JPH07218701A - Antireflection film - Google Patents

Abstract

PURPOSE:To provide an antireflection film having small absorption by designing the film so that refractive indexes of a low refractive index layer and of a high refractive index layer to a specific wavelength light satisfy a specific condition. CONSTITUTION:This film is successively provided with a first to sixth layers from an air side to a substrate side. The first, the third and the fifth layers are composed of the low refractive index layers, the second, the forth and the sixth layers are composed of the high refractive index layers. The high refractive index layers contain Al2O3 and the low refractive index layers contain SiO2. When refractive indexes of the low refractive index layers and refractive indexes of the high refractive index layers to 248nm wavelength light are respectively denoted by NL and NH, conditions of 1.45<=NL<=51.55 and 1.60<=NH1.80 are satisfied.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an antireflection film, and particularly to a wavelength of 30.
The present invention relates to an antireflection film effective for ultraviolet light having a wavelength of 0 nm or less and visible light having a wavelength of 550 to 650 nm.

[0002]

2. Description of the Related Art A conventional antireflection film for ultraviolet rays has a high refractive index layer and a low refractive index layer made of a fluoride, and is disclosed in, for example, Japanese Patent Application Laid-Open No. 61-77002 of the present applicant.

[0003]

The antireflection film of the above publication has excellent antireflection properties, but an antireflection film having a smaller absorption and a wider antireflection band is required.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide an antireflection film having a smaller absorption.

In order to achieve this object, the antireflection film of the present invention is provided with Al ₂ O _{3 in} order from the air side to the substrate side.
A high refractive index layer containing, a low refractive index layer containing SiO ₂ ,
1.45 ≦ N _L ≦ 1.55 1.60 ≦ N _H ≦ 1.80, where N _L and N _H are the refractive indices of the low refractive index layer and the high refractive index layer with respect to light having a wavelength of 248 nm. And the high refractive index layer is made of Al ₂ O.
_{3. The} absorption is reduced by using SiO ₂ for the low refractive index layer. Further, the antireflection effect is enhanced by providing a plurality of alternating layers of the high and low refractive index layers.

Further, another antireflection film of the present invention comprises a high refractive index layer containing Al ₂ O ₃ in order from the air side to the substrate side, in order to obtain a good antireflection effect while achieving the above object.
When the refractive index of the low refractive index layer and the high refractive index layer for a light having a wavelength of 248 nm is N _L and N _H , respectively, which has a low refractive index layer containing SiO ₂ , 1.45 ≦ N _L ≦ 1 .55 1.60 ≦ N _H ≦ 1.80, and has a six-layer structure, and the first, third, and fifth layers are the low-refractive-index layer in order from the air side, and the first layer in order from the air side. The second, fourth, and sixth layers are characterized by being composed of the high-refractive-index layer. By using Al ₂ O _{3 for} the high-refractive-index layer and SiO ₂ for the low-refractive-index layer, absorption is reduced, and 6 layers By adopting a structure, absorption is suppressed to a small level and a good antireflection effect is obtained.

Another antireflection film of the present invention is a high refractive index layer containing Al ₂ O ₃ in order from the air side to the substrate side, in order to obtain a good antireflection effect while achieving the above object.
When the refractive index of the low refractive index layer and the high refractive index layer for a light having a wavelength of 248 nm is N _L and N _H , respectively, which has a low refractive index layer containing SiO ₂ , 1.45 ≦ N _L ≦ 1 .55 1.60 ≦ N _H ≦ 1.80, and has a six-layer structure, and the first, third, and fifth layers are the low-refractive-index layer in order from the air side, and the first layer in order from the air side. The second, fourth and sixth layers are composed of the high refractive index layer, and the optical thickness of the first to sixth layers (refractive index × geometrical thickness)
And D1, D2, D3, D4, D5, D6, respectively, satisfy 50 ≤ D1 ≤ 85 35 ≤ D2 ≤ 75 45 ≤ D3 ≤ 75 145 ≤ D4 ≤ 240 80 ≤ D5 ≤ 125 75 ≤ D6 ≤ 120 Which is characterized in that the high refractive index layer is made of Al ₂ O.
_{3. The} absorption is reduced by using SiO ₂ for the low refractive index layer, and the absorption is suppressed by the 6-layer structure to obtain a good antireflection effect, and the optical film thickness of each layer is set as described above. As a result, an antireflection effect against both ultraviolet rays and visible light is obtained.

Each of the layers of the antireflection film of the present invention is mainly formed of Al ₂ O ₃ and SiO ₂ .
A layer containing O ₂ , N, Ar or the like in the process of film formation is also applied.

The several antireflection films of the present invention are formed on the light passage surface (refraction surface) of an optical system such as a lens to exert the above effect. Therefore, the optical system including the antireflection film of the present invention is an excellent optical system in which the lens does not generate reflected light.

Therefore, the exposure apparatus for forming the pattern of the original plate on the substrate by the optical system, and the pattern of the original plate is projected on the substrate by illuminating the pattern of the original plate by the optical system. Or an exposure apparatus characterized by illuminating an original plate by this optical system and forming an image of the pattern of the original plate on a substrate, thereby providing an exposure apparatus having high resolution. By using the device manufacturing method characterized by including the step of transferring the device pattern of the original plate onto the substrate by using the exposure apparatus of 1., a device with a high degree of integration can be provided.

[0011]

FIG. 1 is a schematic view showing an example of the antireflection film of the present invention. The antireflection film of this embodiment is designed to have an antireflection effect on ultraviolet rays and visible light.

As shown in FIG. 1, the antireflection film of this embodiment has a six-layer structure, uses SiO ₂ for the low refractive index layer and Al ₂ O ₃ for the high refractive index layer, and has an air side. From the substrate side to the substrate side, the respective refractive index layers are laminated in the order of low, high, low, high, low and high.

The antireflection film of this embodiment has a wavelength of 248.
When the low-refractive index layer and the high-refractive index layer have a refractive index of N _L and N _H , respectively, for light of nm, 1.45 ≦ N _L ≦ 1.55 (1) 1.60 ≦ N It is designed to satisfy _H ≤1.80 (2).

Further, in the antireflection film of this embodiment, the first layer to the sixth layer are determined in order from the air side, and the optical film thickness (refractive index × geometric film thickness) of the first to sixth layers is determined. D1, D2,
When D3, D4, D5, D6, 50 ≦ D1 ≦ 85 (3) 35 ≦ D2 ≦ 75 (4) 45 ≦ D3 ≦ 75 (5) 145 ≦ D4 ≦ 240 ··· (6) 80 ≦ D5 ≦ 125 (7) 75 ≦ D6 ≦ 120 (8) It is preferable to design.

The antireflection film of this embodiment has a low refractive index layer made of Si.
O ₂ and Al ₂ O ₃ used for the high refractive index layer have small absorption. Also, these materials have good adhesion to the substrate.

Further, since it has a six-layer structure, it is possible to obtain a good antireflection effect while reducing absorption.

By designing to satisfy the above conditions (3) to (8), it is possible to obtain an antireflection effect for both ultraviolet rays and visible light, and to widen the antireflection band in the ultraviolet region.

FIG. 2 is a schematic view showing an optical system in which the antireflection film of the present invention is used, and L ₁ and L ₂ are lenses.
In FIG. 2, the antireflection film of FIG. 1 is formed on the light entrance / exit surfaces of the lenses L ₁ and L ₂ , and the effect of this antireflection film can suppress the generation of harmful light such as flare light. It has an excellent optical system.

The antireflection film shown in FIG. 1 is alternately formed on the substrate (lens surface or the like) by a vapor deposition method or a sputtering method, such as a SiO ₂ film or an Al ₂ film.
It is formed by forming an O ₃ film. Impurities may be mixed into the film during film formation. For example, in the case of the sputtering method, O ₂ , N, Ar, etc. are mixed into the film. However,
If the refractive index of each layer satisfies the above conditions (1) and (2), the effect of antireflection is hardly impaired even if impurities are mixed in each layer.

Next, specific design examples of the antireflection film of the present invention are shown in Tables 1 to 4 below.

The first design example in Table 1 is an example in which an antireflection film for ultraviolet light having a central wavelength of 248 nm is formed on a quartz glass substrate by a vacuum deposition method, and the refractive index in Table 1 is 24.
It is a refractive index for 8 nm light. FIG. 3 is a diagram showing the reflection characteristics of the first design example.

In the second design example of Table 2, the ultraviolet light having the central wavelength of 248 nm and the wavelength of 5 are used on the quartz glass substrate by the vacuum deposition method.
This is an example in which an antireflection film for visible light of 50 to 650 nm is formed, and the refractive index in Table 2 is the refractive index for light of 248 nm. FIG. 4 is a diagram showing the reflection characteristics of this second design example.

The third design example in Table 3 is an example in which an antireflection film for ultraviolet light having a central wavelength of 248 nm is formed on a quartz glass substrate by a sputtering method, and the refractive index in Table 3 is 24.
It is a refractive index for 8 nm light. FIG. 5 is a diagram showing the reflection characteristic of the third design example.

The fourth design example in Table 4 is that a central wavelength of 248 nm ultraviolet light and a wavelength of 5 are used on a quartz glass substrate by vacuum deposition.
This is an example in which an antireflection film for visible light of 50 to 650 nm is formed, and the refractive index in Table 4 is the refractive index for light of 248 nm. FIG. 6 is a diagram showing the reflection characteristic of the fourth design example.

The antireflection film of each of the first to fourth design examples.
It has a good antireflection effect as shown in FIGS. Further, since SiO ₂ and Al ₂ O ₃ are used as the material and the structure is a 6-layer structure, absorption is small. Also, these materials have good adhesion to the substrate.

[0026]

[Table 1]

[0027]

[Table 2]

[0028]

[Table 3]

[0029]

[Table 4]

FIG. 7 shows a projection exposure apparatus for device manufacturing, which is equipped with an optical system having the antireflection film of the present invention.

In FIG. 7, 10 is an optical axis, 20 is an excimer laser, 30 is an illumination optical system having an aperture stop 30A, 40 is a stage on which the reticle M is mounted, 50 is a projection optical system having an aperture stop 50A, 60 Indicates a stage on which the wafer W is placed. The ultraviolet laser light from the laser 20 is applied to the reticle M via the illumination optical system 30, and the projection optical system 50 projects an image of the device pattern of the reticle M onto the wafer W.

The projection exposure apparatus according to the present embodiment has an illumination optical system 3
The antireflection film of the present invention is formed on both the 0 lens and the lens of the projection optical system 50, and the effect of the antireflection film prevents the reflection of the ultraviolet laser light on the refracting surface of the lens,
Prevents the generation of flare light.

As another embodiment of the projection exposure apparatus, there is an example in which the antireflection film of the present invention is formed on only one of the lens of the illumination optical system 30 and the lens of the projection optical system 50.

In the case where the antireflection film of the present invention having an antireflection effect against both ultraviolet rays and visible light is used for the lens of the projection optical system 50, the projection optical system is operated by a positioning optical system (not shown). When the mark on the wafer W is detected by visible light through the system 50, flare light can be prevented from being generated, and correct mark detection can be performed.

Next, an embodiment of a device manufacturing method using the projection exposure apparatus of FIG. 7 will be described.

FIG. 8 shows a manufacturing flow of a semiconductor device (semiconductor chip such as IC or LSI, liquid crystal panel or CCD).
In step 1 (circuit design), the circuit of the semiconductor device is designed. In step 2 (mask manufacturing), a mask (reticle 304) on which the designed circuit pattern is formed is manufactured.
On the other hand, in step 3 (wafer manufacturing), a wafer (wafer 306) is manufactured using a material such as silicon. Step 4 (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by the lithography technique using the mask and the wafer prepared above. The next step 5 (assembly) is called the post-process, and step 4
Therefore, it is a step of making a chip using the wafer thus prepared, and includes an assembly step (dicing, bonding), a packaging step (chip encapsulation), and the like. In step 6 (inspection), the semiconductor device manufactured in step 5 undergoes inspections such as an operation confirmation test and a durability test. Through these steps, the semiconductor device is completed and shipped (step 7).

FIG. 9 shows the detailed flow of the wafer process. In step 11 (oxidation), the surface of the wafer (wafer 306) is oxidized. Step 12 (CV
In D), an insulating film is formed on the surface of the wafer. In step 13 (electrode formation), electrodes are formed on the wafer by vapor deposition. In step 14 (ion implantation), ions are implanted in the wafer. Step 15 (resist processing)
Then, a resist (photosensitive material) is applied to the wafer. In step 16 (exposure), the projection exposure apparatus exposes the wafer with an image of the circuit pattern of the mask (reticle 304). In step 17 (development), the exposed wafer is developed. In step 18 (etching), parts other than the developed resist are scraped off. In step 19 (resist stripping), the resist that is no longer needed after etching is removed. By repeating these steps, a circuit pattern is formed on the wafer.

By using the manufacturing method of this embodiment, it becomes possible to manufacture a highly integrated device, which was difficult in the past.

[0039]

According to the present invention, a high-refractive index layer containing Al ₂ O ₃ and a low-refractive index layer containing SiO ₂ are provided in this order from the air side to the substrate side. The refractive index of the refractive index layer and that of the high refractive index layer are N _L and N _H , respectively.
In this case, the absorption is reduced by satisfying 1.45 ≦ N _L ≦ 1.55 1.60 ≦ N _H ≦ 1.80. Further, the antireflection effect is enhanced by providing a plurality of alternating layers of the high and low refractive index layers.

Further, according to the present invention, a six-layer structure is further provided,
The first, third, and fifth layers are the low refractive index layers in order from the air side, and the second, fourth, and sixth layers are the high refractive index layers in order from the air side, so that absorption is suppressed small. It has a good antireflection effect.

Further, according to the present invention, the optical film thickness (refractive index × geometric film thickness) of each of the first to sixth layers is further calculated as follows:
When D1, D2, D3, D4, D5, D6, 50 ≦ D1 ≦ 85 35 ≦ D2 ≦ 75 45 ≦ D3 ≦ 75 145 ≦ D4 ≦ 240 80 ≦ D5 ≦ 125 75 ≦ D6 ≦ 120 It has anti-reflection effect against both ultraviolet rays and visible light, and has a wide anti-reflection band against ultraviolet rays.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of an antireflection film of the present invention.

FIG. 2 is a diagram showing an optical system including an antireflection film of the present invention.

FIG. 3 is a diagram showing a reflection characteristic of an antireflection film of a first design example.

FIG. 4 is a diagram showing a reflection characteristic of an antireflection film of a second design example.

FIG. 5 is a diagram showing a reflection characteristic of an antireflection film of a third design example.

FIG. 6 is a diagram showing a reflection characteristic of an antireflection film of a fourth design example.

FIG. 7 is a diagram showing a projection exposure apparatus having an optical system including the antireflection film of the present invention.

FIG. 8 is a diagram showing a manufacturing flow of a device.

FIG. 9 is a diagram showing the wafer process of FIG. 8;

[Explanation of symbols]

L ₁ and L ₂ lens 30 Illumination optical system 50 Projection optical system

Claims (11)

[Claims] 1. Al _{2 in} order from the air side to the substrate side
When a high refractive index layer containing O ₃ and a low refractive index layer containing SiO ₂ are provided, and the refractive indexes of the low refractive index layer and the high refractive index layer with respect to light having a wavelength of 248 nm are N _L and N _H , respectively. , 1.45 ≦ N _L ≦ 1.55 1.60 ≦ N _H ≦ 1.80. 2. The antireflection film according to claim 2, wherein a plurality of alternating layers of the high and low refractive index layers are provided. 3. A six-layer structure, wherein the first, third, and fifth layers in order from the air side are the low refractive index layers, and the second, fourth, and sixth layers in order from the air side are the high layers. The antireflection film according to claim 2, which is formed of a refractive index layer. 4. The optical film thickness (refractive index × geometric film thickness) of each of the first to sixth layers is D1, D2, D3, D4, D, respectively.
5, when D6, 50 ≤ D1 ≤ 85 35 ≤ D2 ≤ 75 45 ≤ D3 ≤ 75 145 ≤ D4 ≤ 240 80 ≤ D5 ≤ 125 75 ≤ D6 ≤ 120 film. 5. An optical system comprising a lens having a refraction surface formed with the antireflection film according to any one of claims 1 to 4. 6. An exposure apparatus which forms an image of a pattern of an original plate on a substrate by the optical system according to claim 5. 7. An exposure apparatus which projects a pattern of the original onto a substrate by illuminating the pattern of the original with the optical system according to claim 5. 8. An exposure apparatus which illuminates an original plate and forms an image of the pattern of the original plate on a substrate by the optical system according to claim 5. 9. A device manufacturing method comprising a step of transferring a device pattern of an original plate onto a substrate by using the exposure apparatus according to any one of claims 6 to 8. 10. A method of manufacturing an antireflection film, comprising forming the low refractive index layer and the high refractive index layer of the antireflection film according to claim 1 by a sputtering method. 11. A method for producing an antireflection film, comprising forming the low refractive index layer and the high refractive index layer of the antireflection film according to claim 1 by a vapor deposition method.