JP2000077305A - Reflecting mask and x-ray projection aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reflecting mask for realizing highly precise alignment, and an X-ray projection aligner using this reflecting mask. SOLUTION: Absorbers 3 are formed like patterns on the surface of a multilayer film 2. When X-rays are made incident, the X-rays made incident to the parts where the multilayer film 2 is exposed are reflected, and the X-rays made incident to the absorbers 3 are not reflected. Alignment marks are constituted of reflecting parts 4 and non-reflecting parts 2a of the alignment lights. It is preferable that the reflecting parts 4 be constituted of materials on which the alignment lights are easily reflected. It is necessary to constitute the non- reflecting parts 2a so that the alignment lights cannot be reflected easily, and the materials of the base are constituted based on the constituting materials of the multilayer film 2. Then, reflectivity can be reduced by increasing the surface roughness and causing the incident lights to be scattered. Thus, the alignment marks, in which the contrast of the reflecting parts 4 and the non- reflecting parts 2a is large, can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photomask (mask or reticle, hereinafter simply referred to as "mask") by a mirror projection system such as an X-ray optical system. In the present specification, a mask is a concept including a reticle. The present invention relates to a reflection mask suitable for transferring the above circuit pattern onto a substrate such as a wafer via a reflection type imaging optical system, and an X-ray projection exposure apparatus using these reflection masks.

[0002]

2. Description of the Related Art In an exposure apparatus for manufacturing a semiconductor, a circuit pattern formed on a mask surface as an object surface is formed by using
The image is projected and transferred onto a substrate such as a wafer via an imaging device. A resist is applied to the substrate, and the resist is exposed by exposure to light, and a resist pattern is obtained.

The resolution w of an exposure apparatus is determined mainly by the exposure wavelength λ and the numerical aperture NA of the imaging optical system, and is expressed by the following equation. w = kλ / NA k: constant Therefore, in order to improve the resolution, it is necessary to shorten the wavelength or increase the numerical aperture. Currently, the exposure equipment used in semiconductor manufacturing mainly uses wavelengths.
Using i-line of 365nm, 0.5μm with numerical aperture of about 0.5
Resolution is obtained. Increasing the numerical aperture is
Since it is difficult in optical design, it is necessary to shorten the wavelength of exposure light in order to further improve the resolution in the future. i
The exposure light having a wavelength shorter than that of the line is, for example, an excimer laser.
nm and 193 nm with an ArF excimer laser, so if the numerical aperture is 0.5, then 0.25 with a KrF excimer laser.
With a μm ArF excimer laser, a resolution of 0.18 μm can be obtained. When X-rays having a shorter wavelength are used as exposure light, a resolution of 0.1 μm or less can be obtained at a wavelength of 13 nm, for example.

A conventional exposure apparatus mainly includes a light source, an illumination device, and a projection imaging optical system. The projection image forming optical system includes a plurality of lenses or reflecting mirrors, and forms a pattern on a mask on a wafer.

In order for an exposure apparatus to have a desired resolution, it is necessary that at least the imaging optical system is an optical system having no or almost no aberration. If the imaging optical system has an aberration, the cross-sectional shape of the resist pattern is degraded, adversely affecting the post-exposure process, and causing a problem that the image is distorted.

A conventional semiconductor exposure apparatus has a position detecting device (hereinafter, referred to as a position detecting device) so that a resist pattern can be formed at a predetermined position on a wafer provided with a circuit pattern.
Alignment device). Thereby, the positions of the mask and the wafer are detected, and the positions of the wafer and the mask are respectively adjusted by the wafer stage and the mask stage so that the reduced image of the mask is formed at a desired position on the wafer.

As an alignment device, there is an alignment device having, for example, an optical detection device. In this method, for example, a mark on a wafer is irradiated with illumination light, and the reflected light or the like is detected by a photodetector. When the wafer position changes, the signal output from the detector changes, so that the position of the wafer can be known. Similarly, the mask can be illuminated with illumination light, and the transmitted light and the like can be detected by a photodetector to determine the position of the mask. Since such an alignment apparatus can detect the positions of the marks on the wafer and the mask with high precision, the alignment between the mask and the wafer can be accurately performed.

FIG. 7 is a schematic view of a part of a conventional exposure apparatus using i-line. The apparatus mainly includes a light source / illumination optical system 21, a stage 25 of a mask 24, and a projection imaging optical system 2.
3. Stage 27 of wafer 26, alignment device 2
2, 28 (the alignment device on the wafer side is not shown). The mask 24 is formed with a pattern of the same size or an enlarged size as a pattern to be drawn. Projection imaging optical system 2
Reference numeral 3 denotes a plurality of lenses and the like, and the pattern on the mask 24 is imaged on the wafer 26 by the i-line 29. That is, the imaging optical system 23 has a visual field with a diameter of about 20 mm, and collectively transfers the pattern on the mask 24 onto the wafer 26. The mark position of the mask 24 is detected by the alignment detecting device 28.

The mask 24 has a chromium film 32 arranged in a pattern on the surface of a substrate 31 such as glass as shown in FIG.
3, a chromium pattern is used in the same manner as the circuit pattern. As shown in FIG. 7, the visible light 20 emitted from the alignment device 22 is aligned with the alignment mark 33 on the mask.
a and illuminates the transmitted light 20b with the alignment device 2
8 The alignment device is, for example, a visible light microscope, and detects the image position of the alignment mark 33 by image processing. By looking at the transmission image of the chrome pattern in this manner, a high-contrast image can be obtained, and high detection sensitivity is achieved.

In a conventional exposure apparatus using i-rays or the like, since a projection imaging optical system can be constituted by a lens, an optical system having a visual field of 20 mm square or more can be designed, and a desired area can be obtained. (For example, an area for two semiconductor chips) can be exposed at a time.

On the other hand, if an attempt is made to design an imaging optical system for X-rays in order to obtain a higher resolution, the field of view becomes smaller, and it becomes impossible to expose a desired area at a time. Therefore, a method of exposing a semiconductor chip of 20 mm square or more with an imaging optical system having a small visual field by scanning a mask and a wafer at the time of exposure has been adopted. In this manner, a desired exposure area can be exposed even with the X-ray projection exposure apparatus. For example, in the case of exposure with X-rays having a wavelength of 13 nm, high resolution can be obtained by making the exposure field of view of the projection imaging optical system annular.

FIG. 9 is a schematic view of a part of the X-ray projection exposure apparatus. The apparatus mainly includes an X-ray source 41 and an X-ray illumination optical system 4.
2, stage 45 of mask 44, X-ray projection imaging optical system 4
3. It is composed of a stage 47 for the wafer 46. Mask 4
In FIG. 4, a pattern of the same size or an enlarged size as the pattern to be drawn is formed. The projection imaging optical system 43 includes a plurality of reflecting mirrors 4.
3a to 43d and the like, and the pattern on the mask 44 is imaged on the wafer 46. Reflector 43
On the surfaces of a to 43d, a multilayer film for increasing the reflectance is formed. The projection imaging optical system 43 has a ring-shaped field of view, and transfers a pattern of a ring-shaped region forming a part of the mask 44 onto the wafer 46. The mask 44 is also of a reflective type. At the time of exposure, X-rays 4
8a is converted into an illuminating bright X-ray 48b by the X-ray illuminating optical system 42, the illuminating bright X-ray 48b is irradiated onto the mask 44, and the reflected X-ray 48c is reflected on the wafer 46 through the X-ray projection imaging optical system 43. Incident on By synchronously scanning the mask 44 and the wafer 46 at a constant speed, a desired region (for example, a region for one semiconductor chip) is exposed.

FIG. 10 is a schematic view showing an example of a conventional reflection type mask.
Shown in In this reflective mask, a multilayer film 52 is provided on the surface of a substrate 51, and an absorber 53 for absorbing X-rays is formed thereon in a pattern. Substrate 51
It is preferable to use a member having a small surface roughness. By doing so, the X-ray reflectivity of the multilayer film can be increased. Single crystal silicon is often used as a substrate having a small surface roughness. The absorber 53 is made of a member that easily absorbs X-rays and is easily processed into a pattern. For example, a pattern is formed by using nickel as an absorber and performing pattern processing by lift-off of electrolytic plating. For this reason, in the conventional mask,
The alignment mark 54 is also formed in a pattern on the multilayer film by X.
What arrange | positioned the material which absorbs a wire easily is used.

[0014]

In the case of an X-ray projection exposure apparatus, a reflective mask must be used. The reason is that when a transmission type mask is used,
The absorption of X-rays by the mask substrate increases, and therefore, it is necessary to reduce the thickness of the mask substrate. However, when the mask substrate is thinned, the rigidity of the mask itself is reduced and the pattern is easily distorted. Because. For this reason, in the case of an X-ray projection exposure apparatus, a reflective mask is used as a mask, and a reflective mark is used as an alignment mark. However, a reflective mark is more sensitive than a conventional transmissive mark. There was a problem that accuracy was poor. For example, a case is considered in which a multilayer film in which molybdenum and silicon are alternately laminated is used as the multilayer film, the outermost surface is silicon, and an alignment mark is formed thereon by nickel of the same material as the pattern.

In this case, the difference between the reflectance of nickel and the multilayer film whose surface is formed of silicon is sufficiently large for X-rays, but the reflectance of silicon and nickel in visible light is about 30% and about 50%.
Therefore, if an attempt is made to detect such an alignment mark with visible light, the reflection contrast of the alignment mark becomes low. As a result, in a conventional X-ray projection exposure apparatus using a reflective mask, high-accuracy overlay exposure is not possible. It was difficult. For example, when aluminum is used as a material having a higher reflectivity instead of nickel, the contrast is improved, but it is still insufficient.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides a reflection mask capable of performing high-precision alignment even if it is a reflection type, and an X-ray projection exposure apparatus using the same. Make it an issue.

[0017]

A first means for solving the above-mentioned problem is a reflection mask using at least a multilayer film, which has a circuit pattern to be projected and transferred and an alignment mark. A reflection mask (Claim 1), comprising a reflection portion that reflects light and a non-reflection portion that hardly reflects light, wherein the surface roughness of the non-reflection portion is larger than the surface roughness of the reflection portion.

In this means, the reflectivity of the non-reflective portion is reduced by making the surface roughness of the non-reflective portion larger than the surface roughness of the reflective portion, whereby the reflected light at the reflective portion and the non-reflective portion is reduced. To increase the contrast. Therefore, since the alignment mark is accurately detected by the reflection type alignment mark detector, high-precision and high-speed alignment can be performed even with a reflection type alignment mark. In general, it is desirable that the reflectivity of the material forming the non-reflective portion be smaller than the reflectivity of the material forming the reflective portion. However, depending on the degree of the difference in surface roughness, the two materials are the same. However, even when the former reflectance is higher than the latter reflectance, a sufficient contrast may be obtained.

A second means for solving the above-mentioned problem is:
The first means, wherein the reflecting portion is a patterned thin film member, and the non-reflecting portion is the multilayer film (claim 2).

According to this means, the pattern-like thin film member forming the reflection portion can be formed by the same sputtering as the multilayer film forming the non-reflection portion, thereby simplifying the manufacturing process. Further, in the transfer pattern, since the surface roughness of the multilayer film serving as the reflection surface is roughened and used as it is, the manufacturing process is also simplified in this respect.

In particular, if the material forming the reflection portion is the same as the material forming the mask pattern (the material absorbing X-rays), the reflection portion of the alignment mark can be formed simultaneously with the formation of the mask pattern. .

A third means for solving the above-mentioned problem is:
The first means, wherein the reflection portion is a thin film member formed on a multilayer film, and the non-reflection portion is another thin film member formed on the thin film member. (Claim 3).

In this means, the thin film member forming the reflection portion of the alignment mark is formed on a multilayer film serving as the reflection portion in the mask pattern, and the thin film member forming the reflection portion is further formed on the thin film member forming the reflection portion. Another thin film member that forms a non-reflective portion is formed. Therefore, the material of the thin film member forming the reflection portion and the material of the thin film member forming the non-reflection portion can be selected relatively freely, and the contrast of the alignment mark can be increased.

A fourth means for solving the above-mentioned problem is:
An X-ray projection exposure apparatus using the reflection mask according to the first to third means (Claim 4).

According to this means, since the position of the alignment mark of the mask can be detected with high precision, the alignment of the mask can be performed accurately and quickly.
Therefore, an X-ray exposure apparatus with high throughput can be provided.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic sectional view of the mask according to the first embodiment of the present invention. In FIG. 1, 1 is a substrate, 2 is a multilayer film, 2a is a non-reflection part of an alignment mark, 3 is an absorber, and 4 is a reflection part of an alignment mark.

The mask includes a substrate 1, a multilayer film 2, an absorber 3,
It is composed of an alignment mark composed of the non-reflection part 2a and the reflection part 4. The substrate 1 is a flat plate on which a multilayer film 2 is formed. As the multilayer film 2, a material and a film thickness that reflect the X-rays of the wavelength to be exposed at a high reflectance are selected. The surface of the substrate 1 is polished smoothly so that the interface and the surface of the multilayer film become smooth. By doing so, the X-ray reflectivity of the multilayer film can be increased.

Absorbers 3 are formed in a pattern on the surface of the multilayer film 2. When X-rays enter here, the X-rays incident on the portion where the multilayer film 2 is exposed are reflected, and the X-rays incident on the absorber 3 are not reflected. That is, of the X-rays that have entered the mask, those that have entered other than the absorber 3 formed in a pattern are reflected. On the other hand, an alignment mark is formed in a part of the region outside the region where the absorber pattern is formed, such as the peripheral portion of the mask.

The alignment mark comprises a reflection part 4 for alignment light and a non-reflection part 2a. The reflecting section 4 is preferably made of a material that easily reflects the alignment light. For example, when the alignment light is visible light, using a metal such as aluminum or platinum increases the reflectance. Further, it is preferable that the surface of the reflecting portion has a low surface roughness because the reflectance increases. Generally, the surface of the multilayer film 2 has a very small surface roughness and a high reflectivity. Therefore, it is preferable to use the same film forming means as that for forming the multilayer film 2.

On the other hand, it is necessary to make the non-reflection portion 2a difficult to reflect the alignment light. However, since the material of the base is determined by the constituent material of the multilayer film 2, the reflectance for the alignment light like the reflection portion is different. It is difficult to select a material based on the Therefore, the reflectance is reduced by increasing the surface roughness and scattering the incident light. By making the surface roughness at least larger than the surface roughness of the reflection part 4, the reflectance is reduced and the reflection contrast is increased. In general, the surface roughness of the reflecting portion 4 is often larger than the surface roughness of the multilayer film 2 in general. Therefore, in order to make the surface roughness of the non-reflection portion larger than the surface roughness of the reflection portion, it is necessary to provide a means for increasing the surface roughness of the non-reflection portion.

In order to increase the surface roughness of the non-reflective portion, for example, the surface may be ground. At this time, a method is preferred in which the cutting speed is microscopically uneven so that the surface roughness is increased. For example, the surface roughness can be increased by using a blast method in which fine particles such as glass beads are sprayed on a surface to be processed and cut. At this time, blast processing or the like is performed only on the alignment pattern portion. For example, a method is employed in which the exposed pattern portion is covered with a protective film such as a resist during processing.

FIG. 2 shows an example of a manufacturing process of the reflection type mask shown in FIG. In the following drawings, the same reference numerals are given to the same components as those shown in the preceding figures in the section of the embodiment of the invention, and the description thereof will be omitted. FIG.
Is a resist.

First, a multilayer film 2 is formed on the surface of a substrate 1,
The area other than the area where the alignment pattern is formed is covered with the resist 5 (a). Next, the surface of the multilayer film 2 is shaved by a blast method,
The non-reflection portion 2a is formed by increasing the roughness (b). After the resist 5 is peeled off, the reflector 4 and the absorber 3 constituting the pattern are formed in a pattern (c).

It is preferable to use a material or a forming method that has a small surface roughness. For example, the reflection section 4 may be formed of polyimide. Since polyimide is liquid when applied, even if the surface roughness of the substrate surface is large, the surface roughness after patterning can be reduced. In particular, if photosensitive polyimide is used, pattern processing can be easily performed. Further, a coating for improving the reflectance may be applied to the surface of the polyimide. The material to be coated is preferably a material having a high reflectance of alignment light,
When the alignment light is visible light, a metal material such as aluminum or platinum is preferable.

The means for increasing the surface roughness is not limited to the blast method. An etching method such as reactive ion etching or ion beam etching may be used. The material for forming the reflection section is not limited to polyimide. PSG (Phospho-sili
A material having excellent surface flatness such as cate glass) may be used. Further, the processing procedure is not limited to the one shown in FIG. 2, and it is also possible to increase the roughness by forming only a non-reflective portion after forming a reflective portion in advance.

FIG. 3 is a schematic sectional view of a mask according to the second embodiment of the present invention. In FIG. 3, 6 is a thin film, 6
a is a reflection part, 7 is a non-reflection part. The mask is composed of a substrate 1, a multilayer film 2, an absorber 3, and an alignment mark including a thin film 6 and a non-reflective portion 7. The substrate 1 is a flat plate on which a multilayer film 2 is formed. The multilayer film 2 is formed of a material and a film thickness that reflect X-rays of the wavelength to be exposed at a high reflectance. In addition, the surface of the substrate 1 is polished smoothly so that the interface and the surface of the multilayer film 2 are smoothed. By doing so, the X-ray reflectivity of the multilayer film 2 can be increased.

The absorber 3 is formed in a pattern on the surface of the multilayer film. When X-rays enter here, the multilayer film 2
The X-rays incident on the portion where is exposed are reflected, and the X-rays incident on the absorber 3 are not reflected. That is, X incident on the mask
Some of the lines are reflected.

On the other hand, an alignment mark is formed in a portion other than the region where the absorber pattern is formed, such as the peripheral portion of the mask. The alignment mark includes a thin film 6 and a non-reflective portion 7. Since the surface of the thin film 6 becomes the reflecting portion 6a, it is preferable that the thin film 6 be made of a material that easily reflects the alignment light. For example, when the alignment light is visible light, using a metal such as aluminum or platinum increases the reflectance. Further, it is preferable that the surface of the reflecting portion has a low surface roughness because the reflectance increases. Generally, multilayer film 2
Since the surface has extremely low surface roughness and high reflectance, it is preferable to use the same film forming means as that for forming the multilayer film 2. In particular, as a film formation method, an apparatus used for forming a multilayer film (an ion beam sputtering apparatus, a magnetron sputtering apparatus, or the like) is preferably used because surface roughness is reduced.

The non-reflection section 7 makes it difficult to reflect the alignment light. It is preferable to use a material that can be easily processed into a pattern and does not easily reflect alignment light. Furthermore, the reflectance of the surface of the non-reflective portion 7 decreases as the surface roughness increases. When the surface roughness is at least larger than the surface roughness of the reflecting portion 6a, the reflection contrast increases.

FIG. 4 is a schematic view of an X-ray projection exposure apparatus according to an embodiment of the present invention. In FIG. 4, 10
Is an alignment light, 11 is an X-ray source, 12 is an illumination optical system,
13 is a projection imaging optical system, 13a to 13d are reflecting mirrors, 14
Is a mask, 15 is a mask stage, 16 is a wafer, 17
Is a wafer stage, 18 is an alignment detection device, 19
Is an X-ray.

The apparatus mainly includes an X-ray source 11, an X-ray illumination optical system 12, an X-ray projection imaging optical system 13, a stage 15 for holding a mask 14, a wafer stage 17 for holding a wafer 16, and an alignment detecting device. 18. The mask 13 is formed with a pattern of the same size or an enlarged size as a pattern to be drawn. The X-ray projection imaging optical system 15 is configured by a plurality of reflecting mirrors and the like.
6 is formed. The X-ray projection imaging optical system 15 has a ring-shaped field of view or the like, and transfers a pattern of a partial area of the mask 14 onto a wafer 16. During exposure,
A desired area is exposed by synchronously scanning the mask and the wafer at a constant speed. The X-ray projection imaging optical system 13 includes a plurality of reflecting mirrors 13a to 13d that reflect X-rays.
It consists of. In order to improve the reflectivity of X-rays, it is preferable to coat the surface of the reflecting mirror with a multilayer film.

As the mask 13, a reflection type mask according to the present invention as shown in FIGS. 1 and 3 is used. The alignment detecting device 18 is a device for optically detecting the position of an alignment mark on the mask 14, and has an illumination optical system for illuminating the mark and a detection optical system for detecting light from the mark. For example, the alignment device is a visible light microscope, and the alignment light 10 emitted from the alignment device is
Is irradiated onto the alignment mark, and the reflected image is captured by a CCD or the like through an optical system.

The X-ray projection exposure apparatus according to the present invention has the structure shown in FIG.
Since the reflective mask as shown in FIG. 3 is used, the alignment mark can be detected with high contrast. Therefore, the position of the alignment mark can be detected with high accuracy, and the alignment of the mask can be performed accurately and at high speed, so that the transfer accuracy and throughput can be increased.

[0044]

Embodiments of the present invention will be described below.

Example 1 A reflection type mask as shown in FIG. 1 was manufactured. This embodiment will be described again with reference to FIG. The mask includes a substrate 1, a multilayer film 2, an absorber 3,
It was composed of an alignment mark composed of the non-reflection part 2a and the reflection part 4. The substrate 1 was a silicon single crystal flat plate whose surface was polished to a roughness of 2 angstroms rms. A multilayer film 2 in which molybdenum and silicon were alternately laminated was formed thereon. The multilayer film was produced by an ion beam sputtering method. The surface roughness of the multilayer film was 3 angstroms rms.

On the surface of the multilayer film, the absorber 3 and the reflection part 4 of the alignment mark were formed in a pattern. Each pattern was formed of chromium and was manufactured by a lift-off method. The surface roughness of the reflection part 4 was 1 nmrms. Further, the non-reflection portion 2a of the alignment light has its surface roughness reduced.
The reflectivity of the alignment light was reduced by about 0.1 μm rms.

FIG. 5 shows a manufacturing process of such a reflection mask. First, as shown in (a), a multilayer film 2 as described above is formed on a substrate 1 and an absorber 3 and a reflecting portion 4 made of chromium are formed on the multilayer film 2 in the same manner as in the related art. The portion of the mold mask surface where the exposure pattern was formed was covered with a resist 5 (b). Next, the exposed portion of the multilayer film 2 was etched by reactive ion etching of a gas containing F (fluorine) as a main component (c). At this time, since the multilayer film is etched by the F-based gas, its surface roughness is reduced, and the non-reflection portion 2a is formed. On the other hand, since the chromium is not etched by the F-based gas, the surface roughness of the reflecting portion 4 hardly changes. Finally, the resist 7 is removed.
The mask is completed (FIG. D). When the alignment light reflectance of the non-reflection portion 2a of this mask was measured, it was reduced to 1/5 or less as compared with the conventional mask.

Further, projection exposure was performed using the present mask. The exposure apparatus used was the one shown in FIG. The X-ray exposure wavelength is 13 nm. The X-rays reflected by the mask 14 pass through the projection imaging optical system 13 and reach the wafer 16, and the mask pattern is reduced and transferred onto the wafer 16. The imaging optical system 13 includes four reflecting mirrors 13a to 13d.
A is 0.1, the reduction magnification is 1/4, and it has an annular exposure field of view. The reflecting mirrors 13a to 23d have an aspherical reflecting surface shape, and the surface thereof is coated with a multilayer film made of molybdenum and silicon for improving the reflectivity of X-rays.
During exposure, the mask 14 and the wafer 16 are scanned by stages 15 and 17, respectively. The scanning speed of the wafer is synchronized so that it is always 1/4 of the scanning speed of the mask. As a result, the pattern on the mask can be transferred onto the wafer in a reduced size of 1/4.

This apparatus is provided with an alignment device 18 for a mask. This alignment apparatus is a kind of visible light microscope, and irradiates an alignment mark with visible white light having a center wavelength of 500 nm and captures a reflection image of the mark with a CCD camera. A similar device is provided for the wafer and can detect marks on the wafer. Thus, the positional relationship between the mark on the mask and the mark on the wafer was detected. Since the mask mark has a higher contrast than the conventional mark, alignment can be performed in a short time. Therefore, a device with high throughput and high accuracy could be manufactured.

On the other hand, when a conventional reflective mask is used, much time is required for alignment detection. If an attempt is made to expose at a high throughput, the yield is lowered due to low alignment accuracy, and the productivity cannot be increased.

Example 2 A reflection type mask as shown in FIG. 3 was manufactured. This embodiment will be described again with reference to FIG. The mask was composed of an alignment mark formed of the substrate 1, the multilayer film 2, the absorber 3, the thin film 6 (reflection portion 6a), and the non-reflection portion 7. The substrate 1 was a silicon single crystal flat plate whose one surface was polished to a roughness of 2 angstroms rms. A multilayer film 2 in which molybdenum and silicon were alternately laminated was formed thereon. The multilayer film was produced by an ion beam sputtering method. The surface roughness of the multilayer film 2 was 3 angstroms rms.

On the surface of the multilayer film 2, an absorber 3 and a thin film 6 whose surface serves as a reflection portion 6a of an alignment mark were formed in a pattern. The thin film 6 was formed of aluminum and had a surface roughness of 0.7 nm rms. The absorber 3 forming the pattern and the non-reflection portion 7 of the alignment mark were both formed of nickel, and were manufactured by lift-off of a plating method. Further, the non-reflection portion 7 of the alignment light has a surface roughness of about 0.1 μm rms to reduce the reflectance of the alignment light.

FIG. 6 shows the manufacturing process of the present mask. First, an aluminum thin film 6 was formed on a portion of the surface of the multilayer film 2 where an alignment mark was to be formed (a). Aluminum was produced by the same sputtering method as that for forming the multilayer film. Further, a transfer pattern and a resist pattern 5 of an alignment pattern were formed on the mask surface, and nickel films 3 and 7 were formed in portions where no resist was formed by plating (b). At this time,
Plating was performed under conditions that would increase the surface roughness of nickel. Next, a portion of the nickel film which becomes the non-reflection portion 7 of the alignment mark was irradiated with an ion beam of argon to etch the nickel surface, thereby further increasing the surface roughness (c). Finally, the resist was stripped (d).

When the alignment light reflectance of the non-reflection portion 7 of the present mask was measured, it was reduced to 1/3 or less as compared with the conventional mask. Further, the alignment mark reflecting portion 6a
Has increased 1.8 times as compared with the conventional one. Further, the same projection exposure as in Example 1 was performed using this mask. As a result, a high-throughput and high-precision device could be manufactured.

Example 3 A reflection type mask as shown in FIG. 1 was manufactured. This embodiment will be described again with reference to FIG. The mask includes a substrate 1, a multilayer film 2, an absorber 3,
It was composed of an alignment mark composed of the non-reflection part 2a and the reflection part 4. The substrate 1 was a silicon single crystal flat plate whose surface was polished to a roughness of 2 angstroms rms. Here, a multilayer film 2 in which molybdenum and silicon were alternately laminated was formed. The multilayer film was produced by an ion beam sputtering method. The surface roughness of the multilayer film is 3 Å
ms.

On the surface of the multilayer film 2, an absorber 3 and a reflection portion 4 of an alignment mark were formed in a pattern. The absorber 3 constituting the pattern was formed of nickel, and the reflection part 4 of the alignment mark was formed of photosensitive polyimide. The surface of the photosensitive polyimide was coated with platinum (not shown) in order to improve the reflectance of the alignment mark. The surface roughness of platinum is about 1 nmrms. Further, the non-reflection portion 2a of the alignment light has a surface roughness of 0.5 μm.
The reflectivity of the alignment light was reduced at about rms.

The process for reducing the surface roughness of the non-reflective portion will be described again with reference to FIG. First, a multilayer film 2 was formed on a substrate 1, and a resist film 5 was applied to a region of the surface of the multilayer film 2 where a circuit pattern was to be formed (a). Fine particles of glass beads were sprayed on the surface with a blast device to cut the surface (b).
As a result, the surface roughness of the exposed portion of the multilayer film 2 was increased, and the non-reflection portion 2a was formed. After the resist 5 was peeled off, photosensitive polyimide was applied and processed into a pattern by exposure and development. Further, the surface of the reflecting portion 4 was coated with a platinum film (not shown) in order to improve the reflectance of the alignment light. The platinum film was formed by a lift-off method by covering the portions other than the reflecting portion with a resist in advance so that only the reflecting portion 4 could be coated. Finally, an absorber to be exposed and transferred was formed in a pattern by plating (c).

When the alignment light reflectance of the non-reflective portion of this mask was measured, it was reduced to 1/10 or less as compared with the conventional mask. Further, the same projection exposure as in Example 1 was performed using this mask. High-precision devices with high throughput could be manufactured.

Example 4 A reflection type mask as shown in FIG. 1 was manufactured. This embodiment will be described again with reference to FIG. The mask includes a substrate 1, a multilayer film 2, an absorber 3,
It was composed of an alignment mark composed of the non-reflection part 2a and the reflection part 4. The substrate 1 was a silicon single crystal flat plate whose surface was polished to a roughness of 2 angstroms rms. Here, a multilayer film 2 in which molybdenum and silicon were alternately laminated was formed. The multilayer film was produced by an ion beam sputtering method. The surface roughness of the multilayer film is 3 Å
ms.

On the surface of the multilayer film, the absorber 3 and the reflection part 4 of the alignment mark were formed in a pattern. The absorber 3 constituting the pattern was formed of nickel, and the reflection part 4 of the alignment mark was formed of PSG. The surface of the PSG was coated with chrome (not shown) for improving the reflectance of the alignment mark. Chrome has a surface roughness of 1 nmrm
s. Furthermore, the non-reflection part 2a of the alignment light
Reduced the reflectivity of alignment light by setting the surface roughness to about 0.5 μm rms. The process of reducing the surface roughness of the non-reflective portion will be described again with reference to FIG. First, substrate 1
A multilayer film 2 was formed thereon, and a resist film 5 was applied to an area of the surface where a circuit pattern was to be formed (a). Fine particles of glass beads were sprayed on the surface with a blast device to cut the surface (b). As a result, the surface roughness of the exposed portion of the multilayer film 2 increases, and the non-reflection portion 2a is formed.
After the resist 5 was peeled off, PSG was applied by a spin coater to form the reflection part 4. A chromium film was formed on the surface, a resist was applied, and chromium was processed into a pattern by exposure and development (not shown). Perform dry etching using this chromium pattern as an etching mask,
The PSG was processed into a pattern.

When the alignment light reflectance of the non-reflective portion of the present mask was measured, it was reduced to 1/5 or less as compared with the conventional mask. Further, the same projection exposure as in Example 1 was performed using this mask. As a result, a high-throughput and high-precision device could be manufactured.

[0062]

As described above, according to the first aspect of the present invention, the reflectance of the non-reflection portion is increased by making the surface roughness of the non-reflection portion larger than the surface roughness of the reflection portion. Because it is lowered, the alignment mark
High-precision detection is possible, and high-precision and high-speed alignment is possible even with a reflection type. This reflective mask is particularly suitable for use in an X-ray exposure apparatus having an alignment apparatus using visible light.

According to the second aspect of the present invention, since the pattern-like thin film member forming the reflection portion can be formed by the same sputtering as the multilayer film forming the non-reflection portion, the manufacturing process is simplified.

According to the third aspect of the present invention, the material of the thin film member forming the reflection portion and the material of the thin film member forming the non-reflection portion can be selected relatively freely, and the contrast of the alignment mark can be increased. can do.

In the invention according to claim 4, claim 1
Since the reflection mask according to the third aspect of the present invention is used, mask alignment can be performed accurately and quickly, and an X-ray exposure apparatus with high throughput can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a mask according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating an example of a manufacturing process of the reflective mask illustrated in FIG. 1;

FIG. 3 is a schematic sectional view of a mask according to a second embodiment of the present invention.

FIG. 4 is a schematic diagram of an X-ray projection exposure apparatus as an example of an embodiment of the present invention.

FIG. 5 is a diagram illustrating an example of a manufacturing process of the reflective mask illustrated in FIG. 1;

FIG. 6 is a diagram illustrating an example of a manufacturing process of the reflective mask illustrated in FIG. 3;

FIG. 7 is a conceptual diagram showing a part of a conventional exposure apparatus using i-line.

FIG. 8 is a schematic view of a mask used in a conventional exposure apparatus using i-line.

FIG. 9 is a conceptual diagram showing a part of a conventional X-ray projection exposure apparatus.

FIG. 10 is a schematic view showing an example of a conventional reflective mask.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... board | substrate, 2 ... multilayer film, 2a ... non-reflection part of an alignment mark, 3 ... absorber, 4 ... reflection part of an alignment mark, 5 ... resist, 6 ... thin film, 6a ... reflection part, 7 ... non-reflection part, Reference numeral 10: alignment light, 11: X-ray source, 12: illumination optical system, 13: projection imaging optical system, 13a to 13d: reflecting mirror, 14: mask, 15: mask stage, 16: wafer, 17: wafer stage, 18 ... Alignment detector, 19 ... X-ray

Claims (4)

[Claims] 1. A reflection mask using at least a multilayer film, which has a circuit pattern to be projected and transferred and an alignment mark, wherein the alignment mark is composed of a reflection part that reflects alignment light and a non-reflection part that is difficult to reflect. A reflection mask, wherein the surface roughness of the non-reflection portion is larger than the surface roughness of the reflection portion. 2. The reflection mask according to claim 1, wherein the reflection portion is a patterned thin film member, and the non-reflection portion is the multilayer film. 3. The thin-film member formed on a multilayer film and the non-reflective portion is another thin-film member formed on the thin-film member. Reflection mask. 4. One of claims 1 to 3
An X-ray projection exposure apparatus using the reflection mask described in the above section.