JP6039207B2 - Method for manufacturing substrate with multilayer reflective film for EUV lithography, method for manufacturing reflective mask blank for EUV lithography, method for manufacturing reflective mask for EUV lithography, and method for manufacturing semiconductor device - Google Patents

Description

  The present invention relates to a substrate with a multilayer reflective film for EUV lithography and a method for manufacturing a reflective mask blank for EUV lithography used for manufacturing semiconductor devices. The present invention also relates to a reflective mask for EUV lithography and a method for manufacturing a semiconductor device using the same.

  In recent years, in the semiconductor industry, with the miniaturization of semiconductor devices, EUV lithography which is an exposure technique using extreme ultraviolet (Extreme Ultra Violet: 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. As a mask used in this EUV lithography, for example, a reflective mask for exposure described in Patent Document 1 has been proposed.

  The reflective mask described in Patent Document 1 is such that a multilayer reflective film that reflects exposure light is formed on a substrate, and an absorber film that absorbs exposure light is formed in a pattern on the multilayer reflective film. . Light incident on the reflective mask mounted on the exposure machine (pattern transfer device) is absorbed in a part where the absorber film is present, and light reflected by the multilayer reflective film is transmitted through the reflective optical system in a part where the absorber film is not present. Transferred onto a semiconductor substrate.

  In EUV lithography, an electrostatic chuck is used as one of support means for the reflective mask. In order to promote electrostatic chucking of the reflective mask, it has been proposed to form a conductive film on the surface of the substrate opposite to the multilayer reflective film. For example, Patent Document 2 discloses a substrate with a conductive film used for manufacturing a reflective mask blank for EUV lithography, wherein the conductive film contains chromium (Cr) and nitrogen (N). The average concentration of N is 0.1 at% or more and less than 40 at%, the crystalline state of at least the surface of the conductive film is amorphous, the sheet resistance value of the conductive film is 27 Ω / □ or less, and the surface of the conductive film A substrate with a conductive film is described which has a roughness (rms) of 0.5 nm or less.

On the other hand, Patent Documents 3 and 4 describe silica glass containing TiO ₂ used as an optical member for EUV lithography. Patent Document 3 discloses a TiO ₂ -containing silica glass having a TiO ₂ concentration of 3 to 12% by mass and a hydrogen molecule content of less than 5 × 10 ¹⁷ molecules / cm ³ . In Patent Document 4, the fictive temperature is 1100 ° C. or lower, the hydrogen molecule concentration is 5 × 10 ¹⁷ molecules / cm ³ or higher, and the temperature at which the linear thermal expansion coefficient is 0 ppb / ° C. is 4 to 40 ° C. TiO ₂ -containing silica glass is disclosed.

  Patent Document 5 discloses a light heating device that heats a workpiece by irradiating the workpiece with light emitted from a plurality of incandescent lamps.

Japanese Patent Publication No. 7-27198 International Publication No. 2008/72706 Pamphlet Japanese Patent No. 4487783 International Publication No. 2009/145288 Pamphlet JP 2001-210604 A

The required level of defect quality for reflective mask blanks and reflective masks is becoming stricter year by year. When manufacturing a reflective mask blank or a semiconductor device using a reflective mask, the reflective mask blank and the reflective mask are repeatedly attached to and detached from the electrostatic chuck. At this time, rubbing occurs between the reflective mask blank or the conductive film of the reflective mask and the electrostatic chuck. For this reason, after removing the reflective mask blank or reflective mask from the electrostatic chuck, the surface of the conductive film is usually cleaned with a chemical solution using acid or alkali. Patent Document 2 proposes to use a material containing chromium (Cr) and nitrogen (N), whose surface hardness is relatively high, for the conductive film. However, a conductive film using a material containing chromium and nitrogen has insufficient cleaning resistance (chemical resistance) against acids and alkalis, which causes a problem of an electrostatic chuck due to film reduction. Since it changes in quality and wear resistance deteriorates, it causes an increase in defects of the reflective mask blank and the reflective mask.
Therefore, a material containing tantalum (Ta) having high chemical resistance and high wear resistance has attracted attention as a material for the conductive film.

  In recent years, the required level of pattern position accuracy for a transfer mask such as a reflective mask has become particularly strict. Particularly, in the case of a reflective mask for EUV lithography (also simply referred to as “reflective mask”), it is used for the purpose of forming a very fine pattern as compared with the prior art, and therefore the required level of pattern position accuracy is further increased. Strict. As one element for realizing high pattern position accuracy, the flatness of a reflective mask blank for EUV lithography (also simply referred to as “reflective mask blank”), which is an original for producing a reflective mask, is improved. Can be mentioned. In order to improve the flatness of the reflective mask blank, first, it is necessary to improve the flatness of the main surface of the glass substrate on the side where the multilayer reflective film is formed. Manufacture of a glass substrate for manufacturing a reflective mask blank starts from manufacturing a glass ingot and cutting it into the shape of the glass substrate. The glass substrate immediately after being cut out has poor main surface flatness and a rough surface. For this reason, a multi-step grinding process and polishing process are performed on the glass substrate, and the surface is finished with high flatness and good surface roughness (mirror surface). In addition, after the polishing process using the abrasive grains, cleaning with a cleaning solution containing a hydrofluoric acid solution or a silicic hydrofluoric acid solution is performed. Further, cleaning with a cleaning solution containing an alkaline solution may be performed before the step of forming a thin film such as a multilayer reflective film.

  However, that alone is not sufficient to produce a reflective mask blank with high flatness. When the film stress of the thin film for forming the pattern formed on the main surface and the back surface of the glass substrate is high, the substrate is deformed, and the flatness changes with time. For this reason, various measures have been taken during film formation or after film formation in order to reduce the film stress of the thin film for forming the pattern. Until now, reflective mask blanks that have been adjusted to achieve high flatness by taking these measures should be stored in a sealed case even if they are stored for a relatively long period of time (for example, about half a year) after manufacturing. It was thought that the flatness would not change greatly. However, in the case of a reflective mask blank in which a material containing tantalum is used for the conductive film formed on the back surface, the flatness of the main surface changes as time elapses even if it is hermetically stored in the case. It has been confirmed that Specifically, with the passage of time, there is a problem of stress aging, such that the flatness of the main surface on the side where the conductive film is formed changes in a direction in which the tendency of the convex shape increases.

  The occurrence of the stress aging problem means that when the glass substrate is not the cause, the film stress of the conductive film gradually increases the tendency of compressive stress.

  As described above, from the viewpoint of improving the wear resistance and chemical resistance of the conductive film during electrostatic chucking, a reflective type using a conductive film made of a material containing tantalum having relatively high hardness and high acid or alkali chemical resistance. Mask blanks have been tried, but in the case of a reflective mask blank using a conductive film made of a material containing tantalum, a new problem is that it is difficult to guarantee pattern position accuracy in an EUV mask because of the change in stress over time. Has occurred. From the above, this phenomenon that occurs in the reflective mask blank using a material containing tantalum in the conductive film is not due to the deformation of the glass substrate itself, but the compressive stress of the conductive film over time. It is assumed that it will grow.

  In recent years, there has been an attempt to hide the defect under the absorber film pattern by using the defect position information of the reflective mask blank. There arises a problem that the positional accuracy cannot be guaranteed. Furthermore, even when a reflective mask is manufactured in a short period of time after manufacturing a reflective mask blank, there is also a problem that pattern displacement occurs over time after the manufacturing.

  The present invention has been made under such circumstances. In a reflective mask blank for EUV lithography and a reflective mask for EUV lithography using a material containing tantalum as the conductive film, the film stress of the conductive film is time-dependent. It is an object of the present invention to provide a reflective mask blank and a reflective mask for solving the problem that the tendency of compressive stress becomes stronger as time passes. Another object of the present invention is to provide a method for manufacturing a semiconductor device with few defects by using the reflective mask for EUV lithography.

  The present invention has the following configurations 1 to 6, a method for manufacturing a substrate with a multilayer reflective film for EUV lithography, a method for manufacturing a reflective mask blank for EUV lithography of configuration 7, and a reflection for EUV lithography of configuration 8 This is a method for manufacturing a mold mask and a method for manufacturing a semiconductor device having configuration 9.

(Configuration 1)
In the manufacturing method of Configuration 1 of the present invention, a multilayer reflective film that reflects EUV light is formed on a glass substrate, and a conductive film is formed on the surface opposite to the surface on which the multilayer reflective film is provided. A method for producing a reflective mask blank for EUV lithography, wherein at least thermal energy or light energy is applied to the glass substrate to desorb hydrogen contained in the glass substrate, and then tantalum is contained. And a method for producing a substrate with a multilayer reflective film for EUV lithography, comprising forming a conductive film made of a material substantially free of hydrogen.

  The glass substrate is incorporated into the surface layer or inside of the glass substrate by performing a process of applying thermal energy (referred to as “heating process”) or a process of applying optical energy (referred to as “light irradiation process”). OH groups, hydrogen, water, etc. that are present can be forced out. Therefore, by using the substrate with a multilayer reflective film for EUV lithography of Configuration 1, the problem that the film stress of the conductive film becomes more compressive stress over time is solved, and the flatness changes with time. It is possible to obtain a reflective mask blank for EUV lithography and a reflective mask for EUV lithography that suppresses the above.

(Configuration 2)
In the production method of Configuration 2 of the present invention, the application of the thermal energy is a heat treatment in which the glass substrate is heated to 150 ° C. or higher. The substrate with a multilayer reflective film for EUV lithography according to Configuration 1 It is a manufacturing method. By the predetermined heat treatment for the glass substrate, hydrogen can be sufficiently removed from the glass substrate.

(Configuration 3)
In the manufacturing method of Configuration 3, the application of the light energy is a light irradiation process using light including a wavelength of 1.3 μm or more. The substrate with a multilayer reflective film for EUV lithography according to Configuration 1 It is a manufacturing method. Hydrogen can be sufficiently removed out of the glass substrate by a predetermined light irradiation treatment on the glass substrate.

(Configuration 4)
According to a fourth aspect of the present invention, there is provided a method for manufacturing a substrate with a reflective film for EUV lithography according to the third aspect, wherein the light irradiation process is a process of irradiating the glass substrate with light emitted from a halogen heater. Is the method. In the wavelength spectrum of light emitted from the halogen heater, the intensity of light in the infrared region is particularly high compared to the intensity of light in other wavelength regions. For this reason, if the light emitted from the halogen heater is used, the glass substrate can be efficiently heated, and hydrogen can be sufficiently removed outside the glass substrate.

(Configuration 5)
The manufacturing method according to the fifth aspect of the present invention is the method according to any one of the first to fourth aspects, wherein at least a main surface of the glass substrate on the side where the conductive film is formed is mirror-polished. It is a manufacturing method of a substrate with a reflective film for EUV lithography.

  By performing mirror polishing on at least the main surface of the glass substrate on the side where the conductive film is formed, the conditions of high flatness and surface roughness can be satisfied. Therefore, the surface of the conductive film of the reflective mask blank for EUV lithography and the reflective mask for EUV lithography using a substrate with a multilayer reflective film for EUV lithography becomes highly flat and highly smooth. Occurrence can be further suppressed.

(Configuration 6)
The manufacturing method according to Structure 6 of the present invention is any one of Structures 1 to 5 characterized in that a mark serving as a reference for positional information of defects of the mask blank is provided on the side on which the multilayer reflective film is formed. The manufacturing method of the board | substrate with a reflecting film for EUV lithography as described in above. Since the substrate with a multilayer reflective film of the present invention can suppress the flatness from changing over time, the accuracy of the defect position information can be improved when it has a mark serving as a reference for the defect position information. it can.

(Configuration 7)
In the manufacturing method of Configuration 7 of the present invention, an absorber film is formed on the multilayer reflective film of the substrate with the multilayer reflective film for EUV lithography obtained by the manufacturing method according to any one of Configurations 1 to 6. Is a method of manufacturing a reflective mask blank for EUV lithography. By using a reflective mask blank for EUV lithography provided with an absorber film, a reflective mask for EUV lithography having an absorber film pattern can be obtained. The reflective mask blank for EUV lithography can further have a thin film such as a resist film for patterning the absorber film on the absorber film.

(Configuration 8)
The manufacturing method according to Configuration 8 of the present invention is characterized in that the absorber film in the reflective mask blank for EUV lithography according to Configuration 7 is patterned to form an absorber film pattern on the multilayer reflective film. , A manufacturing method of a reflective mask for EUV lithography. By forming the absorber film pattern on the absorber film, a reflective mask for EUV lithography having the absorber film pattern can be obtained. As a result, a reflective mask for EUV lithography for manufacturing a semiconductor device with few defects can be obtained.

(Configuration 9)
According to a ninth aspect of the present invention, there is provided a semiconductor device characterized in that a transfer pattern is exposed and transferred onto a resist film on a semiconductor substrate using the reflective mask obtained by the reflective mask manufacturing method according to the eighth aspect. It is a manufacturing method. By using the reflective mask of the present invention, a method for manufacturing a semiconductor device with few defects can be obtained.

  According to the present invention, in a substrate with a multilayer reflective film for EUV lithography, a reflective mask blank for EUV lithography and a reflective mask for EUV lithography using a material containing tantalum as the conductive film, the film stress of the conductive film is To provide a substrate with a multilayer reflective film for EUV lithography, a reflective mask blank for EUV lithography, and a reflective mask for EUV lithography, in which the flatness is suppressed from changing due to the tendency of compressive stress to increase over time. it can. In addition, by using the reflective mask for EUV lithography of the present invention for manufacturing a semiconductor device, it is possible to manufacture a semiconductor device having a fine and high-precision circuit pattern on a semiconductor substrate. A method for manufacturing a semiconductor device with a small amount of the semiconductor device can be obtained.

  In the substrate with a multilayer reflective film for EUV lithography and the reflective mask blank for EUV lithography of the present invention, it is possible to suppress the tendency of the film stress of the conductive film containing tantalum to increase in compressive stress over time. Therefore, according to the present invention, it is possible to obtain a substrate with a multilayer reflective film for EUV lithography and a reflective mask blank that can suppress the change in flatness over time after production. Therefore, in the substrate with a multilayer reflective film for EUV lithography and the reflective mask blank for EUV lithography of the present invention, the film stress level of the conductive film during production can be maintained. If the substrate with a multilayer reflective film for EUV lithography and the reflective mask blank for EUV lithography of the present invention are used, the pattern of the pattern generated when a reflective mask is produced from a reflective mask blank having a conductive film having a high film stress. Large displacement can be suppressed. Further, when a reflective mask for EUV lithography is produced from a substrate with a multilayer reflective film for EUV lithography and a reflective mask blank for EUV lithography produced by the production method of the present invention, the position of the pattern with the passage of time after production. It is also possible to suppress the occurrence of deviation. Furthermore, the resist film on the semiconductor substrate is applied to the resist film on the semiconductor substrate by using a reflective mask for EUV lithography in which the change in flatness of the main surface due to the film stress of the conductive film is suppressed and the positional deviation of the pattern formed on the conductive film is also suppressed. Transfer patterns can be transferred. As a result, a semiconductor device having a fine and highly accurate circuit pattern on the semiconductor substrate can be manufactured.

It is a cross-sectional schematic diagram which shows an example of a structure of the reflective mask blank concerning embodiment of this invention. It is a cross-sectional schematic diagram which shows an example of a structure of the reflective mask concerning embodiment of this invention. It is a cross-sectional schematic diagram which shows an example of the process until it manufactures a reflective mask from the reflective mask blank concerning embodiment of this invention. It is a schematic diagram which shows schematic structure of the pattern transfer apparatus carrying a reflective mask. It is a schematic diagram which shows the glass substrate which can be used for the reflective mask blank of this invention. It is a figure which shows the structure of the optical heating apparatus for light-irradiating the glass substrate concerning embodiment of this invention.

  In the present invention, a multilayer reflective film 12 that reflects EUV light is formed on a glass substrate 11, and a conductive film 18 is formed on the surface opposite to the surface on which the multilayer reflective film 12 is provided. This is a manufacturing method of a substrate with a multilayer reflective film for EUV lithography and a reflective mask blank 1 for EUV lithography in which an absorber film 16 is formed on the multilayer reflective film 12. The conductive film 18 is a thin film made of a material containing tantalum and substantially no hydrogen.

  The reflective mask blank 1 for EUV lithography may have a conductive film 18 for promoting electrostatic chucking on the surface (back surface) of the glass substrate 11 on the side opposite to the multilayer reflective film 12 is formed. is there. As a result of repeated verification of defects generated in the reflective mask blank 1, the inventors of the present invention have a tendency that the film stress of the conductive film 18 containing tantalum has a tendency to compressive stress with time. I got the knowledge that it will be.

  Therefore, the present inventors have conducted intensive research on the cause of the compressive stress of the conductive film 18 containing tantalum immediately after film formation on the glass substrate 11 with the passage of time. First, in order to confirm whether there is a cause in the storage method of the glass substrate with a conductive film after the conductive film 18 is formed, it has been verified with various storage cases and storage methods. The flatness of the main surface 71 of the substrate changed with time, and no clear correlation was obtained. Next, heat treatment was performed using a hot plate on a glass substrate with a conductive film in which the flatness of the main surface 71 changed in the convex direction. The heat treatment was performed at 200 ° C. for about 5 minutes. When this heat treatment was performed, the convex shape of the main surface 71 temporarily changed in a slightly better direction. However, it has been found that the flatness of the main surface 71 of the glass substrate with a conductive film changes again as time passes after the heat treatment, which does not lead to a fundamental solution.

  The “main surface 71” of the glass substrate 11 refers to the surface excluding the peripheral edge (side surface 72 and chamfered surface 73) of the glass substrate 11, as illustrated in FIG. That is, the “main surface 71” of the glass substrate 11 refers to a surface shown as two “main surfaces 71” facing each other in FIG.

Next, the present inventors examined the possibility that the material containing tantalum is related to the property of easily taking in hydrogen. That is, it was hypothesized that hydrogen is gradually taken into the conductive film 18 containing tantalum with the passage of time, and the compressive stress increases. However, the glass substrate with a conductive film in which the phenomenon that the compressive stress increases with the lapse of time has not been found to cause hydrogen uptake in the conventional knowledge. The glass substrate 11 used for the glass substrate with a conductive film is made of a glass material such as synthetic quartz glass or SiO ₂ —TiO ₂ glass having a low thermal expansion characteristic, and hydrogen is taken into the glass material. It is.

  In order to confirm whether or not hydrogen was taken into the conductive film 18 containing tantalum after the film formation was completed, the following verification was performed. Specifically, for a glass substrate with a conductive film provided with a conductive film 18 made of a material containing tantalum, the film is housed in a case and has not been passed for about two weeks. And a glass substrate with a conductive film in which no change in flatness is observed, and four months have passed since the film was formed and housed in a case, and the flatness changes due to an increase in compressive stress of the conductive film 18 (glass For each glass substrate with a conductive film in which the flatness in Coordinate TIR in a square inner region with a side of 142 mm with respect to the center of the main surface 71 of the substrate 11 is about 300 nm). The film composition was analyzed. For membrane analysis, HFS / RBS analysis (hydrogen forward scattering analysis / Rutherford backscattering analysis) was used. As a result, the hydrogen content in the conductive film 18 of about two weeks after the film formation was below the lower limit of detection, whereas the conductive film 18 after 4 months of film formation had 6% hydrogen. It was found that the content was about atomic%.

  From these results, it was confirmed that the film stress was changed by hydrogen being taken into the tantalum-containing thin film after film formation. Next, the present inventors suspected the glass substrate 11 as a hydrogen generation source. Therefore, the inventors prepared a substrate that was further subjected to heat treatment after polishing until the flatness and surface roughness of the main surface were equal to or higher than the level required for the glass substrate 11 for the mask blank. Then, a thin film made of a material containing tantalum was formed and verified in the same manner as described above. As a result, in the case of a mask blank using a substrate subjected to heat treatment, even when 4 months have elapsed after film formation, the degree of deterioration of flatness was small, and the hydrogen content in the film was also suppressed.

  Moreover, the present inventors tried light irradiation treatment instead of heat treatment. That is, the present inventors polished until the flatness and surface roughness of the main surface 71 are equal to or higher than the level required for the glass substrate 11 for mask blank, and then the light including the wavelength in the infrared region. The glass substrate 11 subjected to the light irradiation treatment for irradiating the film was prepared, a thin film made of a material containing tantalum was formed, and the same verification as described above was performed. As a result, even in the case of a mask blank using the glass substrate 11 that has been subjected to light irradiation treatment, and after four months have passed since film formation, the degree of change in flatness is small and the hydrogen content in the film is also suppressed. It was.

  In addition to the glass material, the following possibilities are conceivable as factors for the presence of OH groups, hydrogen, water, and the like serving as hydrogen generation sources on the glass substrate 11 of the glass substrate with a conductive film.

  Usually, the conditions of the flatness and surface roughness of the main surface 71 required for the glass substrate 11 used in the reflective mask blank 1 are strict, and the reflective mask remains in a state cut out from the glass ingot into the shape of the glass substrate 11. It is difficult for the glass substrate 11 for the blank 1 to satisfy the condition. It is necessary to perform a grinding process and a polishing process in a plurality of stages on the cut glass substrate 11 to finish the main surface 71 with high flatness and surface roughness. Further, the polishing liquid used in the polishing step contains colloidal silica abrasive grains as an abrasive. Since colloidal silica abrasive grains are likely to adhere to the surface of the glass substrate 11, a cleaning solution containing hydrofluoric acid or silicic acid having an action of etching the surface of the glass substrate 11 is used during or after a plurality of polishing steps. Washing is also usually done.

  In the grinding process or the polishing process, a work-affected layer is likely to be formed on the surface layer of the glass substrate 11, and OH groups and hydrogen may be taken into the work-affected layer. At this time, OH groups and hydrogen may be further taken into the glass substrate 11 from the work-affected layer. There is a possibility that OH groups and hydrogen are taken in even when the surface of the glass substrate 11 is finely etched during cleaning such as during the polishing process. Furthermore, a hydration layer may be formed on the surface of the glass substrate 11.

  The present invention has been made in consideration of the above. That is, according to the present invention, a multilayer reflective film 12 that reflects EUV light is formed on a glass substrate 11, and a conductive film 18 is formed on the surface opposite to the surface on which the multilayer reflective film 12 is provided. And a reflective mask blank 1 for EUV lithography in which an absorber film 16 is formed on the multilayer reflective film 12. In the production method of the present invention, the glass substrate 11 is subjected to at least heat energy treatment (referred to as “heating treatment”) or light energy treatment (referred to as “light irradiation treatment”), thereby producing glass. After the hydrogen contained in the substrate 11 is desorbed, the conductive film 18 made of a material containing tantalum and substantially not containing hydrogen is formed. By heat treatment or light irradiation treatment on the glass substrate 11, OH groups, hydrogen, water, and the like incorporated in the surface layer or inside of the glass substrate 11 can be forcibly removed. By forming the conductive film 18 containing tantalum on the glass substrate 11 after performing the heat treatment or the light irradiation treatment, it is possible to suppress the incorporation of hydrogen into the conductive film 18 containing tantalum, An increase in the compressive stress of the conductive film 18 can be suppressed.

  FIG. 1 is a schematic cross-sectional view of an example of a reflective mask blank 1 of the present invention, and FIG. 2 is a schematic cross-sectional view of an example of a reflective mask 2 obtained by the present invention. FIG. 3 is a schematic cross-sectional view showing an example of a schematic process according to the method for manufacturing the reflective mask 2 of the present invention. In the substrate with a multilayer reflective film and the reflective mask blank 1 of the present invention, a multilayer reflective film 12 that reflects EUV light is formed on a glass substrate 11. The substrate with a multilayer reflective film for EUV lithography referred to in the present invention is one in which a multilayer reflective film 12 that reflects EUV light is formed on a glass substrate 11. The substrate with a multilayer reflective film for EUV lithography according to the present invention includes a multilayer reflective film 12 that reflects EUV light on a glass substrate 11, and a multilayer reflective film on the multilayer reflective film 12 when an absorber film pattern is formed. Also included are those formed with a protective film 13 (capping layer) for protecting the film 12. Further, the substrate with a multilayer reflective film for EUV lithography according to the present invention has a multilayer reflective film in the case where a mark serving as a reference for positional information of defects to be described later is formed on the multilayer reflective film 12 or the protective film 13 by a lithography process. 12 and a film in which a resist film 19 is formed on the protective film 13.

  An example of the reflective mask blank 1 used in the manufacturing method of the reflective mask 2 of the present invention is configured as shown in FIG. That is, in the example of FIG. 1, a multilayer reflective film 12 that reflects exposure light in a short wavelength region including the EUV region on the glass substrate 11 in order, a multilayer reflective film at the time of absorber film pattern formation and absorber film pattern correction 12, and an absorber film 16 that absorbs exposure light in a short wavelength region including the EUV region. In this embodiment, the absorber film 16 includes a lower layer and an EUV region. This is a reflective mask blank 1 having a two-layer structure in which an exposure light absorber layer 14 in a short wavelength region is used and an upper layer is a low reflection layer 15 for inspection light used for inspection of an absorber film pattern.

  As shown in FIG. 2, the reflective mask 2 obtained by the present invention has a pattern in the absorber film 16 (that is, the low reflective layer 15 and the exposure light absorber layer 14) in the reflective mask blank 1 as described above. It is formed in a shape. In the reflective mask 2 including the absorber film 16 having the laminated structure as described above, the absorber film 16 on the mask surface includes a layer that absorbs exposure light and a layer that has a low reflectance with respect to the mask pattern inspection wavelength. Further, by separating the functions from each other and forming a laminated structure, a sufficient contrast at the time of mask pattern inspection can be obtained.

  The reflective mask 2 obtained by the present invention is used for lithography using light in a short wavelength region including an EUV light region in order to enable transfer of a finer pattern exceeding the transfer limit by the conventional photolithography method. And can be used as a reflective mask 2 for EUV exposure light.

  Next, the manufacturing method of the board | substrate with a multilayer reflective film for EUV lithography of this invention is demonstrated.

As the substrate 11 used for the substrate with a multilayer reflective film for EUV lithography according to the present invention, the glass substrate 11 can be preferably used since good smoothness and flatness can be obtained. Specifically, as the material of the substrate 11, the synthetic quartz glass, and low thermal expansion of _SiO 2 -TiO ₂ type glass (2-way system having the characteristics _(SiO 2 -TiO ₂₎ and ternary _(SiO 2 -TiO ₂ -SnO ₂ etc.), for example, SiO ₂ -Al ₂ O ₃ -Li ₂ O-based crystallized glass, crystallized glass on which β-quartz solid solution is precipitated, and the like.

  The glass 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 a high reflectance and transfer accuracy. In addition, unit Rms which shows smoothness in this invention is a root mean square roughness, and can be measured with an atomic force microscope. Further, the flatness in the present invention is a value indicating the surface warpage (deformation amount) indicated by TIR (total indicated reading). This is because when the plane determined by the least square method based on the surface of the glass substrate 11 is a focal plane, the highest position of the surface of the glass substrate 11 above the focal plane and the lowest position below the focal plane. The absolute value of the height difference at a low position. Smoothness is indicated by smoothness in a 10 μm square area, and flatness is indicated by flatness in a 142 mm square area.

  In the method for producing a substrate with a multilayer reflective film for EUV lithography according to the present invention, it is preferable that at least the main surface 71 of the glass substrate 11 on the side where the conductive film 18 is formed is mirror-polished. In the glass substrate 11 cut out from the glass ingot, the high flatness and surface roughness conditions as described above cannot be satisfied. In order to satisfy the conditions of high flatness and surface roughness, it is essential to perform mirror polishing on at least the main surface 71 of the glass substrate 11. By performing mirror polishing on the main surface 71 of the glass substrate 11, it is possible to satisfy the conditions of high flatness and surface roughness.

  In this mirror polishing, it is preferable that both main surfaces 71 of the glass substrate 11 are simultaneously polished by double-side polishing with a polishing liquid containing colloidal silica abrasive grains. Moreover, it is preferable to finish to the main surface 71 which satisfy | fills the calculated | required flatness and surface roughness by performing a grinding process and a grinding | polishing process in multiple steps with respect to the glass substrate 11 of the cut-out state. In this case, it is preferable to use a polishing liquid containing abrasive grains of colloidal silica at least in the final stage of the polishing process.

  After the glass substrate 11 is mirror-polished, it is desirable to clean the glass substrate 11 by a predetermined cleaning process before performing heat treatment or light irradiation treatment. If the heat treatment or the like is performed with the abrasive grains used in the polishing step attached, the surface is fixed to the surface of the glass substrate 11 and may not be removed even if a normal cleaning step is performed after the heat treatment or the like. In particular, in the case of a material similar to the glass substrate 11 such as colloidal silica, there is a possibility that the material adheres firmly to the surface of the glass substrate 11. It is desirable to wash with a cleaning solution containing an acid.

  In the method for producing a substrate with a multilayer reflective film for EUV lithography of the present invention, at least thermal energy is applied to the glass substrate 11 that satisfies the conditions as the mask blank substrate 11 after mirror polishing is performed in the polishing step. Is performed (referred to as “heating treatment”) or light energy is applied (referred to as “light irradiation treatment”), and hydrogen contained in the glass substrate 11 is desorbed. In the manufacturing method of the present invention, both the heat treatment and the light irradiation treatment can be performed on the glass substrate 11 described above.

  Next, the heat treatment for the glass substrate 11 will be described.

The heat treatment performed on the glass substrate 11 is preferably a treatment for heating the glass substrate 11 to 150 ° C. or higher. In the heat treatment at less than 150 ° C., the temperature is insufficient, so that the effect of discharging the hydrogen in the glass substrate 11 out of the glass substrate 11 cannot be sufficiently obtained. When the heat treatment is 200 ° C. or higher, the effect is more obtained, more preferably 300 ° C. or higher, more preferably 400 ° C. or higher, and particularly preferably 500 ° C. or higher. A sufficient effect of eliminating the substrate 11 can be obtained. Further, the heat treatment for the glass substrate 11 needs to be lower than the softening point temperature of the material of the glass substrate 11. This is because the glass substrate 11 is softened and deformed when the temperature is not lower than the softening point temperature. Regarding the softening point of the glass material, for example, the softening point of SiO ₂ —TiO ₂ glass is 1490 ° C., and the softening point of synthetic quartz glass is 1600 ° C. In order to reliably avoid deformation due to softening of the glass substrate 11, it is preferable to perform the heat treatment at a temperature somewhat lower than the softening point of the glass material. Specifically, the temperature of the heat treatment for glass such as SiO ₂ —TiO ₂ glass and synthetic quartz glass is preferably 1200 ° C. or less, more preferably 1000 ° C. or less, and still more preferably 800 ° C. or less. The treatment time of the heat treatment is preferably at least 5 minutes, more preferably 10 minutes or more, and even more preferably 30 minutes or more, although it depends on the heating temperature.

  The heat treatment is preferably performed in a state where a gas from which hydrogen is excluded as much as possible exists around the glass substrate 11. Although the amount of hydrogen itself is small in the air, a large amount of water vapor is present. Although the humidity in the air in the clean room is controlled, a relatively large amount of water vapor is present. By performing the heat treatment on the glass substrate 11 in dry air, entry of hydrogen due to water vapor into the glass substrate 11 can be suppressed. Furthermore, it is more preferable that the glass substrate 11 is heat-treated in a gas not containing hydrogen or water vapor (an inert gas such as nitrogen or a rare gas). The heat treatment of the glass substrate 11 can also be performed in a vacuum.

  Next, the light irradiation process with respect to the glass substrate 11 is demonstrated.

  The light irradiation treatment is preferably performed in a state where a gas from which hydrogen is excluded as much as possible exists around the glass substrate 11. Although the amount of hydrogen itself is small in the air, a large amount of water vapor is present. Although the humidity in the air in the clean room is controlled, a relatively large amount of water vapor is present. By performing the heat treatment on the glass substrate 11 in dry air, entry of hydrogen due to water vapor into the glass substrate 11 can be suppressed. Furthermore, it is more preferable that the glass substrate 11 is heat-treated in a gas not containing hydrogen and water vapor (an inert gas such as nitrogen and a rare gas). The light irradiation treatment can be performed in a gas at atmospheric pressure or in a vacuum. In order to reduce OH groups, hydrogen, water, and the like taken into the surface layer and the inside of the glass substrate 11 with certainty, it is preferable that the surroundings of the glass substrate 11 to be subjected to the light irradiation treatment have a certain degree of vacuum. The degree of vacuum is more preferably a medium vacuum (0.1 Pa to 100 Pa).

  The light used for the light irradiation treatment is preferably light having a wavelength of 1.3 μm or more. Since the light emitted from the halogen heater 46 is light including a wavelength of 1.3 μm or more, specifically, the light irradiation process is preferably a process of irradiating the glass substrate 11 with light emitted from the halogen heater 46. .

  The wavelength spectrum of light emitted from the halogen heater 46 is light that has a particularly high intensity of light in the infrared region as compared with the intensity of light in other wavelength regions, and includes a wavelength of 1.3 μm or more. For this reason, the glass substrate 11 can be efficiently heated by the light emitted from the halogen heater 46, and hydrogen can be sufficiently removed out of the glass substrate 11. The light emitted from the halogen heater 46 is multicolor light including a plurality of wavelengths. As described above, the glass substrate 11 containing OH groups, water, and the like has significant absorption bands at wavelengths of 1.38 μm, 2.22 μm, and 2.72 μm. Therefore, it is preferable that the light emitted from the halogen heater 46 has a sufficiently strong intensity at wavelengths of 1.38 μm, 2.22 μm, and 2.72 μm. That is, the light used for the light irradiation treatment is preferably light including a wavelength of 1.3 μm or more. Considering this condition, the halogen heater 46 used for the light irradiation treatment preferably has a color temperature of 2200K or higher, and preferably 3400K or lower.

  The wavelength of the light irradiation treatment condition is not particularly limited as long as it has energy capable of desorbing hydrogen contained in the glass substrate 11. For example, in the vacuum ultraviolet region, the far ultraviolet region, the near ultraviolet region, the visible region, the near infrared region, the mid infrared region, the far polar ultraviolet region, or a wavelength region extending over a plurality of regions selected from these wavelength regions Good. Typical examples of the light source that emits light over a wide range from the near infrared to the mid infrared to the far infrared include the halogen heater 46, and the wide range from the far ultraviolet to the mid infrared with a focus on the near ultraviolet to the visible. As a light source that emits light over a range, a xenon flash lamp, as a light source that emits light from near ultraviolet to visible, high pressure UV lamp, metal halide lamp, rare gas fluorescent lamp, from vacuum ultraviolet to near ultraviolet As a light source that emits light, a low-pressure UV lamp or a dielectric barrier discharge excimer lamp can be used. In particular, when the glass substrate 11 is irradiated with light energy and the glass substrate 11 is heated to desorb hydrogen, it is preferable to irradiate infrared light. Specifically, it is preferable to use light having a wavelength of 1.3 μm or more, and specifically, it is preferable to use a halogen heater 46.

  The light irradiation time in the light irradiation treatment depends on the wavelength of the light source to be used. For example, in the case of light (halogen heater 46) including a wavelength of 1.3 μm or longer, it is preferably 1 minute or longer. Is preferably 5 minutes or more and 10 minutes or more.

  In this light irradiation treatment, a light heating device 40 as shown in FIG. 6 can be used. The light heating device 40 has a main configuration including a mounting table 44 on which the light source unit 42 and the glass substrate 11 are mounted in a processing chamber 41. The light source unit 42 can have a structure in which a plurality of cylindrical halogen heaters 46 are arranged in parallel in two upper and lower stages on a unit frame 45. The upper and lower halogen heaters 46 can be arranged in a lattice shape when viewed from above. With such a configuration of the light source unit 42, the main surface 71 of the glass substrate 11 can be irradiated with light in the infrared region almost uniformly. In addition, as the light heating device 40, for example, a device having a structure in which the halogen heater 46 is used in place of the incandescent lamp in the light heating device 40 described in Patent Document 5 can be used.

  A reflection plate 47 can be provided on the surface of the unit frame 45 above the upper halogen heater 46. Thereby, infrared light emitted upward from the halogen heater 46 is reflected by the reflecting plate 47 and can be irradiated onto the main surface 71 of the glass substrate 11. The mounting table 44 can have a shape having an opening so as to hold the outer peripheral edge of the glass substrate 11. A reflector 48 can also be provided below the opening. In this case, since the light transmitted through the glass substrate 11 is reflected by the reflecting plate 48, the reflected light can be applied to the main surface 71 on the back side of the glass substrate 11.

  In addition, when performing the light irradiation process of the glass substrate 11 in the light heating apparatus 40 in a vacuum, the process chamber 41 can be made into the structure which can be vacuum-processed. In this case, the halogen heater 46 and the like can be disposed in the vacuum atmosphere inside the processing chamber 41. Also, a structure in which the halogen heater 46 or the like is disposed at a location open to atmospheric pressure so that light from the halogen heater 46 is transmitted through a transparent window capable of being vacuum-tight and incident on the processing chamber 41 under vacuum. It can be. It is preferable that the transparent window used in this structure has a high transmittance with respect to the light having the predetermined wavelength.

  In the method of manufacturing a substrate with a multilayer reflective film for EUV lithography, a multilayer reflective film 12 that reflects EUV light is formed on the main surface 71 of the glass substrate 11 for the manufacture of a mask blank after heat treatment or light irradiation treatment. Is done. A conductive film 18 is formed on the surface opposite to the surface on which the multilayer reflective film 12 is provided. In forming these thin films, a film forming apparatus using a vacuum such as a sputtering apparatus is usually used. For example, when the heat treatment and the light irradiation treatment are performed in a vacuum, in order to avoid absorption of hydrogen by the glass substrate 11 and contamination of the surface of the glass substrate 11, an apparatus and a film formation apparatus for the heat treatment and the light irradiation treatment are: It is preferable that the glass substrate 11 be connected so that it can be conveyed while maintaining the degree of vacuum. In addition, when it is necessary to expose the glass substrate 11 after the light irradiation treatment to an atmospheric pressure due to the structure of the apparatus, it is possible to take as much time as possible after the heat treatment and the light irradiation treatment until a thin film is formed by the film formation apparatus. A short time is preferable.

  In order to manufacture a substrate with a multilayer reflective film for EUV lithography, the multilayer reflective film 12 that reflects EUV light is formed on the main surface 71 of the glass substrate 11 after the above heat treatment and light irradiation treatment.

  The multilayer reflective film 12 formed on the main surface 71 of the glass substrate 11 is made of a material that reflects exposure light in a short wavelength region including the EUV region. It is particularly preferable that the multilayer reflective film 12 is made of a material having a very high reflectance with respect to light in a short wavelength region such as EUV light because the contrast when used as the reflective mask 2 can be increased. For example, the multilayer reflective film 12 for EUV light, which is a soft X-ray region of about 12 to 14 nm, is typically a periodic laminated film in which thin films of silicon (Si) and molybdenum (Mo) are alternately laminated. Usually, these thin films (thickness of about several nm) are repeatedly laminated for 40 to 60 periods (number of layers) to form the multilayer reflective film 12. Examples of other multilayer reflective films used in the EUV light region include Ru / Si periodic multilayer reflective films, Mo / Be periodic multilayer reflective films, Mo compound / Si compound periodic multilayer reflective films, and Si / Nb periodic multilayer reflective films. Examples thereof include a film, a Si / Mo / Ru periodic multilayer reflective film, a Si / Mo / Ru / Mo periodic multilayer reflective film, and a Si / Ru / Mo / Ru periodic multilayer reflective film. The multilayer reflective film 12 is formed using, for example, an ion beam sputtering method or a magnetron sputtering method.

  The substrate with a multilayer reflective film of the present invention has a structure in which the conductive film 18 is formed on the main surface 71 (referred to as “back surface”) opposite to the main surface 71 of the glass substrate 11 on which the multilayer reflective film 12 is provided. Have The substrate with a multilayer reflective film of the present invention includes the case where the conductive film 18 is formed not only on the back surface of the glass substrate 11 but also on the chamfered surface 73 in contact with the back surface. Furthermore, the case where it forms to at least one part of the side surface 72 which contact | connects the chamfering surface 73 is also included. FIG. 5 illustrates a side surface 72 and a chamfered surface 73 of the glass substrate 11.

  Since the conductive film 18 is a material that contains tantalum and does not substantially contain hydrogen, the wear resistance and chemical resistance of the conductive film 18 during electrostatic chucking can be improved.

  Since tantalum has a characteristic of becoming brittle when hydrogen is taken in, it is desired to suppress the hydrogen content even immediately after the conductive film 18 made of a material containing tantalum is formed. For this reason, in the board | substrate with a multilayer reflective film of this invention, the conductive film 18 formed on the main surface 71 of the glass substrate 11 selects the material which contains a tantalum and does not contain hydrogen substantially. “Substantially no hydrogen” means that the hydrogen content in the conductive film 18 is at least 5 atomic% or less. The preferable range of the hydrogen content in the conductive film 18 is preferably 3 atomic% or less, and more preferably the detection lower limit value or less.

  The material that contains tantalum that forms the conductive film 18 provided on the glass substrate 11 and that does not substantially contain hydrogen is selected from, for example, tantalum metal, tantalum, nitrogen, oxygen, boron, and carbon. Examples thereof include a material containing one or more elements and substantially not containing hydrogen. Specifically, the conductive film 18 is one kind of thin film selected from Ta, TaN, TaO, TaON, TaB, TaBN, TaBO, TaBON, TaSi, TaSiN, TaSiO and TaSiON, or a plurality of two or more kinds of thin films. Can be. In order to improve wear resistance and suppress the generation of particles, the conductive film 18 preferably has an amorphous structure with high surface smoothness. In addition, the above-mentioned material can contain metals other than tantalum as long as the effects of the present invention are obtained.

  The conductive film 18 of the substrate with a multilayer reflective film of the present invention can contain a material containing tantalum and nitrogen and substantially not containing hydrogen. By containing nitrogen in tantalum, oxidation of tantalum in the conductive film 18 can be suppressed.

From the viewpoint of wear resistance and chemical resistance, TaBN and / or TaN are preferably used as the material of the conductive film 18, and TaBN / Ta ₂ O ₅ or TaN / Ta ₂ O ₅ is more preferably used. The conductive film 18 may be a single layer, or may be a plurality of layers and a composition gradient film.

  In the case where the conductive film 18 is a TaB thin film, the composition ratio preferably includes 5 to 25 atomic% of B and the balance is Ta. When the conductive film 18 is TaBN, it is preferable that the composition ratio includes 5 to 25 atomic% B, 5 to 40 atomic% N, and the balance is Ta. The composition ratio in the case where the conductive film 18 is TaN preferably includes 5 to 40 atomic% of N and the balance is Ta. The composition ratio in the case where the conductive film 18 is TaO preferably includes 1 to 20 atomic% of O and the balance is Ta.

  In addition to tantalum, there is a metal having a property of easily taking in hydrogen. However, when tantalum in the material of the conductive film 18 is replaced with another metal having a property of easily taking in hydrogen, the same as in the present invention. An effect is obtained. Examples of other metals having a property of easily incorporating hydrogen include niobium, vanadium, titanium, magnesium, lanthanum, zirconium, scandium, yttrium, lithium, and praseodymium. The same effect can be obtained with an alloy composed of tantalum and two or more metals selected from the group of metals having the property of easily incorporating hydrogen.

  In order for the electrostatic chuck to operate properly, the sheet resistance of the conductive film 18 is preferably 200Ω / □ or less, more preferably 100Ω / □ or less, still more preferably 75Ω / □ or less, and particularly preferably 50Ω / □ or less. be able to. The sheet resistance can be obtained by adjusting the composition and film thickness of the conductive film 18 to obtain the conductive film 18 having an appropriate sheet resistance.

  In addition, the conductive film 18 of the substrate with a multilayer reflective film of the present invention has a highly oxidized layer containing 60 atomic% or more of oxygen from the viewpoint of chemical resistance, and the surface layer of the conductive film 18 (what is the main surface 71 of the glass substrate 11)? It is preferably formed on the surface layer of the conductive film 18 on the opposite side, that is, the surface layer of the conductive film 18 on the side opposite to the hydrogen intrusion suppression film 17. As described above, hydrogen enters not only from the glass substrate 11 but also hydrogen in the gas surrounding the reflective mask blank 1 from the surface of the conductive film 18. The high oxide film on the surface layer of the conductive film 18 has a characteristic that unbonded tantalum metal cannot exist and prevents hydrogen from entering the conductive film 18. Moreover, the highly oxidized layer (tantalum highly oxidized layer) of the material containing tantalum also has excellent chemical resistance and hot water resistance. Due to the high resistance of the high oxide layer, it is possible to maintain a high function of preventing hydrogen from entering.

The tantalum high oxide layer tends to be in a state where TaO bonds, Ta ₂ O ₃ bonds, TaO ₂ bonds and Ta ₂ O ₅ bonds are mixed. As the abundance ratio of Ta ₂ O ₅ bonds increases in a predetermined surface layer in the light shielding film, both chemical resistance and hot water resistance increase, and as the abundance ratio of TaO bonds increases, these characteristics tend to decrease. is there. In the high tantalum oxide layer, the bonding state between tantalum and oxygen in the layer changes depending on the oxygen content in the layer. That is, when the oxygen content in the high tantalum oxide layer is 60 atomic% or more, not only “Ta ₂ O ₅ ” which is the most stable bonding state but also “Ta ₂ O ₃ ” and “TaO ₂ ”. The combined state is also included. Further, when the oxygen content in the layer is 60 atomic% or more, at least the most unstable TaO bond is an extremely small amount that does not affect the chemical resistance. . Therefore, it is considered that the lower limit value of the oxygen content in the layer is preferably 60 atomic%. In addition, when the oxygen content in the high tantalum oxide layer is 68 atomic% or more, it is considered that not only TaO ₂ bonds are mainly composed but also the ratio of Ta ₂ O ₅ bonding states is increased. The lower limit of the oxygen content is preferably 68 atomic%, and more preferably 71.4 atomic%.

The abundance ratio of Ta ₂ O ₅ bonds in the high tantalum oxide layer is preferably higher than the abundance ratio of Ta ₂ O ₅ bonds in the conductive film 18 excluding the high oxide layer. The Ta ₂ O ₅ bond is a bonded state having very high stability. By increasing the abundance ratio of the Ta ₂ O ₅ bond in the high oxide layer, resistance to mask cleaning such as chemical resistance and hot water resistance can be achieved. Significant increase. In particular, it is most preferable that the high tantalum oxide layer is formed only by a bonded state of Ta ₂ O ₅ . The content of nitrogen and other elements in the high tantalum oxide layer is preferably in a range that does not affect the operational effects such as the property of preventing hydrogen intrusion, and is preferably not substantially contained.

  The thickness of the high tantalum oxide layer is preferably 2 nm or more and 4 nm or less. If it is less than 2 nm, it is too thin to expect the effect of preventing hydrogen intrusion. If the thickness of the high tantalum oxide layer exceeds 4 nm, it will work negatively from the viewpoint of adversely affecting the conductivity of the conductive film 18. In consideration of the balance between the conductivity of the entire conductive film 18, the characteristics of preventing hydrogen intrusion, and the improvement of chemical resistance, the thickness of the highly oxidized layer is more preferably 2 nm or more and 3 nm or less. .

The method for forming a high tantalum oxide layer includes a hot water treatment, an ozone-containing water treatment, a heat treatment in a gas containing oxygen, and an oxygen content for the reflective mask blank 1 after the conductive film 18 is formed. Performing ultraviolet irradiation treatment and / or O ₂ plasma treatment in a gas to be used. The high oxide layer is not limited to the metal high oxide layer forming the conductive film 18. Any metal high-oxidation layer may be used as long as it has a property of preventing hydrogen intrusion, and the high-oxidation layer may be laminated on the surface of the conductive film 18. Further, the material is not necessarily a high oxide as long as the material has a property of preventing hydrogen from entering the conductive film 18, and the material film may be stacked on the surface of the conductive film 18.

  In the method for manufacturing a substrate with a multilayer reflective film for EUV lithography according to the present invention, it is preferable to provide a mark serving as a reference for positional information of defects of the mask blank on the side on which the multilayer reflective film 12 is formed.

  In general, the substrate with a multilayer reflective film for EUV lithography and the reflective mask blank 1 are required to have no defect having a sphere equivalent diameter of about 20 nm or more. However, it is very difficult to manufacture the multilayer reflective film-coated substrate and the reflective mask blank 1 without such very small defects. In the case where a defect exists in the reflective mask blank 1, it has been proposed to provide a mark serving as a reference for defect position information in order to correct the defect. If the position information of the defect is clarified, it is possible to eliminate the adverse effect of the defect by a method such as correcting the defect or exposing the defect so as not to overlap the transfer pattern. Since the substrate with a multilayer reflective film of the present invention can suppress the flatness from changing over time, the accuracy of the defect position information can be improved when it has a mark serving as a reference for the defect position information. it can. The reference mark may be formed anywhere on the side where the multilayer reflective film 12 is formed. For example, it can be formed on any of the main surface 71 of the glass substrate 11, the multilayer reflective film 12, the protective film 13, and the absorber film 16. In addition, the reference mark should be formed by a lithography process, focused ion beam irradiation, laser light irradiation, machining traces scanned with a diamond needle, etc., indentation with a small indenter, or embossing by an imprint method. Can do.

  Next, the manufacturing method of the reflective mask blank 1 for EUV lithography of this invention is demonstrated.

  The present invention is a reflective mask blank 1 for EUV lithography, comprising at least an absorber film 16 on the multilayer reflective film 12 of the substrate with the multilayer reflective film for EUV lithography described above. In FIG. 1, the cross-sectional schematic diagram of an example of the reflective mask blank 1 for EUV lithography of this invention is shown. As shown in FIG. 1, by providing a predetermined absorber film 16 on a multilayer reflective film 12 of a substrate with a multilayer reflective film for EUV lithography according to the present invention, it can be used as a reflective mask blank 1 for EUV lithography. . The reflective mask blank 1 for EUV lithography of the present invention can further have a thin film such as an electron beam drawing resist film 19 for patterning the absorber film on the absorber film 16. That is, the reflective mask blank 1 for EUV lithography of the present invention includes a predetermined absorber film 16 and an electron beam drawing resist film 19 on the multilayer reflective film 12 of the substrate with the multilayer reflective film for EUV lithography of the present invention. Can have different structures.

  In the example of the reflective mask blank 1 shown in FIG. 1, a protective film 13 is formed between the multilayer reflective film 12 and the absorber film 16. Providing the protective film 13 prevents damage to the multilayer reflective film not only during the pattern formation of the absorber film but also during pattern correction, so that the multilayer reflective film can be kept highly reflective. preferable.

  The present invention is characterized in that the pattern of the absorber film 16 (absorber film pattern 22) is formed on the multilayer reflective film 12 by patterning the absorber film 16 of the reflective mask blank 1 for EUV lithography described above. This is a manufacturing method of the reflective mask 2 for EUV lithography. In FIG. 2, the cross-sectional schematic diagram of an example of a structure of the reflective mask 2 of this invention is shown. With reference to FIG. 3, the manufacturing method of the reflective mask 2 of this invention is demonstrated.

  FIG. 3A shows an example of the configuration of the reflective mask blank 1 used in the present invention. The configuration has already been described above. This reflective mask blank 1 is formed on a glass substrate 11 by laminating a multilayer reflective film 12, a protective film 13, an exposure light absorber layer 14, and an inspection light low reflective layer 15 in this order. The reflective mask blank 1 can further have a resist film 19.

  Next, the absorber film 16 including the exposure light absorber layer 14 which is an absorber of the EUV light 31 and the inspection light low reflection layer 15 is processed to form a predetermined absorber film pattern. Usually, an electron beam drawing resist film 19 is applied and formed on the surface of the absorber film 16 to prepare a reflective mask blank 1 with a resist film (FIG. 3B). Next, a predetermined pattern is drawn on the electron beam drawing resist film 19 and developed to form a predetermined resist pattern 21 ((c) in the figure). Next, the absorber film 16 is etched using the resist pattern 21 as a mask, and finally the resist pattern 21 is removed to obtain the reflective mask 2 having the absorber film pattern 22 ((d) in the figure). In the present embodiment, the absorber film 16 has a laminated structure of an exposure light absorber layer 14 constituted by an EUV light 31 absorber and a low reflection layer 15 constituted by an inspection light absorber of a mask pattern. Both are made of a material mainly composed of tantalum (Ta). In the step of etching the absorber film 16, when dry etching is performed using the same etching gas, the etching rate ratio of each layer constituting the absorber film 16 is preferably in the range of 0.1 to 10. Thereby, the etching controllability of the laminated tantalum-based absorber film 16 can be improved, and therefore the in-plane uniformity such as the pattern line width and the degree of damage to the protective film 13 can be improved.

  In the present invention, it is most preferable to use a gas containing fluorine (F) as an etching gas when the absorber film 16 having the above-described laminated structure is dry-etched. When the tantalum-based absorber film 16 having the laminated structure is dry-etched using a gas containing fluorine (F), the etching rate ratio of each layer constituting the absorber film 16 can be controlled to be within the above-described preferable range. Because it can.

Examples of the gas containing fluorine (F) include CF ₄ , CHF ₃ , C ₂ F ₆ , C ₃ F ₆ , C ₄ F ₆ , C ₄ F ₈ , CH ₂ F ₂ , CH ₃ F, and C ₃ F. ₈ , SF ₆ and F and the like. Although such a fluorine-containing gas may be used alone, two or more kinds of mixed gases selected from the above-mentioned fluorine gas, a rare gas such as argon (Ar), or a chlorine (Cl ₂ ) gas is mixed. May be used.

  Either one of the exposure light absorber layer 14 and the low reflection layer 15 constituting the absorber film 16 is made of a material containing tantalum (Ta), boron (B), and oxygen (O), and the other is tantalum ( When the absorber film 16 is dry-etched using a gas containing fluorine in the case where the absorber film 16 is made of a material containing Ta), boron (B), and nitrogen (N), the etching rate of each layer constituting the absorber film 16 is determined. Since the ratio can be controlled to be in the range of 0.15 to 5.0, the present invention is particularly suitable.

  By dry-etching the laminated tantalum-based absorber film 16 using, for example, a gas containing fluorine, the etching rate ratio of each layer constituting the absorber film 16 is in the range of 0.1 to 10, The etching controllability of the absorber film 16 can be improved, and damage to the lower layer when the absorber film 16 is etched can be minimized.

  After the absorber film 16 is etched as described above, the remaining resist pattern is removed by a method such as oxygen ashing.

  When the reflective mask 2 manufactured as described above is exposed to EUV light 31, the protective film 13 is absorbed in a portion where the absorber film 16 is present on the mask surface and exposed in a portion where the other absorber film 16 is removed. In addition, the EUV light 31 is reflected by the multilayer reflective film 12 (see FIG. 4D), and can be used as a reflective mask 2 for lithography using EUV light.

  The reflective mask 2 manufactured by the manufacturing method of the present invention is the reflective mask 2 having the conductive film 18 as described above. Since the reflective mask blank 1 which has been manufactured for a certain period of time or more after being manufactured is restrained from increasing the compressive stress of the conductive film 18 over time, the flatness of the reflective mask blank 1 is at a high level that is required. Maintained. If the reflective mask blank 1 having such characteristics is used, the completed reflective mask 2 can have the required high flatness. Further, since the compressive stress of the conductive film 18 is suppressed, the amount of displacement on the main surface 71 caused by each pattern of the conductive film 18 released from the surrounding compressive stress after the etching process for producing the reflective mask 2. Can also be suppressed.

  On the other hand, when the reflective mask 2 is produced using the reflective mask blank 1 that has not been manufactured since, the reflective mask 2 (conventional reflective mask 2) immediately after being produced by the conventional production method. ) Has the required high flatness. However, when the conventional reflective mask 2 is stored and stored in a mask case without being used thereafter or when it is continuously used after being set in an exposure apparatus, the compressive stress of the conductive film 18 increases. Since the flatness changes with time, each pattern of the conductive film 18 may be largely misaligned. If the reflective mask 2 of the present invention produced using the reflective mask blank 1 produced by the production method of the present invention is used, an increase in the compressive stress of the conductive film 18 over time can be suppressed, so that it is used after production. Even when stored in a mask case without being stored or when it is set in an exposure apparatus and continuously used, the required high flatness can be maintained, and the positional deviation of each pattern of the conductive film 18 can also be maintained. Can be suppressed.

  The present invention is a method for manufacturing a semiconductor device, wherein a transfer pattern is exposed and transferred onto a resist film on a semiconductor substrate using the reflection type mask 2 obtained by the method for manufacturing the reflection type mask 2 described above.

  The present invention is a method for manufacturing a semiconductor device, characterized in that the transfer pattern is exposed and transferred onto a resist film on a semiconductor substrate using the reflective mask 2 described above. A semiconductor device having a highly accurate pattern can be manufactured by exposing and transferring a transfer pattern onto a resist film on a semiconductor substrate using the reflective mask 2 described above. This is because the above-described reflective mask 2 has high flatness and pattern position accuracy required at the time of manufacture. Further, the reflective mask 2 described above is not used after fabrication and is stored in a mask case and stored for a certain period of time, then set in an exposure apparatus and used for exposure transfer, or after the mask is fabricated. Even when it is set in the exposure apparatus and used for exposure transfer, the required high flatness can be maintained, and the displacement of each pattern of the conductive film 18 can be suppressed.

  Hereinafter, the embodiment of the present invention will be described more specifically with reference to examples.

(Samples 1-4 and Comparative Samples 1-3)
First, in order to obtain knowledge about the film stress of the conductive film 18, as samples 1 to 4 and comparative samples 1 to 3, stress aging (flatness change), chemical resistance, and Abrasion evaluation was performed.

  The composition analysis of the thin film of the sample was performed by HFS / RBS analysis (hydrogen forward scattering analysis / Rutherford backscattering analysis).

  The sheet resistance of the formed thin film was measured by a 4-terminal measurement method.

  The stress aging of the sample is measured by measuring the difference between the flatness immediately after the film formation and the flatness after being left in the sealed space for one month (flatness change amount, measurement area 142 mm × 142 mm), evaluated. The flatness was measured using a flatness measuring device UltraFLAT 200M (Corning TROPEL) on the sample surface. In addition, when the flatness change amount of the glass substrate with a conductive film is 50 nm or less, it can be said that it can be suitably used for manufacturing the reflective mask blank 1 and the reflective mask 2.

  The abrasion resistance of the thin film of the sample was evaluated by measuring the increased number of defects on the surface of the conductive film 18 after repeating the electrostatic chuck three times (M1350 manufactured by Lasertec, measuring area 132 mm × 132 mm).

  The chemical resistance of the sample was evaluated by measuring the change in film thickness after acid / alkali cleaning. The conditions for the acid washing were sulfuric acid / hydrogen peroxide with a mixing ratio of 4: 1 of sulfuric acid (98% by mass) and hydrogen peroxide (30% by mass) at a temperature of 90 ° C. for 10 minutes. The conditions for alkaline cleaning were ammonia perwater with a mixing ratio of 1: 1: 5 of ammonia (29% by mass), hydrogen peroxide (30% by mass), and water. 10 minutes. The film thickness change of the thin film of the sample was measured using a spectral film thickness meter for the film thickness of the conductive film 18 before and after cleaning.

[Preparation of Sample 1]
As Sample 1, a glass substrate with a conductive film having a TaBN conductive film 18 was produced.

The substrate 11 used for the sample 1 is a SiO ₂ —TiO ₂ glass substrate 11 (6 inch square [152.4 mm × 152.4 mm], thickness is 6.3 mm). By mechanically polishing the glass substrate 11, a smooth surface having a surface roughness Rms (root mean square roughness) of 0.15 nm (measurement region: 1 μm × 1 μm, measured with an atomic force microscope), 0.05 μm A glass substrate 11 having the following flatness was obtained.

Next, the glass substrate 11 of the sample 1 was set in a heating furnace, and the gas in the furnace was changed to the same gas as the outside of the furnace (air in the clean room), and heat treatment was performed at a heating temperature of 550 ° C. for 45 minutes. Further, the glass substrate 11 after the heat treatment is rinsed with a detergent and rinsed with pure water, and further irradiated with a Xe excimer lamp in the atmosphere, mainly by ultraviolet rays and O ₃ generated by the ultraviolet rays. The surface 71 was cleaned.

Next, a TaBN film containing Ta, B, and N was formed as a conductive film 18 on the glass substrate 11 of the sample 1 by a DC magnetron sputtering method. For film formation by the DC magnetron sputtering method, a target containing Ta and B is used, and a mixed gas of argon (Ar) gas and nitrogen (N ₂ ) gas (Ar: N ₂ = 90: 10) is used as a sputtering gas. It was. As for the composition ratio of the conductive film 18 of Sample 1, Ta was 80 atomic%, B was 10 atomic%, N was 10 atomic%, and the film thickness was 40 nm.

  Next, stress time-dependent change (flatness change), chemical resistance, and wear resistance evaluation of the glass substrate with the conductive film of Sample 1 were performed. The sheet resistance of the conductive film 18 of Sample 1 was 100Ω / □ or less, the flatness change amount was 45 nm, the film thickness change amount was less than 1 nm, and the number of defects increased was 17. From the evaluation results of the flatness change amount, chemical resistance, and wear resistance of the sample 1, the glass substrate with the conductive film of the sample 1 can be suitably used for manufacturing the reflective mask blank 1 and the reflective mask 2. It can be said.

  In addition, a glass substrate with a conductive film manufactured in the same manner as Sample 1 was placed in a heating furnace, the gas in the furnace was replaced with nitrogen, and heat treatment was performed at a heating temperature of 300 ° C. for 1 hour. An acceleration test was conducted in which hydrogen was forcibly incorporated into the conductive film. The hydrogen concentration in the conductive film 18 after the acceleration test was measured using an HFS analysis method (hydrogen forward scattering analysis method). The hydrogen content in the conductive film 18 after the acceleration test of the glass substrate with the conductive film was below the detection lower limit.

[Preparation of Sample 2]
As Sample 2, a glass substrate with a conductive film having a TaN conductive film 18 was produced. As the substrate 11 used for the sample 2, the same glass substrate 11 as that used for the sample 1 was used.

  Next, the glass substrate 11 of the sample 2 was placed in a heating furnace, and heat treatment was performed under the same conditions as the sample 1. Furthermore, the glass substrate 11 after the heat treatment was washed under the same conditions as in the sample 1.

Next, a TaN film containing Ta and N was formed as a conductive film 18 on the glass substrate 11 of the sample 2 by a DC magnetron sputtering method. For film formation by the DC magnetron sputtering method, a Ta target was used, and a mixed gas (Ar: N ₂ = 90: 10) of argon (Ar) gas and nitrogen (N ₂ ) gas was used as a sputtering gas. The TaN conductive film 18 of Sample 2 contained 80 atomic% Ta and 20 atomic% N, and the film thickness was 45 nm.

  Next, stress time-dependent change (flatness change), chemical resistance, and wear resistance evaluation of the glass substrate with the conductive film of Sample 2 were performed. The sheet resistance of the conductive film 18 of Sample 2 was 100Ω / □ or less, the flatness change amount was 40 nm, the film thickness change amount was less than 1 nm, and the number of defects increased was 12. From the evaluation results of the flatness change amount, chemical resistance, and abrasion resistance of the sample 2, the glass substrate with the conductive film of the sample 2 can be suitably used for manufacturing the reflective mask blank 1 and the reflective mask 2. It can be said.

  In addition, a glass substrate with a conductive film produced in the same manner as Sample 2 was placed in a heating furnace, the gas in the furnace was replaced with nitrogen, and heat treatment was performed at a heating temperature of 300 ° C. for 1 hour. An acceleration test was conducted in which hydrogen was forcibly incorporated into the conductive film. The hydrogen concentration in the conductive film 18 after the acceleration test was measured using an HFS analysis method (hydrogen forward scattering analysis method). The hydrogen content in the conductive film 18 after the acceleration test of the glass substrate with the conductive film was below the detection lower limit.

[Preparation of Sample 3]
As Sample 3, a glass substrate with a conductive film having a TaBN conductive film 18 was produced. As the substrate 11 used for the sample 3, the same glass substrate 11 as that used for the sample 1 was used.

Next, the glass substrate 11 of the sample 3 was set on the mounting table 44 of the light heating device 40 illustrated in FIG. 6, and the glass substrate 11 was subjected to light irradiation treatment. The periphery of the glass substrate 11 in the processing chamber 41 was set to a vacuum level of 20 Pa, and the halogen heater 46 used had a color temperature of 2500K. The light irradiation treatment was performed under the condition that the temperature of the glass substrate 11 was heated to 550 ° C. for 45 minutes. Further, the glass substrate 11 after the heat treatment is rinsed with a detergent and rinsed with pure water, and further irradiated with a Xe excimer lamp in the atmosphere, mainly by ultraviolet rays and O ₃ generated by the ultraviolet rays. The surface 71 was cleaned.

Next, a TaBN film containing Ta, B, and N was formed as the conductive film 18 on the glass substrate 11 of the sample 3 by a DC magnetron sputtering method. For film formation by the DC magnetron sputtering method, a target containing Ta and B is used, and a mixed gas of argon (Ar) gas and nitrogen (N ₂ ) gas (Ar: N ₂ = 90: 10) is used as a sputtering gas. It was. The TaBN conductive film 18 of Sample 3 contained 80 atomic% Ta, 10 atomic% B, 10 atomic% N, and a film thickness of 30 nm.

  Next, stress time-dependent change (flatness change), chemical resistance, and wear resistance evaluation of the glass substrate with the conductive film of Sample 3 were performed. The sheet resistance of the conductive film 18 of Sample 3 was 100Ω / □ or less, the flatness change amount was 40 nm, the film thickness change amount was less than 1 nm, and the number of defects increased was 18. From the evaluation results of the flatness change amount, chemical resistance, and wear resistance of the sample 3, the glass substrate with the conductive film of the sample 3 can be suitably used for manufacturing the reflective mask blank 1 and the reflective mask 2. It can be said.

  In addition, a glass substrate with a conductive film manufactured in the same manner as Sample 3 was placed in a heating furnace, the gas in the furnace was replaced with nitrogen, and heat treatment was performed at a heating temperature of 300 ° C. for 1 hour. An acceleration test was conducted in which hydrogen was forcibly incorporated into the conductive film. The hydrogen concentration in the conductive film 18 after the acceleration test was measured using an HFS analysis method (hydrogen forward scattering analysis method). The hydrogen content in the conductive film 18 after the acceleration test of the glass substrate with the conductive film was below the detection lower limit.

[Preparation of Sample 4]
As Sample 4, a glass substrate with a conductive film having a TaN conductive film 18 was produced. As the substrate 11 used for the sample 4, the same glass substrate 11 as that used for the sample 1 was used.

  Next, the glass substrate 11 of the sample 4 was set on the mounting table 44 of the light heating device 40 illustrated in FIG. 6, and light irradiation treatment was performed under the same conditions as the sample 3. Furthermore, the glass substrate 11 after the light irradiation treatment was cleaned under the same conditions as in the sample 1.

Next, a TaN film containing Ta and N was formed as a conductive film 18 on the glass substrate 11 of the sample 2 by a DC magnetron sputtering method. For film formation by the DC magnetron sputtering method, a Ta target was used, and a mixed gas (Ar: N ₂ = 90: 10) of argon (Ar) gas and nitrogen (N ₂ ) gas was used as a sputtering gas. The TaN conductive film 18 of Sample 4 contained 80 atomic% Ta and 20 atomic% N, and the film thickness was 30 nm.

  Next, stress time-dependent change (flatness change), chemical resistance, and wear resistance evaluation of the glass substrate with the conductive film of Sample 4 were performed. The sheet resistance of the conductive film 18 of Sample 4 was 100Ω / □ or less, the flatness change amount was 38 nm, the film thickness change amount was less than 1 nm, and the number of defects increased was 15. From the evaluation results of the flatness change amount, chemical resistance, and wear resistance of the sample 4, the glass substrate with the conductive film of the sample 4 can be suitably used for manufacturing the reflective mask blank 1 and the reflective mask 2. It can be said.

  In addition, a glass substrate with a conductive film produced in the same manner as Sample 4 was placed in a heating furnace, the gas in the furnace was replaced with nitrogen, and heat treatment was performed at a heating temperature of 300 ° C. for 1 hour. An acceleration test was conducted in which hydrogen was forcibly incorporated into the conductive film. The hydrogen concentration in the conductive film 18 after the acceleration test was measured using an HFS analysis method (hydrogen forward scattering analysis method). The hydrogen content in the conductive film 18 after the acceleration test of the glass substrate with the conductive film was below the detection lower limit.

[Preparation of Comparative Sample 1]
As Comparative Sample 1, a glass substrate with a conductive film having a TaBN conductive film 18 was produced. As the substrate 11 used for the comparative sample 1, the same glass substrate 11 as that used for the sample 1 was used.

  Neither heat treatment nor light irradiation treatment was performed on the glass substrate 11 of the comparative sample 1. However, the glass substrate 11 of the comparative sample 1 was cleaned under the same conditions as the sample 1.

In Comparative Sample 1, a TaBN film containing Ta, B, and N was formed as a conductive film 18 on a glass substrate 11 by a DC magnetron sputtering method. For film formation by the DC magnetron sputtering method, a target containing Ta and B is used, and a mixed gas of argon (Ar) gas and nitrogen (N ₂ ) gas (Ar: N ₂ = 90: 10) is used as a sputtering gas. It was. The TaBN conductive film 18 of Comparative Sample 1 contained 80 atomic% Ta, 10 atomic% B, and 10 atomic% N, and the film thickness was 40 nm.

  Next, stress time-dependent change (flatness change), chemical resistance, and wear resistance evaluation of the glass substrate with a conductive film of Comparative Sample 1 were performed. The sheet resistance of the conductive film 18 of Comparative Sample 1 was 100Ω / □ or less, the flatness change amount was 250 nm, the film thickness change amount was less than 1 nm, and the number of defects increased was 18. The flatness change amount of the comparative sample 1 was an excessively large value of 250 nm, and the stress change with time was confirmed. Therefore, it can be said that the glass substrate with a conductive film of Comparative Sample 1 cannot be used for manufacturing the reflective mask 2.

  In addition, a glass substrate with a conductive film produced in the same manner as Comparative Sample 1 was placed in a heating furnace, the gas in the furnace was replaced with nitrogen, and a heat treatment was performed at a heating temperature of 300 ° C. for 1 hour. An acceleration test was conducted to forcibly incorporate hydrogen into the conductive film. The hydrogen concentration in the conductive film 18 after the acceleration test was measured using an HFS analysis method (hydrogen forward scattering analysis method). It turned out that the hydrogen content in the electrically conductive film 18 after an acceleration test of this glass substrate with an electrically conductive film is about 6 atomic%.

[Preparation of Comparative Sample 2]
As Comparative Sample 2, a glass substrate with a conductive film having a TaN conductive film 18 was produced. As the substrate 11 used for the comparative sample 2, the same glass substrate 11 as that used for the sample 1 was used.

  Neither heat treatment nor light irradiation treatment was performed on the glass substrate 11 of the comparative sample 2. However, the glass substrate 11 of the comparative sample 2 was cleaned under the same conditions as the sample 1.

Next, a TaN film containing Ta and N was formed as a conductive film 18 on the glass substrate 11 of the comparative sample 2 by a DC magnetron sputtering method. For film formation by the DC magnetron sputtering method, a Ta target was used, and a mixed gas (Ar: N ₂ = 90: 10) of argon (Ar) gas and nitrogen (N ₂ ) gas was used as a sputtering gas. The TaN conductive film 18 of Comparative Sample 2 contained 80 atomic% Ta and 20 atomic% N, and the film thickness was 45 nm.

  Next, stress time-dependent change (flatness change), chemical resistance, and wear resistance evaluation of the glass substrate with a conductive film of Comparative Sample 1 were performed. The sheet resistance of the conductive film 18 of Comparative Sample 2 was 100Ω / □ or less, the flatness change amount was 265 nm, the film thickness change amount was less than 1 nm, and the number of defects increased was 14. The flatness change amount of the comparative sample 1 was an excessively large value of 265 nm, and the stress change with time was confirmed. Therefore, it can be said that the glass substrate with a conductive film of Comparative Sample 1 cannot be used for manufacturing the reflective mask 2.

  In addition, a glass substrate with a conductive film produced in the same manner as in Comparative Sample 2 was placed in a heating furnace, the gas in the furnace was replaced with nitrogen, and a heat treatment was performed at a heating temperature of 300 ° C. for 1 hour. An acceleration test was conducted to forcibly incorporate hydrogen into the conductive film. The hydrogen concentration in the conductive film 18 after the acceleration test was measured using an HFS analysis method (hydrogen forward scattering analysis method). It turned out that the hydrogen content in the electrically conductive film 18 after an acceleration test of this glass substrate with an electrically conductive film is about 6 atomic%.

[Preparation of Comparative Sample 3]
As Comparative Sample 3, a glass substrate with a conductive film having a CrON conductive film 18 was produced. As the substrate 11 used for the comparative sample 3, the same glass substrate 11 as that used for the sample 1 was used.

In Comparative Sample 3, a CrON film containing Cr, O, and N was formed as the conductive film 18 on the glass substrate 11 by a DC magnetron sputtering method. For film formation by the DC magnetron sputtering method, a Cr target is used, and a mixed gas of argon (Ar) gas, oxygen (O ₂ ) gas, and nitrogen (N ₂ ) gas (Ar: O ₂ : N ₂ =) as a sputtering gas. 70: 1: 29). The CrON conductive film 18 contained 58 atomic% of Cr, 3 atomic% of O, 39 atomic% of N, and the film thickness was 65 nm.

  Next, stress time-dependent change (flatness change), chemical resistance, and wear resistance evaluation of the glass substrate with a conductive film of Comparative Sample 3 were performed. The sheet resistance of the conductive film 18 of Comparative Sample 3 was 100Ω / □ or less, the flatness change amount was 55 nm, the film thickness change amount was 5 nm, and the number of defects increased was 120. The flatness change amount of the comparative sample 3 was a large value of 55 nm, and the stress change with time was confirmed. Further, the number of increased defects (wear resistance) was a very large value of 120. The film thickness change amount was also a large value of 5 nm. Therefore, it can be said that the glass substrate with a conductive film of Comparative Sample 1 cannot be used for manufacturing the reflective mask 2.

  In addition, a glass substrate with a conductive film produced in the same manner as Comparative Sample 3 was placed in a heating furnace, the gas in the furnace was replaced with nitrogen, and a heat treatment was performed at a heating temperature of 300 ° C. for 1 hour. An acceleration test was conducted to forcibly incorporate hydrogen into the conductive film. The hydrogen concentration in the conductive film 18 after the acceleration test was measured using an HFS analysis method (hydrogen forward scattering analysis method). It turned out that the hydrogen content in the electrically conductive film 18 after an acceleration test of this glass substrate with an electrically conductive film is about 2 atomic%.

(Examples 1-4 and Comparative Example 1)
Next, at least a Mo film / Si film periodic multilayer reflective film 12 is formed on the surface of the glass substrate with a conductive film of Samples 1 to 4 and Comparative Sample 1 on the side opposite to the surface on which the conductive film 18 is formed. By doing this, the glass substrate 11 with the multilayer reflective film 12 of Examples 1-4 and the comparative example 1 was produced.

  Specifically, a Si film (4.2 nm) is formed by ion beam sputtering on the surface opposite to the surface on which the conductive film 18 of the glass substrate with the conductive film of Samples 1 to 4 and Comparative Sample 1 is formed. The Mo film / Si film periodic multilayer reflective film 12 (total film thickness 280 nm) was formed by laminating 40 periods, with the Mo film (2.8 nm) as one period. Further, a protective film 13 (2.5 nm) made of Ru is formed on the Mo film / Si film periodic multilayer reflective film 12, and the glass substrate 11 with the multilayer reflective film of Examples 1 to 4 and Comparative Example 1 is formed. Got. When the reflectance of this protective film 13 was measured with 13.5 nm EUV light at an incident angle of 6.0 degrees, the reflectance was 63.5%.

  Furthermore, by irradiating FIB to predetermined positions of the protective film 13 and the multilayer reflective film 12 of the glass substrate 11 with the multilayer reflective film 12 of Examples 1 to 4 and Comparative Example 1, it becomes a reference for the position information of blanks defects. A reference mark was given.

  Stress change with time (flatness change) was evaluated in the same manner as Samples 1 to 4 and Comparative Samples 1 to 3 described above. As a result, in the glass substrate 11 with the multilayer reflective film 12 of Examples 1 to 4 using the glass substrate with the conductive film of Samples 1 to 4, the flatness change amount could be suppressed to 50 nm or less. However, in the glass substrate 11 with the multilayer reflective film 12 of Comparative Example 1 produced using the glass substrate with the conductive film of Comparative Sample 1, the flatness change amount exceeded 250 nm, and the stress change with time was confirmed. Therefore, it can be said that the glass substrate 11 with the multilayer reflective film 12 of Comparative Example 1 cannot be used for manufacturing the reflective mask blank 1 and the reflective mask 2.

  Moreover, it measured about the positional accuracy of the defect coordinate on the basis of the reference mark of Examples 1-4 and the comparative example 1. FIG. The positional accuracy of Examples 1 to 4 showed high accuracy to withstand use. On the other hand, the positional accuracy of Comparative Example 1 in which the change with time of stress was confirmed is low. From this point, the glass substrate 11 with the multilayer reflective film 12 of Comparative Example 1 is the reflective mask blank 1 and the reflective mask 2. It can be said that it cannot be used for the manufacture of

(Preparation of reflective mask blank 1 for EUV lithography of Examples 1 to 4)
By forming an absorber film 16 on the protective film 13 made of Ru of the glass substrate 11 with the multilayer reflective film 12 of Examples 1 to 4 manufactured as described above, the EUV lithography of Examples 1 to 4 is performed. A reflective mask blank 1 was prepared.

The absorber film 16 was formed as follows. First, a TaBN film containing Ta, B, and N was formed on the protective film 13 made of Ru as an exposure light absorber layer 14 under the absorber film 16 by a DC magnetron sputtering method. That is, using a target containing Ta and B, a film is formed by a DC magnetron sputtering method using a mixed gas (Ar: N ₂ = 90: 10) of argon (Ar) gas and nitrogen (N ₂ ) gas. did. As for the composition ratio of the formed TaBN film, Ta was 80 atomic%, B was 10 atomic%, N was 10 atomic%, and the film thickness was 56 nm.

A TaBNO film containing Ta, B, N, and O was further formed as a low reflection layer 15 on the exposure light absorber layer 14 by DC magnetron sputtering. That is, using a target containing Ta and B, a mixed gas of argon (Ar) gas, nitrogen (N ₂ ) gas, and oxygen (O ₂ ) gas (Ar: N ₂ : O ₂ = 60: 15: 25) Was used to form a film by a DC magnetron sputtering method. As for the composition ratio of the formed TaBNO film, Ta was 40 atomic%, B was 10 atomic%, N was 10 atomic%, O was 40 atomic%, and the film thickness was 14 nm. Thus, the reflective mask blank 1 for EUV lithography which has the absorber film | membrane 16 which consists of the exposure light absorber layer 14 and the low reflection layer 15 was obtained.

(Production of Reflective Mask 2 for EUV Lithography in Examples 1 to 4)
Next, using the reflective mask blank 1 for EUV lithography of Examples 1 to 4 manufactured as described above, the design rule is for EUV exposure of Examples 1 to 4 having a pattern for a DRAM having a 22 nm half pitch. The reflective mask 2 was produced as follows.

  First, an electron beam drawing resist film (120 nm) was formed on the reflective mask blank 1, and a predetermined resist pattern was formed by electron beam drawing and development.

Next, using this resist pattern as a mask, the laminated absorber film 16 is dry-etched using an ICP (Inductively Coupled Plasma) type dry etching apparatus, and the absorber film 16 becomes a transfer pattern on the absorber film 16. 22 was formed. At this time, a mixed gas of CHF ₃ gas and Ar gas is used as an etching gas, and the flow rate ratio of the CHF ₃ gas and Ar gas, the gas pressure at the time of dry etching, ICP power, and bias are appropriately adjusted, and the absorber film 16 Was dry etched.

Next, the chlorine (Cl _2), and mixed gas of oxygen _{(O 2)} (mixing ratio of chlorine (Cl ₂₎ and oxygen _{(O 2)} (flow rate ratio) is 8: 2) using a reflective area on the (absorption The Ru protective film 13 of the portion without the body film pattern) was removed by dry etching according to the absorber film pattern to expose the multilayer reflective film 12, and the reflective masks 2 of Examples 1 to 4 were obtained.

  When the final confirmation inspection of the obtained reflective masks 2 of Examples 1 to 4 was performed using the mask inspection machine, a pattern for a DRAM having a design rule of 22 nm half pitch could be formed as designed. Was confirmed. Further, the reflectance of EUV light in the reflective region was 63.5%, which was the same as the reflectance measured with the multilayer reflective film-coated substrate.

(Exposure transfer using the reflective mask 2 of Examples 1 to 4)
Next, using the obtained reflective masks 2 of Examples 1 to 4, exposure transfer was performed by a pattern transfer apparatus 50 using EUV light onto a semiconductor substrate as shown in FIG.

  The pattern transfer apparatus 50 on which the reflective mask 2 is mounted is generally composed of a laser plasma X-ray source 32, a reduction optical system 33, and the like. The reduction optical system 33 uses an X-ray reflection mirror. By the reduction optical system 33, the pattern reflected by the reflective mask 2 is usually reduced to about ¼. Since the wavelength band of 13 to 14 nm is used as the exposure wavelength, it was set in advance so that the optical path was in vacuum.

  In this state, EUV light obtained from the laser plasma X-ray source 32 is incident on the reflective mask 2, and the light reflected here passes through the reduction optical system 33 and is a silicon wafer (semiconductor substrate with a resist film) 34. Transcribed above.

  When the pattern transfer onto the semiconductor substrate was performed as described above, the accuracy of the reflective mask 2 of Examples 1 to 4 sufficiently satisfied the required accuracy of the 22 nm design rule.

1 reflective mask blank 2 reflective mask 11 substrate (glass substrate)
DESCRIPTION OF SYMBOLS 12 Multilayer reflecting film 13 Buffer film 14 Exposure light absorber layer 15 Low reflection layer 16 Absorber film 18 Conductive film 19 Resist film for electron beam drawing 21 Resist pattern 22 Absorber film pattern 31 EUV light 32 Laser plasma X-ray source 33 Reduction Optical system 34 Silicon wafer (semiconductor substrate with resist film)
DESCRIPTION OF SYMBOLS 40 Light heating apparatus 41 Processing chamber 42 Light source unit 44 Mounting stand 45 Unit frame 46 Halogen heater 47,48 Reflector 50 Pattern transfer apparatus 71 Main surface 72 Side surface 73 Chamfering surface

Claims (7)

A substrate with a multilayer reflective film for EUV lithography in which a multilayer reflective film for reflecting EUV light is formed on a glass substrate, and a conductive film is formed on the surface opposite to the surface on which the multilayer reflective film is provided. A manufacturing method of
At least the main surface of the glass substrate on the side where the conductive film is formed is mirror-polished,
At least thermal energy or light energy is applied to the mirror-polished glass substrate, the mirror-polished glass substrate is heated to 500 ° C. or more, and hydrogen contained in the mirror-polished glass substrate is desorbed. A method for producing a substrate with a multilayer reflective film for EUV lithography, comprising forming a conductive film made of a material containing tantalum and substantially not containing hydrogen.   2. The method of manufacturing a substrate with a multilayer reflective film for EUV lithography according to claim 1, wherein the application of the light energy is a light irradiation treatment using light having a wavelength of 1.3 [mu] m or more. 3. The method for manufacturing a substrate with a reflective film for EUV lithography according to claim 2, wherein the light irradiation treatment is a treatment of irradiating the mirror-polished glass substrate with light emitted from a halogen heater. The reflective film for EUV lithography according to any one of claims 1 to 3 , wherein a mark serving as a reference for positional information of defects of the mask blank is provided on a side on which the multilayer reflective film is formed. A method for manufacturing a substrate. In claim 1 of the EUV lithography multilayer reflective film coated substrate obtained by the production method according to any one of 4 the multilayer reflective film, and forming an absorber film, reflective for EUV lithography Mold mask blank manufacturing method. The EUV lithography is characterized by patterning the absorber film in the reflective mask blank for EUV lithography manufactured by the manufacturing method according to claim 5 to form an absorber film pattern on the multilayer reflective film. Method for manufacturing a reflective mask. A method of manufacturing a semiconductor device, wherein a transfer pattern is exposed and transferred onto a resist film on a semiconductor substrate using the reflective mask obtained by the method of manufacturing a reflective mask according to claim 6 .

Images