JP2005099571A - Multilayered film reflection mirror, film-deposition method of reflection multilayered film, film-deposition device and exposure device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayered film reflection mirror and the like having thin total film thickness, wherein higher reflectance can be obtained while surface roughness of a reflection multilayered film is reduced. <P>SOLUTION: An Mo/Si multilayered film (a deep layer side multilayered film) 101 consisting of molybdenum and silicon is film-deposited on the surface of a substrate 103 by an ion beam sputtering method. An Mo/Si multilayered film (a surface side multilayered film) 102 is film-deposited on the surface of the deep layer side multilayered film 101 by a low voltage discharge rotary magnet cathode sputtering method which is a kind of a magnetron sputtering method. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a multilayer mirror for use in EUV lithography and the like, a method for forming a reflective multilayer film, a film forming apparatus, and an exposure apparatus. In particular, the present invention relates to a multilayer film reflecting mirror or the like that can obtain a high reflectance while improving the roughness of the optical functional surface (surface).

  With further progress in miniaturization of semiconductor integrated circuit elements, development of projection lithography using soft X-rays having a wavelength of about 11 to 14 nm instead of ultraviolet rays has been advanced (see Non-Patent Document 1). This technique is also recently called EUV (Extreme Ultraviolet, Extreme X-ray, Soft X-ray) lithography. This EUV lithography is expected as a lithography technique having a resolving power of 50 nm or less, which cannot be realized by conventional optical lithography (wavelength of about 190 nm or more).

  In this soft X-ray wavelength band, there is no transparent substance, and the refractive index of the substance is very close to 1, so that a conventional optical element utilizing refraction cannot be used. Instead, a grazing incidence mirror that uses total reflection, or a multilayer film reflector that achieves a high reflectivity by superimposing a large number of reflected light by matching the phase of weak reflected light at the interface is used. Is done.

  In such a multilayer-film reflective mirror, the material suitable for obtaining a high reflectance varies depending on the wavelength band of incident light. For example, in the wavelength band near 13.4 nm, when a Mo / Si multilayer film in which molybdenum (Mo) layers and silicon (Si) layers are alternately stacked is used, a reflectivity of 67.5% can be obtained at normal incidence. it can. In addition, in the wavelength band near 11.3 nm, when a Mo / Be multilayer film in which Mo layers and beryllium (Be) layers are alternately stacked is used, a reflectance of 70.2% can be obtained at normal incidence (non-reflection). Patent Document 2).

  In EUV lithography, in order to increase the processing speed as a system, a multilayer film having high reflectivity is required. Such a multilayer film is formed by magnetron sputtering or ion beam sputtering.

  It is known that the reflectance of the multilayer film varies depending on the film formation method. Non-Patent Document 3 discloses that a Mo / Si multilayer film formed by magnetron sputtering is formed by ion beam sputtering. It has been reported that a slightly higher reflectivity can be obtained. Non-Patent Document 4 reports that a Mo / Si multilayer film formed by a low-pressure discharge rotary magnet cathode sputtering apparatus, which is a kind of DC magnetron sputtering, has a reflectivity exceeding 70%. ing.

  When the cross sections of multilayer films formed by different methods were observed with a transmission electron microscope, the thickness of the interface diffusion layer (the layer formed by the upper layer material entering the lower layer) in these multilayer films was determined. There was a difference. That is, the interfacial diffusion layer of the Mo / Si layer formed by magnetron sputtering is thinner than the interfacial diffusion layer formed by ion beam sputtering, and in particular, molybdenum on the silicon layer. The difference in the thickness of the interface diffusion layer at the interface where the layers were laminated was significant. Such a difference in the thickness of the interfacial diffusion layer is considered to be a cause of an increase in the reflectance of the multilayer film formed by the magnetron sputtering method.

  On the other hand, the multilayer film formed by the ion beam sputtering method has not been reported to have a high reflectivity as high as 70% as in the case of the magnetron sputtering method described above. However, even when the substrate surface is somewhat rough, the multilayer film is formed on the multilayer film. An effect that the surface of the film formed becomes smooth (hereinafter referred to as a surface smoothing effect) has been confirmed. When a multilayer film is formed by ion beam sputtering on a substrate on which foreign matter having a diameter of 30 nm exists as a reflective mask substrate for EUV lithography, the amount of displacement of the multilayer film surface has been reduced to 1/10 of 3 nm. It has been reported. By using the multilayer film formed by ion beam sputtering in this way as a smoothing layer, the multilayer film is formed on the surface of the smoothing layer with reduced influence of foreign matter, thereby producing a multilayer film without defects. Has been proposed (see Non-Patent Document 5).

  By the way, when comparing the surface roughness of a single-layer film of molybdenum and a single-layer film of silicon formed by ion beam sputtering on a silicon wafer, the surface roughness of the molybdenum single-layer film is lower than that of the underlying silicon wafer surface. In contrast to the deterioration, the silicon single layer film hardly changes. From this, it is considered that the contribution of the silicon layer formation is mainly large in the surface smoothing effect at the time of forming the Mo / Si multilayer film.

Daniel A. Tichenor, 21 others, "Recent results in the development of an integrated EUVL laboratory tool", "Proceedings of SPIE), (USA), SPIE, The International Society for Optical Engineering, May 1995, Vol. 2437, p. 292 Claude Montcalm, 5 others, "Multilayer reflective coatings for extreme-ultraviolet lithography", "Proceedings of SPIE", (USA) SPIE (The International Society for Optical Engineering), June 1998, 3331, p. 42 Jos. PH Benschop, 2 others, “Proceedings of SPIE” (USA), The International Society for Optical Engineering (SPIE) July 2000, 3997, p. 34 Masayuki Shiraishi, Noriaki Kamitaka, Katsuhiko Murakami, “Mo / Si multilayers deposited by low pressure rotary magnet cathode sputtering for extreme-ultraviolet lithography”, “Proceedings of SPIE”, (USA), Kokusai Kokko The International Society for Optical Engineering (SPIE), June 2003, Volume 5037, p. 249 Christopher C. Walton, 12 others, “Extreme Ultraviolet Lithography: reflective mask technology”, “Proceedings of SPIE”, (USA), International Society of Optical Engineering (SPIE, The International Society for Optical Engineering, July 2000, Vol. 3997, p. 496

  As described above, in order to obtain a high processing speed in EUV lithography, a high reflectivity is required for the multilayer-film reflective mirror constituting the optical system. The reflectance of the Mo / Si multilayer for EUV lithography currently reported is about 70% at the maximum. By the way, in EUV lithography, when the illumination optical system and the projection optical system are combined, ten or more multilayer mirrors are used, so even if the reflectance of each multilayer mirror is slightly lowered, the optical system There is a problem that the transmission efficiency of EUV light as a whole is significantly reduced. For example, if the reflectance is reduced from 70% to 68%, the amount of light finally reaching the wafer via the optical system is reduced by 20% or more.

  In addition, since the wavelength of EUV light is as short as approximately 11 to 14 nm, it is necessary to reduce the roughness of a fine period in a reflector used for EUV lithography. In order to obtain a reflectivity of 70% with a Mo / Si multilayer film formed by magnetron sputtering, the surface roughness with a period of 1 μm or less must be reduced to about 0.15 nm RMS. It is not easy to manufacture the substrate.

  On the other hand, since the Mo / Si multilayer film formed by the ion beam sputtering method has a surface smoothing effect, if the surface roughness of the substrate is 0.3 nm RMS or less, the influence on the decrease in reflectance is considered to be small. ing. However, as described above, the Mo / Si multilayer film formed by the ion beam sputtering method has a slightly lower reflectance than that formed by the magnetron sputtering method.

  Furthermore, in EUV lithography, a very small wavefront aberration of 0.5 nm RMS is required for the transmission wavefront of the projection optical system. In contrast, an in-plane distribution of the film thickness of each Mo / Si multilayer film formed on the surface of the reflective optical element always has an error even if it is slight. For this reason, the shape error of the surface after the multilayer film is formed increases as the total film thickness of the multilayer film increases even if the relative in-plane distribution error is the same. Therefore, it is desirable that the total film thickness of the multilayer film is as thin as possible.

  In view of the above points, an object of the present invention is to provide a multilayer film reflecting mirror or the like having a thin total film thickness, which can obtain a higher reflectance while reducing the surface roughness of the reflective multilayer film. .

The multilayer film reflector of the present invention is a multilayer film reflector in which a multilayer film formed by laminating two or more kinds of substances having different refractive indexes is formed on a substrate surface, and each of the multilayer film mirrors constituting the multilayer film Some of the films are formed by ion beam sputtering, and the other films are formed by magnetron sputtering.
According to the present invention, it is possible to produce a multilayer film having a surface smoothing effect by the ion beam sputtering method and a high reflectance by the magnetron sputtering method. As a result, a multilayer film having a high reflectance can be formed on a substrate having a relatively large surface roughness.

  In the multilayer mirror described above, the two or more kinds of materials may be molybdenum or a material containing molybdenum and silicon or a material containing silicon.

In the above-described multilayer film reflector, the deep multilayer film near the substrate is formed by ion beam sputtering, and the surface multilayer film near the surface (optical function surface) is formed by magnetron sputtering. be able to.
According to the present invention, the surface smoothing effect can be obtained by forming the deep multilayer film by ion beam sputtering, so that the surface roughness of the multilayer film can be reduced. Furthermore, a multilayer film having a high reflectance can be obtained even on a substrate having a relatively large surface roughness by forming a surface-layer multilayer film on the deep-layer multilayer film by magnetron sputtering.

In the multilayer mirror described above, the total number of layers of the multilayer film formed by the ion beam sputtering method and the magnetron sputtering method is about 40-60 layer pairs, and the total number of layers of the multilayer film is 30-80. % Can be formed by magnetron sputtering.
In this case, since the total number of layers of the multilayer film is 60 pair layers or less, the influence of the in-plane distribution error of the film thickness can be reduced. In addition, since the multilayer film formed by ion beam sputtering reflects the surface roughness of the substrate, the reflectivity may be slightly lowered. The surface roughness of is improved. By forming a multilayer film on the multilayer film having a small (smooth) surface roughness by magnetron sputtering by 30 to 80% of the total number of layers, the reflectance of the entire multilayer film can be increased.

Here, the effect exerted on the reflectance of the entire multilayer film by forming the multilayer film having a high reflectance on the multilayer film having a low reflectance will be described.
FIG. 5A is a graph showing the calculated values of the normal incidence reflectance with respect to EUV light of a Mo / Si multilayer mirror in which a multilayer film having a high reflectance and a multilayer film having a low reflectance are laminated.
In FIG. 5A, the horizontal axis indicates the wavelength of EUV light irradiated perpendicularly to the multilayer film, and the vertical axis indicates the reflectance.
Here, the periodic length of the Mo / Si multilayer film is 6.9 nm, the thickness of the molybdenum layer is 2.8 nm, the thickness of the silicon layer is 4.1 nm, 50 pairs of layers, and the interface roughness is 0.1. 2 nm RMS.

According to FIG. 5A, in the graphs represented by solid lines, black circles (●), and white triangles (Δ), the reflectance peak is in the vicinity of 130 to 135 mm.
The solid line in the graph indicates the reflectance calculated on the assumption that the density of the molybdenum layer and the silicon layer constituting the multilayer film is the same as that in the solid state, and the reflectance peak. The value (peak reflectance) is 71.0%. The black circles (●) indicate the reflectance calculated by setting the density of the silicon layer to 2.5 times that of the solid state, and the peak reflectance is 59.5%. In practice, it is considered that the silicon layer in the multilayer film does not have such a density. However, the effect when the multilayer film having a high reflectance and the multilayer film having a low reflectance are superimposed is effective. Such a multilayer film was assumed for verification. In the following description, a solid multilayer film is referred to as a highly reflective multilayer film, and a black circle (●) multilayer film is referred to as a low reflective multilayer film.

  The white triangle (Δ) indicates the reflectance calculated assuming a multilayer film in which 30 pairs of low-reflection multilayer films are formed on a substrate and 20 pairs of high-reflection multilayer films are formed thereon. . In this case, the peak reflectance was 70.2%. Compared to the case of the highly reflective multilayer film (solid line), the decrease in reflectance was 0.8%, and no significant decrease in reflectance was observed.

FIG. 5B is a graph showing a change in peak reflectance when the ratio of the number of layers of the high reflectance multilayer film is changed in the multilayer film of 50 pair layers.
The horizontal axis of FIG. 5B shows the film structure (number of pair layers of the low-reflectance multilayer film formed on the substrate) and (high reflectivity formed on the low-reflectance multilayer film). The ratio value ((high reflectivity) / (low reflectivity)) of the number of pair layers of the multilayer film is shown. The vertical axis | shaft of FIG. 5 (B) has shown the peak reflectance.

  According to FIG. 5B, when the number of layers of the high reflectance multilayer film is 10 pair layers (20%) or less, the value of the peak reflectance is low. However, when the number of layers of the high reflectivity multilayer film is 15 to 20 pair layers (30 to 40%) or more, a peak reflectivity close to that of the high reflectivity multilayer film is obtained.

  Therefore, also in the present invention, a multilayer film having a high reflectance formed by a magnetron sputtering method is formed on a multilayer film formed by an ion beam sputtering method so as to form 30 to 80% of the total number of layers. By forming the film, the reflectance of the entire multilayer film can be increased.

In the multilayer mirror of the present invention, molybdenum or a layer containing molybdenum may be formed by magnetron sputtering, and silicon or a layer containing silicon may be formed by ion beam sputtering.
In the present invention, molybdenum or a layer containing molybdenum (hereinafter simply referred to as a molybdenum layer) is formed on a silicon or silicon-containing layer (hereinafter simply referred to as a silicon layer) by magnetron sputtering. Since the interfacial diffusion layer formed at the interface becomes thin, it is possible to suppress a decrease in reflectance. In addition, since the silicon layer is formed by ion beam sputtering, a smoothing effect on the surface of the film can be obtained, so that even if the substrate surface is somewhat rough, a smooth and highly reflective multilayer film can be produced. .

  The reflective multilayer film forming method of the present invention is a reflective multilayer film forming method in which two or more kinds of substances having different refractive indexes are formed on a substrate surface, and each of the films constituting the multilayer film is formed. One of them is formed by ion beam sputtering, and the other film is formed by magnetron sputtering.

  The film forming apparatus of the present invention is an apparatus for forming a reflective multilayer film in which two or more kinds of substances having different refractive indexes are formed on a substrate surface, and includes an ion beam sputtering film forming apparatus and a magnetron sputtering process. A film device, and a device for forming a reflective multilayer film on the substrate surface can be formed by selecting and switching between the ion beam sputtering film forming device and the magnetron sputtering film forming device. It is characterized by being.

  An exposure apparatus according to the present invention is an exposure apparatus that forms a pattern by selectively irradiating a sensitive substrate with EUV light, and includes the above-described multilayer film reflecting mirror.

  According to the present invention, by using both the ion beam sputtering method and the magnetron sputtering method, a multilayer film reflecting mirror having a higher reflectance can be produced while reducing the surface roughness. Further, by using such a multilayer film reflecting mirror, the processing speed of the exposure apparatus can be improved.

BEST MODE FOR CARRYING OUT THE INVENTION

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view showing a reflective multilayer film according to a first embodiment of the present invention.
The substrate 103 shown in FIG. 1 is made of low thermal expansion glass, and the surface of the substrate 103 (the surface on the side where the reflective multilayer film 100 is formed) is polished to a surface roughness of 0.3 nm RMS with a period of 1 μm or less. .

On the surface of the substrate 103, a Mo / Si multilayer film (deep layer multilayer film) 101 made of molybdenum and silicon is formed in 30 pairs by ion beam sputtering. The periodic length (thickness of a pair layer of a molybdenum layer and a silicon layer) d ₁₀₁ of the deep multilayer film ₁₀₁ is about 7 nm. The surface roughness of the deep layer side multilayer film 101 is reduced to 0.15 nm RMS due to the surface smoothing effect obtained by forming the deep layer side multilayer film 101 by ion beam sputtering.

  On the surface of the deep-layer-side multilayer film 101, 20 pairs of Mo / Si multilayer films (surface-layer-side multilayer films) 102 are formed by low-pressure discharge rotary magnet cathode sputtering, which is a kind of magnetron sputtering. In the following description, the combination of the deep-side multilayer film 101 and the surface-layer multilayer film 102 is referred to as a reflective multilayer film 100.

  The reflectance of the reflective multilayer film 100 is dominated by the contribution of the portion closer to the reflective surface (the surface layer-side multilayer film 102). In this embodiment, the reflectance of the reflective multilayer film 100 is increased by forming the surface-layer-side multilayer film 102 by magnetron sputtering (low-pressure discharge rotary magnet cathode sputtering) that provides a high reflectance. In addition, the reflective multilayer film 100 has a high reflectivity because the surface roughness is reduced to 0.15 nm RMS or less due to the surface smoothing effect when the deep multilayer film 101 is formed by ion beam sputtering. can get.

  In this embodiment, the deep-layer-side multilayer film 101 formed by ion beam sputtering is a 30-pair layer, and the surface-layer multilayer film 102 formed by magnetron sputtering is a 20-pair layer. The number is not limited to this. However, the total number of pair layers of the deep-side multilayer film 101 and the surface-layer multilayer film 102 is preferably 60 pair layers or less. More preferably, the total number of pair layers is 50 pair layers or less. This is because, as the number of pair layers increases, the total film thickness of the multilayer film increases, and therefore an error in the relative film thickness distribution that occurs during film formation (the amount of deviation from the optimum film thickness distribution) accumulates. This is because the absolute amount of film thickness distribution error of the entire multilayer film increases. However, the film thickness distribution of the multilayer film can be strictly controlled, and when the film thickness distribution error of the entire multilayer film is sufficiently small, the number of pair layers can be freely selected.

  When the number of pair layers of the surface layer side multilayer film 102 formed by magnetron sputtering is larger than 40 pair layers, the entire reflection multilayer film 100 of the deep layer multilayer film 101 formed by ion beam sputtering is used. Almost no contribution to reflectivity. Therefore, it is not necessary to limit the period length of the deep-side multilayer film 101 formed by the ion beam sputtering method to 7 nm. In this case, the deep layer side multilayer film 101 contributes only to improving the surface roughness of the substrate.

FIG. 2 is a sectional view showing a reflective multilayer film according to the second embodiment of the present invention.
The substrate 203 shown in FIG. 2 is made of low thermal expansion glass, and the surface of the substrate 203 (the surface on the side where the reflective multilayer film 206 is formed) is polished to a surface roughness of 0.3 nm RMS with a period of 1 μm or less. .

On the surface of the substrate 203, 50 pairs of reflective multilayer films 206 are formed. The periodic length d ₂₀₆ of the reflective multilayer film 206 is about 7 nm. The molybdenum layer 205 of the reflective multilayer film 206 is formed by a low pressure discharge magnet cathode sputtering method which is a kind of magnetron sputtering method, and the silicon layer 204 is formed by an ion beam sputtering method.

The surface roughness is reduced by forming the silicon layer 204 by ion beam sputtering. For example, the surface roughness when a 30-pair layer is formed is reduced to 1.5 nm RMS.
On the other hand, since the molybdenum layer 205 is formed by magnetron sputtering (low pressure discharge magnet cathode sputtering), the interface diffusion layer at the interface where the molybdenum layer 205 is formed on the silicon layer 204 is thin.

  According to this example, in the 20 pair layers on the surface layer side, the roughness of the interface between the silicon layer 204 and the molybdenum layer 205 is as small as 1.5 nm RMS or less, and the interface diffusion layer is thin. High reflectivity can be obtained.

  In Example 1 and Example 2 described above, the substrate (reference numeral 103 in FIG. 1 and reference numeral 203 in FIG. 2) is made of low thermal expansion glass, but the material of the substrate is not limited to this. As a material for the substrate, quartz, silicon, or metal can be used in addition to glass.

  In Example 1 and Example 2 described above, a multilayer film made of molybdenum and silicon is used, but the material constituting the multilayer film is not limited to this. As a material constituting the multilayer film, for example, ruthenium (Ru), beryllium (Be), or an alloy or compound containing these metals can be used. The multilayer film may have a structure in which three or more kinds of substances are periodically stacked.

Furthermore, in Example 1 and Example 2 described above, a material such as carbon tetraboride (B ₄ C), molybdenum carbide (Mo ₂ C), or silicon carbide (SiC) is formed between the layers of the multilayer film. It is also possible to adopt a structure in which the layers are sandwiched as diffusion preventing layers. Further, a protective layer containing ruthenium or the like may be formed on the outermost surface of the multilayer film in order to prevent a decrease in reflectance due to oxidation.

FIG. 3 is a diagram showing a schematic configuration of an apparatus for forming a reflective multilayer film.
The film forming apparatus shown in FIG. 3 includes a magnetron sputtering film forming apparatus 401 and an ion beam sputtering film forming apparatus 402 in a vacuum chamber 407 evacuated. Thus, both film formation by ion beam sputtering and film formation by magnetron sputtering (low-pressure discharge magnet cathode sputtering) can be performed in one vacuum chamber 407.

  A substrate holder 416 is disposed in the upper left portion of the vacuum chamber 407 in the drawing. The substrate holder 416 includes a rotation drive mechanism (not shown) and can rotate around the rotation axis AX while holding the reflector substrate 415. In the vicinity of the substrate 415, a film thickness distribution correction plate 417 and a substrate shutter 418 are arranged in this order from the substrate 415 side.

  The substrate shutter 418 is closed when the film forming operation is not performed. The film thickness distribution correction plate 417 has an opening, and controls the aperture ratio of the film thickness distribution correction plate 417 to adjust the amount of film formation particles (reference numerals 411b and 413b in the figure) reaching the substrate 415. Thus, the film thickness of the film formed on the substrate 415 is controlled.

  The substrate holder 416 is movable while holding the substrate 415. When film formation by ion beam sputtering is performed, the substrate holder 416 has a surface (film formation surface) on which a multilayer film of the substrate 415 is formed on the ion beam sputtering film formation apparatus 402 as shown in FIG. It is fixed in the posture that turned. When performing film formation by magnetron sputtering, the substrate holder 416 has a posture in which the film formation surface of the substrate 415 faces the magnetron sputtering film formation apparatus 401 (the position of the substrate 415 at this time is indicated by reference numeral 415 ′). ). At this time, the film thickness distribution correction plate 417 and the substrate shutter 418 also move to positions 417 ′ and 418 ′ in the drawing, respectively.

The ion beam sputtering film forming apparatus 402 includes an ion source 408, a target shutter 410, a target holder 411, and the like.
When film formation is performed by ion beam sputtering, the substrate 415, the substrate holder 416, and the like are fixed at the positions in the drawing, and the target shutter 410 and the substrate shutter 418 are opened.

Then, the ion beam 408 b emitted from the ion source 408 is irradiated to the target material 411 a attached on the target holder 411. The target material 411a is sputtered by the ion beam 408b. The spattered scattered material (film formation particles 411 b) is deposited on the substrate 415 through the film thickness distribution control plate 417. The operating gas at this time is argon, and the gas pressure is about 0.01 Pa.
When the film formation is completed, both the target shutter 410 and the substrate shutter 418 are closed. This prevents unnecessary substances from adhering to the target material 411a and the substrate 415.

The magnetron sputtering film forming apparatus 401 includes a rotary magnet cathode 412, a target material 413, a target shutter 414, and the like.
When performing film formation by magnetron sputtering, first, the substrate holder 416 is moved to move the substrate 415 to the position of 415 ′ (in the following description, reference numeral 415 ′ of the position to which the substrate 415 and the like are moved). ). Then, the target shutter 414 and the substrate shutter 418 ′ are opened.

When a voltage is applied to the rotary magnet cathode 412, plasma is generated in the vicinity of the target material 413. The target material 413 is sputtered by this plasma, and the spattered scattered material (film-forming particles 413b) is deposited on the substrate 415 'through the film thickness distribution control plate 417'. At this time, the operating gas introduced into the film forming apparatus 401 is xenon, and the gas pressure is about 0.1 Pa. By maintaining the gas pressure of the operating gas at about 0.1 Pa, the film-forming particles 413b can reach the substrate 415 ′ with almost no collision with the atmospheric gas (operating gas).
When the film formation is completed, both the target shutter 414 and the substrate shutter 418 ′ are closed.

When the Mo / Si reflective multilayer film of Example 2 is formed using the film forming apparatus of this example, a molybdenum plate is used as the target material 413 in the magnetron sputtering film forming apparatus 401, and ion beam sputtering is performed. A silicon plate is used as the target material 411 a in the film device 402. Then, the molybdenum layer is formed by the magnetron sputter film forming apparatus 401, and the silicon layer is formed by the ion beam sputter film forming apparatus 402, so that a 50 pair Mo / Si reflective multilayer film is formed on the substrate 415. Is deposited.
In addition, what is necessary is just to make it the structure which can replace | exchange the target material 413 and the target material 411a suitably, when forming Mo / Si reflective multilayer film of Example 1 into a film.

  In this embodiment, a film forming apparatus based on a low-pressure discharge rotary magnet cathode sputtering method is used as the film forming apparatus 401, but other magnetron sputtering film forming apparatuses may be used.

In this example, only molybdenum and silicon are used as the multilayer film material, but the scope of the present invention is not limited to this, and carbon tetraboride (B ₄ C), molybdenum carbide (MoC), Other materials such as silicon carbide (SiC) or ruthenium (Ru) may be used. Moreover, these substances may be used not only in the periodic structure of the multilayer film, but also only in the outermost surface or a layer near the surface.

FIG. 4 is a diagram showing a schematic configuration of an EUV exposure apparatus (four-projection system) according to an embodiment of the present invention.
In the EUV exposure apparatus shown in FIG. 4, the entire optical path is kept in a vacuum. The EUV exposure apparatus shown in FIG. 4 includes an illumination system IL including a light source. EUV light radiated from the illumination system IL (generally, the wavelength is 5 to 20 nm, specifically, EUV light having a wavelength of 13 nm or 11 nm is used) is reflected by the folding mirror 301 and irradiated onto the reticle 302. The

  The reticle 302 has a required processing on the back surface (the surface opposite to the surface on which the pattern is formed), and is chucked and held by a chuck 303 a fixed to the reticle stage 303. The reticle stage 303 has a stroke of 100 mm or more in the scanning direction, has a minute stroke in a direction perpendicular to the scanning direction in the reticle surface, and also has a minute stroke in the optical axis direction. The scanning direction of the reticle stage 303 and the position in the direction orthogonal thereto are monitored with high accuracy by a laser interferometer (not shown), and the optical axis direction is a reticle focus sensor comprising a reticle focus light transmission system 304 and a reticle focus light reception system 305. Is being monitored.

  The EUV light reflected by the reticle 302 enters the lower optical barrel 314 in the drawing. This EUV light includes information on a circuit pattern drawn on the reticle 302. The reticle 302 is formed with a multilayer film (for example, molybdenum (Mo) / silicon (Si) or molybdenum (Mo) / beryllium (Be)) that reflects EUV light, and an absorption layer (for example, nickel) is formed on the multilayer film. Patterning is performed with or without (Ni) or aluminum (Al).

  In the optical barrel 314, four mirrors 306, 307, 308 and 309 are installed. These mirrors 306, 307, 308 and 309 are the multilayer mirrors of the present invention.

  The EUV light that has entered the optical barrel 314 is reflected by the first mirror 306, is then sequentially reflected by the second mirror 307, the third mirror 308, and the fourth mirror 309, and finally with respect to the wafer 310. Incident vertically. The reduction magnification of the projection system is, for example, 1/4 or 1/5. In this figure, four mirrors are used. A. To increase (Numerical Aperture), it is effective to use 6 or 8 mirrors. An alignment off-axis microscope 315 is disposed in the vicinity of the lens barrel 314.

  The wafer 310 is chucked and held on a chuck 311 a fixed to the wafer stage 311. The wafer stage 311 is installed so as to be orthogonal to the optical axis, and can move freely in a plane orthogonal to the optical axis. The stroke of the wafer stage 311 is, for example, 300 to 400 mm. The wafer stage 311 can be moved by a minute stroke also in the optical axis direction. The position of the wafer stage 311 in the optical axis direction is monitored by a wafer focus sensor including a wafer autofocus light transmission system 312 and a wafer autofocus light reception system 313. The position of the wafer stage 311 in the plane orthogonal to the optical axis is monitored with high accuracy by a laser interferometer (not shown). In the exposure operation, reticle stage 303 and wafer stage 311 have the same speed ratio as the reduction magnification of the projection system, for example, (moving speed of reticle stage 303) :( moving speed of wafer stage 311) is 4: 1 or 5: 1. Are synchronously scanned.

  In this embodiment, the multilayer mirror of the present invention is used as the four mirrors 306, 307, 308, and 309 in the optical barrel 314. However, the mirror, the folding mirror 301, the reticle 302, etc. included in the light source are used. Can also be used.

It is sectional drawing which shows the reflective multilayer film which concerns on the 1st Example of this invention. It is sectional drawing which shows the reflective multilayer film which concerns on the 2nd Example of this invention. It is a figure which shows schematic structure of the apparatus which forms a reflective multilayer film. It is a figure which shows schematic structure of the EUV exposure apparatus (4 sheet projection system) which concerns on one Embodiment of this invention. (A) It is a graph which shows the calculated value of the normal incidence reflectance with respect to EUV light of the Mo / Si multilayer-film reflective mirror by which the multilayer film with a high reflectance and the multilayer film with a low reflectance were laminated | stacked. (B) It is a graph which shows the change of the peak reflectance at the time of changing the ratio of the number of layers of a high reflectance multilayer film in a multilayer film of 50 pair layers.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Reflective multilayer film 101 Deep layer multilayer film 102 Surface layer multilayer film 103 Substrate 203 Substrate 204 Silicon layer 205 Molybdenum layer 206 Reflective multilayer film 401 Magnetron sputter deposition apparatus 402 Ion beam sputtering deposition apparatus 407 Vacuum chamber 408 Ion source 408b Ion beam 410 Target shutter 411 Target holder 411a Target material 411b Film formation particle 412 Rotary magnet cathode 413 Target material 413b Film formation particle 414 Target shutter 415 Reflector substrate 416 Substrate holder 417 Film thickness distribution correction plate 418 Substrate shutter IL illumination system 301 Folding mirror 302 Reticle 303 Reticle stage 303a Chuck 304 Reticle focus light transmission system 305 Reticle focus receiver Systems 306,307,308,309 mirror 310 wafer 311 wafer stage 311a chuck 312 wafers autofocus light transmitting system 313 wafer autofocus receiving system 314 barrel 315 off-axis microscope

Claims (8)

A multilayer film reflector in which a multilayer film formed by laminating two or more substances having different refractive indexes on a substrate surface is formed,
A multilayer film reflecting mirror characterized in that some of the films constituting the multilayer film are formed by ion beam sputtering, and the other films are formed by magnetron sputtering.   2. The multilayer film reflector according to claim 1, wherein the two or more kinds of substances are molybdenum or a substance containing molybdenum and silicon or a substance containing silicon.   A deep multilayer film closer to the substrate is formed by ion beam sputtering, and a surface multilayer film closer to the surface (optical functional surface) is formed by magnetron sputtering. The multilayer-film reflective mirror according to claim 1 or 2. The total number of layers of the multilayer film formed by ion beam sputtering and magnetron sputtering is about 40 to 60 layer pairs,
The multilayer reflector according to any one of claims 1 to 3, wherein a layer corresponding to 30 to 80% of the total number of layers of the multilayer film is formed by a magnetron sputtering method.   3. The multilayer reflector according to claim 1, wherein the molybdenum or a layer containing molybdenum is formed by a magnetron sputtering method, and the silicon or a layer containing silicon is formed by an ion beam sputtering method. . A method for forming a reflective multilayer film in which two or more kinds of substances having different refractive indexes are formed on a substrate surface,
A method for forming a reflective multilayer film, wherein one of the films constituting the multilayer film is formed by ion beam sputtering, and the other film is formed by magnetron sputtering. An apparatus for forming a reflective multilayer film in which two or more substances having different refractive indexes are formed on a substrate surface,
An ion beam sputter deposition apparatus;
A magnetron sputter deposition system;
With
An apparatus for forming a reflective multilayer film on the surface of the substrate can be formed while selecting and switching between the ion beam sputtering film forming apparatus and the magnetron sputtering film forming apparatus. Membrane device. An exposure apparatus for selectively irradiating EUV light onto a sensitive substrate to form a pattern,
An exposure apparatus comprising the multilayer film reflecting mirror according to claim 1.

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