1Pa, and the sputtering power is 120W. The resulting B ₄ C layer had a thickness of 10 nm.

Comparative example 1

A preparation method of boron-based multilayer reflector La/B ₄ C (La layer and B ₄ C layer repeated), boron-based multilayer reflector La/B ₄ C (La layer and B ₄ C layer repeated) is designed as 5° near normal incidence, including the following steps:

A silicon wafer is used as the substrate, and the substrate roughness is 0.3nm.

The first DC magnetron sputtering method is used to prepare the underlayer on the substrate. The parameters include: the background vacuum before the preparation of the underlayer is better than 9×10 ^-5 Pa, the sputtering method is a skimming target, and the target is a chromium target ( The purity is 99.95%), the sputtering power is 40W, the working gas is argon, and the working pressure is 0.1Pa.

The second DC magnetron sputtering method is used to prepare the La layer on the bottom layer, and the parameters include: the sputtering method is grazing the target, the working gas is argon, the target material is a lanthanum target (purity is 99.95%), and the sputtering power is 60W , The working pressure is 0.1Pa.

The B ₄ C layer was prepared on the La layer by the third direct current magnetron sputtering method, and the parameters included: the sputtering method was a skimming target, the target was a B ₄ C target (purity was 99.5%), the working gas was argon, The working pressure is 0.1Pa, and the sputtering power is 120W.

The sputtering rate of each material can be determined by grazing incidence X-ray reflectance testing. Knowing the sputtering rate of each material, it can be seen that the thickness of the La layer prepared by the second DC magnetron sputtering method is 1.3nm, and the thickness of the _B4C layer prepared by the third DC magnetron sputtering method is 2.08nm ; That is, the periodic thickness of the La/B ₄ C layer is 3.38 nm.

The La layer prepared by the second DC magnetron sputtering method and the B ₄ C layer prepared by the third DC magnetron sputtering method were repeated 199 times in order to obtain a multi-period La/B ₄ C layer.

The fourth DC magnetron sputtering method was used to prepare the B ₄ C layer on the multi-period La/B ₄ C layer, and the parameters included: the sputtering method was skimming the target, and the target was a B ₄ C target (purity: 99.5%), The working gas is argon, the working pressure is 0.1Pa, and the sputtering power is 120W. The resulting B ₄ C layer had a thickness of 10 nm.

The theoretical reflectance of the LaNx/B ₄ C EUV multilayer mirror obtained in Example 1 and the boron-based multilayer mirror La/B ₄ C obtained in Comparative Example 1 were measured, and the results are shown in FIGS. 2-3 and Table 1.

Theoretical reflectivity of the mirror obtained in table 1 embodiment 1 and comparative example 1

Example 1 Comparative example 1 Theoretical reflectance 69.1% 68.65%

It can be seen from Table 1 and Figures 2 to 3 that the theoretical reflectance of the LaNx/B ₄ C extreme ultraviolet multilayer mirror obtained in Example 1 is higher than that of the boron-based multilayer mirror La/B ₄ C obtained in Comparative Example 1 Theoretical reflectivity. Although the theoretical reflectance of the LaNx/B ₄ C extreme ultraviolet multilayer mirror is not much higher than the theoretical reflectance of the boron-based multilayer mirror La/B ₄ C obtained in Comparative Example 1, in practical applications, Since the present invention doped N in the La layer, the interlayer roughness between the LaNx layer and the B ₄ C layer was reduced, the optical contrast between the LaNx layer and the B ₄ C layer was improved, and the multi-period LaNx/B ₄ The quality of the C layer makes the actual reflectance of the LaNx/B ₄ C extreme ultraviolet multilayer film reflector only decrease by 8-12% compared with the theoretical reflectance.

The above is only a preferred embodiment of the present invention, it should be pointed out that, for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications can also be made. It should be regarded as the protection scope of the present invention.

Claims (10)

1. LaNx/B ₄ The C-type extreme ultraviolet multilayer film reflector is characterized by comprising a base layer and a multicycle LaNx/B which are sequentially laminated on a substrate ₄ A layer C and a protective layer;

the multicycle LaNx/B ₄ The layer C comprises a plurality of LaNx/B layers which are arranged in a lamination way ₄ A layer C;

the LaNx/B ₄ The layer C comprises LaNx layers and B which are sequentially laminated ₄ A layer C;

the LaNx/B ₄ The LaNx layer in the layer C is contacted with the priming layer;

in the LaNx layer, x is more than 0 and less than or equal to 1.

2. La/B according to claim 1 ₄ A C-type extreme ultraviolet multilayer film mirror characterized in that each period LaNx/B ₄ The total thickness of the C layer was 3.38nm.

3. La/B according to claim 1 or 2 ₄ A C-type extreme ultraviolet multilayer film mirror characterized in that each period LaNx/B ₄ The thickness of the LaNx layer in the layer C is 1.3nm, B ₄ The thickness of C was 2.08nm.

4. The LaNx/B of claim 1 ₄ The C-type extreme ultraviolet multilayer film reflector is characterized in that the substrate comprises a glass substrate or a silicon wafer.

5. The LaNx/B of claim 1 ₄ The C-type extreme ultraviolet multilayer film reflector is characterized in that the material of the base layer comprises Cr, and the thickness of the base layer is 5-10 nm.

6. La/B according to claim 1 ₄ The C-type extreme ultraviolet multilayer film reflector is characterized in that the material of the protective layer is B ₄ C, performing operation; the thickness of the protective layer is 5-10 nm.

7. The Lanx/B composition according to any one of claims 1 to 6 ₄ The preparation method of the C-pole ultraviolet multilayer film reflector is characterized by comprising the following steps of:

preparing a priming layer on a substrate;

sequentially preparing a LaNx layer and a B layer on the priming layer ₄ Layer C, repeatedly and sequentially preparing LaNx layer and layer B ₄ The process of the layer C is used for obtaining the multicycle LaNx/B ₄ A layer C;

in the multicycle La/B ₄ Preparing a protective layer on the layer C to obtain the LaNx/B ₄ A C-euv multilayer film mirror.

8. The method of claim 7, wherein the method of preparing the primer layer is a first dc magnetron sputtering, and the parameters of the first dc magnetron sputtering include: the background vacuum before the first direct current magnetron sputtering is less than or equal to 9 multiplied by 10 ^-5 Pa, sputtering mode is constant power grazing target plating, the purity of target material is more than or equal to 99.5%, working gas is argon, working air pressure is0.1 to 0.12Pa, and the sputtering power is 50 to 80W.

9. The method according to claim 7, wherein the method for preparing the LaNx layer is a second direct current magnetron sputtering, and parameters of the second direct current magnetron sputtering include: the sputtering mode is a target, the working gas comprises argon and nitrogen, the volume flow of the argon is 15-30 sccm, the volume flow of the nitrogen is 5-60 sccm, and the volume flow ratio of the argon to the nitrogen is 3: 2-1: 2, the target material is a lanthanum target, the purity of the target material is more than or equal to 99.5%, the working air pressure is 0.1Pa, and the sputtering power is 60-80W;

the B is ₄ The preparation method of the layer C is third direct current magnetron sputtering, and the parameters of the third direct current magnetron sputtering comprise: the sputtering mode is a grazing target, and the target material is B ₄ And C, the purity of the target material is more than or equal to 99.5%, the working gas is argon, the working air pressure is 0.1Pa, and the sputtering power is 100-120W.

10. The method according to claim 7, wherein the method for preparing the protective layer is fourth direct current magnetron sputtering, and parameters of the fourth direct current magnetron sputtering include: the sputtering mode is a grazing target, the purity of the target is more than or equal to 99.5%, the working gas is argon, the working pressure is 0.1Pa, and the sputtering power is 100-120W.

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