CN116165848A - Multilayer film material, extreme ultraviolet reflector, and preparation method and application thereof - Google Patents

Abstract

The invention belongs to the technical field of extreme ultraviolet light optical elements, and in particular relates to a multilayer film material, an extreme ultraviolet light reflector and a preparation method and application thereof. The present invention provides a multilayer film material, which includes a stacked periodic unit, and the periodic unit includes sequentially stacked B ₄ C layer, Mo layer, Y layer and Si layer; the two-side layers of the multilayer film material are respectively It is B ₄ C layer and Si layer. The present invention adds a Y layer between the Mo layer and the Si layer, and adds a B ₄ C layer between the Si layer and the Mo layer, which can suppress the diffusion between the Mo layer and the Si layer, thereby improving the Mo layer and the Si layer in the multilayer film material. The sharpness of the boundary improves the reflectivity of the multilayer film material to extreme ultraviolet light.

Description

A kind of multi-layer film material, extreme ultraviolet light reflector and its preparation method and application

technical field

The invention belongs to the technical field of extreme ultraviolet light optical elements, and in particular relates to a multilayer film material, an extreme ultraviolet light reflector and a preparation method and application thereof.

Background technique

The extreme ultraviolet band usually refers to the band from 121 nm to 10 nm (corresponding to photon energy from 10.25 electron volts to 124 electron volts, respectively). With the development of integrated circuits in the direction of miniaturization and high performance, photolithography has become one of the integrated circuit manufacturing processes, and extreme ultraviolet lithography, as a possible way to manufacture VLSI, has attracted considerable attention. The extreme ultraviolet lithography machine is mainly composed of an extreme ultraviolet light source system, an extreme ultraviolet light reflection system and an illumination exposure etching system. The extreme ultraviolet light reflection system is mainly composed of extreme ultraviolet light reflectors, and currently the extreme ultraviolet light reflectors are mainly constructed of Mo/Si multilayer films. At the extreme ultraviolet wavelength of 13.5nm, the optical contrast of Mo and Si is high, and the absorption rate of extreme ultraviolet light is low, which is good for reflecting extreme ultraviolet light. The theoretical peak reflectivity of the Mo/Si multilayer mirror is 74.06%.

After research, it is found that in the extreme ultraviolet reflection system, 10 mirrors are continuously used to project the pattern onto the wafer, and the reflectivity in the final stage is only about 3% at most, and the reflectivity of the multilayer mirror can be increased by 1%. The total throughput of the EUV lithography system is increased by about 15%. In order to improve the utilization rate of extreme ultraviolet light by extreme ultraviolet lithography machine, it is necessary to further improve the reflectivity of extreme ultraviolet reflective film.

Contents of the invention

In view of this, the present invention provides a multilayer film material, an extreme ultraviolet light reflector and its preparation method and application. The multilayer film material provided by the present invention has a high reflectivity to extreme ultraviolet light, and it is used for The extreme ultraviolet light reflector of the extreme ultraviolet lithography machine can improve the utilization rate of the extreme ultraviolet light of the extreme ultraviolet lithography machine.

In order to solve the above-mentioned technical problems, the present invention provides a multilayer film material, which includes a stacked periodic unit, and the periodic unit includes a B ₄ C layer, a Mo layer, a Y layer and a Si layer stacked in sequence; the multilayer film The two-side layers of the material are B ₄ C layer and Si layer respectively.

Preferably, in one periodic unit, the thickness of the B ₄ C layer is 0.48-0.52 nm, the thickness of the Mo layer is 2.22-2.26 nm, the thickness of the Y layer is 0.48-0.52 nm, and the thickness of the Si layer is 3.67-3.71 nm.

Preferably, the thickness of one periodic unit is 6.9-6.98 nm.

Preferably, the number of the period units is 40-60.

The present invention also provides an extreme ultraviolet light reflector, comprising a substrate and a multilayer film on the surface of the substrate, the multilayer film is composed of the multilayer film material described in the above technical solution; the surface of the substrate is directly in contact with the multilayer film B ₄ C layer contacts.

Preferably, the substrate includes a single crystal silicon wafer, quartz or K9 glass;

The roughness of the substrate is 0.28-0.32nm.

The present invention also provides a method for preparing the extreme ultraviolet light reflector described in the above technical solution, comprising the following steps:

A B ₄ C layer, a Mo layer, a Y layer and a Si layer are sequentially plated on the surface of the substrate to form a periodic unit, and the periodic unit is repeatedly plated to form a multilayer film.

Preferably, the plating method includes magnetron sputtering or pulsed laser deposition.

Preferably, when the plating method is magnetron sputtering, the sputtering power for plating the B ₄ C layer is 110-130W, the sputtering power for plating the Mo layer is 40-60W, and the sputtering power for plating the Y layer is The sputtering power is 10-20W, and the sputtering power for plating the Si layer is 90-110W.

The present invention also provides the application of the EUV light reflector described in the above technical solution or the EUV light reflector prepared by the preparation method described in the above technical solution in an EUV lithography machine.

The present invention provides a multilayer film material, which includes a stacked periodic unit, and the periodic unit includes sequentially stacked B ₄ C layer, Mo layer, Y layer and Si layer; the two-side layers of the multilayer film material are respectively It is B ₄ C layer and Si layer. The present invention adds a Y layer between the Mo layer and the Si layer, and adds a B ₄ C layer between the Si layer and the Mo layer, which can suppress the diffusion between the Mo layer and the Si layer, thereby improving the Mo layer and the Si layer in the multilayer film material. The sharpness of the boundary improves the reflectivity of the multilayer film material to extreme ultraviolet light.

Description of drawings

Figure 1 is a schematic diagram of the structure of the extreme ultraviolet light reflector, in which 1 is the substrate, 2 is the B ₄ C layer, 3 is the Mo layer, 4 is the Y layer, 5 is the Si layer, 6 is the periodic unit, and 7 is the multilayer film material ;

FIG. 2 is a graph showing the reflectance curves of the extreme ultraviolet light mirrors prepared in Example 1 and Comparative Examples 1-3.

Detailed ways

The present invention provides a multilayer film material, which includes a stacked periodic unit, and the periodic unit includes sequentially stacked B ₄ C layer, Mo layer, Y layer and Si layer; the two-side layers of the multilayer film material are respectively It is B ₄ C layer and Si layer.

In the present invention, the thickness of the B ₄ C layer in one periodic unit is preferably 0.48-0.52 nm, more preferably 0.5 nm; the thickness of the Mo layer in one periodic unit is preferably 2.22-2.26 nm, more preferably 2.24 nm; The thickness of the Y layer in a periodic unit is preferably 0.48-0.52 nm, more preferably 0.5 nm; the thickness of the Si layer in a periodic unit is preferably 3.67-3.71 nm, more preferably 3.69 nm. In the present invention, the thickness of one periodic unit is preferably 6.9-6.98 nm, more preferably 6.93 nm. In the present invention, the working wavelength and the thickness of one periodic unit preferably satisfy Bragg's formula. In the present invention, when the thickness of one periodic unit is 6.93nm, the multi-layer film material has good reflectivity to extreme ultraviolet light with a wavelength of 13.5nm.

In the present invention, the number of the periodic units is preferably 40-60, more preferably 50-55.

In the present invention, the B ₄ C layer has good thermal stability, which can improve the thermal stability of the multilayer film material.

The present invention preferably adopts the method of magnetron sputtering to prepare the multi-layer film material. In the present invention, the magnetron sputtering is preferably DC magnetron sputtering. In the present invention, the purity of the B ₄ C target for magnetron sputtering B ₄ C layer is preferably 99-99.8%, more preferably 99.5%; the purity of the Mo target for magnetron sputtering Mo layer is preferably 99.9-99.8%. 99.99%, more preferably 99.99%; the purity of the Y target for the magnetron sputtering Y layer is preferably 99.9～99.99%, more preferably 99.99%; the purity of the Si target for the magnetron sputtering Si layer Preferably it is 99.9 to 99.999%, more preferably 99.999%. In the present invention, the sputtering power of the magnetron sputtering B ₄ C layer is preferably 110-130W, more preferably 115-120W; the sputtering power of the magnetron sputtering Mo layer is preferably 40-60W, more preferably 50W ~55W; the sputtering power of magnetron sputtering Y layer is preferably 10~20W, more preferably 15~18W; the sputtering power of magnetron sputtering Si layer is preferably 90~110W, more preferably 95~100W. In the present invention, the sputtering rate of magnetron sputtering B ₄ C layer is preferably 0.06～0.15nm/S, more preferably 0.08nm/S; the sputtering rate of magnetron sputtering Mo layer is preferably 0.12～0.15nm/S 0.43nm/S, more preferably 0.28nm/S; the sputtering rate of magnetron sputtering plating Y layer is preferably 0.08～0.19nm/S, more preferably 0.14nm/S; magnetron sputtering plating Si layer The sputtering rate is preferably 0.16-0.63 nm/S, more preferably 0.42 nm/S. In the present invention, the working gas of the magnetron sputtering is preferably argon, and the purity of the argon is preferably 99.999%; the pressure of the working gas is preferably 0.14-0.16Pa, more preferably 0.15Pa. In the present invention, the background vacuum degree of the magnetron sputtering is preferably 1.8×10 ^-4 to 2.2×10 ^-4 Pa, more preferably 2×10 ^-4 Pa.

The invention uses the magnetron sputtering method to prepare the multilayer film material, which can accurately control the thickness of each layer film and improve the uniformity of the film of each layer, thereby improving the reflectivity of the multilayer film material to extreme ultraviolet light.

The present invention also provides an extreme ultraviolet light reflector, comprising a substrate and a multilayer film on the surface of the substrate, the multilayer film is composed of the multilayer film material described in the above technical solution; the surface of the substrate is directly in contact with the multilayer film B ₄ C layer contacts. In the present invention, the substrate preferably includes a single crystal silicon wafer, quartz or K9 glass, more preferably a single crystal silicon wafer. In the present invention, the single crystal silicon wafer preferably has a 100 crystal orientation. In the present invention, the roughness of the substrate is preferably 0.28-0.32 nm, more preferably 0.3 nm. In the present invention, the roughness of the substrate is defined in the above range to further improve the reflectivity of the extreme ultraviolet light reflector.

In the present invention, Fig. 1 is a structural schematic diagram of the extreme ultraviolet light reflector, wherein, 1 is a substrate, 2 is a B ₄ C layer, 3 is a Mo layer, 4 is a Y layer, 5 is a Si layer, and 6 is a period Unit 7 is a multilayer film.

The present invention also provides a method for preparing the extreme ultraviolet light reflector described in the above technical solution, comprising the following steps:

A B ₄ C layer, a Mo layer, a Y layer and a Si layer are sequentially plated on the surface of the substrate to form a periodic unit, and the periodic unit is repeatedly plated to form a multilayer film.

In the present invention, the plating method preferably includes magnetron sputtering or pulsed laser deposition, more preferably magnetron sputtering. In the present invention, the magnetron sputtering is preferably DC magnetron sputtering. In the present invention, the purity of the B ₄ C target for the B ₄ C layer by magnetron sputtering is preferably 99 to 99.8%, more preferably 99.5%; the Mo target for the Mo layer by magnetron sputtering The purity of the Y target is preferably 99.9～99.99%, more preferably 99.99%; the purity of the Y target for the Y layer by the magnetron sputtering plating is preferably 99.9～99.99%, more preferably 99.99%; the magnetron sputtering plating The purity of the Si target for Si layer production is preferably 99.9 to 99.999%, more preferably 99.999%. In the present invention, when the plating method is magnetron sputtering, the sputtering power for plating the B ₄ C layer is preferably 110-130W, more preferably 115-120W; the sputtering power for plating the Mo layer Preferably 40～60W, more preferably 50～55W; The sputtering power of plating Y layer is preferably 10～20W, more preferably 15～18W; The sputtering power of plating Si layer is preferably 90～110W, more preferably It is 95 ~ 100W. In the present invention, the sputtering rate of magnetron sputtering plating B ₄ C layer is preferably 0.06～0.15nm/S, more preferably 0.08nm/S; the sputtering rate of magnetron sputtering plating Mo layer is preferably 0.12～0.43nm/S, more preferably 0.28nm/S; the sputtering rate of magnetron sputtering plating Y layer is preferably 0.08～0.19nm/S, more preferably 0.14nm/S; The sputtering rate of the Si layer is preferably 0.16 to 0.63 nm/S, more preferably 0.42 nm/S. In the present invention, the working gas of the magnetron sputtering is preferably argon, and the purity of the argon is preferably 99.999%; the pressure of the working gas is preferably 0.14-0.16Pa, more preferably 0.15Pa. In the present invention, the background vacuum degree of the magnetron sputtering is preferably 1.8×10 ^-4 to 2.2×10 ^-4 Pa, more preferably 2×10 ^-4 Pa.

The present invention also provides the application of the EUV light reflector described in the above technical solution or the EUV light reflector prepared by the preparation method described in the above technical solution in an EUV lithography machine.

In order to further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below in conjunction with examples, but they should not be construed as limiting the protection scope of the present invention.

Example 1

Using a single crystal silicon wafer (100 crystal orientation) as the substrate, the roughness of the single crystal silicon wafer is 0.3nm; on the surface of the single crystal silicon wafer, the B ₄ C layer, Mo layer, Y layer and Si layer are plated by magnetron sputtering , repeated magnetron sputtering plating B ₄ C layer, Mo layer, Y layer and Si layer 50 times to obtain extreme ultraviolet light reflector; described magnetron sputtering is DC magnetron sputtering method, background vacuum degree is 2×10 ^-4 Pa, the sputtering power of DC magnetron sputtering B ₄ C layer is 120W, and the sputtering rate is 0.08nm/S; the sputtering power of Mo layer is 50W, and the sputtering rate is 0.28nm/S; The sputtering power of the Y layer is 15W, and the sputtering rate is 0.14nm/S; the sputtering power of the Si layer is 100W, and the sputtering rate is 0.42nm/S; the working gas purity of DC magnetron sputtering is 99.999% argon gas, the working gas pressure is 0.15Pa; the purity of the B ₄ C target for magnetron sputtering is 99.5%, the purity of the Mo target for magnetron sputtering is 99.99%, and the purity of the Y target for magnetron sputtering is 99.99%, the purity of the Si target for magnetron sputtering is 99.999%; the thickness of the B ₄ C layer is 0.50nm, the thickness of the Mo layer is 2.24nm, the thickness of the Y layer is 0.50nm, and the thickness of the Si layer is 3.69nm , that is, the thickness of the periodic unit is 6.93nm; the thickness of the multilayer film material is 346.5nm.

Comparative example 1

The extreme ultraviolet reflector was prepared according to the method of Example 1, except that the order of coating the multilayer film materials on the surface of the substrate was Y layer, Mo layer, B ₄ C layer and Si layer.

Comparative example 2

The extreme ultraviolet light reflector was prepared according to the method of Example 1, except that the roughness of the single crystal silicon wafer was 0.8 nm.

Comparative example 3

The extreme ultraviolet reflector was prepared according to the method of Example 1, except that in the process of coating the multilayer film material on the surface of the substrate, there were only Mo layer and Si layer but no Y layer and B ₄ C layer.

The reflectance curves of the EUV reflectors prepared in Example 1 and Comparative Examples 1-3 were simulated by IMD software, as shown in FIG. 2 . The theoretical reflectances of the EUV mirrors prepared in Example 1 and Comparative Examples 1-3 were calculated according to the reflectance curves, and the results are listed in Table 1.

Table 1 Theoretical reflectance of the EUV reflectors prepared in Example 1 and Comparative Examples 1-3

Example Theoretical reflectance (%) Example 1 74.33 Comparative example 1 72.22 Comparative example 2 70.98 Comparative example 3 74.06

From Table 1 and FIG. 2, it can be seen that the EUV reflector provided by the present invention has higher theoretical reflectivity than the existing EUV reflector. Comparing the results of Example 1 and Comparative Example 1, it can be seen that the stacking order of B ₄ C layer, Mo layer, Y layer and Si layer will affect the reflectivity, only in accordance with the order of B ₄ C layer, Mo layer, Y layer and Si layer in the The surface coating of the substrate can improve the theoretical reflectivity of the extreme ultraviolet light reflector. Comparing the results of Example 1 and Comparative Example 2, it can be seen that the theoretical reflectance of the extreme ultraviolet light reflector can be improved only if the roughness of the substrate is limited in the range of 0.28-0.32 nm. Comparing the results of Example 1 and Comparative Example 3, it can be seen that the intercalation of the Y layer between the Mo layer and the Si layer, and the intercalation of the B ₄ C layer between the Si layer and the Mo layer can suppress the diffusion between the Mo layer and the Si layer, thereby Improve the boundary definition of Mo layer and Si layer in multilayer film materials, and improve the reflectivity of extreme ultraviolet mirrors for extreme ultraviolet light

Although the foregoing embodiment has described the present invention in detail, it is only a part of the embodiments of the present invention, rather than all embodiments, and people can also obtain other embodiments according to the present embodiment without inventive step, these embodiments All belong to the protection scope of the present invention.

Claims (10)

1. A multilayer film material, comprising stacked periodic units, said periodic unit comprising successively stacked B ₄ C layers, Mo layers, Y layers and Si layers; the two-side layers of said multilayer film material are respectively B ₄ C layer and Si layer. 2. The multilayer film material according to claim 1, characterized in that, in one periodic unit, the thickness of the B ₄ C layer is 0.48-0.52 nm, the thickness of the Mo layer is 2.22-2.26 nm, and the thickness of the Y layer is 0.48 nm. ~0.52nm, and the thickness of the Si layer is 3.67~3.71nm. 3. The multi-layer film material according to claim 2, wherein the thickness of one periodic unit is 6.9-6.98 nm. 4. The multilayer film material according to any one of claims 1-3, characterized in that the number of the periodic units is 40-60. 5. An extreme ultraviolet light reflector, comprising a substrate and a multilayer film on the surface of the substrate, characterized in that, the multilayer film is made of the multilayer film material according to any one of claims 1 to 4; the surface of the substrate In direct contact with the B ₄ C layer in the multilayer film. 6. The extreme ultraviolet light reflector according to claim 5, wherein the substrate comprises a single crystal silicon wafer, quartz or K9 glass; The roughness of the substrate is 0.28-0.32nm. 7. the preparation method of extreme ultraviolet light reflecting mirror described in claim 5 or 6, comprises the following steps: A B ₄ C layer, a Mo layer, a Y layer and a Si layer are sequentially plated on the surface of the substrate to form a periodic unit, and the periodic unit is repeatedly plated to form a multilayer film. 8. The preparation method according to claim 7, wherein the plating method comprises magnetron sputtering or pulsed laser deposition. 9. The preparation method according to claim 8, characterized in that, when the plating method is magnetron sputtering, the sputtering power for plating the B ₄ C layer is 110-130W, and the sputtering power for plating the Mo layer The sputtering power is 40-60W, the sputtering power for Y layer plating is 10-20W, and the sputtering power for Si layer plating is 90-110W. 10. The application of the extreme ultraviolet light reflector according to claim 5 or 6 or the extreme ultraviolet light reflector prepared by the preparation method according to any one of claims 7 to 9 in an extreme ultraviolet lithography machine.

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