JP6627926B2 - Method for manufacturing phase shift mask blanks - Google Patents

Description

The present invention relates to a method for manufacturing a phase shift mask blank used for manufacturing a semiconductor integrated circuit and the like.

  In the field of semiconductor technology, research and development for further miniaturization of patterns are being advanced. In particular, in recent years, with the integration of large-scale integrated circuits, finer circuit patterns, finer wiring patterns, and finer contact hole patterns for interlayer wiring constituting cells have been developed. Demands are becoming ever higher. Accordingly, in the field of photomask manufacturing technology used in a photolithography process at the time of microfabrication, development of a technology for forming a finer and more accurate circuit pattern (mask pattern) has been required. Is coming.

  Generally, when a pattern is formed on a semiconductor substrate by photolithography, reduced projection is performed. Therefore, the size of the pattern formed on the photomask is about four times the size of the pattern formed on the semiconductor substrate. In today's photolithography art, the size of a circuit pattern to be drawn is much smaller than the wavelength of light used for exposure. Therefore, when the photomask pattern is formed by simply increasing the size of the circuit pattern by four times, the original shape is not transferred to the resist film on the semiconductor substrate due to the influence of light interference generated at the time of exposure. The result is.

  Therefore, the pattern formed on the photomask may have a more complicated shape than the actual circuit pattern to reduce the influence of the above-described light interference in some cases. As such a pattern shape, for example, there is a shape in which an optical proximity effect correction (OPC: Optical Proximity Correction) is performed on an actual circuit pattern. In addition, technologies such as deformed illumination, liquid immersion technology, resolution enhancement technology (RET: Resolution Enhancement Technology), and double exposure (double patterning lithography) have been applied in order to respond to finer patterns and higher precision.

  As one of RET, a phase shift method is used. The phase shift method is a method in which a pattern of a film that inverts the phase by approximately 180 ° is formed on a photomask, and the contrast is improved using light interference. As one of photomasks to which this is applied, there is a halftone phase shift mask. The halftone phase shift mask inverts the phase by approximately 180 ° on a substrate transparent to exposure light such as quartz, and forms a mask pattern of a halftone phase shift film having a transmittance that does not contribute to pattern formation. It was formed. As a halftone phase shift mask, a mask having a halftone phase shift film made of molybdenum silicide oxide (MoSiO) or molybdenum silicide oxynitride (MoSiON) has been proposed (Japanese Patent Application Laid-Open No. 7-140635). Reference 1)).

  In addition, photolithography technology has led to the use of shorter wavelength exposure light sources in order to obtain finer images. In the current state-of-the-art practical processing process, the exposure light source is a KrF excimer laser light. (248 nm) to ArF excimer laser light (193 nm). However, it has been found that the use of ArF excimer laser light of higher energy causes mask damage not seen with KrF excimer laser light. One of the problems is that when a photomask is used continuously, foreign matter-like growth defects occur on the photomask. This growth defect is called haze, and was originally thought to be caused by the growth of ammonium sulfate crystals on the surface of the mask pattern. However, it is now thought that an organic substance is involved.

  As a countermeasure against the haze problem, for example, Japanese Patent Application Laid-Open No. 2008-276002 (Patent Document 2) discloses that a growth defect that occurs when a photomask is irradiated with ArF excimer laser light for a long period of time is subjected to a predetermined step. It is shown that the photomask can be used continuously by cleaning the photomask with.

  In addition, it has been reported that as the exposure dose of ArF excimer laser light in pattern transfer increases, damage different from haze occurs in the photomask, and the pattern size of the mask changes according to the accumulated irradiation energy. (Thomas Faure et al., “Characterization of binary mask and attenuated phase shift mask blanks for 32 nm mask fabrication”, Proc. Of SPIE, vol. 7122, pp. 712209-1 to 712209-12 (Non-Patent Document 1)). This is because, when the ArF excimer laser beam is irradiated for a long time, the cumulative irradiation energy becomes large, and a layer made of a material which is considered to be an oxide of the pattern material grows outside the film pattern and the pattern width changes. It is. In addition, it has been shown that the damaged mask cannot be recovered by washing with ammonia water / hydrogen peroxide used for removing the above-mentioned haze or washing with sulfuric acid / hydrogen peroxide, and the cause is completely different. It is thought that.

  Further, according to the report by Thomas Faure et al. (Non-Patent Document 1), in a circuit pattern exposure, a halftone phase shift mask, which is a mask technique useful for extending the depth of focus, is particularly suitable for the ArF excimer laser light. It has been pointed out that deterioration due to pattern dimensional fluctuation accompanying deterioration of a transition metal silicon-based material film such as a MoSi-based material film due to irradiation (hereinafter, referred to as pattern dimensional fluctuation deterioration) is large. Therefore, in order to use an expensive photomask for a long period of time, it is necessary to take measures against pattern dimension fluctuation deterioration due to irradiation with ArF excimer laser light.

  As described in the above-mentioned report by Thomas Faure et al. (Non-patent Document 1), pattern size fluctuation deterioration due to irradiation with short-wavelength light such as ArF excimer laser light hardly occurs when light is irradiated in a dry air atmosphere. As a new measure to prevent the pattern dimension fluctuation deterioration, a method of performing exposure in dry air can be considered. However, control in a dry air atmosphere requires an additional device and additionally requires measures against static electricity, which leads to an increase in cost. Therefore, it is necessary to enable long-time exposure in a normal atmosphere (for example, a humidity of about 50%) in which the humidity is not completely removed.

  Further, in a photomask used for lithography using an ArF excimer laser beam as a light source, a transition metal silicon-based material is conventionally used in a halftone phase shift film, and a silicon-based material containing molybdenum is usually used. . The main constituent elements of this transition metal silicon-based material are a transition metal and silicon, and those containing nitrogen and / or oxygen as light elements (for example, JP-A-7-140635 (Patent Document 1)). is there. As the transition metal, molybdenum, zirconium, tantalum, tungsten, titanium, or the like is used. In particular, molybdenum is generally used (for example, JP-A-7-140635 (Patent Document 1)). In some cases (Japanese Patent Application Laid-Open No. 2004-133029 (Patent Document 3)). Also, a transition metal silicon-based material is used for the light-shielding film, and a silicon-based material containing molybdenum is usually used. However, when a photomask using such a transition metal silicon-based material is irradiated with a large amount of high-energy light, pattern dimension fluctuation is greatly deteriorated by irradiation of the high-energy light, and the service life of the photomask is required. It will be shorter.

  Irradiation of short-wavelength light such as ArF excimer laser light onto a photomask pattern of a halftone phase shift mask changes the line width of the photomask pattern used for exposure. is there. The allowable limit of the pattern width differs depending on the type of the photomask pattern, particularly the applied pattern rule. In addition, if there is a slight variation, the exposure condition can be corrected and the exposure condition of the exposure apparatus can be reset and used in some cases. However, for example, in the exposure for forming a semiconductor circuit according to a pattern rule of 22 nm, photo exposure is required. The variation of the mask pattern line width needs to be approximately ± 5 nm or less. However, when the amount of change in the pattern width is large, the amount of change may have a distribution in the plane of the photomask. Further, with further miniaturization, an extremely fine auxiliary pattern of 100 nm or less is formed on the mask. For this reason, even with the pattern miniaturization on these masks and the increase in mask processing cost due to the complexity of the mask pattern, there is a need for a halftone phase shift mask film that has extremely small pattern dimension fluctuation deterioration and can be repeatedly exposed. You.

  Further, when the halftone phase shift mask blank is used in the manufacturing process of the halftone phase shift mask, if foreign matter is present on the halftone phase shift mask blank, the foreign matter causes a pattern defect. To remove, the halftone phase shift mask blanks are cleaned many times during the halftone phase shift mask manufacturing process. Furthermore, when using a halftone phase shift mask in a photolithography process, even if there is no pattern defect in the manufactured halftone phase shift mask itself, during the photolithography process, if foreign matter adheres to the halftone phase shift mask, Since a pattern transfer failure occurs on a semiconductor substrate patterned using this, the halftone phase shift mask is also repeatedly cleaned.

  In most cases, chemical cleaning with a sulfuric acid peroxide solution, an ozone water solution, an ammonia peroxide solution, or the like is performed to remove foreign matter from the halftone phase shift mask blank or the halftone phase shift mask. Here, sulfuric acid / hydrogen peroxide is a cleaning agent having a strong oxidizing effect obtained by mixing sulfuric acid and hydrogen peroxide, and ozone water is obtained by dissolving ozone in water. Used as an alternative. In particular, ammonia peroxide is a cleaning agent obtained by mixing ammonia water and hydrogen peroxide solution, and when organic foreign substances adhered to the surface are immersed in ammonia peroxide solution, the dissolution action of ammonia and the hydrogen peroxide The organic foreign matter is separated from the surface by the oxidizing action and is separated and washed.

  Chemical cleaning with such a chemical solution is necessary to remove foreign substances such as particles and contaminants adhered to the halftone phase shift mask blanks and halftone phase shift masks, while the halftone phase shift mask blanks and half There is a possibility that the halftone phase shift film provided in the tone phase shift mask may be damaged. For example, the surface of the halftone phase shift film may be deteriorated by the chemical cleaning as described above, and the optical characteristics originally provided may be changed. Since the chemical cleaning of the phase shift mask is performed repeatedly, it is necessary to suppress the characteristic change (for example, the phase difference change) of the halftone phase shift film generated in each cleaning step as low as possible. is there.

JP-A-7-140635 JP 2008-276002 A JP-A-2004-133029 JP 2007-33469 A JP 2007-233179 A JP 2007-241065 A

Thomas Faure et al., “Characterization of binary mask and attenuated phase shift mask blanks for 32nm mask fabrication”, Proc.Of SPIE, vol. 7122, pp712209-1 to 712209-12

  A thin phase shift film is advantageous not only for pattern formation but also for reducing the three-dimensional effect. Therefore, in photolithography, a thinner film is required to form a finer pattern.

  As described above, as the phase shift film, a film containing molybdenum and silicon has been mainly used (Japanese Patent Application Laid-Open No. Hei 7-140635 (Patent Document 1)). However, in a film containing a transition metal, ArF having a wavelength of 193 nm is used. Irradiation with excimer laser light causes a large deterioration in pattern dimension fluctuation, and a film containing a transition metal causes a large change in optical characteristics due to cleaning by repeated cleaning during a mask manufacturing process and during use of the mask. These problems can be suppressed by forming the phase shift film with a silicon-based material that does not contain a transition metal.However, a phase-shift film is formed with a silicon-based material that does not contain a transition metal, particularly, a silicon-containing material that contains nitrogen. Then, when the phase shift mask is manufactured by patterning the phase shift film from the phase shift mask blanks, the flatness changes before and after the phase shift film pattern is formed. There is a problem that the above pattern position shifts and the dimensional accuracy is reduced.

The present invention has been made in order to solve the above problems, and as a phase shift film capable of responding to miniaturization of a pattern, while securing a necessary phase difference, in forming a pattern, reducing a three-dimensional effect, and the like. It is an advantageous phase shift film with a small thickness, and when forming a phase shift mask by patterning the phase shift film, there is little displacement of the pattern position and little decrease in dimensional accuracy, and excellent dimensional controllability. It is an object of the present invention to provide a method of manufacturing a phase shift mask blank having a phase shift film that provides a high quality phase shift mask blank.

  The present inventors, in order to solve the above problems, after securing the necessary phase difference as a phase shift film, the film thickness is small, when forming a phase shift film pattern forming a phase shift mask, Aiming for the development of a phase shift film with less pattern shift and lower dimensional accuracy, we conducted intensive studies on a phase shift film that does not contain a transition metal. Alternatively, silicon, formed by sputtering so as to include at least one layer of a silicon-based material composed of nitrogen and oxygen, and the formed phase shift film is heat-treated at 400 ° C. or more for 5 minutes or more to reduce the film thickness to 70 nm or less. The phase difference is 150 to 200 ° with respect to light having a wavelength of 200 nm or less, and the phase shift film is formed on the transparent substrate before forming the phase shift film on the transparent substrate. A phase shift film having a warpage change (ΔTIR) of 0.2 μm or less in absolute value within a 142 mm square in the central part of the transparent substrate surface between the existing state and a transparent substrate, and a phase shift film on the transparent substrate Between the existing state and the state after the entire phase shift film existing on the transparent substrate is removed by etching, the change amount (ΔTIR) of the warp within a 142 mm square at the center of the transparent substrate surface is 0 in absolute value. It was found that a phase shift film having a thickness of 0.2 μm or less can be formed.

  By configuring the phase shift film in this manner, a half-pitch of 50 nm or less can be formed on a substrate to be processed such as a silicon wafer by using exposure light having a wavelength of 200 nm or less using a phase shift mask having a pattern of the phase shift film. In a phase shift mask having a phase shift film pattern having a main photomask pattern having a width of about 100 to 200 nm, which is required in photolithography for forming a pattern to be transferred, the pattern shift on the phase shift mask is small. The present inventors have found that a phase shift mask blank that provides a photomask with good dimensional accuracy can be obtained, and the present invention has been accomplished.

Therefore, the present invention provides the following method for producing a phase shift mask blank.
Claim 1:
On a 152 mm square, 6.35 mm thick transparent substrate, a light having a wavelength of 200 nm or less and a phase shift film having a phase shift amount of 150 to 200 ° are provided.
The phase shift film includes at least one layer of a silicon-based material including silicon and nitrogen or a silicon-based material including silicon, nitrogen, and oxygen, has a transmittance of 3% or more and 12% or less, and has a film thickness of 70 nm or less. A method for manufacturing a phase shift mask blanks,
(1) a step of forming the phase shift film on the transparent substrate by sputtering;
(2) heat-treating the phase shift film formed on the transparent substrate at 500 ° C. to 900 ° C. for 6 hours to 24 hours ,
Step (1) of forming the phase shift film includes:
(A) On a transparent substrate, an argon gas and a nitrogen gas are introduced into a sputtering chamber by using at least one silicon target by using a sputtering apparatus to form a layer of the silicon-based material including silicon and nitrogen. And (B) using a sputtering apparatus and at least one silicon target on a transparent substrate, using an argon gas and at least one gas selected from a nitrogen gas, an oxygen gas, and a nitrogen oxide gas in a sputtering chamber. Introduced into the above, silicon, by a method comprising one or both steps of forming a layer of a silicon-based material consisting of nitrogen and oxygen,
As the above-mentioned phase shift film, the amount of change in the warp within a 142 mm square at the center of the transparent substrate surface (between before the phase shift film is formed on the transparent substrate and when the phase shift film is present on the transparent substrate) ΔTIR) is a halftone phase shift film having an absolute value of not more than 0.2 μm.
Claim 2:
2. The method according to claim 1, wherein the light having a wavelength of 200 nm or less is ArF excimer laser light.
Claim 3:
3. The method according to claim 1, wherein in the step (2) of heat-treating the phase shift film, a heat treatment temperature is 700 ° C. or less.
Claim 4:
The method according to any one of claims 1 to 3, wherein in the step (2) of heat-treating the phase shift film, the heat treatment time is 12 hours or less.
Claim 5:
The method according to any one of claims 1 to 4, wherein in the step (2) of heat-treating the phase shift film, a heat treatment atmosphere is an inert gas atmosphere or a vacuum.
Further, the present invention relates to the following phase shift mask blank, a phase shift mask, and a method of manufacturing the phase shift mask blank.
[1] A phase shift mask blank having a phase shift film having a wavelength of 200 nm or less and a phase shift amount of 150 to 200 ° on a 152 mm square, 6.35 mm thick transparent substrate,
The phase shift film includes at least one layer of a silicon-based material composed of silicon and nitrogen or a silicon-based material composed of silicon, nitrogen and oxygen, has a thickness of 70 nm or less, and has a phase shift film on a transparent substrate. Before the formation, and between the state where the phase shift film is present on the transparent substrate, the phase change amount (ΔTIR) within 142 mm square at the center of the transparent substrate surface is 0.2 μm or less in absolute value. A phase shift mask blank, wherein a shift film is formed.
[2] A phase shift mask blank having a phase shift film with a wavelength of 200 nm or less and a phase shift amount of 150 to 200 ° on a 152 mm square, 6.35 mm thick transparent substrate,
The phase shift film includes at least one layer of a silicon-based material composed of silicon and nitrogen or a silicon-based material composed of silicon, nitrogen and oxygen, has a thickness of 70 nm or less, and has a phase shift film on a transparent substrate. Between the existing state and the state after the entire phase shift film existing on the transparent substrate is removed by etching, the change amount (ΔTIR) of the warp within a 142 mm square at the center of the transparent substrate surface is 0 in absolute value. A phase shift mask blank, wherein a phase shift film having a thickness of 2 μm or less is formed.
[3] The phase shift film is a halftone phase shift film made of a silicon-based material composed of silicon and nitrogen and having a transmittance of 3% or more and less than 20% with the light having a wavelength of 200 nm or less. The phase shift mask blank according to [1] or [2].
[4] The phase shift film is a halftone phase shift film made of a silicon-based material including silicon, nitrogen and oxygen, and having a transmittance of 20% or more with the light having a wavelength of 200 nm or less. The phase shift mask blank according to [1] or [2].
[5] The method according to any one of [1] to [4], further comprising a second layer including a single layer or a plurality of layers made of a material containing chromium, on the phase shift film. Phase shift mask blanks.
[6] The second layer is a light-shielding film, a combination of a light-shielding film and an anti-reflection film, or a processing auxiliary film functioning as a hard mask in pattern formation of the phase shift film. The described phase shift mask blanks.
[7] The phase shift mask blank according to [5], further comprising a third layer composed of a single layer or a plurality of layers made of a material containing silicon, on the second layer.
[8] The second layer is a light-shielding film or a combination of a light-shielding film and an anti-reflection film, and the third layer is a processing auxiliary film functioning as a hard mask in pattern formation of the second layer. The phase shift mask blank according to [7], wherein:
[9] The second layer is a processing auxiliary film that functions as a hard mask in forming the pattern of the phase shift film and functions as an etching stopper in forming the pattern of the third layer. Is a light-shielding film or a combination of a light-shielding film and an anti-reflection film.
[10] The phase shift mask blank according to [7], further comprising a fourth layer composed of a single layer or a plurality of layers made of a material containing chromium, on the third layer.
[11] The second layer is a processing auxiliary film that functions as a hard mask in forming the pattern of the phase shift film and functions as an etching stopper in forming the pattern of the third layer. Is a light-shielding film, or a combination of a light-shielding film and an anti-reflection film, and the fourth layer is a processing auxiliary film that functions as a hard mask in forming the pattern of the third layer. 10] The phase shift mask blank according to the above.
[12] The phase shift according to any one of [1] to [11], wherein the phase shift film is a film formed by sputtering and then heat-treated at 400 ° C. or more for 5 minutes or more. Mask blanks.
[13] A phase shift mask formed using the phase shift mask blank according to any one of [1] to [12].
[14] A method for manufacturing a phase shift mask blank, comprising a step of forming a phase shift film on a transparent substrate by sputtering,
The step of forming the phase shift film,
(A) On a transparent substrate, an argon gas and a nitrogen gas are introduced into a sputtering chamber by using a sputtering apparatus and at least one silicon target to form a layer composed of a silicon-based material including silicon and nitrogen. Forming step, and (B) sputtering argon gas and at least one gas selected from nitrogen gas, oxygen gas and nitrogen oxide gas on the transparent substrate using at least one silicon target using a sputtering apparatus. Including one or both of steps of forming a layer composed of a silicon-based material composed of silicon, nitrogen and oxygen by introducing into a chamber,
The method for producing a phase shift mask blank, further comprising a step of subjecting the phase shift film formed on the transparent substrate to a heat treatment at 400 ° C. or more for 5 minutes or more.

  ADVANTAGE OF THE INVENTION According to this invention, it is a thinner phase shift film | membrane which is advantageous in the processing of a photomask pattern. Phase shift mask blanks that provide a high-quality phase shift mask blank excellent in dimensional controllability with less decrease in phase shift, and a phase shift mask blank and a phase shifter that include a phase shift film in which a phase difference required as a phase shift film is secured A shift mask can be provided. ADVANTAGE OF THE INVENTION According to the phase shift mask of this invention, the exposure which respond | corresponds to the demand of further refinement | miniaturization of a pattern in photolithography and high precision is possible.

It is sectional drawing which shows an example of the phase shift mask blank of this invention, and a phase shift mask. It is sectional drawing which shows the other example of the phase shift mask blank of this invention.

Hereinafter, the present invention will be described in more detail.
The phase shift mask blank (phase shift type photomask blank) of the present invention has a single layer or a multilayer (that is, two or more layers) phase shift film formed on a transparent substrate such as a quartz substrate. In the present invention, as the transparent substrate, a transparent substrate called a 6025 substrate having a size of 6 inches square and a thickness of 25 mm inches, which is defined in the SEMI standard, is targeted. Expressed as a 6.35 mm transparent substrate. Further, the phase shift mask (phase shift type photomask) of the present invention has a mask pattern (photomask pattern) of the phase shift film. The phase shift film of the present invention includes a halftone phase shift film. Therefore, the phase shift mask blank of the present invention includes a halftone phase shift mask blank, and the phase shift mask of the present invention includes a halftone phase shift mask.

  FIG. 1A is a cross-sectional view illustrating an example of the phase shift mask blank of the present invention. The phase shift mask blank 100 includes a transparent substrate 10 and a phase shift film 1 formed on the transparent substrate 10. Prepare. FIG. 1B is a cross-sectional view illustrating an example of the phase shift mask of the present invention. The phase shift mask 101 includes a transparent substrate 10 and a phase shift film pattern 11 formed on the transparent substrate 10. Is provided.

  The phase shift film may be composed of a single layer so as to satisfy the phase difference and transmittance required as a phase shift film. For example, in order to satisfy a predetermined surface reflectance, an anti-reflection function It is also preferable to include a layer having the following structure, and to constitute a multilayer so as to satisfy the phase difference and the transmittance required as a phase shift film as a whole.

  In either case of a single layer or a multilayer, each layer may be formed such that the composition changes continuously in the thickness direction. In the case where the phase shift film is formed of multiple layers, a combination of two or more layers selected from layers having different constituent elements and layers having the same constituent elements and different composition ratios may be used. If they are not adjacent layers, the same layers can be combined.

  The phase shift film according to the present invention has a predetermined thickness with respect to light having a wavelength of 200 nm or less, particularly, exposure light of ArF excimer laser light (wavelength of 193 nm) used in photolithography using a phase shift mask. This film gives a phase shift amount (phase difference) and a predetermined transmittance.

  The total thickness of the phase shift film of the present invention is preferably 70 nm or less, more preferably 62 nm or less, since the thinner the thinner the finer pattern is, the easier it is to form. On the other hand, the lower limit of the thickness of the phase shift film is set within a range in which necessary optical characteristics can be obtained for light having a wavelength of 200 nm or less, which is an exposure wavelength, and is not particularly limited, but is generally 40 nm or more. .

The phase difference of the phase shift film of the present invention with respect to the exposure light is the phase difference of the exposure light passing therethrough at the boundary between the portion where the phase shift film exists (phase shift portion) and the portion where the phase shift film does not exist. As long as the exposure light interferes to increase the contrast, the phase difference may be 150 to 200 °. In a general phase shift film, the phase difference is set to approximately 180 °, but from the viewpoint of increasing the contrast described above, the phase difference is not limited to approximately 180 °, and the phase difference is set to be smaller or larger than 180 °. Can be. For example, if the phase difference is smaller than 180 °, it is effective for thinning. In addition, from the point that a higher contrast is obtained, it is needless to say that the phase difference is more effective when the phase difference is closer to 180 °, and is preferably 160 to 190 °, particularly 175 to 185 °, and particularly preferably about 180 °. .

  In the phase shift film of the present invention, the amount of change (ΔTIR) of the warp within 142 mm square at the center of the transparent substrate surface is 0.2 μm or less in absolute value between the state where the phase shift film is present on the transparent substrate. It is preferable that Further, the phase shift film of the present invention, between the state where the phase shift film is present on the transparent substrate, and after all of the phase shift film present on the transparent substrate is removed by etching, the transparent substrate surface center portion It is preferable that the amount of change (ΔTIR) of the warp within a 142 mm square is 0.2 μm or less in absolute value. When the phase shift film has such a small amount of change in the warp, a phase shift and a decrease in dimensional accuracy at the time of forming a phase shift mask by forming a pattern of the phase shift film are small. A phase shift mask blank having a shift film and a phase shift mask can be provided.

Here, the 142 mm square in the central part of the transparent substrate surface is set as a range inside 5 mm from the periphery of the surface of the 152 mm square transparent substrate on which the phase shift film is formed. This range is an area in the phase shift mask where a photomask pattern used for exposure using the phase shift mask is formed. The warpage of the transparent substrate and the transparent substrate on which the phase shift film is formed is the flatness specified by TIR (Total Indicator Reading) when the surface shape is measured by a flatness measuring instrument, and the amount of change thereof is as follows. ΔTIR is the height of the center of the substrate at the time of measuring the surface shape of the substrate, which is defined as the origin in the height direction. It is defined as the maximum value or the minimum value of the amount of change in coordinates. The warpage and the amount of change is measured by a commercially available measuring apparatus flatness tester (e.g., such as CORNING made Tropel ^R Ultra Flat ^TM 200Mask), it can be calculated.

  When the phase shift film of the present invention is a halftone phase shift film, its transmittance to exposure light is preferably 3% or more, particularly 5% or more, and 40% or less, particularly 30% or less. Is preferred.

  In particular, when the phase shift film is made of a silicon-based material including silicon and nitrogen, by adjusting the amounts of silicon and nitrogen in the phase shift film, the transmittance is 3% for light having a wavelength of 200 nm or less. A halftone phase shift film of less than 20% can be obtained. When the phase shift film is made of a silicon-based material composed of silicon, nitrogen and oxygen, by adjusting the amounts of silicon, nitrogen and oxygen in the phase shift film, light having a wavelength of 200 nm or less can be transmitted. A halftone phase shift film having a ratio of 20% or more can be obtained.

  In the phase shift film of the present invention, when it is composed of a single layer, it is provided on the entire single layer, and when it is composed of multiple layers, one or more layers constituting the multilayer, particularly a surface oxide layer described later is provided. In this case, except for the surface oxide layer, the refractive index n to the exposure light in the entire multilayer is preferably 2.4 or more, particularly 2.5 or more, especially 2.6 or more. By lowering the oxygen content of the phase shift film, preferably by not including oxygen or by including a transition metal, it is possible to increase the refractive index n of the film at a predetermined transmittance, The thickness of the film can be further reduced while securing the phase difference required for the shift film. The lower the oxygen content, the higher the refractive index n. The higher the refractive index n, the more the required retardation can be obtained with a thin film.

  In the phase shift film of the present invention, when it is composed of a single layer, it is provided on the entire single layer, and when it is composed of multiple layers, one or more layers constituting the multilayer, particularly a surface oxide layer described later is provided. In this case, it is preferable that the extinction coefficient k for exposure light is 0.1 or more, especially 0.2 or more, 0.7 or less, especially 0.65 or less in the whole multilayer except for the surface oxide layer.

  The phase shift film of the present invention includes at least one layer of a silicon-based material composed of silicon and nitrogen or a silicon-based material composed of silicon, nitrogen and oxygen. The silicon-based material contains silicon and nitrogen, and may contain oxygen. The inclusion of elements other than these is permissible as long as the amount is an impurity, but it is particularly preferable that transition metals (eg, molybdenum, zirconium, tungsten, titanium, hafnium, chromium, tantalum, etc.) are not contained. The problem of pattern size fluctuation deterioration in a silicon-based material containing a transition metal can be improved by using such a silicon-based material, and by using such a silicon-based material, resistance to chemical cleaning can be improved. Improves chemical properties.

  When the phase shift film is composed of multiple layers, the thickness of a silicon-based material composed of silicon and nitrogen or a layer composed of a silicon-based material composed of silicon, nitrogen and oxygen (when the number of layers is two or more, the total Is preferably 60% or more, more preferably 80% or more of the thickness of the entire phase shift film. In particular, when a surface oxide layer described later is provided, the entire multilayer except for the surface oxide layer is formed by: It is preferable that the layer is made of a silicon-based material composed of silicon and nitrogen or a silicon-based material composed of silicon, nitrogen and oxygen. Furthermore, when the phase shift film is composed of a multilayer, a silicon-based material composed of silicon and nitrogen or a layer composed of a silicon-based material composed of silicon and nitrogen and oxygen, the transparent substrate side, the side separated from the transparent substrate side, It may be provided at any of the central portions in the thickness direction.

  When the phase shift film of the present invention is composed of a single layer, the silicon-based material of the entire single layer, and when composed of multiple layers, one or more silicon-based materials of the layers constituting the multilayer, in particular, When a surface oxide layer described below is provided, the silicon content of the silicon-based material in the entire multilayer is 30 atomic% or more, particularly 40 atomic% or more, and especially 44 atomic%, excluding this surface oxide layer. As described above, the content is preferably 55 atomic% or less, particularly preferably 50 atomic% or less. In particular, when the phase shift film is a halftone phase shift film having a low transmittance (for example, 3% or more and less than 20%, particularly 3% or more and 12% or less, particularly 3% or more and less than 10%), it is included in the silicon-based material. The content of silicon is preferably at least 40 at%, particularly at least 44 at%, and is at most 55 at%, especially at most 50 at%, and the phase shift film has a high transmittance (for example, 20 to 30 at%). % Or less), the content of silicon contained in the silicon-based material may be 30 atomic% or more, particularly 40 atomic% or more, and 55 atomic% or less, particularly 45 atomic% or less. preferable.

  When the phase shift film of the present invention is composed of a single layer, the silicon-based material of the entire single layer, and when composed of multiple layers, one or more silicon-based materials of the layers constituting the multilayer, in particular, When a surface oxide layer to be described later is provided, the content of nitrogen contained in the silicon material is 10 atomic% or more, particularly 40 atomic% or more, and especially 50 atomic% in the silicon-based material of the entire multilayer except for this surface oxide layer. As described above, the content is preferably at most 60 atomic%, particularly preferably at most 55 atomic%. In particular, when the phase shift film is a halftone phase shift film having a low transmittance (for example, 3% or more and less than 20%, particularly 3% or more and 12% or less, particularly 3% or more and less than 10%), it is included in the silicon-based material. The nitrogen content is preferably at least 44 at% and at most 60 at%, particularly preferably at most 56 at%, and the phase shift film has a high transmittance (for example, 20 to 30%) halftone. In the case of a phase shift film, the content of nitrogen contained in the silicon-based material is preferably at least 10 at%, particularly at least 40 at%, and is at most 60 at%, especially at most 55 at%.

  When the phase shift film of the present invention is composed of a single layer, it is composed of a single-layer silicon-based material. When a surface oxidized layer is provided, the content of oxygen contained in the silicon-based material is 50 atomic% or less, particularly 20 atomic% or less, particularly 6 atomic% or less in the silicon-based material of the entire multilayer except for the surface oxidized layer. It is preferable that In particular, when the halftone phase shift film has a low transmittance (for example, 3% or more and less than 20%, particularly 3% or more and 12% or less, particularly 3% or more and less than 10%), the content of oxygen contained in the silicon-based material is reduced. It is preferably at least 0 atomic% and at most 6 atomic%, particularly preferably at most 3.5%, particularly preferably at most 1%, and the halftone phase shift film has a high transmittance (for example, at least 20% and at most 30%). In the case of), the content of oxygen contained in the silicon-based material is preferably 50 atomic% or less, particularly preferably 20 atomic% or less, and particularly, the oxygen content contained in the silicon-based material is 0 atomic% or more, In particular, it is preferable that one or more layers contain 1 atomic% or more.

  Specific examples of the silicon-based material include a silicon-based material consisting of only silicon and nitrogen (that is, silicon nitride (SiN)) and a silicon-based material consisting of only silicon, nitrogen and oxygen (that is, silicon oxynitride (SiON)). ).

  Furthermore, in order to reduce the thickness of the phase shift film, it is preferable that the oxygen content is low, and it is more preferable that the phase shift film does not contain oxygen. From this viewpoint, it is preferable that the phase shift film include a layer composed of a silicon-based material composed of silicon and nitrogen. For that purpose, it is effective to form the phase shift film with a single layer composed of a silicon-based material composed of silicon and nitrogen, and to form a single layer composed of a silicon-based material composed of silicon and nitrogen. It is also effective to form a multilayer including the above, particularly a multilayer including at least one layer composed of silicon-based material composed of silicon and nitrogen and at least one layer composed of silicon, nitrogen and oxygen.

The phase shift film of the present invention can be formed by applying a known film forming method, but is preferably formed by a sputtering method capable of easily obtaining a film having excellent homogeneity. Any method of sputtering can be used. The target and the sputtering gas are appropriately selected according to the layer configuration and composition. As a target, a silicon target, a silicon nitride target, a target containing both silicon and silicon nitride, or the like may be used. The contents of nitrogen and oxygen are appropriately adjusted by using a sputtering gas, a reactive gas, a gas containing nitrogen, a gas containing oxygen, a gas containing nitrogen and oxygen, and a gas containing carbon as necessary. It can be adjusted by adjusting and performing reactive sputtering. Specifically, a nitrogen gas (N ₂ gas), an oxygen gas (O ₂ gas), a nitrogen oxide gas (N ₂ O gas, NO gas, NO ₂ gas) or the like can be used as the reactive gas. Further, it is advantageous to use a helium gas, a neon gas, an argon gas, or the like as a rare gas as the sputtering gas from the viewpoint of reducing the amount of change in warpage (ΔTIR).

  The phase shift mask blank of the present invention forms a phase shift film on a transparent substrate by sputtering so as to include at least one layer of a silicon-based material composed of silicon and nitrogen or a silicon-based material composed of silicon, nitrogen and oxygen. Then, it is preferable to form the phase shift film by performing a heat treatment at 400 ° C. or more for 5 minutes or more.

  In the step of forming a phase shift film on a transparent substrate by sputtering, (A) an argon gas and a nitrogen gas are introduced into a sputtering chamber on a transparent substrate using at least one silicon target by using a sputtering apparatus. Forming a layer composed of a silicon-based material composed of silicon and nitrogen, and (B) using a sputtering apparatus and at least one silicon target on a transparent substrate, using an argon gas, a nitrogen gas, Including at least one gas selected from an oxygen gas and a nitrogen oxide gas into a sputtering chamber to form one or both of a step of forming a layer composed of a silicon-based material including silicon, nitrogen, and oxygen Is preferred. At the time of sputtering, the amount of sputter gas introduced during the formation of the phase shift film may be adjusted so that the obtained phase shift film has a small amount of change in warpage (ΔTIR) in the phase shift mask blank. preferable.

  In the heat treatment after the formation of the phase shift film, it is preferable to heat at 400 ° C. or more, particularly 450 ° C. or more, for 5 minutes or more, particularly for 30 minutes or more in a state where the phase shift film is formed on the transparent substrate. Conventionally, in a film containing a transition metal used as a phase shift film, when heat treatment is performed at such a high temperature, a precipitate is formed on the surface and becomes a defect. The phase shift film of the present invention comprising at least one layer of a silicon-based material comprising silicon and nitrogen or a silicon-based material comprising silicon, nitrogen and oxygen is a film containing a transition metal even when such a high temperature is applied. Such a problem does not occur. The heat treatment temperature is preferably 900 ° C. or less, particularly 700 ° C. or less, and the heat treatment time is preferably 24 hours or less, particularly preferably 12 hours or less. The heat treatment may be performed in the sputter chamber, or may be performed by transferring to a heat treatment furnace different from the sputter chamber. The atmosphere of the heat treatment may be an inert gas atmosphere such as a helium gas or an argon gas, even under vacuum, or a surface oxide layer described later may be formed on the outermost surface, but may be an oxygen-containing atmosphere such as an oxygen gas atmosphere. Good.

  When the phase shift film has a multilayer structure, a surface oxide layer can be provided as the outermost surface layer on the surface side (the side separated from the transparent substrate) in order to suppress a change in the film quality of the phase shift film. The oxygen content of this surface oxide layer may be 20 atom% or more, and may be 50 atom% or more. As a method of forming a surface oxide layer, specifically, in addition to oxidation by atmospheric oxidation (natural oxidation), as a method of forcibly oxidizing, a method of treating a silicon-based material film with ozone gas or ozone water, And a method of heating to 300 ° C. or more in an oxygen-containing atmosphere such as an oxygen gas atmosphere by oven heating, lamp annealing, laser heating, or the like. The thickness of the surface oxide layer is preferably 10 nm or less, particularly 5 nm or less, and particularly preferably 3 nm or less. Usually, when the thickness is 1 nm or more, the effect of the oxide layer can be obtained. The surface oxide layer can be formed by increasing the amount of oxygen in the sputtering step, but is preferably formed by the above-described atmospheric oxidation or oxidation treatment in order to reduce the number of defects.

  On the phase shift film of the phase shift mask blank of the present invention, a second layer consisting of a single layer or multiple layers can be provided. The second layer is usually provided adjacent to the phase shift film. Specific examples of the second layer include a light-shielding film, a combination of a light-shielding film and an antireflection film, and a processing auxiliary film functioning as a hard mask in forming a pattern of a phase shift film. When a third layer described later is provided, the second layer can be used as a processing auxiliary film (etching stopper film) that functions as an etching stopper in forming a pattern of the third layer. As a material of the second layer, a material containing chromium is preferable.

  FIG. 2A specifically illustrates such a phase shift mask blank. FIG. 2A is a cross-sectional view illustrating an example of the phase shift mask blank of the present invention. The phase shift mask blank 100 includes a transparent substrate 10, a phase shift film 1 formed on the transparent substrate 10, A second layer 2 formed on the phase shift film 1.

  In the phase shift mask blank of the present invention, a light shielding film can be provided as a second layer on the phase shift film. Further, as the second layer, a combination of a light-shielding film and an anti-reflection film can be provided. By providing the second layer including the light-blocking film, a region for completely blocking exposure light can be provided in the phase shift mask. The light-shielding film and the antireflection film can also be used as a processing auxiliary film in etching. There are many reports (for example, Japanese Patent Application Laid-Open No. 2007-33469 (Patent Document 4) and Japanese Patent Application Laid-Open No. 2007-233179 (Patent Document 5)) on the film configuration and material of the light shielding film and the antireflection film. As a preferable film configuration of a combination of a light-shielding film and an anti-reflection film, for example, a light-shielding film of a material containing chromium is provided, and further, an anti-reflection film of a material containing chromium that reduces reflection from the light-shielding film is provided. And the like. Each of the light-shielding film and the antireflection film may be composed of a single layer or a multilayer. Materials containing chromium for the light shielding film and the antireflection film include chromium alone, chromium oxide (CrO), chromium nitride (CrN), chromium carbide (CrC), chromium oxynitride (CrON), and chromium oxycarbide (CrOC). ), Chromium nitrided carbide (CrNC), chromium oxynitride carbide (CrONC) and the like.

  When the second layer is a light-shielding film or a combination of a light-shielding film and an anti-reflection film, the chromium content in the chromium compound of the light-shielding film is at least 40 atomic%, particularly at least 60 atomic% and less than 100 atomic%. It is preferably at most 99 atomic%, particularly preferably at most 90 atomic%. The oxygen content is 0 atomic% or more, preferably 60 atomic% or less, particularly preferably 40 atomic% or less, and when the etching rate needs to be adjusted, it is preferably 1 atomic% or more. The nitrogen content is 0 atomic% or more, preferably 50 atomic% or less, particularly preferably 40 atomic% or less. When it is necessary to adjust the etching rate, it is preferably 1 atomic% or more. The carbon content is 0 atomic% or more, preferably 20 atomic% or less, particularly preferably 10 atomic% or less. When it is necessary to adjust the etching rate, it is preferably 1 atomic% or more. In this case, the total content of chromium, oxygen, nitrogen and carbon is preferably at least 95 atomic%, more preferably at least 99 atomic%, particularly preferably 100 atomic%.

  When the second layer is a combination of a light-shielding film and an anti-reflection film, the anti-reflection film is preferably a chromium compound, and the chromium content in the chromium compound is 30 atomic% or more, particularly 35 atomic%. As described above, the content is preferably 70 atomic% or less, particularly preferably 50 atomic% or less. The oxygen content is preferably at most 60 atomic%, more preferably at least 1 atomic%, particularly preferably at least 20 atomic%. The nitrogen content is preferably at most 50 at%, particularly at most 30 at%, more preferably at least 1 at%, particularly preferably at least 3 at%. The carbon content is 0 atomic% or more, preferably 20 atomic% or less, particularly preferably 5 atomic% or less, and when the etching rate needs to be adjusted, it is preferably 1 atomic% or more. In this case, the total content of chromium, oxygen, nitrogen and carbon is preferably at least 95 atomic%, more preferably at least 99 atomic%, particularly preferably 100 atomic%.

  When the second layer is a light-shielding film or a combination of a light-shielding film and an antireflection film, the thickness of the second layer is usually 20 to 100 nm, preferably 40 to 70 nm. Further, it is preferable that the total optical density of the phase shift film and the second layer with respect to the exposure light having a wavelength of 200 nm or less is 2.0 or more, particularly 2.5 or more, especially 3.0 or more.

  A third layer consisting of a single layer or multiple layers can be provided on the second layer of the phase shift mask blank of the present invention. The third layer is usually provided adjacent to the second layer. Specific examples of the third layer include a processing auxiliary film functioning as a hard mask in forming a pattern of the second layer, a light-shielding film, and a combination of a light-shielding film and an antireflection film. As the material of the third layer, a material containing silicon is preferable, and a material containing no chromium is particularly preferable.

  Specific examples of such a phase shift mask blank include those shown in FIG. FIG. 2B is a cross-sectional view illustrating an example of the phase shift mask blank of the present invention. The phase shift mask blank 100 includes a transparent substrate 10, a phase shift film 1 formed on the transparent substrate 10, The semiconductor device includes a second layer 2 formed on the phase shift film 1 and a third layer 3 formed on the second layer 2.

When the second layer is a light-shielding film or a combination of a light-shielding film and an anti-reflection film, a processing auxiliary film (etching mask film) functioning as a hard mask in forming a pattern of the second layer is used as the third layer. Can be provided. When a fourth layer described later is provided, the third layer can be used as a processing auxiliary film (etching stopper film) that functions as an etching stopper in forming a pattern of the fourth layer. This processing auxiliary film is made of a material having etching characteristics different from those of the second layer, for example, a material having resistance to chlorine-based dry etching applied to etching of a material containing chromium, specifically, SF ₆ or CF ₄ It is preferable to use a silicon-containing material which can be etched with a fluorine-based gas. Specifically as a material containing silicon, silicon alone, a material containing silicon and one or both of nitrogen and oxygen, a material containing silicon and a transition metal, silicon and one or both of nitrogen and oxygen, Silicon compounds such as materials containing metals and the like are mentioned, and transition metals include molybdenum, tantalum, zirconium and the like.

  When the third layer is a processing auxiliary film, the processing auxiliary film is preferably a silicon compound, and the silicon content in the silicon compound is 20 atomic% or more, particularly 33 atomic% or more, and 95 atomic% or less, In particular, it is preferably at most 80 atomic%. The nitrogen content is preferably at least 0 atomic% and at most 50 atomic%, particularly preferably at most 30 atomic%. When it is necessary to adjust the etching rate, it is preferably at least 1 atomic%. The oxygen content is 0 atomic% or more, particularly 20 atomic% or more, preferably 70 atomic% or less, particularly preferably 66 atomic% or less, and when the etching rate needs to be adjusted, it is 1 atomic% or more. Is preferred. The content of the transition metal is 0 atomic% or more, preferably 35 atomic% or less, particularly preferably 20 atomic% or less. When the transition metal is contained, it is preferably 1 atomic% or more. In this case, the total content of silicon, oxygen, nitrogen and transition metal is preferably at least 95 atomic%, more preferably at least 99 atomic%, particularly preferably 100 atomic%.

  When the second layer is a light-shielding film or a combination of a light-shielding film and an antireflection film, and the third layer is a processing auxiliary film, the thickness of the second layer is usually 20 to 100 nm, preferably 40 to 70 nm. The thickness of the third layer is usually 1 to 30 nm, preferably 2 to 15 nm. Further, it is preferable that the total optical density of the phase shift film and the second layer with respect to the exposure light having a wavelength of 200 nm or less is 2.0 or more, particularly 2.5 or more, especially 3.0 or more.

  When the second layer is a processing auxiliary film, a light-shielding film can be provided as the third layer. Further, as the third layer, a combination of a light-shielding film and an anti-reflection film can be provided. In this case, the second layer is a processing auxiliary film (etching mask film) that functions as a hard mask in forming the pattern of the phase shift film, and a processing auxiliary film (etching) that functions as an etching stopper in forming the pattern of the third layer. (Stopper film). As an example of the processing auxiliary film, there is a film made of a material containing chromium as disclosed in Japanese Patent Application Laid-Open No. 2007-241065 (Patent Document 6). The processing auxiliary film may be composed of a single layer or a multilayer. Materials containing chromium for the processing auxiliary film include chromium alone, chromium oxide (CrO), chromium nitride (CrN), chromium carbide (CrC), chromium oxynitride (CrON), chromium oxycarbide (CrOC), chromium Chromium compounds such as nitrided carbide (CrNC) and chromium oxynitride carbide (CrONC).

  When the second layer is a processing auxiliary film, the content of chromium in the second layer is 40 atom% or more, especially 50 atom% or more, 100 atom% or less, particularly 99 atom% or less, especially 90 atom% or less. The following is preferred. The oxygen content is 0 atomic% or more, preferably 60 atomic% or less, particularly preferably 55 atomic% or less, and when the etching rate needs to be adjusted, it is preferably 1 atomic% or more. The nitrogen content is 0 atomic% or more, preferably 50 atomic% or less, particularly preferably 40 atomic% or less. When it is necessary to adjust the etching rate, it is preferably 1 atomic% or more. The carbon content is 0 atomic% or more, preferably 20 atomic% or less, particularly preferably 10 atomic% or less. When it is necessary to adjust the etching rate, it is preferably 1 atomic% or more. In this case, the total content of chromium, oxygen, nitrogen and carbon is preferably at least 95 atomic%, more preferably at least 99 atomic%, particularly preferably 100 atomic%.

On the other hand, the light-shielding film and the antireflection film of the third layer are made of a material having etching characteristics different from those of the second layer, for example, a material having resistance to chlorine-based dry etching applied to etching of a material containing chromium. It is preferable to use a material containing silicon that can be etched with a fluorine-based gas such as SF ₆ or CF ₄ . Specifically as a material containing silicon, silicon alone, a material containing silicon and one or both of nitrogen and oxygen, a material containing silicon and a transition metal, silicon and one or both of nitrogen and oxygen, Silicon compounds such as materials containing metals and the like are mentioned, and transition metals include molybdenum, tantalum, zirconium and the like.

  When the third layer is a light-shielding film or a combination of a light-shielding film and an antireflection film, the light-shielding film and the antireflection film are preferably a silicon compound, and the content of silicon in the silicon compound is 10 atomic% or more. It is preferably at least 30 atomic% and less than 100 atomic%, particularly preferably at most 95 atomic%. The nitrogen content is 0 atomic% or more, 50 atomic% or less, particularly preferably 40 atomic% or less, particularly preferably 20 atomic% or less, and when the etching rate needs to be adjusted, it is 1 atomic% or more. Is preferred. The oxygen content is preferably at least 0 atomic% and at most 60 atomic%, particularly preferably at most 30 atomic%. When it is necessary to adjust the etching rate, it is preferably at least 1 atomic%. The content of the transition metal is 0 atomic% or more, preferably 35 atomic% or less, particularly preferably 20 atomic% or less. When the transition metal is contained, it is preferably 1 atomic% or more. In this case, the total content of silicon, oxygen, nitrogen and transition metal is preferably at least 95 atomic%, more preferably at least 99 atomic%, particularly preferably 100 atomic%.

  When the second layer is a processing auxiliary film and the third layer is a light-shielding film or a combination of a light-shielding film and an antireflection film, the thickness of the second layer is usually 1 to 20 nm, preferably 2 to 10 nm. The thickness of the third layer is usually 20 to 100 nm, preferably 30 to 70 nm. The total optical density of the phase shift film, the second layer, and the third layer with respect to exposure light having a wavelength of 200 nm or less is adjusted to 2.0 or more, particularly 2.5 or more, and particularly 3.0 or more. Is preferred.

  On the third layer of the phase shift mask blank of the present invention, a fourth layer composed of a single layer or multiple layers can be provided. The fourth layer is usually provided adjacent to the third layer. Specific examples of the fourth layer include a processing auxiliary film that functions as a hard mask in forming a pattern of the third layer. As the material of the fourth layer, a material containing chromium is preferable.

  Specific examples of such a phase shift mask blank include those shown in FIG. FIG. 2C is a cross-sectional view illustrating an example of the phase shift mask blank of the present invention. The phase shift mask blank 100 includes a transparent substrate 10, a phase shift film 1 formed on the transparent substrate 10, A second layer 2 formed on the phase shift film 1, a third layer 3 formed on the second layer 2, and a fourth layer 4 formed on the third layer 3 Prepare.

  When the third layer is a light-shielding film or a combination of a light-shielding film and an anti-reflection film, a processing auxiliary film (etching mask film) functioning as a hard mask in forming a pattern of the third layer is used as the fourth layer. Can be provided. This processing auxiliary film is made of a material having etching characteristics different from that of the third layer, for example, a material having resistance to fluorine-based dry etching applied to etching of a material containing silicon, specifically, a chlorine-based material containing oxygen. It is preferable to use a material containing chromium that can be etched by gas. Specific examples of the material containing chromium include chromium alone, chromium oxide (CrO), chromium nitride (CrN), chromium carbide (CrC), chromium oxynitride (CrON), chromium oxycarbide (CrOC), and chromium nitride. Chromium compounds such as carbide (CrNC) and chromium oxynitride carbide (CrONC) are exemplified.

  When the fourth layer is a processing auxiliary film, the chromium content in the fourth layer is at least 40 atomic%, particularly at least 50 atomic%, and at most 100 atomic%, particularly at most 99 atomic%, especially at least 90 atomic%. The following is preferred. The oxygen content is 0 atomic% or more, preferably 60 atomic% or less, particularly preferably 40 atomic% or less, and when the etching rate needs to be adjusted, it is preferably 1 atomic% or more. The nitrogen content is 0 atomic% or more, preferably 50 atomic% or less, particularly preferably 40 atomic% or less. When it is necessary to adjust the etching rate, it is preferably 1 atomic% or more. The carbon content is 0 atomic% or more, preferably 20 atomic% or less, particularly preferably 10 atomic% or less. When it is necessary to adjust the etching rate, it is preferably 1 atomic% or more. In this case, the total content of chromium, oxygen, nitrogen and carbon is preferably at least 95 atomic%, more preferably at least 99 atomic%, particularly preferably 100 atomic%.

  When the second layer is a processing auxiliary film, the third layer is a light shielding film, or a combination of a light shielding film and an antireflection film, and the fourth layer is a processing auxiliary film, the thickness of the second layer is usually 1 to 20 nm, preferably 2 to 10 nm, the thickness of the third layer is usually 20 to 100 nm, preferably 30 to 70 nm, and the thickness of the fourth layer is usually 1 to 30 nm, preferably 2 to 20 nm. The total optical density of the phase shift film, the second layer, and the third layer with respect to exposure light having a wavelength of 200 nm or less is adjusted to 2.0 or more, particularly 2.5 or more, and particularly 3.0 or more. Is preferred.

  The second layer and the fourth layer made of a chromium-containing material are formed using a chromium target, a target in which chromium is added with one or more selected from oxygen, nitrogen, and carbon, and the like. Reactivity using a sputtering gas in which a reactive gas selected from an oxygen-containing gas, a nitrogen-containing gas, a carbon-containing gas, or the like is appropriately added to a rare gas such as Ar, He, or Ne according to the composition of a film to be formed. It can be formed by sputtering.

  On the other hand, the third layer made of a material containing silicon is formed using a silicon target, a silicon nitride target, a target containing both silicon and silicon nitride, a transition metal target, a composite target of silicon and a transition metal, or the like. A reaction using a sputtering gas in which a reactive gas selected from an oxygen-containing gas, a nitrogen-containing gas, a carbon-containing gas, or the like is appropriately added to a rare gas such as Ar, He, Ne, or the like according to the composition of a film to be formed. Can be formed by reactive sputtering.

  The phase shift mask of the present invention can be manufactured from a phase shift mask blank by an ordinary method. For example, in a phase shift mask blank in which a film of a material containing chromium is formed as a second layer on the phase shift film, the phase shift mask can be manufactured by, for example, the following steps.

  First, an electron beam resist film is formed on the second layer of the phase shift mask blank, a pattern is drawn by an electron beam, and a resist pattern is obtained by a predetermined developing operation. Next, using the obtained resist pattern as an etching mask, the resist pattern is transferred to the second layer by chlorine-based dry etching containing oxygen to obtain a pattern of the second layer. Next, using the obtained second layer pattern as an etching mask, the pattern of the second layer is transferred to the phase shift film by fluorine-based dry etching to obtain a phase shift film pattern. Here, if it is necessary to leave a part of the second layer, a resist pattern for protecting the part is formed on the second layer, and then the resist pattern is formed by chlorine-containing dry etching containing oxygen. Remove the portion of the second layer not protected. Then, the resist pattern is removed by an ordinary method to obtain a phase shift mask.

  A light-shielding film of a material containing chromium or a combination of a light-shielding film and an anti-reflection film is formed as a second layer on the phase shift film, and a third layer is formed on the second layer as a third layer. In a phase shift mask blank in which a processing auxiliary film of a material containing silicon is formed, for example, a phase shift mask can be manufactured by the following steps.

  First, an electron beam resist film is formed on the third layer of the phase shift mask blank, a pattern is drawn by an electron beam, and a resist pattern is obtained by a predetermined developing operation. Next, using the obtained resist pattern as an etching mask, the resist pattern is transferred to the third layer by fluorine-based dry etching to obtain a pattern of the third layer. Next, using the obtained pattern of the third layer as an etching mask, the pattern of the third layer is transferred to the second layer by chlorine-containing dry etching containing oxygen, and the pattern of the second layer is formed. obtain. Next, after removing the resist pattern, the pattern of the second layer is transferred to the phase shift film by fluorine-based dry etching using the obtained pattern of the second layer as an etching mask to form a phase shift film pattern. At the same time, the pattern of the third layer is removed. Next, after forming a resist pattern for protecting the portion where the second layer is to be left on the second layer, the second portion of the portion not protected by the resist pattern is subjected to chlorine-containing dry etching containing oxygen. Remove the layer. Then, the resist pattern is removed by an ordinary method to obtain a phase shift mask.

  On the other hand, a processing aid film of a material containing chromium is formed as a second layer on the phase shift film, and a light-shielding film of a material containing silicon as a third layer on the second layer, or In a phase shift mask blank in which a combination of a light shielding film and an antireflection film is formed, for example, a phase shift mask can be manufactured by the following steps.

  First, an electron beam resist film is formed on the third layer of the phase shift mask blank, a pattern is drawn by an electron beam, and a resist pattern is obtained by a predetermined developing operation. Next, using the obtained resist pattern as an etching mask, the resist pattern is transferred to the third layer by fluorine-based dry etching to obtain a pattern of the third layer. Next, by using the obtained third layer pattern as an etching mask, the third layer pattern is transferred to the second layer by oxygen-containing chlorine-based dry etching to remove the phase shift film. To obtain a second layer pattern from which the second layer is removed. Next, a resist pattern for removing the resist pattern and protecting a portion where the third layer is left is formed on the third layer, and then using the obtained second layer pattern as an etching mask, a fluorine-based resist pattern is formed. The pattern of the second layer is transferred to the phase shift film by dry etching to obtain a phase shift film pattern, and at the same time, the portion of the third layer not protected by the resist pattern is removed. Next, the resist pattern is removed by a conventional method. Then, the portion of the second layer from which the third layer has been removed is removed by chlorine-containing dry etching containing oxygen, so that a phase shift mask can be obtained.

  Furthermore, a processing auxiliary film of a material containing chromium is formed as a second layer on the phase shift film, and a light-shielding film of a material containing silicon as a third layer on the second layer, or In a phase shift mask blank in which a combination of a light-shielding film and an anti-reflection film is formed, and a processing assistance film of a material containing chromium is formed as a fourth layer on the third layer, for example, A phase shift mask can be manufactured by the following steps.

  First, an electron beam resist film is formed on the fourth layer of the phase shift mask blank, and a pattern is drawn by an electron beam, and then a resist pattern is obtained by a predetermined developing operation. Next, by using the obtained resist pattern as an etching mask, the resist pattern is transferred to the fourth layer by chlorine-containing dry etching containing oxygen to obtain a pattern of the fourth layer. Next, the pattern of the fourth layer is transferred to the third layer by fluorine-based dry etching using the obtained pattern of the fourth layer as an etching mask to obtain a pattern of the third layer. Next, after removing the resist pattern and forming a resist pattern for protecting a portion where the third layer is left on the fourth layer, oxygen is added using the obtained third layer pattern as an etching mask. The pattern of the third layer is transferred to the second layer by chlorine-containing dry etching to obtain the pattern of the second layer, and at the same time, the portion of the fourth layer that is not protected by the resist pattern is removed. . Next, using the pattern of the second layer as an etching mask, the pattern of the second layer is transferred to the phase shift film by fluorine-based dry etching to obtain a phase shift film pattern, and at the same time, protected by a resist pattern. The portion of the third layer that is not present is removed. Next, the resist pattern is removed by a conventional method. Then, the phase shift mask is obtained by removing the second layer in the portion where the third layer has been removed and the fourth layer in the portion where the resist pattern has been removed by chlorine-containing dry etching containing oxygen. be able to.

The phase mask of the present invention is used for photolithography for forming a pattern having a half pitch of 50 nm or less, particularly 30 nm or less, especially 20 nm or less on a substrate to be processed, by applying an ArF excimer laser beam to a photoresist film formed on the substrate to be processed. (wavelength 193 nm), F ₂ laser beam (wavelength 157 nm) is particularly effective in the exposure of transferring the following pattern with the exposure light wavelength 200nm, such as.

  In the pattern exposure method of the present invention, using a phase shift mask manufactured from a phase shift mask blank, a photomask formed on a substrate to be processed by irradiating a photomask pattern including a pattern of a phase shift film with exposure light. A photomask pattern is transferred to a photoresist film to be exposed to the pattern. Irradiation of exposure light may be exposure under dry conditions, or immersion exposure, but the pattern exposure method of the present invention, in which the amount of cumulative irradiation energy increases in a relatively short time in actual production, particularly by immersion exposure, It is particularly effective when exposing a photomask pattern by immersion exposure using a wafer having a size of 300 mm or more as a substrate to be processed.

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

[Example 1]
In a chamber of the sputtering apparatus, a 152 mm square, 6.35 mm thick 6025 quartz substrate was installed, a silicon target was used as a sputter target, argon gas and nitrogen gas were used as a sputter gas, and power applied to the target was 1,900 W. At a flow rate of argon gas of 17 sccm and a flow rate of nitrogen gas of 40 sccm, a halftone phase shift film made of SiN was formed. The halftone phase shift film after film formation and before forming the amount of change warping of the substrate surface central portion 142mm inside angle (? TIR), measured by CORNING made flatness tester Tropel ^R Ultra Flat ^TM 200Mask (hereinafter (The same applies to the measurement of the amount of change in warp), and the absolute value was 0.22 μm. Thereafter, in a heat treatment furnace, heat treatment was performed at 500 ° C. for 6 hours in an atmosphere in which nitrogen gas and oxygen gas were at about the same as atmospheric partial pressure, to obtain a halftone phase shift mask blank. The absolute value of the amount of change (ΔTIR) of the warpage within the 142 mm square at the center of the substrate surface before forming the halftone phase shift film and after heat treatment was 0.10 μm. After the heat treatment, the halftone phase shift film had a phase difference of 177 °, a transmittance of 19%, and a thickness of 60 nm. When the composition of this film was measured by XPS (X-ray photoelectron spectroscopy, the same applies hereinafter), the atomic ratio was Si: N = 46: 53.

  Next, the entire halftone phase shift film on the quartz substrate of the obtained halftone phase shift mask blank was peeled off by fluorine-based dry etching. The absolute value of the amount of change in warpage (ΔTIR) within a 142 mm square of the central part of the substrate surface before and after the halftone phase shift film was peeled was 0.07 μm.

  An electron beam resist film is formed on a second layer of a phase shift mask blank in which a second layer containing Cr is formed on a halftone phase shift film made of SiN formed under the same conditions, After performing a pattern drawing by an electron beam, a resist pattern is obtained by a predetermined developing operation, and the obtained resist pattern is used as an etching mask to dry-etch the resist pattern on the second layer by chlorine-containing dry etching containing oxygen. The pattern of the second layer is transferred to form a pattern of the second layer. The pattern of the second layer is transferred to the phase shift film by fluorine-based dry etching using the obtained pattern of the second layer as an etching mask. A shift film pattern was obtained, and the resist pattern and the second layer were removed by a conventional method, thereby obtaining a phase shift mask. Further, the obtained phase shift mask could be corrected by a correction device using an electron beam.

[Example 2]
A 152 mm square, 6.35 mm thick 6025 quartz substrate was placed in a chamber of a sputtering apparatus, a silicon target was used as a sputtering target, argon gas, nitrogen gas, and oxygen gas were used as sputtering gases, and power applied to the target was 1 unit. , 900 W, an argon gas flow rate of 15 sccm, a nitrogen gas flow rate of 40 sccm, and an oxygen gas flow rate of 2 sccm, to form a halftone phase shift film made of SiON. Thereafter, in a heat treatment furnace, heat treatment was performed at 500 ° C. for 6 hours in an atmosphere in which nitrogen gas and oxygen gas were at about the same as atmospheric partial pressure, to obtain a halftone phase shift mask blank. The absolute value of the amount of change in warpage (ΔTIR) in the central 142 mm square of the substrate surface before the formation of the halftone phase shift film and after the heat treatment was 0.15 μm. After the heat treatment, the halftone phase shift film had a phase difference of 175 °, a transmittance of 24%, and a thickness of 63 nm. When the composition of this film was measured by XPS, the atomic ratio was Si: N: O = 43: 48: 8.

  Next, the entire halftone phase shift film on the quartz substrate of the obtained halftone phase shift mask blank was peeled off by fluorine-based dry etching. The absolute value of the amount of change (ΔTIR) of the warpage within the 142 mm square at the center of the substrate surface before and after the halftone phase shift film was peeled was 0.18 μm.

[Example 3]
A 152 mm square, 6.35 mm thick 6025 quartz substrate was placed in a chamber of a sputtering apparatus, a silicon target was used as a sputtering target, argon gas, nitrogen gas, and oxygen gas were used as sputtering gases, and power applied to the target was 1 unit. , 900 W, a flow rate of argon gas of 15 sccm and a flow rate of nitrogen gas of 40 sccm, after forming a layer made of SiN, subsequently applying power to the target at 1,900 W, a flow rate of argon gas of 10 sccm, and a flow rate of nitrogen gas. At a flow rate of 40 sccm and an oxygen gas flow rate of 10 sccm, a layer made of SiON was formed, and a halftone phase shift film in which a layer made of SiN and a layer made of SiON were stacked was formed. Thereafter, in a heat treatment furnace, heat treatment was performed at 500 ° C. for 6 hours in an atmosphere in which nitrogen gas and oxygen gas were at about the same as atmospheric partial pressure, to obtain a halftone phase shift mask blank. The absolute value of the amount of change in warpage (ΔTIR) within a 142 mm square center portion of the substrate surface before forming the halftone phase shift film and after heat treatment was 0.17 μm. After the heat treatment, the halftone phase shift film had a phase difference of 177 °, a transmittance of 29%, and a thickness of 66 nm. When the composition of this film was measured by XPS, the layer of SiN was Si: N = 45: 54 in atomic ratio, and the layer of SiON was Si: N: O = 38: 20: 41 in atomic ratio. Met.

  Next, the entire halftone phase shift film on the quartz substrate of the obtained halftone phase shift mask blank was peeled off by fluorine-based dry etching. The absolute value of the amount of change in warpage (ΔTIR) within the 142 mm square of the central part of the substrate surface before and after peeling the halftone phase shift film was 0.19 μm.

[Example 4]
In a chamber of the sputtering apparatus, a 152 mm square, 6.35 mm thick 6025 quartz substrate was installed, a silicon target was used as a sputter target, argon gas and nitrogen gas were used as a sputter gas, and power applied to the target was 1,900 W. With a flow rate of argon gas of 17 sccm and a flow rate of nitrogen gas of 30 sccm, a halftone phase shift film made of SiN was formed. The absolute value of the amount of change in warpage (ΔTIR) within a 142 mm square at the center of the substrate surface before and after forming the halftone phase shift film was 0.41 μm. Thereafter, in a heat treatment furnace, heat treatment was performed at 500 ° C. for 6 hours in an atmosphere in which nitrogen gas and oxygen gas were at about the same as atmospheric partial pressure, to obtain a halftone phase shift mask blank. The absolute value of the amount of change in warpage (ΔTIR) within the 142 mm square at the center of the substrate surface before forming the halftone phase shift film and after heat treatment was 0.06 μm. After the heat treatment, the halftone phase shift film had a phase difference of 179 °, a transmittance of 7%, and a thickness of 61 nm. When the composition of this film was measured by XPS, the atomic ratio was Si: N = 47: 52.

  Next, the entire halftone phase shift film on the quartz substrate of the obtained halftone phase shift mask blank was peeled off by fluorine-based dry etching. The absolute value of the amount of change (ΔTIR) of the warpage in the 142 mm square at the center of the substrate surface before and after the halftone phase shift film was peeled was 0.08 μm.

[Comparative Example 1]
A 152 mm square, 6.35 mm thick 6025 quartz substrate was placed in a chamber of a sputtering apparatus, a silicon target was used as a sputtering target, a nitrogen gas was used as a sputtering gas, and power applied to the target was 1,900 W. At a flow rate of 50 sccm, a halftone phase shift film made of SiN was formed. Thereafter, in a heat treatment furnace, heat treatment was performed at 500 ° C. for 6 hours in an atmosphere in which nitrogen gas and oxygen gas were at about the same as atmospheric partial pressure, to obtain a halftone phase shift mask blank. The absolute value of the amount of change in warpage (ΔTIR) within a 142 mm square at the center of the substrate surface before forming the halftone phase shift film and after heat treatment was 0.44 μm. After the heat treatment, the halftone phase shift film had a phase difference of 175 °, a transmittance of 18%, and a thickness of 60 nm. When the composition of this film was measured by XPS, the atomic ratio was Si: N = 45: 54.

  Next, the entire halftone phase shift film on the quartz substrate of the obtained halftone phase shift mask blank was peeled off by fluorine-based dry etching. The absolute value of the amount of change in warpage (ΔTIR) within the 142 mm square at the center of the substrate surface before and after peeling the halftone phase shift film was 0.45 μm.

[Comparative Example 2]
In a chamber of the sputtering apparatus, a 152 mm square, 6.35 mm thick 6025 quartz substrate was installed, a silicon target was used as a sputter target, argon gas and nitrogen gas were used as a sputter gas, and power applied to the target was 1,900 W. With a flow rate of argon gas of 17 sccm and a flow rate of nitrogen gas of 30 sccm, a halftone phase shift film made of SiN was formed. The absolute value of the amount of change in warpage (ΔTIR) within a 142 mm square at the center of the substrate surface before and after forming the halftone phase shift film was 0.41 μm. Thereafter, in a heat treatment furnace, a heat treatment was performed at 300 ° C. for 6 hours in an atmosphere in which nitrogen gas and oxygen gas were substantially equal to the atmospheric partial pressure, to obtain a halftone phase shift mask blank. The absolute value of the amount of change in warpage (ΔTIR) within a 142 mm square at the center of the substrate surface before forming the halftone phase shift film and after heat treatment was 0.24 μm. After the heat treatment, the halftone phase shift film had a phase difference of 179 °, a transmittance of 7%, and a thickness of 61 nm. When the composition of this film was measured by XPS, the atomic ratio was Si: N = 47: 52.

  Next, the entire halftone phase shift film on the quartz substrate of the obtained halftone phase shift mask blank was peeled off by fluorine-based dry etching. The absolute value of the amount of change in warpage (ΔTIR) within a 142 mm square central portion of the substrate surface before and after peeling the halftone phase shift film was 0.27 μm.

REFERENCE SIGNS LIST 1 phase shift film 2 second layer 3 third layer 4 fourth layer 10 transparent substrate 11 phase shift film pattern 100 phase shift mask blanks 101 phase shift mask

Claims (5)

On a 152 mm square, 6.35 mm thick transparent substrate, a light having a wavelength of 200 nm or less and a phase shift film having a phase shift amount of 150 to 200 ° are provided.
The phase shift film includes at least one layer of a silicon-based material including silicon and nitrogen or a silicon-based material including silicon, nitrogen, and oxygen, has a transmittance of 3% or more and 12% or less, and has a film thickness of 70 nm or less. A method for manufacturing a phase shift mask blanks,
(1) a step of forming the phase shift film on the transparent substrate by sputtering;
(2) heat-treating the phase shift film formed on the transparent substrate at 500 ° C. to 900 ° C. for 6 hours to 24 hours ,
Step (1) of forming the phase shift film includes:
(A) On a transparent substrate, an argon gas and a nitrogen gas are introduced into a sputtering chamber by using at least one silicon target by using a sputtering apparatus to form a layer of the silicon-based material including silicon and nitrogen. And (B) using a sputtering apparatus and at least one silicon target on a transparent substrate, using an argon gas and at least one gas selected from a nitrogen gas, an oxygen gas, and a nitrogen oxide gas in a sputtering chamber. Introduced into the above, silicon, by a method comprising one or both steps of forming a layer of a silicon-based material consisting of nitrogen and oxygen,
As the above-mentioned phase shift film, the amount of change in the warp within a 142 mm square at the center of the transparent substrate surface (between before the phase shift film is formed on the transparent substrate and when the phase shift film is present on the transparent substrate) ΔTIR) is a halftone phase shift film having an absolute value of not more than 0.2 μm.   2. The method according to claim 1, wherein the light having a wavelength of 200 nm or less is ArF excimer laser light. 3. The method according to claim 1, wherein in the step (2) of heat-treating the phase shift film, a heat treatment temperature is 700 ° C. or less. The method according to any one of claims 1 to 3, wherein in the step (2) of heat-treating the phase shift film, the heat treatment time is 12 hours or less.   The method according to any one of claims 1 to 4, wherein in the step (2) of heat-treating the phase shift film, a heat treatment atmosphere is an inert gas atmosphere or a vacuum.

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