JP6864952B2 - Method for manufacturing a substrate with a conductive film, a substrate with a multilayer reflective film, a reflective mask blank, a reflective mask, and a semiconductor device. - Google Patents

Description

The present invention relates to a substrate with a conductive film, a substrate with a multilayer reflective film, a reflective mask blank, a reflective mask, and a method for manufacturing a semiconductor device for use in EUV lithography.

In recent years, in the semiconductor industry, with the increasing integration of semiconductor devices, a fine pattern exceeding the transfer limit of the conventional photolithography method using ultraviolet light has been required. In order to enable such fine pattern formation, EUV lithography, which is an exposure technique using extreme ultraviolet (hereinafter referred to as "EUV") light, is promising. Here, EUV light refers to light in the wavelength band of the soft X-ray region or the vacuum ultraviolet region, and specifically, light having a wavelength of about 0.2 to 100 nm. A reflective mask has been proposed as a transfer mask used in this EUV lithography. In such a reflective mask, a multilayer reflective film that reflects the exposure light is formed on the substrate, and an absorber film that absorbs the exposure light is formed in a pattern on the multilayer reflective film.

The reflective mask forms an absorbent film pattern from a substrate, a multi-layer reflective film formed on the substrate, and a reflective mask blank having an absorbent film formed on the multi-layer reflective film by a photolithography method or the like. Manufactured by

The multilayer reflective film and the absorber film are generally formed by using a film forming method such as sputtering. At the time of the film formation, the reflective mask blank substrate is supported by the supporting means in the film forming apparatus. An electrostatic chuck is used as a substrate supporting means. Therefore, in order to promote fixing of the substrate by the electrostatic chuck on the back surface of the insulating reflective mask blank substrate such as a glass substrate (the surface opposite to the surface on which the multilayer reflective film or the like is formed), A conductive film (back surface conductive film) is formed.

As an example of a substrate with a conductive film, Patent Document 1 describes a substrate with a conductive film used for manufacturing a reflective mask blank for EUV lithography, and the conductive film contains chromium (Cr) and nitrogen (N). The average concentration of N in the conductive film is 0.1 at% or more and less than 40 at%, at least the crystal state of the surface of the conductive film is amorphous, and the surface roughness (rms) of the conductive film is 0.5 nm. The conductive film is a gradient composition film in which the N concentration in the conductive film is changed along the thickness direction of the conductive film so that the N concentration on the substrate side is low and the N concentration on the surface side is high. A substrate with a conductive film is described.

Patent Document 2 describes a substrate with a conductive film used for manufacturing a reflective mask blank for EUV lithography, and the main material of the conductive film is a group consisting of Cr, Ti, Zr, Nb, Ni and V. Consisting of at least one selected, the conductive film contains B (boron) at an average concentration of 1 to 70 at%, and the conductive film has a low B average concentration on the substrate side and a high B average concentration on the surface side. As such, a substrate with a conductive film, which is an inclined composition film in which the concentration of B in the conductive film changes along the thickness direction of the conductive film, is described.

Patent Document 3 describes a method for correcting an error in a transfer mask for photolithography. Specifically, in Patent Document 3, the surface or the inside of the substrate is modified by locally irradiating the substrate of the transfer mask with a femtosecond laser pulse to correct the error of the transfer mask. It is stated that it should be done. Patent Document 3 exemplifies a sapphire laser (wavelength 800 nm), an Nd-YAG laser (532 nm), and the like as lasers that generate femtosecond laser pulses.

Patent Document 4 describes a substrate for a photolithography mask including a coating deposited on the back surface of the substrate. Patent Document 4 states that the coating comprises at least one first layer containing at least one metal and at least one second layer containing at least one metal nitride, and at least one first layer. The layer is described to include at least one conductive layer containing nickel (Ni), chromium (Cr), or titanium (Ti).

Japanese Patent No. 4978626 Japanese Patent No. 5082857 Japanese Patent No. 5883249 Japanese Patent No. 6107829

Patent Document 3 describes a method of correcting an error of a mask for photolithography by using a laser beam. When applying the technique described in Patent Document 3 to a reflective mask, it is conceivable to irradiate a laser beam from the second main surface (back surface) side of the substrate. However, since a back surface conductive film made of a material containing chromium (Cr) or the like (sometimes simply referred to as “conductive film”) is arranged on the second main surface of the substrate of the reflective mask, a laser beam can be applied. There is a problem that it is difficult to penetrate.

Further, in recent years, the required level of pattern position accuracy for a reflective mask has become particularly strict. One element for achieving high pattern position accuracy is to improve the flatness of the reflective mask blank, which is the original plate for producing the reflective mask. In order to improve the flatness of the reflective mask blank, it is necessary to improve the flatness of the mask blank substrate, but that alone is not sufficient. If the film stresses of the thin films formed on the main surface and the back surface of the mask blank substrate are not balanced, the substrate will be deformed and the flatness will be deteriorated.

When the flatness of the reflective mask blank deteriorates, when the transfer pattern of the reflective mask produced from the reflective mask blank is transferred onto the wafer, the image formation position of the pattern shifts from the wafer surface, resulting in poor pattern transfer accuracy. Deterioration occurs, the dimensions of the circuit pattern formed on the wafer deviate, and there arises a problem that a semiconductor device having the expected performance cannot be obtained. Further, if the flatness of the reflective mask blank deteriorates, when the transfer pattern of the reflective mask is transferred onto the wafer, the position where the pattern is formed deviates from the desired position, such as the switching speed of the transistor and the leakage current. There is also a problem that it is not possible to obtain a semiconductor device that can exhibit the characteristics of the above as expected. The amount of deviation of the pattern formation position from a desired position is called overlay accuracy (superimposition accuracy), but as the circuit size of the semiconductor device becomes smaller, smaller overlay accuracy is required.

Therefore, it is desired to increase the flatness of the reflective mask blank by balancing the film stresses on the back surface side and the front surface side. The back surface conductive film also needs to satisfy the required values of sheet resistance, surface roughness and mechanical strength.

Therefore, an object of the present invention is to provide a reflective mask having excellent flatness and capable of correcting the positional deviation of the reflective mask from the back surface side by a laser beam or the like. Further, the present invention includes a substrate with a conductive film, a substrate with a multilayer reflective film, and a substrate with a conductive film for producing a reflective mask having excellent flatness and capable of correcting the misalignment of the reflective mask from the back surface side by a laser beam or the like. The purpose is to obtain a reflective mask blank.

When a back surface conductive film having a predetermined composition made of a material containing titanium (Ti) and nitrogen (N) is used as the back surface conductive film, the inventors have high transmittance for a wavelength of 532 nm and low film stress. We found that there was, and came to the present invention.

In order to solve the above problems, the present invention has the following configurations.

(Structure 1)
The configuration 1 of the present invention is a substrate with a conductive film in which a conductive film is formed on one surface on the main surface of the substrate for mask blank used for lithography. The conductive film is made of a material containing titanium (Ti) and nitrogen (N). The material has a total content of titanium and nitrogen of 95 atomic% or more, and contains more titanium than titanium nitride having a stoichiometric composition.

The back surface conductive film arranged on the conductive film-attached substrate of the configuration 1 of the present invention can transmit a laser beam having a wavelength of 532 nm or the like. Further, the film stress of titanium nitride having a chemical quantitative composition is too large, and it is difficult to balance the film stress with the film stress on the surface side of the multilayer reflective film or the like. With a predetermined composition, the film stress can be made smaller than that of titanium nitride having a chemical quantitative composition, and can be balanced with the film stress on the surface side of a multilayer reflective film or the like, and the amount of deformation of the substrate can be reduced. can do. Therefore, according to the configuration 1 of the present invention, there is provided a substrate with a conductive film for manufacturing a reflective mask having excellent flatness and capable of correcting the positional deviation of the reflective mask from the back surface side by a laser beam or the like. can do.

(Structure 2)
In the configuration 2 of the present invention, the conductive film has the intensity value of the diffraction peak of TiN (200), the intensity value of the diffraction peak of TiN (200), and TiN (200) in the intensity of the diffraction peak by X-ray diffraction. 111) The substrate with a conductive film of the configuration 1 is characterized in that the ratio divided by the total value of the intensity values of the diffraction peaks is 0.4 or more.

In a material containing titanium and nitrogen, when the value of the intensity of the diffraction peak of TiN (200) is increased as compared with the value of the intensity of the diffraction peak of TiN (111), the film stress becomes smaller. According to the configuration 2 of the present invention, when the ratio of the intensity values of the diffraction peaks of TiN (200) is equal to or more than a predetermined ratio, the film stress of the conductive film is made smaller than that of titanium nitride having a stoichiometric composition. This makes it possible to reduce the amount of deformation of the substrate.

(Structure 3)
Configuration 3 of the present invention is a substrate with a conductive film according to configuration 1 or 2, wherein the film thickness of the conductive film is 10 nm or more and 30 nm or less.

According to the configuration 3 of the present invention, when the conductive film has a predetermined film thickness, a conductive film having more appropriate transmittance and conductivity can be obtained.

(Structure 4)
In the configuration 4 of the present invention, a high refractive index layer and a low refractive index layer are formed on the main surface of the substrate with a conductive film according to any one of configurations 1 to 3 on the side opposite to the side on which the conductive film is formed. It is a substrate with a multi-layered reflective film, characterized in that a multi-layered reflective film in which is alternately laminated is formed.

According to the configuration 4 of the present invention, EUV light having a predetermined wavelength can be reflected by a predetermined multilayer reflective film.

(Structure 5)
The configuration 5 of the present invention is a substrate with a multilayer reflective film of the configuration 4, wherein a protective film is formed on the multilayer reflective film.

According to the configuration 5 of the present invention, since the protective film is formed on the multilayer reflective film, it is applied to the surface of the multilayer reflective film when a reflective mask (EUV mask) is manufactured using the substrate with the multilayer reflective film. Since damage can be suppressed, the reflectance characteristic for EUV light becomes good.

(Structure 6)
The configuration 6 of the present invention is a reflective mask characterized in that an absorber film is formed on the multilayer reflective film of the substrate with the multilayer reflective film of the configuration 4 or on the protective film of the configuration 5. It is blank.

According to the configuration 6 of the present invention, since the absorber film of the reflective mask blank can absorb EUV light, the reflective mask (EUV) of the present invention is formed by patterning the absorber film of the reflective mask blank. Mask) can be manufactured.

(Structure 7)
A reflective mask according to the present invention is characterized in that the absorber film of the reflective mask blank of the present invention is patterned to have an absorber pattern on the multilayer reflective film or on the protective film. Is.

According to the configuration 7 of the present invention, it is possible to obtain a reflective mask having excellent flatness and capable of correcting the positional deviation of the reflective mask from the back surface side by a laser beam or the like.

(Structure 8)
The configuration 8 of the present invention comprises a step of forming a transfer pattern on a transfer target by performing a lithography process using an exposure apparatus using the reflective mask of the configuration 7 to manufacture a semiconductor device. The method.

According to the method for manufacturing a semiconductor device according to the configuration 8 of the present invention, a reflective mask having excellent flatness and capable of correcting the misalignment of the reflective mask from the back surface side by a laser beam or the like is manufactured for the semiconductor device. Can be used for Therefore, it is possible to manufacture a semiconductor device having a fine and highly accurate transfer pattern.

According to the present invention, it is possible to provide a reflective mask having excellent flatness and capable of correcting the positional deviation of the reflective mask from the back surface side by a laser beam or the like. Further, according to the present invention, a substrate with a conductive film and a multilayer reflective film for producing a reflective mask having excellent flatness and capable of correcting the positional deviation of the reflective mask from the back surface side by a laser beam or the like. A substrate and a reflective mask blank can be obtained.

It is sectional drawing which shows an example of the structure of the substrate with a conductive film of one Embodiment of this invention. It is sectional drawing which shows an example of the structure of the substrate with the multilayer reflective film of one Embodiment of this invention. It is sectional drawing which shows an example of the structure of the substrate with a multilayer reflective film (the substrate with a conductive film) of one embodiment of the present invention. It is sectional drawing which shows an example of the structure of the reflective mask blank of one Embodiment of this invention. It is sectional drawing which shows an example of the reflection type mask of one Embodiment of this invention. It is sectional drawing which shows another example of the structure of the reflective mask blank of one Embodiment of this invention. It is a process diagram which showed the process of manufacturing the reflective mask from the reflective mask blank by the sectional schematic diagram. It is a schematic diagram for demonstrating the measurement of a crack generation load.

Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. It should be noted that the following embodiments are embodiments for embodying the present invention, and do not limit the present invention to the scope thereof.

The present invention is a substrate with a conductive film in which a conductive film is formed on one surface on the main surface of the substrate for mask blank. Of the main surface of the mask blank substrate, the main surface on which the conductive film (also referred to as “back surface conductive film”) is formed is referred to as “back surface”. Further, in the present invention, a high refractive index layer and a low refractive index layer are alternately arranged on a main surface (sometimes referred to as a “front surface”) on which a conductive film is not formed on a substrate with a conductive film. It is a substrate with a multilayer reflective film on which a multilayer reflective film laminated on the surface is formed.

Further, the present invention is a reflective mask blank having a multilayer film for a mask blank including an absorber film on a multilayer reflective film of a substrate with a multilayer reflective film.

FIG. 1 is a schematic view showing an example of the conductive film-attached substrate 50 of the present invention. The conductive film-attached substrate 50 of the present invention has a structure in which the back surface conductive film 23 is formed on the back surface of the mask blank substrate 10. In the present specification, the conductive film-attached substrate 50 is one in which the back surface conductive film 23 is formed on at least the back surface of the mask blank substrate 10, and the multilayer reflective film 21 is formed on the other main surface. The substrate 50 with a conductive film also includes a substrate with a multilayer reflective film 20 and a substrate with an absorber film 24 formed therein (reflective mask blank 30). In the present specification, the back surface conductive film 23 may be simply referred to as a conductive film 23.

FIG. 2 shows an example of the substrate 20 with a multilayer reflective film. The multilayer reflective film 21 is formed on the main surface of the substrate 20 with the multilayer reflective film shown in FIG. FIG. 3 shows a substrate 20 with a multilayer reflective film having a back surface conductive film 23 formed on the back surface. The substrate 20 with a multilayer reflective film shown in FIG. 3 is a kind of the substrate 50 with a conductive film because the back surface conductive film 23 is included on the back surface thereof.

FIG. 6 is a schematic view showing an example of the reflective mask blank 30 of the present invention. The reflective mask blank 30 of the present invention has a mask blank multilayer film 26 on the main surface of the mask blank substrate 10. In the present specification, the mask blank multilayer film 26 includes the multilayer reflective film 21 and the absorber film 24 formed by being laminated on the main surface of the mask blank substrate 10 in the reflective mask blank 30. Multiple membranes. The mask blank multilayer film 26 further includes a protective film 22 formed between the multilayer reflective film 21 and the absorber film 24, and / or an etching mask film 25 formed on the surface of the absorber film 24 and the like. Can be done. In the case of the reflective mask blank 30 shown in FIG. 6, the mask blank multilayer film 26 on the main surface of the mask blank substrate 10 is a multilayer reflective film 21, a protective film 22, an absorber film 24, and an etching mask film. Has 25. When the reflective mask blank 30 having the etching mask film 25 is used, the etching mask film 25 may be peeled off after forming a transfer pattern on the absorber film 24 as described later. Further, in the reflective mask blank 30 that does not form the etching mask film 25, the absorber film 24 has a laminated structure of a plurality of layers, and the materials constituting the plurality of layers have different etching characteristics to provide an etching mask function. A reflective mask blank 30 having the absorber film 24 may be used. The reflective mask blank 30 of the present invention includes a back surface conductive film 23 on the back surface thereof. Therefore, the reflective mask blank 30 shown in FIG. 6 is a kind of the substrate 50 with a conductive film.

In the present specification, "having the multilayer reflective film 21 on the main surface of the mask blank substrate 10" means that the multilayer reflective film 21 is arranged in contact with the surface of the mask blank substrate 10. In addition to the case where the mask blank is used, it also includes a case where it means that another film is provided between the mask blank substrate 10 and the multilayer reflective film 21. The same applies to other membranes. For example, "having a film B on the film A" means that the film A and the film B are arranged so as to be in direct contact with each other, and another film is provided between the film A and the film B. Including the case of having. Further, in the present specification, for example, "the film A is arranged in contact with the surface of the film B" means that the film A and the film B are placed between the film A and the film B without interposing another film. It means that they are arranged so as to be in direct contact with each other.

FIG. 4 is a schematic view showing another example of the reflective mask blank 30 of the present invention. In the case of the reflective mask blank 30 of FIG. 4, the mask blank multilayer film 26 has the multilayer reflective film 21, the protective film 22, and the absorber film 24, but does not have the etching mask film 25. .. Further, the reflective mask blank 30 of FIG. 4 includes a back surface conductive film 23 on the back surface thereof. Therefore, the reflective mask blank 30 shown in FIG. 4 is a kind of the substrate 50 with a conductive film.

Next, the surface roughness (Rms), which is a parameter indicating the surface morphology of the surface of the mask blank substrate 10 and the surface of the film constituting the reflective mask blank 30 and the like, will be described.

Rms (Root means square), which is a typical index of surface roughness, is the root mean square roughness, which is the square root of the value obtained by averaging the squares of the deviations from the mean line to the measurement curve. Rms is expressed by the following equation (1).

式（１）において、ｌは基準長さであり、Ｚは平均線から測定曲線までの高さである。

In formula (1), l is the reference length and Z is the height from the average line to the measurement curve.

Rms has been conventionally used for controlling the surface roughness of the mask blank substrate 10, and the surface roughness can be grasped numerically.

Next, CTIR (Coordinate Total Indicator Reading) will be described as a parameter indicating the amount of deformation of the substrate due to the film stress of the film constituting the reflective mask blank 30 and the like. First, the main surface (back surface) of the mask blank substrate 10 before the conductive film 23 is formed is measured to obtain the surface shape of the substrate before the film formation of the conductive film 23. Next, the surface of the conductive film-attached substrate 50 on which the conductive film 23 is formed on the main surface (back surface) of the mask blank substrate 10 is measured to obtain the surface shape of the conductive film 23 after the film formation. CTIR calculates a difference shape between the surface shape of the substrate 10 and the surface shape of the conductive film 23, and is an absolute value of the difference between the highest value and the lowest value in this difference shape.

The surface shape can be performed using a surface shape analysis device (surface shape measurement device). As a method for measuring the surface shape, a known method can be used. Since the surface shape can be measured with high accuracy in a short time, it is preferable to use a method for measuring the surface shape using the interference fringes of the irradiated light. Such a device for measuring the surface shape irradiates the entire measurement area of the object to be measured with inspection light having a strong coherent tendency such as laser light, and has the light reflected by the surface and high flatness. An interference fringe image is generated with the light reflected by the reference surface, and the surface shape of the substrate is acquired by analyzing the interference fringe image. As such an apparatus (surface shape analysis apparatus), for example, UltraFLAT 200M (manufactured by Corning TOPEL) can be used.

The surface shape can be generally measured by the following method. First, measurement points are arranged in a grid shape on the surface of the measurement target, and height information of each measurement point (the reference plane at this time is, for example, a reference plane of the measurement device) is acquired by the surface shape measurement device. To do. Next, based on the height information of each measurement point, a plane approximated by the least squares method (least squares plane) is calculated, and this is used as a reference plane. Next, the height information of each of the above measurement points is converted into the height of each measurement point with reference to the reference plane (least squares plane), and the result is used as information on the surface shape at each measurement point. ..

The size of the measurement area of the surface shape can be appropriately selected depending on the size of the substrate, the size of the pattern when used as a reflective mask, the size of the electrostatic chuck, and the like. Here, the measurement region is 132 mm × 132 nm.

Next, the substrate with a conductive film 50, the substrate with a multilayer reflective film 20, the reflective mask blank 30, and the reflective mask 40 of the present invention will be described in more detail. First, the substrate 50 with a conductive film, the substrate 20 with a multilayer reflective film, the reflective mask blank 30, and the mask blank substrate 10 used for the reflective mask 40 (sometimes simply referred to as “subject 10”) of the present invention will be described. To do.

[Mask blank substrate 10]
As the substrate 10, a substrate 10 having a low coefficient of thermal expansion within the range of 0 ± 5 ppb / ° C. is preferably used in order to prevent distortion of the absorber pattern 24a due to heat during exposure with EUV light. As a material having a low coefficient of thermal expansion in this range, for example, SiO _2- TiO _2- based glass, multi-component glass ceramics, or the like can be used.

The first main surface on the side where the transfer pattern (absorbent pattern 24a described later) of the substrate 10 is formed is surface-processed so as to have high flatness from the viewpoint of obtaining at least pattern transfer accuracy and position accuracy. In the case of EUV exposure, the flatness is preferably 0.1 μm or less, more preferably 0.05 μm or less, still more preferably 0.05 μm or less in the region of 132 mm × 132 mm on the main surface on the side where the transfer pattern of the substrate 10 is formed. It is 0.03 μm or less. The second main surface opposite to the first main surface is a surface that is electrostatically chucked when set in the exposure apparatus. The flatness of the second main surface is preferably 0.1 μm or less, more preferably 0.05 μm or less, still more preferably 0.03 μm or less in a region of 132 mm × 132 mm. The flatness of the second main surface side of the reflective mask blank 30 is preferably 1 μm or less, more preferably 0.5 μm or less, still more preferably 0.3 μm or less in the region of 142 mm × 142 mm. Is.

Further, the high surface smoothness of the substrate 10 is also an extremely important item. The surface roughness of the first main surface on which the absorber pattern 24a for transfer is formed is preferably 0.1 nm or less in terms of root mean square roughness (RMS). The surface smoothness can be measured with an atomic force microscope.

Further, the substrate 10 preferably has high rigidity in order to prevent deformation of the film (multilayer reflective film 21 or the like) formed on the substrate 10 due to film stress. In particular, the substrate 10 preferably has a high Young's modulus of 65 GPa or more.

The substrate 20 with a multilayer reflective film of the present invention can have a base film in contact with the surface of the substrate 10. The base film is a thin film formed between the substrate 10 and the multilayer reflective film 21. By having the base film, it is possible to prevent charge-up during mask pattern defect inspection by an electron beam, reduce phase defects of the multilayer reflective film 21, and obtain high surface smoothness.

As the material of the base film, a material containing ruthenium or tantalum as a main component is preferably used. For example, Ru metal alone or Ta metal alone may be used, and Ru or Ta may be titanium (Ti), niobium (Nb), molybdenum (Mo), zirconium (Zr), yttrium (Y), boron (B), or lantern (La). ), Cobalt (Co), Renium (Re) and other metals may be contained in Ru alloys or Ta alloys. The film thickness of the base film can be in a range that does not adversely affect the predetermined light transmittance of the back surface conductive film 23. The film thickness of the base film can be, for example, in the range of 1 nm to 10 nm.

[Substrate 20 with multilayer reflective film]
Next, the substrate 20 with a multilayer reflective film that can be used for the substrate 50 with a conductive film and the reflective mask blank 30 of the present invention will be described below.

FIG. 2 is a schematic view showing an example of a substrate 20 with a multilayer reflective film that can be used for the back surface conductive film 23 and the reflective mask blank 30 of the present invention. Further, FIG. 3 shows a schematic view of another example of the substrate 20 with a multilayer reflective film of the present invention. As shown in FIG. 3, when the substrate 20 with a multilayer reflective film has a predetermined back surface conductive film 23, the substrate 20 with a multilayer reflective film is a kind of the back surface conductive film 23 of the present invention. In the present specification, the substrate 20 with a multilayer reflective film shown in both FIGS. 2 and 3 is referred to as the substrate 20 with a multilayer reflective film of the present embodiment.

<Multilayer reflective film 21>
The substrate 20 with a multilayer reflective film of the present embodiment is a multilayer reflective film 21 in which high refractive index layers and low refractive index layers are alternately laminated on a main surface opposite to the side on which the back surface conductive film 23 is formed. Is formed. The substrate 20 with a multilayer reflective film of the present embodiment can reflect EUV light having a predetermined wavelength by having a predetermined multilayer reflective film 21.

As shown in FIG. 2, in the present invention, the multilayer reflective film 21 can be formed before the back surface conductive film 23 is formed. Further, the back surface conductive film 23 may be formed as shown in FIG. 1, and then the multilayer reflective film 21 may be formed as shown in FIG.

The multilayer reflective film 21 imparts a function of reflecting EUV light in the reflective mask 40. The multilayer reflective film 21 has a configuration of a multilayer film in which each layer containing elements having different refractive indexes as main components is periodically laminated.

Generally, as the multilayer reflective film 21, a thin film (high refractive index layer) of a light element or a compound thereof which is a high refractive index material and a thin film (low refractive index layer) of a heavy element or a compound thereof which is a low refractive index material. A multilayer film in which and are alternately laminated for about 40 to 60 cycles is used. The multilayer film may be laminated for a plurality of cycles with the laminated structure of the high refractive index layer / low refractive index layer in which the high refractive index layer and the low refractive index layer are laminated in this order from the substrate 10 side as one cycle. A laminated structure of a low refractive index layer / a high refractive index layer in which a low refractive index layer and a high refractive index layer are laminated in this order may be laminated for a plurality of cycles. The outermost surface layer of the multilayer reflective film 21 (that is, the surface layer on the side opposite to the substrate 10 of the multilayer reflective film 21) is preferably a high refractive index layer. In the above-mentioned multilayer film, when a laminated structure (high refractive index layer / low refractive index layer) in which a high refractive index layer and a low refractive index layer are laminated in this order is laminated on the substrate 10 for a plurality of cycles, the uppermost layer is It becomes a low refractive index layer. Since the low refractive index layer on the outermost surface of the multilayer reflective film 21 is easily oxidized, the reflectance of the multilayer reflective film 21 is reduced. In order to avoid a decrease in the reflectance, it is preferable to further form a high refractive index layer on the uppermost low refractive index layer to form the multilayer reflective film 21. On the other hand, in the above-mentioned multilayer film, when a laminated structure (low refractive index layer / high refractive index layer) in which a low refractive index layer and a high refractive index layer are laminated in this order on the substrate 10 is set as one cycle, and a plurality of cycles are laminated. , The uppermost layer is a high refractive index layer. In this case, it is not necessary to further form the high refractive index layer.

In the present embodiment, a layer containing silicon (Si) is adopted as the high refractive index layer. As the material containing Si, a Si compound containing boron (B), carbon (C), nitrogen (N), and / or oxygen (O) can be used in addition to Si alone. By using a layer containing Si as a high refractive index layer, a reflective mask 40 for EUV lithography having excellent reflectance of EUV light can be obtained. Further, in the present embodiment, a glass substrate is preferably used as the substrate 10. Si is also excellent in adhesion to a glass substrate. Further, as the low refractive index layer, a simple substance of a metal selected from molybdenum (Mo), ruthenium (Ru), rhodium (Rh), and platinum (Pt), or an alloy thereof is used. For example, as the multilayer reflective film 21 for EUV light having a wavelength of 13 nm to 14 nm, a Mo / Si periodic laminated film in which Mo film and Si film are alternately laminated for about 40 to 60 cycles is preferably used. The high-refractive index layer, which is the uppermost layer of the multilayer reflective film 21, is formed of silicon (Si), and a silicon oxide containing silicon and oxygen is formed between the uppermost layer (Si) and the Ru-based protective film 22. Layers can be formed. By forming the silicon oxide layer, the cleaning resistance of the reflective mask 40 can be improved.

The reflectance of the above-mentioned multilayer reflective film 21 alone is usually 65% or more, and the upper limit is usually 73%. The thickness and period of each constituent layer of the multilayer reflective film 21 can be appropriately selected depending on the exposure wavelength, and can be selected so as to satisfy, for example, Bragg's reflection law. In the multilayer reflective film 21, a plurality of high refractive index layers and a plurality of low refractive index layers are present. The thicknesses of the plurality of high refractive index layers do not have to be the same, and the thicknesses of the plurality of low refractive index layers do not have to be the same. Further, the film thickness of the Si layer on the outermost surface of the multilayer reflective film 21 can be adjusted within a range that does not reduce the reflectance. The film thickness of Si (high refractive index layer) on the outermost surface can be 3 nm to 10 nm.

A method for forming the multilayer reflective film 21 is known. For example, it can be formed by forming each layer of the multilayer reflective film 21 by an ion beam sputtering method. In the case of the Mo / Si periodic multilayer film described above, for example, by the ion beam sputtering method, a Si film having a thickness of about 4 nm is first formed on the substrate 10 using a Si target, and then a thickness of 3 nm is formed using the Mo target. A degree of Mo film is formed. The Si film / Mo film is laminated for 40 to 60 cycles with one cycle as one cycle to form the multilayer reflective film 21 (the outermost layer is a Si layer). Further, when the multilayer reflective film 21 is formed, it is preferable to supply krypton (Kr) ion particles from an ion source and perform ion beam sputtering to form the multilayer reflective film 21.

<Protective film 22>
The substrate 20 with a multilayer reflective film of the present embodiment has a protective film 22 in which the mask blank multilayer film 26 is arranged in contact with the surface of the multilayer reflective film 21 opposite to the mask blank substrate 10. Further, it is preferable to include it.

The protective film 22 is formed on the multilayer reflective film 21 in order to protect the multilayer reflective film 21 from dry etching and cleaning in the manufacturing process of the reflective mask 40 described later. Further, when the black defect of the absorber pattern 24a is corrected by using the electron beam (EB), the multilayer reflective film 21 can be protected by the protective film 22. The protective film 22 can have a laminated structure of three or more layers. For example, the bottom layer and the top layer of the protective film 22 are made of the above-mentioned Ru-containing substance, and a metal other than Ru or an alloy of a metal other than Ru is interposed between the bottom layer and the top layer. It can be a structure. The material of the protective film 22 is composed of, for example, a material containing ruthenium as a main component. As a material containing ruthenium as a main component, Ru metal alone or Ru in titanium (Ti), niobium (Nb), molybdenum (Mo), zirconium (Zr), yttrium (Y), boron (B), lantern (La) ), Cobalt (Co), and / or Ruthenium containing metals such as ruthenium (Re) can be used. In addition, the material of these protective films 22 can further contain nitrogen. The protective film 22 is effective when the absorber film 24 is patterned by dry etching of a Cl-based gas.

When a Ru alloy is used as the material of the protective film 22, the Ru content ratio of the Ru alloy is 50 atomic% or more and less than 100 atomic%, preferably 80 atomic% or more and less than 100 atomic%, and more preferably 95 atomic% or more and less than 100 atomic%. Is. In particular, when the Ru content ratio of the Ru alloy is 95 atomic% or more and less than 100 atomic%, the reflectance of EUV light is increased while suppressing the diffusion of the element (silicon) constituting the multilayer reflective film 21 on the protective film 22. It can be secured sufficiently. Further, the protective film 22 can have a mask cleaning resistance, an etching stopper function when the absorber film 24 is etched, and a protective function for preventing the multilayer reflective film 21 from changing with time.

In the case of EUV lithography, since there are few substances that are transparent to the exposure light, EUV pellicle that prevents foreign matter from adhering to the mask pattern surface is not technically easy. For this reason, pellicle-less operation that does not use pellicle has become the mainstream. Further, in the case of EUV lithography, exposure contamination occurs such that a carbon film is deposited on the mask and an oxide film is grown due to EUV exposure. Therefore, when the EUV reflective mask 40 is used in the manufacture of a semiconductor device, it is necessary to frequently perform cleaning to remove foreign matter and contamination on the mask. For this reason, the EUV reflective mask 40 is required to have an order of magnitude more mask cleaning resistance than the transmissive mask for optical lithography. When the Ru-based protective film 22 containing Ti is used, cleaning resistance to cleaning liquids such as sulfuric acid, sulfuric acid hydrogen peroxide (SPM), ammonia, ammonia hydrogen peroxide (APM), OH radical cleaning water and ozone water having a concentration of 10 ppm or less is used. Can be especially high. Therefore, it is possible to satisfy the requirement of mask cleaning resistance for the EUV reflective mask 40.

The thickness of the protective film 22 is not particularly limited as long as it can function as the protective film 22. From the viewpoint of the reflectance of EUV light, the thickness of the protective film 22 is preferably 1.0 nm to 8.0 nm, more preferably 1.5 nm to 6.0 nm.

As a method for forming the protective film 22, the same method as a known film forming method can be adopted without particular limitation. Specific examples of the method for forming the protective film 22 include a sputtering method and an ion beam sputtering method.

[Substrate 50 with conductive film]
Next, the substrate 50 with a conductive film of the present invention will be described. In the substrate 20 with a multilayer reflective film shown in FIG. 2, a predetermined back surface conductive film 23 is formed on a surface of the substrate 10 opposite to the surface in contact with the multilayer reflective film 21, whereby the present invention as shown in FIG. 3 A substrate 50 with a conductive film can be obtained. The conductive film-attached substrate 50 of the present invention does not necessarily have to have the multilayer reflective film 21. As shown in FIG. 1, the substrate 50 with a conductive film of the present invention can also be obtained by forming a predetermined back surface conductive film 23 on one surface on the main surface of the mask blank substrate 10.

In the conductive film-attached substrate 50 of the present invention, the conductive film 23 (back surface conductive film 23) is formed on one surface (back surface) on the main surface of the mask blank substrate 10 used for lithography. The conductive film 23 is made of a material containing titanium (Ti) and nitrogen (N). The total content of titanium and nitrogen in the material containing titanium and nitrogen is 95 atomic% or more. Materials containing titanium and nitrogen contain more titanium than titanium nitride (chemical formula: TiN) having a stoichiometric composition.

The material containing titanium and nitrogen for forming the conductive film 23 preferably contains more titanium than titanium nitride having a stoichiometric composition. That is, the ratio of the atomic% of titanium and the atomic% of nitrogen (atomic% of nitrogen / atomic% of titanium) in the material of the conductive film 23 is less than 1, preferably 0.95 or less, and is 0. More preferably, it is 9.9 or less. Since the material of the conductive film 23 contains a relatively large amount of titanium, the electrical conductivity of the material of the conductive film 23 can be increased. Therefore, the sheet resistance of the conductive film 23 can be lowered.

The conductive film 23 made of a material containing titanium and nitrogen can be a uniform film having a uniform concentration of titanium and nitrogen, except for the surface layer which is affected by surface oxidation. Further, the composition gradient film may be formed so that the concentration of titanium and / or nitrogen in the conductive film 23 changes along the thickness direction of the conductive film 23. Further, the conductive film 23 can be a laminated film composed of a plurality of layers having a plurality of different compositions as long as the effects of the present invention are not impaired. For example, the conductive film 23 may include an upper layer film arranged on the outermost surface of the conductive film 23 and / or an intermediate film arranged between the upper layer film and the conductive film main body.

The material for forming the conductive film 23 can further contain a metal other than titanium as long as the effect of the present invention is not impaired. Examples of metals other than titanium include highly conductive metals such as Ag, Au, Cu, Al, Mg, W and Co. The material for forming the conductive film 23 preferably does not contain non-metals other than nitrogen (for example, oxygen and boron). In particular, when the material contains boron, both the transmittance and the conductivity decrease. Therefore, it is preferable that the material for forming the conductive film 23 does not contain boron.

_{The conductive film 23 of the substrate 50 with a conductive film of the present invention has a value I (200)} of the intensity of the diffraction peak of TiN (200) and the intensity of the diffraction peak of TiN (200) in the intensity of the diffraction peak by X-ray diffraction. values _{I (200),} and the ratio obtained by dividing the sum of the values of _I of the intensity of diffraction peak ₍₁₁₁₎ of TiN (111) _{(I r)} is preferably 0.4 or more, 0.5 The above is more preferable, and 0.7 or more is further preferable. Ratio _{(I r)} can be calculated by the following equation.
_{I r = I (200) /} [I (200) + I (111)]

In a material containing titanium and nitrogen, when the value of the intensity of the diffraction peak of TiN (200) is increased as compared with the value of the intensity of the diffraction peak of TiN (111), the film stress becomes smaller. When the ratio of the intensity values of the diffraction peaks of TiN (200) is equal to or more than a predetermined ratio, the film stress of the conductive film 23 can be made smaller than that of titanium nitride having a stoichiometric composition, and the amount of deformation of the substrate can be reduced. Can be made smaller. The method for measuring the intensity of the diffraction peak will be described later.

The film thickness of the conductive film 23 can be selected from an appropriate film thickness in relation to the transmittance and the electrical conductivity in light having a wavelength of 532 nm. For example, if the electrical conductivity of the material is high, the film thickness can be made thin and the transmittance can be increased. Generally, the film thickness of the conductive film 23 of the conductive film-attached substrate 50 of the present invention is preferably 10 nm or more and 30 nm or less. When the conductive film 23 has a predetermined film thickness, a conductive film 23 having more appropriate transmittance and conductivity can be obtained. When the film thickness of the conductive film 23 is 20 nm or less, the transmittance is 20% or more, which is preferable.

The transmittance of the conductive film 23 at a wavelength of 532 nm is 10% or more, preferably 20% or more, and more preferably 25% or more. The transmittance at a wavelength of 632 nm is preferably 25% or more. The back surface of the conductive substrate 50 The reflective mask can be corrected from the back surface side by a laser beam or the like because the transmittance of light of a predetermined wavelength of the conductive film 23 is within a predetermined range. 40 can be obtained.

The sheet resistance of the conductive film 23 is preferably 150 Ω / □ (Ω / square) or less. When the sheet resistance is in a predetermined range, the electrical characteristics required for the conductive film 23 for an electrostatic chuck can be satisfied. The sheet resistance of the conductive film 23 can be controlled by adjusting the composition and film thickness of the conductive film 23.

The surface roughness of the conductive film 23 is preferably 0.6 nm or less, and the root mean square roughness (Rms) obtained by measuring a region of 10 μm × 10 μm with an atomic force microscope is preferably 0.3 nm or less. More preferred. Since the surface of the conductive film 23 has a predetermined root mean square roughness (Rms), it is possible to prevent the generation of particles due to rubbing between the electrostatic chuck and the conductive film 23.

The surface shape of the conductive film 23 is convex, and the amount of deformation (CTIR) of the substrate due to film stress in the region of 132 mm × 132 mm is preferably in the range of 350 nm ± 150 nm.

The mechanical strength of the conductive film 23 can be evaluated by measuring the crack generation load of the conductive film-attached substrate 50. The mechanical strength needs to be 300 mN or more in terms of the crack generation load. When the crack generation load is within a predetermined range, it can be said that the back surface conductive film 23 has the mechanical strength required as the conductive film 23 for the electrostatic chuck. The method of measuring the crack generation load will be described later.

A method for forming the back surface conductive film 23 is known. The back surface conductive film 23 can be formed by, for example, a magnetron sputtering method or an ion beam sputtering method. When forming a TiN film by sputtering using a Ti target, as a gas for sputtering is introduced Ar gas and N ₂ gas. A TiN film having a low nitriding degree can be obtained by adjusting the flow rate ratio of Ar gas and N _{2 gas, gas pressure, electric power, etc. at the time of film formation.} Further, by forming the conductive film 23 at a low voltage, it is possible to increase the adhesive force with the substrate and increase the crack generation load.

Specifically, the method of forming the back surface conductive film 23 is as follows: the substrate 10 is rotated on a horizontal plane with the surface to be formed of the substrate 10 for forming the back surface conductive film 23 facing upward, and the central axis of the substrate 10 is formed. The back surface conductive film is formed by inclining the sputtering target at a predetermined angle with respect to the surface to be filmed at a position deviated from a straight line passing through the center of the sputtering target and parallel to the central axis of the substrate 10. It is preferable to form a film of 23. The back surface conductive film 23 can be formed by arranging the sputtering target and the substrate 10 in such an arrangement and sputtering the opposing sputtering targets. The predetermined angle is preferably an angle at which the inclination angle of the sputtering target is 5 degrees or more and 30 degrees or less. The gas pressure during the sputtering film formation is preferably 0.03 Pa or more and 0.1 Pa or less. By forming the back surface conductive film 23 by such a method, it is possible to obtain the back surface conductive film 23 having a film stress smaller than that of titanium nitride having a stoichiometric composition.

The reflective mask 40 can be manufactured by using the conductive film-attached substrate 50 of the present invention. The conductive film 23 of the substrate 50 with a conductive film of the present invention can transmit a laser beam or the like having a wavelength of 532 nm. Further, since the back surface conductive film 23 arranged on the substrate 50 with a conductive film of the present invention is a conductive film 23 having a predetermined composition, the film stress is smaller than that of titanium nitride having a chemical quantitative composition, and a multilayer is formed. The stress on the surface side of the reflective film or the like can be easily balanced, and the amount of deformation of the substrate can be reduced. Therefore, according to the present invention, it is possible to obtain a substrate 50 with a conductive film for manufacturing a reflective mask 40 having excellent flatness and capable of correcting the positional deviation of the reflective mask from the back surface side by a laser beam or the like. Can be done. Further, the back surface conductive film of the substrate 50 with a conductive film of the present invention can satisfy other required values such as sheet resistance, surface roughness and mechanical strength.

[Reflective mask blank 30]
Next, the reflective mask blank 30 of the present invention will be described. FIG. 4 is a schematic view showing an example of the reflective mask blank 30 of the present invention. The reflective mask blank 30 of the present invention has a structure in which the absorber film 24 is formed on the multilayer reflective film 21 or the protective film 22 of the substrate 20 with the multilayer reflective film described above. The reflective mask blank 30 may further have an etching mask film 25 and / or a resist film 32 on the absorber film 24 (see FIG. 7A).

<Absorbent membrane 24>
The reflective mask blank 30 has an absorber film 24 on the above-mentioned substrate 20 with a multilayer reflective film. That is, the absorber film 24 is formed on the multilayer reflective film 21 (when the protective film 22 is formed, on the protective film 22). The basic function of the absorber membrane 24 is to absorb EUV light. The absorber film 24 may be an absorber film 24 for the purpose of absorbing EUV light, or may be an absorber film 24 having a phase shift function in consideration of the phase difference of EUV light. The absorber film 24 having a phase shift function absorbs EUV light and reflects a part of the EUV light to shift the phase. That is, in the reflective mask 40 in which the absorber film 24 having a phase shift function is patterned, the portion where the absorber film 24 is formed absorbs EUV light and dims, and the pattern transfer is not adversely affected. Reflects some light. Further, in the region (field portion) where the absorber film 24 is not formed, EUV light is reflected from the multilayer reflection film 21 via the protective film 22. Therefore, a desired phase difference is obtained between the reflected light from the absorber film 24 having the phase shift function and the reflected light from the field portion. The absorber film 24 having a phase shift function is formed so that the phase difference between the reflected light from the absorber film 24 and the reflected light from the multilayer reflective film 21 is 170 degrees to 190 degrees. The image contrast of the projected optical image is improved by the light having the inverted phase difference in the vicinity of 180 degrees interfering with each other at the pattern edge portion. As the image contrast is improved, the resolution is increased, and various exposure-related margins such as exposure amount margin and focal margin can be increased.

The absorber membrane 24 may be a single-layer membrane or a multilayer membrane composed of a plurality of membranes (for example, a lower-layer absorber membrane and an upper-layer absorber membrane). In the case of a single-layer film, the number of steps during mask blank manufacturing can be reduced and the production efficiency is improved. In the case of a multilayer film, its optical constant and film thickness can be appropriately set so that the upper layer absorber film becomes an antireflection film at the time of mask pattern defect inspection using light. This improves the inspection sensitivity at the time of mask pattern defect inspection using light. Further, when a membrane to which oxygen (O), nitrogen (N) or the like for improving oxidation resistance is added to the upper absorber membrane is used, the stability over time is improved. In this way, by making the absorber film 24 a multilayer film, it is possible to add various functions. When the absorber film 24 is an absorber film 24 having a phase shift function, the range of adjustment on the optical surface can be increased by forming a multilayer film, so that a desired reflectance can be easily obtained. Become.

As long as the material of the absorber film 24 has a function of absorbing EUV light and can be processed by etching or the like (preferably, it can be etched by dry etching of chlorine (Cl) or fluorine (F) -based gas). There is no particular limitation. As a substance having such a function, tantalum (Ta) alone or a material containing Ta can be preferably used.

Examples of the material containing Ta include a material containing Ta and B, a material containing Ta and N, a material containing Ta and B and at least one of O and N, a material containing Ta and Si, and a material containing Ta and Si. Examples include a material containing Ta and N, a material containing Ta and Ge, a material containing Ta, Ge and N, a material containing Ta and Pd, a material containing Ta and Ru, and a material containing Ta and Ti.

The absorber membrane 24 is, for example, a simple substance of Ni, a material containing Ni, a simple substance of Cr, a material containing Cr, a simple substance of Ru, a material containing Ru, a simple substance of Pd, a material containing Pd, a simple substance of Mo, and a material containing Mo. It can be formed of a material containing at least one selected from the group consisting of.

In order to properly absorb EUV light, the thickness of the absorber film 24 is preferably 30 nm to 100 nm.

The absorber membrane 24 can be formed by a known method, for example, a magnetron sputtering method, an ion beam sputtering method, or the like.

<Etching mask film 25>
An etching mask film 25 may be formed on the absorber film 24. As the material of the etching mask film 25, a material having a high etching selectivity of the absorber film 24 with respect to the etching mask film 25 is used. Here, the "etching selection ratio of B to A" refers to the ratio of the etching rate between A, which is a layer (mask layer) that is not desired to be etched, and B, which is a layer that is desired to be etched. Specifically, it is specified by the formula "etching selectivity of B with respect to A = etching rate of B / etching rate of A". Further, "high selection ratio" means that the value of the selection ratio defined above is large with respect to the comparison target. The etching selectivity of the absorber film 24 with respect to the etching mask film 25 is preferably 1.5 or more, and more preferably 3 or more.

Examples of the material having a high etching selectivity of the absorber film 24 with respect to the etching mask film 25 include a material of chromium and a chromium compound. Therefore, when the absorber film 24 is etched with a fluorine-based gas, a material of chromium or a chromium compound can be used. Examples of the chromium compound include a material containing Cr and at least one element selected from N, O, C and H. Further, when the absorber film 24 is etched with a chlorine-based gas that does not substantially contain oxygen, a material of silicon or a silicon compound can be used. Examples of the silicon compound include a material containing Si and at least one element selected from N, O, C and H, metallic silicon containing a metal in silicon and the silicon compound (metal silicide), and metallic silicon compound (metal silicide). Materials such as compound) can be mentioned. Examples of the metal silicon compound include a material containing a metal, Si, and at least one element selected from N, O, C, and H.

The film thickness of the etching mask film 25 is preferably 3 nm or more from the viewpoint of obtaining a function as an etching mask that accurately forms a transfer pattern on the absorber film 24. Further, the film thickness of the etching mask film 25 is preferably 15 nm or less from the viewpoint of reducing the film thickness of the resist film 32.

[Reflective mask 40]
Next, the reflective mask 40 according to the embodiment of the present invention will be described below. FIG. 5 is a schematic view showing the reflective mask 40 of the present embodiment.

The reflective mask 40 of the present invention has a structure in which the absorbent film 24 in the reflective mask blank 30 is patterned to form an absorbent pattern 24a on the multilayer reflective film 21 or on the protective film 22. .. When the reflective mask 40 of the present embodiment is exposed with exposure light such as EUV light, the exposure light is absorbed at a portion of the reflective mask 40 where the absorber film 24 is present, and the other absorber film 24 is removed. Since the exposed light is reflected by the exposed protective film 22 and the multilayer reflective film 21, it can be used as a reflective mask 40 for lithography.

According to the reflective mask 40 of the present invention, by having the absorber pattern 24a on the multilayer reflective film 21 (or on the protective film 22), a predetermined pattern can be transferred to the transferee using EUV light. it can.

Since the reflective mask 40 of the present invention has a transmittance of a predetermined wavelength or more of a predetermined value or more, the reflective mask of the present invention is used by a laser beam or the like by the method described in Patent Document 3 (Patent No. 583249). The misalignment of 40 can be corrected. Therefore, it can be said that the reflective mask 40 of the present invention can have a highly accurate transfer pattern.

[Manufacturing method of semiconductor devices]
A circuit pattern based on the absorber pattern 24a of the reflective mask 40 is formed on the resist film 32 formed on the transferred object such as a semiconductor substrate by the reflective mask 40 described above and the lithography process using an exposure apparatus. By transferring the transfer pattern and undergoing various other steps, it is possible to manufacture a semiconductor device in which various transfer patterns and the like are formed on a transfer object such as a semiconductor substrate.

That is, the present invention is a method for manufacturing a semiconductor device, which comprises a step of performing a lithography process using an exposure apparatus using the above-mentioned reflective mask 40 to form a transfer pattern on a transfer target.

According to the method for manufacturing a semiconductor device of the present invention, the displacement of the reflective mask can be corrected from the back surface side by a laser beam or the like by the method described in Patent Document 3 (Japanese Patent No. 583249). 40 can be used for the manufacture of semiconductor devices. Therefore, when the reflective mask 40 of the present invention is used for manufacturing a semiconductor device, it can be said that a semiconductor device having a fine and highly accurate transfer pattern can be manufactured.

Hereinafter, examples will be described with reference to the drawings.

(Example 1)
First, the conductive film-attached substrate 50 of Example 1 will be described.

The substrate 10 for manufacturing the conductive film-attached substrate 50 of Example 1 was prepared as follows. _{That is, a SiO 2-} TiO ₂ glass substrate, which is a 6025 size (about 152 mm × 152 mm × 6.35 mm) low thermal expansion glass substrate in which both the first main surface and the second main surface are polished, is prepared and the substrate is prepared. It was set to 10. Polishing was performed by a rough polishing process, a precision polishing process, a local processing process, and a touch polishing process so that the main surface was flat and smooth.

A back surface conductive film 23 made of a TiN film was formed on the second main surface (back surface) of the SiO _2- TiO _{2 system glass substrate 10 of Example 1 by a magnetron sputtering (reactive sputtering) method under the following conditions.}
Target: Ti target Film formation gas: _{Mixed gas atmosphere of Ar and N 2} (flow rate ratio, Ar: N ₂ = 2: 3).
Film formation gas pressure: 0.043 Pa
Power during film formation: 1500W
Film thickness: 16 nm

The composition (atomic%) of the conductive film 23 of Example 1 is Ti: N = 54: 46, and contains more titanium than titanium nitride having a stoichiometric composition. The N / Ti ratio obtained by dividing the nitrogen content by the titanium content was 0.85.

Table 1 shows the film thickness (nm) of Example 1 obtained as described above, the relative intensity of the TiN (200) peak, the sheet resistance (Ω / □), and the light transmittance (%) at a wavelength of 532 nm. It shows the mechanical strength (crack generation load, unit mN), surface roughness (Rms, unit: nm), and the amount of deformation of the substrate due to film stress (CTIR, nm). By measuring CTIR, it was confirmed that all the samples had a convex shape (the shape in which the conductive film 23 was outside the arc with respect to the substrate).

And "TiN (200) relative intensity of the peaks _{(I r)",} in the intensity of the diffraction peak by X-ray diffraction, the TiN (200) a value _{I (200)} of the intensity of the diffraction peaks of the diffraction of TiN (200) the intensity of the peak value _{I (200),} and a TiN rate divided by the sum of the values of _I of the intensity of diffraction peak ₍₁₁₁₎ of (111) _{(I r).
I r = I (200) /} [I (200) + I (111)]

The intensities of the diffraction peaks of TiN (200) and TiN (111) were measured as follows. That is, using an X-ray diffractometer SmartLab (manufactured by Rigaku Co., Ltd.), the sample is irradiated with characteristic X-rays of CuKα generated by a voltage of 45 kV and a current of 200 mA, and the intensity and diffraction angle (2θ) of the diffracted X-rays are measured. A diffracted peak of diffracted X-rays corresponding to a predetermined crystal plane was obtained. The intensity of the diffraction peak was determined by measuring the area of a predetermined peak. At that time, processing such as subtracting a predetermined background was performed using the software attached to the measuring device.

In order to evaluate the mechanical strength, the crack generation load of the conductive film-attached substrate 50 of Example 1 was measured. FIG. 8 shows a schematic diagram for explaining the measurement of the crack generation load. The crack generation load can be measured as follows. That is, the substrate 50 with a conductive film is placed on the stage 104 of the crack generation load measuring device 100. Next, the indenter 102 is arranged so as to come into contact with the conductive film 23 of the conductive film-attached substrate 50. The indenter 102 has a structure capable of pressing the tip of the indenter 102 against the conductive film 23 by applying a predetermined load. The tip of the indenter 102 has a shape having a predetermined radius of curvature. Next, the stage 104 is moved at a predetermined speed while increasing the load applied to the indenter 102 at a predetermined speed. The load of the indenter 102 when a crack was generated in the conductive film 23 of the conductive film-attached substrate 50 was defined as the crack generation load.

The measurement conditions for the crack generation load are as follows.
Initial load: 20mN
Final load: 1000mN
Indenter 102 load increasing speed: 400 mN / min Stage 104 moving speed: 1 mm / min Indenter 102 type: Rockwell
Curvature radius of the tip of the indenter 102: 20 μm

As described above, the substrate 50 with a conductive film of Example 1 was manufactured and evaluated.

(Comparative Example 1)
The substrate 50 with a conductive film of Comparative Example 1 was produced in the same manner as in Example 1 except that the film film of the conductive film 23 was formed under the following conditions.

A back surface conductive film 23 made of a TiN film was formed on the second main surface (back surface) of the substrate 10 of Comparative Example 1 in the same manner as in Example 1 under the following conditions by a magnetron sputtering (reactive sputtering) method. Among the film forming conditions of Comparative Example 1, the conditions different from those of Example 1 are the film forming gas and the film forming gas pressure.
Target: Ti target Film formation gas: _{Mixed gas atmosphere of Ar and N 2} (flow rate ratio, Ar: N ₂ = 3: 2).
Film formation gas pressure: 0.084 Pa
Power during film formation: 400W
Film thickness: 16 nm

The composition (atomic%) of the conductive film 23 of Comparative Example 1 was Ti: N = 50: 50, and it was titanium nitride having a stoichiometric composition.

Similar to Example 1, the relative intensity of the TiN (200) peak of Comparative Example 1, the sheet resistance (Ω / □), the light transmission rate (%) at a wavelength of 532 nm, the mechanical intensity (crack generation load, unit mN), The surface roughness (Rms, unit: nm) and the amount of deformation of the substrate due to film stress (CTIR, nm) were measured. Table 1 shows the measurement results. By measuring CTIR, it was confirmed that all the samples had a convex shape (the shape in which the conductive film 23 was outside the arc with respect to the substrate).

(Comparison of the conductive film-attached substrate 50 of Example 1 and Comparative Example 1)
As shown in Table 1, the sheet resistance of the conductive film 23 of the conductive film-attached substrate 50 of Example 1 and Comparative Example 1 is 150 Ω / □ or less, which is a value that is satisfactory as the back surface conductive film 23 of the reflective mask 40. It was. Similarly, the transmittance of light having a wavelength of 532 nm in Example 1 and Comparative Example 1 is 25% or more, the mechanical strength (crack generation load) is 300 mN or more, and the surface roughness (Rms) is 0.60 nm or less. Met. Therefore, the conductive substrate 50 of Example 1 and Comparative Example 1 has satisfactory values for the back surface conductive film 23 of the reflective mask 40 in terms of light transmittance, mechanical strength and surface roughness (Rms) at a wavelength of 532 nm. was. However, the CTIR of the conductive film 23 of Comparative Example 1 was 532 nm, which exceeded 500 nm, which is an acceptable upper limit as the back surface conductive film 23 for obtaining the reflective mask 40 having excellent flatness. On the other hand, the CTIR of the conductive film 23 of Example 1 was 359 nm, which was a satisfactory value as the back surface conductive film 23 of the reflective mask 40. From the above, it is clear from the present invention that the substrate 40 with a conductive film for producing a reflective mask having excellent flatness and capable of correcting the misalignment of the reflective mask with a laser beam or the like can be obtained. It became.

Next, the substrate 20 with a multilayer reflective film, the reflective mask blank 30, and the reflective mask 40 of Example 1 and Comparative Example 1 will be described.

On the main surface (first main surface) of the substrate 10 on the side opposite to the side on which the back surface conductive film 23 of the conductive film-attached substrate 50 manufactured as described above is formed, the multilayer reflective film 21 and the protective film 22 The substrate 20 with a multilayer reflective film was manufactured by forming the above. The reflective mask blank 30 was manufactured by forming the absorber film 24 on the protective film 22 of the substrate 20 with the multilayer reflective film. Specifically, the substrate 20 with a multilayer reflective film and the reflective mask blank 30 were manufactured as follows.

The multilayer reflective film 21 was formed on the main surface (first main surface) of the substrate 10 on the side opposite to the side on which the back surface conductive film 23 was formed. The multilayer reflective film 21 formed on the substrate 10 is a periodic multilayer reflective film 21 composed of Mo and Si in order to obtain a multilayer reflective film 21 suitable for EUV light having a wavelength of 13.5 nm. The multilayer reflective film 21 was formed by alternately laminating Mo layers and Si layers on a substrate 10 by an ion beam sputtering method in an Ar gas atmosphere using a Mo target and a Si target. First, a Si film was formed with a thickness of 4.2 nm, and then a Mo film was formed with a thickness of 2.8 nm. This was set as one cycle, and 40 cycles were laminated in the same manner, and finally a Si film was formed with a thickness of 4.0 nm to form a multilayer reflective film 21. Here, 40 cycles are used, but the cycle is not limited to this, and 60 cycles may be used, for example. When 60 cycles are used, the number of steps is larger than that of 40 cycles, but the reflectance to EUV light can be increased.

Subsequently, in an Ar gas atmosphere, a protective film 22 made of a Ru film was formed with a thickness of 2.5 nm by an ion beam sputtering method using a Ru target.

As described above, the substrate 20 with the multilayer reflective film of Example 1 and Comparative Example 1 was manufactured.

Next, the absorber film 24 was formed on the protective film 22 of the substrate 20 with the multilayer reflective film by the DC magnetron sputtering method. The absorber film 24 was a laminated film absorber film 24 composed of two layers, a TaBN film which is an absorption layer and a TaBO film which is a low reflection layer. A TaBN film was formed as an absorption layer on the surface of the protective film 22 of the substrate 20 with the multilayer reflective film described above by the DC magnetron sputtering method. In this TaBN film, a substrate 20 with a multilayer reflective film is opposed to a TaB mixed sintering target (Ta: B = 80: 20, atomic ratio), and reactive sputtering is performed in a mixed gas atmosphere of _{Ar gas and N 2 gas.} It was. Next, a TaBO film (low reflection layer) containing Ta, B and O was further formed on the TaBN film by the DC magnetron sputtering method. Similar to the TaBN film, this TaBO film reacts in a mixed gas atmosphere of _{Ar and O 2} with the substrate 20 with a multilayer reflective film facing the TaB mixed sintering target (Ta: B = 80: 20, atomic ratio). Sexual sputtering was performed.

The composition of the TaBN film was Ta: B: N = 74.7: 12.1: 13.2, and the film thickness was 56 nm. The composition of the TaBO film was Ta: B: O = 40.7: 6.3: 53.0, and the film thickness was 14 nm.

As described above, the reflective mask blanks 30 of Example 1 and Comparative Example 1 were manufactured.

Next, the reflective mask 40 was manufactured using the reflective mask blank 30 described above. FIG. 7 is a schematic cross-sectional view of a main part showing a process of manufacturing the reflective mask 40 from the reflective mask blank 30.

A reflective mask blank 30 formed by forming a resist film 32 with a thickness of 150 nm on the absorber film 24 of the reflective mask blank 30 of Example 1 and Comparative Example 1 described above (FIG. 7A). ). A desired pattern was drawn (exposed) on the resist film 32, further developed and rinsed to form a predetermined resist pattern 32a (FIG. 7 (b)). Next, the absorber film 24 was dry-etched using the resist pattern 32a as a mask to form the absorber pattern 24a (FIG. 7 (c)). When the absorber film 24 is a TaBN film, it can be dry-etched with a mixed gas of _{Cl 2 and He.} Also, if the absorber film 24 is a laminated film composed of two layers of TaBN film and TaBO film, a mixed gas of chlorine (Cl ₂₎ and oxygen _{(O 2)} (chlorine (Cl ₂₎ and oxygen _{(O 2} ) Can be dry-etched according to the mixing ratio (flow ratio) of 8: 2).

Then, the resist pattern 32a was removed by ashing or a resist stripping solution. Finally, wet cleaning with pure water (DIW) was performed to manufacture a reflective mask 40 (FIG. 7 (d)). If necessary, a mask defect inspection can be performed after wet cleaning, and the mask defect can be corrected as appropriate.

As described in the evaluation of the conductive substrate 50 of Example 1 and Comparative Example 1 described above, the conductive film 23 of the embodiment of the present invention has a light transmittance of 10% or more at a wavelength of 532 nm, and thus Patent Document 3 As described in (Patent No. 583249), the misalignment of the reflective mask 40 can be corrected by a laser beam or the like. Therefore, when the reflective mask 40 of the present invention is used for manufacturing a semiconductor device, it can be said that a semiconductor device having a fine and highly accurate transfer pattern can be manufactured.

As described in the evaluation of the conductive substrate 50 of Example 1 and Comparative Example 1 described above, the conductive substrate 50 having the conductive film 23 of Example 1 of the present invention has a amount of deformation of the substrate due to film stress. It is small and has excellent flatness. Therefore, the reflective mask 40 having the conductive film 23 of the present invention is also excellent in flatness. Further, since the reflective mask 40 having excellent flatness and capable of correcting the misalignment of the reflective mask from the back surface side by a laser beam or the like can be used for manufacturing a semiconductor device, it is fine and high. A semiconductor device having an accurate transfer pattern can be manufactured.

The reflective mask 40 produced in Example 1 was set in an EUV exposure apparatus, and EUV exposure was performed on a wafer on which a film to be processed and a resist film 32 were formed on a semiconductor substrate. Then, by developing the exposed resist film 32, a resist pattern 32a was formed on the semiconductor substrate on which the film to be processed was formed.

The resist pattern 32a is transferred to a film to be processed by etching, and a semiconductor device having desired characteristics is manufactured by undergoing various steps such as forming an insulating film, a conductive film, introducing a dopant, and annealing. Was made.

10 Mask blank substrate 20 Substrate with multi-layer reflective film 21 Multi-layer reflective film 22 Protective film 23 Conductive film (back surface conductive film)
24 Absorber film 24a Absorber pattern 25 Etching mask film 26 Multilayer film for mask blank 30 Reflective mask blank 32 Resist film 32a Resist pattern 40 Reflective mask 50 Conductive substrate 100 Crack generation load measuring device 102 Indenter 104 Stage

Claims (7)

A conductive film-attached substrate in which a conductive film is formed on one surface on the main surface of a mask blank substrate used for lithography.
The conductive film is made of a material containing titanium (Ti) and nitrogen (N), and the total content of titanium and nitrogen is 95 atomic% or more, and the material contains titanium rather than titanium nitride having a stoichiometric composition. many see including,
The conductive film has the intensity of the diffraction peak of TiN (200), the intensity of the diffraction peak of TiN (200), and the intensity of the diffraction peak of TiN (111) in the intensity of the diffraction peak by X-ray diffraction. A substrate with a conductive film , wherein the ratio divided by the total value of is 0.4 or more. The substrate with a conductive film according to claim 1, wherein the film thickness of the conductive film is 10 nm or more and 30 nm or less. Multilayer reflection in which high refractive index layers and low refractive index layers are alternately laminated on a main surface of the substrate with a conductive film according to claim 1 or 2 on the side opposite to the side on which the conductive film is formed. A substrate with a multilayer reflective film, characterized in that a film is formed. The substrate with a multilayer reflective film according to claim 3 , wherein a protective film is formed on the multilayer reflective film. A reflective mask blank characterized in that an absorber film is formed on the multilayer reflective film of the substrate with the multilayer reflective film according to claim 3 or on the protective film according to claim 4. .. A reflective mask according to claim 5 , wherein the absorber film of the reflective mask blank is patterned to have an absorber pattern on the multilayer reflective film or a protective film. A method for manufacturing a semiconductor device, which comprises a step of performing a lithography process using an exposure apparatus using the reflective mask according to claim 6 to form a transfer pattern on a transfer target.

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