JP5559948B2 - Manufacturing method of substrate with multilayer reflective film and manufacturing method of reflective mask blank - Google Patents

Description

  The present invention relates to a substrate with a multilayer reflective film used for manufacturing a semiconductor device by a reflective lithography method, a reflective mask blank which is an original for manufacturing a reflective mask for exposure, and a method for manufacturing the same.

  With the recent increase in density and accuracy of VLSI devices, the demand for flatness and surface defects of mask blank substrates is becoming stricter year by year. As a precision polishing method for reducing the surface roughness of a conventional mask blank substrate, for example, there is a method described in Japanese Patent Application Laid-Open No. 64-40267. The surface is polished with an abrasive mainly composed of cerium oxide, and then finish-polished with colloidal silica.

Then, a cleaning process is performed on the polished substrate to remove foreign substances such as an abrasive remaining on the substrate surface. As a conventional substrate cleaning method, for example, a method disclosed in Patent Document 1 below is common. That is, the substrate is treated with a low concentration hydrofluoric acid aqueous solution, further washed with an alkaline solution, and finally washed with water (rinse).
Thus, the mask blank substrate is manufactured, and a mask blank is obtained by forming a light shielding film or a phase shift film on the upper surface of the obtained glass substrate.

  By the way, in recent years, with the demand for further miniaturization of semiconductor devices, EUV lithography, which is an exposure technique using extreme ultraviolet (Extreme Ultra Violet: hereinafter referred to as EUV) light, is one of reflective lithography. Promising. Here, EUV light refers to light in the wavelength band of the soft X-ray region or the vacuum ultraviolet region, and specifically refers to light having a wavelength of about 0.2 to 100 nm. As a mask used in this EUV lithography, for example, an exposure reflective mask described in Patent Document 2 below has been proposed.

  In such a reflective mask, 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 a reflective mask mounted on an exposure machine (pattern transfer device) is absorbed in a part where the absorber film is present, and a light image reflected by the multilayer reflective film is reflected in a part where there is no absorber film. And transferred onto the semiconductor substrate.

In the case of such an EUV reflective mask blank, the demand for the surface defect is extremely severe. In other words, when a reflective mask blank or a reflective mask is produced using a glass substrate having a convex defect due to adhesion of foreign matter or the like on the substrate surface, if there is a convex defect near the mask surface pattern, The reflected light undergoes a phase change due to the convex defect. This change in phase causes the positional accuracy and contrast of the transferred pattern to deteriorate. In particular, when short-wavelength light such as EUV light is used as exposure light, the phase change becomes very sensitive to fine irregularities on the mask surface, so that the effect on the transferred image is increased, resulting in fine irregularities. The phase change originating from the problem cannot be ignored. In the case of an EUV reflective mask blank, since the multilayer reflective film on the substrate is, for example, a film in which Mo and Si having a thickness of several nanometers are alternately laminated for about 40 to 60 cycles, is used. However, even if there are minute convex defects that do not cause any particular problems, when the multilayer reflective film is formed, the size of the defects on the substrate surface is enlarged and phase defects can occur on the surface of the multilayer reflective film. Convex defects of such a size may occur.
For this reason, particularly in the case of an EUV reflective mask blank, it is necessary to satisfy a very high level of conditions for surface defects.

Japanese Patent No. 3879828 JP 2002-122981 A

  As described above, the mask blank substrate is manufactured by subjecting it to surface polishing using an abrasive and then subjecting it to a cleaning treatment. After the cleaning process, the mask blank substrate is inspected by a defect inspection apparatus for the presence or absence of convex defects or concave defects, the size, and the position of the defects. For each inspected mask blank substrate, depending on the detected defect distribution state, it is sent as a pass product to a subsequent process (pattern forming thin film forming process) or as a reject product, a pre-process (polishing process, etc.) ) Is determined. Then, a multilayer reflective film is formed on the mask blank substrate thus manufactured to produce a multilayer reflective film-coated substrate, and further a protective film and an absorber film are formed on the multilayer reflective film for reflection. A mold mask blank is manufactured. In addition, the mask blank substrate after the multilayer reflective film is formed is also inspected for the presence or absence of convex defects or concave defects, the size thereof, and the position of the defects by a defect inspection apparatus. Each inspected glass substrate for mask blank is sent to the subsequent process (protective film or absorber film formation process, resist coating process, etc.) as an acceptable product or rejected product, depending on the distribution of detected defects. It is determined whether or not to send to the previous process (multilayer reflective film peeling process, polishing process, etc.). The defect inspection is similarly performed at the stage where the protective film is formed, the stage where the absorber film is formed, and the like.

  In recent years, the miniaturization of the transfer pattern has progressed, and accordingly, the detection accuracy of the defect inspection apparatus has also improved. As a result, the lower limit size of the detectable defect has been reduced, and it has become possible to detect a defect of a minute size that has been impossible to detect. However, in defect inspection at a detection level of a defect inspection apparatus whose defect detection lower limit size is equivalent to 150 nm, a mask blank substrate that can be sent to a subsequent process as an acceptable product (150 nm) When defect inspection is performed with a defect inspection apparatus capable of detecting less than a considerable size (e.g., equivalent to 100 nm), a large number of defects (mainly convex defects) having a size less than 150 nm are detected on the main surface, resulting in rejected products. It has been found that a mask blank substrate may be generated. It has also been found that the detected defects of less than 150 nm are not foreign matters caused by the abrasive. That is, a defect of less than 150 nm cannot be fundamentally solved by a conventional cleaning process for a glass substrate after polishing.

  Therefore, an object of the present invention is to provide a high-quality multilayer reflective film-coated substrate, a reflective mask blank, and a method of manufacturing the same, in which the number of micro-convex defects is reduced so as to satisfy a high level of defect quality requirements. is there.

Conventionally, convex defects that have been a problem in multilayer reflective films, protective films, absorber films, etc. on reflective mask blanks, except for those caused by foreign substances (such as abrasives) that were originally attached to the substrate surface, Most of the problems are caused by particles that are generated by the separation of deposits such as the inner wall of the sputtering chamber and particles that are generated by abnormal discharge of the target during film formation.
Although the present inventor has finished a good defect quality level in a mask blank substrate, a reflective mask blank in which a large number of convex defects less than 150 nm are generated in a mask blank manufactured using this substrate. The convex defect was investigated carefully. As a result, it has been found that many of such convex defects contain a large amount of oxygen in the composition. Such a convex defect containing a large amount of oxygen exists in the vicinity of the interface with the substrate in the multilayer reflective film (or grows from the vicinity of the interface). It was also found to be a micro defect (including those). Also, many of the concave defects having a size less than 150 nm also contain oxygen in the composition, and when oxygen is contained in the composition of the multilayer reflective film, the protective film, or the absorber film, the surroundings in the film (In the present specification, the defects such as convex defects and concave defects containing a large amount of oxygen are referred to as “high oxide defects”.) . Furthermore, when the actual size of the convex and concave high oxide defects with a size less than 150 nm detected by the defect inspection apparatus was examined by observation with an SEM or the like, both of them were as small as less than 150 nm. It also turned out to be. Such minute high oxide defects are confirmed for the first time by a defect inspection apparatus developed to confirm the demand for high-level surface defect freeness (the absence of defects), which has been demanded in recent years. Was able to. In recent years, with the progress of micropatterning of reflective masks, the inspection accuracy of defect inspection apparatuses has been improved, and convex defects and concave defects having a smaller size than conventional ones are not allowed.

  The present inventor found that many of the convex defects and concave defects found in the reflective mask blank are the high oxide defects, and the high oxide defects contain a large amount of oxygen. Foreign matter defects due to, for example, residual abrasives attached to the substrate surface (in this case, foreign matter defects have a higher content of Si and other elements derived from the abrasive than their surroundings, but high oxide defects tend to have that tendency. No.), particles generated by the separation of deposits such as the inner wall of the sputtering chamber, and particles generated by abnormal discharge of the target (in the case of defects caused by these particles, the size is almost 150 nm or more. ), However, with the recognition that the cause of the defect is completely different from the defect caused by the incorporation of the thin film. Cause (Mechanism) As a result of intensive studies for was assumed as follows.

  In general, a substrate with a multilayer reflective film is formed by first forming a multilayer reflective film consisting of alternating layers of a high refractive index layer and a low refractive index layer on a substrate such as a glass substrate by sputtering. Manufactured. As a sputtering method used when forming a multilayer reflective film on a substrate, an ion beam sputtering method is mainly used. The multilayer reflective film is formed by this ion beam sputtering method when the sputtering chamber in which the substrate is placed is evacuated to a predetermined vacuum level and then a sputtering gas is introduced to stabilize the gas pressure in the sputtering chamber. When an ion beam is applied to the sputter target for forming the first layer of the multilayer reflective film with an ion beam gun, sputtered particles are ejected from the target and deposited on the substrate to form one layer of the multilayer reflective film. Eyes are formed. Similarly, by applying an ion beam to a sputtering target for forming the second layer of the multilayer reflective film with an ion beam gun, a second layer is formed on the first layer of the multilayer reflective film. By repeating the process, a multilayer reflective film is formed on the substrate.

  In the case of a protective film or absorber film for a substrate with a multilayer reflective film or a reflective mask blank, a sputtering method using a DC power source or an RF power source is mainly used. Here, the DC sputtering method will be described as a representative. After the sputtering chamber in which the substrate is placed is evacuated to a predetermined degree of vacuum, a sputtering gas is introduced, and when the gas pressure in the sputtering chamber is stabilized, a voltage is applied to the sputtering target, thereby forming the sputtering gas. When it collides with the target, the sputtered particles fly out from the target and deposit on the substrate to form a thin film (a protective film, an absorber film, and a multilayer reflective film).

  In any case of the ion beam sputtering method and the sputtering method using a DC power source or an RF power source, the substrate is usually placed in the atmosphere. Therefore, the chamber for introducing the substrate in the atmosphere into the sputtering apparatus is provided on the substrate. At the time of introduction, air enters once (atmospheric pressure). For this reason, the substrate in the sputtering apparatus is placed, and it is necessary to evacuate (vacuum pressure reduction) until a predetermined degree of vacuum is obtained in any chamber in which air having substantially the same pressure as atmospheric pressure exists. . The chamber to be evacuated may be a sputter chamber for performing sputter deposition, or a chamber connected to the sputter chamber via an open / close gate (gate valve). It can be a lock room. Furthermore, a multi-chamber type in which a plurality of sputter chambers and load lock chambers are connected via a gate valve around a transfer chamber (transfer chamber) in which a transfer device (transfer robot, etc.) for transferring a substrate is installed. In the case of a (cluster type) sputtering apparatus, vacuuming may be performed in the transfer chamber.

  When evacuation is performed from a state in which air exists in a chamber in which such a substrate is placed, the internal pressure in the chamber rapidly decreases. At this time, molecules having a relatively high freezing point such as moisture and carbon dioxide in the atmosphere solidify and adhere to the substrate surface (the surface of the film already formed in the previous step) as ice or dry ice. Since the adhering ice or dry ice is solidified under a low pressure, the particle size is very small (less than 150 nm) and becomes almost spherical (true spherical, elliptical spherical, etc.). Moreover, since it crystallizes in a supercooled state, it is difficult to evaporate under low pressure. For this reason, not only when the vacuum is drawn in the sputtering chamber, but also when the substrate after being evacuated in the load lock chamber or the transfer chamber is transferred to the sputtering chamber and installed in the vacuum, it adheres to the substrate surface. Remain. When sputter film formation is performed in this state, ice or dry ice adhering to the substrate is taken in by the material of the thin film (multilayer reflection film, protective film, absorber film, etc.) deposited as it is, and oxygen is absorbed from the surroundings. It is highly probable that a lot of convex defects (convex high oxide defects) have been formed.

  For this reason, the shape of the highly oxidized defect is considered to be almost spherical (true spherical, elliptical spherical, etc.). Also, among these convex defects, those in which a thin film was formed in a state where ice and dry ice could not be melted would evaporate into a cavity when the substrate was returned to atmospheric pressure again, or Alternatively, due to the high degree of oxidation, it melts in some steps of the mask process to form cavities, the cavities collapse, and the side wall contains a concave defect (concave high oxide) containing more oxygen than the surroundings. It is considered that there is a high possibility that

The present inventor completed the present invention as a result of further earnest research based on the above elucidated facts and considerations.
That is, in order to solve the above problems, the present invention has the following configuration.
(Configuration 1)
A multilayer reflective film in which a high refractive index layer made of a material containing a metal which is a high refractive index material and a low refractive index layer made of a material containing silicon which is a low refractive index material are alternately laminated on a substrate. In the substrate with a multilayer reflective film provided, the multilayer reflective film does not have a high oxide defect having a size of less than 150 nm containing oxygen more than its periphery in the film at least in a region that is exposed to exposure light. A substrate with a multilayer reflective film.

(Configuration 2)
2. The substrate with a multilayer reflective film according to Configuration 1, wherein the high oxide defect is a defect generated in the vicinity of an interface with the substrate in the multilayer reflective film.
(Configuration 3)
3. The multilayer reflective film-coated substrate according to Configuration 1 or 2, wherein the high oxide defect is a substantially spherical defect.

(Configuration 4)
4. The multilayer reflective film-coated substrate according to any one of Structures 1 to 3, wherein the metal-containing material is molybdenum or a molybdenum compound, and the silicon-containing material is silicon or a silicon compound.

(Configuration 5)
A multilayer reflective film in which a high refractive index layer and a low refractive index layer are alternately laminated on a substrate, and a protective film made of a material containing at least one of metal and silicon formed on the multilayer reflective film. In the substrate with a multilayer reflective film provided, the protective film is free of high oxide defects having a size of less than 150 nm containing oxygen more than its surroundings in the film at least in a region receiving exposure light. A substrate with a multilayer reflective film.
(Configuration 6)
A reflective mask blank comprising an absorber film on the multilayer reflective film or the protective film of the multilayer reflective film-coated substrate according to any one of Structures 1 to 5.

(Configuration 7)
A multilayer reflective film in which a high refractive index layer and a low refractive index layer are alternately laminated on a substrate; and an absorber film made of a material containing at least one of metal and silicon formed on the multilayer reflective film; In the reflective mask blank comprising: the absorber film is characterized in that the number of high oxide defects having a size of 35 nm or more and less than 150 nm containing more oxygen than its surroundings is 10 or less. Reflective mask blank.

(Configuration 8)
A low refractive index made of a material containing a high refractive index layer made of a material containing a metal that is a high refractive index material and a silicon containing material made of a low refractive index material on the substrate by carrying the substrate into the sputtering apparatus. In the method for manufacturing a multilayer reflective film-coated substrate in which layers are alternately laminated to form a multilayer reflective film, the gas in the sputtering chamber of the sputtering apparatus on which the substrate is installed is a gas not containing moisture and carbon dioxide, dry air, or these A step of substituting with the mixed gas, a step of evacuating the substituting gas from the sputtering chamber and reducing the vacuum, and a step of forming the multilayer reflective film on the substrate by sputtering in the sputtering chamber in this order. A method for producing a multilayer reflective film-coated substrate.

(Configuration 9)
A low refractive index made of a material containing a high refractive index layer made of a material containing a metal that is a high refractive index material and a silicon containing material made of a low refractive index material on the substrate by carrying the substrate into the sputtering apparatus. In the method of manufacturing a multilayer reflective film-coated substrate in which layers are alternately stacked to form a multilayer reflective film, the gas in the decompression chamber of the sputtering apparatus on which the substrate is installed is a gas not containing moisture and carbon dioxide, dry air, or these The step of replacing the mixed gas with the gas, the step of exhausting the replaced gas from the decompression chamber to reduce the vacuum, the step of taking out the substrate from the decompression chamber and transporting it in a vacuum, and installing it in the vacuum-decompressed sputtering chamber, A method of manufacturing a substrate with a multilayer reflective film, wherein the steps of forming the multilayer reflective film on the substrate by sputtering in this order are performed in this order.

(Configuration 10)
The gas that does not contain moisture and carbon dioxide is any gas of rare gas, hydrogen gas, nitrogen gas, fluorine gas, and chlorine gas, or a mixed gas of two or more gases selected from these gases. The manufacturing method of the board | substrate with a multilayer reflective film of the structure 8 or 9.

(Configuration 11)
A low refractive index made of a material containing a high refractive index layer made of a material containing a metal that is a high refractive index material and a silicon containing material made of a low refractive index material on the substrate by carrying the substrate into the sputtering apparatus. In the method of manufacturing a multilayer reflective film-coated substrate in which layers are alternately laminated to form a multilayer reflective film, a step of evacuating a vacuum in a sputtering chamber of the sputtering apparatus in which the heated substrate is installed, and reducing the vacuum pressure, A method of manufacturing a substrate with a multilayer reflective film, wherein the step of depositing the multilayer reflective film on a substrate by a sputtering method is performed in this order in a room.

(Configuration 12)
A low refractive index made of a material containing a high refractive index layer made of a material containing a metal that is a high refractive index material and a silicon containing material made of a low refractive index material on the substrate by carrying the substrate into the sputtering apparatus. In the method for manufacturing a multilayer reflective film-coated substrate in which layers are alternately laminated to form a multilayer reflective film, the step of exhausting the gas in the decompression chamber of the sputtering apparatus in which the heated substrate is installed and vacuum decompressing, the decompression Removing the substrate from the chamber, transporting the substrate in a vacuum, and placing the multilayer reflective film on the substrate by a sputtering method in this order in the sputtering chamber. A method for producing a substrate with a multilayer reflective film.

(Configuration 13)
A substrate on which a multilayer reflective film is formed is carried into a sputtering apparatus, and a single-layer or multiple-layer protective film made of a material containing at least one of metal and silicon is formed on the multilayer reflective film by sputtering. In the method for manufacturing a substrate with a multilayer reflective film, a step of replacing the gas in the sputtering chamber of the sputtering apparatus on which the substrate is installed with a gas not containing moisture and carbon dioxide, dry air, or a mixed gas thereof, replacing the sputtering chamber Performing a step of exhausting the generated gas and performing vacuum decompression, and a step of forming at least one of the protective film or the plurality of protective films on the multilayer reflective film in this order in the sputtering chamber in this order. A method for producing a multilayer reflective film-coated substrate.

(Configuration 14)
A substrate on which a multilayer reflective film is formed is carried into a sputtering apparatus, and a single-layer or multiple-layer protective film made of a material containing at least one of metal and silicon is formed on the multilayer reflective film by sputtering. In the method for manufacturing a substrate with a multilayer reflective film, a step of replacing the gas in the reduced pressure chamber of the sputtering apparatus on which the substrate is installed with a gas not containing moisture and carbon dioxide, dry air, or a mixed gas thereof, and replacing from the reduced pressure chamber Evacuating and reducing the vacuum pressure, removing the substrate from the decompression chamber, transporting the substrate in a vacuum, and placing the substrate in a vacuum-decompressed sputtering chamber; and forming the protective film on the multilayer reflective film in the sputtering chamber Alternatively, the step of forming at least one of the plurality of protective films by a sputtering method is performed in this order. Method of manufacturing a substrate with a reflective film.

(Configuration 15)
The gas that does not contain moisture and carbon dioxide is any gas of rare gas, hydrogen gas, nitrogen gas, fluorine gas, and chlorine gas, or a mixed gas of two or more gases selected from these gases. The manufacturing method of the board | substrate with a multilayer reflective film as described in the structure 13 or 14.

(Configuration 16)
A substrate on which a multilayer reflective film is formed is carried into a sputtering apparatus, and a single-layer or multiple-layer protective film made of a material containing at least one of metal and silicon is formed on the multilayer reflective film by sputtering. In the method for manufacturing a substrate with a multilayer reflective film, a step of evacuating and vacuum-depressing a gas in a sputtering chamber of the sputtering apparatus on which the heated substrate is installed, the protective film or the protective film on the multilayer reflective film in the sputtering chamber A method for producing a substrate with a multilayer reflective film, wherein the step of forming at least one of the plurality of protective films by a sputtering method is performed in this order.

(Configuration 17)
A substrate on which a multilayer reflective film is formed is carried into a sputtering apparatus, and a single-layer or multiple-layer protective film made of a material containing at least one of metal and silicon is formed on the multilayer reflective film by sputtering. In the method for manufacturing a substrate with a multilayer reflective film, a step of evacuating a vacuum in a vacuum chamber of the sputtering apparatus in which a heated substrate is installed, vacuuming the vacuum, removing the substrate from the vacuum chamber, transporting the vacuum, A step of installing in a sputtered chamber having a reduced pressure, and a step of forming at least one of the protective film or the protective film of the plurality of layers on the multilayer reflective film in this order in the sputtering chamber in this order. A method for producing a substrate with a multilayer reflective film.

(Configuration 18)
A reflection type characterized in that an absorber film is formed on a multilayer reflection film or a protective film of a substrate with a multilayer reflection film manufactured by the method for manufacturing a substrate with a multilayer reflection film according to any one of Structures 8 to 17 Mask blank manufacturing method.

(Configuration 19)
A substrate on which a multilayer reflective film is formed is carried into a sputtering apparatus, and a single-layer or multiple-layer absorber film made of a material containing at least one of metal and silicon is formed on the multilayer reflective film by sputtering. In the method of manufacturing a reflective mask blank, the step of replacing the gas in the sputtering chamber of the sputtering apparatus on which the substrate is installed with a gas not containing moisture and carbon dioxide, dry air, or a mixed gas thereof, and replacing from the sputtering chamber A step of evacuating the vacuumed gas and reducing the vacuum, and a step of forming at least one of the absorber film or the plurality of absorber films on the multilayer reflective film in the sputtering chamber in this order. A method for producing a reflective mask blank, characterized in that:

(Configuration 20)
A substrate on which a multilayer reflective film is formed is carried into a sputtering apparatus, and a single-layer or multiple-layer absorber film made of a material containing at least one of metal and silicon is formed on the multilayer reflective film by sputtering. In the method of manufacturing a reflective mask blank, the step of replacing the gas in the reduced pressure chamber of the sputtering apparatus provided with the substrate with a gas not containing moisture and carbon dioxide, dry air, or a mixed gas thereof, and replacing from the reduced pressure chamber A step of evacuating the vacuumed gas and depressurizing in vacuum; removing the substrate from the depressurization chamber; transporting the substrate in a vacuum; and installing in a sputtering chamber depressurized in vacuum; and the absorber on the multilayer reflective film in the sputtering chamber A step of forming at least one layer of the film or the plurality of absorber films by a sputtering method in this order. Method for producing a reflective mask blank according to.

(Configuration 21)
The gas that does not contain moisture and carbon dioxide is any gas of rare gas, hydrogen gas, nitrogen gas, fluorine gas, and chlorine gas, or a mixed gas of two or more gases selected from these gases. The manufacturing method of the reflective mask blank of the structure 19 or 20.

(Configuration 22)
A substrate on which a multilayer reflective film is formed is carried into a sputtering apparatus, and a single-layer or multiple-layer absorber film made of a material containing at least one of metal and silicon is formed on the multilayer reflective film by sputtering. In the manufacturing method of the reflective mask blank, the step of evacuating the vacuum in the sputtering chamber of the sputtering apparatus provided with the heated substrate and depressurizing the vacuum, the absorber film on the multilayer reflective film in the sputtering chamber Or the manufacturing method of the reflective mask blank characterized by performing the process of forming into a film at least one layer by sputtering method among the said absorber films of multiple layers in this order.

(Configuration 23)
A substrate on which a multilayer reflective film is formed is carried into a sputtering apparatus, and a single-layer or multiple-layer absorber film made of a material containing at least one of metal and silicon is formed on the multilayer reflective film by sputtering. In the reflective mask blank manufacturing method, the step of evacuating and vacuuming the gas in the vacuum chamber of the sputtering apparatus on which the heated substrate is installed, removing the substrate from the vacuum chamber and transporting it in the vacuum, A step of installing in a sputtered chamber having a reduced pressure, and a step of forming at least one layer of the absorber film or the plurality of absorber films on the multilayer reflective film by the sputtering method in this order in the sputtering chamber are performed in this order. A manufacturing method of a reflective mask blank characterized by the above.

  According to the present invention, ice or dry ice adhering to the substrate surface or the like during vacuum depressurization, which is considered to be a cause of high oxide defects, is evaporated before sputter deposition, or such ice or dry ice is generated. By suppressing itself, generation of minute high oxide defects can be reduced, so that a high-quality substrate with a multilayer reflective film, a reflective mask blank and production thereof can be satisfied so as to satisfy a high level of defect quality requirements. A method can be provided.

It is sectional drawing which shows one Embodiment of a reflection type mask blank. It is a schematic block diagram of the sputtering device which concerns on 1st Embodiment. It is a schematic block diagram of one form of the sputtering device which concerns on 2nd Embodiment. It is a schematic block diagram of another form of the sputtering device which concerns on 2nd Embodiment.

Hereinafter, the present invention will be described in detail by embodiments.
In the present invention, a high refractive index layer made of a material containing a metal which is a high refractive index material and a low refractive index layer made of a material containing silicon which is a low refractive index material are alternately laminated on a substrate. In the substrate with a multilayer reflective film provided with the multilayer reflective film, the multilayer reflective film is free from high oxide defects having a size of less than 150 nm containing oxygen more than its surroundings in the film. It is a substrate with a film. Further, the present invention is a reflective mask blank in which a protective film (if necessary) and an absorber film are formed on the multilayer reflective film of the substrate with the multilayer reflective film.

An embodiment of a substrate with a multilayer reflective film according to the present invention has a configuration in which a multilayer reflective film 2 is formed on a substrate 1 with reference to FIG. An embodiment of the reflective mask blank according to the present invention is a reflective mask blank 10 having a structure in which the layers of the protective film 3 and the absorber film 4 are formed on the multilayer reflective film 2.
Here, the substrate 1 is preferably a SiO ₂ —TiO ₂ -based low thermal expansion glass substrate as will be described later.
The multilayer reflective film 2 is a multilayer film in which materials having different refractive indexes are periodically laminated as described above, and will be described in detail later. The details of the protective film 3 and the absorber film 4 will be described later.

The substrate with a multilayer reflective film and the reflective mask blank according to the present invention are characterized in that there is no high oxide defect having a size of less than 150 nm in at least a region of the multilayer reflective film that is irradiated with exposure light. .
The defect of the multilayer reflective film, which the present invention aims to reduce in particular, is a high oxidation mainly caused by particles containing oxygen such as ice and dry ice generated at the time of evacuation after introducing the substrate into the sputtering apparatus. It is an object defect and cannot be detected by a 150 nm sensitivity defect inspection apparatus that has been widely used in the past, but can be detected by a higher sensitivity defect inspection apparatus (such as a defect inspection apparatus such as 140 nm sensitivity or 100 nm sensitivity). (Less than 150 nm, 140 nm or less, 100 nm or less, 60 nm or less, etc.).

  Particles such as ice and dry ice that are generated when evacuating are approximately spherical on average about 50 to 100 nm, but when a multilayer reflective film is formed on the substrate, the height is several nm on the substrate. Even so, if there is a convex defect, the multilayer reflective film is inclined with respect to the main surface of the substrate with the convex defect portion as the center. In a portion where the multilayer reflective film is formed at an inclination, EUV exposure light is not reflected at a normal reflection angle or the reflectance is locally lowered, which is a serious problem. For this reason, at least in a region that receives irradiation with EUV exposure light, it is necessary that no high oxide defects exist in the multilayer reflective film. The region to be irradiated with EUV exposure light refers to the center of the main surface of the substrate in the case of a general substrate of about 152 mm square size, for example, when this multilayer reflective film-coated substrate is used as a reflective mask. It is necessary to guarantee at least the area within the 132 mm square, and it is safer to guarantee the area within the 142 mm square and the area within the 148 mm square, but the entire surface of the substrate main surface is highly oxidized in the multilayer reflective film. It is optimal that there are no physical defects.

In the reflective mask blank according to the present invention, the number of high oxide defects having a size of 35 nm or more and less than 150 nm in the absorber film is 10 or less.
The defect of the absorber film, which the present invention aims to reduce in particular, is a high oxidation in which particles containing oxygen such as ice and dry ice generated at the time of evacuation after introducing the substrate into the sputtering apparatus are the core. It is an object defect and cannot be detected by a 150 nm sensitivity defect inspection apparatus that has been widely used in the past, but can be detected by a higher sensitivity defect inspection apparatus (such as a defect inspection apparatus such as 140 nm sensitivity or 100 nm sensitivity). (Less than 150 nm, 140 nm or less, 100 nm or less, 60 nm or less, etc.). In addition, it is a reflective mask used for exposure transfer by EUV exposure light, and in order to be applicable to a reflective mask blank for producing a reflective mask of DRAM hp 45 nm generation or later, at least an absorber film is used. It is necessary to guarantee the maximum number of existing high oxide defects of 35 nm or more. The maximum number of such high oxide defects that are allowed to exist in the absorber film is within the transfer pattern region (when the reflective mask is manufactured, the transfer pattern is formed on the absorber film). Is 10 or less in a region in which is formed, for example, a region within a 132 mm square with respect to the center of the reflective mask blank. If the number of high oxide defects is up to 10, it is within a range that can be dealt with by adjusting the position of the transfer pattern formed on the absorber film and correcting the defects.

  Further, in order to be applicable to a reflective mask blank for producing a reflective mask of DRAM hp32 nm generation or later, the number of existence of high oxide defects of 25 nm or more in the transfer pattern region is 10 in the absorber film. It is desirable to guarantee the following. In order to make it applicable to a reflective mask blank for producing a reflective mask of DRAM hp22 nm generation or later, the number of high oxide defects of 18 nm or more in the transfer pattern region is reduced to 10 or less in the multilayer reflective film. It is desirable to guarantee.

  In addition, in the case where higher accuracy is required for the reflective mask blank that can correspond to each of these generations, the number of high oxide defects in the absorber film is preferably 8 or less, more Preferably it is 5 or less. Further, the region that guarantees the number of high oxide defects in the absorber film may be within a 142 mm square with respect to the center of the reflective mask blank. Furthermore, in the present invention, the number of high oxide defects of less than 150 nm is guaranteed, but the guaranteed range may be expanded to, for example, 150 nm or less, 200 nm or less, and the like.

The substrate with a multilayer reflective film and the reflective mask blank according to the present invention are characterized in that high oxide defects having a size of less than 150 nm do not exist in at least a region of the protective film that is irradiated with exposure light.
The defect of the protective film, which the present invention aims to reduce in particular, is a high oxide whose core contains particles containing oxygen, such as ice and dry ice, generated during evacuation after introducing the substrate into the sputtering apparatus. A defect that cannot be detected by a 150 nm-sensitive defect inspection apparatus that has been widely used in the past, and that can be detected by a defect inspection apparatus with higher sensitivity (such as a defect inspection apparatus such as 140 nm sensitivity or 100 nm sensitivity) ( Less than 150 nm, 140 nm or less, 100 nm or less, 60 nm or less, etc.).

  There are cases where the protective film is left without removing a portion of the region that is irradiated with the exposure light during use or removed. In particular, when it is left without being removed, the film thickness is very thin (for example, 5 nm or less) in order to minimize the attenuation of EUV exposure light when passing through the protective film. When a protective film is formed in a state where particles such as ice and dry ice having an average size of about 50 to 100 nm adhere to the outermost surface of the multilayer reflective film, the protective film is substantially formed on that portion. In other words, the multilayer reflective film is exposed. For this reason, at least in the region that is irradiated with the EUV exposure light, it is necessary that no high oxide defect exists in the protective film. The region that receives the EUV exposure light is the same as in the case of the multilayer reflective film.

  The defect inspection machine having a sensitivity of 150 nm referred to here is a polystyrene latex (PSL) particle having a particle diameter of 150 nm on a substrate (PSL particles have a probability of being 1% or less when the particles are close to each other within 1 mm. This means a defect inspection apparatus that can detect the PSL particles even when a defect inspection is performed on a specimen having a variety of characteristics.

  Check whether the convex or concave defects of the multilayer reflective film, protective film, or absorber film detected by the defect inspection system are high oxide defects on the multilayer reflective film-coated substrate or reflective mask blank. As a method, as described in Examples described later, for example, a method based on cross-sectional TEM observation or EDX analysis can be used.

  The present invention relates to a production method suitable for obtaining a substrate with a multilayer reflective film and a reflective mask blank in which the number of high oxide defects in the multilayer reflective film, protective film and absorber film as described above is reduced. Also provide. Although the principle of the ion beam sputtering method and the sputtering method using a DC power source or an RF power source are largely different, the steps related to vacuum decompression when a substrate under atmospheric pressure is introduced into a sputtering apparatus are substantially the same. Therefore, in each of the following embodiments, a case where the present invention is applied to both a method for manufacturing a substrate with a multilayer reflective film and a method for manufacturing a reflective mask blank will be described.

[First Embodiment]
In the first embodiment of the method for manufacturing a substrate with a multilayer reflective film and a reflective mask blank according to the present invention, the gas in the sputtering chamber of the sputtering apparatus in which the substrate is installed is a gas containing no moisture and carbon dioxide, dry air. Alternatively, a process of substituting with the mixed gas, a process of exhausting the substituted gas from the sputtering chamber and evacuating the vacuum, and forming a multilayer reflective film (protective film or absorber film) on the substrate by sputtering in the sputtering chamber. This is characterized in that the steps are performed in this order.

FIG. 2 is a schematic configuration diagram of a sputtering apparatus to which the first embodiment is applied.
A sputtering apparatus 20 shown in FIG. 2 includes a sputtering chamber (deposition chamber) 21 and a transfer apparatus (transfer robot) 22. The sputtering apparatus 20 has a substrate 1 (a multilayer reflective film 2 formed on the atmosphere). The substrate 1 or the substrate 1) on which the multilayer reflective film 2 and the protective film 3 are formed is directly carried into the sputtering chamber 21. In the case of the sputtering apparatus 20 having such a configuration, first, the opening / closing gate (gate valve) 23 of the substrate 1 placed in the atmosphere (the air in the clean room room) is opened by the transfer apparatus 22 to open the room to the atmosphere. The sputter chamber 21 is carried in, and the open / close gate 23 is closed. Then, while exhausting the gas in the sputtering chamber 21 (which is substantially the same as the air in the clean room and containing moisture and carbon dioxide), the gas does not contain moisture and carbon dioxide, dry air, or a mixed gas thereof (substitution) The gas in the sputtering chamber 21 is replaced with a gas not containing moisture and carbon dioxide, dry air, or a mixed gas thereof. After the replacement, vacuum decompression for exhausting the gas in the sputtering chamber 21 is performed, and the inside of the sputtering chamber 21 is set to a predetermined degree of vacuum. Thereafter, a sputtering gas is introduced into the sputtering chamber 21, and when a predetermined gas pressure is reached, a multilayer reflective film 2 (protective film) is formed on the substrate 1 by a sputtering method (ion beam sputtering method, DC sputtering method, RF sputtering method, etc.). Film 3 or absorber film 4) is formed.

  If the protective film 3 (absorber film 4) is composed of a plurality of layers and can be formed with the same sputter target, the first layer is formed and the substrate 1 is left in the sputter chamber 21 as it is. Even if the sputtering gas is replaced without opening and the second and subsequent layers are formed, high oxide defects in the film can be suppressed.

  As described above, after carrying in and installing the substrate 1 (the substrate 1 on which the multilayer reflective film 2 is formed or the substrate 1 on which the multilayer reflective film 2 and the protective film 3 are formed), moisture such as air from the inside of the sputtering chamber 21. After the gas containing carbon dioxide and carbon dioxide is discharged and replaced with a gas not containing moisture and carbon dioxide, dry air, or a mixed gas thereof, vacuum decompression is performed to make the inside of the sputtering chamber 21 have a predetermined degree of vacuum. As a result, even if the internal pressure in the sputtering chamber 21 decreases during vacuum decompression, the sputtering chamber 21 is a gas that is a gas at normal temperature but has a relatively high freezing point, a gas that does not contain carbon dioxide, and hardly contains water. Since it is replaced with dry air, the generation of solidified substances such as ice and dry ice can be suppressed, and the solidified substances adhere to the surface of the substrate 1 (the surface of the multilayer reflective film 2 or the surface of the protective film 3). This can be suppressed more reliably than before. Therefore, even if the multilayer reflective film 2 and the protective film 3 are formed by sputtering after this vacuum decompression, the generation of high oxide defects caused by the solidified material can be reliably suppressed. In addition, even when the absorber film 4 is formed by a sputtering method after vacuum depressurization, generation of high oxide defects caused by the solidified substance is within an allowable range (high oxide defects having a size of 35 nm or more and less than 150 nm). 10 or less in the transfer pattern area).

The gas not containing moisture and carbon dioxide includes any gas of noble gas (helium, neon, argon, krypton, xenon, radon), hydrogen gas, nitrogen gas, fluorine gas, and chlorine gas, or from these gases. A mixed gas of two or more gases selected is preferable.
As a means for introducing the replacement gas into the sputter chamber 21, a pipe for supplying the replacement gas is used for returning the sputter gas into the sputter chamber 21 or the internal pressure in the sputter chamber 21 to atmospheric pressure. For example, a configuration in which a pipe for supplying gas to be connected is connected via a branch joint, or a configuration in which the gas is directly connected to the sputtering chamber 21 can be applied.

[Second Embodiment]
In the second embodiment of the method for manufacturing a substrate with a multilayer reflective film and a reflective mask blank according to the present invention, the gas in the decompression chamber of the sputtering apparatus on which the substrate is installed, the gas not containing moisture and carbon dioxide, dry air Or a process of substituting these mixed gases, a process of exhausting the gas substituted from the decompression chamber and reducing the vacuum, a step of removing the substrate from the decompression chamber and transporting it in a vacuum, and installing it in a vacuum-decompressed sputtering chamber, A feature is that the step of forming a multilayer reflective film (protective film or absorber film) on a substrate by sputtering is performed in this order in a room.

FIG. 3 is a schematic configuration diagram of an embodiment of a sputtering apparatus to which the second embodiment is applied.
A sputtering apparatus 30 shown in FIG. 3 includes a sputtering chamber (deposition chamber) 31 and a decompression chamber (load lock chamber) 34 connected via an open / close gate 33, and a transport device (transport robot) 32 in the decompression chamber 34. Is installed. The sputtering apparatus 30 is configured to transfer a substrate 1 (the substrate 1 on which the multilayer reflective film 2 is formed, or the substrate 1 on which the multilayer reflective film 2 and the protective film 3 are formed) in the decompression chamber 34 by the transport device 32. The sputter chamber 31 is loaded and subjected to vacuum depressurization in the decompression chamber 34 in which the substrate 1 is installed, and the sputtering chamber 31 is configured not to be open to the atmosphere during normal times except for maintenance. .

  In the case of the sputtering apparatus 30 having such a configuration, first, the open / close gate (gate valve) 35 is opened by the transfer device 32 for the substrate 1 placed in the atmosphere (air in the clean room room), and the room is opened to the atmosphere. It is carried into the decompression chamber 34 and the open / close gate 35 is closed. Then, while exhausting the gas in the decompression chamber 34 (which is substantially the same as the air in the clean room and containing moisture and carbon dioxide), the gas does not contain moisture and carbon dioxide, dry air, or a mixed gas thereof (substitution) Gas) is introduced to replace the gas in the decompression chamber 34 with a gas not containing moisture and carbon dioxide, dry air, or a mixed gas thereof. After the replacement, vacuum decompression for exhausting the gas in the decompression chamber 34 is performed, and the interior of the decompression chamber 34 is set to a predetermined degree of vacuum. Next, the open / close gate 33 that has been closed is opened, the substrate 1 is taken out from the decompression chamber 34 by the transfer device 32, and is loaded into and installed in the sputtering chamber 31 that is vacuum depressurized to a predetermined vacuum degree. Close again. Finally, a sputtering gas is introduced into the sputtering chamber 31, and when a predetermined gas pressure is reached, the multilayer reflective film 2 (on the substrate 1) is formed by sputtering (ion beam sputtering, DC sputtering, RF sputtering, etc.). A protective film 3 or an absorber film 4) is formed.

  If the protective film 3 (absorber film 4) is composed of a plurality of layers and can be formed with the same sputter target, the first layer is formed and then the substrate 1 is left in the sputter chamber 31 as it is. Even if the sputtering gas is replaced without opening and the second and subsequent layers are formed, high oxide defects in the film can be suppressed.

  As described above, after carrying in / installing the substrate 1 (the substrate 1 on which the multilayer reflective film 2 is formed or the substrate 1 on which the multilayer reflective film 2 and the protective film 3 are formed), moisture such as air from the decompression chamber 34. The gas containing carbon dioxide and carbon dioxide is discharged and replaced with a gas not containing moisture and carbon dioxide, dry air, or a mixed gas thereof, and then vacuum decompression is performed to make the decompression chamber 34 have a predetermined degree of vacuum. Thereby, even if the internal pressure in the decompression chamber 34 is reduced during vacuum decompression, the decompression chamber 34 is a gas that is a gas at room temperature but has a relatively high freezing point, does not contain carbon dioxide, or contains almost no water. Since it is replaced with dry air, the generation of solidified substances such as ice and dry ice can be suppressed, and the solidified substances adhere to the surface of the substrate 1 (the surface of the multilayer reflective film 2 or the surface of the protective film 3). This can be suppressed more reliably than before. Further, since the substrate 1 is transported and installed to the sputter chamber 31 where the vacuum is reduced to a predetermined degree of vacuum without opening to the atmosphere, the solidified substance is not removed even during the period from when the substrate 1 is installed in the sputter chamber 31. Adhesion can be suppressed. Therefore, even when the multilayer reflective film 2 and the protective film 3 are formed in the sputtering chamber 31 by the sputtering method, the generation of high oxide defects caused by solidified substances such as ice and dry ice can be reliably suppressed. Further, even when the absorber film 4 is formed by the sputtering method, generation of high oxide defects caused by the solidified substance is within an allowable range (high oxide defects having a size of 35 nm or more and less than 150 nm are transferred pattern regions. 10 or less) can be reliably suppressed.

In the method of manufacturing a mask blank according to the second embodiment in the sputtering apparatus 30, since the inside of the sputtering chamber 31 is not normally opened to the atmosphere, particles, contaminants, and the like in the clean room chamber are in the sputtering chamber 31. Intrusion can be suppressed.
Other matters regarding the replacement gas are the same as those in the first embodiment.
In the sputtering apparatus 30 as well, the substrate 1 is not vacuum-depressed when the substrate 1 is placed in the decompression chamber 34, but the substrate is placed in the sputtering chamber 31 once returned to the atmospheric pressure as in the first embodiment. Even if 1 is carried in and the inside of the sputter chamber 31 is replaced with the above-described replacement gas and then the vacuum is reduced, the generation of solidified substances such as ice and dry ice is suppressed, and the multilayer reflection film 2 generated due to the suppression. About suppression of generation | occurrence | production of the high oxide defect in (the protective film 3 or the absorber film | membrane 4), the effect equivalent to 1st Embodiment is acquired.
As means for introducing the replacement gas into the decompression chamber 34, a pipe for supplying the replacement gas is connected to a pipe for supplying a gas used when the internal pressure in the decompression chamber 34 is returned to the atmospheric pressure via a branch joint. A connection configuration, a configuration directly connected to the decompression chamber 34, or the like can be applied. The means for introducing the replacement gas into the sputtering chamber 31 is the same as in the first embodiment.

FIG. 4 is a schematic configuration diagram of another form of the sputtering apparatus to which the second embodiment is applied.
A sputtering apparatus 40 shown in FIG. 4 is a multi-chamber type (cluster type) sputtering apparatus. As its configuration, the decompression chambers (load lock chambers) 44A and 44B dedicated for substrate loading and unloading are opened and closed gates, respectively, centering on a transfer chamber (transfer chamber) 47 in which a transfer device (transfer robot) 42 is installed. (Gate valves) 46A and 46B are connected, and a plurality of sputtering chambers 41A and 41B are connected through open / close gates (gate valves) 43A and 43B, respectively. Further, the substrate 1 (the substrate 1 on which the multilayer reflective film 2 is formed or the substrate 1 on which the multilayer reflective film 2 and the protective film 3 are formed) is loaded into the decompression chamber 44A, and the substrate 1 is unloaded from the decompression chamber 44B. The transfer device (transfer robot) 48 is provided.
This sputtering apparatus 40 carries the substrate 1 in the atmosphere into the decompression chamber 44A by the transport device 48, and performs vacuum decompression in the decompression chamber 44A in which the substrate 1 is installed, and the sputtering chambers 41A, 42A, The transfer chamber 47 is configured such that the room is not normally opened to the atmosphere except in the case of maintenance.

  In the case of the sputtering apparatus 40 having such a configuration, first, the opening / closing gate (gate valve) 45A is opened by the transfer device 48 for the substrate 1 placed in the atmosphere (the air in the clean room room), and the room is opened to the atmosphere. It is carried into the reduced pressure chamber 44A and the open / close gate 45A is closed. Then, while exhausting the gas in the decompression chamber 44A (which is substantially the same as the air in the clean room room and containing moisture and carbon dioxide), a gas not containing moisture and carbon dioxide, dry air, or a mixed gas thereof is introduced. Then, the gas in the decompression chamber 44A is replaced with a gas not containing moisture and carbon dioxide, dry air, or a mixed gas thereof. After the replacement, vacuum decompression for exhausting the gas in the decompression chamber 44A is performed, and the interior of the decompression chamber 44A is set to a predetermined vacuum level.

Next, the open / close gates 43A and 46A that have been closed so far are opened, the substrate 1 is taken out from the decompression chamber 44A by the transport device 42, and the predetermined vacuum is passed through the transport chamber 47 that is vacuum-depressed to a predetermined vacuum degree. It is carried in and installed in the sputter chamber 41A, which is vacuum-reduced every time, and the open / close gates 43A and 46A are closed again. Thereafter, a sputtering gas is introduced into the sputtering chamber 41A, and when a predetermined gas pressure is reached, a multilayer reflective film 2 (protective film) is formed on the substrate 1 by a sputtering method (ion beam sputtering method, DC sputtering method, RF sputtering method, etc.). Film 3 or absorber film 4) is formed.
When the protective film 3 (absorber film 4) is composed of a plurality of layers and can be formed with the same sputter target, after the first layer is formed, the substrate 1 is left in the sputter chamber 41A as it is and is opened to the atmosphere. Without changing the sputtering gas, the second and subsequent layers are formed.

  Further, when it is necessary to form the protective film 3 without opening to the atmosphere after the multilayer reflective film 2 is formed, the protective film 3 (absorber film 4) has a plurality of layers, and the second and subsequent layers are differently sputtered. When it is necessary to form a film on the target, the film is formed on the sputtering chamber 41B. In this case, the inside of the sputtering chamber 41A is depressurized to a predetermined degree of vacuum, then the open / close gates 43A and 43B are opened, the substrate 1 is taken out from the sputtering chamber 41A by the transfer device 42, and passed through the transfer chamber 47 to a predetermined vacuum. It is carried in and installed in the sputter chamber 41B which has been evacuated and reduced, and the open / close gates 43A and 43B are closed again. Thereafter, a sputtering gas is introduced into the sputtering chamber 41B, and when a predetermined gas pressure is reached, the protective film 3 (the protective film 3 and the absorber) is formed by a sputtering method (ion beam sputtering method, DC sputtering method, RF sputtering method, etc.). The second and subsequent layers of film 4 are formed.

  When all the layers of the protective film 3 (absorber film 4) to be formed by the sputtering apparatus 40 have been formed, the open / close gate 46B of the decompression chamber 44B that has been decompressed to a predetermined degree of vacuum, and at that time Then, the open / close gate 43A (43B) of the sputter chamber 41A (41B) in which the substrate 1 is installed is opened, and the substrate 1 is taken out of the sputter chamber 41A (41B) by the transfer device 42, and is passed through the transfer chamber 47 to the decompression chamber. 44B is loaded and installed, and the open / close gates 43A (43B) and 46B are closed again. Finally, the inside of the decompression chamber 44B is opened to the atmosphere, the open / close gate 45B is opened, and the substrate 1 is taken out from the decompression chamber 44B by the transfer device 48.

  As described above, after carrying in / installing the substrate 1 (the substrate 1 on which the multilayer reflective film 2 is formed or the substrate 1 on which the multilayer reflective film 2 and the protective film 3 are formed), moisture such as air from the decompression chamber 44A. After the gas containing carbon dioxide and carbon dioxide is discharged and replaced with a gas not containing moisture and carbon dioxide, dry air, or a mixed gas thereof, vacuum decompression is performed to make the decompression chamber 44A have a predetermined degree of vacuum. Thereby, even if the internal pressure in the decompression chamber 44A is reduced during vacuum decompression, the decompression chamber 44A is a gas that is a gas at room temperature but has a relatively high freezing point, a gas that does not contain carbon dioxide, and hardly contains water. Since it is replaced with dry air, the generation of solidified substances such as ice and dry ice can be suppressed, and the solidified substances adhere to the surface of the substrate 1 (the surface of the multilayer reflective film 2 or the surface of the protective film 3). This can be suppressed more reliably than before. Further, without opening the substrate 1 to the atmosphere, the substrate 1 passes through the transfer chamber 47 that is vacuum-depressed to a predetermined degree of vacuum (transported in a vacuum), and is then sputtered chamber 41A (depressurized to a predetermined degree of vacuum) ( 41B), the adhesion of the solidified substance can be suppressed even during the period until the substrate 1 is installed in the sputtering chamber 41A (41B). Therefore, even if the multilayer reflective film 2 and the protective film 3 are formed by sputtering in the sputtering chamber 41A (41B), generation of high oxide defects caused by solidified substances such as ice and dry ice is reliably suppressed. it can. Further, even when the absorber film 4 is formed by the sputtering method, generation of high oxide defects caused by the solidified substance is within an allowable range (high oxide defects having a size of 35 nm or more and less than 150 nm are transferred pattern regions. 10 or less) can be reliably suppressed.

In the mask blank manufacturing method according to the second embodiment in the sputtering apparatus 40, the inside of the sputtering chambers 41A and 41B and the inside of the transfer chamber 47 which is the transfer path of the substrate 1 are not normally opened to the atmosphere. In addition, it is possible to prevent particles, contaminants, and the like in the clean room from entering the sputtering chambers 41A and 41B and the transfer chamber 47.
Other matters regarding the replacement gas are the same as those in the first embodiment.
In this sputtering apparatus 40, the vacuum pressure is not reduced when the substrate 1 is placed in the decompression chamber 44A, but the transport chamber 47 is also used as the decompression chamber, that is, the transport chamber 47 once returned to the atmospheric pressure. At a certain stage, the inside of the transfer chamber 47 may be replaced with the replacement gas, and then the vacuum may be reduced. In this case, regarding the suppression of the generation of solidified substances such as ice and dry ice and the suppression of the generation of high oxide defects in the multilayer reflective film 2 (protective film 3 or absorber film 4) resulting therefrom, An effect equivalent to that of the first embodiment can be obtained.

Also in this sputtering apparatus 40, the vacuum is not reduced when the substrate 1 is placed in the decompression chamber 44A, but the sputtering chamber 41A (returned to the atmospheric pressure once) as in the first embodiment. 41B), even if the inside of the sputtering chamber 41A (41B) is replaced with the above-described replacement gas and then vacuum-depressurized, the generation of solidified substances such as ice and dry ice is suppressed, and as a result, With respect to the suppression of the generation of high oxide defects in the resulting multilayer reflective film 2 (protective film 3 or absorber film 4), the same effect as in the first embodiment can be obtained.
As a means for introducing the replacement gas into the decompression chamber 44A and the transfer chamber 47, a gas used when returning the internal pressure in the decompression chamber 44A and the transfer chamber 47 to the atmospheric pressure by using a pipe for supplying the replacement gas. It is possible to apply a configuration in which the pipe is connected to the pipe for supplying the gas via a branch joint, or a configuration in which the pipe is directly connected to the decompression chamber 44 </ b> A or the transfer chamber 47. The means for introducing the replacement gas into the sputtering chambers 41A and 41B is the same as in the case of the first embodiment.

In the configuration shown in the first embodiment and the second embodiment described above, in the sputtering chamber, the decompression chamber, and the transfer chamber in which the substrate is installed and the chamber in an open air state is vacuum-depressed, However, in order to further reduce the number of high oxide defects generated in the absorber film 4 (for example, 5 or less), the water and carbon dioxide in the room to be evacuated and vacuumed are more reliably used. It is desirable to eliminate. In particular, in the case of the multilayer reflective film 2 and the protective film 3, it is necessary to more surely eliminate the water and carbon dioxide in the room to be vacuum-depressed so as not to have high oxide defects. In consideration of these points, it is desirable that the gas to be replaced is only a gas that does not contain moisture and carbon dioxide.
Further, hydrogen gas and nitrogen gas are desirable from the viewpoint of the cost of the gas used, and nitrogen gas is optimal from the viewpoint of ease of gas management.

[Third Embodiment]
A third embodiment of the method for manufacturing a multilayer reflective film-coated substrate or a reflective mask blank according to the present invention is a step of evacuating a vacuum in a sputtering chamber of a sputtering apparatus in which a heated substrate is installed, In the sputtering chamber, the step of forming the multilayer reflective film (protective film or absorber film) on the substrate by the sputtering method is performed in this order.

  Here again, using the sputtering apparatus 20 shown in FIG. 2 described above, in one aspect of the sputtering apparatus to which the third embodiment is applied, a heating apparatus for heating the substrate 1 is provided in the sputtering chamber 21. It is the structure of the sputter device. In this case, the sputtering apparatus 20 carries the substrate 1 in the atmosphere into the sputtering chamber 21 by the transfer device 22, closes the open / close gate 23, operates the heating device, and operates the multilayer reflective film 2 (protection) on the substrate 1. The outermost surface on the side on which the film 3 or the absorber film 4) is formed (when the multilayer reflective film 2 is formed, the main surface of the substrate, when the protective film 3 is formed, or without the protective film 3 being provided with the absorber) When the film 4 is formed, the surface of the multilayer reflective film 2 and when the absorber film 4 is formed on the protective film 3 are heated until the surface of the protective film 3) reaches a predetermined temperature or higher. To do. Here, the predetermined temperature is a solidified substance such as ice or dry ice in which moisture or carbon dioxide in the gas generated in the chamber from when the vacuum in the sputtering chamber 21 is reduced to a predetermined degree of vacuum. Is a temperature that evaporates when adhering to the surface of the substrate 1 (multilayer reflective film 2, protective film 3). And vacuum depressurization which exhausts the gas in the sputter | spatter chamber 21 is performed, and it is set as predetermined vacuum degree. Finally, a sputtering gas is introduced into the sputtering chamber 21, and when a predetermined gas pressure is reached, the multilayer reflective film 2 (on the substrate 1) is formed by sputtering (ion beam sputtering, DC sputtering, RF sputtering, etc.). A protective film 3 or an absorber film 4) is formed.

  As described above, when the vacuum in the sputtering chamber 21 is reduced, the surface of the substrate 1 (the multilayer reflective film 2 and the protective film 3) is set to a temperature at which a solidified material such as ice or dry ice evaporates. Therefore, after the inside of the sputtering chamber 21 reaches a predetermined degree of vacuum and the vacuum pressure reduction is finished, the adhesion of the solidified substance to the surface of the substrate 1 (multilayer reflective film 2 and protective film 3) can be suppressed more reliably than before. . Therefore, even if the multilayer reflective film 2 and the protective film 3 are formed by sputtering after this vacuum decompression, the generation of high oxide defects caused by the solidified material can be reliably suppressed. Further, even when the absorber film 4 is formed by the sputtering method, generation of high oxide defects caused by the solidified substance is within an allowable range (high oxide defects having a size of 35 nm or more and less than 150 nm are transferred pattern regions. 10 or less) can be reliably suppressed.

As a heating device for bringing the surface of the substrate 1 (the multilayer reflective film 2 and the protective film 3) to a predetermined temperature, a heating medium heater represented by a ceramic heater, a heat medium circulating heater using a heat pump, or the like was used. A heat treatment is mentioned. In the case of these configurations, the substrate 1 can be disposed inside the film formation table. In addition, for example, a method of irradiating the surface of the substrate 1 (the multilayer reflective film 2 and the protective film 3) with a flash lamp, ultraviolet light, electromagnetic waves, or the like may be applied.
It is necessary to close the opening / closing gate 23 before starting the vacuum decompression in the sputtering chamber 21 at the latest. In order to reduce the inflow of particles from the clean room into the sputtering chamber 21, it is desirable to close the open / close gate 23 immediately after the substrate 1 is loaded and installed.

  The timing of operating the heating device is to evaporate the solidified material that causes high oxide defects on the surface of the substrate 1 (multilayer reflective film 2, protective film 3) before the start of sputtering film formation in the sputtering chamber 21, Any stage can be used as long as high oxide defects can be prevented. Desirably, before the process of depressurizing the inside of the sputtering chamber 21 to be evacuated to a predetermined degree of vacuum is completed so that the gas in which the solidified material has evaporated in the sputtering chamber 21 can be surely removed. Should be activated. In order to ensure that the surface of the substrate 1 (the multilayer reflective film 2 and the protective film 3) is at a predetermined temperature or higher during evacuation in the sputter chamber 21, the heating device is operated before evacuation is started. It is preferable.

  Note that in one aspect of the sputtering apparatus to which the third embodiment is applied, a heating apparatus is provided in the sputtering chamber 21 and the substrate 1 is heated in the sputtering chamber 21. The substrate 1 is heated in advance so that the surface of the substrate 1 (the multilayer reflective film 2 and the protective film 3) is at a predetermined temperature or higher with a certain heating device, and then carried into the sputtering chamber 21 by the transfer device 22 and installed. There may be.

[Fourth Embodiment]
In the fourth embodiment of the method of manufacturing a multilayer reflective film-coated substrate or a reflective mask blank according to the present invention, the process of exhausting the gas in the decompression chamber of the sputtering apparatus in which the heated substrate is installed to reduce the vacuum The substrate is taken out from the decompression chamber, transported in a vacuum, and placed in a sputtering chamber that has been decompressed in vacuum. A multilayer reflective film (protective film or absorber film) is formed on the substrate by sputtering in the sputtering chamber. The steps to be performed are performed in this order.

  Here again, using the sputtering apparatus 30 shown in FIG. 3 described above, in one aspect of the sputtering apparatus to which the fourth embodiment is applied, the substrate 1 is heated in the decompression chamber (load lock chamber) 34. It is the structure of the sputtering device provided with this heating device. In this case, the sputtering apparatus 30 carries the substrate 1 in the atmosphere into the decompression chamber 34 by the transfer device 32, closes the open / close gate 35, operates the heating device, and operates the multilayer reflective film 2 (protection) on the substrate 1. Heating is performed until the outermost surface on the side on which the film 3 or the absorber film 4) is formed is equal to or higher than the predetermined temperature as in the third embodiment. And the vacuum pressure reduction which exhausts the gas in the decompression chamber 34 is performed, and it is set as the predetermined degree of vacuum. Subsequent processes are the same as those of the sputtering apparatus 30 to which the second embodiment is applied.

  As described above, when the vacuum in the decompression chamber 34 is reduced, the surface of the substrate 1 (the multilayer reflective film 2 and the protective film 3) is set to a temperature at which a solidified material such as ice or dry ice evaporates. Therefore, after the inside of the decompression chamber 34 reaches a predetermined degree of vacuum and the vacuum decompression is finished, the adhesion of the solidified substance to the surface of the substrate 1 (the multilayer reflective film 2 and the protective film 3) can be suppressed more reliably than before. . Further, since the substrate 1 is transported and installed to the sputter chamber 31 where the vacuum is reduced to a predetermined degree of vacuum without opening to the atmosphere, the solidified substance is not removed even during the period from when the substrate 1 is installed in the sputter chamber 31. Adhesion can be suppressed. Therefore, even when the multilayer reflective film 2 and the protective film 3 are formed in the sputtering chamber 31 by the sputtering method, the generation of high oxide defects caused by solidified substances such as ice and dry ice can be reliably suppressed. Further, even when the absorber film 4 is formed by the sputtering method, generation of high oxide defects caused by the solidified substance is within an allowable range (high oxide defects having a size of 35 nm or more and less than 150 nm are transferred pattern regions. 10 or less) can be reliably suppressed.

The heating apparatus for setting the outermost surface of the substrate 1 to a predetermined temperature is the same as that of one form of the sputtering apparatus to which the third embodiment is applied.
The timing of operating the heating device is high oxidation on the surface of the substrate 1 (multilayer reflective film 2, protective film 3) until the vacuum pressure reduction (evacuation) until the predetermined vacuum degree in the decompression chamber 34 is completed. Any stage may be used as long as it can evaporate the solidified substance that causes the generation of physical defects and prevent the generation of high oxide defects. In order to ensure that the surface of the substrate 1 (the multilayer reflective film 2 and the protective film 3) is at a predetermined temperature or higher during evacuation in the decompression chamber 34, the heating device is operated before evacuation is started. It is preferable.

In addition, in one aspect of the sputtering apparatus to which the fourth embodiment is applied, a heating device is provided in the decompression chamber 34 and the substrate 1 is heated in the decompression chamber 34. The substrate 1 is heated in advance so that the surface of the substrate 1 (the multilayer reflective film 2 and the protective film 3) is at a predetermined temperature or higher by the heating device in FIG. It may be.
In the manufacturing method of the mask blank according to the fourth embodiment in the sputtering apparatus 30, since the inside of the sputtering chamber 31 is not normally opened to the atmosphere, particles, contaminants, and the like in the clean room chamber are in the sputtering chamber 31. Intrusion can be suppressed.

  In the sputtering apparatus 30 as well, as in the third embodiment, heating is performed so that the outermost surface becomes a predetermined temperature or higher, instead of performing vacuum decompression when the substrate 1 is placed in the decompression chamber 34. Even when the substrate 1 is placed in the sputter chamber 31 and is vacuum-depressed, the generation of solidified substances such as ice and dry ice is suppressed, and the multilayer reflective film 2 (protective film 3 or With respect to the suppression of the generation of high oxide defects in the absorber film 4), the same effect as in the third embodiment can be obtained.

Another aspect of the sputtering apparatus to which the fourth embodiment is applied will be described using the multi-chamber sputtering apparatus 40 shown in FIG.
In the sputtering apparatus 40 to which the fourth embodiment is applied, as in the case of the sputtering apparatus 30 to which the fourth embodiment is similarly applied, the substrate 1 is heated in the decompression chamber (load lock chamber) 44A. It is the structure of the sputtering device provided with this heating device. In this case, the sputtering apparatus 40 carries the substrate 1 in the atmosphere into the decompression chamber 44A by the transfer device 48, closes the open / close gate 45A, operates the heating device, and activates the multilayer reflective film 2 (protection) on the substrate 1. Heating is performed until the outermost surface on the side on which the film 3 or the absorber film 4) is formed is equal to or higher than the predetermined temperature as in the third embodiment. And the vacuum pressure reduction which exhausts the gas in the decompression chamber 44A is performed, and it is set as the predetermined degree of vacuum. Subsequent processes are the same as those of the sputtering apparatus 40 to which the second embodiment is applied.

  As described above, when vacuum decompression is performed in the decompression chamber 44A, the surface of the substrate 1 (multilayer reflective film 2, protective film 3) is set to a temperature at which a solidified material such as ice or dry ice evaporates. Therefore, after the inside of the decompression chamber 44A reaches a predetermined degree of vacuum and the vacuum decompression is finished, the adhesion of the solidified substance to the surface of the substrate 1 (multilayer reflective film 2, protective film 3) can be suppressed more reliably than before. . Further, without opening the substrate 1 to the atmosphere, the substrate 1 passes through the transfer chamber 47 that is vacuum-depressed to a predetermined degree of vacuum (transported in a vacuum), and is then sputtered chamber 41A (depressurized to a predetermined degree of vacuum) ( 41B), the adhesion of the solidified substance can be suppressed even during the period until the substrate 1 is installed in the sputtering chamber 41A (41B). Therefore, even if the multilayer reflective film 2 and the protective film 3 are formed by sputtering in the sputtering chamber 41A (41B), generation of high oxide defects caused by solidified substances such as ice and dry ice is reliably suppressed. it can. Further, even when the absorber film 4 is formed by the sputtering method, generation of high oxide defects caused by the solidified substance is within an allowable range (high oxide defects having a size of 35 nm or more and less than 150 nm are transferred pattern regions. 10 or less) can be reliably suppressed.

The heating apparatus for setting the outermost surface of the substrate 1 to a predetermined temperature is the same as that of the sputtering apparatus 30 to which the fourth embodiment is applied.
The timing of operating the heating device is high oxidation on the surface of the substrate 1 (multilayer reflective film 2, protective film 3) until the vacuum pressure reduction (evacuation) until the predetermined vacuum degree is reached in the decompression chamber 44A. Any stage may be used as long as it can evaporate the solidified substance that causes the generation of physical defects and prevent the generation of high oxide defects. In order to ensure that the surface of the substrate 1 (multilayer reflective film 2, protective film 3) is at a predetermined temperature or higher during evacuation in the decompression chamber 44A, the heating device is operated before evacuation is started. It is preferable.

In the sputtering apparatus 40 to which the fourth embodiment is applied, a heating device is provided in the decompression chamber 44A to heat the substrate 1 in the decompression chamber 44A, but it is outside the decompression chamber 44A. The substrate 1 is heated in advance so that the surface of the substrate 1 (the multilayer reflective film 2 and the protective film 3) is equal to or higher than a predetermined temperature by a heating device, and is then carried into and installed in the decompression chamber 44A by the transfer device 48. May be.
In the mask blank manufacturing method according to the fourth embodiment in the sputtering apparatus 40, the inside of the sputtering chambers 41A and 41B and the transfer chamber 47, which is the transfer path of the substrate 1, are not normally opened to the atmosphere. In addition, it is possible to prevent particles, contaminants, and the like in the clean room from entering the sputtering chambers 41A and 41B and the transfer chamber 47.

  In this sputtering apparatus 40 as well, as in the third embodiment, heating is performed so that the outermost surface is equal to or higher than a predetermined temperature, instead of performing vacuum decompression when the substrate 1 is placed in the decompression chamber 44A. Even if the substrate 1 being placed is placed in the sputtering chamber 41A (41B) or in the stage where it is in the transfer chamber 47, the generation of solidified substances such as ice and dry ice is suppressed or caused by this. The effect equivalent to that of the third embodiment can be obtained for the suppression of the generation of high oxide defects in the multilayer reflective film 2 (protective film 3 or absorber film 4).

FIG. 1 is a schematic sectional view showing an embodiment of a reflective mask blank obtained by the present invention.
As shown in FIG. 1, the reflective mask blank 10 has a structure in which a multilayer reflective film 2 is formed on a substrate 1 and layers of a protective film 3 and an absorber film 4 are formed thereon. In the configuration shown in FIG. 1, a configuration in which the multilayer reflective film 2 is formed on the substrate 1 (a configuration without the protective film 3 and the absorber film 4), or a configuration in which the protective film 3 is formed thereon. Becomes a substrate with a multilayer reflective film. The substrate 1 is in the range of 0 ± 1.0 × 10 ⁻⁷ / ° C. in order to prevent distortion of the pattern due to heat during exposure so as to be suitable as a reflective mask blank substrate using EUV light as exposure light. Among them, those having a low thermal expansion coefficient within the range of 0 ± 0.3 × 10 ⁻⁷ / ° C. are more preferable. As a material having a low thermal expansion coefficient in this range, if for example, an amorphous glass, _SiO 2 -TiO ₂ type glass substrate was added TiO ₂ within the range of about to SiO ₂ for example 5 to 10% by weight may preferably be mentioned .

The substrate 1 is a substrate having high smoothness and flatness in order to obtain high reflectivity and high transfer accuracy so as to be suitable as a glass substrate for a reflective mask blank that uses EUV light as exposure light. preferable. In particular, it is preferable to have a smooth surface of 0.150 nm Rq or less (smoothness in a 10 μm square area) and a flatness of 50 nm or less (flatness in a 142 mm square area). The substrate preferably has high rigidity in order to prevent deformation of the film formed thereon due to film stress. In particular, those having a high Young's modulus of 65 GPa or more are preferable.
In addition, unit Rq which shows smoothness is a root mean square roughness, and can be measured with an atomic force microscope. Further, the flatness is a value representing the warpage (deformation amount) of the surface indicated by TIR (Total Indicated Reading), and a plane determined by the least square method with respect to the substrate surface is a focal plane, and is above the focal plane. This is the absolute value of the height difference between the highest position on the substrate surface and the lowest position on the substrate surface below the focal plane.

As described above, the multilayer reflective film 2 is a multilayer film in which elements having different refractive indexes are periodically stacked. In general, a thin film of a heavy element or a compound thereof, a thin film of a light element or a compound thereof, A multilayer film in which about 40 to 60 periods are alternately stacked is used. In particular, a multilayer film in which a high refractive index layer made of a material containing a metal that is a high refractive index material and a low refractive index layer made of a material containing silicon that is a low refractive index material are alternately laminated is preferably used. .
For example, as a multilayer reflective film for EUV light having a wavelength of 13 to 14 nm, a Mo / Si periodic laminated film in which Mo films and Si films are alternately laminated for about 40 cycles is preferably used. In addition, as a multilayer reflective film used in the EUV light region, Ru / Si periodic multilayer film, Mo / Be periodic multilayer film, Mo compound / Si compound periodic multilayer film, Si / Nb periodic multilayer film, Si / Mo / Examples include Ru periodic multilayer films, Si / Mo / Ru / Mo periodic multilayer films, and Si / Ru / Mo / Ru periodic multilayer films. The material may be appropriately selected depending on the exposure wavelength.
The multilayer reflective film 2 can be formed by depositing each layer by DC magnetron sputtering or ion beam sputtering. In the case of the Mo / Si periodic multilayer film described above, first, a Si film having a thickness of about several nm is formed using a Si target, and then a Mo film having a thickness of about several nm is formed using a Mo target. Is stacked for 40 to 60 periods, and finally a Si film is formed.

  Further, a protective film 3 having etching characteristics different from those of the absorber film 4 may be formed between the multilayer reflective film 2 and the absorber film 4. By forming the protective film 3, the outermost layer of the multilayer reflective film 2 can be prevented from being oxidized, and damage to the multilayer reflective film 2 due to etching during pattern formation of the absorber film 4 and pattern correction can be prevented. The protective film 3 can be broadly classified into a type that removes the protective film 3 immediately below a region that is etched away when a transfer pattern is formed on the absorber film 4 and a type that does not remove the protective film 3. The protective film 3 to be removed has a high function of protecting the multilayer reflective film 2 against etching at the time of pattern correction using a focused ion beam (FIB). However, since the transmittance with respect to EUV light is low, the absorber pattern is removed. It is necessary to remove the parts to be removed. An example of a material suitable for this type of protective film 3 is a chromium-based material containing chromium. In particular, since a buffer film made of a chromium-based material has high smoothness, the surface of the absorber film formed thereon can also have high smoothness, and pattern blur can be reduced.

Examples of the chromium-based material include chromium (Cr) alone, a material containing at least one element selected from chromium (Cr) and nitrogen (N), oxygen (O), carbon (C), and fluorine (F). can do. For example, the inclusion of nitrogen provides excellent smoothness, the inclusion of carbon improves the etching resistance of the absorber film under dry etching conditions, and the inclusion of oxygen can reduce film stress. Specifically, materials such as CrN, CrO, CrC, CrF, CrON, CrCO, and CrCON are preferred. The protective film 3 can be formed by a sputtering method such as DC sputtering, RF sputtering, or ion beam sputtering.
The thickness of the protective film 3 is preferably about 20 to 60 nm, for example, when the absorber film pattern is corrected using a focused ion beam (FIB), but the electron beam and the assist gas (XeF) _{In the} case of correcting the absorber film pattern using ₂ etc., it can be about 5 to 15 nm.

The type of protective film 3 that is not removed is relatively weak and unsuitable for protecting the multilayer reflective film 2 against etching during pattern correction using a focused ion beam (FIB), but has a high transmittance for EUV light. The part from which the absorber pattern is removed does not need to be removed. An example of a material suitable for this type of protective film 3 is a ruthenium-based material containing ruthenium.
Examples of materials suitable for this type of protective film 3 include materials such as Ru, RuNb, RuZr, RuMo, RuY, RuTi, RuLa, RuSi, and RuB. In the case of this type of protective film 3, the absorber film pattern is preferably corrected using an electron beam and an assist gas (XeF ₂ or the like). In this case, the thickness of the protective film 3 is preferably about 0.8 to 5 nm.

Next, the absorber film 4 has a function of absorbing exposure light such as EUV light. For example, tantalum (Ta) alone or a material mainly composed of Ta can be preferably used. The crystalline state of the absorber film 4 preferably has an amorphous or microcrystalline structure from the viewpoint of smoothness and flatness.
As a material having Ta as a main component, a material containing Ta and B, a material containing Ta and N, a material containing Ta and B and further containing at least one of O and N, a material containing Ta and Si, Ta Material containing Si and N, Material containing Ta and Ge, Material containing Ta, Ge and N, Material containing Ta and Hf, Material containing Ta, Hf and N, Material containing Ta and Zr, Ta and Zr A material containing N and N can be used. By adding B, Si, Ge or the like to Ta, an amorphous material can be easily obtained and the smoothness can be improved. Further, when N or O is added to Ta, resistance to oxidation is improved, so that an effect that stability with time can be improved is obtained.

Among these, as a particularly preferable material, for example, a material containing Ta and B (composition ratio Ta / B is in the range of 8.5 / 1.5 to 7.5 / 2.5), Ta, B and N are included. Materials (N is 5 to 30 atomic%, and B is 10 to 30 atomic% when the remaining components are 100). In the case of these materials, a microcrystalline or amorphous structure can be easily obtained, and good smoothness and flatness can be obtained.
Such an absorber film 4 containing Ta alone or Ta as a main component is preferably formed by a sputtering method such as magnetron sputtering. For example, in the case of a TaBN film, a target containing tantalum and boron can be used and a film can be formed by a sputtering method using an argon gas to which nitrogen is added.

Examples of the absorber film 4 other than a material mainly composed of Ta include materials such as WN, TiN, and Ti.
The thickness of the absorber film 4 may be a thickness that can sufficiently absorb, for example, EUV light as exposure light, but is usually about 30 to 100 nm. The absorber film 4 may have a laminated structure of a plurality of layers having different materials and compositions.

  Even in the case of a reflective mask that applies EUV light to exposure light, the inspection light used for pattern inspection is often light having a longer wavelength than EUV light having a wavelength of 193 nm, 257 nm, or the like. In order to deal with long-wavelength inspection light, it is necessary to reduce the surface reflection of the absorber film. In this case, the absorber film 4 may have a structure in which an absorber layer mainly having a function of absorbing EUV light and a low reflection layer mainly having a function of reducing surface reflection with respect to inspection light are laminated from the substrate side. . As the low reflection layer, when the absorber layer is a material mainly composed of Ta, a material containing O in Ta or TaB or a material containing N is preferable.

The reflective mask blank may be in a state where a resist film for forming a predetermined transfer pattern is formed on the absorber film 4.
The following aspects are mentioned as a reflective mask obtained using the said reflective mask blank.
(1) A reflective mask in which a protective film is formed on a multilayer reflective film formed on a substrate, and an absorber film pattern having a predetermined transfer pattern is formed on the protective film.
(2) A reflective mask in which a protective film having a predetermined transfer pattern and an absorber film pattern are formed on a multilayer reflective film formed on a substrate.
(3) A reflective mask in which an absorber film pattern having a predetermined transfer pattern is formed on a multilayer reflective film formed on a substrate (when no protective film is provided).

Hereinafter, the embodiment of the present invention will be described more specifically with reference to examples.
Example 1
The substrate to be used is a SiO ₂ —TiO ₂ glass substrate (6 inch square, thickness 6.35 mm). This substrate has a thermal expansion coefficient of 0.2 × 10 ⁻⁷ / ° C. and a Young's modulus of 67 GPa.
The end face of this glass substrate is chamfered and ground, and the glass substrate that has been subjected to rough polishing treatment with a polishing liquid containing cerium oxide abrasive grains is set on a carrier of a double-side polishing apparatus, and colloidal silica abrasive grains are added to the polishing liquid. Using the alkaline aqueous solution containing, precision polishing was performed under predetermined polishing conditions. After the precision polishing, a predetermined cleaning process was performed.

As described above, a plurality of glass substrates for EUV reflective mask blanks were produced.
Using the defect inspection apparatus (M7360, manufactured by Lasertec Co., Ltd.) using a laser interference confocal optical system, the main surface of the obtained glass substrate is subjected to defect inspection for convex defects and concave defects having a size of 30 nm or more. Ten glass substrates on which no defects were detected were selected.

Next, the multilayer reflective film 2 and the protective film 3 were formed on the selected EUV reflective mask blank glass substrate 1 by using the sputtering apparatus (ion beam sputtering apparatus) shown in FIG.
The sputtering apparatus includes a decompression chamber (load lock chamber) 34 and a sputtering chamber 31 as shown in FIG. First, the open / close gate 35 is opened, the substrate 1 is carried into the decompression chamber 34 by the transfer robot (transfer device) 32, and the open / close gate 35 is closed. Next, while exhausting the gas in the decompression chamber 34 (air in the clean room), nitrogen gas was supplied, and the gas in the decompression chamber 34 was replaced with nitrogen gas (a gas not containing moisture and carbon dioxide). Thereafter, vacuum decompression in the decompression chamber 34 was started. When the decompression in the decompression chamber 34 is completed, the open / close gate 33 is opened, the substrate 1 is transferred from the decompression chamber 34 into the sputtering chamber 31 having the same degree of vacuum, and is set on the film forming stage with an electrostatic chuck. Formation of the multilayer reflective film 2 by the ion beam sputtering method was started.

As the multilayer reflective film 2 formed on the substrate 1, a Mo film / Si film periodic multilayer reflective film was employed in order to make the multilayer reflective film 2 suitable for the exposure light wavelength band of 13 to 14 nm. That is, the multilayer reflective film was formed by alternately laminating on the substrate 1 by the ion beam sputtering method using a Mo target and a Si target. The Si film was 4.2 nm, the Mo film was 2.8 nm, and this was taken as one period. After 40 periods were laminated, the Si film was formed to 4.2 nm.
Further, in the same sputtering chamber, a protective film 3 having a film thickness of 2.5 nm was formed on the multilayer reflective film 2 by ion beam sputtering using a mixed target of ruthenium (Ru) and niobium (Nb).
A substrate with a multilayer reflective film was thus obtained. When the reflectance of this multilayer reflective film 2 was measured with EUV light of 13.5 nm at an incident angle of 6.0 degrees, the reflectance was 65.9%.

  In the manner as described above, ten substrates with a multilayer reflective film in which the multilayer reflective film 2 and the protective film 3 were formed on the substrate 1 were produced. Using the same 30 nm sensitivity defect inspection apparatus (M7360, manufactured by Lasertec Corp.) as above, the surface of the protective film 3 of the obtained 10 multilayer reflective film-coated substrates was used for convex defects and concave shapes having a size equivalent to 30 nm or more. Defect inspection was performed for defects. As a result, in any substrate with a multilayer reflective film, the number of defects of less than 150 nm was zero. This result can also be said that the multilayer reflective film 2 under the protective film 3 also has 0 defects less than 150 nm.

  Next, in the same procedure, 10 substrates with a multilayer reflective film free from convex defects and concave defects of less than 150 nm were prepared. Then, the absorber film 4 was formed by DC sputtering using a multi-chamber type sputtering apparatus (sputtering apparatus) shown in FIG.

  The sputtering apparatus includes decompression chambers (load lock chambers) 44A and 44B, a transfer chamber (transfer chamber) 47, and sputtering chambers 41A and 41B as shown in FIG. First, the open / close gate 45A is opened, and the substrate (here, a substrate with a multilayer reflective film) 1 is carried into the decompression chamber 44A by the transfer robot (transfer device) 48, and the open / close gate 45A is closed. Next, dry air is supplied while exhausting the gas in the decompression chamber 44A (air in the clean room), and the gas in the decompression chamber 44A is replaced with dry air. Then, after completing the replacement, vacuum decompression in the decompression chamber 44A was started. When the vacuum decompression in the decompression chamber 44A is completed, the open / close gates 43A and 46A are opened, and the substrate 1 is transferred from the decompression chamber 44A through the transport chamber 47 having the same degree of vacuum by the transport robot 42 into the sputter chamber 41A. Then, the gates 43A and 46A are closed on the film formation table. Here, sputtering film formation of the absorber film 4 was started.

A mixed target of tantalum (Ta) and boron (B) (atomic% ratio Ta: B = 80: 20) is used as a sputtering target, and a mixed gas of xenon (Xe) and nitrogen (N ₂ ) is contained in the sputtering chamber 41A ( A flow rate ratio Xe: N ₂ = 13: 6) was introduced as a sputtering gas, and a lower layer of the absorber film 4 made of TaBN having a film thickness of 50 nm was formed on the protective film 3 by a DC sputtering method. Subsequently, the gas in the sputtering chamber 41A is exhausted, and a mixed gas of argon (Ar) and oxygen (O ₂ ) (flow rate ratio: Ar: O ₂ = 58: 32) is newly introduced as a sputtering gas, and a DC sputtering method is performed. Thus, the upper layer (low reflection layer) of the absorber film 4 made of TaBO having a thickness of 15 nm was formed, and the absorber film 4 made of a stacked structure of TaBN and TaBO was formed.

  As described above, 10 reflective mask blanks 10 in which the multilayer reflective film 2, the protective film 3, and the absorber film 4 were laminated on the substrate 1 were produced. Using the same 30 nm-sensitivity defect inspection apparatus (M7360, manufactured by Lasertec Corporation), the surface of the 10 reflective mask blanks thus obtained is used to form convex defects and concaves having a size of 30 nm or more. Defect inspection was performed for defects. As a result, one reflective mask blank 10 was detected in which the number of defects of less than 150 nm was detected (one convex defect and one concave defect).

  For the reflective mask blank 10 in which defects of less than 150 nm were detected, SEM observation, cross-sectional TEM observation, and EDX (Energy Dispersive X-ray spectroscopy) analysis were performed on all the defects from above the film. As a result of SEM observation, both the convex defect and the concave defect of less than 150 nm were almost circular in plan view with a diameter of about 70 nm in the measurement size of SEM. Subsequently, as a result of cross-sectional TEM observation, a convex defect of less than 150 nm is a substantially spherical shape having a high whiteness of about 50 nm in diameter from the surface of the protective film 3 of the absorber film 4 to the surface layer side of the absorber film in the cross-sectional TEM image. It was found that the core had a cross-sectional shape in which convex defects expanded concentrically from there. On the other hand, the concave defect of less than 150 nm has a high whiteness portion from the surface side of the protective film 3 of the absorber film 4 to the surface layer side of the absorber film in the cross-sectional TEM image, and the convex defect collapses. It turned out to be a concave cross section like that.

  Further, from the result of EDX analysis, a convex defect of less than 150 nm or a portion having a high whiteness of a concave defect is detected by using Ta, B, N, and O as main components, and a material that forms the lower layer of the absorber film 4 Were found to be oxidized high oxide defects. These convex defects and concave defects all indicate that there is a high possibility that the solidified product having a high oxygen concentration such as ice or dry ice is attached to the surface of the protective film 3. Yes. However, both convex defects and concave defects are formed only on the absorber film 4 and the total number of defects is as small as two, and the multilayer reflective film 2 and the protective film 3 are formed normally. Therefore, it was possible to produce a reflective mask sufficiently by using a mask defect correction technique.

  A resist film is formed by spin coating on the absorber film 4 of the reflective mask blank 10 in which convex defects and concave defects having a size of less than 150 nm are not detected in the defect inspection, and the absorber is formed by a conventional mask manufacturing process. A reflective mask having a transfer pattern of the DRAM hp 45 nm generation on the film 4 was produced. When the mask pattern inspection of the obtained reflective mask was performed, it was confirmed that the DRAM hp 45 nm generation pattern in the semiconductor design rule was formed as designed.

  Subsequently, the reflective mask was placed on the mask stage of the exposure apparatus of the EUV light source by an electrostatic chuck, and the transfer pattern was exposed and transferred to the resist film on the wafer. Further, a resist film on the wafer was developed, a resist pattern was formed, dry etching was performed using the resist pattern as a mask, and a DRAM hp45 nm generation circuit pattern was formed on the thin film on the wafer. When the defect inspection of the circuit pattern was performed, it was confirmed that the circuit pattern had no wiring short circuit or disconnection, and that the design pattern (transfer pattern) was transferred with high accuracy.

(Comparative example)
In the same manner as in Example 1, a plurality of reflective mask blank glass substrates were produced.
Using the same defect inspection apparatus (M7360, manufactured by Lasertec Co., Ltd.) as above, the main surface of the obtained glass substrate is inspected for convex defects and concave defects having a size equivalent to 30 nm or more, and these defects are detected. Ten glass substrates not selected were selected.

Next, the multilayer reflective film 2 and the protective film 3 were formed by sputtering on the selected glass substrate 1 using the sputtering apparatus (ion beam sputtering apparatus) shown in FIG.
The procedure up to the completion of the formation of the multilayer reflective film 2 and the protective film 3 is substantially the same as in Example 1. In this comparative example, after the substrate 1 is carried in and installed in the decompression chamber 34, the procedure in the decompression chamber 34 is performed. Without performing the step of replacing the gas (air in the clean room) with nitrogen gas, vacuum decompression was performed to evacuate the room gas to a predetermined degree of vacuum.

  In the manner as described above, 10 substrates with a multilayer reflective film in which the multilayer reflective film 2 and the protective film 3 were formed on the substrate 1 were produced. Using the same 30 nm sensitivity defect inspection apparatus (M7360, manufactured by Lasertec Corp.) as above, the surface of the protective film 3 of the obtained 10 multilayer reflective film-coated substrates was used for convex defects and concave shapes having a size equivalent to 30 nm or more. Defect inspection was performed for defects. As a result, defects of less than 150 nm were detected in all 10 substrates with the multilayer reflective film. In many cases, 30 or more were detected.

  For 10 substrates with a multilayer reflective film in which the number of defects less than 150 nm was detected, SEM observation, cross-sectional TEM observation, EDX (Energy DispersiveX- ray spectroscopy) analysis. As a result of SEM observation, the convex defects of less than 150 nm were almost circular in plan view with a diameter of about 90 nm as measured by the SEM. Subsequently, as a result of cross-sectional TEM observation, a convex defect having a diameter of less than 150 nm is a cross-sectional TEM image in which a substantially spherical nucleus having a high whiteness of about 50 nm in diameter exists in the vicinity of the substrate surface, from which a convex defect is concentrically formed. It turned out to be an expanding cross-sectional shape. Moreover, from the result of EDX analysis, the core part with a high whiteness of the convex defect of less than 150 nm is detected as Si, Mo, and O as main components, and the high oxide defect in which the material forming the multilayer reflective film is oxidized. It turned out to be. This indicates that there is a high possibility that a solidified product having a high oxygen concentration, such as ice or dry ice, is caused by the adhering to the main surface of the glass substrate. In this portion, deviation occurred within a range where the angle for reflecting the EUV light was unacceptable, and the reflectance was also unacceptably low. Such a substrate with a multilayer reflective film having many high oxide defects is unsuitable for producing a reflective mask blank or a reflective mask for EUV exposure light.

Next, in the same procedure as in Example 1, ten multilayer reflective film-coated substrates having no convex defects and concave defects of less than 150 nm were prepared. Then, the absorber film 4 was formed by DC sputtering using a multi-chamber type sputtering apparatus (sputtering apparatus) shown in FIG.
The procedure up to the completion of the film formation of the absorber film 4 is substantially the same as in Example 1. In this comparative example, after the substrate 1 is loaded and installed in the decompression chamber 44A, the gas in the decompression chamber 44A (in the clean room) The process of substituting the air) with dry air was not performed, and vacuum decompression was performed to evacuate the room gas to a predetermined degree of vacuum.

  As described above, 10 reflective mask blanks 10 in which the multilayer reflective film 2, the protective film 3, and the absorber film 4 were laminated on the substrate 1 were produced. Using the same 30 nm sensitivity defect inspection apparatus (M7360, manufactured by Lasertec Corporation) on the surface of the absorber film 4 of the 10 reflective mask blanks 10 thus obtained, a convex defect having a size equal to or greater than 30 nm and Defect inspection was performed on the concave defect. As a result, 11 or more defects of less than 150 nm were detected in all 10 mask blanks. In many cases, 30 or more were detected.

  For 10 reflective mask blanks in which the number of defects of less than 150 nm is detected, all defects having a size of less than 150 nm are observed by SEM observation, cross-sectional TEM observation, EDX (Energy Dispersive X-ray) from above the film at the defect location. spectroscopy). As a result of SEM observation, both the convex defect and the concave defect of less than 150 nm were substantially circular in a plan view with a diameter measured by SEM and a diameter of about 100 nm. Subsequently, as a result of cross-sectional TEM observation, convex defects of less than 150 nm are substantially spherical with a high whiteness of about 50 nm in diameter from the surface of the protective film 3 of the absorber film 4 to the surface layer side of the absorber film 4 in the cross-sectional TEM image. It has been found that the core has a cross-sectional shape in which convex defects extend concentrically from there. On the other hand, the concave defect of less than 150 nm has a high whiteness part from the surface of the protective film 3 of the absorber film 4 to the surface layer side of the absorber film 4 in the cross-sectional TEM image, and the convex defect collapses. It turned out to be a concave cross section like that.

  Further, from the result of EDX analysis, a convex defect of less than 150 nm or a portion having a high whiteness of a concave defect is detected by using Ta, B, N, and O as main components, and a material that forms the lower layer of the absorber film 4 Were found to be oxidized high oxide defects. These convex defects and concave defects all indicate that there is a high possibility that it is caused by a high oxygen concentration coagulum such as ice or dry ice adhering to the surface of the protective film. . Such high oxide defects can be said to be unsuitable for producing a reflective mask since the absorption rate of the absorber film 4 with respect to EUV light is reduced.

  Next, a reflective mask having a transfer pattern of the DRAM hp 45 nm generation on the absorber film 4 was produced from the manufactured reflective mask blank in the same procedure as in Example 1. When the mask pattern inspection of the obtained reflective mask was performed, a pattern defect was caused due to insufficient absorption rate of the absorber film. Furthermore, due to the fact that high oxide defects have been formed inside the multilayer reflective film 2, the variation in in-plane uniformity of the surface reflectance with respect to EUV exposure light is large, and as a reflective mask for the DRAM hp45 nm generation Was unsuitable.

(Example 2)
In the same manner as in Example 1, a plurality of reflective mask blank glass substrates were produced.
Using the same defect inspection apparatus (M7360, manufactured by Lasertec Co., Ltd.) as above, the main surface of the obtained glass substrate is inspected for convex defects and concave defects having a size equivalent to 30 nm or more, and these defects are detected. Ten glass substrates not selected were selected.

Next, the multilayer reflective film 2 and the protective film 3 were formed by sputtering on the selected glass substrate 1 using the sputtering apparatus (ion beam sputtering apparatus) shown in FIG.
The procedure up to the completion of the formation of the multilayer reflective film 2 and the protective film 3 is substantially the same as that of the first embodiment. In this second embodiment, however, the decompression chamber 34 includes a mounting table provided with a ceramic heater (heating device). The point which is installed, the point which carries in and installs the glass substrate 1 on the mounting table in the decompression chamber 34 by the transfer device 32, and the step of replacing the gas in the decompression chamber 34 (air in the clean room) with nitrogen gas. In contrast to the first embodiment, the glass substrate 1 is heated by a ceramic heater, and vacuum decompression is performed to evacuate the gas in the decompression chamber 34 (air in the clean room) to a predetermined degree of vacuum. Different. At this time, it heated so that the main surface of the glass substrate 1 might be set to 50-70 degreeC with a ceramic heater.

  In the manner as described above, ten substrates with a multilayer reflective film in which the multilayer reflective film 2 and the protective film 3 were formed on the substrate 1 were produced. The surface of the protective film 3 of the obtained 10 substrates with the multilayer reflective film was subjected to the same 30 nm sensitivity defect inspection apparatus (M7360, manufactured by Lasertec Co., Ltd.) as above. Defect inspection was performed for defects. As a result, in any substrate with a multilayer reflective film, the number of defects of less than 150 nm was zero. This result can also be said that the multilayer reflective film 2 under the protective film 3 also has 0 defects less than 150 nm.

Next, in the same procedure as in this example, 10 multilayer reflective film-coated substrates having no convex defects and concave defects of less than 150 nm were prepared. Then, the absorber film 4 was formed by DC sputtering using the multi-chamber type sputtering apparatus (sputtering apparatus) 40 shown in FIG.
The procedure up to the completion of the film formation of the absorber film 4 is substantially the same as that of the first embodiment. However, in this second embodiment, after the substrate 1 is introduced into the decompression chamber 44A, the interior of the decompression chamber 44A is evacuated. When the vacuum is reduced to a predetermined degree of vacuum, the process of replacing the gas in the decompression chamber 44A (air in the clean room) with dry air is not performed, as in the case of forming the multilayer reflective film 2, and the ceramic is not performed. While heating the substrate 1 with a heater, vacuum decompression was performed so that the gas in the decompression chamber 44A (air in the clean room) was evacuated to a predetermined degree of vacuum.

  As described above, 10 reflective mask blanks 10 in which the multilayer reflective film 2, the protective film 3, and the absorber film 4 were laminated on the substrate 1 were produced. Using the same 30 nm sensitivity defect inspection apparatus (M7360, manufactured by Lasertec Corporation) on the surface of the absorber film 4 of the 10 reflective mask blanks 10 thus obtained, a convex defect having a size equal to or greater than 30 nm and Defect inspection was performed on the concave defect. As a result, in any reflective mask blank, the number of defects of less than 150 nm was zero.

  A resist film is formed by spin coating on the absorber film 4 of the reflective mask blank 10 in which convex defects and concave defects of less than 150 nm are not detected by the defect inspection, and the absorber film 4 is formed by a conventional mask manufacturing process. A reflective mask having a transfer pattern of DRAM hp45 nm generation was produced. When the mask pattern inspection of the obtained reflective mask was performed, it was confirmed that the DRAM hp 45 nm generation pattern in the semiconductor design rule was formed as designed.

  Subsequently, the reflective mask was placed on the mask stage of the exposure apparatus of the EUV light source by an electrostatic chuck, and the transfer pattern was exposed and transferred to the resist film on the wafer. Further, a resist film on the wafer was developed, a resist pattern was formed, dry etching was performed using the resist pattern as a mask, and a DRAM hp45 nm generation circuit pattern was formed on the thin film on the wafer. When the defect inspection of the circuit pattern was performed, it was confirmed that the circuit pattern had no wiring short circuit or disconnection, and that the design pattern (transfer pattern) was transferred with high accuracy.

(Example 3)
In the same manner as in Example 1, a plurality of reflective mask blank glass substrates were produced.
Using the same defect inspection apparatus (M7360, manufactured by Lasertec Co., Ltd.) as above, the main surface of the obtained glass substrate is inspected for convex defects and concave defects having a size equivalent to 30 nm or more, and these defects are detected. Ten glass substrates not selected were selected.

Next, the multilayer reflective film 2 and the protective film 3 were formed by sputtering on the selected glass substrate 1 using the sputtering apparatus (ion beam sputtering apparatus) shown in FIG.
The procedure up to the completion of the formation of the multilayer reflective film 2 and the protective film 3 is substantially the same as that of the first embodiment, but in this second embodiment, a ceramic heater (heating device) disposed outside the decompression chamber 34 is used. The substrate 1 is placed on a mounting table including the substrate 1, heated until the main surface of the substrate 1 reaches 90 ° C., and then transported and installed in the decompression chamber 34 by the transport device 32, the gas in the decompression chamber 34 (in the clean room) The step of substituting nitrogen gas for air) is performed, and the vacuum pressure reduction is performed to evacuate the gas in the decompression chamber 34 (air in the clean room) to a predetermined degree of vacuum while the substrate 1 is not cooled. Very different from Example 1.

  In the manner as described above, ten substrates with a multilayer reflective film in which the multilayer reflective film 2 and the protective film 3 were formed on the substrate 1 were produced. The surface of the protective film 3 of the obtained 10 substrates with the multilayer reflective film was subjected to the same 30 nm sensitivity defect inspection apparatus (M7360, manufactured by Lasertec Co., Ltd.) as above. Defect inspection was performed for defects. As a result, in any substrate with a multilayer reflective film, the number of defects of less than 150 nm was zero. This result can also be said that the multilayer reflective film 2 under the protective film 3 also has 0 defects less than 150 nm.

Next, in the same procedure as in this example, 10 multilayer reflective film-coated substrates having no convex defects and concave defects of less than 150 nm were prepared. Then, the absorber film 4 was formed by DC sputtering using the multi-chamber type sputtering apparatus (sputtering apparatus) 40 shown in FIG.
The procedure up to the completion of the film formation of the absorber film 4 is substantially the same as that of the first embodiment. However, in this third embodiment, when the inside of the decompression chamber 44A is made to have a predetermined degree of vacuum by vacuum decompression by evacuation. As in the case of forming the multilayer reflective film 2, the substrate 1 is heated by a mounting table provided with a ceramic heater (heating device) arranged outside the decompression chamber 44A and then transferred into the decompression chamber 44A. The step of installing and replacing the gas in the decompression chamber 44A (air in the clean room) with dry air was not performed, and vacuum decompression was performed to evacuate the gas in the decompression chamber 44A to a predetermined degree of vacuum.

  As described above, 10 reflective mask blanks 10 in which the multilayer reflective film 2, the protective film 3, and the absorber film 4 were laminated on the substrate 1 were produced. Using the same 30 nm sensitivity defect inspection apparatus (M7360, manufactured by Lasertec Corporation) on the surface of the absorber film 4 of the 10 reflective mask blanks 10 thus obtained, a convex defect having a size equal to or greater than 30 nm and Defect inspection was performed on the concave defect. As a result, in any reflective mask blank, the number of defects of less than 150 nm was zero.

  A resist film is formed by spin coating on the absorber film 4 of the reflective mask blank 10 in which convex defects and concave defects of less than 150 nm are not detected by the defect inspection, and the absorber film 4 is formed by a conventional mask manufacturing process. A reflective mask having a transfer pattern of DRAM hp45 nm generation was produced. When the mask pattern inspection of the obtained reflective mask was performed, it was confirmed that the DRAM hp 45 nm generation pattern in the semiconductor design rule was formed as designed.

  Subsequently, the reflective mask was placed on the mask stage of the exposure apparatus of the EUV light source by an electrostatic chuck, and the transfer pattern was exposed and transferred to the resist film on the wafer. Further, a resist film on the wafer was developed, a resist pattern was formed, dry etching was performed using the resist pattern as a mask, and a DRAM hp45 nm generation circuit pattern was formed on the thin film on the wafer. When the defect inspection of the circuit pattern was performed, it was confirmed that the circuit pattern had no wiring short circuit or disconnection, and that the design pattern (transfer pattern) was transferred with high accuracy.

  As described above, according to the present invention, regarding the multilayer reflective film and the protective film, the number of high oxide defects having a size of less than 150 nm containing more oxygen than the surroundings in the film is set to 0 (zero). For example, it is possible to obtain a substrate with a multilayer reflective film that requires a very high level of defect quality. In addition, with respect to the absorber film, the number of high oxide defects having a size of 35 nm or more and less than 150 nm containing more oxygen than the surroundings in the film can be greatly reduced, for example, a very high level of defect quality. The required reflective mask blank is obtained.

DESCRIPTION OF SYMBOLS 1 Substrate 2 Multilayer reflective film 3 Protective film 4 Absorber film 10 Reflective mask blanks 20, 30, 40 Sputter devices 21, 31, 41A, 41B Sputter chambers 22, 32, 42, 48 Transport devices 23, 33, 35 Open / close gate 34, 44A, 44B Decompression chambers 43A, 43B, 45A, 45B, 46A, 46B Open / close gate 47 Transfer chamber

Claims (14)

A multilayer reflective film in which a glass substrate is carried into a sputtering apparatus, and a multilayer reflective film is formed by alternately laminating a layer made of a metal-containing material and a layer made of a silicon-containing material on the glass substrate by sputtering. In the manufacturing method of the attached substrate,
In order that the multilayer reflective film does not have a high oxide defect having a size of less than 150 nm containing oxygen more than its surroundings in the film at least in a region that is exposed to exposure light.
Replacing the gas in the sputtering chamber of the sputtering apparatus on which the glass substrate is installed with a gas not containing moisture and carbon dioxide;
Evacuating the substituted gas from the sputtering chamber and reducing the vacuum,
A method for producing a substrate with a multilayer reflective film, wherein the step of forming the multilayer reflective film on a glass substrate by a sputtering method is performed in this order in the sputtering chamber. A multilayer reflective film in which a glass substrate is carried into a sputtering apparatus, and a multilayer reflective film is formed by alternately laminating a layer made of a metal-containing material and a layer made of a silicon-containing material on the glass substrate by sputtering. In the manufacturing method of the attached substrate,
In order that the multilayer reflective film does not have a high oxide defect having a size of less than 150 nm containing oxygen more than its surroundings in the film at least in a region that is exposed to exposure light.
A step of replacing the gas in the vacuum chamber of the sputtering apparatus on which the glass substrate is installed with a gas not containing moisture and carbon dioxide,
Exhausting the substituted gas from the decompression chamber to reduce the vacuum;
Removing the glass substrate from the decompression chamber and transporting it in a vacuum;
A method for producing a substrate with a multilayer reflective film, wherein the step of forming the multilayer reflective film on a glass substrate by a sputtering method is performed in this order in the sputtering chamber. The high oxide defects, multilayer reflective film coated substrate manufacturing method according to claim 1 or 2, wherein the a defect that occurs in the vicinity of the interface between the glass substrate in the multilayer reflective film. The high oxide defects, manufacturing method of the substrate with multilayer reflective film according to any one of claims 1 to 3, characterized in that a defect of substantially spherical. A substrate on which a multilayer reflective film is formed is carried into a sputtering apparatus, and a single-layer or multiple-layer protective film made of a material containing at least one of metal and silicon is formed on the multilayer reflective film by sputtering. In the method of manufacturing a substrate with a multilayer reflective film,
In order that the protective film does not have a high oxide defect having a size of less than 150 nm containing oxygen more than its surroundings in the film, at least in a region subjected to exposure light irradiation,
Replacing the gas in the sputtering chamber of the sputtering apparatus on which the substrate is installed with a gas not containing moisture and carbon dioxide;
Evacuating the substituted gas from the sputtering chamber and reducing the vacuum,
A method for producing a substrate with a multilayer reflective film, wherein the step of forming at least one layer of the protective film or the plurality of protective films on the multilayer reflective film by a sputtering method is performed in this order in the sputtering chamber. . A substrate on which a multilayer reflective film is formed is carried into a sputtering apparatus, and a single-layer or multiple-layer protective film made of a material containing at least one of metal and silicon is formed on the multilayer reflective film by sputtering. In the method of manufacturing a substrate with a multilayer reflective film,
In order that the protective film does not have a high oxide defect having a size of less than 150 nm containing oxygen more than its surroundings in the film, at least in a region subjected to exposure light irradiation,
Replacing the gas in the vacuum chamber of the sputtering apparatus on which the substrate is installed with a gas not containing moisture and carbon dioxide;
Exhausting the substituted gas from the decompression chamber to reduce the vacuum;
Removing the substrate from the decompression chamber, transporting the substrate in a vacuum, and placing the substrate in a vacuum chamber with reduced pressure;
A method for producing a substrate with a multilayer reflective film, wherein the step of forming at least one layer of the protective film or the plurality of protective films on the multilayer reflective film by a sputtering method is performed in this order in the sputtering chamber. . The gas that does not contain moisture and carbon dioxide is any gas of rare gas, hydrogen gas, nitrogen gas, fluorine gas, and chlorine gas, or a mixed gas of two or more gases selected from these gases. The manufacturing method of the board | substrate with a multilayer reflective film in any one of Claims 1 thru | or 6 . The substrate is a multilayer reflective film coated substrate according to any one of claims 1 to 7, characterized in that it consists of low thermal expansion glass with a thermal expansion coefficient in the range of 0 ± 1.0 × 10 -7 ^/ ℃ Manufacturing method. The multilayer reflection film, a manufacturing method of a substrate with multilayer reflective film according to any one of claims 1 to 8, characterized in that it is formed by ion beam sputtering. Material containing said metal is molybdenum or molybdenum compounds, materials containing the silicon, the multilayer reflective film coated substrate according to any one of claims 1 to 9, characterized in that the silicon or silicon compound Manufacturing method . Reflections and forming an absorber film in claims 1 to 10 or a multilayer reflection film on the multilayer reflective film coated substrate produced by the production method of the multilayer reflective film coated substrate according or a protective film on the Mold mask blank manufacturing method. A substrate on which a multilayer reflective film is formed is carried into a sputtering apparatus, and a single-layer or multiple-layer absorber film made of a material containing at least one of metal and silicon is formed on the multilayer reflective film by sputtering. In the manufacturing method of the reflective mask blank to
The absorber film contains 10 or less high oxide defects having a size of 35 nm or more and less than 150 nm containing more oxygen than the surroundings in the film.
Replacing the gas in the sputtering chamber of the sputtering apparatus on which the substrate is installed with a gas not containing moisture and carbon dioxide;
Evacuating the substituted gas from the sputtering chamber and reducing the vacuum,
In the sputtering chamber, a process of forming at least one layer of the absorber film or the plurality of absorber films on the multilayer reflective film by a sputtering method is performed in this order. Method. A substrate on which a multilayer reflective film is formed is carried into a sputtering apparatus, and a single-layer or multiple-layer absorber film made of a material containing at least one of metal and silicon is formed on the multilayer reflective film by sputtering. In the manufacturing method of the reflective mask blank to
The absorber film contains 10 or less high oxide defects having a size of 35 nm or more and less than 150 nm containing more oxygen than the surroundings in the film.
Replacing the gas in the vacuum chamber of the sputtering apparatus on which the substrate is installed with a gas not containing moisture and carbon dioxide;
Exhausting the substituted gas from the decompression chamber to reduce the vacuum;
Removing the substrate from the decompression chamber, transporting the substrate in a vacuum, and placing the substrate in a vacuum chamber with reduced pressure;
In the sputtering chamber, a process of forming at least one layer of the absorber film or the plurality of absorber films on the multilayer reflective film by a sputtering method is performed in this order. Method. The gas that does not contain moisture and carbon dioxide is any gas of rare gas, hydrogen gas, nitrogen gas, fluorine gas, and chlorine gas, or a mixed gas of two or more gases selected from these gases. The manufacturing method of the reflective mask blank of Claim 12 or 13 .

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