JP2002222764A - Substrate with multilayer film, reflection mask blank for exposure, reflection mask for exposure, method of manufacturing it and method of manufacturing semiconductor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reflection mask for exposure which can make a transfer of a pattern in a lithography with high precision and is applicable also to EUV light with the very high flatness-surface of a multilayer film. SOLUTION: A stress correcting film 15 is formed for correcting a warpage, which is formed by a warpage in a substrate 11 and a stress in a multilayer film 12 and is formed in the surface of the film 12. The very high flatness- surface of the film 12 is obtained by correcting the warpage. A mask blank having this very high flatness-surface of the film 12 is manufactured and moreover, this mask blank is dry-etched, whereby a reflection type mask for exposure applicable also to EUV light is manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate with a multilayer film, a reflective mask blank for exposure, a reflective mask for exposure, a method for manufacturing the same, and a method for manufacturing semiconductors, which is used for controlling light used in semiconductor manufacturing and the like. About the method. The EUV (Extreme Ultra Vi) described in the present invention is used.
Olet) light refers to light in a wavelength band of a soft X-ray region or a vacuum ultraviolet region, and specifically has a wavelength of 0.2 to 100 nm.
It is about light.

[0002]

2. Description of the Related Art Conventionally, in the semiconductor industry, a photolithography method using visible light or ultraviolet light has been used as a technique for transferring a fine pattern necessary for forming an integrated circuit having a fine pattern on a Si substrate or the like. Have been. But,
While miniaturization of semiconductor devices is accelerating, shortening the wavelength of conventional light exposure is approaching the exposure limit. In the case of light exposure, the resolution limit of the pattern is said to be の of the exposure wavelength, and even if an F ₂ laser (157 nm) is used, the limit is expected to be about 70 nm. So as 70nm after exposure technique, F ₂ laser from a shorter wavelength of EUV light (1
Promising is EUV lithography (hereinafter, referred to as “EUVL”), which is an exposure technique using 3 nm).

The principle of EUVL image formation is the same as that of photolithography. However, since EUV light absorbs a large amount of all substances and has a refractive index close to 1, refractive optical systems such as light exposure cannot be used. , All use a reflective optical system. As a mask used at that time, a transmission type mask using a membrane has been proposed.
There is a problem that the exposure time becomes long because the membrane absorbs a large amount of UV light, and the throughput cannot be secured. Therefore, at present, a reflective mask for exposure is generally used.

For example, JP-B-7-27198 and JP-A-8-213303 provide a reflective layer having a multilayer structure on a substrate, and an absorber for absorbing soft X-rays or vacuum ultraviolet rays is provided on the reflective layer. A reflective mask for exposure provided in a pattern is disclosed. FIG. 3 is a schematic diagram showing an example of such a conventional reflective mask for exposure and a reflective mask for exposure. In the reflective mask blank for exposure shown in FIG. 3A, a reflective film 22 having a multilayer structure is formed on a substrate 21, an etching stopper layer 23 is formed on the reflective film 22, and an etching stopper 23 is formed.
It has a structure in which an absorption layer 24 is formed thereon. A pattern is formed on the absorption layer 24 of the exposure reflective mask blank, and the unnecessary etching stopper 23 on the multilayer film is removed to manufacture the exposure reflective mask shown in FIG. Soft X-rays and the like incident on the exposure reflective mask are reflected by the reflection film 22 and absorbed at the portion where the pattern of the absorber 24 is formed without being reflected. As a result, a pattern can be formed with a high contrast between the reflection part and the absorption part.

[0005]

However, in the reflective mask for exposure in which the multilayer film 22 is formed on the substrate 21 as described above, the film density of each layer of the multilayer film 22 must be reduced in order to obtain a high reflectance. Need to be higher. Then, the multilayer film 22 necessarily has a high compressive stress. Due to the high compressive stress, the substrate 21 is largely warped (deformed) to a convex surface as shown in FIG. As a result, the surface of the multilayer film 22, which is the reflection surface of the EUV light, is also warped. For example, when compressive stress of about 200 MPa is applied to a 0.3 μm-thick multilayer film 22 on a 6-inch square, 6.35 mm-thick quartz glass substrate, warpage (deformation) of about 500 nm in an area of 140 × 140 mm. Will happen.

As described above, in the prior art, the transfer accuracy is degraded (positional displacement) at the time of transferring a pattern to a wafer due to the warpage of the surface of the multilayer film 22, and high-precision transfer cannot be performed. was there. To solve this problem, it is conceivable to reduce the stress of the multilayer film 22. However, this lowers the density of the film and causes a decrease in the reflectivity of EUV light, which is not preferable from a practical viewpoint. Furthermore, the warpage of the surface of the multilayer film 22 is affected not only by the deformation of the substrate 21 due to the compressive stress of the multilayer film 22 described above, but also by the warpage inherent to the substrate 21. Therefore, it is difficult to effectively correct the warpage of the surface of the multilayer film 22 simply by reducing the stress of the multilayer film 22.

The present invention has been made under the above-mentioned background, and is intended to reduce the warpage (deformation) of the multilayer film surface 22 formed by the stress of the multilayer film 22 and the warpage (deformation) of the substrate 21 itself. Multilayer film 2 with corrected and high flatness
It is an object of the present invention to provide a substrate with a multilayer film, a reflective mask blank for exposure, a reflective mask for exposure, and the like, which have two surfaces and are applicable in a wavelength range from visible light to EUV light.

[0008]

According to a first aspect of the present invention, a reflective type for EUV exposure has a multilayer film on a substrate which reflects EUV light, and a light absorbing layer on the multilayer film for absorbing the EUV light. A mask blank, wherein the flatness of the surface of the multilayer film is not more than 100 nm.

Here, the flatness described in the present invention is TI
R (Total Indicated Readin)
The value representing the surface warpage (deformation amount) represented by g), and is defined as follows. That is, in FIG.
A plane determined by the least squares method based on 1 is a focal plane 32, and then the highest position A of the substrate surface 31 above the focal plane 32 with respect to the focal plane 32 and below the focal plane 32 The absolute value of the difference in height between the lowest position B on the substrate surface 31 was defined as flatness. Therefore, the flatness is always a positive number. In the present invention, 140 × 1
The measured value within the area of 40 mm is defined as flatness. For example, 140 × 140 mm at the center of a 6-inch substrate
Are the measured values in the area of.

According to a second aspect of the present invention, there is provided a reflective mask blank for EUV exposure, comprising a multilayer film on a substrate for reflecting EUV light, and a light absorbing layer on the multilayer film for absorbing the EUV light, A reflective mask blank for EUV exposure, comprising a stress correction film for correcting a warpage of the substrate and a warpage of the surface of the multilayer film formed by a stress of the multilayer film.

According to a third invention, there is provided a reflective mask blank for EUV exposure according to the second invention, wherein the stress correction film having a tensile stress is provided between the substrate and the multilayer film. is there.

A fourth invention is the reflective mask blank for EUV exposure according to the second invention, wherein the stress compensation film having a compressive stress is provided on the back surface of the substrate.

A fifth invention is the reflective mask blank for EUV exposure according to any one of the second to fourth inventions, wherein the stress compensation film is a material containing Ta.

A sixth aspect of the present invention is the reflective mask blank for EUV exposure according to the fifth aspect, wherein the stress correction film is made of a material containing Ta as a main component and containing at least B.

According to a seventh aspect of the present invention, there is provided a reflective mask for EUV exposure manufactured using the reflective mask blank for EUV exposure according to any one of the first to sixth aspects.

An eighth invention is a method of manufacturing a reflective mask for EUV exposure, which is manufactured using the reflective mask blank for EUV exposure according to any one of the first to sixth inventions. .

A ninth invention is directed to the EU described in the seventh invention.
A method for manufacturing a semiconductor, comprising transferring a pattern onto a substrate using a reflection mask for V exposure.

A tenth aspect of the present invention is a substrate with a multilayer film having a multilayer film reflecting EUV light on the substrate, wherein the flatness of the surface of the multilayer film is 100 nm or less. It is.

An eleventh invention is directed to a substrate with a multilayer film having a multilayer film reflecting EUV light on the substrate, wherein a surface of the multilayer film formed by warpage of the substrate and stress of the multilayer film is provided. A substrate with a multilayer film, comprising a stress correction film for correcting warpage. The substrate with the multilayer film is a reflective mask blank for EUV exposure, EU
It can be used for the production of a reflection mask for V exposure, an EUV reflection mirror, and the like.

According to a twelfth aspect, there is provided an EUV reflecting mirror manufactured using the substrate with a multilayer film according to the tenth or eleventh aspect.

According to a thirteenth aspect of the present invention, there is provided an exposure reflective mask blank having a multilayer film for reflecting light on a substrate and having a light absorbing layer for absorbing the light on the multilayer film. A reflective mask blank for exposure, wherein the flatness of the surface is 100 nm or less.

According to a fourteenth aspect, a substrate, a multilayer film formed on the substrate and reflecting light, a light absorbing layer formed on the multilayer film and absorbing the light, and a stress correction film are provided. An exposure reflective mask blank, comprising: the stress correction film, wherein the stress correction film corrects a warp generated on a multilayer film surface when the stress correction film is not formed. is there.

According to a fifteenth aspect, there is provided an exposure reflective mask manufactured using the exposure reflective mask blank according to the thirteenth or fourteenth aspect.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 and 2 show a reflection mask for exposure according to Embodiments 1 and 2 of the present invention (hereinafter, the reflection mask for exposure applicable to EUV light is “EUV mask”,
The reflective mask blank for exposure applicable to EUV light is described as "EUV mask blank". FIG. 6 is a flow chart showing an outline of the production of FIG. 6, and FIG. 6 is a conceptual diagram in which a pattern is exposed and transferred onto, for example, a Si wafer substrate using the produced EUV mask.

(Embodiment 1) Hereinafter, the manufacture of an EUV mask according to an embodiment of the present invention and transfer of a pattern onto a semiconductor substrate by the EUV mask will be described with reference to FIGS. Manufacture of EUV masks,
And the pattern transfer onto the semiconductor substrate using the EUV mask includes (1) a substrate preparation step, (2) a stress correction film formation step on the substrate, (3) a multilayer film formation step on the substrate, (4) film forming process of etching stopper, (5) E
UV absorbing layer film forming step, (6) EB resist coating step,
(7) EB drawing step, (8) dry etching step,
(9) pattern transfer onto a semiconductor substrate using an EUV mask.

(1) Substrate preparation step. The substrate 11 is preferably a glass having a low coefficient of thermal expansion and having excellent smoothness, flatness, and resistance to a cleaning solution used for cleaning an EUV mask, and a glass having a low coefficient of thermal expansion, for example, SiO ₂ —TiO _2. Although a system glass or the like is used, the substrate is not limited to this, and a substrate made of crystallized glass, quartz glass, silicon, metal, or the like on which a β-quartz solid solution is precipitated can also be used. Examples of the metal substrate include an invar alloy (Fe
-Ni alloy) or the like can be used. The substrate 11 preferably has a smooth surface of 0.2 nmRms or less and a flatness of 100 nm or less in order to obtain high reflectance and transfer accuracy.

In the present invention, the unit R showing smoothness is used.
ms is root mean square roughness, which can be measured by an atomic force microscope (AFM). The specific measurement is performed, for example, within a range of 10 μm square, but it is preferable that the mask has the smoothness uniformly within the effective area of the mask. Here, in the case of a mask for EUV light exposure, the effective area of the mask may be, for example, a range of about 142 mm square as the effective area.

(2) Step of forming a stress compensation film on the substrate. In order to achieve the object of the present invention described above, the present inventors:
As a result of intensive studies, the stress correction film 15 for correcting the warpage (deformation) of the substrate 11 formed by the stress or the like of the multilayer film 12 has a high stress by forming it under the conditions described later. It has been found that even when the multilayer film 12 is formed, the warpage (deformation) of the substrate 11 can be corrected and the surface of the multilayer film can be kept flat.

In addition, it is preferred that the substrate 11
Even if its own warpage (deformation) is large, the stress compensation film 15
It has been found that by appropriately adjusting the stress value of the substrate 11, it is possible to correct the warpage of the surface of the multilayer film including the warpage (deformation) of the substrate 11 itself. That is, the warpage (deformation) of the multilayer film surface is the warpage (deformation) generated by the stress (normally, compressive stress) of the multilayer film 12.
And the warpage inherent to the substrate 11 itself (including the warpage generated during the manufacture of the substrate).
If this is the case, the inventor has conceived that a stress correction film 15 that corrects the warpage of the substrate 11 and the warpage of the multilayer film surface formed by the stress of the multilayer film 12 should be formed. The stress compensation film can be formed between the substrate and the multilayer film or on the back surface of the substrate (the surface on which the multilayer film is not formed).

As a result, by correcting the warpage of the surface of the multilayer film and increasing the flatness, for example, in the EUV light mask of the present invention, the positional deviation at the time of transferring the pattern to the wafer can be suppressed, and the accuracy can be improved. . Specifically, when the flatness of the multilayer film surface is set to 100 nm, the displacement in transfer becomes about 2.2 nm, and when it is set to 50 nm, it can be suppressed to about 1.1 nm. It becomes possible.

The stress of the multilayer film can be calculated by measuring the warpage of the substrate before and after the formation of the multilayer film and calculating the difference between the warpages before and after the film formation. Here, the compressive stress has a minus sign, and the tensile stress has a plus sign. Also, the stress of the multilayer film depends on its material,
Since it can be predicted to some extent from the film formation conditions, the stress of the multilayer film can be predicted from data obtained experimentally and the like, and the stress and film thickness to be applied to the stress correction film can be determined. Further, monitoring may be performed as needed, and the stress and the film thickness applied to the stress correction film may be corrected as appropriate.

In the first embodiment, an embodiment in which the stress correction film is formed between the substrate and the multilayer film will be described. In a second embodiment to be described later, the stress correction film is formed on the substrate. An embodiment in which a film is formed on the back surface will be described.

If a substrate without warpage (deformation) can be used as the substrate 11, the stress correction film 15 may be formed with a stress and a film thickness that cancel the stress of the multilayer film 12. . Here, since the stress is generally represented by a value per unit thickness, the material of the stress correction film 15 and the film forming conditions are set so that the stress per unit thickness × the thickness of the film to be formed is balanced. The thickness may be determined.
In the first embodiment, since the stress correction film 15 is formed between the substrate 11 and the multilayer film 12, as shown in FIG.
The stress correction film 15 having the same magnitude as the stress of the multilayer film 12 and having the opposite direction may be formed.

On the other hand, there is a case where the substrate 11 which has been warped in advance is used. At this time, (a) the case where the direction of the warpage of the substrate 11 and the direction of the stress of the multilayer film 12 are the same,
(B) The direction of the warp of the substrate 11 may be opposite to the direction of the stress of the multilayer film 12 in some cases.

(A) Warp direction of substrate 11 and multilayer film 12
In this case, when the directions of the stresses of the
The total of the warpage (deformation) of 1 and the stress of the multilayer film 12 causes the multilayer film surface to warp. Therefore, the stress correction film 15 may be formed so as to cancel the sum of these stresses.

(B) The direction of warpage of the substrate 11 and the multilayer film 12
In the case where the directions of the stresses are reversed, the stresses of the multilayer film 12 can be reduced and canceled by the warpage (deformation) of the substrate 11 given in advance. Since the multilayer film 12 usually has a compressive stress, the substrate 11 on which the multilayer film 12 is formed is warped such that the side on which the multilayer film 12 is formed becomes convex. Therefore,
If the multilayer film 12 is formed on the substrate 11 having a warp in which the side on which the multilayer film 12 is formed is concave, the warpage of the substrate 11 and the warpage due to the stress of the multilayer film 12 are offset,
Warpage of the multilayer film surface can be reduced. Then, for the reduced warpage, a stress correction film 15 may be formed to cancel the warpage.

If the stress of the multilayer film 12 can be completely canceled by the warpage (deformation) of the substrate 11 given in advance, the flat multilayer film surface can be formed without forming the stress correction film 15. It is also possible to get. In order to prepare the warped substrate 11, for example, there is a method of processing the substrate 11 so as to have a desired surface (warpage) at the time of initial slicing of the substrate.

Here, a method for forming the stress correction film 15 will be described. Since the surface of the stress compensation film needs to be a smooth film, an amorphous material is preferable. Further, a material containing Ta as a main component is preferable. An amorphous material containing Ta as a main component is preferable. The smoothness of the surface of the stress correction film is preferably 0.2 nmRms or less, more preferably 0.15 nmRms or less. When a TaB film (a film containing Ta and B) is used as a film forming example of the stress correction film 15, it is preferable to form the film using a DC magnetron sputtering method at room temperature in an Ar gas atmosphere. The stress of the stress correction film 15 can be adjusted to a desired value by appropriately controlling the film forming method and the film forming conditions (sputter gas pressure, input power, film thickness, etc.).

For example, in the case of a TaB film, when the sputter gas pressure is changed under a constant input power, a compressive stress is exhibited on the low pressure side, the stress is decreased when the gas pressure is increased, and finally, the pressure becomes zero. When the pressure is increased, a tensile stress is exhibited, and the stress increases with the gas pressure. Thus, the stress varies according to the sputter gas pressure. Using this effect, the stress of the multilayer film 12 and the warpage of the substrate 11 can be canceled by using the stress of the stress correction film 15.
The stress value and direction of the stress correction film 15 may be adjusted by controlling the sputtering conditions (sputter gas pressure, input power, film thickness, etc.). Here, in the film containing Ta and B,
B is preferably 10 to 30 at%. Also, Ta
And a film containing B and N, when N is 5 to 30 at% and the components other than N are 100 at%, B is 10 at%.
It is preferably about 30 at%.

The material of the stress compensation film 15 is TaB
As another example, a material containing Si as a main component can be used. Specifically, it is a simple substance of Si or a substance obtained by doping an additive to Si, and examples of the additive include N and O. The material containing Si as a main component is preferably in an amorphous state, and preferably has semiconductor properties. In the case where the stress correction film is formed between the substrate and the multilayer film or on the back surface of the substrate (the surface on which the multilayer film is not formed), as described later in Embodiment 2, 11 is a stress compensation film 1 made of a conductive material on the back surface.
If the EUV mask 5 is provided, when handling the EUV mask blank and EUV mask, the substrate 11
This is because, when there is a request to chuck the back surface with an electrostatic chuck, the chucking property is improved.

Further, as a material of the stress compensation film 15, Cr
Can be used. As the material containing Cr, for example, a material containing Cr and N can be used. In the material containing Cr and N, the ratio of N is preferably 5 to 35 at%, and more preferably 10 to 25 at%. Further, it is also preferable that the material containing Cr and N contains O and / or C. These Cr-containing materials are excellent in smoothness and washing resistance, and have good stress controllability. The material containing Cr is D
The film can be formed by a C sputtering method or the like. that's all,
Examples of the stress correction film 15 include a TaB film, a Si-based film, and a Cr film.
Although a system film was mentioned, the film is not limited thereto, and any film may be used as long as it is a smooth film that can easily control stress.
Si, TaSiN, WN, etc. can also be used.

(3) Step of forming a multilayer film on a substrate. As the multilayer film 12, a multilayer film composed of Mo and Si is frequently used. As materials capable of obtaining a high reflectance in a specific wavelength region, Ru / Si, Mo / Be, and Mo compound / Si are used.
Compound, Si / Nb periodic multilayer, Si / Mo / Ru periodic multilayer, Si / Mo / Ru / Mo periodic multilayer, and Si
A / Ru / Mo / Ru periodic multilayer film may be used. However,
The optimum film thickness depends on the material. In the case of a multilayer film composed of Mo and Si, a DC film is first formed by a DC magnetron sputtering method using an Si target under an Ar gas atmosphere, and then an Mo film is formed using an Mo target under an Ar gas atmosphere. And this is defined as one cycle, and 30
After stacking up to 60 cycles, preferably 40 cycles,
An i film is formed. Here, an example of the stress of the multilayer film 12 was −500 MPa at a thickness of 0.2 μm. By this step, a substrate with a multilayer film is obtained.

(4) Step of forming an etching stopper. SiO ₂ is often used as a material for the etching stopper film 13, but depending on the conditions for etching the absorption layer 13, a material having high etching resistance, such as Al ₂ O ₃ or Cr, may be used.
N or the like may be used. When SiO ₂ is used, the SiO ₂ target is formed on the substrate with the multilayer film by an RF magnetron sputtering method using an SiO ₂ target under an Ar gas atmosphere.
_It is preferable to form _two films.

(5) Step of forming a EUV absorption layer. The material of the EUV absorption layer 13 is a material containing Ta as a main component. A material containing Ta as a main component and containing at least B. Ta
A material with an amorphous structure whose main component is. A material having an amorphous structure containing Ta as a main component and containing at least B.
(For example, a material having an amorphous structure containing about 25% of B expressed by Ta ₄ B) A material containing Ta, B, and N (for example, containing about 15% of B as a main component and about 10% of N) Material with amorphous structure) Cr as main component, N, O,
A material containing at least one component selected from C.
(For example, CrN, a material obtained by adding O and C to CrN) and the like have been found to be preferable. However, it is not limited to this, and TaSi, TaSiN, TaGe, TaGeN, W
N, Cr, TiN, etc. can also be used.

In the case where a TaB compound thin film is used as the material of the EUV absorption layer 13, it is preferable to form a Ta ₄ B film by a DC magnetron sputtering method using a Ta ₄ B target in an Ar gas atmosphere. On this occasion,
It is preferable that the stress of the EUV absorption layer 13 be set to 50 MPa or less by optimizing the sputtering conditions (gas pressure, DC power, etc.). Through this step, an EUV mask blank is obtained.

The EUV mask blank of the present invention and an EUV mask described later are characterized in that the stress correction film for correcting the warpage of the multilayer substrate is provided as described above. Here, the warpage of the multilayer film surface is mainly caused by the warpage of the substrate itself and the warpage caused by the stress of the multilayer film formed on the substrate. In the case of a structure having a layer, an etching stopper, and the like, the stress and the film thickness of the stress correction film may be determined so as to finally obtain a desired flatness in consideration of the stress of the intermediate layer and the like.

(6) EB resist coating step. An EUV mask can be manufactured by forming a pattern on the absorption layer of the obtained EUV mask blank. EB on the EUV mask blank obtained in step (5)
A resist is applied and baking is performed at 200 ° C.

(7) EB drawing step. 30k on EUV mask blank coated with EB resist
A resist pattern was created using an eV EB lithography machine.

(8) Dry etching step. Using the resist pattern as a mask, the EUV absorption layer 14 was dry-etched using chlorine at a substrate temperature of 20 ° C. using an ICP-RIE apparatus to form a pattern of the absorption layer. At this time, the underlying SiO ₂ film was removed using a diluted hydrofluoric acid solution. Further, the resist remaining on the absorption layer pattern was removed with hot concentrated sulfuric acid at 100 ° C. By this process, EU
A V mask is obtained.

Here, the method of forming a pattern on the absorption layer has been described by way of an example using an etching method, but the present invention is not limited to this. For example, a lift-off method can be used.

(9) Transferring a pattern onto a semiconductor substrate using an EUV mask. As shown in FIG. 6, EUV light (soft X-ray) obtained from a laser plasma X-ray source 41 is incident on the EUV mask 42, and the reflected light is passed through a reduction optical system 43 to, for example, a Si wafer substrate 44. Transfer to the top.

As the reduction optical system 43, an X-ray reflection mirror can be used.
The pattern reflected by 2 is usually reduced to about 1/4. For example, the transfer of the pattern to the Si wafer substrate 44 is as follows.
It can be performed by exposing a pattern to a resist layer formed on the Si substrate 44 and developing the pattern. When a wavelength band of 13 to 14 nm is used as the exposure wavelength, the transfer is usually performed such that the optical path is in a vacuum. 1
As a material of a multilayer film in a wavelength band of 3 to 14 nm,
A Mo / Si multilayer film having a peak wavelength in this wavelength band can be used. By using the EUV mask obtained in this embodiment to form a pattern on, for example, a Si wafer substrate, a semiconductor device such as a highly integrated LSI can be manufactured.

(Embodiment 2) Next, with reference to FIGS. 2 and 6, manufacturing of an EUV mask according to another embodiment of the present invention and transfer of a pattern onto a semiconductor substrate by the EUV mask will be described. . The manufacture of an EUV mask and the transfer of a pattern onto a semiconductor substrate using the EUV mask include (1) a substrate preparation step, (2) a stress correction film formation step on the back surface of the substrate (on which a multilayer film is not formed),
(3) a step of forming a multilayer film on a substrate, (4) a step of forming an etching stopper, (5) a step of forming an EUV absorption layer, (6) an EB resist coating step, (7) an EB drawing step, (8) A dry etching step, and (9) a step of transferring a pattern onto a semiconductor substrate using an EUV mask.

When this embodiment is compared with the first embodiment, “(2) Step of forming a stress correction film on the back surface of the substrate (the side on which no multilayer film is formed)” is different. explain.

(2) Step of forming a stress correction film on the back surface of the substrate. The multilayer film 12 usually has a compressive stress. Therefore, the substrate 11
When forming the stress correction film 16 on the back surface, if the substrate 11 is not substantially warped, the formed stress correction film 16 may cancel the warpage caused by the stress of the multilayer film 12. What is necessary is just to have a suitable stress and film thickness. Although the material is not particularly limited, as described above, a conductive semiconductor film or a metal film is effective and preferable for handling when an electrostatic chuck is used. Here, the force that the film gives to the warpage of the substrate is generally the product of the stress of the film material and the film thickness.
6, the product of the stress of the stress compensation film material 16 and the film thickness is determined by the warpage of the substrate 11 and the multilayer film 12.
May be determined so as to cancel the sum of the warpage due to the stress of the above. For example, the stress correction film 16 has a thickness of 0.28 μm.
In the case of a stress of -500 MPa at m, if the thickness is reduced to half of 0.14 μm, a material having a stress doubled at −1000 MPa is selected. If the substrate 11 itself has substantially no warp, the thickness of the multilayer film 12 and the thickness of the stress correction film 16 are made equal, and the stress of the same magnitude as the multilayer film 12 is applied to the stress correction film 1.
It is convenient to form a film so as to give the film No. 6 as well.

Back surface of substrate 11 (side on which no multilayer film is formed)
When a TaB film is formed as the stress correction film 16 on the top,
It is preferable to form a film at room temperature under an Ar gas atmosphere using a DC magnetron sputtering method. At this time, the thickness of the stress correction film 16 is the same as that of the multilayer film 12 to be formed, and the stress cancels the stress of the multilayer film 12.
The sputtering conditions are controlled so as to be approximately equal to the stress of No. 2. Here, in the TaB film, as described above, the stress can be easily varied by controlling the gas pressure and the DC power among the sputtering conditions. Can be controlled.

According to this embodiment, Embodiment-1
Thus, a substrate with a multilayer film, an EUV mask blank and an EUV mask having the same characteristics as those described above were obtained. By forming a pattern on, for example, a Si wafer substrate using the EUV mask obtained in the second embodiment in this way, a semiconductor device such as a highly integrated LSI can be manufactured.

In the present embodiment, an example in which the stress correction film 16 is formed on the back surface of the substrate 11 before the step of forming the multilayer film 12 has been described.
May be performed between each step after the film formation. For example, after forming the multilayer film 12, after forming the absorbing layer 14, or after forming a pattern on the absorbing layer 14.

(EUV reflection mirror of a substrate with a multilayer film,
Application to the etc.) The substrate with a multilayer film described in the present invention is an EU substrate.
It can be applied to V masks, EUV mask blanks, EUV reflection mirrors, and the like.

However, in the reflection mirror for EUV,
In many cases, a curved surface is required as a light reflection surface. Therefore, when the substrate with a multilayer film described in the present invention is applied, the magnitude and direction of the stress of the stress correction film may be adjusted to correct the warpage of the reflection surface to a desired curvature.

(Embodiment 1) A first embodiment of the present invention will be described with reference to FIG. As the glass substrate 11, low expansion SiO ₂ having an outer diameter of 6 inches square and a thickness of 6.3 mm
-TiO with ₂ glass substrate. The glass substrate 11 was mechanically polished to have a smooth surface of 0.2 nmRms or less and a flatness of 90 nm concave.

The stress compensation film 1 is formed on the surface of the glass substrate 11.
As No. 5, a TaB film (Ta: B = 75: 15 (atomic ratio)) was formed. The TaB film was formed at room temperature under an Ar gas pressure of 0.6 Pa using a DC magnetron sputtering method.
It was formed to a thickness of 0.28 μm. As a result, the stress of the stress correction film 15 has a tensile stress opposite to that of the multilayer film 12 so as to cancel the stress of the multilayer film 12, and
The stress value was +480 MPa, which was almost the same.

As the multilayer film 12, Mo and Si were laminated. First, a Si film was formed by a DC magnetron sputtering method using a Si target with an Ar gas of 0.1 Pa.
Then, using a Mo target, a 2.8 nm-thick Mo film was formed at an Ar gas pressure of 0.1 Pa.
After stacking forty cycles, the Si film is finally covered with 4n.
m was formed. Here, the stress of the multilayer film 12 is −5.
It was 00 MPa. The flatness of the substrate with a multilayer film obtained here was 40 nm.

Next, using an SiO ₂ target on the multilayer film 12 and using Ar gas as a sputtering gas,
The etching stopper 13 composed of the iO ₂ film is
A film was formed to a thickness of 0.05 μm by F magnetron sputtering. Here, the stress of the etching stopper 13 was -50 MPa.

Finally, a film containing Ta and B (Ta: B = 75: 15) is formed as an EUV absorbing layer 14 on the etching stopper 13 composed of the SiO ₂ film.
(Atomic ratio) was formed to a thickness of 0.1 μm by DC magnetron sputtering. At this time, the stress of the EUV absorption layer 14 was set to +50 MPa by controlling the sputtering conditions. As a result, an EUV mask blank having a feature that the flatness of the surface of the multilayer film was 50 nm was obtained.

Next, using this EUV mask blank, a 16 Gbit-D having a design rule of 0.07 μm was used.
An EUV mask having a pattern for RAM was manufactured by the method described below.

First, an EB is placed on the EUV mask blank.
The resist was coated, and a resist pattern was formed by EB drawing.

Using this resist pattern as a mask, T
aB absorption layer 14 is dry-etched using chlorine,
An absorption pattern was formed on the EUV mask blank. Etching stopper 1 composed of underlying SiO ₂ film
In No. 3, an EUV mask was manufactured by removing the resist remaining on the absorption pattern by removing with diluted hydrofluoric acid.

For the EUV mask produced above,
As a result of measuring the flatness of the multilayer film surface with an interferometer, 50
It was confirmed to have a high flatness of nm. Furthermore, as a result of performing exposure transfer in EUVL, it was confirmed that the EUVL had sufficiently high precision EUV reflection characteristics.

(Embodiment 2) Referring to FIG.
An example will be described. Example 1 as the substrate 11
A glass substrate having the same flatness as described above was used. A TaB film is formed as a stress correction film 16 on the back surface of the glass substrate 11 (the side on which the multilayer film is not formed). TaB film (however, T
a: B = 75: 15 (atomic ratio), using a DC magnetron sputtering method at room temperature and an Ar gas pressure of 0.2 Pa
Then, a film was formed to a thickness of 0.28 μm. At this time, the thickness of the stress correction film 16 is 0.28 μm, which is the same as that of the multilayer film 12 to be formed.
m, and the stress was −500 MPa in the same direction and the same magnitude so as to cancel out the stress of the multilayer film 12. The flatness of the substrate with a multilayer film obtained here is 90 nm.
Met.

On the surface of the glass substrate 11, a multilayer film 12 similar to that of the first embodiment is formed, and on the multilayer film, an etching stopper 13 composed of a SiO ₂ film similar to that of the first embodiment is formed. did. The same EUV absorption layer 14 containing Ta and B as in Example 1 was formed on the SiO ₂ . As a result, an EUV mask blank having a characteristic that the flatness of the multilayer film surface is 100 nm was obtained.

Using this EUV mask blank, an EUV mask was produced in the same manner as in Example 1. As a result of measuring the flatness of the multilayer film surface of the EUV mask manufactured above using an interferometer, it was confirmed that the EUV mask had a high flatness of 100 nm. Furthermore, as a result of performing exposure transfer in EUVL, it was confirmed that the EUVL had sufficiently high precision EUV reflection characteristics.

(Embodiment 3) Referring to FIG. 2, a third embodiment of the present invention will be described.
An example will be described. Example 1 as the substrate 11
The same glass substrate 11 was used. However, the glass substrate 11 has a smooth surface of 0.2 nm or less and a flatness of 500 nm convex by mechanical polishing.

A TaB film is formed as a stress correction film 16 on the back surface of the glass substrate 11 (on the side where no multilayer film is formed). The TaB film (Ta: B = 75: 15 (atomic ratio)) was formed to a thickness of 0.3 μm at room temperature under an Ar gas pressure of 0.15 Pa using a DC magnetron sputtering method. The thickness of the stress compensation film 16 is
−700 MPa is obtained so as to eliminate both the warpage (deformation) and the stress of the multilayer film 12.

On the surface of the glass substrate 11, a multilayer film 12 similar to that of Example 1 was formed. Here, the stress of the multilayer film 12 was -500 MPa. The flatness of the substrate with a multilayer film obtained here was 50 nm. Next, the multilayer film 12
An etching stopper 13 composed of the same SiO ₂ film as in Example 1 was formed thereon. Finally, the SiO
_{On the} etching stopper 13 composed of the _two films, the same EUV absorption layer 14 containing Ta and B as in Example 1 was formed. As a result, an EUV mask blank having a characteristic that the flatness of the multilayer film surface is 60 nm was obtained.

Using this EUV mask blank, an EUV mask was produced in the same manner as in Example 1. As a result of measuring the flatness of the multilayer film surface of the EUV mask manufactured as described above using an interferometer, it was confirmed that the EUV mask had a high flatness of 60 nm. Furthermore, as a result of performing exposure transfer in EUVL, it was confirmed that the EUVL had sufficiently high precision EUV reflection characteristics.

As is clear from the results described in Examples 1 to 3, according to the present invention, in the EUV mask blank and the substrate with a multilayer film, the flatness of the multilayer film surface is 1%.
EUV manufactured from this
If a mask is used, it is possible to perform high-precision pattern transfer with small displacement during pattern transfer. Further, according to the present invention, by forming the stress correction film, it is possible to correct the stress of the multilayer film and the warpage of the multilayer film surface formed by the warpage of the substrate itself, and a wide range from visible light to EUV light. A multilayer-coated substrate, a mask blank, a mask, and a multilayer mirror having a desired curvature, which can be applied in the wavelength region and have a multilayer surface with high flatness, can be obtained.

[0078]

As described above in detail, according to the present invention, the stress compensation film for compensating the warpage of the surface of the multilayer film formed by the warpage of the substrate and the stress of the multilayer film is formed. The present invention realizes a substrate with a multilayer film, a mask blank, a mask, and the like having a multilayer film surface with high flatness by correcting the stress of the film and the warpage of the multilayer film formed by the warpage of the substrate itself.

[Brief description of the drawings]

FIG. 1 is a manufacturing flow of a substrate with a multilayer film, a mask blank, and a mask according to Embodiment 1.

FIG. 2 is a flowchart of manufacturing a substrate with a multilayer film, a mask blank, and a mask according to the second embodiment.

FIG. 3 is a conceptual diagram (cross-sectional view) of a mask blank and a mask according to a conventional embodiment.

FIG. 4 is a conceptual diagram (cross-sectional view) of a mask according to a conventional embodiment.

FIG. 5 is a conceptual diagram for explaining the definition of flatness in the present invention.

FIG. 6 shows an example of using a mask according to the present invention to form an E
Conceptual diagram of pattern transfer by UV light

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Glass substrate 12 Multilayer film 13 Etching stopper 14 Absorption layer 15 Stress correction film 16 Stress correction film 21 Substrate 22 Multilayer film 23 Etching stopper 24 Absorption layer 31 Substrate surface 32 Focal plane 41 Laser plasma X-ray source 42 Mask 43 Reduction reflection optical system 44 wafer

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) G02B 5/28 G03F 1/16 A G03F 1/16 7/20 503 7/20 503 H01L 21/30 531M F term (reference) ) 2H042 AA15 AA25 DA08 DA12 DA15 DA22 DB02 DE00 2H048 CA05 CA13 CA17 CA24 CA29 FA05 FA09 FA18 FA22 FA24 GA04 GA11 GA24 GA33 GA61 2H095 BA01 BA10 BC24 BC26 2H097 CA15 GB00 LA10 5F046 GB01 GD05 GD10 GD16

Claims (15)

[Claims] 1. A reflective mask blank for EUV exposure, comprising a multilayer film for reflecting EUV light on a substrate, and a light absorbing layer for absorbing the EUV light on the multilayer film, wherein the surface of the multilayer film is A reflective mask blank for EUV exposure, wherein the flatness of the mask is 100 nm or less. 2. A reflective mask blank for EUV exposure, comprising a multilayer film on a substrate for reflecting EUV light, and a light absorbing layer on the multilayer film for absorbing the EUV light, wherein the substrate is warped. A reflective mask blank for EUV exposure, comprising: a stress correction film for correcting warpage of the surface of the multilayer film formed by the stress of the multilayer film. 3. The reflective mask blank for EUV exposure according to claim 2, wherein the stress correction film having a tensile stress is provided between the substrate and the multilayer film. 4. The reflective mask blank for EUV exposure according to claim 2, wherein the stress correction film having a compressive stress is provided on a back surface of the substrate. 5. The reflective mask blank for EUV exposure according to claim 2, wherein the stress correction film is made of a material containing Ta. 6. The stress compensation film according to claim 5, wherein the stress compensation film is a material containing Ta as a main component and containing at least B.
4. The reflective mask blank for EUV exposure according to 1. 7. The E according to claim 1, wherein
A reflective mask for EUV exposure, manufactured using a reflective mask blank for UV exposure. 8. The E according to claim 1, wherein
A method for manufacturing a reflective mask for EUV exposure, which is manufactured using a reflective mask blank for UV exposure. 9. A method for manufacturing a semiconductor, comprising: transferring a pattern onto a substrate using the reflective mask for EUV exposure according to claim 7. Description: 10. A substrate with a multilayer film having a multilayer film that reflects EUV light on the substrate, wherein the flatness of the surface of the multilayer film is 100 nm or less. 11. A substrate with a multilayer film having a multilayer film reflecting EUV light on the substrate, wherein the warpage of the surface of the multilayer film formed by the warpage of the substrate and the stress of the multilayer film is corrected. A substrate with a multilayer film, comprising a stress compensation film. 12. An EUV reflection mirror manufactured using the substrate with a multilayer film according to claim 10. 13. A multi-layer film for reflecting light on a substrate,
A reflective mask blank for exposure having a light absorbing layer for absorbing the light on the multilayer film, wherein the flatness of the surface of the multilayer film is 100 nm or less. 14. An exposure reflector comprising: a substrate; a multilayer film formed on the substrate to reflect light; a light absorbing layer formed on the multilayer film to absorb the light; and a stress correction film. A reflective mask blank for exposure, wherein the stress correction film corrects a warp generated on a multilayer film surface when the stress correction film is not formed. 15. An exposure reflective mask manufactured using the reflective mask blank for exposure according to claim 13. Description: